JPH08259501A - Lubricating material and magnetic recording medium produced by using the material - Google Patents

Abstract

PURPOSE: To obtain a lubricating material easily soluble in general-purpose organic solvents such as n-hexane, having excellent lubricating performance and thermal stability, free from environmental pollution and useful as a magnetic recording medium by using a triblock polymer containing fluoride block and non-fluoride block connected with each other in a specific connection manner. CONSTITUTION: This material is composed of a triblock polymer having a fluoride/non-fluoride/fluoride structure expressed by the formula [Rf is a fluorinated alkyl block; Rh is non-fluorinated block; Rf' is a fluorinated alkyl block; X is O, NH or NR (R is an alkyl)]. Preferably, the number of C atoms constituting the Rh block is >=6, the number of C atoms bonded with F and constituting the Rf block is >=4 and the number of C atoms free from bonded F is <=4. The triblock polymer can be produced e.g. by esterifying or amidating a dicarboxylic acid constituting the Rh block with alcohols or amines constituting the Rf and Rf' blocks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a lubricating substance which is easily dissolved in a general-purpose organic solvent such as n-hexane and has excellent stability such as thermal stability, and this lubricating substance as a lubricant. The present invention relates to a magnetic recording medium such as a magnetic tape and a magnetic disk used.

[0002]

2. Description of the Related Art In general, a ferromagnetic metal thin film type magnetic recording medium prepared by depositing a ferromagnetic metal or an alloy thereof on a non-magnetic support by vacuum deposition or the like is a coating type magnetic recording medium. Compared to the medium, it is easy to achieve high coercive force and thin film in the magnetic layer, and although it has excellent high-density recording characteristics, it does not use a tough binder resin, and the surface activity of the magnetic layer is good. Since the friction coefficient with the head is large, it is easily worn and damaged, resulting in poor durability and running performance.

Therefore, for example, Japanese Unexamined Patent Publication No. 60-854.
27, JP-A-62-161744, JP-A-62-2
36118, JP-A-62-256218, JP-A-2
-210615 and the like, various lubricants such as perfluoropolyether lubricants, carboxylic acid lubricants, and partially fluorinated carboxylic acid ester lubricants are used to make these lubricants ferromagnetic. It exists on the metal thin film,
It has been proposed to improve durability and runnability.

However, due to the speeding up of the traveling and the change in the shape of the magnetic head, the above-mentioned lubricant cannot satisfy the required performance. In particular, if a protective film such as a carbon film, a silicon oxide film or a chromium oxide film is provided on the surface of a ferromagnetic metal thin film, the compatibility between these protective films and the lubricant is poor, and the required performance cannot be exhibited. There were many. Further, in the case of a fluorine-based lubricant, when it is contained in the magnetic layer and is attached to the surface of the magnetic layer, it must be dissolved in a fluorine-based organic solvent, and operations such as coating, dipping and spraying must be performed. However, the above fluorine-based organic solvent is not preferable because it leads to environmental destruction such as ozone layer destruction.

On the other hand, the present inventors have found that, according to the fluorine-based lubricant having a specific molecular structure composed of a fluorinated compound-non-fluorinated compound-fluorinated compound triblock compound, compared with the above-mentioned conventional lubricants,
Not only can it exhibit excellent lubrication performance,
As a general-purpose organic solvent such as n-hexane can be used as a solvent, and there is no need to use a fluorine-based organic solvent that leads to the destruction of the ozone layer as in the conventional case, it is known that it can be handled as an environment-friendly lubricant. We are currently studying its practical application.

[0006]

However, in the fluorine-based lubricant composed of this type of triblock body, the chemical bond connecting the fluorinated compound and the non-fluorinated compound is easily thermally decomposed depending on the synthetic raw material. It is easy to chemically crack due to cracking or hydrolysis, etc., and it is difficult to stably exhibit excellent lubricating performance over a long period of time due to its poor stability such as thermal stability. I knew there were some difficulties.

