HIGH CONCENTRATION POLYMER MASTERBATCHES OF LIQUID PHOSPHITE ANTIOXIDANTS WITH IMPROVED RESISTANCE TO HYDROLYSIS

Abstract

Provided herein are compositions of polyolefin masterbatches containing liquid phosphite antioxidants intended for use as antioxidizing preparations for polyolefins. The polyolefin masterbatches herein exhibit good shelf stability including reduced blooming of the liquid phosphite and reduced consumption of the active phosphite during storage due to hydrolysis or other undesirable reactions.

Claims

1. A polyolefin masterbatch composition comprising: a. a liquid phosphite antioxidant present in an amount of greater than about 4% by weight based on the total weight of the composition; b. an inorganic solid coadditive capable of acting as an acid neutraliser present in an amount of 5 to 100% by weight based on the total weight of liquid phosphite antioxidant in the composition; and c. an immiscible polymer blend which comprises: (i) a first carrier comprising a polyethylene or polyethylene copolymer with a density greater than about 0.910 g/cm.sup.3 or an isotactic homopolymer polypropylene or polypropylene impact copolymer with a density greater than about 0.898 g/cm.sup.3 or a blend or combination thereof; and (ii) a second carrier comprising a polyolefin or polyolefin copolymer with a density less than about 0.895 g/cm.sup.3 or an ethylene-vinyl acetate copolymer or an acid copolymer or a blend or combination thereof.

2. A polyolefin masterbatch composition as claimed in claim 1 wherein the polyethylene or polyethylene copolymer of the first carrier has a density greater than about 0.914 g/cm.sup.3.

3. A polyolefin masterbatch composition as claimed in claim 1 wherein the polyolefin or polyolefin copolymer of the second carrier has a density less than about 0.890 g/cm.sup.3.

4. A polyolefin masterbatch composition as claimed in claim 1 wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content of greater than 10% by weight.

5. A polyolefin masterbatch composition as claimed in claim 1 wherein the first carrier is characterized by a solubility of a liquid phosphite in the carrier of less than 9% at 45 C.

6. A polyolefin masterbatch composition as claimed in claim 1 wherein the second carrier is characterized by a solubility of a liquid phosphite in the carrier of greater than 11% at 45 C.

7. A polyolefin masterbatch composition as claimed in claim 1 wherein the liquid phosphite antioxidant is present in an amount of greater than about 4.5 wt % based on the total weight of the composition.

8. A polyolefin masterbatch composition as claimed in claim 1 wherein the liquid phosphite antioxidant is selected from the group comprising: triaryl phosphites, trialkyl phosphites, alkylphenol-free polymeric polyphosphites, and combinations thereof.

9. A polyolefin masterbatch composition as claimed in claim 1 wherein the liquid phosphite antioxidant is liquid at a temperature of less than about 60 C.

10. A polyolefin masterbatch composition as claimed in claim 1 wherein the inorganic solid coadditive is present in the range 7 to 80% by weight based on the weight of the phosphite antioxidant in the composition.

11. A polyolefin masterbatch composition as claimed in claim 1 wherein the inorganic solid coadditive is selected from the group comprising: zinc oxide, calcium oxide, synthetic hydrotalcites, hydrotalcite-like synthetic materials, dehydrated synthetic hydrotalcites, and combinations thereof.

12. A polyolefin masterbatch composition as claimed in claim 1 wherein the composition further comprises an organic acid neutraliser.

13. A polyolefin masterbatch composition as claimed in claim 1 wherein the first carrier is selected from the group comprising high-density polyethylene, linear low-density polyethylene, copolymers thereof, and combinations thereof.

14. A polyolefin masterbatch composition as claimed in claim 1 wherein the first carrier is a polyethylene, a branched low density polyethylene (LDPE), a substantially linear polyolefin or alpha-olefin copolymer, a substantially linear polyethylene or polyethylene copolymer, a linear low density polyethylene (LLDPE), a high-density polyethylene (HDPE), or a polypropylene homopolymer.

15. A polyolefin masterbatch composition as claimed in claim 1 wherein the first carrier does not comprise linear plastomers or elastomers having a density of less than about 0.895 g/cm.sup.3.

16. A polyolefin masterbatch composition as claimed in claim 1 wherein the second carrier has a solubility of the liquid phosphite antioxidant in said second carrier of greater than about 12% at 45 C.

17. A polyolefin masterbatch composition as claimed in claim 1 wherein the second carrier is selected from the group comprising ethylene-alpha olefin copolymers, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, acid copolymers and combinations thereof.

18. A polyolefin masterbatch composition as claimed in claim 1 wherein the first and second carriers are present in a ratio of between about 20:1 and about 2:3.

19. A polyolefin masterbatch composition as claimed in claim 1 further comprising additional polymer additives and carrier polymers.

20. A polyolefin masterbatch composition as claimed in claim 1 wherein the second carrier exists as a dispersed phase in the first polymer carrier matrix or wherein the first and second carriers are present as cocontinuous phases.

21. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG. 1 depicts a scanning electron microscope (SEM) image demonstrating the morphology of Example E10. Item 1 is an elongated dispersed phase of Vistamaxx 6502, the second carrier. The Vistamaxx is identifiable as the phase with the smoother topography in this cryo-microtomed sample. Item 2 is the continuous Surpass CCs-757-A High Density Polyethylene (HDPE) matrix, which is the first carrier. The Surpass is identifiable by the rougher topography. Item 3 shows mineral-like particles which are the DHT-4C acid neutralizing coadditive.

