U.S. patent application number 11/448670 was filed with the patent office on 2006-12-14 for fluorinated lubricants.
This patent application is currently assigned to SOLVAY SOLEXIS S.p.A.. Invention is credited to Patrizia Maccone, Giuseppe Marchionni.
Application Number | 20060281640 11/448670 |
Document ID | / |
Family ID | 36955987 |
Filed Date | 2006-12-14 |
United States Patent
Application |
20060281640 |
Kind Code |
A1 |
Maccone; Patrizia ; et
al. |
December 14, 2006 |
Fluorinated lubricants
Abstract
Fluorinated lubricants comprising "pour point depressant"
additives of structure:
X.sub.1--O(CF.sub.2O).sub.n(CF.sub.2CF.sub.2O).sub.m(CF.sub.2CF.sub.2CF.s-
ub.2O).sub.p(CF.sub.2CF.sub.2CF.sub.2CF.sub.2O).sub.q--X.sub.2
(I)wherein X.sub.1, X.sub.2, have formula
--(CF.sub.2).sub.zCF.sub.3 wherein z is an integer from 0 to 3; n
is an integer between 1 and 200; m is an integer between 0 and 200;
p, q are integers between 0 and 10; (p+q)/(p+q+m+n).ltoreq.0.05;
m/n.ltoreq.0.7; the number average molecular weight of (I) is
between 1,000 and 10,000.
Inventors: |
Maccone; Patrizia; (Milano,
IT) ; Marchionni; Giuseppe; (Milano, IT) |
Correspondence
Address: |
ARENT FOX PLLC
1050 CONNECTICUT AVENUE, N.W.
SUITE 400
WASHINGTON
DC
20036
US
|
Assignee: |
SOLVAY SOLEXIS S.p.A.
|
Family ID: |
36955987 |
Appl. No.: |
11/448670 |
Filed: |
June 8, 2006 |
Current U.S.
Class: |
508/182 |
Current CPC
Class: |
C10M 2213/04 20130101;
C10N 2030/08 20130101; C10M 2213/043 20130101; C10M 169/041
20130101; C10M 147/04 20130101; C10M 107/38 20130101; C10N 2040/06
20130101; C10N 2020/04 20130101; C10N 2020/02 20130101; C10N
2040/30 20130101 |
Class at
Publication: |
508/182 |
International
Class: |
C10M 169/00 20060101
C10M169/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 10, 2005 |
IT |
MI2005 A 001081 |
Claims
1. Use as "pour point depressant" additives for fluorinated oils,
of compounds having the following structure:
X.sub.1--O(CF.sub.2O).sub.n(CF.sub.2CF.sub.2O).sub.m(CF.sub.2CF.sub.2CF.s-
ub.2O).sub.p(CF.sub.2CF.sub.2CF.sub.2CF.sub.2O).sub.q--X.sub.2 (I)
wherein: the repeating units --CF.sub.2O--, --CF.sub.2CF.sub.2O--,
--CF.sub.2CF.sub.2CF.sub.2O--,
--CF.sub.2CF.sub.2CF.sub.2CF.sub.2O--, are statistically
distributed along the chain; --X.sub.1 and --X.sub.2 are
perfluoroalkyl chain end groups equal to or different from each
other, having formula --(CF.sub.2).sub.zCF.sub.3 wherein z is an
integer from 0 to 3; n is an integer from 1 to 200, m is an integer
from 0 to 200, p, q are integers from 0 to 10, preferably from 0 to
5, more preferably from 0 to 1, still more preferably 0, with the
proviso that: the ratio (p+q)/(p+q+m+n) is lower than or equal to
0.05, being also equal to 0, (p+q+m+n) being different from 0; the
ratio m/n, when n is different from 0, is lower than or equal to
0.7, preferably lower than 0.5, more preferably lower than 0.35;
the number average molecular weight of the compounds (I) ranges
from 1,000 to 10,000, preferably from 2,000 to 8,000, more
preferably from 2,400 to 5,000; the chlorine atoms in the compounds
of formula (I) determined by .sup.19F NMR analysis are
substantially absent.
2. Use according to claim 1, wherein the fluorinated oils are
perfluoropolyether oils having viscosity at 20.degree. C. between
10 and 4,000 cSt, preferably between 30 and 2,000 cSt, and
containing one or more of the following repeating units: --CFXO--
wherein X is equal to F or CF.sub.3; --CF.sub.2CF.sub.2O--,
--(C.sub.3F.sub.6O)--, --CF.sub.2CF.sub.2CF.sub.2O--,
--CF.sub.2CF.sub.2CF.sub.2CF.sub.2O--, said units being
statisticall distributed along the backbone.
