JP4406885B2 - Film winding method and magnetic tape manufacturing method - Google Patents

Description

The present invention relates to a film winding method and a magnetic tape manufacturing method , and more particularly to a film winding method and a magnetic tape manufacturing method in which a magnetic layer is applied and formed on the surface.

  In the manufacturing process of a magnetic tape, the operation | work which winds a strip | belt-shaped flexible base film in roll shape is performed in multiple times. This winding operation is performed by winding the base film around the core, but in order to prevent winding wrinkles and winding slipping at the time of winding, the contact roller is pressed against the base film that has been wound up conventionally. Winding is done.

For example, Patent Document 1 proposes a method of winding a contact roller having a Shore A hardness of 80 ° or more and 85 ° or less against a base film that is being wound. In Patent Document 2, the surface friction coefficient is set. A method has been proposed in which a contact roller, which is lower at both axial ends than an axially central portion, is wound while being pressed against a base film being wound. Patent Document 3 proposes a method of winding a plurality of contact rollers while pressing them against a base film being wound. Patent Document 4 discloses a base that is winding a plurality of contact rollers having different hardnesses. A method of winding while pressing against a film has been proposed. Patent Document 5 proposes a method in which a contact roller pressed against a base film is rotationally driven, and the base film is wound around a core while controlling the rotational speed and torque.
Japanese Patent Laid-Open No. 5-77994 JP 2002-348002 A JP 2001-307321 A JP 2001-266341 A JP 2004-307153 A

  However, in the conventional winding method using the contact roller, when the base film is wound to some extent, there is a problem that wrinkles are generated at the portion where the contact roller is pressed and the yield decreases. Further, there is a problem that the winding hardness is different between the core side and the outer peripheral side, and the quality is not constant.

This invention is made | formed in view of such a situation, and it aims at providing the winding method of the film which can prevent generation | occurrence | production of wrinkles, and can make quality constant, and the manufacturing method of a magnetic tape .

In order to achieve the above object, the invention according to claim 1 is a film winding method in which a belt-like flexible film is wound around a core, and the film wound around the core has a hardness of 70 ° (JIS K6301A). ) Wrapped on the first rubber contact roller and guided to the core, the first contact roller is pressed against the outer peripheral surface of the film wound around the core, and further has a hardness of 40 ° (JIS K6301A) A method for winding a film, in which the following rubber second contact roller is pressed against and pressed against the outer peripheral surface of the film wound around the core, and the film is wound around the core. Thus, at the start of winding, “the pressing force of the first contact roller ≦ the pressing force of the second contact roller” and finally “the pressing force of the first contact roller> the second contact roller” So that the pressing force of Kutorora ", wherein the first by changing the relationship between the pressing force of the contact roller and the second contact roller winding the film to the winding core.

  In the case of winding the film while pressing the rubber contact roller against the film wound around the core, the inventor of the present application emphasizes the accumulation of the film due to winding when the contact roller has low hardness. It has been found that nip pressure distribution occurs and wrinkles occur. In addition, the difference in winding hardness between the winding core side and the outer peripheral side is due to the difference in hardness between the winding core and the film. As a result, depending on the number of windings of the film, the hardness of the film and the contact roller at the contact roller pressing portion I found out that this was because the relationship changed.

Therefore, in the first aspect of the invention, the film is wrapped around the first contact roller made of rubber having a hardness of 70 ° or more and guided to the core, and the film wound around the core by the first contact roller. The outer periphery of the film is further pressed, and the outer peripheral surface of the film wound around the core is pressed by a rubber second contact roller having a hardness of 40 ° or less, and the film is wound up. The relationship of the pressing force of the second contact roller was adjusted. That is, at the start of winding, the first contact roller and the second contact roller are set so that “first contact roller ≦ second contact roller” and finally “first contact roller> second contact roller”. The film was wound by changing the relationship of the pressing force.
By winding the film in this way, wrinkles that occur during winding can be prevented, and the yield can be improved. Further, the difference in winding hardness between the core side and the outer peripheral side of the film wound around the core becomes small, and the quality becomes constant.

