U.S. patent application number 15/533131 was filed with the patent office on 2017-12-21 for high conductivity fluid for air compressor applications.
The applicant listed for this patent is The Lubrizol Corporation. Invention is credited to Mark R. Baker, Carrie S. Briggs, Casey R. Fiting, Michael G. Foster.
Application Number | 20170362525 15/533131 |
Document ID | / |
Family ID | 54848915 |
Filed Date | 2017-12-21 |
United States Patent
Application |
20170362525 |
Kind Code |
A1 |
Foster; Michael G. ; et
al. |
December 21, 2017 |
HIGH CONDUCTIVITY FLUID FOR AIR COMPRESSOR APPLICATIONS
Abstract
The disclosed technology relates to a lubricant composition
containing a polyalkylene glycol in which greater than 50% of the
repeating units in the polyalkylene glycol contain an alkylene
oxide derived moiety comprising a C4 or greater alkyl group. The
lubricant compositions are particularly useful in compressors, such
as a reciprocating rotary vane, scroll, or rotary screw air
compressor.
Inventors: |
Foster; Michael G.;
(Midland, MI) ; Baker; Mark R.; (Midland, MI)
; Briggs; Carrie S.; (Bay City, MI) ; Fiting;
Casey R.; (Saginaw, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Lubrizol Corporation |
Wickliffe |
OH |
US |
|
|
Family ID: |
54848915 |
Appl. No.: |
15/533131 |
Filed: |
December 2, 2015 |
PCT Filed: |
December 2, 2015 |
PCT NO: |
PCT/US2015/063418 |
371 Date: |
June 5, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62087384 |
Dec 4, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 2203/10 20130101;
C10M 2207/2835 20130101; C10M 2203/06 20130101; C10N 2030/28
20200501; C10M 145/32 20130101; C10M 2205/0285 20130101; C10M
2209/104 20130101; C10N 2040/30 20130101; C10M 2219/044 20130101;
C10M 2209/1065 20130101; C10M 2209/1055 20130101; C10M 2207/2805
20130101; C10M 2209/1045 20130101; C10M 2209/106 20130101; C10M
2207/2825 20130101; C10M 2209/105 20130101; C10M 2203/108 20130101;
C10M 2207/401 20130101; C10M 2207/40 20130101; C10M 107/34
20130101; C10M 2203/1006 20130101 |
International
Class: |
C10M 107/34 20060101
C10M107/34; C10M 145/32 20060101 C10M145/32 |
Claims
1. A lubricant composition comprising: (a) at least one oil of
lubricating viscosity, and (b) at least one C.sub.4 or greater
polyalkylene glycol, wherein greater than 50% of the repeating
units in said at least one C.sub.4 or greater polyalkylene glycol
contain an alkylene oxide derived moiety comprising C.sub.4 or
greater alkyl.
2. The lubricant of claim 1, wherein less than 50% of the repeating
units in said at least one C.sub.4 or greater polyalkylene glycol
contain an alkylene oxide derived moiety comprising at least one
C.sub.1, C.sub.2, C.sub.3 alkyl group or combinations thereof.
3. The lubricant of claim 1, wherein said C.sub.4 or greater
polyalkylene glycol of component (b) is soluble in the oil of
lubricating viscosity.
4. The lubricant of clami 1, wherein said C.sub.4 or greater
polyalkylene glycol of component (b) is present at 5 percent by
weight or greater.
5. The lubricant of claim 1, further comprising at least one
C.sub.1 to C.sub.3 polyalkylene glycol, wherein greater than 50% of
the repeat units in said at least one C.sub.1 to C.sub.3
polyalkylene glycol contains an alkylene oxide derived moiety
comprising at least one of a C.sub.1, C.sub.2, or C.sub.3 alkyl
group or combination thereof.
6. The lubricant of claim 5, wherein the ratio of the at least one
C.sub.4 or greater polyalkylene glycol to the at least one C.sub.1
to C.sub.3 polyalkylene glycol is from about 1:1 to about 10:1 by
weight.
7. The lubricant of claim 1 wherein the oil of lubricating
viscosity comprises a mineral oil base oil.
8. The lubricant of claim 1 wherein the oil of lubricating
viscosity comprises an ester base oil.
9. The lubricant of claim 8, wherein the ester base oil comprises
at least one of esters of dicarboxylic acids; esters made from
C.sub.5 to C.sub.12 monocarboxylic acids and polyols, C.sub.5 to
C.sub.12 monocarboxylic acids and polyol ethers, C.sub.5 to
C.sub.12 monocarboxylic acids and vegetable oil esters, or mixtures
thereof.
10. The lubricant of claim 1 wherein the oil of lubricating
viscosity comprises a polymerized and/or interpolymerized olefin
base oil.
11. The lubricant of claim 10, wherein the polymerized and/or
interpolymerized olefin base oil is a polyalphaolefin base oil
12. The lubricant of claim 1, further comprising (d) other
additives.
13. The lubricant of claim 12, wherein the other additive comprises
at least one (i) antioxidant, (ii) corrosion inhibitor, (iii) metal
deactivator, or (iv) combinations thereof.
14. The lubricant of claim 13, wherein the other additives
comprises at least one antioxidant present from about 0.005 to
about 5 wt. %.
15. The lubricant of claim 13, wherein other additives comprises at
least one corrosion inhibitor present form about 0.005 to about 5
wt. %
16. The lubricant of claim 13, wherein other additives comprises at
least one metal deactivator present from about 0.001 to about 0.5
wt. %.
17. The lubricant of claim 13, wherein the lubricant composition
comprises from about 0.01 to about 10 wt. % of the at least one
C.sub.4 or greater polyalkylene glycol; an additive package
comprising from about 0.005 to about 5 wt. % of at least one
antioxidant, from about 0.005 to about 5 wt. % of at least one
corrosion inhibitor, and from about 0.001 to about 0.5 wt. % of at
least one metal deactivator; and the balance of at least one base
oil.