3. Use according to claim 2, wherein the perfluoropolyether oils
are selected from the following classes:
E--O--(CF.sub.2CF(CF.sub.3)O).sub.m'(CFXO).sub.n'--E' (1) wherein:
X is equal to F or CF.sub.3; E and E', equal to or different from
each other, are selected from CF.sub.3, C.sub.2F.sub.5 or
C.sub.3F.sub.7, one fluorine atom of one or both the end groups
being replaceable with Cl and/or H; m' and n' are integers such
that the ratio m'/n' is between 20 and 1,000, n' being different
from zero; the units being statistically distributed along the
backbone, the viscosity of the product being within the above
range; C.sub.3F.sub.7O(CF(CF.sub.3)CF.sub.2O).sub.o, --D (2)
wherein: D is equal to --C.sub.2F.sub.5 or --C.sub.3F.sub.7, one
fluorine atom of one or both the end groups being replaceable with
Cl and/or H; o' is an integer such that the viscosity of the
product is within the above range; {C.sub.3,
F.sub.70--(CF(CF.sub.3)CF.sub.2O).sub.p'--CF(CF.sub.3)--}.sub.2 (3)
wherein: p' is an integer such that the viscosity of the compound
is within the above range, one F atom of one or both the end groups
C.sub.3F.sub.7 being replaceable with Cl and/or H;
E--O--(CF.sub.2CF(CF.sub.3)O
).sub.q'(C.sub.2F.sub.4O).sub.r'(CFX).sub.s'--E' (4) wherein: X is
equal to F or CF.sub.3; E and E', equal to or different from each
other, are as above; q', r' and s' are integers including 0, and
such that the viscosity of the product is within the above range;
E--O--(C.sub.2F.sub.4O).sub.t'(CF.sub.2O).sub.u'--E' (5) wherein: E
and E', equal to or different from each other, are as above; t' and
u' are integers such that the ratio t'/u' is between 0.1 and 5, u'
being different from 0 and the viscosity of the product is within
the above range; E--O--(CF.sub.2CF.sub.2CF.sub.2O).sub.v'--E' (6)
wherein: E and E', equal to or different from each other, are as
above; v' is a number such that the viscosity of the product is
within the above range; D--O--(CF.sub.2CF.sub.2O).sub.z'--D' (7)
wherein: D and D', equal to or different from each other, are
selected from C.sub.2F.sub.5 or C.sub.3F.sub.7, one fluorine atom
of one or both the end groups being replaceable with Cl and/or H;
z' is an integer such that the viscosity of the product is within
the above range
E.sub.1--O(CF.sub.2O).sub.n(CF.sub.2CF.sub.2O).sub.m--(CF.sub.2CF.sub.2CF-
.sub.2O).sub.p(CF.sub.2CF.sub.2CF.sub.2CF.sub.2O).sub.q--E.sub.2
(8) wherein: E.sub.1 and E.sub.2 are perfluoroalkyl end groups
equal to or different from each other, having formula
--(CF.sub.2).sub.zCF.sub.3 wherein z is an integer from 0 to 3; n,
m, p, q are integers equal to or different from each other
comprised between 0 and 100 and selected so that the viscosity of
the oil is within the above range and such that the ratio m/n is
between 2 and 20, n being different from 0; (p+q)/(n+m+p+q) is
between 0.05 and 0.2, (n+m+p+q) being different from 0; n/(n+m+p+q)
is between 0.05 and 0.40, (n+m+p+q) being different from 0.
4. Use according to claim 3, wherein the perfluoropolyether oils
are those of the classes (1), (4), (5), (8) or their mixtures and
those of the class (2) and (6).
5. Use according to claim 1, wherein the pour point depressant
additives are used in amounts ranging from 0.1% to 30% by weight
with respect to the final composition, preferably from 1% to 20%,
more preferably from 5% to 10%.
6. Use according to claim 1, wherein mixtures of additives of
general formula (I) and mixtures of perfluoropolyether oils are
used.
7. Lubricating compositions comprising from: A) 70% to 99.9% by
weight of at least a fluorinated oil, preferably a
perfluoropolyether oil having viscosity at 20.degree. C. between 10
and 4,000 cSt, preferably between 30 and 2,000 cSt, and comprising
one or more of the following repeating units: --CFXO-- wherein X is
equal to F or CF.sub.3; --CF.sub.2CF.sub.2O--,
--(C.sub.3F.sub.6O--, --CF.sub.2CF.sub.2CF.sub.2O--,
--CF.sub.2CF.sub.2CF.sub.2CF.sub.2O--, said units being
statistically distributed along the backbone; and B) 0.1% to 30% by
weight of at least an additive of formula (I).
