Language selection

Search

Patent 2329027 Summary

Third-party information liability

Some of the information on this Web page has been provided by external sources. The Government of Canada is not responsible for the accuracy, reliability or currency of the information supplied by external sources. Users wishing to rely upon this information should consult directly with the source of the information. Content provided by external sources is not subject to official languages, privacy and accessibility requirements.

Claims and Abstract availability

Any discrepancies in the text and image of the Claims and Abstract are due to differing posting times. Text of the Claims and Abstract are posted:

  • At the time the application is open to public inspection;
  • At the time of issue of the patent (grant).
(12) Patent: (11) CA 2329027
(54) English Title: A PROCESS FOR THE PRODUCTION OF PAPER
(54) French Title: PROCEDE DE PRODUCTION DE PAPIER
Status: Deemed expired
Bibliographic Data
(51) International Patent Classification (IPC):
  • D21H 23/04 (2006.01)
  • D21H 17/24 (2006.01)
  • D21H 21/10 (2006.01)
  • D21H 21/18 (2006.01)
  • D21H 23/08 (2006.01)
  • D21H 11/14 (2006.01)
  • D21H 17/01 (2006.01)
  • D21H 17/28 (2006.01)
  • D21H 17/32 (2006.01)
  • D21H 17/37 (2006.01)
  • D21H 17/45 (2006.01)
  • D21H 17/68 (2006.01)
  • D21H 23/10 (2006.01)
(72) Inventors :
  • PERSSON, MICHAEL (Sweden)
  • HALLSTROM, HANS (Sweden)
  • CARLEN, JOAKIM (Sweden)
(73) Owners :
  • AKZO NOBEL N.V. (Netherlands (Kingdom of the))
(71) Applicants :
  • AKZO NOBEL N.V. (Netherlands (Kingdom of the))
(74) Agent: NORTON ROSE FULBRIGHT CANADA LLP/S.E.N.C.R.L., S.R.L.
(74) Associate agent:
(45) Issued: 2005-02-15
(86) PCT Filing Date: 1999-04-26
(87) Open to Public Inspection: 1999-11-04
Examination requested: 2000-10-18
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/SE1999/000679
(87) International Publication Number: WO1999/055964
(85) National Entry: 2000-10-18

(30) Application Priority Data:
Application No. Country/Territory Date
98850067.4 European Patent Office (EPO) 1998-04-27
60/083,253 United States of America 1998-04-27

Abstracts

English Abstract



The invention relates to a process for the production of paper from a
suspension containing cellulosic fibres, and optional fillers,
which comprises adding to the suspension a drainage and retention aid
comprising a cationic or amphoteric polysaccharide, forming and
dewatering the suspension on a wire, wherein the cationic poylsaccharide has a
hydrophobic group. The invention further relates to a process
for the production of paper from a suspension containing cellulosic fibres,
and optional fillers, which comprises adding to the suspension
a dry strength agent comprising a cationic or amphoteric polysaccharide,
forming and dewatering the suspension on a wire, wherein the
polysaccharide has a hydrophobic group.


French Abstract

L'invention concerne un procédé de production de papier à partir d'une suspension contenant des fibres cellulosiques, et d'éventuelles charges. Ce procédé consiste à ajouter à la suspension un auxiliaire de drainage et de rétention contenant un polysaccharide cationique ou amphotérique, à former et à déshydrater la suspension sur un fil. Le polysaccharide cationique a un groupe hydrophobe. L'invention concerne également un procédé de production de papier à partir d'une suspension contenant des fibres cellulosiques, et éventuellement des charges. Ce procédé consiste à ajouter à la suspension un agent de résistance sec contenant un polysaccharide cationique ou amphotérique, à former et à déshydrater la suspension sur un fil. Le polysaccharide contient un groupe hydrophobe.

Claims

Note: Claims are shown in the official language in which they were submitted.



-15-

Claims

1. A process for the production of paper from a suspension
containing cellulosic fibres, comprising adding to the suspension a drainage
and
retention aid comprising a cationic or amphoteric polysaccharide, forming and
dewatering the suspension on a wire, wherein the polysaccharide has a
hydrophobic group which comprises an aromatic group.
2. A process according to claim 1 wherein said suspension
additionally contains fillers.
3. A process for the production of paper from a suspension
containing cellulosic fibres, comprising adding to the suspension a drainage
and
retention aid comprising a cationic or amphoteric polysaccharide and a
component selected from anionic microparticulate materials, water-soluble
anionic vinyl addition polymers and combinations thereof, forming and
dewatering the suspension on a wire, wherein the polysaccharide has a
hydrophobic group comprising an aromatic group or the polysaccharide has the
general structural formula (I):

Image

wherein P is a residue of a polysaccharide; A is a group attaching N to the
polysaccharide residue; R1, and R2 are each H or alkyl having from 1 to 3
carbon
atoms; R3 is a hydrophobic hydrocarbon group containing at least 2 carbon
atoms; n is an integer from about 2 to about 300,000, or, alternatively, R1,
R2 and
R3 together with N form an aromatic group containing from 5 to 12 carbon
atoms;
and X- is an anionic counterion.
4. A process according to claim 3 wherein the suspension
additionally contains fillers.
5. A process according to claim 3 or 4, wherein the hydrophobic
group comprises an aromatic group.
6. A process according to claim 1, 2, 3, 4 or 5, wherein the
hydrophobic group is a benzyl group.



