JPS6159619A - Medium and method for magnetic recording - Google Patents

Abstract

PURPOSE:To obtain an excellent recording medium by providing a top coat layer contg. radiation curing phosphate and lubricating agent, etc. on a thin ferromagnetic metallic film consisting essentially of Co, providing a back coat contg. an inorg. pigment, etc. on the rear of a substrate and providing specific micro-projections to the surface of the medium. CONSTITUTION:The thin ferromagnetic film layer consisting essentially of Co and contg. oxygen is provided on the non-magnetic and flexible substrate and the top coat layer contg. the radiation curing phosphate, radiation curing compd., for example, glycol di(meth)acrylate, etc. and lubricating agent is provided on said film. The back coat layer contg. the inorg. pigment such as SiO2 or carbon black, binder resin and lubricating agent is provided on the opposite surface of the substrate. The projections are further formed on the medium surface at average 10<5>/a<2> pieces for each 1mm<2> when the gap length of the magnetic head to be used is designated as (a)mu in a manner as to have 30-300Angstrom height. The magnetic recording medium which has excellent running durability and electromagnetic conversion characteristic and obviates the adhesion of the tape, etc. when wound as the tape and is rested for a long period is thus obtd.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Technical Field of the Invention The present invention relates to a magnetic recording medium, particularly a fully bending 8 ng type magnetic recording medium and a magnetic recording method. Prior art and its problems As magnetic recording media for video, audio, etc., media having a metal fJ film type magnetic layer are being actively developed because of their compactness when wound into tapes. Due to its characteristics, the magnetic layer of such an eight-film type medium is made of Co-based or Co-Ni, which is formed by the so-called diagonal one-layer method, in which groove shoulders are formed at a predetermined angle of inclination with respect to the normal to the substrate. A vapor-deposited film consisting of a system or the like is suitable. Since the characteristics of such a medium are greatly degraded due to spacing loss, it is necessary to make the surface as smooth as possible. However, if you make the surface too flat, it will cause damage to the surface. la becomes large, causing problems with head touch and running surface. By the way, in a metal thin film type medium, the magnetic layer has a thickness of 0.05 to
Since it is very thin at 0.5 gm, the surface properties of the medium depend on the surface properties of the substrate. For this reason, it has been proposed to provide relatively gentle protrusions in the shape of wrinkles, worms, etc. on the surface of the base (Japanese Patent Application Laid-open No. 116115/1983, etc.). Also, JP-A-5B-68227, JP-A No. 58-10022
No. 1 proposes that fine particles be placed on the surface of a substrate to create irregularities that can be observed at 50 to 400 times magnification with an optical microscope and that can be measured using a stylus surface roughness measuring device. There is. However, even these are still unsatisfactory in terms of physical properties such as 1-s running time, running durability, and running stability, as well as electromagnetic conversion characteristics. On the other hand, Japanese Patent Publication No. 39-25246 and others propose that a top coat layer made of an organic lubricant is provided on the surface of a thin ferromagnetic metal to reduce running friction. However, when an organic lubricant is used, the lubricant adheres to the head and clogs the head, which poses a serious problem in practice. On the other hand, there is a method of providing a liquid or semi-solid lubricating layer (A-/ku coat layer) on the opposite surface of the magnetic recording layer (Japanese Patent Publication No. 5
7-29769) has been proposed. In this method, when the lubricant of the back coat W is wound on the roll, the lubricant is constantly supplied to the surface of the magnetic recording layer, which is effective in terms of durability and changes in the coefficient of dynamic friction. However, if only the lubricant is contained in the back coat layer, the lubricant in the back coat layer will be transferred to the groove shoulder film and the 11
Harm q. Then, the output becomes unstable during running, and no image is produced, and especially during reproduction with a steel moat, the film comes off and a 1g jam occurs, making it impossible to obtain a satisfactory magnetic recording medium. In addition, if the organic binder used in the top coat layer or back coat layer is thermosetting, it will not be used for the base or ferromagnetic layer in the heat treatment process! ! ! 5. There are problems such as having a large impact. That is, at present, no technology has yet been realized that reduces running friction, eliminates head adhesion and head clogging within a range that does not cause problems on the running surface, and does not cause problems in terms of electromagnetic conversion characteristics. II. Purpose of the Invention The purpose of the present invention is to improve physical properties such as friction, running durability, and running stability in a metal thin film type magnetic recording medium and a magnetic recording method using the same, and to improve physical properties such as friction, running durability, running stability, etc. The object is to eliminate head adhesion and clogging to the extent possible, and to prevent any problems from occurring in terms of electromagnetic conversion characteristics. Such objects are achieved by the invention described below. That is, the present invention provides flexibility, (a ferromagnetic total bending FJ film layer containing Co as a component is provided on the plate L, an organic top coat layer is provided on the surface of the ferromagnetic metal thin film layer, and a In a magnetic recording medium provided with a single layer of Bafukuco-1.The organic top coat layer is made of radiation-curable phosphorus ester,
The back coat layer contains a radiation curable compound and a lubricant, a mechanical pigment, an organic binder, and a lubricant. The first ferromagnetic totally refractive thin film layer contains oxygen, and furthermore, when the gap length of the CG air head is a μm, the medium surface is l
The magnetic recording medium is characterized in that it has an average of 105/a2 or more protrusions per mm2, and the protrusions have a height of 30 to 300 people. Moreover, the second invention provides G on a flexible substrate. A ferromagnetic metal thin nQ layer mainly composed of is provided, and a ferromagnetic total 7i! In a magnetic recording method in which a magnetic head is used to perform recording and reproduction on a magnetic recording medium in which an organic top coat layer is provided on the surface of the IJIIQ layer and a back coat layer is provided on the other surface, the organic top coat layer is made of radiation-curable phosphoric acid. ester,
Contains radiation-curable compounds and lubricants. The puncture coat layer contains inorganic pigments, organic pigments and lubricants. and the ferromagnetic gold a HnQ H contains Ml, and further,
A magnetic recording method characterized in that the medium surface has an average of 1o5/a2 or more protrusions per 1 mm2, and the protrusions have a height of 30 to 300 people, when the gap length of the magnetic head is &lLm. . ■Specific structure of the invention The specific structure of the present invention will be explained in detail below. The ferromagnetic metal thin film layer as the magnetic layer in the present invention is C
The main component is o, and it includes 0. Furthermore, it has a composition containing Ni and/or Cr as required. That is, in a preferred embodiment, it may consist of Co alone or it may consist of Co and Ni. When Ni is included, the weight ratio of Co/Nf is preferably 1.5 or more. Furthermore, Cr may be contained in the ferromagnetic metal thin film layer. When Cr is contained, electromagnetic conversion characteristics are improved, output and S/N ratio are improved, and 119 strength is also improved. In such cases, Cr/Co or Cr/(Co
+Ni)+7) Weight ratio is 0.001 to 0.1. More preferably, it is 0.005 to 0.05. Furthermore, O is contained in the ferromagnetic metal Al+. Average oxygen in ferromagnetic total refractive Q film 1? is the atomic ratio. In particular, the atomic ratio of O/(Co or Co+Ni) is 0.5
Hereinafter, it is more preferably 0.05 to 0.5. In this case 1 ferromagnetic 4? , on the surface of the thin Ilλ layer;
Most of them form oxides with ferromagnetic metals (Co, Ni). That is, in one surface area, particularly in a range of 50 to 500 thickness, more preferably 50 to 200 thickness from the surface, a peak indicating an oxide is observed by Auger spectroscopy. The oxygen content of this oxide layer is about 0.5 to 1.0 in terms of atomic ratio. It should be noted that such ferromagnetic metal>'
, V, Zr, Nb, Ta, Ti. Zn, Mo, W, Cu, etc. may be included. In a preferred embodiment, such a ferromagnetic total bending 8 film layer is composed of an aggregate of 11 columnar grains mainly composed of Co as described above. In this case, the thickness of the ferromagnetic metal thin film layer is 0.05 to 0.0.
The number of tiles is 5 m, preferably 0.07 to 0.3 m. The columnar crystal grains have a long width that spans almost the entire thickness direction of the thin film, and the longitudinal direction is inclined at an angle of 10 to 70 degrees with respect to the normal to the main surface of the substrate. Preferably. Note that oxygen exists in the form of a compound on the surface of the columnar crystal grains in one surface portion, as described above. Further, there is no particular restriction on the oxygen concentration gradient of the 4-ferromagnetic metal 8-layer film. Moreover, it is preferable that the short axis of the crystal grain has a length of about 50 to 500 grains. The substrate on which such a ferromagnetic metal thin film layer is formed is not particularly limited as long as it is non-magnetic, but it must be a flexible substrate, especially one made of resin such as polyester or polyimide. preferable. Moreover, its thickness may be of various thicknesses, but in particular 5.
