Polyolefin compositions stabilized with long chain N,N-dialkylhydroxylamines

Abstract: Long chain N,N-dialkylhydroxylamines of the formula I T₁T₂NOH (I) wherein T₁ and T₂ are independently alkyl of 12 to 18 carbon atoms, represent particularly valuable process stabilizers for polyolefin compositions. The hydroxylamine derived from di(hydrogenated tallow)amine is particularly useful for this purpose. These long chain N,N-dialkyl­ hydroxylamines are very resistant to extraction from polyolefin compo­ sitions.

Description: This invention pertains to polyolefin compositions stabilized with long chain N,N-dialkylhydroxylamines. US-A-3,644,278 and US-A-3,778,464 describe the use of N,N-dibenzylhydroxylamine and selected other substituted hydroxylamines as stabilizers for polypropylene. There is no mention of the N,N-dialkylhydroxylamines as possible stabilizers for such polyolefin compositions in these patents. US-A-4,590,231 describes the use of hydroxylamines including the N,N-dialkylhydroxylamines as stabilizers for polyolefin compositions. The N,N-dialkylhydroxylamines are described generically as having alkyl of 1 to 18 carbon atoms and N,N-dioctylhydroxylamine is specifically disclosed as useful in such compositions. There is no mention of the longer chain N,N-dialkylhydroxylamines which are the subject of this invention. The stabilized polyolefin compositions described in this prior art patent also contain an alkaline metal salt of a fatty acid and a phenolic antioxidant. The compositions may optionally also contain a hindered amine light stabilizer or an organic phosphorus compound. US-A-3,408,422 describes the stabilization of unsaturated polyester compositions using various hydroxyl amines. US-A-3,644,244 describes the use of hydroxylamines including the N,N-dialkylhydroxylamines as stabilizers to prevent the gelation of organosols of butadiene/acrylonitrile graft copolymers. US-A-4,242,224 describes the use of dialkylhydroxylamines to reduce or retard the pink discoloration found in amine antioxidant and antiozonant emulsions used in the rubber industry. US-A-4,316,996 pertains to the use of hydroxylamine compounds which can prevent the discoloration of phenolic antioxidants in rubber compositions. US-A-4,547,532 pertains to the use of hydroxylamines to prevent the premature increase in viscosity of polymer-based antifouling paints containing an organotin compound. US-A-4,409,408 discloses the use of N,N-dialkylhydroxylamines and tertiary alkylcatechols in stabilizing vinyl aromatic compounds, such as styrene, against premature polymerization. L.A. Harris et al., J. Am. Oil Chemists Soc. 43, 11 (1966) disclose hydroxylamines which have antioxidant activity in squalene. US-A-3,770,847 discloses hydroxylamines as curing catalysts for organopolysiloxane compositions. The lower alkyl hydroxylamines are superior for this puprose. US-A-4,298,678 pertains to photosensitive compositions which contain substituted hydroxylamines. US-A-3,222,334 discloses N,N-dialkylhydroxylamines as short-stopping agents for emulsion polymerization and US-A-3,341,487 describes a process for stopping emulsion polymerization by the addition of dithiocarbamate salts and alkyl hydroxylamines. None of these references describes the very long chain N,N-dialkylhydroxylamines of over 14 carbon atoms nor does any of said references suggest that the long chain N,N-dialkylhydroxylamines of the instant invention exhibit special properties not possessed by the lower alkyl N,N-dialkylhydroxylamines which are usually the preferred embodiments in the cited prior art. The instant invention pertains to stabilized compositions which comprise (a) a saturated polyolefin or mixture thereof, and (b) a long chain N,N-dialkylhydroxylamine of the formula I T₁T₂NOH wherein T₁ and T₂ are independently hexadecyl, heptadecyl or octadecyl, with the proviso that, if T₁ and T₂ have the same meaning, they are not octadecyl. The instant invention pertains also to stabilized compositions which comprise (a) a saturated polyolefin or mixture thereof, and (b) a long chain N,N-dialkylhydroxylamine of the formula II T₃T₄NOH wherein T₃ and T₄ are the alkyl mixture found in hydrogenated tallow amine.. wherein T₃ and T₄ are the alkyl mixture found in hydrogenated tallow amine. The polyolefin of the instant compositions is preferably a homopolymer or copolymer of an alpha-olefin. The saturated polyolefins useful in the instant compositions are the polymers derived from monoolefins, such as e.g. polyethylene, which can be crosslinked, polypropylene, polyisobutylene, polybutene-1, poly-3-methylbutene-1 and poly-4-methylpentene-1. Polyethylene may be for example medium density, high density or linear low density polyethylene. Mixtures of the homopolymers cited above, for example mixtures of polypropylene and polyethylene, polypropylene and polybutene-1, or polypropylene and polyisobutylene may also be used. Copolymers of monoolefins may also be used in the instant compositions, for example ethylene/propylene copolymers, propylene/butene-1 copolymers, propylene/octene-1 copolymers, ethylene/butene-1 copolymers, ethylene/octene-1 copolymers as well as ethylene/vinyl acetate copolymers. The instant compositions particularly employ as the polyolefin component polyethylene, polypropylene, polyisobutylene, poly(butene-1), poly(pentene-l), poly(3-methylbutene-1), poly(4-methylpentene-1) and various ethylene and propylene copolymers. Especially preferred polyolefin substrates are polypropylene, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, poly(butene-1), ethylene/vinyl acetate copolymer, ethylene/propylene copolymer and copolymers of ethylene or of propylene with other alpha-olefins. The most preferred polyolefin substrate is polypropylene, high density polyethylene, ethylene/propylene copolymer or a copolymer of ethylene or of propylene with another alpha-olefin, low density polyethylene or linear low density polyethylene. The polyolefins used in the food wrapping industry are of particular interest in these compositions. Hydroxylamines of special interest are those compounds of formula I where T₁ and T₂ are each hexadecyl or T₁ is hexadecyl and T₂ is octadecyl; or where T₁ is hexadecyl and T₂ is heptadecyl or octadecyl; or where T₁ is heptadecyl and T₂ is octadecyl. A typical di(hydrogenated tallow)amine has the following distribution of alkyl substituents: T₁T₂NH T₁ T₂ % C₁₆ C₁₄ 1.9 C₁₆ C₁₆ 12.4 C₁₆ C₁₇ 2.8 C₁₆ C₁₈ 36.0 C₁₇ C₁₈ 3.9 C₁₈ C₁₈ 39.0 other 4.0 It is clear that the di(hydrogenated tallow)amine originating from animal sources may well vary somewhat in the specific distribution of alkyl substituents, but the di(hydrogenated tallow)amine