JP2006281672A - Heat-treating method of film and film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-treating method of a film capable of enhancing a quality and a yield by preventing generation of a buckling wrinkle due to shrinkage in a heat treatment and transfer of unevenness of overlapping surfaces, and to provide a film. <P>SOLUTION: In the heat-treating method of the film F of heat-treating the band-like flexible film F in the state that it is wound around a winding core, the winding core S is made of CFRP and has an outer diameter of not less than 400 mmϕ to not more than 600 mmϕ. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a film heat treatment method and a film, and more particularly to a film heat treatment method and a film wound on a core and heat-treated in a roll state.

  In general, a magnetic tape is manufactured by a process of [application] → [calendar] → [heat treatment] → [cutting]. Here, in the heat treatment process performed after the calendering process, the calendered base film is wound around a winding core to form a roll, and the heat treatment is performed by leaving the roll in an environmental atmosphere at a predetermined temperature for a predetermined time. Is called.

  However, when the base film is heat-treated in the roll state as described above, there is a problem that buckling wrinkles due to shrinkage and transfer of unevenness on the overlapping surface occur, leading to deterioration in quality and yield. In particular, in the case of a magnetic tape, the surface of the magnetic layer is pressed against a rough backcoat layer and deformed (back surface image), the surface roughness (Ra) increases, and dropout is likely to occur. There's a problem.

  Therefore, in Patent Document 1, it is proposed to define the cumulative number of turns according to the length of the base film and the like in order to prevent the base film wound around the core from being stretched or buckled.

Patent Document 2 proposes that a base film is wound around a core made of a two-layer structure made of glass fiber mixed with carbon on the outer side and made of carbon fiber on the inner side, and heat-treated.
JP 2000-285445 A JP-A-6-295436

  However, as the recording density is increased, the surface of the magnetic layer is required to have high smoothness, and the conventional heat treatment method has a drawback that sufficient smoothness that satisfies the product requirements cannot be obtained. . In particular, a product having a recording capacity of 100 GB or more has a drawback that if the surface of the magnetic layer is not sufficiently smooth, a spacing loss with the head occurs due to unevenness on the surface of the magnetic layer, leading to an increase in dropout.

  The present invention has been made in view of such circumstances, a film heat treatment method capable of preventing the buckling wrinkles due to shrinkage caused by the heat treatment and the transfer of the unevenness of the overlapping surface, and improving the quality and yield, and The object is to provide a film.

  In order to achieve the above object, the invention according to claim 1 is a film heat treatment method in which a heat treatment is performed in a state where a belt-like flexible film is wound around a core, and the material of the core is CFRP. The outer diameter is 400 mm or more and 600 mm or less.

  According to the first aspect of the present invention, the core material for winding the film to be heat-treated is made of CFRP (Carbon Fiber Reinforced Plastics), and the outer diameter is 400 mm or more and 600 mm or less. Thereby, it is possible to prevent buckling wrinkles due to shrinkage generated by heat treatment and transfer of unevenness on the overlapping surface, and it is possible to improve quality and yield.

  In order to achieve the above object, the invention described in claim 2 is characterized in that, in the invention described in claim 1, the film is a film having a magnetic layer coated on the surface thereof.

  According to the second aspect of the present invention, it is possible to heat-treat the film having the magnetic layer applied and formed on the surface thereof without causing buckling wrinkles or back surface reflection.

  The invention described in claim 3 is characterized by being heat treated by the heat treatment method according to claim 1 or 2 in order to achieve the object.

  According to invention of Claim 3, a high quality film can be obtained by heat-processing by the method of Claim 1 or 2.

  According to the film heat treatment method and film of the present invention, it is possible to prevent buckling wrinkles due to shrinkage caused by the heat treatment and transfer of the unevenness of the overlapping surface, thereby improving quality and yield.

  Hereinafter, the best mode for carrying out a film heat treatment method and film according to the present invention will be described with reference to the accompanying drawings. In the present embodiment, a case where the heat treatment method according to the present invention is used in a magnetic tape manufacturing process will be described as an example.

  In general, a magnetic tape is manufactured by a process of [application] → [calendar] → [heat treatment] → [slit].

  In the coating step, a magnetic layer is applied on one side and a back coat layer is formed on the other side of the strip-like flexible base film fed from the raw roll. The base film on which the magnetic layer and the back coat layer are formed is wound around a core and formed into a roll shape.

