EP1456469A1 - Aqueous silica-containing composition and process for production of paper - Google Patents

Aqueous silica-containing composition and process for production of paper

Info

Publication number
EP1456469A1
EP1456469A1 EP02793739A EP02793739A EP1456469A1 EP 1456469 A1 EP1456469 A1 EP 1456469A1 EP 02793739 A EP02793739 A EP 02793739A EP 02793739 A EP02793739 A EP 02793739A EP 1456469 A1 EP1456469 A1 EP 1456469A1
Authority
EP
European Patent Office
Prior art keywords
silica
formaldehyde condensate
aqueous
based particles
anionic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP02793739A
Other languages
German (de)
French (fr)
Other versions
EP1456469B1 (en
Inventor
Johan Nyander
Hans Johansson-Vestin
Jan Nordin
Annika Viola Pal
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Akzo Nobel NV
Nouryon Pulp and Performance Chemicals AB
Original Assignee
Akzo Nobel NV
Eka Chemicals AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Akzo Nobel NV, Eka Chemicals AB filed Critical Akzo Nobel NV
Priority to EP02793739.0A priority Critical patent/EP1456469B1/en
Publication of EP1456469A1 publication Critical patent/EP1456469A1/en
Application granted granted Critical
Publication of EP1456469B1 publication Critical patent/EP1456469B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H3/00—Paper or cardboard prepared by adding substances to the pulp or to the formed web on the paper-making machine and by applying substances to finished paper or cardboard (on the paper-making machine), also when the intention is to impregnate at least a part of the paper body
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/71—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes
    • D21H17/74—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes of organic and inorganic material
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
    • D21H13/36—Inorganic fibres or flakes
    • D21H13/38—Inorganic fibres or flakes siliceous
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
    • D21H17/24—Polysaccharides
    • D21H17/28—Starch
    • D21H17/29—Starch cationic
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/33—Synthetic macromolecular compounds
    • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
    • D21H17/375—Poly(meth)acrylamide
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/33—Synthetic macromolecular compounds
    • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
    • D21H17/44—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
    • D21H17/45—Nitrogen-containing groups
    • D21H17/455—Nitrogen-containing groups comprising tertiary amine or being at least partially quaternised
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/33—Synthetic macromolecular compounds
    • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/47—Condensation polymers of aldehydes or ketones
    • D21H17/48—Condensation polymers of aldehydes or ketones with phenols
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
    • D21H17/68—Water-insoluble compounds, e.g. fillers, pigments siliceous, e.g. clays
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/06—Paper forming aids
    • D21H21/10—Retention agents or drainage improvers

