CN118019794A - Fluorine-free polymer processing aid comprising polyethylene glycol - Google Patents

Abstract

Provided herein are polymer compositions comprising a polymer and a polyethylene glycol (PEG) based Polymer Processing Aid (PPA). The polyethylene glycol may have a molecular weight of less than 40,000 g/mol. The polymer may be a C ₂-C₆ olefin homopolymer or a copolymer of two or more C ₂-C₂₀ alpha-olefins, and the polymer composition may take the form: polymer pellets; a polymer melt; reactor grade polymer pellets and/or polymer slurry; or other forms of polymer compositions containing the PPA and optionally one or more other additives. The polymer composition is preferably free or substantially free of fluorine, including PPA based on fluoropolymers.

Description

Fluorine-free polymer processing aid comprising polyethylene glycol

Cross Reference to Related Applications

The present application claims the benefit of U.S. provisional application 63/261,908 entitled "Fluoine-Free Polymer Processing Aids [ non-fluorinated polymer processing aid ]" filed on month 30 of 2021, and also claims the benefit of U.S. provisional application 63/266,782 entitled "Fluoine-Free Polymer Processing Aids [ non-fluorinated polymer processing aid ]" filed on month 14 of 2022, and also claims the benefit of U.S. provisional application 63/261,640 entitled "Fluoine-Free Polymer Processing Aids Including Polyethylene Glycols [ non-fluorinated polymer processing aid including polyethylene glycol ]" filed on month 9 of 2022, and also claims the benefit of U.S. provisional application 63/367,640 entitled "Fluoine-Free Polymer Processing Aids Including Polyethylene Glycols [ non-fluorinated polymer processing aid including polyethylene glycol ]" filed on month 14 of 2022, and also claims the benefit of U.S. provisional application 63/309,859 entitled "Fluoine-Free Polymer Processing Aid Blends [ non-fluorinated polymer processing aid blend ]" 2022 of 2027 of 2022, and claims 3 of U.S. 5,35 of U.S. Pat. No. 2, and claims 3 of "Fluoine-35 of" 35 of year 35, and claims 3 to be based on the benefit of the polymer processing aid of the disclosure of "Fluoine-3675 of the application" filed on month 14 of 2022, these applications are incorporated by reference in their entirety.

Technical Field

The present disclosure relates to additives for polyolefin polymers (e.g., polyethylene), as well as the polymers themselves, methods of making the same, and articles made therefrom.

Background

There is a high demand for polyolefin polymer compositions for a number of applications including various films (such as cast films, shrink films and blown films), sheets, films such as geomembranes, bags, pipes (e.g., heat resistant polyethylene (PE-RT) pipes, utility pipes and gas distribution pipes), rotational molded parts, blow molded flexible bottles or other containers, and various other blow molded/extruded articles such as bottles, barrels, tanks and other containers. These applications are typically made of, for example, polyethylene polymers.

Polyolefin polymers are most commonly produced and sold in pellet form, which are formed in post-polymerization finishing processes (e.g., extrusion of the polymer product in an at least partially molten state, followed by pelletization). As part of this finishing process, additives are typically blended into the polymer product such that the polymer pellets comprise the polymer itself and one or more additives.

Common additives, particularly for polymers intended for use as films, bags and other similar articles, such as polyethylene, include Polymer Processing Aids (PPA) that help to facilitate handling of the pellets in downstream manufacturing processes (e.g., extrusion, roll-in, blow-molding, casting, etc.). Among other things, sufficient PPA helps to eliminate melt fracture in films made from polymer pellets. This is especially true for polymer pellets that exhibit relatively high viscosity in the extrusion process. Melt fracture is a mechanically induced melt flow instability that occurs, for example, at the exit of an extrusion die and typically under high shear rate conditions. Pinhole, line and annular die geometries are geometries that can induce melt fracture. There are different mechanical states describing PE melt fracture, but all appear as very rough polymer surfaces that persist with polymer crystallization. Typically in the blown film industry, rough arrays of shark skin-like patterns, typically having feature sizes on the scale of from mm to cm, are formed on the film surface and they depend on both the flow characteristics and rheology of the polyolefin polymer (e.g., polyethylene).

Melt fracture can adversely affect film properties, distort transparency, and reduce thickness uniformity. Thus, as indicated, the polymer grade at which the fusible body breaks is generally dependent on PPA.

The PPA most commonly used is or includes a fluoropolymer (fluorine-containing polymer). However, it is desirable to find alternative PPAs that do not contain fluoropolymers and/or fluorine while maintaining the effectiveness of fluoropolymer-based PPAs in preventing melt fracture.

Some references that may be of interest in this regard include: U.S. Pat. nos. 10,982,079、10,242,769、10,544,293、9,896,575、9,187,629、9,115,274、8,552,136、8,455,580、8,728,370、8,388,868、8,178,479、7,528,185、7,442,742、6,294,604、5,015,693、 and 4,540,538; U.S. patent publication nos. 2005/007044, 2008/0132654, 2014/0182882, 2014/024474, 2015/0175785, 2020/0325314; and WO 2020/146351;EP 3234004;WO 2011/028206、CN 104558751、CN 112029173、KR10-2020-0053903、CN 110317383、JP 2012009754A、WO 2017/077455、CN 108481855、CN 103772789.

Disclosure of Invention

The present disclosure relates to polymer compositions, methods of making the same, and articles comprising and/or made from these polymer compositions. In particular focus, these polymer compositions may be polyolefin compositions, such as polyethylene compositions. The polymer composition may further comprise PPA that is free or substantially free of fluorine; and similarly, the polymer composition may be free or substantially free of fluorine. In this context, "substantially free" allows for trace amounts (e.g., 10ppm or less, preferably 1ppm or less, such as 0.1ppm or less) of fluorine (e.g., as an impurity), but in amounts well below the amounts that would be intentionally included in the polymer composition via such additives (e.g., about 100ppm fluorine atoms based on the mass of the polymer product in typical cases where such additives are included). In various embodiments, the polymer composition may be, for example, a polymer pellet; polymer melt (as would be formed in an extruder such as a compounding extruder); reactor grade polymer pellets and/or polymer slurry; or other forms of polymer compositions containing the PPA and optionally one or more other additives.

The disclosure also relates to films and/or other end use articles made from such polymer compositions, and in particular instances may relate to cast or blown films, preferably blown films. Thus, the polyolefin compositions (e.g., polymer pellets) of the various embodiments, and/or films or other articles made therefrom (e.g., blown films) are themselves free or substantially free of fluorine (or at least free or substantially free of fluorine-based PPA). Fluorine-based PPA as used herein is a fluorine-containing polymer processing aid or other polymer additive.

The inventors of the present invention found that polyethylene glycol (PEG) is an advantageous alternative to fluorine-based PPA in polyolefin compositions; also, in particular embodiments, the PEG-based PPA comprises a PEG having a molecular weight of less than 40,000g/mol, such as in the range of from 1,500 to 35,000g/mol, such as 5,000 to 12,000g/mol, or 5,000 to 20,000 g/mol. The PPA based on PEG preferably comprises at least 80wt% (based on the total mass of PPA), more preferably at least 90wt%, or at least 99wt% PEG. The PEG-based PPA may consist of or consist essentially of PEG. Thus, the polyolefin compositions of the various embodiments comprise an olefin-based polymer and a PPA comprising at least 90wt% or at least 99wt% of polyethylene glycol having a molecular weight of 1,500 to 40,000 g/mol. Also, while certain embodiments of the polymer composition may contain other additives (even other PPAs, such as fluorine-based PPAs) in addition to the PEG-based PPAs, in preferred embodiments-as noted immediately above-the polymer composition is free or substantially free of fluorine. According to some embodiments, the polymer composition is also free or substantially free of other PPAs.

The PEG (or PPA comprising at least 80wt%, at least 90wt%, or at least 99wt% PEG) may be present in the polymer composition in an amount ranging from about 300ppm to about 15000ppm, more preferably about 300ppm to about 2000ppm, or about 600ppm to about 1200ppm, based on the mass of the polymer in the polymer composition, but in the case of other PPAs (e.g., conventional fluorine-based PPAs, or more preferably other non-fluorine-containing or substantially non-fluorine-containing PPAs), lower amounts (e.g., 50 or 100ppm to 200, 300, 400, or 500 ppm) may be employed. As noted, other additives (e.g., antioxidants, stabilizers such as UV stabilizers, catalyst neutralizers, and other additives known in the polymerization arts) may also optionally be present in the polymer composition. The polymers and PEG-based PPAs included in the polymer compositions of the various embodiments are discussed in more detail below.

The inventors of the present invention have also unexpectedly found that the process of introducing PEG into a polymer composition affects the ease of processing of the polymer composition. Thus, in some embodiments, the invention relates to a method of mixing PEG-based PPA comprising melt blending a PEG composition and a polymer (e.g., a polyethylene polymer), such as in an extruder at an elevated temperature (e.g., 200 ℃ or higher). For example, such methods include melt blending and/or co-extruding PEG and polymer (and optionally other additives) in a compounding extruder (compound extruder), and pelletizing the mixture after it exits the extruder, thereby locking the homogeneously blended mixture in place.