  In the calendar process, as shown in FIG. 1, the base film F in a roll state after application is rewound and sent to the calendar unit 10, the surface is smoothed by the calendar unit 10, and wound around the core S. As shown in FIG. 1, a plurality of calendar rollers C are arranged in the calendar portion 10 so as to be in contact with each other, and the base film F is guided by the guide rollers G between the plurality of calendar rollers C. In the running process, it is nipped at the nip between the calender rollers, heated and pressurized, and the surface is smoothed. And it is wound up by the core S and formed in roll shape.

  In the heat treatment step, as shown in FIG. 2, the base film F in a roll state after the calendar process is placed in a temperature-controlled room 20 at a predetermined temperature (50 ° C. or higher) while being in a roll state, and left for a predetermined time to perform heat treatment. .

  In the slitting process, the base film F in a roll state after the heat treatment is rewound, sent out to the slit portion, cut into a plurality of magnetic tapes, and wound on a core.

  Now, as described above, the magnetic tape is manufactured in the process of [application] → [calendar] → [heat treatment] → [slit], and in the heat treatment process, the base film is heat treated in a roll state.

  However, when the base film is heat-treated in a roll state in this way, there is a problem that buckling wrinkles due to shrinkage and back surface copy occur, and the quality and yield of the magnetic tape are lowered. In particular, in the case of a magnetic tape, there is a problem that if the surface roughness (Ra) increases due to the back surface projection, the dropout increases.

  Therefore, in the present embodiment, the base film is heat-treated by the following method. That is, the base film is wound around a core with a material of CFRP and an outer diameter D of φ400 mm or more and φ600 mm or less, formed into a roll shape, and subjected to heat treatment. Thereby, buckling wrinkles and back surface reflection can be prevented, and the quality and yield of the magnetic tape can be improved.

  That is, by using CFRP as the material of the core, thermal expansion and contraction of the core during heat treatment can be suppressed, and stress applied to the base film can be reduced. Thereby, when a magnetic tape is manufactured, the linearity of the tape is improved and the occurrence of a tracking error can be prevented. In addition, it is possible to reduce the heat shrinkage rate, to prevent the occurrence of buckling wrinkles of the base film, and to improve the quality and yield of the magnetic tape.

  Further, when the outer diameter D of the core is smaller than φ400 mm, the surface pressure on the core side is increased, and the back surface is liable to occur. When the outer diameter is larger than φ600 mm, the accompanying air increases at the time of winding, It has been confirmed by the inventor of the present application that buckling wrinkles are likely to occur. Therefore, by setting the outer diameter D of the winding core to φ400 or more and φ600 mm or less, it is possible to suppress the occurrence of back surface projection and buckling wrinkles, and to improve the quality and yield of the magnetic tape.

  The width and structure of the core are not particularly limited. FIG. 3 is a diagram showing an example of the configuration of the winding core S. As shown in FIG. As shown in the figure, the winding core S has a cylindrical main body 1, and shaft support portions 2 are provided at both ends thereof. The shaft support portion 2 includes a disc-shaped closing member 3 that closes both ends of the main body portion 1 and a support shaft 4 provided at the center of the closing member 3. The support shaft 4 is the center of the closing member 3. The closing member 3 is provided so as to be fitted into an opening 3 a formed in the portion. In addition, when it is set as this structure, in order to suppress a thermal deformation, it is preferable that both the main-body part 1 and the shaft support part 2 are made into CFRP.

  In addition, the winding core may have a configuration in which reinforcement such as a rib is provided inside, or the cylindrical portion may have a double structure. Further, the outer periphery may be coated with another material (however, the coating thickness is preferably within 2 mm).

  In the present embodiment, the base film is heat-treated at 50 ° C. or higher in the heat treatment step, but the temperature and time of the heat treatment are not particularly limited. The temperature of the heat treatment may be constant or may be changed gradually or stepwise.

  In the present embodiment, the case where the present invention is applied to the magnetic tape manufacturing process has been described as an example. However, the application of the present invention is not limited to this, and heat treatment is performed on other film-like products. The same applies to the case.

  Further, in the present embodiment, the case where the magnetic tape is manufactured in the process of [coating] → [calendar] → [heat treatment] → [slit] has been described as an example, but the manufacturing process of the magnetic tape to which the present invention can be applied. However, the present invention is not limited to this. For example, the steps of [Coating] → <Heat treatment> → [Calendar] → [Heat treatment] → [Slit] → <Surface treatment / heat treatment / servo light> → [Enrollment] (in parentheses are performed as necessary) The same applies to the case of manufacturing in the step).

