Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1 324058
~ PARTICULATE STABILIZED ANTI-FOAM COMPOSITIONS AND METHODS
BACKGROUND OF TIIE INVENTION
This invention relates to new compositions and their use
in inhibiting and preventing foaming problems. More particularly,
the instant invention relates to an antifoam composition comprising
an organic-mineral clay complex which forms a stable, water
continuous emulsion or dispersion.
; Many industrial systems are particularly susceptible tofoaming problems even under mild conditions of agitation. In their
more serious aspects, these problems become a substantial drawback
in not allowing full utilization of the particular equipment
involved. Also, in many instances operating conditions are so
altered by foam that considerable interference with the process
itself is caused, with resultant low capacity and considerable
economic loss. Serious foaming sometimes occurs, for example, when
solvents or unreacted starting materials are stripped off either in
vacuo or under atmospheric conditions, leaving behind the desired
.
industrial product. Similarly, uncontrolled foaming at various
steps in a pulp and papermaking process, treatment of waste systems
and cooling towers and other industrial processes can cause
considerable difficulties.
. ~
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A brief overview of the steps and conditions involved in
pulping processes will show the need for effective foam control that
is cost-effective under a variety of conditions. At present there
are a number of different chemical pulping processes finding
extensive use in the pulp and paper industry. However, by far the
most widespread are the alkaline pulping processes commonly referred
to as the "soda" and the "kraft" processes,
~raft pulp, also referred to as sulfate pulp, represents
one type of chemical pulp. It is, perhaps, the most important of
the chemical pulps, as indicated by the large number of kraft pulp
mill installations. The reasons for the popularity of this process
are many among which can be mentioned are the strength of the
resultant pulp, the varieties of wood that lend themselves to this
process, and the excellent degree of chemical recovery of cooking
liquors which is possible.
In the kraft process, measured quantities of standard
sized chips are directed to a digester which is a heated pressured
vessel . Briefly stated, in addition to the wood chips, white
liquor (which is the cooking liquor, the active chemical ingredients
of which are caustic soda and sodium sulfide) and steam are charged
; to the digester. Through the action of the cooking liquor and steam
on the chips, the lignin binder is dissolved, freeing the cellulose
~ 25 fibers. Thus the chips are converted into a brown colored kraft
; pulp. The cooking is normally performed under pressure varying from
80 - llO psi. Although the active chemicals in the cooking liquor
(white liquor) are caustic soda and sodium sulfide, the liquor will
also contain some sodium carbonate and some sodium sulfate. The
kraft process is sometimes called "sulfate" because sodium sulfate
(saltcake) is the makeup chemical for converting the black liquor to
` white liquor.
1 ~2~n5~
During the cooking process in the digester, the white
liquor becomes black as it is spent in cooking. After the cook, the
pressure in the digester is reduced to separate the cell~lose
fibers. The fibers and black liquor may than be directed over d
knot screen and then to vacuum washers, at which point the black
liquor is separated from the pulp. The pulp is then sent to the
bleach plant, or if unbleached kraft is to be used, the pulp is
directed to the paper mill.
- 10 The pulp washing, which accomplishes the removal of the
black liquor from the pulp, is the point at which brown stock
defoamers and drainage aids are required. The washing takes place
in a group of washers connected in series and is counter current.
Weak liquor removed from the pulp on the last washer is
sprayed on the pulp on the previous washer. This continues back to
the first washer. By using this process, the pulp is always washed
by a liquor of lower solids content that the pulp itself contains.
This permits removal of solids from the pulp with minimu~ fresh
f 20 water requirements.
Although the soda and kraft processes possess distinct
advantages with respect to the rec1aiming and reuse of the spent
chemicals, the processes do possess inherent disadvantages due to
the foaming problems which are encountered at various steps in the
25 process. The most troublesome areas are at the pulp washing,
screening and knotting stages of the operation. During these stages
a considerable amount of troublesome foam is generally formed.