contains major amounts of N,N-dihexadecylamine, N,N-dioctadecylamine and N-hexadecyl-N-octadecylamine. The individual components of the mixture can be separated by distillation under high vacuum. However, for the purposes of this invention, there is no need to carry out such separation and the hydroxylamine prepared from the di(hydrogenated tallow)amine represents a preferred embodiment of the present invention. The instant long chain N,N-dialkylhydroxylamines can be prepared by a number of methods. These include (A) the oxidation of the corresponding secondary amine with aqueous hydrogen peroxide to form the desired N,N-dialkylhydroxylamine directly; (B) the addition of the secondary amine to an alpha,beta-unsaturated compound such as an alkyl acrylate to form a Michael addition product, which is in turn oxidized to the corresponding tertiary amine oxide using aqueous hydrogen peroxide, and followed by the elimination of the alpha,beta-unsaturated compound by the Cope reaction to give the N,N-dialkylhydroxylamine; (C) the metathesis reaction between an alkyl halide and a hydroxylamine in the presence of alkali such as sodamide; and (D) the reaction of an amine with a peroxy compound, such as benzoyl peroxide, followed by saponification of the intermediate formed to the desired hydroxylamine derivative. The intermediates used for these synthetic methods are chiefly items of commerce. The Food and Drug Administration (FDA) requires that any stabilizers or additives used in food packaging resist being extracted or otherwise lost from the packaging material into the food it is supposed to protect. Thus additives which are highly volatile or which can migrate easily or which are extracted by the food from the packaging material are unattractive however efficacious the additive may be as a stabilizer. Extraction studies are often carried out with heptane and with 50 % aqueous ethanol which simulate the kinds of food often used in packaged food. While higher molecular weight materials are generally less volatile and less soluble in solvents, the instant long chain N,N-dialkylhydroxylamines of formula I show unexpected superiority in resisting extraction using 50 % aqueous ethanol from a polypropylene plaque compared to the lower chain N,N-dialkylhydroxylamines of the prior art. It is found that the instant long chain N,N-dialkylhydroxylamines are excellent process stabilizers for polyolefins when used alone in the absence of any phenolic antioxidant or even in the absence of any calcium stearate or other alkaline metal salt of a fatty acid. In general, the hydroxylamine stabilizers of formula I and II are employed from 0.01 to 5 % by weight of the stabilized composition although this will vary with the particular substrate and application. An advantageous range is from 0.025 to 2 %, and especially 0.05 to 1 %. The hydroxylamines of this invention stabilize polyolefins especially during high temperature processing with relatively little change in color and melt flow values even though the polymer may undergo a number of extrusions. The stabilized polyolefin compositions of the instant invention may also contain a stabilizer or mixture of stabilizers selected from the group consisting of the alkaline metal salts of fatty acids, the phenolic antioxidants, the hindered amine light stabilizers, the ultraviolet light absorbers, the organic phosphorus compounds and the thiosynergists. Additionally, it is found that the instant long chain N,N-dialkylhydroxylamines are excellent process stabilizers for polyolefins when used in the presence of (c) an alkaline metal salt of a fatty acid or mixture thereof and in the absence of any other stabilizer. The alkaline metal salts of a fatty acid useful in the instant compositions are the alkali metal, alkaline earth metal, zinc, cadmium or aluminum salts of the higher fatty acids, for example calcium stearate, zinc stearate, magnesium behenate, sodium ricinoleate or potassium palmitate. Calcium stearate or zinc stearate are particularly preferred. The instant compositions may contain from 0.01 to 2 % of the alkaline metal salt of a fatty acid, preferably 0.05 to 1 %, and especially 0.1 to 0.5 % by weight of the stabilized composition. Another embodiment of the instant invention pertains to the instant compositions which additionally contain both (c) an alkaline metal salt of a fatty acid or mixture thereof, and (d) a phenolic antioxidant or mixture thereof. Still another embodiment of the instant invention pertains to the instant compositions which additionally contain (e) a hindered amine light stabilizer or mixture thereof. Another embodiment of the instant invention relates to the instant compositions which additionally contain (f) an organic phosphorus compound or mixture thereof. Still another embodiment of the instant invention involves the instant compositions which additionally contain (c) an alkaline metal salt of a fatty acid or mixture thereof, and (e) a hindered amine light stabilizer or mixture thereof. Another embodiment of the instant invention pertains to the instant compositions which additionally contain (c) an alkaline metal salt of a fatty acid or mixture thereof, (d) a phenolic antioxidant or mixture thereof, and (e) a hindered amine light stabilizer or mixture thereof. Another embodiment of the instant invention involves the instant compositions which additionally contain (c) an alkaline metal salt of a fatty acid or mixture thereof, (d) a phenolic antioxidant or mixture thereof, and (f) an organic phosphorus compound or mixture thereof. Another embodiment of the instant invention pertains to the instant compositions which additionally contain (c) an alkaline metal salt of a fatty acid or mixture thereof and (f) an organic phosphorus compound or mixture thereof. Still another embodiment of the instant invention involves the instant compositions which additionally contain (e) a hindered amine light stabilizer or mixture thereof, and (f) an organic phosphorus compound or mixture thereof. Another embodiment of the instant invention pertains to the instant compositions which additionally contain (c) an alkaline metal salt of a fatty acid or mixture thereof, (e) a hindered amine light stabilizer or mixture thereof, and (f) an organic phosphorus compound or mixture thereof. Still another embodiment of the instant invention relates to the instant compositions which additionally contain (c) an alkaline metal salt of a fatty acid or mixture thereof, (d) a phenolic antioxidant or mixture thereof, (e) a hindered amine light stabilizer or mixture thereof, and (f) an organic phosphorus compound or mixture thereof. Another embodiment of the