  Moreover, when using this invention in the manufacturing process of a magnetic tape, it does not specifically limit about the material, width | variety, and length of a base film, A polyethylene terephthalate (PET), a polyethylene naphthalate (PEN), an aramid, etc. The present invention can be used for heat treatment of various types of base films.

  When the present invention is used in the magnetic tape manufacturing process, the field of use of the manufactured magnetic tape is not particularly limited. For example, the present invention is used in the magnetic tape manufacturing process used for backup of computer data. By doing so, a remarkable effect can be obtained.

  Hereinafter, a magnetic tape used for backup of computer data will be described. In this case, the magnetic tape basically means a magnetic film having a magnetic layer on one side of the base film and a back coat layer on the other side. For example, a nonmagnetic layer is further provided between the base film and the magnetic layer. It may be a magnetic tape having a configuration. Further, both surfaces may be magnetic layers.

  As the base film, those conventionally used as a base film material for magnetic tape can be used, and a non-magnetic one is particularly preferable. Examples of these are polyesters (eg, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), mixtures of polyethylene terephthalate and polyethylene naphthalate, polymers containing an ethylene terephthalate component and an ethylene naphthalate component), polyolefins (Eg, polypropylene), cellulose derivatives (eg, cellulose diacetate, cellulose triacetate), polycarbonate, polyamide (especially aromatic polyamide, aramid), polyimide (especially wholly aromatic polyimide), and other synthetic resin films. . Among these, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), aromatic polyamide and aramid are preferable.

  The thickness of the base film is not particularly limited, but is preferably in the range of 2 to 8 μm (more preferably 3 to 8 μm, particularly preferably 3 to 7 μm).

  The magnetic layer is basically made of a ferromagnetic powder and a binder. The magnetic layer usually further contains a lubricant, carbon black as a conductive powder, and an abrasive.

Examples of the ferromagnetic powder include γ-Fe ₂ O ₃ , Fe ₃ O ₄ , FeOx (x = 1.33 to 1.5), CrO ₂ , Co-containing γ-Fe ₂ O ₃ , and Co-containing FeOx (x = 1.33-1.5), ferromagnetic metal powder and plate-shaped hexagonal ferrite powder. In the present invention, it is preferable to use a ferromagnetic metal powder or a plate-shaped hexagonal ferrite powder as the ferromagnetic powder. Particularly preferred is a ferromagnetic metal powder.

The ferromagnetic metal powder has a specific surface area of preferably 30 to 70 m ² / g, and the crystallite size determined by X-ray diffraction method is 50 to 300A. If the specific surface area is too small, it will not be possible to sufficiently cope with high density recording, and if it is too large, it will not be possible to disperse sufficiently, so that it will not be possible to form a smooth magnetic layer, and thus it will not be able to cope with high density recording. The ferromagnetic metal powder is required to contain at least Fe, and specifically, a simple metal or an alloy mainly composed of Fe, Fe—Co, Fe—Ni, Fe—Zn—Ni, or Fe—Ni—Co. It is. As for the magnetic properties of these ferromagnetic metal powders, the saturation magnetization (σs) is 110 emu / g or more, preferably 120 emu / g or more and 170 emu / g or less in order to achieve a high recording density. The coercive force (Hc) is in the range of 800 to 3000 oersted (Oe) (preferably 1500 to 2500 Oe). And the long axis length (namely, average particle diameter) of the powder calculated | required with a transmission electron microscope is 0.5 micrometer or less, Preferably, it is 0.01-0.3 micrometer, and an axial ratio (long axis length / short axis length, The needle ratio) is 5 or more and 20 or less, preferably 5-15. In order to further improve the characteristics, non-metals such as B, C, Al, Si and P, or salts and oxides thereof may be added during the composition. Usually, an oxide layer is formed on the particle surface of the metal powder in order to stabilize it chemically.

The plate-shaped hexagonal ferrite powder has a specific surface area of 25 to 65 m ² / g, a plate ratio (plate diameter / plate thickness) of 2 to 15, and a plate diameter of 0.02 to 1.0 μm. is there. The plate-shaped hexagonal ferrite powder has the same reason as the ferromagnetic metal powder, so that high density recording becomes difficult even if the particle size is too large or too small. The plate-shaped hexagonal ferrite is a ferromagnetic material having a flat plate shape and an easy axis of magnetization in a direction perpendicular to the flat plate surface, specifically, barium ferrite, strontium ferrite, lead ferrite, calcium ferrite, and the like. The cobalt substitution product of these can be mentioned. Of these, cobalt substitutes of barium ferrite and cobalt substitutes of strontium ferrite are particularly preferable. To the plate-shaped hexagonal ferrite used in the present invention, elements such as In, Zn, Ge, Nb, and V may be added as necessary to improve the characteristics. Further, regarding the magnetic properties of these plate-shaped hexagonal ferrite powders, in order to achieve a high recording density, the particle size as described above is required and at the same time, the saturation magnetization (σs) is preferably at least 50 emu / g or more. Is 53 emu / g or more. The coercive force is in the range of 700 to 2000 Oersted (Oe), and preferably in the range of 900 to 1600 Oe.

