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
  • D21H17/25—Cellulose
• • 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
  • D21H17/28—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
• • 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
• • 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
  • D21H17/42—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
• • 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
• • 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
  • D21H17/675—Oxides, hydroxides or carbonates
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/71—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes
  • D21H17/74—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes of organic and inorganic material

Definitions

• the invention herein relates to a filler suspension comprising filler particles, an ionic starch and a complementary ionic coadditive. Methods of use of the suspension for the preparation of a paper furnish and the manufacture of a paper from the furnish are also provided.
• filler slurry is conventionally added to a pulp suspension before it is transferred to the forming section of a paper-making machine.
• a retention aid or retention aid system comprising several components is generally added to the pulp/filler suspension to form what is referred to in the paper- making art as the "furnish" to retain the filler in the resulting paper sheet.
• Adding filler to paper can provide numerous improvements in sheet properties, including improved opacity, brightness, feel, and print definition. Further, when the filler is cheaper than the pulp, addition of filler to the sheet results in cost savings. These savings can be substantial when low cost fillers, such as precipitated calcium carbonate (PCC), are used to replace expensive chemical pulp fibers.
• PCC precipitated calcium carbonate
• filled paper can be easier to dry than paper with no filler and, as a result, a paper machine can run faster with less steam consumption, which can further reduce costs and improve productivity.
• the retention aid should provide good filler retention under the high shear and turbulence occurring in the paper manufacturing process and should improve drainage without impairing formation.
• the retention aid chemicals are generally added to the furnish prior to or at the inlet to the headbox of the paper machine.
• the retention aids are typically one, two or three component chemical additives that improve filler and fines retention by a bridging and/or flocculation mechanism. The chemicals help attach the filler particles and fines (small fibrous fragments) to the long fibers or cause their aggregation into larger flocculated particles which are more easily retained in the web.
• the chemicals In order to create the attachment and flocculation, the chemicals must adsorb on the surfaces of the fillers, fines and fibers.
• the degree of adsorption of chemicals and the attachment forces are influenced by many things including furnish cleanliness and furnish chemistry, the properties of the added chemicals, the degree of shear in the papermaking process and the contact time between the retention aids and the furnish components.
• inorganic fillers generally used in paper making such as, without limitation, clay, ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), chalk, talc, titanium dioxide, ground calcium sulphate (GCS) and precipitated calcium sulphate (PCS) are known to impair paper strength and increase demand for chemicals. Fillers with high surface areas have substantial negative effects on strength and increase the chemical demand for additives used for strength, sizing and retention. Due to its shape and narrow particle size distribution PCC has a tendency to reduce bonding in a sheet more than other common papermaking fillers, such as chalk, GCC and clay, and also gives the sheet an open structure which makes the sheet permeable or porous.
• an aspect of this invention is a filler suspension for use in papermaking, comprising filler particles, ionic starch and a complementary ionic coadditive.
• the filler particles are selected from the group consisting of clay, talc, synthetic silicates, sodium magnesium alumino silicate, sodium alumino silicate, ground calcium carbonate (GCC), chalk, precipitated calcium carbonate (PCC), ground calcium sulphate (GCS), precipitated calcium sulphate (PCS), titanium dioxide and combinations thereof.
• the ionic starch is raw starch.
• the ionic starch is swollen ionic starch.
• the ionic starch is cooked ionic starch.
• the ionic starch is cationic.
• the ionic starch is anionic.
• the ionic starch is amphoteric.
• the ionic starch is selected from the group consisting of corn starch, rice starch, potato starch, cassava starch, tapioca starch, waxy corn starch, wheat starch, sorghum starch and waxy sorghum starch.
• the swollen ionic starch is formed by heating an aqueous suspension of raw starch at a gel point temperature of the raw starch ⁇ 10 °C.
• the swollen ionic starch is formed by heating an aqueous suspension of raw starch in a temperature range from the gel point temperature of the starch to the gel point temperature of the starch plus 10 °C.
• the complementary ionic coadditive is an anionic flocculant.
• the anionic flocculants comprise copolymers of acrylamide and sodium acrylate.
• the complementary ionic coadditive is selected from the group consisting of NALCO 61815, Nalco 61816, Nalco 61830, Fennosil® ES210, Fennosil® ES21 1 , Telioform® M305.
• the complementary ionic coadditive is an anionic inorganic microparticle.
• the anionic inorganic particles are selected from the group consisting of bentonites, colloidal silicas, sodium
• the complementary ionic coadditive is nanocellulose.