;~ Likewise, when the resulting pulp is being washed in the brown stock
washers to remove residual black liquor chemicals, a significant
- 30 foam problem is encountered. A black liquor contains from 13 to 20%
t 324058
by weight of dissolved solids and has a pH in the range of from
about 11 to 13. Because of the constitution of the black liquor,
that is, its resin content, its dissolved solids content and the pH
of the system, there is a definite foaming potential, which if
allowed to occur, affects the entire system deleteriously.
Foam is equally encountered after the pulp has left the
brown stock washers and has traveled to the screenroom where the
pulp is again diluted with water and passed through the various
screening operations. This operation allows the satisfactory fibers
to pass through while the clumps of unpulped fibers, knots or other
foreign material are retained on the screen. In addition, foam
becomes quite significant in the screenroom where the diluted pulp
containing a small residual amount of black liquor is subjected to
violent agitation by the screen. The black liquor removed during
the screening operation is normally used as the dilution water in
the various stages of the brown stock washers, therefore, since the
` diluted black liquor still contains a minor amount of solids, a foaming potential exists.
The foaming problems encountered at various stages of
operation are dependent upon a number of factors such as the type
wood used in the pulp making process, the conditions, e.g.
temperature and the extent of agitation, the amount and type of
undissolved solids dispersed in the liquor and the dissolved
materials in the liquor. It is ccmmon in some pulping processes to
find that foaming is not a particular problem at one stage but that
it does become a problem at a later stage as when the liquor or
effluent of one stage is returned to the system as a washing or
diluting agent at another stage of the operation.
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Since the foaming problems do have a significant effect on
the efficiency of the pulp producing process and since the economics
of the pulp producing system itself are greatly affected, many anti-
foaming and defodming compositions have been proposed for use during
the stages of operation in question.
The various antifoaming and defoamers recommended for use,
although possessing distinct advantages in some aspects, also
possess attenddnt disadvantages. For example, a formulated defoamer
or antifoaming agent may be satisfactory with one particular type
wood such as spruce or fir, but may not be at all successful in
retarding foam where the fibers are derived from hemlock. Moreover,
; it is not unusual to find differences when the same type wood is
utilized to produce a pulp. The conditions of the operation in one
instance may be such as to render a defoamer wholly inoperable while
at the same time this same defoamer may be perfectly successful in
another simi1ar process. The differences in the respective
operations can be attributed to the relative differences in
temperature, the type water used and the respective agitation and/or
aeration times utilized.
.
In addition to the paper industry, other industries suffer
from foam problems and can realize advantages from foam control; for
example, the biological treatment of waste waters. Aeration basins,
secondary clarifiers, and lagoons can suffer severe problems if foam
is not controlled. In aeration basins there are organic compounds
which may stabilize foam during aeration. If uncontrolled, this
foam can carry bacteria out of the treatment system which reduces
the efficacy of the treatment system. Also foam may be blown out of
~- 30 the basin by the wind, potentially causing a health problem, andeventually an odor problem as the bacteria decompose.
1 324058
-- 6 --
Secondary clarifiers suffer from foam problems by having
air entrained in the flocculated sludge. This results in a layer of
floc floating on the surface. If this floating floc allowed to
continue untreated the entire clarifier may become anaerobic. The
anaerobic bacteria metabolism by-products include mercaptans and
other gases which are generated at the bottom of the clarifier,
resulting in even more floating sludge and odor problems.
;
In order to counteract foaming problems of the types
discussed above and others, a chemical treatment to both abate the
existing foam and prevent its reoccurrence is often used. Water
continuous antifoam emulsions have been used in these industries for
many years. Antifoams generally contain an antifoam agent, a
carrier, an emulsifier or a stabilizing agent. The antifoam agent
is the active ingredient in the antifoam composition. The active
; ingredients commonly used in antifoam compositions are well known in
the art. These include, but are not limited to, hydrophobic
inorganic particulates, alkyl amides, silicone oil, fatty alcohols,
fatty acids, fatty esters, polyalkylene glycols, polyether
copolymers and fatty glycerides.
