JP3252525B2 - Information recording medium carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium carrier, and more particularly to an information recording medium such as a hard disk or a magneto-optical disk, a substrate thereof, or a production intermediate, a distribution intermediate, or a production intermediate thereof. And an information recording medium carrier that can withstand a degreasing cleaning treatment with a strong alkali.

[0002]

2. Description of the Related Art An information recording medium used for reading and writing information in a computer, a word processor, or the like is formed by stacking a recording layer such as a magnetic recording layer or an optical recording layer on a surface of a substrate such as aluminum, resin, or glass. is there.
In order to laminate a recording layer on a substrate, a sputtering method is generally used. At this time, if a small amount of salts, lipids, etc. adhere to the substrate surface, a problem occurs in the adhesion between the recording layer and the substrate,
A defect in the recording layer may cause a loss or an error of the recorded information. Therefore, as a pretreatment for lamination, degreasing and cleaning with freon has generally been performed. However, due to recent environmental problems, restrictions on the use of chlorofluorocarbons have become a social problem, and instead of chlorofluorocarbons, degreasing with a strong alkali has been studied. This degreasing with a strong alkali is usually carried out by immersing in an aqueous solution of about 20% by weight of sodium hydroxide heated to about 60 ° C. and performing ultrasonic cleaning for about 20 minutes.

On the other hand, the information recording medium substrate is usually stored in a cassette called a carrier for every fixed number of sheets, circulates, and moves as it is between processes and between processes. In each process, the information recording medium substrate is sometimes processed separately, that is, the leaf processing is performed one by one, but usually, in order to improve the efficiency, the batch processing is performed, that is, the processing is performed collectively. . For example, since a batch process is impossible in the sputtering process of the recording layer, a branching process is performed, and the aging process and the cleaning process after the sputtering process are often performed in a batch process. When performing a batch process, the process is performed while being stored in the carrier.

Accordingly, the carrier has a shape conforming to the standard of an automated information recording medium manufacturing apparatus, and a substrate or a manufacturing intermediate can be freely taken in and out of an automated apparatus when processing branches and leaves. In addition, it is required that foreign matter does not adhere to or scratch the substrate when the substrate is taken in and out, and that the substrate must withstand the drying process after the cleaning process. Therefore, the carrier is required to have dimensional precision and to have heat resistance enough to withstand the drying treatment. The carrier is preferably transparent so that the carrier can easily be checked for scratches and dirt.

As the material of the carrier, polycarbonate (PC), polyether imide (PEI), polyether ether ketone (PEEK) and the like have been used.
PEI and PEEK have excellent heat resistance, are suitable for aging treatment, and can withstand degreasing and washing with chlorofluorocarbons, but have insufficient transparency, so that adhesion of dirt or the like is difficult to visually recognize. On the other hand, PC has heat resistance that can withstand use and resistance to chlorofluorocarbon cleaning, is excellent in transparency, and is also excellent in precision moldability. Currently, PC carriers are common.
However, when the carrier made of PC is washed with alkali, it is easily adsorbed on the surface and is difficult to remove. Therefore, it is necessary to repeat the water washing process as rinsing, and the production efficiency is poor. In addition, the carrier is generally used repeatedly instead of being disposable, but there is a problem that the resin is likely to be deteriorated by repeatedly using the carrier for alkali washing.

[0006] Recently, thermoplastic norbornene-based resins have attracted attention as resins which can be injection-molded, are suitable for mass production, and have excellent heat resistance, moisture resistance, chemical resistance, transparency and the like. However, although it is known that it has excellent chemical resistance to organic solvents, etc., it is difficult to determine how resistant it is to strong alkalis used in the production of information recording media. It was not known how much the product could be removed by washing with strong alkali and then with water.

[0007]

As a result of intensive studies, the present inventors have found that a thermoplastic norbornene-based resin has excellent dimensional precision and resistance to strong alkali used in an information recording medium manufacturing process. The present inventors have found that the alkali adhering to the surface can be easily removed by washing with water and is excellent as a material for an information recording medium carrier, and have completed the present invention.

[0008]

Thus, according to the present invention, there is provided an information recording medium carrier whose surface in contact with an information recording medium, a substrate thereof, or a production intermediate thereof is made of a thermoplastic norbornene resin.

(Thermoplastic norbornene resin) The thermoplastic norbornene resin used in the present invention is disclosed in
No. 14,882, JP-A-3-122137, JP-A-4-63807, and the like. Specific examples thereof include a hydrogenated product of a ring-opening polymer of a norbornene monomer and a norbornene monomer. Addition polymers of the polymer, addition polymers of norbornene-based monomers and olefins, modified products of these polymers and hydrogenated polymers, and the like.