18. A method of operating an air compressor comprising lubricating
said air compressor with a lubricant composition comprising (a) at
least one oil of lubricating viscosity, and (b) at least one
C.sub.4 or greater polyalkylene glycol, wherein greater than 50% of
the repeating units in said at least one C.sub.4 or greater
polyalkylene glycol contain a C.sub.4 or greater alkylene oxide
moiety.
19. A method of maintaining the conductivity of a compressor
lubricant through multiple heat cycles, comprising lubricating said
air compressor with a lubricant composition comprising (a) at least
one oil of lubricating viscosity, and (b) at least one C.sub.4 or
greater polyalkylene glycol, wherein greater than 50% of the
repeating units in said at least one C.sub.4 or greater
polyalkylene glycol contain a C.sub.4 or greater alkylene oxide
moiety.
20. (canceled)
21. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] The disclosed technology relates to a lubricant composition
containing a polyalkylene glycol in which greater than 50% of the
repeating units in the polyalkylene glycol contain an alkylene
oxide derived moiety comprising a C.sub.4 or greater alkyl group.
The lubricant compositions are particularly useful in compressors,
such as a reciprocating rotary vane, scroll, or rotary screw air
compressor.
[0002] Lubricating oils have been used in the past to lubricate the
bearings of positive displacement compressors, to seal the rotors,
and to cool the compressed gases. Lubricating oils typically used
in the industry comprise a mineral oil or synthetic oil as a base
oil, and various additives for a particular purpose. Oxidation
stability and varnish and deposit control are some of the important
properties desirable in a lubricant for maximizing the life of the
lubricant, and hence, the life of the equipment, especially under
the high temperature and pressure conditions that can be created
when operating a positive displacement compressor, for example.
[0003] A known issue with air compressors is fires and possible
explosions.
[0004] U.S. Pat. No. 6,127,324 to Tolfa et al., issued Oct. 3,
2000, provides a lubricating basestock or lubricant composition for
use in a positive displacement compressor, where the basestock or
lubricant contains a blend of a polyalkylene glycol and an alkyl
aromatic. The '324 patent does not teach the prevention of fires or
explosions in compressors or any direction on preparing a
composition for preventing fires or explosions in compressors.
[0005] WO2001/90232A2 to Union Carbide Chemicals, published 29 Nov.
2001, provides a method for improving the fire resistance of
fluids. The fire resistance is directed to the fluid itself as
measured by a spray flammability test. Although the WO '232
publication teaches a fire resistant fluid, it does not teach how
to prevent fires or explosions in compressors in the first
instance, or any direction on preparing a composition to preventing
fires or explosions in compressors.
[0006] US Publication No. 2014/0249063 to Dow Global Technologies
LLC, published Sep. 4, 2014, provides an oil soluble polyalkylene
glycol. It is taught in the reference that the oil soluble
polyalkylene glycol can be employed in hydrocarbon oils, but does
not specify for what applications or what expected properties.
[0007] A need exists to prevent the ignition of fires or explosions
in compressors.
SUMMARY OF THE INVENTION
[0008] The inventors have found that the ignition of fires and/or
explosions in compressors may be due to electrical charge buildup
in the fluid used in the compressor. Without being bound by theory,
it is believed one way to solve this problem may be to increase the
electrical conductivity of the fluid to help dissipate the
electrical charge building up in the compressor. The inventors have
found that known anti-static additives do not work in compressors.
For example, most commercial anti-static additives lose
conductivity properties when subjected to the heating that occurs
in such compressors.
[0009] The disclosed technology therefore provides, in one aspect,
a lubricant compostion containing (a) at least one oil of
lubricating viscosity, and (b) at least one C.sub.4 or greater
polyalkylene glycol. Greater than 50% of the repeating units in the
C.sub.4 or greater polyalkylene glycol contain an alkylene oxide
derived moiety comprising a C.sub.4 or greater alkyl.
[0010] In an embodiment, less than 50% of the repeating units in
the at least one C.sub.4 or greater polyalkylene glycol can contain
an alkylene oxide derived moiety comprising at least one C.sub.1,
C.sub.2, C.sub.3 alkyl group or combinations thereof.
[0011] In a further embodiment, the at least one C.sub.4 or greater
polyalkylene glycol of component (b) is soluble in the oil of
lubricating viscosity.
[0012] In another embodiment, the at least one C.sub.4 or greater
polyalkylene glycol of component (b) can be present in the
lubricant composition at about 5 percent by weight or greater, such
as, for example, from about 5 to about 15 percent by weight.
[0013] In embodiments, the lubricant composition can further
include at least one C.sub.1 to C.sub.3 polyalkylene glycol.
Greater than 50% of the repeat units in the at least one C.sub.1 to
C.sub.3 polyalkylene glycol can contain an alkylene oxide derived
moiety having at least one of a C.sub.1, C.sub.2, or C.sub.3 alkyl
group or combination thereof.
[0014] In some embodiments, the ratio of the at least one C.sub.4
or greater polyalkylene glycol to the at least one C.sub.1 to
C.sub.3 polyalkylene glycol can be from about 1:1 to about 10:1 by
weight.
[0015] In further embodiments, the oil of lubricating viscosity in
the lubricant composition can be a mineral oil. In the same, or
different embodiments, the oil of lubricating viscosity in the
lubricant composition can be an ester.
[0016] The lubricant composition can, in some embodiments, contain
(d) other additives. The other additives can be any of those
commonly employed in compressor lubricants.
