U.S. patent application number 09/740546 was filed with the patent office on 2002-08-22 for structurally rigid polymer coagulants as retention and drainage aids in papermaking.
Invention is credited to Dunham, Andrew J., Ward, William J..
Application Number | 20020112836 09/740546 |
Document ID | / |
Family ID | 24976978 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020112836 |
Kind Code |
A1 |
Ward, William J. ; et
al. |
August 22, 2002 |
Structurally rigid polymer coagulants as retention and drainage
aids in papermaking
Abstract
This invention concerns a method of increasing retention and
drainage in a papermaking furnish comprising adding to the furnish
an effective amount of a structurally rigid polymeric coagulant and
an effective flocculating amount of a flocculant and a
microparticle.
Inventors: |
Ward, William J.; (Glen
Ellyn, IL) ; Dunham, Andrew J.; (DeKalb, IL) |
Correspondence
Address: |
Nalco Chemical Company
Patent & Licensing Department
One Nalco Center
Naperville
IL
60563-1198
US
|
Family ID: |
24976978 |
Appl. No.: |
09/740546 |
Filed: |
December 20, 2000 |
Current U.S.
Class: |
162/166 ;
162/167; 162/168.3; 162/181.1 |
Current CPC
Class: |
C08G 73/00 20130101;
C08G 73/02 20130101; D21H 17/54 20130101; D21H 21/10 20130101 |
Class at
Publication: |
162/166 ;
162/167; 162/168.3; 162/181.1 |
International
Class: |
D21H 017/07; D21H
017/17; D21H 017/55; D21H 017/63 |
Claims
What is claimed is:
1. A method of increasing retention and drainage in a papermaking
furnish comprising adding to the furnish an effective amount of a
structurally rigid polymeric coagulant and an effective
flocculating amount of a flocculant and a microparticle.
2. The method of claim 1 wherein the structurally polymeric
coagulant is selected from the group consisting of condensation
polymers of one or more cyclic ditertiary amines with one or more
cyclic or acyclic dihalides and condensation polymers of one or
more acyclic ditertiary amine s with one or more cyclic
dihalides.
3. The method of claim 2 wherein the structurally-rigid coagulant
has a molecular weight of from about 1000 to about 100,000.
4. The method of claim 3 wherein the cyclic ditertiary amine is
1,4-diazabicyclo [2.2.2]octane.
5. The method of claim 4 wherein the acyclic dihalide is
1,4-dihalobutyne or .alpha.,.alpha.'-dihalo-p-xylene.
6. The method of claim 1 wherein the structurally rigid polymeric
coagulant is poly(1,4-diazabicyclo [2.2.2]
octane/1,4-dichloro-2-butyne); or poly(1,4-diazabicyclo [2.2.2]
octane/.alpha.,.alpha.'-dichloro-p-xylen- e).
7. The method of claim 1 wherein the flocculent is poly(acrylic
acid/acrylamide).
8. The method of claim 1 wherein the microparticle is colloidal
borosilicate.
9. The method of claim 1 wherein the papermaking furnish is
selected from fine paper, board, and newsprint papermaking
furnishes.
10. A polymer composition comprising a condensation polymer of
1,4-diazabicyclo [2.2.2]octane and an alkynyl dihalide or an
.alpha.,.alpha.'-dihalo-p-xylene.
11. A polymer composition comprising poly(1,4-diazabicyclo [2.2.2]
octane/1,4-dichloro-2-butyne); or poly(1,4-diazabicyclo [2.2.2]
octane/.alpha.,.alpha.'-dichloro-p-xylene).
Description
TECHNICAL FIELD
[0001] This invention is directed to a method for increasing
retention and drainage in a papermaking furnish using structurally
rigid polymeric coagulants in combination with a flocculent and a
microparticle.
BACKGROUND OF THE INVENTION
[0002] In the manufacture of paper, a papermaking furnish is formed
into a paper sheet. The papermaking furnish is an aqueous slurry of
cellulosic fiber having a fiber content of about 4 weight percent
(percent dry weight of solids in the furnish) or less, and
generally around 1.5% or less., and often below 1.0% ahead of the
paper machine, while the finished sheet typically has less than 6
weight percent water. Hence the dewatering and retention aspects of
papermaking are extremely important to the efficiency and cost of
the manufacture.
[0003] Gravity dewatering is the preferred method of drainage
because of its relatively low cost. After gravity drainage more
expensive methods are used for dewatering, for instance vacuum,
pressing, felt blanket blotting and pressing, evaporation and the
like. In actual practice a combination of such methods is employed
to dewater, or dry, the sheet to the desired water content. Since
gravity drainage is both the first dewatering method employed and
the least expensive, an improvement in the efficiency of this
drainage process will decrease the amount of water required to be
removed by other methods and hence improve the overall efficiency
of dewatering and reduce the cost thereof.
