Compositions with hyperbranched polyester polyol polymer processing additives

Abstract

A hyperbranched polyester polyol for use as a polymer processing additive, the hyperbranched polyester polyol having from 40% to 60% linear carbons based on the total number of linear, dendritic and terminal carbons. Compositions containing thermoplastic polymers and such polymer processing additives are described, as well as methods of extruding thermoplastic polymers containing such polymer processing additive compositions. Additional uses of a synergist selected from the group consisting of polyethylene glycol, polyethylene oxide, polycaprolactone and combinations thereof are also described.

Description

Technical Field

[0001] The present disclosure relates to hyperbranched polyester polyol polymer processing additives and thermoplastic polymer compositions containing the hyperbranched polyester polyol polymer processing additives. Summary of the invention

[0002] Briefly, in one aspect, the present disclosure provides a composition comprising a major amount of a thermoplastic polymer and a hyperbranched polyester polyol polymer processing additive. The hyperbranched polyester polyol has 40% to 60% linear carbon based on the total number of linear, dendritic and terminal carbons. In some cases, the composition further comprises a synergist, such as polyethylene glycol, polyethylene oxide, polycaprolactone and combinations thereof.

[0003] In another aspect, the present disclosure provides a method for forming a film, the method comprising blending a thermoplastic polymer with a hyperbranched polyester polyol and optionally a synergist to form a composition, and extruding the composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 The hyperbranched polyester polyols 1 H and 13 C NMR.

[0005] Figure 2 A heteronuclear multiple bond correlation diagram of a second hyperbranched polyester polyol is shown.

[0006] Figure 3 The elimination of melt fracture achieved with various hyperbranched polyester polyol polymer processing additives is shown. DETAILED DESCRIPTION

[0007] Extrusion of polymeric materials in the formation and shaping of articles is an integral part of the plastic or polymer article industry. The quality of the extruded article and the overall success of the extrusion process are affected by the interaction of the fluid material with the extrusion die. The requirement to smooth the extrudate surface competes with and must be optimized relative to the economic advantage of extruding the polymer composition at the fastest possible speed (e.g., highest shear rate).

[0008] For any melt-processable thermoplastic polymer composition, there is a critical shear rate above which the surface of the extrudate becomes rough or distorted, and below which the extrudate will be smooth. At shear rates slightly above the critical shear rate, defects in extruded thermoplastics can take the form of "shark skin," a loss of surface gloss, or more severely, ridges that appear somewhat transverse to the direction of extrusion. At high shear rates, the extrudate can undergo "continuous melt fracture," becoming severely distorted. At rates below where continuous melt fracture is just observed, some thermoplastics can also undergo "annular melt fracture," a process in which the surface of the extrudate changes from smooth to rough.

[0009] Other problems encountered during the extrusion of thermoplastic polymers include accumulation of polymer at the orifice of the die (known as die buildup or die drool), high back pressure during extrusion, and excessive degradation of the polymer or low melt strength due to the need to use higher extrusion temperatures to overcome these problems. These problems slow down the extrusion process, either because the process must be stopped to clean the equipment or because the process must be carried out at a lower speed.

[0010] Additives for polymer processing (also called "polymer processing additives" or "PPAs") have been used to address such problems. PPAs can reduce melt stagnation at the die and increase the shear rate at which thermoplastic polymers can be extruded without visible melt defects.

[0011] Hyperbranched polymers are known in the art. Hyperbranched polymers are similar to dendritic polymers in that both are characterized by highly branched 3-dimensional structures. All bonds originate from the core, with branch junctions located at each monomer unit and multiple reactive chain ends. A branch generation consists of structural units radially connected to the core or to the structural units of the previous generation, which extend outward. The structural unit has at least two monofunctional groups and / or at least one monofunctional group and one polyfunctional group. The term polyfunctional should be understood as having a functionality of 2 or more. New structural units can be connected to each functional group, resulting in higher branch generations. Unlike dendritic polymers, hyperbranched polymers have irregular structures and the positioning of their functional groups; therefore, when dendritic polymers are described as having precise "generations", hyperbranched polymers are described as having "pseudo-generations". The resulting hyperbranched polymer has a core, at least one branch pseudo-generation, and an outer surface consisting of functional end groups.

