MXPA06008268A - Process for making paper. - Google Patents

Abstract

Methods for making paper or paperboard are described. One preferred method comprises forming a treated pulp by added to a papermaking pulp a synthetic layered silicate, a peptizer and at least one polymer. The synthetic layered silicate preferably comprises a synthetic hydrous sodium lithium magnesium silicate and the polymer is selected from cationic, nonionic and amphoteric polymers. The peptizer is preferably an inorganic polyphosphate peptizer and is contained in certain commercial synthetic layered silicate products. The inventor has surprisingly found that the peptizer provides significant improvements in drainage, retention and turbidity, thereby improving the papermaking process and the paper or paperboard product.

Description

PROCESS FOR MANUFACTURING PAPER FIELD OF THE INVENTION The present invention relates to pulps of papermaking, papermaking processes employing pulps, papermaking apparatus, and paper and cardboard products made from pulps. More particularly, the present invention relates to the treatment of papermaking pulp with at least one auxiliary retention system containing icroparticles. BACKGROUND OF THE INVENTION Auxiliary retention systems containing microparticles and other particulate materials have been added to papermaking pulps as process aids to improve retention and other properties such as formation and drainage. For example, U.S. Patent No. 5,194,120 to Peats et al., Herein incorporated by reference in its entirety, discloses an auxiliary retention system comprising a cationic polymer and an amorphous metal silicate material. One type of silicate material mentioned by the Peats et al. System is Laponite®, a synthetic layered silicate. According to Peats et al., The use of an auxiliary retention system comprising an amorphous metal silicate material and a cationic polymer provides various advantages, including improved retention, drainage and formation while minimizing the amount of polymer and silicate amorphous metal added to the pulp. The microparticle component of the auxiliary retention system is typically added to the papermaking pulp in the form of a low viscosity aqueous colloidal dispersion, i.e. a sol. One problem with the soles of microparticles used in papermaking pulps is instability. Due to the instability of the sols used in relation to papermaking pulps, the soles are often made on site for immediate supply to a papermaking process. There is a need for a stable microparticle sun retention aid for use in paper manufacturing processes that are to be formed off-site, exhibiting a long shelf life, and can be sent to a papermaking plant for immediate or future use in a papermaking process. There is also a need for a papermaking pulp that exhibits even better drainage and retention of fine products during a papermaking process. BRIEF DESCRIPTION OF THE INVENTION The present invention relates to the use of a combination of synthetic layered silicate microparticles, a peptizer and at least one polymer as an auxiliary retention system for a pulp or papermaking extract. The synthetic layered silicate is preferably a synthetic hydrated lithium magnesium sodium silicate and is preferably added to the papermaking pulp in the form of an aqueous colloidal dispersion which also contains the peptizer. The polymer can be a cationic polymer, a nonionic polymer, or an amphoteric polymer used under cationic conditions. The polymer is preferably a cationic polymer containing synthetic nitrogen, for example, a cationic polyacrylamide. If it is non-ionic, the polymer can be, for example, a non-ionic polyacrylamide or a polyethylene oxide. The peptizer is present in the dispersion of microparticles for the purpose of maintaining the dispersion in the form of a sol and preventing dispersion of the settlement to a gel for a determined period of time.