[0056] FIG. 2 depicts an SEM image of Example E35 demonstrating the morphology of the example, which appears to be co-continuous. Item 1 is the Vistamaxx 6502, the second carrier. The Vistamaxx is identifiable as the phase with the smoother topography in this cryo-microtomed sample. Item 2 is the Surpass CCs-757-A High Density Polyethylene (HDPE), the first carrier. Item 3 shows mineral-like particles, which are the DHT-4C acid neutralizing coadditive. Item 4 shows debonding of the first and second carrier believed to be caused by the microtoming process.

[0057] FIG. 3 depicts an SEM image of Example E36 demonstrating the morphology of the example, which appears to be co-continuous. Item 1 is the Vistamaxx 6502, the second carrier. The Vistamaxx is identifiable as the phase with the smoother topography in this cryo-microtomed sample. Item 2 is the Surpass CCs-757-A High Density Polyethylene (HDPE), the first carrier. Item 3 shows mineral-like particles, which are the DHT-4C acid neutralizing coadditive. Item 4 shows debonding of the first and second carrier believed to be caused by the microtoming process.

[0058] FIG. 4 depicts an SEM image of Example E37 demonstrating the morphology of the example. It appears that Vistamaxx is the continuous phase. Item 1 is the Vistamaxx 6502, the second carrier. The Vistamaxx is identifiable as the phase with the smoother topography in this cryo-microtomed sample. Item 2 is the Surpass CCs-757-A High Density Polyethylene (HDPE), the first carrier. Item 3 showing mineral-like particles are the DHT-4C acid neutralizing coadditive. Item 4 shows debonding of the first and second carrier believed to be caused by the microtoming process.

DETAILED DESCRIPTION OF THE INVENTION

[0059] The particulars of the invention shown herein are by way of example. They are meant to illustrate various embodiments of the invention and are not meant to limit the scope of the invention.

[0060] Given below are the condensed (by no means exhaustive) customary definitions known in the art of certain terms which may aid in the description of the invention. The Compendium of Polymer Terminology and Nomenclature, IUPAC Recommendations, 2008 by RSC Publishing (hereafter referred to as the IUPAC Compendium) is herein incorporated by reference. The IUPAC definition should be considered, unless another definition is offered herein, in which case the definition offered herein shall be considered.

[0061] Base Polymer is the polymer which is to be colored, functionalized, stabilized or otherwise modified by additives or masterbatch.

[0062] Blooming is defined with reference to the IUPAC Compendium as a process in which one component of a polymer blend, usually not a polymer, undergoes phase separation and migration to an external surface of the polymer blend. In the context of the current invention this includes the migration of a liquid phosphite to the external surface of a masterbatch of liquid phosphite.

[0063] Carrier Polymer is the polymer or polymer blend that, when combined with fillers, colorants or additives, will encapsulate them to form a masterbatch. The carrier polymer should preferably be compatible with the base polymer that is being modified by the masterbatch.

[0064] Co-continuous phase domains, or co-continuous phases are the phases, in an immiscible polymer blend, in which a continuous path through either phase domain may be drawn to all phase domain boundaries without crossing any phase domain boundary.

[0065] Co-continuous morphology, is a morphology of an immiscible polymer blend, comprised of co-continuous phase domains.

[0066] Continuous Phase Domain, also referred to as the continuous phase, is the phase domain, in an immiscible polymer blend with a disperse morphology, through which a continuous path to all phase domain boundaries may be drawn without crossing a phase domain boundary.

[0067] Compatible Polymer Blend, is defined in the IUPAC Compendium as an immiscible polymer blend exhibiting macroscopically uniform physical properties.

[0068] Copolymer, is defined in the IUPAC Compendium as a polymer derived from more than one species of monomer. Note: Copolymers that are obtained by copolymerization of two monomer species are sometimes termed bipolymers, those obtained from three monomers terpolymers, those obtained from four monomers quaterpolymers, etc.

[0069] Disperse Morphology, is a morphology of an immiscible polymer blend comprised of a dispersed phase domain and continuous phase domain.

[0070] Dispersed Phase Domain, or simply dispersed phase is the phase domain, in an immiscible polymer blend which forms a disperse morphology, that is surrounded by a continuous phase but isolated from all other similar phase domains within the mixture.

[0071] Immiscible polymer blend, also referred to as a heterogeneous polymer blend, is defined in the IUPAC Compendium and further clarified here. An immiscible polymer blend is a polymer blend which forms more than a single phase. It should be noted that immiscibility of a given blend of polymers may be limited to a certain range of temperature, pressure and ratio of the constituent polymers. It should also be noted that miscibility should not be confused with compatibility and that an immiscible polymer blend may be a compatible polymer blend or an incompatible polymer blend. It should also be noted that an immiscible polymer blend may form a disperse phase morphology, or a co-continuous phase morphology depending on various factors including the ratio of components, their viscosities, interfacial tensions, and mixing conditions, as is known in the art.

[0072] Masterbatch is a concentrated mixture of pigments and/or additives which are encapsulated or dissolved during a heating and mixing process into a carrier polymer which is then cooled and cut into a granular shape. A masterbatch can be added to a base polymer in order to deliver the desired concentration of pigments or additives to the base polymer.

[0073] Melt Flow Rate (MFR) is as defined in ASTM D1238-20. Units of measure are in grams per 10 minutes.

[0074] Plate out is the migration of additives out of the polymer and their deposition on to polymer processing equipment during processing.

[0075] All percentages described in this document shall refer to the percentage on a weight basis.

[0076] It has surprisingly been found that the masterbatch compositions of the invention provide for a high-concentration liquid phosphite masterbatch with improved shelf-life. Improved shelf life, in the scope of this invention, means that the masterbatch exhibits reduced blooming of the additive to the surface of the masterbatch and reduced hydrolysis of the liquid phosphite component during storage of the masterbatch.

