ES2201725T3 - A PROCEDURE FOR THE MANUFACTURE OF PAPER. - Google Patents

Abstract

The invention relates to a process for the production of paper from a suspension containing cellulosic fibres, and optional fillers, which comprises adding to the suspension a drainage and/or retention aid comprising a cationic organic polymer, forming and dewatering the suspension on a wire, wherein the cationic organic polymer has an aromatic group and the suspension which is dewatered on the wire has a conductivity of at least 2.0 mS/cm.

Description

A procedure for the manufacture of paper.

This invention relates to the manufacture of paper, and more specifically to a procedure for production of paper in which a cationic organic polymer is added which It has an aromatic pulp group for papermaking. The procedure provides improved drainage and retention.

Background

In the papermaking technique, it feeds an aqueous suspension containing cellulosic fibers, and optional fillers and additives, called pulp, in a head box that propels the pulp into a cloth metal shaping Water drains from the pulp to through the metal forming fabric so that it forms a wet band of paper on the wire cloth, and then water is removed and the band is dried in the drying section of the paper machine The water obtained by removing water from the paste  bin, called white water, which normally contains fine particles, for example fine fibers, fillers and additives, are Recirculates normally in the papermaking process. Coadjuvants for drainage and retention are introduced conventionally in the pulp to facilitate drainage and increase adsorption of fine particles in the fibers cellulosic so that they are retained with the fibers on the metallic cloth. They are widely used as drainage aids and retention cationic organic polymers such as cationic starch and cationic acrylamide based polymers. These polymers they can be used alone, but they are used more frequently in combination with other polymers and / or with microparticulate anionic materials such as, for example, anionic inorganic particles such as colloidal silica, colloidal silica modified with aluminum and bentonite.

U.S. Patent Documents nOS 4,980,025; 5,368,833; 5,603,805; 5,607,552; and 5,858,174; as well as International Patent Application WO 97/18351 describe the use of cationic and amphoteric acrylamide-based polymers and anionic inorganic particles as paste additives paper mill in papermaking. These additives are among the most effective drainage and retention aids in use at present. Similar systems are described in the request for European Patent No. 805,234.

It has been observed, however, that the behavior of the drainage and retention aids that comprise cationic organic polymers deteriorate when used in paper pulps with high levels of salt, that is, high conductivity, and dissolved and colloidal substances. I know normally require higher doses of cationic polymer in such paper pulps, but usually the effect of drainage and retention obtained is not entirely satisfactory yet. These problems they are notable in paper mills where he recirculates extensive white water with the introduction of only small amounts of fresh water in the procedure, therefore further increasing the accumulation of salts and materials colloidal in the white water and the pulp of which it has to remove the water

The invention

In accordance with the present invention, it has been found that improved drainage and retention can be obtained in the paper pulps containing high levels of salt (high conductivity) and colloidal materials and / or in the procedures of paper manufacturing with a high degree of water recirculation white when using a drain and retention aid that comprises a cationic organic polymer having a group aromatic. More specifically, the present invention relates to a procedure for the production of paper from a suspension containing cellulosic fibers and optional charges, which comprises adding a drainage aid to the suspension and retention comprising a cationic organic polymer, forming and remove water from the suspension on a wire net, being characterized the process because the cationic organic polymer it has an aromatic group and the suspension from which the water in the wire net has a conductivity of at least 2.0 mS / cm The present invention also relates to a process as described in the pre-characterizing clause above, the procedure also being characterized in that it comprises form and remove water from the suspension on a wire net for get a wet band that contains cellulosic fibers, or paper and white water, recirculate white water and optionally introduce fresh water to form a suspension containing cellulosic fibers and optional charges, which must be removed water to form paper, in which the cationic organic polymer It has an aromatic group, and the amount of fresh water introduced is less than 30 tons per ton of dry paper produced. The invention, therefore, relates to a process such as It is further defined in the claims.

The present invention results in a drain and / or improved retention when using paper pulps that they have high salt contents, and therefore they have high conductivity levels and colloidal materials. The present invention also results in drainage and / or retention improved when applied to manufacturing procedures for paper with extensive white water recirculation and supply of New limited contribution water and / or procedures that use water of new contribution that has high salt content, in particular salts of di- and multivalent cations such as calcium. From In this way, the present invention makes it possible to increase the speed of the paper machine and use lower doses of additives to provide a similar drainage and / or retention effect, leading therefore to a papermaking process Improved and economic benefits.

\hbox{-C _{6} H _{3} -,}

y -C_{6}H_{2}-, por ejemplo, en forma de fenileno (-C_{6}H_{4}), xilileno (-CH_{2}-C_{6}H_{4}-CH_{2}-), fenilo (-C_{6}H_{5}), bencilo (-CH_{2}-C_{6}H_{5}), fenetilo (-CH_{2}CH_{2}-C_{6}H_{5}) y fenilo sustituido (por ejemplo -C_{6}H_{4}-Y, -C_{6}H_{3}Y_{2} y -C_{6}H_{2}Y_{3}), en el que pueden seleccionarse uno o más sustituyentes (Y) unidos al anillo fenilo a partir de hidroxilo, haluros, por ejemplo cloruro, nitro, y grupos hidrocarbonados que tienen de 1 a 4 átomos de carbono.The cationic organic polymer containing an aromatic group according to this invention, also referred to herein as "main polymer", is capable of functioning as a drainage and retention aid (agent). The term "drainage and retention aid", as used herein, refers to one or more components (adjuvants, agents or additives), which, when added to a pulp, provide better drainage and / or retention than which are obtained when said component or components are not added. Accordingly, the main polymer provides improved drainage and / or retention, either when used alone or when used together with one or more additional paper pulp additives. The main polymer can be linear, branched or crosslinked, for example, in the form of a microparticulate material. The main polymer is preferably water soluble or water dispersible. The aromatic group of the main polymer may be present in the main chain or, preferably, it may be a pendant group attached or extending from the main chain of the polymer or present in a pendant group that is attached or extending from the chain main polymer. Suitable aromatic (aryl) groups include those comprising an optionally substituted phenyl group, an optionally substituted phenylene group and an optionally substituted naphthyl group, for example groups having the general formula -C 6 H 5, -C 6 H 4 -,

 ? {-C6H3-,} 

and -C 6 H 2 -, for example, in the form of phenylene (-C 6 H 4), xylylene (-CH 2 -C 6 H 4 -CH_ { 2} -), phenyl (-C 6 H 5), benzyl (-CH 2 -C 6 H 5), phenethyl (-CH 2 CH 2 -C_ { 6} H 5) and substituted phenyl (for example -C 6 H 4 -Y, -C 6 H 3 Y 2 and -C 6 H 2 Y 2) 3}), in which one or more substituents (Y) attached to the phenyl ring can be selected from hydroxyl, halides, for example chloride, nitro, and hydrocarbon groups having 1 to 4 carbon atoms.

The main polymer can be selected from homopolymers and copolymers prepared from one or more monomers comprising at least one monomer having a group aromatic, an ethylenically unsaturated monomer so suitable, and the main polymer is suitably a polymer of vinyl addition The term "vinyl addition polymer", as used herein, refers to a polymer prepared by the polymerization by the addition of one or more vinyl monomers or ethylenically unsaturated monomers that include, for example, acrylamide-based and acrylate-based monomers. The Suitable major polymers include addition polymers of cationic vinyl obtained by polymerizing a cationic monomer or a mixture of monomers containing a cationic monomer represented by the general formula (I):

\uelm{C}{\uelm{\para}{\hskip-0.8cmCH _{2} =C---R _{1} }}

---A_{1}---B_{1}---

\melm{\delm{\para}{R _{3} }}{N ^{+} }{\uelm{\para}{R _{2} }}

---Q

\hskip0.5cm

X^{-}(I) O =

 \ uelm {C} {\ uelm {\ para} {\ hskip-0.8cmCH2 = C --- R1}} 

--- A_ {1} --- B_ {1} ---

 \ melm {\ delm {\ para} {R 3}} {N ^ {}} {\ uelm {\ para} {R 2}} 

--- Q

 \ hskip0.5cm 

X -

wherein R 1 is H or CH 3; R2 and R 3 are each or, preferably, an alkyl group having 1 to 3 carbon atoms, usually 1 to 2 carbon atoms; A 1 is O or NH; B1 is an alkylene group having from 2 to 8 carbon atoms, suitably from 2 to 4 carbon atoms, or a hydroxypropylene group; Q is a substituent that contains a group aromatic, suitably a phenyl group or a phenyl group substituted, which can be attached to nitrogen through a group alkylene that normally has 1 to 3 carbon atoms, suitably 1 to 2 carbon atoms, and preferably Q is a benzyl group (-CH 2 -C 6 H 5); and X- is an anionic counterion, usually a halide such as chloride. Examples of suitable monomers represented by the general formula (I) include quaternary monomers obtained by treating (meth) dialkylaminoalkyl acrylates, for example, (meth) dimethylaminoethyl acrylate, (meth) acrylate diethylaminoethyl and (meth) acrylate dimethylaminohydroxypropyl, and (meth) acrylamides of dialkylaminoalkyl, for example (meth) acrylamide of dimethylaminoethyl, diethylaminoethyl (meth) acrylamide, (meth) dimethylaminopropyl acrylamide and (meth) diethylaminopropyl acrylamide, with benzyl Preferred cationic monomers of general formula (I) include quaternary salt of benzyl chloride and acrylate of dimethylaminoethyl and quaternary salt of benzyl chloride and methacrylate dimethylaminoethyl.

The main polymer can be a homopolymer prepared from a cationic monomer that has a group aromatic or a copolymer prepared from a mixture of monomers comprising a cationic monomer having a group aromatic and one or more copolymerizable monomers. The monomers do not Suitable copolymerizable ionics include monomers represented. by the general formula (II):

\uelm{C}{\uelm{\para}{\hskip-0.8cmCH _{2} =C---R _{4} }}

---A_{2}---B_{2}---

\melm{\delm{\para}{R _{6} }}{N}{\uelm{\para}{R _{5} }}

(II) O =

 \ uelm {C} {\ uelm {\ para} {\ hskip-0.8cmCH2 = C --- R4}} 

--- A_ {2} --- B_ {2} ---

 \ melm {\ delm {\ para} {R6}} {N} {\ uelm {\ para} {R5}}} 

wherein R 4 is H or CH 3; R 5 and R 6 are each H or a hydrocarbon group, suitably alkyl, which is 1 to 6, suitably 1 to 4 and usually from 1 to 2 carbon atoms; A2 is O or NH; B_ {2} is a group alkylene of 2 to 8 carbon atoms, suitably of 2 to 4 atoms of carbon, or a hydroxypropylene group or, alternatively, A and B they are both nothing, where there is a simple link between C and N (O = C-NR5R6). Examples of monomers Suitable copolymers of this type include (meth) acrylamide, acrylamide based monomers such as (meth) N-alkyl acrylamides and (meth) acrylamides of N, N-dialkyl, by example, N, n-propylacrylamide, N-Isopropyl (meth) acrylamide, (meth) N, n-butyl acrylamide, (meth) N-isobutyl acrylamide and N, t-butyl (meth) acrylamide; Y (meth) dialkylaminoalkyl acrylamides, for example dimethylaminoethyl (meth) acrylamide, (meth) acrylamide of diethylaminoethyl, dimethylaminopropyl (meth) acrylamide and diethylaminopropyl (meth) acrylamide; monomers based on acrylate as (meth) dialkylaminoalkyl acrylates, by example, (meth) dimethylaminoethyl acrylate, (meth) diethylaminoethyl acrylate, (meth) acrylate t-butylaminoethyl and acrylate dimethylaminohydroxypropyl; and vinylamides, for example, N-vinylformamide and N-vinyl acetamide. Preferred non-ionic copolymerizable monomers include acrylamide and methacrylamide, that is, (meth) acrylamide, and the main polymer is preferably a polymer based on acrylamide

The copolymerizable cationic monomers Suitable include the monomers represented by the formula general (III):

\uelm{C}{\uelm{\para}{\hskip-0.8cmCH _{2} =C---R _{7} }}

---A_{3}---B_{3}---

\melm{\delm{\para}{R _{9} }}{N ^{+} }{\uelm{\para}{R _{8} }}

---R_{10}

\hskip0.5cm

X^{-}(III) O =

 \ uelm {C} {\ uelm {\ para} {\ hskip-0.8cmCH2 = C --- R7}} 

--- A_ {3} --- B_ {3} ---

 \ melm {\ delm {\ para} {R 9}} {N ^ {}} {\ uelm {\ para} {R 8}}} 

--- R_ {10}

 \ hskip0.5cm 

X -

wherein R 7 is H or CH 3; R_ {8}, R 9 and R 10 are each H or, preferably, a group hydrocarbon, suitably alkyl, having 1 to 3 atoms of carbon, suitably 1 to 2 carbon atoms; A_ {3} is O or NH; B 3 is an alkylene group of 2 to 4 carbon atoms, suitably from 2 to 4 carbon atoms, or a group hydroxypropylene, and X - is an anionic counterion, usually Methylsulfate or a halide such as chloride. Examples of monomers Suitable copolymerizable cationics include addition salts of acids and quaternary ammonium salts of the (meth) acrylates of dialkylaminoalkyl and (meth) acrylamides of dialkylaminoalkyl mentioned above, normally prepared using acids such as HCl, H 2 SO 4, etc., or agents quaternizers such as methyl chloride, dimethyl sulfate, etc .; Y diallyldimethylammonium chloride. Cationic monomers Preferred copolymers include quaternary salt of methyl and (meth) dimethylaminoethyl acrylate and chloride diallyldimethylammonium. The monomers can also be used copolymerizable anionics such as acrylic acid, methacrylic acid, various sulfonated vinyl addition monomers, etc. Y, preferably in minors quantities.

According to this invention the main polymer it can be prepared from a mixture of monomers comprising generally 1 to 99% in moles, suitably 2 to 50% in moles, and preferably 5 to 20 mole% of cationic monomer having an aromatic group, preferably represented by the general formula (I), and 99 to 1 mol%, suitably 98 at 50 mol%, and preferably 95 to 80 mol% of others copolymerizable monomers preferably comprising acrylamide or methacrylamide ((meth) acrylamide), comprising the mixture of  suitably monomers of 98 to 50 mol% and preferably of 95 to 80 mol% of (meth) acrylamide, the sum of percentages equal to 100.

The main polymer can also be selected from polymers prepared by a reaction of condensation of one or more monomers containing a group aromatic. Examples of such monomers include diisocyanates of toluene, bisphenol A, phthalic acid, phthalic anhydride, etc., which can be used in the preparation of cationic polyurethanes, cationic polyamidaamines, etc.

Alternatively or additionally, the polymer main may be a polymer undergoing aromatic modification using an agent that contains an aromatic group. The agents Suitable modifiers of this type include benzyl chloride, benzyl bromide, chloride N- (3-Chloro-2-hydroxypropyl) -N-benzyl-N, N-dimethylammonium, and chloride N- (3-Chloro-2-hydroxypropyl) pyridinium Suitable polymers for such aromatic modification include vinyl addition polymers. If the polymer contains a tertiary nitrogen that can be made quaternary by the agent of modification, the use of such agents normally gives as result in which the polymer becomes cationic. Alternatively, the polymer to be modified. aromatic can be cationic, for example, an addition polymer Cationic vinyl.

The charge density of the main polymer is normally within the range of 0.1 to 6.0 meqv / g of polymer dry, suitably 0.2 to 4.0 and preferably 0.5 to 3.0.

The weight average molecular weight of the polymers synthetic main synthetic is generally at least approximately 500,000, adequately greater than approximately 1,000,000, and preferably greater than about 2,000,000. The upper limit is not critical; can be approximately 50,000,000, usually 30,000,000 and adequately of 25,000,000

The main polymer of this invention may be in any state of aggregation such as, for example, in form solid, for example powders, in liquid form, for example solutions, emulsions, dispersions, including dispersions of salts, etc. Examples of main polymers suitable for use in this invention include those described in the patent documents from the U.S. No. 5,169,540; 5,708,071; and the requests of European patent 183,466, 525,751 and 805,234. When you add to the pulp, the main polymer is properly shaped liquid, for example in the form of solution or dispersion aqueous.

       \ newpage
    

The main polymer can be added to the paper pulp from which water has to be removed in quantities which may vary within wide limits depending on, between other, type of pulp, salt content, type of salts, content of loads, type of load, point of addition, etc. The main polymer is generally added in an amount such that provides better retention than what you get when you don't add. The main polymer is usually added in a amount of at least 0.001%, often at least 0.005% in that, based on dry substance of pulp while the limit higher is normally 3% and adequately 1.5% in weight.

