Polyolefin composition

Abstract

A polymer blend may be formed by melt blending a polyolefin polymer with an amount of a polyacid polymer and a polyol under conditions such that acid groups on the polyacid polymer react with hydroxyl groups on the polyol to form a linkage between the polyacid polymer and the polyol. The condensation product polymer can improve the physical properties of the polyolefin polymer.

Description

Polyolefin compositions Technical Field

[0001] This application relates to the field of polyolefin compositions. Background Technology

[0002] Polyolefins include homopolymers and copolymers of polyethylene and polypropylene. Polyolefins are widely used in molded and extruded products. A common application of polyolefins is in extruded films for various packaging applications.

[0003] Polyolefins can offer a good combination of physical properties and chemical stability at low cost. Specifically, the physical properties of polyolefins can be tuned to match the requirements of specific applications by selecting and proportioning monomers, controlling molecular weight profiles, and controlling branching.

[0004] In some cases, different polymers are blended into polyolefins to modulate the properties of the polyolefin. However, blending polymers with polyolefins can introduce new problems. Compatibility issues between the polyolefin and the added polymer can cause phase separation, which may impair the physical properties of the polymer blend. Furthermore, blending other polymers with polyolefins can increase the cost of the polymer blend. The polymer blended with the polyolefin may be more expensive than the polyolefin itself, and the blending process may add additional processing steps with additional costs.

[0005] The aim is to identify blends of polyolefins with other polymers that can be easily formed using only small amounts of the added polymers and with minimal additional processing costs, thus improving the properties of the polyolefins. Summary of the Invention

[0006] A first aspect of the present invention is a polyolefin composition comprising:

[0007] a) At least 50% by weight of polyolefin polymer;

[0008] b) At least 100 ppmw of polybasic acid polymers, and

[0009] c) At least 20 ppmw of a polyol capable of reacting with the polyacid polymer to form an ester crosslink.

[0010] The weight ratio is based on the combined weight of the polyolefin polymer, the polyacid polymer, and the polyol.

[0011] A second aspect of the invention is a method for preparing a polymer blend, the method comprising the step of melt-blending the polyolefin composition of the first aspect of the invention under conditions in which the polyacid polymer and the polyol undergo a condensation reaction to form ester groups linking the polyacid polymer and the polyol. The method prepares a polymer blend comprising a polyolefin polymer and a condensation product formed by the condensation of the polyacid polymer and the polyol, the condensation product being dispersed within the polyolefin polymer.

[0012] A third aspect of the present invention is a polymer blend comprising:

[0013] a) At least 50% by weight of polyolefin polymer;

[0014] b) At least 150 ppm of a condensation product formed by the condensation of a polyacid polymer and a polyol, the condensation product being dispersed within the polyolefin polymer.

[0015] These weight ratios are based on the combined weight of the polyolefin polymer and the condensation product.

[0016] A fourth aspect of the invention is a membrane comprising the polymer blend of the third aspect of the invention.

[0017] Unbound by theory, it is believed that the polyacid polymer and the polyol react to prepare a cross-linked polymer network, which forms a semi-interpenetrating polymer network (semi-IPN) within the polyolefin. Semi-interpenetrating polymer networks are known and described in numerous publications such as Sperling, “Interpenetrating Polymer Networks: An Overview” (American Chemical Society, 1994) and Kulkarni, “Interpenetrating Polymer Network – A Promising Method for Widening Applications of Polymers”, 7(4), International Journal of Research and Review 74 (April 2020). A semi-IPN contains a cross-linked network of one polymer and another non-cross-linked polymer, interwoven at the polymer molecular scale. Semi-IPNs are highly resistant to phase separation and therefore generally remain homogeneous.

[0018] During conventional extrusion of polyolefins, polyacid polymers and polyols can be blended and reacted with the polyolefin to form condensation products without any additional procedural steps. Therefore, the formation of polymer blends adds little to no additional processing costs. In some embodiments, the polymer blends exhibit physical improvements compared to polyolefins using only very small amounts of polyacid polymers and polyols (e.g., less than 1% by weight) and without compatibilizers. Therefore, the present invention adds almost no cost to polyolefins. Detailed Implementation

[0019] In this invention, as described in the first aspect, a polyacid polymer and a polyol are blended into a polyolefin polymer. The blend is subjected to conditions that induce condensation reactions, which link the polyacid polymer and the polyol. Examples of suitable conditions include the high temperature and high shear conditions for melt blending as described in the second aspect. As described in the third aspect, the condensation products of the polyacid polymer and the polyol form a polymer blend within the polyolefin polymer. As described in the fourth aspect, the polymer blend can be molded into articles such as films. Alternatively, a high concentration of the polyacid polymer and the polyol can be used to prepare the polymer blend to form a masterbatch, which is then granulated; subsequently, the masterbatch can be blended with more polyolefin to obtain a desired level of condensation product, and then molded or extruded for use.

[0020] The polyolefin composition comprises a polyolefin polymer, a polyacid polymer, and a polyol.

[0021] In some embodiments, the polyolefin polymer includes polyethylene. In some embodiments, the polyolefin polymer includes linear low-density polyethylene.

