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
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/04—Addition to the pulp; After-treatment of added substances in the pulp
  • D21H23/06—Controlling the addition
  • D21H23/08—Controlling the addition by measuring pulp properties, e.g. zeta potential, pH
• • 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
• • 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
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/14—Secondary fibres
• • 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
  • D21H17/01—Waste products, e.g. sludge
• • 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
• • 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
• • 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
  • D21H17/31—Gums
  • D21H17/32—Guar or other polygalactomannan gum
• • 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
  • D21H17/63—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
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/04—Addition to the pulp; After-treatment of added substances in the pulp
  • D21H23/06—Controlling the addition
  • D21H23/08—Controlling the addition by measuring pulp properties, e.g. zeta potential, pH
  • D21H23/10—Controlling the addition by measuring pulp properties, e.g. zeta potential, pH at least two kinds of compounds being added

Definitions

• This invention relates to papermaking and more specifically to a process for the production of paper in which a cationic or amphoteric polysaccharide containing hydrophobic substitution is added to a papermaking stock
• the process provides improved drainage and retention as well as improved dry strength of the paper produced by the process
• an aqueous suspension containing cellulosic fibres and optional fillers and additives referred to as stock
• 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 on the wire, and the web is further dewatered and dried in the drying section of the paper machine
• white water which usually contains fine particles, e g fine fibres, fillers and additives
• Drainage and retention aids are conventionally introduced into the stock in order to facilitate drainage and increase adsorption of fine particles onto the cellulosic fibres so that they are retained with the fibres on the wire
• Cationic and amphoteric polysaccha ⁇ des like cationic starch and cationic guar gums are widely used as drainage and retention aids
• the polysacc arides can be used alone or in combination with other polymers and/
• Cationic polysaccharides are usually prepared by the reaction of a polysaccharide with a quaternising agent, e g 3-chloro-2-hydroxypropyl t ⁇ methylammonium chloride 2,3-epoxypropyl trimethyl ammonium chloride, and 2-chloroethyl t ⁇ methyl ammonium chloride
• a quaternising agent e g 3-chloro-2-hydroxypropyl t ⁇ methylammonium chloride 2,3-epoxypropyl trimethyl ammonium chloride, and 2-chloroethyl t ⁇ methyl ammonium chloride
• U S Patent Nos 4,388,150, 4,755,259, 4,961 ,825, 5,127,994, 5,643,414, 5,447,604, 5,277,764, 5,607,552, 5,603,805, and 5,858,174, and European Patent No 500,770 disclose the use of cationic and amphoteric polysaccharides and anionic inorganic particles as stock additives in papermaking These additives are among the most efficient drainage and retention aids now in use
• the present invention relates to a process for the production of paper from a suspension containing cellulosic fibres, and optional fillers, which comprises adding to the suspension a drainage and retention aid comprising a cationic or amphoteric polysaccharide, forming and dewatering the suspension on a wire, wherein the polysaccharide has a hydrophobic group
• the invention further relates to a process for the production of paper from a suspension containing cellulosic fibres, and optional fillers, which comprises adding to the suspension a dry strength agent comprising a cationic or ampho
• the process of this invention results in improved drainage and/or retention and hereby the present process makes it possible to increase the speed of the paper machine and to use lower a dosage of additive to give a corresponding drainage and retention effect thereby leading to an improved papermaking process and economic benefits
• Further benefits observed with the present invention include improved dry strength of the paper produced using the polysaccharide having a hydrophobic group