It is preferable that the output is ~20 liters. Fine protrusions are provided at a predetermined density on the surface of the magnetic recording medium of the present invention constructed as described above. The fine protrusions are 30 to 300 people, more preferably 50 to 300 people.
It has a height of 250 people. That is, the protrusions of the present invention cannot be observed with an optical microscope and ΔIII can be determined with a stylus type surface roughness meter,
It can be observed with a scanning or transmission electron microscope. If the height of the protrusion exceeds 300 people and it can be observed with an optical microscope, the electromagnetic conversion characteristics will deteriorate and the running stability will decrease. bring. Furthermore, if the number of participants is less than 50, there is no effective improvement in physical properties. And its density is on average 105/a2 per lam2
, more preferably '1f2X 108 /a2-1X1
09/a 2 pieces. In this case, a represents the gap length of the magnetic head used in μm. and a is 0.1-0.5em, especially 0.1-0.
It is said to be 4 pots m. In addition, when the protrusion density is less than 105/a2 pieces/■2, more preferably less than 2X106/a2 pieces/mm2, physical properties deteriorate, such as increased noise, decreased still characteristics, and frequent head clogging. It is not practical. Moreover, if l 09 /a2 pieces/mm2 is exceeded, the effect on physical properties will be reduced. In order to provide such protrusions, it is usually enough to arrange fine particles on a substrate. is formed. The fine particles used are usually those known as colloidal particles, for example. 5iOz (colloidal silica), A-mon203 (alumina sol), MgO, Tio2゜ZnO, Fe203,
Zirconia, Cd01Nip, CaWO4, CaCo
3, BaCo3CoCo3, BaTi0:+, Ti
(Titanium black), Au, Ag, Cu, Ni, F
e. Various hydrosils, resin particles, etc. can be used. In this case, it is particularly preferable to use inorganic substances. Such fine particles may be prepared by forming a coating liquid using various solvents, applying this to a substrate and drying it, or by applying a coating liquid containing a resin component such as various aqueous emulsions and drying it. Good too. Note that, in some cases, protrusions may be provided by adding fine particles to the tomp coat layer instead of disposing these coating liquids on the substrate. Furthermore, when vA fat is used, it is possible to superimpose the fine protrusions based on these fine particles and submerge the gentle protrusions, but this is usually not necessary. In addition, 2II plate and ferromagnetic metal thin 11! If necessary, various known underlayers may be interposed between the JWI and the JWI. Furthermore, if necessary, the ferromagnetic metal thin film layer may be divided into a plurality of parts, and a non-ferromagnetic metal 'r', U film layer may be interposed in 1 m of the divided parts. In the present invention, the magnetic layer is formed by electrolytic vaporization. Although ion blasting, plating, etc. can also be used, it is preferable to form by a so-called oblique vapor deposition method. In this case, relative to the substrate normal. The minimum value of the incident angle of the vapor deposition substance is preferably 200 or more. When the incident angle is less than 20°, electromagnetic conversion characteristics deteriorate. The deposition atmosphere is usually argon or helicopter. The atmosphere was set to an inert atmosphere such as a ram or vacuum, containing oxygen gas, and the pressure was 101 to 100 Paa degrees, and the deposition distance, substrate conveyance direction, structure and arrangement of the can and mask were the same as known conditions. Bye. Then, by vapor deposition in an oxygen atmosphere, a fully curved oxide film is formed on the surface. Note that the oxygen gas partial pressure at which the total diluted product is formed can be easily determined through experiments. Note that various oxidation treatments can be performed to form IIQ of gold H oxide on the surface. Applicable oxidation treatments include the following. l) Dry process a, energetic particle process As described in Japanese Patent Application No. 76,640/1982, oxygen is applied to the magnetic layer as energetic particles using an ion gun or a neutral gun in the latter stage of vapor deposition. b, Glow treatment 02, N20, 02 +H20Qp and Ar. An inert gas such as N2 is used to generate plasma by glow discharge, and the surface of the magnetic film is exposed to this plasma. C.Oxidizing gasThings that spray oxidizing gas such as ozone or heated steam. d, Heat treatment: Oxidation is performed by heating, heating temperature is 60-15
Around 0℃. 2) Wet treatment a, anodizing, Flukali treatment C1 acid treatment, chromate treatment, permanganate treatment. Use phosphorous salt treatment, etc. d. Using oxidizing agent treatment H2O2, etc. Conventionally, when only a lubricant is applied to the top coat layer, only a temporary reduction in seat friction can be achieved. Vj Since it is significantly inferior in terms of rust resistance, corrosion resistance, and durability,
As a technical means to solve these problems, the present invention provides a specific top coat layer. The top coat layer of the present invention contains a radiation-curable compound, a radiation-curable phosphate ester, and a lubricant. The radiation-curable compounds used in the top coat layer of the present invention include acrylic acid, methacrylic acid, or acrylic double bonds such as ester compounds thereof, diallyl phthalate, etc., which have unsaturated double bonds that exhibit radical polymerizability. Use resins that contain or introduce into the thermoplastic resin molecules groups that can be crosslinked or polymerized and dried by radiation irradiation, such as allylic double bonds such as allylic double bonds, maleic acid derivatives, etc., and unsaturated bonds such as maleic acid derivatives. I can do it. Other usable polymer components include: Examples of monomers include acrylic acid, methacrylic acid, and acrylamide. As polymers having double bonds, various polyesters, polyols, polyurethanes, etc. can be modified with compounds that have positive acryl bonds. Furthermore, by blending a polyhydric alcohol and a polyhydric carboxylic acid as necessary, products with various molecular weights can be produced. The above-mentioned radiation-sensitive resins are some of them, and these can also be used in combination. In addition, (A) a plastic-like compound having two or more unsaturated double bonds that is curable by radiation or having a molecular weight of 5,000 to 100,000 that is not curable by radiation; (B) a non-plastic compound that is curable by radiation; 1 saturated double bond
rubber-like compound having 13,000 to 100,000 molecules or having no radiation curability, and (
C) A compound having one or more unsaturated double bonds that is curable by radiation and having a molecular layer of 200 to 3,000.
These may be used alone or in the form of a mixture, and in the case of a mixture, particularly preferred are (A) 20 to 70% by weight, (E) 20 to aQffi %, and (C) 10 to 40% by weight. This is the combination used. In addition, the number of unsaturated double bonds in the compounds (A), (B), and (C) is 2 or more, preferably 5 or more for (A'), and 1 or more for (B), preferably 5 or more per molecule. , (C) is 1 or more, preferably 3 or more. The plastic-like compound (A) used in the present invention is one that generates radicals by radiation and produces a crosslinked structure.
Contains two or more unsaturated double bonds in the molecular chain,
It can also be obtained by radiation-sensitizing modification of thermoplastics. Specific examples of radiation-curable resin fingers include acrylic double bonds such as acrylic acid, methacrylic acid, or their ester compounds, which exhibit radically polymerizable unsaturated double bonds, and 7, such as diallyl phthalate. Groups that can be crosslinked or polymerized and dried by radiation irradiation, such as lylic bivalent bonds, maleic butylene, and unsaturated bonds such as maleic m derivatives,
It is a resin contained or introduced into the molecule of a thermoplastic resin. Other compounds with unsaturated double bonds that undergo cross-linking polymerization when irradiated with radiation and have a molecular weight of 5,000 to 10,000.
0, preferably 10,000 to aooooo can be used. Examples of resins containing groups in the molecule of thermoplastic resins that can be crosslinked or polymerized and dried by radiation irradiation include primary unsaturated polyester resins. A polyester compound containing a radiation-curable unsaturated double bond in its molecular chain, for example, a saturated polyester resin consisting of an ester bond of a polybasic acid and a polyhydric alcohol as shown in (2) below, where part of the polybasic acid is maleic acid. Examples include unsaturated polyester resins containing a radiation-curable asymmetric bond. Radiation curable unsaturated polyester resin is a multi-I! Maleic acid, fumaric acid, etc. are added to one or more base acid components and one or more polyhydric alcohol components, and dehydration or dealcoholization is carried out in a conventional manner, that is, in the presence of a catalyst, at 180 to 200°C in a nitrogen atmosphere. After that, the temperature was raised to 240-280°C. It can be obtained by a 1 m reaction under reduced pressure of 0.5 to 1 mmHg. The content of maleic acid, fumaric acid, etc. in the acid component is 1 to 40 mol%, preferably 10 to 30 mol%, in view of crosslinking and radiation curability during production. Examples of thermoplastic resins that can be modified into radiation-curable resins include the following. (1) Vinyl chloride copolymer Vinyl chloride-vinyl acetate-vinyl alcohol copolymer, Ii! Vinyl vinyl alcohol copolymer, vinyl chloride-vinyl alcohol-vinyl propionate copolymer, vinyl chloride-vinyl acetate-maleic acid co-ffi combination, vinyl chloride-vinyl acetate vinyl alcohol-maleic acid copolymer, 1 ! Vinyl divinyl acetate-vinyl acetate-terminated OH side chain alkyl copolymer, such as VROH, VYNC, VYBGX, VERR, VYES, VMCA, VAGH manufactured by UCC, etc., by the method described below.