Drawings

FIG. 1 is a schematic diagram conceptually showing stripes of melt fracture and zones where melt fracture is eliminated in a blown film during extrusion.

Fig. 2A is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to some of the experimental runs of the examples.

Fig. 2B is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to additional test runs of the examples.

Fig. 3A is a graph showing melt fracture elimination time versus load (ppm) for PEG-based PPA in relation to some of the examples.

Fig. 3B is a graph showing extruder die pressure versus load (ppm) for PEG-based PPA in relation to some of the examples.

Fig. 4A is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to some of the experimental runs of the examples.

Fig. 4B is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to additional test runs of the examples.

Fig. 4C is a graph showing the extent of melt fracture over time in blown films made using various PPAs in connection with yet further test runs of the examples.

Fig. 4D is a graph showing the extent of melt fracture over time in blown films made using various PPAs in connection with yet further test runs of the examples.

Fig. 4E is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to yet further test runs of the examples.

Fig. 5 is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to some of the experimental runs of the examples.

Fig. 6 is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to some of the experimental runs of the examples.

Fig. 7 is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to some of the experimental runs of the examples.

Fig. 8 is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to some of the experimental runs of the examples.

Fig. 9 is a graph showing the extent of melt fracture over time in blown films made using various PPAs in relation to some of the experimental runs of the examples.

Fig. 10A is a graph showing heat seal strength of some films made using various PPAs in relation to the examples.

Fig. 10B is a graph showing peak hot tack forces for some films made using various PPAs in connection with the examples.

Detailed Description

Definition of the definition

For purposes of this disclosure, various terms are defined below.

The term "polyethylene" refers to a polymer having at least 50wt% ethylene derived units, such as at least 70wt% ethylene derived units, such as at least 80wt% ethylene derived units, such as at least 90wt% ethylene derived units, or at least 95wt% ethylene derived units, or 100wt% ethylene derived units. Thus, the polyethylene may be a homopolymer or a copolymer, including a terpolymer, having one or more other monomer units. The polyethylenes described herein can, for example, comprise at least one or more other olefins and/or comonomers.

"Olefins", alternatively referred to as "olefins", are straight, branched, or cyclic compounds of carbon and hydrogen having at least one double bond. For the purposes of this specification and the appended claims, when a polymer or copolymer is referred to as comprising an olefin, the olefin present in such polymer or copolymer is the polymerized form of the olefin. For example, when a copolymer is said to have an "ethylene" content of 50wt% to 55wt%, it is understood that the monomer units (mer units) in the copolymer are derived from ethylene in the polymerization reaction, and that the derived units are present at 50wt% to 55wt% based on the weight of the copolymer. "Polymer" has two or more monomer units that are the same or different. "homopolymer" is a polymer having the same monomer units. A "copolymer" is a polymer having two or more monomer units that are different from each other. "terpolymer" is a polymer having three monomer units that differ from one another. Accordingly, as used herein, the definition of copolymer includes terpolymers, etc. As used herein to refer to monomer units, "different" indicates that the monomer units differ from each other by at least one atom or are isomerically different.

The term "alpha-olefin" refers to an olefin having a terminal carbon-carbon double bond in its structure R ¹R²C＝CH₂, where R ¹ and R ² can independently be hydrogen or any hydrocarbyl group; if R ¹ is hydrogen and R ² is alkyl. "Linear alpha-olefins" are alpha-olefins in which R ¹ is hydrogen and R ² is hydrogen or linear alkyl. For purposes of this disclosure, ethylene should be considered an alpha-olefin.

As used herein, the term "extrusion" and grammatical variations thereof is meant to include processes in which the polymer and/or polymer blend is formed into a melt, such as by heat and/or shear forces, and the melt is then forced out of the die in a form or shape, such as a film or in strands (which are pelletized). Most any type of equipment will be suitable for extrusion, such as single or twin screw extruders, or other melt blending devices as known in the art and may be equipped with a suitable die. It will also be appreciated that extrusion may be performed as part of the polymerization process (particularly in the finishing portion of such a process) as part of forming the polymer pellets; or it may be performed as part of a process of forming an article, such as a film, from polymer pellets (e.g., by at least partially melting the pellets and extruding through a die to form a sheet, particularly when combined with blowing air, as in a blown film forming process). In the context of the present disclosure, extrusion in the finishing portion of the polymerization process may be referred to as compounding extrusion, and typically includes feeding additives plus additive-free (reactor grade) polymer to an extruder; while extruding the polymer to make an article (e.g., extruding polymer pellets to make a film) is conceptually "downstream" (e.g., at a later point, after the polymer product has been formed, including by compounding extrusion), and typically includes feeding the optional additives plus the additive-containing polymer to an extruder.

Polymer

In various embodiments, the polymer composition comprises one or more polymers, preferably polyolefin polymers. Examples include homopolymers (e.g., homopolymers of C ₂ to C ₁₀ alpha-olefins, preferably C ₂ to C ₆ alpha-olefins). Specific examples of homopolymers include homo-polyethylene and polypropylene (hPP). In the case of homo-polyethylene, such polymers can be produced, for example, by free radical polymerization in a high pressure process, typically yielding a highly branched ethylene homopolymer-commonly referred to as LDPE (low density polyethylene), having a density of less than 0.945g/cm ³, typically 0.935g/cm ³ or less, such as in the range from 0.900, 0.905, or 0.910g/cm ³ to 0.920, 0.925, 0.927, 0.930, 0.935, or 0.945g/cm ³. All polymer density values are determined according to ASTM D1505 unless otherwise indicated herein. Samples were molded according to ASTM D4703-10a, procedure C, and conditioned for 40 hours according to ASTM D618-08 (23 ℃ + -2 ℃ and 50% + -10% relative humidity) prior to testing.

In another example, ethylene monomer may be polymerized via known gas phase, slurry phase, and/or solution phase polymerization (e.g., using a catalyst such as a chromium-based catalyst, or a single site catalyst such as a ziegler-natta and/or metallocene catalyst, all of which are well known in the polymerization art and are not further discussed herein). In the case of producing a more highly linear ethylene homopolymer (e.g., using gas phase or slurry phase polymerization, wherein any of the above-noted catalysts is used), the linear ethylene homopolymer may be referred to as HDPE (high density polyethylene), typically having a density of 0.945g/cm ³ or higher, such as in the range from 0.945 to 0.970g/cm ³.

Still further examples of polymers include copolymers of two or more C ₂ to C ₄₀ alpha-olefins, such as C ₂ to C ₂₀ alpha-olefins, such as ethylene-alpha-olefin copolymers, or propylene-alpha-olefin copolymers (e.g., propylene-ethylene copolymers, or propylene-ethylene-diene terpolymers, sometimes referred to as EPDM or PEDM). Specific examples contemplated herein include copolymers of ethylene and one or more C ₃ to C ₂₀ alpha-olefin comonomers, such as C ₄ to C ₁₂ alpha-olefin comonomers (in various embodiments, 1-butene, 1-hexene, 1-octene, or mixtures of two or more thereof are preferred). Ethylene copolymers (e.g., copolymers of ethylene and one or more C ₃ to C ₂₀ alpha-olefins) may comprise an amount of ethylene derived units of at least 80wt%, or 85wt%, such as at least 90wt%, 93wt%, 94wt%, 95wt%, or 96wt% (e.g., in the range from a low value of 80wt%, 85wt%, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, or 97wt% to a high value of 94wt%, 95wt%, 95.5wt%, 96wt%, 96.5wt%, 97.5wt%, or 98wt%, with the proviso that the high value is greater than the low value) of any of the foregoing low values being contemplated. For example, the ethylene copolymer may comprise 94wt% or 95wt% to 97wt% or 98wt% of ethylene derived units, based on the total amount of ethylene derived units and comonomer derived units. The remainder of the copolymer (based on ethylene derived units and comonomer derived units) is made up of comonomer derived units. For example, comonomer units (e.g., C ₂ to C ₂₀ α -olefin derived units, such as units derived from butene, hexene, and/or octene) may be present in the ethylene copolymer at a high value ranging from a low value of 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, or 6wt%, to a high value of 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 15wt%, or 20wt%, with the proviso that the high value is greater than the low value, of any of the foregoing low values being contemplated.

For ethylene-based, propylene-based, or other alpha-olefin-based copolymers, several suitable comonomers have been indicated, although in various embodiments other alpha-olefin comonomers are contemplated. For example, the alpha-olefin comonomer may be linear or branched, and two or more comonomers may be used if desired. Examples of suitable comonomers include linear C ₃-C₂₀ alpha-olefins (such as butene, hexene, octene as already noted), and alpha-olefins having one or more C ₁-C₃ alkyl branches or aryl groups. Examples may include propylene; 3-methyl-1-butene; 3, 3-dimethyl-1-butene; 1-pentene; 1-pentene having one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene having one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene having one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl substituted 1-decene; 1-dodecene; and styrene. It should be understood that the list of comonomers described above is merely exemplary and is not intended to be limiting. In some embodiments, the comonomer comprises propylene, 1-butene, 1-pentene, 4-methyl-l-pentene, 1-hexene, 1-octene, and styrene.

