# US 9,040,600 B2 · Process for the preparation of expandable polystyrene by continuous injection of a liquid organic peroxide > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,040,600 B2 - Document ID: US9040600B2 - Status: Granted - Kind: B2 - Application number: 13/386,958 - Filed: 2010-07-22 - Published: 2012-06-07 - Granted: 2015-05-26 - Earliest claimed: 2009-07-27 - Assignees: Arkema France - Applicants: Pascal Nicol; Jacques Cochet - Inventors: Pascal Nicol; Jacques Cochet - Web page: https://patentgrep.com/patent/US9040600B2 ## CPC - C08J 9/20: by suspension polymerisation in the presence of the blowing agent - C08F 2/18: Suspension polymerisation - C08F 4/34: Per-compounds with one peroxy-radical - C08F 4/38: Mixtures of peroxy-compounds - C08J 9/0023: {containing oxygen} - C08J 9/141: {Hydrocarbons} - C08J 2203/14: Saturated hydrocarbons, e.g. butane; Unspecified hydrocarbons - C08J 2325/04: Homopolymers or copolymers of styrene - C08J 2325/06: Polystyrene - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS ## Abstract A process for the preparation of expandable polystyrene including the following steps: i°) heating an aqueous suspension including styrene monomer and at least one organic peroxide initiator of formula (I) 1-alkoxy-1-t-alkylperoxycyclohexane in which the alkoxy group contains 1 to 4 carbon atoms, the t-alkyl group contains 4 to 12 carbon atoms, and the cyclohexane ring may optionally be substituted with 1 to 3 alkyl groups each, independently having 1 to 3 carbon atoms, at a temperature ranging from 100° C. to 120° C., ii°) adding a blowing agent selected from the group of alkanes having from 4 to 6 carbon atoms and mixtures thereof. Also, an expandable polystyrene obtainable according to such a process and to insulation parts and packaging including such an expandable polystyrene. ## Claims ### Claim 1 Process for the preparation of expandable polystyrene comprising the following steps: I°)a) preparing an aqueous suspension comprising styrene monomer and at most 40% by weight of at least one organic peroxide initiator of formula (I), based on total weight of the peroxide used during polymerization, I°)b) heating the suspension at a polymerisation temperature ranging from 100° C. to 120° C., I°)c) adding by continuous addition over a period of about 2 hours to about 4 hours, before, during and/or after step I°)b) a remaining amount of the at least one organic peroxide initiator of formula (I) while present as a dilute solution or dispersion and an additional peroxide initiator of formula (II) in pure form after at least 5% of said styrene monomer has been polymerized where: (I) is 1-alkoxy-1-t-alkylperoxycyclohexane, in which the alkoxy group contains 1 to 4 carbon atoms, the t-alkyl group contains 4 to 12 carbon atoms, and the cyclohexane ring may optionally be substituted with 1 to 3 alkyl groups each, independently having 1 to 3 carbon atoms, and (II) is OO-t-alkyl-O-alkyl monoperoxycarbonate wherein t-alkyl contains from 4 to 12 carbon atoms and alkyl contains 3 to 12 carbon atoms, and their mixtures, and ii°) adding a blowing agent selected from the group consisting of alkanes having from 4 to 6 carbon atoms and mixtures thereof; wherein the expandable polystyrene has a maximum molecular weight of 206,000 g/mol and a minimum molecular weight of 170,000 g/mol. ### Claim 2 (depends on 1) Process according to claim 1, wherein the at least one organic peroxide initiator of formula (I) is 1-methoxy-1-t-amylperoxycyclohexane (TAPMC). ### Claim 3 (depends on 1) Process according to claim 1, wherein said blowing agent is selected from the group consisting of butane, 2-methylbutane, pentane, cyclohexane and mixtures thereof. ### Claim 4 (depends on 1) Process according to claim 1, wherein at most 5% by weight (% w/w) of organic peroxide initiator of formula (I), based on the total weight of the peroxide used during the polymerization, is present before step I°)b), while the remaining amount is added by continuous addition