This inventions relates to lubricating compositions endowed with high antiwear properties comprising: PA0 A) from 100 to 0.1%, but preferably from 10 to 0.5% by weight of a polyether of general formula: ##STR1## where: T, T' either the same or different from each other are inert end groups --CF.sub.2 X, --C.sub.2 F.sub.4 X, --C.sub.3 F.sub.6 X or fluorinated reactive end groups containing carboxylic and/or alcoholic and/or ketonic and/or amidic and/or aminic and/or alkoxylic, at least one of T and T' being one of said reactive end groups; PA1 X=F, Cl; PA1 m, n, s, p=integers such that the polyether has an average molecular wieght ranging from 1,000 to 100,000, on conditions that, when none of them is zero, s/p is about 10, s/n ranges from 0.5 to 1.5, n/m is about 10, while when n is zero, s/n is about 10 and s/m is about 20, while when s, p are zero, n/m ranges from 0.6 to 2; PA0 B) from 0 to 99.9%, but preferably from 90 to 99.5% by weight of a perfluoropolyether having non-reactive end groups. The lubricating compositions, object of the present invention, can be used, with the aid of proper thickening agents, also for the formulation of lubricating greases having high antiwear properties.

FIELD OF THE INVENTION 
The present invention relates to compositions based on perfluoropolyether 
compounds, endowed with lubricating characteristics and improved antiwear 
properties. 
BACKGROUND OF THE INVENTION 
From Italian patent application No. 20,322 A/86 it is known the use of 
fluid perfluoropolyethers endowed with a kinematic viscosity ranging from 
8,000 to 40,000 cSt at 20.degree. C.--as lubricating oils or components of 
perfluorinated lubricating greases in order to obtain lubricants having a 
low friction coefficient. 
In said patent application it is proved that it is not possible to obtain a 
low friction coefficient from perfluoropolyethers of the straight type 
endowed with a low kinematic viscosity, for example of 30-250 cSt. 
On the other hand it is found that the antiwear properties of a 
perfluoropolyether cannot be directly correlated to the friction 
coefficient, as such properties do not improve as the viscosity increases. 
Furthermore, from Italian patent application No. 20,159 A/86 there are 
known several additives for lubricants based on perfluoropolyether 
compounds, which impart antirust properties to said perfluoropolyethers. 
Also in such case these additives seem not to impart particular antiwear 
properties to the perfluoropolyether lubricants, thereby proving that such 
properties cannot be directly correlated to the antirust properties. 
On the other hand, the antiwear characteristics of the perfluoropolyether 
lubricants are similar to the ones of the mineral oils and not fully 
satisfactory for most of the practical applications of the lubricants. 
SUMMARY OF THE INVENTION 
The applicant has now found that lubricants consisting of fluoropolyethers 
having general formula: 
##STR2## 
or compositions based on perfluoropolyethers as defined hereinafter, 
containing the fluoropolyethers of formula (I) as additives, exhibit 
better antiwear properties.

DETAILED DESCRIPTION OF THE INVENTION 
In formula (I), the perfluorooxyalkylene units having indexes m, n, s, p 
are randomly distributed along the chain. 
The coefficients m, n, s, p in the structure of formula (I) are integers 
such that the products comprised in said structure exhibit an average 
molecular weight in the range from 1,000 to 100,000, but preferably from 
2,000 to 5,000. When none of such coefficients is zero, the s/p ratio is 
of about 10, the s/n ratio ranges from 0.5 to 1.5 and the n/m ratio is of 
about 10. When n is equal to zero, s/p is about 10, while s/m is about 20; 
when s, p are equal to zero, n/m ranges from 0.6 to 2. 
Perfluorooxyalkylene units of formula (--CF.sub.2 --CF.sub.2 --CF.sub.2 O) 
and/or (--CF.sub.2 CF.sub.2 CF.sub.2 CF.sub.2 O--) can also be present in 
the structure of formula (I). 
