Abstract: To produce a calcium carbonate in a controlled form while carbon dioxide gas is efficiently used. A method for producing a calcium carbonate comprises a carbon dioxide gas absorption step of allowing an aqueous sodium hydroxide solution at a concentration of 5 to 21% to absorb carbon dioxide gas to give an aqueous sodium carbonate solution at a concentration of 4 to 24%; a hydration step of reacting calcium oxide with an aqueous sodium hydroxide solution at a concentration of 0 to less than 6% to give a lime milk that is a suspension of calcium hydroxide having a BET specific surface area of 5 to 40 m2/g; and a carbonation step of adding the aqueous sodium carbonate solution to the lime milk and performing reaction.

Abstract: A method of manufacturing a newsprint paper for offset printing, includes: selecting a filler or fillers having an average grain size of 0.5 to 5 ?m and a zeta potential of 0 mV or above; providing a pulp slurry for making a base paper; adding the filler or fillers to the pulp slurry in an amount of more than 15 percent by weight but less than 40 percent by weight as ash relative to the dry weight of the base paper; and subjecting the resultant slurry to a papermaking machine to obtain the base paper.

Abstract: A method of manufacturing a newsprint paper for offset printing, includes: selecting a filler or fillers having an average grain size of 0.5 to 5 ?m and a zeta potential of 0 mV or above; providing a pulp slurry for making a base paper; adding the filler or fillers to the pulp slurry in an amount of more than 15 percent by weight but less than 40 percent by weight as ash relative to the dry weight of the base paper; and subjecting the resultant slurry to a papermaking machine to obtain the base paper.

Abstract: A printability improving agent for use in a neutral newsprint base paper which is printed with ecological inks, containing (I) a cationic copolymer obtained by polymerizing one or more hydrophobic monomer unit(s) selected from styrenes and alkyl acrylates and/or alkyl methacrylates with a quaternary ammonium salt-containing monomer unit, and (II) a copolymer obtained by polymerizing 100 parts by weight of one or more hydrophobic monomer(s) selected from the group above in the presence of 1-10 parts by weight of a surfactant.

Abstract: A method of manufacturing a newsprint paper for offset printing, includes: selecting a filler or fillers having an average grain size of 0.5 to 5 ?m and a zeta potential of 0 mV or above; providing a pulp slurry for making a base paper; adding the filler or fillers to the pulp slurry in an amount of more than 15 percent by weight but less than 40 percent by weight as ash relative to the dry weight of the base paper; and subjecting the resultant slurry to a papermaking machine to obtain the base paper.

Abstract: Newsprint for offset printing having sufficient water absorption resistance to provide a clear printing image with less color registration problems upon offset printing is manufactured by coating base paper, to which aluminum sulfate (a 50% by weight Al2O3.14H2O product) is added at a ratio of less than 3.0% by weight upon paper making, with a surface treating agent mainly comprised of (A) a water-soluble macromolecular substance selected from starches, PVAs, polyacrylamides, and cellulose derivatives, (B) a copolymer obtained by the copolymerization of a styrene monomer and a cationic monomer, a water-soluble copolymer obtained by the copolymerization of a styrene monomer, a cat ionic monomer and a hydrophobic monomer, or a water-soluble copolymer obtained by treating one of these copolymers in which a tertiary amine-containing vinyl monomer is used as a cationic monomer, with a quaternizing agent.

Abstract: Coat a starch-based surface-paper-strengthening agent on a base paper made from a paper material that contains at least chemically processed hardwood mechanical pulp and bulk-increasing agent; where it is desirable that the hardwood mechanical pulp with a single fiber density index of 0.20 or more be blended by 10 to 60 weight-% of the total weight of pulp, with the adding amount of bulk-increasing agent adjusted to 0.1 to 1.2 weight-% and the coating amount of starch-based surface-paper-strengthening agent, to 0.3 to 3.0 g/m2.