The present invention overcomes these problems and obtains a lubricating substance which is excellent in terms of stability such as thermal stability as a triblock body having excellent lubricating performance and being environmentally friendly. The purpose of the present invention is to obtain a magnetic recording medium having improved durability and runnability by using as a lubricant.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above object, and as a result, by using a triblock body in which a fluorinated compound and a non-fluorinated compound are linked in a specific bonding manner, In addition, it is possible to obtain a practical lubricant with excellent lubrication performance and environmental friendliness as well as thermal stability, and by using it as a lubricant for magnetic recording media, durability can be improved. Further, they have found that a magnetic recording medium excellent in running property can be obtained, and have completed the present invention.

That is, the first aspect of the present invention is the following general formula; Rf: Fluorinated alkyl block Rh: Non-fluorinated block Rf ': Fluorinated alkyl block X: Fluoride-non-fluoride-fluoride represented by -O-, -NH- or -NR- (R is an alkyl group) The present invention relates to a lubricating substance characterized by comprising a triblock body. A second aspect of the present invention is a magnetic recording medium having a magnetic layer on one side or both sides of a non-magnetic support, wherein the lubricating substance according to the first aspect is used as a lubricant inside or on the surface of the magnetic layer. The present invention relates to a magnetic recording medium characterized by having.

[0010]

The structure and function of the present invention is a triblock compound used in the present invention, which is a dicarboxylic acid (HOO) which constitutes an unbroken block.
C-Rh-COOH) and an alcohol or amine [Rf-OH, Rf-N, which constitutes a fluoroalkyl block.
H ₂ or Rf-NHR (and Rf'-OH, Rf'
A -NH ₂ or Rf'-NHR)], by reacting esterified or amidated, it is obtained. The ester bond and the amide bond formed by this reaction are particularly stable thermally and chemically, and even if these bonds are cleaved, the produced dicarboxylic acid, fluorinated alcohol, or the like is contaminated. It can be used as a stable and safe lubricating substance with less risk of adverse effects such as corrosion on lubricating products.

On the other hand, for example, even with the same ester bond, a triblock compound linked by an esterification reaction of a diol constituting a non-fluorinated block and a monocarboxylic acid constituting a fluorinated alkyl block, or Even with the same amide bond, the triblock form linked by the amidation reaction of the diamine that constitutes the non-fluorinated block and the monocarboxylic acid that constitutes the fluorinated alkyl block is inferior in thermal stability, etc. Since the above-mentioned fluorinated monocarboxylic acid and the like produced in step 1 are highly corrosive, the adverse effect on the lubricated product cannot be ignored.

As described above, the triblock body used in the present invention can exhibit better lubrication performance as a stable and safe lubricating substance, as compared with the other triblock bodies as described above. In addition, the original advantage of the triblock, that is, the fluorinated alkyl blocks at both ends of the molecule are almost insoluble in general-purpose organic solvents, but the non-fluorinated blocks are highly soluble in general-purpose organic solvents, so the molecule as a whole It also has the advantage of exhibiting sufficient solubility in the above solvents.

In this triblock form, the non-fluorinated block (Rh) may have a carbon skeleton having a linear, branched or cyclic structure, and the carbon skeleton may be saturated or unsaturated. Further, not only in the alkyl chain, but having an element other than carbon in the main chain, for example,
It may be a polyester chain, a polyester chain, a polyamide chain, a polycarbonate chain or the like. The number of carbon atoms is preferably 6 or more in order to improve the solubility in organic solvents.

Further, fluorinated alkyl blocks (Rf, R
f ′) may have a linear, branched or cyclic carbon skeleton, the carbon skeleton may be saturated or unsaturated, and only a part of constituent carbons may be fluorinated. It may be one that has been processed. In order to obtain the unique lubricity of fluorine, the number of carbon atoms bonded to fluorine is preferably 4 or more. Further, the number of carbon atoms to which fluorine is not bonded is preferably 4 or less. Especially, the carbon located at the molecular end on the non-fluorinated block side is in a state where fluorine is not bonded (CH ₂ ) _n . And the number of n is 1 to
When it is 4, the influence of the electronegativity of fluorine is reduced and the thermal stability and hydrolysis resistance of the triblock body are further improved, which is desirable. If necessary, a functional group such as a hydroxyl group, a carboxyl group, an amino group, a halogen, a mercapto group, a sulfonic acid group, a phosphoric acid group or a salt thereof may be bonded to the molecular end of the fluorinated alkyl block.

