JP2004220755A - Optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical disk which has satisfactory optical characteristics and prevents the occurrence of warpage when the optical disk is used. <P>SOLUTION: In the optical disk, a recording layer, an adhesive layer and a light transmission layer are successively layered on at least one surface of a supporting substrate, the thermal expansion ratio of the thermal expansion quantity in the uniaxial direction of the supporting substrate at 30 to 80°C to the thermal expansion quantity in the uniaxial direction of the light transmission layer at 30 to 80°C is in the range of 0.75 to 1.25 and the light transmission layer consists essentially of a thermoplastic resin. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an optical disk such as a compact disk (CD), a DVD or a magneto-optical recording disk, and more particularly to an optical disk such as a large-capacity high-density DVD having a recording capacity of 20 GB or more.

  Optical discs have a recording layer on one side of a support substrate made of a transparent plastic substrate that records signal information consisting of bit strings and grooves with fine irregularities. This system records and reproduces information by irradiating light such as light and utilizing the fact that the amount of reflected light changes in accordance with signal information on a support substrate.

  Examples of the type of the optical disk include a compact disk (CD: Compact Disk), a DVD (Digital Versatile Disk), and a magneto-optical recording disk.

  In a typical optical disc, CD, a transparent light transmission layer for reading information is formed on a support substrate having a thickness of 0.6 mm, and the light transmission layer has a structure also serving as a support substrate having a recording layer. is there. In a CD, a laser beam having a wavelength of 780 nm is used for recording / reproducing, and a laser beam for recording / reproducing is irradiated from the light transmitting layer side, and according to signal information composed of bit strings and grooves imprinted on the recording layer on the support substrate. The information recorded on the recording layer is reproduced based on the amount of reflected light which changes.

  In a DVD having a larger recording capacity than a CD, a laser beam having a wavelength of 635 nm is used for recording and reproduction. However, basically, similarly to the above-described CD, the recording layer is irradiated with the laser beam to record signal information. Perform recording and playback.

  FIG. 3 is a partially enlarged perspective view of the DVD for schematically explaining the structure of the DVD, and FIG. 4 is a cross-sectional view thereof. As shown in FIGS. 3 and 4, the DVD 10 includes a support base 11, a recording layer 12 formed on the support base 11, and a light transmission layer 13 formed on the recording layer 12. More specifically, in a single-layer plate, the thickness of the transparent support base 11 from which information is read is 0.6 mm, and information such as 14 rows of bits and recording grooves is recorded on the support base 11. The recording layer 12 is formed, and a transparent support substrate having the same thickness (0.6 mm) as the support substrate 11 is laminated on the recording layer 12 to form the light transmitting layer 13. The light transmitting layer 13 formed on the recording layer 12 is usually called a “dummy” and plays a role of improving the strength of the optical disc itself. As shown in FIGS. 3 and 4, a laser beam 15 is irradiated from the light transmission layer 13 side to record and reproduce information on the recording layer.

  Further, in recent years, with the development of video information, moving image information, and the like, a DVD having a large recording capacity has been required, and a high-density DVD called a next-generation disc having a recording capacity exceeding 20 GB has been developed. Have been. The high-density DVD has a size of 12 cm in diameter, which is the same size as the conventional one. Since the recording layer has the same size as that of the related art, it is required that the recording layer be miniaturized by narrowing the track pitch or the bit length to achieve high density.

  Specifically, a recording layer on which signal information is recorded by a bit array or a groove is formed on a support base having a thickness of about 1.1 mm, and a transparent film having a thickness of about 0.1 mm is formed on the surface of the recording layer. To form a light transmitting layer. Then, a blue laser having a short wavelength of about 400 nm is irradiated from the surface side of the light transmission layer to record and reproduce signal information.

It has been reported that, for example, polycarbonate having good strength characteristics and optical characteristics is used as a material of a support base and a light transmitting layer (dummy layer) of the above-described CD, DVD, next-generation disk, etc. 1 and Patent Document 2), polycarbonate is also used as the recording layer of the next-generation DVD. Further, the use of various materials other than polycarbonate as the light transmission layer of the next-generation DVD is being studied.
JP 2000-67468 A JP 2001-243659 A

  However, the above-described light transmission layer transmits and transmits laser light having a short wavelength of about 400 nm to record and reproduce signal information imprinted on the recording layer. There is a problem that the reflected light from the light is absorbed when passing through the light transmitting layer, and the signal intensity is reduced. Therefore, in order to obtain high signal accuracy, it is required that the light transmission layer has a high light transmittance of a short wavelength laser of about 400 nm in the light transmission layer, and a material having a good light transmittance is desired.

  Since acrylic resin has a high degree of transparency, various attempts have been made to apply it to an optical disk using a laser having a short wavelength of about 400 nm. However, although acrylic resin has high transparency, when a light transmitting layer made of acrylic resin is applied to an optical disc, for example, a film for light transmitting layer made of acrylic resin and a support base made of a material other than acrylic resin are used. When an optical disc is formed by laminating films for use with an optical disc, a problem arises in that the optical disc is warped during use. In particular, a high-density optical disk having a large capacity has a problem that the optical disk is likely to be warped because the thickness of the light transmission layer and the supporting substrate is extremely thin as described above. When the optical disk itself warps, when recording and reproducing the optical disk by irradiating a laser beam, a large deviation occurs in the direction of the reflected light, and it is impossible to accurately reproduce and record the signal information of the recording layer. Had a problem.

  In addition, in order to reduce the warpage, it is improved by increasing the storage elastic modulus of the acrylic resin.However, when the storage elastic modulus is increased, the hardness of the acrylic resin surface is reduced, so that the acrylic resin is easily damaged in practical use. There is a problem that. When the dust is wiped off, or when the surface of the light transmitting layer is finely scratched due to contact with something, the laser light itself does not reach the recording layer, or the intensity of the reaching light and reflected light is significantly reduced. Cannot be read accurately, and as a result, there is a problem that the recording capacity is reduced.

  The present invention has been made to solve the above problems, and has as its object to obtain an optical disk having good optical characteristics and preventing warpage during use.

  Another object of the present invention is to obtain an optical disk having excellent surface scratch resistance in practical use in addition to the above.

  The cause of the warpage is that the materials of the support base and the light-transmitting layer are different, and the influence of the difference in the amount of water absorption in the use environment and the difference in the volume fluctuation due to the difference in the amount of thermal expansion is affected. Yes, and in particular, the amount of thermal expansion is due to intrinsic properties inherent in the material. For this reason, the present inventors conducted various studies on the occurrence of warpage by variously changing the respective thermal expansion amounts of the light transmitting layer and the support base applied to the optical disc, and as a result, determined that the thermal expansion amount between the support base and the light transmission layer was a predetermined value. The inventors have found that the occurrence of warpage can be reduced by defining the range, and the present invention has been completed.

  That is, the present invention relates to an optical disc in which a recording layer, an adhesive layer and a light transmitting layer are sequentially laminated on at least one surface of a support base, and the amount of thermal expansion of the light transmitting layer in the uniaxial direction at 30 ° C. to 80 ° C. The thermal expansion ratio, which is the amount of thermal expansion of the support base in the uniaxial direction at 30 ° C. to 80 ° C., is in the range of 0.75 to 1.25, and the light transmission layer is mainly made of a thermoplastic resin. It is characterized by the following.

  Furthermore, by providing a hard coat layer having a pencil hardness of 3H or more on the light transmitting layer of the optical disc of the present invention, the scratch resistance in practical use was improved, and the occurrence of warpage and the ease of damage were successfully reduced at the same time. did.

  According to the present invention, it is possible to significantly reduce the warpage of a disk during long-term use of the optical disk and during an environmental resistance promotion test, and as a result, it is possible to improve the reading accuracy and the writing accuracy of the recording layer. . Further, by forming the hard coat layer on the light transmitting layer of the optical disk, it is possible to provide a higher quality optical disk having excellent scratch resistance in actual use. As a result, it is possible to realize an increase in the recording capacity required for an optical disk with the development of video information, moving image information, and the like.

  In the present invention, the thermal expansion ratio of the support base to the light-transmitting layer is specified to be in the range of 0.75 to 1.25, but is more preferably 0.8 to 1.2, and still more preferably 0.1 to 1.2. It is in the range of 9 to 1.1. When the thermal expansion ratio is smaller than 0.75, the disk warps in a direction in which the light transmitting layer contracts during an environmental test or during actual use for a long period of time, and the reading accuracy and the writing accuracy of the recording layer decrease, and the thermal expansion ratio decreases. If 1.25 exceeds 1.25, the disk warps in the direction in which the light transmitting layer expands during an environmental test or during actual use for a long period of time, and reading accuracy and writing accuracy in the recording layer are reduced.

  In the present invention, as the thermoplastic resin forming the light transmitting layer, the thermal expansion of the support base in the uniaxial direction of 30 ° C. to 80 ° C. with respect to the thermal expansion amount of the light transmitting layer in the uniaxial direction of 30 ° C. to 80 ° C. Any material can be used as long as its thermal expansion ratio is in the range of 0.75 to 1.25. For example, it can be appropriately selected from acrylic resin, polycarbonate resin, polyolefin resin, cellulose resin and the like. Among these resins, the acrylic resin described below is most preferable in consideration of various properties such as easiness of modification, high transparency, and low birefringence.