[0017] Another aspect of the present technology is a method of
operating an air compressor. The method can include lubricating the
air compressor with a lubricant composition containing (a) at least
one oil of lubricating viscosity, and (b) at least one C.sub.4 or
greater polyalkylene glycol, wherein greater than 50% of the
repeating units in the C.sub.4 or greater polyalkylene glycol
contain an alkylene oxide derived moiety comprising a C.sub.4 or
greater alkyl.
[0018] In a further aspect of the technology there is provided the
use of a polyalkylene glycol in a lubricant for an air compressor,
wherein greater than 50% of the repeating units in the C.sub.4 or
greater polyalkylene glycol contain an alkylene oxide derived
moiety comprising a C.sub.4 or greater alkyl.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Various preferred features and embodiments will be described
below by way of non-limiting illustration.
[0020] In one aspect, the disclosed technology provides a lubricant
composition containing (a) at least one oil of lubricating
viscosity, and (b) at least one C.sub.4 or greater polyalkylene
glycol.
C.sub.4 or Greater Polyalkylene Glycol
[0021] Polyalkylene glycols have the general formula
HO--(R.sub.1--O).sub.n--H, where R.sub.1 is an alkyl group,
R.sub.1--O represents an alkylene oxide derived moiety, and
(R.sub.1--O).sub.n represents a repeating unit. The lubricant
composition comprises at least one C.sub.4 or greater polyalkylene
glycol. By "C.sub.4 or greater polyalkylene glycol," it is meant
that greater than 50% of the repeating units in the polyalkylene
glycol contain an alkylene oxide derived moiety having a C.sub.4 or
greater alkyl group. In some embodiments, more than 60%, or 70%, or
even 80% or 90% of the repeating units in the C.sub.4 or greater
polyalkylene glycol contain an alkylene oxide derived moiety having
a C.sub.4 or greater alkyl group. In an embodiment, 100% of the
repeating units in the C.sub.4 or greater polyalkylene glycol
contain an alkylene oxide derived moiety having a C.sub.4 or
greater alkyl group.
[0022] By "C.sub.4 or greater alkyl group" it is meant the alkyl
group has at least 4 carbon atoms, for example, from 4 to 8 carbon
atoms, or from 4 to 7 carbon atoms, or 4, 5 or 6 carbon atoms. The
C.sub.4 or greater alkyl group in the alkylene oxide derived moiety
may be straight chain or branched, and is preferably straight
chain.
[0023] The C.sub.4 or greater polyalkylene glycol can be a single
polyalkylene glycol, or a mixture of polyalkylene glycols. Thus,
the percentage of repeating units containing an alkylene oxide
derived moiety having a C.sub.4 or greater alkyl group can be
calculated based on a single polyalkylene glycol, or a mixture of
polyalkylene glycols. A mixture of polyalkylene glycols may contain
polyalkylene glycols in which less than 50% of the repeating units
therein contain an alkylene oxide derived moiety having a C.sub.4
or greater alkyl group and the mixture can still be considered a
C.sub.4 or greater polyalkylene glycol so long as the total number
of repeating units from all polyalkylene glycols in the mixture
containing an alkylene oxide derived moiety having a C.sub.4 or
greater alkyl group is greater than 50%.
[0024] In some embodiments, less than 50% of the repeating units in
the C.sub.4 or greater polyalkylene glycol contain an alkylene
oxide derived moiety having at least one of a C.sub.1, C.sub.2, or
C.sub.3 alkyl group or combinations thereof, or less than 40%, or
less than 30 or 20%, or even less than 10%. In some embodiments,
the C.sub.4 or greater polyalkylene glycol is completely free of
alkylene oxide derived moieties having any C.sub.1, C.sub.2, or
C.sub.3 alkyl groups.
[0025] In an embodiment, the C.sub.4 or greater polyalkylene glycol
can include units derived from butylene oxide to units derived from
propylene oxide from about 3:1 to about 1:1, such as, for example,
3:1, 2.7:1, 2.5:1, 2.3:1, 2.1:1, 1.9:1, 1.7:1, 1.5:1, 1.3:1, 1.1:1
or 1:1.
[0026] In some embodiments, the C.sub.4 or greater polyalkylene
glycol can have a carbon to oxygen ratio of at least 3.5:1, or of
at least 4:1, or in the alternative of at least 5:1, or of at least
6:1.
[0027] In some embodiments, the C.sub.4 or greater polyalkylene
glycol can have an unsaturation level of less than about 0.05
meq/g, or less than 0.04 meq/g, or in the alternative less than
0.03 meq/g.
[0028] The C.sub.4 or greater polyalkylene glycol has a number
average molecular weight of about 200 to about 8000, preferably
about 500 to 5000. Here, as well as elsewhere in the specification,
the ratio and range limits may be combined.
[0029] The polyaklyene glycol can have a kinematic viscosity at
40.degree. C. of about 15 to about 500 cSt, preferably of about 22
to about 500 cSt, more preferably of about 22 to about 370 cSt, and
most preferably of about 22 to about 220 cSt. In some embodiments,
polyaklyene glycol can have a kinematic viscosity at 40.degree. C.
of less than 100 cSt, or from about 5 to about 95 or 100, and in
some instances from about 10 to about 80 or 90.
