KR20040068321A - Aqueous silica-containing composition and process for production of paper - Google Patents

Abstract

The present invention relates to an aqueous silica-containing composition comprising an anionic organic polymer having at least one aromatic group and anionic aggregated or microgel formed silica-based particles. The aqueous silica-containing composition contains the anionic organic polymer having at least one aromatic group and the anionic silica-based particles in an amount of at least 0.01 % by weight of the total weight of the aqueous silica-containing composition. The aqueous silica-containing composition contains substantially no cellulose-reactive sizing agent and the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulphonate formaldehyde condensate.The invention further relates to methods for the preparation of the aqueous silica-containing composition and the use of the aqueous silica-composition as a drainage and retention aid in a process for the production of paper. The invention also relates to a process for the production of paper from an aqueous suspension containing cellulosic fibres, and optionally filler, in which the aqueous silica-containing composition and at least one charged organic polymer are added to the cellulosic suspension.

Description

Aqueous Silica-Containing COMPOSITION AND PROCESS FOR PRODUCTION OF PAPER

In papermaking technology, a suspension containing aqueous cellulose fibers, and optionally fillers and additives, referred to as stock, is fed to a headbox which discharges the stock into a forming wire. Water is drained from the stock through the forming wires, forming a wet paper web on the wires. The formed paper web is dewatered and dried in the drying zone of the paper making machine. Drainage and retention aids are customarily introduced into stock to promote drainage and increase adsorption on cellulose fibers to retain fine particles with the fibers on the wire.

US Pat. No. 4,388,150 discloses a binder of papermaking comprising a composite of cationic starch and colloidal silicic acid to produce paper having increased strength and improved retention levels of added minerals and paper fines.

US Pat. No. 4,750,974 discloses coacervate binders for use in papermaking comprising tertiary combinations of cationic starch, anionic high molecular weight polymers and dispersed silica.

U.S. Patent 5,368,833 discloses a silica sol containing aluminum modified silica particles having a high specific surface area and a high content of microgels.

U. S. Patent 5,567, 277 discloses a composition comprising an anionic polymer comprising an aqueous cellulosic finish, a high molecular weight cationic polymer and a modified lignin.

US Pat. No. 6,022,449 discloses the use of anionic and / or potentially anionic groups and cationic and / or potentially cationic compounds and water-dispersed polyisocyanates in paper finishing.

EP 0 418 015 Al discloses an active sizing composition containing an aqueous emulsion in combination with an anionic dispersant or emulsifier. Using anionic polyacrylamide, anionic starch or colloidal silica, the anionic charge density of the sizing composition can be extended.

US Pat. No. 5,670,021 relates to a process for making paper by molding and dehydrating a suspension of cellulose. Dehydration here takes place in the presence of alkali metal silicates and phenolic resins added simultaneously to the suspension.

U. S. Patent No. 6,033, 524 discloses a method for increasing retention and drainage of filler components in the papermaking furnish of a papermaking process comprising the addition of slurry of filler component (also containing phenolic reinforcement) to the finish. do.

U. S. Patent No. 6,315, 824 relates to a dispersed composition comprising a hydrophobic phase and an aqueous phase. The composition is stabilized by a cationic colloidal coacervate stabilizer, which comprises an anionic component and a cationic component.

EP 0,953,680 Al relates to a process for the production of paper from suspensions which comprises the addition of cationic organic polymers to the suspensions.

US Pat. No. 5,185,062 discloses a papermaking process comprising adding a high molecular weight cationic polymer to the papermaking component and then adding a medium molecular weight anionic polymer.

U. S. Patent No. 4,313, 790 relates to a process for the manufacture of paper consisting of the addition of kraft lignin or modified kraft lignin and poly (oxyethylene) to paper furnishes.

U. S. Patent No. 6,165, 259 relates to an aqueous dispersion containing a dispersant and a disperse phase containing a hydrophobic material. This dispersant includes anionic compounds and cationic compounds.

It would be beneficial to provide improved performance drainage and retention aids. It would also be beneficial to provide retention and drainage aids with good storage stability. Furthermore, it would be beneficial to provide a papermaking process with improved drainage and / or retention performance.

The present invention relates to an aqueous silica-containing composition comprising an anionic organic polymer having at least one aromatic group and anionic silica-based particles. The invention also relates to a process for preparing the aqueous silica-containing composition, the use of the aqueous silica-containing composition and the papermaking process.

According to the present invention, improved drainage of cellulosic suspensions on a wire by using an aqueous silica-containing composition comprising at least one anionic organic polymer having at least one aromatic group and an anionic aggregated or microgel formed silica-based particle And / or it has been surprisingly found that a retention effect can be obtained. Aqueous silica-containing compositions are useful for paper manufacturing processes from all types of stocks, especially stocks having high content of salts (high conductivity) and colloidal materials. Aqueous silica-containing compositions are also useful in papermaking processes with high white water closure, ie extended white water recycling and limited fresh water supply. The present invention here makes it possible to increase the speed of the papermaking machine and to use low dose additives to provide a corresponding drainage and / or retention effect. This leads to improved papermaking processes and economic benefits.

