Note: Descriptions are shown in the official language in which they were submitted.
CA 02334196 2008-01-10
METHOD FOR MAKING PAPER AND CARDBOARD AND RETENTION AND
DEWATERING AGENTS
The present invention relates to the technical field
of paper production and the polymers used in this field.
The invention relates to a process for producing a
paper or paperboard with improved retention and other
properties.
During the production of paper, paperboard, or the
like, it is well known to introduce into the pulp retention
aids whose function is to retain a maximum of fines and fillers
in the sheet. The beneficial effects that result from the
utilization of a retention aid are essentially:
- increased production and reduction of production
costs: energy savings, more reliable operation of the machine,
higher yield in terms of fibers, fines, fillers and anionic
finishing products, lower acidity in the circuit linked to a
decrease in the use of aluminum sulfate, and hence a reduction
in corrosion problems;
- an improvement in quality: better formation and
better look-through, an improvement in the moisture content,
the opacity, the gloss, and the absorptive capacity of the
sheet, and a reduction in the porosity of the paper.
Long ago, it was proposed that bentonite be added to
the pulp, possibly together with other mineral products such as
aluminum sulfates or even synthetic polymers, notably
polyethylene imine (see for example the documents
DE-A-2 262 906 and US-A-2 308 635).
In the document US-A-3 052 595, it was proposed to
associate the bentonite with a polyacrylamide of an essentially
linear
2
nature. Th:s process met with competition from systems that were
easier to i.se yet performed just as well. Moreover, even with the
current lii.ear polyacrylamides, the retention capacity is still
insufficiei.t .
In thE document EP-A-0 017 353, it was proposed, for the
retention cf low-filler pulps (less than 5jk fillers), to
associate the bentonite with a nonionic to slightly anionic
linear copclyacrylamide. This process has not been very widely
used, sincE these polymers perform relatively poorly in terms of
retention, especially that of pulps containing fillers, no doubt
as a result of inaufficient synergy between these copolymers and
bentonite, which does not have much of a tendency to recoagulate.
1.5 In the document EP-A-0-235 893, it was proposed to use
essentiall} linear cationic polyacrylamides having molecular
weights of greater than one million, of thirty million and
higher. This resulte in the obtainment-of a retention effect that
is satisfactory, but is still deemed inadequate in the
papermaking application; since the use of bentonite causes
problems during the subsequent treatment of the effluents issuing
from the ma::hine, users select this system on].y if there are
significant advantages.
In the notes presented at the lecture given in Seattle on
October 11-L3, 1989, published under the title "Supercoagulation
in the cont:ol of wet end chemistry by synthetic polymer and
activated b;ntonite," R. Rajasvixta described the mechanism of
-supercoagulition of activated bentonite in the presencd of a
cationic po_yacrylamide, without specifying its exact nature.
This proces, has the same drawbacks as above.
Lastly European Patent 0 574 335 produced an impox-tant
improvement by proposing the use branched polymers (particularly
polyacrylam,des) in powder form.
CA 02334196 2007-06-21
85750-14 3
The invention eliminates the drawbacks mentioned above.
According to one aspect of the invention, there is provided
a process for manufacturing a sheet of paper or paperboard having
improved retention and drainage properties, of the type which
uses a dual system of an acrylic polymer and bentonite or a
possibly treated kaolin as the primary and secondary retention
agents, respectively, the introductions of which are separated by
a stage for shearing the suspension or fibrous mass or paper
pulp, characterized in that said polymer is a branched acrylic
(co)polymer prepared in the form of a reverse phase water-in-oil
emulsion, used either in emulsion reversed in water or in a
solution of the powder obtained by drying the emulsion, said
branched acrylic (co)polymer being introduced into the paper pulp
at a concentration of 0.03 to one per mill (0.03 to 1 %o) by
weight or 30 to 1,000 g/t, of the dry weight of the fibrous
suspension of paper pulp, wherein its UL viscosity is > 3.
