WO2010109615A1

WO2010109615A1 - Curable resin composition for optical disks, and optical disk

Info

Publication number: WO2010109615A1
Application number: PCT/JP2009/055994
Authority: WO
Inventors: 松田　安弘; 川田　雄一; 裕己橘
Original assignee: 株式会社日本触媒
Priority date: 2009-03-25
Filing date: 2009-03-25
Publication date: 2010-09-30

Abstract

Disclosed is a curable resin composition for optical disks, and an optical disk that uses same as a protective layer, that has high transparency, that makes possible highly reliable recording and reproduction, and that has excellent long-term storage stability (that is, exhibiting low warpage in high-temperature environment and low-temperature storage testing, and a small amount of permanent changes such as indentation or residual film formation in high-temperature environments). The curable resin composition for optical disks provides a reflective film on a substrate so that laser light can be reflected for the reading of information, and a protective layer on the aforementioned reflective film which has a thickness between 20 μm and 150 μm. The resin composition includes an oligomer and/or a polymer having a radical polymerizable group, an additive-containing polyfunctional (meth)acrylic acid ester, and a photopolymerization initiator. If the radical polymerizabile unsaturated group equivalent (g/eq) in the aforementioned curable resin composition is represented as A and the content (mass%) of the additive-containing (meth)acrylic acid ester in the aforementioned curable resin composition is represented as B, then 6.6 ≤ A ÷ B ≤ 35.

Description

Curable resin composition for optical disc and optical disc

The present invention relates to a curable resin composition for optical disks and an optical disk.

In recent years, high-definition digital high-definition broadcasting has started, and large-screen LCDs and plasma TVs with high image quality compatible with full high-definition have become widespread. However, a DVD (digital versatile disc), which is a conventional optical recording medium, has a small recording capacity, and therefore cannot record a high-quality moving image for a long time. To meet this demand, Blu-ray Disc (registered trademark), which records and plays back information with blue laser light, is developed and sold as a new optical recording medium standard that has a recording capacity more than five times that of DVD. It came to be.

In this new standard, blue laser light having a wavelength of 405 nm is employed to increase the capacity of the optical recording medium. Furthermore, the numerical aperture (NA) of the recording / reproducing optical system objective lens is increased to 0.85, the laser beam spot diameter during recording / reproducing is reduced to about 0.44 times that of DVD, and the signal is reduced. By reducing the recorded track pitch (interval) to about 0.43 times, a large recording capacity of 5 times or more is realized.

Another technology that has been adopted to increase the capacity will be explained. In the optical recording medium, a protective layer is provided on the disk surface viewed from the laser incident side in order to protect the reflective film and the recording layer. The thickness of this protective layer (distance between the disk surface and the signal recording surface) was about 600 μm for DVD, but is considerably thin, about 100 μm for Blu-ray Disc. In this way, Blu-ray discs can reduce recording laser beam spot distortion (bokeh) caused by tilting the disc surface due to disc warp, etc., by reducing the thickness of the protective layer, and achieve highly reliable recording and playback. I am doing so.

Japanese Patent Application Laid-Open No. 2006-351102 describes that the thickness of the protective layer is required to be highly uniform because unevenness in the thickness of the protective layer (light transmission film) causes a serious problem in recording and reproducing information. Has been. Japanese Patent Application Laid-Open No. 2007-115356 describes the necessity of controlling the thickness of the protective layer (transparent cover layer) to 100 μm ± 2 μm. Japanese Patent Application Laid-Open No. 2008-126518 discloses that a laser spot position may fluctuate due to scratches (permanent deformation) such as dents generated in an optical recording medium, which may cause problems in recording and reproducing information. Is described. From the viewpoint of long-term stable information recording and reproduction, it is desired that the change in the protective layer thickness is small when the optical recording medium is stored. Japanese Patent Application Laid-Open No. 2000-322768 describes a technique for preventing the protective layer (light transmission layer) from being scratched or deformed so as not to hinder the recording and reproduction. As a method of measuring the amount of deformation, a method of measuring the load and displacement during deformation while pushing a minute diamond indenter is adopted.

In JP-A-2002-157782 and JP-A-2003-132596, when stored in a high-temperature / high-humidity environment or a low-temperature environment, if the optical recording medium is warped, the loading of the drive device is hindered. In addition, since a reading error occurs when a warp accompanied by a twist occurs, it is described that an optical recording medium with a small warp occurring in various environments is required.

There are mainly two methods for forming the protective layer. There are a sheet bonding method in which a polycarbonate sheet is bonded with an ultraviolet curable adhesive, and a spin coating method in which an ultraviolet curable resin is applied by spin coating and the resin is cured by irradiating ultraviolet rays. At present, the spin coating method has become the mainstream in terms of cost. However, when the protective layer is formed using an ultraviolet curable resin, in addition to the above-mentioned film thickness uniformity being required, the optical recording medium is warped mainly due to the curing shrinkage of the ultraviolet curable resin. Happens. For this reason, when a method of applying and curing the ultraviolet curable resin by previously warping the recording medium substrate in the opposite direction to the warp caused by the curing shrinkage of the ultraviolet curable resin, correction by a reproducing / recording device, etc. May be performed. However, if the warpage exceeds an allowable range (correctable range), accurate data recording and reproduction on the optical recording medium may not be possible, and it may not be possible to insert / remove to / from the reproduction / recording apparatus. In addition, this warpage is not only required to have a small initial warpage, but also does not increase during a test to confirm long-term stability (storage test in a high temperature environment or a low temperature environment). Small).

Japanese Patent Application Laid-Open No. 2003-263780 discloses an optical disk having a protective layer (light transmissive layer) excellent in transparency, abrasion resistance, and mechanical properties, with a tensile elastic modulus of the protective layer in a specific range. It is described that it is desirable to do. Japanese Patent Application Laid-Open No. 2007-217134 discloses an optical recording medium having excellent dimensional stability against changes in the environment of a cured coating film obtained by ultraviolet irradiation. However, in an optical disc having a protective layer (light transmissive layer) on the reflective film (for example, a Blu-ray disc that reads information with blue laser light), long-term storage stability (high temperature environment or low temperature environment) In order to reduce the amount of permanent deformation due to the low warp in the storage test and the remaining film property under a high temperature environment) and the dent after the protective layer is pushed in, further improvement needs to be studied.

On the other hand, various studies on the protective layer have been conducted. For example, Japanese Patent Application Laid-Open Nos. 2006-4458 and 2003-263780 disclose that an optical disk having a protective layer (light transmissive layer) excellent in transparency and mechanical properties is used as a protective layer for an optical disk. It is described that it is desirable that the tensile modulus of the layer be in a specific range. Japanese Patent Application Laid-Open No. 2007-102980 discloses that the thickness of the protective layer and the thickness of the protective layer at 30.degree. It is described that the product with the elastic modulus is not more than a specific value. However, when a hard hard coat layer is formed on a protective layer having a low elastic modulus, a crack may occur in the hard coat layer depending on use conditions, which has been a problem.

Thus, in an optical disc having a protective layer (light transmission layer) on the reflective film (for example, a Blu-ray disc that reads information by blue laser light), the protective layer has a low-viscosity resin composition that does not substantially contain an organic solvent. When the elastic modulus is low, the hard coat material needs to be further improved in order to prevent deformation of the optical disk and dents and cracks after being pushed in from the hard coat layer.

Under the circumstances described above, the problems to be solved by the present invention are a reflective film for reflecting laser light for reading information on a substrate, and a protective layer (transparent cover layer) having a thickness of 20 μm to 150 μm on the reflective film. ) (For example, a Blu-ray disc that reads information with blue light having a wavelength of around 400 nm) can be recorded and played back with high transparency and reliability, and can be stored for a long period of time (high temperature environment or low temperature). The present invention provides a curable resin composition for optical discs that is excellent in low warpage in a storage test under an environment and a residual film property under a high temperature environment) and has a small amount of permanent deformation such as dents. An object of the present invention is to provide an optical disc using a cured product as a protective layer.

As a result of intensive studies, the inventors of the present invention have set the radical polymerizable unsaturated group equivalent and the content of specific (meth) acrylates in a specific range in the curable resin composition for optical discs. High transparency, long-term storage stability (low warpage in storage tests in high and low temperature environments, residual film properties in high temperature environments), and permanent areas such as dents after pressing the protective layer The present invention was completed by finding that an optical disk with a small amount of deformation could be obtained. Moreover, if the composition is adjusted so that the relationship between the amount of the radical polymerizable unsaturated group in the curable resin composition and the specific (meth) acrylic acid ester is within a certain range, the curable resin composition is cured. Whether the cured product obtained has a high or low elastic modulus, the amount of permanent deformation due to the dent generated after the protective film is pushed in becomes extremely small and can be suitably used for an optical disc.

That is, the curable resin composition for an optical disk of the present invention is present on a base and a reflective film for reflecting information-reading laser light, and on the reflective film, in order to solve the above problems. And a curable resin composition for use in an optical disc having a protective layer having a thickness of 20 μm or more and 150 μm or less, comprising urethane (meth) acrylate, epoxy (meth) acrylate, and polyester (meth) acrylate. An oligomer and / or polymer having at least one radically polymerizable group selected, an alkylene oxide adduct-containing polyfunctional (meth) acrylate ester or a caprolactone adduct-containing polyfunctional (meth) acrylate ester, and light A radically unsaturated unsaturated group in the curable resin composition. Amount (g / eq) of A, content of polyfunctional (meth) acrylic acid ester containing alkylene oxide adduct and polyfunctional (meth) acrylic acid ester containing caprolactone adduct in the curable resin composition (mass) %) Is B, 6.6 ≦ A ÷ B ≦ 35 is satisfied.

That is, the radical polymerizable unsaturated group equivalent (A) capable of forming a crosslinked structure is adjusted according to the content (B) of the adduct-containing (meth) acrylic acid ester into which the soft component can be introduced, and A ÷ By setting B within the above range, the obtained cured product has a desired hardness, and the amount of permanent deformation and warpage can be suppressed, and long-term storage stability can be improved.

The alkylene oxide adduct-containing polyfunctional (meth) acrylic acid esters are preferably diacrylates of bisphenol A alkylene oxide adducts.

The viscosity of the curable resin composition of the present invention at 25 ° C is preferably 800 mPa · s or more and 3500 mPa · s or less.

The storage elastic modulus E ′ at 25 ° C. of the cured product obtained by curing the curable resin composition is preferably 10 MPa or more and 150 MPa or less. Moreover, it is also a preferable aspect that the storage elastic modulus E ′ at 25 ° C. of the cured product obtained by curing the curable resin composition is 1200 MPa or more and 2100 MPa or less. Further, the light transmittance of each wavelength at a thickness of 100 μm of the cured product obtained by curing the curable resin composition is 85.0% or more at (X) 400 nm, and (Y) 35.0 at 380 nm. % Or more and 85.0% or less, and (Z) at 360 nm, preferably 0.1% or more and 50.0% or less. Furthermore, the curable resin composition preferably contains a polyfunctional (meth) acrylate and / or a multi-branched reactive compound.

The optical disk of the present invention is characterized by having a protective layer formed by curing the curable resin composition for optical disks. The optical disc is obtained by curing a resin composition for hard coat, which is formed directly on the protective layer and contains a multibranched reactive compound and / or a polymer having a reactive group in a side chain, and a polymerization initiator. It is preferable to have a hard coat layer obtained. The multibranched reactive compound is preferably a dendrimer and / or a hyperbranched polymer having two or more reactive groups at its terminals. Further, the optical disc is an alkylene oxide obtained from an alkylene oxide adduct in which an addition repeating unit per valence to a tetrahydric or higher polyhydric alcohol directly formed on the protective layer is n = 1 or 2. Addition-containing polyfunctional (meth) acrylic acid esters and / or caprolactone adducts obtained from caprolactone adducts with n = 1 or 2 per monovalent addition to a polyhydric alcohol having a valence of 4 or more It is also preferable to have a hard coat layer obtained by curing a resin composition for hard coat containing polyfunctional (meth) acrylic acid esters and a photopolymerization initiator.

Examples of the present invention are represented by ●, comparative examples are represented by ○, the radical polymerizable unsaturated group equivalent (g / eq) A in the curable resin composition is plotted on the horizontal axis, and the alkylene oxide adduct-containing polyfunctional is plotted on the vertical axis. It is the graph which plotted content (mass%) B of (meth) acrylic acid ester and caprolactone adduct containing polyfunctional (meth) acrylic acid ester. The line at the top of the graph indicates the boundary line (A / 6.6), and the line at the bottom of the graph indicates the boundary line (A / 35), that is, the upper and lower limits of the present invention.

<< Curable resin composition for optical disk >>
The curable resin composition for an optical disk of the present invention is present on a substrate and reflects a laser beam for reading information, and is present on the reflective film and has a thickness of 20 μm or more and 150 μm or less. A curable resin composition for use in an optical disc having a protective layer, wherein the radical polymerizable group is selected from the group consisting of urethane (meth) acrylate, epoxy (meth) acrylate, and polyester (meth) acrylate. Containing the oligomer and / or polymer, an alkylene oxide adduct-containing polyfunctional (meth) acrylic acid ester or caprolactone adduct-containing polyfunctional (meth) acrylic acid ester, and a photopolymerization initiator, Radical polymerizable unsaturated group equivalent (g / eq) in the resin composition is A, the curable resin composition When the content (% by mass) of the polyfunctional (meth) acrylic acid ester containing an alkylene oxide adduct and the polyfunctional (meth) acrylic acid ester containing a caprolactone adduct is B, 6.6 ≦ A ÷ B ≦ 35 is satisfied.

