JP2005222609A - Cleaning tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning tape for magnetic recording medium in which head wear is less and dirt attached to the head can be removed efficiently while keeping good a contact state of the head and a medium. <P>SOLUTION: This is a cleaning tape in which a cleaning layer is provided at a plane of one side of a supporter. The tape is characterized in that bending rigidity in the longitudinal direction of the tape is 0.0002-0.0004N mm<SP>2</SP>. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cleaning tape for removing dirt on a magnetic head of an apparatus alloy system that performs recording and reproduction on a magnetic recording medium such as a video tape and a data tape.

Until now, in the field of broadcasting, single layer coated metal tapes using ferromagnetic metal powder and multi-layered metal tapes that have improved the output by thinning the magnetic layer by simultaneously coating nonmagnetic layers. Have been used. With the widespread use of high-quality broadcasting such as high-definition broadcasting and digital terrestrial broadcasting, a recording medium having a higher recording density than before is desired. In the field of data, the amount of information handled has increased dramatically, and the rotating head system used for broadcasting has come to be used. In this field, a backup tape having a high recording density and high reliability is desired as in broadcasting.
In such a situation, in order to improve the linear recording density of the recording medium, the surface property of the magnetic surface becomes more and more smooth, and there is a concern that the running durability is deteriorated due to an increase in the friction coefficient. Further, since the volume recording density is lowered to increase the capacity, it is unavoidable to make the recording medium thinner, and the running durability such as tape edge damage is becoming increasingly severe. Further, it is very difficult to keep the contact state with the head uniform by thinning the tape, and high strength materials such as PEN and aramid have been used for the support in order to ensure the tape strength. On the other hand, research and development on the shape of a magnetic head has been actively conducted, and a head having a structure capable of obtaining a thin tape and good contact has been used. However, it is difficult to maintain a good head contact as the track becomes narrower due to the improvement in recording density. Further, due to the narrowing of the track, it is important to efficiently remove the dirt adhering to the head because a signal is lost even with a minute foreign matter. Until now, the dirt adhering to the head has been removed using a special cleaning tape. For example, a dedicated cleaning tape is included in the DAT 72 manufactured by HP. These are designed to remove dirt adhering to the head by setting the wearability of the cleaning layer to a large value, but the head wear is large, and travel time is limited. Further, since the shape of the head R is changed, the contact state between the head and the medium may be deteriorated.

Japanese Patent Publication No. 7-36210 JP 2002-183918 A JP 2002-313055 A

  An object of the present invention is to provide a cleaning tape for a magnetic recording medium that can reduce the wear of the head and efficiently remove dirt adhered to the head while maintaining a good contact state between the head and the medium.

The above-mentioned subject of the present invention is a cleaning tape comprising a cleaning layer provided on one surface of a support, wherein the bending rigidity in the tape longitudinal direction is 0.0002 to 0.0004 N · mm ^2. Can be achieved with tape.

The present invention can efficiently remove dirt adhering to the head and restore the error rate to a normal state by using a cleaning tape having a bending rigidity in the longitudinal direction of the tape of 0.0002 to 0.0004 N · mm ^2. I can do it.

In the present invention, since the bending rigidity of the cleaning tape is specified to be lower than before, the contact pressure between the cleaning tape and the head at both ends of the head is increased, and it is considered that the effect of removing dirt adhered to the bottom can be achieved.
As a means for controlling the bending rigidity, it is possible to select a constituent material of the cleaning tape. Specifically, it is possible to select a support having a Young's modulus of 6000 to 10000 MPa and a thickness of 2.5 to 3.5 μm, or a cleaning layer having a Vickers hardness of 800 MPa or less.

Hereinafter, the cleaning tape of the present invention will be described in detail.
[Cleaning layer]
In the present invention, the layer structure is not particularly limited as long as the cleaning layer is provided on one surface of the support.
In the present invention, the lower layer can be provided between the cleaning layer (hereinafter also referred to as “upper layer”) and the support. The upper and lower layers can be provided with an upper layer after the lower layer is applied, either in a wet state (Wet on Wet) or after drying (Wet on Dry).

