CA2205277A1 - Combination of talc-bentonite for deposition control in papermaking processes - Google Patents
Combination of talc-bentonite for deposition control in papermaking processesInfo
- Publication number
- CA2205277A1 CA2205277A1 CA002205277A CA2205277A CA2205277A1 CA 2205277 A1 CA2205277 A1 CA 2205277A1 CA 002205277 A CA002205277 A CA 002205277A CA 2205277 A CA2205277 A CA 2205277A CA 2205277 A1 CA2205277 A1 CA 2205277A1
- Authority
- CA
- Canada
- Prior art keywords
- suspension
- talc
- bentonite
- added
- pitch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/02—Agents for preventing deposition on the paper mill equipment, e.g. pitch or slime control
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
- D21H17/68—Water-insoluble compounds, e.g. fillers, pigments siliceous, e.g. clays
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S162/00—Paper making and fiber liberation
- Y10S162/04—Pitch control
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Abstract
A method for minimizing pitch, ink, and stickies particle deposits in the paper making process by causing the retention of such particles onto fiber, comprising the steps of adding an effective pitch, ink, and stickies controlling amount of talc to a suspension of fiber in contact with the paper machine and associated parts and adding an effective pitch, ink, and stickies controlling amount of bentonite to the suspension, thereby increasing retention of pitch, ink, and stickies onto the fiber and minimizing the deposition of pitch, ink, and stickies particles on the paper machine and associated parts.
Description
CA 0220~277 1997-0~-13 FIELD OF THE INVENTION
A method for minimi~ing pitch, ink, and stickies particle deposition in the paper making process compri~ing the steps of adding an effective pitch, ink, and stickies controlling amount of talc and bentonite to the fiber suspension and adding an effective pitch, ink, and siickies controiiing amount of bentonite to the suspension, thereby reducing the pitch, ink, and stickies particle deposition in the paper making process.
BACKGROUND OF THE INVE~TION
The problem of pitch, ink, stickies particle deposition control in the paper making 10 process for all types of paper has previously been recognized. The pitch in the fibers of wood pulps is associated with naturally occurring lignin dispersing agents. Cooking and mechanical agitation which occur during the pulping by the sulfate process liberate pitch and these natural dispersing agents. However, as a result of the mechanical work on the fibers~ the natural dispersing agents liberated along with the pitch are inadequate to keep 15 the pitch from depositing on the equipment employed in beating, hydrating, refining, bleaching~ and even on the wire used for forming the sheet.
Because of the tendency of the pitch to agglomerate within the pulp suspension or deposii on ihe surfaces of the wire or other equipment, the pitch frequently causes the formation of spots or holes in the sheet formed. Additionally, the pitch may adhere to the 20 wire or press rolls or dryer rolls and cause tearing of the sheet. The result of the pitch cont~min~tion is the production of sheets with numerous imperfections. Among other consequences of pitch particle deposition are the expense of cleaning the m~c.hinery CA 0220~277 1997-0~-13 frequently either with solvents or steam, and the loss of produetion during cleaning and replaeing operations eaused by breakdown of the sheet.
Organie eont~min~nts, sueh as ink and adhesives whieh are present in recycled paper, can have a sticky or tacky nature. The problems of h~nrlling such eont~min~nts, 5 referred to as ink and stiekies, is similar to the problems eneountered with pitch.
Water soluble polymers, and in particular, cationie water soluble polymers, have been used in the production of paper for a number of purposes. Water soluble polymers have been added to pulps to improve fine and filler retention. In another instance, these polymers have been used to improve drainage of water from the pulp as it is formed into 10 a sheet on wires or felts. Polymers have also been used to attaeh piteh particles to cellulose fibers while they were in a colloidal state thereby preventing them from agglomerating and accumulating on the surfaces of production equipment. Polymers also have been used for improved efficiency in retaining fillers, such as clays.
In the case of cationic polymeric coagulants, it is necessary to combine them with i S flocculants to make their performance acceptable. Examples of cationic polymers used for pitch retention, see (~n~ n Patent Applications, 1,150,914 and 1,194,254, the disclosures of which are incorporated herein by reference. These applications disclose cationic polymers which give superior colloidal pitch particle reduction in aqueous pulps such as polyquaternary polymers of essentially linear structure consisting of essentially of 20 a difunctional reaction product of a lower dialkylamine and a difunctional epoxy compound selected from the group consisting of epihalohydrins, diepoxide, precurors of epihalohydrins and diepoxides. and poly-diallyldimethyl ammonium chloride, CA 0220~277 1997-0~-13 respectively. See also U.S. Patent No. 5,098,520 and allowed U.S. Patent Application No. 08/148,069, the disclosure of which is incorporated herein by reference.
Previous products used for this purpose have included low molecular weight polymers of DADMAC, epichlorohydrin ~ mine polymers or other polyamines 5 including polyethyleneimine. Due to the low molecular weight, these products were often less effective as retention aids and in some cases had to be supplemented with a high molecular weight flocculant to achieve their desired level of retention. Flocculants by themselves failed to give adequate retention of colloidal m~tçri~l~, often hurting machine runability.
The paper making process, particularly the production of newsprint, presents a challenge to the paper maker with respect to optimi7ing production. It is increasingly common to use recycled fiber rather than virgin fiber in n~w~lhlt furnish. Due to the nature of newsprint and the necessity to carefully control costs, problems such as retention, drainage and pitch, ink, and stickies particle deposition control must be solved 15 economically. It would represent an advance in the art if newsprint mills, as well as other paper mills, could use one product which could solve or improve the several problems described above.
In recent years, the use of retention programs using inorganic "microparticles" has gained acceptance. Microparticle programs are defined not only by the use of a 20 microparticle component but also by the addition points of chemicals in relation to shear.
In order to be effective, conventional retention and drainage programs require incorporation of some higher molecular weight component as part of the program. In conventional programs, the high molecular weight component is added after a high shear CA 0220~277 1997-0~-13 point in the stock flow system leading up to the headbox of the paper m~chine. Flocs that are forrned by addition of the high molecular weight component are broken down to some extent by the high shear. Since these flocs are formed primarily by the bridging mech~ni~m, this breakdown is largely irreversible and flocs do not re-form to any 5 significant extent. For this reason, most of the retention and drainage performance of the flocculant is lost by feeding it before a high shear point. Additionally, a need for feeding the high molecular weight polymer after the high shear point often leads to formation problems. The feeding requirements of the high molecular weight polymers and copolymers which provides improved retention often leads to a col.lplolllise in formation.
In the microparticle retention programs, high molecular weight polymer is added before at least one high shear point. An inorganic, particulate material is then added to the furnish after the stock has been flocculated with the high molecular weight component and subjected to shear. The microparticle, usually highly negatively charged, is added to a furnish pretreated with some cationic material [e.g., starch, coagulant, alum, cationic flocculant] so that the primary mechanism of operation appears to be an electrostatic interaction. The microparticle addition re-flocculates the furnish, resulting in retention and drainage that is at least as good as that attained using the high molecular wei~ht component in the conventional way (after shear), with no deterious impact on formation .
One such program employed to provide an improved combination of retention and dewatering is described in United States Pat. Nos. 4,753,710 and 4,913,775, inventors Langley et al.. issued respectively June 28, 1988 and April 3, 1990, incorporated hereunto by ref'erence. In the disclosed method. a high molecular weight linear cationic polymer is CA 0220~277 1997-0~-13 added to the aqueous cellulosic paper making suspension before shear is applied to the suspension, followed by the addition of bentonite after the shear application. Shearing is generally provided by one or more of the cleaning, mixing and pumping stages of the paper making process, and the shearing breaks down the large flocs formed by the high 5 molecular weight polymer into microflocs, and further agglomeration then ensues with the addition of the bentonite clay particles.
The treatment of an aqueous cellulosic slurry with a high molecular weight cationic polymer followed by shear, preferably a high degree of shear, is a wet-end treatment in itself known in the field, for instance as described in aforesaid United States Pat. Nos. 4,753,710 and 4,913,775, inventor Langley et al., issued respectively June 28, 1988, and April 3, 1990, incorporated herein by reference.
Other such programs are based on the use of colloidal silica as a microparticle in combination with cationic starch (Sunden et al., U. S. Pat. No. 4,388,150 issued on June 14, 1983) known as Composil (Eka Nobel) or cationic starch and flocculant combination (Johnson, U.S. Pat. No. 4,643,801 issued on February 17, 1987) and known as Positek (Nalco). Since the onset of the microparticle-based technology, a number of other, synthetic organic microparticles have been developed and introduced to the market.
Talc and bentonite are widely used in the paper industry. Talc is primarily used as a pitch control agent and more recently for stickies control in recycled fibre. Bentonite is 20 often used as part of a retention program. Using the two components together in dry form or as a slurry prior to delivery to the mill offers several advantages from both a perforrnance and a handling points of view.
