WO2008031728A1 - Procédé de fabrication du papier - Google Patents

Procédé de fabrication du papier Download PDF

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Publication number
WO2008031728A1
WO2008031728A1 PCT/EP2007/059098 EP2007059098W WO2008031728A1 WO 2008031728 A1 WO2008031728 A1 WO 2008031728A1 EP 2007059098 W EP2007059098 W EP 2007059098W WO 2008031728 A1 WO2008031728 A1 WO 2008031728A1
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WO
WIPO (PCT)
Prior art keywords
paper
cationic
thin stock
stock
starch
Prior art date
Application number
PCT/EP2007/059098
Other languages
English (en)
Inventor
Sakari Saastamoinen
Eduard Virolainen
Original Assignee
Ciba Holding Inc.
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
Priority claimed from GB0618177A external-priority patent/GB0618177D0/en
Priority claimed from GB0623284A external-priority patent/GB0623284D0/en
Application filed by Ciba Holding Inc. filed Critical Ciba Holding Inc.
Publication of WO2008031728A1 publication Critical patent/WO2008031728A1/fr

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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
    • 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
    • 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
    • D21H17/63—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
    • D21H23/76—Processes or apparatus for adding material to the pulp or to the paper characterised by choice of auxiliary compounds which are added separately from at least one other compound, e.g. to improve the incorporation of the latter or to obtain an enhanced combined effect
    • D21H23/765—Addition of all compounds to the pulp
    • 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
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/10—Packing paper