[Ferromagnetic metal powder]
As the cleaning layer of the present invention, it is preferable to use a magnetic layer of a magnetic recording medium.
The ferromagnetic metal powder used for the cleaning layer is preferably a ferromagnetic alloy powder containing α-Fe as a main component. These ferromagnetic powders include Al, Si, S, Sc, Ca, Ti, V, Cr, Cu, Y, Mo, Rh, Pd, Ag, Sn, Sb, Te, Ba, Ta, other than predetermined atoms. It may contain atoms such as W, Re, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Sm, P, Co, Mn, Zn, Ni, Sr, and B. In particular, it is preferable to contain at least one of Al, Si, Ca, Y, Ba, La, Nd, Sm, Co, Ni, and B in addition to α-Fe, and at least one of Co, Y, Al, Nd, and Sm. More preferably, one is included. The Co content is preferably 0 atomic percent to 40 atomic percent, more preferably 5 atomic percent to 35 atomic percent, and still more preferably 10 atomic percent to 35 atomic percent with respect to Fe. The content of Y is preferably 1.5 atom% or more and 12 atom% or less, more preferably 3 atom% or more and 10 atom% or less, more preferably 3 atom% or more and 9 atom% or less. Al is preferably 1.5 atomic percent or more and 13 atomic percent or less, more preferably 3 atomic percent or more and 11 atomic percent or less, and more preferably 4 atomic percent or more and 10 atomic percent or less. These ferromagnetic powders may be treated in advance with a dispersant, lubricant, surfactant, antistatic agent, etc. described later before dispersion. Specifically, Japanese Patent Publication No. 44-14090, Japanese Patent Publication No. 45-18372, Japanese Patent Publication No. 47-22062, Japanese Patent Publication No. 47-22513, Japanese Patent Publication No. Sho 46-28466, Japanese Patent Publication No. Sho 46-38755, Japanese Patent Publication No. 47 No. -4286, Japanese Patent Publication No. 47-12422, Japanese Patent Publication No. 47-17284, Japanese Patent Publication No. 47-18509, Japanese Patent Publication No. 47-18573, Japanese Patent Publication No. 39-10307, Japanese Patent Publication No. 46-39639, US Patent No. 3026215. No. 3033131, No. 3100194, No. 3420005, No. 3338914, and the like.

  The ferromagnetic metal powder may contain a small amount of hydroxide or oxide. What was obtained by the well-known manufacturing method of ferromagnetic metal powder can be used, and the following method can be mentioned. Method of reducing complex organic acid salt (mainly oxalate) with reducing gas such as hydrogen, method of reducing iron oxide with reducing gas such as hydrogen to obtain Fe or Fe-Co particles, metal carbonyl compound A method of thermal decomposition, a method of reducing by adding a reducing agent such as sodium borohydride, hypophosphite, or hydrazine to an aqueous solution of a ferromagnetic metal, and evaporating the metal in a low-pressure inert gas to form a fine powder. How to get. The ferromagnetic metal powder obtained in this manner is a known slow oxidation treatment, that is, a method of drying after being immersed in an organic solvent, and after being immersed in an organic solvent, an oxygen-containing gas is fed to form an oxide film on the surface and then dried. Any of the methods of forming an oxide film on the surface by adjusting the partial pressure of oxygen gas and inert gas without using an organic solvent can be used.

When the ferromagnetic metal powder of the magnetic layer of the present invention is expressed by a specific surface area according to the BET method, it is 45 to 80 m ² / g, preferably 50 to 70 m ² / g. Noise is high at 45 m ² / g or less, and surface properties are difficult to obtain at 80 m ² / g or more. The crystallite size of the ferromagnetic metal powder of the magnetic layer of the present invention is 80 to 180 angstrom, preferably 100 to 180 angstrom, and more preferably 110 to 175 angstrom. The average major axis length of the ferromagnetic metal powder is preferably 30 to 150 nm, and more preferably 30 to 100 nm. The acicular ratio of the ferromagnetic metal powder is preferably 3 or more and 15 or less, and more preferably 5 or more and 12 or less. The saturation magnetization (σs) of the ferromagnetic metal powder is 100 to 200 A · m ² / kg (emu / g), preferably 120 to 180 A · m ² / kg.

The water content of the ferromagnetic metal powder is preferably 0.01-2% by mass. It is preferable to optimize the moisture content of the ferromagnetic metal powder depending on the type of the binder. The pH of the ferromagnetic metal powder is preferably optimized depending on the combination with the binder used. The range is usually from 4 to 12, but preferably from 6 to 10. The ferromagnetic metal powder may be surface-treated with Al, Si, P, or an oxide thereof as required. The amount thereof is usually 0.1 to 10% by mass with respect to the ferromagnetic metal powder, and the surface treatment is preferable because adsorption of a lubricant such as a fatty acid is 100 mg / m ² or less. The ferromagnetic metal powder may contain inorganic ions such as soluble Na, Ca, Fe, Ni, and Sr. Although it is preferable that these are essentially not present, if they are 200 ppm or less, they do not particularly affect the characteristics. The ferromagnetic metal powder used in the present invention preferably has fewer vacancies, and its value is 20% by volume or less, more preferably 5% by volume or less. As for the shape, any of needle shape, rice grain shape, or spindle shape may be used as long as the above-mentioned characteristics regarding the particle size are satisfied. The SFD (switching field distribution) of the ferromagnetic metal powder itself is preferably small, and preferably 0.8 or less. It is necessary to reduce the Hc distribution of the ferromagnetic metal powder. In order to reduce the distribution of Hc, there are methods such as improving the particle size distribution of goethite and preventing sintering in the ferromagnetic metal powder.

