Poly (vinyl ester) polymer processing aids for polyolefins

Abstract

The present invention relates to polymeric processing aid compositions for polyolefins, methods of their manufacture and articles made from the compositions, and the use of the compositions for removing or reducing sharkskin melt rupture or reducing die lip build-up formation. The compositions of the present invention may also be substantially free of fluorine and, in some embodiments, substantially free of siloxanes.

Description

TECHNICAL FIELD

[0001] The present invention relates to the use of poly(vinyl esters) as polymer processing aids (PPAs) in thermoplastic extrusion, including polyolefin film extrusion. BACKGROUND

[0002] Industrial polyolefin melt processes, including blown film, cast film, sheet extrusion, profile extrusion, blow molding, wire and cable extracoating, and fiber spinning, require high throughput to reduce the costs associated with such processing. However, increasing the polyolefin extrusion rate above a critical wall shear stress leads to the onset of flow instabilities, which manifest themselves as distortions in the extruded product. Polymer Processing Additives for Melt Fracture Control in Applied Polymer Rheology: Polymeric Fluids with Industrial Applications, 1sted., pp. 29-58, Hatzikiriakos, S.G., & Migler, K.B. (2012) describes a range of melt extrusion instabilities observed in industry. Above a critical volumetric flow rate, polyolefin extrudates exhibit distortions that increase in severity as the flow rate increases. These distortions are collectively referred to as "melt fracture." Above a first critical shear stress, the polyolefin extrudates exhibit "surface melt fracture," also known as "sharkskin." Sharkskin manifests itself as a regular pattern of surface roughness that leads to haze, which is undesirable and limits the extrusion rate. Extruding at still higher rates leads to stick-slip instabilities or "oscillatory melt fracture." Extruding at even higher rates leads to gross irregular distortions in the extrudate, referred to as "gross melt fracture."

[0003] "Polymer processing aids" ("PPAs") are well known to those skilled in the art of polyolefin extrusion and film processing. The addition of low concentrations of PPA to polyolefin melts increases the critical shear stress at which sharkskin occurs, thereby allowing higher throughput rates without the appearance of sharkskin. To date, fluoroelastomers and fluoroplastics (collectively referred to as "fluoropolymers") have been the proven PPA solution to sharkskin in polyolefin extrusion processes.

[0004] U.S. Patent No. 3,125,547 discloses a composition having 0.005-2 wt% of a fluoropolymer in a polyolefin. The composition is effective in removing sharkskin from film and tube extrudates compared to extrudates of the same polyolefin in the absence of the fluoropolymer.

[0005] U.S. Patent No. 4855360 discloses polyolefin compositions containing a combination of a small amount of a fluoropolymer with a poly(oxyalkylene) polymer. The preferred poly(oxyalkylene) polymer disclosed is polyethylene glycol (PEG; CAS#: 25322-68-3) having a molecular weight of 1000-20000 g / mol. Such compositions show a synergistic effect of the poly(oxyalkylene) with the fluoropolymer of the invention. The examples of the document show that the combination of the fluoropolymer and PEG shifts the onset of melt fracture to a higher shear rate than either the fluoropolymer or PEG alone, reduces the time to remove melt fracture at a given apparent shear rate in blown film processing, and reduces the pressure drop across a blown film die. The composition allows for the use of less fluoropolymer with poly(oxyalkylene) than the use of fluoropolymer alone.

[0006] U.S. Patent No. 6642310 discloses improving PPA efficiency by using dispersed fluoropolymer particles having a minimum particle size of 2 microns and using an interfacial agent to help achieve the target particle size. Silicone-polyether, aromatic polyester, and aliphatic polyesters (including polylactic acid (PLA) and polycaprolactone (PCL; CAS#: 24980-41-4)) and other materials are disclosed as useful interfacial agents. The use of PCL as an interfacial agent is disclosed, which has improved temperature resistance compared to poly(oxyalkylene).

[0007] Fluoropolymer PPA, typically formulated in combination with a synergist, is effective at low concentrations. Such compositions can reduce extrusion pressure and extruder torque at a given output, in addition to delaying sharkskin onset to higher extrusion rates, and can help reduce die lip build-up (also known as die drool). However, the use of fluoropolymers as polymer processing aids is now undesirable due to regulatory and market development needs to remove per- and poly-fluoroalkyl substances (“PFAS”) from polyolefins. Therefore, there is a need for fluorine-free alternatives to PPA to eliminate sharkskin melt fracture.

[0008] U.S. Patent No. 4535113 discloses a composition of a polyolefin and a silicone additive. The silicone additive is a poly(dimethylsiloxane) (“PDMS”) copolymer in which the comonomer is a siloxane substituted with at least one pendant oxirane, vicinal epoxy, or amino group in a concentration sufficient to improve optical or mechanical properties. The composition shows reduced melt fracture and pinstriping when the silicone additive is present at 0.05% of the composition.

[0009] U.S. Patent No. 5789473 discloses polyolefin compositions containing 0.01-1 wt% of a hydroxy-functional diorganosiloxane having a molecular weight of at least 40,000 g / mol. The formulations of this patent show reduced surface roughness of films produced on a slit die compared to controls without PPA additive and compared to conventional fluoroelastomer PPA.

[0010] Silicones and poly(dialkylsiloxane) copolymers are effective replacements for fluoroelastomers as PPA for the removal or delay of sharkskin melt fracture in polyolefins. However, some applications now require alternatives that do not contain siloxanes. Therefore, there is a need for non-fluorinated, non-silicone containing alternative PPA to eliminate sharkskin melt fracture.

[0011] U.S. Patent No. 10982079B2 discloses the use of poly(oxaalkylene) polymers having a molecular weight of at least 50,000 g / mol, optionally with a second poly(oxaalkylene) polymer having a molecular weight of up to 20,000 g / mol and a metal salt of a carboxylic acid, sulfonic acid or alkylsulfate salt. The use of certain metal salts was demonstrated to improve the thermal stability of the poly(oxaalkylene) polymer. The examples show that high molecular weight PEG is effective in eliminating melt fracture with zinc stearate at a concentration of 300-1200 ppm in polyethylene. The inclusion of a second, lower molecular weight PEG improves performance. The disclosed formulations are not as effective as fluoroelastomer PPA in eliminating melt fracture. There is no disclosure of the effect of PEG on specific output (output / RPM) of the extruder and film properties.

[0012] U.S. Patent Application 2023 / 003100 Al discloses the use of 200-10,000 ppm of a sorbitan or polysorbate ester in combination with one or both of a fatty acid metal salt and a PEG having a molecular weight of less than 40,000 g / mol as a PPA for polyolefins. The examples disclose the use of polysorbate 60 in combination with one or both of zinc stearate and a PEG having a molecular weight of 8,000 g / mol and demonstrate their performance in a blown film elimination time study. The inventors disclose that the output rate variation is 30% or less and there is no disclosure of the effect of the formulation on specific output of the extruder or extrusion stability.

[0013] The above-disclosed documents show that PEG, stearate salts and polysorbate esters are effective in eliminating sharkskin. However, it is known that the use of stearate salts contributes to die lip build-up and can affect printability on polyolefin films when used at high levels. High levels of PEG can also contribute to die lip build-up and printability issues.

[0014] U.S. Patent 5,707,569 discloses the use of extrusion aids containing polar pendant groups in extrudable compositions containing stearates for fluoropolymer processing aids. Such aids include poly(vinyl acetate) (“PVAc”) and poly(ethylene-co-vinyl acetate) (“PEVA”). The aids are used to counteract the deleterious effects of stearates in compositions containing fluoropolymer processing aids. The specification states and the examples show that the elimination of melt fracture cannot be attributed solely to the aids. That is, the invention shows that PVAc and PEVA should not be used as polymer processing aids in the absence of fluoropolymers and thus teaches away from the invention.

[0015] WO 2024147358 discloses the use of biopolymer polymer processing aids including poly(lactic acid) and poly(succinyl butylene) glycol). Such biopolymers show more effective reduction of die lip build-up (DLBU) when used in combination with additional additives, including poly(ethylene-co-vinyl alcohol) (“PEVOH” or more commonly “EVOH”) in particular. The biopolymers, including PLA, are not used in combination with any poly(vinyl ester), including poly(ethylene-co-vinyl acetate) or poly(vinyl acetate). The inventors teach that the biopolymer preferably constitutes the majority component of the PPA composition when used in combination with another additive.

[0016] There is a need for PPA that is substantially fluorine-free, siloxane-free to eliminate sharkskin melt fracture. There is also a need for such PPA to minimize any reduction in extruder output due to slip or surge of the extrusion screw. Ideally, such PPA would increase the specific output of the extruder due to a reduction in pressure across the die without causing screw slip. There is also a need for such PPA to minimize the formation of die lip build-up during extrusion and have minimal negative impact on the physical properties of the film, including printability.

[0017] Objectives of the Invention

[0018] Regulatory and market development needs call for alternatives to fluoropolymer and organosilicon PPA. There is a need for polymer processing aids for polyolefins that are substantially fluorine-free, siloxane-free that can delay the onset of sharkskin melt fracture to higher extrusion rates. There is also a need for PPA to reduce the formation of die lip build-up. An additional requirement for such non-fluorinated PPA is to be effective at low concentrations. In food contact applications, there is also a requirement for the PPA to comply with food contact regulations in the jurisdiction in which it is sold. The PPA of the present invention meets one or more of these objectives. SUMMARY

[0019] The present invention relates to polymer processing aid compositions for polyolefins, methods of making the same, and articles made from the compositions, and the use of the compositions to remove or reduce sharkskin melt fracture or reduce die lip build-up formation. The compositions of the invention are also substantially free of fluorine, and in some embodiments, substantially free of siloxane.

[0020] The present invention provides the use of a poly(vinyl ester) or vinyl ester copolymer as a polymer processing aid to remove or reduce sharkskin melt fracture formation, or to reduce die lip build-up formation in a polyolefin composition, wherein the polymer processing aid is used in an amount of 0.01 to 1.0 weight %, based on the total weight of the polyolefin composition, with the proviso that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content is greater than 60 weight %, and wherein the polymer processing aid is substantially free of PFAS. Suitably, the poly(vinyl ester) or vinyl ester copolymer can be used in an amount of 0.01 to 0.7 weight %, preferably in an amount of 0.02 to 0.5 weight %, and more preferably in an amount of 0.02 to 0.2 weight %, based on the total weight of the polyolefin composition.

