JP3353505B2 - Cleaning solution for magnetic head and magnetic head using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head cleaning liquid containing a compound soluble in a general-purpose solvent as a main component, and a magnetic head coated with the magnetic head cleaning liquid.

[0002]

2. Description of the Related Art In general, a magnetic recording medium, particularly a magnetic tape, is slid with a magnetic head at a high speed in the process of recording / reproducing a magnetic signal. In this case, the running must be performed smoothly and stably. . However, in the above magnetic recording medium, the surface of the magnetic layer is smoothed for high-density recording, so that a substantial contact area with the magnetic head increases, An image sticking phenomenon called brown stain is likely to occur.

When such a phenomenon occurs, the output level is reduced and the durability of both the magnetic recording medium and the magnetic head is deteriorated. Is being held. For example, in a so-called coating type magnetic recording medium having a magnetic layer mainly composed of a magnetic powder and a binder, it is possible to internally add a lubricant to the magnetic layer or to apply a lubricant on the magnetic layer. Attempted. Also, in a magnetic recording medium of a so-called metal magnetic thin film, a lubricant is applied on a magnetic layer together with a rust preventive or the like.

However, when a lubricant widely used in the past is applied to the surface of the magnetic layer, the coefficient of friction is reduced at first and the running property is improved. However, there is a problem that the effect is reduced due to being scraped off by the sliding member. Further, in a coating type magnetic recording medium, even if a lubricant is applied to the surface of the magnetic layer, the lubricant diffuses into the magnetic layer, and thus is depleted particularly after aging. When the lubricant on the surface of the magnetic layer is depleted in this way, the organic substance in the lubricant or, in the case of a coating type magnetic recording medium, the organic substance in the binder easily adheres to the magnetic head again. . further,
When the organic substance attached to the magnetic head is oxidized, the organic substance is changed to a substance insoluble in a general-purpose solvent, resulting in brown stain.

In order to solve this problem, the magnetic head is periodically cleaned before brown stain is generated on the magnetic head, or the above-described contamination of the magnetic head is prevented. A cleaning solution for this purpose has been commercially available, such as Deck Solvent (trade name, manufactured by ING Corporation).

The cleaning liquid is mainly composed of a perfluoropolyether having a polar group. If the cleaning liquid is used to clean the sliding surface of the magnetic head with the magnetic recording medium, it is possible to remove the adhered organic substances and magnetic powder. Etc. can be removed. In addition, the presence of the polar group makes it possible to adsorb to the metal and make it difficult for dirt to adhere to the magnetic head. By applying this cleaning liquid to the sliding surface of the magnetic head in advance, the generation of brown stain is prevented. can do.

[0007]

However, in the above-mentioned cleaning liquid, a perfluorocarbon (C _n F _{2n + 2} ) solvent is used as a solvent because perfluoropolyether as a main component does not dissolve in a general-purpose solvent. This has to be done, which makes the price of this cleaning liquid very high. Other than perfluorocarbon solvents, chlorofluorocarbons (so-called CF)
Although it can be dissolved in a (C-fluorocarbon) -based solvent, many of the chlorofluorocarbon-based solvents are said to have a bad effect on the global environment.

Accordingly, the present invention has been proposed in view of the above circumstances, and has as its object to provide a magnetic head cleaning liquid which has an excellent magnetic head cleaning effect and can be dissolved in a general-purpose solvent. It is another object of the present invention to provide a magnetic head in which the cleaning liquid for a magnetic head is applied so that no dirt is attached to a sliding surface with a magnetic recording medium and no brown stain is generated.

[0009]

The cleaning solution for a magnetic head according to the present invention has been proposed to achieve the above-mentioned object, and comprises a perfluoropolyether having a hydroxyl group at a terminal and a long-chain carboxylic acid. Is dissolved in a solvent. Here, the ester compound of a perfluoropolyether having a hydroxyl group at a terminal and a long-chain carboxylic acid is represented by the following general formulas (1) and (2).

R ^f1 —CH ₂ OCOR ¹ (1) R ² COOCH ₂ —R ^f2 —CH ₂ OCOR ³ (2) where R ^f1 and R ^f2 represent a perfluoropolyether group, R ¹ , R ² and R ³ each represent a hydrocarbon group derived from a long-chain carboxylic acid. As a method for synthesizing such an ester compound, for example, a long-chain carboxylic acid chloride is gradually added to a mixture of a perfluoropolyether having a hydroxyl group at a terminal and a tertiary amine used as a catalyst. At 60 ° C. for 2 hours. After completion of the reaction, the resultant is washed with water and purified by silica gel chromatography using hexane as a mobile phase, whereby an ester compound of a perfluoropolyether having a hydroxyl group and a long-chain carboxylic acid can be separated.