Definitions

  • the present invention concerns a process for making sack paper, paper for making paper bags, single layer kraft papers and high porosity paper.
  • the process provides benefits in improved porosity without compromising strength, drainage, retention and formation.
  • sack paper paper for making bags and high porosity paper tends to be produced without the use of any retention chemicals.
  • Typically such paper including sack paper would be produced using furnish grinding and slow dewatering in the wire section. It is essential that the sack paper has sufficient porosity to allow the passage of air in order to allow the bag or sack to be filled. High porosity can also be important for single layer kraft papers.
  • Porosity of porous packaging material is generally determined using a Gurley densitometer or alternatively by a devise called a Bendtsen tester.
  • the Gurley tester determines the time for 100 cm 3 of air to flow through a one square inch area of test material, under a pressure gradient of 1.22 kPa. It is usually desirable for high porous sack paper to exhibit a Gurley value of below 10 seconds and in some cases significantly below this, for instance as low as 5 seconds.
  • the finished sack paper may be machine treated by forming pinholes in it mechanically.
  • the mechanical treatment of the sack paper can sometimes damage the paper.
  • this treatment of the paper will normally require additional processing time and associated energy costs.
  • Korean utility model registration number 1985-1644 provides an alternative method for providing sacks with the appropriate level of porosity and describes a sack manufactured by interposing a synthetic resin film formed with vents between plies of kraft paper and then heat sealing them. Apart from the risk of deterioration of the contents the construction of the sacks is elaborate. In this disclosure there is no description as to how the kraft paper is made.
  • WO99/02772 sets out to provide a method which produces kraft paper useful for sack production which has an exceptional combination of tensile energy absorption index and porosity.
  • the kraft paper is made by subjecting sulphate or kraft pulp to high consistency refining only or high consistency refining in combination with low consistency beating maintained at a value of below 80 kWh per tonne of finished paper based on dry weight of paper.
  • the process also requires the addition of a strengthening agent to the stock obtained at one or more points in the process prior to feeding onto the wire of the paper machine. Starch is described as a suitable strengthening agent. It is stated that high porosity is achieved with Gurley porosity values of less than 10 seconds and more specifically of five seconds.
  • US 4741376 provides a process for manufacturing of kraft paper, especially Kraft sack paper, with improved strength properties. The process involves them by forming the paper web into two or more layers which are couched together in the wire section of the machine and then shrunk in order to obtain a high- strength. No mention of the use of drainage aids or retention aids is given.
  • US 4409065 describes a process for making kraft paper particularly suitable for packaging materials such as paper bags or sacks.
  • the process involves taking beaten pulp referred to as refined pulp which undergoes the last additional separate curlation which is preferably carried out in a Kollergang or other equipment causing a similar effect. No mention of using retention or drainage aids is given.
  • US 4305781 describes a method for producing paper and is said to be suitable for preparing kraft paper, fluting medium or newsprint.
  • the process involves using bentonite and a substantially non-ionic polymer in a substantially unfilled paper pulp.
  • the substantially non-ionic polymer is wholly non-ionic but can be up to 10 mole% anionic or up to 10 mole% cationic.
  • the polymer and bentonite can be added in any order but preferably the bentonite is added first, kraft paper can be used in a variety of packaging applications such as cardboard boxes and is not necessarily suitable for making sacks.
  • Producing paper suitable for making sacks, bags or single layer kraft papers is not mentioned and nor is any indication given that the paper and thus obtained would have a high porosity.
  • a process of making sack paper, paper for making bags or single layer kraft papers having improved porosity comprising forming a paper furnish thick stock suitable for making sacks, bags or single layer kraft paper, diluting the thick stock to form a thin stock, flocculating the thin stock, draining the thin stock on a screen to form a sheet and then drying the sheet, flocculating the thin stock by adding a flocculating system to the thin stock, wherein the flocculating system comprises a synthetic polymer of weight average molecular weight at least 500,000 Daltons which is either cationic or amphoteric and a siliceous material, and in which a soluble starch is added to the thin stock or prior to the thin stock.
  • the thin stock is flocculated by adding the synthetic polymer of weight average molecular weight at least 500,000 Daltons which is either cationic or amphoteric to form a flocculated suspension, subjecting the flocculated suspension to mechanical degradation, and then reflocculating by adding the siliceous material.
  • the siliceous material may be more desirable to add the siliceous material to the thin stock thereby bringing about flocculation, subjecting this flocculated suspension to mechanical degradation, and then reflocculating by adding the synthetic polymer of weight average molecular weight at least 500,000 Daltons which is either cationic or amphoteric.