[Underlayer]
Next, the detailed content regarding a lower layer is demonstrated. The lower layer of the present invention comprises at least a resin, and preferably includes a powder, for example, an inorganic powder or an organic powder dispersed in a resin. The inorganic powder is usually preferably a non-magnetic powder, but the magnetic powder may be mixed and used within a range that does not substantially affect the electromagnetic conversion characteristics.
The nonmagnetic powder can be selected from, for example, inorganic compounds such as metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, and metal sulfides. Examples of inorganic compounds include α-alumina, β-alumina, γ-alumina, θ-alumina, silicon carbide, chromium oxide, cerium oxide, α-iron oxide, hematite, goethite, corundum, silicon nitride with an α conversion rate of 90% or more. , Titanium carbide, titanium oxide, silicon dioxide, tin oxide, magnesium oxide, tungsten oxide, zirconium oxide, boron nitride, zinc oxide, calcium carbonate, calcium sulfate, barium sulfate, molybdenum disulfide, etc. are used alone or in combination . Particularly preferred are titanium dioxide, zinc oxide, iron oxide and barium sulfate because of their small particle size distribution and many means for imparting functions, and more preferred are titanium dioxide and alpha iron oxide. The average particle size of these non-magnetic powders is preferably 0.005 to 2 μm. However, if necessary, non-magnetic powders having different particle sizes can be combined, or a single non-magnetic powder can have the same effect by widening the particle size distribution. It can also be given. The average particle size of the nonmagnetic powder is particularly preferably 0.01 μm to 0.2 μm. In particular, when the nonmagnetic powder is a granular metal oxide, the average particle diameter is preferably 0.08 μm or less, and when the nonmagnetic powder is an acicular metal oxide, the average major axis length is preferably 0.3 μm or less, and 0.2 μm. The following is more preferable. The tap density is 0.05 to 2 g / ml, preferably 0.2 to 1.5 g / ml. The water content of the nonmagnetic powder is 0.1 to 5% by mass, preferably 0.2 to 3% by mass, and more preferably 0.3 to 1.5% by mass. The pH of the nonmagnetic powder is usually 2 to 11, but the pH is particularly preferably between 3 and 10. The specific surface area of the non-magnetic powder is 1 to 100 m ² / g, preferably 5 to 80 m ² / g, more preferably 10 to 70 m ² / g. The crystallite size of the nonmagnetic powder is preferably 0.004 μm to 1 μm, and more preferably 0.04 μm to 0.1 μm. The oil absorption using DBP (dibutyl phthalate) is 5 to 100 ml / 100 g, preferably 10 to 80 ml / 100 g, and more preferably 20 to 60 ml / 100 g. The specific gravity is 1 to 12, preferably 3 to 6. The shape may be any of a needle shape, a spherical shape, a polyhedron shape, and a plate shape. The Mohs hardness is preferably 4 or more and 10 or less. The nonmagnetic powder has an SA (stearic acid) adsorption amount of 1 to 20 μmol / m ² , preferably ² to 15 μmol / m ² , and more preferably 3 to 8 μmol / m ² . The surface of these nonmagnetic powders is preferably subjected to surface treatment and Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , SnO ₂ , Sb ₂ O ₃ , ZnO, and Y ₂ O ₃ are preferably present. Particularly preferred for dispersibility are Al ₂ O ₃ , SiO ₂ , TiO ₂ and ZrO ₂ , but more preferred are Al ₂ O ₃ , SiO ₂ and ZrO ₂ . These may be used in combination or may be used alone. Further, a co-precipitated surface treatment layer may be used depending on the purpose, and a method in which alumina is first present and then silica is present in the surface layer, or vice versa may be employed. The surface treatment layer may be a porous layer depending on the purpose, but it is generally preferable that the surface treatment layer is homogeneous and dense.

  Specific examples of the non-magnetic powder used in the lower layer of the present invention include Showa Denko Nano Tight, Sumitomo Chemical HIT-100, ZA-G1, Toda Kogyo α Hematite DPN-250, DPN-250BX, DPN- 245, DPN-270BX, DPN-500BX, DBN-SA1, DBN-SA3, Titanium oxide made by Ishihara Sangyo TTO-51B, TTO-55A, TTO-55B, TTO-55C, TTO-55S, TTO-55D, SN-100 , Α-hematite E270, E271, E300, E303, Titanium Industrial Titanium oxide STT-4D, STT-30D, STT-30, STT-65C, α-hematite α-40, Teica MT-100S, MT-100T, MT- 150W, MT-500B, MT-600B, MT-100F, MT-500H FINEX-25, BF-1, BF-10, BF-20, ST-M, Sakai Chemical Co., Ltd., DEFIC-Y, DEFIC-R, Nippon Aerosil AS2BM, TiO2P25, Ube Industries 100A, 500A, and What baked it is mentioned. Particularly preferred nonmagnetic powders are titanium dioxide and α-iron oxide.

