Note: Descriptions are shown in the official language in which they were submitted.
DESCRIPTION
DEWATERING AGENT FOR SLUDGE
Technical Field
The present invention relates to a novel process
for preparing an acrylic polymer having a free tertiary
amino group which is not quaternized or not salt formed
and having a high molecular weight, which has been
10 conventionally difficult to be prepared, and a dewatering
agent for sludge using the same.
Background Art
Generally, a dewatering agent for sludge, which
shows excellent flocculating ability and dewatering
ability in a small amount and which is able to be burned
up, has been widely used as a flocculant and a dewatering
a~ nt against sewage sludge, industrial drainage
sludge, and the like.
When an acrylic monomer containing a tertiary
amino group is polymerized as it is, since its
polymerization does not proceed and a molecular weight
does not increase, generally, polymerization has been
carried out after the tertiary amino group is quaternized
25 with an alkyl halide and the like or the acrylic monomer
is salt formed with a mineral acid and the like.
For instance, as a dewatering agent for sludge,
a water-soluble vinyl polymer having a quaternary ammonium
group or a tertiary ammonium salt neutralized with a
30 mineral acid and the like has been used. For instance,
polymers having an ~mmonium group quaternized with an
alkyl halide such as methyl chloride or ethyl chloride,
dimethyl sulfate, diethyl sulfate, and the like are
described in J~r~nesP F.~min~(~ Patent Publication No.
52040/1990, JapaneseF~c~mine~l Patent Publication No.
51141/1988, JapaneseFx~min~d Patent Publication No.
48863/1988, JapaneseFx~minPr~ Patent Publication No.
15491/1983, JapaneseUnP~mine-l Patent Publication No.
-
133670/1982, and the like, and a polymer having an
ammonium group quaternized with benzyl chloride is
described in Japanese Un~ min~d Patent Publication No.
51899/1982 and the like. Also, in Japanese ~x~minecl
Patent Publication No. 52040/1990, Japanese F~minecl
Patent Publication No. 15491/1983, Japanese Un~minefl
Patent Publication No. 49410/1983, Japanese Une~r~mined
Patent Publication No. 47005/1983, Japanese Un~x~minecl
Patent Publication No. 133670/1982, and the like, polymers
10 prepared by polymerizing monomers which have been
previously salt formed by using a mineral acid such as
hydrochloric acid, sulfuric acid or phosphoric acid, or
acetic acid are described. However, because the effects
of water-soluble vinyl polymers having a quaternary
15 ammonium group or an ammonium group neutralized with a
mineral acid and the like are not sufficient for sludge
having a difficulty to flocculate and dewater, sludge
having a difficulty to flocculate and dewater has been
increased in accordance with the high improvement of the
20 treatment for waste water and the like. Then, as a
flocculant having excellent dewatering property, which can
deal with this increase of sludge, or a flocculant having
stable abilities against the change of sludge for the
purpose of simplification of working conservation, for
25 instance, it is reported in Japanese Un~ min~ocl Patent
Publication No. 189400/1989 that a basic substance is
aclded to a cationic polymer whose tertiary amino group is
salt formed, and a dewatering agent for sludge made
thereof acts as a polymer substantially containing a
30 tertiary amino group. However, a material made by adding
a basic substance to a cationic polymer whose tertiary
an!lino group is salt formed does not always show the
effects as a polymer cont~ining a tertiary amino group.
Moreover, when the neutralization of the material is
35 completely carried out with a basic substance, since the
material is changed into a dilute solution of 0.2 - % by
weight, there was a problem in practicality from the
viewpoints of transport, h~n-llin~ and the like.
Disclosure of Invention
In order- to develop a dewatering agent for
sludge which is excellent in dewatering property against
sludge and able to deal with any forms such as powder,
5 aqueous solution and emulsion, the present inventors have
earnestly studied in consideration. As a result, by making
use of a tertiary ammonium carbonate, a synthesizing
method of an acrylic polymer having a tertiary amino group
and a high molecular weight, which has been conventionally
10 difficult to be prepared, has been est~hlisbe(l, and it
has been found that the acrylic polymer can be used as a
dewatering agent for sludge showing high abilities, then
the present invention has been accompli.she-l.
