JP2002331594A - Storage medium substrate, storage medium comprising the substrate, and method for manufacturing storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage medium substrate having outstanding heat resistance, excellent surface smoothness, high rigidity and perfect flatness, and a storage medium comprising the storage medium substrate as well as a method for manufacturing the storage medium. SOLUTION: This storage medium substrate is formed of a polyphenylene sulfide resin composition and annealed at temperatures of 220 to 280 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage medium substrate having excellent heat resistance, surface smoothness, rigidity and flatness, a storage medium comprising the same, and a method of manufacturing the same. The present invention relates to a medium substrate, a storage medium using the same, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Polyphenylene sulfide resins have excellent heat resistance, rigidity, dimensional stability and flame retardancy, and are suitable for engineering plastics. It is widely used for applications such as parts, machine parts and automobile parts.

On the other hand, in the field of storage media, technology such as optical storage media, magneto-optical storage media, and magnetic storage media has been actively developed. As the storage capacity has increased, media media has been actively developed. Is underway.

In general, in the field of optical storage and magneto-optical recording, the use of resin around the lens and the disk substrate has been studied for the purpose of reducing the weight and improving the productivity. And optically transparent polycarbonates, cycloolefin polymers and cycloolefin copolymers.

On the other hand, in the case of a magnetic recording disk substrate represented by a hard disk, it is not necessary to be optically transparent, but a high level is required for the smoothness of the disk surface and the flatness of the disk. Or because heat resistance is required in NiP plating or sputtering process, etc.
At present, aluminum and inorganic glass are mainly used.

However, disk substrates using aluminum or inorganic glass are problematic in that the manufacturing process is complicated, productivity is poor, and the price is high. Therefore, in the future, hard disks will be transferred to AV (Audio Vis
ua) In order to apply it to devices and game machines and spread it, it is strongly desired to further improve the productivity of disk substrates and reduce the price, and to further increase the data capacity. I have.

[0007] Therefore, there is a movement to consider the use of such a disk substrate as a resin. However, polycarbonate, cycloolefin polymer, cycloolefin copolymer, and the like, which are used for compact disks for optical storage or magneto-optical storage, are used for hard disk substrates. If it is, it is excellent in surface smoothness, but low in rigidity and heat resistance and large in linear expansion coefficient, so it is inferior in dimensional stability due to use and environmental changes, so it is not practical There is no fact.

On the other hand, a method of annealing a molded body for the purpose of improving the heat resistance of a polyphenylene sulfide resin has been studied in the past, for example, Japanese Patent Application Laid-Open No. 54-146.
JP-A-867 and JP-A-57-164131 disclose a method of subjecting a polyphenylene sulfide molded body to a heat treatment at a temperature lower than the softening point. However, Japanese Patent Application Laid-Open Nos.
JP-A-164131 refers to performing heat treatment on a molded article made of a glass fiber-reinforced polyphenylene sulfide resin composition, and does not disclose any application to a storage medium substrate. No consideration is given to the surface smoothness, rigidity and flatness of the molded product required for the storage medium substrate.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in view of the above problems.
It is an object of the present invention to provide a storage medium substrate having excellent rigidity and flatness, a storage medium using the same, and a method for manufacturing the same. Particularly typically, it aims at providing a hard disk substrate made of a polyphenylene sulfide resin composition and having excellent heat resistance, surface smoothness, rigidity and flatness.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a substrate made of a polyphenylene sulfide resin composition is annealed under a specific temperature condition to obtain a hard disk. It has been found that heat resistance required at the time of manufacturing a storage medium can be imparted. Further, they have found that by selecting a specific inorganic filler, a storage medium substrate having excellent rigidity, surface smoothness and flatness can be obtained at the same time, and arrived at the present invention.

That is, the storage medium substrate of the present invention is a substrate made of a polyphenylene sulfide resin composition, and is characterized by being subjected to an annealing treatment at a temperature of 220 ° C. or more and 280 ° C. or less.

