[0001] This invention relates to papermaking and more specifically to a process for the
production of paper in which cationic and anionic polymers having aromatic groups
are added to a papermaking stock. The process provides improved drainage and retention.
Background
[0002] In the papermaking art, an aqueous suspension containing celllulosic fibres, and
optional filers and additives, referred to as stock, is fed into a headbox which ejects
the stock onto a forming were. Water is drained from the stock through the forming
wire so that a wet web of paper is formed on the wire, and the web is further dewatered
and dried in the drying section of the paper machine. The obtained water, usually
referred to as white water and containing fine particles such as fine fibres, fillers
and additives, is usually recycled in the papermaking process. Drainage and retention
aids are conventionally introduced into the stock in order to facilitate drainage
and increase absorption of fine particles onto the cellulose fibres so that they are
retained with the fibres. A wide variety of drainage and retention aids are known
in the art, for example anionic, non-ionic, cationic and amphoteric organic polymers,
anionic and cationic Inorganic materials, and many combinations thereof.
[0003] International Patent Application Publication Nos.
WO 99/55964 and
WO 99/55965 disclose the use of drainage and retention aids comprising cationic organic polymers
having aromatic groups, The cationic organic polymers can be used alone or in combination
with various anionic materials such as, for example, anionic organic and inorganic
condensation polymers, e.g. sulphonated melanine-formaldehyde and silica-based particles.
[0004] GB 1,177,512 relates to an improved papermaking process.
US 6,001,166 discloses an aqueous alkyldiketene dispersion.
WO 98/33979 discloses an aqueous dispersion containing a cellulose-reactive sizing agent.
[0005] It would be advantageous to be able to provide a papermaking process with improved
drainage and retention. It would also be advantageous to be able to provide drainage
and retention aids comprising cationic organic polymers and anionic polymers with
Improved drainage and retention performance.
The Invention
[0006] According to the present invention it has been found that improved drainage and/or
retention can be obtained by using drainage and retention aids comprising a cationic
organic polymer having an aromatic group and an anionic polymer having an aromatic
group. More specifically, the present invention relates to a process for the production
of paper from an aqueous suspension containing cellulosic fibres, and optional fillers,
which comprises separately adding to the suspension a cationic organic polymer having
an aromatic group the cationic polymer being a cationic polysaccharide and an anionic
polymer having an aromatic group, the anionic polymer being selected from step-growth
polymers, polysaccharides, and naturally occurring aromatic polyniers and modifications
thereof, forming and draining the suspension on a wire, with the proviso that if the
anionic polymer is selected from step-growth polymers, it is not an anionic melamine-sulphonic
acid condensation polymer. The invention further relates to a process for the production
of paper from an aqueous suspension containing cellulosic fibres, and optional filers,
which comprises separatety adding to the suspension a cationic organic polymer having
an aromatic group the cationic polymer being a cationic polysaccharide and an anionic
polymer having an aromatic group, forming and draining the suspension on a wire, with
the proviso that the anionic polymer is not an antonic polystyrene sulphonate or anionic
melamine-sulphonic acid condensation polymer. The invention thus relates to a process
as further defined in the claims.
[0007] The term "drainage and retention aids", as used herein, refers to two or more components
which, when added to an aqueous cellulosic suspension, give better drainage and/or
retention than is obtained when not adding the said two or more components.
[0008] The present invention results in improved drainage and/or retention In the production
of paper from all types of stocks, in particular stocks having high contents of salts
(high conductivity) and colloidal substances, and/or in papermaking processes with
a high degree of white water closure, i.e. extensive white water recycling and limited
fresh water supply. Hereby the present invention makes it possible to increase the
speed of the paper machine and to use a lower dosage of additives to give a corresponding
drainage and/or retention effect, thereby leading to an improved papermaking process
and economic benefits. The present invention also provides paper with improved dry
strength.
[0009] The cationic organic polymer having an aromatic group according to the present invention
can be derived from natural or synthetic sources, and it can be linear, branched or
cross-linked. Preferably the cationic polymer is weter-soluble or water-dispersable.
Examples of suitable cationic polymers include cationic polysaccharides, e.g. starches,
guar gums, celluloses, chitins, chitosans, glycans, galactans, glucans, xanthan gums,
pectins, mannans, dextrins, preferably starches and guar gums, suitable starches including
potato, corn, wheat, tapioca, rice, waxy maize, barley, etc.; cationic synthetic organic
polymers such as cationic chain-growth polymers, e.g. cationic vinyl addition polymers
like acrylate-, acrylamide-, vinylamine- and vinylamide-based polymers, and cationic
step-growth polymers, e.g. cationic polyurethanes. Cationic starches and cationic
acrylamide-based polymers having an aromatic group are particularly preferred cationic
polymers.
[0010] The cationic organic polymer according to the invention has one or more aromatic
groups and the aromatic groups can be of the same or different types. The aromatic
group of the cationic organic polymer can be present In the polymer backbone the cationic
polymer being a cationic polysaccharide
[0011] (main chain) or in a substituent group that is attached to the polymer backbone,
preferably in a substituent group. Examples of suitable aromatic groups include aryl,
aralkyl and alkaryl groups, e.g. phenyl, phenylene, naphthyl, phenylene, xylylene,
benzyl and phenylethyl; nitrogen-containing aromatic (aryl) groups, e.g. pyridinium
and quinolinium, as well as derivatives of these groups, preferably benzyl. Examples
of cationically charged groups that can be present in the cationic polymer as well
as in monomers used for preparing the cationic polymer include quaternary ammonium
groups, tertiary amino groups and acid addition salts thereof.
[0012] According to a preferred embodiment of this invention, the cationic organic polymer
having an aromatic group is a polysaccharide represented by the general structural
formula (I):
wherein P is a residue of a polysaccharide; A
1 is a group attaching N to the polysaccharide residue, suitably a chain of atoms comprising
C and H atoms, and optionally O and/or N atoms, usually an alkylene group with from
2 to 18 and suitably 2 to 8 carbon atoms, optionally interrupted or substituted by
one or more heteroatoms, e.g. O or N, e.g. an alkyleneoxy group or hydroxy propylene
group (-CH
2-CH(OH)-CH
2-); R, and R
2 are each H or, preferably, a hydrocarbon group, suitably alkyl, having from 1 to
3 carbon atoms, preferably 1 to 2 carbon atoms; Q is a substituent containing an aromatic
group, suitably a phenyl or substituted phenyl group, which can be attached to the
nitrogen by means of an alkylene group usually having from 1 to 3 carbon atoms, suitably
1 to 2 carbon atoms, and preferably Q is a benzyl group (-CH
2-C
6H
5); n is an integer, usually from about 2 to about 300,000, suitably from 5 to 200,000
and preferably from 6 to 125,000 or, alternatively, R
1, R
2 and Q together with N form a aromatic group containing from 5 to 12 carbon atoms;
and X
- is an anionic counterion, usually a halide like chloride. Suitable polysaccharides
represented by the general formula (I) include those mentioned above. Cationic polysaccharides
according to the invention may also contain anionic groups, preferably in a minor
amount. Such anionic groups may be introduced in the polysaccharide by means of chemical
treatment or be present in the native polysaccharide.
