JPH0449090A - Write-once type optical recording member - Google Patents

Abstract

PURPOSE:To obtain the title recording material having good recording and reproducing properties and excellent in environment resistance by forming a recording medium from a plasma polymerization film of Te and octafluorocyclobutane and forming an undercoat layer and a protective layer from a plasma polymerization film of FCB. CONSTITUTION:An undercoat layer composed of a plasma polymerization film of FCB is formed to a substrate. Plasma polymerization is carried out by supplying FCB into a vacuum tank held to 10<-5> - 10<-1> Torr in a gaseous state and carrying out discharge by a high frequency power supply to bring FCB to plasma state to deposit the same on the substrate as a polymerization film. Subsequently, a recording medium composed of a plasma polymer or Te and FCB is formed to the substrate on which the undercoat layer of the FCB plasma polymerization film is formed. The recording medium can be formed by carrying out the vacuum vapor deposition of Te while the plasma polymerization of FCB is performed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention has high sensitivity and a carrier-to-noise ratio (hereinafter referred to as C/N
The present invention relates to a write-once optical recording member that has a high environmental resistance (denoted as ) and has excellent environmental resistance.

<Prior art> In recent years, optical recording materials such as optical disks are capable of high-density recording and random access, and are also portable, which is not the case with conventional information recording materials such as magnetic disks and magnetic tapes. It is attracting attention in the field of information recording for convenience stores, videos, etc.

Due to its recording and playback characteristics, optical discs are read-only type,
They can be roughly classified into write-once type and erasable type.

Among these, the write-once optical disc refers to one on which recording is possible only once. Although this type of optical disk cannot erase recorded information, it is expected to be used in the field of recording information that needs to be stored for a long period of time or that is difficult to erase.

In write-once optical discs, small holes are formed by sublimation and melting of the recording medium in the area irradiated with the writing laser pulse, and information is read out based on the difference in reflectance and transmittance between recorded and non-recorded areas. Optical discs are well known.

A1 and B1 are used as recording media for small hole-forming optical discs.
It is known that single thin films of metals, semimetals, and semiconductors such as , Te, Pb, and Mo can be used. However, single thin films of these metals, metalloids, and semiconductors have insufficient recording/reproducing characteristics, low C/N, low sensitivity, and problems with environmental resistance. Various studies have been conducted to improve the characteristics of

JP-A No. 57-98394 and others disclose that by using a composite film of semimetal such as Te and plasma polymer of organic substance such as C52 as a recording layer, stability over time can be improved and good recording and reproducing characteristics can be obtained. It has been shown that it can be obtained.

JP-A-59-90246 discloses that a highly sensitive write-once optical recording member can be obtained by using a plasma polymerized film of unsaturated fluorinated carbon such as tetrafluoroethylene as the underlayer.

JP-A-63-166045 describes methane, ethylene,
It has been shown that plasma polymerized films of organic compounds such as methanol, acetone, benzene, carbon disulfide, and pyridine can be used as protective layers.

<Problems to be Solved by the Invention> Improvements in recording/playback characteristics using conventional methods may not have sufficient environmental resistance, or may still have insufficient sensitivity or C/C ratio to be used in high-speed rotation drives with high transfer rates in recent years. Since N is low, satisfactory recording/reproducing characteristics are not necessarily obtained.

An object of the present invention is to provide a write-once optical recording member that has good recording and reproducing characteristics such as high sensitivity and high C/N, and has excellent environmental resistance.

The present inventors focused on saturated fluorinated carbon, which had not been used in the past, and as a result of intensive studies, they found that even among saturated fluorinated carbons, cyclic PCB forms a uniform film through plasma polymerization, and a write-once optical The inventors have discovered that the above objects can be achieved by using the composition in the recording layer, underlayer and protective layer of a recording member, leading to the present invention.

<Means for Solving the Problem> That is, the present invention provides a write-once optical recording member having a recording medium, an underlayer between the recording medium and a substrate, and a protective layer on the recording medium, in which the recording medium is made of Te. and a plasma-polymerized film of octafluorocyclobutane (hereinafter referred to as PCB), and the base layer and the protective layer are made of the plasma-polymerized film of PCB.

Substrates used in the present invention include those molded from polycarbonate or polymethyl methacrylate, and so-called 2P substrates in which groups and formats are formed on glass or polycarbonate using the 2P method. Examples of substrates that can be used include:

A base layer of a plasma polymerized PCB film is formed on the substrate. In plasma polymerization, PCB is supplied in a gaseous state into a vacuum chamber of 10 -S to 10 -1 Torr, and discharge is performed using a high frequency power source, thereby converting the PCB into a plasma state and depositing it as a polymer film on the substrate. The applied power is 50 to 500
W is commonly used. Further, the PCB plasma polymerized film as an underlayer is usually deposited to a thickness of about 10 to 300 layers.

Next, a recording medium made of a plasma polymer of Te and PCB is formed on the substrate on which a base layer of a PCB plasma polymer film is formed. These recording media can be formed by performing vacuum evaporation of Te while performing plasma polymerization of PCB.

