JPH02214040A - Information recording medium - Google Patents

Abstract

PURPOSE:To allow the formation of a good-quality recording film and the increase of the density of the recording medium by forming the recording medium of a substrate formed with prescribed 2P layers as well as a recording layer and a protective layer on a base and using the 2P layers having the Young's modulus within the range of prescribed values and thereby producing the recording medium. CONSTITUTION:This recording medium consists of the substrate formed with the UV curing resin (2P) layers having grooves for information recording on the base as well as the recording layer which is formed on the substrate and the optical or magnetic state of which is changed by the impression of laser light or magnetic field and the protective layer which is formed thereon. The information recording medium is produced by using the 2P layers which have the Young's modulus at 200 deg.C within the range of >=70kg/mm<2>. A compd. which is at least either of the compds. expressed by a general formula (I) or (II) and is compounded with a photopolymn. initiator uniformly at 0.1 to 10wt.% is used as this 2P resin. X denotes a (meth)acryloyl group; n denotes 3 to 6; Y denotes a hydroxyl group. Since the recording film having excellent heat resistance and good quality is formed by this medium, the increase of the density is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a disk-shaped or card-shaped information recording medium on which information can be recorded and reproduced (and erased) optically or magnetically.

[Prior art and problems to be solved by the invention] Information recording media (hereinafter simply referred to as "medium" or "media"), which are indispensable for the recent information society, have recently become increasingly denser and larger. Progress is being made towards increasing capacity. As one means of making such media even more dense, attempts are being made to form minute optical spots or minute magnetic domains by irradiating the medium with laser light or the like. Regarding recording films, research and development of magneto-optical films and perpendicular magnetization films are being actively pursued. In addition, one way to increase the capacity of media is to physically or chemically form grooves on its surface (resin film, substrate surface, etc.) in advance, and to obtain control signals while detecting the groove signals. Media for recording and reproducing information are also being developed.

Magneto-optical disks are a typical example, but in the field of magnetic disks, technology has also been proposed in which grooves are formed and used for tracking.
No. 72 (capacitance method), JP-A-51-42485 (
(optical method) etc. are already known. Optical discs are ahead of the technology for forming tracking grooves on recording media, but this method involves injection molding thermoplastic resin using a mold called a stamper, and ultraviolet curing technology on a transparent resin substrate. There is a method of forming resin (2P)M and then curing it (2P method).

The present applicant has conducted intensive studies on recording media to realize high density and large capacity layers, and found that it is necessary to form minute magnetic domains in both magneto-optical films and perpendicularly magnetized films. discovered that it is important to reduce the particle size, excellent orientation, and high coercive force of the recording film. It has been found that these properties can be achieved by sputtering or vacuum deposition at high substrate temperatures.

Therefore, the present applicant searched for a heat-resistant substrate that could withstand such sputtering or vapor deposition, but injection-molded thermoplastic resin substrates have the property of rapidly softening once the glass transition point (Tg) is exceeded. It was found that a substrate made of a material with a high transition point was not suitable for practical use because tracking grooves and addresses were insufficiently formed. On the other hand, in experiments on 2P substrates using commercially available 22 (ultraviolet curing resin) resin, tracking grooves and addresses were sufficiently formed, but the heat resistance was poor, and fine wrinkles were generated on the 2P surface when sputtering was performed. However, it turned out that it was not suitable for practical use.

From the above experimental results, it was concluded that the substrate should have a structure in which a support and a 2P layer are laminated, and that a new 2P resin with high heat resistance should be developed.

[Means to solve the problem]

The present invention provides a substrate in which an ultraviolet curable resin layer having information recording grooves is formed on a support, and a substrate formed on this substrate,
It consists of a recording layer whose optical or magnetic state changes by the application of laser light or a magnetic field, and a protective layer formed on this recording layer, and the above-mentioned ultraviolet curable resin layer has a Young's modulus of 70 kg/vd at 200°C. The above-mentioned problems have been solved by providing an information recording body produced using the above-mentioned materials and a method for manufacturing the same.

〔Example〕

An embodiment of the information recording medium of the present invention will be described. First, the support is a thermoplastic resin.

The 0-order 2P (ultraviolet curing resin) layer may be made of any material such as thermosetting resin, glass, or metal.
A material having a Young's modulus at ℃ of 70 kg/mm2 or more is used. 2PIl! having such properties! The fat is a compound having the chemical formula shown below or C
H20-X CH3CH2CCH20-X (II
) A resin containing at least one of the compounds CH20-X and a photopolymerization initiator such as Darocur 1173 uniformly blended therein in an amount of 0.1 to 10% by weight is used. In addition, in both formulas, X is a (meth)acryloyl group (TL=3
~6), Y is a hydroxyl group.

Next, regarding specific examples and manufacturing methods thereof, polyethylene terephthalate and Lumirror Q77 (
The explanation will be given by taking as an example a disk in which a CoCr perpendicular magnetization film and a carbon film are formed on a 2P resin by sputtering using a 2P resin (Toshi Co., Ltd.). The 2pH resin was formed on the support by the well-known 2P molding method.

