JP2005205824A - Polyester film roll and manufacturing method of magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film roll for a magnetic recording medium which is suitable for manufacturing a ferromagnetic metal thin film type magnetic recording medium with a high quality and excellent productivity. <P>SOLUTION: The polyester film roll is prepared by winding around a cylindrical core a polyester film which comprises a layer A and a layer B being two polyester layers, of which the surface on the layer A side has an arithmetic mean roughness Ra of 1-4 nm and the surface on the layer B side an arithmetic mean roughness Ra of 5-30 nm and which has a width of 600-1,000 mm and a winding length of 20,000-60,000 m. An air inclustion rate of the polyester film roll is 2-10% and a discrepancy in a roll end face is 2 mm or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a magnetic film suitable for producing high-quality, high-productivity ferromagnetic film-type magnetic recording media for recording digital data, such as polyester films for magnetic recording media, particularly digital video cassette tapes and data storage tapes. The present invention relates to a polyester film roll for recording media.

  The consumer digital video tape put into practical use in 1995 is obtained by providing a cobalt metal magnetic thin film on a base film having a thickness of 6 to 7 μm by vacuum deposition and coating the surface with a diamond-like carbon film. In the case of a camera-integrated video using a DV mini-cassette, the basic specification (SD specification) has a recording time of 1 hour.

  This digital video cassette (DVC) is the world's first digital video cassette for home use, and a. A small body can record a huge amount of information, b. Since the signal does not deteriorate, the image quality and sound quality will not deteriorate even after many years c. Enjoy high image quality and high sound quality because it is not affected by noise, d. It has the merit that the video does not deteriorate even if dubbing is repeated, and the market is highly evaluated.

As a polyester base film of a DVC tape, a polyester film containing fine particles having a particle size of 10 to 300 nm and having fine surface protrusions having a height of 5 to 90 nm formed by the fine particles is adhered to at least one surface of the film. A polyester film (for example, Patent Document 1) having a height of the fine surface projection higher than the height of the discontinuous film, Young's modulus Is a polyester shown in a polyethylene-2,6-naphthalate film (for example, Patent Document 2) having a thickness of 7 μm or less and a Young's modulus in the width direction of not less than 600 kg / mm ^{2 in the} longitudinal direction. Base film is used.

For these DVC tapes, the demand for cost reduction is increasing, and it is indispensable to increase tape productivity. For example, when creating a film roll using a polyester film as shown in Patent Document 1, etc., in order to improve tape productivity more than before, the product width of the polyester film roll is increased and the winding length is increased. However, in the conventional technology, the amount of air biting during winding increases by more than 10%, and it becomes difficult to eliminate the trapped air, and there is a problem that deviation occurs during winding. Yes, there was no polyester film roll having a product width of 600 mm or more and a winding length of 20000 m or more and a roll end face deviation of 2 mm or less. As a result, no further increase in the number of tape turns obtained in one process is expected, and the waiting time, which is indispensable for replacing the original film roll, cannot be reduced. was there.
Japanese Examined Patent Publication No. 6-5401 Japanese Patent Laid-Open No. 5-185507

  An object of the present invention is suitable for manufacturing a high-quality, high-productivity ferromagnetic metal thin film magnetic recording medium that records digital data, such as a digital video cassette tape and a data storage tape, and has a good winding shape. It is to provide a polyester film roll.

  That is, the present invention includes a layer A and a layer B which are two polyester layers, the arithmetic average roughness Ra of the surface on the layer A side is 1 to 4 nm, and the arithmetic average roughness Ra of the surface on the layer B side is 5 to 5. A polyester film having a thickness of 30 nm, a width of 600 to 1000 mm, and a winding length of 20000 to 60000 m is wound on a cylindrical core, and has an air bite rate of 2 to 10% and a roll end face deviation of 2 mm or less. A polyester film roll.

  The present invention is also a method for producing a magnetic recording medium, comprising using the polyester film roll of the present invention and providing a magnetic metal thin film on the surface of the polyester film on the layer A side.

  According to the present invention, a large number of DVC magnetic recording tapes can be collected with a high yield by a single vapor deposition operation, that is, the quality and productivity of the magnetic recording medium can be improved.

  The polyester film constituting the polyester film roll of the present invention comprises layer A and layer B, which are two polyester layers.

