Note: Descriptions are shown in the official language in which they were submitted.
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Preparation of ~ulverulent_polymers and their use
U.S. Patent 4,135,043 discloses a process for the
preparation of pulverulent water-soluble polymers, in
which water-soluble ethylenically unsaturated monQmers
are polymerized in a powder bed in the presence of con-
vent;onal polymer;zat;on ;n;t;ators and water as an
auxil;ary liquid, wh;le maintain;ng the powder state,
conduct;ng away the heat of polymerizat;on by distill;ng
off water, and circulat;ng the reaction material.
European Laid-Open Applicat;on 27~936 likewise
d;scloses a process for the preparat;on of pulverulent
polymers by polymer;zat;on of the monomers in a po~der bed,
;n which the heat of polymerization is conducted away
us;ng inert organic solvents which act as a precipitating
agent for the polymers. The conventional processes give
polymers which have a relatively high molecular weight
and a relatively broad molecular weight distribution.
~ .S. Patent 3,898,037 discloses copolymers of
acrylamidoalkylsulfon;c or methacrylam;doalkylsulfon;c
ZO acids and acrylic acid or methacrylic acid, these copoly-
mers being used in small amounts (not more than about 100
ppm~ as corrosion inhibitors. The copolymers can be pre-
pared by copolymerization of the monomer mixture in a
solvent mixture comprising water and isopropanol.
German Patent Z,757,329 d;scloses a process for
the preparation of polymers of acrylic acid or methacrylic
acid or their mixtures~ ~n wh;ch the monomers are poly-
merized in isopropanol, or a mixture of water with not less
than 40X by ~eight, based on the mixture, of ;sopropanol,
using a free-radical polymerization ;nitiator at from 120
to 200C under superatmospheric pressure. The polymers
arè used as dispersants ~or the preparation of aqueous
pigment SUSpensiQnS for coating compositions for paper.
However~ there is also a need for pulverulent dispersants
and milling assistants, bu~ pul~erulen~ products cannot be
obtained in an economical manner by the conventional
~L2~ 7
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processes.
Although the polymers disc~osed in German Patent
Z,757,329 are very effective dispersants, they are
less useful as mi~Ling assistants for the pr~paration of
aqueous pigment suspens;ons, because m;lling is carried
out ;n a temperature range ;n ~h;ch the viscosity of the
pigment suspens;ons is very low compared w1th that at
room temperature, so that the result;ng shear;ng forces
are not as high as ;s actually des;red for the m;ll;ng
~0 process in order to comminute and to d;sperse the m;ll
base.
It ;s an object of the present invention to pro-
vide a process for the preparat;on of low molecular
we;ght, water-soluble, pulverulent polymers wh;ch can be
used, for example, as m;lling assistants and dispersants
or as encrustat;on ;nhib;tors for detergents.
~ e ha~e found that ~his object is achieved, in
accordance with the invention, by a process for the pre-
paration of pulverulent polymers based on ~ater-soluble
ethylenically unsaturated monomers by polymerization of
monomers or monomer mixtures consisting of
a) from 1ûO to 40X by weight of acry~ic acid and
or methacrylic acid,
b~ from 0 to 60X by weight of a compound of the
Z5 formula
cH2~ c-~:o-x-A-so3Me t I )
~here R ;s H or CH3, X is -NH- or -0-, A is C1-C8-alkYlene
or unsubstituted or C1-C3 a~`ky~subst;tuted alkylene and Me is
H, Na, K or N~4, and from 0 to 30X by we;ght of a compound
- of the formula
cHz=cH-so3Me tII)
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36554
where Me has the mean;ngs given ;n formula I, and
c) from 0 to 30% by we;ght of male;c anhydride or
maLeic acid, the sum of the percentages a), b) and c)
be;ng 100 in each case, and the monomers be;ng d;ssolved
S ;n water or in a water/isopropanol mixture,
in a powder bed in the presence of a conventional poly-
mer;zation in;t;ator, while ma;nta;n;ng the powder state,
conduct;ng away the heat of polymerizat;on by dist;Lling
off the solventf and c;rculat;ng the react;on material,
~f from 40 to 95X of the acidic groups of the monomers
are neutraLized and ;f the polymerization ;s ~arried out
in the presence of from ~.05 to 10 mole%, based on the
monomers, of a thiocarboxylic acid, of an enol-ether of
the formula
C~-OR (I$I)
where R ;s C1-C5-alkyl, and/or of salts or chelates
of transition metals of sub-group 8 of the per;odic
table, and of copper or 2-mercaptoethanol as a regulator.
The polymers thus prepared are ~ead;ly soluble ;n ~a~er.
They are effective mil~ing assistants and dispersants for
p;gments, and are furthermore used as encrustation
inhib;tors for detergents.
The process accord;ng to the ;nventlon g;ves
homopolymers or copolymers. For the preparat;on of the
- former~ either acryl;c acid or methacryl;c acid is sub-
jected to ~he polymer;zat;on. Copolymers are obta;ned
30 e;ther by polymerizing a mixture of acryl;c acid and
methacryl;c ac;d, or by copolymerizing one or more com-
poun~s a) w;th a compound b) and~or a compound c).
; The monomers of group b) can be represented by
the general formula I:
CH2,c-co-~-A-503~e ~ (I) or
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36554
cH2=cH-so3Me ~II)
where R ;s H or CH3, X ;s -NH- or -0-, A ;s C1-G8-alky-
lene or unsubstituted or C1-C3-~lkyL subst;tuted alkylene ànd Me
is H, Na, K, NH4 or amine.
Compounds of this type are avaiLable commercially.
Those compounds of the formula I ;n wh;ch X ;s oxygen are
prepared, for example, by rèacting a sultone, such as
propanesultone or butanesultone, with potass;um meth-
acrylate or acrylate.
A preferably used monomer of group b) ;s the com-
pound of the formuLa IV
~H3 . ~2-acrylamido-2-methyl-
c~2=C~-co-NH-c-c~2-so3H tIV) propanesulfonic acid),
1 5 CH3
CH3 ~H3 ~2-methacrylamido-
CHz=l~-CO-NH-C~-C~12-503H
(Y) propanesulfonic acid),
.
CH3 tZ-acrylamidopropane-
CH~=CH-Co-NH-C~-~H2-503H ~VI~ sulfonic acid~, or
sodium ~inylsulfonate.
