MXPA00001064A - Olefin polymer composition having low smoke generation and fiber, film and fabric prepared therefrom - Google Patents

Abstract

A polymer composition and fiber, film and fabric prepared therefrom. The composition contains (i) an acid neutralizing agent other than a metallic salt of a saturated or unsaturated fatty acid, (ii) a processing aid comprising a metallic salt of a saturated or unsaturated fatty acid, the metallic salt of a saturated or unsaturated being present in a maximum amount of 200 ppm, a stabilizer system containing (a) a phosphite selected from the group consisting of 2,2',2''-nitrilo[triethyl-tris(3, 3',5,5'-tetra-tert.butyl-1,1-biphenyl-2,2'-diyl)phosphite]and tris(2, 4-di-tert-butylphenyl)phosphite;and (b) a N,N-dialkylhydroxylamine. Also disclosed is a method for preparing a polyolefin fiber, film or fabric which includes (A) incorporating the above additives into an olefin polymer, thereby producing a stabilized polyolefin polymer;and (B) extruding the stabilized olefin polymer through a die, thereby producing an olefin polymer fiber or film. A woven or non-woven fabric may be prepared from the olefin polymer fiber or film.

Description

"COMPOSITION OF POLYMER OF Q EF1NA THAT HAS LOW GENERATION OF SMOKE AND FIBER, MOVIE AND TELE PREPARED OF THE SAME" BACKGROUND OF THE INVENTION Olefin polymers, especially polypropylene, are commonly spun into fibers, a film or sheet by extruding the molten polymer through the holes in the die such as a spinneret, film or sheet dies, rapidly quenching the melted filament, the film or sheet, orienting the filament, film or sheet and thermally solidifying the filament, film or oriented sheet before winding in a coil. Woven and non-woven fabrics are commonly made from this filament, film or ho3a. A problem associated with polyolefins produced using Ziegler-Natta type catalysts is the generation of "smoke" visible during the melt extrusion of polyolefin during fiber spinning and film extrusion operations. The "smoke" is fired in the matrix, and is believed to comprise volatile organic compounds on the scale of 20 to 50 carbon atoms. These fired volatile organic compounds subsequently condense and coat the equipment with problems resulting from non-uniformity of the non-woven fabrics formed from these fibers or from films due to matrix deposits caused by volatile organic compounds. Efforts to reduce or eliminate smoke have been partially satisfactory at best. Minimizing both the melting temperature and the dwell time of the extrusion apparatus to less than certain levels can create processing problems. The devolatilization of the polymer feedstock by heating before extrusion can reduce the generation of smoke by approximately 20 percent. In contrast, the present invention can reduce smoke by up to 86 percent or more. The incorporation of various additives in and / or to the olefin polymer materials to improve thermal stability, ultraviolet light resistance and processability is already known. For example, the inclusion of a neutralizing agent in the olefin polymer compositions is necessary due to the small amounts of catalyst residue contained within the olefin polymer. These catalyst residues can cause corrosion of the processing equipment such as the mold surfaces and the edges of the die. The addition of a neutralization agent has been appropriate to eliminate or at least reduce the potential for corrosion due to these residues. The selection of the neutralization agent is important because it can affect the total acidity / basicity of an olefin polymer composition and can influence the reactions of many of the organic additives in the polymer composition. In addition, the release properties of polyolefin can be affected by the acid neutralizing agent. In practice, metal stearates such as sodium, calcium and zinc, are commonly added to the olefin polymer materials as an acid neutralizing agent, with calcium stearate being the most common. Calcium stearate is used predominantly because it also functions as an external lubricant and processing aid in addition to acting as an acid neutralizing agent. In general, it is necessary to add calcium stearate in an amount of at least 500 parts per million to ensure that it can function as an effective acid neutralizing agent. The phosphite compounds, including 2, 2 ', 2"-nitrile [triethyl-tris (3,3', 5,5 ', tetra-tert-butyl-1,1-biphenyl-2,2', diyl) phosphite] are typically added to the polyolefin compositions to stabilize them against thermal and oxidative degradation. Various forms of 2, 2 ', 2"-nitrile [triethyl-tris (3, 3', 5, 5 ', tetra-tert-butyl-1, l-b-phenyl-2 are known., 2 ', diyl) phosphite]. For example, U.S. Patent Number 5,326,802 discloses a beta-crystalline modification of r 2, 2 ', 2"-nitrile [triethyl-tris (3,3', 5,5 ', tetra-tert-butyl-1 , 1-bifeni1-2, 2 ', diyl) phosphite]. Example 6 discloses the stabilization of polypropylene which also contains 750 parts per million of calcium stearate. U.S. Patent Nos. 5,331,031 and 5,405,893 disclose a gamma crystal modification of 2, 2 ', 2"-nitrile [triethyl-tris (3, 3', 5,5 ', tetra-tert-butyl-1, 1- b? pheny1-2, 2 ', diyl) phosphite]. Example 4 illustrates the stabilization of polypropylene which also contains 750 parts per million of calcium stearate. A solid amorphous modification of 2,2,, 2,, -nitrile [tr? Et? L-tris (3,3 ', 5,5', tetra-tert-butyl-1,1-biphenyl-2, 2 ' , diyl) phosphite] is disclosed by US Pat. No. 5,276,076. Example 3 illustrates the stabilization of polypropylene which also contains 750 parts per million of calcium stearate. The use of N, N-dialkylhydroxyamines to stabilize the polyolefins is also known. Therefore, U.S. Patent No. 4,668,721 discloses that hydroxylamine derivatives can be used to stabilize polyolefin compositions against degradation due to extrusion, exposure to natural gas combustion products, gamma radiation or during storage. The hydroxylamine derivative can have a chemical structure that conforms to one of fourteen structural formulas. In Example 21, a combination of hydroxylamine and calcium stearate (1000 parts per million) is said to be far superior to hydroxylamine alone with respect to the yellowing resistance of the processed polypropylene at 260 ° C. US Patent No. 4,876,300 discloses that long chain N, N-dialkylhydroxylamines can be used as process stabilizers for polyolefin compositions, in order to minimize discoloration and increase melt flow rate due to extrusion. Examples 16 to 18 and 20 illustrate the stabilization of the polypropylene process containing 1,000 parts per million of calcium stearate, while Example 19 illustrates the stabilization of the polypropylene process containing 1000 parts per million of zinc stearate. International Patent Publication Number WO 94/24344 discloses a stabilized polypropylene with an effective amount of a selected hindered amine, a selected N, N-dialkylhydroxylamine and a phosphite which can be 2, 2 ', 2"-nitrile [triethyl-tris (3, 3', 5, 5 ', tetra-tert-butyl-1, l-biphenyl-2, 2', diyl) phosphite]. The polypropylene composition is free or essentially free of any traditionally used phenolic antioxidant, and said to possess improved light stability, improved long-term heat stability and especially improved gas fading stability. All the formulations disclosed in the examples contain 750 parts per million of calcium stearate. An object of the invention is to provide a The stabilized olefin polymer composition exhibits good processing characteristics and yet generates a minimal amount of smoke during extrusion in a fiber or film. Still another object of the invention is to provide a method for reducing the volatile organic compounds generated during the production of polyolefin fiber and film by up to 86 percent.