• the process of this invention is suitably used for the treatment of cellulosic suspensions in closed mills wherein the white water is repeatedly recycled with the introduction of only low amounts of fresh water
• the process is further suitably applied to papermaking processes using cellulosic suspensions having high salt contents, and thus having high conductivity levels, for example processes with extensive white water recycling and limited fresh water supply and/or processes using fresh water having high salt contents
• the polysaccharide according to this invention can be selected from any polysaccharide known in the art including, for example, starches, guar gums, celluloses
• the polysaccharide is capable of functioning as a dry strength agent
• dry strength agent refers to at least one component (aid, agent or additive) which, when being added to a stock give better dry strength of the paper produced than is obtained when not adding the said component
• the polysaccharide is a hydrophobe substituted, cationic or amphoteric polysaccharide, i e a polysaccharide having one or more hydrophobic groups and one or more cationic groups, the cationic groups suitably being tertiary amino groups or preferably, quaternary ammonium groups
• the polysaccharide may also contain one or more anionic groups which can be, for example, phosphate, phosphonate, sulphate sulphonate or carboxy c acid groups and they are preferably phosphate groups If present the anionic groups can be native or introduced by means of chemical treatment in conventional manner, native potato starch contains a substantial amount of covalentiy bound phosphate monoester groups
• cationic groups are preferably present in a predominant amount
• the hydrophobic group of the polysaccharide can be attached to a heteroatom like oxygen present in the polysaccharide
• the hydrophobic group is attached to a heteroatom, e g nitrogen or oxygen, the heteroatom optionally being charged, for example when it is a nitrogen, or a group comprising such a heteroatom, e g , amide, ester or ether, which, in turn, can be attached to the polysaccharide backbone (main chain), for example via a chain of atoms
• the hydrophobic group has at least 2, usually at least 3, suitably at least 4 and preferably at least 6 carbon atoms, and usually up to about 20 suitably up to 14 and preferably up to 12 carbon atoms
• the hydrophobic group can be selected from aromatic (aryl) groups, aliphatic hydrocarbon groups, and mixtures of such groups Examples of suitable hydrophobic aliphatic groups include linear, branched and cyclic alkyl groups like ethyl, propyl, e g n
• Particularly suitable polysaccharides according to the invention include those comprising the general structural formula (I)
• P is a residue of a polysaccharide
• A is a group attaching N to the polysaccharide residue, suitably a chain of atoms comprising C and H atoms, and optionally O and/or N atoms, usually an alkylene group with from 2 to 18 and suitably 2 to 8 carbon atoms optionally interrupted or substituted by one or more heteroatoms, e g O or N e g an alkyleneoxy group or hydroxy propylene group (- CH 2 - CH(OH) - CH 2 - ),
• R 1 and R 2 are each H or, preferably, a hydrocarbon group, suitably alkyl, having from 1 to 3 carbon atoms, suitably 1 or 2 carbon atoms,
• R 3 is a hydrophobic hydrocarbon group containing at least 2 carbon atoms, suitably 4 to 14 and preferably 6 to 12 carbon atoms, the hydrophobic group suitably being as defined above,
• the hydrophobic group modified cationic or amphoteric polysaccharide can have a degree of substitution varying over a wide range
• the degree of cationic substitution (DS C ) can be from 0,01 to 0,5, suitably from 0,02 to 0,3, preferably from 0,025 to 0,2
• the degree of hydrophobic substitution (DS H ) can be from from 0,01 to 0,5, suitably from 0,02 to 0,3 preferably from 0,025 to 0,2
• the degree of anionic substitution (DS A ) can be from 0 to
• the polysaccharides according to the invention can be prepared by subjecting a polysaccharide to cationic and hydrophobic modification in known manner using one or more agents containing a cationic group and/or a hydrophobic group, for example by reacting the agent with the polysaccharide in the presence of an alkaline substance such as an alkali metal or alkaline earth metal hydroxide
• the polysaccharide to be subjected to cationic and hydrophobic modification can be non-ionic, anionic, amphoteric or cationic
