JPS63237993A - Optical recording material - Google Patents

Abstract

PURPOSE:To obtain an optical recording material excellent in both sensitivity and weatherability (stability) by composing a recording layer of a thin film of tellurium oxide, and providing a sensitizing layer composed of a similar thin film of tellurium oxide thereon, while using a weak oxide on the recording layer side and using a strong oxide on the sensitizing layer side. CONSTITUTION:When a thin film of a lower oxide of tellurium is used as a recording layer 3, it has a sensitivity comparable to that obtained by using elemental tellurium, and is excellent in stability and weatherability. When a sensitizing layer 4 composed of a thin film of a higher oxide of tellurium is provided on the recording layer 3 in a laminate form, the weatherability is further enhanced. Even when the laminate is adhered to other base to produce a recording medium, lowering in the sensitivity or the scattering in a recorded shape will not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording material in which optical information can be recorded by forming pits in a recording layer by irradiation with a laser beam or the like.

[Background of the invention]

Conventionally, high-density optical information recording methods involve melting or vaporizing metals, semimetals, or organic compounds using highly focused recording light such as laser light to form information pits consisting of recesses and holes. method is known.

For example, optical recording materials have been proposed in which a thin film of a low melting point metal such as tellurium (Te) or bismuth (Bi) is provided on a support, but among these, Te thin film has excellent recording and reproducing sensitivity with laser beams. Therefore, its use is considered promising.

However, although the Te thin film has excellent sensitivity, it has the problem of poor weather resistance as a material. For example, the sensitivity and reflectance may decrease over time due to the influence of the external environment, or in severe cases, cracks may occur in the thin film. There is also.

By the way, as a method to improve the weather resistance of thin films, T
A method of alloying e is effective. However, it is generally difficult to reproducibly form a thin film made of a Te alloy on a support. For example, sputtering or vapor deposition can be used to form an alloy thin film, but When a Te alloy with the same composition as the ratio is formed by sputtering, the target used becomes extremely expensive, which is economically disadvantageous.On the other hand, when using vapor deposition, it is necessary to use a multi-component vapor deposition method. Because of this, the equipment used is expensive and there are problems in terms of productivity.

[Summary of the invention]

The present invention has been made in view of the above-mentioned points, and provides an optical recording material that is excellent in both sensitivity and weather resistance (stability), is relatively easy to produce, and is capable of reducing manufacturing costs. The purpose is to

The present inventors constructed the recording layer from a tellurium oxide thin film,
Furthermore, a sensitizing layer made of a similar tellurium oxide thin film is laminated on the surface of this recording layer, and the recording layer side is made of a weak oxide with a relatively small degree of oxidation, and the sensitizing layer side is made of a weak oxide with a relatively low degree of oxidation. It has been found that the above object can be achieved by using a strong oxide with a higher degree of oxidation.

In other words, according to the findings of the present inventors, a weak Te oxide thin film has a sensitivity equivalent to that of simple Te as a recording layer, and has excellent stability and weather resistance. Weather resistance is further improved by laminating the sensitizing layer, and even when this laminate is bonded to another base material to form a recording medium, there is no reduction in sensitivity or variation in recording shape.

The present invention has been made based on the above findings, and more specifically, the optical recording material according to the present invention comprises a tellurium oxide represented by the general formula TeO (x is a positive real number) on a support. A recording layer made of It is characterized by

Usually, in the present invention, in the above general formula, 0<X
≦1.5, and 0.5≦y≦2.

In producing the optical recording material of the present invention as described above, the recording layer and the sensitizing layer can be easily produced by a reactive sputtering method.

Furthermore, in producing the optical recording material of the present invention, tellurium is evaporated onto a support by vacuum evaporation, and at the same time an ion beam made of an oxygen-containing gas is irradiated onto the support, the above-mentioned process is carried out. A recording layer and a sensitizing layer having such a composition can be produced, and in any case, an optical recording material can be produced at a relatively low cost by a simple and rapid method.