In the storage medium substrate of the present invention, the substrate is a molded product obtained by injection molding, and the polyphenylene sulfide resin composition is used in the amount of (B) based on 100 parts by weight of (A) polyphenylene sulfide resin. A) a composition comprising 0.05 to 400 parts by weight of an inorganic filler, wherein the polyphenylene sulfide resin composition is
As the inorganic filler (B), a fibrous filler having an aspect ratio: L (average fiber length) / D (average fiber diameter) of 10 or more is used in an amount of 10 parts by weight based on 100 parts by weight of the polyphenylene sulfide resin (A). The resin composition does not contain any of the above, and at least a part of the (B) inorganic filler is a non-fibrous inorganic filler having an average particle diameter of less than 1 μm. Preferred conditions include at least one inorganic filler selected from salts, sulfates, metal oxides and silicate-based materials, and the substrate being a substrate for a hard disk.

Further, a storage medium of the present invention is characterized by using the above-mentioned storage medium substrate, and is preferably used for an audio and / or video recording / distribution device or a game machine.

Further, the method for manufacturing a storage medium according to the present invention comprises:
A recording layer is formed on the recording medium substrate.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The storage medium substrate of the present invention will be described below.
A storage medium using the same and a method for manufacturing the same will be described in detail.

The (A) polyphenylene sulfide resin (hereinafter referred to as PPS resin) used in the present invention is a repeating unit represented by the following structural formula.

[0017]

Embedded image It is a polymer containing 70 mol% or more, preferably 90 mol% or more. When the repeating unit is less than 70 mol%, heat resistance tends to be impaired. In the PPS resin, 30 mol% or less of the repeating unit can be constituted by a repeating unit having the following structural formula.

[0018]

Embedded image Although the melt viscosity of the PPS resin used in the present invention is not particularly limited as long as melt kneading is possible, it is usually 2 to 5000P.
a · s (310 ° C., shear rate 1,000 / sec) is used, the range of 2 to 100 Pa · s is more preferable, and the range of 5 to 60 Pa · s is more preferable.

Such a PPS resin can be prepared by a generally known method, that is, a method of obtaining a polymer having a relatively small molecular weight described in JP-B-45-3368 or JP-B-52-1.
It can be produced by a method for obtaining a polymer having a relatively large molecular weight described in JP-A-2240 and JP-A-61-7332.

In the present invention, the PPS resin obtained as described above is subjected to a heat treatment in an atmosphere of an inert gas such as nitrogen or under reduced pressure, an organic solvent, hot water, or the like. Of course, it is also possible to use after subjecting to various treatments such as washing with an acid aqueous solution or the like, activation with a functional group-containing compound such as an acid anhydride, an amine, an isocyanate, or a functional group-containing disulfide compound.

As a specific method for cross-linking / high-molecular-weight PPS resin by heating, it is preferable to mix the oxidizing gas with an inert gas such as nitrogen or argon in an atmosphere of an oxidizing gas such as air or oxygen. A method in which heating is performed in a heating vessel at a predetermined temperature under a gas atmosphere until a desired melt viscosity is obtained can be exemplified. In this case, the heat treatment temperature is usually selected from the range of 150 to 280 ° C., preferably 200 to 270 ° C., and the treatment time is usually selected from the range of 0.5 to 100 hours, preferably 2 to 100 hours. Although it is about 50 hours, a target viscosity level can be obtained by controlling both. The heating device may be an ordinary hot-air dryer or a rotary heating device or a heating device with stirring blades. For efficient and more uniform treatment, a heating device with a rotary or stirring blade is used. Is more preferred.

When the PPS resin is heat-treated in an inert gas atmosphere such as nitrogen or under reduced pressure, a specific method is as follows.
Heat treatment temperature 150 to 280 ° C, preferably 200 to 2
70 ° C, heating time 0.5 to 100 hours, preferably 2 to 100 hours
A method of performing heat treatment under the condition of 50 hours can be exemplified. The heating device may be an ordinary hot air dryer or a rotary or a heating device with a stirring blade. However, if the treatment is to be performed efficiently and more uniformly, a heating device with a rotary or stirring blade may be used. More preferably, it is used.