8. Compositions according to claim 3 comprising at least an
additive of formula (I) and at least an oil of the classes (1),
(5); preferably an oil of class (5) having a viscosity between 30
cSt and 300 cSt.
9. Lubricating compositions according to claim 7 comprising
antirust, antiwear, antioxidant additives, suitable thermal
stabilizers for perfluoropolyether oils.
10. Use of the compounds (I) of claim 1 as lubricating oils having
a low pour point.
11. Perfluoropolyether lubricating oils of claim 10.
Description
[0001] The present invention relates to fluorinated derivatives
capable to lower the pour point temperature of lubricating
oils.
[0002] Specifically the invention relates to the use of
perfluoropolyether-based compounds as additives to reduce the pour
point temperature of fluorinated oils, in particular having a
perfluoropolyether structure, and to the lubricating compositions
comprising said additives.
[0003] It is known in the prior art to use perfluoropolyether oils
as lubricants in a wide temperature range, in particular in
applications where a good lubricating capability at very low
temperatures is required, for example in the aerospace and in the
refrigeration industry. Among these lubricants having a
perfluoropolyether structure available on the market, it can be
mentioned FOMBLIN.RTM. marketed by Solvay Solexis S.p.A., used as
lubricating oil at temperatures even lower than -80.degree. C.
[0004] It is also known that the lower limit at low temperatures of
lubricating oils, fluorinated and non fluorinated, is connected to
the temperature corresponding to their pour point, under which
their use requires a strong energy due to the difficulty to move
the lubricant itself. As a matter of fact in non fluorinated oils,
in correspondence of the pour point, crystallization takes place,
while in fluorinated oils, for example perfluoropolyether oils, a
sudden viscosity increase is observed.
[0005] To lower the pour point, it is also known to use "pour point
depressant" additives. For example non fluorinated additives, have
been developed for hydrogenated paraffins, for mineral oils and
petroleum. Such additives are generally hydrogenated polymers
miscible with the lubricating oil preventing the oil from
crystallizing as the temperature decreases without altering the
lubricating characteristics, and therefore the lubricant
performances of the oil. Examples of said additives are
polyalkylmethacrylates, polyacrylates, phthalates. For example,
patent application WO 89/01507 describes the use of "pour point
depressant" additives consisting of polymethacrylates having
molecular weight in the range 10,000-300,000 to lower the pour
point of paraffinic oils down to about -35.degree. C.
[0006] However the use of non fluorinated additives in fluorinated
oils, for example, perfluoropolyether oils, is not viable as said
additives are not miscible with fluorinated lubricants.
[0007] In the field of fluorinated oils, in particular of
perfluoropolyether oils, pour point depressant additives allowing
to lower the pour point are not available on the market.
[0008] The need was therefore felt to have available additives:
[0009] capable to lower the pour point of fluorinated lubricants,
in particular perfluoropolyether oils; [0010] soluble in
fluorinated oils, in particular perfluoropolyether oils; [0011] not
substantially altering the lubricating characteristics of the
fluorinated oil, in particular of the perfluoropolyether oil, for
example viscosity, evaporation loss, chemical stability, viscosity
index, in particular not altering the viscosity index; so as to
widen the thermal rating at low temperatures of said fluorinated
lubricants, preferably perfluoropolyether lubricants.
[0012] The Applicant has unexpectedly and surprisingly found that
the addition of particular fluorinated compounds, to
perfluoropolyether oils, allows to lower the pour point temperature
of said oils and to solve the above technical problem.
[0013] It is-an object of the present invention the use as pour
point depressant additives for fluorinated oils, preferably
perfluoropolyether oils, of compounds having the following
structure:
X.sub.1--O(CF.sub.2.sub.O).sub.n(CF.sub.2CF.sub.2O).sub.m(CF.sub.2CF.sub.-
2CF.sub.2O).sub.p(CF.sub.2CF.sub.2CF.sub.2CF.sub.2O).sub.q--X.sub.2
(I) wherein: [0014] the repeating units --CF.sub.2O--,
--CF.sub.2CF.sub.2O--, --CF.sub.2CF.sub.2CF.sub.2O--,
--CF.sub.2CF.sub.2CF.sub.2CF.sub.2O-- are statistically distributed
along the chain; [0015] --X.sub.1 and --X.sub.2 are perfluoroalkyl
chain end groups equal to or different from each other, having
formula --(CF.sub.2).sub.zCF.sub.3 wherein z is an integer from 0
to 3; [0016] n is an integer from 1 to 200, [0017] m is an integer
from 0 to 200, [0018] p, q are integers from 0 to 10, preferably
from 0 to 5, more preferably from 0 to 1, still more preferably 0,
with the proviso that: [0019] the ratio (p+q)/(p+q+m+n) is lower
than or equal to 0.05, being also equal to 0, (p+q+m+n) being
different from 0; [0020] the ratio m/n, when n is different from 0,
is lower than or equal to 0.7, preferably lower than 0.5, more
preferably lower than 0.35; [0021] the number average molecular
weight of the compounds (I) ranges from 1,000 to 10,000, preferably
from 2,000 to 8,000, more preferably from 2,400 to 5,000.
