Environmentally friendly processing aid based on oligomeric hindered amines

Abstract

The present invention relates to a use of an oligomeric hindered amine to improve the flow properties of a melt comprising a thermoplastic polymer; and to a process for improving the flow properties of a melt comprising a thermoplastic polymer, which comprises the step of incorporating an oligomeric hindered amine into the thermoplastic polymer prior to or during melt processing, where the thermoplastic polymer is free of a polymer processing aid.

Description

[0001] 231527 1 Environmentally friendly processing aid based on oligomeric hindered amines Description The present invention relates to a use of an oligomeric hindered amine to improve the flow properties of a melt comprising a thermoplastic polymer; and to a process for improving the flow properties of a melt comprising a thermoplastic polymer, which comprises the step of incorporating an oligomeric hindered amine into the thermoplastic polymer prior to or during melt processing, where the thermoplastic polymer is free of a polymer processing aid. The flow characteristics of polymer melts have paramount significance for the design and operating conditions ofindustrial processing equipment and may tremendously affect the overall properties of manufactured polymerarticles. Polymer melts typically exhibit a non-Newtonian behavior; i.e. their apparent viscosity is strongly dependent on the shear rate applied when processing polymers at temperatures well above their melt-ing points. High shearrates result typically from high levels of mechanical energy (pressure and shear) applied for the purpose of extruding,feeding or any sort of transporting polymer melts in the course of the shape-giving process. Furthermore, high shear rates may equally result from high flow rates or high flow velocities when polymer melts are forced to pass through narrow dies, nozzles, cylinder profiles and the like, which can be of round, rectangular, annular, slit-like, or any other irregular shape or low gap-width cross sections. If inadequate attention is paid to the peculiar rheological properties of polymer melts, this may eventually lead to several negative, and therefore undesired, consequences in the aesthetic or mechanical polymer properties, which are well known in extrusion processes, in particular in the manufacture of profiles, especially thin-walled profiles, cast or blown films. Various defects are commonly referred to as sharkskin, snake-skin or orange-peel. These terms are figurative and self-explanatory descriptions of melt fracture phenomena which become more and more apparent when high shear rates cause visible roughness or even cracks and crevices on the polymer surface, so that the optical and mechanical properties of the manufactured polymer article are heavily deteriorated. A particular case concerns polyolefins, among them linear polyethylene, such as linear low-density polyethylene (LLDPE), a widely applied commodity polymer but known for its difficult melt processability. Several polyolefins, especially LLDPE, are prone to melt fracture (MF) due to their relatively narrow molecular weight distribution and to the specific entanglement features of their polymeric chains. While there is consensus that fluorine-based polymers incorporated into LLDPE im-prove the appearance of extrudates at high output rates and reduce the polymer melt viscosity, these products are also known for several shortcomings, such as the long onset time until such processing aids perform as expected (i.e. until MF is eliminated or its occurrence postponed to significantly higher shear rates, and / or until the energy consumption for compounding at a given throughput gets significantly reduced). Purging, removing or cleaning after processing such polymers 231527 2 containing fluorine-based polymers is very time consuming, i.e. when passing from one production run to another one. In addition, such fluorine-based processing aids are often produced from the precursor perfluorooctaonic acid (PFOA) which appears to be very persistent in the environment and is suspected to be detrimental to the health. Apart from fluorine-based polymer processing aids, the use of silicone-based polymers or of polyethylene glycol, waxes or various fatty acid esters, is also known in the art. Not only are the benefits of such products not always prominent, as the performance at given concentration can be inferior to fluorine-based polymer processing aids and because they may not display their efficiency on all equipment. Silicone-based polymers or those based on polyethylene glycol present further drawbacks such as the apparition of undesired streaks in the final product, for instance in films, the development of fumes, or plate out on calendring rolls.The object was to overcome the above-mentioned drawbacks.The object was solved by a use of an oligomeric hindered amine to improve the flow properties of a melt comprising a thermoplastic polymer. The object was also solved by a process for