CA 0220~277 1997-0~-13 The present invention is predicated upon the discover.v that talc used in combination with bentonite is capable of improving pitch, ink, and stickies particle retention to the fiber, thereby minimi7in~ the deposition of pitch, ink, and stickies particles on the surfaces of the paper m~chine and associated parts (structures) which include, felts, pipes, wires, pumps, tanks, and the like in the production of all types of paper.
SUMMARY OF THE INVENTION
The invention is a method for minimi7inp; pitch, ink, and stickies deposition in the 10 paper making process by causing the retention of such particles onto fiber, comprising the steps of adding an effective pitch, ink, and stickies controlling amount of taic to a suspension of fiber in contact with the paper machine and associated parts and adding an effective pitch, ink, and stickies controlling amount of bentonite to the suspension in contact with the paper machine and associated parts, thereby increasing retention of pitch, 15 inl;, and stickies onto the fiber and minimi7.ing pitch, ink, and stickies particles deposition on the paper machine and associated parts.
The bentonite and talc may be added to the separately to the paper making suspension in any order of addition. Additionaiiy, the bentonite and the taic may aiso be added simultaneously to the suspension in contact with the paper machine and associated 20 parts. The ratio of bentonite to talc is preferably from about 1:1 to about 0.1:20, more preferably from about 1:1 to 0.1:10, and most preferably from about 1:1 to 1:5.
, ' CA 0220~277 1997-0~-13 DESCRIPTION OF THE INVENTION
The invention comprises a method for improving the paper making process, particularly the production of n~w~l lh~t, filled n~w~,hl~, coated paper, all grades cont~ining mechanical pulp, board paper, by improving the pitch and stickies control in 5 the pulp and paper making process. The pitch, ink, stickies formation and deposits are minimize~l and in some cases elimin~terl Specifically, it comprises adding an effective pitch, ink, and stickies controlling amount of bentonite having a high swelling capacity in water to a suspension of fiber in contact with the paper m~hine and associated parts, and then, an effective pitch, ink, and stickies controlling amount of talc is also added to the 10 suspension in contact with the paper machine and associated parts, thereby increasing retention of pitch, ink, and stickies onto the fiber and minimi7inp the deposition of pitch, ink, and stickies particles on the paper machine and associated parts.
Bentonite is a colloidal clay, commercially available, composed predomin:~ntly of montmorillonite. The Wyoming or Western variety of bentonite is a sodium bentonite 15 which has a high water swelling capacity. The Southern variety is a calciurn bentonite with negligible swelling capacity. The bentonite can be any of the materials commercially referred to as bentonites or bentonite-type clays. Preferably, the bentonite is of the type having a high swelling capacity in water, such as sodium potassiurn bentonite. Bentonite clay has the desirable property of being thixo-tropic and shear 20 thinning, i.e.. it forms a network which is easily destroyed by the application of shear, but then reforms when shear is removed.
The dry particle size of the bentonite is preferably at least 90 % below 100 microns and most preferably at least 60 % below 50 microns. The surface area of the CA 0220~277 1997-0~-13 bentonite partieles before swelling is preferably at least 30 and more preferably at least 50, and most preferably between 60 to 90 m2/gm. The surface area after swelling is preferably between 400 and 800 m2/gm. The ~,cr~l,cd type of the bentonite swells at least 15 or 20 times. The partiele size after swelling is preferably at least 90 % below 2 5 mierons.
Tale, an inexpensive material, commercially available, which is commonly used for pitch, ink and stickies deposition control in pulp and paper mills, is a crystalline powder of a natural hydrous m~gnesium silicate. The crystallographic structure of talc results in a platelet-like appearance. The edges of these platelets are hydrophilic, and as 10 such is responsible for the dispersability of talc in water. The hydrophobic faces of the platelets are able to interact with hydrophobic substances, such as pitch and stickies particles.
Colloidal pitch adsorbs onto the hydrophobic faces of the talc crystal, thereby preventing the formation of large pitch agglomerates. "Detackification", a ch~nging of 15 the surface properties of pitch and stickies particles, is recognized as the operating mechanism of talc. The talc/pitch particles are retained in the fiber mat as its forms, thereby preventing the recirculation, concentration and eventual deposition of these particles in the system.
However, the exposure of the talc/pitch agglomerate to shear will often create a 20 fresh, sticky surface which can cause deposit problems further on in the paper m~kin~
process. Other disadvantages to using talc include the high talc dosage rates often required to give good pitch, ink, and stickies deposition control and its abrasiveness which decreases the useful life of paper machine components such as wires, pick-up rolls CA 0220~277 1997-0~-13 and felts. At the high dosages of talc, a very effective retention program must be in place or wire and felt plugging in the press section of a paper m~hine will occur. However, high dosages of talc can also increase the slipperiness of the sheet formed, resulting in problems during the process of winding and in the printing presses. At low dosages of S talc, the deposition of pitch and stickies particles possible as well as the talc itself becoming a part of the deposit thereby increasing the mass of deposit formed during the paper making process.
The use of talc in combination with bentonite (or b~ onile and a treatment polymer used to improve the retention capacity in a furnish) allows a reduction in the 10 dosage of talc while producing an effective pitch and stickies control program and avoiding the disadvantages of high talc dosage rates such as felt plugging and slipperiness problems. Bentonite increases the retention of talc particles. Complete retention of pitch and stickies particles in the formed web of paper is most likely not possible. Therefore, the addition of a small amount of talc in combination with bentonite or a 15 bentonite/treatment polymer program will allow detackification of the rem~ining unretained pitch particles.
The term "paper machine", as used herein, includes felts, pumps, wires, tanks, pipes and similar associated parts as well as all metal surfaces where the fiber suspension contacts the surface of the paper machine. The term "suspension" as used herein includes 20 pulp, fiber suspended in water, furnishes and the like.
The talc may be added to the suspension before the bentonite is added to the suspension. In another embodiment, the bentonite and the talc may be added simultaneously to the suspension in contact with the paper machine and associated parts.
-CA 0220~277 1997-0~-13 In addition, the bentonite and talc may be added as a mixture. The bentonite and talc can be mixed together in the powdered form. This may be done on-site, but likely off-site at the point where one or the other is mined or manufactured. Bentonite and talc have similar requlrements for pLe~alillg a slurry of either in terms of mixing. Preparing a 5 slurry of the mixture will therefore require less equipment and also make feeding and metering easier, making the invention easier to practice.
The ratio of bentonite to talc is preferably from about 1:1 to 0.1:20, more preferably from 1:1 to 0.1:10, and most preferably from about 1:1 to 1:5.
The talc/bentonite treatment program may be added to paper making systems to 10 improve pitch, ink, and stickies control. This talclbentonite tre~tment program is also effective in treating newsprint made from either virgin or recycled fibers. It is understood that the term, "newsprint" as used herein includes other grades of paper which contain mechanical pulp~ recycled or deinked pulp.
The talc and bentonite are added to the pulp slurry (suspension). Both bentonite 15 and talc. added separately or as a mixture, can be fed at any point to the paper making process or suspension, at any point in the paper machine. In addition, the bentonite and talc. added separately or as a mixture. can be added as a dry powder or as a hydrated suspension obtained by dispersing powdered material in water.
Since both bentonite and talc require hydration prior to injection into the paper 20 mal;ing system. delivering them to the site as a mixture and hydrating the mixture in the same tanli is advantageous in reducing the amount of mechanical equipment required to perforrm the hydration.
CA 0220~277 1997-0~-13 Dosages of Bentonite and Talc Bentonite Talc 0.05 - 10 0.05 - 20 0.1 - 5 0.5 - 10 0.5-3 1-5 The invention can be used in the presence of any effective retention program applied in the mill. An effective retention program is required to provide retention of 10 talc, which if unretained could cause felt plugging problem. It would be preferable to use the invention in the presence of a retention program wherein the retention of the talc would be benefited. A wide variety of chemistries are known in the art to work as retention agents, including polymeric materials. Examples of the polymeric material that can be used as a retention program include acrylamide homopolymers, copolymers, 15 terpolymers, and so on.
The polymers useful in the practicing of this invention contain at least one of the monomers chosen from the group consisting of acrylamide, methacrylamide, N-tertiary butyl acrylamide, 2-acrylamido-2-methylpropane sulfonate, sulfomethyl acrylamide, sulfomethyl methacrylamide~ sulfoethylacrylamide, and the like. In addition, the 20 polymeric retention material may also be the difunctional reaction product of a lower dialkylamine and a difunctional epoxy compound selected from the group consisting of epihalohydrins, diepoxide, precurors of epihalohydrins and diepoxides, as well as poly-diallyldimethyl ammonium chloride.
CA 0220~277 1997-0~-13 The polymers used in the application of this invention are generally selected from, however, not limited to, following examples. These polymers belong to one of the three classes: nonionic, anionic and cationic. The nonionic polymers are homopolymers or copolymers of nonionic monomers. The plef~.,ed nonionic monomer is acrylamide or 5 methacrylamide and pler~lled nonionic polymers are polyacrylamide and polymethacrylamide.