[0012] Hyperbranched polymers of the polyester type are described, for example, in International Publication No. WO 96 / 12754 and US Pat. No. 6,300,424 B1.

[0013] Fluoropolymers are often used as polymer processing additives. In some cases, the performance of fluorinated PPAs can be enhanced by incorporating "synergists." For example, U.S. Pat. No. 6,818,695 B2 ("Extrudable Thermoplastic Compositions," Dillon et al.) describes the use of hyperbranched polyesters and hyperbranched polyester amides as synergists for use with various fluorinated polymer processing additives. Although synergists are effective in reducing the amount of fluorinated material required, in some applications, it is desirable to eliminate the use of fluorinated PPAs.

[0014] Hong et al. describe the use of functionalized hyperbranched polyesters as polymer processing additives. Journal of Rheology Journal of Rheol. 43(3) May / June 1999, pp. 781-93). The hydroxyl groups of the hyperbranched polyesters are reacted with C-14 alkanes to form hexadecyl-terminated polymers, or the hydroxyl groups are reacted with a mixture of eicosanoic and docosanoic acids such that 50% to 90% of the groups are terminated with C-20 / 22 alkanes. Hong and Coombs et al. also describe the use of hyperbranched polyesters functionalized with eicosanoic and docosanoic acids as polymer processing additives. Polymer ,41(2000),pp.7705-13).

[0015] The present inventors have found that in the case of certain hyperbranched polyester polyols, the hydroxyl groups do not need to be functionalized to provide the benefits of polymer processing additives, such as reducing melt defects. These benefits can be achieved even in the absence of synergists, which have been used to enhance the performance of other polymer processing additives or fluorinated materials.

[0016] As used herein, "hyperbranched polyester polyol" refers to a hydroxyl-functional hyperbranched polyester in which at least 90 mole % of the functional end groups are hydroxyl groups, for example, in some cases, at least 95 mole % or even 100 mole % of the functional end groups are hydroxyl groups. The term "hyperbranched polyester polyol" distinguishes the hydroxyl-functional hyperbranched polyesters of the present disclosure from functionalized hyperbranched polyesters in which a higher percentage (e.g., 50%, 90% or even 100%) of the hydroxyl groups are replaced by, for example, fatty acid or amine functional groups.

[0017] A wide range of hyperbranched polyester polyols are available from Perstorp AB under the trade name BOLTORN. These materials are described as having a dendritic structure formed by polymerisation of a core and 2,2-dimethylolpropionic acid.

[0018] As shown in the examples, when combined with thermoplastic polymers, the hyperbranched polyester polyols of the present disclosure act as polymer processing additives. That is, the hyperbranched polyester polyols shorten the time to clear melt fracture. In some cases, the hyperbranched polyester polyols also reduce the pressure drop of extrusion.

[0019] In some cases, the thermoplastic polymer to which the hyperbranched polyester polyol is added includes a polymer obtained by homopolymerization or copolymerization of olefins. Suitable olefins have the general structure CH2=CHR, wherein R is hydrogen or an alkyl group, and generally, the alkyl group contains no more than 10 carbon atoms, and preferably one to four carbon atoms. Representative olefins are ethylene, propylene and butene-1. Representative examples of olefin polymers include polyethylene, polypropylene, polybutene-1, poly(3-methylbutene), poly(4-methylpentene) and copolymers of ethylene with propylene, butene-1, hexane-1, octene-1, decene-1, 4-methyl-1-pentene and octadecene-1.

[0020] In some cases, the thermoplastic polymer is a copolymer of one or more olefins and up to about 30 weight percent (but preferably 20 weight percent or less) of one or more monomers copolymerizable with such olefins. Representative monomers that can be copolymerized with olefins are vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl chloroacetate, vinyl chloropropionate, acrylic acid and α-alkyl acrylic acid monomers; and their alkyl esters, amides and nitriles, such as acrylic acid, methacrylic acid, ethacrylic acid, methyl acrylate, ethyl acrylate, N,N-dimethylacrylamide, methacrylamide, acrylonitrile; vinyl aromatic monomers such as styrene, o-methoxystyrene, p-methoxystyrene and vinyl naphthalene; vinyl halides and vinylidene halide monomers such as vinyl chloride, vinylidene chloride, vinylidene bromide; alkyl ester monomers of maleic acid and fumaric acid such as dimethyl maleate, diethyl maleate; vinyl alkyl ether monomers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, 2-chloroethyl vinyl ether; and vinyl pyridine monomers, N-vinyl carbazole monomers and N-vinyl pyrrolidone monomers.