[0030] In a preferred embodiment, the C.sub.4 or greater
polyalkylene glycol may be represented by the following
formula:
Z--(--(C.sub.3H.sub.6--R.sub.1--O).sub.n--R.sub.2).sub.m
wherein Z is a residue of a non-amine initiator having from 1-8
active hydrogens, and R.sub.1 is a C.sub.1 to C.sub.12 alkyl or
aromatic, such as, for example, a phenol or alkylated phenol, or a
C.sub.1 to C.sub.10 alkyl or aromatic, or even a C.sub.1 to C.sub.6
or C.sub.8 alkyl or aromatic, but preferably a C.sub.1, C.sub.2 or
C.sub.3 alkyl. The integer n has a value from 8 to 25, preferably
from 10 to 20. The number average molecular weight of the
polyalkylene glycol is from about 200 to about 8,000, preferably
from about 500 to about 5000. R2 is H, an alkyl having from about 1
about 30 carbons, preferably from about 1 to about 24 carbons, more
preferably from about 1 to about 12 carbons, and most preferably
from about 1 to about 6 carbons, or an acyl having from about 1 to
about 30 carbons, preferably from about 1 to about 24 carbons, more
preferably from about 1 to about 12, and most preferably from about
1 to about 6 carbons, and m is from 1 to 8.
[0031] Although the C.sub.4 or greater polyalkylene glycol can be
prepared in a number of ways, suitable examples of the C.sub.4 or
greater polyalkylene glycol are polyalkylene glycols prepared with
initiators containing from 1-8 active hydrogens prepared from
alkylene oxides having from 2 to about 12 carbons, including
ethylene oxide, propylene oxide or butylene oxide. The oxides may
be polymerized alone (homopolymers) or as mixtures (co- or tri-
polymers). Another suitable polyalkylene glycol is prepared from a
non-amine initiator having 1-4 active hydrogens, and having a
kinematic viscosity at 40.degree. C. of about 22 to about 220 cSt.
Commercially available examples of polyalkylene glycols used for
component (A) are WI 165.RTM. and WI 285.RTM., available at
BASF.
[0032] The meaning of the term "non-amine initiator" is explained
as follows. Polyalkylene glycols are polymeric products where the
monomers are epoxides of low carbon number olefins (ethylene,
propylene, and butylene oxides are the typical ones used). An
initiator must be used to start the polymerization reaction which
is used to prepare the polyalkylene glycol products.
[0033] The initiators are typically described as chemicals having
active hydrogens. This means chemicals which have hydrogens which
can be relatively easily removed with base. Active hydrogens are
ones which are bonded to heteroatoms (e.g. oxygen, nitrogen,
sulphur, phosphorous). It is common in the industry when making
polyalkylene glycols to use oxygen initiators, referred to as
non-amine initiators, (alcohols, water, diols, glycerols and/or
other polyols), although some products are made using nitrogen
initiators, referred to as amine initiators, (alkyl amines, aryl
amines, diamines, and polyamines). Sulfur and phosphorous
initiators are not typically used to make polyalkylene glycols.
U.S. Pat. No. 4,302,343 sets forth oxidation stability data showing
that amine initiated polyalkylene glycols are not oxidatively
stable even when typical antioxidant packages are present. In an
embodiment, the present technology employs non-amine initiators.
Lubricating Composition
[0034] The C.sub.4 or greater polyalkylene glycol can be combined
with one or more oils of lubricating viscosity, including natural
and synthetic lubricating oils, and mixtures thereof, with or
without additives. The C.sub.4 or greater polyalkylene glycol can
be combined with both oils of lubricating viscosity and additives.
When combined with other additives, the C.sub.4 or greater
polyalkylene glycol can be used in an amount sufficient to achieve
the desired electrical conductivity in the lubricating composition,
such as, for example from about 1 wt. % or greater of the total
weight of the lubricating composition, that is, from about 1 wt. %
to about 100 wt. %. In an embodiment, the C.sub.4 or greater
polyalkylene glycol can be employed in the lubricating composition
from about 0.01 to about 10 wt %, or from about 0.1 to about 8 or 9
wt. %, or from about 0.5 or 1 to about 6 or 7 wt. %. In an
embodiment, the C.sub.4 or greater polyalkylene glycol can be
employed in the lubricating composition from about 5 wt. % to about
25 wt. %, or from about 6 wt. % to about 20 wt. %, or alternatively
from about 7 to about 15 wt. %. One of ordinary skill in the art
can readily formulate the C.sub.4 or greater polyalkylene glycol
into a lubricating composition to balancing the desired
conductivity with the costs.
[0035] The oil of lubricating viscosity refers to an oil that
provides lubrication to moving parts. Desirably the lubricant will
be an aliphatic or cycloaliphatic oil with less than 10, more
desirably less than 5 and preferably less than 1 weight percent of
aryl and alkaryl molecules. Aryl and alkaryl molecules will be
defined to be compounds having one or more aromatic rings, either
as individual rings or as fused rings such as benzene, substituted
benzenes, naphthalene, substituted naphthalenes, anthracene etc.
Desirably these lubricants would have less than 10, more desirably
less than 5 mole percent, and preferably less than 1 mole percent
of compounds with unsaturated carbon to carbon double bonds, i.e.
they would be relatively free of unsaturation. They can
specifically include mineral oils with less than the specified
amounts of aryl and alkaryl compounds, hydrotreated mineral oils
with less than the specified amounts of aryl and alkaryls,
hydrocracked mineral oils, and polyalphaolefins. Desirably these
aliphatic or cycloaliphatic lubricants would have viscosities at 40
.degree. C. of from about 5 or 20 to about 200 cSt and preferably
from about 5 or 20 to about 100 or 150 cSt. These aliphatic oils
have better thermal and chemical stability than oils having higher
concentrations of unsaturation and/or aryl groups.
[0036] Suitable mineral oils that can be used in conjunction with
the C.sub.4 or greater polyalkylene glycol include those having a
viscosity range from about 20 to about 100 cSt at 40.degree. C.,
preferably from about 30 cSt to about 80 cSt at 40.degree. C. Such
oils are refined from crude oil of any source. Standard refinery
operations may be used in processing the mineral oil. Among the
general types of petroleum oils useful in the compositions of this
invention are solvent neutrals, bright stocks, cylinder stocks,
residual oils, hydrocracked basestocks, and paraffin oils including
pale oils. Such oils and blends of them are produced by a number of
conventional techniques which are widely known by those skilled in
the art.