BRIEF COMPENDIUM OF THE INVENTION In one aspect, the present invention relates to a polymer composition comprising an olefin polymer that contains (i) an acid neutralizing agent that is not a metal salt of a saturated or unsaturated fatty acid, (ii) an auxiliary of processing comprising a metal salt of a saturated or unsaturated fatty acid, the metal salt of the saturated or unsaturated acid being present in a maximum amount of 200 parts per million, (iii) a stabilizer system comprising (a) a phosphite which is selected from the group consisting of 2, 2 ', 2"-nitrile [triethyl-tris (3, 3', 5, 5 ', Tetra-tert-butyl-1, 1-biphenyl-2,2 ', diyl) phosphite] and tris (2,4-di-tert-butylphenyl) phosphite / and (b) an N, N-dialkylhydroxylamine. In another aspect, the present invention relates to a method for preparing an olefin polymer fiber or film 15 comprising (A) incorporating the following additives into an olefin polymer; (i) an acid neutralizing agent other than the metal salt of a saturated or non-saturated fatty acid, (ii) a processing aid comprising a metal salt of a saturated or unsaturated fatty acid and the metal salt of a saturated or unsaturated acid present in a maximum amount of 200 parts per million, (iii) a stabilizer system comprising (a) a phosphite selected from the group consisting of 2, 2 ', 2"-nitrile [triethyltris (3.3', 5.5 ') , tetra-tert-butyl-1, 1-bi phenyl-2, 2 ', diyl) phosphite] and tris (2,4-d? -tert-butylphenyl) phosphite; and (b) an N, N-dialkylhydroxylamine, thereby producing a stabilized polyolefin polymer; and (B) extruding the stabilized olefin polymer through a die, thereby producing an olefin polymer film or fiber.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES: It has been unexpectedly discovered that it is possible to provide a stabilized olefin polymer composition that exhibits good processing characteristics and yet still generates a minimal amount of smoke during extrusion into a fiber or movie. This combination of desirable properties is exhibited by careful preparation of the polyolefin composition. First, the present invention employs an acid neutralizing agent that is not the metal salt of a saturated or unsaturated fatty acid. Second, the The composition of the invention contains an unconventionally low amount of stearate which, by itself, it is ineffective to function as an acid neutralizer, but it is an effective processing agent. Third, a stabilizer system comprising selected phosphites and a hydroxylamine acts to reduce the smoke generated by the presence of calcium stearate. The resulting composition has acceptable processing characteristics typical of polyolefins containing conventional amounts of calcium stearate, while producing significantly less smoke during extrusion in a fiber or film than polyolefin compositions containing conventional amounts of calcium stearate. Controlled rheology olefin polymers are prepared by polymerizing the olefin monomers to a relatively high weight average molecular weight, which are then treated ("vis-disintegrate") with peroxide to reduce their molecular weight to a desired average. Alternatively, the controlled rheology polymers can be prepared using a Ziegler-Natta catalyst system which is known to provide the desired weight average molecular weight and using a sufficient amount of a chain transfer agent, such as hydrogen, during the polymerization to achieve the desired melt flow rate.

