JPH0744913A - Protective self-adhesive sheet for magneto-optical recording medium and optical recording medium using the same - Google Patents

Abstract

PURPOSE:To improve sliding property against a magnetic head, environmental durability, and long-term reliability by laminating a protective self-adhesive sheet formed by using a crosslinking polymer material as the base material having a specified temp. or higher of glass transition temp. and initiation temp. of weight reduction by heating and having a specified range of the coefft. of linear expansion. CONSTITUTION:A photosetting resin compsn. and a self-adhesive agent are applied on the first supporting film 1. This compsn. has >=150 deg.C glass transition temp. and initiation temp. of weight reduction by heating and 0.00002-0.0002 coefft. of thermal expansion and is used as the crosslinking polymer material for the base material. The compsn. is irradiated with light and cured to form the base material 11. A self-adhesive layer 12 is applied on the second supporting film 2, cured, and laminated with the base material 11 to obtain a laminated sheet 5. Then, the film 2 is peeled and the laminated sheet is joined under pressure with a magneto-optical recording laminated substrate 13. This substrate 13 consists of Si3N4 dielectric films 22, 24 magneto-optical recording film 23 between the films 22, 24, and Al-Cr film 25 as the uppermost layer formed on a transparent resin substrate 21. Then, the film 1 is peeled to obtain a magneto-optical recording medium 16 having excellent sliding property against a magnetic head, environmental durability, and long-term reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective pressure-sensitive adhesive sheet for an optical recording medium capable of recording / reproducing / erasing with a light beam, and an optical recording medium using the same, particularly a magneto-optical recording medium. is there.

[0002]

2. Description of the Related Art Conventionally, as an optical recording medium, the following magneto-optical recording medium has been known as a typical one. That is, a dielectric material obtained by combining one or more inorganic dielectric materials such as Si ₃ N ₄ , SiO _x , ZnS, and SiC by a method such as vacuum deposition and sputtering on a resin substrate having a guide groove and a preformat signal. A body film is formed on which GdFe, TbFe, GdTbFe, T is formed.
An amorphous magneto-optical recording film such as bFeCo or GdTbFeCo is provided, a dielectric film similar to the inorganic dielectric film is formed on the magneto-optical recording film, and an ultraviolet curable resin is applied and cured on the dielectric film. However, a mechanical protective film is formed.

Examples of the conventional mechanical protective film have been disclosed in JP-A-63-217548 and JP-A-64.
-42043, JP-A-1-290117,
JP-A-2-30140, JP-A-3-62338, JP-A-4-64938 and the like are proposed.

Further, in the overwrite type recording / reproducing by the conventional magnetic field modulation method, the magnetic head slider loses its levitation force due to a decrease in the relative rotational speed at the beginning or the end of the driving of the magneto-optical recording medium, and the magnetic head is applied to the medium. As a method of preventing a head crash caused by the slider sliding directly, as a method of providing a slide resistant protective film that withstands the sliding of the magnetic head, a polymer sheet with lubricity is attached and A method of forming a protective layer of a recording medium is proposed in Japanese Patent Laid-Open No. 64-43834.

[0005]

However, in the overwrite type recording / reproduction by the conventional magnetic field modulation method, the magnetic head slider loses its levitation force due to a decrease in the relative rotational speed at the beginning or the end of the driving of the magneto-optical recording medium. The magnetic head slider is brought into direct sliding contact with the medium, and there is a problem that the magnetic head is worn and damaged, or the protective layer on the medium side is worn and damages the magneto-optical recording layer. . Further, the worn protective layer material adheres to the magnetic head, accumulates between the magnetic head and the protective layer, and both are attracted to each other, which makes it impossible to drive the magnetic head slider and the medium. .

An environmental durability test of the magneto-optical recording medium (for example, 80 ° C., 90% RH, 2000 hours test)
However, there was a problem that the recording / reproducing / erasing of the magneto-optical recording medium could not be performed, the C / N and the BER (bit error rate) were lowered, and the environmental durability was not good. .

