Dimer acid as polymer processing aid for polyethylene

Abstract

Embodiments of a formulation comprises at least 90 wt.% ethylene-based polymer and dimer acid, wherein the dimer acid is a polymer processing aid used to reduce melt fracture during extrusion.

Description

DIMER ACID AS POLYMER PROCESSING AID FOR POLYETHYLENECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 678,804 filed August 2, 2024, the contents of which are incorporated in their entirety herein.TECHNICAL FIELD

[0002] The present disclosure generally relates to formulations comprising ethylene-based polymer and dimer acids and are specifically related to the use of these formulations to reduce melt fracture during extrusion.BACKGROUND

[0003] Plastics are used for a wide range of industrial applications, including packaging, construction, and wire and cable. However, many plastics suffer from melt fracture during extrusion, which is a phenomenon wherein the surface of the plastic becomes distorted with undulations or irregularities. Some types of melt fracture, such as sharkskin melt fracture, impact the surface of the plastic by causing irregular and sometimes scaly surface texture, which may reduce the glossiness of the surface.

[0004] Conventional processes for preventing melt fracture in polyethylene include using polymer processing aids (PPA) comprising fluoropolymer-based polymer (PFA). However, environmental concerns with fluoropolymers have spurred restrictions on these materials. Accordingly, a need exists for improved PPA formulations that may reduce melt fracture while also alleviating environmental concerns.SUMMARY

[0005] Embodiments of the present disclosure address these and other needs by providing formulations for polymer processing aids comprising at least 90 wt.% ethylene-based polymer and dimer acid. Dimer acid is a compound that is primarily obtained from tall oil, a byproduct of the paper industry. The tall oil fatty acid undergoes a process known as dimerization, resulting in dimer acid. Dimerization is achieved through the reaction of unsaturations on the tall oil (enereactions, Diels Alder reactions). The dimer acid with a small component of trimer acid, small component of remaining unreacted monomeric acid, and potentially small amount of polycyclic dimer acid can then optionally be hydrogenated to remove any remaining unsaturations.

[0006] In further embodiments, the formulation may also comprise a trimer acid. In further embodiments, the ethylene-based polymer may comprise linear low-density polyethylene, high- density polyethylene, or combinations thereof.

[0007] Additional features and advantages will be set forth in the detailed description that follows and, in part, will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows in addition to the claims.

[0008] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter.DETAILED DESCRIPTION

[0009] As used in this disclosure, the term “polymer” may refer to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term “homopolymer,” usually employed to refer to polymers prepared from only one type of monomer as well as “copolymer,” which refers to polymers prepared from two or more different monomers. The term “interpolymer,” as used herein, refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term interpolymer thus includes copolymers, and polymers prepared from more than two different types of monomers, such as terpolymers.

[0010] “Blend,” “polymer blend,” and like terms mean a composition of two or more polymers. Such a blend may or may not be miscible. Such a blend may or may not be phase separated. Such a blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and any other method known in the art. Blends are not laminates, but one or more layers of a laminate may contain a blend.Such blends can be prepared as dry blends, formed in situ (e.g., in a reactor), melt blends, or using other techniques known to those of skill in the art.

[0011] As used in this disclosure, the term “polyethylene” or “ethylene -based polymer” may refer to polymers comprising greater than 50% by mole of units which have been derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of ethylene-based polymer known in the art include Low Density Polyethylene (LDPE); Linear Low Density Polyethylene (LLDPE); Ultra Low Density Polyethylene (ULDPE); Very Low Density Polyethylene (VLDPE); single-site catalyzed Linear Low Density Polyethylene, including both linear and substantially linear low density resins (m-LLDPE); Medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE).