  • the present invention also relates to sack paper produced according to this process.
  • the present invention also relates to paper bags or single layer kraft paper made by this process.
  • this process provides sack paper, bag paper and single layer kraft paper having especially high porosity without compromising strength, formation, drainage and retention. Gurley values of below 10 seconds can easily be achieved without necessarily using mechanical means for treating the finished sack, bag or single layer kraft paper. The inventors believe that it has previously not been possible to achieve such high porosities by chemical means alone.
  • the process appears to provide a more open structure by comparison to using an alternative retention system. Without being limited to theory it is thought that this may be responsible for the improved porosity and combination of acceptable strength, drainage, retention and formation.
  • the strength can usually be maintained by conventional adjustment of the furnish in terms of low and high consistency refining.
  • reducing refining load reduces fibre cutting and fibrillation. This means that less fines are created. Fibres remain course (less fibrillation) and is believed to facilitate the formation of a more porous structure.
  • high levels of refining tend increased the level of fines and also to reduce the strength of the sheet.
  • the soluble starch employed in the present invention may be any suitable starch that this substantially or wholly soluble in water.
  • This starch may be derived from potato starch, maize starch, wheat starch, rice starch, corn starch, tapioca starch and any other commercially available starch.
  • the starch is wholly soluble in water, in that it will exhibit a solubility of at least 5 g in 100 cc of water at 25°C.
  • the starch can be rendered at least partially soluble but otherwise unmodified but preferably it is modified by being dehvatised.
  • Soluble starch may be non- ionic or anionic but preferably it is either cationic starch or amphoteric starch.
  • Most preferably the soluble starch is cationic starch.
  • the cationic starch may have a degree of ionic substitution of between 0.01 and 0.3 or considerably higher. The degree of substitution may be between 0.01 and 0.2.
  • Starch can be dry or wet modified.
  • the soluble starch may be added in any convenient amount, for instance at least 50 g per tonne and usually considerably higher, such as at least 400 or 500 grams per tonne based on dry weight of suspension. It may be added in an amount up to 5 kg per tonne or even higher. Often it will be added at between 1 and 3 kg per tonne.
  • the starch may be added into thin stock suspension or alternatively prior to dilution for example into the thick stock. In some cases it may be desirable to add the starch further back in the papermaking process, for instance into the blend chest or the mixing chest. Preferably the starch is added into the thin stock and more preferably this would be prior to the centriscreen. In some cases in may be desirable to add the starch to the thin stock after the centriscreen.
  • the synthetic polymer may be any suitable cationic or amphoteric synthetic polymer which has a weight average molecular weight of at least 500,000.
  • the cationic or amphoteric polymers may be a conventional polymer used in papermaking processes as retention or drainage aids.
  • the polymer may be linear, cross-linked or otherwise structured, for instance branched.
  • Preferably the polymer is water-soluble.
  • the polymer can be any of the group consisting of substantially water-soluble cationic and amphoteric polymers.
  • the polymers may prepared by polymerising water-soluble ethylenically unsaturated monomers such as acrylamides, acrylic acid, alkali metal or ammonium acrylates or quaternised dialkyl amino alkyl- (meth) acrylates or -(meth) acrylamides.
  • the polymers will have weight average molecular weights ranging from at least one million up to 20 or 30 million or higher. Typically the polymers will have weight average molecular weights between 5 and 15 million.
  • the polymer may be provided in any suitable and commercially available form, including bead, powder or reverse phase emulsion or dispersion.
  • Water-soluble synthetic polymers may be derived from any water soluble monomer or monomer blend.
  • water soluble we mean that the monomer has a solubility in water of at least 5g/100cc at 25°C. In general the water-soluble polymers will satisfy the same solubility criteria.
  • the ionic content of the polymer is low to medium.
  • the charge density of the ionic polymer may be below 5 meq/g, preferably below 4, especially below 3 meq/g.
  • the ionic polymer may comprise up to 50% by weight ionic monomer units although in some applications higher levels of ionic monomer, for instance at 100% may be used.
  • the synthetic polymer may be formed from a monomer mixture comprising acrylamide and a cationic monomer.
  • the polymer When the polymer is cationic it may contain acrylamide with one or more cationic monomers.
  • the monomers mixture comprising acrylamide and a cationic monomer or monomers will additionally comprise at least one anionic monomer.
  • the preferred cationic water soluble polymers have cationic or potentially cationic functionality.
  • the cationic polymer may comprise free amine groups which become cationic once introduced into a cellulosic suspension with a sufficiently low pH so as to protonate the free amine groups. More preferably however, the cationic polymers carry a permanent cationic charge, such as quaternary ammonium groups.
  • the polymer may be formed from a water soluble ethylenically unsaturated cationic monomer or blend of monomers wherein at least one of the monomers in the blend is cationic.