[0077] Liquid phosphite antioxidants of the present invention are liquids at temperatures of less than 60 C. Preferred liquid phosphite antioxidants of the present invention are liquids at temperatures of less than 50 C. Most preferred liquid phosphite antioxidants of the present invention are liquids at ambient conditions of 23 C. Liquid phosphite antioxidants of the present invention are used for providing stabilization to polyolefins, as is known in the art. Examples of liquid phosphite antioxidants (liquid phosphites) of the present invention include triaryl phosphites, trialkyl phosphites, mixtures of triaryl and trialkyl phosphites, and alkylphenol-free liquid polymeric polyphosphites.

[0078] More particularly, liquid phosphites of the present invention include the reaction mass of bis[2,4-bis(2-methylbutan-2-yl)phenyl] 4-(2-methylbutan-2-yl)phenyl phosphite and 2,4-bis(2-methylbutan-2-yl)phenyl bis[4-(2-methylbutan-2-yl)phenyl] phosphite and tris[4-(2-methylbutan-2-yl)phenyl] phosphite, which is sold under CAS number 939402-02-5; this mixture is alternately referred to as phosphorous acid, mixed 2,4-bis(1,1-dimethylpropyl)phenyl and 4-(1,1-dimethylpropyl)phenyl triesters. Also suitable is tris(p-tert-pentylphenyl) phosphite (CAS #864-56-2).

[0079] Liquid phosphites suitable for practising the present invention also include tri(alkylaryl) liquid phosphite antioxidants as claimed in U.S. Pat. No. 7,888,414, liquid phosphites produced under the tradename Weston 705T by SI Group, alkylphenol-free liquid polymeric polyphosphites as claimed in U.S. Pat. Nos. 8,563,637, and 8,981,042 and liquid polymeric polyphosphites produced under the tradenames Doverphos LGP11 and Doverphos LGP12 by Dover Chemical.

[0080] It should be noted that it is a common practice to add a small amount of an acid neutralizer such as triisopropanolamine (TIPA) as a minor component to liquid phosphites. TIPA is an organic acid-neutralizer and not the inorganic solid coadditive of the present invention. TIPA may or may not be present as an optional additive of the present invention.

[0081] Inorganic solid coadditives of the present invention are inorganic solids capable of performing as acid neutralizers. Acid neutralizing coadditives of the present invention include metal oxides of calcium and zinc as well as hydrotalcite and hydrotalcite-like minerals. Such acid neutralizing coadditives are known in the art as additives in polyolefins. Acid-neutralizing coadditives of the present invention are preferably of a particle size suitable for dispersion into polyolefins. They may optionally be surface treated in order to aid dispersion into a polymer.

[0082] Specific examples of inorganic, acid neutralizing coadditives of the present invention include hydrous hydrotalcite, anhydrous hydrotalcite and hydrotalcite-like minerals. Specific examples of hydrous hydrotalcite and hydrotalcite like minerals include Kisuma DHT-4A, Kisuma DHT-4V, Kisuma ZHT-4V, Kisuma DHT-4A-2, Clariant Hycite 713, Doobon CLC-120, and GCH Sipax AC-207.

[0083] Calcined anhydrous hydrotalcites are also suitable. Specific examples of calcined anhydrous hydrotalcite include Kisuma DHT-4C. Also suitable is zinc oxide, specific examples of which include American Zinc Recycling Kadox 911, US Zinc AZO 77HSA and Zochem Zoco 102USP. Calcium oxide is also suitable, specific examples of which include Omya Caloxol CP2F.

[0084] Blends or combinations of any of the above examples are also suitable for use as the inorganic solid coadditive of the present invention.

[0085] Most preferably, the acid neutralizing coadditives of the present invention can also absorb water. Without wishing to be constrained by theory, the incorporation of such additives, may allow the trapping of any small amounts of water present or migrating into the masterbatch. Trapping of the water may make it unavailable to hydrolyze the liquid phosphite.

[0086] The immiscible polymer blend of the invention comprises a first carrier comprising a polyethylene or polyethylene copolymer with a density greater than about 0.910 g/cm.sup.3 or an isotactic homopolymer polypropylene or polypropylene impact copolymer with a density greater than about 0.898 g/cm.sup.3 or a blend or combination thereof; and a second carrier comprising a polyolefin or polyolefin copolymer with a density less than about 0.895 g/cm.sup.3 or an ethylene-vinyl acetate copolymer or an acid copolymer or a blend or combination thereof. Immiscible Polymer Blends that serve as the carrier polymer of the masterbatch of the present invention are immiscible in the solid state. The polymers of the blend are immiscible and form either a disperse morphology or a co-continuous morphology in the solid state. The formation of a dispersed morphology wherein the second carrier is dispersed in the first carrier matrix is preferable. However, the formation of a co-continuous structure between the two immiscible polymers is also possible. The formation of a dispersed morphology wherein the first carrier is dispersed in the second carrier matrix is also possible, where the concentration of the first carrier is still relatively high, but this is not the most preferred morphology of the present invention. No determination has been made as to whether or not the polymers of the blend composition are miscible or immiscible during processing at higher temperatures in the molten state during the process of preparing the masterbatch by compounding. It is understood that miscibility of polymers is dependent on factors including the nature of the polymers, their relative concentrations as well as temperature and pressure of the system.

[0087] The polymers of the immiscible polymer blend are chosen as follows. The First Carrier of the Immiscible Polymer Blend is comprised of a single polyolefin or blend of polyolefins. This First Carrier is characterized by a solubility of the liquid phosphite in the First Carrier of less than 9%, preferably less than 8%, and most preferably less than 6% at 45 C. Examples of polymers suitable as the First Carrier will preferably form the continuous phase in a disperse morphology or a co-continuous phase in a co-continuous phase of the Immiscible Polymer Blend of the current invention.