In order to achieve the above object, a film winding method according to claim 1, wherein the film is coated with a magnetic layer on one surface and a back coat layer on the other surface. overall thickness which is formed, the film der of 4.0~12.0μm is, after being wound on the winding core, said been unwound from the winding core, is cut into a plurality of tape film and wherein the der Rukoto.

  According to invention of Claim 2, the film by which the magnetic layer was apply-formed on the surface is wound up with the winding method of Claim 1.

According to a third aspect of the present invention, in order to achieve the above object, a step of applying and forming a magnetic layer on one surface of a belt-like flexible film and a backcoat layer on the other surface, and a magnetic layer and a backcoat A step of winding a film on which a layer has been formed in a roll form around a core, and a step of rewinding the film in a roll state after the coating process and passing through a plurality of calendar rollers installed so as to be in contact with each other And a step of winding the calendered film in a roll form around the core, a step of placing the calendered roll state film in a temperature-controlled room at a predetermined temperature as it is in a roll state, and leaving it for a predetermined time to heat-treat, In the method of manufacturing a magnetic tape comprising the steps of unwinding the roll-state film after heat treatment and cutting the film into a plurality of magnetic tapes, The film wound around the core is wrapped around a rubber first contact roller having a hardness of 70 ° (JIS K6301A) or more and guided to the core, and the first contact roller is wound around the core. Pressing and pressing the outer peripheral surface against a rubber second contact roller having a hardness of 40 ° (JIS K6301A) or less against the outer peripheral surface of the film wound around the core, and pressing the film At the time of winding around the winding core and starting winding, “pressing force of the first contact roller ≦ pressing force of the second contact roller” and finally “pressing force of the first contact roller> pressing of the second contact roller” The film is wound around the core by changing the relationship between the pressing force of the first contact roller and the second contact roller so that the pressure becomes “pressure”. And features.

According to the film winding method and the magnetic tape manufacturing method according to the present invention, the generation of wrinkles can be prevented and the yield can be improved. In addition, the difference in hardness between the core side and the outer peripheral side can be reduced to achieve a certain quality.

Hereinafter, the best mode for carrying out the film winding method and the magnetic tape manufacturing method according to the present invention will be described with reference to the accompanying drawings. In the present embodiment, a case where 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 surface and a back coat layer is formed on the other surface of a strip-shaped flexible base film fed from a raw roll (for example, a width of 300 mm or more and a length of 1000 m or more). 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, the roll-shaped base film after the coating treatment is rewound, and the surface is flattened through a plurality of calendar rollers installed so as to be in contact with each other. The base film having a smooth surface is wound around a core and formed into a roll shape.

  In the heat treatment step, the base film F in a roll state after the calendar process is placed in a temperature-controlled room at a predetermined temperature while being in a roll state, and is left for a predetermined time to perform heat treatment.

  In the slitting process, the rolled base film F after the heat treatment is rewound and cut into a plurality of magnetic tapes.

Now, as described above, in the magnetic tape manufacturing process, the base film is wound a plurality of times. During this winding, in order to eliminate air and prevent winding wrinkles and slipping, rubber is used. Winding may be performed using a contact roller made of metal.
However, when the base film is wound using a rubber contact roller, when the base film is wound to some extent, wrinkles are generated at the contact roller pressing portion, or the wound film core is wound. There is a problem in that the winding hardness can be separated between the side and the outer peripheral side, and the quality is not constant.

  The inventor of the present application has found that the hardness of the contact roller is related to the cause of the occurrence of the wrinkles. That is, when the hardness of the contact roller is low, it has been found that when the unevenness of the base film is emphasized by accumulation by winding, a nip pressure distribution is generated and wrinkles are generated. In addition, the winding hardness is different between the core side and the outer peripheral side of the wound base film because the hardness of the core and the hardness of the base film are different. It has been found that the hardness relationship between the base film taken and the contact roller changes.

