JPS60205827A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having good lubricity particularly at low to high temp. and having excellent runnability and durability by incorporating specific aliphat. ester as a lubricating agent in a magnetic layer. CONSTITUTION:A magnetic layer is formed on a substrate by using a magnetic paint contg. necessary carbon black and dispersant, etc. in the magnetic powder incorporated therein with the ester (A) of alcohol expressed by the formula I (R1 is an aliphat. group of 5-10C, R2 is an aliphat. group of 1-7C) and carboxylic acid of 2-16C and a binder. The ester A incorporated alone as the lubricating agent in the magnetic paint has good compatibility with the magnetic layer and contributes to an improvement in slipperiness and durability at a low temp. but the slipperiness and durability at a high temp. can be further improved by making combination use of the ester B expressed by the formula II (R3 is an aliphat. group of 8-22C, R4 is an aliphat. group of 1-12C, R5, R6 are H or CH3, n is >=1). The slipperiness and durability particularly at a low temp. are further improved by incorporating an ester C obtd. by reaction of >=2 kinds of aliphat. carboxylic acids of 8-18C and an alcohol having 3 or 4 OH in the molecule together with the esters A, B into the above-mentioned paint.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic recording medium in which a magnetic layer is formed on a base material, and in particular has improved durability over a wide temperature range from low to high temperatures. Related to magnetic recording media.

[Prior art]

It is known that a lubricant is contained in a magnetic layer for the purpose of increasing the durability of magnetic recording media such as video tapes and floppy disks. Conventionally, such lubricants include silicone oil, fluorine oil, long chain fatty acid ester, hydrocarbon compound, and long chain fatty acid.

Long chain fatty acid amides etc. are used.

By the way, in recent years, it has become important to improve the reliability of magnetic recording media, and especially in digital recording such as 7Q discs, the reliability of each bit is important, and even after long-term use, even one bit is important. Severe durability is required so that dropout does not occur.

As floppy disks became more common, devices with temperatures of 10°C
It may be used at low temperatures below (for example, 0°C atmosphere) or at high temperatures of 40'C or higher (for example, 50°C atmosphere).

Against this background, the level of durability required of floppy disks has become increasingly strict, and there is a desire for improved durability from low to high temperatures. In the prior art, long-fatty acid esters, particularly monofunctional long-chain fatty acid esters, are often used as lubricants for the purpose of increasing durability. For example, 7-tyl stearate, 7-butoxyethyl stearate, etc. have been used, but although floppy disks using such long-chain fatty acid esters generally show good durability when used at room temperature, their durability in ambient air is poor. There is a problem. Also, 2-hexyltecylbeto, 4-to, 2-heyacylbidecyl stearate. Esters such as 2-octyldodecyl stearate and 2-hequinlutecyl stearate have relatively good durability under high-temperature atmospheres, but magnetic powders containing urethane binders, carphone black, lecithin, and α-Fe , O, etc., there is a problem in compatibility with magnetic paints.

[Purpose of the invention]

The inventor proceeded with the development of a lubricant with excellent lubricity, a wide applicable temperature range, good durability, and good inheritability with magnetic paint, and discovered completely new knowledge regarding slipperiness at low temperatures. This is what led to the present invention.

Therefore, an object of the present invention is to provide a magnetic recording medium with improved durability over a wide temperature range from low to high temperatures.

[Structure of the invention]

The object of the present invention is basically to provide a magnetic recording medium in which a magnetic layer containing magnetic powder, a binder, and a lubricant is formed on a base material, in which the lubricant is a carbonic acid 5 having 12 to 16 carbon atoms. ~1O aliphatic group, R2 has 1 to 1 carbon atoms
7 aliphatic group. This is achieved by a magnetic recording medium characterized by containing a small amount of esters with alcohol represented by ().

The lubricant used in the present invention is an ester (N is at least Preferable examples of the carbonic acid having 12 to 16 carbon atoms include lauric acid, myristic acid, and palmitic acid. Examples of the alcohol include 2-ethylhexyl alcohol and 2-pentylnonyl alcohol.

