JP2010238322A - Curable resin composition for optical disk, cured material thereof and optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable resin composition for an optical disk which can give a cured material in which permanent deformation of pressure welding marks, dents, or the like is sufficiently suppressed and achieve more reliable recording and reproducing, wherein warpage is remarkably small, and to provide a cured material obtained by curing the same, and an optical disk having a layer formed by curing such a resin composition. <P>SOLUTION: The curable resin composition for the optical disk includes (a) a (meta) acrylate compound having an alicyclic structure and/or an aliphatic heterocyclic structure, (b) at least one species of a compound selected from a group consisting of a urethane (meta) acrylate compound, a polyester (meta) acrylate compound, an epoxy (meta) acrylate compound, and oligomer and/or polymer having a (meta) acryloyl group at a side chain, (c) another (meta) acrylate compound, and further (d) a photopolymerization initiator. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a curable resin composition for optical discs, a cured product thereof, and an optical disc. More specifically, the present invention relates to a curable resin composition used for an optical disc such as a Blu-ray disc, a cured product thereof, and an optical disc using the resin composition.

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, Blu-ray discs that record and reproduce information with blue laser light have been developed and sold.

In this new standard, blue laser light with a wavelength of 405 nm is used to increase the capacity of optical recording media, and the numerical aperture (NA) of the recording / reproducing optical system objective lens (optical lens) is increased to 0.85. The laser beam spot diameter during recording / playback is reduced to about 0.44 times that of DVD, and the track pitch (interval) at which signals are recorded is reduced to about 0.43 times, so that it is more than about 5 times that of DVD. Large capacity has been realized.

In general, a transparent protective layer (cover layer) is applied to the optical disk as a protection from scratches and dust on the optical disk surface as viewed from the laser incident side. The thickness of the protective layer (height of the protective layer; the distance between the disc surface and the signal recording surface) was about 600 μm for DVDs, but about 100 μm for Blu-ray discs to achieve high NA. As a result, the laser beam spot distortion (blurring) caused by tilting of the disk due to the warpage of the disk is suppressed, and highly reliable recording / reproduction is realized.

Regarding such a protective layer of an optical disk, Patent Document 1 describes that a very high uniformity is required because the uniformity of the thickness has a great influence on the recording and reproduction of information. Document 2 describes the necessity for the thickness unevenness from the disk surface to the recording layer to clear a tolerance of ± 2 μm. Further, in Patent Document 3, when a laminated sheet is used as a protective layer, the spot position of the laser beam fluctuates due to a scratch such as a compression mark or a dent generated when the laminated sheet is wound, and data writing or reading is performed. It is described that an error occurs.

As for a resin composition used for a protective layer of an optical disk, for example, Patent Document 4 discloses a light transmission layer including at least one resin layer and having a tensile yield strength and a tensile yield elongation in a specific range. Specifically, an ultraviolet curable resin containing a bifunctional oligomer, a monofunctional acrylic monomer, and a photopolymerization initiator is disclosed as a resin to be used. Patent Document 5 discloses an optical recording medium having a warp suppression layer, a support base, a reflective film, a second dielectric layer, a recording layer, a first dielectric layer, and a light transmission layer in this order. An acrylic resin or an epoxy resin is disclosed as a resin for forming the transmission layer. Patent Document 6 discloses a light-transmitting layer in which the product of the elastic modulus at 30 ° C. and the film thickness is in a specific range. Specifically, bisphenol A type epoxy (meth) acrylate and urethane (meth) acrylate are used. In addition, an ultraviolet curable composition containing another (meth) acrylate compound and a photopolymerization initiator is disclosed. Patent Document 7 discloses a curable composition containing urethane (meth) acrylate, two types of (meth) acrylate having a specific structure, a photopolymerization initiator and an amino ether light stabilizer as a composition for forming a light transmission layer. Things are disclosed. Patent Document 8 discloses a composition containing a urethane (meth) acrylate compound, another ethylenically unsaturated compound and a photopolymerization initiator as a composition for forming a protective layer.

JP 2006-351102 A (page 3 etc.) JP 2007-115356 A (pages 2 to 3 etc.) JP 2008-126518 A (pages 1 and 2 etc.) JP 2002-157782 A (2nd, 8th pages, etc.) JP 2003-132596 A (3rd page, FIG. 1 etc.) JP 2007-102980 (No. 2, 8, 11-14 pages, etc.) JP 2007-213744 A (2nd page etc.) Japanese Patent Laying-Open No. 2005-158253 (second page, etc.)

As described above, various resin compositions for optical disks have been developed.
Here, if the thickness of the protective layer constituting the optical disk is uneven, it affects information recording / reproduction. Therefore, the thickness of the protective layer is required to be uniform, and the thickness is within 100 μm ± 2 to 3 μm. However, from the viewpoint of stable information recording / reproduction for a long period of time, it is also required that the change in the thickness of the protective layer is small during disk storage. Also, if there are scratches (permanent deformation) such as compression marks or dents on the disc, the laser spot position will fluctuate, and this may also affect the recording / reproducing of information. It is desirable to sufficiently prevent this.

In addition, as a method for forming the protective layer, mainly a sheet bonding method in which a polycarbonate sheet is bonded with an ultraviolet curable adhesive, 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, but at present, the spin coating method is mainly used from the viewpoint of cost. However, in the case where the protective layer is formed using an ultraviolet curable resin, in addition to being required to have a uniform film thickness, the optical disk is often warped mainly by curing shrinkage of the ultraviolet curable resin. is there. For this reason, the disk substrate is warped in advance opposite to the coated surface, or correction or the like is performed by a reproducing / recording device. However, if warpage exceeding an allowable range (correctable range) occurs, the optical disk is In some cases, accurate data recording and reproduction cannot be performed, and it is not possible to insert / remove to / from the reproduction / recording apparatus.

Therefore, the resin composition constituting the protective layer of the optical disk has sufficient permanent deformation in addition to the properties of high hardness and excellent transparency and film thickness uniformity when cured. In addition, it is desired to sufficiently exhibit the characteristics that the warpage is extremely small, but no conventional resin composition has yet been able to achieve both of these characteristics sufficiently.

In view of the above-mentioned present situation, the present invention can provide a cured product in which warpage is remarkably small and permanent deformation such as pressure marks and dents is sufficiently suppressed, and more reliable recording and reproduction can be realized. An object of the present invention is to provide a curable resin composition for an optical disc, a cured product obtained by curing the same, and an optical disc having a layer obtained by curing such a resin composition.