[Detailed description of the invention]

Hereinafter, the optical recording material according to the present invention will be explained in detail with reference to the accompanying drawings.

As shown in the cross-sectional view of FIG. 1, an optical recording material 1 according to an embodiment of the present invention has a recording layer 3 and a sensitizing layer 4 in this order on the surface of a support 2 (lower side in this figure). It has a laminated structure. In such an embodiment, information is recorded and read from the support (light-transmitting) 2 side as shown in the figure.

Therefore, although not shown, the sensitizing layer 4 and the recording layer 3 may be laminated in this order on the support 2, and in this case, information can be recorded and read from the recording layer side.

Furthermore, in the optical recording material of the present invention, a protective layer (not shown) made of synthetic resin or the like may be formed on the surface of the outermost sensitized layer 4.

Further, in the optical recording material of the present invention, as in the embodiment shown in FIG. 2, another base material 6 can be further laminated and integrated on the surface of the sensitized layer 4 via an adhesive layer 5. .

Each component will be explained below.

Support The support 2 supports the optical recording material and can be made of any conventionally known material. Furthermore, other recording means may be formed on this support 2 as necessary.

The material for the support 2 can be selected depending on the strength and flexibility depending on the purpose. Examples of plastics include polycarbonate, polyethylene terephthalate, polyester resin, epoxy resin, acrylic resin, and polychloride. Vinyl resin or polystyrene resin may be used, but ceramics such as glass may also be used. Further, in the case of the structure shown in FIG. 1, the support 2 needs to be transparent (including light transmittance) in order to transmit recording and reproducing beams. These materials for the support may be ones to which appropriate additives are added in advance depending on the intended use.

Recording layer and sensitized layer The recording layer 3 formed on the surface of the support 2 has the general formula TeO
(x is a positive real number) made of an oxide of Te. In general, X in the general formula preferably falls within the range of 0<x≦1.5. In this case, if X exceeds 1.5, the light reflectance and absorption rate will decrease, making it impossible to record information using a laser or the like.

On the other hand, the sensitizing layer 4 is made of an oxide of Te represented by the general formula TeO (y is a positive real number). y in the general formula is 0.5
The range of ≦y≦2 is preferable, and the above X(!:3/ is x<
There is a relationship y. In this case, if y is less than 0.5, the state will be close to that of metal Te, and no sensitizing effect will be obtained.
In severe cases, this is not preferable because it may cause a decrease in sensitivity.

In other words, Te oxide continuously changes its state depending on its oxidation state, from a state close to metallic Te with metallic luster to a state close to Te O2, which is transparent to visible light (light transmittance). Possible. Therefore, when looking at Te oxide as an optical recording material, it has a weak oxidation state that has metallic luster, sufficiently reflects the recording light, and has excellent energy absorption characteristics (that is, has excellent recording sensitivity and is easy to form pits), and a It can be broadly classified into strongly oxidized states that have excellent transparency and little reflection and absorption of recording light (that is, have no recording properties).

Furthermore, when looking at Te oxide from the standpoint of stability, it is considered that the state where the degree of oxidation is high < T e 02 is superior in stability; however, according to the findings of the present inventors,
Practically speaking, sufficiently good stability can be obtained if X of the oxide TeO is in a range of 0.3 or more. In this weakly oxidized state, an excellent effect can be obtained in terms of recording sensitivity, and the recording layer can exhibit excellent overall characteristics.

The thickness of the recording layer is preferably 100 to 1500A,
More preferably, the number is 300 to 700 people. If the thickness of the recording layer is less than 100 Å, the light reflectance is too small and is unsuitable, while if it exceeds 1500 Å, the sensitivity and recording shape will deteriorate.

On the other hand, the thickness of the sensitized layer is preferably in the range of 50 to 5000 Å, more preferably 200 to 100 OA. If the sensitizing layer is less than 50A, it is too thin and no good sensitizing effect can be obtained, while if it exceeds 5,000A, it is too thick and cracks are likely to occur, which is not preferable.