This allows the formation of relatively concentrated microparticle soles that can be formed off-site, which exhibit a relatively long shelf life and can be sent to the papermaking plant for immediate or permanent use. The inventor has unexpectedly found that certain microparticle dispersions that include a peptizer also provide significant improvements over dispersions of microparticles that do not employ a peptizer. For example, the inventor has found that the use of a retention aid that includes a dispersion of microparticles containing sodium silicate lithium magnesium hydrate and a peptizer significantly improves the retention of fine products, drainage and formation, thereby providing improvements in the papermaking process and in the paper product. In one aspect, the present invention provides a method of making paper or paperboard comprising: (a) forming a treated pulp by adding to a papermaking pulp a synthetic layered silicate, a peptizer and at least one polymer, the synthetic layered silicate comprising a synthetic lithium magnesium hydrated sodium silicate and at least one polymer comprising one or more members of the group consisting of cationic polymers, nonionic polymers and amphoteric polymers under cationic conditions; and (b) forming the pulp treated in the paper or cardboard. In another aspect, the present invention provides a papermaking apparatus comprising a supply of synthetic layered silicate, a supply of a papermaking pulp, a device for feeding the synthetic layered silicate from the layered silicate supply. Synthetic to the pulp supply of papermaking, a supply of a retention system polymer, a device for feeding the retention system polymer from the supply of the retention system polymer to the papermaking pulp, and a device to form the pulp in a paper or cardboard after treatment with the synthetic layered silicate and the retaining system polymer, wherein the retaining system polymer is a cationic polymer, a nonionic polymer or an amphoteric polymer under cationic conditions or 'combinations thereof and wherein the synthetic layered silicate comprises a silicate sodium lithium magnesium hydrated synthetic and is fed to the papermaking pulp in the form of an aqueous dispersion which also includes an inorganic polyphosphate peptizer. In still another aspect, the present invention provides a paper or paperboard made from a drained paper tape, the paper tape comprising a treated pulp, the treated pulp comprising cellulosic fibers, sodium silicate lithium magnesium hydrated synthetic, at least a retention system polymer and an inorganic polyphosphatide peptizer, the retention system polymer comprising a cationic polymer, a nonionic polymer, or an amphoteric polymer under cationic conditions, or combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example only, with reference to the accompanying drawings in which: FIG. 1 is a flow chart showing a papermaking process according to one embodiment of the present invention; FIG. 2 is a flow chart showing a papermaking process according to another embodiment of the present invention; FIG. 3 is a flow chart showing a papermaking process according to yet another embodiment of the present invention; FIG. 4 is a flow diagram showing a papermaking process according to yet another embodiment of the present invention; FIG. 5 is a flow chart showing a papermaking process according to yet another embodiment of the present invention; FIG. 6 is a bar graph showing the time to achieve drainage of 200 ml of filtrate from paper tapes made from several exemplary and comparative paper extract formulations; FIG. 7 is a bar graph comparing the turbidity of several exemplary and comparative paper extract formulations; FIG. 8 is a bar graph showing the retention% of the first total step (TFPR) of several exemplary and comparative paper extract formulations; FIG. 9 is a plot of time versus volume showing the drainage of several exemplary and comparative paper extract formulations; FIG. 10 is a bar graph showing the drainage in seconds of several exemplary and comparative paper extract formulations; and FIG. 11 is a bar graph showing retention for several exemplary and comparative paper extract compositions. DETAILED DESCRIPTION OF PREFERRED MODALITIES The present invention relates to the use of an auxiliary retention system for a papermaking pulp, the system comprising a synthetic layered silicate, a peptizer and at least one polymer. More than a type of microparticle, more than a type of peptizer and more than one type of polymer can be used in the process of the invention. Paper and paperboard products made according to the method preferably exhibit excellent opacity or other desirable physical properties. The pulp sheets from which the paper and cardboard products are made preferably exhibit excellent drainage and / or excellent retention of fine pulp products. The synthetic layered silicate preferably comprises a synthetic lithium magnesium hydrated sodium silicate which is manufactured and sold under the trademark Laponite® by Rockwood Additives Limited of Widnes, Cheshire, United Kingdom. These synthetic hydrated magnesium lithium sodium silicates are synthesized by combining sodium, magnesium and lithium salts with sodium silicate in carefully controlled proportions and temperatures. This produces an amorphous precipitate which is then partially crystallized under temperature and high pressure. The resulting product is filtered, washed, dried and milled to give a fine white powder. For greater certainty, the terms "sodium silicate lithium magnesium hydrated hydrate" and "sodium silicate lithium magnesium hydrate" as used herein include silicates that are identified by CAS No. 533320-86-8 and have the following analysis typical chemical (% p): Si02 59.5; MgO 27.5; Li20 0.8 Na20 2.8; loss in ignition 8.2. Such silicates typically comprise a free flowing white powder having a bulk density of 1,000 kg / m 3; surface area (BET) of 370 m2g; pH (2% suspension) of 9.8; sieve analysis (< 250 μm) of 98%; and moisture content of 10%. For greater certainty, the terms "sodium hydrous lithium magnesium hydrous silicate" and "hydrated magnesium lithium sodium silicate" as used herein do not include synthetic layer silicates identified by the name TSCA "sodium lithium magnesium fluorosilicate" hydrated "and by CAS No. 64060-48-6 and having the following typical chemical composition (% p-dry base): Si02 51.0; MgO 25.0; Li20 1.3 Na20 6.0; P205 3.3; F 5.0; loss in ignition 8.4. The synthetic layered silicate microparticles may be added in any amount sufficient to improve the retention of fine products or drainage or to reduce turbidity when the pulp or extract is formed in a wet sheet or tape. Preferably, the microparticles are added in an amount of at least about 0.02 kg / ton (0.05 lb / ton) of paper extract, based on the weight of dry solids of both the microparticles and the paper extract. More preferably, the microparticles are added in an amount of about 0.05 kg / ton (0.1 Ib / ton) of paper extract of approximately 2.3 kg / ton (5.0 lb / ton) of paper extract, of approximately 0.09 kg / ton (0.2 Ib / ton) to approximately 0.5 kg / ton (1.0 lb / ton), based on the dry solids weight of the paper extract. For purposes of this patent application, the terms "provision", "pulp", "extract" and "paper extract" are used interchangeably. Preferably, the synthetic layered silicate is added to the pulp in the form of a colloidal, aqueous dispersion of relatively low viscosity. A colloidal dispersion having these characteristics is known as a "sun." In addition to the synthetic layered silicate, the dispersion preferably also contains a peptizer in an amount sufficient to maintain the dispersion in the form of a sol for a predetermined period of time. The peptizer essentially stabilizes the sol to prevent it from settling to a gel for a period of time that depends at least partially on the concentration of the synthetic layered silicate. This allows the dispersion to be formed off-site at a reasonable concentration and then sent to the papermaking plant for immediate or future use. The peptizer is preferably a water soluble salt that increases the dispersion of the synthetic layered silicate, more preferably a sodium salt selected from the group comprising sodium carbonate, sodium metaphosphate, sodium methacrylate, sodium hydroxide, sodium chloride, sodium polyphosphate and sodium pyrophosphate. In the particularly preferred embodiments of the present invention, the peptizer is an inorganic polyphosphate, more preferably tetrasodium pyrophosphate. The preferred peptizer, tetrasodium pyrophosphate, is present in certain grades of sodium lithium magnesium hydrate silicate available from Rockwood Additives Limited, including Laponite RDS, Laponite XLS and Laponite DS. A particularly preferred grade of Laponite is Laponite RDS comprising sodium hydrated lithium magnesium magnesium silicate (CAS No. 53320-86-8) in combination with about 5% by weight of tetrasodium pyrophosphate. The Laponite RDS sols containing about 10% by weight of the Laponite concentration are stable for about 3 days. Preferably, the sol has a Laponite concentration of up to about 6% by weight that is stable for at least about 90 days. Suns having a concentration of microparticles in this range exhibit sufficiently long shelf life to allow them to be formed off-site for shipment and subsequent use in a papermaking process. As mentioned in the foregoing, the inventor has unexpectedly discovered that certain microparticle dispersions including a peptizer also provide significant improvements over microparticle dispersions that do not employ a peptizer. In particular, the inventor has found that the inclusion of a peptizer in the microparticle dispersion significantly improves the retention of fine products, drainage and formation, thereby providing improvements in the papermaking process and in the paper product. For example, the inventor has found that the Laponite RDS containing the tetrasodium pyrophosphate peptide (TSPP), provides significantly increased drainage and retention, with lower turbidity than equivalent amounts of Laponite RD. Without being related by theory, it is believed that when the TSPP is mixed and dissolved in a colloidal dispersion of Laponite, the pyrophosphate ions become associated with the positively charged edges of the Laponite crystals, making the complete particle negatively charged This effectively increases the negative charge on the Laponite crystals and causes them to have a greater attraction to the cationic particles present in the papermaking process. The polymer is preferably added to the papermaking pulp before the addition of the microparticles, any order of addition can be used. Preferably, the polymer can be any polymer that does not adversely affect the formation of pulp or paper and may preferably comprise a coagulant and / or a flocculant. Preferably, the polymer is a medium for the synthetic polymer of high molecular weight, for example, a polymer containing cationic nitrogen such as cationic polyacrylamide or copolymer thereof or a cationic diallyldimethylammonium chloride or a copolymer thereof. The polymer can be cationic, non-ionic or amphoteric. If it is amphoteric, the polymer is preferably used under cationic conditions. At least one other polymer of any kind can be used in addition to the polymers mentioned above provided that the at least one other polymer substantially does not adversely affect the retention properties of the present invention. The at least one other polymer can preferably be a polyamidoamine glycol polymer (OPAAG). The polymer preferably has a molecular weight in the range of from about 10,000 to about 25,000,000 and more preferably from about 500,000 to about 18,000,000 although other molecular weights are possible to achieve the proposed effect. The polymer may preferably be a high molecular weight linear cationic polymer or a crosslinked polyethylene oxide. Exemplary high molecular weight linear cationic polymers and shear stage processing suitable for use in the pulps and methods of the present invention are described in U.S. Patent Nos. 4,753,710 and 4,913,774 to Langly et al., Both of which they are incorporated into the present in their totals by reference. The polymer is preferably added before at least one of the significant shear stages of the papermaking process and can be added in more than one step. The microparticles can be added before or after the various stages of significant shear of the papermaking process. According to some embodiments of the present invention, the polymer can be added before the microparticles and then at least one step of negligible shearing in the papermaking process. If the polymer is added before the microparticles, the microparticles can be added before or after a final shear stage of the papermaking process. Although it is preferable to add the polymer to the papermaking pulp before the last point of shear in the papermaking process, the polymer can be added after the last point of shear. The microparticles preferably form bridges or structures between various particles. The polymer preferably binds partially (eg, absorbed) on the surfaces of the particles within the extract and can provide binding sites. The pulp or aqueous cellulose paper manufacturing extract can be treated first by adding the polymer to the pulp or extract, followed by submitting the paper extract to high shear conditions, then by adding the microparticles prior to sheet formation. As discussed in the above, the polymer can be cationic, non-ionic or amphoteric under cationic conditions. Alternatively, the polymer can be added simultaneously with synthetic layered silicate microparticles. Preferred cationic polyacrylamides for use as the retention system polymer are described in more detail below. If a cationic polyacrylamide is used as the cationic polymer, the cationic polyacrylamide can have a molecular weight in excess of 100,000 and preferably has a molecular weight of about 500,000 and 18,000,000. The combination of polymer and synthetic layered silicate microparticles preferably provides an adequate balance between freedom, dewatering, retention of fine products, good paper formation, firmness and shear resistance. The polymer composition of the retention system is added in an effective amount to preferably improve drainage or retention of the pulp compared to the same pulp but which has no polymer present. The polymer is preferably added in an amount of at least about 0.005 kg / ton (0.01 Ib / polymer per ton) of paper extract based on the weight of dry solids of both the polymer and the paper extract. More preferably, the polymer is added in an amount of about 0.005 kg / ton (0.1 Ib / ton) of paper extract of about 2.3 kg / ton (5 Ib / ton) of paper extract, to one more preferably 0.09 g / ton (0.2 lb / ton) to approximately 1 kg / ton (2 lb / ton) based on the dry solids weight of the paper extract, although other quantities may be used. If the polymer is cationic, any cationic polymer or mixture thereof can be used and preferably conventional cationic polymers commonly associated with papermaking can be used in the pulps or extracts in the present invention. Examples of cationic polymer include, but are not limited to cationic starches and cationic polyacrylamide polymers, for example, copolymers of an acrylamide with a cationic monomer, wherein the cationic monomer may be in a neutralized or quaternized form. Preferred are cationic polymers containing nitrogen. Exemplary cationic monomers which can be copolymerized with acrylamide to form preferred cationic polymer useful according to the present invention, include aminoalkyl esters of acrylic or methacrylic acid, and allylamines in either neutralized or cuternized form. Exemplary cationic monomers and cationic polyacrylamide polymer are described in U.S. Patent No. 4,894,119 to Baron, Jr., et al., Which is incorporated herein by reference in its entirety. The polymer can also be a polyacrylamide formed from comonomers including, for example, l-trimethylammonium-2-hydroxypropyl methacrylate methosulfate. Other examples of cationic polymerizers include, but are not limited to homopolymers of diallylamine monomers, aminoalkyl ester homopolymers of acrylic acids and polyamines, as described in U.S. Patent No. 4,894,119. Copolymers, terpolymers, or higher forms of polymers can also be used, furthermore, for purposes of the present invention, a sample of two or more polymers can be used. In embodiments where the polymer contains a cationic polyacrylamide, nonionic polyacrylamide units are preferably present in the copolymer, preferably in an amount of at least about 30 mol% and generally in an amount of not more than 95 mol%. Of about 5 mol% of about 70 mol% of the polymer is preferably formed of a cationic monomer. The pulp or papermaking extract can be any conventional type, and, for example, may contain cellulose fibers in an aqueous medium in a concentration of preferably at least about 50% by weight of total dry solids content in the pulp or extract. The retention system of the present invention can be added to many different types of pulp, papermaking extract or pulp or extract combinations. For example, the pulp may comprise virgin and / or recycled pulp, such as virgin sulphite pulp, broken pulp, a hardwood kraft pulp, a softwood kraft pulp, mixtures of such pulps, the like. The auxiliary retention system can be added to the pulp or extract in advance to deposit the pulp or extract on a papermaking wire. The pulp or extract containing the auxiliary retention system has been found to exhibit good dewatering during the formation of the paper tape on the wire. The pulp or extract also exhibits a desirable high retention of fine fiber products and fillers in the paper tape products under conditions of high shear stress imposed on the pulp and extract.

