JP2011070714A - Support for magnetic recording medium and magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a support for a magnetic recording medium provided with excellent stability in size by reducing a humidity expansion coefficient of a width direction. <P>SOLUTION: In the support for the magnetic recording medium, a reinforced film layer (layer M) composed of metals or metallic inorganic compounds is provided on at least either face of thermoplastic resin film layers (layers F). The humidity expansion coefficient of the length direction and width direction of a film is 0 to 5 ppm/% RH. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a support for a magnetic recording medium comprising a thermoplastic resin film and a metal-based reinforcing film layer that can be suitably used for a base film such as a high-density magnetic recording tape for digital data.

  In recent years, the width of data tracks has become very narrow in magnetic tapes, especially data tapes that perform magnetic recording at high density, and slight thermal and mechanical dimensional changes during tape running and storage, Due to the difference in humidity environment during recording and reading, there has been a problem that data reproduction failure is caused. Therefore, a magnetic recording medium compatible with high-density recording is required to have high dimensional stability against environmental changes such as humidity and stresses such as heat and tape tension. In particular, a linear recording type data tape requires high dimensional stability in the tape width direction.

  Conventionally, as a material for magnetic tape, polyethylene-2,6-naphthalenedicarboxylate (hereinafter sometimes referred to as PEN) is used in addition to polyethylene terephthalate (hereinafter sometimes referred to as PET). I came. In particular, polyethylene-2,6-naphthalenedicarboxylate has mechanical properties, dimensional stability, and heat resistance superior to those of polyethylene terephthalate, and is a demanding application such as a support for high-density magnetic recording media. Is used. However, the demand for dimensional stability in high-density magnetic recording media and the like in recent years has been increasing, and in particular, reduction of the humidity expansion coefficient in the width direction of the magnetic tape has been demanded.

Therefore, in Patent Documents 1 and 2, as a support that can meet the above-described requirements for dimensional stability, a support for a magnetic recording medium in which a reinforcing film made of a metal material such as metal or semimetal is provided on a polyester film, or this support Magnetic recording media using a body have been proposed.
However, when the support described in these patent documents is actually used, even if the humidity expansion coefficient in the width direction is small, the dimensional stability is still insufficient.

JP 2006-216194 A JP 2006-216195 A

  An object of the present invention is to provide a support for a magnetic recording medium having a small humidity expansion coefficient in the width direction and excellent dimensional stability.

  In order to solve the above-mentioned problems, the present inventors first conducted intensive research on the above-mentioned Patent Documents 1 and 2, and when forming a reinforced film by vacuum deposition or the like, the humidity expansion coefficient (αh) in the width direction is small. That is, it can be understood that a biaxially oriented polyester film in which molecular chains are highly oriented in the width direction is used.

  However, because it is a highly oriented biaxially oriented polyester film, there is a large difference in the orientation of molecular differences due to slight differences in the heat and tension applied during vacuum deposition. It was found that the expansion coefficient varies greatly locally.

  Therefore, the present inventors conducted further research, and by reducing the humidity expansion coefficient in the longitudinal direction of the film, the variation of the humidity expansion coefficient can be extremely reduced, resulting in excellent dimensional stability. The present invention has been found.

Thus, according to the present invention, there is provided a support for a magnetic recording medium in which a reinforcing film layer (M layer) made of a metal or a metal-based inorganic compound is provided on at least one surface of a thermoplastic resin film layer (F layer). And
There is provided a support for a magnetic recording medium having a humidity expansion coefficient of 0 to 5 ppm /% RH in the longitudinal direction and the width direction of the support.

  Moreover, according to this invention, as a preferable aspect of this invention, the thickness of M layer is the range of 10-150 nm, the thickness of F layer is the range of 3-5 micrometers, M layer is Al. , At least one metal selected from the group consisting of Si, Cu, Zn, Ti, Ni and Co or a metal-based inorganic compound, M layer provided on both sides of the F layer, thermoplastic resin There is also provided a support for a magnetic recording medium comprising at least one selected from the group consisting of polyetheretherketone, syndiotactic polystyrene and polyphenylene sulfide.

  Furthermore, according to the present invention, there is also provided a magnetic recording medium comprising the support for magnetic recording medium of the present invention and a magnetic layer formed on at least one surface thereof.

  The support for a magnetic recording medium of the present invention has a low humidity expansion coefficient (αh) not only in the width direction but also in the longitudinal direction. A magnetic recording medium having dimensional stability can be manufactured.

  The support for a magnetic recording medium of the present invention is for a magnetic recording medium in which a reinforcing film layer (M layer) made of a metal or a metal-based inorganic compound is provided on at least one surface of a thermoplastic resin film layer (F layer). It is a support body, Comprising: The humidity expansion coefficient of the longitudinal direction and the width direction of a support body is 0-5 ppm /% RH.

  When the humidity expansion coefficient in the width direction of the support exceeds the upper limit, it becomes difficult to reduce the variation, and even if the variation can be reduced, only a support for a magnetic recording medium having insufficient dimensional stability can be obtained. The lower limit is not particularly limited, but 0.1 ppm /% RH or more is preferable because the film forming conditions do not have to be severe. The average humidity expansion coefficient in the width direction of the preferred support is in the range of 0.1 to 0.8 ppm /% RH, more preferably 0.1 to 0.7 ppm /% RH.