In particular embodiments, the polymer may comprise or may be an ethylene copolymer (according to those described above). The ethylene copolymer may be produced in a gas phase, slurry phase or solution phase polymerization, and some particularly preferred ethylene copolymers may be produced in a gas phase or slurry phase polymerization. A particular example is Linear Low Density Polyethylene (LLDPE), which is a copolymer of ethylene and one or more alpha-olefins polymerized in the presence of one or more single site catalysts, such as one or more ziegler-natta catalysts, one or more metallocene catalysts, and combinations thereof. The density of such LLDPE may range from a low value of 0.900, 0.905, 0.907, 0.910g/cm ³ to a high value of 0.920, 0.925, 0.930, 0.935, 0.940, or 0.945g/cm ³. LLDPE can differ from the LDPE mentioned above in several respects, many of which are well known in the art, including the degree of branching (sometimes more specifically referred to as long chain branching) in the produced polymer, noting that LLDPE has significantly less (if any, typically little) long chain branching. In particular embodiments, the polymer of the polymer composition is or includes a metallocene-catalyzed LLDPE (mLLDPE).

Furthermore, it may be particularly advantageous to configure PEG or PEG-based PPA in a polymer composition comprising one or more polymers (e.g., ethylene homopolymers or copolymers) having specific rheological properties. For example, according to some embodiments, the polymer (e.g., ethylene homo-or copolymer) of the polymer composition has an MI of 5.0g/10min or less, preferably 2.5g/10min or less, such as 1.0g/10min or less, or in the range from 0.1, 0.2, or 0.5g/10min to 1.0, 1.2, 1.5, 2.0, 2.5, 3.0, 4.0, or 5.0g/10min (where ranges from any low value to any high value are contemplated).

Melt Index Ratio (MIR) is another polymer property that may be of interest in this regard. MIR is defined herein as the ratio of High Load Melt Index (HLMI) (determined according to ASTM D1238 at 190 ℃, 21.6kg load) to melt index, or HLMI/MI. The polymer of some embodiments may have a MIR in the range from 10, 12, or 15 to 20, 25, or 30. In still other embodiments, the MIR may be greater than 30, such as in the range from 35 or 37 to 60, 65, 70, 75, 80, 85, 90, 95, or 100. More generally, polymers having MIR ranging from any of the foregoing low values to any of the foregoing high values (e.g., 10 to 65, such as 12 to 60) are contemplated in various embodiments.

Additionally or alternatively, in some embodiments, the density of the polymer may be in the range of from 0.905 to 0.945g/cm ³, such as in the range of from a low value of any of 0.905, 0.907, 0.908, 0.910, 0.911, 0.912, 0.913, 0.914, or 0.915g/cm ³ to a high value of any of 0.916, 0.917, 0.918, 0.919, 0.920, 0.924, 0.926, 0.930, 0.935, 0.940, or 0.945g/cm ³, where any of the foregoing low values to any of the foregoing high values (e.g., 0.910 to 0.925 or 0.935g/cm ³, such as 0.912 to 0.925g/cm ³, or 0.918g/cm ³) are contemplated herein. In yet other embodiments, the polymer may have a higher density (e.g., HDPE) with a density in the range of from 0.945g/cm ³ to 0.970g/cm ³.

PEG-based polymer processing aids

The polymer composition further comprises a PEG-based PPA; or in other words, the polymer composition may further comprise PEG.

It is noted that PEG is a component in some known fluoropolymer-based PPAs (see e.g. EP 3908627), and it has been proposed that higher molecular weight PEG (commonly referred to as polyethylene oxide or PEO, see below for more details) is among other PPAs one of the other ingredients (such as metal salts of specific acids or alkyl sulfates) (see e.g. EP 3234004). However, the inventors of the present invention found that certain lower molecular weight variants of polyethylene glycol can be used as PPA without other components, especially without fluorine-based components and/or inorganic components such as the aforementioned metal salts. Accordingly, PPA of the present disclosure comprises at least 80wt% peg, more preferably at least 90wt% peg, such as at least 95wt% or at least 99wt% peg; alternatively, PPA may be said to consist of or consist essentially of PEG (where "consisting essentially of … …" in this context means that no other components are intentionally included, but trace amounts, e.g., 100ppm or less, preferably 50ppm or less, or even 10 or 1ppm or less, of impurities are allowed). More generally, the inventors of the present invention have identified suitable processing conditions, suitable PEG variants (e.g., based on molecular weight), and suitable loadings of PEG-based PPA in polymer compositions, which conditions, alone or in combination, can overcome many of the challenges of incorporating PEG-based PPA into polymer compositions. For example, PEG has a significantly lower melting temperature than many polymers (e.g., polyethylene homopolymers or copolymers), and thus beading may begin during attempts to mix such ingredients with such polymers that have a higher melting point than PEG. This phenomenon may be reduced or exacerbated depending on the size (molecular weight) of the PEG and/or the desired loading of the PEG-based PPA in the polymer; and may affect proper mixing. Furthermore, as a general hydrophilic compound, PEG incorporation into a generally more hydrophobic polymer composition presents some challenges, requiring close examination of the proper molecular weight range, amount, and method of incorporating PEG-based PPA into the polymer composition, especially where the PEG-based PPA comprises a significant amount of PEG (80 wt% or more, 90wt% or more, 99wt% or more, or substantially all).

As used herein, polyethylene glycol or PEG refers to a polymer represented as H- (O-CH ₂-CH₂)_n -OH, where n represents the number of times the O-CH ₂-CH₂ (oxyethylene) moiety is repeated, n can be in a wide range, as PEG has a wide variety of molecular weights, e.g., for lower molecular weight polyethylene glycols (about 1500 g/mol), n can be about 33, for higher molecular weight polyethylene glycols (about 10,000 g/mol), ranging up to about 227, such as about 454 for about 20,000g/mol molecular weight PEG, and about 908 for about 40,000 molecular weight PEG, and n can be even higher for higher molecular weight PEG variants.

It should also be noted that PEG may be equivalently referred to as polyethylene oxide (PEO) or Polyoxyethylene (POE). Sometimes in industry terminology, PEG is a nomenclature for relatively lower molecular weight variants (e.g., molecular weight of 20,000g/mol or less), while polyethylene oxide or PEO is used for higher molecular weight variants (e.g., greater than 20,000 g/mol). However, for the purposes of the present application, references to polyethylene glycol or PEG should not be taken alone to imply a particular molecular weight range, unless the molecular weight range is explicitly stated. That is, the term polyethylene glycol or PEG may be used herein to refer to polymers having the structure H- (O-CH ₂-CH₂)_n -OH, where n is such that the molecular weight of the polymer is less than 20,000g/mol, and the term polyethylene glycol or PEG may also be used to refer to such polymers, where n is such that the molecular weight of the polymer is greater than 20,000g/mol, such as in the range from 20,000 to 40,000 g/mol.

As used herein, PEG "molecular weight" refers to weight average molecular weight (Mw) as determined by Gel Permeation Chromatography (GPC), and PEG "molecular weight distribution" or MWD refers to the ratio of Mw to number average molecular weight (Mn), i.e., mw/Mn. The most preferred PEG composition for PPA will have a narrow MWD, such as in the range from a low value of any of about 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5 to a high value of any of about 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, or 3.0, with the proviso that the high end value is greater than the low end value (e.g., 1.0 to 2.0, or 1.0 to 1.5, such as 1.0 to 1.2, or even 1.0 to 1.1) taking into account the range from any of the aforementioned low end values to any of the aforementioned high end values. Particularly preferred are PEG compositions having a MWD of about 1 to 1.1. However, obtaining such uniform length polymer chains (i.e., narrow MWD) can be expensive; more generally, commercially available PEG compositions may have a broader MWD value (e.g., ranging from 1 to 3, 4, 5, or even greater). Thus, such PEG compositions are also within the scope of the present invention. These PEG compositions can still be suitably used as PPA, potentially (but not necessarily) compensated for by increasing the PEG loading (e.g., 700-1400ppm compared to as low as 400-700ppm for PEG with a narrower MWD) for such wider MWD PEG. The PPA loading on PEG will be discussed in more detail below.

In embodiments employing narrow MWD PEG, the Mw value of the PEG will generally be relatively close (e.g., within +/-10%) to Mn; however, in any event, where there is a difference between the two (Mw and Mn), mw should be controlled as the preferred "molecular weight" measurement for purposes of this disclosure. It should also be noted that many commercial PEG compounds include nominal molecular weights (e.g., "PEG 3K" or "PEG 10K" indicate nominal molecular weights of 3,000g/mol and 10,000g/mol, respectively). Likewise, the Mw of the PEG should be controlled in preference to any inverse nominal index.

Polyethylene glycols suitable for use in the PEG-based PPA herein generally include PEG of various molecular weights, potentially including PEG having a Mw ranging from as low as 500g/mol up to 200,000g/mol, such as a Mw ranging from a low value of any of 500, 600, 700, 800, 900, 1000, 3000, 5000, 7000, or 7500g/mol to a high value of 40000, 50000, 60000, 75000, 80000, 90000, 100000, 125000, 150000, 175000, or 200000g/mol, where ranges from any low end value to any high end value are contemplated.