-16-

7. A process according to claim 3 or 4, wherein the hydrophobic
group comprises an alkyl group.
8. A process according to claim 7, wherein the hydrophobic group is
butyl, pentyl, hexyl, octyl or decyl.
9. A process according to any one of claims 1 to 8, wherein the
hydrophobic group contains from 4 to 14 carbon atoms.
10. A process according to any one of claims 1 to 8, wherein the
hydrophobic group contains from 6 to 12 carbon atoms.
11. A process according to any one of claims 1 to 10, wherein the
polysaccharide is selected from starches and guar gums.
12. A process according to any one of claims 1 to 11, wherein the
polysaccharide contains one or more anionic groups.
13. A process according to any one of claims 1 to 12, wherein the
polysaccharide is added in an amount of at least 0.1 by weight, based on dry
stock substance.
14. A process according to any one of claims 1 to 13, wherein the
drainage and retention aid comprises an anionic microparticulate material.
15. A process according to claim 14, wherein the anionic
microparticulate material is selected from silica-based particles or
bentonite.
16. A process according to claim 14 or 15, wherein the anionic
microparticulate material is selected from silica-based particles having a
specific
surface area above 50 m2/g.
17. A process according to any one of claims 1 to 16, wherein the
drainage and retention aid further comprises a low molecular weight cationic
organic polymer.
18. A process according to any one of claims 1 to 17, wherein the
suspension comprises recycled cellulosic fibres.
19. A process according to any one of claims 1 to 18, wherein the
suspension comprises de-inked pulp.
20. A process according to any one of claims 1 to 19, wherein the
suspension that is dewatered on the wire has a conductivity of at least 0.75
mS/cm.
21. A process according to claim 20, wherein the suspension that is
dewatered on the wire has a conductivity of at least 2.0 mS/cm.



-17-

22. A process according to any one of claims 1 to 21, wherein the
process further comprises dewatering the suspension on a wire to obtain a wet
web of paper and white water and recirculating the white water to form a
suspension containing the cellulosic fibres to be dewatered.
23. A process according to claim 22 wherein fresh water is introduced
into the recirculated white water, wherein the amount of fresh water
introduced is
less than 30 tons per ton of dry paper produced.

Description

Note: Descriptions are shown in the official language in which they were submitted.



CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/00679
1
A process for the production of paper
This invention relates to papermaking and more specifically to a process for
the
production of paper in which a cationic or arnphoteric polysaccharide
containing
hydrophobic substitution is added to a papermaking stock. The process provides
improved drainage and retention as well as improved dry strength of the paper
produced
by the process.
Background
In the papermaking art, an aqueous suspension containing cellulosic fibres,
and
optional fillers and additives, referred to as stock, is fed into a headbox
which ejects the
stock onto a forming wire. 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. Water obtained by dewatering
the stock,
referred to as white water, which usually contains fine particles, e.g. fine
fibres, fillers and
additives, is usually recirculated in the papermaking process. Drainage and
retention aids
are conventionally introduced into the stock in order to facilitate drainage
and increase
adsorption of fine particles onto the cellulosic fibres so that they are
retained with the
fibres on the wire. Cationic and amphoteric polysaccharides like cationic
starch and
cationic guar gums are widely used as drainage and retention aids. The
polysaccharides
can be used alone or in combination with other polymers and/or with anionic
micro-
particulate materials such as, for example, anionic inorganic particles like
colloidal silica.
Cationic and amphoteric polysaccharides are also widely used as dry strength
agents
which are introduced into the stock to produce paper with improved dry
strength.
Cationic polysaccharides are usually prepared by the reaction of a poly-
saccharide with a quaternising agent, e.g. 3-chloro-2-hydroxypropyl
trimethylammonium
chloride, 2,3-epoxypropyl trimethyl ammonium chloride, and 2-chloroethyl
trimethyl
ammonium chloride.
U.S. Patent Nos. 4,388,150; 4,755,259; 4,961,825; 5,127,994; 5,643,414;
5,447,604; 5,277,764; 5,607,552; 5,603,805; and 5,858,174; and European Patent
No.
500,770 disclose the use of cationic and amphoteric polysaccharides and
anionic inorganic
particles as stock additives in papermaking. These additives are among the
most efficient
drainage and retention aids now in use.
The Invention
According to the present invention it has been found that improved drainage
and
retention can be obtained in the manufacture of paper by using a drainage and
retention
aid comprising a cationic and/or amphoteric polysaccharide containing a
hydrophobic
group substituent, i.e. a hydrophobe. It has also been found that the cationic
andlor


CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/00679
2
amphoteric polysaccharide containing a hydrophobic group provides improved dry
strength of the paper. More specifically, the present invention relates to a
process for the
production of paper from a suspension containing cellulosic fibres, and
optional fillers,
which comprises adding to the suspension a drainage and retention aid
comprising a
cationic or amphoteric polysaccharide, forming and dewatering the suspension
on a wire,
wherein the polysaccharide has a hydrophobic group. The invention further
relates to a
process for the production of paper from a suspension containing cellulosic
fibres, and
optional fillers, which comprises adding to the suspension a dry strength
agent
comprising a cationic or amphoteric polysaccharide, forming and dewatering the
suspension on a wire, wherein the polysaccharide has a hydrophobic group. In a
preferred aspect of the invention, the process further comprises forming and
dewatering
the suspension on a wire to obtain a wet web containing cellulosic fibres, or
paper, and
white water, recirculating the white water and optionally introducing fresh
water to form a
suspension containing cellulosic fibres, and optional fillers, to be dewatered
to form paper,
wherein the amount of fresh water introduced is less than 30 tons per ton of
dry paper
produced. The invention thus relates to a process as further defined in the
claims.
The process of this invention results in improved drainage and/or retention
and
hereby the present process makes it possible to increase the speed of the
paper machine
and to use lower a dosage of additive to give a corresponding drainage and
retention effect,
thereby leading to an improved papermaking process and economic benefits.
Further
benefits observed with the present invention include improved dry strength of
the paper
produced using the polysaccharide having a hydrophobic group. Hereby it is
possible to
use lower a dosage of dry strength agent to give a corresponding paper dry
strength effect.
The process of this invention is suitably used for the treatment of cellulosic
suspensions in
closed mills wherein the white water is repeatedly recycled with the
introduction of only low
amounts of fresh water. The process is further suitably applied to papermaking
processes
using cellulosic suspensions having high salt contents, and thus having high
conductivity
levels, for example processes with extensive white water recycling and limited
fresh water
supply and/or processes using fresh water having high salt contents.
The polysaccharide according to this invention can be selected from any
polysaccharide known in the art including, for example, starches, guar gums,
celluloses,
chitins, chitosans, glycans, galactans, glucans, xanthan gums, pectins,
mannans, dextrins,
preferably starches and guar gums. Examples of suitable starches include
potato, corn,
wheat, tapioca, rice, waxy maize, etc. Suitably the cationic polysaccharide is
water-
dispersable or, preferably, water-soluble. In a preferred embodiment of this
invention, the
polysaccharide is capable of functioning as a drainage and retention aid
(agent). The


CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/00679
3
term "drainage and retention aid", as used herein, refers to one or more
components
(aids, agents, or additives) which, when being added to a stock, give better
drainage
and/or retention than is obtained when not adding the said one or more
components. In
another preferred embodiment of this invention, the polysaccharide is capable
of
functioning as a dry strength agent. The term "dry strength agent", as used
herein, refers
to at least one component (aid, agent or additive) which, when being added to
a stock,
give better dry strength of the paper produced than is obtained when not
adding the said
component.
The polysaccharide is a hydrophobe substituted, cationic or amphoteric
polysaccharide, i.e, a polysaccharide having one or more hydrophobic groups
and one or
more cationic groups, the cationic groups suitably being tertiary amino groups
or,
preferably, quaternary ammonium groups. The polysaccharide may also contain
one or
more anionic groups which can be, for example, phosphate, phosphonate,
sulphate,
sulphonate or carboxylic acid groups and they are preferably phosphate groups.
If present,
the anionic groups can be native or introduced by means of chemical treatment
in
conventional manner; native potato starch contains a substantial amount of
covalently
bound phosphate monoester groups. In amphoteric polysaccharides, cationic
groups are
preferably present in a predominant amount.
The hydrophobic group of the polysaccharide can be attached to a heteroatom
like oxygen present in the polysaccharide. Preferably, the hydrophobic group
is attached to
a heteroatom, e.g. nitrogen or oxygen, the heteroatom optionally being
charged, for
example when it is a nitrogen, or a group comprising such a heteroatom, e.g.,
amide, ester
or ether, which, in turn, can be attached to the polysaccharide backbone (main
chain), for
example via a chain of atoms. The hydrophobic group has at least 2, usually at
least 3,
suitably at least 4 and preferably at least 6 carbon atoms; and usually up to
about 20,
suitably up to 14 and preferably up to 92 carbon atoms. The hydrophobic group
can be
selected from aromatic (aryl) groups, aliphatic hydrocarbon groups, and
mixtures of such
groups. Examples of suitable hydrophobic aliphatic groups include linear,
branched and
cyclic alkyl groups like ethyl; propyl, e.g. n-propyl and iso-propyl; butyl,
e.g. n-butyl, iso-
butyl and t-butyl; pentyl, e.g. n-pentyl, neo-penyl and iso-pentyl; hexyl,
e.g. n-hexyl and
cyclohexyl; octyl, e.g. n-octyl; decyl, e.g. n-decyl; and dodecyl, e.g. n-
dodecyl; and
tetradecyl. Examples of suitable aromatic groups and groups comprising an
aromatic group
include aryl and aralkyl 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 where one or more
substituents


CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/00679
4
attached to said aromatic groups can be selected from hydroxyl, halides, e.g.
chloride,
nitro, and hydrocarbon groups having from 1 to 4 carbon atoms.
Particularly suitable polysaccharides according to the invention include those
comprising the general structural formula (I):
R, (I)
X-
P-{-A-N+-Rz)n
R3
wherein P is a residue of a polysaccharide; A 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 (- CHZ - CH(OH) - CH2 - ); R, and
R2 are
each H or, preferably, a hydrocarbon group, suitably alkyl, having from 1 to 3
carbon
atoms, suitably 1 or 2 carbon atoms; R3 is a hydrophobic hydrocarbon group
containing
at least 2 carbon atoms, suitably 4 to 14 and preferably 6 to 12 carbon atoms,
the
hydrophobic group suitably being as defined above, preferably a group selected
from
alkyl and aralkyl groups, e.g. benzyl and phenylethyl groups; n is an integer
from about 2
to about 300,000, suitably from 5 to 200,000 and preferably from 6 to 125,000
or,
alternatively, R,, R2 and R3 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.
The hydrophobic group modified cationic or amphoteric polysaccharide can have
a
degree of substitution varying over a wide range; the degree of cationic
substitution (DSO)
can be from 0,01 to 0,5, suitably .from 0,02 to 0,3, preferably from 0,025 to
0,2, the degree
of hydrophobic substitution (DSH) can be from from 0,01 to 0,5, suitably from
0,02 to 0,3,
preferably from 0,025 to 0,2, and the degree of anionic substitution {DSA) can
be from 0 to
0,2, suitably from 0 to 0,1, preferably from 0 to 0,05.
The polysaccharides according to the invention can be prepared by subjecting a
polysaccharide to cationic and hydrophobic modification in known manner using
one or
more agents containing a cationic group andlor a hydrophobic group, for
example by
reacting the agent with the polysaccharide in the presence of an alkaline
substance such as
an alkali metal or alkaline earth metal hydroxide. The polysaccharide to be
subjected to
cationic and hydrophobic modification can be non-ionic, anionic, amphoteric or
cationic.
Suitable modifying agents include non-ionic agents such as, for example,
hydrophobe
substituted succinic anhydrides; alkylene oxides, e.g. propylene oxide and
butylene oxide;


CA 02329027 2000-10-18
-5-
alkyl halides, e.g. decyl bromide and docecyl bromide; aralkyl halides, e.g.
benzyl chloride and benzyl bromide; the reaction products of epichlorohydrin
and
dialkylamines having at least one substituent comprising a hydrophobic group
as
defined above, including 3-dialkyl-amino-1,2-epoxypropanes; and cationic
5 agents such as, for example, the reaction product of epichlorohydrin and
tertiary
amines having at least one substituent comprising a hydro-, phobic group as
defined above, including trialkylamines, alkaryldialkylamines, e.g. dimethyl-
benzylamine; arylamines, e.g. pyridine and quinoline. Suitable cationic agents
of
this type include 2,3-epoxypropyl trialkylammonium halides and
1o halohydroxypropyl trialkylammonium halides, e.g. N-(3-chloro-2-
hydroxypropyl)-
N-(hydrophobic alkyl)-N,N-di(lower alkyl)ammonium chloride and N-glycidyl-N-
(hydrophobic alkyl)-N,N-di(lower alkyl)ammonium chloride where the
hydrophobic alkyl group is as defined above, notably octyl, decyl and dodecyl,
and the lower alkyl is methyl or ethyl; and halohydroxypropyl-N,N-dialkyl-N-
15 alkarylammonium halides and N-glycidyl-N-(alkaryl)-N,N-dialkylammonium
chloride, e.g. N-(3-chloro-2-hydroxypropyl)-N-(alkaryl)-N,N-di(lower
alkyl)ammonium chloride where the alkaryl and lower alkyl groups are as
defined
above, particularly N-(3-chloro-2-hydroxypropyl)-N-benzyl-N,N-dimethyl-
ammonium chloride; and N-(3-chloro-2-hydroxypropyl) pyridinium chloride.
2o Generally, when using a non-ionic hydrophobic agent, the polysaccharide is
suitably rendered cationic by using any of the cationic agents known in the
art
before or after the hydrophobic modification. Examples of suitable cationic
and/or hydrophobic modifying agents, hydrophobic group modified
polysaccharides and methods for their preparation include those described in
25 U.S. Patent Nos. 4,687,519 and 5,463,127; International Patent Application
WO
94/24169, European Patent Application No. 189 935; and S.P. Patel, R.G. Patel
and V.S. Patel, Starch/Starke, 41 (1989), No. 5, pp. 192-196.
In a preferred embodiment, the polysaccharide according to the invention
is used in conjunction with at least one additional stock additive, in
particular for
3o further improving drainage and/or retention, thereby forming a drainage and
retention aid comprising two or more components, usually referred to as
drainage and retention aids. The term "drainage and retention aids", as used
herein, refers to two or more components (aids, agents or additives) which,
when
being added to a stock, give better drainage and/or retention than is obtained