. In addition to the auxiliary retention system used in accordance with the present invention, the pulp or papermaking extract according to the present invention may additionally contain other types of microparticles. One or more different types of secondary microparticle additives, other than the synthetic layered silicate microparticles, can be added to the pulp at any time during the process. The secondary microparticle additive may be natural or synthetic hectorite, bentonite, zeolite, non-acidic alumina sol, or. any of the conventional particulate additives as known to those skilled in the art. Exemplary synthetic microparticles are described in U.S. Patent Nos. 5,571,379 and 5,015,334, which are incorporated herein by reference in their entireties. In addition to the auxiliary synthetic layered silicate microparticle retention system used in accordance with the present invention, the pulps or papermaking extracts according to the present invention may additionally contain a coagulant / flocculant retention system having a different composition than the retention system of the present invention. The papermaking pulps of the present invention may also contain an enzyme that treats conventional papermaking pulp having cellulite activity. Preferably, the enzyme composition also exhibits hemicellulitic activity. Suitable enzymes and compositions containing enzymes include those described in U.S. Patent Nos. 5,356,800 and 6,324,381 to Jaques, and International Publication No. WO 99/43780, all incorporated herein by reference in their entireties. Other exemplary papermaking pulp treating enzymes are BUZIMW ™ 2523 and BUZIME ™ 2524 both available from Buckman Laboratories International, Inc., Memphis Tenn. A preferred cellulitic enzyme composition preferably contains from about 5% by weight to about 20% by weight of enzyme. The preferred enzyme composition may additionally contain polyethylene glycol, hexylene glycol, polyvinyl pyrrolidone, tetrahydrofuryl alcohol, glycerin, water and other conventional enzyme composition additives, such as, for example, described in U.S. Patent No. 5,356,800. The enzyme can be added to the pulp in any conventional amount, such as in an amount of about 0.001% by weight to about 0.100% by weight of enzyme based on the dry weight of the pulp, for example, about 0.05% by weight . In a preferred embodiment of the present invention, an enzyme composition is included in the pulp and extract and contains at least one oligomer of polyamide and at least one enzyme. The polyamide is present in an amount effective to stabilize the enzyme. Exemplary enzyme compositions containing polyamide oligomers and enzymes are described in International published application No. WO 99/43780, which is hereby incorporated by reference in its entirety. If an enzyme composition is included, it may include a combination of two or more different enzymes. The enzyme composition may include, for example, a combination of a lipase and a cellulose, and optionally may include a stabilizing agent. The stabilizing agent can be a polyamide oligomer as described herein. A particular additive for use according to the methods of the present invention is a cationic starch. The cationic starch can be added to the pulp or extract of the present invention to form a pulp treated with starch. The starch may be added at one or more points along the flow of the papermaking pulp through the papermaking apparatus or system of the present invention. For example, the cationic starch may be added to a pulp at about the same time that the acidic aqueous alumina sol is added to the pulp. Preferably, if a cationic starch is used, it is added to the pulp or combined with the pulp before the introduction of the synthetic layered silicate microparticles to the pulp. The cationic starch may alternatively or additionally be added to the pulp after the pulp is first treated with an enzyme, a coagulant, or both. Preferred cationic starches include, but are not limited to, potato starches, corn starches, and other wet finished starches or combinations thereof. Conventional amounts of starch can be added to the pulp. An exemplary amount of starch that can be used according to the present invention is from about 2.68 to about 11.34 kilograms per ton (5 to about 25 pounds per ton) based on the weight of dry pulp solids. A biocide can be added to the pulp according to conventional uses of biocides in papermaking processes. For example, a biocide can be added to the treated pulp in a mixing box after the pulp has been treated with the enzyme and optional polymer. Useful biocides in the papermaking pulps according to the present invention include biocides well known to those skilled in the art, for example, biocides available from Buckman Laboratories International, Inc., Memphis, Tenn, such as BUSAN ™ biocides.