[0013] According to another preferred embodiment of this invention, the cationic organic
polymer having an aromatic group is a chain-growth polymer. The term "chain-growth
polymer", as used herein, refers to a polymer obtained by chain-growth polymerization,
also being referred to as chain reaction polymer and chain reaction polymerization,
respectively. Examples of suitable chain-growth polymers include vinyl addition polymers
prepared by polymerization of one or more monomers having a vinyl group or ethylenically
unsaturated bond, for example a polymer obtained by polymerizing a cationic monomer
or a monomer mixture comprising a cationic monomer represented by the general structural
formula (II):
wherein R
3 is H or CH
3; R
1 and R
2 are each H or, preferably, a hydrocarbon group, suitably alkyl, having from 1 to
3 carbon atoms, preferably 1 to 2 carbon atoms; A
2 is O or NH; B
2 is an alkyl or alkylene group having from 2 to 8 carbon atoms, suitably from 2 to
4 carbon atoms, or a hydroxy propylene group; Q is a substituent containing an aromatic
group, suitably a phenyl or substituted phenyl group, which can be attached to the
nitrogen by means of an alkylene group usually having from 1 to 3 carbon atoms, suitably
1 to 2 carbon atoms, and preferably Q is a benzyl group (-CH
2-C
6H
5); and X
- is an anionic counterion, usually a halide like chloride.
[0014] Examples of suitable monomers represented by the general formula (II) include quaternary
monomers obtained by treating dialkylaminoalkyl (meth)acrylates, e.g. dimethylaminoethyl
(meth)acrylate, diethylaminoethyl (meth)acrylate and dimethylaminohydroxy-propyl (meth)acrylate,
and dialkylaminoalkyl (meth)acrylamides, e.g. dimethylaminoethyl (meth)acrylamide,
diethylaminoethyl (meth)acrylamide, dimethylaminopropyl (meth)-acrylamide, and diethylaminopropyl
(meth)acrylamide, with benzyl chloride. Preferred cationic monomers of the general
formula (I) include dimethylaminoethylacrylate benzyl chloride quaternary salt and
dimethylaminoethylmethacrylate benzyl chloride quaternary salt. The monomer of formula
(II) can be copolymerized with one or more non-ionic, cationic and/or anionic monomers.
Suitable copolymerizable non-ionic monomers include (meth)acrylamide; acrylamide-based
monomers like N-alkyl (meth)acrylamides, N,N-dialkyl (meth)acrylamides and dialkylaminoalkyl
(meth)acrylamides, acrylate-based monomers like dialkylaminoalkyl (meth)acrylates,
and vinylamides. Suitable copolymerizable cationic monomers include acid addition
salts and quaternary salts of dimethylaminoethyl (meth)acrylate and diallyldimethylammonium
chloride. The cationic organic polymer may also contain anionic groups, preferably
in a minor amount. Suitable copolymerizable anionic monomers include acrylic acid,
methacrylic acid and various sulphonated vinylic monomers such as styrenesulphonate.
Preferred copolymerizable monomers include acrylamide and methacrylamide, i.e. (meth)acrylamide,
and the cationic or amphoteric organic polymer is preferably an acrylamide-based polymer.
[0015] Cationic vinyl addition polymers according to this invention can be prepared from
a monomer mixture generally comprising from 1 to 99 mole%, suitably from 2 to 50 mole%
and preferably from 5 to 20 mole% of cationic monomer having an aromatic group and
from 99 to 1 mole%, suitably from 98 to 50 mole%, and preferably from 95 to 80 mole%
of other copolymerizable monomers which preferably comprises acrylamide or methacrylamide
((meth)acrylamide), the monomer mixture suitably comprising from 98 to 50 mole% and
preferably from 95 to 80 mole% of (meth)acrylamide, the sum of percentages being 100.
[0016] Examples of suitable cationic step-growth polymers according to the invention include
cationic polyurethanes which can be prepared from a monomer mixture comprising aromatic
isocyanates and/or aromatic alcohols. Examples of suitable aromatic isocyanates include
diisocyanates, e.g. toluene-2,4- and 2,6-diisocyanates and diphenylmethane-4,4'-diisocyanate.
Examples of suitable aromatic alcohols include dihydric alcohols, i.e. diols, e.g.
bisphenol A, phenyl diethanol amine, glycerol monoterephthalate and trimethylolpropane
monoterephthalate. Monohydric aromatic alcohols such as phenol and derivaties thereof
may also be employed. The monomer mixture can also contain non-aromatic isocyanates
and/or alcohols, usually diisocyanates and diols, for example any of those known to
be useful in the preparation of polyurethanes. Examples of suitable monomers containing
cationic groups include cationic diols such as acid addition salts and quaternization
products of N-alkandiol dialkylamines and N-alkyl dialkanolamines like 1,2-propanediol-3-dimethylamine,
N-methyl diethanolamine, N-ethyl diethanolamine, N-propyl diethanolamine, N-n-butyl
diethanolamine and N-t-butyl diethanolamine, N-stearyl diethanolamine and N-methyl
dipropanolamine. The quaternization products can be derived from alkylating agents
like methyl chloride, dimethyl sulphate, benzyl chloride and epichlorohydrin.
[0017] The weight average molecular weight of the cationic polymer can vary within wide
limits dependent on, inter alia, the type of polymer used, and usually it is at least
about 5,000 and often at least 10,000. More often, it is above 150,000, normally above
500,000, suitably above about 700,000, preferably above about 1,000,000 and most preferably
above about 2,000,000. The upper limit is not critical; it can be about 200,000,000,
usually 150,000,000 and suitably 100,000,000.
[0018] The cationic organic polymer can have a degree of cationic substitution (DS
c) varying over a wide range dependent on, inter alia, the type of polymer used; DS
c can be from 0.005 to 1.0, usually from 0.01 to 0.5, suitably from 0.02 to 0.3, preferably
from 0.026 to 0.2; and the degree of aromatic substitution (DS
o) can be from 0.001 to 0.5, usually from 0.01 to 0.5, suitably from 0.02 to 0.3 and
preferably from 0.025 to 0.2. In case the cationic organic polymer contains anionic
groups, the degree of anionic substitution (DS
A) can be from 0 to 0.2, suitably from 0 to 0.1 and preferably from 0 to 0.05, the
cationic polymer having an overall cationic charge. Usually the charge density of
the cationic polymer Is within the range of from 0.1 to 6.0 meqv/g of dry polymer,
suitably from 0.2 to 5.0 and preferably from 0.5 to 4.0.
[0019] Examples of suitable cationic organic polymers having an aromatic group that can
be used according to the present invention include those described in international
Patent Publication Nos.
WO 99/55964,
WO 99/55965 and
WO 99/67310,
[0020] Anionic polymers having an aromatic group according to the invention can be selected
from step-growth polymers, chain-growth polymers, polysaccharides, naturally occurring
aromatic polymers and modifications thereof. The term "step-growth polymer", as used
herein, refers to a polymer obtained by step-growth polymerization, also being referred
to as step-reaction polymer and step-reaction polymerization, respectively. Preferably
the anionic polymer is selected from step-growth polymers, polysaccharides and naturally
occurring aromatic polymers and modifications thereof, most preferably step-growth
polymers. The anionic polymers according to the invention can be linear, branched
or cross-linked. Preferably the anionic polymer is water-soluble or water-dispersable.
The anionic polymer is preferably organic.