[0037] Suitable synthetic lubricating oils include hydrocarbon oils
and halo-substituted hydrocarbon oils such as polymerized and
interpolymerized olefins [e.g., hydrogenated polybutylenes,
hydrogenated polypropylenes, hydrogenated propylene-isobutylene
copolymers, chlorinated hydrogenated polybutylenes, hydrogenated
poly(1-hexenes), hydrogenated poly(1-octenes), hydrogenated
poly(1-decenes)]; alkylbenzenes [e.g., dodecylbenzenes,
tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl) benzenes];
polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls);
and alkylated diphenyl ethers and alkylated diphenyl sulfides and
the derivatives, analogs and homologs thereof.
[0038] The term polyalphaolefins (PAO) is used to define the
polymers derived from polymerizing alpha olefin monomers and these
polymers are conventionally used as oils of lubricating viscosity
and lubricant additives. The polyalphaolefin has similar saturated
chains with good thermal stability to the aliphatic mineral oils
low in unsaturation. These polyolefins are polymers from olefins
having unsaturation between their alpha and beta carbon atoms
before the polymerization reaction. The polymerization and any
subsequent treatments (hydrogenation) convert the unsaturated
carbons to saturated carbons. The use of enough olefins of
sufficient length and the polymerization process provides many
alkyl branches of 2 to 20 carbon atoms that prevent crystallization
of the polyolefins when used as lubricants. Polyalphaolefin is not
used in this application to describe polymeric polyolefins that are
solids at room temperature and are used as plastics.
[0039] Polyalkylene glycols, other than the C.sub.4 or greater
polyalkylene glycol, that are useful as oils of lubricating
viscosity include alkylene oxide polymers and interpolymers and
derivatives thereof where the terminal hydroxyl groups have been
modified by esterification, etherification. These constitute
another class of known synthetic lubricating oils. These are
exemplified by polyoxyalkylene polymers prepared by polymerization
of ethylene oxide (POE) or propylene oxide (PPO), the alkyl and
aryl ethers of these polyoxyalkylene polymers (e.g.,
methyl-polyisopropylene glycol ether having an average molecular
weight of 1000, diphenyl ether of polyethylene glycol having a
molecular weight of 500-1000, diethyl ether of polypropylene glycol
having a molecular weight of 1000-1500); and mono- and
polycarboxylic esters thereof, for example, the acetic acid esters,
mixed C.sub.3-C.sub.8 fatty acid esters and C.sub.13 Oxo acid
diester of tetraethylene glycol.
[0040] Another suitable class of synthetic lubricating oils
comprises the esters of dicarboxylic acids (e.g., phthalic acid,
succinic acid, alkyl succinic acids and hydrogenated alkenyl
succinic acids, maleic acid, azelaic acid, suberic acid, sebacic
acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid,
alkylmalonic acids) with a variety of alcohols (e.g., butyl
alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol,
ethylene glycol, diethylene glycol monoether, propylene glycol).
Specific examples of these esters include dibutyl adipate,
di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate,
diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl
phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic
acid dimer, and the complex ester formed by reacting one mole of
sebacic acid with two moles of tetraethylene glycol and two moles
of 2-ethylhexanoic acid.
[0041] Esters useful as synthetic oils also include those made from
C.sub.5 to C.sub.12 monocarboxylic acids and polyols and polyol
ethers such as neopentyl glycol, trimethylolpropane,
pentaerythritol, dipentaerythritol and tripentaerythritol.
[0042] Silicon-based oils such as the polyalkyl-, polyaryl-,
polyalkoxy-, or polyaryloxysiloxane oils and silicate oils comprise
another useful class of synthetic lubricants; they include
tetraethyl silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl)
silicate, tetra-(4-methyl-2-ethylhexyl) silicate,
tetra-(p-tert-butylphenyl) silicate,
hexa-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxanes and
poly(methyl-phenyl) siloxanes. Other synthetic lubricating oils
include liquid esters of phosphorus-containing acids (e.g.,
tricresyl phosphate, trioctyl phosphate, diethyl ester of
decylphosphonic acid) and polymeric tetrahydrofurans.
[0043] Typical vegetable oils that may be used as base oils or as
components of the base oils include castor oil, olive oil, peanut
oil, rapeseed oil, corn oil, sesame oil, cottonseed oil, soybean
oil, sunflower oil, safflower oil, hemp oil, linseed oil, tung oil,
oiticica oil, jojoba oil, meadowfoam oil, and the like. Such oils
may be partially or fully hydrogenated, if desired.
[0044] The fact that the base oils used in the lubricant
compositions may be composed of (i) one or more mineral oils, (ii)
one or more synthetic oils, (iii) one or more vegetable oils, or
(iv) a blend of (i) and (ii), or (i) and (iii), or (ii) and (iii),
or (i), (ii) and (iii) does not mean that these various types of
oils are necessarily equivalents of each other. Certain types of
base oils may be used in certain compositions for the specific
properties they possess such as biodegradability, high temperature
stability, non-flammability or lack of corrosivity towards specific
metals (e.g. silver or cadmium). In other compositions, other types
of base oils may be preferred for reasons of availability or low
cost. Thus, the skilled artisan will recognize that while the
various types of base oils discussed above may be used in the
compositions of this invention, they are not necessarily functional
equivalents of each other in every instance. Oils of lubricating
viscosity that cannot be used are those that are not miscible with
one another.
