United States Patent 19 11 Patent Number: 5,371,263 Quotschalla Et Al
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USOO537263A United States Patent 19 11 Patent Number: 5,371,263 Quotschalla et al. 45. Date of Patent: Dec. 6, 1994 54 PROCESS FOR STABILIZING TRIVALENT O167969 1/1986 European Pat. Off. PHOSPHORUS COMPOUNDS WITH O168721 1/1986 European Pat. Off. AMNES 0278579 8/1988 European Pat. Off. 75) Inventors: Udo Quotschalla, Heppenheim, Primary Examiner-Patricia L. Morris Germany; Helmut Linhart, Reinach, Assistant Examiner-Michael G. Ambrose Switzerland Attorney, Agent, or Firm-Luther A. R. Hall 73 Assignee: Ciba-Geigy Corporation, Ardsley, 57 ABSTRACT N.Y. The invention relates to a process for stabilizing a crys 21 Appl. No.: 129,705 talline organic phosphite or phosphonite against hydro lysis, which comprises introducing a mixture compris 22 Filed: Sep. 30, 1993 ing phosphite or phosphonite, a solvent or solvent mix 30 Foreign Application Priority Data ture, and 0.1 to 100% by weight (relative to phosphite or phosphonite) of an amine and having a temperature Oct. 5, 1992 CH Switzerland ......................... 3104/92 of 50-100° C. as a homogeneous melt into a liquid Nov. 27, 1992 CH Switzerland ......................... 3647/92 crystallization medium whose temperature during the 51 Int. Cl........................... C07F 9/48; CO7F 9/141 addition is maintained 10-70° C. below the tempera 52 U.S. Cl. ...................................................... 558/71 ture of the melt. 58) Field of Search .......................................... 558/71 The phosphites or phosphonites stabilized according to 56 References Cited the invention are distinguished by their excellent resis U.S. PATENT DOCUMENTS tance to hydrolysis and have a long shelf life even at high atmospheric humidity. They can be advanta 3,553,298 1/1971 Hodan et al. ....................... 260/967 geously used as stabilizers for organic material against 3,787,537 1/1974 De Marcq ........................... 260/954 the damaging effect of heat, oxygen, and/or light. FOREIGN PATENT DOCUMENTS O143464 6/1985 European Pat. Off. 12 Claims, No Drawings 5,371,263 1. 2 can be an individual compound or a mixture of com PROCESS FOR STABLIZNG TRIVALENT pounds. PHOSPHORUS COMPOUNDS WITH AMNES In principle, any organic compounds or mixtures of compounds which are liquid in the temperature range The invention relates to a process for increasing the from 10 to 60° C. under atmospheric pressure, do not shelf life of organic phosphites and phosphonites and to cause solvolysis and are capable of dissolving a suffi an organic phosphite or phosphonite stabilized against cient amount of solid phosphite or phosphonite above hydrolysis. 50 C., in some cases up to 100 C., or are sufficiently Organic phosphites and phosphonites are widely used miscible with the melted phosphite or phosphonite, can as heat stabilizers for synthetic polymers. However, O be used as the solvent. For example, sufficient solubility preparation, storage and use of phosphites and phospho or miscibility is given if the homogeneous liquid mixture nites are rendered difficult by the fact that these com can contain up to 15, in particular up to 50, 26 by weight pounds hydrolyze very easily. A particular problem is of phosphite or phosphonite. Examples of suitable sol storage of the material at high atmospheric humidity. vents are alcohols or hydrocarbons or mixtures thereof. Various methods have been proposed for arriving at 5 products having improved stability to hydrolysis; these Advantageously one compound or a mixture of two include, apart from preparation processes leading to compounds is used as the solvent in the melt. The main purer products and methods for purifying the ready-to solvent is used in an amount of 20 to 500% by weight, use compounds, in particular the addition of specific relative to the phosphite orphosphonite, and the further stabilizers which, on the one hand, reduce the tendency solvent in an amount of 0-50% by weight, relative to to hydrolysis and, on the other hand, do not result in the main solvent. The melt preferably contains an alco adverse effects during the later use of the compounds. hol or a hydrocarbon as the main solvent in an amount EP-A-278 579 proposes to use a hydrolytically stable of 20 to 500% by weight, relative to the phosphite or stabilizer mixture in which the crystalline phosphite is phosphonite, and a further solvent in an amount of 0-50, embedded in an amorphous phenolic antioxidant. This 25 in particular 0-20, 26 by weight, relative to the main stabilizer mixture is obtainable by rapid cooling of a Solvent. It is also possible to use a mixture of alcohols or melt of both compounds or of a suspension consisting of a mixture of hydrocarbons. crystalline phosphite and liquid phenol derivatives. Examples of suitable alcohols are lower alcohols, The addition of amines as stabilizers against hydroly such as C1-C5alkanols, in particular C1-C3alkanols, sis is described, for example, in U.S. Pat. No. 3,553,298. 