  The polyester for forming the layer A and the layer B may be any polyester that can be used as a film having molecular strength and can be used practically for magnetic recording tape. Among them, polyethylene terephthalate, polyethylene-2,6-naphthalate Is particularly preferred. It is also preferred that 80% or more of the constituent components are ethylene terephthalate or ethylene naphthalate. Further, polyethylene terephthalate or polyethylene-2,6-naphthalate may be copolymerized with each other, or may be copolymerized with other copolymer components. Examples of other copolymer components include diol components such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylylene glycol, and 1,4-cyclohexanedimethanol, adipic acid, sebacic acid, phthalic acid, and isophthalic acid. And dicarboxylic acid components such as 5-sodiumsulfoisophthalic acid, polyfunctional dicarboxylic acid components such as trimellitic acid and pyromellitic acid, and p-oxyethoxybenzoic acid. Further, polyethylene terephthalate or polyethylene-2,6-naphthalate may be mixed with each other, or may contain other resins such as polyetherimide. In addition, an alkali metal salt derivative of sulfonic acid that is non-reactive with polyester, polyalkylene glycol substantially insoluble in polyester, or the like may be mixed so as not to exceed 5% by weight.

  It is preferable that the layer A contains 0.01 to 1.0% by weight, preferably 0.02 to 0.8% by weight, of particles having an average particle diameter of 30 to 150 nm, preferably 40 to 100 nm. Thereby, surface protrusions are formed, and the durability of the magnetic layer is also improved. As the particles, silica, calcium carbonate, alumina, etc. can be used as inorganic compounds, and polyacrylic acid, polystyrene, polyvinyl alcohol, tragacanth rubber, casein, gelatin, cellulose derivatives, water-soluble polyester, polyurethane, etc. can be used as organic compounds, These blends can also be used.

  The layer B preferably contains particles having an average particle diameter of 100 to 600 nm, and more preferably 150 to 500 nm as the average particle diameter. As the particles, calcium carbonate, silica, alumina, polystyrene, or the like can be used.

  Further, another layer may be provided between the layer A and the layer B.

  Further, the layer A side of the polyester film is made of an organic compound containing 0.5 to 12% by weight, preferably 0.6 to 10% by weight of fine particles having an average particle size of 5 to 30 nm, preferably 8 to 30 nm. It is preferable to provide a coating layer. Here, the “layer A side” means that the layer A and the layer B are positioned not on the layer B side but on the layer A side in the laminated relationship. By providing the coating layer on the layer A side, it is possible to improve running durability with the magnetic head when the magnetic recording tape is formed.

  Such fine particles include, for example, polyacrylic acid, polystyrene, polyethylene, polyester, polyacrylic acid ester, polymethyl methacrylate, polyepoxy resin, polyvinyl acetate, acrylic-styrene copolymer, acrylic copolymer, and various modifications. Organic compound particles such as acrylic resins, styrene-butadiene copolymers, various modified styrene-butadiene copolymers, and inorganic particles such as silica, alumina, and calcium carbonate can be employed. In addition, it is also possible to employ those obtained by coating these fine particles as nuclei and further coated with an organic polymer. The organic polymer that forms fine particles by coating fine particle species is preferably a self-crosslinkable one having terminal groups modified with epoxy, amine, carboxylic acid, hydroxyl group or the like.

  Organic compounds used for the matrix of the coating layer include polyvinyl alcohol, tragacanth rubber, casein, gelatin, cellulose derivatives, water-soluble polyester, polyurethane, acrylic resin, acrylic-polyester resin, isophthalic acid ester resin, methacrylic acid ester resin, and the like. Polar polymers or blends thereof can be used.

  Moreover, it is preferable to provide the slippery coating layer formed by application | coating etc. in the layer B side of a polyester film. Here, the “layer B side” means that the layer B and the layer A are positioned on the layer B side, not the layer A side, in the stacked relationship between the layer B and the layer A. The slippery coating layer has a function of exhibiting slipperiness between the cooling can and being hard to be scraped, and not allowing degradation products from the polyester film to pass through.

  The slippery coating layer is preferably composed mainly of a water-soluble polymer and / or a water-dispersible polymer and a slippery agent. The slipperiness of the coating layer is improved by the slippery agent, and traveling with the cooling can and wear resistance are ensured. Moreover, blocking between films when a polyester film is wound is prevented.

