JPS60133529A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To form a magnetic layer on an intermediate layer and to obtain a recording medium having a good winding style and excellent S/N, etc. by providing an intermediate layer which contains polyether having plural (meth)acryloyl groups in one molecule and is polymerized and cured by radiations on a nonmagnetic base having specific surface roughness and forming a magnetic layer on the intermediate layer. CONSTITUTION:An intermediate layer contg. polyether having >=2 acryloyl groups or methacryloyl groups in one molecule is formed on a nonmagnetic base having >=0.01mu surface roughness by coating the soln. of such polyether on the base and irradiating UV rays, electron rays, etc. thereto after drying then polymerizing and curing the layer. The intermediate layer is formed to <=0.01mu surface roughness. The intermediate layer having said roughness or below is easily obtd. by using the above-described polyther. A magnetic layer by vapor deposition, etc. of the thin magnetic metallic film or a coating method of magnetic powder and a binder is then provided on the intermediate layer. The magnetic tape having good runnability, good winding style and excellent S/N and C/N is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium suitable for high-density recording.

[Prior art]

In magnetic recording media for high-density recording, which has been developed in recent years, it is necessary to improve the surface properties of the magnetic layer in order to reduce the so-called gap loss between the magnetic head and the magnetic tape. be done. For this purpose, the manufacturing technology of the magnetic layer, i.e. the branching of magnetic particles, the application,
It is necessary to improve the surface properties of the magnetic layer by improving surface molding techniques, and it is also necessary to improve the surface properties of the support. In particular, as the recording density increases and the recording wavelength decreases, attempts have been made to make the magnetic layer thinner in order to avoid thickness loss. As a result, the influence of the surface properties of the support on the surface properties of the magnetic layer is becoming increasingly large.

However, there are limits to improving the surface properties of supports used in magnetic recording media for the following reasons. In other words, in the manufacturing and winding process, if the surface of the film is good, the frictional resistance against the conveyance roller will be large, often causing meandering or wrinkles. Furthermore, the friction resistance between the films increases and the shape of the take-up roll may become distorted.

Various attempts have been made to solve the above-mentioned contradictory problems Ii and 1J. For example, special 'B
Publication No. 1096059/1983 describes a method in which fine particles of a thermoplastic resin are made to protrude on a support, and after being wound up, the resin is dissolved and removed using a solvent during the formation of a magnetic layer.

However, this method not only requires a step of dissolving and removing, but also does not provide satisfactory characteristics as a magnetic recording medium for high-density recording.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording medium suitable for high-density recording, which eliminates the drawbacks of the prior art described above.

Another object of the present invention is a magnetic recording medium with excellent S/N or C/N? It is about providing.

Still another object of the present invention is to provide a magnetic recording medium having an intermediate layer having high adhesion to a nonmagnetic support.

Another object of the present invention is to provide a magnetic recording medium having an intermediate layer with excellent coating suitability.

Still another object of the present invention is to provide a durable magnetic recording medium.

[Structure of the invention]

In order to achieve the above object, the present inventors investigated the surface roughness (Ra) of 0.01μ? ? z (cutoff 02ptin) A polyether containing two or more acrytetrayl groups or methacryloyl groups (hereinafter referred to as polyether acrylate) in the molecule is used between the nonmagnetic support and the magnetic layer. ], and by providing an intermediate layer that is polymerized and hardened by radiation irradiation, the above objectives are achieved and significant effects are obtained. The present invention was based on this discovery.

That is, in the present invention, an intermediate film containing polyether acrylate is provided between a nonmagnetic support having a surface roughness of 0.01μ772 or more and a magnetic layer, and the intermediate layer M is a group 1
This is a magnetic recording medium having four characteristics: 1jJ'Aik 6.

Furthermore, particularly in the magnetic recording medium of the present invention, it is preferable that the surface roughness of the intermediate layer is 0.0111 m or less.

The present invention will be explained in detail below.

It is possible to use different surface roughness for the front and back sides of the non-magnetic support used in the present invention, but advanced techniques are required to manufacture UL and G of such supports. However, manufacturing efficiency is also low. Therefore, the present invention is mainly applied to a support whose front and back surfaces are prepared to have substantially the same surface roughness, but the scope of the present invention is not limited to this.