As used herein, the term "drainage and retention aid", when added to an aqueous cellulosic suspension, provides one or more components that provide better drainage and / or retention compared to the absence of the addition of one or more components. Means. All types of stocks, especially those with high salt (high conductivity) and colloidal materials, will obtain better drainage and retention performance by the addition of the composition according to the invention. Improved drainage and retention performance is important in the papermaking process, for example in processes with a high degree of white water closure, ie extensive white water recycling and limited fresh water supply.

According to the present invention there is provided an aqueous silica containing composition comprising an anionic organic polymer having at least one aromatic group and an anionic silica-based particle comprising aggregated or microgel forming silica-based particles. The aqueous silica-containing composition contains an anionic organic polymer having at least 0.01% by weight of at least one aromatic group based on the total weight of the aqueous silica-containing composition and anionic silica-based particles calculated as SiO ₂ . The composition is substantially free of cellulose-reactive sizing agents and the anionic organic polymer is not an anionic naphthalene sulfonate formaldehyde condensate.

In addition, anionic organic polymers having at least one aromatic group may be prepared with an aqueous alkali stabilized silica-based sol having an S-value from about 5 to about 50% and containing anionic aggregated or microgel-formed silica-based particles. There is provided an aqueous silica-containing composition obtainable by mixing. The resulting aqueous silica-containing composition contains anionic organic polymer having at least one aromatic group and silica-based particles calculated as SiO ₂ in a capacity of at least 0.01% by weight based on the total weight of the aqueous silica containing composition. The composition is substantially free of cellulose-reactive sizing agents and the anionic organic polymer is not an anionic naphthalene sulfonate formaldehyde condensate.

In addition, silica-calculated as SiO ₂ in an amount of at least 0.01% based on the total weight of the aqueous silica-containing composition, provided that the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulfonate formaldehyde condensate. Anionic organic polymers having at least one aromatic group in the absence of a cellulose-reactive sizing agent are provided in an anionic manner to provide an aqueous silica-containing composition containing the basic particles and an anionic organic polymer having at least one aromatic group. Or a process for producing an aqueous silica containing composition comprising mixing with silica-based particles comprising microgel formed silica based particles.

Further, silica- calculated as SiO ₂ by weight of 0.01% or more based on the total weight of the aqueous silica-containing composition, provided that the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulfonate formaldehyde condensate. To provide an aqueous silica-containing composition containing the basic particles and an anionic organic polymer having at least one aromatic group, anionic organic polymers having at least 0.1 meq / g of charge density of the dry polymer and at least one aromatic group are anionic. A process for the preparation of an aqueous silica containing composition comprising mixing with silica-based particles comprising aggregated or microgel formed is provided.

And anion having at least one aromatic group by weight of at least 0.01% based on the total weight of the aqueous silica-containing composition, provided that the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulfonate formaldehyde condensate. Desalting and desalting an aqueous solution of anionic organic polymer having at least one aromatic group to provide an aqueous silica-containing composition containing the polymeric organic polymer and the silica-based particles calculated as aggregated or microgel formed SiO ₂ . A method of making an aqueous silica containing composition is provided comprising mixing an anionic organic polymer having at least one aromatic group with a silica based particle comprising anionic aggregated or microgel formed silica-based particles.

There is also provided an aqueous silica-containing composition obtainable by the process according to the invention.

The present invention also relates to the use of the aqueous silica-containing compositions of the invention used as flocculants in combination with one or more cationic organic polymers for the production of pulp and paper and for water purification.

According to the present invention there is provided a process for producing paper from suspensions containing cellulose fibers, and optionally fillers, comprising the addition of at least one cationic organic polymer and an aqueous silica containing composition according to the invention.

The aqueous silica-containing composition comprises at least one anionic organic polymer having at least one aromatic group. Wherein at least one aromatic group is not an anionic naphthalene sulfonate formaldehyde condensate. The aromatic group of the anionic polymer may be present in the polymer main chain or in a substituent group attached to the polymer main chain. Examples of suitable aromatic groups include aryl, aralkyl and alkaryl groups and derivatives thereof, such as phenyl, tolyl, naphthyl, phenylene, xylene, benzyl, phenylethyl and derivatives of these groups. The anion charged groups may be present as monomers used in the preparation of anionic polymers or anionic polymers. The anion charged group may be a group carrying an anionic charge or an acid group carrying an anionic charge when dissolved or dispersed in water. These groups are optionally indicated here with anionic groups such as phosphates, phosphonates, sulfates, sulfonic acids, sulfonates, carboxylic acids, carboxylates, alkoxides, and phenolic groups, ie hygioxy-substituted phenyl and naphthyl . Groups carrying anionic charge are usually salts of alkali, alkaline earth metal or ammonia.