That is, the present invention relates to a
15 process for preparing an acrylic polymer containing a
tertiary amino group characterizecl by containing the steps
of
reacting an aqueous solution of an acrylic monomer
containing a tertiary amino group, represented by the
20 general formula (1) with carbonic acid gas to generate an
acrylic monomer containing a tertiary ~mmonium carbonate,
represented by the general formula (2),
polymerizing the obtained monomer alone or with the other
vinyl monomer copolymerizable with the obtained monomer to
25 give a polymer cont~ining a structural unit of a tertiary
~mmo~ium c~ l,onate represented by the general formula (4),
an.d
decarboxylating the polymer with heating and/or reducing
the pressure to give a polymer containing a structural
30 un,it of a tertiary amino group represented by the general
fo:rmula (3) and having a high molecular weight.
Furthermore, the polymer cont~ining a tertiary
amino group and having a high molecular weight, which is
obtained by the above-mentioned method, shows stable
35 flocculating property and excellent dewatering property
against sludge in a small addition, and especially, an
article containing a water-soluble vinyl polymer which
co:ntains at least 5 % by mole of a structural unit
h i ~
-- 4 -- ::
represented by the general formula (3) and whose intrinsic
viscosity [ ~7 ] is at least 1 dl/g is suitable as a
dewatering agent for sludge, and the present invention
also relates to a dewatering agent for sludge.
R, / R2
CH2 = C-C0-A- (CH2)n~N (1)
\ R3
wherein R~ is hydrogen or methyl group, R2 and R3 are
lower alkyl groups of Cl-C4, n is an integer of 2-4, -A- :
is -~ or -NH-. ~:
. :
R, /R2 ~ -
CH2 = C~CO~A~(CH2)n~N+H l/2CO32- (2)
R3
wherein R1 is hydrogen or methyl group, R2 and R3 are
lower alkyl groups of Cl-c4, n is an integer of 2-4, -A- ~:
is -~ or -NH-.
2 0 R,
-CH2-C- / R2
O = C~A~(CH2)n~N\ (3)
R3
25 wherein R1 is hydrogen atom or methyl group, R2 and R3 are
alkyl groups of C1-C4, n is an integer of 2-4, -A- is -
~or -NH-.
R~
-CH2-C- / R2
O = C~A~(CH2)n~N+H l/~CO32- (4)
R3
w:herein Rl is hydrogen atom or methyl group, R2 and R3 are
35 alkyl groups of Cl-C4, n is an integer of 2-4, -A- is -
~or -NH-.
As the acrylic monomer represented by the
general formula ( 1) used in the present invention,
, ,:
.
N, N-dimethylaminopropyl(meth)acrylamide,
N, N-diethylaminopropyl(meth)acrylamide,
N, N-dimethylaminobutyl(meth)acrylamide,
N, N-diethylaminobutyl(meth)acrylamide,
5 N, N-dimethylaminoethyl (meth)acrylate,
N, N-diethylaminoethyl (meth)acrylate,
N, N-methylethylaminopropyl(meth)acrylamide,
N, N-methylethylaminoethyl (meth)acrylate, and the like are
.o~emplified.
Also, the acrylic monomer containing a tertiary
am~Tlonium carbonate, represented by the general formula
(2) is synthesized by reacting ani aqueous solution of an
acrylic monomer containing a tertiary amino group,
represented by the general formula ( 1) with carbonic acid
15 gas under ordinary pressure or under pressure, preferably
under pressure. At that time, it is preferable that the
reaction temperature is low because solubility of carbonic
acid gas is heightened. Concretely, it is preferable that
the reaction temperature is at most 20~C. Also, in order
20 to prevent the acrylic monomer containing a tertiary amino
group from polymerizing during its reaction, it is desired
that the system is shielded from light and a
polymerization inhibitor is added to the system.
By a known radical polymerization treatment, the
25 obtained acrylic monomer containing a tertiary ammonium
carbonate can be easily polymerized alone or with the
ot:her vinyl monomer copolymerizable with the obtained
acrylic monomer to prepare a water-soluUe polymer
containing a structural unit represented by the general
30 formula (4).