Comparative Example 1> As a 2P resin ■ UVX-33120 from ThreeBond
A substrate was prepared using At this time, the bits on the stand bar were correctly transferred to the surface of the substrate, and the surface was smooth. Next, CoCr was sputtered by 2000 people at a substrate temperature of 20°C and an Ar gas pressure of 0.8 mTorr, and when taken out, the entire surface was white, which was observed under a microscope.

Upon investigation, it was discovered that there were fine wrinkles. It was also discovered that some of the bits were distorted. When the magnetic properties of this disk were measured using a VSM (vibrating sample magnetometer), the vertical component Hc (coercive force) was 17
1 (Oe), which is insufficient for perpendicular magnetic recording.

Comparative Example 2> 2Pv! LE-362 from Toyo Ink Seisakusho Co., Ltd.
A substrate was prepared using Comparative Example 9, and a disk was prepared in the same manner as in Comparative Example 1 except for the following. In this case as well, the bits on the stamper were correctly transferred to the surface of the substrate, exhibiting a smooth surface condition, and no distortion of the bits was observed even after CoCr sputtering. However, the vertical component measured by VSM Hc was 170 as in Comparative Example 1, which was an insufficient value for perpendicular magnetic recording.

Comparative Example 3> A substrate was produced under the same conditions as Comparative Example 2, and the substrate temperature was 80°C.
, Ar gas pressure = 0.8+1 TOrr, CoCr 2
When taken out after sputtering, the entire surface was white, and as a result of microscopic observation, microscopic wrinkles had formed and covered the entire surface. Although the perpendicular component Hc measured by VSM was improved to 240 r:J, this value was still insufficient for perpendicular magnetic recording.

It has been conventionally said that Hc, the perpendicular component of the magnetic properties of CoCr, increases as the substrate temperature rises, and a similar tendency was observed in each of the above comparative examples.

Therefore, in order to obtain the minimum required Hc700tj, it is considered necessary to heat the substrate temperature to at least 200°C.

Therefore, in order to evaluate the heat resistance of 2P resin, TMA
When the temperature-Young's modulus characteristics of the 2P resin alone were investigated by (thermomechanical analysis), it showed the characteristics as shown in Figure 1 of Lta UVX-3S120 and LE-36294,1 used in Comparative Examples 1 and 2 above. . That is, uvx-ssi2o is 20
It is characterized by rapid softening in the low temperature range of ~50°C.

Therefore, even if the temperature of the substrate was set at 20° C., it is thought that the surface temperature rose due to exposure to plasma during sputtering, and the softened resin floated on the support, causing wrinkles.

On the other hand, LE-3629 withstood sputtering at a substrate temperature of 20°C, but wrinkled at a substrate temperature of 80°C.

The Young's modulus of this resin at 20°C and 80°C is 105, respectively.
kg/- and 64 kg/w (and is thought to further decrease during sputtering.

From the above experimental results, the conditions for Young's modulus that do not cause wrinkles (substrate surface does not whiten) are approximately 70hg/+tj1 or more,
It can be said that it is desirably 100 kg/d or more.

Therefore, in order to investigate and study 2P resins with high heat resistance, ■DPHA, ■M-309. ■DPCA-60, ■M
-315. Select six types of oligomers: ■MANDA, ■R-551 (■ and ■ are products of Toagosei Chemical Industry ■, others are products of Nippon Kayaku ■) (each molecular structure is shown in page 13, page 1).
Photoinitiator D
A 2P resin was prepared by adding 3% by weight of arOCtlr 1173 (manufactured by Merck Japan). The temperature-Young's modulus characteristics of these cured samples are shown in Figure 2.As is clear from this figure, at 200℃
Oligomers with a Young's modulus of 4 or more are only ■ and ■, but both have a Young's modulus that is approximately constant against temperature changes, and can be said to be stable resins. Comparing the molecular structures of oligomers ■, ■ and other oligomers from Table 1, ■.

It was found that only (1) had a structure capable of forming a three-dimensional crosslink, that is, at least a trifunctional or higher functional (meth)acryloyl group. Another condition is that the length of the chain between each acryloyl group is short.

<Example 1> DPHA manufactured by Nippon Kayaku ■ and Da manufactured by Merck Japan ■
A 2P resin was obtained by adding rOCur 1173 in an amount of 3% by weight of the total. A substrate was produced using this resin in the same manner as in Comparative Example 1 above. Then, substrate temperature = 150'C, Ar
CoCr was sputtered by 2000 people at a gas pressure of 0.811 ■orr. When the surface was observed and investigated using a microscope, no distortion of the bit was observed, the surface was smooth, and no wrinkles were observed.
When the magnetic properties were measured by VSM, the vertical component H
c (coercive force) was 800◇, which was a level value sufficient for perpendicular magnetic recording.

<Example 2> Darocur 1 on M-309 of Toagosei Chemical Industry Co., Ltd.
A 2P resin was obtained by adding 3% by weight of 173. A substrate was prepared using this resin in the same manner as in Example 1, and then the substrate temperature was 150°C and the Ar gas pressure was 0.81 Torr.
CoCr was sputtered by 2000 people at r.