The present inventors have made various studies on curable resin compositions used for large-capacity optical discs such as Blu-ray discs, and (a) an alicyclic structure in which a cured product of a homopolymer exhibits a specific glass transition temperature (Tg) and (Or) a (meth) acrylate compound having an aliphatic heterocyclic structure, (b) a (meth) acrylate compound having a specific structure and a single cured product exhibiting a specific Tg value and elastic modulus, c) When the resin composition contains other (meth) acrylate compound in a specific content ratio and further contains (d) a photopolymerization initiator, the cured product has transparency, hardness and remaining film properties. Not only is it excellent, but it is found that the warpage is remarkably small and permanent deformation (permanent deformation) due to pressure marks or dents is sufficiently suppressed, and a cured product with extremely excellent long-term storage stability can be obtained. It was found. Further, the inventors have found that such a curable resin composition is particularly useful for a protective layer in a high-capacity optical disc such as a Blu-ray disc, and conceived that the above problems can be solved brilliantly. Has reached
In the present invention, the small warpage means not only that the initial warpage is small, but also that the warpage does not increase (small) during the heat resistance test (heating acceleration test) for confirming long-term stability, “Excellent long-term storage stability” means that the amount of permanent deformation such as low warpage, residual film property, pressure marks and dents at the initial stage or during the heating acceleration test is small.

That is, the present invention is a curable resin composition used for an optical disc having a substrate, a reflective film that reflects a laser beam for reading information, and a protective layer having a thickness of 20 to 150 μm in this order. The resin composition comprises (a) a (meth) acrylate compound having an alicyclic structure and / or an aliphatic heterocyclic structure, wherein the glass transition temperature of the homopolymer cured product is 50 ° C. or higher, and (b) urethane (meta ) At least one compound selected from the group consisting of an acrylate compound, a polyester (meth) acrylate compound, an epoxy (meth) acrylate compound, and an oligomer or polymer having a (meth) acryloyl group in the side chain, It has two or more radically polymerizable unsaturated groups in it, the glass transition temperature of a single cured product is 15 to 100 ° C., and 2 A compound having an elastic modulus at 150 ° C. of 150 to 2000 MPa (excluding a compound corresponding to the component (a)), and (c) a (meth) acrylate compound other than the components (a) and (b), (A) 20 to 55% by mass, (b) 15 to 65% by mass, and (c) 5 to 40% by mass with respect to the total amount of these (a), (b) and (c) components of 100% by mass. The curable resin composition is a curable resin composition for optical discs further containing (d) a photopolymerization initiator.
The present invention is also a cured product obtained by curing the above curable resin composition for optical disks.
The present invention is also an optical disc having a layer formed by curing the curable resin composition for an optical disc.
The present invention is described in detail below.

The curable resin composition for an optical disk of the present invention is used for an optical disk having a substrate, a reflective film that reflects a laser beam for reading information, and a protective layer having a thickness of 20 to 150 μm in this order. As long as it is an optical disc in which a reflective film and a protective layer are essential, it may have other functional layers, and may have other functional layers between these layers.

The curable resin composition for optical disks (hereinafter, also simply referred to as “resin composition”) has an alicyclic structure and / or an aliphatic structure in which the glass transition temperature of (a) a homopolymer cured product is 50 ° C. or higher. (Meth) acrylate compound having a heterocyclic structure and (b) urethane (meth) acrylate compound, polyester (meth) acrylate compound, epoxy (meth) acrylate compound, and oligomer having (meth) acryloyl group in the side chain or At least one compound selected from the group consisting of polymers, having two or more radically polymerizable unsaturated groups in the molecule, the glass transition temperature of a single cured product being 15 to 100 ° C., and 25 A compound having an elastic modulus at 150 ° C. of 150 to 2000 MPa (excluding a compound corresponding to (a)), (c) the (a) and ( ) And other (meth) acrylate compounds, those containing a (d) a photopolymerization initiator. Each of these essential 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, the (meth) acrylate compound (a) is referred to as “(meth) acrylate compound (a)” or “(a) component”, and the compound (b) is referred to as “compound (b)” or “(b)”. The “component” and the (meth) acrylate compound (c) above are also referred to as “(meth) acrylate compound (c)” or “component (c)”.

In the curable resin composition for optical discs, the content ratios of the components (a), (b), and (c) are (a) 20 to 55% by mass with respect to the total amount of 100% by mass, ( b) 15 to 65% by mass and (c) 5 to 40% by mass are appropriate. By setting in such a range, in addition to the properties that the hardness of the cured product is high and excellent in transparency, residual film properties, and film thickness uniformity, permanent deformation is sufficiently suppressed and warpage is suppressed. However, if the content ratio of each component is out of the above range, such an effect cannot be exhibited. For example, if the content ratio of the component (a) is less than the above range, permanent deformation cannot be sufficiently suppressed, and if the content ratio of the component (c) is less than the above range, warping after curing can be sufficiently suppressed. Therefore, there is a possibility that a cured product having excellent long-term storage stability cannot be obtained.
The preferable range of the content of the component (a) is 30 to 55% by mass, and more preferably 30 to 40% by mass with respect to 100% by mass of the total amount of the components (a), (b) and (c). Moreover, the preferable range of the content rate of (b) component is 20-60 mass%, More preferably, it is 30-50 mass%, The preferable range of the content rate of (c) component is 5-30 mass%, More preferably It is 10-30 mass%, More preferably, it is 10-20 mass%.

The (meth) acrylate compound (a) has an alicyclic structure and / or an aliphatic heterocyclic structure in the molecule, and the alicyclic structure is an alicyclic structure having 3 to 30 carbon atoms. Is preferred. More preferably, it has 6 to 20 carbon atoms. Moreover, as an aliphatic heterocyclic structure, it is suitable that a hetero atom is an oxygen atom, and it is preferable that the number of members of a heterocyclic ring is 4-30, More preferably, it is 6-20.
The (meth) acrylate compound (a) is preferably in the form of a monomer (monomer).

