JPH0278034A - Optical recording carrier - Google Patents

Abstract

PURPOSE:To realize continuous 2P (photopolymerization) molding of highly reliable optical recording carrier with good productivity by using specific UV- curing resin composition as the 2P material. CONSTITUTION:The optical recording carrier consisting of a setting-type resin and having preformat signals of a setting-type resin and having preformat signals and guide grooves is formed on a transparent disk by 2P (photopolymerization) method. The setting-type resin used here is an UV-curing resin composition consisting of a prepolymer component (A) comprising a diacrylate of carbonate diol of 500 - 5,000 mean molecular weight, an acrylate component (B) comprising a compound expressed by structural formula (I), and an initiator of photopolymerization (C). The proportion of each component is determined to satisfy that the diacrylate of carbonate diol (A) is at least 10wt.%, the acrylate (B) of structural formula (I) is at least 60wt.% and the initiator of photopolymerization (C) is 0.5 - 5wt.%. Thus, continuous 2P molding can be realized by this method and highly reliable optical recording medium can be obtained with good productivity.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical record carrier for an optical recording medium that can be read only or recorded/played/erased by a light beam.
For details, see 2P () Odo Volimerization: Pho
The present invention relates to an optical recording carrier using an ultraviolet curable resin composition as a 2P material in a polymerization method.

[Prior Art] Conventionally, glass, acrylic resin, polycarbonate resin, etc. have been used as substrate materials for optical recording media. In order to perform high-density recording on an optical recording medium, it is necessary to form optical guide grooves on the substrate thereof, and two methods are conventionally known for this purpose. Another method is to perform injection molding using a mold in which unevenness corresponding to the shape of the guide groove is carved, thereby transferring the guide groove at the same time as molding the substrate.

Another method is to first apply an ultraviolet curable resin or the like on a mold in which unevenness corresponding to the shape of the guide groove has been carved, and then place the substrate on this resin. 2. By irradiating the resin, the resin is cured and the resin is fixed to the substrate to form a guide groove made of the hardening resin.
This method is called the P method.

The former method is excellent in mass production, but it has the disadvantage of poor transferability of the guide groove shape, and the problem is that only plastics, such as acrylic resin or polycarbonate resin, can be used as the substrate material. . That is, in a recording medium using a plastic substrate, since the plastic substrate has air permeability, the recording layer is corroded by moisture, oxygen, etc., and its recording characteristics gradually deteriorate. Therefore, if this method, in which only plastic is used as the substrate material, is adopted, a problem arises in that it is not possible to manufacture a recording medium that can maintain its recording characteristics for a long period of time.

On the other hand, the latter method not only has good transferability of the guide groove shape, but also allows the use of glass instead of plastic as the substrate material. Therefore, by using a glass substrate provided with guide grooves by this method, a recording medium that can maintain high reliability for a long period of time can be manufactured.

The 2P materials used in the 22 method include heat resistance,
Conditions such as high moisture resistance and short curing time are required.
A resin composition as described in JP-A-88503 and the like is used.

[Problems to be Solved by the Invention] However, the resin compositions used as 2P materials as described above still have problems with accuracy, heat resistance, etc., and a more reliable ultraviolet curable resin composition is desired. ing. Specifically, conventional problems include the following.

The first problem is that the shape of the groove-shaped edges formed by the 2P method does not have sufficient heat resistance even at high temperatures. When environmental durability tests were conducted on recording media, there was a problem in that the C/N ratio decreased.

The second problem is that the preformat signals and guide grooves made of curable resin formed by the 2P method do not have sufficient moisture resistance. When conducting an environmental durability test of the medium, there was a problem that the recording layer deteriorated and corroded due to water absorption and permeation of the curable resin.

The third problem is that the preformat signal and guide grooves made of curable resin formed by the 2P method do not have sufficient hardness, which causes the recording layer, recording layer, and protective layer to form on the optical record carrier. When laminated by sputtering or vacuum deposition, there is a problem that the preformat signal and guide grooves made of curable resin will peel off from the substrate due to the stress of these layers. Even if the film is formed using
There was a problem that peeling occurred between the P layers.

