JP2006120318A - Optical information medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information medium which is excellent in a wiping off property of organic stains, such as fingerprints adhered to a laser beam incident side surface of an optical information medium, and can maintain excellent recording/reproducing characteristics over a long term. <P>SOLUTION: The optical information medium has an information recording layer on a support substrate and a translucent substrate on the information recording layer and it is used in such that a recording/reproducing beam to be incident on information recording layer through a translucent substrate. The translucent substrate includes an internal layer at the information recording layer side and a surface layer on the internal layer and the surface layer includes cured materials of radiation curing type resin materials. In the cured materials, inorganic fine particles are distributed, and a fluorine atom without fluidity or silicone without fluidity exist on at least a part of the surface of the translucent substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical information medium such as a read-only optical disk and an optical recording disk.

  In recent years, in optical information media, it has been required to further increase the recording density in order to store vast amounts of information such as moving image information, and research and development have been conducted extensively to further increase the recording capacity. . One of them is proposed to shorten the recording / reproducing wavelength, increase the numerical aperture (NA) of the objective lens, and reduce the condensing spot diameter of the recording / reproducing beam, as seen on DVDs, for example. Has been. Actually, when compared with a CD, the recording / reproducing wavelength λ is changed from 780 nm to 650 nm and the numerical aperture (NA) is changed from 0.45 to 0.60, thereby increasing the recording capacity (4.7 GB / surface). ) Has been achieved. Recently, as a method for recording high-quality moving images for a long time, the recording / reproducing wavelength is further shortened to about 400 nm and the numerical aperture is increased to 0.85, so that the recording capacity is more than four times that of DVD. Attempts have been made to achieve.

  However, when the recording density is increased in this way, the diameter of the condensing spot of the recording / reproducing beam is reduced, so that it is more sensitive than conventional to dust and fingerprints adhering to the laser beam incident side surface of the medium. turn into. In particular, for dirt containing organic matter such as fingerprints, many measures have been considered so far because the influence of dirt on the laser beam incident side surface is large and it is difficult to remove it. .

  Specifically, for example, in JP-A-10-110118 and JP-A-11-293159, when a hard coat agent coating is formed on the surface of an optical disk substrate made of polycarbonate or the like, non-hard coating agent is not included in the hard coat agent. It has been proposed to knead a crosslinkable fluorosurfactant. According to the above publication, a non-crosslinked fluorosurfactant is added to a hard coat agent made of an ultraviolet curable resin, and this is applied to the surface of a translucent substrate and cured, whereby a fingerprint is obtained. It is said that an optical information medium which is difficult to adhere and which can be easily removed even if attached is obtained. In other words, it is concluded that the wiping property of organic stains, particularly when fingerprints are attached, can be improved by reducing the surface free energy on the laser beam incident side surface and enhancing the water and oil repellency.

  However, none of the above publications has quantitatively confirmed whether the fingerprint removability has actually improved. By measuring the contact angles of several types of liquids with respect to the treated surface, it is only inferred that the organic soil removal properties are improved by improving the contact angles of the liquids.

  By the way, as a method for verifying the effect of improving the antifouling property by the surface treatment in the optical discs subjected to various water repellency / oil repellency surface treatments listed above, a fingerprint is actually attached and wiped off. In many cases, a method for visually confirming the property is used. Alternatively, the contact angle of various liquids such as water and aliphatic hydrocarbons with respect to the treated surface is often measured on the assumption that contaminants are easy to remove if water and oil repellency is high. Is called. However, the latter evaluation based on contact angle or surface free energy is an indirect evaluation method. Therefore, the above-mentioned assumption that the antifouling property is excellent when the water / oil repellency is high is valid, and can be used as the antifouling property evaluation method only when it is extremely limited. Moreover, this evaluation method gives only a relative evaluation result to the last. That is, when applied to the surface of an optical disk, it is practically impossible to determine a threshold value for whether or not it can be used practically with respect to the surface free energy or the contact angle. On the other hand, the former method of actually attaching a fingerprint by a human hand is of course poor in quantification and reproducibility and is not suitable as an evaluation method.

  In JP-A-10-110118 and JP-A-11-293159, an artificial fingerprint solution is obtained by dissolving a small amount of sodium chloride, urea, and lactic acid in a mixed solution of water and ethanol, and this is used as the surface of the optical disk. The antifouling property is also evaluated by visually determining the wiping property after adhering to the surface. This artificial fingerprint liquid is described in JIS K2246: 1994 “rust prevention oil”. The JIS standard specifies a performance test method for rust prevention oil used for temporary rust prevention of metal materials such as steel. Therefore, the artificial fingerprint liquid also determines the corrosiveness to metal materials. It is prepared for. For this reason, there is no general versatility for other purposes. In fact, even when the artificial fingerprint liquid mainly composed of water and ethanol is attached to the surface of an optical disk substrate made of a resin such as polycarbonate, in most cases, the artificial fingerprint liquid is repelled and does not fix on the substrate surface. . Therefore, even if it is a resin substrate surface that has not been surface-treated or an optical disc surface that has been subjected to the above water- and oil-repellent surface treatments, it exhibits the same wiping property as to the artificial fingerprint liquid. It is considered a thing. In other words, it is almost meaningless to use the artificial fingerprint liquid defined in JIS K2246: 1994 for the evaluation of the antifouling property or the fingerprint removability of the optical disk surface.

JP-A-10-110118 JP-A-11-293159

  The present invention has been devised in view of such a situation, and its purpose is to have good wiping off of organic stains such as fingerprints adhering to the laser beam incident side surface of an optical information medium, and good recording over a long period of time. / To provide an optical information medium capable of maintaining reproduction characteristics.

The object is achieved by the present inventions (1) to (5) below.
(1) An optical information medium having an information recording layer on a support substrate and a translucent substrate on the information recording layer, and used so that a recording / reproducing beam enters the information recording layer through the translucent substrate Because
The translucent substrate includes an inner layer on the information recording layer side and a surface layer on the inner layer,
The surface layer includes a cured product of a radiation curable resin material, and inorganic fine particles are dispersed in the cured product.
At least a part of the surface of the translucent substrate contains fluorine atoms having no fluidity or silicone having no fluidity,
On the surface of the translucent substrate of the optical information medium, 0.4 parts by weight of Kanto loam of the 11th kind of test powder 1 specified in JIS Z8901 as a particulate material with respect to 1 part by weight of triolein as a dispersion medium. The following predetermined operations with pseudo fingerprint liquid containing:
(a) First, a silicone rubber stopper with a diameter of 16 mm on the end face is covered with dry waste, and a portion covering the vicinity of the end face of the silicone rubber stopper on the waste is impregnated with 2.0 mL of pseudo fingerprint liquid,
(b) Next, the end face of the silicone rubber stopper is pressed vertically against the surface of the light-transmitting substrate of the optical information medium with a load of 4.9 N / cm ² with a cloth impregnated with the pseudo-fingerprint liquid interposed therebetween. Slide 50 times in the radial direction,
After adhering by the following predetermined operations:
(c) First, prepare the same silicone rubber stopper as used in (a) above and the same waste as used in (a) above, and add ethanol 2 to the waste as in (a) above. Impregnating with 0 mL,
(d) Next, the end face of the silicone rubber stopper is vertically pressed at a load of ^2.5 N / cm ² with the waste impregnated with ethanol sandwiched between the places where the waste is slid in (b) above, and an optical information medium is obtained. 20 reciprocating slides in the radial direction of
(e) Further, replace the waste with a new one, and impregnate the waste with 2.0 mL of ethanol in the same manner as in (c) above.
(f) Again, the end face of the silicone rubber stopper was pressed vertically with a load of ^2.5 N / cm ² across the waste impregnated with ethanol at the location where the waste was slid in (d) above, and the optical information medium Slide 20 times in the radial direction,
(g) The ethanol on the surface of the light-transmitting substrate of the optical information medium is completely dried, and static electricity is removed by a discharge blow.
When the wiping operation of the attached pseudo-fingerprint liquid is performed, the dynamic friction coefficient of the surface of the translucent substrate after the wiping operation is applied to the surface of the translucent substrate of the optical information medium. An optical information medium in which contact is made at 20 mN and the optical information medium is measured by rotating the optical information medium at a linear velocity of 1.4 m / s, but does not increase by 0.1 or more with respect to the coefficient of dynamic friction before the pseudo-fingerprint liquid is attached.