The water content of the ferromagnetic powder is preferably 0.01 to 2% by weight. It is preferable to optimize the water content depending on the type of the binder. The pH of the ferromagnetic powder is preferably optimized depending on the combination with the binder used, and the pH is usually in the range of 4 to 12, preferably in the range of 5 to 10. The ferromagnetic powder may be subjected to surface treatment with Al, Si, P, or an oxide thereof as required. The amount used in the surface treatment is usually 0.1 to 10% by weight with respect to the ferromagnetic powder. By performing the surface treatment, adsorption of a lubricant such as a fatty acid can be suppressed to 100 mg / m ² or less. The ferromagnetic powder may contain soluble inorganic ions such as Na, Ca, Fe, Ni, and Sr. However, if the content is 5000 ppm or less, the properties are not affected.

  The lubricant is added to ooze out on the surface of the magnetic layer, thereby relaxing the friction between the magnetic layer surface and the magnetic head, the guide pole of the drive and the cylinder, and smoothly maintaining the sliding contact state. Examples of the lubricant include fatty acids or fatty acid esters. Examples of fatty acids include acetic acid, propionic acid, octanoic acid, 2-ethylhexanoic acid, lauric acid, myristic acid, stearic acid, palmitic acid, behenic acid, arachic acid, oleic acid, linoleic acid, linolenic acid, elaidic acid, And aliphatic carboxylic acids such as palmitoleic acid or mixtures thereof.

  Examples of fatty acid esters include butyl stearate, sec-butyl stearate, isopropyl stearate, butyl oleate, amyl stearate, 3-methylbutyl stearate, 2-ethylhexyl stearate, 2-hexyldecyl stearate, Acylation of butyl palmitate, 2-ethylhexyl myristate, butyl stearate and butyl palmitate, oleyl oleate, butoxyethyl stearate, 2-butoxy-1-propyl stearate, dipropylene glycol monobutyl ether with stearic acid , Diethylene glycol dipalmitate, hexamethylenediol acylated with myristic acid to give a diol, and various ester compounds such as glycerin oleate Can. These can be used alone or in combination. The normal content of the lubricant is in the range of 0.2 to 20 parts by weight (preferably 0.5 to 10 parts by weight) with respect to 100 parts by weight of the ferromagnetic powder of the magnetic layer.

Carbon black is added for various purposes such as reducing the surface electrical resistance (Rs) of the magnetic layer, reducing the dynamic friction coefficient (μK value), improving running durability, and ensuring the smooth surface properties of the magnetic layer. The Carbon black preferably has an average particle size in the range of 3 to 350 nm (more preferably 10 to 300 nm). The specific surface area is preferably 5 to 500 m ² / g (more preferably 50 to 300 m ² / g). The DBP oil absorption is preferably in the range of 10 to 1000 mL / 100 g (more preferably 50 to 300 mL / 100 g). The pH is preferably 2 to 10, the water content is preferably 0.1 to 10%, and the tap density is preferably 0.1 to 1 g / cc.

  Carbon black obtained by various manufacturing methods can be used. Examples of carbon black that can be used include furnace black, thermal black, acetylene black, channel black, and lamp black. Specific examples of carbon black products include BLACKPEARLS 2000, 1300, 1000, 900, 800, 700, VULCANXC-72 (above, manufactured by Cabot Corporation), # 35, # 50, # 55, # 60 and # 80. (Made by Asahi Carbon Co., Ltd.), # 3950B, # 3750B, # 3250B, # 2400B, # 2300B, # 1000, # 900, # 40, # 30, and # 10B (Mitsubishi Chemical Corporation )), CONDUCTEXSC, RAVEN150, 50, 40, 15 (above, Columbia Carbon Co., Ltd.), Ketjen Black EC, Ketjen Black ECDJ-500 and Ketjen Black ECDJ-600 (above, Lion Azo Co., Ltd.) ). The usual addition amount of carbon black is 0.1 to 30 parts by weight, preferably 0.2 to 15 parts by weight with respect to 100 parts by weight of the ferromagnetic powder.