[0021] The anionic polymer according to the invention has one or more aromatic groups and
the aromatic groups can be of the same or different types. The aromatic group of the
anionic polymer can be present in the polymer backbone or in a substituent group that
is attached to the polymer backbone (main chain). Examples of suitable aromatic groups
include aryl, aralkyl and alkaryl groups and derivatives thereof, e.g. phenyl, tolyl,
naphthyl, phenylene, xylylene, benzyl, phenylethyl and derivatives of these groups.
Example of anionically charged groups that can be present in the anionic polymer as
well as in the monomers used for preparing the anionic polymer include groups carrying
an anionic charge and acid groups carrying an anionic charge when dissolved or dispersed
in water, the groups herein collectively being referred to as anionic groups, such
as phosphate, phosphonate, sulphate, sulphonic acid, sulphonate, carboxylic acid,
carboxylate, alkoxide and phenolic groups, i.e. hydroxy-substituted phenyls and naphthyls.
Groups carrying an anionic charge are usually salts of an alkall metal, alkaline earth
or ammonia.
[0022] Examples of suitable anionic step-growth polymers according to the present invention
include condensation polymers, i.e. polymers obtained by step-growth condensation
polymerization, e.g. condensates of an aldehyde such as formaldehyde with one or more
aromatic compounds containing one or more anionic groups, and optional other comonomers
useful in the condensation polymerization such as urea and melamine. Examples of suitable
aromatic compounds containing anionic groups comprises benzene and naphthalene-based
compounds containing anionic groups such as phenolic and naphtholic compounds, e.g.
phenol, naphthol, resorcinol and derivatives thereof, aromatic acids and salts thereof,
e.g. phenylic, phenolic, naphthylic and naphtholic acids and salts, usually sulphonic
acids and sulphonates, e.g. benzene sulphonic acid and sulphonate, xylen sulphonic
acid and sulphonates, naphthalene sulphonic acid and sulphonate, phenol sulphonic
acid and sulphonate. Examples of suitable anionic step-growth polymers according to
the invention include anionic benzene-based and naphthalene-based condensation polymers,
preferably naphthalene-sulphonic acid based and naphthalene-sulphonate based condensation
polymers.
[0023] Examples of further suitable anionic step-growth polymers according to the present
invention include addition polymers, i.e. polymers obtained by step-growth addition
polymerization, e.g. anionic polyurethanes which can be prepared from a monomer mixture
comprising aromatic isocyanates and/or aromatic alcohols. Examples of suitable aromatic
isocyanates include diisocyanates, e.g. toluene-2,4- and 2,6-diisocyanates and diphenylmethane-4,4'-diisocyanate.
Examples of suitable aromatic alcohols include dihydric alcohols, i.e. diols, e.g.
bisphenol A, phenyl diethanol amine, glycerol monoterephthalate and trimethylolpropane
monoterephthalate. Monohydric aromatic alcohols such as phenol and derivaties thereof
may also be employed. The monomer mixture can also contain non-aromatic isocyanates
and/or alcohols, usually diisocyanates and diols, for example any of those known to
be useful in the preparation of polyurethanes. Examples of suitable monomers containing
anionic groups include the monoester reaction products of triols, e.g. trimethylolethane,
trimethylolpropane and glycerol, with dicarboxylic acids or anhydrides thereof, e.g.
succinic acid and anhydride, terephthalic acid and anhydride, such as glycerol monosuccinate,
glycerol monoterephthalate, trimethylolpropane monosuccinate, trimethylolpropane monoterephthalate,
N,N-bis-(hydroxyethyl)-glycine, di-(hydroxymethyl)propionic acid, N,N-bis-(hydroxyethyl)-2-aminoethanesulphonic
acid, and the like, optionally and usually in combination with reaction with a base,
such as alkali metal and alkaline earth hydroxides, e.g. sodium hydroxide, ammonia
or an amine, e.g. triethylamine, thereby forming an alkali metal, alkaline earth or
ammonium counter-ion.
[0024] Examples of suitable anionic chain-growth polymers according to the invention include
anionic vinyl addition polymers obtained from a mixture of vinylic or ethylenically
unsaturated monomers comprising at least one monomer having an aromatic group and
at least one monomer having an anionic group, usually co-polymerized with non-ionic
monomers such as acrylate- and acrylamide-based monomers. Examples of suitable anionic
monomers include (meth)acrylic acid and para vinyl phenol (hydroxy styrene).
[0025] Examples of suitable anionic polysaccharides include starches, guar gums, celluloses,
chitins, chitosans, glycans, galactans, glucans, xanthan gums, pectins, mannans, dextrins,
preferably starches, guar gums and cellulose derivatives, suitable starches including
potato, com, wheat, tapioca, rice, waxy maize and barley, preferably potato. The anionic
groups in the polysaccharide can be native and/or introduced by chemical treatment.
The aromatic groups in the polysaccharide can be introduced by chemical methods known
in the art.
[0026] Naturally occurring aromatic anionic polymers and modifications thereof, i.e. modified
naturally occurring aromatic anionic polymers, according to the invention include
naturally occuring polyphenolic substances that are present in wood and organic extracts
of bark of some wood species and chemical modifications thereof, usually sulphonated
modifications thereof. The modified polymers can be obtained by chemical processes
such as, for example, sulphite pulping and kraft pulping. Examples of suitable anionic
polymers of this type include lignin-based polymers, preferably sulphonated lignins,
e.g. lignosulphonates, kraft lignin, sulphonated kraft lignin, and tannin extracts.
[0027] The weight average molecular weight of the anionic polymer can vary within wide limits
dependent on, inter alia, the type of polymer used, and usually it is at least about
500, suitably above about 2,000 and preferably above about 5,000. The upper limit
is not critical; it can be about 200,000,000, usually 150,000,000, suitably 100,000,000
and preferably 10,000,000.
[0028] The anionic polymer can have a degree of anionic substitution (DS
A) varying over a wide range dependent on, inter alia, the type of polymer used; DS
A is usually from 0.01 to 2.0, suitably from 0.02 to 1.8 and preferably from 0.025
to 1.5; and the degree of aromatic substitution (DS
Q) can be from 0.001 to 1.0, usually from 0.01 to 0.8, suitably from 0.02 to 0.7 and
preferably from 0.025 to 0.5. In case the anionic polymer contains cationic groups,
the degree of cationic substitution (DS
C) can be, for example, from 0 to 0.2, suitably from 0 to 0.1 and preferably from 0
to 0.05, the anionic polymer having an overall anionic charge. Usually the anionic
charge density of the anionic polymer is within the range of from 0.1 to 6.0 meqv/g
of dry polymer, suitably from 0.5 to 5.0 and preferably from 1.0 to 4.0.
[0030] Examples of particularly preferred combinations of anionic and cationic polymers
having aromatic groups, as defined above, according to the present invention indude
- (i) cationic polysaccharides, preferably cationic starch, and anionic step-growth
polymers, suitably anionic benzene-based and naphthatene-based condensation polymers
and anionic polyurethanes, preferably anionic naphthalene-based condensation polymers;
- (ii) cationic polysaccharides, preferably cationic starch, and naturally occuring
aromatic anionic polymers and modifiations thereof, suitably anionic lignin-based
polymers, preferably sulphonate lignins;
- (iii) cationic chain-growth polymers, suitably cationic vinyl addition polymers, preferably
cationic acrylamide-based polymers, and anionic step-growth polymers, suitably anionic
benzene-based and naphthalene-based condensation polymers and anionic polyurethanes,
preferably anionic naphthalene-based condensation polymers; and
- (iv) cationic chain-growth polymers, suitably cationic vinyl addition polymers, preferably
cationic acrylamide-based polymers, and naturally occurring aromatic anionic polymers
and modifiations thereof, suitably anionic lignin-based polymers, preferably sulphonated
lignins.