[0021] In some cases, the thermoplastic polymer further comprises a metal salt of an olefin copolymer, or a blend thereof, which comprises free carboxylic acid groups. Illustrative examples of metals that can be used to provide the carboxylic acid polymer salt are monovalent, divalent, or trivalent metals such as sodium, lithium, potassium, calcium, magnesium, aluminum, barium, zinc, zirconium, beryllium, iron, nickel, and cobalt.

[0022] Representative blends of thermoplastic hydrocarbon polymers useful in the present invention are blends of polyethylene and polypropylene, blends of low density polyethylene and high density polyethylene, blends of polyethylene and olefin copolymers containing copolymerizable monomers, some of which have been described above, for example, ethylene and acrylic acid copolymers; ethylene and methyl acrylate copolymers; ethylene and ethyl acrylate copolymers; ethylene and vinyl acetate copolymers; ethylene, acrylic acid and ethyl acrylate copolymers, and ethylene, acrylic acid and vinyl acetate copolymers.

[0023] The thermoplastic polymer can be used in powder, pellets, granules or any other extrudable form. In some cases, the thermoplastic polymer may contain other additives such as, for example, anti-blocking agents, slip agents, light stabilizers and fillers.

[0024] Typically, the amount of polymer processing additives (i.e., the amount of hyperbranched polyester polyol polymer processing additives) contained in the thermoplastic composition is not particularly limited. However, for compositions intended to be extruded into finished articles, it may be desirable to minimize the amount of polymer processing additives while maintaining desired processing properties. In some cases, such compositions and articles contain no more than 5000 ppm of polymer processing additives based on the total weight of the composition. For example, in some cases, such compositions or articles contain 100 ppm to 3000 ppm, such as 500 ppm to 1500 ppm of polymer processing additives based on the total weight of the composition.

[0025] Since it may be difficult to control the amount of polymer processing additives at such low levels, in some cases, a masterbatch may be used. Such a masterbatch contains a higher proportion of the polymer processing additive composition in a host resin. The host resin is selected to be compatible with the thermoplastic polymer and may be the same or different from the thermoplastic polymer. The amount of polymer processing additive in the masterbatch is not critical. In some cases, the masterbatch contains 0.2 wt % to 10 wt %, such as 0.5 wt % to 5 wt % of the polymer processing additive.

[0026] The polymer processing additives can be compounded into the thermoplastic polymer using known equipment and methods, and the compounded composition can be processed. For example, the polymer processing additives of the present disclosure can be used in the processing of thermoplastic polymers, including, for example, film extrusion, extrusion blow molding, injection molding, pipe, wire or cable extrusion, and fiber production.

[0027] Examples: The materials used to prepare the polymer processing additive compositions used in the following examples are summarized in Table 1.

[0028] Table 1: Overview of the hyperbranched polyester polyols (HPP) used in the examples .

[0029]

[0030] Samples of each hyperbranched polyester polyol were dissolved in deuterated dimethyl sulfoxide (DMSO) and nuclear magnetic resonance (NMR) spectra were obtained on a Bruker AVANCE 500MHz NMR spectrometer equipped with a broadband cryoprobe. 2D NMR spectra were obtained for distribution. Quantitative analysis was obtained using samples dissolved in deuterated DMSO containing GdCl with a reverse gated pulse sequence. 13 C NMR. 1 H and 13 Peaks associated with alcohol, ester / ether, ester / carboxyl, and quaternary (4°) carbon groups were identified in C NMR. 13 The quaternary carbon region (45 ppm-51 ppm) of the C spectrum was used to quantify linear and dendritic branching.

[0031] HPP-2A 1 H and 13 C NMR shows Figure 1 In. 1 The H spectrum 100 shows the chemical shifts (x-axis) of the peaks in the normalized intensity (y-axis) of the alcohol (102), ester / ether (104), DMSO (106), and methyl (108). 13 The chemical shifts of the peaks in the normalized intensities of ester / carboxyl (210), ester / ether (204), 4° carbon (212), DMSO (206), and methyl (208) are shown in the C spectrum 200.

