Note: Descriptions are shown in the official language in which they were submitted.
~ 9 ~ 215 0 5 ~ 6 PCT~S94/01952
AOUEOUS DEFOAMER DISPERSIONS OF ETHYLENEBIS(STEARAMIDE)
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to substantially oil-free
d amide based aqueous compositions which are effective defoamers
for use in paper mill operations, particularly for use on paper
machines and in the presence of dilute black liquors. The term
"oil" is used herein to refer to all hydrocarbon materials which
are liquid at room temperature and specifically includes fluids
such as mineral oils, benzene, heptane, octane, mineral seal
oil, stoddard solvent, petroleum naphtha, toluene, xylene,
paraffinic mineral oil, naphthenic mineral oil, and the like.
Description of the Prior Art
The problem of foam control in paper mills operations is a
continuing one. Generally, it has been most effectively dealt
with by using various oil-based compositions containing an
alkylene diamide and/or hydrophobic silica (silicone coated
silica). Oil-based amide defoamers contain a minimum of two
ingredients: a wax with a high melting point (usually a fatty
diamide) dispersed in a liquid hydrocarbon oil carrier, c.f.
U.S. Patent No. 3,677,963. The most commonly used diamide is
ethylenebis(stearamide), but other diamides or mixtures of
diamides can also be found in defoamer blends. Typically, the
weight fraction of diamides is between 4 and 12% whereas the
weight fraction of the hydrocarbon oil is well over 80%. The
oil carrier varies in composition from one defoamer to another
but generally consists of a low viscosity mineral oil with
paraffinic or cycloparaffinic hydrocarbons. In addition to the
diamides and oil, the blends may also contain other agents such
as hydrophobic silica and silicone oil, various emulsifiers and
stabilizers, but these these constituents generaliy comprise
less than 10% of the formulation. U.S. Patent No. 3,723,342,
for instance, discloses a defoamer composition containing 4 to
12% EBS, a surfactant, a silicone oil, and a low viscosity
mineral oil. U.S. Patent No. 4,032,473 discloses an aqueous
emulsion of a dispersed phase containing a liquid hydrocarbon,
. WOg4/20680 PCT~S94/01952 ~
2150~6
EBS, hydrophobic silica particles, and a nonionic emulsifier.
U.S. Patent No. 4,225,456 discloses a water-in-oil emulsion
defoamer composition containing quickchilled EBS, silica, a
water-soluble polymer, an emulsifier, oil and water.
While these and other similar compositions are effective
defoamers for brown stock washers in pulp mills, they have
recently been suspected of contributing to deposition problems
in various locations in paper mills. (Dorris et al. "Analysis
of Amide Defoamers in Kraft Mill Pitch Deposits," J.Pulp & Paper
Science, 11:5, J149-J154, September 1985.) And recently there
has been evidence that they are an indirect source of the
2,3,7,8-tetrachlorodibenzop-dioxin (TCDD) and
2,3,7,8-tetrachlorodibenzofuran (TCDF) produced in kraft bleach
plants. (Allen et al. manuscript distributed at the 8th
International Symposium on Chlorinated Dioxins and Related
Compounds, Umes, Sweden, August 21-26, 1988.) In addition, due
to the large oil content, i.e. generally at least about 20 wt %
but more commonly at least about 75 wt %, they have not been
found useful on paper machines because they are not able to
completely disperse in water and thus they cause deposits and/or
oil spots on the paper being produced.
U.S. Patent No. 3,652,453 discloses bis(stearamide)-based
defoamer compositions which utilizes the bis(stearamide) in the
form of a "quick-chilled amide" which is prepared by using a
"liquid hydrocarbon vehicle" such as benzene, toluene, heptane,
octane, mineral oil, and the like. These liquid hydrocarbon
vehicles are oils, as defined herein. In the defoamer composi-
tions produced in the eight '453 Examples, one or more oils is
present in an amount ranging from a low of about 85.3 wt % to a
high of about 95.55 wt % of the final defoamer compositions.
