Polymer processing aids for polyolefin extrusion

Abstract

Extrudable compositions include a non-fluorinated polyolefin polymer and a polymer processing aid including a polyester polyol selected from a polyester triol, a polyester tetrol, a polyester pentol, a polyester hexol, a polyester heptol, a polyester octol, or a combination thereof. Advantageously, the polymer processing aid excludes traditional fluoropolymer processing aids while also reducing surface roughness on articles prepared from the extrudable compositions.

Description

POLYMER PROCESSING AIDS FOR POLYOLEFIN EXTRUSIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and all benefit of U.S. Provisional Patent Application No. 63 / 683,162, filed on August 14, 2024, the entire disclosure of which is fully incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure is directed to extrudable compositions including nonfluorinated polyolefin polymers and polymer processing aids and articles prepared from such compositions.BACKGROUND

[0003] Plastic extrusion is a high-volume manufacturing process in which raw plastic is melted and formed into a continuous profile. The extrusion process typically starts by feeding plastic material (pellets, granules, flakes, or powders) from a hopper into a barrel of an extruder. Inside the barrel, one or more turning screws transports the plastic material from the hopper (rear of the barrel) to the front of the barrel. The feed plastic is gradually melted by the mechanical energy generated by turning screws and by heaters arranged along the barrel. The molten plastic is then forced into a die, which gives the extruded product its profile.

[0004] Extruded polyolefin products, such as polyethylene (PE) films, sheets, tubings, etc., are a rapidly growing market. At high production rates of such products, critical shear stress is reached at the die walls during extrusion, which results in melt flow instability causing surface defects in the extruded polyolefin. These defects appear as jagged, rough extrudates or sharkskin formations visible on the surface of the extruded polyolefin. Fluoropolymers, such as polyvinylidene fluoride (PVDF), are traditionally used as process aids to reduce or eliminate such melt flow defects. Fluoropolymers, due to their low surface energy and affinity to the die wall, can create a temporary die coating that allows a low friction resin-die interface.

[0005] However, despite their performance, the impending regulatory restrictions around per-and polyfluoroalkyl substances (PF AS), including fluoropolymer processing aids, are pushing the market to identify and use non-fluorinated process aid alternatives. Hence, a continuing need exists for non-PFAS processing aids for polyolefin extruded products.SUMMARY

[0006] Advantages of the present disclosure include extrudable compositions that can be used to form extruded articles with reduced or minimal melt flow defects without using a traditional fluoropolymer processing aid. The extrudable compositions include non-fluorinated polyolefin polymers and polymer processing aids which are advantageously free of fluoropolymers and can reduce or eliminate melt flow defects of extruded articles prepared from such compositions.

[0007] In certain implementations, an extrudable composition can comprise: (a) a nonfluorinated polyolefin polymer; and (b) a polymer processing aid which comprises, or consists of, a polyester polyol selected from a polyester triol, a polyester tetrol, a polyester pentol, a polyester hexol, a polyester heptol, a polyester octol, or a combination thereof. The polymer processing aid can be about 0.02 wt% to about 5 wt%, based on a total weight of the extrudable composition. Further, the polymer processing aid can exclude a variety of other polymer processing aids such as fluoropolymers.

[0008] The extrudable composition disclosed herein may be produced and sold as pellets, formed in post-polymerization reactor finishing processes (such as extrusion of polymer product that is in an at least partially molten state, followed by pelletization). The polymer processing aid may be blended into the extrudable composition as part of this finishing process, such that the polymer pellets comprise the non-fluorinated polyolefin polymer and the polymer processing aid.

[0009] The polymer processing aid may help make the pellets easier to manipulate in downstream manufacturing processes (such as extrusion, rolling, blowing, casting, and the like). Adequate amounts of the polymer processing aid, among other things, may also help eliminate melt fractures in films made from the polymer pellets. This is particularly so for polymer pellets exhibiting relatively higher viscosity in extrusion processes. Melt fracture is 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 melt fracture, but all manifest as a very rough polymer surface which persists as the polymer crystallizes. Commonly in the blown film industry, 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 polyolefin polymer (e g., polyethylene).

[0010] Advantageously, a variety of extrudable compositions can be prepared and a variety of extruded articles can be obtained from the compositions of the present disclosure. Theextrudable compositions can be prepared by combining the non-fluorinated polyolefin polymer and the polymer processing aid. The extruded articles can be produced by extruding the compositions. Extrusion can be carried out at a temperature in the range of about 180 °C to about 280 °C, such as from about 180 °C to about 250 °C, for example. Advantageously, extruded articles can be produced from the extrudable compositions that do not have surface roughness visible to the naked eye.

[0011] In accordance with the present disclosure, one or more of the following features individually or combined can be included in the extrudable compositions. For example, the non-fluorinated polyolefin polymer can comprise a polyethylene, a polypropylene, or a combination thereof. In some aspects, the polyester polyol can have a number average molecular weight (Mn) greater than or equal to 350, such as in a range of about 500 to about 50,000. The polymer processing aid can include, or consist of, a polyester tetrol, polyester triol, or a combination thereof.