[0021] In another aspect, the present invention provides a method of removing or reducing sharkskin formation, or reducing die lip build-up formation in a polyolefin extrusion process, comprising using a poly(vinyl ester) or vinyl ester copolymer as a polymer processing aid, wherein the polymer processing aid is used in an amount of 0.01 to 1.0 weight %, based on the total weight of the polyolefin composition, with the proviso that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content is greater than 60 weight %, and wherein the polymer processing aid is substantially free of PFAS. Suitably, the poly(vinyl ester) or vinyl ester copolymer can be used in an amount of 0.01 to 0.7 weight %, preferably in an amount of 0.02 to 0.5 weight %, and more preferably in an amount of 0.02 to 0.2 weight %, based on the total weight of the polyolefin composition.

[0022] In still another aspect, the present application provides a composition comprising a polyolefin; and 0.01 to 1.0 weight % (of the total composition) of a polymeric processing aid, wherein the polymeric processing aid comprises a poly(vinyl ester) or vinyl ester copolymer, with the proviso that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content is greater than 60 weight %, and wherein the polymeric processing aid is substantially free of PFAS. Suitably, the poly(vinyl ester) or vinyl ester copolymer can be present in an amount of 0.01 to 0.7 weight %, based on the total weight of the polyolefin composition. Preferably, the poly(vinyl ester) or vinyl ester copolymer can be present in an amount of 0.02 to 0.5 weight % and more preferably in an amount of 0.02 to 0.2 weight %, based on the total weight of the polyolefin composition.

[0023] Also provided is a masterbatch composition comprising a polyolefin; and 1 to 45 weight % (of the total composition) of a polymeric processing aid, wherein the polymeric processing aid comprises a poly(vinyl ester) or vinyl ester copolymer, with the proviso that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content is greater than 60 weight %, and wherein the masterbatch is substantially free of PFAS. Suitably, the poly(vinyl ester) or vinyl ester copolymer can be present in an amount of 1.5 to 40 weight %, or 2 to 30 weight %, for example 2 to 10 weight %, based on the total weight of the polyolefin composition.

[0024] The above use, method or composition can further comprise the use of a polyester or ester copolymer as an additional component of the polymeric processing aid, wherein the total amount of the poly(vinyl ester) or vinyl ester copolymer, and the polyester or ester copolymer is 0.01 to 1 weight %, based on the total weight of the olefin composition. The polyester or ester copolymer can have a lower viscosity than the poly(vinyl ester) or vinyl ester copolymer. The viscosity of the polymers can be measured by capillary or rotational rheometers known in the art at a range of shear rates and temperatures, but can also be easily assessed by melt flow rate (MFR, ASTM D 1238) measurements at a single condition. Higher MFR indicates lower viscosity. The MFR of the polyester or ester copolymer can be at least 5% higher, suitably 10% higher, and preferably at least 20% higher, when measured under the same standard ASTM D 1238 test conditions as the poly(vinyl ester) or vinyl ester copolymer.

[0025] In some embodiments, the PPA based on poly(vinyl ester) or vinyl ester copolymers is present in the polyolefin composition at an amount of about 0.01-1% by weight. Such compositions are extrudable compositions that can be used in polyolefin extrusion processes, including blown film, cast film, sheet extrusion, profile extrusion, pipe extrusion, wire and cable extrusion, and extrusion blow molding. They can be used in the final extrusion process to remove or delay the appearance of sharkskin and reduce die lip buildup or reduce pressure drop across the extrusion die. Compared to polyolefins without PPA based on poly(vinyl ester) or vinyl ester copolymers, such compositions can be used to remove sharkskin or delay sharkskin to higher extrusion flows under given shear rate conditions. In other embodiments, the PPA is present in the carrier polymer at an amount of about 1-45% by weight, for example 1.5-40% by weight, preferably 2-30% by weight, for example 2-10% by weight. Compositions in higher concentration ranges (referred to as masterbatches) can be used as intermediate materials for preparing the final extrudable composition. These uses are well known to those skilled in the art.

[0026] The molecular weight of the poly(vinyl ester) or vinyl ester copolymer may be greater than 1000 g / mol. Suitably, the molecular weight of the poly(vinyl ester) or vinyl ester may be greater than 5000 g / mol, preferably greater than 10000 g / mol, for example greater than 50000 g / mol, or greater than 100000 g / mol, or greater than 200000 g / mol, or greater than 300000 g / mol.

[0027] In some embodiments, the poly(vinyl ester) or vinyl ester copolymer is a poly(vinyl acetate) homopolymer (“PVAc”). Suitably, the PVAc may have a molecular weight greater than 5000 g / mol, preferably greater than 10000 g / mol, for example greater than 50000 g / mol, or greater than 100000 g / mol, or greater than 200000 g / mol, or greater than 300000 g / mol.

[0028] In some embodiments, the poly(vinyl ester) or vinyl ester copolymer is a vinyl acetate (“VA”) copolymer. In some embodiments, the VA copolymer may be a poly(ethylene-co-vinyl acetate) (“PEVA”) copolymer containing more than 30% by weight of vinyl acetate, for example, more than 35%, or more than 40%, or more than 50%, or more than 60%, or more than 70%, or more than 80%, or more than 90% vinyl acetate. In other words, vinyl acetate monomer units may constitute more than 30% (or more than 35%, or more than 40%, or more than 50%, or more than 60%, or more than 70%, or more than 80%, or more than 90%) of the weight of the poly(ethylene-co-vinyl acetate) (“PEVA”) copolymer, with the remainder being ethylene comonomers.

[0029] In some embodiments, the polyester or ester copolymer may be poly(lactic acid) (“PLA”). The poly(lactic acid) may contain more than 80% of the L-isomer of lactic acid or lactide monomers.

[0030] In some embodiments, the polyester or ester copolymer may be a poly(hydroxyalkanoate) (“PHA”).

[0031] The poly(vinyl ester) or vinyl ester copolymer and the polyester or ester copolymer may be present in the polymer processing aid in a weight ratio of about 1:10 to about 10:1. Preferably, the poly(vinyl ester) or vinyl ester copolymer and the polyester or ester copolymer are present in a ratio of about 1:3 to about 10:1, more preferably in a ratio of about 1:1 to about 8:1, and most preferably in a ratio of 1:1 to 5:1.

[0032] The polymer processing aid can be dispersed in the polyolefin composition with an average particle size of 0.2-30 micrometers, more preferably 0.5-20 micrometers, even more preferably 1-15 micrometers, and most preferably 1-10 micrometers.

[0033] One or both of the poly(vinyl ester) or vinyl ester copolymer and the polyester or ester copolymer may have a linear or nonlinear structure. The poly(vinyl ester) or vinyl ester copolymer and the polyester or ester copolymer may be branched by adding a chain extender or by free radical-mediated chemistry.

[0034] The polyolefin may be selected from polyethylene, including high-density polyethylene, linear low-density polyethylene or low-density polyethylene, or polypropylene, including homopolymer polypropylene, random copolymer polypropylene or multiphase impact copolymer polypropylene, or combinations thereof.

[0035] In some embodiments, the polyester or ester copolymer may be selected from poly(lactic acid), polyhydroxyalkanoate, polyhydroxyalkanoate copolymer, or poly(butylene terephthalate). Preferably, the polyester or polyester copolymer is poly(lactic acid), polyhydroxyalkanoate, or polyhydroxyalkanoate copolymer. The polyester or ester copolymer may be polyhydroxyalkanoate, polyhydroxyalkanoate copolymer, or poly(butylene terephthalate).

[0036] Polyesters and ester copolymers that can be used in the PPA of this invention include aliphatic polyesters, aromatic polyesters and copolymers of aliphatic or aromatic polyesters.

[0037] Aliphatic polyesters and aliphatic polyester copolymers applicable to the present invention include poly(lactic acid), poly(glycolic acid), poly(caprolactone), poly(butylene succinate), poly(butylene adipate), and various poly(hydroxyalkyl esters), including poly(4-hydroxybutyrate), poly(3-hydroxyvalerate), poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

[0038] The aromatic polyesters and aromatic polyester copolymers applicable to the present invention include poly(butylene terephthalate adipate), poly(butylene succinate-co-butylene terephthalate), and poly(butylene terephthalate-co-alkylene oxide).

[0039] The preferred polyester suitable for use in this invention is poly(lactic acid). The melt flow rate (ASTM D1238, 210°C, 2.16 kg) of the preferred PLA of this invention is 0.1-150 g / 10 min, for example 0.5-100, for example 0.5-80, for example 1-50. The MFR of the preferred PLA that can be used as the polyester of this invention is 0.5-15.

[0040] The composition may further comprise 0.01-50% by weight of a synergist, which is a poly(alkylene oxide) or polymeric liquid phosphite antioxidant with a molecular weight of 1000-20000 g / mol. The poly(alkylene oxide) may be polyethylene glycol. The molecular weight of the poly(alkylene oxide) may be 2000-10000 g / mol.

[0041] In some embodiments, the synergist is present at a concentration of 0.01-0.5%, preferably 0.01-0.2%, which is suitable as an extrudable composition for use in polyolefin extrusion processes. In other embodiments, the synergist is present at a concentration of 1-50%, preferably 5-25%, which is suitable as a masterbatch.

[0042] The composition may further comprise 0.01-10% boron nitride in the total composition. The average particle size of the boron nitride is preferably less than 30 micrometers, and more preferably less than 10 micrometers. In some applications of the invention, the concentration of boron nitride used is as low as 0.01-0.2%, preferably 0.01-0.1%, making such embodiments suitable as extrudable compositions for polyolefin extrusion processes. In other embodiments, boron nitride is present at a concentration of 0.5-50%, preferably 0.5-10%, making such embodiments suitable as masterbatches.