[0088] Examples of the First Carrier of the Immiscible Polymer Blend of the current invention include branched low density polyethylene (LDPE) with a density of 0.91 to 0.94 g/cm.sup.3. Examples of such LDPEs include LyondellBasell Petrothene NA219000.

[0089] Substantially linear polyolefins and linear alpha-olefin copolymers are also suitable for practising the invention. These include substantially linear polyethylene and polyethylene copolymers covering the range of densities from 0.91 to 0.965 g/cm.sup.3 inclusive.

[0090] Such linear polyethylenes and polyethylene copolymers include linear low density polyethylenes (LLDPE) including butene, hexene, octene or other low alpha-olefin copolymers of polyethyelene with a density in the range of 0.91 to 0.925 g/cm.sup.3. Examples of such LLDPEs include LyondellBasell Petrothene GA502024.

[0091] Medium density polyethylenes (MDPE) including butene, hexane, octene or other low alpha-olefin copolymers of polyethyelene with a density in the range of 0.926 to 0.940 g/cm.sup.3 are also suitable for practising the invention. Examples of such an MDPE includes ExxonMobil Chemical LL8555.25.

[0092] Also suitable are high density polyethylene (HDPE) including HDPE homopolymers, as well as, butene, hexene, octene or other short-chain alpha-olefin copolymers of polyethylene with a density equal to or greater than 0.941 g/cm.sup.3. Examples of such a HDPE resin includes ExxonMobil Chemical HDPE HD6706.17 and Nova Chemicals Surpass CCs757-A. Preferably the substantially linear polyethylene is characterized by a low water vapour transmission rate (WVTR) relative to the second carrier.

[0093] Also suitable are semi-crystalline polypropylenes including isotactic homopolymer polypropylene with a density greater than 0.898 g/cm.sup.3 and heterogeneous ethylene-propylene copolymers, also known as impact copolymers with a density greater than 0.898 g/cm.sup.3. Homopolymer polypropylenes are preferred. Preferably the homopolymer polypropylene will have a density of 0.90 g/cm.sup.3 or greater. Examples of such homopolymer polypropylenes include LyondellBasell's Pro-fax 6301, Braskem's FF030F2, and ExxonMobil Chemical's PP1105E1. An example of an impact copolymer useful in the present invention includes LyondellBasell's Purell EP274P.

[0094] The Second Carrier of the immiscible polymer blend of the present invention comprises polyolefins, polyolefin copolymers, or ethylene-vinyl acetate copolymers (EVAc) or blends thereof, which, when mixed into the First Carrier in sufficient concentration, form a second immiscible phase. The second carrier preferably forms an immiscible dispersed phase in a disperse morphology or an immiscible co-continuous phase in a co-continuous morphology of the Immiscible Polymer Blend. The Second Carrier is further characterized as having a solubility of the liquid phosphite of greater than 11%, preferably more than 12% and most preferably higher than 13% at a temperature of 45 C. Second carriers of the present invention are typically characterised by a high amorphous content and low crystallinity compared to the first carrier.

[0095] Examples of suitable polymers for the Second Carrier of the polymer carrier blend include ethylene-propylene copolymers. Preferred ethylene-propylene copolymers of the present invention have a density of less than 0.895 g/cm.sup.3 and a Melt Flow Rate (MFR) (ASTM D1238-13 at 190 C. and 2.16 kg) of between 0.2 and 100.0 g/10 min. More preferred ethylene-propylene copolymers of the present invention have a density of less than 0.88 g/cm.sup.3 and a MFR (190 C., 2.16 kg) of between 0.5 and 50 g/10 min. Examples of suitable ethylene-propylene copolymers include Vistamaxx 3000, 3020FL, 6102, 6202 and 6502.

[0096] Ethylene-vinyl acetate copolymers (EVAc) are also suitable polymers for the second carrier. Preferred EVAC polymers have an MFR of 0.2 to 50 g/10 min. Examples of EVAC polymers of the present invention include ExxonMobil Escorene LD768.MJ.

[0097] Also suitable as the second carrier of the invention are ethylene-alpha olefin copolymers. Ethylene-alpha olefin copolymers of the present invention have a density of less than 0.905 g/cm.sup.3 and more preferred ethylene-alpha olefin copolymers have a density of less than 0.895 g/cm.sup.3 and a MFR of 0.2 to 50 g/10 minutes. Examples of ethylene-alpha olefins suitable for the present invention include ExxonMobil's plastomers such as Exact 8201 and Exact 4059 and Dow's Engage polyolefin elastomers such as Engage XLT8677.

[0098] Acid copolymers such as ethylene acrylic acid copolymers and ethylene methyl acrylate copolymers are also suitable for practising the invention.

[0099] The range of polymers that comprise the First Carrier and Second Carrier, as above, must be chosen with reference to one another and with a range of concentrations to, in fact, form an immiscible polymer blend. The First Carrier is preferably present at a ratio of 20:1 to 2:3 with reference to the Second Carrier. More preferably the First Carrier is present at a ratio of 15:1 to 3:2 with reference to the Second Carrier. In the case of any doubt, the formation of an immiscible polymer blend can be demonstrated by means known to one skilled in the art by various techniques including microscopy.

[0100] Preferably, the immiscible polymer blend is a compatible polymer blend, where the First Carrier and Second Carrier are characterized by good compatibility.

[0101] It is preferable for the carrier polymers of the masterbatch of the present invention to be compatible with the base polymer it is to be let down into. It is most preferable for the First Carrier of the masterbatch to be closely matched with or even identical to the base polymer it is to be let down into. By way of an example, if the masterbatch of the present invention was to be used to provide antioxidizing stabilization to a film grade LLDPE of, for example, 0.918 g/cm.sup.3 density and an MFR of 1.0 g/10 min, it would be preferable for the Immiscible Polymer Blend, which acts as the carrier of the masterbatch, to comprise a First Carrier of an LLDPE of similar density and MFR.

