FR2722604A1 - LUBRICANT AND MAGNETIC RECORDING MEDIUM CONTAINING SAME - Google Patents

Abstract

Disclosed is a lubricant for a magnetic recording medium which comprises an ester of a perfluoropolyether having a terminal hydroxyl group, and a partially fluorinated long chain carboxylic acid, represented by the formula: RfCH2 0COR1 or R1 COOCH2 RfCH2 OCOR1 where Rf and R1 denote respectively a perfluoropolyether group and a long chain hydrocarbon group, a long chain tertiary alkylamine of formula: (CF DRAWING IN BOPI) where Ra, Rb and Rc denote hydrocarbon groups of which at least one is a a long chain hydrocarbon group having 3 or more carbon atoms, a phosphoric ester, a phosphorous ester or a long chain carboxylic acid ester, as well as a magnetic recording medium having a magnetic metal thin film on the surface of which is such a lubricant.

Description

The present invention relates to a lubricant used for a web

  magnet or a magnetic disk, and a magnetic recording medium containing this lubricant. More particularly, the present invention relates to improvements in operating performance, abrasion resistance, and durability of a magnetic recording medium. In the field of magnetic recording, a magnetic recording medium is widely used in which magnetic powders, such as gamma iron oxide powders, dispersed in an organic binder,

  cover a non-magnetic substrate.

  On the other hand, in response to the growing demand for high density recording, a thin magnetic metal magnetic recording medium in which a magnetic metal material such as Co alone or a Co-Ni alloy is directly deposited by plating, sputtering, vacuum deposition or ion plating on a

  non-magnetic substrate such as a polyester film or a polyamide film.

  The magnetic thin magnetic metal magnetic recording medium has a number of advantages in that it is satisfactory not only with respect to the coercivity and the rectangular ratio and in that it exhibits superior electromagnetic conversion characteristics. in the

  short wavelength range, but also in that its magnetic layer

  The tick may be of reduced thickness, so that the demagnetization of

  or loss of thickness during reproduction is less important, while it is not necessary to incorporate an organic binder as a non-magnetic material in the magnetic layer and it is therefore possible to increase

  the density of the magnetic material.

  However, the magnetic thin magnetic metal type magnetic recording medium mentioned above is extremely satisfactory with respect to the smoothness of the surface of the magnetic layer, so that it has a larger effective contact area with the magnetic head or the parts of

  such as the guide rollers, so that its coefficient of friction

  is increased and therefore tends to experience agglutination (adhesion) which may result in poor performance or

low durability.

  To avoid these disadvantages, it has been envisaged to use different lubricants. Thus, it has been attempted to apply higher fatty acids or their esters on a magnetic layer of the magnetic recording medium for

  improve its operating performance or durability.

  However, extremely severe characteristics are required for the lubricants employed in a magnetic recording medium because of their properties, so that conventional lubricants can not be used.

  employees satisfactorily.

  In fact, a lubricant used for a magnetic recording medium must (i) have higher low temperature characteristics to maintain its pre-established lubricating effects in the cold regions, (ii) be applied in an extremely small thickness and yet have effects lubricants sufficient in view of the importance attached to the spacing between the magnetic head and the magnetic layer, and (iii) be able to withstand long-term storage or

  prolonged use while maintaining its lubricating effects.

  However, the higher fatty acids or their esters, which have been used so far, are likely to freeze and solidify at low temperatures, for example at 0 ° C or below, so that their lubricating function is lost, and they

  are also likely to have poor long-term sustainability.

  The present inventors have developed a lubricant which is prepared by

  addition of a long chain primary alkylamine to a perfluoropolyester ester

  Ether (Japanese Unexamined Published Patent Application (Kokai) JP-A-05-194 971 corresponding to U.S. Patent Application No. 147,549). Although a magnetic recording medium employing such a lubricant is satisfactory in practice, it tends to have a coefficient of friction which increases gradually during use, so that the magnetic tape can not slip smoothly when it is in contact with the sliding elements such as the guide rollers when the tape is operated a large number of times on a VCR. As a result, the band suffers

  low amplitude sliding movements that degrade the reproduced image.

  In addition, the band tends to overlap the guide rollers, which deteriorates. Thus, it is an object of the present invention to provide a lubricant, and a magnetic recording medium containing the lubricant, and which is capable of maintaining superior lubricity and lubricity effects under various conditions of use so as to improve performance of

  operation, abrasion resistance and durability of the recording medium

magnetic effect.

  In a first aspect, the present invention provides a lubricant having an ester of a perfluoropolyether having a terminal hydroxyl group and a partially fluorinated long-chain carboxylic acid represented by the formula: RfCH2OCOR1 or R1COOCH2RfCH20COR1 (1) where Rf is a perfluoropolyether group and R1 denotes a partially fluorinated long-chain hydrocarbon group, and a long-chain tertiary alkylamine represented by the formula: Rb Ra-N-Rc (2) mixed with the ester, o Ra, Rb and Rc are groups hydrocarbon compounds of which at least one is a long-chain hydrocarbon group having 3 carbon atoms

or more.

  In this first aspect, the present invention provides a magnetic recording medium having a thin magnetic metal film

  formed on a non-magnetic substrate, in which a lubricant as defined above

  above is held on the surface of the thin magnetic metal film.

  In a second aspect, the present invention provides a lubricant containing an ester of a perfluoropolyether having a terminal carboxyl group and a long-chain alcohol, represented by the formula: RfCH2COOR1 or R1OCOCHRfCH2, COOR1 (3) where Rf denotes a group perfluoropolyether and R1 denotes a long-chain hydrocarbon group, and a long-chain tertiary alkylamine represented by the formula: Rb Ra-N-Rc (4) mixed with said ester, where Ra, Rb and Rc are hydrocarbon groups, one of which at least denotes a long-chain hydrocarbon group having 3 carbon atoms

or more.

  In a third aspect, the present invention provides an ester-containing lubricant of a perfluoropolyether having a terminal carboxyl group of a partially fluorinated long-chain alcohol, represented by the formula: RfCH2COOR2 or R2-OCOCH2RfCH2, COOR2 (5) o Rf denotes a perfluoropolyether group and R2 denotes a partially fluorinated long-chain hydrocarbon group, and a long-chain tertiary alkylamine represented by the formula: Rb I Ra-N-Rc (6) mixed with the ester, o Ra, Rb and Rc are hydrocarbon groups of which at least one denotes a long-chain hydrocarbon group having 3 carbon atoms

or more.

  The magnetic recording medium having a thin magnetic metal film on a non-magnetic substrate according to the second aspect or the third aspect of the present invention contains a lubricant according to the second or third aspect of the present invention on the surface of the thin metal film. magnetic. In a fourth aspect, the present invention provides a lubricant containing an ester of a perfluoropolyether having a terminal hydroxyl group and a long-chain carboxylic acid, represented by the formula: RfCH2OCOR1 or R1COOCH2RfCH2-OCOR1 (7) where Rf denotes a perfluoropolyether group and R1 denotes a long-chain hydrocarbon group, and a long-chain tertiary alkylamine represented by the formula: Rb R-N-Rc (8) mixed with the ester, o Ra, Rb and Rc are hydrocarbon groups of which at least one denotes a long-chain hydrocarbon group having 3 carbon atoms

or more.

  In the fourth aspect, the present invention provides a magnetic recording medium having a thin magnetic metal film formed on a non-magnetic substrate, wherein a lubricant as defined above

  is held on the surface of the thin magnetic metal film.

  In the lubricant of the first aspect of the present invention, the alkyl group R 1 of the perfluoropolyether ester, as the main constituent, represented by the formula (1), can be chosen whatever its molecular weight, its branched structure, its unsaturated bonds or differences in isomeric structure or alicyclic structure. However, an R1 alkyl group is preferred

  having 6 or more carbon atoms for reasons of solubility.

  The perfluoropolyether having a terminal hydroxyl group, which enters

  in the constitution of the perfluoropolyether ester, may be a mono-structure

  functional or a polyfunctional structure, if desired.

