JP2011173981A - Curable resin composition for optical recording medium, cured product and optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an curable resin composition for optical recording media capable of giving a cured product which sufficiently exhibits various properties such as transparency and film thickness-stability, stably inhibits warpage and permanent deformation over a long period, and furthermore has excellent surface smoothness, and enables achieving recoding/reproduction with higher reliability, and a cured product thereof, and an optical recording medium having a layer obtained by curing this resin composition. <P>SOLUTION: The curable resin composition for optical recording media is a curable resin composition to be used in optical media for performing recording and/or reproduction with blue laser beams and includes an alkylene oxide and/or ε-caprolactone-modified tri- or higher functional (meth)acrylate compound, an alkylene oxide and/or ε-caprolactone-modified bifunctional (meth)acrylate compound, a specific (meth)acrylate compound having two or more radically polymerizable unsaturated groups in the molecule, and a photopolymerization initiator. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a curable resin composition for optical recording media, a cured product, and an optical recording medium. More specifically, the present invention relates to a curable resin composition used for an optical recording medium that performs recording and reproduction with blue laser light, a cured product thereof, and an optical recording medium.

In recent years, with the development of information technology, a high-density and large-capacity optical recording medium (optical disk) for storing a large amount of digital information such as music, images and videos for a long period of time has been demanded. For example, the launch of digital high-definition broadcasting has led to the spread of large-screen LCDs and plasma televisions that are compatible with full high-definition, but DVD (digital versatile disc), which is a conventional optical recording medium, has a small recording capacity, High-quality moving images could not be recorded for a long time. Therefore, as a new standard for high-density and large-capacity optical recording media, a Blu-ray Disc (BD) that records and reproduces information with blue laser light has been developed and sold. In this new standard, a blue laser beam with a short wavelength (about 405 nm) and a high numerical aperture (NA) are adopted to increase the capacity, and the capacity is increased to about 5 times or more that of a DVD. Such an optical recording medium usually has a configuration in which a recording layer, a reflective layer, and a light transmission layer are laminated on a substrate. During recording and reproduction, laser light is irradiated to the recording layer through the light transmission layer to perform recording and reproduction. It is a mechanism to be performed.

With respect to the light transmission layer of such an optical recording medium, Patent Document 1 describes that a very high uniformity is required because the uniformity of the thickness greatly affects the recording and reproduction of information. Japanese Patent Application Laid-Open No. H10-228561 describes the necessity for the thickness unevenness from the disk surface to the recording layer to clear a tolerance of ± 2 μm. Patent Document 3 describes that the occurrence of warpage is suppressed by making the product of the film thickness and the elastic modulus of the light transmission layer equal to or less than a certain value, and Patent Document 4 describes that the protective layer is protected. When a laminated sheet is used, it is described that the spot position of the laser beam fluctuates due to scratches such as compression marks and dents that occur when the laminated sheet is wound, and an error in writing or reading data occurs. Yes.

Further, Patent Document 5 discloses a form having a specific elastic modulus and glass transition temperature as a light transmission layer of an optical recording medium capable of achieving both a reduction in warpage of the disk and a reduction in creep of the light transmission layer. . Specifically, as a material for the light transmission layer, a urethane (meth) acrylate oligomer or an epoxy (meth) acrylate oligomer having a glass transition temperature of a single cured product of −50 to 15 ° C., and a glass transition temperature of the single cured product. A bifunctional or higher-functional (meth) acrylate monomer having an aliphatic residue, alicyclic residue or aromatic residue in the main chain or side chain structure at -40 to 90 ° C, and a photopolymerization initiator component. A resin composition is disclosed.

Further, Patent Document 6 discloses a form having a predetermined elastic modulus as a cover layer of an optical recording medium that is considered to have good reliability. Specifically, as a cover layer material having characteristics relating to storage elastic modulus in an environmental test that is allowed to stand at 80 ° C./80% RH for 100 hours, UV comprising a flexible urethane acrylate, a monofunctional acrylate, and a photoinitiator. A curable resin 1 and a UV curable resin 2 composed of urethane acrylate, monofunctional acrylate, polyfunctional acrylate and photoinitiator are disclosed.

JP 2006-351102 A (page 3) JP 2007-115356 A (pages 2 to 3) JP 2007-102980 A (2nd, 5th, 8th, 11th to 14th pages) JP 2008-126518 A (pages 1 and 2) JP 2009-271970 A (2nd, 4th, 9th to 16th pages) JP 2009-026379 A (second, pages 16-18)

As described above, various techniques relating to optical recording media for recording / reproducing information with blue laser light have been studied.
Here, since unevenness in the thickness of the light transmission layer constituting such an optical recording medium affects information recording / reproduction, the thickness of the light transmission layer is required to be uniform. Although it is necessary to control within 100 μm ± 2 to 3 μm, from the viewpoint of stable information recording / reproduction for a long period of time, even when the optical recording medium is stored, the change in the thickness of the light transmission layer is small and high transparency (low Colorability) is also required. Also, if there are scratches (permanent deformation) such as compression marks or dents on the light transmission layer, the laser spot position will fluctuate, and this may also affect the recording / reproduction of information. It is desirable to sufficiently prevent such deformation. Further, the surface smoothness of the light transmission layer is not sufficient. For example, when the surface has irregularities, the recording / reproducing function may be affected. Therefore, the light transmission layer may have surface smoothness. Desired.

In addition, as a method for forming the light transmission layer, mainly a sheet bonding method in which a polycarbonate sheet is bonded with an ultraviolet curable adhesive, and an ultraviolet curable resin is applied by spin coating, and the resin is irradiated with ultraviolet rays. There are two methods, ie, a spin coating method for curing the material, but the spin coating method has become mainstream at present due to cost. Usually, when forming a light transmission layer using an ultraviolet curable resin, film thickness stability is required from the viewpoint of film thickness uniformity and productivity, but the optical recording medium is caused by curing shrinkage of the ultraviolet curable resin. There are many cases where warping occurs. Also, in an optical recording medium that records and reproduces information with blue laser light, the light transmission layer exists only on one side of the substrate (the side on which the laser light is incident), so that the structure is asymmetric in the thickness direction of the optical recording medium. It becomes. Therefore, it has a property that it is easily warped structurally as compared with a DVD or the like having a symmetrical structure in which two substrates are bonded together by an adhesive layer. For this reason, the substrate is warped in advance opposite to the coated surface, or correction or the like is performed with a reproducing / recording device, but if warpage exceeding the allowable range (correctable range) occurs. There are cases where accurate data recording and reproduction on the optical recording medium cannot be performed, and that data cannot be taken in and out of the reproduction / recording apparatus.

Therefore, the resin composition that forms a light transmission layer of an optical recording medium that records and reproduces information with blue laser light has a cured product that has a uniform film thickness, stability, transparency (low coloration) over a long period of time. ) And the like can be sufficiently exhibited, and it is desired that the permanent deformation is sufficiently suppressed and the characteristic that the warpage is remarkably small is sufficiently exhibited. However, none of conventional resin compositions can sufficiently satisfy all of these characteristics. For example, the resin composition described in Patent Document 5 has problems in terms of surface smoothness, permanent deformation, warpage, and the like of a cured film, and cracks may occur when a hard coat layer is further laminated. Therefore, there has been room for improvement in order to obtain a more reliable optical recording medium that can exhibit various characteristics in a balanced manner.

By the way, when a light transmission layer or the like is formed (film formation) by spin coating, irregularities may occur on the surface of the cured film due to the flow trace of the coating agent (ultraviolet curable resin, etc.). May affect recording and playback. As a film forming means, it is best to use a spin coating method in consideration of productivity and efficiency. However, when a light transmission layer or the like is formed by spin coating a resin composition in this way, flowability is improved. There was room for improvement in order to obtain an optical recording medium having a light-transmitting layer having excellent surface smoothness by making (liquid flow property) good.

The present invention has been made in view of the above-mentioned present situation, and can sufficiently exhibit various physical properties such as transparency and film thickness stability, and can stably suppress warping and permanent deformation for a long period of time, and can also provide a smooth surface. Curable resin composition for optical recording media capable of providing a cured product having excellent properties and capable of realizing more reliable recording and reproduction, and the cured product, and such a resin composition is cured. An object of the present invention is to provide an optical recording medium having a layer.

The inventors of the present invention have made various studies on a curable resin composition used for an optical recording medium that performs recording and reproduction using blue laser light. As a result, (a) trifunctional or higher functional group modified with alkylene oxide and / or ε-caprolactone is used. (B) a bifunctional (meth) acrylate compound modified with alkylene oxide and / or ε-caprolactone, and (c) 2 radically polymerizable unsaturated groups in the other molecules. A resin composition containing a specific (meth) acrylate compound having the above, (d) another (meth) acrylate compound as necessary, in a specific content ratio, and further containing (e) a photopolymerization initiator; Then, the cured product can sufficiently exhibit various physical properties such as transparency, film thickness stability and residual film property, and not only the initial warpage is small, but also the warpage at low temperatures. It has been found that it does not increase, and it has remarkably excellent three warping properties (warping resistance) such that the amount of warpage increase during the heating acceleration test is small, and also has high pressure resistance and light resistance. Further, the cured product of such a curable resin composition is particularly suitable for film formation by a spin coating method, and has also been found to have a high level of surface smoothness. It has also been found to be useful for recordable optical recording media. And by using such a curable resin composition, it has been found that an optical recording medium capable of exhibiting recording / reproducing characteristics stably for a long period of time can be obtained with high efficiency and high productivity, and the above-mentioned problems can be solved brilliantly. Thus, the present invention has been achieved.

Here, in this specification, “warping is small” as an effect of the present invention means that not only warpage at the time of curing (initial) is small, but also warpage does not increase even at a low temperature (5 ° C.) and heating is performed. It means that the amount of warpage increase at the time of the acceleration test (70 ° C., 100 hours) is small, and the three warpage properties (warpage resistance) are excellent. Small initial warpage improves the productivity of optical recording media, low warpage at low temperatures provides stable recording / reproduction characteristics, and low warpage during the heating acceleration test provides excellent durability. Therefore, the optical recording medium using the curable resin composition for an optical recording medium of the present invention has stable recording / reproduction characteristics for a long period of time even in a place where it is easily exposed to high temperatures such as in a cold district or in a car. It can be demonstrated.
In addition, as an effect exhibited by the present invention, “excellent in long-term storage stability” means excellent in the above three warping characteristics and residual film properties, and further has a small amount of permanent deformation due to pressure marks, dents, etc. ) Means.

That is, the present invention relates to a curable resin composition used for an optical recording medium for recording and / or reproducing with blue laser light, the curable resin composition comprising (a) alkylene oxide and / or ε-caprolactone. 20 to 75% by mass of a tri- or higher-functional (meth) acrylate compound modified with 1 to 55% by mass, and (b) 1 to 55% by mass of a bifunctional (meth) acrylate compound modified with alkylene oxide and / or ε-caprolactone, (C) Urethane (meth) acrylate compound, polyester (meth) acrylate compound, epoxy (meth) acrylate compound having 2 or more radically polymerizable unsaturated groups in the molecule, and (meth) acryloyl group in the side chain 20 to 60% by weight of at least one compound selected from the group consisting of oligomers or polymers, and (d ) (0) to 20% by mass of the (meth) acrylate compound other than the components (a), (b) and (c) (however, each numerical range includes (a), (b), (c) and ( The content ratio (% by mass) of each component when the total amount of d) is 100% by mass)), and (e) a curable resin composition for optical recording media containing a photopolymerization initiator.
The present invention is also a cured product obtained by curing the curable resin composition for optical recording media.
The present invention is also an optical recording medium having a layer formed by curing the curable resin composition for an optical recording medium.
The present invention is described in detail below.

<Curable resin composition for optical recording medium>
The curable resin composition for optical recording media of the present invention (hereinafter also referred to as “curable resin composition” or “resin composition”) is used for an optical recording medium for recording and / or reproducing with blue laser light. Is. The blue laser beam is preferably a laser beam having a wavelength of about 405 nm. However, when used for an optical recording medium for recording with such a laser beam, that is, a so-called Blu-ray disc, several decades have passed. The advantage that recording and reproduction can be performed stably over a long period of time is remarkably exhibited. Such a curable resin composition can be preferably used for any optical recording medium such as a read-only type (BD-ROM), a write-once type (BD-R), and a rewritable type (BD-RE). From the viewpoint of realizing a highly reliable optical recording medium, it can be suitably applied to a recordable optical recording medium (write-once type, rewritable type, etc.).

The curable resin composition comprises (a) a tri- or higher functional (meth) acrylate compound modified with alkylene oxide and / or ε-caprolactone, and (b) 2 modified with alkylene oxide and / or ε-caprolactone. A functional (meth) acrylate compound, and (c) a urethane (meth) acrylate compound, a polyester (meth) acrylate compound, an epoxy (meth) acrylate compound, and a side having two or more radically polymerizable unsaturated groups in the molecule At least one compound selected from the group consisting of an oligomer or polymer having a (meth) acryloyl group in the chain and (e) a photopolymerization initiator are essential components, and if necessary, (d) the ( It contains (meth) acrylate compounds other than components a), (b) and (c). Each of these components may be used alone or in combination of two or more, and may further contain other components as long as the effects of the present invention are not impaired.
Hereinafter, each compound corresponding to the above (a) is referred to as “compound (a)”, and an aggregate of the compounds (a) (that is, a generic term of one or more compounds (a)) is referred to as “component (a)”. Call it. The above (b) to (e) are also referred to in the same manner.