  Further, if the humidity expansion coefficient in the longitudinal direction of the support exceeds the upper limit, the difference between the maximum value and the minimum value tends to increase, and only a support for magnetic recording media with insufficient dimensional stability can be obtained. The lower limit is not particularly limited, but is preferably 0.1 ppm /% RH or more because it is easy to relax even if the difference between the maximum value and the minimum value is somewhat large. The average humidity expansion coefficient in the width direction of the preferred support is in the range of 0.1 to 0.8 ppm /% RH, more preferably 0.1 to 0.7 ppm /% RH. In the case of a linear recording type magnetic recording medium, the track is arranged in the width direction of the support, and the longitudinal direction of the support is the traveling direction in which the magnetic tape travels. However, it was considered that problems such as track misalignment did not occur and dimensional stability was not affected. However, in the present invention, it has been found that the variation of the humidity expansion coefficient in the width direction can be reduced by reducing the humidity expansion coefficient in the longitudinal direction.

  From such a viewpoint, when 10 points are measured at intervals of 5 cm in the width direction of the support, the difference between the maximum value and the minimum value of the humidity expansion coefficient in the width direction is preferably 1 ppm /% RH or less. When the difference between the maximum value and the minimum value is less than or equal to the above range, dimensional stability against environmental changes can be expressed to a higher degree. The difference between the maximum value and the minimum value of the humidity expansion coefficient in the width direction of the preferable support is 0.8 ppm /% RH or less, and further 0.7 ppm /% RH or less. The lower limit is not particularly limited and is preferably closer to 0. From the same viewpoint, the difference between the maximum value and the minimum value of the humidity expansion coefficient in the longitudinal direction is also preferably 1 ppm /% RH or less. When the difference between the maximum value and the minimum value is less than or equal to the above range, dimensional stability against environmental changes can be expressed to a higher degree. The difference between the maximum value and the minimum value of the humidity expansion coefficient in the longitudinal direction of the preferred support is 0.8 ppm /% RH or less, and further 0.7 ppm /% RH or less. The lower limit is not particularly limited and is preferably closer to 0.

  By the way, in order to produce a support for a magnetic recording medium having such a coefficient of humidity expansion, both the film forming direction and the width direction humidity are obtained by a method based on stretching conditions in which the molecular chains of the F layer are highly oriented. Since it is difficult to reduce the expansion coefficient, a method of selecting a thermoplastic resin that can reduce the humidity expansion coefficient without employing harsh stretching conditions as the F layer is preferable.

  From such a viewpoint, it is preferable to use at least one selected from the group consisting of syndiotactic polystyrene, polyether ether ketone, and polyphenylene sulfide as the thermoplastic resin in the present invention.

  The syndiotactic polystyrene (hereinafter sometimes referred to as SPS) in the present invention is a polystyrene having a syndiotactic structure as a stereochemical structure and is measured by a nuclear magnetic resonance method (13C-NMR method). It is preferable that the city is 75% or more, preferably 85% or more for dyad (2 constituent units), and 30% or more, preferably 50% or more for pentad (5 constituent units).

  Examples of such SPS include polystyrene, poly (alkyl styrene), poly (methyl styrene), poly (ethyl styrene), poly (propyl styrene), and poly (butyl styrene). Among these, polystyrene, poly (p -Methylstyrene), poly (m-methylstyrene), and poly (p-tertiarybutylstyrene) are preferably exemplified. SPS has a number average molecular weight of 10,000 or more, preferably 50,000 or more. When the number average molecular weight is less than the lower limit, heat resistance and mechanical properties are insufficient. On the other hand, the upper limit of the number average molecular weight is preferably 500,000 or less. When this upper limit is exceeded, film-forming property may become poor.

As the polyether ether ketone (hereinafter sometimes referred to as PEEK) in the present invention, the main structural unit is —O— (C ₆ H ₄ ) —O— (C ₆ H ₄ ) —C (O) —. A polymer composed of (C ₆ H ₄ )-. These polymers are known per se as described in JP-B-60-32642, JP-B-61-1486, JP-A-57-137116, and the like. Can be manufactured. PEEK in the present invention is 50 to 1000 Pa · s (500 poise to 10000 poise), more preferably 100 to 500 Pa · s (1000 poise to 5000 p) under conditions of an apparent melt viscosity of 380 ° C. and an apparent shear rate of 1000 sec ^−1. Those in the range of (poise) are preferable from the viewpoint of film forming properties and film characteristics.

  In the present invention, polyphenylene sulfide (hereinafter sometimes referred to as PPS) refers to a polymer having a repeating unit of 80 mol% or more, preferably 90 mol% or more of a structural unit represented by the following general formula.

If the polymer component composed of the structural unit represented by the above general formula is less than 80 mol%, the crystallinity, softening point, etc. of the polymer are lowered, and the heat resistance, dimensional stability and mechanical properties of the resulting film are impaired. If the repeating unit is less than 20 mol%, preferably less than 10 mol%, a unit containing a copolymerizable sulfide bond may be contained. The copolymerization method of the polymer may be random or block.
These SPS, PEEK and PPS can be produced by a method known per se.