  • the cationic monomer is preferably selected from di allyl di alkyl ammonium chlorides, acid addition salts or quaternary ammonium salts of either dialkyl amino alkyl (meth) acrylates or dialkyl amino alkyl (meth) acrylamides.
  • the cationic monomer may be polymerised alone or copolymerised with water soluble non-ionic, cationic or anionic monomers.
  • Particularly preferred cationic polymers include polymers of methyl chloride quaternary ammonium salts of dimethylaminoethyl acrylate or methacrylate especially copolymers of these monomers with acrylamide. Particularly preferred polymers include copolymers of methyl chloride quaternised dimethyl amino ethyl acrylate with acrylamide.
  • the cationic polymer may comprise only cationic monomer units or alternatively may only comprise relatively small amounts of cationic monomer, for instance 1 % by weight or less. Generally the cationic polymer comprises at least 5% cationic monomer units and usually at least 10% by weight cationic monomer units. Often the cationic polymer may comprise up to 90 or 95% by weight cationic monomer units.
  • Preferred cationic polymers comprise between 20 and 80% by weight cationic monomer and more preferably 40 to 60% by weight cationic monomer units.
  • the amphoteric polymer When the polymer is amphoteric it will comprise both anionic or potentially anionic and cationic or potentially cationic functionality.
  • the amphoteric polymer may be formed from a mixture of monomers of which at least one is cationic or potentially cationic and at least one monomer is anionic or potentially anionic and optionally at least one nonionic monomer is present. Suitable monomers would include any of the cationic, anionic and nonionic monomers given herein.
  • a preferred amphoteric polymer would be a polymer of acrylic acid or salts thereof with methyl chloride quaternised dimethyl amino ethyl acrylate and acrylamide.
  • the amphoteric polymer may comprise relatively small amounts of anionic and cationic monomer units, for instance 1 % by weight or less of each. However, generally the amphoteric polymer will comprise at least 5% anionic monomer units and at least 5% by weight cationic monomer units, In some cases it may be desirable to have more of one ionic monomer than the other. For instance it may be desirable to have a greater amount of cationic monomer than anionic monomer. Usually the amphoteric polymer comprises at least 10% by weight cationic monomer units and often greater than 20 or 30% cationic units. Preferably the amphoteric polymer comprises between 20 and 80% by weight cationic monomer units and more preferably 40 to 60% by weight cationic monomer units. The amphoteric polymer may comprise at least 20 or 30% anionic monomer units. It may be desirable for the amphoteric polymer to comprise at least 40 or 50% by weight anionic units.
  • the synthetic polymer may be produced by any conventional means, for instance as a bead, powder, reverse phase emulsion or a reverse phase dispersion.
  • the polymers may be produced by for instance the processes described in any of EP-A-150933, EP-A-102760 or EP-A-126528.
  • the siliceous material may be any of the materials selected from the group consisting of silica based particles, silica microgels, colloidal silica, silica sols, silica gels, polysilicates, cationic silica, aluminosilicates, polyaluminosilicates, borosilicates, polyborosilicates, zeolites, precipitated metal silicates and swelling clays.
  • This siliceous material may be in the form of an anionic microparticulate material.
  • the siliceous material may be a cationic silica.
  • the siliceous material is anionic.
  • the siliceous material is selected from silicas and polysilicates.
  • the silica may be any colloidal silica, for instance as described in WO-A-8600100.
  • the polysilicate may be a colloidal silicic acid as described in US-A-4,388,150.
  • the polysilicates of the invention may be prepared by acidifying an aqueous solution of an alkali metal silicate.
  • polysilicic microgels otherwise known as active silica may be prepared by partial acidification of alkali metal silicate to about pH 8-9 by use of mineral acids or acid exchange resins, acid salts and acid gases. It may be desired to age the freshly formed polysilicic acid in order to allow sufficient three dimensional network structure to form. Generally the time of ageing is insufficient for the polysilicic acid to gel.
  • Particularly preferred siliceous materials include polyalumino-silicates.
  • the polyaluminosilicates may be for instance aluminated polysilicic acid, made by first forming polysilicic acid microparticles and then post treating with aluminium salts, for instance as described in US-A-5, 176,891.
  • Such polyaluminosilicates consist of silicic microparticles with the aluminium located preferentially at the surface.
  • the polyaluminosilicates may be polyparticulate microgels of surface area in excess of 1000m 2 /g formed by reacting an alkali metal silicate with acid and water soluble aluminium salts, for instance as described in US-A- 5,482,693.
  • the polyaluminosilicates may have a mole ratio of alumina:silica of between 1 :10 and 1 : 1500.
  • Polyaluminosilicates may be formed by acidifying an aqueous solution of alkali metal silicate to pH 9 or 10 using concentrated sulphuric acid containing 1.5 to 2.0% by weight of a water soluble aluminium salt, for instance aluminium sulphate.
  • the aqueous solution may be aged sufficiently for the three dimensional microgel to form.
  • the polyaluminosilicate is aged for up to about two and a half hours before diluting the aqueous polysilicate to 0.5 weight % of silica.
  • the siliceous material may be a colloidal borosilicate, for instance as described in WO-A-9916708.