As a specific method for washing the PPS resin with an organic solvent, the following method can be exemplified. That is, the organic solvent used for cleaning is PPS
There is no particular limitation as long as it does not have an action of decomposing the resin, for example, N-methylpyrrolidone, dimethylformamide, nitrogen-containing polar solvents such as dimethylacetamide, dimethylsulfoxide, sulfoxidesulfone-based solvents such as dimethylsulfone, acetone , Methyl ethyl ketone, diethyl ketone, ketone solvents such as acetophenone, dimethyl ether, dipropyl ether, ether solvents such as tetrahydrofuran, chloroform,
Methylene chloride, trichlorethylene, ethylene chloride,
Halogen solvents such as dichloroethane, tetrachloroethane and chlorobenzene, alcohol and phenol solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol and polyethylene glycol, and benzene, toluene, Examples thereof include aromatic hydrocarbon solvents such as xylene. Among these organic solvents, use of N-methylpyrrolidone, acetone, dimethylformamide, chloroform and the like is particularly preferable. These organic solvents are used alone or in combination of two or more.

As a method of washing with an organic solvent, there is a method such as immersing a PPS resin in an organic solvent.
If necessary, stirring or heating can be appropriately performed.
The washing temperature when washing the PPS resin with an organic solvent is not particularly limited, and an arbitrary temperature from ordinary temperature to about 300 ° C. can be selected. Although the cleaning efficiency tends to increase as the cleaning temperature increases, a sufficient effect is usually obtained at a cleaning temperature of normal temperature to 150 ° C. The PPS resin that has been subjected to the organic solvent washing is preferably washed several times with water or warm water in order to remove the remaining organic solvent.

As a specific method for treating the PPS resin with hot water, the following method can be exemplified. That is, it is preferable that the water to be used is distilled water or deionized water in order to exhibit a preferable effect of chemically modifying the PPS resin by washing with hot water. The operation of the hot water treatment is usually performed by adding a predetermined amount of PPS resin to a predetermined amount of water,
It is carried out by heating and stirring at normal pressure or in a pressure vessel. The proportion of the PPS resin and water is preferably as high as possible. Usually, a bath ratio of 200 g or less of the PPS resin to 1 liter of water is selected.

The following method can be exemplified as a specific method for treating the PPS resin with an acid. That is, there is a method of immersing the PPS resin in an acid or an aqueous solution of an acid, or the like, and if necessary, stirring or heating can be performed. The acid to be used is not particularly limited as long as it does not have a function of decomposing the PPS resin, and aliphatic saturated monocarboxylic acids such as formic acid, acetic acid, propionic acid and butyric acid, and halo-substituted aliphatic acids such as chloroacetic acid and dichloroacetic acid are used. Saturated carboxylic acid, acrylic acid, aliphatic unsaturated monocarboxylic acid such as crotonic acid, benzoic acid, aromatic carboxylic acid such as salicylic acid, oxalic acid, malonic acid, succinic acid, phthalic acid, dicarboxylic acid such as fumaric acid, and Inorganic acidic compounds such as sulfuric acid, phosphoric acid, hydrochloric acid, carbonic acid, and silicic acid. Among these acids, acetic acid and hydrochloric acid are more preferably used. The acid-treated PPS resin is
It is preferable to wash several times with water or warm water to remove the remaining acid or salt. The water used for washing is preferably distilled water or deionized water in the sense that the effect of the preferred chemical modification of the PPS resin by the acid treatment is not impaired.

The PPS resin composition for a storage medium substrate in the present invention may be composed of the above-mentioned PPS resin alone, but it is preferable to use an inorganic filler in combination to provide higher rigidity. Increasing the rigidity of the substrate is also effective for preventing blurring during rapid rotation and sudden stop of the substrate.

The inorganic filler (B) used in the present invention is classified into a fibrous material and a non-fibrous material.

Specific examples of the fibrous filler include glass fiber, calcium carbonate whisker, calcium silicate fiber (Walastenite whisker), calcium sulfate fiber,
Examples include carbon fibers, potassium titanate whiskers, zinc oxide whiskers, aluminum borate whiskers, aramid fibers, alumina fibers, silicon carbide fibers, ceramic fibers, and asbestos fibers.