Definitions

  • Aqueous silica-containing composition and process for production of paper are Aqueous silica-containing composition and process for production of paper
  • the present invention relates to a process for the production of paper from a suspension containing cellulosic fibres, comprising adding at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles.
  • the invention further relates to an aqueous silica-containing composition and methods for the preparation of the aqueous silica-containing composition, and uses of the aqueous silica- containing composition.
  • an aqueous suspension containing cellulosic fibres, and optionally fillers and additives, referred to as stock is fed into a headbox which ejects the stock onto a forming wire. Water is drained from the stock through the forming wire, so that a wet web of paper is formed and dewatered on the ire. The paper web is then dried in the drying section of the paper machine. Drainage and retention aids are conventionally introduced into the stock in order to facilitate drainage and to increase adsorption of fine particles onto the cellulosic fibres to retain them with the fibres on the wire.
  • US 4,388,150 discloses a binder in papermaking comprising a complex of cationic starch and colloidal silicic acid to produce a paper having increased strength and improved levels of retention of added minerals and papermaking fines.
  • US 4,750,974 discloses a coarcervate binder for use in papermaking comprising a tertiary combination of a cationic starch, an anionic high molecular weight polymer and a dispersed silica.
  • US 5,368,833 discloses silica sols containing aluminium modified silica particles with high specific surface area and a high content of microgel.
  • EP 0 418 015 A1 discloses an active sizing composition containing an aqueous emulsion in combination with an anionic dispersant or emulsifier.
  • anionic polyacrylamide, anionic starch or colloidal silica By using anionic polyacrylamide, anionic starch or colloidal silica the anionic charge density in the sizing composition can be extended.
  • US 4,443,496 refers to a method for modifying a surface layer of handened cement or substrates with use of the agent which comprises in a specified ratio of an alkali silicate solution and a sodium naphthalene sulphonate formaldehyde condensate.
  • US 4,559,241 relates to an aqueous solution of alkali metal silicate and nitrite. The solution may also contain additives such as formaldehyde condensate with naphthalene sulphonate.
  • US 5,595,629 refers to a papermaking process comprising adding to the slurry an anionic polymer and cationic polymer in order to increase retention and/or dewatering.
  • the anionic polymer comprises a formaldehyde condensate of naphthalene sulfonic acid salt with a molecular weight range of 500 to 120,000.
  • US 6,033,524 discloses a method for increasing retention and drainage of filling components in a paper making furnish in a paper making process comprising adding to the furnish a slurry of filling components, also containing a phenolic enhancer.
  • US 4,772,332 pertains to a heat stabilised slurry of bulked kaolin pigment which is prepared by mixing a water soluble cationic material with kaolin clay pigment in the presence of water.
  • US 5,733,414 relates to a process for manufacturing paper from a cellulosic suspension comprising adding a water soluble cationic polymer and a water soluble formaldehyde condensate resin.
  • US 5,1 0414 discloses a procedure for manufacturing lignocellulosic material products and improving their strength and water resistant characteristics, high molar mass lignin derivatives being added to the material.
  • the Invention it has unexpectedly been found that an improved drainage and/or retention effect of a cellulosic suspension on a wire can be obtained by using an aqueous silica-containing composition comprising anionic naphthalene sulphonate formaldehyde condensate and silica-based particles.
  • the present invention makes it possible to increase the speed of the paper machine and to use a lower dosage of additives to give a corresponding drainage and/or retention effect, thereby leading to an improved papermaking process and economic benefits.
  • drainage and retention aid refer to one or more components, which when added to an aqueous cellulosic suspension, give better drainage and/or retention than obtained when not adding the said one or more components.
  • AH types of stocks in particular stocks having high contents of salts (high conductivity) and colloidal substances will obtain better drainage and retention performances by the addition of the composition according to the present invention.
  • Improved drainage and retention performances are important in papermaking processes for instance in processes with a high degree of white water closure, i.e. extensive white water recycling and limited fresh water supply.
  • a process for the production of paper from a suspension containing cellulosic fibres, and optionally fillers comprising adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculated as SiO 2 ,within the range of from 0.2:1 to 99:1 , and containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO 2 , in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent.
  • an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles comprising aggregated or microgel formed silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculated as SiO 2 ⁇ within the range of from 0.2:1 to 99:1, and containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO 2 ,in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent.
  • an aqueous silica-containing composition obtainable by mixing anionic naphthalene sulphonate formaldehyde condensate with an aqueous alkali stabilised silica-based sol having an S-value in the range of from about 5 up to about 50% containing anionic aggregated or microgel formed silica-based particles, to provide an aqueous silica-containing composition containing an anionic naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO 2 , in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica-containing composition, with the proviso that the aqueous silica-containing composition contains substantially no cellulose-reactive sizing agent.
  • a method for preparation of an aqueous silica- containing composition which comprises mixing in the presence of substantially no cellulose-reactive sizing agent an anionic naphthalene sulphonate formaldehyde condensate with an aqueous alkali stabilised silica-based sol having an S-value in the range of from about 5 up to about 50% containing anionic aggregated or microgel formed silica-based particles to provide an aqueous silica-containing composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles within the range of from 0.2:1 to 99:1 , and containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO 2 , in an amount of at least 0.01 % by weight.
  • a method for preparation of an aqueous silica- containing composition which comprises mixing an aqueous anionic naphthalene sulphonate formaldehyde condensate solution having a conductivity less than 20 mS/cm with an aqueous alkali stabilised sol containing silica-based particles to provide an aqueous silica-containing composition containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO 2 , in an amount of at least 0.01 % by weight.
  • a method for preparation of an aqueous silica- containing composition which comprises desalinating of an aqueous anionic naphthalene sulphonate formaldehyde condensate solution, mixing the desalinated aqueous anionic naphthalene sulphonate formaldehyde condensate solution with an aqueous alkali stabilised sol containing silica-based particles to provide an aqueous silica-containing composition containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO 2 , in an amount of at least 0.01 % by weight.
  • a method for preparation of an aqueous silica- containing composition which comprises mixing in the presence of substantially no cellulose-reactive sizing agent an anionic naphthalene sulphonate formaldehyde condensate with an aqueous alkali stabilised silica-based sol having an S-value in the range of from about 5 up to about 50% containing anionic aggregated or microgel formed silica-based particles, to provide an aqueous silica-containing composition containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO 2 , in an amount of at least 0.01 % by weight
  • aqueous silica-containing composition obtainable by the methods according to the invention.
  • the invention further relates to the use of the aqueous silica-containing composition of the invention, as flocculating agent in the production of pulp and paper and for water purification.
  • the process for the production of paper according to the present invention comprises adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising anionic naphthalene sulfonate formaldehyde condensate and silica-based particles.
  • anionic naphthalene sulfonate formaldehyde condensate represent a group of polymers obtained by condensation polymerisation of formaldehyde with one or more naphthalene sulphonic acids or salts thereof.
  • the naphthalene sulfonate formaldehyde condensate may be reacted with a base, such as alkali metal and alkaline earth hydroxides, e.g. sodium hydroxide, ammonia or an amine, e.g. triethylamine, thereby forming an alkali metal, alkaline earth or ammonium counter-ion.
  • a base such as alkali metal and alkaline earth hydroxides, e.g. sodium hydroxide, ammonia or an amine, e.g. triethylamine
  • the anionic naphthalene sulfonate formaldehyde condensate has a molecular weight of at least about 500, suitably from about 1,000.
  • the upper limit is not critical it can be up to 1,000,000, usually up to 300,000, suitably up to 150,000 and preferably up to 60,000.
  • the aqueous silica-containing composition used in the process according to the invention also comprises anionic silica-based particles i.e. particles based on SiO 2 , preferably formed by polymerising silicic acid, encompassing both hornopolyiners and copolymers.
  • the silica-based particles can be modified and contain other elements, e.g. amine, aluminium and/or boron, which can be present in the aqueous phase and/or in the silica-based particles.
