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An important factor in determining the useful life of a lubricant is the
presence of contaminants which affect the life and efficiency of the
device being lubricated as well as the life of the lubricant. Lubricating
oils are called upon to reduce friction, carry away heat, protect against
rust, protect against wear, and seal out contaminants and their properties
are adversely affected by contamination.
The effects of some of the contaminants referred to briefly are as follows:
1. Water in even small amounts promotes rusting of iron or steel and helps
to form water sludges (emulsions) which may clog oil passages, pumps,
valves, and other oil-handling equipment. Water contributes to the
deterioration of lubricants and uses up any demulsifier additives which
may have been incorporated. It may also contribute to foaming problems.
2. Solid abrasive particles of dirt, dust, grit, and metallic fragments
circulated by the lubricant obviously have a detrimental effect. Excessive
wear, scoring of bearing surfaces, and possible failure due to seizing or
metal fatique are commonly the result of this type of contamination.
Smaller particles may even become embedded in the soft bearings surfaces,
such as engine bearings, and act as a sort of lapping or grinding
compound, which action is cumulative and thus greatly accelerates wear.
Larger particles score bearing surfaces, which would lead to eventual
bearing failure by seizing or fatigue.
3. Sludge, which is a combination of water, dirt, and oil deterioration,
produces deposits in the lowest parts of the oil system and clogs small
oil passages, clearances, and ultimately filters. When sludge is subject
to the influence of heat, it will form a hard, gummy substance, usually
called lacquer or varnish. This type of sludge causes sticking of valves,
mitigates against the continuous operation of oil pumps, and can, of
course, seriously interfere with the oil circulation.
4. Liquid contamination, such as unburned fuel from engines, will dilute
lubricating oils and possibly reduce their viscosity beyond a safe
load-carrying capacity. Conversely, contamination of the lubricant with a
heavier oil increases viscosity and interfers with the oil circulation,
thereby affecting its lubricating value and heat-transfer capacity.
When the contaminants become too great, the lubricant generally is
discarded.
In recent years because of the high price of oil and more stringent
anti-pollutio;n standards, there has been increasing interest in
reclaiming lubricants for reuse.
We have now discovered that contaminated lubricating oils (i.e., spent lube
oil) which usually are discarded can be reclaimed for reuse by a process
which comprises:
Treating the lubricant with a surfactant in combination with an amine, more
particularly an anionic surfactant in combination with a polyalkylene
polyamine. In practice we prefer to employ a salt of an anionic surfactant
in combination with polyalkylene amine such as those of the formula
##STR1##
and where n is an integer such as about 1-12, for example 1-8, such as
about 1-5, but preferably about 2-3; A is alkylene such as
(CH.sub.2).sub.m where m is about 2-10, such as about 2-8, but preferably
about 2-6.
In carrying out the process, the treating agent is added to the spent
lubricant reduced in viscosity, preferably by heating to an elevated
temperature, such as about 50.degree. to 200.degree. C., for example from
about 90.degree. to 110.degree. C., but preferably from about 80.degree.
to 150.degree. C. One method of stirring is to bubble air through the
lubricant. Sometimes because of convection currents in the oil it may be
difficult for the treated oil to settle very effectively. One means of
achieving good settling is to impose super-atmospheric pressure on the
vessel. This is conveniently done by closing in the reaction vessel before
heating, the vapors evolving on heating being sufficient to impose
sufficient super-atmospheric pressure on the system so as to reduce
convection currents in the oil which inhibit good settling. Separation of
the impurities is achieved by any suitable means such as by gravity,
filtration, centrifigations, etc. and combinations thereof.
The surfactant employed herein is preferably anionic, either employed as is
or as a salt thereof. The following outlines types of anionic surfactants
which can be employed herein.
ANIONIC SURFACTANT
A. carboxylic acids:
1. Carboxyl joined directly to the hydrophobic group (subclassification on
basis of the hydrophobic group), e.g., fatty acids, soaps, rosin soaps,
etc.
2. Carboxyl joined through an intermediate linkage.
a. Amide group as intermediate link.
b. Ester group as intermediate link.
c. Sulfonamide group as intermediate link.
d. Miscellaneous intermediate links, ether, --SO.sub.2 --, --S--, etc.
B. sulfuric esters (sulfates):
1. Sulfate joined directly to hydrophobic group.
a. Hydrophobic group contains no other polar structures (sulfated alcohol
and sulfated olefin type).
b. Sulfuric esters with hydrophobic groups containing other polar
structures (sulfated oil type).
2. Sulfate group joined through intermediate linkage.
a. Ester linkage (artic Syntex M. type).
b. Amide linkage (Xynomine type).
c. Ether linkage (Triton 770 type).
d. Miscellaneous linkages (e.g., oxyalkylamidazole sulfates).
C. alkane sulfonic acids:
1. Sulfonic group directly linked
a. Hydrophobic group bears other polar substituents ("highly sulfated oil"
type). Chloro, hydroxy, acetoxy, and olefin sulfonic acids (Nytron type).
b. Unsubstituted alkane sulfonic acids (MP 189 type; also cetane sulfo acid
type).
c. Miscellaneous sulfonic acids of uncertain structure, e.g., oxidation
products of sulfurized olefins, sulfonated rosin, etc.
2. Sulfonic groups joined through intermediate linkage.
a. Ester linkage.