[0032] Heteronuclear multiple bond correlation (HMBC) was used to verify the identity of the quaternary carbon peaks. For each ester group attached to the quaternary carbon, the carbon chemical shift shifted by approximately 2 ppm, allowing for resolution between the different groups. The HMBC curve of HPP-4A is shown in Figure 2 middle.

[0033] Various quaternary carbons are shown below in exemplary hyperbranched polyester polyols of formula (I).

[0034] (I)

[0035] The quaternary carbon at the center of the hyperbranched polyester polyol from which the branches extend is identified as "C". The exact nature of the connection to the C carbon depends on the specific core used. The branches result from the polymerization of 2,2-dimethylol propionic acid as shown in Formula II below.

[0036] (II)

[0037] Quaternary carbons with two ester-containing bonds and one hydroxyl functional group are identified as linear ("L") carbons, since the polyester polyol branches extend through these carbon atoms without additional branching. Quaternary carbons with three ester-containing bonds and no hydroxyl functional groups are identified as dendritic ("D") carbons, since the polyester polyol chain branches into two polyester polyol chains at these carbon atoms, creating an additional dendritic structure. Finally, quaternary carbons with only one attached ester-containing bond and two hydroxyl functional groups are identified as terminal ("T") carbons, since the polyester polyol branches terminate at these carbon atoms.

[0038] The average number of each type of quaternary carbon group per central carbon and the expected molecular weight of the molecule are shown in Table 2.

[0039] Table 2: Quaternary Carbon Groups per Central ("C") Carbon .

[0040] sample center Linear Dendritic End MW HPP-2A 1.0 9.3 1.9 5.5 2250 HPP-2B 1.0 13.5 0.7 4.8 2519 HPP-3A 1.0 27.3 3.2 9.1 4944 HPP-4A 1.0 32.9 8.1 13.0 6625 HPP-5A 1.0 93.5 16.3 31.4 16857 HPP-5B 1.0 78.7 15.3 29.5 14769 HPP-5C 1.0 111.1 62.4 31.3 24251

[0041] Sample Preparation Each of the hyperbranched polyester polyols of Table 1 was compounded as a masterbatch at a level of 2 wt% in a linear low density polyethylene (LLDPE) resin along with other components typically used for blown film applications. The masterbatch was prepared in 3 kg batches by vigorous shaking in a bag: 60 g of ground / powdered hyperbranched polyester polyol, 2935 g of granular resin (2MI LLDPE, EM 1002.09, available from Exxon Mobil), 3.0 g of a heat stabilizer (IRGANOX B900, available from BASF), and 2.1 g of an acid neutralizer (zinc stearate).

[0042] Each resulting formulation is fed to a laboratory scale, intermeshing, counter-rotating, non-ventilated, air-cooled conical twin screw (HaakeBuchler Rheomix TW-100) with a front inner diameter of 33 mm. The mixture is gravity fed to the throat of the extruder and exposed to air at a rate of 55 g / min. The specific temperature distribution of the extruder in the 3 barrel zones (feeding, measuring, mixing) and die zone is 170°C / 190°C / 200°C / 200°C, respectively. The extruder is operated at 150RPM to perform the first "compounding". The second compounding is operated with the same temperature distribution but the rotation speed is 90RPM, while the material is perfused. The material of the 4-minute "purge" is discarded at the beginning of each pass, and the material is collected after the second batch forms a masterbatch for the following steps.

[0043] Melt fracture performance. Melt fracture performance was tested by mixing the required amount of each masterbatch into a linear low density polyethylene host resin (0.9MI ZN LLDPE; MARFLEX 7109, available from Chevron Philips Chemicals). Extrudable materials were prepared by diluting the individual masterbatches to a total target level of 1000 ppm of HPP material in the host resin. The mixture was extruded at 210°C using a 0.9 mm gap, 14 L / gap die at 10.5 kg / h and 220 / s, combined with 6000 ppm of talc antiblock (ABT 7500 added as a masterbatch; AMPACETM B#101558) and 1000 ppm of a slip additive (ERUCAMIDE added as a masterbatch; AMPACET MB#10090).