[0022] In some embodiments, the polyacid polymer comprises a copolymer containing repeating units derived from acrylic acid or methacrylic acid and repeating units derived from one or more comonomers selected from the group consisting of ethylene, propylene, and styrene. In some embodiments, the polyacid polymer is an ionic polymer. In other embodiments, the polyacid polymer is not an ionic polymer.

[0023] In some embodiments, the polyol comprises a copolymer containing repeating units of vinyl alcohol and repeating units derived from ethylene, propylene, or styrene. In some embodiments, the molar ratio of acid groups in the polyacid polymer to hydroxyl groups in the polyol is 5:1 to 1:5.

[0024] In some embodiments, the polyolefin polymer is a polyethylene polymer and comprises at least 75% by weight of the polyolefin composition; the polyacid polymer comprises a copolymer containing repeating units derived from acrylic acid or methacrylic acid and repeating units derived from ethylene; and the polyol comprises a copolymer containing repeating units of vinyl alcohol and repeating units derived from ethylene, wherein the molar ratio of acid groups in the polyacid polymer to hydroxyl groups in the polyol is 5:1 to 1:5, and wherein the weight ratio is based on the combined weight of the polyolefin polymer, the polyacid polymer, and the polyol. In some embodiments, the polyolefin composition comprises 75% to 98% by weight of the polyolefin polymer, 2% to 20% by weight of the polyacid polymer, and 1% to 10% by weight of the polyol, wherein the weight percentage is based on the combined weight of the polyolefin polymer, the polyacid polymer, and the polyol. In some embodiments, the polyolefin composition comprises: at least 98% by weight of the polyolefin polymer; 100 ppmw to 2000 ppmw of the polyacid polymer; and 50 ppmw to 1000 ppmw of the polyol, wherein the weight percentage is based on the combined weight of the polyolefin polymer, the polyacid polymer, and the polyol.

[0025] Polyolefin components

[0026] This invention uses polyolefin polymers. In some embodiments, the polyolefin polymer is a polyethylene polymer. In some embodiments, the polyolefin polymer is a polypropylene polymer. In some embodiments, the polyolefin polymer is an elastomer, while in others it is not an elastomer. The choice of polyolefin polymer can be highly dependent on the intended use of the polymer.

[0027] The polyethylene (PE) polymers used in this invention can be homopolymers or copolymers. PE homopolymers consist essentially of repeating units derived from ethylene, with no significant amount of repeating units derived from comonomers. PE copolymers comprise at least 70% by weight of repeating units derived from ethylene, but also contain repeating units derived from comonomers. Examples of suitable comonomers may include α-olefins. Suitable α-olefins may include α-olefins containing 3 to 20 carbon atoms (C3-C20). For example, α-olefins may be C4-C20 α-olefins, C4-C12 α-olefins, C3-C10 α-olefins, C3-C8 α-olefins, C4-C8 α-olefins, or C6-C8 α-olefins. In some embodiments, the α-olefin is selected from the group consisting of propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, and 1-decene. In other embodiments, the α-olefin is selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene. In yet another embodiment, the α-olefin is selected from the group consisting of 1-hexene and 1-octene.

[0028] Polyethylene polymers and copolymers are generally classified into the following groups:

[0029] • High-density polyethylene (HDPE), which typically has a density of approximately 0.93 g / cm³. 3 Up to 0.98 g / cm 3 The density;

[0030] • Low-density polyethylene (LDPE), which typically has a density of approximately 0.91 g / cm³. 3 Up to 0.93 g / cm 3 The density; and

[0031] • Linear low-density polyethylene (LLDPE), which typically has a density of approximately 0.91 g / cm³. 3 Up to 0.94 g / cm 3 The density.

[0032] Linear low-density polyethylene contains short-chain branching and fewer long-chain branching than LDPE, and includes substantially linear ethylene polymers, which are further described in U.S. Patents 5,272,236, 5,278,272, 5,582,923, and 5,733,155; homogeneously branched linear ethylene polymer compositions, such as those in U.S. Patent No. 3,645,992; heterogeneously branched ethylene polymers, such as those prepared according to the procedure disclosed in U.S. Patent No. 4,076,698; and / or blends thereof (such as those disclosed in U.S. 3,914,342 or U.S. 5,854,045).

[0033] In some embodiments, the polyethylene polymer of the present invention is HDPE. In some embodiments, the polyolefin polymer of the present invention is LDPE.

[0034] In some embodiments, the polyethylene polymer of the present invention has a content of 0.91 g / cm³. 3 Up to 0.94 g / cm 3 LLDPE with a density of 0.91 g / cm³ is included and disclosed herein. 3 Up to 0.94 g / cm 3 All individual values ​​and sub-ranges. For example, in some embodiments, the density is 0.910 g / cm³. 3 0.915g / cm 3 0.920g / cm 3 0.925g / cm 3 0.930g / cm 3 Or 0.935g / cm 3The lower limit is 0.940 g / cm³. 3 0.935g / cm 3 0.930g / cm 3 0.925g / cm 3 Or 0.920 g / cm 3 Within the upper limit range.