  Examples of water-soluble polymers include polyvinyl alcohol, natural rubber such as tragacanth gum and gum arabic, casein, cellulose derivatives such as methylcellulose, hydroxyethylcellulose and carboxymethylcellulose, and water-soluble polyester copolymers such as polyester ether copolymers. Etc. can be used. Among these, a blend of a cellulose derivative and a water-soluble polyester copolymer is particularly preferable. The water-soluble polyester copolymer contributes to increase the adhesion between the cellulose derivative and the polyester film surface, and the cellulose derivative contributes to prevent precipitation of the polyester degradation product.

  As the water-soluble polyester copolymer, for a polyester obtained by polycondensation of a dicarboxylic acid component and a glycol component, for example, a functional acid component such as a dicarboxylic acid component having a sulfonic acid group is added to 5 mol% of the total carboxylic acid component. Water-soluble ones can be preferably employed by copolymerization as described above or by copolymerizing 2 to 70% by weight of a polyalkylene ether glycol component as a glycol component. As the dicarboxylic acid having a sulfonic acid group, 5-sulfoisophthalic acid, 2-sulfoterephthalic acid and the like, metal salts thereof, phosphonium salts and the like can be preferably used, and 5-sodium sulfoisophthalic acid is particularly preferable. As the other dicarboxylic acid component when 5-sodium sulfoisophthalic acid is copolymerized, isophthalic acid, terephthalic acid and the like are preferable, and as the glycol component, ethylene glycol, diethylene glycol and the like are preferable.

  As the water dispersible polymer, polymethyl methacrylate, polyacrylic acid ester, and the like can be used.

  Silicone and fluorine compounds can be used as the lubricant. Further, as the silicone, a polymer such as polydimethylsiloxane in which a large number of organic silicon compounds having a siloxane bond in the molecular skeleton are connected by a covalent bond can be used.

  When silicone is employed as the slippery agent, the slippery coating layer preferably further contains a silane coupling agent. The silane coupling agent contributes to preventing the silicone from being released from the lubricant layer, and further contributes to improving the adhesion between the coating layer and the polyester. Examples of the silane coupling agent include organosilicon monomers having two or more different reactive groups in the molecule. The reactive group is selected from those which bind to the side chain, terminal group and polyester of the water-soluble polymer. One of the reactive groups is a methoxy group, an ethoxy group, a silanol group, and the other reactive group is vinyl. Group, epoxy group, methacryl group, amino group, mercapto group and the like. Examples of the silane coupling agent include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β ( Aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane and the like can be applied.

  Cellulose derivative / water-soluble polyester copolymer when a water-soluble polymer blended with a cellulose derivative and a water-soluble polyester copolymer is combined with silicone and a silane coupling agent to form a slippery coating layer The weight ratio of / silicone / silane coupling agent is preferably 100 / (100 to 500) / (1 to 20) / (10 to 50).

  In order to make the slippery coating layer difficult to scrape, it is preferable that particles are not substantially present in the slippery coating layer. In the film forming process, even if particles having a particle size up to about 3 times the thickness of the slippery coating layer are contained in an amount of about 20% by weight with respect to the slippery coating layer, problems such as scraping hardly occur. The slippery coating layer may be substantially free of particles in order to prevent falling off due to scraping with the cooling can and preventing scraping with various transport rolls in the magnetic tape processing process. preferable. However, it is permissible to include particles having a particle diameter equal to or less than the thickness of the easy-slip coating layer. The particles are effective in reinforcing the slippery coating layer.

  Moreover, it is preferable that the thickness of an easy-slip coating layer shall be 1-10 nm, More preferably, it is 2-6 nm. By setting the thickness to 1 nm or more, it is possible to obtain an effect of imparting slipperiness and preventing transfer of dirt. Further, by setting the thickness to 10 nm or less, it is possible to prevent the slippery coating layer from being scraped or peeled off.

  In the polyester film constituting the polyester film roll of the present invention, it is important that the arithmetic average roughness Ra value of the surface on the layer A side is 1 to 4 nm, preferably 1.5 to 3 nm. Here, the “surface on the layer A side” means the surface of the polyester film located on the side of the layer A in the lamination relationship between the layer A and the layer B as described above, and the layer A is located on the outermost layer. In this case, the opposite side of the layer A to the laminated surface is the surface on the layer A side, and when the coating layer is provided on the layer A, the opposite side to the laminated surface of the coating layer is the surface on the layer A side. When the Ra value is less than 1 nm, a magnetic layer such as a ferromagnetic thin film formed outside the surface A becomes too smooth, for example, during recording and reproduction in a digital video tape recorder in the case of a video tape. The video head may wear the ferromagnetic thin film. On the other hand, if the Ra value exceeds 4 nm, the magnetic layer such as a ferromagnetic thin film formed outside the surface A becomes too rough, and the output characteristics of the video tape deteriorate.