Water continuous emulsions and/or dispersions have
traditionally relied on hydrophilic surfactants (HLB > 8) to form a
physically stable system. These types of surfactants are typically
either nonionic or anionic in nature. Some examples of nonionic
surfactants include, but are not limited to, ethylene oxide
condensation products of alkyl phenols, fatty alcohols, and fatty
acids. Some examples of anionic surfactants include, but are not
limited to, alcohol sulfa~es and sulfonates, sulfates and sulfonates
of alkyl phenols which may also be ethoxylated, sulfates of fatty
esters and sulfonates of condensed naphthalenes.
1 324058
These surfactants, depending on the chemical type and
concentration, are known to form varying degrees of stable foam. It
is also known to those skil1ed in the art that the chemica1 type and
; concentration of surfactants used in formu1ating a particu1ar
defoaming composition has a great influence on the defoaming power
or efficacy of the active defoaming compounds. This detrimenta1
effect may be the resu1t of surfactant absorption onto the defoaming
compound thereby rendering that active hydrophilic.
The carrier usua11y comprises the bu1k of an antifoam
formu1ation~ Carriers are genera11y hydrocarbon oi1s or water
a1though other products such as solvents are sometimes used. The
carrier serves to introduce the active ingredients into the system
and may contribute to product performance.
- 15 Another important consideration is the cost involved.
Although a particular antifoamer may have successfully inhibited the
foaming potentia1 of d particu1ar system, the feed rate and the
- initial cost of antifoamers may be such as to make its use
prohibitive. Accordingly, it can be appreciated that when all of
the factors are considered, it is extreme1y difficult to formu1ate a
particu1ar composition which will not on1y perform the function
desired but which will also be operable at the specific feed rates
demanded by industry. With the foregoing in mind, the present
inventor embarked upon a study in an attempt to produce a defoamer
or antifoaming agent which would fulfill as many of the
prerequisites as possible.
1 324058
SUMMARY OF THE INVENTION
The present invention relates to a novel antifoam
composition which does not rely on hydrophilic surfactants as
stabilizers, but rather on an organic-mineral clay complex to form a
stable, water continuous emulsion or dispersion. The clay used may
be any suitable mineral clay such as montmorillonite clay or
bentonite clay. The organic part of the complex comprises a
hydroxyl functional material. The oil and water phases of the
` 10 antifoam composition are bridged by the organic-mineral clay
complex. The oil or dispersed phase of the antifoam composition
comprises d water insoluble, inert organic liquid carrier, various
defoaming active ingredients, and the hydroxyl functional material.
The composition is useful in controlling foam encountered
in preparation of paper pulp, and in the treatment of waste systems
and cooling towers.
.
DETAILED DESCRIPTION OF THE INYENTION
The present inventor discovered that a stable water
continuous emulsion could be formed using an organic-mineral clay
complex. The antifoam composition comprises oil and water phases
which are bridged by the organic-mineral clay complex.
When clay is dispersed in water it forms a structured
network; commonly referred to as a "house of cards", which yields a
viscous water phase. The organic part of the organic-clay complex
comprises a hydroxyl functional material. The hydroxyl functional
materials form the organic-clay complex which results in a bridge
1 324058
g
connecting the oil and water phases. Examples of the hydroxyl
functional materials include, but are not limited to, glycerol,
ethylene glycol, glycerol fatty esters, fatty glycerides and
mixtures thereof. Preferrably the hydroxyl functional material is a
fatty glyceride. It is anticipated that other hydroxyl functional
materials will also work.
The clay used may be any suitable mineral clay such as
montmorillonite clay or bentonite clay. A bentonite clay mixture,
sold under the trademark "Mineral Colloids 101" available from
Georgia Kaolin and Hectorite and examples of suitable types of
mineral clay.