The components constituting the curable resin composition for optical disks of the present invention (hereinafter sometimes simply referred to as “curable resin composition”) will be described.

<Multifunctional (meth) acrylic acid ester containing alkylene oxide adduct and / or polyfunctional (meth) acrylic acid ester containing caprolactone adduct>
The curable resin composition of the present invention comprises an alkylene oxide adduct-containing polyfunctional (meth) acrylic acid ester and / or a caprolactone adduct-containing polyfunctional (meth) acrylic acid ester (hereinafter simply referred to as “adduct-containing (meta) )) (Sometimes referred to as “acrylate esters”). The adduct-containing (meth) acrylic acid esters are (meth) acrylic acid esters obtained by esterification with (meth) acrylic acid containing a ring-opened product of an oxyalkylene skeleton or caprolactone in the molecule. is there. By including these adduct-containing (meth) acrylic esters, the liquid viscosity and the physical properties of the cured product can be adjusted.

Examples of the alkylene oxide adduct-containing polyfunctional (meth) acrylic acid esters include di (meth) acrylate of bisphenol A ethylene oxide adduct, di (meth) acrylate of bisphenol A propylene oxide adduct, and cyclohexanedimethanol. Di (meth) acrylate of ethylene oxide adduct, di (meth) acrylate of propylene oxide adduct of cyclohexanedimethanol, di (meth) acrylate of ethylene oxide adduct of neopentyl glycol, di (meth) acrylate of propylene oxide adduct of neopentyl glycol (Meth) acrylate, di (meth) acrylate of ethylene oxide adduct of hexanediol, di (meth) acrylate of propylene oxide adduct of hexanediol, trimethylol Tri (meth) acrylate of Lopane's ethylene oxide adduct, tri (meth) acrylate of propylene oxide adduct of trimethylolpropane, tri (meth) acrylate of ethylene oxide adduct of glycerin, tri (meth) of propylene oxide adduct of glycerin Polyfunctional (meth) acrylic esters of alkylene oxide adducts of the above polyhydric alcohols such as acrylate, alkylene oxide-modified hydroxypivalic acid neopentyl glycol ester di (meth) acrylate, diethylene glycol di (meth) acrylate; And (2-vinyloxyethoxy) ethyl, a cationic polymer of 2- (2-vinyloxyethoxy) ethyl acrylate, and the like.

The number of repeating oxyalkylene skeletons in these alkylene oxide adduct-containing polyfunctional (meth) acrylic esters is preferably 4 or more and 16 or less, and more preferably 6 or more and 14 or less.

Examples of the polyfunctional (meth) acrylic acid esters containing caprolactone adduct include diacrylate of ε-caprolactone adduct such as neopentyl glycol hydroxypivalate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, and the like.

In addition, in this invention, you may have polyfunctional (meth) acrylate containing the addition product to which both alkylene oxide and caprolactone were added as addition product containing polyfunctional (meth) acrylic acid ester.

Among these, adduct-containing polyfunctional (meth) acrylic acid esters include di (meth) acrylate of ethylene oxide adduct of bisphenol A, tri (meth) acrylate of ethylene oxide adduct of trimethylolpropane, and neodymium hydroxypivalate. Diacrylate of ε-caprolactone adduct of pentyl glycol is preferred. Among these, di (meth) acrylate of ethylene oxide 10 mol adduct of bisphenol A is more preferable.

The compounding amount of the adduct-containing polyfunctional (meth) acrylic acid ester is preferably 8% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass, and 70% by mass in the curable resin composition. % Or less, more preferably 65% by mass or less, and still more preferably 60% by mass or less. When the blending amount is less than 8% by mass, a dent may be formed when the protective layer is pushed in. When it exceeds 70% by mass, the curing shrinkage rate and the internal distortion increase, for example, when the warp of the optical disk increases or the protection May crack or crack in the layer.

<Compound having radically polymerizable unsaturated group>
The curable resin composition of the present invention is not limited to the above-mentioned polyfunctional (meth) acrylic acid esters containing alkylene oxide adducts and / or polyfunctional (meth) acrylic acid esters containing caprolactone adducts. You may contain the material which has group.

Examples of the material having a radical polymerizable unsaturated group include an oligomer and / or polymer having at least one radical polymerizable group; a multi-branched reactive compound; and a polymerizable monomer. The compound having a radically polymerizable unsaturated group can be cured by active energy rays such as heat, ultraviolet rays, electron beams and gamma rays.

Examples of the oligomer and / or polymer having a radical polymerizable unsaturated group include a saturated or unsaturated polybasic acid or an anhydride thereof (for example, maleic acid, succinic acid, adipic acid, phthalic acid, isophthalic acid, Terephthalic acid, tetrahydrophthalic acid, etc.) and saturated or unsaturated polyhydric alcohols (eg, ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1 , 5-pentanediol, polyethylene glycol, polypropylene glycol, 1,4-dimethylolbenzene, trimethylolpropane, pentaerythritol, etc.) and (meth) acrylic acid to obtain polyester (meth) acrylate; Saturated polyhydric alcohols (eg For example, ethylene glycol, neopentyl glycol, polytetramethylene glycol, polyester polyol, polycaprolactone polyol, etc.), organic polyisocyanate (eg, tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, etc.), and hydroxyl group-containing (meth) acrylate (For example, urethane (meth) acrylate obtained by reaction with 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, etc.); Polysiloxane poly (meth) acrylate obtained by reaction with (meth) acrylic acid; multi-branched reactive (meth) acrylate compounds such as dendrimers and hyperbranched polymers And the like.

Examples of oligomers and / or polymers having both radical polymerizable groups and ion polymerizable groups include epoxy resins (for example, phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, trisphenol methane type). (Epoxy resin, polybutanediene-modified epoxy resin, alicyclic epoxy resin, brominated phenol novolak epoxy resin, brominated bisphenol A type epoxy resin, amino group-containing epoxy resin, etc.) and obtained by reaction with (meth) acrylic acid Epoxy (meth) acrylate; reaction of the above epoxy (meth) acrylate with a polybasic acid anhydride (eg, maleic anhydride, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, etc.) Resulting carboxylic acid-modified epoxy (meth) acrylate.

Among these, the curable resin composition of the present invention includes, as an oligomer and / or polymer having at least one radical polymerizable group, urethane (meth) acrylate, epoxy (meth) acrylate, and polyester (meth) acrylate. It is essential to include at least one selected from the group consisting of:

In particular, when urethane (meth) acrylate is used, the isocyanate component constituting the urethane (meth) acrylate is preferably a polyvalent isocyanate having an alicyclic skeleton or an aromatic ring skeleton, particularly preferably 2 having an alicyclic skeleton. Divalent isocyanate. Examples of the divalent isocyanate having an alicyclic skeleton include isophorone diisocyanate. The polyhydric alcohol component constituting the urethane (meth) acrylate is preferably a polyhydric alcohol having an oxyalkylene skeleton, and more preferably a dihydric alcohol. Examples of the dihydric alcohol having an oxyalkylene skeleton include oligoethylene glycol, oligopropylene glycol, oligobutylene glycol, and oligo (ethylene-propylene) glycol, and oligoethylene glycol and oligo (ethylene-propylene) glycol are particularly preferable. The number of repeating oxyalkylene skeletons is preferably 4 or more and 12 or less, and more preferably 6 or more and 10 or less. The hydroxyl group-containing (meth) acrylate component constituting the urethane (meth) acrylate is preferably a hydroxyl group-containing acrylate, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 1,4-butanediol monoacrylate, and the like. Of these, 2-hydroxyethyl acrylate is particularly preferred.

Further, the urethane (meth) acrylate may contain urethane (meth) acrylate in which an isocyanate component and a hydroxyl group-containing (meth) acrylate component are directly urethane-bonded in the composition. The preferred isocyanate component and hydroxyl group-containing (meth) acrylate component in the case where the isocyanate component and the hydroxyl group-containing (meth) acrylate component contain urethane (meth) acrylate directly bonded by urethane are the same as described above.

Urethane (meth) acrylate is a raw material isocyanate component of 15% by mass to 30% by mass, a raw material polyhydric alcohol component of 45% by mass to 65% by mass, and a raw material hydroxyl group-containing (meth) acrylate component in 100% by mass of the raw material composition. Is preferably 5% by mass to 40% by mass, the raw material isocyanate component is 18% by mass to 25% by mass, the raw material polyhydric alcohol component is 50% by mass to 60% by mass, and the raw material hydroxyl group-containing (meth) acrylate The component is more preferably 15% by mass or more and 32% by mass or less.

Moreover, when the isocyanate component and the hydroxyl group-containing (meth) acrylate component contain urethane (meth) acrylate in which the urethane bond is directly bonded, the content is 100 as the total of urethane (meth) acrylate having a polyhydric alcohol component. When it is defined as mass%, it is preferably 1 mass% or more and 20 mass% or less, and particularly preferably 5 mass% or more and 15 mass% or less.

The method for synthesizing urethane (meth) acrylate that can be used as a material having a radically polymerizable unsaturated group is not particularly limited. For example, a raw material isocyanate component and a raw material hydroxyl group-containing (meth) acrylate are reacted, and then a polyhydric alcohol component is used in this order. Method of reacting; Method of charging raw material isocyanate component, raw material hydroxyl group-containing (meth) acrylate, and polyhydric alcohol component in a batch; reacting raw material isocyanate component and polyhydric alcohol component, then hydroxyl group-containing (meth) acrylate The method of making it react is mentioned. Among these, a urethane in which the isocyanate component and the hydroxyl group-containing (meth) acrylate component are directly urethanized by using a method in which the raw material isocyanate component and the raw material hydroxyl group-containing (meth) acrylate are reacted and then reacted in the order of the polyhydric alcohol component. (Meth) acrylate can also be synthesized at the same time, which is particularly preferable because productivity is improved. In addition, when adopting a method in which the raw material isocyanate component and the raw material hydroxyl group-containing (meth) acrylate are reacted and then reacted in the order of the polyhydric alcohol component, the raw material hydroxyl group-containing (meth) acrylate is divided into initial addition and subsequent addition. It is also preferable to add partly the raw material hydroxyl group-containing (meth) acrylate after the addition of the polyhydric alcohol component.

When the curable resin composition contains an oligomer / polymer having a radical polymerizable group, the content thereof is preferably 20% by mass or more, more preferably 30% by mass or more, and 80% by mass in the curable resin composition. The following is preferable, and more preferably 70% by mass or less. Each of these components can be contained alone or in combination of two or more. If the total content is less than 20% by mass, the long-term storage stability of the optical disk may be inferior, and if it is more than 80% by mass, the viscosity is high and workability may be reduced.

The oligomer / polymer having a radical polymerizable group contained in the curable resin composition for optical disks can be arbitrarily selected. When the elastic modulus of a cured product obtained by curing the curable resin composition for an optical disk of the present invention is designed to be low, a cured product of a single oligomer / polymer having a radical polymerizable group (hereinafter referred to as “single cured product”). The glass transition temperature is preferably −10 ° C. or higher, more preferably −5 ° C. or higher, preferably 45 ° C. or lower, more preferably 40 ° C. or lower. Further, the elastic modulus at 25 ° C. of the single cured product is preferably 50 MPa or more, more preferably 55 MPa or more, preferably 900 MPa or less, more preferably 850 MPa or less, and still more preferably 800 MPa or less.

The single cured product is produced under the same conditions as those for curing the curable resin composition for optical disks. That is, after adding and mixing the photopolymerization initiator used in the curable resin composition for optical discs to the oligomer / polymer so as to have the same addition rate, curing conditions (light irradiation time, Curing is performed with the same irradiation height, irradiation amount, and cured product thickness). The glass point transition temperature is a value obtained by dynamic viscoelasticity measurement, and a temperature having a maximum tan δ value is adopted. As the measurement conditions, 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 are employed. When the glass point transition temperature of the single cured product exceeds 45 ° C., the warp of the optical disk may increase. When the glass point transition temperature of the single cured product is less than −10 ° C., the optical disk may be dented or the long-term storage stability may be deteriorated. The elastic modulus of the single cured product is a value obtained by dynamic viscoelasticity measurement using the single cured product obtained in the same manner, and is a value of the storage elastic modulus E ′ at 25 ° C. If the elastic modulus of the single cured product is less than 50 MPa, the long-term storage stability of the optical disk may be deteriorated. In particular, when the protective layer is pushed in, a dent may be formed. On the other hand, when the elastic modulus of the single cured product exceeds 900 MPa, the warp of the obtained optical disk may increase or the long-term storage stability may deteriorate.

On the other hand, when the elastic modulus of the cured product obtained by curing the curable resin composition for an optical disk of the present invention is designed to be high, the glass transition temperature of the single cured product is preferably 30 ° C. or higher, and 60 ° C. or lower. More preferably, it is 55 ° C. or less, more preferably 50 ° C. or less. Further, the elastic modulus at 25 ° C. of the single cured product is preferably 100 MPa or more, preferably 2000 MPa or less, more preferably 1500 MPa or less, and further preferably 1000 MPa or less.