The norbornene-based monomer is also a monomer known in the above publication, JP-A-2-227424, JP-A-2-276842, etc., and includes, for example, norbornene, its alkyl, alkylidene and aromatic compounds. Substituted derivatives and halogens of these substituted or unsubstituted olefins,
Polar group substituents such as a hydroxyl group, an ester group, an alkoxy group, a cyano group, an amide group, an imide group, and a silyl group;
-Norbornene, 5-methyl-2-norbornene, 5,
5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methoxycarbonyl-
2-norbornene, 5-cyano-2-norbornene, 5
-Methyl-5-methoxycarbonyl-2-norbornene, 5-phenyl-2-norbornene, 5-phenyl-
5-methyl-2-norbornene or the like; a monomer obtained by adding one or more cyclopentadiene to norbornene, a derivative or a substitute thereof similar to the above, for example, 1,4: 5,8-dimethano-1,2,2 3,4,4a, 5,8,8a-2,3
-Cyclopentadienonaphthalene, 6-methyl-1,
4: 5,8-Dimethano-1,4,4a, 5,6,7,
8,8a-octahydronaphthalene, 1,4: 5,1
0: 6,9-trimethano-1,2,3,4,4a, 5
5a, 6,9,9a, 10,10a-dodecahydro-
2,3-cyclopentadienoanthracene and the like; a monomer having a polycyclic structure which is a multimer of cyclopentadiene, and derivatives and substituents similar to those described above, for example, dicyclopentadiene, 2,3-dihydrodicyclopentadiene Adducts of cyclopentadiene with tetrahydroindene, derivatives and substitutions thereof as described above, for example, 1,4
-Methano-1,4,4a, 4b, 5,8,8a, 9a-
Octahydrofluorene, 5,8-methano-1,2,2
3,4,4a, 5,8,8a-octahydro-2,3-
And cyclopentadienonaphthalene.

The polymerization of the norbornene-based monomer may be carried out by a known method. If necessary, the polymer can be copolymerized with another copolymerizable monomer or hydrogenated to obtain a thermoplastic saturated norbornene-based resin. It can be a hydrogenated thermoplastic norbornene-based polymer. Further, a polymer or a hydrogenated polymer is prepared by a method known in JP-A-3-95235 or the like, using an α, β-unsaturated carboxylic acid and / or a derivative thereof, a styrene-based hydrocarbon, an olefin-based unsaturated bond and a hydrolyzate. It may be modified using an organosilicon compound having a decomposable group or an unsaturated epoxy monomer.

The number average molecular weight measured by GPC (gel permeation chromatography) analysis using a toluene solvent is 100,000 to 200,000, and the weight average molecular weight is 2,000,000.
~ 600,000 is suitable, and preferably 2 to 2 in number average molecular weight.
If the molecular weight is smaller than this range, there are disadvantages such as insufficient strength and easy cracking. If the molecular weight is larger than this range, molding is not possible. Inconveniences such as poor fluidity at the time and difficulty in molding, and difficulty in synthesizing the resin with good reproducibility and productivity at the time of synthesizing the resin arise.

It is preferable that the olefinic polymer does not contain a large amount of olefinically unsaturated bonds from the viewpoints of being resistant to light deterioration, weathering deterioration, and degradation such as decomposition and coloring from various chemicals. When one or more carbon-carbon unsaturated bonds are present therein, it is preferable to carry out hydrogenation. In that case, the hydrogenation ratio is usually 90% or more, preferably 95% or more, more preferably 99% or more. Above.

The properties of the thermoplastic norbornene resin vary depending on the selection of monomers, molecular weight, modification reaction and the like.
As a molding material for a carrier, 18.6 kgf / cm
The deflection temperature under the load of ² is usually 60 ° C. or higher, preferably 90 ° C. or higher, more preferably 110 ° C. or higher. For that purpose, the glass transition temperature (hereinafter, referred to as Tg) needs to be usually 80 ° C. or higher, preferably 110 ° C. or higher, more preferably 130 ° C. or higher. When the molecular weight is within the above range, in order to raise Tg to 80 ° C. or higher, in the case of a homopolymer hydrogenated product, generally, a polymer of cyclopentadiene, a derivative or a substituted product thereof, cyclopentadiene and tetrahydroindene, etc. Addenda,
In the case of copolymers or copolymer hydrogenated products, generally 50% or more of the structural units derived from tetracyclic or higher monomers, using tricyclic or higher monomers such as derivatives and substituted products thereof. The polymerization may be carried out so as to contain more preferably 70% or more, particularly preferably 90% or more, or may be modified after the polymerization to have a similar structure. However, for the thermal efficiency of injection molding, Tg
Is preferably 200 ° C. or lower.