However, the blending of the fibrous filler tends to impair the surface smoothness of the molded article. In addition, anisotropy of thermal expansion and thermal shrinkage is caused in the molded substrate, and the flatness tends to be impaired in a process requiring heating and cooling such as during molding of the substrate, annealing, or subsequent sputtering. Therefore, the fibrous filler is not blended, or even if it is blended, the compounding amount of the fibrous filler having an aspect ratio: L (average fiber length) / D (average fiber diameter) of 10 or more is particularly preferably: The amount is preferably less than 10 parts by weight based on 100 parts by weight of the polyphenylene sulfide resin.

Here, the average fiber length and average fiber diameter of the fibrous filler are values expressed by an average value obtained by observing an arbitrary 100 fibers with an optical microscope or an electron microscope.

The non-fibrous filler used in the present invention is other than the above-mentioned fibrous filler, and the non-fibrous filler may be any one of spherical, elliptical, cubic, plate-like and amorphous. May be used. Further, any of a synthetic filler and a natural filler may be used. Specific examples of such non-fibrous fillers include carbonates such as calcium carbonate and magnesium carbonate, sulfates such as calcium sulfate and barium sulfate, alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide and iron oxide. Metal oxides,
Silicate-based materials such as calcium silicate, magnesium silicate, aluminum silicate, silica, wollastenite, zeolite, mica, talc, kaolin, clay, pyrophyllite, glass beads, glass flakes, glass powder, magnesium hydroxide, aluminum hydroxide, etc. Hydroxide, ceramic beads, boron nitride, silicon carbide, graphite, carbon black, sericite, dolomite, and the like.

Of these, carbonates, sulfates, metal oxides and silicate-based materials are preferred, and precipitated calcium carbonate, barium sulfate and alumina are particularly preferred.

It is of course possible to use two or more of these inorganic fillers in combination.

The size of the non-fibrous inorganic filler used in the present invention is not particularly limited, but in order to obtain more excellent surface smoothness, at least a part of the filler has an average particle size of 1 μm.
m or less, and more preferably 0.8 μm or less. Here, the average particle size is a value represented by an average value obtained by observing an arbitrary 100 particles under an electron microscope. When the particle is not spherical or circular, the average value of the major axis and the minor axis is the value of the particle diameter.

When the inorganic filler (B) is blended, the amount of the inorganic filler is preferably (A) PP in view of the balance between surface smoothness and rigidity.
Usually, the range of 0.05 to 400 parts by weight is selected with respect to 100 parts by weight of the S resin, preferably 50 to 300 parts by weight, more preferably 80 to 250 parts by weight.

In many cases, the inorganic filler is used for improving the wettability with the resin component and preventing the filler particles from agglomerating.
Although the one whose surface is treated with an organic treating agent or the like is used, it is preferable to use an inorganic filler not treated with the organic treating agent in order to avoid deterioration of the smoothness of the molded substrate surface due to gas generation during molding. . Of course, a trace amount that does not affect the surface smoothness, for example, about 0.1% by weight or less, can be used.

Further, the PPS resin composition used in the present invention may be a polycarbonate resin, a polyphenylene ether resin, a polysulfone resin, a polyether sulfone resin, a polyarylate resin, as long as the effects of the present invention are not impaired. Polyetherimide resin, polyamideimide resin or cyclic polyolefin resin ("TOPAS" manufactured by Ticona, "APE" manufactured by Mitsui Chemicals, Inc.)
L ", Zeon Corporation" ZEONEX "," ZEONO
A "," ARTON "manufactured by Nippon Synthetic Rubber Co., Ltd.), etc., or an amorphous resin having a high glass transition temperature, or polybutylene terephthalate, polyethylene terephthalate,
Polyester such as polycyclohexyl dimethylene terephthalate and polyethylene naphthalate, nylon 6,
Polyamide such as nylon 66, nylon 610, nylon 11, nylon 12, semi-aromatic nylon, polyethylene tetrafluoride, polyetherketone, polythioetherketone, polyetheretherketone, epoxy resin,
Other resins such as phenolic resins, polyethylene, polystyrene, polypropylene, ABS resins, polyamide elastomers, polyester elastomers, polyalkylene oxides, and epoxy-modified olefin-based copolymers may be included.