Radiation sensitivity modification is performed by introducing acrylic double bonds, maleic double bonds, and allylic double bonds. (2) Saturated polyester resin A mild polyhydric octacid such as phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, and sebacic acid, and ethylene glycol, diethylene glycol, glycerin, trimethylolpropane, 1.2 propylene glycol,
1.3 Butanediol, dipropylene glycol, l. A saturated polyester tree 11 obtained by ester bonding with a polyhydric alcohol such as 4-butanediol, 1.6-hexanediol, pentaerythritol, sorbitol, glycerin, neopentyl glycol, 1,4-cyclohequinane dimethanol, or These polyester resins are modified with SO3Na etc. (for example, Pylon 5
3S) is given as an example, and these are also subjected to radiation sensitivity modification in the same manner. (3) Polyvinyl alcohol resin A copolymer of polyvinyl alcohol, butyral resin, art-tar resin, formal resin, and these lano components, and the hydroxyl groups contained in these resins are subjected to radiation-sensitivity modification using the method described below. . (4) Epoxy resin, phenoxy resin Epoxy resin 1 produced by the reaction of bisphenol A, epichlorohydrin, and methyl epichlorohydrin For example, Shell Chemical (Epicort 152.154, 828.1001° 1004.1007), Dow Chemical (DEN431)
, DER732, DER511, DER331), Dainippon Ink tA (Evicron 400.800), and the above-mentioned epoxy high polymerization resin Phenokine resin CPKHA, PKHC, PKHH) manufactured by UCC, a combination of brominated bisphenol A and epichlorohydrin. polymer,
Manufactured by Dainippon Ink and Chemicals (Ebikuron 145.152,
153.1120), and these also include those containing a carboxylic acid group. These 4! Radiation sensitivity modification is performed using the Epoquine group contained in fat I. (5) Various cellulose derivatives are used, but the particularly effective ones are nitrified cotton, cellulose acetobutyrate, ethyl cellulose,
Butyl cellulose, acetyl cellulose, etc. are suitable. By utilizing the hydroxyl groups in the resin? Radiation sensitivity degeneration is performed by the method described in &. Other resins that can be used for radiation sensitivity modification include polyfunctional polyester resins, polyether ester resins, polyvinylpyrrolidone resins, and derivatives (P
Also effective are acrylic resins containing at least one of VP olefin copolymers), polyamide resins, polyimide resins, phenolic resins, spiroacetal resins, acrylic esters and methacrylic esters containing hydroxyl groups as polymerization components. The compound of polymer 9 of CB) used in the present invention is a thermoplastic elastomer or prepolymer, or a radiation-sensitive modified version of these, and the latter is more effective. Examples of elastomers or prepolymers are listed below. (1) The use of polyurethane etestomer or prepolymer polyurethane improves abrasion resistance and the base film,
For example, it is particularly effective in terms of good adhesion to PET film. Examples of urethane compounds include incyanate,
2.4-toluene diisocyanate, 2.6-) toluene diisocyanate, 1゜3-xylene diisocyanate, ■, 4-xylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p- phenylene diisocyanate, 3,3'-dimethyl-4,42-diphenylmethane diisocyanate,
4.4'-diphenylmethane diisocyanate, 3.
3'-dimethylhyphenylene diisocyanate, 4.
Various polyvalent incyanates such as 4'-biphenylene diisocyanate, hexamethylene diisone 7ate, isophorone diisonanate, dicyclohexylmethane diisocyanate, Desmodur L, Desmodur N, and a-type saturated polyesters (ethylene glycol, diethylene glycol, glycerin) , trimethylolpropane, 1,4-butanediol, 1,6-hexanediol, pentaerythritol, sorbitol, neopentyl glycol, 1,4-cyclohexane dimetatool, and phthalic acid, isophthalic acid. , terephthalic acid (by polymerization with mild polybasic acids such as succinic acid, adipic acid, sepacic acid), linear saturated polyethers (polyethylene glycol, polypropylene glycol, polytetramethylene glycol) and caprolactam, hydroxyl-containing acrylics. Polyurethane elastomers and prepolymers made of condensation products of various polyesters such as acid esters and hydroxyl-containing methacrylic esters are effective. By reacting the terminal incyanate group or hydroxyl group of these urethane elastomers with a monolayer containing acrylic double bonds or allylic double bonds,
Modification to radiosensitivity is very effective. It also includes those containing OH, COOH, etc. as a polar group at the end. (2) Acrylonitrile-butadiene copolymer elastomer Commercially available as PolyBD Reit Resin manufactured by Sinclair Petrochemical. An acrylonitrile butadiene copolymer prepolymer with a terminal hydroxyl group or an elastomer such as Hiker 1432J manufactured by Roki Zeon Co., Ltd. is particularly suitable as the elastomer component in which the double bond in the butadiene generates radicals by radiation and is used to form the bridge 4a and the polymer. . (3) Polybutadiene elastomer A prepolymer having a low molecular weight terminal water a group, such as PolyBD Ritainoresin R-15 manufactured by Sinclair Petrochemical Co., is particularly suitable in terms of compatibility with thermoplastic resins. Since the R-15 prepolymer has a hydroxyl group at the end of one molecule, it is possible to increase radiation sensitivity by adding an acrylic unsteady double bond to the end of the molecule, making it even more advantageous as a binder. Become. In addition, polybutadiene cyclized product, Nippon Synthetic Rubber CER
-M901 also has excellent properties due to its combination with thermoplastic resin. Other suitable thermoplastic elastomer and prepolymer systems include styrene-butadiene rubber, 11! rubber, acrylic rubber, in-prene rubber, and their cyclized products (ClR701 manufactured by Nippon Synthetic Rubber Co., Ltd.), as well as elastomers such as epoxy-modified rubber and internally plasticized saturated linear polyester (Toyobo Vylon #300), which are radiation-sensitive modified as described below. It can be used effectively by processing it. Examples of the compound (C) having a radiation-curable dislocated double bond used in the present invention include styrene, ethyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate (diethylene glycol diacrylate), and 1,6-hexane glycol diacrylate. Acrylate, 1,6-hexane glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, polyfunctional hepta-oligoester acrylate (Aronix M-7100, M-5400
, 5500, 5700, etc., manufactured by Toagosei), urethane elastoms with -(dineborane 4040) acrylic modified products, and those into which functional groups such as cooH are introduced. Next, an example of radiation-curable polymer synthesis will be explained. a) Synthesis of acrylic modified vinyl chloride vinyl acetate copolymer resin (radiation-sensitive modified resin) 750 parts of partially saponified vinyl chloride-vinyl acetate copolymer (average degree of integrity n=500) containing OH groups and toluene. 1,250 parts of cyclohexanone and 500M of cyclohexanone were placed in a 4-hole flask (No. 51) and dissolved by heating. After raising the temperature to 80°C, 61.4 parts of 2-hydroxyethyl methacrylate adduct* of tolylene diisocyanate was added, and further 0.012 parts of tin octylate and 0.012 parts of hydroquinone were added, followed by NGO reaction at 80°C in a N2 stream. The reaction was allowed to occur until the reaction rate reached 90%. After the reaction is completed, the mixture is cooled and diluted with 1250 parts of methyl ethyl ketone.

[Preparation of 2-hydroxyethyl methacrylate (2HHMA) adduct of 0.07 part, hydroquinone 0.05
After completing the dropwise addition while controlling the cooling so that the temperature inside the reaction vessel is 80-85°C, stir at 80°C for 3 hours to complete one reaction. A paste-like TDI 2HEMA was obtained. b) Synthesis of acrylic modified butyral resin (radiation-sensitive modified resin) 5100 parts of butyral resin BM-5 manufactured by Sekisui Chemical Co., Ltd. was mixed with 191.2 parts of toluene and 71.4 parts of cyclohexanone.
4 of them were placed in a flask, heated and dissolved, and after raising the temperature to 80°C, 7.4 parts of TDI's 2HEMA adduct* was added, followed by 0.015 parts of tin octylate, and 0.0 parts of l\hydroquinone.
015 parts was added, and the NCo reaction rate in a N2 stream at ao°C was 9.
