SK127295A3 - Stabilized polypropylene fiber and increasing method of resistance and heat stability of polypropylene fiber - Google Patents

Abstract

Blends of long chain N,N-dialkylhydroxylamines, selected phosphites and selected hindered amines are surprisingly effective in providing processing, long term heat aging and light stability performance and especially gas fade resistance to polypropylene fibers in the absence of a traditionally used phenolic antioxidant.

Description

A stabilized polypropylene fiber and a method of increasing the resistance and thermal stability of a polypropylene fiber

Technical field m / nes i o

The invention relates to a stabilized polypropylene fiber, containing or substantially free of any conventionally used phenolic antioxidant, with increased light stability, increased long-term thermal stability, and in particular increased resistance to fading by gases. This fiber is stabilized with an effective amount of a mixture of selected hindered amine, selected hydroxylamine, and selected phosphite.

BACKGROUND OF THE INVENTION

The polypropylene fiber is typically stabilized with a mixture of a selected phenolic antioxidant, a selected phosphite, and a selected light stabilizer containing hindered amine residues. This formulation generally exhibits adequate processing and stabilization properties against the effects of heat and light, but does not exhibit the adequate resistance to gas fading necessary to maintain color properties during storage and end use. There is a long-felt need in the market for a stabilized system that can prevent this gas fading and color formation associated with the use of phenolic antioxidants. Gas fading is known in the art as a discoloration due to exposure of plastic products to the atmosphere containing nitrogen oxides.

SUMMARY OF THE INVENTION

The components of the proposed stabilizer system for polypropylene fibers are generally well known as stabilizers for a variety of organic and polymeric substrates. The components of this polypropylene fiber stabilizer system are a specific combination selected in the form of the 2,2,6,6-tetramethylpiperidine group of the hindered amines, phosphites or phosphonites, and Ν, dial-dialkylhydroxylamines, in the absence or substantially absence of a phenolic antioxidant. This stabilizer formulation imparts to polypropylene fibers, which are well known to be difficult to stabilize effectively, unexpectedly good resistance to gas fading and heat and light stability properties. This stabilizer system without phenolic antioxidant shows the best polypropylene fiber. Changing fibers using stabilizer systems containing phenolic antioxidants when exposed to an atmosphere containing nitrogen oxides, i. conditions for gas fading, make such systems unacceptable with respect to this significant property, although phenolic antioxidants act accordingly.

overall stabilization of polypropylene color

Defended amines represent a very important group of light and heat stabilizers based on compounds containing some 2,2,6,6-tetramethylpiperidine moiety in the molecule. These compounds have achieved great commercial success and are well known in the art.

Similarly, phosphonites and phosphites, such as those described in US-A-4,360,617, have also achieved great commercial success as stabilizers.

Ν, Ν-dialkylhydroxylamines are also known in the art, as can be found in US-A-4 590 231, US-A-4 782 105, US-A-4 876 300 and US-A-4 013 510. These compounds are useful as processing stabilizers for polyolefins when used alone or in combination with phenolic antioxidants and / or other auxiliary additives, in particular as disclosed in US-A-4 876 300. Although US-A-4 876 300 generally discloses that Ν, Ν-dialkylhydroxylamines can be used in combination with phenolic antioxidants, amine-defended, phosphite, UV-absorbing and other additives, it is not specifically described that polypropylene fibers can be effectively stabilized by specific combinations of selected hindered amines, phosphites or phosphonites and N, N-dialkylhydroxylamines. Thus, the present invention is essentially selected from the broad general scope of US-A-4,876,300.

The compositions of the invention differ from those known in the art in several important aspects, listed below:

1. combinations of hindered phenolic antioxidants with phosphites generally show very poor resistance to gas fading;

2. the phosphites themselves do not have adequate efficiency for processing stabilization and thermal stabilization; and

3. hindered amine phosphites do not have adequate processing stabilization.

The combination of stabilizers provides all of the desired properties of gas fading resistance, processing stability, and thermal stability.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stabilizer system for polypropylene fibers, in the absence of any commonly used phenolic antioxidant or in the presence of very low concentrations of phenolic antioxidant, which allows the polypropylene fibers to have enhanced light and long term stability. against gas fading, while maintaining stabilization during processing comparable to any systems using phenolic antioxidants.

It is a further object of the present invention to provide a method of improving resistance to gas fading and reducing dye formation in polypropylene fibers using said stabilizer system without a phenolic antioxidant.

The invention relates to a stabilized polypropylene fiber, containing or substantially free of any phenolic antioxidant, with improved light stability, increased long-term thermal stability and increased resistance to gas fading, wherein the fiber is stabilized with a mixture of:

(a) a hindered amine selected from the group consisting of polycondensation product of 4,4'-hexamethylenebis (amino-2,2 _of 6,6-tetramethylpiperidine) and 2,4-dichloro-6-tertioctylamino-s-triazine, polycondensation product 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid,

N, N ', N' ', N' '' - tetrakis [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s-triazine-2-yl ] -1,10-diamino-4,7-diazadecane, polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-morpholino-s-triazine, poly [methyl-3- (2,2,6,6-tetramethylpiperidin-4-yloxy) propyl] -siloxane bis (2,2,6,6-tetramethylpiperidin-4-yl) cyclohexylenedioxydimethylmalonate,