instant invention involves the instant compositions which additionally contain (d) a phenolic antioxidant or mixture thereof. The preferred long chain N,N-dialkylhydroxylamines of formula I and II used in these embodiments of the instant invention as well as the preferred alkaline metal salts of the fatty acids are described above. The preferred phenolic antioxidants, hindered amine light stabilizers, ultraviolet light absorbers, organic phosphorus compounds and thiosynergists are set forth below. The phenolic antioxidants useful in the instant compositions embrace a large family of compounds examples of which are: Simple 2,6-dialkylphenols, such as, for example, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, 2,6-dioctadecyl-4-methylphenol and 2,6-di-tertbutylphenol. Derivatives of alkylated hydroquinones, such as, for example, 2,5-di-tert-butyl-hydroquinone, 2,5-di-tert-amyl-hydroquinone, 2,6-di-tert-butyl-hydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, tris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite, 3,5-di-tert-butyl-4-hydroxyphenyl stearate and bis(3,5-di-tert-butyl-4-hydroxyphenyl)adipate. Hydroxylated thiodiphenyl ethers, such as, for example, 2,2'-thio-bis-(6-tert-butyl-4-methylphenol), 2,2'-thio-bis(4-octylphenol), 4,4'-thio-bis(6-tert-butyl-3-methylphenol), 4,4'-thio-bis(3,6-di-sec-amylphenol), 4,4'-thio-bis(6-tert-butyl-2-methylphenol) and 4,4'-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide. Alkylidene-bisphenols, such as, for example, 2,2'-methylene-bis(6-tert-butyl-4-methylphenol), 2,2'-methylene-bis(6-tert-butyl-4-ethylphenol), 4,4'-methylene-bis(6-tert-butyl-2-methylphenol), 4,4'-methylene-bis(2,6-di-tert-butylphenol), 2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)4-methylphenol, 2,2'-methylene-bis[4-methyl-6-(alpha-methylcyclohexyl)-phenol], 1,1-bis(3,5-dimethyl-2-hydroxyphenyl)butane, 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)propane, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)-butane, 2,2-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecyl-mercaptobutane, 1,1,5,5-tetrakis(5-tert-butyl-4-hydroxy-2-methylphenyl)-pentane and ethylene bis([3,3-bis(3-tert-butyl-4-hydroxyphenyl)-butyrate]. O-, N- and S-benzyl compounds, such as, for example, 3,5,3',5'-tetra-tert-butyl-4,4'-dihydroxydibenzyl ether, octadecyl 4-hydroxy-3,5-dimethylbenzyl-mercaptoacetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)-amine and bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate. Hydroxybenzylated malonates, such as, for example, dioctadecyl 2,2-bis-(3,5-di-tert-butyl-2-hydroxybenzyl)malonate, dioctadecyl 2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)malonate, bis(dodecylmercapto)ethyl 2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate and bis[4-(1,1,3,3-tetramethylbutyl)phenyl] 2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-malonate. Hydroxybenzyl-aromatic compounds, such as, for example, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene and 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.(3,5-di-tert-butyl-4-hydroxybenzyl)phenol. s-Triazine compounds, such as, for example, 2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hydroxyanilino)-s-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-s-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-s-triazine, 2,4,6-tris-(3,5-di-tert-butyl-4-hydroxyphenoxy)-s-triazine, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-s-triazine, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate. Amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, such as, for example, 1,3,5-tris[(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]-hexahydro-s-triazine and N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenyl-propionyl)hexamethylenediamine, N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine. Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionicacid with monohydric or polyhydric alcohols, such as, for example, with methanol, ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, diethylene glycol, thiodiethylene glycol, triethylene glycol, neopentylglycol, pentaerythritol, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolethane, trimethylolpropane, tris[hydroxyethyl]isocyanurate and 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with monohydric or polyhydric alcohols, such as, for example, with methanol, ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, diethylene glycol, triethylene glycol, thiodiethylene glycol, neopentylglycol, pentaerythritol, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolethane, trimethylolpropane, tris[hydroxyethyl]isocyanurate and 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. Esters of 3,5-di-tert-butyl-4-hydroxyphenylacetic acid with monohydric or polyhydric alcohols, such as, for example, with methanol, ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propenediol, diethylene glycol, thiodiethylene glycol, neopentylglycol, pentaerythritol, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolethane, trimethylolpropane, tris[hydroxyethyl]isocyanurate and 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]-octane, especially the tetrakis ester of pentaerythritol. Benzylphosphonates, such as, for example, dimethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl tert-butyl-4-hydroxy-3-methylbenzylphosphonate, and calcium bis(0-ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate). The phenolic antioxidants of particular interest are n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), di-n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 1,3,5-tris(3,5-di-tert-butyl-4-hydro, benzyl)isocyanurate, thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 3,6-dioxaoctamethylene bis(3-methyl-5-tert-butyl-4hydroxyhydrocinnamate), 2,6-di-tert-butyl-p-cresol, 2,2'-ethylidene-bis-(4,6-di-tert-butylphenol), 1,3,5-tris(2,6-dimethyl-4-tert-butyl-3-hydroxybenzyl)isocyanurate, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butyl-phenyl)butane, 1,3,5-tris[2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)ethyl]isocyanurate, 3,5-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-mesitol, hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1-(3,5-di-tert-butyl-4-hydroxyanilino)-3,5-bis(octylthio)-s-triazine, N,N'-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide), calcium bis(ethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate), ethylene bis(3,3-bis(3-tert-butyl-4-hydroxyphenyl)butyrate], octyl 3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate, bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazide, N,N'-bis[2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)ethyl]oxamide, and 