Anionic polymers containing one or more aromatic groups according to the invention may suitably be selected from the group consisting of step-growth polymers, chain-growth polymers, polysaccharides and naturally occurring aromatic polymers. The term "step-growth polymer" as used herein refers to a polymer obtained by step-growth polymerization, and may also refer to a step-reaction polymer and a step-reaction polymerization, respectively. Preferably this anionic polymer is a step-growth polymer. The anionic polymers according to the invention may be linear, branched or crosslinked. Preferably this anionic polymer is water soluble or water-dispersible.

Examples of suitable anionic step-growth polymers according to the invention are condensation polymers, ie polymers obtained by step-growth condensation polymerization, for example with aldehydes such as formaldehyde and one or more anionic groups, and with urea and melamine Condensates with one or more aromatic compounds containing optional other co-monomers useful in the same condensation polymerization. Examples of suitable aromatic compounds containing anionic groups include, for example, phenolic compounds such as phenol, resorcinol and derivatives thereof and compounds containing anionic groups such as aromatic acids and their salts.

Examples of suitable anionic step-growth polymers according to the invention include anionic polyurethanes prepared from monomer mixtures comprising addition polymers, polymers obtained by step-growth addition polymerization, for example aromatic isocyanates and / or aromatic alcohols. Include. Examples of suitable aromatic isocyanates include diisocyanates such as toluene-2,4- and 2,6-diisocyanate and diphenylmethane-4,4'-diisocyanate. Examples of suitable aromatic alcohols include dihydric alcohols, ie diols such as bisphenol A, phenyl diethanol amine, glycerol monoterephthalate and trimethylolpropane monoterephthalate. Monohydric aromatic alcohols such as phenol and their derivatives are also used. This monomer mixture may also contain non-aromatic isocyanates and / or alcohols, usually diisocyanates and diols such as those known for use in the preparation of polyurethanes.

Examples of suitable monomers containing anionic groups, optionally and usually, are reactions with bases such as alkali and alkaline earth metal metal hydroxides, for example sodium hydroxide, ammonia or amines, for example triethylamine. Together (this forms alkali, alkaline earth metal or ammonium counter ions), glycerol monosuccinate, glycerol monoterephthalate, trimethylolpropane monosuccinate, trimethylolpropane monoterephthalate, N, N-bis- (hydroxy Triols, for example trimethylolethane, trimethylolpropane and glycerol, for example succinic acid, such as ethyl) -glycine, di- (hydroxymethyl) propionic acid, NN-bis- (hydroxyethyl) aminoethanesulfonic acid And of dicarboxylic acids or their anhydrides such as anhydrides, terephthalic acid and anhydrides Monoester reaction products.

Examples of suitable anionic chain-grown polymers according to the present invention include anionic vinyl addition polymers obtained from mixtures of monomers unsaturated with vinyl or ethylene. Mixtures of monomers unsaturated with vinyl or ethylene include one or more monomers having aromatic groups and one or more monomers having anionic groups. Usually this monomer is co-polymerized with non-ionic monomers such as acrylate- and acrylamide-based monomers. Suitable anionic monomers include (meth) acrylic acid and paravinyl phenol (hydroxy styrene).

Examples of suitable anionic polysaccharides having one or more aromatic groups include starch, guar gum, cellulose derivatives, chitin, chitosan, glycan, galactan, glucan, xanthan gum, pectin, mannan, dextrin, preferably starch, And guar gum, suitable starches include potatoes, corn, wheat, tapioca, rice, bare corn and barley, preferably potatoes. The anionic groups of the polysaccharides can be inherent and / or introduced by chemical treatment. Aromatic groups of polysaccharides can be introduced by methods known in the art.

Examples of suitable- (modified) naturally occurring aromatic anionic polymers of the present invention are lignosulfonates, kraft lignin, oxylignin, and tannin extracts, ie from sulfite or sulphate pulp processes or bark extracts. Natural polyphenolic substances obtained from.

The average molecular weight of the anionic polymer can vary widely, especially depending on the type of polymer used, and is usually at least about 500, suitably at least about 800 and preferably at least about 1,000. The upper limit is not critical; It is about 10,000,000, usually 1,000,000, suitably 500,000, preferably 200,000 and most preferably 100,000.

These anionic polymers can have a wide variety of degrees of anionic substitution (DS _A ), in particular depending on the type of polymer used. DS _A 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 (DS _Q ) is 0.001 to 1.0, usually 0.01 to 0.8, suitably 0.02 to 0.7 and preferably 0.025 to 0.5. For anionic polymers containing cationic groups, the degree of cationic substitution (DS _c ) is, for example, 0 to 0.2, suitably 0 to 0.1 and preferably 0 to 0.05, and the anionic polymer It holds the total anionic charge. Usually the anionic charge of this anionic polymer is 0.1 to 10.0 meq / g, suitably 0.2 to 6.0 meq / g, and preferably 0.5 to 4.0 meq / g of the dry polymer.