The fourth problem is that the preformat signals and guide grooves made of a curable resin formed by the 2P method have a large amount of volatile components when heated, so the recording layer is not formed on the optical record carrier.
In optical recording media provided with an amorphous magnetic recording layer such as dTb, GdTbFe, GdTbFeCo, etc., there is a problem in that the recording sensitivity changes due to low molecular weight substances that volatilize upon heating.

The fifth problem is that when cured by the 2P method, the resin preformat signals and guide grooves undergo large curing shrinkage, so when an environmental durability test is performed, wrinkles occur in the preformat signals and guide grooves. There was a problem.

The sixth problem is that the preformat signals and guide grooves made of a hardening resin do not peel well from the stamper, which is a metal mold.

An object of the present invention is to provide an optical recording carrier that solves the above-mentioned conventional problems by using a specific ultraviolet curable resin composition as a 2P material.

That is, even when an optical recording medium having a recording layer provided on the optical recording carrier of the present invention is subjected to an environmental durability test, the C/N does not decrease, and the recording layer does not deteriorate or corrode due to water absorption or permeation. No peeling occurs between the substrate and the 2P layer, no wrinkles occur in the preformat signal or guide groove, and no amorphous magnetic recording layer is used as a recording layer on the optical recording carrier. In an optical recording medium provided with
To provide an optical record carrier in which recording sensitivity hardly changes due to low molecular weight substances that volatilize when heated, and furthermore, a preformat signal and guide groove made of a curable resin can be easily peeled from a stamper which is a mold. It is in.

[Means for Solving the Problems] and [Operations] In other words, the present invention provides an optical record carrier having preformat signals and guide grooves made of a curable resin formed by the 2P method on a transparent disc, The curable resin is (A)
Average molecular i 500-5000 as prepolymer component
(B) a compound represented by the following structural formula (I) as an acrylic acid ester component; and (C) an ultraviolet curable resin composition containing a photopolymerization initiator. It is an optical record carrier.

(I) The diacrylate of carbonate diol (average molecular weight 500 to 5,000) used in the present invention (hereinafter referred to as carbonate diol diacrylate) is obtained by reacting carbonate diol and acrylic acid. A specific method for producing carbonate diol is known. Preferably 1.0 to 2.0 mol of acrylic acid, particularly preferably 1.0 to 1.5 mol, and an esterification catalyst (e.g. p-toluenesulfonic acid, sulfuric acid, metasulfonic acid) per 0.5 mol of carbonate diol. etc.) and a polymerization inhibitor (for example, methoquinone, phenothiazine, hydroquinone, etc.) are each preferably added in an amount of 0.01 to 5% by weight based on acrylic acid, preferably 70'C to 13% by weight.
After heating and dehydrating at 0°C, wash with alkali and water.

By removing low boilers 4, carbonate diol diacrylate can be obtained.

Carbonate diol as a raw material for producing carbonate diacrylate is a carbonate derivative, such as diaryl carbonate such as diphenyl carbonate, bischlorophenyl carbonate, dinaphthyl carbonate, 2-tolyl-4-tolyl carbonate, dimethyl carbonate, diethyl carbonate, or dialkyl carbonate. Carbonate and 1,6-hexanediol, neopentyl glycol, 1,4-butanediol, 1.8
- octanediol, l,4-bis-(hydroxymethyl)-cyclohexane, dipropylene glycol or the above diol compounds and oxalic acid, malonic acid, succinic acid,
Adipic acid, azelaic acid.

It can be obtained by a transesterification reaction with a polyester diol, which is a reaction product of a dicarboxylic acid such as hexahydrophthalic acid. Carbonate diols can also be obtained by reacting phosgene with the above diols,
The carbonate diol thus obtained is a monocarbonate diol having one carbonate structure in the molecule or a polycarbonate diol having two or more carbonate structures in the molecule. These are easily available on the market. For example, Desmophen 2020E
(manufactured by Sumitomo Bayer ■, y-=z000), D
N-980 (made by Japan Polyurethane ■, Mw=2000
), 0N-981 (made by Nippon Polyurethane ■, M-=
1000), DN-982 (made by Nippon Polyurethane ■,
Ki! , =2000), DN-983 (manufactured by Nippon Polyurethane Co., Ltd., 'yl, =1000), and the like.

