JPS5982628A - Magnetic recording medium and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium with superior flexibility and wear resistance by using a compound contg. at least one or more activated hydrogen groups capable of reacting with an isocyanate group in the molecule. CONSTITUTION:In the manufacture of a magnetic recording medium, a magnetic coating material contg. a binder is applied to a nonmagnetic support, dried, and heat treated under irradiation with electron beams or irradiated and heat treated to cause curing by cross-linking. The binder contains 20-99.5wt% of one or more kinds of components selected from monomers, oligomers and polymers each contg. at least one or more acrylic unsatd. double bonds and contg. optionally an active hydrogen group capable of reacting with an isocyanate group in the molecule and 0-80wt% of one or more kinds of components selected from compounds, oligomers and polymers each contg. at least one or more active hydrogen groups capable of reacting with an isocyanate group in the molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium, which comprises coating a non-magnetic support with a magnetic paint and forming a magnetic layer thereon.

More specifically, the present invention features a thermosetting and radiation curable binder and a curing method thereof, which provide a magnetic recording medium with excellent coating film properties such as durability, oil resistance, and heat resistance of the magnetic layer. It is something that you have.

In recent years, there has been an increasing demand for improvements in the strength of magnetic tape coatings, and thermosetting resins such as those cured by crosslinking using polyfunctional incyanates have been used.

However, because these binders contain a high proportion of isocyanate compounds, the pot life is short, the storage stability of the paint is reduced, and surface treatment and other processes after coating must be carried out in a short period of time. . Further, crosslinking and curing requires long-time heating, which causes blocking, change in surface roughness of the back surface of the substrate, etc., and has the disadvantage that it is difficult to obtain a smooth surface of the magnetic layer.

In recent years, magnetic paints using radiation-curable resins have been proposed as a way to improve these shortcomings.4 Pot life and online curing make it possible to roll up after curing, reducing surface roughness transitions. However, many radiation-curable resins use low-molecular-weight components, and curing by short-term radiation irradiation cannot achieve sufficient molecular weight, and the coating film hardness is not good due to the high crosslinking density. However, it has been difficult to obtain a magnetic recording medium with poor flexibility and excellent wear resistance.

The present invention was developed as a result of intensive research to improve these drawbacks.
It was discovered that a magnetic recording medium with excellent coating film properties could be obtained by using the rapid curing properties of the radioactive resin and the effect of increasing the molecular weight through incyanate crosslinking, and the present invention was achieved. It is a complete product.

In other words, in one aspect, the present invention provides a magnetic recording medium in which magnetic fine powder is bonded together with a binder as a magnetic layer on a non-magnetic medium, in which the binder (1) has acrylic unsaturation in its molecules; 20-995% of monomers, oligomers and polymers containing at least one double bond and containing or not containing active hydrogen groups capable of reacting with isocyanate groups.

(2) 0 to 80% of one or more of compounds, oligomers and polymers containing at least one active water group capable of reacting with incyanate groups in the molecule; and (3) in the molecule. Incyanate compound having two or more isocyanate groups or one inocyanate group in the molecule
1. A magnetic recording medium characterized in that it is formed from a crosslinking reaction product of an isocyanate compound having one or more acrylic unsaturated double bonds and one or more acrylic unsaturated double bonds.

Another aspect of the present invention is to apply a magnetic paint mainly consisting of ferromagnetic fine powder, a binder and a solvent onto a non-magnetic support, dry it, cross-link and harden it, and then magnetically record it on the non-magnetic support. In the method for producing a magnetic recording medium, the binder (1) contains at least one acrylic unsaturated double bond in the molecule and contains an active hydrogen group capable of reacting with an isocyanate group. (2) One type of compound, oligomer, or polymer containing at least one active hydrogen that can react with an isocyanate group in the molecule; and (3) an incyanate compound having two or more incyanate groups in the molecule or one isocyanate group in the molecule.
Using a magnetic material containing 0.5 to 10% of an incyanate compound having one or more acrylic unsaturated double bonds and one or more acrylic unsaturated double bonds, coat it on a non-magnetic support, dry it, and then use an electron beam. This is a method for producing a magnetic recording medium in which irradiation and heat treatment are performed simultaneously or radiation is irradiated and then heat treatment is performed to crosslink and harden the medium.

That is, by applying a magnetic paint using the binder according to the present invention to a base material, drying it, and then irradiating it with radiation, a linear or network structure is formed by a radical reaction of acrylic unsaturated double bonds. .