In the said curable resin composition, as a content rate of (a), (b), (c) and (d) component, (a) 20-75 mass%, respectively with respect to 100 mass% of these total amounts, (B) 1-55 mass%, (c) 20-60 mass%, (d) 0-20 mass% are suitable. By setting in such a range, in addition to the properties that the obtained cured product is excellent in various physical properties such as transparency, residual film properties, and film thickness uniformity, the permanent deformation is sufficiently suppressed. Thus, the characteristics of excellent surface smoothness and remarkably small warpage can be sufficiently exhibited. If one of the above numerical ranges is not satisfied, these performances cannot be exhibited in a balanced manner at the same time, and when used in an optical recording medium, a highly reliable recording / reproducing function can be demonstrated over a long period of time. You may not be able to.

Moreover, in this invention, by containing each said component in the ratio mentioned above, the flowability of the said curable resin composition will become favorable, and the hardened | cured material (cured film) which is especially excellent in surface smoothness can be obtained suitably. It becomes possible. For example, when a cured film is obtained from a resin composition by a spin coating method, a flow mark of the resin composition may remain, resulting in a cured film having surface irregularities. However, in the present invention, the compatibility between the materials contained in the resin composition is improved by adopting the above configuration. In particular, by setting the content of the component (c) to be equal to or less than the above-described upper limit value, compatibility is improved, generation of flow marks is suppressed, and unevenness on the surface of the cured product is reduced. A cured product having high productivity and excellent surface smoothness can be obtained.

The content ratios of the components (a), (b), (c) and (d) are preferably (a) 25 to 75% by mass and (b) 5 to 50 with respect to the total amount of 100% by mass, respectively. Mass%, (c) 20-50 mass%, (d) 0-20 mass%. More preferably, they are (a) 25-70 mass%, (b) 5-50 mass%, (c) 20-50 mass%, (d) 0-20 mass%, respectively.

[(A) Component]
The compound (a) is a tri- or higher functional (meth) acrylate compound modified with alkylene oxide and / or ε-caprolactone. That is, a tri- or higher functional (meth) acrylate compound modified with alkylene oxide, a tri- or higher functional (meth) acrylate compound modified with ε-caprolactone, and a tri- or higher functional group modified with alkylene oxide and ε-caprolactone Any one or more of (meth) acrylate compounds. Such a compound is a (meth) acrylate obtained by modifying a polyhydric alcohol having 3 or more active hydrogens (a trihydric or higher polyhydric alcohol) with an alkylene oxide and / or ε-caprolactone, that is, a polyhydric or higher polyvalent. Examples include (meth) acrylic acid esters of compounds obtained by adding alkylene oxide and / or ε-caprolactone to alcohols, and (meth) acrylic acid esters of trivalent or higher alcohols having an alkylene oxide skeleton.

Examples of the trihydric or higher polyhydric alcohol include trimethylolpropane, glycerin, pentaerythritol, isocyanurate, ditrimethylolpropane, dipentaerythritol, and the like, which may have a substituent.

The alkylene oxide is preferably, for example, an alkylene oxide having 2 to 18 carbon atoms. More preferred are alkylene oxides having 2 to 8 carbon atoms, such as ethylene oxide, propylene oxide, butylene oxide, isobutylene oxide, 1-butene oxide, 2-butene oxide, trimethylethylene oxide, tetramethylene oxide, tetramethylethylene oxide, butadiene mono Examples thereof include oxide, octylene oxide, styrene oxide and the like. Among these, alkylene oxides having 2 to 4 carbon atoms such as ethylene oxide, propylene oxide, and butylene oxide are more preferable. Particularly preferred are ethylene oxide and propylene oxide.
In addition, the said alkylene oxide may be 1 type, and 2 or more types may be sufficient as it.

The number of alkylene oxides and / or ε-caprolactone present in the compound (a) (the number of repetitions) is 2 to 1 mol of the compound (a) as the average number of repetitions of the total amount of alkylene oxide and ε-caprolactone. It is suitable that it is 16 mol. As a result, the storage elastic modulus of the cured product can be adjusted more appropriately, and an optical recording medium having further excellent long-term storage stability can be provided. More preferably, it is 3-14 mol, Most preferably, it is 3-12 mol.

Specific examples of the compound (a) include tri (meth) acrylate of an alkylene oxide adduct of trimethylolpropane, tri (meth) acrylate of an ε-caprolactone adduct of trimethylolpropane, and an alkylene oxide adduct of glycerin. Tri (meth) acrylate, tri (meth) acrylate of glycerin ε-caprolactone adduct, tetra (meth) acrylate of pentaerythritol alkylene oxide adduct, tetra (meth) acrylate of pentaerythritol ε-caprolactone adduct, Examples include hexa (meth) acrylate of an alkylene oxide adduct of dipentaerythritol, hexa (meth) acrylate of an ε-caprolactone adduct of dipentaerythritol, and the like.

More preferably, the compound (a) is a compound obtained by using a polyhydric alcohol having a quaternary carbon (for example, trimethylolpropane, pentaerythritol, dipentaerythritol, etc.) as the polyhydric alcohol. This makes it possible to obtain a cured product that is further excellent in light resistance. Thus, the form in which the component (a) includes a (meth) acrylate compound obtained by modifying a trihydric or higher polyhydric alcohol having a quaternary carbon with an alkylene oxide and / or ε-caprolactone is also included in the present invention. This is a preferred form. Especially, it is more preferable that the ratio of the said (meth) acrylate compound which occupies for 100 mass% of total amount of the said (a) component is 50 mass% or more, More preferably, it is 70 mass% or more, Most preferably, it is 90 mass%. As described above, most preferably 100% by mass, that is, the component (a) is composed of only a (meth) acrylate compound obtained by modifying a trihydric or higher polyhydric alcohol having a quaternary carbon with alkylene oxide and / or ε-caprolactone. In addition, the curable resin composition does not contain a (meth) acrylate compound obtained by modifying a trihydric or higher polyhydric alcohol having a tertiary carbon with an alkylene oxide and / or ε-caprolactone. Is most preferred.

The compound (a) preferably has a molecular weight of 3000 or less. When it is 3000 or less, the compatibility between the materials contained in the resin composition is further improved, and a cured product that is superior in surface smoothness can be suitably obtained. More preferably, it is 2500 or less, More preferably, it is 2000 or less. Moreover, it is preferable that it is 200 or more, More preferably, it is 300 or more, More preferably, it is 400 or more.
Thus, although the form in which said (a) component contains a compound whose molecular weight is 3000 or less is also a suitable form of this invention, the said compound which occupies for the total amount of said (a) component 100 mass%. It is more preferable that the ratio is 50% by mass or more, whereby the compatibility between the materials is further improved, and a cured product having further excellent surface smoothness can be obtained. More preferably, it is 70 mass% or more, Especially preferably, it is 90 mass% or more, Most preferably, it is 100 mass%, That is, it is using only the compound whose molecular weight is 3000 or less as said (a) component.

[Regarding component (b)]
The compound (b) is a bifunctional (meth) acrylate compound modified with alkylene oxide and / or ε-caprolactone. That is, a bifunctional (meth) acrylate compound modified with alkylene oxide, a bifunctional (meth) acrylate compound modified with ε-caprolactone, and a bifunctional (meta) modified with alkylene oxide and ε-caprolactone. ) Any one or more of acrylate compounds. Such a compound is a (meth) acrylate obtained by modifying a polyhydric alcohol having two active hydrogens (dihydric alcohol) with alkylene oxide and / or ε-caprolactone, that is, dihydric alcohol with alkylene oxide and / or ε. -(Meth) acrylic acid ester of a compound to which caprolactone is added, (meth) acrylic acid ester of a dihydric alcohol having an alkylene oxide skeleton, and the like.

Examples of the dihydric alcohol and the dihydric alcohol having an alkylene oxide skeleton include (poly) ethylene glycol, (poly) propylene glycol, butanediol, neopentyl glycol, hexanediol, bisphenol A, S, and F. And may have a substituent. Further, it may be a dihydric alcohol having two or more alkylene oxide skeletons such as poly (ethylene-propylene) glycol.
The number of alkylene oxides and / or the presence of alkylene oxide and / or ε-caprolactone in the compound (b) is the same as described above for the compound (a).

Specific examples of the compound (b) include (poly) ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and the like. Ethylene glycol di (meth) acrylate; (poly) propylene glycol di (propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, etc. (Meth) acrylate; Diacrylate of alkylene oxide adduct of bisphenol A; Diacrylate of alkylene oxide adduct of neopentyl glycol; - diacrylate caprolactone adduct; of hydroxypivalic acid neopentyl glycol alkylene oxide adduct di (meth) acrylate; di (meth) acrylate of neopentyl glycol hydroxypivalate ε- caprolactone adduct.

[(C) Component]
The compound (c) is a compound other than the components (a) and (b) described above, and is a urethane (meth) acrylate compound or polyester (meta) having two or more radically polymerizable unsaturated groups in one molecule. ) Acrylate compound, epoxy (meth) acrylate compound, and at least one compound selected from the group consisting of an oligomer or polymer having a (meth) acryloyl group in the side chain. Among these, it is preferable to use at least a urethane (meth) acrylate compound because of excellent long-term storage stability. In addition, urethane (meth) acrylate compounds are preferable from the viewpoint of a wide design range of mechanical properties. Thus, the form in which the component (c) includes at least a urethane (meth) acrylate compound is also a preferred form of the present invention.
The urethane (meth) acrylate compound, the polyester (meth) acrylate compound, and the epoxy (meth) acrylate compound may be in any form of a monomer, an oligomer, or a polymer, but are preferably an oligomer or a polymer. .

The compound (c) also preferably has a number average molecular weight (Mn) of 500 or more, and preferably 10,000 or less. If it is 500 or more, the curing speed and the strength of the cured product will be more sufficient, and if it is 10000 or less, the wettability with the substrate, the mixing time when adjusting the resin composition, and the coating due to high viscosity It becomes more suitable in terms of workability at the time of construction, and further, for example, it is possible to more sufficiently reduce the warpage of a laminate obtained by applying and curing to a plastic substrate. Moreover, by being 10,000 or less, the compatibility of each material contained in a resin composition improves further, and it becomes possible to obtain the hardened | cured material excellent in surface smoothness suitably. The number average molecular weight is more preferably 1000 or more, further preferably 1500 or more, more preferably 8000 or less, and still more preferably 7000 or less.
Thus, although the form in which the said (c) component contains a compound whose molecular weight is 10,000 or less is also a suitable form of this invention, the said compound which occupies for the total amount of said (c) component 100 mass%. It is more preferable that the ratio is 50% by mass or more, whereby the compatibility between the materials is further improved, and a cured product having further excellent surface smoothness can be obtained. More preferably, it is 70 mass% or more, Especially preferably, it is 90 mass% or more, Most preferably, it is 100 mass%, That is, it is using only the compound whose molecular weight is 10,000 or less as said (c) component.

The compound (c) preferably further has a molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of 1 or more, and preferably 10 or less. When it is 1 or more, the conversion rate, the strength of the cured product, the mixing time of each component, and the like become more sufficient, and an optical recording medium can be obtained with higher productivity. The molecular weight distribution is more preferably in the range of 1 to 7, still more preferably 1 to 5.

In the present specification, the number average molecular weight (Mn), the weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) are obtained under the conditions of tetrahydrofuran (THF) as a mobile phase, a temperature of 40 ° C., and a flow rate of 0.3 mL / min. Thus, using a column TSK-gel SuperHM-H made by Tosoh Corporation and one TSK-gel SuperH2000, a gel permeation chromatography (GPC) apparatus made by Tosoh Corporation HLC-8220 GPC is a value converted to standard polystyrene. .

As the urethane (meth) acrylate compound, a compound obtained by a reaction of a polyhydric alcohol, an organic polyisocyanate, and a hydroxyl group-containing (meth) acrylate is preferably used. This reaction may be performed by a usual method. For example, it is preferable to use a tin-containing compound (for example, dibutyltin laurate, tin octenoate, etc.) as a catalyst for efficiently performing this reaction. In this case, from the viewpoint of reaction efficiency, it is also preferable to use another catalyst (for example, triethylenediamine) in combination.

The polyhydric alcohol may be either a saturated compound or an unsaturated compound. For example, ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl- Examples include 1,5-pentanediol, polyethylene glycol, polypropylene glycol, 1,4-dimethylolbenzene, glycerin, trimethylolpropane, pentaerythritol, polytetramethylene glycol, polyester polyol, polycaprolactone polyol, and the like. Methylene glycol is preferred.

Examples of the organic polyisocyanate include tolylene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate. Among them, isophorone diisocyanate is preferable.
Examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, and the like.

As the polyester (meth) acrylate compound, a compound obtained by a reaction of a polybasic acid or an anhydride acid thereof, a polyhydric alcohol and (meth) acrylic acid is preferably used. Just do it.
The polybasic acid or its anhydride acid may be either a saturated compound or an unsaturated compound, such as maleic acid, succinic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, etc. In addition, these anhydride acids are mentioned.
About the said polyhydric alcohol, the compound etc. which were mentioned above are mentioned.

The epoxy (meth) acrylate compound is an epoxy poly (meth) acrylate obtained by a reaction between an epoxy resin and (meth) acrylic acid, or a carboxyl obtained by a reaction between the epoxy (meth) acrylate and a polybasic acid anhydride. Although acid-modified epoxy (meth) acrylate is preferably used, this reaction may be performed by a usual method.
Examples of the epoxy resin include phenol novolac epoxy resin, cresol novolac epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, trisphenol methane type epoxy resin, polybutanediene modified epoxy resin, alicyclic epoxy resin, Examples thereof include brominated phenol novolac epoxy resins, brominated bisphenol A type epoxy resins, amino group-containing epoxy resins and the like.
Examples of the polybasic acid anhydride include maleic anhydride, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and the like.