  • the colloidal borosilicate may be prepared by contacting a dilute aqueous solution of an alkali metal silicate with a cation exchange resin to produce a silicic acid and then forming a heel by mixing together a dilute aqueous solution of an alkali metal borate with an alkali metal hydroxide to form an aqueous solution containing 0.01 to 30 % B 2 O 3 , having a pH of from 7 to 10.5.
  • the siliceous material is a silica
  • the siliceous material is a silica or silicate type material it has a particle size in excess of 10 nm. More preferably the silica or silicate material has a particle size in the range 20 to 250 nm, especially in the range 40 to 100 nm.
  • the siliceous material is a swelling clay.
  • the swellable clays may for instance be typically a bentonite type clay. This will include smectites and other generally swellable clays.
  • the preferred clays are swellable in water and include clays which are naturally water swellable or clays which can be modified, for instance by ion exchange to render them water swellable.
  • the clay may be a natural clay or alternatively could be a synthetic clay, for instance a synthetic or natural hectorite.
  • Suitable water swellable clays include but are not limited to clays often referred to as hectorite, smectites, montmohllonites, nontronites, saponite, sauconite, hormites, attapulgites and sepiolites.
  • Typical anionic swelling clays are described in EP-A-235893 and EP-A-335575.
  • the clay is a bentonite type clay.
  • the bentonite may be provided as an alkali metal bentonite. Bentonites occur naturally either as alkaline bentonites, such as sodium bentonite or as the alkaline earth metal salt, usually the calcium or magnesium salt. Generally the alkaline earth metal bentonites are activated by treatment with sodium carbonate or sodium bicarbonate. Activated swellable bentonite clay is often supplied to the paper mill as dry powder. Alternatively the bentonite may be provided as a high solids flowable slurry of activated bentonite, for example at least 15 or 20% solids, for instance as described in EP-A-485124, WO-A-9733040 and WO-A-9733041.
  • the bentonite may be applied to the cellulosic suspension as an aqueous bentonite slurry.
  • the bentonite slurry comprises up to 10% by weight bentonite.
  • the bentonite slurry will normally comprise at least 3% bentonite clay, typically around 5% by weight bentonite.
  • the slurry is diluted to an appropriate concentration.
  • the high solids flowable slurry of bentonite may be applied directly to the paper making stock.
  • the siliceous material is applied in an amount of at least of at least 100 ppm by weight based on dry weight of suspension.
  • the dose of siliceous material may be as much as 40,000 ppm by weight or higher. In one preferred aspect of the invention doses of 100 to 500 ppm by weight have been found to be effective. Alternatively higher doses of siliceous material may be preferred, for instance 1000 to 2000 ppm by weight.
  • the swellable clay is added as an aqueous slurry. This may be provided by mixing dry powdered swellable clay into water, for instance using a make up apparatus. Alternatively a concentrated slurry of swellable clay as supplied may be diluted to the appropriate concentration. Typically, the swellable clay would be added at any suitable concentration that would allow easy handling and adequate distribution throughout the papermaking stock. Usually the swellable clay is used at a dose of at least 200 g clay solids per tonne of papermaking stock calculated by dry basis. Typically as much as 20 kg per tonne (swellable clay on dry suspension) may be added. Preferred doses are generally between 1 kg per tonne and 4 kg per tonne.
  • the thin stock suspension may be flocculated by the addition of the synthetic polymer to provide a flocculated suspension.
  • the flocculated suspension may contain loose open flocks which tend to be less stable.
  • This flocculated suspension is then subjected to mechanical degradation which tends to break down the flocculated structure.
  • the mechanical degradation can be achieved by means selected from mixing, cleaning and screening stages.
  • Such mechanical degradation results from parts of the process that provide a shearing action.
  • Preferred forms include passing the suspension through a fan pump or centriscreen.
  • the mechanically degraded suspension should then be re flocculated by the addition of the swellable clay.
  • the action of the swellable clay on the suspension brings about an aggregation of the suspended solids so that the re flocculated structure tends to be more stable.
  • the cationic or amphoteric polymer may be added before one of the shear stages that brings about degradation of the flocculated structure and the siliceous material, such as swellable clay, should be added after that stage.
  • the synthetic polymer may be added before one of the fan pumps and a siliceous material, such as swellable clay, added after that fan pump which may be after that fan pump but prior to any subsequent fan pump or prior to the centriscreen, provided that the swellable clay is added after mechanical degradation of the flocculated structure has occurred.
  • the siliceous material such as swellable clay
  • the synthetic polymer can be added prior to one or more of the fan pumps but preferably is added between the fan pump or last fan pump but before the centriscreen and the siliceous material, especially swellable clay, is added after the centriscreen.
  • a particularly preferred form of the invention employs a cationic starch and cationic polyacrylamide which are added to the thin stock prior to the centriscreen and in which the siliceous material, especially swellable clay, is added after the centriscreen.