By the term of cationic retention polymers, it is understood to include any water-soluble copolymer of (meth)acrylamide which carries or is capable of carrying the cationic charge when dissolved in water, whether or not this charge-carrying capacity is 10 dependent upon pH. The cationic copolymers of (meth)acrylamide include the following examples which are not meant to be limiting on this invention: copolymers of (meth)acrylamide with dimethylaminoethyl methacrylate (DMAEM), dimethylaminoethyl acrylate (DMAEA), diethylaminoethyl acrylate (DEAEA), diethylaminoethyl methacrylate (DEAEM) or their quaternary ammonium forms made 15 with dimethyl sulfate or methyl chloride, Mannich reaction modified polyacrylamides, diallylcyclohexylamine hydrochloride (DACHA HCl), diallyldimethylammonium chloride (DADMAC), methacrylamidopropyltrimethylammonium chloride (MAPTAC) and allyl amine (ALA).
The high molecular weight anionic polymers are preferably water-soluble vinyl 20 copolymers of (meth)acrylamide with following monomers: acrylic acid, 2-acrylamido-2-methylpropane sulfonate (AMPS) and mixture thereof. The anionic high molecular weight (co)polymers may also be either hydrolyzed acrylamide polymers or copolymers of acrylamide or its homologues, such as methacrylamide, with acrylic acid or its CA 0220~277 1997-0~-13 homologues, such as methacrylic acid, or with monomers, such as maleic acid, itaconic acid, vinyl sulfonic acid, AMPS, or other sulfonate Cont~inin~ monomers.
he anionic polymers may be sulfonate or phosphonate co"~i-i"i"g polymers which have been synthesized by modifying acrylamide polymers in such a way as to obtain 5 sulfonate or phosphonate substitutions, or mixtures thereof. The most preferred high molecular weight anionic retention polymers are acrylic acid/acrylamide copolymers, and sulfonate cont~ining polymers such as 2-acrylamide-2-methylpropane sulfonate/acrylamide copolymer (AMPS), acrylamido methane sulfonate acrylamide (AMS), acrylamido ethane sulfonate/acrylamide (AES) and 2-hydroxy-3-acrylamide 10 propane sulfonate/acrylamide (HAPS).
It is preferred that nonionic, cationic and anionic polymers have a molecular weight of at least about 500,000 to about 30,000,000. A more preferred molecular weight is at least about 1,000,000 to about 30,000,000 with the best results observed when molecular weight is between about 5,000,000 to about 30,000,000. The anionic or 15 cationic monomer may constitute up to about 80 mole % of the copolymer, with best results observed the range of about 0 to about 30 mole % of an anionic or a cationic charge.
The invention can be used in the presence of any effective flocculation program applied in the mill. In a single polymer program, a flocculant, typically a cationic 20 polymer, is the only material added. Another method of improving the flocculation of cellulosic fines, mineral fillers and other furnish components on the fiber mat is the dual polymer program, also referred to as a coagulant/flocculant system, added ahead of the paper machine.
CA 0220~277 1997-0~-13 In such a system there is first added a coagulant, for instance a low molecular weight synthetic cationic polymer or cationic starch to the furnish, which coagulant generally reduces the negative surface charges present on the particles in the furnish, partlcularly cellulosic fines and mineral fillers, and thereby accomplishes a degree of 5 agglomeration of such particles, followed by the addition of a flocculant. Such flocculant 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 10 the fiber web, whereas unagglomerated particles would to a great extent pass through such paper web.
Coagulant is typically a cationic polymer having a low molecular weight of at least about 1,000 and less than about 500,000. More preferably, the molecular weights range from about 2,000 to about 200,000.
Examples of polymers used as coagulants include copolymers of diallyldimethylammonium chloride and monomers selected from the group consisting of quaternized dimethylaminoethylacryaltes, quaternized dimethylaminomethacrylates, vinyltrimethoxysilane, acrylamide, diallyldimethylaminoalkyl(meth)acrylate, diallyldimethylaminoalkyl(meth)acrylamide and mixtures thereof. In addition, polymers 20 that can be used include polyethylene imines, polyamines, polycyandiamide formaldehydes, diallyldimethylammonium chlorides, diallyldimethylaminoalkyl(meth)acrylates, diallyldimethylaminoalkyl(meth)acrylamides, polymethylamine epichlorohydrins as well as co-polymers of acrylamide and/or CA 0220~277 1997-0~-13 diallyldimethylaminoalkyl(meth)acrylates and diallyldimethylaminoalkyl(meth)acrylamides or co-polymers of ammonium ethylene dichorides or acrylamido N,N-dimethyl piper~7ine q~ e",~,~y acrylamides.
Polymers applicable to this invention may also include vinylamine polymers 5 cont~ining at least one monomer selected from the group consisting of arnidine vinylformamide, vinyl alcohol, vinyl acetate, vinyl pyrrolidinone and the esters, amides, nitriles and salts of acrylic acid and methacrylic acid.
Paper or paper board is generally made from a suspension or slurry of cellulosic material in an aqueous medium, which slurry is subjected to one or more shear stages, in 10 which such stages generally are a cleaning stage, a mixing stage and a pumping stagè, and thereafter the suspension is drained to form a sheet, which sheet is then dried to the desired, and generally low, water concentration.
Microparticle retention programs are based on the effect of restoration of the originally formed flocs which are then sheared. In such applications, the flocculant is 15 added before at least one high shear point, followed by the addition of microparticle just before the headbox. Typically, a flocculant will be added before the pressure screens, followed by the addition of microparticle after the screens. Secondary flocs formed by the addition of microparticles result in increased retention and drainage without detrimentally affecting formation of the sheet. This allows increased filler content in the 20 sheet. elimin~tes two-sidedness of the sheet, and increases drainage and speed of the machine in paper manufacturing. A number of substances are used as microparticles, but the best known are bentonite and colloidal silica.
CA 0220~277 1997-0~-13 The use of the excess amount of polymeric flocculant or coagulant is believed necessary to ensure that the subsequent shearing results in the formation of microflocs which contain or carry sufficient polymer to render at least parts of their surfaces positively charged, although it is not necessary to render the whole slurry positively 5 charged. Thus the Zeta potential of the slurry, after the addition of the acrylamide copolymer and after the shear stage, may be cationic or anionic.
Shear may be provided by a device in the a~u~dLus used for other purposes, such as a mixing pump, fan pump or centriscreen, or one may insert into the a~paldlus a shear mixer or other shear stage for the purpose of providing shear, and preferably a high 10 degree of shear subsequent to the addition of the copolymer.
Another embodiment of the invention is a method for minimi7ing pitch, ink, and stickie particle deposits in the paper making process by causing retention of such particles onto fiber comprising the steps of:
a) adding to a suspension in contact with a paper machine and associated parts from about 0.005 to about 0.5 % by weight based on fiber in suspension of a flocculant:
b) subjecting the suspension to at least one shear stage; and c) adding to the suspension from about 0.005 to about 0.5 % by weight based on fiber in suspension of a mi~;ture of bentonite and talc, ~0 thereby increasing retention of pitch~ ink. and stickies onto the fiber and minimi7ing the deposition of pitch, ink, and stickies particles on the paper machine and associated parts.
The suspension may be selected from the group consisting of fine paper, board, CA 0220Ct277 1997 0Ct- 13 and grades made from mechanical pulps. The flocculant may be selected from the group consisting of cationic, nonionic, and anionic polymeric flocculants.
In one embodiment of the invention, the talc may be added to the suspension before the bentonite is added to the suspension. In an alternative embodiment of the 5 invention, the talc and the bentonite may be added simultaneously or as a mixture to the suspension in contact with the paper machine and associated parts.
The ratio of the talc to the bentonite is p-er~l-dbly from about 0.1 to about 5.
From about 0.05 to about 20 kilograms of the talc per ton of fiber in suspension may be added to the suspension in contact with the paper machine and associated parts. In addition, from about 0.05 to about 10 kilograms of the bentonite per ton of fiber in suspension may be added to the suspension in contact with the paper machine and associated parts.
Mixtures of bentonite and talc provide several advantages. Retention is enhanced when the combination of talc/bentonite is used. Residual, unretained, pitch in the systen 15 is also less sticky (detackified) and therefore, exhibits lower propensity for deposition.
Any deposits that may be formed tend to be less sticky and can be more easily removed.
Feeding bentonite and talc as a mixture allows for a more controlled dosage. Brightness resulting from the combination is higher than the brightness obtained with bentonite alone. Talc is known to cause a slippery sheet at higher dosages, resulting in press room 20 runnability problems. By using a mixture of talc and bentonite, the talc dosage can be reduced, thereby, reducing the problems at the winding stage with crepe wrinkles and fewer problems in the printing press rooms from slippery paper.
