ES2384994T3 - A procedure for paper production - Google Patents

Abstract

Process for the production of paper from an aqueous suspension containing cellulosic fibers and optional fillers, comprising separately adding to the suspension a cationic organic polymer having one or more aromatic compounds, cationic polymer which is a cationic polysaccharide; and an anionic polymer having one or more aromatic groups, an anionic polymer that is selected from stepped growth polymers, polysaccharides and natural aromatic polymers and modifications thereof, forming and draining the suspension on a factory table, provided that , if the anionic polymer is a stepwise growth polymer, it is not an anionic melanin-sulfonic acid condensation polymer.

Description

A procedure for paper production.

The invention relates to papermaking and, more specifically, to a process for the production of paper in which cationic and anionic polymers having aromatic groups are added to the raw material for papermaking. The procedure provides improved drainage and retention.

Background

In the papermaking technique, an aqueous suspension containing cellulosic fibers and optional fillers and additives, called raw material of supply, from which the raw material is distributed on a factory table is supplied to a headboard drawer. The water from the raw material is drained through the factory table so that a wet net is formed on the table, which is then further dehydrated and dried in the drying section of the papermaking machine. The water obtained, usually called white water and containing fine particles such as fine fibers, fillers and additives, is usually recycled to the papermaking process. Conventional drainage and retention aids are conventionally introduced into the raw material of supply in order to facilitate drainage and retention and increase the adsorption of fine particles on the cellulose fibers so that they are retained with the fibers. A wide variety of drainage and retention aids are known in the art, for example, anionic, nonionic, cationic and amphoteric organic polymers, anionic and cationic inorganic materials, and many combinations thereof.

Publications of International Patent Application nos. WO 99/55964 and WO 99/55965 disclose the use of drainage and retention aids comprising organic polymers having aromatic groups. Organic polymers can be used alone or in combination with various anionic materials such as, for example, organic and inorganic anionic polymers, for example, sulfonated melanin-formaldehyde particles and silica-based particles.

GB 1,177,512 refers to an improved papermaking process. U.S. Patent

6,001,166 discloses an aqueous dispersion of alkyldicetene. WO 93/33979 describes an aqueous dispersion containing a reactive sizing agent against cellulose.

It would be advantageous to be able to provide a papermaking process with improved drainage and retention. It would also be advantageous to be able to provide drainage and retention aids comprising cationic organic polymers and anionic polymers with improved drainage and retention behavior.

The invention

In accordance with the present invention it has been found that improved drainage and / or improved retention can be obtained using drainage and retention aids comprising a cationic organic polymer having an aromatic group and an anionic polymer having an aromatic group. More specifically, the present invention relates to a process for the production of paper from an aqueous suspension containing cellulose fibers and optional fillers, comprising separately adding to the suspension a cationic polymer having an aromatic group, the polymer being cationic a cationic polysaccharide, and an anionic polymer having an aromatic group, the anionic polymer being selected from stepped growth polymers, polysaccharides and natural aromatic polymers and modifications thereof, forming and draining the suspension on a manufacturing table, with the condition that, if the anionic polymer is selected from stepwise growth polymers, it is not an anionic sulfonic melanin acid condensation polymer. The invention further relates to a process for the production of paper from an aqueous suspension containing cellulosic fibers and optional fillers, which comprises adding a cationic organic polymer having an aromatic group to the suspension, the cationic polymer being a cationic polysaccharide. , and an anionic polymer having an aromatic group, forming and draining the suspension on a factory table, with the proviso that the anionic polymer is not an anionic polystyrene sulfonate or an anionic melamine-sulfonic acid condensation polymer. The invention also relates to a process as defined in the claims.

The term "· drainage and retention aids" as used herein refers to two or more components that,

when added to an aqueous cellulosic suspension, they give better drainage and / or retention than is obtained without adding the two or more mentioned components.

The present invention results in improved drainage and / or improved retention in the production of paper from all types of raw materials, in particular raw materials that have high salts (high conductivity) and colloidal substances, and / or in papermaking processes with a high degree of clear water return, that is, high recycling of clear water and limited supply of fresh water. Therefore, this

The invention makes it possible to increase the speed of the paper machine and use a lower dosage of additives to obtain the corresponding drainage and / or retention effect, thus leading to an improved papermaking process and economic benefits. The present invention also provides paper with an improved dry strength.

 The cationic organic polymer having an aromatic group according to the present invention can be derived from natural or synthetic sources, and can be linear, branched or crosslinked. Preferably, the cationic polymer is water soluble or water dispersible. Examples of suitable cationic polymers include cationic polysaccharides, for example, starches, guar gums, celluloses, chitins, chitosans, glucans, xanthan gums, pectin, corn, mannan, dextrin, preferably starches and guar gums, including Suitable starches are those of potato, corn, tapioca, rice, waxy corn, barley, etc., synthetic organic polymers such as cationic chain growth polymers, for example, cationic vinyl addition polymers such as acrylate, acrylamide, vinylamine based polymers. and vinylamide, and stepwise cationic polymers, for example, cationic polyurethanes. Cationic starches and cationic acrylamide-based polymers having an aromatic group are particularly preferred cationic polymers.