  • the cationic starch and polyacrylamide may be added in either order, but preferably the cationic starch is added first.
  • the siliceous material especially swellable clay e.g. bentonite
  • the siliceous material may be added to the thin stock before a shear stage, for instance prior to one or more of the fan pumps but preferably is added between the fan pump or last fan pump but before the centriscreen and the cationic or amphoteric polymer is added after that shear stage, preferably immediately after that shear stage and more preferably after the centriscreen.
  • the soluble starch, especially cationic starch may be added before any of the shear stages are alternatively after any one on the shear stages. For instance it may be added before the centriscreen or alternatively after the centriscreen.
  • the process enables sack, bag or single layer kraft paper to be produced in the absence of mechanical perforation or pulp grinding.
  • kraft paper has been found to exhibit Gurley values of below 10 seconds and more preferably we have found that the process can result in Gurley values of below 7 seconds, especially below 6 seconds and even as low as 5 seconds or less.
  • the following examples demonstrate producing sack paper on a moving belt former (MBF).
  • the cationic polyacrylamide is a copolymer of acrylamide with dimethyl amino acrylate, methyl chloride quaternary salt of intrinsic viscosity > 7 dl/g.
  • the chemical dosages of above Table 1 are based on the active material.
  • Starch and cationic polyacrylamide have been dosed at pre centriscreen addition. Microparticles, colloidal silica and bentonite were dosed as post screen addition.
  • Starch (Raisamyl 70021 ) cationic polyacrylamide and colloidal silica have all been dosed in this furnish.
  • Dewatering rate has been recorded as vacuum pressure during moving belt former test. The lower the vacuum curve goes, the faster the dewatering. Formation has been measured as Beta formation - again the lower the value, the more uniform the sheet is. Gurley value has been based on 100 ml of air volume flowing through the sheet. The lower the reading, the more open the structure is. An open structure is generally desired with certain higher quality sack paper grades. The so called 5 second sack is target for example is cement sack filling because in 5 seconds air has to get through the holes of sack paper in order to have full sack paper machine capacity utilized. All values are an average value of ten measurements.
  • Moving Belt Former is a sheet former type lab scale equipment, which forms paper sheet under vacuum and pulsation effects (moving belt with foils).
  • the formed sheet has typical fourdrinier type filler distribution. The extra benefits of these are that it gives a sheet where sheet properties can be measured and it gives the total dewatering effect, not just so called free drainage performance.
  • Figure 1 shows how dewatering rate varies between the different chemical combinations. 5 kg/t Starch used alone gives the slowest dewatering rate. Since single starch addition has such a reduced (i.e. slower) dewatering rate, its dewatering performance has not been included in Figure 2. The remaining results are shown in Figure 2.
  • the fastest dewatering performance is when using Starch, cationic polyacrylamide (PAM) and bentonite combinations. Addition points using cationic polyacrylamide pre screen with bentonite post screen using different doses of bentonite exhibit the second fastest dewatering rates. Use of cationic polyacrylamide alone is shown. Starch and bentonite treatment are shown and Starch and colloidal silica are shown and do not have the same dewatering performance. Starch, cationic polyacrylamide and colloidal silica combination has generally about the same dewatering rate as the systems that just employ cationic polyacrylamide and bentonite.
  • Table 2 above shows first pass retention, formation and Gurley values of the MBF produced sheets.
  • First pass retention of Single Starch (H), Starch & colloidal silica (A) and Starch and Bentonite (B) have the lowest first pass retention values.
  • Cationic polyacrylamide and bentonite (D and E), single cationic polyacrylamide (F) and the both three components retention combinations (C and G) have the best first pass retention performance. Slightly better formation than on the other trial points is reached with three component combinations of Starch and cationic polyacrylamide and bentonite (C).
  • Cationic polyacrylamide used alone (F) gives slightly worse formation than the others.
  • Starch dosed in thin furnish together with cationic polyacrylamide and bentonite (trial point C) is the only combination which gives an open enough structure which enables the so called 5 seconds sack to be achieved.
  • Addition points (D and E), Starch with bentonite and Starch with cationic polyacrylamide with colloidal silica do not provide as porous a structure as for the bentonite.
  • Gurley values are really modified Gurley values. This is due to the fact that MBF does not generate exactly the same structure as in a real production machine.
  • Modified Gurley (mod. Gurley) are the Gurley values multiplied with 6.7 and rounded to the closest integer. The multiplier comes from the fact that Gurley value measured from the sheet without any retention aids gives the reading 3.
  • WEX commercial sack paper grades, without any retention aid had Gurley value about 20 in the paper machine.
  • the factor 6.7 is based on the following calculation: 20 ⁇ 3 equals to 6.7. This relationship is determined using a specific paper machine and specific moving belt former and is not a universal relationship between laboratory tests and paper mill paper machines.