[0004] Another aspect of papermaking that is extremely important to
the efficiency and cost is retention of furnish components on and
within the fiber mat. The papermaking furnish represents a system
containing significant amounts of small particles stabilized by
colloidal forces. The papermaking furnish generally contains, in
addition to cellulosic fibers, particles ranging in size from about
5 to about 1000 nm consisting of, for example, cellulosic fines,
mineral fillers (employed to increase opacity, brightness and other
paper characteristics) and other small particles that generally,
without the inclusion of one or more retention aids, would in
significant portion pass through the spaces (pores) between the mat
formed by the cellulosic fibers on the papermachine.
[0005] Greater retention of fines, fillers, and other components of
the furnish permits, for a given grade of paper, a reduction in the
cellulosic fiber content of such paper. As pulps of lower quality
are employed to reduce papermaking costs, the retention aspect of
papermaking becomes more important because the fines content of
such lower quality pulps is generally greater. Greater retention
also decreases the amount of such substances lost to the whitewater
and hence reduces the amount of material costs, the cost of waste
disposal and the adverse environmental effects therefrom. It is
generally desirable to reduce the amount of material employed in a
papermaking process for a given purpose, without diminishing the
result sought. Such add-on reductions may realize both a material
cost savings and handling and processing benefits.
[0006] An important method of enhancing dewatering while improving
the retention of cellulosic fines, mineral fillers and other
furnish components on the fiber mat employs an inorganic
microparticle in combination with a coagulant and a polymeric
flocculent. In such a system a coagulant is first added, followed
by the flocculant and the microparticle.
[0007] The coagulant is generally a low molecular weight synthetic
cationic polymer or cationic starch. The coagulant may also be an
inorganic coagulant such as alum or polyaluminum chlorides. The
coagulant addition can take place at one or several points within
the furnish make up system, including but not limited to the thick
stock, white water system, or thin stock of a machine. The
coagulant generally reduces the negative surface charges present on
the particles in the furnish, such as cellulosic fines and mineral
fillers, and thereby accomplishes a degree of agglomeration of such
particles. Further, in the presence of other detrimental anionic
species, the coagulant serves to neutralize the interfering species
enabling aggregation with the subsequent addition of a
flocculant.
[0008] The flocculent generally is a high molecular weight
synthetic polymer which bridges the particles and/or agglomerates,
from one surface to another, binding the particles into larger
agglomerates. The presence of such large agglomerates in the
furnish, as the fiber mat of the paper sheet is being formed,
increases retention. The agglomerates are filtered out of the water
onto the fiber web, whereas unagglomerated particles would, to a
great extent, pass through such a paper web. In such a program the
order of addition of the microparticle and flocculant can be
reversed successfully.
[0009] However, there is continuing need to develop improved agents
for improving the retention and drainage performance of the
papermaking furnish, thereby increasing the efficiency of pulp or
paper manufacture.
SUMMARY OF THE INVENTION
[0010] Structurally rigid polymers have been used as substitutes
for pulp in papermaking (U.S. Pat. No. 4,749,753; Japanese Patent
Application 1987-29251), but not as process additives. We have
discovered that adding structurally rigid polymeric coagulants to
papermaking furnishes results in a substantial improvement of the
retention and drainage properties of the furnishes.
[0011] Accordingly, in its principal embodiment, this invention is
directed to a method of increasing retention and drainage in a
papermaking furnish comprising adding to the furnish an effective
amount of a structurally rigid polymeric coagulant and an effective
flocculating amount of a flocculent and a microparticle.
DETAILED DESCRIPTION OF THE INVENTION
[0012] Definitions of Terms
[0013] "Structurally rigid polymers" means polymers having a
structure where the rotational conformation (degrees of freedom) of
the polymer are restricted compared with common flexible polymeric
materials. Structural rigidity is imparted to the polymeric
coagulants described herein by incorporating rigid components such
as alkenyl, alkynyl, cyloalkyl, heterocyclyl, aryl and heteroaryl
groups along the main chain of the polymer. The structurally rigid
polymers may be composed entirely of rigid components, or the rigid
components may be connected by flexible chains such as alkyl or
ether groups, so long as introduction of the flexible groups does
not substantially effect the overall rigidity of the polymer.
Further, the structurally rigid polymers should be water-soluble or
water-dispersable and have cationic charge.