Also, as the vinyl monomer copolymerizable with
the above-mentioned monomer repr~slonted by the general
formula (2~, there is no particular limitation, and
for instance, a quaternized salt and a neutralized salt of
35 the acrylic monomer represented by the general formula
( 1), (meth)acrylamide, N-isopropylacrylamide,
N methylacrylamide, dimethylamino(meth)acrylamide, various
(meth)acrylates, (meth)acrylic acid, acrylonitrile, and
1 4
-- 6
,' ':
the like are exemplified.
By decarboxylating the obtained polymer having a
structural unit of carbonate represented by the general
formula (4) under the pressure of at most 1 atom at the
5 temperature of from ordinary temperature to 100~C, the
structural unit of carbonate can be changed to a tertiary
amino group, so that a water-soluble polymer containing a
structural unit of a free tertiary amino group represented
by the general formula (3) can be obtained. -~
For instance, when the thus obtained acrylic :
polymer containing a tertiary amino group is used in a
dewatering a~ nt for sludge as a flocculant, the
acrylic polymer shows characteristics, which have not been
conventionally known such that the obtained acrylic
15 polymer shows a higher dewatering percentage in comparison
with a conventionally used quaternary salt type or
tertiary salt type cationic polymer, and shows stable
abilities in a wide range of the amount added, that the
most suitable amount added of the obtained acrylic polymer
20 is less than that of a conventional vinyl polymer
containing a strong anion as a counter ion, and that the
obtained acrylic polymer has .o~c~ nt peeling property of
a cake from a filter cloth.
At this time, when the structural unit
25 represented by the above-mentioned general formula (3)
and/or the general formula (4) contained in the polymer
is less than 5 % by mole, since ,o~c~ nt flocculating
ability is not sufficient, it is preferable that at least
5 % by mole of the structural unit is contained, and in
30 order to stably reveal ~c.oll~nt abilities, it is
preferable that at least 10 % by mole of the structural
unit is contained. Also, when the intrinsic viscosity
[ 7~ ] of the polymer is less than 1, since sufficient
flocculating ability is not obtained, it is preferable
35 that the intrinsic viscosity [ 7~ ] is at least 1.
Best Mode for Carrying out the Invention -
The present invention is specifically explained
by means of the following Examples.
In Examples and Comparative Examples described
below, flocculating ability was evaluated in accordance
with the following criteria and its results were shown in
5 Table 1 or Table 2.
Using city sewage digested sludge having solid
matter of 1. 0 % by weight and pH of 7. 3, after each 0. 2 %
by weight aqueous solution of the polymer obtained in
Examples 2-9 and Comparative Examples 1-4 was added to the
city sewage digested sludge so that the amount of the
polymer was 0. 3-2. 0 % by weight based upon the solid
matter, and they were stirred at 200 rpm for 30 seconds by
means of a jar tester, the dewatering rate of the sludge
measured by means of a CST (capillary suction time)
evaluation apparatus is shown in Table 1, and also, the
moisture content of the cake and the peeling property
of the cake from a filter cloth measured by means of a
simplified belt press dewatering apparatus were shown in
Table 2.
At this time, with respect to the evaluation of
the peeling property of the cake from the filter cloth, a
mark of O means that the cake did not adhere to the
filter cloth, a mark of ~ means that the cake slightly
aclhered to the filter cloth and a mark of x means that
25 ~he cake considerably adhered to the filter cloth.
~le 1 (Synthesis of carbonate monomer)
To a lL glass autoclave equipped with a
th.ermometer, a pressure gauge and a tube for introducing
30 carbonic acid gas, 281.2 g ! of
N, N-dimethylaminopropylacrylamide (hereinafter referred to
as DMAPAA), 240.8 g of pure water and 0.7 g of
p--methoxyphenol as a polymerization inhibitor were added,
an.d carbonic acid gas was provided thereto with stirring
35 at 0~C under a pressure of 2 kg/cm2 in a shielded state
from light. After reacted for 24 hours, 563 g of 60 % by
weight aqueous solution of DMAPAA ca~ e was obtained
From the change of weight between before and after the
reaction (522.7 g ~ 563.0 g) and the change of pH of
reaction solution from pH 13 to pH 8, it is judged that
the DMAPAA carbonate was produced.