On the other hand, a crosslinked structure is also formed by the reaction between active hydrogen groups and incyanate groups by heating at a predetermined temperature and at a predetermined time as required. Therefore, by combining both crosslinking and curing reactions, a high-order crosslinked structure with a high molecular weight can be obtained.
It is believed that a magnetic recording layer with excellent coating hardness and abrasion resistance can be obtained. Furthermore, the proportion of incyanate compound in the present invention may be relatively small compared to conventional thermosetting resins, and sufficient bot life can be obtained. In the curing method of the present invention, a tertiary network structure is formed by radiation curing when the heat treatment necessary for crosslinking curing with isocyanate is performed simultaneously with or after radiation irradiation. Even when heat treatment is performed, the coating film does not soften, and the surface roughness does not transfer to the surface of the magnetic layer. On the other hand, when heat treatment is first performed and then radiation irradiation is performed, the heat treatment is usually carried out by winding it into a roll, and the uncrosslinked coating film softens.
In addition to causing a change in surface roughness, the curing properties during radiation irradiation were low, and high-strength irradiation was required.

In order to eliminate such drawbacks, in the present invention, the hardening force method company,
After spreading and drying the magnetic paint, it is important to perform the heat treatment necessary for crosslinking and curing with incyanate, either simultaneously with or after the irradiation.

As the radiation-curable component in the present invention, that is, the component (1), a compound having one or more acrylic unsaturated double bonds in the molecule is used. Active hydrogen groups capable of reacting with cyanate groups, such as hydroxyl groups,
It may have a carboxyl group, an amide group, an amide group, etc.

In the present invention, the compound containing an acrylic unsaturated diM1 bond, that is, the component (1), is a compound having various reactive groups, such as a compound such as component (2). Alternatively, a compound having an acrylic unsaturated double bond group bonded to the side chain is used. Examples of compounds in which an acrylic unsaturated double bond group is bonded to the terminal or side chain of the compound include the following.

(I) 1 mol or more of a reaction product of a polyisocyanate compound and a (meth)acrylic ester monomer having a group having reactivity with inocyanate groups.

Examples include a reaction product with 1 mole of a compound having one or more hydroxyl groups in the molecule, or a reaction product obtained by changing the reaction order of these six compounds. Furthermore, by reacting with an incyanate compound in an amount smaller than the equivalent of the hydroxyl group in the oligomer or polymer, a prepolymer, oligomer, or polymer having a hydroxyl group and an acrylic unsaturated double bond can be obtained.

(11) A reaction product of one molecule of a compound containing one or more epoxy groups in the molecule and one or more molecules of a monomer having a group that reacts with the epoxy group and an O-electron beam curable unsaturated double bond. be praised.

It is known that a hydroxyl group is produced as a by-product through the reaction of an epoxy group with acrylic acid, methacrylic acid, etc., and is used as a compound having an acrylic unsaturated double bond and a Mizusaka group.

(4) Compound 1 containing one or more carboxyl groups in the molecule
Reaction product between a molecule and a group that reacts with a carboxyl group and one or more molecules of a single Ji compound having a radiation-curable unsaturated double bond 1 For example, glycidyl is added to a thermoplastic resin containing a carboxyl group obtained by solution polymerizing methacrylic acid. Examples include resins, prepolymers, and polymers in which acrylic thread double bonds are introduced into the molecule by reacting methacrylate and by opening the carboxyl group and epoxy group in the same nucleus as in item 1.

Furthermore, by reacting with a monomer having fewer epoxy groups than the equivalent of carboxyl groups in the oligomer or polymer, a prepolymer, oligomer or polymer having a carboxyl group and an acrylic unsaturated double bond can be obtained.

QV) As the monomer containing an acrylic unsaturated double bond, conventionally known monomers may be used, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, etc., and polyhydric alcohols. (Meth)acrylic acid esters such as diprolene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate can be mentioned.

Further, a compound having a group reactive with an isocyanate group and an acrylic unsaturated double bond can be obtained by esterifying a part of a polyhydric alcohol with (meth)acrylic acid. For example, trimethylolpropane di(meth)acrylate, pentaerythritol triacrylate, etc. can be mentioned.