30 such as methanol, ethanol, propanol or isopropanol. Further publications regarding the stabilizing of phos Isopropanol and methanol are particularly suitable. phites with amines are U.S. Pat. No. 3,787,537, EP-A- Examples of suitable hydrocarbons are C6-C13al 168 721 and EP-A-167969. The recommended com kanes, cycloalkanes or alkylated cycloalkanes having 6 pounds are in particular tertiary alkanolamines and to 12 carbon atoms, benzene, or alkylaromatics having 6 alkylamines, pyridines and anilines; typical examples are 35 to 10 atoms; toluene, ligroin, petroleum ether, xylene, triethylamine, diethanolamine, triethanolamine, di- and and in particular toluene are particularly suitable. triisopropanolamine (TIPA), tetraisopropanole Frequently the further solvent used is a hydrocarbon thylenediamine, aniline, phenylenediamine and hexa or a mixture of hydrocarbons in the case where the main methylenetetramine. In general, the amines are used in solvent is an alcohol, or an alcohol in the case where the amounts of up to about 5% by weight (relative to the main solvent is a hydrocarbon. Suitable alcohols and phosphite to be stabilized); incorporation of the amine is hydrocarbons are the ones listed above. effected by dry milling or by dissolution in or mixing The organic phosphites or phosphonites usable ac with the phosphite melt, followed by crystallization. cording to the invention are solid at 20 C.; in general Despite the known stabilization methods listed here, they are crystalline solids. there is a need for further improvement of the hydro 45 Phosphites are here understood to mean organic lytic stability of organic phosphites and phosphonites. phosphites of the formula P(OR)3 in which the radicals It has now been found that the stabilizing effect of Rare hydrocarbon radicals, which may contain hetero amines can surprisingly be increased by applying the atoms, and moreover a maximum of two of the three amine in a special process. radicals R can be hydrogen atoms. Hetero atoms are Accordingly, the invention provides a process for 50 any atoms with the exception of carbon and hydrogen, stabilizing a crystalline organic phosphite or phospho in particular the atoms N, O, F, Si, P, S, Cl, Br, Sn and nite against hydrolysis, which comprises introducing a I. mixture comprising phosphite or phosphonite, a solvent Phosphonites are esters of phosphonous acid of the or solvent mixture, and 0.1 to 100% by weight (relative formula P(OR)2R in which R is as defined above or can to the phosphite or phosphonite) of an amine and hav 55 be halogen. ing a temperature of 50-100 C. as a homogeneous melt In the process according to the invention, crude into a liquid crystallization medium whose temperature phosphite or crude phosphonite solutions such as are during the addition is maintained 10-70° C. below the obtained during preparation before crystallization can temperature of the melt. be used. The melt is the liquid mixture comprising amine, 60 The product of the process according to the inven solvent and the phosphite or phosphonite to be stabi tion is a mixture of compounds comprising solid phos lized. The melt can contain a small or a large amount of phite or phosphonite and amine. solvent, for example 20 or 500% by weight (relative to The temperature of the melt is preferably 55°-90° C., the phosphite orphosphonite) and thus can also be more in particular 60-80 C. like a solution. The important feature is that the melt is 65 In the process according to the invention, the differ homogeneous, i.e. that none of the components men ence in temperature between melt and crystallization tioned are crystalline any more and separation into 2 or medium is advantageously at least 20 C., for example more liquid phases does not take place. The amine used 30-70° C., in particular 40-60 C. 5,371,263 3 4. The crystallization medium is preferably maintained or -C2H4-NX-C2H4-, m being an integer from at a temperature being at least 10 C., for example the range 4 to 6 and X1 and X2 being as defined above. 10-60C., below the resulting temperature of the liqui The sterically hindered amine is in general a cyclic dus. The temperature of the crystallization medium is sterically hindered amine, in particular a compound preferably 20-60 C. below the resulting temperature 5 from the series of polyalkylpiperidine or -piperazine of the liquidus. derivatives containing a group of the formulae II or III The resulting temperature of the liquidus is the tem perature at which a homogeneous phase formed from the melt and crystallization medium is in thermody CH3 (II) namic equilibrium with phosphite crystals; below this O temperature, crystallization starts, and above the mix ture forms a homogeneous melt. In practice, this tem perature is advantageously determined by mixing tests, for example by means of calorimetric (for example by G-CH2 DSC) and/or optical methods. 15 CH3 Advantageously, 80-800% by weight, in particular 10-500% by weight, of organic solvent, relative to the phosphite or phosphonite in the melt, is used as the CH3 G1 (III) crystallization medium.