• Suitable modifying agents include non-ionic agents such as, for example, hydrophobe substituted succinic anhydrides, alkylene oxides, e g propylene oxide and butylene oxide 5 alkyl halides, e g decyl bromide and docecyl bromide, aralkyl hahdes, e g benzyl chloride and benzyl bromide, the reaction products of epichlorohyd ⁇ n and dialkylamines having at least one substituent comprising a hydrophobic group as defined above, including 3-d ⁇ alkyl- am ⁇ no-1 ,2-epoxypropanes, and cationic agents such as, for example, the reaction product of epichlorohyd ⁇ n and tertiary amines having at least one substituent comprising a hydro- phobic group as defined above, including t ⁇ alkylamines, alkaryldialkylamines, e g dimethyl- benzylamine, arylamine
• Anionic inorganic particles that can be used according to the invention include anionic silica-based particles and clays of the smectite type It is preferred that the anionic inorganic particles are in the colloidal range of particle size
• Anionic silica-based particles, i e particles based on S ⁇ 0 2 or silicic acid, are preferably used and such particles are usually supplied in the form of aqueous colloidal dispersions, so-called sols
• suitable silica-based particles include colloidal silica and different types of polysi cic acid
• the silica- based sols can also be modified and contain other elements, e g aluminium and/or boron, which can be present in the aqueous phase and/or in the silica-based particles
• Suitable silica-based particles of this type include colloidal aluminium-modified silica and aluminium silicates Mixtures of such suitable silica-based particles can also be used Drainage and retention aids comprising suitable anionic silic
• Anionic silica-based particles suitably have an average particle size below about 50 nm, preferably below about 20 nm and more preferably in the range of from about 1 to about 10 nm
• the particle size refers to the average size of the primary particles, which may be aggregated or non-aggregated
• the specific surface area of the silica-based particles is suitably above 50 m 2 /g and preferably above 100 m 2 /g Generally, the specific surface area can be up to about 1700 m 2 /g and preferably up to 1000 m 2 /g
• the specific surface area can be measured by means of titration with NaOH in known manner, e g as described by Sears in Analytical Chemistry 28(1956) 12, 1981-1983 and in U S Patent No 5,176,891 The given area thus represents the average specific surface area of the particles
• the anionic inorganic particles are silica-based particles having a specific surface area within the range of from 50 to 1000 m 2 /g, preferably from 100 to 950 m 2 /g Sols of silica-based particles these types also encompass modified sols like aluminium-containing silica-based sols and boron-containing silica-based sols
• the silica-based particles are present in a sol having an S- value in the range of from 8 to 45%, preferably from 10 to 30%, containing silica-based 7 particles with a specific surface area in the range of from 300 to 1000 m 2 /g, suitably from
• the particles can be surface- modified with aluminium to a degree of from 2 to 25% substitution of silicon atoms
• the S- value can be measured and calculated 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 are selected from polysihcic acid and modified polysilicic acid having a high specific surface area, suitably above about 1000 m 2 /g
• the specific surface area can be within the range of from 1000 to 1700 m 2 /g and preferably from 1050 to 1600 m 2 /g
• the sols of modified polysilicic acid can contain other elements, e g aluminium and/or boron, which can be present in the aqueous phase and/or in the 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 also referred to as poly- aluminosi cate and polyaluminosi cate microgel, which are both encompassed by the terms colloidal aluminium-modified silica and aluminium silicate used herein
• Clays of the smectite type that can be used in the process of the invention are known in the art and include naturally occurring, synthetic and chemically treated materials
• suitable smectite clays include montmo ⁇ llonite/bentonite, hecto ⁇ te beide te nontronite and saponite, preferably bentonite and especially such bentonite which after swelling preferably has a surface area of from 400 to 800 m 2 /g
• Suitable clays are disclosed in U S Patent Nos 4,753,710, 5,071 ,512, and 5,607,552, which are hereby incorporated herein by reference
• Anionic organic particles that can be used according to the invention include highly cross-linked anionic vinyl addition polymers, suitably copolymers comprising an anionic monomer like acrylic acid, methacrylic acid and sulfonated or phosphonated vinyl addition monomers, usually copolyme ⁇ zed with nonionic monomers like (meth)acrylam ⁇ de alkyl (meth)acrylates, etc
