# US 7,407,561 B2 · Use of water-soluble crosslinked cationic polymers for controlling deposition of pitch and stickies in papermaking > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,407,561 B2 - Document ID: US7407561B2 - Status: Granted - Kind: B2 - Application number: 10/827,790 - Filed: 2004-04-20 - Published: 2004-11-18 - Granted: 2008-08-05 - Earliest claimed: 2003-05-13 - Assignees: Ciba Specialty Chemicals Water Treatments Ltd. - Inventors: Zhiqiang Song; Philip Anson Ford - Web page: https://patentgrep.com/patent/US7407561B2 ## CPC - D21H 21/02: Agents for preventing deposition on the paper mill equipment, e.g. pitch or slime control (removal of fats, resins, pitch, or waxes D21C9/08) - D21H 17/54: obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen - 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 ## Abstract The present invention relates to a method for controlling pitch and stickies deposit in a pulp and papermaking process using crosslinked cationic polymers made by controlled addition of a water soluble radical initiator at reaction temperature with agitation for chain extension and crosslinking. ## Claims ### Claim 1 A method of controlling pitch and stickies deposition in papermaking, which method comprises the step of adding to paper furnish prior to sheet formation a multi-crosslinked cationic polymer, which polymer is prepared by the method comprising: (i) polymerizing substantially all of the monomer components by free radical initiation to form a base cationic polymer solution, wherein at least one of the monomer components is a cationic monomer component; and (ii) contacting the base cationic polymer solution with additional free radical initiator to form interconnecting bonds between the base cationic polymers to form the multi-crosslinked cationic polymer and the interconnecting bonds occur at points on the backbone of the cationic polymer, wherein the multi-crosslinked cationic polymer has a higher molecular weight than the base cationic polymer, which base cationic polymer is a homopolymer formed from diallydialkylammonium monomer. ### Claim 2 (depends on 1) A method according to claim 1 wherein the additional free radical initiator used in step (ii) is selected from the group consisting of potassium persulfate, sodium persulfate, ammonium persulfate, salts of percarbonic acid, salts of perphosphonic acid and mixtures thereof. ### Claim 3 (depends on 1) A method according to claim 1 wherein the additional free radical initiator used in step (ii) consists of an effective amount of ammonium persulfate. ### Claim 4 (depends on 1) A method according to claim 1 wherein the additional free radical initiator is added in incremental amounts over a defined period of time. ### Claim 5 (depends on 1) A method according to claim 1 wherein the base cationic polymer solution is diluted to a solids content of less than 30% by weight based on the total solution prior to start of step (ii). ### Claim 6 (depends on 4) A method according to claim 4 wherein the base cationic polymer solution is diluted to a solids content of less than 30% by weight based on the total solution prior to start of step (ii). ### Claim 7 (depends on 1) A method according to claim 1 wherein the multi-crosslinked cationic polymer formed in step (ii) has a weight average molecular weight greater than 700,000 g/mole. ### Claim 8 (depends on 7) A method according to claim 7 wherein the multi-crosslinked cationic polymer formed in step (ii) has a weight average molecular weight greater than 850,000 g/mole. ### Claim 9 (depends on 1) A method according to claim 1 wherein the multi-crosslinked cationic polymer formed in step (ii) has a Brookfield viscosity when measured at 25° C. and 20% solids concentration in water of above 2000 cps using a number 3 or 4 spindle at 12 revolutions per minute, wherein the solids concentration is based on the total weight of the solution. ### Claim 10 (depends on 9) A method according to claim 9 wherein the multi-crosslinked cationic polymer formed in step (ii) has a Brookfield viscosity when measured at 25° C. and 20% solids concentration in water of about 2000 to about 10,000 cps using a number 3 spindle , wherein the solids concentration is based on the total weight of the solution. ### Claim 11 (depends on 9) A method according to claim 9 wherein the multi-crosslinked cationic polymer has a Brookfield viscosity when measured at 25° C. and 20% solids concentration in water of about 10,000 to about 20,000 cps using a number 4 spindle, wherein the solids concentration is based on the total weight of the solution. ### Claim 12 (depends on 1) A method according to claim 1 wherein the diallyldialkyl ammonium monomer is represented by the formula: where R1 and R2 are independently of one another hydrogen or C1-C4 alkyl; R3 and R4 are, independently of one another, hydrogen or an alkyl, hydroxyalkyl, carboxyalkyl, carboxyamidoalkyl, alkoxyalkyl group having from 1 to 18 carbon atoms; and Y− represents an anion. ### Claim 13 (depends on 12) A method according to claim 12 wherein the diallydialkylammonium monomer is selected from the group consisting of diallyldimethylammonium chloride, diallyldimethylammonium bromide, diallyldimethylammonium sulfate, diallyldimethylammonium phosphate, dimethallyldimethylammonium chloride, diethylallyldimethylammonium chloride, diallyldi(beta-hydroxyethyl) ammonium chloride, diallyldi(beta-ethoxyethyl) ammonium chloride, diallyldiethylammonium chloride and mixtures thereof. ### Claim 14 (depends on 13) A method according to claim 13 wherein at least 50% by weight of the monomer, based on the weight of the entire monomer component or components available for polymerization, is diallyldimethylammonium chloride. ### Claim 15 (depends on 1) The method of claim 1 wherein the paper furnish contains thermal mechanical pulp. ### Claim 16 (depends on 1) The method of claim 1 wherein the paper furnish contains recycled pulp. ### Claim 17 (depends on 1) The method of claim 1 wherein the paper furnish contains coated broke. ### Claim 18 (depends on 1) The method of claim 1 wherein the paper furnish contains deinked pulp. ### Claim 19 (depends on 1) The method of claim 1 wherein the paper furnish contains a mixture of at least two selected from the group consisting of thermal mechanical pulp, recycled pulp, deinked pulp and coated broke. ### Claim 20 (depends on 1) A method according to claim 1, wherein (ii) is run in the presence of base. ### Claim 21 (depends on 1) A method according to claim 1, wherein the amount of additional free radical initiator in (ii) is from about 0.5 to 10% by weight based on the cationic base polymer. ### Claim 22 (depends on 1) A method according to claim 1, wherein the base cationic polymer solution contains less than 1% residual monomer based on the weight of the base polymer. ### Claim 23 (depends on 22) A method according to claim 22, wherein the concentration of the base polymer prior to reaction is from 1 to about 70 percent weight of the solution in (ii).