In a preferred embodiment of this invention, the main polymer is used together with an additional paste additive bin, thus forming a drainage and retention aid that It comprises two or more components, usually referred to as drainage and retention aids. The term "adjuvants of drainage and retention ", as used herein, refers to to two or more components (adjuvants, agents or additives), the which, when added to the pulp, provide better drainage and / or retention than that obtained when not added the components. Examples of additives suitable for pulp of this type include microparticulate anionic materials, by example anionic organic particles and inorganic particles anionic, soluble anionic vinyl addition polymers in water, cationic organic polymers of low molecular weight, Aluminum compounds and their combinations. In a preferred aspect of this embodiment, the main polymer is used together with a microparticulate anionic material, notably with particles anionic inorganic In another preferred aspect of this embodiment, the main polymer is used together with particles anionic inorganic and a low weight cationic organic polymer molecular. In yet another preferred aspect of this embodiment, The main polymer is used together with inorganic particles anionic and an aluminum compound.

The anionic inorganic particles that can used according to the invention include anionic particles based on silica and smectite clays. It is preferred that anionic inorganic particles are in the size range of colloidal particles. Particles are preferably used anionic based on silica, that is, particles based on SiO2 or silicic acid, and such particles are supplied generally in the form of colloidal aqueous dispersions, called Suns. Examples of suitable silica based particles include colloidal silica and different types of polysilicic acid. The suns silica based can also be modified and contain other elements, for example aluminum and / or boron, that may be present in the aqueous phase and / or the silica based particles. The Suitable silica based particles of this type include silica colloidal modified with aluminum and aluminum silicates. Can be also use mixtures of such suitable particles based on silica. The drainage and retention aids that comprise suitable anionic particles based on silica are described in U.S. patent documents No. 4,388,150, 4,927,498, 4,954,220, 4,961,825, 4,980,025, 5,127,994, 5,176,891, 5,368,833, 5,447,604, 5,470,435, 5,543,014, 5,571,494, 5,573,674, 5,584,966, 5,603,805, 5,688,482 and 5,707,493.

Anionic silica-based particles have suitably an average particle size smaller than about 50 nm, preferably less than about 20 nm and more preferably in the range of about 1 to approximately 10 nm. As is conventional in the chemistry of the silica, particle size refers to the average size of the primary particles, which may be aggregated or not aggregated. The specific surface of silica-based particles suitably it is greater than 50 m 2 / g and preferably greater than 100 m2 / g. Generally, the specific surface may be up to about 1700 m 2 / g and preferably up to 1000 m 2 / g. The specific surface can be measured by titration with NaOH in a known manner, for example as described by Sears in Analytical Chemistry 28 (1956): 12, 1981-1983 and in the U.S. patent document No. 5,176,891. The area provided thus represents the surface specific mean of the particles.

In a preferred embodiment of the invention, the anionic inorganic particles are silica based particles that have a specific surface within the range of 50 to 1000 m 2 / g, preferably 100 to 950 m 2 / g. The suns of the silica-based particles of these types also encompass modified soles such as silica-based soles that contain aluminum and silica-based suns containing boron. The silica-based particles are preferably present in a sun that has an S value in the range of 8 to 45%, preferably from 10 to 30%, which contains particles based on silica with a specific surface in the range of 300 to 1000 m 2 / g, suitably from 500 to 950 m 2 / g, and preferably from 750 to 950 m2 / g, whose suns can be modified with aluminum and / or boron, as mentioned above. For example, the particles can be modified superficially with aluminum until a degree of substitution of silicon atoms of 2 to 25%. The value S can be measured and calculated as described by Iler & Dalton in J. Phys. Chem. 60 (1956), 955-957. The S value indicates the degree of aggregation or microgel formation, and a lower S value indicates a higher degree of aggregation.

Still in another preferred embodiment of invention, silica based particles are selected from of polysilicic acid and modified polysilicic acid having a high specific surface area, adequately larger than approximately 1000 m 2 / g. The specific surface can be within the range of 1000 to 1700 m 2 / g and preferably from 1050 to 1600 m2 / g. Acid soles modified polysilic may contain other elements, for example aluminum and / or boron, which may be present in the phase aqueous and / or silica based particles. In the technique, the Polysilicic acid is also called polymeric silicic acid, polysilicic acid, polysilicate and microgel microgel of polysilicate, all of which are encompassed by the term acid polysilicic used herein. The compounds that contain aluminum of this type is usually also called polyaluminosilicate and polyaluminosilicate microgel, which covered with the terms colloidal silica modified with aluminum and aluminum silicate used herein.

Clays of the type are known in the art smectite that can be used in the process of the invention and include natural forms, synthetic and treated materials chemically Examples of suitable smectite clays include Montmorillonite / Bentonite, Hectorite, Beidelite, Nontronite and saponite, preferably bentonite, and especially bentonite which after swelling preferably has a surface specific from 400 to 800 m2 / g. The appropriate clays are described in U.S. patent documents nOS 4,753,710, 5,071,512 and 5,607,552.

Anionic organic particles that can used according to the invention include addition polymers of highly crosslinked anionic vinyl, suitable copolymers that they comprise an anionic monomer such as acrylic acid, acid methacrylic and sulfonated vinyl addition monomers or phosphonates, usually copolymerized with non-ionic monomers such as (meth) acrylamide, (meth) alkyl acrylates, etc. Useful anionic organic particles also include anionic condensation polymers, for example acid soles melaminosulfonic. Anionic Vinyl Addition Polymers water soluble that can be used according to the invention include copolymers comprising an anionic monomer such as the Acrylic acid, methacrylic acid and vinyl addition monomers sulfonated, usually copolymerized with non-ionic monomers such as acrylamide, alkyl acrylates, etc., for example described in U.S. patent documents nOS 5,098,520 and 5,185,062.

Low weight cationic organic polymers molecular (from now on LMW) that can be used according with the invention include those that are commonly referred to and used as anionic waste collectors (ATC). The ATC are known in the technique as neutralizing and / or fixing agents for harmful anionic substances present in the pulp and its use in combination with drainage and / or retention aids often provides additional improvement to drainage and / or retention. LMW cationic organic polymer can be derived from sources natural or synthetic, and preferably is a synthetic polymer LMW Suitable organic polymers of this type include highly charged cationic organic LMW polymers such as polyamines, polyamidoamines, polyethyleneimines, homo- and copolymers based on diallyldimethylammonium chloride, (meth) acrylamides and (met) acrylates. In relation to the molecular weight of main polymer, the molecular weight of the organic polymer LMW cationic is preferably lower, is suitably at minus 2,000 and preferably at least 10,000. The limit higher molecular weight is usually about 700,000, suitably approximately 500,000 and usually of approximately 200,000.

The aluminum compounds that can be used from according to the invention include alum, aluminates, chloride aluminum, aluminum nitrate and polyaluminium compounds, such as poly (aluminum chlorides), poly (sulfates of aluminum), polyaluminium compounds that contain both ions chloride such as sulfate, poly (aluminum silicate sulfates) and their mixtures Polyaluminium compounds may also contain other anions other than chloride ions, for example anions of sulfuric acid, phosphoric acid, organic acids such as citric acid and oxalic acid.

The components of drainage aids and retention according to the invention can be added to the paste trash can in conventional manner and in any order. When use drainage and retention aids comprising a polymer main and an anionic microparticulate material, particles remarkably anionic inorganic, it is preferred to add the main polymer to the pulp before adding the microparticulate material, even if it can be added in the order contrary. It is further preferred to add the main polymer before of a shear stage, which can be selected between pumping, mixing, cleaning, etc., and adding the anionic particles afterwards of that shear stage. When an organic polymer is used LMW cationic or an aluminum compound, such components are preferably introduced into the pulp before introducing the main polymer, optionally used together with a material anionic microparticulate. Alternatively, the organic polymer LMW cationic and the main polymer can be introduced into the paper pulp simultaneously essentially, either separately or mixed, for example as described in the patent document from the U.S. No. 5,858,174. The LMW cationic organic polymer and the Main polymer are preferably introduced into the paste bin before inserting a microparticulate material anionic

The drainage aid (s) and retention according to the invention can be added to the paste wastebasket from which water must be removed in quantities that may vary within wide limits depending on, among others, the type and number of components, type of pulp, content of salt, type of salts, content of loads, type of load, point of addition, degree of recirculation of white water, etc. The adjuvant (s) are generally added in amounts that provide better drainage and / or retention than which are obtained when the components are not added. Polymer principal is usually added in an amount of at least 0.001%, often at least 0.005% by weight, based on substance dry pulp, and the upper limit is normally 3% and suitably 1.5% by weight. Similar amounts are suitable for water soluble anionic vinyl addition polymers, if are used. When an anionic microparticulate material is used in the procedure, the total amount added is generally at less than 0.001% by weight, often at least 0.005% by weight, based on dry substance of pulp, and the upper limit is generally 1.0% and suitably 0.6% by weight. When use silica-based anionic particles, the total amount added is adequately in the range of 0.005 to 0.5% in weight, calculated as SiO2 and based on dry paste substance bin, preferably within the range of 0.01 to 0.2% in weight. When an LMW cationic organic polymer is used in the procedure, can be added in an amount of at least 0.05%, based on dry substance of pulp from which remove the water Suitably, the amount is in the range of 0.07 to 0.5%, preferably in the range of 0.1 to 0.35%. When an aluminum compound is used in the process, the amount total introduced in the pulp from which it is to be removed water depends on the type of aluminum compound used and others desired effects of him. It is well known for example in the art use aluminum compounds as precipitators for agents formed based on rosin. The total amount added is generally at least 0.05%, calculated as Al 2 O 3 and based on dry substance of pulp. Properly the amount is in the range of 0.5 to 3.0%, preferably in the range of 0.1 to 2.0%.

The process of this invention is used. preferably in the manufacture of paper from a suspension containing cellulose fibers and optional fillers, is that is, a pulp that has a high conductivity. Normally, the conductivity of the pulp from which Eliminates water in the wire netting is at least 2.0 mS / cm, suitably at least 3.5 mS / cm, preferably at least 5.0 mS / cm and more preferably at least 7.5 mS / cm. The conductivity can be measured by standard equipment such as, for example, a WTW LF 539 instrument supplied by Christian Berner The values referred to above are determined adequately measuring the conductivity of the suspension cellulose that feeds on or is present in the head box of the paper machine or, alternatively, measuring the white water conductivity obtained by removing water from the suspension. High levels of conductivity mean high contents of salts (electrolytes), of which various salts they can be based on mono-, di- and multivalent cations such as alkali metals, for example Na + and K +, alkaline earth metals, for example Ca 2+ and Mg 2+, aluminum ions, for example Al 3+, Al (OH) 2+ and polyaluminium ions, and mono-, di- and multivalent anions such as halides, for example Cl <->, sulfates, for example SO4 <2> and HSO4 <->, carbonates, for example CO 3 2- and HCO 3 -, silicates and lower organic acids. The invention is particularly useful in the manufacture of paper from pasta bins that have high contents of di- and cation salt salts multivalent, and generally the content of di- and cations Multivalent is at least 200 ppm, suitably at least 300 ppm and preferably at least 400 ppm. The salts can derive from the preparation stage of the pulp, is that is, from materials used to form the pulp, for example water, cellulosic fibers and fillers, particularly in integrated paper mills in which a fiber suspension aqueous, concentrated from the pulp of the paper mill is mix normally with water to form a diluted suspension Suitable for papermaking in the paper mill. The Salt can also be derived from various additives introduced into the paper pulp, from the fresh water supplied to the procedure, etc. In addition, the content of salts generally it is higher in the procedures in which it is recirculated extensively white water, which can lead to a considerable accumulation of salts in the water that circulates in the process.

