Note: Descriptions are shown in the official language in which they were submitted.
~ ~ 1 V ~ 7 3 ~ ~
OVERBASED PHENATE PROCESS
8ackground of the Invention
1. Field of the Invention
The present invention relates generally to processes
for manufacturing overbased sulfurized alkaline earth
metal alkylphenateq in which an alkaline earth metal base,
sulfur, and an alkylphenol are first reacted in the pres-
ence of a mutual solvent to form a sulfurized metal phen-
ate intermediate, following which the intermediate is
overbased via carbonation in the presence of additional
alkaline earth metal base. In particular, the invention
concerns a batch process in which throughput is substan-
tially increased by conducting the carbonation step in a
single stage in which CO2 is introduced to the reaction
vessel concurrently with the introduction of alkaline
earth metal base at a prescribed mole ratio of CO2 to
metal base.
2. Discussion of aackground Art
Lubricating oils tend to deteriorate under normal
conditions encounteced in present day diesel and automo-
tive engines. Sludge, lacquer and resinous materials can
form and adhere to engine parts, especially piston rings,
grooves and skirts which can have a harmful effect on
25 engine efficiency, operation and useful life. Commonly, -
additives are incorporated in lubricating oils to reduce
the formation of such materials or to keep them suspended
so that engine partq are kept clean and operating prop-
erly~ Additives which reduce the tendency of lubricating
oils to form oxidation products are called antioxidants,
while additives which tend to suspend oxidation products
and sludges, or cleanse the engine parts of such products,
are called detergents or dispersants. It is not uncommon ~-
for certain additives to exhibit both antioxidant and det-
ergency properties.
Overbased sulfurized alkaline earth metal alkylphen-
ates have been found to be especially useful for the dual
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purpose of providing oxidation inhibition and detergency
in a lubricating oil.
The term "overbased" refers to the fact that the
phenate material incorporates a large excess of alkalinQ
earth metal base over that necessary to neutralize the
phenate. Typically, an overbased phenate will have a TBN
(total base number) of about 100-400. Such high basicity,
which enables the additive to neutralize harmful acids
formed in engine combustion, is accomplished using a well
known technique usually referred to as carbonation or car-
bonate overbasing. This technique generally involves for-
mation of an initial alkaline earth metal sulfurized
phenate intermediate having relatively low levels of metal :~
base. This intermediate is then treated with a large
excess of additional alkaline earth metal. In a reaction
that is not well understood, the sulfurized metal phenate
intermediate is reacted with the excess metal base in a ~ -
suitable solvent, usually a glycol, by subjecting the
reactants to blowing with gaseous carbon dioxide. The CO2
treatment, or carbonation, results in the formation of a
fine colloidal dispersion whereby the excess metal base is
essentially "dissolved."
It is well known in the art to carry out the manufac-
ture of overbased sulfurized alkaline earth metal alkyl-
phenates ineithera batch process or a continuous process.
There are significant advantages and disadvantages attend-
ant to both types of processing.
~or example, batch processing has the major disadvan-
tage that, as would be expected, much less product can bemanufactured over a given period of time than would be the
case if one used a continuous proc~;s. Nevertheless, a
very significant advantage in batch processing is that the
degree or extent of carbonation can be very closely and
reliably controlled. This is important because overcarbo-
nating or undercarbonating the overbased phenate can
result in serious problems. Overcarbonated product gener-
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ally shows poor water tolerance in lubricant formulations
and is hazy due to break up of the colloidal dispersion
mentioned above. Undercarbonated product tends to have
S increased viscosity, poor filterability, and resists
glycol stripping. aatch processing avoids these problems
and, in particular, is the method o choice if a water
tolerant phenate is a critlcal objective.
Continuous processing has the advantage of maximizing
lo production throughput. However, in continuous processes
- typically a first reactor is used to carry out formation
of the initial sulfurized metal phenate intermediate while
a second reactor or a series of successive reactors are
used for carbonation. A well-known phenomenon associated
lS with continuous processes is that of residence time dis-
tribution. This phenomenon is particularly detrimental in
the carbonation step of continuous phenate processes
because it results in the formation of both overcarbonated
and undercarbonated phenate. For this reason, overbased
phenates prepared in continuous processes generally
elicit significantly poorer water tolerance than batch
prepared phenates. The residence time distribution phe-
nomenon can be minimized by increasing the number of reac-
tors used for the carbonation step to approximate a plug
flow reactor, but not without substantial capital outlay.