3,6-dioxaoctamethylene-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate). A most preferred phenolic antioxidant is neopentanetetrayl tetrakis-(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 2,6-di-tert-butyl-p-cresol, 2,2'-ethylidene-bis-(4,6-di-tert-butylphenol) or calcium bis(0-ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate). When the instant compositions contain a hindered amine light stabilizer, such hindered amines may be for example 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, bis(2,2,6,6-tetramethylpiperidyl)sebacate or 3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triaza-spiro[4.5]decane-2,4-dione. The hindered amine light stabilizer of particular interest is selected from the group consisting of bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate, bis(1,2,2,6,6-pentamethylpiperidin-4-yl)sebacate, bis-(1,2,2,6,6-pentamethylpiperidin-4-yl)(3,5-di-tert-butyl-4-hydroxybenzyl)butylmalonate, tris(2,2,6,6-tetramethylpiperidin-4-yl)nitrilo-triacetate, 1,2-bis(2,2,6,6-tetramethyl-3-oxopiperazin-4-yl)ethane, 2,2,4,4-tetramethyl-7-oxa-3,20-diaza-2l-oxodispiro[5.1.11.2]heneicosane, polycondensation product of 2,4-dichloro-6-tert-octylamino-s-triazine and 4,4'-hexamethylene-bis(amino-2,2,6,6-tetramethylpiperidine), polycondensation product of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, polycondensation product of 4,4'-hexamethylene-bis(amino-2,2,6,6-tetramethylpiperidine) and 1,2-dibromoethane, polycondensation product of 2,4-dichloro-6-morpholino-s-triazine and 4,4'-hexamethylene-bis(amino-2,2,6,6-tetramethylpiperidine), N,N',N',N"'-tetrakis[4,6-bis(butyl-(2,2,6,6-tetramethylpiperidin-4-yl)-amino)-s-triazin-2-yl]-1,10-diamino-4,7-diazadecane, octamethylene bis(2,2,6,6-tetramethylpiperidin-4-carboxylate) and 4,4'-ethylene-bis-(2,2,6,6-tetramethylpiperazin-3-one).(2,2,6,6-tetramethylpiperazin-3-one). A most preferred hindered amine light stabilizer is bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate, the polycondensation product of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the polycondensation product of 2,4-dichloro-6-tert-octylamino-s-triazine and 4,4'-hexamethylene-bis(amino-2,2,6,6-tetramethylpiperidine) or N,N',Y",Y"'-tetrakis[4,6-bis(butyl-(2,2,6,6-tetramethylpiperidin-4-yl)-amino)-s-triazin-2-yl]-1,10-diamino-4,7-diazadecane. When the instant compositions contain an ultraviolet light absorber, such light absorbers may include the 2H-benzotriazoles, the benzophenones, the oxanilides, the alpha-cyanocinnamates, the substituted benzoate esters or the nickel salts of the 0-alkyl hindered phenolic benzylphosphonates. Examples of such ultraviolet light absorbers are seen below: 2-(2'-Hydroxyphenyl)benzotriazoles, e.g., the 5'-methyl-, 3',5'-di-tert-butyl-, 5'-tert-butyl-, 5'-(1,1,3,3-tetramethylbutyl)-, 5-chloro-3',5'-di-tert-butyl-, 5-chloro-3'-tert-butyl-5'-methyl-, 3'-sec-butyl-5'-tert-butyl-, 3'-alpha-methyl-benzyl-5'-methyl-, 3'-alpha-methyl-benzyl-5'-methyl-5-chloro-, 4'-hydroxy-, 4'-methoxy-, 4'-octyloxy-, 3',5'-di-tert-amyl-, 3'-methyl-5'-carbomethoxyethyl- and 5-chloro-3',5'-di-tert-amyl-derivative. 2,4-Bis(2'-hydroxyphenyl)-6-alkyl-s-triazines, e.g., the 6-ethyl-, 6-heptadecyl- or 6-undecyl-derivative. 2-Hydroxybenzophenones, e.g., the 4-hydroxy-, 4-methoxy-, 4-octyloxy-, 4-decyloxy-, 4-dodecyloxy-, 4-benzyloxy-, 4,2',4'-trihydroxy-, 2,2',4,4'-tetrahydroxy- or 2'-hydroxy-4,4'-dimethoxy-derivative. 1,3-Bis(2'-hydroxybenzoyl)benzenes, e.g., 1,3-bis(2'-hydroxy-4'-hexyloxybenzoyl)benzene, 1,3-bis(2'-hydroxy-4'-octyloxybenzoyl)benzene or 1,3-bis(2'-hydroxy-4'-dodecyloxybenzoyl)benzene. Esters of optionally substituted benzoic acids, e.g., phenyl salicylate, octylphenyl salicylate, dibenzoylresorcin, bis(4-tert-butylbenzoyl)-resorcin, benzoylresorcin, 3,5-di-tert-butyl-4-hydroxybenzoic acid 2,4-di-tert-butylphenyl ester or 2-octadecyl ester or 2-methyl-4,6-di-tert-butyl ester. Acrylates, e.g., alpha-cyano-β,β-diphenylacrylic acid-ethyl ester or isooctyl ester, alpha-carbomethoxy-cinnamic acid methyl ester, alpha-cyano-β-methyl-p-methoxy-cinnamic acid methyl ester or butyl ester or N-(β-carbomethoxyvinyl)-2-methyl-indoline. Oxalic acid diamides, e.g., 4,4'-dioctyloxy-oxanilide, 2,2'-dioctyloxy-5,5'-di-tert-butyloxanilide, 2,2'-didodecyloxy-5,5'-di-tert-butyloxanilide, 2-ethoxy-2'-ethyl-oxanilide, N,N'-bis(3-dimethylaminopropyl)-oxalamide, 2-ethoxy-5-tert-butyl-2'-ethyloxanilide and the mixture thereof with 2-ethoxy-2'-ethyl-5,4'-di-tert-butyl-oxanilide, or mixtures of ortho- and para-methoxy- as well as of o- and p-ethoxy-disubstituted oxanilides. Preferably the ultraviolet light absorber useful in the instant compositions is 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole, 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole, 2-[2-hydroxy-3,5-bis-(alpha,alpha-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole, 2-hydroxy-4-octyloxy-benzophenone, nickel bis(0-ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate), 2,4-dihydroxybenzophenone, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzotriazole, nickel butylamine complex with 2,2'-thiobis(4-tert-butylphenol), 2-ethoxy-2'-ethyloxanilide or 2-ethoxy-2'-ethyl-5,5'-di-tert-butyloxanilide. When the instant compositions contain an organic phosphorus compound, such compounds may be, for example, triphenyl phosphite, diphenylalkyl phosphites, phenyldialkyl phosphites, tris(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, 3,9-bis(isodecyloxy)-2,4,8,10-tetraoxa-3,9-diphospha[5.5]undecane and tris(4-hydroxy-3,5-di-tert-butylphenyl)phosphite or similar phosphonites. The organic phosphorus compound of particular interest is selected from the group consisting of tris(2,4-di-tert-butylphenyl)phosphite, 3,9-bis-(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphospha[5.5]undecane, tris(p-nonylphenyl)phosphite, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphospha[5.5]undecane, 3,9-distearyloxy-2,4,8,10-tetraoxa-3,9-diphospha[5.5]undecane, dilauryl phosphite, 3,9-bis[2,6-di-tert-butyl-4-(2-(n-octadecyloxycarbonyl)ethyl)phenoxy]-2,4,8,10-tetraoxa-3,9-diphospha[5.5]undecane and tetrakis(2,4-di-tert-butylphenyl)-4,4'-bis[diphenylene phosphonite]. Tris(2,4-di-tert-butylphenyl)phosphite is especially preferred. When the instant compositions contain a thiosynergist, such thiosynergists may be for example dilauryl thiodipropionate, distearyl thiodipropionate or neopentanetetrayl tetrakis(3-dodecylthiopropionate). Distearyl thiodipropionate or dilauryl thiodipropionate is particularly preferred. The following may be mentioned as examples of further additives that can be used in the instant compositions. Metal deactivators, e.g., oxanilide, isophthalic