[0043] The composition containing linear polyolefins may further comprise 0.1-50% low-density polyethylene (LDPE) in the total composition. This LDPE may be present in the extrudable composition in an amount of 0.1-15%, suitably 0.1-5%, preferably 0.1-0.5%. This LDPE may be present in the masterbatch in an amount of 5-99%, suitably 5-40%, preferably 10-35%, wherein the remainder of the carrier resin is a linear polyolefin; or the LDPE may be used as the sole carrier resin of the PPA masterbatch.

[0044] The present invention also provides extruded polyolefin products produced using the above-described composition or method.

[0045] The fluorine-free and siloxane-free compositions of the present invention can be used in polyolefin conversion processes to remove, reduce, or delay the occurrence of melt fracture to achieve higher yields. These polyolefin conversion processes include extrusion, particularly blow molding and cast film extrusion, profile extrusion, extrusion blow molding, and fiber spinning. The compositions can also be used to reduce extrusion pressures in various extrusion processes, including blow molding and cast film extrusion, profile extrusion, extrusion blow molding, and fiber spinning. The compositions can also be used to reduce die lip buildup in various extrusion processes. Detailed Implementation

[0046] This invention relates to polyolefin compositions exhibiting improved extrusion properties. The invention also relates to methods for manufacturing the polyolefin compositions and articles made from the polyolefin compositions.

[0047] In another aspect, it relates to a polymer processing aid (PPA) comprising a poly(vinyl ester) or vinyl ester copolymer for improving the extrusion properties of a polyolefin composition. In another aspect, it relates to a polymer processing aid (PPA) comprising a blend of a poly(vinyl ester) or vinyl ester copolymer with a polyester or ester copolymer for improving the extrusion properties of a polyolefin composition. In another aspect, it relates to the use of a PPA comprising a synergist and a poly(vinyl ester) or vinyl ester copolymer for improving the extrusion properties of a polyolefin composition. In another aspect, it relates to the use of a PPA comprising boron nitride and a poly(vinyl ester) or vinyl ester copolymer for improving the extrusion properties of a polyolefin composition. In yet another aspect, it relates to a masterbatch that can be used to accurately and quantitatively deliver a PPA to a polyolefin composition.

[0048] The details of the invention shown herein are by way of example. They are intended to illustrate different embodiments of the invention and are not intended to limit the scope of the invention.

[0049] The following are brief (not exhaustive) conventional definitions known in the art, some of which may be helpful in explaining the invention.

[0050] A “masterbatch” is a concentrated mixture of pigments and / or additives that is encapsulated or dissolved in a carrier polymer during heating and mixing, and then cooled and cut into granular shapes. Masterbatch can be added to a base polymer to deliver a desired concentration of pigment or additive to the base polymer.

[0051] "Base polymer" refers to a polymer that is to be colored, functionalized, stabilized, or modified by additives or masterbatches. This may also be referred to by those skilled in the art as "letdown resin".

[0052] "Carrier polymer" is a polymer or polymer blend that, when combined with fillers, colorants, or additives, encapsulates them to form a masterbatch.

[0053] In the RSC publication "Compendium of Polymer Terminology and Nomenclature, IUPAC Recommendations, 2008" (hereinafter referred to as the IUPAC Compendium), a "polymer" is defined as a polymer derived from more than one monomer.

[0054] "Die lip buildup" (DLBU) is the accumulation of extruded material at the exit of the extrusion die ("die lip").

[0055] Melt flow rate (MFR) is as defined in ASTM D 1238-20. The unit of measurement is grams per 10 minutes.

[0056] Melt volumetric rate (MVR) is defined as in ASTM D 1238-20. The unit of measurement is cm. 3 / 10 minutes.

[0057] "Polar functional group" refers to a functional group containing two atoms with an electronegativity difference of 0.4-1.7 on the Pauling scale.

[0058] "Substantially free" in relation to polymer or polymer additive content means levels below those intentionally included in the polymer composition. It also means levels where unintentional addition is still permissible. Furthermore, it means levels where trace amounts of less than 10 ppm, and preferably less than 1 ppm, are permissible.

[0059] All percentages mentioned in this document are percentages based on the weight of the total composition.

[0060] The following compositions are disclosed herein:

[0061] a. Polyolefins, and

[0062] b. 0.01-1.0% by weight of a polymer processing aid (of the total composition), wherein the polymer processing aid comprises a poly(vinyl ester) or a vinyl ester copolymer, provided that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content of the copolymer is greater than 30% by weight.

[0063] The composition may further comprise polyester or ester copolymer.

[0064] The composition may further include optional synergists selected from poly(alkylene oxide) and polymeric liquid phosphites.

[0065] The composition may further contain boron nitride.

[0066] The following masterbatch compositions were also disclosed:

[0067] a. Polyolefins, and

[0068] b. 1-45% by weight of a polymer processing aid (of the total composition), wherein the polymer processing aid comprises a poly(vinyl ester) or a vinyl ester copolymer, provided that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content of the copolymer is greater than 30% by weight.

[0069] The masterbatch composition may further contain polyester or ester copolymer.

[0070] The masterbatch composition may further include optional synergists selected from poly(alkylene oxide) and polymeric liquid phosphites.

[0071] The masterbatch composition may further contain boron nitride.

[0072] The masterbatch composition may further contain 1-95% of additional polymer additives, including hindered phenolic antioxidants, phosphite antioxidants, catalyst neutralizers (including metal carboxylates, hydrotalcites, or zinc oxide), antiblocking agents, slip agents, antistatic agents, and pigments. Such a masterbatch composition can be used to deliver the combination of said polymer processing aids and other polymer additives to a polyolefin extrudable composition.

[0073] Polyolefins

[0074] The polyolefins suitable for the compositions include linear or branched polyolefins. In particular, polyolefins that can be used in the present invention include polypropylene, high-density polyethylene, linear low-density polyethylene, medium-density polyethylene, polybutene, copolymers thereof, and include ethylene-vinyl acetate copolymers, acid copolymers (including ethylene-methacrylic acid and ethylene-acrylic acid copolymers), and combinations thereof. Such polyolefins can be prepared by any means known in the art, including free radical high-pressure processes and via catalytic processes, including those using chromium catalysts, Ziegler-Natta catalysts, and single-point catalysts (including metallocene catalysts).

[0075] In some embodiments, the polyolefin may comprise a substantially linear polyolefin or α-olefin copolymer. Suitably, the polyolefin may have a density of 0.91-0.965 g / cm³. 3 It is essentially linear polyethylene or polyethylene copolymer.

[0076] In some embodiments, the polyolefin contains a density of about 0.91-0.925 g / cm³. 3Linear low-density polyethylene (LLDPE). This can be selected from butene, hexene, octene, or other low (short chain) α-olefin copolymers of polyethylene. Examples of such LLDPEs include LyondellBasell Petrothene GA 502024 and ExxonMobil Chemical Company LL 1001X31. Narrow molecular weight distribution (Mw / Mn < 3, e.g., less than 2) and low melt flow rate (MFR < 2 g / 10 min) linear low-density polyethylene copolymers are known to readily produce a sharkskin effect and can benefit from the use of the polymer processing aid compositions of the present invention. In particular, narrow molecular weight distribution and low melt flow rate (MFR < 2 g / 10 min) metallocene linear low-density polyethylene copolymers are known to be particularly prone to producing a sharkskin effect and can benefit from the use of the PPA compositions of the present invention.

[0077] In some embodiments, the polyolefin contains a density of about 0.925-0.940 g / cm³. 3 Medium-density polyethylene (MDPE). This can be selected from butene, hexene, or other low-alpha-olefin copolymers of polyethylene.

[0078] In some embodiments, the polyolefin contains a density equal to or greater than about 0.940 g / cm³. 3 High-density polyethylene (HDPE). This can be selected from butene, hexene, or other low-alpha-olefin copolymers of polyethylene. It can also be homopolymer HDPE.

[0079] In some embodiments, the polyolefin may contain a density of about 0.91-0.94 g / cm³. 3 Branched low-density polyethylene (LDPE). LDPE is not particularly prone to sharkskin melt defects, but it is frequently blended with linear polyolefins in the compositions of this invention. The LDPE of this invention includes LyondellBasell Petrothene NA 219000.

[0080] In some embodiments, the polyolefin may be a blend of polyolefins. Polyolefin blends can be used to impart specific properties to the final polyolefin article. In some embodiments, the polyolefin may be a blend comprising a lower-density plasmon or elastomer component. Such lower-density polyolefins can be used to impart specific properties, including toughness or sealing properties for membrane applications.

[0081] In some embodiments, the polyolefin may be polypropylene. Such polypropylene may include homopolymer polypropylene (hPP), random copolymer polypropylene (RCP), impact copolymer polypropylene (ICP), or blends thereof. Examples of polypropylene of the present invention include Braskem FF 030F2. Although polypropylene is typically not prone to sharkskin melt fracture, it can exhibit die lip buildup and can benefit from the polymer processing aids of the present invention in reducing die lip buildup.

[0082] Poly(vinyl ester)

[0083] The poly(vinyl ester) or vinyl ester copolymers that can be used in this invention include those represented by Formula 1:

[0084] Formula 1

[0085] Where m is 0, 1, or greater, and where R 1 It is an alkyl group containing 1-12 carbon atoms or an alkyl group containing 1-12 carbon atoms having a polar vinyl substituent, and wherein R 2 It is an alkyl group having 1-12 carbon atoms, n greater than 1, and the condition is that when m is 1 or greater and R 1 When R is ethyl, the values ​​of m and n result in the vinyl ester content of the polymer being greater than 30% by weight. 1 When it is an alkyl group, it can be linear or branched. Preferably, the alkyl group contains 1-6 carbon atoms.

[0086] Preferably, n+m results in the polymer having a molecular weight greater than 5000 g / mol, more preferably greater than 10000 g / mol, for example greater than 50000 g / mol, greater than 100000 g / mol, greater than 200000 g / mol, or greater than 300000 g / mol.

[0087] When m is 0 in Equation 1, the chemical structure can be simplified to Equation 2, which represents a poly(vinyl ester) homopolymer.

[0088] Formula 2

[0089] Examples of poly(vinyl ester) that can be used in this invention include poly(vinyl acetate), poly(vinyl propionate), poly(vinyl laurate), poly(vinyl butyrate), and poly(vinyl stearate).