The olefin polymer is derived by polymerizing at least one mono-alpha-olefin, such as ethylene, propylene, isobutylene, buten-1,3-methyl-1-butene and 4-methyl-1-pentene. The polyethylene, both the homopolymer and the copolymer, can for example polyethylene of medium density, high density or low linear density. The copolymers of the mono-alpha-olefins can also be used in the present composition, for example the copolymers of ethylene / propylene, copolymers of propylene / buten-1, copolymers of propylene / octen-1, copolymers of ethylene / buten-1 , ethylene / octen-1 copolymer as well as the ethylene / vinyl acetate copolymers. The modified or heterophasic modified olefin polymers can also be used in the compositions of this invention. Suitable heterophasic olefin polymers include (a) an olefin polymer composition comprising; (i) from about 10 parts to about 60 parts by weight of a crystalline propylene homopolymer having an isotactic index greater than 80, or a crystalline copolymer selected from the group consisting of (a) propylene and ethylene, (b) propylene, ethylene and an alpha-olefin of 4 carbon atoms to 8 carbon atoms, and (c) propylene and an alpha-olefin of 4 carbon atoms to 8 carbon atoms, the copolymer having a propylene content of more than 85 percent by weight and an isotactic index greater than 85; (ii) from about 5 parts to about 25 parts by weight of an ethylene-propylene copolymer or an alpha-olefin of 4 carbon atoms to 8 carbon atoms which is insoluble in xylene at room temperature; and (iii) from about 30 parts to about 70 parts by weight of an elastomeric copolymer selected from the group consisting of (a) ethylene and propylene, (b) ethylene, propylene, and an alpha-olefin of 4 carbon atoms to 8 carbon atoms, and (c) ethylene and an alpha-olefin of 4 carbon atoms to 8 carbon atoms, the copolymer optionally contains from about 0.5 percent to about 10 percent by weight of a diene, and contains less 70 percent ethylene and xylene is soluble at room temperature and has a mtrinic viscosity of about 1.5 percent at about 4.0 deciliters per gram in tetrahydronaphthalene at 135 ° C; the total of (n) and (in), based on the total olefma polymer composition being from about 50 percent to about 90 percent and the weight ratio of (ii) / (iii) being less than 0.4, in wherein the composition is prepared by polymerizing in at least two stages and having a flexural modulus of less than 150 mPa; (b) an olefin polymer comprising: (i) from about 10 percent to about 60 percent of a propylene homopolymer having an isotactic index greater than 80, or a crystalline copolymer selected from the group consisting of ( a) ethylene and propylene, (b) ethylene, propylene and alpha-olefin of 4 carbon atoms to 8 carbon atoms, and (c) ethylene and an alpha-olefin of 4 carbon atoms to 8 carbon atoms, having the copolymer a propylene content greater than 85 percent and an isotactic index greater than 85 percent; (n) from about 20 percent to about 60 percent of an amorphous copolymer selected from the group consisting of (a) ethylene and propylene, (b) ethylene, propylene, and an alpha-olefin of 4 carbon atoms a 8 carbon atoms, and (c) ethylene and an alpha-olefin of 4 carbon atoms to 8 carbon atoms, the copolymer optionally containing from about 0.5 percent to about 10 percent of a diene and containing less than 70 percent of ethylene and being soluble in xylene at room temperature; and (iii) from about 3 percent to about 40 percent of an ethylene-propylene copolymer or an alpha-olefin of 4 carbon atoms to 8 carbon atoms that is insoluble in xylene at room temperature; wherein the composition has a flexural modulus greater than 150 but less than 1200 mPa, preferably from 200 to 1100 mPa, more preferably from 200 to 1000 mPa, which is measured at 23 ° C, a frequency measurement of 1 Hz and a scanning temperature of 2 ° C per minute; and (c) an olefin polymer composition comprising: (i) from about 30 percent to about 98 percent of a polymeric material that is selected from the group consisting of a polypropylene homopolymer having an isotactic index greater than 90 , and a crystalline copolymer having an