After forming a base layer and a recording medium on a substrate, a protective layer of a PCB plasma polymerized film is formed. The formation method is the above-mentioned F'
This is done in the same way as the base layer of the CB plasma film. The appropriate thickness of the protective layer is several to 100 Å.

Further, after the above-described film formation for stabilizing the recording/reproducing characteristics of the recording medium is performed, Te is crystallized at about 50 to 100°C.

<Effects of the Invention> According to the present invention, compared to conventional write-once type optical recording members,
A write-once optical recording member having high sensitivity, high C/N, and excellent H# boundary resistance is provided.

Furthermore, since only the same plasma polymerized film is used, there is no plasma instability during switching compared to the case where different plasma polymerized films are used, and the film can be formed efficiently.

<Example> The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited to these.

Example 1 A 130M-φ substrate with a pregroup was set in a vacuum evaporation device, PCB gas was introduced, and a high frequency coil was powered at 200W.
A plasma polymerized film of PCB was formed on the substrate by about 40 people.

Further, while plasma polymerization continues, Te is evaporated from the resistance heating board, and the Te-PCB composite recording medium is heated to about 2
00 people formed. However, the high frequency power at the time of forming the composite film was 100W.

Next, the vapor deposition of Te was stopped, a high frequency power of 200 W was applied, and a PCB was formed by plasma polymerization to form a protective layer.

The write-once optical recording member thus obtained (hereinafter referred to as a single disk) was taken out of the vacuum deposition apparatus, and the relative humidity was 4.
Te was crystallized at 70° C. for 2 hours in an open state of 0% or less.

The recording and playback characteristics of the obtained single disk were measured using an 839nm laser beam, and the laser power during playback was determined by Qogm.
The measurement was performed using W and changing the laser power during recording.

In addition, the recording position is a radius of 40 carp, a rotation speed of 180 Qrpm,
The laser irradiation pulse was 50 ns at a frequency of 5 MHz.

As a result, the C/N was 52 dB, and the sensitivity (recording power value at which the carrier was 6 dB below the highest value) was 5.4 mW.
It showed high C/N and high sensitivity.

Examples 2 to 5 Write-once optical recording having a PCB plasma-polymerized underlayer, a Te-PCB composite recording medium, and a PCB plasma-polymerized protective layer in the same manner as in Example 1 except that the thicknesses of the underlayer and the protective layer were changed. After producing the member, Te was crystallized.

The initial recording and reproduction characteristics of the obtained write-once optical recording member were
Shown in the table. All exhibited high sensitivity and high C/N.

Table 1 Comparative Example 1 The organic compound to be subjected to plasma polymerization was hexafluoropropylene (hereinafter referred to as 6FP), and the 6FP plasma polymerization base layer,
A write-once optical recording member consisting of a Te/6FP composite recording medium and a 6FF plasma polymerized protective layer was produced. The film thickness of each layer was approximately 40 layers for the base layer, approximately 200 layers for the recording medium, and approximately 20 layers for the protective layer. After crystallizing Te in the same manner as in Example 1, the initial recording characteristics were measured, and the sensitivity was 5. Although the QmW was high, the C/N was low at 45 dB.

Comparative Example 2 The organic compound to be subjected to plasma polymerization was carbon disulfide (hereinafter referred to as C
32), C82 plasma polymerized underlayer, Te-
After producing a write-once optical recording member consisting of a C32 composite recording medium and a C8° plasma polymerized protective layer, Te was crystallized. The film thickness of each layer is approximately 40 layers for the base layer and approximately 200 layers for the recording medium.
There were 30 people in the protective layer vJ. After crystallizing Te in the same manner as in Example 1, the initial recording characteristics were measured, and the C/N was as high as 52 dB, but the sensitivity was 5.4 mW.
It was low.

Comparative Example 3 After preparing a write-once optical recording member consisting of two layers: about 40 6FP plasma polymerized films as a base layer and a Te-C52 composite recording medium as a recording medium, Te was crystallized.

The initial recording characteristics were a C/N of 52 dB and a sensitivity of 4.3 mW, making it a high-sensitivity, high-C/N medium.

However, as shown in the environmental resistance test results, the environmental resistance is poor.

(Environmental resistance test) The disk veneers of Examples 1 to 5 and Comparative Examples 1 to 3 were
The sample was placed in an environmental test tank at 80% RH for 500 hours to examine changes in reflectance. The results are shown in Table 2 as a reflectance ratio (ratio of reflectance after 500 hours to initial reflectance).

The one according to this example had a small change in reflectance and was excellent in environmental resistance.

Table 2

Claims (1)

[Claims] 1. A write-once optical recording member having a recording medium, an underlayer between the recording medium and the substrate, and a protective layer on the recording medium, wherein the recording medium is made of a plasma polymerized film of Te and octafluorocyclobutane, A write-once optical recording member in which a base layer and a protective layer are made of a plasma polymerized film of octafluorocyclobutane.