• Useful anionic organic particles also include anionic condensation polymers, e g melamine-sulfonic acid sols
• LMW cationic organic polymers that can be used according to the invention include those commonly referred to and used as anionic trash catchers (ATC) ATC's are known in the art as neutralizing and/or fixing agents for detrimental anionic substances present in the stock and the use thereof in combination with drainage and retention aids often provide further improved drainage and/or retention
• ATC's are known in the art as neutralizing and/or fixing agents for detrimental anionic substances present in the stock and the use thereof in combination with drainage and retention aids often provide further improved drainage and/or retention
• the 8 LMW cationic organic polymer can be derived from natural or synthetic sources, and preferably it is an LMW synthetic polymer Suitable organic polymers of this type include
• LMW highly charged cationic organic polymers such as polyamines, polyamidoamines, polyethyleneimines, homo- and copolymers based on diallyldimethyl ammonium chloride, (meth)acrylam ⁇ des and (meth)acrylates
• the molecular weight of the LMW cationic organic polymer is suitably at least 2,000 and preferably at least 10,000
• the upper limit of the molecular weight is usually about 700,000, suitably about 500,000 and preferably about
• Aluminium compounds that can be used according to this invention include alum alummates, aluminium chloride, aluminium nitrate and polyaluminium compounds, such as polyaluminium chlorides, polyaluminium sulphates, polyaluminium compounds containing both chloride and sulphate ions, polyaluminium silicate-sulphates, and mixtures thereof
• the polyaluminium compounds may also contain other anions than chloride ions for example anions from sulfunc acid, phosphoric acid, organic acids such as citric acid and oxalic acid
• the components of drainage and retention aids according to the invention can be added to the stock in conventional manner and in any order
• an LMW cationic organic polymer and/or an aluminium compound such components are preferably introduced into the stock prior to introducing the polysaccharide and anionic microparticulate material, if used
• the LMW cationic organic polymer and polysaccharide can be introduced into the stock essentially simultaneously either separately or in admixture, e g as disclosed in U S Patent No 5,858,174, which is hereby incorporated herein by reference
• the dry strength agent and drainage and retention a ⁇ d(s) according to the invention are added into the stock to be dewatered in amounts which can vary within wide limits depending on, inter alia, type and number of components, type of furnish filler content, type of filler, point of addition, salt content, etc Generally the component(s) are added in an amount that give better paper dry strength and/or drainage and/or retention than is obtained when not adding the component(s)
• the hydrophobe substituted cationic or amphoteric polysaccharide is usually added in an amount of at least 0,01 %, often at least 0,1% by weight, based on dry stock substance, and the upper limit is usually 10% and 9 suitably 2% by weight
• an anionic microparticulate material it is usually added in an amount of at least 0 001% by weight, often at least 0 005% by weight, based on dry substance of the stock, and the upper limit is usually 1 0% and suitably 0 6% by weight
• the total amount added is suitably within the range of from 0 005 to 0 5% by weight, calculated as S ⁇ 0 2 and based on dry stock substance preferably within the range of from 0 01 to 0 2% by weight
• the total amount added is suitably within the range of from 0 005 to 0 5% by weight, calculated as S ⁇ 0 2 and based on dry stock substance preferably within the range of from 0 01 to 0 2% by weight
• LMW cationic organic polymer in the process it can be added in an amount of at least
• the amount is in the range of from 0 07 to 0 5%, preferably in the range from 0 1 to 0 35%
• the total amount introduced into the stock to be dewatered is dependent on the type of aluminium compound used and on other effects desired from it It is for instance well known in the art to utilise aluminium compounds as precipitants for rosin-based sizing agents
• the total amount added is usually at least 0 05% calculated as Al 2 0 3 and based on dry stock substance