1,3,5-tris (N-cyclohexyl-N- [2- (2,2,6,6-tetramethylpiperazin-3-yl-4-yl) ethyl] amino) -s-triazine polycondensation product 4,4 ' -hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-cyclohexylamino-striazane, and poly (N- [4,6-bis (butyl- (2,2,6,6) -tetramethylpiperidin-4-yl) amino-5-triazin-2-yl] -1,4,7-triazanonan-omega-N '- [4,6-bis (butyl- (2,2,6, 6-tetramethylpiperidin-4-yl) amino) -s-triazine £-2-yl] -amine,

(b) a phosphite or phosphonite selected from the group consisting of tris (2,4-di-tert-butylphenyl) phosphite,

3,9-di (2,4-ditert-butylphenyl) -2,4,8,10-3,9-difosfa- [5.5] undecane,

2,2 ', 2-nitrilo-tris [ethyl (3,3', 5,5'-tetrater-butyl-1,1'-biphenyl-2,2'-diyl) phosphite], ethyl-bis (2,4 - di-tert-butyl-6-methylphenyl) phosphite, and tetrakis (2,4-di-tert-butylphenyl) -4,4'-bis (diphenylene) phosphonite, and

c) a hydroxylamine selected from the group consisting of

N, N-dioctadecylhydroxylamine,

Ν, Ν-dialkylhydroxylamine of the general formula T ^{: L} T ² NOH, where T ¹ and T ² represent a mixture of alkyl groups present in the amine of hydrogenated tallow, and

Ν, Ν-dialkylhydroxylamine product produced by direct oxidation of ínu, Ν-disubstituted amine tallow, with a weight ratio of components (a): (b): (c) ranging from 1: 1: 1 to 100: 2: 1, with preferably 10: 1: 1 to 10: 2: 1 and most preferably 6: 1: 1 to 6: 2: 1.

An effective amount of the stabilizer mixture is, for example, from 0.05 to 5%, preferably 0.1 to 2%, most preferably 0.15 to 1% by weight, based on the weight of the fiber.

The stabilized polypropylene fibers of particular interest are those in which component (a) is selected from the group consisting of the polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro -6-tert-octylamino-s-triazine, a product of polycondensation of 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid,

N, N ', N'',N' ^{, z} -tetrakis- [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s-triazin-2-yl ] -1,10-diamino-4,7-diazadecane, polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-morpholino-s-triazine, poly [methyl-3- (2,2,6,6-tetramethylpiperidin-4-yloxy) propyl] -siloxane, bis (2,2,6,6-tetramethylpiperidin-4-yl) cyclohexylenedioxydimethylmalonate, and

1,3,5-tris (N-cyclohexyl-N- [2- (2,2,6,6-tetramethylpiperazin-3-όη-4-yl) ethyl] amino) -s-triazine.

The stabilized polypropylene fibers, which are also of particular interest, are those in which component (b) is selected from the group consisting of tris (2,4-di-tert-butylphenyl) phosphite,

3,9-di (2,4-ditert-butylphenyl) -2,4,8,10-3,9-difosfa- [5.5] undecane,

2,2 ', 2' '- nitrilo-tris [ethyl (3,3', 5,5'-tetrater-butyl-1,1'-biphenyl-2,2'-diyl) phosphite], and ethyl-bis (2,4-ditert-butyl-6-methylphenyl) phosphite.

The stabilized polypropylene fibers of particular interest are those in which component (c) is a Ν, Ν-dialkylhydroxylamine product produced by the direct oxidation of the amine Ν, ub-disubstituted with the residues of a hydrogerial tallow.

Furthermore, the invention also relates to a binary stabilizer system wherein a polypropylene fiber, containing or substantially free of any phenolic antioxidant, is stabilized with enhanced light stability, increased long term thermal stability, and increased gas fading resistance stabilized by a mixture of:

(I) a hindered amine selected from the group consisting of the polycondensation product of 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid;

N, N ', N'',N' ^of '-tetrakis- [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s-triazin-2-yl ] -1,10-diamino-4,7-diazadecane, polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-morpholino-s-triazine, poly [methyl-3- (2,2,6,6-tetramethylpiperidin-4-yloxy) propyl] -siloxane bis (2,2,6,6-tetramethylpiperidin-4-yl) cyclohexylenedioxydimethylmalonate,

1,3,5-tris (N-cyclohexyl-N- [2- (2,2,6,6-tetramethylpiperazin-3-yl-4-yl) ethyl] amino) -s-triazine, and the polycondensation product 4, 4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-cyclohexylamino-s-triazine, and

II) a hydroxylamine selected from the group consisting of

N, N-dioctadecylhydroxylamine,

Ν, Ν-dialkylhydroxylamine of the formula T ^X T ² NOH, where T ^x and T ² are a mixture of alkyl groups present in the amine of hydrogenated tallow, and

The Ν, Ν-dialkylhydroxylamine product produced by direct oxidation of the Ν, Ν-disubstituted amine tallow by the method of US-A-5,013,510 or US-A-4,898,901, wherein the weight ratio of components (I): (II) ranges from 100: 1 to 1: 2, preferably 10: 1 to 1: 1 and most preferably: 1 to 3: 1.

Binary stabilized polypropylene fibers of particular interest are those in which component (I) is selected from the group consisting of the polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4- dichloro-6-tert-octylamino-s-triazine, a product of polycondensation of 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, and

N, N ', N'',N' ^{, z} -tetrakis- [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s-triazin-2-yl ] -1,10-diamino-4,7-diazadecane.