In the present invention, the sensitizing layer improves the recording sensitivity and reproduction sensitivity of the recording layer. That is, in the optical recording material of the present invention, when recording optical information, pits are formed in the recording layer using a laser beam or the like, and information is recorded.On the other hand, when reproducing the recorded information, light reflection at the pit-forming portion is used. Reading of recorded information is performed by detecting a difference in rates. Therefore, the sensitizing layer contributes to improving the sensitivity by further increasing the difference in reflectance from the recording layer, but it also has the following effects in addition to this.

(b) Protect the recording layer and improve the weather resistance and stability of the optical recording material.

(b) It has an extremely excellent effect in adjusting the shape of recording pits. That is, a recording pit is not generated inside or around the recording pit, and recording pits can be formed with smooth recording pits around the bit.

(c) For example, when the above-mentioned optical recording material is bonded and integrated with another substrate, such as a card base material, for the purpose of making a card, without this sensitizing layer, the sensitivity will drop significantly and the recorded shape will vary in size. Variations occur.

Therefore, the presence of the sensitizing layer is extremely effective in solving these problems, and the optical recording material of the present invention having the above structure is particularly suitable for forming a so-called sealed optical card. There is.

In addition, in the optical recording material of the present invention, the recording layer and the sensitizing layer are made of materials with the same compositional components and differ only in their compositional ratios (i.e., the ratio of Te and oxygen). It is also superior in that it can prevent undesirable reactions at the interface between the two layers, compared to the case where the two layers are used.

In other words, it is possible to minimize the occurrence of strain and stress due to migration of constituent elements and other physical and chemical interactions at the interface between both layers, or differences in stress at the interface, and to minimize the occurrence of physical, chemical, and mechanical As a result, a stable optical recording material can be obtained.

In the present invention, the recording layer and the sensitizing layer may be formed such that the composition ratio of both layers continuously changes at the boundary thereof.

In other words, in the optical recording material of the present invention, the Te10 ratio of the Te oxide constituting the recording layer and the Te oxide also constituting the sensitizing layer changes continuously at the interface between the two layers. It is sufficient that a layer substantially consisting of at least two types of weak oxide and strong oxide as described above is formed.

Thin film formation (1) The Te oxide thin film constituting the recording layer and sensitizing layer of the present invention is
It can be easily obtained by a reactive sputtering method. That is, a thin film having a desired composition ratio can be formed by performing sputtering using elemental Te as a target while discharging a mixed gas of oxygen and an inert gas.

Such a reactive sputtering method can be carried out according to a conventionally known method, and its details are disclosed, for example, in "Sputtering Phenomenon" (Kamehara Kanehara, University of Tokyo Press, 1984, pp. 120-132). has been done.

Formation of a Te oxide thin film by the above-mentioned reactive sputtering method can be performed using a normal sputtering device, but sputtering is performed with the atmosphere inside the device set to a mixed gas of argon and oxygen, and further Inside,
Modifications such as providing an oxygen jet port may be made in order to improve the oxygen reaction efficiency.

The relationship between the mixing ratio of inert gas and oxygen gas and the oxygen concentration in the thin film obtained is a qualitative relationship in which the amount of oxygen in the thin film increases as the oxygen content in the mixed gas increases. , the constant relationship depends on the structure of the sputtering apparatus used, the pumping speed, the pressure during sputtering, the gas introduction method, etc., so the general relationship differs depending on each apparatus.

However, once you start using one device and set the operating condition profile, the oxygen concentration in the thin film can be determined by the gas mixture ratio, so the reproducibility of thin film fabrication is good. . Therefore, the recording layer and the sensitizing layer can be produced almost continuously in the same apparatus by changing the gas mixture ratio.

The advantages of forming a thin film by reactive sputtering are as follows.

(1) The oxidation state of Te can be controlled to the desired state by changing the mixing ratio of inert gas and oxygen, and it is possible to form both the recording layer and the sensitizing layer using only one type of target. becomes. Generally, targets made of alloys or compounds are more difficult to manufacture and more expensive than single targets.

