Ionomer dispersants for preparing aqueous polyolefin dispersions

Abstract

A method for preparing an aqueous polyolefin dispersion includes providing a partially neutralized ionomer dispersant, the ionomer dispersant being an ethylene acid copolymer comprising the polymerization reaction product of 70 to 85 weight percent ethylene and 15 to 30 weight percent carboxylic acid-containing comonomer, based on the total weight of monomers present in the ethylene acid copolymer, and 0.01 to 30 mole percent of the acid units of the ethylene acid copolymer, based on the total weight of monomers present in the ethylene acid copolymer, neutralized with alkali metal cations. The method further includes melt-blending the partially neutralized ionomer dispersant with a polyolefin to form a polymer melt mixture, emulsifying the polymer melt mixture in the presence of water and additional base to form an emulsion, wherein the additional base further neutralizes some or all of the remaining acid units, and diluting the emulsion with additional water to form the aqueous polyolefin dispersion.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority under 35 U.S.C. § 119 to U.S. Patent No. 63 / 399,869, filed August 22, 2022, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE INVENTION The embodiments disclosed in this application relate generally to methods for preparing aqueous polyolefin dispersions, and specifically to aqueous polyolefin dispersions comprising an ionomeric dispersant. [Background technology]

[0003] Ethylene acrylic acid (EAA) and ethylene methacrylic acid (EMAA) copolymers are commonly used as dispersants in the preparation of dispersions of various polyolefin polymers. When used in such dispersions, EAA / EMAA copolymers generally cannot achieve stable dispersions of polyolefin resins, especially when the AA or MAA content in the dispersant resin is low or the molecular weight is high.

[0004] Thus, there is a continuing need for improved EAA or EMAA dispersants for preparing processable and stable aqueous dispersions of polyolefins. Summary of the Invention

[0005] Embodiments of the present application fill a need for improving aqueous polyolefin dispersions by blending a base polyolefin with an EAA or EMAA copolymer that has been partially neutralized with an alkali metal cation (e.g., sodium) to form a partially neutralized ionomer, and then further neutralizing the partially neutralized ionomer with a base during emulsification. Without being limited by theory, these ionomers that have been partially neutralized with an alkali metal cation (e.g., sodium) provide a good balance of viscosity and hydrophilicity, which aids in the processability and stability of aqueous polyolefin dispersions.

[0006] According to one or more embodiments of the present application, there is provided a method for preparing an aqueous polyolefin dispersion. The method includes providing a partially neutralized ionomer dispersant comprising an ethylene acid copolymer, the ethylene acid copolymer comprising the polymerization reaction product of 70 to 85 weight percent ethylene and 15 to 30 weight percent carboxylic acid-containing comonomer units, based on the total weight of monomers present in the ethylene acid copolymer, wherein 0.01 to 30 mole percent of the acid units of the ethylene acid copolymer are neutralized with an alkali metal cation. The method further includes melt-blending the partially neutralized ionomer dispersant with one or more polyolefins to form a polymer melt mixture; emulsifying the polymer melt mixture in the presence of water and additional base to form an emulsion, wherein the additional base further neutralizes some or all of the remaining acid units of the partially neutralized ionomer; and diluting the emulsion with additional water to form an aqueous polyolefin dispersion.

[0007] It should 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 features of the claimed subject matter. Additional features and advantages of the embodiments are set forth in the detailed description, and in part will become readily apparent to those skilled in the art from that description, including the accompanying drawings and claims, or can be learned by practicing the described embodiments. The drawings are included to provide a further understanding of the embodiments and, together with the detailed description, serve to explain the principles and operation of the claimed subject matter. The embodiments, however, are illustrative and exemplary in nature and are not intended to be limiting of the claimed subject matter. [Brief explanation of the drawings]

[0008] [Figure 1] 10 is a graph showing calculation of the workability coefficient according to Example 2 of the present invention. [Figure 2] 10 is a graph showing calculation of the workability coefficient according to Example 6 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Certain embodiments of the present application will now be described. These embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art.

[0010] The term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Thus, the generic term polymer generally encompasses the term "homopolymer," which refers to a polymer prepared from only one type of monomer, as well as the term "copolymer," which refers to a polymer prepared from two or more different monomers. As used herein, the term "interpolymer" refers to a polymer prepared by polymerization of at least two different types of monomer. Thus, the generic term interpolymer includes copolymers or polymers prepared from more than two different types of monomers, such as terpolymers.