Further, there is a problem that after the environmental durability test, the mechanical characteristics of the magneto-optical recording medium such as tilt and surface wobbling deteriorate, and recording / reproducing / erasing of the medium becomes impossible. It was

The present invention has been made to solve such conventional problems, and by using a specific protective adhesive sheet for an optical recording medium, magnetic head slidability, environmental durability, and long-term durability can be improved. It is an object of the present invention to provide an optical recording medium having excellent reliability.

[0009]

That is, the first invention of the present invention is a protective pressure-sensitive adhesive sheet for an optical recording medium, which comprises an adhesive layer formed on the surface of a substrate, wherein the substrate is (1) glass. Transition temperature (Tg) is 150 ° C. or higher, (2) Heating loss starting temperature is 150 ° C. or higher, and (3) Linear expansion coefficient is 0.00002 to
A protective pressure-sensitive adhesive sheet for an optical recording medium, which comprises a molded product using a cross-linking polymer material of 0.0002, and an optical recording medium having the protective pressure-sensitive adhesive sheet adhered thereto.

A second invention of the present invention is a protective pressure-sensitive adhesive sheet for optical recording medium, which comprises a substrate and an adhesive layer formed on the surface of the substrate, wherein the substrate has (1) a glass transition temperature (Tg). 1
50 ° C or higher, (2) elongation rate of 5 to 20%, (3) heating loss starting temperature of 150 ° C or higher, (4) acid value of 1 or lower,
(5) A protective pressure-sensitive adhesive sheet for an optical recording medium, which comprises a molded product using a cross-linking polymer material having a Cl ⁻ content of 5 ppm or less, and an optical recording medium having the protective pressure-sensitive adhesive sheet adhered thereto. Is.

The first aspect of the present invention will be described below. The first invention of the present invention is a protective pressure-sensitive adhesive sheet for an optical recording medium, comprising a pressure-sensitive adhesive layer to which an optical recording medium is attached, and a substrate having the pressure-sensitive adhesive layer formed on the surface thereof, which is used as the substrate. (1) Glass transition temperature (T
g) is 150 ° C or higher, preferably 160 to 250 ° C,
(2) Heating loss starting temperature is 150 ° C or higher, preferably 1
60 to 250 ° C, (3) linear expansion coefficient of 0.00002 to
A protective pressure-sensitive adhesive sheet for an optical recording medium, which comprises a molded product using a cross-linking polymer material of 0.0002, preferably 5 × 10 ⁻⁵ to 1 × 10 ⁻⁴ , and the protective pressure-sensitive adhesive sheet is adhered thereto. It is characterized by an optical recording medium.

The inventor of the present invention evaluated the magnetic head compatibility of the protective layer such as the occurrence of head crash between the magnetic head slider and the protective layer of the magneto-optical recording medium by a landing durability test. That is, this is a test in which the magnetic head slider adjusted to have a flying height of 1.6 μm on the protective layer of the magneto-optical recording medium rotated at 3000 rpm repeats landing and landing. By this test, the adhesion of dirt to the surface of the magnetic head slider and the scratch depth of the protective layer were evaluated, and the compatibility of the protective layer with the magnetic head was evaluated.

According to this test, the surface of the protective layer is required to have abrasion resistance, impact resistance and non-adhesiveness. In order to find a resin composition that satisfies these, the glass transition temperature (Tg), the coefficient of linear expansion, and the heating loss onset temperature are examined as the physical properties of the cured resin, and the resin composition that satisfies the physical properties of the present invention is used. I found a good thing.

Further, in order to examine the environmental durability, an environmental durability test (for example, 80 ° C., 90% RH, 2000 hours test) of an optical recording medium to which a protective pressure-sensitive adhesive sheet for an optical recording medium is adhered is performed and tested. The occurrence of pitting corrosion and the occurrence of defects in the front and rear recording layers are described in B. E. R (bit error rate) was measured and evaluated.

As a result, in addition to the above-mentioned physical properties such as Tg and linear expansion coefficient, the heating loss starting temperature of the cured resin is 1
It has been found that a resin composition having a temperature of 50 ° C. or higher may be used.