Supports used in the present invention include polyester f4 such as polyethylene terephthalate and polyethylene-2,6-naphthalate; polyolefins such as polyethylene and polypropylene; cellulose tri-heptate, cellulose di-heptate, cellulose acetate butyrate, Heptalulose-conducting conductors such as silulose acetate probionate; vinyl resins such as polyvinyl chloride and polyvinylidene chloride; plastics such as polycarbonate, polyimide, and polyamideimide, as well as aluminum, copper, tin, zinc, or Non-magnetic metals such as non-magnetic alloys and non-rusting copper; paper coated or laminated with lA1 baryta or a-polyolefins having 2 to 10 carbon atoms such as polyethylene, polypropylene, and ethylene-butene copolymers; etc.

The surface roughness referred to in this invention is JIS-BO601
The centerline average roughness r defined in Section 5, the cutoff value is 0.25111 m.

The surface roughness of the support that can be used in the present invention is 0.01 μm
Above, especially 0.015μ? It is preferable that it is n~0.5μnl.

A so-called back layer can be provided on the back surface of the support for the purpose of improving running properties and the like. In this case, the surface roughness of the back layer is 0.01 μm or more, preferably 0.01 μm or more.
By setting the thickness to 5 μm or more, the effects of the present invention can be similarly obtained.

The polyether acrylate used in the intermediate layer of the present invention is obtained by modifying the 2a or more hydroxyl groups of the polyether polyol with acrylate-1 by Mq%+'+ combination of polyhydric alcohol or ring-opening polymerization of algylene oxide. Or it is methacrylate modified.

Polyhydric alcohol, ethylene glycol, propylene glycol, butanediol, bentanediol,
Neopentyl glycol, hexanediol, octanediol, cyclohexanediol, cyclohexane 1
Examples include 4-dimethatol, diethylene glycol, triethylene glycol, chrycerin, trimethylolpropane, pentaneerythritol, dibentaneerythritol, and the like.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, and compounds obtained by modifying polyether polyols with acroyl or methacroyl, such as alkyl-substituted oxides of these oxides.

The polyether acrylate used in the present invention! The preferred molecular weight of '1 is 300 or more, more preferably 1,500 or more and 5,000 or less.

According to the present invention, when polyether acrylate is provided on a support and subjected to uncontrolled irradiation to polymerize and harden it to form an intermediate layer, an intermediate layer with good adhesion to the support is formed, and Even when using a support with a surface roughness of 0.01 μm or more (such surface roughness is preferable for winding operations during film formation), the surface roughness is good (
For example, the surface roughness is 0.01μ? n or less) can form an intermediate layer, and therefore the magnetic iJE formed on C1
You can improve the phantom surface quality in 9 ways. Also, according to the present invention, if fffJ )';
The coating properties of the coating layer have also been improved, and this works in conjunction with the surface properties mentioned above.
Violation of durability, 4. - It is possible to obtain a magnetic recording medium suitable for Takayuki 1 Uaki f'hi.

The intermediate unit of the present invention may contain vinyl chloride, if necessary.
Vinylidene chloride resin, urethane 415J resin, acrylonitrile butene, vinyl chloride
Vinegar 1T#Vinyl copolymer, jf, Wi Qj [, heat r of base resin, acecool resin, etc. It can be used with urethane acrylates.

The radiation used in the present invention is electric wire and ultraviolet rays. When using ultraviolet A: 1, it is preferable to add a sensitizer to the compound of Isu.

Sensitized j1i is not particularly limited, but ultraviolet #1L
It is preferable to have a relatively large extinction coefficient at a wavelength of 254.313.365 nm, which produces the bright line spectrum of a mercury lamp commonly used as a JI (i) radiation source. Typical examples include acetophenone, benzophenone, benzoin ethyl ether, Benzyl methyl ketal, benzyl ethyl ketal, benzoin isobutyl ketone,
Aromatic ketones such as hydroxydimethyl phenyl ketone, 1-hydroxycyclohexylphenyl ketone, 2-2 diethoxy 7tophenone, and Mitchell+s ketone can be used.

The mixing ratio of the sensitizer is 0.5 to 20 parts by weight, preferably 2 to 15 parts by weight, per 100 i = ai of the compound.
>1X, more preferably 3 to 10 parts by weight.

When coating the intermediate layer on the support, various organic solvents can be used as necessary. When the intermediate layer coating liquid is a liquid, it may be solvent-free. Organic solvents that can be used include ketones such as acetone, methyl ethyl ketone, methyl imbutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, propatool, and butanol; tp
Ethyl acetate, butyl acetate, ethyl lactate, glycol monoethyl ether-based esters: ether, glycol dimethyl ether, glycol monoethyl ether, glycol ether based on dioxanation; benzene, Cool types such as toluene and xylene (172% water purple); methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, dichlorobenzene and the like.

