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Description  |
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This invention relates to new compositions of matter useful as
multi-purpose additives in lubricants, and to lubricants containing said
compositions. Briefly described, the invention comprises compositions
prepared by:
(A) Preparing a mixture comprising at least one oil-soluble dispersant and
at least one dimercaptothiadiazole and heating said mixture at a
temperature above about 100.degree. C. to convert it into an intermediate
capable of forming a homogeneous blend with an oleaginous liquid of
lubricating viscosity; and
(B) Reacting said intermediate, at a temperature within the range of about
50.degree.-200.degree. C., with at least one carboxylic acid or anhydride
containing up to about 10 carbon atoms and having at least one olefinic
bond.
The use of lubricant additives containing dimercaptothiadiazole groups,
especially 2,5-dimercapto-1,3,4-thiadiazole groups, to suppress copper
activity and "lead paint" deposition is known. Particular reference is
made to my copending application Ser. No. 470,483, now British Pat. No.
1,462,287, which describes multi-purpose additives prepared by reacting
the dimercaptothiadiazole with an oil-soluble dispersant. Such materials
may also serve as extreme pressure agents and corrosion inhibitors for
copper-lead bearings and have dispersant properties owing to the presence
of dispersant moieties therein.
A problem sometimes encountered in additive-containing lubricants is that
of compatibility between the various additives used. Occasionally it is
found that the presence of a particular additive or combination of
additives decreases somewhat the solubilities of other additives in the
lubricant, resulting in the formation of haze or sediment during storage.
Such haze or sediment formation is, of course, undesirable since the
insoluble material may be deposited on engine parts or elsewhere in the
machine being lubricated and the oil contains less additive than is
proper.
A principal object of the present invention, therefore, is to provide
improved multi-purpose additives for lubricants.
A further object is to provide additives which are compatible with a wide
variety of other additives.
Still another object is to provide nitrogen- and sulfur-containing
lubricant additives which suppress copper activity and "lead paint"
formation and also have dispersant properties and other beneficial
properties.
Other objects will in part be obvious and will in part appear hereinafter.
As previously noted, the compositions of this invention are prepared by a
two-step method in which the first step (step A) is the preparation of a
dispersant-dimercaptothiadiazole intermediate. The method for the
preparation of this intermediate is described in detail in the
above-mentioned British Pat. No. 1,462,287, which is incorporated by
reference herein for its description thereof.
The dimercaptothiadiazole used in step A is preferably
2,5-dimercapto-1,3,4-thiadiazole, referred to sometimes hereinafter as
DMTD. The oil-soluble dispersant is usually one of the materials known in
the art as "ashless dispersants", although, depending on its constitution,
the dispersant may upon combustion yield a non-volatile material such as
boric oxide or phosphorus pentoxide; however, it does not ordinarily
contain metal and therefore does not yield a metal-containing ash on
combustion.
Oil-soluble dispersants of many types are known in the art and are
described in various patents. Any of them are suitable for use in
preparing the intermediate. The following are illustrative:
(1) Reaction products of carboxylic acids (or derivatives thereof)
containing at least about 34 and preferably at least about 54 carbon atoms
with nitrogen-containing compounds such as amines, organic hydroxy
compounds such as phenols and alcohols, and/or basic inorganic materials.
Examples of these products, referred to herein as "carboxylic
dispersants", are described in British Pat. No. 1,306,529 and in many U.S.
patents including the following:
______________________________________
3,163,603 3,351,552 3,541,012
3,184,474 3,381,022 3,542,678
3,215,707 3,399,141 3,542,680
3,219,666 3,415,750 3,567,637
3,271,310 3,433,744 3,574,101
3,272,746 3,444,170 3,576,743
3,281,357 3,448,048 3,630,904
3,306,908 3,448,049 3,632,510
3,311,558 3,451,933 3,632,511
3,316,177 3,454,607 3,697,428
3,340,281 3,467,668 3,725,441
3,341,542 3,501,405 Re 26,433
3,346,493 3,522,179
______________________________________
(2) Reaction products of aliphatic or alicyclic halides containing at least
about 30 carbon atoms with amines, preferably polyalkylene polyamines.
