WO2003028020A1

WO2003028020A1 - Optical recording medium

Info

Publication number: WO2003028020A1
Application number: PCT/JP2002/009736
Authority: WO
Inventors: Naoki Hayashida; Hideki Hirata
Original assignee: Tdk Corporation
Priority date: 2001-09-26
Filing date: 2002-09-20
Publication date: 2003-04-03

Abstract

An optical recording medium having friction characteristics (friction force and/or friction coefficient) reduced on the surface of an optical recording medium, especially on the surface of a light transmitting layer or a hard coat layer. An optical recording medium which comprises a substrate (11), a recording layer (13) provided on the substrate (11), and a hard coat layer (15) provided on the recording layer (13), and which records/reproduces data by applying a laser beam onto the recording layer (13) via the hard coat layer (15), wherein a friction coefficient measured is up to 1.5 when a planar weight of 5-50 g/cm2 is applied to the surface of the hard coat layer (15) via a self-adhesive type long-fiber nonwoven fabric mainly containing cellulose while the optical recording medium is turned at 50-3000 rpm. Accordingly, a flaw on the surface of a translucent substrate serving as a light incident surface can be effectively prevented.

Description

Description Optical recording media Technical field

The present invention relates to an optical recording medium, and more particularly, to an optical recording medium in which generation of a scratch on a light incident surface is effectively prevented. Conventional technology

In recent years, optical recording media such as CD and DVD have been widely used as recording media for recording large volumes of digital data. Generally, a read-only optical recording medium has a light-transmitting layer (light-transmitting substrate), a reflective layer, and a protective layer laminated in this order from the light incident surface side, and a writable optical recording medium has a light incident surface side. Each layer is laminated in the order of a light transmitting layer (light transmitting substrate), a recording layer, a reflective layer, and a protective layer. In a read-only optical recording medium, the reflective layer is an information recording layer, and in a writable optical recording medium, the recording layer is an information recording layer. In any type of optical recording medium, when reading data, a laser beam set to a reproducing power is irradiated from the light transmitting layer side, and the reflected light is detected. In addition, when writing data to a writable optical recording medium, a laser beam set to a recording power is irradiated from the light transmitting layer side, and the heat energy and Z or the light energy cause the chemical state of the recording layer to change. Alternatively, the physical state is changed based on the data to be recorded.

Here, the laser beam applied to the optical recording medium is focused by an optical system such that a beam spot having a predetermined diameter is formed in the reflection layer or the recording layer. For this reason, if there is a scratch on the surface of the light transmitting layer, the beam spot is not formed correctly, and a reading error or a writing error may occur. As a method for preventing the generation of such scratches, a hard coat layer having high hardness is conventionally provided on the surface of the light transmitting layer. Methods are known.

By the way, in recent years, the numerical aperture (NA) of an objective lens for focusing a laser beam used for recording / reproducing has been increased to 0.7 or more, for example, to about 0.85, and the laser beam used for recording / reproducing has been increased. Attempts have been made to reduce the focused spot diameter of the laser beam by shortening the wavelength I to about 400 nm, thereby recording large volumes of digital data. However, since the allowance of the warp or tilt of the optical recording medium, that is, the tilt margin becomes small, the thickness of the light transmitting layer (light transmitting substrate) needs to be reduced in order to secure a sufficient tilt margin. For example, when NA = 0.85 and λ = 400 η ιη, the thickness of the light transmitting layer should be reduced to about 100 μm to secure a sufficient tilt margin. Required to That.

When the NA is increased, the working distance (working distance) between the objective lens and the surface of the optical recording medium is reduced. For example, when NA is set to about 0.85, the working distance is 10 mm. It is about 0 μm, which is much narrower than before.

However, if the working-distance becomes very narrow, the possibility of contact between the surface of the optical recording medium and the objective lens 支持 the supporting body during the rotation of the optical recording medium becomes very high. If such contact occurs during the rotation of the medium, there is a possibility that the surface of the light transmitting layer of the optical recording medium may be seriously damaged. The occurrence of scratches due to such contact can be suppressed to some extent by providing the above-described hard coat layer. However, when the light transmitting layer is thinned to about 100 / im, the recording noise on the surface of the light transmitting layer is reduced. The focusing diameter of the laser beam for reproduction is also extremely small, so even if there is a scratch or dirt of a size that would not cause a reading error or a writing error with a conventional optical recording medium, a reading error or a writing error can easily occur. Will be. For this reason, simply increasing the hardness of the hard coat layer is not enough to reduce scratches caused by contact during rotation. Disclosure of the invention

In order to effectively reduce scratches on the surface of the optical recording medium caused by contact during rotation, the present inventors not only increase the hardness of the hard coat layer but also reduce the friction coefficient of the hard coat layer surface. Came to the conclusion that was effective.

Accordingly, an object of the present invention is to provide an optical recording medium having improved friction characteristics on the surface of an optical recording medium, particularly on the surface of a light transmitting layer or a hard coat layer, that is, reduced frictional force and z or friction coefficient. To provide. Another object of the present invention is to provide an optical recording medium of a type for recording and / or reproducing data without physical contact, wherein the optical recording medium has an improved friction characteristic of a light incident surface. It is to be.