  Further, in the optical disc of the present invention, it is preferable that the birefringence of the light transmitting layer is 20 nm or less. If the birefringence exceeds 20 nm, the signal accuracy at the time of writing to and reading from the optical disk tends to decrease. The birefringence is preferably 10 nm or less, more preferably 5 nm or less, and particularly preferably 2 nm or less in the case of a high-density DVD exceeding 20 GB in terms of signal accuracy.

Further, in the optical disc of the present invention, the thickness of the light transmitting layer is preferably 15 to 250 μm, more preferably 25 to 200 μm, and further preferably 35 to 150 μm. When the thickness of the light transmitting layer is less than 15 μm, the toughness is reduced, and the workability at the time of processing tends to deteriorate. Conversely, when the thickness exceeds 250 μm, volatile substances such as solvents and monomers tend to remain, and This is because a good film cannot be obtained. The measurement of the thickness of the light transmission layer, a laser focus displacement meter (manufactured by Keyence Corporation, LT-8010) with, any size for (e.g. ^{1cm 2 ~10000cm} 2 plane), suitably from whole ( (For example, 25 to 1000 points) Measurement points can be selected and measured, and the average value can be used as the thickness.

  In the optical disc of the present invention, the light transmittance of the light transmitting layer at a wavelength of 405 nm is preferably 87% or more, more preferably 90% or more. If the light transmittance is less than 87%, the reflected light from the recording layer is absorbed when passing through the light transmitting layer, and the signal intensity is reduced. In order to make the light transmittance 87% or more, for example, it can be adjusted by not using an additive that absorbs ultraviolet rays or using only a monomer that does not have an ultraviolet absorption band in a monomer constituting the resin. .

  Examples of these detailed measuring methods will be described in Examples.

  As the thermoplastic resin forming the light transmitting layer, the thermal expansion ratio which is the amount of thermal expansion of the support base in the uniaxial direction at 30 ° C. to 80 ° C. with respect to the amount of thermal expansion of the light transmitting layer in the uniaxial direction at 30 ° C. to 80 ° C. Any one can be used as long as it is within the range of 0.75 to 1.25, but acrylic resins are most preferred in view of various properties such as easiness of modification, high transparency, and low birefringence. It is suitable.

The acrylic resin is obtained by polymerizing a monomer having a reactive double bond, and is not particularly limited. For example, the following resins can be used. Methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, pentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-acrylate Octyl, dodecyl acrylate, octadecyl acrylate, butoxyethyl acrylate, phenyl acrylate, benzyl acrylate, naphthyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, cyclohexyl acrylate, methylcyclohexyl acrylate, trimethyl acrylate Cyclohexyl, norbornyl acrylate, norbornyl methyl acrylate, cyanonorbornyl acrylate, isobornyl acrylate, bornyl acrylate, menthyl acrylate, fentyl acrylate Adamantyl acrylate, dimethyl adamantyl, acrylic acid tricyclo [5.2.1.0 ^{2, 6]} dec-8-yl, acrylic acid tricyclo [5.2.1.0 ^{2, 6]} deca-4-methyl Acrylates such as cyclodecyl acrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, n-hexyl methacrylate, methacrylic acid 2 -Ethylhexyl, n-octyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, butoxyethyl methacrylate, phenyl methacrylate, naphthyl methacrylate, glycidyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, methylcyclo methacrylate Xyl, trimethylcyclohexyl methacrylate, norbornyl methacrylate, norbornylmethyl methacrylate, cyanonorbornyl methacrylate, phenylnorbornyl methacrylate, isobornyl methacrylate, bornyl methacrylate, menthyl methacrylate, fentyl methacrylate, methacrylic acid Adamantyl, dimethyl adamantyl methacrylate, tricyclo [5.2.1.0 ^2,6 ] dec-8-yl methacrylate, tricyclo [5.2.1.0 ^2,6 ] deca-4-methyl methacrylate, methacryl Methacrylates such as cyclodecyl acid, α-methylstyrene, α-ethylstyrene, α-fluorostyrene, α-chlorostyrene, α-bromostyrene, fluorostyrene, chlorostyrene, bromostyrene, methylstyrene, methacrylate Aromatic vinyl compounds such as xylstyrene, calcium acrylate, barium acrylate, lead acrylate, tin acrylate, zinc acrylate, calcium methacrylate, barium methacrylate, lead methacrylate, tin methacrylate, zinc methacrylate, etc. (Meth) metal salts of acrylic acid, unsaturated fatty acids such as acrylic acid and methacrylic acid, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, and N-i-propyl Maleimide, N-butylmaleimide, Ni-butylmaleimide, Nt-butylmaleimide, N-laurylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, N-phenylmaleimide, N- (2-chlorophenyl) maleimide, N (4-chlorophenyl) maleimide, N- (4-bromophenyl) phenylmaleimide, N- (2-methylphenyl) maleimide, N- (2-ethylphenylmaleimide, N- (2-methoxyphenyl) maleimide, N- ( 2,4,6-trimethylphenyl) maleimide, N- (4-benzylphenyl) maleimide, N- (2,4,6-tribromophenyl) maleimide, 2,2,6,6-tetramethylpiperidyl methacrylate, 2,2,6,6-tetramethyl-N-methylpiperidyl methacrylate and the like. These may be used alone or in combination of two or more, and are not limited to those shown here.

  In the present invention, the thermoplastic resin forming the light transmitting layer may be a vinyl copolymer containing at least one kind of proton donating group and at least one kind of proton accepting group. Preferably, a pseudo bridge is formed between both atomic groups by an intermolecular hydrogen bond. Further, as the vinyl polymer, an acrylic polymer produced using an acrylic acid or methacrylic acid ester as a main monomer is particularly preferable from the viewpoint of film properties such as transparency.

  When the vinyl polymer is an acrylic polymer (acrylic resin), its molecular weight is not particularly limited. However, in terms of toughness and heat resistance, the weight average molecular weight (measured by gel permeation chromatography) , A value converted using a standard polystyrene calibration curve) is preferably in the range of 10,000 to 1,000,000.

  Further, for the purpose of improving the lack of flexibility, which is a drawback of the acrylic resin, it is preferable to use a flexible acrylic resin, and it is possible to add rubber particles having the same refractive index or a highly flexible acrylic resin. It can also be blended. As a method of blending a highly flexible acrylic resin, for example, a method described in JP-A-2000-273319 or JP-A-2002-38036 is known. According to this method, when an acrylic resin having a proton-accepting atomic group and an acrylic resin having a proton-donating atomic group are blended, an intermolecular hydrogen bond is formed, and the acrylic resin composition as a blended product is formed. Things have high transparency.

  Further, in the above invention, as the vinyl polymer, a vinyl polymer A having at least one kind of proton donating atomic group and a vinyl polymer B having at least one kind of proton accepting atomic group can be used. It is preferable to use a mixture in which a pseudo cross-link is formed in the mixture by intermolecular hydrogen bonding. Here, the term “pseudo” is used, but the term “pseudo” means that the crosslinked structure is cut by heat (below the thermal decomposition temperature) or a solvent, and the crosslinked structure is reduced again by lowering the temperature or removing the solvent. This is because it can be estimated that it is formed. Hereinafter, the vinyl polymer A and the vinyl polymer B will be described.

[Vinyl polymer A]
The vinyl polymer A is a polymer having at least one kind of proton donating atomic group, and has at least one kind of functional group selected from a carboxyl group, a hydroxyl group and a phenolic hydroxyl group. It can be obtained by copolymerizing with a monomer. For example, acrylic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, 2-acryloyloxyethyl- 2-hydroxypropyl phthalate, 2-acryloyloxyethyl acid phosphate, 2-hydroxy-3-acryloyloxypropyl acrylate, methacrylic acid, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-hydroxypropyl methacrylate Methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-methacryloyl B carboxymethyl ethyl acid phosphate, 2-hydroxy-3-methacryloyloxy propyl acrylate, vinyl phenol, vinyl benzoate, vinyl benzoate, and derivatives thereof. These may be used alone or in combination of two or more, and are not limited to those exemplified here.

  When a vinyl monomer having at least one functional group selected from a carboxyl group, a hydroxyl group and a phenolic hydroxyl group in a molecule is copolymerized with another vinyl monomer, a vinyl polymer is used. It is preferable that the vinyl monomer having the above-mentioned functional group is added in an amount of 0.2 mol% or more to the vinyl monomer constituting the main constituent part of A and copolymerized, more preferably 0.5 mol% The copolymerization is preferably carried out as described above, and more preferably, 1.0 mol% or more is added for copolymerization. If the amount is less than 0.2 mol%, the number of intermolecular hydrogen bonding points decreases, the solubility decreases, and the transparency of the obtained thermoplastic resin tends to be impaired.

  In order to produce the vinyl polymer A having a proton donating group in the present invention, using the above-mentioned materials, an existing method such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization is applied. Can be.

  When performing polymerization, a polymerization initiator can be used. Examples of the polymerization initiator include benzoyl peroxide, lauroyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanoate, 1,1-t-butylperoxy-3, Organic peroxides such as 3,5-trimethylcyclohexane, azo compounds such as azobisisobutyronitrile, azobis-4-methoxy-2,4-dimethylvaleronitrile, azobiscyclohexanone-1-carbonitrile, and azodibenzoyl Any of those that can be used for ordinary radical polymerization, such as a water-soluble catalyst such as potassium persulfate and ammonium persulfate and a redox catalyst obtained by combining a peroxide or a persulfate with a reducing agent, can be used. Is not limited to The polymerization initiator is preferably used in the range of 0.01 to 10% by weight based on the total amount of the monomers used for producing the vinyl polymer.