The pulps or extracts of the present invention can be further treated with one or more other components, including polymers such as anionic and non-anionic polymers, clays, other fillers, dyes, pigments, defoamers, pH adjusting agents such as alum , microbiocides, and other conventional papermaking additives or processing. These additives can be added before, during or after the introduction of the synthetic layered silicate microparticles. Preferably, the synthetic layered silicate microparticles are added much later, if not all, other additives and components are added to the pulp. Thus, synthetic layered silicate microparticles can be added to the papermaking pulp after the addition of conventional and nonconventional enzymes, coagulants, flocculants, fillers and other papermaking additives. The addition of the retention system according to the present invention can be practiced in most, if not all, conventional papermaking machines. A flow chart of a papermaking system for carrying out one of the methods of the present invention is set forth in FIG. 1. It will be understood that the system shown is exemplary in the present invention and is in no way intended to restrict the scope of the invention in the system of FIG. 1, an optional supply of the enzyme composition in a desired concentration is combined with a flowing stream of the papermaking pulp to form a treated pulp. The supply of the pulp shown represents a flow of pulp, as for example, supplied from a tank or silo retention of the pulp. The pulp supply shown in FIG. 1 can be a duct, a holding tank or a mixing tank, or another container, passage, or mixing zone for the flow of pulp. The supply of the enzyme composition can be, for example, a holding tank having an outlet in communication with an inlet of a treated pulp tank. The pulp treated with the enzyme composition is passed from the treated pulp tank through a refiner and then through a mixing box where the optional additives, eg, a biocide, can be combined with the treated pulp. The refiner has an input in communication with an outlet of the treated pulp tank, and an outlet in communication with an inlet of the mixing box. According to the embodiment of FIG. 1, the pulp treated in the mixing box is passed from an outlet of the mixing box through a communication to an inlet of a machine box where the optional additives can be combined with the treated pulp. The mixing box and the machine box may be of any conventional type known to those skilled in the art. The machine box ensures a level head which is a constant pressure on the pulp or extract treated by the entire downstream portion of the system, particularly in the headbox. From the machine box, the pulp is passed to a silo of frothy water and then to a fan pump. The retention system polymer of the present invention preferably introduces into the flow of the pulp between the silo and the fan pump. The supply of the retention system polymer composition can be, for example, a holding tank having an outlet in communication with a line between the foaming water silo and the fan pump. As the pulp passes from the fan pump to a screen, the synthetic layered silicate microparticles are preferably added. Conventional valves and pumps used in connection with the introduction of conventional additives can be used. The sifted pulp goes to a head box where a sheet of wet paper is made on a wire and drained. In the system of FIG. 1, the drained pulp that results from the manufacture of paper in the head box is recirculated to the silo of foamed water. In the embodiment shown in FIG. 2, the synthetic layered silicate microparticles are first added to the refined treated pulp between the foamed water silo and the fan pump. The retention system polymer is then added to the fan pump and before the screen. Another embodiment of the present invention is shown in FIG. 3. A pulp optionally treated with a cationic starch is refined, passed to a mixing box, passed to a machine box, and then passed to a silo of foaming water. Between the foamed water silo and the fan pump the retention system polymer is preferably added to the pulp. The synthetic layered silicate microparticles are preferably added after the pulp passes through the screen and just before the formation of the sheet in the head box. The apparatus of the present invention may also include metering devices to provide an adequate concentration of the synthetic layered silicate microparticles of other additives to the pulp flow. A cleaner, for example, a centrifugal force cleaning device, may be placed between, for example, the fan pump and the screen, according to any of the embodiments of FIGS. 1-3 previous.