Component (2) in the present invention is a compound containing an active water group capable of reacting with an incyanate group, such as a hydroxyl group, a carboxyl group, an amine group, or an oricomer, such as a polymer such as ADEKA polyether. P-700.
Adeka Holiether P-1000, Acrylic Ester G
-1500 (more than Asahi Denkasha 8!A), Polymeg 1000
, multifunctional polyethers such as Holimeg 650 (manufactured by Forker Kohn), IA such as nitrocellulose, acetylcellulose, and ethylcellulose! im
xh conductor, partially saponified vinyl chloride-vinyl acetate compound with hydroxyl groups such as Vinylite V AGH (manufactured by Union Carbide, USA), polyvinyl alcohol rubyral 0200, polycaprolactone PCP- Polyfunctional polyester polyols such as 0240, polycaprolactone PCP-0300 (manufactured by Chisso Corporation), saturated polybasic acids and ethylene glycols such as phthalic acid, isophthalic acid, terephthalic acid, adipic acid, succinic acid, and cepatine. ,
diethylene glycol, 1,4-butanediol, 1,
6-butanediol, 1,2-propylene glycol,
Terminal or fdil obtained by ester bonding with polyhydric alcohols such as dipropylene glycol, 1,6-hexane glycol, neopentyl glycol, glycerin, trimethylolpouvane, pentaerythritol
A saturated polyester resin having a hydroxyl group in M, an acrylic spinning wheel combination containing at least one kind of acrylic ester and methacrylic ester containing a hydroxyl group as a polymerization component, Epicor) 82B, Epicort 1001, Epicort 1007, Epicort 1009 (Shell Chemical Co., Ltd.) Other types of epoxy resins include Kusunoki Co., Ltd.) and others.

Compounds containing 1 or more carboxyl groups in the molecule include polyesters containing carboxyl groups in the molecular chain or at the end of the molecule, radically polymerizable compounds such as acrylic butylene, methacrylic acid, maleic anhydride, fumaric acid, etc. Homopolymers of monomers having carboxyl groups or copolymers with other polymerizable monomers can also be mentioned.

Further, examples of the polyisocyanate compound which is component (6) in the present invention include 2,4-toluene diisocyanate and 2,6-)toluene diisocyanate.

1, 4-xylene diisocyanate, m-phenylene diisocyanate), p-phenylene diisocyanate,
Examples include hexamethylene diisocyanate, isophorne diisocyanate, Desmodur L, Desmodur IL (manufactured by Bayer AG, West Germany), and the like.

Examples include polyurethane preformers or polymers having terminal isocyanate groups obtained by the reaction of polyols and polyisocyanates.

The component (6) may also be a compound containing an acrylic unsaturated double bond and an isocyanate group. For example, the above polyisocyanate compound may be combined with an acrylic monomer containing less hydroxyl groups than the isocyanate group. Compounds obtained by the reaction can be used.

The binder of the present invention contains a radiation-curable component (20 to 99% by weight) and a thermosetting component (2) of 0%.
~80% heavy weight, and component (6), which is a hardening agent, is 0.5
It is used in a range of 10% to 10%. If the amount of resin is less than 20%, a sufficient network structure cannot be obtained by radiation irradiation, and the system film may be softened during heat treatment. Further, the same drawback occurs even when the content of component (2) is 80% by weight or more, and a smooth magnetic layer cannot be obtained due to a change in surface roughness due to softening. When component (3) is less than 0.05% by weight, the effect of improving physical properties by heat treatment is small, and 10% by weight.
The above method has the drawback that the pot life of the paint is significantly shortened, making it difficult to handle.

In the magnetic paint of the present invention, the magnetic particles/binder (weight ratio) is appropriately used in the range of 86/14 to 65/35 from the magnetic properties and mechanical properties of the coating film formed on the material. .

A non-reactive solvent is used in the magnetic paint of the present invention. There are no particular restrictions on the solvent, but it may be translated as appropriate, taking into consideration the solubility and compatibility of the binder. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, Schiff tetrahexanone, ethyl formate, ethyl acetate,
Esters such as butyl acetate, aromatic hydrocarbons such as toluene, xylene, and ethylbenzene, ethers such as isopropyl ether, ethyl ether, and dioxane, and 7ranes such as tetrahydro-7rane and furfural are used as single solvents. It is used as a mixed solvent/agent.

The substrate to which the magnetic paint using the binder according to the present invention is coated may be those currently widely used as substrates for magnetic recording media, such as polyethylene terephthalate films, and those for applications requiring heat resistance. Polyimide film and polyamide film are used. Particularly in the case of polyester films, uniaxial stretching and biaxial stretching are often used for thin films. It still has uses for coating paper.