[0012] Additional advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only certain embodiments are shown and described, simply by way of illustration of carrying out certain subject matter. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent similar elements throughout and wherein:

[0014] FIGS. 1A, IB, 1C, ID, IE, and IF are images of a strand of extruded linear low density polyethylene (LLDPE) at various times from when a polymer processing aid was introduced to the extruded LLDPE. The images show the extruded strand just prior to addition of the processing aid (time 0, FIG. 1 A), and addition of the processing aid after 1 min., 5 min., 15 min., 30 min., and 45 min., FIGS. IB, 1C, ID, IE, and IF, respectively.

[0015] FIG. 2 is a graph showing the calculated clarity of blown films produced from extrudable compositions over time, at extrusion times of 0 min., 5 min., 10 min., 15 min., 20 min., and 25 min.DETAILED DESCRIPTION

[0016] The disclosure may be more fully appreciated by reference to the following description, including the following definitions and examples.

[0017] Certain features of the disclosed compositions and methods which are described herein in the context of separate aspects, may also be provided in combination in a single aspect. Alternatively, various features of the disclosed compositions and methods that are, for brevity, described in the context of a single aspect, may also be provided separately or in any sub-combination.

[0018] Unless otherwise defined herein, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

[0019] Unless otherwise expressly indicated, it is not intended that any method disclosed herein be construed as requiring that its steps be performed in a specific order, nor that any article set forth herein be construed as requiring specific orders or orientations to its individual components.

[0020] Unless otherwise expressly indicated, it is intended that any composition or mixture disclosed herein may comprise, consist essentially of, or consist of the disclosed components.

[0021] As used herein, the following terms and abbreviations, unless otherwise indicated, shall be understood to have the following meanings.

[0022] As used herein, including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise.

[0023] As used herein, including the appended claims, when a range of values is expressed, such range includes from the one particular value and / or to the other particular value. All ranges are inclusive and combinable. Further, reference to values stated in ranges includes each and every value within that range. The term “about” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass reasonable variations of the value.

[0024] As used herein, the term “roughness” when referring to a surface of an extrudate or an extruded article means the extrudate or the extruded article has defects, such as jagged distortions or sharkskin formations, visible to the naked human eye on any surface that contacted a die of the extruder, for example, as shown in FIGS. 1 A, IB, or 1C.

[0025] As used herein, the term “smooth” when referring to a surface of an extrudate or an extruded article means the extrudate or the extruded article is substantially free, or free, of roughness visible to the naked human eye on any surface that contacted a die of the extruder, for example, as shown in FIGS. IE or IF.

[0026] The present disclosure is directed to extrudable compositions that include one or more non-fluorinated polyolefin polymers and a polymer processing aid, also referred to as a polymer processing additive. The extrudable composition of the present disclosure can be prepared by adding polymer processing aid either directly or in the form of masterbatch in an extruder through a side feeder of the extruder and combining it with the polyolefin, e.g., a nonfluorinated polyolefin polymer, to form an article thereof.

[0027] Advantageously, a wide variety of non-fluorinated polyolefin polymers can be used to form the extrudable compositions and articles of the present disclosure. The non-fluorinated polyolefin polymers that can be included in the extrudable compositions of the present disclosure include, for example, a melt processible polymer prepared from a variety of alkenes such as ethylene, propylene, butene, hexene, octene, decene, methylpentene, octadecene and include, for example, a polyethylene such as a high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and ethylene copolymers with other olefins, a polypropylene such as a polypropylene homopolymer, and propylene copolymers with other olefins, a polybutene, a polymethylbutene, a polymethylpentene, etc., or any combination thereof. Such polyolefin polymers are particularly suited to forming extruded articles from the extrudable compositions of the present disclosure.

[0028] The quality of the extruded article is influenced by interactions between the extrudable composition and the extrusion die. Higher production rates generally lead to a roughened surface at a certain rate. Thus, the need to produce an extrudate with a smooth surface competes with the economic advantages of extruding and forming articles at high rates.

[0029] Advantageously, it has been discovered that a polymer processing aid that includes, or consists of, a relatively low molecular weight, branched polyester polyol terminated with at least three primary hydroxyl groups can be effective at preparing smooth melt extruded articles and with lower cost and without use of PF AS. It is believed that such polyester polyols have affinity to the metal die surface and can act alone to reduce melt flow defects of extruded articles. In any aspect, the polyester polyol may be aliphatic, such as polycaprolactone, polyvalerolactone, polylactic acid, poly-L-lactic acid, and any combination thereof.

[0030] In certain implementations, the polymer processing aid of the present disclosure includes, or consists of, branched polyester polyol terminated with at least three primaryhydroxyl groups. The polyester polyol polymer processing aid may be in liquid form at ambient temperature (e.g., about 20 °C) or a solid, wax-like form. The polyester polyol can be either used directly as a processing aid and introduced during extrusion of the polyolefin, or combined with a carrier to prepare a solid masterbatch, or both.