In the above general formulas (1) and (2),
The hydrocarbon groups represented by R ¹ , R ² and R ³ have 1 carbon atom.
It is preferably 0 or more, a double bond, a branch, a ring,
It does not matter whether or not aromatic is present. In addition, N,
Complex elements such as O, P, and S may be contained. R ¹ , R
^{If the} number of carbon atoms in the hydrocarbon group ² or R ³ is less than 10, there is a possibility that the effect as a cleaning liquid or the solubility in a solvent may be impaired. However, in the general formula (2) of the ester compound of the polyfunctional perfluoropolyether, R ² and R ³ do not necessarily have to be hydrocarbon groups having the same structure, and one of them is a hydrocarbon group having 10 or more carbon atoms. If so, the other may be H.

On the other hand, the monofunctional perfluoropolyether group represented by R ^f1 includes the following structural formula (3):
^{Examples of the} polyfunctional perfluoropolyether group represented by R ^f2 include those represented by (4) and (5).
Examples include, but are not limited to, those represented by the following structural formula (6). _{F (CF 2 CF 2 CF 2} O) k ··· (3) CF 3 [OCF (CF 3) CF 2] l (OCF 2) m ··· (4) F [CF (CF 3) CF 2 O ] _N (5) (OCF ₂ CF ₂ ) _p (OCF ₂ ) _q (6) where k, l, m, n, p, and q are all integers of 1 or more, and Molecular weight of 6 as fluoropolyether
What is necessary is just to make it into the range of 00-5000. If the molecular weight is too small, the cleaning effect is deteriorated, while if it is too large, the effect of the terminal group bonded thereto is relatively deteriorated.

The above-mentioned ester compound of a perfluoropolyether having a hydroxyl group at a terminal and a long-chain carboxylic acid is dissolved in various general-purpose solvents without using a fluorocarbon or chlorofluorocarbon solvent.
Specifically, hydrocarbon solvents such as toluene and hexane, ketone solvents such as acetone and methyl ethyl ketone, and alcohol solvents such as ethanol and isopropanol are preferably used. of course,
These may be appropriately mixed and used. However, it is desirable to select a solvent having a boiling point of 50 ° C. or higher so as to withstand friction when sliding with the magnetic recording medium.

The cleaning liquid for a magnetic head as described above exerts a cleaning effect by being held on the sliding surface of the magnetic head with the magnetic recording medium, but causes the cleaning liquid for the magnetic head to be held on the magnetic head. The method is not particularly limited. For example, the magnetic head may be manufactured as usual and then applied by dipping. Further, when the user cleans the magnetic head, the magnetic head may be applied again with a cotton swab or the like.

The thickness of the magnetic head cleaning liquid applied to the magnetic head is preferably from 0.3 nm to 10 nm, more preferably from 0.5 nm to 5 nm. If the coating thickness is too thin, the magnetic head cannot be held for a long time. On the other hand, if the coating thickness is too thick, the spacing increases and sticking to the magnetic recording medium occurs. Problems arise.

As a magnetic head to which the present invention is applied,
It may have any configuration, particularly when recording / reproducing or when starting / stopping a recording / reproducing operation.
A magnetic head that slides on a magnetic recording medium is suitable. Specifically, general ferrite heads, metal
Examples include an in-gap (MIG) type head, a laminated type head, an inductive head, a magnetoresistive (MR) type head, and the like. In addition, as the material of these magnetic heads, any conventionally known materials can be used.

In addition, writing / writing is performed by this magnetic head.
As the magnetic recording medium from which reading is performed, any of those conventionally applied to each magnetic head can be used, and there is no limitation. Therefore, the configuration of the magnetic layer may be a coating type mainly composed of a magnetic powder and a binder, or a metal magnetic thin film type. The shape is not limited at all, and may be any of conventionally known shapes such as a tape shape, a disk shape, and a drum shape.

The magnetic layer of such a magnetic recording medium also retains the magnetic head cleaning liquid held by the magnetic head, exerts a lubricating effect, and constantly applies the magnetic head cleaning liquid to the magnetic head. You may make it possible to supply.

[0019]

The ester compound of a perfluoropolyether having a hydroxyl group at the terminal and a long-chain carboxylic acid has a large water repellency and has an excellent action of lowering the surface energy. For this reason, when applied to the sliding surface of the magnetic head with the magnetic recording medium, the adhesion of dirt to the sliding surface is suppressed.
Therefore, it is possible to prevent the stain from being oxidized to brown stain. As a result, the durability of the magnetic head and the magnetic recording medium can be improved, and a reduction in output level can be prevented.