[0090] Poly(vinyl acetate) is a preferred poly(vinyl ester) of the present invention. PVAc is represented by Formula 3.

[0091] Formula 3

[0092] The PVAc used in this invention has a molecular weight greater than 1000 g / mol. Suitably, the PVAc may have a molecular weight greater than 5000 g / mol, preferably greater than 10000 g / mol, for example greater than 50000 g / mol, greater than 100000 g / mol, greater than 200000 g / mol, or greater than 300000 g / mol. Examples of PVAc homopolymers that can be used in this invention include Wacker (Germany) Vinnex 2522, Vinnex 2523, Vinnex 2525, and Vinnex 2526 and Synthomer (UK) M60.

[0093] In Equation 1, R 1 However, it can be vinyl alcohol, vinyl butyral, dimethyl maleate, diethyl maleate, dibutyl maleate, vinyl laurate, crotonic acid ((2E)-but-2-enoic acid), linear alkyl (e.g., ethyl) or branched alkyl. When R 1 When the ethyl group is ethyl, the resulting vinyl acetate copolymer is called poly(ethylene-co-vinyl acetate) or PEVA, and is also commonly referred to as ethylene-vinyl acetate (EVAC or EVA) copolymer, and can be represented by Formula 4:

[0094] Formula 4

[0095] PEVA can be obtained with varying ranges of vinyl acetate (VA) content. PEVA copolymers with VA content from 4% to 28% by weight are commonly used in polyolefin films, where they are blended with polyolefins to improve properties such as seal initiation and gloss. Such PEVA with lower VA content is not included in the VA copolymers usable in this invention. PEVA copolymers with a vinyl acetate content greater than 40% and less than 100% (typically less than about 90%) refer to ethylene-vinyl acetate rubber or EVM. Such high VA content PEVA is commonly used as an adhesive or modifier in PVC. PEVA copolymers with a vinyl acetate content greater than 28%, such as greater than 30%, greater than 35%, greater than 40%, greater than 50%, greater than 60%, greater than 65%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, greater than 90%, or greater than 95%, are useful VA copolymers in this invention. Examples of VA copolymers usable in this invention include the high VA content PEVA grade Levamelt obtained from Arlanxeo (Netherlands). ® 600, Levamelt 700, Levamelt 800, Levapren 800, Levapren 900 and Levamelt 900.

[0096] Polyester

[0097] Polyesters that can be used in this invention include any polymer containing ester functional groups within or across each repeating unit of the polymer backbone. This definition should be interpreted in a non-limiting manner and includes aliphatic and aromatic polyesters and their copolymers.

[0098] Polyesters suitable for use in this invention include those represented by Formula 6:

[0099] Formula 6

[0100] Where R 4 It is a branched, linear, or cyclic alkyl group having 1-12 carbon atoms. The linear alkyl group preferably has 1-8 carbon atoms, for example, 1-5 carbon atoms. Preferably, p makes the molecular weight of the polymer greater than 1000 g / mol, more preferably greater than 10000 g / mol, for example greater than 50000 g / mol or greater than 100000 g / mol.

[0101] Polyester and ester copolymers that can be used in this invention include copolymers of aliphatic polyesters, aromatic polyesters and aliphatic or aromatic esters.

[0102] Aliphatic polyesters and aliphatic ester copolymers applicable to the present invention include poly(lactic acid), poly(glycolic acid), polycaprolactone, poly(butylene succinate), poly(butylene adipate), and various poly(hydroxyalkyl esters), including poly(4-hydroxybutyrate), poly(3-hydroxyvalerate), poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

[0103] The PLA applicable to this invention can be represented by Equation 8:

[0104] Formula 8

[0105] The PLA suitable for use in this invention can be produced from one or both of the D-isomer or L-isomer of lactic acid or lactide monomers. For economic reasons, the PLA preferred in this invention is mainly the L-isomer. The PLA preferred in this invention is >80% L-isomer, more preferably >90% L-isomer, and most preferably >95% L-isomer.

[0106] The melt flow rate (ASTM D 1238, 210°C, 2.16 kg) of the preferred PLA used in this invention is 0.1-150 g / 10 min. The MFR of the preferred PLA that can be used as the polyester of this invention is 0.5-100, for example 0.5-80, for example 1-50, for example 0.5-15.

[0107] Examples of PLAs that can be used in this invention include Ingeo Biopolymer 3001D, 3051D, 3052D, 4043D, 4044D, 6302D, and 6060D (Natureworks, Plymouth, MN USA) and Luminy L175, LX175, LX530, LX930, and LX975 (TotalEnergies Corbion, Gorinchem, Netherlands).

[0108] In some embodiments where the polyester is PLA, the PLA contains a minimal amount of crosslinking or branching to provide an increase in viscosity, shear thinning, or elasticity. Branching can be achieved by adding a chain extender containing reactive functional groups (e.g., glycidyl methacrylate (“GMA”)) or by radical-mediated coupling (e.g., via peroxides). The chain extender can be incorporated into the PPA in any manner known in the art. The chain extender can be extruded with the PLA in a first extrusion step to provide an increase in the PLA’s viscosity, shear thinning, or elasticity. The resulting branched PLA can then be incorporated into the PPA composition of the present invention in a second step. Alternatively, the chain extender can be incorporated into the PPA composition of the present invention in a single step. Examples of chain extenders of the present invention include Joncryl 4400 and Joncryl 4468 (BASF, Ludwigshafen, Germany). Branching can also be achieved via radical-mediated chemistry, including by using organic peroxides or ultraviolet radiation. Branching via free radical-mediated chemistry can be completed in the first step to produce branched PLA prior to incorporation into the masterbatch or extrudable composition.

[0109] The poly(glycolic acid) suitable for use in this invention can be represented by Formula 9:

[0110] Formula 9

[0111] The preferred MFR of the PGA suitable for use in this invention is 0.5-50 (2.16 kg, 250°C). A more preferred MFR of the PGA suitable for use in this invention is 1-40, and even more preferably 5-30. Examples of PGAs suitable for use in this invention include Kuredux (Kureha, Japan).

[0112] The poly(caprolactone) suitable for use in this invention can be represented by Formula 10:

[0113] Formula 10

[0114] The preferred PCL suitable for use in this invention has a molecular weight greater than 1000 g / mol. More preferably, the PCL suitable for use in this invention has a molecular weight greater than 2000 g / mol, for example greater than 3000 g / mol, greater than 10000 g / mol, or greater than 40000 g / mol. Examples of PCLs that can be used as polyesters in this invention include Capa 2403D, Capa 6500, and Capa 6800 (Ingevity, North Charleston, USA).

[0115] Polyesters and ester copolymers that can be used in this invention include polyhydroxyalkanoates. PHAs suitable for use in this invention include poly(4-hydroxybutyrate) (“P4HB”) represented by Formula 11, poly(3-hydroxyvalerate) (“PHV”) represented by Formula 12, poly(3-hydroxybutyrate) (“P3HB”) represented by Formula 13, and copolymers thereof, including poly(3-hydroxybutyrate-co-4-hydroxybutyrate) represented by Formula 14 and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) represented by Formula 15.

[0116] Formula 11

[0117] Formula 12

[0118] Formula 13

[0119] Formula 14

[0120] Formula 15

[0121] The PHAs that can be used in this invention include PHACT A 1000P (CJ Biomaterials, Indonesia).

[0122] Other aliphatic ester copolymers that can be used as PPA components of the present invention include alkylene glycol-dicarboxylic acid copolymers represented by Formula 16.

[0123] Formula 16

[0124] Where R 6 and R 7 They may be the same or different, and are alkyl chains with 2-12 carbon atoms.

[0125] Examples of such alkylene glycol-dicarboxylic acid copolymers include polyadipate copolymers comprising poly(ethylene glycol adipate), poly(propylene glycol adipate), and poly(butylene adipate). Other examples of alkylene glycol-dicarboxylic acid copolymers include polysuccinate copolymers comprising poly(ethylene glycol succinate), poly(propylene glycol succinate), poly(butylene succinate) (“PBS”), and poly(cobutylene succinate) (“PBSA”). PBS used as polyesters in this invention includes BioPBS FZ 91 and BioPBS FZ 71PM (PTT MCC Biochem, Thailand) and BG 5000M (An PhatHolding, Vietnam). PBSA used as ester copolymers in this invention includes BioPBS FD 72PM and BioPBS FD 92PM (PTT MCC Biochem, Thailand).

[0126] Aromatic polyesters and aromatic ester copolymers suitable for use in this invention include poly(ethylene terephthalate) (“PET”), poly(butylene terephthalate) (“PBAT”), poly(butylene succinate-co-butylene terephthalate) (“PBST”), and poly(butylene terephthalate-co-alkylene oxide). PBAT, which can be used as an ester copolymer in this invention, includes BG 1000 and BG 1070 (An Phat Holding, Vietnam). Poly(butylene terephthalate-co-alkylene oxide) that can be used as an ester copolymer in this invention includes Hytrel 3078FG, Hytrel 4053FG NC010, Hytrel 4068FG, Hytrel 5553FG NC010, and Hytrel 6359FG NC010.

[0127] The processing aids particularly preferred by the present invention include PVAc with a Mw of 300,000-500,000 g / mol, and a combination of PVAc and PLA with a Mw of 300,000-500,000 g / mol in a PVAc:PLA weight ratio of 3:1.

[0128] Preferred processing aids of the present invention also include PVAc with a Mw greater than about 50,000 g / mol, a combination of PVAc with a Mw greater than about 50,000 g / mol and PLA in a 3:1 weight ratio of PVAc:PLA, and a combination of PEVA with a vinyl acetate content of 75-95% and PLA in a 3:1 weight ratio of PEVA:PLA. Such products can be used as polymer processing aids, in polyethylene at 0.0250-0.3% by weight in extrudable compositions and at 3%-45% as masterbatches.

[0129] Synergist

[0130] The compositions of the present invention optionally contain a synergist. The synergist of the present invention is one or both of poly(alkylene oxide) (also known as poly(epoxyalkane)) or polymeric liquid phosphite antioxidants.