[0022] The additives of the invention at .sup.19F NMR analysis do
not show chlorine atoms, the latter being substantially absent.
With compounds of formula (I) wherein the chlorine atoms,
determined by .sup.19F NMR, are substantially absent, compounds are
meant wherein the chlorine atoms are lower than the sensitivity
limit of the analytical method .sup.19F NMR.
[0023] The additives of formula (I) are added to fluorinated oils,
preferably perfluoropolyether oils having viscosity at 20.degree.
C. between 10 and 4,000 cSt, preferably between 30 and 2,000 cSt,
and containing one or more of the following repeating units:
--CFXO--, wherein X is equal to F or CF.sub.3;
--CF.sub.2CF.sub.2O--, --(C.sub.3F.sub.6O)--,
--CF.sub.2CF.sub.2CF.sub.2O--,
--CF.sub.2CF.sub.2CF.sub.2CF.sub.2O--, said units being
statistically distributed along the backbone.
[0024] Said perfluoropolyether oils are preferably selected from
the following classes: E--O--(CF.sub.2CF(CF.sub.3)
O).sub.m'(CFXO).sub.n'--E' (1) [0025] wherein: [0026] X is equal to
F or CF.sub.3; [0027] E and E', equal to or different from each
other, are selected from CF.sub.3, C.sub.2F.sub.5 or
C.sub.3F.sub.7, one fluorine atom of one or both the end groups
being replaceable with Cl and/or H; m' and n' are integers such
that the ratio m'/n' is between 20 and 1,000, n' being different
from zero; the units being statistically distributed along the
backbone, the viscosity of the product being within the above
range. [0028] These polymers can be obtained by perfluoropropene
photooxidation as described in GB 1,104,432, and by subsequent
conversion of the end groups as described in GB 1,226,566;
C.sub.3F.sub.7O(CF(CF.sub.3)CF.sub.2O).sub.o'--D (2) [0029]
wherein: [0030] D is equal to --C.sub.2F.sub.5 or --C.sub.3F.sub.7,
one fluorine atom of one or both the end groups being replaceable
with Cl and/or H; o' is an integer such that the viscosity of the
product is within the above range. [0031] These polymers can be
prepared by ionic oligomerization of the perfluoropropylenoxide and
subsequent treatment with fluorine as described in U.S. Pat. No.
3,242,218;
{C.sub.3F.sub.7O--(CF(CF.sub.3)CF.sub.2O).sub.p',--CF(CF.sub.3)--}.sub.2
(3) [0032] wherein: [0033] p' is an integer such that the viscosity
of the product is within the above range, one F atom of one or both
the end groups C.sub.3F.sub.7 being replaceable with Cl and/or H.
These products can be prepared by ionic telomerization of the
perfluoropropylenoxide and subsequent photochemical dimerization as
reported in U.S. Pat. No. 3,214,478;
E--O--(CF.sub.2CF(CF.sub.3)O).sub.q'(C.sub.2F.sub.4O).sub.r'(CFX).sub.s',-
--E' (4) [0034] wherein: [0035] X is equal to F or CF.sub.3; [0036]
E and E', equal to or different from each other, are as above;
[0037] q', r' and s' are integers including 0, and such that the
viscosity of the product is within the above range. [0038] These
polymers are obtainable by photooxidation of a mixture of
C.sub.3F.sub.6 and C.sub.2F.sub.4 and subsequent treatment with
fluorine as described in U.S. Pat. No. 3,665,041;
E--O--(C.sub.2F.sub.4O ).sub.t',(CF.sub.2O).sub.u'--E' (5) [0039]
wherein: [0040] E and E', equal to or different from each other,
are as above; [0041] t' and u' are integers such that the ratio
t'/u' is between 0.1 and 5, u' being different from 0 and the
viscosity of the product is within the above range. [0042] These
polymers are obtained by photooxidation of C.sub.2F.sub.4 as
reported in U.S. Pat. No. 3,715,378 and subsequent treatment with
fluorine as described in U.S. Pat. No. 3,665,041;
E--O--(CF.sub.2CF.sub.2CF.sub.2O).sub.V'--E' (6) [0043] wherein:
[0044] E and E', equal to or different from each other, are as
above'; [0045] v' is a number such that the viscosity of the
product is, within the above range. [0046] These polymers are
obtained as described in EP 148,482;
D--O--(CF.sub.2CF.sub.2O).sub.z'--D' (7) [0047] wherein: [0048] D
and D', equal to or different from each other, are selected from
C.sub.2F.sub.5 or C.sub.3F.sub.7, one fluorine atom of one or both
the end groups being replaceable with Cl and/or H; z' is an integer
such that the viscosity of the product is within the above range.