The copolymers contain from 0 to 60, preferably
from 5 to 45, Z by we;ght of the monomers of the formula
I of group b),~ and from 0 to 3û~ preferably from 5 to 25,
X by weight of the monomers of the formula II.
Maleic anhydr;de or male;c acid ls used as the
monomer of group c). These monomers can be present in
the copolymers in amounts of from 0 to 30, preferably
from 0 to 20, X by weight.
Preferably, homopolymers of acry~ic acid or
copoLymers of acrylic acid w;th from 5 to 45X by ~e1ght
of a compound of the formula IV~ V or VI and/or sodium
vinylsuLfonate are prepared.
: :
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36554
The monomers, or a mixture of the monomers, are
dissolved in water or in a mixture of water with as much
as 25% by weight of isopropanol. The concentration of
the monomers in the solvent is from 30 to 70X by weight.
The polymerization is carried out in a powder
bed, ie. the powder is initially introduced into a poly-
merization apparatus. Suitable powd~rs are both inor-
ganic and organic pulverulent materiaLs which do not
react with the monomers or polymers under the reaction
conditions. Examples of suitable pulverulent inorganic
materials are quartz flour, talc, alumina, sodium chlor-
ide and glass beads. However, it 1s preferable to intro
du~e init;ally into the polymer;zation zone an inert
pulverulent polymer whose composition corresponds to that
of the polymer being formed from the monomer mixture or
from the monomers to be polymerized. Where a pulverulent
polymer is not available, these polymers are prepared by
a conventional polymerization method, for example by
polymerizing the monomers in the absence of a solvent
and comminuting the solid polymer, by polymeri-ing ~he
monomers in a water-in-oil emulsion and precip;tating
and isolating the resulting polymer, or by precipitation
polymerization or bead polymeri2ation. The particle dia-
meter of the pulverulent materials is from 10 ~m to 20
mm.
Examples of suitable polymerization apparatuses
are kettles, st;rred autoclaves, if appropriate in the
form of multi-stage cascades~ and combinat;ons of stirred
~ettles with a downstream flow tube~
The powder state in the polymerizat;on zone is
maintained during the entire duration of polymerization.
The monomer solution or emuls;on is preferably applied in
finely divided form onto the powder in the polymerization
zone. This process step is carried out~ as a ru~e~ by
sprayiny the monomer solution either onto the powder bed
or d;rectly in the powder bed. The monomers are
2~
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3655~
;ntroduced into the polymerization zone at the rate at
~hich they are polymerized. This can be effected either
continuously or batchw;se. Dur;ng the polymerization,
care should be taken to ensure that the reaction materia~
is adequately circulated. The mixture is preferabLy
stirred. The heat formed during polymerization~ and that
result;ng from circulation of the powder, are removed by
continuously evaporating the solvent or the solvent mix-
ture from the reaction zone. Preferably, the concentra-
tion of the monomers in the organic solvent is chosen sothat, when polymerization of the monomers is complete,
the enthalpy of polymerization liberated is just suf-
ficient, under the preva;ling reaction conditions, to
remove the solvents completely from the polymerization
zone by evaporation~ The concentration of the monomers
in the solvent is therefore preferably from 45 to 60X by
weight.
The polymerizat;on is carried out in the presenc`e
of a conventional polymerization initiator, preferabLy
one wh;ch is soluble or emulsifiable in water~ eg. hydro-
gen perox;de, sod1um peroxydisulfate, potassium peroxydi-
sulfate or a~monium peroxydisulfate. Other su;table
initiators are the conventional redox catalyst systems,
such as metal salts and peroxides, water-soluble azo
compounds, such as 2,2'-azobis~2-amidinopropane) hydro-
ch~or;de, and ketone perox;des, such as acetylacetone
peroxide. For example, from 1 to 20% by ~eight, based on
the monomers, of hydrogen peroxide or of one of the other
water-soluble initiators is used.
An essential feature of the no~e~ process is that
from 40 to 95, preferably from 70 to ~Q, X of the acid;c
groups of the monomers a), b) and c) are neutralized, and
` that the polymerization is carrled out in the presence of
from 0.5 to 10~ preferably from S to 8, moleX, based on
the monomers~ of specially selected regulators. The
monomers can be ;ntroduced ;nto the polymerization zone
, . .
. ~
9~
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in partially neutralized form, or can be partially
neutral;zed only after being introduced, and the base can
be employed in solid form or in solution. If ammonia or
a lo~-boiling amine is used as the base, this can also be
introduced into the polymerization zone in gaseous form.
Preferably, the neutralization of the monomers containing
acidic groups ;s carried out in the polymerization zone~
In this case, the solvent for the monomers has to conduct
a~ay not only the heat of polymerization but also the
heat of neutral;zat;on. Examples of su;table bases are
sodium hydroxlde solution, potassium hydroxide solution,
ammonia, amines, sodium carbonate, potassium carbonate,
calcium carbonate, calcium hydroxide, calcium oxide and
the oxides, hydroxides, carbonates and bicarbonates of
magnesium and barium.
The regulators are thiocarboxylic acids, eg.
thioglycolic acid, th;olac~ic acid, 3-mercaptopropionic
acid, 2-mercaptobutyric acid and 3-mercaptosuccinic acid,
and enol-ethers of the general formula
CH_~R ~III)
where R is C1-C5-alkyl. The thiocarboxylic acids can be
represen~ed, for example, by the formula
HS-R-COOH tVII)
~here R is C1-~-alky~ene. Preferably used regulators are
thioglycolic acid and 2-mercaptoethanol. Another group
of regulators are salts or chelates of copper and of
transit;on metals of sub-group 8 of the per;odic table.