The cationic organic polymer according to the invention has one or more aromatic groups and the aromatic groups may be the same or different groups. The aromatic group of the cationic organic polymer may be present in the main chain (skeleton) or in a substituent group that is attached to the polymer backbone, preferably in a substituent group. Examples of aromatic groups include the aryl, arylalkyl and alkylaryl groups, for example, phenyl, phenylene, naphthyl, phenylene, xylylene, benzyl and phenylethyl; aromatic groups (aryl) containing nitrogen, for example, pyridinium and quinolinium, as well as derivatives of these groups, preferably benzyl. Examples of cationically charged groups that may be present in the cationic polymer as well as in monomers used to prepare the cationic polymer include quaternary ammonium groups, tertiary amino groups and acid addition salts thereof.

According to a preferred embodiment of this invention, the cationic organic polymer having an aromatic group is a polysaccharide represented by the general structural formula (I):

in which P is a remainder of a polysaccharide; A is a group that links N to the rest of the polysaccharide, suitably a chain of atoms comprising C atoms and, optionally, O and / or N atoms, usually an alkylene group with 2 to 18 and, suitably, 2 to 8 carbon atoms, optionally interrupted or substituted by one or more heteroatoms, for example O or N, for example an alkyleneoxy group or a hydroxypropylene group (-CH2-CH (OH) -CH2-); R1 and R2 are each, H, or preferably, a hydrocarbon group, suitably alkyl having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms; Q is a substituent that contains an aromatic group, suitably a substituted phenyl or phenyl group that may be attached to nitrogen through an alkylene group that usually has 1 to 3 carbon atoms, suitably 1 to 2 carbon atoms, and preferably Q is a benzyl group (-CH2-C6H5); n is an integer, usually from about 2 to about 300,000, suitably from 5 to 200,000 and, preferably, from 6 to

125,000 or, alternatively, R1, R2 and and Q together with Q form an aromatic group containing from 5 to 12 atoms of

carbon; and X ’is an anionic counterion, usually a halide such as chloride. Among the suitable polysaccharides

represented by the general formula (I) listed above. The cationic polysaccharides according to the invention may also contain anionic groups, preferably in a minor amount. Such anionic groups can be introduced into the polysaccharide by chemical treatment or they can be present in the native polysaccharide.

According to another preferred embodiment of the invention, the cationic organic polymer having an aromatic group is a chain growth polymer. The term "chain growth polymer", as used herein, refers to a polymer obtained by polymerization with chain growth, and is also referred to as chain reaction polymer and chain reaction polymerization. Examples of chain growth polymers include vinyl addition polymers prepared by polymerization of a monomer or several monomers having a vinyl group or an ethylenically unsaturated bond, for example, a polymer obtained by polymerization of a cationic monomer or mixture of monomers comprising a cationic monomer represented by structural formula (II)

wherein R is H or CH3; R1 and R2 are each, H or, preferably, a hydrocarbon group which suitably has 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms; A2 is O or NH; B2 is an alkyl or alkylene group having 2 to 8 carbon atoms, suitably 2 to 4 carbon atoms, or a hydroxypropylene group; Q is a substituent containing an aromatic group, suitably a substituted phenyl or phenyl group, which may be attached to the nitrogen by an alkylene group that usually has 1 to 3 carbon atoms, suitably 1 to 2 carbon atoms, and, preferably , Q is a benzyl group (-CH2-C6H5); and X ’is an anionic counterion, usually a halide such as chloride.

Examples of suitable monomers represented by the general formula (II) include quaternary monomers obtained by treating dialkylaminoalkyl (meth) acrylates, for example, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and (meth) acrylate dimethylaminohydroxypropyl, and dialkylaminoalkyl (meth) acrylamides, for example, dimethylaminoethyl (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, with benzoyl chloride. Preferred cationic monomers of the general formula (I) include the quaternary salt of dimethylaminoethyl acrylate benzyl chloride and the quaternary salt of dimethylaminoethyl methacrylate benzyl chloride. The monomer of the formula

(II) can be copolymerized with one or more nonionic, cationic and / or anionic monomers. Suitable copolymerizable non-ionic monomers include met (acrylamide); acrylamide-based monomers such as Nalkyl (meth) acrylamides, N, N-dialkyl (meth) acrylamides and dialkylaminoalkyl (mert) acrylamides, acrylate-based monomers such as dialkylaminoalkyl (meth) acrylates, and vinylamides. Suitable copolymerizable cationic monomers include addition salts and quaternary salts of dimethylaminoethyl (meth) acrylate and dialkyldimethylammonium chloride. The cationic organic polymer may also contain anionic groups preferably in a minor amount. Suitable copolymerizable anionic monomers include acrylic acid, methacrylic acid and various sulfonated vinyl monomers such as styrenesulfonate. Preferred copolymerizable monomers include acrylamide and methacrylamide, that is, (meth) acrylamide, and the cationic or amphoteric organic polymer preferably is an acrylamide-based polymer.

The cationic vinyl addition polymers according to this invention can be prepared from a mixture of monomers comprising from 1 to 99 mol%, suitably from 2 to 50 mol% and, preferably, from 5 to 20 mol% of a cationic monomer having an aromatic group and 99 to 1 mol%, suitably 98 to 50 mol%, and preferably 95 to 80 mol% of other copolymerizable monomers that preferably comprise acrylamide or methacrylamide ((met ) acrylamide), a mixture of monomers that suitably comprises 98 to 50 mol% and, preferably, 95 to 80 mol% of (meth) acrylamide, 100 being the sum of the percentages.