Example 2
To 60 g of 60 % by weight aqueous solution of
DMAPAA carbonate, 0.03 % by weight of benzyl dimethyl
ketal and 0. 01 % by weight of EDTA-2Na were added. The
obtained mixture was added to a 500 ml three-necked
separable flask equipped with a temperature sensor, a tube
for introducing gas and an exhaust pipe. While carbonic
ac id gas was flowed into the flask, light was irradiated
thereto from the bottom of the flask using a low-pressure
mercury lamp of 1 w/m2 strength until the polymerization
temperature attained to its peak.
Next, the polymerization was carried out by
irradiating light by means of a high-pressure mercury lamp
of 50 w/mZ strength for 3 minutes to give DMAPAA carbonate
polymer. When the intrinsic viscosity ~ 71 ] of a lN NaCl
20 aqueous solution of the obtained polymer was measured at
25~C, it was 3.7 (dl/g). Also, the flocculating ability
was evaluated. The results were shown in Table 1 and
Table 2.
2 S Example 3
The polymer obtained in Example 2 was
decarboxylated at 40~C to give DMAPAA polymer having a
tertiary amino group. When the intrinsic viscosity [ 77 ]
of a lN NaCl aqueous solution of the obtained polymer was
30 measured at 25~C, it was 3. 6 (dl/g). Also, the
flocculating ability was evaluated. The results were
sh,own in Table 1 and Table 2.
Example 4
The treatment of the polymerization was carried
OUIt in the same manner as in Example 2 except that berLzyl
dimethyl ketal was changed to 0.10 % by weight and
EDTA-2Na was changed to 0.03 % by weight in the conditions
~ .
of Example 2, and then, decarboxylation was carried out in
the same manner as in Example 3 to give DMAPAA polymer.
When the intrinsic viscosity [ 71 ] of a lN NaCl aqueous
solution of the obtained polymer was measured at 25~C, it
5 was 1. 2 (dl/g). Also, the flocculating ability was
evaluated. The results were shown in Table 1 and Table 2.
Example 5
To 11 g of 60 % by weight aqueous solution of
10 DMAPAA carbonate, 36.8 g of 80 % by weight aqueous
solution of N, N-dimethylaminoethyl methacrylate methyl
chloride quaternary ~mmonium salt (hereinafter referred to
as DM-C) (DMAPAA carbonate: DM-C=2: 8 (molar ratio)) and
12. 2 g of pure water were added, and the polymerization
15 was carried out in the same manner as in F.x~mple 2, and
decarboxylation was carried out in the same manner as in
E~cample 3 to give DMAPM/DM-C copolymer polymer. When
DM-C in the obtained polymer was analyzed by means of a
quaternary ammonium salt measuring method, the quaternary
20 ammonium salt value was 84 %, and thereby the molar ratio
of DMAPAA: DM-C of the present polymer was calculated to
about 2:8. Also, when the intrinsic viscosity [ ~7 ] of a
lN Naa aqueous solution of the present polymer was
measured at 25~C, it was 4.5 (dl/g). Also, the
25 flocculating ability was evaluated. The results were
shown in Table 1 and Table 2.
Examle 6
To 41.2 g of 60 % by weight aqueous solution of
30 DMAPM carbonate, 18.8 g of 50 % by weight aqueous
solution of acrylamide (hereinarler referred to as AAm)