The present invention further encompasses papermaking procedures in which white water (recycled) is recirculated extensively that is, with a high degree of recirculation of white water, for example in which use 0 to 30 tons of fresh water per ton of dry paper produced, usually less than 20, properly less than 15, preferably less than 10 and notably less than 5 tons of fresh water per ton of paper. The recirculation of the white water obtained in the process comprises properly mix white water with cellulosic fibers and / or optional loads to form a suspension that is to be remove water; preferably comprises mixing white water with a suspension containing cellulosic fibers, and charges optional, before the suspension enters the wire net of conformation to eliminate water. White water can be mixed with the suspension before, between, simultaneously or after introduce the auxiliary drainage and retention components, if are used; and before, simultaneously or after entering the main polymer New water can be introduced in the procedure at any stage; for example, you can mix with cellulosic fibers to form a suspension, you can mix with a suspension containing cellulosic fibers to dilute and thus form the suspension from which the water, before, simultaneously or after mixing the pulp with white water and before, between, simultaneously or after introduce drain and retention aids, if used; Y before, simultaneously or after introducing the polymer principal.

Of course, additional additives can be used which are conventional in papermaking in combination with the additive (s) according to the invention, such as, for example, dry reinforcing agents, agents wet reinforcers, optical agents that provide shine, dyes, sizing agents such as sizing agents based on rosin and sizing agents that react with cellulose, for example cetene dimers and succinic anhydrides, etc. The cellulosic suspension or pulp can contain also mineral charges of conventional types such as, for example, kaolin, titanium dioxide, plaster, talc and carbonates of natural or synthetic calcium such as gypsum, powdered marbles and precipitated calcium carbonate.

The process of this invention is used for the paper production The term "paper" as used in this document of course includes not only paper and the production of same but also other sheets containing cellulose fiber or band type products, such as for example iron and cardboard, and their production. The procedure can be used in the production of paper from different types of suspensions containing cellulose fibers and suspensions should contain suitably at least 25% by weight and preferably at least 50% by weight of such fibers, based on dry substance. The suspension it can be based on fibers from chemical pulp, such as pulp sulfate, sulphite and organic solvents, mechanical pulp such as thermomechanical paste, chemical thermomechanical paste, refining and defibrator paste, both hardwood and conifers, and may also be based on recycled fibers, optionally from pastes destined, and mixtures of same.

The invention is further illustrated in the following examples, which, however, are not intended to Limit it. Parts and% refer to parts by weight and % by weight, respectively, unless another is established thing.

Example 1 (Comparison)

Drainage behavior was assessed by a Dynamic Drainage Analyzer (DDA), available from Akribi, Sweden, which measures the time to drain a given volume of pasta bin through a wire cloth when a plug is removed and vacuum is applied on the side of the wire net opposite to the side on that the pulp is present.

The supply used was based on 70% on bleached birch / pine sulfate paste weight (60/40) grade 200ºCSF refining and 30% by weight of powdered marbles. The volume of pulp was 800 ml, the consistency of 0.3% and the pH of approximately 8.

The conductivity of the pulp was adjusted to 0.47 mS / cm by the addition of sodium sulfate. Pasta wastebasket was drained in a regulated flow vessel to a 1500 rpm speed throughout the test and the chemical additions as follows: i) add polymer cationic to pulp and then drain for 30 seconds, ii) add anionic inorganic particles to the paste wastebasket and then drain for 15 seconds iii) drain the paste trash can and automatically record the time of sewer system.

The polymers used in the test series were P1) a cationic copolymer prepared by polymerization of acrylamide (90 mol%) and chloride acryloxyethyldimethylbenzylammonium (10 mol%) and having a weight average molecular weight of approximately 6,000,000; and P2) a copolymer cationic prepared by acrylamide polymerization (90% in moles) and acryloxyethyltrimethylammonium chloride (10 mol%), and which has an average molecular weight of approximately 6,000,000. The polymers P1 and P2 were dissolved in water and used as 0.1% aqueous solutions.

The anionic inorganic particles used were silica-based particles of the type described in the document of U.S. Patent No. 5,368,833. The sun had an S value of approximately 25% and contained silica particles with a specific surface area of approximately 900 m {2} / g that is superficially modified with aluminum to a degree of 5%. Silica-based particles were added in an amount of 1.0 kg / t, calculated as SiO2 and based on dry paste system paper bin.

Table 1 shows the drain time a various doses of P1 and P2, calculated as dry polymer in the dry pulp system.

