United States Patent (19) 11) 3,888,822 Gilleo et al. (45) June 10, 1975 54) PROCESS FOR INCREASING FLAME 56) References Cited RESISTANCE OF NYLON AND RESULTING UNITED STATES PATENTS FLAME RESISTANT NYLON 3,250,772 5/1966 Dexter et al................. 260/45.8 NT COMPOSITION 3,293,249 12/1966 Biland et al................. 260/45.8 NT (75) Inventors: Kenneth B. Gilleo, Depew, Francis 3,415,824 12/1968 Biland et al................. 260/45.8 NT 3,444, 142 5/1969 Kolyer et al................. 260/45.8 NT E. Evans, Hamburg; Allen W. Sogn, 3,538,092 1 1/1970 Dexter et al................. 260/45.8 NT Williamsville, all of N.Y. 3,709,883 1/1973 Dexter et al................. 260/45.8 NT 73. Assignee: Allied Chemical Corporation, New 3,793,289 2/1974 Koch et al................... 260/45.8 NT York, N.Y. Primary Examiner-Melvyn I. Marquis 22 Filed: Dec. 17, 1973 Attorney, Agent, or Firm-Michael L. Dunn; Jay P. 21 Appl. No.: 425,488 Friedenson 52) U.S. Cl................... 260/45.8 NT, 260/45.75 R, 57 ABSTRACT 26045.75 C, 260/45.8 N A process for increasing the flame resistance of nylon 51) Int. Cl. ............................................ C08f 45/58 comprising treating the nylon with a heterocyclic ring (58) Field of Search 260/45.8 NT, 45.8 N, 45.75 R, compound which contains both sulfur and nitrogen 260/45.75 C and the resulting flame resistant nylon composition. 41 Claims, No Drawings 3,888,822 1. 2 PROCESS FOR INCREASING FLAME RESISTANCE bonded to a carbon atom and no phosphorous or arse OF NYLON AND RESULTING FLAME RESISTANT nic. NYLON COMPOSITION The novel composition in accordance with the inven tion comprises nylon containing from about 0.5 to This invention relates to nylons exhibiting improved 5 about 25 weight percent of a compound or a mixture flame resistance. More specifically, this invention re of compounds having the above formula. lates to nylon treated with compositions which impart improved flame resistance thereto and to the process of DETAILED DESCRIPTION OF THE INVENTION so treating the nylon. In accordance with this invention nylon is treated In the prior art numerous compounds have been used 10 with at least about 0.5 weight percent and preferably at as additives to carbon containing polymers, including least about 2 weight percent of a compound or a mix nylon (polycarbonamides), to reduce flammability of ture of compounds falling within the above formula. the polymers. For example inorganic and organic tin Generally less than about 25 weight percent, preferably compounds and halogen containing compounds have less than about 16 weight percent, and most preferably been used to reduce flammability of nylon. These com 15 less than about 8 weight percent of the compound or pounds have not, however, been entirely successful. mixture of compounds is used since generally greater In addition to the tin containing compounds and hal percentages do not materially increase flame resistance ogen containing compounds, some compounds, con and can sometimes cause undesirable effects such as taining nitrogen and sulfur have been employed to im flaking on the surface of the nylon. prove flame resistance. For example thiourea and com 20 The nylon may be treated by wetting the surface with pounds containing non-cyclic imine groups have been a solution or emulsion containing one or more of the used. Thiourea, while being an improvement over the above compounds or one or more of the compounds tin and halogen compounds, still does not create as may be added to the nylon polymerization reactants or much flame resistance as is desired, or necessary, and to the nylon melt prior to the formation of polymeric the compounds containing imine groups do not give the 25 products, e.g. a nylon fiber. desired flame resistance and, due to the imine group, The compounds which are added to the nylon poly hydrolize when contacted with water thus preventing merization reactants should of course be stable under the formation of a permanent application of the com the conditions of polymerization, should not interfere pounds to the nylon or other carbon containing poly with the polymerization and should be stable in the IeS. 30 nylon melt. An example of such a compound is: Other compounds containing both sulfur and nitro gen which have been suggested to impart flame resis tance to nylon have been found to be inadequate since HS N SLil' they contain too much carbon in relation to the amount N of other elements present in the compound or the car 35 Y's bon is present in a single flammable chain of excessive length, which chain will easily burn. NS BRIEF DESCRIPTION OF THE INVENTION H In accordance with the process of this invention it has 40 now been discovered that nylon can be treated with Compounds added to the nylon melt should be stable certain additive compounds containing sulfur and ni in the melt and should not deleteriously affect the ny trogen to give a flame resistance which is superior to lon. Examples of such compounds are: the flame resistance obtainable by any known prior art compound or method. 