The oligomer or polymer having a (meth) acryloyl group in the side chain is particularly an oligomer or polymer having a (meth) acryloyl group in the side chain and two or more radically polymerizable unsaturated groups in the molecule. Although not limited, for example, following formula (1):

(Wherein R ¹ is the same or different and represents an alkylene group having 2 to 8 carbon atoms; R ² represents a hydrogen atom or a methyl group; m is a positive integer). A vinyl-based polymer having a repeating unit is suitable, whereby the hardness of the cured product can be further improved.

In the above formula (1), examples of the alkylene group having 2 to 8 carbon atoms represented by R ¹ include an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, and a heptamethylene group. , Octamethylene group, cyclohexylene group, 1,4-dimethylcyclohexane-α, α′-diyl group, 1,3-dimethylcyclohexane-α, α′-diyl group, 1,2-dimethylcyclohexane-α, α ′ -Diyl group, 1,4-dimethylphenyl-α, α'-diyl group, 1,3-dimethylphenyl-α, α'-diyl group, 1,2-dimethylphenyl-α, α'-diyl group, etc. Can be mentioned. In addition, although there are m substituents represented by R ¹ in the above formula (1), they may be the same or different.

In said formula (1), m represents the average addition mole number of the oxyalkylene group represented by R < ¹ > O, and is a positive integer. Preferably it is an integer of 1-20, More preferably, it is an integer of 1-10, More preferably, it is an integer of 1-5.
In addition, although the number of the repeating units represented by the said Formula (1) should just be a positive integer, it is suitable that it is an integer of 5-600. More preferably, it is an integer of 20 to 300, and further preferably an integer of 40 to 200.

The vinyl polymer represented by the above formula (1) can also be obtained as a liquid viscous material except in the case of a polymer having a high solid monomer content. If it is a liquid viscous body, since the solubility to a (meth) acrylate type monomer etc. is good, the improvement of work efficiency can be aimed at when adjusting a resin composition.
The vinyl polymer represented by the above formula (1) is, for example, the following formula (2):

(Wherein R ¹ , R ² and m have the same meanings as those in the above formula (1), respectively) or a vinyl monomer (also referred to as “heterogeneous polymerizable monomer”) or It can be prepared by a normal cationic polymerization technique using two or more kinds. Moreover, it can also prepare easily by carrying out living cation polymerization by the method described in Unexamined-Japanese-Patent No. 2006-241189 using 1 type, or 2 or more types of this vinyl-type monomer. When two or more vinyl monomers represented by the above formula (2) are used in combination, the resulting copolymer is a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer. Either a polymer or a combination thereof, or a graft copolymer may be used.

Specific examples of the vinyl monomer represented by the above formula (2) include the following compounds.
(Meth) acrylic acid 2-vinyloxyethyl, (meth) acrylic acid 3-vinyloxypropyl, (meth) acrylic acid 2-vinyloxypropyl, (meth) acrylic acid 1-vinyloxypropyl, (meth) acrylic acid 1-methyl 2-vinyloxyethyl, 4-vinyloxybutyl (meth) acrylate, 3-vinyloxybutyl (meth) acrylate, 2-vinyloxybutyl (meth) acrylate, 1-methyl-3-vinyloxypropyl (meth) acrylate, (meth) 2-methyl-3-vinyloxypropyl acrylate, 1-methyl-2-vinyloxypropyl (meth) acrylate, 1,1-dimethyl-2-vinyloxyethyl (meth) acrylate, 6-vinyl (meth) acrylate Roxyhexyl, (meth) acrylic acid 4-vinyloxycyclohexyl, (meth) acrylic acid -Vinyloxymethylcyclohexylmethyl, (meth) acrylic acid 3-vinyloxymethylcyclohexylmethyl, (meth) acrylic acid 2-vinyloxymethylcyclohexylmethyl, (meth) acrylic acid 4-vinyloxymethylphenylmethyl, (meth) acrylic 3-vinyloxymethylphenylmethyl acid, 2-vinyloxymethylphenylmethyl (meth) acrylate,

2- (2-vinyloxyethoxy) ethyl (meth) acrylate, 2- (2-vinyloxyisopropoxy) ethyl (meth) acrylate, 2- (2-vinyloxyethoxy) propyl (meth) acrylate, ( 2- (2-vinyloxyisopropoxy) propyl (meth) acrylate, 2- (2-vinyloxyethoxy) isopropyl (meth) acrylate, 2- (2-vinyloxyisopropoxy) isopropyl (meth) acrylate, ( 2- (2- (2-vinyloxyethoxy) ethoxy} ethyl (meth) acrylate, 2- {2- (2-vinyloxyisopropoxy) ethoxy} ethyl (meth) acrylate, 2-{(meth) acrylic acid 2- (2-vinyloxyisopropoxy) isopropoxy} ethyl, (meth) acrylic acid 2- {2- (2-vinyloxyethoxy) ethoxy Propyl, 2- (2- (2-vinyloxyethoxy) isopropoxy} propyl (meth) acrylate, 2- {2- (2-vinyloxyisopropoxy) ethoxy} propyl (meth) acrylate, (meth) acryl Acid 2- {2- (2-vinyloxyisopropoxy) isopropoxy} propyl, (meth) acrylic acid 2- {2- (2-vinyloxyethoxy) ethoxy} isopropyl, (meth) acrylic acid 2- {2- (2-vinyloxyethoxy) isopropoxy} isopropyl, (meth) acrylic acid 2- {2- (2-vinyloxyisopropoxy) ethoxy} isopropyl, (meth) acrylic acid 2- {2- (2-vinyloxyiso) Propoxy) isopropoxy} isopropyl, (meth) acrylic acid 2- [2- {2- (2-vinyloxyethoxy) ethoxy} Xyl] ethyl, 2- (2- {2- (2-vinyloxyisopropoxy) ethoxy} ethoxy] ethyl (meth) acrylate, 2- (2- [2- {2- (2- Vinyloxyethoxy) ethoxy} ethoxy] ethoxy) ethyl.

Among these vinyl monomers, 2-vinyloxyethyl (meth) acrylate, 3-vinyloxyethyl (meth) acrylate, 2-vinyloxypropyl (meth) acrylate, 1-methyl-2- (meth) acrylate Vinyloxyethyl, 4-vinyloxybutyl (meth) acrylate, 6-vinyloxyhexyl (meth) acrylate, 4-vinyloxycyclohexyl (meth) acrylate, 4-vinyloxymethylcyclohexylmethyl (meth) acrylate, (meth) acryl 2- (2-vinyloxyethoxy) ethyl acid, 2- (2-vinyloxyisopropoxy) propyl (meth) acrylate, 2- {2- (2-vinyloxyethoxy) ethoxy} ethyl (meth) acrylate Is preferred.

The vinyl polymer represented by the above formula (1) may also be a copolymer having a structural unit derived from a monomer capable of cationic polymerization. Such a copolymer can be easily prepared by cationic polymerization or living cationic polymerization of a vinyl monomer represented by the above formula (2) and a cationically polymerizable monomer. In this case, each monomer may be used alone or in combination of two or more, and the copolymer obtained is a random copolymer, an alternating copolymer, a periodic copolymer, a block copolymer or its copolymer. Any of the combinations may be used, and a graft copolymer may be used.

Examples of the monomer capable of cationic polymerization include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, octadecyl vinyl ether, 2 -Vinyl ether compounds such as chloroethyl vinyl ether, 4-hydroxybutyl vinyl ether, dihydrofuran; styrene, 4-methylstyrene, 3-methylstyrene, 2-methylstyrene, 2,5-dimethylstyrene, 2,4-dimethylstyrene, 2 , 4,6-trimethylstyrene, 4-t-butylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 4 Styrene derivatives such as methoxystyrene and 4-chloromethylstyrene; N-vinyl compounds such as N-vinylcarbazole and N-vinylpyrrolidone; divinyl compounds such as isopropenylstyrene, 2-vinyloxyethyl cinnamate and 2-vinyloxyethyl sorbate; A trivinyl compound etc. are mentioned. Among these, vinyl ether compounds such as isobutyl vinyl ether, cyclohexyl vinyl ether, dihydrofuran, and 2-ethylhexyl vinyl ether are preferable.

When polymerizing a vinyl monomer represented by the above formula (2) and a monomer capable of cationic polymerization, these molar ratios (monomer capable of cationic polymerization / vinyl monomer represented by the above formula (2)) Is preferably in the range of 0.1-10. By adjusting to such a range, it is possible to obtain a copolymer having a high crosslink density of the cured product, excellent surface hardness, and little cure shrinkage. More preferably, it is 0.5-8, More preferably, it is 0.8-5.

The vinyl monomer represented by the above formula (2) has a radically polymerizable or anionically polymerizable (meth) acryloyl group and a cationically polymerizable vinyl ether group at the same time, so the polymerization method should be selected. Thus, a polymer having a (meth) acryloyl group or a vinyl ether group as a pendant group can be obtained. Therefore, by subjecting the vinyl ether group of the vinyl monomer represented by the above formula (2) to cation polymerization or living cation polymerization alone or together with a monomer capable of cation polymerization, a (meth) acryloyl group is formed. A vinyl polymer represented by the above formula (1) having a pendant group can be obtained.

The compound (c) is also preferably a single cured product having a storage elastic modulus at 25 ° C. of 1 to 300 MPa. By using such a compound (c), in the cured product obtained from the curable resin composition of the present invention, permanent deformation due to pressure marks, dents, etc. is more sufficiently suppressed, and warpage of the cured product is suppressed. More fully reduced. More preferably, it is 3 MPa or more, More preferably, it is 10 MPa or more, More preferably, it is 200 MPa or less, More preferably, it is 100 MPa or less, Most preferably, it is 50 MPa or less.
The storage elastic modulus at 25 ° C. here is a value determined by a dynamic viscoelasticity measurement method under the following measurement conditions for a cured product obtained by curing the compound (c) alone.
<Measurement conditions>
The dynamic viscoelasticity is measured under the conditions of a tensile mode, a frequency of 1 Hz, a clamp distance of 25 mm, an amplitude of 0.1%, and a heating rate of 5 ° C./min.

As described above, the component (c) preferably contains a compound having a single cured product having a storage elastic modulus at 25 ° C. of 1 to 300 MPa, and such a form is also a preferred form of the present invention. It is one of. That is, the component (c) includes a urethane (meth) acrylate compound, a polyester (meth) acrylate compound, an epoxy (meth) acrylate compound, and a side chain having two or more radically polymerizable unsaturated groups in the molecule ( It is at least one compound selected from the group consisting of an oligomer or polymer having a (meth) acryloyl group, and contains a compound having a single cured product having a storage elastic modulus at 25 ° C. of 10 to 900 MPa. preferable. This makes it possible to more fully demonstrate the effects of the present invention. Among them, the component (c) is composed of only a compound having a storage elastic modulus of 1 to 300 MPa at 25 ° C. of the single cured product, that is, the component (c) is a single cured product at 25 ° C. More preferably, it is composed of one or more compounds having a storage modulus of 1 to 300 MPa.

Further, the compound (c) is preferably such that the glass transition temperature (also referred to as “Tg”) of a single cured product is −50 to 50 ° C. By using the compound (c) having a Tg of −50 ° C. or higher, permanent deformation due to pressure marks or dents can be more sufficiently suppressed in the cured product obtained from the curable resin composition of the present invention, Moreover, the curvature of the said hardened | cured material is more fully reduced as it is 50 degrees C or less. More preferably, it is -45 degreeC or more, More preferably, it is -40 degreeC or more, More preferably, it is 40 degreeC or less, More preferably, it is 30 degreeC or less, Most preferably, it is 20 degreeC or less.
The glass transition temperature here is a value determined by a dynamic viscoelasticity measurement method under the same measurement conditions as the storage elastic modulus (25 ° C.) of the cured product obtained by curing the above-described compound (c) alone. And the temperature of the maximum tan δ value is adopted.

[About component (d)]
The compound (d) is a (meth) acrylate compound other than the components (a), (b) and (c), and may be included in the curable resin composition of the present invention as necessary. Such a compound (d) is preferably a compound that can be co-cured with any one or more of the components (a), (b), and (c), and is in the form of a monomer (monomer). Is preferred. By including a compound (d), there exists an effect that the liquid viscosity and the physical property of hardened | cured material can be adjusted, for example. The compound (d) may be one type of compound or two or more types.