[0131] In one embodiment of the invention, the poly(alkylene oxide) is polyethylene glycol. In a preferred embodiment of the invention, the polyethylene glycol has a molecular weight of 1000-20000 g / mol. In a more preferred embodiment of the invention, the polyethylene glycol has a molecular weight of 2000-10000 g / mol. An example of polyethylene glycol that can be used in the present invention is DowCarbowax 8000.

[0132] In another embodiment of the invention, the synergist is a polymeric liquid phosphite antioxidant. U.S. Patent Nos. 8,563,637 and 8,981,042 disclose polymeric liquid polyphosphites that can be used in this invention. Examples of polymeric liquid phosphites that can be used in this invention are Dover Chemical Corp (Dover, OH) Doverphos LGP-11 and Doverphos LGP-12.

[0133] Boron nitride

[0134] Boron nitride can be present in the extrudable composition at an amount of 0.005-0.2%. Boron nitride can be present in the masterbatch composition at a higher concentration of 0.2-10% by weight. Boron nitride preferably has an average particle size of less than 30 micrometers. Boron nitride preferably has an average particle size of less than 10 micrometers. An example of boron nitride that can be used in this invention is Saint-Gobain CarboTherm PCTF5. Boron nitride can be used in combination with the above-mentioned synergists.

[0135] Other polymer additives

[0136] The compositions of the present invention may also contain other polymer additives known in the art. Other polymer additives that may be added to the compositions of the present invention include, but are not limited to, hindered phenolic and phosphite antioxidants, catalysts / acid neutralizers (including hydrotalcite, zinc oxide), and metal carboxylates (including calcium stearate, zinc stearate, potassium stearate, magnesium stearate, lithium stearate, and sodium stearate). Other polymer additives that may be included in the compositions of the present invention include slip agents, anti-blocking additives, antistatic agents, ultraviolet A (UVA) absorbers, and hindered amine light stabilizers (HALS).

[0137] Hindered phenols are known as antioxidants for polyolefins. Hindered phenols particularly suitable for use in this invention include, but are not limited to:

[0138] Octadecyl-(3-(3,5-di-tert-butyl-4-hydroxyphenol)propionate) (“AO 1076”; CAS No. 2082-79-3),

[0139] Pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenol)propionate) (“AO 1010”; CAS No. 6683-19-8),

[0140] 1,3,5-Tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (“AO 1790”; CAS No. 40601-76-1),

[0141] 1,3,5-Tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1h, 3h, 5h)-trione (“AO3114”; CAS No. 27676-62-6), and

[0142] 1,3,5-Trimethyl-2,4,6-Tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (“AO 1330”, CAS No. 1709-70-2).

[0143] Phosphites and phosphonites are also known as antioxidants for plastics. They are primarily aromatic phosphites and phosphonites. Phosphites and phosphonites that can be used in this invention include, but are not limited to:

[0144] Tris-(2,4-di-tert-butylphenyl)phosphite (“AO 168”, CAS No. 31570-04-4),

[0145] Bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphate (“AO 626”, CAS No. 26741-53-7),

[0146] Tetra(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4′-dimethylbisphosphonate (“AO PEPQ”, CAS No. 38613-77-3),

[0147] Bis(2,4-di-tert-cumylphenyl)pentaerythritol diphosphate (“AO 9228”, CAS 154862-43-8), and

[0148] Phosphorous acid, a mixture of 2,4-bis(1,1-dimethylpropyl)phenyl and 4-(1,1-dimethylpropyl)phenyl triesters; (“AO 705”, CAS939402-02-5).

[0149] The metal carboxylates that can be used in this invention include metal stearates, including calcium stearate, zinc stearate, magnesium stearate, and lithium stearate.

[0150] The slip agents that can be used in this invention include erucamide (CAS No. 112-84-5) and oleamide (CAS No. 301-02-0).

[0151] The anti-adhesion additives that can be used in this invention include synthetic silica (CAS No. 112926-00-8), diatomite (CAS No. 68855-54-9), nepheline syenite (CAS No. 37244-96-5), talc (CAS No. 14807-96-6), hydrated sodium calcium aluminosilicate (CAS No. 1344-01-0), and calcined kaolin (CAS No. 92704-41-1).

[0152] The antistatic additives that can be used in this invention include glyceryl monostearate (CAS No. 31566-31-1).

[0153] The UVA that can be used in this invention includes 2-hydroxy-4-(octyloxy)benzophenone (“UVA81”; CAS No. 1843-05-6), and

[0154] 2-(4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-(octoxy)-phenol (“UVA1164”, CAS No. 2725-22-6).

[0155] The HALS that can be used in this invention includes 1,3,5-triazine-2,4,6-triamine, N,N”'-[1,2-ethylenedimethylbis[[[4,6-bis-[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]]bis[N',N”-bis91,2,2,6,6-pentamethyl-4-piperidinyl)-(“HALS119”; CAS No. 106990-43-6),

[0156] Poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]] (“HALS 944”; CAS No. 71878-19-8),

[0157] Polymers of 1,6-hexanediamine, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)- and 2,4,6-trichloro-1,3,5-triazine, and reaction products with N-butyl-1-butylamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinylamine (“HALS 2020”; CAS No. 192268-64-7);

[0158] Poly[(6-morpholino-s-triazine-2,4-diyl)[2,2,6,6-tetramethyl-4-piperidinyl)imino]-hexamethylene[(2,2,6,6-tetramethyl-4-piperidinyl)imino]] (“HALS 3346”; CAS No. 82451-48-7),

[0159] 1,6-Hexamethylenediamine, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-and morpholino-2,4,6-trichloro-1,3,5-triazine polymer (“HALS 3529”, CAS No. 193098-40-7) and

[0160] Polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (“HALS622”, CAS No. 65447-77-0).

[0161] theory

[0162] Poly(vinyl esters) (including PVAc) are used in industry for a variety of purposes, including as a binder in coatings and films, and as a component of hot melt adhesives. Surprisingly, low concentrations of 0.01–1.0% poly(vinyl esters) or vinyl ester copolymers have been found to be useful as polymer processing aids for polyolefins.

[0163] Without being bound by theory, it is believed that the poly(vinyl ester) or vinyl ester copolymer polymer processing aid of the present invention functions similarly to the prior art fluoropolymer PPA. That is, the polymer processing aid coats the extrusion die wall, particularly the die exit, and induces a certain sliding speed between the PPA coating and the polyolefin being processed. It is believed that the poly(vinyl ester) or vinyl ester copolymer-based PPA of the present invention effectively achieves this.

[0164] It is believed that specific poly(vinyl ester) or vinyl ester copolymers can be used as PPAs. More preferred selections of poly(vinyl ester) or vinyl ester copolymers suitable for use as PPAs can be made by selecting specific poly(vinyl ester) or vinyl ester copolymers having a specific range of physical and chemical properties. Following the teachings of fluoropolymer processing aids, the PPA based on the poly(vinyl ester) or vinyl ester copolymer should be immiscible with polyolefins, should be able to adhere to the metal or metal oxide of the extrusion die, should readily spread on the metal extrusion die and form a coating to form a sliding layer, should have low adhesion work with polyolefins to promote sliding, and should possess sufficient thermal and chemical stability.

[0165] For application in large-volume food packaging, the PPA should preferably be non-migratory, suitable for food contact, and have no significant negative impact on the film's haze or transparency.

[0166] The PPAs applicable to this invention are based on poly(vinyl ester) or vinyl ester copolymers. It is believed that ester functional groups promote bonding with the metal oxide surface of the extrusion die. As a non-limiting example, poly(vinyl acetate) and vinyl acetate copolymers are believed to have high affinity for the die wall. In the case of poly(ethylene-co-vinyl acetate) copolymers, a higher vinyl acetate content is believed to provide better bonding with the extrusion die and reduce miscibility with the polyolefin matrix.

[0167] It is believed that the poly(vinyl ester) or vinyl ester copolymer should also be selected based on its interfacial tension with the polyolefin. It is believed that the PPA functions by promoting sliding between the PPA layer on the die and the polyolefin. The critical shear rate at which sliding begins is related to the adhesion work between the polyolefin and the PPA. It is believed that the PPA based on the poly(vinyl ester) or vinyl ester copolymer of the present invention has suitable properties for promoting interfacial sliding between the polyolefin and the PPA layer.

[0168] It is believed that the coating efficiency of the poly(vinyl ester) or vinyl ester copolymer-based PPAs applicable to the present invention is a function of the molecular weight, molecular weight distribution, and structure of the polyester, which affects its viscosity, shear thinning properties, and elasticity. It is believed that the viscosity of the poly(vinyl ester) or vinyl ester copolymer should be similar to the viscosity of the polyolefin at the processing temperature and shear rate range. The poly(vinyl ester) or vinyl ester copolymer should preferably be dispersed in the polyolefin at the extrusion die with an average particle size of 0.2-30 micrometers, more preferably 0.5-20 micrometers, still more preferably 1-15 micrometers, and most preferably 1-10 micrometers, to promote effective coating of the die wall. This particle size is achieved by selecting poly(vinyl ester) or vinyl ester copolymers with suitable rheological properties, by adding polyesters or synergists, combinations thereof, and by combining processing conditions.

[0169] Therefore, the selection of a specific poly(vinyl ester) or vinyl ester copolymer can depend on many factors. The molecular weight, molecular weight distribution, structure, and surface energy of the poly(vinyl ester) will affect the coating kinetics of PVAc on the die head. The poly(vinyl ester) or vinyl ester copolymer will have an adhesion work and characteristic interfacial tension with the polyolefin of the composition of the present invention. The poly(vinyl ester) or vinyl ester copolymer will preferably have a low adhesion work with the polyolefin to facilitate the sliding of the polyolefin on the PVAc-based PPA coated on the die head wall.

[0170] The poly(vinyl ester) or vinyl ester copolymer should have a sufficient molecular weight to give it good thermal stability and to be non-migrating in the final polyolefin product.

[0171] It is believed that, depending on the specific combination of components, a combination of polyester with poly(vinyl ester) or vinyl ester copolymers can be used to improve the performance of PPAs. The mechanism behind this improvement is not yet understood.