  Examples of monofunctional structures include those of formulas (9) and (10): F (CF 2 CF 2 CF 2 O) n CF 2 CF 2 CH 2 OH (9) CF 3 [OCF (CF 3) CF 2] m (OCF 2) 1 CH 2 OH (10) An example of a polyfunctional structure comprises that corresponding to formula (11): HOCH2CF2 (OC2H4) p (OCF2) qOCF2CH2OH (11) In formulas (9), (10) and (11) above, 1, m, n, p and q denote

  whole numbers greater than or equal to 1. The chemical structure of perfluoro-

  polyether is not limited to those defined above.

  Although there is no particular limitation with respect to the molecular weight of the perfluoropolyether, it is preferably in the range of 600 to 000. If the molecular weight of the perfluoropolyether is too high, the effect of the group terminal is decreased, whereas if the molecular mass is too low,

  the proper effect of the perfluoropolyether group is decreased.

  On the other hand, the long-chain tertiary alkylamine which is added to the perfluoropolyether ester can also be chosen whatever the molecular weight, the number of carbon atoms, the branched structure, the presence or absence unsaturated bonds or aromatic rings or differences in isomeric structure or alicyclic structure. With regard to the coefficient of friction, it is preferable that one of the three hydrocarbon groups Ra, Rb and Rc is a linear hydrocarbon group having 10 or more carbon atoms and that the two remaining hydrocarbon groups are hydrocarbon groups.

  linear having not more than 2 carbon atoms.

  In the case of the lubricant of the first to fourth aspects of the present invention, a long chain tertiary alkyl amine and at least one ester selected from phosphoric acid esters, phosphorous acid esters and

  esters of the long-chain carboxylic acids are added to the perfluoro-

  polyether mentioned above. This makes it possible to obtain superior lubricating properties under different conditions of use and the prolonged maintenance of the

lubricating effects.

  The amount of long chain tertiary alkyl amine added is preferably from 0.01 to 100, in terms of mole ratio, based on the perfluoropolyether ester. The recording medium of the first to fourth aspects of the

  The present invention contains at least one of the lubricants mentioned above.

  The magnetic recording medium according to the present invention is

  a magnetic recording medium of the thin magnetic metal film type

  a magnetic film deposited on a non-magnetic substrate, for example

  example by vapor deposition. In such a magnetic recording medium

  tick type thin magnetic metal film, an underlying layer can

  be disposed between the non-magnetic substrate and the magnetic layer.

  There is no limitation on the non-magnetic substrate or the thin magnetic metal film in the magnetic recording medium and

  any of those known in the art may be employed.

  If a rigid substrate such as an AI alloy plate or a glass plate is used as a non-magnetic substrate, a surface film (skin) of oxide or a surface film (skin) of Ni-P may be formed on the surface of the substrate, for example by anodic application of oxide to harden the surface of the substrate. The thin magnetic metal film is formed as a continuous film by physical vapor deposition techniques such as plating, sputtering or vacuum vapor deposition. For example, a magnetic recording magnetic metal film in a plane consisting of metals such as Fe, Co or Ni, alloys based on Co and Ni, alloys based on Co, may be used as a thin magnetic metal film. and Pt, alloys based on Co, Pt and Ni, alloys based on Fe and Co, alloys based on Fe and Ni, alloys based on Fe, Co and Ni, alloys based on Fe, Ni and B, alloys based on Fe, Co and B or alloys based on Fe, Co,

  No and B, or thin Co and Cr based alloy films.

  In the case of magnetic recording metal films

  magnetized in a plane, it is possible to form a sub-layer beforehand.

  embedded image constituted by a non-magnetic material with a low melting point such as Bi, Sb, Pb, Sn, Ga, In, Ge, Si or Ti on a non-magnetic substrate and depositing a magnetic metallic material in a direction perpendicular to the material non-magnetic through the underlying layer, vacuum vapor deposition or cathodic sputtering to form a thin magnetic metal film to allow the non-magnetic low melting point material to diffuse into the thin magnetic metal film for eliminate orientation and to ensure isotropicness in a plan as well as to improve coercivity. If it is a question of constituting a hard disk, it is possible to form on the surface of the thin metallic magnetic film a hard protective film such as a film of carbon, a diamond-like or amorphous carbon film, a film of 'oxide

of chromium or SiO2 film.

  Among the methods by which the magnetic recording medium contains the lubricant is a method for applying a layer of lubricant to the surface of the thin magnetic metal film or the protective film. The quantity of lubricant applied is preferably from 0.5 to

  mg / m 2 and more preferably from 1 to 20 mg / m 2.

  To allow the lubrication effect to be maintained under the most severe conditions, it is possible to use an agent for extreme pressure in a mass ratio of 30: 70 to 70: 30. in contact with the metal in a boundary lubrication zone, the extreme pressure agent reacts with the metal surface under the resulting friction heat and produces a surface film (skin) consisting of a reaction product to prevent friction or abrasion. Any of the phosphorus-based extreme pressure agents based on

  sulfur, based on halogen, based on organometallic compounds or composites.

  Although the lubricant of the present invention can be used alone as a lubricant for the magnetic recording medium, it can also be

  used in combination with conventional lubricants.

  The lubricant can also be used in combination with rust inhibitors. Any of the routine rust inhibitors may be employed in combination with this type of magnetic recording medium. Phenols, naphthols, quinones, heterocyclic compounds containing oxygen atoms and heterocyclic compounds containing

  Sulfur atoms are examples of anti-rust agents.

  In addition to the thin magnetic metal film that forms the layer

  magnetic, it is possible to form a back layer or a sub-layer

  lying on the magnetic recording medium of the thin magnetic metal film type. The backing layer is formed by mixing in a resin binder carbonaceous powders for imparting electrical conductivity and a pigment

  inorganic to control surface roughness.

  According to the present invention, the lubricant mentioned above may be incorporated into the backing layer or may be applied as a backing layer.

  surface coating on the back layer.

  The addition of a long-chain tertiary alkylamine to a perfluoropolyether ester makes it possible to improve the lubricating properties of the lubricant,

  while its lubricating effects may persist for a prolonged period.

  When this lubricant is used as a lubricant for a magnetic recording medium, its excellent lubricating properties can be fully manifested in order to improve the operating performance, the

  durability and abrasion resistance of the recording medium.

  It will be understood that in the lubricant of the present invention, as a predetermined amount of a long chain tertiary alkyl amine is added to the perfluoropolyether ester, it is possible to obtain excellent lubricity under different operating conditions, while the lubricating effects persist for a long time. On the other hand, because the above lubricants are employed in the magnetic recording medium of the present invention, its coefficient of friction does not increase when it is used repeatedly in a VCR. In addition, it is possible to obtain a uniform and smooth sliding contact between the sliding elements such as the guide rollers and the strip even in the case of repeated use, in order to ensure excellent image reproduction quality. . In addition, the magnetic recording medium has superior abrasion resistance and superior durability and suffers only

limited damage.

  The present invention will now be illustrated in a more

  specifies with the aid of the following nonlimiting examples.

Example 1-1

  A long chain tertiary alkylamine has been added to an ester represented by the formula (12): RfCH2OCOR1 or R1COOCH2RfCH2OCOR1 (12) where Rf is a perfluoropolyether group and R1 is a partially fluorinated long chain hydrocarbon group to prepare the lubricant 1 1 shown in the following Table 1. Long-chain tertiary alkylamine was added in

  an equimolar amount relative to the perfluoropolyether.