Preferably used compounds are those which are soluble in
the solvent for the monomers, eg~ Cu(N03)2, CuS04, copper
acetate, FeS04, fe~N03~z, MnS04, Mn~II) acetate,
to(N03)2 or NitN~3)2
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3~554
Depending on the reactivity of the monomers and
the e~f;ciency of the initiator, the polymer;zation of
the monomers can be carried out ~ithin a ~;de temperature
range. ~t is only important that the po~der state is
maintained during the polymerizat;on, ;e. the ~emperature
should be 10~ or more below the melting po;nt or the
beginning of the softening range of the polymers, so that
they do not stick together. Another obvious pre`condition
;s that the temperature must be suff;ciently hi~h for the
particular solvent used to evaporate from the polymer;za-
t;on zone. The polymerizat;on can be carried out under
atmospheric, reduced or superatmospher;c pressure, for
example at as high as 25 bar. It is preferably carried
- out under atmospheric pressure at from t15 to 280C, pre-
ferably from 120 to 150C. It can take place batch~ise
or continuously, and the vesse~ for the reaction 20ne in
each case can be a stirred kettle or a dynamic mixer of
any type. For continuous operation, the monomer solution
is mixed with the initiator and the regulator, after
Z0 which the mixture is fed continuously or at intervals to
the reaction zone, and the polymer is removed therefrom
continuously or batchwise v;a a suitable d;scharg;ng
apparatus, egO a scre~. The polymer ;s removed at about
the same rate as the monomers are ;ntroduced ;nto the
reaction zone. The în;t;ator can be introduced ;nto the
polymerization zone either together ~ith the solution of
the monomers or separately from this. The same appl;es
to the regulator used.
The process accord;ng to the invent;on gives
3~ homopolymers or copolymers of acryl;c ac;d or methacryL;c
acid having K values of from 8 to 20, prefera~Ly below
15, for example from 10 to 14. The polymers prepared by
the novel process have a different molecular weight dis-
tribution to those obtained, for example, by polymeriza-
tion in solut;on~ The novel process gives pulverulentpolymers whose part;cle diameters are from 10 ~m to 2 cm,~
.
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preferably from 0.1 to 5 mm~
The copolymers thus prepared are used as m;Lling
ass;stants and dispersants, or as d;spersants for the
production of highly concentrated aqueous p;gment suspen-
sions for coating compos;tions for paper. The copolymersare used in amounts of from 0.5 to 1.0~ preferably from
0~3 to 0.6, X by weight, based on pigment. Examples of
suitable pigments for the production of coating composi-
t;ons for paper are chalk, clay from primary and second-
ary depos;ts, sat;n wh;te, t;tan;um d;ox;de, ~aolln anddolomite. For paper coat;ng, these p;gments are converted
to h19hly concentrated aqueous suspens;ons, same of wh;ch
can have a solids content as h;gh as 90% by we;ght,
depending on the type of pigment and its particle size.
The solids contents of clay suspensions are f~om 65 to 70%
by we;ght, wh;le those of aqueous chalk suspens;ons are
from 75 to 85% by weight, and in some cases e~en as high as
90X, part;cularly where the pigments used have a broad par-
ticle size spectrum. The aqueous suspensions are prefer-
ab~y prepared by adding the dispersant to the pigments atas early a stage as the mill;ng. As is known, this mil-
ling process is carried out in an aqueous medium. In the
case of chaLk, for example, 90~ ;s m; lled to a particle
size of < 2 ~m, while in the case of clay 85~ of the pig-
ment particles have a size of less than 2 ~m. The totalamount of dispersant can be added at as early a stage as
the mi lling process, or the dispersant can be dissolved
;n water and the pulverulent p;gments ;ntroduced ;nto
this solution. If the copalymers are used as m;ll;ng
assistants, they are employed in the same amount as
stated above for the d;spersants. For milling and/or
dispersing chalk, pre~erably from 0~3 to 0.6X by ~e;ght
of the homopolymers or copolymers is required~ whereas
for clay amounts of from 0.1 to 0.4X by weight are suit-
able for the stated applications. In the preparation ofaqueous chalk suspensions, even small amounts of the
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homopolymers or copolymers have a clearly better dis-
pers1biL;ty than the best commercial poLyacryLate-based
products used hitherto for this purpose. For the pre-
parat;on of highly concentrated aqueous chalk suspensions
having a particular viscosity, the requ;red amount of a
polymer prepared according to the invention is about 20X
less ~han that of a conventional prior art acrylate when
these polymers are used as dispersants. The homopolymers
of acryl;c acid and the copolymers containing sulfonic
1û ac;d groups are therefore preferably used for the pre-
paratlon of highly concentrated aqueous chalk suspensions
for coating compositions for paper. The pH of the pig-
ment suspens;ons is from 7 to 12.5, preferably from 7.5
to 10. For the purposes of the present invention,highLy
concentrated aqueous suspensions are those in which the
pigment content is not less than 65% by weight.
Another important fie~d of use for the homopoly-
mers and copoLymers obtained by the noveL process ;s the
detergent sector. The polymers are used as encrustation
inhibitors and antiredeposition agents in detergents,
the amounts used for this purpose being from 0.5 to 5X,
based on the ready-prepared detergent.
In the Examples ~hich foLlow, parts and percent-
ages are by weight, unless stated otherwise. The K
values were measured in accordance with H. Fikentscher,
CeLlulose Chemie ~3 ~1932), 48-64 and 71-74, in 5%
strength aqueous sodium chloride solution at a polymer
concentration of O.SX by weight and at 25C; K = k . 103.
The viscosity of the aqueous pigment suspensions
was determined using a BrookfieLd viscometer, at 20C and
100 rpm.
The polymerization reactor used was a cylindrical
glass vessel which had a capacity of ~.5 Liters and was
equipped with a helical stirrer and a descending con-
denser~ A spray nozzle, through which the monomer mix-
ture, the in;t;ator and the reguLator were sprayed onto
.
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the initially taken nylon granules~ entered the glass
vessel. Furthermore, a nitrogen i;ne entered the reactor,
so that the polymer;zation could be carried out under a
nitrogen atmosphere. The polymerization vessel was
heated by means of an o;lbath. The monomer mixture was
mixed with the solution of the polymer;zation initiator
using a static mixer. A heat exchanger was incorporated
;n the line through which the monomer mixture was fed to
the static m;xer, so that, if requ;red, the mixture could
be cooled. A separator ~as incorporated between the
polymer;zat;on vessel and the descending condenser in
order to separate off any sol;ds entrained by the nitrogen
stream, the vapor;zlng excess monomer or the boiling
assistant. To monitor the temperature of the react;on
mix~ure, the polymerization reactor was pro~ided with a
temperature sensor extending ;nto the reaction m;xture.