Carbon black can be mixed in the lower layer to lower the surface electrical resistance Rs, which is a known effect, and to reduce the light transmittance. As the type of carbon black, rubber furnace, rubber thermal, color black, acetylene black, and the like can be used. The lower layer carbon black should have the following characteristics optimized depending on the desired effect, and the effect may be obtained by using it together.
Lower Ca - specific surface area of carbon black is 100 to 500 m ² / g, preferably 150~400m ² / g, DBP oil absorption 20 to 400 ml / 100 g, preferably from 30 to 400 ml / 100 g. The average particle diameter of carbon black is 5 nm to 80 nm, preferably 10 to 50 nm, more preferably 10 to 40 nm. Carbon black preferably has a pH of 2 to 10, a water content of 0.1 to 10% by mass, and a tap density of 0.1 to 1 g / ml. As specific examples of the carbon black used in the present invention, BLACKPEARLS 2000, 1300, 1000, 900, 800, 880, 700, VULCAN XC-72 manufactured by Cabot Corporation, # 3050B, # 3150B manufactured by Mitsubishi Kasei Kogyo Co., Ltd. # 3250B, # 3750B, # 3950B, # 950, # 650B, # 970B, # 850B, MA-600, MA-230, # 4000, # 4010, CONDUCTEX SC, Raven 8800, 8000, 7000 manufactured by Columbian Carbon , 5750, 5250, 3500, 2100, 2000, 1800, 1500, 1255, 1250, and Ketjen Black EC manufactured by Akzo. Carbon black may be surface-treated with a dispersant or the like, or may be grafted with a resin or may be obtained by graphitizing a part of the surface. In addition, carbon black may be dispersed in advance with a binder before it is added to the paint. These carbon blacks can be used in a range not exceeding 50% by mass with respect to the inorganic powder and in a range not exceeding 40% by mass of the total mass of the nonmagnetic layer. These carbon blacks can be used alone or in combination. The carbon black that can be used in the present invention can be referred to, for example, “Carbon Black Handbook” (edited by Carbon Black Association).

  Further, an organic powder can be added to the lower layer depending on the purpose. Examples include acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, and phthalocyanine pigment, but polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, and polyfluorinated ethylene resin are also included. Can be used. As the production method, those described in JP-A Nos. 62-18564 and 60-255827 can be used.

  Regarding the binder resin (type and amount) of the lower layer, the type, amount, solvent, and dispersion method of the lubricant / dispersant / additive, known techniques relating to the magnetic layer can be applied.

[Binder]
As the binder used in the present invention, conventionally known thermoplastic resins, thermosetting resins, reactive resins and mixtures thereof are used. The thermoplastic resin has a glass transition temperature of −100 to 150 ° C., a number average molecular weight of 1,000 to 200,000, preferably 10,000 to 100,000, and a degree of polymerization of about 50 to 1,000. .
Examples 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 acetate. There are polymers or copolymers containing polyurethane, vinyl ether, etc. as structural units, polyurethane resins, and various rubber resins. 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-polyamides. Resin, a mixture of polyester resin and isocyanate prepolymer, a mixture of polyester polyol and polyisocyanate, a mixture of polyurethane and polyisocyanate, and the like. These resins are described in detail in “Plastic Handbook” published by Asakura Shoten. It is also possible to use a known electron beam curable resin for each layer. These examples and their production methods are described in detail in JP-A No. 62-256219. The above resins can be used alone or in combination, but preferred are vinyl chloride resin, vinyl chloride vinyl acetate copolymer, vinyl chloride vinyl acetate vinyl alcohol copolymer, vinyl chloride vinyl acetate maleic anhydride copolymer, A combination of at least one selected from the group consisting of a polyurethane resin and a combination of these with a polyisocyanate.

As the structure of the polyurethane resin, known structures such as polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, polyester polycarbonate polyurethane and polycaprolactone polyurethane can be used. For all binding agents indicated herein, if necessary in order to obtain more excellent dispersibility and _{durability, -COOM, -SO 3 M, -OSO} 3 M, -P = O (OM) 2, - O—P═O (OM) ₂ (wherein M is a hydrogen atom or an alkali metal base), —OH, —NR ₂ , —N ⁺ R ₃ (R is a hydrocarbon group), epoxy group, —SH, It is preferable to use one in which at least one polar group selected from —CN, etc. is introduced by copolymerization or addition reaction. The amount of such a polar group is 10 ⁻¹ to 10 ⁻⁸ mol / g, preferably 10 ⁻² to 10 ⁻⁶ mol / g.

Specific examples of these binders used in the present invention include VAGH, VYHH, VMCH, VAGF, VAGD, VROH, VYES, VYNC, VMCC, XYHL, XYSG, PKHH, PKHJ, PKHC, PKFE manufactured by Union Carbide. , Manufactured by Nissin Chemical Industry Co., Ltd., MPR-TA, MPR-TA5, MPR-TAL, MPR-TSN, MPR-TMF, MPR-TS, MPR-TM, MPR-TAO, Denki Kagaku 1000W, DX80, DX81, DX82, DX83, 100FD, Nippon Zeon Co., Ltd. MR-104, MR-105, MR110, MR100, MR555, 400X-110A, Nippon Polyurethane Co., Ltd. Nipporan N2301, N2302, N2304, Dainippon Ink, Pandex T-5105, T-R3080, T- 201, bus - knock D-400, D-210-80, CRISVON 6109,7209, manufactured by Toyobo Co., Ltd. Byron UR8200, UR8300
, UR-8700, RV530, RV280, manufactured by Dainichi Seika Co., Ltd., Daiferamin 4020, 5020, 5100, 5300, 9020, 9022, 7020, Mitsubishi Kasei Co., Ltd., MX5004, Sanyo Kasei Co., Ltd. F310, F210 etc. are mentioned.