Additives
[0045] Effective amounts of additives that can be employed in and
with the lubricant compositions can include, for example,
antioxidants, rust and corrosion inhibitors, metal deactivators,
lubricity additives, antiwear additives, or such additives as may
be required. Commercially available examples of antiwear additives
are additives such as tricresyl phosphate (TCP) available at
Syn-O-Add, 8484.RTM. available at Akzo-Nobel, or triphenyl
phosphorothionate (TPPT) available at Ciba Geigy. In general, the
lubricant composition will contain the additive components in minor
amounts sufficient to improve the performance characteristics and
properties of the oil of lubricating viscosity or basestock blend,
or to both the base oil and basestock blend. The amounts of the
respective components may vary in accordance with such factors as
the type and characteristics of the base oil or basestock blend
employed, the type and severity of the service conditions for which
the finished product is intended, for example, for use in a
positive displacement compressor, such as a rotary screw
compressor, a reciprocating rotary vane, or scroll, and the
specific performance properties desired in the finished product. In
an embodiment, the lubricating composition does not contain
naphthol.
[0046] Generally, additives used for their known purpose can
comprise from about 10% to about 0.01% by weight of the total
weight of the lubricant composition, and preferably from about 5%
to about .001% by weight based on the total weight of the
lubricating composition.
[0047] Examples of useful antioxidants include phenyl naphthyl
amines (alpha and/or beta), diphenyl amines, including alkylated
diphenyl amines. Commercially available examples of such
antioxidants are Irganox L-57.RTM. available at Ciba Geigy, and
Vanlube 81.RTM. available at Vanderbilt Chemical. Suitable
antioxidants are also exemplified by phenolic antioxidants,
aromatic amine antioxidants, sulfurized phenolic antioxidants, and
organic phosphites, among others. Examples of the phenolic
antioxidants include 2,6-di-tert-butylphenol, liquid mixtures of
tertiary butylated phenols, 2,6-di-tert-butyl-4-methylphenol,
4,4'-methylenebis(2,6-di-tert-butylphenol),
2,2'-methylenebis(4-methyl-6-tert-butyl-phenol), mixed
methylene-bridged polyalkyl phenols, and
4,4'-thiobis(2-methyl-6-tert-butylphenol).
N,N'-Di-see-butyl-p-phenylenediamine, 4-isopropylaminodiphenyl
amine, phenyl-alpha-naphthyl mine, phenyl-beta-naphthyl amine, and
ring-alkylated diphenylamines serve as examples of aromatic amine
antioxidants. Commercially available antioxidants useful for the
present invention also include Ethanox.RTM. 702 available at the
Ethyl Corporation, Irganox.RTM. L-135 and Irganox.RTM. L-118,
Irganox L-06.RTM. available at Ciba Geigy, and RC-7130.RTM.
available at Rhein Chemie.
[0048] Examples of suitable rust and corrosion inhibitors are
neutral metal sulfonates such as calcium sulfonate, magnesium
sulfonate, sodium sulfonate, barium dinonylnaphthalene sulfonate,
and calcium petroleum sulfonate. Other types of rust or corrosion
inhibitors which may be used comprise monocarboxylic acids and
polycarboxylic acids. Examples of suitable monocarboxylic acids are
oleic acids, octanoic acid, decanoic acid and dodecanoic acid.
Suitable polycarboxylic acids include dimer and trimer acids such
as are produced from such acids as tall oil fatty acids, oleic
acid, and linoleic acid. Also useful are carboxylic acid based,
metal free materials, such as hydroxy alkyl carboxylic esters.
Another useful type of rust inhibitor for use in the practice of
this invention is comprised of the alkenyl succinic acid and
alkenyl succinic anhydride corrosion inhibitors such as, for
example, tetrapropenylsuccinic acid, tetrapropenylsuccinic
anhydride, tetradecenylsuccinic acid, tetradecenylsuccinic
anhydride, hexadecenylsuccinic acid, hexadecenylsuccinic anhydride,
and the like. Also useful are the half esters of alkenyl succinic
acids having about 8 to about 24 carbon atoms in the alkenyl group
with alcohols such as the polyglycols. Other suitable rust or
corrosion inhibitors include ether amines; acid phosphates; amines;
polyethoxylated compounds such as ethoxylated amines, ethoxylated
phenols, and ethoxylated alcohols; imidazolines; and aminosuccinic
acids or derivatives thereof. Mixtures of such rust or corrosion
inhibitors can be used. U.S. Pat. No. 5,773,393 is incorporated in
its entirety herein for its disclosure regarding rust and corrosion
inhibitor additives. A commercially available example of a
corrosion inhibitor is L-859.RTM. available at the Lubrizol
Corporation.
[0049] Examples of suitable metal deactivators are complex organic
nitrogen, oxygen and sulfur-containing compounds. For copper,
compounds such as substituted benzotriazole, alkyl or acyl
substituted 5,5'-methylene-bis-benzotriazole, alkyl or acyl
substituted 2,5-dimercaptothiazole, salts of salicylaminoguanidine,
and quini- zarin are useful. Propylgallate is an example of a metal
deactivator for magnesium, and sebacic acid is an example of a
deactivator for lead. A commercially available example of a
triazole metal deactivator is Irgamet 39.RTM. available at Ciba
Geigy.
[0050] An effective amount of the foregoing additives is generally
in the range from about 0.005% to about 5% by weight of the total
weight of the lubricant composition for the antioxidants, from
about 0.005% to about 0.5% percent by weight based on the total
weight of the lubricant composition for the corrosion inhibitors,
and from about 0.001% to about 0.5% percent by weight of the total
weight of the lubricant composition for the metal deactivators. It
is to be understood that more or less of the additives may be used
depending upon the circumstances for which the lubricant
compositions are to be used.