Figures 4 and 5 are flow charts illustrating the steps of adding the polymer and the microparticles in two particularly preferred embodiments of the present invention. It will be appreciated that Figures 4 and 5 illustrate only those components (ie the fan pump, screen and headbox) and the addition steps which are necessarily to describe the steps of adding the polymer and microparticles in these preferred processes, and that the processes and apparatuses illustrated in Figures 4 and 5 may preferably include some or all of the optional additives, apparatus components and / or process steps shown in Figures 1 through 3 and described in the foregoing. The pulp passes through the apparatus of Figures 4 and 5 in the direction indicated by the arrows, passing through the fan pump and the screen on its way to the headbox. The pulp is divided both for the fan pump and for the screen, however the shear applied to the pulp by the screen is greater than that applied to the fan pump, so that the screen is the high shear stage final in the papermaking process prior to the entry of the pulp into the headbox of the papermaking apparatus. In both Figures 4 and 5, a coagulating polymer is preferably added before the fan pump. The coagulant preferably comprises a high cationic, relatively low molecular weight density polymer for purifying and collecting colloidal particles, primarily anionic fibers and fillers. The colloidal particles coagulate to form macro-colloids that are larger in size and more easily retained in the leaf in the drain. The coagulant is preferably a polyamine or a diallyldimethylammonium chloride polymer (DADMAC), or copolymers thereof. A particularly preferred coagulant for use in the processes illustrated in Figures 4 and 5 is BUFLOC ™ 5376, available from Buckman Laboratories International, Inc., which is a cationic DADMAC having a loading density of 95% and a molecular weight of about 500,000. The coagulating polymer is preferably added to the pulp in an amount of from about 0.05 to about 1.0 kg / ton of pulp on a dry basis, more preferably from about 0.1 to about 0.5 kg / ton and even more preferably about 0.3 kg / ton. The processes of Figures 4 and 5 both include the addition of an auxiliary retention system containing microparticles comprising a retention system polymer and a microparticle. The microparticle is a synthetic layered silicate, more preferably a synthetic lithium magnesium hydrated sodium silicate, and even more preferably a synthetic lithium magnesium hydrated sodium silicate in combination with a peptizer, the much more preferred peptizer being tetrasodium pyrophosphate. The microparticle preferably comprises one or more of Laponite RDS, XLS and DS, and more preferably comprises Laponite RDS. The microparticle is preferably added in an amount of from about 0.1 to about 1.0 kg / ton of pulp on a dry basis, more preferably from about 0.2 to about 0.6 kg / ton and even more preferably about 0.4 kg / ton. The polymer of the retention system is preferably a flocculant and may preferably comprise any of the cationic polymers containing synthetic nitrogens described in the foregoing. A particularly preferred retention system polymer is BUFLOC ™ 5511, available from Buckman Laboratories International, Inc., which is a cationic polyacrylamide having a molecular weight of about 10,000,000. The retention system polymer is preferably added to the pulp in an amount of about 0.05 to 1.0 kg / ton of pulp on a dry basis, more preferably from about 0.05 to about 0.5 kg / ton and even more preferably from about 0.1 to about 0.2 kg / ton.