isotactic index greater than 85 of propylene and at least one alpha-olefin of the formula CH 2 = CHR, wherein R is H or an alkyl group of 2 carbon atoms to 6 carbon atoms , the alpha-olefin being less than 10 percent of the copolymer when R is H and being less than 20 percent when R is an alkyl group of 2 carbon atoms to 6 carbon atoms or a combination thereof with R = H, and (ii) from about 2 percent to about 70 percent of an elastomeric propylene copolymer and an alpha-olefin of the formula CH 2 = CHR, wherein R is H or an alkyl group of 2 carbon atoms at 8 carbon atoms, being the alpha-olefin from about 45 percent to about 75 percent of the elastomeric copolymer, and about 10 percent to about 40 percent of the elastomeric copolymer being more soluble in xylene at room temperature, or an elastomeric copolymer of ethylene and an alpha C4-C8-olefin having an alpha-olefin content of about 15 percent to about 60 percent. As used herein, the room temperature or the room temperature is about 25 ° C. The total amount of ethylene polymerized in (a) is preferably from about 10 percent to about 40 percent by weight. Alpha-olefins of 4 to 8 carbon atoms useful in the preparation of (a) and (b) include, for example, butene-1; pentene-1; hexene-1; 4-methyl-l-pentene and octene-1. The diene when present is typically a butadiene, 1,4-hexadiene; 1, 5-exadiene or ethylidene norbornene. The propylene polymer materials (a) and (b) can be prepared by polymerization in at least two stages, wherein in the first stage the propylene or the propylene and ethylene or an alpha-olefin, or propylene, ethylene and a alpha-olefin are polymerized to form component (i) of (a) or (b), and in the following stages mixtures of ethylene and propylene or of alpha-olefin, or ethylene, propylene and alpha-olefin, and optionally a ti - diene, they polymerize to form the components (i) and (iii) of (a) and (b). The polymerization of (a) and (b) can be carried out in the liquid phase, the gas phase, or the liquid-gas phase using separate reactors, all of which can be carried out either batchwise or continuously. For example, it is possible to carry out the polymerization of component (i) using liquid propylene as the diluent, and the polymerization of components (ii) and (iii) in the gas phase, without intermediate steps except as regards to the partial degassing of propylene. The entire gas phase is the preferred method. The preparation of the propylene polymer material (a) is described in greater detail in U.S. Patent Nos. 5,212,246 and 5,409,992, which are incorporated herein by reference. The preparation of the propylene polymer material (b) is described in greater detail in U.S. Patent Nos. 3,302,454 and 5,409,992, which are also incorporated herein by reference. The polymer composition (c) can be obtained by monomer sequence polymerization in the presence of Ziegler-Natta catalysts, or by mechanical mixing of components (i) and (ii). This sequence polymerization is described in greater detail in U.S. Patent No. 5,486,419, which is incorporated herein by reference. The sequence polymerization can be carried out with a mixture of the Ziegler-Natta and metallocene catalysts or using a Ziegler-Natta catalyst in one reactor, preferably in the first reactor, and a metallocene catalyst in the other reactor (s) , preferably the reactor (s) after the first reactor. Mixtures of homopolymers or mixtures of olefin copolymers or mixtures of both can be used. The olefin polymer is preferably a crystalline propylene polymer, more preferably either a crystalline propylene homopolymer having an isotactic index greater than 90, more preferably greater than 93, a crystalline propylene random copolymer either ethylene or alpha -olefin of 4 carbon atoms to 10 carbon atoms with an isotactic index greater than 85. The propylene polymer is preferably vis-disintegrated at a melt flow rate ("MFR") of 15 to 50 grams per 10 minutes more preferably 25 to 38 grams per 10 minutes which is measured according to the American Society for the Testing of Materials 1238, Condition L. These propylene polymers can be obtained commercially from Montell USA Inc.