Examples of suitable cationic polymers of stepped growth according to the invention include cationic polyurethanes which can be prepared from a mixture of monomers comprising aromatic isocyanates and / or aromatic alcohols. Examples of suitable aromatic isocyanates include diisocyanates, for example toluene-2,4- and 2,6-diisocyanates and diphenylmethane-4,4'-diisocyanate. Examples of suitable aromatic alcohols include dihydroxy alcohols, that is, diols, for example bisphenol A, phenyldiethanolamine, glycerol monoterephthalate and trimethylolpropane monoterephthalate. Monohydroxy aromatic alcohols such as phenol and its derivatives can also be used. The monomer mixture may also contain isocyanates and / or non-aromatic alcohols, usually diisocyanates and diols, for example any of those known as useful in the preparation of polyurethanes. Examples of suitable monomers containing cationic groups include cationic diols such as acid addition salts and quaternization products of N-alkanedioldialkylamines and N-alkyldialkanolamines such as 1,2-propanediol-3-dimethylamine, N-methyldiethanolamine, N-ethyldiethanolamine, N -propyldiethanolamine, Nn-butyldiethanolamine and Nt-butyldiethanolamine, Nestearyldiethanolamine and N-methyldipropanlamine. Quaternization products can be derived from alkylating agents such as methyl chloride, methyl sulfate, benzyl chloride and epichlorohydrin.

The average weight molecular weight of the cationic polymer can vary between very wide limits depending, inter alia, on the type of polymer used and is usually at least greater than 5,000 and, often, greater than 10,000. More frequently, it is greater than 150,000, usually greater than 500,000, suitably greater than approximately 700,000, preferably greater than approximately 1,000,000 and, most preferably, greater than approximately 2,000,000. The upper limit is not critical; It can be about 200,000,

usually sw 150,000,000 and suitably 100,000,000.

The cationic organic polymer can have a cationic substitution degree (DSc) that varies over a wide range depending, inter alia, on the type of polymer used; DSc can be 0.005 to 1.0, usually 0.01 to 0.5, suitably 0.02 to 0.3, preferably 0.025 to 0.2, and the degree of aromatic substitution (DSa) can be 0.001 to 0.5, usually 0.01 to 0.5, suitably 0.02 to 0.3, and preferably 0.025 to 0.2. In the event that the cationic organic polymer contains anionic groups, the degree of anionic substitution (DSA) may be from 0 to 0.2, suitably from 0 to 0.1 and, preferably, from 0 to 0.05, having the cationic polymer a global cationic charge. Usually, the charge density of the cationic polymer is in the range of 0.1 to 6.0 mequiv / g dry polymer, suitably 0.2 to 5.0 and, preferably, 0.5 to 4.0.

Examples of cationic organic polymers having an aromatic group that can be used in accordance with the invention include those described in International Patent Publications nos. WO 99/55964, WO 99/55965 and 99/67310.

Anionic polymers having an aromatic group according to the invention can be selected from stepwise growth polymers, chain growth polymers, polysaccharides, natural aromatic polymers and modifications thereof. The term "stepwise growth polymer, as used herein, refers to a polymer obtained by stepwise growth polymerization, which is also referred to as a stepwise reaction polymer and stepwise reaction polymerization, respectively. Preferably, the anionic polymer is selected from stepwise growth polymers, polysaccharides and natural aromatic polymers, and modifications thereof, most preferably stepwise growth polymers. The anionic polymers according to the invention can be linear, branched or crosslinked. Preferably, the anionic polymer is water soluble or water dispersible. The anionic polymer is preferably organic.

The anionic polymer according to the invention has one or more aromatic groups and the aromatic groups may be the same or different. The aromatic group of the anionic polymer may be present in the polymer backbone or in a substituent group attached to the backbone of the polymer (main chain). Examples of suitable aromatic groups include aryl, arylalkyl and alkylaryl groups, and derivatives thereof, for example, phenyl, tolyl, naphthyl, phenylene, xylylene, benzyl, phenylethyl and derivatives of these groups. Examples of anionically charged groups that may be present in the anionic polymer as well as in the monomers used to prepare the anionic polymer include groups that have an anionic charge and acidic groups that have an anionic charge when dissolved or dispersed in water, groups which are collectively referred to herein as anionic groups, such as phosphate, phosphonate, sulfate, sulphonic acid, sulfonate, carboxylic acid, carboxylate, alkoxide and phenolic groups, that is, hydroxyl substituted phenyls and naphthyl. Groups that have an anionic charge are usually alkali metal, alkaline earth metal or ammonium salts.

Suitable anionic step-growth polymers according to the present invention include condensation polymers, that is, polymers obtained by step-growth condensation polymerization, for example, condensates of an aldehyde such as formaldehyde with one or more aromatic compounds containing one or more anionic groups, and other optional comonomers useful in condensation polymerization, such as urea and melanin. Examples of suitable aromatic compounds containing anionic groups comprise benzene and naphthalene-based compounds containing anionic groups such as phenolic and naphtholic compounds, for example, phenol, naphthol, resorcinol and derivatives thereof, aromatic acids and salts thereof, for example. , phenyl, phenolic, naphthyl and naphtholic acids and their salts, usually sulfonic acids and sulphonates, for example benzenesulfonic acid and sulfonates, xylylenesulfonic acid and sulphonates, naphthalenesulfonic acid and sulfonate, phenolsulfonic acid and sulfonate. Examples of suitable anionic step-growth polymers according to the invention include anionic condensation polymers based on benzene and based on naphthalene, preferably condensation polymers based on naphthalenesulfonic acid and based on naphthalene sulfonate.