CA 02329027 2000-10-18
-6-
when not adding the components. Examples of suitable stock additives of this
type include anionic microparticulate materials, e.g. anionic organic
particles and
anionic inorganic particles, water-soluble anionic vinyl addition polymers,
low
molecular weight cationic organic polymers, aluminium compounds, and
combinations thereof. In a preferred aspect of this embodiment, the
polysaccharide is used in conjunction with an anionic microparticulate
material,
notably with anionic inorganic particles. In another preferred aspect of this
embodiment, the polysaccharide is used in conjunction with anionic inorganic
particles and a low molecular weight cationic organic polymer. In yet another
1o preferred aspect of this embodiment, the polysaccharide is used in
conjunction
with anionic inorganic particles and an aluminium compound. The anionic
microparticulate material according to the invention can be selected from
inorganic and organic particles.
Anionic inorganic particles that can be used according to the invention
include anionic silica-based particles and clays of the smectite type. It is
preferred that the anionic inorganic particles are in the colloidal range of
particle
size. Anionic silica-based particles, i.e. particles based on Si02 or silicic
acid, are
preferably used and such particles are usually supplied in the form of aqueous
colloidal dispersions, so-called sols. Examples of suitable silica-based
particles
2o include colloidal silica and different types of polysilicic acid. The
silicabased sols
can also be modified and contain other elements, e.g. aluminium and/or boron,
which can be present in the aqueous phase and/or in the silica-based
particles.
Suitable silica-based particles of this type include colloidal aluminium-
modified
silica and aluminium silicates. Mixtures of such suitable silica-based
particles
25 can also be used. Drainage and retention aids comprising suitable anionic
silica-
based particles are disclosed in U.S. Patent Nos. 4,388,150; 4,927,498;
4,954,220; 4,961,825; 4,980,025; 5,127,994; 5,176,891; 5,368,833; 5,447,604;
5,470,435; 5,543,014; 5,571,494; 5,573,674; 5,584,966; 5,603,805; 5,688,482;
and 5,707,493.
3o Anionic silica-based particles suitably have an average particle size
below about 50 nm, preferably below about 20 nm and more preferably in the
range of from about 1 to about 10 nm. As conventional in silica chemistry, the
particle size refers to the average size of the primary particles, which may
be
aggregated or non-aggregated. The specific surface area of the silica-based


CA 02329027 2000-10-18
-7-
particles is suitably above 50 m2/g and preferably above 100 m2/g. Generally,
the
specific surface area can be up to about 1700 m2/g and preferably up to 1000
m2/g. The specific surface area can be measured by means of titration with
NaOH in known manner, e.g. as described by Sears in Analytical Chemistry
28(1956):12, 1981-1983 and in U.S. Patent No. 5,176,891. The given area thus
represents the average specific surface area of the particles.
In a preferred embodiment of the invention, the anionic inorganic
particles are silica-based particles having a specific surface area within the
range of from 50 to 1000 m2/g; preferably from 100 to 950 m2/g. Sols of silica-

1o based particles these types also encompass modified sols like aluminium-
containing silica-based sols and boron-containing silica-based sols.
Preferably,
the silica-based particles are present in a sol having an S-value in the range
of
from 8 to 45%, preferably from 10 to 30%, containing silica-based particles
with
a specific surface area in the range of from 300 to 1000 m2/g, suitably from
500
15 to 950 m2/g, and preferably from 750 to 950 m2/g, which sots can be
modified
with aluminium and/or boron as mentioned above. For example, the particles can
be surfacemodified with aluminium to a degree of from 2 to 25% substitution of
silicon atoms. The Svalue can be measured and calculated as described by Iler
& Dalton in J. Phys. Chem. 60(1956), 955-957. The S-value indicates the degree
20 of aggregate or microgel formation and a lower S-value is indicative of a
higher
degree of aggregation.
In yet another preferred embodiment of the invention, the silica-based
particles are selected from polysilicic acid and modified polysilicic acid
having a
high specific surface area, suitably above about 1000 m2/g. The specific
surface
25 area can be within the range of from 1000 to 1700 m2/g and preferably from
1050 to 1600 m2/g. The sots of modified polysilicic acid can contain other
elements, e.g. aluminium and/or boron, which can be present in the aqueous
phase and/or in the silica-based particles. In the art, polysilicic acid is
also
referred to as polymeric silicic acid, polysilicic acid microgel, polysilicate
and
3o polysilicate microgel, which are all encompassed by the term polysilicic
acid
used herein. Aluminium-containing compounds of this type are commonly also
referred to as polyaluminosilicate and polyaluminosilicate microgel, which are
both encompassed by the terms colloidal aluminium-modified silica and
aluminium silicate used herein.


CA 02329027 2000-10-18
_ $ _
Clays of the smectite type that can be used in the process of the
invention are known in the art and include naturally occurring, synthetic and
chemically treated materials. Examples of suitable smectite clays include
montmorillonite/bentonite, hectorite, beidelite, nontronite and saponite,
5 preferably bentonite and especially such bentonite which after swelling
preferably has a surface area of from 400 to 800 m2/g. Suitable clays are
disclosed in U.S. Patent Nos. 4,753,710; 5,071,512; and 5,607,552.
Anionic organic particles that can be used according to the invention
include highly cross-linked anionic vinyl addition polymers, suitably
copolymers
1o comprising an anionic monomer like acrylic acid, methacrylic acid and
sulfonated
or phosphonated vinyl addition monomers, usually copolymerized with nonionic
monomers like (meth)acrylamide, alkyl (meth)acrylates, etc. Useful anionic
organic particles also include anionic condensation polymers, e.g. melamine-
sulfonic acid sols.
15 Low molecular weight (hereinafter LMW) cationic organic polymers that
can be used according to the invention include those commonly referred to and
used as anionic trash catchers (ATC). ATC's are known in the art as
neutralizing
and/or fixing agents for detrimental anionic substances present in the stock
and
the use thereof in combination with drainage and retention aids often provide
2o further improved drainage and/or retention. 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,
polyethyleneimines, homo- and copolymers based on diallyldimethyl ammonium
25 chloride, (meth)acrylamides and (meth)acrylates. The molecular weight of
the
LMW cationic organic polymer 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 preferably about 200, 000.
Aluminium compounds that can be used according to this invention
3o include alum, aluminates, aluminium chloride, aluminium nitrate and
polyaluminium compounds, such as polyaluminium chlorides, polyaluminium
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