The magnetic fine powder used in the present invention is γ-F6203,
Fe304%, Co-doped r-Few Os,
Co-doped r-Fe103-Fe304 solid solution, CO thread compound coated r-Fe20a, C.

Thread compound-coated Fe804 (including intermediate oxidation state with γ-F6.03), the CO-based compound referred to here is:
cobalt oxide, cobalt hydroxide, cobalt 7 elite,
This shows a case where the magnetic anisotropy of cobalt, such as a cobalt ion adsorbent, is utilized to improve coercive force. Co.

Fe-Co, Fe-Co-Ni, Co-Ni
Wet reduction method using a reducing agent such as BH4 whose main component is a ferromagnetic metal such as
These are metal fine particles and single crystal barium ferrite fine powder obtained by various manufacturing methods such as a dry reduction method using H2 gas or the like, or a method obtained by vacuum evaporation in a low-pressure argon gas stream. The above-mentioned magnetic fine particles are used in the form of needles or particles, and are selected depending on the intended use as a magnetic recording medium.

In recent years, technological advances have been particularly remarkable, and the marketability of audio cassette tapes for HMFI has expanded.
For videocassette tapes, master tapes for videotape contact transfer printing, etc., the binder of the present invention and the above-mentioned magnetic fine powder contain cobalt-modified acicular oxidized iron (cobalt-doped type or cobalt-based compound) which is particularly advantageous for high-density recording applications. By combining it with acicular alloy fine particles (adhesive type) or high coercive force, it was possible to obtain a commercial tape with extremely good electromagnetic conversion characteristics and reliable physical properties.

Regarding the magnetic paint of the present invention, various commonly used antistatic agents, lubricants, dispersants, sensitizers, leveling agents, wear resistance imparting agents, paint film strength reinforcing additives, etc. may be used as necessary. I can do it. Furthermore, resins that do not contribute to the reaction can also be used if necessary.

When manufacturing a magnetic recording medium according to the present invention, such as a magnetic tape for video, for example, first, a magnetic transfer material is prepared by dispersing the binder components (1) and (2), magnetic powder, other additives, etc. in a solvent. , to which the incyanate compound of (5) is added and applied to the profiteer.
The material is heated to apply a solvent to the surface, subjected to surface treatment, and then irradiated with radiation. Then, it can be wound into a roll and heated at a predetermined temperature for a predetermined time to be cured with an isocyanate compound.

The radiation used for curing in the present invention is as follows:
Electron beams using an electron beam accelerator as a source; β-rays using CO60 as a source; β-rays using an S, @0 source; and X-rays using an X-ray generator as a source. In particular, it is advantageous to use an electron beam from an electron beam accelerator as an irradiation source from the viewpoints of controlling the absorbed dose, introducing it into the manufacturing process line, blocking ionizing radiation, etc.

As a JRI shooting rod source, electron beam accelerators are preferred in terms of absorption radiation control, self-shielding of ionizing radiation for introduction into manufacturing process lines, and ease of connection with sequence control with process line equipment. It is advantageous to use it.

Traditionally, the electron beam accelerators are Kotscroft type,
Various types of accelerators have been put into practical use, such as bump graph type, resonant transformer type, iron core insulated transformer type, and linear accelerator type, mainly due to differences in the method of obtaining high voltage.

However, most magnetic recording media for general purpose use have a thin magnetic film thickness of 10 micrometers or less, and therefore, the I o o OKV which is usually used in the above accelerator is
A higher acceleration voltage than the above is unnecessary, and an electron beam accelerator with a low acceleration voltage of 500 KV or less is sufficient. Such a low accelerating voltage accelerator is particularly advantageous not only in terms of lower costs of the system itself, but also in terms of ionizing radiation shielding equipment. The standards as shown in the table below have been reported regarding whether the shielding equipment should be made of lead or concrete and the thickness of the shielding (Report of the Radiation Utilization Research Group, p. 8, 197).
August 1999, Nippon Atomic Blade Metal 1).

As shown in the table above, at electron beam accelerator pressures of 300 KV or less, leakage of
The line can be sufficiently blocked.

For this reason, there is no need to provide a separate flat-frame electron beam irradiation room.
The irradiation system itself can be incorporated as one system in the magnetic recording medium manufacturing line, and therefore it is possible to carry out the drying and curing process of magnetic recording media using electron beams online.