The ester compound of perfluoropolyether is more soluble than perfluoropolyether alone, and is soluble in various general-purpose solvents, and uses a fluorocarbon or chlorofluorocarbon solvent. No need. Further, since it has a polar group, it is strongly fixed to a magnetic head. This cleaning effect is not impaired even under severe conditions such as low temperature.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described, but it goes without saying that the present invention is not limited to these embodiments. Example 1 In the present example, a cleaning liquid obtained by dissolving an ester compound of a compound having hydroxyl groups at both ends of a polyfunctional perfluoropolyether and a long-chain carboxylic acid in ethanol was used.

Specifically, as the ester compound,
The structure and molecular weight of the perfluoropolyether group represented by R ^f2 in the aforementioned general formula (2), R ² , R ³
The structure of the hydrocarbon group resulting from the long-chain carboxylic acid shown in Table 1 was prepared as shown in Table 1, and this was dissolved in ethanol to obtain a cleaning liquid of Example 1.

[0023]

[Table 1]

Then, the cleaning liquid was held on a magnetic head. In the magnetic head used here, a pair of magnetic core halves 1 and 2 are formed of a ferromagnetic oxide, for example, single crystal ferrite, as shown in FIG. A ferromagnetic metal thin film having a high saturation magnetic flux density Bs, such as an FeAlSi alloy (Sendust), is continuously formed from the front gap formation surface to the back gap formation surface on the ferromagnetic metal thin film formation surface which is notched obliquely. Numeral 3 is the one formed by adhesion. The pair of magnetic core halves 1 and ₂ abut each other via a gap material such as SiO ₂ , and the contact surface of the ferromagnetic metal thin film 3 forms a magnetic gap. The groove in which the ferromagnetic metal thin film 3 is formed is filled with a non-magnetic material 4, and the groove for regulating the track width is filled with a non-magnetic material 5, respectively. Are formed with winding grooves 6 and 7 for restricting the depth of the magnetic gap g and winding the coil 8.

The above-described cleaning liquid is applied to the sliding surface 9 of the magnetic head having the above-mentioned structure with the magnetic recording medium at a coating thickness of 0.5 to 5 nm, whereby the magnetic head of the first embodiment is formed. Obtained. Examples 2 to 4 In this example, an ester compound having a structure of a hydrocarbon group derived from a long-chain carboxylic acid and a molecular weight of a perfluoropolyether group different from that of Example 1 was used as a cleaning liquid.

Specifically, Table 1 shows the structure of the hydrocarbon group derived from the long-chain carboxylic acid represented by R ² and R ³ and the molecular weight of the perfluoropolyether group represented by R ^f2 . Except for preparing such an ester compound, cleaning liquids of Examples 2 to 4 were obtained in the same manner as in Example 1.
Then, the cleaning liquid as described above was applied to the magnetic head in the same manner as in Example 1 to obtain the magnetic heads of Examples 2 to 4. Examples 5 to 7 In this example, an ester compound of a compound having a hydroxyl group at a terminal of a monofunctional perfluoropolyether and a long-chain carboxylic acid was used as a cleaning liquid.

Specifically, as the ester compound,
The structure and molecular weight of the perfluoropolyether group represented by R ^f1 in the general formula (1) and the structure of the hydrocarbon group derived from the long-chain carboxylic acid represented by R ¹ shown in Table 1 are as shown in Table 1. Except for the preparation, cleaning liquids of Examples 5 to 7 were obtained in the same manner as in Example 1. Then, the cleaning liquid as described above was applied to the magnetic head in the same manner as in Example 1 to obtain the magnetic heads of Examples 5 to 7. Examples 8 to 13 In this example, a cleaning solution having a different solvent for dissolving the ester compound as described above was used.

Specifically, the ester compound prepared in Example 1 was replaced with isopropanol instead of ethanol,
By dissolving in methyl ethyl ketone, the cleaning liquids of Examples 8 and 9 were obtained, respectively.
By dissolving the ester compound prepared in the above in isopropanol, methyl ethyl ketone, toluene and hexane instead of ethanol, Example 1 was conducted in this order.
0, Example 11, Example 12, and Example 13 were obtained.

Then, the cleaning liquid as described above was applied to a magnetic head in the same manner as in Example 1, and
No. 3 magnetic heads were obtained. Comparative Examples 1 to 3 In this comparative example, a perfluoropolyether compound having a hydroxyl group at a terminal, a perfluoropolyether compound having a carboxyl group at a terminal, a perfluoropolyether compound having a carboxyl group at a terminal and a carbon number 1
Was used as a cleaning liquid.

Specifically, using the perfluoropolyether compounds shown in Table 2, the lubricants of Comparative Examples 1 to 3 were obtained. Note that perfluorohexane was used as a solvent for the lubricants of Comparative Examples 1 and 2, and perfluorooctane was used for the lubricant of Comparative Example 3.