+: The thickness of the intermediate layer described above is preferably 0.1 to 2 μm in terms of the di'i constant after Shigetani conversion by radiation 1 ((Toki 4), and the surface glitter of the layer is 0.1 to 2 μm. It is preferable that the viscosity is 0.01 μm or less.For this purpose, the viscosity can be reduced by using a relatively low-strength compound or organic solvent additive 11.
One of the ways to achieve this effect is to eliminate the so-called leveling effect that goes up to the leveling system. The polyether acrylate in the present invention has a low viscosity and has a thin J
'L'i coating is possible, and smoothness by leveling is easily achieved.

Electron layer (scanning method, double scanning method, or curtain beam method can be adopted as an accelerator, but the curtain beam method is preferable because it is relatively inexpensive and can obtain a large output.As for the electron beam characteristics, the accelerating voltage is 10~ The acceleration voltage is 1000 kV, preferably 50 to 300 kV, and the absorption voltage is 0.5 to 20 megarads, preferably 1 to 10 megarads.The acceleration voltage is 10 kV.
In the following cases, the amount of energy transmitted is insufficient and 1oook
If it exceeds v, the efficiency of energy used for polymerization decreases and is not economical.

If the absorbed dose is less than 0.5 megarads, the curing reaction will be insufficient; if it exceeds 20 megarads, the energy efficiency used for curing will decrease, the irradiated object will generate heat, and especially the plastic support will deform, which is undesirable. .

The magnetic layer provided on the polymerized hardened layer of the present invention may be mainly composed of ferromagnetic powder and a binder, or may be made of a thin magnetic metal.

The method for forming the thin magnetic metal blade applied to the present invention may be a method of forming an annular shape in a vacuum chamber or a plating method, and the forming speed of the gold R thin blade is fast, the manufacturing process is simple, Alternatively, a method of forming a film in a vacuum chamber is preferable, which has advantages such as not requiring wastewater treatment. A method of forming a film in a vacuum chamber is a method in which the substance or its compound to be deposited is deposited as vapor or ionized vapor on a substrate in a dilute gas or vacuum space, such as vacuum evaporation method or sputtering. This corresponds to the method, ion blating method, chemical vapor phase plating method, etc.

Furthermore, in the present invention, ferromagnetic gold I to be the magnetic recording layer
IjN includes iron, cobalt, nickel and other ferromagnetic metals, or Fe-Co, Fe-Ni, Co-Ni
.

Fe-3i1Fe-Rh, Co-P, Co-
B, Co-5i, Co-V.

Co-Y, Co-La, Co-Ce, Co-P
r, Co-5m, Co-Pt.

Co-Mn1Fe-Co-Ni, Co-N1-PlC
o-Ni -B1Co -N i-Ag%Co -N
i −Na, Co −N i −Ce, Co −N
i-Zn1Co-Ni-Cu1Co-Ni-W,
A ferromagnetic alloy such as Co-Ni-Re%Co-Sm-Cu is formed into a thin film by a method of forming a film in a vacuum chamber or a plating method, and the film thickness is determined when used as a magnetic recording medium. 0.05fim ~2tsmf
) Range Te: F) Special K 0.14m to 0.44m is preferable.

Ferromagnetic powder and various additives used in the magnetic layer of the present invention,
For details on organic solvents, dispersion/coating methods, etc., see JP-A-52-108,804 and JP-A-54-21.804.
No. 54-46,011 can be applied to the present invention as required.

〔Example〕

The present invention will be explained in more detail below using Examples.

In the examples, "parts" indicate parts by weight.

Example 1 Polyethylene glycol #600 diacrylate (manufactured by Kyoeisha Yushi, 14EGA) was deposited on a polyethylene terephthalate support with a surface roughness of 0.01 μm and a thickness of 14.5 μm.
was applied, and electron beam irradiation was performed at an acceleration voltage of 165 kV and a beam current of 5 mA, with an absorbed dose of 2 Mrad.

The coating layer thickness after curing is 0.5 μm.