The (meth) acrylate compound (a) is also suitably a compound having a glass transition temperature of 50 ° C. or higher of the homopolymer cured product. Thereby, a hardened | cured material can be obtained and it becomes possible to fully suppress the amount of permanent deformation in hardened | cured material. More preferably, it is 60 degreeC or more, More preferably, it is 70 degreeC or more. Further, from the viewpoint of sufficiently preventing warpage, 300 ° C. or lower is suitable, more preferably 280 ° C. or lower, and further preferably 250 ° C. or lower.
The glass transition temperature is a value obtained by a dynamic viscoelasticity measurement method under the following measurement conditions for a cured product obtained by curing a homopolymer, and the temperature of the maximum tan δ value is adopted.
<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.

Specific examples of the (meth) acrylate compound (a) include, for example, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, glycidyl (meth) acrylate, and dicyclopentenyl (meth) acrylate. , Monofunctional (monofunctional) (meth) acrylate compounds having an alicyclic structure such as dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate; dimethylol-tricyclodecane di (meth) acrylate, penta Cyclopentadecane dimethanol di (meth) acrylate, cyclohexane dimethanol 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-menthane-3,8-diol di (meth) acrylate, bicyclo [2.2.2] -octane-1-methyl-4-isopropyl-5,6-dimethylol di Polyfunctional (meth) acrylate compounds having an alicyclic structure such as (meth) acrylate; dioxolane diacrylate, 4- (meth) acryloyloxymethyl-2-methyl-2-ethyl-1,3-dioxolane, 4- (meta ) Acryloyloxymethyl-2-methyl-2-isobutyl-1,3-dioxolane, 4- (meth) acryloyloxymethyl-2-cyclohexyl-1,3-dioxolane, 4- (meth) acryloyloxymethyl-2,2 -Dioxolane-based (meth) acrylate compounds such as dimethyl-1,3-dioxolane Dioxane-based (meth) acrylate compounds such as compounds represented by the following formula (3) (2- (meth) acryloyloxyisobutyl-5-ethyl-5- (meth) acryloyloxymethyl-1,3-dioxane), etc. One type or two or more types are preferable.

Among the (meth) acrylate compounds (a), it is preferable to use a monofunctional compound and a polyfunctional compound in combination. Thereby, permanent deformation is further sufficiently prevented, and a cured product that is more excellent in long-term storage stability can be provided. Thus, the (meth) acrylate compound (a) comprises (a1) a monofunctional (meth) acrylate compound having an alicyclic structure and / or an aliphatic heterocyclic structure, and (a2) an alicyclic structure and / or a fat. A form that is a mixture with a polyfunctional (meth) acrylate compound having a heterocyclic group structure is also a preferred form of the present invention. In addition, these (a1) and (a2) can use 1 type (s) or 2 or more types, respectively.

As said monofunctional (meth) acrylate compound (a1), what is necessary is just a compound which has an alicyclic structure and / or an aliphatic heterocyclic structure, and has one (meth) acrylic acid ester site | part in a molecule | numerator, Moreover, as a polyfunctional (meth) acrylate compound (a2), if it is a compound which has an alicyclic structure and / or an aliphatic heterocyclic structure, and has two or more (meth) acrylic acid ester site | parts in a molecule | numerator. Good. Examples of these compounds include monofunctional or polyfunctional (meth) acrylate compounds having the alicyclic structure described above, and monofunctional or polyfunctional (meth) acrylate compounds having an aliphatic heterocyclic structure such as dioxane or dioxalane. Is preferably used.

When the said (meth) acrylate compound (a) is a mixture of a monofunctional (meth) acrylate compound (a1) and a polyfunctional (meth) acrylate compound (a2), these content rates are (a1) and (a2). ) Is a mixture of (a), (b), and (c), and the total amount is 100% by mass, (a1) is 10 to 30% by mass, and (a2) is 10 to 25%, respectively. It is suitable that it is mass%. By setting in such a range, in addition to the property that the hardness of the cured product is high, and excellent in transparency and film thickness uniformity, the permanent deformation is sufficiently suppressed and the warpage is remarkably small. The excellent characteristics can be fully exhibited. More preferably, (a1) is 15 to 30% by mass and (a2) is 15 to 25% by mass with respect to 100% by mass of the total amount of the components (a), (b) and (c).

The compound (b) is 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. It is at least one compound, a compound having two or more radically polymerizable unsaturated groups in one molecule, and a compound not corresponding to the (meth) acrylate compound (a).
Such a compound (b) may be in the form of a monomer, oligomer or polymer, but is preferably an oligomer or polymer.

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.
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 -1,5-pentanediol, polyethylene glycol, polypropylene glycol, 1,4-dimethylolbenzene, glycerin, trimethylolpropane, pentaerythritol, polytetramethylene glycol, polyester polyol, polycaprolactone polyol, and the like.
Examples of the organic polyisocyanate include tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and the like.
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 limited as long as it is an oligomer or polymer having a (meth) acryloyl group in the side chain and having two or more polymerizable unsaturated groups in the molecule. For example, the 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) preferably has a number average molecular weight (Mn) of 500 or more, and preferably 20000 or less. If it is less than 500, the curing rate and the strength of the cured product may not be sufficient. In addition, if it exceeds 20000, there is a possibility that it may not be more suitable in terms of wettability with the substrate, mixing time when adjusting the resin composition, workability at the time of coating due to high viscosity, Furthermore, for example, there is a possibility that warpage of a laminate obtained by applying and curing to a plastic substrate cannot be sufficiently reduced. The number average molecular weight is more preferably in the range of 1000 to 20000, still more preferably 1500 to 10,000.

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. .

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 monomer represented by the above formula (2) can be produced by a usual method. For example, in the above formula (2), when R ¹ is an ethylene group and m is 1, a metal salt of (meth) acrylic acid and 2-halogenoethyl vinyl ether are condensed, or methyl (meth) acrylate and , 2-hydroxyethyl vinyl ether can be transesterified, or (meth) acrylic acid halide and 2-hydroxyethyl vinyl ether can be condensed. In the above formula (2), when R ¹ is an ethylene group and m is 2, a metal salt of (meth) acrylic acid and 2- (2-halogenoethoxy) ethyl vinyl ether are condensed or (meta ) By transesterifying methyl acrylate with 2- (2-hydroxyethoxy) ethyl vinyl ether or condensing (meth) acrylic acid halide with 2- (2-hydroxyethoxy) ethyl vinyl ether, Can be manufactured.

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 excellent curability, high cross-linking density of the cured product, excellent surface hardness, and low curing 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.