[0044] The LABTECH blown film production line with 40mm, 30 / 1 extruder was used for the test. The die head has a spiral design, a diameter of 40mm and a die gap of 0.9mm. The pressure was recorded every 10 minutes and the sample of the film was collected. The film was checked for melt fracture (MF) and expressed as the percentage of the film area covered with MF. The time corresponding to the disappearance of the last MF band or the time to remove melt fracture (TTC) was recorded, and the test was stopped at this point. If any MF is retained at the end of two hours, the test was stopped and the final MF level was recorded.

[0045] The results are Figure 3 and are shown in Table 3. As shown, samples HPP-2A and HPP-5C provide significantly better elimination of melt fracture than the remaining hyperbranched polyester polyols. HPP-2A clears melt fracture within 80 minutes, while HPP-5C clears melt fracture within only 60 minutes.

[0046] Table 3: Elimination of melt fracture .

[0047] minute HPP-2A HPP-2B HPP-3A HPP-4A HPP-5A HPP-5B HPP-5C 0 100 100 100 100 100 100 100 10 100 100 100 100 100 100 100 20 100 100 100 100 100 100 100 30 48 100 100 100 100 99 66 40 22 97 100 98 100 93 13 50 9 90 100 86 91 79 4 60 1.5 76 100 60 73 56 0 70 0.5 58 72 42 53 34 80 0 40 49 23 38 22 90 21 19 10 20 9 100 9 10 4 11 6.5 110 1.5 3.5 2.5 3 2 120 0 0 1 2 0.5

[0048] Table 4 summarizes the time to clear melt fracture (TTC) and the remaining melt fracture (if any), as well as the relative amounts of linear, dendritic, and terminal carbons shown as a percentage of the total number of linear, dendritic, and terminal carbons based on the data in Table 2.

[0049] Table 4: Melt fracture data and relative amounts of linear, dendritic and terminal branching .

[0050] sample TTC (minutes) Remaining MF Linear Dendritic End HPP-2A 80 N / A 56％ 11％ 33％ HPP-2B 120 0 71％ 4％ 25％ HPP-3A 120 0 69％ 8％ 23％ HPP-4A 120 1 61％ 15％ 24％ HPP-5A 120 2 66％ 12％ 22％ HPP-5B 120 0.5 64％ 12％ 24％ HPP-5C 60 N / A 54％ 30％ 15％

[0051] As shown, hyperbranched polyester polyols having less than 60% linear carbon per central carbon correspond to samples having superior performance in eliminating melt fracture compared to all samples having greater than 60% linear content. Although all hyperbranched polyester polyols must contain both dendritic and terminal carbons, the relative amounts of dendritic and terminal carbons do not appear to be critical, as HPP-2A contains 11% dendritic carbons and 33% terminal carbons, while HPP-5C contains 30% dendritic carbons and 15% terminal carbons. Thus, hyperbranched polyester polyols containing less than 60% linear carbons based on the total number of linear, dendritic, and terminal carbons, such as hyperbranched polyester polyols having 40% to 60%, such as 45% to 60%, 50% to 60%, such as 52% to 58%, or even 53% to 57% linear carbons, are highly effective as polymer processing additives.

[0052] Can improve the performance of polymer processing additive by adding synergist to form polymer processing additive composition.In some cases, synergist further shortens the time of melt fracture.In some cases, synergist further reduces the pressure drop of extrusion.In some cases, synergist can be used to reduce the amount of hyperbranched polyester polyol polymer processing additive, maintains the same or similar performance simultaneously.

[0053] Suitable synergists include polyethylene glycol, poly (ethylene oxide) and polycaprolactone. In some cases, polyethylene glycol has 1000 dalton to 50,000 dalton, for example, 4000 dalton to 25,000 dalton number average molecular weight. In some cases, poly (ethylene oxide) has 10,000 dalton to 500,000 dalton, for example, 15,000 dalton to 400,000 dalton number average molecular weight. In some cases, polycaprolactone has 2,000 dalton to 200,000 dalton, for example, 50,000 dalton to 150,000 dalton number average molecular weight. The number average molecular weight can be measured by gel permeation chromatography (GPC) using polyethylene glycol and poly (ethylene oxide) standards. GPC equipment and standards are available from Agilent Technologies, Inc.

[0054] Typically, the weight ratio of the polymer processing additive to the synergist in the polymer processing additive composition is from 90: 10 to 10: 90. In some cases, the weight ratio is from 75:25 to 25:75, or even from 60:40 to 40:60.