These may be characterized as "amine dispersants" and examples thereof are
described, for example, in the following U.S. patents:
______________________________________
3,275,554 3,454,555
3,438,757 3,565,804
______________________________________
(3) Reaction products of alkyl phenols in which the alkyl group contains at
least about 30 carbon atoms with aldehydes (especially formaldehyde) and
amines (especially polyalkylene polyamines), which may be characterized as
"Mannich dispersants". The materials described in the following U.S.
patents are illustrative:
______________________________________
3,413,347 3,725,480
3,697,574 3,726,882
3,725,277
______________________________________
(4) Products obtained by post-treating the carboxylic, amine or Mannich
dispersants with such reagents as sulfur, urea, thiourea, carbon
disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted
succinic anhydrides, nitriles, epoxides, boron compounds, phosphorus
compounds or the like. Exemplary materials of this kind are described in
the following U.S. patents:
______________________________________
3,036,003 3,282,955 3,493,520 3,639,242
3,087,963 3,312,619 3,502,677 3,649,229
3,200,107 3,366,569 3,513,093 3,649,659
3,216,963 3,367,943 3,533,945 3,658,836
3,254,025 3,373,111 3,539,633 3,697,574
3,256,185 3,403,102 3,573,010 3,702,757
3,278,550 3,442,808 3,579,450 3,703,536
3,280,234 3,455,831 3,591,598 3,704,308
3,281,428 3,455,832 3,600,372 3,708,522
______________________________________
(5) Interpolymers of oil-solubilizing monomers containing a pendant alkyl
group having at least about 8 carbon atoms, such as decyl methacrylate,
vinyl decyl ether or a relatively high molecular weight olefin, with
monomers containing polar substituents, e.g., aminoalkyl acrylates,
aminoalkyl acrylamides or poly-(oxyalkylene)-substituted alkyl acrylates.
These may be characterized as "polymeric dispersants" and examples thereof
are disclosed in the following U.S. patents:
______________________________________
3,329,658 3,666,730
3,449,250 3,687,849
3,519,565 3,702,300
______________________________________
The pertinent disclosures of all of the above-noted patents are
incorporated by reference herein.
The carboxylic dispersants are the preferred ones for use in the
preparation of the compositions of this invention. They may be most
conveniently and accurately described in terms of radicals 1 and 2 present
therein. Radical 1 is at least one acyl, acyloxy or acylimidoyl radical
containing at least about 34 carbon atoms. The structures of these
radicals, as defined by the International Union of Pure and Applied
Chemistry, are as follows (R representing a hydrocarbon or similar group):
##STR1##
Radical 2 is preferably at least one radical in which a nitrogen or oxygen
atom is attached directly to said radical 1, said nitrogen or oxygen atom
also being attached to a hydrocarbon radical or substituted hydrocarbon
radical, especially an amino, alkylamino-, polyalkyleneamino-, hydroxy- or
alkyleneoxy-substituted hydrocarbon radical. With respect to radical 2,
the dispersants are conveniently classified as "nitrogen-bridged
dispersants" and "oxygen-bridged dispersants" wherein the atom attached
directly to radical 1 is nitrogen or oxygen, respectively.
The nitrogen-bridged dispersants, which will be described first, are those
disclosed (for example) in the above-mentioned U.S. Pat. Nos. 3,219,666
and 3,272,746 which also describe a large number of methods for their
preparation. The nitrogen-containing group therein is derived from
compounds characterized by a radical of the structure > NH wherein the two
remaining valences of nitrogen are satisfied by hydrogen, amino or organic
radicals bonded to said nitrogen atom through direct carbon-to-nitrogen
linkages. These compounds include aliphatic, aromatic, heterocyclic and
carbocyclic amines as well as substituted ureas, thioureas, hydrazines,
guanidines, amidines, amides, thioamides, cyanamides and the like.
Especially preferred as nitrogen-containing compounds used in the
preparation of the nitrogen-bridged dispersants are alkylene polyamines
and hydroxyalkyl-substituted alkylene polyamines. The alkylene polyamines
comprise, in general, alkylene amines containing about 10 or less alkylene
groups joined through nitrogen atoms. They include principally the
ethylene amines, propylene amines, butylene amines and homologs thereof,
and also piperazines and aminoalkyl-substituted piperazines.