  Further, the thermoplastic resin in the present invention includes a stabilizer such as an ultraviolet absorber, an antioxidant, a plasticizer, a lubricant, a flame retardant, a release agent, a pigment, a nucleating agent, as long as the effects of the present invention are not impaired. You may mix | blend a filler or glass fiber, carbon fiber, layered silicate, etc. as needed. In particular, the thermoplastic resin in the present invention preferably contains inert particles or the like as a lubricant from the viewpoints of running properties and winding properties when formed into a film.

[the film]
The thermoplastic resin film layer (F layer) in the present invention is a film layer formed of the above-mentioned thermoplastic resin and oriented uniaxially or biaxially, and is not limited to a single layer but is a film of two or more layers. A laminated film having layers may be used.

  By the way, in this invention, a surface direction is the direction of the surface orthogonal to the thickness direction of F layer or a support body. The film forming direction is the vertical direction, longitudinal direction or machine direction (MD direction) of the F layer or the support, and the width direction is orthogonal to the film forming direction (MD) of the F layer or the support. It is a direction and is referred to as a transverse direction or a transverse direction (TD direction).

[M layer]
The support of the present invention is a support in which a reinforcing film layer (M layer) made of a metal or a metal-based inorganic compound is provided on at least one surface of a thermoplastic resin film layer (F layer). In the case where the M layer is not provided, even if the humidity expansion coefficient can be reduced, the magnetic tape is stretched due to tension or the like when the magnetic tape is run, and the effect of the present invention cannot be obtained. That is, by having the M layer, it is possible to achieve both a preferable range of a change in humidity and a dimensional change due to a load, as compared with a film composed of only the F layer.

Here, the metals in the present invention represent so-called single metals, metalloids, alloys, and intermetallic compounds. Specifically, for example, single metals include Mg, Al, Ti, V, Cr, Mn, Fe, and Co. Ni, Cu, Zn, Zr, Mo, Pd, Ag, Sn, Pt, Au, Pb, semimetals include C, Si, Ge, Sb, Te, etc. It may be an alloy or an intermetallic compound. As the metal-based inorganic compound, for example, oxides, nitrides, carbides, borides, sulfides, and the like of the above metals can be used. Specifically, for example, oxides such as CuO, ZnO, Al ₂ O ₃ , SiO ₂ , Fe ₂ O ₃ , Fe ₃ O ₄ , Ag ₂ O, TiO ₂ , MgO, SnO ₂ , ZrO ₂ and InO ₃ And nitrides such as Si ₄ N ₃ , TiN, ZrN, GaN, TaN, and AlN, and carbides such as TiC, WC, SiC, NbC, ZrC, and Fe ₃ C. Moreover, said metal type inorganic compound may be used individually, respectively, and of course, multiple types may be mixed and used. Among these, the metal material constituting the M layer is at least one metal selected from the group consisting of Al, Si, Cu, Zn, Ti, Ni, and Co because of dimensional stability and ease of formation of the M layer. Or an inorganic metal compound, and aluminum, aluminum oxide or a composite thereof, or silicon oxide is particularly preferable.

  As a method for forming the M layer, physical vapor deposition or chemical vapor deposition can be used. Physical vapor deposition methods include vacuum vapor deposition and sputtering, and vacuum vapor deposition is common. In particular, in order to make the crystal grain size of the metal layer small and precise, it is necessary to increase the kinetic energy of the deposited material. Therefore, electron beam evaporation or sputtering is preferable.

  The thickness of the M layer is preferably 5 to 150 nm, more preferably 10 to 120 nm, and most preferably 15 to 100 nm. By setting it in this range, the crystal grain size of the metal of the M layer can be made fine, and it is easy to satisfy the conditions such as improvement of the reinforcing effect and no adverse effect on the surface smoothness, which is preferable. When the thickness is less than the lower limit, the crystal formation of the metal of the M layer becomes incomplete, and the effect of increasing the strength is reduced, so that the effect of improving the dimensional stability of the present invention may be reduced. If the thickness is larger than the upper limit, cracks and grain boundaries are likely to occur, the surface of the magnetic recording medium becomes rough and electromagnetic conversion characteristics deteriorate, and the M layer is prone to peeling and dropping when the manufacturing process and running are repeated. , Productivity may decrease.

  In the support of the present invention, the M layer may be provided only on one side of the F layer, or may be provided on both sides. From the viewpoint of suppressing cupping and curling when a magnetic recording tape is used, both sides of the F layer are provided. It is preferable to provide an M layer. In addition, when the thickness of said preferable M layer is provided in both surfaces of F layer, it is preferable that each M layer exists in said range.