However, in certain embodiments, a particularly preferred PEG is one having a molecular weight of less than 40,000 g/mol; such as molecular weights ranging from a low value of any of 500、600、700、800、900、1000、1500、2000、2500、3000、3500、4000、4500、5000、5500、6000、7000、8000、8500、9000、9500、10000、12500、 and 15000g/mol to a high value of any of 7000、7500、8000、8500、9000、9500、10000、10500、11000、11500、12000、12500、15000、20000、22000、25000、30000、35000、39000、 and 39500g/mol, provided that the high value end is greater than the low value, and wherein ranges from any of the foregoing low end values to any of the foregoing high end values (e.g., 1,500 to 35,000g/mol, or 5,000 to 20,000g/mol, such as 5,000 to 12,000g/mol, or 6,000 to 12,000 g/mol) are generally contemplated. Specific higher or lower subranges may also be suitable (e.g., PEG with a Mw of 1,500 to 5,500g/mol, or PEG with a Mw of 5,000 to 12,000g/mol, or PEG with a Mw of 10,000 to 20,000g/mol, or PEG with a Mw of 15,000 to 25,000g/mol, or PEG with a Mw of 25,000 to 35,000 g/mol).

In addition, it is contemplated that blends of a plurality of the foregoing PEG compounds can form suitable PPAs. For example, the PEG-based PPA may comprise at least 90wt%, preferably at least 99wt%, of a blend of two or more polyethylene glycols, such as a blend of any two or more of: a first PEG having a molecular weight in the range of from 3,000 to 7,000 g/mol; a second PEG having a molecular weight in the range of from 5,000 to 12,000 g/mol; a third PEG having a molecular weight in the range of from 10,000 to 20,000 g/mol; and a fourth PEG having a molecular weight in the range of from 20,000 to 40,000g/mol, provided that the first, second, third, and fourth PEGs of such blends each have a molecular weight different from the other polyethylene glycol(s) of those blends. Also, in some embodiments, higher molecular weight PEG may be included in such blends (e.g., one or more PEG having a molecular weight greater than 40,000 g/mol).

However, as noted, it is contemplated that many embodiments of the PEG-based PPA as described herein do not include polyethylene glycol (or polyethylene oxide) having a molecular weight greater than 40,000 g/mol. That is, in such embodiments, all or substantially all of the polyethylene glycols of the polymer composition have a molecular weight of less than 40,000g/mol; such as less than 35,000g/mol, or less than 33,000g/mol, or less than 22,500g/mol, or less than 20,000g/mol, or less than 12,000g/mol, such as less than 10,000g/mol. In this context, "substantially all" means that a small amount (50 ppm or less, more preferably 10ppm or less, such as 1ppm or less) of higher molecular weight PEG can be included without losing the effect of including predominantly the lower molecular weight PEG described herein. It is believed that the interest in lower molecular weight PEG generally enables the reduction of the loading of PEG-based PPA to achieve the desired melt fracture elimination on most polymer grades that may experience melt fracture when forming blown films. Similarly, lower molecular weight PEG is believed to diffuse more rapidly to the surface of polymeric materials extruded in, for example, blown film processes than higher molecular weight PEG variants; thus, lower molecular weight PEG variants will typically result in faster elimination of melt fracture in the blown film (and thus reduce reject production). However, it is contemplated that higher molecular weight PEG (e.g., mw >40,000 g/mol) may be suitable for certain polymer grades in some cases; thus, it is contemplated that such higher molecular weight PEG may be included in polymer compositions that remain within the spirit and scope of some embodiments of the present invention.

Commercially available examples of suitable polyethylene glycols, particularly lower molecular weight polyethylene glycols, include those available from BASF corporation (BASF)E 1500；/>E 3400；/>E 4000；/>E 6000；/>E8000; and/>E9000 polyethylene glycol (wherein the numbers represent the nominal molecular weight of PEG); and also includes Carbowax ^TM8000、Carbowax^TMSentry^TM NF EP available from Dow corporation (Dow).

Measuring molecular weight moment

The distribution and moment of molecular weight was determined by using an Agilent1260INFINITY II Multi-Detector GPC/SEC system, equipped with multiple detectors connected in series, including a Differential Refractive Index (DRI) Detector, a viscometer Detector, a double angle Light Scattering (LS) Detector, and a UV diode array Detector, unless otherwise indicated. Two AGILENT PLGEL- μm hybrid-C columns plus guard columns were used to provide polymer separation. As mobile phase THF solvent or equivalent from Sigma-Aldrich (Sigma-Aldrich) with 250ppm of the antioxidant Butylated Hydroxytoluene (BHT) was used. The nominal flow rate was 1.0ml/min and the nominal sample volume was 25 μl. The entire system, including column, detector and tube, was operated at 40 ℃. Column calibration was performed using twenty-three narrow polystyrene standards ranging from 200 to 4,000,000 g/mol.

The data from any combination of DRI, light scattering and viscometer detectors are processed using Agilent Multi-Detector GPC data analysis software to obtain information about polymer properties. Here, the light scattering MW is calculated by combining the concentration measured by DRI and the Rayleigh ratio measured by LS in each elution volume slice plus a detector calibration constant and a polymer parameter, such as refractive index delta (dn/dc). For the poly (ethylene glycol) samples used in this patent, dn/dc was determined to be about 0.07ml/g in THF solvent.

Amount and polymer characteristics of PEG-based PPA

The polyethylene glycol (or PEG-based PPA) may be disposed in the polymer composition in an amount of at least 200ppm, such as at least 250ppm, at least 300ppm, at least 400ppm, at least 500ppm, or at least 600 ppm. For example, the amount may be configured in a range from a low value of any of 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 900, 950, 1000, 1100, 1200, 1250, and 1500ppm to a high value of any of 400、500、600、700、800、900、1000、1100、1200、1300、1400、1500、1600、1700、1800、1900、2000、2500、3000、3500、4000、4500、5000、7500、10000、12500、 and 15000ppm, with the proviso that the high end value is greater than the low end value (e.g., 300 to 15,000ppm, such as 300 to 2,000ppm, or 500 to 1500ppm, such as 500 to 1200ppm, or 600 to 1200 ppm) taking into account the range from any of the aforementioned low values to any of the aforementioned high values. ppm values may be applicable to polyethylene glycol included in the polymer composition; or in various embodiments, a PEG-based PPA suitable for inclusion in a polymer composition. Furthermore, unless specifically indicated otherwise, the ppm values recited herein for polyethylene glycol (or PEG-based PPA) and any other additives described herein are based on the mass of the polymer composition (i.e., comprising the polymer plus PPA and any and all other additives in the polymer composition). The amount of PPA in the polymer composition can most easily be determined using the mass balance principle (e.g., PPA amount is determined as the mass of PPA added to the polymer composition divided by the mass of PPA blended together to form the polymer composition plus the mass of polymer plus any other additives). NMR analysis can be used to determine the PPA content of an already mixed polymer composition, e.g. polymer pellet(s) comprising polymer and PPA, but in case of a difference between the two methods (mass balance and NMR), a mass balance method should be used.

Furthermore, the inventors of the present invention have unexpectedly found that PEG molecular weight can affect optimal loading. In particular, higher molecular weight PEG eliminates melt fracture faster at lower loadings than lower molecular weight PEG; and at the same time, higher loadings of higher molecular weight PEG may actually result in slower melt fracture elimination in films made with polymer compositions comprising PEG-based PPA. On the other hand, significantly lower molecular weight PEG variants may require higher loadings, while lower loadings of these PEG variants may take too long to eliminate melt fracture (or not eliminate melt fracture completely). The demarcation line between these opposite trends appears to occur somewhere in the molecular weight range of 7,500-11,000g/mol, with the 7,500-11,000g/mol region representing a transition zone where neither trend is overly pronounced. Thus, it is generally preferred to have PEG with a Mw of less than 7,500g/mol employed at higher loadings (e.g., 1000, 1100, or 1200ppm to 2000ppm or more), while PEG with a Mw of 11,000g/mol or more is better employed at medium or low loadings (e.g., 200-500, 600, 700, 800, 900, or 1000 ppm). However, the situation is somewhat more complicated, so the solution is not necessarily to simply prioritize the higher molecular weight PEG. In particular, as described herein, certain grades of polymers may require higher loadings of PEG (regardless of molecular weight) because polymer rheology also affects the performance of PEG in eliminating melt fracture of blown films made from the polymer. Thus, the use of higher molecular weight PEG may lead to the disadvantage of varying grade-specific loading, wherein accidental loading of too much PEG may adversely affect performance in some cases, and may improve performance in other cases.