In order to be able to carry out polymeri~ation and neu-
tralization simultaneously in the reactor, either the
latter was connectet to a solids-metering apparatus, for
Z0 example a metering screw, by means of which pulverulent
neutral;zing agent was metered into the reactor~ or the
glass vessel was entered by a second spray noz~le
through which the liquid neutraliz;ng agent was likewise
sprayed onto the initially taken granules.
In the a~paratus described above, 1,500 9 of a
granulated nylon, obtained from adlpic acid and hexa-
methylenediamine and having a particle diameter of Z.5 -
3.5 mm, were initially taken, and were heated to 140C
with thorough circulat;on.
EXAMPLE 1
A solution of 151.5 9 of 2-acrylamida-Z-methyl-
propanesulfon;c acid tAMPS), 165 9 of ~ater,~859.2 9 of
acrylic acid ~AA~ and 0.1 9 of iron~ sulfate hepta-
hydrate, an initiator solution comprising 17~.Z g of SOZ
strength hydrogen peroxide and 96 9 of water, and a regu-
lator solution comprising 87.3 9 of th;oglycolic acid~
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54.8 9 of water and 116.8 9 of isopropanol were combined,
in a stat;c mixer, in a volume ratio of about 3.6:1:1,
and the m;xture was sprayed success;vely, ;n the course
of 3 hours, onto the ag;tated bed of pulverulent nylon.
At the same time, 430.2 9 of 100X strength sodium hydrox-
;de ~ere introduced uniformly, likewise in the course of 3
hours ~degree of neutral;zation: 85 mole%). The molar
ratio of AMPS to AA was about 1:16~ and the polymeriza-
tion temperature was 140C. During the polymerization,
the powder state in the polymer;zation zone was ma;n-
ta;ned, and the water and ;sopropanol fed in, as well as
the water liberated during the neutralization, were d;s-
t;lled off cont;nuously ~about 600 9 of condensate). To
decrease the residual monomer content, 229.5 9 of hydro-
gen peroxide and 394 9 of water were then sprayed, in thecourse of 4 hours, onto the still agitated sol;ds bed,
the temperature of the reaction mixture be;ng 140C and
the amount of water fed in once again being distilled off
continuously. The reactor content was then milled in a
Z0 ball mill for about 10 hours, w;th the result that the
copoLymer formed separated as a powder from the initially
taken nylon granules and could be isolated by sieving.
The resulting copolymer had a K value of 10.6
and a res;dual monomer content of less than 1%.
EXAMPLE 2
In the polymerizat;on apparatus described above,
the sol1ds-metering apparatus was replaced by a second
spray apparatus for aqueous sodium hydroxide solution. In
the reaction vessel, 1,500 9 of a ~ranulated nylon having
a particle diameter of 2.5 - 3.5 mm were initially taken,
and ~ere heated to 135C ~ith thorough circulat;on.
A solution of 151.5 9 of AMPS, 150 9 of water,
~ 859.2 9 of AA and 0.1`9 of iron~II) sulfate heptahydrate,
- an init;ator solut;on compr;s;ng 172.2 9 of 50X strength
35 hydrogen peroxide and 115.7 9 of water, and a;regulator
solution comprising 87.3 9 of th;oglycolic ac;d and
.
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205.7 9 of water ~ere combined, in a static mixer~ in a
voLume ratio of about 3.4:1:1, and the mixture was
sprayed successively, in the course of 3 hours~ onto the
agitated bed of pulverulent nylon. At the same time, a
soLut;on of 430.8 9 of sodium hydroxide in 184.5 9 of
water, at 80C, was sprayed un;formLy, like~ise in the
course of 3 hours, onto the thoroughly agitated surface of
the stirred solids bed tdegree of neutraLiza~ion: 85 moleX).
The molar ratio of AMPS to AA was about 1:16, and the poly-
1û merization temperature was 135C. During the polymeriza-
tlon, the powder state in the polymerizatlon zone was
ma1nta1ned, and the water fed in, as weLl as that liberated
during the neutralizatlon, was d1st1lled off continuously
tabout 950 9 o~ condensate~. To decrease the residual
monomer content, Z29.7 9 of hydrogen perox;de and 867.7 9
of water were sprayed, in the course of 4 hours, onto the
thoroughLy agitated solids bed, the temperature of the
react;on mixture being 135C and the amount of water fed
in being distiLLed off continuously. The reactor content
was worked up as descr;bed in ExampLe 1. ~he resulting
copolymer had a K vaLue of 12.0, a degree of neutralization
of 85Z and a residuaL monomer content of Less than 0.5X.
EXAMPLE 3
The poLymeri2ation apparatus used ~as that des-
cribed in E~ampLe 1. In the reaction vesseL, 1,500 g of
a granuLated nyLon having a particLe diameter of 2.5 -
3O5 mm ~ere initiaLLy taken, and ~ere heated to 140C
~ith thorough circuLation and ~Lush1ng ~ith nitrogen.
A solution of 151.2 9 of AMPS, 165 9 of ~ater,
859.2 9 of AA and 0.1 9 of iron(II) suLfat& heetahydrate,
an in;tiator solution compris;ng 172.2 9 of 50X strength
hydrogen peroxlde and 115.7 9 of water, ~and a regulator
solution comprising 117.5 9 of thiogLycolic acid and
205.7 9 of water were combined, in a static mixer, in a
Yolume ratio of about 3.4~ and the mixture was
sprayed successively, in the course of 3 hoursr onto the
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agitated solids bed. At the same time, 430.2 9 of 100%
strength sodium hydroxide were introduced uniformly into
the reactor, likewise in the course of 3 hours (degree of
neutralization: 85 moleX~O The molar ratio of AMPS to
AA ~as about 1:16, and the polymerization temperature ~as
140C. During the polymerization, the powder state in
the poLymerization zone was maintained, and the water fed
in, as well as that liberated during the neutralization,
was distilled off continuously ~about 1,000 9 of conden-
sate). To decrease the residual monomer content~ 229.5 9of hydrogen peroxide and 867.7 9 cf ~ater were sprayed,
in the course af 4 hours, onto the thoroughly agitated
solids bed, the temperature of the reaction mixture being
140C and the amount of water fed in being distilled off
cont;nuously. The reactor content was worked up as des-
cribed in Example 1. The resulting copolymer had a K
value of 8.2 and a residual monomer content of ~ess than
1 % .