CA 0220~277 1997-0~-13 In addition, use of the talc/bentonite mixture as a microparticle where the mixture is fed after the use of a high molecular weight polymer provides improvement in formation as well as retention.
BENTûNi 1 E AND TALC T~ATMENT LEVELS
The amounts of bentonite and talc which has been found effective ranges from a concentration of approximately 0.05 kilograms of bentonite and 0.05 kilograms of talc per ton of pulp solids up to and including about 10 kilograms of bentonite and 20 kilograms of talc per ton of pulp solids.
Preferably, treatment levels range between about 0.1 kilograms of bentonite and 0.5 kilograms of talc per ton total pulp solids to about 5 kilograms of bentonite and 10 kilograms of talc per ton of pulp solids. Most preferably, the effective treatment ranges are between about 0.5 kilograms of bentonite and 1 kilogram of talc per ton of pulp solids to about 3 kilograms of bentonite and 5 kilograms of talc per ton of pulp solids, although each source of newsprint pulp can and does have its own character and the treatment level demand. In cases where talc is also added to the system as a filler, the dosages of talc may be higher than the dosages given here.
EVALUATION OF THE INVENTIûN
~0 The following examples are presented to describe pl~felled embodiments and utilities of the invention and are not meant to limit the invention unless otherwise stated in the claims appended hereto.
CA 0220~277 1997-0~-13 Lxample To test the amount of pitch, ink, and stickies particle deposition in paper making systems treated with the compositions of the instant invention, a coupon test was employed. A 500 ml sample of dry lap kraft pulp from the mill is obtained. 100 ml of a 1% synthetic pitch solution in isopropanol is added to the pulp sample. The sample is stirred with a spatula and the pH is adjusted to 6.2 - 6.3 with concentrated HCl. The pulp mixture is then stirred in a blender. S ml of an 0.5 M CaC12 2 H2O solution is added to the stirred pulp mixture. Treating agents to be evaluated are added next. A pre-weighed Teflon coupon is suspended in the stirred pulp mixture. After a pre-determined length of time, the coupon is removed and rinsed with water. The coupon is oven dried, andsubsequently weighed to determine the amount of deposition. A decrease in percent deposition above the value obtained for the blank experiment indicates that the treatment inhibits deposition.
1 i TABLE 1 dosage % %
treatment (kg/ton)DepositionImprovement related to blank talc 3 30.7 - 58 bentonite/talc 3 4.1 65 bentonite/talc/ 3/3/1 1.5 87 treatment polymer polymeric 0.513131 2.1 82 coagulant/bentonite /talc/treatrnent polymer , ' CA 0220~277 1997-0~-13 As can be seen in Table I, talc added alone at a low dosage increases the amount of deposition. In combination with other component programs, low dosages of talc result in decrease of deposition. Such programs provided improved control of residual unretained pitch and the talc was less tacky and less prone to deposition on the different 5 elements of the paper machine. In addition, the combination of bentonite and talc provide a wider spectrum of applications as bentonite and talc each have an affinity to a different fraction of pitch and stickies particles. Polymer used in this example is the dadmac-polyacrylamide copolymer with RSV=6 and charge density of lmEq/g.
Changes can be made in the composition, operation and arrangement of the 10 method of the present invention described herein without departing from the concept and scope of the invention as defmed in the following claims:
A method for minimi~ing pitch, ink, and stickies particle deposition in the paper making process compri~ing the steps of adding an effective pitch, ink, and stickies controlling amount of talc and bentonite to the fiber suspension and adding an effective pitch, ink, and siickies controiiing amount of bentonite to the suspension, thereby reducing the pitch, ink, and stickies particle deposition in the paper making process.
BACKGROUND OF THE INVE~TION
The problem of pitch, ink, stickies particle deposition control in the paper making 10 process for all types of paper has previously been recognized. The pitch in the fibers of wood pulps is associated with naturally occurring lignin dispersing agents. Cooking and mechanical agitation which occur during the pulping by the sulfate process liberate pitch and these natural dispersing agents. However, as a result of the mechanical work on the fibers~ the natural dispersing agents liberated along with the pitch are inadequate to keep 15 the pitch from depositing on the equipment employed in beating, hydrating, refining, bleaching~ and even on the wire used for forming the sheet.
Because of the tendency of the pitch to agglomerate within the pulp suspension or deposii on ihe surfaces of the wire or other equipment, the pitch frequently causes the formation of spots or holes in the sheet formed. Additionally, the pitch may adhere to the 20 wire or press rolls or dryer rolls and cause tearing of the sheet. The result of the pitch cont~min~tion is the production of sheets with numerous imperfections. Among other consequences of pitch particle deposition are the expense of cleaning the m~c.hinery CA 0220~277 1997-0~-13 frequently either with solvents or steam, and the loss of produetion during cleaning and replaeing operations eaused by breakdown of the sheet.
Organie eont~min~nts, sueh as ink and adhesives whieh are present in recycled paper, can have a sticky or tacky nature. The problems of h~nrlling such eont~min~nts, 5 referred to as ink and stiekies, is similar to the problems eneountered with pitch.
Water soluble polymers, and in particular, cationie water soluble polymers, have been used in the production of paper for a number of purposes. Water soluble polymers have been added to pulps to improve fine and filler retention. In another instance, these polymers have been used to improve drainage of water from the pulp as it is formed into 10 a sheet on wires or felts. Polymers have also been used to attaeh piteh particles to cellulose fibers while they were in a colloidal state thereby preventing them from agglomerating and accumulating on the surfaces of production equipment. Polymers also have been used for improved efficiency in retaining fillers, such as clays.
In the case of cationic polymeric coagulants, it is necessary to combine them with i S flocculants to make their performance acceptable. Examples of cationic polymers used for pitch retention, see (~n~ n Patent Applications, 1,150,914 and 1,194,254, the disclosures of which are incorporated herein by reference. These applications disclose cationic polymers which give superior colloidal pitch particle reduction in aqueous pulps such as polyquaternary polymers of essentially linear structure consisting of essentially of 20 a difunctional reaction product of a lower dialkylamine and a difunctional epoxy compound selected from the group consisting of epihalohydrins, diepoxide, precurors of epihalohydrins and diepoxides. and poly-diallyldimethyl ammonium chloride, CA 0220~277 1997-0~-13 respectively. See also U.S. Patent No. 5,098,520 and allowed U.S. Patent Application No. 08/148,069, the disclosure of which is incorporated herein by reference.
Previous products used for this purpose have included low molecular weight polymers of DADMAC, epichlorohydrin ~ mine polymers or other polyamines 5 including polyethyleneimine. Due to the low molecular weight, these products were often less effective as retention aids and in some cases had to be supplemented with a high molecular weight flocculant to achieve their desired level of retention. Flocculants by themselves failed to give adequate retention of colloidal m~tçri~l~, often hurting machine runability.
The paper making process, particularly the production of newsprint, presents a challenge to the paper maker with respect to optimi7ing production. It is increasingly common to use recycled fiber rather than virgin fiber in n~w~lhlt furnish. Due to the nature of newsprint and the necessity to carefully control costs, problems such as retention, drainage and pitch, ink, and stickies particle deposition control must be solved 15 economically. It would represent an advance in the art if newsprint mills, as well as other paper mills, could use one product which could solve or improve the several problems described above.
In recent years, the use of retention programs using inorganic "microparticles" has gained acceptance. Microparticle programs are defined not only by the use of a 20 microparticle component but also by the addition points of chemicals in relation to shear.
In order to be effective, conventional retention and drainage programs require incorporation of some higher molecular weight component as part of the program. In conventional programs, the high molecular weight component is added after a high shear CA 0220~277 1997-0~-13 point in the stock flow system leading up to the headbox of the paper m~chine. Flocs that are forrned by addition of the high molecular weight component are broken down to some extent by the high shear. Since these flocs are formed primarily by the bridging mech~ni~m, this breakdown is largely irreversible and flocs do not re-form to any 5 significant extent. For this reason, most of the retention and drainage performance of the flocculant is lost by feeding it before a high shear point. Additionally, a need for feeding the high molecular weight polymer after the high shear point often leads to formation problems. The feeding requirements of the high molecular weight polymers and copolymers which provides improved retention often leads to a col.lplolllise in formation.
In the microparticle retention programs, high molecular weight polymer is added before at least one high shear point. An inorganic, particulate material is then added to the furnish after the stock has been flocculated with the high molecular weight component and subjected to shear. The microparticle, usually highly negatively charged, is added to a furnish pretreated with some cationic material [e.g., starch, coagulant, alum, cationic flocculant] so that the primary mechanism of operation appears to be an electrostatic interaction. The microparticle addition re-flocculates the furnish, resulting in retention and drainage that is at least as good as that attained using the high molecular wei~ht component in the conventional way (after shear), with no deterious impact on formation .