[0014] "Cyclic ditertiary amine" means an aromatic or aliphatic
monocyclic or multicyclic ring system of formula 1
[0015] where "A" and "B" denote, respectively, a monocyclic,
bicyclic or fused aromatic or aliphatic ring system of from about 5
to about 10 ring atoms and R.sub.9 and R.sub.10 are alkyl of from
one to about 4 carbon atoms. The nitrogen atoms are separated by at
least one ring atom, preferably by at least two ring atoms. Where
the cyclic ditertiary amine is aliphatic, the nitrogen atoms are
further substituted with alkyl. Preferably, the alkyl groups are
connected to form a bridged heterocylic ring. The cyclic ditertiary
amine is optionally substituted with one or more substituents
selected from alkyl, alkoxy and haloalkyl. Preferred cyclic
ditertiary amines are 1,4-diazabicyclo[2.2.2]octane,
4,4-dipyridine, pyrazine and 1,4-dimethylpiperazine. A more
preferred cyclic ditertiary amine is
1,4-diazabicyclo[2.2.2]octane.
[0016] "Acyclic ditertiary amine" means an amine of formula 2
[0017] where R.sub.1-R.sub.4 are alkyl and L.sub.1 is
C.sub.1-C.sub.6 alkylene, C.sub.2-C.sub.6 alkenylene,
C.sub.2-C.sub.6 alkynylene, arylene, heteroarylene heterocycylene
or cycloalkylene. Preferred acyclic ditertiary amines are
N,N,N',N'-tetramethyl-2-butene-1,4-diamine,
N,N,N',N'-tetramethyldiaminomethane,
N,N,N',N'-tetramethyl-2,2-diaminopro- pane and
N,N,N',N'-tetramethyl-1,4-diaminocyclohexane.
N,N,N',N'-Tetramethyl-1,4-diaminocyclohexane is more preferred.
[0018] "Cyclic dihalide" means an aliphatic cylcoalkyl of formula
3
[0019] where "C" denotes a cycloalkyl of from about 5 to about 10
carbon atoms and X is halogen. The halogen-substituted carbon atoms
are separated by at least one carbon atom, preferably by at least
two carbon atoms. The cyclic dihalide is optionally substituted
with one or more substituents selected from alkyl, alkoxy and
haloalkyl. A preferred cyclic dihalides is
1,4-dichlorocyclohexane.
[0020] "Acyclic dihalide" means dihalide of formula 4
[0021] where X is halogen, L.sub.2 is C.sub.2-C.sub.6 alkylene,
C.sub.2-C.sub.6 alkenylene, C.sub.2-C.sub.6 alkynylene, arylene,
heteroarylene heterocycylene or cycloalkylene and R.sub.5-R.sub.8
are independently selected from hydrogen and alkyl. Preferred
acyclic dihalides are 1,4-dichloro-2-butyne,
trans-1,4-dichloro-2-butene, .alpha.,.alpha.'-dichloro-p-xylene and
1,3-dichloro-2,2-dimethylpropane. A more preferred acyclic dihalide
is 1,4-dichloro-2-butyne.
[0022] "Alkyl" means a monovalent group derived from a straight or
branched chain saturated hydrocarbon by the removal of a single
hydrogen atom. Representative alkyl groups include methyl, ethyl,
n- and iso-propyl, and the like.
[0023] "Alkylene" means a divalent group derived from a straight or
branched chain saturated hydrocarbon by the removal of two hydrogen
atoms. Representative alkylene groups include methylene, ethylene,
propylene, and the like.
[0024] "Alkenylene" means a divalent group derived from a straight
or branched chain hydrocarbon containing at least one carbon-carbon
double bond. Representative alkenylene include --CH.dbd.CH--,
--CH.sub.2CH.dbd.CH--, --C(CH.sub.3).dbd.CH--,
--CH.sub.2CH.dbd.CHCH.sub.- 2--, and the like.
[0025] "Alkynylene" means a divalent group derived by the removal
of two hydrogen atoms from a straight or branched chain acyclic
hydrocarbon group containing a carbon-carbon triple bond.
Representative alkynylene include --CH.ident.CH--,
--CH.ident.CH--CH.sub.2--, --CH.ident.CH--CH(CH.sub.3)--, and the
like.
[0026] "Alkoxy" and "alkoxyl" mean an alkyl--O--group wherein alkyl
is defined herein. Representative alkoxy groups include methoxyl,
ethoxyl, propoxyl, butoxyl, and the like.
[0027] "Aryl" means an aromatic monocyclic or multicyclic ring
system of about 6 to about 20 carbon atoms, preferably of about 6
to about 10 carbon atoms. The aryl is optionally substituted with
one or more alkyl, alkoxy or haloalkyl groups. Representative aryl
groups include phenyl or naphthyl, or substituted phenyl or
substituted naphthyl.
[0028] "Arylene" means a divalent group derived from an aryl as
defined herein by the removal of two hydrogen atoms, provided that
in no cases are the hydrogen atoms on adjacent carbon atoms.
[0029] "Cycloalkyl" means a non-aromatic mono- or multicyclic ring
system of about 5 to about 10 carbon atoms. Preferred ring sizes of
rings of the ring system include about 5 to about 6 ring atoms. The
cycloalkyl is optionally substituted with one one or more
substituents selected from alkyl, alkoxy and haloalkyl.
