JPH05307743A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having satisfactory running property and durability by forming a magnetic layer with the ester of carboxylic acid having an ether bond in the molecular chain with partially fluorinated alcohol on the surface or in the interior. CONSTITUTION:When a magnetic layer contg. a ferromagnetic metal as a magnetic material is formed on a nonmagnetic substrate to obtain a magnetic recording medium such as a magnetic tape or disk, a magnetic layer with the ester of carboxylic acid having at least one ether bond in the molecular chain with partially fluorinated alcohol on surface or in the interior is formed as the magnetic layer. The objective magnetic recording medium having satisfactory durability and running property is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic tape or a magnetic disk, and more particularly to the above medium having improved running property and durability.

[0002]

2. Description of the Related Art Generally, a magnetic powder is coated on a non-magnetic substrate together with a binder, or a ferromagnetic metal or an alloy thereof is deposited on the non-magnetic substrate by vacuum deposition or the like. In the magnetic recording medium, the magnetic layer is in strong contact with the magnetic head or the like during recording and reproduction, and thus the magnetic layer is easily worn.

In particular, a ferromagnetic metal thin film type magnetic recording medium formed by vacuum evaporation or the like, and a magnetic recording medium prepared by coating a metal magnetic powder with a binder have extremely good surface smoothness. Therefore, although it has excellent high recording density characteristics, it has some drawbacks such as insufficient durability, a large friction coefficient, and poor running due to sticking.

Therefore, as disclosed in JP-B-56-30609, JP-A-60-109028, JP-B-60-10368, etc., aliphatic compounds such as fatty acids and fatty acid esters are formed on the magnetic layer. It is often practiced to provide a protective layer made of a compound or a fluorine-based compound such as perfluoropolyether to reduce the friction coefficient and improve the running property and durability.

[0005]

However, when the relative speed between the magnetic recording medium and the magnetic head becomes high and the frequency of use in the still state of the video tape increases,
With the above-mentioned conventionally used aliphatic compounds, a sufficient lubricating effect cannot be obtained, and the magnetic layer using a ferromagnetic metal as a magnetic material cannot be sufficiently protected.

Fluorine-based compounds such as perfluoropolyether lack homophilicity with organic solvents and binders used in the production of magnetic recording media, so that they can be uniformly dispersed in the magnetic layer. Insufficient uniform retention on the surface of the magnetic layer makes it impossible to exert a lubricating effect for a long period of time, and sufficient running property and durability cannot be obtained.

In view of the above-mentioned conventional circumstances, the present invention seeks a lubricant which is particularly effective for a magnetic layer using a ferromagnetic metal as a magnetic material, thereby improving the running property and durability of the magnetic recording medium. The purpose is to get.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, as a lubricant of this kind, a specific aliphatic carboxylic acid and a partially fluorinated alcohol were used. Knowing that by using the ester of, it is possible to exert a good lubrication effect over a long period of time, and it is possible to greatly improve the repeatability and still durability.
This invention has been completed.

That is, according to the present invention, in a magnetic recording medium such as a magnetic tape or a magnetic disk in which a magnetic layer made of a ferromagnetic metal as a magnetic material is provided on a non-magnetic substrate, the surface or the inside of the magnetic layer. Relates to a magnetic recording medium characterized by having an ester of a carboxylic acid having an ether bond in its molecular chain and a partially fluorinated alcohol (hereinafter referred to as a polyether fluorinated ester) It is a thing.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The structure and function of the invention The polyether fluorinated ester used in the present invention has at least one ether in its molecular chain.
Carboxylic acid and partial Hutu fluorinated alcohol having ether bond - shall apply in esters of Le, for example, the following _{expression; C x H 2x + 1 O} (C y H 2y O) a (CH 2) b COO (CH ₂ ) _m (CF ₂ ) _n CF ₃ (where x ≧ 1, y ≧ 1, a ≧ 0, b ≧ 1, m ≧ 0,
n ≧ 1). Further, the structure is not limited to this, and may have an unsaturated bond or a branch in the molecule.

Such a polyether fluorinated ester may be used alone as a lubricant, or may be used in combination with other conventionally known lubricants. Lubricants that can be used in combination include, for example, fatty acids or metal salts thereof, aliphatic esters, aliphatic amides, aliphatic alcohols, monosulfides, paraffins, silicone compounds, perfluoropolyethers and the like. Can be mentioned.

In the present invention, in order to allow the above-mentioned polyester type fluorinated ester to be present on the surface or inside of the magnetic layer, the magnetic layer containing the ester is used to form the magnetic layer, or A solution of the ester dissolved in a suitable solvent such as methyl ethyl ketone is prepared, and the magnetic layer is immersed in this solution, or the above solution is applied or sprayed on the surface of the magnetic layer to make it uniform on the surface of the magnetic layer. It can be applied.