One such program employed to provide an improved combination of retention and dewatering is described in United States Pat. Nos. 4,753,710 and 4,913,775, inventors Langley et al.. issued respectively June 28, 1988 and April 3, 1990, incorporated hereunto by ref'erence. In the disclosed method. a high molecular weight linear cationic polymer is CA 0220~277 1997-0~-13 added to the aqueous cellulosic paper making suspension before shear is applied to the suspension, followed by the addition of bentonite after the shear application. Shearing is generally provided by one or more of the cleaning, mixing and pumping stages of the paper making process, and the shearing breaks down the large flocs formed by the high 5 molecular weight polymer into microflocs, and further agglomeration then ensues with the addition of the bentonite clay particles.
The treatment of an aqueous cellulosic slurry with a high molecular weight cationic polymer followed by shear, preferably a high degree of shear, is a wet-end treatment in itself known in the field, for instance as described in aforesaid United States Pat. Nos. 4,753,710 and 4,913,775, inventor Langley et al., issued respectively June 28, 1988, and April 3, 1990, incorporated herein by reference.
Other such programs are based on the use of colloidal silica as a microparticle in combination with cationic starch (Sunden et al., U. S. Pat. No. 4,388,150 issued on June 14, 1983) known as Composil (Eka Nobel) or cationic starch and flocculant combination (Johnson, U.S. Pat. No. 4,643,801 issued on February 17, 1987) and known as Positek (Nalco). Since the onset of the microparticle-based technology, a number of other, synthetic organic microparticles have been developed and introduced to the market.
Talc and bentonite are widely used in the paper industry. Talc is primarily used as a pitch control agent and more recently for stickies control in recycled fibre. Bentonite is 20 often used as part of a retention program. Using the two components together in dry form or as a slurry prior to delivery to the mill offers several advantages from both a perforrnance and a handling points of view.
CA 0220~277 1997-0~-13 The present invention is predicated upon the discover.v that talc used in combination with bentonite is capable of improving pitch, ink, and stickies particle retention to the fiber, thereby minimi7in~ the deposition of pitch, ink, and stickies particles on the surfaces of the paper m~chine and associated parts (structures) which include, felts, pipes, wires, pumps, tanks, and the like in the production of all types of paper.
SUMMARY OF THE INVENTION
The invention is a method for minimi7inp; pitch, ink, and stickies deposition in the 10 paper making process by causing the retention of such particles onto fiber, comprising the steps of adding an effective pitch, ink, and stickies controlling amount of taic to a suspension of fiber in contact with the paper machine and associated parts and adding an effective pitch, ink, and stickies controlling amount of bentonite to the suspension in contact with the paper machine and associated parts, thereby increasing retention of pitch, 15 inl;, and stickies onto the fiber and minimi7.ing pitch, ink, and stickies particles deposition on the paper machine and associated parts.
The bentonite and talc may be added to the separately to the paper making suspension in any order of addition. Additionaiiy, the bentonite and the taic may aiso be added simultaneously to the suspension in contact with the paper machine and associated 20 parts. The ratio of bentonite to talc is preferably from about 1:1 to about 0.1:20, more preferably from about 1:1 to 0.1:10, and most preferably from about 1:1 to 1:5.
, ' CA 0220~277 1997-0~-13 DESCRIPTION OF THE INVENTION
The invention comprises a method for improving the paper making process, particularly the production of n~w~l lh~t, filled n~w~,hl~, coated paper, all grades cont~ining mechanical pulp, board paper, by improving the pitch and stickies control in 5 the pulp and paper making process. The pitch, ink, stickies formation and deposits are minimize~l and in some cases elimin~terl Specifically, it comprises adding an effective pitch, ink, and stickies controlling amount of bentonite having a high swelling capacity in water to a suspension of fiber in contact with the paper m~hine and associated parts, and then, an effective pitch, ink, and stickies controlling amount of talc is also added to the 10 suspension in contact with the paper machine and associated parts, thereby increasing retention of pitch, ink, and stickies onto the fiber and minimi7inp the deposition of pitch, ink, and stickies particles on the paper machine and associated parts.
Bentonite is a colloidal clay, commercially available, composed predomin:~ntly of montmorillonite. The Wyoming or Western variety of bentonite is a sodium bentonite 15 which has a high water swelling capacity. The Southern variety is a calciurn bentonite with negligible swelling capacity. The bentonite can be any of the materials commercially referred to as bentonites or bentonite-type clays. Preferably, the bentonite is of the type having a high swelling capacity in water, such as sodium potassiurn bentonite. Bentonite clay has the desirable property of being thixo-tropic and shear 20 thinning, i.e.. it forms a network which is easily destroyed by the application of shear, but then reforms when shear is removed.
The dry particle size of the bentonite is preferably at least 90 % below 100 microns and most preferably at least 60 % below 50 microns. The surface area of the CA 0220~277 1997-0~-13 bentonite partieles before swelling is preferably at least 30 and more preferably at least 50, and most preferably between 60 to 90 m2/gm. The surface area after swelling is preferably between 400 and 800 m2/gm. The ~,cr~l,cd type of the bentonite swells at least 15 or 20 times. The partiele size after swelling is preferably at least 90 % below 2 5 mierons.
Tale, an inexpensive material, commercially available, which is commonly used for pitch, ink and stickies deposition control in pulp and paper mills, is a crystalline powder of a natural hydrous m~gnesium silicate. The crystallographic structure of talc results in a platelet-like appearance. The edges of these platelets are hydrophilic, and as 10 such is responsible for the dispersability of talc in water. The hydrophobic faces of the platelets are able to interact with hydrophobic substances, such as pitch and stickies particles.
Colloidal pitch adsorbs onto the hydrophobic faces of the talc crystal, thereby preventing the formation of large pitch agglomerates. "Detackification", a ch~nging of 15 the surface properties of pitch and stickies particles, is recognized as the operating mechanism of talc. The talc/pitch particles are retained in the fiber mat as its forms, thereby preventing the recirculation, concentration and eventual deposition of these particles in the system.
However, the exposure of the talc/pitch agglomerate to shear will often create a 20 fresh, sticky surface which can cause deposit problems further on in the paper m~kin~
process. Other disadvantages to using talc include the high talc dosage rates often required to give good pitch, ink, and stickies deposition control and its abrasiveness which decreases the useful life of paper machine components such as wires, pick-up rolls CA 0220~277 1997-0~-13 and felts. At the high dosages of talc, a very effective retention program must be in place or wire and felt plugging in the press section of a paper m~hine will occur. However, high dosages of talc can also increase the slipperiness of the sheet formed, resulting in problems during the process of winding and in the printing presses. At low dosages of S talc, the deposition of pitch and stickies particles possible as well as the talc itself becoming a part of the deposit thereby increasing the mass of deposit formed during the paper making process.
The use of talc in combination with bentonite (or b~ onile and a treatment polymer used to improve the retention capacity in a furnish) allows a reduction in the 10 dosage of talc while producing an effective pitch and stickies control program and avoiding the disadvantages of high talc dosage rates such as felt plugging and slipperiness problems. Bentonite increases the retention of talc particles. Complete retention of pitch and stickies particles in the formed web of paper is most likely not possible. Therefore, the addition of a small amount of talc in combination with bentonite or a 15 bentonite/treatment polymer program will allow detackification of the rem~ining unretained pitch particles.
The term "paper machine", as used herein, includes felts, pumps, wires, tanks, pipes and similar associated parts as well as all metal surfaces where the fiber suspension contacts the surface of the paper machine. The term "suspension" as used herein includes 20 pulp, fiber suspended in water, furnishes and the like.
The talc may be added to the suspension before the bentonite is added to the suspension. In another embodiment, the bentonite and the talc may be added simultaneously to the suspension in contact with the paper machine and associated parts.
-CA 0220~277 1997-0~-13 In addition, the bentonite and talc may be added as a mixture. The bentonite and talc can be mixed together in the powdered form. This may be done on-site, but likely off-site at the point where one or the other is mined or manufactured. Bentonite and talc have similar requlrements for pLe~alillg a slurry of either in terms of mixing. Preparing a 5 slurry of the mixture will therefore require less equipment and also make feeding and metering easier, making the invention easier to practice.
The ratio of bentonite to talc is preferably from about 1:1 to 0.1:20, more preferably from 1:1 to 0.1:10, and most preferably from about 1:1 to 1:5.
The talc/bentonite treatment program may be added to paper making systems to 10 improve pitch, ink, and stickies control. This talclbentonite tre~tment program is also effective in treating newsprint made from either virgin or recycled fibers. It is understood that the term, "newsprint" as used herein includes other grades of paper which contain mechanical pulp~ recycled or deinked pulp.