[0035] Polyethylene polymers are typically characterized by their melt index. In some embodiments, the melt index (I² - measured at 190°C / 2.16 kg) of the polyethylene polymer ranges from 0.01 g / 10 min to 30 g / 10 min. All individual values ​​and sub-ranges from 0.01 g / 10 min to 30 g / 10 min are included and disclosed herein. For example, in some embodiments, the melt index ranges from a lower limit of 0.01, 0.05, 0.1, 0.25, 0.5, 1, 3, 5, 7, 10, 12, 15, 18, 20, 23, or 25 to an upper limit of 30, 27, 25, 22, 20, 17, 15, 12, 10, 8, 5, 2, 1, 0.9, 0.7, or 0.5. In some embodiments, the polyethylene polymer used in membrane applications may have a melt index of at least 0.1 g / 10 min, at least 0.3 g / 10 min, at least 0.5 g / 10 min, at least 0.7 g / 10 min, or at least 0.8 g / 10 min. In some embodiments, the polyethylene polymer used in membrane applications may have a melt index of at most 10 g / 10 min, at most 8 g / 10 min, at most 6 g / 10 min, at most 4 g / 10 min, or at most 2 g / 10 min.

[0036] Suitable PE polymers can be such as DOW ™ LDPE, DOWLEX ™ ELITE ™ INNATE ™ and AFFINITY ™ Trademarked and available for purchase. Other PE polymers can be prepared by known processes, such as solution, slurry, and / or gas-phase polymerization of ethylene monomers and optionally comonomers in the presence of Ziegler-Natta catalysts, metallocene catalysts, or other single-point catalysts.

[0037] The polypropylene (PP) polymers used in this invention can be homopolymers, random copolymers, or impact copolymers. PP homopolymers consist essentially of repeating units derived from propylene, with no significant amount of repeating units derived from the comonomer. PP copolymers comprise at least 70% by weight of repeating units derived from propylene, but may also contain repeating units derived from the comonomer. Examples of suitable comonomers may include ethylene or other α-olefin comonomers as previously described. In many embodiments, the comonomer is ethylene. Impact copolymers are block copolymers comprising blocks of polypropylene homopolymers and blocks of propylene-ethylene copolymers.

[0038] The PP polymers used in this invention can be isotactic, syndiotactic, or atactic. In some embodiments, they are isotactic. In some embodiments, they are atactic. In some embodiments, they are syndiotactic.

[0039] PP polymers are typically characterized by their melt index. In some embodiments, the melt index (I2, measured at 230°C / 2.16 kg) of the PP polymer ranges from 0.2 g / 10 min to 50 g / 10 min. All individual values ​​and sub-ranges from 0.2 g / 10 min to 50 g / 10 min are included and disclosed herein. In some embodiments, the PP polymer for membrane applications may have a melt index of at least 0.3 g / 10 min, at least 0.05 g / 10 min, at least 1 g / 10 min, or at least 2 g / 10 min. In some embodiments, the PP polymer for membrane applications may have a melt index of at most 50 g / 10 min, at most 20 g / 10 min, at most 10 g / 10 min, at most 5 g / 10 min, or at most 4 g / 10 min.

[0040] Suitable PP polymers are known and can be marketed under trademarks such as Borstar, Innovene, and VERSIFY. ™ Commercially available. Other PP polymers can be prepared by solution, slurry, and / or gas-phase polymerization of propylene monomers and optionally comonomers in the presence of known processes, such as Ziegler-Natta catalysts, metallocene catalysts, or other single-point catalysts.

[0041] Some polyolefin elastomers contain copolymers or terpolymers of ethylene and / or propylene, and sometimes copolymers or terpolymers of ethylene and / or propylene with other comonomers. For example, some elastomers are terpolymers of ethylene, propylene, and dienes (such as butadiene). Examples of suitable polyolefin elastomers are given in ENGAGE. ™ INFUSE ™ AFFINITY™ VERSIFY ™ INTUNE ™ and NORDEL ™ Trademark for sale. Other polyolefin elastomers can be prepared by known polymerization procedures as already described. In some embodiments, the use of metallocene catalysts in the preparation of polyolefin elastomers may be useful.

[0042] In some embodiments, the polyolefin polymer may contain additives. Examples of common additives include antistatic agents, color enhancers, dyes, lubricants, fillers, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, nucleating agents, slip agents (such as erucamide), anti-blocking agents (such as talc), and combinations thereof. In some embodiments, additives (other than pigments and fillers) constitute no more than 5% by weight, or no more than 4% by weight, or no more than 3% by weight, or no more than 2% by weight, or no more than 1% by weight of the polyolefin. Pigments and fillers may sometimes constitute the majority of the polyolefin polymer, such as up to 10% by weight, 20% by weight, or 25% by weight. In some embodiments, additives constitute essentially 0% by weight of the polyolefin.

[0043] The amount of polyolefin polymer in the composition can depend on the intended use of the polymer blend. Polymer blends intended for direct use in the manufacture of articles such as films may contain high amounts of polyolefin and low amounts of other components. For example, in some embodiments, the polyolefin polymer comprises at least 90% by weight, at least 95% by weight, at least 97% by weight, at least 98% by weight, at least 99% by weight, at least 99.5% by weight, or at least 99.8% by weight of the composition of the present invention, based on the combined weight of the polyolefin, polyacid, and polyol. In some embodiments, the polyolefin polymer comprises no more than 99.99% by weight of the composition of the present invention, based on the combined weight of the polyolefin, polyacid, and polyol.