Representative monocyclic cycloalkyl include cyclopentyl,
cyclohexyl, cycloheptyl, and the like. Representative multicyclic
cycloalkyl include 1-decalin, norbornyl, adamant-(1- or 2-)yl, and
the like.
[0030] "Cycloalkylene" means a divalent group derived from a
cycloalkyl as defined herein by the removal of two hydrogen atoms,
provided that in no cases are the hydrogen atoms on adjacent carbon
atoms.
[0031] "Heteroaryl" means an aromatic monocyclic or multicyclic
ring system of about 5 to about 10, preferably from about 5 to
about 6 ring atoms, in which one or more of the atoms in the ring
system is/are element(s) other than carbon, for example nitrogen,
oxygen or sulfur. The heteroaryl is optionally substituted with one
one or more substituents selected from alkyl, alkoxy and haloalkyl.
Representative heteroaryl groups include pyridyl, quinolyl, furyl,
benzofuryl, thienyl, thiazolyl, pyrimidyl, indolyl, and the
like.
[0032] "Heteroarylene" means a divalent group derived from a
heteroaryl as defined herein by the removal of two hydrogen atoms,
provided that in no cases are the hydrogen atoms on adjacent ring
atoms.
[0033] "Heterocyclyl" means a non-aromatic saturated monocyclic or
multicyclic ring system of from about 5 to about 10 ring atoms, in
which one or more of the atoms in the ring system is/are element(s)
other than carbon, for example nitrogen, oxygen or sulfur.
Preferred ring sizes of rings of the ring system include about 5 to
about 6 ring atoms. The heterocyclyl is optionally substituted by
one or more alkyl, alkoxy or haloalkyl groups. Representative
heterocyclyl rings include piperidyl, pyrrolidinyl, piperazinyl,
morpholinyl, thiomorpholinyl, thiazolidinyl 1,3-dioxolanyl
1,4-dioxanyl, tetrahydrofuranyl, tetrahydrothiophenyl,
tetrahydrothiopyranyl, and the like.
[0034] "Heterocyclylene" means a divalent group derived from a
heterocyclyl as defined herein by the removal of two hydrogen
atoms, provided that in no cases are the hydrogen atoms on adjacent
ring atoms.
[0035] "Halogen" and "halo" mean fluorine, chlorine, bromine or
iodine.
[0036] "Haloalkyl" means an alkyl group, as defined herein, having
one, two, or three halogen atoms attached thereto. Representative
haloalkyl groups include chloromethyl, bromoethyl, trifluoromethyl,
and the like.
[0037] "Flocculant" means a chemical agent that is added to a
papermaking furnish to assist in the agglomeration of small
particles and thereby increase the retention and drainage
properties of the furnish. The flocculant may be a non-ionic,
anionic or cationic polymer having a molecular weight of at least
about 500,000, preferably of at least about 1,000,000 and more
preferably of at least about 5,000,000. The flocculant may be used
in the solid form, as an aqueous solution, as water-in-oil
emulsion, or as dispersion in water.
[0038] "Nonionic flocculent" means homopolymers, copolymers or
terpolymers and so on of nonionic monomers. Representative nonionic
monomers include acrylamide, methacrylamide, N-tertiary butyl
acrylamide, N-vinylformamide, N-vinylpyrrolidone,
N-vinylpiperidone, N-vinylcaprolactam, N-vinyl-3-methylpyrrolidone,
N-vinypyrrolidone, N-vinylpiperidone, N-vinylcaprolactam,
N-vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone,
N-vinyl-5-phenylpyrrolidone, N-vinyl-2-oxazolidone,
N-vinylimidazole, vinylacetate, maleimide, N-vinylmorpholinone,
polyethylene oxide (PEO), and the like. Preferred nonionic monomers
are acrylamide, methacrylamide and N-vinylformide. Preferred
nonionic flocculants are poly(acrylamide), poly(methacrylamide) and
poly(N-vinylformamide).
[0039] The dosage of nonionic flocculant is preferably from about
0.001 to about 0.5% (as actives) by weight based on total solids in
the slurry, more preferably from about 0.003 to about 0.2% and most
preferably from about 0.007 to about 0.1%.
[0040] "Cationic flocculent" means any water-soluble polymer of
(meth)acrylamide or any water-soluble polymer of N-vinylformamide
or related monomers which carries or is capable of carrying a
cationic charge when dissolved in water. Representative cationic
copolymers of (meth)acrylamide include copolymers of
(meth)acrylamide with dimethylaminoethyl methacrylate (DMAEM),
dimethylaminoethyl acrylate (DMAEA), diethylaminoethyl acrylate
(DEAEA), diethylaminoethyl methacrylate (DEAEM) or their quaternary
ammonium forms made with dimethyl sulfate or methyl chloride,
Mannich reaction modified polyacrylamides, diallylcyclohexylamine
hydrochloride (DACHA.backslash.HCl), diallyldimethylammonium
chloride (DADMAC), methacrylamidopropyltrimethylammonium chloride
(MAPTAC) and allyl amine (ALA).