These polymers can be obtained as reported in U.S. Pat. No.
4,523,039; E.sub.1--O(CF.sub.2O).sub.n
(CF.sub.2CF.sub.2O).sub.m--(CF.sub.2CF.sub.2CF.sub.2O).sub.p(CF.sub.2CF.s-
ub.2CF.sub.2CF.sub.2O).sub.q--E.sub.2 (8) [0049] wherein: [0050]
E.sub.1 and E.sub.2 are perfluoroalkyl end groups, equal to or
different from each other, having formula
--(CF.sub.2).sub.zCF.sub.3 wherein z is an integer from 0 to 3;
[0051] n, m, p, q are integers equal to or different from each
other comprised between 0 and 100 and selected so that the
viscosity of the oil is within the above range and such that the
ratio m/n is between 2 and 20, n being different from 0;
(p+q)/(n+m+p+q) is between 0.05 and 0.2, (n+m+p+q) being different
from 0; n/(n+m+p+q) is between 0.05 and 0.40 (n+m+p+q) being
different from 0. These polymers can be obtained according to EP
1,454,938. [0052] The preferred perfluoropolyether oils are those
of the classes (1), (4), (5), (8) or their mixtures and are
available on the market as FOMBLIN.RTM. marketed by Solvay Solexis
and those of the classes (2), (6).
[0053] The additives of the present invention are used in amounts
ranging from 0.1% to 30% by weight with respect to the final
composition, preferably from 1% to 20%, more preferably from 5% to
10%.
[0054] A further object of the present invention are lubricating
compositions comprising (% by weight) from: [0055] A) 70% to 99.9%
by weight of at least a fluorinated oil, preferably a
perfluoropolyether oil having viscosity at 20.degree. C. between 10
and 4,000 cSt, preferably between 30 and 2,000 cSt, and comprising
one or more of the following repeating units: [0056]
--CFXO--wherein X is equal to F or
CF.sub.3;--CF.sub.2CF.sub.2O--,--(C.sub.3F.sub.6O)--,
--CF.sub.2CF.sub.2CF.sub.2O--,
--CF.sub.2CF.sub.2CF.sub.2CF.sub.2O--, said units being
statistically distributed along the backbone; and [0057] B) 0.1% to
30% by weight of at least an additive of formula In these
compositions mixtures of perfluoropolyether oils and mixtures of
additives of general formula (I) can be used.
[0058] The compositions comprising an additive of formula (I) and
at least an oil of the classes (1), (5) are particularly preferred;
the compositions comprising the oils of the class (5) having a
viscosity at 20.degree. C. between 30 cSt and 300 cSt are more
preferred.
[0059] The lubricating compositions of the present invention show a
pour point lower than that of the non additivated oil.
[0060] The lubricating compositions of the present invention having
a pour point lower than -950.degree. C. are particularly useful in
aerospace applications; this low pour point represents an
improvement with respect to the perfluoropolyether oils available
on the market.
[0061] The compositions of the present invention show a pour point
temperature preferably lower of at least 4.degree. C. with respect
to the one of the perfluoropolyether lubricant contained therein,
corresponding to a decrease of at least St with respect to the pour
point temperature of the non additived oil (see the comparative
Examples).
[0062] Furthermore the compositions of the invention are limpid as
it has been found that the additives of formula (I) are completely
soluble in the perfluoropolyether oils and therefore said
compositions are thermodynamically stable. This is particularly
advantageous as there are no phase separation problems during the
storage.
[0063] The invention lubricating compositions can also comprise the
additives commonly used in perfluoropolyether oils, such as for
example antirust, antiwear, antioxidant additives, thermal
stabilizers.
[0064] The use of the lubricating compositions of the invention, as
said, is particularly advantageous in applications wherein a
lubricating capability at a very low operating temperature is
required, for example in aerospace applications, in the
refrigeration and in equipments under vacuum used at low
temperatures.