• the complementary ionic coadditive is polyvinyl alcohol.
• the complementary ionic coadditive is anionic or amphoteric PVAm.
• the complementary coadditive is a biopolymer.
• the biopolymer is starch-based.
• the starch-based biopolymer is N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-methymer
• the complementary ionic coadditive is anionic polyacrylic acid or sodium salt of polyacrylic acid.
• the complementary ionic coadditive is a natural polymer.
• the natural polymer is selected from the group consisting carboxymethylcellulose, natural gums, soy polymers or
• the filler particles are precipitated calcium carbonate.
• An aspect of this invention is a pulp furnish comprising pulp fiber and a filler suspension of this invention.
• the above pulp furnish further comprises an additive selected form the group consisting of a sizing agent, a dry strength agent, a wet strength agent, a retention aid and other functional chemicals such as an optical brightening agent, a dye, a defoamer, a bioside and combinations thereof.
• an additive selected form the group consisting of a sizing agent, a dry strength agent, a wet strength agent, a retention aid and other functional chemicals such as an optical brightening agent, a dye, a defoamer, a bioside and combinations thereof.
• An aspect of this invention is a paper product comprising the above pulp furnish.
• FIG. 1 is a schematic of a paper-making process wherein an ionic starch, a complementary ionic coadditive and filler particles are added to an aqueous medium essentially simultaneously.
• FIG. 2 is a schematic of a paper-making process wherein a
• complementary ionic coadditive is premixed with an ionic starch in an aqueous medium before addition of the filler particles.
• FIG. 3 is a schematic of a paper-making process wherein a
• complementary ionic coadditive is premixed with filler particles in an aqueous medium before addition of an ionic starch starch.
• FIG. 4 is a schematic of a paper-making process wherein an ionic starch is premixed with filler particles in an aquous medium before addition of a complementary ionic coadditive.
• FIG. 5 is a graph of the viscosity response of potato starch when heated to and beyond its gel temperature.
• FIG. 6 comprises microscopic images of potato starch granules as they are heated in water at various temperatures.
• FIG. 7 is a graph showing the tensile strength of a paper sheet made using various filler compositions including those of this invention.
• FIG. 8 is a graph showing the stiffness of a paper sheet made using various filler compositions including those of this invention.
• Table 1 shows a comparison of paper sheet properties in papers made using filler compositions comprising swollen cationic starch and swollen cationic starch plus anionic micorpolymer co-additives.
• Table 2 shows a comparison of paper sheet properties in papers made using filler compositions in which the components of the composition were added in different addition orders.
• Table 3 shows a comparison of the tensile strength improvements of papers made with PCC filler treated with swollen cationic starch only and with PCC filler treated with swollen cationic starch and a co-additive.
• Table 4 shows a comparison of percent paper tensile index/breaking length improvement depending on the addition order of swollen starch and various co-additives to PCC.
• Table 5 shows a comparison of tensile strength improvements over a no-PCC treatment baseline in papers as the result of various PCC treatments.
• Table 6 shows a comparison of paper properties using a filler composition comprising PCC treated with swollen cationic starch or cooked cationic starch or cooked cationic starch with various co-additives.
• a filler suspension for use in papermaking comprising filler particles, an ionic starch and a complementary ionic co-additive in a liquid vehicle, typically water.
• a pulp furnish comprising, in an aqueous vehicle, a filler suspension as set forth herein and pulp fibers.
• the furnish may also contain other papermaking agents.
• a method of producing paper by adding a filler suspension of this invention to a pulp fiber stock to form a pulp furnish, and then manufacturing paper from the furnish.
• Other anionic and cationic agents can be added to the furnish to enhance retention and improve drainage.
• the furnish may also contain other papermaking agents as such are known to those skilled in the art.
• the invention also provides processes for producing starch/coadditive compositions and their combination with filler particles to form a filler suspension.
• the starch herein may be raw, swollen, cooked or combinations thereof.
• raw starch refers to starch that has not been subjected to treatment with hot water or steam sufficient to render it swollen or cooked as these states are described below.
• a "swollen" starch refers to raw starch granules that have absorbed water and have expanded, preferably at present to a state in which no further water can be absorbed without rupturing the swollen granules.
• Exemplary swollen starches suitable for use in a filler suspension herein include, but are not limited to, those disclosed in U.S. Patent Nos. 7,074,845; 7,625,962; and 8,354,004, each of which is incorporated by reference as if set forth in its entirely herein.