acid dihydrazide, sebacic acid bis[phenylhydrazide], bis-benzylidene-oxalic acid hydrazide, N,N'-diacetal adipic acid dihydrazide, N,N'-bis(salicyloyl)oxalic acid dihydrazide, N,N'-bis(salicyloyl)hydrazine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine, N-salicyloyl-N'-salicylalhydrazine, 3-salicyloyl-amino-1,2,4-triazole or N,N'-bis(salicyloyl)thiopropionic acid dihydrazide. Nucleation agents, e,g., 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid or substituted sorbitols such as 1,3,2,4-dibenzylidene-sorbitol. Other additives that can be incorporated in the stabilized compositions are antiblocking agents, clarifiers, antiozonants, lubricants such as e.g. stearyl alcohol, fillers, carbon black, asbestos, kaolin, talc, glass fibers, pigments, colorants, dyes, optical brighteners, flameproofing agents and antistatic agents. The stabilizers may be readily incorporated into the polyolefins by conventional techniques at any convenient stage prior to the manufacture of shaped articles therefrom. For example, the stabilizers may be mixed with the polymer in dry powder form, or a suspension or emulsion of the stabilizer may be mixed with a solution, suspension or emulsion of the polymer. If the stabilized polyolefin compositions contain conventional additives such as the materials listed above, e.g. phenolic antioxidants, hindered amine light stabilizers, ultraviolet light absorbers, organic phosphorus compounds and thiosynergists, these additives may be present in a concentration of e.g. about 0.01 to about 5 %, preferably about 0.025 to about 2 %, and especially about 0.1 to about 1 %, by weight of the stabilized composition. It is also possible to apply the instant stabilizers by a topical application to the finished articles. This is particularly useful with fiber applications where the instant stabilizers are applied topically to the fibers, for example, by way of a spin finish during the melt spinning process. Example 1: Preparation of Methyl-3-[di(hydrogenated tallow)amino]-propionate A mixture of 49.4 g (0.1 mol) of di(hydrogenated tallow)amine (eq. wt. of 494 g/mol) and 9 ml (0.1 mol) of methyl acrylate are heated to reflux. Upon completion of the addition reaction, as determined by the complete disappearance of the starting amine by thin layer chromatography (TLC) analysis, the mixture is cooled. The volatiles are removed in vacuo to give 54.4 g (94 % yield) of the above-named product as a yellow oil. IR (methylene chloride) v c=o 1735 cm⁻¹. Analysis: Calcd for C₃₈H₇₇NO₂: C, 78.7; H, 13.4; N, 2.4. Found: C, 78.8; H, 13.4; N, 2.4. Example 2: Preparation of N,N-Di(hydrogenated tallow)hydroxylamine Into a solution of 29 g (0.05 mol) of the product of Example 1 in 200 ml of isopropanol is added 2.4 ml (0.063 mol) of 70 % aqueous hydrogen peroxide solution. After stirring at 23-25°C for 1 hour, an additional 1.2 ml (0.031 mol) of a 70 % aqueous hydrogen peroxide solution is added. After stirring for another 1 hour at 23-25°C, another additional 1.2 ml (0.031 mol) of 70 % aqueous hydrogen peroxide is added. After a total of 18 hours stirring at 23-25°C, the product is isolated by filtration and washed with isopropanol to give 20.9 g (82 % yield) of white solid melting at 88-90°C. The product (19 g) is recrystallized from 300 ml of isopropanol to give 13.1 g (69 % recovery) of the above-named product as a white solid melting at 93-95°C. Analysis: Calcd for C₃₄H₇₁NO: C, 80.1; H, 14.0; N, 2.8. Found: C, 80.0; H, 14.3; N, 2.9. Example 3: Preparation of 2-Ethylhexyl-3-[di(hydrogenated tallow)amino]-propionate Following the general procedure of Example 1, 52.2 g (0.105 mol) of di(hydrogenated tallow)amine (eq. wt. of 494 g/mol) and 18.4 g (0.1 mol) of 2-ethylhexyl acrylate are reacted. The reaction product is purified by high pressure liquid chromatography (HPLC) using hexane and ethyl acetate solvents on silica gel to give 40.6 g (60 % yield) of the above-named product as a colorless oil. IR (methylene chloride) v c=o 1735 cm⁻¹. Example 4: Preparation of N,N-Di(hydrogenated tallow)hydroxylamine Using the general procedure of Example 2, 29.7 g (0.044 mol) of the product of Example 3 in 125 ml of isopropanol is oxidized using 2.5 ml (0.065 mol) of 70 % aqueous hydrogen peroxide to yield 16.3 g (73 % yield) of the above-named product as a white solid melting at 93-96°C. From the HPLC purification, using hexane and ethyl acetate solvents, of the filtrate, 4.4 g (48 % yield) of 2-ethylhexyl acrylate is recovered. Example 5 not part of the invention: Preparation of Methyl-3-(didodecylamino)propionate Following the general procedure of Example 1, 75 g (0.21 mol) of didodecylamine and 19.1 ml (0.21 mol) of methyl acrylate are reacted to give 92.6 g (quantitative yield) of the above-named product as a yellow oil. This oil (5.0 g) is purified by column chromatography using hexane and ethyl acetate solvents on silica gel to give 4.9 g (98 % recovery) of a colorless oil. Analysis: Calcd for C₂₈H₅₇NO₂: C, 76.5; H, 13.1; N, 3.2. Found: C, 76.6; H, 13.0; N, 3.1. Example 6 not part of the invention: Preparation of N,N-Didodecylhydroxylamine Using the general procedure of Example 2, 87.6 g (0.2 mol) of the product of Example 5 in 800 ml of isopropanol is oxidized using 9.7 ml (0.25 mol) of 70 % aqueous hydrogen peroxide solution to give 32.1 g (44 % yield) of the above-named product as a white solid melting at 85-86°C. Analysis: Calcd for C₂₄H₅₁NO: C, 78.0; H, 13.9; N, 3.8. Found: C, 78.4; H, 13.5; N, 3.7. Example 7 not part of the invention: Preparation of Methyl-3-(ditetradecylamino)propionate Following the general procedure of Example 1, 50.4 g (0.123 mol) of ditetradecylamine and 11.1 ml (0.123 mol) of methyl acrylate are reacted to give 62.6 g (quantitative yield) of the above-named product as a yellow oil. This oil (5.0 g) is purified by column chromatography using hexane and ethyl acetate solvents on silica gel to give 4.9 g of a colorless oil. Analysis: Calcd for C₃₂H₆₅NO₂: C, 77.5; H, 13.2; N, 2.8. Found: C, 77.8; H, 13.4; N, 3.0. Example 8 not part of the invention: Preparation of N,N-Ditetradecylhydroxylamine Using the general procedure of Example 2, 57.5 g (0.116 mol) of the product of Example 7 in 450 ml of isopropanol is oxidized using 5.6 m (0.15 mol) of 70 % aqueous hydrogen peroxide solution to give 21.5 g (44 % yield) of the above-named product as a white solid melting at 94-96°C. Analysis: Calcd for C₂₈H₅₉NO: C, 79.0; H, 14.0; N, 3.3. Found: C, 79.2; H, 14.0; N, 3.2. Example 9: Preparation of N,N-Di(hydrogenated tallow)hydroxylamine Into a solution of 100 g (0.18 mol) of di(hydrogenated tallow)amine (494 eq. wt., 90 % secondary amine) in 400 ml of n-butanol at 55°C is added 