Furthermore, if the user frequently wipes off dust and dirt attached to the surface of the optical recording medium with a nonwoven fabric or tissue paper, or frequently with a rag containing water or an aqueous detergent solution, the friction coefficient of the surface of the hard coat layer is reduced. It has been confirmed by experiments of the present inventors that the value tends to increase in accordance with this. Therefore, even if the friction coefficient of the hard coat layer surface is sufficiently low in the initial state, if the friction coefficient of the hard coat layer surface is extremely increased each time such a wiping operation is performed by the user, the user is frequently asked. If, after the wiping operation, the contact with the above-described objective lens or the support supporting the objective lens occurs, the surface of the light incident surface of the optical recording medium may still be fatally damaged.

In order to solve such a problem, it is effective not only to reduce the friction coefficient on the surface of the hard coat layer, but also to increase its durability.

Therefore, still another object of the present invention is to provide an optical recording medium having high durability of friction characteristics (frictional force and Z or coefficient of friction) on the surface of the optical recording medium, particularly on the surface of the light transmitting layer or the hard coat layer. It is.

Still another object of the present invention is to provide an optical recording medium of a type for recording / reproducing data without physical contact, wherein the optical recording medium has a friction characteristic of a light incident surface. To provide an optical recording medium having high durability.

As described above, in order to effectively reduce scratches on the surface of the optical recording medium caused by contact with the objective lens and the support that supports the objective lens during rotation of the optical recording medium, the present invention is intended to reduce the surface damage of the optical recording medium. An object of the present invention is to provide an optical recording medium in which the friction coefficient is reduced to a predetermined value or less, based on the idea that it is effective to reduce the friction coefficient and reduce damage at the time of contact.

An object of the present invention is to provide an optical recording medium having at least a light-transmissive substrate, wherein data is recorded, recorded, or reproduced by irradiating a laser beam through the light-transmissive substrate. While rotating the recording medium at a rotation speed of 50 to 300 rpm, a surface of the light-transmitting substrate was passed through a self-adhesive long-fiber nonwoven fabric containing cellulose as a main component at 5 to 50 g / g. This is achieved by an optical recording medium characterized in that the coefficient of friction measured by applying a planar load of cm ₂ is 1.5 or less.

According to the present invention, since the coefficient of friction of the surface of the light-transmitting substrate is suppressed to 1.5 or less, generation of scratches on the surface of the light-transmitting substrate, which is the light incident surface, is effectively prevented. .

Further, in order to effectively reduce scratches on the surface of the optical recording medium caused by contact with the objective lens and the support supporting the objective lens during rotation of the optical recording medium, the present invention provides a friction coefficient of the surface of the optical recording medium. Not only to reduce the damage at the time of contact, but also to maintain the friction coefficient sufficiently high, based on the idea that it is effective to maintain the friction coefficient, that is, to reduce the friction coefficient. An object of the present invention is to provide an optical recording medium in which the rate of increase is suppressed to a predetermined value or less.

An object of the present invention is to provide an optical recording medium having at least a light-transmitting substrate, and recording / reproducing data by irradiating a laser beam through the light-transmitting substrate, This is achieved by an optical recording medium characterized in that the rate of increase in the coefficient of friction with respect to 100 slidings on the surface of the substrate is not more than 0.03. According to the present invention, since the rate of increase of the coefficient of friction on the surface of the light-transmitting substrate is suppressed to not more than 0.03, the user can remove dust and dirt adhering to the surface of the optical recording medium by using a nonwoven fabric or tissue paper. Even if it is frequently wiped with a rag containing water or a detergent aqueous solution, the low coefficient of friction is effectively maintained. Therefore, according to the present invention, it is possible to provide a highly reliable optical recording medium in which the light incident surface of the optical recording medium is not easily damaged for a long period of time.

In a preferred embodiment of the present invention, the friction coefficient is a value when the rotation speed of the optical recording medium is set at 100 to 150 rpm.

In a preferred embodiment of the present invention, the surface of the translucent substrate has a friction coefficient of 1.0 or less.

According to a further preferred embodiment of the present invention, since the friction coefficient of the surface of the light-transmitting substrate is suppressed to 1.0 or less, generation of scratches on the surface of the light-transmitting substrate, which is the light incident surface, is reduced. More effectively prevented.

In a further preferred aspect of the present invention, the surface of the light-transmitting substrate has a coefficient of friction of 0.8 or less.

According to a further preferred embodiment of the present invention, since the friction coefficient of the surface of the light-transmitting substrate is suppressed to 0.8 or less, generation of scratches on the surface of the light-transmitting substrate, which is the light incident surface, is reduced. It is even more effectively prevented.

In a further preferred aspect of the present invention, the light-transmitting substrate comprises a light-transmitting layer and a hard coat layer provided on the surface thereof.

In a further preferred embodiment of the present invention, the light transmitting layer has a thickness of 5 to 30 O / zm.

In a further preferred embodiment of the present invention, the hard coat layer contains a lubricant.

