JPS6057528A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve lubricity and wear resistance of a magnetic layer by using hydroxyalkyl ester of a specific fatty acid as a lubricating agent. CONSTITUTION:A magnetic recording medium holds the hydroxyalkyl ester of the fatty acid expressed by the formula I . The sum of the number of carbon atoms of R and the number of carbon atoms of the hydroxylalkyl group in the formula I is more particularly preferably >=10. If <10, the lubricating effect is poor. The amt. of the hydroxylalkyl ester of the fatty acid to be added is made 0.2-4wt% by the weight of magnetic powder in the case of incorporating the same into a magnetic layer and 0.2-20wt% by the weight of a binder in the case of incorporating the same into a back coating layer. The top coating layer consisting of the above-mentioned lubricating agent is made 1-1,000mg/m<2> at the amt. of coating in the case of forming the top coating layer or coating layer consisting of said lubricating agent by coating. The hydroxyalkyl ester of the fatty acid is obtd. by the esterification reaction of the fatty acid and alkylene glycol as shown by the formula II.

Description

Detailed Description of the Invention This invention relates to magnetic recording media such as magnetic tapes and magnetic disks, and its purpose is to improve the lubricity and abrasion resistance of the magnetic layer, thereby improving running stability and durability. Our objective is to provide an excellent magnetic recording medium.

Magnetic recording media such as magnetic tapes run while coming into contact with magnetic materials, so the magnetic layer is required to have a small coefficient of friction and excellent running stability. Because it comes into intense sliding contact with a magnetic head, etc., it is required that the magnetic layer has minimal wear and excellent durability.

For this reason, in order to improve the β′1 lubricity and wear resistance of the magnetic layer, the internal addition method, in which a lubricant is mixed in advance into the magnetic layer, or the Totsubukou method, in which a lubricant layer is formed on the surface of the magnetic layer, is used. ~
Laws are being enforced. In the above method, higher fatty acids and their esters, silicone oil, etc. are generally used as lubricants.

Generally, by using fatty acids such as those mentioned above as a lubricant for the magnetic layer, it is possible to impart good running properties to the magnetic recording medium, but on the other hand, it has the disadvantage that it tends to impair durability.

With the aim of imparting good runnability to magnetic recording media without deteriorating their durability, the inventors of the present invention conducted extensive studies on various lubricants, and found that hydroxyalkyl fatty acids were found as a lubricant that met the above objective. The present invention was completed by discovering that Nisdel is suitable.

That is, the present invention provides a magnetic recording medium having a magnetic layer on a non-magnetic support, wherein the magnetic recording medium has the formula % (where 1t represents a hydrocarbon group having 1 to 29 carbon atoms). , n represents an integer of 3 to 12).

This fatty acid hydroxyalkylnisdel ζ is
The sum of the carbon numbers of the hydroxyalkyl groups of R1 is particularly important in the present invention, and it is particularly preferable that the sum is 10 or more. If the sum of the number of carbon atoms in R and the number of carbon atoms in the hydroxyalkyl group is less than 10, the lubricating effect of the present invention will be poor.

When included in the magnetic layer, the amount of the hydroxyl()-olester of fatty acid used in the present invention is preferably 02 to 4 parts by weight based on 100 parts by weight of the magnetic powder in the magnetic layer. Further, when it is included in the Barafco-1 layer on the back side of the base as described later, it is preferably 02 to 20 parts by weight based on 100 parts by weight of the binder in the Barafco-1 layer. Furthermore, when forming a Tosobuco-1 layer or a coating layer made of the above lubricant as described later,
Depending on the amount of lubricant applied, it is 1 to 1000 m! 7/rr
Desired to be l, it is obtained by the esterification reaction of a fatty acid and an alkylene glycol as shown in the following formula.

(Ch-COOI-1 [+ l-lo-CnTI2n 0
1-1- R-C-0-CnHznOI-T+l-I2
0 (tadashi 1 (1 represents a hydrocarbon group of] ~ 29,
n represents an integer from 3 to 12. ) The above-mentioned fatty acids include saturated fatty acids such as caproic acid, caprylic acid, notupric acid, lauric acid, myristic acid, palmitic acid, and stearic acid, and unsaturated fatty acids such as oleic acid, elaidic acid, linoleic acid, and latelunic acid. Can be mentioned.

Further, examples of the alkylene glycol include propylene glycol, 1,3-butylene gellicol, and 1,4-funashi-fuglycol. 2.3-butylene glycol, 1,
Examples include 5-bentanediol, 2,4-bentanediol, neopentyl glycol, 1,6-hexanediol, and the like.

