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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/38—Coatings with pigments characterised by the pigments
  • D21H19/40—Coatings with pigments characterised by the 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
  • D21H21/14—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 characterised by function or properties in or on the paper

Definitions

• the invention relates to a process of producing a cellulosic fibre web which may be further processed to air-laid paper, tissue or fluff.
• the invention also relates to a cellulosic fibre web obtainable from the process and air-laid paper, tissue, or fluff obtainable by further processing of the cellulosic fibre web.
• WO 2007/058609 discloses a process in which the static potential of the fibres/paper product can be controlled and reduced while enhancing the softness of the produced paper product. However, it is desirable to further control the static potential. Also, it is desirable to obtain uniform spreading/dispersion of an antistatic agent. A further object is to increase the retention and effective use of an antistatic agent.
• a further object is to provide a process in which a relatively low dosage of an antistatic additive(s) can reduce the static potential to an acceptable level. It is a further object to improve the antistatic effect with a combination of antistatic agents so as to provide a smooth and relatively quick process of reducing and controlling the static potential.
• the present invention relates to a process of producing a cellulosic fibre web comprising
• polymers added to the cellulosic fibre web in particular cationic polymers, can contribute to an increase in static potential.
• cellulosic fibre web includes any sheet or web prepared from cellulosic fibres such as pulp sheets or paper webs.
• Colloidal silica particles may be derived from e.g. precipitated silica, micro silica (silica fume), pyrogenic silica (fumed silica) or silica gels with sufficient purity, and mixtures thereof.
• the silica particles are silanised as described in WO2004/035474.
• the silica sol may also, typically, be produced from waterglass as raw material as disclosed in e.g. U.S. Pat. No. 5,368,833.
• colloidal silica particles and silica sols according to the invention may be modified and can contain other elements such as amines, aluminium and/or boron, which can be present in the particles and/or the continuous phase.
• Boron-modified silica sols are described in e.g. U.S. Pat. No. 2,630,410.
• the aluminium modified silica particles suitably have an Al 2 O 3 content of from about 0.05 to about 3 wt %, for example from about 0.1 to about 2 wt %.
• the procedure of preparing an aluminium modified silica sol is further described in e.g. “The Chemistry of Silica”, by Iler, K. Ralph, pages 407-409, John Wiley & Sons (1979) and in U.S. Pat. No. 5,368,833.
• the colloidal silica particles suitably have an average particle diameter ranging from about 2 to about 150, for example from about 3 to about 50, or from about 5 to about 40 nm.
• the colloidal silica particles have a specific surface area from about 20 to about 1500, for example from about 50 to about 900, or from about 70 to about 600 m 2 /g.
• the anionic colloidal silica particles are hydrophobically modified.
• colloidal silica particles are added to the formed cellulosic fibre web in an amount from about 0.01 to about 2, or from about 0.1 to about 2, or from about 0.1 to about 1, or from about 0.1 to about 0.75, or from about 0.1 to about 0.5 kg/t dry cellulosic fibres. According to one embodiment, from about 0.1 to about 5 kg, or from about 0.25 to about 1, or from about 0.25 to about 0.75, or from about 0.25 to about 0.5 kg colloidal silica particles/t dry cellulosic fibres are added to the cellulosic fibre web.
• no further component is added separately or in conjunction with the colloidal silica particles to the formed cellulosic fibre web.
• no or substantially no silicate compound and/or no wet strength agent is added to the cellulosic fibre web.
• a smectite clay is added to the formed web.
• the smectite clay can be added in an amount from about 0.01 to about 50, for example from about 0.02 to about 10 or from about 0.1 to about 5 or from about 0.2 to about 2 or from about 0.25 to about 0.75 kg/ton dry cellulosic fibres.
• the smectite clay is present in an aqueous dispersion.
• the smectite clay for example in dispersion form, is sprayed on the web.
• smectite clays which can be used according to the present invention include for example montmorillonite/bentonite, hectorite, beidelite, nontronite, saponite, and mixtures thereof.
• the smectite clay is laponite and/or bentonite.