(2) An optical information medium having an information recording layer on a support substrate and a translucent substrate on the information recording layer, and used so that a recording / reproducing beam enters the information recording layer through the translucent substrate. Because
The translucent substrate includes an inner layer on the information recording layer side and a surface layer on the inner layer,
The surface layer includes a cured product of a radiation curable resin material, and inorganic fine particles are dispersed in the cured product.
At least a part of the surface of the translucent substrate contains fluorine atoms having no fluidity or silicone having no fluidity,
On the surface of the translucent substrate of the optical information medium, 0.4 parts by weight of Kanto loam of the 11th kind of test powder 1 specified in JIS Z8901 as a particulate material with respect to 1 part by weight of triolein as a dispersion medium. The following predetermined operations with pseudo fingerprint liquid containing:
(a) First, a silicone rubber stopper with a diameter of 16 mm on the end face is covered with dry waste, and a portion covering the vicinity of the end face of the silicone rubber stopper on the waste is impregnated with 2.0 mL of pseudo fingerprint liquid,
(b) Next, the end face of the silicone rubber stopper is pressed vertically against the surface of the light-transmitting substrate of the optical information medium with a load of 4.9 N / cm ² with a cloth impregnated with the pseudo-fingerprint liquid interposed therebetween. Slide 50 times in the radial direction,
After adhering by the following predetermined operations:
(c) First, prepare the same silicone rubber stopper as used in (a) above and the same waste as used in (a) above, and add ethanol 2 to the waste as in (a) above. Impregnating with 0 mL,
(d) Next, the end face of the silicone rubber stopper is vertically pressed at a load of ^2.5 N / cm ² with the waste impregnated with ethanol sandwiched between the places where the waste is slid in (b) above, and an optical information medium is obtained. 20 reciprocating slides in the radial direction of
(e) Further, replace the waste with a new one, and impregnate the waste with 2.0 mL of ethanol in the same manner as in (c) above.
(f) Again, the end face of the silicone rubber stopper was pressed vertically with a load of ^2.5 N / cm ² across the waste impregnated with ethanol at the location where the waste was slid in (d) above, and the optical information medium Slide 20 times in the radial direction,
(g) The ethanol on the surface of the light-transmitting substrate of the optical information medium is completely dried, and static electricity is removed by a discharge blow.
The contact angle of water (temperature 20 ° C., relative humidity 60% environment) after the wiping operation with the surface of the translucent substrate after the wiping operation of the attached pseudo fingerprint liquid is the contact before the pseudo fingerprint liquid is attached. An optical information medium that does not decrease by more than 15% with respect to the corner.

  (3) Before attaching the pseudo-fingerprint liquid, the dynamic friction coefficient of the surface of the light-transmitting substrate (a nylon tip having a curvature radius of 5 mm at the tip is brought into contact with the surface of the light-transmitting substrate of the optical information medium with a load of 20 mN. (1) or (2) according to the above (1) or (2), which is 0.4 or less.

  (4) Of the above (1) to (3), the contact angle of water (temperature 20 ° C., relative humidity 60% environment) with respect to the surface of the transparent substrate is 75 ° or more before the pseudo-fingerprint liquid is attached. The optical information medium according to any one of the above.

  (5) The optical information medium according to any one of (1) to (4), which is used in a system in which the minimum diameter of the recording / reproducing beam on the surface of the translucent substrate is 500 μm or less.

  Since the optical information medium of the present invention has a good wiping property for organic stains such as fingerprints adhering to the surface, good recording / reproducing characteristics can be maintained over a long period of time.

  Hereinafter, embodiments of the present invention will be described in detail.

Fingerprint resistance test method for optical information media Optical information media, especially oil components such as fingerprints of optical information media, such as cartridges, shells, and caddies, that do not have a mechanism to protect the media surface from contact with fingers In order to evaluate the adherence and / or removability, a pseudo fingerprint pattern is quantitatively adhered to the surface of the optical information medium, and the wiping property is evaluated under predetermined conditions. For this purpose, it is required to prepare a pseudo-fingerprint component having properties as close as possible to an actual fingerprint and to quantitatively attach it to the surface of the light-transmitting substrate of the optical information medium by a predetermined method. Moreover, it is preferable that the material constituting the pseudo fingerprint component can be easily obtained and can be easily prepared. Specifically, it is preferable to use a pseudo fingerprint component prepared according to the following guidelines.

  At this time, the use of a uniform component system composed only of liquid does not approximate the actual fingerprint removability. For example, when triolein, one of the sebum constituents, is used as a uniform system, the surface tension of triolein at 25 ° C. is 34 mN / m, so that polytetrafluoroethylene having a critical surface tension of about 18 mN / m is used. If it is (PTFE) surface, it does not get wet with triolein and plays completely. However, an actual fingerprint cannot be fixed even on the surface of PTFE. This is mainly due to the fact that the fingerprint is not composed only of a liquid substance, but is composed of a heterogeneous system including insoluble substances and viscous substances. Therefore, if a non-homogeneous system in which a suitable insoluble component is added to a liquid component contained in an actual fingerprint and / or a dispersion medium composed of a liquid similar thereto, a pseudo fingerprint component that satisfies the object of the present invention is formed. Can be obtained.

Here, the critical surface tension will be described. Water repellency and oil repellency can be uniquely expressed by the critical surface tension (γ _C / mNm ⁻¹ ), which is a measure of the surface free energy of the substance. The critical surface tension can be obtained from the actual measured contact angle. Specifically, the contact angle (θ / rad) on a smooth surface made of a specific substance is measured for several saturated hydrocarbon liquids having a known surface tension (surface tension: γ ₁ / mNm ⁻¹ ), and cos θ The value extrapolated to cos θ = 1 in the plot with γ ₁ is the critical surface tension γ _C of the specific substance. In order for a substance to repel a liquid, the critical surface tension γ _{C of the} substance needs to be lower than the surface tension γ ₁ of the liquid. For example, a material having a surface composition of methylene chains (—CH ₂ —CH ₂ —) has a γ _C of 31 mNm ⁻¹ , and therefore the material has a surface tension γ _{1 at} a temperature of 20 ° C. of 73 mNm ⁻¹ . Some water repels, but completely wets n-hexadecane with a surface tension γ ₁ of 28 mNm ⁻¹ and the contact angle becomes 0 degrees.

  Most of the solid components contained in fingerprints are proteins called keratins. Therefore, most simply, a pseudo-fingerprint component meeting the purpose of the present invention can be prepared by adding and mixing keratin fine powder to a suitable dispersion medium. Actually, a mixture of keratin fine powder in an appropriate ratio in a dispersion medium such as water, oleic acid, squalene, triolein or the like can be effectively used as the pseudo fingerprint component of the present invention. However, generally available keratin is extremely expensive and not readily available in large quantities. Furthermore, since commercially available keratin has a different particle size distribution from keratin contained in an actual fingerprint, it is necessary to prepare the particle size distribution in advance if necessary. Therefore, a method using commercially available keratin is not necessarily a preferable method in terms of simplicity or measurement accuracy and reproducibility.

  In order to solve such problems, as a result of the inventors searching for a particulate substance that can be used in place of keratin, liquids constituting human sweat and sebum and / or liquids having properties close to that, For example, fine particles having good wettability with respect to higher fatty acids, ester derivatives thereof, or aqueous solutions thereof and having particle sizes close to keratin contained in the actual fingerprint component can be used as pseudo-fingerprint components. It has been found that it is suitable as a particulate matter to be added.

As the particulate material used for the pseudo fingerprint component, for example, a particulate material containing an inorganic component and having an average particle diameter (or median diameter) of 100 μm or less, more preferably 50 μm or less is preferable. Examples of particulate substances containing an inorganic component and having an average particle size of 100 μm or less include JIS Z8901 Test Powders 1 and 2, ISO Test Powder 12103-1, or Japan Powder Industry Technology Association (APPIE) Standard Examples include powder. Any of the above test powders is suitable for achieving the object of the present invention because it has a uniform particle size and is available at a relatively low cost. Further, not only the above test powders themselves, but also from at least one kind of inorganic particles contained in each of the test powders, for example, various oxide particles such as SiO ₂ , Fe ₂ O ₃ , Al ₂ O _3, etc. You may select and use at least 1 sort. The average particle diameter (or median diameter) of the particulate material is preferably 0.05 μm or more, more preferably 0.5 μm or more. If the particulate matter is too large or too small, it will be difficult to exhibit a sufficient function as a substitute for keratin contained in an actual fingerprint.

  The particulate matter containing an inorganic component shows the same effect as the keratin particle as a constituent component of the pseudo fingerprint, and is less expensive than the keratin particle. Therefore, it is preferable that the particulate matter containing an inorganic component accounts for 100% by mass of the particulate matter contained in the pseudo fingerprint component. However, if necessary, a particulate material containing an organic component such as keratin particles may be used in combination. However, in order to reduce costs and stabilize performance, the particulate matter containing an inorganic component preferably occupies 50% by mass or more, more preferably 80% by mass or more of the total particulate matter.

  On the other hand, as the dispersion medium for dispersing the particulate matter, any liquid can be used without particular limitation as long as it is a liquid constituting human sweat or sebum and / or a liquid having properties close thereto. Specifically, a liquid selected from higher fatty acids (such as oleic acid) and ester derivatives thereof (such as diglycerides and triglycerides (such as triolein)) and terpenes (such as squalene), or an aqueous solution containing at least one of these. Or the liquid mixture containing these at least 2 sorts is preferable. Moreover, if it is a liquid which has the property similar to these liquids, it can be used without being limited to the above. For example, ethanol or liquid paraffin may be appropriately added to the above liquid.