Ideally, it is desired to have the best of both ~ -
worlds--the production throughput of continuous process-
ing, with the control over carbonation afforded by batch ~-~
processing, to ensure a phenate having excellent water
tolerance properties.
There are numerous patents directed to the manufac-
ture of overbased sulfurized alkaline earth metal alkyl-
phenates. ~3elgium Patent No. 876,119, thought to be the
most pertinent, discloses a process for manufacturing a
sulfurized overbased alkaline earth metal alkylphenate in
which formation of a sulfurized metal phenate intermediate
is achieved by contacting a Group II metal base, alkylphe-
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nol, and a mutual solvent in a heat exchanger for a timesufficient to form a metal phenate and then passing the
phenate without substantial cooling into a reaction zone
where said metal phenate i~ contacted at reaction condi-
tions with sulfur to form the sulfurized metal phenate.
This intermediate can then undergo carbonation with CO2.
Although the patent refers to "semi batch" processes where
reactants are added to a reaction vessel while reaction is
occurring, the patent fails to teach or suggest the unique
measures adopted in the present invention with respect to
carbonation.
A general object of the present invention is to pro-
vide a batch process for preparing overbased metal phenate
having improved production throughout without at the same
time incurring the disadvantages associated with contin-
uous processing. Other objects will be apparent herein-
after to those skilled in the art.
Summarv of the Invention ~ :~
The present invention is a process for preparing an
overbased sulfurized alkaline earth metal alkylphenate
which comprises the steps of: (a) contacting at reaction
conditions in a reaction vessel a mixture comprising an
alkylphenol, sulfur, a promoter solvent, and an alkaline
earth metal base to form a sulfurized alkaline earth metal
alkylphenate: followed by (b) overbasing the sulfurized
alkaline earth metal alkylphenate formed in (a) above by
charging simultaneously to said reaction zone and reacting
therein under reaction conditions (i) alkaline earth metal
base (ii) promoter solvent and (iii) carbon dioxide at a
mole ratio of carbon dioxide to alkaline earth metal base
of about 0.40:1 to about .95:1 and at a controlled rate
not substantially greater or less than the rate at which
the carbon dioxide, alkaline earth metal base, and sulfur-
ized alkaline earth metal phenate undergo reaction; and
(c) upon completion of said charging of alkaline earth
7 ~3 ~
.
metal compound and promoter solvent to the reaction zone,
allowing said carbon dioxide charge to continue until com-
pletion o the reaction.
In a related embodiment the invention is eurther
directed to a process for preparing an overbased sulfur-
ized alkaline earth metal alkylphenate which comprises the
steps of: (a) passing a mixture consisting essentially of
alkaline earth metal base and alkylphenol in a mole ratio
of about 0.1:1 to about 1.0:1 through pre-heating means
into a reaction vessel such that said mixture enters the
reaction vessel pre-heated to a temperature Oe from about
280 to 380F; while simultaneously charging about 0.1 to ~ ::
about 1.0 moles Oe a promoter solvent per mole of alkyl-
phenol into the reaction vessel; followed by ~b) charging
into the reaction vessel about 1.0 to about 2.0 moles of ~ ~
sulfur per mole of alkylphenol over a period of about -:: -
20-180 minutes, while maintaining the reaction vessel at a
reaction temperature of about 280-380F; (c) upon com- ::
20 pletion Oe the suleur charge, allowing the contents of the :~
reaction vessel to interact at said reaction temperature . : :
- for a period Oe time sufficient to form a sulfurized alka-
line earth metal alkylphenate; (d) converting the sulfur- ~ ~ -
ized alkaline earth metal alkylphenate formed above to an -;;~
25 overbased phenate by charging simultaneously to said :~ ~ :
reaction vessel and reacting therein at a temperature of. : :
from about 280 to about 380F, (i) about 0.5 to 2.0 moles : ~:
alkaline earth metal base per mole of alkylphenol, :~
(ii) about 0.5 to 2.0 mole~ of promoter solvent per mole
30 Oe alkylphenol; and (iii) about .40 to about .95 moles of :~
carbon dioxide gas per mole of alkaline earth metal base,
at a controlled charge rate not substantially greater or -
less than ~he rate at which the reactants present in the -~
vessel undergo reaction to form the overbased phenate: and :~
~e) upon completion of said charging Oe alkaline earth
metal base and promoter solvent to the reaction vessel,
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allowing said carbon dioxide charge to continue until com-
pletion of the reactlon.