The reaction is allowed to occur until it reaches 0% or more. After the reaction is completed, it is cooled and diluted with methyl ethyl ketone. C) Synthesis of acrylic modified ffi polyester resin (
Radiation-sensitive modified resin) Saturated polyester resin (Toyobo Vylon RV-200
) was heated and dissolved in 116 parts of Tojlz-W7 and 116 parts of methyl ethyl ketone, and after raising the temperature to 80°C, 3.55 parts of TDI's 2HEMA adduct * was added, 0.007 part of tin octylate, and 0.007 part of hydroquinone. Add
80"C-t' React until the NGO reaction rate in the N2 air stream reaches 90% or more. d) Synthesis of acrylic modified epoxy resin (radiation-sensitive modified resin) Epoxy resin (Epicoat 1007 manufactured by Shell Chemical Co., Ltd.) 40
After heating and dissolving 0 part in 50 parts of toluene and 50 parts of methyl ethyl ketone, N,N-dimethylbenzylamine o,oos
1, and 0.003 parts of hydroquinone, the temperature was raised to 80°C, 69 parts of acrylic acid was added dropwise, and the mixture was allowed to react at 80°C until the acid value reached 5 or less. ii) Synthesis of acrylic modified phenoxy resin (radiation-sensitive modified resin) Phenoxy resin having an OH group (PKHH: manufactured by UCC, molecular weight 30,000) 80 (lit), 1,800 parts of methyl ethyl ketone was charged into 4 flasks of 31, heated and dissolved, After raising the temperature to 80°C, 6.0 parts of 2-hydroxyethyl methacrylate adduct of tolylene diisocyanate was added, and further 0.012 parts of octyltin and 0.012 parts of hydroquinone were added, followed by NGO reaction in a N2 stream at 80°C. The molecular weight of this phenoxy modified product is 35000. There is one double bond per molecule. e) Synthesis of acrylic modified urethane elastomer (radiation curable elastomer) 250 parts of cyanate diphenylmethane diisocyanate (MDI) based urethane prebomer (Nipporan 3119 manufactured by Nippon Polyurethane), 2HHMA32.
Part 5. Hydroquinone 0.071. Tin octylate 0.009
After heating and dissolving at 80°C, the TDI was 43.
5 parts were added dropwise while cooling the reaction vessel to a temperature of 80 to 90°C, and after the dropping was completed, the reaction rate was 95 at 80°C.
% or more. f) Synthesis of acrylic modified polyether-terminated urethane-modified elastomer (radiation-curable elastomer) Polyether PTG-50025 manufactured by Nippon Polyurethane Co., Ltd.
0 parts, 2HEMA 32.5 parts, hydroquinone 0.07
and 0.009 parts of tin octylate into a reaction vessel, and
After heating and dissolving at °C, 43.5 parts of TDI was added dropwise while cooling the reaction vessel to a temperature of 80 to 90 °C.
After completing the above steps, the reaction is allowed to proceed at 80° C. until the reaction rate reaches 95% or more. g) Synthesis of acrylic modified polybutadiene elastomer (radiation curable elastomer) Low molecular weight terminal hydroxyl group polybutadiene PolyBD Liquid Resin R-15250 parts manufactured by Nunkle 7 Petrochemical Co., Ltd., 32.5 parts of 2HHMA, 0.007 parts of hydroquinone , tin octylate 0.0
Pour 09 parts into a reaction vessel, heat and melt at 80°C, and then add TDI4
3.5 parts are added dropwise while cooling the reaction vessel to a temperature of 80 to 90°C, and after the completion of a reaction, the reaction is allowed to occur until the reaction rate reaches 95% or more. It is known that there are those that disintegrate when exposed to radiation and those that cause intermolecular crosslinking.Those that cause intermolecular crosslinking include polyethylene, polypropylene, polystyrene, polyacrylic ester,
polyacrylamide, polyvinyl chloride, polyester,
These include polyvinylpyrrolidone rubber, polyvinyl alcohol, and polyacrolein. East 41ff like this! If it is a polymer, the crosslinking reaction will occur even without the above modification.
In addition to the above-mentioned modified products, these resins can be used as they are as top coat resins for radiation crosslinking. Furthermore, according to this method, even a solvent-free resin that does not use a solvent can be cured in a short time, so such a resin can be used for coating. In addition, the functional groups include alcohol-based, phenol-based, phosphorus-based tricarboxylic acid groups, aromatic,
Also included are those containing fatty acid groups, sulfonic acid groups, amine groups, ammonium groups, etc. In particular, those having functional groups have better density than ferromagnetic &9112. Particularly preferred radiation-curable resin compositions of the present invention include a vinyl chloride-vinyl acetate copolymer into which a carboxylic acid is introduced, in which the compound (A) is partially saponified;
Polyisocyanate compound in vinyl chloride-vinyl acetate-hinyl alcohol-maleic copolymer, epoxy, phenoxy resin (preferably one into which carboxylic acid such as phthalic acid, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, etc. is introduced) This is a compound obtained by reacting a compound having an incyanate group obtained by reacting with an acrylic compound or a methacrylic compound having a functional group that is reactive with the incyanate group. The compound (E) is an incyanate compound or polyol (polyurethane elastomer, preferably 0H1) obtained by reacting a polyol with an incyanate compound.
It is a compound obtained by reacting an acrylic compound or a methacrylic compound having a monoreactive functional group with CoOHJli (in which CoOHJli has been introduced), and (C) is a polyfunctional (meth)acrylate monomer, an oligoester acrylate,
Or (B) is a low molecular weight compound. Combinations of these are also included. By using a radiation-curable polymer, it has good adhesion to the ferromagnetic side 11g, and the top coat layer is reinforced by the polymer, increasing the breaking strength of the coating film, strengthening the coating film, and preventing top coat abrasion. It is possible to improve durability during high-temperature running. Therefore, it is possible to obtain a magnetic recording medium that has uniform characteristics in the length direction, with little dropout, and no curling during curing when wound into a roll. Without polymer, there will be a stop at high temperature running, there will be a lot of abrasion, and there will be adhesion. Further, when a radiation-curable polymer is used, continuous processing is possible in manufacturing the top coat layer, and processing can be performed online, which is useful for energy saving and cost reduction. The radiation-curable phosphoric acid ester used in the top coat W of the present invention contains an alkyl group as R in the ester moiety, a buenyl group in the alkino group, low oxidized ethylene, and propylene oxide, and the R is preferably C1 to C26. , more preferably 1 to 22), NH
There are four types of acrylic and vinyl types that are sensitive to ionization energy. It is a phosphoric acid ester having a maleic double bond. Phosphate esters include mono-, di-, and tri-type phosphoric acid esters, and may have a large mono- or di-component content, and tri-type phosphoric acid esters may be cut. Examples of these phosphate esters include (2-hydroxyethyl) methacrylate phosphate, butyl hydroxy methacrylate phosphate, capryl hydroxy methacrylate phosphate, myristyl hydroxy methacrylate phosphate, stearyl hydroxy methacrylate phosphate, cetyl hydroxy methacrylate phosphate, butylphenyl hydroxy methacrylate phosphate, amyl phenyl Hydroxy meccrylate phosphate,/nylphenyl hydroxy methacrylate phosphate, and acrylate types of these may be mentioned. When using these radiation-curable phosphate esters,
Continuous processing is possible in manufacturing the top coat layer, and processing can be done online, which helps save energy and reduce costs. The coating film is uniform and the RA-resistant film adheres well, which is an excellent effect. Examples of lubricants used in the present invention include silicone oil,
Fluorine oil, fatty acids, fatty acid esters, paraffin,
Liquid paraffin. Although surfactants etc. can be used, fatty acids and/or
Alternatively, it is preferable to use a fatty acid ester. Examples of fatty acids include fatty acids with 12 or more carbon atoms (RCo
Oh. R is an alkyl group having 11 or more carbon atoms), and fatty acid esters include fatty acid esters consisting of -144 fatty acids having 12 to 16 carbon atoms and monohydric alcohols having 3 to 12 carbon atoms, and 17 carbon atoms. A fatty acid ester or the like is used, which is composed of -Jn'-based infantile fatty acid fatty acid having at least three carbon atoms and a monohydric alcohol having a total of 21 to 23 carbon atoms. As the silicone, those made of fatty acid-modified silicones and those partially fluorine-modified are used. The alcohol used is one made of higher alcohol, and the fluorine used is one obtained by electrolytic substitution, telomerization, oligomerization, etc. Among the lubricants, it is also advantageous to use radiation-curable types. These are ferromagnetic tIILj! Since the transfer to the back mold 2 is suppressed, it has advantages such as preventing dropout, reducing output differences depending on the inner and outer diameters when wound into a roll, and enabling online manufacturing. Examples of radiation-curable lubricants include compounds having a molecular chain exhibiting lubricity and an acrylic double bond in the molecule, such as acrylic esters, methacrylic esters, vinyl acetate esters, acrylic amide compounds, vinyl alcohol esters, Includes methyl vinyl alcohol ester, allyl alcohol ester, glyceride, etc. These lubricants are expressed in the following formula: CH2=CHCoOR1 CH3 CH2=C-GOORl CH2=CH-CH2GOOR. CH2=CHC0NHCH20CoR. CR20CoCH= CR2, HOCoR ■ CH20CoR RCoOC) (=CH2. CH3 Honey RCoOC=CH2. RCoOCH2-CH=CH2 etc., where R is a straight chain or branched saturated or unsaturated hydrocarbon group, and the number of carbon atoms is is 7 or more, preferably 12 or more and 23 or less, and these can also be fluorine-substituted products. As fluorine-substituted products, Cn F2n+1-1CnF2r, , (CH2) m
- (however, m=1 to 5), CnF2rl+, S02 NCH2CH2-. cnF2n, lCH2CH2NHCH2CH2-. Examples include CnFh, 0-O-CoOCH2CH2-, and the like. Preferred specific examples of these radiation-curing lubricants include:
Examples include stearic acid methacrylate (acrylate), stearyl alcohol methacrylate (acrylate), glycerin methacrylate (acrylate), glycol methacrylate (acrylate), silicone methacrylate (acrylate), vinyl stearate, vinyl myristate, and the like. The proportions of the radiation-curable polymer, radiation-curable phosphate ester, and lubricant in the top coat layer of the present invention are as follows:
Radiation-curable polymer diphosphate ester = lO: 90~
90:10, preferably 30:70-70:3
0 parts by weight, lubricant is polymer + phosphate ester xoo
, 1. ; 0.5 to 30 parts by weight. In addition to the above-mentioned additives, it is also possible to use brewing inhibitors other than commonly used phosphate esters. To provide a top coat layer containing a radiation-curable compound, a radiation-curable phosphate ester, and a lubricant on the surface of a ferromagnetic thin film, the additives described in iii. Alternatively, first, a radiation-curable polymer or a radiation-curable phosphate ester is coated, and after curing, the lubricant is coated or vapor-deposited on the coated film. A vapor deposited film can be formed. The No. 1111 additive can be applied using a solvent. In addition, in the vapor deposition of the additive, the additive is vaporized in the atmosphere, in an inert gas, or in a vacuum, and the vapor is
This is done by applying it to the surface of the substance on which the film is to be formed. When the additive is vapor-deposited, the surface of the film becomes uniform and a good output waveform can be obtained. The thickness of the top coat layer is preferably 10-100 mm; if it is too thick, the electrical properties may deteriorate or scratches may occur. Also, if it is too thin, clogging will occur. A particularly preferable range is 10 to 50 people. The back coat layer of the present invention contains an inorganic pigment, an organic binder, and a lubricant. Inorganic pigments include 1) conductive carbon black and graphite, and 2) Si as an inorganic filler.