  • silica-based particles examples include colloidal silica, colloidal aluminium-modified silica or aluminium silicate, and different types of polysilicic acid and mixtures thereof, either alone or in combination with other types of anionic silica-based particles.
  • polysilicic acid is also referred to as polymeric silicic acid, polysilicic acid microgel, polysilicate and polysilicate microgel, which are all encompassed by the term polysilicic acid used herein.
  • Aluminium-containing compounds of this type are commonly referred to as polyaluminosilicate and polyaluminosilicate microgel including colloidal alumi- nium-modified silica and aluminium silicate.
  • the anionic silica-based particles are in the colloidal range of particle size, i.e. colloidal silica-based particles.
  • This colloidal state comprises particles sufficiently small not to be affected by gravitational forces but sufficiently large not to show marked deviation from the properties of typical solutions, i.e. average particle size significantly less than 1 ⁇ m.
  • the anionic silica-based particles have an average particle size suitably below about 50 nm, preferably below about 20 nm and more preferably in the range of from about 1 to about 50 nm, most preferably from about 1 nm up to about 10 nm.
  • the particle size refers to the average size of the primary particles, which may be aggregated or non-aggregated.
  • the silica-based particles present in the aqueous silica-containing composition of the invention comprise aggregated or microgel formed silica-based particles, optionally and usually in combination with non-aggregated, or monodisperse, silica-based particles.
  • the silica-based particles have a specific surface area larger than 50 m 2 /g, preferably larger than 100 m 2 /g.
  • the specific surface area can be up to 1700 m 2 /g, preferably up to 1300 m 2 /g, and usually within the range from 300 to 1300 m 2 /g, preferably from 500 to 1050 m 2 /g.
  • the specific surface area can be measured by means of titration with NaOH according to the method described by Sears, Analytical Chemistry 28(1956), 12, 1981-1983 or in U.S. Patent No. 5,176,891.
  • the given area thus represents the average specific surface area of the particles.
  • the aqueous silica-containing composition used in the process according to the invention may have a weight ratio of anionic naphthalene sulphonate formaldehyde condensate to anionic silica-based particles, calculated asSiO 2 , within the range of from 0.2:1 to 99:1 , suitably from 0.2:1 to 90:1 , preferably from 0.25:1 to 85:1.
  • the total weight of the anionic naphthalene sulphonate formaldehyde condensate and anionic silica- based particles, calculated as SiO 2, contained in the aqueous silica-containing uui ⁇ ubiii ⁇ n is Si itsaSi u.u i vo uy wtsiym, Caiuuiaicu un u ic ULSI wciy ⁇ i ⁇ i u ic ⁇ j uc ⁇ uS silica-containing composition, suitably the concentration of anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, calculated as SiO 2
  • the aqueous silica-containing composition can have an anionic charge density of at least 0.1 meq/g, usually the charge is within the range of 0.1 to 6 meq/g, suitably within the range of 0.1 to 5 meq/g, preferably within the range of 0.2 to 4 meq/g, and most preferably of 0.2 to 3.5 meq/g.
  • the aqueous silica-containing composition according to the invention contains substantially no cellulose-reactive sizing agent.
  • substantially no means that less or equal to 10% by weight, suitably less than 5%, preferably less than 1% by weight of cellulose-reactive sizing agent is present in the aqueous silica-containing composition. Most preferably there is no cellulose-reactive sizing agent in the aqueous silica- containing composition.
  • the aqueous silica-containing composition contains substantially no nitrites.
  • substantially no means that less or equal to 10% by weight, suitably less than 5%, preferably less than 1% by weight of nitrites is present in the aqueous silica-containing composition.
  • nitrites encompass all nitrites such as nitrites of ammonium, lithium, kalium, sodium, calcium, and magnesium.
  • the present invention relates further to a method for preparation an aqueous silica-containing composition.
  • the two components are preferably stirred together.
  • the anionic naphthalene sulfonate formaldehyde condensate can be added to an aqueous sol containing the silica-based particles or the silica-based particles can be added to an aqueous solution of naphthalene sulfonate formaldehyde condensate.
  • the aqueous solution of anionic naphthalene sulfonate formaldehyde condensate may be desalinated or deionisated.
  • the desalination or deionisation can be carried out with dialysis, membrane filtration, ultra-filtration, reversed osmosis or ion exchange or the like. It is preferred that the desalination or deionisation is carried out by the use of ultra-filtration or dialysis.
  • the anionic naphthalene sulfonate formaldehyde condensate to be mixed with the silica-based particles has the previously mentioned properties and has a conductivity less than 30 mS/cm, suitable less than 25 mS/cm, preferably less than 20 mS/cm, and most preferably less than 15 mS/cm measured at an anionic naphthalene sulfonate formaldehyde condensate content of 10%.
  • the conductivity is usually at least 1 mS/cm, suitably at least 3 mS/cm and preferably within the range of from 5 to 15 mS/cm, measured at an anionic naphthalene sulfonate formaldehyde condensate content of 10%.
  • the silica-based particles preferably anionic, to be mixed with anionic naphthalene sulfonate formaldehyde condensate have the previously mentioned properties.
  • the silica-based particles are contained in a sol, preferably alkali stabilised, before mixing with anionic naphthalene sulfonate formaldehyde condensate.
  • the sol may have an S-value in the range of from 5 to 50%, preferably from 8 to 45%, and most preferably from 10 to 30%. Calculation and measuring of the S-value can be performed as described by Her & Dalton in J. Phys. Chem. 60(1956), 955-957.
  • the S-value indicates the degree of aggregate or microgel formation and a lower S-value is indicative of a higher degree of aggregation.
  • the silica-based particles comprise aggregated or microgel formed silica-based particles, optionally and usually in combination with non- aggregated, or monodisperse, silica-based particles.
  • the silica-based particles have a molar ratio Si 2 O:Na 2 O less than 60, usually within the range 5 to 60, and preferably within the range from 8 to 55.
  • the anionic naphthalene sulphonate formaldehyde condensate is usually mixed with silica-based particles in a weight ratio within a range of from 0.2:1 to 99:1 , suitably from 0.2:1 to 90:1 , preferably from 0.25:1 to 85:1.
  • the products prepared by any of these methods exhibits an improved storage stability and therefore a better drainage and retention aid performance when stored.
  • the mixing procedure of above mention methods is suitably carried out in the presence of substantially no cellulose-reactive sizing agent.
  • substantially no means that less or equal to 10% by weight, suitably less than 5%, preferably less than 1% by weight of cellulose-reactive sizing agent is present. Most preferably there is no cellulose- reactive sizing agent present.
  • the present invention further relates to a process for the production of paper from an aqueous suspension containing cellulosic fibres.
  • the process comprises adding to the suspension a cationic organic polymer and the aqueous silica-containing composition of the invention.
  • the cationic organic polymer according to the invention can be linear, branched or cross-linked.
  • Preferably the cationic polymer is water-soluble or water-dispersible.
  • suitable cationic polymers include synthetic organic polymers, e.g. step-growth polymers and chain-growth polymers, and polymers derived from natural sources, e.g. polysaccharides.
  • Suitable cationic synthetic organic polymers include vinyl addition polymers such as acrylate- and acrylarnide-based polymers, as well as cationic poly(diallyl dimethyl ammonium chloride), cationic polyethylene imines, cationic polyamines, polyamidoamines and vinylamide-based polymers, melamine-formaldehyde and urea-formaldehyde resins.
  • suitable polysaccharides include starches, guar gums, celluloses, chitins, chitosans, glycans, galactans, glucans, xanthan gums, pectins, mannans, dextrins, preferably starches and guar gums.
  • suitable starches include potato, corn, wheat, tapioca, rice, waxy maize, barley, etc.
  • Cationic starches and cationic acrylamide-based polymers are preferred polymers according to the invention, and they can be used singly, together with each other or together with other polymers, particularly preferred are cationic starches and cationic acrylamide-based polymers having at least one aromatic group.
  • the cationic organic polymers can have one or more hydrophobic groups attached to them.
  • the hydrophobic groups can be aromatic groups, groups comprising aromatic groups or non-aromatic groups, preferably the hydrophobic groups comprise aromatic groups.
  • the hydrophobic group can be attached to a heteroatom, e.g. nitrogen or oxygen, the nitrogen optionally being charged, which heteroatom, in turn, it can be attached to the polymer backbone, for example via a chain of atoms.
  • the hydrophobic group may have at least 2 and usually at least 3 carbon atoms, suitably from 3 to 12 and preferably from 4 to 8 carbon atoms.
  • the hydrophobic group is suitably a hydrocarbon chain.
  • Suitable dosages counted as dry substance based on dry pulp and optional filler, of the cationic polymer in the system is from 0.01 to 50 kg/t (kg/tonne, "metric ton") of, preferably from 0.1 to 30 kg/t and most preferably from 1 to 15 kg/t.
  • Suitable dosages counted as dry substances based on dry pulp and optional filler, of the aqueous silica-containing composition defined above in the system are from 0.01 to 15 kg/t, preferably from 0.01 to 10 kg/t calculated as an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, and most preferably from 0.05 to 5 kg/t.