Examples of the abrasive include fused alumina, silicon carbide, chromium oxide (Cr ₂ O ₃ ), corundum, artificial corundum, diamond, artificial diamond, garnet, and emery (main components: corundum and magnetite). These abrasives preferably have a Mohs hardness of 5 or more (preferably 6 or more) and an average particle size of 0.05 to 1 μm (more preferably 0.2 to 0.8 μm). . The addition amount of the abrasive is usually in the range of 3 to 25 parts by weight (preferably 3 to 20 parts by weight) with respect to 100 parts by weight of the ferromagnetic powder.

  Examples of the binder for the magnetic layer include thermoplastic resins, thermosetting resins, reactive resins, and mixtures thereof. Examples of thermoplastic resins include vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylic ester, vinylidene chloride, acrylonitrile, methacrylic acid, methacrylic ester, styrene, butadiene, ethylene, vinyl butyral, vinyl A polymer or a copolymer containing acetal and vinyl ether as structural units can be given. Examples of the copolymer include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylate ester-acrylonitrile copolymer, acrylate ester-vinylidene chloride copolymer. Polymer, Acrylate ester-Styrene copolymer, Methacrylate ester-Acrylonitrile copolymer, Methacrylate ester-Vinylidene chloride copolymer, Methacrylate ester-Styrene copolymer, Vinylidene chloride-Acrylonitrile copolymer , Butadiene-acrylonitrile copolymer, styrene-butadiene copolymer, and chlorovinyl ether-acrylic ester copolymer.

  In addition to the above, polyamide resins, fiber-based resins (cellulose acetate butyrate, cellulose diacetate, cellulose propionate, nitrocellulose, etc.), polyvinyl fluoride, polyester resins, polyurethane resins, and various rubber resins are also used. be able to.

  Examples of thermosetting resins or reactive resins include phenolic resins, epoxy resins, polyurethane curable resins, urea resins, melamine resins, alkyd resins, acrylic reactive resins, formaldehyde resins, silicone resins, epoxy-polyamide resins, Mention may be made of a mixture of polyester resin and polyisocyanate prepolymer, a mixture of polyester polyol and polyisocyanate, and a mixture of polyurethane and polyisocyanate.

  Examples of the polyisocyanate include tolylene diisocyanate, 4-4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthylene-1,5-diisocyanate, o-toluidine diisocyanate, isophorone diisocyanate, and triphenylmethane triisocyanate. Mention may be made of isocyanates, products of these isocyanates with polyalcohols, and polyisocyanates produced by condensation of isocyanates.

  As the polyurethane resin, known resins having structures such as polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, polyester polycarbonate polyurethane, and polycaprolactone polyurethane can be used.

In the present invention, the binder of the magnetic layer is vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, and A combination of at least one resin selected from nitrocellulose and a polyurethane resin, or a combination of these with a polyisocyanate is preferable.

As the binder, as necessary to obtain the durability of the layer obtained more excellent _{dispersibility, -COOM, -SO 3 M, -OSO} 3 M, -P = O (OM) 2, -O _{-P = O (OM) 2 (} M represents a hydrogen atom or an alkali metal salt,.), - OH, -NR 2, -N + R 3 (R is a hydrocarbon group.), an epoxy group, - It is preferable to use at least one polar group selected from SH, —CN and the like by copolymerization or addition reaction. Such polar groups are preferably introduced into the binder in an amount of 10 ^-1 to 10 ^-8 mol / g (more preferably 10 ^-2 to 10 ^-6 mol / g).

  The binder for the magnetic layer is usually used in the range of 5 to 50 parts by weight (preferably 10 to 30 parts by weight) with respect to 100 parts by weight of the ferromagnetic powder. When a combination of vinyl chloride resin, polyurethane resin, and polyisocyanate is used as a binder in the magnetic layer, the vinyl chloride resin is 5 to 70% by weight and the polyurethane resin is 2 to 50% by weight in the total binder. % And polyisocyanates are preferably used in amounts ranging from 2 to 50% by weight.