o2.7i02, AlI303, Cr203, Si
C, Cab, CaCo3, zinc oxide, goethite, αF
e2O3, talc, kaolin, CaSO3, boron nitride,
There are black salt fluorides, molybdenum disulfide, ZnS, etc., among them CaC0:+, kaolin ZnO, and goethite. ZnS and carbon are used. The amount of such inorganic pigment used is 20 to 200 parts by weight per 100 parts by weight of the binder for 1), and 2)
10 to 300 parts by weight is appropriate; however, if the amount of inorganic pigment is too large, the coating becomes brittle and there is a disadvantage that the amount of do + and pull-out increases. As a lubricant (including a dispersant), any of the types conventionally used for this type of back coat layer can be used, but caprylic acid, capric acid, lauric acid,
Fatty acids with 12 or more carbon atoms (RCoOH
, R is an alkyl group having 11 or more carbon atoms); Metal soaps made of alkali gold B (Li, Na, etc.) or alkaline earth metals (Mg, Ca, Ba, etc.) of the fatty acids; Lecithin, etc. are used. Ru. In addition, higher alcohols having 12 or more carbon atoms, sulfuric esters thereof, surfactants, titanium coupling agents, silane coupling agents, etc. can also be used. These lubricants (dispersants) are added in an amount of 1 to 20 parts by weight per 100 parts by weight of the binder. In addition to the above, lubricants include silicone oil, graphite, molybdenum disulfide, tungsten disulfide, and fatty acid esters consisting of monobasic fatty acids with 12 to 16 carbon atoms and monohydric alcohols with 3 to 12 carbon atoms. , carbon fi1
A fatty acid ester or the like is used, which is composed of seven or more monobasic fatty acids and a monohydric alcohol having 21 to 23 carbon atoms in total, including the total number of carbon atoms in the fatty acid. These lubricants are added in an amount of 0.2 to 20 fi parts based on 10011 ri parts of the binder. In addition, as other additives, any additives used in this type of back coat can be used; for example,
Natural surfactants such as saponin as antistatic agents; 7-ion surfactants such as fullkylene oxide, glycerin, and glycidol; higher alkylamines,
Quaternary ammonium salts, pyridine and other heterocycles,
Cationic surfactants such as phosphonyl or sulfonyl; anionic surfactants containing ugly groups such as carboxylate, sulfonic acid, phosphoric acid, sulfate ester groups, phosphate ester groups, Niamino m class, 7mi/sulfo/# class , amphoteric activators such as sulfuric acid or phosphoric acid esters of alcohols, etc., are used. As the organic binder used in the back coat layer of the present invention, thermoplastic, thermosetting or reactive resins conventionally used for magnetic recording medium, or mixtures thereof, are used.
can get? From the viewpoint of li strength, etc., curable resins, particularly radiation curable resins, are preferred. The thermoplastic resin has a temperature of 150"C or less,
Average molecular weight is io, ooo~200. 000, with a degree of polymerization of about 200 to 2.000, 1
For example, vinyl chloride-vinyl acetate copolymer (including those with carboxylic acid introduced), vinyl chloride-vinyl acetate-vinyl alcohol copolymer (including those with carboxylic acid introduced)
, vinyl chloride-vinylidene 114 co-hybrid, 11X
Vinyl chloride = 7 Acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, nistyl acrylate-vinylidene chloride copolymer, acrylic ester-styrene copolymer, methacrylic ester-acrylonitrile copolymer, methacrylic butyester- Vinylidene 141 copolymer, methacrylic acid ester-styrene copolymer, urethane etestomer, nylon-silicon resin, nitrocellulose-polyamide resin, polyvinyl 7onide, vinylidene chloride-acrylonitrile copolymer, butadiene-7-krylo Nitrile copolymer, polyamide resin,
Polyvinyl butyral, cellulose derivatives (cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin, chlorovinyl ether-acrylic acid ester copolymer, amino resin, Various synthetic rubber-based thermoplastic resins and mixtures thereof are used. As a thermosetting resin or a reactive resin, in the state of a coating liquid, it is 200%
．． It has a molecular weight of 000 or less, and when heated after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. Moreover, among these resins, those that do not soften or melt until the resin is thermally decomposed are preferable. Specifically, examples include phenol resins, epoxy resins, polyurethane curable resins, urea resins, melamine resins, alkyd resins, silicone resins, acrylic resins, acrylic reaction resins, epoxy-polyamide resins, nitrocellulose melamine resins, and high molecular weight polyesters. Mixtures of resins and incyanate prepolymers, mixtures of methacrylate copolymers and diisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea-formaldehyde resins, low molecular weight glycols/high molecular weight diols/triphenylmethanthoifcyanate mixtures, polyamine resins, and mixtures thereof. Preferred examples include mta* resin (nitrified cotton, etc.), vinyl chloride-vinyl acetate-vinyl alcohol copolymer, thermosetting resin made of a combination of urethane (using a curing agent), or vinyl chloride-vinyl acetate-vinyl alcohol. It is made of a radiation-curable resin consisting of a copolymer (including those with carboxylic acid introduced) or an acrylic modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer (including those with carboxylic acid introduced) and urethane acrylate. In addition to the above-mentioned preferred combinations, radiation-curable resins include acrylic double bonds such as acrylic acid, methacrylic acid, or ester compounds thereof, which exhibit radically polymerizable unsaturated double bonds, and diallylphthalate. It is possible to use resins that contain or introduce into the molecule of thermoplastic resin groups that are crosslinked or weight-dry by radiation irradiation, such as allylic double bonds and unsaturated bonds such as maleic acid and maleic acid derivatives. can. Other binder components that can be used include acrylic acid, methacrylic acid, acrylamide, and the like. As binders with double bonds, various polyesters, polyols, polyurethanes, etc. can be modified with compounds having acrylic double bonds. Furthermore, by blending a polyhydric alcohol and a polyhydric carboxylic acid as necessary, a material having a molecular weight similar to that of the heel can be produced. The above-mentioned radiation-sensitive resins are some of them, and these can also be used in combination. More preferable is (A) 5 molecular weight s,oo having two or more unsaturated double bonds that are curable by radiation.