Landscapes

  • Paper (AREA)
  • Laminated Bodies (AREA)

Abstract

La présente invention concerne un procédé de fabrication de papier à sac, de papier approprié pour fabriquer des sacs ou du papier kraft monocouche ayant une porosité améliorée, le procédé comprenant l'étape consistant à former une pâte épaisse de composition de fabrication de papier pour fabriquer des sacs-ballots, des sacs ou du papier kraft monocouche, la dilution de la pâte épaisse pour former une pâte mince, la floculation de la pâte mince, l'écoulement de la pâte mince sur un écran pour former une feuille puis le séchage de la feuille, la pâte mince étant floculée par addition d'un système de floculation à la pâte mince, le système de floculation comprenant un polymère synthétique de poids moléculaire moyen d'au moins 500 000 Daltons qui est soit cationique soit amphotère et d'une matière siliceuse, et dans lequel un amidon soluble est ajouté à la pâte mince ou avant la pâte mince. L'invention concerne également du papier pour sacs-ballots, du papier pour sac et du papier kraft monocouche fabriqué par le procédé.
PCT/EP2007/059098 2006-09-15 2007-08-31 Procédé de fabrication du papier WO2008031728A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB0618177.0 2006-09-15
GB0618177A GB0618177D0 (en) 2006-09-15 2006-09-15 Process of manufacturing paper
GB0623284.7 2006-11-22
GB0623284A GB0623284D0 (en) 2006-11-22 2006-11-22 Process of manufacturing paper

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WO2008031728A1 true WO2008031728A1 (fr) 2008-03-20