  • Suitable mineral fillers of conventional types may be added to the aqueous cellulosic suspension according to the invention.
  • suitable fillers include kaolin, china clay, titanium dioxide, gypsum, talc and natural and synthetic calcium carbonates such as chalk, ground marble and precipitated calcium carbonate (PCC).
  • Such aluminium compounds include alum, aluminates, aluminium chloride, aluminium nitrate, and polyaluminium compounds, such as polyaluminium chlorides, polyaluminium sulphates, polyaluminium compounds containing chloride and/or sulphate ions, polyaluminium silicate sulphates, and mixtures thereof.
  • the polyaluminium compounds may also contain other a ⁇ ions than chloride ions, for example anions from sulfuric acid, phosphoric acid, or organic acids such as citric acid and oxalic acid.
  • an aluminium compound in the present process it is usually preferably to add it to the stock prior to the polymer component and micro- or nano-particulate material.
  • Suitable addition levels of aluminium containing compounds is at least 0.001 kg/t, preferably from 0.01 to5 kg/t and more preferably from 0.05 to 1 kg/t, calculated as AI 2 O 3 based on dry pulp and optional filler.
  • anionic trash catchers examples include cationic polyamines, polymers or copolymers of quaternary amines, or aluminum containing compounds.
  • the process of this invention is used for the production of paper.
  • the term "paper”, as used herein, include not only paper and the production thereof, but also other web-like products, such as for example board and paperboard, and the production thereof.
  • the invention is particularly useful in the manufacture of paper having grammages below 150 g/nrr, preferably below 100 g/m , for example fine paper, newspaper, light weight coated paper, super calendered paper and tissue.
  • the process can be used in the production of paper from all types of stocks, both wood containing and woodfree.
  • the different types of suspensions of cellulose- containing fibres and the suspensions should suitably contain at least 25% by weight and preferably at least 50% of weight of such fibres, based on dry substance.
  • the suspensions comprise fibres from chemical pulp such as sulphate, sulphite and organosolv pulps wood-containing or mechanical pulp such as thermomechanical pulp, chemo-thermomechanical pulp, refiner pulp and groundwood pulp, from both hardwood and softwood, and can also be based on recycled fibres, optionally from de-inked pulps, and mixtures thereof.
  • the stock is a wood-containing stock, which have high contents of salts and therefore high conductivity.
  • the chemicals according to the present invention can be added to the aqueous cellulosic suspension, or stock, in conventional manner and in any order. It is usually preferably to add the cationic polymer to the stock before adding the aqueous silica-containing composition, even if the opposite order of addition may be used. It is further preferred to add the cationic polymer before a shear stage, which can be selected from pumping, mixing, cleaning, etc., and to add the aqueous silica-containing composition after that shear stage.
  • the aqueous silica-containing composition can be used as a flocculation agent in the treatment of water for the production of drinking water or as an environmental treatment of waters for instance in lakes.
  • the composition can also be used as flocculation agent in the treatment of waste water or waste sludges.
  • Parts and % relate to parts by weight and % by weight, respectively, and all solutions are aqueous, unless otherwise stated.
  • the units are metric.
  • Example 1 Test samples of the aqueous silica-containing compositions according to the invention were prepared by mixing an aqueous solution of naphthalene sulphonate formaldehyde condensate (NSF) with a silica sol containing silica-based particles in different dosages under moderate stirring. Reference samples were also prepared under the same condition as the test samples. One sample of NSF was ultra-filtrated and the obtained product (NSF I) had a concentration of 12% by weight and the samples were diluted to a concentration of 5% by weight and had a conductivity of 12 mS/cm. Another sample of NSF was ultra-filtrated and the obtained product (NSF I) had a concentration of 12% by weight and the samples were diluted to a concentration of 5% by weight and had a conductivity of 12 mS/cm. Another sample of NSF was ultra-filtrated and the obtained product (NSF I) had a concentration of 12% by weight and the samples were diluted to a concentration of 5% by
  • NSF was dialysed and the obtained product (NSF II) had a concentration of 12% by weight and the samples were diluted to a concentration of 5% by weight and had a conductivity of 12 mS/cm.
  • the silicas used in the following Examples are all defined below in Table 1.
  • SiO 2 :Na 2 O of 10 specific surface area of 870 m 2 /g, S-value of 35% and silica content of 10.0% by weight.
  • SiO 2 :Na 2 O of 45 specific surface area of 850 m 2 /g, aluminium modified with sodium aluminate to a degree of 0.25% AI 2 O 3 , and S-value of 20% and silica content of 8.0% by weight.
  • SiO 2 /Na 2 O of 17 obtained by mixing water glass having a molar ratio SiO 2 :Na 2 O of 3.4, a silica content of 15% by weight with polysilicic acid
  • test samples of naphthalene sulphonate formaldehyde condensate and silica-based particles in different dosages were added to a test stock to evaluate the performance of the composition as a drainage agent.
  • the drainage performance was evaluated by means of a Dynamic Drainage Analyser (DDA), available from Akribi, Sweden.
  • DDA Dynamic Drainage Analyser
  • the DDA measures the time for draining a set volume of stock through a wire when removing a plug and applying vacuum to that side of the wire opposite to the side on which the stock is present.
  • a cationic polymer was added to the stock before the aqueous silica-containing compositions according to the invention or the anionic reference.
  • the stock was stirred in a baffled jar at a speed of 1500 rpm throughout the test.
  • cationic starch (C1) which is a cationic potato starch with a nitrogen content of 0.5%, obtained by quarternisation of native potato starch with 3-chloro-2-hydroxypropyl dimethyl benzyl ammonium chloride was added to the stock, after 30 seconds of stirring the anionic mixture was added followed by 15 seconds stirring before drainage.
  • silica I was used as reference silica I. All the samples were diluted to 0.5% of solids before the tests. Ratios and results are summarised in Table 2.
  • Example 3 Test samples were prepared from NSF II and silica II. As reference silica II was used. All the samples were diluted to 0.5% solids before the drainage evaluation, which was performed as in Example 2, with the same stock and with 20 kg/t of C1. Ratios and results are summarised in Table 3.
  • Test samples were prepared from NSF I and Silica I. Silica I was used as a reference. The preparation procedure was the same as in previous examples. The conductivity of the wood containing stock was only 0.5 mS/cm. The amount of C1 was 30 kg/t in all tests. The drainage time for cationic starch added alone was 22 seconds. The ratios and dewatering times are summarised in Table 5.
  • test samples were prepared from NSF I and Silica I. As reference Silica I was used.
  • To the stock was 3 kg/t of a cationic polyacrylamide
  • C-PAM which was prepared by polymerisation of acrylamide (90 mol%) and acryloxy- ethyl-dimethyl-benzyl ammonium chloride (10 mol%), and having a molecular weight about 6,000,000, added in the beginning of the test. After 30 seconds of stirring a compositions of NSF I and Silica I were added followed by 15 seconds of stirring before drainage. The NSF i and Silica I compositions were diluted to 0.5% solids and the C-PAM to 0.1% solids prior to addition to the stock. The ratios and dewatering times are summarised in Table 6.
  • Test samples of compositions of NSF III and Silica I, and of NSF III and Silica III were prepared. A Drainage evaluation of the samples was performed as in previous
  • Test samples of compositions of NSF I and Silica I, and of NSF HI and Siiica 111 were prepared. As reference Silica I and Silica III were used. A drainage evaluation of the samples was performed as in previous Examples in a high conductivity stock with conductivity 5.0 mS/cm. C1 was added in an amount of 20 kg/t to the stock. The dewatering times summarised in Table 8.
  • a high molecular weight anionic polyacrylamide (A-PAM), MW from about 10 to 20 millions, containing about 30 mole-% anionic groups, in form of a water-in-oil emulsion inverted and diluted with water to a concentration of 0.1 %.
  • the A-PAM was mixed with 0.1% of Silica I in three different ratios of A-PAM to Silica I of 2:1, 1:1 and 0.5:1.
  • polysilicic acid with a concentration of 6.0 % SiO 2 a pH of 2.5, added under agitation for 20 minutes.
  • the polysilicic acid was prepared from diluted waterglass that was run through a column filed with hydrogen saturated, strongly cationic, ion exchange resin.
  • NSF Ill/Silica III (b) mixture was prepared mixing NSF III with polysilicic acid under agitation for 5 minutes and then this mixture was added to waterglass under agitation for 20 minutes.
  • a drainage evaluation of the samples of this example were performed on a high conductivity stock (5.0 m S/cm).
  • a cationic starch (C2) which was a cationic potato starch with a nitrogen content of 0.7%, obtained by quarternisation of native potato starch with 3-chloro-2-hydroxypropyl dimethyl benzyl ammonium chloride, was added before the anionic mixiures ⁇ u me /->» ⁇ . w..a_s_ _ au- ⁇ u « ⁇ C . eu i SIU in an amoun 4t. ⁇ ot* H 1O2Ik. g/t. The following dewatering times were obtained:
  • Example 11 Test samples of mixtures of NSF III / Silica I and of mixtures of NSF III / Silica III were prepared. As reference Silica III was used. A DDA evaluation of the samples was performed in a high conductivity stock with conductivity 5.0 mS/cm. C1 was added in an amount of 20 kg/t to the stock. The dewatering times summarised in Table 11.