[0041] "Anionic flocculent" any polymer comprised of anionic and
nonionic monomers means which carries or is capable of carrying a
cationic charge when dissolved in water. Representative anionic
monomers include acrylic acid, methacrylic acid,
2-acrylamido-2-methyl-1-propanesulfonic acid,
acrylamidomethylbutanoic acid, maleic acid, fumaric acid, itaconic
acid, vinyl sulfonic acid, styrene sulfonic acid, vinyl phosphonic
acid, allyl sulfonic acid, allyl phosphonic acid, sulfomethylated
acrylamide, phosphonomethylated acrylamide and the water-soluble
alkali metal, alkaline earth metal, and ammonium salts thereof. The
choice of anionic monomer is based upon several factors including
the ability of the monomer to polymerize with the desired
comonomer, the use of the produced polymer, and cost. A preferred
anionic monomer is acrylic acid. Preferred anionic flocculants are
copolymers of acrylamide and acrylic acid.
[0042] The dosage of anionic flocculant is from about 0.001 to
about 1%, preferably from about 0.01 to about 0.5% and more
preferably from about 0.02 to about 0.25% by weight based on total
solids in the slurry.
[0043] "Zwitterionic flocculent" means a polymer composed from
zwitterionic monomers and, possibly, other non-ionic monomer(s).
Representative zwitterionic polymers include homopolymers such as
the homopolymer of N,
N-dimethyl-N-(2-acryloyloxyethyl)-N-(3-sulfopropyl) ammonium
betaine, copolymers such as the copolymer of acrylamide and N,
N-dimethyl-N-(2-acryloyloxyethyl)-N-(3-sulfopropyl) ammonium
betaine, and terpolymers such as the terpolymer of acrylamide,
N-vinyl-2-pyrrolidone, and 1-(3-sulfopropyl)-2-vinylpyridinium
betaine. The use of zwitterionic flocculants in papermaking is
described in U.S. patent application Ser. No. 09/349,054,
incorporated herein by reference.
[0044] "Microparticle" means highly charged materials that improve
flocculation when used together with natural and synthetic
macromolecules. They constitute a class of retention and drainage
chemicals defined primarily by their submicron size. A three
dimensional structure, an ionic surface, and a submicron size are
the general requirements for effective microparticles.
[0045] Microparticle programs enhance the performance of current
retention programs and optimize wet end chemistry, paper quality
and paper machine efficiency. Microparticles are not designed to be
used as a sole treatment. Rather, they are used in combination with
other wet end additives to, improve retention and drainage on the
paper machine. Commonly used microparticles include:
[0046] i) copolymers of acrylic acid and acrylamide;
[0047] ii) bentonite and other clays;
[0048] iii) dispersed silica based materials;
[0049] iv) colloidal borosilicate; and
[0050] V) naphthalene sulfonate/formaldehyde condensate
polymers.
[0051] Representative copolymers of acrylic acid and acrylamide are
described in U.S. Pat. No. 5,098,520, incorporated herein by
reference.
[0052] Bentonites useful as the microparticle for this process
include: any of the materials commercially referred to as
bentonites or as bentonite-type clays, i.e., anionic swelling clays
such as sepialite, attapulgite and montmorillonite. In addition,
bentonites described in U.S. Pat. No. 4,305,781 are suitable. A
preferred bentonite is a hydrated suspension of powdered bentonite
in water.
[0053] Representative dispersed silicas have an average particle
size of from about 1 to about 100 nanometers (nm), preferably from
about 2 to about 25 nm, and more preferably from about 2 to about
15 nm. This dispersed silica, may be in the form of colloidal,
silicic acid, silica sols, fumed silica, agglomerated silicic acid,
silica gels and precipitated silicas, so long as the particle size
or ultimate particle size is within the above ranges. Dispersed
silica in water with a typical particle size of about 4 nm is
available from Nalco Chemical Company, Naperville, Ill.
[0054] Representative borosilicates are described in Patent
Cooperation Treaty Patent Application No. PCT/US98/19339,
incorporated herein by reference. Colloidal borosilicate is
available from Nalco Chemical Company, Naperville, Ill.
[0055] Naphthalene sulfonate/formaldehyde condensate polymers
useful as microparticles are available from Nalco Chemical Company,
Naperville, Ill.
[0056] Other suitable microparticles include the structurally-rigid
polymers disclosed in U.S. patent application Ser. No. XX/XXX,XXX,
filed concurrently herewith, titled "Structurally Rigid Nonionic
and Anionic Polymers as Retention and Drainage Aids in
Papermaking", incorporated herein by reference.