  Therefore, in the manufacturing process of the magnetic tape of the present embodiment, the base film is wound as follows to prevent wrinkles and winding hardness from being separated during winding. That is, as shown in FIG. 1, a base film F wound around a core S is wrapped around a first contact roller C1 having high hardness (hardness of 70 ° or more) and guided to the core S, and the first contact roller The outer peripheral surface of the base film F wound around the core S by pressing the outer periphery of the base film F wound around the core S with C1 and further wound with the second contact roller C2 having a low hardness (hardness of 40 ° or less). The base film F is wound around the core S by pressing. At this time, the relationship between the pressing force of the first contact roller C1 and the second contact roller C2 is “the pressing force of the first contact roller C1 ≦ the pressing force of the second contact roller C2” at the start of winding. Is changed so that “the pressing force of the first contact roller C1> the pressing force of the second contact roller C2”.

  Thus, by winding up the base film F, the wrinkle which generate | occur | produces at the time of winding can be prevented, and a yield can be improved. Moreover, the difference of the winding hardness of the core side of the base film F wound up by the core F and the outer peripheral side becomes small, and quality becomes constant.

  In addition, about the form which changes the pressing force of the 1st contact roller C1 and the 2nd contact roller C2, you may make it change gradually and may make it change in steps.

  Further, the method for controlling the total pressure of the first contact roller C1 and the second contact roller C2 is not particularly limited, but it is preferable that the total pressure be constant or gradually increased.

  Further, the diameters of the first contact roller C1 and the second contact roller C2 are not particularly limited, and those having different diameters may be used. For example, the diameter may be changed depending on the place to be pressed.

  Furthermore, the 1st contact roller C1 and the 2nd contact roller C2 should just be a rubber | gum outer periphery, and the specific structure is not specifically limited. Also, the type of rubber is not particularly limited, and for example, NBR (Nitrile-Butadiene Rubber), EPDM (ethylene-propyleneterpolymer), or the like may be used.

  In the present embodiment, the two contact rollers, the first contact roller C1 and the second contact roller C2, are installed to wind up the base film F. However, the number of contact rollers installed is It is not limited to this. What is necessary is just to install the 1st contact roller C1 and the 2nd contact roller C2 which satisfy | fill the said requirement at least, and you may make it install another contact roller in addition. Further, the installation location is not particularly limited.

  The material of the core S is not particularly limited and may be a metal such as aluminum, FRP (Fiber Reinforced Plastics) or CFRP (Carbon Fiber Reinforced Plastics). ) Etc. Similarly, the diameter of the core S is not particularly limited.

  In the present embodiment, the case where the present invention is used in the manufacturing process of the magnetic tape has been described as an example. However, the application of the present invention is not limited to this, and winding of other film-like products is performed. Can be used similarly. In particular, a remarkable effect can be obtained by using it for winding a coating-type film product.

  Further, in the present embodiment, the case where the magnetic tape is manufactured by the process of [coating] → [calendar] → [heat treatment] → [slit] has been described as an example. However, the manufacturing process of the magnetic tape in which the present invention can be used. However, the present invention is not limited to this. For example, the winding method according to the present invention is also applied in the case of manufacturing in the process of [Coating] → <Heat treatment> → [Calendar] → [Heat treatment] → [Slit] → <Surface treatment / heat treatment / servo light> → [Enrollment]. Can be used to wind the base film (in parentheses are steps performed as necessary).

  In addition, when the present invention is used in the manufacturing process of the magnetic tape, the material of the base film is not particularly limited, and base films of various materials such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and aramid are used. The present invention can be used to wind up.

  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-Fe2 O3, Fe3 O4, FeOx (x = 1.33 to 1.5), CrO2, Co-containing γ-Fe2 O3, and Co-containing FeOx (x = 1.33 to 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 preferably has a specific surface area of 30 to 70 m ² / g and a 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-like hexagonal ferrite powder has a specific surface area of 25 to 65 m ² / g, a plate-like 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, and 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 necessary 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 the 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 (Cr2 O3), 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 binders, -COOM, -SO3 M, -OSO3 M, -P = O (OM) 2, -OP may be used as necessary to obtain better dispersibility and durability of the resulting layer. ═O (OM) 2 (M represents a hydrogen atom or an alkali metal base), —OH, —NR 2, —N + R 3 (R represents a hydrocarbon group), epoxy group, —SH, —CN It is preferable to use at least one polar group selected from the above 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),
PRINTEX 75 (17 nm) (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 (Cr2 O3). 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 size 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.