  A dispersing agent can be added to the coating solution for forming the magnetic layer of the magnetic tape in order to favorably disperse the magnetic powder in the binder. Further, if necessary, conductive particles (antistatic agent) other than plasticizer, carbon black, antifungal agent and the like can be added. Examples of the dispersant include 12 to 18 carbon atoms such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, stearic acid, and the like. A fatty acid (RCOOH, R is an alkyl group having 11 to 17 carbon atoms, or an alkenyl group), a metal soap composed of an alkali metal or an alkaline earth metal of the fatty acid, a compound containing fluorine of the fatty acid ester, Fatty acid amide, polyalkylene oxide alkyl phosphate ester, lecithin, trialkyl polyolefinoxy quaternary ammonium salt (alkyl is 1 to 5 carbon atoms, olefin is ethylene, propylene, etc.), sulfate, copper phthalocyanine, etc. Can be used. These may be used alone or in combination. The dispersant is usually added in the range of 0.5 to 20 parts by weight with respect to 100 parts by weight of the binder of the magnetic layer.

  Next, the back coat layer will be described. The backcoat layer is preferably formed from carbon black and a binder. Moreover, it is preferable that an inorganic powder or a lubricant is further added.

  It is preferable to use a combination of two types of carbon black having different average particle sizes. In this case, it is preferable to use a combination of fine particle carbon black having an average particle size of 10 to 20 nm and coarse particle carbon black having an average particle size of 230 to 300 nm. In general, by adding fine carbon black as described above, the surface electrical resistance of the backcoat layer can be set low, and the light transmittance can also be set low. Some magnetic recording devices utilize the light transmittance of the tape and are used for the operation signal. In such a case, the addition of particulate carbon black is particularly effective. In addition, particulate carbon black is generally excellent in retention of liquid lubricants, and contributes to reduction of the friction coefficient when used in combination with lubricants. On the other hand, the coarse particulate carbon black having a particle size of 230 to 300 nm has a function as a solid lubricant, and forms fine protrusions on the surface of the back layer, reducing the contact area, and reducing the friction coefficient. Contributes to reduction.

Specific products of the particulate carbon black include the following. RAVEN2000B (18 nm), RAVEN1500B (17 nm) (above, manufactured by Columbia Carbon Co., Ltd.), BP800 (17 nm) (manufactured by Cabot), PRINTEX90 (14 nm), PRINTEX95 (15 nm), PRINTEX85 (16 nm),
PRINTEX75 (17 nm) (above, manufactured by Degussa), # 3950 (16 nm) (manufactured by Mitsubishi Chemical Corporation). Examples of specific products of coarse particulate carbon black include thermal black (270 nm) (manufactured by Kerncarb) and Ravenmtp (275 nm) (manufactured by Columbia Carbon).

  When two types of backcoat layers having different average particle sizes are used, the content ratio (weight ratio) of fine particle carbon black of 10 to 20 nm and coarse particle carbon black of 230 to 300 nm is the former: latter = It is preferably in the range of 98: 2 to 75:25, more preferably in the range of 95: 5 to 85:15. The content of carbon black (the total amount thereof) in the back coat layer is usually in the range of 30 to 110 parts by weight, preferably in the range of 50 to 90 parts by weight with respect to 100 parts by weight of the binder.

  It is preferable to use two types of inorganic powders having different hardnesses. Specifically, it is preferable to use a soft inorganic powder having a Mohs hardness of 3 to 4.5 and a hard inorganic powder having a Mohs hardness of 5 to 9. By adding a soft inorganic powder having a Mohs hardness of 3 to 4.5, the friction coefficient can be stabilized by repeated running. Moreover, when the hardness is within this range, the sliding guide pole is not scraped. The average particle size of the soft inorganic powder is preferably in the range of 30 to 50 nm. Examples of the soft inorganic powder having a Mohs hardness of 3 to 4.5 include calcium sulfate, calcium carbonate, calcium silicate, barium sulfate, magnesium carbonate, zinc carbonate, and zinc oxide. These can be used alone or in combination of two or more. Among these, calcium carbonate is particularly preferable. The content of the soft inorganic powder in the backcoat layer is preferably in the range of 10 to 140 parts by weight, more preferably in the range of 35 to 100 parts by weight with respect to 100 parts by weight of the carbon black.

  By adding a hard inorganic powder having a Mohs hardness of 5 to 9, the strength of the backcoat layer is enhanced and the running durability is improved. When this is used together with carbon black, there is little deterioration even with repeated sliding, and a strong backcoat layer is obtained. In addition, the addition of the inorganic powder provides an appropriate polishing force and reduces the adhesion of shavings to the tape guide pole and the like. The hard inorganic powder preferably has an average particle size in the range of 80 to 250 nm (more preferably, 100 to 210 nm).

Examples of the hard inorganic powder having a Mohs hardness of 5 to 9 include α-iron oxide, α-alumina, and chromium oxide (Cr ₂ O ₃ ). These powders may be used alone or in combination. Among these, α-iron oxide or α-alumina is preferable. The content of the hard inorganic powder is usually in the range of 3 to 30 parts by weight, preferably in the range of 3 to 20 parts by weight with respect to 100 parts by weight of the carbon black.