Abstract: The present invention aims to provide printability improving agents and surface-treating agents capable of improving offset printability of papers, especially newsprint papers to be printed with offset inks as well as papers, especially newsprint papers that can be successfully printed with offset inks. According to a first aspect of the present invention, a printability improving agent comprising a cationic copolymer consisting of one or more hydrophobic monomer unit(s) selected from a specific group and a quaternary ammonium salt-containing monomer unit or a surface-treating agent comprising the printability improving agent and a water-soluble polymer material selected from a specific group is applied on the surface of a base paper, especially a newsprint base paper.

Abstract: The object of the present invention provides a newsprint paper having a friction coefficient in an appropriate range, a sufficient sizing quality, a low “neppari” strength and excellent printability. A newsprint paper having a static friction coefficient in an appropriate range of 0.44-0.74, a sufficient sizing quality and a low “neppari” strength can be obtained by applying a coating solution containing an alkenyl ketene dimer represented by general formula 1 below and a paper surface-modifying agent on a newsprint base paper, especially a neutralized newsprint base paper containing 1% by weight or more and 30% by weight or less of calcium carbonate as a filler and 50% by weight or more of deinked pulp. wherein R1 and R2 represent an unsaturated hydrocarbon group containing 8-30 carbon atoms.

Abstract: Inexpensive spindle- or rice-like calcium carbonate giving useful properties for brightness, opacity and wire abrasion resistance as a paper filler is provided by taking advantage of the causticization step. When a white liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 10% by weight or less and is slaked with the white liquor at a concentration of 20 to 60% to prepare a milk of lime. When a green liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 0.1 to 10% by weight and is slaked with the green liquor at a concentration of 20 to 60% to prepare a milk of lime. In a second step, causticization reaction takes place at a green liquor loading rate of 0.02 to 0.5 cc (green liquor)/min/g (quick lime) at a reaction temperature of 20 to 105° C. to afford spindle- or rice-like calcium carbonate.

Abstract: Provide a newsprint paper for offset printing that offers good printing efficiency and print quality, wherein the paper, despite a high content of deinked pulp, notably suppresses show-through in offset printing and also reduces paper powder deposit on the blanket cylinders of the press. Adding a filler or fillers by more than 15 percent by weight but less than 40 percent by weight as ash relative to the paper weight notably suppresses show-through of a newsprint paper for offset printing. In particular, adding calcium carbonate with an average grain size of 0.5 to 5 ?m and zeta potential of 0 mV or above by more than 15 percent by weight but less than 40 percent by weight as ash relative to the paper weight not only suppresses show-through further but also reduces the paper powder deposit on the blanket cylinders of the press.

Abstract: Newsprint for offset printing having sufficient water absorption resistance to provide a clear printing image with less color registration problems upon offset printing is manufactured by coating base paper, to which aluminum sulfate (a 50% by weight Al2O3.14H2O product) is added at a ratio of less than 3.0% by weight upon paper making, with a surface treating agent mainly comprised of (A) a water-soluble macromolecular substance selected from starches, PVAs, polyacrylamides, and cellulose derivatives, (B) a copolymer obtained by the copolymerization of a styrene monomer and a cationic monomer, a water-soluble copolymer obtained by the copolymerization of a styrene monomer, a cationic monomer and a hydrophobic monomer, or a water-soluble copolymer obtained by treating one of these copolymers in which a tertiary amine-containing vinyl monomer is used as a cationic monomer, with a quaternizing agent.

Abstract: Calcium carbonate in the form of aragonite crystals suitable for use as a filler for papermaking to give useful properties for bulk, whiteness, opacity, wire abrasion and yield is obtained by taking advantage of the causticization step. Herein disclosed is a process for producing calcium carbonate in the form of aragonite crystals which is useful as a filler for papermaking via the causticization step of the sulfate or soda pulping process, comprising adding an aqueous alkaline solution having a hydroxide ion level of 3 mol/l or less and containing 0.25 mol or less of carbonate ion per 1 mol of quick lime to quick lime and/or slaked lime at a quick lime concentration of 1–60% by weight with stirring to prepare milk of lime, and then adding green liquor to said milk of liquor at a loading rate of 0.002–0.12 g (sodium carbonate)/min/g (quick lime) to perform a causticization reaction at a temperature of 30–105° C.