  It is more preferable to add a wax, that is, an ester of a higher fatty acid and a monohydric alcohol, to the liquid component at room temperature to increase the viscosity. As waxes, for example, natural waxes such as candelilla wax, carnauba wax, aucuric wax, rice wax, sugar wax, wood wax, beeswax, whale wax, china insect wax, shellac wax, montan wax, etc., cholesteryl stearate Synthetic waxes such as myristyl myristate and cetyl palmitate can be used. The addition ratio of the above various waxes may be appropriately determined according to the characteristics of the recording / reproducing optical system of the optical information medium to be evaluated, the purpose of the evaluation, and the like.

  In the present specification, the liquid having properties close to the liquid constituting human sweat and sebum means a liquid whose surface tension, boiling point and viscosity are close to the liquid constituting human sweat and sebum. Specifically, the surface tension at 20 to 30 ° C. is preferably 20 to 50 mN / m, more preferably 20 to 40 mN / m, and the boiling point is preferably 80 ° C. or more, more preferably 100 ° C. or more, and still more preferably. It is desirable that the viscosity at 150 ° C. or higher, most preferably 200 ° C. or higher, and the viscosity at 20 to 30 ° C. is preferably 500 cP or less, more preferably 0.5 to 300 cP, and further preferably 5 to 250 cP.

  Further, the particulate material used for the pseudo fingerprint component preferably has a critical surface tension at 20 to 30 ° C. larger than the surface tension at 20 to 30 ° C. of the dispersion medium used for the pseudo fingerprint component, and the critical surface. The tension is preferably 40 mN / m or more, more preferably 50 mN / m or more. Each of the particulate materials exemplified as the particulate material containing an inorganic component has such desirable properties with respect to the critical surface tension.

  An appropriate mixing ratio between the particulate matter and the dispersion medium depends largely on a method for attaching a pseudo fingerprint component to the medium surface, which will be described later, and thus cannot be defined unconditionally. However, generally, it is preferable to add 0.1 to 5.0, more preferably 0.1 to 3.0, of the particulate matter to the dispersion medium 1 in terms of mass ratio. If the mixing ratio of the particulate matter to the dispersion medium is too low or too high, it becomes difficult to function effectively as a pseudo fingerprint component. However, the dispersion medium here is different from the diluent added to improve the transferability of the pseudo fingerprint component. For example, when a diluent such as isopropyl alcohol or methyl ethyl ketone is added to a mixture of a dispersion medium such as triolein or squalene and a particulate substance to improve pseudo-fingerprint transfer, these diluents are not In the book, it is not called a dispersion medium. That is, after transferring to the test piece, only the component remaining as the pseudo fingerprint component is called a dispersion medium, and is distinguished from the diluent that is finally distilled off.

  When adhering the pseudo fingerprint component to the medium surface, it is preferable to use a pseudo fingerprint transfer material made of an elastomer. Specifically, it is preferable to prepare a pseudo fingerprint transfer material made of silicone rubber, butadiene rubber, urethane rubber or the like and use it. The pseudo-fingerprint transfer material may actually be shaped from a person's finger and may have a shape imitating a fingerprint pattern, but more simply, rubber for artificial fingerprint liquid printing specified in JIS K2246-1994 It is preferable to use a stopper. That is, the smaller round surface (diameter: about 26 mm) of No. 10 rubber plug is roughened by rubbing with an AA240 abrasive specified in JIS R6251 or JIS R6252 or an abrasive having equivalent performance. It can be used as a pseudo fingerprint transfer material. However, as long as the fingerprint transfer property substantially equivalent to the above can be obtained, the material is not particularly limited and can be preferably used. In order to make the dimensions close to the actual fingerprint, it is preferable to use a rubber plug having a diameter smaller than that of the above-described rubber plug, specifically, a rubber plug having a diameter of 8 to 25 mm, and a rubber plug having a diameter of 8 to 20 mm is used. It is more preferable.

  A method of transferring the pseudo fingerprint component as a pseudo fingerprint onto the optical disk surface using such a pseudo fingerprint transfer material can be appropriately determined according to the purpose of evaluation. For example, an original plate for pseudo fingerprint pattern transfer can be prepared in advance, and the pseudo fingerprint can be transferred from the original plate to the optical information medium surface to be evaluated using the rubber plug. Specifically, the pseudo fingerprint component is uniformly applied onto a rigid substrate made of glass or resin. As a coating method at this time, an appropriate method may be used from various coating methods such as a spin coating method and a dip coating method. When the pseudo fingerprint component is applied on the substrate, it may be diluted with an appropriate organic solvent such as isopropyl alcohol or methyl ethyl ketone in order to obtain good application properties. These diluents may be distilled off by air drying or heat drying after application. In this specification, the substrate thus manufactured and onto which the pseudo fingerprint component is uniformly applied is referred to as a master plate for pseudo fingerprint transfer.

  The pseudo-fingerprint transfer material is pressed against the surface of the original plate on which the pseudo-fingerprint component is applied with a constant load, and the pseudo-fingerprint component is transferred to the transfer material. Thereafter, the transfer material having the pseudo fingerprint component transferred is pressed against the surface of the optical information medium to be tested with a constant load, and the pseudo fingerprint pattern is transferred to the medium surface.

  By using the method described above, an artificial fingerprint can be attached quantitatively to the laser beam incident side surface of the medium in a form that mimics actual fingerprint attachment very well. Therefore, it is possible to quantify the difficulty of attaching fingerprints, the ease of wiping off, and the like with good reproducibility.

On the other hand improved optical information medium of the fingerprint removing property, described above, in order to realize a fingerprint removing property is good optical information medium when using the fingerprint removing property test method according to pseudo fingerprint components, the present inventors have variously Upon examination, it has become clear that an optical information medium having the characteristics described in detail below is desirable.

  A configuration example of the optical information medium of the present invention is shown in FIG. This optical information medium is a recording medium, and has a recording layer 4 as an information recording layer on a support base 20 having a relatively high rigidity, and is relatively thin on this recording layer 4, preferably 30 to 30 mm in thickness. It has a translucent substrate 2 of 300 μm.

The effect on the recording / playback characteristics due to fingerprint attachment depends on the diameter of the laser beam on the laser beam incident surface of the medium (minimum diameter if the beam cross section is elliptical). If this diameter is small, error correction is impossible. The effect becomes large, such as a continuous error. According to the study by the present inventors, when the diameter of the laser beam on the surface on the incident side of the medium is 500 μm or less, particularly 300 μm or less, there is an adverse effect on recording / reproducing characteristics when a fingerprint is attached during handling of the medium. Was found to be prominent. Note that the diameter of the laser beam on the laser beam incident side surface of the medium is such that the thickness of the translucent substrate in FIG. 1 is t, the refractive index of the translucent substrate at the wavelength of the laser beam is n, and the recording / reproducing optics. When the numerical aperture of the objective lens of the system is NA,
2t tan [sin ^-1 (NA / n)]
It is represented by

  The present invention can be applied regardless of the type of the recording layer. That is, for example, it can be applied to a phase change recording medium, a pit formation type recording medium, and a magneto-optical recording medium. Normally, a dielectric layer and a reflective layer are provided on at least one side of the recording layer for the purpose of protecting the recording layer and for optical effects, but they are not shown in FIG. Further, the present invention is not limited to the recordable type as shown in the figure, but can be applied to a reproduction-only type. In that case, a pit row is formed integrally with the support base 20, and a reflective layer (metal layer or dielectric multilayer film) covering the pit row constitutes an information recording layer.

  The present invention can also be applied to an optical information medium having the structure shown in FIG. The medium shown in FIG. 2 has a recording layer 4 and a protective layer 6 in this order on a translucent substrate 2. In this structure, the light-transmitting substrate 2 having a relatively high rigidity is used. Note that two media each having the structure shown in FIG. 1 or FIG. 2 can be bonded to each other so that the translucent substrate 2 is on the outer side to form a double-sided recording type medium.

  In both FIG. 1 and FIG. 2, the surface of the translucent substrate 2 constitutes the laser beam incident side surface of the medium, and the laser beam for recording or reproduction enters the recording layer 4 through the translucent substrate 2. To do.

  In order to achieve the desired performance, the translucent substrate 2 may be formed of two or more different layers. In FIG. 1 and FIG. 2, as an example, a translucent substrate 2 is illustrated as having a two-layer structure of an inner layer 2 i and a surface layer 2 s.

  In the medium of the present invention, the contact angle of water with the laser beam incident side surface of the translucent substrate 2 is preferably 75 ° or more and 90 ° or more in a temperature 20 ° C. and relative humidity 60% environment. Is more preferable. The upper limit of the contact angle is not particularly limited, but is generally about 150 °. Further, even if the contact angle is increased to 100 ° or more, the wiping property of the fingerprint is not significantly improved.

  By the way, as means for achieving a contact angle of 90 ° or more, and further around 100 °, for example, as shown in the above-mentioned JP-A-10-110118 and JP-A-11-293159, a hard coat is used. A non-crosslinked fluorosurfactant is kneaded into the agent, or a fluoropolymer such as perfluoropolyether as disclosed in Japanese Patent Application Laid-Open No. 2000-082236 is applied to the surface of the translucent substrate. The technique to do is mentioned. Moreover, it is not limited to a fluorine-type compound, For example, the method of using a silicone type polymer etc. is also known.