2-hexyl tecyl alcohol, 2-hentyl nonyl alcohol, 2-butyl undecyl 7 alcohol', 2-
Preferable examples include hebutyldodecyl alcohol and 2-hexyldodecyl alcohol. The above esters (preferred specific examples of N include 2-xyl tesyl palmitate, 2-hexyl nonyl palmitate, 2-
Examples include hexyldotesyl myristate.

Such ester (Al) can be used alone, but it can also be used in combination with other lubricating esters.

This lubricating ester is an aliphatic group represented by the general formula 8 to 22, R4 is an aliphatic group having 1 to 12 carbon atoms,
R3, bird is l-1f: or CHs-, respectively. Also n
is an integer of 1 or more, and is an ester f8+. By using this ester (Bl) in combination, the slipperiness and durability at high temperatures are further improved.
Compatibility with magnetic paint also improves.

Such an ester (B1 specifically includes, for example, ethylene glycol mobutyl ether stearate, etc.)
ethylene glycol monobutyl ether oleate 9 J-J-Lencri: l-lumo/butyl ether stearate, noethylene glycol heptobutyl ether oleate, ethylene glycol heptanophthyl ether palmicate, diethylene glycol monozotyl ether urarate, (Diethylene glycol monoethyl ether stearate, diethylene glycol monophenyl ether stearate, triethylene glycol methyl ether palmitate, dibrohylene glycol 7-ethyl ether oleate) Q9. These include, for example, 2-handed gelicol methyl ester, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monoalkyl ethers: diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethin. polyethylene glycol monoalkyl ether, represented by glycol monobutyl ether; polyethylene glycol monoalkyl ether, represented by dipropylene glycol monomethyl ether, and alcohols such as lauric acid, Milisken, and palmyl ether.

It can be synthesized by the reaction of long-chain carbonic acids such as stearic acid, instearin-oleic acid, and linoleic acid. Among these esters, those in which n is 2 or more are preferred.

Furthermore, the above-mentioned ester and ester (a lubricating ester preferably used in combination with Bl) contain at least two or more aliphatic carbon components having 8 to 18 carbon atoms and 3 or more carbon atoms in the molecule.
Esters obtained by reaction with a polyhydric alcohol component having 1 or 4 hydroxyl groups (including 0). , stearic acid, isostearic acid, onic acid, linoleic acid, etc. Among these groups, 21 or more fat ti'? You can add a small amount of 1boku. Also trivalent or 41
Most songs: 1 song Alcohol includes trimethylolpropane and trimethyloleethane.

Examples include pesotaerythritol and glycerin. Such esters (C) include, for example, trimethylolpropane (1 mol) and tocabric acid (3 mol).
ester of trimethylolpropane (1 mol) and caprylic I'Il (3 mol), diester of trimethylolpropane (1 mol) and lauric acid (3 mol),
Ester of glycerin (1 mol) and caprylic acid (3 mol), trimethylolethane (1 mol), tocabric acid (3 mol)
mol) esters, etc.

Such an ester (C1 is the ester and the ester f
When used in combination with Bl, it is extremely effective in improving the durability of the magnetic layer of a magnetic recording medium over a wide temperature range, particularly in improving the durability and slipperiness under a low-temperature atmosphere, and also has good compatibility with magnetic paints. The reason for this is not clear, but it can be assumed that the lubricant exhibits properties that allow it to maintain its fluidity even at low temperatures, and that the balance between aliphatic groups and polar groups is suitable for magnetic coatings.

The amount of the above-mentioned lubricant is preferably 0.3 to 12% by weight based on the total weight of the magnetic layer. If the amount is less than 0.3% by weight, the lubricant will have poor durability, and if it exceeds 12% by weight, there will be too much lubricant, which may cause problems such as softening of the coating film. , durability will decrease.

As mentioned above, the basic feature of the present invention is to use ester (5) as a lubricant. If an ester of a carboxylic acid having 11 or less carbon atoms is used instead of the ester, the evaporation loss in a high temperature atmosphere will be large and the durability of the magnetic recording medium will be reduced. Furthermore, if a calphone ester having carbon number of X7 or more is used instead of the ester, the compatibility with the magnetic paint will be poor (the magnetic paint will easily cause layer separation, and the stability will be significantly impaired.Similarly) If the number of carbon atoms in R, in the ester is 4 or less, the evaporation loss in a farm-temperature atmosphere becomes large, and if it is 11 or more, it causes problems in compatibility with magnetic paints.Similarly, when the number of carbon atoms in R2 is is 8
In the latter case, compatibility with magnetic paint becomes a problem.