While the present inventLon may be considered a batch
process, the method of carbonation used in the process
significantly reduces the reaction cycle time so that the
process can approach or equal the production throughput of
a continuous process. A further reduction in reaction
cycle time can be achieved if, as required in the above
related embodiment, the sulfurization step utilizes a pre-
heating means to introduce the alkylphenol and metal base
into the reaction vessel at the temperature of reaction as
opposed to charging them at ambient temperature and wait-
ing for the reactor to heat up to the desired reaction
15 temperature. Overbased phenates prepared using the proc- `-
ess of the present invention elicit excellent water tol- ~ -
erance properties usually associated with batch processing
even though the process can reduce the reaction cycle time
of a typical 9 to 10 hour batch reaction by as much as 4
to 5 hours.
Detailed Description
Generally speaking, the process of the present
invention can be carried out in a single commercial ~ize
stirred tank reactor in two stages. In the first stage, a
sulfurized alkaline earth metal alkylphenate intermediate
is formed by contacting under reaction conditions a suit-
able alkylphenate, an alkaline earth metal base, and
sulfur in the presence of a promoter or mutual solvent.
In the second stage of the process (carbonation) the sul-
~urized metal phenate intermediate undergoes treatment
with CO2 gas in the presence of an additional amount of
alkaline earth metal base and promoter solvent. ~y
effecting certain modifications to one or both of these
stages, the present invention dramatically reduces the
reaction cycle time required to produce a furnished batch
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of overbased phenate product. Each Oe the two stages will
now be discussed in greater detail.
Formation of Sulfurized Metal
Phenate Intermediate
rn the front end of the process Oe the present
invention an alkylphenol, an alkaline earth metal base and ~
sulfur are reacted in the presence of a promoter solvent ~ -
to form a suleurized metal phenate.
The alkylphenols useful in the present invention are
of the formula R~C6~4)~H where R is a straight chain or
branched chain alkyl group having from 8 to 40 carbon ~ -~
atoms and preferably from 10 to 30 carbons, and the moiety
(C6H4~ is a benzene ring. Examples of suitable alkyl
groups are octyl, decyl, dodecyl, tetradecyl, hexadecyl,
etc.
The alkaline earth metal base can be a base Oe cal-
cium, barium, magnesium and strontium. Preferred are cal-
cium and magnesium. The most commonly used bases are theoxides and hydroxides Oe the above metals such as calcium
oxide, calcium hydroxide, barium oxide, barium hydroxide,
magnesium oxide, and the like. Calcium hydroxide, com- ;
monly called hydrated lime, is most commonly used in the
manufacture Oe sulfurized calcium phenates, and it is pre-
ferred to use hydrated lime of good quality (relatively
eree of carbonates) which haq not deteriorated during sto-
rage.
The promoter solvent, also sometimes referred to as a
mutual solvent, can be any stable organic liquid which has
appreciable solubility for both the alkaline earth metal
base, the alkylphenol, and the sulfurized metal phenate
intermediate. Although a wide variety of mutual solvents
are known in the art, many of such suitable solvents are ~ -
glycols and glycol monoethers such as ethylene glycol,
1,4-butane diol, derivatives of ethylene glycol, such as
monomethyl ether, monoethyl ether, etc. The vicinal gly-
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cols are preferred and ethylene glycol is most preferred
because it serves to activate the neutralization reaction
and to that extent typifies a catalyst, although the exact
characteristics describing its function are unknown.
The sulfur used in the reaction is elemental sulfur.
In the present invention it has been found desirable to
use molten sulfur.
It is further desirable, although not required, in -
the present invention to use as a promoter in formation of
- the sulfurized phenate a low base alkylbenzene sulfonate.