When the glass point transition temperature of the single cured product exceeds 60 ° C. or the elastic modulus exceeds 2000 MPa, the warp of the optical disk may increase. Moreover, when the glass transition temperature of the single cured product is less than 30 ° C., the optical disk may be dented, and when the elastic modulus is less than 100 MPa, the long-term storage stability of the optical disk may be deteriorated. In particular, when the protective layer is pushed in, a dent may be formed. The glass transition temperature and elastic modulus employ the above-described measuring methods.

The elastic modulus of the single cured product is not particularly limited, and other than the above-described low elastic modulus and high elastic modulus can be adopted, but the above-described low elastic modulus is a particularly preferable embodiment.

<Vinyl polymer>
For the cured product obtained by curing the curable resin composition of the present invention, when a high hardness is required in terms of physical properties, a vinyl polymer having a repeating unit represented by the following formula (1) may be used. preferable. The vinyl polymer having a repeating unit represented by the following formula (1) is an adduct-containing polyfunctional (meth) acrylic acid ester when m ≧ 2, and m = 0 or 1 in the formula. In the case of the above, it is an oligomer / polymer having a radical polymerizable group.

[Wherein R ¹ is an alkylene group having 2 to 8 carbon atoms, R ² is a hydrogen atom or a methyl group, and m is a positive integer]

In the above formula (1), examples of the alkylene group having 2 to 8 carbon atoms represented by R ¹ include, for example, ethylene group, trimethylene group, propylene group, tetramethylene group, pentamethylene group, hexamethylene group, 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. There are m substituents represented by R ¹ in the above formula (1), but they may be the same or different.

In the above formula (1), m is a positive integer, preferably an integer of 1 to 20, more preferably an integer of 1 to 10, more preferably an integer of 1 to 5.

The vinyl polymer represented by the above formula (1) may be a copolymer having a structural unit derived from a cationically polymerizable monomer, and preferred embodiments of the copolymer and polymerization method described above can be employed.

<Multi-branch type reactive compound>
The multi-branched reactive compound is a three-dimensionally branched product prepared from a compound having one reactive group X in one molecule and two or more reactive groups Y capable of reacting with the reactive group X. Is a compound having a structure repeating (hereinafter sometimes referred to as “branched repeating unit”).

Such multi-branched reactive compounds differ greatly from conventional linear polymers, for example: (I) soluble in organic solvents and low viscosity; (II) amorphous materials; (III ) As the inside of the molecule becomes sparse and the outside becomes denser, the shape will not change depending on the environment and the shape will remain spherical; (IV) the density will be low; (V) there will be many end groups; Therefore, the multi-branch type reactive compound has, for example, (I) a high curing rate; (II) a coating film after curing is not easily damaged; (III) a warp after being applied to a substrate is small due to a small shrinkage rate. ; (IV) It has excellent toughness and is difficult to cause cracking and peeling of the coating film.

The hyperbranched reactive compound is a highly branched compound having a highly branched molecular skeleton composed of a dendrimer represented by the following formula (2) and / or a hyperbranched polymer represented by the following formula (3). Dendrimers and hyperbranched polymers with low regularity are preferred. In particular, dendrimers are capable of intensively arranging reactive functional groups on the outermost surface as compared with linear polymers generally used. Although hyperbranched polymers are not as good as dendrimers, they can introduce many reactive functional groups on the outermost surface and are excellent in curability.

A compound having a core part, having regular branch repeating units radially from the core part, and having two or more branch repeating units is referred to as a dendrimer. In the dendrimer that can be used as the multi-branched reactive compound, a part or all of the terminal groups (usually the reactive group Y) may be replaced with other reactive groups. A dendrimer that can be used as a multi-branched reactive compound requires that at least two or more terminal groups have reactivity. The terminal group is preferably a radical polymerizable double bond group, and more preferably a (meth) acryloyl group. Further, a part of the end group may be replaced with a non-reactive substituent.

The hyperbranched polymer that can be used as the multi-branched reactive compound has a constitution of a branched repeating unit like the dendrimer, but the core portion is not essential. In addition, the hyperbranched polymer that can be used as the multi-branched reactive compound may have partially missing portions, irregular or discontinuous portions in the branch repeating unit. In the hyperbranched polymer that can be used as the multi-branched reactive compound, a part or all of the plurality of terminal groups (usually the reactive group Y) may be replaced with other reactive groups. The hyperbranched polymer that can be used as the multi-branched reactive compound requires that at least two or more terminal groups have reactivity. The terminal group is preferably a radical polymerizable double bond group, and more preferably a (meth) acryloyl group. Further, a part of the end group may be replaced with a non-reactive substituent.

In the present invention, when a multi-branched reactive compound is used, the blending amount thereof is preferably 10% by mass or more and less than 90% by mass, more preferably 30% by mass or more and 70% by mass or less, in the curable resin composition. is there. When the blending amount of the multi-branched reactive compound is less than 10% by mass, the crosslinking density is lowered, so that the curing rate is lowered and the coating strength of the cured product may be insufficient. Moreover, when the compounding quantity of a multi-branch type reactive compound is 90 mass or more, when the curvature of the laminated body obtained by apply | coating to a base | substrate and making it harden | cure, a crack may arise in cured | curing material.

<Monofunctional and / or polyfunctional polymerizable monomer>
In the curable resin composition of the present invention, a monofunctional and / or polyfunctional polymerizable monomer can be used in addition to the oligomer / polymer having the radical polymerizable group as long as the physical properties of the protective layer are not lowered. .

Examples of the monofunctional and / or polyfunctional polymerizable monomer include styrene, vinyltoluene, 4-t-butylstyrene, α-methylstyrene, 4-chlorostyrene, 4-methylstyrene, 4-chloromethylstyrene, Styrene monomers such as divinylbenzene; allyl ester monomers such as diallyl phthalate, diallyl isophthalate, triallyl cyanurate, triallyl isocyanurate; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl ( (Meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, Roxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxydiethylene glycol (meth) acrylate, butoxydiethylene glycol (meth) acrylate , Phenoxyethyl (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) Monofunctional (meth) acrylate compounds such as acrylate; ethylene glycol di (meth) acrylate, 1,6-hexanedioe Rudi (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 2-butyl-2-ethyl 1,3-propanediol di (meth) acrylate, dimethylol-tricyclodecane di (meth) acrylate, pentacyclopentadecane dimethanol di (meth) acrylate, di (meth) acrylic acid adduct of bisphenol A diglycidyl ether, Cyclohexanedimethanol di (meth) acrylate, norbornane dimethanol di (meth) acrylate, p-menthane-1,8-diol di (meth) acrylate, p-menthan-2,8-diol di (meth) acrylate, p-menthane- 3,8-gio Di (meth) acrylate, bicyclo [2.2.2] -octane-1-methyl-4-isopropyl-5,6-dimethylol di (meth) acrylate, hydroxypivalic acid neopentyl glycol ester di (meth) acrylate, bis ( Bifunctional (meth) acrylate compounds such as (meth) acryloxyneopentylglycol) adipate; trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tetra (meth) ), (Meth) acrylate derivatives such as tri- or more functional (meth) acrylate compounds such as acrylate, dipentaerythritol hexa (meth) acrylate, etc .; methoxyethyl (meth) acrylate, 2-methoxy-2-methyl Ethyl (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; triethylene glycol divinyl ether, cyclohexane dimethanol divinyl ether, hydroxybutyl vinyl ether, dodecyl vinyl ether, etc. Vinyl ether monomers: trimethylolpropane diallyl ether, pentaerythritol triallyl ether, allyl glycidyl ether, methylol melami Allyl ether monomers such as allyl ether of glycerol, adipic acid ester of glyceryl diallyl ether, allyl acetal, allyl ether of methylol glyoxalurein; maleic acid ester monomers such as diethyl maleate and dibutyl maleate; dibutyl fumarate, fumarate Fumaric acid ester monomers such as dioctyl acid; 4- (meth) acryloyloxymethyl-2-methyl-2-ethyl-1,3-dioxolane, 4- (meth) acryloyloxymethyl-2-methyl-2-isobutyl- 1,3-dioxolane, 4- (meth) acryloyloxymethyl-2-cyclohexyl-1,3-dioxolane, 4- (meth) acryloyloxymethyl-2,2-dimethyl-1,3-dioxolane, 3-Dioxolane monomer ; (Meth) acrylamide, N-vinylformamide, N, N-dimethyl (meth) acrylamide, N- (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl ( (Meth) acrylamide, N-propoxymethyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, methylenebis (meth) acrylamide, hydroxyethyl (meth) acrylamide, N-vinylpyrrolidone, And amide compounds such as N-vinylcaprolactam, N-vinylformamide, (meth) acryloylmorpholine, and the like. These polymerizable monomers may be used alone or in combination of two or more.

Further, from the viewpoint of good adhesion to a commonly used polycarbonate substrate, a heteropolymeric monomer can be preferably used. Among them, 2-vinyloxyethyl (meth) acrylate, 3-vinyloxyethyl (meth) acrylate, ( 2-vinyloxypropyl (meth) acrylate, 1-methyl-2-vinyloxyethyl (meth) acrylate, 4-vinyloxybutyl (meth) acrylate, 6-vinyloxyhexyl (meth) acrylate, 4- (meth) acrylic acid 4- Vinyloxycyclohexyl and 4-vinyloxymethylcyclohexylmethyl (meth) acrylate can be preferably used.

Among these polymerizable monomers, bifunctional or higher-functional (meth) acrylic ester compounds, (meth) acrylic ester compounds having an alicyclic structure substituent, and (meth) acrylic derivatives having an ether structure have good curability. The use of these materials is preferable because, for example, the protective layer has high transparency and hardness, and is excellent in long-term storage stability of the optical disk (change in warpage during heating acceleration test, remaining film property).

When a polymerizable monomer is used, the blending amount thereof is preferably 0% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, and preferably 70% by mass or less in the curable resin composition. More preferably, it is 60 mass% or less, More preferably, it is 50 mass% or less. When the blending amount of the polymerizable monomer exceeds 70% by mass, the curing shrinkage rate and the internal strain increase, and for example, the warp of the optical disk may increase or the protective layer may be cracked or cracked.

<Photopolymerization initiator>
The curable resin composition of the present invention contains a photopolymerization initiator as an essential component. By including the photopolymerization initiator, there is an effect that it can be quickly cured by light irradiation.

Examples of the radical photopolymerization 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 methylpropionyl) 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 And the like. These radical photopolymerization initiators may be used alone or in combination of two or more. Of these photoradical polymerization initiators, acetophenones are preferred, and 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-methyl Propan-1-one is preferred. Among them, oligo {2-hydroxy-2-methyl-1- is selected for the purpose of improving the durability of an optical disk using a curable resin composition for an optical disk as a protective layer and suppressing an increase in warpage during a heat resistance test. [4- (1-Methylvinyl) phenyl] propanone} is particularly preferred.

The blending amount of the photopolymerization initiator is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 8% by mass or less, and further preferably 1% by mass or more and 5% by mass in the curable resin composition. % Or less. A composition may not fully harden | cure that the compounding quantity of a photoinitiator is less than 0.1 mass%. On the other hand, when the blending amount of the photopolymerization initiator exceeds 10% by mass, the generation of odor and coloring of the cured product increase, the recyclability of the composition decreases, and the long-term storage stability of the optical disk deteriorates. There is a case.

The curable resin composition of the present invention may contain a thermal polymerization initiator as a polymerization initiator.

As the thermal polymerization initiator, a thermal radical polymerization initiator that generates a polymerization initiation radical by heating is suitable. When the thermal polymerization initiator is included, the heat generated when the composition is cured with ultraviolet rays is utilized, and the effect of further curing can be achieved.

Examples of the thermal radical polymerization initiator include methyl ethyl ketone peroxide, cyclohexanone peroxide, 1,1-bis (t-hexylperoxy) -cyclohexane, cumene hydroperoxide, bis (4-t-butylcyclohexyl) peroxydicarbonate, cumylperoxy Neodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexanoate, t-butylperoxy-2- Organic peroxide initiators such as ethylhexanoate and t-butylperoxybenzoate; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2 , 2'-azobis (2,4-dimethyl-4- Toxivaleronitrile), 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-methylpropionamidine]] dihydrochloride, 4,4 ′ -Azo initiators such as azobis (4-cyanopentanoic acid); These thermal radical initiators may be used alone or in combination of two or more. Among these thermal radical initiators, radicals can be efficiently generated by the catalytic action of metal soaps such as methyl ethyl ketone peroxide, cyclohexanone peroxide, cumene hydroperoxide, t-butylperoxybenzoate, benzoyl peroxide and / or amine compounds. Preferred compounds are 2,2′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile).

The blending amount of the polymerization initiator is preferably 0.05% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 15% by mass or less, and further preferably 0.2% by mass in the curable resin composition. It is 10 mass% or less. When the blending amount of the polymerization initiator is less than 0.05% by mass, the curable resin composition may not be sufficiently cured. On the contrary, when the amount of the polymerization initiator exceeds 20% by mass, the generation of odor and coloring of the cured product increase, or the long-term storage stability of the laminate obtained by applying to a plastic substrate and curing, for example. (Changes in warp during heating acceleration test, residual film property) may deteriorate.

<Other ingredients>
In addition, the curable resin composition of the present invention may contain an ultraviolet absorber, a thermal polymerization accelerator, a photosensitizer, and a photopolymerization accelerator.