The flow diagrams of Figures 4 and 5 differ from one another in the order of addition of the retention system polymer and the microparticle. In Figure 4, the microparticle is added before the screen, more preferably between the fan pump and the screen, while the retention system polymer is added after the screen, more preferably between the screen and the head box . In Figure 5, the order of addition is inverse, with the polymer that is added before the screen more preferably between the fan pump and the screen, and the microparticle that is added after the screen, more preferably between the screen and the head box. The order of addition is preferred in Figure 5. The invention is further described in. The following examples. EXAMPLES In the examples below, various components used in the examples are abbreviated. In the examples, the components identified as "RD", "RDS" and "JS" are Laponite RD, Laponite RDS and Laponite JS respectively, available from Rockwood Additives Limited. Laponite RD is a sodium silicate lithium magnesium hydrate; Laponite RDS is a lithium magnesium sodium silicate hydrated with tetrasodium pyrophosphate; and Laponite JS is a sodium lithium magnesium fluorosilicate hydrated with tetrasodium pyrophosphate. When followed by a numerical value, for example, "RDS 0.5", the numerical value represents the amount of pounds on a dry basis of the Laponite microparticles per ton of paper extract based on the weight of the dry solids of the extract of paper. In the examples below, the abbreviations "B 594" and "594" represent BUFLOC ™ 594, available from Buckman Laboratories International, Inc., which is a high molecular weight cationic polyacrylamide having. an average molecular weight of approximately 5,000,000 to approximately 7,000,000 units and 21% charge density. When followed by a numerical value, for example, "594 0.5", the numerical value represents the amount of pounds on a dry basis of the Bufloc 594 polymer per ton of paper extract based on the weight of dry solids in the paper extract. The abbreviations "B 5511" and "5511" represent BUFLOC ™ 5511, available from Buckman Laboratories International, Inc., which is a cationic polyacrylamide having a molecular weight of approximately 10,000,000. When followed by a numerical value, for example, "5511 0.5", the numerical value represents the amount of pounds on a dry basis of the Bufloc 5511 polymer per ton of paper extract based on the dry solid weight of the paper extract.

In samples where both the polymer and a microparticle component are added, the order of addition is specified. For example, the abbreviation "B 5511 0.5 / RDS 0.5" indicates that the Bufloc 551 polymer component is added to the supply after the Laponite RDS microparticle component. This simulates a papermaking process in which the microparticle is added before the final high shear stage (typically before the screen) and the polymer is added after the final high shear stage (typically between screen and the head box). Example I - Drain and Turbidity Tests The tests were conducted in a paper mill. Drainage was performed using a small sieve through which the 500 ml samples were drained using a modified Schieper Riegler method. The mixing was carried out in a food mixer. The equipment used for the modified Schopper Riegler drainage test included the following: a Schieper Riegler Modified (MSR); a recorded cylinder of 1000 mi; chronometer; a 18.9 1 (5-gallon) plastic bucket; wires for MSR; a flask and a vacuum funnel (for retention); Whatman ash filter papers (for ash retention); a turbidity meter; a hemocytometer; and a microscope.

The samples to be tested were taken from the headbox of the papermaking apparatus. For each test, 1000 ml was required. Because the temperature has an 'impact on the drain, each test was run immediately after the sample was taken. For laboratory studies with retention aids, the provision was kept at the same temperature as the temperature of the headbox. If the MSR was cooled and the sample heated, the MSR was heated while running, hot water on the outside and the inside of the MSR. If there was no hot water available, cold water was used. All the tests were conducted in the same way. It was hyperactive that the MSR wire was avoided from any of the fibers or fine products. The wire was flushed again with water before the test run. The distribution of fiber, fine products and uniform fillers in the mixture secured by agitating the fiber suspension in the cuvette. 1000 ml of the suspension was measured in a graduated cylinder and emptied into the MSR while holding the plunger down. The graduated cylinder was placed under the MSR. The plunger was then released and the chronometer started at the same time. The time required for drainage of the sample in incremented units of 100 ml was measured and recorded the incremented units of 100 ml selected were simply empirical. For example, samples of extract that drain very slowly were measured instead in 100, 150 and 200 ml drainage times. Sometimes several tests were necessary to determine the start volume tests. The different polymer levels in the various samples were compared, and for this purpose, the samples of the provision were obtained from the machine before the addition of the retention / drainage aid. The drainage and retention values were compared against the white provisions to determine the improvement. To measure the retention performance, the MSR filtrate was filtered through a pre-weighed filter paper, dried in a 105 ° C to 120 ° C oven and weighed again. The weight difference was recorded in g / ml. Drainage times were compared based on the different levels of additives (ie polymer and / or microparticle) in the provision. Drain times were recorded in seconds for each volume level. The total suspended solids were estimated with a turbidity meter. The filtrate could also have been filtered to determine the suspended solids. The solid contents of the MSR filtrate could be reported in mg / ml and are used to indicate the retention capabilities of different systems, with lower numbers indicating better retention. For repeated tests, the sample was taken from the same place throughout the papermaking system. It was ensured that the composition of the provision was the same for the repeated test. Repeated tests that did not match within the reason with a corresponding original test were suspect. The MSR was kept clean and rinsed constantly with water to protect the residual fibers from the buildup on the sides. The screen was cleaned periodically to remove the resin buildup and cleaned with a mild detergent brush. The wires were checked to ensure that bent or damaged wires were not used. All the tests were conducted in the same way and in the same consistency. The paper mill used a newspaper supply comprising 70% by weight of thermomechanical pulp (TMP) and 30% de-inked pulp (DIP). The pulp had a headbox conductivity of 1,000 icrosiemens, a cationic requirement of 0.15 ml / 1 of solution N 0.001 and a consistency of 0.65. The pH of the head box of the paper extract was 4.83. The additives combined with the paper extract included calcined clay as a filler in an amount of 2% by weight based on the weight of dry solids of the paper extract. The calcined clay was present in the DIP component. The polymer was added to the extract of. paper in varying quantities up to 0.35 kg / ton, (0.75 lg / ton) of paper extract, based on the weight of dry solids of both the polymer and the paper extract. ' The microparticle was added to the paper extract in varying amounts up to 0.46 kg / ton (1.0 lb / ton). All microparticle dosages were calculated on the dry basis. The results of the tests are shown in Tables 1 and 2 below. (Table 1 will contain the drainage / turbidity data and Table 2 will contain the retention data). In Table 1, the headings in column "100", "150", "200" and "250" represent the number of milliliters of collected filtrate that was drained through the wire. The corresponding numbers below the column headings represent the number of seconds needed for the respective number of milliliters (mi) of the filtrate to drain through the wire and be collected. For example, in the first entry of the Table 1, the paper extract identified as "white", (which has no microparticle retention system) required 27 seconds for 100 ml of filtrate to be drained through the forming wire and be collected, requiring 58 seconds for 150 ml of filtered to be collected, and required 90 seconds for 200 ml of the filtrate to be collected. In Table 1, turbidity, measured in nephelometric turbidity units (NTU), is listed in the last column. For each of the varisamples tested and reported in Table 1 that include both a microparticle additive and a polymer, in order of addition specified in the Table. For example, in samples 5 through 7 and 11 through 13 of Table 1, the polymer was first added. In samples 8 to 10 the microparticle was added first. TABLE I - Drainage and Turbidity * All sample compositions in lb / ton The data shown in Table 1 are plotted in Figures 6 and 7. Example 2 - Retention Tests The Britt Jar tests were performed at 1,000 rpm to evaluate the performance of the auxiliary system of retention based on the retention of the first step increased and the ash retention of the first step increased. In the Britt Jar, the supply is under continumovement, so that no fiber mat is formed and water can be drained continuy through the wire. This simulates the dewatering of extract and the water that occurs in the paper machine. The provision used in the Britt Jar tests was identical to the provision used in Example 1. In the Britt Jar tests, the chemicals are applied in the correct sequence and the provision is mixed to a degree to stimulate the treatment of the provision for the paper machine equipment such as fan pumps and centrifugal pumps. As this is cut, the extract passes a second (by far) currently in the fan pump or the screens. Another way to stimulate the shear stress and represent the current short contact time is to carry out all the chemical mixing outside the holding tester Britt Jar. The chemical additive mixing is carried out using a common hhold food mixer. The mixing process is the same for retention as well as drainage work.