[0057] The amount of microparticle added is from about 0.05 to
about 5.0, preferably from about 1.5 to about 4.5 and more
preferably about 2 to about 4.5 pounds microparticle/ton. "Pounds
microparticle/ton" means pounds of actual microparticle per 2000
pounds of solids present in slurry. The abbreviation for pounds of
actual microparticle per 2000 pounds of solids present in slurry is
"lbs microparticle/ton".
[0058] The microparticle is added to the papermaking furnish either
before or after the flocculent is added to the furnish. The choice
of whether to add the microparticle before or after the flocculant
can be made by a person of ordinary skill in the art based on the
requirements and specifications of the papermaking furnish.
[0059] Preferred Embodiments
[0060] The structurally rigid polymeric coagulants of this
invention are prepared by condensation polymerization of one or
more cyclic ditertiary amine s with one or more cyclic or acyclic
dihalides condensation polymerization of one or more acyclic
ditertiary amines with one or more cyclic dihalides in a polar
solvent such as DMF, acetonitrile, DMSO or water, or mixtures
thereof. A preferred solvent is a 70:30 mixture of DMF or
acetonitrile and water. Reaction temperatures can range from about
ambient temperature to about 100.degree. C., preferably from about
40.degree. C. to about 60.degree. C. Reaction times can range from
a few hours to several days, preferably from about 10 to about 24
hours.
[0061] The structurally-rigid coagulants have a molecular weight of
from about 1000 to about 100,000, preferably from about 5000 to
about 10,000.
[0062] In a preferred aspect of this invention, the cyclic
ditertiary amine is 1,4-diazabicyclo [2.2.2]octane.
[0063] In another preferred aspect, the acyclic dihalide is
1,4-dihalobutyne or .alpha.,.alpha.'-dihalo-p-xylene.
[0064] In a more preferred aspect, the structurally rigid polymeric
coagulant is poly(1,4-diazabicyclo [2.2.2]
octane/1,4-dichloro-2-butyne) or poly(1,4-diazabicyclo [2.2.2]
octane/.alpha.,.alpha.'-dichloro-p-xylen- e).
[0065] In another preferred aspect, the flocculent is poly(acrylic
acid/acrylamide).
[0066] In another preferred aspect, the microparticle is colloidal
borosilicate.
[0067] In another preferred aspect, the papermaking furnish is
selected from fine paper, board. and newsprint papermaking
furnishes.
[0068] In another preferred aspect, this invention is directed to a
polymer composition comprising a condensation polymer of
1,4-diazabicyclo [2.2.2]octane and an alkynyl dihalide or an
.alpha.,.alpha.'-dihalo-p-xyl- ene.
[0069] In another preferred aspect, this invention is directed to a
polymer composition comprising poly(1,4-diazabicyclo [2.2.2]
octane/1,4-dichloro-2-butyne); or poly(1,4-diazabicyclo [2.2.2]
octane/.alpha.,.alpha.'-dichloro-p-xylene).
[0070] In addition to the structurally rigid coagulant, the
flocculant and the microparticle, additional additives such as
talc, cationic starch, cationic coagulant, or mixtures thereof may
be added anywhere in the system.
[0071] The appropriate dosage of structurally rigid coagulant is
determined by adding different doses of the structurally rigid
coagulant to a papermaking slurry either before, concurrently with,
or after the addition of either a flocculant alone or a flocculant
followed by a microparticle. The performance of the combined
chemical additions is monitored with the focused beam reflectance
microscope (FBRM) or other appropriate evaluative measurement
(Britt jar, dynamic drainage analyzer, etc.). The range of doses is
preferably from about 1 to about 20, more preferably from about 1
to about 8 pounds of structurally rigid coagulant/ton product.
[0072] Generally the structurally rigid coagulant is added before
the flocculant and microparticle, though exceptions are practiced
in the industry. When the coagulant is added before the flocculent,
it is added either to the white water, the thick stock, or the thin
stock. The preferred addition point is the thick stock pulp before
dilution with white water.
[0073] Alternatively, the structurally rigid coagulant is added at
several points in the papermaking process, including concurrently
with the flocculent or microparticle.
[0074] This application results in increased cleanliness of the
papermaking operation which otherwise experiences hydrophobic
deposition effecting both productivity and the quality of
paper.
[0075] The foregoing may be better understood by reference to the
following Examples, which are presented for purposes of
illustration and are not intended to limit the scope of this
invention.
EXAMPLE 1
[0076] Synthesis of rigid copolymers formed from condensation of a
cyclic diteriary amine arid an acyclic dihalide is illustrated by
the following preparation of
poly(1,4-diazabicyclo[2.2.2]octane/1,4-dichloro butyne). 5
[0077] Into a reaction flask equipped with a magnetic stirring bar,
reflux condenser, and nitrogen inlet is placed 50 ml of dry
acetonitrile and 2.00 g of 1,4-diazabicyclo[2.2.2]octane
(Dabco.TM., available from Aldrich Chemical Co., Milwaukee, Wis.).