[0102] It is also preferable for the Second Carrier polymer of the masterbatch of the present invention to be compatible with the base resin that it will be letdown into. Even more preferably the Second Carrier, although immiscible with the First Carrier of the masterbatch of the present invention at the concentration used in the masterbatch, is completely miscible at the lower concentration of use in the Base Polymer, such that it does not exist as a separate phase in the base polymer. This is, however, not necessary for the successful application of the present invention. If the Second Carrier, upon addition to the base polymer, exists as a separate dispersed phase, it is preferable that the dispersed phase size should be small enough that it will not cause a readily visible defect. This can be facilitated by ensuring that the domain size of the Second Carrier in the liquid phosphite masterbatch is well dispersed before it is let down into the base polymer. Preferably the Second Carrier exists as a dispersed phase with a diameter of less than 100 microns in the masterbatch in order to facilitate good dispersion into the base polymer. More preferably the Second Carrier has a dispersed phase diameter of less than 10 microns in the masterbatch. Most preferably the Second Carrier has a dispersed phase diameter of less than 5 microns.

[0103] Without wishing to be constrained by theory, it is believed that use of the immiscible polymer blend of two polymers as the carrier for the liquid phosphite antioxidant in the masterbatch of the present invention provides for both high uptake of the liquid phosphite in the Second Carrier, and reduced migration and blooming of the liquid phosphite to the surface of the pellet through the First Carrier, which is characterized by lower solubility of the liquid phosphite and higher crystallinity than the Second Carrier. For this reason, it is believed that a disperse phase morphology where the Second Carrier is completely encapsulated by the First Carrier, is preferable. However, it has been found that a co-continuous morphology of the First and Second carriers works very well. In addition, it is believed that a First Carrier with a low WVTR (lower than the disperse phase) acts as a barrier between the environment and the liquid phosphite concentrated in the dispersed phase, and thereby limits or substantially decreases the ingress of water and thus the rate of hydrolysis of the liquid phosphite. The addition of the acid-neutralizing coadditive is believed to neutralize any initial acidic hydrolysis products of the liquid phosphite and thereby reduce or delay further hydrolysis of the liquid phosphite antioxidant. The preferred use of a dry inorganic material as the acid-neutralizing coadditive may also allow for the beneficial trapping of small amounts of moisture and thereby reduce or delay hydrolysis of the phosphite. The most preferred use of a calcined hydrotalcite appears to considerably reduce or delay hydrolysis of the liquid phosphite.

[0104] Again, without wishing to be constrained by theory, it is known that within a class of materials, for example, linear polyethylene, solubility of the liquid phosphite is inversely correlated with the density and percent crystallinity of the polymer. For example, a higher density polyethylene will have a higher crystalline content and thus lower amorphous content than a lower density polyethylene. The higher density, and thus lower amorphous content will generally be correlated with a lower solubility of the liquid phosphite. The higher density of a linear polyethylene will also generally be correlated with a lower diffusion coefficient of the liquid phosphite and a lower WVTR. As there can be other effects on solubility, diffusion, and WVTR including crystalline morphology, the First and Second carriers have been defined by solubility of the liquid phosphite.

Examples

[0105] The solubilities of liquid phosphite antioxidants suitable for practising the present invention were measured in several polymers.

[0106] Seven grades of polymers relevant to the current invention, encompassing a range of densities, MFRs, structures and monomers, were selected for testing. Surpass CCs757-A (HDPE) was obtained from NOVA Chemicals (Calgary, Alberta). Petrothene GA502024 (LLDPE) and Petrothene NA21900 (LDPE) were obtained from LyondellBasell Industries (Houston, USA). Vistamaxx 6502 (ethylene-propylene copolymer) and Escorene Ultra LD 768.MJ (EVAc) were obtained from ExxonMobil Chemical Corporation (Houston, USA). Engage XLT 8677 (ethylene-octene copolymer) and Versify 4301 were obtained from The Dow Chemical Company (Michigan, USA). A summary of key properties of the tested polymers can be found in Table 1.

[0107] The solubilities of liquid phosphite antioxidants Weston 705T, Doverphos LGP11 and Doverphos LGP12 were measured in each of the polymers.

[0108] Solubility testing was carried out according to the following procedure.

[0109] The pellets of each of the 7 polymers in Table 1 were compression molded into thin films according to Procedure C of Annex A1 in ASTM D4703-16. All the resins were compression molded at a temperature of 218 C., and cooled according to Procedure C. The compression molded films were cut using an Arbor Press into samples of dimensions 38.00 mm12.00 mm0.13 mm (thickness). A minimum of five samples from each polymer grade were prepared for each liquid phosphite tested. Separate glass jars were filled to within 5 mm of the top of the jar with either Weston 705T (W705T), Doverphos LGP11 or Doverphos LGP12. Samples of the different polymer films were suspended separately using stainless steel hangers so that they were in contact with the liquid antioxidant on all sides. The headspace of the jar was filled with dry nitrogen and the jars were carefully sealed in order to prevent hydrolysis of the liquid phosphite. Each set of polymer films was tested separately in its own jar with each liquid phosphite, as shown in Table 1. 6 of the polymer films were tested separately in the three different liquid phosphites, and 1 polymer film was tested in Weston 705T and LGP12 but not LGP11, for a total of 20 sets of data, each consisting of a minimum of 5 repeats.

[0110] The samples were aged in an oven at 45 C. and removed at regular intervals of time for gravimetric and FTIR testing. The samples were first wiped carefully and gently with a cloth soaked with acetone in order to remove any liquid phosphite on the surface of the film and then gently dried with a paper towel. The samples were then weighed and then tested by Fourier Transform Infrared Spectroscopy (FT-IR) in transmission mode. FTIR was used to confirm that the absorbed liquid phosphites had not hydrolyzed or oxidized. The concentration of the absorbed liquid phosphite in the samples was determined gravimetrically.