All high shear mixing is carried out outside the Britt Jar using a feed mixer since this is more representative of the high shear points in the papermaking process. This also prevents plugging of the Britt Jar wire. Each chemical addition is followed by a short interruption of two seconds in the food mixer. This simulates the extract (including coagulant, starch, high molecular weight polymer) that goes through to the fan pump. To simulate the addition of the polymer pre-screen or the microparticle component, an interruption of a second cut in the feed mixer is used. To stimulate the addition of the polymer or microparticle post-sieve, the treated extract mixture is emptied into a cylinder, followed by the addition of the polymer or the microparticle component and the four-stroke inversion of the Britt Jar. The following equipment was used in the Britt Jar tests: Britt Jar tester; wires - 80P for newspaper supplies; Preconditioned ashless filter papers - Whatman # 41 or 43; diluted polymer samples; samples of extract (at least 20 liters); balance of 0.001 g; buchner funnel; drying oven; Kiln for determination of ash; plastic containers with lids; syringes - 1, 5 and 10 L; and a mixer - standard homemade food mixer with pulse characteristics. Each of the samples of extract and polymer were prepared as follows: prepare the samples of extract and polymer; make sure that the wire for the Britt Jar is wet; adjust the Britt Jar speed at the required set point and turn it on; mix the chemicals in the extract; empty the treated extract in the Britt Jar; wait 5 seconds, open the clamp and start filtering collection; collect first 100 ml of the filtrate; filter the filtrate through the preconditioned filter papers and dry the oven at 110 ° C; and calculate the% of TFPR. If ash-dried filter papers are required to determine the% FPAR. If ash-dried filter papers are required to determine the% FPAR. Calculations 1. Consistency =% of solids in the sample, and is represented by [] symbol = 100 x (weight of suspended solids) / (weight or volume of the original sample) 2. Retention of First Step, FPR =% solids HB retained in the sheet = ([HB] - [TW]) / [HB] x 100 Example: [HB] = 0.75%, [TW] = 0.18% FPR = 100 (0.75-0.18) /0.75 = 76% Withholding of ash from the first step, FPAR = ([HB ash] - [ash TW]) / [HB ash] x 100 [HB ash] is determined by HB ash, then multiplying% ash value by [HB ] is determined by the TW ash, then multiplying the% ash value by [RW]. The results of the retention tests are shown below in Table 2. TABLE 2 - Retention The data shown in Table 2 is illustrated graphically in Figure 8. Example 3 - Drain Tests Comparing Laponite RD, RDS and JS Drain tests were conducted on an alkaline supply followed by the procedure described in Example 1. All samples containing a microparticle also contained a polymer, Bufloc 5511, in most of these tests, Bufloc 5511 was added to the supply before the microparticle. For the tests, Laponite RDS were also conducted with the reverse order of addition. The results of the drainage test are illustrated in Figures 9 and 10. As shown in these Figures, the provision containing Laponite RDS had better drainage properties than the provision containing either Laponite JS or Laponite RD. In addition, the drainage results using RDS were better when the polymer (Bufloc 5511) was added before the Laponite RDS than when Laponite RDS was added to the latter. Example 4 - Retention Tests Comparing Laponite RD, RDS and JS The Britt Jar tests as described in Example 2 were performed using various combinations of polymer (Bufloc 5511) and microparticles. The tests were carried out with a supply of fine alkaline paper comprised of 60% hardwood and 40% softwood, which has a pH of 7.9, a conductivity of 670 microsiemens and a ash content of 20% -of calcium carbonate. precipitate (PCC) added to the machine box in the paper process. The retention data, which includes both the retention of the first total step (TFPR) and the retention of. ash of the first step (FPAR) is shown immediately in Table 3 and is also illustrated in Figure 11.

TABLE 3 As shown in Table 3 and Figure 11, the retention results for the Laponite RDS were better than the results obtained for the comparable concentrations of Laponite JS and Laponite RD. Also, the results show that the addition of Bufloc 5511 followed by the addition of Laponite RDS provided the best results. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of the present invention without departing from the spirit or scope of the present invention. Thus, it is proposed that the present invention covers other modifications and variations of this invention within the scope of the appended claims and their equivalents.