Binary stabilized polypropylene fibers of particular interest are those in which component (II) is a Ν, Ν-dialkylhydroxylamine product produced by direct oxidation of the amine Ν, dis-disubstituted with hydrogenated tallow residues according to US-A-5,013,510 or US- A-4 898 901

The effective amount of the stabilizer mixture is from 0.05 to 5%, preferably 0.1 to 2%, most preferably 0.15 to 1% by weight, based on the weight of the fiber.

The invention encompasses a selected mixture of stabilizers that is free of or substantially free of phenolic antioxidants. Some polypropylene manufacturers add small amounts, usually less than 0.01% by weight. phenolic antioxidant, aiding the start of production of the polypropylene resin. The amount of phenolic antioxidant remaining in the resin used to make the polypropylene fiber is much less than 0.05 wt%. phenolic antioxidant as used in the examples of US-A-4,876,300. Thus, the term containing or substantially free of phenolic antioxidant as used in the context of the invention means that 0 to 0.01% may be present in the compositions of the invention materials. phenolic antioxidant. No phenolic antioxidant is intentionally added to the compositions of the invention to achieve the described stabilizing effects.

Another very important embodiment of the invention is a method of improving gas fading resistance and reducing color formation in a stabilized polypropylene fiber by incorporating into the fiber an effective stabilizing amount of the stabilizer mixture described above without losing any other stabilizing property.

Yet another embodiment of the invention is a method of improving the resistance of a polypropylene fiber to degradation due to exposure to UV radiation, as compared to the resistance that can be achieved using the stabilizers themselves by incorporating into the fiber an effective stabilizing amount of the stabilizer mixture described above.

Yet another embodiment of the invention is a method of improving the thermal stability of a polypropylene fiber as compared to the stability that can be achieved using conventional stabilizers alone by incorporating into the fiber an effective stabilizing amount of the stabilizer mixture described above.

Said hindered amines and phosphites are commercially available or can be prepared by published methods.

The Ν, Ν-dialkylhydroxylamines are prepared according to the methods described in US-A-4 782 105, US-A-4 898 901 and in particular US-A-5 013 510 by direct oxidation of the amine N, N-disubstituted with hydrogenated tallow residues with hydrogen peroxide.

The polypropylene fiber may also contain other additives such as fillers and reinforcing agents such as calcium carbonate silicates, glass fibers, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon black, graphite, and other additives such as plasticizers, lubricants, emulsifiers, pigments, optical brighteners, flame retardants and antistatic agents.

Conventional antioxidant with or phosphite stabilization systems such as phenol phosphite and hindered amine as stabilizer, with hindered amine as stabilizer can achieve excellent stabilization of polypropylene fibers in selected areas, but all important properties of stabilized polypropylene fibers can only be optimized by using a tertiary combination selected hindered amine, selected hydroxylamine, and selected phosphite.

Polypropylene is widely used for the production of fibers for home, commercial and automotive carpeting. White or light colored fibers may change color due to fading by gases. The polypropylene resin as originally produced may contain very low concentrations of phenolic antioxidant for stabilization until the resin is later processed into fibers. In any case, additional stabilizers must be added to the propylene resin before fiber production is possible. Defended phenolic antioxidants are known to be a strong source of such a color change, due to the formation of quinone-type chromophores as oxidation products or as a result of exposure to nitrogen oxides (color change known as gas fade ”J).

Thus, it is desirable to remove the phenolic antioxidant component from the polypropylene fiber. When this has been done in a short time, other properties related to the stability of the polymer have been adversely affected. Phenol antioxidants protect the extrusion and fiberising polymer Phenol antioxidants further during melt processing, high temperature operations, protect the granulated polymer and the resulting fiber during storage and end use.

It has surprisingly been found that in the stabilizer system of the invention, which is a ternary combination of a selected hindered amine, a selected hydroxylamine and a selected phosphite, or a binary combination of a selected hindered amine and a selected hydroxylamine, the phenolic antioxidant can be replaced. The system results in a stability greater than that obtained with conventional stabilizer systems containing a phenolic antioxidant as a component without altering the color associated with the phenolic antioxidants upon exposure of the stabilized polypropylene fiber to the conditions. fading, i. atmosphere containing nitrogen oxides.

The following examples are given by way of illustration only and are not intended to limit the nature and scope of the invention in any way.

DETAILED DESCRIPTION OF THE INVENTION

Compounds used in the tests:

AO A = 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate

HALS 1 = polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-tert-octylamino-s-triazine,

HALS 2 = polycondensation product of 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid,

HALS 3 = N, Ν ', N' ', N ---- tetrakis- [4,6'-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s-triazine 2-yl], io-diamino-4,7-diazadecane,

HALS 4 = polycondensation product of 4,4'-hexa: methylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-morpholino-s-triazine,

HALS 5 = poly [methyl-3- (2,2,6,6-tetramethylpiperidin-4-yloxy) propyljsiloxane,

HALS 6 = bis (2,2,6,6-tetramethylpiperidin-4-yl) cyclohexylenedioxydimethyl malonate,

HALS 7 = 1,3,5-tris (N-cyclohexyl-N- [2- (2,2,6,5-tetramethylpiperazin-3-one-4-yl) ethyl] amino) -s-triazine

Fos I = tris (2,4-di-tert-butylphenyl) phosphite,

Fos II = 3,9-di (2,4-di-tert-butylphenyl) -2,4,8,10-tetraoxa-3,9-diphospha [5,5] undecane,

Fos III = 2,2 ', 2' ^of -nitrilo-tris [ethyl (3,3 ', 5,5'-tetrater-butyl-1,1'-biphenyl-2,2'-diyl) phosphite],

Fos IV = ethyl-bis (2,4-di-tert-butyl-6-methylphenyl) phosphite, a

HA A = Ν, Ν-dialkylhydroxylamine product produced by direct oxidation of ínu, Ν-disubstituted amine tallow by the method of US-A-5,013,510 or US-A-4,898,901,

All additives are given in weight percent based on polypropylene. All formulations also contain 0.05% by weight. calcium stearate.