These trends are generally applied, first see a set of embodiments that employ lower molecular weight PEG in combination with relatively higher loading levels. That is, the polymer composition of some embodiments comprises PEG (or PPA based on PEG), wherein the PEG(s) of the polymer composition have a Mw of less than 7,500g/mol (e.g., in the range from 95g/mol to less than 8,000g/mol, such as from 95, 100, 500, or 600g/mol to 1000, 3000, 4000, 5000, 6000, 7000, or 7250 g/mol); and further wherein the total amount of PEG in the polymer composition ranges from a low value of any of 800, 850, 900, 950, or 1000ppm to a high value of any of 1200, 1250, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, or 5000ppm, wherein ranges from any of the foregoing low end values to any of the foregoing high end values (e.g., 800 or 900ppm to 2000ppm, such as 950ppm to 1700ppm or 1000ppm to 1500 ppm) are also contemplated.

Second, see a set of embodiments that employ relatively higher molecular weight PEG in combination with relatively lower loading levels. That is, the polymer composition may comprise PEG (or PEG-based PPA), wherein the PEG(s) of the polymer composition have a Mw of greater than 11,000g/mol (e.g., in the range from greater than 11,000g/mol to 35,000 or 40,000g/mol, such as from a low end value of any of >11000, 11500, 12000, 12500, or 14000 to a high end value of any of 15000, 16000, 17500, 20000, 25000, 30000, 35000, or 40000 g/mol); and further wherein the total amount of PEG in the polymer composition ranges from a low value of any of 200, 250, or 300ppm to a high value of 300, 350, 400, 425, 450, 500, 600, 700, 750, 800, 1000, or 1100 ppm. Thus, specific examples are shown wherein the PEG(s) of the polymer composition have a Mw in the range from 11000 to 20000g/mol and the total amount of PEG in the polymer composition is in the range from 200 to 800 ppm.

Furthermore, as noted, the preferred range of PEG loading may further need to be tailored based on the characteristics of the polymer into which the PEG-based PPA is configured, and in particular the rheological characteristics of the polymer. For example, polymers with lower MI and/or higher MIR (e.g., metallocene-catalyzed linear low density ethylene copolymers) may require higher loadings of PEG-even the higher Mw PEG variants just discussed. For example, in the case of MI less than 0.45g/10min (190 ℃,2.18 kg) (and optionally further in the case of MIR greater than 30), even for higher Mw PEG variants, a loading of 700ppm or higher, even up to 1000 or 1100ppm, may be required.

Given the diminishing potential benefits of encountering melt fracture elimination at higher PEG loadings for higher Mw PEG variants in some polymers, while other polymers (e.g., low MI variants) require higher PEG loadings, some embodiments herein emphasize simplicity, particularly by targeting PEGs with Mw in the mid-range of the phenomenon observed above (e.g., mw in the range from 7500 to 11000g/mol, such as from 7500 to 9000g/mol or from 9000 to 11000 g/mol). This enables robust tailoring of PEG loading for polymers while avoiding the concern of significant loss of performance when turning to higher loadings, as sometimes observed with higher molecular weight PEG; for example, for polymers having MI less than 0.45g/10min (190 ℃,2.18 kg) (and optionally further having MIR greater than 30), the PEG-based PPA may be configured such that the PEG(s) of the PEG-based PPA have a Mw in the range from 7500 to 9000 or 11000 g/mol; and is present in the polymer composition in a range from 700ppm, 800ppm, or 900ppm to 1100 ppm. And for polymers that allow lower loading of PEG (e.g., MI greater than or equal to 0.45g/10min (190 ℃,2.18 kg)), having PEG(s) such that the Mw of the PEG(s) is in the range of from 7500 to 9000 or 11000g/mol will allow lower loading (e.g., 200 or 250ppm to 400, 500, or 600ppm of PEG in the polymer composition).

Similar benefits of simplicity can be obtained using lower Mw PEG variants of some of the above-mentioned embodiments (that is, increased loadings tend to result in improved performance without having to strictly consider polymer rheology). Also, while the higher Mw PEG variants of the other embodiments mentioned above may introduce some additional complexity in balancing polymer rheology, they still bring their own significant benefits in the form of generally lower required loadings. Thus, the present disclosure generally encompasses all of these classes of PEG, as well as their different benefits; the skilled artisan having the benefit of this disclosure will be able to readily select the most appropriate PEG variants from these PEGs for a given desired PPA.

Method of incorporating PEG-based PPA into a polymer composition

The method according to various embodiments includes adding polyethylene glycol and/or PEG-based PPA (according to the description above) to the polymer product (e.g., polymer pellets and/or slurry) exiting the polymerization reactor to form a pre-finished polymer mixture in or upstream of the compounding extruder. Thus, the pre-finished polymer mixture comprises the polymer and the PEG-based PPA (all according to the respective description above), as well as any optional other additives (which may be provided to the mixture with, before or after the PEG-based PPA). The pre-finished polymer mixture may be, for example, a polymer melt (e.g., formed in or just upstream of a compounding extruder). The mixture is then extruded and optionally pelletized to form an additional polymer composition (e.g., polymer pellets) comprising the PEG-based PPA and the polymer (each according to the above, and the amount of PEG or PEG-based PPA is consistent with the discussion above), and any optional other additive(s).

Additionally or alternatively, the method can include mixing the finished polymer (e.g., polymer pellets) with PEG or PEG-based PPA to form a polymer article mixture; and processing the polymer article mixture to form a film. Such processing may be according to methods well known in the art, and in particular according to blown film extrusion.

Returning to embodiments involving compounding extrusion (e.g., as part of a finishing process to produce a polymer composition), methods according to the present disclosure may be employed to schedule appropriate PEG dosing for different polymer grades (e.g., as may be produced as part of a polymer production campaign).

Such methods may include: obtaining a first polymer reactor product from a polymerization reactor at a first time, the polymer reactor product having a first MIR and a first MI; mixing a first portion of the PEG-based PPA with a first polymer reactor product at a first PEG amount (the PEG-based PPA such that PEG(s) in the PPA have a Mw in the range of from 7500 to 11000 g/mol) to form a first pre-finished polymer mixture; and extruding and optionally granulating the first pre-finished polymer mixture, thereby obtaining a first product (e.g., first polymer pellets) comprising the first finished polymer. Further, at a second time after the first time, obtaining a second polymer reactor product from the polymerization reactor having a second MI lower than the first MI (optionally, additionally or alternatively having a MIR greater than the first MIR); and mixing a second portion of the PEG-based PPA with a second polymer reactor product in a second amount of PEG that is greater than the first amount of PEG. This forms a second pre-finished polymer mixture, which is extruded and optionally pelletized to form a second product (e.g., second polymer pellets) comprising a second finished polymer.

In the methods of such embodiments, either or both of the first pre-finished polymer mixture and the first finished polymer product may be consistent with the polymer compositions (including polymers and PEG-based PPAs) discussed herein. Likewise, either or both of the second pre-finished polymer mixture and the second finished polymer product may also be consistent with the polymer compositions discussed herein. In particular, the polymers may be consistent with those discussed above, such as ethylene homopolymers or copolymers.

In particular embodiments, the first polymer reactor product has an MI of greater than 0.45g/10min and the second polymer reactor product has an MI of less than 0.45g/10 min. Optionally, the first polymer reactor product may have a MIR of less than 45; and the second polymer reactor product may have a MIR of greater than 45. Further, the first PEG amount may range from 200, 300, or 400ppm to 500, 600, 700, or 750 ppm; and the second PEG amount may be in the range from 1000ppm to 3000ppm, such as from 1000, 1100, or 1200 to 1600, 1800, 2000, 2500, or 3000 ppm.

The above-described methods and any other method of mixing PEG (or PEG-based PPA) with a polymer to form a polymer composition as described herein further comprise thoroughly mixing PEG into the polymer. The inventors of the present invention unexpectedly found that not all methods of mixing PEG are sufficient; alternatively, the PEG (or PEG-based PPA) should be melt blended with the polymer at a sufficiently high temperature and/or specific energy input (the total mechanical energy forced into the polymer per unit weight, e.g., J/g, a measure of the degree of mixing) to achieve adequate homogenization between the PEG and the polymer. For example, melt blending can achieve adequate homogenization, such as by melting at elevated temperatures (e.g., 150 ℃ or higher, such as 200 ℃ or higher) and then coextruding PEG and polymer (e.g., in a compounding extruder), while simply melting PEG and tumble blending with polymer cannot achieve adequate homogenization. Thus, the methods of the various embodiments include mixing the two components in a manner that ensures that the PEG and polymer (e.g., polyethylene) melt during mixing (e.g., melt mixing in a compounding extruder, coextrusion). A preferred method according to some embodiments includes melt blending and co-extruding the PEG and polymer (and optionally other additives) in a compounding extruder, and pelletizing the mixture after it exits the extruder, thereby locking the homogeneously blended mixture in place. More specifically, such methods may include: (a) Feeding a PEG composition and a polymer (e.g., polyethylene), optionally with other additives, into an extruder; (b) Co-extruding the PEG composition and polymer in an extruder at a high temperature (e.g., 200 ℃ or higher) suitable for melting both the PEG and polymer; and (c) granulating the extrudate to form a polymer composition comprising the PEG-based PPA. Preferably, the extrusion is performed under an oxygen-deficient atmosphere (e.g., a nitrogen atmosphere).