Although the specific gravity of the thermoplastic norbornene-based resin slightly varies depending on the type of the monomer and the like, it is generally 0.95 to 1.1.
It is.

Although the water absorption of the thermoplastic norbornene resin varies depending on the type of the monomer and the like, the water absorption of a homopolymer hydrogenated norbornene monomer having a polar group is 0.1%.
It is possible to synthesize a resin having a water absorption of 3% or less, 0.1% or less of a norbornene-based monomer homopolymer containing no polar group, and optionally 0.01% or less. A resin obtained by polymerizing a monomer containing no polar group has high hydrophobicity, and a contact angle of water of 50 ° or more, preferably 80 ° or more is possible. Suitable for molding materials.

The molding shrinkage of the thermoplastic norbornene resin is usually 0.7 to 0.9%, and the linear expansion coefficient is 6 to 8 ×
When it is in the range of 10 ^-5 / ° C. and further does not require transparency, by adding a filler or fiber as described below, the molding shrinkage is about 0.2% and the linear expansion coefficient is 2
It can be lowered to about × 10 ⁻⁵ / ° C., and from this point, it is suitable as a molding material for a carrier used in a process involving a temperature change.

Further, the thermoplastic norbornene resin is
Even if it contains organic impurities derived from the polymerization, hydrogenation and other treatments, it can be washed with an organic solvent such as water or alcohol after molding to remove organic substances on the surface. The amount of organic matter extracted per day in hot water is less than 500 μg / m ² in terms of the amount of organic carbon (TOC), and the amount of elution is practically not a problem. Substantially no trace of organic substances is eluted in the contacted liquid.

The thermoplastic norbornene-based resin may include, if desired, an antioxidant such as a phenol-based or phosphorus-based resin; a thermal degradation inhibitor such as a phenol-based resin; an ultraviolet stabilizer such as a benzophenone-based or hindered amine-based resin; an ester of an aliphatic alcohol; And auxiliary agents such as partial esters and partial ethers of polyhydric alcohols; antistatic agents such as fatty acid esters of polyhydric alcohols such as pentaerythritol monostearate; In addition, rubbers such as polybutadiene, polyisoprene, SBS, SIS, and SEBS, polystyrene, poly (meth) acrylate, polycarbonate,
Other resins such as polyester, polyether, polyamide, polyimide, polysulfone and the like can be mixed and used. Furthermore, when used for an information recording medium carrier that does not require transparency, various types of minerals such as talc and titanium white, and other fillers and fibers are used for the purpose of identification by color coding and improvement of heat resistance and strength. Also, organic or inorganic pigments and the like can be used.

(Information Recording Medium Carrier) In the present invention, the information recording medium is in the form of a plate, and a metal reflection film such as aluminum or gold is formed on a substrate; a magneto-optical recording layer such as a Tb—Fe—Co alloy; a magnetic recording layer of γ-Fe ₂ O ₃ , CrO ₂ or the like; Generally, the thickness is about 0.5 to 2.0 mm and the diameter is 1.5 inches, 2 inches, 2.5 inches, 3 inches, 3.5 inches, 4 inches, 5 inches, 6 inches, 8 inches, etc. Although it is circular, there are also things other than circular, such as a card-shaped rectangular one.

The information recording medium has a substrate made of aluminum,
There are various types such as glass and resin, but in the case of hard disks, which are typical examples of information recording media, those generally used as substrates are made of aluminum with a balance of lightness, physical strength, etc. It is.

As a method of laminating the recording layer on the substrate,
There are a coating method, a sputtering method, a vacuum deposition method and the like, and there is no particular limitation, but a sputtering method is generally used. If necessary, modify the surface of the substrate to improve the adhesion between the recording layer and the substrate, form a layer of a substance that easily adheres to the recording layer and the substrate between the recording layer and the recording layer, It may have a structure or a protective layer may be laminated on the recording layer. In the present invention, a cleaning-processed substrate, a surface-modified substrate, a substrate formed with a layer of a substance that easily adheres to both the recording layer and the substrate, or one of the multi-layered recording layers is used. A substrate that has been processed and is not completed as an information recording medium, such as a substrate having a laminated portion and a substrate before a protective layer has been laminated, is referred to as a production intermediate.