In the case of containing an ultraviolet absorber, there are effects that the recyclability of the composition can be improved, the curing speed can be adjusted, and the warp of the optical disk can be reduced. Examples of the UV absorber include benzotriazole UV absorbers, hydroxyphenyltriazine UV absorbers, benzophenone UV absorbers, salicylic acid UV absorbers, and inorganic oxide UV absorbers.

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., conventionally known ultraviolet absorbers can be mentioned. In addition, the ultraviolet absorber is 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole (trade name “TINUVIN (registered trademark) PS”, Ciba Specialty Chemicals Co., Ltd.), 2- {2-hydroxy-4- (1-octyloxycarbonylethoxy) phenyl} -4,6-bis (4-phenylphenyl) -1,3,5-triazine (trade name “TINUVIN”) 479 ”, manufactured by Ciba Specialty Chemicals), 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) Nenyl} propionic acid, 2-ethylhexyl-3- {3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl} propionic acid (trade name “TINUVIN 109”, Ciba Specialty Chemicals Co., Ltd.) is preferable.

The addition amount of the ultraviolet absorber is preferably 0.03% by mass or more and 0.4% by mass or less, more preferably 0.03% by mass or more and 0.3% by mass or less, and more preferably in the curable resin composition. Is 0.05 mass% or more and 0.2 mass% or less, Most preferably, it is 0.05 mass% or more and 0.1 mass% or less.

When using a thermal radical polymerization initiator, in order to lower the decomposition temperature of the thermal radical polymerization initiator, a thermal polymerization accelerator capable of effectively generating radicals by promoting the decomposition of the thermal polymerization initiator is used. be able to. 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 ammonium. Examples thereof include salts, thiourea compounds, and ketone compounds. These thermal polymerization accelerators may be used alone or in combination of two or more. Among these thermal polymerization accelerators, cobalt octylate, cobalt naphthenate, copper octylate, copper naphthenate, manganese octylate, manganese naphthenate, dimethylaniline, trietalamine, triethylbenzylammonium chloride, di (2-hydroxy) Ethyl) p-toluidine, ethylenethiourea, acetylacetone, methyl acetoacetate are preferred.

The blending amount of the thermal polymerization accelerator is preferably 0.001% by mass to 20% by mass, more preferably 0.001% by mass to 10% by mass, and still more preferably 0.01% by mass in the curable resin composition. % To 5% by mass, most preferably 0.05% to 3% by mass. When the blending amount of the thermal polymerization accelerator is within such a range, it is preferable from the viewpoints of curability of the composition, physical properties of the cured product, and economical efficiency.

In the curable resin composition of the present invention, photosensitization is capable of effectively generating radicals by transferring excitation energy from an excited state generated by photoexcitation to a photopolymerization initiator and promoting decomposition of the photopolymerization initiator. An agent can be used.

Examples of the photosensitizer include 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and the like. These photosensitizers may be used alone or in combination of two or more.

The blending amount of the photosensitizer is preferably 0.05 parts by mass or more and 20% by mass or less, more preferably 0.1 parts by mass or more and 15% by mass or less, and further preferably 0.2% by mass in the curable resin composition. Part or more and 10% by mass or less. If the compounding quantity of a photosensitizer is in such a range, it is preferable at the point of sclerosis | hardenability of a composition, the physical property of hardened | cured material, and economical efficiency.

In the composition of the present invention, a photopolymerization accelerator capable of promoting the decomposition of the photopolymerization initiator and generating radicals effectively can be used. Examples of the photopolymerization accelerator include triethanolamine, methyldiethanolamine, triisopropanolamine, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, and 4-dimethylaminobenzoic acid. Examples include -2-n-butoxyethyl, 2-dimethylaminoethyl benzoate, N, N-dimethylparatoluidine, 4,4′-dimethylaminobenzophenone, 4,4′-diethylaminobenzophenone, and the like. These photopolymerization accelerators may be used alone or in combination of two or more. Of these photopolymerization accelerators, triethanolamine, methyldiethanolamine, and triisopropanolamine are preferable.

The blending amount of the photopolymerization accelerator is preferably 0.05% by mass to 20% by mass or less, more preferably 0.1% by mass to 15% by mass, and further preferably 0.2% by mass in the curable resin composition. It is within the range of 10% by mass or less. When the blending amount of the photopolymerization accelerator is within such a range, it is preferable from the viewpoint of curability of the composition, physical properties of the cured product, and economic efficiency.

When blending a combination of a thermal polymerization initiator, a photopolymerization initiator, a thermal polymerization accelerator, a photosensitizer, a photopolymerization accelerator, etc., the total amount of the blending amount is the total amount in the curable resin composition. On the other hand, it is preferably in the range of 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, and further preferably 0.2 to 10% by mass. If the total amount of the combination amount such as the polymerization initiator is within such a range, the curability of the curable resin composition, the physical properties of the cured product obtained by curing the curable resin composition, and the economical point Is preferable.

The curable resin composition of the present invention may contain a surface function modifier as necessary. By adding the surface conditioner, the fingerprint removal resistance is improved. As the surface function modifier, a fluorine compound or a silicone compound is generally used. In the present invention, a polyether-modified fluorine compound, a polyether-modified fluorine compound having a reactive group (for example, (meth) acrylate), a non-reactive silicone, a reactive (for example (meth) acrylate) silicone, a high Either molecular silicone or macromonomer silicone can be used.

The curable resin composition of the present invention may contain fine particles made of a metal oxide. In the case of containing fine particles made of a metal oxide, the hardness of the coating film after curing is improved, and there is an effect that a coating having low reflectivity is obtained with less damage.

More preferably, the metal oxide constituting the fine particles contains at least one metal element selected from the group consisting of Si, Ti, Zr, Zn, Sn, In, La, and Y. The metal oxide constituting the fine particles may be a single oxide containing these elements or a complex oxide containing these elements. Specific examples of the metal oxide constituting the fine particles include, 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. Examples thereof include ₂ O ₃ , SiO ₂ —Zr ₂ O ₃ , SiO ₂ —Ti ₂ O ₃ , Al ₂ O ₃ —ZrO ₂ , and TiO ₂ —ZrO ₂ . The fine particles comprising these metal oxides may be used alone or in combination of two or more. Of these fine particles made of a metal oxide, SiO ₂ , TiO ₂ , ZrO ₂ , and ZnO ₂ are preferable.

The average particle size of the fine particles comprising metal oxide is preferably 1 nm to 300 nm, more preferably 1 nm to 50 nm. If the average particle diameter of the fine particles exceeds 300 nm, the transparency of the cured product may be impaired. In addition, the average particle diameter of fine particles 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 fine particles made of metal oxide is preferably 0% by mass to 80% by mass, more preferably 0% by mass to 50% by mass in the curable resin composition. If the amount of fine particles exceeds 80% by mass, the cured product may become brittle. *

The curable resin composition of the present invention further includes, as necessary, a low shrinkage agent (reactive oligomer or polymer, non-reactive oligomer or polymer), color pigment, plasticizer, chain transfer agent, polymerization. Inhibitor, near infrared absorber, light stabilizer, antioxidant, flame retardant, matting agent, dye, antifoaming agent, leveling agent, antistatic agent, dispersant, slip agent, surface modifier, shaking A change agent, a thixotropic agent, etc. can be added. The presence of these additives does not particularly affect the effects of the present invention. These additives may be used alone or in combination of two or more.

The compounding amount of the additive may be set as appropriate according to the type and purpose of use of the additive, the method of using the curable resin composition, and the like, and is not particularly limited. For example, the compounding amount of the low shrinkage agent, the color pigment, the plasticizer or the auxiliary change agent is preferably 1% by mass or more and 40% by mass or less, more preferably 5% by mass or more and 30% by mass or less in the curable resin composition. More preferably, it is in the range of 10 mass% or more and 25 mass% or less. Polymerization inhibitors, antioxidants, matting agents, dyes, antifoaming agents, leveling agents, antistatic agents, dispersants, slip agents, surface modifiers or auxiliary agents are added to the curable resin composition. Among these, the range is preferably 0.0001% by mass to 10% by mass, more preferably 0.001% by mass to 5% by mass, and still more preferably 0.01% by mass to 3% by mass.

The curable resin composition for an optical disk of the present invention has a radical polymerizable unsaturated group equivalent (g / eq) in the curable resin composition of A and an alkylene oxide adduct-containing polyfunctional in the curable resin composition. When the content (mass%) of (meth) acrylic acid esters and caprolactone adduct-containing polyfunctional (meth) acrylic acid esters is B, it is necessary to satisfy 6.6 ≦ A ÷ B ≦ 35. is there.

In the curable resin composition of the present invention, a crosslinked structure is formed by a radically polymerizable unsaturated group, and a soft component is formed by an alkylene oxide skeleton and / or a caprolactone component of an adduct-containing (meth) acrylic acid ester. be introduced. That is, the curable resin composition of the present invention is prepared by blending adduct-containing (meth) acrylic acid esters and adjusting the ratio of A and B (A ÷ B) within a predetermined range. The shrinkage of the cured product is reduced, the resilience of the cured product obtained by curing the curable resin composition of the present invention is improved, and the elastic modulus, loss tangent, and glass transition temperature can be adjusted.

In the present invention, the reason why A ÷ B is defined without defining the respective preferable ranges for A and B is that the curable resin composition of the present invention contains an adduct that can introduce a soft component. This is because the preferred range of the radical polymerizable unsaturated group equivalent (A) capable of forming a crosslinked structure varies depending on the content (B) of (meth) acrylic acid esters.

For example, when B is about 60% by mass, when A is about 500 g / eq, the obtained cured product does not become too soft and the amount of permanent deformation becomes extremely small. However, when B is about 10% by mass, even if A is about 500 g / eq, the obtained cured product becomes too hard and the amount of permanent deformation is remarkably increased. On the other hand, when B is about 20% by mass, when A is about 310 g / eq, the obtained cured product does not become too hard and the amount of permanent deformation becomes extremely small. However, when B is about 50% by mass, even if A is about 320 g / eq, the resulting cured product becomes too soft, and the amount of permanent deformation increases significantly.

As described above, the preferable range of A varies depending on the value of B. Therefore, in order to appropriately define the preferred embodiment of the present invention, the range of A ÷ B is defined. In the present invention, by setting A ÷ B in the range of 6.6 to 35, the elastic modulus, loss tangent, and glass transition temperature have practical properties, and there is very little resilience and warpage of the laminate. It has an outstanding effect on the protective layer of the optical disk. When A ÷ B is less than 6.6, the cross-linked structure is reduced, so that the balance between the elastic modulus and loss tangent is deteriorated, and the amount of permanent deformation is increased, that is, a depression is formed when the protective layer is pushed. It becomes easy. On the other hand, when A ÷ B exceeds 35, the cross-linked structure is large, the warpage of the laminate due to curing shrinkage is increased, the resilience at the time of deformation is deteriorated, and a dent is easily formed.

<Radically polymerizable unsaturated group equivalent>
The radical polymerizable unsaturated group equivalent (g / eq) will be described. The radical polymerizable unsaturated group equivalent is the amount of the curable resin composition material per mole of the radical polymerizable unsaturated group. Here, when calculating the radical polymerizable unsaturated group equivalent, the mass of the photopolymerization initiator is not considered. The radically polymerizable unsaturated group is an ethylenically unsaturated group having radical polymerizability.

In the present invention, the radical polymerizable unsaturated group equivalent in the curable resin composition is calculated from the reaction calorific value using an optical DSC (photo DSC) apparatus. The optical DSC apparatus is a thermal analysis apparatus having a structure in which the DSC apparatus includes a UV irradiation unit. A UV curable resin sample is placed in the optical DSC apparatus and irradiated with a UV lamp in the apparatus, thereby accompanying a curing reaction. The curing exotherm can be observed as a DSC curve. As a method for measuring the amount of heat generated by curing, the following method is preferred.

<Optical DSC measurement method>
About 5 mg of the curable resin composition is accurately weighed in an aluminum dish having a diameter of about 5 mm. Irradiation intensity of 5 mJ / cm using an ultraviolet irradiation device (Seiko Denshi Kogyo Co., Ltd., UV-1 (light source: 200 W mercury-xenon lamp, filter: 365 nm interference filter and 20% ND filter)) in a nitrogen gas atmosphere at 30 ° C. ^The amount of heat generated by the curable resin composition with a differential scanning calorimeter (DSC) (DSC6200, manufactured by Seiko Denshi Kogyo Co., Ltd.) while irradiating ² seconds of ultraviolet rays for 5 minutes (mJ / mg: 1 mg of resin composition (photopolymerization started) Measure the calorific value per cure) excluding the agent. The amount of heat generated by curing 2-ethylhexyl acrylate (molecular weight: 184) was measured and found to be 420 mJ / mg. Based on this, the amount of radical polymerizable unsaturated groups was calculated. For example, the calorific value of a curable resin composition measured was 250 mJ / mg. The amount of the radical polymerizable unsaturated group of the curable resin composition is (184 × 420 ÷ 250) = 309.

The radical polymerizable unsaturated group equivalent in the curable resin composition of the present invention is preferably 250 g / eq or more, more preferably 300 g / eq or more, further preferably 350 g / eq or more, and preferably 600 g / eq or less, More preferably, it is 550 g / eq or less, More preferably, it is 500 g / eq or less. If the radically polymerizable unsaturated group equivalent is within the above range, the hardness of the resulting cured product can be adjusted to a more appropriate range, and a protective layer having a smaller permanent deformation can be formed.