Example 1

Stabilization of polypropylene fiber during processing

Polypropylene of a quality suitable for the manufacture of fibers containing 0,05% by weight. calcium stearate, dry blended with the test additives and then processed to granules at a melting point of 246 ° C. The granulated resin, which already contains all of the ingredients, is then made at 274 ° C using a laboratory model extruder for the production of fibers (Hills). The made 41 yarn yarn is stretched with a tension ratio of 1: 3.2 to give a final denier of 615/41.

ASTM 1238-86 determines the melt flow rates of formulated granules prior to fiber production and the yarn produced to form fibers. The less distant the melt flow indexes before and after the fiber production, the more efficient the stabilization in processing with the stabilizer system. Processing stability data are shown in Tables 1, 2, 3 and 4 below.

Table 1

stabilizer number melt flow index granules fiber HALS 1 0,30% Fos I 0.09% 15.4 20.7 HA A 0.01% HALS 1 0,30% FOS I 0.05% 14.9 19.6 HA A 0.05%

Continuation of Table 1

stabilizer number melt flow index Granules fiber HALS 1 0.05% Fos I 0.09% 13.6 17.7 HA A 0.01% HALS 1 0.05% FOS I 0.05% 13,6 18,8 HA A 0.05% AO A 0.05% HALS 1 0.05% 14,3 19,3 FOS I 0.05% HA A 0.05%

Table 2

stabilizer number melt flow index granules fiber HALS 2 0,30% Fos I 0.09% 13.7 18.6 HA A 0.01% HALS 2 0,30% Fos I 0.05% 13.8 18.3 HA A. 0.05%

Continuation of Table 2

stabilizer number melt flow index granules fiber HALS 2 0.05% Fos I 0.09% 13.4 17.8 HA A 0.01% HALS 2 0.05% Fos I 0.05% 14.4 18.7 HA A 0.05% AO Á 0.05% HALS 2 0.05% 12.9 18.1 FOS I 0.05% HA A 0.05%

Table 3

stabilizer number melt flow index granules fiber HALS 3 0,30% Fos I 0.09% 13.3 19.3 HA A 0.01% HALS 3 0,30% Fos I 0.05% 14.2 17.5 HA A, 0.05%

Continuation of Table 3

stabilizer number melt flow index granules fiber HALS 3 0.05% Fos I 0.09% 14.3 18.6 HA A 0.01% HALS 3 0.05% Fos I 0.05% 13.7 18.4 HA A 0.05% AO A 0.05% HALS 3 0.05% 12.8 17.5 Fos I 0.05% HA A 0.05%

Table 4

stabilizer number melt flow index granules fiber HALS 2 0.05% Fos II 0.05% 12.7 16.9 HA A 0.05% AO A 0.05% HALS 3 0.05% 12.9 16.2 Fos I. 0.05% HA A 0.05%

Examining the above data, it can be found that the formulations of the invention containing selected hindered amines, phosphites and hydroxylamines exhibit excellent processing stabilization of polypropylene that is comparable to stabilizer systems containing phenolic antioxidants.

Example 2

Stabilization of polypropylene fiber during processing

Differences in melt flow caused by insufficient processing stability may be even more evident when polypropylene fibers are produced under stricter processing conditions. In Example 1, polypropylene fibers are produced at a temperature of 274 ° C. However, it is not uncommon for polypropylene fibers to be produced at a much higher temperature of 302 ° C. The melt flow values of the polypropylene from which the fibers were made at such temperatures are shown in Tables 5, 6, 7 or 8 below.

Table 5

stabilizer number melt flow index fiber produced at 274 ° C fiber produced at 302 ° C Fos I 0.15% 14.6 26.9 Fos I 0,10% 13.3 15.5 AO A 0.05% Fos I 0.05% 12.7 16.1 AO A 0.05% FOS I 0,10% 13.5 16.2 HA A 0.05%

Continuation of Table 5 stabilizer number melt flow index fiber production- fiber vyrába- at 274 ° C n pri pri 302 DEG HALS 2 0.05% 15.7 31.9 Fos I 0,10% HALS 2 0.05% Fos I 0,10% 14.3 16.3 AO A 0.05% HALS 2 0.05% Fos I 0.05% 13.7 17.4 HA A 0.05% HALS 2 0.05% FOS I 0,10% 13.6 16.1 HA A 0.05% Table 6 stabilizer number melt flow index fiber production- fiber vyrába- at 274 ° C n pri pri 302 DEG Fos II 0.15% 13.7 20.1 Fos II 0,10% 13.0 16.5 AO A 0.05% HALS 2 0.05% 15.2 22.2 FOS II 0,10%

Continuation of Table 6

stabilizer number melt flow index fiber produced at 274 ° C fiber produced at 302 ° C HALS 2 0.05% Fos II 0,10% 12.2 15.5 AO A 0.05% HALS 2 0.05% Fos II 0.05% 12.4 15.5 HA A 0.05% HALS 2 0.05% Fos II 0,10% 12.7 15.6 HA A 0.05%