  Moreover, it is important for the polyester film which comprises the polyester film roll of this invention that the Ra value of the surface by the side of layer B is 5-30 nm, Preferably it is 7-25 nm. Here, the “surface on the side of the layer B” means the surface of the polyester film located on the side of the layer B in the laminated relationship between the layer B and the layer A as described above, and the layer B is located on the outermost layer. In this case, the opposite side of the layer B to the layer B surface is the surface of the layer B side, and when the slippery coating layer is provided on the layer B, the side opposite to the layered surface of the slippery coating layer is the layer B side surface. It becomes. When the Ra value on the surface on the layer B side is less than 5 nm, the friction coefficient between the surface on the layer A side and the surface on the layer B side becomes too high to be slippery, and they are stuck to each other on the roll. A product with a good winding shape cannot be obtained, and wrinkles are likely to occur due to contact with guide rolls in various places in the tape forming process. On the other hand, when the Ra value on the surface on the layer B side exceeds 30 nm, the surface roughness on the layer B side is transferred to the magnetic thin film layer as a wavy deformation when wound as a magnetic recording medium in a roll shape. Conversion characteristics deteriorate.

  The Ra value on the surface on the layer A side and the Ra value on the surface on the layer B side are adjusted by the component, particle size, addition amount, etc. of the particles to be added to the layer A, layer B or the coating layer and the slippery coating layer. be able to.

  In the polyester film roll of the present invention, the width of the polyester film is 600 to 1000 mm, and preferably 620 to 750 mm. If it is less than 600 mm, the tape productivity decreases. If it exceeds 1000 mm, the winding shape tends to deteriorate.

  Moreover, the polyester film roll of this invention sets the winding length of a polyester film to 20000-60000m, and 25000-50000m is preferable. If it is 20000 m or less, the number of tape windings obtained by one processing is small, the labor and time required for switching increase, and tape productivity decreases. On the other hand, if it exceeds 60000 m, the winding shape tends to deteriorate.

  In the polyester film roll of the present invention, it is important that the air bit rate is 2 to 10%, preferably 2.5 to 5.0%. When the air bit rate exceeds 10%, when the polyester film roll is slit to a predetermined width and length from the polyester film roll of the film forming machine by a slitter, the roll surface layer portion where the air bite amount increases is particularly displaced. Occurs and the winding appearance deteriorates. On the other hand, if the air entrapment ratio is less than 2%, the surface on the layer A side and the surface on the layer B side are too close to each other, and the surface roughness on the surface on the layer B side is transferred to the surface on the layer A side. The surface on the A side is deformed in a wavy shape, and the electromagnetic conversion characteristics are deteriorated.

  In the polyester film roll of the present invention, it is important that the deviation of the roll end face is 2 mm or less, preferably 1 mm or less. If the roll end face deviation is larger than 2 mm, the wrinkled part of the unrolled roll from the original roll is deposited during the deposition of the magnetic metal thin film, and the wrinkled part tends to float on the vapor deposition machine cooling can and cause heat loss. It becomes.

  The polyester film roll of the present invention is preferably used as a base film for a magnetic recording medium. In particular, it is preferably used for a digital recording vapor deposition type magnetic recording tape. For example, when it is used for a digital video tape, excellent results can be obtained. Also, excellent results can be obtained when used for data storage tape applications.

  An example of the method for producing the polyester film roll of the present invention will be described.

  The raw material for layer A and the raw material for layer B are melt-coextruded and cooled and solidified on a casting drum to obtain an unstretched film sheet.

  This is uniaxially stretched in the longitudinal direction or the width direction of the process, and preferably, a coating liquid for forming a coating layer is applied to the layer A side, and a coating liquid for forming a slippery coating layer is applied to the layer B side and dried. May be. As these coating liquids, aqueous liquids in which the respective materials of the coating layer and the slippery coating layer as described above are dissolved or dispersed can be used. Next, the film is stretched and oriented in a direction orthogonal to the previous uniaxial stretching direction and heat-set.