1. RCOO X--SO.sub.3 H (Igepon AP type).
2. ROOC--X--SO.sub.3 H (Aerosol and sulfo-acetate type).
b. Amide linkage.
1. RCONH--X--SO.sub.2 H (Igepon T type).
2. RNHOC--X--SO.sub.3 H (sulfosuccinamide type).
c. Ether linkage (Triton 720 type).
d. Miscellaneous linkages and two or more linkages.
D. alkyl aromatic sulfonic acids:
1. Hydrophobic group joined directly to sulfonated aromatic nucleus
(subclasses on basis of nature of hydrophobic group. Alkyl phenols,
terpene, and rosin-aromatic condensates, alkyl aromatic ketones, etc.).
2. Hydrophobic group joined to sulfonated aromatic nucleus through an
intermedite linkage.
a. Ester linkage (sulfophthalates, sulfobenzoates).
b. Amide and imide linkages.
1. R--CONH--ArSO.sub.3 H type.
2. Sulfobenzamide type.
c. Ether linkage (alkyl phenyl ether type).
d. Heterocyclic linkage (Ultravon type, etc.).
e. Miscellaneous and two or more links.
E. miscellaneous anionic hydrophilic groups:
1. Phosphates and phosphonic acids.
2. Persulfates, thiosulfates, etc.
3. Sulfonamides.
4. Sulfamic acids, etc.
The following are specific examples of representative surfactants: (1)
Oxyalkylated alcohols or phenols terminally reacted with sulfamic acid,
for example, R(OA).sub.n OH + sulfamic acid where R is alkyl, aryl, etc.
A typical alcohol is Alfol 8-10 which is a straight chain alcohol having
between 8-10 carbons. Reaction with sulfamic acid converts the terminal OH
group to the ammonium salt of a sulfate ester. A typical phenol is an
oxyalkylated nonyl phenol reacted with sulfamic acid.
Other specific examples are: (1) The disodium salt of sulfonsuccinic acid
derived from a C.sub.10 -C.sub.12 straight chain oxyethylated alcohol.
2. The disodium salt of the half-ester of sulfosuccinic acid derived from a
C.sub.10 -C.sub.12 straight chain oxyethylated alcohol mixture;
3. Disodium salt of sulfosuccinic acid derived from oxyethylated nonyl
phenol;
4. Dodecyl benzene sulfonic acid neutralized with ammonia.
A wide variety of polyamines can be employed. Typical polyamines are
polyalkylene polyamines, for example, of the formula
##STR2##
as defined above where A is alkylene-straight chain or branched, for
example of the formula
##STR3##
where n=1-10 or more
m=2-10 or more.
Typical examples include
##STR4##
where n=1-5 or higher, including mixtures thereof.
##STR5##
where n=1-5 or higher or mixtures thereof.
##STR6##
n=1-5 or higher or mixtures thereof.
##STR7##
n=1-5 or higher or mixtures thereof, etc.
The weight ratio of surfactant to amine will vary depending on many factors
such as a weight ratio of 95 to 5 to 5 to 95, such as about 20 to 70, for
example, about 70 to 20, but preferably from about 60 to 40.
The amount of treating agent employed will vary widely depending on many
factors, from about 0.01% to 5.0% by weight of the oil to be treated, such
as from about 0.05 to 4.0%, for example, from about 0.5T to 3.0%, but
preferably from about 0.1 to 2.0%. Larger amounts can be employed but
generally there is no economical advantage in so doing.
The following are typical treating agents:
EXAMPLE A
______________________________________
Weight % based on
Component Weight % Active Ingredients
______________________________________
Water 52.52
Dodecylbenzene sulfonic
acid, ammonium salt
29.16 61.4
Mixed polyethylene
polyamines* 18.32 38.6
##STR8##
______________________________________
*56% DET n=2
29% TET n=3
7% TEP n=4
5% PEH n=5
3% higher n=>5
EXAMPLE B
The composition of Example A except that
##STR9##
is employed in place of the mixed polyalkylene polyamines,
EXAMPLE C
The composition of Example A except the ethylene diamine is employed in
place of the mixed polyethylene polyamines.
The following non-limiting examples are presented to illustrate our
treating procedures.
Example 1
Spent lube oil was mixed with 0.4% by weight of treating agent based on
lube oil and heated to about 95.degree.-100.degree. C. Then the hot
treated mixture was centrifuged in a De Luval centrifuge to yield reusable
lube oil.
Example 2
Spent lube oil heated to about 115.degree.-120.degree. C. was pumped to a
treater to which 2% by weight of treating agent based on lube oil was
added. The treater was sealed and placed under a slight super atmosphere
by air added at 20 psi (which added to the pressure carried by evolved
vapors) for a period of about 2 hours to yield a reusable lube oil.
Example 3
Spent lube oil containing 1% by weight of treating agent based on lube oil
was circulated for about 1 hour in a heater at about 80.degree.-85.degree.
C. Thereupon it was pumped into a treater which was open to the
atmosphere. After a treating period of about 4 hours, reusable lube oil
was obtained.
All of the above examples were operable with each of the treating agents of
Examples A, B or C.
The reclaimed lube oil was separated from the water and other impurities
that settled to the bottom of the treating vessel.
The specific examples set forth above are not intended to limit the
invention solely thereto, but to include all variations and modifications
within the spirit of this invention.
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