  A base film is applied, dried, and calendered by a general magnetic tape manufacturing method, and then wound by changing the hardness and pressing force of the first contact roller C1 with a winding device having the configuration shown in FIG. And the core hardness difference (the difference in winding hardness between the core side and the outer peripheral side) was inspected (the hardness and pressing force of the second contact roller C2 were constant).

  The first contact roller C1 and the second contact roller C2 made of NBR were used, and the second contact roller C2 had a hardness of 40 ° (JIS K6301A). Further, the core difference in winding hardness was measured by inserting a pressure sensitive sheet (trade name: Prescale (manufactured by Fuji Photo Film Co., Ltd.)) into the winding part.

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

表１に示すように、シワは、第１コンタクトローラＣ１の硬度が７０°以上になると発生しなくなることが確認できた。また、巻き硬さの芯外差は、「第１コンタクトローラＣ１の押圧力≦第２コンタクトローラＣ２の押圧力」で巻き取りを開始し、最終的に「第１コンタクトローラＣ１の押圧力＞第２コンタクトローラＣ２の押圧力」としたときに少なくなることが確認できた。

As shown in Table 1, it was confirmed that the wrinkles were not generated when the hardness of the first contact roller C1 was 70 ° or more. Further, the winding difference of the center of winding hardness starts winding with “pressing force of first contact roller C1 ≦ pressing force of second contact roller C2”, and finally “pressing force of first contact roller C1> It was confirmed that the pressure was reduced when the pressure of the second contact roller C2 was set.

The figure which shows schematic structure of a winding device

Explanation of symbols

  F ... Base film, S ... Core, C1 ... First contact roller, C2 ... Second contact roller

Claims (3)

In the film winding method for winding the belt-shaped flexible film around the core,
The film wound around the core was wrapped around a rubber first contact roller having a hardness of 70 ° (JIS K6301A) or more and guided to the core, and the first contact roller was wound around the core. Press and press against the outer peripheral surface of the film, and press and press the second contact roller made of rubber having a hardness of 40 ° (JIS K6301A) or less against the outer peripheral surface of the film wound around the core. Is a method of winding a film around the core,
At the start of winding, “the pressing force of the first contact roller ≦ the pressing force of the second contact roller” and finally “the pressing force of the first contact roller> the pressing force of the second contact roller” A method for winding a film, wherein the film is wound around the core by changing the pressing force relationship between the first contact roller and the second contact roller. The film, the magnetic layers on one surface, the thickness of the whole of the back coat layer on the other surface is formed by coating, film der of 4.0~12.0μm is, wound on the winding core later, it is unwound from the winding core, winding method of the film according to claim 1, wherein the film der Rukoto to be cut into a plurality of tapes. A step of applying and forming a magnetic layer on one side of the belt-like flexible film and a back coat layer on the other side, and a step of winding the film on which the magnetic layer and the back coat layer have been formed on a roll in a roll shape And a step of rewinding the film in a roll state after the coating treatment and performing a calendering process between a plurality of calender rollers installed so as to be in contact with each other, and a step of winding the calendered film into a roll around a core And a process of placing the roll-processed film after the calendar process in a roll-state in a temperature-controlled room at a predetermined temperature, leaving the film for a predetermined time and heat-treating, and unwinding the roll-processed film after the heat-treatment to form a plurality of magnetic tapes. In the manufacturing method of the magnetic tape which consists of the process of cutting,
The step of winding the film around the core is guided to the core by wrapping the film wound around the core on a first contact roller made of rubber having a hardness of 70 ° (JIS K6301A) or higher. The contact roller is pressed against and pressed against the outer peripheral surface of the film wound around the core, and a rubber second contact roller having a hardness of 40 ° (JIS K6301A) or less is further wound around the core. Pressing and pressing the outer peripheral surface, the film is wound around the core, and at the start of winding, "the pressing force of the first contact roller ≦ the pressing force of the second contact roller" The relationship between the pressing force of the first contact roller and the second contact roller is changed so that the pressing force of one contact roller> the pressing force of the second contact roller ”. Manufacturing method of a magnetic tape, characterized in that winding the film to the winding core Te.

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