The process of vis-integrating a propylene polymer material is well known to those skilled in the art. It is generally carried out in the following manner: the propylene polymer in particulate form, eg, "as polymerized" or pelletized flake, has been sprayed thereinto and mixed therewith with a free radical or prodegradant generating source, eg, peroxide in liquid or powder form absorbed onto and / or in a carrier, eg, a polypropylene / peroxide concentrate. The propylene polymer and the peroxide or the propylene / peroxide polymer concentrate is then introduced into a means for thermally plasticizing or melt mixing and transferring the mixture, e.g., to an extrusion apparatus at elevated temperature. The residence time and the temperature are controlled relative to the specific peroxide selected (ie, based on the half-life of the peroxide at the process temperature of the extrusion apparatus) in order to effect the desired degree of polymer chain degradation. The net result is to reduce the molecular weight distribution of the propylene polymer as well as to reduce the total molecular weight and thereby increase the MFR relative to the propylene polymer as it was polymerized. For example, a propylene polymer with a fractionated MFR (i.e., less than 1), or a polymer of ? & ^^^^ i j_ i¿¿ Y ^ Yi? ^^ prop leno with an MFR of 0.5 to 10 grams per 10 minutes, selectively disintegrate towards an MFR of 15-50, preferably 25 to 38 grams per 10 minutes, by selecting the type of peroxide, at the temperature of the extrusion apparatus and the residence time in the extrusion apparatus without experiments undue. Sufficient care must be taken in the practice of the process to avoid crosslinking in the presence of an ethylene-containing copolymer, typically crosslinking will be avoided when the ethylene content of the copolymer is sufficiently low. The polyolefin composition contains a processing aid comprising a metal salt of a saturated or unsaturated fatty acid, which is present in a maximum amount of 200 parts per million. Calcium stearate is preferred and is preferably present in an amount of 100 to 200 parts per million, still more preferably in an amount of 125 to 175 parts per million. The composition of the polymer of the present invention also contains an acid neutralizing agent that is not a metal salt of a saturated or unsaturated fatty acid, and particularly, metal stearates and especially calcium stearate. Fatty acids typically have from 4 to 22 carbon atoms with, &; * - a terminal carboxyl group (COOH). The typical metals are those in Group IA and IIA of the Periodic Table. Acid neutralization compounds suitable for use in the present invention include zeolite structures (hydrotalcite, both natural and synthetic) aluminum silicate, calcium carbonate, sodium benzoate, and oxides and hydroxides of Group IA and IIA metals. Calcium lactate, calcium hydroxide, calcium oxide or mixtures thereof are especially preferred. Hydrotalcite, which typically contains 3 percent to 10 percent by weight of calcium stearate, based on the weight of hydrotalcite, can be used if your contribution of calcium stearate is taken into account to adjust the amount of calcium stearate present in the polyolefin composition. An effective amount of the acid neutralizing agent will vary from 200 to 2000 parts per million of polymer, preferably from 200 to 1,000 parts per million of polymer depending on the acidity of the polyolefin and the equivalent weight of the acid neutralizing agent. In the case of polypropylene, a preferred amount of an acid neutralizing agent such as calcium lactate, ranges from 200 to 300 parts per million of polymer.