• the smectite clay can be modified e.g. by introducing a cation or a cationic group, such as a quaternary ammonium group or an alkali metal, for example lithium.
• a cation or a cationic group such as a quaternary ammonium group or an alkali metal, for example lithium.
• the smectite clay is a synthetic hectorite clay modified with lithium.
• This clay is sold under the name Laponite® from Rockwood or Eka Soft F40 from Eka Chemicals AB.
• Examples of such clays, and the manufacturing of such clays, include those disclosed in WO 2004/000729.
• the smectite clay used according to the present invention can have a specific surface area from about 50 to about 1500, for example from about 200 to about 1200, or from about 300 to about 1000 m 2 /g.
• Suitable products may be for example Bentonite from Süd-Chemie, BASF and Clayton; Bentolite (Bentonite) from Southern Clay Products; and Hydrotalcite from Akzo Nobel.
• the smectite clay can be applied by immersion of the cellulosic fibre web into a solution or dispersion of the smectite clay.
• the aqueous dispersion of smectite clay can either be produced in advance or dispersed on site.
• the smectite clay is added as a powder.
• smectite clay is added to the cellulosic suspension, for example in an amount of from about 0.01 to about 10, such as from about 0.05 to about 5, or from about 0.1 to about 2 or from about 0.25 to about 1 kg/ton dry cellulosic fibres.
• the weight ratio of smectite clay added to the cellulosic suspension and smectite clay added to the cellulosic fibre web ranges from about 1:100 to about 100:1 for example from about 5:95 to about 80:20, or from about 10:90 to about 50:50, or from about 15:85 to about 40:60 or from about 20:80 to about 30:70.
• a debonder system such as a debonder composition is added to the suspension.
• a debonder composition may comprise one or several components in a mixture which is added jointly or in conjunction to the cellulosic suspension
• a debonder system may also involve one or several components which are added separately to the cellulosic suspension.
• a debonder system is added as a pre-mixed emulsion further comprising a polymer as defined herein.
• the weight ratio of the debonder system, including the total weight of the components being part of the debonder system, to smectite clay added to the cellulosic fibre web ranges from about 1:50 to about 100:1, for example from about 1:10 to about 50:1 or from about 1:5 to about 20:1, or from about 1:2 to about 10:1, or from about 1:1 to about 5:1.
• the weight ratio of the debonder system to silica particles added to the cellulosic fibre web ranges from about 1:50 to about 100:1, for example from about 1:10 to about 50:1 or from about 1:5 to about 20:1, or from about 1:2 to about 10:1, or from about 1:1 to about 5:1.
• the debonder system comprises
• the debonder system comprises at least one quaternary ammonium surfactant.
• refined and/or hydrogenated grade oils for example vegetable oils like grape oil, olive oil, coconut oil, rape seed oil, sunflower oil and palm oil, for example coconut oil is comprised in the debonder system.
• mineral oils and/or silicon oil are comprised in the debonder system.
• the debonder system is free or substantially free from quaternary ammonium surfactants.
• substantially free is meant that quaternary ammonium surfactants constitute less than 5 wt %, for example less than 1, or less than 0.5 wt % of the total amount of the debonder system.
• the debonder system i.e. the total amount of component(s) making up the system, is added in an amount from about 0.1 to about 10, for example from about 0.3 to about 7, or from about 0.5 to about 5 kg/ton dry cellulosic fibres.
• a preserving agent may be added.
• cosmetic additives can also be included, for example antioxidants, e.g. tocopherol, and aloe vera.
• the cellulosic fibre web is further processed to produce air-laid paper, tissue or fluff.
• the present invention also relates to a cellulosic fibre web obtainable by the process as described herein.
• the present invention also relates to a cellulosic fibre web comprising silica particles in an amount from about 0.25 to about 1 kg/ton dry cellulosic fibres, or from about 0.25 to about 0.75 kg/ton dry cellulosic fibres wherein the static potential is lower than 5 kV.
• the weight ratio of silica particles added to the web and smectite clay added to the web ranges from about 1:100 to about 100:1 for example from about 1:50 to about 50:1, or from about 1:20 to about 25:1, or from about 1:5 to about 10:1, or from about 1:2 to about 4:1, or from about 1:1 to about 2:1.