(2) The flow rate and mixing ratio of the introduced gas can be controlled very accurately to the container by using a device such as a mass flow controller, so the reproducibility of thin film production is excellent. On the other hand, when producing thin films of alloys or compounds by conventional vapor deposition methods, it is generally difficult to produce thin films with good composition ratio reproducibility.

(3) The film deposition rate is high and productivity is excellent.

When Te oxide is used as a target, the rate of deposition from the target is low and productivity is poor. On the other hand, 'C
1. According to the above-mentioned Noj method, single-doped Te is used as a target, so that high-speed, low-temperature, and short-time deposition is possible, and both productivity and quality can be improved.

(4) Ordinary sputtering equipment can be used as is.

Thin film formation (2) The recording layer and the sensitizing layer of the present invention are formed by evaporating Te onto a support using a vacuum evaporation method and simultaneously irradiating an ion beam made of an oxygen-containing gas onto the support. can also be produced.

The method and apparatus for producing a two-component thin film as described above are disclosed in Japanese Patent Application No. 61-53385, which the present inventor has already proposed. , can be adopted under different conditions.

The film forming conditions when applying the above method to the present invention are as follows.

(a) Conditions common to the formation of both the recording layer and the sensitizing layer Preliminary evacuation: 1O-5Torr Introduced gas: Film-forming rate of oxygen and inert gas Te: 1 to 50OA/sec Vacuum degree: 3X10-5 to lXl0−”Torr(
Outside this range, the operation of the ion gun becomes unstable) (b)
Operating conditions of the ion gun for forming the recording layer: Accelerating voltage 50 to 100 OV In this case, if it is less than 50 V, it is difficult to control the ion current, while if it exceeds 1,000 V, the sputtering effect increases and film formation becomes difficult.

Ion current density 10 to 300 μA/aj In this case, if it is less than 10 μA/cj, oxidation is insufficient and stability over time decreases, while if it exceeds 300 μA/cj, oxidation is excessive, resulting in a decrease in recording sensitivity.

Film thickness: 100 to 1,500 If it is less than 100, the reflectance is insufficient, and if it exceeds 1,500, the recording sensitivity will decrease.

(c) Formation of sensitized layer Ion gun operating conditions: Accelerating voltage 50 to 100 OV In this case, if it is less than 50 V, it is difficult to control the ion current, while if it exceeds 100 OV, the sputtering effect increases and film formation becomes difficult.

Ion current density: 200 to 1000 μA/cd In this case, if it is less than 200 μA/c, oxidation will be insufficient and the recording sensitivity will decrease, while if it exceeds 1000 μA/c, the support will suffer heat loss due to the ion current, which is not preferable. .

Film thickness: 50 to 5,000 people If it is less than 5 OA, the recording sensitivity will decrease, and if it exceeds 500 OA, the problem of peeling of the thin film will occur.

The above method of using ion beam irradiation and vapor deposition in combination has the following advantages.

(a) It is easy to control the composition of the desired thin film. That is, a thin film having a desired composition can be obtained simply by controlling the accelerating voltage and ion current of the ion gun to a desired state, resulting in extremely excellent controllability.

(b) Since the reactivity when forming oxides is high, thin film formation is performed at relatively low lH (below 100°C), so the transparent support is made of a relatively heat-resistant material such as plastic. A good thin film can be formed even if

(c) Since the film can be formed under high vacuum, the incorporation of impurities into the thin film can be prevented as much as possible, and therefore an optical recording material of excellent quality can be produced.

Modification As shown in FIG. 2, in the optical recording material 1 of the present invention, a base material 6 may be formed on the sensitizing layer 4 side with an adhesive layer 5 interposed therebetween. For this base material 6, a desired material can be selected depending on the use and the final target product. Furthermore, other recording means such as magnetic stripes, holograms, imprints, photographs, bar codes, and general printing may be formed on this base material 6 (or support 2).

The adhesive layer 5 joins and integrates the base material 6 and the sensitized layer 4, and the adhesive is selected in consideration of the materials above and below the adhesive surface. Specifically, it is preferable to use an adhesive that is of a type that cures under heating or at a temperature of 50° C. or lower and that provides a sufficiently good adhesive force between the upper and lower materials.