[0012] The term “LLDPE” includes both resins made using the traditional Ziegler-Natta catalyst systems and chromium-based catalyst systems as well as single-site catalysts, including, but not limited to, bis -metallocene catalysts (sometimes referred to as “m- LLDPE”), constrained geometry catalysts (CGC), and molecular catalysts. Resins include linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPEs contain less long chain branching than LDPEs and includes the substantially linear ethylene polymers which are further defined in U.S. Patent 5,272,236, U.S. Patent 5,278,272, U.S. Patent 5,582,923 and US Patent 5,733,155; the homogeneously branched linear ethylene polymer compositions such as those in U.S. Patent No. 3,645,992; the heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Patent No. 4,076,698; and / or blends thereof (such as those disclosed in US 3,914,342 or US 5,854,045). The LLDPEs can be made via gasphase, solution-phase or slurry polymerization or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0013] The term “HDPE” or “high density polyethylene” refers to ethylene-based polymers having densities greater than 0.935 g / cc, which are generally prepared with Ziegler-Natta catalysts, chrome catalysts or even metallocene catalysts.

[0014] As used herein “fluoropolymer” refers to polymeric compounds comprising fluorine, and is intended to be interpreted broadly so as to include what might be referred to as oligomericspecies. As a non-limiting example, the fluoropolymer may comprise molecules containing at least three, at least four, at least five, or at least six fluorine containing units.

[0015] As used herein, “essentially free of” means comprising less than 50 ppmw.

[0016] As used herein, “melt fracture” refers to the formation of defects on a polymeric extrudate under various processing conditions. The defects may be any deviation from a smooth, glossy, regular extrudate.

[0017] As used herein, “parts per million” or “ppm” refers to parts per million by weight.

[0018] As used herein, “polymer melt” refers to polymers or polymer blends that are at temperatures above their glass transition temperature, i.e. the temperature below which the physical properties of the polymers change to those of a glassy or crystalline state, and usually above their melting temperature. The polymer melts may present as highly viscous liquids, and may possess non-Newtonian or viscoelastic natures.

[0019] As used herein, “dimer acid” refers to dicarboxylic acids that are prepared by dimerizing unsaturated fatty acids. Similarly, “trimer acid” refers to tricarboxylic acids prepared from unsaturated fatty acids.

[0020] Reference will now be made in detail to embodiments of formulations as described herein.

[0021] Embodiments of the formulation may include at least 90 wt.% ethylene-based polymer and dimer acid. In embodiments, the formulations described herein comprise a dimer acid. In one or more embodiments, the dimer acid may be present in a mixture comprising dimer acids and trimer acids Dimer acids may be present in a greater amount than trimer acids. In one or more embodiments, the mixture comprising the dimer acids and trimer acids comprise from a minimum of 51 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 90 wt.%, or 95 wt.% dimer acids to a maximum of 55 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 90 wt.%, 95 wt.%, or 100 wt.% dimer acids. Additionally, the mixture may also comprise some amount of monomeric acid (e.g., non-dimerized or non-trimerized carboxylic acid) in addition to the dimer acid and trimer acid, for example, less than 5 wt.%, less than 2 wt.%, or less 1 wt.% monomeric acid.

[0022] In embodiments, the dimer acid may comprise the structure of Formula (I), Formula(II), Formula (III), or mixtures thereof.Formula (I) Formula (II) Formula (III)

[0023] As shown, Formula (II) is the hydrogenated dimer acid of Formula (I). In specific embodiments, Ri comprises a C4-C12 alkyl or a C4-C12 alkenyl when R4 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with terminal carboxylic acid; R2 comprises a C4-C12 alkyl or a C4-C12 alkenyl when R3 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R3 comprises a C4-C12 alkyl or a C4-C12 alkenyl when R2 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R4 comprises a C4-C12 alkyl or a C4-C12 alkenyl when Ri comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; and R5 and Re independently comprise a hydrogen, C1-C12 alkyl, or a C1-C12 alkenyl.

[0024] In one embodiment, the dimer acid may be a dimer acid composition having a CAS number of 61788-89-4. In one or more embodiments, the dimer acid comprises a dimer of oleic acid.

[0025] In other embodiments, a formulation comprises a dimer acid wherein the dimer acid comprises the structure of any one of Formula (I), Formula (II), or Formula (III).