In this case as well, no pit distortion or wrinkles were observed on the substrate surface. Further, the vertical component Hc was 800σ, which was a good value.

<Example 3> Weigh 50% by weight of DPHA and M-309.

After mixing, 3% by weight of Darocur 1173 was added to the mixture to obtain a 2P resin. A substrate was produced using this resin in the same manner as in Example 1, and then Co
After sputtering 2000 Cr, carbon was added as a protective film at 300 mTorr with Ar gas pressure = 13 mTorr.
People sputtered. In this case as well, no wrinkles or bit distortion were observed, and the vertical component Hc (coercive force) was 800.
d, which was a good level value. When we conducted a recording/reproduction experiment using a ring head, we found that D6111 was 70 kF.
A reproduction output of cI, C/N = 50 da was obtained.

In addition, 22 resin of this Example 3 was cured alone, and TM
When temperature-Young's modulus characteristics were measured by A (thermomechanical analysis), results as shown by the broken line in FIG. 2 were obtained.

As described above, the 2P resin according to the present invention has excellent image clarity and serves as a substrate on which a high-quality perpendicularly magnetized film can be formed.

In the above description, a perpendicularly magnetized film was used as the OH, but CoNi, C.

A similar effect can be obtained in in-plane magnetized films such as NiCr and CoPt because there is a correlation between the substrate temperature and Ha (in-plane component). Also, TbFe, TbFeCo, DyFe,
Even in the case of a magneto-optical film such as GdFe, a high-quality film with high Hc (vertical component) can be obtained at a high substrate temperature.

By the way, in magneto-optical films, the Kerr rotation angle (θ
k) and the Curie point (Tc) of the recording film is known. By using the heat-resistant substrate used in the media of the present invention, it is possible to select a material with a high Tc, and as a result, the S/N ratio can be improved. Improvements can be made. In addition to these magnetic properties, film formation at high substrate temperatures also contributes to improved adhesion between the substrate and recording film.
It also has the effect of increasing the reliability of the medium (disk) to a new level.

Furthermore, in the case of conventional magneto-optical disks and optical disks,
During recording, the laser beam heats the substrate, which may deform the guide groove or cause cracks in the recording film.However, in the case of the 2PI resin according to the present invention, such inconveniences are extremely rare, and recording is possible. Another advantage is that the laser output can be set high.

Although polyethylene terephthalate was used as the support in each of the examples, the medium of the present invention is not limited to this, and other media such as polycarbonate, polysulfone, polyimide, polyethersulfone, polyetherimide, etc. Resin, metal plates, and even glass plates can be used.

In addition, Darocur1 is used as a photopolymerization initiator for 2P resin.
173 was used, but in addition, benzyl 1-benzoin, benzophenone, 4-methoxybenzophenone, benzyl dimethyl ketal, benzoin ethyl ether, and benzoin iso-10 pyl ether.

Myrrhazketone, anthraquinone, 2-methylanthraquinone, acetophenone, αα-dichloro-4-phenoxyacetophenone, p-tertbutyltrichloroacetophenone, methylorthobenzoylbenzoate, 2-chlorothioxanthone 2 and 2,4-diethylthioxanthone can also be used. be. Furthermore, an amine compound may be added as a photopolymerization accelerator, if necessary.

Furthermore, in order to improve adhesion to the support, a monomer or silane coupling agent having good wettability with the support may be added.

The information recording medium of the present invention has a feature of providing a highly hard substrate, but if it is necessary to have flexibility, it may be possible to use HX-820, HX-220, etc. manufactured by Nippon Ihiyaku. It is also possible to add flexibility monomers. However, in this case, the heat resistance decreases, so it is important to limit the amount added to the extent that the features and effects of the present invention are not lost.

〔effect〕

Like soft soil, the information recording medium of the present invention has excellent heat resistance and can form a high-quality recording medium, so it has features such as being able to achieve higher density in perpendicular magnetic recording media and the like.

[Brief explanation of the drawing]

Figure 1 is a temperature-Young's modulus characteristic diagram of a typical 2PVA resin alone, and Figure 2 is a temperature-Young's modulus characteristic diagram of a 2P resin cured sample made with a typical oligomer and each example of the recording medium of the present invention. be. Figure 11 Patent applicant: Kunio Umiki, Representative of Victor Japan Co., Ltd.

Claims (2)

[Claims] (1) A substrate on which an ultraviolet curable resin layer with grooves for information recording is formed on a support, and a recording layer formed on this substrate whose optical or magnetic state changes upon application of laser light or a magnetic field. and a protective layer formed on the recording layer, and is characterized in that the ultraviolet curable resin layer is produced using a material having a Young's modulus at 200° C. of 70 kg/mm^2 or more. Information recording medium. (2) The above-mentioned ultraviolet curable resin layer is made of the following (I) or (II)
) containing at least one of the compounds represented by the general formula;
The information recording medium according to claim 1, which is obtained by curing an ultraviolet curable resin composition in which a photopolymerization initiator is uniformly blended in an amount of 0.1 to 10% by weight. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・・・・
(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・・・・
(II) {However, X is a (meth)acryloyl group (n=3 to 6), Y is a hydroxyl group}