End groups T and T', either the same or different from each other, are 
comprised in the group of inert end groups of formula CF.sub.2 X--, 
C.sub.2 F.sub.4 X--, C.sub.3 F.sub.6 X-- and in the group of fluorinated 
reactive end groups containing carboxylic, alcoholic, amidic, ketonic, 
aminic, alkoxylic, among which, for example, are cited the ones of 
formula: 
##STR3## 
wherein: X=F, Cl; 
R.sub.1, R.sub.2 the same or different from each other, are H or alkyl, 
alkylaryl, aryl radicals, optionally containing substituents such as, for 
example, --OH, halogens, or they can form with N a heterocyclic radical, 
which can contain also other heteroatoms such as O, S, P; 
A means a primary, secondary or tertiary amine or a heterocyclic base, 
optionally containing also other heteroatoms such as O, S, P; 
Y=--OCH.sub.3, --NH.sub.2, --NR.sub.1 R.sub.2 ; 
on condition that at least one out of T and T' is one of the abovesaid 
reactive groups; or, when coefficients s, p are zero, T and T', the same 
or different from each other, are groups --CF.sub.2 --CH.sub.2 OH, 
--CF.sub.2 --COOH, --CF.sub.2 --CN. 
The products of structure (I) are obtainable from the precursors of general 
formula: 
##STR4## 
where m, n, s, p, X have the same value as defined hereinbefore, while L 
and L', the same or different from each other, are comprised in the group 
of inert end groups of formula --CXF.sub.2, --C.sub.2 XF.sub.4, --C.sub.3 
XF.sub.6 where X=F, Cl and in the group of reactive end groups of formula: 
##STR5## 
at least L or L' being one of such reactive end groups. 
In the structure of formula (II), also groups (--CF.sub.2 CF.sub.2 CF.sub.2 
O--) and/or (--CF.sub.2 CF.sub.2 CF.sub.2 CF.sub.2 O--) can be present. 
The precursors of formula (II) are preparable according to known 
techniques, by reaction of one or more perhaloolefins, such as e.g. 
tetrafluoroethylene, hexafluoropropene, chlorotrifluoroethylene, with 
oxygen in the presence of ultraviolet radiations, at temperatures of from 
-80.degree. to +40.degree. C., in the presence or in the absence of 
solvents, and by subsequent heat-treatment, at 200.degree.-250.degree. C., 
of the products so obtained in order to decompose the peroxide groups 
(--O--O--), if any, present therein. 
In the structure of formula (II), X is F when n has value zero, while when 
s, p are equal to zero, the reactive end groups are constituted by 
--CF.sub.2 COF, and X is F or Cl. 
The products of structure (I) can be obtained from those of structure (II) 
either directly or by reaction of the reactive end groups present in the 
latter with proper reagents, such as H.sub.2 O or amine NHR.sub.1 R.sub.2, 
or by further conversion of the resulting groups to yield alcoholic 
groups, by reduction of the corresponding carboxylic groups, nitrile 
groups, by dehydration of the corresponding primary amidic groups, and 
quaternary ammonium carboxylated groups by treatment of the carboxylic 
groups with amines. 
The above-mentioned compounds of formula (I) can be used, besides as such, 
as additives which promote the antiwear properties in perfluoropolyethers 
belonging to one of the following classes: 
##STR6## 
where X is --F, --CF.sub.3 ; A and A', the same or different from each 
other, can be --CF.sub.3, --C.sub.2 F.sub.5, --C.sub.3 F.sub.7. Units 
(CF.sub.2 CF(CF.sub.3)O) and (CFXO) are randomly distributed along the 
perfluoropolyether chain, m and n are integers such that the m/n ratio 
ranges from 20 to 1,000 and the perfluoropolyether viscosity ranges from 
10 to 4,000 cst. 
These perfluoropolyethers are obtained by photo-oxidation reaction of 
hexafluoropropene according to the process described in British patent 
1,104,482, and by successive conversion of the end groups into inert 
groups according to the process described in British patent 1,226,566. 