Other additives

As noted, other additives (e.g., antioxidants, stabilizers such as UV stabilizers, catalyst neutralizers, and other additives known in the polymerization arts) may also optionally be present in the polymer composition. Where such additives are employed, they are also preferably free or substantially free of fluorine. Furthermore, reiterating that in the presence of other additives, the mass of such additives is included in the denominator used to determine the ppm loading of PEG-based PPA described herein (that is, the ppm loading is based on the total mass of polymer + PPA + other additives).

According to various embodiments, it may be advantageous to employ an additive package comprising an antiblocking agent and/or slip agent, possibly together with other additives. In particular, with respect to antiblocking agents and slip agents, the data indicate that these can provide the potential advantage of faster elimination of melt fracture when employed with PEG-based PPA. Examples of antiblocking agents are well known in the art and include talc, crystalline and amorphous silica, nepheline syenite, diatomaceous earth, clays, or various other antiblocking minerals. Specific examples include Optibloc reagent available from mining technologies company (Mineral Technologies). Examples of slip agents for polyolefins include amides such as erucamide and other primary fatty amides such as oleamide; and further includes certain types of secondary (bis) fatty amides. The antiblocking agent loading is typically about 500 to 6000ppm, such as 1000 to 5000ppm; slip agent loadings are typically 200 to 1000, 2000, or 3000ppm. Others may include, for example: a filler; antioxidants (e.g., hindered phenols such as IRGANOX ^TM additives available from baba-jiiy corporation (Ciba-Geigy); phosphites (e.g., IRGAFOS ^TM compounds available from baba-jia base); an anti-blocking (anti-blocking) additive; tackifiers such as polybutenes, terpene resins, aliphatic and aromatic hydrocarbon resins, alkali metal and glycerol stearates, and hydrogenated rosins; a UV stabilizer; a heat stabilizer; a release agent; an antistatic agent; a pigment; a colorant; a dye; a wax; silicon dioxide; a filler; talc; mixtures thereof, and the like.

Film and method for producing the same

As noted, an important reason for using PPA is to eliminate melt fracture in blown films. Ideally, when replacing an existing PPA with a PEG-based PPA of the present disclosure, films made from polymer compositions comprising such PEG-based PPA will exhibit similar or superior properties compared to films made using polymer compositions comprising conventional PPA.

Accordingly, the invention of the present disclosure may also be embodied in films made from any of the above-described polymer compositions (and in particular polyethylene compositions) comprising a polymer and from 250 to 15000ppm (e.g., from 250 to 11000 ppm) of PEG-based PPA (e.g., such that the Mw of PEG(s) in PPA is less than 40,000g/mol, such as in the range from 3000, 4000, 5000, 6000, or 7500g/mol to 11000, 15000, 20000, or 35000 g/mol), and preferably substantially free of fluorine; wherein the film has one or more (and preferably all) of the following:

The 1% secant Modulus (MD) is within +/-5% psi, preferably within +/-1% psi, of the value (psi) of an otherwise identical film made using fluoropolymer-based PPA instead of PEG-based PPA;

Elmendorf tear (Elmendorf tear) (MD) is within +/-10% g, preferably within +/-5% g, of the value (g) of an otherwise identical film made using fluoropolymer-based PPA instead of PEG-based PPA;

Total haze is within +/-25%, preferably within +/-10%, and/or total haze is less than 6% of the value (in%) of an otherwise identical film made using fluoropolymer-based PPA instead of PEG-based PPA;

gloss (MD) within +/-12%, preferably within +/-10% of the value (in GU) of a film made using fluoropolymer-based PPA instead of PEG-based PPA, but otherwise identical; and

Dart (Dart) is within +/-1%, preferably within +/-0.5% or even within +/-0.1% of the value (g) of a film made using fluoropolymer-based PPA instead of PEG-based PPA, but otherwise identical.

In the discussion above, "made using a fluoropolymer-based PPA rather than a PEG-based PPA but otherwise identical" film is intended to mean that a film made using an effective amount of a PEG-based PPA is compared to a film made using an effective amount of a fluoropolymer-based PPA; the same amount of each PPA need not be used. An effective amount is an amount that results in the elimination of visible melt fracture from the film, consistent with the discussion regarding example 1.

Examples

In order to facilitate a better understanding of embodiments of the present invention, the following examples of preferred or representative embodiments are presented.

Blown film tests were performed on two blown film extruder lines L1 and L2 to demonstrate the general use of PPA formulations of the present invention. Both lines were operated using a single film annular die with the following conditions: the blow-up ratio was 2.5, the die temperature set point was 390°f, the film thickness was 3 mils, the die gap was 30 mils, and the frost line height was about 5 times the die diameter. L1 has a die diameter of 160mm, while L2 has a die diameter of 51 mm.

Example 1

Initially, in preparation for testing on line L1, the L1 film line extruder was fed with the prior polyethylene andThe blend of KC 30 (polyethylene-based cleaning and cleansing compound from schulman, inc.) was continued for at least 30 minutes at a 2:1 weight ratio (previous PE: KC 30 cleaning compound). The purpose of this initial step is to remove contaminants and potentially PPA from the metal surfaces inside the extruder and die. For all examples, the prior polyethylene used in this step was a PPA-free version of the same polyethylene used in connection with PPA as studied herein. In all runs related to this example 1, the mLLDPE used was an Exceed ^TM 1018 polyethylene, an ethylene-hexene copolymer available from Exxon Mobil chemical company (ExxonMobil Chemical Company), having a density of 0.918g/cm ³, a MI of 1.0g/10min, and a MIR of 16.

Second, the film line is stopped and the inner die is manually polished to remove KC 30 material.

Third, reinserted into the inner die and the line was resumed with the same pure feed of the previous mLLDPE material for 1 hour until the residual KC 30 was removed and melt fracture formed on the entire film surface made from mLLDPE. Fourth, conventional fluoropolymer-containing PPA (DYNAMAR ^TM FX 5929M) was fed into the extruder at a constant mass flow rate that matched that of mLLDPE. As PPA is fed, melt fracture slowly begins to disappear as a streak, as shown in fig. 1. Referring to fig. 1, as PPA is added, a melt fracture-free condition begins to occur as a band 101 in the machine direction 110 of the film 100 (i.e., the direction in which the film is extruded and blown). Fig. 1 is a schematic diagram conceptually showing this brief period of a stripe 105 of melt fractured film material and a stripe 101 without melt fractured film. Over time, the width of these strips 101 increases and the melt fracture zone decreases and eventually completely eliminates. This test using the indicated mLLDPE and conventional PPA is denoted C1 in table 1 below. Table 1 summarizes PPA and mLLDPE used in each test (with PPA-free versions of mLLDPE used in each case as the previous material, as outlined above), further noting that the output of all test films normalized to the annular die circumference (lbs/hr.—in die) remained within +/-30% of each other.

This procedure was repeated for test run I23, which was performed in the same manner as described above for test run C1, and used the same mLLDPE, except that instead of the conventional PPA used in test run C1, the PEG-based PPA of the present invention was used in the amounts indicated in table 1 (in this case,E8000, commonly labeled PEG 8K). And the process was repeated again for test runs I25 and I26, all on line L1 as indicated in table 1 below, as also indicated in table 1, with the amount of PEG 8K being incremented. This sequence was repeated on line L2 for test run C2 (conventional PPA) and inventive runs I27-I30, also indicated in Table 1 below. Table 1 further indicates the results of each test run: melt fracture (percent of film area) at 100min and melt fracture elimination time (in min), although the faster the time the better.

TABLE 1 inventive and comparative examples (PEG 8K) on lines L1 and L2 of example 1

For each experimental run, the time at which the PPA feed was started was recorded as time t=0, and the degree of melt fracture on each extruded film was observed as a percentage of the surface area of the film comprising melt fracture streaks (see fig. 1 and discussion above) relative to the duration of the PPA feed.

Fig. 2A and 2B are each a graph showing the degree of melt fracture (starting at 100% and ideally progressing to 0%) over time (i.e., over time after recovering PPA feed to the extruder) after time t=0 for the example 1 test associated with lines L1 and L2, respectively. In this way, the effectiveness of PPA in eliminating melt fracture in the resulting blown film can be judged. As can be seen from fig. 2A and 2B, on the L1 line, I26 and I25 (with 750ppm and 1000ppm PEG 8k, respectively) are advantageous compared to melt fracture elimination achieved with conventional PPA. Note also that C1 does not start at 100% melt fracture, as seen in fig. 2A; this is due to the shortage of material during operation of this embodiment, such that complete melt fracture cannot be formed. It is expected that this biases the results towards C1, if any, meaning that at higher loadings (e.g., 1000 ppm), PEG 8K can be expected to match the performance of existing PPA used in C1.

Surprisingly, at these same loadings (see I28, I29 and I30, 500, 750 and 1000ppm PEG 8K, respectively) on the L2 line, PEG 8K was actually superior to conventional PPA. Given that this may be due in part to the faster diffusivity of PEG 8K compared to conventional PPA, there is a more pronounced effect on the rate of melt fracture reduction when extruding at lower output ratios.