EXAMPLE 4
In the polymerization apparatus described in
Example 2~ 1,500 9 of a granulated nylon having a par-
ticle diameter of 2.5 - 3.5 mm ~ere initially taken, and
~ere heated ~o 140~ with thorough circulation. A solu-
tion of 30~ 9 of AMPS, 300 9 of water, 859.2 g of AA and
0.1 9 of iron(II) sulfate heptahydrate, an init;ator soLu-
tion comprising 173.3 9 of 50% strength hydrogen peroxide
and 115.7 9 of water, and a regulator solution comprising
117.5 9 of thioglycolic acid and 5S.7 9 of water ~ere com-
bined, in a s~atic mixer, in a ~olume ratio of about
-30 6.5:1.7:1, and the mixture was sprayed successively, in the
course of 3 hours, onto the agitated solids bed. At the
same time, a solution of 430.8 9 of sodium hydroxide in
184.5 9 of water, at 80C, was sprayed uniformly,likewise
in the course of 3 hours, onto the thoroughly agitated sur-
face of the stirred solids bed ~degree of neutralization:80 mole%). The molar ratio of AMPS to AA was about 1:8, and
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36554
the polymerization temperature was 140C. During the poly-
merization, the powder state in the polymerization zone
was maintained, and the water fed in, as ~ell as that
~iberated during neutralization, was distilled off con-
5 tinuously (about 900 9 of condensate). To decrease theres;dual monomer content, 2Z9.7 9 of hydrogen peroxide
and 86707 9 of s ater ~ere sprayed, in the course of 4
hours, onto the thoroughly agitated solids bed, the
temperature of the react;on m;xture being 140C and the
10 amount of water fed in being distilled off continuously.
The reactor content was worked up as described in Example
1~ The resulting copolymer was 8ûZ neutralized and had a
K value of 11.2 and a residual monomer content of l~ess
than 0.5X.
EXAMP~E 5
A solution of 872.7 9 of AA and 0.1 g of iron(II)
sulfate heptahydrate, 183.6 9 of a 25Z strength aqueous
so~ution of sodium vinylsulfonate in 190.9 ~ of water, an
initiator solution comprising 169.7 9 of 50X strength
20 hydro~en peroxide and 38.1 9 of ~ater, and a regulator
solution comprising 85.5 g of thioglycolic acid and
155.3 g of water ~ere combined, in a static mixer, in a
volume ratio of about 4.2:1.8:1:1.2, and the mixture was
sprayed successively, in the course of 3 hours, onto the
25 agitated bed of pulverulent nylon. At the same time, a
solution of 387.8 9 of sodium hydroxide in 166.3 g of
water, at 8ûC, was sprayed uniformly, likewise in the
course of 3 hours, onto the thoroughly agitated surface of
the stirred solids bed~ The weight ratio of sodium vinyl-
30 sulfonate to acryl;c acid was about 1:19~ and the polymeri-
zation temperature s~as 140C. During the polymerization,
the pouder state in the polymerization zone wàs maintained,
and the water fed in, as well as that liberated during
neutralization, was distilled off continuously (about 890 9
35 of condensate). To decrease the residual monomer content,
Z07.4 g of 50X strength hydrogen peroxide and 413.7 g of
- 16 - O.Z. 0050/36278
- 36554
water were sprayed, in the course of 4 hours, ~nto the still
ag;tated solids bed, the temperature of the react;on mix-
ture being 140C and the amount of water fed in being
distilled off cont;nuously~ The reactor content was
~illéd in a ball mill for about 10 hours, with the result
that the copolymer formed separated as a po~der from ~he
in;t;ally taken nylon granules and could be ;solated by
sieving.
The result;ng copolymer had a K value of 12.8, a
res;dual monomer content of less than 1% and a degree of
neutralization of 80X.
EXAMPLE 6
The polymerization apparatus used corresponded to
that descrlbed in Example 2. In the reaction vessel,
1,500 9 of a granulated nylon having a particle diameter
of Z.5 - 3.5 mm were initially taken, and were heated to
140C w;th thorough circulat;on. A solut;on of 918.1 9
of AA, 100 9 of water and 0.1 9 of iron~II) sulfate
heptahydrate, an ;nitiator so-ution comprising 173.4 9 of
50X strength hydrogen peroxide and 109.8 9 of water, and
a regulator solution comprising 88 9 of th;oglycol;c
ac;d and ~0.6 9 of water were comb;ned, in a static mi%er,
in a volume ratio of about 6:1.8:1, and the mixture was
sprayed successively, in the course of 3 hours, onto the
ag;tated sol;ds bed. A~ the same t;me, a solut;on of
433.5 9 of sodium hydroxide in 185.7 9 of water, at 80~,
was sprayed uni~ormly, likewise in the course of 3 hours,
onto the thoroughly ag;tated surface of the st;rred sol;ds
bed~ The polymer;zation temperature was 140C. During
the polymer;zation, the powder state in the polymerization
zone was maintained~ and the water fed in, as we~l as that
liberated during neutral;7at;on, ~as dist;ll~d off con-
t;nuous~y. To decrease the residual monomer content, ~31~Z g
of 50X strength hydrogen peroxide and 435.Z g of water
were sprayed, in the course of 4 hours, onto the thoroughly
agitated solids bed, the temperature of the reaction
- 17 - O.Z. ûO50/3~278
36554
mixture be;ng 140C and the amount of water fed in being
d;stilled off ccntinuously. ~he reactor content was
~orked up as described in Example 1. The resulting
polymer was 85% neutralized and had a particle diameter of
0.1 mm, a K value of 13.0 and a res;dual monomer content
of less than 1%.