Next, the structure of a magnetic recording medium, such as a magnetic tape, according to the present invention is illustrated in FIGS. 1 to 5.

Q茗ν FIG. 2 shows a state in which a layer 3 made of a six-layer lubricant is formed on the surface of the magnetic layer 2. Third
The figure shows a state in which a coating layer 4 made of a lubricant is formed on the back surface of a non-magnetic support 1 by one stroke M. FIG. 4 shows a state in which a coating layer 6 manufactured by Honjo Kiri Co., Ltd. is formed in the hard coat layer 5 formed on the back side 1'-) of the non-magnetic support 1.

Note that Barafco-1 and layer 5 are provided for various purposes, but
The purpose of this is to appropriately control the surface roughness of the back surface, thereby stabilizing running performance and preventing static electricity. For this reason, the Barafco-1 layer is coated with a mixture of carbon and fluff in the binder.
Furthermore, non-magnetic pigments such as α-Fe203, alumina, Kuruk, etc. may be mixed.

In the magnetic recording medium of the present invention, the lubricant of the magnetic tape can be held at various positions within the magnetic layer 2 or on the front and/or back surfaces of the magnetic layer 2.

As the magnetic powder that can be used in the magnetic layer of the present invention, γ-Fe
2O3, Fe: +O<, r-Mixed crystal of Pe203 and Fe3O4, γ-F with 1- or coated cohar 1-
ezO (or Fc304, Cr0z, barium ferrite, various alloy powder magnetic materials (e.g. Fe-Co, Co
-Ni, Fe-Co -Ni, Fe-Co
-B, Pe -Cn -Cr -B, Mn -Bi
, Mn-AI, Fe-Co-V, etc.), iron nitride, etc., and two or more of these may be used in combination. Binders that can be used in the magnetic layer include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-hinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, and vinyl chloride-vinylidene chloride copolymer. copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinyritine chloride copolymer, meccrylic ester-vinyritine chloride) ten copolymer, meccrylic ester-styrene copolymer Coalescence, thermoplastic polyurethane resin, phenoxy resin, polyvinyl fluoride, vinylidene chloride-acryloni-1-lyl copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-meccrylic acid copolymer, acrylonitrile-cyclodiene −
Acrylic acid copolymer, polyhinyl phthyral, polyvinyl acecool, cellulose derivative, styrene-bucdiene copolymer, polyester resin, phenol resin, epoxy resin, thermosetting polyurethane resin, urea resin, melamine resin, Alkyra 1 -゛resin, urea formaldehyde resin, etc.

In preparing the magnetic paint, organic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone,
Ketones such as cyclohexanone, esters such as methanol, efnol, propatool, and buknol, glycol ethers such as ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, and dioxane, and aromatic hydrocarbons such as benzene, toluene, and xylene. , aliphatic hydrocarbons such as hexane and heptano, nitropropane, etc. can be used alone or as a mixture. Non-magnetic supports to which the magnetic paint prepared with this organic solvent is applied include polyesters such as polyethylene terebrate, polyolefins such as polypropylene,
Examples include cellulose derivatives such as cellulose triacef-1 and cellulose diacetate, polycarbonate, polyvinyl chloride, polyamide, polyimide, metal materials such as aluminum and copper, and paper. Further, as a solvent for applying the top coat layer and coating layer comprising the lubricant according to the present invention, a weakly polar, low boiling point solvent such as Freon, hexane, and Ehnol can be used.

Further, as a magnetic recording medium to which the hydroxyalkyl ester of fatty acid of the present invention can be applied as a lubricant, magnetic recording media using a magnetic layer formed by coating magnetic powder together with a binder as described above are suitable. The present invention is not limited to media, but is also applicable to metal thin film magnetic recording media. This metal thin film type magnetic recording medium has a magnetic metal such as cobal-1 (Co), iron (Fe), nickel (NI) on a non-magnetic support.
) or its alloy by plating, vapor deposition, ion blating, spackling, etc. This metal thin film type magnetic recording medium has a high magnetic flux density because it does not require the use of a binder, and is useful for short wavelength, high density recording because it is formed into a very thin layer.

The present invention will be explained below with reference to Examples. It goes without saying that the present invention is not limited to these Examples.