The aqueous silica-containing compositions according to the invention also contain anionic aggregated or microgel-formed silica-based particles, ie particles based on SiO ₂ , preferably particles formed by polymerization of silicic acid comprising both homopolymers and copolymers. It includes. Optionally these silica-based particles can be modified and contain other elements, such as amines, aluminum and / or boron, which may be present in the aqueous phase and / or silica-based particles.

Examples of suitable aggregated or microgel formed silica-based particles include colloidal silica, colloidal aluminum-modified silica or aluminum silicate, and other types of polysilicates and mixtures thereof alone or in other types of anionic silica-based particles. Include with. In the art, polysilicates are also referred to as polymeric silicic acids, polysilicate microgels, polysilicates and polysilicate microgels. These are all encompassed by the term polysilicate used herein. These types of aluminum-containing compounds are commonly referred to as polyaluminosilicates and polyaluminosilicate microgels, including colloidal aluminum-modified silica and aluminum silicates.

Anionic silica-based particles are particle sizes in the colloidal range. Particles small enough to not be affected by this state of gravity but large enough to exhibit no significant deviation from the properties of a typical solution. That is, the average particle size is significantly less than 1 μm. This anionic silica-based particle is suitably about 50 nm or less, preferably about 20 nm or less and more preferably about 1 to about 50 nm, most preferably about 1 to about 10 nm in average particle size. Has In traditional silica chemistry, particle size dictates the average size of the aggregated or non-aggregated primary particles. Suitably, the silica-based particles of the aqueous silica-containing composition of the present invention are optionally usually non-aggregated, or monodisperse, aggregated or microgel formed silica in combination with silica-based particles. Contains basic particles.

Suitably the silica-based particles have a specific surface area of greater than 50 m 2 / g, preferably greater than 100 m 2 / g. The specific surface area can be up to 1700 m 2 / g, preferably up to 1300 m 2 / g, usually from 300 to 1300 m 2 / g, preferably from 500 to 1050 m 2 / g. The specific surface area can be determined by titration with NaOH according to the methods disclosed in Sears, Analytical Chemistry 28 (1956), 12, 1981-1983 or US Pat. No. 5,176,891. The area given therefore represents the average specific surface area of the particles.

The total weight of the anionic organic polymer having at least one aromatic group contained in the aqueous silica-containing composition and the anionic silica-based particles calculated as SiO ₂ is at least 0.01% by weight relative to the total weight of the aqueous silica-containing composition. It is preferably at least 0.05% by weight, more preferably at least 0.1% by weight. Suitably the concentration of the anionic organic polymer having at least one aromatic group and the anionic silica-based particles calculated as SiO ₂ is from 1 to 45% by weight, preferably from 2 to 35% by weight, most preferably by weight 5 to 30%.

This aqueous silica-containing composition has an anionic charge density of at least 0.1 meq / g, with normal charges of 0.1 to 10 meq / g, suitably 0.1 to 8 meq / g, preferably 0.1 to 6 meq / g, and most Preferably it is within the range of 0.2-4 meq / g.

The aqueous silica-containing composition according to the invention is substantially free of cellulose-reactive sizing agents. Substantially up to 10% by weight, suitably less than 5%, and preferably less than 1% by weight, cellulose-reactive sizing agents are present in the aqueous silica-containing composition. Most preferably there is no cellulose-reactive sizing agent in the aqueous silica containing composition. Even more preferably, the sexy silica-containing composition according to the present invention is substantially free of sizing agent and suitably free of sizing agent.

The invention also relates to a process for the preparation of an aqueous-silica-containing composition. The two components are preferably stirred together. Anionic organic polymers having one or more aromatic groups can be added to the aqueous sol containing silica-based particles or silica-based particles can be added to the aqueous solution of anionic organic polymers having one or more aromatic groups. An aqueous solution of anionic organic polymer having at least one aromatic group is desalted or deionized. Desalting or deionization can be carried out by dialysis, membrane filtration, ultrafiltration, reverse osmosis or ion exchange or the like. Desalting or deionization is preferably carried out by ultra-filtration or dialysis. The pH of the aqueous solution of the anionic organic polymer will be adjusted to the pH of the silica-based particles before or after mixing the aqueous solution with the silica based particles. The pH may be adjusted to pH 8.0 or higher, suitably 9.0 or higher, preferably 9.5 or higher, preferably 9.0 to 11.O.

Anionic organic polymers having one or more aromatic groups mixed with silica-based particles have a charge density of dry polymer of at least 0.1 meq / g, usually 0.1 to 10.0 meq / g. Suitably 0.2 to 6.0 and preferably 0.5 to 4.