Tg of 150 ° C. satisfying these physical properties
The above is high and hard, the crosslink density is large, the coefficient of linear expansion is 0.00002 to 0.0002, and the toughness is also high.
The inventors have found a resin composition as shown below, which has little effect on pitting corrosion of the optical recording layer.

Examples of the cross-linking polymer material used in the present invention include materials having a functional group and capable of undergoing a cross-linking and curing reaction by heat, radiation such as light and electron beam, and polymerizing. However, a photo-curable resin composition that undergoes a cross-linking curing reaction by irradiation with light is preferable in that a curing reaction rate is particularly high and a material having high hardness can be obtained.

The photocurable resin composition is usually composed of (1) an oligomer component, (2) a monomer component, and (3) a photopolymerization initiator component. A known resin composition can be used for each of the above components (1), (2) and (3). In particular, the protective pressure-sensitive adhesive sheet for an optical recording medium and the environmental durability of the optical recording medium having the protective adhesive sheet attached thereto are used. , And the magnetic head compatibility to see the occurrence of head crash with the magnetic head, and the result of examining the correlation between the physical properties of the resin composition used for the protective adhesive sheet for optical recording medium, the resin composition and the physical properties I found that I could use what I was satisfied with,
The present invention has been completed.

(1) As the oligomer component, polyester acrylate, epoxy acrylate, polyether acrylate and the like can be mentioned, but urethane acrylate and polycarbonate acrylate which can impart toughness to the properties after crosslinking and have excellent durability are also used. It is preferable to use them alone or in combination.

As the monomer component (2), monofunctional acrylates, 2 to 6 functional acrylates and the like can be mentioned, but bifunctional acrylates are particularly preferable, and specific examples thereof include a cured molecular skeleton having excellent durability. Dicyclopentadiene diacrylate, which has excellent properties, is preferred. Further, it is suitable to use a pentafunctional or higher acrylate, preferably a urethane acrylate, which is capable of obtaining a resin hardened product having a high crosslinking density and a high hardness.

As a result of examining the blending amounts of (1) the oligomer component (2) and the monomer component satisfying the above-mentioned physical properties,
The following resin composition has been found.

That is, as an example of the cross-linking polymer material in the present invention, (a) urethane acrylate and / or polycarbonate acrylate 5 to 30 wt%, preferably 8 to 25 wt%, (b) bifunctional acrylate 2
It is preferable to use a resin composition containing 0 to 80 wt%, preferably 30 to 70 wt%, and (c) 1 to 5 wt% of a photopolymerization initiator.

Further, as another example of the crosslinkable polymer material in the present invention, (a) urethane acrylate and / or polycarbonate acrylate 5 to 30 wt%, preferably 8 to 25 wt%, (b) pentafunctional or higher acrylate 30 -80 wt%, preferably 35-75 wt%,
(C) Bifunctional acrylate 10 to 50 wt%, preferably 15 to 45 wt%, (d) Photopolymerization initiator 1 to 5 wt%
%, Is preferably used.

As the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer used in the present invention, conventionally known pressure-sensitive adhesives can be widely used, but acrylic ones are particularly preferably used.
Specifically, it is a homomonomer and a copolymer having acrylic acid ester as a main constituent monomer, and a mixture of these polymers. For example, as the acrylic acid ester of the monomer, ethyl methacrylate, butyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate methacrylate, and the like, and the above methacrylic acid replaced by acrylic acid, for example, can be preferably used.

The adhesive used in the present invention may also be a natural rubber type. As the natural rubber component, one having a diene bond and retaining tack in the presence of a tackifier (tackifier) component is used.

As the tackifier component used in the present invention, those composed of rosin-based resins, terpene-based resins, and petroleum resins such as aliphatic, alicyclic and aromatic resins are used. In addition, the method for curing the liquid pressure-sensitive adhesive composition is, for example, a method in which a conventionally known radical polymerization initiator is mixed and heated, a method in which a photopolymerization initiator is mixed, and UV light is irradiated, and an electron beam is irradiated. Etc. can be applied.

Next, the second invention of the present invention will be described. A second invention of the present invention is a protective pressure-sensitive adhesive sheet for an optical recording medium, which comprises an adhesive layer to which an optical recording medium is attached and a substrate having the adhesive formed on the surface thereof, wherein the substrate is crosslinked. A protective adhesive sheet for an optical recording medium, which is characterized by using a type polymer material, and an optical recording medium having the protective adhesive sheet adhered thereto.