After dispersing the magnetic coating liquid with the following composition in a ball mill for 10 hours,
Trimethylolpropane adduct of triincyanate compound (approximately 760 molecules, NGO content 13.3 wt%,
Product name: Bayer A, G, manufactured by Desmoju/L/L
-75J)(') 75vtt961i:e:22 parts of LfrrMWl was added and dispersed with high speed shearing for 1 hour, and the magnetic coating solution was poured. The obtained coating liquid was applied on the upper side of the layer so that the thickness after drying was 4 μm. Then, it was oriented in a DC magnetic field and dried by blowing hot air at 100°.

After drying, it was calendered and slit into 1/2 inch width to obtain video magnetic tape sample No. 1.

Comparative Example 1 Magnetic tape sample 2 was obtained in the same manner as in Example 1 except that the intermediate layer was not applied.

Example 2 Based on Example 1, a coating liquid having the following composition was prepared in place of 14EGA, and after coating, it was irradiated with ultraviolet rays for 1 second using a gQW/cm mercury lamp.

The thickness after differential hardening was 0.5 μm.

The magnetic tape sample r! was otherwise processed in the same manner as in Example 1. 13
I got it.

Example 3 Magnetic tape sample 4 was obtained in the same manner as in Example 1 except that a polyethylene terephthalate support having a surface roughness of 0.015 μm was used.

Comparative Example 2 A magnetic tape sample No. 5 was obtained in the same manner as in Comparative Example 1 except that a polyethylene terephthalate support having a surface roughness of 0.015 μnt was used.

Example 4 A magnetic tape sample No. 6 was obtained in the same manner as in Example 1 except that a polyethylene terephthalate support having a surface roughness of 0.020 μm was used.

Example 5 An intermediate layer was provided in the same manner as in Example 1. A Co--Ni (Ni; 20 wt%) magnetic film was provided on the layer by oblique vapor deposition to a thickness of 100 oX to obtain magnetic tape sample salt 7.

Comparative Example 3 Magnetic tape sample salt 8 was obtained in the same manner as in Example 5 except that the intermediate layer was not applied.

Comparative Example 4 Magnetic tape sample No. 9 was obtained in the same manner as in Example 1 except that ethylene glycol diacrylate was used instead of urethane acrylate A.

Video sensitivity and Cc were measured for the above samples. Outline of measurement method! Shown below.

Video sensitivity: The reproduction output at 4 MHz was measured using a VH3 type VTR (manufactured by Matsushita Electric Corporation, trade name: rNV-8800J).

C/N: 3 MHz and 3,5 MI (z (7
)' lj transmitted wave (carrier) was recorded and the ratio of carrier to noise (corresponding to S/N) when reproduced was measured using Comparative Example 1 as a reference (±0 dB).

The results are shown in the table.

〔Effect of the invention〕

As is clear from the table, the surface roughness of the support is 0.01
μm or more, and an intermediate layer containing polyether acrylate is provided between the support and the magnetic tti, and by controlling the surface roughness of the intermediate layer to 0.01 pm or less under radiographic radiation, video sensitivity and C/ It can be seen that a magnetic recording medium with significantly improved N content can be obtained.

Agent Buri (8107) (left non-tree) Blue 1st (and 3 others) Procedural amendment February 1-9, 1939 Patent application No. 241050 February 2, 1982, Title of invention: Magnetic recording Media 3, Person making the amendment Relationship to the case: Patent applicant name (52θ) Fuji Photo Film Co., Ltd. Kasumigaseki Building Post Office P.O. Box 49 Eikou Patent Office Telephone (581)-9601 (Representative) 7
, 414 of the subject of the amendment "Detailed explanation of the invention ψJ" 8. Translation of the content of the amendment "Detailed explanation of the invention" as follows: Second, correct "give" to "give" 2) Same page 4, line 11, "Attata."
and correct it.

6) On page 10, line 6 from the bottom, "slipness" is amended to "sliding".

4) On page 13, line 11, change "ro, 01μm" to "0.
010 μm,” he corrected.

5) On page 13, line 13, "Kyoei Yushisha" is amended to "manufactured by Kyoei Yushisha." .

6) On page 17, line 8, insert “Comparative example 1 (sample A2) as standard (±odB)” after “reproduction output” 1.

Claims (2)

[Claims] (1) An intermediate layer containing a polyether having two or more acryloyl groups or methacryloyl groups in the molecule is provided between the nonmagnetic support having a surface roughness of 0.01 μm or more and the magnetic layer, and the layer is exposed to radiation. A magnetic recording medium characterized by being irradiated. (2) The magnetic recording medium according to claim (1), wherein the intermediate layer has a surface roughness of 0.01 μtn or less.