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Abstract

The present invention refers to a process for the production of paper from a suspension containing cellulosic fibres, and optionally fillers, comprising adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles within the range of from 0.2:1 to 99:1, and containing naphthalene sulphonate formaldehyde condensate and silica-based particles in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent. The invention also encompasses an aqueous silica-containing composition and a method for preparation of an aqueous silica-containing composition.

Description

Aqueous silica-containing composition and process for production of paper
The present invention relates to a process for the production of paper from a suspension containing cellulosic fibres, comprising adding at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles. The invention further relates to an aqueous silica-containing composition and methods for the preparation of the aqueous silica-containing composition, and uses of the aqueous silica- containing composition.
Background of the Invention
In the papermaking art, an aqueous suspension containing cellulosic fibres, and optionally fillers and additives, referred to as stock, is fed into a headbox which ejects the stock onto a forming wire. Water is drained from the stock through the forming wire, so that a wet web of paper is formed and dewatered on the ire. The paper web is then dried in the drying section of the paper machine. Drainage and retention aids are conventionally introduced into the stock in order to facilitate drainage and to increase adsorption of fine particles onto the cellulosic fibres to retain them with the fibres on the wire.
US 4,388,150 discloses a binder in papermaking comprising a complex of cationic starch and colloidal silicic acid to produce a paper having increased strength and improved levels of retention of added minerals and papermaking fines.
US 4,750,974 discloses a coarcervate binder for use in papermaking comprising a tertiary combination of a cationic starch, an anionic high molecular weight polymer and a dispersed silica. US 5,368,833 discloses silica sols containing aluminium modified silica particles with high specific surface area and a high content of microgel.
US 6,083,997 discloses anionic nano-composites, which are prepared by adding a polyelectrolyte to silicate solution and then combining them with silicic acid. The nano- composites exhibit retention and drainage performance in papermaking. EP 0 418 015 A1 discloses an active sizing composition containing an aqueous emulsion in combination with an anionic dispersant or emulsifier. By using anionic polyacrylamide, anionic starch or colloidal silica the anionic charge density in the sizing composition can be extended.
US 4,443,496 refers to a method for modifying a surface layer of handened cement or substrates with use of the agent which comprises in a specified ratio of an alkali silicate solution and a sodium naphthalene sulphonate formaldehyde condensate. US 4,559,241 relates to an aqueous solution of alkali metal silicate and nitrite. The solution may also contain additives such as formaldehyde condensate with naphthalene sulphonate.
US 5,595,629 refers to a papermaking process comprising adding to the slurry an anionic polymer and cationic polymer in order to increase retention and/or dewatering. The anionic polymer comprises a formaldehyde condensate of naphthalene sulfonic acid salt with a molecular weight range of 500 to 120,000.
US 6,033,524 discloses a method for increasing retention and drainage of filling components in a paper making furnish in a paper making process comprising adding to the furnish a slurry of filling components, also containing a phenolic enhancer. US 4,772,332 pertains to a heat stabilised slurry of bulked kaolin pigment which is prepared by mixing a water soluble cationic material with kaolin clay pigment in the presence of water.
US 5,733,414 relates to a process for manufacturing paper from a cellulosic suspension comprising adding a water soluble cationic polymer and a water soluble formaldehyde condensate resin.
US 5,1 0414 discloses a procedure for manufacturing lignocellulosic material products and improving their strength and water resistant characteristics, high molar mass lignin derivatives being added to the material.
It would be advantageous to be able to provide drainage and retention aids with improved performance. It would also be advantageous to be able to provide retention and drainage aids with good storage stability. It would further be advantageous to be able to provide a papermaking process with improved drainage and/or retention performance.
The Invention According to the present invention it has unexpectedly been found that an improved drainage and/or retention effect of a cellulosic suspension on a wire can be obtained by using an aqueous silica-containing composition comprising anionic naphthalene sulphonate formaldehyde condensate and silica-based particles. The present invention makes it possible to increase the speed of the paper machine and to use a lower dosage of additives to give a corresponding drainage and/or retention effect, thereby leading to an improved papermaking process and economic benefits.
The terms "drainage and retention aid", as used herein, refer to one or more components, which when added to an aqueous cellulosic suspension, give better drainage and/or retention than obtained when not adding the said one or more components. AH types of stocks, in particular stocks having high contents of salts (high conductivity) and colloidal substances will obtain better drainage and retention performances by the addition of the composition according to the present invention. Improved drainage and retention performances are important in papermaking processes for instance in processes with a high degree of white water closure, i.e. extensive white water recycling and limited fresh water supply.
In accordance with the present invention there is provided a process for the production of paper from a suspension containing cellulosic fibres, and optionally fillers, comprising adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculated as SiO2,within the range of from 0.2:1 to 99:1 , and containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent. There is further provided an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles comprising aggregated or microgel formed silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculated as SiO2ι within the range of from 0.2:1 to 99:1, and containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2,in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent.
There is further provided an aqueous silica-containing composition obtainable by mixing anionic naphthalene sulphonate formaldehyde condensate with an aqueous alkali stabilised silica-based sol having an S-value in the range of from about 5 up to about 50% containing anionic aggregated or microgel formed silica-based particles, to provide an aqueous silica-containing composition containing an anionic naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica-containing composition, with the proviso that the aqueous silica-containing composition contains substantially no cellulose-reactive sizing agent.
There is further provided a method for preparation of an aqueous silica- containing composition, which comprises mixing in the presence of substantially no cellulose-reactive sizing agent an anionic naphthalene sulphonate formaldehyde condensate with an aqueous alkali stabilised silica-based sol having an S-value in the range of from about 5 up to about 50% containing anionic aggregated or microgel formed silica-based particles to provide an aqueous silica-containing composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles within the range of from 0.2:1 to 99:1 , and containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight.
There is further provided a method for preparation of an aqueous silica- containing composition, which comprises mixing an aqueous anionic naphthalene sulphonate formaldehyde condensate solution having a conductivity less than 20 mS/cm with an aqueous alkali stabilised sol containing silica-based particles to provide an aqueous silica-containing composition containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight.
There is further provided a method for preparation of an aqueous silica- containing composition, which comprises desalinating of an aqueous anionic naphthalene sulphonate formaldehyde condensate solution, mixing the desalinated aqueous anionic naphthalene sulphonate formaldehyde condensate solution with an aqueous alkali stabilised sol containing silica-based particles to provide an aqueous silica-containing composition containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight.
There is further provided a method for preparation of an aqueous silica- containing composition, which comprises mixing in the presence of substantially no cellulose-reactive sizing agent an anionic naphthalene sulphonate formaldehyde condensate with an aqueous alkali stabilised silica-based sol having an S-value in the range of from about 5 up to about 50% containing anionic aggregated or microgel formed silica-based particles, to provide an aqueous silica-containing composition containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight
There is further provided an aqueous silica-containing composition obtainable by the methods according to the invention.
The invention further relates to the use of the aqueous silica-containing composition of the invention, as flocculating agent in the production of pulp and paper and for water purification.
The process for the production of paper according to the present invention comprises adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising anionic naphthalene sulfonate formaldehyde condensate and silica-based particles. The term "anionic naphthalene sulfonate formaldehyde condensate" as used herein, represent a group of polymers obtained by condensation polymerisation of formaldehyde with one or more naphthalene sulphonic acids or salts thereof.
The naphthalene sulfonate formaldehyde condensate may be reacted with a base, such as alkali metal and alkaline earth hydroxides, e.g. sodium hydroxide, ammonia or an amine, e.g. triethylamine, thereby forming an alkali metal, alkaline earth or ammonium counter-ion.
The anionic naphthalene sulfonate formaldehyde condensate has a molecular weight of at least about 500, suitably from about 1,000. The upper limit is not critical it can be up to 1,000,000, usually up to 300,000, suitably up to 150,000 and preferably up to 60,000.
The aqueous silica-containing composition used in the process according to the invention also comprises anionic silica-based particles i.e. particles based on SiO2, preferably formed by polymerising silicic acid, encompassing both hornopolyiners and copolymers. Optionally the silica-based particles can be modified and contain other elements, e.g. amine, aluminium and/or boron, which can be present in the aqueous phase and/or in the silica-based particles.
Examples of suitable silica-based particles include colloidal silica, colloidal aluminium-modified silica or aluminium silicate, and different types of polysilicic acid and mixtures thereof, either alone or in combination with other types of anionic silica-based particles. In the art, polysilicic acid is also referred to as polymeric silicic acid, polysilicic acid microgel, polysilicate and polysilicate microgel, which are all encompassed by the term polysilicic acid used herein. Aluminium-containing compounds of this type are commonly referred to as polyaluminosilicate and polyaluminosilicate microgel including colloidal alumi- nium-modified silica and aluminium silicate.