The lubricating substance of the present invention comprises one or more of the above-mentioned triblocks as an active ingredient. When using the lubricating substance, if necessary, a fatty acid or a metal salt thereof, Fatty acid esters, aliphatic amides, aliphatic alcohols, monosulfides, paraffins, silicone compounds, aliphatic and fluorinated esters,
It may be used in a mixed system with other general lubricating substances such as perfluoropolyether and polytetrafluoroethylene.

The magnetic recording medium of the present invention has a magnetic layer on one side or both sides of a non-magnetic support, and a lubricating substance consisting of the triblock body having the above-mentioned structure as a lubricant is provided inside or on the surface of this magnetic layer. It is characterized by having. Here, in order to provide the above-mentioned lubricating substance inside or on the surface of the magnetic layer, the lubricating substance is dissolved in a general-purpose organic solvent such as hydrocarbon, alcohol, ketone, ether, etc. It may be applied or sprayed on the magnetic layer of the support and dried, or conversely, the magnetic layer may be dipped in the above solution and dried. Alternatively, a lubricant may be provided on the opposite side of the magnetic layer and transferred to the magnetic layer side. Furthermore, after providing the lubricant in this way, excess lubricant and the like may be washed with a solvent.

When the magnetic layer is composed of a ferromagnetic metal thin film, a carbon (diamond-like or amorphous-like) film, a silicon oxide film, a chromium oxide film, or other organic compound is formed on the thin film by vacuum deposition, sputtering, plasma, or the like. The protective film may be provided. In addition, a protective film containing fluorine, silicon, or the like may be provided. Further, this ferromagnetic metal thin film may have a slight amount of water attached to its surface, or may be coated with a rust preventive such as benzotriazole.

The amount of the lubricating substance deposited on the ferromagnetic metal thin film is preferably in the range of 0.5 to 20 mg / m ² with respect to the thin film surface. If it is too small, it will be difficult to attach it evenly to the thin film surface,
Still durability cannot be improved sufficiently. On the other hand, if the amount is excessive, the magnetic head and the ferromagnetic metal thin film may stick to each other, which is not preferable.

In the coating type magnetic recording medium, coating, spraying,
In addition to adhesion formation by dipping, etc., even if a lubricant is mixed in a magnetic paint using a general-purpose organic solvent and this is coated on a non-magnetic support, a magnetic coating film containing a lubricant can be formed. Good.
Further, the magnetic coating film may be again adhered and formed by coating, spraying, dipping or the like.

In the magnetic recording medium of the present invention, as the non-magnetic support, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyvinyl chloride or the like plastic, aluminum alloy, titanium. Alloys and the like are preferably used. The non-magnetic support may be in the form of tape, sheet, disk, card or the like, or may have a projection on its surface.

In the ferromagnetic metal thin film type magnetic recording medium, Co, Ni, F is formed on one surface or both surfaces of the above non-magnetic support.
e, Co-Ni, Co-Cr, Co-P, Co-Ni-
P, Fe-Co-B, Fe-Co-Ni, Co-Ni-
Fe-B, Fe-Ni, Fe-Co, Co-Pt, Co
Various ferromagnetic materials such as -Ni-Pt or those obtained by adding oxygen to these are formed into thin films by methods such as vacuum deposition, ion plating, sputtering and plating. The thickness of the ferromagnetic metal thin film thus formed is
Usually, it is good to be in the range of 0.03 to 1 μm.

In a coating type magnetic recording medium, a magnetic coating material containing magnetic powder and a binder resin is coated on one or both sides of the above non-magnetic support, and the thickness is usually 0.1 to 10 μm.
A magnetic coating film of about m is formed. The magnetic paint may optionally contain various conventionally known compounding agents such as a filler, an antistatic agent, a dispersant, and a colorant.