[0111] Tested samples were returned to the jars of liquid phosphite, the headspace was again blanketed in dry nitrogen and exposure was continued at 45 C. in the oven. The time the samples spent outside of the oven for testing was minimized. Samples were removed and tested at regular intervals in this manner until the completion of the testing regime. The testing interval was daily for the first week, every other day for the following week, then weekly for the remainder of the first month and then biweekly until the completion of testing. Completion of the testing regime varied for each polymer-liquid phosphite pair and was determined based on when the system reached equilibriummeaning that the polymer film no longer gained weight in a minimum of three successive testing intervals. High-performance liquid chromatography (HPLC) was carried out on the liquid phosphite remaining in the jars at the end of the testing regime. HPLC results provided additional confirmation that the liquid phosphite did not hydrolyze during the course of the testing regime.

[0112] The results in Table 1 show that Petrothene NA219000 (an LDPE), Petrothene GA502024 (an LLDPE) and Surpass CCs-757 (an HDPE) are suitable polymers for the First Carrier of the present invention. Weston 705T has a solubility of less than 5%, Doverphos LGP11 has a solubility of less than 3%, and Doverphos LGP12 has a solubility of less than 8% in these First Carrier polymers at 45 C.

[0113] The results also show that the Vistamaxx 6502, Engage XLT 8677, Escorene Ultra LD 768.MJ and Versify 4301 show much higher solubilities of the liquid phosphites. These three polymers were listed as suitable polymers for the Second Carrier of the immiscible polymer blend of the masterbatch of the present invention. Doverphos LGP11 has a solubility of greater than 12% in Vistamaxx 6502, Engage XLT 8677, and Escorene Ultra LD 768.MJ. Doverphos LGP12 has a solubility of greater than 17% in Vistamaxx 6502, Engage XLT 8677, Escorene Ultra LD 768.MJ, and Versify 4301. Weston 705T has a solubility of greater than 30% in Vistamaxx 6502, Engage XLT 8677, Escorene Ultra LD 768.MJ, and Versify 4301.

[0114] This data is useful in consideration of the subsequent examples and comparative examples of the present invention. It is understood that solubility data is dependent on the method of preparation of the polymer films because, for example, the rate of cooling or annealing can affect the crystalline structure and crystalline content of semi-crystalline polymers. Thus the presented data has been repeated under the controlled conditions described herein and accurately reflects the solubility of the liquid phosphites under these described conditions.

TABLE-US-00001 TABLE 1 Polymer Type [00001]$\begin{array}{c}\mathrm{MFI}*\\ \left(\frac{g}{10\min }\right)\end{array}$ [00002]$\begin{array}{c}\mathrm{Density}*\\ \left(\frac{g}{{\mathrm{cm}}^3}\right)\end{array}$ Crystallinity ** (%) W705T solubility *** (%) LGP11 solubility *** (%) LGP12 solubility *** (%) Surpass HDPE 7.0 0.957 65 3.1 0.36 2.4 0.29 7.5 1.59 CCs-757 Petrothene LLDPE 2.0 0.918 20 4.7 0.43 1.9 0.14 5.9 1.40 GA502024 Petrothene LDPE 10.0 0.923 30 3.4 0.22 2.1 0.26 6.3 1.11 NA219000 Vistamaxx Propylene- 21.0 0.865 44.1 0.48 12.6 0.25 22.1 1.86 6502 ethylene copolymer Versify Propylene- 25.0 0.868 1.3 31.8 0.67 N/A 18.0 0.83 4301 ethylene copolymer Engage Ethylene- 0.5 0.870 8 44.9 0.64 12.9 0.27 23.6 0.25 XLT 8677 Octene copolymer Escorene EVA 2.3 0.952 Not 51.5 0.66 12.9 0.20 17.4 0.68 Ultra LD copolymer calculated 768.MJ * MFR and density values are quoted from suppliers' datasheets. ** % Crystallinity was estimated by Differential Scanning Calorimetry (DSC). The percent crystallinity was calculated based on the measured enthalpy and a theoretical heat of fusion for a 100% crystalline polyethylene (293 J/g). *** Solubility was calculated as: S = ((W.sub.F W.sub.I) / W.sub.F) 100 Where, S = Solubility in %; W.sub.F = final weight of the exposed sample; W.sub.I = initial weight of the polymer film. Solubility values were not corrected for crystallinity. The solubility values represent an average of five samples. The standard deviation of the five samples is reported as the value.

[0115] A masterbatch composition according to the invention (Example E10) was prepared according to the following procedure.

[0116] 6.6 lbs of HDPE (Nova Chemicals Surpass CCs757-A) as the First Carrier, 2.0 lbs of an ethylene-propylene elastomer (ExxonMobil Chemical Company Vistamaxx 6502) as the Second Carrier, 1.0 lbs of liquid phosphite antioxidant (SI Group, Weston 705T) and 0.4 lbs of dehydrated hydrotalcite (Kyowa Chemical Industry Company DHT-4C) as the acid neutralizing coadditive were compounded on a Coperion ZSK30 mm, 36 length/diameter (L/D) twin-screw extruder equipped with a high-shear mixing screw, as is known in the art. Surpass CCs757-A (HDPE) was received in pellet form and was ground to a 12 Mesh top size prior to compounding. The Vistamaxx 6502 was not ground and was used in pellet form as received. The HDPE, elastomer and hydrotalcite were pre-weighed, dry blended and dosed to the extruder via a loss-in-weight feeder, as is known in the art. The loss in weight feeder doses the extruder indirectly, through a vertical auger which is fitted closely to the end of the loss in weight feeder and to the feed throat of the twin screw extruder. The liquid phosphite antioxidant was fed via a calibrated liquid feeder, directly to the vertical auger. The vertical auger was also fitted to allow for the addition of gaseous nitrogen at a volume sufficient to substantially displace air and any associated humidity from the feed to the extruder.