Furthermore, as the magnetic powder and binder in the present invention, conventionally known magnetic powder and binder can be used, respectively. As the magnetic powder, for example, 1
- Fe, O,.

Co-containing r Fe, O,, Fe, O,, Co-containing F
e, O,.

Examples include barium ferrite. Examples of binders include binders of urethane resins, vinyl chloride resins, and epoxy resins.

Furthermore, dispersion agents (eg lecithin, etc.).

Antistatic agents (e.g. carbon black, etc.).

Conventionally known additives such as reinforcing agents (eg α-Fe, O, l alumina) may also be added.

In the present invention, the magnetic j- is formed on the substrate.

As this base material, a plastic film, particularly a polyethylene terephthalate polymer film, can be used.

The magnetic layer provided on the surface (one side or both sides) of the base material is formed by coating a magnetic paulownia material represented by, for example, 1-Fe or O8, dispersed in a resin binder. Coating can be done using a conventionally known coating method. For example, air doctor coat, blade coat, air knife coat, squeeze coat, impregnation coat, lino (-slow/shi:ff-
h,) Lance Far Roll Coat), f5 Beer Coat, Kiss Coat, Cast Coat.

Spray coat etc. can be used for 11j. The thickness of the magnetic layer is 0
．． 1 to 20μ is preferable.

In the present invention, the lubricant can be contained by dispersing the magnetic material in the resin binder and adding and dispersing it during interpolation, or by overcoating the surface of the magnetic layer with PC.

The magnetic recording medium in the present invention refers to magnetic tape floppy disks and V&K tapes, but is not limited to these examples.

〔Example〕

Next, examples of the present invention will be described. In the Examples and Comparative Examples of Nagoro (1) below, IMa (all J indicates "weight".

Example 1 1- Fe, 0, 70 parts Magnetic recording binder made of polyurethane elastomer, salt-vinyl acetate co-electrolyte having hydroxyl group, and epoxy resin 17//Carbon black 5 tt Dispersant 2'' Crosslinking agent made of polyincyanate 2 tt Tetrahydrofuran/cyclohexanone mixed solvent 180 parts 11'lt agent: 2-hexyldecyl palmitate 4,
077 The above composition is mixed and dispersed to prepare a magnetic paint.

It was placed in a partially sealed bone container and allowed to stand at 25°C for 24 hours. Dry the remaining magnetic paint on a 75 μm polyethylene terephthalate film to a thickness of approximately 3 μm.
After drying, the mixture was coated on both sides so as to have the following properties, and after drying, the surface was subjected to a calender treatment and then punched out into a disk shape to obtain a floppy disk.

Example 2 A magnetic paint was prepared in the same manner as in Example 1 except that 4.0 parts of 2-hexyldecyl dodecyl myristate was used instead of 2-hexyldecyl palmitate as the lubricant in Example 1. A floppy disk was obtained in the same manner as in Example 1 using the paint.

Example 3 2-hexyldecyl palmitate 2 was used instead of 2-hexyldecyl palmitate as the lubricant in Example 1.
．． A floppy disk was obtained in the same manner as in Example 1, except that 5 parts and 1.59 parts of diethylene glycol monobutyl ether stearate were used.

Example 4 In Example 1, 2-hexyl decyl palmitate was replaced with 2-hexyl decyl palmitate as a lubricant.
A 7a tube disc was obtained in the same manner as in Example 1, except that 1.1 part of diethylene glycol mononisthyl ether stearate and 1 part of ester were used.

Here, the ester is a polyfunctional ester obtained by reacting a mixed acid consisting of 1 mole each of caprylic acid, capric acid, and lauric acid with 1 mole of trimethylolpropane.

Example 5 2-hexyl/nyl palmitate 2 was used instead of 2-hexyldecyl palmitate as the lubricant in Example 1.
．． A floppy disk was obtained in the same manner as in Example 1 except that 5 parts of diethylene glycol monobutyl ether stearate were used.