In a further preferred embodiment of the present invention, the lubricant is a silicone-based lubricant, a fluorine-based lubricant or a fatty acid ester-based lubricant. In a further preferred embodiment of the present invention, the content of the lubricant is 0.1 to 5.0% by mass.

In a further preferred aspect of the present invention, the coefficient of friction is a value in a region where the cumulative number of rotations of the optical recording medium is 100 or less. In a further preferred aspect of the present invention, the friction coefficient is a value at the time when the cumulative rotation speed of the optical recording medium is 100 times. In a further preferred aspect of the present invention, the coefficient of friction is a value at the time when the cumulative rotation speed of the optical recording medium is 100,000 times. In a further preferred embodiment of the present invention, the coefficient of friction is a value after storage in an environment at a temperature of 80 ° C. and a relative humidity of 5% or less for 100 to 100 hours.

In another preferred embodiment of the present invention, the rate of increase is not more than 0.01.

According to another preferred embodiment of the present invention, the low coefficient of friction is maintained more effectively because the rate of increase is not more than .0.01.

In another more preferred embodiment of the present invention, the increase rate is 0.007 or less.

According to another more preferred embodiment of the present invention, the low coefficient of friction is maintained more effectively because the rate of increase is less than 0.007.

In another more preferred embodiment of the present invention, the rate of increase is not more than 0.002.

According to another more preferred embodiment of the invention, the low coefficient of friction is maintained very effectively since the rate of increase is less than 0.002. In another more preferred embodiment of the present invention, the increase rate is a value in a region where the number of times of sliding is less than 100 times.

In another more preferred embodiment of the present invention, the increase rate is a value in a region where the number of times of sliding is 100 or more.

In another more preferred embodiment of the present invention, the increase rate is: This is a value measured by bringing a measuring member into planar contact with the surface of the translucent substrate and detecting a tensile force generated on the measuring member.

In another more preferred embodiment of the present invention, the rate of increase is such that, while rotating the optical recording medium at a rotation speed of 50 to 300 rpm, cellulose as a main component on the surface of the transparent substrate. It is a value measured by applying a planar load of 5 to 50 g / cm ₂ through a thin film of a self-adhesive long fiber nonwoven fabric.

In another more preferred embodiment of the present invention, the increase rate is a value measured by setting the rotation speed of the optical recording medium to 100 to 150 rpm. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view schematically showing a structure of an optical recording medium 10 according to a preferred embodiment of the present invention.

FIG. 2 is a diagram for explaining a method of measuring the friction coefficient of the surface of the hard coat layer 15.

FIG. 3 is a graph showing the measurement results of the friction coefficient of Sample # 1 to Sample # 5.

FIG. 4 is a graph showing the measurement results of the friction coefficient of Sample # 6 to Sample # 10.

FIG. 5 is a graph showing the measurement results of the friction coefficients of Sample # 11 to Sample # 15.

Figure 6 is a graph showing the measurement results of the friction coefficients of samples # 1, # 3, # 5, # 6, # 8, # 10, # 11, # 13, and # 15 after the storage test. is there. Embodiment of the Invention

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. This will be described in detail.

FIG. 1 is a sectional view schematically showing the structure of an optical recording medium 10 according to the present embodiment.

As shown in FIG. 1, the optical recording medium 10 according to the present embodiment includes a substrate 11 having a thickness of about 1.1 mm, and a reflective layer 12 having a thickness of 70 to 130 nm. A recording layer 13 having a thickness of 100 to 250 nm, a light transmitting layer 14 having a thickness force S 5 to 300 μm, and a thickness force 0.5 to: L 0 / m Of the hard coat layer 15. Further, a hole 16 is provided in the center of the optical recording medium 10. The substrate 11 is made of polycarbonate, and the reflection layer 12 is made of an alloy mainly containing silver. Further, the recording layer 13 has a multilayer structure in which a dielectric film is sandwiched above and below a phase change film on which data is actually recorded. Further, the light transmitting layer 14 and the hard coat layer 15 are made of an ultraviolet curable resin or a resin sheet such as polycarbonate or polyolefin. When reading data from the optical recording medium 10 having such a structure, a laser beam set to the reproduction power is irradiated from the hard coat layer 15 side, and the reflected light amount difference is detected. . When writing data to the optical recording medium 10, a laser beam set to a recording power is irradiated from the hard coat layer 15 side, and thereby the state of the recording layer 13 (the crystal structure of the phase change film) To change. In this specification, both or one of the light transmitting layer 14 and the hard coat layer 15 may be referred to as a “light transmitting substrate”.