[0031] The polymer processing aid of the present disclosure should be in an amount sufficient to impart a smooth surface to an extruded article prepared from the extrudable composition. For example, the polymer processing aid of the present disclosure can be in an amount of at least about 0.02 wt% based on a total weight of the extrudable composition. In some aspects, the extrudable composition includes at least about 0.05 wt%, at least about 0.1 wt%, at least about 0.3 wt%, at least about 0.4 wt%, at least about 0.5 wt%, at least about 0.7 wt%, at least about 1 wt%, or at least about 1.5 wt%, and up to about 5 wt% of the polymer processing aid based on a total weight of the extrudable composition. In any aspect, the extrudable composition may include the polymer processing aid in an amount of from about 0.02 wt% to about 5 wt% based on a total weight of the extrudable composition, including from about 0.03 wt% to about 4.8 wt%, from about 0.05 wt% to about 4.6 wt%, from about 0.1 wt% to about 4.4 wt%, from about 0.2 wt% to about 4.2 wt%, from about 0.5 wt% to about 4.0 wt%, from about 0.4 wt% to about 3.8 wt%, from about 0.5 wt% to about 3.6 wt%, from about 0.6 wt% to about 3.4 wt%, from about 0.8 wt% to about 3.2 wt%, from about 1.0 wt% to about 3.0 wt%, from about 1.2 wt% to about 2.8 wt%, from about 1.4 wt% to about 2.6 wt%, from about 1.6 wt% to about 2.4 wt%, from about 1.8 wt% to about 2.2 wt%, and from about 1.9 wt% to about 2.0 wt%, including all subranges and endpoints therebetween.

[0032] In any aspect of the present disclosure, the polyester polyol may have a number average molecular weight (Mn) greater than or equal to 350, greater than or equal to 400, greater than or equal to 450, greater than or equal to 500, greater than or equal to 550, greater than or equal to 600, greater than or equal to 650, greater than or equal to 700, greater than or equal to 750, greater than or equal to 800, greater than or equal to 850, greater than or equal to 900, greater than or equal to 550, or greater than or equal to 1,000, as measured by gel permeation chromatography according to ASTM D6579-11. In any aspect, the polyester polyol may have a number average molecular weight (Mn) less than or equal to 50,000, less than or equal to 45,000, less than or equal to 40,000, less than or equal to 35,000, less than or equal to 30,000, less than or equal to 25,000, less than or equal to 20,000, less than or equal to 25,000, less than or equal to 20,000, less than or equal to 18,000, less than or equal to 15,000, less than or equal to 13,000, less than or equal to 12,000, less than or equal to 11,000, less than or equal to 10,000, less than or equal to 8,000, less than or equal to 6,000, less than or equal to 5,000,less than or equal to 4,000, less than or equal to 3,000, less than or equal to 2,000, less than or equal to 1,500, less than or equal to 1,200, less than or equal to 1,100, less than or equal to 1,000, less than or equal to 800, less than or equal to 600, or less than or equal to 400, as measured by gel permeation chromatography according to ASTM D6579-11. Accordingly, the polyester polyol may have a number average molecular weight (Mn) of, for example, from 350 to 50,000, from 400 to 10,000, from 450 to 8,000, from 500 to 50,000, from 500 to 10,000, from 500 to 4,000, from 500 to 2,000, from 500 to 1,100, from 1,000 to 20,000, from 1,000 to 12,000, or from 1,000 to 10,000, etc., as measured by gel permeation chromatography according to ASTM D6579-11.

[0033] Polyester polyols are polymers formed via condensation polymerization, typically between diacids and diols. The polymer backbone contains repeating ester units and multiple terminal hydroxyl (OH) groups, located at the polymer chain ends. F = functionality, referring to the number of terminal hydroxyl groups per molecule. Polyester polyol with three hydroxyl groups is triol (F=3), four hydroxyl groups tetrol (F=4), five hydroxyl groups pentol (F=5), six hydroxyl groups hexol (F=6), seven hydroxyl groups heptol (F=7), and eight hydroxyl groups octol (F=8). The increase in functionality leads to higher viscosity and reactivity.

[0034] In any aspect of the present disclosure, the polymer processing aid may comprise, or consists of, a polyester polyol selected from a polyester triol, a polyester tetrol, a polyester pentol, a polyester hexol, a polyester heptol, a polyester octol, or a combination thereof. For example, the polymer processing aid may consist of a polyester triol, a polyester tetrol, or a combination thereof.

[0035] In addition, the polymer processing aid of the present disclosure can include, or consists of, a polyester polyol of Formula (I) and / or Formula (II) as shown below.Formula (I) represents a polycaprolactone triol in which R is a polycaprolactone radical with a hydroxyl end group and Ri is an alkyl, such as a C i-s alkyl group, its functionality (F) beingdefined by the presence of 3 hydroxyl groups; Formula (II) represents a polycaprolactone tetrol having a similar backbone to Formula (I) but with 4 hydroxyl groups present. The repeating unit “n” can be 1 to about 15. In an aspect of the present disclosure, the polyester polyol may include, or consists of, a polyester tetrol (e.g., polycaprolactone tetrol), a polyester triol (e.g., polycaprolactone triol), or a combination thereof. Such polyester polyols can be prepared by ring opening polymerization of caprolactone, e.g., s-caprolactone, using a branched initiator such as pentaerythritol, trimethylolpropane, 1-lactide, dipentaerythritol, poly-L-lactide (PLLA), tripentaerythritol, or a combination thereof. Some useful polyester polyols that can be used as polymer processing aids according to the present disclosure are commercially available. For example, commercially available polyester polyol can be obtained from Ingevity as CAPA 4101 (Mn ~ 1000) (liquid), other tetrols can be selected with higher molecular weights including Mn ~ 2690 (wax / solid); Mn -4000 (wax / solid); Mn - 6000 (wax / solid); Mn -8000 (wax / solid); Mn - 9250 (wax / solid); Mn - 12000 (wax / solid); Mn - 15000) (wax / solid); these polycaprolactone tetrols are initiated with pentaerythritol; CAPA 3050 (Mn - 540) (liquid), a poly caprolactone triol initiated with trimethylolpropane; CAPA 3091 (Mn - 900) (liquid), a polycaprolactone triol initiated with trimethylolpropane. Other examples of poly(s- caprolactone) (PCL) include polycaprolactone pentol, initiated with poly-L-lactide (PLLA) and tripentaerythritol, Mn - 17600 (solid); poly caprolactone hexol, a 6-arm star-shaped poly(s- caprolactone) that can be synthesized via ring-opening polymerization (ROP) of 8-caprolactone using dipentaerythritol as an initiator, Mn - 6200 or Mn - 7600 (solid); hexol synthesized via ROP of L-Lactide and dipentaerythritol, Mn range - 4485 to 43493; poly caprolactone octol, an 8-arm star-shaped poly(s-caprolactone) that can be synthesized via ring-opening polymerization (ROP) of poly-L-lactide (PLLA) using tripentaerythritol as an initiator, Mn - 17600 (solid). While the use of polycaprolactones as a processing aid has been generally disclosed (see, e.g., US 8,053,526), they tend to be used in combination with other polymer processing aids and there does not appear a distinction among diols and higher numbers of hydroxyl end groups.

[0036] Advantageously, the polymer processing aids of the present disclosure can exclude, or can be substantially free of, or free of, per-and polyfluoroalkyl substances including a fluoropolymer processing aid. As used herein, substantially free of a component means less than about 0.1 wt% or even less than 0.01 wt% of the component relative to the total amount of polymer processing aid and free of a component means at a level of an impurity such as less than 0.001 wt% of the component relative to the total amount of polymer processing aid. Such fluoropolymer processing aids that can be excluded from the polymer processing aids of thepresent disclosure include, for example, a chlorotrifluoroethylene, tetrafluoroethylene and perfluoroalkyl perfluorovinyl ethers, a fluoroelastomer such as Viton, fluorinated ethylene propylene, polyvinylidene fluoride, etc.

[0037] The polymer processing aids of the present disclosure advantageously can be substantially free, or free, of any one or more of other polymer processing aids such as polycaprolactone diols (e.g., CAPA 2403D), silanes, siloxanes, and silicones, polyamides or copolymers thereof, polyethylene glycol, etc. Reducing the number and type of polymer processing aids to the polyester polyols of the present disclosure simplifies processing and can reduce costs.

[0038] While the polymer processing aids of the present disclosure include, or consist of, polyester polyols, other additives may optionally be included with the extrudable composition. For example, other additives can be included in the extrudable composition of the present disclosure that are not directed to surface roughness of the extrudate including antioxidants, antiblocking agents, light stabilizers, pigments, fillers blowing agents, reinforcing agents (such as mica, CaCCh, talc, clays, glass fibers), nucleating agents, plasticizers, flame retardants, nanofillers, UV additives, lubricants and waxes etc. In some aspects, the extrudable composition may be free or essentially free (i.e., less than 0.5 wt.%) of solid lubricants, such as boron nitride, graphite, graphene, and the like. Such solid lubricants may compromise the optical clarity of the extruded articles.

[0039] The polymer processing aid of the present disclosure may be a one-pack (or one part) polymer processing aid (PPA) comprising the polyester polyol and one or more of the other additives described herein. For example, the one-pack PPA may comprise the polyester polyol, a lubricant, an antioxidant, and a UV absorber. The polyester polyol may be present in an amount of 50 wt% to 99 wt% based on the total weight of the one-pack PPA, including 50 wt% to 95 wt%, 55 wt% to 90 wt%, 60 wt% to 85 wt%, 65 wt% to 80 wt%, and 70 wt% to 75 wt%, including all subranges and endpoints therebetween. The other additives, individually or collectively, may be present in an amount of 1 wt% to 50 wt% based on the total weight of the one-pack PPA, including 5 wt% to 50 wt%, 10 wt% to 45 wt%, 15 wt% to 40 wt%, 20 wt% to 35 wt%, and 25 wt% to 30 wt%, including all subranges and endpoints therebetween.

[0040] In certain implementations, extrudable composition of the present disclosure can be prepared by combining the non-fluorinated polyolefin polymer and about 0.02 wt% to about 5 wt% of the polymer processing aid, based on a total weight of the composition. In such implementations, the polymer processing aid includes, or consists of, a polyester polyol selected from a polyester tetrol, a polyester triol, or a combination thereof. As explained above,the polymer processing aid can exclude a fluoropolymer as well as other polymer processing aids.