[0031]

[Table 2]

Then, the above-described cleaning liquid was applied to a magnetic head in the same manner as in Example 1, and Comparative Examples 1 to 3 were applied.
Magnetic head was obtained. Comparative Example 4 In this comparative example, none of the cleaning liquids described above was used. That is, a magnetic head having the same configuration as in Example 1 except that the cleaning liquid was not applied was prepared, and this was used as the magnetic head of Comparative Example 4. Evaluation of characteristics here, Examples 1 to 13, actually performs the regenerating operation of the magnetic tape with a magnetic head shown in Comparative Examples 1 to 4,
The contamination of each magnetic head and the error rate accompanying the level reduction were examined.

To produce a magnetic tape for measurement,
First, the following materials were prepared. Ferromagnetic metal powder 100 parts by weight Vinyl chloride-vinyl acetate copolymer 10.5 parts by weight Polyurethane resin 10.5 parts by weight Carbon (antistatic agent) 5 parts by weight Methyl ethyl ketone 150 parts by weight Toluene 150 parts by weight Cyclohexanone 100 parts by weight Stearic acid 2 parts by weight of butyl ester These materials were mixed in a ball mill for 24 hours and taken out through a filter.
By stirring for 0 minutes, a magnetic paint was obtained.

Next, the magnetic paint was dried on a polyethylene terephthalate film having a thickness of 8 μm to a thickness of 3 μm after drying.
m, and then oriented in a magnetic field, dried, wound up, calendered, and cut into 1/2 inch width to complete a magnetic tape. Then, in an atmosphere of 25 ° C. and 60% RH or an atmosphere of 40 ° C. and 80% RH, the above-described configuration is achieved by the drives mounted with the magnetic heads shown in Examples 1 to 13 and Comparative Examples 1 to 4. After data writing / reading was repeatedly performed for 32000 blocks of the magnetic tape having the above for 4 hours, contamination of each magnetic head and an error rate accompanying a level reduction were examined.

The magnetic head is stained as follows: if the surface of the ferromagnetic metal thin film 3 in the vicinity of the front gap is not stained, Δ if it is slightly stained, and x if more than half is oxidized and brown stain is generated. evaluated. In addition, as an error rate, a ratio of blocks where normal writing / reading could not be performed was measured. Hereinafter, Examples 1 to 7
Table 3 shows the measurement results of the magnetic heads of Examples 8 to 13.
Table 4 shows the measurement results of the magnetic head of Example 1, and Table 5 shows the measurement results of Comparative Examples 1 to 4.

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Table 5]

From the above results, in the magnetic heads of Examples 1 to 13 shown in Tables 3 and 4, the brown stain did not occur and the error rate could be reduced. It can be seen that in the magnetic heads of Comparative Examples 1 to 4 shown, dirt adheres and the error rate increases. From this, it can be seen that the application of the cleaning liquid makes it difficult for dirt to adhere to the sliding surface of the magnetic head with the magnetic recording medium. Also,
As the cleaning liquid, it is better to use an ester compound of a perfluoropolyether compound having a hydroxyl group at a terminal and a long-chain carboxylic acid shown in Examples 1 to 13 than those shown in Comparative Examples 1 to 3. It can be seen that an excellent cleaning effect is exhibited.

[0040]

As is clear from the above description, the cleaning liquid for a magnetic head according to the present invention exhibits an excellent cleaning effect for a long time even under severe use conditions. Moreover, various hydrocarbon solvents can be used as the solvent, and no fluorocarbon or chlorofluorocarbon solvents are required.

Therefore, when this is applied to the sliding surface of the magnetic head with the magnetic recording medium, it is possible to prevent dirt from adhering to the sliding surface and to prevent the occurrence of brown stain. As a result, the durability of the magnetic head and the magnetic recording medium can be improved, and a reduction in output level can be prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration example of a magnetic head to which the present invention is applied.

[Explanation of symbols]

 1, 2 magnetic core half 3 ferromagnetic metal thin film 4, 5 non-magnetic material 6, 7 winding groove 8 coil 9 sliding surface

Claims (4)

(57) [Claims] 1. A cleaning solution for a magnetic head, wherein an ester compound of a perfluoropolyether having a hydroxyl group at a terminal and a long-chain carboxylic acid is dissolved in a solvent. 2. The cleaning liquid for a magnetic head according to claim 1, wherein the long-chain carboxylic acid has a hydrocarbon group having 10 or more carbon atoms. 3. The cleaning liquid for a magnetic head according to claim 1, wherein the solvent comprises one of a hydrocarbon solvent, a ketone solvent, and an alcohol solvent. 4. A magnetic head, wherein the cleaning liquid for a magnetic head according to claim 1 is held on a sliding surface with a magnetic recording medium.