The sulfonates suitable for use are, e.g., the sulfonic
acid salts of molecular weight preferably of more than 400
obtained by sulfonating alkyl-benzenes derived from ole-
fins or polymers of C2 to C4 olefins of chain length
C15-C80 and alkaline earth metals such as calcium, barium,
magnesium etc. In the Examples following this discussion,
a low base calcium sulfonate prepared from a polypropene
of about C-60 chain length was included in the sulfuriza-
tion reaction.
In addition to the above reactants, formation of thesulfurized metal phenate is desirably carried out in the
presence of a lubricating oil reaction diluent. The
lubricating oil can be any lubricating oil that is used in
the final lubricating oil formulation containing the phen-
ate prepared by the present invention such as a 5W, lOW or
40W oil, including naphthenic base, paraffin base
and mixed based mineral oils. A 5W oil is generally moct
suitable as a reaction diluent.
The range of reaction stoichiometry for the above
reactants is as follows:
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Range Preferred Ranqe
Sulfur, mol/mol DDP* 1.0-2.0 1.3-1.6 ~ ~
5Ca(OH)2, mol/mol DDP 0.1-1.0 0.4-0.6 ---
Glycol, mol/mol DDP 0.1-1.0 0.4-0.6
*dodecylphenol
The amount of diluent oil is generally about 200 to
300 grams per mole of alkylphenol. The amount of low base
sulfonate (if used) is about 10-20 grams per mole of
alkylphenol.
The reaction to form the sulfurized alkaline earth -
15 metal alkylphenate is carried out in the present invention ~-
by contacting the alkaline earth metal base, the alkylphenate, -~
the promoter solvent, the lubricating oil diluent, and the ~ u
optional low base sulfonateiat a reaction temperature of
about 280 to about380F, preferably about 320 to about
20 360F for sufficient time to form the desired intermedi- ~ -
ate, normally about 40 to 80 minutes.
To avoid the time wasted while the reactor is being
raised to the desired reaction temperature of 280-330P,
the alkylphenol and alkaline earth metal base are prefera~
25 bly charged to the reactGr across a preheater set at the
desired reaction temperature while simultaneously the pro-
moter solvent is charged to the reaction vessel sepa- ~I
rately. It is preferred not to charge the glycol solvent
across the preheater with the Ca(OH)2 and alkylphenol
because the glycol will form a complex (calcium glycol
oxide) which will plug up the preheater, typically a heat
exchanger.
After the metal base, alkylphenol and promoter sol-
vent have been added, the sulfur is added to the reaction
3, mixture at a sufficiently slow rate to control the
reaction exotherm and off-gas evolution. Slow sulfur
addition (over a period of 30-60 minutes) is particularly
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important if the alkylphenate and metal base have been
charged to the reaction vessel preheated.
Carbonation
Following formation of the sulfurized metal phenate
intermediate as described above, carbonate ovPrbasing can
be achieved according to the pre~ent invention by adding
more alkaline earth metal base and promoter solvent to the
reaction vessel while ~imultaneouqly carbonating with CO2
gas. The range of reaction stoichiometry for the carbona-
tion is as follows:
RangePreferred Ranae
Ca(OH)2, mol/mol DDP* 0.5-2.0 1.0-1.5
Glycol, mol/mol DDP0.5-2.0 1.0-1.5
CO2, mol/~ol DDP 0.5-2.0 1.0-1.5
~Dodecylphenol
In accordance with the present invention, the alka-
line earth metal base, promoter solvent, and CO2 are
charged to the reaction vessel simultaneously at a mole
ratio of CO2 to alkaline earth metal base of about .40:1
to about .95:1 and at a controlled rate such that the rate
of charging the reactants is not substantially greater or
less than the rate at which the carbonation reaction can
proceed. If the rate i9 substantially faster than the
speed at which the carbonation can occur the reaction mix-
ture will become very viscous it will be difficult to con-
duct the carbonation due to formation of glycol oxide
complexes, and the resulting product will generally be
poorer in quality. If the rate of charging is substan-
35 tially slower than the rate at which the carbonation .
reaction can occur the reaction cycle time is unnecessar-
ily prolonged.