The preferably anionic silica-based particles mixed with the anionic organic polymer may have the aforementioned properties. Suitably this silica-based particle is contained in the sol. This sol has an S-value of 5 to 80%, suitably 5 to 50%, preferably 8 to 45%, and most preferably 10 to 30%. Calculation and measurement of S-values is described in Her & Dalton in J. Phys. Chem. 60 (1956), 955-957. S-values indicate the degree of aggregation or microgel formation, and lower S-values indicate a higher degree of aggregation.

Suitably, these silica-based particles optionally comprise aggregated or microgel formed silica-based particles, usually in combination with non-aggregated, or monodisperse, silica-based particles.

Suitably the silica based particles have a Si ₂ O: Na ₂ O molar ratio of less than 60, usually 5 to 60, and preferably 8 to 55.

The aqueous silica-containing composition obtained according to the method of the present invention is suitably anionic organic polymers and anionic silica-based particles having at least 0.01% of at least one aromatic group by weight calculated on the total weight of the aqueous silica-containing composition. Contains the total weight of. Preferably at least 0.05% by weight, more preferably at least 0.1% by weight. Suitably the concentration of the anionic organic polymer and the anionic silica-based particles having at least one aromatic group is from 1 to 45% by weight, preferably from 2 to 35% by weight, most preferably from 5 to 30% by weight. to be.

The products produced by these methods exhibit improved drainage and retention properties and also show better storage stability and therefore have a longer shelf life and therefore better drainage and retention assist performance on storage.

The mixing procedure of the aforementioned method is suitably carried out in the substantially absence of cellulose-reactive sizing agents. Substantially no more than 10% by weight, suitably less than 5%, preferably less than 1% by weight of cellulose-reactive sizing agents are present. Most preferably no cellulose reactive sizing agent is present. This mixing is carried out with substantially no sizing agent or no sizing agent.

The present invention also relates to a process for making paper from a suspension containing aqueous cellulose fibers. This process involves adding the cationic organic polymer and the aqueous silica-containing composition of the invention to the suspension. Cationic organic polymers according to the present invention may be in linear, branched or crosslinked form, and these preferred cationic polymers are water soluble or water-dispersible.

Examples of suitable cationic polymers include synthetic organic polymers such as step-growth polymers and chain-growth polymers, and polymers derived from natural raw materials such as, for example, polysaccharides.

Examples of suitable cationic synthetic organic polymers are vinyl addition polymers, such as acrylate- and acrylamide-based polymers, and cationic poly (diallyl dimethyl ammonium chloride), cationic polyethylene imines, cationic polyamines, polyamidoamines and vinyl Amide-based polymers, melamine-formaldehyde and urea-formaldehyde resins.

Examples of suitable polysaccharides include starch, guar gum, cellulose derivatives, chitin, chitosan, glycan, galactan, glucan, xanthan gum, pectin, mannan, dextrin, preferably starch and guar gum. Examples of suitable starches include potatoes, corn, wheat, tapioca, rice, waxy maize, barley, and the like.

Cationic starch and cationic acrylamide-based polymers are preferred polymers according to the present invention and they can be used alone or together or in combination with other polymers. Especially preferred are cationic acrylamide-based polymers having cationic starch and at least one aromatic group.

Cationic organic polymers may have one or more hydrophobic groups attached to them. Hydrophobic groups include aromatic groups, groups comprising aromatic groups or non-aromatic groups, preferably hydrophobic groups comprise aromatic groups. This hydrophobic group can be attached to a hetero atom such as, for example, nitrogen or oxygen, the nitrogen being selectively charged, which can then be attached to the main chain of the polymer, for example via a chain of atom. Can be. This hydrophobic group has at least 2 and usually at least 3 carbon atoms, suitably 3 to 12, and preferably 4 to 8 carbon atoms. This hydrophobic group is suitably a hydrocarbon chain.

Suitable dosages calculated based on the dry pulp of the cationic polymer of this system and the dry matter of the optional filler are from 0.01 to 50 kg / t [kg / tonne, "metric ton", preferably 0.1 To 30 kg / t and most preferably 1 to 15 kg / t.

Appropriate dosages considered on the basis of the dry pulp and the dry matter of the optional filler of the aforementioned aqueous silica-containing compositions of this system, calculated as anionic organic polymers having at least one aromatic group and anionic silica-based particles Is 0.01 to 15 kg / t, preferably 0.01 to 10 kg / t, most preferably 0.05 to 5 kg / t.

Suitable mineral fillers of the traditional type can be added to the aqueous cellulosic suspension according to the invention. Examples of suitable fillers include kaolin, kaolin, titanium dioxide, gypsum, talc and synthetic calcium carbonates such as natural and whistle, ground marble and precipitated calcium carbonate (PCC).