The talc and bentonite are added to the pulp slurry (suspension). Both bentonite 15 and talc. added separately or as a mixture, can be fed at any point to the paper making process or suspension, at any point in the paper machine. In addition, the bentonite and talc. added separately or as a mixture. can be added as a dry powder or as a hydrated suspension obtained by dispersing powdered material in water.
Since both bentonite and talc require hydration prior to injection into the paper 20 mal;ing system. delivering them to the site as a mixture and hydrating the mixture in the same tanli is advantageous in reducing the amount of mechanical equipment required to perforrm the hydration.
CA 0220~277 1997-0~-13 Dosages of Bentonite and Talc Bentonite Talc 0.05 - 10 0.05 - 20 0.1 - 5 0.5 - 10 0.5-3 1-5 The invention can be used in the presence of any effective retention program applied in the mill. An effective retention program is required to provide retention of 10 talc, which if unretained could cause felt plugging problem. It would be preferable to use the invention in the presence of a retention program wherein the retention of the talc would be benefited. A wide variety of chemistries are known in the art to work as retention agents, including polymeric materials. Examples of the polymeric material that can be used as a retention program include acrylamide homopolymers, copolymers, 15 terpolymers, and so on.
The polymers useful in the practicing of this invention contain at least one of the monomers chosen from the group consisting of acrylamide, methacrylamide, N-tertiary butyl acrylamide, 2-acrylamido-2-methylpropane sulfonate, sulfomethyl acrylamide, sulfomethyl methacrylamide~ sulfoethylacrylamide, and the like. In addition, the 20 polymeric retention material may also be the difunctional reaction product of a lower dialkylamine and a difunctional epoxy compound selected from the group consisting of epihalohydrins, diepoxide, precurors of epihalohydrins and diepoxides, as well as poly-diallyldimethyl ammonium chloride.
CA 0220~277 1997-0~-13 The polymers used in the application of this invention are generally selected from, however, not limited to, following examples. These polymers belong to one of the three classes: nonionic, anionic and cationic. The nonionic polymers are homopolymers or copolymers of nonionic monomers. The plef~.,ed nonionic monomer is acrylamide or 5 methacrylamide and pler~lled nonionic polymers are polyacrylamide and polymethacrylamide.
By the term of cationic retention polymers, it is understood to include any water-soluble copolymer of (meth)acrylamide which carries or is capable of carrying the cationic charge when dissolved in water, whether or not this charge-carrying capacity is 10 dependent upon pH. The cationic copolymers of (meth)acrylamide include the following examples which are not meant to be limiting on this invention: copolymers of (meth)acrylamide with dimethylaminoethyl methacrylate (DMAEM), dimethylaminoethyl acrylate (DMAEA), diethylaminoethyl acrylate (DEAEA), diethylaminoethyl methacrylate (DEAEM) or their quaternary ammonium forms made 15 with dimethyl sulfate or methyl chloride, Mannich reaction modified polyacrylamides, diallylcyclohexylamine hydrochloride (DACHA HCl), diallyldimethylammonium chloride (DADMAC), methacrylamidopropyltrimethylammonium chloride (MAPTAC) and allyl amine (ALA).
The high molecular weight anionic polymers are preferably water-soluble vinyl 20 copolymers of (meth)acrylamide with following monomers: acrylic acid, 2-acrylamido-2-methylpropane sulfonate (AMPS) and mixture thereof. The anionic high molecular weight (co)polymers may also be either hydrolyzed acrylamide polymers or copolymers of acrylamide or its homologues, such as methacrylamide, with acrylic acid or its CA 0220~277 1997-0~-13 homologues, such as methacrylic acid, or with monomers, such as maleic acid, itaconic acid, vinyl sulfonic acid, AMPS, or other sulfonate Cont~inin~ monomers.
he anionic polymers may be sulfonate or phosphonate co"~i-i"i"g polymers which have been synthesized by modifying acrylamide polymers in such a way as to obtain 5 sulfonate or phosphonate substitutions, or mixtures thereof. The most preferred high molecular weight anionic retention polymers are acrylic acid/acrylamide copolymers, and sulfonate cont~ining polymers such as 2-acrylamide-2-methylpropane sulfonate/acrylamide copolymer (AMPS), acrylamido methane sulfonate acrylamide (AMS), acrylamido ethane sulfonate/acrylamide (AES) and 2-hydroxy-3-acrylamide 10 propane sulfonate/acrylamide (HAPS).
It is preferred that nonionic, cationic and anionic polymers have a molecular weight of at least about 500,000 to about 30,000,000. A more preferred molecular weight is at least about 1,000,000 to about 30,000,000 with the best results observed when molecular weight is between about 5,000,000 to about 30,000,000. The anionic or 15 cationic monomer may constitute up to about 80 mole % of the copolymer, with best results observed the range of about 0 to about 30 mole % of an anionic or a cationic charge.
The invention can be used in the presence of any effective flocculation program applied in the mill. In a single polymer program, a flocculant, typically a cationic 20 polymer, is the only material added. Another method of improving the flocculation of cellulosic fines, mineral fillers and other furnish components on the fiber mat is the dual polymer program, also referred to as a coagulant/flocculant system, added ahead of the paper machine.
CA 0220~277 1997-0~-13 In such a system there is first added a coagulant, for instance a low molecular weight synthetic cationic polymer or cationic starch to the furnish, which coagulant generally reduces the negative surface charges present on the particles in the furnish, partlcularly cellulosic fines and mineral fillers, and thereby accomplishes a degree of 5 agglomeration of such particles, followed by the addition of a flocculant. Such flocculant 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 10 the fiber web, whereas unagglomerated particles would to a great extent pass through such paper web.
Coagulant is typically a cationic polymer having a low molecular weight of at least about 1,000 and less than about 500,000. More preferably, the molecular weights range from about 2,000 to about 200,000.
Examples of polymers used as coagulants include copolymers of diallyldimethylammonium chloride and monomers selected from the group consisting of quaternized dimethylaminoethylacryaltes, quaternized dimethylaminomethacrylates, vinyltrimethoxysilane, acrylamide, diallyldimethylaminoalkyl(meth)acrylate, diallyldimethylaminoalkyl(meth)acrylamide and mixtures thereof. In addition, polymers 20 that can be used include polyethylene imines, polyamines, polycyandiamide formaldehydes, diallyldimethylammonium chlorides, diallyldimethylaminoalkyl(meth)acrylates, diallyldimethylaminoalkyl(meth)acrylamides, polymethylamine epichlorohydrins as well as co-polymers of acrylamide and/or CA 0220~277 1997-0~-13 diallyldimethylaminoalkyl(meth)acrylates and diallyldimethylaminoalkyl(meth)acrylamides or co-polymers of ammonium ethylene dichorides or acrylamido N,N-dimethyl piper~7ine q~ e",~,~y acrylamides.
Polymers applicable to this invention may also include vinylamine polymers 5 cont~ining at least one monomer selected from the group consisting of arnidine vinylformamide, vinyl alcohol, vinyl acetate, vinyl pyrrolidinone and the esters, amides, nitriles and salts of acrylic acid and methacrylic acid.
Paper or paper board is generally made from a suspension or slurry of cellulosic material in an aqueous medium, which slurry is subjected to one or more shear stages, in 10 which such stages generally are a cleaning stage, a mixing stage and a pumping stagè, and thereafter the suspension is drained to form a sheet, which sheet is then dried to the desired, and generally low, water concentration.
Microparticle retention programs are based on the effect of restoration of the originally formed flocs which are then sheared. In such applications, the flocculant is 15 added before at least one high shear point, followed by the addition of microparticle just before the headbox. Typically, a flocculant will be added before the pressure screens, followed by the addition of microparticle after the screens. Secondary flocs formed by the addition of microparticles result in increased retention and drainage without detrimentally affecting formation of the sheet. This allows increased filler content in the 20 sheet. elimin~tes two-sidedness of the sheet, and increases drainage and speed of the machine in paper manufacturing. A number of substances are used as microparticles, but the best known are bentonite and colloidal silica.
CA 0220~277 1997-0~-13 The use of the excess amount of polymeric flocculant or coagulant is believed necessary to ensure that the subsequent shearing results in the formation of microflocs which contain or carry sufficient polymer to render at least parts of their surfaces positively charged, although it is not necessary to render the whole slurry positively 5 charged. Thus the Zeta potential of the slurry, after the addition of the acrylamide copolymer and after the shear stage, may be cationic or anionic.
Shear may be provided by a device in the a~u~dLus used for other purposes, such as a mixing pump, fan pump or centriscreen, or one may insert into the a~paldlus a shear mixer or other shear stage for the purpose of providing shear, and preferably a high 10 degree of shear subsequent to the addition of the copolymer.