(DMAPM carbonate: AAm=l: 1 molar ratio) was added, the
polymerization was carried out in the same manner as in
F.~mple 2, and decarboxylation was carried out in the same
35 manner as in Example 3 to give DMAPAA/AAm copolymer
polymer. The present polymer was analyzed by colloidal
titration, and as a result, the degree of cationization
was 69 % and the molar ratio of DMAPAA:Mm was about
-- 10
1:1. When the intrinsic viscosity [ 77 ] of a lN NaC1
aqueous solution of the obtained polymer was measured at
25~C, it was 6.7 (dl/g). Also, the flocculating ability
was evaluated. The results were shown in Table 1 and
5 Table 2.
Example 7
Twenty six g of 60 % by weight aqueous solution
of DMAPAA polymer obtained in F.~mple 3 and 14.2 g of 50 %
10 by weight aqueous solution of acrylamide polymer whose
[ ~7 ] was 9.7 (dl/g) were blended with stirring (DMAPAA
poiymer: AAm polymer=1: 1 (molar ratio)). Also, the
flocculating ability was evaluated. The results were
shown in Table 1 and Table 2.
Example 8
Sixty g of 60 % by weight aqueous solution of
N, N-dimethylaminopropyl(meth)acrylamide carbonate
(hereinafter referred to as DMAPMA carbonate) was
20 polymerized in the same manner as in F~mI~le 2 and treated
in the same manner as in Example 3 to give DMAPMA polymer.
When the intrinsic viscosity [ 77 ] of a lN NaCl aqueous
solution of the obtained polymer was measured at 25~C, it
was 3.4 (dl/g). Also, the flocculating ability was
25 evaluated. The results were shown in Table 1 and Table 2.
F~mr)le 9
Sixty g of 60 % by weight aqueous solution of
N, N-dimethylaminoethylacrylamide carbonate (hereinafter
30 referred to as DMAEAA carbonate) was polymerized in the
same manner as in Example 2 and treated in the same manner
as in li~mple 3 to give DMAEAA polymer. When the
intrinsic viscosity [ 7~ ] of a lN NaCl aqueous solution of
the obtained polymer was measured at 25~C, it was 3.5
35 (dl/g). Also, the flocculating ability was evaluated.
The results were shown in Table 1 and Table 2.
.,~ :
h i ~
.
-- 11 --
Comparative Example 1
To a 500 ml three-necked separable flask
equipped with a temperature sensor, a tube for introducing
gas and an exhaust pipe, 60 g of 60 % by weight aqueous
5 solution of DMAPAA was added. Light was irradiated
thereto from the bottom of the flask by means of a
low-pressure mercury lamp of 1 w/m2 strength while
carbonic acid gas was flowed thereto, Then, the
polymerization was carried out by irradiating light by
10 means of a high-pressure mercury lamp of 50 w/m2 strength
for 3 minutes. The content was in starch syrup-like state
having fluidity. When the intrinsic viscosity [ 77 ] of a
lN NaCl aqueous solution of the obtained polymer was
measured at 25~C, it was 0.01 (dl/g). Also, the
15 flocculating ability was evaluated. The results were
shown in Table 1 and Table 2.
Comparative Examples 2-4
The polymerization was carried out in the same
20 manner as in Example 2 to give polymers except that each
of 60 g of 50 % by weight aqueous solution of DMAPAA
sulfate, 60 g of 50 % by weight aqueous solution of N,N-
dimethylaminoethyl acrylate methyl chloride quaternary
salt (hereinafter referred to as DMAEA-Q) and 60 g of 50 %
25 by weight aqueous solution of DM-C was used instead of
D~ IAPAA carbonate in F,~mI~le 2. When each intrinsic
viscosity [ 77 ] of lN NaCl aqueous solutions of the
obtained polymers was measured at 25~C, the intrinsic
viscosity of DMAPAA sulfate polymer was 4.1, that of
30 D~IAEA-Q polymer was 8.3 and that of DM-C polymer solution
W;lS 7.7 (dl/c). A1SOI the flocculating ability was
evaluated. The results were shown in Table 1 and Table 2.
Example 10
3 5 (Polymerization, and synthesis of a polymer conataining a
tertiary amino group)
To a 500 ml three-necked separable flask
equipped with a thermometer, a tube for introducing gas
... - . ... .... ~ ~
-- 12 -
and an exhaust pipe, 100 g of 60 % by weight aqueous
solution of DMAPAA carbonate obtained in the same manner
as in Example 1 was added. While carbonic acid gas was
bubbled to the flask in a constant temperature bath of
5 20~C, 0.6 ml of 1 % by weight aqueous solution of
2,2-azobis[ 2-(2-imidazolin-2-yl)propane] dihydrochloride
as a polymerization initiator was added to the flask, and
the polymerization was carried out. A free DMAPAA polymer
having a tertiary amino group was obtained by drying under
10 a pressure of 50 mmHg at 40~C for 12 hours and
decarboxylating the obtained aqueous polymer solution.