In the curable resin composition of the present invention, the light transmittance of each wavelength at a thickness of 100 μm of the composition is (X) 85.0% or more at 400 nm and (Y) 35.0% or more 85 at 380 nm. It is preferably within a range of 0.0% or less and (Z) within a range of 0.1% or more and 50.0% or less at 360 nm. By setting the light transmittance at each wavelength within the above range, the composition is excellent in recyclability, and the optical disc having a protective layer formed by curing the composition is excellent in transparency and corrosiveness of the reflective film. Thus, an optical disk having a small surface and excellent surface lubricity and long-term storage stability (low warpage and residual film properties during a heating acceleration test) can be obtained.

The light transmittance at a wavelength of 400 nm is preferably 85.0% or more, more preferably 88% or more, and most preferably 90% or more. If the light transmittance at a wavelength of 400 nm is less than 85.0%, the transparency may be inferior and accurate data recording and reproduction on the optical disc may not be possible.

The light transmittance at a wavelength of 380 nm is preferably 35.0% or more and 85.0% or less, more preferably 45.0% or more and 85.0% or less, and most preferably 45.0% or more and 75.0%. % Or less. When the light transmittance at a wavelength of 380 nm is out of the above range, when the composition is inferior in recyclability, the long-term storage stability of the optical disk (change in warpage during heating acceleration test, residual film property) is deteriorated, reflection When the corrosiveness of the film is lowered, the lubricity of the surface may be lowered.

The light transmittance at a wavelength of 360 nm is preferably 0.1% to 50.0%, more preferably 0.5% to 50.0%, and most preferably 5% to 30.0%. When the light transmittance at a wavelength of 360 nm is outside the above range, when the composition is inferior in recyclability, the long-term storage stability of the optical disk (change in warpage during heating acceleration test, residual film property) is deteriorated, reflection When the corrosiveness of the film is lowered, the lubricity of the surface may be lowered.

The light transmittance is a value obtained by injecting the curable resin composition into a quartz glass cell through a 100 μm spacer and measuring the light transmittance at each wavelength using a spectrophotometer. In that case, air is adopted as a blank.

The viscosity of the curable resin composition of the present invention is preferably 800 mPa · s or more, more preferably 1000 mPa · s or more, preferably 3500 mPa · s or less, more preferably 2500 mPa · s or less at 25 ° C. Here, the viscosity is a value calculated using a B-type viscometer (model “RB80L”: manufactured by Toki Sangyo Co., Ltd.) under the condition of a temperature of 25 ° C. If the viscosity is out of the range of 800 mPa · s to 3500 mPa · s, the thickness of the protective layer may not be controlled to 100 μm ± 2 μm. Specifically, when the thickness of the protective layer in the center becomes thinner, In some cases, the thickness of the protective layer of the portion increases.

<Production method of composition and curing method thereof>
The curable resin composition of the present invention includes the above-mentioned alkylene oxide adduct-containing polyfunctional (meth) acrylic acid esters and / or caprolactone adduct-containing polyfunctional (meth) acrylic acid esters, photopolymerization initiators, and the like. It can be obtained by mixing and stirring by the above method.

The curable resin composition of the present invention can be cured by irradiation with ultraviolet rays. Curing here refers to a state without fluidity. The wavelength of the ultraviolet rays used may be in the range of 150 nm to 450 nm. Examples of the light source that emits such a wavelength include sunlight, low-pressure mercury lamp, high-pressure mercury lamp, ultra-high pressure mercury lamp, metal halide lamp, gallium lamp, xenon lamp, flash type xenon lamp, and carbon arc lamp. Irradiation integrated light quantity is preferably 0.1 J / cm ² or more 3J / cm ² or less, more preferably 0.2 J / cm ² or more 2.0 J / cm ² or less, more preferably 0.3 J / cm ² or more 1. Within the range of 0 J / cm ² or less.

Together with these light sources, it is possible to use heat by infrared rays, far infrared rays, hot air, high frequency heating or the like. The heating temperature may be appropriately adjusted according to the type of the base material and the like, and is not particularly limited. It is in the range of not lower than 170 ° C and lower than 170 ° C. 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 or more. Within 6 hours or less.

When curing by irradiation with an electron beam as well as curing by light irradiation, an electron beam having an acceleration voltage of preferably 10 kV to 500 kV, more preferably 20 kV to 300 kV, and even more preferably 30 kV to 200 kV is used. That's fine. Further, the irradiation amount of the electron beam is preferably 2 kGy or more and 500 kGy or less, more preferably 3 kGy or more and 300 kGy or less, and further preferably 4 kGy or more and 200 kGy or less.

As a coating method in the case of obtaining an optical disk by applying the curable resin composition of the present invention to a substrate and curing it, conventionally known methods such as various printing methods such as gravure printing, bar coater method, spin coater method are used. You may select according to.

<Hardened product>
The cured product obtained by curing the curable resin composition of the present invention preferably has a light transmittance at 405 nm at a thickness of 100 μm of 85% or more, more preferably 88% or more, and still more preferably 89%. That's it. The light transmittance is a value measured by a spectrophotometer using the obtained cured product. A cured product obtained by curing the curable resin composition of the present invention is a (meth) acrylic acid ester, a photopolymerization initiator, an oligomer having at least one radical polymerizable group and / or an ion polymerizable group. And the said light transmittance can be achieved by containing a polymer and a polymerizable monomer suitably and performing sufficient hardening by predetermined hardening conditions and methods. When the light transmittance at 405 nm is less than 85%, the transparency is inferior, and thus when used as a protective layer of an optical disk, errors may increase when reading recorded information.

The cured product obtained by curing the curable resin composition of the present invention has a weight loss when it is kept in an oven at 70 ° C. for 100 hours (hereinafter sometimes simply referred to as “mass reduction”). It is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, preferably 2.0% by mass or less, more preferably 1.5% by mass or less, and most preferably 1.0% by mass or less. is there. The thickness of the cured product to be measured is 100 μ ± 2 μm.

The cause of the mass decrease is considered to be an unreacted (meth) acrylic acid ester component, a residue of the initiator and its decomposition product, or a low molecular weight additive. Mass reduction includes oligomers and / or polymers having radically polymerizable groups, (meth) acrylic acid esters, and photopolymerization initiators, and is sufficiently cured by predetermined curing conditions and methods to be within the above range. It becomes possible to do.

In order to reduce the mass to less than 0.1% by mass, a drying (decompression) step of the cured product is required, which increases the cost. On the other hand, if the mass decrease exceeds 2.0% by mass, the surface of the cured product of volatile components There are cases where errors increase during reading of recorded information due to bleed-out of the recording medium and changes in the thickness of the protective layer, and the long-term storage stability of the optical disk is deteriorated. That is, by reducing the weight loss to 0.1% by mass or more and 2.0% by mass or less, for example, in an optical disc, not only the surface accuracy with time is reduced but storage stability is improved, but also in an automobile or the like. It can be used and stored.

When the cured product obtained by curing the curable resin composition of the present invention preferably has a low elastic modulus, the storage elastic modulus E ′ at 25 ° C. is 10 MPa or more, preferably 20 MPa or more. 150 MPa or less, more preferably 120 MPa or less, still more preferably 100 MPa or less. The storage elastic modulus E ′ is a value obtained by dynamic viscoelasticity measurement using the obtained cured product. Measurement conditions will be described later. A cured product having a storage elastic modulus E ′ of 10 MPa or more and 150 MPa or less can be obtained by sufficiently curing the curable resin composition under a predetermined curing condition or curing method. If the storage elastic modulus E ′ is less than 10 MPa, the long-term storage stability of the optical disk may be deteriorated. In particular, the optical disk is sometimes recessed. Moreover, when the storage elastic modulus is larger than 150 MPa, the warp of the obtained optical disk may increase or the long-term storage stability may deteriorate.

When the cured product obtained by curing the curable resin composition of the present invention preferably has a low elastic modulus, the loss tangent tan δ at 25 ° C. is preferably 0.10 or more, and 0.70 or less. More preferably, it is 0.60 or less, More preferably, it is 0.50 or less, Most preferably, it is 0.40 or less. The loss tangent tan δ is a value obtained by dynamic viscoelasticity measurement as with the storage elastic modulus E ′. Note that the same measurement conditions are used. When the loss tangent tan δ exceeds 0.70, the long-term storage stability of the optical disk may be deteriorated. In particular, the optical disk is sometimes recessed. Further, when the loss tangent tan δ is less than 0.10, the warp of the obtained optical disk may increase or the long-term storage stability may deteriorate.

When the cured product obtained by curing the curable resin composition of the present invention preferably has a low elastic modulus, the glass point transition temperature is preferably 0 ° C. or higher, more preferably 5 ° C. or higher. More preferably, it is 10 degreeC or more, and 30 degrees C or less is preferable. The glass point transition temperature is a value obtained by dynamic viscoelasticity measurement in the same manner as the storage elastic modulus E ′, and the temperature of the maximum tan δ value is adopted. The measurement conditions are the same as the storage elastic modulus E ′. When the glass point transition temperature exceeds 30 ° C., the warp of the optical disk may increase. In addition, when the glass point transfer temperature is less than 0 ° C., the optical disk may be recessed, and the long-term storage stability may be deteriorated.

When the cured product obtained by curing the curable resin composition of the present invention preferably has a high elastic modulus, the storage elastic modulus E ′ at 25 ° C. is preferably 1200 MPa or more, more preferably 1400 MPa. As described above, more preferably 1600 MPa or more, most preferably 1800 MPa or more, and preferably 2100 MPa or less. The storage elastic modulus E ′ is a value obtained by dynamic viscoelasticity measurement using a cured product obtained in the same manner as described above. By sufficiently curing the curable resin composition under predetermined curing conditions and curing methods, a cured product having a storage elastic modulus E ′ of 1200 MPa to 2100 MPa could be obtained. When the storage elastic modulus E ′ is smaller than 1200 MPa, the long-term storage stability of the optical disk may be deteriorated. In particular, there are dents.

When the cured product obtained by curing the curable resin composition of the present invention preferably has a high elastic modulus, the loss tangent tan δ at 25 ° C. is preferably 0.03 or more, and 0.12 or less. Is preferable, more preferably 0.10 or less, and still more preferably 0.07 or less. The loss tangent tan δ is a value obtained by dynamic viscoelasticity measurement as with the storage elastic modulus E ′. Note that the same measurement conditions are used. If the loss tangent tan δ exceeds 0.12, the long-term storage stability of the optical disk may deteriorate. In particular, the optical disk is sometimes recessed.

When the cured product obtained by curing the curable resin composition of the present invention preferably has a high elastic modulus, the glass point transfer temperature is preferably 60 ° C. or higher, more preferably 70 ° C. or higher. More preferably, it is 75 degreeC or more, Most preferably, it is 80 degreeC or more, 90 degreeC or less is preferable, More preferably, it is 85 degreeC or less. The glass point transition temperature is a value obtained by dynamic viscoelasticity measurement in the same manner as the storage elastic modulus E ′, and the temperature of the maximum tan δ value is adopted. The measurement conditions are the same as the storage elastic modulus E ′. If the glass point transition temperature is less than 60 ° C., the optical disk may be dented or the long-term storage stability may be deteriorated.

The curable resin composition of the present invention is suitably used for optical disks. The cured product obtained by curing the curable resin composition of the present invention is particularly excellent in scratch resistance and hardness, and further, since the warpage of the substrate is small over a long period of time, it is a blue-violet laser as a laser beam for information reading and writing, in particular. It can be suitably used for an optical disc using light (Blu-ray Disc (registered trademark)).

≪Optical disc≫
The optical disk of the present invention has a protective layer formed by curing the above-described curable resin composition for an optical disk of the present invention.

The optical disk of the present invention can be obtained by forming a protective layer formed by curing the curable resin composition for an optical disk of the present invention on a reflective film formed on a substrate. Of the optical disk manufacturing methods in the present invention, a conventionally known optical disk manufacturing method is used except for the protective layer manufacturing method.

The protective layer obtained by curing the curable resin composition of the present invention preferably has a thickness of 20 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more, particularly preferably 70 μm or more, and most preferably 80 μm or more. Have. The protective layer preferably has a thickness of 150 μm or less, more preferably 120 μm or less, and still more preferably 105 μm or less. When used for an optical disk, if the thickness of the protective layer is less than 20 μm, the protection of the functional layer such as the recording layer and the reflective layer in the protective layer may be insufficient, and if the thickness exceeds 150 μm, the thickness and the like can be controlled. It can be difficult.

Examples of the substrate used for the optical disc include resin molded products such as polymethyl methacrylate (PMMA), polystyrene (PS), polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene copolymer (ABS), and polycarbonate (PC). And film; Glass etc. are mentioned. Among these, polycarbonate (PC) is preferable.

In the present invention, the term “on the reflective film” means not only a mode in which a protective layer is directly laminated on the reflective film, but also a functional layer such as a recording layer or a dielectric layer is laminated on the reflective film, and the protective layer is protected on the functional layer. The form by which a layer is laminated | stacked is also meant. In addition, in order to increase the recording capacity of the optical disc, an optical disc having a multilayer structure with two or more information recording layers is manufactured. Between these information recording layers, an intermediate layer is formed by curing a transparent ultraviolet curable resin with ultraviolet rays. The composition of the present invention is suitable for forming a protective layer of an optical disk, but may be used as an ultraviolet curable resin for this intermediate layer.