[0031] The cationic and anionic polymers according to the invention are preferably separately
added to the aqueous suspension containing cellulosic fibres, or stock, and not as
a mixture containing said polymers. Preferably the cationic and anionic polymers are
added to the stock at different points. The polymers can be added in any order. Usually
the cationic polymer is firstly added to the stock and the anionic polymer is subsequently
added, although the reverse order of addition may also be used. The polymers can be
added to the stock to be dewatered in amounts which can vary within wide limits depending
on, inter alia, type of stock, salt content, type of salts, filler content, type of
filler, point of addition, etc. Generally the polymers are added in an amount that
give better drainage and/or retention than is obtained when not adding them and usually
the cationic polymer is added to the stock prior to adding the anionic polymer. The
cationic polymer is usually added in an amount of at least 0.001%, often at least
0.005% by weight, based on dry stock substance, whereas the upper limit is usually
3% and suitably 2.0% by weight The anionic polymer is usually added in an amount of
at least 0.001 %, often at least 0.005% by weight, based on dry stock substance, whereas
the upper limit is usually 3% and suitably 1.5% by weight.
[0032] The polymers having aromatic groups according to the invention can be used in conjunction
with additional additive(s) that are beneficial to the overall drainage and/or retention
performance, thereby forming drainage and retention aids comprising three or more
components. Example of suitable stock additives of this type include anionic microparticulate
materials, e.g., silica-based particles and days of smectite type, low molecular weight
cationic organic polymers, aluminium compounds, anionic vinyl addition polymers and
combination thereof, including the compounds and the use thereof disclosed In international
Patent Application Publication Nos.
WO 99/55964 and
WO 99/55965
[0033] Low molecular weight (hereinafter LMW) cationic organic polymers that can be used
according to the invention include those commonly referred to as anionic trash catchers
(ATC). The LMW cationic organic polymer can be derived from natural or synthetic sources,
and preferably it is an LMW synthetic polymer. Suitable organic polymers of this type
include LMW highly charged cationic organic polymers such as polyamines, polyamidoamines,
polyethylaneimines, homo- and copolymers based on diallyl-dimethyl ammonium chloride,
(meth)acrylamides and (meth)acrylates. In relation to the molecular weight of the
cationic organic polymer having an aromatic group of this invention the molecular
weight of the LMW cationic organic polymer is preferably lower; it is suitably at
least 2,000 and preferably at least 10,000. The upper limit of the molecular weight
is usually about 700,000, suitably about 500,000 and usually about 200,000.
[0034] Aluminium compounds that can be used according to the invention include alum, aluminates,
aluminium chloride, aluminium nitrate and potyaluminium compounds, such as polyalumirium
chlorides, polyalumunium sulphates, polyaluminium compounds containing both chloride
and sulphate ions, polyaluminium silicate-sulphates, and mixtures thereof. The polyaluminium
compounds may also contain other anions than chloride ions, for example anions from
sulphutic acid, phosphoric acid, organic acids such as citric acid and oxalic acid.
[0035] The process of this invention is applicable to all papermaking Processes and cellulosic
suspensions, and it is particularly useful in the manufacture of paper from a stock
that has a high conductivity. In such causes, the conductivity of the stack that is
dewatered on the wire is usually at least 2.0 mS/cm, suitably at least 3.5 mS/cm,
and preferably at least 5.0 mS/cm. Conductivity can be measured by standard equipment
such as, for example, a WTW LF 539 instrument supplied by Christian Berner. The values
referred to above are suitably determined by measuring the conductivity of the cellulosic;
suspension that is fed into or present in the headbox of the paper machine or, alternatively,
by measuring the conductivity of white water obtained by dewatering the suspension.
High conductivity levels mean high contents of salts (electrolytes) which can be derived
from the materials used to form the stock, from various additives introduced into
the stock, from the fresh water supplied to the process, etc. Further, the content
of salts is usually higher in processes where white water is extensively recirculated,
which may lead to considerable accumulation of salts in the water circulating in the
process.
[0036] The present invention further encompasses papermaking processes where white water
is extensively recycled, or recirculated, i.e. with a high degree of white water closure,
for example where from 0 to 30 tons of fresh water are used per ton of dry paper produced,
usually less than 20, suitably less than 15, preferably less than 10 and notably less
than 5 tons of fresh water per ton of paper. Recycling of white water obtained in
the process suitably comprises mixing the white water with cellulosic fibres and/or
optional fillers to form a suspension to be dewatered; preferably it comprises mixing
the white water with a suspension containing cellulosic fibres, and optional fillers,
before the suspension enters the forming wire for dewatering. The white water can
be mixed with the suspension before, between, simultaneous with or after introducing
the drainage and retention aids of this invention. Fresh water can be introduced in
the process at any stage; for example, it can be mixed with cellulosic fibres in order
to form a suspension, and it can be mixed with a thick suspension containing cellulosic
fibres to dilute it so as to form a thin suspension to be dewatered, before, simultaneous
with or after mixing the suspension with white water.
[0037] Further additives which are conventional in papermaking can of course be used in
combination with the polymers according to the invention, such as, for example, dry
strength agents, wet strength agents, optical brightening agents, dyes, sizing agents
like rosin-based sizing agents and cellulose-reactive sizing agents, e.g. alkyl and
alkenyl ketene dimers, alkyl and alkenyl ketene multimers, and succinic anhydrides,
etc. The cellulosic suspension, or stock, can also contain mineral fillers of conventional
types such as, for example, kaolin, china clay, titanium dioxide, gypsum, talc and
natural and synthetic calcium carbonates such as chalk, ground marble and precipitated
calcium carbonate.
[0038] The process of this invention is used for the production of paper. The term "paper",
as used herein, of course include not only paper and the production thereof, but also
other cellulosic fibre-containing sheet or web-like products, such as for example
board and paperboard, and the production thereof. The process can be used in the production
of paper from different types of suspensions of cellulose-containing fibres and the
suspensions should suitably contain at least 25% by weight and preferably at least
50% by weight of such fibres, based on dry substance. The suspension can be based
on fibres from chemical pulp such as sulphate, sulphite and organosolv pulps, mechanical
pulp such as thermomechanical pulp, chemo-thermomechanical pulp, refiner pulp and
groundwood pulp, from both hardwood and softwood, and can also be based on recycled
fibres, optionally from de-inked pulps, and mixtures thereof.
[0039] The invention is further illustrated in the following Examples which, however, are
not intended to limit the same. Parts and % relate to parts by weight and % by weight,
respectively, unless otherwise stated.
Example 1
[0040] Cationic polymers used in the tests were purchased on the market or prepared by generally
known procedures. The cationic polysaccharides used in the tests were prepared by
reacting native potato starch with a quaternising agent according to the general procedure
described in
EP-A 0 189 935 and
WO 99/55964. The cationic polymers used in the tests, hereinafter also collectively referred
to as cationic polymer, C1 to C3 according to the invention and C1-ref to C3-ref intended
for comparison purposes, were the following:
C1: Cationic starch obtained by quarternisation of native potato starch with 3-chloro-2-hydroxypropyl
dimethyl benzyl ammonium chloride to 0.5% N.