[Example 1] Co adhering r -Fe2O3' 100 parts by weight Vinyl chloride-vinyl acetate copolymer 18 (V-C, manufactured by Company C)
VAGH) Polyurethane resin 12 〃 (N-5033 manufactured by Nippon Polyurethane Co., Ltd.) Carbon (antistatic agent) 5 〃 Lecithin (dispersing agent) ■ ... Stearic acid hydroxypropyl ester 1 〃Hexyl laurate 1 ・Notyl ethyl chloride 150 weight The composition was mixed in a ball mill for 24 hours, filtered through a filter, and immediately before coating, 1 part by weight of a curing agent was added and stirred for 30 minutes. . This magnetic paint is applied to a 2μ thick polyethylene terephragm coated with a thickness of 5μ after drying.
It was coated so that

After subjecting this to J-Renter treatment, it was cut into % inch pieces to prepare sample tapes.

[Example 2] Hydroxypropyl myristate was used instead of hydroxypropyl stearate in Example 1, and a magnetic paint having the same composition as in Example 1 was used in the same manner as in Example 1. A sample tape was created.

[Comparative Example 1] Co-adhered r-Fe203 100 parts by weight Vinyl chloride-vinyl acetate copolymer 18 (manufactured by V, C, C, Inc.)
VAGH) Polyurekne resin 12 parts by weight (manufactured by Nippon Polyurethane Co., Ltd. N-5033) Carbon 5
, 7 Lecithin I 〃 Hexyllaure 1- 1. ,.

Methyl ethyl ketone 150. .

Methyl isophthyl ketone 150 A sample tape was prepared using the above composition in the same manner as in Example 1.

[Example 3] → The magnetic layer of the nopple tape prepared in Comparative Example 1 was prepared using a n-hexane solution containing stearic acid and hydroxypropyl ester with a weight ratio of 05 to 80 mj; l/m. Apply it so that (
+-Tub coat) to obtain a sample tape.

[Example 4] A 5% by weight n-hexane solution of hydroxypropyl laurate was added to the magnetic layer of the sample tape prepared in Comparative Example 1.
A sample tape was obtained by applying (top coat) a 5% n-hexane solution to a coating amount of 80 mg/m of hydroxypropyl lauric acid.

[Ratio Example 2] A sample tape was prepared in the same manner as in Example 1, using stearic acid instead of stearic acid hydroxypropyl ester in Example 1, and using a magnetic paint having the same composition as in Example Ⅰ. did.

[Comparative Example 3] A 05% by weight solution of myristic acid in n-hexane was applied to the magnetic layer of the sample tape prepared in Comparative Example 1 so that the coating amount of myristic acid was 80 mjj/m (top coat [comparison)]. Example 4 100% of cobalt (co) was deposited on a base made of polyethylene terephthalate with a thickness of 12μ by an oblique vapor deposition method.
A magnetic layer was formed by vacuum evaporation to a thickness of 0 A, and then cut into pieces of 1.5 inch to prepare sample tapes.

[Example 5] In the magnetic layer of the sample tape prepared in Comparative Example 4, 01% by weight of stearic acid hydroxypropyl ester1]-
Apply a hexane solution so that the coating amount of hydoxyprobyl stearate is 20"97m (to obtain a top coat).

The running properties and durability of the above sample tapes were measured. The results are shown in the table below.

In the table () is f! 3 under the conditions of Wl, degree 45℃, humidity 80%
Shows the take after ace for days.

In addition, in the table 1-1, scratches are on the aluminum drum.
After running the shuttle for a minute, visually observe the scratches on the magnetic layer. If there are no scratches, mark it as ◎, then in descending order of scratches as ○, △,
It was evaluated as ×.

From the above, the magnetic recording medium using the lubricant according to the present invention is
Both running stability and surface durability were insufficient.

In particular, according to the present invention, the running deterioration after oral change, which has been a conventional problem with magnetic recording media produced by the Totubuko i method, can be solved.

[Brief explanation of drawings]

1 to 5 are cross-sectional views showing examples of the structure of a magnetic recording medium according to the present invention. 1...Nonmagnetic support 2... 1.2 Three-layer patent applicant
1 Patent attorney Koike Mimi 1) Sakae Mura ---

Claims (1)

[Claims] A magnetic recording medium having a magnetic layer on a non-magnetic support, the magnetic recording medium having the formula % (where R represents a hydrocarbon group having 1 to 29 carbon atoms, and n is A magnetic recording medium comprising a hydroxyalkyl ester of a fatty acid represented by the formula (representing an integer from 3 to 12).