In the compound (b), the glass transition temperature of a single cured product is 15 to 100 ° C. If it is less than 15 ° C, permanent deformation such as compression marks and dents cannot be sufficiently suppressed, and if it is greater than 100 ° C, warping cannot be sufficiently prevented, and in any case, long-term storage stability is achieved. There is a possibility that a cured product having excellent properties cannot be obtained. Preferably it is 35 degreeC or more, More preferably, it is 40 degreeC or more, More preferably, it is 90 degreeC or less, More preferably, it is 80 degreeC or less.
The glass transition temperature here is a value obtained by a dynamic viscoelasticity measurement method under the above measurement conditions in the same manner as described above for a cured product obtained by curing the above compound (b) alone. The temperature of the maximum tan δ value is adopted.

The compound (b) further has an elastic modulus at 25 ° C. of a single cured product of 150 to 2000 MPa. If it is less than 150 MPa, permanent deformation such as compression marks and dents cannot be sufficiently suppressed, and if it is greater than 2000 MPa, warping cannot be sufficiently prevented, and in either case, long-term storage stability is achieved. There is a possibility that an excellent cured product cannot be obtained. Preferably it is 300 MPa or more, More preferably, it is 700 MPa or more. Moreover, Preferably it is 1700 MPa or less, More preferably, it is 1500 MPa or less, More preferably, it is 1300 MPa or less.
Here, the elastic modulus means storage elastic modulus (25 ° C.), and similarly to the glass transition temperature, the cured product obtained by curing the compound (b) alone is operated under the measurement conditions. It is a value obtained by a dynamic viscoelasticity measurement method.

The (meth) acrylate compound (c) is not particularly limited as long as it is a (meth) acrylate compound other than the components (a) and (b), but can be co-cured with the components (a) and / or (b). Preferably, the compound is in the form of a monomer (monomer). For example, the vinyl monomer represented by the general formula (2) described above, the following compounds, and the like can be given.
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- Hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxydiethylene glycol (meth) acrylate, butoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, trifluoroethyl (meth) Monofunctional (meth) acrylate compounds such as acrylate and perfluorooctylethyl (meth) acrylate;

Ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 3- Such as methyl-1,5-pentanediol di (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, di (meth) acrylic acid adduct of bisphenol A diglycidyl ether, etc. Bifunctional (meth) acrylate compounds; trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (Meth) acrylic acid derivatives such as trifunctional or more (meth) acrylate compound of meth) acrylate;

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, (meth) acrylic acid 2-vinyloxyethyl, 2- (2-vinyloxyethoxy) ethyl (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate , Tri (meth) acrylate of ethylene oxide adduct of trimethylolpropane, (meth) acrylic derivative having an ether structure such as di (meth) acrylate of ethylene oxide adduct of bisphenol A;

As the (meth) acrylate compound (c), among the compounds described above, the vinyl monomer represented by the general formula (2) is used from the viewpoint of good adhesion to a commonly used polycarbonate substrate. It is preferable to include.

In the present invention, in addition to the components (a) to (c), one or more of the following unsaturated compounds may be included as other co-curable components.
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), (b) and (c) and the unsaturated compound. More preferably, it is 20 mass% or less, More preferably, it is 10 mass% or less.
Hereinafter, the components (a), (b) and (c) and the unsaturated compound are collectively referred to as “polymerizable component”. That is, the polymerizable component is composed of the components (a), (b) and (c), and may further contain the unsaturated compound. In other words, when the curable resin composition for optical disc of the present invention does not contain the unsaturated compound, it means a component comprising the components (a), (b) and (c), and the unsaturated compound is When included, it means a mixture of the components (a), (b) and (c) and the unsaturated compound.

The curable resin composition for optical disks of the present invention contains (d) a photopolymerization initiator as an essential component in addition to the components (a), (b) and (c) described above. By including, there exists an effect that it can be hardened rapidly by light irradiation.
As the above (d) photopolymerization initiator, a photo radical polymerization initiator that generates a polymerization initiating radical by irradiation with light and a photo cationic polymerization initiator that generates a polymerization initiating cation by irradiation with light are suitable. 1 type (s) or 2 or more types 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 for optical disks, the content of the photopolymerization initiator (d) is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of the polymerizable components. . If the amount is less than 0.1 parts by weight, the resin composition may not be sufficiently cured. If the amount exceeds 10 parts by weight, odor generation or coloring of the cured product may not be sufficiently suppressed, and the recyclability of the resin composition may be reduced. Or the long-term storage stability of the cured product may not be good. More preferably, it is 1-8 weight part, More preferably, it is 1-5 weight part.

In addition to the essential components (a) to (d) described above, the curable resin composition for optical disks of the present invention may 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.

It is preferable that the addition amount of the said ultraviolet absorber is 0.03-0.4 weight part with respect to 100 weight part of total amounts of the said polymeric component. More preferably, it is 0.03-0.3 weight part, More preferably, it is 0.05-0.2 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-toluoyl benzoyl peroxide, benzoyl peroxide, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydi Carbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethoxyhexyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-s-butyl Oxy dicarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate,

α, α′-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneo Decanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2- Ethyl hexanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexanoate, 1-cyclohexyl-1-methylethylperoxy 2-ethylhexanoate, t-hexylperoxy-2-ethyl Hexanoate, t-butylperoxy-2 -Ethylhexanoate, t-hexylperoxysopropyl monocarbonate, t-butylperoxysobutyrate, t-butylperoxymalate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy Laurate, 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 ruperoxyallyl monocarbonate, t-butyltrimethylsilyl peroxide, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 2,3-dimethyl-2,3-diphenylbutane System initiators;

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-me Lupropionamidine]] dihydrochloride, 2,2′-azobis [2-methyl-N- (phenylmethyl) propionamidine] dihydrochloride, 2,2′-azobis [2-methyl-N- (2-propenyl) ) Propionamidine] dihydrochloride, 2,2′-azobis [N- (2-hydroxyethyl) -2-methylpropionamidine]] dihydrochloride, 2,2′-azobis [2- (5-methyl-2) -Imidazolin-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-trimethyl) pen Tan), 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.);
Protic acids (for example, halogenocarboxylic acids, sulfonic acids, sulfuric acid monoesters, phosphoric acid monoesters, phosphoric acid diesters, polyphosphoric acid esters, boric acid monoesters, boric acid diesters, etc.) as bases (for example, Ammonia, monoethylamine, diethylamine, triethylamine, pyridine, piperidine, aniline, morpholine, cyclohexylamine, monoethanolamine, diethanolamine, triethanolamine, butylamine, etc.)
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.