The PPS resin composition used in the present invention contains a plasticizer such as a polyalkylene oxide oligomer compound, a thioether compound, an ester compound, an organic phosphorus compound or the like, as long as the effects of the present invention are not impaired. Crystal nucleating agents such as talc, kaolin, and organic phosphorus compounds, polyolefin compounds, silicone compounds,
Release agents such as long-chain aliphatic ester compounds and long-chain aliphatic amide compounds, antioxidants such as hindered phenol compounds and hindered amine compounds, heat stabilizers, calcium stearate, aluminum stearate, and lithium stearate And conventional additives such as silane coupling agents such as epoxy silane, amino silane, isocyanate silane and ureido silane, UV inhibitors, coloring agents, flame retardants and foaming agents. However, depending on the type of the additive, too much of the additive becomes a gas component and impairs the surface smoothness. Therefore, when the additive is added, not more than 1 part by weight based on 100 parts by weight of the (A) PPS resin component. Addition is preferred.

The method of preparing the PPS resin composition used in the present invention is not particularly limited, but the mixture of the raw materials is mixed with a generally known melt mixer such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, and a mixing roll. Supply 28
A method of kneading at a temperature of 0 to 450 ° C. can be mentioned as an example. The order of mixing the raw materials is also not particularly limited, and is a method in which all the raw materials are blended and then melt-kneaded by the above-mentioned method, and a part of the raw materials are melt-kneaded by the above method, and then the remaining raw materials are blended and melted. Kneading method,
Alternatively, any method may be used, such as a method in which some raw materials are blended and then the remaining raw materials are mixed using a side feeder during melt-kneading by a single-screw or twin-screw extruder. Further, as for the small amount of the additive component, it is of course possible to knead the other component by the above-mentioned method and the like to form a pellet, and then add it before molding to provide for molding.

As a method of molding a substrate such as a storage medium of the present invention, a method of injection molding the above PPS resin composition is mentioned as a preferable method. Optical disk technology can be used for this injection molding technology. In other words, a substrate such as a storage medium requires high precision molding technology such as dimensional accuracy and shape accuracy, and mold technology.
By combining the compression mechanism of the mold at the time of injection molding, it is possible to obtain a highly accurate molded product.

Molding of a substrate such as a resin storage medium is performed in comparison with the conventional substrate materials of aluminum and glass.
A disk molded product with good surface accuracy can be obtained in a short time by injection molding, so the grinding and polishing step of the substrate can be omitted, the disk substrate can be molded inexpensively, and the mastering technology, which is the optical disk molding technology, is used. By applying the information and recording necessary information in advance by a stamper or the like, a substrate such as a storage medium having a higher storage density can be obtained with high productivity and at low cost.

In addition to the advantage that the disk substrate can be manufactured at low cost, the storage medium using the resin substrate of the present invention also has advantages in that it is lightweight and excellent in quietness.

However, since the substrate obtained by injection molding as it is has insufficient heat resistance in the subsequent processing steps, the substrate obtained by molding is used in the present invention.
20 ° C or more and 280 ° C or less, more preferably 240 ° C
By performing the annealing treatment at a temperature of not less than 270 ° C. and not more than 270 ° C., it is possible to impart heat resistance required in a subsequent treatment process. If the annealing temperature is lower than the above range, the effect of improving the heat resistance is not recognized. If the temperature exceeds the above range, the substrate tends to be deformed, which is not preferable.

The annealing time is preferably selected from 0.5 to 100 hours, more preferably from 1 to 50 hours, and from 2 to 50 hours.
More preferred is 15 hours.

As an annealing method, there is a method in which a substrate is placed in a heating device controlled at a predetermined temperature and heated for a predetermined time. The heating device is not particularly limited, but an electric heating oven or an infrared heating furnace is used. Examples of the atmosphere for the annealing treatment include a hot air circulation system and a hot air circulation system.

In the annealing process, the substrate undergoes thermal expansion when the temperature rises, and contracts when the temperature falls. Further, crystallization of the PPS resin also proceeds. Due to such thermal expansion / shrinkage and crystallization, it is important to mix the inorganic filler with the above considerations in order to express high rigidity without impairing the surface smoothness and flatness. is there.