• the static potential of the cellulosic fibre web is lower than 10, or lower than 8, or lower than 6, or lower than 5 kV.
• the defiberization energy of the cellulosic fibre web is lower than 120, such as lower than 110 or lower than 100 kJ/kg.
• the cellulosic fibre web has a dry content of from about 5 to about 99, for example from about 25 to about 95 or from about 50 to about 95 or from about 65 to about 95 or from about 80 to about 95 wt % based on the total weight of the web.
• the cellulosic fibre web has a dry content from about 20 to about 70, for example from about 30 to about 60 or from about 35 to about 55 wt % based on the total weight of the web.
• At least one polymer such as non-ionic, amphoteric, and/or cationic polymers or mixtures thereof can be added to the cellulosic suspension, in particular polymers which are highly charged.
• the polymer can be derived from natural or synthetic sources and can be linear, branched or cross-linked, e.g. in the form of particles.
• the polymer is water-soluble or water-dispersible.
• such at least one polymer can be added in conjunction with a debonder system, for example a debonder composition, in a premix.
• Suitable cationic polymers include cationic polysaccharides, e.g. starches, guar gums, celluloses, chitins, chitosans, glycans, galactans, glucans, xanthan gums, pectins, mannans, dextrins.
• Suitable starches include potato, corn, wheat, tapioca, rice, waxy maize, barley, etc.
• Cationic synthetic organic polymers such as cationic chain-growth polymers may also be used, e.g.
• cationic vinyl addition polymers like acrylate-, acrylamide-, vinylamine-, vinylamide- and allylamine-based polymers, for example homo- and copolymers based on diallyldialkyl ammonium halide, e.g. diallyldimethyl ammonium chloride, as well as (meth)acrylamides and (meth)acrylates.
• Further polymers include cationic step-growth polymers, e.g. cationic polyamidoamines, polyethylene imines, polyamines, e.g. dimethylamine-epichlorhydrin copolymers, and polyurethanes.
• suitable cationic organic polymers include those disclosed in WO 02/12626.
• the polymer is selected from the group of polydiallyldimethyl ammonium chloride, polyamines, cationic starch, amphoteric starch, and polyamidoamine-epichlorohydrin (PAAE), polyethylene imines and polyvinylamines.
• PAAE polyamidoamine-epichlorohydrin
• step-growth polymer refers to a polymer obtained by step-growth polymerization, also being referred to as step-reaction polymer and step-reaction polymerization, respectively.
• chain-growth polymer refers to a polymer obtained by chain-growth polymerization, also being referred to as chain reaction polymer and chain reaction polymerization, respectively.
• the polymer has a molecular weight of from about 10000 to about 10000000, for example from about 15000 to about 5000000, or from about 40000 to about 1000000 g/mol.
• an anionic polymer such as anionic step-growth polymers, chain-growth polymers, polysaccharides, naturally occurring aromatic polymers and modifications thereof is added to the cellulosic suspension.
• the total amount of polymer added ranges from about 0.01 to about 10, such as from about 0.1 to about 5 or from about 0.2 to about 2 kg/ton dry cellulosic fibres.
• an aqueous solution containing the polymer is prepared in which the polymer content is from about 0.1 to about 50, such as from about 0.5 to about 25 wt % which subsequently is added to the cellulosic suspension.
• the aqueous polymer solution is heated up to about 20 to about 70, for example up to about 25 to about 55° C.
• an emulsion of an emollient-surfactant blend and an aqueous solution containing the polymer is prepared with, a static mixer, a high shear device called ultra-turrax or a homogenizer. The emulsion can then be cooled to room temperature. The cooling can be performed for example by means of a heat exchanger.
• an anionic surfactant and/or anionic microparticles such as anionic silica particles, for example anionic colloidal silica particles as defined herein, smectite clays, or mixtures thereof are added to the cellulosic suspension.
• anionic surfactants that can be used according to the invention are for example anionic surfactants with hydrophobic “tails” having from about 6 to about 30 carbon atoms.