Examples of other suitable stepwise growth anionic polymers according to the present invention include addition polymers, that is, polymers obtained by stepwise growth addition polymerization, for example, anionic polyurethanes that can be prepared from a mixture of monomers comprising aromatic isocyanates and / or aromatic alcohols. Examples of suitable aromatic isocyanates include diisocyanates, for example, toluene-2,4- and 2,6-diisocyanates and diphenylmethane-4,4'-diisocyanate. Examples of suitable aromatic alcohols include dihydroxy alcohols, that is, diols, for example bisphenol A, phenyldiethanolamine, glycerol monoterephthalate and trimethylolpropane monoterephthalate. Monohydroxy aromatic alcohols such as phenol and derivatives can also be used. The monomer mixture may also contain isocyanates and / or non-aromatic alcohols, usually diisocyanates and diols, for example, any of those known as useful in the preparation of polyurethanes. Examples of monomers containing anionic groups include the monoester reaction products of triols, for example, trimethylolethane, trimethylolpropane and glycerol, with dicarboxylic acids or their anhydrides, for example acid and succinic anhydride, acid or terephthalic anhydride, such as monosuccinate glycerol, glycerol monoterephthalate, trimethylolpropane monosuccinate, trimethylolpropane monoterephthalate, N, N-bis- (hydroxyethyl) -glycine, di- (hydroxymethyl) propionic acid, N, N-bis- (hydroxyethyl) -2-aminoethanesulfonic acid , optionally and usually in combination with reaction with a base such as alkali metal or alkaline earth metal hydroxide, for example, sodium hydroxide, ammonia or an amine, for example triethylamine, thus forming a counterion of an alkali metal, alkaline earth metal or ammonia metal.

Examples of suitable anionic chain growth polymers according to the invention include addition vinyl polymers obtained from a mixture of vinyl or ethylenically unsaturated monomers comprising at least one monomer having an aromatic group and at least one monomer having an anionic group, usually copolymerized with non-ionic monomers such as acrylate-based and acrylamide-based monomers. Suitable anionic examples include (meth) acrylic acid and paravinylphenol (hydroxystyrene).

Examples of suitable anionic polysaccharides include starches, guar gums, celluloses, chitins, chitosans, glycans, galactans, xanthan gums, pectins, mannan, dextrins, preferably starches, guar gums and cellulose derivatives, including suitable starches those of potato, corn, wheat, tapioca, rice, waxy corn and barley, preferably potato. The anionic groups of the polysaccharide can be native or introduced by chemical treatment. The aromatic groups of the polysaccharide can be introduced by chemical methods known in the art.

Among the natural aromatic anionic polymers and their modifications, for example, modified natural aromatic anionic polymers, according to the invention, include natural polyphenolic substances that are present in the wood and organic bark extracts of some wood species and their chemical modifications , usually sulfonated modifications thereof. The modified polymers can be obtained by chemical processes such as, for example, pulp formation with sulphite and by the kraft process. Examples of suitable anionic polymers of this type include lignin-based polymers, preferably sulfonated lignins, for example, lignosulfonates, kraft lignin, sulfonated kraft lignin and tannin extracts.

The average weight molecular weight of the anionic polymer can vary over a wide range depending, inter alia, on the type of polymer used and is usually at least about 500, usually greater than about 2,000, usually and, preferably, greater than about 5,000. The upper limit is not critical; it can be about 200,000,000, usually 150,000,000, suitably 100,000,000 and preferably 10,000,000.

The anionic polymer can have an anionic substitution degree (DSA) that varies over a wide range depending, inter alia, on the type of polymer used; DSA is usually 0.01 to 2.0, suitably 0.02 to 1.8, and preferably 0.025 to 1.5; and the degree of aromatic substitution (DSa) may be from 0.001 to 1.0, usually from 0.01 to 0.8, suitably from 0.02 to 0.7 and, preferably, from 0.025 to 0.5. In the event that the anionic polymer contains cationic groups, the degree of cationic substitution (DSc) can be, for example, from 0 to 0.2, suitably from 0 to 0.1 and, preferably, from 0 to 0.05 , the polymer having an overall anionic charge. Usually, the anionic charge density of the anionic polymer is in the range of 0.1 to 6.0 mequiv / g dry polymer, suitably 0.5 to 5.0 and, preferably, 1.0 to 4.0 .

Examples of suitable anionic aromatic polymers that can be used in accordance with the invention include those described in U.S. Pat. us. 4,070,238 and 5,755,930; and European Patent Application publications nos. WO 95/21295, WO 95/21296, WO 99/87310 and WO 00/49227.

Particularly preferred combinations of anionic and cationic polymers having aromatic groups, as defined above, in accordance with the present invention include

(i)

cationic polysaccharides, preferably cationic starch, and stepwise growth anionic polymers, suitably anionic polymers based on benzene and condensation polymers based on naphthalene and anionic polyurethanes, preferably anionic condensation polymers based on naphthalene;

(ii)

 cationic polysaccharides, preferably cationic starch, and natural aromatic polymers and their modifications, suitably anionic polymers based on lignin, preferably sulfonated lignins;

(iii) cationic chain growth polymers, suitably cationic vinyl addition polymers, preferably acrylamide-based cationic polymers, and anionic chain growth polymers, suitably benzene-based and anionic condensation anionic polymers based on naphthalene and anionic polyurethanes, preferably anionic condensation polymers based on naphthalene, and

(iv) cationic chain growth polymers, suitably cationic vinyl addition polymers, preferably acrylamide-based cationic polymers, and natural aromatic anionic polymers and modifications thereof, suitably lignin-based anionic polymers, preferably sulfonated lignin.