[0026] In Formula (I), Formula (II), or both, Ri may comprise a C4-C12 alkyl or a C4-C12 alkenyl when R4 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R2 may comprise a C4-C12 alkyl or a C4-C12 alkenyl when R3 comprisesa C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R3 may comprise, independently or simultaneously, a C4-C12 alkyl or a C4-C12 alkenyl when R2 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R4 comprises a C4-C12 alkyl or a C4-C12 alkenyl when Ri comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; and R5 and Re independently comprise a hydrogen, C1-C12 alkyl, or a C1-C12 alkenyl.

[0027] In Formula (III), Ri may comprise a C4-C12 alkyl or a C4-C12 alkenyl when R4 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R2 may comprise a C4-C12 alkyl or a C4-C12 alkenyl when R3 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid;

[0028] In other embodiments, the dimer acid is in a mixture having a majority of the structure of Formula (I) for non-hydrogenated dimer acid or Formula (II) for hydrogenated dimer acid.Formula (IV) Formula (V)

[0029] In embodiments, the formulations described herein may further comprise a trimer acid. In embodiments, the trimer acid may comprise the structure of Formula (IV), Formula (V), or mixtures thereof. As shown, Formula (V) is the hydrogenated trimer acid of Formula (IV). In embodiments, Ri comprises a C4-C12 alkyl or a C4-C12 alkenyl when R4 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R2 comprises a C4-C12 alkyl or a C4-C12 alkenyl when R3 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R3 comprises a C4-C12 alkyl or a C4-C12 alkenyl when R2 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R4 comprises a C4-C12 alkyl or a C4-C12 alkenyl when Ri comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; R5, Re, R9, and Rio independently comprise a hydrogen, a C1-C12 alkyl, or a C1-C12 alkenyl; R7 comprises a C4-C12 alkyl or aC4-C12 alkenyl when Rs comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; and Rs comprises a C4-C12 alkyl or a C4-C12 alkenyl when R7 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid.

[0030] In embodiments, the formulations described herein may further comprise a monomeric fatty acid.

[0031] Various compositions are considered suitable for the ethylene-based polymer in the formulations. In one or more embodiments, the ethylene-based polymer may comprise LLDPE, HDPE, or combinations thereof. In embodiments, the ethylene-based polymer may comprise a melt index (I2) of less than 4.0 dg / min as measured according to ASTM D-1238 (190° C, loading of 2.16 kg). In embodiments, the ethylene-based polymer may comprise a melt index of from 0.05 to 4.0 dg / 10 min, from 0.05 to 3 dg / 10 min, or from 0.05 to 2.5 dg / 10 min. In further embodiments, the ethylene-based polymer may comprise a density from 0.850 to 0.950 g / cc, from 0.875 to 0.925 g / cc, from 0.890 to 0.920 g / cc.

[0032] In embodiments, the formulations described herein may comprise greater than 90 wt.%, greater than 92 wt.%, greater than 95 wt.%, greater than 97 wt.%, greater than 98 wt.%, or even greater than 99 wt.% ethylene-based polymer, based on the total weight of the formulation. In other embodiments, the formulations described herein may comprise less than 100 wt.%, less than 98 wt.%, less than 97 wt.%, less than 95 wt.%, less than 92 wt.%, or even less than 91 wt.% ethylene-based polymer, based on the total weight of the formulation. In one or more embodiments, the dimer acid may comprise less than or equal to 10 wt.% based on the total weight of the formulation. In specific embodiments, the dimer acid salts may be present in formulation from a minimum of 0.001 wt.%, 0.01 wt.%, 0.1 wt.%, 1 wt.%, 2 wt.%, or 5 wt.% to a maximum of 0.1 wt.%, 0.5 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 10 wt.% based on the total weight of the formulation.

[0033] In various embodiments, the formulation is used to reduce or completely eliminate melt fracture during extrusion. The polymer processing aid (PPA), i.e., the dimer acid may be delivered in many forms, for example, PPA masterbatch, or as liquid.