Examples of the optical disc of the present invention include a Blu-ray disc (registered trademark). Since the optical disk of the present invention is excellent in transparency, it can be suitably used for an optical disk for recording / reproduction using, for example, an oscillator of 380 nm to 430 nm. Protective layer for Blu-ray Disc (registered trademark) has low warpage (low shrinkage), transparency (light transmission), adhesion to polycarbonate substrate, low corrosivity, recyclability, fast curing (productivity) , Characteristics such as dimensional stability (change in warpage during accelerated test, residual film property, small amount of permanent deformation such as dents) are required, but the curable resin composition for optical disc of the present invention is cured. This protective layer satisfies all the above characteristics. In addition, this invention is not limited to embodiment mentioned above, A various change is possible in the range shown to the claim.

It is also a preferable aspect that the optical disc of the present invention has a hard coat layer directly formed on the protective layer. Examples of the hard coat resin composition for forming the hard coat layer include (1) a hard coat containing a multi-branched reactive compound and / or a polymer having a reactive group in a side chain, and a polymerization initiator. Resin composition (hereinafter sometimes referred to as the first hard coat resin composition); (2) The number of repeating units per one valence to a polyhydric alcohol having a valence of 4 or more is n = 1, 2 The addition repeating unit per valence to the polyfunctional (meth) acrylic acid ester containing an alkylene oxide adduct obtained from a certain alkylene oxide adduct and / or a polyhydric alcohol having a valence of 4 or more is n = 1,2. Resin composition for hard coat containing a caprolactone adduct-containing polyfunctional (meth) acrylic acid ester obtained from a caprolactone adduct and a photopolymerization initiator Sometimes referred to as Dokoto resin composition);. Is suitable.

The first hard coat resin composition will be described.

As the multi-branched reactive compound, those exemplified as the compound having a radical polymerizable unsaturated group that can constitute the curable resin composition of the present invention can be used.

As the multi-branched reactive compound, a dendrimer represented by the above formula (3) and / or a hyperbranched polymer represented by the above formula (4) is preferable.

The polymer having a reactive group in the side chain has a repeating unit represented by the above formula (1) exemplified as an oligomer / polymer having a radical polymerizable group that can constitute the curable resin composition of the present invention. Vinyl polymers can be used.

Examples of the polymer having a reactive group in the side chain other than the vinyl polymer represented by the above formula (1) include, for example, a copolymer of methyl methacrylate and methacrylic acid described in JP-A No. 11-263893. A (meth) acrylic polymer having a plurality of polymerizable double bonds in the molecule obtained by esterifying an unsaturated epoxy compound glycidyl methacrylate can be mentioned.

The blending amount of the multi-branched reactive compound and / or the polymer having a reactive group in the side chain is preferably 10% by mass or more and less than 90% by mass in the first hard coat resin composition, more preferably 30%. It is not less than 70% by mass. If the blending amount of the multi-branched reactive compound and / or the polymer having a reactive group in the side chain is less than 10% by mass, the crosslinking density is lowered, so the curing speed is lowered and the coating strength of the cured product is insufficient. May be. Further, when the blending amount is 90% by mass or more, there is a case where the warpage of the laminate obtained by applying to the substrate and curing is increased.

The first hard coat resin composition contains a polymerization initiator as an essential component, but is a thermal polymerization initiator that generates a polymerization initiating radical by heating; photopolymerization that generates a polymerization initiating radical by irradiation with ultraviolet rays. And a photocationic polymerization initiator that generates a polymerization initiating cation upon irradiation with ultraviolet rays. These polymerization initiators may be used alone or in combination of two or more. It is also preferable to further add a thermal polymerization accelerator, a photosensitizer, a photopolymerization accelerator, and the like. As these polymerization initiator, thermal polymerization accelerator, photosensitizer, and photopolymerization accelerator, those exemplified as those that can constitute the curable resin composition of the present invention can be used. Moreover, the suitable range of these compounding quantities is the same as that of the curable resin composition of this invention.

The first hard coat resin composition contains an oligomer and / or polymer having a reactive group in addition to the multi-branched reactive compound, the polymer having a reactive group in the side chain, and the polymerization initiator. Also good. The reactive group in the oligomer and / or polymer is preferably a (meth) acryloyl group. As the oligomer or polymer having a (meth) acryloyl group, urethane (meth) acrylate, (meth) acryloyl group pendant polymer, epoxy resin, vinyl ether group pendant polymer, epoxy (meth) acrylate, and polyester (meth) acrylate are preferable.

In the first hard coat resin composition, the amount of the oligomer and / or polymer having the (meth) acryloyl group in the hard coat resin composition is preferably 20% by mass to 80% by mass, and more preferably. Is 30 mass% or more and 70 mass% or less. When the blending amount of the oligomer and / or polymer having the (meth) acryloyl group exceeds 80% by mass, the content of the multi-branched reactive compound decreases, and thus warpage after application to the substrate increases. In some cases, the toughness is lowered and the coating film is cracked and peeled off, or the long-term storage stability is deteriorated.

Also, the first hard coat resin composition may contain a polymerizable monomer such as a (meth) acrylic monofunctional monomer or a (meth) acrylic polyfunctional monomer. The polymerizable monomer is not particularly limited as long as it can be co-cured with the multi-branched reactive compound. Specifically, for example, it may constitute the curable resin composition of the present invention. What was illustrated as a monofunctional and / or polyfunctional polymerizable monomer can be used.

In the first hard coat resin composition, the amount of the polymerizable monomer is preferably 0% by mass to 80% by mass, more preferably 10% by mass to 60% by mass in the hard coat resin composition. It is. When the compounding amount of the polymerizable monomer exceeds 80% by mass, the curing shrinkage rate and the internal strain increase, and for example, the warpage of the laminate obtained by applying to a plastic substrate and curing may increase.

Next, the second hard coat resin composition will be described.

An alkylene oxide adduct-containing polyfunctional (meth) acrylic acid ester obtained from an alkylene oxide adduct wherein n = 1 or 2 is added to the tetravalent or higher polyhydric alcohol per monovalent repeating unit and / or Caprolactone adduct-containing polyfunctional (meth) acrylic acid esters obtained from a caprolactone adduct having an addition repeating unit per valence to a polyhydric alcohol of 4 or more are n = 1 or 2 are, for example, penta Multivalent polyhydric alcohols such as erythritol, dipentaerythritol, ditrimethylolpropane, sorbitol, mannitol, etc. added with alkylene oxide and / or caprolactone with additional repeating units n = 1 or 2 per hydroxyl group. Multifunctional (meth) active compounds obtained using alcohol adducts A Le esters.

As the alkylene oxide adduct-containing polyfunctional (meth) acrylic acid ester obtained from an alkylene oxide adduct in which the addition repeating unit per valence to the polyhydric alcohol of 4 or more is n = 1 or 2, For example, tetra (meth) acrylate of ethylene oxide 4 mol adduct of pentaerythritol, tetra (meth) acrylate of ethylene oxide 8 mol adduct of pentaerythritol, tetra (meth) acrylate of propylene oxide 4 mol adduct of pentaerythritol, Tetra (meth) acrylate of propylene oxide 8 mol adduct of pentaerythritol, hexa (meth) acrylate of ethylene oxide 6 mol adduct of dipentaerythritol, ethylene oxide 12 mol of dipentaerythritol Adduct hexa (meth) acrylate, dipentaerythritol propylene oxide 6 mol adduct hexa (meth) acrylate, dipentaerythritol propylene oxide 12 mol adduct hexa (meth) acrylate, dipentaerythritol ethylene oxide 5 Mole adduct penta (meth) acrylate, dipentaerythritol ethylene oxide 10 mol adduct penta (meth) acrylate, ditrimethylolpropane ethylene oxide 6 mol adduct hexa (meth) acrylate, ditrimethylolpropane ethylene oxide 12 mol adduct hexa (meth) acrylate, ditrimethylolpropane propylene oxide 6 mol adduct hexa (meth) acrylate, ditrimethylolprop Hexa (meth) acrylate of propylene oxide 12 mol adduct of hexa (meth) acrylate of sorbitol ethylene oxide 6 moles adduct, etc. hexa (meth) acrylate of ethylene oxide 6 moles adduct of mannitol.

Examples of the caprolactone adduct-containing polyfunctional (meth) acrylic acid ester obtained from a caprolactone adduct having n = 1 or 2 per 1 valence addition unit to the polyhydric alcohol having 4 or more valences include: Tetra (meth) acrylate of pentaerythritol ε-caprolactone 4 mol adduct, tetra (meth) acrylate of ε-caprolactone 8 mol adduct of pentaerythritol, hexa (meth) of ε-caprolactone 6 mol adduct of dipentaerythritol Hexa (meth) acrylate of acrylate, dipentaerythritol ε-caprolactone 12 mol adduct, penta (meth) acrylate of dipentaerythritol ε-caprolactone 5 mol adduct, dipentaerythritol ε-caprolactone 10 mol adduct pen Hexa (meth) acrylate of ε-caprolactone 6 mol adduct of (meth) acrylate, ditrimethylolpropane, hexa (meth) acrylate of ε-caprolactone 12 mol adduct of ditrimethylolpropane, ε-caprolactone 6 mol adduct of sorbitol And hexa (meth) acrylate of a 6-mol adduct of ε-caprolactone with mannitol.

An alkylene oxide adduct-containing product obtained from an alkylene oxide adduct having n = 1,2 per 1 valence addition unit to the polyhydric alcohol of 4 or more valence in the second hard coat resin composition Caprolactone adduct-containing polyfunctional (meta) obtained from a caprolactone adduct having n = 1,2 per unit valence to a functional (meth) acrylic acid ester and / or a polyhydric alcohol having a valence of 4 or more. ) The total amount of acrylic acid esters is preferably 30% by mass or more, more preferably 40% by mass or more, preferably 80% by mass or less, and more preferably 70% by mass or less. If the total amount exceeds 80% by mass, warpage after application to the laminate of the substrate / protective layer may increase. On the other hand, if the total amount is less than 30% by mass, the scratch resistance and hardness decrease. Hard coat performance may not be exhibited.

The second hard coat resin composition contains a photopolymerization initiator as an essential component. Examples of the photopolymerization initiator include a photopolymerization initiator that generates a polymerization initiation radical upon irradiation with ultraviolet rays, and a photocationic polymerization initiator that generates a polymerization initiation cation upon irradiation with ultraviolet rays. These polymerization initiators may be used alone or in combination of two or more. It is also preferable to further add a thermal polymerization accelerator, a photosensitizer, a photopolymerization accelerator, and the like. As these polymerization initiator, thermal polymerization accelerator, photosensitizer, and photopolymerization accelerator, those exemplified as those that can constitute the curable resin composition of the present invention can be used. The blending amount of the photopolymerization initiator is preferably 0.5% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and still more preferably based on the total amount of the second hard coat resin composition. 2% by mass to 10% by mass. When the blending amount of the photopolymerization initiator is less than 0.5% by mass, the composition may not be cured sufficiently. On the other hand, if the blending amount of the photopolymerization initiator exceeds 20% by mass, the physical properties of the cured product will not be further improved, but rather adversely affected and the economy may be impaired.

The second hard coat resin composition preferably contains vinyl ether group-containing (meth) acrylic acid esters. Vinyl ether group-containing (meth) acrylic acid esters have good adhesion to the polycarbonate usually used as a substrate and an effect of reducing the viscosity of the hard coat material with a high dilution effect. Examples of the vinyl ether group-containing (meth) acrylic acid esters include 2-vinyloxyethyl (meth) acrylate, 3-vinyloxyethyl (meth) acrylate, 2-vinyloxypropyl (meth) acrylate, and (meth) acrylic acid 1 -Methyl-2-vinyloxyethyl, 4-vinyloxybutyl (meth) acrylate, 6-vinyloxyhexyl (meth) acrylate, 4-vinyloxycyclohexyl (meth) acrylate, 4-vinyloxymethylcyclohexyl methyl (meth) acrylate , 2- (2-vinyloxyethoxy) ethyl (meth) acrylate, 2- (2-vinyloxyisopropoxy) propyl (meth) acrylate, 2- {2- (2-vinyloxyethoxy) (meth) acrylate ) Ethoxy} ethyl. Of these, 2- (2-vinyloxyethoxy) ethyl (meth) acrylate is preferred. The blending amount of the vinyl ether group-containing (meth) acrylic acid ester in the second hard coat resin composition is preferably 5% by mass to 35% by mass, more preferably 10% by mass to 30% by mass.

The second hard coat resin composition is preferably 20 mPa · s or more and 100 mPa · s or less at 25 ° C. More preferably, it is 30 mPa * s or more and 80 mPa * s, More preferably, it is 40 mPa * s or more and 70 mPa * s. If the viscosity of the resin composition for hard coat is within the above range, the hard coat layer can be formed with a uniform thickness. However, if the viscosity of the hard coat resin composition is out of the above range, the thickness of the center portion of the hard coat layer may be reduced or the thickness of the end portion may be increased. Here, the viscosity is a value calculated using a B-type viscometer (model “RB80L” manufactured by Toki Sangyo Co., Ltd.) under the condition of a temperature of 25 ° C.