[0117] The extruder conditions were set to run at 250 RPM, with barrel zone temperatures of 100 C. in the feed zone increasing zone by zone to 180 C. in the last barrel zone and extrusion die. The measured temperature of the melt was 179 C. at the exit of the extruder. Pellets were formed on an underwater pelletizer and dried by a spin dryer as is known in the art. The masterbatch pellets were found to have a moisture content of less than 0.1%. The pellets were dry to the touch and free flowing.

[0118] It should be noted that the foregoing compounding method in a twin-screw extruder represents a common method of preparing masterbatches, but is by no means the only method known in the art. Masterbatches of the current invention could be made on twin screw extruders with different feeding and dosing methodologies known in the art, and could be made on other compounding equipment known in the art.

[0119] Approximately 200 grams of masterbatch pellets were exposed, uncovered in a petri dish in an environmental chamber under conditions of 45 C. and 80% relative humidity (RH). Samples were removed periodically, ground for ultrasonic extraction in cyclohexane and tested for Weston 705T content by HPLC. HPLC quantification was carried out on a Waters 2695, equipped with a Nova-Pak C18, 4 m, 3.9150 mm (Part No. WAT086344) column and a Waters 2487 UV-Vis detector and using an ethanol, methanol, isopropyl alcohol, and water mixture as the mobile phase. A calibration curve for quantification was developed using the same lot of W705T used for the production of the masterbatch. The calibration curve fit showed a correlation coefficient of >0.999 and relative standard deviation of <1%. It should be noted that active (unexposed, unhydrolyzed, unoxidized) Weston 705T exhibits 4 distinct peaks representing different components of the liquid phosphite. Any reduction in content of measured Weston 705T peaks over time in the exposed samples could be quantified and ascribed to hydrolysis or other unwanted reactions of the Weston 705T components.

[0120] The results showing the active Weston 705T content in the masterbatch sample E10 as a function of time are found in Table 2. The masterbatch sample E10 was found to have good hydrolytic stability. After 98 days of exposure at 45 C. and 80% RH, more than 85% of the original Weston 705T was still active.

[0121] Sample E10 was dry blended at 1.2% letdown with 98.8% of Nova Chemicals Novapol PF-0118-A LLDPE. This dry blend was extruded on a Lung-Meng LM/AH42-MI blown film line fitted with a single layer 4-inch die with 2.7 mm die gap. 50-micron film was blown and compared visually for gels with a reference film of 100% Novapol PF-0118-A resin produced under identical conditions. The purpose of this comparison was not to compare the stabilization provided by the antioxidant (base resin is already stabilized) but to understand if the First or Second Carrier resins would contribute to gels in the film. The comparison showed no difference in the level of gels in the two films.

[0122] For purposes of comparison, masterbatch compositions comprising neither a second carrier nor an inorganic solid coadditive (Comparative Examples CE1, CE2, and CE3) were prepared as follows.

[0123] 0.5 lbs of Weston 705T was compounded with 9.5 lbs of Surpass CCs757-A (ground to 12 mesh), Petrothene GA502024 (ground to 12 mesh top size) and Petrothene NA 219000 (ground to 12 mesh) to produce masterbatches labelled as CE1, CE2 and CE3 respectively. A second, immiscible carrier was not used, nor was an acid neutralizing coadditive. Compounding and testing procedures were carried out according to the method described for Example E10.

[0124] Results are tabulated in Table 2. Even at 5% loading of liquid phosphite the CE1, CE2, and CE3 masterbatches exhibited poor shelf life, as indicated by the rapidly decreasing active content of liquid phosphite measured by HPLC. In addition, the CE1 and CE3 pellets already felt slightly sticky and greasy to the touch, respectively, at the time of manufacture, indicating incomplete incorporation of the liquid phosphite or rapid migration of the liquid phosphite to the surface of the pellets.

TABLE-US-00002 TABLE 2 Example Comparative Examples Formulations (wt %) E10 CE1 CE2 CE3 Surpass CCs757-A 66.0% 95.0% (HDPE, ground) Petrothene GA502024 95.0% (LLDPE, ground) Petrothene NA 219000 95.0% (LDPE, ground) Vistamaxx 6502 (pellet) 20% Weston 705T 10.0% 5.0% 5.0% 5.0% DHT-4C 4.0% Results E10 CE1 CE2 CE3 Pellet feel to touch at Time zero dry slightly dry greasy sticky Active phosphite content (%) as measured by HPLC after exposure at 45 C. and 80% RH Day 0 9.9% 5.1% 5.4% 5.5% Day 7 8.5% 0% 0% 0% Day 35 8.2% Day 98 8.5%

[0125] Masterbatch compositions omitting essential components of the invention in turn (Comparative Examples CE7, CE21, CE22, CE26) were prepared as detailed below.

[0126] Comparative Example CE7 was prepared with neither a second carrier nor an inorganic solid coadditive. Comparative Example CE21 was prepared without an inorganic solid additive. Comparative Example CE22 was prepared without a second carrier. Comparative Example CE26 was prepared without a first carrier.