Another embodiment of the invention is a method for minimi7ing pitch, ink, and stickie particle deposits in the paper making process by causing retention of such particles onto fiber comprising the steps of:
a) adding to a suspension in contact with a paper machine and associated parts from about 0.005 to about 0.5 % by weight based on fiber in suspension of a flocculant:
b) subjecting the suspension to at least one shear stage; and c) adding to the suspension from about 0.005 to about 0.5 % by weight based on fiber in suspension of a mi~;ture of bentonite and talc, ~0 thereby increasing retention of pitch~ ink. and stickies onto the fiber and minimi7ing the deposition of pitch, ink, and stickies particles on the paper machine and associated parts.
The suspension may be selected from the group consisting of fine paper, board, CA 0220Ct277 1997 0Ct- 13 and grades made from mechanical pulps. The flocculant may be selected from the group consisting of cationic, nonionic, and anionic polymeric flocculants.
In one embodiment of the invention, the talc may be added to the suspension before the bentonite is added to the suspension. In an alternative embodiment of the 5 invention, the talc and the bentonite may be added simultaneously or as a mixture to the suspension in contact with the paper machine and associated parts.
The ratio of the talc to the bentonite is p-er~l-dbly from about 0.1 to about 5.
From about 0.05 to about 20 kilograms of the talc per ton of fiber in suspension may be added to the suspension in contact with the paper machine and associated parts. In addition, from about 0.05 to about 10 kilograms of the bentonite per ton of fiber in suspension may be added to the suspension in contact with the paper machine and associated parts.
Mixtures of bentonite and talc provide several advantages. Retention is enhanced when the combination of talc/bentonite is used. Residual, unretained, pitch in the systen 15 is also less sticky (detackified) and therefore, exhibits lower propensity for deposition.
Any deposits that may be formed tend to be less sticky and can be more easily removed.
Feeding bentonite and talc as a mixture allows for a more controlled dosage. Brightness resulting from the combination is higher than the brightness obtained with bentonite alone. Talc is known to cause a slippery sheet at higher dosages, resulting in press room 20 runnability problems. By using a mixture of talc and bentonite, the talc dosage can be reduced, thereby, reducing the problems at the winding stage with crepe wrinkles and fewer problems in the printing press rooms from slippery paper.
CA 0220~277 1997-0~-13 In addition, use of the talc/bentonite mixture as a microparticle where the mixture is fed after the use of a high molecular weight polymer provides improvement in formation as well as retention.
BENTûNi 1 E AND TALC T~ATMENT LEVELS
The amounts of bentonite and talc which has been found effective ranges from a concentration of approximately 0.05 kilograms of bentonite and 0.05 kilograms of talc per ton of pulp solids up to and including about 10 kilograms of bentonite and 20 kilograms of talc per ton of pulp solids.
Preferably, treatment levels range between about 0.1 kilograms of bentonite and 0.5 kilograms of talc per ton total pulp solids to about 5 kilograms of bentonite and 10 kilograms of talc per ton of pulp solids. Most preferably, the effective treatment ranges are between about 0.5 kilograms of bentonite and 1 kilogram of talc per ton of pulp solids to about 3 kilograms of bentonite and 5 kilograms of talc per ton of pulp solids, although each source of newsprint pulp can and does have its own character and the treatment level demand. In cases where talc is also added to the system as a filler, the dosages of talc may be higher than the dosages given here.
EVALUATION OF THE INVENTIûN
~0 The following examples are presented to describe pl~felled embodiments and utilities of the invention and are not meant to limit the invention unless otherwise stated in the claims appended hereto.
CA 0220~277 1997-0~-13 Lxample To test the amount of pitch, ink, and stickies particle deposition in paper making systems treated with the compositions of the instant invention, a coupon test was employed. A 500 ml sample of dry lap kraft pulp from the mill is obtained. 100 ml of a 1% synthetic pitch solution in isopropanol is added to the pulp sample. The sample is stirred with a spatula and the pH is adjusted to 6.2 - 6.3 with concentrated HCl. The pulp mixture is then stirred in a blender. S ml of an 0.5 M CaC12 2 H2O solution is added to the stirred pulp mixture. Treating agents to be evaluated are added next. A pre-weighed Teflon coupon is suspended in the stirred pulp mixture. After a pre-determined length of time, the coupon is removed and rinsed with water. The coupon is oven dried, andsubsequently weighed to determine the amount of deposition. A decrease in percent deposition above the value obtained for the blank experiment indicates that the treatment inhibits deposition.
1 i TABLE 1 dosage % %
treatment (kg/ton)DepositionImprovement related to blank talc 3 30.7 - 58 bentonite/talc 3 4.1 65 bentonite/talc/ 3/3/1 1.5 87 treatment polymer polymeric 0.513131 2.1 82 coagulant/bentonite /talc/treatrnent polymer , ' CA 0220~277 1997-0~-13 As can be seen in Table I, talc added alone at a low dosage increases the amount of deposition. In combination with other component programs, low dosages of talc result in decrease of deposition. Such programs provided improved control of residual unretained pitch and the talc was less tacky and less prone to deposition on the different 5 elements of the paper machine. In addition, the combination of bentonite and talc provide a wider spectrum of applications as bentonite and talc each have an affinity to a different fraction of pitch and stickies particles. Polymer used in this example is the dadmac-polyacrylamide copolymer with RSV=6 and charge density of lmEq/g.
Changes can be made in the composition, operation and arrangement of the 10 method of the present invention described herein without departing from the concept and scope of the invention as defmed in the following claims:
Claims (25)
1. A method for minimizing pitch, ink, and stickies particle deposits in a paper making process by causing the retention of such particles onto fiber, comprising the steps of:
a) adding an effective pitch, ink, and stickies controlling amount of bentonite having a high swelling capacity in water to a suspension of fiber in contact with the paper machine or an associated part thereof; and b) adding an effective amount of talc to the suspension in contact with the paper machine or an associated part thereof, thereby increasing retention of pitch, ink, and stickies onto the fiber and minimizing the deposition of pitch, ink, and stickies particles on the paper machine or associated part.
a) adding an effective pitch, ink, and stickies controlling amount of bentonite having a high swelling capacity in water to a suspension of fiber in contact with the paper machine or an associated part thereof; and b) adding an effective amount of talc to the suspension in contact with the paper machine or an associated part thereof, thereby increasing retention of pitch, ink, and stickies onto the fiber and minimizing the deposition of pitch, ink, and stickies particles on the paper machine or associated part.
2. The method of Claim 1, wherein the talc is added to the suspension before the bentonite is added to the suspension.
3. The method of Claim 1 wherein the bentonite is added to the suspension before the talc is added to the suspension.
4. The method of Claim 1, wherein the bentonite and the talc are added simultaneously to the suspension.
5. The method of Claim 4, wherein the bentonite and the talc are added as a mixture to the suspension.
6. The method of any one of claims 1 to 5, wherein ratio of the bentonite talc is from about 1:1 to about 0.1:20.
7. The method of any one of claims 1 to 5, wherein from about 0.05 to about 20 kilograms of the talc per ton of fiber in suspension is added to the suspension.
8. The method of any one of claims 1 to 5 and 7, wherein from about 0.05 to about 10 kilograms of the bentonite per ton of fiber in suspension is added to the suspension.
9. A method for minimizing pitch, ink, and stickies particle deposits in a paper making process by causing retention of such particles onto fiber comprising the steps of:
a) adding an effective pitch, ink, and stickies controlling amount of bentonite having a high swellable capacity in water to a suspension of fiber in contact with the paper machine or an associated part thereof; and b) adding an effective pitch, ink, and stickles controlling amount of talc to the suspension in contact with the paper machine or an associated part thereof, wherein the ratio of bentonite to talc is from about 1:1 to about 0.1:20, thereby increasing retention of pitch, ink, and stickies onto the fiber and minimizing the deposition of pitch, ink, and stickies particles on the paper machine or associated part.
a) adding an effective pitch, ink, and stickies controlling amount of bentonite having a high swellable capacity in water to a suspension of fiber in contact with the paper machine or an associated part thereof; and b) adding an effective pitch, ink, and stickles controlling amount of talc to the suspension in contact with the paper machine or an associated part thereof, wherein the ratio of bentonite to talc is from about 1:1 to about 0.1:20, thereby increasing retention of pitch, ink, and stickies onto the fiber and minimizing the deposition of pitch, ink, and stickies particles on the paper machine or associated part.
10. The method of Claim 9, wherein the bentonite and talc are added simultaneously to the suspension.
11. The method of Claim 10, wherein the bentonite and the talc are added as a mixture to the suspension in contact with the paper machine and associated parts.
12. The method of Claim 9, wherein the talc is added to the suspension before the bentonite is added to the suspension.
13. The method of Claim 9 wherein the bentonite is added to the suspension before the talc is added to the suspension.
14. The method of any one of claims 9 to 13, wherein from about 0.05 to about 20 kilograms of the talc per ton of fiber in suspension is added to the suspension in contact with the paper machine and associated parts.
15. The method of any one of claims 9 to 14, wherein from about 0.05 to about 10 kilograms of the bentonite per ton of fiber in suspension is added to the suspension in contact with the paper machine and associated parts.