TABLE 1

  N 'Rf Molecular Weight R1 Ra Rb Rc 1-1 F (CF2CF2CF2O) nCF2CF2 3500 C8F17C10H20 C18H37 CH3 CH3 1-2 F (CF2CF2CF2O) nCF2CF2- 3500 C7F15C16H32 iso-C18H33 CH3 CH3 1-3 F (CF2CFCF2F2O) nCF2CF2 3500 C 3 F 7 CH = CHC 8 H 16 C 18 H 37 CH 3 CH 3 1-4 F (CF 2 CF 2 CF 2 O) nCF 2 CF 2 OCF2) 1 650 C8F17CloH20 C18H37 CH3 CH3 1-7 CF3 (OCF (CF3) CF2) m (OCF2) 1650 C3F7CH = CHC8H16 C18H37 CH3 CH3 1-8 CF3 (OCF (CF3) CF2) m (OCF2) 1650 C7F15Cl2H2 CH2 = CHC16H32 CH3 CH3 1-9 CF3 (OCF (CF3) CF2) m (OCF2) 16 C8F17CloH20 C18H37 CH3 C2H5 1-10 CF2 (OC2F4) p (OCF2) qOCF2 2,000 C8F17Cl · oH20 C18H37 CH3 CH3 1-11 CF2 (OC2F4) ) (OCF2) gOCF2 2,000 C7F15Cl H20 C16H33 CH3 CH3 1-12 CF2 (OC2F4) p (OCF2) qOCF2 2,000 C12H25C10H2O C14H29 CH3 C2H5 1-13 CF2 (OC2F4) p (OCF2) QOCF2 2,000 C2F5C10H2O C10OH21 CH3 CH3 TABLE 1 (continued) N 'Rf Molecular Weight R1 Ra Rb Rc 1-14 CF2 (OC2F4) p (OCF2) qOCF2 2,000 C7F15C16H32 C18H37 CH3 CH3 1-15 CF2 (OC2F4) p (OCF2) qOCF2 2,000 (CF3) 2CF The lubricant 1-1 was applied to the surface of a magnetic layer of a magnetic recording medium of the type described in FIGS. 1 to 4, wherein the lubricant 1-1 was applied to the surface of a magnetic layer of a magnetic recording medium. thin magnetic film prepared by the conventional method, so as to obtain a 1-1 sample strip. To do this, a thin magnetic metal film consisting of 80% by weight of Co and 20% by weight of Ni was formed to a thickness of 200 nm by oblique vapor deposition in the form of a magnetic layer on a film

  of polyethylene terephthalate 10 .mu.m thick.

  Lubricant film 1-1 was dissolved in n-hexane and applied to the surface of the magnetic layer in a coating amount of 5 mg / m 2

obtain the sample strip 1-1.

  The coefficient of friction of the sample strip 1-1 before and after operation was measured in a standard environment. Sample strip 1-1 was used on a commercial VCR manufactured by SONY CORPORATION under the trademark EV-S900 for 5 min in 100 tests to determine the number of tests performed until the size of output is reduced by 3 dB and until it eventually appears

vibrations of the band.

  The results are shown in Table 2 below.

TABLE 2

  Coefficient of Friction Coefficient of Friction Number of Vibration Occurrence Tests of the Examples Before Operation After Operation Working Band 1-1 0.18 0.23> 100 No 1-2 0.17 0.24> 100 No 1-3 0.18 0.23> 100 non 1-4 0.20 0.25> 100 non 1-5 0, 19 0.23> 100 non 1-6 0.17 0.21> 100 non 1-7 0, 18 0.23> 100 no 1-8 0.19 0.24> 100 no 1-9 0.18 0.24> 100 no 1-10 0.18 0.23> 100 no 1-11 0.18 0 , 22> 100 no 1-12 0.18 0.23> 100 no 1-13 0.19 0.24> 100 no 1-14 0.18 0.23> 100 no 1-15 0.18 0.24 > 100 no 1-16 0.19 0.23> 100 no It can be seen from Table 1 that the application of lubricant 1-1 on the surface of the magnetic layer can prevent an increase in the coefficient of friction after operation. band and vibration of the tape during tape operation on a VCR, which ensures satisfactory performance. Examples 1-2 to 1-16 Sample strips 1-2 to 1-16 were prepared in the same manner as in Example 1-1, except that the combination of the ester and tertiary alkylamine The long-chain tertiary alkylamine was used in an equimolar amount and in a two-fold molar amount relative to the monofunctional perfluoropolyether and the perfluoropolyether having functional groups at both ends. ends, respectively. In other words, long-chain tertiary alkylamine has

  used in an equimolar amount for a hydroxyl group.

  The resulting 1-2 to 1-16 sample strips were checked for the same characteristics as for Example 1-1. The results are

  also shown in Table 2 above.

  Table 2 shows that with sample strips 1-2 to 1-

  16, it is possible to avoid an increase in the coefficient of friction after operation and to avoid the appearance of vibrations of the band when operating in a video recorder, and to obtain good performance of

  operation as in example 1-1.

  Comparative Examples 1-1 to 1-6 Comparative bands 1-1 to 1-6 were prepared using, instead of the combination of the ester and the long-chain tertiary alkylamine, only the perfluoropolyether and long-chain fluorinated carboxylic acid of the lubricant 1-1 used in Example 1-1 (Comparative Example 1-1), only the long chain tertiary alkylamine of the lubricant 1-1 (Comparative Example 1 2), the ester of Example 1-1 mixed with an equimolar amount of oleylamine as primary amine (Comparative Example 1-3), the ester of lubricant 1-6 of Example 1 When mixed with an equimolar amount of oleylamine as the primary amine (Comparative Example 1-4), the ester of the lubricant 1-10 of Example 1-10 mixed with a two-fold molar amount of oleylamine as a primary amine (Comparative Example 1-5) and

  not using lubricant (Comparative Example 1-6).

  Comparative bands 1-1 to 1-6 were checked for the same characteristics as in Example 1-1. The results are shown in Table 3 below.

TABLE 3

  Ex. Comp. Coefficient of Friction Coefficient of Friction Number of Vibration Occurrence Tests of the No. * Before Operation After Operation Working Band 1-1 0.25 0.33 76 No 1-2 0, 14 _ 2 No 1-3 0.20 0.38> 100 yes 1-4 0.19 0.39> 100 yes 1-5 0.18 0.37> 100 yes 1-6 0 (, 90 - 1 yes We can see from Table 3 that if only the ester or only the tertiary alkyl amine is used as a lubricant or if one does not use

  lubricant it is not possible to get good performance from

  If the long-chain primary alkylamine is added to the lubricant, the coefficient of friction after operation increases, while

  vibrations of the web during tape operation in a magnetos-

  cope. Using the sample strips of this example, the relationship between the amount of tertiary alkylamine added to the ester and the coefficient of friction was

examined.

  In other words, lubricants were prepared in which the amount of long chain tertiary alkylamine relative to the ester was varied in a range from 0.01 to 100 in terms of molar ratio and sample strips were

  have been prepared using these lubricants.

  The coefficient of friction of each sample band was measured in the same manner as in Example 1-1. The results are presented in the

table 4.

TABLE 4

  Coefficient of friction Coefficient of friction Molar ratio of amine before operation after operation

0.25 0.26

0.24 0.26

0.19 0.25

1 0.18 0.23

0.5 0.19 0.23

0.01 0.21 0.25

0 0.25 0.33

  On the other hand, lubricant 1-10 employed in Example 1-10 was prepared in the same manner as above and sample strips were prepared using the resulting lubricant to check the coefficient of friction of the lubricants. sample strips before and after operation. The results are

  presented in Table 5 below.

TABLE S

  Coefficient of friction Coefficient of friction Molar ratio of amine before operation after operation

0.24 0.28

0.22 0.27

0.19 0.25

2 0.18 0.23

1.0 0.19 0.240.01 0.22 0.27

0 0.26 0.32

  It can be seen from Tables 4 and 5 that, when the above ester is used as a lubricant in admixture with the long-chain tertiary alkyl amine in a molar ratio of 0.01 to 100, it is possible to prevent the coefficient dc

  friction to increase after operation.

  Examples 1-17 to 1-26 The lubricants 1-17 to 1-26 shown in Tables 6 and 7 were prepared by mixing the esters of lubricants 1-1 to 1-10 with a tertiary alkylamine long chain, an agent for extreme pressure based on phosphorus and a

  long chain carboxylic ester.

TABLE 6

  Lubricant Extreme Pressure Agent Ester Carboxylic i n * Ra Rb Rc Phosphorus Based Long Chain

  1-17 C18H37 CH3 CH3 (C12H25) 2POOH C17H35COOC2H5

  1-18 C18H37 CH C2H5 (C16H330) 3P C17H35COOC2H5

  1-19 iso-C18H37 CH3 CH3 (C12H25S) 3P C17H29COOC2H5 CH2 = CHC16H32 CH3CH3 (iso-C18H370) 3P C17H35COOC4H9

TABLE 7

  Lubricant Extreme pressure agent Ester carboxylic acid with n Ra Rb Rc long-chain phosphorus

  1-21 C18H37 CH3 CH3 (C12H2O) 3P C17H35COOC2H5

  1-22 C16H33 CH3 C2H5 (C12H2O) 2POH C17H35COOC2H5

  1-23 C14H29 CH3 CH3 (C12H25S) 3P C17H29COOC4H9

  1-25 C18H37 CH3 CH3 (C18H3O) 3P C17H29COOC4H9

  1-25 iso-C18H37 CH3 CH3 (C18H31S) 3P C17H35COOC2H5 CH2 = CHC16H32 CH3 CH3 (iso-C18H370) 3P C17H35COOC4H9 Using these lubricants 1-17 to 1-26, sample strips 1-17 to 1-26 were prepared in the same manner as in Example 1-1. The sample strips thus prepared were examined for the same characteristics as in Example 1-1. The sample strips were used in a VCR not only in a standard environment, but also under conditions of temperature of 40 C and humidity of 80% and at a temperature of -5C. The results are presented under

  form of Examples 1-17 to 1-26 in Tables 8 and 9.

TABLE 8

  Coefficient of Coefficient of Number of Tests Number of Tests Number of Tests of Friction Before Friction After Operation Functioning Operation Occurrence of Ex. Operating Function (Standard Environment) (40-C, 80%) (-5- C) band vibrations 1-17 0.21 0.27> 100> 100> 100 no 1-18 0.20 0.26> 100> 100> 100 no 1-19 0.21 0.26> 100> 100> 100 no 1-20 0.22 0.27> 100> 100> 100 no rJ CD

TABLE 9

  Coefficient of Coefficient of Number of Tests Number of Tests Number of Tests of Friction Before Friction After Operation Functioning Operation Occurrence of Ex. Operating Function (Standard Environment) (40 C, 80%) (-5 "C ) band vibrations 1-21 0.20 0.27> 100> 100> 100 no 1-22 0.20 0.26> 100> 100> 100 no 1-23 0.19 0.25> 100> 100 > 100 no 1-24 0.20 0.27> 100> 100> 100 no 1-25 0.20 0.27> 100> 100> 1 (0 no 1-26 0.22 0.27> 100> 100 > 100 no It is seen from Tables 8 and 9 that with Examples 1-17 to 1-26 it is

  It is possible to prevent the coefficient of friction from increasing after the function

  ment. It is also seen that satisfactory results have been obtained during operation in the variable environments mentioned above and that band vibrations have not occurred. Comparative Examples 1-7 and 1-8 Oleylamine was added as the primary amine in place of the long chain tertiary alkyl amine in lubricants 1-17 and 1-21 employed in Examples 1-17. and 1-21 to produce lubricants. Using these lubricants, comparative strips 1-7 and 1-8 were prepared from the same

as in Example 1-1.

  These comparative strips 1-7 and 1-8 were examined for the same characteristics as in Examples 1-17 to 1-26. The results are shown in Table 10 below as examples

Comparative 1-7 and 1-8.

TABLE 10

  Ex. Coefficient of Coefficient of Number of Tests of Number of Trials of Number of Trials of Comp. friction before operation after operation operation n operation operation (standard environment) (40-C, 80%) (-5 ° C) vibration of the belt 1-7 0.20 0.40> 100> 100> 100 yes 1-8 0.22 0.39> 100> 100> 100 yes N It can be seen from Table 10 that with Comparative Examples 1-7 and 1-8, the coefficient of friction after operation increases significantly.

  sensitive, while vibrations of the band appear.

  It can be seen from the above results that when a lubricant obtained by the addition of a long-chain tertiary alkyl amine is used to an ester of a perfluoropolyether having a terminal hydroxyl group and a long-chain carboxylic acid partially fluorinated in an amount of from 0.01 to 100 in terms of molar ratio and when a phosphoric ester, a phosphorous ester, an ester of a long-chain carboxylic acid or an agent for extreme pressure to the mixture is further added result, the magnetic strip undergoes a lower increase in the coefficient of friction after operation or less vibration than in the case where the ester or the amine is used alone or in the case where a primary amine is used in place of the long-chain tertiary alkylamine, while the operating performance of the

  band are also improved under different operating conditions.

Example 2-1

  An ester represented by the formula (13): RfCH2COOR1 or R1OCOCH2RfCH2COOR1 (13) wherein Rf and R1 respectively denote a perfluoropolyether group and a long chain hydrocarbon group, has been mixed with a tertiary alkylamine long chain to prepare a lubricant 2-1 shown in Table 11. The long chain tertiary alkylamine was mixed in an equimolar amount with respect to the perfluoropolyether.

TABLE 11

  N Rf Molecular Weight R1 Ra Rb Rc 2-1 F (CF2CF2CF2O) nCF2-CF2, 3500 C12H25 C12H25 CH3 CH3 2-2 F (CF2CF2CF2O) nCF2CF2- 3500 C14H29 C14H29 CH3 CH3

  2-3 F CF2 CF2 CF2 CF2 CF2 3500 C18H37 C18H37 CH3 CH3

  2-4 F (CF2CF2CF2O) nCF2CF2 3500 CF11 (cyclohexyl) C10H21 CH3 CH3 2-5 F (CF2CF2CF2O) nCF2CF2 3500 C24H49 C1 2H25 CH3 C2H5 2-6 CF3 (OCF (CF3) CF2) m (OCF2) 1650 C18H37 C18H37 CH3 CH3 2-7 CF3 (OCF (CF3) CF2) m (OCF2) 1650 C14H29 C14H29 CH3 CH3 2-8 CF3 (OCF (CF3) CF2) m (OCF2) 1650 CH2 = CHC16H32 C18H37 CH3 CH3 2-9 CF3 (OCF (CF3) CF2) m (OCF2) 650 iso-C18H37 CH2 = CHC16H32 CH3 CH3 2-10 CF2 (OC2F4) p (OCF2) qOCF2 2,000 C1 1H23 C18H37 CH3 CH3 2-11 CF2 (OC2F4) p (OCF2) qOCF2 2000 C13H27 C14H29 CH3 CH3 2-12 CF2 (OC2F4) p (OCF2) qOCF2 2,000 C13H27 C14H29 CH3 C2H5 2-13 CF2 (OC2F4) p (OCF2) qOCF2 2,000 C15H31 C16H33 CH3 CH3 TABLE 11 (contd.) Nu Rf Molecular Weight R1 Ra Rb Rc 2-14 CF2 (OC2F4) p (OCF2) gOCF2 2,000 C17H35 C18H37 CH3 CH3 2-15 CF2 (OC2F4) p (OCF2) qOCF2 2,000 iso-C7H35 C18H37 CH3 CH3 2-16 CF2 (0C2F4) p (OCF2) gOCF2 4000 C17H35 C18H37 CH3 CH3

  This lubricant 2-1 has been applied to the surface of a recording medium

  very magnetic type of thin magnetic metal film prepared by a

  conventional method, so as to obtain a 2-1 sample strip.

  In other words, a thin magnetic metal film consisting of 80% Co and 20% Ni was formed at a thickness of 200 nm by oblique vapor deposition on a film of polyethylene terephthalate with a thickness of / m. Lubricant 2-1 was dissolved in n-hexane and applied to the surface of the magnetic layer so that the amount applied was

  5 mg / m2, to prepare a 2-1 sample strip.

  The coefficient of friction of the sample strip 2-1 obtained was measured before and after operation in a standard environment. The sample strip was used 100 times for 10 min in a commercial VCR manufactured by SONY CORPORATION under the trademark EV-S900 to determine the number of test runs until the output quantity was reduced by 3 dB and until the appearance of vibrations of the band.

  The results are shown in Table 12 below.

TABLE 12

  Coefficient of Friction Coefficient of Friction Number of Vibration Occurrences of Ex. N Before Operation After Operation Working Band 2-1 0.19 0.23> 100 No 2-2 0.18 0.25> 100 No 2 -3 0.18 0.22> 100 no 2-4 0.21 0.25> 100 no 2-5 0, 19 0.24> 100 no 2-6 0.18 0.22> 100 no 2-7 0.18 0.24> 100 no 2-8 0.20 0.24> 100 no 2-9 0.20 0.25> 100 no 2-10 0.18 0.22> 100 no 2-11 0, 17 0.22> 100 no 2-12 0.19 0.24> 100 no 2-13 0.19 0.23> 100 no 2-14 0.18 0.21> 100 no 2-15 0.20 0 , 25> 100 no 2-16 0.19 0.24> 100 no It can be seen from Table 12 that by applying lubricant 2-1 to the surface of the magnetic layer, it is possible to prevent the coefficient friction after operation to increase and that no vibration of the band occurs during operation in a VCR, which guarantees satisfactory operating performance. Examples 2-2 to 2-16 Sample strips 2-2 to 2-16 were prepared in the same manner as in Example 2-1, except that the combination of the ester and the tertiary alkylamine The long chain alkylamine was modified in the manner shown in Table 11. The long chain tertiary alkylamine was employed in an equimolar amount and in a two-fold molar amount relative to a monofunctional perfluoropolyether and a perfluoropolyether having functional groups. at both ends, respectively. In other words, the long chain tertiary alkylamine was employed in an equimolar amount for one

carboxyl group.

  The resulting sample strips 2-2 to 2-16 were examined for the same characteristics as in Example 2-1. The results

  are also shown in Table 12 above.

  It can be seen from Table 12 that with sample strips 2-2 to 2-16, it is possible to prevent the coefficient of friction from increasing after the operation of the strip and that no vibration of strip appeared during operation in a VCR, and furthermore that it was possible

  to obtain good performance, as in Example 2-1.

  Comparative Examples 2-1 to 2-6 Comparative bands 2-1 to 2-6 were prepared using, in place of the combination of the ester and the long-chain tertiary alkyl amine, only the ester of the perfluoropolyether and the partially fluorinated long-chain carboxylic acid of the lubricant 2-1 employed in Example 2-1 (example

  Comparative 2-1), only the long chain tertiary alkylamine of the lubricant 2-

  1 (Comparative Example 2-2), the ester of Example 2-1 mixed with an equimolar amount of oleylamine as primary amine (Comparative Example 2-3), the ester of lubricant 2-7 of Example 2-7 mixed with an equimolar amount of oleylamine as the primary amine (Comparative Example 2-4), the ester of the 2-11 lubricant of Example 2-11 mixed with an amount of two-fold molar ratio of oleylamine as the primary amine (Comparative Example 2-5) and

  not using lubricant (Comparative Example 2-6).

  Comparative bands 2-2 to 2-6 were examined for the same characteristics as in Example 2-1. The results are shown in Table 13 below.

TABLE 13

  Ex. Comp. Coefficient of friction Coefficient of friction Number of tests of occurrence of n * before operation after operation operation vibrations of the strip 2-1 0.26 0.30 85 no 2-2 0.14 - _ 2 no 2-3 0, 19 0.39> 100 yes 2-4 0.17 0.39> 100 yes yes 2-5 0, 18 0.38> 100 yes 2- 6 0.90 _ 1 yes It can be seen from Table 13 that if the lubricant is simply the long chain tertiary alkyl ester or alkylamine, or if there is no lubricant in the magnetic recording medium, good performance can not be achieved, and if the long-chain primary alkylamine is added to the lubricant, the magnetic recording medium has an increased coefficient of friction after operation and vibrations

  during operation in a VCR.

  Using the sample strips of the present examples, the relationship between the amount of tertiary alkylamine long chain added to the ester and the

  coefficient of friction was examined.

  In other words, lubricant samples were prepared by varying the amount of long chain tertiary alkylamine relative to the ester in a range of 0.01 to 100 in terms of molar ratio and bands.

  Samples were prepared using these lubricant samples.

  The coefficient of friction of the samples produced was measured in the same manner as in Example 2-1. The results are presented in the

Table 14 below.

TABLE 14

  Coefficient of friction Coefficient of friction Molar ratio of amine before operation after operation

0.23 0.27

0.23 0.26

0.20 0.25

1 0.19 0.23

0.5 0.19 0.23

0.01 0.21 0.25

0 0.26 0.30

  The 2-10 lubricant employed in Example 2-10 was prepared in the same manner. Using this lubricant, a sample strip was prepared and its coefficient of friction was checked before and after operation. The

  The results are shown in Table 15 below.

TABLE 15

  Coefficient of friction Coefficient of friction Molar ratio of amine before operation after operation

0.22 0.28

0.21 0.26

0.19 0.24

2 0.18 0.22

1.0 0.18 0.24

0.01 0.20 0.27

0 0.25 0.32

  It can be seen from Tables 14 and 15 that by employing a lubricant prepared by mixing the ester with the long chain tertiary alkylamine in a molar ratio of 0.01 to 100, it is possible to prevent the

  friction after operation to increase.

  Examples 2-17 to 2-32 Sample strips 2-17 to 2-32 were prepared in the same manner as in Example 2-1, except that the combination of ester and tertiary alkylamine long chain lubricant 2-1 used in Example 2-1 was replaced by the combination of the ester represented by the formula (14): RfCH2COOR2 or R2-OCOCH2RfCH2COOR2 (14) where Rf and R2 respectively denote a group perfluoropolyether and a partially fluorinated long-chain hydrocarbon group with the tertiary alkylamine

  long chain shown in the following Table 16.

TABLE 16

Rf Rn Rf 2-17 F (CF2CF2CF2O) nCF2CF2 3,500 C8F25C1OH20 C18H37 CH3 CH3 2-18 F (CF2CF2CF2O) nCF2CF, 3,500 C7F15C16H32 iso-C18H33 CH3 CH3 2-19 F (CF2CF2CF2O) nCF2CF2 C3F7CH = CHC8H16 C18H37 CH3 CH3 2-20 F (CF2CF2CF2O) nCF2CF2 3500 (CF3) 2CFC6F12C16H32 C16H33 CH3 CH3 2-21 F (CF2CF2CF2O) nCF2CF2 3500 C8F17ClOH20 C18H37 CH3 C2H5 2-22 CF3 (OCF (CF3) CF2) m ( OCF2) 1 650 C8F17C1oH20 C18H37 CH3 CH3 2-23 CF3 (OCF (CF3) CF2) min (OCF2) 1650 C3F7CH = CHC8H16 C18H37 CH3 CH3 2-24 CF3 (OCF (CF3) CF2) min (OCF2) 650 C7F15Cl2H2 CH2 ## STR1 ## ) (OCF2) QOCF2 2,000 C7F15C10H2O C16H33 CH3 CH3 2-28 CF2 (OC2F4) p (OCF2) QOCF2 2,000 C12H25C10H2O C14H29 CH3 C2H5 2-29 CF2 (OC2F4) p (OCF2) qOCF2 2,000 C2F5C1H2O C10H21 CH3 CH3 TABLE 16 (continued) N Rf Molecular Weight R1 Ra Rb Rc 2-30 CF2 (OC2F4) p (OCF2) goCF2 2,000 C7F15C16H32 C18H37 CH3 C2H5 2-31 CF2 (OC2F4) p (OCF2) gOCF2 The amount of alkylamine used was adjusted so that it is respectively an equimolar amount and an amount of alkylamine. a two-fold molar amount relative to the monofunctional perfluoropolyether and the perfluoropolyether having functional groups at both ends thereof, i.e., an equimolar amount for a carboxyl group. The resulting sample strips 2-17 to 2-32 were examined for the same characteristics as in Example 2-1. The results

  are shown in Table 17 below.

