JPS6045935A - Medium for magnetic recording - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent durability from low to high temp., more particularly in low temp. environment by incorporating a lubricating agent compounded with a specific polyfunctional fatty acid ester mixture and monofunctional fatty acid ester in a magnetic layer. CONSTITUTION:A magnetic layer in which a lubricating agent compd. contg. the polyfunctional fatty acid ester mixture obtd. by reaction of >=2 kinds of C8-18 fatty acids and polyhydric alcohol having 3 or 4 OH groups in one molecule and monofunctional fatty acid ester, i.e., the resulted product or reaction of C8-18 fatty acid and C1-18 aliphat. alcohol is incorporated together with magnetic powder in a binder is formed. The ester with the alcohol having ether bond such as glycol monoether or the like is preferably used fully or partly as the monofunctional fatty acid ester. The recording medium which has good lubricity and excellent durability in 0-50 deg.C temp. environment, more particularly in low-temp. environment is thus obtd.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a magnetic recording medium in which a magnetic layer is formed on a base material. Related to magnetic recording media.

(Prior Art) It is known to include a lubricant in a magnetic layer for the purpose of increasing the durability of magnetic recording media such as video tapes and floppy disks. Such a lubricant is silicone mail.

Fluorine oils, long chain fatty acid esters, hydrocarbon compounds, long chain fatty acids, long chain fatty acid amides, etc. are known.

By the way, the reliability of magnetic recording media -1- has become important in recent years, and especially in digital recording such as FloraPie disks, the reliability of each bit 1-1o is important, and even for long-term use, 1 bit A high degree of durability is required to prevent dropouts.

As floppy disks become more common (as floppy disks become more common),
It may be used under conditions such as a low temperature below (eg, 0° C. atmosphere) or a high temperature of 40° C. or higher (eg, 50° C. atmosphere).

Against this background, the level of durability required of floppy disks has become even more severe, and there is a desire for improved durability from low to high temperatures. In the conventional technology, I! is used for the purpose of increasing durability. Long-chain fatty acid esters, especially monofunctional long-chain fatty acid esters, are often used as Im agents, such as butyl stearate, butoxyethyl stearate, and the like. Although they generally have good durability when used at room temperature, there are problems with their durability when used in high-temperature or low-temperature environments.

Therefore, the present inventor proceeded with the development of a lubricant with excellent lubricity, a wide applicable temperature range, and good durability. As a result, the present inventor obtained completely new knowledge regarding slipperiness at low temperatures19 and arrived at the present invention. be.

A lubricant made of a combination of a -C monofunctional fatty acid ester and a polyfunctional fatty acid ester has been attempted, but no improvement in durability has been observed.

However, a lubricant containing a monofunctional aliphatic Nisdel and a polyfunctional fatty acid ester mixture made by mixing a specific fatty acid and reacting the mixture with a trivalent or tetravalent polyhydric alcohol has surprisingly poor durability. A significant improvement was found. In particular, we have found that the effect of improving durability in low-temperature atmospheres is outstanding, and have completed the present invention (C1).

(Structure of the Invention) The present invention provides a magnetic recording material in which a magnetic layer is formed on a base material, comprising a monofunctional fatty acid ester and a polyfunctional fat 11.
/i, an acid ester in the magnetic layer, in particular, the polyfunctional fatty acid ester contains a mixed fatty acid consisting of two or more fatty acids having 8 to 18 carbon atoms and 3 in one molecule.
A magnetic recording medium characterized in that C is obtained by reaction with a polyhydric alcohol having 1 or 4 water fill groups.

The present invention will be explained.

In the present invention, the monofunctional fatty acid Wa] nystyl refers to one containing one sprue bond, and the polyfunctional fatty acid one sprue refers to one containing two or more ester bonds.

The magnetic recording medium of the present invention includes magnetic sheets, floppy disks, and! ! This is not limited to this example.

In the present invention, when a magnetic layer is formed on a base material, a monofunctional fatty acid ester and one sprue of a polyfunctional fatty acid are contained in the magnetic layer together with a magnetic material, thereby producing a magnetic recording medium. Improved slipperiness and durability.

In the present invention, a plastic sheet typified by a poly(1-ethylene terephthalate) polymer can be used as the base material. The magnetic layer provided on the surface (single side or surface) of the base material is one in which a magnetic material represented by γ-Fe 10 g is dispersed in a resin binder and coated. In the present invention, when dispersing the magnetic material in the resin binder,
A mixture of a monofunctional fatty acid ester and a polyfunctional fatty acid ester having a specific composition is added and dispersed. Of course, the mixture of monofunctional fatty acid ester and polyfunctional fatty acid ester of the present invention can also be impregnated onto the surface of the magnetic layer by overcoating.