Its object is to obtain an improved process of the type in
question, which is comprised of adding to the suspension or
fibrous mass or paper pulp to be flocculated, as the main
retention aid, an agent consisting of or comprising a branched
polyacrylamide which is characterized in that it has been
prepared in reverse phase or water-in-oil emulsion, and bentonite
as the second retention aid (a so-called "dual" system of the
type also known as "microparticulate").
The phrase "exists in reverse phase emulsion" or similar
expressions related to the polymer used (i.e., injected or
introduced into the pulp to be flocculated) according to the
invention, will be understood by one skilled in the art to
designate the reverse phase water-in-oil emulsion that is
dissolved in water before its injection or its introduction into
the mass or pulp to be flocculated (this dissolution in water
results in what is known as the "reversal" of the initial reverse
phase water-in-oil emulsion; these processes are well known to
CA 02334196 2007-06-21
85750-14 3a
one skilled in the art).
The additions of the polymer and the bentonite are separated
by a shearing stage, for example at the level of the mixing pump
known as a "fan pump." In this field, the reader is referred to
the specification of US patent 4,753,710, as well as to a vast
body of prior art related to the addition point of the retention
aid relative to the shearing stages existing in the machine,
including US patent 3,052,595; Unbehend, TAPPI Vol. 59, No. 10,
October, 1976; Luner, 1984 Papermakers Conference or TAPPI,
April, 1984, pp. 95-99; Sharpe, Merck and Co., Inc., Rahway, NJ,
USA, around 1980, Chapter 5, "Polyelectrolyte Retention Aids";
Britt, TAPPI Vol. 56, October 1973, p. 46 ff.; and Waech, TAPPI,
March, 1983, p. 137; or even US patent 4,388,150 (Eka Nobel).
4
The rEader is also referred to US patent 4,753,710 for all
of the generalities related to paper production, the uaual
additives i:sed, and similar details.
It is possible to replace the bentonite, as the secondary
retention ai.d, with a kaolin, as described in the Applicant's
French patezt application 95 13051, this kaolin preferably being
pretreated +vith a polyelectralyte. One skilled in the art can=
refer to this French patent application 95 13051.
This p~ocess makes it possible to obtain a distinctly
improved re:ention of fines and fillers without a reverse effect.
An addition3l characteristic of this improvement is that the
drairiage pr)perties are improved.
The br=inched polyacrylamide (or more generally the branched
(co)polymer is introduced into the suspension, in a distinctly
preferred wiLy, in the form of a reverse phase water-in-ail
emulsion at a rate of 0.03 to one per mill (0.03 to I%o, or 30
to 1,000 g/1) by weight of active material (polymer) relative to
the dry weic=ht of the fibrous suspension, preferably 0.15 to 0.5
per nlill, oi= 150 to 500 g/t.
In a wcy that is known to one skilled in the art, the
reverse pha:e emulsion polymer is diluted in water and inverted
(solubized) by this dilution before its introduction, as
described al ove .
This sElection of the reverse phase emulsion form'makes it
possible, in the papermaking application for the retention of
fillers and E%nes, to reach a level of performance unequalled up
to now. MoreDver, the utilization of branched polymers make$ it
possible to Dbtain a better retention of the bentonite in the
sheet, as de3cribed in the above-mentioned Europeazi patent 0 574
335, and thu3 to limit its negative effects on the subsequent
5
treatment c,f the effluents issuing from the machine. Furthermore,
the choice of this branched polyacrylamide increases the fixation
capat;-ty oT the th-e , corraequentl
a synergy, and hence a recoagulation, which reduces the bentonite
content in the white water.
It is understood that it is essential according to the
invention that the polymer be prepared by means of a reverse
phase oil-in-water emulsion polymerization. However, this polymer
can then be used (i.e., injected or introduced into the mass or
pulp to be Elocculated) either zn the form - preferably - of this
reverse phase emulsion after its dissolution in water, or in the
form of a p~wder obtained by drying (especially drying by means
of "spray d--ying") the reverse phase emulsion from the
polymerization, and then redissolving this powder in water, for
example at i concentration on the order of 5 g of active
polymer/lit:r, the solution thus obtained then being injected=
into the pu.p at substantially the same polymer dosages.