  Further, as a molecular weight regulator, a mercaptan compound, thioglycol, carbon tetrachloride, α-methylstyrene dimer, or the like can be added as necessary. Further, the present invention is not limited to those shown here.

  In the case of thermal polymerization, the polymerization temperature can be appropriately selected from 0 ° C to 200 ° C, and is preferably in the range of 50 ° C to 120 ° C.

  The molecular weight of the vinyl polymer A having a proton-donating atomic group in the present invention is not particularly limited. However, in terms of toughness and heat resistance, the weight average molecular weight (measured by gel permeation chromatography and standard polystyrene calibration) (Value converted using a line) is preferably in the range of 10,000 to 1,000,000, and more preferably in the range of 100,000 to 1,000,000.

[Vinyl polymer B]
The vinyl polymer B having a proton accepting group is a polymer having at least one kind of proton accepting group, and can be obtained by polymerizing a monomer having a reactive double bond. There is no particular limitation as long as optical characteristics such as transparency, birefringence and the like are not impaired. As the monomer having a reactive double bond, the same monomers as those used for the vinyl polymer A described above can be used.

  The vinyl polymer B having a proton-accepting atomic group is a monomer having at least one proton-accepting atomic group, preferably an atomic group having a nitrogen atom, in an ordinary vinyl polymer and / or copolymer. It can be obtained by introducing a compound, but as a method for introducing a nitrogen atom into a molecule, the following monomers may be copolymerized during the polymerization of a vinyl monomer. For example, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2,2,6,6-tetramethyl N-methylpyrimidyl methacrylate, 2,2,6,6 -Tetramethyl N-methylpyrimidyl acrylate, 2,2,6,6-tetra-N-methylpiperidyl methacrylate, 2,2,6,6-tetramethylpiperidyl methacrylate, dimethylaminoethyl methacrylate, acrylamide, methacrylamide, (Meth) acrylamides such as N-dimethylacrylamide, N-diethylacrylamide, N-dimethylmethacrylamide, N-diethylmethacrylamide, vinylpyridine and derivatives thereof And the like. Further, the present invention is not limited to those shown here.

  The amount of the monomer for introducing at least one nitrogen atom into the molecule of the vinyl polymer B having a proton-accepting atomic group may be, for example, as follows. It is preferably at least 0.2 mol%, more preferably at least 0.5 mol%, more preferably at least 1.0 mol%, based on the vinyl monomer constituting the main constituent part. preferable. When the amount is less than 0.2 mol%, the solubility is deteriorated because the number of intermolecular hydrogen bonding points is reduced, and the transparency of the obtained resin composition tends to be impaired. Is preferred.

  For the production of the vinyl polymer B having a proton-accepting atomic group in the present invention, existing methods such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization using the above-mentioned materials can be applied.

  When performing polymerization, a polymerization initiator can be used. Examples of the polymerization initiator include benzoyl peroxide, lauroyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanoate, 1,1-t-butylperoxy-3, Organic peroxides such as 3,5-trimethylcyclohexane, azo compounds such as azobisisobutyronitrile, azobis-4-methoxy-2,4-dimethylvaleronitrile, azobiscyclohexanone-1-carbonitrile, and azodibenzoyl Any of those that can be used for ordinary radical polymerization, such as water-soluble catalysts such as potassium persulfate and ammonium persulfate, and redox catalysts using a combination of a peroxide or a persulfate and a reducing agent can be used. Further, the present invention is not limited to those shown here. The polymerization initiator is preferably used in a range of 0.01% by weight to 10% by weight based on the total amount of the monomers used for producing the vinyl polymer A having a proton donating atomic group.

  Further, as a molecular weight regulator, a mercaptan compound, thioglycol, carbon tetrachloride, α-methylstyrene dimer, or the like can be added as necessary. Further, the present invention is not limited to those shown here.

  In the case of thermal polymerization, the polymerization temperature can be appropriately selected from 0 to 200 ° C, and is preferably in the range of 50 ° C to 120 ° C.

  The molecular weight of the vinyl polymer B having a proton accepting atomic group is not particularly limited, but the weight average molecular weight (in terms of polystyrene) is in the range of 10,000 to 1,000,000 from the viewpoint of toughness and heat resistance. Are preferred.

[Mixing of vinyl polymer A and vinyl polymer B]
When mixing the vinyl polymer A having a proton donating group and the vinyl polymer B having a proton accepting group, the mixing ratio of the vinyl polymer A and the vinyl polymer B is There is no particular limitation as long as the transparency of the obtained resin composition is ensured, but from the viewpoint of toughness, heat resistance, and transparency, each hydrogen bond between the vinyl polymer A and the vinyl polymer B Is preferably mixed at a molar ratio of the atomic groups capable of forming the compound of formula (1) to a mixing ratio of 15: 1 to 1:15. More preferably, the molar ratio of one or more functional groups selected from the carboxyl group, hydroxyl group and phenolic hydroxyl group in the vinyl polymer A to the nitrogen atom-containing group in the vinyl polymer B is 15 It is preferable to mix at a mixing ratio of 1: 1 to 15: 1.

  The pseudo-crosslinked resin composition suitably used for the optical disc of the present invention is obtained by mixing the above-mentioned vinyl polymer A having a proton donating atomic group and the vinyl polymer B having a proton accepting atomic group. It is also possible to appropriately add a vinyl polymer for the purpose of improving flexibility or heat resistance.

  In the present invention, the pseudo-crosslinked resin composition refers to a resin composition crosslinked by hydrogen bonding. Simulated means that the crosslinked structure is cut by heat (below the thermal decomposition temperature) or a solvent, and the crosslinked structure is formed by lowering the temperature or removing the solvent.

  In the present invention, the method of mixing the vinyl polymer A having a proton donating atom group and the vinyl polymer B having a proton accepting atom group is not particularly limited, such as a melt kneading method and a varnish blending method.

  The amount of thermal expansion of a blend of a vinyl polymer A having a proton donating group and a vinyl polymer B having a proton accepting group was determined by measuring the amount of thermal expansion of the vinyl polymer A having a proton donating group alone. In order to make the thermal expansion amount smaller than the thermal expansion amount of the vinyl polymer B having a proton-accepting atomic group alone, or from the carboxyl group, hydroxyl group and phenolic hydroxyl group in the proton-donating atomic group. Preferably, the molar ratio of one or more functional groups to the nitrogen-containing group in the proton-accepting atomic group is in the range of 5: 1 to 1: 5. It is preferable that the ratio be in the range of 1: 2.

  In the present invention, the vinyl polymer A having a proton donating group and the vinyl polymer B having a proton accepting group preferably have different glass transition temperatures, and one of the glass transition temperatures is less than 25 ° C. And the other glass transition temperature is more preferably 25 ° C. or higher. By mixing the vinyl polymer A and the vinyl polymer B having different glass transition temperatures, heat resistance and flexibility can be imparted to the obtained vinyl polymer. When the temperature is out of the above-mentioned temperature condition, flexibility cannot be imparted at room temperature, and there is a tendency that a problem of thermal deformation occurs. However, one is preferably + 10 ° C. or lower and the other is + 50 ° C. or higher, and more preferably one is 0 ° C. or lower and the other is + 80 ° C. or higher. In the present invention, the glass transition temperature can be measured by DVA (dynamic viscoelasticity measurement), TMA, DSC method or the like, and it is preferable to use DVA (dynamic viscoelasticity measurement) as a reference, which will be described later. Also in the examples, the measurement is performed by DVA.

  In order to impart flexibility, the glass transition temperature of one of the vinyl polymer A and the vinyl polymer B is preferably set to less than 25 ° C., but either may be used. Therefore, in the production of an arbitrary polymer, a vinyl polymer is reduced to a target glass transition temperature or lower by copolymerizing with a monomer having a glass transition temperature of a homopolymer lower than 25 ° C. (preferably 0 ° C.). Can be prepared.

  The above-described thermoplastic resin can be processed into a film, a sheet, or a molding material, and applied as a light transmitting layer of an optical disc. In addition, when a thermoplastic resin or a vinyl polymer is used as a film, a sheet, or a molding material, optional components can be added as necessary. For example, antioxidants such as phenolic antioxidants, phosphite antioxidants and thioether antioxidants are contained in thermoplastic resins from various viewpoints such as deterioration prevention, thermal stability, moldability and processability. Preferably, at least one compound selected from light stabilizers is contained. More specifically, the antioxidant and the light stabilizer will be described.

The phenolic antioxidant used here is not particularly limited as long as the transparency and low birefringence of the thermoplastic resin used as the light transmitting layer are not reduced. For example, antioxidants represented by the following structural formulas (1) to (8) can be used.

The phosphite-based antioxidant is not particularly limited as long as the transparency and birefringence of the thermoplastic resin used as the light transmitting layer are not reduced. For example, the phosphite-based antioxidants include the following structural formulas (9) to (21). The antioxidants shown can be used.

The thioether-based antioxidant is not particularly limited as long as the transparency and birefringence of the thermoplastic resin used as the light transmitting layer are not reduced. For example, the thioether-based antioxidants are represented by the following structural formulas (22) to (24). Antioxidants can be used.