It is preferred that the anionic silica-based particles are in the colloidal range of particle size, i.e. colloidal silica-based particles. This colloidal state comprises particles sufficiently small not to be affected by gravitational forces but sufficiently large not to show marked deviation from the properties of typical solutions, i.e. average particle size significantly less than 1 μm. The anionic silica-based particles have an average particle size suitably below about 50 nm, preferably below about 20 nm and more preferably in the range of from about 1 to about 50 nm, most preferably from about 1 nm up to about 10 nm. As conventional in silica chemistry, the particle size refers to the average size of the primary particles, which may be aggregated or non-aggregated. Suitably, the silica-based particles present in the aqueous silica-containing composition of the invention comprise aggregated or microgel formed silica-based particles, optionally and usually in combination with non-aggregated, or monodisperse, silica-based particles. Suitably the silica-based particles have a specific surface area larger than 50 m2/g, preferably larger than 100 m2/g. The specific surface area can be up to 1700 m2/g, preferably up to 1300 m2/g, and usually within the range from 300 to 1300 m2/g, preferably from 500 to 1050 m2/g. The specific surface area can be measured by means of titration with NaOH according to the method described by Sears, Analytical Chemistry 28(1956), 12, 1981-1983 or in U.S. Patent No. 5,176,891. The given area thus represents the average specific surface area of the particles.
The aqueous silica-containing composition used in the process according to the invention may have a weight ratio of anionic naphthalene sulphonate formaldehyde condensate to anionic silica-based particles, calculated asSiO2 , within the range of from 0.2:1 to 99:1 , suitably from 0.2:1 to 90:1 , preferably from 0.25:1 to 85:1. The total weight of the anionic naphthalene sulphonate formaldehyde condensate and anionic silica- based particles, calculated as SiO2, contained in the aqueous silica-containing uuiπμubiiiυn is Si itsaSi u.u i vo uy wtsiym, Caiuuiaicu un u ic ULSI wciyπi υi u ic ^jucυuS silica-containing composition, suitably the concentration of anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, calculated as SiO2| is within the range of 1 to 45% by weight, preferably within the range of 2 to 35 % by weight, most preferably 5 to 30% by weight.
The aqueous silica-containing composition can have an anionic charge density of at least 0.1 meq/g, usually the charge is within the range of 0.1 to 6 meq/g, suitably within the range of 0.1 to 5 meq/g, preferably within the range of 0.2 to 4 meq/g, and most preferably of 0.2 to 3.5 meq/g.
The aqueous silica-containing composition according to the invention contains substantially no cellulose-reactive sizing agent. By substantially no means that less or equal to 10% by weight, suitably less than 5%, preferably less than 1% by weight of cellulose-reactive sizing agent is present in the aqueous silica-containing composition. Most preferably there is no cellulose-reactive sizing agent in the aqueous silica- containing composition.
According to a preferred embodiment of the present invention, the aqueous silica-containing composition contains substantially no nitrites. By substantially no means that less or equal to 10% by weight, suitably less than 5%, preferably less than 1% by weight of nitrites is present in the aqueous silica-containing composition. Most preferably there is no cellulose-reactive sizing agent in the aqueous silica-containing composition, i.e. the composition is free from nitrites. The term "nitrites" encompass all nitrites such as nitrites of ammonium, lithium, kalium, sodium, calcium, and magnesium.
The present invention relates further to a method for preparation an aqueous silica-containing composition. The two components are preferably stirred together. The anionic naphthalene sulfonate formaldehyde condensate can be added to an aqueous sol containing the silica-based particles or the silica-based particles can be added to an aqueous solution of naphthalene sulfonate formaldehyde condensate. Prior to mixing the anionic naphthalene sulfonate formaldehyde condensate with the silica-based particles, the aqueous solution of anionic naphthalene sulfonate formaldehyde condensate may be desalinated or deionisated. The desalination or deionisation can be carried out with dialysis, membrane filtration, ultra-filtration, reversed osmosis or ion exchange or the like. It is preferred that the desalination or deionisation is carried out by the use of ultra-filtration or dialysis. The anionic naphthalene sulfonate formaldehyde condensate to be mixed with the silica-based particles has the previously mentioned properties and has a conductivity less than 30 mS/cm, suitable less than 25 mS/cm, preferably less than 20 mS/cm, and most preferably less than 15 mS/cm measured at an anionic naphthalene sulfonate formaldehyde condensate content of 10%. The conductivity is usually at least 1 mS/cm, suitably at least 3 mS/cm and preferably within the range of from 5 to 15 mS/cm, measured at an anionic naphthalene sulfonate formaldehyde condensate content of 10%.
The silica-based particles, preferably anionic, to be mixed with anionic naphthalene sulfonate formaldehyde condensate have the previously mentioned properties. Suitably the silica-based particles are contained in a sol, preferably alkali stabilised, before mixing with anionic naphthalene sulfonate formaldehyde condensate. The sol may have an S-value in the range of from 5 to 50%, preferably from 8 to 45%, and most preferably from 10 to 30%. Calculation and measuring of the S-value can be performed as described by Her & Dalton in J. Phys. Chem. 60(1956), 955-957. The S-value indicates the degree of aggregate or microgel formation and a lower S-value is indicative of a higher degree of aggregation. Suitably, the silica-based particles comprise aggregated or microgel formed silica-based particles, optionally and usually in combination with non- aggregated, or monodisperse, silica-based particles.
Suitably the silica-based particles have a molar ratio Si2O:Na2O less than 60, usually within the range 5 to 60, and preferably within the range from 8 to 55.
The anionic naphthalene sulphonate formaldehyde condensate is usually mixed with silica-based particles in a weight ratio within a range of from 0.2:1 to 99:1 , suitably from 0.2:1 to 90:1 , preferably from 0.25:1 to 85:1.
The products prepared by any of these methods exhibits an improved storage stability and therefore a better drainage and retention aid performance when stored.
The mixing procedure of above mention methods is suitably carried out in the presence of substantially no cellulose-reactive sizing agent. By substantially no means that less or equal to 10% by weight, suitably less than 5%, preferably less than 1% by weight of cellulose-reactive sizing agent is present. Most preferably there is no cellulose- reactive sizing agent present.
The present invention further relates to a process for the production of paper from an aqueous suspension containing cellulosic fibres. The process comprises adding to the suspension a cationic organic polymer and the aqueous silica-containing composition of the invention. The cationic organic polymer according to the invention can be linear, branched or cross-linked. Preferably the cationic polymer is water-soluble or water-dispersible. Examples of suitable cationic polymers include synthetic organic polymers, e.g. step-growth polymers and chain-growth polymers, and polymers derived from natural sources, e.g. polysaccharides.
Examples of suitable cationic synthetic organic polymers include vinyl addition polymers such as acrylate- and acrylarnide-based polymers, as well as cationic poly(diallyl dimethyl ammonium chloride), cationic polyethylene imines, cationic polyamines, polyamidoamines and vinylamide-based polymers, melamine-formaldehyde and urea-formaldehyde resins.
Examples of suitable polysaccharides include starches, guar gums, celluloses, chitins, chitosans, glycans, galactans, glucans, xanthan gums, pectins, mannans, dextrins, preferably starches and guar gums. Examples of suitable starches include potato, corn, wheat, tapioca, rice, waxy maize, barley, etc.
Cationic starches and cationic acrylamide-based polymers are preferred polymers according to the invention, and they can be used singly, together with each other or together with other polymers, particularly preferred are cationic starches and cationic acrylamide-based polymers having at least one aromatic group.
The cationic organic polymers can have one or more hydrophobic groups attached to them. The hydrophobic groups can be aromatic groups, groups comprising aromatic groups or non-aromatic groups, preferably the hydrophobic groups comprise aromatic groups. The hydrophobic group can be attached to a heteroatom, e.g. nitrogen or oxygen, the nitrogen optionally being charged, which heteroatom, in turn, it can be attached to the polymer backbone, for example via a chain of atoms. The hydrophobic group may have at least 2 and usually at least 3 carbon atoms, suitably from 3 to 12 and preferably from 4 to 8 carbon atoms. The hydrophobic group is suitably a hydrocarbon chain.
Suitable dosages counted as dry substance based on dry pulp and optional filler, of the cationic polymer in the system is from 0.01 to 50 kg/t (kg/tonne, "metric ton") of, preferably from 0.1 to 30 kg/t and most preferably from 1 to 15 kg/t.
Suitable dosages counted as dry substances based on dry pulp and optional filler, of the aqueous silica-containing composition defined above in the system are from 0.01 to 15 kg/t, preferably from 0.01 to 10 kg/t calculated as an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, and most preferably from 0.05 to 5 kg/t.
Suitable mineral fillers of conventional types may be added to the aqueous cellulosic suspension according to the invention. Examples of suitable fillers include kaolin, china clay, titanium dioxide, gypsum, talc and natural and synthetic calcium carbonates such as chalk, ground marble and precipitated calcium carbonate (PCC).
Further additives that are conventional in papermaking can of course be used in combination with the chemicals according to the invention, for example anionic trash catchers (ATC), wet strength agents, dry strength agents, optical brightening agents, dyes, aluminium compounds, etc. Examples of suitable aluminium compounds include alum, aluminates, aluminium chloride, aluminium nitrate, and polyaluminium compounds, such as polyaluminium chlorides, polyaluminium sulphates, polyaluminium compounds containing chloride and/or sulphate ions, polyaluminium silicate sulphates, and mixtures thereof. The polyaluminium compounds may also contain other aπions than chloride ions, for example anions from sulfuric acid, phosphoric acid, or organic acids such as citric acid and oxalic acid. When employing an aluminium compound in the present process, it is usually preferably to add it to the stock prior to the polymer component and micro- or nano-particulate material. Suitable addition levels of aluminium containing compounds is at least 0.001 kg/t, preferably from 0.01 to5 kg/t and more preferably from 0.05 to 1 kg/t, calculated as AI2O3 based on dry pulp and optional filler.