If necessary, the curable resin composition for optical disks may use one or more of photosensitizers, photopolymerization accelerators, metal oxide particles, surface function modifiers, solvents and the like. it can.
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, SnO 2, 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 and the} like may be used, and one or more of these may be used. Can do. 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 optical disk curable resin composition may further include, as necessary, inorganic fillers, low shrinkage agents (reactive oligomers or polymers, non-reactive oligomers or polymers), color pigments, plasticizers, chains as necessary. Transfer agent, polymerization inhibitor, near infrared absorber, light stabilizer, antioxidant, flame retardant, matting agent, dye, defoaming agent, leveling agent, antistatic agent, dispersant, slip agent, surface modification 1 type (s) or 2 or more types, such as a quality agent, a thixotropic agent, 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.

The curable resin composition for an optical disk of the present invention comprises the above-described essential components (a) to (d) and the above-mentioned components included as necessary, and is mixed and stirred by a usual method. Obtainable.
The viscosity of such a resin composition is preferably 800 to 3500 mPa · s at 25 ° C. If it is outside this range, for example, when a protective layer of an optical disk is formed using the resin composition, the thickness of the protective layer may not be controlled to 100 μm ± 2 μm. Specifically, there is a possibility that the thickness of the protective layer at the center portion becomes thinner or the thickness of the protective layer at the end portion becomes thicker. More preferably, it is 900-3000 mPa * s, More preferably, it is 1000-2500 mPa * s.
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 for optical disks can be cured by irradiating 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 resin composition may be cured by heating as well as 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 resin composition may be further cured by irradiation with an electron beam as well as by irradiation with light. 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.

A cured product obtained by curing the above curable resin composition for optical disks is also one aspect of the present invention. The cured product is not only excellent in transparency, hardness, and remaining film properties, but also has a significant warpage. It is small, and permanent deformation (permanent deformation) due to pressure marks, dents and the like is sufficiently suppressed, and remarkably excellent in long-term storage stability. Therefore, the cured product is particularly useful as a layer (cured film) constituting the optical disc. An optical disk having a layer obtained by curing the curable resin composition for an optical disk as described above is also one aspect of the present invention.

The optical disc has a substrate, a reflective film for reflecting laser light for reading information, and a protective layer having a thickness of 20 to 150 μm in this order. The optical disc requires the substrate, the reflective film, and the protective layer in this order. As long as it is, it may have another functional layer, and may have another functional layer between these layers. As such an optical disc, a Blu-ray disc is particularly preferable.
As the optical disk, for example, a protective layer formed by curing the curable resin composition for an optical disk of the present invention is formed on a reflective film formed on a substrate (or a functional layer formed on the substrate). The term “on the reflective film” as used herein means not only a form in which a protective layer is directly laminated on the reflective film, but also a functional layer laminated on the reflective film, and the protective layer is laminated on the functional layer. It also means the form.

In the above optical disc, the curable resin composition for optical discs of the present invention can be suitably used as a material for forming a light transmission layer, but is particularly preferably used for forming a protective layer. 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 Realize a protective layer that satisfies all of the properties such as stability, dimensional stability, long-term storage stability (warping change during heating acceleration test, residual film property, small amount of permanent deformation such as pressure marks and dents) It becomes possible.

In recent years, in order to increase the recording capacity of an optical disc, a multilayer optical disc having two or more information recording layers has been developed. In such an optical disc, a transparent ultraviolet curable resin is used as an ultraviolet ray between information recording layers. A cured intermediate layer is formed. The curable resin composition for an optical disk of the present invention is particularly preferable as a material for forming a protective layer, but it is also preferable to use it as a material for forming this intermediate layer. That is, an optical disc having a protective layer and / or an intermediate layer obtained by curing the curable resin composition for an optical disc is one of the preferred embodiments of the present invention.

In addition, by using the above resin composition, a transparent protective layer (transparent cover layer) of an optical disk (optical recording medium) that is hard to damage a cured coating film can be formed. A layer such as an antistatic layer, a water repellent layer, an oil repellent layer, or a hard coat layer may be formed on the layer.

The cured product (layer obtained by curing) of the resin composition is preferably such that the storage elastic modulus E ′ at 25 ° C. is 1200 to 2100 MPa. If it is greater than 2100 MPa, the warpage of the cured product may not be sufficiently suppressed, and if it is less than 1200 MPa, permanent deformation due to pressure marks or dents may not be sufficiently suppressed. More preferably, it is 1400 MPa or more, More preferably, it is 1600 MPa or more, Especially preferably, it is 1700 MPa or more, Most preferably, it is 1800 MPa or more. Moreover, it is more suitable that it is 2000 MPa or less.

The cured product (layer obtained by curing) preferably has a loss tangent tan δ at 25 ° C. of 0.03 to 0.12. If it is greater than 0.12, the long-term storage stability of the cured product may not be sufficient, and permanent deformation due to pressure marks or dents may not be sufficiently suppressed, and if it is less than 0.03, curing may occur. There is a possibility that the warping of the object cannot be sufficiently suppressed. More preferably, it is 0.1 or less, More preferably, it is 0.09 or less, Most preferably, it is 0.07 or less.

It is preferable that the cured product (layer formed by curing) further has a glass transition temperature (Tg) of 60 to 85 ° C. If it is higher than 85 ° C., the warpage of the cured product may not be sufficiently suppressed, and if it is lower than 60 ° C., there is a possibility that permanent deformation due to pressure marks or dents cannot be further sufficiently suppressed. More preferably, it is 65 degreeC or more, More preferably, it is 70 degreeC or more, Most preferably, it is 74 degreeC or more.

Here, the storage elastic modulus E ′, loss tangent tan δ, and glass transition temperature are dynamic viscoelasticity of the cured product obtained by curing the curable resin composition for optical disks by the following curing method under the following measurement conditions. And the value obtained at 25 ° C. is adopted. In addition, the glass transition temperature shall employ the temperature of the maximum tan δ value.
<Curing method>
On a polycarbonate substrate (PC substrate) having a thickness of 1.1 mm and a diameter of 120 mm, a curable resin composition for an optical disk is applied with a thickness of 100 μm using a spin coater. The obtained PC board was first irradiated with a flash twice at a lamp height of 2 cm under a nitrogen atmosphere using a UV irradiator having a xenon flash UV lamp (model RC-742, manufactured by Xenon, USA). The flash is irradiated 30 times at a lamp height of 2 cm to complete the curing.
<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.