The information recording medium carrier of the present invention has a surface in contact with such an information recording medium, an information recording medium substrate, or an information recording medium manufacturing intermediate (hereinafter referred to as a substrate or the like) made of a thermoplastic norbornene resin. The substrate and the like can be held and removed without coming into contact with each other, and can be washed and dried while being stored in the carrier. Generally, substrates and the like can be accommodated in a parallel form without contacting each other, and can be taken in and out without contacting one by one in a direction parallel to the substrate.
As such a structure, generally, in a stored state,
The structure is such that the substrate and the like and the space are alternately stacked in layers, so that the substrate and the like do not move in directions other than the take-out direction. A space is provided between the substrates and the like by providing grooves, projections, and the like in the framework. further,
In order to make the washing process and the drying process efficient and as uniform as possible, in general, open the mouth so that liquid and air can flow into the space between the substrates and the like from directions other than the direction of taking out the substrates and the like. I have. As a specific example, FIG.
2 and 3 show a carrier having a structure shown in a front view, a side view, and a top view, respectively.

(Method of Forming Carrier) The carrier has a complicated shape. For example, a carrier manufactured by assembling metal parts may be coated with a thermoplastic norbornene resin to form the carrier. As a method for producing a product consisting solely of a thermoplastic norbornene-based resin, generally there is only a shaving process or an injection molding method, but either method may be used. From the viewpoint of mass productivity, a method of injection-molding a resin composed of only a thermoplastic norbornene resin is preferable.

As a method of injection molding, a very common injection molding machine can be used, and the temperature of the resin at the time of molding is generally about 200 to 350 ° C., and other conditions are general polystyrene and the like. Can be molded in the same setting as the above thermoplastic resin. Pre-drying or hopper dryer required for PC resin or the like may be used, but is not particularly required.

(Method of Using Carrier) In order to manufacture an information recording medium, it is usual to insert at least a substrate into a carrier, perform an alkali degreasing cleaning process, a rinsing process by washing with water, a drying process, and a manufacturing process from a carrier. It is necessary to carry out the steps of taking out the body, forming the recording film, inserting the substrate into the carrier, and aging.

The carrier of the present invention is made of a thermoplastic norbornene-based resin having excellent dimensional precision. By accurately molding the shape, the insertion of the substrate into the carrier and the removal of the production intermediate from the carrier are as follows. Even automated processing by machines can be processed without any problems. In addition, since this carrier is made of a thermoplastic norbornene-based resin, it has a high deflection temperature and Tg, is excellent in heat resistance, has a drying treatment,
Even in a heat treatment such as an aging treatment, the temperature is lower than Tg, preferably lower than Tg-10 ° C, and more preferably lower than Tg-20.
Can be used without deformation in an environment of less than about ° C.

The degreasing and washing treatment is generally performed at 50 to 70 ° C.
Then, the substrate is immersed in an aqueous solution of 15 to 25% by weight of sodium hydroxide and subjected to ultrasonic cleaning for 5 to 30 minutes. The thermoplastic norbornene-based resin has resistance to strong alkalis, and the carrier of the present invention is deformed, degraded,
Less likely to cause deterioration. Similarly, the carrier of the present invention is less likely to be deformed, deteriorated, deteriorated, or the like even by a cleaning treatment using chlorofluorocarbon or fluorocarbon substitute. In addition, when the carrier is taken out of the cleaning liquid after these cleaning treatments, the carrier is excellent in water sharpness and water repellency, and the cleaning liquid can be easily removed. Particularly, the cleaning liquid can be efficiently removed by ultrasonic cleaning using general pure water as a rinsing treatment. Usually, the rinsing process is performed about 1 to 4 times. When the number of times is large, the removal efficiency is excellent, but the production efficiency is inferior.

[0029]

The present invention will be described more specifically with reference to the following Reference Examples, Examples and Comparative Examples. The ultrasonic treatment in the ultrasonic cleaning was performed at 39 kHz and 100 W using an ultrasonic cleaning machine (UT-104, manufactured by Sharp).

Reference Example 1 6-methyl-1,4: 5,8-dimethano-1,4,4
a, 5,6,7,8,8a-A resin obtained by hydrogenating a ring-opening polymer of octahydronaphthalene (number-average molecular weight: 28,000, hydrogenation ratio: almost 100%, Tg140
° C) and 0.2 parts by weight of the phenolic antioxidant pentaerythrityl-tetrakis (3-
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) was added in an amount of 0.2 part by weight, and 240 parts were added using a twin-screw kneader (manufactured by Toshiba Machine Co., Ltd., TEM-35).
It pelletized by the method of melt extrusion at ° C.