Table 7 stabilizer number melt flow index fiber produced at 274 ° C fiber produced at 302 ° C Fos I 0.15% 14.6 26.9 Fos I 0,10% 13.3 15.5 AO A 0.05% HALS 3 0.05% 14.8 31.4 Fos I 0,10%

Continuation of Table 7

stabilizer number melt flow index fiber produced at 274 ° C fiber produced at 302 ° C HALS 3 0.05% Fos I 0,10% 13.5 15.1 AO A 0.05% HALS 3 0.05% Fos I 0.05% 12.4 16.9 HA A 0.05% HALS 3 0.05% FOS I 0,10% 12.9 16.7 HA A 0.05%

Table 8

stabilizer number melt flow index fiber produced at 274 ° C fiber produced at 302 ° C Fos II 0.15% 13.7 20.1 Fos II 0,10% 13.0 16.5 AO A 0.05% HALS 3 0.05% 14.1 22.8 Fos II 0,10%

Continuation of Table 8

stabilizer number melt flow index fiber produced at 274 ° C fiber produced at 302 ° C HALS 3 0.05% Fos II 0.05% 13.1 14.9 HA A 0.05% HALS 3 0.05% Fos II 0,10% 12.5 15.4 HA A 0.05%

The data in Tables 5, 6, 7 and 8 clearly indicate that in conventional stabilizer systems, the combination of phenolic antioxidant and phosphite provides good processing stability. Removal of the phenolic antioxidant in the presence or absence of the hindered amine results in a significant deterioration in processing stabilization. However, replacing the phenolic antioxidant with hydroxylamine results in processing stabilization quite comparable to that induced by the phenolic antioxidant phosphite system.

However, as can be seen from Example 5, the presence of a phenolic antioxidant in stabilizer systems has a deleterious effect on gas fading resistance.

Example 3

Stabilization of polypropylene fiber against the effects of light

The fibers are also exposed to UV light and long-term thermal aging under standard conditions.

Socks knitted from stabilized polypropylene fibers are exposed in an Atlas Xenon-Arc-Weather-Ometer using SAE J1885 Interior Automotive conditions at 89 ° C, 0.55 kW / cm ² at 340 nm without a spray cycle. The failure in this test is determined by observing the physical failure of the sock when it is scratched by a blunt glass rod. The longer it takes for a catastrophic failure to occur, the more effective the stabilizer system is. The days to break are shown in Tables 9, 10, 11 and 12 below for each of the stabilizer systems.

Table 9

stabilizer number days to violation in WeatherOmetr HALS .1 0,30% Fos I 0.09% 34 HA A 0.01% HALS 1 0,30% Fos I 0.05% 38 HA A 0.05% HALS 1 0,30% AO A 0.05% 38 Fos I 0.05% HA A 0.05% HALS 1 0,30% AO A 0.05% 28 Fos I 0,10%

Table 10

stabilizer number days to violation in WeatherOmetr HALS 2 0,30% Fos I 0.09% 23 HA A 0.01% HALS 2 0,30% Fos I 0.05% 30 HA A 0.05% Table 11 stabilizer number days to violation in WeatherOmetr HALS 3 0,30% Fos I 0.09% 38 HA A 0.01% HALS 3 0,30% Fos I 0.05% 37 HA A 0.05% Table 12 stabilizer number days to violation in WeatherOmetr HALS 2 0.05% FOS II 0.05% 9 HA A 0.05%

Example 4

Long-term thermal stability of polypropylene fiber

For long term heat aging at 120 ° C, other knitted socks of stabilized polypropylene fiber are exposed in an artifical furnace equipped with a rotating device. Again, the violation is determined as described above. The longer it takes for a substantial (catastrophic) breach to occur, the more effective the stabilizer system is. The data obtained in the tests are shown in Tables 13, 14 and 15 below.

Table 13

stabilizer number days to failure at 120 ° C HALS 1 0,30% Fos I 0.09% 65 HA A 0.01% HALS 1 0,30% Fos I 0.05% 61 HA A 0.05% Table 14 stabilizer number days to violation at 120 ° C HALS 2 0,30% Fos I 0.09% 40 HA A 0.01% HALS 2 0,30% FOS I 0.05% 72 HA A 0.05%

Table 15

stabilizer number days to violation at 120 ° C HALS 3 0,30% FOS I 0.09% 68 HA A 0.01% HALS 3 0,30% Fos I 0.05% 75 HA A 0.05%

Examples 5-6 show that, as far as gas fading resistance is concerned, the stabilizer composition of the invention is much better when measuring delta E values where low numbers mean less color. The numerical differences are significant and the samples can be easily visually distinguished.

Example 5

Resistance to gas fading or color stability of polypropylene fiber

Other knitted polypropylene fiber socks are exposed to nitrogen oxides in the Exposure Chamber using the AATCC Test Method 23-1988 Colorfastness to Burnt Gas Fumes for 3 to 7 cycles. The test samples are removed from the chamber and the color change (delta E color scale) determined on an Applied Color Systems Model CS-5 colorimeter (light source D65, observer 2 °). Low Delta E values indicate less color and better stabilization. The data obtained in the tests are shown in Tables 16, 17, 18, 19, 20, 21 and 22 below.