-11-
As an example, in the case of a commercial 3000
gallon stirred tank reactor, it has been determined that a
suitable rate for charging of the alkaline earth metal (in -
5 the form of a 480 TBN Ca(OH)2 ~lurry in 5W oil) is about ~-
70-90 lbs per minute; a suitable rate for the glycol
charge is about 10-15 lbs per minute and a suitable C02 -~
charge rate is about 7000 SCFH.
The mole ratio at which the CO2 and alkaline earth
metal base are charged to the reaction veqsel during the
carbonation step constitutes a critical feature of the
present invention. If the mole ratio of CO2 to metal base
being charged is below about .40 the reaction mixture will
become too viscous and difficult to process, and the
resultant product will have poor quality as evidenced by
water intolerance. At mole ratios greater than .95 there
is a danger of forming overcarbonated product which will
result in a hazy phenate product also characterized by
poor water tolerance properties. A preferred charge ratio
of CO2 to alkaline earth metal is about .75 to .85
The carbonation reaction can be conducted in the ~em-
perature range of about 300 to about 360F and preferably
from about 330 to about 350P. Preferably, the alkaline
earth metal base ~in 5W oil) is charged to the reaction
across a preheater set at the desired reaction temperature
for the carbonation.
After the alkaline earth metal base and glycol have
been completely charged to the reaction vessel, the CO2
charge is allowed to continue until the carbonation
reaction is complete. Completion is evidenced by off-gas
"breakthrough" i.e., a sharp increase in the reactor off
gas when the charged CO2 is no longer being absorbed into
the reaction medium. Generally, completion is deemed to
occur 5 minutes after the reactor off-gas exceeds 5000
SCFH.
Following carbonation, the overbased product can be
stripped to remove unreacted glycol and alkylphenol. This
- ~ , . ; , - ~ : .
-12-
is typically done under vacuum with a nitrogen purge at
400 to 480F. After stripping the product is filtered to
remove fine solids.
The overbased sulfurized phenates prepared accordlng
to the present invention are suitable as detergent/anti-
oxidant additives for lubricating oils, particularly those
used in marine diesel engines.
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EXAMPLE I
(Compasative)
In this example an overbased sulurized alkaline
earth metal alkylphenate is prepared using a batch method.
Eighty gallons of 5W oil weee charged into a commercial
3000 gallon stirred tank reactor. Into the reactor was
then charged 7300 lbs of a 180 T8N calcium hydroxide dode~
cylphenol slurry. This slurry was previously prepared by
combining 1700 gallon of dodecylphenol containing about
5.0 wt.~ of an alkaline earth metal sulfonate with 1740
lbs of Ca(OH)2 and 1 quart of a commercially obtainable
silicone antifoamant, to result in a slurry having a TBN
(total base number by ASTM D-2896) of 180. Simultaneously
with the charging of dodecylphenol calcium hydroxide
slurry to the reactor, 7128 lbs of ethylene glycol were
charged into the reactor. The reactor was then brought to
a temperature of 250F at which pointll50 lbs of molten
sulfur were charged to thereactor. The reactor was then
brought to a temperature of 330F and held there for 60
minutes to accomplish formation of the sulfurized calcium
phenate. A first stage of carbonate overbasing was then
undertaken by charging 3260 lbs of a 480 T8N slurry of
calcium hydroxide in 5W oil and 510 lbs of ethylene glycol
to the reactor. The 480 T8N slurry of calcium hydroxide
in 5W oil was previously prepared by mixing 1240 gallons
of 5W, 1 quart of antifoam, and 4140 lbs of Ca(OH)2 in a
suitable holdinq tank. ~ollowing the charge of the 480
T8N slurry and additional glycol the entire reaction mix-
ture was nitrogen stripped with 2000 SCFH ~2. Afternitrogen str-ipping the reaction mixture was carbonated
with 7000 SCFH CO2 until completion of the carbonation as
indicated by a sharp increase in the reactor off-gas.