Hydroxyalkyl-substituted derivatives of these alkylene polyamines are also
contemplated for use in preparing the nitrogen-bridged dispersant. Typical
examples of suitable amines are ethylene diamine, triethylene tetramine,
pentaethylene hexamine, propylene diamine, tripropylene tetramine,
di-(trimethylene)triamine, 1,4-bis-(2-aminoethyl)piperazine,
1-(2-aminopropyl)piperazine, N-(2-hydroxyethyl)ethylene diamine,
1-(2-hydroxyethyl)piperazine, and
2-heptadecyl-1-(2-hydroxyethyl)-imidazoline. Mixtures of these amines may
also be used.
The preferred amines are the polyethylene polyamines containing from two to
about eight amino groups per molecule. A commercially available mixture of
polyethylene polyamines containing an average of about 3-7 amino groups
per molecule is particularly suitable.
The acylating agent used for preparing the nitrogen-bridged dispersant is a
carboxylic acid-producing compound containing at least about 34 and
preferably at least about 54 carbon atoms. By "carboxylic acid-producing
compound" is meant an acid, anhydride, acid halide, ester, amide, imide,
amidine or the like; the acids and anhydrides are preferred.
The acylating agent is usually prepared by the reaction (more fully
described hereinafter) of a relatively low molecular weight carboxylic
acid-producing compound with a hydrocarbon-based source containing at
least about 30 and preferably at least about 50 carbon atoms. The
hydrocarbon-based source should be substantially saturated, i.e., at least
about 95% of the total number of carbon-to-carbon covalent linkages should
be saturated. It should also be substantially free from pendant groups
containing more than about six aliphatic carbon atoms.
As used herein, the term "hydrocarbon-based" denotes a radical which, upon
reaction as described hereinafter, will have a carbon atom directly
attached to the remainder of the molecule and which has predominantly
hydrocarbon character within the context of this invention. Such radicals
include the following:
(1) Hydrocarbon radicals; that is, aliphatic, (e.g., alkyl or alkenyl),
alicyclic (e.g., cycloalkyl or cycloalkenyl), aromatic, aliphatic- and
alicyclic-substituted aromatic, aromatic-substituted aliphatic and
alicyclic radicals, and the like, as well as cyclic radicals wherein the
ring is completed through another portion of the molecule (that is, any
two indicated substituents may together form an alicyclic radical).
(2) Substituted hydrocarbon radicals; that is, radicals containing
non-hydrocarbon substituents which, in the context of this invention, do
not alter the predominantly hydrocarbon character of the radical but which
frequently act as activating radicals for the reaction with the low
molecular weight acid-producing compound as described hereinafter. Those
skilled in the art will be aware of suitable substituents; examples are
halo, hydroxy, ether, aldehydo, keto, carboxy, ester (especially lower
carbalkoxy), amide, nitro, cyano, mercaptan, sulfide, disulfide, sulfoxy
and sulfone. Halo and especially chloro substituents are preferred.
(3) Hetero radicals; that is, radicals which, while predominantly
hydrocarbon in character within the context of this invention, contain
atoms other than carbon present in a chain or ring otherwise composed of
carbon atoms. Suitable hetero atoms will be apparent to those skilled in
the art and include, for example, nitrogen, oxygen and sulfur.
In general, no more than about three substituents or hetero atoms, and
preferably no more than one, will be present for each 10 carbon atoms in
the hydrocarbon-based radical.
The preferred hydrocarbon sources are those derived from substantially
saturated petroleum fractions and olefin polymers, particularly polymers
of monoolefins having from 2 to about 30 carbon atoms. Thus, the
hydrocarbon source may be derived from a polymer of ethylene, propene,
1-butene, isobutene, 1-octene, 3-cyclohexyl-1-butene, 2-butene, 3-pentene
or the like. Also useful are interpolymers of olefins such as those
illustrated above with other polymerizable olefinic substances such as
styrene, chloroprene, isoprene, p-methylstyrene, piperylene and the like.
In general, these interpolymers should contain at least about 80%,
preferably at least about 95%, on a weight basis of units derived from the
aliphatic monoolefins.
Another suitable hydrocarbon source comprises saturated aliphatic
hydrocarbons such as highly refined high molecular weight white oils or
synthetic alkanes.