[0041] The combination can be carried out in any of a variety of ways. For example, the non-fluorinated melt processible polymer such as polyolefin and the polymer processing aid can be combined together by blending with a compounding mill, a Banbury mixer, or a mixing extruder in which the polymer processing aid is uniformly distributed throughout the nonfluorinated melt processible polymer. In other implementations, extrudable composition of the present disclosure can be prepared by admixing (e.g., pre-mixing), or pre-blending (e.g. dry blending or melt blending) the polymer processing aid with a polyolefin followed by extrusion of the admixed polyolefin. In addition, or as an alternative, one or more components of a polymer processing aid either directly or in the form of a masterbatch can be co-fed via side feeder with a polyolefin to an extruder.

[0042] The polymer processing aid, particularly when it is a one-pack polymer processing aid (PPA), can be added to a polymer product (e.g., polymer granules and / or slurry) exiting a polymerization reactor to form a pre-finished polymer mixture in or upstream of a compounding extruder. The pre-finished polymer mixture therefore includes the polymer and the polymer processing aid. The pre-finished polymer mixture may be a polymer melt (e.g., formed in or just upstream of a compounding extruder). The mixture is then extruded and optionally pelletized to form a further polymer composition (e.g., polymer pellets) comprising the polymer and the polymer processing aid, including the polyester polyol and other additive(s).

[0043] The extrudable composition, including the polymer processing aid and the nonfluorinated melt processible polymer, can be used, for example, in the form of a powder, a pellet, and / or a granular composition. The components can be mixed at a temperature above the melting point or softening point of the melt processible polymer, though it is also feasible to dry -blend the components in the solid state as particulates followed by feeding the dry blend into a twin-screw melt extruder.

[0044] In addition, and for ease of processing, the polymer processing aids of the present disclosure can be in the form of a masterbatch when introduced to the non-fluorinated polyolefin polymer to form the composition which is to be extruded. A masterbatch is a mixture of the polymer processing aid in a diluent polymer. The diluent polymer can be the same non- fluorinated polyolefin polymer that is to be extruded, or it can be a different, but it should be compatible with non-fluorinated polyolefin polymer that is to be extruded. Masterbatches typically contain 1-50 wt., or 1-30 wt.%, of the polymer processing aid (based on the totalweight of the masterbatch). Masterbatches can be made, for example, by mixing the appropriate amount of the polymer processing aid with diluent polymer in a mixer, such as a Banbury(E) mixer. Mixing can occur at a temperature above the melting point of the diluent polymer. For example, one or more components of a polymer processing aid can be added to a thermoplastic polyolefin to prepare a masterbatch of the polyolefin containing the one or more components of a polymer processing aids. The resulting polyolefin masterbatch can then be used to introduce the one or more components of a polymer processing aid into a non-fluorinated polyolefin polymer in any conventional manner prior to extrusion of a non-fluorinated polyolefin polymer (e.g. dry blending or melt blending) or during the extrusion of a non- fluorinated polyolefin polymer (e.g. co-feeding via side feeder).

[0045] The rate at which the polymer processing aid is fed to an extruder is controlled so that the level of the polymer processing aid in the resulting extrudable composition is about 0.02 wt% to about 5 wt%, based on the total weight of the extrudable composition, such as, for example, about 0.03 wt.% to about 4 wt.%, about 0.05 wt.% to about 3 wt.%, about 0.1 wt.% to about 2.5 wt.%, and about 0.5 wt.% to about 2 wt.%.

[0046] In certain implementations, extrudable composition of the present disclosure can be extruded into an article. Processes for forming an extruded article can include extruding a composition including: (a) a non-fluorinated polyolefin polymer; and about 0.02 wt% to about 5 wt%, based on a total weight of the composition, of a polymer processing aid which includes a polyester polyol selected from a polyester tetrol, a polyester triol, or a combination thereof. As explained above, the polymer processing aid can exclude certain traditional polymer processing aids such as a fluoropolymer. Melt processing typically can be performed at a temperature from about 180 °C to about 280 °C, such as at a temperature in the range of about 180 °C to about 250 °C, or of about 200 °C to about 240 °C. The operating temperatures for extrusion depend upon the melting point, melt viscosity, thermal stability of the blend, etc. Extruding the composition into an article can be carried out using a variety of extruders such as via pellet mill extrusion, ram extrusion, film extrusion, pipe, wire, and cable extrusion, fiber and strand production, plastic netting extrusion, etc.

[0047] When the composition is extruded into a blown film, the film may present good clarity. For example, by 25 minutes of extrusion time, the blown film may achieve a clarity of 80 % or more, 85 % or more, or 90 % or more at a nominal film thickness of 0.100 mm, as determined from % haze measurements in accordance with ASTM D1003.

[0048] When the extrudable composition is formed into a polymer product by a continuous extrusion process, it may exhibit a reduced time to clear and conditioning time. Time to clearrefers to the elapsed time after extrude start-up until an extruded article exhibits 100 % clarity with no melt flow defects. Conditioning time refers to the elapsed time after extrude start-up until an extruded article exhibits an acceptably low degree of melt flow defects. The extrudable composition may have a time to clear and / or a conditioning time of 45 minutes or less, 40 minutes or less, 35 minutes or less, 30 minutes or less, 25 minutes or less, or 20 minutes or less.EXAMPLES

[0049] The following examples are intended to further illustrate certain aspects of the subject technology and are not limiting in nature. Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances and procedures described herein.