The storage medium of the present invention can be manufactured by forming a recording layer such as a magnetized film on a mirror portion of the storage medium substrate which has been molded and annealed as described above. Various methods such as NiP plating and sputtering can be used for forming the magnetized film.

The storage medium substrate and storage medium of the present invention
Since it has excellent heat resistance, surface smoothness, flatness and rigidity, it is used as a storage medium that requires a good appearance, especially as a substrate for hard disks, and because it is lightweight and excellent in quietness, It is extremely suitable as an audio and / or video recording / distribution device or a hard disk substrate for games.

[0050]

The present invention will be described in more detail with reference to the following examples.

The flexural modulus, average roughness Ra and flatness described in the examples and comparative examples were measured according to the following methods. [Measurement of Flexural Modulus] The measurement was performed according to ASTM D790. Specifically, the measurement was performed as follows. An injection molding machine (SG75-HIPRO) manufactured by Sumitomo-Nestal Co., Ltd. in which the resin composition pellets were set at a cylinder temperature of 320 ° C.
・ M III), injection pressure = molding lower limit pressure + 5 kg
Injection molding at f / cm ² gauge pressure, width 12.7m
A test piece of mx height 6.4 mm x length 127 mm was obtained.
Using this test piece, the measurement was performed in an atmosphere of 23 ° C. and a relative humidity of 50% under the conditions of a span of 100 mm and a strain rate of 3 mm / min. [Measurement of Surface Roughness (Center Line Average Roughness Ra)] 120 mm diameter × 1 m under the conditions of a cylinder temperature of 320 ° C., a mold temperature of 150 ° C., and a surface roughness Ra of a mold mirror surface of 0.02 μm.
A disk substrate having an m-thick mirror surface was formed. Scanning probe microscope (SPI3800 manufactured by Seiko Instruments Inc.) is used for any five of the mirror surfaces.
Using N), the center line average roughness Ra was measured, and the average value was defined as the average roughness Ra. The lower the value, the better the surface smoothness. [Measurement of flatness] Cylinder temperature 320 ° C, mold temperature 1
A disk substrate having a mirror surface portion having a diameter of 120 mm and a thickness of 1 mm was formed under the conditions of 50 ° C. and a surface roughness Ra of the mirror surface portion of the mold of 0.02 μm. Using this substrate, the flatness was measured without performing an annealing process or after performing a predetermined annealing process as needed.

That is, a jig was prepared which supports three points (positions at the apex of an equilateral triangle with the center of the substrate as the center of symmetry) about 5 mm inside from the periphery of the substrate. The substrate was placed on the jig in a state where it was supported at three points, and the substrate was treated at 240 ° C. for 5 minutes in a hot air flow type electric furnace. When the substrate surface temperature was measured, the substrate surface temperature gradually increased,
It was kept at 40 ° C. for 1 minute.

After this treatment, the substrate is placed on a flat glass plate, and the amount of deformation is measured at ten locations using a Digimatic height gauge manufactured by Mitutoyo Co., and the maximum value is used as a measure of flatness. did. When the planarity is extremely high, the deformation amount is zero. The larger this value is, the larger the deformation is, and the poorer the flatness is.

The ingredients used in the examples and comparative examples are as follows. [PPS resin (A)] PPS-1: Linear PPS resin M2 manufactured by Toray Industries, Inc.
888 PPS-2: Toray Industries, Inc. cross-linked PPS resin M2
100 [Inorganic filler (B)] Precipitated calcium carbonate: Non-fibrous filler having an average particle size of 0.2 μm (Shiraishi Kogyo: Brilliant-1500, synthetic inorganic filler not treated with any surface treatment agent or dispersant) ).

Barium sulfate: Non-fibrous filler having an average particle size of 0.7 μm (B55, manufactured by Sakai Chemical Industry, a synthetic inorganic filler not treated with any surface treating agent or dispersant).

Glass beads: non-fibrous filler having an average particle size of 5 μm (manufactured by Toshiba Barotini: MB-10, filler treated with a surface treatment agent and / or a dispersant).

Alumina: Non-fibrous filler having an average particle size of 1.0 μm (AL-43-L, manufactured by Showa Denko KK, inorganic filler not treated with a surface treatment agent or a dispersant).