; The oil or dispersed phase of the antifoam composition
consists of a water insoluble, inert organic liquid carrier, various
defoaming actives, and the hydroxyl functional material. Examples
of suitable, commercially useful carriers include, but are not
limited to, naphthenic mineral oil, paraffinic mineral oil, and
silicone oils, and mixtures thereof. Preferably the carrier is a
paraffinic mineral oil.
Several types of active defoaming ingredients have been
incorporated into the water insoluble carrier. Generally, an active
defoaming ingredient should be insoluble in the foaming medium and
have a surface free energy less than the foaming medium. These
actives include, but are not limited to, hydrophobic inorganic
particulates such as silica, alkyl bisamides, polyalkylene glycols,
oil soluble polymers, such as alkylmethacrylate n-vinyl pyrillodone
graft copolymer, vinyl acetate and fumeric acid esterified with
tallow alcohol, polydimethyl siloxane and polysiloxane glycol
; copolymers, polyether copolymers, fatty ketones, polyalkylene glycol
1 324058
- 10 -
esters, fatty alcohols, fatty acids, and mixtures thereof
Preferred active ingredients are hydrophobic inorganic particulates,
alkyl bisamides such as ethylene bis--stearamide (EBSl, polydimethyl
siloxanes, and polysiloxane glycol copolymers, and ethylene oxide
propylene oxide (EO:P0) copolymers.
The weight proportions of the ingredients forming the
novel antifoam composition are preferably as follows:
10 (a) hydroxyl functional material(s) 0.5% to 4~, more
preferably about 1% to 3%.
(b) organic liquid carrier 15~ to 25~, more preferably about
~8% to 23~.
15 lc) mineral clay 1~ to 5~, more preferably about 2% to 4%.
(d) antifoam active ingredient(s) 0.5% to 7%, more preferably
about 2~ to 4~.
~e) water 60~ to 80A., more preferably about 68% to 76%.
The compositions of the present invention may be made by
dispersing the mineral clay in water. The dispersed phase is
prepared by melting and/or dispersing the defoaming ingredients and
the hydroxyl functional material in the inert organic liquid
carrier. Then the dispersed phase is added to the mineral
clay/water dispersion with agitation. The resulting mixture is then
cooled with continuous agitation to yield the desired product.
Mechanical agitation is needed eO effect unifor
dispersion of t~le CompOnerltS
B
1 324058
The novel antifoam composition is utilized by adding a
small amount to the system in which control of foaming is desired.
The exact quantity required to control foam will vary depending upon
the nature of the liquid being treated, the individual antifoam
composition, and upon the amount of foam which can be tolerated in
the process Typically an amount ranging from about 0.01~ to 1.0~
by weight based upon the weight of the solids present in the foaming
system will be used.
.
The antifoam compositions of this invention were tested
for their effectiveness by the following procedure: S00
milliliters(~L) of typical pulp mill foaming stock is charged into a
glass vessel; an amount of the antifoam composition to be tested is
introduced into the vessel; a pump is used to circulate the stock
from the base of the vessel to a hose and nozzle assembly through
which a stream of the liquid is made to impinge upon the surface of
the sample in the vessel. The amount of foam generated is measured
at 15 second intervals over a test period of 180 seconds. In some
cases, the foam level reaches the top of the vessel (300 mL) in less
than 180 seconds; in these cases the elapsed time is recorded. Foam
height and/or top time is a good measure of the relative
effectiveness of the antifoam composition.