The mixture is stirred and purged with nitrogen until a homogeneous
solution is obtained. To this is injected, at once, 2.18 g (one
equivalent) of 1,4-dichloro-2-butyne. A slight exotherm is
observed, and a solid suspension formed almost immediately. To the
reaction mixture is then added 5.0 ml of dionized water, and the
mixture is heated to 60.degree. C. for one hour. After this time,
an additional 30 ml of water is added in order to create a
homogeneous solution. The mixture is held at 60.degree. C. for an
additional 7 hours. At the end of this time the reaction is cooled,
and the solvent removed by rotary evaporation. The resulting
viscous golden oil is dried further under high vacuum at room
temperature. The resulting solid is crushed to a powder form and
analyzed. The structure of the water soluble solid is determined by
NMR to be consistent with the polymer structure shown above. The
weight average molecular weight is approximately 7400 AMU (GPC,
polysaccharide standards).
EXAMPLE 2
[0078] 6
[0079] Poly(1,4-diazabicyclo [2.2.2]
octane/.alpha.,.alpha.'-dichloro-p-xy- lene) is prepared according
to the method of Example 1, except substituting
.alpha.,.alpha.-dichloro-p-xylene for 1,4-dichloro-2-butyne. The
weight average molecular weight is approximately 8000 AMU (GPC,
polysaccharide standards).
EXAMPLE 3
[0080] 7
[0081] Poly(1,4-diazabicyclo [2.2.2] octane/1,6-dichlorohexane) is
prepared according to the method of Example 1, except substituting
1,6-dichlorohexane for 1,4-dichloro-2-butyne.
EXAMPLE 5
[0082] The effectiveness of a coagulant/flocculant/microparticle
program using the structurally rigid coagulant of this invention is
demonstrated using an analytical technique that measures the mean
chord lengths while flocculation is effected in a model system.
This measurement is performed using a commercially available
scanning laser microscope (M100F, Lasentec Corporation, Redmond,
Wash., USA). In this technique, a 780 nm diode laser is coupled
into the sample of interest via a fiber optic bundle and focused to
an elliptical beam waist of about 0.8 .mu..times.2 .mu.. The
focused beam is then scanned through the solution in a circular
motion (rotating lens) at a velocity of 2 m/s.
[0083] When the beam crosses a particle or particle floc, some of
the light is reflected back into the probe, and transmitted via
fiber optics to an avalanche photodiode detector. The duration of
time that this back-scattered light is "seen" by the detector is
proportional to the size of the particle scanned by the beam. Since
the scanning velocity of the laser is known (2 m/s), the time taken
for the laser to scan across a particle chord can be converted into
a particle chord length. The scanning velocity of the laser is much
faster than the particle velocity for all reasonable mixing
velocities of the sample (<1800 rpm), thus the measurements are
not influenced by sample flow velocities. The chord length
determination depends solely on the pulse duration of the
back-scattered light, therefore, this technique is relatively
insensitive to variations in floc reflectivity or density which is
problematic with other particle sizing techniques.
[0084] The back-scattered light signal is filtered, and the number
of individual pulses exceeding a minimum threshold signal level are
counted and binned according to their duration. The magnitude of
this signal threshold increases as the overall reflected signal
strength increases. Essentially only the single particle events
above the background reflectance intensity are used to characterize
the chord lengths. Typically 1500-3000 total pulses per second are
observed. These binned back-scattered light pulses are used to form
a histogram, where the number of observed particles per unit time
are plotted as a function of chord length. Typical histograms
contained 38 bins with chord length sizes ranging from 0.8 to 1000
microns. The histogram of the chord length distribution can be used
to calculate a variety of parameters including mean, median, mode,
and skewness.
[0085] The furnish samples used for these experiments is a 60/40
blend of drylap source hardwood and softwood Kraft pulp obtained
from a Midwestern pulp mill. These drylap source pulps are beaten
to a CSF (Canadian Standard Freeness) of 370(5) mls for the
hardwood and 374(6) mls for the softwood pulp. This mixture of
Kraft pulps is then diluted to a consistency of 0.4% by weight with
a synthetic tap water solution containing 1.50 mM CaCl.sub.2, 2.20
mM NaCO.sub.3, and 0.75 mM MgSO.sub.4. Filler (CaCO.sub.3, Omyafil,
Omya Inc.) is added at 0.1% by weight, to yield a total furnish
solids consistency of 0.5% by weight. Just prior to the experiment,
10 lbs/ton of a cationic starch (Solvitose N, Avebe) is added to
the furnish. The desired amount of the particular polymer to be
tested is then added to the reaction vessel, equipped for use with
the scanning laser microscope as follows.