• swollen ionic starch 1 , complementary ionic coadditive 8a and filler particles 2 are mixed together in mixer 4 to form a filler suspension which is then transferred to mixer 5, where it is mixed with pulp fiber 3 to form a furnish.
• swollen ionic starch 1 and complementary ionic coadditive 8a are premixed and this combination is subsequently mixed with filler particles 2 in mixer 4 after which the formed filler suspension is mixed with pulp fiber 3 in mixer 5.
• complementary ionic coadditive 8a is premixed with filler particles 2 and that combination is mixed with ionic starch 1 in mixer 4 and the formed filler suspension is transferred to mixer 5 where it is mixed with pulp fiber 3 to form a furnish.
• ionic starch 1 and filler particles 2 are premixed in mixer 4 and the premix is transferred to mixer 5, complementary ionic coadditive 8a being added to the premix essentially in transit between mixer 4 and mixer 5.
• the furnish comprising the filler suspension is subsequently transferred to paper machine 6 along with optional additives 7 to form paper 9.
• retained swollen starch granules will rupture, liberating amylopectin and amylose macromolecules, which operate to bond the solid components of the sheet.
• cooked starch refers to starch that has been heated to a temperature above its gel point and held there until the starch granules have swollen and essentially all the swollen granules have ruptured.
• the combination of ionic starch, ionic coadditive and filler particles can be used for papermaking under acid, neutral or alkaline conditions.
• compositions are used primarily to assure that the filler and starch are well-retained in paper sheets during the paper-making process while having a minimal negative effect on sheet strength.
• ionic starch/ionic coadditive/filler particle ionic starch/ionic coadditive/filler particle
• compositions tends to result in greater strength than using starch or coadditive alone with the filler particles.
• the filler particles can be any known to those of skill in the art and the filler suspension can comprise a single filler or more than one filler.
• the fillers particles are typically inorganic materials having an average particle size ranging from 0.5 to 30 ⁇ , more usually 1 to 10 ⁇ , such as, without limitation, clay, ground calcium carbonate (GCC), chalk, precipitated calcium carbonate (PCC), talc, ground calcium sulphate (GCS) and precipitated calcium sulphate (PCS), titanium dioxide, synthetic silicates, sodium magnesium alumino silicate, sodium alumino silicate and blends thereof.
• the pulp slurry to which the filler suspension is added can be composed of mechanical pulp, chemical pulp, recycled pulp and mixtures thereof.
• Starches suitable for use in this invention include, without limitation, those originating from corn, waxy corn, potato, wheat, tapioca, sorghum, waxy sorghum and rice.
• the starch may be cationic, anionic or amphoteric; each of these forms is well-known in the art and generally commercially available.
• starches can be rendered cationic by inclusion of quarternary ammonium cations in the starch, anionic by include carboxyl or sulfonic groups in the starch and amphoteric by preparing a starch that includes a combination of the foregoing. Since all these ionic starch forms are well-known to those skilled in the paper-making art, they are not further described herein.
• Starch granules are insoluble in cold water. To disperse or “cook” a starch, the starch is heated in aqueous suspension. As heating proceeds, the starch granules first go through a stage of slight, reversible swelling until a critical temperature, referred to as the “pasting,” “gelatinization” or simply “gel” temperature, is reached where massive swelling occurs, which causes a large increase in viscosity. If held for a sufficient period above the gel temperature, the viscosity reverts to lower levels due to the rupture of the swollen granules. Each variety of starch has its own gel temperature.
• the gel temperature for many starches is available in extant literature or it can be readily empirically determined by heating a given starch suspension while monitoring viscosity. Swollen starch granules are distinct from cooked starch. Cooked starch results when swollen starch granules rupture at temperatures above the gel temperature and thereby release amylose and amylopectin, which dissolve in the aqueous medium.
• a particular starch By carefully controlling the treatment of a particular starch, it may be rendered swollen or cooked. With regard to swollen starch, depending on the starch source, the ultimate particle size of the swollen starch granules ranges from about 25 ⁇ to about 100 ⁇ . A representative, but non-limiting, example of a swollen starch preparation is shown in the Examples.
• the coadditive is included in the filler suspension to improve the effect of the ionic starch in enhancing the properties of a filled paper by modification of the filler suspension.
• the coadditive may be cationic, anionic or amphoteric. It is selected so as to have a net charge that is complementary to the net charge on the ionic starch.
• complementary is meant that, if the starch is cationic, it is presently preferred that the coadditive be anionic and vice versa. If the starch is amphoteric, the coadditive may be cationic, anionic or itself amphoteric.