[0034] Further optional additives are contemplated for the PPA and / or the formulation encompassing the PPA. Non limiting examples of suitable other additives include antioxidants, antistatic agents, stabilizing agents, nucleating agents, colorants, pigments, ultraviolet (UV) absorbers or stabilizers, flame retardants, compatibilizers, plasticizers, fdlers, processing aids, antifog additive, crosslinking agents (e.g., peroxides), and combinations thereof.

[0035] Various process procedures are considered suitable for producing the formulations. For example, it is contemplated to add the components in various orders. In some embodiments, the dimer acid may be directly added as a liquid into the ethylene-based polymer. In one or more embodiments, the dimer acid may be added to the ethylene -based polymer via a masterbatch. In embodiments, generating a masterbatch may comprise compounding a polyethylene resin with the dimer acid. The masterbatch may be combined with a base resin to reduce melt fracture in the base resin in an extruder to fabricate a finished article. The base resin may include ethylene-based polymer, for example, FFDPE, FDPE, HDPE, or combinations thereof.

[0036] TEST METHODS

[0037] Density measurements were made in accordance with ASTM D792, Method B.

[0038] Melt Index (190 °C, 2.16 kg, “fc”) Test Method: ASTM D 1238-13, Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer, using conditions of 190 °C and a loading of 2.16 kilograms (kg). Results were reported in units of grams eluted per 10 minutes (dg / 10 min).EXAMPLES

[0039] The following examples are offered by way of illustration and are presented in a manner such that one skilled in the art should recognize are not meant to be limiting to the present disclosure as a whole or to the appended claims.

[0040] The following compositions were used in the Examples below.

[0041] All solvents including methyl isobutyl ketone and toluene are commercially available from Sigma-Aldrich.

[0042] The LLDPE Resin used as the base resin and as the PPA masterbatch carrier for the inventive examples had a melt index (I2) of 2.3 dg / 10 min and a density of 0.917 g / cc.

[0043] The dimer acid (also commercially available from Cargill) was obtained from Sigma Aldrich and is a hydrogenated dimer acid having a CAS Number of 68783-41-5. The hydrogenated dimer acid comprises greater than 98.0 % Dimer and less than 2 % trimer with small amount of monomeric fatty acids (about 1 wt.% or less).

[0044] Dynamar™ FX 5920 A is a fluoropolymer based PPA masterbatch available from 3M™.

[0045] Production of Dry Blended Inventive Examples IE1-IE2

[0046] Using a syringe, an amount of dimer acid was added to the polyethylene carrier resin (FFDPE) followed by tumbling of the pellets for 5 minutes.

[0047] Production of PPA Masterbatch Inventive Examples IE3-IE5

[0048] Masterbatches were made in a Micro 18 Twin Screw Extruder from Haake. The EEDPE base resin was fed into the main extruder dry-blended together with 4% of the dimer acid and together was fed into the main extruder. The flow rate was 10 Ibs / hr. The polymer melt was extruded using a Single Plate Die and was pelletized using MAAG GAEA Underwater Pelletizer. The process conditions are presented in Table 1.Table 1: Masterbatch Production Process Conditions

[0049] Melt Fracture Screening Method

[0050] Referring to the extruder conditions of Table 1 below, the base TTDPE resin was extruded via a single screw extruder into a 2 mm diameter capillary die. The flow rate was 0.5 kg / hr, which at a melt temperature of 212 °C, translates approximately to a shear rate of about 269 s'1. The resulting extrudate had melt fracture. After that, the PPA was introduced at loading levels listed in Table 3.Table 2: Extruder Conditions used in Melt Fracture Screening

[0051] A timer was started when each formulation was introduced in the extruder after the process was stabilized. If melt fracture was not cleared after a maximum observable timeframe of 120 minutes, the timer was stopped. The time to clear melt fracture, concentration of the PPA added and peak temperature is shown in Table 3. After every formulation, the extruder was purged with the base resin until the melt fracture was fully re-established; confirmed visually as well by the stabilization of the processing conditions (extruder torque, pressure).Table 3: Concentration of PPA, Peak Temperature, Amperage, and Time to Clear Melt Fracture