Example 6 Example 1 except that the amount of 2-hexyldecyl palmitate added as a lubricant was changed by 1.0 parts.
I obtained a floppy disk in the same way.

Comparative Examples 1 to 7 Floppy disks were obtained in the same manner as in Example 1, except that the lubricant having the composition shown in Table 1 was used instead of 2-hexyldecyl palmitate.

Table 1 Composition of Comparative Examples The magnetic paints of the Examples and Comparative Examples prepared in this manner were placed in a tightly closed glass container for 24 hours and allowed to stand at 25°C for 24 hours. Evaluation was made from three points of view: (1) Is there any layer separation of the paint? (2) Is the carbon separated and does not stand out on the surface? (3) Is the lubricant separated and does it stand out as shown in Table-1?

The evaluation was divided into the following three ranks.

+11 No change from immediately after preparation -〇(2) A black striped pattern of carbon is slightly observed on the surface. -△ (3) Separated liquid layers are observed on the surface. Also, the entire surface is covered with separated carbon. → × The results are shown in Table 2.

Furthermore, the durability of the floppy discs of the Examples and Comparative Examples manufactured in this way was evaluated as described below using an 8-inch commercially available floppy disk device.

Load the head with a head tension of 30I, rotate it continuously on the same track, and set the output level to the initial value of 8.
The time it took to reach 0% or less was defined as the durability time of the medium. It should be noted that the held tension of a normal floppy disk device is 10 to 20.9, and the held tension of 30.9 used illegally can be said to be quite severe. Also, the temperature of the funeral environment is 0°C (low temperature) and 50°C (^warm). Durability was indicated by the durability time in the above test.

Table 3.4 shows the durability evaluation results obtained in the above Examples and Comparative Examples.

Table 2 Evaluation table of magnetic paint 3 Durability at 0°C (unit: 2 hours) Table 4 Durability at 50°C (unit: 2 hours) [Effects of the invention] The magnetic recording medium of the present invention has a wide range of durability from low to high temperatures. It has improved durability, especially at low temperatures.

The reason for this is that the lubricant used in the present invention has a moderate affinity with the polymer binder and has the ability to maintain its fluidity even at low temperatures, so it provides good lubrication at the interface between the head and the magnetic layer. By adding Stell, monofunctional fatty acid ester, and mixed acid polyfunctional ester, the lubricity of the interface between the head and the magnetic layer at high temperatures is also improved for the same reason, and it can be used over a wide range of temperatures. It has good durability and slipperiness.

Claims (1)

[Scope of Claims] l A magnetic recording medium in which a magnetic layer containing magnetic powder, a binder, and a lubricant is formed on a base material, wherein the lubricant is an aliphatic material having a carbon number of 12 to 16 and a carbon prime number of 5 to 10. group, and R2 is an aliphatic group having 1 to 7 carbon atoms. ) A magnetic recording medium comprising at least an ester (5) with an alcohol represented by: 2. The magnetic recording medium according to claim 1, wherein the content of the ester (4) is in the range of 0.3 to 12 times the amount of the lubricant in the magnetic layer. 3 Magnetism, 1 contains the ester (AIR) as a lubricant.
, R6 R5 is an aliphatic group having 8 to 22 carbon atoms, l(4 is an aliphatic group having 1 to 12 carbon atoms, R,, R, are each H or CH, -, or n is The magnetic recording medium according to claim 1, characterized in that it contains a small amount of an ester (Bl) represented by an integer of 1 or more. ) and esters (
The content of Bj is 0.3 to 12% by weight of magnetic j-.
4. The magnetic recording medium according to claim 3, wherein the magnetic recording medium is within the range of . 5. In the magnetic layer, as a lubricant, the above-mentioned ester and ester (B) and a mixed fatty acid component of two or three or more types of fatty acids having 8 to 18 carbon atoms, and a polyhydric compound having 3 or 4 Vr hydroxyl groups in the molecule. The magnetic recording medium according to claim 1 or 3, characterized in that it contains at least ester (C) obtained by reaction with an alcohol component. 6 @The above ester as a lubricant (mm, ester (81
and ester (the content of 0 is 0.3 to 0 in the magnetic layer)
6. The magnetic recording medium according to claim 5, wherein the magnetic recording medium is in a solid form with a weight of 12%.