• Anionic coadditives include, without limitation, carboxymethylcellulose, nanocellulose, polyacrylic acid, alginate, colloidal silica, bentonite, polyacrylamide, a natural gum and a soluble soap.
• Cationic coadditives include, without limitation,
• a non-limiting example of an amphoteric coadditive which is suitable as a coadditive for use in a filler suspension of this invention is Ashland-Hercules Hercobond ® 1303.
• anionic colloidal silica nanoparticles such as, without limitation, Eka NP ® 090, Eka NP ® 200, Eka NP ® 320, Eka NP ® 32K, Eka NP ® 442, Eka NP ®
• Eka NP ® 780 Eka NP ® 882, Eka NP ® 890 and EKA NP ® 2180, all from AkzoNobel; Fennosil ® 525 from Kemira, and POSITEK ® 8699 from Nalco.
• Nalco Ultra POSITEK ® 8692, 8693, BD420 and TR420 are sodium borosilicate nanoparticles (typically 1 to 100 nm in size).
• Altonite® from S&B Industrial Minerals, Fennolite ® LF5 from Kemira and Hydrocol ® from BASF are bentonites that are suitable for use as coadditives in a filler suspension of this invention.
• Anionic aluminum hydroxide microparticles are also deemed suitable for use as a coadditive in filler suspensions of this invention.
• Telioform ® M305 a copolymer of sodium acrylate and acrylamide dispersed in mineral oil, as described in an MSDS issued 23 March 2006, from Ciba Specialty Chemicals Corporation (now BASF), is likewise suitable as a coadditive for use in a filer suspension of this invention.
• Other Telioform ® compositions such as, without limitation, Telioform ® M100, M135, M200, M300, S10, M100A, M8A and SC22, may also be suitable for use as a coadditive in a filler suspension of this invention.
• Fennosil ® ES-210 exemplified by Fennosil ® ES-210, Fennosil ® ES-21 1 (both based on
• acrylamide/acrylic acid copolymers and Fennosil ® ES-325; as well as the cationic forms exemplified by Fennosil ® E130 (formulation comprising acrylamide/p-amine), E128 (formulation comprising polyacrylamide/polydimethyldiallylammonium chloride (DADMAC) copolymer), ES-325 (a formulation comprising polyacrylamide/salt) and E-126 (acrylamide/p-amine) are also suitable as coadditives in a filler suspension of this invention.
• Fennosil ® E130 formulation comprising acrylamide/p-amine
• E128 formulation comprising polyacrylamide/polydimethyldiallylammonium chloride (DADMAC) copolymer
• ES-325 a formulation comprising polyacrylamide/salt
• E-126 acrylamide/p-amine
• Nanocellulose such as without limitation described in WO 2007/091942 and WO 2009/126106, both of which are incorporated by reference in their entirety herein, may also be suitable as coadditives for use in a filler suspension of this invention.
• Still other materials presently deemed suitable for use as coadditives in filler suspensions of this invention are cellulose-based materials and derivatives such as Engineeered Cellulose Additive (ECA) from AkzoNobel; noil fibrils as described in U.S. Patent No. 6,156,1 18, which is incorporated by reference as if fully set forth herein; hemicellulose and high hemicellulose-containing materials.
• ECA Engineeered Cellulose Additive
• Carboxymethylcellulose is also suitable as a coadditive in a filler suspension of this invention.
• Natural gums such as guar and xanthan are also suitable coadditives in filler suspensions of this invention.
• NALCO 641 10, 641 14 and, 64170 which are glyoxylated DADMAC/acrylamide copolymer compositions
• NALCO 61815, 61816 and 61830 which are anionic flocculants that are copolymers of acrylamide and sodium acrylate as described generally in.
• U.S. Patent 8,088, 213 which is incorporated by reference as if fully set forth herein.
• Still other materials suitable for use as coadditives in filler suspensions of this invention are Ashland-Hercules Hercobond ® HA5305 and SP7200 and Eka PL8660.
• Polyvinyl alcohol (PVA) is likewise suitable for use as a coadditive in filler suspensions of this invention.
• anionic polyvinylamines PVAm
• amphoteric polyvinylamines such as,without limitation, the amphoteric terpolymer of vinylformamide, vinylamine and acrylic acid, a non-limiting example of which is XELOREX ® F3000 from BASF.
• Biopolymers may also be used as coadditives in filler suspensions of this invention.
• Suitable biopolymers for use as filler additives include, without limitation, starch-based biopolymers.
• the biopolymer may be micro- or nano- particulate.