The binder used in the lower layer and the cleaning layer of the present invention is used in the range of 5 to 50% by mass, preferably in the range of 10 to 30% by mass with respect to the nonmagnetic powder or magnetic powder. When using a vinyl chloride resin, it is preferable to use 5-30% by weight, when using a polyurethane resin, 2-20% by weight, and polyisocyanate in a range of 2-20% by weight. When head corrosion occurs due to a small amount of dechlorination, it is possible to use only polyurethane or only polyurethane and isocyanate. In the present invention, when polyurethane is used, the glass transition temperature is −50 to 150 ° C., preferably 0 ° C. to 100 ° C., the breaking elongation is 100 to 2000%, and the breaking stress is 0.49 to 98 MPa (0.05 to 10 kg / mm ² ) and the yield point is preferably 0.49 to 98 MPa (0.05 to 10 kg / mm ² ).

  The cleaning tape of the present invention may be composed of two or more layers. Therefore, the amount of binder, the amount of vinyl chloride resin, polyurethane resin, polyisocyanate, or other resin in the binder, the molecular weight of each resin forming the cleaning layer, the amount of polar groups, or the above-mentioned Of course, it is possible to change the physical characteristics of the resin between the layers as required, and rather, it should be optimized in each layer, and a known technique relating to the multilayer magnetic layer can be applied. For example, when changing the amount of binder in each layer, it is effective to increase the amount of binder in the cleaning layer in order to reduce scratches on the surface of the cleaning layer, and in order to improve the head touch to the head, the lower layer binder The amount can be increased for flexibility.

  Examples of the polyisocyanate used in the present invention include tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthylene-1,5- Isocyanates such as diisocyanate, o-toluidine diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, and products of these isocyanates and polyalcohols In addition, polyisocyanate produced by condensation of isocyanates can be used. Commercially available product names of these isocyanates are: Nippon Polyurethane, Coronate L, Coronate HL, Coronate 2030, Coronate 2031, Millionate MR, Millionate MTL, Takeda Made, Takenet D-102, Takenet D-110N, Takenet D-200, Takenet D-202, manufactured by Sumitomo Bayer, Death Module L, Death Module IL, Death Module N, There is a desmodulation HL, etc., and these can be used for each layer alone or in combination of two or more utilizing the difference in curing reactivity.

[Carbon black, abrasive]
As the carbon black used in the magnetic layer of the present invention, a furnace for rubber, a thermal for rubber, a black for color, acetylene black and the like can be used. Specific surface area is 5 to 500 m ² / g, DBP oil absorption is 10 to 400 ml / 100 g, average particle size is 5 nm to 300 nm, pH is 2 to 10, moisture content is 0.1 to 10% by mass, tap density is 0. 1-1g / cc is preferable. Specific examples of carbon black used in the present invention include Cabot Corporation, BLACKPEARLS 2000, 1300, 1000, 900, 905, 800, 700, VULCAN XC-72, Asahi Carbon Corporation, # 80, # 60, # 55, # 50, # 35, manufactured by Mitsubishi Chemical Industries, # 2400B, # 2300, # 900, # 1000, # 30, # 40, # 10B, manufactured by Columbian Carbon, CONDUCTEX SC, RAVEN 150, 50, 40, 15, RAVEN-MT-P, manufactured by Japan EC Co., Ltd., and ketjen black EC. Carbon black may be surface-treated with a dispersant or the like, or may be grafted with a resin or may be obtained by graphitizing a part of the surface. Further, carbon black may be dispersed in advance with a binder before being added to the magnetic paint. These carbon blacks can be used alone or in combination. When carbon black is used, it is preferably used in an amount of 0.1 to 30% by mass relative to the magnetic material. Carbon black functions to prevent the magnetic layer from being charged, reduce the coefficient of friction, impart light-shielding properties, and improve film strength. These differ depending on the carbon black used. Therefore, these carbon blacks used in the present invention are changed in kind, amount and combination in the cleaning layer and the lower layer, and based on the above-mentioned characteristics such as particle size, oil absorption, conductivity, pH and the like. Of course, it is possible to use them properly according to the purpose, but rather they should be optimized in each layer. For the carbon black that can be used in the cleaning layer of the present invention, for example, “Carbon Black Handbook” edited by Carbon Black Association can be referred to.