[0044] polyacid components

[0045] This invention uses a polyacid polymer, which is a polymer having an average of more than two carboxylic acid groups or metal carboxylate groups per molecule. In some embodiments, the polyacid polymer is a polyacrylic acid (PAA) polymer. PAA is a polymer or copolymer containing repeating units derived from acrylic acid or homologous materials (such as methacrylic acid or ethylacrylic acid), as shown in Formula 1:

[0046]

[0047] Each R 1 It is independently a hydrogen or alkyl group. In some embodiments, R 1It is hydrogen (derived from acrylic acid), and in some embodiments, R 1 It is a methyl group (derived from methacrylic acid).

[0048] In some embodiments, the polyacid polymer is an ionic polymer, in which some or all of the carboxylic acid groups have been converted into metal carboxylate groups. For example, in Formula 1, some or all of the acidic hydrogen atoms can be replaced by metal ions. Examples of common metal ions include alkali metal ions (such as sodium and potassium), alkaline earth metal ions (such as magnesium and calcium), and transition metal ions (such as zinc). In some embodiments, the polyacid polymer is not an ionic polymer, meaning that the proportion of carboxylic acid groups converted into metal carboxylate groups is substantially zero or low enough that it has no substantial effect on the properties of the polymer.

[0049] In some embodiments, at least 10%, at least 30%, at least 50%, at least 70%, or at least 80% of the acid groups in the polybasic acid polymer remain in an acidic state. In some embodiments, substantially all acid groups (up to 100%) in the polybasic acid polymer remain in an acidic state.

[0050] In some implementations, the polyacid polymer is a PAA homopolymer, wherein virtually all repeating units are derived from acrylic acid or homologs.

[0051] In some embodiments, the polyacid polymer is a PAA copolymer, wherein some repeating units are derived from acrylic acid or its homologs, and some repeating units are derived from comonomers. In some embodiments, at least 1% by weight, at least 3% by weight, at least 4% by weight, or at least 5% by weight of the repeating units in the PAA polymer are derived from acrylic acid or its homologs. In some embodiments, at most 40% by weight, at most 25% by weight, at most 20% by weight, at most 15% by weight, at most 12% by weight, or at most 10% by weight of the repeating units in the PAA polymer are derived from acrylic acid or its homologs. In some embodiments, at least 75% by weight, at least 80% by weight, at least 85% by weight, at least 88% by weight, or at least 90% by weight of the repeating units in the PAA polymer are derived from comonomers. In some embodiments, at most 99% by weight, at most 97% by weight, at most 96% by weight, or at most 95% by weight of the repeating units in the PAA polymer are derived from comonomers.

[0052] Suitable comonomers include unsaturated monomers capable of free radical polymerization. Examples of suitable comonomers include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethylene, propylene, and styrene. In some embodiments, the comonomer is ethylene.

[0053] Examples of commonly available PAA copolymers include copolymers containing 5 to 20 (or 5 to 15) wt% repeating units derived from acrylic acid or methacrylic acid and 80 to 95 (or 85 to 95) wt% repeating units derived from ethylene.

[0054] In some embodiments, the polyacid polymer is solid at ambient temperature. In some embodiments, the polyacid polymer has a melt temperature of at least 50°C, at least 60°C, at least 70°C, at least 80°C, at least 90°C, or at least 100°C. In some embodiments, the polyacid polymer has a melt temperature equal to or lower than that of conventional extrusion of polyolefins, which is the temperature at which the polyolefin becomes sufficiently plastic to be extruded but does not substantially degrade. In some embodiments, the polyacid polymer melts at a temperature of at most 190°C, at most 170°C, at most 150°C, or at most 130°C.

[0055] Suitable polyacid polymers can be such as NUCREL ™ Trademarked and commercially available. Other polyacid polymers can be prepared by free radical polymerization of acrylic acid or its homologues, optionally with comonomers, according to known procedures.

[0056] In the compositions of the present invention, the ratio of the polyacid polymer to the polyolefin is at least 100 ppmw. The optimal ratio depends on the intended use of the resulting polymer blend.

[0057] In some embodiments where the polymer blend is used directly to prepare molded articles (such as films), the ratio of the polyacid polymer to the polyolefin is at least 200 parts per million (ppmw), or at least 300 ppmw, or at least 400 ppmw, or at least 500 ppmw, or at least 600 ppmw, or at least 700 ppmw, or at least 800 ppmw, or at least 900 ppmw, or at least 1000 ppmw (0.1 wt%). In some embodiments where the polymer blend is used directly to prepare molded articles (such as films), the ratio of the polyacid polymer to the polyolefin is at most 10 wt%, or at most 5 wt%, or at most 3 wt%, or at most 2 wt%, or at most 1 wt%, or at most 0.5 wt%, or at most 0.3 wt%, or at most 0.2 wt%.

[0058] In some embodiments where the polymer blend is used as a masterbatch, the amount of the polyacid polymer can be high. For example, the ratio of the polyacid polymer to the polyolefin can be at least 1% by weight, at least 2% by weight, at least 3% by weight, or at least 5% by weight, and the ratio of the polyacid polymer to the polyolefin can be at most 25% by weight, at most 20% by weight, or at most 15% by weight.