• Biopolymers include, without limitation, EcoSphere 2202 binder from Ecosynthetix of Burlington, Ontario, Canada.
• the coadditive is a polymer, it may be not cross-linked, lightly cross- linked or heavily cross-linked.
• the coadditive may be water-soluble or water-insoluble.
• a non-limiting example of a water-soluble coadditive is Telioform ® M303, a polyacrylamide-based anionic polymer.
• a polymeric coadditive may be a micropolymer.
• a "micropolymer” refers to the polymeric particles obtained by emulsion polymerization, dispersion polymerization and water-in-water polymerization wherein the reaction of water-soluble monomers is carried out in the presence of coagulants such as, without limitation, polyamines such as DADMAC or DIMAPA.
• the micropolymer may be "structured," that is, the individual polymer strands within the polymeric particles may adopt a stable three-dimensional structure.
• lightly cross-linked is meant that the cross-linked polymer remains substantially water soluble. That is, a lightly cross-linked polymer appears more like a “branched” polymer than a fully cross-linked polymer in which the polymer chains are inextricably intertwined and is thereby rendered insoluble in water.
• lightly cross-linked and branched are used interchangeably to refer to a polymer that is cross-linked but is still water-soluble. Examples of anionic, branched, water-soluble polymers are described in U.S. Patent Nos. 5,958,188, 6,391 ,156 B1 , 6,395,134 B1 , 6,406,593 B1 and 6,454,902 B1 , which are hereby incorporated by reference in their entireties as if fully set forth herein.
• Heavily cross-linked simply refers to a polymer that, while soluble when not cross-linked or lightly crosss-l inked, is no longer water soluble as the result of the degree of cross-linking.
• the suspension will comprise 60 to 99.5% by weight filler, 35 to 0.499 % by weight ionic starch and 5.0 to 0.001 % by weight complementary ionic coadditive to a total of 100% based on the total solids content of filler particles, ionic starch and complementary ionic coadditive.
• the suspension will contain complexes of ionic starch and complementary ionic coadditive but may also contain free ionic starch and free ionic coadditive.
• compositions, suspensions and furnishes herein may additionally include conventional papermaking agents such as, without limitation, sizing agents such as alkylketene dimer, alkenyl succinic anhydride and rosin; wet and dry strength agents, and cationic or anionic polymeric retention aids.
• the composition may include a retention aid which may be a single chemical, such as an anionic micro-particle (colloidal silicic acid, bentonite), anionic polyacrylamide, a cationic polymer (cationic polyacrylamide, cationic starch), dual chemical systems (cationic polymer/anionic micro-particle, cationic polymer/anionic polymer) or three
• cationic polymer/anionic microparticle/an ionic polymer cationic polymer/anionic micro-polymer/an ionic polymer.
• retention aid chemicals cationic polymer/anionic microparticle/an ionic polymer, cationic polymer/anionic micro-polymer/an ionic polymer.
• the filler suspension herein is used in an amount of 5% to 70%, as dry solids, based on the dry weight of pulp in the furnish.
• Paper sheets made with filler suspension according to this invention can exhibit greater internal bond strength, as measured by the Scott bond technique, than a control sheet made with no filler treatment.
• the wet and dry strength properties of sheets made using the filler suspension herein can be greater than those sheets made with the filler alone.
• a filler suspension of this invention permits the production of filled papers, such as coated and uncoated fine papers, super-calendered papers, and newsprint, with minimal strength loss and good optical properties.
• Using the filler suspension of this invention can thus allow papermakers to produce filled papers with higher filler content in the paper sheet.
• the potential benefits from the use of the treated filler suspensions of the present invention include improved sizing, wet strength, dry strength and printability, and/or reduced use of expensive reinforcement chemical pulp fiber.
• the combination of ionic starch and ionic coadditive may be used to strengthen paper grades that contain no filler such as sack papers and paperboard products.
• the starch to be used is raw, it can be suspended in water or it may be suspended in water and heated to a temperature that is sufficiently below its gel point so as to neither swell the starch to a significant extent nor cook it.
• a swollen starch is desired, raw starch, in an aqueous slurry at typically 0.5-20% solids at room temperature may be swollen at temperatures approximately the starch gel point in a batch cooker, a jet cooker or by mixing with hot water.
• the preferred method is to swell the granules by mixing the starch slurry prepared in cold water with hot water.
• the temperature of hot water used depends on the consistency of the initial starch slurry in cold water, the final target temperature of the swollen starch, the temperature of the cold starch slurry, pH, and residence time.
