ZA200505458B

ZA200505458B - Cationic or amphoteric copolymers prepared in an inverse emulsion matrix and their use in preparing cellulosic fiber compositions

Info

Publication number: ZA200505458B
Application number: ZA200505458A
Authority: ZA
Inventors: Martha Hollomon; Frank Sutman; Brian Walchuck
Original assignee: Hercules Inc
Priority date: 2002-12-06
Filing date: 2005-07-06
Publication date: 2006-04-26
Also published as: TW200420578A; CN1720267A

Description

. CATIONIC OR AMPHOTERIC COPOLYMERS PREPARED IN AN INVERSE

EMULSION MATRIX AND THEIR USE IN PREPARING CELLULOSIC FIBER

COMPOSITIONS

FIELD OF THE INVENTION

[0001] The present invention relates to water-soluble cationic and amphoteric copolymers obtained by inverse emulsion polymerization and their use in the preparation of cellulosic fiber compositions. The present invention further relates to cellulosic fiber compositions, such as paper and paperboard, which incorporate the water-soluble cationic and amphoteric copolymers.

BACKGROUND OF THE INVENTION

[0002] The making of cellulosic fiber sheets, particularly paper and paperboard, includes the following: 1) producing an aqueous slurry of cellulosic fiber; which may also contain inorganic mineral extenders or pigments; 2) depositing this slurry on a moving papermaking wire or fabric; and 3) forming a sheet from the solid components of the slurry by draining the water.

[0003] The foregoing is followed by pressing and drying the sheet to further remove water. Organic and inorganic chemicals are often added to the slurry prior to the sheet-forming step to make the papermaking method less costly, more rapid, and/or to attain specific properties in the final paper product.

[0004] The paper industry continuously strives to improve paper quality, increase productivity, and reduce manufacturing costs. Chemicals are often added to the fibrous slurry before it reaches the papermaking wire or fabric, to improve the paper machine drainage/dewatering and solids retention; these chemicals are called . retention and/or drainage aids.

[0005] As to drainage/dewatering improvement, drainage or dewatering of the fibrous slurry on the papermaking wire or fabric is often the limiting step in achieving faster paper machine speeds. Improved dewatering can also result in a drier sheet in the press and dryer sections, resulting in reduced energy consumption. In addition, this is the stage in the papermaking method that determines many sheet final properties.

[0006] With respect to solids retention, papermaking retention aids are used to ) increase the retention of fine furnish solids in the web.during the turbulent method of draining and forming the paper web. Without adequate retention of the fine solids, they are either lost to the mill effluent or accumulate to high levels in the recirculating white water loop, potentially causing deposit buildup. Additionally, insufficient retention increases the papermakers' cost due to loss of additives intended to be adsorbed on the fiber to provide the respective paper opacity, strength, or sizing properties.

[0007] High molecular weight (MW) water-soluble polymers with either cationic or amphoteric charge have traditionally been used as retention and drainage aids.

Recent development of inorganic microparticles, known as microparticulate retention and drainage aids, in combination with high MW water-soluble polymers, have shown superior retention and drainage efficacy compared to conventional high MW water-soluble polymers. U.S. Patent Nos. 4,294,885 and 4,388,150 teach the use of starch polymers with colloidal silica. U.S. Patent No. 4,753,710 teaches flocculating the pulp furnish with a high MW cationic flocculant, inducing shear to the flocculated furnish, and then introducing bentonite clay to the furnish. U.S. Patent Nos. 5,274,055 and 5,167,766 disclose using chemically cross-linked organic micropolymers as retention and drainage aids in the papermaking process.

[0008] Copolymers are also used to control deposition of contaminants or organic deposits in papermaking systems. Organic deposits is a term used to described tacky, water insoluble materials in the papermaking system that are detrimental to the production of paper. Such materials derived from trees during the pulping and papermaking process are termed pitch or wood pitch, while the term stickies is used to describe contaminants that are derived from adhesives or coatings introduced into the papermaking process as a contaminant of recycled fiber. One strategy for ) eliminating these materials is to agglomerate the organic deposits into larger, non- tacky particles that can be removed from the papermaking stock or incorporated into the sheet without causing deposits in the papermaking system of defects in the sheet. Chemicals that are able to interact with organic deposits and mitigate their negative impact include surfactants and polymers. The polymers can be ionic or nonionic, and includes materials used as flocculants, coagulants and dispersants.