  However, in the case of a method of kneading a fluorine-based or silicone-based surfactant having excellent water and oil repellency in the hard coat, water and oil repellency is expressed by the surfactant that exudes to the hard coat surface. Since the penetrating surfactant is removed from the hard coat surface when the fingerprint is wiped off, the water repellency of the hard coat surface is greatly deteriorated by wiping off the fingerprint. In addition, since the exuded surfactant is not fixed on the hard coat surface, it has fluidity, and thus the fingerprint component adhering to the hard coat surface and the surfactant are mixed. The fingerprint wiping operation further promotes mixing of the surfactant and the fingerprint component. Therefore, it is difficult to remove the fingerprint by wiping. Similar problems also occur in a method in which a fluorine-based polymer or a silicone-based polymer is applied to the surface of a translucent substrate.

  In JP-A-11-293159, as a surfactant to be contained in a hard coat, a non-crosslinked fluorosurfactant that is easily wiped off, and a crosslinkable fluorochemical interface having good wiping durability. Combined with active agent. However, as described in paragraphs 0021 to 0023 of the same publication, the invention described in the publication discloses antifouling properties after the non-crosslinked fluorosurfactant is wiped off. Is to supplement. That is, the invention described in the publication does not solve the fact that the mixing of the surfactant and the fingerprint component is facilitated by the fingerprint wiping operation.

  Such fatal problems have not been pointed out in the past, as described above, which is a good imitation of actual fingerprint attachment and a quantitative fingerprint removability test. This is because there was no method.

  Therefore, in the optical information medium of the present invention, special care must be taken so that mixing of the fluid component present on the surface of the translucent substrate and the attached fingerprint component does not occur. Whether or not a fluid component miscible with the fingerprint component is present on the surface of the translucent substrate can be easily confirmed by the following method.

When the fluid component contains a compound having lubricity, the presence of the fluid component is confirmed by wiping the surface of the translucent substrate with a waste cloth and examining the change in the dynamic friction coefficient before and after the wiping operation. can do. Specifically, a pseudo fingerprint component is impregnated in Wes (for example, Bencot Lint Free CT-8 manufactured by Asahi Kasei Kogyo Co., Ltd.), and the surface of the translucent substrate is 6 to 400 at a load of 1.0 to 10 N / cm ^2. Rub once, preferably 10-200 times. Thereafter, using a volatile organic solvent such as methanol, ethanol, methyl ethyl ketone, and acetone, an operation for removing the pseudo fingerprint component remaining on the surface of the translucent substrate is performed, and then the dynamic friction coefficient of the surface is measured. . Instead of removing the pseudo fingerprint component with a volatile organic solvent, the pseudo fingerprint component may be distilled off by heating the optical information medium.

  If the dynamic friction coefficient after wiping off the pseudo-fingerprint component with waste is increased by 0.1 or more compared to the initial dynamic friction coefficient (before wiping), a non-negligible amount of fluidity is applied to the surface of the translucent substrate. It may be considered that the component is present. On the contrary, if the increase amount of the dynamic friction coefficient is less than 0.1, even if a very small amount of fluid component is present, there is almost no adverse effect on the fingerprint removability. The dynamic friction coefficient is measured by bringing a tip made of nylon having a radius of curvature of 5 mm into contact with the translucent substrate surface of the optical information medium at a load of 20 mN and rotating the optical information medium at a linear velocity of 1.4 m / s.

  Further, when the fluid component contains a compound having water repellency, the fluid component is examined by examining the change in the contact angle of water (temperature 20 ° C., relative humidity 60% environment) before and after the wiping operation. Can be confirmed. In this case, if the contact angle after the wiping operation is reduced by 15% or more with respect to the initial contact angle (before wiping), it is considered that a non-negligible amount of fluid component exists on the surface of the translucent substrate. Good. On the other hand, if the contact angle decrease amount is less than 15%, even if a trace amount of fluid component is present, the fingerprint removability is hardly adversely affected.

In order to make the increase in the dynamic friction coefficient less than 0.1 in the measurement of the dynamic friction coefficient change, or to make the contact angle decrease in the measurement of the contact angle change less than 15%, the amount of the fluid component, that is, , The amount of the compound not fixed to the surface of the translucent substrate by chemical bonding or the like (abundance per unit area of the translucent substrate) is preferably 20 mg / m ² or less, more preferably 10 mg / m ² or less, More preferably it is 5 mg / m ² or less. In addition, the thickness of the layer made of the fluid component on the surface of the translucent substrate is preferably 10 nm or less, more preferably 5 nm or less, and further preferably 2 nm or less.

  Further, in the optical information medium of the present invention, the abrasion resistance and scratch resistance of the surface should be increased so that the surface of the translucent substrate will not be scratched even if the wiping operation when the fingerprint is attached is repeated. Is desirable. Specifically, the pencil hardness measured by a method based on JIS K5600-5-4: 1999 (ISO / DIS 15184: 1996) is preferably B or more, and more preferably HB or more.

  In addition, in the wear test method using wear wheels based on ISO 9352: 1995, ΔHaze (cloudiness /%) measured under the following conditions is preferably 15% or less, more preferably 7% or less. preferable. That is, CS-10F is used as a wear wheel, and the haze value after 100-turn wear with a load of 4.9 N is measured with a haze meter. At this time, as a test sample, a translucent substrate having no information recording layer such as a reflective film or a phase change film is used. In the case of the light-transmitting substrate 2 having a low rigidity made of a resin layer or a resin sheet as shown in FIG. 1, the light-transmitting substrate 2 is directly formed on the support substrate 20 without forming the information recording layer. A sample is used as a test sample. When the support base 20 is not transparent in an actual medium, a support base made of a transparent resin such as polycarbonate, methyl methacrylate, amorphous polyolefin or the like is used instead of the actual support base 20.

  As described above, the contact angle of water is 75 ° or more, and after performing the removal operation by attaching the pseudo fingerprint component, the decrease of the contact angle of water and the increase of the dynamic friction coefficient are respectively compared with the initial value. By using a translucent substrate having a pencil hardness of B or more and a haze value of 15% or less after the abrasion test, which is less than 15% and less than 0.1, the attached fingerprint is removed. An optical information medium having excellent properties can be realized.

  However, even with such an optical information medium having excellent fingerprint removability, there are cases where wiping is not easily felt when a user actually performs a wiping operation of dirt. In some cases, even an optical information medium that does not actually have excellent fingerprint removability can be easily wiped off. It has been found that the difference between the actual fingerprint removability and the user's ease of wiping depends mostly on the dynamic friction coefficient of the surface of the translucent substrate. That is, if the coefficient of dynamic friction on the surface of the translucent substrate is low, wiping can be easily felt even if the actual fingerprint removability is poor. On the other hand, even if it has excellent fingerprint removability, if the dynamic friction coefficient of the surface is high, it seems that wiping is difficult when wiping, for example, due to the feeling of being caught by a waste cloth. It will be.

  In principle, the actual fingerprint wiping performance is more important than the sensory fingerprint wiping performance. It is desirable that there is no divergence between the removability and the actual fingerprint wiping performance measured quantitatively.

  As a result of repeated investigations by the present inventors on the correlation between the magnitude of the dynamic friction coefficient and the above-described sensory fingerprint removability, the dynamic friction coefficient of the translucent substrate surface is 0.4 or less, preferably 0.3 or less. Then, it was found that the fingerprint wiping property can be recognized as good regardless of the superiority or inferiority of other properties such as surface hardness, water repellency and oil repellency.

The dynamic friction coefficient is preferably measured according to a test method defined in ISO 8295: 1995. However, other test methods may be used as long as there is no significant difference in measured values. However, regardless of which test method is used, it is preferable to use a rectangular or circular sliding piece having a contact area with the surface of the translucent substrate of 4.0 cm ² or less. Further, the sliding piece may have substantially zero contact area with the surface of the translucent substrate, that is, point contact. When the sliding piece is point-contacted, the radius of curvature of the sliding piece is preferably in the range of 0.1 to 10 mm. The load applied to the test piece by the sliding piece is controlled so as to be a constant value within the range of 1.0 × 10 ^{−3 to} 9.8 × 10 ⁻¹ N, regardless of the contact area. In the test method stipulated in ISO 8295: 1995, two test pieces made of the same material are usually used as a set, and the test is performed by bringing these test pieces into contact with each other. If it is clear that the result can be obtained, the test piece on the side on which the sliding piece is placed may be changed to a material different from the material whose dynamic friction coefficient is to be measured. For example, a smooth glass plate or a plastic material can be used as the test piece on the side on which the sliding piece is placed. Specific examples of the plastic material include various resins such as nylon, polypropylene, polyester, polyimide, polyarylate, and polyacetal. In addition, the sliding piece and the test piece on the side on which the sliding piece is placed are not prepared separately, and the sliding piece itself may also serve as one of the test pieces.