Alternative oil-based defoamers have been prepared from a
wide variety of chemicals. For example, U.S. Pat. No. 3,751,373
and 3,935,121 disclose defoamers based upon a combination of a
fatty acid or alcohol, a polyethylene glycol mono or di ester of
a fatty acid, a petroleum sulfonic acid, and 65-98% organic
~ 21 S 0 5 5 6 PCT~S94/01952
liquid. One example of a commercial aqueous defoamer is an
aqueous emulsion of fatty alcohols - although it does not con-
tain any oil phase, it does contain high melting waxes which are
known to interfere with certain later processing steps. These
defoamers are generally not as effective as those containing EBS
and its homologues, but also do not cause the spotting problem
on paper machines.
Therefore there is a need for a defoamer composition which
utilizes EBS and/or other diamides, since they are such effec-
tive defoamers, while minimizing the oil content or more prefer-
ably excluding the presence of any oil from the compositions.
It is an object of the present invention to produce such
defoamer compositions and to utilize them in paper-making
operations.
SUMMARY OF THE INVENTION
The present invention is a substantially oil-free aqueous
defoamer composition which comprises an aliphatic diamide, an
amphipathic liquid, and water. The defoamer composition is
prepared by heating the aliphatic diamide to above its melting
point in the presence of the amphipathic liquid and then adding
that mixture to the water. A uniform dispersion/emulsion of the
aliphatic diamide in water is produced and this dispersion/emul-
sion is an effective defoamer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The defoamer compositions of the present invention are
produced by combining an aliphatic diamide, an amphipathic
liquid, and water in such a manner that a uniform dispersion of
the aliphatic diamide in the water occurs while avoiding the
incorporation of any substantial amounts of an oil. The term
"oil" is used herein to refer to all hydrocarbon materials which
are liquid at room temperature and specifically includes fluids
such as mineral oils, benzene, heptane, octane, mineral seal
oil, stoddard solvent, petroleum naphtha, toluene, xylene,
paraffinic mineral oil, naphthenic mineral oil, and the like.
W094/20680 PCT~S94/01952 _
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Aliphatic diamides useful in the present compositions
include those obtained by reacting a polymethylene diamine con-
taining from 2 to about 6 methylene groups with a fatty acid,
i.e. a long chain aliphatic carboxylic acid having about lO to
about 22 carbon atoms in the chain. The acid may contain
straight or branched chains, may have a degree of unsaturation,
and may contain cycloaliphatic rings. Such fatty acids include
capric, lauric, myristic, palmitic, stearic, arachidic, behenic,
lauroleic, oleic, linoleic, linolenic, etc. It is customary,
but not essential, that the same acid form the amide group at
each of the amine groups in the polymethylenediamine. Aliphatic
diamides based on fatty acids having about 16 to about 18 carbon
atoms are preferred. A particularly preferred fatty acid
diamide is the diamide formed from stearic acid and ethylene
diamine, i.e. N,N'-ethylene bis(stearamide), hereafter referred
to as EBS.
Amphipathic liquids useful in the present invention are
those liquids having a sufficient amount and balance of both
polar and nonpolar groups so as to enable the aliphatic diamide
component to remain in suspension when added to water. The
amphipathic liquid provides sufficient wetting to the surfaces
of the aliphatic diamide particles to allow them to remain
dispersed when added to the water. Classes of suitable
amphipathic liquids useful herein include polyethylene glycol
mono and di esters of fatty acids wherein the polyethylene
glycol has a molecular weight of at least 300 and the fatty
acids have about 14 to about 22 carbon atoms, petroleum
sulfonates, and straight and branched chain alcohols having
about 10 to 14 carbon atoms and reacted with an amount of
ethylene oxide sufficient to produce a stable dispersion.
Examples of specific amphipathic liquids useful herein include
polyethylene glycol (400) monooleate, polyethylene glycol (600)
dioleate, sodium petroleum sulfonate, and dodecyl alcohol
reacted with 4 to 6 moles of ethylene oxide.