[0051] In one embodiment, the lubricating composition comprises,
consists essentially of, or consists of a blend of (A) at least one
C.sub.4 or greater polyalkylene glycol, as described above, and (B)
at least one C.sub.1 to C.sub.3 polyalkylene glycol, wherein
greater than 50%, or greater than 60% or 70%, or even greater than
80% or 90%, and in some instances 100% of the repeat units in said
at least one C.sub.1 to C.sub.3 polyalkylene glycol contains an
alkylene oxide derived moiety comprising at least one of a C.sub.1,
C.sub.2, or C.sub.3 alkyl group or combination thereof. The ratio
of the at least one C.sub.4 or greater polyalkylene glycol to the
at least one C.sub.1 to C.sub.3 polyalkylene glycol can be from
about 1:1 to about 10:1 by weight. In some embodiments the ratio
can be 1.5:1 to about 8:1, or from about 2:1 to 6:1, and in some
embodiments from about 2.5:1 to about 4:1.
[0052] In an embodiment, the lubricating composition can comprise,
consist of, or consist essentially of at least one C.sub.4 or
greater polyalkylene glycol along with polymerized and/or
interpolymerized olefin base oils, such as, for example, a poly
alphaolefin ("PAO"). In an embodiment, the lubricating composition
can comprise, consist of, or consist essentially of at least one
C.sub.4 or greater polyalkylene glycol along with an ester base
oil, such as, for example, esters of dicarboxylic acids, esters
made from C.sub.5 to C.sub.12 monocarboxylic acids and polyols and
polyol ethers, and/or vegetable oil esters. In a further
embodiment, the lubricating composition can comprise, consist of,
or consist essentially of at least one C.sub.4 or greater
polyalkylene glycol along with a mineral oil base oil.
[0053] In an embodiment, the lubricating composition can comprise,
consist of, or consist essentially of at least one C.sub.4 or
greater polyalkylene glycol from about 0.01 to about 10 wt. %, from
about 0.005 to about 5 wt. % of an antioxidant, and the balance of
a base oil. In an embodiment, the lubricating composition can
comprise, consist of, or consist essentially of at least one
C.sub.4 or greater polyalkylene glycol from about 5 to about 25 wt.
%, from about 0.005 to about 5 wt. % of an antioxidant, and the
balance of a base oil.
[0054] In another embodiment, the lubricating composition can
comprise, consist of, or consist essentially of at least one
C.sub.4 or greater polyalkylene glycol from about 0.01 to about 10
wt. %, from about 0.005 to about 0.5 wt. % of a corrosion
inhibitor, and the balance of a base oil. In another embodiment,
the lubricating composition can comprise, consist of, or consist
essentially of at least one C.sub.4 or greater polyalkylene glycol
from about 5 to about 25 wt. %, from about 0.005 to about 0.5 wt. %
of a corrosion inhibitor, and the balance of a base oil.
[0055] In another embodiment, the lubricating composition can
comprise, consist of, or consist essentially of at least one
C.sub.4 or greater polyalkylene glycol from about 0.01 to about 10
wt. %, from about 0.001 to about 0.5 wt. % of a metal deactivator,
and the balance of a base oil. In another embodiment, the
lubricating composition can comprise, consist of, or consist
essentially of at least one C.sub.4 or greater polyalkylene glycol
from about 5 to about 25 wt. %, from about 0.001 to about 0.5 wt. %
of a a metal deactivator, and the balance of a base oil.
[0056] In a further embodiment, the lubricating composition can
comprise, consist of, or consist essentially of at least one
C.sub.4 or greater polyalkylene glycol from about 0.01 to about 10
wt. %, or from about 5 to about 25 wt. %; along with an additive
package comprising, consisting essentially of, or consisting of
from about 0.005 to about 5 wt. % of an antioxidant, from about
0.005 to about 0.5 wt. % of a corrosion inhibitor, and from about
0.001 to about 0.5 wt. % of a metal deactivators; and a base oil to
the balance of the lubricating composition.
[0057] The lubricating compositions, when used in a positive
displacement compressor, such as a reciprocating rotary vane, a
scroll, or a rotary screw air compressor, are selected so as to
have a viscosity in the range of about 10 to about 150 centistokes
at 40.degree. C., preferably from about 22 to about 100 centistokes
at 40.degree. C., and most preferably of about 32 to about 68
centistokes at 40.degree. C., and a pour point in the range of
about -10.degree. C. to about -100.degree. C., and preferably from
about -20 .degree. C. to about -70.degree. C., and in some
embodiments from about -10 .degree. C. to about -40 .degree. C. or
-60 .degree. C.
[0058] The technology also is directed to a process of lubricating
a piece of equipment, for example, a positive displacement
compressor such as a reciprocating rotary vane, a scroll, or a
rotary screw air compressor.
[0059] The technology additionally includes a method of operating a
piece of equipment, for example, a positive displacement compressor
such as a reciprocating rotary vane, a scroll, or a rotary screw
air compressor. The method can include lubricating the piece of
equipment with a lubricant composition as herein disclosed, and
operating the piece of equipment. A compressor operated with the
lubricant composition herein disclosed will have a lower
electro-static charge build-up during operation than a compressor
operating without the lubricant composition.
[0060] The lubricant compositions are useful as thermally and
oxidatively stable compressor lubricants that can maintain the
conductivity of the lubricant when heated, particularly when heated
for extended periods, such as, for example, for about 8 hours or
more. In an embodiment, the lubricant compositions can increase the
conductivity to greater than 50 Ps/m at room temperature (i.e.,
25.degree. C.).
[0061] The lubricant compositions are also useful to reduce or
prevent the buildup of static charge in a compressor, such as a
reciprocating rotary vane, scroll, rotary screw air, centrifugal,
or axial compressor. The lubricants can be used alone as a
lubricant, or they can be combined with effective amounts of
additives useful in compressors. In an embodiment, the C.sub.4 or
greater polyalkylene glycol can be employed to prevent
electrostatically ignited fires in a compressor lubricant, wherein
greater than 50% of the repeating units in said at least one
C.sub.4 or greater polyalkylene glycol contain a C.sub.4 or greater
alkylene oxide moiety.