Examples of such specific systems include the low-beam type electron beam accelerator (electrocurtain system) manufactured by Energy Sciences, Inc. of the United States, and the self-shielding scanning type low-am type manufactured by Hollimar Physics of West Germany. An electron beam accelerator is a suitable example.

In addition, for radiation crosslinking, N2 gas, )(e gas,
It is important to irradiate the recording medium with radiation in a stream of inert gas such as CO or gas, because coatings with a high degree of magnetic pigment filling, such as magnetic coatings, are extremely porous. Furthermore, irradiation with radiation in the air inhibits the radicals generated in the polymer from effectively working on the crosslinking reaction due to shadow rings such as zero generated by the radiation irradiation during crosslinking of the binder component.

As a result of this, the surface of the magnetic layer is naturally porous and is subject to crosslinking inhibition by the binder to the inside of the coating film.

Therefore, the atmosphere of the area to be irradiated with active energy rays is
In particular, N2 with a maximum acid ligation degree of 1%. Ne.

It is important to maintain an atmosphere of an inert gas such as CO, etc. Furthermore, the heat treatment for the crosslinking reaction 1 of the isocyanate compound in the present invention may be performed under conventionally known conditions, for example,
It is well known that heat curing is carried out at ℃ for about 24 hours.

The present invention will be specifically explained below using Examples and Comparative Examples. In addition, in winter clothing, "Part J" indicates parts by weight.

First, one synthetic example of the resin used in the present invention will be illustrated.

548 parts of tolylene diisocyanate (TDI) were heated to 80°C in a N2 stream in a four-bottle flask.
After J heat, 2-hydroxyethyl methacrylate (2HE
MA) 260 parts, tin octylate 0.07 parts and hydroquinone α 05 parts at a temperature in the reaction vessel of 80-85
Drop it while controlling the cooling so that the temperature is 8℃.
Stir at 0° C. for 3 hours to complete the reaction. After the reaction was completed, the contents were taken out, and after cooling, a white paste of TDI
2HEMA adducts were obtained.

Resin synthesis example (a) Vinyl chloride/vinyl acetate/vinyl alcohol 95/2
Copolymer 100 with molecular spots of 18,000 at a composition of 15% by weight
After heating and dissolving 1 part in 258 parts of toluene and 95 parts of cyclohexanone, the temperature was raised to 80°C, 15 parts of the following TDI adduct were added, and further 0.002 part of tin octylate and Hydroquino? Add 0,002 parts of N at 82°C.
'2 Isocyanate (NCO) reaction rate in gas stream is 90
% or more. After the reaction is completed, cool
Dilute by adding 238 parts of methyl ethyl ketone. The obtained resin composition is designated as (-). In this resin, about 55% of the hydroxyl groups in the vinyl hydrochloride resin remain unreacted.

250 parts of NIAX Polyol PC "P-0200 (Polycabrilactone manufactured by Chisso Corporation), 2-hydroxyethyl methacrylate 1 '22.2 *L Hydroquinone a0
24 parts of TDIi and 0.053 parts of octyl tin were placed in a reaction can, heated to 80°C and dissolved, and then 63.6 parts of TDIi was added dropwise while cooling so that the temperature inside the reaction can was 80 to 90°C. After the dropwise addition is completed, the reaction is allowed to proceed at 80° C. until the NCO reaction rate reaches % or more. The obtained resin composition is referred to as (b). This resin does not contain hydroxyl groups.

Resin synthesis example (C) Anhydrous 7-tal H14s, 1. 65 parts of s-butanediol,
60 parts of ethylene glycol and 2.5 parts of balatorocon sulfonic acid were placed in a reaction vessel, and heated to 150 parts under a nitrogen gas stream.
After esterification reaction at 1 hour at 180°C and 5 hours at 180°C, the mixture was cooled to 100°C, 0.6 parts of hydroquinone and 28 parts of acrylic acid were added, and esterification reaction was carried out for 15 hours. The obtained resin composition is designated as (C). This resin does not contain hydroxyl groups.

Resin Synthesis Example (d) 1174 parts of TI), 87 parts of methyl ethyl ketone and 87 parts of toluene were placed in a reaction vessel, heated to 80°C, and 155 parts of ADEKA polyether G-400 (polyether triol made by non-electrified manufacturer) was added dropwise to the reaction vessel. , reacted for 3 hours while maintaining the temperature at 80-90°C, and then added 65 parts of 2-hydroxyethyl methacrylate.