  Biaxial stretching can be performed by the simultaneous biaxial stretching method in addition to the sequential biaxial stretching method as described above. In addition, the film may be stretched again in the longitudinal direction, the width direction, or both the longitudinal direction and the width direction before heat setting, so that the mechanical strength of the film can be increased.

  In addition, it is good for the film-forming length of a polyester film to be the grade which added the additional length of about 200 m with respect to the winding length in a polyester film roll.

The polyester film can be wound on an intermediate spool core with a film forming machine width, and the intermediate spool film can be wound on a cylindrical core while being slit with a slitter at a film width of 600 mm to 1000 mm to form a polyester film roll. . At that time, the film is wound while being pressed by the contact roll. By adjusting the slit speed, the diameter and width of the contact roll, and the pressing pressure, the amount of air biting during winding can be controlled. The air biting rate of the roll can be adjusted to the aforementioned desired amount. Further, the degree of deviation T / L between the core and the contact roll defined as described later is preferably 2.0 × 10 ⁻⁴ or less, and more preferably 1.8 × 10 ⁻⁴ or less. By doing so, the balance of the pressing pressure applied to both ends of the product being rolled up is not lost, and the deviation of the end face of the product is set to 2 mm or less, and a product roll having a good winding shape can be obtained.

In the method for producing a magnetic recording medium of the present invention, it is important to use the polyester film roll of the present invention, and a magnetic metal thin film is provided on the surface of the polyester film on the layer A side.
The magnetic metal thin film functions as a magnetic layer in the magnetic recording medium. As the magnetic metal thin film, a ferromagnetic metal thin film is particularly preferable. The material is preferably a ferromagnetic material of iron, cobalt, nickel, or an alloy thereof. The thickness of the magnetic metal thin film layer is preferably 20 to 300 nm, more preferably 80 nm or more.

  As a method for forming the magnetic metal thin film, vacuum deposition can be preferably employed.

  When the magnetic metal thin film is formed by coating, a vinyl resin, an epoxy resin, a urethane resin, or the like may be used as a binder. Further, a lubricant, an antistatic agent, a reinforcing agent and the like may be added as appropriate.

  When a magnetic metal thin film is formed by vacuum deposition, it is also preferable to coat a diamond-like carbon film having a thickness of about 5 to 15 nm on the metal thin film and further provide a lubricant layer thereon.

  Further, a back coat layer may be provided on the side opposite to the magnetic metal thin film, that is, on the layer B side. The back coat can be provided by applying and drying a solution of a binder composed of fine particles, a lubricant, and an organic polymer in an organic solvent. As such fine particles, carbon black, alumina or the like can be used, as the lubricant, silicone, a fluorine compound or the like can be used, and as the binder, polyurethane, epoxy resin or the like can be used. The thickness of the back coat layer is preferably about 0.5 to 1.5 μm.

[Definition / Measurement Method]
(1) Intrinsic viscosity (IV)
Measurement was performed at 25 ° C. using orthochlorophenol as a solvent.

(2) Arithmetic average roughness Ra value, Ten-point average roughness Rz value Measured using an atomic force microscope (scanning probe microscope). Using a desktop small probe microscope (Nanopics 1000) manufactured by Seiko Instruments Inc., the surface of the film is scanned in an atomic force microscope in the range of 5 μm square in the damping mode, and the obtained surface profile curve is JIS B0601 Ra. The Ra value is calculated from the corresponding arithmetic average roughness, and the ten-point average surface roughness corresponding to JIS B0601 Rz, that is, the average surface of the portion extracted from the roughness curved surface by the reference area is used as the reference surface, from the highest to the fifth. Rz value was calculated | required from the distance of the average value of the altitude of a mountain, and the average value of the depth of the valley bottom from the deepest. The magnification in the in-plane direction was 20,000 times, and the magnification in the height direction was about 1 million times. The measurement direction was the film width direction, and the number of measurements was 256. The unit is expressed in nm.

(3) Degree of deviation between core and contact roll (T / L)
The contact roll is brought into contact with the core of the roll before winding the slit polyester film, and one end portion in the width direction of the film to be passed is passed through each ridge line passing through the point where the core and the contact roll are in contact with each other. The amount of deviation T (mm) on the surface of the core at the other end in the width direction of the film to be passed was measured with a micro gauge as a reference position, and the ratio to the width L (mm) of the film to be passed (T / L) was defined as the degree of deviation.

(4) Air bit rate Air bit rate (%) = (1−winding diameter calculation value from winding length / actual winding diameter) × 100
As defined and measured.

