Paper making and fiber liberation – Processes and products – Non-fiber additive
Reexamination Certificate
2002-01-04
2003-02-11
Hruskoci, Peter A. (Department: 1724)
Paper making and fiber liberation
Processes and products
Non-fiber additive
C162S181600, C162S181800, C162S183000
Reexamination Certificate
active
06517677
ABSTRACT:
TECHNICAL FIELD
This invention is directed to a method of increasing retention and drainage in papermaking processes using very low molecular weight, low charge cationic dispersion polymers.
BACKGROUND OF THE INVENTION
U.S. patent application Ser. No. 09/606,581, filed Jun. 29, 2000 discloses the preparation of high molecular weight structurally-modified flocculants and their use with low molecular weight polymeric coagulants as retention and drainage aids in papermaking processes.
U.S. Pat. No. 6,313,246 discloses the preparation of high molecular weight zwitterionic flocculants and their use with low molecular weight polymeric coagulants as retention and drainage aids in papermaking processes.
U.S. Pat. No. 6,059,930 discloses the use of copolymers of (meth)acrylamide and a dialkylaminoalkyl acrylate quaternary ammonium salt, alone or in combination with one or more flocculants or coagulants as retention and drainage aids in papermaking processes.
A method of increasing retention and drainage using an anionic dispersion polymer flocculant in combination with one or more polymeric coagulants is disclosed in U.S. patent application Ser. No. 09/392,671, filed Sep. 8, 1999.
High molecular weight, high polymer actives cationic dispersion polymers for water clarification, dewatering and retention and drainage are disclosed in U.S. Pat. No. 6,171,505.
None of the foregoing references discloses the use of very low molecular weight cationic dispersion polymers as part of a retention and drainage program. Accordingly, there is a continuing need for new compositions and processes to further improve retention and drainage performance, particularly for use on the faster and bigger modem papermaking machines currently being put into use.
SUMMARY OF THE INVENTION
This invention is directed to a method for improving retention and drainage performance in a papermaking process comprising adding to a papermaking slurry an effective amount of one or more flocculants and an effective amount of one or more low molecular weight water-soluble cationic dispersion polymers, wherein the low molecular weight cationic dispersion polymer is prepared by polymerizing
a) one or more cationic monomers of formula
wherein A
1
is O or NH; B
1
is C
2
-C
4
alkylene or hydroxypropylene; R
1
is H or CH
3
, R
2
and R4 are independently C
1
-C
2
alkyl; R
3
is H, C
1
-C
2
alkyl or arylalkyl; and X
1
is an anionic counterion;
b) one or more cationic monomers of formula
wherein A
2
is O or NH; B
2
is C
2
-C
4
alkylene or hydroxypropylene; R
5
is H or CH
3
, R6 and R
7
are independently C
1
-C
2
alkyl; R
8
is arylalkyl; and X
2
is an anionic counterion;
c) one or more nonionic monomers; and
d) one or more chain transfer agents, under free radical forming conditions in an aqueous solution of an anionic salt in the presence of a stabilizer polymer, wherein the cationic dispersion polymer has a cationic charge of from about 10 mole percent to about 80 mole percent and an RSV of from about 0.2 dl/g to about 6 dl/g.
The cationic dispersion polymers of this invention have superior performance than conventional coagulants in a dual polymer retention and drainage program. The use of these polymers also avoids the unwanted addition of oils and surfactants contained in conventional latex polymers to the process water. Additionally, these polymers require no inverter system and can be introduced to the process stream using simple feeding equipment.
DETAILED DESCRIPTION OF THE INVENTION
Definitions of Terms
As used herein, the following abbreviations and terms shall have the following meanings: AcAm for acrylamide; DMAEA.BCQ for dimethylaminoethylacrylate benzyl chloride quaternary salt; DMAEA.MCQ for dimethylaminoethylacrylate methyl chloride quaternary salt; EPI-DMA for epichlorohydrin-dimethylamine; and DADMAC for diallyldimethylammonium chloride.