  An optical information medium that satisfies all the requirements detailed above can be realized, for example, by the following method. That is, the inner layer 2i in the translucent substrate 2 is a layer made of a thermoplastic resin or a radiation curable resin, and the surface layer 2s provided in contact with the inner layer 2i is more excellent in wear resistance and scratch resistance than the inner layer 2i. It is made of a transparent material, and is further subjected to a treatment for imparting water repellency, oil repellency and lubricity to the surface of the surface layer 2s. In this specification, radiation is a concept including both electromagnetic waves such as ultraviolet rays and particle beams such as electron beams.

  The entire translucent substrate 2 may be made of a transparent material having excellent wear resistance and scratch resistance. However, the translucent substrate made of a resin having high hardness is likely to generate a large warp, so that it is described above. Thus, it is preferable that the inner layer 2i and the surface layer 2s be separated.

  As the inner layer 2i, for example, a substrate or sheet made of a thermoplastic resin such as polycarbonate, polymethyl methacrylate, amorphous polyolefin, or a coating film made of a radiation curable resin such as an acrylic ultraviolet curable resin is used. preferable.

  On the other hand, as the material of the surface layer 2s, for example, a radiation curable resin such as an acrylic ultraviolet curable resin or an epoxy ultraviolet curable resin can be used. However, it is necessary to select the material so that the tensile modulus or Young's modulus of the cured resin is higher than that of the resin used as the material of the inner layer 2i. In order to ensure sufficient abrasion resistance and scratch resistance on the surface of the translucent substrate, inorganic fine particles such as colloidal silica are added to the resin material in advance, and the cured film More preferably, the inorganic fine particles are dispersed. Specifically, the proportion of inorganic fine particles such as silica, alumina, titania, zirconia, titanium nitride, aluminum nitride, silicon carbide, and calcium carbide in the cured film in the radiation curable resin matrix is a mass percentage. It is added so as to be 5 to 80%, more preferably 10 to 60%, and diluted with a non-reactive organic solvent as necessary, and then applied to the surface of the inner layer 2i and cured. The average particle size of the inorganic fine particles to be added is preferably 100 nm or less, and more preferably 50 nm or less. As a radiation curable resin in which inorganic fine particles are dispersed, for example, Desolite Z7503 (manufactured by JSR Corporation) is available as a commercial product.

  The thickness of the surface layer 2s constituted by the radiation curable resin is preferably 0.2 to 10 μm, and more preferably 0.5 to 5.0 μm. If the surface layer 2s is too thin, the effect of providing the surface layer 2s is not sufficiently realized. On the other hand, if the surface layer 2s is too thick, the medium tends to warp.

  The surface layer 2s may be formed by laminating an inorganic thin film on a resin layer made of a radiation curable resin.

  On the other hand, since the total thickness of the translucent substrate 2 is determined by the recording / reproducing wavelength applied to the medium and the requirements of the recording / reproducing optical system, the total thickness of the surface layer 2s and the inner layer 2i satisfies the above requirement. What is necessary is just to determine the thickness of the inner layer 2i so that it may satisfy | fill.

  The surface layer 2s constituent material may contain a non-reactive lubricant such as a non-crosslinked type, water / oil repellent, antistatic agent, leveling agent, plasticizer, etc. It is required that the amount of addition be appropriately adjusted so that the change rate of the contact angle before and after the sliding test is within a range of less than ± 10%. The appropriate addition amount strongly depends on the additive, the type of the surface layer 2s material, the formation conditions of the surface layer 2s, etc., and thus cannot be determined in general, but in general, in the cured film The proportion of the various additives occupied is preferably 3% or less, more preferably 1% or less, expressed as a percentage by mass.

  As a method for imparting water repellency, oil repellency, and lubricity to the laser beam incident side surface of the medium, for example, after the surface layer 2 s is formed, the surface of the surface layer 2 s is provided with water repellency, oil repellency, and lubricity. The method of giving to is preferable. In order to impart water repellency, oil repellency, and lubricity to the surface of the surface layer 2s, it is preferable that fluorine atoms be present on the surface.

  Specifically, it is preferable to use a silane coupling agent represented by the following formula (1).

R ₁ —Si (X) (Y) (Z) (1)

In the above formula (1), R ₁ is a substituent having water repellency, oil repellency and lubricity, X, Y and Z are each a monovalent group, and at least one of X, Y and Z is silane It is a substituent capable of forming a chemical bond by causing a polycondensation reaction with a hydroxyl group present on the surface (surface layer 2s) on which the coupling agent layer is formed.

The substituent having a water repellency / oil repellency / lubricating group represented by R ₁ refers to a compound that exhibits water repellency / oil repellency / lubricity to the compound by introducing the substituent. Water repellency and oil repellency can be uniquely expressed by the critical surface tension (γ _C / mNm ⁻¹ ), which is a measure of the surface free energy of the substance.

The water / oil repellent / lubricating group represented by R ₁ is preferably a group having a fluorinated hydrocarbon group, and examples thereof include a fluorinated alkyl group and a fluorinated alkyl group containing a fluorinated alkyleneoxy group. These total carbon numbers are preferably 1 to 5000, and particularly preferably 1 to 1000. Further, it may be linear or branched, but is preferably linear.

  Specific examples of such a fluorinated hydrocarbon group include fluorinated polyolefin segments represented by the following formulas (2) and (3), and fluorinated polyether segments represented by the formulas (4) and (5). Can be mentioned.

CF ₃ (CF ₂ ) _x CH ₂ CH ₂ − (2)
(CF ₃ ) ₂ CF (CF ₂ ) _x CH ₂ CH ₂ − (3)
CF ₃ [OCF (CF ₃ ) CF ₂ ] _x (OCF ₂ ) _y − (4)
CF ₃ (OC ₂ F ₄ ) _x (OCF ₂ ) _y − (5)
In the formulas (2) to (5), x and y are positive integers, and these are preferably in the range of 0 to 200.

  These have excellent water repellency, oil repellency, and lubricity, but especially for carbon chains, long and straight chains with no branched structure show better water repellency, oil repellency, and lubricity. .

On the other hand, the reactive group in the silane coupling agent, that is, X, Y, Z in Si (X) (Y) (Z) in the formula (1) can form a chemical bond by polycondensation with a hydroxyl group. A substituent that can form Si—O—Si by polycondensation with a substituent, particularly a hydroxyl group of a silanol group, is preferable. Examples of such a substituent include halogen, —OH (hydroxy), —OR ₂ (alkoxy), —OC (O) CH ₃ (acetoxy), —NH ₂ (amino), —N═C═O ( (Isocyanic acid) and the like can be preferably selected. R ₂ is an alkyl group. As the halogen, for example, Cl and Br are preferable. Further, the total number of carbon atoms of the alkyl group R ₂ in —OR ₂ is 1 to 5, and may be linear or branched. Moreover, although you may have a substituent which does not inhibit a chemisorption reaction, for example, a halogen is not preferable for this reason. Specific examples of —OR ₂ include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, t-butoxy and the like.

  X, Y, and Z may be the same or different from each other. If different, for example, the halogens may be different from each other or alkoxy may be different, or halogen, hydroxy, alkoxy, acetoxy, amino, and isocyanate The form which 2 types or 3 types of these mixed may be sufficient. Further, it is not necessary that all of X, Y, and Z are reactive substituents, and at least one of them may be a hydrolyzable group of, for example, the above-described halogen, alkoxy, hydroxy, acetoxy, amino, or isocyanic acid. However, in order to form a strong siloxane bond network, it is preferable that all of X, Y, and Z are the aforementioned reactive groups. Examples of the monovalent group when X, Y, and Z are not the above-described reactive groups include a hydrogen atom and an alkyl group having 1 to 5 carbon atoms.

  An example of such a silane coupling agent is commercially available under the trade name DSX (manufactured by Daikin Industries, Ltd.).

  The formation method of a silane coupling agent layer is not specifically limited, For example, normal coating methods, such as a spin coat method, a dip coat method, and a spray coat method, can be used. In application, the silane coupling agent may be appropriately diluted with a solvent.

  The silane coupling agent layer has a thickness comparable to a monomolecular film or an ultrathin film close thereto, and the thickness is about 1 to 20 nm.

  In addition, in order to satisfactorily perform the chemisorption reaction between the silane coupling agent and the surface layer 2s, the surface of the surface layer 2s is previously hydrophilized by a method such as plasma irradiation, corona discharge treatment, or electron beam irradiation. It is preferable.

Further, as a method for imparting water repellency, oil repellency, and lubricity to the surface of the optical information medium, a method of fluorinating the surface of the surface layer 2s by plasma treatment using a fluorine compound can also be preferably used. In this method, the surface layer 2s is surface-treated with plasma of a fluorine compound such as tetrafluoromethane. In this treatment, the surface layer 2s itself is fluorinated and / or the surface layer 2s is subjected to the surface treatment. Precipitation of the fluorine compound polymer proceeds. As the fluorine compound used, for example, organic fluorine compounds such as tetrafluoromethane (CF ₄ ) and tetrafluoroethylene (C ₂ F ₄ ), and inorganic fluorine compounds such as SF ₆ and NF ₃ are preferable.