The embodiment shown in FIG. 3 is an example in which the transparent support 2 is composed of a tracking unevenness forming layer 2a, a transparent plate 2b, and a surface protection layer 2C. In this case, the surface protective layer 2C may not be formed. Further, a primer layer (not shown) may be provided between each of these layers in order to increase adhesive strength.

The tracking unevenness forming layer functions as a guide groove for tracking when recording and reading information, and its shape is as shown in Fig. 4, with fine unevenness or a matte finish that scatters light along the guide groove. It may be something that has been done.

The surface protective layer 2C is provided as the outermost layer and is preferably made of a material that has high hardness and has a lower light refractive index than the transparent plate 2c. By selecting such a material,
The recording and reproducing sensitivity can be further enhanced by the effect of preventing undesirable reflection of laser light during recording and reproducing.

Specifically, silicone-based, acrylic-based, melamine-based,
A cured resin obtained by curing polyurethane-based or epoxy-based resin may be used.

FIGS. 5 and 6 are examples in which the tracking unevenness forming layer is integrally provided in the transparent support in FIGS. 3 and 4, respectively.

In the embodiments of the optical recording material shown in FIGS. 3 to 6 described above, the recording layer and the sensitizing layer are sealed inside the laminate, and each layer is in close contact with each other.
It has excellent weather resistance against the external environment and is advantageous in terms of both improved stability over time and improved sensitivity.

Applications The optical recording material of the present invention can be used as flexible disks, cards, tapes, etc., and can be widely applied, for example, to the following applications.

(1) Financial distribution industry: cash cards, credit cards, prepaid cards.

(2) Medical and health industry; health certificates, medical records, medical cards,
emergency card.

(3) Entertainment industry: software media, membership cards, admission tickets, game machine control media, video game media, karaoke media.

(4) Transportation and travel industry; traveler cards, licenses, commuter passes,
passport.

(5) Publishing industry: electronic publishing.

(6) Information processing industry: external storage media for electronic machines, filing.

(7) Education industry: educational material programs, grade management cards, library crowd management and book management.

(8) Automotive industry: Maintenance recording media, operation management.

(9) F8: Program recording medium for MC5NC, robot, etc.

(10) Others: Building control, home control, ID cards, media for vending machines, shoe king cards, etc.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to the description of these Examples.

Example 1 Acrylic plate with fine tracking irregularities on its surface (
A recording layer (with a thickness of 500 mm) was deposited on the surface of the support by reactive sputtering.
TeO) was provided. In this case, Te with a purity of 99.99% was used as the target.

The above reactive sputtering was performed using 86% argon and 1% oxygen.
4% and a pressure of 5×10'Torr.

Subsequently, a sensitizing layer (TeO) was laminated to a thickness of 500 mm on the recording layer obtained above in an atmosphere of 58% argon, 42% oxygen, and a pressure of 5 x 10' Torr. did.

In each of the above layers, x-0, 7, yawl, 8.

Information was recorded on the obtained optical recording material.

High-speed, high-sensitivity recording of 1 μs or less could be performed using a laser beam of 830 nm and 5 mW.

In addition, the formed information bits have a good recording shape, and are approximately 1
No change in sensitivity or stability was observed even after leaving it for months.

On the surface of the sensitized layer of the optical recording material obtained as above,
Furthermore, a layer of 0.00 mm thick is applied via a two-component curing urethane thread pinching agent layer.
A 32 m+s vinyl chloride resin base material was bonded and integrated and molded into a card size to produce an optical card which is another embodiment of an optical recording material.

When I recorded information on this optical card, it turned out to be 830n.
High-speed, high-sensitivity recording of 3 ps or less could be performed using a laser beam of m s 5 rn W. Also, 60℃,
Even after being left in an atmosphere of 90% relative humidity for about 3 months, no change in sensitivity or stability was observed.