Example 2

To test whether PEG can have different PPA characteristics at different molecular weights, melt fracture elimination was characterized on compounding extruder line L2 (see description in example 1) (not only using commercial PEG 8K as PPA, but also using narrow dispersed PEG compositions of different molecular weights obtained from millbox Sigma (Millipore-Sigma)). The molecular weight distribution of each PEG composition was measured by gel permeation chromatography and is summarized in table 2. Non-commercial samples are in fact narrowly distributed, allowing a clear molecular weight trend to be discerned. The two shorter chains nominally labeled PEG 1.5K and PEG 3K were measured to be instead about 100 and 600. These measurements may be closer to the true value, but in any event the order of the five samples is preserved, so the overall conclusion is not affected by this difference. In addition, the same mLLDPE (ex ^TM 1018 ethylene-hexene copolymer) as in example 1 was also used in the operation of these example 2.

Table 2 number average molecular weight (Mn) and weight average molecular weight (Mw) of each PEG sample by gel permeation chromatography.

Table 3 summarizes the performance of the various PEG-based PPAs (note, each labeled according to their nominal molecular weight) at different loadings, as indicated in table 3 for each of the test runs listed. The output rates (lbs/hr-in die) are again within +/-30% of each other.

Table 3. Inventive and comparative examples of PEG of various molecular weights on L2.

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The data of Table 3, taken in combination with the data of Table 1 of example 1, demonstrates the sensitivity of melt fracture elimination to the molecular weight of the PEG employed. This is more clearly shown in fig. 3A, which shows the melt fracture elimination time versus load level for the different molecular weight PEG studied in examples 1 and 2. It appears that for low molecular weight PEG, the melt fracture elimination time decreases with load level, but for high molecular weight PEG this time increases instead generally with load level (and for PEG 20k, for a test duration of 100min, complete melt fracture elimination is not actually achieved at 600ppm and 1000ppm load, while elimination is achieved rapidly at only 300ppm load). Intermediate molecular weights (e.g., PEG 8K, reference example 1, and PEG 10K) with Mw 7500 to 11000 appear to be consistent across the widest load range.

Referring also to fig. 3B, the extruder pressure versus PEG loading is shown for the same PEG studied in examples 1 and 2. Extruder pressure also tended to drop with load levels, although commercial PEG 8K (see back table 1) followed this trend up to 750ppm load, while 1000ppm load returned to higher pressure, indicating that higher PEG loads in this intermediate molecular weight range may have some adverse effects; fortunately, for this particular PEG variant, the advantages of simplicity are maintained, since the 750ppm loading always eliminates melt fracture (meaning that it is not necessary to accept the disadvantage of higher extruder pressures at say 1000ppm loading, since 750ppm achieves the desired result).

In addition to table 3, the effect of the loading level of each PEG on melt fracture elimination time was readily seen in fig. 4A, 4B, 4C, 4D, and 4E, each of which shows the degree of melt fracture (%) as a function of time after time t=0 (i.e., as a function of time after PPA feed was restored to the extruder) for the corresponding PEG 1.5K, 3K, 10K, 20K, and 35K from table 3.

Example 3

Examples 1 and 2 discuss melt fracture elimination in blown films made from a single test PE resin (noted ex ^TM 1018 ethylene-hexene copolymer mLLDPE, available from exxon mobil chemical company). Example 3 the effect of different polyethylene resin properties on melt fracture elimination when using PEG 8K as PPA was investigated, and the effect of slip additive and antiblocking additive together with PPA on melt fracture elimination was also investigated. The resin and additive packages studied in connection with this example are summarized in table 4 below (where MI, density and MIR are each determined according to the methods already described herein). Each polyethylene in table 4 is a metallocene-catalyzed LLDPE which is a copolymer of ethylene and hexene, with the additional characteristics indicated below. It is further noted that the PEs used in examples 1 and 2 are also included in table 4 for ease of reference. All example 3 runs were performed on compounding extruder line L2 as described in example 1, using the polyethylene and additive package of table 4 instead of the polyethylene used in example 1. For each set of tests in each of the following corresponding tables 5-9, the output rates (lbs/hr-in. Die) were again within +/-30% of each other.

Table 4. PE grades used in the order of example ID.

Fig. 5 and table 5 below show the results of melt fracture elimination in blown films made with PE 3-1 using different loading levels of PEG 8K on line L2. These data demonstrate how PEG 8K is comparable to the reference PPA when using the slip/antiblock additive package. Here, the reference PPA is faster than the form considered in example 1C 2 without slip agent/antiblocking agent. Similarly, the 250ppm PEG 8K loading level of I32 was faster than the form of example 1 without slip agent/antiblocking agent in I27.

Table 5 PPA performance on L2 for PE 3-1 (Linear, 0.918g/cc density, 1MI,16MIR, metallocene PE with antiblocking/slip agent).

Fig. 6 and table 6 below show the results of melt fracture elimination in blown films made with PE 3-2 using different loading levels of PEG 8K on line L2. These data demonstrate how PEG 8K can eliminate melt fracture significantly faster for different resins and appears more sensitive than the reference PPA. It appears that the additive will respond according to the rheological properties of the resin. In the case of such resins, their high MI makes them less prone to melt fracture; it is possible that this allows PEG 8K to eliminate melt fracture more quickly.

Table 6 PPA performance on L2 for PE 3-2 (slightly branched, 0.923g/cc density, 0.48MI,40MIR, metallocene PE with antiblocking/slip agent).

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Fig. 7 and table 7 below show the results of melt fracture elimination in blown films made with PE 3-3 using different loading of PEG 8K on line L2. Perhaps due to the low MI of the resin, both reference PPA and PEG 8K eliminate melt fracture more slowly than in the previous grades, leaving behind thin strips of melt fracture that last for a long period of time. However, for PEG 8K, higher loading levels would satisfactorily reduce this elimination time. Notably, the presence of medium long chain branching in PE 3-3 and the lack of slip/antiblocking agents may also account for this slower melt fracture elimination.

Table 7 PPA performance on L2 for PE 3-3 (slightly branched, 0.938g/cc density, 0.28MI,58MIR, metallocene PE without antiblocking-slip agent).

Fig. 8 and table 8 below show the results of melt fracture elimination in blown films made with PE 3-4 using different loading of PEG 8K on line L2. Although the reference PPA exhibited an initially faster response, it eventually did not completely clear the melt fracture, which was done with PEG 8K at compositions as low as 750 ppm.

Table 8 PPA performance on L2 for PE 3-4 (Linear, 0.915g/cc density, 0.48MI,30MIR, metallocene PE with antiblocking/slip agent).

Fig. 9 and table 9 below show the results of melt fracture elimination in blown films made with PE 3-5 using different loading levels of PEG 8K on line L2. In this case, PEG 8K is superior to the reference PPA based on melt fracture elimination. Furthermore, it is useful to compare fig. 8 and 9, since the same PE is used in both, except that fig. 8 is for the resin with anti-blocking/slip additives (PE 3-4), and fig. 9 is for the resin without those additives (PE 3-5). This reveals that melt fracture elimination generally occurs faster for such resins without slip and antiblocking agents. However, for the case of comparing the PE resin via example 1 of fig. 2A (without slip agent/anti-blocking agent) with the same PE resin via fig. 5 (PE 3-1 of example 3) with slip agent/anti-blocking agent, the opposite trend is seen: slip/antiblock agents result in faster melt fracture elimination than the absence of slip/antiblock agents. This difference suggests a potential resin dependence on the impact of the slip agent and/or anti-blocking agent on PPA performance.

Table 9 PPA performance on L2 for PE 3-5 (Linear, 0.915g/cc density, 0.48MI,30MIR, metallocene PE without antiblocking-slip agent).

Example 4

Two different methods of mixing PEG 8K with polyethylene (specifically, PE 3-2 as outlined with respect to example 3) were investigated. In process I, PE pellets were tumble blended in a tumbler for 30 minutes, wherein the following were mixed: primary and secondary antioxidants, antiblocking and slip agents, and PEG 8K (which have been preheated to ensure the initial molten state of PEG 8K prior to being dispersed on the pellets during tumbling blending). The blend was then extruded through a compounding extruder under nitrogen at a melt temperature of about 450°f (about 232.2 ℃) and pelletized after exiting the extruder. The pellets are then fed into a blown film line extruder L2 for film conversion.

In contrast, method II skips the compounding extrusion step; and the blend was fed into a blown film line extruder L2 for film conversion within 12 hours of tumble blending.

Method I was used for all of the test runs previously discussed, including for PE 3-2 in test runs I37 and I39 (see example 3 and Table 6). Method II was used for the same PE 3-2 in test runs I40 and I41. Extrusion results at different PEG 8K loadings for both methods are reported in table 10 below.

Table 10. Comparative mixing methods I and II for PE 3-2 (slightly branched, 0.923g/cc density, 0.48MI,40MIR, metallocene PE with antiblocking/slip agent) on L2.