over a period of at least 1 hour during or after step I°)b). ### Claim 5 (depends on 1) Process according to claim 1, wherein the temperature of step i°) ranges from 105° C. to 115° C. ### Claim 6 (depends on 1) Process according to claim 1, wherein said additional peroxide initiator is of formula (II): (II) OO-t-alkyl-O-alkyl monoperoxycarbonate, wherein t-alkyl contains from 4 to 5 carbon atoms, and alkyl contains from 3 to 12 carbon atoms, and their mixtures. ### Claim 7 (depends on 1) Process according to claim 1, wherein said organic peroxide initiator of formula (I) is used in the aqueous suspension of step i°) in amounts from 4 to 25 milli equivalents of initiator per liter of styrene. ### Claim 8 (depends on 1) Process according to claim 1, wherein the styrene monomer to be polymerized also contains up to 15 weight %, with respect to the total weight of styrene, of copolymerizable monomers other than styrene monomers. ### Claim 9 (depends on 1) Process according to claim 1, wherein hexabromocyclododecane is added to the aqueous suspension at step i°) or at step ii°). ### Claim 10 (depends on 1) Process according to claim 1, wherein the aqueous suspension of step i°) comprises the organic peroxide initiator of formula (I) as first stage initiator and the at least one additional other organic peroxide initiator of formula (II) as second stage initiator, step i°) comprises a stage I°)b′), during which said suspension is heated at a temperature ranging from 100° C. to 120° C., and a second stage I°)c′) during which said suspension is heated at a temperature corresponding to the one hour half life temperature of the at least additional other organic peroxide of formula (II). ### Claim 11 (depends on 1) Process according to claim 1, wherein the additional peroxide initiator of formula (II) is OO-t-amyl-O-2-ethylhexyl monoperoxycarbonate (TAEC). ### Claim 12 (depends on 1) Process according to claim 1, wherein the additional peroxide initiator of formula (II) is OO-t-butyl-O-2-ethylhexyl monoperoxycarbonate (TBEC). ### Claim 13 (depends on 1) Process according to claim 1, wherein the resulting expandable polystyrene has a molecular weight of at least 175,000 g/mol. ### Claim 14 (depends on 1) Process according to claim 1, wherein the resulting expandable polystyrene has a molecular weight of at least 190,000 g/mol. ### Claim 15 Process for the preparation of expandable polystyrene comprising the following steps: I°)a) preparing an aqueous suspension comprising styrene monomer and at most, 40% by weight of a first peroxide initiator, based on total weight of the peroxide used during polymerization, I°)b) heating the suspension at a polymerisation temperature ranging from 100° C. to 120° C., I°)c) adding by continuous addition over a period of about 2 hours to about 4 hours, before, during and/or after step I°)b) at least one additional organic peroxide initiator of formula (I) while present as a dilute solution or dispersion, wherein the first peroxide initiator is different from the organic peroxide initiator of formula (I) where: (I) is 1-alkoxy-1-t-alkylperoxycyclohexane, in which the alkoxy group contains 1 to 4 carbon atoms, the t-alkyl group contains 4 to 12 carbon atoms, and the cyclohexane ring may optionally be substituted with 1 to 3 alkyl groups each, independently having 1 to 3 carbon atoms, and ii°) adding a blowing agent selected from the group consisting of alkanes having from 4 to 6 carbon atoms and mixtures thereof; wherein the expandable polystyrene has a maximum molecular weight of 206,000 g/mol and a minimum molecular weight of 170,000 g/mol. ### Claim 16 (depends on 15) Process according to claim 15, wherein the first peroxide initiator is added in pure form. ### Claim 17 (depends on 15) Process according to claim 15, wherein the first peroxide initiator is of formula (II): (II) OO-t-alkyl-O-alkyl monoperoxycarbonate wherein t-alkyl contains from 4 to 12 carbon atoms and alkyl contains 3 to 12 carbon atoms, and their mixtures.