[0172] In addition, or as a substitute for polyester, synergists can improve the performance of PPAs. The synergists can also act as surfactants to reduce shear on the poly(vinyl ester) or vinyl ester copolymer, thereby maintaining sufficient average particle size. To provide this function, the viscosity of the synergist under processing conditions should be lower than the viscosity of the poly(vinyl ester) or vinyl ester copolymer. Polyethylene glycol, which can be used in this invention, can perform this function. It is also known that PEG independently acts to reduce extrusion defects, such as sharkskin melt fracture and die line. Although the polymeric liquid phosphites of this invention are also considered to act as synergists to improve the performance of PPAs, they are believed to provide additional benefits, namely, that they mitigate the degradation of the polymer. It is anticipated that reduced degradation of polyolefins will decrease the frequency of crosslinking gelation and reduce the oxidation of the polymer on the metal surfaces of the processing equipment.

[0173] Extrudable compositions and masterbatches

[0174] The extrudable compositions of the present invention can be used in polyolefin extrusion processes (including blown film, cast film, sheet extrusion, extrusion blow molding, fiber spinning, and profile extrusion) to reduce or eliminate melt fracture (including the previously described sharkskin effect). Based on the total weight of the polyolefin composition, a minimum of 0.01-1.0% by weight of PPA is required in the extrudable polyolefin composition to reduce or delay melt fracture. Suitably, based on the total weight of the polyolefin composition, the extrudable composition contains 0.01-1.0% by weight of PPA, a suitable amount is 0.01-0.7% by weight, a preferred amount is 0.02-0.5% by weight, and a more preferred amount is 0.02-0.2% by weight.

[0175] In some applications of the present invention, the PPA composition includes, in addition to poly(vinyl ester) or vinyl ester copolymer, polyester or polyester copolymer. The polyester or ester copolymer is used with the poly(vinyl ester) or vinyl ester copolymer in a weight ratio of 1:10 to 10:1, preferably 1:3 to 10:1, more preferably 1:1 to 8:1, and most preferably 1:1 to 5:1. When the PPA comprises polyester or ester copolymer, the combination of poly(vinyl ester) or vinyl ester copolymer and polyester or ester copolymer is used at a concentration as low as 0.01-1.0% by weight of the extrudable polyolefin composition to reduce or delay melt fracture. Suitably, the extrudable composition contains 0.01-0.7% PPA, for example 0.02-0.5%, or 0.02-0.2%.

[0176] In some applications of the present invention, the PPA includes a synergist. The synergist is used with the poly(vinyl ester) or vinyl ester copolymer at a ratio of 1:10 to 10:1, preferably 1:5 to 5:1, and more preferably 1:3 to 3:1. When the PPA includes a synergist, the combination of the poly(vinyl ester) or vinyl ester copolymer, polyester or polyester copolymer (if present), and the synergist is used at a concentration as low as 0.01-1.0% by weight of the extrudable polyolefin composition to reduce or delay melt fracture. Preferred extrudable compositions contain 0.01-0.7% of this combination, for example, 0.02-0.5% or 0.02-0.2%.

[0177] In some applications of the present invention, the PPA comprises boron nitride. The boron nitride is present in the extrudable composition in an amount of 0.005-0.2%. The boron nitride preferably has an average particle size of less than 30 micrometers. More preferably, the boron nitride has an average particle size of less than 10 micrometers. When the PPA comprises boron nitride, the combination of the poly(vinyl ester) or vinyl ester copolymer, polyester or polyester copolymer (if present), synergist (if present), and boron nitride is used at a concentration as low as 0.01-1.0% by weight of the extrudable polyolefin composition to reduce or delay melt fracture. Preferably, the extrudable composition contains 0.01-0.7% of this combination, for example, 0.02-0.5% or 0.02-0.2%.

[0178] The extrudable compositions of the present invention can be prepared by a polyolefin producer in a post-reactor granulation operation. Granulation is typically achieved by die extrusion via a twin-screw extruder, melt pump, or similar apparatus known in the art. Numerous techniques can be used to introduce the PPA component, along with other polymer additives known in the art, into the post-reactor polyolefin stream. The PPA can be directly fed into the polyolefin stream, where it is mixed into the polymer prior to granulation. Systems for storing, handling, and dispensing the PPA are well known in the art. However, in some post-reactor granulation operations, the desired feed system may not be available, or it may be desirable to process and feed the PPA and optional additional additives via a masterbatch. This can be achieved by preparing a masterbatch in a polyolefin carrier polymer with a higher concentration of PPA and optional additional additives.

[0179] The use of masterbatches is well known in the art. Producing masterbatches that yield a higher concentration of PPA component to be added to a base polymer to achieve the final extrudable composition improves the accuracy of formulating that extrudable composition. The use of masterbatches also allows for the formulation of PPA in combination with other polymer additives via a single masterbatch.

[0180] The compositions of the present invention, which can be used as polyolefin masterbatches, contain 1-45% by weight of PPA based on poly(vinyl ester) or vinyl ester copolymers in the polyolefin carrier polymer. In some embodiments, the masterbatch contains 1.5-40% PPA in the polyolefin carrier polymer. Preferred compositions, which can be used as masterbatches, contain 2-30% PPA, for example 2%-25%, for example 2-10%.

[0181] The polyolefin carrier polymer used in the masterbatch composition of the present invention is compatible with the base polymer (in which the masterbatch will be placed). Preferably, the polyolefin carrier polymer used in the masterbatch composition is miscible with the base polymer. For example, a polyethylene carrier is a preferred carrier polymer of the masterbatch of the present invention for modifying a polyethylene base polymer. If the base polymer is LLDPE, the polyethylene carrier polymer of the masterbatch is preferably polyethylene, and more preferably LLDPE.

[0182] Using the masterbatch compositions of the present invention allows polyolefin manufacturers to accurately prepare the extrudable compositions of the present invention, thereby selling fully formulated polyolefins with good processing properties to downstream converters. The polyolefin manufacturer may include other polymer additives in its fully formulated polyolefins. Other polymer additives that may be included by the polyolefin manufacturer include hindered phenolic and phosphite antioxidants, catalysts / acid neutralizers (including hydrotalcite, zinc oxide), and metal carboxylates (including calcium stearate, zinc stearate, potassium stearate, magnesium stearate, lithium stearate, and sodium stearate). Other polymer additives that may be included are slip agents, anti-blocking additives, and antistatic agents. These polymer additives may optionally be included in the PPA masterbatch compositions of the present invention. Including these additives in the masterbatch, in addition to the PPA of the present invention, simplifies or improves the handling and feeding of various additives into the polyolefin.

[0183] In some cases, downstream converters (such as membrane manufacturers) may not want to purchase fully formulated polyolefins. Using PPA masterbatches allows converters to customize the composition of the base polymer to meet the specific needs of their conversion processes. The masterbatch allows converters to adjust the activity level of PPA in the extrudable compositions of this invention to meet the specific requirements of individual processing units and products. The use of masterbatches also allows converters to use higher levels of PPA to "shock" their systems for shorter periods, reducing the settling time required to remove sharkskin melt fracture.

[0184] Therefore, the use of masterbatches with higher concentrations of PPA and optional additional additives in the polyolefin compositions of the present invention is useful to both polyolefin producers and downstream converters.

[0185] The compositions of this invention differ from those of the prior art in that they are substantially fluorine-free and remove, reduce, or delay the onset of sharkskin. The compositions of this invention can provide additional benefits in polyolefin extrusion, including reduced extrusion pressure, increased output, and reduced die lip buildup.

[0186] Example

[0187] The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0188] Table 1: List of Materials

[0189] *Vinnex melt volumetric rate (MVR) and molecular weight (Mw) data are taken from "Vinnex". ® -Enabling theNext Generation of Bioplastics”, Wacker (Germany), https: / / www.wacker.com / h / medias / 7002-EN.pdf.

[0190] **Data is from Arlanxeo product data sheets.

[0191] The list of materials used in the control, comparative examples and embodiments of the present invention is provided in Table 1.

[0192] To improve the accuracy of PPA dosing, masterbatches were prepared according to the formulations in Table 2. LLDPE 2 (LyondellBasell Petrothene GA 502024), received in granular form, was ground to a top size of 12 mesh and used as the carrier polymer for all masterbatches. 6 kg batches of each formulation were weighed in portions to two decimal places on a digital balance. For additives present in amounts less than 0.5 kg, the mass was measured in grams to two decimal places on the digital balance. If all additives were solids, the weighed batches were tumbled and mixed for 2 minutes; if liquid components were present in the formulation, they were mixed at high speed for 5 minutes.

[0193] The masterbatch formulation from Table 2 was fed into a Coperion ZSK 30 co-rotating twin-screw extruder via a weight loss feeder; it is equipped with a 30mm diameter, 36 length / diameter (L / D) screw assembly. A low-shear screw design was used. The ZSK30 extruder is equipped with 6 barrel sections. The temperature of the final barrel section, from the feed section to the die, is set at 110-140-160-170-180-180°C. The extruder is equipped with an Econ EWA 50 granulator for underwater granulation. The diverter valve temperature and the die temperature are set at 170°C. All masterbatch was extruded at a rate of approximately 18.3 kg / hr at 350 rpm.

[0194] Table 2: Masterbatch Formulation

[0195] The time to eliminate surface melt fracture in blown film extrusion (“removal time”) was evaluated on a Lung Meng AH-42 blown film production line equipped with a 42mm single-screw extruder (L / D=24:1), a 68.58mm diameter die (die clearance of 0.508mm), and external bubble cooling. Exxon Mobil LL1001 X31 (LLDPE1) was used as a control polymer and as the base polymer for all comparative examples and embodiments of the present invention. 100% concentration LLDPE1 was extruded at a temperature profile of 150–180–185–185°C, with a die temperature of 185°C, a screw speed of 32 RPM, and a rate of 9 kg / h, corresponding to 350 s. -1 The apparent shear rate. The shear rate is calculated using the following formula:

[0196] γ w，a =6Q / (πD b 2 )

[0197] Where γ w，a is the apparent wall shear rate, Q is the volumetric flow rate, D is the average of the inner and outer diameters of the die, and b is the die clearance. The melt density of LLDPE1 is taken as 770 kg / m³. 3 .