In the optical recording medium 10 according to the present embodiment, the coefficient of friction of the surface of the hard coat layer 15 is 1.5 or less, preferably 1.0 or less, and more preferably 0.8 or less. . Furthermore, when the surface of the hard coat layer 15 is slid with nonwoven fabric or tissue paper, the coefficient of friction of the surface of the hard coat layer 15 that increases with 100 times of sliding is referred to as “increase rate”. When defined, in the optical recording medium 10 according to the present embodiment, the rate of increase is not more than 0.03, preferably not more than 0.01, and more preferably not more than 0.007. And particularly preferably 0.02 or less. In order to obtain such values as the coefficient of friction of the surface of the hard coat layer 15 and the rate of increase thereof, it is effective to include a lubricant in the hard coat layer 15. As the lubricant, it is preferable to select a silicone-based lubricant, a fluorine-based lubricant, or a fatty acid ester-based lubricant, and the content thereof is preferably about 0.1 to 5.0% by mass. This is because if the lubricant content is less than 0.1% by mass, a sufficient lubricating effect cannot be obtained, and even if the lubricant content exceeds 5.0% by mass, the lubricating effect can be further enhanced. This is because it can cause stickiness. Further, in the optical recording medium 10 according to the present embodiment, after being stored in a high-temperature environment for a long time, specifically, the temperature is 60 to 90 degrees and the relative humidity is 30% or less, preferably 5% or less. It is preferable that the friction coefficient of the surface of the hard coat layer 15 has the above value even after storage for 100 to 100 hours in an environment of not more than 100%. Further, even after storage for a long time in a high-temperature and high-humidity environment, the friction coefficient of the surface of the hard coat layer 15 preferably has the above value. Next, a method for measuring the friction coefficient of the surface of the hard coat layer 15 will be described.

FIG. 2 is a view for explaining a method of measuring the coefficient of friction of the surface of the hard coat layer 15 and the rate of increase thereof.

As shown in FIG. 2, in the measurement of the coefficient of friction of the surface of the hard coat layer 15 and the rate of increase thereof, the rotation mechanism 1 for rotating the optical recording medium 10 according to the present embodiment and the measurement member The measuring thin film piece 2, a weight 3 for pressing the measuring thin film piece 2 against the surface of the optical recording medium to be measured, and a transducer 4 for detecting the tensile force generated on the measuring thin film piece 2 Used.

The measuring thin film piece 2 is used to convert a frictional force generated between the rotating optical recording medium surface (here, the surface of the hard coat layer 15) into a tensile force, and is particularly limited. However, since the difference in surface properties of each optical recording medium can be effectively determined, the material is fiber It is preferably an aggregate, particularly preferably a self-adhesive long-fiber nonwoven fabric containing an organic substance as a main component and formed by spin-bonding, for example, a cellulose as a main component.

The weight 3 has a columnar shape with a flat bottom surface, and a cushioning material 5 is provided on the bottom surface portion so that the load on the thin film piece 2 for measurement is evenly distributed in a plane. Although not particularly limited, it is preferable to use poly-urethane, silicone rubber, or the like as the material of the cushioning material. The bottom area of the weight 3 is preferably 0.5 mm ² to 900 mm ² , and the load on the thin film piece 2 for measurement is 0.5 g / cm ² to 50 g Z cm ² . And are preferred.

In measuring the frictional characteristics, first, the optical recording medium 10 according to the present embodiment is placed on a rotating table (not shown) of a measuring device with the hard coat layer 15 facing upward, The thin film piece for measurement 2 and the weight 3 are placed on the surface of the optical recording medium 10. In this state, the rotation mechanism 1 is operated, and the optical recording medium 10 is rotated at 50 to 300 rpm, preferably at 100 to 150 rpm. FIG. 2 shows such a state. At this time, the frictional force generated between the surface of the optical recording medium 10 and the measuring thin film piece 2 loaded by the weight 3 pulls the measuring thin film piece 2 in the rotation direction of the optical recording medium 10. . The tensile force is converted into an electric signal by the transducer 4, whereby it is possible to specify the friction characteristics of the surface of the optical recording medium 10, that is, the friction force and / or the friction coefficient.

The measurement of the friction characteristics of the surface of the optical recording medium 10 by such a method is performed by measuring the friction characteristics of the surface of the MD (mini disk), which is a magnetic field modulation type optical recording medium, on the side of the magnetic field modulation head other than the optical pickup side. Compared to the case of using a device for measuring the temperature, it has the feature that the reproducibility is better because it is less susceptible to dust and dust penetration. Here, the device for measuring the friction characteristics of the surface of the MD (mini disk) is used to measure the friction force and / or coefficient of friction on the surface on which the magnetic field modulation head contacts. This is the equipment used, and the measurement using such equipment is described in Paragraph 20 of the Annex of the Mini Disc System Standard (Rainbow Book). Such a measuring device is not suitable for measuring the frictional force and / or the coefficient of friction on the light incident surface of a type of optical recording medium in which data is recorded and reproduced without physical contact.

In the optical recording medium 10 according to the present embodiment, the friction coefficient of the surface of the hard coat layer 15 measured using the method described above is set to 1.5 or less as described above. Furthermore, in the optical recording medium 10 according to the present embodiment, the friction coefficient of the surface of the hard coat layer 15 and the increase rate thereof measured using the above-described method are not more than 0.03 as described above. Is set to For this reason, even if the user frequently wipes the dust and dirt attached to the surface of the hard coat layer 15 with a nonwoven fabric or tissue paper, or with a rag containing water or a detergent solution, However, the increase in the coefficient of friction on the surface of the hard coat layer 15 can be suppressed to a small level. For this reason, when recording / reproducing data on the optical recording medium 10, a high NA lens having a NA of about 0.85 is used, and the objective lens and the surface of the optical recording medium 10 (the hard coat layer 15) are used. Even when the working distance (peaking distance) is set to about 100 μm, the surface of the optical recording medium 10 (the hard coat layer 15) and the objective Since the occurrence of scratches due to contact with the lens and the support that supports the lens is suppressed, the reliability can be significantly increased.