[0011] "Polyethylene" or "ethylene-based polymer" means a polymer containing more than 50 mole percent units derived from ethylene monomers. This includes ethylene-based homopolymers or copolymers (meaning the units are derived from two or more comonomers). Common forms of ethylene-based polymers known in the art include, but are not limited to, 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 (m-LLDPE), including both linear and substantially linear low-density resins, medium-density polyethylene (MDPE), and high-density polyethylene (HDPE).

[0012] "Polypropylene" or "propylene-based polymer" means a polymer containing greater than 50 mole percent units derived from propylene monomers. This includes propylene-based homopolymers or copolymers (meaning the units are derived from two or more comonomers). Common forms of propylene-based polymers known in the art include, but are not limited to, impact polypropylene copolymer (icPP), random copolymer (rcPP), polypropylene homopolymer (hPP), propylene-ethylene copolymer (POE plastomer), and polypropylene reactor blends.

[0013] "Ethylene acid copolymer" is the polymerization reaction product of ethylene and one or more unsaturated carboxylic acids.

[0014] As used herein, "dispersion" and related terms refer to solid particles, such as polymer particles, suspended in an aqueous liquid phase. Additionally, as used herein, "dispersant" refers to a composition used to maintain the suspension of polymer particles in the aqueous liquid phase.

[0015] Embodiments of the present application relate to a system and method for producing an aqueous polyolefin dispersion by utilizing a partially neutralized ionomer dispersant comprising an ethylene acid copolymer, the ethylene acid copolymer comprising the polymerization reaction product of 70-85 wt. % ethylene and 15-30 wt. % carboxylic acid-containing comonomer, based on the total weight of the monomers present in the ethylene acid copolymer, wherein 0.01-30 mol. % of the acid units of the ethylene acid copolymer are neutralized with alkali metal cations. The partially neutralized ionomer dispersant and one or more polyolefins are melt-blended to produce a polymer melt mixture, which is then emulsified in the presence of water and additional base to produce an emulsion, where the additional base further neutralizes the acid units of the partially neutralized ionomer. The emulsion is then diluted with additional water to produce the aqueous polyolefin dispersion.

[0016] Aqueous Polyolefin Dispersion In embodiments of the present application, the aqueous polyolefin dispersion may have smaller particle sizes and better dispersion quality. All individual values ​​and subranges are included and disclosed herein. As used herein, the total resin solids content is comprised of the ionomer, polyolefin, and, optionally, some alkali metal cation-containing base. Without being limited by theory, the present system and method, particularly the ionomer partially neutralized by the alkali metal added to the polymer mixture, may ensure a balance of melt viscosity within the base resin or more efficient neutralization, which may result in smaller particle sizes and better dispersion quality since some neutralization may already have occurred. The total resin solids content may be 5 to 50 wt. % ionomer and 50 to 95 wt. % polyolefin.

[0017] The particles present in the aqueous polyolefin dispersion may have an average particle size of 2.00 μm or less, or less than 1.50 μm. All individual values ​​and subranges are included and disclosed herein. For example, the aqueous polyolefin dispersion may have an average particle size of 0.1-1.50 μm, 0.50-1.50 μm, 0.75-1.50 μm, 0.80-1.40 μm, or 0.80-1.30 μm. Without being limited by theory, at particle sizes greater than 2.0 μm, the particles tend not to maintain colloidal stability, i.e., remain suspended in the aqueous phase, and at average particle sizes of 1.50 μm or less, colloidal stability tends to be improved.