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AR (1) AR062788A1 (fr)
TW (1) TW200840911A (fr)
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2929963A1 (fr) * 2008-04-10 2009-10-16 Snf Sas Soc Par Actions Simpli Procede de fabrication de papier et carton
EP2963178A1 (fr) * 2014-07-04 2016-01-06 BillerudKorsnäs AB Production d'un papier d'ensachage

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4305781A (en) * 1979-03-28 1981-12-15 Allied Colloids Limited Production of newprint, kraft or fluting medium
WO1997033041A1 (fr) * 1996-03-08 1997-09-12 Allied Colloids Limited Compositions a base d'argile et leur utilisation dans la fabrication du papier
EP1039026A1 (fr) * 1994-06-01 2000-09-27 Ciba Specialty Chemicals Water Treatments Limited Fabrication de papier
WO2000075074A1 (fr) * 1999-06-02 2000-12-14 Nalco Chemical Company Sols de silice stables a aire de surface elevee et activite amelioree
US20010023752A1 (en) * 1997-09-30 2001-09-27 Keiser Bruce A. Method of increasing drainage in papermaking using colloidal borosilicates
EP1138824A1 (fr) * 2000-03-23 2001-10-04 Mpc Formulation d'adjuvants pour l'industrie papetière et procédé de mise en oeuvre d'une telle formulation
US20030024671A1 (en) * 1999-05-04 2003-02-06 Michael Persson Silica-based sols
US20050228057A1 (en) * 2004-04-07 2005-10-13 Johan Nyander Silica-based sols and their production and use

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4305781A (en) * 1979-03-28 1981-12-15 Allied Colloids Limited Production of newprint, kraft or fluting medium
EP1039026A1 (fr) * 1994-06-01 2000-09-27 Ciba Specialty Chemicals Water Treatments Limited Fabrication de papier
WO1997033041A1 (fr) * 1996-03-08 1997-09-12 Allied Colloids Limited Compositions a base d'argile et leur utilisation dans la fabrication du papier
US20010023752A1 (en) * 1997-09-30 2001-09-27 Keiser Bruce A. Method of increasing drainage in papermaking using colloidal borosilicates
US20030024671A1 (en) * 1999-05-04 2003-02-06 Michael Persson Silica-based sols
WO2000075074A1 (fr) * 1999-06-02 2000-12-14 Nalco Chemical Company Sols de silice stables a aire de surface elevee et activite amelioree
EP1138824A1 (fr) * 2000-03-23 2001-10-04 Mpc Formulation d'adjuvants pour l'industrie papetière et procédé de mise en oeuvre d'une telle formulation
US20050228057A1 (en) * 2004-04-07 2005-10-13 Johan Nyander Silica-based sols and their production and use

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2929963A1 (fr) * 2008-04-10 2009-10-16 Snf Sas Soc Par Actions Simpli Procede de fabrication de papier et carton
WO2009136024A2 (fr) * 2008-04-10 2009-11-12 Snf S.A.S. Procédé de fabrication de papier et carton
WO2009136024A3 (fr) * 2008-04-10 2009-12-30 Snf S.A.S. Procédé de fabrication de papier et carton
EP2963178A1 (fr) * 2014-07-04 2016-01-06 BillerudKorsnäs AB Production d'un papier d'ensachage
WO2016001028A1 (fr) * 2014-07-04 2016-01-07 Billerudkorsnäs Ab Production de papier à sacs
RU2676290C2 (ru) * 2014-07-04 2018-12-27 Биллерудкорснес Аб Производство мешочной бумаги
RU2676290C9 (ru) * 2014-07-04 2019-03-13 Биллерудкорснес Аб Производство мешочной бумаги
AU2015282800B2 (en) * 2014-07-04 2019-05-16 Billerudkorsnas Ab Production of sack paper
US10458070B2 (en) 2014-07-04 2019-10-29 Billerudkorsnäs Ab Production of sack paper

Also Published As

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TW200840911A (en) 2008-10-16
AR062788A1 (es) 2008-12-03

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