As already pointed out, the hydrocarbon-based source generally contains at
least about 30 and preferably at least about 50 carbon atoms. Among the
olefin polymers those having a molecular weight of about 700-5000 are
preferred, although higher polymers having molecular weights from about
10,000 to about 100,000 or higher may sometimes be used. Especially
suitable as hydrocarbon-based sources are butene polymers within the
prescribed molecular weight range containing predominantly isobutene
units, and chlorinated derivatives thereof.
Any one of a number of known reactions may be employed for the
incorporation of the hydrocarbon-based source into the acid-producing
compound to provide the required acylating agent. Thus, an alcohol of the
desired molecular weight may be oxidized with potassium permanganate,
nitric acid or a similar oxidizing agent; a halogenated olefin polymer may
be reacted with a ketene; an ester of an active hydrogen-containing acid,
such as acetoacetic acid, may be converted to its sodium derivative and
the sodium derivative reacted with a halogenated high molecular weight
hydrocarbon such as brominated wax or brominated polybutene; a high
molecular weight olefin may be ozonized; a methyl ketone of the desired
molecular weight may be oxidized by means of the haloform reaction; an
organo-metallic derivative of a halogenated hydrocarbon may be reacted
with carbon dioxide; a halogenated hydrocarbon or olefin polymer may be
converted to a nitrile, which is subsequently hydrolyzed; or an olefin
polymer or its halogenated derivative may undergo an addition reaction
with an unsaturated acid or derivative thereof. This latter reaction is
preferred, especially where the acid-producing compound is maleic acid or
anhydride. The resulting product is then a hydrocarbon-substituted
succinic acid or derivative thereof. The reaction leading to its formation
involves merely heating the two reactants at about 100.degree.-200.degree.
C. The substituted succinic acid or anhydride thus obtained, may, if
desired, be converted to the corresponding acid halide by reaction with
known halogenating agents such as phosphorus trichloride, phosphorus
pentachloride or thionyl chloride.
For the formation of the nitrogen-bridged dispersant, the
hydrocarbon-substituted succinic anhydride or acid, or other acylating
agent, and the alkylene polyamine or other nitrogen-containing reagent are
heated to a temperature above about 80.degree. C., preferably about
100.degree.-250.degree. C. The product thus obtained has predominantly
amide, imide and/or amidine linkages (containing acyl or acylimidoyl
groups). The process may in some instances be carried out at a temperature
below 80.degree. C. to produce a product having predominantly salt
linkages (containing acyloxy groups). The use of a diluent such as mineral
oil, benzene, toluene, naphtha or the like is often desirable to
facilitate control of the reaction temperature.
The relative proportions of the acylating agent and the alkylene polyamine
or the like are such that at least about one-half the stoichiometrically
equivalent amount of polyamine is used for each equivalent of acylating
agent. In this regard, it will be noted that the equivalent weight of the
alkylene polyamine is based upon the number of amine radicals therein, and
the equivalent weight of the acylating agent is based on the number of
acidic or potentially acidic radicals. (Thus, the equivalent weight of a
hydrocarbon-substituted succinic acid or anhydride is one-half its
molecular weight.) Although a minimum of one-half equivalent of polyamine
per equivalent of acylating agent should be used, there does not appear to
be an upper limit for the amount of polyamine. If an excess is used, it
merely remains in the product unreacted without any apparent adverse
effects. Ordinarily, no more than about 2 equivalents of polyamine are
used per equivalent of acylating agent.
Especially preferred for the purposes of this invention are substantially
neutral or acidic dispersants; that is, dispersants having a base number
less than 7 or an acid number when titrated to a bromphenol blue end
point. ("Acid number" is the number of milligrams of potassium hydroxide
required for titration of a 1-gram sample, and "base number" is the number
of milligrams of potassium hydroxide equivalent to the amount of acid
required for titration of a 1-gram sample.) Nitrogen-bridged dispersants
of this type may often be prepared by using one equivalent or less of
polyamine per equivalent of acylating agent.
In an alternative method for producing the nitrogen-bridged dispersant, the
alkylene polyamine is first reacted with a low molecular weight,
unsaturated carboxylic acid-producing compound such as maleic anhydride
and the resulting intermediate is subsequently reacted with the
hydrocarbon source as previously described.
Oxygen-bridged dispersants comprise the esters of the above-described
carboxylic acids, as described (for example) in the aforementioned U.S.