In particular, if the friction coefficient of the surface of the hard coat layer 15 is set to 1.0 or less, the occurrence of such scratches can be more effectively suppressed, and the friction coefficient of the surface of the hard coat layer 15 can be further reduced. Is set to 0.8 or less, the occurrence of such scratches can be more effectively suppressed.

Also, if the rate of increase of the coefficient of friction on the surface of the hard coat layer 15 is set to 0.01 or less, the increase in the coefficient of friction on the surface of the hard coat layer 15 can be suppressed to a smaller value, and the Do frequent wiping work, Even when the user performs the wiping operation with a waste cloth containing water or an aqueous solution of detergent, the occurrence of such scratches can be effectively suppressed. Furthermore, if the rate of increase in the coefficient of friction of the surface of the hard coat layer 15 is set to 0.07 or less, the increase in the coefficient of friction of the surface of the hard coat layer 15 can be further reduced. Even if the user performs the wiping work more frequently and even if the user performs the wiping work using a waste containing low molecular weight alcohol such as methanol / ethanol, the generation of such scratches can be effectively prevented. Can be suppressed. Furthermore, if the rate of increase in the coefficient of friction of the surface of the hard coat layer 15 is set to 0.002 or less, the increase in the coefficient of friction of the surface of the hard coat layer 15 can be suppressed to an extremely small value. However, even when the wiping operation is performed very frequently, or when the user performs the wiping operation using a waste cloth containing various solvents, the generation of such scratches can be effectively suppressed.

As described above, in the optical recording medium 10 according to the present embodiment, since the coefficient of friction of the hard coat layer 15 serving as the light incident surface is kept low, the surface of the light incident surface is damaged. It has the characteristic of being difficult. For this reason, in recording and reproducing or reproducing data on the optical recording medium 10, a high NA lens having a NA of about 0.85 is used, and the objective lens and the surface of the optical recording medium 10 (the hard coat layer 15) are used. ), The surface (hard coat layer 15) of the optical recording medium 10 during rotation of the optical recording medium 10 even when the working distance (peaking distance) is set to about 100 m. Since the occurrence of scratches caused by contact between the object and the objective lens or the support that supports the objective lens is suppressed, the reliability can be greatly increased.

In addition, in the optical recording medium 10 according to the present embodiment, since the rate of increase in the coefficient of friction of the hard coat layer 15 serving as the light incident surface is suppressed to a low level, the user can control the surface of the hard coat layer 15. Even if the dust and dirt adhering to the surface are frequently wiped off with a nonwoven fabric or tissue paper, or frequently wiped with a rag containing water or detergent aqueous solution, The increase in the coefficient of friction on the surface of the layer 15 can be kept small. Therefore, in the data recording / reproducing Z on the optical recording medium 10, a high NA lens of about NA = 0.85 is used, and the working distance between the objective lens and the surface of the optical recording medium 10 (hard coat layer 15). When the (working distance) is set to about 100 μm, the user frequently performs wiping work, and then the surface (hard coat layer) of the optical recording medium 10 during rotation of the optical recording medium 10. Even if contact occurs between the 15) and the objective lens or the support that supports the objective lens, the occurrence of scratches due to this is suppressed, so that the reliability can be greatly increased. .

The present invention is not limited to the above embodiments, and various changes can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say, there is.

For example, the structure of the optical recording medium 10 according to the above embodiment is an example of an optical recording medium to which the present invention is suitably applied, and the structure of the optical recording medium to which the present invention is applied is limited to this. Not something. Therefore, the optical recording medium according to the present invention may be a read-only optical recording medium. Furthermore, the optical recording medium according to the present invention may be a magnetic field modulation type optical recording medium such as a magneto-optical recording medium. In this case, the optical recording medium is not on the side where the magnetic head is in contact, The friction coefficient of the incident surface of the recording / reproducing laser beam is set to 1.5 or less, and / or the increase rate of the friction coefficient of the recording / reproducing laser beam incident surface is set to 0.03 or less. .

However, the effect of suppressing the generation of scratches due to the reduction of the friction coefficient of the light incident surface is remarkable when contact occurs with the objective lens and the support supporting the objective lens. It is particularly suitable for an optical recording medium in which the light transmitting layer 14 is thinned to about 5 to 300 m with the increase in NA of the objective lens.

Further, in the measurement of the friction coefficient of the optical recording medium 10 according to the above embodiment, the weight 3 having a flat bottom is used, so that the surface of the optical recording medium and the thin film piece 2 for measurement are planarly arranged. Contact with even load However, any method may be used to apply a load to the measuring thin film piece 2 as long as they can be brought into contact with each other by applying a uniform load in a plane. Also, instead of the thin film piece for measurement, a measuring member having a sufficient weight to perform effective measurement is used, and the optical recording medium 10 is used by the own weight of the measuring member without using the weight 3. Friction with the surface may be obtained.