[0059] polyol components

[0060] This invention uses polyols, which are compounds or polymers comprising an average of at least two reactive hydroxyl groups per molecule. In some cases, the polyol contains an average of more than two reactive hydroxyl groups per molecule, or an average of at least three reactive hydroxyl groups per molecule, or an average of at least four reactive hydroxyl groups per molecule, or an average of at least six reactive hydroxyl groups per molecule, or an average of at least eight reactive hydroxyl groups per molecule.

[0061] Examples of small molecule polyols include ethylene glycol, glycerol, and bisphenol A.

[0062] In some implementations, the polyol is a polyol polymer. Examples of polyol polymers include polyvinyl alcohol (PVOH). PVOH is a polymer or copolymer containing repeating units derived from vinyl alcohol, as shown in Formula 2. A common example of a PVOH polymer is an ethylene vinyl alcohol (EVOH) copolymer.

[0063]

[0064] In some embodiments, the PVOH polymer is a copolymer, wherein some repeating units are derived from vinyl alcohol and some repeating units are derived from comonomers. In some embodiments, at least 1% by weight, at least 5% by weight, at least 10% by weight, at least 15% by weight, at least 20% by weight, at least 25% by weight, or at least 30% by weight of the repeating units in the PVOH polymer are derived from vinyl alcohol. In some embodiments, at most 100% by weight, at most 75% by weight, at most 60% by weight, at most 50% by weight, at most 40% by weight, or at most 35% by weight of the repeating units in the PVOH polymer are derived from vinyl alcohol. In some embodiments, at least 25% by weight, at least 40% by weight, at least 50% by weight, at least 60% by weight, or at least 65% by weight of the repeating units in the PVOH polymer are derived from comonomers. In some embodiments, at most 99% by weight, at most 95% by weight, at most 90% by weight, at most 85% by weight, at most 80% by weight, at most 75% by weight, or at most 70% by weight of the repeating units in the PVOH polymer are derived from comonomers. In some implementations, the PVOH polymer is an ethylene vinyl alcohol (EVOH) copolymer.

[0065] Suitable comonomers include unsaturated monomers capable of free radical polymerization. Examples of suitable comonomers include vinyl acetate, ethylene, propylene, and styrene. In some embodiments, the comonomer is ethylene.

[0066] Examples of commonly available polyols include ethylene-vinyl alcohol copolymers containing 50 to 80 (or 55 to 75) mol% vinyl alcohol units and 20 to 50 (or 25 to 45) mol% repeating units derived from ethylene.

[0067] In some embodiments, the melt index of the polyol polymer is at least 0.1 g / 10 min, at least 0.5 g / 10 min, or at least 1 g / 10 min. In some embodiments, the melt index of the polyol polymer is at most 30 g / 10 min, at most 20 g / 10 min, or at most 10 g / 10 min.

[0068] In some embodiments, the polyol polymer is solid at ambient temperature. In some embodiments, the polyol polymer has a glass transition temperature of at least 40°C, at least 45°C, at least 50°C, or at least 55°C. In some embodiments, the polyol polymer has a glass transition temperature equal to or lower than the common extrusion temperature of the polyolefin, which is the temperature at which the polyolefin becomes sufficiently plastic to be extruded but does not substantially degrade. In some embodiments, the polyacid polyol melts at a temperature of at most 190°C, at most 170°C, at most 150°C, at most 130°C, or at most 100°C.

[0069] Suitable polyol polymers are commercially available, such as those under the trademarks Eval, Soarnol, Elvanol, and Vinarol. Other polyol polymers can be prepared by a two-step procedure: (1) polymerizing ethylene-vinyl acetate optionally with a comonomer to obtain a vinyl acetate polymer, and (2) hydrolyzing at least some of the acetate side groups on the vinyl acetate polymer to form hydroxyl side groups.

[0070] The ratio of the polyacid polymer to the polyol should be suitable for linking the polyacid polymer and the polyol via a condensation reaction between the acid groups on the polyacid polymer and the hydroxyl groups on the polyol. In some embodiments, the molar ratio of the acid groups on the polyacid polymer to the active hydroxyl groups on the polyol is at least 1:10, at least 1:5, at least 1:2, or at least 1:1.2. In some embodiments, the molar ratio of the acid groups on the polyacid polymer to the active hydroxyl groups on the polyol is at most 10:1, at most 5:1, at most 2:1, or at most 1.2:1. The polyacid is then an ionic polymer in which metal carboxylate groups may be included with the acid groups at this ratio.

[0071] In some embodiments where the polyol is a polymer, the weight ratio of the polyol polymer to the polyolefin is at least 20 ppmw. In some embodiments, the ratio of the polyol polymer to the polyolefin is at least 50 ppmw, at least 100 ppmw, at least 150 ppmw, at least 180 ppmw, or at least 200 ppmw. In some embodiments, the ratio of the polyol polymer to the polyolefin is at most 5% by weight, at most 3% by weight, at most 1% by weight, at most 0.5% by weight, at most 0.2% by weight, at most 1000 ppmw, at most 500 ppmw, or at most 300 ppmw.

[0072] In some embodiments where the polymer blend is used as a masterbatch, the amount of polyol polymer can be high. For example, the ratio of polyol polymer to polyolefin can be at least 0.2% by weight, at least 1% by weight, or at least 3% by weight, and the ratio of polyol polymer to polyolefin can be at most 15% by weight, at most 10% by weight, or at most 5% by weight.