##STR7## 
where B can be --C.sub.2 F.sub.5, --C.sub.3 F.sub.7, and m is a positive 
integer such that the product viscosity is in the range of the values 
indicated above for class 1. 
These compounds are prepared by ionic oligomerization of the 
hexafluoropropene epoxide and successive treatment of acyl fluoride (COF) 
with fluorine according to the processes indicated in U.S. Pat. No. 
2,242,218. 
##STR8## 
where m is an integer such that the product viscosity is in the 
above-specified range. 
These products are obtained by ionic telomerization of the 
hexafluoropropene epoxide and successive photochemical dimerization of 
acyl fluoride, according to the processes described in U.S. Pat. No. 
3,214,478. 
EQU 4. A'O[CF.sub.2 CF(CF.sub.3)O].sub.m --(C.sub.2 F.sub.4 O).sub.n 
(CFXO).sub.q A 
where A and A', the same or different from each other, can be --CF.sub.3, 
--C.sub.2 F.sub.5, --C.sub.3 F.sub.7 ; X is --F, --CF.sub.3 ; m, n and q 
are integers and can be also equal to 0, but in any case they are such 
that the perfluoropolyether viscosity is in the range indicated 
hereinabove. 
These products are obtained by photo-oxidation of mixtures of C.sub.3 
F.sub.6 and C.sub.2 F.sub.4 and successive treatment with fluorine 
according to the process described in U.S. Pat. No. 3,665,041. 
EQU 5. CF.sub.3 O(C.sub.2 F.sub.4 O).sub.p (CF.sub.2 O).sub.q --CF.sub.3 
where p and q are integers like or different from each other, with the p/q 
ratio being comprised between 0.1 and 5, and such that the viscosity is in 
the above indicated range. 
These perfluoropolyethers are prepared by photochemical oxidation of 
C.sub.2 F.sub.4 according to U.S. Pat. No. 3,715,378 and subsequent 
treatment of the photo-oxidation product with fluorine according to U.S. 
Pat. No. 3,665,041. 
EQU 6. AO--(CF.sub.2 --CF.sub.2 --CF.sub.2 O).sub.m --A' 
where A and A', the same or different from each other, can be --C.sub.2 
F.sub.5, --C.sub.3 F.sub.7, and m is an integer such that the product 
viscosity is in the range of the above-indicated values. 
These products are obtained according to European patent No. 148,482. 
EQU 7. DO--(CF.sub.2 --CF.sub.2 O).sub.r D' 
where D and D', the same or different from each other, can be --CF.sub.3, 
--C.sub.2 F.sub.5, and r is an integer such that the product viscosity is 
in the abovesaid range of values. These products are prepared according to 
U.S. Pat. No. 4,523,039. 
##STR9## 
where R'.sub.f is a perfluoroalkyl, n is at least 8, R.sub.f is F or a 
perfluoroalkyl. 
These perfluoropolyethers are described in PCT patent application WO 
87/00538. 
Other basic fluids, which can be additioned with the compounds of formula 
(I), can be, besides the ones cited hereinbefore, paraffinic and/or 
aromatic mineral oils, polyolefins, siliconic and fluosiliconic fluids, 
and polyphosphazenes. 
The perfluoropolyethers of classes from 1 to 8 cited hereinbefore have 
perfluoroalkyl inert end groups, are liquid with a very low vapor tension 
and exhibit a viscosity, at 20.degree. C., generally ranging from 50 to 
100,000 cSt, preferably from 100 to 2,000 cSt. The above described 
products of formula (I) are soluble in these fluids. 
Thus, object of the present invention is the use, as antiwear lubricants, 
of compositions comprising from 100 to 0.1%, but preferably from 10 to 
0.5% by weight of a polyether of formula (I) cited above, and from 0 to 
99.9%, but preferably from 90 to 99.5% by weight of a perfluoropolyether 
(basic fluid) belonging at least to one of classes 1 to 8 illustrated 
hereinbefore. 
EXAMPLES 
The following examples are given to illustrate but not to limit the scope 
of the present invention. 