• the temperature and reaction time for preparing the swollen starch depends on the type of starch used, the pH of the starch slurry and heating time. The following are examples of processes for the preparation of swollen starch for the purposes of this invention.
• a raw ionic starch dispersion in cold water is swelled by heating it to a temperature that is approximately the gel point of the particular starch.
• complementary coadditive is added and the mixture is added to an agitated filler suspension.
• a starch dispersion is first swelled, then added to an agitated filler suspension followed by the introduction of coadditive.
• the starch powder is dispersed in cold water then mixed with hot water or heated to a temperature that is approximately the starch gel point.
• the swollen starch is then rapidly mixed with the filler suspension at a temperature below the starch gel point followed by addition of coadditive.
• a starch dispersion is first swelled and then added to an agitated coadditive/filler suspension.
• the starch powder is dispersed in cold water and then mixed with hot water or heated to a temperature of approximately the gel temperature of the particular starch. The swollen starch is then rapidly mixed with the filler suspension.
• the treated filler suspensions can be introduced directly into the pulp slurry or, if desired, can be diluted and added to the paper machine pulp stock prior to the sheet forming process, e.g., at the blend chest, the machine chest, or at the inlet of the fan pump.
• the treated-filler suspensions tend to retain their flocculation characteristics over time when added to papermaking pulp slurries.
• retention aids such as anionic micro-particles (colloidal silica, bentonite, organic micropolymers), anionic polymers (anionic polyacrylamide), cationic polymers (cationic polyacrylamide, cationic starch) can be increased.
• a 0.3 % concentration stock was prepared by mixing internal cationic starch with pulp furnish followed by pretreated PCC and finally retention aid.
• 80 g/m 2 wood-free handsheets were made using a dynamic sheet former (DSF) followed by dynamic sheet pressing and drying at 120 °C. Prior to paper testing the paper sheets were colandered under the same conditions and then conditioned at 50% relative humiditry (RH) and 22 °C.
• Fiber 100 % eucalyptus used as pulp, refined to SR 30 (at 20 °C) using a Valley Beater lab refiner.
• Filler precipitated calcium carbonate (ALBACAR ® LO PCC) from Specialty Minerals Inc., average particle size 2.3 ⁇ .
• the PCC content in the sheets varied between 19.3 % and 25.9 % by weight.
• Swollen cationic starch used for PCC pretreatment Cationic potato starch. Swollen cationic starch was prepared by mixing dry cationic starch powder with water to make 3 % solids slurry, which was then heated to 63 °C under mixing. Swollen cationic starch was used for PCC pretreatment by mixing 5 kg swollen cationic starch per metric ton (tonne, tn) of paper with PCC at 20 % solids. Some filler samples were only pretreated with swollen cationic starch and some were pretreated with swollen starch and anionic coadditive.
• Internal starch Cationic potato starch. Dry starch powder was mixed with water to a 1 % solids slurry, which was then cooked at 97 °C with mixing.
• Cooked cationic starch was used at 8 kg/paper tonne by mixing it with pulp furnish. Retention aid: 0.2 kg/paper tonne of cationic polyacrylamide (CPAM) was used for retention.
• CPAM cationic polyacrylamide
• Table 1 presents the properties of the sheets made with only swollen starch treated PCC and swollen starch followed by anionic micropolymer treated PCC.
• Anionic micropolymer doses were 0.05 - 0.1 % as received material/dry PCC weight.
• the sheets having anionic micropolymer in PCC pretreatment show better strength properties - tensile, internal bond, bending stiffness - compared to swollen starch alone treated PCC. The best strength performance was achieved with 0.1 % anionic micropolymer dose. This would allow a 6% unit filler increase without loss in strength properties.
• PCC precipitated calcium carbonate
• SST cationic swollen starch
• AMP anionic micropolymer
• Tensile and stiffness values are geometrical averages from machine and cross directions.
• Table 2 presents the properties of paper sheets made with only swollen starch treated PCC, and swollen starch and anionic micropolymer treated PCC using different addition orders: PCC treated with swollen starch followed by anionic micropolymer and anionic micropolymer treated PCC followed by swollen starch.
• anionic micropolynner improves the strength properties of the sheets made with swollen starch treated PCC independent of the addition order.
• PCC precipitated calcium carbonate
• SST cationic swollen starch
• AMP anionic micropolymer
• Tensile values are geometrical averages from machine and cross directions.
• the microscope images in Figure 6 illustrate how starch granules swell and how the viscosity increases until it starts to decrease due to rupture of swollen starch granules.