[0073] Polymer blends, their preparation process and manufacturing

[0074] Polyolefins, polyacid polymers, and polyols are melt-blended in the previously described proportions under the following conditions: the polyacid polymer and the polyol polymer undergo a condensation reaction to form ester groups that crosslink the polyacid polymer and the polyol. Equipment for melt blending is commercially available, and the procedures for melt blending are well known. See, for example, Subramanian, Ch. 10 Processing Technology. In Polymer Blends and Composites: Chemistry and Technology In the literature, pp. 251-287, published by John Wiley & Sons in 2017. In summary, polyolefins, polyacid polymers, and polyols are subjected to heating and shearing in an extruder, blender, kneader, or similar equipment until they melt and become homogeneously blended together, and the acid / metal carboxyl groups on the polyacid polymer react with the hydroxyl groups on the polyol polymer to form ester bonds that crosslink the polymer. Extruders are commonly used blending equipment, and extrusion is a commonly used blending technique. See 02 Extrusion – Technical Guide, published by Qenos Pty, Ltd (2015) and available at qenos.com. In some embodiments, the melt temperature during blending is at least 180°C, at least 185°C, or at least 190°C. In some embodiments, the melt temperature during blending is at most 260°C, at most 250°C, at most 245°C, at most 230°C, at most 220°C, or at most 210°C.

[0075] Optionally, the melt-blended mixture may include other polymers. In some embodiments, the other polymers melt-blended with the combination of the present invention are compatible with polyolefin polymers. In some embodiments, the other polymers are melt-blended with the combination of the present invention in the presence of a compatibilizer that facilitates the compatibility of the other polymers with the polyolefin polymer. In some embodiments, the melt blend substantially excludes other polymers other than polyolefins, polyacids, and polyols.

[0076] Optionally, additives suitable for polyolefin polymers may be added during melt blending. Suitable additives and their uses have been previously described in this literature.

[0077] As previously described, during melt blending, acid (or metal carboxylate) groups on the polyacid polymer react with hydroxyl groups on the polyol to form ester bonds linking the polyacid polymer and the polyol in the condensation product. In some embodiments, multiple acid (or metal carboxylate) groups on the polyacid polymer react with multiple hydroxyl groups on the polyol to form a condensation product that forms a crosslinked network.

[0078] The reaction product is a polymer blend containing condensation products of polyolefin polymers, polyacid polymers, and polyols.

[0079] The polyolefin polymer in the polymer blend is the same as the polymer used in the melt blend, and has the same description, preferred embodiments, and concentration as previously described.

[0080] The condensation products in the polymer blend reflect the polyacid polymer and polyol used to prepare the blend. Based on the structures of the polyacid polymer and polyol, and based on the observed low level of phase separation, it is hypothesized that in some embodiments, the condensation products are cross-linked networks. It is further hypothesized that the condensation products form a semi-interpenetrating network, in which polyolefin molecules are physically entangled within the condensation product network.

[0081] The concentration of the condensation product reflects the combined concentration of the polyacid polymer and the polyol polymer during melt blending. The ratio of condensation product to polyolefin in the polymer blend is at least 100 ppmw. In some embodiments, the ratio of condensation product to polyolefin in the polymer blend is at least 200 ppmw, at least 300 ppmw, at least 400 ppmw, at least 500 ppmw, at least 600 ppmw, at least 700 ppmw, at least 800 ppmw, at least 900 ppmw, or at least 1000 ppmw. In some embodiments intended for use in the finished product, the ratio of condensation product to polyolefin in the polymer blend is at most 10 wt%, at most 5 wt%, at most 3 wt%, at most 2 wt%, at most 1 wt%, at most 0.5 wt%, at most 0.3 wt%, or at most 0.2 wt%.

[0082] In some embodiments where the masterbatch is intended for later blending with more polyolefins, the ratio of condensation product to polyolefin in the polymer blend is higher than that in the finished product. In some embodiments, the masterbatch contains at least 1% by weight, at least 3% by weight, or at least 5% by weight of condensation product. In some embodiments, the masterbatch contains at most 25% by weight, at most 20% by weight, or at most 15% by weight of condensation product.

[0083] In some embodiments, the blend is homogeneous – without substantial phase separation. In some embodiments, the blend is a semi-interpenetrating network (semi-IPN) containing a polyolefin polymer, which is largely uncrosslinked, and an interpenetrating crosslinked polymer network, which is a condensation product of a polyacid polymer and a polyol polymer.

[0084] The polymer blend exits the melt blending step as a melt, which can be used in conventional manufacturing processes to prepare films or other molded articles. Films can be prepared by known processes such as casting, blown film (optionally water-quenched), or extrusion coating.

[0085] • In cast film extrusion, the die is a slit die, and the film is extruded onto a cooling roller, quenched, and wound onto the roller.

[0086] • In blown film extrusion, the die is a circular die. Air bubbles (such as air or nitrogen) are trapped within the circular film between the die and a pair of downstream pressure rollers. The film passes through the air bubbles and is biaxially stretched before it cures. The film is then cooled, flattened, and wound onto the rollers.

[0087] • In extrusion coating, molten resin is extruded as a coating onto a substrate such as paper, corrugated or non-corrugated cardboard, fiberboard, metal foil, cellulose, nonwoven mat, or plastic film.