Magnetic powders include γ-Fe ₂ O ₃ and Fe ₃
O ₄ , iron oxide in an intermediate oxidation state between γ-Fe ₂ O ₃ and Fe ₃ O ₄ , Co-containing γ-Fe ₂ O ₃ , Co-containing γ-Fe ₃
Various conventionally known magnetic properties such as oxide magnetic powders such as O ₄ , CrO ₂ and barium ferrite, metal magnetic powders such as Fe, Co and Fe-Ni-Cr alloys, and nitride magnetic powders such as iron nitride. The powder is widely used. In the acicular magnetic powder, the average particle size (long axis) is usually about 0.2 to 1 μm, and the average axial ratio (average long axis diameter / average short axis diameter) is usually about 5 to 10. In the case of plate-like magnetic powder, the average major axis diameter is usually 0.0
It is preferably about 7 to 0.3 μm.

As the binder resin, for example, vinyl chloride-vinyl acetate copolymer, fibrin resin, polyurethane resin, polyester resin, polyvinyl butyral resin, polyacrylic resin, epoxy resin Any of those generally used as a binder resin for magnetic recording media, such as a phenol resin and a polyisocyanate compound, is preferably used.

In the magnetic recording medium of the present invention, in which the magnetic layer is formed only on one side of the non-magnetic support, a back coat layer may be provided on the opposite side. This back coat layer mixes and disperses non-magnetic powder such as carbon black and calcium carbonate with a binder resin such as vinyl chloride-vinyl acetate copolymer, polyurethane resin, fiber resin and organic solvent. Then, a coating material for the back coat layer is prepared, and the coating material is applied to the opposite surface side of the nonmagnetic support and dried to form the coating material.

The lubricating substance of the present invention can be used as a lubricant for various fields in addition to the above-mentioned lubricant for magnetic recording media, and also for paint resins (corrosion-proof lining, non-adhesive coating, weather-resistant paint). ), Fiber treatment agent (water repellent, oil repellent treatment), release agent, oil resistant paper, leveling agent, adhesive, fire extinguishing agent, defoaming agent, optical fiber (as sheath component), optical lens, medical polymer material It can also be used for

[0027]

As described above, in the present invention, by using the triblock body in which the fluorinated compound and the non-fluorinated compound are linked in a specific bonding mode, coating, dipping and spraying with a general-purpose organic solvent are used. It is possible to operate, etc., and there is no fear of causing harmful effects such as environmental damage due to the use of fluorine organic solvent
It is possible to provide an environment-friendly lubricating substance which is excellent in stability such as lubricating performance and thermal stability. Further, by using this as a lubricant for a magnetic recording medium, it is possible to provide a magnetic recording medium with improved durability and running properties.

[0028]

EXAMPLES Next, examples of the present invention will be described to more specifically describe. In the following, "parts" means "parts by weight".

Example 1 0.5 mol of decanedicarboxylic acid having carboxyl groups on both ends of the molecule and 2- (perfluorodecyl) ethano-
To a mixture with 1 mol of sulfuric acid, 5 mmol of sulfuric acid was added, and De
While the produced water was separated by an-Stark water separator, the reaction was carried out at 200 ° C. for 6 hours. Then, it is purified by recrystallization or distillation to obtain a triblock 1 represented by the following structural formula: F (CF ₂ ) ₁₀ CH ₂ CH ₂ OCO (CH ₂ ) ₁₀ COOCH ₂ CH ₂ (CF ₂ ) ₁₀ F. This was used as a lubricating substance.

Example 2 0.5 mol of sebacic acid chloride and 1H, 1H
-To 1.2 mol of pentadecafluorooctylamine and 1.2 mol of pyridine, 800 g of diethyl ether was added and reacted at 50 ° C for 12 hours. It is washed with an aqueous solution of sodium hydrogencarbonate and water in this order, and then diethyl ether is distilled off, followed by purification by recrystallization or distillation, and the following structural formula: F (CF ₂ ) ₇ CH ₂ NHCO (CH ₂ ) ₈ CONHCH A triblock body 2 represented by ₂ (CF ₂ ) ₇ F was obtained, which was used as a lubricating substance.

Example 3 1 mol of phosphorus tribromide was carefully added to 800 g of a diethyl ether solution of 1 mol of 1H, 1H-perfluoro-1-octanol and 1 mol of pyridine, and the mixture was refluxed for 6 hours. . After allowing to cool, the mixture was diluted with water to separate an organic phase, which was washed with an aqueous sodium hydrogen carbonate solution and dried over magnesium sulfate, and then the solvent was distilled off. The residue is purified by distillation, 1
H, 1H-perfluoro-1-bromooctane was obtained.