• the images represent samples of potato starch at 25 °C, 56 °C, 60 °C, 66 °C and 95 °C.
• swollen starch refers to the condition at which most of the granules have started to swell as shown in the 56 °C image up to to the point where large swollen granules are still visible as seen in the 66 °C image.
• the viscosity curve can be used to determine when a starch is sufficiently swollen for use in preparing the filler suspension of this invention.
• the maximum viscosity area in FIG. 5 is where most of the starch granules are swollen but not ruptured.
• the temperature range within which useful swollen starch granules can be obtained is in a range that extends from the peak region of FIG.
• the temperature at which the raw starch suspension is heated to create a swollen starch is between the peak temperature and the peak temperature of Fig. 5 plus 10 °C, where all the starch granules are swollen and all unswollen granules eliminated.
• the raw materials used in the sheet making were following:
• Fiber 100 % eucalyptus used as pulp, refined to SR 30 (at 20 °C) using a Valley Beater lab refiner.
• ABACAR ® LO PCC precipitated calcium carbonate
• Specialty Minerals Inc. average particle size of 2.1 ⁇ .
• the PCC content in the sheets varied between 20.4 % and 25.5 % by weight.
• the PCC is used 1 ) without any pretreatment, 2) pretreated using only swollen starch and 3) pretreated with anionic micropolymer and raw starch.
• Starch used for PCC pretreatment Cationic corn starch, which was used in two ways:
• [0125] 1 Prepared by mixing dry cationic starch powder with water to make 3% solids slurry and used as such with co-additive, the starch being in granule form.
• anionic polymer (Telioform ® M305, trade-mark from BASF, marketed as a
• micropolymer The treatment of PCC was done by first mixing the Telioform ® with the PCC followed by addition of cold raw starch slurry.
• the Telioform ® M305 dose was 0.04 kg/tn paper.
• the raw cationic starch dose was 5 kg/tn paper.
• Internal starch Cationic corn starch. Dry starch powder was mixed with water to arrive at a 1 % solids slurry, which was then cooked at 97 °C under mixing. Cooked cationic starch was used 8 kg/tn paper as internal starch by mixing it with pulp furnish.
• Retention aid Additionally 0.15 kg/paper tn cationic polyacrylamide (CPAM) and 1 .5 kg/paper tn silica were used for retention.
• CPAM cationic polyacrylamide
• 1 .5 kg/paper tn silica were used for retention.
• PCC pretreatment with swollen starch improves paper strength compared to papers made without such pretreatment.
• Further improvement can be achieved by enhancing the interaction between cationic starch and cationic PCC using anionic micropolymer.
• the cationic starch can even be raw as shown in the example. Similar behaviour can be seen in stiffness in FIG 8.
• a 0.3% concentration stock was prepared by mixing internal cationic starch with pulp furnish followed by pretreated PCC (or in case of baseline standard PCC without any pretreatment). Before forming paper sheets, a retention aid was added to the stock. The 80 g/m 2 wood-free handsheets were made using a dynamic sheet former (DSF) followed by dynamic sheet pressing and then drying at 120 °C. Prior to paper testing the paper sheets were calendered under the same conditions and then conditioned at 50% RH and 22 °C.
• DSF dynamic sheet former
• Fiber 100 % eucalyptus used as pulp, refined to SR 30 (at 20 °C) using a Valley Beater lab refiner.
• Filler precipitated calcium carbonate (ALBACAR® LO PCC) from Specialty Minerals Inc., average particle size of 2,3 ⁇ . Filler amount in the sheets were adjusted to two levels, 20 % and 25 % by weight.
• Swollen starch used for PCC pretreatment Cationic corn starch.
• Swollen starch was prepared by mixing dry cationic starch powder with water to make 3 % solids slurry, which was then heated up to 75 °C under mixing. Cationic swollen starch was used for PCC pretreatment by mixing 5 kg/paper tn of swollen starch with PCC at 20 % solids. Some filler samples were only pretreated with swollen starch and some were pretreated with swollen starch and co-additive.
• Co-additives used for PCC pretreatment with swollen starch The treatment of PCC was done by mixing swollen starch and co-additive with PCC. Different addition orders and co-additive amounts were used. Swollen starch amount was kept fixed 5 kg/tn of paper. Mixing time for each component was 1 min. Tested co-additives were: carboxymethylcellulose (CMC), polyacrylic acid, soy polymer and nanocellulose.
• Internal starch Cationic corn starch. Dry starch powder was mixed with water to get a 1 % solids slurry, which was then cooked at 97 °C under mixing.