[0018] Ionomer Dispersants Ionomers are ethylene acid copolymers partially neutralized with alkali metal cations. The ethylene acid copolymer is the polymerization reaction product of 70-85 wt% ethylene and 15-30 wt% carboxylic acid-containing comonomer, based on the total weight of monomers present in the ethylene acid copolymer. All individual values ​​and ranges are included and disclosed herein. For example, in some embodiments, the ethylene acid copolymer is the polymerization reaction product of 72-85 wt% ethylene and 15-28 wt% carboxylic acid-containing comonomer, based on the total weight of monomers present in the ethylene acid copolymer. In another embodiment, the ethylene acid copolymer is the polymerization reaction product of 75-85 wt% ethylene and 15-25 wt% carboxylic acid-containing comonomer, based on the total weight of monomers present in the ethylene acid copolymer. In a further embodiment, the ethylene acid copolymer is the polymerization reaction product of 79-82 wt% ethylene and 18-21 wt% carboxylic acid-containing comonomer, based on the total weight of monomers present in the ethylene acid copolymer. Ethylene acid copolymers may be polymerized according to the processes disclosed in U.S. Patent Nos. 3,404,134, 5,028,674, 6,500,888, and 6,518,365. In some embodiments, mixtures of two or more ethylene acid copolymers may be used, provided that the aggregate content and properties of the mixture fall within the ranges described above for the ethylene acid copolymers.

[0019] Various carboxylic acid-containing comonomers may be utilized in the ethylene acid copolymers. For example, the carboxylic acid-containing comonomers may include monocarboxylic acids containing acrylic acid, methacrylic acid, or both.

[0020] As noted above, the ethylene acid copolymer is already partially neutralized (forming an ionomer) with alkali metal cations when incorporated into the polymer melt mixture to prepare the dispersion. The calculation of the percent neutralization, referring to the total acid units neutralized, is based on the number of acid units believed to be present, the molar amount of the known carboxylic acid-containing comonomer, and the number of molar equivalents of the alkali metal added. In this embodiment, 0.01 mol% to 30 mol% of the total acid units of the ethylene acid copolymer are neutralized with alkali metal cations. All individual values ​​and subranges are included and disclosed herein. In further embodiments, 0.1 mol% to 30 mol%, 1 mol% to 30 mol%, 2 mol% to 30 mol%, 2 mol% to 20 mol%, or 5 mol% to 20 mol% of the total acid units may be neutralized in the ionomer partial neutralization step. Without being limited by theory, partial neutralization to an amount greater than 30 mol% may undesirably increase the melt viscosity in the melt mixture, thereby reducing processability. In some embodiments, neutralization levels of 20% or less may be maintained to ensure processability.

[0021] Exemplary alkali metal cations for partial neutralization include, but are not limited to, sodium, potassium, and lithium, or combinations thereof. In some embodiments, the alkali metal cation is selected from the group consisting of sodium, potassium, and lithium, or combinations thereof. In certain embodiments, the alkali metal cation is sodium.

[0022] Prior to partial neutralization, the melt index (I2) of the ethylene acid copolymer, as measured according to ASTM D1238 (190°C, 2.16 kg), is in the range of 75 to 1000 g / 10 min. In other embodiments, the melt index of the ethylene acid copolymer may be in the range of 150 to 900 g / 10 min, 175 to 600 g / 10 min, 200 to 400 g / 10 min, or 275 to 325 g / 10 min. All individual values ​​and subranges are included within this application.

[0023] After partial neutralization, the partially neutralized ionomer may have a melt index (I2) of 35 to 750 g / 10 minutes. All individual values ​​and subranges are included and disclosed herein. For example, in some embodiments, the ionomer may have a melt index (I2) of 40 to 250 g / 10 minutes, 40 to 100 g / 10 minutes, 60 to 250 g / 10 minutes, or 60 to 100 g / 10 minutes.

[0024] Polyolefin As described above, the aqueous polyolefin dispersions described herein include a polyolefin. The polyolefin may be selected from the group consisting of polyethylene or polypropylene or copolymers thereof. In one embodiment, the polyolefin includes polypropylene. In another embodiment, the polyolefin includes a propylene / ethylene copolymer. The other comonomer may include butene, hexene, or octene.

[0025] A variety of densities are contemplated as suitable for polyolefins. In some embodiments described herein, the polyolefins may have a density of 0.850 g / cc to 0.975 g / cc. All individual values ​​and subranges from at least 0.850 g / cc to 0.975 g / cc are included and disclosed herein. For example, in some embodiments, the polyolefins may have a density of 0.855 to 0.905 g / cc, 0.855 to 0.900 g / cc, 0.855 to 0.900 g / cc, or 0.865 to 0.895 g / cc. Density may be measured according to ASTM D792.