C2: Cationic starch obtained by quarternisation of native potato starch with 3-chloro-2-hydroxypropyl
dimethyl benzyl ammonium chloride to 0.7% N.
C3: Cationic vinyl addition polymer prepared by polymerisation of acrylamide (90 mole%)
and acryloxyethyldimethylbenzylammonium chloride (10 mole%), molecular weight about
6,000,000.
C1-ref: Cationic starch obtained by quarternization of native potato starch with 2,3-epoxypropyl
trimethyl ammonium chloride to 0.8% N.
C2-ref: Cationic starch obtained by quartemization of native potato starch with 2,3-epoxypropyl
trimethyl ammonium chloride to 0.5% N.
C3-ref: Cationic vinyl addition polymer prepared by polymerisation of acrylamide (90
mole%) and acryloxyethyltrimethylammonium chloride (10 mole%), molecular weight about
6,000,000.
[0041] Anionic polymers used in the tests were purchased on the market or prepared by generally
known procedures. The anionic polymers used in the tests, hereinafter also collectively
referred to as anionic polymer, A1 to A8 according to the invention and A1-ref to
A2-ref intended for comparison purposes, were the following:
A1: Anionic polycondensate of formaldehyde with naphthalene sulphonate, molecular
weight about 20,000.
A2: Anionic polycondensate of formaldehyde with naphthalene sulphonate, molecular
weight about 110,000.
A3: Anionic polycondensate of formaldehyde with naphthalene sulphonate, molecular
weight about 40,000.
A4: Anionic polycondensate of formaldehyde with naphthalene sulphonate, molecular
weight about 210,000.
A5: Anionic polyurethane obtained by reacting glycerol monostearate with toluene diisocyanate
to form a pre-polymer containing terminal isocyanate groups which is then reacted
with dimethylol propionic acid.
A6: Anionic polyurethane obtained by reacting phenyl diethanol amine with toluene
diisocyanate to form a pre-polymer containing terminal isocyanate groups which is
then reacted with dimethylol propionic acid and N-methyl diethanol amine.
A7: Anionic sulphonated kraft lignin.
A8: Anionic lignosulphonate.
A1 -ref: Anionic melamine-formaidehyde-sulphonate polycondensate.
A2-ref: Anionic inorganic condensation polymer of silicic acid in the form of colloidal
silica particles with a particle size of 5 nm.
[0042] A low molecular weight cationic organic polymer, also referred to as ATC, which was
used in some of the tests, was available on the market and producible by generally
known procedures. The ATC was the following:
ATC: Cationic copolymer of dimethylamine, epichlorohydrin and ethylene diamine with
a molecular weight of about 50,000.
[0043] All polymers were used in the form of dilute aqueous polymer solutions:
Example 2
[0044] Drainage performance was evaluated by means of a Dynamic Drainage Analyser (DDA),
available from Akribi, Sweden, which measures the time for draining a set volume of
stock through a wire when removing a plug and applying vacuum to that side of the
wire opposite to the side on which the stock is present.
[0045] A standard stock was prepared from a furnish based on 56% by weight of peroxide bleached
TMP/SGW pulp (80/20), 14% by weight of bleached birch/pine sulphate pulp (60/40) refined
to 200° CSF and 30% by weight of china clay. To the stock was added 25 g/l of a colloidal
fraction, bleach water from a paper mill. Stock volume was 800 ml and pH about 7.
Calcium chloride was added to the stock to adjust the conductivity to 0.5 mS/cm. The
obtained stock is referred to as standard stock. Additional amounts of calcium chloride
were added to the standard stock in order to prepare a medium conductivity stock (2.0
mS/cm) and a high conductivity stock (5.0 mS/cm).
[0046] The stock was stirred in a baffled jar at a speed of 1500 rpm throughout the test
and chemicals additions were conducted as follows: i) adding cationic polymer to the
stock following by stirring for 30 seconds, ii) adding anionic polymer to the stock
followed by stirring for 15 seconds, iii) draining the stock while automatically recording
the drainage time. If used, the ATC was added to the stock followed by stirring for
30 seconds prior to i) adding cationic polymer and ii) adding anionic polymer according
to the procedure described above.
[0047] Table 1 shows the dewatering (drainage) effect at various dosages of the cationic
polymer C1, calculated as dry polymer on dry stock system, and various dosages of
the anionic polymers A1-ref, A1 and A2, calculated as dry polymer on dry stock system.
The standard stock was used in Test Nos. 1-5 and the high conductivity stock was used
in Test Nos. 6-9.
Table 1
Test No. |
C1 Dosage [kg/t] |
A Dosage [kg/t] |
Dewatering time [s] |
A1-ref |
A1 |
A2 |
1 |
30 |
0 |
19.0 |
19.0 |
19.0 |
2 |
30 |
0.5 |
17.5 |
17.0 |
15.5 |
3 |
30 |
1.0 |
14.6 |
12.6 |
12.1 |
4 |
30 |
2.0 |
12.8 |
9.0 |
8.4 |
5 |
30 |
3.0 |
9.8 |
8.7 |
7.2 |
6 |
20 |
0 |
26.4 |
26.4 |
26.4 |
7 |
20 |
2.0 |
21.5 |
15.7 |
15.6 |
8 |
20 |
3.0 |
17.6 |
14.6 |
13.7 |
9 |
20 |
4.0 |
15.7 |
14.5 |
13.4 |
Example 3
[0048] First pass retention was evaluated by means of a nephelometer by measuring the turbidity
of the filtrate from the Dynamic Drainage Analyser (DDA), the white water, obtained
by draining the stock obtained in Example 2. The results are shown in Table 2.
Table 2
Test No. |
C1 Dosage [kg/t] |
A Dosage [kg/t] |
Turbidity [NTU] |
A1-ref |
A1 |
A2 |
1 |
30 |
0.5 |
56 |
49 |
55 |
2 |
30 |
1.0 |
55 |
50 |
50 |
3 |
30 |
2.0 |
52 |
47 |
48 |
4 |
30 |
3.0 |
50 |
43 |
45 |
Example 4
[0049] Drainage performance was evaluated using the cationic and anionic polymers according
to Example 1 and the standard stock and procedure according to Example 2. The results
are shown in Table 3.
Table 3
Test No. |
C1 Dosage [kg/t] |
A Dosage [kg/t] |
Dewatering time [s] |
A1 |
A3 |
A4 |
1 |
0 |
0 |
18.0 |
18.0 |
18.0 |
2 |
20 |
0 |
12.5 |
12.5 |
12.5 |
3 |
20 |
1.0 |
10.9 |
10.0 |
10.2 |
4 |
20 |
2.0 |
10.3 |
9.0 |
8.9 |
5 |
20 |
4.0 |
10.0 |
8.7 |
8.0 |
Example 5
[0050] Drainage performance was evaluated using the cationic and anionic polymers according
to Example 1 and the medium conductivity stock and procedure according to Example
2. The results are shown in Table 4.
Table 4
Test No. |
C Dosage [kg/t] |
A1 Dosage [kg/t] |
Dewatering time [s] |
C1-ref |
C1 |
C2 |
1 |
10 |
0 |
13.8 |
14.6 |
11.5 |
2 |
10 |
0.75 |
12.6 |
10.6 |
7.4 |
3 |
10 |
1.5 |
12.8 |
9.5 |
6.6 |
4 |
10 |
3.0 |
14.1 |
10.1 |
7.2 |
Example 6
[0051] Drainage performance was evaluated using the cationic and anionic polymers according
to Example 1 and the high conductivity stock and procedure according to Example 2.