Examples of suitable anionic trash catchers include cationic polyamines, polymers or copolymers of quaternary amines, or aluminum containing compounds.
The process of this invention is used for the production of paper. The term "paper", as used herein, include not only paper and the production thereof, but also other web-like products, such as for example board and paperboard, and the production thereof. The invention is particularly useful in the manufacture of paper having grammages below 150 g/nrr, preferably below 100 g/m , for example fine paper, newspaper, light weight coated paper, super calendered paper and tissue. The process can be used in the production of paper from all types of stocks, both wood containing and woodfree. The different types of suspensions of cellulose- containing fibres and the suspensions should suitably contain at least 25% by weight and preferably at least 50% of weight of such fibres, based on dry substance. The suspensions comprise fibres from chemical pulp such as sulphate, sulphite and organosolv pulps wood-containing or mechanical pulp such as thermomechanical pulp, chemo-thermomechanical pulp, refiner pulp and groundwood pulp, from both hardwood and softwood, and can also be based on recycled fibres, optionally from de-inked pulps, and mixtures thereof. Preferably the stock is a wood-containing stock, which have high contents of salts and therefore high conductivity. The chemicals according to the present invention can be added to the aqueous cellulosic suspension, or stock, in conventional manner and in any order. It is usually preferably to add the cationic polymer to the stock before adding the aqueous silica-containing composition, even if the opposite order of addition may be used. It is further preferred to add the cationic polymer before a shear stage, which can be selected from pumping, mixing, cleaning, etc., and to add the aqueous silica-containing composition after that shear stage.
The aqueous silica-containing composition can be used as a flocculation agent in the treatment of water for the production of drinking water or as an environmental treatment of waters for instance in lakes. The composition can also be used as flocculation agent in the treatment of waste water or waste sludges.
The invention is further illustrated in the following examples, which are not intended to limit the scope thereof. Parts and % relate to parts by weight and % by weight, respectively, and all solutions are aqueous, unless otherwise stated. The units are metric.
Example 1 Test samples of the aqueous silica-containing compositions according to the invention were prepared by mixing an aqueous solution of naphthalene sulphonate formaldehyde condensate (NSF) with a silica sol containing silica-based particles in different dosages under moderate stirring. Reference samples were also prepared under the same condition as the test samples. One sample of NSF was ultra-filtrated and the obtained product (NSF I) had a concentration of 12% by weight and the samples were diluted to a concentration of 5% by weight and had a conductivity of 12 mS/cm. Another sample of
NSF was dialysed and the obtained product (NSF II) had a concentration of 12% by weight and the samples were diluted to a concentration of 5% by weight and had a conductivity of 12 mS/cm. Untreated samples of NSF (NSF III) were diluted to a concentration of 5% by weight and had a conductivity of 25 mS/cm. All conductivities in the Examples were measured at a concentration of 10% by weight of NSF. The silicas used in the following Examples are all defined below in Table 1.
Table 1
Silica I Silica sol of the type described in US 5,447,604 having a molar ratio
SiO2:Na2O of 10, specific surface area of 870 m2/g, S-value of 35% and silica content of 10.0% by weight.
Silica II Silica sol of the type described in US 5,603,805 having a molar ratio
SiO2:Na2O of 45, specific surface area of 850 m2/g, aluminium modified with sodium aluminate to a degree of 0.25% AI2O3, and S-value of 20% and silica content of 8.0% by weight.
Silica III Silica sol of the type described in US 6,083,997 having a molar ratio
SiO2/Na2O of 17 obtained by mixing water glass having a molar ratio SiO2:Na2O of 3.4, a silica content of 15% by weight with polysilicic acid
(PSA), having a silica content of 6.0% by weight.
Example 2
In the following examples test samples of naphthalene sulphonate formaldehyde condensate and silica-based particles in different dosages were added to a test stock to evaluate the performance of the composition as a drainage agent. The drainage performance was evaluated by means of a Dynamic Drainage Analyser (DDA), available from Akribi, Sweden. The DDA measures the time for draining a set volume of stock through a wire when removing a plug and applying vacuum to that side of the wire opposite to the side on which the stock is present.
In the examples a cationic polymer was added to the stock before the aqueous silica-containing compositions according to the invention or the anionic reference.
Test samples prepared from mixtures of NSF II and Silica I in different ratios, which were tested on a test stock, which was a wood containing stock naviπg a pH of 7.6, a conductivity of 5.0 mS/cm, and a consistency of 1.43 g/l. The stock was stirred in a baffled jar at a speed of 1500 rpm throughout the test. In the tests 20 kg/t (20 kg/tonne) of cationic starch (C1), which is a cationic potato starch with a nitrogen content of 0.5%, obtained by quarternisation of native potato starch with 3-chloro-2-hydroxypropyl dimethyl benzyl ammonium chloride was added to the stock, after 30 seconds of stirring the anionic mixture was added followed by 15 seconds stirring before drainage. As reference silica I was used. All the samples were diluted to 0.5% of solids before the tests. Ratios and results are summarised in Table 2.
Table 2
Example 3 Test samples were prepared from NSF II and silica II. As reference silica II was used. All the samples were diluted to 0.5% solids before the drainage evaluation, which was performed as in Example 2, with the same stock and with 20 kg/t of C1. Ratios and results are summarised in Table 3.
Table 3
Example 4 Test samples were prepared from NSF I and Silica I. Silica I was used as reference. The samples were diluted to 0.5% solids and drainage tests were performed as in Example 1. To the test stock was added 20 kg/t of C1. The stock was a wood containing stock having a conductivity of 5.0 mS/cm, a consistency of 1.52 g/l and pH = 7.8. The ratios and dewatering times are summarised in Table 4.
Table 4
Example 5
Test samples were prepared from NSF I and Silica I. Silica I was used as a reference. The preparation procedure was the same as in previous examples. The conductivity of the wood containing stock was only 0.5 mS/cm. The amount of C1 was 30 kg/t in all tests. The drainage time for cationic starch added alone was 22 seconds. The ratios and dewatering times are summarised in Table 5.
Table 5
Example 6
The test samples were prepared from NSF I and Silica I. As reference Silica I was used. The stock was wood containing having a conductivity of 5.0 mS/cm, a consistency of 1.52 g/l and pH = 7.8. To the stock was 3 kg/t of a cationic polyacrylamide
(C-PAM), which was prepared by polymerisation of acrylamide (90 mol%) and acryloxy- ethyl-dimethyl-benzyl ammonium chloride (10 mol%), and having a molecular weight about 6,000,000, added in the beginning of the test. After 30 seconds of stirring a compositions of NSF I and Silica I were added followed by 15 seconds of stirring before drainage. The NSF i and Silica I compositions were diluted to 0.5% solids and the C-PAM to 0.1% solids prior to addition to the stock. The ratios and dewatering times are summarised in Table 6.
Table 6
Example 7
Test samples of compositions of NSF III and Silica I, and of NSF III and Silica III were prepared. A Drainage evaluation of the samples was performed as in previous
Examples in a high conductivity stock with conductivity 5.0 mS/cm. C1 was added in an amount of 20 kg/t to the stock. The ratios and dewatering times are summarised in Table 7.
Table 7
The results show that the aqueous silica-containing composition according to the invention have improved drainage properties.
Example 8
Test samples of compositions of NSF I and Silica I, and of NSF HI and Siiica 111 were prepared. As reference Silica I and Silica III were used. A drainage evaluation of the samples was performed as in previous Examples in a high conductivity stock with conductivity 5.0 mS/cm. C1 was added in an amount of 20 kg/t to the stock. The dewatering times summarised in Table 8.
Table 8
The results show that the aqueous silica-containing compositions according to the invention have improved drainage properties.
Example 9
A high molecular weight anionic polyacrylamide (A-PAM), MW from about 10 to 20 millions, containing about 30 mole-% anionic groups, in form of a water-in-oil emulsion inverted and diluted with water to a concentration of 0.1 %. The A-PAM was mixed with 0.1% of Silica I in three different ratios of A-PAM to Silica I of 2:1, 1:1 and 0.5:1. Compositions of NSF III and Silica III (a) was prepared by adding a diluted water glass (15% SiO2 and ratio SiO2/Na2O = 3.4) to NSF III (as 30% water solution) under agitation. To this mixture was polysilicic acid, with a concentration of 6.0 % SiO2 a pH of 2.5, added under agitation for 20 minutes. The polysilicic acid was prepared from diluted waterglass that was run through a column filed with hydrogen saturated, strongly cationic, ion exchange resin.
NSF Ill/Silica III (b) mixture was prepared mixing NSF III with polysilicic acid under agitation for 5 minutes and then this mixture was added to waterglass under agitation for 20 minutes.
A drainage evaluation of the samples of this example were performed on a high conductivity stock (5.0 m S/cm). A cationic starch (C2), which was a cationic potato starch with a nitrogen content of 0.7%, obtained by quarternisation of native potato starch with 3-chloro-2-hydroxypropyl dimethyl benzyl ammonium chloride, was added before the anionic mixiures ιu me /->»} . w..a_s_ _ au-ιu«ι C . eu i SIU in an amoun 4t. ~ ot* H 1O2Ik. g/t. The following dewatering times were obtained:
Table 9
Example 10
The storage stability of different mixtures of NSF and silica were determined. Samples of NSF was desalinated by the use of ultrafiltration (NSF I) to a conductivity of 12 mS/cm measured at 10% by weight of solids before mixing with silica to form aqueous compositions. Untreated NSF III were mixed with silica for comparison. All obtained aqueous compositions and the reference samples were stored according to the following procedure:
In a refrigerator for 9 weeks; then in oven at a temperature of 40°C for 3 weeks; in oven at a temperature of 60°C for 1 week; and in oven at a temperature of 80°C for 6 weeks. The total storage time was 20 weeks. The storage times for the test samples are summarised in Table 10.
Table 10
The samples with no gel formation show better stability than the samples with gel- formation, and they did not even show an increase in viscosity.
Example 11 Test samples of mixtures of NSF III / Silica I and of mixtures of NSF III / Silica III were prepared. As reference Silica III was used. A DDA evaluation of the samples was performed in a high conductivity stock with conductivity 5.0 mS/cm. C1 was added in an amount of 20 kg/t to the stock. The dewatering times summarised in Table 11.
Table 11
The results show that the mixtures containing Silica I have received improved dewatering times compared to Silica III. Silica I is an alkali stabilised silica sol.