8.6 ml (0.22 mol) of 70 % aqueous hydrogen peroxide solution. The reaction is complete when all the hydrogen peroxide is consumed as determined by titration of an aliquot of the reaction mixture with potassium iodide/sulfuric acid/sodium thiosulfate. The above-named product is isolated from the reaction mixture by filtration. The filter cake is washed with two 50 ml portions of n-butanol at 55°C; then dried to give the desired product in a yield of 63 g (68 %) as a white solid melting at 93-96°C. Example 10 : Preparation of N,N-Di(hydrogenated tallow) hydroxylamine Following the general procedure of Example 9, to a solution of 52.6 g (0.09 mol) of di(hydrogenated tallow)amine (526 eq. wt., 90 % secondary amine) dissolved in 200 ml of n-butanol at 55°C is added 5.3 ml (0.14 mol) of 70 % aqueous hydrogen peroxide solution. During the course of the reaction three additional 0.5 ml (0.01 mol) portions of 70 % aqueous hydrogen peroxide solution are added after 22, 24 and 72 hours. The progress of the reaction is followed by thin layer chromatography (TLC) (silica gel; chloroform/acetic acid 98/2). The reaction is complete when all the starting amine has disappeared as determined by the TLC analysis. The above-named product is isolated from the reaction mixture by filtration. The filter cake is washed with 100 ml of n-butanol at 55°C, and then with two 200 ml portions of methanol at ambient temperature to give the desired product in a yield of 27.6 g (57 %) as a white solid melting at 98-100°C. Example 11 : Preparation of N,N-Di(hydrogenated tallow)hydroxylamine Following the general procedure of Example 9, to 200 g (0.36 mol) of di(hydrogenated tallow)amine (494 eq. wt., 90 % secondary amine) suspended in 800 ml of ethanol at 55°C is added 29.4 ml (0.77 mol) of 70 % aqueous hydrogen peroxide solution. After stirring for 18 hours at 55°C, the reaction mixture is filtered and the moist filter cake is recrystallized from 1000 ml of hexane. The recrystallized material is washed with 500 ml of hexane at 55°C. The above-named product is obtained in a yield of 123 g (66 %) as a white solid melting at 90-93°C. Example 12 : Preparation of N,N-Dihexadecylhydroxylamine The general procedure of Example 11 is followed using 100 g (0.19 mol) of dihexadecylamine (451 eq. wt., 88 % secondary amine, 30.2 g (0.44 mol) of 50 % aqueous hydrogen peroxide solution and 400 ml of ethanol. After stirring for 48 hours, the reaction mixture is filtered to give the above-named product which is twice recrystallized from 500 ml of chloroform. The desired product is obtained in a yield of 29.4 g (32 %) as white needles melting at 97-99°C. Analysis: Calcd for C₃₂H₆₇NO: C, 79.8; H, 14.0; N, 2.0. Found: C, 79.5; H, 14.0; N, 2.7. Example 13 not of the invention: Preparation of N,N-Didodecylhydroxylamine Following the general procedure of Example 12, to a solution of 50 g (0.14 mol) of didodecylamine dissolved in 200 ml of n-propanol at 40°C is added dropwise 9.62 g (0.14 mol) of 50 % aqueous hydrogen peroxide solution. After 72 hours at 40-45°C, the reaction mixture is filtered to give a crude product which is subsequently recrystallized from 300 ml of hexane. The above-named product is obtained in a yield of 24.8 g (48 %) as white needles melting at 90-92°C. Analysis: Calcd for C₂₄H₅₁NO: C, 78.0; H, 13.9; N, 3.8. Found: C, 78.0; H, 14.2; N, 3.7. Example 14 not of the invention: Preparation of N,N-Ditetradecylhydroxylamine The general procedure of Example 12 is followed using at 50 to 55°C 50 g (0.12 mol) of ditetradecylamine, 200 ml of n-propanol and 8.3 g (0.12 mol) of 50 % aqueous hydrogen peroxide solution. The above-named product is obtained in a yield of 33.4 (64 %) as white needles melting at 97-99°C. Example 15: Preparation of N,N-Di(hydrogenated tallow)hydroxylamine To a suspension of 68 g of anhydrous dibasic sodium phosphate and 25 g of di(hydrogenated tallow)amine in 200 ml of dry tetrahydrofuran is added a solution of 12.8 g of benzoyl peroxide in 100 ml of tetrahydrofuran over a 30-minute period. The resulting suspension is heated under reflux for 14 hours and then cooled to room temperature. The insoluble present is removed by filtration and the filtrate is concentrated under reduced pressure to give 35 g of a pale yellow solid. Saponification of 12 g of the benzoate prepared above with 1.89 g of potassium hydroxide in 50 ml of tetrahydrofuran and 40 ml of methanol affords the compound mixture named in the title. Recrystallization of the crude material form isopropanol gives 7 g of the titel compound as a white solid melting at 95-97°C. Analysis: Calcd for C₃₄H₇₁NO: C, 80.1; H, 14.0; N, 2.8. Found: C, 80.2, H, 13.9; N, 2.7. Example 16: Process Stabilization of Polypropylene at 260°C The base formulation comprises 100 parts of unstabilized polypropylene (®Profax 6501, Himont) with 0.10 parts of calcium stearate. N,N-DI-(hydrogenated tallow)hydroxylamine is solvent blended onto the propylene from a solution in methylene chloride. After removal of the solvent by evaporation under reduced pressure, the stabilized resin formulation is extruded at 100 rpm from a 2.54 cm diameter extruder at 260°C. After each of the first, third and fifth extrusions, resin pellets are compression molded into 3.2 mm thick plaques at 193°C and specimen yellowness index (YI) is determined according to ASTM D-1925. Low YI values indicate less yellowing. Additionally, the melt flow rate (in g/10 minutes) according to ASTM D-1238 is measured on the pellets after the first extrusion is to the melt flow rate after extrusion indicates superior process stabilization of the polypropylene. % by weight of N,N-Di-(hydrogenated tallow)hydroxylamine Yellowness Index Color After Extrusion Melt Flow Rate After Extrusion 1 3 5 1 5 - 3.3 3.1 3.5 5.3 29.3 0.025 2.4 2.8 3.3 2.2 4.4 Example 17 : Process Stabilization of Polypropylene at 288°C Following the general procedure described in Example 16, polypropylene (®Spheripol 6301, Himont) containing 0.1 % by weight of calcium stearate is extruded at 288°C with N,N-di(hydrogenated tallow)hydroxylamine. The yellowness index values and melt flow rate values are determined as described in Example 16 to ascertain the efficacy of each stabilizer in protecting the polymer during this high temperature processing. % by weight of N,N-Di-(hydrogenated tallow)hydroxylamine Yellowness Index Color After Extrusion Melt Flow Rate After Extrusion 1 3 5 1 5 - 4.6 8.6 10.6 20.8 83.2 0.025 1.0 1.7 2.1 15.0 26.3 0.05 1.5 2.0 2.6 13.1 21.4 0.1 1.1 2.3 3.1 12.4 17.2 Example 18 : Process Stabilization of Polypropylene at 260°C Following the general procedure described in Example 16 polypropylene (®Profax 6301, Himont) containing 