[0052] As shown in Table 3, sample CE1, which contained fluoropolymer, cleared the melt fracture in 34 minutes. In contrast, samples IE1-IE5, which contain the dimer acid, exemplified better performance than CE1 for the time needed to clear melt fracture even at much lower loadings. Furthermore, peak temperature and amperage decrease, which results in energy savings for customer and reduction of gels and cross-linking because of lower processing temperature. This is particularly notable, as samples IE1-IE5 contained notably lower amounts of PPA than CEE

[0053] The subject matter of the present disclosure has been described in detail and by reference to specific embodiments. It should be understood that any detailed description of a component or feature of an embodiment does not necessarily imply that the component or feature is essential to the particular embodiment or to any other embodiment. Further, it should be apparent to those skilled in the art that various modifications and variations can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

[0054] It is noted that one or more of the following claims utilize the term “wherein” as a transitional phrase. For the purposes of defining the present technology, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce arecitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.”

[0055] It is also noted that recitations herein of “at least one” component, element, etc., should not be used to create an inference that the alternative use of the articles “a” or “an” should be limited to a single component, element, etc.

Claims

CLAIMS1. A formulation comprising: at least 90 wt.% ethylene-based polymer; and dimer acid.

2. The formulation of claim 1, wherein the dimer acid comprises the structure of Formula(I), Formula (II), Formula (III), or mixtures thereof:Formula (I) Formula (II) Formula (III) whereinRi comprises a C4-C12 alkyl or a C4-C12 alkenyl when R4 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid;R2 comprises a C4-C12 alkyl or a C4-C12 alkenyl when R3 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid;R3 comprises a C4-C12 alkyl or a C4-C12 alkenyl when R2 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid;R4 comprises a C4-C12 alkyl or a C4-C12 alkenyl when Ri comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; andRs and Re independently comprise a hydrogen, a C1-C12 alkyl, or a C1-C12 alkenyl.

3. The formulation of claim 2, wherein the dimer acid is in a mixture having a majority of the structure of Formula (I).

4. The formulation of claim 2, wherein the dimer acid is in a mixture having a majority of the structure of Formula (II).

5. The formulation of claim 2, wherein the dimer acid is in a mixture having a majority of the structure of Formula (I) and Formula (II).

6. The formulation of any preceding claim, further comprising trimer acid having the structure of Formula (IV), Formula (V), or mixtures thereof:Formula (IV) Formula (V) whereinRi comprises a C4-C12 alkyl or a C4-C12 alkenyl when R4 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid;R2 comprises a C4-C12 alkyl or a C4-C12 alkenyl when R3 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid;R3 comprises a C4-C12 alkyl or a C4-C12 alkenyl when R2 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid;R4 comprises a C4-C12 alkyl or a C4-C12 alkenyl when Ri comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid;Rs, Re, R9, and Rio independently comprise a hydrogen, a C1-C12 alkyl, or a C1-C12 alkenyl;R7 comprises a C4-C12 alkyl or a C4-C12 alkenyl when Rs comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid; andRs comprises a C4-C12 alkyl or a C4-C12 alkenyl when R7 comprises a C4-C12 alkyl with a terminal carboxylic acid or a C4-C12 alkenyl with a terminal carboxylic acid.

7. The formulation of claim 6, wherein the formulation comprises more dimer acid than trimer acid.

8. The formulation of any preceding claim, wherein the formulation is essentially free of fluoropolymer.

9. The formulation of any preceding claim, wherein the ethylene-based polymer comprises Linear Low Density Polyethylene (LLDPE), High Density Polyethylene (HDPE), or combinations thereof.

10. The formulation of any preceding claim, wherein the formulation is a polymer processing aid masterbatch.

11. The formulation of any preceding claim, wherein the formulation is a pellet.

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