The cured product (cured layer) is also preferably such that the light transmittance at 405 nm at a thickness of 100 μm is 85% or more. If it is less than 85%, the transparency is not sufficient, and errors may increase when reading recorded information, so that there is a possibility that the optical disk cannot be made more suitable. More preferably, it is 88% or more, More preferably, it is 89% or more.
The light transmittance can be measured with a spectrophotometer.

The cured product (a layer obtained by curing) preferably has a mass loss (mass loss) rate of 0.1 to 2% by mass when held in an oven at 70 ° C. for 100 hours. The mass decrease is considered to be caused by uncrosslinked polymerizable monomer components, initiator residues and decomposition products thereof, low molecular weight additives, etc., but when the content is larger than 2% by mass, the volatile components are cured. There is a possibility that the error generation at the time of reading information recorded due to bleed-out to the surface of the object or a change in the thickness of the protective layer cannot be sufficiently reduced, and the long-term storage stability of the optical disk may not be good. Further, in order to make the mass reduction rate less than 0.1% by mass, a drying (decompression) step of the cured product is required, resulting in an increase in cost. That is, by setting the weight loss rate within the above range, for example, the optical disk is less likely to have a decrease in surface accuracy over time and storage stability is improved, and can be used and stored in an automobile or the like. . 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 μ ± 2 μm.

The said hardened | cured material (layer formed by hardening) has a thickness of 20-150 micrometers. The upper limit value of the thickness is preferably 120 μm, more preferably 105 μm, and the lower limit value is preferably 50 μm, and more preferably 70 μm. That is, the thickness of the protective layer or the like in the optical disc may be 20 to 150 μm, more preferably 50 to 105 μm, and still more preferably 70 to 120 μm.
Since the cured product (layer formed by curing) is also formed from the curable resin composition for optical disks of the present invention, the thickness change after curing can be controlled within ± 2 μm.

The curable resin composition for an optical disk of the present invention has the above-described configuration, is excellent in transparency, has extremely small warpage, and sufficiently suppresses permanent deformation such as a press-contact mark and a dent, and is stable for a long time. A cured product having excellent properties can be provided. If such a resin composition is used for an optical disc, more reliable recording / reproduction can be realized, and therefore it is particularly useful as a layer forming material for protective layers and intermediate layers constituting various optical discs such as Blu-ray discs. .

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 elastic modulus of the polymer were measured by the methods described above. Further, various physical properties in Examples and Comparative Examples were evaluated by the following methods.

<Evaluation methods for various physical properties>
(1) Resin Composition Viscosity The value obtained by measuring the obtained resin composition using a B-type viscometer (model “RB80L”, manufactured by Toki Sangyo Co., Ltd.) under the condition of a temperature of 25 ° C. was adopted.
(2) Transparency of protective layer Only the protective layer (cured film (cured product) of the resin composition) is peeled off from the obtained substrate / protective layer laminate with a predetermined dimension, and the light transmittance at 405 nm is measured by spectroscopy. Measurement was performed using a photometer (model UV-3100, manufactured by Shimadzu Corporation). Air was employed as a blank. Next, the calculated light transmittance value was evaluated according to the following criteria.
◎: Transmittance is 89% or more ○: Transmittance is 85% or more ×: Transmittance is less than 85%

(3) Mass loss rate of protective layer (mass reduction rate)
Only the protective layer (cured film (cured product) of the resin composition) was peeled off from the obtained substrate / protective layer laminate at a predetermined size, and before and after the heating acceleration test (held in an oven at 70 ° C. for 100 hours). The weight loss rate (%) was calculated by [(mass before test−mass after test) / mass before test × 100]. Next, the calculated light transmittance value was evaluated according to the following criteria.
A: The weight loss rate is 1.0% or less. O: The weight loss rate exceeds 1.0% and is 2.0% or less. X: The weight loss rate exceeds 2.0%.
(4) Protective layer residual film heating acceleration test (held in an oven at 70 ° C. for 100 hours) The thickness of the protective layer was measured using a laser focus displacement meter, and the residual film ratio (%) was determined as [( Film thickness after heating acceleration test / film thickness before heating acceleration test) × 100], and the remaining film property was evaluated according to the following criteria.
○: Remaining film ratio is 98.0% or more and less than 102% ×: Remaining film ratio is less than 98.0% or 102% or more

(5) After placing the obtained substrate / protective layer laminate on a horizontal glass plate so that the protective layer (cured film (cured product) of the resin composition) is on the upper surface side. The radial tilt 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%. In addition, the radial tilt value of only the polycarbonate substrate before obtaining the laminate was −0.8 °, and warped on the side opposite to the protective layer. As the initial warpage increase amount, the warpage change amount before and after coating was adopted.
(6) Increase in warpage after heating acceleration test The obtained substrate / protective layer laminate was held in an oven at 70 ° C. for 100 hours, and further allowed to stand in an environment at 25 ° C. and 50% relative humidity for 24 hours. The radial tilt value was measured in the same manner as the initial warpage increase.
(7) Warpage Comprehensive Evaluation The warpage increase amount at the initial stage and the warpage increase amount after the heating acceleration test were added together, and the obtained warpage amount was evaluated according to the following criteria.
○: Less than 0.8 ° ×: 0.8 ° or more If there is a warp of 0.8 ° or more, it is difficult to improve to the warp standard even if the manufacturing process is improved or the transparent cover resin is improved. There is a risk of becoming.