Using method II, the primary slip occurs between the molten mixture and the screw such that the output rate (lbs/hr-in. Die) observed for method II is 10% -20% of the rate observed for method I. Further increases in screw speed did not significantly improve throughput. Slightly branched resins of 0.48MI, 40MIR are resins that are easier to process among those selected, as evidenced by their low extrusion pressure and melt fracture propensity. Even so, PEG slides extensively when tumble blended alone. It is possible that without proper homogenization, the molten PEG beads up in the extruder barrel and forms a macroscopically lubricated interface, which interferes with mixing. This problem was never observed for any of the formulations mixed by method I, where PEG was more uniformly dispersed on each PE pellet.

Example 5

It is desirable to at least preserve membrane properties, if not improve them, by replacing PPA with commercial PPA with PEG-based PPA. PPA can in principle affect surface-sensitive properties, as it is believed to migrate to the surface of the molten film in order to mitigate melt fracture. In this example, a blown film line L1 was used to produce 1 mil thick films from test runs C1, I25 and I26 (all using an extruded ^TM mLLDPE having a density of 0.918g/cc, a MI of 1.0dg/min and a 16 MIR). The processing conditions were the same as described with respect to example 1, but the film thickness was made 1 mil by increasing the nip roll line speed. The results in table 11 below generally show that the film properties are similar whether the reference PPA or PEG 8K is used, indicating that the surface properties of the film are not significantly changed. There is a potential tradeoff: in the case of PEG, the film appeared to have slightly lower gloss and higher puncture break energy. This implies small changes in the surface (which do not significantly affect most properties).

Similarly, fig. 10A and 10B show very similar heat seal and heat tack peak force curves in the films of test runs C1, I25 and I26.

Table 11. Film properties of linear metallocene PE with various PPA formulations, 0.918g/cc density, 1dg/min MI, 16 MIR.

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Example 6

Nuclear Magnetic Resonance (NMR) methods were developed to analytically quantify PEG content. A substantial agreement was found between the two, although the PEG content of any given sample prior to blending, as measured by weighing, was up to 20% different from the PEG content as measured by NMR. In this report, the weighing value was taken as the default method, as there was no indication that there was a systematic deviation in the value between the two methods. Table 12 reports some sample measurements by NMR compared to mass balance (or weight) for test runs I51, I52 and I53.

Table 12. PEG content by both methods was compared.

Test method

Table 13 below reports the test methods used with respect to the examples. These methods are also used to determine characteristics according to embodiments described herein, unless otherwise specified in the description of the given characteristics.

Table 13. Measurement method.

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For brevity, only certain ranges are explicitly disclosed herein. However, any lower limit may be combined with any upper limit to list a range not explicitly recited, and any lower limit may be combined with any other lower limit to list a range not explicitly recited, as well as any upper limit may be combined with any other upper limit to list a range not explicitly recited in this manner. In addition, each point or individual value between its endpoints is included within the range even though not explicitly recited. Thus, each point or individual value may be combined with any other point or individual value or any other lower or upper limit as its own lower or upper limit to enumerate ranges not explicitly recited.

All documents described herein are incorporated by reference herein, including any priority documents and or test procedures that are not inconsistent with this document. As is apparent from the foregoing general description and the specific embodiments, while forms of the disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure. Accordingly, the disclosure is not intended to be so limited. Also, the term "comprising" is considered synonymous with the term "including" in the united states law. Likewise, whenever a composition, element, or group of elements is preceded by the transitional phrase "comprising," it is understood that we also contemplate the same composition or group of elements having the transitional phrase "consisting essentially of … …," "consisting of … …," "selected from the group consisting of … …," or "yes" before the recited composition, element, or elements, and vice versa.

Unless otherwise indicated, the phrases "consisting essentially of … … (consists essentially of)" and "consisting essentially of … … (consisting essentially of)" do not exclude the presence of other steps, elements or materials, whether or not specifically mentioned in the present specification, as long as such steps, elements or materials do not affect the basic and novel features of the present disclosure, and furthermore, they do not exclude impurities and variations normally associated with the elements and materials used.

While the present disclosure has been described with respect to various embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the present disclosure.

Claims (22)

1. A polymer composition comprising:

A C ₂-C₆ olefin homopolymer or a copolymer of two or more C ₂-C₂₀ alpha-olefins; and

From 250 to 15000ppm (based on the mass of the polymer composition) of one or more polyethylene glycols,

Wherein all polyethylene glycols of the polymer composition have a weight average molecular weight (Mw) of less than 40,000g/mol, and

Further wherein the polymer composition is substantially free of fluorine.

2. The polymer composition of claim 1 comprising a total of from 250 to 2,000ppm of polyethylene glycol.

3. The polymer composition of claim 2 comprising from 250 to 1,100ppm total polyethylene glycol.

4. A polymer composition comprising:

A C ₂-C₆ olefin homopolymer or a copolymer of two or more C ₂-C₂₀ alpha-olefins; and

From 300 to 15000ppm (based on the mass of the polymer composition) of a polymer processing aid,

Wherein the polymer processing aid comprises at least 80wt% (based on the total mass of the polymer processing aid) of one or more polyethylene glycols.

5. A polymer composition according to claim 3, wherein the polymer processing aid comprises at least 99wt% of the polyethylene glycol.

6. The polymer composition of claim 4, wherein the polymer processing aid consists essentially of the polyethylene glycol.

7. The polymer composition of any of claims 4-6 comprising a total of from 250 to 2,000ppm of the polymer processing aid.

8. The polymer composition of claim 7 comprising a total of from 250 to 1,100ppm of the polymer processing aid.

9. The polymer composition according to any of the preceding claims, wherein each polyethylene glycol of the polymer composition has a Mw in the range from 1,500 to 35,000 g/mol.

10. The polymer composition of claim 9, wherein each polyethylene glycol of the polymer composition has a Mw in the range of from 5,000 to 20,000 g/mol.

11. The polymer composition of claim 10, wherein each polyethylene glycol of the polymer composition has a Mw in the range from 7,500 to 11,000 g/mol.

12. The polymer composition according to any of the preceding claims, wherein at least one polyethylene glycol of the polymer composition has a Molecular Weight Distribution (MWD) in the range from 1.0 to 2.0.

13. The polymer composition of claim 12, wherein the at least one polyethylene glycol has a MWD in the range of from 1.0 to 1.2.

14. The polymer composition of any of the preceding claims, wherein the polymer composition comprises an ethylene copolymer comprising units derived from ethylene and units derived from one or more C ₃ to C ₂₀ a-olefins.

15. The polymer composition of claim 14, wherein the ethylene copolymer is a metallocene-catalyzed linear low density polyethylene (mLLDPE) comprising units derived from ethylene and units derived from 1-butene, 1-hexene, or 1-octene.

16. The polymer composition of claim 14 or claim 15, wherein the ethylene copolymer has a density in the range of from 0.905 to 0.945g/cm ³ and a melt index (ASTM D1238, at 190 ℃, under 2.16kg load) in the range of from 0.1 to 5.0g/10 min.

17. The polymer composition of claim 15 or claim 16, wherein the polyethylene glycol of the polymer composition has a Mw in the range of from 7,500 to 11,000g/mol, and further wherein:

i. the ethylene copolymer has a melt index of less than 0.45g/10min (190 ℃,2.18 kg); and

The polymer composition comprises from 800ppm to 1100ppm polyethylene glycol.

18. The polymer composition of claim 15 or claim 16, wherein the polyethylene glycol of the polymer composition has a Mw in the range of from 7,500 to 11,000g/mol, and further wherein:

i. The ethylene copolymer has a melt index greater than or equal to 0.45g/10min (190 ℃,2.18 kg); and

The polymer composition comprises from 250ppm to 600ppm of polyethylene glycol.

19. The polymer composition according to any of the preceding claims, wherein the polymer composition is formed by a process comprising: melt blending the one or more polyethylene glycols and the homopolymer or copolymer to obtain a polymer composition having polyethylene glycol uniformly distributed in the homopolymer or copolymer.

20. The polymer composition of claim 19, wherein the melt blending comprises co-extruding the one or more polyethylene glycols and the homopolymer or copolymer in a compounding extruder, optionally under an oxygen-free atmosphere; obtaining an extrudate comprising said polyethylene glycol and said homo-or copolymer; and granulating the extrudate to form the polymer composition comprising the polyethylene glycol.

21. A blown film made from the polymer composition of any of the preceding claims, wherein the film has one or more of the following:

1% secant Modulus (MD) is within +/-5% of the value (psi) of a film made using fluoropolymer-based PPA instead of the one or more polyethylene glycols but otherwise identical;

elmendorf tear (MD) is within +/-10% of the value (g) of a film made using fluoropolymer-based PPA instead of the one or more polyethylene glycols but otherwise identical;

The total haze is within +/-25% of the value (in%) of an otherwise identical film made using fluoropolymer-based PPA instead of the one or more polyethylene glycols, and/or the total haze is less than 6%;

Gloss (MD) is within +/-12% of the value (in GU) of a film made using fluoropolymer-based PPA instead of the one or more polyethylene glycols but otherwise identical; and

The dart falls within +/-1% of the value (g) of a film made using fluoropolymer-based PPA instead of the one or more polyethylene glycols but otherwise identical.

22. The blown film of claim 21, wherein the film has all of the characteristics (i) - (v).