WO1998055464A1

WO1998055464A1 - Fluoropolyethers and use thereof

Info

Publication number: WO1998055464A1
Application number: PCT/JP1998/002405
Authority: WO
Inventors: Fumihiko Yamaguchi; Yoshitaka Honda
Original assignee: Daikin Industries, Ltd.
Priority date: 1997-06-03
Filing date: 1998-06-01
Publication date: 1998-12-10
Also published as: JP4192277B2

Abstract

Fluoropolyether compounds of general formula (I) wherein Rf's may be the same or different and each represents a group of the following general formula (II): X-(CH2CF2CF2O)a- (CHClCF2CF2O)b-(CCl2CF2CF2O)c- (CHFCF2CF2O)d-(CFClCF2CF2O)e- (CF2CF2CF2O)f-CF2CF2-, in which a, b, c, d, e and f each independently represents 0 or a positive integer satisfying 2∫a+b+c+d+e∫200 and a+d+f⊃1; and X represents hydrogen, fluorine or chlorine.

Description

Specification

Fluorinated polyether and its use

Technical field

The present invention relates to a lubricating oil having a fluorine-containing polyether terminal modified with a triazine, particularly a lubricating oil for a magnetic recording medium, and a magnetic recording medium having the lubricating oil.

Such lubricating oils provide excellent lubricity by firmly adhering to a substrate surface such as carbon, amorphous carbon, graphite, ceramics, and metal surfaces in a thin film state, and provide excellent lubrication of magnetic recording media. Demonstrate.

Background art

Magnetic recording media such as tapes, cards, and disks are required to have higher magnetic recording densities, and the sliding conditions between the magnetic recording head and the magnetic surface are becoming more severe. Specifically, the distance between the magnetic reading head and the magnetic recording surface has become smaller, and the sliding speed has been increasing. From the viewpoint of durability and practicability, it is used on the surface of a magnetic recording medium. There is a demand for improved performance of lubricants.

Conventionally, perfluoroethers have been used as lubricants for magnetic recording media, and are described, for example, in US Pat. No. 3,715,378.

These perfluoropolyethers have excellent heat resistance, chemical inertness, and low vapor pressure, and are excellent lubricants, but they themselves have poor adsorptivity to media, and as such, are suitable for magnetic recording media. Difficult to use as a lubricant.

Therefore, the end of perfluoropolyether is converted to a polar group in order to increase the adsorptivity of the lubricant to the medium, and the effect of the polar group causes the perfluoropolyether lubricant to adhere to the medium substrate. (U.S. Pat. No. 4,267,382, U.S. Pat. No. 4,685,556, Japanese Patent Application Laid-Open No. 61-24727, etc.).

The perfluoroalkylpolyester lubricant having a polar group at the end adsorbs onto the medium by the action of the polar group, and maintains lubricity by the perfluoropolyalkylene alkyl chain extending therefrom. ing.

However, the demand for lubricants for magnetic recording media has been further increased with the demand for remarkable improvement in magnetic recording density. Even in the case of these fluorophore ethers having polar groups, lubrication and lubrication properties have been practically required. Not enough durability ing.

In order to solve this problem, it is necessary to select an appropriate polar end group in order to have sufficient durability.

For example, Japanese Patent Publication No. 5-47599 discloses an attempt to use a perfluoropolyether lubricant having a pyridine ring, a pyrimidine ring, a triazine ring, etc. at its terminals as a lubricant for magnetic recording media. .

However, since the compound connects the triazine ring and the perfluoropolyether moiety with an amide bond, there is a problem in terms of hydrolysis and long-term use.

Compounds in which a triazine ring and a perfluoropolyester are directly connected by a C-C bond are described in, for example, U.S. Pat.No. 3,642,273.The perfluoro-mouth polyether used is a variety having a side chain. Yes, the coefficient of friction is high, and it cannot be said to be a good lubricant for magnetic recording media.