(Young's modulus)
The support of the present invention preferably has a Young's modulus in the longitudinal direction of 5 to 20 GPa and a Young's modulus in the width direction of 5 to 20 GPa. The Young's modulus in the longitudinal direction of the support is more preferably 5.5 to 18 GPa, and particularly preferably 6.0 to 15 GPa. When the Young's modulus in the longitudinal direction is less than the lower limit, it tends to be deformed in the longitudinal direction when there is a change in tension when using a magnetic recording medium, and as a result, a dimensional change in the width direction due to Poisson's ratio is likely to occur. . On the other hand, when the Young's modulus in the longitudinal direction exceeds the upper limit, it is difficult to maintain the Young's modulus in the width direction within the range, and it becomes difficult to keep the contact state with the head stable. Moreover, the more preferable Young's modulus of the width direction of a support body is 9-18 GPa, Most preferably, it is 10-16 GPa. When the Young's modulus in the width direction of the support is less than the lower limit, the contact state with the magnetic head becomes unstable, and the electromagnetic conversion characteristics are likely to deteriorate. On the other hand, when the Young's modulus in the width direction of the support exceeds the upper limit, it is difficult to achieve the preferable Young's modulus range in the longitudinal direction of the support.

<Method for producing F layer>
The method for producing the F layer in the present invention is not particularly limited, and a method known per se can be adopted. For example, when a thermoplastic resin is used in the form of a chip, it is sufficiently dried to remove moisture. The drying conditions are preferably about 3 hours at 120 ° C. for SPS, about 6 hours at 180 ° C. for PEEK, and about 6 hours at 150 ° C. for PPS.

  In this way, the dried thermoplastic resin is supplied to an extruder and melt-kneaded at a temperature not lower than the melting point of the thermoplastic resin (hereinafter referred to as Tm) and not higher than Tm + 50 ° C. For example, about 300 ° C. is preferable for SPS and PPS, and about 380 ° C. is preferable for PEEK. As the residence time at this time becomes longer, the thermal deterioration of the thermoplastic resin proceeds, so that it is preferably as short as possible in the range where no unmelted material remains, and preferably between 5 and 30 minutes. The molten thermoplastic resin is extruded from the die into a sheet. This sheet-like material is usually cooled on the surface of the cooling drum to form an unstretched sheet. The temperature of the cooling drum at this time is adjusted by the crystallinity of the thermoplastic resin to be used. For example, it is preferably about 50 to 60 ° C. for PEEK or SPS and about 30 ° C. for PPS. When cooling with this cooling drum, it is preferable to increase the adhesion between the cooling drum and the sheet-like material by static electricity or the like because the thickness unevenness of the F layer to be obtained can be easily made uniform.

  Next, the obtained unstretched sheet is preferably stretched in the film forming direction and the width direction. The stretching temperature is preferably not less than the glass transition temperature (Tg) of the thermoplastic resin and not more than Tg + 80 ° C. The stretching ratio is preferably between 2 and 5 times, although it depends on the thermoplastic resin used. More specifically, in the case of SPS, it is preferable to stretch about 3 to 4 times in the film forming direction and in the width direction at a temperature of about 110 ° C., and in the case of PEEK, about 2 to 3 times at a temperature of about 170 to 180 ° C. The film is preferably stretched to a certain degree, and in the case of PPS, it is preferably stretched by about 1.5 to 2.5 times at a temperature of about 110 to 130 ° C. The stretching in the film forming direction and the width direction may be sequential or simultaneous, or may be multi-stage stretching that extends again in the film forming direction or the width direction.

The film thus stretched is preferably further heat-set for 1 to 20 seconds at a temperature not lower than the aforementioned stretching temperature and not higher than Tm-20 ° C. More specifically, in the case of SPS and PPS, about 200 to 220 ° C is preferable, and in the case of PEEK, about 220 to 240 ° C is preferable.
Thus, the F layer used in the present invention can be produced.

(Manufacturing method of M layer)
Next, an M layer is provided on the F layer. Here, an example of the manufacturing method of the M layer using the vacuum deposition method will be given.

An F layer is set on a film traveling device installed in a vacuum deposition apparatus, and vacuum deposition is performed. It is preferable to deposit in a high vacuum of 1.00 × 10 ^{−5 to} 1.00 × 10 ⁻¹ Pa. The film is run through a cooled metal drum at 0 to 50 ° C., the deposited material is heated and evaporated, and the film is wound on one side or both sides of the film. The film running speed is preferably 10 to 200 m / min, and more preferably 50 to 150 m / min. When the traveling speed is out of the above range, it may be difficult to set the thickness of the metal layer within a preferable range, or productivity may be inferior. When providing metal layers on both sides of the F layer, it is preferable to provide two heating vapor deposition devices and a cooling drum in the same vacuum layer, and vapor deposition on both sides in one pass, but once vapor deposition on one side, After winding, it may be performed in two passes in which a metal layer is provided on the other surface again. Further, aging is preferably performed at a temperature of 20 to 50 ° C. for 1 to 3 days, and more preferably, aging is performed in an environment where the humidity is 60% or more and no condensation occurs.

[Magnetic recording medium]
According to the present invention, a magnetic recording medium having the above support of the present invention as a base film and having a magnetic layer on one side thereof is also provided. In addition, when the surface which forms a magnetic layer is a laminated film from which front and back differ in surface roughness, it is preferable that it is the surface of a flatter one.

  The magnetic recording medium is not particularly limited as long as the laminated film of the present invention is used as a base film, for example, QIC, DLT, and high-capacity type linear track type data storage tape such as S-DLT and LTO. Is mentioned. Since the dimensional change of the base film due to changes in temperature and humidity is extremely small, it becomes a magnetic recording medium suitable for high density and high capacity that hardly causes track deviation even if the track pitch is narrowed in order to ensure high capacity of the tape. .