The results are shown in Table 5.
Table 5
Test No. |
C1 Dosage [kg/t] |
A Dosage [kg/t] |
Dewatering time [s] |
A2-ref |
A5 |
A6 |
1 |
20 |
0 |
31.8 |
31.8 |
31.8 |
2 |
20 |
1.0 |
31.0 |
27.5 |
28.8 |
3 |
20 |
2.0 |
28.0 |
22.0 |
24.4 |
4 |
20 |
4.0 |
23.8 |
16.5 |
19.5 |
5 |
20 |
6.0 |
23.0 |
14.0 |
18.3 |
Example 7
[0052] Drainage performance was evaluated using the cationic and anionic polymers according
to Example 1 and the high conductivity stock and procedure according to Example 2.
The results are shown in Table 6.
Table 6
Test No. |
C3 Dosage [kg/t] |
A Dosage [kg/t] |
Dewatering time [s] |
A5 |
A6 |
1 |
2 |
0 |
15.8 |
15.8 |
2 |
2 |
0.25 |
13.8 |
13.3 |
3 |
2 |
0.5 |
13.2 |
12.9 |
4 |
2 |
0.75 |
13.4 |
13.1 |
5 |
2 |
1.0 |
13.5 |
13.3 |
Examples 8
[0053] Drainage and retention performance was evaluated using the cationic and anionic polymers
according to Example 1 and the standard conductivity stock and procedures according
to Examples 2 and 3. The results are shown in Table 7.
Table 7
Test No. |
C Dosage [kg/t] |
A7 Dosage [kg/t] |
Dewatering time / Turbidity [s] / NTU |
C2-ref |
C1 |
1 |
25 |
0 |
22.0/49 |
23.4/43 |
2 |
25 |
2 |
22.1/50 |
16.3/40 |
3 |
25 |
4 |
21.2/46 |
14.3/40 |
Example 9
[0054] Drainage performance was evaluated using the cationic and anionic polymers and ATC
according to Example 1 and the medium conductivity stock and procedure according to
Example 2. The results are shown in Table 8.
Table 8
Test No. |
ATC Dosage [kg/t] |
C Dosage [kg/t] |
A7 Dosage [kg/t] |
Dewatering time [s] |
C3-ref |
C3 |
1 |
3 |
3 |
1 |
20.8 |
11.0 |
2 |
3 |
3 |
1.5 |
17.9 |
9.3 |
3 |
3 |
3 |
2 |
14.7 |
7.9 |
Example 10
[0055] Drainage and retention performance was evaluated using the cationic and anionic polymers
and ATC according to Example 1 and the medium conductivity stock and procedures according
to Examples 2 and 3. The results are shown in Table 9.
Table 9
Test No. |
ATC Dosage [kg/t] |
C Dosage [kg/t] |
A8 Dosage [kg/t] |
Dewatering time / Turbidity [s] / NTU |
C3-ref |
C3 |
1 |
3 |
3 |
2 |
21.4/49 |
11.1/40 |
2 |
3 |
3 |
3 |
17.4/46 |
9.3/40 |
3 |
3 |
3 |
4 |
15.6/48 |
8.9/45 |
Example 11
[0056] Drainage performance was evaluated using the cationic and anionic polymers according
to Example 1 and the standard conductivity stock and procedures according to Example
2. The results are shown in Table 10.
Table 10
Test No. |
C Dosage [kg/t] |
A8 Dosage [kg/t] |
Dewatering time / Turbidity [s] / NTU |
C2-ref |
C1 |
1 |
25 |
1 |
23.0/47 |
20.8/44 |
2 |
25 |
2 |
22.6/50 |
19.0/43 |
3 |
25 |
4 |
22.8/49 |
18.8/45 |
4 |
25 |
6 |
22.6/49 |
16.3/40 |
5 |
25 |
8 |
22.1/50 |
15.5/42 |
1. Process for the production of paper from an aqueous suspension containing cellulosic
fibres, and optional fillers, which comprises separately adding to the suspension
a cationic organic polymer having one or more aromatic groups, the cationic polymer
being a cationic polysaccharide; and an anionic polymer having one or more aromatic
groups, the anionic polymer being selected from step-growth polymers, polysaccharides,
and naturally occurring aromatic polymers and modifications thereof, forming and draining
the suspension on a wire, with the proviso that if the anionic polymer is a step-growth
polymer it is not an anionic melamine-suffonic acid condensation polymer.
2. Process for the production of paper from an aqueous suspension containing cellulosic
fibres, and optional fillers, which comprises separately adding to the suspension
a cationic organic polymer having one or more aromatic groups, the cationic polymer
being a cationic polysaccharide and an anionic polymer having one or more aromatic
groups, forming and draining the suspension on a wire, with the proviso that the anionic
polymer is not an anionic polystyrene sulfonate or anionic melamine-sulfonic acid
condensation polymer.
3. Process according to any one of the preceding claims, characterised in that the anionic polymer is selected from condensates of an aldehyde, anionic polyurethanes,
and naturally occurring aromatic anionic polymers and modifications thereof.
4. Process according to any one of the preceding claims, characterised in that the anionic polymer is selected from condensates of an aldehyde and naphthalene-based
compounds, anionic polyurethanes being prepared from a monomer mixture comprising
aromatic isocyanates and/or aromatic alcohols, and lignin-based polymer.
5. Process according to any one of the claims 1 to 3, characterised d in that the anionic polymer is selected from step-growth polymers being anionic
benzene-based or naphthalene-based condensation polymers.
6. Process according to claim 1 or 2, characterised in that the anionic polymer is prepared from one or more aromatic compounds selected from
phenyl, phenol, naphthalene, naphthol and derivatives and mixtures thereof.
7. Process according to claim 1 or 2, characterised In that the anionic polymer is selected from tannin extracts, sulphonated lignins, benzene
sulphonic acid, benzene sulphonate, xylen sulphonic acid, xylen sulphonate, naphthalene
sulphonic acid, naphthalene sulphonate, phenol sulphonic acid, phenol sulphonate and
mixtures thereof.
8. Process for the production of paper from an aqueous suspension containing cellulosic
fibres, and optional fillers, which comprises separately adding to the suspension
a cationic organic polymer having one or more aromatic groups, and an anionic polymer
having one or more aromatic groups the anionic polymer being selected from anionic
polyurethanes, anionic polysaccharides and naturally occurring aromatic anionic polymers
and modifications thereof, forming and draining the suspension on a wire, with the
proviso that the anionic polymer is not an anionic polystyrene sulfonate or anionic
melamine-sulfonic acid condensation polymer.
9. Process according to claim 1 or 2, characterised in that the cationic polymer is cationic starch.
10. Process according to claim 8, characterised in that the cationic polymer is a vinyl addition polymer.
11. Process according to claim 10, characterised in that the cationic polymer is an acrylamide-based polymer.
12. Process , according to any one of the preceding claims, characterised in that the cationic polymer has a weight average molecular weight above about 1,000,000.