As the cross-linking polymer material of the base material used in the present invention, a material having a functional group, which undergoes cross-linking and curing reaction by radiation such as heat light or electron beam to be polymerized, is used. However, a photo-curable resin composition that is cross-linked and cured by irradiation with light is preferable in that the curing reaction is particularly fast and a high hardness is obtained.

The photocurable resin composition comprises (1) an oligomer component, (2) a monomer component and (3) a photopolymerization initiator component. Known resin compositions can be used for the components (1), (2), and (3), and in particular, environmental protection of the protective pressure-sensitive adhesive sheet for optical recording medium and optical recording medium using the same, As a result of examining the correlation of the physical properties of the resin composition used, it was found that a resin composition satisfying the following physical properties should be used for the substrate, and the present invention was completed.

(1) Glass transition temperature (Tg) of substrate 15
It is 0 ° C or higher, preferably 160 to 250 ° C. (2) The elongation percentage of the substrate is 5 to 20%, preferably 8 to 18
%. (3) Heat loss starting temperature of the base material is 150 ° C. or higher, preferably 160 to 250 ° C. (4) Acid value of the base material is 1 or less, preferably 0.5 or less (5) Base material The Cl ^- content of is not more than 5 ppm, preferably not more than 3 ppm.

Examples of the resin composition satisfying the above (1) to (5) include a composition comprising (1) an oligomer component, (2) a monomer component, and (3) a photopolymerization initiator component. .

As the (1) oligomer component, (2) monomer component and (3) photopolymerization initiator component, the same ones as in the first invention are used, but the following compositions are preferable. It is mentioned as a thing.

(A) Urethane acrylate and / or polycarbonate acrylate 5 to 30 wt%, preferably 8 to 25 wt%, (b) Bifunctional acrylate 20 to
A resin composition containing 80 wt%, preferably 30 to 70 wt%, and (c) 1 to 5 wt% of a photopolymerization initiator.

(A) Urethane acrylate and / or polycarbonate acrylate 5 to 30 wt%, preferably 8 to 25 wt%, (b) pentafunctional or higher acrylate 3
0-80 wt%, preferably 35-75 wt%, (c)
Bifunctional acrylate 10 to 50 wt%, preferably 1
A resin composition containing 5 to 45 wt% and (d) 1 to 5 wt% of a photopolymerization initiator.

That is, in the cross-linked polymer material of the base material, (1)
Tg is 150 ° C or higher, and (2) elongation is 5 to 2
0%, a high hardness and tough resin cured product is used,
(3) A resin cured product having a small amount of uncured monomer components, which has a heating loss starting temperature of 150 ° C. or higher, has a low acid value of 1 or less, and has an impurity Cl ⁻ of 5 or less.
By using a protective adhesive sheet for optical recording media using the same as ppm, the environmental durability of the optical recording medium using the same, that is, reliability of recording / reproducing / erasing and tilt (Tilt) and surface. It can be made excellent without any change in mechanical characteristics such as runout.

As the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer in the present invention, conventionally known ones are widely used, but an acrylic pressure-sensitive adhesive having excellent adhesiveness and environmental durability is particularly preferable. In particular, an acrylic copolymer selected from a homomonomer having an acrylic ester as a main constituent monomer and a copolymer thereof, a copolymer with another functional monomer, and a mixture of these copolymers are preferable.

For example, as the acrylic acid ester of the monomer, ethyl methacrylate, butyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate methacrylic acid, etc., and the above-mentioned methacrylic acid are preferably used instead of acrylic acid. it can.

Further, the acid value of the pressure-sensitive adhesive used in these pressure-sensitive adhesive layers is 1 or less, and by using a low impurity Cl ⁻ of 5 ppm or less, it is possible to protect the optical recording medium using the pressure-sensitive adhesive. The environmental durability of the pressure-sensitive adhesive sheet and the optical recording medium to which the pressure-sensitive adhesive sheet is attached can be greatly improved.