005 parts of hydroquinone α and tin octylate o,
o o s portion was added dropwise, and after completion of the dropwise addition, the reaction was allowed to proceed at 80° C. until the NCO reaction rate reached 95% or more, to obtain a compound having an isocyanate group and an acrylic unsaturated double bond. The obtained resin composition is referred to as (d).

Resin Synthesis Example (-) 10 parts of 2-hydroxyethyl methacrylate, 40 parts of butyl acrylate, 5 parts of 5Z and 575 parts of methyl isobutyl ketone were placed in a reaction vessel, and after heating to 80°C, 60 parts of 2-hydroxyethyl methacrylate was added. , 120 parts of butyl acrylate and 8 parts of penzoyl oxide as a polymerization initiator were dissolved in 112.5 parts of toluene and 1125 parts of methyl isobutyl ketone. 330
28 parts of TDI adduct and 0.0 parts of tin octylate.
0.012 parts of hydroquinone and 0.012 parts of hydroquinone at 80° C. to a Neo reaction rate of 90% or more. The obtained resin composition is designated as (e).

This #I fat contains acrylic unsaturated dil bonds and hydroxyl groups.

Ken HIi Synthesis Example (f) After heating and dissolving 200 parts of Epicote 828 (epoxy resin manufactured by Shell) in 25 parts of toluene and 25 parts of methyl ethyl ketone, 2.7 parts of N,N-dimethylbenzylamine and 1.4 parts of hydroquinone were added. The temperature was then raised to 80°C, and 69 parts of acrylic acid was added dropwise to react at 80°C until the acid value reached 5 or less. Let's call this tree 1jd (ri).

Example Cobalt coated acicular γ-Feρ3 120 parts α-AI
203 (0.5μ granules) 2 parts powder (refined soybean oil lecithin) 6 parts solvent (methyl ethyl ketone/toluene = 50150) 100 parts The above composition was premixed in a ball mill, and then) Synthesis Example (a) Resin (in terms of solid content) 18 parts Resin of Synthesis Example (b) (in terms of solid content) 12 parts of the composition were added and sufficiently dispersed in a ball mill. Then 3
A functional isocyanate compound (manufactured by Bayer AG, Desmodur L) was added in 6 parts in terms of solid content, and thoroughly mixed in a mixer to prepare a magnetic paint. Immediately apply 12μ of this paint.
It was spread on a polyester film, subjected to magnetic field orientation treatment and dry surface smoothing treatment, and then an electron beam of 160 KV (acceleration voltage) was applied to the magnetic layer for 5 times in an atmosphere of hydrogen.
Mrad irradiation was performed. Then, it was kept in a heat treatment furnace kept at 80°C for 48 hours. The obtained sample was cut into 1-inch pieces to obtain a videotape (Template 1).

Comparative Example 1 In Example 1, a paint was prepared without using the trifunctional incyanate (Desmodur L), and the resulting sample was cured under the same conditions as Example 1. A videotape (sample) was obtained by cutting it into 1 inch/inch width pieces.

Comparative Example 2 Using the magnetic paint of Example 1, it was applied onto a polyester film and subjected to dry magnetic field orientation treatment and surface smoothing treatment,
After that, the electron beam was irradiated with 5 Mrad under the same conditions as in Example 1.
Irradiated. The resulting sample was cut into a 1-inch size to obtain a FTI L videotape (Sample B).

Figure 1 shows a signal recorded on a videotape using an EIAJ unified standard open reel VTR (NY-5120 manufactured by Matsushita Electric Industrial Co., Ltd.), then a tension of 200 grams was applied to the winding side using a spring scale, and still image playback was performed. The attenuation value (steel playback) for the playback output is not shown.

As is clear from the figure, the relative speed between the magnetic coating film and the head is l.
Sample A1 exhibits significantly less signal attenuation despite severe wear conditions reaching up to 100 m/see. On the other hand, in Samples A and B, relatively good coating films were formed by electron beam curing alone, but attenuation was observed.

Figure 2 shows temperature -10℃, relative humidity 0% to 60℃, 8
After running the videotape for 5 cycles in the 0% range for 5 days (8), it was returned to room temperature, left to stand for 24 hours, and then run on the same VTR used for the still playback test to check the head drum and pinch roller. A tension analyzer model IVA-500 manufactured by Nippon Automatic Control Co., Ltd. was set up, and the change in tension on the winding side during running was plotted against the running time.