[0062] A compressor operated according to the present invention
runs at a discharge operating temperature range of from about
150.degree. F. to about 250.degree. F. or 300.degree. F. (about
65.degree. C. to about 120.degree. C. or 150.degree. C.). The
compressor can run as much as 24 hrs/day, seven days/wk, for many
years. In the most extreme case, shutdown will occur only for
maintenance.
[0063] The lubricant compositions are useful in compressor
oils.
[0064] The amount of each chemical component described is presented
exclusive of any solvent or diluent oil, which may be customarily
present in the commercial material, that is, on an active chemical
basis, unless otherwise indicated. However, unless otherwise
indicated, each chemical or composition referred to herein should
be interpreted as being a commercial grade material which may
contain the isomers, by-products, derivatives, and other such
materials which are normally understood to be present in the
commercial grade.
[0065] It is known that some of the materials described above may
interact in the final formulation, so that the components of the
final formulation may be different from those that are initially
added. The products formed thereby, including the products formed
upon employing the composition of the present invention in its
intended use, may not be susceptible of easy description.
Nevertheless, all such modifications and reaction products are
included within the scope of the present invention; the present
invention encompasses the composition prepared by admixing the
components described above.
[0066] The invention herein is useful, inter alia, for reducing the
electro-static charge build-up in a positive displacement
compressor, which may be better understood with reference to the
following examples.
EXAMPLES
Example 1
[0067] The electrical conductivity results of air compressor
lubricant compositions are shown in Tables 1 and 2. All
formulations were combinations of the base oils listed with and
without anti-static additives. All formulations described contained
a standard commercial additive package providing antioxidancy,
corrosion inhibition and foam control to the finished air
compressor fluid. Anti-stat#1 is a mixture of kerosene, o-xylene,
dodecylbenzene sulfonic acid, heavy aromatic naptha, and other
chemicals, available from Innospec.TM. under the trade name
STADIS.TM. 425. Antistat#2 is a mixture of polyalkylene glycols
containing C.sub.4 or greater polyalkylene glycols, available from
Dow.TM. as OSP46.TM..
[0068] Results show the raising of electrical conductivity as
desired with the use of both additives in various base oil types
and combinations.
TABLE-US-00001 TABLE 1 Electrical Formulation Anti-Stat
Conductivity Number Base Oil Composition Additive (pS/m) 1 90% PAO
10% Diester None <1 2 70% PAO 30% POE None 3 3 60% PAO 40% POE
None 19 4 40% PAO 60% POE None 24 5 100% POE None 33 6 70% PAO 30%
POE 10 ppm #1 13 7 70% PAO 30% POE 50 ppm #1 252 8 70% PAO 30% POE
100 ppm #1 843 9 40% PAO 60% POE 100 ppm #1 525 10 40% PAO 60% POE
500 ppm #1 1950 11 100% PAO 10% #2 20 12 100% PAO 30% #2 116 13
100% PAO 54% #2 765 14 100% POE 66% #2 2510 15 None 100% #2
1235
[0069] Samples of the select air compressor fluids from Table 1
were then heated in an oven to 91.degree. C., and then allowed to
cool to 23.degree. C. After cooling, the samples were tested for
electrical conductivity according to ASTM D2624. Results of the
tests are shown in Table 2 below. This is to study the effect of
fluid usage on electrical conductivity and is intended to simulate
conductivity stability of the fluid in use in a working air
compressor.
TABLE-US-00002 TABLE 2 Formulation Electrical Conductivity Number
Heat Cycles (pS/m) 2 0 f5 1 8 2 5 7 0 252 1 200 2 125 13 0 759 1
770 15 0 1235 1 1525 2 1701
[0070] The results show that operating an air compressor on the
lubricant composition disclosed herein containing a C.sub.4 or
greater polyalkylene glycol will increase the electrical
conductivity of the lubricant, thereby reducing the electro-static
build-up of charge within the air compressor and reducing the risk
of fire hazards in a working compressor. The results also show that
known anti-stat additives lose their efficacy as the fluid is used
and heated in a working compressor.
[0071] Each of the documents referred to above is incorporated
herein by reference, including any prior applications, whether or
not specifically listed above, from which priority is claimed. The
mention of any document is not an admission that such document
qualifies as prior art or constitutes the general knowledge of the
skilled person in any jurisdiction. Except in the Examples, or
where otherwise explicitly indicated, all numerical quantities in
this description specifying amounts of materials, reaction
conditions, molecular weights, number of carbon atoms, and the
like, are to be understood as modified by the word "about." It is
to be understood that the upper and lower amount, range, and ratio
limits set forth herein may be independently combined. Similarly,
the ranges and amounts for each element of the invention can be
used together with ranges or amounts for any of the other
elements.
[0072] As used herein, the transitional term "comprising," which is
synonymous with "including," "containing," or "characterized by,"
is inclusive or open-ended and does not exclude additional,
un-recited elements or method steps. However, in each recitation of
"comprising" herein, it is intended that the term also encompass,
as alternative embodiments, the phrases "consisting essentially of"
and "consisting of," where "consisting of" excludes any element or
step not specified and "consisting essentially of" permits the
inclusion of additional un-recited elements or steps that do not
materially affect the essential or basic and novel characteristics
of the composition or method under consideration.
[0073] While certain representative embodiments and details have
been shown for the purpose of illustrating the subject invention,
it will be apparent to those skilled in this art that various
changes and modifications can be made therein without departing
from the scope of the subject invention. In this regard, the scope
of the invention is to be limited only by the following claims.
* * * * *