Examples of the compound (d) include the vinyl monomer represented by the general formula (2), a (meth) acrylate compound not modified with alkylene oxide or ε-caprolactone, and a monofunctional (meth). An acrylate compound etc. are mentioned. Specifically, 1 type (s) or 2 or more types, such as a vinyl-type monomer represented with General formula (2) mentioned above, and the following compound, are mentioned.
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) Acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, Methoxydiethylene glycol (meth) acrylate, butoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, trif Monofunctional (meth) acrylate compounds such as oloethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and dicyclopentanyl (meth) acrylate ;

1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 2 -Butyl-2-ethyl-1,3-propanediol di (meth) acrylate, dimethylol-tricyclodecane di (meth) acrylate, pentacyclopentadecane dimethanol di (meth) acrylate, di (meta) of bisphenol A diglycidyl ether ) Acrylic acid adduct, cyclohexanedimethanol di (meth) acrylate, norbornane dimethanol di (meth) acrylate, p-menthane-1,8-diol di (meth) acrylate, p-menthane-2,8-diol di (meth) acrylate , P-men -3,8-diol di (meth) acrylate, bicyclo [2.2.2] -octane-1-methyl-4-isopropyl-5,6-dimethylol di (meth) acrylate, bis ((meth) acryloxyneopentyl Glycol) adipate, bifunctional (meth) acrylate compounds such as tricyclodecane di (meth) acrylate;

Trifunctional or higher (meth) such as trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate (Meth) acrylic acid derivatives such as acrylate compounds;

Methoxyethyl (meth) acrylate, 2-methoxy-2-methylethyl (meth) acrylate, 2-methoxy-1-methylethyl (meth) acrylate, ethoxyethyl (meth) acrylate, 2-ethoxy-2-methylethyl (meth) ) Acrylate, 2-ethoxy-1-methylethyl (meth) acrylate, propoxyethyl (meth) acrylate, propoxypropyl (meth) acrylate, isopropoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, etc. (Meth) acrylic derivatives;

4- (meth) acryloyloxymethyl-2-methyl-2-ethyl-1,3-dioxolane, 4- (meth) acryloyloxymethyl-2-methyl-2-isobutyl-1,3-dioxolane, 4- (meth) ) 1,3-dioxolane-based monomers such as acryloyloxymethyl-2-cyclohexyl-1,3-dioxolane, 4- (meth) acryloyloxymethyl-2,2-dimethyl-1,3-dioxolane, and the like.

The compound (d) is also preferably a vinyl monomer (heteropolymerizable monomer) represented by the general formula (2) from the viewpoint of good adhesion to a commonly used polypolycarbonate substrate. Can be used for Among them, 2-vinyloxyethyl (meth) acrylate, 3-vinyloxyethyl (meth) acrylate, 2-vinyloxypropyl (meth) acrylate, 1-methyl-2-vinyloxyethyl (meth) acrylate, (meth) acrylic acid 4 -Vinyloxybutyl, 6-vinyloxyhexyl (meth) acrylate, 4-vinyloxycyclohexyl (meth) acrylate, 4-vinyloxymethylcyclohexylmethyl (meth) acrylate, 2- (2-vinyloxy) (meth) acrylate Ethoxy) ethyl, 2- (2-vinyloxyisopropoxy) propyl (meth) acrylate, and 2- {2- (2-vinyloxyethoxy) ethoxy} ethyl (meth) acrylate are preferred. Of these, 2- (2-vinyloxyethoxy) ethyl (meth) acrylate is preferable.

The compound (d) is particularly preferably a bifunctional or higher-functional (meth) acrylate compound (that is, a polyfunctional (meth) acrylate compound) or a vinyl monomer represented by the general formula (2) (heterogeneous polymerizable). Monomer).

The components (a), (b), (c) and (d) are also preferably used so that the average acrylic equivalent to the total amount thereof is 200 or more. Thereby, the warp of the optical recording medium is further reduced, and the operational effects of the present invention can be more fully exhibited. More preferably, it is 205 or more. Moreover, it is suitable that it is 400 or less, and thereby, it is possible to further suppress the formation of dents or the like in the optical recording medium, and to further sufficiently exhibit long-term storage stability. More preferably, it is 390 or less, More preferably, it is 380 or less.
In the present invention, the acrylic equivalent is 200 or more, and the glass transition temperature (Tg) of the cured product obtained by curing the curable resin composition, the loss tangent tan δ at Tg and the storage elastic modulus. However, when it is within a preferable range described later, it is possible to provide an optical recording medium having further excellent warpage characteristics. In particular, within each preferred range, the smaller the Tg or storage modulus, and the greater the acrylic equivalent or loss tangent tan δ, the better the trend.

The average acrylic equivalent to the total amount of the above components (a), (b), (c) and (d) is determined by the sum of Mx × Ax ÷ A.
Mx is the molecular weight (*) of (meth) acrylic acid ester ((meth) acrylate) x corresponding to the above components (a), (b), (c) and (d), and (meth) acrylic acid When the ester x has one (meth) acryloyl group, the molecular weight value of the (meth) acrylic ester x is “Mx”. When there are two or more (meth) acryloyl groups, the molecular weight of (meth) acrylic acid ester x divided by the number of (meth) acryloyl groups is “Mx”.
Ax is the mass (part by mass) of the (meth) acrylic ester x.
A is the sum total (parts by mass) of the total amount of all the components (a), (b), (c) and (d) contained in the resin composition.
* As the molecular weight here, for the components (a), (b) and (d), the value calculated as the sum of the atomic weights of the constituent elements is adopted. For the component (c), the number average molecular weight (Mn) is adopted.

The components (a), (b), (c) and (d) are also preferably such that the total amount of compounds having a molecular weight (*) of 1500 or more is 70% by mass or less with respect to the total amount of 100% by mass. It is. Thereby, since the compatibility of each material contained in the resin composition is further improved, it becomes possible to obtain a cured product that is more excellent in surface smoothness. More preferably, it is 65 mass% or less, More preferably, it is less than 65 mass%.
* As the molecular weight here, for the components (a), (b) and (d), the value calculated as the sum of the atomic weights of the constituent elements is adopted. For the component (c), the number average molecular weight (Mn) is adopted.

[Other polymerizable components]
In the present invention, in addition to the above-described essential components (a) to (c) and an optional component (d) contained as necessary, other co-curable components (other polymerizable properties) may be added as necessary. As the component), one or more of the following unsaturated compounds may be contained.
Styrene monomers such as styrene, vinyltoluene, 4-t-butylstyrene, α-methylstyrene, 4-chlorostyrene, 4-methylstyrene, 4-chloromethylstyrene, divinylbenzene; diallyl phthalate, diallyl isophthalate, cyanuric Allyl ester monomers such as triallyl acid and triallyl isocyanurate; vinyl ether monomers such as triethylene glycol divinyl ether, cyclohexane dimethanol divinyl ether, hydroxybutyl vinyl ether, dodecyl vinyl ether; trimethylolpropane diallyl ether, pentaerythritol triallyl ether, allyl Glycidyl ether, allyl ether of methylol melamine, adipic acid ester of glyceryl diallyl ether, allyl acetal Allyl ether monomers such as allyl ether of methylol glyoxalurein; maleic acid ester monomers such as diethyl maleate and dibutyl maleate; Fumarate monomers such as dibutyl fumarate and dioctyl fumarate; (meth) acryloylmorpholine; N-vinylformamide; N-vinylpyrrolidone and the like.

The content ratio of these unsaturated compounds is preferably 0 to 30% by mass with respect to 100% by mass of the total amount of the components (a) to (d) and the unsaturated compound. However, considering the recyclability of the resin composition when the curable resin composition is subjected to a spin coating method, for example, the lower the content of the unsaturated compound, the better. More preferably, it is 20 mass% or less, More preferably, it is 10 mass% or less, Most preferably, it is substantially free of these unsaturated compounds.
Hereinafter, the components (a) to (d) and the unsaturated compound are collectively referred to as “polymerizable component”. That is, the polymerizable component is composed of the above components (a) to (c) (in the case of further including (d) component, the above (a) to (d) component), and may further include the above unsaturated compound. It is. In other words, when the curable resin composition for an optical recording medium of the present invention does not contain the unsaturated compound, the components (a) to (c) (when the component (d) is further included, the component (a) To (d) component), and when the unsaturated compound is included, the components (a) to (c) (or (d) when the component (a) to (d) are included) ) And the unsaturated compound.

[Regarding component (e)]
The resin composition of the present invention also contains a photopolymerization initiator (e) as an essential component, but by containing the photopolymerization initiator, there is an effect that it can be quickly cured by light irradiation. As the photopolymerization initiator (e), a photo radical polymerization initiator that generates a polymerization initiating radical upon irradiation with light and a photo cationic polymerization initiator that generates a polymerization initiating cation upon irradiation with light are suitable. Species or two or more can be used.

Examples of the photo radical polymerization initiator include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy -2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4 -Morpholinophenyl) butanone, oligo {2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone}, 2-hydroxy-1- {4- [4- (2-hydroxy-2) Acetophenones such as -methylpionyl) benzyl] phenyl} -2-methylpropan-1-one Benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyl-diphenyl sulfide, 3, 3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyl) Benzophenones such as (oxy) ethyl] benzenemethananium bromide, (4-benzoylbenzyl) trimethylammonium chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthio Thioxanthones such as xanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy) -3,4-dimethyl-9H-thioxanthone-9-one mesochloride Etc.

Among the radical photopolymerization initiators, acetophenones are preferable. Specifically, 1-hydroxycyclohexyl phenyl ketone, oligo {2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] Propanone}, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropane -1-one is preferred. Among them, oligo {2-hydroxy-2-methyl-1- is preferable because it improves the durability of an optical disk using the curable resin composition for an optical disk as a protective layer and suppresses an increase in warpage during a heat resistance test. [4- (1-methylvinyl) phenyl] propanone} is particularly preferred.

Examples of the photocationic polymerization initiator include arylsulfonium salts such as triphenylsulfonium hexafluorophosphate and triphenylsulfonium hexafluoroantimonate; diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluorophosphate, and (tricumyl) iodonium. Examples include aryliodonium salts such as tetrakis (pentafluorophenyl) borate; aryldiazonium salts such as phenyldiazonium tetrafluoroborate. Of these, arylsulfonium salts and diazonium salts are preferable, and (trilcumyl) iodonium tetrakis (pentafluorophenyl) borate is particularly preferable.

In the curable resin composition, the content of the photopolymerization initiator (e) is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the total amount of the polymerizable components. When it is 1 part by weight or more, the curable resin composition can be cured more fully, and when it is 10 parts by weight or less, odor generation and coloring of the cured product can be sufficiently suppressed, and the curable resin composition The recyclability of the product and the long-term storage stability of the cured product can be further improved. More preferably, it is 1-5 weight part, More preferably, it is 1-3 weight part.

[Other ingredients]
The curable resin composition of the present invention may further contain an ultraviolet absorber and a thermal polymerization initiator. In the case where the ultraviolet absorber is included, it is possible to enhance the recyclability of the resin composition, to sufficiently exhibit the effects of adjusting the curing speed and reducing the warpage of the optical disk. When the thermal polymerization initiator is included, the heat generated when the resin composition is cured with ultraviolet rays is utilized, and the effect of further curing can be achieved.

Examples of the ultraviolet absorber include benzotriazole ultraviolet absorbers, hydroxyphenyltriazine ultraviolet absorbers, benzophenone ultraviolet absorbers, salicylic acid ultraviolet absorbers, and inorganic oxide ultraviolet absorbers. Or 2 or more types can be used. Specifically, phenyl salicylate, (2,2′-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxybenzophenone, glycol salicylate, t-butylmethoxydibenzoylmethane, ethylhexyl methoxycinnamate, dimethyl PABA ( para-aminobenzoic acid) octyl, dimethyl PABA ethylhexyl, etc., for example, 2- (2-hydroxy-5-t-butylphenyl) -2H-benzotriazole (trade name “TINUBIN PS”, Ciba Specialty Chemicals) 2- {2-hydroxy-4- (1-octyloxycarbonylethoxy) phenyl} -4,6-bis (4-phenylphenyl) -1,3,5-triazine (trade name “TINUBIN 479”, Ciba Specialty Chemical 2- {2-hydroxy-5- (2-methacryloyloxyethyl) phenyl} benzotriazole (trade name “RUVA93”, manufactured by Otsuka Chemical Co., Ltd.), octyl-3- {3-t-butyl-4- Hydroxy-5- (5-chloro-2H-benzotriazole-2-yl) phenyl} propionic acid 2-ethylhexyl-3- {3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzo Triazole-2-yl) phenyl} propionic acid (trade name “TINUBIN 109”, manufactured by Ciba Specialty Chemicals) is preferably used.

The addition amount of the ultraviolet absorber is preferably 0.03 to 2 parts by weight with respect to 100 parts by weight of the total amount of the polymerizable components. More preferably, it is 0.05-1 weight part, More preferably, it is 0.05-0.5 weight part.

As the thermal polymerization initiator, a thermal radical polymerization initiator that generates a polymerization initiating radical by heating and a thermal cationic polymerization initiator that generates a polymerization initiating cation by heating are suitable.
Examples of the thermal radical polymerization initiator include the following organic peroxide initiators and azo initiators, and one or more of these can be used.
Methyl ethyl ketone peroxide, cyclohexanone peroxide, methyl cyclohexanone peroxide, methyl acetoacetate peroxide, acetyl acetate peroxide, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) ) -Cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1-bis (t- Butylperoxy) -cyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, 1,1-bis (t-butylperoxy) butane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) ) Propane, p- Tantalum hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroperoxide, t-butyl hydroperoxide, α, α′-bis (t-butylperoxy) ) Diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5 Bis (t-butylperoxy) hexyne-3, isobutyryl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, succinic acid peroxide, m-toluo Ylbenzoyl peroxide, benzoyl peroxide, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethoxyhexyl Peroxydicarbonate, di-3-methoxybutylperoxydicarbonate, di-s-butylperoxydicarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, α, α'-bis (neodecanoylperoxy) Diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxysopropyl monocarbonate, t-butylperoxysobutyrate, t-butylperoxymalate, t-butylperoxy-3,5,5-trimethylhexanoate Ate, t-butylperoxylaure , T-butylperoxysopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-butylperoxyacetate, t-butylperoxy-m-toluylbenzoate, t-butylperoxybenzoate, bis (t-butyl Peroxy) isophthalate, 2,5-dimethyl-2,5-bis (m-toluylperoxy) hexane, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butyl Organic peroxides such as peroxyallyl monocarbonate, t-butyltrimethylsilyl peroxide, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 2,3-dimethyl-2,3-diphenylbutane An initiator;

2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 1-[(1-cyano-1-methylethyl) azo] formamide, 1,1′-azobis (cyclohexane-1-carbonitrile), 2, 2'-azobis (2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2, 4-dimethyl-4-methoxyvaleronitrile), 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis (2-methyl-N-phenylpropionamidine) dihydrochloride, 2 , 2′-azobis [N- (4-chlorophenyl) -2-methylpropionamidine] dihydrochloride, 2,2′-azobis [N- (4-hydrophenyl) -2-methyl Propionamidine] dihydrochloride, 2,2′-azobis [2-methyl-N- (phenylmethyl) propionamidine] dihydrochloride, 2,2′-azobis [2-methyl-N- (2-propenyl) propion Amidine] dihydrochloride, 2,2′-azobis [N- (2-hydroxyethyl) -2-methylpropionamidine] dihydrochloride, 2,2′-azobis [2- (5-methyl-2-imidazoline- 2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2 ″ -azobis [2- (4,5,6) , 7-Tetrahydro-1H-1,3-diazepin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] Dihydrochloride, 2, 2 -Azobis [2- (5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis {2- [1- (2-hydroxyethyl)- 2-Imidazolin-2-yl] propane} dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis {2-methyl-N- [1 , 1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide}, 2,2 '-Azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2'-azobis (2-methylpropionamide), 2,2'-azobis (2,4,4-trimethylpentane) ), 2,2′-azobis (2-methylpropane), 2,2′-azobis (2-methylpropionic acid) dimethyl, 4,4′-azobis (4-cyanopentanoic acid), 2,2′-azobis An azo initiator such as [2- (hydroxymethyl) propionitrile].