Furthermore, in the measurement of the friction coefficient of the optical recording medium 10 according to the above embodiment, the weight 3 having a cylindrical shape is used, but the weight 3 has a cylindrical shape as long as the bottom surface is flat. It is not mandatory to be Example

[Example 1]

The friction coefficient of the surface of 15 optical recording media (sample # 1 to sample # 15) on which different hard coat layers were formed was measured using the above-described friction characteristic measuring method.

In this measurement, a nonwoven fabric (Bencott Lint Free CT-18, manufactured by Asahi Kasei Corporation) having a length and a width of 10 Omm and 25 mm, respectively, was used as the thin film piece 2 for measurement. Here, the length of the thin film piece for measurement 2 is the direction in which the tensile force acts, and in FIG. The weight 3 was 2 Omm in diameter and 31 g in weight. The weight 3 was placed such that its center was located at a distance of 4 O mm from the center of the optical recording medium. Under such conditions, the rotational speed of the optical recording medium by the rotating mechanism 1 was set to 670 rpm, and the friction coefficient of each optical recording medium was measured.

Here, as the 15 optical recording media (sample # 1 to sample # 15) to be measured, all of the hard coat layers 15 are ultraviolet curable resins (Nippon Kayaku Co., Ltd., HOD An optical recording medium was prepared, which was composed of -3200) and contained different types and amounts of lubricant added to the ultraviolet-curable resin. Table 1 shows the type and amount of lubricant contained in the hard coat layer 15 of each sample. Also, in all samples, The thickness of the hard coat layer was 3.

FIG. 3 is a graph showing the measurement results of the friction coefficient of Sample # 1 to Sample # 5, FIG. 4 is a graph showing the measurement results of the friction coefficient of Sample # 6 to Sample # 10, and FIG. 19 is a graph showing measurement results of friction coefficients of Samples # 11 to # 15. 3 to 5, the vertical axis represents the friction coefficient, and the horizontal axis represents the cumulative rotation speed of the optical recording medium. 3 to 5, it can be seen that the larger the amount of the lubricant contained in the hard coat layer 15, the lower the friction coefficient.

Further, referring to FIGS. 3 to 5, it can be confirmed that the friction coefficient in the initial state (the cumulative number of revolutions is 100 or less) is 0.8 or less in each of the samples. The friction coefficient in the initial state (cumulative rotation speed: 100 times or less) means the friction coefficient of the surface of the hard coat layer 15 in a state immediately after production of each sample (in a new state). Therefore, it can be seen that the friction coefficient of the surface of the hard coat layer 15 in the state immediately after manufacture (in a new state) is very low (0.8 or less) in each sample.

Further, referring to FIGS. 3 to 5, the content of the lubricant is 1.0% by weight. For samples # 3, # 4, # 5, # 8, # 9, # 10, # 13, # 14, and # 15 that are more than sample # 1 coefficient has a 0.8 or less, 1% or 0.5 wt ^_0/0 0. content of the lubricant, # 2, # 6, # 7, # 1 1, # With regard to 12, it can be confirmed that the friction coefficient at the time when the cumulative number of revolutions was 100 000 was 1.0 or less. In each of the samples, the hard coat layer 15 shows that the friction coefficient at the time when the cumulative number of revolutions was 1000 times was higher than the friction coefficient in the initial state (cumulative number of revolutions = 100 times or less). This is because the lubricant used was wiped off by the thin film piece 2 for measurement. In other words, the friction coefficient at the time when the cumulative number of rotations is 100 times is defined as the value after the user frequently wipes off dust and dirt attached to the surface of the light incident surface of the optical recording medium with a nonwoven fabric or tissue paper. Means the coefficient of friction of the surface of the hard coat layer 15. Therefore, the coefficient of friction of the surface of the hard coat layer 15 after the user frequently wipes off dust and dirt attached to the surface of the light incident surface of the optical recording medium with a nonwoven fabric, tissue paper, or the like, depends on the lubricant content. For samples # 3, # 4, # 5, # 8, # 9, # 10, # 13, # 14, and # 15, whose sample content is 1.0% by weight or more, the sample is very low (0.8 below), the sample # 1 content of the lubricant is 0.1 wt ⁰ Zo or 0.5 wt ^_0/0, # 2, # 6, # 7, # 1 1, sufficiently lower for the # 1 2 (1.0 or less). Further, referring to FIGS. 3 to 5, samples # 4, # 5, # 9, # 10, # 14, and # 15 having a lubricant content of 3.0% by weight or more are described. The samples # 2 and # have a coefficient of friction of 0.8 or less at the time when the cumulative number of revolutions is 100,000 and the lubricant content is 0.5% by mass or 1.0% by mass. With respect to 3, # 7, # 8, # 12, and # 13, it can be confirmed that the friction coefficient at the time when the cumulative rotation speed is 1,000,000 times is 1.0 or less. In addition, it can be confirmed that the friction coefficient of all the samples at the time when the cumulative number of revolutions is around 100,000 times is 1.5 or less. Here, the accumulated number of rotations is 100 000 times The coefficient of friction at or near that point means that the user very often wipes off dust and dirt attached to the surface of the light incident surface of the optical recording medium with a nonwoven fabric or tissue paper, or removes water or detergent aqueous solution. It means the coefficient of friction of the surface of the hard coat layer 15 after frequent wiping with the contained waste cloth. Therefore, the coefficient of friction of the surface of the hard coat layer 15 after the user frequently wipes off dust and dirt attached to the surface of the light incident surface of the optical recording medium with a nonwoven fabric, tissue paper, or the like contains the lubricant. sample # 4 quantities 3. is 0 wt ^_0/0 or more, # 5, # 9, # 1 0, # 1 4, # 1 5 very low for (0. 8 or less), the content of the lubricant There 0.5 mass ^_0/0 or 1. 0 wt ^_0/0 is a sample # 2, # 3, # 7, # 8, # 1 2, for the # 1 3 lower to + min (1.0 or less) However, it can be seen that each sample is suppressed to some extent (1.5 or less).