[0009] The efficacy of the polymers or copolymers used will vary depending upon the type of monomers from which they are composed, the arrangement of the monomers in the polymer matrix, the molecular weight of the synthesized molecule, ) and the method of preparation. lt is the latter characteristic that is a focus of the present invention.

[0010] Specifically, it has been unexpectedly discovered that water-soluble cationic and amphoteric copolymers when prepared under certain conditions exhibit unique physical characteristics. Additionally, said copolymers provide unanticipated activity in certain applications including papermaking applications such as retention and drainage aids and contaminant control aids. Although the synthesis methods employed are generally known to those skilled in the art, there is no prior art suggesting that the unique physical characteristics and unanticipated activity observed would result.

SUMMARY OF THE INVENTION

[0011] The present invention is directed to water soluble cationic and amphoteric copolymers and cellulosic fiber compositions containing the copolymer, particularly a cellulosic sheet such as paper or paperboard. The invention is also directed to a method for making the copolymer and the cellulosic fiber compositions.

[0012] In another aspect, the present invention provides a method of making a cellulosic fiber composition comprising adding, to a cellulose pulp slurry, a water- soluble cationic or amphoteric copolymer of Formula | or Formula li below. The invention further relates to cellulosic fiber compositions, including an aqueous slurry of cellulosic pulp, containing such water-soluble cationic or amphoteric copolymers.

As used herein, the term copolymer is understood to be polymer compositions consisting of two or more different monomeric units.

[0013] In accordance with the present invention, it has been unexpectedly discovered that certain cationic and amphoteric copolymers exhibit unique physical ) characteristics and provide unanticipated activity when prepared employing certain polymerization conditions. The cationic and amphoteric copolymers of the invention are obtained from inverse (water-in-oil) emulsion polymerization. For cationic copolymers one or more water-soluble monomers, in particular one or more cationic monomers are used in the emulsion polymerization. For amphoteric copolymers one or more cationic monomers and one or more anionic monomers are used in the emulsion polymerization. The resulting cationic and amphoteric copolymers are water-soluble.

[0014] The cationic copolymers of the invention have the formula:

FB-co-C+ (Formula 1) wherein B is a nonionic polymer segment formed from the polymerization of one or more nonionic monomers; C is an cationic polymer segment formed from polymerization of one or more ethylenically unsaturated cationic monomers; the molar % ratio B:C is from 1:99 to 99:1; and “co” is a designation for a polymer system with an unspecified arrangement of two or more monomer components.

Furthermore, the preparation is conducted in a fashion, absent cross-linking agents and via a water-in-oil emulsion procedure, such that the Huggins’ constant (kK) determined in 0.01M NaCl is greater than 0.5 and the storage modulus (G') for a 3.0 wt. % actives polymer solution at 6.3 Hz is greater than 50 Pa.

[0015] The amphoteric copolymers of the invention have the formula: §B-co-C-co-A} (Formula Il) wherein B is a nonionic polymer segment formed from the polymerization of one or more nonionic monomers; C is an cationic polymer segment formed from polymerization of one or more ethylenically unsaturated cationic monomers; Ais an anionic polymer segment formed from polymerization of one or more ethylenically unsaturated anionic monomers; the minimum molar % of any of B, C, or A used to from the polymer is 1% and the maximum molar % of any of A, B and C is 98%; and “co” is a designation for a polymer system with an unspecified arrangement of two or more monomer components. Furthermore, the preparation is conducted in a ] fashion, absent cross-linking agents and via a water-in-oil emulsion procedure, such that the Huggins’ constant (k') determined in 0.01M NaCl is greater than 0.5 and the . storage modulus (G’) for a 1.5 wt. % actives polymer solution at 6.3 Hz is greater than 50 Pa. 4 - N

DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention provides for water-soluble cationic and amphoteric copolymers with unique physical characteristics, methods of making the copolymers, ) and methods of making cellulose fiber compositions that comprise adding the water- soluble cationic and amphoteric copolymer to a cellulose pulp slurry. The general structure of the water-soluble cationic copolymer of the present invention is provided in Formula I. The general structure of the amphoteric copolymers of the invention is provide in Formula Il.

FB-co-C} (Formula I)

FB-co-C-co-A}- (Formula Il)

[0017] The nonionic polymer segment B in Formula | and Formula Il is the repeat unit formed after polymerization of one or more nonionic monomers. Exemplary monomers encompassed by B include, but are not limited to, acrylamide; methacrylamide; ~~ N-alkylacrylamides, such as N-methylacrylamide; N,N- dialkylacrylamide, such as N,N-dimethylacrylamide; methyl methacrylate, methyl acrylate; acrylonitrile; N-vinyl methylacetamide; N-vinylformamide; N-vinylmethyl formamide; ; vinyl acetate; N-vinyl pyrrolidone, mixtures of any of the foregoing and the like. The invention contempts that other types of nonionic monomer can be used.