In the present invention, the abrasive is α-alumina, β-alumina, silicon carbide, chromium oxide, cerium oxide, α-iron oxide, corundum, silicon nitride, silicon carbide, titanium carbide, oxide having an α conversion rate of 90% or more. Known materials having a Mohs hardness of 6 or more, such as titanium, silicon dioxide, boron nitride and diamond, are used alone or in combination. Moreover, you may use the composite_body | complex (what surface-treated the abrasive | polishing agent with the other abrasive | polishing agent) of these abrasive | polishing agents. These abrasives may contain compounds or elements other than the main component, but the effect is not affected if the main component is 90% by mass or more. The average particle size of these abrasives is preferably 0.01 to 2 μm, and in order to improve electromagnetic conversion characteristics, it is preferable that the particle size distribution is narrow. Further, in order to improve the durability, it is possible to combine abrasives having different particle sizes as necessary, or to obtain the same effect by widening the particle size distribution even with a single abrasive. The tap density is preferably 0.3 to ² g / cc, the water content is preferably 0.1 to 5% by mass, the pH is 2 to 11, and the specific surface area is preferably 1 to 30 m ² / g. The shape of the abrasive used in the present invention may be any of a needle shape, a spherical shape, and a dice shape, but those having a corner in a part of the shape are preferable because of high polishing properties. Specifically, AKP-12, AKP-15, AKP-20, AKP-30, AKP-50, HIT-20, HIT-30, HIT-55, HIT-60, HIT-70, HIT- manufactured by Sumitomo Chemical Co., Ltd. 80, HIT-100, Reynolds, ERC-DBM, HP-DBM, HPS-DBM, Fujimi Abrasives, WA10000, Uemura Kogyo, UB20, Nippon Chemical Industry, G-5, Chromex U2, Chromex U1, Toda Kogyo, TF100, TF140, Ibiden, Beta Random Ultra Fine, Showa Mining, B-3, and the like. These abrasives can be added to the lower layer as needed. By adding to the lower layer, the surface shape can be controlled, and the protruding state of the abrasive can be controlled. Of course, the particle size and amount of the abrasive added to the magnetic layer and the lower layer should be set to optimum values.

[Additive]
As the additive used in the cleaning layer and the lower layer of the present invention, those having a lubricating effect, an antistatic effect, a dispersing effect, a plasticizing effect, and the like are used. Molybdenum disulfide, tungsten disulfide, graphite, boron nitride, fluorinated graphite, silicone oil, silicone with polar group, fatty acid-modified silicone, fluorine-containing silicone, fluorine-containing alcohol, fluorine-containing ester, polyolefin, polyglycol, alkyl phosphate ester And alkali metal salts thereof, alkyl sulfates and alkali metal salts thereof, polyphenyl ether, phenylphosphonic acid, α-naphthyl phosphoric acid, phenyl phosphoric acid, diphenyl phosphoric acid, p-ethylbenzenephosphonic acid, phenylphosphinic acid, aminoquinones, various silane couplings Agents, titanium coupling agents, fluorine-containing alkyl sulfates and alkali metal salts thereof, monobasic fatty acids having 10 to 24 carbon atoms (which may contain unsaturated bonds or may be branched). And a metal salt thereof (Li, Na, K, Cu, etc.) or a monovalent, divalent, trivalent, tetravalent, pentavalent, hexavalent alcohol (unsaturated bond) having 12 to 22 carbon atoms. Or an alkoxy alcohol having 12 to 22 carbon atoms (which may contain an unsaturated bond or may be branched), a monobasic fatty acid having 10 to 24 carbon atoms ( Any one of monovalent, divalent, trivalent, tetravalent, pentavalent, and hexavalent alcohols having 2 to 12 carbon atoms (unsaturated bond). Mono-fatty acid ester or di-fatty acid ester or tri-fatty acid ester, fatty acid ester of monoalkyl ether of alkylene oxide polymer, fatty acid amide having 8 to 22 carbon atoms, charcoal An aliphatic amine having a prime number of 8 to 22 can be used.

  Specific examples of these fatty acids include capric acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, and isostearic acid. For esters, butyl stearate, octyl stearate, amyl stearate, isooctyl stearate, butyl myristate, octyl myristate, butoxyethyl stearate, butoxydiethyl stearate, 2-ethylhexyl stearate, 2-octyldodecyl palmitate 2-hexyldecyl palmitate, isohexadecyl stearate, oleyl oleate, dodecyl stearate, tridecyl stearate, oleyl erucate, neopentyl glycol didecanoate, ethylene glycol dioleyl, oleyl alcohol for alcohols , Stearyl alcohol, lauryl alcohol and the like. Nonionic surfactants such as alkylene oxide, glycerin, glycidyl, alkylphenol ethylene oxide adducts, cyclic amines, ester amides, quaternary ammonium salts, hydantoin derivatives, heterocyclics, phosphonium Or cationic surfactants such as sulfoniums, anionic surfactants containing acidic groups such as carboxylic acid, sulfonic acid, phosphoric acid, sulfate ester group, phosphate ester group, amino acids, aminosulfonic acids, amino alcohols Amphoteric surfactants such as sulfuric acid or phosphate esters, alkylbedine type, etc. can also be used. These surfactants are described in detail in “Surfactant Handbook” (published by Sangyo Tosho Co., Ltd.). These lubricants, antistatic agents, and the like are not necessarily 100% pure, and may contain impurities such as isomers, unreacted materials, side reaction products, decomposed products, and oxides in addition to the main components. These impurities are preferably 30% by mass or less, more preferably 10% by mass or less.