improving the flow properties of a melt comprising a thermoplastic polymer, which comprises the step of incorporating an oligomeric hindered amine into the thermoplastic polymer prior to or during melt processing, where the thermoplastic polymer is free of a polymer processing aid, preferably free of a fluorine-based polymer. The improve flow property is preferably a reduced melt fracture. The reduced melt fracture can be analyzed visually, e.g. by analyzing the time until a shark-skin disappears from the surface of the melt. The oligomeric hindered amine may have a molecular weight of at least 1000 g / mol, preferably at least 1300 g / mol, and in particular at least 1500 g / mol.The oligomeric hindered amine may have a molecular weight of up to 20000 g / mol, up to 10000 g / mol, and inparticular up to 5000 g / mol.The melt may comprise 0.01 to 4 wt%, preferably 0.05 to 2 wt%, more preferably from 0.1 to 1.5 wt% and inparticular from 0.2 to 1.0 wt% of the oligomeric hindered amine.The oligomeric hindered amine comprises usually a compound selected from a compound of the formula (I) 231527 3 wherein b1is a number from 1 to 20; the radicals R1independently of one another are hydrogen, C1-C8alkyl, O., -OH, -CH2CN, C1-C18alkoxy, C5- C12cycloalkoxy, C3-C6alkenyl, C7-C9phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C1-C4alkyl; or C1-C8acyl; R2is C2-C18alkylene, C5-C7cycloalkylene or C1-C4alkylenedi(C5-C7cycloalkylene); R3 and R4 independently of one another are hydrogen, C1-C12alkyl, C5-C12cycloalkyl unsubstituted or substituted by 1, 2 or 3 C1-C4alkyl; phenyl unsubstituted or substituted by 1, 2 or 3 C1-C4alkyl; C7-C9phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C1-C4alkyl; or a group of the formula (Ia) orR3 and R4, together with the nitrogen atom to which they are linked, form a 5- to 10-membered heterocyclic ring;

[0002] 231527 4 and / or a compound of the formula (II) wherein b2 is a number from 1 to 20; the radicals X1 independently of one another are hydrogen, C1-C8alkyl, O., -OH, -CH2CN, C1-C18alkoxy, C5- C12cycloalkoxy, C3-C6alkenyl, C7-C9phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C1-C4alkyl; or C1-C8acyl; the radicals Y1independently of one another are hydrogen, C1-C12alkyl, C5-C12cycloalkyl unsubstituted or substituted by 1, 2 or 3 C1-C4alkyl; phenyl unsubstituted or substituted by 1, 2 or 3 C1-C4alkyl; C7-C9phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C1-C4alkyl; or a group of the formula (IIa); the radicals Z1 independently of one another are C2-C18alkylene, C5-C7cycloalkylene or C1-C4alkylenedi(C5- C7cycloalkylene). Examples of alkyl having up to 12 carbon atoms are methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert- butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methyl¬pentyl, 1,3-dimethyl¬butyl, n-hexyl, 1-methyl¬hexyl, n-heptyl, isoheptyl, 1,1,3,3-tetra¬methyl¬butyl, 1-methyl¬heptyl, 3-methyl¬heptyl, n-octyl, 2-ethyl¬hexyl, 1,1,3-tri¬methyl-hexyl, 1,1,3,3-tetra¬methyl¬pentyl, nonyl, decyl, undecyl, 1-methyl¬undecyl and dodecyl. Examples of alkoxy having up to 18 carbon atoms are methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, pentoxy, isopentoxy, hexoxy, heptoxy, octoxy, decyloxy, dodecyloxy, tetradecyloxy, hexadecyloxy and octadecyloxy. A preferred radical is n-propoxy. Examples of alkenyl having up to 6 carbon atoms are allyl, 2-methallyl, butenyl, pentenyl and hexenyl. Allyl is preferred. The carbon atom in position 1 is preferably saturated. Examples of C5-C12cycloalkyl unsubstituted or substituted by 1, 2 or 3 C1-C4alkyl are cyclohexyl, methylcyclohexyl and dimethylcyclohexyl. 231527 5 Examples of C5-C12cycloalkoxy are cyclopentoxy, cyclohexoxy, cycloheptoxy, cyclooctoxy, cyclodecyloxy and cyclododecyloxy. Cyclohexoxy is preferred. Examples of phenyl unsubstituted or substituted by 1, 2 or 3 C1-C4alkyl are methylphenyl, dimethylphenyl, trimethylphenyl and tert-butylphenyl. Examples of C7-C9phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C1-C4alkyl are methylbenzyl, dimethylbenzyl, trimethylbenzyl and tert-butylbenzyl. Examples of acyl containing not more than 8 carbon atoms are formyl, acetyl, propionyl, butyryl, pentanoyl, hexanoyl, heptanoyl, octanoyl, acryloyl, methacryloyl and benzoyl. C1-C8Alkanoyl, C3-C8alkenoyl and benzoyl are preferred. Examples of alkylene having up to 18 carbon atoms are ethylene, propylene, trimethylene, tetramethylene, pentamethylene, 2,2-dimethyltrimethylene, hexamethylene, trimethylhexamethylene and octamethylene. C2- C6alkylene, in particular hexamethylene is preferred. An example of C5-C7cycloalkylene is cyclohexylene. An example of C1-C4alkylenedi(C5-C7cycloalkylene) is methylenedicyclohexylene. A preferred example of a 5-to 7-membered heterocyclic ring is a morpholine group. The radicals R1 and X1 are preferably hydrogen, methyl or propoxy, in particular n-propoxy.Suitable compounds of component (I) and (II) are CHIMASSORB®944, CHIMASSORB®2020, CYASORB®UV 3346,CYASORB®UV 3529, DASTIB®1082, TINUVIN®NOR 371, TINUVIN®NOR 356, UVASORB®HA88 and CHIMASSORB®119.

[0003] 231527 6 Examples of the compounds of the formulae (I) and (II) are: wherein b1 is a number from 2 to 10, wherein b1 is a number from 1 to 10, wherein R1is hydrogen or methyl and b1is a number from 2 to 10, 231527 7 wherein b1is a number from 2 to 10, wherein b1is a number from 1 to 10, wherein b2is a number from 2 to 10, and . 231527 8 In one form the oligomeric hindered amine comprises a compound of the following formula (a) wherein b1 is a number from 1 to 10. Preferably, the compound of the formula (a) is the compound of the following formula (a1) In another form the oligomeric hindered amine comprises a compound of the following formula (b) In a particular preferred form the oligomeric hindered amine comprises the compound of the formula (a), preferablythe compound of the formula (a1). The oligomeric hindered amine may comprise a mixture of at least two different oligomeric hindered amines. 231527 9 Preferably, the oligomeric hindered amine comprises a mixture of two different oligomeric hindered amines, whereinone of the oligomeric hindered amines in the mixture comprises the compound of the formula (a), preferably thecompound of the formula (a1). In another preferred form, the oligomeric hindered amine comprises a mixture of two different oligomeric hinderedamines, wherein one of the oligomeric hindered amines in the mixture comprises the compound of the formula (a),andwhere the oligomeric hindered amines of the formula (a) and the other oligomeric hindered amine are present in aweight ratio of 30:1 to 1:2, 20:1 to 1:1, 15:1 to 2:1, or 12:1 to 4:1.In another preferred form, the oligomeric hindered amine comprises a mixture of two different oligomeric hindered amines, wherein one of the oligomeric hindered amines in the mixture comprises the compound of the formula (a1), and where the oligomeric hindered amines of the formula (a1) and the other oligomeric hindered amine are present in a weight ratio of 30:1 to 1:2, 20:1 to 1:1, 15:1 to 2:1, or 12:1 to 4:1. In particular, the oligomeric hindered amine comprises a mixture of two different oligomeric hindered amines, wherein one of the oligomeric hindered amines is of the formula (a) and the other is of the formula (b). In particular, the oligomeric hindered amine comprises a mixture of two different oligomeric hindered amines, wherein one of the oligomeric hindered amines is of the formula (a1) and the other is of the formula (b). In particular, the oligomeric hindered amine comprises a mixture of two different oligomeric hindered amines, wherein one of the oligomeric hindered amines is of the formula (a) and the other is of the formula (b), and where the oligomeric hindered amine of the formula (a) and the other oligomeric hindered amine of the formula (b) are present in a weight ratio of 30:1 to 1:2, 20:1 to 1:1, 15:1 to 2:1, or 12:1 to 4:1. In particular, the oligomeric hindered amine comprises a mixture of two different oligomeric hindered amines, wherein one of the oligomeric hindered amines is of the formula (a1) and the other is of the formula (b), and where the oligomeric hindered amine of the formula (a1) and the other oligomeric hindered amine of the formula (b) are present in a weight ratio of 30:1 to 1:2, 20:1 to 1:1, 15:1 to 2:1, or 12:1 to 4:1. In particular, the oligomeric hindered amine comprises a mixture of two different oligomeric hindered amines, wherein one of the oligomeric hindered amines is of the formula (a) and the other is of the formula (b), and where the oligomeric hindered amine of the formula (a) and the other oligomeric hindered amine of the formula (b) are present in a weight ratio of 20:1 to 1:1, preferably 15:1 to 2:1, and in particular 12:1 to 4:1. 231527 10 In particular, the oligomeric hindered amine comprises a mixture of two different oligomeric hindered amines, wherein one of the oligomeric hindered amines is of the formula (a1) and the other is of the formula (b), and where the oligomeric hindered amine of the formula (a1) and the other oligomeric hindered amine of the formula (b) are present in a weight ratio of 20:1 to 1:1, preferably 15:1 to 2:1, and in particular 12:1 to 4:1.Preferably the melt is free of fluorine-based polymers, such as per- and polyfluoroalkyl substances (also known asPFAS). Examples of fluorine-based polymers are elastomeric fluoropolymers (i. e. fluoroelastomers or amorphousfluoropolymers) and thermoplastic fluoropolymers (i. e. semi-crystalline fluoropolymers). Fluoroelastomers are fluoropolymers that are normally in the fluid state at room temperature and above, i. e. fluoropolymers which have Tg values below room temperature and which exhibit little or no crystallinity at room temperature. Fluorinated monomers which may be copolymerized to yield suitable fluoroelastomers include vinylidene fluoride, hexafluoropropylene, chlorotrifluoroethylene, tetrafluoroethylene and perfluoroalkyl perfluorovinyl ethers. Specific examples of the fluoroelastomers include copolymers of vinylidene fluoride and a comonomer selected from hexafluoropropylene, chlorotrifluoroethylene, 1-hydropentafluoropropylene, and 2hydropentafluoropropylene; copolymers of vinylidenefluoride, tetrafluoroethylene, and hexafluoropropylene or 1-or 2- hydropentafluoropropylene; and copolymers oftetrafluoroethylene, propylene and, optionally, vinylidene fluoride. Suitable semi-crystalline fluoropolymers are poly (vinylidene fluoride), homopolymers and copolymers of tetrafluoroethylene (such as Teflon FEP fluorocarbon resin, and copolymers of tetrafluoroethylene, propylene and, optionally, vinylidene fluoride).Examples of suitable thermoplastic polymers are:1. Polymers of monoolefins and diolefins, for example polypropylene, polyisobutylene, polybut-1-ene, poly-4- methylpent-1-ene, polyvinylcyclohexane, polyisoprene or polybutadiene, as well as polymers of cycloolefins, forinstance of cyclopentene or norbornene, polyethylene (which optionally can be crosslinked), for example highdensity polyethylene (HDPE), high density and high molecular weight polyethylene (HDPE-HMW), high density and ultrahigh molecular weight polyethylene (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), (VLDPE) and (ULDPE). Polyolefins, i.e. the polymers of monoolefins exemplified in the preceding paragraph, preferably polyethylene and polypropylene, can be prepared by different, and especially by the following, methods: a) radical polymerisation (normally under high pressure and at elevated temperature). b) catalytic polymerisation using a catalyst that normally contains one or more than one metal of groups IVb, Vb, VIb or VIII of the Periodic Table. These metals usually have one or more than one ligand, typically oxides, halides,alcoholates, esters, ethers, amines, alkyls, alkenyls and / or aryls that may be either ^- or ^-coordinated. These metalcomplexes may be in the free form or fixed on substrates, typically on activated magnesium chloride, titanium(III) 231527 11 chloride, alumina or silicon oxide. These catalysts may be soluble or insoluble in the polymerisation medium. The catalysts can be used by themselves in the polymerisation or further activators may be used, typically metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, said metals being elements of groups Ia, IIa and / or IIIa of the Periodic Table. The activators may be modified conveniently with further ester, ether, amine or silyl ether groups. These catalyst systems are usually termed Phillips, Standard Oil Indiana, Ziegler (-Natta), TNZ (DuPont), metallocene or single site catalysts (SSC). 2. Mixtures of the polymers mentioned under 1), for example mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (for example PP / HDPE, PP / LDPE) and mixtures of different types of polyethylene (for example LDPE / HDPE). 3. Copolymers of monoolefins and diolefins with each other or with other vinyl monomers, for example ethylene / propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene / but-1-ene copolymers, propylene / isobutylene copolymers, ethylene / but-1-ene copolymers, ethylene / hexene copolymers, ethylene / methylpentene copolymers, ethylene / heptene copolymers, ethylene / octene copolymers, ethylene / vinylcyclohexane copolymers, ethylene / cycloolefin copolymers (e.g. ethylene / norbornene like COC), ethylene / 1-olefins copolymers, where the 1-olefin is generated in-situ; propylene / butadiene copolymers, isobutylene / isoprene copolymers, ethylene / vinylcyclohexene copolymers, ethylene / alkyl acrylate copolymers, ethylene / alkyl methacrylate copolymers, ethylene / vinyl acetate copolymers or ethylene / acrylic acid copolymers and their salts (ionomers) as well as terpolymers of ethylene with propylene and a diene such as hexadiene, dicyclopentadiene or ethylidene-norbornene; and mixtures of such copolymers with one another and with polymers mentioned in 1) above, for example polypropylene / ethylene-propylene copolymers, LDPE / ethylene-vinyl acetate copolymers (EVA), LDPE / ethylene-acrylic acid copolymers (EAA), LLDPE / EVA, LLDPE / EAA and alternating or random polyalkylene / carbon monoxide copolymers and mixtures thereof with other polymers, for example polyamides. 4. Hydrocarbon resins (for example C5-C9) including hydrogenated modifications thereof (e.g. tackifiers) and mixtures of polyalkylenes and starch.Homopolymers and copolymers from 1.) - 4.) may have any stereostructure including syndiotactic, isotactic, hemi-isotactic or atactic; where atactic polymers are preferred. Stereoblock polymers are also included. 5. Polystyrene, poly(p-methylstyrene), poly(^-methylstyrene). 6. Aromatic homopolymers and copolymers derived from vinyl aromatic monomers including styrene, ^- methylstyrene, all isomers of vinyl toluene, especially p-vinyltoluene, all isomers of ethyl styrene, propyl styrene, vinyl biphenyl, vinyl naphthalene, and vinyl anthracene, and mixtures thereof. Homopolymers and copolymers may have 231527 12 any stereostructure including syndiotactic, isotactic, hemi-isotactic or atactic; where atactic polymers are preferred. Stereoblock polymers are also included. 6a. Copolymers including aforementioned vinyl aromatic monomers and comonomers selected from ethylene, propylene, dienes, nitriles, acids, maleic anhydrides, maleimides, vinyl acetate and vinyl chloride or acrylic derivatives and mixtures thereof, for example styrene / butadiene, styrene / acrylonitrile, styrene / ethylene (interpolymers), styrene / alkyl methacrylate, styrene / butadiene / alkyl acrylate, styrene / butadiene / alkyl methacrylate, styrene / maleic anhydride, styrene / acrylonitrile / methyl acrylate; mixtures of high impact strength of styrene copo- lymers and another polymer, for example a polyacrylate, a diene polymer or an ethylene / propylene / diene terpolymer; and block copolymers of styrene such as styrene / butadiene / styrene, styrene / isoprene / styrene, styrene / ethylene / butylene / styrene or styrene / ethylene / propylene / styrene. 6b. Hydrogenated aromatic polymers derived from hydrogenation of polymers mentioned under 6.), especially including polycyclohexylethylene (PCHE) prepared by hydrogenating atactic polystyrene, often referred to as polyvinylcyclohexane (PVCH). 6c. Hydrogenated aromatic polymers derived from hydrogenation of polymers mentioned under 6a.). Homopolymers and copolymers may have any stereostructure including syndiotactic, isotactic, hemi-isotactic or atactic; where atactic polymers are preferred. Stereoblock polymers are also included. 7. Graft copolymers of vinyl aromatic monomers such as styrene or ^-methylstyrene, for example styrene on polybutadiene, styrene on polybutadiene-styrene or polybutadiene-acrylonitrile copolymers; styrene and acrylonitrile (or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and methyl methacrylate on polybutadiene; styrene and maleic anhydride on polybutadiene; styrene, acrylonitrile and maleic anhydride or maleimide on polybutadiene; styrene and maleimide on polybutadiene; styrene and alkyl acrylates or methacrylates on polybutadiene; styrene and acrylonitrile on ethylene / propylene / diene terpolymers; styrene and acrylonitrile on polyalkyl acrylates or polyalkyl methacrylates, styrene and acrylonitrile on acrylate / butadiene copolymers, as well as mixtures thereof with the copolymers listed under 6), for example the copolymer mixtures known as ABS, MBS, ASA or AES polymers.8. Chlorine-containing polymers such as polychloroprene, chlorinated rubbers, chlorinated copolymer of isobutylene-isoprene (halobutyl rubber), chlorinated or sulfochlorinated polyethylene, copolymers of ethylene and chlorinatedethylene, epichlorohydrin homo- and copolymers, especially polymers of chlorine-containing vinyl compounds, forexample polyvinyl chloride, polyvinylidene chloride, as well as copolymers thereof such as vinyl chloride / vinylidene chloride, vinyl chloride / vinyl acetate or vinylidene chloride / vinyl acetate copolymers. 231527 13 9. Polymers derived from ^,^-unsaturated acids and derivatives thereof such as polyacrylates and polymethacrylates; polymethyl methacrylates, polyacrylamides and polyacrylonitriles, impact-modified with butyl acrylate. 10. Copolymers of the monomers mentioned under 9) with each other or with other unsaturated monomers, for example acrylonitrile / butadiene copolymers, acrylonitrile / alkyl acrylate copolymers, acrylonitrile / alkoxyalkyl acrylate or acrylonitrile / vinyl halide copolymers or acrylonitrile / alkyl methacrylate / butadiene terpolymers. 11. Polymers derived from unsaturated alcohols and amines or the acyl derivatives or acetals thereof, for example polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, polyvinyl butyral, polyallyl phthalate or polyallyl melamine; as well as their copolymers with olefins mentioned in 1) above. 12. Homopolymers and copolymers of cyclic ethers such as polyalkylene glycols, polyethylene oxide, polypropylene oxide or copolymers thereof with bisglycidyl ethers. 13. Polyacetals such as polyoxymethylene and those polyoxymethylenes which contain ethylene oxide as a comonomer; polyacetals modified with thermoplastic polyurethanes, acrylates or MBS. 14. Polyphenylene oxides and sulfides, and mixtures of polyphenylene oxides with styrene polymers or polyamides. 15. Polyurethanes derived from hydroxyl-terminated polyethers, polyesters or polybutadienes on the one hand and aliphatic or aromatic polyisocyanates on the other, as well as precursors thereof. 16. Polyamides and copolyamides derived from diamines and dicarboxylic acids and / or from aminocarboxylic acids or the corresponding lactams, for example polyamide 4, polyamide 6, polyamide 6 / 6, 6 / 10, 6 / 9, 6 / 12, 4 / 6, 12 / 12, polyamide 11, polyamide 12, aromatic polyamides starting from m-xylene diamine and adipic acid; polyamides prepared from hexamethylenediamine and isophthalic or / and terephthalic acid and with or without an elastomer as modifier, for example poly-2,4,4,-trimethylhexamethylene terephthalamide or poly-m-phenylene isophthalamide; and also block copolymers of the aforementioned polyamides with polyolefins, olefin copolymers, ionomers or chemically bonded or grafted elastomers; or with polyethers, e.g. with polyethylene glycol, polypropylene glycol or polytetra- methylene glycol; as well as polyamides or copolyamides modified with EPDM or ABS; and polyamides condensed during processing (RIM polyamide systems). 17. Polyureas, polyimides, polyamide-imides, polyetherimids, polyesterimids, polyhydantoins and polybenzimidazoles. 18. Polyesters derived from dicarboxylic acids and diols and / or from hydroxycarboxylic acids or the corresponding lactones, for example polyethylene terephthalate, polybutylene terephthalate, poly-1,4-dimethylolcyclohexane 231527 14 terephthalate, polyalkylene naphthalate (PAN) and polyhydroxybenzoates, as well as block copolyether esters derived from hydroxyl-terminated polyethers; and also polyesters modified with polycarbonates or MBS. 19. Polycarbonates and polyester carbonates. 20. Polyketones. 21. Polysulfones, polyether sulfones and polyether ketones. 22. Blends of the aforementioned polymers (polyblends), for example PP / EPDM, Polyamide / EPDM or ABS, PVC / EVA, PVC / ABS, PVC / MBS, PC / ABS, PBTP / ABS, PC / ASA, PC / PBT, PVC / CPE, PVC / acrylates, POM / thermoplastic PUR, PC / thermoplastic PUR, POM / acrylate, POM / MBS, PPO / HIPS, PPO / PA 6.6 and copolymers, PA / HDPE, PA / PP, PA / PPO, PBT / PC / ABS or PBT / PET / PC. The thermoplastic polymer can be virgin or a recycled polymer, which may be obtainable from domestic,commercial and industrial waste or from useful material collections. The recycled polymer may originate fromseparation and sorting, or from specific industrial sectors and return obligations, for example from the automobile industry, electrical / electronic industry, construction, agriculture and the textile industry, or from households and commerce (for example supermarkets). For example the thermoplastic polymer is polypropylene, polyethylene, any polypropylene copolymer or any polyethylene copolymer or any of their blends.Preferably the thermoplastic polymer is a linear low density polyethylene (LLDPE).The oligomeric hindered amine may be added directly to the extruder together with the thermoplastic polymer or itmay be premixed with the thermoplastic polymer and then added to the extruder.Optionally, an interfacial agent can be incorporated in the composition. The role of a interfacial agent may be thereduction of the onset time or induction time until the polymer processing aid (PPA) effect is observable, or to furtherlower the melt viscosity or energy consumption required for compounding the polymer, or for enhancedprocessability. The interfacial agent often os a relatively low molecular weight ingredient which, for a particularsystem of PPA plus thermoplastic polymer, preferentially locates at the interface between these two polymers. The interfacial agent may be introduced to the polymer at any point up to and including the final melt shaping process. It is most desirable to combine the interfacial agent in a masterbatching step where both ingredients are present at high concentration (i. e. at a concentration greater than or equal to 0.5 wt. %, based on the total weight of masterbatch). Possible interfacial agent are, among others, thermoplastic polymers which are characterized by 1) being in the liquid state (or molten) at the extrusion temperature, 2) having a lower melt viscosity than both the melt processable polymer and the comb or comb block copolymer process aid, and 3) freely wets the surface of the comb or comb block copolymer particles in the extrudable composition. Examples of such interfacial agent include, but are not limited to i) silicone-polyether copolymers ; ii) aliphatic polyesters such as poly (butylene adipate), poly (lactic acid) and polycaprolactone polyesters; iii) aromatic polyesters such as phthalic acid diisobutyl ester; iv) polyether polyols (preferably, not a polyalkylene oxide) such as poly (tetramethylene ether glycol) ; v) amine oxides such as octyldimethyl amine oxide; vi) carboxylic acids such as hydroxybutanedioic acid; vii) fatty acid esters such as sorbitan monolaurate and triglycerides; and vii) poly (oxyalkylene) polymers, including polyethylene glycols and theirderivatives. Preferred aliphatic interfacial agent are polyethylene glycol or aliphatic polyester (preferablypolycaprolactone) having a number average molecular weight in the range 500 to 32000, preferably 1000 to 15000, and most preferably 2000 to 12000.The thermoplastic polymer may comprise a further additive such as antioxidant, UV absorber, light stabilizer, metaldeactivator, peroxide scavenger, nucleating agent, filler, reinforcing agent, a partitioning agent, preferably aninorganic partitioning agent, such as calcium carbonate, silicon oxide, talc or any combination thereof.For ease of processing, the oligomeric hindered amines are often used in the form of a masterbatch, rather thanneat, when they are added to the polymer. Within the scope of this invention, a masterbatch is usually a mixture ofthe oligomeric hindered amine in a carrier polymer. The carrier polymer can be the same polymer that is to be extruded, or it can be a second polymer that does not deleteriously affect the extrusion behaviour of the thermoplastic polymer that is to be extruded. Masterbatches typically contain 0.5-50 wt. %, preferably 1-30 wt. % of the oligomeric hindered amines, based on the total weight of the masterbatch. Masterbatches can be made, for example, by mixing the appropriate amount of the oligomeric hindered amine with carrier polymer in a mixer (e.g. Banbury mixer) or a co-rotating twin screw extruder, at a temperature above the melting point of the polymer.Typically such a masterbatch contains a) the carrier polymer, b) 0.5 to 50 weight percent of the the oligomerichindered amines, and optionally c) an effective amount of a interfacial agent. Preferably, the melt is processed by extrusion, such as film extrusion (cast film; blown film), fiber extrusion, pipe extrusion, profile extrusion, sheet extrusion; or tape extrusion. 16The invention also relates to a process for improving the flow properties of a melt comprising a thermoplasticpolymer, which comprises the step of incorporating the oligomeric hindered amine into the thermoplastic polymerprior to or during melt processing (preferably extrusion),where the thermoplastic polymer is free of a polymer processing aid, preferably of a fluorine-based polymer.The melt processing is preferably an extrusion, such as film extrusion (cast film; blown film), fiber extrusion, pipeextrusion, profile extrusion, sheet extrusion; or tape extrusion.ExamplesPolyethylene A: a commercial high molecular weight linear low-density polyethylene ExxonMobil LL 1201 XVfrom ExxonMobil.Polyethylene B: a commercial high molecular weight linear low-density polyethylene ExxonMobil LD 251 from ExxonMobil.Fluoro-PPA: Dynamar® FX 5920A, a commercially available polymer processing aid from the company 3M,comprising a vinylidene fluoride-hexafluoropropylene fluoroelastomer (25-35 wt%), an interfacialagent like PEG (60-70 wt%) and small amounts of partitioning agents like talc and calcium carbonate both in concentration of <5 wt%.HALS-1: A high molecular weight hindered amine light stabilizer (molecular weight about 1700 g / mol) ofthe formula (a1).HALS-2: A commercially available high molecular weight hindered amine light stabilizer from BASF SE,molecular weight 2600-3400 g / mol, of the formula 231527 17 Example 1: Preparation of masterbatchesThe Polyethylene A or B and processing aids Fluoro-PPA, HALS-1, HALS-2, HALS-3 or HALS-4 were blended in theamounts as indicated in Table 1 and then melt compounded into pellets on a 25 mm co-rotating twin-screw extruder Berstorff ZE25A x 47D, operating at 160 revolutions per minute (rpm) and at set temperatures of 190 °C, and extruded into pellets. Table 1: Composition of masterbatches MB-Aa) MB-B MB-C MB-DPolyethylene A 95 %Polyethylene B 85 % 85 % 85 %Fluoro-PPA 5 %HALS-1 15 % 7.5%HALS-2 15% 7.5%a) ComparativeExample 2: Performance as processing aidThe pelletized masterbatch from Example 1 and Polyethylene A were dry blended in the amounts as indicated inTable 2 and melt processed into monofilament through a 1.5 mm die on a 20 mm single screw extrusion, Extrusionmeter 20D at set temperatures of 220 °C. For each masterbatch tested, the time until the melt fracture or shark-skin was eliminated from extrudedmonofilament was recorded in Table 2.Between each formulations the extruder was purged with Polyethylene A untill the original pressure observed withthe neat polymer was re-stored and only after the subsequent formulation was tested.The masterbatches MB-B, MB-C and MB-D increased significantly the processing performance of the thermoplasticpolymer.In Figure 1 a photograph of Monofilament Sample 1 (comparative) after 5 min (A) and after 60 min (B) is shown. Itshowed that even after 60 min the shark skin was not eliminated. In Figure 2 a photograph of Monofilament Sample 3 after 5 min (A) and after 30 min (B) is shown. It showed that already after 30 min the shark skin was no longer visible.In Figure 3 a photograph of Monofilament Sample 6 after 5 min (A) and after 15 min (B) is shown. It showed thatalready after 15 min the shark skin was no longer visible. 231527

Claims

231527 19 Table 2 Monofilament Sample Masterbatch Time until Shark-Skinno longer visible 1a) --- Shark skin not eliminated2 a) 1 % MB-A 30 min3 3.5 % MB-D 30 min4 6.5 % MB-D 60 min5 3.5 % MB-B 30 min6 6.5 % MB-B 15 min7 5.2 % MB-B + 1.3% MB-C 30 min8 3.15 % MB-B + 0.35 % MB-C 30 min9 5.85 % MB-B + 0.65 % MB-C 30 mina) Comparative231527 20 Claims1. A use of an oligomeric hindered amine to improve the flow properties of a melt comprising a thermoplasticpolymer.

2. The use according to claim 1 where the melt comprises 0.01 to 4 wt%, preferably 0.05 to 2 wt%, morepreferably from 0.1 to 1.5 wt% and in particular from 0.2 to 1.0 wt% of the oligomeric hindered amine.

3. The where the oligomeric hindered amine has a molecular weight of at least 1000and in particular at least 1500 g / mol.

4. The1to 3 where the thermoplastic polymer is polypropylene, polyethylene, anypolypropylene copolymer or any polyethylene copolymer or any of their blends.

5. The use according to any of claims 1 to 4 where the thermoplastic polymer is a linear low density polyethylene.6.7.8.

9. of at least10. The use according to any of claims 1 to 9 where the oligomeric hindered amine comprises a compoundselected from a compound of the formula (I) b (I) b1231527 21 the radicals R1independently of one another are hydrogen, C1-C8alkyl, O., -OH, -CH2CN, C1-C18alkoxy, C5- C12cycloalkoxy, C3-C6alkenyl, C7-C9phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C1-C4alkyl; or C1-C8acyl; R2is C2-C18alkylene, C5-C7cycloalkylene or C1-C4alkylenedi(C5-C7cycloalkylene); unsubstituted or substituted C4alkyl; C7-C9phenylalkyl of the formula (Ia)H3CC H3(Ia) or R3 and R4, together with the nitrogen atom to which they are linked, form a 5- to 10-membered heterocyclic ring;and / or a compound of the formula (II) NNZ1 NN N H3C CH3Z1Z1X1NN H3C CH3Y1NH NH N N N N Y N N 1N N Y1 Y1 N N Y1H3C CH3H3C CH3H3C CH3H3C CH3H3C NCH3 H3C NCH3 H3C NCH3 H3C NCH3X1X1X1X1b2(II) wherein b2is a number from 1 to 20; the radicals X1independently of one another are hydrogen, C1-C8alkyl, O., -OH, -CH2CN, C1-C18alkoxy, C5- C12cycloalkoxy, C3-C6alkenyl, C7-C9phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C5-C12cycloalkyl unsubstituted or 1, 2 or 3 C1-C4alkyl; C7-C9phenylalkyl of the formula (IIa);H3CC H3(IIa)

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