Furthermore, as shown in FIGS. 3 to 5, it can be seen that the friction coefficient of each sample increases as the cumulative rotation speed increases. This is partly because the lubricant contained in the hard coat layer i5 was wiped off by the thin film piece 2 for measurement. From FIG. 3, it can be seen that the larger the amount of the lubricant contained in the hard coat layer 15, the lower the rate of increase in the coefficient of friction.

Also, referring to FIGS. 3 to 5, for all samples, the rate of increase is high in the region where the cumulative rotation speed is less than 100 times, and increases in the region where the cumulative rotation speed is 100 times or more. The rate is low. This is considered to be because more stable measurement is performed in the region where the cumulative rotation speed is 100 or more times. Therefore, the stable increase rate evaluation is preferably performed in the region where the cumulative rotation speed is 100 or more times, and is performed in the region where the cumulative rotation speed is 100 to 800 times. More preferably, it is particularly preferable to perform the operation in the region where the cumulative number of rotations is from 2000 to 600. However, this means that the rate of increase obtained at the beginning of measurement (cumulative rotation speed = less than 100 times) is used as data. It does not mean that it is not effective, but it can be a valid evaluation target as the initial increase rate.

Next, for each sample, the coefficient of friction at the time when the cumulative number of revolutions was 20000, the coefficient of friction at the time when the cumulative number of revolutions was 600,000, Table 2 shows the rate of increase in the area.

Table 2

As described above, the “increase rate” is defined by the coefficient of friction of the surface of the hard coat layer 15 that increases for 100 slides. For example, in sample # 1, (1.1 1 (Coefficient of friction at the time when the cumulative number of revolutions is 6 000) — 0.94 (Coefficient of friction at the time of the cumulative number of revolutions of 2 000)) / (600 000-200 0) XI 0 0 Given by As shown in Table 2, in the stable region, the increase rate of the coefficient of friction was as small as 0.0007 or less in all samples. In particular, for samples # 3, # 4, # 5, # 8, # 9, # 10, # 13, # 14, and # 15 having a lubricant content of 1.0% by weight or more, The rate of increase in the coefficient of friction was as small as 0.02 or less. Next, for each sample, the friction coefficient in the initial state (cumulative rotation speed = 100 ° or less) and the friction coefficient at the time when the cumulative rotation speed is 100 Table 3 shows the numbers and the rate of increase of the friction coefficient between them (initial rate of increase).

Table 3

As shown in Table 3, in each of the samples, a very small value was obtained in which the initial addition rate of the friction coefficient was 0.03 or less. In particular, for Sample # 4 having a lubricant content of 3.0% by weight and Samples # 5 and # 15 having a lubricant content of 5.0% by weight, the initial increase rate of the coefficient of friction was small. A very small value of 0.01 or less was obtained.

[Example 2]

Next, prepare the same nine samples as samples # 1, # 3, # 5, # 6, # 8, # 10, # 11, # 13, and # 15 above, and set them at a temperature of 8 It was stored for 200 hours in an environment at 0 degrees and a relative humidity of 5% or less. After that, the friction coefficient of the surface of each sample was measured in the same manner as in Example 1 above.

FIG. 6 is a graph showing the measurement results of the friction coefficients of # 1, # 3, # 5, # 6, # 8, # 10, # 11, # 13, and # 15. In FIG. 6, the vertical axis indicates the coefficient of friction, and the horizontal axis indicates the cumulative rotation speed of the optical recording medium. Referring to FIG. 6, even after storage for 200 hours in an environment at a temperature of 80 ° C. and a relative humidity of 5% or less, each sample exhibited the characteristics obtained in Example 1. 09736

It can be seen that almost the same characteristics as those shown in FIG.

For each sample, after storage in the above environment, the friction coefficient at the time when the cumulative rotation speed was 2000 times, the friction coefficient at the time when the cumulative rotation speed was 600 times, and the friction between them Table 4 shows the coefficient increase rate (increase rate in the stable region).

Table 4

Furthermore, for each sample, after storage in the above environment, the friction coefficient in the initial state (cumulative rotation speed = 100 times or less), the friction coefficient when the cumulative rotation speed is 100 times, Table 5 shows the increase rate (initial increase rate) of the friction coefficient between the two.