0.1 % by weight of calcium stearate plus various hydroxylamines is converted into pellets by extrusion at 260°C and separately spun at 260°C into filament (10-11 dtex) form. The melt flow rate is determined for the pellets and for the corresponding fibers. Example 19 : Process Stabilization of Polypropylene at 260°C Following the general procedure of Example 16, another polypropylene (®El Paso PP) containing 0.1 % of zinc stearate is stabilized with N,N-di(hydrogenated tallow)hydroxylamine. The effectiveness of the hydroxylamine is measured by the determination of melt flow rate values on the test samples after extrusions at 260°C. % by weight of N,N-Di(hydrogenated tallow)hydroxylamine Melt Flow Rate After Extrusion 1 5 - 5.9 10.0 0.05 3.4 5.0 0.1 3.5 4.7 Example 20 : Extraction of Polypropylene Plaques with 50 % Ethanol Propylene (®Profax 6501, Himont) containing 0.1 % by weight of calcium stearate, 0.033 % by weight of neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 0.067 % by weight of tris(2,4-di-tert-butylphenyl) phosphite and 0.25 % by weight of a N,N-dialkylhydroxylamine test compound is extruded at 260°C. The extruded composition is then compression molded at 227°C into a plaque having the dimensions of 2.54 cm x 5.08 cm x 0.77 mm and containing 1 g of polypropylene. The test plaques are extracted with 50 ml of 50 % aqueous ethanol at 49°C for 10 days after being exposed for an initial period of 2 hours in said solvent at 66°C. These extraction conditions conform to those required by the FDA in assessing the acceptability of additives for use in food packaging. The concentration of the test additive in the plaques is determined using chemiluminescence based on nitrogen content. The sample plaques are analyzed by combusting a 200 mg sample in the furnace of an Antek chemiluminescence nitrogen analyzer with a programmed combustion from 120°C to 700°C. The plaques are analyzed before and then after extraction with the 50 % aqueous ethanol. A polypropylene plaque containing no nitrogen containing hydroxylamine additive is used as a blank. Analyses are done in quadruplicate with the average values reported in the table below. Extractability of N,N-Dialkylhydroxylamines from Polypropylene into 50 % Aqueous Ethanol These values are based on nitrogen concentrations after correcting for the nitrogen content of the blank. Example 21 : Process Stabilization of Polypropylene at 260°C Following the general procedure given in Example 16, the efficacy of the instant long chain N,N-dialkylhydroxylamines in providing process stabilization to polypropylene in the absence of all other stabilizer additives is ascertained. To unstabilized polypropylene (®Profax 6501, Himont), containing no other stabilizer additives, is added the various test stabilizers as seen on the table below. Yellowness index (YI) and melt flow rate (MFR) values are obtained to indicate the level of process stabilization afforded by said stabilizers. AO F is neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate). HA 5 is N,N-di(hydrogenated tallow)hydroxylamine. Example 22 : Following the general procedure of Example 18, fiber grade polypropylene containing 0.1 % by weight of calcium stearate is compounded for 1.5 minutes at 220°C to incorporate the test stabilizers listed below. The compounded polymer is then spun at 270°C with a 3-minute residence time for the polymer in the spinning apparatus into a fiber tow of 37 filaments. The spun tow is stretched at a ratio of 1:3.2 to give a final tow with a dezitex of 144. The fibers are exposed in a Xenotest 1200 (Fa. Heraeus) xenon arc weatherometer. The exposure time needed for the initial tensile strength of the fiber tow to fall to half it original value is the criterion used to assess failure in this test. Example 23: Following the general procedure of Examples 18 and 22, the effect of the presence of an instant hydroxylamine and a phenolic antioxidant on enhancing the oxidative stability of polypropylene subjected to oven aging at 120°C, is seen in the table below. The stabilized composition always contains 0.1 % by weight of calcium stearate. The polypropylene compounded as described in Example 22 is molded at 230°C for 3 minutes to give plaques of 1 mm thickness. From these plaques strips (10 mm x 130 mm) are cut which are aged in an air circulating oven at 120°C. The test specimens are considered to have failed (embrittled) when they break when bended with a bending radius of 5 mm. The time in days to reach this embrittlement is recorded in the table below. Example 24: Following the general procedure of Examples 18, 22 and 23, fiber grade polypropylene containing 0.1 % by weight of calcium stearate and 0.011 % of n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate is compounded with the various test stabilizers. A portion of the compounded polymer is directly molded at 230°C for 3 minutes to give plaques of 1 mm thickness. Another portion of the compounded polymer is first spun at 270°C into fibers. The fibers are then converted into plaques of 1 mm thickness. From these plaques, specimen strips are cut which are aged in an air circulating oven at 149°C. The test specimens are considered to be brittle when they break when bended with a radius of 5 mm. The time in days to reach this embrittlement is recorded in the table below. In respect to oven aging protection the combination of hindered amine stabilizer with an instant hydroxylamine greatly enhances the time till failure (embrittlement) occurs. The enhancement is particularly observed when the polypropylene composition is subjected to severe shear forces at high temperature as they occur in fiber spinning and injection molding. Example 25: Process Stabilization of Polypropylene at 260°C Following the procedure of Example 16, unstabilized polypropylene (®Profax 6501, Himont) containing 0.1 % by weight of calcium stearate is extruded at 260°C with various test stabilizers and the specimen yellowness index (YI) and melt flow rate are determined to measure the efficacy of the stabilizers being tested. The results are given below. Example 26: Following the general procedure of Example 16, polypropylene (®Profax 6501, Himont) containing 0.1 % by weight of calcium stearate and 0.05 % by weight of neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate) and the additional test additives indicated in the table below is extruded into pellets. The pellets are pressed at 240°C for 6 minutes to prepare the 1 mm test plaques. The test plaques are then examined for color by the Yellowness Index (YI) method (ASTM D 1925) before aging or exposure to hot water. Separate plaques are exposed to oven aging