[0065] The Applicant has furthermore found that the additives of
the present invention, besides being liquid at the temperature of
20.degree. C. and having a low vapour pressure, also show a high
viscosity index and a pour point lower than -90.degree. C.,
preferably lower than -95.degree. C., more preferably lower than
-100.degree. C. Therefore said additives can be used also as
lubricating oils per se.
[0066] A further object of the present invention is the use of
compounds (I) as lubricating oils having a low pour point.
[0067] The compounds of formula (I) can be prepared, for example,
according to the following process comprising the following steps:
[0068] a) synthesis of a peroxidic perfluoropolyether, obtainable
by one of the following reactions: [0069] a1) tetrafluoroethylene
(TFE) photooxidation, in the presence of UV light, at a temperature
between -40.degree. C. and -100.degree. C., in solvents liquid
under the reaction conditions, of formula:
C.sub.yF(.sub.2y+2-x)H.sub.X (II) [0070] wherein y is an integer
from 2 to 4; x is an integer equal to 0 or 1; [0071] in the
presence of elemental fluorine as chain transfer agent, diluted
with an inert gas; or [0072] a2) TFE oxidation by using as radical
initiator fluorine or hypofluorites of formula R.sub.fOF (III)
[0073] R.sub.f being a perfluoroalkyl radical from 1 to 3 carbon
atoms, [0074] by operating in the temperature range from
-40.degree. C. to -100.degree. C. at a pressure between 0 and 12
bar, in an inert solvent; [0075] preferably a2) is used; [0076] b)
thermal treatment of the peroxidic product obtained in step a) at a
temperature from 150.degree. C. to 250.degree. C., optionally in
the presence of chain transfer agent selected from elemental
fluorine, and one or more hypofluorites of formula (III); [0077] c)
treatment with elemental fluorine of the polymer obtained in b) at
temperatures from 100.degree. C. to 250.degree. C., or by treatment
with fluorine in the presence of UV radiations, by operating at
temperatures between -50.degree. C. and 120.degree. C. In step a1)
generally the fluorine is added in amounts such that the molar
ratio fluorine/tetrafluoroethylene is between 210.sup.-2 and
1.210.sup.-3, preferably between 1.210.sup.-2 and 1.710.sup.-3 and
is diluted with an inert gas in ratios by volume from 1/50 to
1/1,000.
[0078] In step a1) preferably the solvents are the following:
perfluoropropane (C.sub.3F.sub.8), hydropentafluoroethane
(C.sub.2F.sub.5H) and 2-hydroheptafluoropropane
(CF.sub.3CFHCF.sub.3), C.sub.4F.sub.9H (for example CF.sub.3C
-FHCF.sub.2CF.sub.3, (CF.sub.3).sub.3CH,
HCF.sub.2CF.sub.2CF.sub.2CF.sub.3).
[0079] The solvent used in step al) is liquid at the synthesis
temperatures (-40.degree./-80.degree. C.) and solubilizes the
peroxidic polymer even in high molecular weights forming a
homogeneous solution. This represents a remarkable advantage since
there is no separation of the peroxidic polymer. This makes
possible the industrial use of said process as no cloggings of the
industrial plant piping due to uncontrolled viscosity increase take
place. Further the thermal exchanges are extremely effective and
this avoids uncontrolled degradation of the peroxidic polymer.
[0080] Besides the solvents used in step a1) allow a high reaction
kinetics, so to maintain high productivities combined with a low
peroxidic content in the polymer, lower than 4-5 g of active
oxygen/100 g of product, to avoid explosion risks.
[0081] As said, the fluorine used in step a1) must be diluted with
a gas. Generally an inert gas, such as nitrogen or helium is used.
Oxygen can also be used as diluent. In fact, when undiluted
fluorine is used, the fluorine produces uncontrolled. local
reactions and gaseous decomposition products. The latter cause
stopping of the process due to the fouling of the reactor and of
the optical system (UV lamp), in case of polymerization in the
presence of UV radiations. Besides, in these cases, an uncontrolled
increase of the P.O., higher than 4-5 g of active oxygen/100 g of
product can take place, bringing to explosion risks in the system.
When it is used diluted, the fluorine acts in step a1) as chain
transfer agent with a very high selectivity, of the order of 90%.
The fluorine furthermore, in step a1), reduces and substantially
eliminates the reaction induction times avoiding the use of
reaction activators.
[0082] In step a2), wherein the TFE oxidation is carried out
without using the UV light, the solvents can be those above
mentioned, or chlorinated solvents. For example CF.sub.2Cl.sub.2,
optionally in admixture with COF.sub.2 can be mentioned.