Pat. Nos. 3,381,022 and 3,542,678. As such, they contain acyl or,
occasionally, acylimidoyl radicals as radical 1. (An oxygen-bridged
dispersant containing an acyloxy radical as radical 1 would be a peroxide,
which is unlikely to be stable under all conditions of use of the
compositions of this invention.) These esters are preferably prepared by
conventional methods, usually the reaction (frequently in the presence of
an acidic catalyst) of the carboxylic acid-producing compound with an
aliphatic compound such as a monohydric or polyhydric alcohol or with an
aromatic compound such as a phenol or naphthol. The preferred hydroxy
compounds are alcohols containing up to about 40 aliphatic carbon atoms.
These may be monohydric alcohols such as methanol, ethanol, isooctanol,
dodecanol, cyclohexanol, neopentyl alcohol, monomethyl ether of ethylene
glycol and the like, or polyhydric alcohols including ethylene glycol,
diethylene glycol, dipropylene glycol, tetramethylene glycol,
pentaerythritol, glycerol and the like. Carbohydrates (e.g., sugars,
starches, cellulose) and also suitable as are partially esterified
derivatives of polyhydric alcohols having at least three hydroxy radicals.
The reaction is usually effected at a temperature above about 100.degree.
C. and typically at 150.degree.-300.degree. C. The esters may be neutral
or acidic, or may contain unesterified hydroxy groups, according as the
ratio of equivalents of acid-producing compound to hydroxy compound is
equal to, greater than or less than 1:1.
As will be apparent, the oxygen-bridged dispersants are normally
substantially neutral or acidic. They are among the preferred dispersants
for the purposes of this invention.
It is possible to prepare mixed oxygen- and nitrogen-bridged dispersants by
reacting the acylating agent simultaneously or, preferably, sequentially
with nitrogen-containing and hydroxy reagents such as those previously
described. The relative amounts of the nitrogen-containing and hydroxy
reagents may be between about 10:1 and 1:10, on an equivalent weight
basis. The methods of preparation of the mixed oxygen- and
nitrogen-bridged dispersants are generally the same as for the individual
dispersants described, except that two sources of radical 2 are used. As
previously noted, substantially neutral or acidic dispersants are
preferred, and a typical method of producing mixed oxygen- and
nitrogen-bridged dispersants of this type (which are especially preferred)
is to react the acylating agent with the hydroxy reagent first and
subsequently react the intermediate thus obtained with a suitable
nitrogen-containing reagent in an amount to afford a substantially neutral
or acidic product.
Typical carboxylic dispersants suitable for use in preparing the
intermediate are listed in Table I. "Reagent 1" and "Reagent 2" are,
respectively, the sources of radicals 1 and 2 as previously defined. The
dispersants of Examples 1-6, 8, 9, 12 and 14-17 are basic; those of the
other examples are substantially neutral or acidic.
TABLE I
__________________________________________________________________________
Ratio of
Reaction Acid or
equivalents,
temperature, base
Example
Reagent 1 Reagent 2 1:2 .degree. C.
Diluent
no.
__________________________________________________________________________
1 Polyisobutenyl (mol. wt.)
Polyethylene amine
0.48 150 Mineral oil
50B
about 900) succinic an-
mixture containing
hydride prepared from
about 3-7 amino groups
chlorinated polyisobutene
per molecule
2 Same as Example 1
Pentaethylene hexamine
0.41 150 Mineral oil
82B
3 Like Example 1 except
Pentaethylene hexamine
0.61 150 Mineral oil
130B
polyisobutene mol. wt.
is about 1050
4 Like Example 1, except
Diethylene triamine
1.0 150 Mineral oil
19B
polyisobutene mol. wt.
is about 850
5 Same as Example 4
Ethylene diamine
1.0 150 Mineral oil
19B
6 Same as Example 4
Di-(1,2-propylene)
1.0 180-190
Mineral oil-
--
triamine toluene
7 Same as Example 4
N-(2-hydroxyethyl)-
1.06 150-155
Mineral oil
4A
trimethylene diamine
8 Tetrapropenyl succinic
Triethylene tetramine
1.0 155 Toluene
60B
anhydride
9 Same as Example 1
Same as Example 1
0.67 150 Mineral oil
35B
10 Same as Example 1
Same as Example 1
1.33 150 Mineral oil
6B
11 Like Example 1, except
Pentaerythritol, followed
0.44 150-210
Mineral oil
2B
polyisobutene mol. wt.
by polyethylene amine of
is about 1100 Example 1 (ratio of
equivalents 7.7:1)
12 Isostearic acid
Pentaethylene hexamine
0.8 150 Mineral oil
8B
13 Acid produced by reaction
Ethylene diamine
2.0 150 Xylene
--
of chlorinated (3.6% Cl)
polyisobutene (mol. wt.