o ~ 100,000 plastic-like compound, (B) one molecule having one or more unsaturated double bonds that is curable by radiation or not curable by radiation, +ii:
3. Rubber-like compounds of OOO~too, ooo, and (fly) compounds with one molecule of H6,200~3.000 having one or more unsaturated double bonds that are curable by radiation, (A) 20~ 70% by weight, (B) 20~
This is a combination used at a ratio of 80% weight and Magnetic recording with uniform characteristics in the length direction, with little dropout because there is no transfer of inorganic filler powder from the coating layer to the magnetic layer, and no curling during curing when wound into a roll. In manufacturing the magnetic recording medium of the present invention, if the organic binder is a thermosetting type, the surface of the lubricant in the puncture coat layer is transferred to the magnetic thin film during the manufacturing process, resulting in unstable running as described above. This is undesirable as output town may occur due to the image being no longer produced, or the friction level may still be greatly insufficient and the ferromagnetic film may be removed or destroyed due to surface transfer. , Therefore,
It may be possible to apply a top coat first, but this is often inconvenient as it is easily damaged during operation. Furthermore, in the case of thermosetting rolls, the difference in electromagnetic conversion characteristics between the inside and outside of the jumbo roll during thermosetting becomes a problem because of the back-side transition of the eight coated surface due to curling during curing. On the other hand, in the case of radiation-curable resins, continuous curing is possible due to manufacturing, the curing time is 1σ shorter, and there is no back mold transfer as described in Radiation curing and top coat processing can be done online, which helps to save energy and reduce the number of manpower required during manufacturing, leading to lower costs. In terms of characteristics, in addition to dropouts caused by the tightness of the magnetic tape during thermosetting, there is no difference in output due to the lengthwise distance of the magnetic tape due to differences in pressure at the inner and outer diameters when it is wound into a roll. . In the radiation-curable resin binder consisting of Fl [1. (A), (B) and (C), (A) alone is inflexible and brittle, (B) alone lacks elasticity, and (A) ), CB) can increase the fracture energy, but there is a limit to increasing the brittle energy, and (A) and CB) alone have low hardness, so it is difficult to stick to them under high temperature and humidity. This resulted in increased static friction. On the other hand, in addition to (A) and (B), (C
), the crosslinkability increases, the tensile strength, breaking energy, and brittle energy of the binder increase, and a tough coating film with a high degree of curing is obtained without chipping of the puncture coat. Therefore, when stored at a high temperature of 50°0.80% for 5 days, no adhesion occurred, the coefficient of friction was low, and no image distortion occurred. This is because the addition of (C) increased the crosslinking properties of the back coat film and increased the degree of curing. By further adding (C) to (A) and (B), in the case of a composition consisting only of (A) and (B), the ratio becomes
Component (A) can now be used even if it has a low molecular weight. This is because by introducing component (C) into a plastic-like product made of component (A), the plasticity is improved and the degree of curing is improved, resulting in a coating film with high brittle energy that is viscoelastic. It is something. In the radiation curable resin binder of the present invention, (A)
Molecular weight of (B) less than 5,000, molecular weight of (B) 3.500
If it is less than that, the paint film will become hard and the back coat will be scratched.
Electromagnetic conversion characteristics also deteriorate. Moreover, if the molecules of (B) exceed ytoo, ooo, the electromagnetic conversion characteristics will deteriorate due to poor dispersion, and (B)
If the material is radiation curable, its properties are degraded, resulting in a decrease in strength. Regarding (fly), when the molecular weight exceeds 3,000, the crosslinkability decreases and the strength of the coating film decreases. (A) is to, 000~ao, ooo, (B) is 3.
000~ao, ooo, (C) is 200'~2.50
The preferred molecular layer range is 0, and (B) is preferably radiation-curable because it increases crosslinking properties and increases coating film strength. The blending ratio of (A), (B), and (C:) is (A
) is 20 to 70% by weight, preferably 30 to 79% by weight, (
B) is 20-80% by weight, preferably 20-60% by weight, (C) is 10-40% by weight, preferably 10-
It is 30 weight Q%. The molecular weights of the compounds (A), (B), and (C) of the present invention are determined by the number average molecular weight determined by the following measuring method. Average molecular weight of binder by GPC Al11 Constant GP
C (Gel Permeation Chloe+a
tograph) is a method of separating molecules in a sample based on their size in a mobile phase, and is a method of performing liquid chromatography by filling a column with a porous gel that acts as a molecular sieve. To calculate the average molecular weight, use polystyrene of known molecular weight as a standard sample and create a calibration curve from its elution time. From this, polystyrene t! ! ! Calculate the average molecular weight of Assuming that there are Ni molecules of 1 molecular weight Mi in a given high molecular weight substance, it is expressed as follows. The number of unsaturated double bonds in the compounds (A), (B), and (G) of the present invention is 2 or more (A) per molecule;
Preferably 5 or more, CB) is 1 or more, preferably 5 or more, and (C) is 1 or more, preferably 3 or more. When the organic binder in the back coat layer of the present invention is a radiation-curable type, the same radiation-curable polymer as used in the topcoat layer is used, and the type and combination of the resin composition, manufacturing method, etc. All the examples given in the section of the coat layer can also be applied to the back coat layer. It is known that some polymers disintegrate when irradiated with radiation, while others cause crosslinking between molecules. Examples of substances that cause crosslinking between molecules include polyethylene, polypropylene, polystyrene, polyacrylic ester,
polyacrylamide, polyvinyl chloride, polyester,
These include polyvinylpyrrolidone rubber, polyvinyl alcohol, and polyacrolein. With such crosslinked polymers, the crosslinking reaction occurs even without the above-mentioned modification, so in addition to the modified products mentioned above, these resins can be used as they are as backcoat resins for radiation crosslinking. be. Furthermore, according to this method, even a solvent-free resin that does not use a solvent can be cured in a short time, so such a resin can be used as a back coat. Particularly preferable combinations of the radiation-curable binder composition of the present invention include vinyl chloride-vinyl acetate copolymer in which the compound (A) is partially saponified, and vinyl chloride-vinyl butyrate in which carboxyl alcohol is introduced. A copolymer or phenoxy resin is reacted with a polyisocyanate compound (a compound having an isone anate group is reacted with an acrylic compound or a methacrylic compound having a functional group that is reactive with J or ti). The compound CB) is obtained by reacting a polyol with an incyanate compound, and is obtained by reacting an incyanate compound or polyol (polyurethane elastomer) with an acrylic compound or methacrylic compound having a reactive functional group. (C) is a polyfunctional (meth)acrylate monomer, oligoester acrylate, or a low molecular weight compound of (B). In addition, crosslinking of the radiation-curable polymer in the top coat layer of the present invention, an organic binder used in the back coat layer, and fill contained in the top coat layer or back coat layer.
Active energy rays used for crosslinking when the lubricant and antioxidant are of radiation curing type include electron beams using a radiation accelerator as a source, γ-rays using Co60 as a source, S
β-rays using r90 as a radiation source, x using an X-ray generator as a radiation source 1. , or ultraviolet rays are used. In particular, as an irradiation source, a method of using radiation using a radiation heater is advantageous from the viewpoints of controlling the absorbed dose, requiring four people to enter the manufacturing process line, and shielding ionizing radiation. The radiation characteristics used when curing the above-mentioned back coat layer and top coat layer are as follows. In terms of penetration power, the accelerating voltage is 100 to 750 KeV. It is convenient to use a radiation accelerator, preferably 150 to 300 KaV, and to irradiate at an absorbed dose of 0.5 to 20 megarads. For the radiation curing of the present invention, a low-dose type radiation accelerator (Electro Curtain System) manufactured by Energy Sciences, Inc. in the United States is used for introducing into the tape coating processing line and shielding secondary X-rays inside the accelerator. Extremely advantageous. Of course, a van de Graaf accelerator, which has been widely used as a radiation accelerating material, may also be used. In addition, during radiation crosslinking, it is important to irradiate the back coat layer and top coat layer with radiation in an inert gas stream such as N2 gas or He scum. When crosslinking, radicals generated in the polymer due to the effects of 03 and the like generated by radiation irradiation are extremely disadvantageous because they inhibit the crosslinking reaction. Therefore, the atmosphere in the area to be irradiated with active energy rays should be particularly composed of N2, He, C, etc., where the oxygen concentration is at most 5%.