The method for producing the protective pressure-sensitive adhesive sheet for an optical recording medium according to the first and second aspects of the present invention will be described below with reference to FIG.
And it demonstrates based on FIG. In FIG. 1, the first
On the supporting film 1 (polyester film) of No. 1, the resin composition is cured by a method such as heat, ultraviolet rays, and electron beams to form the base material 11 of the protective pressure-sensitive adhesive sheet for optical recording medium.
The laminated film 3 is prepared.

Next, a pressure-sensitive adhesive is applied on the second support film 2 (release film) to form a pressure-sensitive adhesive layer 12 to form a second laminated film 4. Further, the first laminated film 3 and the second laminated film 4 are subjected to dry lamination so that the base material 11 and the pressure-sensitive adhesive layer 12 are in contact with each other, and the laminated sheet 5 is prepared. The laminated sheet 5 with the first support film 1 and the second support film 2 peeled off is a protective pressure-sensitive adhesive sheet for an optical recording medium.

Next, as shown in FIG. 2, the second supporting film 2 is peeled off from the laminated sheet 5, and then it is attached onto the recording film of the magneto-optical recording laminated substrate 13. Then, the first support film 1 is peeled off to prepare the magneto-optical recording medium 16 having the protective adhesive sheet for optical recording medium formed on the recording film.

The magneto-optical recording laminated substrate 13 was prepared as shown in FIG. A dielectric film made of Si ₃ N ₄ (22) having a film thickness of 1000 Å is formed on the transparent resin substrate (21) on which the guide groove and the preformat signal are formed, and then an amorphous film having a film thickness of 200 Å is formed. TbFe
A magneto-optical recording film (23) made of Co-Cr is provided, a dielectric film made of Si ₃ N ₄ (24) having a film thickness of 400 Å is further formed, and an Al-Cr film (25) having a film thickness of 600 Å is further formed. Was deposited.

The total thickness of the base material and the pressure-sensitive adhesive layer of the protective pressure-sensitive adhesive sheet for an optical recording medium in the present invention is in the range of 3 to 15 μm, preferably 5 to 10 μm. If it is less than 3 μm, it is not preferable from the viewpoint of preventing scratches on the surface.
If it exceeds m, the distance between the magnetic head slider and the magneto-optical recording layer becomes large, low magnetic field recording cannot be performed, and the power consumption of the drive cannot be reduced, which is not preferable.

Regarding the constitution of the thickness of each layer of the protective pressure-sensitive adhesive sheet for optical recording medium, the thickness of the pressure-sensitive adhesive layer is preferably 1 to 8 μm, and the thickness of the substrate is preferably 2 to 14 μm. Further, as the constitution of the protective pressure-sensitive adhesive sheet for an optical recording medium, a resin composition obtained by blending a pressure-sensitive adhesive layer and a crosslinkable polymer material with conductive particles and / or a lubricant may be used.
It is also possible to use a laminate of more than one layer.

[0045]

EXAMPLES Examples of the present invention will be shown below and will be described more specifically. The physical properties of the crosslinked polymer material were measured by the following methods.

(1) Glass transition temperature (Tg) The peak of Tan σ was taken as Tg by dynamic viscoelasticity measurement. Measuring device: (Rheovibron DPVII Orientec Co., Ltd.) Measuring conditions: temperature rising rate 5 ° C / min, frequency 3.5 Hz,
Shearing method

(2) Linear expansion coefficient Measured by TMA (thermo-mechanical analysis). Measuring device: TMA-DII (manufactured by Seiko Denshi KK) Measuring conditions: temperature rising rate 5 ° C / min, 20 ° C to 200 ° C
Measured up to.

(3) Heating loss starting temperature Measured by thermogravimetric analysis (TG-DTA). Temperature rising rate 5 ℃
/ Min, measured from 20 ℃ to 300 ℃

Examples 1 to 4 and Comparative Examples 1 to 3 The photocurable resin compositions shown in Tables 1 and 2 below were used as the crosslinkable polymeric material for the substrate, and the adhesives shown below were used. As shown in FIGS. 1 and 2, the first support film 1 is coated with a photocurable resin composition shown in Tables 1 and 2 by a roll coater, and then is irradiated with light to be cured to form a substrate 1.
1 was prepared and a first laminated film 3 was prepared.

