# US 10,765,115 B2 · Method for suppressing reduction of isothiazoline compound concentration > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,765,115 B2 - Document ID: US10765115B2 - Status: Granted - Kind: B2 - Application number: 15/773,623 - Filed: 2016-03-28 - Published: 2019-02-28 - Granted: 2020-09-08 - Earliest claimed: 2015-11-09 - Assignees: Kurita Water Industries Ltd. - Applicants: Kurita Water Industries Ltd. - Inventors: Takashi Iyasu; Yasushi Murano; Toshimasa Kato - Web page: https://patentgrep.com/patent/US10765115B2 ## CPC - A01N 43/80: five-membered rings with one nitrogen atom and either one oxygen atom or one sulfur atom in positions 1,2 - A01N 25/22: containing ingredients stabilising the active ingredients - A01N 59/00: Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds - A01P 1/00: Disinfectants; Antimicrobial compounds or mixtures thereof - C02F 1/50: by addition or application of a germicide or by oligodynamic treatment {(C02F1/4606, C02F1/467, C02F1/76 take precedence)} - C02F 1/76: with halogens or compounds of halogens {(C02F1/4674 takes precedence)} - C02F 1/441: {by reverse osmosis} - C02F 2103/023: {Water in cooling circuits} - C02F 2103/28: from the paper or cellulose industry - C02F 2303/04: Disinfection - C02F 2303/08: Corrosion inhibition - C02F 2303/12: Prevention of foaming - C02F 2303/20: Prevention of biofouling - C02F 2303/22: Eliminating or preventing deposits, scale removal, scale prevention (C02F1/042, C02F1/4602, C02F5/00 take precedence) - A01N: PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF (preservation of food or foodstuff A23); BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES (preparations for medical, dental or toiletry purposes which kill or prevent the growth or proliferation of unwanted organisms A61K); PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS - A01P: BIOCIDAL, PEST REPELLANT, PEST ATTRACTANT OR PLANT GROWTH REGULATORY ACTIVITY OF CHEMICAL COMPOUNDS OR PREPARATIONS - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) ## Abstract The present invention provides a method for suppressing a decrease in the concentration of an isothiazoline compound, wherein even if an addition concentration of the isothiazoline compound used as an antibacterial agent is low in a water system, the decrease in the concentration thereof can be suppressed so that the residual rate thereof after 24 hours can be raised. The method is carried out in a manner wherein to a water system, an isothiazoline compound is fed with an addition concentration of 0.2 mg/L or more and less than 1 mg/L, and a combined chlorine agent consisting of a chlorine stabilizer and a chlorine-based oxidant is added so as to maintain a concentration thereof at 0.3 mg/L as Cl2 or more and 6 mg/L as Cl2 or less therein. ## Claims ### Claim 1 A method for suppressing a decrease in concentration of an isothiazoline compound, the method comprising: feeding an isothiazoline compound to a water system, with an addition concentration of 0.2 mg/L or more and less than 1 mg/L; and adding a combined chlorine agent consisting of a chlorine stabilizer and a chlorine-based oxidant to the water system, so as to maintain a concentration of the combined chlorine agent in the water system at 0.3 mg/L as Cl2 or more and 6 mg/L as Cl2 or less; wherein a residual concentration of the isothiazoline compound after 24 hours is 15% or more. ### Claim 2 (depends on 1) The method according to claim 1, wherein the isothiazoline compound is at least one selected from the group consisting of 5-chloro-2-methyl-4-isothiazoline-3-one, 2-methyl-4-isothiazoline-3-one, 4,5-dichloro-2-methyl-4-isothiazoline-3-one, 2-ethyl-4-isothiazoline-3-one, 2-n-octyl-4-isothiazoline-3-one, 5-chloro-2-ethyl-4-isothiazoline-3-one, 5-chloro-2-t-octyl-4-isothiazoline-3-one, 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one, 4,5-dichloro-2-cyclohexyl-4-isothiazoline-3-one, and 1,2-benzoisothiazoline-3-one. ### Claim 3 (depends on 1) The method according to claim 1, wherein the chlorine stabilizer is at least one selected from the group consisting of sulfamic acid and derivatives thereof. ### Claim 4 (depends on 1) The method according to claim 1, wherein the chlorine-based oxidant is a hypochlorite salt. ### Claim 5 (depends on 1) The method according to claim 1, wherein the water system is an open circulation cooling water system or a membrane concentrating water system. ### Claim 6 A method for suppressing a decrease in concentration of an isothiazoline compound, the method comprising feeding an isothiazoline compound into a water system comprising a combined chlorine agent consisting of a chlorine stabilizer and a chlorine-based oxidant, wherein: a concentration of the combined chlorine agent in the water system is 0.3 mg/L as Cl2 or more and 6 mg/L as Cl2 or less; the isothiazoline compound is fed into the water system with an addition concentration of 0.2 mg/L or more and less than 1 mg/L; and a residual concentration of the isothiazoline compound after 24 hours is 15% or more. ### Claim 7 (depends on 6) The method according to claim 6, wherein the isothiazoline compound is at least one selected from the group consisting of 5-chloro-2-methyl-4-isothiazoline-3-one, 2-methyl-4-isothiazoline-3-one, 4,5-dichloro-2-methyl-4-isothiazoline-3-one, 2-ethyl-4-isothiazoline-3-one, 2-n-octyl-4-isothiazoline-3-one, 5-chloro-2-ethyl-4-isothiazoline-3-one, 5-chloro-2-t-octyl-4-isothiazoline-3-one, 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one, 4,5-dichloro-2-cyclohexyl-4-isothiazoline-3-one, and 1,2-benzoisothiazoline-3-one. ### Claim 8 (depends on 6) The method according to claim 6, wherein the chlorine stabilizer is at least one selected from the group consisting of sulfamic acid and derivatives thereof. ### Claim 9 (depends on 6) The method according to claim 6, wherein the chlorine-based oxidant is a hypochlorite salt. ### Claim 10 (depends on 6) The method according to claim 6, wherein the water system is an open circulation cooling water system or a membrane concentrating water system.