In addition, a lubricant layer composed of a fluorine-based polymer such as perfluoropolyether, a silicone-based polymer such as polydimethylsiloxane, and the silane coupling agent is formed on the surface of the surface layer 2s by coating. A method of forming a strong chemical bond at the interface between the surface layer 2s and the lubricant layer by performing a discharge treatment can also be used. As a plasma supply source in the plasma discharge treatment, in addition to the above-mentioned various fluorine compounds, compounds not containing fluorine atoms, such as methane (CH ₄ ), ammonia (NH ₃ ), diborane (B ₂ H ₆ ), etc. It may be used. In addition, regarding the lubricant layer constituting material such as a fluorine-based polymer and a silicone-based polymer, the presence or absence of a reactive end group such as a carboxyl group, an isocyanate group, or an acryloyl group is not particularly limited. An example of a commercially available fluorine polymer is Fomblin Z60 manufactured by Augmont Co., Ltd., and an example of a commercially available silicone polymer is KF-96 manufactured by Shin-Etsu Chemical Co., Ltd.

  On the other hand, when the surface layer 2s itself has water repellency, oil repellency, and lubricity, the above surface treatment may not be performed. The case where the surface layer 2s itself has water repellency, oil repellency, and lubricity is, for example, the case where the surface layer 2s is formed using the following materials.

  The surface layer 2s itself having water repellency, oil repellency, and lubricity contains a compound having a polymer main chain, and the polymer main chain and / or side chain exhibits water repellency, oil repellency, and lubricity. To do. Specifically, for example, those in which a water-repellent / oil-repellent / lubricating group such as a perfluoroalkyl group is introduced into the side chain of a polymer compound such as polymethyl methacrylate, polycarbonate, and amorphous polyolefin are preferable. Further, a radiation curable resin such as an ultraviolet curable resin is used for forming the surface layer 2s, fine particles made of an inorganic substance or a resin are dispersed in the resin, and the surface of the fine particles is fluorinated carbonized. It may be modified with a substance containing a water-repellent / oil-repellent / lubricating substituent such as hydrogen. By applying and curing such a radiation curable resin, the surface layer 2s having water repellency, oil repellency, and lubricity can be formed. In this case, the preferable particle diameter of the fine particles and the preferable ratio of the fine particles in the surface layer 2s are the same as those in the case where the inorganic fine particles such as colloidal silica are dispersed in the surface layer 2s.

  By setting the translucent substrate as described above, an optical information medium having excellent fingerprint removability and practically sufficient wear resistance can be obtained.

Example 1 (Production of optical information medium with improved fingerprint removability)
An optical recording disk sample having the structure shown in FIG. 1 was produced by the following procedure. However, in sample No. 0, the translucent substrate 2 has a single layer structure.

Sample No. 0
A reflective layer made of Al ₉₈ Pd ₁ Cu ₁ (atomic ratio) was formed on the surface of a disk-shaped support base 20 (made of polycarbonate, diameter 120 mm, thickness 1.2 mm) on which the groove was formed by sputtering. The groove depth was λ / 6 expressed by the optical path length at the wavelength λ = 405 nm. The recording track pitch in the land / groove recording method was 0.3 μm.

Next, a second dielectric layer having a thickness of 20 nm was formed on the reflection layer surface by sputtering using an Al ₂ O ₃ target.

Next, a recording layer 4 having a thickness of 12 nm was formed on the surface of the second dielectric layer by sputtering using an alloy target made of a phase change material. The composition (atomic ratio) of the recording layer 4 was Sb ₇₄ Te ₁₈ (Ge ₇ In ₁ ).

Next, a first dielectric layer having a thickness of 130 nm was formed on the surface of the recording layer 4 by sputtering using a ZnS (80 mol%)-SiO ₂ (20 mol%) target.

  Next, a radical polymerization type ultraviolet curable resin solution (4X108E manufactured by Mitsubishi Rayon Co., Ltd., solvent is butyl acetate) was applied to the surface of the first dielectric layer by a spin coating method to form a resin layer.

  Subsequently, in vacuum (0.1 atm or less), a polycarbonate sheet (thickness: 100 μm) was placed on the resin layer as the translucent substrate 2. As the polycarbonate sheet, Pure Ace manufactured by Teijin Ltd. manufactured by the casting method was used. Next, after returning to the air, the resin layer was cured by irradiating with ultraviolet rays, thereby adhering the light transmissive sheet to obtain an optical recording disk sample.

Sample No. 1
An optical recording disk sample having the structure shown in FIG. 1 was produced by the following procedure.

  The polycarbonate sheet of sample No. 0 is used as the inner layer 2i, and an ultraviolet curable resin (SD318 manufactured by Nippon Kayaku Co., Ltd.) is applied onto the inner layer 2i by a spin coating method and cured by irradiating with ultraviolet rays. A hard coat layer was obtained. The thickness of the hard coat layer was 2.0 μm.

Next, an SiO ₂ layer having a thickness of 100 nm was formed on the surface of the hard coat layer by a sputtering method using an SiO ₂ target. Before forming the SiO ₂ layer, the surface of the hard coat layer was activated by plasma etching. In this sample, the hard coat layer and the SiO ₂ layer constitute the surface layer 2s.

Further, a silane coupling agent was chemically adsorbed on the surface of the SiO ₂ layer to obtain an optical recording disk sample. As the silane coupling agent, DSX (made by Daikin Industries, Ltd.) having a fluorinated hydrocarbon water- and oil-repellent group was used, and a 0.1% (mass percentage) perfluorohexane solution was applied by spin coating. Then, the SiO ₂ layer was chemically adsorbed by heating in air at 60 ° C. for 10 hours.

Sample No. 2 : Disc sample of the present invention The polycarbonate sheet of the above sample No. 0 was used as an inner layer 2i, and an ultraviolet curable resin in which colloidal silica was dispersed on the inner layer 2i, Desolite Z7503 (JSR Corporation) The product was applied by spin coating, dried at 60 ° C. for 3 minutes to remove the diluted solvent, and then cured by irradiation with ultraviolet rays to form a surface layer 2s. The film thickness after curing was 3.0 μm.

Next, a fluorine plasma treatment was performed on the surface of the surface layer 2s. Tetrafluoromethane (CF ₄ ) was used as the fluorine compound. After degassing the chamber inside the plasma processing apparatus, CF ₄ gas was introduced and the pressure was adjusted to 0.5 Pa. Next, an RF electric field was applied, and plasma treatment was performed at an output of 100 W. The treatment time was 3 minutes. After completion of the plasma treatment, the inside of the chamber was returned to normal pressure and the disk was taken out.

Sample No. 3
The polycarbonate sheet of sample No. 0 was used as the inner layer 2i, and an ultraviolet curable resin (HOD3200 manufactured by Nippon Kayaku Co., Ltd.) was applied as a primer on the inner layer 2i and cured by ultraviolet irradiation. The film thickness after curing was 0.5 μm.

  Next, a thermosetting silicone coating agent (Fressera D manufactured by Matsushita Electric Works Co., Ltd.) is applied on the primer layer by a spin coating method, and dried and cured by heating at 80 ° C. for 2 hours to obtain a surface layer. 2s was formed. The thickness of the surface layer 2s was 1.0 μm.

  The silicone-based coating agent has a structure in which lubrication and water / oil repellency groups are introduced into the silicon atoms of the organosilicon compound as the monomer component, and the cured film has a polysiloxane bond. It has a structure in which a lubricating and water / oil repellent group is fixed to a silicon atom through a chemical bond.

Sample No. 4
The polycarbonate sheet of sample No. 0 was used as the inner layer 2i, and a DLC thin film having a thickness of 360 nm was formed on the inner layer 2i by plasma CVD to form the surface layer 2s. Ethylene (C ₂ H ₄ ) was used as the process gas. After degassing the inside of the chamber of the plasma processing apparatus, ethylene gas was introduced and the pressure was adjusted to 0.5 Pa. Next, an RF electric field was applied, and film formation by CVD was performed at an output of 100 W. The treatment time was 3 minutes. After completion of film formation, the inside of the chamber was returned to normal pressure, and the disc was taken out.

Sample No. 5
An optical recording disk sample was prepared in the same manner as Sample No. 1 except that the silane coupling agent layer was not provided on the surface of the SiO ₂ layer.

Sample No. 6
The polycarbonate sheet of sample No. 0 is used as the inner layer 2i, and an ultraviolet curable resin (SD318 manufactured by Nippon Kayaku Co., Ltd.) is applied onto the inner layer 2i by a spin coat method, and cured by irradiation with ultraviolet rays. A surface layer 2s having a thickness of 2.0 μm was formed.

Next, a solution obtained by diluting a silicone oil (KF96 manufactured by Shin-Etsu Silicone Co., Ltd., viscosity 10000 cP) with butyl acetate is applied to the surface of the surface layer 2s by a spin coating method to form a layer having water repellency, oil repellency, and lubricity. An optical recording disk sample was obtained. The application amount of silicone oil was 32 mg / m ² , and the thickness of the formed layer was 33 nm.