Table 16

stabilizer number delta E colors after the cycle 3 7 HALS 1 0,30% Fos I 0.09% 2,4 2,8 HA A 0.01% HALS 1 0,30% FOS I 0.05% 2,3 2,9 HA A 0.05% HALS 1 0,30% AO A 0.05% 5.7 6.7 FOS I 0.09% HA A 0.01% HALS 1 0,30% AO A 0.05% 4.3 6.1 Fos I 0.05% HA A 0.05%

Table 17

stabilizer number delta E colors after the cycle 3 7 HALS 1 0.05% Fos I 0.09% 1,9 1,5 HA A 0.01% HALS 1 0.05% Fos I 0.05% 1,8 1,9 HA A 0.05%

Continuation of Table 17

stabilizer number delta E colors after the cycle 3 7 HALS 1 0.05% AO A 0.05% 3.8 5.2 Fos I 0.09% HA A 0.01% HALS 1 0.05% AO A 0.05% 3,2 5 Fos I 0.05% HA A 0.05%

Table 18

stabilizer number delta E colors after the cycle 3 7 HALS 2 0,30% Fos I 0.09% 1,6 1,5 HA A 0.01% HALS 2 0,30% Fos I 0.05% 1,5 1,9 HA A 0.05% HALS 2 0,30% AO A 0.05% 3,9 5,3 Fos I ' 0.09% HA A 0.01%

Continuation of Table 18

stabilizer number delta E colors after the cycle 3 7 HALS 2 0,30% AO A 0.05% 1.9 3.7 FOS I 0.05% HA A 0.05% Table 19 stabilizer number delta E colors after the cycle

7

HALS 2 0.05% Fos I 0.09% 1.6 1.5 HA A 0.01% HALS 2 0.05% Fos I 0.05% 1.0 1.3 HA A 0.05% HALS 2 0.05% AO A 0.05% 3.8 4.9 Fos I 0.09% HA A 0.01% HALS 2 0.05% AO A 0.05% 2.0 3.9 Fos I 0.05% HA A 0.05%

Table 20

stabilizer number delta E colors after the cycle 3 7 HALS 3 0,30% Fos I 0.09% 2.4 2.3 HA A 0.01% HALS 3 0,30% Fos I 0.05% 1.7 1.9 HA A 0.05% HALS 3 0,30% AO A 0.05% 4.8 6.7 Fos I 0.09% HA A 0.01% HALS 3 0,30% AO A 0.05% 3.1 5.3 Fos I 0.05% HA A 0.05% Table 21 stabilizer number delta E colors after the cycle 3 7 HALS 3 0.05% FOS I 0.09% 1.9 1.6 HA A 0.01% HALS 3 0.05% Fos I 0.05% 1.2 1.3 HA A 0.05%

Continuation of Table 21

stabilizer number delta E colors after the cycle 3 7 HALS 3 0.05% AO A 0.05% 4.0 5.3 Fos I 0.09% HA A 0.01% HALS 3 0.05% AO A 0.05% 2,3 4,6 FÔS I 0.05% HA A 0.05%

Table 22 stabilizer number delta E colors after the cycle 3 7 HALS 2 0.05% Fos II 0.05% 1,5 1,8 HA A 0.05% HALS 2 0.05% AO A 0.05% 1,9 3,1 Fos II 0.05% HA A 0.05%

Example 6

Resistance to gas fading or color stability of polypropylene fiber

Other knitted socks of stabilized polypropylene fiber are exposed to nitrogen oxides in the Exposure Chamber using the AATCC Test Method 23-1988 Colorfastness to Burnt Gas Fumes for 3 cycles ”. Test samples are removed from the chamber and the color change (delta E color scale) determined on an Applied Color Systems Model CS-5 colorimeter (light source D65, observer 2 °). The data obtained in the tests are shown below in Tables 23, 24 and 25. Low delta E values indicate less color and better stabilization.

Table 23

stabilizer number delta E colors after cycle 3 HALS 1 0.15% Fos I 0.08% 6.9 AO A 0,04% HALS 1 0.15% FOS I 0.08% 2.4 HA A 0,04% HALS 4 0,30% FOS I 0,10% 2.7 AO A 0.05% HALS 4 0,30% Fos I 0.05% 1.2 HA A 0.05% HALS 5 0,30% FOS I 0,10% 3.2 HA A 0.05% HALS 5 0,30% Fos I 0.05% ! 0 HA A 0.05%

Continuation of Table 23

stabilizer number delta E colors after cycle 3 HALS 6 0,30% Fos I 0,10% 2.1 AO A 0.05% HALS 6 0,30% FOS I 0.05% 1.0 HA A 0.05% HALS 7 0,30% Fos I 0,10% 2.2 AO A 0.05% HALS 7 0,30% Fos I 0.05% 1.0 HA A 0.05%

Table 24

stabilizer number delta E colors after cycle 3 HALS 1 0.15% Fos III 0.08% 5.6 AO A 0,04% HALS 1 0.15% Fos III 0.08% 3.8 HA A 0,04%

Table 25

stabilizer number delta E colors after cycle 3 HALS 1 0.15% Fos IV 0.08% 4.8 AO A 0,04% HALS 1 0.15% Fos IV 0.08% 2.3 HA A 0,04%

Examination of the above data suggests that formulations of the invention that contain other selected hindered amines, other phosphites and hydroxylamines provide polypropylene excellent gas fading resistance and color stability, much better than stabilizer systems containing a phenolic antioxidant.