[0198] Under these conditions, LLDPE1 was found to exhibit sharkskin melt fracture (i.e., 100% melt fracture) around the entire circumference of the membrane.

[0199] According to the formulations in Table 3, the PPA masterbatch from Table 2 was dry-blended with LLDPE 1 granules to produce an extrudable composition. The hopper of the film production line extruder was run empty, and then immediately loaded with the formulations to be evaluated from Table 3, while simultaneously starting a timer. The pressure before the extrusion die was measured via a pressure sensor located on the adapter between the single-screw extruder and the blown film die. The die pressure was measured at 10-minute intervals, and film samples were collected for 1 minute, with the production rate recorded in lbs / hour. The film was laid flat on a light table for visual observation of areas containing sharkskin melt fractures. The melt fractures were removed in the form of strips parallel to the processing direction. The widths of the films exhibiting melt fractures were marked and measured. The sum of the widths of the sharkskin-containing areas divided by the total width of the film provides the melt fracture percentage. In some cases, the melt fractures exhibited a gradually decreasing intensity before being eliminated. Such areas of decreasing melt fracture intensity are still considered and measured as melt fractures.

[0200] After each evaluation of one of the compositions in Table 3, 15 kg of 50% calcined diatomaceous earth masterbatch (Ingenia Polymers IP 1052) was run through the membrane production line to flush the PPA from the metal surfaces of the die and extruder. Following this purging, LLDPE1 was run through the membrane production line for 1 hour to remove any remaining diatomaceous earth (DE) and to re-establish 100% melt fracture before the next evaluation.

[0201] The results for the control (C), comparative examples (CE1), and embodiments of the present invention (E1-E15) are shown in Table 3. The clearance time results are also plotted in... Figures 1-7 middle.

[0202] Table 3. Results of comparative and example formulations and clearance time studies.

[0203] Discussion of experimental results

[0204] Refer to Table 3 and Figure 1 As observed, Comparative Example CE1 demonstrates the excellent performance of conventional polymer processing aids composed of fluoropolymers and polyethylene glycol in removing sharkskin from LLDPE. CE1 shows that a composition of 600 ppm FKM1 in LLDPE1 prepared via the masterbatch route (masterbatch CMB) can remove 100% of melt fracture within 1 hour under the test conditions. Furthermore, compared to the control, the output increased by 26% under the same extruder conditions (RPM), and the die pressure decreased by 23%.

[0205] PVAc1 is a homopolymer of PVAc with an MVR of 26 cm⁻¹. 3 / 10min (10°C, 21.6kg) and Mw is 65000 g / mol. Example E1 shows that an extrudable composition of 2000 ppm PVAc1 in LLDPE1 completely eliminates melt fracture within 1 hour. Figure 1 Composition E1 (2000 ppm PVAC1) showed that it eliminated melt fracture at a rate comparable to CE1 (600 ppm FKM1). The extrudable composition E1 also showed a 20% decrease in extrusion pressure, but a 6% decrease in output at a constant extruder RPM. CE1 (FKM1) showed a 26% increase in output.

[0206] PVAc2 is a homopolymer of PVAc with an MVR of 15.4 cm⁻¹. 3 / 10min (150°C, 21.6kg), and Mw of 330,000-430,000 g / mol. Example E2 shows that the extrudable composition of 2000 ppm PVAc2 in LLDPE1 completely eliminated melt fracture within 1 hour. Figure 1 Composition E2 (2000 ppm PVAC2) showed that it eliminated melt fracture at a faster rate than CE1 (600 ppm FKM1). The extrudable composition E2 also showed a 17% reduction in extrusion pressure and a 3% increase in output at a constant extruder RPM.

[0207] The comparison of Examples E1-E2 shows that the molecular weight of PVAc, which affects the viscosity and elasticity of PVAc, influences its performance as a PPA.

[0208] The extrudable compositions E3, E4, and E5 used PVAc2 loadings of 1000, 500, and 250 ppm as PPA, respectively. The results for E3-E5 can be compared with those for E2 to examine the effect of PVAc concentration in the extrudable compositions. Refer to Table 3 and... Figure 2 It can be seen that reducing the PVAc2 loading has a progressively but slightly negative impact on the scavenging time performance of the composition. However, at all loadings from 250 ppm to 2000 ppm, PVAc2 completely scavenged melt fracture within 60 minutes. Furthermore, reducing the PVAc2 loading showed a progressively positive effect on extruder output at a constant RPM. As the PVAc2 loading decreased from 2000 ppm to 250 ppm, the output relative to the control increased from 3% to 9%. The scavenging time performance of PVAc2 is highly advantageous compared to the conventional fluoroelastomer FKM1 at 600 ppm.

[0209] The extrudable composition E6 was used to study the effect of the combination of PLA1 and PVAc2 in PPA compositions. (Reference) Figure 3 As can be seen from Examples E6 and Table 3, the extrudable composition of LLDPE1 with 750 ppm PVAc2 and 250 ppm PLA1 completely eliminated melt fracture within 1 hour. Figure 3Composition E6 was shown to clear melt fracture at a faster rate than the conventional fluoroelastomer composition CE1 (600 ppm FKM1). The extrudable composition E6 also showed a 21% increase in output at a constant extruder RPM. These values ​​are comparable to the rate increase and pressure drop seen in CE1. However, it can be seen that the clearing time performance is not as favorable as in Example E3, which has the same 1000 ppm PPA loading containing only PVAc2 and no PLA1. This indicates that the partial replacement of PVAc2 with PLA1 in the PPA composition reduces the clearing time performance but improves the specific output of the extruder for the LLDPE1-based extrudable composition.

[0210] PEVA4, PEVA5, PEVA6, PEVA8, and PEVA9 are poly(ethylene-co-vinyl acetate) copolymers containing 40, 50, 60, 80, and 90 wt% vinyl acetate comonomers, respectively. Details of the density and Mooney viscosity of these materials are shown in Table 3. PEVA4, PEVA5, PEVA6, PEVA8, and PEVA9 were used to prepare extrudable compositions E7, E8, E9, E10, and E11, respectively. E7, E8, E9, E10, and E11 contain 1000 ppm of PEVA, which contains 50, 60, 80, and 90 wt% vinyl acetate comonomers, respectively. Reference Figure 4Several observations can be made, as shown in Table 3. E7, containing 1000 ppm PEVA4 (40% VAc), showed no reduction in melt fracture during the 60-minute extrusion time. This 40% VAc copolymer did not exhibit any PPA properties in the resin at a 1000 ppm loading and under the test conditions. E8, containing 1000 ppm PEVA5 (50% VAc), showed a modest reduction in melt fracture to 78.5% of the film surface after 60 minutes. The extrudable composition E9, containing 1000 ppm PEVA6 (60% VAc), showed improved performance; melt fracture decreased to 20% at 60 minutes. The extrudable composition E10, containing 1000 ppm of the 80% VAc copolymer PEVA8, almost completely eliminated melt fracture within 60 minutes, leaving only 2.8% of the sharkskin. The clearance time curve closely matched that of CE1, containing 600 ppm of a conventional fluoropolymer processing aid. Furthermore, composition E10 resulted in a 27% increase in extruder specific output and a 9% decrease in die pressure. The extrudable composition E11, containing 1000 ppm PEVA9 (90% VAc), completely eliminated melt fracture within 60 minutes. The clearance time curve of E11 closely matched that of E3, which contained PVAc homopolymer. However, E11 showed a greater increase in extruder specific output (+33% vs. +6%) and a significant decrease in die pressure. This increase in specific output was even greater than that observed with fluoropolymer PPAs. In summary, the data from E7, E8, E9, E10, E11, and E3 indicate that the PEVA-based PPAs of the present invention require a certain minimum VAc content to be effective. The data also show that the performance of PEVA-based PPAs improves with higher VAc contents. The clearance time performance of PEVA8 (80% VAc) at 1000 ppm is comparable to that of fluoropolymer-based PPAs at 600 ppm. PEVA9 (90% VAc) exhibits scavenging time performance equivalent to PVAc homopolymers and offers the benefit of improved specific output. Although no discoloration (yellowing) was observed in these studies, when PVAc does degrade, it occurs via an autocatalytic mechanism (Rimez et al., The thermal degradation of poly(vinyl acetate) and poly(ethylene-co-vinyl acetate), Part I: Experimental study of the degradation mechanism, Polymer Degradation and Stability 93 (2008) 800-810). This mechanism can be hindered by the presence of ethylene in PEVA.Therefore, for applications involving high temperature or high shear, PEVA with a high VAc content is superior to PVAc.

[0211] E10, containing 1000 ppm PEVA8 (80% VAc), exhibited some residual melt fracture after a 60-minute extrusion time. An extrudable composition E12, containing 1500 ppm PEVA8, was prepared for comparison. Reference Figure 5 As shown in Table 3, increasing the PEVA-based PPA from 1000 ppm to 1500 ppm resulted in a significant improvement in the melt fracture clearance time. Melt fracture was completely cleared within 40 minutes. A 24% increase in output and an 11% reduction in die pressure were also recorded. This indicates that while PEVA8 is not as effective as PEVA9 (90% VAc), it can still provide good performance by increasing the PPA loading. 80% VAc content in PVAc is converted to approximately 56.6 mol% VAc. For this random PEVA8 copolymer, the average length of the continuous VAc units will be shorter than in PEVA9, and therefore the color of PEVA8 should be better than that of PEVA9 when subjected to degradation conditions.

[0212] The performance of extrudable composition E13 containing 750 ppm PEVA8 and 250 ppm PLA1 is shown to be... Figure 6 As shown in Table 3, E13 exhibited 0% melt fracture after 60 minutes, a 33% increase in specific output of the extrusion line, and a 12% reduction in die pressure. E13 outperformed the fluoropolymer-based PPA in CE1 at 600 ppm in terms of clearance time and showed a greater increase in specific output of the extruder. The combination of 750 ppm PEVA8 with 250 ppm PLA1 also outperformed 1000 ppm PEVA8 alone (E10). Replacing a certain percentage of PEVA8 with PLA improved the clearance time performance of the PPA. It also moderately increased the specific output and showed a better reduction in die pressure. The performance of E13 can also be compared with E6 containing 750 ppm PVAC2 and 250 ppm PLA1. The clearance time performance of E13 and E6 is comparable. Replacing PVAc in E6 with PEVA8, as in E13, did not reduce clearance time performance. This can be compared to the relatively better performance of 1000 ppm PVAc in E3 compared to 1000 ppm PEVA8 in E10. When PEVA8 and PLA1 are used together in a 3:1 ratio, PLA1 is a very effective co-additive for PEVA8 in the PPA of this invention.