for 21 days at 120°C or at 135°C; or to exposure in water at 90°C for 7, 14, 21, 28 or 35 days. Yellowness index values are obtained on each plaque after said exposure. The YI values are recorded in the table below. Low YI values indicate less yellowing or discoloration. Run A B C D Extrusion Temp. °C 280 280 260 260 % by wt.of tris(2,4-di-tert-butylphenyl)phosphite 0.05 0.025 - - % by wt. of N,N-di(hydrogenated tallow)hydroxylamine 0.05 0.025 0.1 0.05 Yellowness Index Values Before aging 0.8 1.1 0.8 0.7 After exposure in water at 90°C for 7 days 2.9 1.8 1.9 2.1 14 days 2.6 2.3 3.3 2.8 After oven aging for 21 days at 120°C 5.8 5.4 4.9 5.8 at 135°C 9.6 9.5 10.9 10.3 Example 27: Following the general procedure of Example 16, polypropylene (®Propathene HF 26, ICI) containing 0.1 % by weight of calcium stearate and containing various test additives indicated in the table below is extruded at 260°C. Melt flow rates and yellowness index values are measured after the 1st, 3rd and 5th extrusions to ascertain the effectiveness of the stabilizers present. Example 28: Following the general procedure of Example 16, polypropylene (®Spheripol, Himont) containing 0.1 % by weight of calcium stearate and the additional stabilizers listed in the table below is extruded at 260°C or at 280°C. The melt flow rate and yellowness index values are measured after the 1st, 3rd and 5th extrusions to assess the efficacy of the stabilizers present in the test sample. Extrusion at 260°C: Stabilizer Yellowness Index Color After Extrusion Melt Flow Rate After Extrusion 1 3 5 1 3 5 0.05 % by wt. of AO L plus 0.1 % by wt.of HALS A plus 4.3 5.2 7.3 3.2 3.7 4.3 0.1 % by wt.of HA 5 0.1 % by wt.of HALS A plus 0.1 % by wt. of HA 5 4.1 6.1 8.0 3.7 3.6 3.8 Extrusion at 280°C; Example 29: Following the general procedure of Example 16, polypropylene (®Propathene HF 26, ICI) containing 0.1 % by weight of calcium stearate and the additional stabilizers listed in the table below is extruded at 300°C. The melt flow rate and yellowness index values are measured after the 1st, 3rd and 5th extrusions to assess the efficacy of the stabilizers present in the test sample. A mixture of phenolic antioxidant and hydroxylamine, which may optionally contain a phosphorus compound is very effective in stabilizing the melt flow rate value without perceptible discoloration.

Claims: A stabilized composition which comprises (a) a saturated polyolefin or mixture thereof, and (b) at least one long chain N,N-dialkylhydroxylamine of the formula I T₁T₂NOH wherein T₁ and T₂ are independently hexadecyl, heptadecyl or octadecyl, with the proviso that, if T₁ and T₂ have the same meaning, they are not octadecyl. A composition according to claim 1 wherein T₁ and T₂ are hexadecyl or octadecyl. A composition according to claim 1 wherein T₁ is hexadecyl and T₂ is heptadecyl or octadecyl. A composition according to claim 1 wherein T₁ is heptadecyl and T₂ is octadecyl. A stabilized composition which comprises (a) a saturated polyolefin or mixture thereof, and (b) a long chain N,N-dialkylhydroxylamine mixture of the formula II T₃T₄NOH wherein T₃ and T₄ are the alkyl mixture found in hydrogenated tallow amine. A composition according to claims 1 to 5 wherein component (a) is a polyolefin which is a homopolymer or copolymer of an alpha-olefin. A composition according to claim 6 wherein the polyolefin is selected from the group consisting of polypropylene, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, poly(butene-1), ethylene/vinyl acetate copolymer, ethylene/propylene copolymer and copolymers of ethylene or of propylene with other alpha-olefins. A composition according to claim 6 wherein the polyolefin is polypropylene, high density polyethylene, ethylene/propylene copolymer or a copolymer of ethylene or of propylene with another alpha-olefin, low density polyethylene or linear low density polyethylene. A composition according to claims 1 to 8 which additionally contains a stabilizer or mixture of stabilizers selected from the group consisting of the alkaline metal salts of fatty acids, the phenolic antioxidants, the hindered amine light stabilizers, the ultraviolet light absorbers, the organic phosphorus compounds and the thiosynergists. A composition according to claim 9 which additionally contains (c) an alkaline metal salt of a fatty acid or mixture thereof. A composition according to claim 9 which additionally contains (c) an alkaline metal salt of a fatty acid or mixture thereof, and (d) a phenolic antioxidant or mixture thereof. A composition according to claim 9 which additionally contains (e) a hindered amine light stabilizer or mixture thereof. A composition according to claim 9 which additionally contains (f) an organic phosphorus compound or mixture thereof. A composition according to claim 9 which additionally contains (c) an alkaline metal salt of a fatty acid or mixture thereof, and (e) a hindered amine light stabilizer or mixture thereof. A composition according to claim 9 which additionally contains (c) an alkaline metal salt of a fatty acid or mixture thereof, (d) a phenolic antioxidant or mixture thereof, and (e) a hindered amine light stabilizer or mixture thereof. A composition according to claim 9 which additionally contains (c) an alkaline metal salt of a fatty acid or mixture thereof, (d) a phenolic antioxidant or mixture thereof, and (f) an organic phosphorus compound or mixture thereof. A composition according to claim 9 which additionally contains (c) an alkaline metal salt of a fatty acid or mixture thereof, and (f) an organic phosphorus compound or mixture thereof. A composition according to claim 9 which additionally contains (e) a hindered amine light stabilizer or mixture thereof, and (f) an organic phosphorus compound or mixture thereof. A composition according to claim 9 which additionally contains (c) an alkaline metal salt of a fatty acid or mixture thereof, (e) a hindered amine light stabilizer or mixture thereof, and (f) an organic phosphorus compound or mixture thereof. A composition according to claim 9 which additionally contains (c) an alkaline metal salt of a fatty acid or mixture thereof, (d) a phenolic antioxidant or mixture thereof, (e) a hindered amine light stabilizer or mixture thereof, and (f) an organic phosphorus compound or mixture thereof. A composition according to claim 9 which additionally contains (d) a phenolic antioxidant or mixture thereof.

Inventors: PATEL AMBELAL R, RAVICHANDRAN RAMANATHAN, SELTZER RAYMOND, PATEL, AMBELAL R., RAVICHANDRAN, RAMANATHAN, SELTZER, RAYMOND
Applicants: CIBA GEIGY AG, CIBA-GEIGY AG
Application year: 1988
Main classification: C08K5
IPC codes: C08K5, C08L23, C08L31