TABLE 17

  Ex. Comp. Coefficient of friction Coefficient of friction Number of tests of occurrence of n * before operation after operation operation vibrations of the belt 2-17 0.18 0.23> 100 no 2- 18 0.18 0.26> 100 no 2- 19 0.18 0.25> 100 no 2-20 0.21 0.26> 100 no 2-21 0.18 0.24> 100 no 2-22 0 (, 19 0.25> 100 no 2-23 0.20 0.25> 100 no 2-24 0.20 0.26> 100 no 2-25 0.19 0.25> 100 no 2-26 0, 17 0.23> 100 no 2-27 0, 17 0.24> 100 no 2-28 0.20 0.26> 100 no 2-29 0.20 0, 25> 100 no 2-30 0.19 0.24> 100 no 2-31 0.20 0 , 24> 100 no 2-32 0.20 0.25> 100 no It can thus be seen that it was possible to prevent the coefficient of friction after operation from increasing and that no vibrations of the band appeared. during operation in a VCR, so that one has

  achieved satisfactory operating performance.

  Comparative Examples 2-7 to 2-10 Comparative bands 2-7 to 2-10 were prepared using, instead of the combination of the ester and the long-chain tertiary alkyl amine, only the perfluoropolyether ester. with the partially fluorinated long-chain carboxylic acid of the lubricant 2-1 used in Example 2-1 (Comparative Example 2-7), the ester of Example 2-17 mixed with an equimolar amount of oleylamine as the primary amine (Comparative Example 2-8), the ester of the lubricant 2-22 of Example 2-22 mixed with an equimolar amount of oleylamine as the primary amine (Comparative Example 2-9 ), and the ester of the lubricant 2-26 of Example 2-26 mixed with a quantity of two

  molar ratio of oleylamine as the primary amine (Comparative Example 2-10).

  Comparative bands 2-7 to 2-10 were examined for the same characteristics as in Example 2-1. The results are

  presented in Table 18 below.

TABLE 18

  Ex. Comp. Coefficient of friction Coefficient of friction Number of tests of occurrence before operation after operation vibration of the strip 2-7 0.25 0.33 75 no 2-8 0.19 0.39> 100 yes 2-9 0 (, 19 0.37> 100 yes 2-10 0.18 0.39> 100 yes It can be seen from Table 18 that satisfactory operating performance is not obtained with the lubricant consisting solely of a ester and that, with the lubricant containing the long-chain primary alkylamine, the band exhibited an increased coefficient of friction after operation and was subjected to vibrations during operation in a VCR Examples 2-33 to 2-52 Lubricant Samples 2-33 to 2-36 and 2-37 to 2-42 were prepared using as ester the ester of lubricants 2-1 to 2-10, of general formula (13), and adding tertiary alkylamine to long chain, a phosphorus-based extreme pressure agent and a long-chain carboxylic ester

  as shown in Tables 19 and 20 below.

TABLE 19

  Lubricant Extreme Pressure Agent Ester carboxylic to Ra Rb Rc based on long chain phosphor

  2-33 C18H37 CH3CH3 (C12H25) 2POOH C17H35COC 2H5

  2-34 C18H37 CH3 C2H (C16H330) 3P C17H35COOC2H5

  2-35 iso-C18H37 CH3 CH3 (C12H25S) 3P C17H29COOC2H5 2-36 CH2 = CHC16H32 CH3 CH3 (iso-C18H370) 3P C17H35COOC4H9

TABLE 20

  Lubricant Extreme Pressure Agent Ester carboxylic to Ra Rb Rc based on long chain phosphor

  2-37 C18H37 CH CH3 (C12H2O) 2POOH C17H35COOC2H5

  2-38 C16H33 CH3 C2H5 (C12H2O) 3P C17H35COOC2H5

  2-39 C14H29 CH3 CHI (C12H25S) 3P C17H29COOC2H5

  2-40 C18H37 CH! CH! (C18H310) 3P C17H29COOC4H9

  2-41 iso-C18H37 CH3 CH3 (C18H31S) 3P C17H35COOC2H5 2-42 CH2 = CHC16H32 CH3 CH3 (iso-C18H370) 3P C17H35COOC4H9 In addition, lubricant samples 2-43 to 2-46 and 2-47 to 2-52 were prepared using as ester the ester of lubricants 2-17 to 2- 26, of general formula (14), and adding a tertiary alkylamine long chain, a phosphorus-based extreme pressure agent and a carboxylic ester long

  as shown in Tables 21 and 22 below.

TABLE 21

  Lubricant Extreme pressure agent Ester carboxylic acid to Ra Rb Rc based on long chain phosphorus

  2-43 C18H37 CH3 CH3 (C12H25) 2POH C17H35COC2H5

  2-44 C18H37 C2H = H (C18H330) 3P C17H29COOC4H9

  245 iso-C18H37 CH3 CH3 (C12H25S) 3P C17H35COOC2H5 2- 46 CH2 = CHC16H32 CH3 CH3 (iso-C18H370) 3P C17H29COOC2H5

TABLE 22

  Lubricant Extreme pressure agent Ester carboxylic i ne Ra Rb Rc based phosphorus long chain

  2-47 C18H37C CHCH3 (C12H2OO) 3P C17H35COOC2H5

  2-48 C16H33 CH3 C2H5 (C12H2O) 2POH C17H35COOC3H5

  2-49 C14H29 CH3 CH3 (C12H25S) 3P C17H29COOC4H8

  2-50 C18H37 CH3 CH3 (C18H3O) 3P C17H29COC4H9

  2-51 iso-C18H37 CH3 CH3 (C18H31S) 3P C17H35CO (C2H5 2-52 CH2 = CHC16H32 CH3 CH3 (iso-C18H370) 3P C17H35OOC4H Then, using these lubricant samples 2-33 to 2-52, prepared sample strips 2-33 to 2-52 in the same way as in

Example 2-1.

  The resulting sample strips 2-33 to 2-52 were examined for the same characteristics as in Example 2-1. These tapes were used in a VCR not only in a standard environment, but also under 40 C temperature and humidity conditions.

%, and temperature of -5C.

  The results are presented in the following Tables 23 to 26

form examples 2-33 to 2-52.

TABLE 23

  Coefficient of Coefficient of Number of Tests of Number of Tests Number of Tests of Ex. Friction Before Friction After Operation Functioning Operation Occurrence of n Functioning Operation (Standard Environment) (40C, 80%) (-5 C) Vibrations of band 2-33 0.19 0.25> 100> 100> 100 no 2-34 0.18 0.25> 100> 100> 100 no 2-35 (, 19 0.25> 100> 100> 100 no 2-36 0.20 0.26> 100> 100> 100 no

TABLE 24

  Coefficient of Coefficient of Number of Tests of Number of Tests Number of Tests of Ex. Friction Before Friction After Operation Functioning Operation Occurrence of n Functioning Operation (Standard Environment) (40C, 80%) (-5 C) Vibrations of band 2-37 0.18 0.24> 100> 100> 100 no 2-38 0.17 0.25> 100> 100> 100 no 2-39 0.17 0, 24> 100> 100> 100 no 2-40 0.18 0.25> 100> 100> 100 no 2-41 0.18 0.25> 100> 100> 100 no 2-42 0.20 0.25> 100> 100> 100 no

TABLE 25

  Ex. Coefficient of Coefficient of Number of Tests of Number of Trials of Number of Trials of Comp. Friction Before Friction After Operation Functioning Operation Occurrence of Operation (Standard Environment) (40 C, 80%) (-5, C) Band Vibration 2-43 0.19 0.26> 100> 100> 100 yes 2 -44 0.19 0.25> 100> 100> 100 yes 2-45 0.20 0, 26> 100> 100> 100 yes 2-46 0.20 0.25> 100> 100> 100 yes

TABLE 26

  Coefficient of Coefficient of Number of Tests Number of Tests Number of Tests of Ex. Friction Before Friction After Operation Functioning Operation Occurrence of Operation N (Standard Environment) (40C, 80%) (-5'C) Vibrations band 2-47 0.17 0.25> 100> 100> 100 no 2-48 0.17 0.26> 100> 100> 100 no 2-49 0.18 0, 24> 100> 100> 100 no 2-50 0.18 0.26> 100> 100> 100 no 2-51 0.19 0.26> 100> 100> 100 no 2-52 0.20 0.26> 100> 100> 100 no On see from Tables 23 to 26 that with Examples 2-33 to 2-52, it is possible to prevent the coefficient of friction from increasing after operation and to obtain a satisfactory operation in the different

  environments tested, without the appearance of vibrations of the band.