The 2P material, which is the ultraviolet curable resin composition of the present invention, is mainly composed of a photopolymerizable prepolymer, a photopolymerizable hexamer, and a photopolymerization initiator. It is a polymer that can be polymerized and is an important component that forms the 22 skeleton. ``Photopolymerizable monomers play the role of lowering the viscosity of the prepolymer, and when irradiated with light (mainly ultraviolet rays), they also participate in polymerization.

The photopolymerizable heptamer used in the present invention has the linear formula (
Examples include acrylic esters (B) represented by I).

(I) As described in JP-A-57-107575, this is a compound obtained by condensing trimethylolpropane and 2,2-dimethyl-3-oxypropanal and reacting with acrylic acid. The resulting product is neopentyl glycol modified trimethylolpropane diacrylate.

Further, in order to increase the photocuring speed, the ultraviolet curable resin composition of the present invention generally contains (C) a photopolymerization initiator in addition to the photopolymerizable prepolymer and the photopolymerizable hexamer. be.

The photopolymerization initiator is not particularly limited and a wide range of compounds can be used as long as it absorbs ultraviolet light and generates radicals. A typical example is p
-tert-butyltrichloroacetophenone, 2.
2°-jethoxyacetophenone, 2-hydroxy-2
- Acetophenones such as methyl-1-phenylpropan-1-one; Ketones such as benzophenone, Michler's ketone, 2-chlorothioxanthone, and 2-isopropynethioxanthone; Benzoin ethers such as benzoin and benzoin isopropyl ether; benzyl and benzyldimethyl Examples include benzyl ketals such as ketal and hydroxycyclohexylphenyl ketone.

It is preferable to add a sensitizer together with such a photopolymerization initiator because it accelerates the photocuring rate. As the sensitizer, for example, when benzyl is used as a photopolymerization initiator, amine compounds such as n-butylamine, di-n-butylamine, triethylamine, and diethylaminoethyl methacrylate are suitable.

In addition, in order to maintain an appropriate liquid viscosity, the ultraviolet curable resin composition of the present invention needs to contain a photopolymerizable monomer such as the compound represented by the above-mentioned structural formula (I). Furthermore, the following compounds can also be contained. Monofunctional (meth)acrylates such as dicyclopentadiene ethoxy mono(meth)acrylate, hydrogenated dicyclopentadiene ethoxy mono(meth)acrylate, and isofornyl (meth)acrylate because of their low water absorption; 1. : l-butanediol di(meth)acrylate, l,4-butanediol di(meth)acrylate, l,6-hexanethiol di(meth)acrylate, diethylene glycol di(meth)acrylate, neobentyl glycol di(meth)acrylate Difunctional (meth)acrylate compounds such as acrylate; Bifunctional (meth)acrylate compounds such as trimethylolpropane tri(meth)acrylate and trimethylolethane trimethacrylate.

The concentration of carbonate diol diacrylate as (A) prepolymer component in the ultraviolet curable resin composition is 10
-50% by weight, preferably 10-30% by weight, the concentration of (B) acrylic ester represented by structural formula (I) is preferably 60-90% by weight, and the concentration of (C) photoinitiator is It is 0.5 to 5% by weight.

Further, the viscosity at room temperature of the ultraviolet curable resin composition having the above composition is 10.000 cps or less, more preferably 1
A range of 0.00 to 1000 cps is appropriate.4 This makes it possible to completely cover the unevenness of the mold surface.

Obtained in this way. A liquid ultraviolet curable resin composition is coated on the surface of the stanbar in which preformat signals and guide grooves are carved, and a transparent disk is pressed onto the surface to give a uniform thickness (e.g., 20 to 100 B). Next, an optical record carrier can be obtained by irradiating ultraviolet light through the transparent disk to cure the liquid resin, and then peeling the transparent disk together with the cured resin film attached thereto from the stamper.