• the amount is in the range of from 0 5 to 3 0%, preferably in the range from 0 1 to 2 0%
• the process of the invention is preferably used in the manufacture of paper from a suspension containing cellulosic fibers, and optional fillers, having a high conductivity
• the conductivity of the stock that is dewatered on the wire is at least 0 75 mS/cm suitably at least 2 0 mS/cm, preferably at least 3 5 mS/cm
• Very good drainage and retention results have been observed at conductivity levels above 5 0 mS/cm and even above 7 5 mS/cm
• Conductivity can be measured by standard equipment such as for example a WTW LF 539 instrument supplied by Christian Berner
• the values referred to above are suitably determined by measuring the conductivity of the cellulosic suspension that is fed into or present in the headbox of the paper machine or, alternatively by measuring the conductivity of white water obtained by dewatering the suspension
• High conductivity levels mean high contents of salts (electrolytes), where the various salts can be based on mono-, di- and multivalent
• additives which are conventional in papermaking can of course be used in combination with the additives according to the invention, such as, for example, additional dry strength agents, wet strength agents, sizing agents, e g those based on rosin, ketene dimers and acid anhydrides, optical brightening agents, dyes, etc
• the cellulosic suspension, or stock can also contain mineral fillers of conventional types such as for example, kaolin, china clay, titanium dioxide, gypsum, talc and natural and synthetic calcium carbonates such as chalk, ground marble and precipitated calcium carbonate
• 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 sheet or web-like products, such as for example board and paperboard, and the production thereof
• the process can be used in the production of paper from different types of suspensions of cellulose-containing fibres and the suspensions should suitably contain at least 25% by weight and preferably at least 50% by weight of such fibres based on dry substance
• the suspensions can be based on fibres from chemical pulp such as sulphate sulphite and organosolv pulps, mechanical pulp such as thermomechanical pulp, chemo- 11 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 invention is particularly useful in the manufacture of paper from suspensions based on pulps comprising recycled fibres and de-inked pulp, and the content of cellulosic fibres of such origin can be up to 100%, suit
• Cationised polysaccharides were prepared by reacting native potato starch with a quaternising agent according to the general procedure described in European Patent Application No. 189 935.
• the quaternising agents are commercially available from for example Degussa, or were prepared according to the general procedure described in U.S. Patent No. 5,463,127.
• the starches were dissolved in water and used as 0.5% aqueous solutions.
• Polysaccharides according to the invention P1 to P3, and polysaccharides intended for comparison purposes, Ref. 1 and Ref. 2, were prepared from the following starting materials: P1: Cationised starch obtained by quarternisation of native potato starch with 3- chloro-2-hydroxypropyl dimethyl benzyl ammonium chloride to 0.8% N.
• P2 Cationised starch obtained by quarternisation of native potato starch with 3-chloro-
• Ref. 1 Cationised starch obtained by quarternization of native potato starch with 3- chloro-2-hydroxypropyl trimethyl ammonium chloride to 0.8% N.
• Ref. 2 Cationised starch obtained by quarternization of native potato starch with 2,3- epoxypropyl trimethyl ammonium chloride to 1.3% N.
• Analyser available from Akribi, Sweden, which 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.
• First pass retention 12 was evaluated by means of a nephelometer by measuring the turbidity of the filtrate, the white water, obtained by draining the stock.
• the furnish used was based on 56% by weight of peroxide bleached TMP/SGW pulp (80/20), 14% by weight of bleached birch/pine sulphate pulp (60/40) refined to 200° CSF and 30% by weight of china clay.
• To the stock was added 40 g/l of a colloidal fraction, bleach water from an SC mill, filtrated through a 5 ⁇ m screen and concentrated with an UF filter, cut off 200,000.
• Stock volume was 800 ml and pH about 7. Calcium chloride was added to the stock to adjust the conductivity to 5.0 mS/cm (Test Nos. 1-3), and 7.5 mS/cm (Test Nos. 4-6).