[0018] The cationic polymer segment C in Formula | and Formula Il is the repeat unit formed after polymerization of one or more cationic monomers. Exemplary monomers encompassed by C include, but are not limited to, cationic ethylenically unsaturated monomers such as the diallyldialkylammonium halides, such as diallyldimethylammonium chloride; the (meth)acrylates of dialkylaminoalkyl compounds, such as dimethylaminoethyl (meth)acrylate, diethylaminoethy! (meth)acrylate, dimethyl aminopropy! (methacrylate, 2-hydroxydimethyl aminopropyl ) (meth )acrylate, aminoethyl (meth)acrylate, and the salts and quaternaries thereof; the N,N-dialkylaminoalkyl(meth)acrylamides, such as N,N- dimethylaminoethylacrylamide, and the salt and quaternaries thereof and mixture of the foregoing and the like.

[0019] The anionic polymer segment A in Formula ll is the repeat unit formed after polymerization of one or more anionic monomers. Exemplary monomers - .

encompassed by A include, but are not limited to, the free acids and salts of acrylic acid, methacrylic acid; maleic acid: itaconic acid; acrylamidoglycolic acid; 2- acrylamido-2-methyli-1-propanesulfonic acid: 3-allyloxy-2-hydroxy-1-propanesulfonic : acid; styrenesulfonic acid; vinylsulfonic acid: vinylphosphonic acid; 2-acrylamido-2- methylpropane phosphonic acid; mixtures of any of the foregoing and the like.

[0020] The molar percentage of B:C of nonionic monomer to cationic monomer of

Formula | may fall within the range of about 99:1 to 1:99, or about 99:1 to about 50:50 or about 95:5 to about 50:50, or about 95:5 to about 75:25, or 90:10 to 60:40, preferably the range is from about 95:5 to about 60:40 and even more preferably the range is from about 90:10 to about 70:30. In this regard, the molar percentages of B and C must add up to 100%. It is to be understood that more than one kind of nonionic monomer may be present in Formula 1. It is also to be understood that more than one kind of cationic monomer may be present in Formula I.

[0021] With respect to the molar percentages of the amphoteric polymers of Formula ll, the minimum amount of each of A, B and C is about 1% of the total amount of monomer used to form the polymer. The maximum amount of A, B or C is about 98% of the total amount of monomer used to form the polymer. Preferably the minimum amount of A is about 5%, more preferably the minimum amount of A is about 7% and even more preferably the minimum amount of each of A is about 10% of the total amount of monomer used to form the polymer. Preferably the minimum amount of each of B is about 5%, more preferably the minimum amount of B is about 7% and even more preferably the minimum amount of B is about 10% of the total amount of monomer used to form the polymer. Preferably the minimum amount of each of C is about 5%, more preferably the minimum amount of C is about 7% and even more preferably the minimum amount of C is about 10% of the total amount of monomer used to form the polymer. Preferably the amount of C (the cationic polymer segment) in the final polymer is not more than about 50% of the total, even more preferably not more than about 40% of the total. Preferably the amount of A (anionic polymer segment) in the final polymer is not more than about 80, more preferably not more than about 70% and even more preferably not more than about 60%. In this regard, the molar percentages of A, B and C must add up to 100%. It is to be understood that more than one kind of nonionic monomer may be present in Formula

I, more than one kind of cationic monomer may be present in Formula Il, and that more than one kind of anionic monomer may be present in Formula I.

[0022] In one preferred embodiment of the invention the water-soluble cationic or amphoteric copolymer is defined where B, the nonionic polymer segment, is the repeat unit formed after polymerization of acrylamide. y [0023] In another preferred embodiment of the invention the water-soluble amphoteric copolymer is defined where B, the nonionic polymer segment, is the ’ repeat unit formed after polymerization of acrylamide and A is a salt of acrylic acid.

[0024] When a salt form of an acid is used to make an amphoteric polymer it is preferred that the cation of the salt is selected from Na* , K* or NH, *.