  These lubricants and surfactants used in the present invention have different physical actions, and the type, amount, and combination ratio of lubricants that produce a synergistic effect are optimally determined according to the purpose. It should be done. Applying by adjusting the amount of surfactant, controlling the leaching to the surface using fatty acids with different melting points in the lower layer and cleaning layer, controlling the leaching to the surface using esters with different boiling points, melting points and polarities It is conceivable to improve the lubrication effect by increasing the amount of lubricant added in the lower layer, and of course not limited to the examples shown here. Generally, the total amount of the lubricant is selected in the range of 0.1% to 50% by mass, preferably 2% to 25% by mass with respect to the ferromagnetic powder of the cleaning layer or the nonmagnetic powder of the lower layer.

Further, all or a part of the additives used in the present invention may be added in any step of manufacturing the cleaning layer coating material or the lower layer coating material. For example, when mixed with a magnetic material before the kneading step, the ferromagnetic powder In the case of adding in a kneading step with a binder and a solvent, in the case of adding in a dispersing step, in the case of adding after dispersing, or in the case of adding just before coating. Further, the purpose may be achieved by applying a part or all of the additive simultaneously or sequentially after applying the cleaning layer according to the purpose. Further, depending on the purpose, a lubricant can be applied to the surface of the cleaning layer after calendering (heating and pressurizing with a calender roll) or after completion of the slit.
Known organic solvents can be used in the present invention, and for example, the solvents described in JP-A-6-68453 can be used.

[Layer structure]
The thickness of the cleaning tape of the present invention is such that the support is 2 to 8 μm, preferably 3 to 4 μm.
An undercoat layer may be provided between the support and the lower layer to improve adhesion. The undercoat layer thickness of the invention is 0.005 to 0.5 μm, preferably 0.01 to 0.5 μm.
In the present invention, a lower layer and a cleaning layer may be provided on one side of the support, and a back layer may be provided on the other side. The thickness of the back layer is 0.1 to 1 μm, preferably 0.3 to 0.7 μm. Known undercoat layers and back layers can be used.
The thickness of the cleaning layer of the present invention is 0.01 to 3 μm, preferably 0.05 to 0.3 μm.
The thickness of the lower layer is 0.2 μm or more and 5.0 μm or less, preferably 0.3 μm or more and 3.0 μm or less, and more preferably 0.5 μm or more and 2.5 μm or less.

[Support]
The support used in the present invention is preferably nonmagnetic. Supports include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins, cellulose triacetate, polycarbonate, polyamide (including aromatic polyamides such as aliphatic polyamide and aramid), polyimide, polyamideimide, poly Known films such as sulfone and polybenzoxazole can be used. It is preferable to use a high strength support such as polyethylene naphthalate or polyamide. If necessary, a laminated type support as shown in JP-A-3-224127 can be used to change the surface roughness of the cleaning surface and the base surface. These supports may be previously subjected to corona discharge treatment, plasma treatment, easy adhesion treatment, heat treatment, dust removal treatment, and the like.

[Production method]
The process for producing the cleaning layer coating or lower layer coating for the cleaning tape of the present invention comprises at least a kneading step, a dispersing step, and a mixing step provided before and after these steps. Each process may be divided into two or more stages. All raw materials such as ferromagnetic powder, non-magnetic powder, binder, carbon black, abrasive, antistatic agent, lubricant, and solvent used in the present invention may be added at the beginning or middle of any process. . In addition, individual raw materials may be added in two or more steps. For example, polyurethane may be divided and added in a kneading step, a dispersing step, and a mixing step for adjusting the viscosity after dispersion. In order to achieve the object of the present invention, a conventional known manufacturing technique can be used as a partial process. In the kneading step, it is preferable to use a kneading force such as an open kneader, a continuous kneader, a pressure kneader, or an extruder. When using a kneader, the magnetic powder or non-magnetic powder and all or part of the binder (however, preferably 30% by mass or more of the total binder) and 100 parts by mass of the magnetic powder are mixed in a range of 15 to 500 parts by mass It is processed. Details of these kneading processes are described in JP-A-1-106338 and JP-A-1-79274. Glass beads can be used to disperse the cleaning layer solution and the lower layer solution, but zirconia beads, titania beads, and steel beads, which are high specific gravity dispersion media, are preferred. The particle diameter and filling rate of these dispersion media are optimized. A well-known thing can be used for a disperser.

  In the present invention, when coating on a support in order to produce a cleaning tape having a multi-layer structure, the following method is preferably used. First, the lower layer is first applied by a gravure coating, roll coating, blade coating, extrusion coating device or the like generally used in the application of a magnetic paint, and the lower layer is in a wet state. JP-A-60-238179, JP-A-2-265672 discloses a method of applying a cleaning layer with a support pressure type extrusion coating apparatus, and second, JP-A-63-88080, JP-A-2-17971, -2656722, a method in which the upper and lower layers are applied almost simultaneously by a single coating head incorporating two coating liquid passage slits, and third, an extract with a backup roll disclosed in JP-A-2-174965 This is a method in which the upper and lower layers are applied almost simultaneously by means of a roux application device. In order to prevent agglomeration of the magnetic particles, it is desirable to apply shear to the coating solution inside the coating head by a method as disclosed in JP-A-62-295174 and JP-A-1-236968. Further, the viscosity of the coating solution needs to satisfy the numerical range disclosed in JP-A-3-8471. In order to realize the configuration of the present invention, it is possible to use sequential multilayer coating in which a lower layer is applied and dried and then a cleaning layer is provided thereon, and the effects of the present invention are not lost. However, in order to reduce coating defects and obtain uniform quality, it is preferable to use the above-described simultaneous multilayer coating.