Moreover, for example, anionic trash catchers (ATC), wet strength agents, dry strength agents, optical brightening agents, dyes, aluminum compounds, etc. Traditional additives in papermaking can of course also be used in combination with the chemicals according to the invention. Examples of suitable aluminum compounds are alumina, aluminate, aluminum chloride, aluminum nitrate, and polyaluminum compounds such as polyaluminum chloride, polyaluminum sulfate, chloride and / or polyaluminum compounds containing sulphate ions, polyaluminum silicate sulfate And mixtures thereof. The polyaluminum compounds also contain other anions other than chloride ions, for example sulfuric acid, phosphoric acid, or anions of organic acids such as citric acid and oxalic acid. When aluminum compounds are applied in the process of the invention, they are usually added to the stock, preferably before the polymer component and the micro- or nano-particulate material. Appropriate levels of addition of the aluminum containing compound are at least 0.001 kg / t, preferably 0.01 to 5 kg / t, and more preferably 0.05 to 1 kg /, calculated as A1 ₂ 0 ₃ based on dry pulp and optional filler. t.

Examples of suitable anionic trace catchers include cationic polyamines, polymers or copolymers of quaternary amines, or aluminum containing compounds.

The process of the invention is used for the manufacture of paper. The term "paper" as used herein includes not only paper and paper products, but also other web-like products such as, for example, boards and paper boards, and their products. The invention is particularly useful for the production of paper having a gram of 150 g / m 2 or less, preferably 100 g / m 2 or less, such as, for example, fine paper, newspaper, low weight coated paper, super calender paper and tissues. Used.

This process can be used for the manufacture of paper from all types of stock containing and free of wood. Cellulose containing fibers and other types of suspensions of suspensions should suitably contain at least 25% by weight, and preferably at least 50% of such fibers, based on the dry matter. This suspension can be formulated from compatible or thermomechanical pulp, chemical-thermomechanical pulp, refiner such as wood-containing sulfate, sulfite and organosolv pulp from hardwood and softwood. refiner) Fibers from mechanical pulp, such as pulp and groundwood pulp, may also be based on recycled pulp, optionally de-inked pulp, and mixtures thereof. Preferably the stock is a wood-containing stock which has a high content of salt and is therefore highly conductive.

The chemicals according to the invention may be added to the aqueous cellulosic suspension, or stock, in the conventional manner and in any order. It is usually preferred to add the cationic polymer to the stock before adding the aqueous silica-containing composition. The reverse order of addition may also be used. More preferably, the cationic polymer is added before the shear step, which may be selected from pumping, mixing, cleaning, etc., and the aqueous silica-containing composition is added after the shear step.

This aqueous silica-containing composition can be used as flocculant in the treatment of water for the production of drinking water or in the environmental treatment of water, for example lakes. This composition can also be used as flocculant in the treatment of wastewater or waste sludge.

The invention is described in more detail below, but it is not intended to limit the scope of the invention. Unless stated otherwise, Parts and% refer to parts and weight percentages by weight, respectively, and all solutions are aqueous. The unit is meters.

Example 1

Drainage performance was measured by DDA (Dynamic drainage Analyser) of Akribi, Sweden. Drainage time was measured for a defined volume of stock through the wire when the plug was removed and a vacuum was provided opposite where the wire was in stock.

Retention performance was evaluated by measuring the turbidity of the filtrate, white water, obtained by draining the stock by a nephelometer. Turbidity was measured in NTU (nephelometric turbidity Units).

The test stock contained wood, pH 7.2, the conductivity of the stock was 5.0 mS / cm, and the concentration was 1.42 g / l. The stock was stirred at a speed of 1500 rpm throughout the test in a baffled jar.

In the examples, the cationic polymer was added to the stock before the aqueous composition or anionic control according to the invention. This cationic polymer was cationic starch (Cl) obtained by quarternisation of native potato starch with 0.5% N of 3-chloro hydroxypropyl dimethyl benzyl ammonium chloride and stirred for 45 seconds after addition, then negative The warm aqueous composition was added and stirred for 15 seconds before draining.

An aqueous composition containing anionic polyurethane and colloidal silica according to the present invention was measured to evaluate their drainage and retention performance. All samples were diluted to 0.5% solids before assessing drainage properties. Anionic polyurethanes (P 1) are based on 15% solids of anionic polyurethanes prepared from glyceryl monostearate (GMS) and toluolyl diisocyanate (TDI). This forms a pre-polymer, which reacts with dimethylolpropionic acid (DMPA) so that 30 mol% of GMS is replaced with DPMA / N-methyl diethanol amine (N-MDEA). Colloidal silica sol (S 1) is of the type disclosed in US Pat. No. 5,447,604 and has a molar ratio of 10 molar ratio of SiO ₂ : Na ₂ O, a specific surface area of 870 m 2 / g, 35% S-value and 10.0% by weight of silica. Have The drainage time of the stock with 20 kg / t of C1 was 29 seconds and the turbidity measured was 44 NTU. All additions were calculated on the dry stock as dry matter. Drainage times measured from the distinct additions of the aqueous composition stock of the present invention are summarized in Table 1.