[0088] In some embodiments, the polymer melt is extruded alone to form a monolayer film. In some embodiments, the polymer melt is co-extruded with one or more other polymers to form one or more layers in a multilayer structure. For example, it is known to co-extrude polyolefins into a multilayer structure, wherein the polyolefin layer is the structural layer that provides the primary physical properties of strength and flexibility to the multilayer film, and the other layers may include one or more of the following:

[0089] • Quickly forms a robust heat-sealing layer for heat-sealed components, such as those that can be ELITE ™ Trademarked reinforced polyethylene polymers and can be DOWLEX ™ Certain LLDPE polymers obtained through trademark purchase.

[0090] • A printing layer containing polymers selected to provide a good appearance (such as high gloss) and a good surface for ink adhesion. Examples of common polymers in printing layers include LLDPEs derived from Ziegler-Natta or metallocene catalysts. Common printing layer polymers may be branded as DOWLEX. ™ GM 8051, DOWLEX ™ TG2085B, DOWLEX ™ GM8070, DOWLEX ™ 2049, ELITE ™ AT 6501 and INNATE ™ ST50 was purchased commercially.

[0091] • Barrier layers used to reduce the migration of gases, moisture, and / or flavor elements through multilayer membranes. Examples of common barrier polymers include ethylene vinyl alcohol, ethylene vinyl acetate, polyvinylidene chloride, polypropylene, polyamide, polyethylene terephthalate, and polyvinyl chloride. Polymers used in barrier layers may be such as those under the trademark SARAN. ™ Eval, Nylon-6, and Miramid are available through commercial purchase.

[0092] • An adhesive layer used to improve the adhesion of different layers in a multilayer film, especially when the different layers contain incompatible polymers. Examples of common adhesive layer polymers include ethylene-acrylic acid copolymers and ethylene-vinyl acetate copolymers. Examples of common adhesive layers can be found under the trademark BYNEL. ™ Plexar, EMAC, Surpass, and Novapol are commercially available. They contain a printing layer of polymer that forms a good surface for printing.

[0093] Multilayer films can have 2 to 9 or more layers.

[0094] In some embodiments, the membrane has a thickness of at least 10 μm, at least 20 μm, or at least 30 μm. In some embodiments, the membrane has a thickness of at most 200 μm, at most 150 μm, at most 120 μm, or at most 100 μm.

[0095] Alternatively, polymer melts can be molded into molded articles using known processes such as extrusion, injection molding, compression molding, and blow molding. Each of these processes is well-known and described in numerous publications, and the equipment for implementing them is commercially available.

[0096] In a common alternative, the polymer melt is extruded as a strip, cooled, and shredded to form granules. See, for example, "Melt-to-Pellet Conversion" published by KraussMaffei at https: / / www.kraussmaffei.com / en / download-area. The masterbatch and finished polyolefin resin described above are typically granulated for ease of storage and transport. Some granules may have a diameter between 1 mm and 5 mm and a length between 1 mm and 10 mm. The granules are then remelted using the procedures described above and molded into articles.

[0097] Compared to the base polyolefin polymers used to prepare the polymer blends of the present invention, the polymer blends of the present invention can have improved physical properties. For example,

[0098] • In some embodiments, when measured according to the test method, the puncture force of a monolayer film containing the polymer blend of the present invention is at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30% higher than that of a similar film containing the corresponding polyolefin polymer. There is no maximum expected improvement, but an improvement greater than 100% or 50% may be unnecessary.

[0099] • In some embodiments, when measured according to the test method, the pre-puncture elongation of a monolayer film containing the polymer blend of the present invention is at least 2%, or at least 5%, or at least 10%, or at least 15%, or at least 20% higher than that of a similar film containing the corresponding polyolefin polymer. There is no maximum expected improvement, but improvements greater than 100% or 50% may be unnecessary.

[0100] • In some embodiments, when measured according to the test method, the dart impact resistance of the polymer blends of the present invention is at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25% higher than that of the corresponding polyolefin polymer. There is no maximum expected improvement, but an improvement greater than 100% or 50% may be unnecessary.

[0101] Test methods

[0102] The parameters described in this application can be measured using the following measurement methods:

[0103]

[0104] Example

[0105] The raw materials shown in Table 1 are used in the examples:

[0106]

[0107] Small-scale (10 kg / hr) extrusion (Examples IE A-IE C of this invention and Comparative Examples CE 1-CE 5)

[0108] Polyolefins, polyacids, and polyols were manually mixed in the proportions shown in Table 6. The mixture was co-extruded in a Dr. Collins laboratory-scale extruder equipped with a blown film production line. The screw diameter was 30 mm, and the screw length was 25 times the diameter. The annular die size was 60 mm. The unit operated at 50 rpm under a melt pressure of 261 bar and a melt temperature of 248 °C. The temperature profiles are shown in Table 2. The die clearance was 0.8 mm to 1.2 mm. The blow-up ratio was 2.5, and the rolling speed was 3.6 m / min to 3.8 m / min.

[0109]

[0110] The extruded product is a monolayer film with a thickness of approximately 50 micrometers. The puncture force, puncture elongation, and dart impact strength of the film were tested as described in the test method. The results are shown in Table 6.