[0086] The 200-mm stirrer shaft within the reaction vessel carries
a four-blade propeller. Each blade is 7 wide and 1 mm thick with a
tip-to-tip distance of 50 mm between opposite blades (diameter of
arc swept by propeller). The blades have a rectangular shape with a
pitch of 45.degree.. The bottom of the blades are set .about.1 mm
above the bottom of the mixing vessel and the top of the blades are
set .about.10 mm below the sapphire probe window. The motor shaft
rotation is clockwise so that the push of the propeller blades is
upward toward the sapphire windows. The sapphire window is at a
depth of 60 mm below the solution/air interface of the containment
beaker. The cylindrical probe (25 mm diameter) is an effective
baffle enhancing vertical mixing of the solutions.
[0087] A vessel thus modified is used in a standard Britt Jar
experiment for evaluation of treatments. For each experiment, 300
mL of the desired furnish is added to a 500 mL beaker (Pyrex No.
1040). The mixture is stirred for at least ten seconds before
initiating any trial. For the experiments where cationic
polyacrylamide is added, cationic starch is added five minutes
before the polymer addition. The starch pretreatment created a
reproducible, transient instrument response which equilibrated
after two minutes of mixing. The equilibrated starch-containing
furnish is chosen as the initial, standard state for polymer
additions and no further work examining starch effects are
explored. The probe and stirrer are wiped clean and rinsed with
deionized water between experiments. No effects related to window
fouling are observed over the time period of the experiments.
[0088] The data obtained using representative structurally-rigid
coagulants are compared to a representative coagulant in Table 1. A
higher value for mean chord length indicates that a higher amount
of flocculation has occurred. The data illustrate that the
coagulating capability of the representative rigid coagulant
polymer poly(1,4-diazabicyclo [2.2.2] octane/1,4-dichloro butyne)
is comparable to that of a conventional coagulant,
poly(epichlorohydrin/dimethylamine), yet the rigid polymers are of
much lower molecular weight. The data for poly(1,4-diazabicyclo
[2.2.2] octane/1,6-dichlorohexane) indicate that coagulating
activity is lost when a sufficiently flexible alkyl chain is
introduced into the polymer.
[0089] Also, addition of a rigid polymer to a solution is expected
to reduce solution viscosity, which is also advantageous in
treatments designed for the pulp and paper industries.
1 TABLE 1 Change in Chord Length (um) poly(Dabco .TM./DCB).sup.1
poly(Dabco .TM./DCH).sup.2 poly(Epi/DMA).sup.3 and and and Dose (#
poly(AcAm) poly(AcAm) poly(AcAm) Active/ton and and colloidal and
and colloidal and and colloidal solids poly(Ac/Am).sup.4
borosilicate.sup.5 poly(AcAm) borosilicate poly(AcAm) borosilicate
0 50.5 6.61 50.5 6.61 50.5 6.61 0.5 62.41 10.02 57.33 6.95 51.97
7.41 0.75 61.31 9.08 53.11 6.57 55.88 15.58 1.0 52.12 12.04 56.17
6.1 55.8 15.28 .sup.1coagulant poly(1,4-diazabicyclo [2.2.2]
octane/1,4-dichloro butyne). .sup.2coagulant poly(1,4-diazabicyclo
[2.2.2] octane/1,6-dichlorohexane). .sup.3coagulant
poly(epichlorohydrin/dimethylamine), available from Nalco Chemical
Company, Naperville, IL. .sup.4flocculant poly(acrylic
acid/acrylamide), available for Nalco Chemical Company, Naperville,
IL. The flocculant dose is 2 lbs/ton. .sup.5Microparticle available
from Nalco Chemical Company, Naperville, IL. The microparticle dose
is 2 lbs/ton.
[0090] 1. coagulant poly(1,4-diazabicyclo [2.2.2]
octane/1,4-dichloro butyne).
[0091] 2. coagulant poly(1,4-diazabicyclo [2.2.2]
octane/1,6-dichlorohexan- e).
[0092] 3. coagulant poly(epichlorohydrin/dimethylamine), available
from Nalco Chemical Company, Naperville, Ill.
[0093] 4. flocculant poly (acrylic acid/acrylamide), available from
Nalco Chemical Company, Naperville, Ill. The flocculant dose is 2
lbs/ton.
[0094] 5. Microparticle available from Nalco Chemical Company,
Naperville, Ill. The microparticle dose is 2 lbs/ton.
[0095] The present invention is illustrated by way of the foregoing
description and examples. The foregoing description is intended as
a non-limiting illustration, since many variations will become
apparent to those skilled in the art in view thereof. It is
intended that all such variations within the scope and spirit of
the appended claims be embraced thereby.
[0096] Changes can be made in the composition, operation and
arrangement of the method of the present invention described herein
without departing from the concept and scope of the invention as
defined in the following claims:
* * * * *