[0050] Various polymer processing aids were tested with a non-fluorinated polyolefin polymer. The experiments begin by establishing a stable, rough surface (sharkskin) condition. Then, the polymer processing additive is introduced while the polyolefin is being extruded through the die and the time to eliminate the sharkskin is measured till 45 mins. A Leistritz corotating twin screw extruder was used which had an 18 mm diameter with an L / D of 40. The extruder was fitted with a die that has a single hole of 2.75 mm diameter. The taper length from the extruder breaker plate to the die hole entrance is 10.50 mm. The land length of the circular hole is 2 mm.

[0051] For example, FIGS. 1A through IF illustrate images of a strand of extruded polyolefin having a processing aid in the form of a masterbatch was added through side feeder to the extruded polyolefin. The effect of processing aid on strand of extruded polyolefin was evaluated till 45 mins after the addition of processing aid. For this example, the polyolefin was a linear low density polyethylene (LLDPE) Dowlex 2045G with a Melt Index of 1.0 g / 10 min. at 190 °C / 2.16 kg mass load and the processing aid was in the form of a Masterbatch of 5 % CAPA 4101 / 95 % Novapol PI 2024 A LLDPE, Melt Index of 20 g / 10 min. at 190 °C / 2.16 kg mass load. Effective concentration of CAPA 4101 in LLDPE was about 0.5 %. The masterbatch was co-fed in a Leistritz co-rotating twin screw extruder, general purpose screw design, L / D = 40. The barrel temperature was set to about 200 °C. As shown by the image of FIG. 1A, the extruded strand just prior to addition of the processing aid at time 0 exhibits the rough (sharkskin) surface, which is evident with the naked eye. The surface of the extruded polyolefin continues to exhibit a roughened surface for the next 5 minutes after introduction of the polymer processing additive (FIGS. IB, 1C) for this experiment. However, after about 15minutes from the introduction of the polymer processing additive, the extruded polyolefin strand is smooth around most of its circumference (FIG. ID) and becomes smooth around the entire circumference at around 23 minutes (FIG. IE, image at 30 minutes) and continues to remain smooth around its entire circumference (FIG. IF, image at 45 minutes) during the extrusion of the polyolefin.

[0052] Prior to discovering the advantages of a polymer processing aid that includes or consists of a polyester polyol selected from a polyester tetrol, a polyester triol, or a combination thereof, a number of other processing aids were screened.

[0053] The screening experiment (example ID from SEI to SE9) focused on polymers or solid additives that were not antioxidants or lubricants. Some of the polymer processing aids considered included slip agents and, polar materials to adhere to the metal die surface (“stick” agents). Table 1 shows the polymer processing aids tested and observations as to effectiveness for an extruded composition extruded with an extruder having a barrel temperature of 240 °C. For these experiments, 10 % polymer processing additive masterbatches (i.e. 10 wt.% polymer processing aid + 90 wt.% diluent polymer / carrier) were added to the extruder via a side feeder (separate feeder) for an effective concentration of 0.50 % in an extruded LLDPE.Table 1. Extruded LLDPE with various polymer processing aid at 240 °C.

[0054] The screening experiments revealed that only polycaprolactone (example SE6) could significantly improve surface roughness. For example, polycaprolactone diol (CAPA 6800) showed better performance compared to other aids in Table 1 in terms of reducing sharkskin effect but did not achieve total smoothness around the entire circumference of the strand.

[0055] The next experiments evaluated different versions of polycaprolactones, including polycaprolactone diols (comparative examples CE1 to CE3), polycaprolactone triol with number average molecular weight around 300 (comparative example CE4), poly caprolactone triol with number average molecular weight around 540 or 900 (inventive examples IE1 and IE2) and poly caprolactone tetrol with number average molecular weight around 1000 or 2690 (inventive examples IE3, IE4, and IE5). The polyols terminated with three or more primary hydroxyl groups were effective in eliminating surface roughness, particularly when the number average molecular weight was above 300. The data is provided in Tables 2 and 3 below.Table 2. Extruded LLDPE with various polycaprolactone polymer processing aids at 200 ofThe final concentration of polymer processing additive in LLDPE was 0.5%.Table 3. Extruded LLDPE with various polycaprolactone polymer processing aids at 200

[0056] Further, the data in Table 2 show that by using a poly caprolactone tetrol polymer processing aid, the time period to achieving an extrudate with a smooth surface is shorter. To minimize waste and reduce costs, a very short conditioning time is desirable. Conditioning time as used herein refers to the elapsed time after extrude start-up until an extruded article exhibits an acceptably low degree of melt flow defects.

[0057] In addition, the data in Table 3 show that by using a poly caprolactone triol or tetrol polymer processing aid, the torque % can be significantly reduced after introducing the polymer processing aid, e.g., a reduction in torque of greater than 20 %. Significantly reducing the torque, as in the examples above, provides a significant cost savings in power to producethe extruded article. As further shown by the data of Tables 2 and 3, a polymer processing aid which includes a polyester polyol selected from a polyester tetrol or a polyester triol can effectively reduce surface roughness of a polyolefin extruded article even without traditional fluoropolymer processing aids.