The cationic and anionic polymers according to the invention are preferably added separately to the aqueous solution containing cellulosic fibers, or delivery raw material, and not as a mixture containing said polymers. Preferably, the cationic and anionic polymers are added to the supply raw material at different points. The polymers can be added in any order. Usually the cationic polymer is first added to the raw material of supply and then the anionic polymer is added, although the reverse order of addition can also be followed. The polymers can be added to the dehydrated raw material in amounts that can vary between wide limits depending, inter alia, on the type of the raw material of supply, the content of salts, the type of salts, the content of load, the type of load, the point at which they are added, etc. Generally, the polymers are added in an amount that gives better drainage and / or retention than is obtained when they are not added and usually the cationic polymer is added to the supply raw material before adding the anionic polymer. Usually, the cationic polymer is added in an amount of at least 0.001%, with a frequency of at least 0.005% by weight, in relation to the matter of dry supply, while the upper limit is usually 3%, suitably 2, 0% by weight. The anionic polymer is usually added in an amount of at least 0.001%, with a frequency of at least 0.005% dry, in relation to the dry supply matter, while the upper limit is usually 3% and suitably 1.5 % in weigh.

Polymers having aromatic groups according to the invention can be used together with additional additive (s) that are beneficial for the overall drainage and / or retention behavior, constituting drainage and retention aids comprising three or more components. . Examples of suitable additives of this type include anionic microparticle materials, for example, silica-based particles, low molecular weight cationic organic polymers, aluminum compounds, anionic vinyl addition polymers, and combinations thereof, including compounds and their use described in publications of International Patent Application nos. WO 99/55964 and WO 99/55965.

Among the cationic organic polymers of low molecular weight (hereinafter LMW) that can be used according to the invention are those which are commonly referred to as anionic garbage collectors (ATC). The cationic organic polymer of (LMW) can be obtained from natural or synthetic sources and is preferably a synthetic polymer of LMW. Suitable organic polymers of this type include highly charged LMW cationic organic polymers, such as polyamines, polyamidoamines, polyethylamines, homopolymers and copolymers based on dialkylmethylammonium chloride, (meth) acrylamides and (meth) acrylates. As for the molecular weight of the cationic organic polymer of this invention having an aromatic group, the molecular weight of the LMW cationic organic polymer is preferably low; suitably it is at least 2,000 and preferably at least 10,000. The upper limit of the molecular weight is usually about 700,000, suitably about 500,000 and usually about 200,000.

Among the aluminum compounds that can be used according to the invention are alum, aluminates, aluminum chloride, aluminum nitrate and polyaluminium compounds such as polyaluminium chloride, polyaluminium sulfates, polyaluminium compounds containing the two chloride ions and sulfate, polyaluminium silicosulfates, and mixtures thereof. The polyaluminium compounds may also contain other anions other than the chloride ion, for example, sulfuric acid anions, phosphoric acid, organic acids such as citric acid and oxalic acid.

The process of the invention is applicable to all papermaking processes and cellulosic suspensions and is particularly useful in the manufacture of paper from a raw material that has a high conductivity. In such cases, the conductivity of the supply raw material that has been dehydrated on a dry factory table is usually at least 2.0 mS / cm, suitably at least 3.5 mS / cm. The conductivity can be measured with standard equipment such as, for example, a WTW LF 539 instrument, supplied by Christian Bermer. The values referred to above are suitably determined by measuring the conductivity of the cellulosic suspension that is supplied to the header drawer of the paper machine or is present therein or, alternatively, by measuring the conductivity of the white water obtained by dehydration. of the suspension. High conductivity levels mean high contents of salts (electrolytes) that can come from the materials used to form the raw material for supply, various additives added to the raw material, fresh water supplied to the process, etc. In addition, the salt content is usually higher in processes in which white water is recirculated extensively, which can lead to a considerable accumulation of salts in the circulating water.

The present invention further encompasses papermaking processes in which it recycles or recirculates white water extensively, that is, with a high degree of white water maintenance, for example, in which per ton of dry paper produced 0 to 30 tons of fresh water, usually less than 20, suitably less than 15, preferably less than 10 and notably less than 5 tons of fresh water per ton of paper. The recycling of white water obtained in the process of the invention suitably comprises mixing the white water with cellulosic fibers and / or optional fillers with a suspension forming a suspension to be dehydrated; preferably it comprises mixing the white water with a suspension containing cellulosic fibers and optional charges before the suspension enters the factory table for dehydration. White water may be mixed with the suspension before, between, simultaneously or after introducing the drainage and retention aids of this invention. Fresh water can be introduced into the procedure at any stage; for example, it can be mixed with cellulosic fibers in order to form a suspension, and it can be mixed with a thick suspension containing cellulosic fibers to dilute it forming a light suspension to dehydrate before, simultaneously or after mixing the suspension with white water.

Obviously, other additives that are conventional in papermaking can be used in combination with the polymers according to the invention, such as, for example, dry strength agents, wet strength agents, optical brightening agents, agents sizing agents such as rosin-based sizing agents and cellulose reactive sizing agents, for example, alkyl and alkenyl cetene dimers, alkyl alkenyl cetene multimers, and succinic anhydrides, etc. The suspension, or raw material for supply, may also contain conventional mineral charges such as, for example, kaolin, clay from China, titanium dioxide, gypsum, talc and natural and synthetic calcium carbonates such as crete, ground marble and carbonate precipitated calcium.