It is important to maintain an inert gas atmosphere such as O2. The top coat layer of the present invention can also be cured with ultraviolet light by adding a photopolymerization sensitizer. As the photopolymerization sensitizer, conventionally known ones may be used, such as benzoin methyl ether, benzoin ethyl ether, α-methylhenzoin, α-chlordeoxybenzoin, etc., benzophenone, acetophenone, bisdialkylaminobenzoin, etc. Examples include ketones such as pheno-7, quinones such as anthraquinone and phenanthraquinone, and sulfite iA such as benzyl disulfide and tetramethylthiuram monosulfide. The photopolymerization sensitizer is preferably used in an amount of 0.1 to 10% by weight based on the resin solid content. When manufacturing RJ11A recording media, when forming a thermosetting backcoat surface, if the backcoat surface is formed before the magnetic surface, the thermosetting treatment of the backcoat surface will reduce the surface roughness of the base surface because of the tightness of the base. Therefore, heat curing treatment was performed after forming the magnetic surface. Therefore, back coating treatment is normally performed on the back side of the support after forming a magnetic coating film on the support, but when the radiation curable binder is used in the present invention, the back coat treatment is performed on the back side of the support. It is possible to obtain a high-performance tape that has no tight winding and has extremely good electromagnetic conversion characteristics and reliable physical properties. ■Specific effects of the invention In the present invention, the top coat layer is reinforced by containing the above-mentioned radiation-curable polymer and is less likely to be scratched, and by containing the radiation-curable phosphate ester, the top coat layer is reinforced. The rust effect is significant, and by including a lubricant, the scratch resistance on the surface of the magnetic layer is reduced. Therefore, a magnetic recording medium with excellent running stability and magnetic properties and reduced dropout can be obtained. Furthermore, since a back coat layer is also provided, the riverside effect is enhanced. Since this backcoat layer contains an inorganic pigment, an organic binder, and a lubricant, the breaking strength of the coating film increases, the coating film becomes strong, and backcoat abrasion is reduced. In addition, the amount of inorganic filler powder from the back coat layer to the magnetic layer is
Because there is no rolling, there are fewer dropouts, and
A magnetic recording medium having uniform characteristics in the length direction is obtained without curling which occurs during a thermal effect process when wound into a roll. Additionally, if the polymers and resins used in the top coat and back coat layers are radiation-curable, manufacturing
Continuous curing is possible, it can be processed online, the curing time is short, and there is no so-called TA type transfer, so dropouts can be prevented. According to the present invention, since the surface of the magnetic layer has protrusions of a predetermined size and a predetermined density, running friction becomes extremely small and stabilized. In addition, the running durability is significantly improved, there is no increase in running friction even after many runs, the number of repeat recordings and playbacks is significantly improved, and the still characteristics are significantly improved. It also has high running stability, exhibiting extremely high stability under a wide range of conditions, from high temperature and humidity to low temperature and low humidity. Furthermore, the reproduction output due to spacing loss is also extremely small. Also, noise is extremely low. In addition, head clogging and head adhesion are extremely rare. Such effects are even higher when a metal ferromagnetic head is used. Further, such an effect becomes even higher in high-density recording where the lowest recording wave rj: is less than l Rulo. V Specific Examples of the Invention Examples of the invention are shown below. Example 1 Colloidal silica was coated on a smooth polyester film (thickness: 12 μm) substantially free of fine particles to obtain a substrate having microprotrusions. The height of the protrusions is approximately 150, and the density of protrusions is approximately 107/+i+
(1) Formation of magnetic layer 1 x 1 x 1 x The above substrate was moved along the circumferential surface of a cylindrical cooling can, and 02+Ar (volume ratio 1:l) was applied at a speed of 800 cc per minute. Co 80. An alloy made of Ni2O is melted. Oblique evaporation is performed only on the part with an incident angle of 90° to 30°, I+!
2 A Co-Ni-0 thin film with a thickness of 0.15 μm was formed. A large amount of oxygen was unevenly distributed at the interface with the base and on the surface opposite to the base. Furthermore, the surface opposite to the base was covered only with oxide. Hc=1000 0e. The average amount of oxygen in the film was 40% with an atomic ratio of Co to Ni (-X 100 ) oNi.The above substrate was moved along the circumference of a cylindrical cooling can, and the vacuum The vapor deposition was carried out in the same manner as in the case of "Tada Wataru Yukusei" in a chamber with 5 and OX I O' Torr. 1
The thickness is 0.15 μm and is substantially made of Co—Ni. This tape was forcibly fermented in an atmosphere of 90° C. and 20% RH, so that only the oxide was formed on the surface opposite to the base. Hc=9000e, the average amount of oxygen in IIA is Co
The atomic ratio to N1 was 45%. [January] Same as the 1st W except that the oxidation process with oxygen was omitted.
The above substrate was moved along the circumferential surface of the cylindrical cooling canopy, and the degree of vacuum was increased to 5.0 O.
X I Chaff at 0-6 Torr /<-. The vapor deposition was carried out in the same manner as in the case of 1. 11bt, had a thickness of 0.15 μm and was substantially made of Co—Ni. Hc=9500e. (2) Formation of top coat layer Top coat 1 Part by weight Butyl (2) Hydroxy methacrylate phosphate (mixture of mono- and di) Acrylic modified chloride, vinegar, vinyl alcohol (containing maleic acid) copolymer Molecular weight: 20,000 F/ Marital stearic acid silicone 0.4MEK
The above top coat composition was applied to 100% ferromagnetic thin film 11, and 150KeV, 60%
It was irradiated at mA, 3 Mrad, in N2 gas to form a top coat with a thickness of 11 mm and 20 mm. and Mumu Tsuji” double fiX part ethyl (
3) Hydroxy methacrylate phosphate (mixture of mono, di, and tri) epoxy modified product (contains succinic acid) Molecular weight 6000 1 Stearic acid 0.5 Stearic acid modified silicone 0.5 Toluene/ethanol (9/l) 1 OO ferromagnetic thin A top coat layer was formed in a vague manner similar to the above top coat 1. There were 30 people in one camp. Part by weight stearyl (2) hydroxy acrylate phosphate (mono,
(mixture of di) 3-fluorocarbonoxy modified product, molecular weight 30,000
0.6 Acrylic modified polyurethane elastomer molecular weight 4°000 0.6 Polyfunctional acrylate Molecular weight 500 0.8 Stearin acrylate IMEK/l toluene (
1/l) 100 ferromagnetic thin film was coated with the above top coat composition, and heated at 150 KeV, 10oA,
5 Mrad in N2 gas! ! I'! ! ? t L
, 11 thick, 40 people's top coat. -L-7'Ethyl ether by weight Nonylphenyl (1) Hydroxy methacrylate phosphate amine (mixture of mono and di) 2 Ultraviolet curing epoxy resin (7 Deca Ultraset) B6136J) 1 Hennin ethyl ether ■MEK/ ) Luene (+/l)' 100 Coat the above top coat Ml on the ferromagnetic thin film, and heat it with an ultraviolet lamp (output 8).
Light QJL at a line speed of 30 m/min under 0W/effective weight 1 cIl). The top coat was 1 coat thick and 40 coats thick. -L! -ヱ≦shi=-) 5 Parts by weight Nonylphenyl (2) Hydroxy methacrylate phosphate amine (mixture of mono and di) Ultraviolet curing epoxy resin (7 Deca Ultraset) B6138J) 1.5 Unmodified salt vinyl acetate (chlorinated vinyl vinegar Containing beemaleic acid) 0.5 Polyfunctional acrylate 0.5 Hesiphenone 2MEK/) Luene (1/l) 100 Ferromagnetic thin strips were coated with one top coat layer in the same manner as in Top Coat 4 above. The film thickness was 40 people. 11H Lm A Butyl (2) hydroquine methacrylate phosphate 1 Epoxy modified product Molecular weight 80000 0.5 Acrylic modified polyurethane elastomer Molecular weight 5000
0.5 Polyfunctional acrylate molecule J1500 0,2 MEK to. The above At-coated ferromagnetic thin film was heated at 150 KeV and 6 m.
A, 3 Mrad, irradiated in N2 gas. Then add B stearyl methacrylate 0.3 fluorine oil (telomerization method) 0.2 MEK to soil A. The composition of l 50KeV, 4mA, 2
It was irradiated in Mrad and N2 gas to form a top coat with a film thickness of 20. Stearyl alcohol was adsorbed on soil of composition A of Top Co-16 provided on ferromagnetic EV 11!2 in a vacuum system. There were 15 people on the 11th grade. -L Yu" L Unini L" On top of the composition A of the top coat 6 provided on the ferromagnetic thin film,
Fluorine oil was adsorbed in a vacuum system. The film thickness was 15 people. Top coats 1, 2, and 3 are obtained by removing the radiation-curable compound from the compositions of top coats 1, 2, and 3, and increasing the amount of phosphorous ester by the amount removed. (3) Formation of back coat layer/Hakecoat °1 (thermosetting type) Part by weight Zinc butyride 80m Hiro 200 Hardening agent Coronate L 20Dm agent Stearic acid modified silicone 4 Butyl stearate
2 Nitrified cotton 4° Vinyl chloride-vinyl alcohol copolymer (Made by Block Chemical Co., Ltd., S-LEC A) 30 Boliu J Tan Elastomer 30 (B, l'/'-/manufactured by Tritch Co., Ltd.,
Erasene 5703) mixed solvent (M, IBK/toluene)
250 stops two two two stops J”
Part by weight Carbon black 5° Manufactured by Asahi Carbon Co., Ltd. LOOm (A) Acrylic modified 111 bimonoacetic acid and vinyl alcohol copolymer Molecular weight 45.000 50 (B) Acrylic modified polyurethane elastomer molecule q 5000
50 stearic acid
2 stearin butyl
2 mixed solvent (MIBK/toluene-1/I)
300 The above mixture was dispersed in a ball mill for 5 hours. It was applied to the back side of the polyester film on which the magnetic surface was formed so that it had a dry thickness of 1, and was applied using an electrocurtain type electron beam front apparatus at an acceleration voltage of 150 KeV, an electrode current of 10 mA, and an absorption line of Q 5 Mrad, N 2 The back coat layer was irradiated with an electron beam in a gas atmosphere. Bark coat ・3 Parts by weight Zinc sulfide #L diameter variable 30 Carbon black 25 Acrylic modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer (molecular weight 3
10,000) 40 acrylic modified polyurethane elastomer molecules!