When the intrinsic viscosity [ ~7 ] of a lN NaCl aqueous
solution of the polymer was measured at 25~C, it was 5. 2
dl/g.
F~mple 1 1
To 91.3 g of 60 % by weigh~ aqueous solution of
DMAPM carbonate obtained in the same manner as in Example
(synthesis of carbonate), 5. 2 g of acrylamide (DMAPM
20 carbonate: acrylamide=8:2 molar ratio) and 3.5 g of pure
water were added. The polymerization, and decarboxylating
and drying were carried out in the same manner as in
Examples 1-2 (polymerization, and synthesis of a polymer
cont~ining a tertiary amino group) to give a copolymer
25 polymer. When the intrinsic viscosity of a lN NaCl aqueous
solution of the obtained polymer was measured at 25~C, it
was 6. 1.
Fx~mple 1 2
(Synthesis of carbonate)
To a lL glass autoclave equipped with a
thermometer, a pressure gauge and a tube for introducing
carbonic acid gas, 282.6 g of N,N-dimethylaminoethyl
methacrylate (hereinafter referred to as DMAEMA), 242.2g
3 5 of pure water and 0. 7 g of p-methoxyphenol were added, and
carbonic acid gas was provided thereto with stirring at
0~C under a pressure of 2 kg/cm2 in a shielded state from
light. After reacted for 24 hours, 565 g of 60 % by
-- 13
weight aqueous solution of DMAEMA carbonate was obtained.
To a 500 ml three-necked separable flask equipped with a
thermometer, a tube for introducing gas and an exhaust
pipe, 100 g of the obtained 60 % by weight aqueous
5 solution of DMAEMA carbonate was added. While carbonic
acid gas was bubbled to the flask in a constant
temperature bath of 20~C, 0.6 ml of 1 % by weight aqueous
solution of 2, 2-azobis[ 2-t2-imidazolin-2-yl)-propane]
dihydrochloride was added to the flask, and the
10 polymerization was carried out. A free DMAEMA polymer
having a tertiary amino group was obtained by drying under
a pressure of 50 mmHg at 40~C for 12 hours and
decarboxylating the obtained aqueous polymer solution.
When the intrinsic viscosity [ 77 ] of a lN NaCl aqueous
15 solution of the polymer was measured at 25~C, it was 5.8.
From the results shown in Table 1, flocculating
and dewatering ability of a conventional acrylic polymer
having a strong anion as a counter ion was sharply lowered
ar-ound the most suitable amount thereof added to the
20 sludge. On the contrary, the acrylic polymer containing a
tertiary amino group synthesized by homopolymerization or
copolymerization according to the present invention showed
high dewatering percentage and stable ability in a wide
range of the amount added of the polymer. Also, the most
25 suitable amount added of the polymer was less than that of
the conventional acrylic polymer having a strong anion as
a counter ion, and the peeling property of the cake from a
filter cloth was ~o~c.ollent.
Industrial Applicability
An acrylic polymer containing a free tertiary
amino group, obtained by the present invention has a high
molecular weight, and when the acrylic polymer is used as
a dewatering agent for sludge, the dewatering agent for
sludge of the acrylic polymer cont~ining a free tertiary
amino group is effective in a smaller amount added in
comparison with a conventional dewatering agent for sludge
of an acrylic polymer containing a strong anionic counter
14
ion, and shows excellent abilities such that abilities are
stable against the change of the concentration of the
sludge and that high dewatering percentage is exhibited,
so that it is expected that the dewatering agent can
5 greatly lower the cost of treatment for sludge.
Accordingly, the dewatering agent for sludge provided by
the present invention shows ~ ont availability for
sludge having a difficulty to dewater or the like, which
is generated in water treatment places of large cities.
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