[0025] It is also an aspect of this invention that the water-soluble cationic and amphoteric copolymers are prepared in such a fashion that the resulting polymers exhibit unique physical characteristics and provide unanticipated activity. The resulting water-soluble cationic and amphoteric copolymer is not considered to be a cross-linked polymer in that no cross-linking agent is utilized in the preparation. It is thought that small amounts of cross linking agent should not significantly affect the polymer properties of the present invention. The physical characteristics of the water-soluble cationic and amphoteric copolymers are unique in that their Huggins’ constant (k') as determined in 0.01M NaCl is greater than 0.5 and the storage modulus (G’) for a 1.5 wt. % actives amphoteric polymer solution or 3.0 wt% actives for a cationic polymer solution, at 6.3 Hz is greater than 50 Pa, preferably greater than 75 and even more preferably greater than 100, or greater than 175, or greater than 200, or greater than 250. The Huggins' constant is greater than 0.5, preferably greater than 0.6, or greater than 6.5, or greater than 0.75, or greater than 0.9, or greater than 1.0.

[0026] Preferably the water-soluble cationic and amphoteric copolymers of the present invention are prepared by an inverse (water-in-oil) emulsion polymerization technique. Such processes are known to those skilled in the art, for example see

U.S. Pat. No. 3,284,393, and Reissue U.S. Pat. Nos. 28,474 and 28,576, herein incorporated by reference. Preparation of an aqueous solution from the emulsion polymer may be effected by inversion by adding the emuision polymer to water, wherein the emulsion or water may also contain a breaker surfactant. Breaker surfactants are additional surfactants that are added to an emulsion to promote inversion. The resulting copolymers may also be further isolated by precipitating in an organic solvent such as acetone and dried to a powder form or spray drying to a powder form. The powder can be easily dissolved in an aqueous medium for use in desired applications.

[0027] In general, an inverse emulsion polymerization process is conducted by 1) . preparing an aqueous solution of the monomers, 2) adding the aqueous solution to a hydrocarbon liquid containing appropriate surfactant or surfactant mixture to form an ’ inverse monomer emulsion, 3) subjecting the monomer emulsion to free radical polymerization, and 4) optionally adding a breaker surfactant to enhance the inversion of the emulsion when added to water.

[0028] Polymerization of the emulsion may be carried out in any manner known to those skilled in the art. Initiation may be effected with a variety of thermal and redox free-radical initiators including azo compounds such as azobisisobutyronitrile and the like. Polymerization may also be effected by photochemical irradiation processes, irradiation or by ionizing radiation with a **Co source.

[0029] Preferred initiators are oil soluble thermal initiators. Typical examples include, but are not limited to, 2,2'-azobis-(2,4-dimethylpentanonitrile); 2,2'- azobisisobutyronitrile (AIBN); 2,2'-azobis-(2,-methylbutanonitrile); 1,1'-azobis- (cyclohexanecarbonitrile); benzoyiperoxide, lauryl peroxide and the like.

[0030] Any of the chain transfer agents known to those skilled in the art may be used to control the molecular weight. Those include, but are not limited to, lower alkyl alcohols such as isopropanol, amines, mercaptans such as mercaptoethanol, phosphites, thioacids, allyl alcohol, and the like.

[0031] The aqueous solution typically comprises an aqueous mixture of nonionic monomer or mixtures of nonionic monomers, and a cationic monomer or mixtures of cationic monomers. For the amphoteric copolymer, the aqueous solution typically comprises an aqueous mixture of nonionic monomer or mixtures of nonionic monomers, a cationic monomer or mixtures of cationic monomer and an anionic monomer or mixtures of anionic monomers. The aqueous phase may also comprise such conventional additives as are desired. For example, the mixture may contain chelating agents, pH adjusters, initiators, chain transfer agents as described above, and other conventional additives. For the preparation of the water-soluble cationic and amphoteric copolymer materials the pH of the aqueous solution is from about 2 to about 12 and is preferably equal to or greater than 2 and less than 10, more preferably the pH is greater than 2 and less than 8 and even more preferably, the pH is from about 3 to 7 and most preferably the pH is about 4 to about 6.

Claims

CLAIMS:

1. A water-soluble copolymer composition comprising the formula of I: FB—co—C4 wherein B is a nonionic polymer segment formed from the polymerization of one or more ethylenically unsaturated nonionic monomers: C is a cationic polymer segment formed from polymerization of one or more ethylenically unsaturated cationic monomers, the molar % ratio of B:C is from 99:1 to 1:99; and the water-soluble cationic copolymer is prepared via a water-in-oil emulsion polymerization technique that employs at least one emulsification surfactant consisting of at least one diblock or triblock polymeric surfactant wherein the amount of the at ieast one diblock or triblock surfactant to monomer is at least about 3 :100 and wherein; the water-in-oil emulsion polymerization technique comprises the steps: preparing an aqueous solution of monomers, adding the aqueous solution to a hydrocarbon liquid containing surfactant or surfactant mixture to form an inverse emulsion, causing the monomer in the emulsion to polymerize by free radical polymerization at a pH range of from about 2 to less than 7; and wherein said copolymer having a Huggins’ constant (k’) is greater than 0.5; and said copolymer having a storage modulus (G’) greater than 50 Pa.