750) with KCN, followed
by hydrolysis
14 Methyl ester produced
Triethylene tetramine
1.0 140-220
-- --
by reaction of chlori-
nated (4.7% Cl) poly-
isobutene (mol. wt.
1000) with methyl
methacrylate
15 Reaction product of
Same as Example 1
0.4 150 Xylene
--
sodiomalonic ester with
C.sub.75 brominated wax
16 Reaction product of
Pentaethylene hexamine
0.8 180-200
-- --
chlorinated (4.5% Cl)
polyisobutene (mol. wt.
850) with acrylic acid
17 Acid produced by haloform
Same as Example 1
0.8 180-210
-- --
reaction with methyl
heptacontanyl ketone
18 Same as Example 11
Pentaerythritol
0.5 150-210
Mineral oil
--
19 Like Example 1, except
Neopentyl glycol
1.0 240-250
-- --
polyisobutene mol. wt.
is about 1000
20 Same as Example 19
Methanol* Excess
50-65 Toluene
--
methanol
21 Same as Example 19
Polyethylene glycol
2.0 240-250
-- --
(mol. wt. about 600)
22 Same as Example 19
Oleyl alcohol**
1.0 150-173
Xylene
0
23 Like Example 16, except
Sorbitol 0.48 115-205
Mineral oil
--
polyisobutene mol. wt.
is about 982
24 Same as Example 23
Pentaerythritol
1.0 180-205
-- --
25 Reaction product of poly-
Mannitol 0.33 115-205
Mineral oil
--
isobutene (mol. wt. 1500)
with chloroacetyl
chloride
*Hydrogen chloride catalyst
**p-Toluenesulfonic acid catalyst
The intermediate is formed by preparing a mixture of DMTD and the
dispersant and heating said mixture at a temperature above about
100.degree. C., usually about 100.degree.-250.degree. and especially about
120.degree.-200.degree., for a period of time sufficient to provide a
product which is capable of forming a homogeneous blend with an eleaginous
liquid of lubricating viscosity, such as a lubricating oil or synthetic
lubricant. The mixture will usually also contain an organic liquid diluent
which may be either polar or non-polar.
The relative amounts of dispersant and DMTD in the intermediate may vary
widely, as long as a homogeneous product is ultimately obtained. Thus,
about 0.1-10 parts by weight of dispersant may be used per part of DMTD.
Most often, about 5-10 parts of dispersant are used per part of DMTD. The
product usually contains DMTD moieties in amounts substantially greater
than the stoichiometric amount based on salt formation. If the dispersant
is neutral or acidic there is, of course, no "stoichiometric amount" of
DMTD and any amount thereof in the product is present in excess. If the
dispersant is basic, the product usually contains at least about a
five-fold excess and may contain a 500-fold or even greater excess of DMTD
moieties, based on the stoichiometric amount.
The preparation of the intermediate is illustrated by the following
examples. All parts and percentages are by weight. The weight ratios of
dispersant to DMTD referred to are, in each instance, initial ratios.
Equivalents of base in the dispersant are calculated from the base number.
EXAMPLE 26
Six thousand parts of the dispersant of Example 10 (0.64 equivalent of
base) is heated to 100.degree. C., and 484 parts of wet DMTD (420 parts on
a dry basis, or 5.6 equivalents) is added over 15 minutes, with stirring.
The mixture is heated at 110.degree.-120.degree. for 6 hours under
nitrogen, during which time hydrogen sulfide evolution is noted. Mineral
oil, 1200 parts, is added and the mixture is filtered while hot. The
filtrate is a 53% solution of the desired intermediate in oil and contains
1.68% nitrogen and 2.83% sulfur. The weight ratio of dispersant to DMTD is
8.6.
EXAMPLE 27
DMTD (5.6 equivalents) is pr | | |