Disclosure of the invention

The present invention provides the following general formula (I):

[In the formula, Rf is the same or different, and has the following general formula (II)

X- (CH ₂ CF ₂ CF ₂₀ ) .- (CHClCF ₂ CF ₂₀ ) _h- (CCl ₂ CF2CF20) _c- (CHFCF ₂ CF ₂₀ ) _I) -

(CFC1CF ₂ CF ₂₀ ) (CF ₂ CF ₂ CF ₂₀ ) _f -CF ₂ CF _2- (ID

(In the formula (II), a, b, c, d, e, and f are each independently 0 or a positive integer, and a + b + c + d + e + 200 and a + d + ί > There is no particular restriction except for satisfying 1, but preferably 5 + a + b + c + d + e + 100, More preferably, it is 10 + a + b + c + d + e + 50. Preferably, a-b = d = 0. The order of the repeating units a to e is not limited in the formula. X is a force representing a hydrogen atom, a fluorine atom or a chlorine atom, preferably a fluorine atom. )]

And a lubricating oil containing the compound, a lubricating oil for a magnetic recording medium, and a magnetic recording medium.

As a particularly preferred structure of the compound represented by the above formula (I), for example, a compound represented by the following formula (III) can be exemplified.

[In the formula, n is a positive integer satisfying 2 to n and 200. ]

As long as a, b, c, d, e, f and n are within the above ranges, the compound of the present invention may be a mixture of compounds having different values of a to f and n. Therefore, for example, even if the value of a is a positive integer, the average value of a may not be an integer, and such a value is also within the scope of the present invention.

The compound (I) of the present invention can be produced, for example, according to the method described in US Pat. No. 3,654,273, Macromol. Chem. Phys. 195, 3137 (1994).

Specifically, it is synthesized as shown in the following reaction process formula 1>. The reaction process formula

The acid fluoride (Rf-CF ₂ C0F; R f is as defined above) used as a starting material in 1> is synthesized by the method described in EP 0 148 482. <Reaction process formula 1>

(1) Esterification

CHaOH

f -CFzCFzCOF-Rf -CF ₂ CF ₂ C0OCH ₂

ω (ii)

(2) Amidation

Rf-CF ₂ CF ₂ C00CH ₃ -Rf -CFzCFaCONHa

(ϋ) (iii)

(3) Nitorino Rei

P ₂ 0 _E

Rf -CF ₂ CF ₂ C0NH ₂ -Rf -CF2CF2CN

(iii) (iv)

(4) Cyclization

(V)

(Wherein, R f _{_{'is, X- (CE CF 2 CF 2}} 0) a - (CHClCF 2 CF 2 0) b - (CC1 2 CF 2 CF 2 0) C - (CHFCF 2 CF 2 0) d - (CFClCF ₂ CF ₂₀ ) _e- (CF ₂ CF ₂ CF ₂₀ ) _f-wherein X, a, b, c, d, e and f are the same as above.

(1) Esterification

The ester (ii) is obtained by reacting the acid fluoride (i) with methanol in the presence or absence of a base at a temperature from ice cooling to about room temperature. The reaction is acid fluor The reaction is carried out at room temperature for about 248 hours using about 1 mol of methanol and about 12 mol of base per 1 mol of the ride. Examples of the base include organic amines such as triethylamine. Examples of the reaction solvent include chloroform, benzene, and fluorine-based solvents.

(2) Amidation

The desired amide (iii) is obtained by reacting the ester (ii) with ammonia. The reaction is carried out at room temperature for about 248 hours using an excess amount of ammonia gas per mole of the ester (ii).

(3) nitrile conversion

The desired nitrile (iv) is obtained by reacting the amide (iii) with phosphorus pentoxide. In the reaction, phosphorus pentoxide is used in an excess amount per 1 mol of the amide (iii), and the reaction is carried out at a temperature of about 180.sup.204 C for 248 hours.

(4) Cyclization

The desired compound (V) having a triazine ring is obtained by reacting nitrile (iv) with ammonia gas in an autoclave. In the reaction, ammonia is used in excess of 1 mol of nitrile (iv), and the reaction is carried out at dry ice-methanol cooling to 160 ° C for 16 days.

The fluorinated polyether compound of the present invention can be prepared by, for example, dissolving the compound in a fluorinated solvent such as trichlorotrifluorophenol, perfluorohexane, or CFeC and spraying it on a magnetic material, or immersing the magnetic material body in a solution. A magnetic recording medium having a lubricating oil can be obtained according to a conventionally known method such as coating with a lubricant.

Examples of the magnetic recording medium include a hard disk and a flexible disk.

According to the present invention, a fluorinated polyether compound particularly suitable as a lubricating oil for a magnetic recording medium such as a hard disk can be obtained.

A magnetic recording medium using the fluorinated polyether compound of the present invention as a lubricating oil exhibits excellent durability.

The lubricating oil of the present invention is applied to the surface of a magnetic disk, for example, with a thickness of about 530 people. BEST MODE FOR CARRYING OUT THE INVENTION

Next, the present invention will be described specifically with reference to Examples and Comparative Examples, but it is needless to say that the present invention is not limited to these Examples.

Example 1

(1) Synthesis of methyl ester

1 kg of acid fluoride “F- (CF ₂ CF ₂ CF ₂₀ ) _n -CF ₂ CF ₂ -COF (average value of n = 10) is charged into a 2 L four-mouth 7 las] at 60 ° C. After completion of the reaction, the reaction mixture was poured into a separatory port, only the lower layer was separated, washed with pure water, dried over magnesium sulfate, and 850 g of the ester was added. Obtained.

By IR analysis, it was confirmed that the absorption at 1890 cm- ^{1 in} the acid fluorite completely disappeared, and that the absorption of ester appeared at 1780 cm- '.

(2) Amide synthesis

A 2-L four-necked flask was charged with 615 g of the methyl ester obtained in the above (1), and ammonia gas was bubbled at a flow rate of 50 ml / rain for about 1 hour with stirring at room temperature. Thereafter, the mixture was heated to an internal temperature of 50 to 60 ° C., excess ammonia gas was removed by bubbling nitrogen, and then methanol was removed by simple distillation under reduced pressure to obtain 604 g of an amide.

The 1 R analysis, absorption of NSOcnf ¹ carbonyl of the methyl ester of starting material completely disappeared, 1600cm- ', 1740cm- \ 3000~3500 ιΓ ι to Ami de specific absorption was confirmed that have emerged.

(3) Synthesis of nitrile

Four-necked flask 2 L, the (2) obtained in § Mi de 580 g, narrowing specification phosphorus pentoxide 2113G, and reacted with stirring under heating at one hundred and eighty to two hundred and four ^e C. After allowing to cool, 1 L of hexane was added to the perfluous mouth, decanted, and filtered naturally. Washing with water was performed twice, and hexane perfluoro was removed by evaporation to obtain 364.8 g of nitrizole.

By IR analysis,

It was confirmed that the absorption of the amide at 1740 cm- '. 3000-3500 cm- ¹ completely disappeared, and the absorption specific to nitrile appeared at 2300 cm- ¹ .

(4) Synthesis of triazine

A 100 ml autoclave was charged with 10 g of nitrinole, and the pressure was reduced under cooling with dry ice and methanol, and 4 g of ammonia was charged. After that, one 40 ° C The mixture was stirred for 4 hours while being cooled in a lye ice-methanol bath, and then stirred at room temperature under reduced pressure. Since the internal pressure was increased to 7.6 kgZcm ² , the gas was purged and the pressure was reduced using an aspirator. In this state, the mixture was stirred at 130 ° C for 3 days and subsequently at 160 ° C for 3 days. The mixture was allowed to cool to room temperature, extracted with hexane, washed with water, dried over sodium sulfate, and evaporated to give 8.59 g of an oil.

By IR analysis, disappeared absorption of 2300cm- ¹ of nitrile, it was confirmed that the newly 1550cm- ¹ to the "door triazine" specific absorption has appeared.

Example 2

Acid fluoride F- (CH ₂ CF ₂ CF ₂₀ ),-(CHFCF ₂ CF ₂₀ ) (CF ₂ CF ₂ CF ₂₀ ) _b -CF ₂ CF ₂ -COF (a = 2, b = 4, c = Synthesis was carried out under the same reaction conditions as in Example 1 (same scale, same charged amount of each reactant, same reaction temperature, same reaction time) except that 14) was used, and a target triazine compound was obtained. The yields of ester, amide, nitrile, and triazine were 750 g, 582 g, 350 g, and 7.59 g, respectively. Tri azine obtained in the final step, it was confirmed that the specific absorption "triazine" appears in the Example 1 and the same 155 ocnt ¹ by IR analysis.

Example 3

The hard disk having a carbon layer on the uppermost layer was immersed in a lubricant solution composed of a 0.1% by weight perfluorinated hexane solution of the fluorinated polyether obtained in Example 1 and taken out. Heat treatment was performed at C for 1 hour. The thickness of the formed lubricating film was 20 persons.

When a durability test was performed on a hard disk using a CSS tester, the coefficient of friction was less than 0.5 even after 100,000 operations.

Example 4

5S The hard disk was treated in the same manner as in Example 3 except that the fluorine-containing polyester obtained in Example 2 was used. The thickness of the lubricating film was 30 people.

When a hard disk was tested for durability using a CSS tester, the coefficient of friction after 100,000 operations was 0.53.

Comparative Example 1

Fluorine-containing polyether having no terminal triazine ring: F- (CF ₂ CF ₂ CF ₂ 0) „-CF ₂ CF3 (average value of n = 10)

A hard disk was processed in the same manner as in Example 3 except that the hard disk was used. The thickness of the lubricating film was 22.

When a hard disk was subjected to an endurance test using a CSS tester, the coefficient of friction exceeded 0.5 after 200 cycles, and the hard disk crashed when it exceeded 1000 cycles.

Comparative Example 2

Perfluoropolyethers with branches in the main chain:

The hard disk was processed in the same manner as in Example 3 except that (average value of 11 = 10) was used. The thickness of the lubricating film was 20 people.

When a hard disk was tested for durability using a CSS tester, the coefficient of friction exceeded 0.5 after 50,000 passes. The coefficient of friction after 100,000 cycles was 0.95.

Claims

The scope of the claims

1. The following general formula (I):

Wherein Rf is the same or different and has the following general formula (II)

X-(CH ₂ CF ₂ CF ₂₀ ) a-(CHClCF ₂ CF ₂₀ ) _b- (CCl ₂ CF ₂ CF ₂₀ ) _e- (CHFCF ₂ CF ₂₀ ) <

(CFClCF2CF ₂ 0) _e- (CF ₂ CF ₂ CF20) _f -CF2CF _2- (II)

(In the formula (,), a, b, c, d, e, and f are each independently 0 or a positive integer, and 2 a + b + c + d + e + 200, 5 ^ a + satisfies d + i> 1. represents a hydrogen atom, a fluorine atom or a chlorine atom.

A fluorine-containing polyether compound represented by the formula:

2. The following formula (III):

[In the formula, n is a positive integer satisfying 2 <n <200. ]

The fluorinated polyether compound according to claim 1, which is represented by the formula:

3lubricating oil _c containing the fluorine-containing polyether compound according to claim 1 or 2

4. The lubricating oil according to claim 3, wherein the lubricating oil is a lubricating oil for a magnetic recording medium.

5. A magnetic recording medium to which the lubricating oil according to claim 3 is applied. · The magnetic recording medium according to claim 5, wherein the magnetic recording medium is a hard disk. 6. The magnetic recording medium according to claim 5, wherein the lubricating oil has a thickness of 5 to 30 persons.