[0026] In one or more polypropylene embodiments, the melt flow rate may be less than 30 g / 10 min, less than 10 g / 10 min, or less than 6 g / 10 min, as measured according to ASTM D-1238, Procedure B (230°C / 2.16 kg condition). In further embodiments, the polypropylene may have a melt flow rate of 0.5 to 75 g / 10 min, 1.0 to 50 g / 10 min, 2.0 to 25.0 g / 10 min, 5.0 to 15.0 g / 10 min, or 7 to 10.0 g / 10 min. In one or more polyethylene embodiments, the polyethylene may have a melt index (I2) of 0.1 to 100 g / 10 min, 0.5 to 75 g / 10 min, 1.0 to 50 g / 10 min, 2.0 to 25.0 g / 10 min, 2.5 to 10.0 g / 10 min, or 2.5 to 7.5 g / 10 min, as measured in accordance with ASTM D-1238, Procedure B (190°C / 2.16 kg condition). All individual values ​​and subranges are disclosed herein.

[0027] Additional additives The aqueous polyolefin dispersion may contain any other additives known in the art. Examples of additives include, but are not limited to, antioxidants, processing aids, flow-improving additives, lubricants, pigments, dyes, flame retardants, impact modifiers, nucleating agents, antiblocking agents such as silica, heat stabilizers, UV absorbers, UV stabilizers, surfactants, chelating agents, and coupling agents. The additives may be used in an amount ranging from 0.0001 to 5 wt % based on the total weight of the total resin solids content in the aqueous polyolefin dispersion.

[0028] method As described above, the partially neutralized ionomer dispersant and one or more polyolefins are melt mixed to form a polymer melt mixture, which is then emulsified in the presence of water and additional base to form an emulsion. During emulsification, the additional base further neutralizes the acid units of the partially neutralized ionomer. A variety of bases are considered suitable for the neutralization step. In one embodiment, the base is an inorganic base such as potassium hydroxide or sodium hydroxide. Organic bases such as amines and ammonia are also suitable. In embodiments, the additional base may comprise multiple bases or a single base. The mixing of the polymer melt mixture with water and base is carried out at a temperature of 100°C to 250°C. A further optional step after dilution may include cooling the heated aqueous polyolefin dispersion to a temperature of 20°C to 30°C, while the ionomer remains dispersed in the liquid phase. The emulsion is then diluted with additional water to form the aqueous polyolefin dispersion.

[0029] Purpose The aqueous polyolefin dispersions described herein may be used to coat substrates such as floors, plastic parts, wood, textiles, metal, ceramic, fiber, glass, or paper. Suitable substrates may include paperboard, cardboard, pulp-molded shapes, woven fabrics, nonwoven fabrics, films, open-cell foams, closed-cell foams, or metal foils. In some embodiments of the present application, a method for coating a substrate includes preparing an aqueous polyolefin dispersion described in an embodiment of the present application and applying the aqueous polyolefin dispersion to the substrate to form a coated substrate. Application may be carried out by dipping, spraying, roll coating, doctor blade coating, flow coating, or other suitable methods for applying liquid coatings known in the art. The method may further include a drying step.

[0030] In another embodiment of the present application, a method of forming a coated article includes coating a substrate with an aqueous polyolefin dispersion described in one or more embodiments of the present application to form a coated substrate, and drying the coated substrate to form the coated article.

[0031] Aqueous polyolefin dispersions can be used in a variety of applications, such as water barrier applications, gas barrier applications, oil and fat barrier coatings, heat seal coatings, and artificial turf.

[0032] Test Method density Density is measured according to ASTM D-792 and is reported in grams per cubic centimeter (g / cc).

[0033] Melt Index (I2) For ethylene-based polymers, melt index (I2) was measured in accordance with ASTM D-1238, Procedure B (Condition 190°C / 2.16 kg) and is reported in grams dissolved per 10 minutes (g / 10 min).

[0034] Melt Flow Rate For propylene-based polymers, melt flow rate was measured according to ASTM D-1238, Procedure B (condition 230°C / 2.16 kg) and is reported in grams extracted per 10 minutes (g / 10 min).

[0035] Average particle size The mean particle size is defined as the volume-average particle size measured with a Beckman Coulter LS 13-320 laser light scattering particle sizer (Beckman Coulter Inc., Fullerton, California) using an epoxy particle model (real fluid refractive index = 1.332, real sample refractive index = 1.5, virtual sample refractive index = 0). Samples are diluted in a KOH solution with a pH > 10 before measurement.