Comparative Test Example Support-F contains Te alone, a weak oxide of Te (TeO)T
A 0.5 thin film of a strong oxide (T e Ot,s ) of
When the battery was left in 90% relative humidity), the following results were obtained.

Recording layer Sensitivity Weather resistance Te Good Reflectance decreases within 100 hours Te weak oxide Good No change for over 500 hours Te strong oxide Not available As mentioned in 2 above, recording layers made of Te and Te weak oxide exhibit good recording sensitivity. Ta. However, in weathering tests, the Te thin film showed a significant decrease in reflectance within about 100 hours, after which the film became completely matte. On the other hand, Te
A recording layer made of a strong oxide had excellent weather resistance, but information could not be written on it.

Example 2 A recording layer and a sensitizing layer were formed on a PMMA support having a thickness of 0.61 mm by the following method.

Inside the vacuum evaporation equipment where the thermionic impact type ion gun is installed
Preliminarily evacuate to a vacuum level of 0'Torr or less, then introduce oxygen gas into the device to increase the vacuum level to 8X 10'Torr.
rl: Retained.

Next, vacuum evaporation of Te onto the support and ion beam irradiation were performed simultaneously.

The film forming conditions are as follows.

Ion gun: Acceleration voltage 500V Oxygen ion current density on substrate 50μA/c Te
Film forming speed: 10 persons/second Film thickness: 500 persons Next, oxygen gas was introduced into the apparatus to maintain the degree of vacuum within the apparatus at 1.0XIO-'Torr. A sensitized layer was subsequently formed on the surface of the layer. The film forming conditions at this time are as follows.

Ion gun: Acceleration voltage 500V Oxygen ion current density on substrate 500μA/cdTe
Film forming rate: 10 A/sec Film thickness: 1000 people The composition of each thin film obtained was that the recording layer was TeOo, 5, and the sensitizing layer was Teal, 2.

The information recording sensitivity and stability of the thus obtained optical recording material of the present invention were examined in the same manner as in Example 1, and almost the same results as in Example 1 were obtained.

〔Effect of the invention〕

The optical recording material according to the present invention has a recording layer and a sensitizing layer made of tellurium oxide thin films having different degrees of oxidation, which are laminated on a support, so that it has excellent information recording sensitivity and weather resistance. It has characteristics.

Furthermore, the optical recording material of the present invention has excellent productivity and quality because the recording layer and the sensitizing layer can be produced quickly and with good reproducibility by a reactive sputtering method or a vapor deposition method using ion beam irradiation. It also has excellent effects in terms of improvement and reduction of manufacturing costs.

[Brief explanation of drawings]

1 to 6 are cross-sectional views of optical recording materials according to embodiments of the present invention, respectively. 2... Support, 3... Recording layer, 4... Sensitized layer, 6
···Base material. Applicant's agent Mr. Sato Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] 1. A recording layer made of an oxide of tellurium represented by the general formula TeO_x (x is a positive real number) on a support;
A sensitizing layer made of tellurium oxide represented by O_y (y is a positive real number) is laminated, and in the general formula x
An optical recording material characterized by having the relationship <y. 2. The optical recording material according to claim 1, wherein the support is made of a transparent material, and a recording layer and a sensitizing layer are formed in this order on the support. 3. In the above general formula, 0<x≦1.5, 0.5≦y
Optical recording material according to claim 1 or 2, characterized in that ≦2. 4. The optical recording material according to claim 1 or 3, characterized in that a base material is further bonded and integrated to the surface of the sensitized layer via an adhesive layer. 5. The optical recording material according to any one of claims 1 to 4, wherein the recording layer and the sensitizing layer are produced by a reactive sputtering method. 6. The recording layer and the sensitizing layer are prepared by evaporating tellurium onto the support by vacuum evaporation and simultaneously irradiating the support with an ion beam made of an oxygen-containing gas. An optical recording material according to any one of claims 1 to 4. 7. Claim 1, characterized in that a tracking layer is formed on the recording layer side of the transparent support.
The optical recording material according to any one of Items 1 to 6.