The light stabilizer used in the present invention is not particularly limited as long as the transparency and low birefringence of the thermoplastic resin used as the light transmitting layer are not reduced. The light stabilizer represented by the structural formula (34) can be used.

  The additives of the antioxidant and the light stabilizer can be used alone or in combination of two or more. The amount of the additive can be determined as needed, and it is generally preferable to add the additive in an amount of 1.0% by weight or less based on the solid content of the thermoplastic resin used in the production of the light transmitting layer. It is preferable to add it by weight percent or more. If the amount of the additive exceeds 1.0% by weight, the transparency of the thermoplastic resin tends to decrease. In particular, when using a film produced by heating and melting as the light transmitting layer, it is desirable to add the antioxidant exemplified above. If the antioxidant is not added, coloring due to oxidative deterioration occurs during processing, which may reduce the transparency of the thermoplastic resin. However, when processing can be performed at a relatively low temperature (about 200 ° C. or less), an antioxidant need not be added. The light stabilizer can be added according to the light stability of the thermoplastic resin. Release agents such as aliphatic alcohols, fatty acid esters, phthalic esters, triglycerides, fluorine-based surfactants, higher fatty acid metal salts, and other lubricants, plasticizers, antistatic agents, ultraviolet absorbers, flame retardants, and heavy metal inerts An agent or the like may be added.

  These additives can be used alone or in combination of two or more. The amount of each addition can be determined as needed. However, if added in excess of 1.0%, the transparency of the thermoplastic resin tends to decrease.

  Others include release agents such as aliphatic alcohols, fatty acid esters, phthalic esters, triglycerides, fluorine-based surfactants, higher fatty acid metal salts, and other lubricants, plasticizers, antistatic agents, ultraviolet absorbers, and flame retardants. And a heavy metal deactivator may be added.

  In the present invention, a film or a sheet can be obtained by volatilizing an organic solvent from a resin used for the light transmitting layer by a melt-kneading method, a solvent casting method, or the like.

  The conditions for the casting are not particularly limited. For example, the casting can be performed in air or an inert gas at a temperature of 80 to 160 ° C. The solvent used here is not particularly limited as long as the vinyl polymer can be dissolved. For example, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, aromatic solvents such as toluene and xylene, NMP, dimethylacetamide and the like can be used. What is shown here is an example and is not limited to these.

  After pre-drying is performed under these conditions, the pre-drying is further performed at a high temperature of 160 to 350 ° C., so that the drying time can be reduced.

  The resulting film or sheet is tough and flexible, and has excellent mechanical properties. The resulting film or sheet has suitable flexibility, as shown in the examples later, having suitable flexibility. In addition, since the adhesiveness to metals such as glass, aluminum, and copper is particularly high, the selection of a cast substrate is important in producing films and sheets.

  Specifically, stainless steel, PET film, Teflon (registered trademark) film, and the like can be selected, but are not limited thereto as long as the adhesion to the resin composition is low.

  In addition, the production conditions are not particularly limited in the case of production by a melt-kneading method. For example, the composition is melted in air at a temperature of about 180 ° C. to 250 ° C., extruded through a suitably adjusted gap, and while maintaining its shape. The film can be produced by cooling. It is better to add a stabilizer such as an antioxidant for processing at a high temperature.

  The above-described thermoplastic resin can be used as a light transmission layer of an optical disc including at least a support base, a recording layer, an adhesive layer, and a light transmission layer. Further, the support base and the recording layer in the present invention are not particularly limited, and conventional ones can be used.

  The adhesive layer in the present invention is not particularly limited as long as the transparency is not impaired. For example, an ultraviolet curable resin, a pressure-sensitive adhesive film, or the like can be used.

  In the above invention, the difference in refractive index between the light transmitting layer and the adhesive layer is preferably 0.1 or less. Further, it is more preferably 0.05 or less, and still more preferably 0.01 or less. If the refractive index difference between the light transmitting layer and the adhesive layer exceeds 0.1, irregular reflection of laser light occurs at the interface between the adhesive layer and the light transmitting layer, and the signal reading and writing accuracy tends to decrease. is there. Any method may be used for laminating the support base, the recording layer, the adhesive layer, and the light transmitting layer.

  In the above invention, the support base is preferably mainly made of polycarbonate (PC), and the thickness of the support base is preferably 0.4 mm to 1.2 mm. A more preferred thickness of the support base is 0.6 mm to 1.1 mm.

  Further, a hard coat layer may be further formed on the surface of the light transmission layer of the optical disc of the present invention, and the hard coat layer may have a pencil hardness of 3H or more in terms of pencil hardness. preferable. If the pencil hardness is less than 3H, the scratch resistance is insufficient. The hard coat layer is not particularly limited, but preferably has a crosslinked structure, more preferably a silicone crosslinked structure or an acrylic crosslinked structure. Further, the thickness of the hard coat layer is preferably 0.5 to 8.0 μm, and the thickness accuracy is preferably within ± 1.0 μm. If the thickness of the hard coat layer is less than 0.5 μm, the effect of improving the scratch resistance is low, and if it exceeds 8.0 μm, cracks occur during an environmental test.

  The method for forming such a hard coat layer is not particularly limited. For example, a hard coat precursor obtained by adding a curing catalyst to a light transmission layer film mainly formed of a thermoplastic resin, which has been prepared in advance, has a uniform thickness. , And then cured by heating or irradiating with ultraviolet light to form a laminated film, and the laminated film is bonded to the recording layer with the hard coat layer outside through an adhesive layer.

  Examples of the hard coat precursor that forms the silicone-based crosslinked structure include tetraethoxysilane, tetramethoxysilane, C1 to C12 alkyltrimethoxysilane, C1 to C12 alkyltriethoxysilane, and di (C1 to C12 alkyl) trialkylsilane. Hydrolysis condensates such as methoxysilane, di (C1 to C12 alkyl) triethoxysilane, tri (C1 to C12 alkyl) methoxysilane, and tri (C1 to C12 alkyl) ethoxysilane can be used. These silane compounds may be used alone or in combination of two or more.

  Examples of the curing catalyst added to the hard coat precursor include, for example, alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, barium hydroxide, strontium hydroxide, lithium hydroxide, magnesium hydroxide, and calcium hydroxide. , Trimethylamine, triethylamine, tri (C3-C8 alkyl) amine, dimethylamine, diethylamine, di (C3-C8 alkyl) amine, methylamine, ethylamine, (C3-C8 alkyl) amine, cyclohexamine, morpholine, trimethylammonium hydro Amine compounds such as oxide, triethylammonium hydroxide, tetramethylammonium hydroxide, hydroxyethyldimethylhydroxide, hydroxyethyldiethylhydroxide You can to have, among others potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, hydroxyethyl trimethylammonium hydroxide, hydroxyethyl triethylammonium hydroxide and the like. Among them, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, hydroxyethyltrimethylammonium hydroxide, hydroxyethyltriethylammonium hydroxide and the like are more preferable. However, these are merely examples, and the present invention is not limited to those shown here. These may be used alone or in combination of two or more. The amount of the curing catalyst to be added is not particularly limited, but can be appropriately selected in the range of 0.05% by weight to 10% by weight based on the solid content of the hard coat precursor.

  The curing temperature by heating is not particularly limited as long as it is a temperature at which the hard coat precursor can be cured, but generally, about 60 ° C. to 180 ° C. is suitable. The most preferred temperature is about 120C to 160C.

  A catalyst is used when producing the hard coat precursor. Examples of the catalyst include alkali hydroxides and amine compounds similar to the above-described curing catalysts, and further include hydrochloric acid, sulfuric acid, nitric acid, Acids such as toluenesulfonic acid, phosphoric acid, phenolsulfonic acid and polyphosphoric acid can be used. These can be used alone or in combination of two or more. Note that what is shown here is merely an example, and the present invention is not limited to these.

  The reaction temperature for producing the hard coat precursor in the present invention is not particularly limited, but a temperature of about 20C to 100C is preferable. When the temperature is lower than 20 ° C., the reaction rate decreases and productivity decreases. If the temperature exceeds 100 ° C., there is a danger because alcohol or water produced by hydrolysis or condensation boils. The reaction is preferably performed in a solution. Examples of the solvent that can be used include alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol. What is shown here is one example, and the present invention is not limited to these.

  The acrylic crosslinked structure serving as the hard coat layer in the present invention can be formed using a polymerizable material (hard coat material) containing a polymerizable compound having an acryloyl group or a methacryloyl group.

  Examples of the polymerizable compound that can be used in the hard coat material include two or more (meth) acryloyl groups such as a urethane (meth) acrylate oligomer, an epoxy (meth) acrylate oligomer, and an oligoester (meth) acrylate. Oligomer: ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate Such as alkylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and dipropylene glycol di (meth) acrylate. Dialkylene di (meth) acrylate, glycerin di (meth) acrylate, di (meth) acrylate of an adduct of alkylene oxide (ethylene oxide or propylene oxide) added to bisphenol A [for example, 2,2-bis [4- Bifunctional (meth) acrylates such as (2- (meth) acryloyloxyethoxy) phenyl] propane, 2,2-bis [4- (2- (meth) acryloyloxypropoxy) phenyl] propane, etc .; trimethylolpropane Tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, having a phosphazo group -P = N- and a (meth) acryloyl group ( Data) include multifunctional (meth) acrylates such as acrylates.