(5) Roll end face deviation amount The end face of the polyester film roll was inspected, and the maximum value of the deviation amount at which the end of the film protruded from the average position of the film end face was measured with a measure to obtain the deviation amount.

(6) Productivity of magnetic recording tape Magnetic recording tape having a width of 6.35 mm and a length of 73 m (effective recording length of 71 m, for 60-minute recording) per cassette using the polyester film rolls of the examples and comparative examples. 100 cassettes were prepared in each example and comparative example.
Recorded using a commercially available camera-integrated digital video tape recorder (DVC) (Canon FV200), played back for 1 minute, counted the number of block noise mosaics, and the number of mosaics was 0 / Minute cassette was accepted.
Of the 100 inspected products, the number of acceptable products expressed as a percentage was defined as the magnetic tape yield and the magnetic tape productivity of the polyester film roll.
In extracting 100 test articles from the magnetic recording tape collected from the polyester film roll, first, 20 areas (one area of the area) are used so that the distribution of the outer layer to the inner layer is not biased with respect to the longitudinal direction of the film. The length was 73 m). Further, in each of these 20 areas, 5 samples were taken in the width direction in the sampling region of the magnetic recording tape in the width direction (the region with respect to the width direction excluding about 5 mm each of the edge portions not subjected to vapor deposition). Collected one by one.

[Example 1]
As a raw material for layer A (raw material A), a polyethylene terephthalate raw material A (inherent viscosity IV0.66) substantially free of inert particles was prepared.

  Further, polyethylene terephthalate (intrinsic viscosity 0.66) to which 0.36% by weight of aluminum silicate particles having an average particle diameter of 300 nm was added was prepared as a raw material for layer B (raw material B).

Further, an aqueous solution having the following composition and concentration was prepared as a coating liquid (coating liquid C) for forming a coating layer on the layer A side.
Layer A outside:
Methyl cellulose (methoxyl group substitution degree 1.8, molecular weight 18000)
: 0.10% by weight
Water-soluble polyester (1: 1 copolymer of 70 mol% terephthalic acid, 30 mol% 5-sodium sulfoisophthalic acid and ethylene glycol)
: 0.30% by weight
Aminoethylsilane coupling agent (3-aminopropyltrimethoxysilane)
: 0.01% by weight
Fine particles (silica having an average particle size of 18 nm (major axis / minor axis ratio 1.1, relative standard deviation 0.1))
: 0.03% by weight.

Further, an aqueous solution having the following composition and concentration was prepared as a coating liquid (coating liquid D) for forming an easy-sliding coating layer on the surface of layer B.
Methyl cellulose (methoxyl group substitution degree 1.8, molecular weight 18000)
: 0.15% by weight
Water-soluble polyester (1: 1 copolymer of 70 mol% terephthalic acid, 30 mol% 5-sodium sulfoisophthalic acid and ethylene glycol)
: 0.25% by weight
Aminoethylsilane coupling agent (3-aminopropyltrimethoxysilane)
: 0.03% by weight
Polydimethylsiloxane (dimethylpolysiloxane with a degree of polymerization of 100, two of 202 methyl groups replaced with amino groups)
: 0.01% by weight.

  Raw material A and raw material B were coextruded at a thickness ratio of 9: 1. The total discharge amount of the raw materials A and B was finely adjusted so that the total thickness of the laminated polyester film became a target value (6.3 μm) described later.

  This was cooled and solidified on a casting drum, and longitudinally stretched 3.0 times at 105 ° C. by a roll stretching method.

  Subsequently, the coating liquid C was apply | coated to the surface of A layer by the metal ring bar system with the application | coating thickness of 4.0 micrometers.

  Moreover, the coating liquid D was apply | coated to the surface of B layer by the air knife system with the application | coating thickness of 2.5 micrometers.

Thereafter, the film was stretched 4.2 times in the transverse direction at 98 ° C. with a tenter, heat-treated at 210 ° C., wound on an intermediate spool, slit into a 620 mm width with a slitter, and a film with a diameter of 45 mm and a width on a cylindrical core. The sheet was wound at a winding speed of 200 m / min while being pressed with a pressure of 420 N / m with a contact roll made of 670 mm chloroprene rubber (the arithmetic average roughness Ra of the surface was 0.6 μm). At that time, the deviation T / L of the inclination of the center line of the core and the contact roll with respect to the vertical direction was set to 1.6 × 10 ⁻⁴ .