[0111] Granulation and medium-scale (22 kg / hr) extrusion (Examples IED and IEE of the present invention and Comparative Example CE 6)

[0112] Polyolefins, polyacids, and polyols were premixed in the proportions shown in Table 6 and granulated using a twin-screw extruder with a rotary blade cutting system. Each screw had a diameter of 24 mm. Temperature profiles are shown in Table 3. The granules were cooled in a 15°C water bath before cutting.

[0113]

[0114] The resulting pellets were extruded on a 45mm Covex blown film extrusion line at a rate of approximately 22.5 kg / hr. The settings are shown in Table 4.

[0115]

[0116] The extruded product is a monolayer film with a thickness of approximately 50 micrometers. The puncture force, puncture elongation, and dart impact strength of the film were tested as described in the test method. The results are shown in Table 6.

[0117] Large-scale (200 kg / hr) extrusion (Examples IE F-IE H of the present invention and Comparative Example CE 7)

[0118] The polyolefin, polyacid, and polyol were manually mixed in the proportions shown in Table 6. The mixture was then extruded into a 5-layer structure (all layers being resins of the present invention) using a Macchi Coex 5Flex blown film extruder. Extrusion details are shown in Table 5.

[0119]

[0120] The extruded product is a five-layer film with a thickness of approximately 50 micrometers, each layer having the same composition. The puncture force, puncture elongation, and dart impact strength of the film were tested as described in the test method. The results are shown in Table 6.

[0121] Examples show that polyolefins extruded with polyacids and polyols have improved puncture resistance compared to polyolefins extruded with polyacids or polyols alone or without polyacids or polyols.

[0122]

Claims

1. A polyolefin composition comprising: a) at least 50% by weight of a polyolefin polymer; and b) at least 100 ppmw of a polyacid polymer; and c) at least 20 ppmw of a polyol, wherein the weight ratio is based on the combined weight of the polyolefin polymer, the polyacid polymer, and the polyol.

2. The polyolefin composition according to claim 1, wherein the polyolefin polymer comprises polyethylene.

3. The polyolefin composition according to any of the preceding claims, wherein the polyolefin polymer comprises linear low-density polyethylene.

4. The polyolefin composition according to any of the preceding claims, wherein the polyacid polymer comprises a copolymer containing repeating units derived from acrylic acid or methacrylic acid and repeating units derived from one or more comonomers selected from the group consisting of ethylene, propylene and styrene.

5. The polyolefin composition according to any of the preceding claims, wherein the polyacid polymer is an ionomer.

6. The polyolefin composition according to any of the preceding claims, wherein the polyacid polymer is not an ionic polymer.

7. The polyolefin composition according to any of the preceding claims, wherein the polyol comprises a copolymer containing repeating units of vinyl alcohol and repeating units derived from ethylene, propylene or styrene.

8. The polyolefin composition according to any of the preceding claims, wherein the molar ratio of the acid group in the polyacid polymer to the hydroxyl group in the polyol is 5:1 to 1:

5.

9. The polyolefin composition according to any of the preceding claims, wherein a) the polyolefin polymer is a polyethylene polymer and comprises at least 75% by weight of the polyolefin composition; b) the polyacid polymer comprises a copolymer containing repeating units derived from acrylic acid or methacrylic acid and repeating units derived from ethylene; and c) the polyol comprises a copolymer containing repeating units of vinyl alcohol and repeating units derived from ethylene, wherein the molar ratio of the acid group in the polyacid polymer to the hydroxyl group in the polyol is 5:1 to 1:5, and wherein the weight ratio is based on the combined weight of the polyolefin polymer, the polyacid polymer, and the polyol.

10. The polyolefin composition of claim 9, wherein the polyolefin composition comprises: a) at least 98% by weight of the polyolefin polymer; b) 100 ppmw to 2000 ppmw of the polyacid polymer; and c) 50 ppmw to 1000 ppmw of the polyol, wherein the weight percentages are based on the combined weight of the polyolefin polymer, the polyacid polymer, and the polyol.

11. The polyolefin composition of claim 9, wherein the polyolefin composition comprises: a) 75% to 98% by weight of the polyolefin polymer; b) 2% to 20% by weight of the polyacid polymer; and c) 1% to 10% by weight of the polyol; wherein the weight percentages are based on the combined weight of the polyolefin polymer, the polyacid polymer, and the polyol.

12. A method for preparing a polymer blend, the method comprising the step of melt blending a polyolefin composition according to any one of claims 1 to 11 under the following conditions: causing the polyacid polymer and the polyol to undergo a condensation reaction to form ester groups that crosslink the polyacid polymer and the polyol.

13. The method of claim 12, wherein the melt blending is carried out in an extruder.

14. A polymer blend prepared by the method according to claim 12, the polymer blend comprising a polyolefin polymer and a condensation product formed by the condensation of a polyacid polymer and a polyol, the condensation product being dispersed within the polyolefin polymer.

15. A polymer blend comprising: a) at least 50% by weight of a polyolefin polymer; b) at least 150 ppm of a condensation product formed by the condensation of a polyacid polymer and a polyol, the condensation product being dispersed within the polyolefin polymer, wherein the weight ratio is based on the combined weight of the polyolefin polymer and the condensation product.

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