Reference Example 2 The pellet obtained in Reference Example 1 was injection molded under the following conditions.
A test piece of 50 mm × 50 mm having a thickness of 3 mm was obtained. Molding machine: Mold clamping pressure 350 tons (Toshiba Machine Co., Ltd. I
S-350FB-19A) Resin temperature: 280 ° C Mold temperature: 100 ° C (fixed side), 100 ° C (movable side)

The specific gravity of this test piece was 1.01, 18.6 kg
f / cm ² load deflection temperature 120 ° C, molding shrinkage 0.7
%, Coefficient of linear expansion 7.0 × 10 ⁻⁵ / ° C., water absorption 0.007
%, A water contact angle of 89 °, and a light transmittance of 90% or more in a wavelength range of 400 to 700 nm.

The test piece was immersed in a 20% by weight aqueous solution of sodium hydroxide heated to 60 ° C. and subjected to ultrasonic cleaning for 20 minutes, followed by rinsing at 30 ° C. in 1 l of pure water. I went there. Thereafter, the appearance of the test piece was observed, but no change was observed from that before the treatment.

Example 1 The pellets obtained in Reference Example 1 were injection-molded under the same conditions as Reference Example 2, and front, side and side views are shown in FIGS. 1, 2 and 3, respectively.
A 2.5-inch disk carrier as shown in the top view was obtained.

This carrier is made of aluminum 2.5
The inch disk substrate was stored and left at a temperature of 70 ° C. for 30 minutes, but there was no abnormality.

Example 2 The carrier molded in Example 1 was immersed in a 20% by weight aqueous solution of sodium hydroxide heated to 60 ° C. and subjected to ultrasonic cleaning for 20 minutes. The immersion rinsing process was performed twice. Thereafter, the carrier was left in an oven at 40 ° C. for 2 hours and dried.

The dried carrier was immersed in 5 l of pure water at 60 ° C. and ultrasonically washed for 20 minutes.
Upon cooling to ° C, the pH was 6.6.

Further, washing, rinsing twice and drying were repeated 10 times, but no change in appearance was observed. Thereafter, the same apparatus as used for pure water ultrasonic cleaning for 20 minutes was used. Ultrasonic treatment was carried out at 60 ° C. and 5 l of pure water for 20 minutes under the same conditions as the ultrasonic cleaning. When the pure water was cooled to 25 ° C., the pH was 6.6.

In the same apparatus, ultrasonic treatment was carried out for 20 minutes at 60 ° C. and 5 l of pure water under the same conditions as in the ultrasonic cleaning.
Upon cooling to 5 ° C., the pH was 6.5. From this, it was found that the attachment and adsorption of sodium hydroxide to the carrier of the present invention were not recognized.

Comparative Example 1 A carrier of the same type was obtained in the same manner as in Example 1 except that a polycarbonate resin (AD5503, manufactured by Teijin Chemicals Ltd.) was used instead of the pellets obtained in Reference Example 1. The carrier was washed, rinsed twice, and dried as in Example 2.
The dried carrier was placed in the same apparatus as in Example 2 at 60 ° C., 5 l
After being immersed in pure water and ultrasonically washed for 20 minutes, the pure water was cooled to 25 ° C., and the pH was 8.1.

When the washing, rinsing, and drying processes were repeated 10 times, the carrier surface became cloudy and opaque.

[0042]

According to the present invention, it is possible to obtain an information recording medium carrier which is excellent in dimensional precision, is excellent in strong alkali washing resistance, has little adhesion and adsorption of strong alkali, and is easily removed.

[Brief description of the drawings]

FIG. 1 is a specific example of an information recording medium of the present invention,
It is a front view of the carrier used in the example of the present invention.

FIG. 2 is a specific example of an information recording medium of the present invention,
FIG. 3 is a side view of the carrier used in the example of the present invention.

FIG. 3 is a specific example of the information recording medium of the present invention,
FIG. 3 is a top view of a carrier used in an example of the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-59196 (JP, A) JP-A-6-336508 (JP, A) JP-A-5-206256 (JP, A) 206704 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/26 C08G 61/08 C08K 11/00

Claims (2)

(57) [Claims] 1. An information recording medium carrier whose surface in contact with an information recording medium, a substrate thereof, or a production intermediate thereof is made of a thermoplastic norbornene resin. 2. The information recording medium carrier according to claim 1, wherein the thermoplastic norbornene resin has a number average molecular weight of 10,000 to 200,000.