Claims (24)

1. CLAIMS 1. A method for manufacturing paper or cardboard, characterized in that it comprises: (a) forming a treated pulp by adding a synthetic layered silicate, a peptizer and at least one polymer, the layered silicate to a papermaking pulp; synthetic comprising a synthetic lithium magnesium hydrated sodium silicate and the at least one polymer comprising one or more members of the group consisting of cationic polymers, nonionic polymers and amphoteric polymers under cationic conditions; and (b) forming the pulp treated in the paper or cardboard.
2. 2. The method according to claim 1, characterized in that the synthetic layered silicate comprises laponite.
3. The method according to claim 1, characterized in that the synthetic layered silicate is added to the pulp in an amount of at least about 0.02 pounds (0.05 pounds) on a dry basis, per ton of pulp based on the weight of dry solids from the pulp.
4. 4. The method according to claim 1, characterized in that the synthetic layered silicate is added to the pulp-in an amount of about 0.1 kilograms (0.1 pounds) to about 2.3 kilograms (5.0 pounds) on a dry basis, by ton of pulp based on the weight of dry pulp solids.
5. 5. The method according to claim 1, characterized in that the synthetic layered silicate is added to the pulp in an amount of about 0.09 kilograms (0.2 pounds) to about 0.5 kilograms (1.0 pounds) on a dry basis, per tonne of pulp based on the weight of dry pulp solids.
6. 6. The method according to claim 1, characterized in that the peptizer comprises an inorganic polyphosphate peptizer.
7. The method according to claim 1, characterized in that the peptizer comprises tetrasodium pyrophosphate.
8. 8. The method of compliance with the claim 1, characterized in that the synthetic layered silicate is added to the pulp in the form of an aqueous dispersion and wherein the dispersion contains the inorganic polyphosphate peptizer in an amount sufficient to maintain the dispersion in the form of a sol for a period of time. default of time.
9. The method according to claim 5, characterized in that the aqueous dispersion contains the synthetic layered silicate in an amount of up to about 10% by weight.
10. 10. The method according to claim 1, characterized in that the cationic polymer is present and comprises a cationic polymer containing synthetic nitrogen.
11. 11. The method according to the claim 1, characterized in that the cationic polymer is present and comprises one or more members of the group consisting of cationic polyacrylamides and copolymers thereof; and cationic diallyldimethylammonium chloride and copolymers thereof.
12. The method according to claim 1, characterized in that the cationic polymer is present and added to the pulp in an amount of at least about .005 kilos (0.01 pounds) on a dry basis, per tonne of pulp based on the weight of dry pulp solids.
13. The method according to claim 1, characterized in that the cationic polymer is present and is added to the pulp in an amount of about .05 kilograms (0.1 pounds) to about 2.3 kilograms (5 pounds) on a dry basis, per ton of pulp based on the weight of dry pulp solids.
14. The method according to claim 1, characterized in that the cationic polymer is present and is added to the pulp in an amount approximately 0.09 kilograms (0.2 pounds) to approximately .900 kilograms (2 pounds) on a dry basis, per ton of pulp based on the weight of dry pulp solids.
15. 15. The method according to claim 1, characterized in that it further comprises applying shear stress to the pulp in one or more stages of shear stress which includes a stage of high final shear stress in which the pulp is passed through a screen before entering a headbox of a papermaking apparatus.
16. 16. The method of compliance with the claim 15, characterized in that the polymer is added to the pulp prior to the final high shear stage and wherein the synthetic layered silicate is added to the pulp after the final high shear stage.
17. The method according to claim 15, characterized in that the synthetic layered silicate is added to the pulp before the final high shear stage and where the polymer is added to the pulp after the high shear stage. final.
18. 18. A paper or cardboard, characterized in that it is made in accordance with the method of claim 1.
19. 19. A papermaking apparatus, characterized in that it comprises a supply of synthetic layered silicate, a supply of a papermaking pulp. , a device for feeding the synthetic layered silicate from the supply of the synthetic layered silicate to the supply of papermaking pulp, a supply of a holding system polymer, a device for feeding the holding system polymer from the supply of retaining polymer to the papermaking pulp, and a device for forming the pulp in a paper or cardboard after treatment with the synthetic layered silicate and the retaining system polymer, wherein the retaining system polymer is a cationic polymer, a non-ionic polymer, or an amphoteric polymer under cationic conditions, or combinations thereof and wherein the synthetic layered silicate comprises a synthetic hydrated lithium magnesium sodium silicate and is fed to the papermaking pulp in the form of an aqueous dispersion which also includes an inorganic polyphosphate peptizer.
20. The apparatus according to claim 19, characterized in that the device for forming the pulp comprises a mixing box in communication with the supply of the treated pulp, a fan pump in communication with the mixing box, a screen 'in communication with the fan pump, and a head box in communication with the screen.
21. The apparatus according to claim 20, characterized in that a supply tank is provided to contain a supply of pulp, and the communication between the supply tank and the mixing box includes a refining apparatus for refining the pulp before enter the mix box.
22. 22. The apparatus according to claim 20, characterized in that it further comprises a foamy water silo, wherein the foamed water silo has an inlet in communication with the mixing box, an inlet in communication with the headbox, and an output in communication with the fan pump.
23. 23. The apparatus according to claim 22, characterized in that it further comprises one or more refiners for refining the pulp prior to the formation of the pulp in the head box.
24. 24. A paper or cardboard, characterized in that it is made from a drained paper tape, the paper tape comprising a treated pulp, the treated pulp comprising cellulosic fibers, sodium silicate lithium magnesium hydrate, at least one polymer retention system and an inorganic polyphosphate peptizer, the retention system polymer comprising a cationic polymer, a nonionic polymer, or an amphoteric polymer under cationic conditions, or combinations thereof.