  According to the present invention, a magnetic recording medium in which the above support of the present invention is used as a base film, a nonmagnetic layer and a magnetic layer are formed in this order on one side, and a backcoat layer is formed on the other side. Is preferred. The composition of the nonmagnetic layer is not particularly limited, but a non-magnetic layer containing a fine inorganic powder such as silica, alumina, titanium dioxide or the like in a thermosetting resin or a high energy ray curable resin is used. The thickness of the nonmagnetic layer is preferably from 0.5 to 3.0 μm, more preferably from 1.0 to 2.0 μm, particularly preferably from 1.0 to 1.5 μm because the effects of the present invention are easily achieved.

  The kind of the magnetic layer on the nonmagnetic layer is preferably a so-called coating type in which magnetic powder is coated together with a binder from the viewpoint of the runnability of the magnetic recording medium. The type of magnetic powder constituting the magnetic layer is not particularly limited, and iron oxide, chromium oxide, cobalt-coated iron oxide, and metals such as iron, cobalt, iron-cobalt, iron-cobalt-nickel, cobalt-nickel, etc. These alloys are preferably used, but metals or alloys thereof are particularly desirable rather than oxides. Further, the binder constituting the magnetic layer is not particularly limited, but a thermosetting resin system and a high energy ray curable binder are preferable, and other additives may include a dispersant, a lubricant, an antistatic agent, and the like. . For example, vinyl chloride / vinyl acetate / vinyl alcohol copolymer, polyurethane, polyisocyanate, or a mixture thereof is preferably used. The thickness of the magnetic layer is preferably in the range of 0.1 to 1.0 μm, and more preferably in the range of 0.1 to 0.5 μm because the effects of the present invention are easily achieved.

  The composition of the backcoat layer is not particularly limited, but is preferably composed of carbon black and a thermosetting resin system or a high energy ray curable binder, and in addition, a dispersant, a lubricant, and an antistatic agent. Etc. may be contained. For example, vinyl chloride / vinyl acetate / vinyl alcohol copolymer, polyurethane, polyisocyanate, or a mixture thereof is preferably used. The thickness of the back coat layer is preferably in the range of 0.1 to 1.0 μm, and more preferably in the range of 0.3 to 0.8 μm because the effects of the present invention are easily achieved.

  In the case where the magnetic recording tape of the present invention is the above-described coating type, the ratio of the thickness obtained by subtracting the thickness of the support from the thickness of the magnetic recording tape with respect to the thickness of the support is 0.2 to 0.8. It is preferable to be in the range of double, preferably 0.3 to 0.7 times, particularly 0.3 to 0.6 times. If the thickness ratio is less than the lower limit, the magnetic layer, nonmagnetic layer, and backcoat layer become thin and coating becomes difficult, and the surface properties of the base film greatly affect the surface properties of the magnetic layer and backcoat layer. However, it may cause an error or an excessive effect of suppressing the temperature expansion by the base film may appear, resulting in a track shift. When the upper limit is exceeded, the tape thickness becomes too thick, for example, the tape length to be put in the cassette becomes short and it becomes difficult to obtain a sufficient magnetic recording capacity, and the effect of suppressing the temperature expansion by the base film is sufficiently expressed. It may be difficult.

  Further, when the ferromagnetic metal thin film layer made of iron, cobalt, nickel, chromium or an alloy or oxide containing these as a main component is formed on the surface of the support of the present invention by vacuum deposition, the above-described coating type Compared to the above, a magnetic recording medium having a smaller humidity expansion coefficient can be obtained. The metal thin film layer preferably has a thickness of 100 to 300 nm. Further, a protective layer such as diamond-like carbon (DLC) and a fluorine-containing carboxylic acid-based lubricating layer may be sequentially provided on the surface of the ferromagnetic metal thin film layer as required, for purposes, and as required. Further, if necessary, a back coat layer may be provided on the other surface of the support of the present invention by a known method. By doing so, it can be used as a ferromagnetic metal thin film vapor deposition type magnetic recording medium which is excellent in electromagnetic conversion characteristics such as output in a short wavelength region, S / N, C / N, etc., and has low dropout and error rate.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the present invention, the characteristics were measured and evaluated by the following methods.

(1) Intrinsic viscosity The obtained thermoplastic resin has an intrinsic viscosity of 35 ° C. by dissolving the polymer using a mixed solvent of P-chlorophenol / 1,1,2,2-tetrachloroethane (40/60 weight ratio). Determined by measuring with.

(2) Glass transition point and melting point Glass transition point (Tg) and melting point (Tm) were measured by enclosing 10 mg of sample in an aluminum pan for measurement and heating by DSC (TA Instruments, trade name: Q100). Measurement was performed at a rate of 20 ° C./min.

(3) Number average molecular weight A gel permeation chromatography (GPC) apparatus equipped with a differential refractometer and a differential pressure viscometer as a detector, and using a calibration curve created from standard polystyrene, the number average molecular weight (Mn) is calculated. Asked. Chloroform was used as an eluent, and three Shodex 806L manufactured by Showa Denko Co., Ltd. were connected and used as a column.

(4) Melt viscosity Obtained as a result of measurement using a capillary rheometer (capillograph model 1D) manufactured by Toyo Seiki Co., Ltd. with a capillary length of 10.0 mm, a capillary diameter of 1.0 mm, and a measurement temperature of 380 ° C. The melt viscosity at 1000 sec ⁻¹ was read from the obtained Shear Rate / Viscosity curve.

(5) Young's modulus The obtained support for magnetic recording media was cut out with a sample width of 10 mm and a length of 15 cm, and a universal tensile tester (Toyo Baldwin) under the conditions of 100 mm between chucks, 10 mm / min tensile speed, and 500 mm / min chart speed. Product, product name: Tensilon). The Young's modulus was calculated from the tangent of the rising portion of the obtained load-elongation curve.

(6) Humidity expansion coefficient (αh)
The obtained support for a magnetic recording medium was separated from the center portion in the width direction toward both ends by 10 cm at intervals of 5 cm in the width direction, and 10 mm so that the measurement direction was the film forming direction and the width direction. Cut into individual pieces, set to TMA4000SA manufactured by Bruker AXS so that the length between chucks is 15 mm, and measure the length of each sample at a humidity of 20% RH and a humidity of 80% RH in a nitrogen atmosphere at 30 ° C. The humidity expansion coefficient (αh) was calculated by the equation. Note that the measurement direction is the longitudinal direction of the sample cut out, and for each measurement direction, ten measurement results were obtained, and the difference between the average value, the maximum value, and the minimum value was calculated therefrom.
αh = (L ⁸⁰ −L ²⁰ ) / (L ²⁰ × ΔH)
Here, L ²⁰ in the above formula is a sample length (mm) when 20% RH, L ⁸⁰ is a sample length (mm) when 80% RH, ΔH: 60 (= 80-20)% RH is there.

(7) Creation of data storage (magnetic tape)
With a die coater, a nonmagnetic paint and a magnetic paint having the following composition were simultaneously dried on the surface of the support for a magnetic recording medium having a length of 850 m that was slit to a width of 500 mm under a tension condition of 20 MPa. The non-magnetic layer and the magnetic layer are applied in different thicknesses so that the thicknesses are 1.2 μm and 0.1 μm, respectively, are magnetically oriented, and are dried at 120 ° C. for 30 seconds. Further, after calendering with a small test calender (steel roll / nylon roll, 5 stages) at a temperature of 70 ° C. and a linear pressure of 200 kg / cm, curing is performed at 70 ° C. for 48 hours. Next, a back coat having the following composition was applied to the opposite surface of the magnetic layer so that the thickness of the solid content was 0.5 μm, and then the temperature was 85 ° C. with a small test calender (steel / nylon roll, 5 steps). And calendering and winding at a linear pressure of 200 kg / cm. The original tape was slit into a 1/2 inch width and incorporated into an LTO case to produce a data storage cartridge having a length of 850 m.

(Composition of non-magnetic paint)
・ Non-magnetic inorganic powder (α-iron oxide: average major axis length: 0.15 μm, average needle ratio: 7, BET specific surface area: 52 m ² / g): 100 parts by weight • SREC A (made by Sekisui Chemical, vinyl chloride / Vinyl acetate copolymer): 10 parts by weight-Nipporan 2304 (polyurethane elastomer made by Nippon Polyurethane): 10 parts by weight-Coronate L (polyisocyanate made by Nippon Polyurethane): 5 parts by weight-Lecithin: 1 part by weight-Methyl ethyl ketone: 75 parts by weight Parts: methyl isobutyl ketone: 75 parts by weight toluene: 75 parts by weight carbon black (average particle size: 20 nm): 2 parts by weight lauric acid: 1.5 parts by weight (composition of magnetic paint)
・ Magnetic powder (Toda Kogyo Co., Ltd., trade name: NF30x): 100 parts by weight. ・ Sleck A (Sekisui Chemical, vinyl chloride / vinyl acetate copolymer): 10 parts by weight. : 10 parts by weight-Coronate L (polyisocyanate made from Japanese polyurethane): 5 parts by weight-Lecithin: 1 part by weight-Methyl ethyl ketone: 75 parts by weight-Methyl isobutyl ketone: 75 parts by weight-Toluene: 75 parts by weight-Carbon black (average particles Diameter: 20 nm): 2 parts by weight Lauric acid: 1.5 parts by weight (backcoat composition)
Carbon black (average particle size 20 nm): 95 parts by weight
Carbon black (average particle size 280 nm): 10 parts by weight
・ Α alumina: 0.1 parts by weight
・ Modified polyurethane: 20 parts by weight
-Modified vinyl chloride copolymer: 30 parts by weight
・ Cyclohexanone: 200 parts by weight
・ Methyl ethyl ketone: 300 parts by weight
・ Toluene: 100 parts by weight

(8) Thickness of support, F layer and M layer The thickness of the support for magnetic recording medium and the thickness of F layer is 10 layers of the support for magnetic recording medium or F layer while excluding air between layers. In accordance with C2151, the thickness is measured by a 10-sheet overlapping method using a dial gauge MDC-25S manufactured by Mitutoyo Corporation, and the thickness of the support for a magnetic recording medium per sheet is calculated. This measurement was repeated 10 times, and the average value was taken as the total thickness of the magnetic recording medium support or F layer per sheet.
On the other hand, for the thickness of the M layer, a small piece of the support is fixedly molded with an epoxy resin, and an ultrathin section (cut in parallel with the film forming direction and the thickness direction) of about 60 nm in thickness is prepared with a microtome. . The sample of the ultrathin section was observed with a transmission electron microscope, and the thickness of the M layer was determined from the boundary.

(9) Variation in dimensional stability on magnetic tape Ten pieces of the magnetic tape prepared in (7) above were extracted and left for 24 hours at a temperature of 30 ° C and humidity of 20% RH. , The width (L20) of the magnetic tape was measured in a state where a tension of 20 MPa was applied using a laser external measuring instrument (main body: 3100 type, sensor: 3060 type) manufactured by Keyence Corporation, and then the temperature was 30 ° C. and the humidity was 80 After standing for 24 hours in the state of% RH, the width (L80) of the magnetic tape was again measured in the same manner, and the dimensional change amount (ΔL: L80-L20) of each magnetic tape was determined. The difference between the maximum value and the minimum value of the obtained 10 dimensional change amounts (ΔL) is 0.7 μm or more is poor, less than 0.7 μm is 0.2 μm or more, and is less than 0.2 μm. Things were excellent.

[Example 1]
Syndiotactic polystyrene (manufactured by Idemitsu Kosan Co., Ltd., trade name: ZAREC 142ZE) is pre-dried in a gear oven at 120 ° C. for 3 hours and then supplied to an extruder and die at 295 ° C. (average residence time: 20 minutes). Then, it was extruded into a sheet form on a cooling drum having a temperature of 55 ° C. while being rotated in a molten state to obtain an unstretched film. Then, between two sets of rollers having different rotational speeds along the film forming direction, the film surface temperature is heated from above by an IR heater so that the film surface temperature becomes 110 ° C., and stretching in the longitudinal direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 3.0. Then, this uniaxially stretched film is guided to a stenter, and after preheating at 110 ° C. for 4 seconds, a stretching temperature of 120 ° C., a stretching ratio of 3.5 times, then heat setting treatment (205 ° C. for 2 seconds) and cooling, A biaxially oriented film of SPS having a thickness of 4.5 μm was obtained.
The M layer was provided by the following method on the surface (surface not in contact with the cooling drum) on which the magnetic layer of the biaxially stretched film prepared by the above method was applied. First, the obtained biaxially stretched film was set in a film traveling device installed in a vacuum deposition apparatus, and after making a high vacuum of 1.00 × 10 ⁻³ Pa, through a cooling metal drum at 20 ° C. I drove it. At this time, aluminum was heated and evaporated with an electron beam while introducing oxygen gas to form an alumina reinforced film layer (M layer: thickness 100 nm), thereby preparing a support for a magnetic recording medium.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Example 2]
A support for a magnetic recording medium was prepared in the same manner as in Example 1 except that the surface on which alumina was deposited in Example 1 was changed to a running surface (surface in contact with the cooling drum).
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Example 3]
A support for a magnetic recording medium was prepared in the same manner as in Example 1 except that the M layer was formed on both sides and oxygen gas was not introduced when forming the M layer.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Example 4]
A support for a magnetic recording medium was prepared in the same manner as in Example 1, except that the M layer was changed to both sides and the thickness of each M layer was changed as shown in Table 1.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Example 5]
PEEK (Victrex 381G) was pre-dried in a gear oven at 180 ° C. for 6 hours, and then fed to an extruder to be rotated at a temperature of 385 ° C. (average residence time: 20 minutes) from the die in a molten state at 60 ° C. An unstretched film was extruded on a cooling drum at 0 ° C. in a sheet form. Then, between two sets of rollers having different rotational speeds along the film forming direction, the film surface temperature is heated from above by an IR heater so that the film surface temperature becomes 170 ° C., and stretching in the machine direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 2.0. Then, this uniaxially stretched film is guided to a stenter, and after preheating at 140 ° C. for 4 seconds, a stretching temperature of 180 ° C., a stretching ratio of 2.5 times, followed by heat setting treatment (230 ° C. for 2 seconds) and cooling, A biaxially oriented PEEK film having a thickness of 4.5 μm was obtained. A support for a magnetic recording medium was prepared in the same manner as in Example 4 except that the thickness of the M layer was changed as shown in Table 1 on both surfaces of the film thus obtained.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Example 6]
Support for magnetic recording medium in the same manner as in Example 4 except that the vertical magnification is changed to 3.5 times, the horizontal magnification is changed to 4.0 times, and the thickness of the M layer is changed as shown in Table 1. Created the body.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Example 7]
A support for a magnetic recording medium was prepared in the same manner as in Example 6 except that the film forming the M layer was silica.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Example 8]
PPS (Polyplastics Fortron 0220A9) is pre-dried in a gear oven at 120 ° C for 3 hours and then fed into an extruder and rotated in a molten state from a die at 295 ° C (average residence time: 20 minutes). An unstretched film was extruded on a cooling drum having a temperature of 30 ° C. in a sheet shape. Then, between two sets of rollers having different rotational speeds along the film forming direction, the film surface temperature is heated from above by an IR heater so that the film surface temperature becomes 110 ° C., and stretching in the longitudinal direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 1.8 times. Then, this uniaxially stretched film is guided to a stenter, and after preheating at 110 ° C. for 4 seconds, a stretching temperature of 120 ° C., a stretching ratio of 2.5 times, and then heat setting treatment (205 ° C. for 2 seconds) and cooling, A biaxially oriented film of SPS having a thickness of 4.5 μm was obtained. M layers were formed on both sides of the film thus obtained in the same manner as in Example 6 to produce a magnetic recording medium support.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Comparative Example 1]
Polyethylene terephthalate (PET) having an intrinsic viscosity of 0.62 is dried in a gear oven in advance at 160 ° C. for 3 hours, and then supplied to an extruder and melted from a die at 280 ° C. (average residence time: 20 minutes). An unstretched film was extruded on a cooling drum having a temperature of 30 ° C. during rotation in the form of a sheet. And between two sets of rollers with different rotation speeds along the film forming direction, the film surface temperature is heated from above by an IR heater so that the film surface temperature becomes 100 ° C., and stretching in the longitudinal direction (film forming direction) A uniaxially stretched film was obtained at a magnification of 3.5. Then, this uniaxially stretched film is guided to a stenter, preheated at 105 ° C. for 4 seconds, stretched at 110 ° C., stretch ratio 4.5 times, then heat-fixed (205 ° C. for 2 seconds) and cooled, A biaxially oriented film of PET having a thickness of 4.5 μm was obtained. Then, in the same manner as in Example 1, an M layer was formed on the surface on which the magnetic layer was applied, and a magnetic recording medium support was prepared.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Comparative Example 2]
A support for a magnetic recording medium was prepared in the same manner as in Comparative Example 1 except that the surface on which the M layer was formed was changed to a running surface.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Comparative Example 3]
A support for a magnetic recording medium was prepared in the same manner as in Comparative Example 1 except that the M layer was changed to both the magnetic surface and the running surface.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Comparative Example 4]
Polyethylene-2,6-naphthalenedicarboxylate (PEN) having an intrinsic viscosity of 0.62 is pre-dried in a gear oven at 180 ° C. for 6 hours and then fed to an extruder at 280 ° C. (average residence time: 20 minutes) The sheet was extruded from a die onto a cooling drum having a temperature of 60 ° C. while rotating in a molten state to form an unstretched film. Then, between the two sets of rollers having different rotation speeds along the film forming direction, the film surface temperature is heated from above by an IR heater so that the film surface temperature becomes 140 ° C., and stretching in the machine direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 4.5 times. Then, this uniaxially stretched film is guided to a stenter, preheated at 130 ° C. for 4 seconds, then stretched at 150 ° C., stretch ratio of 5.0 times, then heat-set (205 ° C. for 2 seconds) and cooled, A biaxially oriented film of PEN having a thickness of 4.5 μm was obtained. And M layer was formed in both surfaces by the method similar to Example 5, and the support body for magnetic recording media was created.
Table 1 shows the characteristics of the obtained magnetic recording medium support.