Abstract: A lignocellulose material is cooked by means of an alkaline cooking liquor containing polysulfides in the presence of a quinone-hydroquinone compound, of which the oxidation-reduction potential in the form present during the cooking, which potential is a value calculated as a standard oxidation-reduction potential (Ea) with a hydrogen ion activity of 1, is within a range of from 0.12 to 0.25V to the standard hydrogen electrode potential. It is thereby possible to cook the lignocellulose material with a low Kappa number and in good yield and at the same time, to reduce the amount of the chemical solution used and to reduce the load on a recovery boiler.

Abstract: Provide a bulky paper that provides improved paper-strength properties such as higher tensile strength without increasing paper density, while also offering good optical characteristics such as opacity and brightness, wherein the paper is produced by: (a) blending polyacrylamides that have an electric charge of 2.0 m-equivalent/g or less at pH2 and also 2.0 m-equivalent/g or less at pH12; (b) adding fillers comprising amorphous silica or silicate with a specific bulk density of 0.3 g/ml or less, bulk-increasing agents comprising fatty-acid polyamide compound or of ester compound of polyhydric alcohol and fatty acid, and/or mercerized pulps or bridged pulps; and (c) adjusting the relative bonding area of the paper containing polyacrylamides to 1.2 times the relative bonding area of a paper not containing polyacrylamides, or less.

Abstract: Coat a starch-based surface-paper-strengthening agent on a base paper made from a paper material that contains at least chemically processed hardwood mechanical pulp and bulk-increasing agent; where it is desirable that the hardwood mechanical pulp with a single fiber density index of 0.20 or more be blended by 10 to 60 weight-% of the total weight of pulp, with the adding amount of bulk-increasing agent adjusted to 0.1 to 1.2 weight-% and the coating amount of starch-based surface-paper-strengthening agent, to 0.3 to 3.0 g/m2.

Abstract: Inexpensive spindle- or rice-like calcium carbonate giving useful properties for brightness, opacity and wire abrasion resistance as a paper filler is provided by taking advantage of the causticization step. When a white liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 10% by weight or less and is slaked with the white liquor at a concentration of 20 to 60% to prepare a milk of lime. When a green liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 0.1 to 10% by weight and is slaked with the green liquor at a concentration of 20 to 60% to prepare a milk of lime. In a second step, causticization reaction takes place at a green liquor loading rate of 0.02 to 0.5 cc (green liquor)/min/g (quick lime) at a reaction temperature of 20 to 105° C. to afford spindle- or rice-like calcium carbonate.

Abstract: An object of the present invention is to provide a newsprint paper having a friction coefficient in an appropriate range, a sufficient sizing quality, a low “neppari” strength and excellent printability.

Abstract: Produce a printing paper that offers sufficient bulk and flexibility by using a bulk-increasing/softening agent with a HLB of 6 or below, which is either a liquid or a solid with a melting point of 40° C. or below, wherein the agent may be an ester compound of polyhydric alcohol and higher fatty acid or a long-chain alkyl ammonium salt, and by adjusting the surface temperature of the paper during a preheating drying period (a period during a drying process before the temperature of a wet paper becomes constant) to at least 10° C. higher than the melting point of the bulk-increasing/softening agent.

Abstract: Inexpensive spindle- or rice-like calcium carbonate giving useful properties for brightness, opacity and wire abrasion resistance as a paper filler is provided by taking advantage of the causticization step. When a white liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 10% by weight or less and is slaked with the white liquor at a concentration of 20 to 60% to prepare a milk of lime. When a green liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 0.1 to 10% by weight and is slaked with the green liquor at a concentration of 20 to 60% to prepare a milk of lime. In a second step, causticization reaction takes place at a green liquor loading rate of 0.02 to 0.5 cc (green liquor)/min/g (quick lime) at a reaction temperature of 20 to 105° C. to afford spindle- or rice-like calcium carbonate.