13. Process according to any one of the preceding claims, characterised in that the cationic polymer has a benzyl group.
14. Process according to any one of the claims 1 and 2, and 8 to 13, characterised in that the anionic polymer is selected from anionic polyurethanes, and naturally occurring
aromatic anionic polymers and modifications thereof.
15. Process according to any one of the claims 1 and 2, and 8 to 14, characterised in that the anionic polymer is selected from anionic polyurethanes being prepared from a
monomer mixture comprising aromatic isocyanates and/or aromatic alcohols, and lignin-based
polymers.
16. Process according to claim 8, characterised in that the anionic polymer is anionic polyurethane.
17. Process according to claim 16, characterised in that the anionic polyurethane is prepared from a monomer mixture comprising aromatic isocyanates
and/or aromatic alcohols.
18. Process according to any one of claims. 1, 2 and 8, characterised in that the anionic polymer is a lignin-based polymer.
19. Process according to any one of claims 1 to 5, characterised in that the anionic polymer is a formaldehyde-naphthalene sulfonate condensation polymer.
20. Process according to any one of the preceding claims, characterised in that the anionic polymer has a weight average molecular weight within the range of from
500 to 1,000,000.
21. Process according to any one of the preceding claims, characterised in that the cationic polymer is added in an amount of from 0.005 to 2% by weight, based on
dry suspension.
22. Process according to any one of the preceding claims, characterised in that the anionic polymer is added in an amount of from 0.005 to 1.5% by weight, based
on dry suspension.
23. Process according to any one of the preceding claims, characterised in that it further comprises adding a low molecular weight cationic organic polymer to the
suspension.
24. Process according to any one of the preceding claims, characterised in that it further comprises adding an anionic micropariculate material selected from the
group consisting of silica-based particles and clays of the smectite type.
25. Process according to any one of the preceding claims, characterised in that the suspension has a conductivity of at least 2.0 mS/cm.
26. Process according to any one of the preceding claims, characterised in that it further comprises white water recycling and introduction of from 0 to 30 tons
of fresh water per ton of paper produced.
1. Verfahren zum Herstellen von Papier aus einer wässrigen Suspension, die cellulosehaltige
Fasern und optionale Füllstoffe enthält, welches die separate Zugabe eines kationischen
organischen Polymers mit einer oder mehreren aromatischen Gruppe(n), wobei das kationische
Polymer ein kationisches Polysaccharid ist; und eines anionischen Polymers mit einer
oder mehreren aromatischen Gruppe(n), wobei das anionische Polymer aus Stufenwachstumspolymeren,
Polysacchariden und natürlich vorkommenden aromatischen Polymeren und Modifikationen
davon ausgewählt ist, zu der Suspension, das Formgeben und das Entwässern der Suspension
auf einem Sieb umfasst, mit der Maßgabe, d a s s, falls das anionische Polymer ein
Stufenwachstumspolymer ist, es kein anionisches Melamin-Sulfonsäure-Kondensationspolymer
ist.
2. Verfahren zum Herstellen von Papier aus einer wässrigen Suspension, die cellulosehaltige
Fasern und optionale Füllstoffe enthält, welches die separate Zugabe eines kationischen
organischen Polymers mit einer oder mehreren aromatischen Gruppe(n), wobei das kationische
Polymer ein kationisches Polysaccharid ist, und eines anionischen Polymers mit einer
oder mehreren aromatischen Gruppe(n) zu der Suspension, das Formgeben und das Entwässern
der Suspension auf einem Sieb umfasst, mit der Maßgabe, dass das anionische Polymer
kein anionisches Polystyrolsulfonat oder anionisches Melamin-Sulfonsäure-Kondensationspolymer
ist.
3. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das anionische Polymer aus Kondensaten eines Aldehyds, anionischen Polyurethanen
und natürlich vorkommenden aromatischen anionischen Polymeren und Modifikationen davon
ausgewählt ist.
4. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das anionische Polymer aus Kondensaten eines Aldehyds und Naphthalin-basierten Verbindungen,
anionischen Polyurethanen, hergestellt aus einem Monomergemisch umfassend aromatische
Isocyanate und/oder aromatische Alkohole, und Ligninbasiertem Polymer ausgewählt ist.
5. Verfahren gemäß einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass das anionische Polymer aus Stufenwachstumspolymeren ausgewählt ist, bei denen es
sich um anionische Benzol-basierte oder Naphthalin-basierte Kondensationspolymere
handelt.
6. Verfahren gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, dass das anionische Polymer aus einer oder mehreren aromatischen Verbindung(en), ausgewählt
aus Phenyl, Phenol, Naphthalin, Naphthol und Derivaten sowie Gemischen davon, hergestellt
ist.
7. Verfahren gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, dass das anionische Polymer aus Tanninextrakten, sulfonierten Ligninen, Benzolsulfonsäure,
Benzolsulfonat, Xylolsulfonsäure, Xylolsulfonat, Naphthalinsulfonsäure, Naphthalinsulfonat,
Phenolsulfonsäure, Phenolsulfonat und Gemischen davon ausgewählt ist.
8. Verfahren zum Herstellen von Papier aus einer wässrigen Suspension, die e cellulosehaltige
Fasern und optionale Füllstoffe enthält, welches die separate Zugabe eines kationischen
organischen Polymers mit einer oder mehreren aromatischen Gruppe(n), und eines anionischen
Polymers mit einer oder mehreren aromatischen Gruppe(n), wobei das anionische Polymer
aus anionischen Polyurethanen, anionischen Polysacchariden und natürlich vorkommenden
aromatischen anionischen Polymeren und Modifikationen davon ausgewählt ist, zu der
Suspension, das Formgeben und das Entwässern der Suspension auf einem Sieb umfasst,
mit der Maßgabe, dass das anionische Polymer kein anionisches Polystyrolsulfonat oder
Melamin-Sulfonsäure-Kondensationspolymer ist.
9. Verfahren gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, dass das kationische Polymer kationische Stärke ist.
10. Verfahren gemäß Anspruch 8, dadurch gekennzeichnet, dass das kationische Polymer ein Vinyladditionspolymer ist.
11. Verfahren gemäß Anspruch 10, dadurch gekennzeichnet, dass das kationische Polymer ein Acrylamid-basiertes Polymer ist.
12. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das kationische Polymer ein Gewichtsmittel des Molekulargewichts von mehr als etwa
1.000.000 hat.
13. Verfahren gemäß einen der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das kationische Polymer eine Benzylgruppe besitzt.
14. Verfahren gemäß einem der Ansprüche 1, 2 und 8 bis 13, dadurch gekennzeichnet, dass das anionische Polymer aus anionischen Polyurethanen und natürlich vorkommenden aromatischen
anionischen Polymeren und Modifikationen davon ausgewählt ist.
15. Verfahren gemäß einem der Ansprüche 1, 2 und 8 bis 14, dadurch gekennzeichnet, dass das anionische Polymer aus anionischen Polyurethanen, hergestellt aus einem Monomergemisch
umfassend aromatische Isocyanate und/oder aromatische Alkohole, und Lignin-basierten
Polymeren ausgewählt ist.
16. Verfahren gemäß Anspruch 8, dadurch gekennzeichnet, dass das anionische Polymer ein anionisches Polyurethan ist.
17. Verfahren gemäß Anspruch 16, dadurch gekennzeichnet, dass das anionische Polyurethan aus einem Monomergemisch, umfassend aromatische Isocyanate
und/oder aromatische Alkohole, hergestellt ist.