Among these thermal radical initiators, radicals are efficiently generated by the catalytic action of metal soaps and / or amine compounds such as methyl ethyl ketone peroxide, cyclohexanone peroxide, cumene hydroperoxide, t-butylperoxybenzoate, and benzoyl peroxide. And 2,2′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile) are preferable.

Examples of the thermal cationic polymerization initiator include the following compounds, and one or more of them can be used.
Lewis acid (eg, boron trifluoride, titanium chloride, titanium chloride, ferrous chloride, ferric chloride, zinc chloride, zinc bromide, stannous chloride, stannic chloride, bromide Stannous, stannic bromide, dibutylstannic dichloride, dibutylstannic dibromide, tetraethyltin, tetrabutyltin, triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, etc.) and electron donating compounds ( For example, complexes with N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, hexamethylphosphoric triamide, dimethyl sulfoxide, trimethyl phosphate, triethyl phosphate, etc .; proton acids (for example, halogenocarbons) Acids, sulfonic acids, sulfuric monoesters, phosphoric monoesters, phosphoric diesters, polyphosphorus Esters, boric acid monoesters, boric acid diesters, etc.) bases (eg, ammonia, monoethylamine, diethylamine, triethylamine, pyridine, piperidine, aniline, morpholine, cyclohexylamine, monoethanolamine, diethanolamine, triethanolamine, Compound neutralized with butylamine). Among these, amine complexes of various proton acids are preferable because the pot life can be easily adjusted.

Here, in the case of using the thermal radical polymerization initiator, in order to lower the decomposition temperature of the thermal radical polymerization initiator, thermal polymerization that can effectively generate radicals by promoting the decomposition of the thermal polymerization initiator Accelerators can be used.
Examples of the thermal polymerization accelerator include metal soaps such as cobalt, copper, tin, zinc, manganese, iron, zirconium, chromium, vanadium, calcium, and potassium, primary, secondary, tertiary amine compounds, and quaternary. An ammonium salt, a thiourea compound, a ketone compound, etc. are mentioned, These 1 type (s) or 2 or more types can be used. Among them, cobalt octylate, cobalt naphthenate, copper octylate, copper naphthenate, manganese octylate, manganese naphthenate, dimethylaniline, trietalamine, triethylbenzylammonium chloride, di (2-hydroxyethyl) p-toluidine, ethylenethio Urea, acetylacetone and methyl acetoacetate are preferred.
The blending amount of the thermal polymerization accelerator is preferably 0.001 to 10 parts by weight with respect to 100 parts by weight of the total amount of the polymerizable components. When the blending amount of the thermal polymerization accelerator is within such a range, it is preferable in terms of curability of the resin composition, physical properties of the cured product, and economical efficiency. More preferably, it is 0.01-5 weight part, More preferably, it is 0.05-3 weight part.

In the curable resin composition, one or more of a photosensitizer, a photopolymerization accelerator, metal oxide particles, a surface function modifier, a solvent, and the like can be used as necessary.
The photosensitizer is one that can transfer excitation energy from an excited state generated by photoexcitation to a photopolymerization initiator and promote the decomposition of the photopolymerization initiator to effectively generate radicals. One or more of 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone and the like can be used.
0.05-20 weight part is suitable for the compounding quantity of the said photosensitizer with respect to 100 weight part of total amounts of the said polymeric component. If the compounding quantity of a photosensitizer is in such a range, it is preferable at the point of sclerosis | hardenability of a resin composition, the physical property of hardened | cured material, and economical efficiency. More preferably, it is 0.1-15 weight part, More preferably, it is 0.2-10 weight part.

The photopolymerization accelerator is an agent that can promote the decomposition of the photopolymerization initiator and effectively generate radicals. For example, triethanolamine, methyldiethanolamine, triisopropanolamine, 4-dimethylaminobenzoic acid. Methyl, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-dimethylaminobenzoate-2-n-butoxyethyl, 2-dimethylaminoethyl benzoate, N, N-dimethylparatoluidine, 4, 1 type (s) or 2 or more types, such as 4'- dimethylamino benzophenone and 4,4'- diethylamino benzophenone, can be used. Of these, triethanolamine, methyldiethanolamine, and triisopropanolamine are preferable.
The blending amount of the photopolymerization accelerator is preferably 0.05 to 20 parts by weight with respect to 100 parts by weight of the total amount of the polymerizable components. When the blending amount of the photopolymerization accelerator is within such a range, it is preferable in terms of curability of the resin composition, physical properties of the cured product, and economical efficiency. More preferably, it is 0.1-15 weight part, More preferably, it is 0.2-10 weight part.

The metal oxide particles mean particles made of a metal oxide, preferably fine particles made of a metal oxide. In the case of containing such metal oxide particles, the hardness of the cured product formed from the resin composition is improved, and it is less likely to be damaged, and it is advantageous in that a low-reflective coating film can be obtained. It is.
The metal oxide constituting the particles is preferably an oxide containing at least one metal element selected from the group consisting of Si, Ti, Zr, Zn, Sn, In, La, and Y. The metal oxide may be a single oxide containing these elements or a complex oxide containing these elements.
Specific examples of the metal oxides constituting the particles, for _{example, SiO, SiO 2, TiO 2} , ZrO 2, ZnO, In 2 O 3, La 2 O 3, Y 2 O 3, SiO 2 -Al 2 O ₃ , SiO ₂ —Zr ₂ O ₃ , SiO ₂ —Ti ₂ O ₃ , Al ₂ O ₃ —ZrO ₂ , TiO ₂ —ZrO _2, etc., and one or more of these can be used. Of these, SiO ₂ , TiO ₂ , ZrO ₂ , and ZnO ₂ are preferable.

The average particle diameter of the metal oxide particles is preferably 1 to 300 nm. If it exceeds 300 nm, the cured product may not have sufficient transparency. More preferably, it is 1-300 nm, More preferably, it is 1-50 nm.
In addition, the average particle diameter of a particle here means the volume average particle diameter calculated | required by measuring using a dynamic light scattering type particle size distribution measuring apparatus.
The compounding amount of the metal oxide particles is preferably 0 to 80 parts by weight with respect to 100 parts by weight of the total amount of the polymerizable components. If it exceeds 80 parts by weight, the cured product may be brittle. More preferably, it is 0-50 weight part.

The anti-fingerprint removal property is improved by containing the surface function adjusting agent, but as the surface function adjusting agent, a fluorine-based compound or a silicone-based compound is generally used. In the present invention, for example, a polyether-modified fluorine-based compound, a polyether-modified fluorine-based compound having a reactive group (for example, (meth) acrylate), a non-reactive silicone, and a reactive (for example, (meth) acrylate) Any of silicone, polymer silicone, and macromonomer silicone can be used.

The above-mentioned solvent means a so-called organic solvent having volatility or a low boiling point, for example, an aromatic hydrocarbon such as benzene, toluene and chlorobenzene; an aliphatic or alicyclic such as pentane, hexane, cyclohexane and heptane Hydrocarbons; halogenated hydrocarbons such as carbon tetrachloride, chloroform, and ethylene dichloride; nitro compounds such as nitromethane and nitrobenzene; ethers such as diethyl ether, methyl t-butyl ether, tetrahydrofuran, and 1,4-dioxane; methyl acetate; Esters such as ethyl acetate, isopropyl acetate and amyl acetate; alcohols such as dimethylformamide, methanol, ethanol and propanol; one or more ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone are used. It is possible.

The resin composition further includes, as necessary, inorganic fillers, low shrinkage agents (reactive oligomers or polymers, non-reactive oligomers or polymers), color pigments, plasticizers, chain transfer agents, and polymerization. Inhibitors, near infrared absorbers, light stabilizers, antioxidants, flame retardants, matting agents, dyes, antifoaming agents, leveling agents, antistatic agents, dispersants, slip agents, surface modifiers, shaking 1 type (s) or 2 or more types, such as a change agent and a thixotropic agent, can be used. The presence of these additives does not particularly affect the effects of the present invention.

What is necessary is just to set the compounding quantity of the said additive suitably according to the kind and use purpose of an additive, the use of a composition, a usage method, etc., and it is not specifically limited. For example, the blending amount of the inorganic filler is preferably 1 to 80 parts by weight, more preferably 10 to 60 parts by weight, and still more preferably 20 to 50 parts by weight with respect to 100 parts by weight of the total amount of the polymerizable components. The blending amount of the low shrinkage agent, the color pigment, the plasticizer or the auxiliary change agent is preferably 1 to 40 parts by weight, more preferably 5 to 30 parts by weight, still more preferably with respect to 100 parts by weight of the total amount of the polymerizable components. Is 10 to 25 parts by weight. The polymerization inhibitor, antioxidant, matting agent, dye, antifoaming agent, leveling agent, antistatic agent, dispersant, slip agent, surface modifier or auxiliary agent are blended in the above polymerizable components. Preferably it is 0.0001-10 weight part with respect to 100 weight part of total amounts, More preferably, it is 0.001-5 weight part, More preferably, it is 0.01-3 weight part.

[A more preferred form of the curable resin composition for optical recording media]
The curable resin composition of the present invention can be obtained by blending the above-described essential components and the above-mentioned components contained as necessary, and mixing and stirring by a usual method.
The viscosity of such a resin composition is appropriately set depending on a film forming method (for example, film formation by a spin coater), a desired thickness, and the like. Usually, when trying to uniformly obtain a coating film having a thickness of about 100 μm (for example, for a single-layer Blu-ray disc with a recording capacity of about 25 G) to a thickness of about 75 μm (for example, for a double-layer Blu-ray disc with a recording capacity of about 50 G) Is preferably at least 800 mPa · s at 25 ° C. and more preferably at most 2500 mPa · s. More preferably, it is 850 mPa * s or more, More preferably, it is 900 mPa * s, More preferably, it is 2300 mPa * s or less, More preferably, it is 2000 mPa * s or less, Most preferably, it is 1900 mPa * s or less. In addition, when it is desired to further reduce the thickness (for example, for a multilayer Blu-ray disc having three or more layers), it is preferable to further reduce the viscosity.
The viscosity of the resin composition can be calculated using a B-type viscometer (model “RB80L” manufactured by Toki Sangyo Co., Ltd.) under a temperature of 25 ° C.

The curable resin composition can be cured by irradiation with ultraviolet rays. The term “curing” as used herein means that there is no fluidity.
The wavelength of the ultraviolet rays used may be in the range of 150 to 450 nm. Examples of the light source that emits such a wavelength include sunlight, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, a gallium lamp, a xenon lamp, a flash type xenon lamp, and a carbon arc lamp. Irradiation integrated light quantity is preferably 0.1~3J / cm ^2, more preferably 0.2~2.0J / cm ^2, more preferably in the range of 0.3~1.0J / cm ^2.

The curable resin composition may be cured by heating together with curing by light irradiation. In this case, infrared light, far infrared light, hot air, high-frequency heating, or the like may be used together with the light source described above. The heating temperature may be appropriately adjusted according to the type of the substrate and the like, and is not particularly limited, but is preferably 80 to 200 ° C, more preferably 90 to 180 ° C, and still more preferably 100 to 170 ° C. Within range. The heating time may be appropriately adjusted according to the application area and the like, and is not particularly limited, but is preferably 1 minute to 24 hours, more preferably 10 minutes to 12 hours, and even more preferably 30 minutes to 6 hours. Is within the range.

The curable resin composition may be further cured by irradiation with an electron beam together with curing by light irradiation. In this case, the acceleration voltage is preferably 0 to 500 kV, more preferably 20 to 300 kV, and even more preferably 30 to 200 kV. The irradiation amount is preferably in the range of 2 to 500 kGy, more preferably 3 to 300 kGy, and still more preferably 4 to 200 kGy.

As for the curable resin composition of this invention, it is suitable for the hardened | cured material obtained by hardening | curing this curable resin composition that (A) glass transition temperature (Tg) will be 0-25 degreeC. . If the Tg is 25 ° C. or lower, the warpage of the cured product can be more sufficiently suppressed, and if it is 0 ° C. or higher, permanent deformation due to pressure marks or dents can be more sufficiently suppressed. The Tg is more preferably 5 ° C or higher, more preferably 20 ° C or lower, and further preferably 15 ° C or lower.