Glass fiber: average fiber length 3000 μm, average fiber diameter 13 μm, (manufactured by NEC Glass: TN717,
Fillers that have been treated with surface treatment agents and / or dispersants). [Examples 1 to 6] After the PPS resin (A) and the inorganic filler (B) were dry-blended at the ratios shown in Table 1, 3
Melt kneading and pelletizing were performed by a twin screw type extruder set to 50 ° C. extrusion conditions. This was dried at 130 ° C. overnight to obtain a pellet.

From the pellets, test pieces or substrates used for the above-mentioned various evaluations were formed by injection molding.

The annealing treatment was performed by placing the molded product (substrate) on a flat metal plate and using a hot-air circulation type oven at the following predetermined temperature and time.

Condition A: (220 ° C. × 2 hours) → (240
° C × 2 hours) → (260 ° C × 2 hours) Condition B: (220 ° C × 2 hours) → (240 ° C × 2 hours)
→ (260 ° C. × 30 hours) Condition C: (200 ° C. × 6 hours) Table 1 shows the results of evaluating various physical properties of the obtained test piece and substrate. [Comparative Examples 1 to 6] Except that no annealing treatment was performed,
In the same manner as in Examples 1 to 5, melt mixing, pelletizing, drying, injection molding, and evaluation of physical properties were performed (Comparative Examples 1 to 5).

In addition, melt mixing, pelletizing, drying, injection molding, and evaluation of physical properties were performed in the same manner as in Example 2 except that the annealing temperature was set at 200 ° C. for 6 hours (Comparative Example 6).

The results are shown in Table 1.

[0064]

[Table 1] As is clear from the results in Table 1, the storage medium substrate of the present invention has excellent heat resistance, surface smoothness, rigidity, and flatness.

On the other hand, when the annealing treatment was not performed (Comparative Examples 1 to 5), when the substrate was treated at 240 ° C. while being supported at three points, the vicinity of the center of the substrate and between the supporting points were sunk, and it was apparent that The rigidity at the time of heat was insufficient. It is clear that the annealing treatment significantly improves this point.

The annealing temperature was 200 ° C. (Comparative Example 6)
Showed almost no effect of improving the rigidity under heat.

[0067]

As described above, according to the present invention,
A storage medium substrate having excellent heat resistance, surface smoothness, rigidity, and flatness and a storage medium made of the same can be obtained, and can be suitably applied particularly in the field of hard disk substrates.

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Claims (10)

[Claims] 1. A storage medium substrate comprising a polyphenylene sulfide resin composition, wherein the substrate is annealed at a temperature of 220 ° C. or more and 280 ° C. or less. 2. The storage medium substrate according to claim 1, wherein the substrate is a molded product obtained by injection molding. 3. The polyphenylene sulfide resin composition is a composition comprising (A) 100 to 100 parts by weight of polyphenylene sulfide resin and (B) 0.05 to 400 parts by weight of an inorganic filler. 3. The storage medium substrate according to claim 1, wherein: 4. The polyphenylene sulfide resin composition according to claim 1, wherein the (B) inorganic filler has an aspect ratio of L:
A fibrous filler having (average fiber length) / D (average fiber diameter) of 10 or more was mixed with (A) polyphenylene sulfide resin 100
The storage medium substrate according to any one of claims 1 to 3, wherein the resin composition does not contain 10 parts by weight or more based on parts by weight. 5. The inorganic filler according to claim 1, wherein at least a part of the inorganic filler (B) is a non-fibrous inorganic filler having an average particle diameter of less than 1 μm. Storage medium substrate. 6. The inorganic filler (B) is at least one inorganic filler selected from the group consisting of carbonates, sulfates, metal oxides and silicate-based materials.
6. The storage medium substrate according to claim 5. 7. The storage medium substrate according to claim 1, wherein said substrate is a substrate for a hard disk. 8. A storage medium using the storage medium substrate according to claim 1. Description: 9. The storage medium according to claim 8, wherein the storage medium is used for an audio and / or video recording / distribution device or a game machine. 10. The method for manufacturing a storage medium according to claim 8, wherein a recording layer is formed on the recording medium substrate according to any one of claims 1 to 6.