In the former method using a magnetic paint, the amount of the polyester type fluorine-containing ester used is 100% of the magnetic powder.
The amount added is usually 0.5 to 10 parts by weight per part by weight, and in the latter surface deposition method, it is usually in the range of 0.1 to 100 mg / m ² , particularly 0. 5-20mg
It is recommended that the amount of deposition be in the range of / m ² . If it is too small, the desired effect will not be obtained, and if it is too large, it will cause a drop in output and dropout.

In the present invention, the magnetic layer on the non-magnetic substrate is formed by coating a magnetic coating material containing a ferromagnetic metal powder and a binder on the substrate, or a magnetic material made of a ferromagnetic metal on the substrate. It is formed by depositing it on the substrate by a known thin film forming means such as vacuum deposition, ion plating, spattering, and plating.

Ferromagnetic metal powders for magnetic paints include F
Magnetic metal or alloy powder such as e powder, Co powder, Fe-Ni powder is used, and the binder is polyurethane resin, polyester resin, vinyl chloride resin, fibrin resin, butyral resin, etc. In addition to the various known resins mentioned above, a crosslinking agent such as a polyisocyanate compound is used. Further, as a magnetic material for forming a thin film, Fe, Co,
Ni, Co-Ni alloy, Co-Cr alloy, Co-P, C
o-Ni-P or the like is used.

In the magnetic recording medium of the present invention, a binder resin such as a vinyl chloride resin, a polyurethane resin or a fibrin resin and a powder such as carbon black are provided on the surface of the non-magnetic substrate opposite to the magnetic layer. A back coat layer as a main component may be provided.

The magnetic recording medium of the present invention is in sliding contact with a magnetic head such as a magnetic tape having a synthetic resin film such as a polyester film as a non-magnetic substrate and a magnetic disk or magnetic drum having a disk or a drum as a non-magnetic substrate. Includes various forms of construction.

[0018]

As described above, according to the present invention, the running property of a magnetic recording medium having a magnetic layer containing a ferromagnetic metal as a magnetic material is improved by using a polyether fluorinated ester as a lubricant component. And durability can be improved significantly.

[0019]

EXAMPLES Next, examples of the present invention will be described, but the present invention is not limited to these examples. Hereinafter, "parts" means "parts by weight".

Example 1 In a three-necked flask equipped with a water content measuring tube, CH ₃ OCH _{2 was} added.
30 parts of CH ₂ OCH ₂ CH ₂ COOH, CF ₃ (CF ₂ ) ₅
80 parts of (CH ₂ ) ₂ OH and a small amount of SnO as a catalyst were taken, and heated to 120 to 150 ° C. in a nitrogen gas atmosphere for dehydration esterification. After the completion of dehydration, SnO was removed by filtration and the product was purified by distillation with a molecular distillation apparatus. A magnetic coating material was prepared as follows using the thus obtained polyether type fluorinated ester A as a lubricant component.

Α-Fe magnetic powder 100 parts Vinyl chloride resin (MR-110 manufactured by Zeon Corporation) 15 parts Polyurethane resin (N-2309 manufactured by Nippon Polyurethane Industry Co., Ltd.) 10 parts Carbon black 1 part α-Al ₂ O ₃ powder 0.5 parts Polyether-based fluorinated ester A 3 parts Trifunctional low molecular weight isocyanate compound (Cornerate L manufactured by Nippon Polyurethane Industry Co., Ltd.) 6 parts Cyclohexanone 150 parts Toluene 150 parts

A magnetic paint was prepared by mixing and dispersing the above composition in a ball mill for 100 hours. Apply this paint on a polyethylene terephthalate film with a thickness of 11 μm,
A magnetic tape was formed by coating, drying and mirror-finishing so that the thickness after drying was 3 μm, and then slitting to a width of 8 mm to prepare a video tape.

Example 2 A polyethylene terephthalate film having a thickness of 10 μm was filled in a vacuum vapor deposition apparatus, and the oxygen gas pressure was 5 × 10 ⁻⁵ torr.
Co-Ni alloy is heated and vaporized under the residual gas pressure of the film and continuously obliquely incident on the polyethylene terephthalate film to form Co-Ni-O [Co: Ni = 8].
0:20 (weight ratio)] and a ferromagnetic metal thin film having a thickness of 0.2 μm was formed.

Then, this ferromagnetic metal thin film was prepared as in Example 1.
After immersing in a 0.2 wt% isopropyl alcohol solution of the polyether fluorinated ester A obtained in step 1 and drying to form a protective layer, a slit is made to a width of 8 mm to prepare a video tape. did.

