# US 10,118,990 B2 · Flame-resistant polyamide, method for the production of said flame-resistant polyamide, and use of said flame-resistant polyamide > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,118,990 B2 - Document ID: US10118990B2 - Status: Granted - Kind: B2 - Application number: 15/790,323 - Filed: 2017-10-23 - Published: 2018-02-15 - Granted: 2018-11-06 - Earliest claimed: 2013-03-28 - Assignees: Deutsche Institute Fur Textilund Faserforschung Denkendorf - Applicants: Deutsche Institute FüR Textilund Faserforschung Denkendorf - Inventors: Rainer Gutmann; Sabine Gneiting - Web page: https://patentgrep.com/patent/US10118990B2 ## CPC - C08G 69/42: Polyamides containing atoms other than carbon, hydrogen, oxygen, and nitrogen (C08G69/12, C08G69/32 take precedence) - C08G 69/02: Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids - C08J 5/00: Manufacture of articles or shaped materials containing macromolecular substances (manufacture of semi-permeable membranes B01D67/00 - B01D71/00) - C08J 2377/06: Polyamides derived from polyamines and polycarboxylic acids (C08J2377/10 takes precedence) - C08L 77/06: Polyamides derived from polyamines and polycarboxylic acids (C08L77/10 takes precedence) - C08L 2205/02: containing two or more polymers of the same C08L -group - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS - 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) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) ## Abstract The invention relates to a flame-resistant polyamide as a product of the condensation of dicarboxylic acids with diamines and with a flame-retardant phosphorus compound, which flame-resistant polyamide is characterized in that the flame-resistant polyamide FR contains, in the main chain thereof phosphinic acid amide structural units of formula (II) —PO(R1)—NH— (II) in addition to the amide structural units of formula (I) CO—NH— (I), in which formula (II) RI means hydrogen or an organic group and can differ in the individual phosphinic acid amide structural units within the main chain and that the polyamide FR achieves a relative viscosity, measured as a 1% solution in 96% sulfuric acid at 25° C., of at least 2.0 (in accordance with DIN 51562). The invention further relates to a method for producing said flame-resistant polyamide FR. In said method, one or more diamines are polycondensed with one or more dicarboxylic acids under pressure and at elevated temperature in the presence of water and with one or more diphosphinic acids and/or one or more phosphino-carboxylic acids by means of a polyamide synthesis. After the polycondensation, the pressure in the reaction chamber is reduced to less than 1 bar. The flame-resistant polyamide can be advantageously used to produce molded bodies, in particular films, components, and filaments or filament yarns. ## Claims ### Claim 1 A process for producing a flame-retardant polyamide comprising polycondensation of one or more diamines in the form of a AH salt with one or more dicarboxylic acids under an initial pressure of between 16 and 25 bar at elevated temperature of between 230° C. to 280° C., in the presence of water, in order to build up the pressure in the reactor that is required at the selected reaction temperature, and with one or more diphosphinic acids of the formula (III) and/or with one or more carboxy-phosphinic acids of the formula (IV), the dicarboxylic acid being replaced in part, under the stoichiometric conditions on which the polycondensation is based, by the diphosphinic acid (III) and/or by the carboxy-phosphinic acid (IV), the pressure in the reaction space after the polycondensation being lowered to less than 250 mbar, and wherein the following definitions applying to the formulae (III) and (IV): R2 and R3, independently of one another, are a linear, cyclic or branched C1-C6 alkyl group or an aryl group, and R4 is a divalent organic group, said polycondensation yielding a flame-retardant polyamide FR containing in its main chain not only the amide structural units of the formula (I) —CO—NH— (I) but also phosphinamide structural units of the formula (II) —PO(R1)—NH— (II), R1 being hydrogen or an organic group, and in which individual phosphinamide structural units within the main chain may be different, and in that the polyamide FR attains a relative viscosity, measured as a 1% strength solution in 96% strength sulfuric acid at 25° C., of at least 2.0 and not more than 4.0 (according to DIN 51562), wherein the proportion of the reactants in the form of the diamines, dicarboxylic acids, diphosphinic acids, and the carboxy-phosphinic acids is adjusted such that the phosphorus content of the flame-retardant polyamide process product obtained, based on the polyamide FR, is between 0.01 wt % and 10.0 wt %. ### Claim 2 (depends on 1) The process according to claim 1, wherein the polyamide FR contains 0.01 to 8 wt %, of phosphorus. ### Claim 3 (depends on 1) The process according to claim 1, further comprising the addition of an additive selected from UV stabilizers, heat stabilizers and/or matting agents. ### Claim 4 (depends on 3) The process according to claim 3, further comprising the addition of 0.01 to 1.0 wt % of said additive. ### Claim 5 (depends on 1) The process according to claim 1, wherein the flame-retardant polyamide FR has a nonflammability which meets the mandates of the UL 94 V-0 protocol. ### Claim 6 (depends on 1) The process according to claim 1, wherein the relative viscosity of the flame-retardant polyamide FR (measured according to DIN 51562) attains between at least 2.4 and 4.0. ### Claim 7 (depends on 1) The process according to claim 1, wherein the flame-retardant polyamide FR is based on one of the following diamine and dicarboxylic acid combinations: PA6.9 (hexamethylenediamine/azelaic acid), PA6.12 (hexamethylenediamine/dodecanoic acid), PA4.6 (tetramethylenediamine/adipic acid), PA12.12 (dodecanediamine/dodecanedioic acid) or PA6.6 (hexamethylenediamine/adipic acid). ### Claim 8 (depends on 1) The process according to claim 1, wherein the flame-retardant polyamide FR is combined with a further non flame-retardant polyamide 6 (polycaprolactam). ### Claim 9 (depends on 1) A process according to claim 1, characterized in that the built up pressure is lowered to 1 to 100 mbar. ### Claim 10 (depends on 9) A process according to claim 9, characterized in that the built up pressure is lowered to 1 to 10 mbar. ### Claim 11 (depends on 1) A process according to claim 1, wherein the flame-retardant polyamide FR is mixed with a further, non phosphorus-containing, non flame-retardant polyamide. ### Claim 12 (depends on 1) A process according to claim 1, wherein the amount of water is not more than 25 wt % and at least 10 wt %. ### Claim 13 (depends on 1) A process according to claim 1, wherein R2 and R3 are a C1-C3 alkyl group or an aryl group having up to three fused or unfused rings. ### Claim 14 (depends on 13) The process according to claim 13, wherein the C1-C3 alkyl group is a methyl, ethyl, and/or a 2-propyl group. ### Claim 15 (depends on 1) A process according to claim 1, wherein R2 and R3 are a phenyl, benzyl, naphthyl, phenanthryl, mesityl or tolyl group, an alkylaryl group, a triphenylmethyl group, an arylalkyl group, an i-propylphenyl, t.butylphenyl or nonylphenyl group. ### Claim 16 (depends on 1) A process according to claim 1, wherein R4 is a linear, cyclic or branched C1-C10 alkylene. ### Claim 17 (depends on 1) A process according to claim 1, wherein R4 is a C1-C4 alkylene group, a C1-C10 alkenylene, a C6-C10 arylene or a 1,4-phenylene group. ### Claim 18 (depends on 1) A process according to claim 1, further comprising forming said product as a filament.