• the stock was stirred in a baffled jar at a speed of 1500 rpm throughout the test and chemicals additions were conducted as follows: i) adding polysaccharide to the stock following by stirring for 30 seconds, ii) adding anionic inorganic particles to the stock followed by stirring for 15 seconds, iii) draining the stock while automatically recording the drainage time.
• the polysaccharides used in the test series were P1 and Ref. 1 according to
• Example 1 The anionic inorganic particles used were silica-based particles of the type disclosed in U.S. Patent No. 5,368,833.
• the sol had an S-value of about 25% and contained silica particles with a specific surface area of about 900 m 2 /g which were surface-modified with aluminium to a degree of 5%.
• Table 1 shows the dewatering and retention effect at various dosages of cationized starch, calculated as dry starch on dry stock system, and silica-based particles, calculated as Si0 2 and based on dry stock system.
• the furnish was the same as used in Example 2.
• Stock volume was 800 ml and pH about 7.
• Calcium chloride was added to the stock to adjust the conductivity to 1.5 mS/cm (Test Nos. 1-3); 3.5 mS/cm (Test Nos. 4-5); and 5.0 mS/cm (Test Nos. 6-7).
• the polysaccharides used for in the test series were P2 and Ref. 2 according to Example 1.
• the anionic inorganic particles according to Example 2 were similarly used in this test series.
• Table 2 shows the dewatering effect at various dosages of drainage and retention aids, calculated as dry starch and Si0 2 on dry stock system.
• the dewatering effect was evaluated according to the procedure described in Example 2 except that the drainage and retention aids also comprised a low molecular weight cationic polyamine; ATC.
• the polyamine was added to the stock followed by stirring for 30 seconds before addition of cationized polysaccharide and then anionic inorganic particles.
• the furnish used was based on 70% deinked pulp, 15% by weight of peroxide bleached TMP/SGW pulp (80/20), and 15% by weight of bleached birch/pine sulphate pulp (60/40) refined to 200° CSF.
• Stock volume was 800 ml and pH about 7.
• Calcium chloride was added to the stock to adjust the conductivity to 1.0 mS/cm (Test No. 1), 2.0 mS/cm (Test No. 2), 4.0 mS/cm (Test Nos. 3-4) and 7.5 mS/cm (Test No 5).
• the polysaccharides used for in the test series were P1 , P2, Ref. 1 and Ref. 2 according to Example 1.
• the anionic inorganic particles according to Example 2 were similarly used.
• Table 3 shows the dewatering effect at various dosages of drainage and retention aids, calculated as dry polyamine, starch and Si0 2 on dry stock system. 14 Table 3
• Example 5 Dry strength performance was evaluated with a Dynamic Sheet Former (Formette Dynamique), supplied by Fibertech AB, Sweden, and a Tensile Strength Tester supplied by Lorentzen & Wettre, Sweden Dewatering effect was evaluated according to the procedure described in Example 4
• Example 2 The furnish according to Example 2 was used Stock consistency was 0 3% Conductivity of the stock was adjusted by addition of calcium chloride Additives and order of addition according to Example 4 were used in this test series The polyamine was added in an amount of 3 kg/ton, calculated as dry polyamine on dry stock system The silica- based particles were added in an amount of 3 kg/ton, calculated as S ⁇ 0 2 and based on dry stock system
• Paper sheets were formed in the Dynamic Sheet Former by adding the chemicals to the stock in the mixing chest, pumping the stock through a traversing nozzle into the rotating drum onto the water film on top of the wire, draining the stock to form a sheet, pressing and drying the sheet
• the sheets were cut into strips that were evaluated in the Tensile Strength Tester
• the square mean value of the tensile strength index of the machine and cross direction of the paper sheets was calculated and compared Table 4 shows the dewatering time and tensile strength of the sheets obtained at various starch dosages, calculated as dry starch on dry stock system

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• Paper (AREA)
• Polarising Elements (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Polymers With Sulfur, Phosphorus Or Metals In The Main Chain (AREA)

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