[0055] Generally, the amount of the polymer processing additive composition (i.e., the combined amount of the hyperbranched polyester polyol polymer processing additive and the synergist) contained in the thermoplastic composition is not particularly limited. However, for compositions intended to be extruded into finished articles, it may be desirable to minimize the amount of the polymer processing additive composition while maintaining the desired processing properties. In some cases, such compositions and articles contain no more than 5000 ppm of the polymer processing additive composition, based on the total weight of the composition. For example, in some cases, such compositions or articles contain from 100 ppm to 3000 ppm, such as from 500 ppm to 1500 ppm of the polymer processing additive composition, based on the total weight of the composition.

[0056] In some cases, each component of the polymer processing additive composition can be added separately to the thermoplastic polymer. In some cases, the hyperbranched polyester polyol polymer processing additive and the synergist can be blended, for example, in a desired ratio and then added together to the thermoplastic polymer. For example, the components of the polymer processing additive composition can be blended by physical mixing or melt blending. In such cases, additional amounts of the hyperbranched polyester polyol polymer processing additive or the synergist can be added to the thermoplastic polymer to adjust their amounts.

[0057] Since it may be difficult to control the amount of the polymer processing additive composition at such low levels, in some cases a masterbatch may be used. Such a masterbatch contains a higher proportion of one or more components of the polymer processing additive composition in a host resin. The host resin is selected to be compatible with the thermoplastic polymer and may be the same as or different from the thermoplastic polymer.

[0058] In some cases, a separate masterbatch can be used, one of which contains a hyperbranched polyester polyol polymer processing additive and a synergist. For example, this may be useful when it may be desirable to adjust the ratio of a hyperbranched polyester polyol polymer processing additive and a synergist. Equally, the amount of a particular component in the masterbatch is not critical. In some cases, the masterbatch contains 0.2 wt % to 10 wt %, for example 0.5 wt % to 5 wt % of those components of the polymer processing additive composition present in the masterbatch. In some cases, a single combined masterbatch contains both a hyperbranched polyester polyol polymer processing additive and a synergist.

[0059] A masterbatch of HPP-5C (55% linear) was prepared at a 3 wt% level. The masterbatch was prepared in 2 kg batches by vigorous shaking in a bag: 60 g of ground / powdered hyperbranched polyester polyol, 1940 g of granular resin (2MI LLDPE, EM1002.09, available from Exxon Mobil), 2.0 g of heat stabilizer (IRGANOX B900, available from BASF) and 1.4 g of acid neutralizer (zinc stearate).

[0060] In a similar manner, a masterbatch of polyethylene glycol synergist was prepared. Specifically, 2 kg of patch was prepared by vigorous shaking in a bag: 60 g of polyethylene glycol (8000 MW, purchased from Dow Chemical Company), 1940 g of granular resin (2MI LLDPE, EM 1002.09, purchased from Exxon Mobil), 2.0 g of heat stabilizer (IRGANOX B900, purchased from BASF) and 1.4 g of acid neutralizer (zinc stearate).

[0061] Each resulting formulation is fed to a laboratory scale, intermeshing, counter-rotating, non-ventilated, air-cooled conical twin screw (HaakeBuchler Rheomix TW-100) with a front inner diameter of 33 mm. The mixture is gravity fed to the throat of the extruder and exposed to air at a rate of 55 g / min. The specific temperature distribution of the extruder in the 3 barrel zones (feeding, measuring, mixing) and die zone is 170°C / 190°C / 200°C / 200°C, respectively. The extruder is operated at 150RPM to perform the first "compounding". The second compounding is operated with the same temperature distribution but the rotation speed is 90RPM, while the material is perfused. The material of the 4-minute "purge" is discarded at the beginning of each pass, and the material is collected after the second batch forms a masterbatch for the following steps.

[0062] Melt fracture properties. Melt fracture properties were tested by mixing the required amount of each masterbatch into a linear low density polyethylene host resin (0.9MI ZN LLDPE; MARFLEX 7109, available from Chevron Philips Chemicals). Extrudable materials were prepared by diluting the individual masterbatches to a total target level of 500 ppm or 1000 ppm of HPP material and 0 ppm or 500 ppm of synergist in the host resin as listed in Table 5. The mixtures were extruded at 210°C using a 0.9 mm gap, 14 L / gap die at 10.5 kg / h and 220 / s, combined with 6000 ppm of talc antiblock (ABT 7500 masterbatch; AMPACET MB#101558) and 1000 ppm of a slip additive (ERUCAMIDE masterbatch; AMPACET MB#10090).