Claims

Claims
1. A process for the production of paper from a suspension containing cellulosic fibres, and optionally fillers, comprising adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculates as SiO2,within the range of from 0.
2:1 to 99:1 , and containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2l in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent.
I i lσ μi uυcoo α vji uiπ IU iciii i i i , vvi ici σiu n iσ CII nui ιι > oiu α-uαoσu μαuiuco comprise aggregated or microgel formed silica-based particles.
3. The process according to claim 1 or 2, wherein the anionic naphthalene sulphonate formaldehyde condensate has a conductivity of less than 20 mS/cm.
4. The process according to claim 3, wherein the anionic naphthalene sulphonate formaldehyde condensate has a conductivity of less than 15 mS/cm.
5. The process according to any of the preceding claims, wherein the aqueous silica-containing composition has a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculated as SiO2, within the range of from 0.2:1 to 90:1.
6. The process according to any of the preceding claims, wherein the anionic silica- based particles have a specific surface area within the range of from 300 to 1300 m2/g.
7. The process according to any of the preceding claims, wherein the cationic organic polymer is cationic starch or cationic polyacrylamide.
8. The process according to any of the preceding claims, wherein the cationic organic polymer has at least one aromatic group.
9. Use of an aqueous silica-containing composition according to any of claims 1 to
8, as a flocculating agent in the production of pulp and paper and for water purification.
10. An aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles comprising aggregated or microgel formed silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculated as SiO2, within the range of from 0.2:1 to 99:1, and containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica- containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent.
11. An aqueous silica-containing composition obtainable by mixing anionic naphthalene sulphonate formaldehyde condensate with an aqueous alkali stabilised silica-based sol having an S-value in the range of from about 5 up to about 50% containing anionic aggregated or microgel formed silica-based particles , to provide an aqueous silica-containing composition containing an anionic naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight, based on the total weight of the aqueous silica-containing composition, with the proviso that the aqueous silica-containing composition contains substantially no cellulose-reactive sizing agent.
12. The aqueous silica-containing composition according to claim 10 or 11 , wherein the anionic naphthalene sulphonate formaldehyde condensate has a conductivity of less than 15 mS/cm.
13. The aqueous silica-containing composition according to claim 10 or 11, wherein the aqueous silica-containing composition has a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculated as SiO2, within the range of from 0.2:1 to 90:1.
14. The aqueous silica-containing composition according to claim 10 or 11 , wherein the silica-based particles have a specific surface area within the range of from 300 to 1300 m2/g.
15. A method for preparation of an aqueous silica-containing composition, which comprises mixing in the presence of substantially no cellulose^reactive sizing agent an anionic naphthalene sulphonate formaldehyde condensate with an aqueous alkali stabilised silica-based sol having an S-value in the range of from about 5 up to about 50% containing anionic aggregated or microgel formed silica-based particles to provide an aqueous silica-containing composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculated as SiO2, within the range of from 0.2:1 to 99:1 , and containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight.
16. A method for preparation of an aqueous silica-containing composition, which comprises mixing an aqueous anionic naphthalene sulphonate formaldehyde condensate solution having a conductivity less than 20 mS/cm with an aqueous alkali stabilised so! containing silica-based particles to provide an aqueous silica-containing composition containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight.
17. A method for preparation of an aqueous silica-containing composition, which comprises desalinating of an aqueous anionic naphthalene sulphonate formaldehyde condensate solution, mixing the desalinated aqueous anionic naphthalene sulphonate formaldehyde condensate solution with an aqueous alkali stabilised sol containing silica- based particles to provide an aqueous silica-containing composition containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight.
18. A method for preparation of an aqueous silica-containing composition, which comprises mixing in the presence of substantially no cellulose-reactive sizing agent an anionic naphthalene sulphonate formaldehyde condensate with an aqueous alkali stabilised silica-based sol having an S-value in the range of from about 5 up to about 50% containing anionic aggregated or microgel formed silica-based particles , to provide an aqueous silica-containing composition containing naphthalene sulphonate formaldehyde condensate and silica-based particles, calculated as SiO2, in an amount of at least 0.01 % by weight.
19. The method according to claims 15, 16, 17 or 18, wherein the anionic naphthalene sulphonate formaldehyde condensate has a conductivity of less than 15 mS/cm.
20. The method according to claims 15, 16, 17 or 18, wherein the aqueous silica- containing composition has a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles, calculated as SiO2, within the range of from 0.2:1 to 90:1.
21. The method according to claims 15, 16, 17 or 18, wherein the silica-based particles have a specific surface area within the range of from 300 to 1300 m2/g.
22. The method according to claims 16 or 17, wherein the sol has an S-value within the range of from 5 to 50% prior to mixing with the anionic of naphthalene sulphonate formaldehyde condensate.
23. The method according to claims 15, 16, 17 or 18, wherein the sol has an S-value within the range of from 8 to 45% prior to mixing with the anionic of naphthalene sulphonate formaldehyde condensate.
EP02793739.0A 2001-12-21 2002-12-20 Aqueous silica-containing composition and process for production of paper Expired - Lifetime EP1456469B1 (en)

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US7323083B2 (en) 2002-10-30 2008-01-29 The Lubrizol Corporation Adhesion promoters for glass-containing systems
EP1560858A1 (en) 2002-10-30 2005-08-10 The Lubrizol Corporation Adhesion promoters for glass-containing systems
US7955473B2 (en) 2004-12-22 2011-06-07 Akzo Nobel N.V. Process for the production of paper
JP4837032B2 (en) * 2005-05-16 2011-12-14 アクゾ ノーベル ナムローゼ フェンノートシャップ Paper manufacturing method
US20060254464A1 (en) 2005-05-16 2006-11-16 Akzo Nobel N.V. Process for the production of paper
AU2016282408C1 (en) * 2015-06-23 2020-07-02 Kemira Oyj Method for controlling hydrophobic particles in aqueous environment in paper or board manufacture
CN113984743B (en) * 2021-09-30 2022-08-16 华南理工大学 Formaldehyde detection test paper based on nano composite fiber and preparation method and application thereof
CN115504716B (en) * 2022-10-10 2023-04-07 湖北工业大学 Sterilization, antivirus and stain-resistant plastering mortar and preparation method thereof

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2549089C3 (en) * 1974-11-15 1978-12-14 Sandoz-Patent-Gmbh, 7850 Loerrach Process for improving the retention and drainage effect in paper manufacture
JPS5924759B2 (en) * 1981-07-30 1984-06-12 日産化学工業株式会社 Surface layer modifier for cement-based hardened products
JPS60108385A (en) * 1983-11-11 1985-06-13 日産化学工業株式会社 Degradation prevention for cementitious material
FI83348C (en) * 1987-03-09 1996-01-09 Metsae Serla Oy Process for making products from lignocellulosic material
US4772332A (en) * 1987-04-21 1988-09-20 Engelhard Corporation Use of mixture of high molecular weight sulfonates as auxiliary dispersant for structured kaolins
GB8920456D0 (en) * 1989-09-11 1989-10-25 Albright & Wilson Active sizing compositions
PH31656A (en) * 1994-02-04 1999-01-12 Allied Colloids Ltd Process for making paper.
GB2294708B (en) * 1994-11-04 1998-08-05 Ciba Geigy Ag Fluorescent whitening agent formulation
US5595629A (en) * 1995-09-22 1997-01-21 Nalco Chemical Company Papermaking process
US6165259A (en) * 1997-02-05 2000-12-26 Akzo Nobel N.V. Aqueous dispersions of hydrophobic material
US6033524A (en) * 1997-11-24 2000-03-07 Nalco Chemical Company Selective retention of filling components and improved control of sheet properties by enhancing additive pretreatment

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO03056100A1 *

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