[0036] Dynamic Viscosity Dynamic viscosity is measured by a Brookfield DV-II+ viscometer with an RV3 spindle. Approximately 0.5 mL of the dispersion is loaded into the device and measured at the appropriate rpm to obtain a steady viscosity value for 15 seconds, after which the dynamic viscosity is recorded.

[0037] Workability coefficient The processability factor is defined by plotting a curve of particle size (y-axis) versus the initial aqueous solution / polymer ratio (x-axis) for a 15% dispersant, and then calculating the width of the curve where the particle size is less than 1.75 microns. This is calculated by subtracting the lowest measurement on the x-axis of the graph where the particle size on the y-axis of the graph is less than 1.75 microns from the highest measurement on the x-axis of the graph where the particle size on the y-axis of the graph is less than 1.75 microns. To illustrate how the calculation is performed, Figures 1 and 2 are provided, which are plots of particle size versus the initial aqueous solution / polymer ratio for Examples 2 and 6 of the present invention, respectively. The data for Figures 1 and 2 are set forth below in Tables 1 and 2, respectively.

[0038] [Table 1]

[0039] [Table 2] [Example]

[0040] The dispersants were prepared by two methods. Ionomers 2-9 were prepared by first preparing an ethylene acid copolymer by peroxide-initiated free radical polymerization as described below, followed by conversion to an ionomer by compounding sodium carbonate (NaCO) in an extruder. The extrusion process was carried out in two steps using a 26 mm twin-screw extruder with a feed rate of 15 lbs / h and a screw speed of 400 RPM. The barrel temperature was set at 230°C, and a vacuum of 20 inHg was drawn through an exhaust port located after the mixing section. In the first extrusion step, a concentrated resin with a melt index of approximately 10 g / 10 min (190°C, 2.16 kg) was prepared by separately feeding the ethylene acid copolymer and sodium carbonate in the desired ratio into the extruder hopper using a gravimetric feeder. In the second extrusion step, the final ionomer with the weighted average neutralization level shown in Table 3 was prepared by dry-blending the concentrated resin with pure ethylene acid copolymer resin and then feeding it into the extruder hopper using a gravimetric feeder. The extrudate is cooled by passing through a water bath and pelletized using a strand cutter.

[0041] Ionomer Dispersant Blends 10-14 were prepared by melt blending unneutralized ethylene acid copolymer (Acid Copolymer 17) with sodium ionomer (Ionomer 15) to form an ionomer with a weighted average neutralization level. The blended samples were prepared in a 35mm twin-screw extruder with a feed rate of 50 lbs / h and a screw speed of 300 RPM. The barrel temperature was set at 200°C, and a vacuum of 20 inHg was drawn through an exhaust port located after the mixing section. The unneutralized acid copolymer and sodium ionomer were fed separately into the extruder hopper using gravimetric feeders. The extrudate was cooled by passing through a water bath and pelletized using a strand cutter.

[0042] An example of an aqueous polyolefin dispersion is prepared using a Berstorf (KraussMaffei) twin-screw extruder with 48 L / D and a 25 mm screw diameter. The polyolefin resin (VERSIFY™ 3200) and the partially neutralized ionomer dispersant in Table 1 are fed into the extruder feed throat via a Schneck Mechatron loss-in-weight feeder and a K-Tron pellet feeder, respectively. The ionomer dispersant is already partially neutralized with sodium cations. The polyolefin resin and the partially neutralized ionomer dispersant are melt mixed to form a polymer melt mixture. The polymer melt mixture is then emulsified in the presence of an initial aqueous solution stream and further neutralized with additional base (KOH) to form an emulsion phase. The initial aqueous solution feed and additional base are fed at the rates shown in Table 4 and injected using an ISCO syringe pump (Teledyne Isco, Inc., Lincoln, NE, USA). The emulsion phase is then conveyed to the dilution and cooling zone of the extruder, where additional dilution water is added to the emulsion via an ISCO dual syringe pump at the rate shown in Table 4 to form an aqueous polyolefin dispersion having the solids level content shown in Table 5. The extruder barrel temperature is set at 150°C, and the extruder speed is 450 rpm. After exiting the extruder, the dispersion is allowed to cool to room temperature and then filtered through a bag filter with a 200 μm mesh size. The example aqueous polyolefin dispersion had a final neutralization of 85 mole % of the acid groups. Additionally, the example aqueous polyolefin dispersion contains 85 weight % polyolefin and 15 weight % ionomer based on the total solids content as shown in Table 5.