The monofunctional fatty acid ester used in the present invention is one obtained from a fatty acid having 8 to 18 carbon atoms and an aliphatic alcohol having 1 to 18 carbon atoms.

Here, as a fatty acid with carbon number 8 to 18, linear 1
Examples of fatty acids containing branched or unsaturated fatty acids include lauric acid, myridic acid, valmidic acid, stearic acid, isostearin, MLJ leic acid, and linoleic acid.

The aliphatic alcohol is an aliphatic alcohol having 1 to 18 carbon atoms, including linear, monobranched, and unsaturated alcohols, and may contain atoms other than carbon such as ether bonds. For example, ``, All Nord. Butanol, hexanol. Examples include 2-ethylhexyl alcohol, isostearyl alcohol, stearyl alcohol, and oleyl alcohol.

The above-mentioned aliphatic alcohols for obtaining monofunctional fatty acids include those containing an ether bond in the molecule, such as methoxyethyl alcohol, 1-xyethyl alcohol, butoxyethyl alcohol, di]-brene glycol-monoethyl ether, diethylene glycol- Monobutyl ether and the like can be suitably used as a component of the lubricant of the present invention. When using a fatty acid ester containing an ether bond in the molecule,
It has the effect of improving lubricity in low temperature regions.

Next, a polyfunctional fatty acid ester using a mixed acid is obtained by mixing at least two types of acids having 8 to 18 carbon atoms and reacting these with 311i or a tetrahydric polyhydric alcohol. It is something. Here, as fatty acids,
caprylic acid, capric acid, lauric acid, myristic acid,
Examples include valmitic acid, stearic acid, isostearic acid, oleic acid, and linoleic acid. Two or more fatty acids are selected from these groups, but a small amount of carboxylic acid may be added to this group.

Moreover, as trihydric or tetrahydric polyhydric alcohol, 1 to rimedylol propane, trimethylol ethane.

Examples include pentaerythritol.

It is presumed that in the present invention C, by reacting a mixed fatty acid with a polyhydric alcohol, the proportion of the acid component C1 bonded to the polyhydric alcohol becomes a different type of carboxylic acid.

The addition of lubricants made of these monofunctional fatty acid Nisdel and mixed acid polyfunctional esters is Iit! The range is preferably from 0.1% to 15% based on the total weight of 1.1iJj.

Various types of lubricants can be added in small amounts, but if the total weight of these exceeds 15% by weight, the adhesive strength and abrasion resistance of the coating film will decrease, which is not preferred.

In addition, in the magnetic layer of the present invention, the known Ill&1g
Contains powder, binder, and dispersant (lecithin, etc.).

C may also be used by appropriately adding known additives such as antistatic agents (carbon, etc.), reinforcing agents (γ-Fe2O3° alumina, etc.).

The lubricant containing the monofunctional fatty acid Nisdel of the present invention and a specific mixed polyfunctional fatty acid ester has a durability of t! l, especially (It) is extremely effective in improving durability in a humid temperature atmosphere, but its true nature is not clear.Probably, the lubricant has the property of maintaining its fluidity even at low temperatures. It can be assumed that.

The present invention is effective in a magnetic recording medium in which a magnetic layer is formed using at least one binder selected from urethane, vinyl chloride, and epoxy binders.

(Example) Examples of the present invention will be described below with a focus on floppy disks, but it goes without saying that the magnetic recording medium of the present invention is not limited to floppy disks. Note that all "parts" described in Examples are "parts by weight."

Example 1 γ-Fe 103 70 parts Magnetic recording binder consisting of polyurethane elastomer, salt-vinyl acetate copolymer containing hydroxyl groups, and epoxy resin 17n carbon 1
Easy 5-part dispersant 2. Crosslinking agent consisting of polyisocyanate 1.2! ! Tel-Rahydrofuran/Cyclohexanone mixed solvent 180# Lubricant Butoxyethyl stearate 1 1.5 n Ester A1
．． 5II Note that ester A is a polyfunctional ester obtained by reacting a mixed fatty acid consisting of 81 moles of caprylic acid, nopuric acid, and lauric acid with 1 mole of trimethylolpropane.

After mixing and dispersing the above composition, it was coated on both sides of a 75 μm polyester stell film substrate to a dry thickness of about 3 μTn, and after drying, the surface was calendered, cross-linked by heating, and punched into a disk shape. I got a floppy disk.