(8) Protective layer Storage elastic modulus E ′ at 25 ° C.
Only the protective layer (cured film (cured product) of the resin composition) is peeled off from the obtained substrate / protective layer laminate with predetermined dimensions, and the tensile mode, the frequency is 1 Hz, the clamp distance is 25 mm, and the amplitude is 0.1%. Then, the dynamic viscoelasticity was measured under the condition of a heating rate of 5 ° C./min, and the obtained value of the storage elastic modulus E ′ at 25 ° C. was adopted.
(9) Protective layer Loss tangent tan δ at 25 ° C
The value obtained by the same measurement method and conditions as the storage elastic modulus E ′ at 25 ° C. was adopted.
(10) Protective layer Glass point transfer temperature (Tg)
This is a value obtained by the same measurement method and conditions as the storage elastic modulus E ′ at 25 ° C., and the temperature of the maximum tan δ value was adopted.
(11) Permanent deformation (μm)
Using the obtained substrate / protective layer laminate, using a micro-compression tester (manufactured by Shimadzu Corporation, model MCT-W500), as test conditions, a used flat indenter diameter of 50 μm, a load speed of 20 mN / sec, a maximum load of 300 mN, A value obtained by measuring the amount of deformation remaining in the laminate when the holding time at the maximum load was 90 seconds, the unloading speed was 20 mN / sec, and the holding time after complete unloading was 90 seconds was adopted.
In addition, when the amount of permanent deformation exceeds 1 μm by this test, the long-term storage stability may be inferior due to pressure marks or dents.

Production Example 1
150 g of ethyl acetate was added to a four-necked flask equipped with a stir bar, thermometer, dropping line, and nitrogen / air mixed gas introduction tube, and the temperature was raised to 45 ° C. After heating, a mixture of 100 g of 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA, Nippon Shokubai Co., Ltd.) and 100 g of cyclohexyl vinyl ether (CHVE), 25 g of ethyl acetate and 13 mg of phosphotungstic acid, Were respectively added dropwise over 3 hours to carry out polymerization. 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 (VEEA-CHVE) -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. Further, the number average molecular weight (Mn) of the obtained vinyl polymer was 2840, the molecular weight distribution (Mw / Mn) was 1.62, the glass transition temperature was 50 ° C., and the elastic modulus was 1110 MPa.

Production Example 2
150 g of ethyl acetate was added to a four-necked flask equipped with a stir bar, thermometer, dropping line, and nitrogen / air mixed gas introduction tube, and the temperature was raised to 50 ° C. After the temperature increase, 200 g of 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA, manufactured by Nippon Shokubai Co., Ltd.), a mixed solution of 25 g of ethyl acetate and 13 mg of phosphotungstic acid was added dropwise over 3 hours and polymerized. Went. 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 (VEEA) -1”) was obtained. 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. Further, the number average molecular weight (Mn) of the obtained vinyl polymer was 2210, the molecular weight distribution (Mw / Mn) was 1.60, the glass transition temperature was 74 ° C., and the elastic modulus was 1660 MPa.

Example 1
50 parts by weight of urethane acrylate (trade name “purple UV-7000B”, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 20 parts by weight of tricyclodecane diacrylate (trade name “light acrylate DCP-A”, manufactured by Kyoeisha Chemical Co., Ltd.), Isobol Nyl acrylate (trade name “light acrylate IB-X”, manufactured by Kyoeisha Chemical Co., Ltd.) 20 parts by weight, 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA, manufactured by Nippon Shokubai Co., Ltd.), 10 parts by weight, and photopolymerization As an initiator, 2 parts by weight of oligo {2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone} (trade name “Escure ONE”, manufactured by Lamberti Co.) was mixed and stirred. Thus, a curable resin composition for optical disks was prepared.

Next, a curable resin composition for an optical disk was 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 board was first irradiated with a flash twice at a lamp height of 2 cm under a nitrogen atmosphere using a UV irradiator having a xenon flash UV lamp (model RC-742, manufactured by Xenon, USA). Curing was completed by irradiating a flash 30 times at a lamp height of 2 cm. In addition, the irradiation integrated light quantity in 320-390 nm was about 0.9 J / cm < ² >. When the thickness of the protective layer was measured using a laser focus displacement meter, it was 100 ± 2 μm.
The obtained curable resin composition for optical disks and the substrate / protective layer laminate were evaluated. The results are shown in Table 1-1.

Examples 2-13, Comparative Examples 1-9
In the same manner as in Example 1, the components were mixed and stirred at the ratios shown in Tables 1-1 to 1-3 to obtain a curable resin composition for optical disks. The obtained resin composition was evaluated by the above evaluation method. The evaluation results are shown in Tables 1-1 to 1-3.

Abbreviations in Tables 1-1 to 1-3 are as follows. In the following compounds, the Tg shown in parentheses means the Tg of the cured product of the homopolymer (homopolymer) in the case of a monomer, and in the case of an oligomer or polymer, it was cured alone. It means Tg of the cured product. The elastic modulus of the oligomer or polymer means the storage elastic modulus of the single cured product.
IB-XA: Isobornyl acrylate (trade name “Light acrylate IB-XA”, manufactured by Kyoeisha Chemical Co., Tg: 88 ° C.)
IB-XM: Isobornyl methacrylate (trade name “Light Ester IB-X”, manufactured by Kyoeisha Chemical Co., Tg: 110 ° C.)
DCP-A: Tricyclodecane diacrylate (trade name “light acrylate DCP-A”, manufactured by Kyoeisha Chemical Co., Tg: 187 ° C.)
DCP-M: Tricyclodecane dimethacrylate (trade name “Light Ester DCP-M”, manufactured by Kyoeisha Chemical Co., Tg: 214 ° C.)
CD-536: Compound represented by the above formula (3) (2- (meth) acryloyloxyisobutyl-5-ethyl-5- (meth) acryloyloxymethyl-1,3-dioxane, manufactured by Sartomer, Tg: 78 ℃)

UV-7000B: urethane acrylate (manufactured by Nippon Synthetic Chemical Industry, Tg: 50 ° C., elastic modulus: 870 MPa)
CN-9893: Urethane acrylate (Sartomer, Tg: 40 ° C., elastic modulus: 370 MPa)
CN-981: Urethane acrylate (Sartomer, Tg: 37 ° C., elastic modulus: 770 MPa)
UV-6640B: urethane acrylate (manufactured by Nippon Synthetic Chemical Industry, Tg: 34 ° C., elastic modulus: 130 MPa)
UV-6100B: urethane acrylate (manufactured by Nippon Synthetic Chemical Industry, Tg: 12 ° C., elastic modulus: 250 MPa)
CN-2302: Polyester acrylate (manufactured by Sartomer, Tg: 47 ° C., elastic modulus: 780 MPa)
CN-9090: Urethane acrylate (Sartomer, Tg: 44 ° C., elastic modulus: 1260 MPa)
P (VEEA-CHVE) -1: Vinyl polymer obtained in Production Example 1 (Tg of cured product: 50 ° C., elastic modulus: 1110 MPa)
P (VEEA) -1: Vinyl polymer obtained in Production Example 2 (Tg of cured product: 74 ° C., elastic modulus: 1660 MPa)