• anionic surfactants are saponified fatty acids, alkyl(aryl)sulphonates, sulphate esters, phosphate esters, alkyl(aryl)phosphates, alkyl(aryl) phosphonates, fatty acids, naphthalene sulphonate (NAS), formaldehyde polycondensates, polystyrene sulphonates, hydrophobe-modified NAS, for example saponified fatty acids, alkyl(aryl)sulphonates, sulphate esters, phosphate esters, alkyl(aryl)phosphates, alkyl(aryl) phosphonates, and mixtures thereof.
• the anionic surfactant and/or anionic microparticle is added to the cellulosic suspension in a total amount from about 0.001 to about 1, such as from about 0.005 to about 0.5, or from about 0.01 to about 0.1 kg/ton dry cellulosic fibres.
• non-ionic surfactants that can be used according to the invention include generally ethoxylated or propoxylated fatty acids or fatty alcohols.
• the ethoxylated fatty acids and fatty alcohols can be ethoxylated with from about 1 to about 30 ethylene oxide (EO), or from about 4 to about 25 EO.
• the ethoxylated fatty acids and fatty alcohols may have from about 6 to about 30 carbon atoms, or from about 6 to about 22 carbon atoms.
• the propoxylated fatty acids and fatty alcohols may have been propoxylated with from about 1 to about 30 propylene oxide (PO), or from about 1 to about 8 PO.
• the propoxylated fatty acids and fatty alcohols can have from about 6 to about 30 carbon atoms, such as from about 6 to about 22 carbon atoms. It is also possible to use carbon dioxide instead of propylene oxide.
• a non-ionic surfactant is added in an amount from about 0.1 to about 10, for example from about 0.3 to about 7, or from about 0.5 to about 5 kg/ton dry cellulosic fibres.
• further conventional components may be added to the cellulosic suspension such as wet strength agents, dry strength agents and wetting agents.
• the cellulosic fibres of the cellulosic suspension may include fibres derived from wood pulp, which includes chemical pulp such as sulphite and sulphate pulps, as well as mechanical pulps such as ground wood, thermomechanical pulp and chemical modified thermomechanical pulp. Recycled fibres may also be used.
• the recycled fibres can contain all the above mentioned pulps in addition to fillers, printing inks etc. Chemical pulps, however, are preferred since they impart a superior feeling of softness to tissue sheets made from it.
• the utilization of recycled fibres for making tissue or fluff often includes a process step known as deinking to remove as much as possible of the printing ink from the fibre slurry and most of the filler material to get an acceptable brightness of the recycled fibre slurry and paper machine runnability.
• the deinking process often includes addition of anionic substances such as saponified fatty acids and water glass to the fibre slurry. These substances are sometimes carried over to the paper machine and due to the fact that they are anionic, they can inactivate cationic chemicals added to the stock. These substances are called anionic detrimental substances or “anionic trash”.
• a number of parameters can be measured.
• the static potential is measured.
• the effect of the debonder system can be determined by measuring knot content, burst strength, defiberization energy and wetting rate. Low burst strength and low defiberization energy shows that the fibre-to-fibre bonds are weak, which enhances the softness.
• a coconut oil was mixed with a parasubstituted alkyl benzylsulfonic acid ( ⁇ C12) (anionic surfactant) and an unsaturated fatty alcohol with 16 to 18 carbon atoms being ethoxylated with 5 EO (non-ionic surfactant).
• the contents of the components were 50 wt % oil, 1 wt % anionic surfactant, and 49 wt % non-ionic surfactants.
• the oil-surfactant blend was then heated to 50° C.
• Aqueous solutions with and without a Polyamine Bewoten C410 (polymer) were prepared. The concentration of the polymer in the aqueous solution was 4 wt %. The aqueous solutions were heated separately to 50° C.
• the oil-surfactant blend was subsequently emulsified into the aqueous solutions by means of an Ultra-Turrax® (high-shear equipment).
• the compositions were subsequently cooled to room temperature in a water bath.
• the weight ratio of the oil-surfactant blend to the aqueous solution was 15:85.
• the compositions prepared will in the following be referred to as debonder compositions D1 and D2 respectively.