  The back coat layer can contain a lubricant. The lubricant can be appropriately selected from the lubricants described in the magnetic layer. In the backcoat layer, the lubricant is usually added in the range of 1 to 5 parts by weight with respect to 100 parts by weight of the binder. Moreover, the dispersing agent described in the magnetic layer can also be added to the backcoat layer. The amount of the dispersant added can be the same as the amount added to the magnetic layer.

  As the binder for the backcoat layer, the binder described in the magnetic layer can be used. Binders that can be used include nitrocellulose resins, polyurethane resins, polyester resins, and polyisocyanates as curing agents. The binder of the backcoat layer is usually 5 to 250 parts by weight (preferably 10 to 200 parts by weight) with respect to 100 parts by weight of carbon black.

  As described above, the magnetic tape of the present invention may have a configuration in which a nonmagnetic layer is provided between the base film and the magnetic layer. That is, a magnetic tape having a nonmagnetic layer and a magnetic layer in this order on one surface of the base film and a backcoat layer on the other surface may be used.

  The nonmagnetic layer is a substantially nonmagnetic layer containing a nonmagnetic powder and a binder. This non-magnetic layer needs to be substantially non-magnetic so as not to affect the electromagnetic conversion characteristics of the magnetic layer on the non-magnetic layer, but is small enough not to affect the electromagnetic conversion characteristics of the magnetic layer. Even if the magnetic powder is contained, there is no particular problem. In addition, the nonmagnetic layer usually contains a lubricant in addition to these components.

  Examples of the nonmagnetic powder used in the nonmagnetic layer include nonmagnetic inorganic powder and carbon black. The non-magnetic inorganic powder is preferably relatively hard, and preferably has a Mohs hardness of 5 or more (more preferably 6 or more). Examples of nonmagnetic inorganic powders include α-alumina, β-alumina, γ-alumina, silicon carbide, chromium oxide, cerium oxide, α-iron oxide, corundum, silicon nitride, titanium carbide, titanium dioxide, silicon dioxide, Mention may be made of boron nitride, zinc oxide, calcium carbonate, calcium sulfate and barium sulfate. These can be used alone or in combination. Of these, titanium dioxide, α-alumina, α-iron oxide, or chromium oxide is preferable. The average particle diameter of the nonmagnetic inorganic powder is preferably in the range of 0.01 to 1.0 μm (preferably 0.01 to 0.5 μm, particularly 0.02 to 0.1 μm).

  Carbon black is added for the purpose of imparting electrical conductivity to the magnetic layer to prevent electrification and ensuring the smooth surface properties of the magnetic layer formed on the nonmagnetic layer. As the carbon black used in the nonmagnetic layer, the carbon black described in the magnetic layer can be used. However, the carbon black used in the nonmagnetic layer preferably has an average particle size of 35 nm or less (more preferably 10 to 35 nm). The normal addition amount of carbon black is 3 to 20 parts by weight, preferably 4 to 18 parts by weight, and more preferably 5 to 15 parts by weight with respect to 100 parts by weight of the total nonmagnetic inorganic powder in the nonmagnetic layer. Part.

  As the lubricant, the fatty acid or fatty acid ester described in the magnetic layer can be used. The addition amount of the lubricant is usually in the range of 0.2 to 20 parts by weight with respect to 100 parts by weight of the total nonmagnetic powder of the nonmagnetic layer.

  As the binder for the nonmagnetic layer, the binders described for the magnetic layer described above can be used. The binder is usually used in the range of 5 to 50 parts by weight (preferably 10 to 30 parts by weight) with respect to 100 parts by weight of the nonmagnetic powder of the nonmagnetic layer. In the case of using a combination of vinyl chloride resin, polyurethane resin, and polyisocyanate as binders in the nonmagnetic layer, 5 to 70% by weight of vinyl chloride resin and 2 to 50 polyurethane resin in all binders. It is preferred to use such that the polyisocyanate is included in an amount ranging from 2% to 50% by weight. In the nonmagnetic layer, an optional component that can be added to the magnetic layer may be added.

  In the case of a magnetic tape having a non-magnetic layer, the method for forming the magnetic layer and the non-magnetic layer is not particularly limited, but the magnetic layer is a coating formed after applying the non-magnetic layer coating liquid on the base film. It is preferably formed by using a so-called wet-on-wet coating method in which a magnetic layer coating solution is applied to a layer (nonmagnetic layer) while it is in a wet state.