45 The additive compounds, with which the nylon is treated, have the formula: wherein Q is a saturated or unsaturated heterocyclic 50 Mg't ring structure, which may be substituted or unsubsti tuted, containing at least one sulfur or nitrogen atom in the ring; R1 is independently at each occurrence a mon ovalent radical containing at least one sulfur or nitro gen atom; R2 is independently at each occurrence a di 55 valent radical containing at least one sulfur or nitrogen S N - * atom; n is 0 or an integer of 1 through 6 and m is 0 or Y Catt HS YN s NH an integer of 1 through 3 and the sum of n and 2m is N. N no greater than six with the proviso that said compound Y N 2 N 60 S 2 and N contains at least one nitrogen atom and at least one sul -- H - SH fur atom, contains no non-cyclic imine group, and the ratio of the number of carbon atoms in the compound to the total number of atoms having an atomic number greater than 2 other than carbon in the compound being 2:1 or less, said compound including no carbon 65 Q in the above formula for the compounds may be chain containing over six and preferably not over five any substituted or unsubstituted heterocyclic ring con carbon atoms, no hexavalent sulfur which is directly taining at least one sulfur or nitrogen atom in the ring. 3,888,822 3 4 The substituents e.g. -COOH or -OH upon the ring be hexavalent only if it is not directly connected to a should of course not contribute to flammability al carbon atom, and the compound contains no halogen though hydrogen and small amounts of carbon can be or phosphorous since halogen or phosphorous tends to: tolerated. The heterocyclic ring, exclusive of substitu degrade nylon and since it is believed that the presence, ents, contains from four through six atoms; and con of phosphorous and halogen tends to form toxic prod tains either sulfur or nitrogen, preferably both. Three ucts during combustion. Arsenic is also not used be membered rings are unsuitable and not included in that cause of possible toxic products. they are unstable. Examples of some preferred R radicals are -SH; Examples of suitable heterocyclic rings, Q, which -NRR4 wherein Ra and R are independently at each may be saturated or unsaturated, are: six membered 10 occurrence hydrogen or methyl; rings containing nitrogen including azine, diazine, tri azine, tetrazine and pentazine rings; six membered rings containing sulfur including dithiin and thiopyran -sals; als; : NH2 -i. liais: rings; six membered rings containing both nitrogen and sulfur including thiatriazine, thiadiazine, dithiadiazine, 15 dithiazine and thiazine rings; five membered rings con -se: -se: -sists -SCH3; taining nitrogen including azole, diazole, triazole and tetrazole rings; five membered rings containing sulfur -SCHa;-SCN; or -SM wherein M is an ion having including thiole and dithiole rings; five membered rings a single positive charge preferably selected from simple containing both nitrogen and sulfur including thiazole 20 or complex ions of ammonium, Li, Na, K, Cs, Mg, Sn, and thiadiazole rings; four membered rings containing Ni, Cu, Ti, Zr, Cr, Mn, Fe, Co., Zn and Al. As used nitrogen including azete, diazete and triazete rings; herein "complex ion' means an ion formed by the four membered rings containing sulfur including thie combination of an ion of one of the above listed metals tane rings and four membered rings containing both with another ion or with an atom or molecule. Exam sulfur and nitrogen including thiazete rings. 25 ples of complex ions contemplated by this invention Preferably Q is triazine, diazine, thiatriazine, thiadia are: "CaA, MgA, Sna, "Snas, NiA2, CuA, TiA, zine, triazole, diazole, thiazole and thiadiazole rings, TiA, ZrA, CrA, CrA, MnA, MinA, FeA, since the five and six membered rings are generally *Fea, CoA, CoA, ZnA, AIA, SnaD, NiD, more stable than the four membered rings and since the TiD, TiAD, “ZrAD, “CrD, “MnD, “FeD, “CoD, rings containing more nitrogen and sulfur atoms in rela 30 “AlD, “SnPO, TiPO, and ZrPO, where A indepen tion to the number of carbon atoms provide less fuel for dently at each occurrence is halogen, BO, or combustion. The heterocyclic rings containing both sulfur and ni trogen in themselves impart good flame resistance in S--(R2) accordance with this invention but may be even further 35 is: improved through the addition of appropriate substitu where Ri, R, n, m and Q are as defined herein; and ent groups R and R2.