The curable resin composition may be such that a cured product obtained by curing the curable resin composition has a loss tangent tan δ at a glass transition temperature of 0.2 to 0.45. Is preferred. When the loss tangent tan δ is 0.45 or less, the long-term storage stability of the cured product becomes more sufficient, and permanent deformation due to pressure marks or dents can be further suppressed, and is 0.2 or more. And the curvature of hardened | cured material can be suppressed more fully, and it will be further excellent in long-term storage stability in any case. The loss tangent tan δ is more preferably 0.4 or less, still more preferably 0.35 or less, and still more preferably 0.3 or less.

A particularly preferable form of the curable resin composition is that a cured product obtained by curing the curable resin composition has (A) a glass transition temperature of 0 to 25 ° C. and (B) a glass transition temperature. Is a form in which the loss tangent tan δ is 0.2 to 0.45. As a result, in the cured product after curing, the three warpage properties (warpage resistance) are further improved, and the effect that the amount of permanent deformation due to press-contact marks, dents, and the like is further significantly reduced can be exhibited. It becomes possible to further exhibit the effect.

The curable resin composition is also preferably such that a cured product obtained by curing the curable resin composition has (C) a storage elastic modulus at 25 ° C. of 25 to 200 MPa. When the storage elastic modulus at 25 ° C. is 200 MPa or less, the warpage of the cured product is further reduced, and for example, the optical recording medium is further suitable when used in a cold region or stored for a long time. Moreover, it becomes possible to suppress more fully the permanent deformation by a press-contact mark, a dent, etc. as it is 25 Mpa or more. The storage elastic modulus at 25 ° C. is more preferably 40 MPa or more, more preferably 150 MPa or less, and further preferably 130 MPa or less.

The glass transition temperature, loss tangent tan δ and storage elastic modulus of the cured product were measured for dynamic viscoelasticity under the following measurement conditions for the cured product obtained by curing the curable resin composition by the following curing method. And use the value obtained. In addition, the glass transition temperature shall employ the temperature of the maximum tan δ value.
<Curing method>
A curable resin composition for an optical recording medium is applied on a polycarbonate substrate (PC substrate) having a thickness of 1.1 mm and a diameter of 120 mm with a spin coater at a thickness of 100 μm. The obtained PC substrate is irradiated with a flash of 15 times at a lamp height of 2 cm in a nitrogen atmosphere using a UV irradiator having a xenon flash UV lamp (model RC-801, manufactured by Xenon, USA) to complete the curing. . In addition, the irradiation integrated light quantity in 320-390 nm shall be about 0.5 J / cm < ² >.
<Measurement conditions>
The dynamic viscoelasticity is measured under the conditions of a tensile mode, a frequency of 1 Hz, a clamp distance of 25 mm, an amplitude of 0.1%, and a heating rate of 5 ° C./min.

[Cured product]
The present invention is also a cured product obtained by curing the curable resin composition for optical recording media. Such a cured product not only has excellent physical properties such as transparency, hardness, residual film properties, film thickness stability, film thickness uniformity, but also excellent surface smoothness, extremely small warpage, Permanent deformation (permanent deformation) due to dents or the like is sufficiently suppressed, and the long-term storage stability is remarkably excellent. Therefore, this cured product is particularly useful as a layer (cured film) constituting the optical recording medium.

It is preferable that the cured product has one or more of Tg, loss tangent tan δ at Tg, and storage elastic modulus within the above-mentioned range, and thereby a layer (cured) constituting an optical recording medium. Film).

It is also preferable that the cured product has a light transmittance of 850 nm or more at 405 nm with a thickness of 100 μm. When the light transmittance is 85% or more, the transparency becomes more sufficient, and it becomes possible to further prevent errors in reading recorded information. More preferably, it is 88% or more, More preferably, it is 89% or more.
The light transmittance can be measured with a spectrophotometer.

Further, the cured product preferably has a mass loss (mass reduction) rate of 0.1 to 2% by mass when held in an oven at 70 ° C. for 100 hours. The decrease in mass is considered to be caused by uncrosslinked polymerizable monomer components, residues of photopolymerization initiators and decomposition products thereof, low molecular weight additives, etc., but the mass decrease rate is 2% by mass or less. In addition, bleed-out of volatile components to the surface of the cured product and the occurrence of errors in reading recorded information due to changes in the thickness of the layer of the cured product can be further prevented, and the long-term storage stability of optical recording media can be improved. Furthermore, it can be made favorable. In addition, in order to make the said mass reduction rate less than 0.1 mass%, the drying (decompression) process etc. of hardened | cured material may be required. Therefore, by setting the mass reduction rate within the above range, for example, the surface accuracy of the optical recording medium is less decreased with time, and the storage stability is further improved. Is more possible. More preferably, it is 1.5 mass% or less, More preferably, it is 1 mass% or less.
The mass reduction rate is measured for a cured product having a thickness of 100 μm ± 2 μm.

[Optical recording medium]
The present invention is also an optical recording medium having a layer formed by curing the curable resin composition for an optical recording medium. Such an optical recording medium is an optical recording medium on which recording and / or reproduction is performed by blue laser light, and preferably has at least a substrate, a recording layer, a reflective film, and a protective layer. Each of these layers (including the substrate) may be composed of one layer or may be composed of multiple layers. Furthermore, it may have one or more other functional layers as necessary, and may have another functional layer between these layers. As other functional layers, for example, an intermediate layer formed between recording layers in a multilayer structure optical recording medium having two or more recording layers (information recording layers), and usually formed on a protective layer, Examples thereof include an antistatic layer, a water repellent layer, an oil repellent layer, and a hard coat layer. Also preferred is an interface layer formed between the recording layer and the protective layer. The optical recording medium of the present invention is particularly preferably a form having a hard coat layer.

The optical recording medium may be a single-layer optical recording medium having one recording layer, or a multilayer optical recording medium having two or three or more recording layers. That is, the curable resin composition for optical recording media of the present invention can be suitably used for either single-layer or multilayer optical recording media.

Since the curable resin composition is excellent in transparency and high in light transmission, it can be suitably used as a material for forming the light transmission layer of the optical recording medium. Among them, it is particularly preferably used for forming the protective layer, but it is also suitable to use as a material for forming the intermediate layer. That is, an optical recording medium having a protective layer and / or an intermediate layer obtained by curing the curable resin composition for an optical recording medium is one of the preferred embodiments of the present invention. In this case, low warpage (low shrinkage), transparency (light transmission), adhesion to the substrate (for example, polycarbonate substrate, etc.), low corrosion, recyclability, fast curability (productivity), antifouling Protective layer and intermediate layer satisfying all properties such as stability, dimensional stability, long-term storage stability (change in warpage during heating acceleration test, residual film property, small amount of permanent deformation such as pressure marks and dents) It becomes possible to do.
In the optical recording medium having a plurality of layers as a light transmission layer such as a protective layer or an intermediate layer, at least one of the light transmission layers is a layer obtained by curing the curable resin composition for an optical recording medium. Is preferred. Among these, at least one layer of the protective layer is more preferably a layer formed by curing the curable resin composition for optical recording media.

The said board | substrate is not specifically limited, For example, paper etc. can be utilized besides the resin substrate formed from a polycarbonate resin, a cycloolefin resin, a polyolefin resin, an acrylic resin, an epoxy resin etc. Usually, a resin substrate is adopted in consideration of strength, flexibility, etc. Among them, a substrate formed from a polycarbonate resin, that is, a polycarbonate substrate is preferable because of its high mechanical strength and low water absorption. is there. Moreover, since the linear expansion coefficient of the cured product is small in the polycarbonate resin, the synergistic effect of such a substrate and the layer obtained by curing the curable resin composition for optical recording media of the present invention makes the light more excellent in warping characteristics. A recording medium can be obtained. In addition, when the water absorption is low, a cured product having excellent dimensional stability can be provided, and water absorption into the cured product can be suppressed to a low level.
Although the thickness of the said board | substrate is not specifically limited, For example, it is suitable that it is 0.5-1.5 mm. More preferably, it is 0.7-1.2 mm, More preferably, it is 0.9-1.1 mm.

The recording layer is also called a recording part, and is a part for recording or reproducing information signals. As such a recording layer, a read-only optical recording medium may be integrated with a substrate. For example, a substrate having a pit shape is preferably employed. Specifically, it is preferable to form pits for recording information on the substrate on the surface laminated with the reflective film. In a recordable optical recording medium, the recording layer is preferably provided between the reflective film and the protective layer (light transmission layer).

The recording layer only needs to be capable of recording / reproducing information, and may be any of a phase change recording layer, a magneto-optical recording layer, and an organic dye recording layer. Among these, an organic dye type recording layer, that is, a layer using an organic dye is preferable. As the organic dye, it is preferable to use one or more organic compounds having an absorption band derived from the structure in the light wavelength region near 300 to 800 nm, for example. Specific examples of such organic dyes include methine, azo, metal-containing azo, pyrone, and porphyrin compounds.
The thickness of the recording layer is not particularly limited, but is preferably 1 to 100 nm, for example. More preferably, it is 1-50 nm, More preferably, it is 1-30 nm.

As described above, the intermediate layer is a layer formed between the recording layers in an optical recording medium having a multilayer structure having two or more recording layers (information recording layers), and is cured by active energy rays such as ultraviolet rays. It is suitable to form from the resin composition (ultraviolet curable resin composition) obtained. Preferably, as described above, the curable resin composition for optical recording media of the present invention is used.
Although the thickness of the said intermediate | middle layer is not specifically limited, For example, it is preferable that it is 1-50 micrometers. More preferably, it is 5-30 micrometers, More preferably, it is 8-28 micrometers.

The reflective film (also referred to as a reflective layer) is a film that reflects laser light for reading information. For example, a film made of gold, silver, aluminum, or an alloy containing these metals is suitable. Among these, silver or a silver alloy is preferable.
The thickness of the reflective film is preferably set as appropriate depending on the material constituting the reflective film, the layer structure, and the like. For example, in the case of a single layer, it is preferable to set the thickness so that the reflectance is 35 to 70% (L0). Usually, in the case of a silver alloy, the thickness is set to about 40 nm in order to make the reflectance about 45%. In addition, when the reflective layer (reflective film) has two layers, the reflective film (L1) located in the back as viewed from the laser light irradiation side is a film according to the material used so that the reflectance is 10 to 30%. It is preferable to set the thickness. Usually, in the case of a silver alloy, the thickness is set to about 20 nm in order to obtain a reflectance of about 20%. As the reflective layer of the present invention, when the layer is a layer using silver or a silver alloy, it is preferable to set the thickness to 10 to 50 nm. That is, at least one of the reflective layers is a layer using silver or a silver alloy, and the thickness of the layer is 10 to 50 nm is also a preferred embodiment of the present invention.

The thickness of the protective layer is preferably 20 to 150 μm. More preferably, it is 70-105 micrometers, More preferably, it is 70-102 micrometers, Most preferably, it is 70-100 micrometers. In the case of a more multilayer optical recording medium, it is preferable that the thickness of the protective layer is smaller and the thickness of the intermediate layer is larger.

As described above, the interface layer is preferably a layer formed between the recording layer and the protective layer. In particular, in the case of a recordable optical recording medium (also referred to as a recording / reproducing optical recording medium), the interface layer is further formed. It is preferable to have By providing this layer, the swelling of the recording layer to the protective layer can be used effectively. Further, for example, when a protective layer is formed by applying a resin composition containing a solvent, it is possible to prevent the recording layer from being eluted by recording with the solvent.

In the interface layer, it is preferable that the reflection at the interface layer is as small as possible in order to selectively use the phase change of the reflected light from the reflective film. Considering this point, it is preferable that the difference in refractive index between the interface layer and the recording layer or the difference in refractive index between the interface layer and the protective layer is small. Specifically, the difference is preferably 1 or less, more preferably 0.7 or less, and still more preferably 0.5 or less. Particularly preferably, both the difference in refractive index between the interface layer and the recording layer and the difference in refractive index between the interface layer and the protective layer are within these preferable ranges.

The interface layer is preferably made of a material that is transparent to the wavelength of the laser beam used and that is chemically, mechanically, and thermally stable. For example, it is preferable to use a material having a light transmittance of 405 nm of 80% or more. The light transmittance is more preferably 90% or more, and still more preferably 100%.

Specific examples of the material for forming the interface layer include dielectric compounds such as oxides such as metals and semiconductors, nitrides, carbides, sulfides, fluorides such as magnesium (Mg) and calcium (Ca), and mixtures thereof. Etc. are preferred. Among them, a material having a refractive index of 1 to 2.5 is preferable because the difference in refractive index between the recording layer and the protective layer is 1 or less. It is preferable to set the thickness of the interface layer as appropriate so that the refractive index of the layer also falls within this range. Depending on the hardness and thickness of the interface layer, the deformation of the recording layer (bulging deformation of the recording layer into the protective layer) can be promoted or suppressed. For example, in order to more effectively utilize the swelling toward the protective layer. Is preferably a dielectric material having a relatively low hardness, such as ZnO, In ₂ O ₃ , Ga ₂ O ₃ , ZnS, rare earth metal sulfides, oxides of other metals, semiconductors, nitrides The material which mixed the thing and the carbide | carbonized_material is suitable. A sputtered plastic film or a plasma polymerized film of hydrocarbon molecules can also be used.
The thickness of the interface layer is preferably 1 to 50 nm, for example. More preferably, it is 5-20 nm.

