Abstract: A process of making paper or paper board comprising forming a cellulosic suspension, flocculating the suspension, draining the suspension on a screen to form a sheet and then drying the sheet, characterized in that the suspension is flocculated using a flocculation system comprising a clay and an anionic branched water soluble polymer that has been formed from water soluble ethylenically unsaturated anionic monomer or monomer blend and branching agent and wherein the polymer has
(a) intrinsic viscosity above 1.5 dl/g and/or saline Brookfield viscosity of above about 2.0 mPa.s and
(b) rheological oscillation value of tan delta at 0.005 Hz of above 0.7 and/or
(c) deionised SLV viscosity number which is at least three times the salted SLV viscosity number of the corresponding unbranched polymer made in the absence of branching agent.
Type:
Grant
Filed:
November 2, 2000
Date of Patent:
May 21, 2002
Assignees:
AB CDM Vastra Frolunda, Ciba Specialty Chemicals Watertreatments Ltd.
Inventors:
Bo Hjalmarson, Hans Åsberg, Per-Ola Eriksson, Torbjörn Ljungqvist, Gary Peter Richardson, Gordon Cheng I Chen
Abstract: Paper or paper board is made by adding cationic polymeric retention aid to a cellulosic supension, shearing the suspension to degrade the resultant flocs, aggregating the suspension by adding an aqueous composition of bentonite or other anionic bridging coagulant in the presence of anionic dye, pigment or optical brightening agent, and forming paper from the aggregated suspension.
Type:
Grant
Filed:
November 28, 1997
Date of Patent:
May 16, 2000
Assignees:
Allied Colloids Limited, AB CDM
Inventors:
Per-Ola Eriksson, Ingvar Eriksson, Bo Hjalmarson, John Graham Langley
Abstract: A suspension is dosed with a coagulant and then with a flocculant and is dewatered to form a thickened sludge or cake and separated liquor, and control of the dewatering performance is improved by adding the flocculant at a predetermined dosage, monitoring the charge in the separated liquor (or monitoring other dewatering parameter of the separated liquor or suspension) and adding coagulant at a dosage selected in response to the monitored charge or other parameter value in order to maintain the value substantially at a preselected optimum value.