  The calendering roll is preferably treated with a heat-resistant plastic roll or metal roll such as epoxy, polyimide, polyamide, polyimide amide or the like. The treatment temperature is preferably 80 ° C. or higher, more preferably 85 ° C. or higher. The linear pressure is preferably 98 kN / m (100 Kg / cm) or less, more preferably 49 kN / m (50 Kg / cm) or less.

  Hereinafter, specific examples of the present invention will be described, but the present invention should not be limited thereto. In addition, the following “parts” means “parts by mass”.

Example 1
<Creation of paint>
Coating for upper layer 100 parts of ferromagnetic metal powder Composition Fe / Co = 70/30 (atomic ratio)
Al / Fe = 11 atomic%, Y / Fe = 7 atomic%
Hc = 196 kA / m (2450 Oe), average major axis length = 0.08 μm, σs = 145 A · m ² / kg
Crystallite size = 150 Å, SBET specific surface area = 53 m ² / g
Vinyl chloride copolymer 10 parts Polyurethane resin 3 parts Carbon black 3 parts Phenylphosphonic acid 3 parts Butyl stearate 2 parts Butoxyethyl stearate 3 parts Neopentyl glycol 3 parts Stearic acid 1 part Methyl ethyl ketone 180 parts Cyclohexanone 110 parts

Lower layer paint Non-magnetic powder: α iron oxide 100 parts
BET specific surface area: 50 m ² / g
DBP oil absorption: 27-38ml / 100g
Al ₂ O ₃ is present on the surface in an amount of 1% by mass based on the whole particle. Carbon black 13 parts Vinyl chloride copolymer 17 parts Polyurethane resin 6 parts Phenylphosphonic acid 3 parts Butyl stearate 3 parts Butoxyethyl stearate 4 parts Neopentyl glycol 4 parts Oleic acid 1 part Stearic acid 1 part Methyl ethyl ketone 200 parts Cyclohexanone 50 parts

  For each of the coating materials, after kneading each component with a kneader, each of the obtained dispersions for upper layer and lower layer has a paste in which α alumina is dispersed in a vinyl chloride copolymer as the amount of α alumina. 5 parts to the dispersion for the upper layer, 13 parts to the dispersion for the lower layer, and further 40 parts of cyclohexanone to each, and filtering using a filter having an average pore diameter of 3 μm, Coating solutions for upper layer formation and lower layer formation were prepared.

<Support>
Polyamide having a thickness of 3 μm was used for the support.

The obtained lower layer coating solution is applied to one surface on the support so that the thickness after drying is 0.6 μm, and immediately after that, the thickness of the cleaning layer is 0.2 μm. Simultaneous multi-layer coating was performed and dried, and then the other backing surface was coated with a known back solution composed of carbon black powder and a binder to a thickness of 0.5 μm and dried. Thereafter, it was slit to a width of 3.8 mm, and wound around a DAT72-dedicated cassette to prepare a cleaning tape. After running a commercially available HP DAT72 tape for 24 hours using an HP DAT72 drive, the elalate is measured. Next, the error rate was measured after running the cleaning tape for 3 seconds. The bending rigidity of the cleaning tape was determined by the following measurement method.
Measuring method of bending rigidity A 180 mm tape is attached to a tensile tester, fixed at a distance of 100 mm with a jig, and a distance and a load are measured at a speed of 5 mm / min. The bending stiffness is calculated from the slope of 0.5N to 1.5N. The calculation formula is as follows.
E = [(δF / WT) / (δL / L)], I = WT 3/12
Flexural rigidity = EI
δF: Load change (N)
T: Tape thickness (mm), W: Tape width (mm)
δL / L; tape length change / original tape length E; Young's modulus (N / mm ² )

Example 2
A cleaning tape was prepared under the same conditions as in Example 1 except that the thickness of the support was changed to 3.6 μm polyethylene naphthalate, and the error rate and bending rigidity were determined.

Comparative Example 1
A cleaning tape was prepared under the same conditions as in Example 1 except that the thickness of the support was changed to 7.0 μm polyethylene terephthalate, and the error rate and bending rigidity were determined.

Comparative Example 2
A tape was prepared under the same conditions as in Example 1 except that the thickness of the support was changed to 4.4 μm polyamide, and the error rate and bending rigidity were determined. In the error rate value, for example, 2.4E-02 means 2.4 × 10 ⁻² (the same applies to others).

  From the above table, in the examples in which the bending rigidity of the cleaning tape is within the scope of the present invention, the error rate after running the cleaning tape is significantly improved in the bending rigidity range compared to comparative examples outside the present invention. I understand.

Claims (1)

A cleaning tape comprising a cleaning layer provided on one surface of a support, wherein the bending rigidity in the tape longitudinal direction is 0.0002 to 0.0004 N · mm ² .