EXAMPLE 7
A solution of 872.7 9 of AA and û.1 9 of iron~II)
sulfate heptahydrate, 183.6 9 of a 25X strength aqueous
soLution of sodlum vinylsulfonate in 190.9 9 o~ water, an
initiator solution comprising 169.7 9 of 50~ strength
hydrogen perox;de and 38.1 9 Gf water, and a regulator
soluticn compris;ng 71 9 of 2-mercaptoethanol and 155.3 g
of ~ater were combined, ;n a static mixer, in a volume
ratio of about 4~2:1.8:1:1.1, and the mi~ture was sprayed
successively, in the course of 3 hours, onto the agitated
bed of pulverulent nylon. At the same time, a solution
of 387.8 9 of sodium hydroxide in 166.3 9 of water, at
80C, was sprayed uniformly, again in the course of 3
2~ hours, onto the thoroughly agitated surface o~ the stirred
so~ids bed. The weight ratio of sodium vinylsulfonate to
acrylic acid was about 1:19, and the polymerization
temperature was 140C. During the polymerization, the
powder state in the polymerization zone was maintained, and
~5 the water fed in~ as well as that liberated during
neutral;zation, was distilled of~ cont;nuously (about 890
g of condensate~. To decrease the residual mqnomer
content, 207.4 g of 50X strength hydrogen pero~ide and
413.7 9 of water were sprayed, in`the course of 4 hours,
- 30 onto the still agitated solids bed, the temperature of the
reaction mixture being 140C and the amount of ~ater fed
in being distilled off continuously.
The reactor content was then milled in a ball mill
for about 10 hours~ ~ith the result that the copolymer
formed separated as a powder from the initially taken nylon
granules and could~be isolated by sieving~
97
- 18 - ~ O.Z. 0050/36Z78
36554
The resulting copolymer had a K value of 12.2, a
residual monomer content of less than 1X and a degree of
neutralization of 80%.
EXAMPLE 8
A solution of 780c9 g of AA and 0.1 9 of iron(TI~
sulfate heptahydrate, 550.8 9 of a ~5X strength aqueous
solution of sodium vinylsulfonate, an initiator solution
comprising 16Z.1 g of 50S~ strength hydrogen peroxide and
44.3 9 of water, and a regulator solution comprising 63.5
tO g of 2-mercaptoethanol and 20 9 of ~ater were combined,
in a static mixer, ln a volume ratlo of about ~.3:6.6:2.5
:1, and the mixture was sprayed successively, in the
course of 3 hours, onto the moving bed of pulverulent
nylon. At the same time, a solution of 347.1 9 of sod
ium hydroxide in 148.7 9 of water, at 80C, was sprayed
un;formly, likewise in the course of 3 hours, onto the
thoroughly agitated surface of the stirred solids bed. The
weight ratio of sodium vinylsulfonate to acrylic acid was
about 1:5.7, and the polymerizatisn temperature ~as
140C. During the polymerization, the powder state in
the polymer;zation zone was maintained, and the water fed
in, as well as that liberated during neutralization, was
disti lled off continuously (about 870 9 of condensate~.
To decrease the residual monomer content, 216 9 of 50%
strength hydrogen peroxide and 417.6 9 of water were
sprayed, ln the course of 4 hours, onto the st;ll ag;~ated
solids bed, the temperature of the reaction mixture being
14ûC and the amount of water fed in being distilled off
continuowsly.
The reactor content was--then milled in 3 ball mi ll
for about 1~ hours, with the result that the copolymer
formed separated as a powder from the initially taken nyLon
granules and could be isolated by sieving.
The resulting copolymer had a K value of 12.3, 3
residual monomer content of less than lX and a degree of
neutral; 2 ation of 80%.
~2~ 7
- 19 - O.Z. 0050/36278
36554
EXAMPLE 9
A so~ut;on of 780.9 9 of AA and 0.1 9 of ;rontII)
sulfate heptahydrate, S50.8 9 of a 25X strength aqueous
soLution of sodium vinylsulfonate, an initiator solution
S compr;q;ng 1~2.1 9 of 50~ strength hydrogen perox;de and
44.3 9 of water, and a regulator solution comprising 63.5
g of Z-mercaptoethanol and 20 9 of water were combined,
;n a stat;c m;xer, ;n a volume ratlo of about 9.3:6.6:2.5
:1, and the m;xture was sprayed successively, ;n the
course of 3 hours, onto the moving bed of pulverulent
nylon. At the same time, a solution o~ 303.6 9 of sod-
ium hydroxide in 130.1 9 of water, at 80C, was sprayed
uniformly~ l;kewise ;n the course of 3 hours, onto the
thoroughly ag;tated sur~ace of the stirred so l7 ds bed. Tha
we;ght rat;o of sodium v;nylsulfonate to acrylic ac;d was
about 1:5.7, and the polymer;zat;on temperature was 140C.
Dur;ng the polymerization, the po~der state in the poly-
merization zone ~as maintainedr and the water fed ;n, as
well as that liberated during neutralization, was ~istilled
off continuously tabout 800 9 of condensate). To decrease
the residual monomer content, 216 ~ of S0~ strength
hydrogen peroxide and 418 9 of water ~ere sprayed, in the
course of 4 hours, onto the still ag;tated solids bed, the
temperature of the reaction mixture being 140C and the
amount of water fed in being distilled off cont;nuously~
The reactor content was then milled ;n a ball mill
for about 10 hours, with the result that the copolymer
formed separated as a powder from the in;t;ally taken nylon
granules and could be ;solated by sieving.
The resul~ing copolymer had a K value of 10~5, a
residual monomer content of less than 1X and a degree of
neutral;zat;on of 70%.
EXAMPLE 10
A solution of 716.7 9 of AA and 0.1 9 of irontII)
sulfate heptahydrate, 808.8 9 of a 25X strength aqueous
solut;on of sod;um v;nylsulfonate, an in;t;ator solution
~%~
- 20 - O.Z. 0050/36278
36554
comprising 156.6 g of 50X strength hydrogen peroxide 3nd
30.9 9 of water, and a regulator solut;on compr;s;ng 67.5
g of 2-mercaptoethanol and 20 9 of water were com~ined~
in a static mixer, in a volume ratio of about 8.2:9.2:2.1
:1, and the mixture was sprayed success;vely, in the
course of 3 hours, onto the moving bed of pulverulent
nylon. At the same time, a solut;on of 318.5 9 of sod-
;um hydrox;de ;n 136.5 g of water, at 80C, was sprayed
uniformly, l;kewise in the course of 3 hours, onto the
thoroughly ag;tated surface of the st;rred sol;ds bed. The
~e;ght rat;o of sodium v;nylsulfonate to acrylic ac;d was
about 1:3.5, and the polymerizat;on temperature was 140C.