This test not only evaluates the level of the friction coefficient of the magnetic coating itself, but also makes it possible to evaluate the deterioration of tape running performance and stability against environmental conditions such as temperature and humidity.

As is clear from the figure, the change in the coefficient of friction of the tape for sample A1, which was irradiated with ecliptic radiation and then subjected to heat treatment, was small;
The running stability against changes in temperature and humidity was also good.

Example 2 P6 alloy copper-like magnetic powder 120 parts Dispersant (olein rn) 2 parts The above composition was premixed in a ball mill, and then the resin of Synthesis Example (C) (in terms of solid content) 15 parts Moisture? Saeji (higher fatty acid)
Three parts of the composition were added and thoroughly dispersed in a ball mill. Next, 10 parts L of the resin of Synthesis Example (d) was added in terms of solid content, and after thoroughly mixing with a mixer, it was immediately coated on a 12μ polyester film.
After magnetic field orientation, solvent drying, and surface smoothing treatment, an electron beam of 5 Mrad with an acceleration voltage of 160 Kv was irradiated in a nitrogen atmosphere. Then, it was held in a heat treatment furnace maintained at 80°C for 48 hours. The obtained sample was tested to 3.8 tonnage.

Example 3 In Example 2, the synthesis example (
Curing was carried out under the same conditions as in Example 2, except that 3 parts of Coronate L was added instead of d), and the obtained sample was
Cut the alloy audio cassette tape (sample 3) into M-width pieces.
) was obtained.

Comparative Example 6 Using the coating material of Example 2, it was coated on a polyester film under the same conditions and then processed and wound up into a four-ring shape. Thereafter, it was kept in a heat treatment furnace kept at 80°C for 48 hours.

Thereafter, radiation irradiation was performed under the same conditions as in Example 2 to prepare sample C.

The heat-treated sample lost its surface smoothness due to increased viscosity of the base film.

Table 1 shows the characteristics of the alloy audio cassette tape. Samples 2 and 3 have long pot lives.

Because it has excellent surface moldability after application, and because it is radiation-cured before heat treatment, it does not undergo thermal softening, resulting in extremely smooth surface properties and high residual magnetic density. Therefore, tapes with high sensitivity ranging from MOL at a low frequency of 335 Hz to a MoL at a high frequency of 16 KHl can be obtained.In contrast, in Sample C, which was heat-cured first, the surface softened during heat treatment. Smoothness was lost and sensitivity decreased.

In addition, Sample 2 exhibited better performance than Sample 3 in terms of tape running time until the tape made a squeaking sound, which is a reliable physical property of the tape, and round-trip durability running on a car stereo. This is thought to be because the incyanate component has radiation curability and thermal sandability and acts as a crosslinking agent for components (1) and (2).Example γ-F620B 120 parts carbon black ( Mitsubishi MAISOO) 5 parts α-AI203 powder (0.5μ granules) 2
(Solpitan monooleate)
3 parts of the resin of Synthesis Example (e) (in terms of solid content) 15 parts of the IN resin of Synthesis Example (f) (in terms of solid content) 15 parts of the composition (Talytotsux manufactured by DuPont) Add 3 parts of the composition and place in a ball mill. The ivy is well dispersed. Next, 3 parts of a trifunctional isocyanate compound (Desmodur L manufactured by Bayer AG) was added in terms of solid content and thoroughly mixed with a mixer to prepare a magnetic paint. This paint was immediately applied to a 188μ polyester film so that the coating layer had a thickness of about 10μ, dried, and then subjected to a surface smoothing treatment, followed by a curing treatment under the same conditions as in Example 1. The obtained sample was punched out into a disk shape (diameter 65 brocade) to obtain a magnetic disk (sample height 4).

Comparative Example 4 Curing was carried out under the same conditions as in Example 6 except that the isocyanate compound (Desmodur L) was not used. D) was obtained.

Comparative Example 5 Using the paint of Example 4, a candy cloth was coated on a polyester film and post-processing was performed under the same conditions, and the film was wound up into a roll. Thereafter, the specimen was kept in a heat treatment furnace maintained at 40° C. for 72 hours, and then subjected to electron beam irradiation under the same conditions as in Example 3.

The obtained sample was punched out into a disk shape (diameter 65 mm), and a magnetic disk (magnetic head (Pat E 40//a++"
), the vehicle was run steadily at a speed of about 1 m/sec, and the running time until 1,000 progressive dropouts were worn out was measured.

