JPH05247200A - Fluorinated polyether and magnetic recording medium using this fluorinated polyether - Google Patents

Abstract

(57) Abstract: OBJECTIVE basic skeleton -C _n F _2n O- _(n is 1 to 18 integer) fluorination of molecular weight 500 to 10,000 polyether - -CON on at least one end of the ether (R ₁₎ R ₂ [R ₁ and R ₂ are any of an aliphatic hydrocarbon group, a hydrocarbon group having a hydroxyl group at the terminal, and a hydrocarbon group having a -OCOR ₃ group at the terminal (R ₃ is a hydrocarbon group)] A fluorinated polyether having a polar group and excellent in solubility in organic solvents and hydrolysis resistance is obtained, and the fluorinated polyether is used as a lubricant of a magnetic recording medium to improve running property and durability. [configuration] basic skeleton (n is 1 to 18 integer) -C _n F _2n O-molecular weight of 500 to 10,000 fluorinated polyether - -CON on at least one end of the ether (R ₁₎ R ₂ [R ₁ and R ₂ is an aliphatic hydrocarbon group, a hydrocarbon group having a hydroxyl group at the terminal, a hydrocarbon group having a —OCOR ₃ group at the terminal (R ₃ is a hydrocarbon group)] and a magnetic recording medium using a polar group having a polar group represented by

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorinated polyether and a magnetic recording medium using the fluorinated polyether. More specifically, the present invention relates to a fluorinated polyester excellent in solubility in an organic solvent and hydrolysis resistance. And a magnetic recording medium using the fluorinated polyether as a lubricant, which has good running property and durability and is excellent in long-term stability.

[0002]

BACKGROUND OF THE INVENTION Generally, perfluoroalkylpolyethers
Tell has been used in various applications as an excellent lubricant, for example, a magnetic coating consisting of magnetic powder, a binder component, an organic solvent and other necessary components is coated on a substrate such as a polyester film and dried, Alternatively, it is used for a magnetic recording medium made by depositing a ferromagnetic material on a substrate by vacuum deposition or the like, and reduces the friction coefficient of the magnetic layer that runs while contacting the magnetic head etc. to reduce wear. , Has improved running and durability.

However, perfluoroalkylpolyether has a drawback that it is easily separated from the surface of the magnetic layer due to insufficient chemical interaction with the surface of the magnetic layer. It has been attempted to provide a polar functional group such as a hydroxyl group or a carboxyl group to the terminal, but it is not possible to use perfluoropolyether.
Since many tellers are soluble only in freon-based solvents, they pose a serious problem in terms of both process cost and safety. Therefore, in recent years, the solubility in organic solvents has been improved, and as a perfluoropolyether having excellent solubility in organic solvents, a compound containing a primary long-chain aliphatic amide at the molecular end of perfluoropolyether. Is proposed. (JP-A-2-78016)

[0004]

However, the amide group in a compound containing a primary long-chain aliphatic amide at the molecular end of this perfluoropolyether tends to have a high viscosity because of a high hydrogen bond, and When used in a magnetic recording medium, the surface of the magnetic layer has catalytic activity and the temperature becomes high during sliding, so hydrolysis reaction is likely to occur and improvement in running property and durability is insufficient, resulting in long-term reliability. There is a problem in terms of sex.

[0005]

SUMMARY OF THE INVENTION The present invention has been made a result of various investigations in view of the above circumstances, -C _n F
_2n O-unit (however, n is an integer from 1 to 18)
At least one terminal of a fluorinated polyether having a basic skeleton of 500 to 10,000 and a general formula —CON (R ₁ ) R ₂ [wherein R ₁ and R ₂ are aliphatic hydrocarbon groups, It is any one selected from a hydrocarbon group having a hydroxyl group and a hydrocarbon group having a -OCOR ₃ group at the terminal (provided that R ₃ is a hydrocarbon group). ] A fluorinated polyether having a polar group represented by the following formula is obtained, and the solubility in an organic solvent and the hydrolysis resistance are sufficiently improved. Also,
By using this fluorinated polyether as a lubricant in a magnetic recording medium having a magnetic layer provided on one or both sides of a non-magnetic support, the running property and durability are sufficiently improved, and repeated running and still Under severe operating conditions such as the above, it is possible to achieve high reliability, which was difficult with the conventional method, for a long period of time.