In addition to the aliphatic diamides and the amphipathic
liquid, the defoamer compostitions of this invention may further
~ 94/20680 21 S O ~ 5 ~ PCT~S94/019$
contain small amounts of one or more oil-soluble non-ionic
surfactants and/or polymers to improve the efficiency of the
defoamer compositions. The non-ionic oil-soluble surfactants
have been used with oil-based diamide defoamers as spreading
agents. Examples of suitable non-ionic materials include
condensation products of higher fatty alcohols with ethylene
oxide, condensation products of alkyl phenols with ethylene
oxide, condensation products of fatty acid amides with ethylene
oxide, polyethylene glycol esters of long chain fatty acids,
ethylene oxide condensation products of polyhydric alcohol
partial higher fatty acid esters and their inner anhydrides,
long chain polyglycols in which one hydroxyl group is esterified
with a higher fatty acid and the other hydroxyl group is etheri-
fied with a low molecular weight alcohol, propylene glycol mono
and di lower esters and ethers, ethylene oxide-propylene oxide
block copolymers, vinyl acetate based copolymers such as
Paratone 440 of Exxon Chemical, esters of ethylene oxide-
propylene oxide block copolymers, polybutenes, ethylene-
propylene rubbers, and the like. Preferably, these compounds
will be used in mixtures to obtain optimum properties for a
particular defoamer composition for a particular end use.
Routine experimentation will determine the specific non-ionic
oil-soluble materials to be used for a particular application.
These materials, if present, will generally represent less than
about 5, preferably less than about 3, wt % of the final
composition.
Although preferably no oil is present in the defoamer
compositions of this invention, the incorporation of small
amounts thereof generally as a carrier for the non-ionic oil-
soluble materials has not been found detrimental. The
compositions thus even though they may contain up to about 3 wt
%, preferably up to about 1 wt %, oil are substantially oil-free
as compared to prior art bis(stearamide) defoamer compositions
which contain at least 20 wt % oil and more commonly about 80 to
95 wt % oil.
WOg4/20680 PCT~S94/01952 _
5 ~ ~ ~ 6 ~
Furthermore, the compositions may also contain other
conventional defoamer additives such as hydrophobic silica,
anionic and cationic surfactants, waxes, fatty alcohols, and
fatty acids. The other materials, if present, will normally
represent less than about 3 weight % of the total defoamer
compositions. ~'
Generally the aliphatic diamides will be used in amounts
ranging from about 1 to 15, preferably about 2 to about 10,
weight % of the defoamer composition. The amphipathic liquid
will generally be used in an amount of about 10 to about 35,
preferably about 15 to about 30, and most preferably about 17 to
about 25, weight ~. The non-ionic oil-soluble surfactants and
polymers will be used in amounts up to a total of about 5 weight
%. The balance of the compositions will be water. For ready
incorporation into currently used defoamer equipment, the
defoamer compositions will generally have a viscosity of about
1,000 to about 2,500 centipoise as determined by a Brookfield
RVT viscometer using spindle number 3 at 50 rpm.
To prepare the defoamer compositions, the aliphatic diamide
is heated to above its melting point in the presence of the
amphipathic liquid. The heating continues with routine stirring
until the diamide has completely dissolved. The diamide-amphi-
pathic liquid solution is then poured into stirred water and
stirring is continued until a smooth creamy white dispersion is
obtained, i.e. for a few hours or even overnight. The water
will generally be at about room temperature when the diamide
solution is added to it, but this has not been found to be
critical. The diamide solution may be added either hot or after
it has cooled to room temperature. The non-ionic oil-soluble
materials, if used, may be added either to the diamide solution
before its addition to the water or to the final dispersion with
additional stirring.