The second hard coat resin composition may contain an oligomer and / or polymer having a reactive group. The reactive group in the oligomer and / or polymer is preferably a (meth) acryloyl group. As the oligomer or polymer having a (meth) acryloyl group, urethane (meth) acrylate, (meth) acryloyl group pendant polymer, epoxy resin, vinyl ether group pendant polymer, epoxy (meth) acrylate, and polyester (meth) acrylate are preferable. In the second hard coat resin composition, the amount of the oligomer and / or polymer having a (meth) acryloyl group is preferably 3% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 15% by mass or less. is there. If the blending amount of the oligomer and / or polymer exceeds 20% by mass, the viscosity may increase and an appropriate hard coat layer thickness may not be formed. Moreover, if it is less than 3 mass%, the curvature after apply | coating to a board | substrate may become large, a toughness may fall, a coating-film crack, peeling, etc. may arise, or long-term storage stability may worsen. .

The second hard coat resin composition may contain a polymerizable monomer such as a (meth) acrylic monofunctional monomer or a (meth) acrylic polyfunctional monomer. As these polymerizable monomers, for example, those exemplified as monofunctional and / or polyfunctional polymerizable monomers that can constitute the curable resin composition of the present invention can be used. In the second hard coat resin composition, the compounding amount of the polymerizable monomer is preferably more than 0% by mass and less than 60% by mass, and more preferably 10% by mass to 50% by mass with respect to the total amount of the composition. It is. When the blending amount of the polymerizable monomer exceeds 60% by mass, the curing shrinkage rate and the internal strain increase, and for example, the warpage after coating and curing on the substrate / protective layer laminate may increase.

The cured product obtained by curing the second hard coat resin composition preferably has a storage elastic modulus E ′ at 25 ° C. of 600 MPa to 2000 MPa, more preferably 700 MPa to 1800 MPa, most preferably 700 MPa to 1600 MPa. It is as follows. When the storage elastic modulus E ′ exceeds 2000 MPa, the toughness is lowered and cracks may occur when the hard coat layer is deformed. Further, if the storage elastic modulus E ′ is less than 600 MPa, the intended hardness may not be obtained. The storage elastic modulus E ′ is a value obtained by dynamic viscoelasticity measurement using the obtained cured product. The glass transition temperature of the cured product of the second hard coat resin composition is not particularly limited, but the glass point transition temperature is preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 45 ° C. The temperature is 90 ° C. or lower, and most preferably 50 ° C. or higher and 80 ° C. or lower. The glass point transition temperature is a value obtained by dynamic viscoelasticity measurement in the same manner as the storage elastic modulus E ′, and the temperature of the maximum tan δ value is adopted. The measurement conditions of the dynamic viscoelasticity measurement are as follows: sample size width 8 mm × length 50 mm × thickness 100 μm, tension mode, frequency 1 Hz, clamp distance 25 mm, amplitude 0.1%, temperature increase rate 5 ° C./min. It is preferable to adopt.

The first and second hard coat resin compositions may further contain, as necessary, non-reactive resins (for example, acrylic resins, urethane acrylate resins, polyester resins, polyurethane resins, polystyrene resins, Vinyl chloride resin, etc.), color pigments, plasticizers, chain transfer agents, polymerization inhibitors, ultraviolet absorbers, near infrared absorbers, light stabilizers, antioxidants, flame retardants, matting agents, dyes, antifoaming An agent, a leveling agent, an antistatic agent, a dispersant, a slip agent, a surface modifier, a thixotropic agent, a thixotropic agent, fine particles comprising a metal oxide, and the like can be added. The presence of these additives does not particularly affect the effects of the present invention. These additives may be used alone or in combination of two or more. Moreover, the suitable range of the compounding quantity of these additives is the same as that of the curable resin composition of the present invention.

The first and second hard coat resin compositions are obtained by mixing and stirring the multi-branched reactive compound, a polymer having a reactive group in the side chain, a polymerization initiator, and the like by a known method. Can do. In addition, as for the coating method and the curing method when forming the hard coat layer using the hard coat resin composition, the same method as the coating method and curing method in the curable resin composition of the present invention should be adopted. That's fine.

The optical disk of the present invention has an antistatic layer, an adhesive layer, an adhesive layer, an easy-adhesion layer, a strain relaxation layer, an antiglare layer (non-glare) layer, a photocatalyst layer, etc. Various functional layers such as a layer, an ultraviolet shielding layer, a heat ray shielding layer, an electromagnetic wave shielding layer, a gas barrier layer, a reflective layer, a recording layer, and a dielectric layer may be laminated and applied. In addition, the lamination order of the protective layer obtained by curing the curable resin composition of the present invention and each functional layer is not particularly limited, and the lamination method is not particularly limited.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited by the following examples and comparative examples, and is suitable within a range that can meet the purpose described above and below. It is also possible to carry out with modification, and they are all included in the technical scope of the present invention.

≪Evaluation method≫
<Viscosity>
Values obtained by measuring the obtained curable resin composition using a B-type viscometer (model “RB80L” manufactured by Toki Sangyo Co., Ltd.) under a temperature of 25 ° C. were used.

<Transparency of cured layer>
Only the cured layer (cured film of the composition) was peeled off from the obtained substrate / cured layer laminate with a predetermined size, and the light transmittance at 405 nm was measured with a spectrophotometer (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.
A: The transmittance is 89% or more. B: The transmittance is 85% or more. X: The transmittance is less than 85%.

<Weight loss>
Only the protective layer (cured film of the composition) is peeled off from the obtained substrate / protective layer laminate at a predetermined size, and the weight loss (%) before and after the heating acceleration test (held in an oven at 70 ° C. for 100 hours) 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: Weight loss is 1.0 mass% or less. O: Mass loss is 2.0 mass% or less. X: Mass loss exceeds 2.0 mass%.

<Residual film properties>
Measure the thickness of the cured layer before and after the heating acceleration test (the total of the protective layer and hard coat layer if a hard coat layer is formed) using a laser focus displacement meter, and the remaining film rate (%) Was calculated by the following general formula, and the remaining film property was evaluated according to the following criteria.
Residual film ratio (%) = thickness of cured layer after heating acceleration test / thickness of cured layer before heating acceleration test × 100
○: Remaining film ratio is 97.0% to less than 103% ×: Remaining film ratio is less than 97.0% or 103% or more.

<Initial warpage increase>
The obtained substrate / cured layer laminate was placed on a horizontal glass plate so that the cured layer (cured film of the composition) was on the upper surface side, and then the warp of the laser displacement reading method manufactured by Nippon Shokubai Co., Ltd. Using an angle measuring device, the radial tilt value at a radius of 58 mm was measured in an environment of a temperature of 25 ° C. and a relative humidity of 50%. As the initial warpage increase amount, the warpage change amount before and after coating was adopted.

<War increase after heating acceleration test>
The obtained substrate / cured layer laminate was kept in an oven at 70 ° C. for 100 hours, and the warpage value when the substrate was left in an environment of 25 ° C. and 50% relative humidity for 24 hours increased the initial warpage. The radial tilt value was measured in the same manner as the amount. Thereby, the amount of warpage increase before and after the heating acceleration test was obtained.

<Storage elastic modulus E 'at 25 ° C>
The cured layer (cured film of the cured product) was peeled from the obtained substrate / cured layer laminate, and measured using the TA Instruments dynamic viscoelasticity measuring device RSAIII under the following measurement conditions.
(1) Sample size: width 8mm, length 50mm
(2) Clamp distance 25mm
(3) Measurement mode: Pull (4) Frequency: 1 Hz
(5) Width: 0.1%
(6) Temperature rising rate: 5 ° C./minute Dynamic viscoelasticity was measured, and the obtained value of the storage elastic modulus E ′ at 25 ° C. was adopted.

<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.

<Glass point transfer temperature Tg>
It 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.

<Permanent deformation amount>
Using the obtained substrate / cured layer laminate, using a micro-compression tester (manufactured by Shimadzu Corporation, model MCT-W500), the test conditions were as follows: flat indenter used 50 μm diameter, load speed 20 mN / second, maximum load 300 mN, A value obtained by measuring the amount of deformation remaining in the substrate / protective layer 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 this test, when the amount of permanent deformation exceeds 1 μm, reading errors due to laser light are likely to occur due to dents or the like, and the long-term storage stability may be poor.

<Light transmittance of the composition>
The light transmittance of the obtained composition at 400 nm, 380 nm, and 360 nm was measured using a spectrophotometer (model UV-3100, manufactured by Shimadzu Corporation). The light transmittance is a value obtained by injecting the composition into a quartz glass cell through a 100 μm spacer and measuring the transmittance at each wavelength using a spectrophotometer. Air was used as a blank.

<Recyclability of the composition>
After the initial viscosity of the obtained composition was measured by the above-described method, the composition that was not used for the protective layer (cured film of the composition) of the optical disc (the composition that protruded from the substrate during spin coating) was recovered. The viscosity was measured. Using the obtained initial viscosity and the recovered viscosity, the rate of increase in viscosity was calculated from the following general formula. Next, the calculated viscosity increase rate was evaluated according to the following criteria.
Viscosity increase rate (%) = (viscosity after recovery−initial viscosity) / initial viscosity × 100
○: Viscosity increase rate is less than 10% ×: Viscosity increase rate is 10% or more.

<Scratch resistance>
Using a wear resistance tester (model IMC-154A, manufactured by Imoto Seisakusho Co., Ltd.) on the surface of the cured layer (protective layer or hard coat layer) of the obtained substrate / cured layer laminate, a load of 200 g / Under the condition of cm ² , steel wool # 0000 was reciprocated 10 times at a reciprocating speed of 30 mm / second and a reciprocating distance of 25 mm, and then the degree of damage was visually observed and evaluated according to the following criteria.
A: No change (scratches are not recognized)
○: Several or more very shallow scratches are observed. ×: Innumerable deep scratches are observed.

<Surface lubricity of hardened layer>
On the surface of the cured layer (cured film of the composition) of the obtained substrate / cured layer laminate, 1.5 μl of a droplet of trioleic acid glyceride as an artificial fingerprint liquid was applied in an environment at a temperature of 25 ° C. and a humidity of 50%. The contact angle after 0.5 seconds was measured with a fully automatic contact angle meter (model DM500, manufactured by Kyowa Interface Science Co., Ltd.) and evaluated according to the following criteria. The larger the value of the contact angle, the easier it can be wiped off even when fingerprints are attached.
A: Contact angle is 55 ° or more ○: Contact angle is 50 ° or more ×: Contact angle is less than 50 °

<Scratch resistance of hard coat layer>
Using a wear resistance tester (model IMC-154A, manufactured by Imoto Seisakusho Co., Ltd.) on the hard coat layer surface of the laminate (hard coat layer / protective layer / substrate), steel wool under a predetermined load # 0000 was reciprocated 10 times at a reciprocating speed of 30 mm / second and a reciprocating distance of 25 mm, and then the degree of damage was visually observed and evaluated according to the following criteria.
○: No change in load 200 g / cm ² (scratches are not recognized)
×: Several or more scratches are observed at a load of 200 g / cm ²

<Deformation resistance of hard coat layer>
When the hard coat layer of the laminate (hard coat layer / protective layer / substrate (sample size 12 cm × 12 cm)) is used as the top surface, the end of the diagonal line is held, and the hard surface on the laminate is bent until the diagonal distance is 10 cm. Whether or not cracks occurred in the coating layer was visually observed and evaluated according to the following criteria.
○: No cracks are observed Δ: Slight cracks are observed ×: Large cracks are observed

<Pencil hardness>
The surface of the cured product layer of the obtained substrate / cured layer laminate was measured according to JIS-K5400 using a pencil scratch hardness tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.). The load was 1000 g.

≪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 50 ° C. After the temperature rise, 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 were added dropwise over 3 hours to polymerize. Went. After completion of the polymerization, the reaction was terminated by adding triethylamine. Subsequently, after concentration by an evaporator, a vinyl polymer 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. In addition, the number average molecular weight (Mn) of the obtained vinyl polymer is 2210, the molecular weight distribution (Mw / Mn) is 1.60, and the radical polymerizable unsaturated group equivalent is 186.

≪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 raising the temperature, 200 g of 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA, Nippon Shokubai Co., Ltd.), 0.2 g of methanol, 25 g of ethyl acetate and 13 mg of phosphotungstic acid were mixed for 3 hours. Over the course of the polymerization. After completion of the polymerization, the reaction was terminated by adding triethylamine. Subsequently, after concentrating with an evaporator, a vinyl polymer P (VEEA) -2 was obtained. The reaction rate of the monomer was found to be 99.6% by analyzing the mixture after the reaction was stopped by gas chromatography (GC), and the content of ethyl acetate was found to be 0.1%. did. Moreover, the number average molecular weight (Mn) of the obtained vinyl polymer was 970, and molecular weight distribution (Mw / Mn) was 1.60.

<< Preparation of curable resin composition for optical disc and curable resin composition for hard coat layer >>
Each component was mixed and stirred at the ratios shown in Tables 1 to 4 to obtain a curable resin composition for optical disks and a curable resin composition for hard coat layers. The obtained composition was evaluated by the above evaluation method. The evaluation results are shown in Tables 1 to 4. The relationship between the value of A ÷ B and the elastic modulus of the cured product is shown in FIG.