In the present invention, the above fluorinated polyether having a polar group has an aliphatic hydrocarbon group or the like at at least one terminal, and therefore has good solubility in an organic solvent and is easy to use. Becomes In addition, since the portion of the amide group where the hydrogen atom is located is replaced by a bulky aliphatic hydrocarbon group, etc., the increase in viscosity is suppressed, and the hydrolysis reaction is difficult even at high temperatures. And
Since the basic skeleton is a fluorinated polyether having a molecular weight of 500 to 10,000, it has an excellent lubricating effect.

However, when this kind of fluorinated polyether is used as a lubricant in a magnetic recording medium, it has a good affinity with an organic solvent and a binder component and can be easily dispersed uniformly in a magnetic layer. .. In addition, interaction with the magnetic layer surface such as strong adsorption on the surface of the ferromagnetic metal thin film layer is also good, and the magnetic layer surface is well retained for a long period of time. Therefore, it can withstand strong sliding contact with the magnetic head, fully exhibit its excellent lubrication effect, sufficiently improve running performance and durability, and can be used for long periods under severe operating conditions such as repeated running and still. Stability is improved.

The fluorinated ether having such a polar group has, for example, a commonly available --C _n F _2n O-unit (n is an integer from 1 to 18) as a base skeleton and has at least one terminal. The fluorinated ether having a —COOH group has the general formula HN (R ₁ ) R ₂ (wherein R ₁ and R ₂ are aliphatic hydrocarbon groups).
Is synthesized by reacting an amine represented by Also preferred are those in which at least one of R ₁ and R _{2 in} the general formula is a hydrocarbon group having a hydroxyl group at the terminal, and those in which the terminal hydroxyl group is reacted with various carboxylic acids for esterification. Used and synthesized, this improves solubility in commonly used organic solvents.

Here, it is preferable that R ₁ and R ₂ have a large number of carbon atoms, and if the number of carbon atoms is small, the solubility of the fluorinated polyether in an organic solvent is poor. However, if the number of carbon atoms is too large, the melting point becomes high and the characteristics at low temperature may deteriorate. The aliphatic hydrocarbon group may contain a branched chain or an unsaturated bond. Further, the hydrocarbon group having a hydroxyl group at the terminal may be any of linear, branched, and cyclic hydrocarbon groups and may contain an unsaturated bond.

Thus, at least one of the terminals has --C
In order to use a fluorinated polyether obtained by reacting an fluorinated polyether having an OOH group and a molecular weight of 500 to 10,000 with, for example, an amine, as a lubricant for a magnetic recording medium, this kind of fluorine is used. Polyether is dissolved in an organic solvent such as methyl ethyl ketone, n-hexane, isopropyl alcohol and the like, and the magnetic layer is dipped in the solution obtained by this dissolution, or this solution is applied onto the magnetic layer or It is used by a method of spraying and depositing on the magnetic layer. Further, in addition to this, a fluorinated ether of this kind is mixed and dispersed with a magnetic powder, an organic solvent and other necessary components to prepare a magnetic coating, and the magnetic coating is sprayed onto a substrate such as a polyester film or Apply by any means such as roll coating,
It is also used in a method of forming a magnetic layer by drying.

When used as a lubricant for a magnetic recording medium, this kind of fluorinated polyether may be used alone as a lubricant, or may be used in combination with other conventionally known lubricants. , For example, aliphatic esters, fluorinated aliphatic esters, paraffins, silicone oil, fatty acids or metal salts thereof, fatty acid amides, aliphatic alcohols,
Monosulfide, paraffins, silicone compounds,
Resin powders such as perfluoropolyether and polytetrafluoroethylene are preferably used together.

When used as a lubricant for a magnetic recording medium, the amount of this kind of fluorinated polyether used is such that when it is deposited on the magnetic layer, the deposited amount is less than 0.05 mg / m ^2. The effect of the period is not obtained, and if it is more than 5.0 mg / m ² , it may cause output drop and dropout.
It is preferable to deposit within the range of mg / m ² . Also,
When it is contained in the magnetic layer, the desired effect cannot be obtained if the content is less than 0.1% by weight based on the magnetic powder.
If the amount is larger than the above range, the coating strength of the magnetic layer tends to deteriorate and the magnetic head may be easily soiled.