• silicious materials used in the examples are:
• Dry paper sheets were prepared by mixing 15 grams of chemical pine sulphate pulp with water up to 750 ml. If used, the debonder compositions were added to the pulp suspension followed by 10 minutes of agitation. If used, the silicious materials were added after 8 minutes of agitation. After 10 minutes the formed sheets were prepared in a standard PFI-sheet former (A4 sheets). The sheets were then pressed according to standard method SCAN C26:76. Finally, the sheets were dried on a cylinder to about 90-95% dry content and were then conditioned in a climate room at 23° C. and 50% relative humidity. If the additives were sprayed, 10 ml of the diluted product was used, with a concentration appropriate to receive a certain dosage level. The spraying was either conducted on wet paper web after pressing (about 50% dry content) or on dried and conditioned paper web (about 93% dry content). If sprayed on dried and conditioned paper web, the sheets were dried and conditioned once again before measurements were made.
• the defiberization energy and static potential were measured of sheets prepared from different combinations of debonder compositions added to the cellulosic suspension and silicious materials added to the sheets.
• the amount of debonder composition added to the cellulosic suspension was 2.0 kg/ton based on dry cellulosic fibres.
• the polymer Polyamine Bewoten C410
• the debonder compositions, polymer and silicious materials were added either to the furnish (F) or sprayed on the dried and conditioned paper web (about 93 wt % dry content) (S). Dry paper sheets were prepared according to example 1.
• the static potential of the sheets was measured with an Electrostatic field measurement device (JCI 148) and a high voltage head JCI (John Chubb Instrumentation 140) connected to a pin-defiberizer. The defiberization is measured in kJ/kg and the static potential is measured in kVolt.
• example 3 the static potential of sheets was measured for sole silicious materials. From 0 to 2.0 kg silicious material/ton dry cellulosic fibres were added as set out in table 2. The silicious materials were added either sprayed on the wet paper web (about 50 wt % dry content) (SWP) or the dried and conditioned paper web (about 93 wt % dry content) (SDP). Dry paper sheets were prepared according to example 1. The static potential was measured in the same way as in example 2.
• SWP wet paper web
• SDP dried and conditioned paper web
• example 4 the static potential of sheets was measured for sole silicious materials and combinations thereof. 0 to 0.5 kg silicious material/ton dry cellulosic fibres according to table 3 were added. The silicious materials were sprayed on the wet paper web (about 50 wt % dry content). Dry paper sheets were prepared according to example 1. The static potential was measured in the same way as in example 2.
• the static potential of the sheets was measured, which sheets were prepared from furnishes containing debonder composition, polymer and Laponite without or with silica sol sprayed on the dried and conditioned paper web (about 93 wt % dry content).
• the amount of debonder composition added to the cellulosic suspension was 2.0 kg/ton based on dry cellulosic fibres and polymer addition was 0.033 kg/ton based on dry cellulosic fibres.
• the total amount of silicious material was varied between 0.125 to 2.0 kg silicious material/ton dry cellulosic fibres according to table 4. Dry paper sheets were prepared according to example 1.
• the static potential was measured in the same way as in example 2.
• the static potential and the defiberization energy were measured of sheets prepared by applying a debonder composition and a polymer to the furnish and silica sol (and in some examples polymer P2) sprayed on the dried and conditioned paper web (about 93 wt % dry content).
• the amount of debonder composition added to the cellulosic suspension was 2.0 kg/ton based on dry cellulosic fibres and the polymer addition to the suspension was 0.12 kg/ton based on dry cellulosic fibres.
• the total amount of silicious material was varied between 0.125 to 0.5 kg silicious material/ton dry cellulosic fibres according to table 5.
• P2 polydadmac, Eka ATC 6340
• the addition level of P2 (polydadmac, Eka ATC 6340) to the web was varied between 0.125 to 0.5 kg silicious material/ton dry cellulosic fibres according to table 5.
• Dry paper sheets were prepared according to example 1.
• the static potential and defiberization energy were measured in the same way as in example 2.

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Paper (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Artificial Filaments (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)

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