<< Manufacture of optical disks >>
Optical disc No. 1-44
A curable resin composition for an optical disk was applied on a polycarbonate substrate having a thickness of 1.1 mm and dimensions of 120 mm × 120 mm with a spin coater at a thickness of 100 μm. The obtained polycarbonate substrate was cured by irradiation 15 times at a lamp height of 2 cm using a UV irradiator having a xenon flash UV lamp (model RC-742, manufactured by Xenon, USA). The integrated irradiation light quantity at 320 to 390 nm was about 0.6 J / cm ² . The thickness of the protective layer was 100 ± 2 μm. The results of evaluation of the obtained optical disk are shown in Tables 1 to 4.
Optical disc No. 45-88
Using a spin coater, a curable resin composition for an optical disc was applied at a thickness of 100 μm on a polycarbonate (PC) substrate having dimensions of 120 mm × 120 mm and a thickness of 1 mm. The obtained PC substrate was UV-cured with an irradiation integrated light quantity of 500 mJ / cm ² using a UV irradiation machine (manufactured by Eye Graphics Co., Ltd.) having an ultrahigh pressure mercury lamp.

Next, the previously prepared curable resin composition for hard coat layer was applied at a thickness of 3 μm to the PC substrate on which the cured product layer was laminated. Similarly, the obtained PC substrate was UV-cured with an irradiation integrated light quantity of 500 mJ / cm ² using a UV irradiation machine (manufactured by Eye Graphics Co., Ltd.) having an ultrahigh pressure mercury lamp. Table 5 shows the results of evaluation of the obtained optical disk.

Abbreviations in Tables 1 to 7 are as follows.
Curable resin composition material for optical disks / UV-6640B: Urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) (radical polymerizable unsaturated group equivalent; 814)
UV-6100B: urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) (radically polymerizable unsaturated group equivalent; 828)
UV-7000B: urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) (radically polymerizable unsaturated group equivalent; 489)
UV-3000B: urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) (radical polymerizable unsaturated group equivalent; 3588)
CN-981: Urethane acrylate (Sartomer Co., Ltd.) (radically polymerizable unsaturated group equivalent; 709)
CN-978: Urethane acrylate (Sartomer Co., Ltd.) (Radically polymerizable unsaturated group equivalent; 709)
CN-991: Urethane acrylate (Sartomer Co., Ltd.) (radically polymerizable unsaturated group equivalent; 537)
CN-2302: Hyperbranched polyester acrylate (manufactured by Sartomer Japan, Inc.) (number of acrylate functional groups; 16, radical polymerizable unsaturated group equivalent; 40)
P (VEEA) -1: vinyl polymer of Production Example 1 (radical polymerizable unsaturated group equivalent; 186)
P (VEEA) -2: vinyl polymer of Production Example 2 (radical polymerizable unsaturated group equivalent; 186)
Bis-4EO-A: Diacrylate of ethylene oxide 4 mol adduct of bisphenol A (trade name “Light acrylate BP-4EA”, manufactured by Kyoeisha Chemical Co., Ltd.) (radical polymerizable unsaturated group equivalent; 256)
Bis-10EO-A: Diacrylate of ethylene oxide 10 mol adduct of bisphenol A (trade name “SR-602”, manufactured by Sartomer Co., Ltd.) (radically polymerizable unsaturated group equivalent; 388)
PEGDA-9: polyethylene glycol diacrylate (manufactured by Nippon Shokubai Co., Ltd.) (radically polymerizable unsaturated group equivalent; 186)
TMP-6EO-A: triacrylate of trimethylolpropane ethylene oxide 6 mol adduct (trade name “SR-499”, manufactured by Sartomer Co., Ltd.) (radically polymerizable unsaturated group equivalent; 187)
TMP-9EO-A: triacrylate of trimethylolpropane ethylene oxide 9 mol adduct (trade name “SR-502”, manufactured by Sartomer Co., Ltd.) (radically polymerizable unsaturated group equivalent; 231)
VEEA: 2- (2-vinyloxyethoxy) ethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) (ethylenic double bond equivalent; 186)
HX-220: Diacrylate of ε-caprolactone 2-mol adduct of neopentyl glycol hydroxypivalate (trade name “Kayarad (registered trademark) HX-220”, manufactured by Nippon Kayaku Co., Ltd.) (radically polymerizable unsaturated group) Equivalent); 270)
HX-620: Diacrylate of ε-caprolactone 4-mol adduct of neopentyl glycol hydroxypivalate (trade name “Kayarad (registered trademark) HX-620”, manufactured by Nippon Kayaku Co., Ltd.) (radically polymerizable unsaturated group) Equivalent; 384)
Bis-4PO-A: Diacrylate of propylene oxide adduct of bisphenol A (trade name “light acrylate BP-4PA”, manufactured by Kyoeisha Chemical Co., Ltd.) (radical polymerizable unsaturated group equivalent; 568)
Bis-4EO-M: Dimethacrylate of ethylene oxide adduct of bisphenol A (trade name “BPE-200”, manufactured by Shin-Nakamura Chemical Co., Ltd.) (radically polymerizable unsaturated group equivalent; 268)
9EG-A: Polyethylene glycol diacrylate (trade name “Light acrylate 9EG-A”, manufactured by Kyoeisha Chemical Co., Ltd.) (radical polymerizable unsaturated group equivalent; 269)
IB-XA: Isobornyl acrylate (trade name “Light acrylate IB-XA”, manufactured by Kyoeisha Chemical Co., Ltd.) (radical polymerizable unsaturated group equivalent; 208)
DCP-A: tricyclodecane diacrylate (trade name “light acrylate DCP-A”, manufactured by Kyoeisha Chemical Co., Ltd.) (radical polymerizable unsaturated group equivalent: 152)
1,6-Hx-A: 1,6-hexanediol diacrylate (trade name “Light acrylate 1,6Hx-A”, manufactured by Kyoeisha Chemical Co., Ltd.) (radical polymerizable unsaturated group equivalent; 226)
-HPP-A: Neopentyl glycol diacrylate hydroxypivalate (trade name “Light acrylate HPP-A”, manufactured by Kyoeisha Chemical Co., Ltd.) (radically polymerizable unsaturated group equivalent; 156)
IB-XM: isobornyl methacrylate (trade name “Light Ester IB-X”, manufactured by Kyoeisha Chemical Co., Ltd.) (radical polymerizable unsaturated group equivalent; 222)
DPCA-60: Hexaacrylate of 1 mol caprolactone adduct of dipentaerythritol (trade name “Kayarad (registered trademark) DPCA-60, manufactured by Nippon Kayaku Co., Ltd.”
Irg184: 1-hydroxy-cyclohexyl-phenyl-ketone (trade name “Irgacure (registered trademark) 184”, manufactured by Ciba Specialty Chemicals Co., Ltd.)
・ Esacure-one: oligo {2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone} (trade name “Esacure ONE”, manufactured by Lamberti) ・ TINUVIN PS: 2- (2 -Hydroxy-5-t-butylphenyl) -2H-benzotriazole (trade name "Tinuvin (registered trademark) PS", manufactured by Ciba Specialty Chemicals Co., Ltd.)
TINUVIN 479: 2- {2-hydroxy-4- (1-octyloxycarbonylethoxy) phenyl} -4,6-bis (4-phenylphenyl) -1,3,5-triazine (trade name “Tinuvin (registered) Trademark) 479 ", manufactured by Ciba Specialty Chemicals Co., Ltd.)
RUVA93: 2- {2-hydroxy-5- (2-methacryloyloxyethyl) phenyl} benzotriazole (manufactured by Otsuka Chemical Co., Ltd.)
BY16-876: Epoxy-modified silicone (manufactured by Dow Corning Toray)
Hard coating curable resin composition material PET-4EO-A: Tetraacrylate of 4-pentaerythritol ethylene oxide 4-mole adduct (trade name “SR494”, manufactured by Sartomer Co., Ltd.)
PET-8EO-A: Tetraacrylate of 8-pentapentylerythritol ethylene oxide adduct DPCA-60: Hexaacrylate of 1-mol adduct of dipentaerythritol caprolactone (trade name “Kayarad (registered trademark) DPCA-60, Nippon Kayaku Co., Ltd.
CN-2300: Hyperbranched polyester acrylate (8 acrylate functional groups, manufactured by Sartomer Japan, Inc.)
CN-2302: Hyperbranched polyester acrylate (16 acrylate functional groups, manufactured by Sartomer Japan, Inc.)
CN-2304: Hyperbranched polyester acrylate (18 acrylate functional groups, manufactured by Sartomer Japan, Inc.)
-Biscoat # 1000: Dendrimer type acrylate (Osaka Organic Chemical Co., Ltd.)-Biscoat # 1020: Dendrimer type acrylate (Osaka Organic Chemical Co., Ltd.)-P- (VEEA) -2: Vinyl-based weight of Production Example 2 Combined VEEA: 2- (2-vinyloxyethoxy) ethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) NP-2PO-A: Diacrylate of propylene oxide 2-mol adduct of neopentyl glycol (trade name “SR-9003” "Sartomer Co., Ltd.)
・ TPGDA: Tripropylene glycol diacrylate (trade name “SR-306H”, manufactured by Sartomer Co., Ltd.)
TMP-3EO-A: triacrylate of trimethylolpropane adduct with 3 moles of ethylene oxide (trade name “SR-454”, manufactured by Sartomer Co., Ltd.)
DPHA: Dipentaerythritol hexaacrylate (trade name “Light acrylate DPE-6A”, manufactured by Kyoeisha Chemical Co., Ltd.)
PETA: pentaerythritol triacrylate (trade name “Light acrylate PE-3A”, manufactured by Kyoeisha Chemical Co., Ltd.)
PET-12EO-A: Tetraacrylate of 12-mole ethylene oxide adduct of pentapentaerythritol TMPTA: Trimethylolpropane triacrylate (manufactured by Nippon Shokubai)
L-7002: Polyether-modified silicone (trade name “L-7002”, manufactured by Toray Dow Corning Co., Ltd.)
D1173: 2-hydroxy-2-methyl-1-phenyl-propan-1-one (trade name “Darocur 1173”, manufactured by Ciba Specialty Chemicals)

The curable resin composition for an optical disc of the present invention has transparency and suppresses warpage of the entire optical disc, and further has long-term storage stability (low warpage and high temperature environment in a storage test under a high temperature environment and a low temperature environment). It is possible to use for an optical disc, for example, a Blu-ray disc (registered trademark), which is excellent in the residual film property below and a small amount of permanent deformation such as a dent.

Claims

A curable resin used for an optical disc having a reflective film that is present on a substrate and reflects a laser beam for reading information, and a protective layer that is present on the reflective film and has a thickness of 20 μm to 150 μm. A composition comprising:
Oligomer and / or polymer having at least one radical polymerizable group selected from the group consisting of urethane (meth) acrylate, epoxy (meth) acrylate, and polyester (meth) acrylate, and an alkylene oxide adduct-containing polyfunctional (meth) Containing acrylic acid esters or caprolactone adduct-containing polyfunctional (meth) acrylic acid esters, and a photopolymerization initiator,
The radical polymerizable unsaturated group equivalent (g / eq) in the curable resin composition is A, the alkylene oxide adduct-containing polyfunctional (meth) acrylic acid ester and the caprolactone adduct are contained in the curable resin composition. A curable resin composition for an optical disk, wherein the content (mass%) of the polyfunctional (meth) acrylic acid ester is B, and satisfies 6.6 ≦ A ÷ B ≦ 35.
The curable resin composition for optical disks according to claim 1, wherein the polyfunctional (meth) acrylic acid ester containing an alkylene oxide adduct is a diacrylate of an alkylene oxide adduct of bisphenol A.
The curable resin composition for an optical disk according to claim 1 or 2, wherein the curable resin composition has a viscosity at 25 ° C of 800 mPa · s to 3500 mPa · s.
The curable resin composition for an optical disk according to any one of claims 1 to 3, wherein the cured product obtained by curing the curable resin composition has a storage elastic modulus E 'at 25 ° C of 10 MPa or more and 150 MPa or less.
The curable resin composition for an optical disc according to any one of claims 1 to 3, wherein the cured product obtained by curing the curable resin composition has a storage elastic modulus E 'at 25 ° C of from 1200 MPa to 2100 MPa.
The curable resin composition for an optical disc according to any one of claims 1 to 5, wherein the curable resin composition contains a polyfunctional (meth) acrylate and / or a multibranched reactive compound.
The light transmittance of each wavelength at a thickness of 100 μm of a cured product obtained by curing the curable resin composition,
(X) 85.0% or more at 400 nm,
(Y) 35.0% or more and 85.0% or less at 380 nm, and
(Z) The curable resin composition for an optical disc according to any one of claims 1 to 6, which is 0.1% or more and 50.0% or less at 360 nm.
An optical disc comprising a protective layer obtained by curing the curable resin composition for an optical disc according to any one of claims 1 to 7.
Hard obtained by curing a resin composition for hard coat, which is formed directly on the protective layer and contains a hyperbranched reactive compound and / or a polymer having a reactive group in a side chain, and a polymerization initiator. The optical disk according to claim 8, further comprising a coat layer.
The optical disk according to claim 9, wherein the multi-branched reactive compound (α) is a dendrimer (α1) and / or a hyperbranched polymer (α2) having two or more reactive groups at its terminal.
An alkylene oxide adduct-containing polyfunctional product obtained from an alkylene oxide adduct wherein n = 1 or 2 is added to a tetravalent or higher polyhydric alcohol directly formed on the protective layer. Caprolactone adduct-containing polyfunctional (meth) acrylic obtained from a caprolactone adduct having n = 1 or 2 per 1 valence addition unit to a (meth) acrylic acid ester and / or a tetrahydric or higher polyhydric alcohol The optical disk according to claim 8, further comprising a hard coat layer obtained by curing a hard coat resin composition containing an acid ester and a photopolymerization initiator.