Next, the pressure-sensitive adhesive layer 12 was applied onto the second supporting film 2 by a roll coater and cured to form the second laminated film 4. Then, the 1st laminated film 3 and the 2nd laminated film 4 were dry-laminated, and the laminated sheet 5 was created.

Next, as shown in FIG. 2, the second supporting film 2 is peeled off from the laminated sheet 5 prepared in FIG.
The magneto-optical recording laminated substrate 13 was pressure-bonded. After that,
The first support film 1 was peeled off to obtain a magneto-optical recording medium 16.

The magneto-optical recording laminated substrate 13 was prepared as shown in FIG. On the transparent resin substrate (21) of the polycarbonate resin on which the guide groove and the preformat signal are formed, the S of 1000 Å film thickness is formed by the sputtering method.
A dielectric film made of i ₃ N ₄ (22) is formed, then a magneto-optical recording film (23) made of amorphous TbFeCo—Cr having a film thickness of 200 Å is provided, and further Si ₃ N _{4 having a} film thickness of 400 Å is provided.
A dielectric film made of (24) is formed, and a film thickness of 600
An Al-Cr film (25) made of Å was formed.

<Composition of pressure-sensitive adhesive> Monomer component: acrylic resin 2EHA (2-ethylhexyl acrylate) having the following composition 40 wt% isobutyl acrylate 40 wt% hydroxyethyl acrylate 14 wt% Polymerization initiator (benzoyl peroxide) 1 wt% vinyl acetate 5 wt% A 35% ethyl acetate solution containing the above acrylic resin was used.

[0054]

[Table 1]

[0055]

[Table 2]

The glass transition temperature (Tg), the coefficient of linear expansion, the heating loss starting temperature and the measurement results of the landing test of the optical recording medium of the photocurable resin compositions shown in Tables 1 and 2 above are shown in Table 3 below. .

[0057]

[Table 3] From the results of Table 3, in Examples 1 to 4, scratches did not occur even after 45,000 landing tests, whereas in Comparative Examples 1 to 3, scratches occurred.

Further, the environmental durability test of the optical recording media of Examples 1 to 4 and Comparative Examples 1 to 3 (80 ° C., 90% RH, 2
B. of about 000 hours). E. R (bit error rate)
The results of measuring changes are shown in Table 4.

[0059]

[Table 4] From the results in Table 4, in Examples 1 to 4, B. E. No deterioration of R was observed, but Comparative Examples 1 to 3
B. E. R greatly deteriorated.

Measuring Method (1) Landing Test The optical recording medium is rotated at 3000 rpm, the floating magnetic head is lowered onto the medium, and the flying height is kept at 1.6 μm for 1 second. After that, the head is raised and held for 1 second. A test in which this one cycle is repeated was conducted.

(2) Environmental durability test The above optical recording medium was tested at 80 ° C. and 85% R.V. H. It was put in a high temperature and high humidity tank.

(3) B. E. R (bit error rate)
Change The bit error rate (BER) before (0 hours) and after 2000 hours of the above environmental durability test was measured by a recording / reproducing evaluation device (LN31A, manufactured by Shibasoku Co., Ltd.).

Measurement conditions Recording pulse 85.3 nS Recording power 7.0 to 9.5 mW Erase power 9.0 mW Reproduction power 1.0 mW Recording erasure magnetic field 300 Oe

In Examples 5 to 9 and Comparative Examples 4 to 6 below, protective adhesive sheets for optical recording media were prepared using the photocurable resin compositions shown in Tables 5 and 6 below and the adhesives shown in Table 7. Created.

Example 5 As the photocurable resin composition, the composition of Table 7- was applied as the adhesive layer 12 onto the substrate 11 of the cured product of the composition of Table 5-, and the same procedure as in Example 1 was performed. A protective pressure-sensitive adhesive sheet for optical recording medium was prepared by the method described in 1.