The applicants do not wish to be limited by any theory of the invention. It is currently believed that the acid neutralizing agent can act alone or together with the amount not conventionally low calcium stearate to neutralize the acids \ present in the polymer. More specifically, the effective amount of the acid neutralizing agent may depend on the equivalent weight of the specific acid neutralizing agent selected together with the amount of the calcium stearate processing aid present in the polymer. In this way, calcium stearate can have a double function by (1) serving as a processing agent and (2) acting in accordance with the acid neutralizing agent to neutralize the acids contained within the polymer composition. Importantly, the amounts of calcium stearate, per se, are insufficient to completely neutralize the acids present in the polymer composition. 20 The phosphite stabilizer can be either 2,2 ', 2"-nitrile [triethyl-tris (3, 3', 5,5 ', tetra-tert-butyl-1, 1-biphenyl-2,2', diyl) phosphite] or tris (2 , 4-di-tert-butylphenyl) phosphite. Both of these compounds can be obtained commercially. The preparation of 2, 2 ', 2' '- 25 nitrile [triethyl-tris (3,3', 5,5 ', tet a-tert-butyl-1, 1-biphenyl-2, 2', iyl) phosphite ] is disclosed in U.S. Patent No. 4,318,845, the disclosure of which is hereby incorporated by reference in its entirety. The N, Nd? Alkylhydroxyallan should have a hydroxyl group linked to the nitrogen atom, and preferably conform to the formula: R ^ NOH wherein R] _ and R2 are independently alkyl of 1 to 36 carbon atoms. carbon that is not replaced or replaced with hydroxyl. Exemplary hydroxylamines that fall within the above formula include N, N-distearylhydroxylamine and di (hydrogenated tallow) amine. A typical di (hydrogenated tallow) amine has the following alkyl substituent distribution: R ^ NH Rl R2 c16 c14 1.9 c16 c16 12.4 c16 Cl7 2.8 ? & jSSStttkikt * »* '*. : * *. -Í c16 c18 36.0 C17 C ^ 3.9 C18 C- 39.0 Other 4.0 The di (hydrogenated tallow) amine that originates from animal sources can vary to a certain degree in the specific distribution of the alkyl substituents, but the di (hydrogenated tallow) amine contains predominant amounts of N, N-dihexadecylamine, N, N- dioctaldecylamine and N-hexadecyl-N-octadecylamine. The individual components of the mixture can be separated by distillation at high vacuum. However, for the purposes of this invention, there is no need to carry out this separation and the hydroxylamine prepared from the di (hydrogenated tallow) amine is a preferred embodiment of the present invention. The long chain N, N-d? Alkylhydroxylamines can be prepared by a number of methods. These include (a) oxidation of the corresponding secondary amine in aqueous hydrogen peroxide to form the desired N, N-dialkylhydroxylamine directly; (b) adding the secondary amine to the alpha, beta-unsaturated compound such as an alkyl acrylate to form a Michael addition product, which in turn is oxidized to the corresponding tertiary amine oxide using aqueous hydrogen peroxide , and followed by removal of the alpha, beta-unsaturated compound by the Cope reaction to provide 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 in the desired hydroxylamine derivative. An effective amount of the stabilizer system will typically vary from 250 to 2000 parts per million of polymer, with a preferred amount being from 700 to 1500 parts per million of polymer. The stabilizer system can contain from 10 percent to 80 percent N, N-dialkylhydroxylamine and from 90 percent to 20 percent phosphite. The stabilizer system of the present invention may also contain at least one other stabilizing compound. For example, another compound of phosphite in partial replacement of the primary phosphite stabilizer compounds for economic reasons. However, the inventor has discovered that this substitution can only be partial (ie, about 50 percent); the complete replacement of the primary phosphite compounds significantly increases the generation of smoke. Suitable partial phosphite replacements include tris (2, -di-tert-butylphenyl) phosphite and 2,4,6-tert-butylphenyl-2-butyl-2-ethyl-1,3-propanediol phosphite. The stabilizing system may also include conventional stabilizing compounds with little or no detrimental effect on smoke generation. For example, a hindered amine light stabilizer (HALS) can be added to the stabilizer system. Suitable HALS include poly [6- [(1,1,3,3-tetramethyl-butyl) amino-s-triazine, 2,4-yl] 2,2,6,6-tetramethyl-4-pipepndyl) imino] hexamethylene [2, 2, 6, 6-tetramethyl-4-p? peridyl) imino] and 1, 3, 5-triazin-2,4,6-triamine-N, N "- [1,2-ethanediylbis] N- (3- [4,6-bis- (butyl-1,2,6,6-pentamethyl-4-piperidyl) amine] propyl [N, N-dibutyl-N, N-bis (1 , 2, 2, 6, 6-pentamethyl-4-piperidinyl.) Similarly, phenolic stabilizers such as tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane and tetrakis [methylene- 3- (3 ', 5'-di-tert-butyl-4' -hydroxyphenyl) propionate] methane can be added to increase the thermal stability The stabilized polyolefin composition can contain other additives as appropriate for the intended use of Composition These additives include antistatic agents, flame-retardant agents, antiblocking agents, lubricants, pigments, optical brighteners, nucleators and clarifiers. Samples of the stabilizer system can be incorporated into the olefin polymer in any conventional manner such as by drying mixing the stabilizer system directly with polymer granules, by means of mixers and the Henschel mixers. The thick solutions, emulsions and suspensions of the stabilizer system can be sprayed into or mixed with the granulated polymer. For example, the stabilizing components can be coated on the olefin polymer granules in a fluidized bed according to the processes of U.S. Patent No. 5,141,772, the disclosure of which is hereby incorporated in its entirety. The stabilizer components can also be mixed with melted polymers by means of a Banbury mixer, a Bradbender mixer, a roller mill or screw extrusion apparatus.