[Comparative Example 5]
A film as shown in Table 1 was obtained in the same manner as in Comparative Example 3 except that the vertical magnification was 4.0 times and the horizontal magnification was 5.0 times.

  In Table 1, MD is the film forming direction, TD is the film width direction, the magnetic surface and the running surface are the surface and the backcoat layer on the side where the magnetic layer was formed in the preparation of the magnetic tape described above (7). Each of the surfaces on the side of the surface means the thickness of the M layer formed on each surface.

  The support of the present invention has excellent dimensional stability that could not be achieved with conventional polyethylene terephthalate, polyethylene-2,6-naphthalate or polyalkylene-6,6 ′-(alkylenedioxy) di-2-naphthoate. And can be suitably used as a base film for high-density magnetic recording media, in particular, for applications in which dimensional stability is required.

Claims (7)

A support for a magnetic recording medium in which a reinforcing film layer (M layer) made of a metal or a metal-based inorganic compound is provided on at least one surface of a thermoplastic resin film layer (F layer),
A support for a magnetic recording medium, wherein the support has a humidity expansion coefficient of 0 to 5 ppm /% RH in the longitudinal direction and the width direction.   The support for a magnetic recording medium according to claim 1, wherein the thickness of the M layer is in the range of 10 to 150 nm.   The support for a magnetic recording medium according to claim 1, wherein the thickness of the F layer is in the range of 3 to 5 μm.   The magnetic recording medium support according to claim 1, wherein the M layer is at least one metal selected from the group consisting of Al, Si, Cu, Zn, Ti, Ni, and Co or a metal-based inorganic compound.   The support for magnetic recording media according to claim 1, wherein M layers are provided on both sides of the F layer.   2. The support for a magnetic recording medium according to claim 1, wherein the thermoplastic resin is one selected from the group consisting of polyetheretherketone, syndiotactic polystyrene, and polyphenylene sulfide.   A magnetic recording medium comprising the support according to claim 1 and a magnetic layer formed on at least one surface thereof.