The process of this invention is used for paper production. The term "paper," as used herein, obviously includes not only paper and its production, but also other cellulosic products that contain sheet or web fibers, such as, for example, cardboard and corrugated paper, and their production. The process can be used in the production of paper of different types of cellulose-containing fiber suspensions and the suspensions should suitably contain at least 25% by weight and, preferably, at least 50% by weight of such fibers, on the basis of dry substance The suspension may be based on chemical pulp fibers, such as sulfate, sulphite and organic solvent pulps, mechanical pulps such as thermomechanical pulp, chemothermomechanical pulp, refining pulp and ground wood pulp, both hardwood and softwood pulp. , and may also be based on recycled fibers, optionally of destined pulps, and mixtures thereof.

The invention is further illustrated with the following Examples, which are not limited in purpose. Parts and percentages are by weight, unless otherwise indicated.

Example 1

The cationic polymers used in the assays were purchased on the market or prepared by generally known procedures. The cationic polysaccharides used in the assays were prepared by reacting native potato starch with a quaternization agent according to the general procedure described in EP-A-0 189 935 and WO 99/55964. The cationic polymers used in the tests, here collectively referred to herein also as C1-3 cationic polymers according to the invention and C1-ref-C3-ref for comparative purposes were the following:

C1 Cationic starch obtained by quaternization of native potato starch with 0.5% N-3-chloro-2-hydroxypropyl dimethylbenzylammonium chloride.

C2 Cationic starch obtained by quaternization of native potato starch with 0.7% N-3-chloro-2-hydroxypropyl dimethylbenzylammonium chloride.

C3 Vinyl addition polymer prepared by polymerization of acrylamide (90 mol%) and acryloxidimethylbenzylammonium chloride (10 mol%) of molecular weight of approximately 6,000,000.

C1-ref. Cationic starch obtained by quaternization of native potato starch with 2,3% epoxypropyltrimethylammonium chloride at 0.8% N.

C2-ref, cationic starch obtained by quaternization of native potato starch with 2,3% epoxypropyltrimethylammonium chloride at 0.5% N.

C3-ref. Vinyl addition polymer prepared by polymerization of acrylamide (90 mol%) and acryloximethylbenzylammonium chloride (10 mol%) of molecular weight of approximately 6,000,000.

The anionic polymers used in the assays were purchased on the market or prepared by generally known procedures. The anionic polymers used in the tests, referred to below also as anionic polymer A1 to A8 according to the invention and A1-ref to A2-ref whose purpose is for comparison were the following:

A1 Anionic polycondensate of the formaldehyde type with naphthalenesulfonate, of a molecular weight of approximately 20,000.

A2 Anionic polycondensate of the formaldehyde type with naphthalenesulfonate, of a molecular weight of approximately 110,000.

A3 Anionic polycondensate of the formaldehyde type with naphthalenesulfonate, of a molecular weight of approximately 40,000.

A4 Anionic polycondensate of the formaldehyde type with naphthalenesulfonate, of a molecular weight of approximately 210,000.

A5 Anionic polyurethane obtained by reacting glycerol monostearate with toluene diisocyanate to form a prepolymer containing terminal isocyanate groups that then react with trimethylolpropionic acid.

A6 Anionic polyurethane obtained by reacting phenyldiethanolamine with toluene diisocyanate to form a prepolymer containing terminal isocyanate groups that then react with trimethylolpropionic acid and Nmethyldiethanolamine.

A7

Anionic sulfonated kraft lignin.

A8

Anionic lignosulfonate.

A1-ref

Anionic polycondensate of melamine-formaldehyde-sulphonate.

A2-ref

Inorganic silicon acid condensation anionic polymer in the form of colloidal silica particles

with a particle size of 5 nm.

A low molecular weight cationic organic polymer, also called ATC, was used commercially by generally known methods, which was used in some of the assays. The ATC was the following:

AT Cationic copolymer of dimethylamine, epichlorohydrin and ethylenediamine, of a molecular weight of approximately 50,000

All polymers were used in the form of dilute aqueous solutions of polymer.

Example 2

The drainage behavior was evaluated with a Dynamic Drainage Analyzer (DDA) available in Akribi, Sweden, which measures the drainage time of a given volume of raw material for supply through a factory table opposite the side on which it is located. Present the raw material supply.

A standard raw material of a supply with 56% by weight of peroxide bleached TMP / SWG pulp (80/20), 14% by weight of bleached birch / pine sulfate pulp (60/40) refined at 200 ° CSF was prepared and 30% by weight of clay from China. To the prepared raw material were added 25 g / l of a colloidal fraction, bleaching water from a bin. The volume of the raw material was 800 ml and the pH was approximately 7. Calcium chloride was added to adjust the conductivity to 0.5 mS / cm. The raw material thus prepared was called the standard raw material. Additional amounts of calcium chloride were added thereto in order to prepare a sample of medium conductivity (2.0 mS / cm) and a sample of high conductivity (5.0 mS / cm).

The prepared feedstock was stirred in a jar with baffles at 1500 rpm throughout the test and the addition of chemicals was done as follows: (i) adding cationic polymer to the raw material after stirring for 30 s, (ii) addition of anionic polymer to the raw material and then stirring for 15 s,

(iii) drainage of the raw material while the drainage time was automatically recorded. If used, the ATC was added and then stirred for 30 s before (i) adding cationic polymer and (ii) adding anionic polymer according to the above procedure.