Example 3 In synthesizing a polyether ether fluorinated ester, CH
CH ₃ (CH ₂ ) ₃ OCH ₂ CH ₂ OCH ₂ CH ₂ C instead of 30 parts of ₃ OCH ₂ CH ₂ OCH ₂ CH ₂ COOH
Polyether-based fluorinated ester B was obtained in the same manner as in Example 1 except that 38 parts of OOH was used. A video tape was produced in the same manner as in Example 1 except that this polyether fluorinated ester B was used as the lubricant component.

Example 4 A video tape was produced in the same manner as in Example 2 except that the polyether fluorinated ester B obtained in Example 3 was used as the lubricant component.

Example 5 In synthesizing a polyether ether fluorinated ester, CF was used.
Instead of 80 parts of ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ OH, CHF ₂ (C
Except for using F _{2) 5} CH ₂ OH 74 parts, polyether in the same manner as in Example 1 - was obtained ether-based Hutu fluorinated ester C. As a lubricant component, this polyether fluoroester C
A video tape was produced in the same manner as in Example 1 except that was used.

Example 6 A video tape was produced in the same manner as in Example 2 except that the polyether fluorinated ester C obtained in Example 5 was used as a lubricant component.

Comparative Example 1 In synthesizing a polyether ether fluorinated ester, CH
_A fluorinated ester D was prepared in the same manner as in Example 1 except that 40 parts of CH ₃ (CH ₂ ) ₁₀ COOH (lauric acid) was used instead of 30 parts of ₃ OCH ₂ CH ₂ OCH ₂ CH ₂ COOH. Obtained. A video tape was produced in the same manner as in Example 1 except that this fluorinated ester D was used as the lubricant component.

Comparative Example 2 A video tape was produced in the same manner as in Example 2 except that the fluorinated ester D obtained in Comparative Example 1 was used as a lubricant component.

COMPARATIVE EXAMPLE 3 CF was used in the synthesis of a polyester-based fluorinated ester.
Instead of 80 parts of ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ OH, CH ₃ (CH
An aliphatic ester E was obtained in the same manner as in Example 1 except that 29 parts of ₂ ) ₃ CH (C ₂ H ₅ ) CH ₂ OH (2-ethylhexyl alcohol) was used. A video tape was produced in the same manner as in Example 1 except that this aliphatic ester E was used as the lubricant component.

Comparative Example 4 A video tape was produced in the same manner as in Example 2 except that the aliphatic ester E obtained in Comparative Example 3 was used as a lubricant component.

Comparative Example 5 A video tape was produced in the same manner as in Example 1 except that the lubricant component was not mixed in the magnetic paint.

Comparative Example 6 A video tape was produced in the same manner as in Example 2 except that the lubricant component was not applied by dipping onto the surface of the ferromagnetic metal thin film.

The friction coefficient of each of the video tapes obtained in Examples 1 to 6 and Comparative Examples 1 to 6 was measured in the following manner, and the actual running durability (repeated running durability) and still durability were measured. Was tested. The results of these tests are shown in Table 1 below.

<Friction coefficient> Surface roughness 0.2 s, outer diameter 4 mm
Wrap a video tape around a cylindrical pin of at a wrap angle of 150 degrees, apply a load of 21 g, and feed at a feed rate of 1.4 cm / sec.
The same place was repeatedly measured to obtain the friction coefficient at the 100th time.

<Actual Running Durability> A video tape was mounted on a video deck, a video signal was recorded, and the video signal was repeatedly run in a reproduction state, and the number of times the reproduction output was reduced by 3 dB from the initial value was measured. ..

<Still Durability> A video tape was mounted on a video deck, a video signal was recorded, and the time required for the reproduction output in the pose state to decrease by 6 dB from the initial value was measured.

[0039]

[Table 1]

Next, each of the video tapes obtained in Examples 1 to 6 and Comparative Examples 1 to 6 was tested for 8-mode sheer durability. The test method is a recorded video tape.
Take a 13m track, and use it to "fast forward → fast forward search → rewind search → (play) pose → fast forward search → (record)
A series of operations of "pose → fast forward → rewind" are repeated as one pass, and 100 passes, 200 passes, 3
The reproduction output was measured every 00 passes, 400 passes, and 500 passes, and the output reduction value with respect to the initial output was measured. The results are shown in Table 2 below.

[0041]

[Table 2]

As is clear from Tables 1 and 2, the video tapes of the present invention (Examples 1 to 6) have a friction coefficient higher than that of the conventional video tapes (Comparative Examples 1 to 6). It is small and has good running durability and still durability.
The mode shuttle durability is remarkably good, which shows that the magnetic recording medium of the present invention is particularly excellent in running property and durability.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a magnetic layer made of a ferromagnetic metal as a magnetic material on a non-magnetic substrate, the carbon layer having an ether bond in the molecular chain on the surface or inside of the magnetic layer. A magnetic recording medium comprising an ester of an acid and a partially fluorinated alcohol.