Said examples refer to the characterization of lubricating oils comprising 
perfluoropolyethers of the above cited classes 1 to 8 and/or 
fluoropolyethers of general formula (I). 
The lubricating oils of such examples, consisting of, or containing or not 
containing the perfluoropolyethers of said formula (I), have been 
characterized, as regards their antiwear properties, by means of the four 
ball wear machine, ASTM D 4172B method, under those operative conditions, 
under which a mixed lubrication occurs. 
SUMMARY OF THE UTILIZED MEASUREMENT METHOD 
Three steel balls (0.5 in. diameter) were fixed in a proper container and 
coated with the lubricant to be evaluated. 
A fourth ball of the same type as the preceding ones and placed above them 
in order to have three contact points, was rotated, under a prefixed load, 
for a predetermined time. The lubricant was thermoregulated at a given 
temperature. 
The behaviours of the lubricants were compared on the basis of the average 
wear diameter of the fixed balls. 
APATUS 
The test apparatus comprises an electric motor and a pulley system which 
permits to operate at different speeds of rotation. A spindle, which 
contains the upper test-piece consisting of a steel ball (0.5 in. 
diameter) is integral with the driven shaft. 
In a container, placed in proximity of the rotating ball, there are 
arranged three further balls identical, as to diameter and material, with 
the preceding ball, and fixed and immersed in the lubricant. 
The variable load, applicated from down upward, pushes the underlying balls 
against the ball integral with the spindle. 
The load is applicated by means of a level system. 
An induction heating device keeps constant the lubricant temperature in the 
inside of the container; a thermocouple is arranged therein. 
Once the prefixed lubricant temperature has been reached, the prefixed load 
has been applicated and the shaft speed of rotation has been selected, the 
test is started and carried on for the predetermined time. 
TEST CONDITIONS 
The reported results refer to tests carried out under the following 
conditions: 
load: 40 kg 
temperature: 75.degree. C. 
speed of rotation: 1200 r.p.m. 
time: 60 minutes. 
PREATION OF THE BALLS 
The balls, of the chrome steel type, made of AISI steel Standard No. 
E-52100, having a diameter of 0.5 in., grade 25 EP (Extra Polish), were 
cleaned and degreased by immersion first in n-hexane (15 minutes), then in 
Delifrene HP (trichlorotrifluorethane) (15 minutes), at last dried with 
anhydrous air. 
WEAR EVALUATION 
On conclusion of the test and without removing the three fixed (lower) 
balls from the housing, by means of a microscope having a sensitivity of 
0.01 mm, the wear was measured for each ball; for each ball, after having 
removed the oil from the housing by letting it drop for 15 minutes and 
having washed in particular the wear area with Delifrene HP, two diameters 
of the wear impression produced on the surface in consequence of rotation 
were measured, one diameter in the direction of rotation and the other 
diameter perpendicularly to the former (6 detections); then, the average 
of the values was made, so obtaining the result of the test, which is the 
average wear diameter (mm). 
EXAMPLES 1-5 
Compositions were prepared by using, as basic fluids, perfluoropolyethers 
having different viscosities, belonging to class 1, of formula: 
##STR10## 
where X=CF.sub.3, F 
A; A'=CF.sub.3, C.sub.2 F.sub.5, C.sub.3 F.sub.7 
m/n=20 
and, as additives, fluoropolyethers having different average molecular 
weights, of formula: 
##STR11## 
Such compositions were prepared by mixing the basic fluids with the 
additives. 
The characteristics of each basic fluid and of the additive, their amounts 
in the composition and the value of the average wear diameter relating to 
each composition are reported in table 1. 
TABLE 1 
______________________________________ 
BASIC FLUID ADDITIVE RESULT 
EXAM- Viscosity at 
% by % by average wear 
PLES 20.degree. C. (cSt) 
wg. M.W. wg. diameter (mm) 
______________________________________ 
1 250 95 2400 5 0.50 
2 250 95 2100 5 0.57 
3 250 90 2400 10 0.64 
4 450 97 4150 3 0.60 
5 1200 95 4150 5 0.60 
______________________________________ 
EXAMPLE 6 
The determination of the antiwear properties was carried out only on the 
additive of example 1, not mixed with any basic fluid. 