The stabilizer system can also be added to the olefin polymer in the form of a master batch in accordance with the conventional techniques disclosed in US Pat. No. 5,236,962 the disclosure of which is hereby incorporated by reference in its entirety. The stabilized polyolefin composition of the present invention is particularly suitable to be manufactured into a fiber or film using conventional techniques and apparatus. More specifically, the stabilized olefin polymer can be extruded at conventional temperatures (i.e., 210 ° C to 280 ° C) through a die, cooled rapidly, partially or completely oriented and thermally solidified before winding in a coil to undergo additional processing and in a fiber bonded by spinning or blown by melting and finally in continuous woven and nonwoven webs. As used herein, the term "non-woven web" means a continuous web having a structure of individual fibers or threads that intertwine but not in an identifiable manner as a continuous ribbon of knitted fabric. Non-woven webs have been formed from many processes such as, for example, meltblowing processes, • * processes, bonding by spinning and continuous carded ribbon processes linked The basis weight of non-woven webs is usually expressed in ounces of material per square yard or grams per square meter and useful fiber diameters are usually expressed in microns. As used herein, the term "spunbond fibers" refers to small diameter fibers that are formed by extruding the molten thermoplastic material as filaments of a plurality of usually circular fine filament capillaries in the diameter of the extruded filaments. then quickly reduced by for example, in the North American Patents Numbers 4,340,563, 3,692,618, 3,802,817, 3,338,992, 3,341,394, 3,502,763 and 3,542,615. Spunbond fibers are usually not sticky when they are deposited on a collector surface. Spunbonded fibers are generally continuous and have average diameters (of a sample of at least 10) greater than 7 microns, more particularly, between about 10 and 20 microns. As used herein, the term "melt blown fibers" means fibers formed by extruding a molten thermoplastic material through a plurality of matrix capillaries, usually thin circular, such as melted strands or filaments at high converging velocity, usually hot streams of gas (eg, air) that attenuates the filaments of the molten thermoplastic material to reduce its diameter, which can be up to the diameter of the microfiber. Then, the melt blown fibers are carried by a high velocity gas stream and are deposited on the collector surface to form a continuous web of randomly dispersed meltblown fibers. This process is disclosed in U.S. Patent Number 3,849,241. Melt-blown fibers are microfibers that can be continuous or discontinuous, are generally smaller than 10 microns in average diameter, and are usually sticky when deposited onto a collecting surface. U.S. Patent No. 5,667,562 discloses the production of fiber media from polypropylene based fibers using a spin bonding process and is incorporated herein by reference. A particularly preferred ream composition comprises 250 parts per million calcium lactate as an acid neutralizing agent. 150 parts per million calcium stearate as a processing aid; and the combination of 400 parts per million of 2, 2 ', 2"-nitrile [triethyl-tris (3,3', 5, 5 ', tetra-tert-butyl-1, 1-biphenyl-2, 2' , dnl) phosphite], 800 parts per million N, N-di (esteapl) hydroxyl-amma; and 500 parts per million of tetrakis [methylene (3,5-d? -tert-butyl-4-hydroxyhydrocinnamate)] methane as the stabilizing agent. EXAMPLES: These examples are presented for the purpose of illustration only and should not be construed as limiting the nature or scope of the invention disclosed herein in any manner: The chemical identities of the products used in the formulations presented below are the following: Olefin polymer Polypropylene polymer PF-305 commercially available from Montell USA Inc. Phosphite Irgafos 12 2, 2 ', 2"-nitrile [triethyl-tris (3, 3 ', 5, 5', tetra-tert-butyl-1, 1-bifeni1-2, 2 ', diyl) phosphite], commercially available from Ciba Specialty Chemicals Corporation. Hydroxylamine FS-042 N, N-di (esteapl) hydroxylamine, commercially available from Ciba Specialty Chemicals Corporation. Preventing Phenolic Antioxidant Irganox 1076 octadecyl-3, 5-di-tert-butyl-4-hydroxy hydrocinmate, commercially available from Ciba Specialty Chemicals Corporation. Various Calcium Lactate Pationic 1240, commercially available from American Ingredients Company. DHT-4A hydrotalcite, commercially available from Kyowa Chemicals Industry, Co. Ltd. EXAMPLE I Three formulations were prepared based on a polypropylene feedstock prepared from a commercially produced polypropylene flake having a soluble xylene content at room temperature of 4.0. percent and an initial MFR of 1.5 grams per 10 minutes, which is measured according to the American Society for the Testing of Materials 1238, Condition L, and which vis-disintegrates to a white MFR of 38 grams per 10 minutes. The sample formulations were then mixed together in a Kokneader extrusion apparatus and pelleted. Smoke generation was measured by extruding 3,048-meter samples of each formulation at a rate of 3,048 meters per hour at 260 ° C through a 3,175-centimeter fiber extrusion machine rapidly cooling under moderate conditions. The volatile organic compounds of the flushed smoke aspirated from the orifice of the matrix were measured and recorded through a vacuum system to a sample chamber where a laser particle counter measured the concentration of the volatile particles in milligrams per cubic meter. The results were recorded in a strip graph recording apparatus. The formulations of the sample and its smoke measurements are listed below: Table 1 10 PF-305 1-1 1-2 Irganox 1076 (ppm) 1,000, 1,000 1,000 Irgafos 12 (ppm) 400 400 FS-042 (ppm) 800 800 CaSt (ppm) 500 500 150 Pationic 1240 (ppm) 200 Irg. 12: FS-042 0.5 0.5 Smoke (mg / cm) 180 42 24 The examination in Table I illustrates the dramatic reduction in the generation of the volatile organic compound exhibited by the present invention. More particularly, sample 1-2 of the invention achieved a reduction of 86 5 percent in the generation of the volatile organic compound compared to the control sample PF-305, which contains a conventional amount of calcium stearate and 1000 parts by weight. million phenolic hindered antioxidant, and 42 percent reduction compared to the sample -1 of control, which contains a conventional amount of calcium stearate and the same stabilizing additives as the formulation of the invention. Other features, advantages and embodiments of the invention disclosed herein will be readily apparent to those knowledgeable about the technique after reading the previous expositions. In this regard, specific embodiments of the invention have been described in considerable detail and variations and modifications of these embodiments can be made without deviate from the spirit and scope of the invention as described and claimed.

Claims (24)

CLAIMS:

1. A polymer composition comprising an olefin polymer containing (i) an acid neutralizing agent that is not a metal salt of a saturated or unsaturated fatty acid, (ii) a processing aid comprising a metal salt of a saturated or unsaturated fatty acid, and the metal salt of a saturated or unsaturated acid present in a maximum amount of 200 parts per million, (iii) a stabilizing system comprising (a) a phosphite selected from the group consisting of 2, 2 ', 2"-nitrile [triethyl-tris (3, 3', 5, 5 ', tetra-tert-butyl-1, l- biphenyl-2, 2 ', diyl) phosphite] and tris (2,4-di-tert-butylphenyl) phosphite; and (b) an N, N-dialkylhydroxylamine.

2. The polymer composition of claim 1, wherein the acid neutralizing agent is at least one member that is selected from the group consisting of hydrotalcites, aluminum silicate and oxides and hydroxides of Group II metals.

3. The polyolefin composition of claim 2, wherein the acid neutralizing agent is selected from the group consisting of -55-lactate. calcium, calcium hydroxide, calcium oxide and mixture thereof.

4. The polyolefin composition of claim 1, wherein the processing aid 5 comprises calcium stearate in an amount of 100 to 200 parts per million.

5. The polyolefin composition of claim 4, wherein the calcium stearate is present in an amount of 125 to 175 parts per million.

6. The polyolefin composition of claim 1, wherein the phosphite is 2, 2 ', 2"-nitrile [triethyl-tris (3, 3', 5, 5 ', tetra-tert-butyl-1, 1-biphenyl-2, 2 ', diyl) phosphite].

7. The polymer composition according to claim 1, wherein the N, N-dialkylhydroxylamine is conformed to the formula: R! R N0H wherein R ^ and R2 are independently alkyl of 1 to 36 carbon atoms, which it is not replaced or replaced with hydroxyl.

8. The polymer composition of claim 7, wherein the N, N-dialkylhydroxylamine is N, N-distearylhydroxylamine. *. «&? .*, 3 * 6 4

9. The polymer composition of claim 7, wherein the N, N-d? Alk? Lh? Drox? Lanama comprises di (hydrogenated tallow) hydroxyl amine.

The polyolefin composition of claim 1, wherein the stabilizer system is present in an amount of 250 to 2000 parts per million of the polymer.

11. The polyolefin composition of claim 10, wherein the stabilizing system is present in an amount of 700 to 1500 parts per million of the polymer.

The polyolefin composition of claim 1, wherein the stabilizer system comprises from 10 percent to 80 percent N, N-dialkylhydroxylamine and from 90 percent to 20 percent phosphite.

13. The composition; of polymer of claim 1, further comprising (c) at least one other stabilizing compound, the other stabilizing compound comprising at least one member selected from the group consisting of a phenol, a hindered amine and a phosphite other than 2, 2 ', 2"-nitrile [triethyl tris (3, 3', 5, 5 ', tetra-tert-butyl-1,1-biphenyl-2,2', diyl) phosphite] or tris (2, 4-di-tert-butylphenyl) phosphite.

The polyolefin composition of claim 13, wherein the other stabilizing compound is phosphite of 2,4,6-tri-tert-butylphenyl-2-butyl-2-ethyl-1,3-propanediol.

The polyolefin composition of claim 13, wherein the other stabilizing compound is a hindered amine that is selected from the group consisting of poly [6- [(1, 1, 3, 3-tetramethyl-butyl) amino-s -triazine 2,4-yl] 2,2,6,6-tetramethyl-4-piperindyl) immo] hexamethylene [(2,2,6,6-tetramethyl-4-piper-id? l) imino] and 1, 3, 5-triazine-2, 4, 6, -triamma-N, N "- [1,2-ethanediylbis [N- (3- [4,6-bis- (butyl-1, 2, 2, 6, 6-pentamethyl-4-piperidinyl) amine] propyl- [N, N-dibutyl-N, N-bis (1,2,2,6,6-pentamethyl-4-piperidinyl)

16. The composition polyolefin of claim 13, wherein the other stabilizing compound is a phenol selected from the group consisting of tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane and tetrakis [meth? le-3- (3 ', 5' -d? -ter-but? l-4 '-hydroxyphenyl) propionate] methane. -' 3?

17. The polymer composition of claim 1, wherein the olefin polymer is either a crystalline propylene homopolymer having an isotactic index greater than 90 or a random crystalline copolymer of propylene and either ethylene or a 1-olefin of 4 atoms of carbon to 10 carbon atoms.

18. The polymer composition of claim 1, wherein the olefin polymer is a vis-disintegrated polypropylene having a melt flow rate of 15 to 50 grams per 10 minutes, measured in accordance with the American Society for Testing. of Materials 1238, Condition L.

19. The polymer composition of claim 18, wherein the melt flow rate is 25 to 38 grams per 10 minutes, which is measured according to the American Society for Testing Materials 1238, Condition L.

20. A method for preparing an olefin polymer fiber or film, comprising (A) incorporating the following additives into an olefin polymer; (i) an acid neutralizing agent that is not a metal salt of a saturated or unsaturated fatty acid, (ii) a processing aid comprising a metal salt of a saturated or unsaturated fatty acid, the metal salt of a saturated or unsaturated acid is present in a maximum amount of 200 parts per million, (lii) a stabilizing system that comprises (a) a phosphite which is selected from the group consisting of 2, 2 ', 2"-nitrile [triethyl-tris (3, 3', 5,5 ', tetra-tert-butyl-1, 1-biphenyl) -2, 2 ', diyl) phosphite] and tris (2, -di-tert-butylphenyl) phosphite; and (b) an N, N-dialkylhydroxylamine, thereby producing a stabilized polyolefin polymer; and (B) extruding the stabilized olefin polymer through a matrix, thereby producing an olefin polymer fiber or film.

21. A fiber produced in accordance with the process of claim 20.

22. A film produced in accordance with the process of claim 20.

23. A fabric comprising a plurality of fibers of claim 21.

24. The fabric of Claim 23, wherein the fabric is a non-woven fabric prepared using a meltblown or meltblown process.