[0058] Furthermore, polymer processing aid (PPA) additives can improve clarity in polyethylene (PE) films produced, particularly in the context of blown film extrusion by reducing surface defects and improving film formation. To demonstrate the benefit of using a polymer processing aid in PE, the performance of the resulting non-fluorinated blown PE film was assessed in terms of the level of haze and calculated clarity of the film produced.

[0059] The test was designed to compare the performance of polycaprolactones disclosed herein, IE3 CAPA 4101 tetrol with Mn ~ 1000 and a higher molecular weight IE6 PCL tetrol initiated with pentaerythritol with Mn ~ 9250, with comparative examples, a commercially available fluorinated PPA Daikin DA-910 (CE5) and poly caprolactone diol CAPA 2403D (CE3) at the same addition rate.Table 4. Compositions used to produce PE blown films.

[0060] The compositions from Table 4 were prepared with thermoplastic carrier 1 MFI LLDPE to produce blown film samples. The films were produced on a blown film line which included a 63.5 mm diameter single screw extruder with a length / diameter ratio of 24: 1. The 101.6 mm diameter film die had a gap of 1.8 mm, which yielded a nominal film thickness of 0.100 mm.

[0061] The procedure below was used to produce the examples in Table 4:1. Establish melt fracture with a 1 MFI LLDPE by using a screw RPM of 50, and a flat temperature profile of 180 °C.2. Empty the feed throat. Introduce the LLDPE and polymer process aid blend into the feed throat of the extruder, with the extruder running.3. Allow for 90 seconds of residence time.4. Set the stopwatch. Begin collecting film samples at time = 0, 5, 10, 15, 20, 25 minutes.5. Purge the extruder with 100% commercial purging compound for 30 minutes duration to ensure it is fully clear.6. Re-introduce the 1 MFI LLDPE and re-establish melt fracture.7. Repeat steps #2 to #6 for all compositions.

[0062] Haze values of the films produced by the steps above were obtained using BYK- Gardner Haze-Gard Plus, model 4725 using Illuminant CIE-C. For each film specimen, the % haze measurements were taken in accordance with ASTM DI 003, Procedure A.

[0063] The % haze was measured at 8 locations across the 24” width of film. The meter and software convert the % haze to % clarity (these two quantities are not simply inverses of each other). The film thickness was measured the at the same 8 locations across the 24” width of film. All % clarity measurements for each of the specimens were normalized to one film thickness. The average value and standard deviation are reported.Table 5. Clarity values over time.

[0064] Referring to Table 5 and FIG. 2, comparing the clarity values of the CE5 (with the commercially available fluorinated PPA) with IE3 (with a polycaprolactone tetrol disclosed herein), IE3 presented significantly improved clarity level at every time interval, in particular by 25 minutes. The performance of IE6 was similar to CE5, indicating that the polymer processing aids disclosed herein, while being PFAS-free, may successfully achieve a performance comparable to commercially available fluorinated PPA.

[0065] Comparing the performance of the polycaprolactone tetrols (IE3 and IE6) with diol (CE3), it can be clearly seen that the diol did not perform as well, only reaching a clarity level of 80.65 % by 25 mins, compared to 90.8 % (IE3) and 85.18 % (IE6) respectively.

[0066] It is believed that polyester polyols with a functionality (F) of 2 or less (e.g., diols) have some affinity to the metal die surface and can act alone to reduce melt flow defects of extruded articles. Polyester triols (F=3), polyester tetrols (F=4), and polyester polyols with higher F may have even more affinity to the metal die surface to further reduce melt flow defects. On the other hand, polyester polyols with lower F (e.g., diol), which are less polar, may be more compatible with some polyolefin polymers such as LLDPE; polyester polyols with higher F (e.g., triols and tetrols), being more polar, may be less compatible as they migrate out of the molten polymer faster and to a greater extent.

[0067] In a further set of experiments, the performance of polyester polyol as a polymer processing aid (PPA) was evaluated for the extrusion of polyolefin polymer resulting in polymer pellets comprising the PPA, which can be later used down-stream, such as for moulding into articles. A polymer processing aid was prepared as a one-pack PPA as detailed in Table 6, with poly caprolactone tetrol (number average molecular weight around 1000) as the primary ingredient.Table 6. One-pack polymer processing aid.

[0068] The other additives (lubricant, antioxidant, and UV absorber) were selected from additives commonly used in polyolefin production, which are expected to have no or little impact on the time to clear performance as described below. On the other hand, the polyester polyol should demonstrate an impact on the time to clear performance if the PPA chemistry is successful.

[0069] The procedure below was used to prepare the one-pack PPA.1. Charge a steel beaker with the CAPA 4101 tetrol poly caprolactone.2. Heat the CAPA 4101 tetrol poly caprolactone to 80 °C to facilitate easy addition of solid additives.3. While stirring, add the lubricant, the antioxidant, and the UV absorber. These solid additives will not melt but simply be dispersed in the liquid CAPA 4101 tetrol polycaprolactone. They will not be degraded by this heat history.4. Cool mixture to 23 °C if it is to be stored; keep at 80 °C if it will be added to the LLDPE (see below).