The hard coat layer is preferably provided in order to prevent dirt and small scratches on the optical recording medium. Such a hard coat layer is a layer having transparency, and is preferably a layer obtained by curing a resin composition that is cured by an active energy ray such as light.
The thickness of the hard coat layer is preferably 1 to 10 μm, for example. More preferably, it is 2-8 micrometers, More preferably, it is 3-5 micrometers.
The curable resin composition for optical recording media of the present invention also prevents the occurrence of cracks in the hard coat layer even when such a hard coat layer is provided on the cured film of the resin composition. It has the characteristic that

An optical recording medium having a layer obtained by curing the curable resin composition for an optical recording medium is obtained by, for example, forming the curable resin on a reflective film formed on a substrate (or a functional layer formed on the substrate). Although it can be obtained by forming a layer formed by curing the resin composition, the term “on the reflective film” as used herein refers not only to a form in which the layer is directly laminated on the reflective film, but also on the reflective film. It also means a form in which a functional layer is laminated and the layer is laminated on the functional layer.

As a method of forming a layer formed by curing the curable resin composition on the reflective film, a normal method may be employed. For example, a cured product of the resin composition is attached to the reflective film with an adhesive. Examples thereof include a method of combining them, and a method using a spin coater (spin coating method), but considering the cost, it is preferable to carry out by a spin coating method. The curable resin composition for an optical recording medium of the present invention is particularly suitable for film formation by a spin coating method, that is, specifically, the flowability is good and the direction from the center of the spin coater toward the outside. In this respect, it is preferable to employ the spin coating method because the film can be formed while sufficiently preventing the occurrence of unevenness.

Since the layer formed by curing the curable resin composition is formed from the curable resin composition of the present invention described above, the thickness change after curing can be controlled within ± 2 μm. The thickness of such a hardened layer can be appropriately set depending on the use of the hardened layer and the like. For example, when used as a material for forming the protective layer, the thickness of the protective layer can be set within a suitable range. preferable.

As described above, the optical recording medium of the present invention is preferably used as both a read-only optical recording medium and a recordable optical recording medium (also referred to as a recording / reproducing optical recording medium). For example, taking the case of a recording single layer type as an example, preferred forms and manufacturing methods of these types will be described below.

A form suitable as the read-only optical recording medium is a form having at least a resin substrate (preferably a polycarbonate substrate) having a pit shape, a reflective film, and a protective layer in this order. For example, when injection molding a single resin substrate, a pit as a recording layer is provided, a reflective film (also referred to as a reflective layer) is formed on the recording layer, and an ultraviolet ray is further formed on the reflective film. A method of forming a protective layer (light transmission layer) by applying a curable resin composition by a spin coat method or the like and then curing the composition by ultraviolet irradiation is exemplified. It is more preferable to further provide a hard coat layer on this protective layer.

A form suitable as the recording / reproducing optical recording medium is a form having at least a substrate (preferably a polycarbonate substrate), a reflective film, a recording layer, and a protective layer in this order. A reflective film is formed on a single substrate, and then a recording layer is provided. Further, an ultraviolet curable resin composition is applied on the recording layer by a spin coating method or the like, and then cured by ultraviolet irradiation to protect it. A method of forming a layer (light transmission layer) can be mentioned. It is more preferable to form a protective layer after providing the interface layer on the recording layer, and it is more preferable to further provide a hard coat layer on the protective layer.

Since the curable resin composition for an optical recording medium of the present invention has the above-described configuration, it can sufficiently exhibit various physical properties such as transparency and film thickness stability, and can be stably warped or permanent for a long time. Deformation is suppressed and a cured product having excellent surface smoothness can be provided. Use of such a curable resin composition is useful because an optical recording medium capable of recording and reproducing stably over a long period of several decades or more can be obtained with high efficiency and high productivity. An optical recording medium having a layer formed by curing such a curable resin composition is extremely reliable, and can be used in a cold district or a place where it is easily exposed to high temperatures such as in a car or for a long time. It is also suitable for storage.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.
In the following production examples, the number average molecular weight (Mn), molecular weight distribution (Mw / Mn), glass transition temperature, and storage elastic modulus of the polymer were measured by the methods described above. In addition, various physical properties in Examples and the like were evaluated by the following methods.

<Evaluation methods for various physical properties>
(1) Viscosity of Resin Composition The obtained resin composition (resin composition for forming a protective layer) is subjected to a B-type viscometer (model “RB80L”, manufactured by Toki Sangyo Co., Ltd.) at a temperature of 25 ° C. The measured value was used.
(2) Surface smoothness The obtained substrate / protective layer laminate (that is, in each example, the resin composition is set to a thickness of about 100 μm with a spin coater on a polycarbonate disc-shaped optical recording medium substrate) It is visually determined whether or not there is a poor smooth portion due to the flow mark of the resin composition on the polycarbonate disc-shaped optical recording medium substrate and protective layer obtained by applying and curing with did.
○: No flow mark of resin composition ×: Flow mark of resin composition

(3) Protective layer Storage modulus at 25 ° C. From the substrate / protective layer laminate obtained, only the protective layer (cured film (cured product) of the resin composition) is peeled off to a predetermined size, and the tensile mode and frequency The dynamic viscoelasticity was measured under the conditions of 1 Hz, a clamp distance of 25 mm, an amplitude of 0.1%, and a heating rate of 5 ° C./min, and the obtained storage elastic modulus value at 25 ° C. was adopted.
(4) Protective layer Glass transition temperature (Tg)
It is a value obtained by the same measurement method and conditions as the storage elastic modulus at 25 ° C. in (3) above, and the temperature of the maximum tan δ value was adopted.
(5) Protective layer Tan δ value at glass transition temperature The tan δ value of the glass transition temperature measured by the same measurement method and conditions as the storage elastic modulus at 25 ° C in (3) above was adopted.

(6) The amount of warpage at the time of curing (initial) The obtained laminate of substrate / protective layer / hard coat layer is horizontal so that the protective layer (cured film (cured product) of the resin composition) is on the upper surface side. After placing on a glass plate, a radial displacement value at a radius of 58 mm was measured using a laser displacement reading type warpage angle measuring device manufactured by Nippon Shokubai Co., Ltd. under an environment of a temperature of 25 ° C. and a relative humidity of 50%. The amount of warpage before and after coating was adopted as the amount of warpage during curing (initial).
(7) Increase in warpage at low temperature (5 ° C.) Increase in warpage when the obtained substrate / protective layer / hard coat layer laminate is left in an environment of 5 ° C. and 45% relative humidity for 5 hours. The value was measured in the same manner as the amount of warping at the time of curing (initial) in (6) above.
(8) Increase in warpage after heating acceleration test (70 ° C., 100 hours) The obtained substrate / protective layer / hard coat layer laminate was held in an oven at 70 ° C. for 100 hours, and further, temperature 25 ° C. The amount of increase in warpage when left in an environment of 50% relative humidity for 24 hours was measured in the same manner as the amount of warpage at the time of curing (initial) in (6) above.

(9) Warpage Comprehensive Evaluation Warpage amount during curing (initial), warpage increase at low temperature (5 ° C) and warpage after heating acceleration test (70 ° C, 100 hours) determined in (6) to (8) above. The amount of increase was summed and the obtained amount of warpage was evaluated according to the following criteria.
◎: Less than 0.5 ° ○: 0.5 ° or more, less than 0.7 ° △: 0.7 ° or more, less than 0.9 ° ×: 0.9 ° or more In addition, warp change of 0.9 ° or more If there is, there is a possibility that even if the manufacturing process is devised or the transparent cover resin is improved, it is difficult to improve the warpage.

(10) Pressure scar resistance Using a laminate of the obtained substrate / protective layer / hard coat layer, using a micro compression tester (manufactured by Shimadzu Corporation, model MCT-W500), as a test condition, a used flat indenter having a diameter of 50 μm, Deformation amount remaining in the laminate (permanent deformation amount) when the load speed is 20 mN / sec, the maximum load is 300 mN, the holding time at the maximum load is 90 seconds, the unloading speed is 20 mN / sec, and the holding time after complete unloading is 90 seconds. , Μm) and measured according to the following criteria.
A: The amount of permanent deformation is less than 0.5 μm: The amount of permanent deformation is 0.5 μm or more and less than 0.7 μm Δ: The amount of permanent deformation is 0.7 μm or more, less than 1.0 μm ×: The amount of permanent deformation is 1.0 μm or more

(11) Crack prevention property of HC (hard coat layer) Using the obtained substrate / protective layer / hard coat layer laminate, the same test as the pressure-resistant scar test of (10) above was carried out, and the hard coat layer The presence or absence of cracks was confirmed visually and evaluated according to the following criteria.
○: No crack ×: There is a crack

(12) Two fluorescent lamps of light resistance 36W (Panasonic FLR40S / W / MX / 36-S) are juxtaposed on the same plane so that the distance between the centers of the fluorescent lamps is 9 cm, and the central fluorescent lamp Was placed so that the laminate of the substrate / protective layer / hard coat layer (cured product layer on the fluorescent lamp side) faced at a position 8 cm from the side, and a light resistance test using a fluorescent lamp was performed. After 100 hours of exposure, the light transmittance at 405 nm of the cured product layer before and after that was measured using a spectrophotometer (model UV-3100, manufactured by Shimadzu Corporation) and evaluated according to the following criteria.
○: transmittance is 89% or more Δ: transmittance is 85% or more and less than 89% ×: transmittance is less than 85%

(13) Using a laser focus displacement meter, measure the thickness of the protective layer before and after the heating acceleration test (70 ° C., 100 hours) of (8) above for the laminate of residual film substrate / protective layer / hard coat layer. The remaining film ratio (%) was calculated by [(film thickness after the heating acceleration test / film thickness before the heating acceleration test) × 100] and evaluated according to the following criteria.
A: Remaining film ratio is 99% or more and less than 101% B: Remaining film ratio is 98% or more and less than 99%, or 101% or more and less than 102% X: Transmittance is less than 98% or 102% or more

Production Example 1 (Synthesis of UA-1)
340 g of isophorone diisocyanate and 0.015 g of dibutyltin dilaurate were added to a four-necked flask equipped with a stirring bar, a thermometer, a dropping line, and a nitrogen / air mixed gas introduction tube, and the temperature was raised to 80 ° C. After a certain temperature, 300 g of polypropylene glycol “P-2000” manufactured by Asahi Denka Co., Ltd. was dropped over 2 hours, and the temperature was maintained at 80 ° C. for 5 hours after the completion of dropping. Next, a mixture of 180 g of 2-hydroxyethyl acrylate and 0.5 g of hydroquinone monomethyl ether was added dropwise over 2 hours. After completion of dropping, a temperature of 80 ° C. was maintained for 15 hours, and urethane acrylate (referred to as “UA-1”) was synthesized. The molecular weight (Mn) was 5600, the molecular weight distribution (Mw / Mn) was 3.71, the glass transition temperature was −5 ° C., and the storage elastic modulus at 25 ° C. was 10 MPa.

Production Example 2 (Synthesis of UA-2)
300 g of polypropylene glycol “P-2000” manufactured by Asahi Denka Co., Ltd. in Production Example 1 was changed to a mixture of 150 g of polytetramethylene ether glycol “PTMG2000” manufactured by Mitsubishi Chemical Corporation and 150 g of polypropylene glycol “P-2000” manufactured by Asahi Denka Co. Except that, urethane acrylate (referred to as “UA-2”) was synthesized in the same manner as in Production Example 1 (UA-1). The molecular weight (Mn) was 5,500, the molecular weight distribution (Mw / Mn) was 3.61, the glass transition temperature was 10 ° C., and the storage elastic modulus at 25 ° C. was 150 MPa.

Production Example 3 (Synthesis of P-1)
150 g of ethyl acetate was added to a four-necked flask equipped with a stirring bar, a thermometer, a dropping line, and a nitrogen / air mixed gas introduction tube, and the temperature was raised to 70 ° C. After heating, a mixture of 15 g of 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA, Nippon Shokubai Co., Ltd.) and 185 g of 2-ethylhexyl vinyl ether, and a mixed solution of 25 g of ethyl acetate and 13 mg of phosphotungstic acid, The polymerization was carried out by dropping each over 3 hours. After completion of the polymerization, the reaction was terminated by adding triethylamine. Subsequently, after concentrating with an evaporator, a vinyl polymer (referred to as “P-1”) was obtained. The reaction rate of the monomer is 99.5% by analyzing the mixed solution after stopping the reaction by gas chromatography (GC), and the content of ethyl acetate is 0.1%. There was found. The number average molecular weight (Mn) of the obtained vinyl polymer (P-1) is 2200, the molecular weight distribution (Mw / Mn) is 1.50, the glass transition temperature is −5 ° C., and the elastic modulus at 25 ° C. is 30 MPa.

Production Example 4 (Synthesis of P-2)
A mixture of 15 g of 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA, manufactured by Nippon Shokubai Co., Ltd.) and 185 g of 2-ethylhexyl vinyl ether was mixed with 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA, manufactured by Nippon Shokubai Co., Ltd.). ) A vinyl polymer (referred to as “P-2”) was obtained in the same manner as in Production Example 3 (P-1) except that the mixture was changed to a mixture of 40 g and 160 g of 2-ethylhexyl vinyl ether. The reaction rate of the monomer is 99.6% by analyzing the mixed solution after the reaction is stopped by gas chromatography (GC), and the content of ethyl acetate is 0.1%. There was found. The number average molecular weight (Mn) of the obtained vinyl polymer (P-2) is 2400, the molecular weight distribution (Mw / Mn) is 1.55, the glass transition temperature is 15 ° C., and the elastic modulus at 25 ° C. is 150 MPa. Met.