Advantitgeously, in practice, the branched (co)polyacrylamide
is a cation:.c copolymer of acrylamide and of an unaaturated
cationic et].ylenic monomer, chosen from. the group comprising
dimethylami,i,oethyl acrylate (ADAME), dimethylaminoethyl
methacrylate (MADAME), quaternized or salified by different acids
and quateriiizing agents, benzyl chloride, methyl chloride, alkyl
or aryl chicride, dimethyl sulfate, diallyldimethylammonium
chloride (DFDMAC), acrylamidopropyltrimethylammonium chloride
(APTAC), anc methacrylamidopropyltrimethylammonium chloride
(MAPTAC).
In a knDwn way, this copolymer is branched by a branching
agent consti:uted by a compound having at least two reagent
groups chosei from the group comprising the double bonds,
aldehyde bon3s, or epoxy bonds. These compounds are well known
15 and are desc=ibed, for example, in the document EP-A-0 374 458
6
(see also i.he Applicant's document FR-A-2 589 145).
As is known, a "branched" polymer is a polymer that has in
the chain },ranches, groups or branchings globally disposed in one
plane and i.ot in the three directions, unlike a"cross -linked"
polymer; branched polymers of this type, of high molecular
weight, arE well known as flocculating agents. These branched
polyacrylar.ides are distinguished from the cross-linked
polyacrylan.ides by the fact that in the latter, the groups are
disposed ttree dimensionally so as to lead to practically
inso:iuble Froducta of infinite molecular weight.
The bzanching can be carried out preferably during (ox
possibly after) the polymerization, for example by reaction of
two solublE polymers having counter-ions, or by reaction on
formaldehyc or a polyvalent metal compound. Often, the branching
is carried out during the polymerization by the addition of a
branching agent, and this method is clearly preferred according
to the inve:ition. These processes for polymerization with
branching are well known.
The branching agents that can be incorporated compriae ionic
branching a;ents such aa polyvalernt metal salts, formaldehyde;
glyoxal, or even, preferably, covalent cxoss linkers that will
copolymeriz: with the monomers, preferably monomers with
diethylenic unsaturation (like the family of diacrylate esters
such ae the diacrylates of polyethylene glycol PEG) or
polyethylen_c unsaturation, of the type classically used for the
cross-linki:ig of water-soluble polymers, and particula=ly
methylenebi,sacrylamide (MBA), or any of the other known acrylic
branching ai [enta .
These :igents are often identical to the croes linkers, but
cross-linki]Lg can be avoided when desiring to obtain a polymer
that is braiiched but not cross-linked, by optimizing
polymerizat:on conditions such as the concentration of the
7
polymerization, type and quantity of transfer agent, temperature,
type and qt:ality of initiators, and the like.
In practice, the branching agent is methylenebisacrylamide
(MHA), intzDduced at a rate of five to two hundred (5 to 200)
moles per uillion moles of monomers, preferably 5 to 50.
Advantageously, the quantity of branched polyacrylamide
introduced into the suspension to be flocculated is between
thirty and Dne thousand grams of active polymer/ton of dry pulp
(30 and 1,000 g/t), or between 0.03 per mill and one per mill,
preferably 150 to 50o g/t; it was observed that if the quantity
is lower th3n 0.03 %o (0.03 per mill), no significant retention
is obtained; likewi.ee, if this quantity exceeds 1%o (1 per
mill), no proportional improvement is observed; however, unlike
the linear :-ationic polyacrylamides, as described in the
documents E?-A-0 017 353 and EP 0 235 893 mentioned in the
preaznble, tzere is no observed reverse dispersion effect by
reci.rculati Dzz in the closed circuits of the excess polymer not
retained in the sheet. Preferably, the quantity of branched
polyacrylamide introduced is between 0.15 and 0.5 per mill (0.15
and 0.5 %o) of the quantity of dry pulp=, or between 150 g/t and
500 g/t.
As sta:ed above, it is important that the branched polymer
be prepared in reverse phase (water-in-oil) emulsion form in
order to aciieve the improvement of the invention. Emulsions of
this type aid the process for preparing them are well known to
one skilled in the art.
This a)proaCh was condemned in the above-mentioned European
patent 0 57-: 335, in which it was indicated that if a branched
polymer is =tsed in emulsion, the indispensable pre$ence of
surfactants in these emulsions promotes the.formation of foams
during the production of the paper and the appearance of
8
disparities in the physical properties of the finished paper
(modi:ficatiDn of the absorbency in the places where part of the
oil phase cF the emulsion is retained in the sheet).
TherefDre, it was not obvious to consider a fortiori the
reverse phase water-in-oil emulsions whose oil content is clearly
high.
The invention was even more difficult to achieve in that it
was importazt to stay within the field of branched polymer$ and
not to cros3 over to the field of cross-linked polymers. It is
known that --echnically, especially on an industrial production
scale, the :)orderline between the two areas is very easily
cxoased, in a way that is, moreover, irreversible. Since the
branched ar!a is very limited, the difficulty of developing the
invention ia considerable, and the Applicant desexves credit for
undertaking to use of this technology in the field of paper
production, which poses particular problems and has strict
quality xeqiirements.
The ri;k of failure, which may explain the fact that this
technology 'iad not been used, was even greater in that cross-
linked emu7.sions are not known to provide any particular
advantage i:i paper.
in comparison with the linear polymers, the branched
polymers in powder form of the above-mentioned European patent 0
574 335 had already made substantial progress relative to the
properties :nd the paper production process. The improvement was
on the orde:= of 20 to 40 t depending on the properties.
With t):e present branched emulsions, an improvement on the
order of 50 to 60 t is obtained, which would not have been
foreseeable since, on the contrary, it wae known that the cro9s-
linked prodi.cts did not work.
.9
Accorcing to the invention, in a preterxed but non-limiting
way, a"mocerately branched" polymer is used, for example with 10
ppm of brar.ching agent relative to the active materiaJ._
As alieady indicated above, the polymer can be used either
in the forn of its synthetic reverse-phase emulsion, dissolved or
"inverted~ in water, or in the form of the solution in water of
the powder Dbta.zned by dryi,ng said synthetic emulsion, :
part:icularly by means of spray-drying;. Spray-drying is a process
that is al.eD known to one skilled in the art. The reader is
referred tc the tests below in order to verify that the results
are comparaz)le.
Bentonite, also known as "amectic swelling clay," from the
montmorillo-iite family, is well known and there is no need to
desc:ribe it in detail here; these compounds, formed'of
microcrystaLlites, comprise surface sites having a high cation
exchange ca:)acity capable of retaining water (see for example the
document US-A-4 305 781, which corresponds to the document EP-A-0
017 353 men:ioned above, and FR-A-2 283 102),
Preferibly, a semisodic bentonite is used, which is
introduced just upstream from the headbox, at a rate of 0.1 to
0.5 percent (0.1 to 0.5$) of the dry weight of the fibrous
suspension.
As a f.ller, it is possible to use kaolins, GCC or ground
CaCO3, preci pitated CaCQ3 or PCC, and the like.
The br,Lnched polymer in reverse phase emulsion according to
the inventio~n is injected or introduced prior to a shearing stage
into the paper pulp (or fibrous mass to be flocculated;, which is
more or lese; diluted*according to the,experience of one skilled
in the art, and generally into the diluted paper pulp or "thin
stock," i.e a pulp diluted to about D.7 to 1.5 % solid matter
such as cel:ulose fibers, possible fillers, and the various
additives ccmmonly used in papermaking.
10
Accorcing to a variant of the invention with fractionated
introducticn, some of the branched polymer in emulsion according
to the invention is introduced at the;level of the stage for
preparing tze "thick stock" with about 5t or more solid matter,
or even at :he level of the preparation of the thick stock before
a shearing atage.
The foLlowing examples illustrate the invention without
limiting ita scope.
LO B.7LAMPLE ].
Production of a branched Polvmer in the form of a reverse phaSe
water-in-oi. _ emulaion
L5 In a rF=actor A, the constituentsbf the organic phase of the
emulsion to be synthesized are mixed at the ambient temperature.
a) Organic phase
- 252 g of lxxsol. D100 M1
- 18 g of Slan 80
20 - 4 g of Hyxermer 2296
b) In a beaker B, the aqueous phase of'the emulsion to be
produced is prepared by mixing:
- 385 g of a--rylamide at 50%
- 73 g of et:iyl acrylate trimethyl ammonium chloride 80%
>_5 - 268 g of w 3ter
- 0.5 g of m:thylenebisacrylamide at 0.25%
- 0.75 ml of sodium bromate at 50 g l-1"
- 20 ppm of aodium hypophosphite relative to the active material
- 0.29 ml of Versenex at 200 g 1"
;0 The con :ents of B are mixed into A under agitation. After =
the mixing o: the phases, the emulsion;is sheared in the mixer
for 1 minute in order to create the revdrse ph&se emulsion. The
emulsion is t.hen degassed by means of a nitrogen bubbling; then
after 20 mini.tes the gradual addition o.f the metabisulfite Causes
5 the initiaticn followed by the polymeri;zation.
11
Crice the reaction is finished, a"buin out" (treatment
with the metabisulfite) is carried out, in orde'r to reduce the
fzee monomer content.
The etrzlsion ia then incorporated with it's inverting
surfactant in order to subsequently release the polymer in the
aqueous phaae. zt is necessary to int'roduce 2 to 2.4% ethoxylated
alcohol_ T17: standard Brookfield viscosity of said polXmer is
4.36 cps (viscosity measured at 0.1% in a 1 M NaCl solution at
25 C at gix=y rpm).
In acc:)rdance with a variation of the MBA-content from 5 to
ppm, the results in terms of UL viscosity are the following:
Table of Eximple 1:
Test 4BA NaH2POz, UL IR (1) IVR (2) State
?pm ppm (*) Viscosity N) (1)
R 52 5 20 4.56 12.8 0 Branched
R 102 10 20 3.74 28.9 0 Branched
SD 102 LO 20 3.70 26 0 Branched
X 104 LO 40 2.31 45 50' Cross-
J. inked
X 204 !0 40 2.61 54.8 50 Cross-
linked
EM 140CT ) 15 4.5 0; 0 Linear
EM 140L 30 3.82 a 0. Linear
EM 14 OLI3 11 40 3.16 0' <, 0 Linear
:0 100 Cross-
EM 140BD 0 1.85 8!
~linked
FO 4198 ! 20 3.2 5 <10 Branched
FO 4198 : a k ranched powder containing 2;0 ppm tr,azlsfer agent and 5
ppm branchirg agent.
{*} , ac dium hypophosphite, tran$fex agent
= , p
r
12
(1) . :.onic regain in
(2) ntrinsic viscosity regain in 96
EM140CT: z. standard emulsion of very,high molecular weight
=
containing no branching age'nt
EM 140L: standard emulsion of high:~molecul;ar weight containing
ro branching agent
EM140LH: Fn emulsion of average molecular we~ight containing no
Yranching agent
EM140HD: a cross-linked emulsion containing no transfer agent
E:nd 5 ppm cross linker
f
SD 102: the emulsion R 102 dried by; spray-drying, and the
r~wder obtained dissolved in water to 5 g of active
FDlymer/liter
~..
It is :ioted that the linear prod~cts do Zot develop any
ionic regaii IR, and their intrinsic vi . seosity,IV decreases under
;=
the effect ~f an intense shearing (two'of thelIV values are
negative); :he branched products in erl'x:ulsion develop an ionic
regain IR, 3ut no YV (values <= 0); the cross=linked products
develop a h.gh ionic regain and a very,'high Iv'regain.
Definitions of the ionic regains and itiitrins],c viscosity regains:
Ionic regain IR = (X-Y) /Y x 100
with X . ionicity after shearing in meq/;g,
Y ionicity before shearirig in meci/g.
Intrinsic viscosity regain IVR= (Vl-V2?-/V2 x.100
with Vl intrinsic'viscosity aftr sheari ng in dl/g
i
V2 intrinsic viscosity before shearing in dl/g
~=
Some of the emulsions cited above( will beAhe subjects of a
study of effectiveness in retention an~_ drainag,e in an automated
'
sheet formex at the Center for Paper Technology.
r , i.
ci
Procedure :'or testing the emulsions
Pulp used=
mixture of 70t bleached hardwood kraft KF
10% b:.eached softwood kraft KR
20t mE:chanical pulp PM
20t n;.tural calcium carbonate.
t:izing in a neutral medium lwi.th 2% of an alkyl ketene
c.imer emulsion.
The pi.lp used is diluted to a cmsistency of 1.5%. A sample
of 2.24 dr,' g of pulp, or 149 g of pu' p at 150%, is taken, then
diluted to 0.4% with clear water.
}
The 5E0 ml volume is introduced anto the-plexiglass cylinder
of the autcmated sheet former, and thre sequence is begun.
s, .
- t 0 s, start of agitation at 41500 rpm.
,
- t 10 s, addition of the polyme 3.
- t 60 8, automatic reduction tol'1000 rpm and, if necessary,
addition of the benton-Xte.
- t 75 s, stopping of the agitatlion, formation of the sheet
with vacuum under the uire, followed by
reclamation of the white water.
The fcllowing operations are then carried out:
- measuxement of the turbidity of theswater under the wire.
- dilution of a beaker of thick stock;;for a new sheet with the
reclaimed uater under the wire.
- drying of the so-called 1st pass sheet.
- start of a new sequence for producing the so-called 2nd pass
sheet.
~. ,
After 3 passes, the products to be tested are changed.
The following analyses are then performed:
- measuremezt of the matter in suspension in the water under the
14
wire (TAPP; standard: T 656 cm/83)
- measuremont of the ash in the sheee (TAPPI standard: T 211 om-
93)
- measux=emE nt of turbidity 301 after the fibers are deposited in
order to lf arn the state of the ionicdl medium.
- measuremEnt of the degree of drainability of the pulp with'a
Canadian Standard Freeness (CSF; TApPIT standar'd T 227 om - 94).
Notes for 7 ables (Y) and (I1) below:
X = Eo-ca].led first-pass measur'oment
R1 = :o-called second pass-measu~ement (lst recycling)
R2 = Eo-called third pass measurment (2nd recycling)
Ash% I by weight of ash retainedk(= filler retention) in the
sheet/weigYt of the sheet.
p
Comments oA the results : see Tables (I) and(lT) belovv relative
~
to Rxaumle 1, and Fic.Is 1 throuq~h 10, ilwhich represent the
corresoondi acr histoarams
The cr)ss-linked polymers have no advantage as to the
flocculatio z and the retention of fin's and fillers in spite of
the high ra:e of shear applied duringi he process to the fibrous
mass (and n.)t applied to the polymer i self), in this case 1,500
G =
rpm, which -s characteristic of this t~ e of micropaxticulate
retention s.-stem. They show a poor ca~ure of fillers and
colloidal mLtter, since no reduction turbidity is observed_
The cottbination with bentonite do s not significantly
improve the effectiveness in terms of etention and only sli.ghtly
improves thE effectiveness in terms of~ drainage.
As for the linear polymer, its b avior followa the tendency
to improve the retention of fillers fines.
CA 02334196 2007-06-21
85750-14 15
The combination according to the invention of a branched
polymer in reverse phase emulsion and bentonite provides a net
gain in filler retention and in total retention, and is revealed
to be superior to the known linear polymer/bentonite system.
The coagulation capacity is better for a branched polymer in
emulsion, which translates into an excellent reduction in the
turbidity at 30' (30 min.).
The R 52 test and the R 102 test show that the invention
makes it possible to obtain branched products having UL
viscosities higher than those accessible through gel
polymerization as described in European patent 0 574 335. Any
attempt to reach such highly advantageous UL viscosity values
using a gel polymerization process with drying into a powder
would result in a product that was totally insoluble and
therefore totally unusable in the industry.