Further, in order to adjust the properties of the cured coating film, a monofunctional (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl ( _C1-20 alkyl (meth) acrylates such as meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate , 2-hydroxyethyl (meth) acrylate, hydroxyl group-containing (meth) acrylates such as 2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate A halogen-containing (meth) acrylate such as a basic nitrogen atom-containing (meth) acrylate such as a lylate, trifluoroethyl (meth) acrylate, or tetrafluoropropyl (meth) acrylate may be used in combination.

  Such a polymerizable hard coat material may be a thermosetting material containing a thermal polymerization initiator (organic peroxide such as benzoylperoxide, cumene hydroperoxide, dicumyl peroxide, etc.). In order to improve the viscosity, a photocurable type containing a photopolymerization initiator is preferable, and an ultraviolet curable type is particularly preferable.

  Examples of the compound used to initiate photopolymerization include benzoin or its derivatives (benzoin, benzoin isopropyl ether, benzoin isobutyl ether, etc.), ketones (1-hydroxycyclohexyl phenyl ketone, acetophenone and its derivatives (alkoxyacetophenone, etc.) ), Propiophenone or its derivatives (such as 2-hydroxy-2-methylpropiophenone), benzophenone or its derivatives (such as 4,4'-dimethoxybenzophenone, 4,4'-bis (4-diethylaminophenyl) ketone) , Benzyl or a derivative thereof (such as benzyl and benzyl methyl ketal), thioxanthone or a derivative thereof (2,4-diethylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone Chlorothioxanthone, etc.) can be used conventional photopolymerization initiator or a sensitizer such as these may be used alone or may be used in combination of two or more.

  The amount of the thermal polymerization initiator or the photopolymerization initiator is preferably about 0.1 to 10 parts by weight based on 100 parts by weight of the polymerizable compound.

  The hard coat material may be an organic solvent-containing coating material containing an organic solvent such as hydrocarbons, alcohols, esters, ketones, and ethers, if necessary.

  Further, the hard coat layer in the present invention preferably contains a silicone-based thermoplastic resin in an amount of 0.2 to 10.0% by weight. By containing the silicone-based thermoplastic resin, the slip property of the surface of the hard coat layer is improved, and the scratch resistance can be further improved.

  When the hard coat layer is formed on the light transmission layer to form the optical component film of the present invention, the birefringence of the two layers including the light transmission layer and the hard coat layer is a preferable value of the light transmission layer alone. Is preferably 20 nm or less, more preferably 10 nm or less, still more preferably 5 nm or less, and especially 2 nm or less in the case of a high-density DVD exceeding 20 GB. preferable.

  Further, when the hard coat layer is formed on the light transmitting layer, it is preferable that the combined film thickness, light transmittance, and the like conform to the above-described rules for the light transmitting layer alone.

  Further, on a light transmitting layer film mainly composed of a thermoplastic resin, a base layer which supports the light transmitting layer film and which is peeled off when used may be provided. In order to reduce the number of subsequent bonding steps, an adhesive layer may be provided on the film in advance, or may be provided together with the base layer. In the case of a film on which a hard coat layer is formed, the adhesive layer is formed on the surface opposite to the hard coat layer. Further, when the adhesive layer is laminated on the outermost layer, it may be protected, and a protective layer which is peeled off and removed at the time of use may be formed. Thus, the light-transmitting layer film on which the base material layer, the adhesive layer, the hard coat layer, and the protective layer can be laminated can be obtained by freely combining various layers according to the application, and has a 2 to 5 layer structure. It can be a laminated film. The “adhesive layer” refers to a layer formed by applying an adhesive or a pressure-sensitive adhesive, or laminating those films, and is capable of bonding a laminated film and a recording layer. If so, known materials can be used, and the type and forming method are not particularly limited.

  Hereinafter, a high-density DVD having a large capacity exceeding 20 GB will be described as an example of the optical disk of the present invention.

  FIG. 1 is a perspective view showing a partial structure of a high-density DVD, and FIG. 2 is a sectional view thereof. As shown in FIGS. 1 and 2, the high-density DVD 1 includes a recording layer 3 on a support base 2, and a light transmitting layer 5 is formed on the recording layer 3 via an adhesive layer 4.

  The DVD irradiates a short wavelength laser beam 6 of 405 nm from the light transmitting layer 5 side to reproduce and record signal information of the recording layer 3 through the light transmitting layer 5. The layer 5 is thin.

  As a constituent material of the DVD, a thermoplastic resin is used as the light transmitting layer 5. The thermoplastic resin is used at a temperature of 30 ° C. to 80 ° C. of the support base with respect to the amount of thermal expansion in the uniaxial direction at 30 ° C. to 80 ° C. There is no particular limitation as long as the thermal expansion ratio, which is the amount of thermal expansion in the uniaxial direction, is in the range of 0.75 to 1.25, and the support base 2 and the recording layer 3 are made of the same material as in the related art. Things can be applied.

  The support base 2 is made of, for example, a plastic substrate such as polycarbonate, and the material of the adhesive layer 4 is not particularly limited as long as the transparency is not impaired. For example, an ultraviolet curable resin, a pressure-sensitive adhesive film, or the like may be used. Can be.

  The thickness of the support base 2 may be in the range of 0.4 mm to 1.2 mm, and the thickness of the recording layer 3 and the adhesive layer 4 may be in the range of 30 μm to 250 μm. 4 has a thickness of 30 μm to 150 μm.

  In addition, as a method of laminating each of the above-described support base 2, recording layer 3, adhesive layer 4, and light transmission layer 5, any method may be used.

  Next, optical disks were manufactured according to the following examples, and various characteristics were examined.

Specifically, according to Examples 1 to 10 and Comparative Examples 1 to 4, a film for a light transmitting layer in which a resin material is changed, and a laminated film in which a hard coat layer is formed on each surface thereof In addition to the evaluation of the characteristics of the optical disk, an optical disk was manufactured using each light transmitting layer film and each laminated film, and the characteristics of the optical disk were evaluated. Table 1 summarizes the materials used in the examples and comparative examples. In addition, structural formula 35, structural formula 36, and structural formula 37 in Table 1 correspond to Chemical formula 35, Chemical formula 36, and Chemical formula 37, respectively.

[Example 1]
In this example, first, a vinyl polymer (acrylic resin) containing a vinyl polymer A having a proton donating atom group and a vinyl polymer B having a proton accepting atom group was produced, and the vinyl polymer was produced from the vinyl polymer. A film was formed, and an optical disk using this film was produced.

<Production of vinyl polymer>
[Production of vinyl polymer A having proton-donating atomic group]
200 g of acetone was charged into a 500 mL autoclave as a polymerization solvent, and 56.1 g (29 mol%) of tricyclo [5.2.1.0 ^2,6 ] dec-8-yl methacrylate (TCDMA) and butyl acrylate (BA 73.1 g (65 mol%) and 3.8 g (6 mol%) of acrylic acid (AA) were weighed, and 0.4 g of lauroyl peroxide as a polymerization initiator was added to and dissolved in the monomer mixture. Was added to the flask. Thereafter, nitrogen gas was passed at room temperature (25 ° C.) for about 1 hour to replace dissolved oxygen, and then the temperature was raised to 60 ° C. under a nitrogen stream. The same temperature was maintained for about 18 hours to obtain an acetone solution of the vinyl polymer A having a proton donating atomic group. At this time, the polymerization rate was 98% or more.

[Production of Vinyl Polymer B Having Proton Accepting Group]
200 g of acetone was charged into a 500 mL autoclave as a polymerization solvent, and 88.8 g (81.6 mol%) of methyl methacrylate (MMA) and tricyclo [5.2.1.0 ^2,6 ] deca-8-yl methacrylate were used. (TCDMA) 37.1 g (15.5 mol%) and 2,2,6,6-tetramethylpiperidyl methacrylate 7.1 g (2.9 mol%) were weighed, and azobisisobutyi was used as a polymerization initiator. After adding and dissolving 0.4 g of lonitrile to the monomer mixture, the mixture was added to the flask. Thereafter, nitrogen gas was passed at room temperature (25 ° C.) for about 1 hour to replace dissolved oxygen, and then the temperature was raised to 60 ° C. under a nitrogen stream. The same temperature was maintained for 18 hours to obtain an acetone solution of vinyl polymer B. At this time, the polymerization rate was 98% or more.

<Manufacture of light transmission layer film>
The resulting acetone solution of the vinyl polymer A having a proton donating group and the acetone solution of the vinyl polymer B having a proton accepting group were mixed in a weight ratio of 4: 6 to form a vinyl polymer mixture. Obtained. Thereafter, 0.1% each of an antioxidant represented by abbreviated names AO-50 and HP-10 was added to the vinyl polymer mixture to dissolve completely, and then the solution was applied on a glass plate. Thereafter, after heating and drying at 100 ° C. for 10 minutes, the solvent was removed by heating and drying at 150 ° C. for 15 minutes to produce a light transmitting layer film having a thickness of about 100 μm. The prepared film was used as an evaluation sample, and the thermal expansion amount, the thermal expansion ratio, the light transmittance, the birefringence, the film thickness, and the film thickness accuracy were evaluated by the following measurement methods. The evaluation results are shown in Table 2 below.