The average wear diameter was equal to 0.65 mm. 
EXAMPLE 7 
Example 1 was repeated, but using, as an additive, the compound of formula: 
##STR12## 
having an average molecular weight of about 2,400, and in an amount equal 
to 6% by weight referred to the mixture with the basic fluid. 
The average wear diameter was equal to 0.48 mm. 
EXAMPLES 8-9 
There were determined the antiwear properties of compositions consisting of 
the basic fluid of class 1 with an additive of formula: 
##STR13## 
The characteristics of the compositions and the results of the wear tests 
are reported in table 2. 
TABLE 2 
______________________________________ 
ADDITIVE 
BASIC FLUID Average RESULT 
Viscosity at 
% by molecular 
% by Average wear 
EX. 20.degree. C. (cSt) 
wg. wg. wg. dia. (mm) 
______________________________________ 
8 250 95 2,400 5 0.50 
9 450 97 2,400 3 0.56 
______________________________________ 
EXAMPLES 10-12 
There were evaluated the antiwear properties of the perfluoropolyethers of 
class 1, used as basic fluids in examples 3, 4 and 5, without additives. 
The found average wear diameters were 0.85, 0.78 and 0.73 mm, 
respectively. 
EXAMPLES 13-14 
There were determined the antiwear properties of compositions consisting of 
basic fluids of classes 4 and 5, respectively: 
##STR14## 
where: X=F, CF.sub.3 
m/n=1.5; m/q=15 
A, A', the same or different from each other, are --CF.sub.3 and/or 
--C.sub.2 F.sub.5 and/or --C.sub.3 F.sub.7, 
having a kinematic viscosity at 20.degree. C. equal to 250 cSt and an 
average molecular weight of 4,000, and 
EQU CF.sub.3 O(CF.sub.2 CF.sub.2 O).sub.p (CF.sub.2 O).sub.q CF.sub.3 
where: 
p/q=1, 
having a kinematic viscosity at 20.degree. C. equal to 150 cSt and an 
average molecular weight of 7,850, and of 5% by weight of the same 
additive of example 1. 
The wear tests on the two compositions gave values of the average diameter 
equal to 0.53 and 0.70 mm, respectively. 
EXAMPLE 15 
There were determined the antiwear properties of a composition consisting 
for 95% by weight of the perfluoropolyether (basic fluid) of example 14, 
and for 5% by weight of an additive mixture having a kinematic viscosity 
at 20.degree. C. equal to 80 cSt, consisting for 97% by weight of the 
compound of formula: 
EQU HOCH.sub.2 --CF.sub.2 --Rf--CF.sub.2 --CH.sub.2 OH 
and for 3% by weight of the compound of formula: 
EQU HOOC--CF.sub.2 --Rf--CF.sub.2 --COOH 
where: Rf=perfluoropolyethereal chain having an average molecular weight 
equal to 2,000 and structure 
EQU O(--CF.sub.2 CF.sub.2 O).sub.n (CF.sub.2 O).sub.m 
where n/m is equal to 0.7. 
The average wear diameter was equal to 0.64 mm. 
EXAMPLES 16-17 
The antiwear properties of the perfluoropolyethers used as basic fluids in 
examples 13 and 14 (classes 4 and 5, respectively), without addition of 
additives, were evaluated. 
The average wear diameter was equal to 0.90 and 0.92 mm, respectively. 
EXAMPLES 18-19 
Comparison Tests 
In these two examples there were determined the antiwear properties of a 
perfluoropolyether of the type of class 5, having a kinematic viscosity, 
at 20.degree. C., equal to 250 cSt, additioned with 2% by weight of 
fluorinated phosphine of formula: 
##STR15## 
(a conventional stabilizer for perfluoropolyethers), and the antiwear 
characteristics of the same perfluoropolyether, but without additive. 