[0213] The performance of extrudable composition E14 containing 1500 ppm PVAc2 and 500 ppm PLA1 is shown to be...Figure 7 As shown in Table 3, and can be compared with extrudable composition E15 containing 1500 ppm PVAc2 and 500 ppm PEG8000. E14 showed 0% melt fracture remaining after 60 minutes, increasing the specific output of the extrusion line by 15%. E15 failed to eliminate sharkskin at 60 minutes and showed a decrease in the specific output of the extruder. Comparing E14 and E15 shows that PLA is a more effective PVAc co-additive than PEG8000. Claims (as amended under Article 19 of the Treaty) 1. A method for reducing or eliminating melt fracture or die lip buildup in an extrudable polyolefin extrusion process, comprising: using a poly(vinyl ester) or vinyl ester copolymer as a polymer processing aid during extrusion, wherein the amount of said polymer processing aid is 0.01-1.0% by weight, based on the total weight of the polyolefin composition, provided that when said poly(vinyl ester) or vinyl ester copolymer is poly(ethylene-co-vinyl acetate), said vinyl acetate content is greater than 60% by weight, and said polymer processing aid is substantially free of perfluoroalkyl and polyfluoroalkyl substances (PFAS). 2. Use of a poly(vinyl ester) or vinyl ester copolymer as a polymer processing aid to reduce or eliminate melt fracture or die lip buildup in an extrudable polyolefin composition, wherein the amount of said polymer processing aid is 0.01-1.0% by weight, based on the total weight of said polyolefin composition, provided that when said poly(vinyl ester) or vinyl ester copolymer is poly(ethylene-co-vinyl acetate), said vinyl acetate content is greater than 60% by weight, and said polymer processing aid is substantially free of perfluoroalkyl and polyfluoroalkyl substances (PFAS). 3. An extrudable composition comprising a polyolefin and a polymer processing aid, said polymer processing aid being present in an amount of 0.01-1.0% by weight based on the total weight of the polyolefin composition, and said polymer processing aid comprising a poly(vinyl ester) or a vinyl ester copolymer, provided that when said poly(vinyl ester) or the vinyl ester copolymer is poly(ethylene-co-vinyl acetate), said vinyl acetate content is greater than 60% by weight, and said polymer processing aid is substantially free of perfluoroalkyl and polyfluoroalkyl substances (PFAS). 4. A masterbatch composition comprising a polyolefin and a polymer processing aid, said polymer processing aid being present in an amount of 1-45% by weight based on the total weight of the polyolefin composition, and said polymer processing aid comprising a poly(vinyl ester) or a vinyl ester copolymer, provided that when said poly(vinyl ester) or vinyl ester copolymer is poly(ethylene-co-vinyl acetate), said vinyl acetate content is greater than 60% by weight, and said masterbatch is substantially free of perfluoroalkyl and polyfluoroalkyl substances (PFAS). 5. The use, method, or composition according to any one of the preceding claims, wherein the poly(vinyl ester) or vinyl ester copolymer is a poly(vinyl acetate) or vinyl acetate copolymer, respectively. 6. The use, method, or composition according to any one of the preceding claims, wherein the vinyl ester copolymer is poly(ethylene-co-vinyl acetate). 7. The use, method or composition according to any one of the preceding claims, wherein the processing aid further comprises a polyester or ester copolymer, and wherein the total amount of the poly(vinyl ester) or vinyl ester copolymer and the polyester or ester copolymer is 0.01-1.0% by weight, based on the total weight of the extrudable polyolefin composition, or the total amount is 1-45% by weight of the masterbatch composition. 8. The use, method, or composition according to any one of the preceding claims, wherein the polymer processing aid is substantially free of fluorine and / or substantially free of siloxanes. 9. The use, method, or composition according to any one of the preceding claims, wherein the poly(vinyl ester) or vinyl ester copolymer has a molecular weight greater than 5000 g / mol. 10. The use, method, or composition according to claim 7, wherein the polyester or polyester copolymer has a molecular weight greater than 5000 g / mol. 11. The use, method or composition according to any one of the preceding claims, wherein the polyester or ester copolymer is poly(lactic acid), poly(butylene terephthalate adipate), poly(butylene succinate co-butylene terephthalate), or poly(hydroxyalkanoate). 12. The use, method, or composition according to any one of claims 7-11, wherein the poly(vinyl ester) or vinyl ester copolymer and the polyester or ester copolymer are present in the polymer processing aid in a ratio of about 1:10 to about 10:1. 13. The use, method, or composition according to any one of the preceding claims further comprises a synergist selected from poly(alkylene oxide) or polymeric liquid phosphite antioxidants. 14. The use, method, or composition according to any one of the preceding claims, wherein the polyolefin is selected from: polyethylene, including high-density polyethylene, linear low-density polyethylene, or low-density polyethylene; or polypropylene, including homopolymer polypropylene, random copolymer polypropylene, or multiphase impact copolymer polypropylene; or combinations thereof. 15. The use, method, or composition according to any one of the preceding claims, wherein the masterbatch composition further comprises one or more polymeric additives selected from: hindered phenols, phosphites, metal stearates, hydrotalcite, zinc oxide, slip agents, anti-blocking additives, antistatic additives, ultraviolet absorbers, hindered amine light stabilizers, and combinations thereof, wherein the one or more polymeric additives are present in an aggregate amount of 5-95% by weight based on the total weight of the polyolefin composition. 16. An extruded polyolefin product produced using the composition, method, or use according to any one of claims 1-15.

Claims

1. A method for reducing or eliminating melt fracture or die lip build-up in an extrudable polyolefin extrusion process, comprising: polymer processing aid is present in an amount of 0.01 to 1.0 weight percent, based on the total weight of the polyolefin composition, and wherein the polymer processing aid comprises a poly(vinyl ester) or vinyl ester copolymer, provided that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content is greater than 60 weight percent, and wherein the polymer processing aid is substantially free of PFAS.

2. Use of a poly(vinyl ester) or vinyl ester copolymer as a polymer processing aid to reduce or eliminate melt fracture or die lip build-up in an extrudable polyolefin composition, wherein the polymer processing aid is present in an amount of 0.01 to 1.0 weight percent, based on the total weight of the polyolefin composition, provided that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content is greater than 60 weight percent, and wherein the polymer processing aid is substantially free of PFAS.

3. An extrudable composition comprising a polyolefin and a polymer processing aid, the polymer processing aid being present in an amount of 0.01 to 1.0 weight percent, based on the total weight of the polyolefin composition, and wherein the polymer processing aid comprises a poly(vinyl ester) or vinyl ester copolymer, provided that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content is greater than 60 weight percent, and wherein the polymer processing aid is substantially free of PFAS.

4. A masterbatch composition comprising a polyolefin and a polymer processing aid, the polymer processing aid being present in an amount of 1 to 45 weight percent, based on the total weight of the polyolefin composition, and wherein the polymer processing aid comprises a poly(vinyl ester) or vinyl ester copolymer, provided that when the poly(vinyl ester) or vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), the vinyl acetate content is greater than 60 weight percent, and wherein the masterbatch is substantially free of PFAS.

5. The use, method, or composition of any of the preceding claims, wherein the poly(vinyl ester) or vinyl ester copolymer is a poly(vinyl acetate) or vinyl acetate copolymer, respectively.

6. The use, method, or composition of any of the preceding claims, wherein the vinyl ester copolymer is a poly(ethylene-co-vinyl acetate), and the vinyl acetate content is greater than 60 weight percent.

7. The use, method, or composition of any of the preceding claims, wherein the processing aid further comprises a polyester or ester copolymer, and wherein the combined amount of the poly(vinyl ester) or vinyl ester copolymer and the polyester or ester copolymer is 0.01 to 1.0 weight percent, based on the total weight of the extrudable polyolefin composition, or the combined amount is 1 to 45 weight percent of the masterbatch composition.

8. The use, method, or composition of any of the preceding claims, wherein the polymer processing aid is substantially free of fluorine and / or substantially free of siloxane.

9. The use, method or composition of any preceding claim, wherein the poly(vinyl ester) or vinyl ester copolymer has a molecular weight greater than 5000 g / mol.

10. The use, method or composition of any preceding claim, wherein the polyester or polyester copolymer has a molecular weight greater than 5000 g / mol.

11. The use, method or composition of any preceding claim, wherein the polyester or ester copolymer is poly(lactic acid), poly(butylene adipate terephthalate), poly(butylene succinate-co- butylene terephthalate), or poly(hydroxyalkanoate).

12. The use, method or composition of any of claims 7-11, wherein the poly(vinyl ester) or vinyl ester copolymer and the polyester or ester copolymer are present in the polymer processing aid in a ratio of about 1 : 10 to about 10:

1.

13. The use, method or composition of any preceding claim, further comprising a synergist selected from a poly(oxyalkylene) or a polymeric liquid phosphite antioxidant.

14. The use, method or composition of any preceding claim, wherein the polyolefin is selected from polyethylene, including high density polyethylene, linear low density polyethylene, or low density polyethylene, or polypropylene, including homopolymer polypropylene, random copolymer polypropylene, or heterophasic impact copolymer polypropylene, or combinations thereof.

15. The use, method or composition of any preceding claim, wherein the masterbatch composition further comprises one or more polymer additives selected from hindered phenols, phosphites, metal stearates, hydrotalcites, zinc oxide, slip agents, anti-blocking additives, anti-static additives, ultraviolet light absorbers, hindered amine light stabilizers, and combinations thereof, wherein the one or more polymer additives are present in a combined amount of 5 to 95 weight percent, based on the total weight of the polyolefin composition.

16. An extruded polyolefin product produced using the composition, method or use of any of claims 1-15.

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