The substantially oil-free defoamer compositions of this
invention have particular utility in controlling foam, i.e.
inhibiting foam formation and destroying existing foam, in a
~ 94~U~ 215 0 ~ ~ ~ PCT~S94/01952
variety of pulp and paper mill operations. Generally, these
defoamers will find primary use in treating foams that could
previously not be treated with diamide defoamers due to the
deposit problem referred to above. The defoamer compositions
are especially useful for controlling foam which occurs in
dilute black liquors. By "dilute" is meant that the concentra-
tion of total solids in the liquid phase is generally below
about 5 %, preferably below about 2 %, and most preferably below
a~out l %, all by weight. As such they may be used in
controlling foam in screen rooms, on paper machines, in paper
coatings, and to treat the plant effluent which is going to a
waste treatment facility.
The defoamer composition may be added to the system neat,
or it may be prediluted or it may be added on the fly. Since the
present defoamer compositions are completely water-dispersible,
they may be handled in like manner to other water-based
defoamers, even though they contain aliphatic diamides.
The quantity of the defoamer compositions required to
control foam will obviously vary depending upon the specific
nature of the liquid to be treated and upon the individual com-
ponents used to prepare the defoamers. Generally, however, a
quantity of defoamer from about 0.5 to 3 pounds per ton of pulp
will be suitable, preferably about l to about 2 pounds.
The following examples are presented for purposes of
illustration and not limitation. All parts and percents are by
weight unless otherwise specified.
EXAMPLE I
A mixture of l.o g ethylenebis(stearamide) and 24.0 g
polyethylene glycol (600) di-oleate is stirred and heated to
approximately 140 C. When all of the EBS has dissolved, the hot
solution is poured slowly into 75.0 g well-stirred room-tempera-
ture water. The temperature of the resulting dispersion is
about 40 C. It is inhomogeneous, i.e. lumpy, but becomes
smooth and homogeneous with continued stirring. The resulting
W094/20680 ~ ~ PCT~S94/01952 ~
21505~ 8
dispersion is stable and does not separate upon standing over a
period of three weeks.
EXAMPLE II
The procedure of Example I is repeated to produce 5 gallons
of a defoamer composition which contains 3% ethylenebis-
(stearamide), 22% polyethylene glycol (600) dioleate, and 75%
water.
To evaluate the defoaming ability of the composition, a
test is performed in the screen room of a paper mill. In the
test, the addition of the defoamer is controlled by a computer
which reads information on the height of the foam in the system.
The defoamer is added at a constant rate, and when the foam
level reaches or exceeds a preset level, the speed of the
defoamer pump is increased to add more defoamer until the foam
level drops below the preset level. Then the pump speed is
reduced to its original setting. The performance of the
defoamer is determined by calculating the pounds of defoamer
used per minute of operation.
In this test, 3l.3l pounds of the defoamer composition is
used in 2l minutes of operation. At no point during the test
does the foam exceed the preset level. The efficiency of the
defoamer is therefore l.49 pounds per minute. The commercially
used defoamer at this plant is Discotech 5543 from Callaway
Chemical and it is used in the screen room at a rate ranging
from about l.43 to about l.70 pounds per minute. Thus the
defoamer of this example is equivalent in performance to the
commercial product.
EXAMPLE III
The procedure of Example II is repeated with a variety of
defoamer compositions within the scope of this invention. The
respective formulations and efficiencies are provided in Tables
A and B below. As can be seen, the defoamers of the present
invention are consistently superior to the commercial defoamer
now used at this plant. Since, in no case with the present
~ 094~680 215 0 5 5 ~ PCT~S94tO1952
defoamers did the foam exceed the mill's preset level, the
amount of defoamer actually required for this use is below these
a~ounts.
TABLE A
i Formulations of ExamPle III
Component _ B C D E F G H
EBS 3 3 3 3 3 3 3 3 3
PEGDO (1) 21 21 20 21 20 21 20 20
Water 75 75 75 75 75 75 75 75 75
VAc (2)
PPGM8E (3)
SPS (4) 22
DOEEO/PO (5)
EO/PO (6)
(1) PEGD0 is polyethylene glycol (600) di-oleate
(2) VAc is an oil-soluble vinyl acetate-based copolymer
(3) PPGMBE is polypropylene glycol monobutyl ether
(4) SPS is sodium petroleum sulfonate
(5) DOEEO/PO is a di-oleate ester of an ethylene oxide/propylene
oxide block copolymer
(6) EO/PO is an ethylene oxide/propylene oxide block copolymer
TABLE B
Results of Example III
SamPle Lbs.Used Time(min.) Lbs./Min.