[0070] The procedure below was used to add the one-pack PPA to LLDPE polymer.1. Charge an intensive mixer (e.g. Henschel mixer) with the LLDPE pellets so that it occupies 70-80% of the mixer volume.2. Heat the one-pack PPA to 80 °C.3. Close the mixer and set the blade RPM to the lowest setting possible.4. Start the mixer and add the hot one-pack PPA via the liquid injection port on the mixer. The addition can best be done with a syringe.5. Mix for 2 minutes and then discharge the coated LLDPE pellets.

[0071] Next, the LLDPE pellets blended with the one-pack PPA were let-down into Dowlex 2045G LLDPE polymer resin at 0.625% to yield a content of 5,000 ppm for CAPA 4101 tetrol poly caprolactone, using a twin-screw extruder with 60 / 1 Length / Diameter (L / D). The resulting pre-compound was then pelletized.

[0072] The pre-compound pellets were then evaluated at 100% (no letdown) being continuously extruded at 200 °C using a twin-screw melt extruder with a 40 / 1 Length / Diameter (L / D). The time to clear evaluation was measured as a visual assessment of the polymer, i.e.,the elapsed time after extrude start-up until an extruded article exhibits 100 % clarity with no melt flow defects.

[0073] In the procedures outlined above, the one-pack PPA pre-compound experienced heating two times, once during preparation the one-pack PPA compounding steps and once during the time to clear evaluation. In contrast, real industry processes for manufacturing extruded articles may include heating polymer processing aids only once during extrusion. However, this difference in heat history should not impact the performance of the polymer process aid in which the effective components are thermally stable.Table 7. Time to clear of LLDPE extruded at 200 °C with pre-compound containing the one-pack polymer processing aid.

[0074] As shown in Table 7, the one-pack PPA is suitable as a process aid for continuous processes with a short time period (30 minutes) until achieving an extrudate with a smooth surface. Accordingly, extrudable compositions comprising the one-pack PPA are expected to have a short conditioning time, such as 30 minutes or less, which refers to the elapsed time after extrude start-up until an extruded article exhibits an acceptably low degree of melt flow defects. Therefore, the extrudable compositions disclosed herein may help minimize waste and reduce costs with short time to clear and conditioning time.

[0075] Every document cited herein is incorporated herein by reference in its entirety unless otherwise specified. The citation of any document is not to be construed as an admission that it is prior art with respect to any invention disclosed or claimed herein. To the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0076] Only certain features and aspects of the present disclosure and examples of their versatility are shown and described in the present disclosure. It is to be understood that the technology disclosed herein is capable of use in various other combinations and environments and is capable of changes or modifications. Thus, for example, those skilled in the art willrecognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances, procedures and arrangements described herein. Such equivalents are considered to be within the scope of the invention and are covered by the following claims.

Claims

CLAIMSWhat is claimed is:

1. A method for forming a polymer product comprising: blending a polymer processing aid with a polymer composition to obtain a polymer mixture; and forming the polymer mixture into a polymer product, wherein the polymer processing aid comprises a polyester polyol selected from a polyester triol, a polyester tetrol, a polyester pentol, a polyester hexol, a polyester heptol, a polyester octol, and a combination thereof, wherein the polyester polyol has a number average molecular weight (Mn) greater than or equal to 350; wherein the polymer processing aid excludes a fluoropolymer, and wherein the polymer product comprises from 200 to 50,000 ppm of the polyester polyol.

2. The method of claim 1, wherein the polymer composition comprises a polyolefin resin.

3. The method of claim 2, wherein the polyolefin resin comprises a polyethylene, a polypropylene, or a combination thereof.

3. The method of any one of the preceding claims, wherein the polyester polyol has a number average molecular weight (Mn) in the range of about 500 to about 50,000.

4. The method of any one of the preceding claims, wherein the polyester polyol has a number average molecular weight (Mn) in the range of about 1,000 to about 12,000.

5. The method of any one of the preceding claims, wherein the processing aid consists of the polyester triol, polyester tetrol, or a combination thereof.

6. The method of any one of the preceding claims, wherein the polyester is a polycaprolactone, polyvalerolactone, polylactic acid, poly-L-lactic acid, or any combination thereof.

7. The method of any one of the preceding claims, wherein the polyester tetrol is a poly caprolactone tetrol.

8. The method of claim 7, wherein the polycaprolactone tetrol is derived from caprolactone and pentaerythritol as an initiator.

9. The method of any one of the preceding claims, wherein the polycaprolactone tetrol has a number average molecular weight (Mn) range of about 1,000 to 12,000.

10. The method of any one of the preceding claims, wherein the polyester triol is a poly caprolactone triol.

11. The method of claim 10, wherein the poly caprolactone triol is derived from caprolactone and trimethylolpropane as an initiator.

12. The method of any one of the preceding claims, wherein the polycaprolactone triol has a number average molecular weight (Mn) in the range of about 500 to about 2,000.

13. The method of any one of the preceding claims, wherein the polymer processing aid further comprises an additive selected from a lubricant, an antioxidant, a UV absorber, or a combination thereof.

14. The method of any one of the preceding claims, wherein the polymer mixture is formed into the polymer product by a continuous extrusion process.

15. The method of claim 14, wherein the continuous extrusion process has a time to clear of 30 minutes or less.

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