Table 2 shows the surface conditions of the obtained LC bond and magnetic layer.

Table 2 Sample 4 of the present invention has good running stability and surface condition.However, the sample 4 with electron beam irradiation M=i only has inferior wire durability. In Sample E, which was subjected to chromatography, the length of 1 Mu during running was reduced, and the visual quality was similarly reduced, suggesting that the curing properties of the radiation-curable 441 H1# were reduced.

[Brief explanation of drawings]

Figures 1-2 are graphs showing the performance of the magnetic recorder 4, UK according to the present invention. (Fig. 1, Fig. 2) Continued from page 1 0 Inventor Shigeru Shimada Tokyo Denki Kagaku Kogyo Co., Ltd., 13-1 Nihonbashi-chome, Chuo-ku, Tokyo 0 Inventor Kazunori Tamazaki Tokyo Tokyo Denki Kagaku Kogyo Co., Ltd., Tokyo Denki Kagaku Kogyo Co., Ltd., 13-1 Nihonbashi, Chuo-ku, Tokyo 0 Applicants: T-DK Co., Ltd. 1-13-1 Nihonbashi, Chuo-ku, Tokyo Procedural amendment December 20, 1980 Commissioner of the Patent Office Indication of Kazuo Wakasugi case 1981 Patent Application No. 190808 Name of the invention Relationship to the case concerning magnetic recording media and those who amend their manufacturing method Name of patent applicant Title Toyo Ink Mfg. Co., Ltd. (one other person) Agent: 103 Address Same as above 1st Supplement 1st Section Contents of the amendment subject to the amendment As shown in the attached sheet, Figure 1 of the attached drawings submitted earlier is replaced with the one attached below. Figure 1 Bamboo procedural amendment December 25, 1980 Commissioner of the Patent Office Kazuo Wakasugi Indication of the case 1981 Patent Application No. 190808 Name of the invention Magnetic recording media and the case of a person who amends the manufacturing method thereof Related patent applicant name
Toyo Ink Mfg. Co., Ltd. (1 other person) Agent - W# Consulting agent 1 inch 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 4 x 4 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 4 x 4 x 4 hours 1 x 1 x 1 x 1 x 1 x 1 x 4 day hours as a representative for Toyo Ink Mfg. Co., Ltd. - Details of the amendments to be made - Figure 1 of the attached drawings submitted earlier as shown in the attached sheet. Replace it with the one attached below.

Claims (1)

[Claims] 1. A magnetic recording medium in which magnetic fine powder is bonded together with a binder as a magnetic layer on a non-magnetic medium, wherein the binder (1) has at least one acrylic unsaturated double bond in its molecules. 20 to 995 monomers, oligomers, and polymers containing at least one active hydrogen group and containing or not containing active hydrogen groups capable of reacting with isocyanate groups.
% by weight, (2) 0 to 80% by weight of one or more of compounds, oligomers, and polymers containing at least one active hydrogen group capable of reacting with incyanate groups in the molecule; and (3) % by weight in the molecule. isocyanate compound having two or more isocyanate groups or one isocyanate group in the molecule
1. A magnetic recording medium, characterized in that it is formed from a crosslinking and curing reaction product of 0.5 to 10% by weight of an isocyanate compound having one or more acrylic unsaturated double bonds. 2. In a method for manufacturing a magnetic recording medium, in which a magnetic coating mainly consisting of ferromagnetic fine powder, a binder, and a solvent is coated on a non-magnetic support, dried, and then cross-linked and cured to form a magnetic recording layer on the non-magnetic support. - The binder is (1) one or more monomers, oligomers, and polymers containing at least one acrylic unsaturated double bond in the molecule and containing or not containing an active hydrogen group capable of reacting with an isocyanate group; (2) 0 to 80% by weight of one or more compounds, oligomers, and polymers containing at least one active hydrogen that can react with isocyanate groups in the molecule, and (3) has two or more isocyanate groups 175
A magnetic paint containing 0.5 to 10% of an isocyanate compound or an incyanate compound having one or more incyanate groups and one or more acrylic unsaturated double bonds in the molecule is used, and a non-magnetic support is used. 1. A method for producing a magnetic recording medium, which comprises coating the medium on the top, drying it, and then simultaneously subjecting it to electron beam irradiation and heat treatment or irradiating it with radiation, followed by heat treatment to crosslink and harden it.