Table 1

The drainage time and turbidity of the compositions S1 / P1 indicate that when two components (S1 and Pl) are added as a composition they have a synergistic improvement in drainage and retention performance.

Example 2

The drainage and retention performance of the containing aqueous composition according to the invention was evaluated. The composition contains an anionic polyurethane (P2) based on 19% solid anionic polyurethane made from TDI and phenyl diethanoiamine amine PDEA, which produces a pre-polymer and the prepolymers are DMPA and N-MDEA In reaction with 30 mol% of PEDA is replaced by DPMA / NMIDEA. And the composition contains colloidal silica (S2) having a molar ratio of mole ratio SiO ₂ : Na ₂ O of 20, a specific surface area of 700 m 2 / g, an S-value of 32% and 15.0%. All samples were diluted to 0.5% solids prior to drainage and retention evaluation, and the evaluation was performed in the same manner as in Example 1 and using the same cationic starch in the same stock. The drainage time measured for the stock with 20 kg / t of C 1 was 27 seconds and the turbidity was measured at 45 NTU. All additions were calculated dry on the dry stock. Drainage times determined from the distinct additions to the aqueous composition stock of the present invention are summarized in Table 2.

TABLE 2

Example 3

In this example the test stock was an SC-finished paper (finished paper for Super Calandered paper), pH 7.6, conductivity of the stock 0.5 mS / cm, and concentration 1,49 g / l. The stock was stirred at a speed of 1500 rpm throughout the test in a baffled jar. C 1 was added to the stock at a dose of 20 kg / t (kg / tonne) in each test. The drainage time of the stock containing no additives was 30 seconds and the turbidity was 98 NTU. The drainage time of the stock containing only C 1 was 14.8 seconds and the turbidity was 52 NTU. The anionic polyurethane used in this example was a 15% solid anionic polyurethane (P3), made from GMS and TDI, which forms a pre-polymer, which reacts with DMPA. And colloidal silica (S3) disclosed in US Pat. No. 5,368,833 was a silica sol, having a molar ratio of SiO ₂ : Na ₂ O 45, a specific surface area of 850 m 2 / g, an S-value of 20% and a silica content of 8.0%, and Aluminum was transformed into 0.3% A1203.

The performance of the aqueous compositions according to the invention was compared with that of the individually added ingredients. In all tests C1 was stirred for 45 seconds after addition to the stock, after which the composition S3 / P3 was added and stirred for 15 seconds. When the components were added separately, the first component was added and stirred for 30 seconds, after which the second component was added and stirred for 15 seconds. All additions were calculated as dry to dry stock. Drainage times measured from the distinct additions to the stock are summarized in Table 3.

TABLE 3

Example 4

The drainage and retention performance of the aqueous composition according to the invention was evaluated. This aqueous composition has a weight of 89.0% dry matter, pH 10.5, sodium content 9.5%, and total sulfur content of 5.4%, where sulfur is a sulfonated and carboxylated kraft lignin derived from 4.2% bound softwood. Fermented fir containing 10% solution of anionic lignosulfonate (LSI), the sodium salt of Kraft lignin, or 93.0% by weight of dry matter, pH 8.5, 8% sodium, and 3% sulfur It contains 10% solution anionic lignosulfonate (LS2) which is sodium oxylignin derived from wood sulfite liquor. And this composition contains colloidal silica S1. All were diluted to 0.5% solids before drainage assessment. The drainage time of the stock with 20 kg / t of C 1 was measured at 29 seconds and the turbidity was measured at 44 NTU. All additions were calculated as dry matter for the dry stock. The drainage times measured from the distinct additions of the stocks of the aqueous compositions of the present invention are summarized in Table 4.

Table 4

Claims (20)