Next, this 1H, 1H-perfluoro-1
To 800 g of a diethyl ether solution containing 1 mol of bromooctane and 1 mol of pyridine, 1 mol of CH ₃ NH ₂ was gently added and reacted at 20 ° C. for 6 hours. Then, the mixture was diluted with water to separate an organic phase, which was washed with an aqueous sodium hydrogen carbonate solution and dried with magnesium sulfate, and then the solvent was distilled off. The residue was purified by distillation to give N-1H, 1H-pentadecafluorooctyl-N-methylamine: F (C
F ₂ ) ₇ CH ₂ N (CH ₃ ) H was obtained.

In place of 1H, 1H-pentadecafluorooctylamine, 1.2 mol of N-1H, 1H-pentadecafluorooctyl-N-methylamine was used, and the reaction and treatment were carried out in the same manner as in Example 2. Then, a triblock body 3 represented by the following structural formula: F (CF ₂ ) ₇ CH ₂ N (CH ₃ ) CO (CH ₂ ) ₈ CON (CH ₃ ) CH ₂ (CF ₂ ) ₇ F is obtained, This was used as a lubricating substance.

Comparative Example 1 Instead of decanedicarboxylic acid, 1,10-decanedio-
2-mol (perfluorodecyl)
Instead of ethanol, 1 mol of perfluoroheptanoic acid was used and reacted and treated in the same manner as in Example 1 to give the following structural formula: F (CF ₂ ) ₆ COO (CH ₂ ) ₁₀ OCO (CF ₂ ) ₆ F, a triblock body 4 was obtained, which was used as a lubricating substance.

Comparative Example 2 1-instead of 2- (perfluorodecyl) ethanol
The reaction and treatment were conducted in the same manner as in Example 1 except that 1 mol of octanole was used, and the compound was represented by the following structural formula: H (CH ₂ ) ₈ OCO (CH ₂ ) ₁₀ COO (CH ₂ ) ₈ H. A triblock body 5 was obtained, which was used as a lubricating substance.

Comparative Example 3 0.5 mol of decamethylenediamine was used in place of the acid chloride of sebacic acid, and acid chloride of perfluorooctanoic acid 1 was used in place of 1H, 1H-pentadecafluorooctylamine. 2 mol of the triblock compound 6 represented by the following structural formula; F (CF ₂ ) ₇ CONH (CH ₂ ) ₁₀ NHCO (CF ₂ ) ₇ F, was reacted and treated in the same manner as in Example 2. This was used as a lubricating substance.

Comparative Example 4 As a conventionally known fluorine-based lubricant A, a fluorinated ether compound having ester groups at both ends of the molecule (DEAL manufactured by Montecatini, Italy) was used and lubricated. It was made a sexual substance.

Lubricating substances consisting of the triblock bodies 1 to 6 of Examples 1 to 3 and Comparative Examples 1 to 3, and
The solubility and thermal stability of the lubricating substance composed of the fluorine-based lubricant A of Comparative Example 4 in a general-purpose solvent were examined by the following procedures. The results are as shown in Table 1 below.

<Solubility in general-purpose solvent> n as a general-purpose solvent
Using hexane, the lubricative substance was added little by little to this general-purpose solvent and well stirred, and those that were dissolved at 0.05 wt% or more were evaluated as ◯, and those less than that were evaluated as x.

<Thermal Stability> 1 g of the lubricating substance and 1 g of cobalt powder were mixed and heated at 100 ° C. for 24 hours, and when the lubricating substance thickened or turned yellow, a change was observed. Those that did not exist were evaluated as ○.

[0041]

[Table 1]

Example 4 Co was obliquely deposited on a polyethylene terephthalate film having a thickness of 10 μm in an oxygen gas atmosphere, and a ferromagnetic metal made of Co—O having a thickness of 0.15 μm was formed on the film. A thin film was formed. Next, R of 13.56MHz
Using F (Radio Frequency), a monomer
DLC (Diamond-like carbon) with a thickness of 20 nm is formed on the ferromagnetic metal thin film by plasma polymerization using ethylene as a gas and hydrogen as a carrier gas.
After forming a protective film, it was cut into a width of 8 mm.