Sample No. 7
The polycarbonate sheet of sample No. 0 is used as the inner layer 2i, and an ultraviolet curable resin (SD318 manufactured by Nippon Kayaku Co., Ltd.) is applied onto the inner layer 2i by a spin coat method and cured by ultraviolet irradiation to obtain a thickness. A surface layer 2s of 2.0 μm was formed.

Next, a solution obtained by diluting a perfluoropolyether derivative (Augmont Montfomblin ZDOL) with a fluorine-based solvent (Aumontmont H-GALDEN ZV100) is applied to the surface of the hard coat layer by a spin coat method to provide water and water repellency. An oil / lubricating layer was formed to obtain an optical recording disk sample. The coating amount of the perfluoropolyether derivative was 35 mg / m ² and the thickness of the formed layer was 19 nm.

Sample No. 8
An optical recording disk sample was prepared in the same manner as Sample No. 2 except that the fluorine plasma treatment was not performed.

Sample No. 9
Instead of the silane coupling agent DSX used in sample No. 1, trifluoromethyltrimethoxysilane (CF ₃ Si (OCH ₃ ) ₃ ) was used. The coating solution was prepared by dissolving trifluoromethyltrimethoxysilane in m-xylene hexafluoride so as to be 0.1% by mass. Other than this, an optical recording disk sample was prepared in the same manner as Sample No. 1.

Evaluation With respect to each of the above optical disk samples, the contact angle of water with respect to the surface of the translucent substrate and the rate of change (deterioration degree) thereof were measured by the following procedure.

First, a silicone rubber plug having an end face diameter of 16 mm is coated with a dry waste cloth (Bencott Lint Free CT-8 manufactured by Asahi Kasei Kogyo Co., Ltd.), and a pseudo fingerprint component 2. 0 mL was impregnated. This pseudo fingerprint component is obtained by adding 4.0 g of test powder 1 11th type Kanto loam defined in JIS Z8901 to 10 g of triolein and stirring well. The Kanto loam contains SiO ₂ , Fe ₂ O ₃ , Al ₂ O _{3 and the} like as main components, and its median diameter is 1.6 to 2.3 μm. Next, the end face of the silicone rubber stopper is pressed vertically against the surface of the light-transmitting substrate of each sample with a load of 4.9 N / cm ² across a cloth impregnated with a pseudo fingerprint component, and is slid 50 times in the radial direction of the sample. It was.

Next, the silicone rubber stopper and the waste were newly prepared, and the waste was impregnated with 2.0 mL of ethanol in the same manner as described above. After that, the end of the silicone rubber stopper is pressed with a load of ^2.5 N / cm ² with a waste impregnated with ethanol at a location previously rubbed with a waste containing triolein, and slid 20 times in the radial direction of the sample. It was.

Next, the waste was replaced with a new one, and ethanol was impregnated in the same manner as described above, and the same part was slid again 20 times. After ethanol was completely dried and static electricity was removed by a static eliminating blow, the contact angle was measured. The contact angle was measured using a contact angle meter CA-D manufactured by Kyowa Interface Science Co., Ltd. in an environment at a temperature of 20 ° C. and a relative humidity of 60%. The results are shown in Table 1. Table 1 also shows the change rate of the contact angle. This rate of change uses the initial contact angle and the contact angle after wiping off the pseudo fingerprint component (contact angle after sliding in Table 1),
(After sliding-initial) /% of the value calculated by initial.

  Moreover, the dynamic friction coefficient of the translucent base | substrate surface was measured in the following procedures. A tip made of nylon having a tip radius of curvature of 5 mm was produced, and this was brought into contact with the surface of the translucent substrate of each sample with a constant load, and the sample was rotated as it was at a constant speed. The dynamic friction coefficient was obtained from the load and torque at that time. For the measurement, a modified optical disk drive was used, and the nylon chip was attached to the optical head portion of the drive. Further, the torque applied to the tip when the nylon tip slides on the sample surface, that is, the frictional force Fd can be measured by a torque meter. In this measurement, the load (normal force Fp) for bringing the nylon tip into contact with the sample surface was 20 mN, and the linear velocity for rotating the sample was 1.4 m / s. The dynamic friction coefficient μ is obtained from Fd / Fp.

  Similar to the measurement of the contact angle, the dynamic friction coefficient was measured at the initial stage and after the pseudo fingerprint component was adhered and wiped off (after sliding). Table 1 shows the initial and post-sliding dynamic friction coefficients and the difference (change amount) between the two.

  As is clear from Table 1, in samples No. 1 and No. 2, the water-repellent / oil-repellent / lubricant substituents are fixed to the surface layer 2s (or the surface layer 2s itself is water-repellent / repellent). Therefore, the contact angle hardly deteriorates even when rubbed with a waste impregnated with triolein, and the dynamic friction coefficient hardly changes. On the other hand, samples No. 6 and No. 7 have a water-repellent / oil-repellent / lubricating property provided by a fluid lubricant layer provided on the surface. Decreases, and the dynamic friction coefficient increases. From this result, it is expected that when the fingerprint is attached, the fingerprint component and the lubricant are mixed, and it is difficult to wipe off the fingerprint. In sample No. 5, since the surface of the translucent substrate is made of a glass component, the initial contact angle is extremely small.

Example 2 (Method for evaluating fingerprint removability of optical information medium)
The fingerprint removability of the surface of the translucent substrate of Samples No. 0 to No. 9 prepared in the above Examples and Comparative Examples was evaluated by the following method.

  A pseudo-fingerprint component was prepared by adding 1.0 g of triolein to 10 g of methoxypropanol, and further adding 400 mg of test powder 1 type 11 Kanto loam defined in JIS Z8901 and stirring. This was designated as pseudo-fingerprint component 1. For comparison, a pseudo-fingerprint component to which no Kanto loam was added was also prepared. Further, for comparison, 200 mg of triolein was added to 5 g of methoxypropanol, 200 mg of keratin (derived from human epithelium, manufactured by Wako Pure Chemical Industries, Ltd.) was added, shaken vigorously, and allowed to stand for 10 seconds. Next, a supernatant portion where no keratin having a large particle diameter was present was gently collected and used as a pseudo fingerprint component 3.

  Next, about 1 mL of each pseudo-fingerprint component was sampled with good stirring with a magnetic stirrer and applied to a polycarbonate substrate (diameter 120 mm, thickness 1.2 mm) by spin coating. The substrate was heated at 60 ° C. for 3 minutes to completely remove methoxypropanol, which is an unnecessary diluent. This was used as a master plate for pseudo-fingerprint transfer.

  Subsequently, the end face (diameter 12 mm) of the No. 1 silicone rubber plug, which was uniformly polished with # 240 abrasive paper, was used as a pseudo-fingerprint transfer material. The pseudo fingerprint component was transferred to the end face of the transfer material by pressing with a load of 29 N for 10 seconds. Next, the pseudo fingerprint component was transferred by pressing the end face of the transfer material with a load of 29 N for 10 seconds on the surface of the translucent substrate of each sample. The fingerprint pattern was transferred to a position near the radius of 40 mm of the medium.

  Next, the pseudo fingerprint attached to each sample was wiped off by the following procedure. 8 layers of commercially available tissue paper (manufactured by Crecia Co., Ltd.) are placed between the larger end face (16 mm in diameter) of the No. 1 rubber stopper and the surface of the translucent substrate to which a pseudo fingerprint is attached. The sandwich was pressed with a force of 4.9 N. In this state, the pseudo fingerprint was wiped off by slowly moving from the center to the outer periphery of the sample.

  For each sample, the jitter of the recorded signal was measured at each time point before pseudo fingerprint attachment (initial stage), after pseudo fingerprint attachment, and after pseudo fingerprint wiping 2 times, 5 times, 10 times, and 15 times. . These results are shown in Table 2. Moreover, the result when using the pseudo fingerprint component 1 is shown in FIG.

  Various parameters and recording / reproducing conditions of the optical system of the optical information medium evaluating apparatus used for signal recording and reproducing are as follows.

Laser wavelength: 405 nm
Objective lens numerical aperture NA: 0.85,
Linear velocity: 6.5m / s
Recording signal: 1-7 modulation signal (shortest signal length 2T),
Recording area: land and groove (only the measurement result of the groove portion is shown in Table 2)

On the other hand, evaluation of sensory fingerprint removal ease (sensory test) was also performed. First, each pseudo fingerprint component was adhered to the surface of each sample under the above conditions. Subsequently, about these samples, 5 subjects selected arbitrarily conducted a wiping test, and the wiping ease was evaluated in three stages. The results are shown in Table 3. The evaluation criteria shown in Table 3 are:
A: Very easy to wipe fingerprints,
B: Easy fingerprint wiping,
C: It is difficult to wipe fingerprints,
It is. For wiping, commercially available tissue paper (manufactured by Crecia Co., Ltd.) was used, and the number of times of wiping and the load were not specified.

