The present invention provides a novel method and composition for enhancing the efficiency of starch adsorption (i.e., starch trapping) from starch-containing furnishes comprising high content of recycled fibers for use in paper making processes such as pulp, paper, or board production. A novel polymer coagulation system is disclosed in which two quick inversion cationic emulsion polymers (starch trapping polymers A and B) are co-mixed at optimal blend ratios to meet specific recycled fiber and process water requirements for different recycled fiber plants and added to furnishes prior to formation of paper or board in a paper machine. Co-mixed solutions of starch trapping polymers A and B provide synergistic enhancements in (i) starch trapping efficiency and (ii) starch retention in the produced paper or board over equivalent dosage levels of singly administered polymer A, polymer B, or conventional starch trapping products, without over-flocculation or formation of stickies.

The present invention provides a novel method and composition for enhancing the efficiency of starch adsorption (i.e., starch trapping) from starch-containing furnishes comprising high content of recycled fibers for use in paper making processes such as pulp, paper, or board production. A novel polymer coagulation system is disclosed in which two quick inversion cationic emulsion polymers (starch trapping polymers A and B) are co-mixed at optimal blend ratios to meet specific recycled fiber and process water requirements for different recycled fiber plants and added to furnishes prior to formation of paper or board in a paper machine. Co-mixed solutions of starch trapping polymers A and B provide synergistic enhancements in (i) starch trapping efficiency and (ii) starch retention in the produced paper or board over equivalent dosage levels of singly administered polymer A, polymer B, or conventional starch trapping products, without over-flocculation or formation of stickies.

A water-dispersible composite structure, which comprises one or more layers, and a method of producing the same. At least a part of the layers is formed by a fibrous web or sheet containing 50-90 parts by weight of wood fibers and 10-90 parts by weight of annual or perennial plant fibers and/or 10-50 parts by weight of synthetic short-cut fibers, and 0.1-20% by weight of a binder, calculated from the weight of the fibers, and at least a part of the binder being a water-soluble polymer and another part a water dispersible binder, and the fibrous sheet or web being produced by wet forming. By means of the invention, the fibers of the composite structure can be recovered and recycled by equipment conventionally used in the paper and paperboard industry.

A water-dispersible composite structure, which comprises one or more layers, and a method of producing the same. At least a part of the layers is formed by a fibrous web or sheet containing 50-90 parts by weight of wood fibers and 10-90 parts by weight of annual or perennial plant fibers and/or 10-50 parts by weight of synthetic short-cut fibers, and 0.1-20% by weight of a binder, calculated from the weight of the fibers, and at least a part of the binder being a water-soluble polymer and another part a water dispersible binder, and the fibrous sheet or web being produced by wet forming. By means of the invention, the fibers of the composite structure can be recovered and recycled by equipment conventionally used in the paper and paperboard industry.

A method for manufacturing bleached pulp from a feedstock that includes recycled paper. The method includes steps of: (1) impregnating the feedstock with cooking liquor to yield an impregnated material having a liquor-to-fiber mass ratio of at most about 4:1; (2) cooking the impregnated material to remove at least a portion of the lignin within the impregnated material, thereby yielding a cooked pulp; and (3) bleaching the cooked pulp.

A method for manufacturing bleached pulp from a feedstock that includes recycled paper. The method includes steps of: (1) impregnating the feedstock with cooking liquor to yield an impregnated material having a liquor-to-fiber mass ratio of at most about 4:1; (2) cooking the impregnated material to remove at least a portion of the lignin within the impregnated material, thereby yielding a cooked pulp; and (3) bleaching the cooked pulp.

A buffer material of the present disclosure is a buffer material including a buffer sheet that contains cellulose fibers and a binding material binding the cellulose fibers and has a sheet shape, in which the buffer sheet has a plurality of first projections that protrude toward at least one surface side and are provided in a lattice shape. Further, it is preferable that the buffer sheet further have a plurality of second projections having a projection amount that is greater than a projection amount of the first projections.

The present invention aims to provide a technique for easily and rapidly sorting printed materials suitable as raw materials of recycled paper.

Printed materials that are hard to recycle as waste paper can be identified by irradiating the surface of the printed materials with light and measuring the reflected light. Specifically, good quality recycled paper can be made efficiently from printed materials by removing printed materials having an absorption band around 1720 cm.sup.−1, around 1260 cm.sup.−1, around 1160 cm.sup.−1, or around 700 cm.sup.−1 from waste paper raw materials when the printed materials are irradiated with light on their surface.

The present invention aims to provide a technique for easily and rapidly sorting printed materials suitable as raw materials of recycled paper.

Printed materials that are hard to recycle as waste paper can be identified by irradiating the surface of the printed materials with light and measuring the reflected light. Specifically, good quality recycled paper can be made efficiently from printed materials by removing printed materials having an absorption band around 1720 cm.sup.−1, around 1260 cm.sup.−1, around 1160 cm.sup.−1, or around 700 cm.sup.−1 from waste paper raw materials when the printed materials are irradiated with light on their surface.

The current process relates to the treatment of a primary sludge that is produced from waste water treatment facilities such as a pulp mill or a pulp and paper mills. It further relates to a process of using the primary sludge in the production of cellulosic ethanol. It further relates to the use of the treated primary sludge in the manufacture of recycled linerboard.