TABLE 1

Test number Dose of polymer SiO_2 dose Conductivity Time of elimination [kg / t] [kg / t] [mS / cm] of water [s] P1 P2 one 0 0 0.47 18.4 18.4 two one one 0.47 12.5 10.6 3 1.5 one 0.47 6.9 5.6 4 two one 0.47 4.9 4.3

Example 2 (Comparison)

The effect of water removal was evaluated and retention by the DDA used in example 1 in combination With a nephelometer. The first retention step was evaluated by measuring the turbidity of the filtrate, the white water, obtained by draining the paper pulp

The supply used was based on 56% by weight TMP / SGW (80/20) peroxide bleached paste, 14% by weight of bleached birch / pine sulfate paste (60/40) with grade 200 ° C refining and 30% by weight of kaolin. It was added to the pasta bin 40 g / l of a colloidal fraction, bleaching water of one SC paper mill, filtered through a 5 µm sieve and concentrated with a UF filter, which allows up to 200,000 passage. The Pulp volume was 800 ml, the consistency of 0.14% and the pH was adjusted to 4.0 using dilute sulfuric acid. The conductivity was adjusted by adding calcium chloride (60 ppm Ca 2+), magnesium sulfate (18 ppm Mg 2+) and sodium bicarbonate (134 ppm HCO 3 -).

Polymers and inorganic particles anionics according to example 1 were similarly used in This series of essays. Two doses of polymers, 1 kg / t and 2 were used kg / t, respectively, calculated as dry polymer in the system Dry of pulp. Table 2 shows the effect of the water removal and retention at various doses of particles based on silica, calculated as SiO_ {2} and based on the system Dry of pulp.

TABLE 2

No. of Dose of Dose from Conductivity Elimination time Turbidity test polymer [kg / t] SiO_ {2} [kg / t] [mS / cm] of water [s] [NTU] P1 P2 P1 P2 one one 0 1,375 21.2 18.7 63 55 two one one 1,375 17.2 16.1 67 60 3 one two 1,375 21.2 18.6 66 57 4 two 0 1,375 15.2 14.2 47 Four. Five 5 two one 1,375 eleven 9.9 47 47 6 two two 1,375 11.4 10.8 Four. Five fifty

Example 3

In this series of trials, the effect of water removal and retention according to the procedure described in example 2.

The supply used was the same as that used in Example 2. The volume of pulp was 800 ml and the pH approximately 7. Conductivity was adjusted by adding of calcium chloride, thus simulating a content of very high electrolytes and a high degree of recirculation of White water.

Polymers and anionic inorganic particles according to example 1 they were used similarly in this series of essays.

Table 3 shows the elimination effect of water and retention at various doses of silica-based particles, calculated as SiO2 and based on the dry pasta system paper bin.

TABLE 3

No. of Dose of Dose from Conductivity Elimination time Turbidity test polymer [kg / t] SiO_ {2} [kg / t] [mS / cm] of water [s] [NTU] P1 P2 P1 P2 990 ppm Ca 2+ one two 0 5.5 14.2 19.2 42 64 two two one 5.5 10.8 13.9 41 43 3 two two 5.5 7.7 9.5 35 36 4 two 3 5.5 7.3 8.9 32 39 1300 ppm Ca 2+ 5 two 0 7.0 16.2 23.0 46 fifty 6 two one 7.0 10.0 17.1 40 Four. Five 7 two two 7.0 7.5 13.6 36 44 8 two 3 7.0 7.7 11.7 3. 4 44 1930 ppm Ca 2+ 9 two 0 10.0 18.7 22.0 44 58 10 two one 10.0 11.6 23.3 39 52 eleven two two 10.0 8.2 15.8 36 53 12 two 3 10.0 8.0 15.4 41 47

Example 4

In these test series, the effect of water removal with a "Canadian Standard Freeness Tester ", which is the conventional method for characterization of drainage according to SCAN-C 21:65. All Chemical additions were made in a "Britt Dynamic Drainage Jar "with the output blocked at a speed of 1000 rpm stirring for 45 seconds according to the procedure of example 1 and the pulp system then was transferred to the Freeness device. Here the hole was blocked more small at the bottom of the Freeness meter and the time to filter the 400 ml of supply through the sieve. The pulp was taken from a closed circuit paper mill using waste paper. The consistency was 0.14%, the conductivity of 8.0 mS / cm and the pH of approximately 7. Table 4 shows the effect of water removal at various doses of silica-based particles, calculated as SiO2 and based on the dry pulp system.

TABLE 4

Test number Dose of polymer SiO_2 dose Conductivity Time of elimination [kg / t] [kg / t] [mS / cm] of water [s] P1 P2 one 0.6 0 8.0 100.4 103.2 two 0.6 0.25 8.0 66.4 92.5 3 0.6 0.5 8.0 58.3 85.8 4 0.6 0.75 8.0 50.0 76.0 5 0.6 one 8.0 44.6 79.2

Example 5

In this series of trials, the effect of water removal as in example 3, except that it was used both sodium acetate (550 ppm Na +) and calcium chloride (1300 ppm Ca 2+) to adjust the conductivity.

In this series of tests they were used similar polymers and anionic inorganic particles according to the Example 1.

Table 5 shows the elimination effect of water at various doses of silica-based particles, calculated as SiO_ {2} and based on dry pulp system.

TABLE 5

Test number Dose of polymer SiO_2 dose Conductivity Time of elimination [kg / t] [kg / t] [mS / cm] of water [s] P1 P2 one two one 2.5 16.1 18.2 two one 3 10.0 10.7 14.7 3 two 3 10.0 6.8 13.5 4 3 3 10.0 5.3 14.0 5 two one 10.0 9.7 20.4 6 two two 10.0 7.9 14.8

Example 6

In this series of trials the effect of water removal and retention as in example 3, using a combination of sodium acetate (550 ppm Na +) and chloride calcium (1300 ppm Ca2 +) to adjust the conductivity.

In this series of tests the polymers were used according to example 1 similarly. The microparticulate material used anionic was a hydrated suspension of Na-bentonite powder in water. The bentonite had a surface charge of approximately 0.33 meq / g and capacity to swell 41 ml (2g). Bentonite particles are added in an amount of 8.0 kg / t, calculated as bentonite Dry in the dry pulp system.