Next, as shown in FIG. 6, a protective pressure sensitive adhesive sheet in which a pressure sensitive adhesive layer 12 is laminated on a substrate 11 which is the first substrate, and a magneto-optical recording laminated substrate 13 which is a second substrate. Were bonded by pressure bonding to obtain an optical recording medium. The magneto-optical recording laminated substrate was prepared in the same manner as in Example 1 (see FIG. 4).

Example 6 An optical recording medium was prepared in the same manner as in Example 5 except that the composition shown in Table 5 was used as the photocurable resin composition and the composition shown in Table 7 was used as the adhesive.

Example 7 An optical recording medium was prepared in the same manner as in Example 5 except that the composition shown in Table 5 was used as the photocurable resin composition and the composition shown in Table 7 was used as the adhesive.

Example 8 An optical recording medium was prepared in the same manner as in Example 5 except that the composition shown in Table 5 was used as the photocurable resin composition and the composition shown in Table 7 was used as the adhesive.

Example 9 An optical recording medium was prepared in the same manner as in Example 5 except that the composition shown in Table 5 and the composition shown in Table 7- were used as the photocurable resin composition.

Comparative Example 4 As shown in FIG. 5, protection made of a UV curable resin (SD-17, manufactured by Dainippon Ink and Chemicals, Inc.) on the magneto-optical recording laminated substrate 13 of Example 5. The film 31 was formed to prepare an optical recording medium.

Comparative Example 5 An optical recording medium was prepared in the same manner as in Example 5 except that the composition shown in Table 6- was used as the photocurable resin composition and the composition shown in Table 7- was used as the adhesive.

Comparative Example 6 An optical recording medium was prepared in the same manner as in Example 5 except that the compositions shown in Table 5 and the compositions shown in Table 7 were used as the photocurable resin composition.

[0074]

[Table 5]

[0075]

[Table 6]

[0076]

[Table 7]

The measurement results of the glass transition temperature (Tg), elongation (%), heating loss starting temperature (° C.), acid value and Cl ⁻ content of the photocurable resin compositions shown in Tables 5 and 6 above are shown. The results are shown in Table 8 below.

[0078]

[Table 8] The measurement results of the acid value and Cl ⁻ content of the pressure-sensitive adhesive composition shown in Table 7 above are shown in Table 9 below.

[0079]

[Table 9]

Methods for measuring physical properties (1) Glass transition temperature (Tg) As described above. (2) Elongation rate Autograph P-100 Tensile breaking elongation (%) was measured by a static tensile test method. (3) Heating loss starting temperature As described above. (4) Acid value (mgKOH / g) Measured by titration method. (5) Cl ⁻ content (ppm) Cl ⁻ ions in the resin composition were extracted and measured by ion chromatography.

Environmental durability tests (80 ° C., 90% RH, 2%, 2) of the optical recording media of Examples 5-9 and Comparative Examples 4-6.
B. of about 000 hours). E. R (bit error rate)
The results of measuring changes are shown in Table 10. Table 11 shows the results of measuring changes in tilt (Tilt) before and after the environmental durability test (80 ° C., 90% RH, 2000 hours).

[0082]

[Table 10]

[0083]

[Table 11]

Measuring Method (1) Tilt The tilt angle tilt (Tilt) was measured as the mechanical property of the optical recording medium using the optical disk mechanical property measuring device of Ono Sokki (LS-1000).

From the results of Tables 10 and 11, in Examples 5 to 9, B. E. Although the deterioration of R was not recognized, in Comparative Examples 4 to 6, B. E. R greatly deteriorated. Moreover, in Examples 5 to 9, the tilt (Ti
It) was not observed, but in Comparative Examples 4 to 6, the tilt (Tilt) was significantly deteriorated.

[0086]

As described above, the protective pressure-sensitive adhesive sheet for an optical recording medium of the present invention and the optical recording medium using the same can achieve the following effects. (1) It has excellent magnetic head sliding characteristics, and (2) it can maintain long-term reliability of recording / reproducing / erasing.
An optical recording medium having excellent environmental durability can be provided.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a method for producing a protective pressure-sensitive adhesive sheet for an optical recording medium according to the present invention.