CA 02329027 2000-10-18
-8a-
anions from sulfuric acid, phosphoric acid, organic acids such as citric acid
and
oxalic acid.
The components of drainage and retention aids according to the
invention can be added to the stock in conventional manner and in any order.
When using an anionic microparticulate material, it is preferred to add the
hydrophobe substituted, cationic or amphoteric polysaccharide to the stock
before adding the microparticulate material, even if the opposite order of
addition
may be used. It is further preferred to add the polysaccharide before a shear
stage, which can be selected from pumping, mixing, cleaning, etc., and to add
1o the anionic particles after that shear stage. When using an LMW cationic
organic
polymer and/or an aluminium compound, such components are preferably
introduced into the stock prior to introducing the polysaccharide and anionic
microparticulate material, if used. Alternatively, the LMW cationic organic
polymer and polysaccharide can be introduced into the stock essentially
simultaneously, either separately or in admixture, e.g. as disclosed in U.S.
Patent No. 5,858,174.
The dry strength agent and drainage and retention aids) according to the
invention are added into the stock to be dewatered in amounts which can vary
within wide limits depending on, inter alia, type and number of components,
type
of furnish, filler content, type of filler, point of addition, salt content,
etc. Generally
the components) are added in an amount that give better paper dry strength
and/or drainage and/or retention than is obtained when not adding the
component(s). The hydrophobe substituted, cationic or amphoteric
polysaccharide is usually added in an amount of at least 0,01 %, often at
least
0,1% by weight, based on dry stock substance, and the upper limit is usually
10% and


CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/00679
9
suitably 2% by weight. When using an anionic microparticulate material, it is
usually added
in an amount of at least 0.001 % by weight, often at least 0.005% by weight,
based on dry
substance of the stock, and the upper limit is usually 1.0% and suitably 0.6%
by weight.
When using anionic silica-based particles, the total amount added is suitably
within the
range of from 0.005 to 0.5% by weight, calculated as Si02 and based on dry
stock
substance, preferably within the range of from 0.01 to 0.2% by weight. When
using an
LMW cationic organic polymer in the process, it can be added in an amount of
at least
0.05%, based on dry substance of the stock to be dewatered. Suitably, the
amount is in the
range of from 0.07 to 0.5%, preferably in the range from 0.1 to 0.35%. When
using an
aluminium compound in the process, the total amount introduced into the stock
to be
dewatered is dependent on the type of aluminium compound used and on other
effects
desired from it. It is for instance well known in the art to utilise aluminium
compounds as
precipitants for rosin-based sizing agents. The total amount added is usually
at least
0.05%, calculated as AI203 and based on dry stock substance. Suitably the
amount is in the
range of from 0.5 to 3.0%, preferably in the range from 0.1 to 2.0%.
The process of the invention is preferably used in the manufacture of paper
from a
suspension containing cellulosic fibers, and optional fillers, having a high
conductivity.
Usually, the conductivity of the stock that is dewatered on the wire is at
least 0.75 mS/cm,
suitably at least 2.0 mS/cm, preferably at least 3.5 mS/cm. Very good drainage
and
retention results have been observed at conductivity levels above 5.0 mS/cm
and even
above 7.5 rnSlcm. 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), where the
various salts can
be based on mono-, di- and multivalent cations like alkali metals, e.g. Na+
and K+, alkaline
earths, e.g. Ca2+ and Mgz+, aluminium ions, e.g. AI3+, Al(OH)2' and
polyaluminium ions, and
mono-, di- and multivalent anions like halides, e.g., CI-, sulfates, e.g. S042-
and HS04-.
carbonates, e.g. C032~ and HC03 , silicates and lower organic acids. The
invention is
particularly useful in the manufacture of paper from stocks having high
contents of salts of
di- and multivalent cations, and usually the cation content is at least 200
ppm, suitably at
least 300 ppm and preferably at least 400 ppm. The salts can be derived from
the cellulosic
fibres and fillers used to form the stock, in particular in integrated mills
where a
concentrated aqueous fibre suspension from the pulp mill normally is mixed
with water to
form a dilute suspension suitable for paper manufacture in the paper mill. The
salt may also


CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/00679
be derived from various additives introduced into the stock, from the fresh
water supplied to
the process, or be added deliberately, 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.
5 The present invention further encompasses papermaking processes where white
water is extensively recirculated (recycled), 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. Recirculation of white water obtained in
the process
10 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, if used: and
before, simultaneous with or after introducing the polysaccharide. 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 suspension containing
cellulosic
fibres to dilute it so as to form the suspension to be dewatered, before or
after mixing the
stock with white water and before, between, simultaneous with or after
introducing the
components of drainage and retention aids, if used; and before, simultaneous
with or after
introducing the polysaccharide.
Further additives which are conventional in papermaking can of course be used
in
combination with the additives according to the invention, such as, for
example, additional
dry strength agents, wet strength agents, sizing agents, e.g. those based on
rosin, ketene
dimers and acid anhydrides, optical brightening agents, dyes, 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.
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
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 suspensions can be based on fibres from chemical pulp such as
sulphate,
sulphite and organosolv pulps, mechanical pulp such as therrnomechanical pulp,
chemo-


CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/00679
11
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. The invention is particularly useful in the manufacture of
paper from
suspensions based on pulps comprising recycled fibres and de-inked pulp, and
the content
of cellulosic fibres of such origin can be up to 100%, suitably from 20 to
100%.
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.
Examale 1
Cationised polysaccharides were prepared by reacting native potato starch with
a
quaternising agent according to the general procedure described in European
Patent
Application No. 189 935. The quaternising agents are commercially available
from for
example Degussa, or were prepared according to the general procedure described
in
U.S. Patent No. 5,463,127. The starches were dissolved in water and used as
0.5%
aqueous solutions.
Polysaccharides according to the invention, P1 to P3, and polysaccharides
intended for comparison purposes, Ref. 1 and Ref. 2, were prepared from the
following
starting materials:
P1: Cationised starch obtained by quarternisation of native potato starch with
3-
chloro-2-hydroxypropyl dimethyl benzyl ammonium chloride to 0.8% N.
P2: Cationised starch obtained by quarternisation of native potato starch with
3-chloro-
2-hydroxypropyl dimethyl benzyl ammonium chloride to 1.3% N.
P3: Cationised starch obtained by quarternisation of native potato starch with
3-chloro-
2-hydroxypropyl dimethyl octyl ammonium chloride to 0.9% N.
Ref. 1: Cationised starch obtained by quarternization of native potato starch
with 3-
chloro-2-hydroxypropyl trimethyl ammonium chloride to 0.8% N.
Ref. 2: Cationised starch obtained by quarternization of native potato starch
with 2,3-
epoxypropyl trimethyl ammonium chloride to 1.3% N.
Example 2
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. First
pass retention


CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/00679
12
was evaluated by means of a nephelometer by measuring the turbidity of the
filtrate, the
white water, obtained by draining the stock.
The furnish used was 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 40 g/I
of a colloidal
fraction, bleach water from an SC mill, filtrated through a 5 wm screen and
concentrated
with an OF filter, cut off 200,000. Stock volume was 800 ml and pH about 7.
Calcium
chloride was added to the stock to adjust the conductivity to 5.0 mS/cm (Test
Nos. 1-3),
and 7.5 mS/cm (Test Nos. 4-6).
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 polysaccharide to
the stock
following by stirring for 30 seconds, ii) adding anionic inorganic particles
to the stock
followed by stirring for 15 seconds, iii) draining the stock while
automatically recording
the drainage time.
The polysaccharides used in the test series were P1 and Ref. 1 according to
Example 1. The anionic inorganic particles used were silica-based particles of
the type
disclosed in U.S. Patent No. 5,368,833. The sol had an S-value of about 25%
and
contained silica particles with a specific surface area of about 900 mz/g
which were
surface-modified with aluminium to a degree of 5%.
Table 1 shows the dewatering and retention effect at various dosages of
cationized starch, calculated as dry starch on dry stock system, and silica-
based
particles, calculated as Si02 and based on dry stock system.
Table 1
Test Starch Si02 Dewatering Turbidity
time


No. Dosage Dosage [sec] [NTU]


[kglt] [kglt] P1 Ref.1 P1 Ref.1


1 7.5 3 I 17.0 20.6 51 61


2 10 3 16.0 20.0 54 54


3 15 3 15.0 21.0 48 52


4 7.5 1.5 18.1 22.3 53 64


5 10 1.5 16.6 22.1 55 60


6 15 1.5 15.5 24.0 50 58


Example 3
In this test series, dewatering performance was evaluated according to the
procedure described in Example 2.


CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/00679
13
The furnish was the same as used in Example 2. Stock volume was 800 ml and
pH about 7. Calcium chloride was added to the stock to adjust the conductivity
to 1.5
mSlcm (Test Nos. 1-3); 3.5 mS/cm (Test Nos. 4-5); and 5.0 mS/cm (Test Nos. 6-
7).
The polysaccharides used for in the test series were P2 and Ref. 2 according
to
Example 1. The anionic inorganic particles according to Example 2 were
similarly used in
this test series.
Table 2 shows the dewatering effect at various dosages of drainage and
retention aids, calculated as dry starch and Si02 on dry stock system.
Table 2
Test Starch Si02 Dewatering
No. Dosage Dosage time
[s]


[kglt] [kglt] P2 Ref.2


1 0 0 22.5 22.5


2 5 3 16.3 18.0


3 10 3 10.3 10.7


4 5 3 11.6 13.4


5 10 3 9.9 10.4


6 5 3 13.1 17.9


7 10 3 10.8 15.0


Example 4
In this test series, the dewatering effect was evaluated according to the
procedure described in Example 2 except that the drainage and retention aids
also
comprised a low molecular weight cationic polyamine; ATC. The polyamine was
added to
the stock followed by stirring far 30 seconds before addition of cationized
polysaccharide
and then anionic inorganic particles.
The furnish used was based on 70% deinked pulp, 15% by weight of peroxide
bleached TMP/SGW pulp (80120), and 15% by weight of bleached birch/pine
sulphate
pulp (60140) refined to 200° CSF. Stock volume was 800 ml and pH about
7. Calcium
chloride was added to the stock to adjust the conductivity to 1.0 mS/cm (Test
No. 1 ), 2.0
mS/cm (Test No. 2), 4.0 mS/cm (Test Nos. 3-4) and 7.5 mS/cm (Test No 5).
The polysaccharides used for in the test series were P1, P2, Ref. 1 and Ref. 2
according to Example 1. The anionic inorganic particles according to Example 2
were
similarly used.
Table 3 shows the dewatering effect at various dosages of drainage and
retention aids, calculated as dry polyamine, starch and Si02 on dry stock
system.