Table 6 shows the elimination effect of water and retention at various doses of P1 and P2, calculated as Dry polymer in a dry pulp system.

TABLE 6

No. of Dose of Dose from Conductivity Elimination time Turbidity test polymer [kg / t] SiO_ {2} [kg / t] [mS / cm] of water [s] [NTU] P1 P2 P1 P2 one one 8 10.0 13.6 18.5 41 47 two two 8 10.0 10.8 20.6 29 41 3 3 8 10.0 8.48 24.8 twenty 36 4 4 8 10.0 7.42 26.6 18 36

Example 7

In this series of trials the effect of water removal as in example 6, except that it was used sodium chloride to adjust conductivity.

In this series of tests the polymers were used and bentonite according to example 6 in a similar way. Particles of Bentonite were added in an amount of 8.0 kg / t, calculated like dried bentonite in a dry pulp system. Table 7  shows the effect of water removal and retention to various dose of P1 and P2, calculated as dry polymer in the dry system of pulp

TABLE 7

Test number Dose of polymer SiO_2 dose Conductivity Time of elimination [kg / t] [kg / t] [mS / cm] of water [s] P1 P2 550 ppm Na + one two 8 2.5 15.3 17.5 two 3 8 2.5 11.9 14.1 3 4 8 2.5 8.6 9.8 4 5 8 2.5 6.8 8.2 3320 ppm Na + 5 two 8 10.0 12.7 15.5 6 3 8 10.0 9.4 12.5 7 4 8 10.0 6.9 10.9 8 5 8 10.0 5.6 10.0

Example 8

In this series of trials the effect of water removal as in example 3 except chloride was used of zinc to adjust the conductivity. In this series of essays they used inorganic anionic polymers and particles according to the Example 1 similarly.

Table 8 shows the test results. water removal at various doses of particles based on silica, calculated as SiO2 and based on a dry system of paper pulp

TABLE 8

Test number Dose of polymer SiO_2 dose Conductivity Time of elimination [kg / t] [kg / t] [mS / cm] of water [s] P1 P2 700 ppm Zn 2+ one two 0 2.4 13.6 22.7 two two one 2.4 7.9 8.5 3 two two 2.4 5.5 5.6 1400 ppm Zn 2+ 4 two 0 4,5 18.0 28.0 5 two two 4,5 6.3 11.4

Claims (16)

1. A process for the production of paper from a suspension containing cellulosic fibers and optional fillers, comprising adding to the suspension a drainage and retention aid comprising a cationic organic polymer, forming and removing water from the suspension in a metallic fabric, characterized in that the cationic organic polymer has an aromatic group and because the suspension from which the water in the metallic fabric is removed has a conductivity of at least 2.0 mS / cm. 2. A method according to claim 1, characterized in that the suspension from which the water in the metallic fabric is removed has a conductivity of at least 5.0 mS / cm. 3. A method according to claim 1 or 2, characterized in that the method further comprises removing the water from the suspension in a metal cloth to obtain a wet paper and white water band, recirculating the white water and introducing fresh water. to form a suspension containing cellulosic fibers and optional charges, from which the water has to be removed, the amount of newly introduced water being less than 20 tons per ton of dry paper produced. 4. A method according to claim 1, 2 or 3, characterized in that less than 10 tons of fresh water are introduced per ton of dry paper produced. 5. A process according to any of the preceding claims, characterized in that the cationic organic polymer is a vinyl addition polymer comprising in polymerized form one or more monomers comprising at least one monomer having an aromatic group. 6. A process according to any of the preceding claims, characterized in that the cationic organic polymer is an acrylamide based polymer. 7. A process according to any of the preceding claims, characterized in that the cationic organic polymer polymerically comprises a cationic monomer having an aromatic group represented by the general formula (I): (I) O =

 \ uelm {C} {\ uelm {\ para} {\ hskip-0.8cmCH2 = C --- R1}} 

--- A_ {1} --- B_ {1} ---

 \ melm {\ delm {\ para} {R 3}} {N ^ {}} {\ uelm {\ para} {R 2}} 

--- Q

 \ hskip0.5cm 

X - wherein R 1 is H or CH 3; R2 and R 3 are each an alkyl group having 1 to 3 atoms of carbon, A 1 is O or NH; B1 is an alkylene group of 2 to 4 carbon atoms or a hydroxypropylene group, Q is benzyl X - it's a counterion anionic 8. A process according to any of the preceding claims, characterized in that the cationic organic polymer has an average molecular weight of at least 1,000,000. 9. A process according to any of the preceding claims, characterized in that the cationic organic polymer is prepared from a mixture of monomers comprising from 5 to 20 mol% of cationic monomer having an aromatic group and from 95 to 80 Mole% of other copolymerizable monomers. 10. A method according to any of the preceding claims, characterized in that the drainage and retention aid further comprises anionic inorganic particles. 11. A process according to claim 10, characterized in that the anionic inorganic particles are selected from particles based on silica or bentonite. 12. A process according to claim 10 or 11, characterized in that the anionic inorganic particles are selected from silica-based particles modified with aluminum 13. A process according to any of the preceding claims, characterized in that the drainage and retention aid further comprises a cationic organic polymer of low molecular weight. 14. A process according to any of the preceding claims, characterized in that the drain and retention aid further comprises an aluminum compound. 15. A method according to any of the preceding claims, characterized in that the suspension from which the water is removed in the metallic fabric has a content of di- and multivalent cations of at least 200 ppm. 16. A method according to any of the preceding claims, characterized in that the suspension comprises recycled fibers.