“(Meth)acrylate” means acrylate or methacrylate.
“(Meth)acrylamide” means acrylamide or methacrylamide.
“Papermaking process” means a method of making paper products from pulp comprising forming an aqueous cellulosic papermaking slurry, draining the slurry to form a sheet and drying the sheet. The steps of forming the papermaking slurry, draining and drying may be carried out in any conventional manner generally known to those skilled in the art.
“Monomer” means a polymerizable allylic, vinylic or acrylic compound. The monomer may be anionic, cationic or nonionic. Vinyl monomers are preferred, acrylic monomers are more preferred.
“Cationic monomer” means a monomer of formula
wherein A
1
and A
2
are independently O or NH; B, and B
2
are independently C
2
-C
4
alkylene or hydroxypropylene; R
1
and R
5
are independently H or CH
3
, R
2
, R4, R6 and R
7
are independently C
1
-C
2
alkyl; R
3
is H or C
1
-C
2
alkyl; R
8
is C
4
-C
20
alkyl or arylalkyl; and X
1
and X
2
are anionic counterions. Representative cationic monomers include dimethylaminoethylmethacrylate benzyl chloride salt (DMAEM.BCQ), dimethylaminoethylacrylate benzyl chloride salt (DMAEA.BCQ ), dimethylaminoethylacrylate methyl chloride salt (DMAEA.MCQ ), dimethylaminoethylmethacrylate methyl chloride salt (DMAEM.MCQ), dimethylaminoethylmethacrylate methyl sulfate salt (DMAEM.MSQ), dimethylaminoethylacrylate methyl sulfate salt (DMAEA.MSQ), methacrylamidopropyltrimethylammonium chloride (MAPTAC), acrylamidopropyltrimethylammonium chloride (APTAC), and the like. Dimethylaminoethylacrylate methyl chloride salt and dimethylaminoethylacrylate benzyl chloride salt are preferred.
“Nonionic monomer” means a monomer as defined herein which is electrically neutral. Representative nonionic monomers include acrylamide, methacrylamide, N-methylacrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-t-butyl(meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-methylolacrylamide, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, poly(ethylene glycol)(meth)acrylate, poly(ethylene glycol) monomethyl ether mono(meth)acrylate, N-vinyl-2-pyrrolidone, glycerol mono((meth)acrylate), 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, vinyl methylsulfone, vinyl acetate, glycidyl(meth)acrylate, and the like. Preferred nonionic monomers include acrylamide and methacrylamide. Acrylamide is more preferred.
“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, cetyl, and the like.
“Alkoxy” and “alkoxyl” mean an alkyl-O-group wherein alkyl is defined herein. Representative alkoxy groups include methoxyl, ethoxyl, propoxyl, butoxyl, and the like.
“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.
“Hydroxypropylene” means a propylene group substituted with hydroxy.
“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, halogen or haloalkyl groups. Representative aryl groups include phenyl or naphthyl, or substituted phenyl or substituted naphthyl. A preferred substituent is alkyl.
“Arylalkyl” means an aryl-alkylene-group wherein aryl and alkylene are defined herein. Representative arylalkyl include benzyl, phenylethyl, phenylpropyl, 1-naphthylmethyl, and the like. A preferred arylalkyl is benzyl.
“Halogen” means fluorine, chlorine, bromine or iodine.
“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.
“Anionic counterion” means any organic or inorganic anion which neutralizes the positive charge on the quaternary nitrogen atom of a cationic monomer as defined herein. Representative anionic counterions include halogen, sulfate, s
Cardile Richard P.
Johnson Cathy C.
Sparapany John W.
Zagala Angela P.
Breininger Thomas M.
Brumm Margaret M.
Hruskoci Peter A.
Martin Michael B.
Ondeo Nalco Company
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