  In Table 1, in sample No. 1 to No. 4 in which the contact angle on the surface of the translucent substrate 2 and the rate of change thereof are within a predetermined range, as shown in Table 2 and FIG. Immediately after 5 times, the recorded signal jitter recovered to almost the same level as before the fingerprint attachment. On the other hand, the other samples, especially samples No. 6 and No. 7, have high water repellency, oil repellency, and lubricity, but the initial value is obtained even after 15 wiping operations. Until then, jitter has not recovered. From these facts, it is clear that the fingerprint removability is not simply dependent on the water / oil repellency, that is, the surface energy. In other words, even if the water and oil repellency is high, the water and oil repellency is absorbed by the lubricant layer provided on the surface and the water and oil repellant previously added to the translucent substrate material. When it is realized by a fluid material such as a layer that has come out, the fingerprint removability is rather deteriorated.

  On the other hand, when the evaluation was performed using a uniform pseudo-fingerprint component 2 that does not contain Kanto loam, as is apparent from the results shown in Table 2, the pseudo-fingerprint component was fixed on the surface of the translucent substrate 2. In any sample, the wiping property is almost the same. That is, in this case, the actual fingerprint attachment and removal cannot be reproduced and quantified, which is clearly inappropriate as a test method for optical information media.

  In sample No. 0, the initial contact angle in Table 1 is within a predetermined range, and there is almost no deterioration of the contact angle after sliding due to the pseudo fingerprint component. However, since the hardness of the translucent substrate surface is low, the surface is scratched by the wiping operation. For this reason, when wiping more than 10 times is performed, the jitter is worsened.

  On the other hand, as shown in Table 3, the fingerprint removability judged by the user sensuously does not necessarily match the order shown in Table 2. For example, when Samples No. 1 and No. 9 are compared, both are excellent in water repellency and oil repellency, and the surface hardness of the translucent substrate is also high. However, in Table 3, sample No. 1 is judged to be very easy to wipe fingerprints, whereas sample No. 9 is not necessarily judged to be easy to wipe fingerprints. This is because the dynamic friction coefficient of the surface of the translucent substrate 2 of Sample No. 9 is high. Therefore, it is clear from this result that not only the water / oil repellency and hardness but also the coefficient of dynamic friction must be reduced in order to improve the fingerprint removability judged sensuously by the user. It is.

  When the pseudo fingerprint component 3 containing keratin is used instead of the inorganic particulate matter, almost the same result as that obtained when the pseudo fingerprint component 1 is used is obtained. From this result, it is clear that the present invention using the pseudo fingerprint component containing the inorganic particulate matter can simulate the influence of the actual fingerprint attachment quantitatively and with good reproducibility.

It is sectional drawing which shows the structural example of an optical information medium. It is sectional drawing which shows the structural example of an optical information medium. It is a graph which shows the relationship between the frequency | count of wiping off the pseudo fingerprint adhering to the optical recording disk surface, and the jitter of an optical recording disk.

Explanation of symbols

2 translucent substrate 2i inner layer 2s surface layer 20 support substrate 4 recording layer 6 protective layer

Claims (5)

An optical information medium having an information recording layer on a support substrate and a translucent substrate on the information recording layer and used so that a recording / reproducing beam is incident on the information recording layer through the translucent substrate. ,
The translucent substrate includes an inner layer on the information recording layer side and a surface layer on the inner layer,
The surface layer includes a cured product of a radiation curable resin material, and inorganic fine particles are dispersed in the cured product.
At least a part of the surface of the translucent substrate contains fluorine atoms having no fluidity or silicone having no fluidity,
On the surface of the translucent substrate of the optical information medium, 0.4 parts by weight of Kanto loam of the 11th kind of test powder 1 specified in JIS Z8901 as a particulate material with respect to 1 part by weight of triolein as a dispersion medium. The following predetermined operations with pseudo fingerprint liquid containing:
(a) First, a silicone rubber stopper with a diameter of 16 mm on the end face is covered with dry waste, and a portion covering the vicinity of the end face of the silicone rubber stopper on the waste is impregnated with 2.0 mL of pseudo fingerprint liquid,
(b) Next, the end face of the silicone rubber stopper is pressed vertically against the surface of the light-transmitting substrate of the optical information medium with a load of 4.9 N / cm ² with a cloth impregnated with the pseudo-fingerprint liquid interposed therebetween. Slide 50 times in the radial direction,
After adhering by the following predetermined operations:
(c) First, prepare the same silicone rubber stopper as used in (a) above and the same waste as used in (a) above, and add ethanol 2 to the waste as in (a) above. Impregnating with 0 mL,
(d) Next, the end face of the silicone rubber stopper is vertically pressed at a load of ^2.5 N / cm ² with the waste impregnated with ethanol sandwiched between the places where the waste is slid in (b) above, and an optical information medium is obtained. 20 reciprocating slides in the radial direction of
(e) Further, replace the waste with a new one, and impregnate the waste with 2.0 mL of ethanol in the same manner as in (c) above.
(f) Again, the end face of the silicone rubber stopper was pressed vertically with a load of ^2.5 N / cm ² across the waste impregnated with ethanol at the location where the waste was slid in (d) above, and the optical information medium Slide 20 times in the radial direction,
(g) The ethanol on the surface of the light-transmitting substrate of the optical information medium is completely dried, and static electricity is removed by a discharge blow.
When the wiping operation of the attached pseudo-fingerprint liquid is performed, the dynamic friction coefficient of the surface of the translucent substrate after the wiping operation is applied to the surface of the translucent substrate of the optical information medium. An optical information medium in which contact is made at 20 mN and the optical information medium is measured by rotating the optical information medium at a linear velocity of 1.4 m / s, but does not increase by 0.1 or more with respect to the coefficient of dynamic friction before the pseudo-fingerprint liquid is attached. An optical information medium having an information recording layer on a support substrate and a translucent substrate on the information recording layer and used so that a recording / reproducing beam is incident on the information recording layer through the translucent substrate. ,
The translucent substrate includes an inner layer on the information recording layer side and a surface layer on the inner layer,
The surface layer includes a cured product of a radiation curable resin material, and inorganic fine particles are dispersed in the cured product.
At least a part of the surface of the translucent substrate contains fluorine atoms having no fluidity or silicone having no fluidity,
On the surface of the translucent substrate of the optical information medium, 0.4 parts by weight of Kanto loam of the 11th kind of test powder 1 specified in JIS Z8901 as a particulate material with respect to 1 part by weight of triolein as a dispersion medium. The following predetermined operations with pseudo fingerprint liquid containing:
(a) First, a silicone rubber stopper with a diameter of 16 mm on the end face is covered with dry waste, and a portion covering the vicinity of the end face of the silicone rubber stopper on the waste is impregnated with 2.0 mL of pseudo fingerprint liquid,
(b) Next, the end face of the silicone rubber stopper is pressed vertically against the surface of the light-transmitting substrate of the optical information medium with a load of 4.9 N / cm ² with a cloth impregnated with the pseudo-fingerprint liquid interposed therebetween. Slide 50 times in the radial direction,
After adhering by the following predetermined operations:
(c) First, prepare the same silicone rubber stopper as used in (a) above and the same waste as used in (a) above, and add ethanol 2 to the waste as in (a) above. Impregnating with 0 mL,
(d) Next, the end face of the silicone rubber stopper is vertically pressed at a load of ^2.5 N / cm ² with the waste impregnated with ethanol sandwiched between the places where the waste is slid in (b) above, and an optical information medium is obtained. 20 reciprocating slides in the radial direction of
(e) Further, replace the waste with a new one, and impregnate the waste with 2.0 mL of ethanol in the same manner as in (c) above.
(f) Again, the end face of the silicone rubber stopper was pressed vertically with a load of ^2.5 N / cm ² across the waste impregnated with ethanol at the location where the waste was slid in (d) above, and the optical information medium Slide 20 times in the radial direction,
(g) The ethanol on the surface of the light-transmitting substrate of the optical information medium is completely dried, and static electricity is removed by a discharge blow.
The contact angle of water (temperature 20 ° C., relative humidity 60% environment) after the wiping operation with the surface of the translucent substrate after the wiping operation of the attached pseudo fingerprint liquid is the contact before the pseudo fingerprint liquid is attached. An optical information medium that does not decrease by more than 15% with respect to the corner.   Before adhering the pseudo-fingerprint liquid, the dynamic friction coefficient of the surface of the translucent substrate (a nylon tip having a radius of curvature of 5 mm at the tip is brought into contact with the translucent substrate surface of the optical information medium at a load of 20 mN, and the optical information medium is moved to a linear velocity. The optical information medium according to claim 1 or 2, wherein (measured by rotating at 1.4 m / s) is 0.4 or less.   The light according to any one of claims 1 to 3, wherein a contact angle of water (at a temperature of 20 ° C and a relative humidity of 60%) is 75 ° or more before the pseudo-fingerprint liquid is attached. Information medium. The optical information medium according to claim 1, wherein the optical information medium is used in a system in which a minimum diameter of a recording / reproducing beam on the surface of a translucent substrate is 500 μm or less.

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