  Examples of the application method by the wet-on-wet method include the following methods.

  (1) Using a gravure coating, roll coating, blade coating, or extrusion coating apparatus, a nonmagnetic layer is first formed on the base film. While the nonmagnetic layer is in a wet state, the base film pressurizing type A method of forming a magnetic layer with a roux coating device (see Japanese Patent Laid-Open Nos. 60-238179, 1-46186, and 2-265672).

  (2) A method of forming a magnetic layer and a nonmagnetic layer on a base film almost simultaneously using a coating apparatus comprising a single coating head provided with two slits for coating solution (Japanese Patent Laid-Open No. 63-88080, (See JP-A-2-17921 and JP-A-2-265672).

  (3) A method in which a magnetic layer and a nonmagnetic layer are formed almost simultaneously on a base film using an extrusion coating apparatus with a backup roller (see JP-A-2-174965). The nonmagnetic layer and the magnetic layer are preferably formed using a simultaneous multilayer coating method.

  The surface of the back coat layer of the magnetic tape tends to be transferred to the surface of the magnetic layer while the tape is wound. For this reason, it is preferable that the surface of the back coat layer also has relatively high smoothness. The surface of the back coat layer of the magnetic tape is preferably adjusted so that its surface roughness Ra (centerline average roughness with a cutoff of 0.08 mm) is in the range of 0.003 to 0.060 μm. . The surface roughness can be adjusted by the material of the calendar roller to be used, its surface property, pressure, speed, etc., in the surface treatment process using the calendar after the formation of the coating film.

  The magnetic layer of a magnetic tape having a single-layer structure having a magnetic layer on one side of the base film and a backcoat layer on the other side, manufactured according to the manufacturing method of the present invention, has a thickness of 1.0 to 3 It is preferably in the range of 0.0 μm (more preferably, 1.5 to 2.5 μm).

  The total thickness of the magnetic tape having this configuration is preferably in the range of 4.0 to 12.0 μm, more preferably 4.0 to 10.0 μm.

  The thickness of the back coat layer is preferably in the range of 0.1 to 1.0 μm (more preferably 0.2 to 0.8 μm).

  The magnetic layer of the magnetic tape having a nonmagnetic layer preferably has a thickness in the range of 0.01 to 1.0 μm (more preferably 0.05 to 0.5 μm).

  The thickness of the nonmagnetic layer is preferably in the range of 0.01 to 3.0 μm (more preferably 0.5 to 2.5 μm).

  The ratio of the thickness of the magnetic layer to the thickness of the nonmagnetic layer is preferably in the range of 1: 2 to 1:15 (more preferably 1: 5 to 1:12).

  The total thickness of the magnetic tape having the nonmagnetic layer and the thickness of the backcoat layer are preferably in the same range as the magnetic tape having the single layer structure.

  The effect by the structure of this invention is demonstrated by the following tests.

  After applying a base film with a thickness of 9 μm by a general magnetic tape manufacturing method, drying and calendering, the core material (CFRP and AL (aluminum)) and outer diameter D (φ150 mm, φ300 mm, φ400 mm, φ600 mm, The magnetic film was manufactured by heat-treating the wound base film, and the wrinkle generation state and the dropout generation state were inspected for each core.

  The heat treatment was performed at a temperature of 80 ° C. for 24 hours, and the dropout was measured using a DLT (Digital Linear Tape) system on the manufactured magnetic tape.

  The results of the inspection are shown in Table 1 below.

表１に示すように、シワとドロップアウトは、巻芯の材質がＣＦＲＰ、外径Ｄの範囲がφ４００ｍｍ〜φ６００ｍｍのときに良好な結果が得られることが確認できた。

As shown in Table 1, it was confirmed that the wrinkles and dropouts were good when the core material was CFRP and the outer diameter D ranged from φ400 mm to φ600 mm.

Diagram showing the calendar process Diagram showing heat treatment process The figure which shows an example of a core

Explanation of symbols

C ... Calendar roller, G ... Guide roller, F ... Base film, S ... Core, 10 ... Calendar part, 20 ... Constant temperature chamber

Claims (3)

In the heat treatment method of the film heat-treated in a state where the belt-like flexible film is wound around the core,
A method for heat-treating a film, characterized in that the core material is CFRP and the outer diameter is 400 mm or more and 600 mm or less.   The film heat treatment method according to claim 1, wherein the film is a film having a magnetic layer coated on the surface thereof.   A film that is heat-treated by the heat treatment method according to claim 1.

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