[0063] The LABTECH blown film production line with 40mm, 30 / 1 extruder was used for the test. The die head has a spiral design, a diameter of 40mm and a die gap of 0.9mm. The pressure was recorded every 10 minutes and the sample of the film was collected. The film was checked for melt fracture (MF) and expressed as the percentage of the film area covered with MF. The time corresponding to the disappearance of the last MF band or the time to remove melt fracture (TTC) was recorded, and the test was stopped at this point. If any MF is retained at the end of two hours, the test is stopped and the final MF level is recorded. The composition of the sample is shown in Table 5, wherein all amounts are reported in ppm by weight based on the gross weight of the extruded composition. The results are summarized in Table 6.

[0064] Table 5: Compositions with hyperbranched polyester polyol PPA and PEG synergist .

[0065] sample PPA PPA(ppm) PEG(ppm) A HPP-5C 500 0 B HPP-5C 500 500 C HPP-5C 1000 0

[0066] Table 6: Melt fracture data of hyperbranched polyester polyol PPA and PEG enhancer

[0067]

[0068] As shown, the addition of 500 ppm of PEG synergist improves melt fracture elimination compared to 500 ppm of hyperbranched polyester polyol alone. In addition, melt fracture elimination is satisfactory while the required amount of hyperbranched polyester polyol is reduced by 50% compared to the sample containing 1000 ppm of hyperbranched polyester polyol.

Claims

1. A composition comprising greater than 50% by weight of a thermoplastic polymer and a polymer processing additive comprising a hyperbranched polyester polyol having 40% to 60% linear carbons based on the total number of linear, dendritic and terminal carbons; wherein The hyperbranched polyester polyol is a hydroxyl-functional hyperbranched polyester having functional end groups, wherein at least 90 mol % of the functional end groups are hydroxyl groups.

2. The composition of claim 1, wherein the hyperbranched polyester polyol has 50% to 60% linear carbons based on the total number of linear, dendritic and terminal carbons.

3. The composition of claim 2, wherein the hyperbranched polyester polyol has 52% to 58% linear carbons based on the total number of linear, dendritic and terminal carbons.

4. The composition of any one of the preceding claims, wherein the composition comprises from 100 ppm to 3000 ppm by weight of the polymer processing additive based on the weight of the thermoplastic polymer.

5. The composition of any preceding claim, wherein the thermoplastic polymer comprises a polyolefin.

6. The composition of claim 5, wherein the polyolefin comprises linear low density polyethylene.

7. The composition according to any one of the preceding claims, wherein the branches of the hyperbranched polyester polyol comprise polymerized units of 2,2-dimethylolpropionic acid.

8. The composition of any of the preceding claims, wherein the composition further comprises a synergist selected from the group consisting of polyethylene glycol, poly(ethylene oxide), polycaprolactone, and combinations thereof.

9. The composition of claim 8, wherein the synergist comprises polyethylene glycol.

10. The composition according to claim 8 or 9, wherein the weight ratio of the hyperbranched polyester polyol to the synergist is 25:75 to 75:

25.

11. A method for forming a film, the method comprising: A) blending a first thermoplastic polymer with a polymer processing additive comprising a hyperbranched polyester polyol having less than 60% linear carbons based on the total number of linear, dendritic and terminal carbons to form a composition, wherein the hyperbranched polyester polyol is a hydroxyl functional hyperbranched polyester having functional end groups, wherein at least 90 mole % of the functional end groups are hydroxyl groups, and B) Extruding the composition.

12. The method of claim 11, wherein blending the first thermoplastic polymer with the polymer processing additive comprises blending a first masterbatch with the thermoplastic polymer, wherein the first masterbatch comprises the polymer processing additive and a second thermoplastic polymer.

13. The method of claim 12, wherein the first thermoplastic polymer and the second thermoplastic polymer are different polymers.

14. The method of claim 11, further comprising blending a synergist selected from the group consisting of polyethylene glycol, poly(ethylene oxide), polycaprolactone, and combinations thereof with the first thermoplastic polymer and the polymer processing additive to form the composition.

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