At least 0.01% by weight, based on the total weight of the aqueous silica-containing composition, comprising anionic organic polymers having at least one aromatic group and anionic silica-based particles comprising aggregated or microgel formed silica-based particles. Containing anionic organic polymers having at least one aromatic group in capacity and silica-based particles calculated as anionic SiO ₂ , the composition being substantially free of cellulose-reactive sizing agents and having at least one aromatic group An aqueous silica-containing composition, provided the polymer is not an anionic naphthalene sulfonate formaldehyde condensate. Provided that the composition is substantially free of cellulose reactive sizing agents and the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulfonate formaldehyde condensate, and an anionic organic polymer having at least one aromatic group and To provide an aqueous silica-containing composition containing silica-based particles calculated as SiO ₂ in a capacity of at least 0.01% by weight based on the total weight of the aqueous silica-containing composition, an anionic organic polymer having at least one aromatic group. An aqueous silica-containing composition obtainable by mixing with an aqueous alkali stabilized silica-based sol having an S-value from about 5 to about 50% and containing anionic aggregated or microgel formed silica-based particles. Provided that the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulfonate formaldehyde condensate, and based on the total weight of the aqueous silica-containing composition, To provide an aqueous silica-containing composition containing an anionic organic polymer having and silica-based particles calculated as SiO ₂ , an anionic organic having at least one aromatic group in the substantially absence of a cellulose-reactive-sizing agent A method of making an aqueous silica-containing composition comprising mixing a polymer with silica-based particles comprising anionic aggregated or microgel formed silica-based particles. Provided that the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulfonate formaldehyde condensate, and based on the total weight of the aqueous silica-containing composition, In order to provide an aqueous silica-containing composition containing an anionic organic polymer having and silica-based particles calculated as SiO ₂ , an anionic organic polymer having a charge density of at least 0.1 meq / g of a dry polymer and at least one aromatic group A method of making an aqueous silica-containing composition comprising mixing with anionic silica-based particles comprising aggregated or microgel formed silica-based particles. Provided that the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulfonate formaldehyde condensate, and based on the total weight of the aqueous silica-containing composition, In order to provide an aqueous silica-containing composition containing an anionic organic polymer having and silica based particles calculated as SiO ₂ , the aqueous solution of the anionic organic polymer having at least one aromatic group is desalted and the at least one aromatic group is desalted. A method of making an aqueous silica-containing composition comprising mixing an anionic organic polymer comprising an anionic silica-based particle comprising aggregated or microgel formed silica-based particles. The aqueous according to any one of claims 3 to 5, wherein the silica-based particles are contained in a silica sol having an S-value of up to 5-50% before being mixed with an anionic organic polymer having at least one aromatic group. Method of Making Silica-Containing Compositions. The method of claim 1, wherein the anionic organic polymer having at least one aromatic group is desalted prior to mixing with the silica-based particles. 8. A process for preparing the aqueous silica-containing composition of claims 1 or 2, or the aqueous silica-containing composition according to claims 3 to 7, wherein the silica-based particles have a specific surface area of 300 to 1300 m 2 / g. Aqueous Silica-Containing Compositions or Methods of Making Aqueous Silica-containing Compositions. 9. The process for preparing the aqueous silica-containing composition of claims 1, 2 or 8, or the aqueous silica-containing composition according to claims 3-8, wherein the silica-based particles are from about 1 nm to about 50 nm. A process for preparing an aqueous silica-containing composition or an aqueous silica-containing composition having an average particle size up to. 10. The process for preparing the aqueous silica-containing composition of claim 1, 2, 8 or 9, or the aqueous silica-containing composition according to claim 3, wherein the silica-based particles are about 1 nm. A method of making an aqueous silica-containing composition or aqueous silica-containing composition having an average particle size from about 10 nm. 11. A process for preparing the aqueous silica-containing compositions of claims 1, 2, 8, 9 or 10, or the aqueous silica-containing compositions according to claims 3 to 10, wherein at least one aromatic group Wherein the pH of the aqueous solution of anionic organic polymer having is adjusted to at least 8 prior to mixing with the silica-based particles or a process for producing an aqueous silica-containing composition. 12. A process for preparing the aqueous silica-containing composition of claims 1, 2, 8, 9, 10 or 11, or the aqueous silica-containing composition according to claims 3 to 11. Anionic organic polymers having at least one aromatic group are polyurethanes, lignosulfonates, kraft lignin or oxylignin. A process for preparing an aqueous silica-containing composition or an aqueous silica-containing composition. The preparation of the aqueous silica-containing composition of claim 1, 2, 8, 9, 10, 11, or 12, or the aqueous silica-containing composition according to claim 3. The process of claim 1, wherein the aqueous silica-containing composition has an aqueous silica-containing composition or aqueous silica-containing composition having a negative charge density of 0.1 to 6 meq / g. An aqueous silica-containing composition obtainable by the process according to any one of claims 3 to 13. Claims 1, 2, 8, 9, 10, 11, 12 and 12, used as flocculants together with one or more organic polymers for the production of pulp and paper and for water purification. Use of an aqueous silica-containing composition according to claim 13. At least one cationic organic polymer in suspension and according to any one of claims 1, 2, 8, 9, 10, 11, 12, 13 or 14 Process for preparing paper from suspension containing cellulose fibers, and optionally filler, comprising the addition of an aqueous silica-containing composition or an aqueous silica-containing composition obtainable by the method according to any one of claims 3 to 11. . 15. The process of claim 14 wherein the cationic organic polymer is cationic starch or cationic polyacrylamide. The process of claim 14 or 15 wherein the cationic organic polymer has at least one aromatic group. The aqueous silyl-containing composition according to claim 1 or 2, wherein the composition is substantially free of sizing agents. The process of claim 3, wherein the mixing is carried out in the substantially absence of a sizing agent.