7120 ,000 40 polyfunctional acrylate molecule jil 1000 20 oleic acid
4. Stearin methacrylate 2. Mixed solvent (MIBK/)
(Luene) 250 These were processed and manufactured in the same manner as back coat layer 2. 8. Kukote 4 ffI presentation part C
aCo380mg 50 Acrylic modified vinyl chloride monoacetate vinyl alcohol copolymer Molecular weight 3
0.000 30 Acrylic modified polyurethane lastomer molecular weight 50.000 30
Acrylic modified phenoxy resin molecular weight 35.000 20 Polyfunctional acrylate Molecular weight 500 20 Stearin Ugly
4 Solvent (MEK/Toluene-
1/l) 300 Process these as above, 51! I left it behind. These ferromagnetic materials +; M II di and topcoat II
The media shown in Table 1 were prepared using Q. The characteristics are shown below. The magnetic head used is shown in Figure Ef'51, with a gap f of 0.25 gm and a track length of 204 mm.
It belongs to m. In this case, the core halves 21 and 22 are made of ferrite, and the end face of the cap is made of Co0.8 with a thickness of 30 mm formed by sputtering. NiO river, Zr0.
1 (atomic ratio), and the gap material was glass. In addition, a ferrite magnetic head was used for comparison. In addition, 105/a2 is 1.6X10". The method for measuring the above characteristics is described below. 1. Using protrusion observation SEM (scanning electron microscope) and TEM (transmission electron W4 imitation mirror) 2. , still characteristics 5 MIX, and the still characteristics of the playback output are A11l.
Set. 10 minutes or more is considered an OK level. 3. Friction measurement on the magnetic side Wrap the magnetic tape so that it is on the cylinder side, apply a load of 20g to one end, and measure the friction by reading the change in tension when the cylinder is rotated 90'. 4. Shows the S/N ratio (relative value) when recording and reproducing at an output center frequency of 5 MHz, and evaluated its stability. VH3+7) Modify the VTR so that it can measure 5MHz. 5. Clogging VH5+7) Using VTR Day/+, clogging was measured after running 100 times. 6. Head Adhesion After a predetermined number of running tests, the head drum was removed and the contact surface with the tape was observed using an optical microscope. 7. Guide adhesion After a predetermined number of running tests, adhesion to the guide pins was observed using an optical microscope. 8. Top coat scraping The tape after running test for a predetermined number of times was measured by observation using an optical microscope. Example 2 The relationship between the height and density of protrusions on the surface of the magnetic film and the characteristics is shown in the following table. Note that the experiment was conducted using a signal with the shortest recording wavelength of 0.7 Bm. The amorphous head and ferrite head of Example 1 were used as magnetic heads. Further, the top coat was used in Example 1, the top coat layer 2 was used, the magnetic film manufacturing conditions were used in Example 1, 1, and the back coat was used in Example 1, 2. 1 50 2XLO6 Amorphous 0
None 2 50 5X107 Same as above +0.2 Elementary 3
100 4XlO [1 same as above +0.1 Small 4 10
0 5X107 Same as above Q p5 100 2
X108 Same as above -0.2 small 6 200 3X105
Same as above O None 7 Zoo 4X107 Same as above -0,1 None 8 200 3X108 Same as above +0.
1 Small 9 300 2X106 Same as above -0,1 Small 10 300 3X107 Same as above -0,2 Small II
300 3X108 Same as above -0.3 small 12 -
- Same as above O large 131000 3X106 Same as above - 0.9 large + 4
ioo 105 Same as above -1,0 out of +5 10
0 4X106 Ferrite -2,0 out of 18
200 4X109 Same as above -2,1 out of 1? 30
0 2XlOg Same as above -2.1 in 181000 3
X108 Same as above -11.0 Large Further, as a result of Auger spectroscopic analysis, it was found that the surfaces of these magnetic layers were covered with an oxide layer of 100 to 200 people. In addition, in the above-mentioned example, as inorganic fine particles. Although colloidal silicate force was used, it goes without saying that other materials such as aluminium, titanium blank, zirconia, or various hydrosils may also be used. Note that similar results were obtained when a head made of Co-Fe-Ru-Cr-5i-B-based amorphous material was used. Furthermore, when a head made using sendust was used, the effect was less than in the above case.

[Brief explanation of the drawing]

FIG. 1 is a front view showing one example of a magnetic head used in the present invention. ■...Magnetic head 21.22...Core half-dead 31.32...Metal ferromagnetic material 4...Cap

Claims (12)

[Claims] (1) Magnetic recording in which a ferromagnetic metal thin film layer containing Co as a main component is provided on a flexible substrate, an organic top coat layer is provided on the surface of the ferromagnetic metal thin film layer, and a back coat layer is provided on the other surface. In the medium, the organic top coat layer is made of radiation-curable phosphate ester,
The back coat layer contains an inorganic pigment, an organic binder, and a lubricant, the ferromagnetic metal thin film layer contains oxygen, and the magnetic head has a gap length of a μm. When,
A magnetic recording medium characterized in that the medium surface has an average of 10^5/a^2 or more protrusions per 1 mm^2, and the protrusions have a height of 30 to 300 Å. (2) The flexible substrate is made of polymer, and on this substrate,
Arranging fine particles having a diameter of 30 to 300 Å,
The magnetic recording medium according to claim 1, further comprising a ferromagnetic metal thin film layer and an organic top coat layer. (3) The magnetic recording medium according to claim 1 or 2, wherein the ferromagnetic metal thin film has a ferromagnetic metal oxide layer on its surface. (4) The magnetic recording medium according to any one of claims 1 to 3, wherein the top coat layer contains a radiation-curable lubricant. (5) The magnetic recording medium according to any one of claims 1 to 4, wherein the top coat layer has a thickness of 10 to 100 Å. (6) The magnetic recording medium according to any one of claims 1 to 5, wherein the organic binder of the back coat layer is a radiation-curable resin. (7) The organic binder of the back coat layer is (A) a plastic-like compound with a molecular weight of 5,000 to 100,000 having two or more unsaturated double bonds that is curable by radiation; (B) a plastic-like compound that is curable by radiation. A rubber-like compound with a molecular weight of 3,000 to 100,000 that has one or more unsaturated double bonds or does not have radiation curability; and (C) a rubbery compound that has an unsaturated double bond that is curable by radiation. 9. The magnetic recording medium according to claim 1, which is a resin composition comprising one or more compounds having a molecular weight of 200 to 3,000. (8) The magnetic recording medium according to any one of claims 1 to 6, wherein a is 0.1 to 0.5 μm. (9) Magnetic recording in which a ferromagnetic metal thin film layer containing Co as a main component is provided on a flexible substrate, an organic top coat layer is provided on the surface of the ferromagnetic metal thin film layer, and a back coat layer is provided on the other surface. In a magnetic recording method in which recording and reproduction are performed on a medium using a magnetic head, the organic top coat layer is made of radiation-curable phosphate ester,
It contains a radiation-curable compound and a lubricant, the back coat layer contains an inorganic pigment, an organic binder, and a lubricant, and the ferromagnetic metal thin film layer contains oxygen, and the gap length of the magnetic head is a μm. When,
A magnetic recording method characterized in that the medium surface has an average of 10^5/a^2 or more protrusions per 1 mm^2, and the protrusions have a height of 30 to 300 Å. (10) The magnetic recording method according to claim 9, wherein at least the end face of the gap portion of the magnetic head is made of a metal ferromagnetic material. (11) The magnetic recording method according to claim 9 or 10, wherein the metal ferromagnetic material is an amorphous magnetic alloy containing Co as a main component. (12) The magnetic recording method according to any one of claims 9 to 11, wherein a is 0.1 to 0.5 μm.