CA 02329027 2000-10-18
WO 99/55964 PCT/SE99/006'79
14
Table 3
Test ATC Starch Si02 Dewatering
No. DosageDosage Dosage time
[s]


[kg/t][kglt] [kglt] P1 P3 Ref.1 Ref.2


1 3 2.5 3 12.1 - 13.2 -


2 3 2.5 3 12.3 12.9 13 -


3 3 2.5 3 13.3 13.9 14.5


4 3 5 3 11.6 12.8 73 -


3 7.5 3 - 13.8 - 16


Example 5
Dry strength performance was evaluated with a Dynamic Sheet Former (Formette
5 Dynamique), supplied by Fibertech AB, Sweden, and a Tensile Strength Tester
supplied by
Lorentzen & Wettre, Sweden. Dewatering effect was evaluated according to the
procedure
described in Example 4.
The furnish according to Example 2 was used. Stock consistency was 0.3%.
Conductivity of the stock was adjusted by addition of calcium chloride.
Additives and order
of addition according to Example 4 were used in this test series. The
polyamine was added
in an amount of 3 kg/ton, calculated as dry polyamine on dry stock system. The
silica-
based particles were added in an amount of 3 kg/ton, calculated as SiOz and
based on dry
stock system.
Paper sheets were formed in the Dynamic Sheet Former by adding the chemicals
to the stock in the mixing chest, pumping the stock through a traversing
nozzle into the
rotating drum onto the water film on top of the wire, draining the stock to
form a sheet,
pressing and drying the sheet. The sheets were cut into strips that were
evaluated in the
Tensile Strength Tester. The square mean value of the tensile strength index
of the
machine and cross direction of the paper sheets was calculated and compared.
Table 4 shows the dewatering time and tensile strength of the sheets obtained
at various starch dosages, calculated as dry starch on dry stock system.
Table 4
Test ConductivityStarch Dewatering Tensile
No. Dosage time Strength
[sec] [kNmlkg]


[mSlcm] [kglt] P2 Ref.2 P2 Ref.2


1 2.5 5.0 7.9 8.4 36.0 35.2


2 5.0 5.0 8.6 11.3 36.1 35.8


3 10.0 5.0 11.1 13.0 35.3 35.0


4 10.0 10.0 13.3 15.1 36.5 34.0



Representative Drawing

Sorry, the representative drawing for patent document number 2329027 was not found.

Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 2005-02-15
(86) PCT Filing Date 1999-04-26
(87) PCT Publication Date 1999-11-04
(85) National Entry 2000-10-18
Examination Requested 2000-10-18
(45) Issued 2005-02-15
Deemed Expired 2010-04-26

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Request for Examination $400.00 2000-10-18
Registration of a document - section 124 $100.00 2000-10-18
Application Fee $300.00 2000-10-18
Maintenance Fee - Application - New Act 2 2001-04-26 $100.00 2000-10-18
Maintenance Fee - Application - New Act 3 2002-04-26 $100.00 2002-04-02
Maintenance Fee - Application - New Act 4 2003-04-28 $100.00 2003-03-24
Maintenance Fee - Application - New Act 5 2004-04-26 $200.00 2004-03-23
Final Fee $300.00 2004-11-29
Maintenance Fee - Patent - New Act 6 2005-04-26 $200.00 2005-04-01
Maintenance Fee - Patent - New Act 7 2006-04-26 $200.00 2006-03-30
Maintenance Fee - Patent - New Act 8 2007-04-26 $200.00 2007-03-30
Maintenance Fee - Patent - New Act 9 2008-04-28 $200.00 2008-03-31
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
AKZO NOBEL N.V.
Past Owners on Record
CARLEN, JOAKIM
HALLSTROM, HANS
PERSSON, MICHAEL
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

To view selected files, please enter reCAPTCHA code :



To view images, click a link in the Document Description column. To download the documents, select one or more checkboxes in the first column and then click the "Download Selected in PDF format (Zip Archive)" or the "Download Selected as Single PDF" button.

List of published and non-published patent-specific documents on the CPD .

If you have any difficulty accessing content, you can call the Client Service Centre at 1-866-997-1936 or send them an e-mail at CIPO Client Service Centre.


Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Description 2000-10-19 15 893
Claims 2000-10-19 3 95
Cover Page 2001-02-14 1 43
Abstract 2000-10-18 1 56
Description 2000-10-18 14 910
Claims 2000-10-18 3 161
Cover Page 2005-01-21 1 34
Assignment 2000-10-18 4 173
PCT 2000-10-18 14 497
Prosecution-Amendment 2000-10-18 10 412
Prosecution-Amendment 2003-05-26 2 69
Prosecution-Amendment 2003-11-06 5 201
Correspondence 2004-11-29 1 27