[Thermal expansion amount, thermal expansion ratio]
A film (4 mm × 20 mm) having a size (4 mm × 20 mm) was prepared from each material forming the light transmitting layer as an evaluation test piece, and the amount of thermal expansion in the uniaxial direction when the temperature was increased from 30 ° C. to 80 ° C. was measured. For the measurement, SSC / 5200 manufactured by Seiko Instruments was used, the measurement conditions were a heating rate of 2 ° C./min, and the measurement mode was a tensile mode. Further, an evaluation test piece having a size (4 mm × 20 mm) was prepared from a support base formed of polycarbonate, and the amount of thermal expansion was measured in the same manner. The method of measuring the amount of thermal expansion is as follows. At 30 ° C., an iron jig is attached to both sides of the test piece of the above size with a gap of 10 mm in the longitudinal direction as a gap, and the temperature is raised under the above measurement conditions. The amount of expansion was measured as the amount of expansion and expressed in μm.

  The thermal expansion ratio of the film of the support base to the light transmission layer was calculated for the measured amount of thermal expansion between the film of the light transmission layer and the support base.

[Light transmittance (%)]
The light transmittance was measured at room temperature (25 ° C.) at a wavelength of 405 nm using a spectrophotometer. As a measuring instrument, V-570 manufactured by JASCO was used.

[Birefringence (nm)]
The birefringence was measured using an ellipsometer AEP-100 manufactured by Shimadzu Corporation.

[Film thickness (μm), film thickness accuracy (μm)]
The film thickness and film thickness accuracy of the film were measured using a laser focus displacement meter (manufactured by Keyence, LT-8100) for a square film having a size of 12 cm × 12 cm.

  The four sides of the square film were designated as straight line A, straight line B, straight line C, and straight line D, respectively, the side facing straight line A was taken as straight line C, and the side facing straight line B was taken as straight line D. Three parallel straight lines spaced 3 cm from the straight line A to the straight line C are referred to as a straight line A1, a straight line A2, and a straight line A3, respectively. These three parallel straight lines (A1, straight line A2, straight line A3) and straight line A And a total of five straight lines C, the thickness of the film at each point on the straight line was measured by the following procedure. First, a point 1 cm inside the square from one end of the straight line A is used as a reference point. For each point spaced 1 mm from the reference point toward the other end of the straight line A, from the other end to a point 1 cm inside the square. The film thickness of the film was measured at a total of 101 points over a length of 10 cm. Next, using the same method as that for the straight line A, the film thickness at each point of the straight line A1, the straight line A2, the straight line A3, and the straight line C was measured. It was measured. Further, similarly to the above-described straight lines from the straight line A to the straight line C, a total of 505 straight lines (straight line B, straight line B1, straight line B2, straight line B3, and straight line D) from the straight line B to the straight line D are obtained. The film thickness was measured for the points. Finally, the average value of the film thickness of a total of 1010 pieces in the square film measured by the method described above was defined as the film thickness.

<Production of optical disk>
An adhesive film (Sekisui Chemical: 5511) was laminated on a polycarbonate support base having a diameter of 12 cm, and the light transmission layer film produced above was laminated on the adhesive film to produce an optical disk. With respect to the difference in refractive index between the adhesive layer and the light transmitting layer and the produced optical disk, the warpage of the optical disk was evaluated by the following measurement method. The results are shown in Table 2 below.

[Refractive index difference]
The refractive index of each of the light transmitting layer and the adhesive layer was measured using an Abbe refractometer, and the difference was determined.

[Optical disk warpage]
The amount of warpage of the produced optical disc after leaving it to stand in a thermo-hygrostat at a temperature of 80 ° C. and a humidity of 85% for 100 hours was measured. The amount of warpage was measured using a stereoscopic microscope to measure the distance at which the end of the 12-cm-diameter disk fluctuated from the horizontal plane, and calculated the angle from the measured fluctuation distance using a trigonometric function. The calculated angle was used as the amount of disk warpage. .

[Example 2]
In this example, a vinyl polymer A and a vinyl polymer B manufactured by the same method as in Example 1 were used, and the mixing ratio of both vinyl polymers was changed. The light transmitting layer film was produced by the procedure described above. After that, an optical disk was produced using the produced film in the same procedure as in Example 1. For the light transmission layer film and the optical disk, various characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

  With respect to the above mixing ratio, specifically, the acetone solution of the obtained vinyl polymer A and the acetone solution of the vinyl polymer B are mixed at a weight ratio of 3: 7, and then completely dissolved. Then, the solution was applied on a glass plate, and then heated and dried at 100 ° C. for 10 minutes, and further heated and dried at 150 ° C. for 15 minutes to remove the solvent, thereby producing a film having a thickness of about 100 μm. And

[Example 3]
Example 1 In this example, the procedure of Example 1 was repeated except that a light-transmitting layer film made of one kind of a single vinyl polymer produced by the following method was used without mixing two kinds of vinyl polymers. An optical disk was produced in the same manner as described above. For the light transmission layer film and the optical disk, various characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

<Production of vinyl polymer>
After weighing 98 g (99 mol%) of methyl methacrylate (MMA) and 2 g (1 mol%) of ethylene dimethacrylate (EDMA), 0.3 g of lauroyl peroxide as a polymerization initiator was added to the monomer mixture and dissolved. At room temperature (25 ° C.), nitrogen gas was passed for about 1 hour to dissolve dissolved oxygen, and the mixture was sealed between stainless steel plates provided with a 100 μm gap. This was left in a thermostat at 60 ° C. for about 18 hours to carry out a polymerization reaction. At this time, the polymerization rate was 99% or more. The stainless plate was removed to obtain a film having a thickness of 100 μm.

[Example 4]
In this example, a vinyl polymer A and a vinyl polymer B manufactured by the same method as in Example 1 were used, and the mixing ratio of both vinyl polymers was changed. A film was produced according to the procedure described above. After that, an optical disk was produced using the produced film in the same procedure as in Example 1. For the light transmission layer film and the optical disk, various characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

  With respect to the mixing ratio, specifically, the acetone solution of the obtained vinyl polymer A and the acetone solution of the vinyl polymer B were mixed at a weight ratio of 5: 5, and then completely dissolved. Then, after applying the solution on a glass plate, heat drying at 100 ° C. for 10 minutes, and further heat drying at 150 ° C. for 15 minutes to remove the solvent, thereby producing a light transmitting layer film having a thickness of about 100 μm. This was used as an evaluation sample.

[Example 5]
In this example, a vinyl polymer A and a vinyl polymer B manufactured by the same method as in Example 1 were used, and the mixing ratio of both vinyl polymers was changed. A film was produced according to the procedure described above. After that, an optical disk was produced using the produced film in the same procedure as in Example 1. For the light transmission layer film and the optical disk, various characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

  Regarding the mixing ratio, specifically, the acetone solution of the obtained vinyl polymer A and the acetone solution of the acetone solution of the vinyl polymer B are mixed at a weight ratio of 2: 8, and then completely dissolved. Then, after applying the solution on a glass plate, heat drying at 100 ° C. for 10 minutes, and further heat drying at 150 ° C. for 15 minutes to remove the solvent, thereby producing a light transmitting layer film having a thickness of about 100 μm. This was used as an evaluation sample.

[Comparative Example 1]
In this comparative example, a light transmitting layer film and an optical disk were produced in the same manner as in Example 1, except that the vinyl polymer A having a proton donating atomic group was produced by the following method. For the light transmission layer film and the optical disk, various characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Vinyl polymer A having proton-donating atomic group]
200 g of acetone was charged into a 500 mL autoclave as a polymerization solvent, and 58.0 g (31 mol%) of tricyclo [5.2.1.0 ^2,6 ] dec-8-yl methacrylate (TCDMA) and butyl acrylate (BA 75.0 g (69 mol%) was weighed, and 0.4 g of lauroyl peroxide as a polymerization initiator was added to and dissolved in the monomer mixture, and the mixture was added to the flask. Thereafter, the dissolved oxygen was replaced at room temperature (25 ° C.) by passing nitrogen gas for about 1 hour, and the temperature was raised to 60 ° C. under a nitrogen stream. The same temperature was maintained for about 18 hours to obtain an acetone solution of the vinyl polymer A having a proton donating atomic group. At this time, the polymerization rate was 99% or more.

[Comparative Example 2]
In this comparative example, the same procedure as in Example 1 was carried out except that the light-transmitting layer film produced from one kind of a single vinyl polymer produced by the following method was used without mixing the two kinds of vinyl polymers. An optical disk was produced in the same manner as described above. For the light transmission layer film and the optical disk, various characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

<Production of vinyl polymer>
200 g of acetone was charged into a 500 mL autoclave as a polymerization solvent, and 76.2 g (65 mol%) of methyl methacrylate (MMA), 37.5 g (25 mol%) of butyl acrylate (BA), and 19.2 g (10%) of cyclohexylmaleimide were added. Mol%), 0.4 g of lauroyl peroxide as a polymerization initiator was added to and dissolved in the monomer mixture, and the mixture was added to the flask. Thereafter, nitrogen gas was passed at room temperature for about 1 hour to replace dissolved oxygen, and then the temperature was raised to 60 ° C. under a nitrogen stream. The temperature was maintained for about 18 hours to obtain an acetone solution of the vinyl polymer. At this time, the polymerization rate was 99% or more.

<Production of film>
After the above solution was applied on a glass plate, it was dried by heating at 100 ° C. for 10 minutes, and further dried by heating at 150 ° C. for 15 minutes to remove the solvent, thereby producing a film of about 100 μm, which was used as an evaluation sample.

  As shown in Table 2, the acrylic polymer forming the light transmitting layer of Comparative Example 1 did not show a film-forming ability and could not be measured for the amount of thermal expansion. Although the thermal expansion ratio of the support base to the layer was as small as 0.72 and the amount of warpage was high, the thermal expansion ratios of Examples 1 to 5 were 0.75 to 1. 25, the warpage of the optical disk could be reduced.

[Example 6]
In this example, first, a vinyl polymer (acrylic resin) containing a vinyl polymer A having a proton donating atom group and a vinyl polymer B having a proton accepting atom group was produced, and the vinyl polymer was produced from the vinyl polymer. A film was formed, and a hard coat precursor was coated and laminated on the film, and cured by heating. Then, an optical disk using the laminated film was produced.

<Production of vinyl polymer>
[Production of vinyl polymer A having proton-donating atomic group]
1279 g of acetone as a polymerization solvent was charged into a 4 liter stainless steel autoclave having a pressure resistance of 2.3 kg / cm ² G, and 449 g of tricyclo [5.2.1.0 ^2,6 ] dec-8-yl methacrylate (TCDMA) was added. (29 mol%), 585 g (65 mol%) of butyl acrylate (BA) and 30 g (6 mol%) of acrylic acid (AA) were weighed, and 3.2 g of lauroyl peroxide was added to the monomer mixture as a polymerization initiator. After dissolution, the mixture was added to the flask. Thereafter, nitrogen gas was passed at room temperature (25 ° C.) for about 1 hour to replace dissolved oxygen, and then the temperature was raised to 60 ° C. under a nitrogen stream. The same temperature was maintained for about 18 hours to obtain an acetone solution of the vinyl polymer A having a proton donating atomic group. At this time, the polymerization rate was 98% or more.

[Production of Vinyl Polymer B Having Proton Accepting Group]
1279 g of acetone was charged as a polymerization solvent into a 4 liter stainless steel autoclave having a pressure resistance of 2.3 kg / cm ² G, and 710 g (81.6 mol%) of methyl methacrylate (MMA) and tricyclomethacrylate [5.2.1] were added. .0 ^2,6] dec-8-yl (TCDMA) 297 g (15.5 mol%), 2,2,6,6, - and weighed tetramethylpiperidyl methacrylate 57 g (2.9 mol%), polymerized After adding and dissolving 3.2 g of azobisisobutyronitrile as an initiator to the monomer mixture, the mixture was added to the flask. Thereafter, nitrogen gas was passed at room temperature (25 ° C.) for about 1 hour to replace dissolved oxygen, and then the temperature was raised to 60 ° C. under a nitrogen stream. The same temperature was maintained for 18 hours to obtain an acetone solution of vinyl polymer B. At this time, the polymerization rate was 98% or more.

<Manufacture of light transmission layer film>
The resulting acetone solution of the vinyl polymer A having a proton donating group and the acetone solution of the vinyl polymer B having a proton accepting group were mixed in a weight ratio of 4: 6 to form a vinyl polymer mixture. Obtained. Thereafter, 0.1% of an antioxidant represented by abbreviation AO-50 and an abbreviation HP-10 were added to the vinyl polymer mixture in an amount of 0.1% each and completely dissolved, and then this solution was applied to a comma coater head made by Hirano Techseed. Using a machine, PET of Cosmoshine A-4100 (manufactured by Toyobo Co., Ltd.) was used as a base material layer, coating was performed at a speed of 3 m / min, and a continuous drying path at 50 ° C. for 3 minutes at 140 ° C. For 3 minutes to form a light transmitting layer film. At this time, the film thickness was 100 μm. The prepared film was used as an evaluation sample, and by the same measurement method as described above, the thermal expansion amount, thermal expansion ratio, light transmittance, birefringence, film thickness, and film thickness accuracy of the light transmission layer film of the present example were as described above. Each was evaluated by the same measurement method. The evaluation results are shown in Table 3 below.

<Manufacture of laminated film>
3.3% by weight of a 15% aqueous solution of tetramethylammonium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the solid content of the hard coat precursor (x-12-2206), and the -coat precursor solution was added. It was adjusted. This solution was coated on the light transmitting layer film using a coating machine of a comma coater head manufactured by Hirano Techseed, and continuously passed through a drying path at 50 ° C. for 3 minutes and a drying path at 150 ° C. for 3 minutes to form a laminated film. Formed. At this time, the thickness of the laminated film is 105 μm, and the thickness of the light transmission layer film is 100 μm, so that the thickness of the hard coat layer is 5 μm. The film thickness, thickness accuracy, light transmittance, and birefringence of the laminated film of this example were measured by the same measuring methods as described above, and the pencil hardness and adhesion of the hard coat layer of the laminated film were measured by the following methods. The evaluation results are shown in Table 3 below.

[Pencil hardness of hard coat]
The pencil hardness of the hard coat was determined by adding a 15% aqueous solution of tetramethylammonium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) in an amount of 3.3% by weight to the solid content of the hard coat precursor, and applying it to a glass plate. After that, the coating was heated at 150 ° C. for 3 minutes immediately after heating at 50 ° C. for 3 minutes to prepare a hard coat, and its pencil hardness was measured in accordance with JIS K5400.

[Adhesion of hard coat]
10 cuts of 1 cm or more were cut in a grid pattern at intervals of 1 mm from the hard coat surface of the laminated film, and the number of peeled pieces was immediately divided by the number of squares when a cellophane tape was stuck thereon and then immediately peeled off. Those were taken as a measure of adhesion.

<Production of optical disk>
An adhesive film (Sekisui Chemical product name: 5511) was laminated on a polycarbonate support base having a diameter of 12 cm, and a laminated film produced on the adhesive film was laminated to produce an optical disc. The difference in the refractive index between the adhesive layer and the light transmitting layer and the amount of warpage of the produced optical disk were measured by the same measuring method as described above, and the scratch resistance was measured by the following measuring method. The results are shown in Table 3 below.

[Scratch resistance of optical disk]
The scratch resistance of the optical disk was measured using a wear tester at a load of 250 g, a worn wheel CSF-1, and the number of rotations was 100. The haze after the test was used as a measure of the scratch resistance. The haze (%) was measured at room temperature using a haze meter (HGM-2, manufactured by Suga Test Instruments Co., Ltd.).

[Example 7]
In this example, a vinyl polymer A and a vinyl polymer B produced in the same manner as in Example 6 were used, and the same as Example 1 except that the mixing ratio of both vinyl polymers was changed. The light transmitting layer film was produced by the procedure described above. Thereafter, a hard coat layer was formed on the produced light transmitting layer film in the same procedure as in Example 6, to produce a laminated film, and an optical disc was produced using the laminated film.

  With respect to the above mixing ratio, specifically, the acetone solution of the obtained vinyl polymer A and the acetone solution of the vinyl polymer B are mixed at a weight ratio of 3: 7, and then completely dissolved. The solution was applied at a rate of 3 m / min using a Cosmoshine A-4100 (manufactured by Toyobo Co., Ltd.) PET as a base material layer using a Hirano Techseed comma coater head coater. The light-transmitting layer film was formed by passing through a drying path at 50 ° C. for 3 minutes and a drying path at 140 ° C. for 3 minutes. At this time, the thickness of the light transmitting layer film was 100 μm.

  For the light transmitting layer film, the laminated film, and the optical disk of this example, various characteristics were evaluated in the same manner as in Example 6, and the results are shown in Table 3.

[Example 8]
In this example, two kinds of vinyl polymers were not mixed, and a light transmitting layer film made of one kind of a single vinyl polymer produced by the method shown below was produced by the method shown below. An optical disk was manufactured in the same manner as in Example 6, except that the laminated film thus obtained was used. For the light transmitting layer film, the laminated film, and the optical disk of this example, various characteristics were evaluated in the same manner as in Example 6, and the results are shown in Table 3.

<Production of vinyl polymer>
After 98 g (99 mol%) of methyl methacrylate (MMA) and 2 g (1 mol%) of ethylene dimethacrylate (EDMA) were weighed, 0.3 g of lauroyl peroxide as a polymerization initiator was added to the monomer mixture and dissolved. At room temperature (25 ° C.), nitrogen gas was passed for about 1 hour to dissolve dissolved oxygen, and the mixture was sealed between stainless steel plates provided with a 100 μm gap. This was left in a thermostat at 60 ° C. for about 18 hours to carry out a polymerization reaction. At this time, the polymerization rate was 99% or more. The stainless steel plate was removed to obtain a light transmitting layer film having a thickness of 100 μm.

<Manufacture of laminated film>
3.3% by weight of a 15% aqueous solution of tetramethylammonium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the solid content of the hard coat precursor (x-12-2206) to obtain a hard coat precursor solution. It was adjusted. This solution was applied on the light transmitting layer using a hand coater, dried at 50 ° C. for 10 minutes, and then heated at 150 ° C. for 5 minutes to obtain a laminated film. At this time, the thickness of the hard coat layer was about 2 μm.

[Example 9]
In this example, a vinyl polymer A and a vinyl polymer B produced in the same manner as in Example 6 were used, and the same as Example 1 except that the mixing ratio of both vinyl polymers was changed. The light transmitting layer film was produced by the procedure described above. Thereafter, a hard coat layer was formed on the produced light transmitting layer film in the same procedure as in Example 6, to obtain a laminated film. The thickness of the hard coat layer was about 2 μm. Thereafter, an optical disk was manufactured in the same procedure as in Example 6.

  With respect to the mixing ratio, specifically, the acetone solution of the obtained vinyl polymer A and the acetone solution of the vinyl polymer B were mixed at a weight ratio of 5: 5, and then completely dissolved. The solution was applied at a rate of 3 m / min using a Cosmoshine A-4100 (manufactured by Toyobo Co., Ltd.) PET as a base material layer using a Hirano Techseed comma coater head coater. The light-transmitting layer film was formed by passing through a drying path at 50 ° C. for 3 minutes and a drying path at 140 ° C. for 3 minutes. At this time, the thickness of the light transmitting layer film was 100 μm.

  For the light transmitting layer film, the laminated film, and the optical disk of this example, various characteristics were evaluated in the same manner as in Example 6, and the results are shown in Table 3.

[Example 10]
In this example, the same procedure as in Example 6 was carried out except that the vinyl polymer A and the vinyl polymer B produced by the same method as in Example 6 were used, and the mixing ratio of both vinyl polymers was changed. The light transmitting layer film was produced by the procedure described above. Thereafter, a hard coat layer was applied on the produced light transmitting layer film in the same procedure as in Example 6, to obtain a laminated film. The thickness of the hard coat layer was about 2 μm. Thereafter, an optical disk was manufactured in the same procedure as in Example 6.

  Regarding the mixing ratio, specifically, the acetone solution of the obtained vinyl polymer A and the acetone solution of the acetone solution of the vinyl polymer B are mixed at a weight ratio of 2: 8, and then completely dissolved. The solution was applied at a rate of 3 m / min using a Cosmoshine A-4100 (manufactured by Toyobo Co., Ltd.) PET as a base material layer using a Hirano Techseed comma coater head coater. The light-transmitting layer was formed by passing through a drying path at 50 ° C. for 3 minutes and a drying path at 140 ° C. for 3 minutes. At this time, the thickness of the light transmitting layer was 100 μm.

  For the light transmitting layer film, the laminated film, and the optical disk of this example, various characteristics were evaluated in the same manner as in Example 6, and the results are shown in Table 3.

[Comparative Example 3]
In this comparative example, light transmission was performed using the same method as in Example 6, except that the vinyl polymer A having a proton donating atomic group was produced by the following method, and that the hard coat layer was not formed. A layer film and an optical disk were produced. For the light transmitting layer film and the optical disk of this example, various property evaluations were performed in the same manner as in Example 6, and the results are shown in Table 3.

[Vinyl polymer A having proton-donating atomic group]
To a 4 liter stainless steel autoclave having a pressure resistance of 2.3 kg / cm ² G, 1279 g of acetone was charged as a polymerization solvent, and 464 g of tricyclo [5.2.1.0 ^2,6 ] dec-8-yl methacrylate (TCDMA) was added. (31 mol%) and 600 g (69 mol%) of butyl acrylate (BA) were weighed, and 3.2 g of lauroyl peroxide as a polymerization initiator was added to and dissolved in the monomer mixture, and the mixture was added to the flask. did. Thereafter, the dissolved oxygen was replaced at room temperature (25 ° C.) by passing nitrogen gas for about 1 hour, and the temperature was raised to 60 ° C. under a nitrogen stream. The same temperature was maintained for about 18 hours to obtain an acetone solution of the vinyl polymer A having a proton donating atomic group. At this time, the polymerization rate was 99% or more.

[Comparative Example 4]
In this example, a hard coat layer of a laminated film was used without mixing two kinds of vinyl polymers and using a light transmitting layer film made of one kind of a single vinyl polymer produced by the following method. An optical disk was manufactured in the same manner as in Example 6, except that the film thickness of was adjusted to about 0.5 μm. For the light transmitting layer film, the laminated film, and the optical disk of this example, various characteristics were evaluated in the same manner as in Example 6, and the results are shown in Table 3.

<Production of vinyl polymer>
1279 g of acetone was charged as a polymerization solvent into a 4 liter stainless steel autoclave having a pressure resistance of 2.3 kg / cm ² G, and 610 g (65 mol%) of methyl methacrylate (MMA) and 300 g (25 mol%) of butyl acrylate (BA) were added. ) And 154 g (10 mol%) of cyclohexylmaleimide were weighed, and 3.2 g of lauroyl peroxide as a polymerization initiator was added to and dissolved in the monomer mixture, and the mixture was added to the flask. Thereafter, nitrogen gas was passed at 25 ° C. for about 1 hour to replace dissolved oxygen, and the temperature was raised to 60 ° C. under a nitrogen stream. The temperature was maintained for about 18 hours to obtain an acetone solution of the vinyl polymer. At this time, the polymerization rate was 99% or more.

<Production of film>
After the above solution was applied on a glass plate, it was dried by heating at 100 ° C. for 10 minutes, and further dried by heating at 150 ° C. for 15 minutes to remove the solvent.

  As shown in Table 3, the acrylic polymer forming the light transmitting layer of Comparative Example 3 did not show a film-forming ability and could not be measured for the amount of thermal expansion. Although the thermal expansion ratio of the support base to the layer was as small as 0.72 and the amount of warpage was high, in Examples 6 to 10, the thermal expansion ratio was 0.75 to 1. 25, the warpage of the optical disk could be reduced.

  When the hard coat of Comparative Example 3 was not laminated, and when the thickness of the hard coat of Comparative Example 4 was too thin, the abrasion resistance was low, whereas in Examples 6 to 10, the abrasion resistance was low. It can be seen that the properties have been improved.

FIG. 1 is a perspective view showing a partial structure of a high-density DVD according to an embodiment of the present invention. FIG. 2 is an exemplary sectional view showing the structure of a part of the high-density DVD shown in FIG. 1; FIG. 2 is a perspective view in which a part of the DVD is enlarged in order to schematically explain the structure of the DVD in a conventional example. FIG. 4 is a sectional view of the DVD shown in FIG. 3.

Explanation of reference numerals

1 High density DVD
2 support base 3 recording layer 4 adhesive layer 5 light transmitting layer 6 laser beam

Claims (16)

  An optical disc in which a recording layer, an adhesive layer, and a light transmission layer are sequentially laminated on at least one surface of a support base, wherein the support base has a thermal expansion amount in a uniaxial direction of 30 ° C. to 80 ° C. of the light transmission layer. An optical disk having a thermal expansion ratio, which is a thermal expansion amount in a uniaxial direction at 30 ° C. to 80 ° C., within a range of 0.75 to 1.25, and wherein the light transmitting layer is mainly made of a thermoplastic resin; .   The optical disc according to claim 1, wherein a hard coat layer having a pencil hardness of 3H or more is formed on the light transmitting layer.   3. The optical disk according to claim 2, wherein the thickness of the hard coat layer is 0.5 to 8 [mu] m, and the thickness accuracy is within ± 1.0 [mu] m.   The optical disk according to claim 2, wherein the hard coat layer is a crosslinked structure.   The optical disk according to any one of claims 2 to 4, wherein the hard coat layer is a silicone-based crosslinked structure or an acrylic-based crosslinked structure.   The optical disk according to any one of claims 2 to 5, wherein the hard coat layer contains 0.2 to 10.0% by weight of a silicone-based thermoplastic resin.   The optical disc according to any one of claims 1 to 6, wherein the light transmission layer has a birefringence of 20 nm or less and a thickness of 15 m to 250 m.   The optical disc according to any one of claims 1 to 7, wherein the light transmission layer has a light transmittance at a wavelength of 405 nm of 87% or more.   The thermoplastic resin of the light transmitting layer is a vinyl copolymer containing at least one kind of proton donating group and at least one kind of proton accepting group. 9. The optical disk according to any one of items 8 to 8.   The thermoplastic resin of the light transmitting layer is a vinyl-based copolymer, and the vinyl-based copolymer is a vinyl-based polymer A having at least one proton-donating atomic group and at least one proton-accepting group. 9. A mixture of a vinyl polymer B having an atomic group and pseudo-crosslinks formed by an intermolecular hydrogen bond in the mixture. Optical disk.   The vinyl polymer A is obtained by polymerizing a monomer mixture containing a vinyl monomer having one or more functional groups selected from carboxyl groups, hydroxyl groups and phenolic hydroxyl groups in the molecule. The vinyl polymer B is a polymer obtained by polymerizing a monomer mixture containing a vinyl monomer having a nitrogen atom in the molecule, and the vinyl polymer The optical disc according to claim 10, wherein one of the coalesced A and the vinyl polymer B has a glass transition temperature of 25 ° C or higher, and the other has a glass transition temperature of less than 25 ° C.   12. The optical disk according to claim 1, wherein the thermoplastic resin is an acrylic resin.   The thermoplastic resin of the light transmitting layer contains at least one compound selected from phenolic antioxidants, phosphite antioxidants, thioether antioxidants and light stabilizers. The optical disc according to any one of claims 1 to 12, wherein:   14. The optical disc according to claim 1, wherein a difference in refractive index between the light transmitting layer and the adhesive layer is 0.1 or less.   15. The optical disk according to claim 1, wherein the support base is mainly made of polycarbonate.   16. The optical disk according to claim 1, wherein the thickness of the support base is 0.4 mm to 1.2 mm.

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