• Cooked cationic starch was used 8 kg/paper tn as internal starch by mixing it to pulp furnish. [0139] Retention aid: Additionally 0,2 kg/paper tn cationic polyacrylamide (CPAM) was used for retention.
• CPAM cationic polyacrylamide
• Table 3 presents the tensile strength improvement achieved with PCC filler pretreatment compared to baseline condition without any PCC treatment.
• PCC filler was either pretreated with swollen starch alone, or with swollen starch and additional co-additive. Tensile strength comparison is done at equal ash level.
• PCC precipitated calcium carbonate
• SST cationic swollen starch
• Tensile index values are geometrical averages from machine and cross directions.
• a 0.5 % concentration stock was prepared by mixing internal cationic starch with pulp furnish followed by pretreated PCC (or in case of baseline standard PCC without any pretreatment). Before forming paper, a retention aid was added to the stock. The 80 g/m 2 wood-free handsheets were made using a Formax sheet former, followed by dynamic sheet pressing and then drying at 120 °C. Prior to paper testing the paper sheets were conditioned at 50% RH and 23 °C and calendered from both sides first at 180 psi and then both sides at 220 psi.
• Fiber 100 % eucalyptus used as pulp, refined to SR 30 (at 20 °C) using Valley Beater lab refiner.
• Filler precipitated calcium carbonate (ALBACAR® LO PCC) from Specialty Minerals Inc., average particle size of 2,3 ⁇ . Filler amount in the sheets were adjusted to two levels, 20 % and 25 % by weight.
• Swollen starch used for PCC pretreatment Cationic corn starch.
• Swollen starch was prepared by mixing dry cationic starch powder with water to make a 1 % solids slurry, which was then heated up to 75 °C under light mixing in a starch cooker. Cationic swollen starch was used for PCC pretreatment by mixing 5 kg/paper tn of swollen starch with PCC at 20 % solids. Some filler samples were only pretreated with swollen starch and some were pretreated with swollen starch and co- additive.
• Co-additive used for PCC pretreatment with swollen starch The treatment of PCC was done by mixing swollen starch and co-additive with PCC at temperature 55 °C. Different addition orders and co-additive amounts were used. Mixing time for each component was 1 min. After all components were mixed with PCC, the blend was heated up to 70 °C under constant low shear mixing.
• tested co-additives anionic aluminium hydroxide, natural gum, silica, bentonite, polyvinyl alcohol (PVA), PVAm, biopolymer and several anionic polymers.
• PVA polyvinyl alcohol
• PVAm polyvinyl alcohol
• Internal starch cationic corn starch. Dry starch powder was mixed with water to get a 0,5 % solids slurry, which was then cooked at 95 °C under low mixing in a starch cooker. Cooked cationic starch was used at 8 kg/paper tn as internal starch by mixing it to pulp furnish. In one of the examples, cooked cationic starch was used at 5 kg/tn for PCC pretreatment instead of swollen starch. Cooked starch treatment was done with and without co-additive.
• Retention aid Additionally 0,2 kg/paper tn cationic polyacrylamide (CPAM) was used for retention.
• CPAM cationic polyacrylamide
• Example 10 The method of Example 10 was followed. [0153] Different addition orders for PCC, swollen starch and co-additive have been tested in lab scale. PCC treatment was done by either first mixing swollen starch with PCC followed by co-additive or by first mixing co-additive with PCC followed by swollen starch.
• PCC precipitated calcium carbonate
• SST cationic swollen starch
• Table 5 presents the tensile strength improvements achieved with PCC filler pretreatment compared to baseline condition without any PCC treatment.
• PCC filler was either pretreated with swollen starch alone, or with swollen starch and additional co-additive. Comparison is done at equal ash level.
• Natural gum Kelzan 1 (calc. as dry) co-additi ⁇ e + sst 13
• PCC precipitated calcium carbonate
• SST cationic swollen starch
• PCC pretreatment can be also done with the cooked starch instead of swollen starch, but the strength performance with cooked starch is significantly lower than that using swollen starch.
• Table 6 shows the results where PCC has been treated with swollen starch alone and with cooked starch alone. In both cases 5kg/tn starch was used. While swollen starch treatment gave 13% improvement in tensile strength, cooked starch gave 3% at equal ash level.
• the cooked starch filler treatment can also be improved by using co-additive as shown in Table 6. Depending on dosage the performance can be doubled compared to cooked starch treatment alone. TABLE 6
• PCC precipitated calcium carbonate

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