  Comparative Examples 2-11 to 2-14 In lubricants 2-33, 2-37, 2-43 and 2-47 employed in Examples 2-33, 2-37, 2-43 and 2-47, oleylamine has been added as the primary amine in place of the long chain tertiary alkyl amine to prepare lubricants. Using these lubricants, comparative bands 2-11 to 2-14 were

  were prepared in the same way as in Example 2-1.

  These comparative bands were examined for the same characteristics as in Examples 2-33 to 2-52. The results are presented as Comparative Examples 2-11 to 2-14 in Table 27

following.

TABLE 27

  Ex. Coefficient of Coefficient of Number of Tests of Number of Trials of Number of Trials of Comp. friction before operation after operation operation operation n operation operation (standard environment) (40C, 80%) (-5C) vibration of the belt 2-11 0.19 0.40> 100> 100> 100 yes 2-12 0 , 18 0.38> 100> 100> 100 yes 2-13 0.19 0, 40> 100> 100> 100 yes 2-14 0.18 0.39> 100> 100> 100 yes We can see from the above results when using a lubricant obtained by adding a long chain tertiary alkyl amine in a mole ratio range of 0.01 to 100 to a perfluoroether ester having terminal carboxyl groups and alcohol to long chain or partially fluorinated long-chain alcohol, and optionally additionally adding a phosphoric ester, a phosphorous ester, a long chain carboxylic ester or an agent for extreme pressure, it becomes possible to prevent the occurrence of the band and prevent the coefficient of friction from increasing after operation relative to the case where an ester or an amine is used alone or if a primary amine is used in place of the tertiary alkylamine long chain, while it becomes possible to improve the performance of

  operating under different conditions of use.

Example 3-1

  First, a chloride of a long chain carboxylic acid was added dropwise with stirring to a solution of a tertiary amine and a

  perfluoropolyether having terminal hydroxyl groups.

  After the dropwise addition was complete, the reaction was conducted at

term by reflux heating.

  After cooling the resulting product to room temperature, the formed amine salt was washed with distilled water and purified by silica gel chromatography to obtain an ester represented by the following formula (15): RfCH2OCOR1 or R1COOCH2-RfCH2OCOR1 (15) where Rf denotes a perfluoropolyether group and R1 denotes a hydrocarbon group

long chain.

  The ester thus prepared was mixed with a tertiary alkylamine at

  long chain to produce a 3-1 lubricant presented in Table 28 below.

  below. Long-chain tertiary alkylamine was added in an amount

  equimolar with perfluoropolyether.

TABLE 28

  Rf Molecular Weight R1 Ra Rb Rc 3-1 F (CF2CF2CF2O) nCF2CF2, 3500 C1 H23 C12H25 CH3 CH3 3-2 F (CF2CFCF2CF2O) nCF2CF2 3500 C13H27 C14H29 CH3 CH3 3-3 F (CF2-CF2CF2O) nCF2CF2- 3 500 C17H35 C18H37 CH3 CH3 3-4 F (CF2CF2CF2O) nCF2CF2 3500 C6F11 (cyclohexyl) C10H21 CH3 CH3 3-5 F (CF2CF2CF2O) nCF2CF2 3500 C23H47 C12H25 CH3 C2H5 3-6 CF3 (OCF (CF3) CF2) m (OCF2 ) 1 650 C17H35 C18H37 CH3 CH3 3-7 CF3 (OCF (CF3) CF2) m (OCF2) 1650 C13H27 C14H29 CH3 CH3 3-8CF3 (OCF (CF3) CF2) m (OCF2) 1650 CH2 = CHC15H30 C18H37 CH3 CH3 3-9 CF3 (OCF (CF3) CF2) m (OCF2) 1-650 iso-C17H35 CH3 = CHC16H32 CH3 CH3 3-10 CF2 (OC2F4) p (OCF2) qOCF2 2,000 C12H25 C18H37 CH3 CH3 3-11 CF2 (OC2F4) ) (OCF2) QOCF2 2,000 C14H29 C14H29 CH3 CH3 3-12 CF2 (OC2F4) p (OCF2) QOCF2 2,000 C14H29 C14H29 CH3 C2H5 3-13 CF2 (OC2F4) p (OCF2) qOCF2 2,000 C16H33 C16H33 CH3 CH3 TABLE 28 (contd.) Rf Molecular Weight R1 Ra Rb Rc 3-14 CF2 (OC2F4) p (OCF2) gOCF2 2,000 C18H37 L83 CH3 CH3 3-15 CF2 (OC2F4) p (OCF2) gOCF2 2,000 iso-C18H37 C18H37 CH3 CH3 -16 CF2 (OC2F4) p (OCF2) gOCF2 4000 C18H37 C18H37 CH3 CH3 O

  This lubricant 3-1 was applied to the surface of a magnetic layer

  a magnetic magnetic thin film type magnetic recording medium prepared in the usual manner to obtain a 3-1 sample strip. More specifically, a thin magnetic metal film consisting of% Co and 20% Ni was formed by oblique vapor deposition on a

  polyethylene terephthalate film 10 μm thick in the form of a magnetic layer

  tick in a film thickness of 200 nm. The lubricant 3-1 above, dissolved in n-hexane, was applied to the surface of the magnetic layer in one

  amount of 5 mg / m2 to obtain a 3-1 sample strip.

  Then, the coefficient of friction was measured before and after

  in a standard environment. The sample tape was used times in a commercial VCR manufactured by SONY CORPORATION under the trademark EV-S900, at each for 10 min, to determine the number of test runs until the size

  the output is reduced by 3 dB until the vibrations of the band

  The results are shown in Table 29 below.

TABLE 29

  Ex. N 'Coefficient of friction Coefficient of friction Number of tests Occurrence of pre-operation vibration after operation operating band 3-1 0.18 0 (), 23> 100) no 3-2 0.18 0.24 > 100 no 3-3 0.17 0.21> 100 no 3-4 0.20 0.23> 100 no 3-5 0, 19 0.23> 100) no 3-6 0.17 0.22> 100 no 3-7 0.18 0.22> 100 no 3-8 0.19 0.23> 100 no 3-9 0.20 0.24> 100 no 3-10 0.17 0.22> 100 no 3-11 0.17 0.21> 100 no 3-12 0.19 0.23> 100 no 3-13 0.18 0.21> 100 no 3-14 0, 17 0.20> 100 no 3- 0.20 0.24> 100 no 3-16 0.19 0.23> 100 no It can be seen from Table 29 that by applying lubricant 3-1 to the surface of the magnetic layer it is possible to to prevent the coefficient of friction from increasing after operation and to prevent vibrations of the band during operation in a video recorder, thereby ensuring satisfactory operating performance. Examples 3-2 to 3-16 Sample strips 3-2 to 3-16 were prepared in the same manner as sample strip 3-1 except that the combination of tertiary alkylamine and ester was long. chain was replaced by that shown in Table 28. The alkylamine was used in an equimolar and a two-fold molar amount, respectively, relative to the functional perfluoropolyether and

  perfluoropolyether having functional groups at both ends, that is,

  that is, an equimolar amount for a hydroxyl group.