Example 1
(Preparation of protective layer)
25 parts of urethane acrylate UA-1 synthesized in Production Example 1, 25 parts of triacrylate of trimethylolpropane ethylene oxide 3 mol adduct (trade name “light acrylate TMP-3EO-A”, manufactured by Kyoeisha Chemical Co., Ltd.), bisphenol A 40 parts of diacrylate of ethylene oxide 10 mol adduct (trade name “SR-602”, manufactured by Sartomer), diacrylate of propylene oxide 2 mol adduct of neopentyl glycol (trade name “SR-9003”, manufactured by Sartomer) ) 10 parts and 2 parts of 1-hydroxy-cyclohexyl-phenyl-ketone (trade name “Irgacure 184”, manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator are mixed and stirred for an optical recording medium. A curable resin composition (1) was prepared.

(Preparation of hard coat layer)
30 parts of dipentaerythritol hexaacrylate, 30 parts of trimethylolpropane triacrylate, 40 parts of 2- (2-hydroxyethoxy) ethyl acrylate, 1-hydroxy-cyclohexyl-phenyl-ketone (trade name “Irgacure 184” as a photopolymerization initiator ”, 5 parts of Ciba Specialty Chemicals Co., Ltd.), 0.3 part of silicone additive (trade name“ FZ-2104 ”manufactured by Toray Dow Corning Co., Ltd.), and mixed and stirred to hard coat for optical recording medium A resin composition was prepared.

(Formation of protective layer 1)
Next, a polycarbonate disk-shaped optical recording medium substrate having a thickness of 1.1 mm and a diameter of 120 mm was prepared (a warp angle of 0.0 °), and a silver alloy was sputtered thereon to a thickness of 20 to 40 nm. . Next, the obtained curable resin composition (1) for an optical recording medium was applied on a silver alloy with a spin coater at an ambient temperature of 25 ° C. and a relative humidity of 50%. Using a UV irradiator having a flash UV lamp (model RC-801, manufactured by Xenon, USA), the flash was irradiated 15 times at a lamp height of 2 cm in a nitrogen atmosphere and cured. In addition, the irradiation integrated light quantity in 320-390 nm was about 0.5 J / cm < ² >. When the thickness of the cured product (protective) layer was measured using a laser focus displacement meter, it was 97 ± 2 μm.

(Formation of hard coat layer)
Next, the obtained curable resin composition for hard coat for optical recording media was applied on a cured product (protective) layer with a spin coater at a thickness of about 3 μm, and a UV having a xenon flash UV lamp. Using an irradiator (model RC-801, manufactured by Xenon, USA), a flash was irradiated 10 times at a lamp height of 2 cm in a nitrogen atmosphere and cured. It was 100 +/- 2micrometer when the thickness of the laminated body (protective layer / hard-coat layer) of the obtained hardened | cured material layer was measured using the laser focus displacement meter.
The obtained curable resin composition for optical recording media (1) and the obtained optical recording medium (substrate / protective layer / hard coat layer laminate (*)) were evaluated. The results are shown in Table 1.
* Except for the 3 warp increase, warp comprehensive evaluation, pressure scar resistance, HC crack prevention property, residual film property and light resistance evaluation test, the hard coat layer is not laminated, that is, the substrate / protective layer laminate Was evaluated and measured.

Example 1-2
After the sputtering process of the silver alloy in (Formation 1 of protective layer) of Example 1, the curable resin composition (1) was cured by the following method to form a cured product (protective) layer, and then Example Various evaluations of the optical recording medium (substrate / protective layer / hard coat layer laminate or substrate / protective layer laminate) were performed in the same manner as in Example 1. The results were almost the same. In this case, the hard coat layer was formed in the same manner as in Example 1.
(Formation of protective layer 2)
After the sputtering process (film thickness of 20 to 40 nm) of the silver alloy in (Formation 1 of protective layer) of Example 1, a metal-containing azo dye was used as an organic dye-based recording layer with a thickness of 10 to 20 nm using a spin coater. A film was formed. Next, ITO (indium tin oxide) was sputtered on the metal-containing azo dye as an interface layer to a thickness of 5 to 10 nm. Next, the obtained curable resin composition (1) was applied on the ITO film with a spin coater at a thickness of about 100 μm under an environment of an ambient temperature of 25 ° C. and a relative humidity of 50%, and a xenon flash UV lamp was applied. Using a UV irradiation machine (model RC-801, manufactured by Xenon, USA), a flash was irradiated 15 times at a lamp height of 2 cm in a nitrogen atmosphere and cured. In addition, the irradiation integrated light quantity in 320-390 nm was about 0.5 J / cm < ² >. When the thickness of the cured product (protective) layer was measured using a laser focus displacement meter, it was 97 ± 2 μm.

Examples 2 to 19, Comparative Examples 1 to 8, Reference Example 1
In the same manner as in Example 1 (Preparation of protective layer), each component was mixed and stirred at the ratios shown in Tables 1 to 3, and curable resin compositions for optical recording media (2) to (19) were compared. Resin compositions (1) to (8) and a reference resin composition (1) were obtained. Then, it replaced with the curable resin composition (1) for optical recording media in Example 1, and obtained the optical recording medium like Example 1 except having used each of these resin compositions. The obtained resin composition and optical recording medium were evaluated in the same manner as in Example 1. The results are shown in Tables 1-3.

Abbreviations in Tables 1 to 3 are as follows. In addition, Tg and storage elastic modulus of (c) component in Tables 1-3 mean Tg and storage elastic modulus (25 degreeC) of the hardened | cured material which hardened it, respectively. Moreover, as molecular weight (* 1) in Tables 1-3, in (a), (b) and (d) component, it means a value calculated as the sum of atomic weights of constituent elements, and in (c) component It means number average molecular weight (Mn).
TMP-3EO-A: triacrylate of trimethylolpropane ethylene oxide 3 mol adduct (trade name “TMP-3EO-A”, manufactured by Kyoeisha Chemical Co., Ltd.)
TMP-6PO-A: Triacrylate of propylene oxide 6 mol adduct of trimethylolpropane (trade name “CD501”, manufactured by Sartomer)
TMP-9EO-A: Triacrylate of trimethylolpropane adduct with 9 moles of ethylene oxide (trade name “SR502”, manufactured by Sartomer)
G-PO-A: Triacrylate of propylene oxide 5.5 mol adduct of glycerin (trade name “CD9021”, manufactured by Sartomer)
PET-4EO-A: Tetraacrylate of ethylene oxide 4 mol adduct of pentaerythritol (trade name “SR494”, manufactured by Sartomer)
DPCA-120: hexaacrylate of dipentaerythritol ε-caprolactone 12 mol adduct (trade name “Kayarad DPCA-120”, manufactured by Nippon Kayaku Co., Ltd.)
DPCA-60: hexaacrylate of 6-mol adduct of ε-caprolactone of dipentaerythritol (trade name “Kayarad DPCA-60”, manufactured by Nippon Kayaku Co., Ltd.)

Bis10EO-A: Diacrylate of ethylene oxide 10 mol adduct of bisphenol A (trade name “SR-602”, manufactured by Sartomer)
APG-700: diacrylate of polypropylene glycol (trade name “NK Ester APG-700”, manufactured by Shin-Nakamura Chemical Co., Ltd.)
HX-620: Diacrylate of ε-caprolactone 4 mol adduct of hydroxypivalic acid neopen glycol (trade name “Kayarad HX-620”, manufactured by Nippon Kayaku Co., Ltd.)
NP-2PO-A: diacrylate of propylene oxide adduct of neopentyl glycol (trade name “SR9003”, manufactured by Sartomer)

UA-1: urethane acrylate obtained in Production Example 1 UA-2: urethane acrylate obtained in Production Example 2 CN978: urethane acrylate manufactured by Sartomer
CN9178: manufactured by Sartomer, urethane acrylate CN2270: manufactured by Sartomer, polyester acrylate P-1: vinyl polymer obtained in Production Example 3 P-2: vinyl polymer obtained in Production Example 4 CN UVE151: manufactured by Sartomer , Epoxy acrylate CN981: made by Sartomer, urethane acrylate

TMPTA: Trimethylolpropane triacrylate (trade name “SR351”, manufactured by Sartomer)
TCD-A: Tricyclodecane diacrylate (trade name “Light Acrylate DCP-A”, manufactured by Kyoeisha Chemical Co., Ltd.)
PEA: Phenoxyethyl acrylate (trade name “Light Acrylate PO-A”, manufactured by Kyoeisha Chemical Co., Ltd.)
VEEA: 2- (2-vinyloxyethoxy) ethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.)

Irg184: 1-hydroxy-cyclohexyl-phenyl-ketone (trade name “Irgacure 184”, manufactured by Ciba Specialty Chemicals)
Irg127: 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propane (trade name “Irgacure 127”, Ciba Specialty Chemicals (Made by company)
Esacure one: oligo {2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone} (trade name “Escure ONE”, manufactured by Lamberti)

From the results of the above-mentioned Examples and Comparative Examples, the curable resin composition for optical recording media of the present invention was subjected to (a) trifunctional or higher functional (meth) acrylate compound 20 modified with alkylene oxide and / or ε-caprolactone. ˜75% by mass, (b) 1 to 55% by mass of a bifunctional (meth) acrylate compound modified with alkylene oxide and / or ε-caprolactone, and (c) 2 radically polymerizable unsaturated groups in the molecule. At least one selected from the group consisting of urethane (meth) acrylate compounds, polyester (meth) acrylate compounds, epoxy (meth) acrylate compounds, and oligomers or polymers having a (meth) acryloyl group in the side chain. 20 to 60% by mass of the compound, and (d) (meth) acrylates other than the components (a), (b) and (c) (However, each numerical range is the content ratio (mass of each component when the total amount of (a), (b), (c) and (d) is 100% by mass). %))), And (e) a cured product obtained by including a photopolymerization initiator has a surface smoothness, various warping properties, scratch resistance, weather resistance, and remaining film properties. In addition, it has an advantageous effect in that various properties can be exhibited simultaneously in a balanced manner, that is, it is possible to prevent the occurrence of cracks when the hard coat layer is laminated (HC crack prevention property), which is remarkable. It was confirmed. This will be described below.

That is, all of the resin compositions of Examples 1 to 19 are resin compositions of the above form, but the surface smoothness, various warping characteristics, pressure scar resistance, HC crack prevention properties, light resistance and residual film properties. It can be seen that both give good cured products.

In contrast, Comparative Examples 2 and 7 are examples in which the content ratio of the component (c) is less than the lower limit of the numerical range of the present invention, and in Comparative Example 2, the content ratio of the component (a) is the present invention. This is an example that exceeds the upper limit of the numerical range. In this case, in both Comparative Examples 2 and 7, the pressure scar resistance is not sufficient, and in Comparative Example 2, the warpage resistance is not sufficient. In Comparative Example 7, the surface smoothness and the HC crack prevention properties are inferior. Further, Comparative Example 4 is an example in which the content ratio of the component (c) exceeds the upper limit value of the numerical range of the present invention. In this case as well, the surface smoothness and the HC crack prevention properties are poor.

Comparative Example 1 is an example in which the content ratio of the component (d) exceeds the upper limit of the numerical range of the present invention, but in this case, the HC crack prevention property, light resistance, and remaining film property are inferior. Comparative Example 3 is an example in which the content ratio of the component (a) is less than the lower limit value of the numerical range of the present invention, and the content ratio of the component (b) exceeds the upper limit value of the numerical range of the present invention. Also in this case, the HC crack prevention property and the remaining film property are inferior. Further, Comparative Example 5 does not include the component (a), and Comparative Example 6 does not include the component (b). In these cases, the warping resistance and the pressure scar resistance are not sufficient. .

In addition, from the results of Examples and Reference Example 1, as a component (c), a single cured product containing a compound having a storage elastic modulus at 25 ° C. of 1 to 300 MPa enables various warpages and permanent deformation amounts. It turns out that it can suppress more fully.

Claims (5)

A curable resin composition used for an optical recording medium for recording and / or reproducing with blue laser light,
The curable resin composition is
(A) 20 to 75% by mass of a trifunctional or higher functional (meth) acrylate compound modified with alkylene oxide and / or ε-caprolactone;
(B) 1 to 55% by mass of a bifunctional (meth) acrylate compound modified with alkylene oxide and / or ε-caprolactone,
(C) Urethane (meth) acrylate compound, polyester (meth) acrylate compound, epoxy (meth) acrylate compound having 2 or more radically polymerizable unsaturated groups in the molecule, and (meth) acryloyl group in the side chain 20 to 60% by weight of at least one compound selected from the group consisting of oligomers or polymers;
(D) (0) to 20% by mass of (meth) acrylate compound other than the components (a), (b) and (c) (however, each numerical range is (a), (b), (c) And the content ratio (% by mass) of each component when the total amount of (d) is 100% by mass).
Further, (e) a curable resin composition for optical recording media, comprising a photopolymerization initiator. The curable resin composition for optical recording media according to claim 1, wherein the component (c) includes a compound having a storage elastic modulus at 25 ° C. of a single cured product of 1 to 300 MPa. The curable resin composition is a cured product obtained by curing the curable resin composition.
(A) The glass transition temperature is 0 to 25 ° C., and
(B) The loss tangent tan δ at the glass transition temperature is 0.2 to 0.45, and the curable resin composition for an optical recording medium according to claim 1 or 2. Hardened | cured material obtained by hardening | curing the curable resin composition for optical recording media in any one of Claims 1-3. An optical recording medium comprising a layer formed by curing the curable resin composition for an optical recording medium according to claim 1.