[0083] In step a2) the molar ratio TFE/chemical initiator ranges
from 10 to 200, preferably from 40 to 120.
[0084] In step b) the use of chain transfer agents can be omitted
when the control of the molecular weight is not necessary. This
happens, for example, when the viscosity of the peroxidic product
is lower than 5,000 cSt at 20.degree. C.
[0085] In step b) generally the fluorine or the hypofluorites of
formula (III), when present, are used with a flow-rate from
110.sup.-2 to 3 moles h/Kg polymer, preferably from 210.sup.-2 to
2.
[0086] Step a) and step b) of the process of the present invention
can be carried out in a discontinous, semicontinuous or continuous
way.
[0087] Step b) ends when the peroxidic content in the polymer is
substantially absent. This means that the P.O. value is equal to or
lower than the sensitivity limit of the analytical method used (1
ppm) which consists in the titration with thiosulphate of the
iodine developed by the reaction of the peroxidic polymer with
sodium iodide. Generally the thermal treatment times are from 10 to
30 hours, depending on the P.O. and the temperature used in this
step.
[0088] Step c) is usually carried out in a discontinuous way. The
reaction ends when, at .sup.19F NMR analysis, the functional end
groups (mainly --OCF.sub.2COF and --OCOF) have been transformed
into perfluoroalkyl end groups (method sensitivity limit: 1 meq/Kg
polymer).
[0089] In step c) the fluorine is fed in amounts so to have a
concentration in the perfluoropolyether generally corresponding to
the fluorine solubility limit. At the temperature used in this
step, it is of the order of 10.sup.-2 moles of fluorine/ litre of
polymer.
[0090] Optionally, the product can be distilled to obtain fractions
having a given number average molecular weight and a determined
distribution of the molecular weights.
[0091] Some illustrative but not limitative Examples of the present
invention follow.
EXAMPLES
Characterization:
[0092] Determination of the Pour Point Temperature: [0093] It has
been carried out by using the ASTM D 97 method. [0094] The reported
results are the average of 5 tests.
[0095] Determination of the Kinematic Viscosity: [0096] It has been
carried out according to the ASTM D 445 method.
[0097] Determination of the Viscosity Index: [0098] It has been
carried out according to the ASTM D 2270 method. The higher the
viscosity index, the lower is the viscosity variation as the
temperature changes.
Example 1
[0099] 95 g of a perfluoropolyether oil of the class (5),
commercially known with the name Fomblin.RTM. Z25, having kinematic
viscosity at 20.degree.C. of 255 cSt, viscosity index equal to 356
and pour point of -74.degree. C., are additioned with 5 g of an
additive of formula (I) having number average molecular weight of
2,467, m/n=0.33 and p+q/(p+q+m+n)=0.016.
[0100] The pour point of the obtained composition is determined
according to the above method and is equal to -82.degree. C. The
viscosity index of said composition is equal to 348.
[0101] Therefore the obtained lubricating composition shows a pour
point of SOC lower than that of the basic perfluoropolyether oil,
corresponding to a pour point temperature decrease of about
11%.
[0102] It is to be noted that the addition of the additive (I) of
the present invention to the perfluoropolyether oil does not alter
the lubricant nature since the viscosity index of the obtained
lubricating composition is subsantially equal to that of the basic
oil.
Example 2
[0103] The Example 1 was repeated by using an additive of formula
(I) having number average molecular weight of 3,777, m/n=0.31 and
p+q/(p+q+m+n)=0.016.
[0104] The pour point of the obtained mixture is determined
according to the above method and is equal to -80.degree. C.
[0105] Therefore the obtained lubricting composition shows a pour
point of 6.degree. C. lower than that of the basic
perfluoropolyether oil corresponding to a pour point temperature
decrease equal to about 8%.
Example 3 (Comparative)
[0106] The Example 1 was repeated by using as an additive a
compound having formula (I) and number average molecular weight of
4,000 but having m/n=0.8.
[0107] The pour point of the obtained mixture is determined
according to the above method and is equal to -76.degree. C.
[0108] Therefore the obtained lubricating composition shows a pour
point of only 3.degree. C. lower than that of the basic
perfluoropolyether oil. Such temperature variation corresponds to a
decrease of about 3%.
Example 4
[0109] 90 g of a perfluoropolyether oil of class (5), commercially
known as Fomblin.RTM. Z03, having kinematic viscosity at 20.degree.
C. of 30 cSt and pour point of -93.degree. C., are additioned with
10 g of an additive having formula (I), wherein the number average
molecular weight is 2,467, m/n=0.33 and p+q/(p+q+m+n)=0.016.