Example 7

Resistance to gas fading or color stability of polypropylene fiber

The method of Example 6 measures gas fading resistance or color stability of a polypropylene fiber if the fiber is protected by a binary stabilizer system containing a hindered amine and hydroxylamine in the absence of any phosphite, compared to a fiber further comprising a phenolic antioxidant. The data obtained in the tests are shown below in Tables 26, 27 and 28. Low delta E values indicate less color and better stabilization.

Table 26

stabilizer number delta E colors after cycle 3 HALS 1 0.05% FOS I 0,10% 4.7 AO A 0.05% HALS 1 0.05% 1.0 HA A 0,10% HALS 1 0.05% 1.2 HA A 0.05%

Table 27 stabilizer number delta E colors after cycle 3 HALS 2 0.05% FOS I 0,10% 4.1 AO A 0.05% HALS 2 0.05% 0.9 HA A 0,10% HALS 2 0.05% 0.9 HA A 0.05%

Table 28

stabilizer number delta E colors after cycle 3 HALS 3 0.05% Fos I 0,10% 4.4 AO A 0.05% HALS 3 0.05% 1.0 HA A 0,10% HALS 3 0.05% 0.9 HA A 0.05%

Examination of the above data suggests that the binary formulations of the invention that contain selected hindered amines and hydroxylamines provide polypropylene excellent gas fade resistance and color stability, far superior to stabilizer systems containing a phenolic antioxidant.

Example 8

Stabilization of polypropylene fiber during processing

The differences in the melt flow due to insufficient processing stability are quite evident when fibers are made of polypropylene under stringent processing conditions. In particular, they are evident when fibers are produced from polypropylene at a temperature of 302 ° C. The lower the melt indexes, the more efficient the stabilization in the stabilizer system processing (see also Example 1). The melt flow values of the polypropylene from which the fibers were made at this temperature are shown in Tables 29, 30 and 31 below.

Table 29

stabilizer number melt index of the fiber produced at 302 ° HALS 1 0.05% 65 HALS 1 0.05% 34 Fos I 0,10% HALS 1 0.05% Fos I 0,10% 16 AO A 0.05% HALS 1 0.05% Fos I 0.05% 18 HA A 0.05% HALS 1 0.05% 18 HA A 0.05% Table 3 0 stabilizer number melt flow index fiber produced at 302 ° HALS 2 0.05% 56 HALS 2 0.05% 24 Fos I 0,10% HALS 2 0.05% FOS I 0,10% 15 AO A 0.05%

Continuation of Table

stabilizer number melt flow index fiber produced at 302 ° HALS 2 0.05% FOS I 0.05% 19 HA A 0.05% HALS 2 0.05% 18 HA A 0.05% Table 31 stabilizer number melt flow index fiber produced at 302 ° HALS 3 0.05% 28 HALS 3 0.05% 31 Fos I 0,10% HALS 3 0.05% FOS I 0,10% 16 AO A 0.05% HALS 3 0.05% Fos I 0.05% 17 HA A 0.05% HALS 3 0.05% 17 HA A 0.05%

The data in Tables 29, 30 and 31 clearly indicate that in conventional stabilizer systems, the combination of phenolic antioxidant, hindered amine and phosphite provides good processing stability. Removal of the phenolic antioxidant results in a significant deterioration in processing stabilization. However, replacing the phenolic antioxidant with hydoxylamine results in processing stabilization quite comparable to the stabilization induced by the phenolic antioxidant phosphite system, both in the presence and absence of the phosphite component. Thus, the hindered amine plus hydroxylamine binary stabilizer system provides excellent stabilization in the heat treatment of the polypropylene fiber.

Claims (16)