Dur;ng the polymer;zation, the powder state ;n the poly-
mer;zae;on zone was ma;nta;ned, and the water fed ;n, as
well as that l;berated during neutralization, was distilled
off continuously tabout 1,000- 9 of condensate). To decrease
the res;dual monomer content, 208.8 9 of 50% strength
hydrogen peroxide and 420 9 of water were sprayed, in the
course of 4 hours, onto the still agitated solids bed, the
Z0 temperature of the reaction m;xture being 140C and the
amount of water fed ;n being distilled off continuously.
The reactor content was then milled in a ball mill
for about 10 hours~ with the result that the copolymer
formed separated as a powder from the initially taken nylon
Z5 granules and ~ould be isolated by sieving.
The result;ng copolymer had a K value of 10.7, a
residual monomer content of less than 1% and a degree of
neutral;zat;on of 80X.
EXAMPLE 11
A solut;on of 897.9 9 of AA, 328.6 9 of water and
0~1 9 of ;ron~II) sulfate heptahydrate, an ;n;t;a~or
solut;on compris;ng 169.7 9 of SOX strength hydrogen per-
oxide and 38.1 9 of water, and a regulator so~ut;on com-
pr;sing 71 9 of 2-mercaptoethanol and 155.3 9 of water
were combined, in a stat;c m;xer, in a volume ratio of
about 3.9:0.9Z:1, and the m;xture was sprayed
- Z1 - O.Z. 0050/36278
36554
success;vely, in the course of 3 hours, onto the moving
bed of pulverulent nylon. At the same time, a solu~ion
of 387.8 g of sodium hydroxide in 166.3 9 of ~ater, at
80C, was sprayed uniformly, aga;n in the course of 3
S hours, onto ~he thoroughly agitated surface of the stirred
solids bed. The polymerization tem~erature was 140C.
D'ur;ng the polymer;zation, ~he powder state ;n the poly-
merization zone was mainta;ned, and the water fed in~ as
well as that l;berated during neutralization, ~as dis-
til~ed off continuousLy ~about 880 9 of condensate). Todecrease the residual monomer content, 207.4 9 of SOX
strength hydrogen peroxide and 413.7 9 of water were sprayed,
in the course of 4 hours~ onto the still agitated solids
bed, the temperature of the reaction mixture being 140C and
the amount of uater fed in being dist;lled of T continuous~y.
The reactor content was then milled in a ball mil~
for about 10 hours, ~ith the result that the copolymer
formed separated as a powder from the initially taken nylon
granules and could be separated by sieving.
The resulting copolymer had a K value of 13.1, a
residual monomer content of less than 1% and a degree of
neutralization of 78%.
Preparation of aqueous pigment suspensions: general
method
In a 2 liter stirred stainless steel vessel, 4 9
of one of the dispersants shown in Table 1 ~a 1û0%
strength polymer in each case) were dissolved ~n 1 liter of
water in each case. Using a high-speed laboratory st;rrer,
780 9 of a finely divided milled ca~cium carbonate ~in
wh;ch 90X of the particles had a size of < 2 lum) were ;n-
troduced a litt~e at a time ;n the course of Z0 minutes,
~ith ~;gorous stirring, care being taken to ensure that the
pigment added ~as substant;ally dispersed. The pH of the
pigment suspension was brought to 9 by adding aqueous sodium
hydroxide solut;on. The m;xture ~as then homogenized for a
further S minutes at room ~emperature, after which the
~z~
- 22 - O.Z. 0050~36278
36554
viscosity of the aqueous pigment suspension was measured.
EXAMPLE 12
Using the general method for the preparation of
aqueous suspensions of chalk pigments for paper-coating
compositions, 78~ strength suspensions were prepared,
using 0~4Xo by weight, based on pigment, of the copolymer
~copolymer 1) obtained as described in Example 1. Thq~
viscosity of the aqueous pigment suspensions was measured
at ~ar;ous temperatures. For compar;son, a 78% strength
aqueous suspens;on of the same p;gment was prepared using
the comparat;ve d;spersant based on a polyacrylate. The
vlscoslty of the convent;onal p;gment suspens;ons was
l;kew;se measured at var;ous temperatures. The results
are summar;sed in Table 1, from which ;t can be seen that
the v;scos;ty of aqueous p;gment suspens;ons prepared
us;ng a convent;onal d;spersant decreases more sharply
with ;ncreas;ng temperature than that of the aqueous p;g~
ment suspensions prepared using a copolymer according to
the invention.
Z~ TA8LE 1
Dispersant Viscosity ~mPa.s] of the aque-
ous suspension at
25~4ûCS5C70C
Copolymer 1 870 670 620 600
Comparative dispersant 920 640 480 390
EXAMPLE 13
3 different 78X strength chalk suspensions were
prepared, all of the suspensions having a pH of ~ and the
suspensions differ;ng only in the amount of dispersant
used in each case. The d;spersants used were the copoly-
mers prepared as descr;bed in Examples 2 and 3 (copoly-
mers 2 and 3 respectively). The amounts of 100% strength
copolymer used, and the viscosities o~ 78~ ~trength aque-
ous chalk suspensions, are shown in Table 2. For
~2~
23 ~ 0 ~ Z n 0 050 /3 6Z78
36554
comparison with the prior art, three different suspen-
sions containing different amounts of the comparative
d;spersants were also prepared.
TA8LE Z
Dispersant Viscosities rmPa.s~ of the 78%
strength aqueous chalk suspen-
sion with the addition of
0.35X by 0.4X by 0.5% by
weight weight weight
of dispersant
1 0
Copolymer 2 2,350 870 510
Comparative dispersant 3,100 920 650
Copolymer 3 2,400 900 550
Table 2 shows that even a very smalL amount of
copolymer 2 or 3 is sufficient to achieve effect;ve dis-
persing of the pigment in comparison with the prior art.
EXAMPLE 14
Various 78% strength aqueous chalk suspensions
were prepared~ the dispersants used being acrylic acid
-copolymers containing various amounts of acrylamido-
propanesulfonic acid. The results are shown in Table 3~
and are compared with the results obtained using the com-
parative dispersantO
TABLE 3
Copolymer Viscosity of the aqueous
obtained suspension with the addi-
from acrylic acid tion of
and~AMPS*)
Copolymer AA~) AMPS 0.35~ o~ 0.50% of
No. % by X by dispersant dispersant
weight weight (solid) (solid)
. . . ~
2 85 15 570 460
4 70 30 5~0 440
Comparative
dispersant 100 1,900 380
.