Table 1 shows the effect of dehydration (drainage) for various dosages of cationic polymer C1, calculated as dry polymer on dry raw material system, and various dosages of anionic polymers A1-ref, A1 and A2, calculated as dry polymer on dry raw material system. The standard raw material was used in Essays nos. 1-5 and the high conductivity raw material was used in Tests nos. 6-9.

Table 1

Test No.

C1 TO         Dehydration time, s

Dose, kg / t

    Dose, kg / t  A1-ref A1 A2

1 2 3 4 5 6 7 8 9

30 30 30 30 30 20 20 20 20 0 0.5 1.0 2.0 3.0 0 2.0 3.0 4.0 19.0 17.5 14.6 12.8 9.8 26.4 21.5 17.6 15.7 19.0 17.0 12.6 9.0 8.7 26.4 15.7 14.6 14.5 19.0 15.5 12.1 8.4 7.2 26.4 15.6 13.7 13.4

Example 3

First pass retention was evaluated with a nephelometer by measuring the turbidity of the filtrate of a Dynamic Drainage Analyzer (DDA), the white water, obtained by draining the raw material obtained in Example 2. The results are given in Table 2 .

10 Table 2

Test No.

C1 TO Turbidity, NTU

Dose, kg / t

Dose, kg / t

A1-ref A1 A2

1 2 3 4

30 30 30 30 0.5 1.0 2.0 3.0 56 55 52 50 49 50 47 43 55 50 48 45

Example 4

Drainage behavior was evaluated using the cationic and anionic polymers according to Example 1 and the standard raw material and the procedure according to Example 2. The results are shown in Table

15 3.

Table 3

Test no.

C1 TO Dehydration time, s

Dose, kg / t

Dose, kg / t

A1 A3 A4

1 2 3 4 5

0 20 20 20 20 0 0 1.0 2.0 4.0 18.0 12.5 10.9 10.3 10.0 18.0 12.5 10.0 9.0 8.7 18.0 12.5 10.2 8.9 8.0

Example 5

Drainage behavior was evaluated using the cationic and anionic polymers according to Example 1 and the medium conductivity raw material and the procedure according to Example 2. The results are shown in Table 4.

Table 4

Test no.

C A1 Dehydration time, s

Dose, kg / t

Dose, kg / t

C1-ref C1 C2

1 2 3 4

10 10 10 10 0 0.78 1.5 3.0 13.8 12.6 12.8 14.1 14.6 10.6 9.5 10.1 11.5 7.4 6.6 7.2

Example 6

The drainage behavior was evaluated using the cationic and anionic polymers according to Example 1 and the high conductivity raw material and the procedure according to Example 2. The results are shown in Table 5.

Table 5 Example 7

Test no.

C A1 Dehydration time, s

Dose, kg / t

Dose, kg / t

A2-ref TO 5 A6

1 2 3 4 5

20 20 20 20 20 0 1.0 2.0 4.0 6.0 31.8 31.0 28.0 23.8 23.0 31.8 27.5 22.0 16.5 14.0 31.8 28.8 24.4 19.5 18.3

Drainage behavior was evaluated using the cationic and anionic polymers according to Example 1 and the high conductivity raw material and the procedure according to Example 2. The results are shown in Table 6.

Table 6

Test no.

C3 TO Dehydration time, s

Dose, kg / t

Dose, kg / t

TO 5 A6

1 2 3 4 5

2 2 2 2 2 0 0.25 0.5 0.75 1.0 15.8 13.8 13.2 13.4 13.5 15.8 13.3 12.9 13.1 13.3

Example 8

The drainage behavior was evaluated using the cationic and anionic polymers according to Example 1 and the standard conductivity raw material and the procedures according to Examples 2 and 3. The results are shown in Table 7.

Table 7

Test no.

C Dose, kg / t A7 Dose, kg / t Dehydration time / Turbidity, s / NTU

C2-ref

 C1

1 2 3

25 25 25 0 2 4 22.0 / 49 22.1 / 50 21.2 / 46 23.4 / 43 16.3 / 40 14.3 / 40

Example 9

The drainage behavior was evaluated using the cationic and anionic polymers and the ATC according to Example 1 and the medium conductivity raw material and the procedure according to Example 2. The results are shown in Table 8.

Table 8 Example 10

Test no.

ATC C A7 Dehydration time, s

Dose, kg / t

Dose, kg / t

Dose, kg / t

C3-ref C3

1 2 3

3 3 3 3 3 3 1 1.5 2 20.8 17.9 14.7 11.0 9.3 7.9

Drainage and retention behavior was evaluated using cationic and anionic polymers and ATC according to Example 1 and the medium conductivity raw material and procedures according to Examples 2 and 3. The results are shown in Table 9. .

Table 9

Test no.

ATC Dose, kg / t C Dose, kg / t A8 Dose, kg / t Dehydration time / Turbidity, s / NTU

C3-ref

C3

1 2 3

3 3 3 3 3 3 2. 3. 4 21.4 / 49 17.4 / 46 15.6 / 48 11.1 / 40 9.3 / 40 8.9 / 45

Example 11

Drainage behavior was evaluated using the cationic and anionic polymers according to Example 1 and the standard conductivity raw material and the procedures according to Example 2. The results are shown in Table 10.

Table 10

Test no.