[0043] Ethylene acid copolymers are prepared by standard free-radical copolymerization techniques carried out continuously under high pressure. Monomers are fed to the reaction mixture in proportions related to the reactivity of the monomers and the desired incorporation. In this manner, a uniform, nearly random distribution of monomer units along the chain is achieved. Polymerization in this manner is well known and is described in U.S. Pat. No. 4,351,931 (Armitage), which is incorporated herein by reference. Other polymerization techniques are described in U.S. Pat. No. 5,028,674 (Hatch et al.) and U.S. Pat. No. 5,057,593 (Statz), both of which are incorporated herein by reference. Additional aspects of the ionomers are shown in Table 1 below. These acid copolymer ionomers are prepared as described above.

[0044] VERSIFY™ 3200 from Dow Inc., Midland, MI is a plastomer with a density of 0.876 g / cc and a melt flow rate of 8 g / 10 min according to ASTM D1238 (230° C. / 2.16 kg).

[0045] PRIMACOR™ 5980i from SK Chemicals is an ethylene acrylic acid copolymer with a density of 0.958 g / cc and a melt index (I2) of 300 g / 10 min according to ASTM D1238 (@190° C. / 2.16 kg).

[0046] [Table 3]

[0047] [Table 4]

[0048] [Table 5]

[0049] In Table 5, samples that formed dispersions with undesirable phase separation are indicated with a "YES" in the Phase Separation column, while samples that did not are indicated with a "NO." Additionally, samples that stably formed processable dispersions are indicated as having a processability factor greater than 0. Those that were not processable are indicated as "Not Processable." A processability factor of 0 means that a dispersion could be formed, but only under one test condition of initial aqueous solution to polymer ratio, indicating that the dispersion was not stable to different processing conditions.

[0050] As shown in the dispersion results in Table 5 above, Comparative Example 1, which was not partially neutralized before being melt-blended with the polyolefin, does not form an aqueous polyolefin dispersion with a high processability factor. A high processability factor, also representing a wide processability window, indicates that stable dispersions with small particle sizes are formed using a wide range of initial aqueous solution / polymer ratios, rather than only at one specific ratio. This is an indication that this formulation is more tolerant to minor variations in processing. Comparative Examples 1, 4, 16, and 17, in which the ionomer dispersant was not partially neutralized before being melt-blended with the polyolefin, result in low processability factors, or, in the case of Comparative Example 4, phase separation. Comparative Example 4 is processable (since its processability factor is greater than 0), but exhibits phase separation. Comparative Examples 1, 16, and 17 do not have high processability factors. Also, as shown in Tables 3 and 5, Comparative Example 14, with a melt index of 33 g / 10 min, results in a low processability factor. Comparative Example 15, which contains 49% acid groups that are initially neutralized, is unprocessable. All of the inventive examples contain neutralized acid groups in an amount ranging from about 0.01 mol % to 30 mol %. All of the inventive examples are processable, exhibit no phase separation, and form dispersions containing 30-60 wt % solids, containing fine particles with an average particle size of less than 2 μm, and exhibiting high processability factors greater than 0.04.

[0051] It will be apparent to those skilled in the art that various modifications and variations are possible without departing from the scope of the present application. Modifications, combinations, subcombinations, and variations of the disclosed embodiments that incorporate the spirit and substance of the present application may occur to those skilled in the art, and therefore the scope of the present application should be interpreted as including all within the scope of the appended claims and their equivalents.

[0052] For purposes of defining the present technology, the transitional phrase "consisting of" may be introduced in a claim as a closed preamble term limiting the claim to the recited components or steps and any naturally occurring impurities. For purposes of defining the present technology, the transitional phrase "consisting essentially of" may be introduced in a claim to limit one or more claims to the recited elements, components, materials, or method steps and any unrecited elements, components, materials, or method steps that do not materially affect the novel characteristics of the claimed subject matter. The transitional phrases "consisting of" and "consisting essentially of" can be interpreted as subsets of open-ended transitional phrases such as "comprising" and "including," such that any use of an open-ended phrase to introduce a recitation of a series of elements, components, materials, or steps should be interpreted as also disclosing the recitation of that series of elements, components, materials, or steps using the closed terms "consisting of" and "consisting essentially of." For example, a description of a composition "comprising" components A, B, and C should be interpreted as also disclosing compositions "consisting of" components A, B, and C, as well as compositions "consisting essentially of" components A, B, and C. Any quantitative values ​​expressed in this application may be considered to include open-ended embodiments consistent with the transitional phrases "comprising" or "including," as well as closed or partially closed embodiments consistent with the transitional phrases "consisting of" and "consisting essentially of."