18. Verfahren gemäß einem der Ansprüche 1, 2 und 8, dadurch gekennzeichnet, dass das anionische Polymer ein Lignin-basiertes Polymer ist.
19. Verfahren gemäß einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass das anionische Polymer ein Formaldehyd-Naphthalinsulfonat-Kondensationspolymer ist.
20. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das anionische Polymer ein Gewichtsmittel des Molekulargewichts im Bereich von 500
bis 1.000.000 hat.
21. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das kationische Polymer in einer Menge von 0,005 bis 2 Gewichtsprozent, bezogen auf
die trockenen Suspension, zugegeben wird.
22. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das anionische Polymer in einer Menge von 0,005 bis 1,5 Gewichtsprozent, bezogen
auf die trockenen Suspension, zugegeben wird.
23. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass es weiter die Zugabe eines kationischen organischen Polymers mit niedrigem Molekulargewicht
zu der Suspension umfasst.
24. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass es weiter die Zugabe eines Materials aus anionischen Mikropartikeln, ausgewählt aus
der Gruppe bestehend aus Silica-basierten Partikeln und Tonen des smektischen Typs,
umfasst.
25. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass die Suspension eine Leitfähigkeit von wenigstens 2,0 mS/cm aufweist.
26. Verfahren gemäß einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass es weiter das Recycling des Siebwassers und die Einspeisung von 0 bis 30 Tonnen Frischwassers
pro Tonne produzierten Papiers umfasst.
1. Procédé pour la production de papier à partir d'une suspension aqueuse contenant des
fibres cellulosiques, et des charges optionnelles, qui consiste à ajouter séparément
à la suspension un polymère organique cationique ayant un ou plusieurs groupes aromatiques,
le polymère cationique étant un polysaccharide cationique; et un polymère anionique
ayant un ou plusieurs groupes aromatiques, le polymère anionique étant choisi parmi
les polymères de polymérisation par étapes, les polysaccharides, et les polymères
aromatiques naturels, ainsi que leurs modifications, à former et drainer la suspension
sur une toile, sous réserve que, si le polymère anionique est un polymère de polymérisation
par étapes, il ne s'agisse pas d'un mélamine-acide sulfonique polymère anionique de
condensation .
2. Procédé pour la production de papier à partir d'une suspension aqueuse contenant des
fibres cellulosiques, et des charges optionnelles, qui consiste à ajouter séparément
à la suspension un polymère organique cationique ayant un ou plusieurs groupes aromatiques,
le polymère cationique étant un polysaccharide cationique, et un polymère anionique
ayant un ou plusieurs groupes aromatiques, à former et drainer la suspension sur une
toile, sous réserve que le polymère anionique ne soit pas un polystyrènesulfonate
anionique ou un mélamine-acide sulfonique polymère anionique de condensation .
3. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le polymère anionique est choisi parmi les condensats d'un aldéhyde, les polyuréthanes
anioniques, et les polymères anioniques aromatiques naturels, ainsi que leurs modifications.
4. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le polymère anionique est choisi parmi les condensats d'un aldéhyde et les composés
à base de naphtalène, les polyuréthanes anioniques étant préparés à partir d'un mélange
de monomères comprenant des isocyanates aromatiques et/ou des alcools aromatiques,
et les polymères à base de lignine.
5. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que le polymère anionique est choisi parmi les polymères de polymérisation par étapes
qui sont des polymères anioniques de condensation à base de benzène ou à base de naphtalène.
6. Procédé selon la revendication 1 ou 2, caractérisé en ce que le polymère anionique est préparé à partir d'un ou plusieurs composés aromatiques
choisis parmi le phényle, le phénol, le naphtalène, le naphtol et leurs dérivés et
mélanges.
7. Procédé selon la revendication 1 ou 2, caractérisé en ce que le polymère anionique est choisi parmi les extraits de tanin, les lignines sulfonés,
l'acide benzènesulfonique, le benzènesulfonate, l'acide xylènesulfonique, le xylènesulfonate,
l'acide naphtalènesulfonique, le naphtalènesulfonate, l'acide phénolsulfonique, le
phénolsulfonate, et leurs mélanges.
8. Procédé pour la production de papier à partir d'une suspension aqueuse contenant des
fibres cellulosiques, et des charges optionnelles, qui consiste à ajouter séparément
à la suspension un polymère organique cationique ayant un ou plusieurs groupes aromatiques,
et un polymère anionique ayant un ou plusieurs groupes aromatiques, le polymère anionique
étant choisi parmi les polyuréthanes anioniques, les polysaccharides anioniques et
les polymères anioniques aromatiques naturels, ainsi que leurs modifications, à former
et drainer la suspension sur une toile, sous réserve que le polymère anionique ne
soit pas un polystyrènesulfonate anionique ou un mélamine-acide sulfonique polymère
anionique de condensation .
9. Procédé selon la revendication 1 ou 2, caractérisé en ce que le polymère cationique est un amidon cationique.
10. Procédé selon la revendication 8, caractérisé en ce que le polymère cationique est un polymère d'addition de vinyle.
11. Procédé selon la revendication 10, caractérisé en ce que le polymère cationique est un polymère à base d'acrylamide.
12. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le polymère cationique a une masse moléculaire moyenne en masse supérieure à environ
1 000 000.
13. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le polymère cationique a un groupe benzyle.
14. Procédé selon l'une quelconque des revendications 1, 2 et 8 à 13, caractérisé en ce que le polymère anionique est choisi parmi les polyuréthanes anioniques et les polymères
anioniques aromatiques naturels, ainsi que leurs modifications.
15. Procédé selon l'une quelconque des revendications 1, 2 et 8 à 14, caractérisé en ce que le polymère anionique est choisi parmi les polyuréthanes anioniques préparés à partir
d'un mélange de monomères comprenant des isocyanates aromatiques et/ou des alcools
aromatiques, et les polymères à base de lignine.
16. Procédé selon la revendication 8, caractérisé en ce que le polymère anionique est un polyuréthane anionique.
17. Procédé selon la revendication 16, caractérisé en ce que le polyuréthane anionique est préparé à partir d'un mélange de monomères comprenant
des isocyanates aromatiques et/ou des alcools aromatiques.
18. Procédé selon l'une quelconque des revendications 1, 2 et 8, caractérisé en ce que le polymère anionique est un polymère à base de lignine.
19. Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce que le polymère anionique est un formaldéhyde-naphtalènesulfonate polymère de condensation
.
20. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le polymère anionique a une masse moléculaire moyenne en masse située dans la plage
allant de 500 à 1 000 000.
21. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le polymère cationique est ajouté en une quantité de 0,005 à 2 % en poids par rapport
à la suspension sèche.
22. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le polymère anionique est ajouté en une quantité de 0,005 à 1,5 % en poids par rapport
à la suspension sèche.
23. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comprend en outre l'addition à la suspension d'un polymère organique cationique
de faible masse moléculaire.
24. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comprend en outre l'addition d'un matériau microparticulaire anionique choisi dans
le groupe constitué par les particules à base de silice et les argiles de type smectite.
25. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que la suspension a une conductivité d'au moins 2,0 mS/cm.
26. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comprend en outre le recyclage d'eau collée et l'introduction de 0 à 30 tonnes
d'eau fraîche par tonne de papier produit.