The following compositions illustrate the invention:
1 324058
. - 12 -
~:'
Composition A
. Weight
. Component Percent
';
-:~. Naphthenic Mineral Oil 18.00
-~. 5 Hydrophobic Silica 1.00
:,~ EBS 1.00
EO:PO Copolymer 1.00
Alkylmethacrylate N-vinyl
. Pyrillidone Graft Copolymer 1.00
10 Glycerol Monostearate 1.00
Water 75,00
.: Bentonite Clay 2.00
Composition B
Weight
Component Percent
20 Paraffinic Mineral Oil 18.00
i; EBS 2.00
~: EO:PO Copolymer 1.00
Glycerol Monostearate 1.00
, Water 76.00
. 25 Bentonite Clay 2.00
:~
i Composition C
-~ Weight
~ 30 Component Percent
i:
Paraffinic Mineral Oil 23.00
` EBS 1.00
Silicone Glycol Copolymer 0.25
35 Glycerol Monostearate 0.60
Water 71.15
Bentonite Clay 4.00
.~.
~i
~.
.,
r
` 1 324058
~.
. - 13 -
Composition D
, Weight
. Com~onent Percent
~- 5 Paraffinic Mineral Oil 23,00
EBS 2.00
Glycerol Monostearate 2.40
. Water 68.60
: Bentonite Clay 4.00
-i ~
-~. 10 Composition E
; Weight
,............. Component Percent
15 Paraffinic Mineral Oil 23.00
~. EBS
;~ Glycerol Monostearate 2.00
Water 69.00
p Bentonite Clay 3.00
~:
Composition F
. Weight
. Component Percent
~' 25 Paraffinic Mineral Oil 20.00
.~ Hydrophobic Silica 1.00
EBS 1.00
Silicone Glycol Copolymer 0.25
~ Alkylmethacrylate N-vinyl
:~, 30 Pyrillidone Graft Copolymer 1.00
.; Glycerol Monostearate 1.00
~: Water 71.75
Bentonite Clay 4.00
`~
,
,~
's
~s~
.~
~:
. 1 324058
...
- 14 -
Composition G
Weight
Component Percent
,
A~ 5 Paraffinic Mineral Oil 23.00
Hydrophobic Silica 3.00
~ EBS 3~0
r Alkylmethacrylate N-vinyl
Pyrillidone Graft Copolymer 1.00
10 Glycerol Monostearate 2.00
Water 63.00
Bentonite Clay 5.00
The compositions prepared according to the above
specifications were tested for their antifoaming ability using the
~; test procedures described above. The compositions were tested on
~-~; three different samples of pulp mill stock. The novel compositions
were tested against three typical, commercially available antifoam
compositions designated H, I, J, K, and L. Commercial Compositions
~ 20 I and K contain emulsified EBS in oil and are water based antifoams
-~s utilizing hydrophillic surfactants. Commercial Compositions H and J
are water based antifoams utilizing hydrophillic surfactants
containing fatty alcohols. Commercial Composition L is a water
extended antifoam (i.e., water in oil emulsion) containing emulsifed
.
~ 25 EBS in oil.
,
Table l reports the results using a dilute black liquor
containing lX solids at 120 F.
.
'~
..
'~'
,~j,
~,
t
~ 1 324058
- 15 -
Table 1
1~ BLACK LIQUOR
SOLIDS AT 120F
Height at
Dosage Top Time 200 sec
Example Antifoam (ul) (sec) (mm)
`s
.
1 None 0 7
.: 2 Commercial Composition H 10 120
s 3 20 150
4 30 200 275
200 270
6 50 200 225
7 Commercial Composition I 10 149
8 20 200 255
~ 9 30 200 245
:.~ 20 10 40 200 230
~:~ 11 50 200 195
;:~ 12 Commercial Composition J 10 52-~`. 13 20 74
14 30 141
167
16 50 171
r.~ 17 Composition A 10 130
. . 30 18 20 200 270
. 19 30 200 205
. ~. 20 40 200 200
~: 21 50 200 175
.~,
~- 35 22 Composition B 10 129
:~ 23 20 147
24 30 156
. : 25 40 200 220
: 26 50 200 180
;~`
.''~;
..,~.
'"~
'~
1 324058
!
- 1 6 -
The lX test solution represents a typically clean pulp
mill screen room application. Compared to the typica1 examples of
commercially available antifoams, the inventive antifoam
compositions showed defoaming activity which generally lasted longer.