FIG. 2 is a conceptual diagram showing a method of sticking a protective pressure-sensitive adhesive sheet according to the present invention on a magneto-optical recording laminated substrate.

FIG. 3 is a schematic diagram illustrating a magnetic field modulation recording method.

FIG. 4 is an explanatory view showing a magneto-optical recording laminated substrate.

FIG. 5 is an explanatory diagram showing an optical recording medium corresponding to a conventional comparative example 4.

FIG. 6 is a conceptual diagram showing an optical recording medium of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Base material 12 Adhesive layer 13 Magneto-optical recording laminated substrate 14 Floating type magnetic head 15 Laser light 16 Magneto-optical recording medium 21 Transparent resin substrate 22, 24 Si ₃ N ₄ 23 Magneto-optical recording film 25 Al-Cr film 31 UV resin Curing protective film 1 First supporting film 2 Second supporting film 3 First laminated film 4 Second laminated film 5 Laminated sheet

Claims (13)

[Claims] 1. A protective pressure-sensitive adhesive sheet for an optical recording medium, which comprises a pressure-sensitive adhesive layer formed on the surface of a substrate, wherein the substrate has (1) a glass transition temperature (Tg) of 150 ° C. or higher, and (2) a heating loss. Starting temperature is 150 ° C or higher, (3) linear expansion coefficient is 0.000
A protective pressure-sensitive adhesive sheet for an optical recording medium, comprising a molded product using a cross-linking polymer material having a size of 02 to 0.0002. 2. The cross-linking polymer material comprises (a) urethane acrylate and / or polycarbonate acrylate 5 to 30 wt%, and (b) bifunctional acrylate 20 to 8.
The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 1, which comprises a resin composition containing 0 wt% of (c) a photopolymerization initiator of 1 to 5 wt%. 3. The crosslinkable polymer material is (a) 5 to 30 wt% of urethane acrylate and / or polycarbonate acrylate, and (b) 30 or more trifunctional acrylate 30.
-80 wt%, (c) Bifunctional acrylate 10-50
The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 1, which comprises a resin composition containing 1 wt% to 5 wt% of (d) a photopolymerization initiator. 4. The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 2, wherein the bifunctional acrylate is dicyclopentadiene diacrylate. 5. A protective pressure-sensitive adhesive sheet for an optical recording medium, which comprises a pressure-sensitive adhesive layer formed on the surface of a substrate, wherein the substrate has (1) a glass transition temperature (Tg) of 150 ° C. or higher, and (2) an elongation percentage. Is 5 to 20%, (3) the heating loss starting temperature is 150 ° C or higher,
(4) A protective pressure-sensitive adhesive sheet for an optical recording medium, comprising a molded product using a cross-linked polymer material having an acid value of 1 or less and (5) a Cl ^- content of 5 ppm or less. 6. The crosslinkable polymer material comprises (a) urethane acrylate and / or polycarbonate acrylate 5 to 30 wt%, and (b) bifunctional acrylate 20 to 8.
The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 5, which comprises a resin composition containing 0 wt% of the photopolymerization initiator (c) and 1 to 5 wt%. 7. The cross-linkable polymer material comprises (a) urethane acrylate and / or polycarbonate acrylate in an amount of 5 to 30 wt%, and (b) a pentafunctional or higher acrylate 30.
-80 wt%, (c) Bifunctional acrylate 10-50
The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 5, which comprises a resin composition containing 1 wt% to 5 wt% of (d) a photopolymerization initiator. 8. The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 6, wherein the bifunctional acrylate is dicyclopentadiene diacrylate. 9. The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 5, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer made of a mixture of an acrylic acid ester polymer and an acrylic acid ester copolymer. 10. The pressure-sensitive adhesive layer (1) has an acid value of 1 or less,
(2) The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 5, comprising a pressure-sensitive adhesive having a Cl ⁻ content of 5 ppm or less. 11. The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 1, wherein the substrate has a thickness of 4 to 20 μm. 12. The protective pressure-sensitive adhesive sheet for an optical recording medium according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 2 to 8 μm. 13. An optical recording medium comprising the protective pressure-sensitive adhesive sheet according to claim 1 or 5 attached thereto.