The first example provided an average wear diameter of 1.52 mm, the second 
example, an average wear diameter of 0.94 mm. 
EXAMPLE 20 
Comparison Test 
A composition was prepared, which comprised 97% by weight of a basic fluid 
consisting of the perfluoropolyether of example 1 and 3% of an additive 
mixture composed for 97% by weight of a compound of formula: 
EQU NC--CF.sub.2 --Rf--CF.sub.2 --CN 
and for 3% by weight of a compound of formula: 
EQU HOOC--CF.sub.2 --Rf--CF.sub.2 --COOH 
where: Rf=perfluoropolyethereal chain having an average molecular weight 
equal to 2,000, having the structure defined in example 15. 
Said additive mixture is described in Italian patent application No. 20,183 
A/88, in the name of the Applicant, as a mixture capable of imparting 
antirust properties to the perfluoropolyether of the present example. 
The resulting average wear diameter was equal to 1.04 mm. 
EXAMPLE 21 
Example 1 was repeated using, as an additive, the compound of formula: 
##STR16## 
where s/p=10, 
s/m=20, 
p/m=2 
T=CF.sub.2 --COOH 
having an average molecular weight of about 5,000 and in an amount equal to 
2% by weight referred to the mixture with the basic fluid. 
The average wear diameter was equal to 0.69 mm. 
EXAMPLE 22 
There were evaluated the antiwear properties of compositions consisting of 
the basic fluid of example 1, using, as an additive, the compound of 
formula: 
##STR17## 
where s/p=10, 
s/m=20, 
p/m=2 
##STR18## 
having an average molecular weight equal to 2,100. 
Compositions containing 2% and 4% by weight of the additive on the mixture 
with the basic fluid were evaluated; the average wear diameter was equal 
to 0.49 mm for both additive concentrations taken into examination. 
EXAMPLE 23 
There were determined the antiwear properties of a grease prepared 
according to Italian patent No. 1,151,732, containing, as a basic fluid, 
the perfluoropolyether of class 1 described in examples 1 to 5, having a 
kinematic viscosity of 1,500 cSt at 20.degree. C. (66.5% by weight), as an 
additive, the additive described in examples 1 to 5, having an average 
molecular weight equal to 2,250 (3.5% by weight) and, as a thickening 
agent, polytetrafluoroethylene (PTFE) such as Algoflon L 206 (produced by 
the Applicant) (30% by weight). 
The average wear diameter was equal to 0.98 mm. 
EXAMPLE 24 
According to the technology cited in example 23, a grease was prepared by 
using, as a basic fluid, only the additive used in example 23 (70% by 
weight) and, as a thickening agent, PTFE type Algoflon L 206 (30% by 
weight). 
On the grease, the antiwear properties and the average wear diameter, which 
was equal to 0.70 mm, were determined. 
EXAMPLE 25 
According to the technology of example 23, a grease containing, as a basic 
fluid, the same perfluoropolyether used in example 23 (67.8%) and, as an 
additive, the same additive (2.2% by weight) described in example 15, was 
prepared. As a thickener for the formulation of the grease, PTFE type 
Algoflon L206 was used. 
From the wear test carried out on the grease so prepared, a value of the 
average diameter equal to 0.96 mm was obtained. 
EXAMPLE 26 
Comparison Test 
There were determined the antiwear properties of a grease prepared as is 
described in example 23, containing, as a basic fluid, the same 
perfluoropolyether of example 23 and, as a thickener, PTFE type Algoflon 
L206. 
The average wear diameter was equal to 1.4 mm. 
Although the invention has been described in conjunction with specific 
embodiments, it is evident that many alternatives and variations will be 
apparent to those skilled in the art in light of the foregoing 
description. Accordingly, the invention is intended to embrace all of the 
alternatives and variations that fall within the spirit and scope of the 
appended claims. The above references are hereby incorporated by reference 
.