# US 5,707,493 A · Temperature-activated polysilicic acids in paper production > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,707,493 A - Document ID: US5707493A - Status: Granted - Kind: A - Application number: 08/592,950 - Filed: 1996-01-29 - Granted: 1998-01-13 - Earliest claimed: 1995-01-20 - Assignees: J.M. Huber Corporation - Inventors: Sakari Saastamoinen - Web page: https://patentgrep.com/patent/US5707493A ## CPC - D21H 21/10: Retention agents or drainage improvers - C01B 33/143: of aqueous solutions of silicates - C01B 33/1435: {using ion exchangers} - D21H 17/68: siliceous, e.g. clays - 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 - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} ## Abstract A temperature-activated polysilicic acid is prepared by heating an acidified aqueous alkali metal silicate. The temperature-activated polysilicic acid is used in the production of paper for improvement of retention and water removal. ## Claims ### Claim 1 A process for the production of paper comprising the steps of: adding components comprising a temperature-activated polysilicic acid having a specific surface area of at least about 1350 m.sup.2 /g and a cationic polymer to an aqueous fiber pulp suspension, said components being added in an amount to enhance at least one paper/paper processing characteristic selected from the group consisting of filler retention, water removal, paper mechanical properties, fine and colloid recovery, and filterability; and, carrying out sheet formation and water removal; wherein the temperature-activated polysilicic acid is produced by a process comprising the steps of heating an acidified aqueous alkali metal silicate at a temperature of about 30.degree. to 250.degree. C. at a pH of about 0 to 5. ### Claim 2 (depends on 1) The process of claim 1, wherein the aqueous fiber pulp suspension contains a filler. ### Claim 3 (depends on 1) The process of claim 1, wherein the temperature-activated polysilicic acid has a pH of about 0 to 2. ### Claim 4 (depends on 1) The process of claim 1, wherein the acidified aqueous alkali metal silicate is prepared by slow addition of a diluted alkali metal silicate solution into a mineral acid. ### Claim 5 (depends on 4) The process of claim 4, wherein the mineral acid is selected from the group consisting of sulfuric acid, hydrochloric acid or phosphoric acid. ### Claim 6 (depends on 1) The process of claim 1 wherein the aqueous alkali metal silicate is acidified by slow addition of a diluted alkali metal silicate solution into an ion exchange agent or an organic acid such as acetic acid. ### Claim 7 (depends on 5) The process of claim 5, wherein the aqueous alkali metal silicate is sodium silicate. ### Claim 8 (depends on 1) The process of claim 1, wherein the acidified aqueous alkali metal silicate is heated at a temperature of about 30.degree. to 250.degree. C. for about 1 to 120 hours. ### Claim 9 (depends on 8) The process of claim 8, wherein the acidified aqueous alkali metal silicate is heated at a temperature of 60.degree. C. for 20 hours. ### Claim 10 (depends on 1) The process of claim 1, wherein the acidified aqueous alkali metal silicate is heated under pressure necessary to achieve a desired temperature. ### Claim 11 (depends on 1) The process of claim 1, wherein the heated and acidified aqueous alkali metal silicate is mixed at room temperature and diluted. ### Claim 12 (depends on 11) The process of claim 11, wherein the heated and acidified aqueous alkali metal silicate is subsequently mixed at room temperature for 72 hours and diluted to 0.15% SiO.sub.2. ### Claim 13 (depends on 1) The process of claim 1, wherein the temperature-activated polysilicic acid has a specific surface area of about 1350 to 1600 m.sup.2 /g. ### Claim 14 (depends on 1) The process of claim 1, wherein the cationic polymer is selected from the group consisting of starch, polyacrylamide, guar gum, or a mixture thereof. ### Claim 15 (depends on 1) The process of claim 1, wherein the temperature-activated polysilicic acid is added to the suspension in an amount of from about 0.05-5 wt. % based on dry weight of the fiber. ### Claim 16 (depends on 1) The process of claim 1, wherein the cationic polymer is added to the suspension in an amount of from about 0.005-5 wt. % based on dry weight of the fiber. ### Claim 17 (depends on 1) A paper product produced according to the process of claim 1. ### Claim 18 A method for improving retention in a papermaking process wherein a temperature-activated polysilicic acid having a specific surface area of at least about 1350 m.sup.2 /g and a cationic polymer are added to an aqueous fiber pulp suspension, said polysilicic acid being added in an amount to enhance filler retention; wherein the temperature-activated polysilicic acid is produced by a process comprising the steps of heating an acidified aqueous alkali metal silicate at a temperature of about 30.degree. to 250.degree. C. at a pH of about 0 to 5. ### Claim 19 (depends on 18) The method of claim 18, wherein the acidified aqueous alkali metal silicate is heated with secondary heat from a paper mill. ### Claim 20 (depends on 18) The method of claim 18, wherein the temperature-activated polysilicic acid has a pH of about 0 to 2. ### Claim 21 (depends on 18) The method of claim 18, wherein the acidified aqueous alkali metal silicate is prepared by slow addition of a diluted alkali metal silicate solution into a mineral acid. ### Claim 22 (depends on 21) The method of claim 21, wherein the mineral acid is selected from the group consisting of sulfuric acid, hydrochloric acid or phosphoric acid. ### Claim 23 (depends on 18) The process of claim 18, wherein the aqueous alkali metal silicate is acidified by slow addition of a diluted alkali metal silicate solution into an ion exchange agent or an organic acid such as acetic acid. ### Claim 24 (depends on 22) The method of claim 22, wherein the aqueous alkali metal silicate is sodium silicate. ### Claim 25 (depends on 18) The method of claim 18, wherein the acidified aqueous alkali metal silicate is heated at a temperature of about 30.degree. to 250.degree. C. for about 1 to 120 hours. ### Claim 26 (depends on 25) The method of claim 25, wherein the acidified aqueous alkali metal silicate is heated at a temperature of 60.degree. C. for 20 hours. ### Claim 27 (depends on 18) The method of claim 18, wherein the acidified aqueous alkali metal silicate is heated under pressure necessary to achieve a desired temperature. ### Claim 28 (depends on 18) The method of claim 18, wherein the heated and acidified aqueous alkali metal silicate is mixed at room temperature and diluted. ### Claim 29 (depends on 28) The method of claim 28, wherein the heated and acidified aqueous alkali metal silicate is subsequently mixed at room temperature for 72 hours and diluted to 0.15% SiO.sub.2. ### Claim 30 (depends on 18) The method of claim 18, wherein the temperature-activated polysilicic acid has a specific surface area of about 1350 to 1600 m.sup.2 /g. ### Claim 31 (depends on 18) The method of claim 18, wherein the temperature-activated polysilicic acid is added to the suspension in an amount of from about 0.05-5 wt. % based on dry weight of the fiber. ### Claim 32 (depends on 18) A paper product produced according to the method of claim 18.