In the case of a ferromagnetic metal thin film layer, the magnetic layer is formed of Fe, Co, Ni, Co-Ni, Co-Cr, Fe.
-Ni, Fe-Co, Co-P, Co-Pt, Fe-C
o-B, Co-Ni-Fe-B, Fe-Co-Ni, C
A ferromagnetic material such as o-Ni-Pt or Co-Ni-P, or a ferromagnetic material containing a trace amount of a rare earth metal, is deposited on the substrate by means such as vacuum deposition, ion plating, sputtering and plating. The ferromagnetic metal thin film layer thus formed is formed by a method such as deposition.
The thickness is preferably within the range of 0.03 to 1 μm.

When the above-mentioned lubricant is applied to the ferromagnetic metal thin film layer thus formed, the ferromagnetic metal thin film layer may have a slight amount of water attached to its surface. -Although it may be coated with a rust preventive such as a rust-based material, or may be provided with a protective film layer made of an organic compound, carbon, silicon oxide or the like on the ferromagnetic metal thin film layer by vacuum deposition, sputtering, plasma or the like. Good.

For the magnetic layer, magnetic powder is mixed and dispersed with a binder resin, an organic solvent and other necessary components to prepare a magnetic paint, and the magnetic paint is applied onto a substrate such as a polyester film and dried. Is made.

In this case, the magnetic powder used is
γ-Fe ₂ O ₃ powder, Fe ₃ O ₄ powder, γ-Fe ₂ O ₃
Oxide powder in the intermediate oxidation state between Fe and O ₃ O ₄ , Co-containing γ-Fe ₂ O ₃ powder, Co-containing Fe ₃ O ₄ powder, CrO
_{In addition to 2} powders, various conventionally known magnetic powders such as metal powders such as Fe powder, Co powder, Fe-Ni alloy powder, Fe-Ni-Cr alloy powder, barium ferrite powder, and nitride-based magnetic powders such as iron nitride. Is widely used.

As the binder resin, vinyl chloride-
Vinyl acetate-based copolymers, fibrin-based resins, polyurethane-based resins, polyester-based resins, polyvinyl butyral-based resins, polyacrylic-based resins, epoxy-based resins, phenol-based resins, polyisocyanate compounds, etc. Any of those used as the binder resin of the magnetic recording medium is preferably used.

Further, as the organic solvent, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone,
Toluene, ethyl acetate, tetrahydrofuran, dioxane, dimethylformamide and the like which are generally used in magnetic recording media are used alone or in admixture of two or more.

In the magnetic coating composition, various commonly used additives such as abrasives, antistatic agents and dispersants may be optionally added.

A back coat layer may be provided on the back surface of a non-magnetic support having a magnetic layer formed on the surface thereof. This back coat layer contains a non-magnetic powder such as carbon black or calcium carbonate. A vinyl chloride-vinyl acetate copolymer, a urethane resin, a fibrin resin, etc., a binder resin and an organic solvent are mixed and dispersed to prepare a back coat layer coating material. It is formed by coating and drying on the back surface of a non-magnetic support having a magnetic layer formed on the surface.

As the non-magnetic support, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyvinyl chloride and other plastics, aluminum alloys and titanium alloys are preferably used.
The shape of the non-magnetic support may be any of tape, sheet, disk, card, etc., and may have protrusions formed on its surface.

[0022]

EXAMPLES Next, examples of the present invention will be described. Example 1 A polyethylene terephthalate film having a thickness of 10 μm was filled in a vacuum evaporation apparatus, and a Co—Ni alloy was heated and evaporated continuously under a residual gas pressure of 5 × 10 ⁻⁵ torr of oxygen gas to continuously evaporate the film. Is obliquely incident and vapor-deposited on a polyethylene terephthalate film to form Co-Ni-O (Co: Ni = 80: 2).
A 0.2 μm-thick ferromagnetic metal thin film layer of 0) was formed.

On the other hand, the general formula HOOC (CF ₂ O)
_m (CF ₂ CF ₂ O) _n CF ₂ COOH having an average molecular weight of about 2200, fluorinated polyether (manufactured by Montefluos; Fomblin Z-DIAC) and COOH groups in the fluorinated polyether. On the other hand, an equivalent amount of methyl stearylamine was mixed and reacted at 130 ° C. to obtain a fluorinated polyetheramide compound.

The fluorinated polyester thus obtained
The teramide compound was dissolved in isopropyl alcohol to obtain a 0.2 wt% isopropyl alcohol solution of the fluorinated polyether amide compound, and this solution was used as the ferromagnetic metal thin film layer formed on the polyethylene terephthalate film. It was coated on the surface and dried to form a protective layer made of a fluorinated polyetheramide compound. The coating amount of the fluorinated polyetheramide compound was 1.5 mg / m ² . Then, it was slit into a width of 8 mm to prepare a video tape.

Example 2 A ferromagnetic metal thin film layer was formed on a polyethylene terephthalate film in the same manner as in Example 1, and a 0.1% by weight benzotriazole isopropyl alcohol solution was applied onto the thin film and dried. .. The amount of benzotriazole deposited is 1 m
It was g / m ² or less. Then, the fluorinated polyether amide compound used in Example 1 and 1,1,2,2-tetrahydroperfluorooctyl linoleate were simultaneously dissolved in isopropyl alcohol to give a fluorinated polyether. A 0.2 wt% isopropyl alcohol solution of a mixture of a ter amide compound and 1,1,2,2-tetrahydroperfluorooctyl linoleate was obtained, and this solution was used in Example 1 0.2 of the teramide compound
A protective layer was formed in the same manner as in Example 1 except that a weight% isopropyl alcohol solution was used instead, and a video tape was prepared. The amount of fluorinated polyetheramide compound deposited was 1.5 mg / m ² , and the amount of 1,1,2,2-tetrahydroperfluorooctyl linoleate deposited was
It was 1.5 mg / m ² .

Example 3 Using the fluorinated polyetheramide compound obtained in Example 1, 100 parts by weight of α-Fe magnetic powder MR-110 (manufactured by Zeon Corporation; vinyl chloride resin) 15 〃 N-2309 (Nippon Polyurethane Industry Co., Ltd .; Polyurethane 10 〃 Resin) Carbon Black 1 〃 α-Al ₂ O ₃ 0.5 〃 Fluorinated Polyetheramide Compound 3 〃 Coronet L (Nippon Polyurethane Kogyo Co., Ltd .; Trifunctional Low Component 6 Mole amount isocyanate compound) A composition of cyclohexanone 150〃 toluene 150〃 was mixed and dispersed in a ball mill for 100 hours to prepare a magnetic paint. This magnetic paint was applied onto a polyethylene terephthalate film having a thickness of 11 μm and the thickness after drying was 3
A magnetic layer was formed by coating and drying so as to have a thickness of μm. Then, it was slit into a width of 8 mm to prepare a video tape.

Example 4 General formula HOOC (CF ₂ O) _m (CF ₂ CF ₂ O) _n
Fluorinated polyene having an average molecular weight of about 1000 represented by CF ₂ COOH
Ter, and an equivalent amount of di (2-ethylhexyl) amine to the COOH group in this fluorinated polyether, and a small amount of SnO as a catalyst are mixed and reacted at 130 ° C. to obtain a fluorinated polyether amide compound. It was Then, the fluorinated polyetheramide compound thus obtained was dissolved in methyl ethyl ketone to obtain a 0.2% by weight solution of the fluorinated polyether amide compound in methyl ethyl ketone. In this solution, polyethylene terephthalate was added in Example 1.
Dip the ferromagnetic metal thin film layer formed on the
After drying, a protective layer composed of a fluorinated polyetheramide compound was formed. The coating amount of the fluorinated polyetheramide compound was 1.5 mg / m ² . After that, 8mm
A video tape was produced by slitting the width.

Example 5 The same as Example 3 except that the same amount of the fluorinated polyetheramide compound obtained in Example 4 was used in place of the fluorinated polyetheramide compound in the composition of the magnetic coating material in Example 3. A video tape was produced in the same manner.

Example 6 General formula HOOC (CF ₂ O) _m (CF ₂ CF ₂ O) _n
Fluorinated polyene having an average molecular weight of about 2200 represented by CF ₂ COOH
Tell (made by Montefluos; Fomblin Z-DIA
C), N- (2-hydroxyethyl) dodecylamine in an amount equivalent to the COOH groups in the fluorinated polyether, and a small amount of SnO as a catalyst are mixed and reacted at 130 ° C. A teramide compound was obtained. Then, the fluorinated polyetheramide compound thus obtained was dissolved in methyl ethyl ketone to obtain a 0.2% by weight solution of the fluorinated polyether amide compound in methyl ethyl ketone. The ferromagnetic metal thin film layer formed above was dipped and dried to form a protective layer made of a fluorinated polyetheramide compound. The coating amount of the fluorinated polyetheramide compound was 1.5 mg / m ² . Then, it was slit into a width of 8 mm to prepare a video tape.

Example 7 Example 3 was repeated except that the same amount of the fluorinated polyetheramide compound obtained in Example 6 was used in place of the fluorinated polyetheramide compound in the composition of the magnetic paint in Example 3. A video tape was produced in the same manner.

Example 8 Fluorinated polyetheramide compound obtained in Example 6 and -OH in this fluorinated polyetheramide compound
An equivalent amount of capric acid to the group and a small amount of Sn as a catalyst
O was mixed and reacted at 130 ° C. to obtain a fluorinated polyetheramide compound. Then, the fluorinated polyetheramide ester compound thus obtained was dissolved in methyl ethyl ketone to obtain a 0.2% by weight solution of the fluorinated polyetheramide ester compound in methylethylketone. The ferromagnetic metal thin film layer formed on the terephthalate film was dipped and dried to form a protective layer made of a fluorinated polyetheramide compound. Fluorinated poly
The coverage of the telamide ester compound was 1.5 mg / m ² . After that, slit it to a width of 8 mm and videotape it.
I made a cup.

Example 9 In the composition of the magnetic coating material in Example 3, the same amount as in the fluorinated polyetheramide compound obtained in Example 8 was used in place of the fluorinated polyetheramide compound. A video tape was produced in the same manner as in 3.

Comparative Example 1 A fluorinated polyetheramide compound was prepared in the same manner as in Example 1 except that the same amount of stearylamine was used instead of methylstearylamine in the synthesis of the fluorinated polyetheramide compound in Example 1. Got Then, the fluorinated polyetheramide compound thus obtained was dissolved in isopropyl alcohol to obtain a 0.2 wt% isopropyl alcohol solution of the fluorinated polyetheramide compound. In the same manner as in Example 2, except that benzotriazole was applied in the same manner and applied on the dried ferromagnetic metal thin film layer and dried to form a protective layer of a fluorinated polyetheramide compound, a video tape was prepared. I made a cup. The coating amount of the fluorinated polyetheramide compound was 1.5 mg / m ² .

Comparative Example 2 In the formation of the protective layer on the ferromagnetic metal thin film layer in Comparative Example 1, 1,1,2,2-tetrahydroperfluorooctyl linoleate was further added to the amide compound of fluorinated polyether. At the same time dissolved in isopropyl alcohol,
Amide compounds of fluorinated polyethers and 1,1,2,2
A 0.2% by weight isopropyl alcohol solution of a mixture with tetrahydropa-fluorooctyl linoleate was obtained, which solution was used as a 0.2% by weight amide compound of the fluorinated polyether used in Comparative Example 1. A protective layer was formed in the same manner as in Comparative Example 1 except that the solution was used instead of the solution to prepare a video tape. The coating amount of the fluorinated polyetheramide compound was 1.5 mg / m ² ,
The deposited amount of 1,2,2-tetrahydroperfluorooctyl linoleate was 1.5 mg / m ² .

Comparative Example 3 In the composition of the magnetic coating material in Example 3, the same amount of the fluorinated polyether amide compound obtained in Comparative Example 1 was used in place of the fluorinated polyether amide compound. Form a magnetic layer in the same manner as
I made a cup.

Comparative Example 4 Example 4 was repeated except that the same amount of dodecylamine was used instead of di (2-ethylhexyl) amine in the synthesis of the fluorinated polyether having polar groups in Example 4.
A fluorinated polyetheramide compound was obtained in the same manner as in. Then, the fluorinated polyester thus obtained
The teramide compound was dissolved in methyl ethyl ketone to obtain a 0.2 wt% methyl ethyl ketone solution of the fluorinated polyether amide compound, and the ferromagnetic metal thin film layer formed on the polyethylene terephthalate film in Example 1 was immersed in this solution. After drying, a protective layer made of a fluorinated polyetheramide compound was formed. Fluorinated poly
The coverage of the tellamide compound was 1.5 mg / m ² .
Then, it was slit into a width of 8 mm to prepare a video tape.

Comparative Example 5 As in Example 3 except that the same amount of the fluorinated polyetheramide compound obtained in Comparative Example 4 was used in place of the fluorinated polyetheramide compound in the composition of the magnetic coating material in Example 3. A video tape was produced in the same manner.

Comparative Example 6 The same amount of 6-hydroxyhexylamine was used instead of N- (2-hydroxyethyl) dodecylamine in the synthesis of the fluorinated polyether having a polar group in Example 6. A fluorinated polyetheramide compound was obtained in the same manner as in Example 6. Then, the fluorinated polyetheramide compound thus obtained was dissolved in methyl ethyl ketone to obtain a 0.2% by weight solution of the fluorinated polyether amide compound in methyl ethyl ketone. Immerse the ferromagnetic metal thin film layer formed above, dry,
A protective layer made of a fluorinated polyetheramide compound was formed. The amount of fluorinated polyetheramide compound deposited is
It was 1.5 mg / m ² . Then, it was slit into a width of 8 mm to prepare a video tape.

Comparative Example 7 As in Example 3 except that the same amount of the fluorinated polyetheramide compound obtained in Comparative Example 6 was used in place of the fluorinated polyetheramide compound in the composition of the magnetic coating material in Example 3. A video tape was produced in the same manner.

Comparative Example 8 The fluorinated polyetheramide compound obtained in Comparative Example 6 and the -OH in this fluorinated polyetheramide compound.
An equivalent amount of capric acid to the group and a small amount of Sn as a catalyst
Fluorinated polyester is mixed with O and reacted at 130 ° C.
A teramide ester compound was obtained. Then, the fluorinated polyethylene amide ester compound thus obtained was dissolved in methyl ethyl ketone to give a fluorinated polyester.
A 0.2% by weight solution of the telamide ester compound in methyl ethyl ketone was obtained, and the ferromagnetic metal thin film layer formed on the polyethylene terephthalate film in Example 1 was immersed in this solution and dried to obtain a fluorinated polyether amide. A protective layer made of an ester compound was formed. Deposition amount of fluorinated polyetheramide ester compound is 1.5 mg / m ²
Met. Then, it was slit into a width of 8 mm to prepare a video tape.

Comparative Example 9 In the composition of the magnetic coating material of Example 3, the same amount as the fluorinated polyetheramide ester compound obtained in Comparative Example 8 was used in place of the fluorinated polyetheramide compound. A video tape was produced in the same manner as in 3.

Comparative Example 10 In the formation of the protective layer on the ferromagnetic metal thin film layer in Example 1, the 0.2% by weight isopropyl alcohol solution of the fluorinated polyetheramide compound was replaced with a hydroxy-modified perfluoropolyether at both ends. A protective layer was formed in the same manner as in Example 1 except that a 0.2% by weight Freon solution of Teru (Montefluos, Fomblin Z-DOL) was used to prepare a video tape. The amount of hydroxy-modified perfluoropolyether at both ends deposited was 1.5 mg / m ² .

COMPARATIVE EXAMPLE 11 In the formation of the protective layer on the ferromagnetic metal thin film layer in Example 1, 1, 2, 2, 3% by weight of the fluorinated polyetheramide compound was replaced with the isopropyl alcohol solution.
Of 2-tetrahydroperfluorooctyl linoleate
A protective layer was formed in the same manner as in Example 1 except that a 0.2% by weight Freon solution was used to prepare a video tape.
The amount of 1,1,2,2-tetrahydroperfluorooctyl linoleate deposited was 1.5 mg / m ² .

Comparative Example 12 In the formation of the protective layer on the ferromagnetic metal thin film layer in Example 2, the fluorinated polyethylene amide compound and 1,1,1,
Instead of a 0.2% by weight isopropyl alcohol solution of a mixture with 2,2-tetrahydroperfluorooctyl linoleate, per terminal hydroxy-modified perfluoropolyether (manufactured by Montefluos; Fomblin Z-DOL) Was used to form a protective layer in the same manner as in Example 2 except that a 0.2% by weight freon solution of hydroxy-modified perfluoropolyether at both ends dissolved in Freon FC-77 was used.
A video tape was made. The amount of hydroxy-modified perfluoropolyether modified at both ends was 1.4 mg / m ² .

Comparative Example 13 In the formation of the protective layer on the ferromagnetic metal thin film layer in Comparative Example 12, 1,1,2,2-tetrahydroperfluorooctyl linoleate was further added to both ends of the hydroxy-modified layer.
Fluoropolyether (manufactured by Montefluos Co .; Fomblin Z-DOL) and simultaneously dissolved in Freon FC-77 to give hydroxy-modified perfluoropolyether at both ends and 1,1,2,2-tetrahydroperfluorooctyl. A 0.2 wt% Freon solution of the mixture with linoleate was obtained and compared with the exception that this solution was used in place of the 0.2 wt% Freon solution of the hydroxy terminated perfluoropolyether used in Comparative Example 12. A protective layer was formed in the same manner as in Example 12 to prepare a video tape. The amount of hydroxy-modified perfluoropolyether on both ends was 1.4 mg / m ²
The amount of 1,1,2,2-tetrahydroperfluorooctyl linoleate deposited was 1.5 mg / m ² .

With respect to the video tapes obtained in the respective examples and comparative examples, the friction coefficient was measured in the following manner under the conditions of 20 ° C. and 50% RH, and the jitter characteristics, the actual running durability and the stillness were measured. Durability was tested.

<Friction coefficient> Surface roughness 0.2 s, outer diameter 4 mm
Wrap the video tape around the cylindrical pin of at a wrap angle of 150 °, 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.

<Jitter-characteristic> A video tape is loaded into a video deck to record and reproduce a video signal, the interval of the horizontal sync signal of 15.75 KHz of the reproduced signal is read, and the horizontal sync signal of 1 second at that time is read. The gap was measured by measuring the gap.

<Actual Running Durability> A video tape was loaded in a video deck, a video signal was recorded, 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 loaded in a video deck and reproduced in still mode, and the time required for the reproduction output level to drop to 1/2 of the initial output level was measured. The results are shown in Tables 1 and 2 below.

[0051]

[0052]

Next, the 8-mode shuttle durability was tested for each of the video tapes obtained in the above Examples and Comparative Examples. As a test method, a recorded video tape 13 m is taken, and this is recorded as "fast forward → fast forward search → rewind search →
A series of operations of "(playback) pose → fast-forward search → (recording) pose → fast-forward → rewind" is repeated as one pass, and 100 passes, 200 passes, 300 passes,
The reproduction output was measured every 400 passes and 500 passes, and the output reduction value with respect to the initial output was measured. Table 3 below
And Table 4 is the result.

[0054]

[0055]

[0056]

As is clear from Tables 1 to 4, the video tapes obtained by the present invention (Examples 1 to 9).
Are smaller in friction coefficient and smaller in jitter characteristics than the conventional video tapes (Comparative Examples 1 to 13).
The actual running durability is good, the still time is long, and the 8-mode shuttle durability is remarkably good. From this fact, the fluorinated polyether obtained by the present invention is soluble in an organic solvent and hydrolysis resistant. It can be seen that the magnetic recording medium obtained by using this fluorinated ether is excellent in running property and durability and is excellent in long-term stability.

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Claims (3)

[Claims] 1. A —C _n F _2n O— unit (where n is 1 to 18).
Is an integer up to. ) With a basic skeleton of 500
-CON (R ₁ ) R ₂ [wherein R ₁ and R ₂ are an aliphatic hydrocarbon group, a hydrocarbon group having a hydroxyl group at the terminal, or a terminal group] at least at one terminal of the fluorinated polyether of 10,000 to 10,000. Is a hydrocarbon group having a —OCOR ₃ group (wherein R ₃ is a hydrocarbon group). ] Fluorinated ether having polar group represented by 2. A magnetic recording medium having a magnetic layer provided on one surface or both surfaces of a non-magnetic support, wherein the basic skeleton is a —C _n F _2n O— unit (where n is an integer from 1 to 18). And the molecular weight is 500 to 10,000
Of at least one terminal of the fluorinated polyether of the formula -CON (R ₁ ) R ₂ [wherein R ₁ and R ₂ are an aliphatic hydrocarbon group, a hydrocarbon group having a hydroxyl group at the terminal, and a terminal- It is any one selected from a hydrocarbon group having an OCOR ₃ group (provided that R ₃ is a hydrocarbon group). ] A magnetic recording medium characterized by using a fluorinated polyether having a polar group represented by 3. The magnetic recording medium according to claim 2,
Further, a magnetic recording medium using an aliphatic ester or a fluorinated aliphatic ester as a lubricant at the same time.