16. A method for minimizing pitch, ink, and stickie particle deposits in a paper making process by causing retention of such particles onto fiber comprising the steps of:
a) adding to a suspension in contact with a paper machine or an associated part thereof, from about 0.005 to about 0.5% by weight based on fiber in suspension of a flocculant;
b) subjecting the suspension to at least one shear stage;
and c) adding to the suspension from about 0.005 to about 0.5 by weight based on the fiber in suspension of bentonite and talc, thereby increasing retention of pitch, ink, and stickles onto the fiber and minimizing the deposition of pitch, ink, and stickies particles on the paper machine or associated part thereof.
a) adding to a suspension in contact with a paper machine or an associated part thereof, from about 0.005 to about 0.5% by weight based on fiber in suspension of a flocculant;
b) subjecting the suspension to at least one shear stage;
and c) adding to the suspension from about 0.005 to about 0.5 by weight based on the fiber in suspension of bentonite and talc, thereby increasing retention of pitch, ink, and stickles onto the fiber and minimizing the deposition of pitch, ink, and stickies particles on the paper machine or associated part thereof.
17. The method according to Claim 16, wherein the suspension is selected from the group consisting of fine paper, board, and grades made from mechanical pulps.
18. The method according to Claim 16 or 17, wherein the flocculant is selected from the group consisting of cationic, nonionic, and anionic polymeric flocculants.
19. The method according to Claim 16, 17 or 18, wherein the talc is added to the suspension before the bentonite is added to the suspension.
20. The method according to Claim 16, 17 or 18, wherein the talc and the bentonite are added simultaneously to the suspension.
21. The method of Claim 20, wherein the bentonite and the talc are added as a mixture to the suspension.
22. The method of Claim 16, 17 or 18, wherein the bentonite is added to the suspension before the talc is added to the suspension.
23. The method according to any one of claims 16 to 22, wherein the ratio of the talc to the bentonite is from about 0.1 to about 5.
24. The method according to any one of claims 16 to 23, wherein from about 0.05 to about 20 kilograms of the talc per ton of fiber in suspension is added to the suspension.
25. The method according to any one of claims 16 to 23, wherein from about 0.05 to about 10 kilograms of the bentonite per ton of fiber in suspension is added to the suspension.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/646,000 | 1996-05-14 | ||
| US08/646,000 US5798023A (en) | 1996-05-14 | 1996-05-14 | Combination of talc-bentonite for deposition control in papermaking processes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2205277A1 true CA2205277A1 (en) | 1997-11-14 |
Family
ID=24591336
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002205277A Abandoned CA2205277A1 (en) | 1996-05-14 | 1997-05-13 | Combination of talc-bentonite for deposition control in papermaking processes |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5798023A (en) |
| CA (1) | CA2205277A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| EP2546410A1 (en) | 2011-07-11 | 2013-01-16 | Omya Development AG | Hydrophobised calcium carbonate particles |
| EP2933375A1 (en) | 2014-04-16 | 2015-10-21 | Omya International AG | Adsorbing and/or reduction of the amount of organic materials in an aqueous medium by using colloidal precipitated calcium carbonate |
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| WO2001004417A1 (en) * | 1999-07-09 | 2001-01-18 | Naintsch Mineralwerke Gmbh | Use of talcum in the manufacture of paper and a method for the same |
| FI19992598A7 (en) * | 1999-12-02 | 2001-06-03 | Kemira Oyj | Method for making paper |
| US6405582B1 (en) * | 2000-06-15 | 2002-06-18 | Hercules Incorporated | Biosensor and deposit sensor for monitoring biofilm and other deposits |
| GB0115411D0 (en) * | 2001-06-25 | 2001-08-15 | Ciba Spec Chem Water Treat Ltd | Manufacture of paper and paper board |
| US6939443B2 (en) * | 2002-06-19 | 2005-09-06 | Lanxess Corporation | Anionic functional promoter and charge control agent |
| US20060048908A1 (en) * | 2004-09-08 | 2006-03-09 | Enzymatic Deinking Technologies, Llc | System for control of stickies in recovered and virgin paper processing |
| DE102004060587A1 (en) * | 2004-12-16 | 2006-07-06 | Süd-Chemie AG | Bentonites for impurity binding in papermaking |
| US7449086B2 (en) * | 2005-09-21 | 2008-11-11 | Nalco Company | Use of synthetic metal silicates for decreasing the deposition of contaminants during a papermaking process |
| FR2900410B1 (en) * | 2006-04-27 | 2008-08-29 | Coatex Sas | PROCESS FOR TREATING TALC WITH AMPHOTERIC POLYMERS, TALC OBTAINED, USE OF SAID TALC AS A REDUCING AGENT OF THE QUANTITY OF COLLOIDS IN THE MANUFACTURE OF AQUEOUS SYSTEMS. |
| FR2900411B1 (en) * | 2006-04-27 | 2008-08-29 | Coatex Sas | PROCESS FOR THE TREATMENT OF MINERAL MATERIALS BY AMPHOTERIC POLYMERS, THE MINERAL MATERIALS OBTAINED, THEIR USE AS A REDUCING AGENT OF THE QUANTITY OF COLLOIDS IN THE MANUFACTURE OF PAPER. |
| DE102006061046A1 (en) * | 2006-12-22 | 2008-06-26 | Omya Development Ag | Preparation of raw bentonite |
| ES2392017T3 (en) * | 2008-03-15 | 2012-12-04 | Hercules Incorporated | Clay pastes and their use in paper and pulp manufacturing applications |
| US8105988B2 (en) * | 2008-10-06 | 2012-01-31 | Nalco Company | Corrosion inhibitors for a fluid |
| US8105987B2 (en) * | 2008-10-06 | 2012-01-31 | Nalco Company | Corrosion inhibitors for an aqueous medium |
| EP2376707A1 (en) * | 2008-12-15 | 2011-10-19 | IMI Fabi S.p.A. | Talc- and/or chlorite-based compositions and use thereof in controlling pollutants in papermaking industry processes |
| US7989403B2 (en) * | 2009-03-02 | 2011-08-02 | Nalco Company | Corrosion inhibitors containing amide surfactants for a fluid |
| ES2730749T3 (en) * | 2010-06-11 | 2019-11-12 | Imerys Talc America Inc | Method for removal of contaminants in paper production |
| RU2473725C1 (en) * | 2011-08-16 | 2013-01-27 | Общество с ограниченной ответственностью "Оптимальные химические технологии+консалтинг" | Method of production of cardboard with white cover layer |
| FI127289B (en) | 2016-11-22 | 2018-03-15 | Kemira Oyj | Use of a polymer product for controlling precipitation in the manufacture of paper or paperboard |
| US11447914B2 (en) | 2017-12-07 | 2022-09-20 | Thiele Kaolin Company | Removal of stickies in the recycling of paper and paperboard |
| TWI914581B (en) * | 2022-01-17 | 2026-02-11 | 日商王子控股股份有限公司 | Oars for glass bonding, glass bonding and its manufacturing method |
| WO2025262365A1 (en) * | 2024-06-20 | 2025-12-26 | Kemira Oyj | Defects and extractive amount in pulp |
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| SE432951B (en) * | 1980-05-28 | 1984-04-30 | Eka Ab | PAPER PRODUCT CONTAINING CELLULOSA FIBERS AND A BINDING SYSTEM CONTAINING COLOIDAL MILIC ACID AND COTIONIC STARCH AND PROCEDURE FOR PREPARING THE PAPER PRODUCT |
| CA1194254A (en) * | 1980-11-28 | 1985-10-01 | Margaret J. Molnar | Diallyl dimethyl ammonium chloride polymers for pitch control |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2546410A1 (en) | 2011-07-11 | 2013-01-16 | Omya Development AG | Hydrophobised calcium carbonate particles |
| WO2013007717A1 (en) | 2011-07-11 | 2013-01-17 | Omya Development Ag | Hydrophobised calcium carbonate particles |
| US10322946B2 (en) | 2011-07-11 | 2019-06-18 | Omya International Ag | Hydrophobised calcium carbonate particles |
| EP2933375A1 (en) | 2014-04-16 | 2015-10-21 | Omya International AG | Adsorbing and/or reduction of the amount of organic materials in an aqueous medium by using colloidal precipitated calcium carbonate |
| WO2015158657A1 (en) | 2014-04-16 | 2015-10-22 | Omya International Ag | Adsorbing and/or reduction of the amount of organic materials in an aqueous medium by using colloidal precipitated calcium carbonate |
| US10046984B2 (en) | 2014-04-16 | 2018-08-14 | Omya International Ag | Adsorbing and/or reduction of the amount of organic materials in an aqueous medium by using colloidal precipitated calcium carbonate |
Also Published As
| Publication number | Publication date |
|---|---|
| US5798023A (en) | 1998-08-25 |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |