Polymer processing aids for polyethylene compositions

Abstract

Polyethylene composition comprising an ethylene polymer and from 100 ppm to 10,000 ppm of a polymer processing aid (PPA) that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two compounds selected from a polyphosphite, a polysiloxane, a polyethylene glycol, a high melt flow rate polypropylene, a high melt flow rate polybutene-1, a metal salt of a fatty acid, a polyamide and a boron nitride and the use of such PPA as melt fracture suppressor for polyethylene extruded articles.

Description

POLYMER PROCESSING AIDS FOR POLYETHYLENE COMPOSITIONSFIELD OF THE INVENTION

[0001] The present disclosure relates to polyethylene compositions containing polymer processing aids and the methods of using the same. More particularly, the present disclosure relates to linear low density polyethylene compositions, including blown and cast films, containing polymer processing aids that are substantially free of fluoropolymer compounds and methods of using the same.BACKGROUND OF THE INVENTION

[0002] Linear low-density polyethylene (LLDPE) is a substantially linear polymer, with significant numbers of short branches, commonly made by copolymerization of ethylene with higher alpha-olefins such as butene, hexene, or octene. LLDPE differs structurally from conventional low-density polyethylene (LDPE) because of the absence of long chain branching. LLDPE polymers are most commonly produced and sold as pellets or resin, formed in postpolymerization reactor finishing processes (such as extrusion of polymer product that is in an at least partially molten state, followed by pelletization). Additives are commonly blended into the LLDPE pellets or resin as part of this finishing process, such that the LLDPE pellets or resin comprise the LLDPE polymer itself and one or more additives. One of the more common uses of LLDPE resin is the extrusion into blown films and cast films.

[0003] Polymer processing aids (PPAs) are additives used in plastic products, like in LLDPE resin products. PPAs help make the resin easier to process in downstream manufacturing processes (such as extrusion, rolling, blowing, casting, and stretching). PPAs also help to eliminate melt fracture (as defined below) in blown and cast films made from the LLDPE resin. This is particularly important for grades of LLDPE resins exhibiting relatively high viscosity in extrusion processing. Melt fracture can adversely affect LLDPE film properties, distort clarity, and reduce gauge uniformity as well as decrease extrusion process productivity. Hence, melt fracture-prone grades of LLDPE for blown film and cast film processing often include PPAs to help eliminate melt fracture, and improve film quality and productivity.

[0004] The most common PPAs are, or include, fluoropolymers (fluorine-containing polymers). However, fluoropolymers continue to come under increased scrutiny from anenvironmental and health perspective. In particular, perfluoroalkyl and polyfluoroalkyl materials are being phased out and / or regulated out of use in many industries.

[0005] Hence, there is a need to find alternative PPAs that do not include fluoropolymers and / or fluorine for use in polyethylene compositions, in particular in LLDPE compositions, while still maintaining effectiveness at least comparable to fluoropolymer-based PPAs in preventing melt fractures during polymer manufacturing processes, like during blown film and cast film processing.SUMMARY OF THE INVENTION

[0006] In one form of the present disclosure, provided is a polyethylene composition comprising an ethylene polymer and from 100 ppm to 10,000 ppm of a polymer processing aid (PPA) that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two components selected from polyphosphites, polysiloxanes, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate poly butenes- 1 , metal salts of a fatty acid, polyamides and boron nitrides.

[0007] In a further form of the present disclosure, provided is a polyolefin masterbatch comprising a carrier resin and from 1% to 50% by weight of a polymer processing aid that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two components selected from polyphosphites, polysiloxanes, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate polybutenes- 1, metal salts of a fatty acid, polyamides and boron nitrides.

[0008] In another form of the present disclosure, provided is a process to prepare a polyethylene extruded article comprising:(i) providing a polyethylene composition comprising an ethylene polymer and from 100 ppm to 10,000 ppm of a polymer processing aid that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two components selected from polyphosphites, polysiloxanes, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate polybutenes- 1, metal salts of a fatty acid, polyamides and boron nitrides; and(ii) extruding the polyethylene composition into the polyethylene extruded article.

[0009] In yet another form of the present disclosure, provided is a method of decreasing melt fracture in a polyethylene extruded article, comprising extruding an ethylene polymer on an extrusion line; and blending into the extrusion line a polymer processing aid that is substantiallyfree of fluorine-containing compounds to provide a polyethylene extruded article comprising from 100 ppm to 10,000 ppm of the polymer processing aid, wherein the polymer processing aid is a blend of at least two components selected from polyphosphites, polysiloxanes, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate polybutenes- 1, metal salts of a fatty acid, polyamides and boron nitrides.

[0010] In yet another form of the present disclosure, provided is a polyethylene extruded article comprising an ethylene polymer and from 100 ppm to 10,000 ppm of a polymer processing aid that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two components selected from polyphosphites, polysiloxanes, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate poly butenes- 1 , metal salts of a fatty acid, polyamides and boron nitrides.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims, and accompanying drawings where:

[0012] Figure 1 is a graph showing the observed melt fracture % over time for trial LLDPE films produced using inventive PPAs of examples El and E2, and comparative PPAs of comparative examples CE3-CE5.

[0013] Figure 2 is a graph showing the observed melt fracture % over time for trial films produced using inventive PPA of examples E6-E10, and comparative PPAs of comparative examples CE11-CE13.

[0014] It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings.DETAILED DESCRIPTION OF THE INVENTION

[0015] The present disclosure relates to a polyethylene composition containing a polymer processing aid (PPA) to help decrease or eliminate melt fracture during processing. The polyethylene compositions containing the PPA provided herein are substantially free of fluoropolymer compounds. Also provided are polyolefin masterbatches including such PPA. Still also provided is a process to make polyethylene extruded articles including the PPA and a methodof decreasing melt fracture in polyethylene extruded articles produced with such PPA, as well as a polyethylene extruded article including such PPA.

[0016] The present disclosure provides for a PPA that may be incorporated into polyethylene compositions to improve their processing and productivity performance, as well as the quality of products in terms of visual appearance that may be made from such polyethylene compositions.

[0017] The details of the PPA, polyolefin masterbatches including such PPA, polyethylene compositions including such PPA, process to make extruded articles containing the polyethylene compositions including such PPA, and methods of decreasing melt fracture in polyethylene extruded articles making use of such PPA are provided below.

[0018] For the purposes of the present disclosure, various terms are defined as follows:

[0019] The term “alpha-olefin” or “a-olefin” refers to an olefin having a terminal carbon-to- carbon double bond in the structure thereof R1R2C=CH2, where R1and R2can be independently hydrogen or any hydrocarbyl group. A “linear alpha-olefin” is an alpha-olefin wherein R1is hydrogen and R2is a linear alkyl group.

[0020] The term “extrusion” or “extruding” refers to processes that include forming a polymer and / or polymer blend into a melt, such as by heating and / or shear forces, and then forcing the melt out of a die in a form or shape such as in a film, a sheet or a pipe, or in strands that are pelletized. Typical extrusion apparatus includes a single-screw extruder or twin-screw extruder, or other meltblending device as is known in the art and that can be fitted with a suitable die. It will also be appreciated that extrusion can take place as part of a polymerization process (in particular, in the finishing portion of such process) as part of forming polymer product (such as polymer pellets); or it can take place as part of the process for forming articles such as films, pipes and wire and cable sheaths or coverings from the polymer pellets. In the context of the present disclosure, extrusion in the finishing portion of polymerization processes may be referred to as compounding extrusion, and typically involves feeding additives plus additive-free (reactor grade) polymer to the extruder; while extrusion of polymer to make articles (e.g., extrusion of polymer pellets to make films) takes place downstream (e.g., at a later point, after polymer product has been formed including through compounding extrusion), and typically involves feeding optional additives plus additive-containing polymer to the extruder.

[0021] The term “finishing” refers to post-polymerization reactor processing steps where additives, such as PPAs, may be incorporated into a polymer to form a finished polymer product,such as polyethylene pellets or resin, with one example of a finishing process being the compounding extrusion just discussed. Finishing occurs prior to further processing of the finished polyethylene product (resin or granules) into articles such as films, sheets or pipes.

[0022] The term “polyolefin” or “olefin polymer” refers to polymers (including bio-based synthetic polymers and recycled polymers) formed from at least one olefin as a monomer, and includes both homopolymers and copolymers, (e.g., bipolymers, terpolymers, etc.), and blends thereof. In addition, they include polymers of ethylene (i.e., polyethylene), which include LDPE, LLDPE, MDPE, HDPE, copolymers of ethylene with one or more alpha-olefins, copolymers of ethylene with a vinyl ester comonomer, and blends thereof. They also include polymers of propylene (i.e., polypropylene), copolymers (e.g., bipolymers, terpolymers, etc.) of propylene with one or more alpha-olefins, and blends of different polyolefins. They also include polymers of butylene (i.e., polybutene), copolymers (e.g., bipolymers, terpolymers, etc.) of butylene with one or more alpha-olefins, and blends of different polyolefins.

[0023] The term “LLDPE” refers to a linear-low density polymer containing a copolymer of ethylene and one or more alpha-olefins polymerized in the presence of one or more Ziegler-Natta catalysts, one or more metallocene catalysts, and combinations thereof. Such LLDPE can have density within the range from a low of 0.900, 0.905, 0.907, 0.910 g / cm3to a high of 0.920, 0.925, 0.930, 0.935, 0.940, to a high of 0.945 g / cm3. Preferably, the LLDPE has density within the range from 0.900 to 0.940 g / cm3, more preferably from 0.905 to 0.935 g / cm3, still more preferably from 0.907 to 0.930, g / cm3, still more preferably from 0.910 to 0.920 g / cm3. In particular embodiments, the LLDPE includes a metallocene-catalyzed LLDPE (mLLDPE). In yet other embodiments, the LLDPE includes a Ziegler-Natta catalyzed LLDPE (or ZN-LLDPE). LLDPE can be produced in gas, slurry, or solution phase polymerization, and some particularly preferred LLDPEs can be produced in gas or slurry phase polymerization.

[0024] The term “LLDPE polymer composition” refers to a composition containing a LLDPE polymer. The LLDPE polymer composition can be in any form. Some examples include: the form of a reactor grade (e.g., granules or resin) containing the LLDPE polymer; the form of a molten or at least partially molten composition containing the LLDPE polymer and one or more additives undergoing or about to be undergoing the process of finishing (such as in the process of compounding extrusion); the form of a finished LLDPE polymer product such as LLDPE polymer pellets containing the LLDPE and any additives (such as PPA); or the form of a finished LLDPEproduct such as LLDPE resin undergoing the process of mixing (e.g., via coextrusion, melt blending, or other processing) with additives, such as in the case of LLDPE being extruded to form blown film, cast film or other polymer-containing article.

[0025] The term “masterbatch” refers to a powdered, granulate, or pelletized composition comprising a mixture of two or more components that is used to simplify forming a product comprising the components, rather than forming the product from the individual components. In addition, as used herein, the term encompasses both concentrated compositions, which are formulated to be mixed with one or more base resins during the formation of the polymer product, or “fully” compounded compositions, which are not formulated to be mixed with such diluents. Unless context otherwise suggests, the phrase “MB” is used herein to denote “masterbatch.”

[0026] The term “melt fracture” refers to a mechanically-induced melt flow instability which occurs, e.g., at the exit of an extrusion die and typically in conditions of high shear rate. Pinhole, linear, and annular die geometries are among those that can induce melt fracture. There are different mechanical regimes that describe polymer melt fracture, but all manifest as a very rough polymer surface which persists as the polymer crystallizes. Lor instance, in the blown film processing, a rough array of sharkskin like patterns develop on the film surface, often with a characteristic size from the mm to cm scale, and they depend on both the flow profile and rheology of the polymer.

[0027] The term “comprising” should be construed to mean “comprising or consisting essentially of’ and the term “consisting essentially of’ means that, in addition to those components which are mandatory, other components may also be present in the material, provided that the essential characteristics of the material are not materially affected by their presence. Examples of components that, when present in customary amounts, do not materially affect the characteristics of a polymer or of a polyolefin composition, are mixture or blend are catalyst residues.

[0028] The term “skin layer” is referred to an outermost layer of a multilayer film;

[0029] The term “base layer(s)” is referred to the inner layer(s) of a multilayer film, onto which at least one skin layer is preferably adhered.

[0030] In the context of the present disclosure, a “film” is thin layer of material having total thickness equal to or lower than 5000 pm. A “sheet” is a layer of material more than 5000 pm thick.

[0031] Additionally, in the context of the present disclosure the percentages are expressed by weight, unless otherwise specified.

[0032] In a first aspect, the present disclosure refers to a polyethylene composition comprising an ethylene polymer and from 100 ppm to 10,000 ppm of a polymer processing aid (PPA) that is substantially free of fluorine- containing compounds, wherein the polymer processing aid is a blend of at least two components selected from polyphosphites, polysiloxanes, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate polybutenes- 1, metal salts of a fatty acid, polyamides and boron nitrides.

[0033] Preferably, the polyethylene composition comprises from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm of the polymer processing aid.

[0034] The ethylene polymer is preferably selected from the group consisting of LDPE, LLDPE, MDPE, HDPE, elastomeric copolymers of ethylene with one or more alpha-olefins, copolymers of ethylene with a vinyl ester comonomer, and combinations thereof. In a particularly preferred embodiment, the ethylene polymer is a metallocene-catalyzed LLDPE, a Ziegler-Natta LLDPE, an LDPE, or a combination thereof.

[0035] The PPA may be incorporated or blended into the ethylene polymer as part of a finishing step after the polymerization process or alternatively may be incorporated into the ethylene polymer during the subsequent converting step to form a finished product, such as a blown film or cast film, a sheet or a pipe. Alternatively, the PPA may be incorporated into the polyethylene compositions as a polyolefin masterbatch.

[0036] Accordingly, in a further aspect, the present disclosure refers to a polyolefin masterbatch comprising a carrier resin and from 1 wt.% to 50 wt.%, preferably from 2 wt.% to 20 wt.%, more preferably from 3 wt.% to 15 wt.%, based on the weight of the polyolefin masterbatch, of a polymer processing aid that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two components selected from polyphosphites, polysiloxanes, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate polybutenes- 1, metal salts of a fatty acid, polyamides and boron nitrides.

[0037] The carrier resin for the polyolefin masterbatches is preferably an olefin polymer, more preferably selected from the group consisting of LLDPE, LDPE, MDPE, HDPE, polypropylene, like copolymers and terpolymers of ethylene, propylene and butylene, polyolefin elastomers, like propylene elastomers, and combinations thereof.

[0038] The PPA, the corresponding polyethylene compositions and polyolefin masterbatch incorporating such PPA are “substantially free” of fluorine-containing compounds, which means that the polyethylene compositions and / or the polyolefin masterbatch may include trace amounts (e.g., less than 10 ppm, preferably less than 1 ppm, such as less than 0.1 ppm) of fluorine, e.g., as an impurity, but well below the amount that would intentionally be included in a polymer composition via fluorine-containing additives (e.g., about 100 ppm of fluorine atoms by mass of polymer product in a typical case where such additives are included).

[0039] The non-fluorine containing PPA may include a combination of at least two, preferably of two, or three, or four components selected from the following classes: polyphosphites, polysiloxane, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate polybutenes- 1, metal salts of a fatty acid, polyamides and boron nitrides. In a preferred embodiment, the PPA is a blend of two components selected from different classes. The two- component PPA is preferably selected from polysiloxane and polyethylene glycol blends, polyphosphite and polysiloxane blends; high melt flow rate polybutene- 1 and polyethylene glycol blends, which are particularly advantageous.

[0040] In a preferred embodiment, in two-component PPA comprising components of different classes, the weight ratio between the two components in the blend ranges from 90: 10 to 50:50, preferably from 85:15 to 55:45, more preferably from 80:20 to 70:30. Alternatively, the weight ratio between the two components in the blend may be 20:80, or 30:70, or 40:60, or 50:50, or 60:40, or 70:30, or 80:20. In an advantageous form of this inventive PPA blend embodiment, the 50:50 weight ratio is particularly preferred.

[0041] In a further embodiment, the non-fluorine containing PPA may include a combination of two or more different components for each of the groups described above, e.g. a blend of polyamide 6 and polyamide 12, or a blend of polyethylene glycols having different molecular weights.

[0042] The non-fluorine containing PPA of the present disclosure includes a blend of at least two components selected from compounds of the following classes of materials, which are described in detail below:Polyphosphites

[0043] Homopolymeric, copolymeric and cycloaliphatic polyphosphites have been discovered as a class of compounds that function effectively as PPAs in polyethylene compositions.

[0044] In one form, the polyphosphite is a homopolymeric polyphosphite containing from 15 to 1000 repeating units of the formula:

[0045] in which R2is selected from the group consisting of C1-20 alkyl, C3-22 alkenyl, and C2- 20 polyalkylene glycol chain terminated by a Ci-4 alkyl group. The polyphosphite is terminated adjacent the — P(OR2) — group of the formula above by a group R'O — , and terminated at the other end of the chain by a group — P(OR3)(OR4), in which each of R1, R3, and R4, which may be the same or different, has one of the meanings given for R2. The homopolymeric polyphosphite may have a weight average molecular weight from 6,000 to 100,000. The C2-20 polyalkylene glycol chain may be terminated by a Ci-4 alkyl group selected from the group consisting of a polyethylene glycol terminated by a methyl group and a tripropylene glycol terminated by a butyl group. Alternatively, the R2may be a C10-20 alkyl group.

[0046] In another form, the polyphosphite may be a copolymeric polyphosphite containing from 2 to 1000 repeating units of the formula:

[0047] in which R2is selected from the group consisting of C1-20 alkyl, C3-22 alkenyl, Ce-40 cycloalkyl, Ce aryl, Ce-40 aryl alkyl and Y — OH; and from 1 to 1000 repeating units of the formula:

[0048] in which: Y is selected from the group consisting of C2-40 alkylene, C2-40 alkyl lactone, C3-40 cycloalkylene, Ce arylene and Ce-40 aryl alkylene; m ranges from 5 to 20; said copolymeric polyphosphite being terminated adjacent the — P(OR2) — group of the formula above by a group R10 — , and terminated at the other end of the chain by a group -P(OR3)(OR4), in whicheach of R1, R3, and R4, which may be the same or different and has one of the meanings given for R2. Alternatively, the R2may be a Ce-Cio cycloalkyl or the R2may be a C10-20 alkyl group.

[0049] In another form, the polyphosphite may be a polymeric polyphosphite containing from 2 to 1000 repeating units of the formula:

[0050] in which: R2is derived from a monohydroxy alcohol R2— OH end-capping group and is selected from the group consisting of a C1-20 alkyl group, a C3-22 alkenyl group, a C6-40 cycloalkyl, a Ce aryl, a C6-40 aryl alkyl and Y — OH; R7and R9are methylene groups; R8is a cyclohexylene group; a and b are 1; and from 1 to 1000 repeating units of the formula:

[0051] in which: Y is selected from the group consisting of a C2-40 alkylene group, a C2-40 alkyl lactone, a C3-40 cycloalkylene group, a Ce arylene group and a Ce-40 aryl alkylene; m ranges from 5 to 20; said polyphosphite being terminated adjacent the — P(OR2) — group of the formula above by a group R'O — , and terminated at the other end of the chain by a group — P(OR’)(OR4), in which each of R1, R3, and R4, which may be the same or different, has one of the meanings given for R2. Alternatively, the R2may be a C10-20 alkyl group.

[0052] In another form, the polyphosphite may be a copolymeric polyphosphite which comprises two different repeat units — O — Y — :

[0053] wherein each R1, R2, R3and R4can be the same or different and independently selected from the group consisting of C1-20 alkyl and C3-22 alkenyl; each Y is independently selected from two of the group consisting of C2-40 alkylene and C2-40 alkyl lactone esters; m is an integral value ranging from 2 to 100 inclusive; and x is an integral value ranging from 12 to 30. Alternatively,the above copolymeric phosphite includes polyalkylene glycol segments between the phosphite moieties, wherein the polyalkylene glycol segments are selected from the group consisting of polyethylene glycol segments and polypropylene glycol segments.

[0054] Commercially available examples of suitable polyphosphite include Songwon Songnox PQ, Dover LGP-11, and Dover LPG-12, as well as masterbatches of Dover LGP-11 (PP carrier), and Dover LPG-12 (LLDPE carrier or PP carrier).Silicones (Polysiloxanes)

[0055] Silicones have also been discovered as a class of compounds that function effectively as PPA in polyethylene compositions. In particular, high molecular weight silicones, also referred to as polysiloxanes, are advantageous as PPAs. All polymerized siloxanes, or polysiloxanes, consist of an inorganic silicon-oxygen backbone chain ( — Si-O-Si-O-Si-O — ) with two side chains attached to each silicon center. In one form, all side chains may be a methyl group and the silicone may be a polydimethylsiloxane (PDMS) having the general formula: CH3[Si(CH3)2O]nSi(CH3)3, where n is the number of repeating monomer [Si(CH3)2O] units. By varying the -Si-O- chain lengths, side groups, and crosslinking, silicones can be synthesized with a wide variety of properties and compositions. Particularly advantageous as PPAs for polyethylene compositions are silicone materials based on silicone resins, which are formed by branched and cage-like oligosiloxanes.

[0056] In a preferred embodiment, the silicone may be a polyester modified silicone having the formula:

[0057] wherein: R1are independently selected from the group consisting of: an alkyl having 1-5 carbon atoms, a substituted alkyl having 1-5 carbon atoms optionally substituted by a phenyl, and R2is selected from the group consisting of: hydrogen, alkyl of 1 to 45 carbon atoms, substituted alkyl of 1 to 45 carbon atoms optionally substituted by one or more aryl, a partially esterified ester-containing group represented by the formula:

[0058] and a reverse ester thereof represented by the formula:

[0059] and the formula:

[0060] and a reverse ester thereof represented by the formula:

[0061] provided that if R1is anything but methyl or ethyl, then R2must be a methyl, ethyl or butyl. R3is derived from a partially esterified ester residue; R8is selected from the group consisting of hydrogen, alkyl of 1 to 45 carbon atoms, substituted alkyl of 1 to 45 carbon atoms optionally substituted by an aryl and a compound derived from a partially esterified ester residue; R9is selected from the group consisting of: an arylene, an alkylene of 1 to 22 carbon atoms, substituted alkylene of 1 to 22 carbon atoms optionally substituted by an arylene; R4is selected from the group consisting of: alkyl of 1 to 45 carbon atoms, substituted alkyl of 1 to 45 carbon atoms optionally substituted by an aryl, the ester-containing group and the compound derived from reverse esters thereof, m is an integer between 1 to 22, preferably from 5 to 20; and x is an integer between 0 to 1000; wherein the composition has at least 1 compound derived from the partially esterified ester-containing group or the reverse ester thereof.

[0062] In another form, the silicone may be a polyether modified polysiloxane, wherein the side chains of a polysiloxane are partially etherified with groups -O-CH2-CHRI-O-Rn, wherein R1and Rnare independently selected from hydrogen and an alkyl having 1-10 carbon atoms.

[0063] In one embodiment, the polysiloxane is not polydimethylsiloxane or a polysiloxane of formula

[0064] wherein R is an alkyl group containing 1 to 8 carbon atoms, R1 and R2 are the same or different and are either alkyl or poly(oxyalkylene) chains, terminated with a polar or charged functional group selected from an alcohol, a primary or secondary amine, or a combination of primary and secondary amines, an ammonium ion, or a phosphate; where m is from 1 to 15,000, n is from 1 to 15,000, and p is from 0 to 5000.

[0065] Commercially available examples of suitable silicone based PPAs include: Tegomer H-Si 6441 P (multifunctional polyester modified siloxane in thermoplastic resins), Tegopren 6877 (organo-modified siloxane), Silimer 5140 (polyester modified polysiloxane), Polymer Dynamix Everglide PA45 (functional siloxane in PE carrier resin), Dow Corning MB-001 Masterbatch (50% ultra-high molecular weight siloxane in homopolymer PP carrier resin), Dow Corning MB-002 Masterbatch (50% ultra-high molecular weight siloxane in LDPE carrier resin), Dupont Multibase MB25-035 Masterbatch (siloxane polymer in LDPE carrier resin), and Dupont Multibase MB25- 235 Masterbatch (siloxane polymer in LDPE carrier resin).Polyethylene Glycols

[0066] Polyethylene glycols (PEGs) have been discovered as a class of compounds that function effectively as PPAs in polyethylene compositions. As used herein, polyethylene glycol or PEG refers to a polymer expressed as H — (O — CH2 — CH2)n — OH, where n represents the number of times the O — CH2 — CH2 (oxyethylene) moiety is repeated; n can range widely, because PEG comes in a wide variety of molecular weights. For instance, n can be about 33 for lower-molecular weight polyethylene glycols ('1500 g / mol), ranging up to about 227 for higher molecular weight polyethylene glycols ('10,000 g / mol); and, about 454 for '20,000 g / mol molecular- weight PEG; and about 908 for '40,000 molecular-weight PEG; and even higher for higher molecular-weightPEG varieties. It is also noted that PEG can equivalently be referred to as polyethylene oxide (PEO) or polyoxyethylene (POE). Sometimes in industry parlance, PEG is the nomenclature used for relatively lower molecular weight varieties (e.g., molecular weight 20,000 g / mol or less), while polyethylene oxide or PEO is used for higher-molecular-weight varieties (e.g., above 20,000 g / mol). However, for purposes of the present disclosure, references to polyethylene glycol or PEG should not, alone, be taken to imply a particular molecular weight range, except where a molecular weight range is explicitly stated. That is, the present application may use the terms polyethylene glycol or PEG to refer to a polymer having structure H — (O — CH2 — CH2)n — OH with n such that the polymer's molecular weight is less than 20,000 g / mol, and it may also use the terms polyethylene glycol or PEG to refer to such a polymer with n such that the polymer's molecular weight is greater than 20,000 g / mol, such as within the range from 20,000 to 40,000 g / mol.

[0067] PEG “molecular weight” as used herein refers to weight-average molecular weight (Mw) as determined by gel permeation chromatography (GPC), and PEG “molecular weight distribution” or MWD refers to the ratio of Mw to number-average molecular weight (Mn), i.e., Mw / Mn. PEG for use in PPAs may advantageously have narrow MWD, such as within the range from a low of any one of about 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5 to a high of any one of about 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, or 3.0, with ranges from any foregoing low end to any foregoing high end contemplated, provided the high end is greater than the low end. Preferably, PEG has MWD ranging from 1.0 to 3.0, more preferably from 1.0 to 2.0, still more preferably from 1.0 to 1.5. For instance, PEG compositions having MWD of about 1.0 to 1.1 or 1.2 may be particularly useful. However, obtaining such a uniform length of polymer chains (i.e., narrow MWD) can be expensive; thus, commercially available PEG might have broader MWD values (e.g., ranging from 1.0 to 3.0, 4.0, 5.0, or even greater). Such PEG compositions are therefore also within the scope of the present disclosure. These PEG compositions can still suitably be employed as PPAs, potentially (but not necessarily) compensating by increasing the PEG loading for such broader-MWD PEGs (e.g., 700-1400 ppm, as compared to loadings as low as 400-700 ppm for narrower-MWD PEGs).

[0068] In embodiments employing narrow MWD PEG, Mw values for PEG will commonly be in relatively close agreement with Mn (e.g., within 10%); regardless, however, where differences between the two (Mw and Mn) exist, Mw should control as the preferred “molecular weight” measurement for purposes of the present disclosure. It is also noted that many commercialPEG compounds include a nominal molecular weight (e.g., “PEG 3K” or “PEG 10K” indicating nominal 3,000 g / mol and 10,000 g / mol molecular weights, respectively). Again, Mw of the PEG should control over any contrary nominal indicator.

[0069] Polyethylene glycols suitable for use as PPAs can include PEG of a variety of molecular weights, preferably including PEG having Mw ranging from as low as 500 g / mol to as high as 200,000 g / mol, such as from a low of any one of 500, 600, 700, 800, 900, 1000, 3000, 5000, 7000, or 7500 g / mol to a high of 40000, 50000, 60000, 75000, 80000, 90000, 100000, 125000, 150000, 175000, or 200000 g / mol, with ranges from any low end to any high end contemplated.

[0070] In certain embodiments, however, particularly preferred PEGs are those having molecular weight less than 40000 g / mol; such as within the range from a low of any one of 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 7000, 8000, 8500, 9000, 9500, 10000, 12500, and 15000 g / mol to a high of any one of 7000, 7500, 8000, 8500, 9000, 9500, 10000, 10500, 11000, 11500, 12000, 12500, 15000, 20000, 22000, 25000, 30000, 35000, 39000, and 39500 g / mol, provided the high end is greater than the low end, and with ranges from any foregoing low end to any foregoing high end generally contemplated. Particularly higher or lower sub-ranges may also be suitable (e.g., PEG having Mw of 1,500 to 5,500 g / mol; or PEG having Mw of 5,000 to 12,000 g / mol; or PEG having Mw of 10,000 to 20,000 g / mol; or PEG having Mw of 15,000 to 25,000 g / mol; or PEG having Mw of 25,000 to 35,000 g / mol).

[0071] In a preferred embodiment, PEGs have molecular weight of less than 40,000 g / mol, preferably ranging from 1,500 to 35,000 g / mol, more preferably from 5,000 to 20,000 g / mol, still more preferably from 5,000 to 12,000 g / mol, particularly preferably from 6,000 to 12,000 g / mol.

[0072] However, as noted, it is contemplated that PEG-based PPA compositions of many embodiments as described herein do not include polyethylene glycol (or polyethylene oxide) having molecular weight greater than 40,000 g / mol. That is, it is preferred that all or substantially all polyethylene glycol of the polymer compositions has molecular weight less than 40,000 g / mol; such as less than 35,000 g / mol, or less than 33,000 g / mol, or less than 22,500 g / mol, or less than 20,000 g / mol, or less than 12,000 g / mol, such as less than 10,000 g / mol. In this context, “substantially all” means that minor amounts (50 ppm or less, more preferably 10 ppm or less, such as 1 ppm or less) of higher-molecular weight PEG could be included while not losing theeffect of including predominantly the lower-molecular-weight PEGs described herein. Put equivalently, the PEG having molecular weight greater than 40,000 g / mol is absent or substantially absent from the polymer compositions. It is believed that the focus on lower molecular-weight PEG enables generally lower loadings of the PEG-based PPA to achieve the desired elimination of melt fractures across most grades of ethylene polymers that might experience melt fracture when formed into extruded articles. Similarly, lower molecular-weight PEG is believed to diffuse faster to the surface of polymer material being extruded in, e.g., blown film processes, as compared to higher molecular weight varieties of PEG; therefore, the lower molecular- weight PEG varieties will typically lead to faster elimination of melt fracture in extruded articles (and therefore lower off-spec production). However, it is nonetheless contemplated that higher-molecular weight PEG (e.g., Mw>40,000 g / mol) may be appropriate in some cases for certain ethylene polymers, despite the above-noted advantages of lower-molecular weight PEG; hence the contemplation that such higher-molecular weight PEGs may be included in polyethylene compositions that are still within the spirit and scope of some embodiments of the present invention.

[0073] Commercially available examples of suitable polyethylene glycols, especially those of lower molecular weight, include: Pluriol® E 1500; Pluriol® E 3400; Pluriol® E 4000; Pluriol® E 6000; Pluriol® E 8000; and Pluriol® E 9000 polyethylene glycols available from BASF (where the numbers represent nominal molecular weights of the PEG); also include Carbowax™ PEG 8000, and Carbowax™ PEG 400 available from Dow; and also includes Polyglykol 8000S PEG from Clariant.High Melt Flow Rate Polypropylenes

[0074] High melt flow rate polypropylene has also been discovered as a class of compounds that function effectively as PPAs in polyethylene compositions. The high melt flow rate polypropylene may include propylene copolymers with ethylene and / or butylene.

[0075] Suitable polypropylene includes propylene homopolymers and random copolymers with ethylene or other alpha- olefins. Propylene homopolymers are preferred. Propylene homopolymers can be isotactic, syndiotactic, or atactic, or mixtures thereof. In at least one embodiment, isotactic polypropylene is preferred because of its crystalline nature. Suitable random polypropylene copolymers include propylene-ethylene copolymers and propylene-C4 to CIO alpha-olefin copolymers. Examples of C4 to CIO alpha-olefins include 1 -butene, 1 -hexeneand 1 -octene. Propylene-ethylene copolymers contain 1 to 20 wt. % recurring units of ethylene, preferably 1 to 10 wt. %, based on the weight of the copolymer.

[0076] “High melt flow rate” for the purposes of polypropylene of this disclosure corresponds to a melt flow rate as measured by ASTM DI 238 or ISO 1133-1 at 230°C with a load of 2.16 kg of at least 200 g / 10 min, or at least 400 g / 10 min, or at least 600 g / 10 min, or at least 800 g / 10 min, or at least 1000 g / 10 min, or at least 1200 g / 10 min, or at least 1400 g / 10 min, or at least 1600 g / 10 min, or at least 1800 g / 10 min. “High melt flow rate” for the purposes of polypropylene of this disclosure also corresponds to a melt flow rate as measured by ASTM D1238 or ISO 1133-1 of less than 4000 g / 10 min, or less than 3500 g / 10 min, or less than 3000 g / 10 min, or less than 2500 g / 10 min, or less than 2000 g / 10 min. Generally, ISO 1133-1 is the preferred test method of measuring MFR of extremely high melt flow rate polypropylenes.

[0077] In one preferred embodiment, the melt flow rate of the high MFR polypropylene ranges from 200 to3,000 g / lOmin, more preferably from 400 to 2,500 g / lOmin, still more preferably from 1,000 to 2,000 g / lOmin, measured by ISO 1133-1 (230°C / 2.16 kg).

[0078] Commercially available examples of suitable high MFR PP based PPAs include LyondellBasell Metocene MF650W (propylene homopolymer with MFR of 500 g / lOmin) and LyondellBasell Metocene MF650X (propylene homopolymer with MFR of 1,200 g / lOmin).High Melt Flow Rate Polybutenes-1

[0079] High melt flow rate polybutene- 1 (PB-1) has also been discovered as a class of compounds that function effectively as PPAs in polyethylene compositions. PB-1 may be used as homopolymer or as a random copolymer including one or more other alpha-olefins at a comonomer content of from 1 to 20 wt. %, based on the weight of the copolymer, although homopolymer polybutene- 1 is advantageous for this disclosure. In particular, semi-crystalline homopolymer of poly butene- 1 of high melt flow rate are effective as PPAs in polyethylene compositions.

[0080] “High melt flow rate” for the purposes of PB-1 of this disclosure corresponds to a melt flow rate as measured by ISO 1133-1 at a temperature of 190°C with a load of 2.16 kg of at least 100 g / 10 min, or at least 200 g / 10 min, or at least 300 g / 10 min, or at least 400 g / 10 min, or at least 600 g / 10 min, or at least 800 g / 10 min, or at least 1000 g / 10 min, or at least 1200 g / 10 min, or at least 1400 g / 10 min. “High melt flow rate” for the purposes of PB-1 of this disclosure also corresponds to a melt flow rate as measured by ASTM D1238 or ISO 1133-1 at a temperature of190°C with a load of 2.16 kg of less than 4,000 g / 10 min, or less than 3,500 g / 10 min, or less than 3,000 g / 10 min, or less than 2,500 g / 10 min, or less than 2,000 g / 10 min, or less than 1,500 g / 10 min. Generally, ISO 1133-1 is the preferred test method of measuring MFR of extremely high melt flow rate polybutenes.

[0081] In a preferred embodiment, the high melt flow rate polybutene- 1 has a MFR ranging from 100 to 2,000 g / 10 min, more preferably from 200 to 1,500 g / 10 min, measured by ISO 1133- 1 (190°C / 2.16 kg).

[0082] Commercially available examples of suitable high MFR PB-1 include LyondellBasell Koattro PB M 0600M (homopolymer having MFR of 600 g / lOmin) and LyondellBasell Koattro PB 0801M (homopolymer having MFR of 200 g / lOmin).Metal Salts of Fatty Acids

[0083] Metal salts of fatty acids have been discovered as a class of compounds that function effectively as PPAs in polyethylene compositions. Fatty acids, as used herein, refer to monocarboxylic acid of formula R* — COOH, where wherein R* a saturated or unsaturated aliphatic group containing at least 4 carbon atoms, preferably from 4 to 30 carbon atoms. Preferably, R* is a linear aliphatic group having at least 4 carbons, such as at least 6 or at least 8 carbon atoms, preferably from 6 to 28, more preferably from 8 to 26. R* can be saturated or unsaturated and, where unsaturated, can have one or more unsaturations. Examples include the following, where R*'s value is denoted as saturated carbon chains unless otherwise specifically noted to have one or more unsaturations: caprylic acid (where R* is C7), capric acid (R* is C9), lauric acid (R* is C11), myristic acid (R* is C13), palmitic acid (R* is C15), oleic acid (R* is C17, with a monounsaturation), stearic acid (R* is C17), arachidic acid (R* is C19), arachidonic acid (R* is C19 with multiple unsaturations), erucic acid (R* is C21, with a monounsaturation), behenic acid (R* is C21), lignoceric acid (R* is C23), and cerotic acid (R* is C23).

[0084] A variety of suitable metals for forming a salt with the fatty acid may be utilized, including, but not limited to, those of Groups 1 or 2 of the Periodic Table of the Elements (e.g., lithium, sodium, potassium, beryllium, magnesium, calcium). Also contemplated are metals with different valence such as aluminum and zinc. Non-limiting exemplary metal salts include metal stearates, such as zinc stearate, calcium stearate, and combinations thereof (although also contemplated are stearates of any other metal noted above). Zinc stearate and calcium stearate may be advantageous as PPAs in polyethylene compositions.

[0085] Commercially available examples of suitable metal salts of fatty acids include: zinc stearate (CAS: 557-05-1), which may be purchased from Silver Fern Chemical Inc., and calcium stearate (CAS: 1592-23-0), which may also be purchased from Silver Fern Chemical Inc.Polyamides

[0086] Polyamides have also been discovered as a class of compounds that function effectively as PPAs in polyethylene compositions. In particular, aliphatic polyamides such as polyamide 6 (also called nylon 6) and polyamide 12 (also called nylon 12), are advantageous as PPAs.Boron Nitrides

[0087] Boron Nitrides have also been discovered as a class of compounds that function effectively as PPAs in polyethylene compositions. Boron nitride is a thermally and chemically resistant refractory compound of boron and nitrogen, which exists in various crystalline forms that are isoelectronic to a similarly structured carbon lattice. The hexagonal graphite-like form (h-BN) is particularly advantageous as PPA, because of its good lubricant properties. Alternative forms are the cubic form (zincblende, aka sphalerite structure), which is analogous to diamond and is called c-BN, although it is softer than diamond, but its thermal and chemical stability is superior. The rare wurtzite boron nitride modification is similar to lonsdaleite, but slightly softer than the cubic form.

[0088] For the purposes of this disclosure as a PPA, the hexagonal form of boron nitride (h- BN) is particularly advantageous. h-BN is the most stable crystalline form, the most soft among boron nitride polymorphs. It is also called a-BN, g-BN, and graphitic boron nitride. Hexagonal boron nitride (point group = Deh; space group = P6? / mmc) has a layered structure similar to graphite. Within each layer, boron and nitrogen atoms are bound by strong covalent bonds, whereas the layers are held together by weak van der Waals forces. The interlayer "registry" of these sheets differs, however, from the pattern seen for graphite, because the atoms are eclipsed, with boron atoms lying over and above nitrogen atoms. This registry reflects the local polarity of the B-N bonds, as well as interlayer N-donor / B-acceptor characteristics. Likewise, many metastable forms consisting of differently stacked polytypes exist. Therefore, h-BN and graphite are very close neighbors, and the material can accommodate carbon as a substituent element to form BNCs. BCeN hybrids have been synthesized, where carbon substitutes for some B and N atoms.

[0089] Boron nitride may be incorporated into polyethylene compositions as a powder. The particle size of the powder may range from 1 to 3 microns, or 4 to 6 microns, or 5 to 9 microns, or 15 to 20 microns, or 30 to 100 microns, or 100 to 150 microns. The purity of the boron nitride is preferably greater than 99% with less than 1% oxygen, and more advantageously less than 0.5% oxygen. The bulk density of the boron nitride powder may be 0.2 to 0.6, or 0.3 to 0.5.

[0090] Commercially available examples of suitable boron nitrides include AdValue Technology Grades BN-AA, BN- A, BN- AS, BN-B, BN-SA, and BN-SC.

[0091] In a preferred embodiment, the polyethylene composition or the masterbatch composition comprise a PPA which is a blend of a polysiloxane and a polyethylene glycol, wherein the polysiloxane is a polyester modified silicone, a polyether-modified silicone or a combination thereof, and the polyethylene glycol has molecular weight of less than 40,000 g / mol, preferably ranging from 1,500 to 35,000 g / mol, more preferably from 5,000 to 20,000 g / mol, still more preferably from 5,000 to 12,000 g / mol, particularly preferably from 6,000 to 12,000 g / mol.

[0092] In a further preferred embodiment, the polyethylene composition or the masterbatch composition comprise a PPA which is a blend of high melt flow rate polybutene- 1 and polyethylene glycol, wherein the high melt flow rate polybutene- 1 has melt flow rate ranging from 100 to 2,000 g / 10 min, more preferably from 200 to 1,500 g / 10 min, measured by ISO 1133-1 (190°C / 2.16 kg) and the polyethylene glycol has molecular weight of less than 40,000 g / mol, preferably ranging from 1,500 to 35,000 g / mol, more preferably from 5,000 to 20,000 g / mol, still more preferably from 5,000 to 12,000 g / mol, particularly preferably from 6,000 to 12,000 g / mol. Other Additives

[0093] Other additives are optionally present in the polyethylene compositions or in the masterbatch composition including the inventive PPA disclosed herein. These other additives include antioxidants, stabilizers such as UV stabilizers, UV absorbers, catalyst neutralizers, as well as, slip agents, antiblock agents, heat seal enhancing additives, and other additives known in the art of polymerization, compounding and extrusion.

[0094] Additive packages including a combination of one or more additives in a carrier resin may also be used. For example, an additive package including antiblock and / or slip agents, potentially along with other additives. Non-limiting exemplary antiblock agents for the polyethylene compositions disclosed herein include talc, kaolin, feldspar, crystalline and amorphous silica, nepheline syenite, diatomaceous earth, clay, or combinations thereof. Non-limiting exemplary slip agents for the polyethylene compositions disclosed herein include amides such as erucamide and other primary fatty acid amides like oleamide; and further include certain types of secondary (bis) fatty acid amides.

[0095] Antiblock agent loadings in the polyethylene compositions disclosed herein may be from 500 to 6000 ppm, or 1000 to 5000 ppm. Slip agent loadings in the polyethylene compositions disclosed herein may be 200 to 1000 ppm, or 400 to 2000 ppm, or 600 to 3000 ppm. Antioxidants (e.g., hindered phenolics such as IRGANOX™ and IRGAFOS™ additives available from Ciba- Geigy) loadings in the polyethylene compositions disclosed herein may be from 10 to 500 ppm.

[0096] Other additives may also be included in the polyethylene compositions disclosed herein, for example the following: fillers, like talc; tackifiers, such as terpene resins, aliphatic and aromatic hydrocarbon resins, alkali metal and glycerol stearates, and hydrogenated rosins; UV stabilizers; heat stabilizers; release agents; anti-static agents; foaming agents; anti-fog agents; nucleating agents; pigments; colorants; dyes; waxes; silica; compatibilizers; ethylene-methyl acrylate copolymers and combinations thereof. These further additives are loaded in the polyethylene compositions disclosed herein in customary amounts, depending on the end use to which the polyethylene composition is destinated. Where such other additives are utilized in the polyethylene compositions disclosed herein, they are also preferably free or substantially free of fluorine.

[0097] In a preferred embodiment, the polyethylene composition of the present disclosure comprises:

[0098] - from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm of a PPA comprising or consisting of a polyester modified silicone and a polyethylene glycol, wherein the polyethylene glycol has molecular weight of less than 40,000 g / mol, preferably ranging from 1,500 to 35,000 g / mol, more preferably from 5,000 to 20,000 g / mol, still more preferably from 5,000 to 12,000 g / mol, particularly preferably from 6,000 to 12,000 g / mol, wherein the weight ratio between the polyester modified silicon and the polyethylene glycol ranges from 85: 15 to 55:45, preferably from 80:20 to 70:30;

[0099] - optionally but preferably up to and including 20,000 ppm, more preferably from 200 to 10,000 ppm, still preferably from 300 to 5,000 ppm, of a compatibilizer, preferably selected from copolymers of ethylene with polar comonomers, like acrylates, particularly methyl acrylate;the ethylene copolymer containing up to and including 50% by weight of polar comonomer, like from 10% to 30% by weight, based on the weight of the ethylene copolymer;

[0100] - from 10 to 500 ppm of at least one antioxidant; and

[0101] - up to 100 wt.% of an ethylene polymer, preferably an LLDPE.

[0102] This polyethylene composition is preferably obtained by adding to an ethylene polymer, preferably to a LLDPE, a masterbatch composition comprising:

[0103] - from 1 wt.% to 50 wt.%, preferably from 2 wt.% to 20 wt.%, more preferably from 3 wt.% to 15 wt.% of a PPA comprising or consisting of a polyester modified silicone and the polyethylene glycol has molecular weight of less than 40,000 g / mol, preferably ranging from 1,500 to 35,000 g / mol, more preferably from 5,000 to 20,000 g / mol, still more preferably from 5,000 to 12,000 g / mol, particularly preferably from 6,000 to 12,000 g / mol, wherein the weight ratio between the polyester modified silicon and the polyethylene glycol ranges from 85: 15 to 55:45, preferably from 80:20 to 70:30;

[0104] - optionally but preferably up to and including 20% by weight, more preferably from0.5% to 10% by weight, still more preferably from 1.0% to 5.0% by weight of a compatibilizer, preferably selected from copolymers of ethylene with polar comonomers, like acrylates, particularly methyl acrylate; the ethylene copolymer containing up to and including 50% by weight of polar comonomer, like from 10% to 30% by weight, based on the weight of the ethylene copolymer;

[0105] - from 0.05 wt.% to 3.0 wt.% of at least one antioxidant; and

[0106] - up to 100 wt.% of an ethylene polymer as carrier resin.

[0107] In a further preferred embodiment, the polyethylene composition comprises from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm of a PPA comprising or consisting of a polyphosphite and a polysiloxane, wherein the polyphosphite and the polysiloxane are as described above. More preferably the weight ratio of the polyphosphite to the polysiloxane in the blend is from 80:20 to 20:80, more preferably is 50:50.

[0108] Methods of introducing or blending the polymer processing aid into polyethylene compositions or the polyolefin masterbatch of the instant disclosure include adding the polymer processing aid neat to an ethylene polymer (e.g., polymer granules and / or slurry) in a postpolymerization reactor finishing process, thereby obtaining the inventive polyethylene composition or the inventive polyolefin masterbatch including the ethylene polymer and thepolymer processing aid (both per above respective descriptions), as well as any optional other additives (which may be provided to the mixture along with, before, or after the PPA). The polyethylene composition or the polyolefin masterbatch may be extruded and cut to obtain a pelletized polyethylene composition or a pelletized polyolefin masterbatch.

[0109] Alternatively, to obtain the polyethylene composition of the instant disclosure, the polymer processing aid may be blended to the ethylene polymer into the post-polymerization reactor finishing process as a masterbatch composition as described above.

[0110] It has been surprisingly and unexpectedly discovered that certain blends of non-fluorine containing compounds decrease melt fracture % in polyethylene extruded articles, like blown LLDPE films and cast LLDPE films, during extrusion processing. More particularly, PPA which are a blend of at least two compounds selected from polyphosphites, polysiloxanes, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate polybutene- 1 , metal salts of a fatty acid, polyamides and a boron nitrides have been surprisingly discovered to be highly effective as polymer processing aid relative to traditional fluoropolymer-based polymer processing aids. In particular, the inventive PPA disclosed herein when incorporated into LLDPE blown film and LLDPE cast film during extrusion processing results in a blown film or cast film such that at 90 minutes of forming the blown film or cast film, % melt fracture (on basis of area of the film’s surface) is less than equal to 90%, or less than or equal to 80%, or less than or equal to 70%, or less than or equal to 60%, or less than or equal to 50%, or less than or equal to 40%, or less than or equal to 35%, or less than or equal to 30%, or less than or equal to 25%, or less than or equal to 20%, or less than or equal to 15%, or less than or equal to 10%, or less than or equal to 5%, or less than or equal to 1%, or 0% (no melt fracture whatsoever). Alternatively, the inventive PPA disclosed herein decrease melt fracture % when incorporated into polyethylene that is extruded as a pipe, or wire and cable sheath or covering.

[0111] Accordingly, in a further aspect, the present disclosure refers to a process to prepare a polyethylene extruded article comprising:(i) providing a polyethylene composition comprising an ethylene polymer and from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm, of a polymer processing aid (PPA) that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two components selected from apolyphosphite, a polysiloxane, a polyethylene glycol, a high melt flow rate polypropylene, a high melt flow rate polybutene- 1, a metal salt of a fatty acid, a polyamide and a boron nitride; and (ii) extruding the polyethylene composition into a polyethylene extruded article.

[0112] In step (i) a ready-to-use inventive polyethylene composition may be provided. Alternatively, the polyethylene composition may be provided by blending into the extrusion line an ethylene polymer and a polymer processing aid that is substantially free of fluorine-containing compounds to provide from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm, of the polymer processing aid in the polyethylene composition, wherein the polymer processing aid is a blend of at least two compounds selected from a polyphosphite, a polysiloxane, a polyethylene glycol, a high melt flow rate polypropylene, a high melt flow rate polybutene-1, a metal salt of a fatty acid, a polyamide, or a boron nitride. In this embodiment, the polyethylene composition is an intermediate product, like a polymer melt. The polymer processing aid may be directly blended into the extrusion line, or blended into the extrusion line as the polyolefin masterbatch of the present disclosure.

[0113] The polyethylene extruded article may be a blown film, a cast film, a pipe or a wire and cable sheath or covering. Preferably, the polyethylene extruded article is a LLDPE blown film or cast film.

[0114] The inventive PPAs described above are particularly advantageous in eliminating melt fracture in polyethylene extruded articles, particularly cast or blown LLDPE films. In particular, it was observed that, when the inventive PPA disclosed herein are used to produce LLDPE blown films, the films will exhibit similar or superior properties compared to LLDPE films comprising conventional fluoropolymer based PPAs. This also exemplifies embodiments of the present disclosure including inventive PPA masterbatches, which could make for flexible LLDPE products ready for addition to any number of finished LLDPE products as needed for article production, such as blown film or cast film.

[0115] In a further aspect, the present disclosure refers also to a method of decreasing melt fracture in a polyethylene extruded article, comprising extruding an ethylene polymer into a polyethylene extruded article on an extrusion line; and blending into the extrusion line a polymer processing aid that is substantially free of fluorine-containing compounds to provide a polyethylene extruded article comprising from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm, of the polymer processing aid, whereinthe polymer processing aid is substantially free of fluorine- containing compounds and is a blend of at least two components selected from a polyphosphite, a polysiloxane, a polyethylene glycol, a high melt flow rate polypropylene, a high melt flow rate polybutene- 1, a metal salt of a fatty acid, a polyamide and a boron nitride. The polymer processing aid may be directly blended into the extrusion line or blended into the extrusion line as the polyolefin masterbatch of the present disclosure.

[0116] In a preferred embodiment, the polyethylene extruded article is a blown film, a cast film, a pipe or a wire and cable sheath or covering, more preferably the polyethylene extruded article is a LLDPE blown or cast film.

[0117] In a particularly preferred embodiment, the polyethylene extruded article is a LLDPE blown film or cast film, and the LLDPE blown film or cast film is such that at 90 minutes of forming the blown film or cast film, % melt fracture (on basis of area of the film’s surface) is less than equal to 35%.

[0118] In a further aspect, the present disclosure refers to a polyethylene extruded article comprising an ethylene polymer and from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm, of a polymer processing aid that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two components selected from a polyphosphite, a polysiloxane, a polyethylene glycol, a high melt flow rate polypropylene, a high melt flow rate polybutene- 1, a metal salt of a fatty acid, a polyamide and a boron nitride.

[0119] Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of the ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly,the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.EXAMPLES

[0120] The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.Test Methods

[0121] The following methods are used to determine the properties indicated in the description, claims and examples.

[0122] Melt fracture % was measured by eye and is the fraction (based on % area) of melt fracture that was estimated visually from sample of blown film in the transverse direction, taken as a percentage of the area with noticeable, characteristic melt fracture streaks or roughness in the machine direction.

[0123] Melt index (MI), high load melt index (HLMI) was measured per ASTM D-1238 or ISO 1133-1, 2.16 kg (melt index) or 21.6 kg (high load melt index) at 190 deg. C. Melt index ratio is HLMI divided by MI.

[0124] Density was measured per ASTM DI 505.Examples E1-E2 and Comparative Examples CE3-CE5

[0125] Blown film trials were conducted on a blown film extrusion line with extruder and die characteristics, process conditions, and temperature profile as indicated below.

[0126] Die diameter (in.): 2.5; Die gap (mil): 75; Chimney height (in): 2; Film gauge (mil): 1; Blow up Ratio: 2.5; Frostline height (in): 7; Output (Ibs / hr): 20; Line speed (fpm): 14.5; Extruder zone temps (°F): 375 / 375 / 375 / 375; Screen changer temp. (°F) 375; Die zone temps (°F): 375; and Target melt temp. (°F): 390.

[0127] The LLDPE resin used as the base resin for the blown film trials with the inventive PPAs and the comparative (control) PPA was from LyondellBasell and has a density of 0.918 g / 10 min and a MI = 1.0.

[0128] The same general process was used for blown film production for each trial run for investigating the elimination of melt fracture using different inventive PPAs and the control PPA using the above LLDPE resin. Lor each evaluation, a test timer was set to 0 and a feed test resin (LLDPE plus particular PPA for testing) was extruded at the target output rate at the process conditions indicated above. Every 10 minutes, a film sample was collected and labeled with the test PPA, date and collection time for visual inspection to determine the % of melt fracture remaining in the film at the given 10-minute interval by measuring the width of the melt fracture region in millimeters. The greater the width of the melt fracture region in millimeters (305 mm equivalent to 100% melt fracture) of the film sample, the greater the melt fracture % in the sample at a given point in time. Each test run was continued for a time period of 90 minutes. As the PPA- containing resin of each trial was fed, the melt fractures slowly began to disappear in streaks . More particularly, as the PPA was added, melt fracture-free regimes began to emerge as stripes in the machine direction of the blown film. Over time, the stripes grew in width and the melt fracture zones diminished in width, and were sometimes eventually eliminated within the 90 minute test time. Between test runs with different PPAs, the blown film extrusion system was purged.

[0129] The results of the trials with different inventive PPAs and the comparative (control) PPA are summarized in Table 1 and Figures 1.

[0130] The details for the legends of the melt fracture as a function of time tabular data and graphical data depicted in Figure 1 are as follows:

[0131] El. “V10+7005” is blend of 2% of Songnox PQ masterbatch (5% Polyphosphite masterbatch) and 2% of Tegomer H-Si 6441 P masterbatch (5% multifunctional polyester modified siloxane) in LLDPE.

[0132] E2. “V6+7005” is blend of 2% of Polyglykol 8000S PEG masterbatch (5% loaded masterbatch) and 2% of Tegomer H-Si 6441 P masterbatch (5% multifunctional polyester modified siloxane) in LLDPE.

[0133] CE3. “2% V10” is 2 wt. % of Songnox PQ polyphosphate masterbatch in LLDPE (1000 ppm active).

[0134] CE4. “4%V10” is 4 wt. % of Songnox PQ polyphosphate masterbatch in LLDPE (2000 ppm active).

[0135] CE5. “Control” is 1300 ppm of 3M Dynamar Polymer Processing Aid FX5920A (fluoropolymer processing aid) in an LLDPE (1.0 MI, 0.918 g / cc density) from LyondellBasell.Table 1

[0136] As can be seen in Figure 1, the inventive PPAs tested provided improved melt fracture performance to the LLDPE blown film within 90 minutes. In particular, the blend of the polyphosphite PPA and the silicone PPA (2% V-10 & 2% 7005) and the blend of the PEG PPA and polysiloxane PPA (2% V-6 & 2% 7005) were very effective in improving melt fracture % of the LLDPE blown films.Examples E6-E10 and Comparative Examples CE11-CE13

[0137] Masterbatches containing fluorine-free PPA additives according to the present disclosure and LDPE as carrier resin were prepared on a ZSK 26 (Coperion) twin screw extruder. Formulations are reported in Table 2a and 2b.

[0138] Evaluation trials were carried out on a 5-layer blown film coextrusion line (Polyrema) with extruder and die characteristics, process conditions, and temperature profile as indicated below.

[0139] Die gap: 1mm; lay flat: ca. 375mm; line speed: lOm / min; output: ca. 30 kg / h. Die diameter: 100mm; film gauge: 100pm; blow up ratio: 2,4; extruder zone temp (outer layers): 65 / 195 / 200 / 205 / 210 / 215 / 215°C; extruder zone temp (inner layers): 50 / 175 / 180 / 180 / 180 / 180 / 180 °C; die temp: 215 / 215 / 215°C.

[0140] The masterbatch containing the fluorine-free PPA was added to the innermost and the outermost layer of the 5-layer blown film. Total film thickness: 100 microns.

[0141] The ethylene polymer used as base resin for the innermost and outermost layer was a 70 / 30 (wt / wt) blend of Sabie® 726NE, a butene LLDPE having MFR of 0.7 g / lOmin (ISO 1133, 190°C / 2.16kg), and a LyondellBasell LDPE having MFR of 2.0 g / lOmin (ISO 1133, 190°C / 2.16kg). The same LyondellBasell LDPE having MFR of 2.0 g / lOmin (ISO 1133, 190°C / 2.16kg) was used for the three remaining inner layers.

[0142] For each evaluation, a feed test resin containing no PPA in the innermost and outermost layer was extruded. Process parameters were adjusted to have the entire surface of the film sample covered with ridge-like distortions corresponding to 100% melt fracture (100% in Table 2a and 2b). A tester timer was set to 0. The feeding of the PPA- containing pelletized masterbatch was to the innermost and the outermost layer of the film (the ones in contact with the die walls) was started. Every 15 minutes, a film sample 75x20cm was collected and visually inspected to determine % of melt fracture in the film by measuring the width of the melt fracture region in millimeters. The greater the width of the melt fracture region in millimeters of the film sample, the greater the melt fracture % in the sample at a given point in time. Each test run was continued for a time period of 60 minutes. As the PPA-containing resin of each trial was fed, the melt fractures slowly began to disappear. Between test runs with different PPAs, the blown film extrusion system was purged.Table 2aTable 2b

[0143] LDPE: Lupolen 3020H by LyondellBasell, a low density polyethylene having melt index 2.0 g / lOmin (190°C / 2.16kg).

[0144] PEG8000: Polyglykol 8000 S, supplied by Clariant, having molecular weight Mw of8,000 g / mol.

[0145] TEGOPREN: Tegopren® 6877 by Evonik, an organo-modified siloxane.

[0146] SILIMER: Silimer™ 5140 marketed by Chengdu Silike Technology Co., Ltd, a polyester modifies silicone.

[0147] EMA: Elvaloy AC 1224 by Dow, an ethylene-methyl acrylate copolymer having melt flow rate of 2.0 g / lOmin (ISO 1133, 190°C / 2.16kg).

[0148] ANTIOX: a 50 / 50 (wt / wt) blend of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (AO 1010) and tris(2,4-ditert-butylphenyl) phosphite (AO 168).

[0149] As can be seen in Figure 2, the inventive PPAs tested provided improved melt fracture performance to the LLDPE blown film within 60 minutes.

Claims

CLAIMSWhat is claimed is:

1. Polyethylene composition comprising an ethylene polymer and from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm, of a polymer processing aid (PPA) that is substantially free of fluorine- containing compounds, wherein the polymer processing aid is a blend of at least two components selected from polyphosphites, polysiloxanes, polyethylene glycols, high melt flow rate polypropylenes, high melt flow rate polybutenes-1, metal salts of a fatty acid, polyamides and boron nitrides.

2. The polyethylene composition according to claim 1, wherein the ethylene polymer is selected from the group consisting of LDPE, LLDPE, MDPE, HDPE, elastomeric copolymers of ethylene with one or more alpha-olefins, copolymers of ethylene with a vinyl ester comonomer, and combinations thereof, preferably the ethylene polymer is a metallocene-catalyzed LLDPE, a Ziegler-Natta LLDPE, an LDPE or a combination thereof.

3. A polyolefin masterbatch comprising a carrier resin and from 1 wt.% to 50 wt.%, preferably from 2 wt.% to 20 wt.%, more preferably from 3 wt.% to 15 wt.% based on the weight of the polyolefin masterbatch, of a polymer processing aid that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two components selected from a polyphosphite, a polysiloxane, a polyethylene glycol, a high MFR polypropylene, a high MFR polybutene- 1, a metal salt of a fatty acid, a polyamide and a boron nitride.

4. The polyolefin masterbatch of claim 3, wherein the carrier resin is an olefin polymer, preferably selected from the group consisting of LLDPE, LDPE, MDPE, HDPE, polypropylene, like copolymers and terpolymers of ethylene, propylene and butylene, and combinations thereof.

5. The polyethylene composition according to any one of claims 1-2 or the polyolefin masterbatch according to any one of claims 3-4, wherein the polymer processing aid is a blend of two components and the weight ratio between the components in the blend ranges from 90: 10 to 50:50, preferably from 85:15 to 55:45, more preferably from 80:20 to 70:30.

6. The polyethylene composition according to any one of claims 1-2 or the polyolefin masterbatch according to any one of claims 3-4, wherein the polymer processing aid is a blend of two components and the weight ratio between the components in the blend is 20:80, or 30:70, or 40:60, or 50:50, or 60:40, or 70:30, or 80:20.

7. The polyethylene composition or the masterbatch composition according to any one of the preceding claims, wherein the polymer processing aid is a two-component blend selected from polysiloxane and polyethylene glycol blends, polyphosphite and polysiloxane blends, and high melt flow rate polybutene- 1 and polyethylene glycol blends.

8. The polyethylene composition or the masterbatch composition according to claim 7, wherein the polymer processing aid is a blend of a polysiloxane and a polyethylene glycol, wherein the polysiloxane is a polyester modified silicone and the polyethylene glycol has molecular weight of less than 40,000 g / mol, preferably ranging from 1,500 to 35,000 g / mol, more preferably from 5,000 to 20,000 g / mol, still more preferably from 5,000 to 12,000 g / mol, particularly preferably from 6,000 to 12,000 g / mol.

9. The polyethylene composition or the masterbatch composition according to claim 7, wherein the PPA is a blend of high melt flow rate polybutene- 1 and polyethylene glycol, wherein the high melt flow rate polybutene has melt flow rate ranging from 100 to 2,000 g / 10 min, more preferably from 200 to 1,500 g / 10 min, measured by ISO 1133-1 (190°C / 2.16 kg) and the polyethylene glycol has molecular weight of less than 40,000 g / mol, preferably ranging from 1,500 to 35,000 g / mol, more preferably from 5,000 to 20,000 g / mol, still more preferably from 5,000 to 12,000 g / mol, particularly preferably from 6,000 to 12,000 g / mol.

10. The polyethylene composition or the masterbatch composition according to claim 7, wherein the PPA is a blend of a polyphosphite and a polysiloxane blend, wherein the weight ratio of the polyphosphite to the polysiloxane is from 80:20 to 20:80, more preferably is 50:50.

11. A process to prepare a polyethylene extruded article comprising:(i) providing a polyethylene composition comprising an ethylene polymer and from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm, of a polymer processing aid, wherein the polymer processing aid is substantially free of fluorine- containing compounds and is a blend of at least two components selected from a polyphosphite, a polysiloxane, a polyethylene glycol, a high melt flow rate polypropylene, a high melt flow rate polybutene-1, a metal salt of a fatty acid, a polyamide and a boron nitride; and(ii) extruding the polyethylene composition into the polyethylene extruded article.

12. A method of decreasing melt fracture in a polyethylene extruded article, comprising extruding an ethylene polymer into a polyethylene extruded article on an extrusion line; and blending into the extrusion line a polymer processing aid that is substantially free of fluorine-containing compounds to provide a polyethylene extruded article comprising from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm, of the polymer processing aid, wherein the polymer processing aid is substantially free of fluorine-containing compounds and is a blend of at least two components selected from a polyphosphite, a polysiloxane, a polyethylene glycol, a high melt flow rate polypropylene, a high melt flow rate polybutene-1, a metal salt of a fatty acid, a polyamide and a boron nitride.

13. A polyethylene extruded article comprising an ethylene polymer and from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm, of a polymer processing aid that is substantially free of fluorine-containing compounds, wherein the polymer processing aid is a blend of at least two components selected from a polyphosphite, a polysiloxane, a polyethylene glycol, a high melt flow ratepolypropylene, a high melt flow rate polybutene- 1, a metal salt of a fatty acid, a polyamide and a boron nitride.

14. The process of claim 11 or the method of claim 12 or the polyethylene extruded article of claim 13, wherein the polyethylene extruded article is a blown or cast film, a pipe or a wire and cable sheath or covering, the polyethylene extruded article is a LLDPE blown film or cast film.

15. The process of claim 11, wherein in step (i) the polyethylene composition is provided by blending into the extrusion line an ethylene polymer and a polymer processing aid to provide from 100 ppm to 10,000 ppm, preferably from 200 ppm to 8,000 ppm, more preferably from 300 ppm to 5,000 ppm, of the polymer processing aid in the polyethylene composition, wherein the polymer processing aid is that is substantially free of fluorine- containing compounds and is a blend of at least two compounds selected from a polyphosphite, a polysiloxane, a polyethylene glycol, a high MFR polypropylene, a high MFR polybutene- 1, a metal salt of a fatty acid, a polyamide, or a boron nitride.

16. The process of claim 15 or the method of claim 12, wherein the polymer processing aid is directly blended into the extrusion line or blended into the extrusion line as a masterbatch.

17. The method of claim 12, wherein the polyethylene extruded article is a LLDPE blown film or cast film, and the LLDPE blown film or cast film is such that at 90 minutes of forming the blown film or cast film, % melt fracture, on basis of area of the film’s surface, is less than equal to 35%.

Images