*)AMPS = 2-acrylamido-2-propanesulfonic acid
AA = acrylic acid
~2~9~
- 24 - O~Zo 0050/36278
36554
EXAMPLE 15
To demonstrate the efficiency of the polymers
prepared by the polymerization process carried out in the
stirred soLids bed, and for comparison ~ith convention-
ally prepared prior art encrustation inh;b;tors based onpolyacryl;c acid~ series of 20 ~ashes each were carried
out in a Launder-0-meter, and the changes ;n the ash con-
tent were taken as a measure of the efficiency of encrus-
~tat;on inhib;tion.
10 Test cond;tions:
liquor: Z5û ml
liquor rat;o: 1:12.5
hardness of the water: 22d (8.5 ca:1.5 Mg)
duration: 45 minutes
temperature: 40-95C (temperature program)
test fabric: 10 9 of cotton 22Z and 10 9 of terry cloth
in each case
detergent: 8 g/Liter torthophosphate-containing)
amount of inh;b;tor added: 2X by weight
TA8LE 4
No. Encrustation inhibitor Ash content in X
Cotton 222 Terry cloth
1 None 2.54 6.38
2 Comparative encrustation
inhibitors1) 1.92 3.56
3 PAS-Na 1.S6 3.34
4 PAS/AMPS-Na 1.32 2.71
PAS-NH4 1.60 2.72
1) Conventionally prepared prior art encrustation
inhibitors based on polyacrylic acid
2) Na salt of polyacrylic acid
9~
25 ~ 0 ~ Z a 0050 /3 6278
36554
The ~est results summarized in Table 4 show that,
w;th regard to encrustation inhibition~ the products pre-
pared by the novel process and based on polyacrylic acid
are clearLy superior to those prepared by a conventional
standard method.
EXAMPLE 16
Using the general method for the preparation of
aqueous suspensions of chalk pigments for paper-coating
compositions, 78X strength suspensions were prepared,
us;n~ 0.4X by we;ght, based on pigment, of the copolymer
~copolymer 7) obta;ned as descr;bed in Example 7. The
viscosity of the aqueous pigment suspensions was measured
at various temperatures. For comparison, a 78% strength
aqueous suspension of the same pigment ~as prepared using
the comparative dispersant ~ased on a polyacrylate having
a K value of 16. The viscosity of the conventional pig-
ment suspensions was likewise measured at various tempera
tures. The results are summar;zed in Table 5, from which
it can be seen that the viscosity of aqueous pigment sus~
pensions prepared using a conventional dispersant
decreases more sharply with increasing temperature than
that o~ the aqueous pigment suspensions using a copo~ymer
accord;ng to the invention.
TABLE 5
Dispersant Viscosity tmPa.s~ of the aqueous
suspension at
25C 40C 55C 70C
Copolymer 7 8Z0 720 680 640
Comparative dispersant ~20 640 480 390
EXAM~LE 17
3 d;fferent 78X strength chalk suspensions were
prepared, all of the suspensions having a pH of 9 and the
35 suspensions differing only in the amount of dispersant
used in each case. The d;spersants used ~ere the
- 26 - ~.Z. 0050/36278
36554
copolymers prepared as described in Examples 7 and 9
(copolymers 7 and 9 respectively). The amoun~s of 100X
strength copolymer used,~and the viscosities of the 78%
strength aqueous chalk suspensions, are shown in Table 6.
For comparison with the prior art, three different suspen-
sions containing different amounts of the comparative
dispersant were also prepared.
TA~LE 6
10 Dlspersant Viscosities ~mPa.s~ of the 78X
strength aqueous chalk suspen-
sion with the addition of
0.35% by 0.4Y. by O.SX by
weight weight weight
:
Copolymer 7 2,200 820 410
15 Comparative dispersant 3,100 920 650
Copolymer 9 2,000 700 3~0
Table 6 shows that even a very small amount of
copolymer 7 or 9 ;s sufficient to achieve eff2ctive dis-
persinQ of the pigment in comparison with the prior art.
EXAMPLE 18
Var;ous 78% strength aqueous chalk suspensionswere prepared~ the dispersants used being acrylic acid
copolymers containing various amounts of sodium vinyl-
sulfonate. The results are shown in Table 7, and arecompared with the results obtained using the comparative
dispersant. TA~LE 7
Copolymer V;scos;ty of the aqueous
obta;ned suspension with the addi-
from acrylic t;on of
30 ac;d and
VSNa*)
Copolymer AA*) VSNa 0.35% of 0.50% of
No. X by X by d;spersant d;spersant
we;ght we;ght (solid) tsolid)
7 93 5 470 3O0
78 Z2 420 340
Comparative
d;spersant 1ûO 1,900 380
*) VSNa = sod;um vinylsulfonate
AA = acrylic acid
~ 7
- 27 - O~Z. 0050/362?8
36554
~ EXAMPLE 19
To demonstrate the efficiency of the polymers
prepared by the poLymerization process carried out in the
stirred solids bed~ and for comparison with convention-
S alLy prepared prior art encrustation inhibitors based onpoLyacrylic acid, series of 20 washes each were carried
out in a Launder-0-meter, and the changes in the ash con-
tent were taken as a measure of the ef~iciency of encrus-
tation inhibition.
Test cond~tions:
liquor: 25û ml
Liquor rat;o: 1:12.5
hardness of the water: 2Zd (8.5 Ca:1.5 Mg)
duration: 45 minutes
temperature: 40-95C ttemperature program)
test fabric: 10 9 of cotton 222 and 10 9 of terry cLoth
in each case
detergent: 8 g/Liter (orthophosphate-contain;ng)
amount of inhibitor added: ZX by weight
TA8LE 8
No. Encrustation inhibitorAsh content in %
Cotton 222 Terry cloth
1 None 2.54 6.38
2 Comparative encrustation
inhibitors1) 1.92 3.56
3 CopoLymer according ~o
Example 7 1.34 2~70
1) Conventionally prepared prior art encrustat~on
inhibitors based on polyacrylic acid
The test resuLts summari~ed in TabLe 8 show that,
with regard to encrustation inhibition, the products pre-
pared by the noveL process and based on polyacrylic acid
are clearly superior to those prepared by a conventional
standard method.