PATENT CLAIMS A stabilized polypropylene fiber, containing or substantially free of any phenolic antioxidant, with increased light stability, increased long-term thermal stability and increased resistance to gas fading, characterized in that it is stabilized by a mixture (a) a hindered amine selected from the group consisting of polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-tert-octylamino-s-triazine, polycondensation product of 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, N, N ', N' ', N' '' - tetrakis [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s-triazine-2-yl] -1,10-diamino-4,7-diazadecane, polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-morpholino-s-triazine, poly [methyl-3- (2,2,6,6-tetramethylpiperidin-4-yloxy) propyl] -siloxane, bis (2,2,6,6-tetramethylpiperidin-4-yl) cyclohexylenedioxydimethylmalonate, 1,3,5-tris (N-cyclohexyl-N- [2- (2,2,6,6-tetramethylpiperazin-3-one-4-yl) ethyl] amino) -s-triazine polycondensation product 4, 4 ' hexamethylenebis (amino-2,2,6,640 tetramethylpiperidine) and 2,4-dichloro-6-cyclohexylamino-striazine, and poly (N- [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s) -triazin-2-yl] -1,4,7-triazanonan-oinega-N '- [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s triazin-2-yl] -amine, (b) a phosphite or phosphonite selected from the group consisting of tris (2,4-di-tert-butylphenyl) phosphite, 3,9-di (2,4-di-tert-butylphenyl) -2,4,8,10-tetraoxa-3,9-diphospha- [5,5-iodocane, 2,2 ', 2' '- nitrilotris [ethyl (3,3', 5,5'-tetrater-butyl-1,1'-biphenyl-2,2'-diyl) phosphite], ethyl bis (2,4 - di-tert-butyl-6-methylphenyl) phosphite, and tetrakis (2,4-di-tert-butylphenyl) -4,4'-bis (diphenylene) phosphonite, and c) a hydroxylamine selected from the group consisting of N, N-dioctadecylhydroxylamine, Ν, Ν-dialkylhydroxylamine of the general formula Τ Τ ΝΟΗ kde ΝΟΗ T, where T ¹ and T ² represent an amount of alkyl groups present in the amine of hydrogenated tallow, and Ν, Ν-dialkylhydroxylamine product produced by direct oxidation of ínu, Ν-disubstituted amine tallow, with a weight ratio of (a): (b): (c) of from 1: 1: 1 to 100: 2: 1 The stabilized fiber of claim 1, wherein component (a) is selected from the group consisting of polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6. - tert-octylamino-s-triazine, a product of polycondensation of 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, N, N ', N ^{"of the} N''' - tetrakis [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s-triazine-2-yl] -1,10-diamino-4,7-diazadecane, polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-morpholino-s-triazine, poly [methyl-3- (2,2,6,6-tetramethylpiperidin-4-yloxy) propyl] -siloxane, bis (2,2,6,6-tetramethylpiperidin-4-yl) cyclohexylenedioxydimethylmalonate, and 1,3,5-tris (N-cyclohexyl-N- [2- (2,2,6,6-tetramethylpiperazin-3-one-4-yl) ethyl] amino) -s-triazine. The stabilized fiber of claim 1, wherein component (b) is selected from the group consisting of tris (2,4-di-tert-butylphenyl) phosphite, 3,9-di (2,4-ditert-butylphenyl) -2,4,8,10-3,9-difosfa- [5.5] undecane, 2,2 ', 2' '- nitrilotris [ethyl (3,3', 5,5'-tetrater-butyl-1,1'-biphenyl-2,2'-diyl) phosphite], and ethyl-bis (2 , 4-tert-butyl-6-methylphenyl) phosphite. The stabilized fiber of claim 1, wherein component (c) is a Ν, Ν-dialkylhydroxylamine product made by direct oxidation of an N, N-disubstituted amine tallow residue. Stabilized fiber according to claim 1, characterized in that the weight ratio of components (a): (b): (c) is from 10: 1: 1 to 10: 2: 1 Stabilized fiber according to claim 1, characterized in that the amount of the stabilizer mixture is from 0.05 to 5% by weight, based on the weight of the fiber. A method of improving gas fading resistance and reducing color formation in a stabilized polypropylene fiber without loss of any other stabilizing property, characterized in that the stabilizer mixture of claim 1 is incorporated into the fiber. A method of improving the resistance of a polypropylene fiber to degradation due to exposure to UV radiation, as compared to the resistance that can be achieved using conventional stabilizers alone, characterized in that the stabilizer mixture of claim 1 is incorporated into the fiber. A method of improving the thermal stability of a polypropylene fiber as compared to that obtainable with conventional stabilizers alone, characterized in that a stabilizer mixture according to claim 1 is incorporated into the fiber. 10. Stabilized polypropylene fiber, containing or substantially free of phenolic antioxidant, with increased light stability, · increased long-term thermal stability and increased resistance to gas fading, characterized by being stabilized by the mixture (I) a hindered amine selected from the group consisting of the polycondensation product of 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid; N, N ', N ^{"of the} N''' - tetrakis [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s-triazine-2-yl] -1,10-diamino-4,7-diazadecane, polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-morpholino-s-triazine, poly [methyl-3- (2,2,6,6-tetramethylpiperidin-4-yloxy) propyl] -siloxane, bis (2,2,6,6-tetramethylpiperidin-4-yl) cyclohexylenedioxydimethylmalonate, 1,3,5-tris (N-cyclohexyl-N- [2- (2,2,6,6-tetramethylpiperazin-3-one-4-yl) ethyl] amino) -s-triazine, and polycondensation product 4, 4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-cyclohexylamino-s-triazine, and II) a hydroxylamine selected from the group consisting of N, N-dioctadecylhydroxylamine, Ν, Ν-dialkylhydroxylamine of the general formula Τ ^Χ Τ ² ΝΟΗ, where T ^x and T ² represent a mixture of alkyl groups present in the amine of hydrogenated tallow, and The Ν, Ν-dialkylhydroxylamine product produced by direct oxidation of the Ν, Ν-disubstituted amine tallow amine, wherein the weight ratio of components (I): (II) is from 100: 1 to 1: 2. Stabilized fiber according to claim 10, characterized in that component (I) is selected from the group consisting of the polycondensation product of 4,4'-hexamethylenebis (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6. - tert-octylamino-s-triazine, a product of polycondensation of 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, N, N ', N' ', N' '' - tetrakis [4,6-bis (butyl- (2,2,6,6-tetramethylpiperidin-4-yl) amino) -s-triazine-2-yl] -1,10-diamino-4,7-diazadecane. Stabilized fiber according to claim 10, characterized in that component (II) is an N, N-dialkylhydroxylamine product produced by direct oxidation of the N, N-disubstituted amine tallow residues. Stabilized fiber according to claim 10, characterized in that the weight ratio of components (I): (II) is from 10: 1 to 1: 1. The stabilized fiber of claim 10, wherein the amount of the stabilizer mixture is from 0.05 to 5% by weight based on the weight of the fiber. A method of improving resistance to fading by gases and reducing color formation in a stabilized polypropylene fiber without loss of any other stabilizing property, comprising incorporating into said fiber a mixture of stabilizers according to claim 10. A method of improving the resistance of a polypropylene fiber to degradation due to exposure to UV radiation, as compared to the resistance that can be achieved using conventional stabilizers alone, characterized in that a stabilizer mixture according to claim 10 is incorporated into the fiber.