A 37.52 26 1.44
B 33.68 25.75 1.31
C 35.54 30 1.18
D 34.22 51.5 0.66
E 35.98 43.5 0.83
F 34.88 31 1.13
G 35.54 27 1.32
H 35 28.75 1.22
I 35.98 26 1.38
EXAMPLE IV
'~ The procedure of Example I is repeated to produce a defoamer
composition containing 4% EBS, 19% polyethylene glycol (400)
`- monooleate, 75% water, 1% oil-soluble vinyl acetate-based
copolymer in mineral oil (Paratone 440 of Exxon Chemical which
contains about 30% copolymer), and 1% ethylene oxide/propylene
oxide block copolymer. The composition contains about 0.7% oil.
W094/20680 PCT~S94/01952~
2~5~5~ _
To evaluate the performance of this composition at defoaming
on a paper machine, the above composition is substituted
directly for the commercial fatty alcohol-based defoamer on a
paper machine. The grade of paper being produced is unbleached
linerboard. The defoamer is added without prior dilution to
both the headbox and the wire pit. During a trial with a total
of five gallons of the defoamer composition, the usage was at a
rate of l.5 pounds per ton of dry paperboard produced. In this
plant, the commercial fatty alcohol-based defoamer is normally
used at a rate of 2 lbs./ton of dry paperboard.
The defoamer composition is more effective than the commer-
cial defoamer customarily used and leaves no deposits on either
the paper or the machine.
EXAMPLE V
The procedure of Example I is repeated using a variety of
different amphipathic liquids to dissolve the EBS. The composi-
tions contain 3 parts EBS, 22 parts amphipathic liquid, and 75
parts water. The following results, wherein EO stands for
ethylene oxide, are observed:
Amphipathic Liquid Stable Dispersion?
Dodecyl alcohol - 2 moles EO No
Dodecyl alcohol - 3 moles EO No
Dodecyl alcohol - 4 moles EO Yes
Dodecyl alcohol - 5 moles EO Yes
Dodecyl alcohol - 6 moles EO Yes
Dodecyl alcohol - 7 moles EO No
Dodecyl alcohol - 9 moles EO No
Polypropylene glycol (700) distearate No
Polyethylene glycol (200) dioleate No
Polyethylene glycol (400) monooleate Yes
~ 94/2~80 2 1:~ O ~ ~ 6 PCT~S94tO1952
EXAMPLE VI
The procedure of Example I is repeated except that the EBS
solution is cooled to room temperature before it is added to the
water. The resultant dispersion is as stable as that of Example
~J I showing that the rapid cooling provided by the water is not
required to produce the defoamers of this invention.
EXAMPLE VII
The procedure of Example II is repeated to produce two com-
positions for extended testing in the screen room. The composi-
tions both contain 3% EBS, 19% polyethylene glycol (600) diole-
ate, 75% water, 1% oil-soluble vinyl acetate-based copolymer, 1%
polypropylene glycol monobutyl ether, and 1~ ethylene oxide -
propylene oxide block copolymer. They differ only in when the
three 1% additions are made - in the first case ("before") they
are added to the hot EBS solution before its addition to the
water, while in the other ("after") they are added after the
addition to water. The two compositions are evaluated versus
the commercial defoamer and the results are:
Sample Lbs.Used Time(min.) Lbs./Min.
Before 72.38 77.75 0.93
After 74.15 68 1.09
Commercial 45 25 1.80
Thus, the compositions of the present invention are
substantially improved defoamers as compared to the commercial
product currently in use at this paper mill. No substantial
difference is seen based upon when the minor additions are made.