Upon completion of the first carbonation stage a second
carbonation stage waS undertaken by introducing a second
charge (3260 lbs) of the 480 TBN calcium hydroxide/5W oil
slurry and ethylene glycol (510 lbs) into the reactor, ~
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-14-
followed by nitrogen stripping. The reaction mixture was
again carbonated with 7000 SCF8 CO2 until completion of
the carbonation aq evidenced by a sharp increase in off-
gas breakthrough. The reaction product was then stripped
in a conventional manner to remove unreacted glycol and -~
alkyphenol and then filtered to remove solid particles.
The final product had the Eollowing inspection: calcium
(wt.~) 9.4; sulfur (wt.~) 3.0; glycol ~wt.~) 0.1; carbo-
nate C (wt.~) 1.7: T~N (mg. ~OH/g) 267; PM Flash (F) 356;
viscosity (cSt at 100C) 151; ~S&W (Vol. ~) 0.02.
EXAMPLE II
(Comparative) ~-
In this example sulfurized overbased calcium phenate
was prepared in a continuous process utilizing two 3000
gallon reactors in series. To the first reactor con-
trolled at 350F were charged 32 lbs per minute of a 270
TPN calcium hydroxide dodecylphenol slurry, 3.4 lbs per
minute of ethylene glycol and 4.9 lbs per minute of
sulfur. To the second reactor, also controlled at 350F,
were charged reactor effluent from the first reactor via
level control, 46 lbs per minute of a 330 Ti3N calcium
hydroxide dodecylphenol slurry, 9.6 lbs per minute of
ethylene glycol, and 2300 SCFH CO2. Effluent from the
second reactor was continuously transferred via level con-
trol for stripping and filtration. The final product had
the following inspection: Calcium (wt.~) 9.4; Sulfur
(wt.~) 3.2; Glycol (wt.~) 0.1; Carbonate C (wt.%) 1.3; TBN
(Mg KOH/g) 254; PM Flash ~F) 350; Viscosity (cSt at
100C) 275; ~3S~W (Vol.~) <0.05.
: . :
EXAMPLE III -~
In this example an overbased suleurized calcium dode- ;-
cylphenate was prepared in accordance with the present
invention. Into a commercial 3000 gallon stirred tank
reactor ~as charged 80 qallons of 5W oil. Seven thcusand
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-15- ~ -
three hundred lbs of a 180 T8N calcium hydroxide dodecyl~
phenol slurry (refer to the slurry preparation in Example
I, above) was charged into the reactor through a preheater
set at 330CF in order to raise the temperature of the
slurry to 330F just prior to its introduction to the
reaction vessel. At the same time, but separately, 728
lbs of ethylene glycol were charged into the reactor.
Molten sulfur was then charged to the reaction vessel at
rate of 29 lbs per minute until a total of 1150 lbs were
charged. Following the 180 TBN slurry charge, 50 gallons
of 5W oil ~ere added to the reactor through the same line
used to charge the slurry. The reaction mixture was then
held for thirty minutes at 330F to accomplish formation
of the sulfurized calcium dodecylphenate intermediate.
Carbonation of the intermediate was then carried out by
charging a 480 T~3N calcium hydroxide/5W oil slurry (see
Example I for slurry preparation) to the reaction vessel
across a second preheater set at 330F and a charge rate
of 82 lbs per minute until a total of 6250 lbs of the
slurry had been charged. Charging of the 480 T~N slurry
was foliowed by a 50 gallon charge of 5W oil to the reac-
tor through the same line used to charge the slurry.
Simultaneously with charging of the 480 T8N Ca(OH)2/5W oil
slurry, charged separately were 1020 lbs of ethylene
glycol at a rate of 13 lbs per minute and separately
carbon dioxide gas at a rate of 7000 SCFH. Following com-
pletion of the 480 TaN slurry and glycol charges, the CO2
charge was allowed to continue until completion of the
carbonation. Carbonation was deemed completed 5 minutes
after the reactor off-gas exceeded 5000 SCFH. The prod-
uct, vacuum stripped with nitrogen at 480F and filtered
through Celite 535, had a final inspection as follows:
Calcium (wt.~) 9.4: Sulfur (wt.~) 2.9; Glycol ~wt.%) 0.6;
Carbonate C (wt.~) 1.8: T8N (mg ~OH/g) 272; PM ~lash (F)
360; Viscosity (cSt 100C) 106; 8S~W (Vol. ~) < 0.05.