Example 2 As the lubricant in Example 1, 1 to 2 parts of di]-brene glycol monobutylene I and Nisdel 81 were substituted for the lubricant and ester in Example 1. Using .5 parts, prepare a floppy disk of 1!1k in the same manner as in Example 1'.

Here, ester B is a polyfunctional clay ester obtained by reacting a mixed fatty acid consisting of 81 moles of caprylic acid, capric acid, and oleic acid with 1 mole of trimethylicolpropane.

Example 3 In Example 1, 1.5 parts of butoxydiylstearate and 1.5 parts of ester C were used instead of butoxyethyl sulfate and ester A as the C lubricant,
A floppy disk was obtained in the same manner as in Example 1.

Here, C Nisdel C is a polyfunctional ester obtained by reacting a mixed fatty acid consisting of 81 moles of jJ prylic acid, capric acid, and lauric acid with 1 mole of glycerin.

Example 4 A floppy disk was prepared in the same manner as in Example 1 except that 1 to 2 parts of diethylene glycol monoethyl 1-dervalmite and 1 part of ester D were used instead of butoxyethyl sulphate and ester Δ as lubricants. Got the disc.

Here, ester D is 1.5 moles of A-rein III.

It is a polyfunctional ester obtained by reacting a mixed fatty acid consisting of 0.5 mol of stearic acid and 1 mol of caprylic acid with 1-glycerin.

Example 5 A floppy disk was obtained in the same manner as in Example 1 except that the amounts added to butoxyethyl spherule 1 and ester were changed to 0.4 part and 0.4 part, respectively.

Comparative Example In Example 1, a lubricant having the composition shown in Table 1 was used in place of the lubricant 1 to 1 and the ester to obtain a FjI disc in Example 1. .

Table 1 Composition of Comparative Example The durability of the floppy disks of the Examples and Comparative Examples thus manufactured was evaluated as follows using an 8-inch commercially available floppy disk device. The head was loaded with a head density of 30 g, and the medium was rotated continuously on the same track, and the durability time of the medium was determined at the time when the output j level became 80% or less of the initial value. Note that the helad tension of a normal floppy disk device is 10 to 20.
The 30g helad tension used in the anzu method is
It can be said that the durability t'l evaluation criterion f1 for floppy disks is quite severe. 〔Atmosphere ff1U is 0℃
It is.

Classified into three ranks based on durability: C1.

Durability rank Δ: Durability time 250 hours or more B: 15
0 to 250 hours n c: IT 150 hours or less According to the above Examples and Comparative Examples, the durability of 7Pl
illi results are not shown in Table 2.

Example 6 A floppy disk was obtained in the same manner as in Example 1 except that 1.5 parts of 2-ethylhexyl stearate was used instead of butoxyethyl stearate.

Table 2 Durability Rank (Effects of the Invention) As described in 1 above, the present invention has achieved a high degree of low-temperature durability that could not be achieved with conventional single or mixed fatty acid ester lubricants. By blending with a polyfunctional ester, specific improvement could be achieved.

The reason for this is not clear, but by using a mixed acid in a polyfunctional ester, the acid component that binds to the polyol becomes a different type of carboxylic acid, lowering the freezing point and making it easier to maintain the liquid state. This is thought to be due to the synergistic effect and interaction between C and monofunctional ester, which increases the lubrication drop at low temperatures.

Procedure nertx JE Book September ψ, 1980 To the Commissioner of the Patent Office, Patent Application 2 filed on August 24, 1988, Name of invention Representative discussion of magnetic recording medium Hiroshi Iino [1] Specification page 12 Line 10 [Obtained Bee disk. Example 6 A floppy disk was obtained in the same manner as in Example 1 except that 11.5 times 2-ethylhexyl stearate was used instead of butoxyethyl stearate. Ta. Correct with J.

(2) Bright [l@Page 14 bottom line to page 15 pH/I
The line ``Example 6 In Example 1... a disk was obtained.

” will be deleted.

(3) On page 16, line 6 of the specification, "lubricating drop, 1" has been corrected to "lubricating effect J."

that's all

Claims (1)

[Scope of Claims] 1) A magnetic recording medium in which a magnetic layer containing a monofunctional fatty acid ester and a polyfunctional fatty acid ester is provided on a base material, wherein the polyfunctional fatty acid Nisdel has a carbon number A magnetic recording medium obtained by reacting two or more mixed fatty acids of 8 to 18 fatty acids with a polyhydric alcohol having 3 or 4 hydroxyl groups in the molecule. . 2) The magnetic recording medium according to claim 1, wherein all or part of the monofunctional fatty acid ester has a -full bond.