2. The water soluble copolymer composition of claim 1 wherein the copolymer further comprises an anionic polymer segment, "A", wherein A is an anionic polymer segment formed from polymerization of one or more : ethylenically unsaturated anionic monomers; and the minimum amount of A is 1% of the total amount of monomer used to form the polymer.

3. The composition of claim 1 wherein the ratio of B:C is about 99:1 to about 50:50.

4, The composition of claim 3 wherein the ratio of B:C is about 95:5 : to about 50:50.

5. The composition of claim 2 wherein the minimum amount of each of A,B and C is 5%.

6. The composition of claim 5 wherein the minimum amount of each of A,B and Cis 7%.

7. The composition of any of claims 2, 5 or 6 wherein A is selected from the group consisting of the free acids and salts of acrylic acid; methacrylic acid; maleic acid; itaconic acid; acrylamidoglycolic acid; 2-acrylamido-2-methyl- 1-propanesulfonic acid; 3-allyloxy-2-hydroxy-1-propanesulfonic acid; styrenesulfonic acid; vinylsulfonic acid; vinylphosphonic acid; 2-acrylamido-2- methylpropane phosphonic acid; mixtures of any of the foregoing.

8. The composition of any of the preceding claims 1 to 6 wherein B is selected from the group consisting of acrylamide, methacrylamide; N- alkylacrylamides, N,N-dialkyl-acrylamide; methyl methacrylate, methyl acrylate; acrylonitrile; N-vinyl methylacetamide; N-vinylformamide; N-vinylmethyl formamide; vinyl acetate; N-vinyl pyrrolidone; and mixtures of any of the foregoing.

.

9. The composition of any of the preceding claims 1 to 6 wherein C is selected from the group consisting of diallyldialkylammonium halides, ) (meth)acrylates of dialkylaminoalkyl compounds, such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethyl aminopropyl (meth)acrylate, 2-hydroxydimethyl aminopropyl (methacrylate, aminoethyl (meth)acrylate, and the salts and quaternaries thereof, the N,N-

i WO 2004/052942 PCT/US2003/039034 dialkylaminoalkyl(meth)acrylamides, such as N,N- dimethylaminoethylacrylamide, and the salt and quaternaries thereof and

. mixtures of any of the foregoing.

10. The composition of claim any of the preceding claims 1 to 9 wherein the diblock or triblock surfactant is a copolymer based on polyester derivatives of fatty acids and poly[ethyleneoxide].

11. The composition of any of the preceding claims 1 to 10 wherein diblock or triblock surfactant to monomer ratio is at least about 4:100.

12. The composition of any of the preceding claims 1 to 11 wherein the emulsification surfactant consists of a blend of a polymeric surfactant comprising one or two polymeric components derived from oil-soluble complex monocarboxylic acid and a water-soluble component derived from polyalkylene glycol, and sorbitan monooleate; and 2,2’-azobisisobutyronitrile is employed as the free radical initiator.

13. The composition of any of the preceding claims 1 to 12 wherein the surfactant system has a combined Hydrophilic-Lipophilic Balance of less than 8.

14. The composition of any of the preceding claims 1 to 13 wherein the diblock or triblock surfactant is a copolymer based on polyester derivatives of fatty acids and poly[ethyleneoxide].

15. The composition of any of the preceding claims 1 to 14 wherein k' is greater than 0.6. 28 - i

PCT/US2003/039034

16. The composition of any of the preceding claims 1 to 15 wherein G’ is greater than 75.

17. The composition of any of the preceding claims 1 to 16 further comprising cellulose fiber.

18. A method of making cellulose fiber composition which comprises adding to a cellulose pulp slurry the water-soluble cationic copolymer of any of the preceding claims 1to 17.

19. A composition according to any one of claims 1 to 17, substantially as herein described and illustrated.

20. A method according to claim 18, substantially as herein described and illustrated.

21. A new composition, or a new method of making a composition, substantially as herein described. AMENDED SHEET