  Thus, a polyester film roll of the present invention having a thickness of 6.3 μm, a width of 620 mm, and a winding length of 22000 m, and having an air bite rate of 4.2% and an end face deviation of 0 mm was obtained.

  Using this polyester film roll, a cobalt-oxygen thin film having a thickness of 150 nm was formed as a ferromagnetic metal thin film on the surface on the layer A side of the polyester film by vacuum deposition.

  Next, a diamond-like carbon film having a thickness of 10 nm was formed on the cobalt-oxygen thin film layer by sputtering.

  Subsequently, a back coat layer made of carbon black, polyurethane, and silicone was provided on the surface on the layer B side with a thickness of 400 nm.

  This was slit with a slitter to a width of 6.35 mm and a length of 73 m to obtain a magnetic recording tape, which was wound on a reel to obtain a DVC cassette. The productivity of magnetic recording tape was 100% yield.

[Example 2]
In the production of the polyester film roll of Example 1, the deviation T / L of the center line between the core and the contact roll with respect to the vertical direction was set to 1.8 × 10 ⁻⁴ , the winding length was set to 28000 m, and the others were carried out. In the same manner as in Example 1, a polyester film roll was obtained. The air bit rate was 3.0%, and the end face deviation was 0 mm.

  Further, in the same manner as in Example 1, a magnetic recording tape and its DVC cassette were obtained. The productivity of magnetic recording tape was 100% yield.

[Example 3]
In the production of the polyester film roll of Example 1, the deviation degree T / L of the center line of the core and the contact roll with respect to the vertical direction was set to 0.8 × 10 ⁻⁴ , the winding length was set to 47000 m, and the others were carried out. In the same manner as in Example 1, a polyester film roll was obtained. The air bit rate was 4.6%, and the deviation of the end face was 0 mm.

  Further, in the same manner as in Example 1, a magnetic recording tape and its DVC cassette were obtained. The productivity of magnetic recording tape was 100% yield.

[Example 4]
In the production of the polyester film roll of Example 1, the deviation T / L of the center line of the core and the contact roll with respect to the vertical direction was set to 1.5 × 10 ⁻⁴ , the winding length was set to 47000 m, and the others were carried out. In the same manner as in Example 1, a polyester film roll was obtained. The air biting rate was 4.7%, and the end face deviation was 0 mm.

  Further, in the same manner as in Example 1, a magnetic recording tape and its DVC cassette were obtained. The productivity of magnetic recording tape was 100% yield.

[Example 5]
In the production of the polyester film roll of Example 1, the deviation T / L of the inclination of the center line of the core and the contact roll with respect to the vertical direction is 0.4 × 10 ⁻⁴ , the slit width is 800 mm, and the winding length is A polyester film roll was obtained in the same manner as Example 1 except for 27000 m. The air bit rate was 5.0%, and the deviation of the end face was 0 mm.

  Further, in the same manner as in Example 1, a magnetic recording tape and its DVC cassette were obtained. The productivity of magnetic recording tape was 100% yield.

[Example 6]
In the production of the polyester film roll of Example 1, the deviation T / L of the center line of the core and the contact roll with respect to the vertical direction is 0.8 × 10 ⁻⁴ , the slit width is 800 mm, and the winding length is A polyester film roll was obtained in the same manner as Example 1 except for 37000 m. The air biting rate was 8.2%, and the end face deviation was 0 mm.

  Further, in the same manner as in Example 1, a magnetic recording tape and its DVC cassette were obtained. The productivity of magnetic recording tape was 100% yield.

[Comparative Example 1]
In the production of the polyester film roll of Example 1, the deviation T / L of the inclination of the center line of the core and the contact roll with respect to the vertical direction was set to 2.2 × 10 ^−4. A film roll was obtained. The air biting rate was 12.2%, and the deviation of the end face was 3.5 mm.

  Further, in the same manner as in Example 1, a magnetic recording tape and its DVC cassette were obtained. The productivity of magnetic recording tape was 60% yield.

[Comparative Example 2]
In the production of the polyester film roll of Example 1, the deviation T / L of the center line of the core and the contact roll with respect to the vertical direction was set to 2.4 × 10 ⁻⁴ , the winding length was set to 28000 m, and the others were carried out. In the same manner as in Example 1, a polyester film roll was obtained. The air biting rate was 13.0%, and the deviation of the end face was 5.0 mm.