Bis4EO-A: Diacrylate of ethylene oxide adduct of bisphenol A (trade name “Light acrylate BP-4EA”, manufactured by Kyoeisha Chemical Co., Ltd.)
BP4PO-A: Diacrylate of propylene oxide adduct of bisphenol A (trade name “Light acrylate BP-4PA”, manufactured by Kyoeisha Chemical Co., Ltd.)
Bis10EO-A: Diacrylate of ethylene oxide adduct of bisphenol A (trade name “SR-602”, manufactured by Sartomer)
Bis4EO-M: Dimethacrylate of ethylene oxide adduct of bisphenol A (trade name “BPE-200”, manufactured by Shin-Nakamura Chemical Co., Ltd.)
Bis6EO-M: Dimethacrylate of ethylene oxide adduct of bisphenol A (trade name “SR-541”, manufactured by Sartomer)
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.)
AA-6: Methacrylate-based reactive oligomer reducing agent (manufactured by Toa Gosei Co., Ltd.)
VEEA: 2- (2-vinyloxyethoxy) ethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.)

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

From Examples and Comparative Examples in Tables 1-1 to 1-3, the curable resin composition for an optical disk of the present invention is obtained by using (a) a homopolymer cured product having a glass transition temperature of 50 ° C. or higher. And / or (meth) acrylate compound having an aliphatic heterocyclic structure, (b) urethane (meth) acrylate compound, polyester (meth) acrylate compound, epoxy (meth) acrylate compound, and (meth) acryloyl in the side chain It is at least one compound selected from the group consisting of an oligomer or polymer having a group, the molecule has two or more radically polymerizable unsaturated groups, and the glass transition temperature of a single cured product is 15 to 100 ° C. And a compound having an elastic modulus at 25 ° C. of 150 to 2000 MPa (excluding a compound corresponding to (a)), and (c) the (a) And (meth) acrylate compounds other than (b) with respect to 100% by mass of the total amount of these components (a), (b) and (c), respectively (a) 20 to 55% by mass, (b) 15 -65% by mass, (c) 5-40% by mass, and (d) a composition containing a photopolymerization initiator exhibits advantageous effects in terms of warpage after curing and permanent deformation. It was confirmed that it is remarkable. This will be described below.

That is, all of the resin compositions of Examples 1 to 13 are the resin compositions of the above-mentioned form, but are excellent in transparency and residual film property and have a significantly improved mass reduction rate, and are further permanent. The amount of deformation was 0.23 to 0.88 μm, and the total amount of warpage increase was 0.4 to 0.7 °, the warpage was extremely small, and permanent deformation such as pressure marks and dents was sufficiently suppressed. It turns out that it gives a hardened | cured material.

On the other hand, in the resin compositions of Comparative Examples 1, 4, 5, 6 and 7, 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 (c) is It is an example exceeding the upper limit of the numerical range of the invention, and Comparative Examples 1, 5, and 7 are examples in which the elastic modulus of the single cured product of the component (b) is lower than the lower limit of the range of the present invention. In this case, although the total amount of the increase in warpage is small, the permanent deformation is extremely large as 2.70 to 3.42 μm, compared with the cured products obtained by the resin compositions of Examples 1 to 13, It can be seen that the long-term storage stability is significantly inferior.

The resin composition of Comparative Example 2 is an example in which the elastic modulus of the single cured product of component (b) is below the lower limit of the range of the present invention, and the resin composition of Comparative Example 3 is a single cured component of component (b). This is an example in which the glass transition temperature of the product falls below the lower limit of the range of the present invention. In these cases as well, the total amount of increase in warpage is small, but the amount of permanent deformation is very large at 2.92 to 4.48 μm. Therefore, it turns out that long-term storage stability is remarkably inferior compared with the hardened | cured material obtained by the resin composition of Examples 1-13 in any case.

The resin compositions of Comparative Examples 8 and 9 are examples that do not contain the component (c). In this case, although the amount of permanent deformation is small, the total amount of increase in warpage is 1.2 to 1.3 °. Even if the manufacturing process is devised and the protective resin is improved, it is expected that it will be difficult to improve the warpage.

As described above, for the first time by making the resin composition of the above configuration, not only is it excellent in transparency and residual film properties and the mass reduction rate is reduced, but also warpage is remarkably small, and pressure marks and dents, etc. It can be said that it was confirmed that a particularly remarkable effect that a cured product in which the permanent deformation of the material was sufficiently suppressed can be provided can be exhibited.

Claims (5)

A curable resin composition used for an optical disc having a substrate, a reflective film that reflects a laser beam for reading information, and a protective layer having a thickness of 20 to 150 μm in this order,
The curable resin composition is
(A) a (meth) acrylate compound having an alicyclic structure and / or an aliphatic heterocyclic structure, wherein the homopolymer cured product has a glass transition temperature of 50 ° C. or higher;
(B) 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 (meth) acryloyl groups in the side chains. A compound having two or more radically polymerizable unsaturated groups in the molecule, a glass transition temperature of a single cured product of 15 to 100 ° C., and an elastic modulus at 25 ° C. of 150 to 2000 MPa ( However, the compound corresponding to (a) component is excluded.)
(C) (meth) acrylate compounds other than the components (a) and (b)
(A) 20 to 55% by mass, (b) 15 to 65% by mass, and (c) 5 to 40% by mass with respect to the total amount of these (a), (b) and (c) components of 100% by mass. And
The curable resin composition further comprises (d) a photopolymerization initiator. The (meth) acrylate compound (a) includes (a1) a monofunctional (meth) acrylate compound having an alicyclic structure and / or an aliphatic heterocyclic structure, and (a2) an alicyclic structure and / or an aliphatic heterocyclic ring. The curable resin composition for an optical disk according to claim 1, which is a mixture with a polyfunctional (meth) acrylate compound having a structure. The curable resin composition for optical disks according to claim 1, wherein the curable resin composition has a viscosity at 25 ° C. of 800 to 3500 mPa · s. A cured product obtained by curing the curable resin composition for an optical disk according to claim 1. An optical disc comprising a layer obtained by curing the curable resin composition for an optical disc according to claim 1.