[0053] As used in this application and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The verb "comprises" and its conjugations should be construed as a non-exclusive reference to elements, components, or steps. A referenced element, component, or step may be present in, utilized with, or combined with other elements, components, or steps not expressly referenced.

[0054] It should be understood that any two quantitative values ​​assigned to a characteristic may constitute a range for that characteristic, and that all combinations of ranges formed from all stated quantitative values ​​for a given characteristic are contemplated in this application. The subject matter of this application has been described in detail with reference to specific embodiments. It should be understood that any detailed description of an element or feature of an embodiment does not necessarily imply that the element or feature is essential to the particular embodiment or any other embodiment. Furthermore, it will 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.

Claims

1. A method for preparing an aqueous polyolefin dispersion, A step to provide a partially neutralized ionomer dispersant containing an ethylene acid copolymer, wherein the ethylene acid copolymer contains a polymerization reaction product of 70 to 85% by weight of ethylene and 15 to 30% by weight of carboxylic acid-containing comonomers, based on the total weight of monomers present in the ethylene acid copolymer, and 0.01 to 30 mol% of the total acid units of the ethylene acid copolymer are neutralized by alkali metal cations. The partially neutralized ionomer dispersant is melt-mixed with one or more polyolefins to produce a polymer melt mixture. The polymer molten mixture is emulsified in the presence of water and an additional base to produce an emulsion, wherein the additional base further neutralizes some or all of the remaining acid units of the partially neutralized ionomer. A method comprising diluting the emulsion with additional water to produce an aqueous polyolefin dispersion.

2. The method according to claim 1, wherein the carboxylic acid-containing comonomer comprises methacrylic acid, acrylic acid, or a combination thereof.

3. The method according to claim 1, wherein the melting and mixing and emulsification are carried out at a temperature of 100 to 250°C.

4. The method according to claim 1, wherein the aqueous polyolefin dispersion contains 30 to 60% by weight of total solids.

5. The method according to claim 4, wherein the total solid content has an average particle diameter of 2 μm or less.

6. The method according to claim 1, wherein the alkali metal includes sodium.

7. The method according to claim 1, wherein the additional base comprises KOH.

8. The melt index (I) of the partially neutralized ionomer dispersant was measured according to ASTM D1238 (190°C, 2.16 kg). ２ The method according to claim 1, wherein the amount is 35 to 750 g / 10 min, or 60 to 250 g / 10 min.

9. When measured according to ASTM D1238 (190°C, 2.16 kg), the melt index (I) of the ethylene acid copolymer before neutralization was ２ The method according to claim 1, wherein the amount is 100 to 1000 g / 10 min, or 200 to 400 g / 10 min.

10. The method according to claim 1, wherein the partially neutralized ionomer dispersant contains total acid units neutralized by alkali metal cations in amounts of 0.1 mol% to 30 mol%, 1 mol% to 30 mol%, 2 mol% to 30 mol%, 2 to 20 mol%, or 5 to 20 mol%.

11. The aforementioned polyolefin, when measured according to ASTM D1238 (190°C, 2.16 kg), has a melt index (I) of 0.1 to 100.0 g / 10 min. ２ The method according to claim 1, comprising an ethylene / α-olefin copolymer having ).

12. The method according to claim 1, wherein the polyolefin comprises a propylene / ethylene copolymer having a melt flow rate of 0.5 to 75 g / 10 min when measured according to ASTM D-1238, Procedure B (under conditions of 230°C / 2.16 kg).

13. The method according to claim 1, wherein the polyolefin is selected from the group consisting of polyethylene and polypropylene.

14. An aqueous polyolefin dispersion prepared by the method described in any one of claims 1 to 13.

15. A coated article prepared with the aqueous polyolefin dispersion according to claim 14.

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