  Further, in the same manner as in Example 1, a magnetic recording tape and its DVC cassette were obtained. The productivity of magnetic recording tape was 60% yield.

[Comparative Example 3]
In the production of the polyester film roll of Example 1, the deviation T / L of the center line of the core and the contact roll with respect to the vertical direction is set to 3.0 × 10 ⁻⁴ , the winding length is set to 47000 m, and the others are carried out. In the same manner as in Example 1, a polyester film roll was obtained. The air biting rate was 15.5%, and the deviation of the end face was 150.1 mm.

  Further, an attempt was made to produce a magnetic recording tape in the same manner as in Example 1, but vacuum deposition was impossible, and the magnetic recording tape could not be produced.

[Comparative Example 4]
In the production of the polyester film roll of Example 1, the deviation T / L of the inclination of the core and the contact roll with respect to the vertical direction is 2.5 × 10 ⁻⁴ , the winding length is 47000 m, and the others are the same as in Example 1. In the same manner, a polyester film roll was obtained. The air biting rate was 17.2%, and the end face deviation was 125.5 mm.

  Further, an attempt was made to produce a magnetic recording tape in the same manner as in Example 1. However, vacuum deposition was impossible, and the magnetic recording tape could not be produced.

[Comparative Example 5]
In the production of the polyester film roll of Example 1, the deviation T / L of the inclination of the core and the contact roll with respect to the vertical direction is 2.3 × 10 ⁻⁴ , the slit width is 800 mm, the winding length is 27000 m, In the same manner as in Example 1, a polyester film roll was obtained. The air biting rate was 11.1%, and the deviation of the end face was 53.2 mm.

  Further, an attempt was made to produce a magnetic recording tape in the same manner as in Example 1. However, vacuum deposition was impossible, and the magnetic recording tape could not be produced.

[Comparative Example 6]
In the production of the polyester film roll of Example 1, the degree T / L of the inclination of the core and the contact roll with respect to the vertical direction is 0.8 × 10 ⁻⁴ , the pressing pressure of the contact roll is 350 N / m, and the winding length A polyester film roll was obtained in the same manner as in Example 1 except that the thickness was 47000 m. The air biting rate was 12.1%, and the end face deviation was 1.2 mm.

  Further, in the same manner as in Example 1, a magnetic recording tape and its DVC cassette were obtained. The productivity of magnetic recording tape was 50% yield.

[Comparative Example 7]
In the production of the polyester film roll of Example 1, the deviation T / L of the inclination of the center line of the core and the contact roll with respect to the vertical direction is set to 0.4 × 10 ⁻⁴ ,
A polyester film roll was obtained in the same manner as in Example 1 except that the slit speed was 100 m / min, the pressing pressure of the contact roll was 500 N / m, and the winding length was 47000 m. The air biting rate was 1.1%, and the deviation of the end face was 0 mm.

  Further, in the same manner as in Example 1, a magnetic recording tape and its DVC cassette were obtained. Dropout was particularly remarkable at a portion from 32900 m to 47000 m starting from the outer layer end of the film roll, and the productivity of the magnetic recording tape was 30%.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for manufacturing a magnetic recording tape, particularly for manufacturing a digital video tape or a data storage tape provided with a magnetic recording layer by vacuum deposition.

Claims (6)

Including layer A and layer B, which are two polyester layers, the arithmetic average roughness Ra of the surface on the layer A side is 1 to 4 nm, the arithmetic average roughness Ra of the surface on the layer B side is 5 to 30 nm, and the width is 600 A polyester film roll characterized in that a polyester film having a thickness of ˜1000 mm and a winding length of 20000 to 60000 m is wound on a cylindrical core, the air bit rate is 2 to 10%, and the deviation of the roll end face is 2 mm or less. . The polyester film roll according to claim 1, wherein the polyester is polyethylene terephthalate and / or polyethylene-2,6-naphthalate. The polyester film roll according to claim 1 or 2, wherein the polyester film is for a magnetic recording medium. The polyester film roll according to claim 3, wherein the polyester film is for a digital recording vapor deposition type magnetic recording tape. A method for producing a magnetic recording medium, comprising using the polyester film roll according to any one of claims 1 to 4 and providing a magnetic metal thin film on the surface of the polyester film on the layer A side. 6. The method of manufacturing a magnetic recording medium according to claim 5, wherein the magnetic metal thin film is a ferromagnetic metal thin film.