  The resulting sample strips 3-2 to 3-16 were examined for the same characteristics as in Example 3-1. The results

  are also shown in Table 29.

  It can thus be seen that, as in Example 3-1, the coefficient of friction does not increase after operation and that there is no vibration of the band during operation in a video recorder, which

  guarantees satisfactory operating performance.

  Comparative Examples 3-1 to 3-6 Comparative bands 3-1 to 3-6 were prepared employing, in place of the combination of the ester and the long-chain tertiary alkyl amine, only the perfluoropolyether and long chain carboxylic acid

  lubricant 3-1 used in Example 3-1 (Comparative Example 3-1), only

  long-chain tertiary alkylamine of lubricant 3-1 (comparative example

  3-2), the ester of Example 3-1 mixed with an equimolar amount of oleyl-

  amine as the primary amine (Comparative Example 3-3), the ester of the 3-7 lubricant of Example 3-7 mixed with an equimolar amount of oleylamine as the primary amine (Comparative Example 3- 4), the ester of the lubricant 3-11 of Example 3-11 mixed with a two-fold molar amount of oleylamine as the primary amine (Comparative Example 3-5) and not employing

  lubricant (Comparative Example 3-6).

  Comparative bands 3-1 to 3-6 were examined for the same characteristics as in Example 3-1. The results are

  presented in Table 30 below.

TABLE 30

  Ex. Comp. Coefficient of friction Coefficient of friction Number of tests of occurrence of vibration of the ne before operation after operation operation band 3-1 0.24 0.30 85 no 3-2 0, 14 - 2 yes 3-3 0.17 0 , 39> 100 yes yes 3-4 0,17 0,38> 100 yes 3-5 0,17 0,36> 100 yes yes 3-6 0,17 _> 100 yes yes We can see from table 3 that if only the ester or only the tertiary alkylamine is used as a lubricant, or even if no lubricant is used, it is not possible to obtain good performance of operation, and if the the long chain primary alkylamine is added to the lubricant, the coefficient of friction after operation increases, while vibrations of the band occur during operation of the tape in a VCR. Then, using the sample strips of this example, the relationship

  between the amount of tertiary alkylamine added to the ester and the coefficient of friction between

was examined.

  In other words, lubricants were prepared in which the amount of long chain tertiary alkylamine relative to the ester was varied and was in a range of 0.01 to 100 in terms of molar ratio, and we have

  prepared sample strips using these lubricants.

  The coefficient of friction of each sample band was measured in the same manner as in Example 3-1. The results are presented in the

Table 31 below.

TABLE 31

  Coefficient of friction Coefficient of friction Molar ratio of amine before operation after operation

0.22 0.26

0.22 0.25

0.20 0.24

1 0.18 0.23

0.5 0.19 0.23

0.01 0.20 0.25

0 0.24 0.30

  On the other hand, the 3-10 lubricant employed in Example 3-10 was prepared in the same manner as above and sample strips were prepared using the resulting lubricant to examine the coefficient of friction of the lubricants. sample strips before and after operation. The obtained results

  are shown in Table 32 below.

TABLE 32

  Coefficient of friction Coefficient of friction Molar ratio of amine before operation after operation

0.20 0.26

0.20 0.24

0.19 0.23

2 0.17 0.22

1.0 0.17 0.24

0.01 0.19 0.26

0 0.24 0.32

  It can be seen from Tables 31 and 32 that when a lubricant obtained by adding the long-chain tertiary alkylamine to the ester in a range of 0.01 to 100, the coefficient can be prevented. of

  friction after operation to increase.

  It can be seen from the above results that when a lubricant obtained by adding a long-chain tertiary alkylamine to an ester of a perfluoropolyether having a terminal hydroxyl group in an amount of

  0.01 to 100 in terms of molar ratio and additionally adding a phosphoric ester

  a phosphorous ester, an ester of a long-chain carboxylic acid or an agent for extreme pressure at the resulting mixture, the coefficient of friction after operation and the vibrations of the band increase to a lesser extent than in the case where only the ester or amine is used or in the case where a primary amine is used in place of the long chain tertiary alkyl amine, while the operating performance of the strip is also

  improved in different operating conditions.

Claims (12)

  1. Lubricant characterized in that it comprises an ester of a perfluoro-   polyether having a terminal hydroxyl group, and a partially fluorinated long-chain carboxylic acid represented by the formula (1): RfCH2OCOR1 or R1COOCH2-RfCH2-OCOR1 (1) where Rf is a perfluoropolyether group and R1 is a hydrocarbon group having long chain partially fluorinated, and a tertiary alkylamine long chain represented by the formula (2) Rb Ra-N-Rc (2) in mixture with said ester, o Ra, Rb and Rc are hydrocarbon groups of which at least one denotes a long-chain hydrocarbon group having 3 carbon atoms carbon or more.   2. Lubricant according to claim 1, characterized in that it further comprises at least one ester from a phosphoric ester, a phosphorous ester and a   long chain carboxylic acid ester.   3. Lubricant according to claim 1, characterized in that the amount of tertiary alkylamine long chain represented by the formula (2) is in the range of molar ratio of 0.01 to 100 relative to the amount of 'ester represented by formula (1).   A magnetic recording medium having a thin magnetic metal film formed on a non-magnetic substrate, characterized in that a lubricant according to claim 1 is present on the surface of said thin film magnetic metal.   5. Lubricant characterized in that it comprises an ester of a perfluoro-   polyether having a terminal carboxyl group and a long-chain alcohol represented by the formula (3): RfCH2COOR1 or R10COCH2RfCH2COOR1 (3) where Rf is a perfluoropolyether group and R1 is a long-chain hydrocarbon group, and a tertiary alkylamine is long chain represented by the formula (4): Rb Ra-N-Rc (4) mixed with said ester, o Ra, Rb and Rc are hydrocarbon groups, at least one of which denotes a long-chain hydrocarbon group having 3 atoms of carbon or more.   6. Lubricant characterized in that it comprises an ester of a perfluoro-   polyether having a terminal carboxyl group, and a partially fluorinated long-chain alcohol represented by the formula (5): RfCH2COOR2-   or R2OCOCH2RfCH2-COOR2 (5) wherein Rf is a perfluoropolyether group and R2 is a partially fluorinated long-chain hydrocarbon group, and a long-chain tertiary alkylamine represented by the formula (6): Rb Ra-N-Rc (6) mixture with said ester, o Ra, Rb and Rc are hydrocarbon groups of which at least one denotes a long-chain hydrocarbon group having 3 carbon atoms. carbon or more.   7. Lubricant according to claim 5, characterized in that it further comprises at least one ester selected from a phosphoric ester, a phosphorous ester   and a long chain carboxylic acid ester.   8. Lubricant according to claim 5, characterized in that the amount of tertiary alkylamine long chain represented by the formula (4) is in a range of molar ratio of 0.01 to 100 relative to the amount of 'ether represented by the formula (3).   A magnetic recording medium comprising a thin magnetic metal film formed on a non-magnetic substrate, characterized in that a lubricant according to claim 5 is present on the surface of said thin film magnetic metal.   10. Lubricant characterized in that it comprises an ester of a perfluoro-   polyether having a terminal hydroxyl group and a long-chain carboxylic acid represented by the formula (7): RfCH2OCOR1 or R1lCOOCH2RfCH2-OCOR1 (7) where Rf is a perfluoropolyether group and R1 is a long chain hydrocarbon group, and a long chain tertiary alkylamine represented by the formula (8): Rb I Ra-N-Rc (8) mixed with said ester, o Ra, Rb and Rc are hydrocarbon groups of which at least one denotes a hydrocarbon group with long chain having 3 atoms carbon or more.   11. Lubricant according to claim 10, characterized in that the amount of tertiary alkylamine long chain represented by the formula (8) is in a range of molar ratio of 0.01 to 100 relative to the amount of   the ester represented by formula (7).   A magnetic recording medium comprising a thin magnetic metal film formed on a non-magnetic substrate, characterized in that a lubricant according to claim 10 is present on the surface of said thin magnetic metal film.