Next, as the lubricant, the lubricous substance composed of the triblock body 1 obtained in Example 1 was used.
-A lubricant solution was prepared by dissolving it in hexane to a concentration of 0.1% by weight. A ferromagnetic metal thin film having the above DLC protective film is dipped in this lubricant solution, dried, and a video tape having a lubricant film made of the triblock body 1 on (the DLC protective film of) the ferromagnetic metal thin film. I made a cup.

Examples 5 and 6 As the lubricant, the triblock materials 2 obtained in Examples 2 and 3 were used.
Ferromagnetic metal thin film (DLC protective film) in the same manner as in Example 4 except that the lubricating substance consisting of 3 was used.
Two kinds of video tapes having a lubricant coating formed of triblock bodies 2 and 3 were prepared.

Comparative Examples 5 to 7 As the lubricant, the triblock bodies 4 to 4 obtained in Comparative Examples 1 to 3 were used.
Ferromagnetic metal thin film (DLC protective film) in the same manner as in Example 4 except that the lubricating substance consisting of 6 was used.
Three types of video tapes having a lubricant coating formed of triblock bodies 4 to 6 were prepared.

Comparative Example 8 As the lubricant, the fluorine-based lubricant A of Comparative Example 4 was used,
This was dissolved in 1,1,2-trifluoro-1,2,2-trichloroethane to a concentration of 0.1% by weight to prepare a lubricant solution. The ferromagnetic metal thin film (DLC of the ferromagnetic metal thin film was prepared in the same manner as in Example 4 except that the ferromagnetic metal thin film having the DLC protective film was immersed in the lubricant solution and dried.
A video tape having a lubricant film made of a fluorine-based lubricant A on the protective film was prepared.

Still durability of each of the video tapes of Examples 4 to 6 and Comparative Examples 5 to 8 was 20.
8 ° C VTR (EV-S900 made by Sony) under the condition of ℃ and 50% RH, the reproduction output is 6dB compared to the initial value.
The still time until the decrease was measured. The results are as shown in Table 2 below.

[0048]

[Table 2]

As is clear from Tables 1 and 2 above, Examples 1 to 3 using the triblock bodies 1 to 3 of the present invention
Compared to the lubricating substance of Comparative Example 4 using the conventional foot lubricant A, the lubricating substance of No. 3 has excellent solubility and thermal stability in general-purpose solvents, and was used as a lubricant. It can be seen that the video tapes of Examples 4 to 6 have much better still durability than the video tape of Comparative Example 8 using the conventional foot-type lubricant A.

On the other hand, the lubricating substances of Comparative Examples 1 and 3 using the triblocks 4 and 6 different from the present invention have excellent solubility in general-purpose solvents but poor thermal stability. In addition, the lubricating substance of Comparative Example 2 using the triblock body 5 different from the present invention has excellent solubility and thermal stability, but the video tape of Comparative Example 6 using this as a lubricant has a still durability. It turns out that it is extremely inferior in sex.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G11B 5/71 G11B 5/71 // C10N 40:18 (72) Inventor Kazushi Miyata Ibaraki, Osaka Prefecture 1-88 Ichira-Tora, Hitachi Maxell Co., Ltd.

Claims (4)

[Claims] 1. The following general formula; Rf: Fluorinated alkyl block Rh: Non-fluorinated block Rf ': Fluorinated alkyl block X: Fluoride-non-fluoride-fluoride represented by -O-, -NH- or -NR- (R is an alkyl group) Lubricating substance characterized by comprising a triblock body of. 2. The number of carbon atoms constituting Rh is 6 or more, the number of carbon atoms bound to fluorine constituting Rf is 4 or more, and the number of carbon atoms not bound to fluorine atom is 4 or less. Item 1 is a lubricious substance. 3. A magnetic recording medium having a magnetic layer on one side or both sides of a non-magnetic support, and the lubricant substance according to claim 1 or 2 as a lubricant inside or on the surface of the magnetic layer. A magnetic recording medium characterized by the above. 4. The magnetic recording medium according to claim 3, wherein the magnetic layer is made of a ferromagnetic metal thin film, and the surface of the thin film has a carbon film, a silicon oxide film or a chromium oxide film.