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Table I below sets forth a comparison of the reaction
cycle times for the batch preparation of Example I and the
present invention's batch preparation described in Example
S III.
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TABLE I
Comparison of Reaction
5Cycle Time of Example I
and Example III
Process StepEx. IEx. III
(minutes)
1. Charge 5W oil, glycol and
180 TBN Ca(OH)2 in
Dodecylphenol Slurry65 65
2. Charge sulur 15 60
3. Heat reaction vessel to
330F for sulfurization
reaction. 120-180 0
4. Hold for reaction. 60 30
5. Charge 480 TBN slurry
of Ca~OH)2 in 5W oil
and glycol. 40 80
6. Strip with N2. 20 0
7. Carbonate to of-gas
breakthrough 60 40
8. Repeat steps 5 to 7.120 0 ;~
~- --
Reaction Cycle Time (min.)500-560 275
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-18-
Note that while both preparations processed the same
amount of reactants resulting in essentially equivalent
~uantity and quality of product, the improvements Oe the
prasent invention a~ carried out in Example IIr reduced
the reaction cycle time by 225 to 285 minutes. This sig-
nificant reduction is made possible by the novel and non-
obvious manner in which the sulfurization and carbonation
steps are carried out in the batch process of the present
invention. In particular, the two stage carbonation
required in the batch process of Example I i5 obviated in
the present invention by conducting carbonation at the
same time that the 480 T~N Ca(OH)2t5W oil slurry and
glycol are being charged to the reactor. This feature of
the invention circumvents the problem of high viscosity in
the batch reaction mixture, which problem necessitates a
two stage carbonation as used in Example I, while avoiding
the problem of over- or undercarbonation associated with a
continuous process such as that described in Example II,
which problem results in water tolerance difficulties in
the phenate product.
A comparison was made of the water tolerance of the
overbased phenate prepared in Example II (continuous proc-
ess) with the water tolerance of the overbased phenate
prepared by the present invention in Example III. Conven-
tional treat levels of the two phenates were incorporated
into a standard commercial lubricant formulation contain-
ing a major proportion of lube oil and a minor effective
amount of ashless dispersant, low base calcium sulfonate,
high base magnesium sulfonate, an oxidation inhibitor and
zinc dialkyldithiophosphate. The water tolerance of the
standard formulation containing the Example II overbased
phenate was compared to the standard formulation contain-
ing the Example III overbased phenate by measuring haze
and sediment in samples of the formulation aEter six weeks
of storage at ~ither 70F or 130F and at three diEferent
levels of water (0.10, 0.15, and 0.20 wt.~) in the formu-
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--19--
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lation. Thus, for each overbased phenate 5iX separate
samples of the standard formulation were tested. The
results of the water tolerance tests are summarized in
Table II, below.
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TABLE II
Water Tolerance Test
of Example II and
Example III Phenates
70F Storaqe 130F Storage
Water, wt.3 Rating~* Water, wt.% Ratinq
0.10 0.15 0.20 0.10 0.15 0.20
Ex. IIA/tr* A/tr M/15 Good A/tr M/15 M/20 Bdln
Ex. III A/tr A/tr A/tr Ideal A/tr A/tr M/20 Good
* Haze/sediment; Haze ratings begin with "A" for best
clarity and any rating of "D" or higher is considered
a failure. Sediment is measured in volume % and "tr"
means trace of sediment. Sediment > 1~ at any time
during six week storage is failure.
,
** The ratings are assigned as follows:
.
Rating Criteria
Ideal No haze or sediment at any water level.
Good Fails haze or sediment at 0.20% water.
Borderline Fails haze or sediment at 0.15~ water
30 Poor Fails haze or sediment at 0.10~ water.
The data set forth in Table II above demonstrate that
the process of the present invention (Example III) results
in an overbased phenate having significantly improved
water tolerance than the phenate produced in the contin-
uous process of Example II.
Y 7 ~ 3
~21- ~:
In view of the data set forth in Tables I and II
above, the process of the present invention can signif- :.
icantly increase the throughput o a batch process while
at the same time accomplishing the excellent water toler-
ance properties normally associated with a batch prepara- ~.
tion.
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