C Dose, kg / t A8 Dose, kg / t Dehydration time / Turbidity, s / NTU

C2-ref

C1

1 2 3 4 5

25 25 25 25 25 1 2 4 6 8 23.0 / 47 22.6 / 50 22.8 / 49 22.6 / 49 22.1 / 50 20.8 / 44 19.0 / 43 18.8 / 45 16.3 / 40 15.5 / 42

Claims (26)

one.

Process for the production of paper from an aqueous suspension containing cellulosic fibers and optional fillers, comprising separately adding to the suspension a cationic organic polymer having one or more aromatic compounds, cationic polymer which is a cationic polysaccharide; and an anionic polymer having one or more aromatic groups, an anionic polymer that is selected from stepped growth polymers, polysaccharides and natural aromatic polymers and modifications thereof, forming and draining the suspension on a factory table, provided that , if the anionic polymer is a stepwise growth polymer, it is not an anionic melanin-sulfonic acid condensation polymer.

2.

Process for the production of paper from an aqueous suspension containing cellulosic fibers and optional fillers, comprising separately adding to the suspension a cationic organic polymer having one or more aromatic compounds, cationic polymer that is a cationic polysaccharide, and a polymer anionic having one or more aromatic groups, forming and draining the suspension on a factory table, with the proviso that the anionic polymer is not an anionic polystyrene sulfonate polymer or a melanin-sulfonic acid condensation polymer.

3.

Process according to any one of the preceding claims, characterized in that the anionic polymer is selected from condensates of an aldehyde, anionic polyurethanes and natural aromatic polymers and modifications thereof.

Four.

Process according to any one of the preceding claims, characterized in that the anionic polymer is selected from condensates of an aldehyde and naphthalene-based compounds, anionic polyurethanes that are prepared from a mixture comprising aromatic isocyanates and / or aromatic alcohols, and lignin based polymers.

5.

Process according to any one of claims 1 to 3, characterized in that the anionic polymer is selected from stepwise growth polymers that are condensation polymers based on benzene or based on naphthalene.

6.

Process according to claim 1 or 2, characterized in that the anionic polymer is prepared from one or more aromatic compounds selected from phenyl, phenol, naphthalene, naphthol and derivatives and mixtures thereof.

7.

Process according to claim 1 or 2, characterized in that the anionic polymer is selected from tannin extracts, sulfonated lignins, benzenesulfonic acid, benzenesulfonate, xylenesulfonic acid, xylenesulfonate, naphthalenesulfonic acid, naphthalenesulfonate, phenolsulfonic acid, phenolsulfonate and mixtures thereof.

8.

Process for the production of paper from an aqueous suspension containing cellulosic fibers and optional fillers, comprising separately adding to the suspension a cationic organic polymer having one or more aromatic compounds, and an anionic polymer having one or more aromatic groups. , an anionic polymer that is selected from aromatic polyurethanes, anionic polysaccharides and natural anionic aromatic polymers and modifications thereof, forming and draining the suspension on a factory table, with the proviso that the anionic polymer is not an anionic polystyrene sulfonate polymer or a anionic polymer of melanin-sulfonic acid condensation.

9.

 Process according to claim 1 or 2, characterized in that the cationic polymer is cationic starch.

10.

Process according to claim 8, characterized in that the cationic polymer is a vinyl addition polymer.

eleven.

Process according to claim 10, characterized in that the cationic polymer is an acrylamide based polymer.

12.

Process according to any one of the preceding claims, characterized in that the cationic polymer has a weight average molecular thickness greater than about 1,000,000.

13.

Process according to any one of the preceding claims, characterized in that the cationic polymer has a benzyl group.

14.

Process according to any one of claims 1 and 2, and from 8 to 13, characterized in that the anionic polymer is selected from anionic polyurethanes and natural and anionic aromatic polymers and

Modifications thereof.

fifteen.

Process according to any one of claims 1 and 2, and from 8 to 14, characterized in that the anionic polymer is selected from anionic polyurethanes that are prepared from a mixture comprising aromatic isocyanates and / or aromatic alcohols, and based polymers in lignin.

16.

Process according to claim 8, characterized in that the anionic polymer is anionic polyurethane.

17.

Process according to claim 16, characterized in that the anionic polyurethane is prepared from a mixture of monomers comprising aromatic isocyanates and / or aromatic alcohols.

18.

Process according to any one of claims 1, 2 and 8, characterized in that the anionic polymer is a lignin-based polymer.

19.

Process according to any one of claims 1 to 5, characterized in that the anionic polymer is a condensation polymer of formaldehyde-naphthalenesulfonate.

twenty.

Process according to any one of the preceding claims, characterized in that the anionic polymer has a weight average molecular weight in the range of 500 to 1,000,000.

twenty-one.

Process according to any one of the preceding claims, characterized in that the cationic polymer is added in an amount of 0.005 to 2% by weight in relation to the dry suspension.

22

Process according to any one of the preceding claims, characterized in that the anionic polymer is added in an amount of 0.005 to 1.5% by weight in relation to the dry suspension.

2. 3.

 Process according to any one of the preceding claims, characterized in that it further comprises adding a cationic organic polymer of low molecular weight to the suspension.

24.

 Process according to any one of the preceding claims, characterized in that it further comprises adding an anionic microparticle material selected from the group consisting of silica-based particles and smectite clays.

25.

Method according to any one of the preceding claims, characterized in that the suspension has a conductivity of at least 2.0 mS / cm.

26.

Method according to any one of the preceding claims, characterized in that it also comprises recycling white water and introducing 0 to 30 tons of fresh water per ton of paper produced.