As the transparent disc, vinyl chloride/vinyl acetate copolymer, polymethacrylate, polycarbonate, polystyrene, epoxy resin, glass, etc. are used.

An optical recording medium can be produced by applying an organic or inorganic recording medium to the surface of the obtained optical recording carrier by a method such as vapor deposition or coating. The created optical recording medium can be read only or recorded/played/erased using a light beam.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Production Example 1 Carbonate diol diacrylate production side stirrer,
A 2g reactor equipped with a temperature sub-tube device, a thermometer, and a condenser,
Carbonate diol (manufactured by Nippon Polyurethane, DN-
983, Mw = 1000) 7000 parts by weight, 121 parts by weight of acrylic acid, 14 parts by weight of p-toluenesulfonic acid,
Hydroquinone 1.0 parts by weight, benzene 560 parts by weight,
140 parts by weight of cyclohexane is charged and heated, the produced water is distilled and condensed together with the solvent, only the water is removed from the system in a separator, and the solvent is returned to the reactor. When 25.5 parts by weight of water is produced, it is cooled. The reaction product obtained by the reaction at a temperature of 80 to 85°C was mixed with 96 Oi parts of benzene and 2 parts of hexane.
The solution was dissolved in 40 parts by weight, neutralized with a 20 wt% caustic soda aqueous solution, and then washed with a 20 wL% saline solution. The solvent was distilled off under reduced pressure to obtain 690 parts by weight of a pale yellow liquid (carbonate diol diacrylate).

Production Example 2 In the same reactor as Production Example 1, carbonate diol (manufactured by Nippon Polyurethane, DN-982: n, = approx. 200
0) Charge 7000 parts by weight, 61 parts by weight of acrylic acid, 6 parts by weight of p-toluenesulfonic acid, 0.4 parts by weight of hydroquinone, 560 parts by weight of benzene, and 140 parts by weight of cyclohexane, and the produced water becomes 12.6 parts by weight. 0 reaction mixture, which was reacted in the same manner as in Production Example 1, was mixed with benzene 12
00 parts by weight and 300 parts by weight of cyclohexane, neutralized, washed, and solvent removed in the same manner as in Production Example 1 to obtain a pale yellow liquid (carbonate diol diacrylate) 65
4 parts by weight were obtained.

Examples 1 to 4 and Comparative Examples 1.20 Preparation of ultraviolet curable resin composition (A) carbonate diol diacrylate, (B) acrylic ester, and (C) photopolymerization initiator as shown in Table 1 below.
Blend the composition as shown in , make a homogeneous solution with a stirrer at room temperature, and then pass it through a milliborea filter (0.45μ
) to obtain a liquid ultraviolet curable resin composition.

However, the photopolymerization initiator Irgacure 184 in Table 1 is l-
Hydroxycyclohexylphenylketone, Darocure 1173 refers to 2-hydroxy-2-methylpropiophenone.

O Creating an optical record carrier A nickel-plated stub bar with preformat irregularities on its surface is coated with the ultraviolet curable resin composition shown in Table 1 above, and a silane coupling agent (Nippon Unicar ■, A174) spin-coded outer diameter
A glass substrate with a diameter of 130 m and an inner diameter of 15 m was crimped so that the film thickness of the ultraviolet curable resin composition was 2 cm,
233 mW/am” UV illuminance (wavelength 365 nm)
After irradiation with ultraviolet light, the substrate was peeled off from the stand bar together with the ultraviolet curable resin film to obtain an optical record carrier having preformat signals and guide grooves on its surface.

On the optical record carrier obtained as described above in the procedure for creating an optical recording medium, a layer of Si3N with a thickness of 800 mm was formed by a sputtering method. GdTb, layer thickness 400
Human amorphous 7bFeX! ! - A magneto-optical recording layer was laminated, and an Si3N layer with a thickness of 800 layers was further formed. Next, the medium and the glass substrate were bonded together using an adhesive to create an optical recording medium.

Next, an environmental durability test (70°C 190% R, II, 5000 hr.
) Appearance defects before and after (2P layer peeling from the substrate, 2P
Table 2 shows the results of measurements of wrinkles in the layer, pitting corrosion in the recording layer, etc.) and CAH.

(Note) (1) Glass transition temperature (Tg): Dynamic viscoelasticity was measured under the conditions of a frequency of IMHz and a heating rate of l''C/■in, and the peak of α dispersion of tanσ was taken as Tg.

(2) Water absorption was determined by immersing the 2P cured product in pure water at 20° C. for 24 hours, measuring the weight before and after the test, and expressing the percentage increase in weight due to water absorption.

(3) Curing shrinkage rate was determined by the density method, which measures the density of 2P before and after curing.

(4) Inspection for external defects such as peeling of the 2P layer, occurrence of wrinkles, occurrence of pitting corrosion of the recording layer, etc. is performed using an optical microscope (x50), and the presence or absence of defects of size 10100p 100p■ on the disc surface is performed. Examined.

(5) Measurement of recording sensitivity is C/N of 40 dB or more.
It shows the recording laser power (mW) to obtain the value, and if this value does not change, it means that the recording sensitivity does not change.

Next, an environmental durability test (70°C,
Table 3 shows the results of measuring the recording sensitivity around 90% R, H, 5000 hr).

Table 3 (Note) The heating loss start temperature was measured by TG-DSC at a heating rate of 2°C/layer in.

Furthermore, using the same stamper used to create the optical record carriers of Examples 1 to 4 and Comparative Example 1.2 above,
Table 4 shows the total number of 22 molded shots when 2P molding was performed continuously and the results of measuring the C/N of the optical recording medium produced using the optical recording carrier at that time.

Table 4 [Effects of the Invention] As explained above, the optical recording carrier of the present invention is made of a curable resin made of a specific ultraviolet curable resin composition formed on a transparent disk by the 2P method. Since it has a preformat signal and a guide groove, the following effects can be obtained.

■The shape of the preformat signal and the edge of the guide groove has sufficient heat resistance even under high temperatures, so even if an optical recording medium with a recording layer provided on an optical record carrier is subjected to an environmental durability test, /N never decreases.

■Since the preformat signal and guide groove have sufficient moisture resistance, even if an optical recording medium with a recording layer provided on an optical record carrier is subjected to an environmental durability test, the recording layer will deteriorate due to water absorption and permeation. , no corrosion occurs.

■Since the preformat signal and guide groove have sufficient hardness, there is no peeling between the substrate and the 2P layer even in environmental durability tests of optical recording media in which a recording layer is provided on an optical recording carrier. It never occurs.

■Since the preformat signal and the guide groove have few heating volatile components, the recording sensitivity changes due to the low molecular weight substances that heat and volatilize in optical recording media in which an amorphous magnetic recording layer is provided as a recording layer on an optical recording carrier. There's very little to do.

■Because the curing shrinkage of the preformat signal and guide groove is small, wrinkles do not occur in the preformat signal and guide groove even if an environmental durability test is performed.

■Pre-format signals and guide grooves made of ultraviolet curable resin composition have good releasability from the stanbar mold.
Residual force of the 2P material on the stambar (without the stambar)
It is possible to perform 2P molding continuously without washing, and it is possible to obtain an optical record carrier with high productivity.

Claims (3)

[Claims] (1) An optical record carrier having preformat signals and guide grooves made of a curable resin formed by the 2P method on a transparent disk, wherein the curable resin (A) has an average molecular weight of 500 as a prepolymer component. ~5000 carbonate diol diacrylate, (B) a compound represented by the following structural formula (I) as an acrylic acid ester component, and (C) an ultraviolet curable resin composition containing a photopolymerization initiator. Optical record carrier characterized by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (2) The ultraviolet curable resin composition contains (A) at least 10% by weight of carbonate diol diacrylate;
At least 60% by weight of (B) acrylic ester represented by structural formula (I), and 0.5 to 0.5% of (C) photopolymerization initiator.
The optical record carrier according to claim 1, containing 5% by weight. (3) The transparent disk is made of polymethacrylate,
The optical record carrier according to claim 1, which is made of polycarbonate, polystyrene, epoxy resin, or glass.