Table 5

As shown in Tables 4 and 5, in each of the samples, deterioration in the rate of increase in the coefficient of friction due to storage in the above environment did not substantially appear.

As described above, in the present invention, since the friction coefficient of the surface on the light incident surface side of the optical recording medium is reduced, the surface on the light incident surface side is damaged. It is hard to be clear. Therefore, according to the present invention, it is possible to provide a highly reliable optical recording medium.

Further, in the present invention, since the rate of increase in the friction coefficient of the surface on the light incident surface side of the optical recording medium is suppressed, dust or dirt adhered to the surface of the optical recording medium by the user can be removed from a nonwoven fabric or tissue paper. A sufficiently low coefficient of friction is maintained even when frequently wiped with paper or the like or with a rag containing water or detergent aqueous solution. Therefore, according to the present invention, it is possible to provide a highly reliable optical recording medium in which the light incident surface of the optical recording medium is not easily damaged for a long period of time.

Claims

The scope of the claims

1. An optical recording medium comprising at least a light-transmitting substrate, wherein data is recorded, recorded, or reproduced by irradiating a laser beam through the light-transmitting substrate. While rotating at a rotation speed of 0 to 300 rpm, a plane of 5 to 50 g Zcm ₂ is formed on the surface of the light-transmitting substrate via a self-adhesive long-fiber nonwoven fabric containing cellulose as a main component. An optical recording medium characterized in that the coefficient of friction measured by applying a typical load is 1.5 or less.

2. The optical recording medium according to claim 1, wherein the friction coefficient is a value when the rotation speed of the optical recording medium is set to 100 to 1500 rpm.

3. The optical recording medium according to claim 1, wherein the coefficient of friction of the surface of the translucent substrate is 1.0 or less.

4. The optical recording medium according to claim 3, wherein the coefficient of friction of the surface of the translucent substrate is 0.8 or less.

5. The optical recording medium according to claim 1, wherein the light-transmitting substrate comprises a light-transmitting layer and a hard coat layer provided on a surface thereof.

6. The optical recording medium according to claim 5, wherein said light transmitting layer has a thickness of 5 to 300 μm.

7. The optical recording medium according to claim 5, wherein the hard coat layer contains a lubricant.

8. The optical recording medium according to claim 7, wherein the lubricant is a silicone-based lubricant, a fluorine-based lubricant, or a fatty acid ester-based lubricant.

9. The content of the lubricant is 0.1 to 5.0 mass. 8. The optical recording medium according to claim 7, wherein the ratio is / ₀ .

10. The optical recording medium according to claim 1, wherein the coefficient of friction is a value in a region where the cumulative rotation number of the optical recording medium is 100 or less.

1. The optical recording medium _{t according} to claim 1, wherein the friction coefficient is a value at the time when the cumulative rotation number of the optical recording medium is _100,000.

12. The optical recording medium according to claim 1, wherein the coefficient of friction is a value at the time when the cumulative rotation number of the optical recording medium is 100,000 times.

1 3. The coefficient of friction is 80 ° C, 5 ° /. 2. The optical recording medium according to claim 1, wherein the value is a value after storage for 100 to 100 hours in an environment of the following relative humidity.

1 4. An optical recording medium comprising at least a light-transmitting substrate, wherein data is recorded and / or reproduced by irradiating a laser beam through the light-transmitting substrate, An optical recording medium characterized in that the rate of increase in the coefficient of friction for 100 times of sliding on the surface is 0.03 or less.

15. The method according to claim 14, wherein the rate of increase is not more than 0.01. An optical recording medium according to claim 1.

16. The optical recording medium according to claim 15, wherein the increase rate is 0.007 or less.

17. The optical recording medium according to claim 16, wherein the increase rate is not more than 0.002.

18. The optical recording medium according to claim 14, wherein the rate of increase is a value in a region where the number of times of sliding is less than 1,000 times.

19. The optical recording medium according to claim 16, wherein the increase rate is a value in an area where the number of times of sliding is 100,000 or more.

20. The optical recording medium according to claim 14, wherein the light-transmitting substrate comprises a light-transmitting layer and a hard coat layer provided on the surface thereof.

21. The optical recording medium according to claim 20, wherein the thickness of the light transmitting layer is 5 to 300π.

22. The optical recording medium according to claim 20, wherein the hard coat layer contains a lubricant.

23. The optical recording medium according to claim 22, wherein the lubricant is a silicone-based lubricant, a fluorine-based lubricant, or a fatty acid ester-based lubricant.

24. The optical recording medium according to claim 22, wherein the content of the lubricant is 0.1 to 5.0% by mass.

25. The method according to claim 24, wherein the coefficient of friction is a value after storage for 100 to 100 hours in an environment at a temperature of 80 degrees and a relative humidity of 5% or less. An optical recording medium according to claim 1.

2 6. The rate of increase is a value measured by bringing a measuring member into planar contact with the surface of the light-transmitting substrate and detecting a tensile force generated on the measuring member. 15. The optical recording medium according to claim 14, wherein: