JPH04178357A - Fluorine-containing compound and preparation thereof and lubricant composition containing fluorine-containing compound and magnetic recording medium - Google Patents

Abstract

NEW MATERIAL:A compound of formula I (Rf is 6-50C fluoroalkyl ether; R is aliphatic alkyl, aliphatic alkenyl). USE:The compound of formula I expresses a good lubricating performance due to the synergistic effects of the respective terminal groups under all environments including severe low humidity environments. The formation of a lubricant layer containing the compound on the metal thin film of a metal thin layer type magnetic recording medium directly or through a protecting layer permits to impart good durability to the recording medium. PREPARATION:A fluorine-containing alkylamide ester of formula II is reacted with the tetrahydrofuran solution of a borane tetrahydrofuran complex, followed by reducing the carbonyl group of the reaction product to provide the compound of formula I.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a novel fluorine-containing lubricant useful as a lubricant, a surfactant, a mold release agent, a rust preventive agent, etc. for precision machines and precision parts that require high-precision lubrication. The present invention relates to a compound, a method for producing the same, a lubricant composition containing the fluorine-containing compound, and a magnetic recording medium such as a magnetic tape or a magnetic disk in which the fluorine-containing compound is contained in a lubricant layer.

BACKGROUND OF THE INVENTION As mechanical devices and parts become smaller and more precise, the type of lubrication in their sliding parts has shifted from fluid lubrication to boundary lubrication. In particular, in electronic devices and electronic components such as VTR1 magnetic disks, the use of ferromagnetic metal thin films to improve recording density provides highly accurate lubrication for the sliding movement between magnetic tapes, magnetic disks, and magnetic heads. It has become necessary.

For example, in vapor deposited tapes and hard disks, in order to minimize spacing loss between the magnetic recording medium and magnetic head while ensuring durability and practical reliability, a lubricant layer on the surface of the magnetic layer is required. is formed so that it is only a few tens of people thick.

Therefore, the materials for forming this lubricant layer are:
In particular, the development of organic compounds with excellent lubrication performance is an important issue.

As lubricants for metal thin film magnetic recording media, many fluorocarbon-based lubricants have been proposed because those with fluorocarbon chains in their molecules have excellent compatibility with metal thin films (for example, Kaisho 61-107527
No. 61-107528, JP-A-61-107528, JP-A-61-107528
-107529, JP 62-92225, JP 62-92226, JP 62-922
Publication No. 27). Additionally, compounds comprising perfluoroalkyl polyether chains have been proposed as lubricants for magnetic recording media (for example, U.S. Pat. No. 3,778.
(Specification No. 308, Japanese Unexamined Patent Publication No. 109028/1983).

On the other hand, those having a molecular structure similar to the fluorine-containing compound of the present invention include CF and CF3R.

l ll 03F70+CFCF20→, CFCONRzCOO
l([In the formula, R1 represents hydrogen or an aliphatic alkyl group having 1 to 12 carbon atoms, R2 represents an aliphatic alkylene group having 1.2 or 5 carbon atoms, and n represents an integer of 0 to 8. ] has been proposed as a surfactant.

(U.S. Pat. No. 3,798,265).

A method for producing a compound similar to the fluorine-containing compound of the present invention is proposed in JP-A-64-26539 as a method for producing a polyfluorinated compound. Specifically, polyfluorinated amino alcohol or The goal is to obtain the ester.

Problems to be Solved by the Invention Lubricant for metal thin film magnetic recording media strongly adheres to the surface of the metal film or protective film and the surface of the magnetic head, forming a coating layer of lubricant on those surfaces. It is important that the lubricant molecules are easily sheared at the contact point of the layers, that is, the sliding surface between the magnetic recording medium and the magnetic head. By the way, perfluoroalkyl polyether, which is conventionally known as a lubricant for magnetic recording media, has good intermolecular shearing properties because almost all of its molecular surface is covered with fluorine atoms, but the polarity of the molecules Since the magnetic head is weak, the adhesion force between the metal thin film surface or protective film surface and the magnetic head surface is weak. In order to improve this drawback, it has been proposed that various polar groups are introduced into the molecular terminals of perfluoroalkyl polyether, but the molecular weight of the perfluoroalkyl polyether is 3.
．． If the molecular weight is more than 000, the effect of introducing a polar group cannot be obtained much, and if the molecular weight is reduced to enhance the effect of the polar group,
The small interaction between perfluoroalkyl polyether molecules results in loss of lubricant due to its own evaporation. In other words, perfluoroalkyl polyethers and their end group-modified products have poor adhesion and stability to metal thin film surfaces, protective film surfaces, and magnetic head surfaces, and as a result, these compounds cannot be used for metal thin film magnetic recording media. The lubricant used has durability and reliability, especially the adhesion of magnetic metal to the magnetic head.
There was a problem with performance in low humidity environments where it is likely to occur on the surface.

On the other hand, the fluorocarbon-based lubricant described in the above-mentioned prior document has excellent compatibility with metal thin films and has been applied to metal thin film magnetic recording media; There was a problem in that sufficient durability could not be obtained at the bottom.

As a result of various studies taking the above points into consideration, we found that a fluorine-containing compound having a fluoroalkyl ether end group, an aliphatic hydrocarbon end group, and a specific polar end group in the same molecule is a suitable lubricant for metal thin film magnetic recording media. We have reached the conclusion that it is the best choice as a drug.

By the way, when the above-mentioned conventional method is used to produce the fluorine-containing compound of the present invention, a single fluorine compound cannot be obtained, but there is a problem in that three types of fluorinated compounds having different molecular structures are mixed. Was. Furthermore, in order to obtain a highly pure fluorinated compound, it is necessary to purify it using a silica column or the like, which poses a problem in that it increases costs.

The present invention has been achieved based on the above-mentioned conclusion and a new manufacturing method, and provides a novel fluorine-containing compound and a lubricant composition containing the fluorine-containing compound, which impart good durability and reliability to metal thin film magnetic recording media. An object of the present invention is to provide a magnetic recording medium such as a magnetic tape or a magnetic disk in which a lubricant layer contains a fluorine-containing compound and a fluorine-containing compound thereof.

Means for Solving the Problems The present invention for achieving the above objects has the following configurations 1 to 4.

(1) General formula (I) [Wherein, Rf represents a fluoroalkyriether terminal group having 6 to 5 carbon atoms, and R represents an aliphatic alkyl terminal group or an aliphatic alkenyl terminal group. ] A fluorine-containing compound represented by

(2) General formula [■] [In the formula, Rf represents a fluoroalkyl ether terminal group having 6 to 50 carbon atoms, and R represents an aliphatic alkyl terminal group or an aliphatic alkenyl terminal group. A method for producing a fluorine-containing compound represented by the general formula [■], which comprises reacting a fluorine-containing alkylamide ester represented by the formula with a tetrahydrofuran solution of a porantetrahydrofuran complex to reduce a carbonyl group.

(3) A lubricant composition characterized by containing a fluorine-containing compound represented by the general formula ([]).

(4) In a magnetic recording medium in which a ferromagnetic metal thin film is formed on a non-magnetic support, at least a fluorine-containing compound represented by the general formula [■] is added directly or via a protective film to the ferromagnetic metal thin film. A magnetic recording medium characterized in that a lubricant layer containing one or more types is formed.

Examples of the terminal group of the fluorine-containing compound of the present invention include those shown below.

Aliphatic hydrocarbon terminal groups, that is, aliphatic alkyl terminal groups and aliphatic alkenyl terminal groups, include C,H2□1-CiH2m-, -Ch Hzk, +CHC,IH2,, -C,H2i1 (however, , k, 1 and m are integers of 8 or more, and n is an integer of 0 or 1 or more. If the total number of carbon atoms is 7 or less or 31 or more, the lubricity is not sufficient.

As the fluoroalkyl ether terminal group, F+C, F,
O-masu, C2F4CH2-Ch, O÷C, F40→
TseCF 20→-, -cp, co2-CF3
CF3 F+CFCF20→, CFCFIz-CF.

cp, 0+CFzCFO→] "←CF 20→, -cp
2C') l 2-CF3, CF, R CF, O÷CFCFzO+TCFCONC2H4-CF
+ □ Cc l F z O+CF z CF O-+T+C
F z O+-CF z CHz- (however, m is 1~
15. n represents an integer of 1 to 45, and R represents hydrogen or an aliphatic alkyl group having 1 to 12 carbon atoms. ) etc., and the total number of carbon atoms in these end groups is suitably 6 to 5 degrees (preferably 10 to 30); if the total number of carbon atoms is less than 5, the lubricity is not sufficient, and if the total number of carbon atoms is 51 or more, In this case, the effect of the polar end group is reduced.

Next, the method for producing the fluorine-containing compound of the present invention will be explained. The fluorine-containing compound of the present invention has the general formula [■]
The present invention can be produced by adding a THF solution of a borane THF complex to a tetrahydrofuran (THF) solution of a fluorine-containing alkylamide ester represented by the formula, and refluxing the solution to reduce the carbonyl group to form an amine. The above general formula [
■] The fluorine-containing alkylamide ester represented by
It was discovered that a single compound can be obtained with high purity and high yield because it shows high reactivity with borane THF complex.With this discovery, the fluorine-containing compound of the present invention can be manufactured at low cost on an industrial scale. It became possible.

The lubricant composition of the present invention includes a fluorine-containing compound represented by the general formula [1] alone or a mixture of these and other lubricants, and as the other lubricant, a fluorocarbon-based lubricant may be used. preferable. In particular, JP-A-6
1-107527, JP-A-61-107528, JP-A-61-107529, JP-A-62-
Those described in JP-A-92225, JP-A-62-92226, JP-A-62-92227, etc. are suitable. Furthermore, other known lubricants, rust preventives, etc. may also be used in combination.

The fluorine-containing compound represented by general formula [I] must be contained in the lubricant composition in an amount of 20% or more, preferably 30% or more, and if it is less than 20%, it is difficult to obtain the effects of the present invention.

Next, an example of a ferromagnetic metal thin film type magnetic recording medium in which a lubricant layer containing a fluorine-containing compound represented by the general formula [1] is formed will be described.

The lubricant composition is formed directly or via a protective layer on the magnetic layer of the ferromagnetic metal thin film type magnetic recording medium by a conventional wet coating method or a dry coating method such as vacuum deposition.

The amount of adhesion is 0.05 to 100 cm per 1 hole on the surface.
It is preferably present in a thin layer with a thickness of 0.1 to 50 cm.

Examples of the ferromagnetic metal thin film include Co and Co-Ni.

Co-Cr, Co-Fe, Co-Ni-Cr, Co-N
i-Fe, Co-Ni-P, Co-Ni-
Ta or a partially oxidized version thereof can be used, and these thin films can be formed by vacuum evaporation, sputtering, ion blasting, plating, or the like. Further, it is also possible to provide an underlayer of Cr, Ti, etc. if necessary, and the appropriate thickness of the ferromagnetic metal thin film including the underlayer is 500 to 5,000. On the surface of the ferromagnetic metal thin film, if necessary, a metallic protective layer such as Cr, W, NiP, etc., an inorganic protective layer such as 5iO3SiC, carbon, graphite, diamond-like carbon, fluororesin, silicone resin, epoxy resin, An organic protective layer or a composite protective layer made of polyamide resin, plasma polymerization product, radiation polymerization product, etc. can be formed.

Non-magnetic supports include oxides such as glass and ceramics, and AI! , alloys, and Ti alloys, or plastic layers such as polyester, polyimide, polyamideimide, polycarbonate, and polyacrylate. Furthermore, the surface may be coated with Co--P plating, polyimide coating film, etc., or may have microscopic, mountain-like, wavy, etc. protrusions, textured protrusions, etc., as required. As for the surface roughness of those supports, the maximum height Rmaχ is 50~
600 people is appropriate. Further, its shape can be selected from tape, film, sheet, disk, card, drum, etc. depending on the purpose.

Function The fluorine-containing compound of the present invention has a fluoroalkyl ether terminal group, an aliphatic hydrocarbon terminal group, and a specific polar terminal group in the same molecule, and has a molecular weight of several 100 to 3,000.
Since it is about 0, the effect of the polar end group is fully exhibited,
These polar terminal groups strongly adhere to the surface of the metal thin film or protective film and to the surface of the magnetic head. Further, the fluoroalkyl ether powder '4M is exposed on the surface, contributes to lowering the energy of the surface, and forms a non-adhesive surface. Furthermore, the aliphatic hydrocarbon end group is a flexible carbon-carbon bond chain, and
It exhibits good lubricity because it is oriented through moderate intermolecular interactions with the hydrocarbon chains of other adjacent molecules.

Therefore, due to the synergistic effect of these end groups, good lubrication performance is exhibited in all environments including harsh low-humidity environments, and the problem regarding the durability and reliability of metal thin film magnetic recording media is solved.

Examples Below, Examples 1 to 4 describe examples of fluorine-containing compounds and their manufacturing methods, and Examples 5 to 12 describe examples of magnetic recording media using lubricant compositions containing these fluorine-containing compounds. Let's be specific.

Example 1 2F-+CF (CF3) cFzO→TCF(CFz
) 91.4 g (0.10 mol) of a fluorine-containing secondary alkylamide ester represented by CONHC+aH37 and 300 d of anhydrous tetrahydrofuran (THF) were mixed into a 1! equipped with a stirring blade and a dropping funnel. After flowing dry high-purity nitrogen for 1 minute, 300 d of THF solution of IM borane THF complex was added dropwise over about 2 hours while stirring on a water bath at 15-20"C. The reaction was completed by continuing refluxing and stirring for 18 hours. After the reaction was completed, the reaction solution was cooled to 5~10°C and distilled water Lo
om was carefully added dropwise to perform hydrolysis. Next 6N
After adding 50 d of hydrochloric acid and heating the reaction solution to 85-90°C and distilling off THF in the atmosphere, 6N sodium hydroxide Loom was added dropwise over about 1 hour while continuing to reflux and stirring to remove the amine. isolated. The resulting reaction mixture was made into a chloroform solution, and this solution was repeatedly washed with distilled water until the pH reached 7, and then this solution was dried with anhydrous sodium sulfate.

Next, chloroform was distilled off and the reaction mixture was made into a benzene solution, which was then cooled to 5°C and unreacted fluorine-containing secondary
By removing the alkylamide ester raw material, the melting point is 80°
A white solid of C was obtained. This white solid was analyzed by infrared spectroscopy (I
R), GPC and organic mass spectrometry (FD-MS) revealed that it was a fluorine-containing compound represented by formula A containing no starting materials and by-products.

IR: Absorption peak of carbonyl group 1.640 cm-' disappeared GPC: Fluorine-containing secondary alkylamide ester raw material not detected FD-MS: Main peak at m/e 900 Example 2 Formula CF30÷CF zcF (CF z 100.0g of fluorine-containing secondary alkylamide ester represented by O Mokobahi CF2O-1-CF, CONHC14H29 (average molecular weight 1000.m, n is an integer from 1 to 9)
(0.10 mol) and anhydrous THF300- were collected in 12 flasks equipped with a stirring blade and a dropping funnel, and after flowing dry high-purity nitrogen gas for 1 minute, they were stirred on a water bath at 15-20"C. Meanwhile, 300 d of THF solution of IM's Balun THF complex was added dropwise over about 2 hours.

Subsequently, refluxing and stirring were continued for 18 hours to complete the reaction. After the reaction is completed, the reaction solution is cooled to 5-10°C,
Hydrolysis was carried out by carefully dropping 100ml of distilled water.

Next, 50% of 6N chlorine was added, and the reaction solution was heated to 85-90°.
The mixture was heated to a temperature of 100.degree. C. and THF was distilled off in the air, and then 6N sodium hydroxide (100.degree.) was added dropwise over about 1 hour while refluxing and stirring was continued to isolate the amine. The obtained reaction mixture was purified in the same manner as in Example 1, and the melting point was 55°C.
A white solid was obtained. This white solid is IR, (:.

It was found by PC and FD-MS to be a fluorine-containing compound represented by 2B containing no starting materials or by-products.

IR: Absorption peak of carbonyl group 1+640 cm-' disappeared GPC, fluorine-containing secondary alkylamide ester raw material not detected FD-MS: Main peak at m/e 890 Example 3 2F-+CJF60←-CZF4CONHC18H3S
A waxy semi-solid was obtained by the same manufacturing method as in Example 1 using a fluorine-containing secondary alkylamide ester having an average molecular weight of 2.740.n as an integer of 1 to 15 as a raw material. This waxy semi-solid is IR, GPC
And, by FD-MS, it was found to be a fluorine-containing compound represented by formula C containing no starting materials and by-products.

IR, absorption peak of carbonyl group 1.640 cm-' disappears GPC, fluorine-containing secondary alkylamide ester raw material not detected FD-MS; main peak at m/e 2,730 (blank below) Example 4 Formula CeLF20→ CF zCF (CF 3)0-+T
-+CF zo+T-CF zCONHC+oHz+(
Average molecular weight 1430. m and n are integers from 1 to 20)
A waxy semi-solid was obtained by the same manufacturing method as in Example 1 using the fluorine-containing secondary alkylamide ester represented by as a raw material. This waxy semisolid is IR, GP
C and FD-MS revealed that it was a fluorine-containing compound represented by the formula containing no starting materials or by-products.

■R: Absorption peak of carbonyl group disappeared at 1,640 cm-' CPC, fluorine-containing secondary alkylamide ester raw material not detected FD-MS; main peak at m/e 1,420 Example 5 Added to polyester film Granular projections with a gentle slope made of fine silica particles (average height 70 people, diameter 1
150 μm) are present on the surface of the polyester film, which has several protrusions per 100 μm on the surface, and which has minimized relatively large protrusions caused by fine particles caused by polymerization catalyst residue.
Steep mountain-like protrusions made of human silica colloid particles as a core and UV-cured epoxy resin as a binder are 1X per 151 m.
A non-magnetic substrate was formed so that 10' pieces were formed. A Co--Ni ferromagnetic metal thin film (Ni content: 20%, film thickness: 1000 mm) was formed thereon by continuous vacuum oblique evaporation in the presence of a trace amount of oxygen. The oxygen content in the thin film was 5% in atomic fraction.

After applying the fluorine-containing compound of the present invention or a mixture of the same and a conventionally known lubricant to this sample in an amount of 10 cm per 1M of the metal thin film surface, a lubricant layer was formed. A magnetic tape was produced by cutting the tape into a predetermined width. These tapes were hung on a commercially available video deck in an environment of 23°C and 15% RH, and the output characteristics were measured during repeated runs, and the number of runs until the RF output decreased by 3 dB from the initial value or the output began to fluctuate was determined. I asked for it. These results are shown in Table 1. The fluorine-containing compounds of the present invention used are shown in Table 1 with the above-mentioned Example numbers. An example in which a lubricant layer was formed from a mixture of the fluorine-containing compound of the present invention and a conventionally known lubricant was also described.

(The following is a blank space) Table 1 From Table 1, it can be seen that all the magnetic tape samples having a lubricant layer containing the fluorine-containing compound of the present invention are excellent in repeated running durability in low humidity. On the other hand, magnetic tape samples having a lubricant layer consisting only of a conventionally known lubricant have poor durability in low humidity, as shown in the comparative example.

Example 12 A plate with a thickness of 2 on the surface of an A2 alloy plate with a diameter of 95 and a thickness of 1.2
The nonmagnetic substrate was plated with a nonmagnetic N1-P alloy of 5 μm and had protrusions with an average roughness of 50 mm and a maximum height of 300 mm formed by texturing. On top of that, a Cr base layer with a thickness of 1.300 mm and a thickness of 60 mm was applied by sputtering.
Sample A is obtained by forming a Co--Ni ferromagnetic metal thin film with a thickness of 200 nm, and further forming a graphite protective layer with a thickness of 200 nm on top of it by sputtering. Sample B was prepared by forming a diamond-like carbon protective layer with a thickness of 50 mm by plasma CVD instead of the graphite protective layer. A lubricant layer was formed by separately applying the fluorine-containing compound of the present invention or a mixture of the same and a conventionally known lubricant to each of these samples in an amount of 10 cm/rrf of the surface of the protective layer. . These magnetic disks were subjected to a C3S durability test in a 23"C 15% RH environment, and the number of C5S at which the friction coefficient exceeded 1.0 or the C at the time of a head crash was measured.
Durability was evaluated based on the number of 3S cycles. These results are shown in Table 2.

The fluorine-containing compounds of the present invention used are shown in Table 2 with the above-mentioned Example numbers. An example in which a lubricant layer was formed from a mixture of the fluorine-containing compound of the present invention and a conventionally known lubricant was also described.

(The following is a blank space) Table 2 From Table 2, it can be seen that all the magnetic disk samples having a lubricant layer containing the fluorine-containing compound of the present invention have excellent C3S durability in low humidity. On the other hand, a magnetic disk sample having a lubricant layer consisting only of a conventionally known lubricant has poor durability in low humidity, as shown in the comparative example.

Effects of the Invention The fluorine-containing compound of the present invention has a unique structure having a fluoroalkyl ether end group, an aliphatic hydrocarbon end group, and an imino end group in the same molecule, and due to the synergistic hardening of these end groups, it can withstand harsh conditions. Demonstrates good lubrication performance in all environments, including low humidity environments.

Therefore, the fluorine-containing compounds of the present invention can be used not only alone, but also as a lubricant consisting of a mixture of them and conventionally known compounds, and furthermore, as a magnetic recording medium using them as a lubricant layer. Its industrial value is enormous.

Claims (4)

[Claims] (1) General formula [I] ▲Mathematical formulas, chemical formulas, tables, etc.▼[I] [In the formula, Rf represents a fluoroalkyl ether terminal group having 6 to 50 carbon atoms, and R represents an aliphatic alkyl terminal group or an aliphatic alkyl terminal group. Indicates an aliphatic alkenyl end group. ] A fluorine-containing compound represented by (2) General formula [II] ▲ Numerical formulas, chemical formulas, tables, etc. are included ▼ [II] [In the formula, Rf represents a fluoroalkyl ether terminal group having 6 to 50 carbon atoms, and R represents an aliphatic alkyl terminal group or an aliphatic alkyl ether terminal group. The group represents an alkenyl end group. General formula [I] characterized in that the fluorine-containing alkylamide ester represented by ] is reacted with a tetrahydrofuran solution of a borane tetrahydrofuran complex to reduce the carbonyl group.
A method for producing a fluorine-containing compound represented by (3) A lubricant composition containing a fluorine-containing compound represented by the general formula [I]. (4) In a magnetic recording medium in which a ferromagnetic metal thin film is formed on a non-magnetic support, at least a fluorine-containing compound represented by the general formula [I] is added directly or via a protective film to the ferromagnetic metal thin film. A magnetic recording medium characterized in that a lubricant layer containing one or more types is formed.