[0110] The pour point of the obtained mixture is determined
according to the above method and is equal to -102.degree. C.
[0111] Therefore the obtained lubricating composition shows a pour
point of 11.degree. C. lower than that of the basic
perfluoropolyether oil corresponding to a decrease of 10%.
Example 5
[0112] The Example 1 was repeated by using an additive having
formula (I) wherein the number average molecular weight is 3,777;
m/n=0.31 and p+q/(p+q+m+n)=0.016.
[0113] The pour point of the obtained mixture is determined
according to the above method and is equal to -99.degree. C.
[0114] Therefore the lubricating composition of the Example shows a
pour point of 6.degree. C. lower than that of the basic
perfluoropolyether oil corresponding to a decrease of 6%.
Example 6
[0115] The Example 1 was repeated but by using as lubricant the
perfluoropolyether oil of structure (6) and commercially known as
Demnum.RTM. S-20, having a viscosity of 53 cSt and a pour point of
-75.degree. C. determined with the above method.
[0116] The pour point of the obtained mixture is determined
according to the above method and is equal to -79.degree. C.
[0117] Therefore the obtained lubricating composition shows a pour
point of 4.degree. C. lower than that of the basic
perfluoropolyether oil corresponding to a decrease of 6%.
Example 7 (Comparative)
[0118] The Example 6 was repeated but by using as additive a
compound having formula (I) and number average molecular weight of
4,000 but wherein m/n=0.8.
[0119] The pour point of the obtained mixture is determined
according to the above method and is equal to -75.degree. C.
[0120] Therefore the obtained lubricating composition shows a pour
point equal to that of the basic perfluoropolyether oil.
Example 8
[0121] The Example 4 was repeated but by using as lubricating oil
the perfluoropolyether oil of structure (6) and commercially known
as Demnum.RTM. S-200, having a viscosity of 500 cSt and a pour
point of -53.degree. C. determined with the above method.
[0122] The pour point of the obtained mixture is determined
according to the above method and is equal to -63.degree. C.
[0123] Therefore the obtained lubricating composition shows a pour
point of 10.degree. C. lower than that of the basic
perfluoropolyether oil corresponding to a decrease of 19%.
Example 9
[0124] The Example 1 was repeated but by using as lubricant the
perfluoropolyether oil of structure (2) and commercially known as
Krytox.RTM. 1506, having a viscosity of 60 cSt and a pour point of
-47.degree. C. determined with the above method.
[0125] The pour point of the obtained mixture is determined
according to the above method and is equal to -51.degree. C.
[0126] Therefore the obtained lubricating composition shows a pour
point of 4.degree. C. lower than that of the basic
perfluoropolyether oil corresponding to a decrease of 9%.
Example 10
[0127] The Example 9 was repeated but changing the mixture
composition by using 90 g of oil and 10 g of additive.
[0128] The pour point of the obtained mixture is determined
according to the above method and is equal to -56.degree. C.
[0129] Therefore the obtained lubricating composition shows a pour
point of 90.degree. C. lower than that of the basic
perfluoropolyether oil corresponding to a decrease of 19%. Example
11
[0130] The Example 1 additive was subjected to characterization
from which the following properties resulted: TABLE-US-00001
viscosity at 20.degree. C.: 13 cSt; viscosity at -60.degree. C.:
344 cSt; viscosity index: 381; pour point: -111.degree. C.
[0131] From the above reported data it is evident that the
compounds of formula (I) can also be used as lubricating oils per
se, in particular in applications wherein a lubrication at a very
low temperature is required. TABLE-US-00002 TABLE 1 OIL ADDITIVE
Pour Pour Point Point (PP) PP Commercial (PP) % wt. % wt.
Composition Reduction EXAMPLE Name (.degree. C.) oil oil Type
(.degree. C.) (in %) 1 Fomblin .RTM. Z 25 -74 95 5 (I) -82 11 2
Fomblin .RTM. Z 25 -74 95 5 (I) -80 8 3 Fomblin .RTM. Z 25 -74 95 5
(I) with -76 3 (comp) m/n > 0.7 4 Fomblin .RTM. Z 03 -93 90 10
Ex. 1 -102 10 5 Fomblin .RTM. Z 03 -93 90 10 Ex. 2 -99 6 6 Demnum
S20 -75 95 5 Ex. 1 -79 6 7 Demnum S20 -75 95 5 Ex. 3 -75 0 (comp) 8
Demnum S200 -53 90 10 Ex. 1 -63 19 9 Krytox 1506 -47 95 5 Ex. 1 -51
9 10 Krytox 1506 -47 90 10 Ex. 1 -56 19
* * * * *