The SD 102 test shows that the polymer used in the form of a
solution in water of the powder obtained by drying the reverse
phase emulsion from the synthesis of the polymer behaves like the
polymer used in the form of the solution in water of said
synthetic reverse phase emulsion. In particular, no degradation
of the polymer is observed during the stage for drying by means
of spray-drying.
It is useful to compare the R 52 test to the FO 4198 test
(powder), since the polymers have the same chemistry, hence the
same cationicity, and the same % of MBA, while the R52 of the
invention is far superior to the powder in terms of drainage and
retention (96.3 as compared to 83.6); compare also the turbidity
in NTU after 30 minutes, 32 as compared to 75 NTU units.
Such UL viscosity values specifically result in
substantially improved drainage.
16
The irvention also relates to a novel retention aid fox' the
production of a sheet of paper, paperboard or the like, which is
comprised cf a branched acrylic (co)polymer as described above,
in reverse phase emulsion, which is characterized in that its UL
viscosity is > 3, or > 3.5 or > 4. Said agent can be used either
in emulsior, inverted in water, or in a solution of the powder
obtained by drying the emulsion, as described above.
EXAMPLE 2
Production af a branched acrylama.dopropvltrimethvlaumloni.um
chloride (PTAC) baeed polymer in the form of a reverse phase
oil-in-water emulsion:
In a r~actor A, the constituents of the organic phase of the
emulsion to be synthesized are mixed at the ambient temperature.
a) Organic :)hase
- 252 g of sxxsol D100
- 18 g of S: )an 80
- 4 g of Hy, )ermer 2296
b) In a bea]:er B, the phase of the emuleion to be produced is
prepared by mixing:
- 378 g of i.crylamide at 50%
~ 102.2 g oi acrylamidopropyltrimethylamonium chloride (60t)
- 245.7 g oi water
- 0.5 g of r.ethylenebisacrylamide at 0.25%
0.75 ml oi sodium bromate at 50 g/l 30 - 20 ppm of sodium hypophosphite
relative to the active material
- 0.29 mJ, of Versenex at 200 g/1
The cortents of B are mixed into A under agitation. After
the mixing cf the phases, the emulsion is sheared in the mixer.
for 1 minutE in order to create the reverse-phase emulsion. The
17
emulsion is then degassed by means of a nitrogen bubbling; then
after 20 mizutes, the gradual addition of the metabisulfite
causes the initiation followed by the polymerization.
Once t3e reaction is finished, a "burn out" is carried out
in order to reduce the free monomer content.
The emi].sion is then incorporated with its inverting
surfactant _n order to subsequently free the polymer in the
aqueous pha :e .
Table of Ex. op1e 2:
Test M3.A NaI12PO UL IR (1) IVR (2) State
p )m ppm Viscosity (t) (~)
M 52 5 20 4.20 14.2 a Branched
M 102 1) 20 3.34 21.3 0 Branched
XM 104 1) 40 2. Z1 37 50 Cross-
linked
XM 204 2) 40 1-94 58 55 Cross-
linked
EK 190 0 15 4.35 0. 0 Linear
EK 190 5 0 1.85 78 60 Cross-
BD linked =
EK 190: a standard emulsion of a copolymer of acrylamide and
acrylamidopxopyltrimethylammonium chloride, linear.
Procedure fc r testi.ncr the emulsions (identical to that of Examp7.e 1)
Comments on the resuZts: see Table (TZZ) below relative to
Example 2, a id F,iga . 11 throuc[h 20, which represent the
corxesyondin I histacxrams
18
The rEsults invite the same comments as those of Example 1
and confirn the great advantage of the preaent invention.
The irvention also relates to the novel xetention aids
described zbove, characterized in that they consist of, or
comprise, tt least one branched (co)polymer of the type
described, prepared in reverse phase emulsion, intended to
cooperate hith a secondary retention aid after an intermediate
stage for --hearing the paper pulp, as well as to the processes
for producing sheets of paper, paperboard or the like using the
agents acccrding to the invention or the process according to the
invention, and the sheets of paper, paperboard and the like thus
obtained.
Said agent can be used either in emulsion inverted in water,
or in a solition of the powder obtained by drying the emulsion,
as describe3 above.
CA 02334196 2002-03-20
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