~, 5 The top time is a measure of how long it takes the foam to reach the
,~ top of the glass vessel. The length of time necessary for the foam
to reach the top of the vessel is an indication of the effectiveness
~;~ of the antifoam composition. The height of the foam at 200 seconds
~ (3 minutes) is also an indication of the effectiveness of the
r~ 10 antifoam composition.
;
Composition A exhibited a foam height of 175 mm in
Example 21 after 200 seconds whereas the closest commercial
composition in Example 11 was 20 mm higher under the same conditions.
.
:`~
Table 2 reports the results using a dilute black liquor
~' containing SX solids at 150 F.
Table 2
l l
, 20 5X BLACK LIQUOR
SOLIDS AT 150F
Height at
DosageTop Time 200 sec
Example Antifoam (ul~ (sec) (mm)
27 None 0 7
28 Commercial Composit~on H 10 11
2g 20 13
19
31 40 45
32 50 48
..
.~
.
.,
1 324058
- 17 -
.
. Table 2 (continued)
Height at
: Dosage Top Time 200 sec
5 Example Antifoam (ul~ (sec) (mm)
.. 33 Commercial Composition I 10 19
: 34 20 37
' 5 35 30 75
36 40 105
38 60 168
~; 39 80 200 295
.: 10 40 100 200 285
.
.~
41 Commercial Composition J 10 7
,.~ 42 20 7
43 30 9
44 40 11
16
46 Composition A 10 114
~ 47 20
48 30 200 285
~' 49 40 200 260
200 245
bi 51 Composition B 10 12
.~ ;~ 25 52 20
. . 53 30 63
54 40
~; 55 50 125
56 70 200 220
~: 30 57 80 200 220
~.
`~ The 5% test solution represents a particularly dirty pulp
$ mill screen room operating at a higher temperature. The inventive
`~ 35 anti-foam compositions show significantly better defoaming
performance than the commercial antifoams at higher temperature and
solids conditions.
;
.,
.
. .
,
.
1 324058
- 18 -
Following the procedure described above, the following
results were obtained.
. 5TABLE III
~ ..
` 3% BLACK LIQUOR SOLIDS AT 150F
,? Helght at
-' 10 Dosage Top Time 200 sec
Example Antifoam (ul~ (sec) (mm)
58 Commercial Composition I 50 -- 300
59 Composition C 50 -- 230
i 15 60 Composition F 50 -- 250
,.
!).~ .
A 3% test solution represents a moderately dirty pulp mill
~; screen room operatlng at a higher temperature. The results in Table
: ~ III lllustrate the effectiveness of the present invention in
controlling foaming.
.~
Other composltions of the present invention were tested as
described above. The results are shown in Table IV.
. .
TABLE IV
5X BLACK LIQUOR SOLIDS AT 150F
..
. .
Height at
- Dosage Top Time 200 sec
Example Antifoam (ul) (sec) (mm)
61 Commerclal CGmposltlon I 50 60 ---
35 62 Commerlcal Composltlon K 50 90 ---
63 Commerical Composltlon L 50 -- 290
64 Composition A 50 -- 245
~,
.
' . . .
.,,
1 324058
';
.~
, , g
' Height at
i DosageTop Time 200 sec
. Example Antifoam (ul) (sec) (mm)
^~ 5 65 Composition B50 125 ---
': 66 Composition C 50 --- 290
, 67 Composition D 50 --- 205
68 Composition E 50 --- 285
69 Composition F 50 105 ---
70 Composition G50 95 ---
The water based commerical compositions were not as
-~ effective at controlling foam as were the water based inventive compositions.
While this invention has been described with respect to
$~ particular embodiments thereof, it is apparent that numerous other
forms and modifications of this invention will be obvious to those
skilled in the art. The appended claims and this invention
~ generally should be construed to cover all such obvious forms and
s, 20 modifications which are within the true spirit and scope of the
present invention.
1:
~,