[0127] 10 lbs of comparative masterbatch compositions CE7, CE21 and CE22 were prepared according to the formulations in Table 3. CE7 was prepared as a comparative example incorporating 10% Weston 705T in HDPE (Surpass CCs757-A). CE21 was prepared as a comparative example incorporating 10% Weston 705T in an immiscible blend of Vistamaxx 65502 and HDPE (Surpass CCs757-A). CE22 was prepared as a comparative example incorporating 10% Weston 705T and 4% DHT-4C in HDPE (Surpass CCs757-A). CE26 was prepared as a comparative example incorporating 10% Weston 705T and 4% DHT-4C in Vistamaxx 6502. In this way the effects of the First Carrier (Surpass CCs757-A), Second Carrier (Vistamaxx 6502) and acid neutralizing coadditive (DHT-4C) could be assessed independently.

[0128] Compounding and testing procedures were carried out according to the method described in Example E10.

[0129] Testing results are also found in Table 3 and compared to those of Example E10.

[0130] Comparative Example CE7 shows that a masterbatch of 10% Weston 705T in the Surpass CCs757-A HDPE does not show good initial incorporation of the liquid phosphite, and the active liquid phosphite is fully consumed within a week of exposure to humid, warm conditions.

[0131] Comparative Example CE21 shows that the addition of the more amorphous Vistamaxx 6502 as a second carrier improves the initial incorporation of the liquid phosphite as shown by visual and tactile observation. However, the active liquid phosphite is fully hydrolysed within a week of exposure to humid, warm conditions.

[0132] Comparative Example CE22 shows that the addition of the DHT-4C acid neutralizer does not improve the initial incorporation of the liquid phosphite as evidenced by visual and tactile observation, however, it considerably improves the stability of the masterbatch in warm humid conditions. The Weston 705T is progressively consumed, but at a reduced rate as compared to Example CE21, and at a faster rate than example E10.

[0133] Comparative Example CE26 shows that the preparation of a 10% Weston 705T masterbatch with 4% DHT-4C in the highly amorphous Vistamaxx 6502 carrier provided an initially dry sample. However, the masterbatch did not provide for good shelf stability and the Weston 705T component hydrolyzed to 50% of its original content within 28 days.

[0134] Comparing CE7, CE21, CE22 and CE26 results with Example E10 we see that the use an immiscible polymer blend of two components exhibiting a disperse morphology as shown in FIG. 1, comprising a First Carrier characterized by a relatively lower solubility of the liquid phosphite and a dispersed Second Carrier characterized by a relatively higher solubility of the liquid phosphite, in combination with the use of an acid neutralizing coadditive, provides for the best incorporation and hydrolytic stability of the liquid phosphite.

TABLE-US-00003 TABLE 3 Example Comparative Examples Formulations (w t%) E10 CE7 CE21 CE22 CE26 Surpass CCs757-A 66% 90% 70% 86% 0% (ground) Vistamaxx 20% 20% 86% 6502 (pellet) Weston 705T 10% 10% 10% 10% 10% DHT-4C 4% 0% 0% 4% 4% Results Pellet feel to touch at Time dry greasy slightly greasy dry zero tacky Active phosphite content (%) as measured by HPLC after exposure at 45 C. and 80% RH Day 0 9.93 9.39 10.5 10.62 7.24 Day 7 8.53 0 0 8.21 6.87 Day 14 7.16 7.38 Day 21 5.58 Day 28 4.75 3.81 Day 35 8.19 Day 42 3.58 Day 70 0.85 Day 98 8.54 Day 120

[0135] Examples E9, E18, and E24 and Comparative Example CE8 were prepared with various polymers (in varying amounts) acting as the second carrier.

[0136] Compositions were prepared for compounding according to the formulations in Table 4. Compounding and testing procedures were carried out according to the method described in Example E10. Results are also tabulated in Table 4.

[0137] The recipes of E9 use a lower percentage of the second carrier polymer Vistamaxx 6502 as compared to E10. This led to a small amount of initial blooming on compounding. However, the formulation exhibited good resistance to hydrolysis on exposure to a warm humid environment.

[0138] Example E18 demonstrates the successful application of Engage XLT8677 as an alternative relatively lower density Second Carrier polymer. The masterbatch exhibits some initial blooming on compounding but exhibits good resistance to hydrolysis on exposure to a warm humid environment.

[0139] Example E24 demonstrates the successful use of Escorene LD768.MJ (an EVAC polymer) as an alternative Second Carrier polymer used in combination with the Surpass CCs757-A First Carrier polymer. The masterbatch exhibits no discernable blooming, good incorporation of the liquid phosphite and excellent resistance to hydrolysis on exposure to a warm humid environment.

[0140] Comparative Example CE8 demonstrates that Petrothene NA219000 (LDPE) is not a suitable Second Carrier of the present invention.

TABLE-US-00004 TABLE 4 Comparative Example Examples Formulations CE8 E9 E10 E18 E24 Surpass CCs757-A 76% 76% 66% 66% 60% (HDPE, ground) NA 219000 (10 MI, 10% .923 LDPE, ground) Vistamaxx 6502 10% 20% (pellet) Engage XLT8677 20% (pellet) Escorene LD768.MJ 20% (pellet) Weston 705T 10% 10% 10% 10% 10% DHT-4C 4% 4% 4% 4% 4% Results Pellet feel to touch at greasy slightly dry greasy dry Time zero greasy Active phosphite content (%) as measured by HPLC after exposure at 45 C. and 80% RH Day 0 10.48 10.8 9.93 9.1 10.29 Day 7 9.8 9.76 8.53 11.12 10.38 Day 14 10.31 Day 21 Day 28 10.47 Day 35 6.1 8.26 8.19 9.94 Day 42 10.36 Day 70 10.22 Day 98 0.65 9.93 8.54 10.92 Day 120

[0141] Examples E11, E23, E41, and E53 were prepared with various polymers acting as the first carrier.

[0142] Compositions were prepared for compounding according to the formulations in Table 5 in order to show the effect of different polymers as the First Carrier of the masterbatch of the current invention. Compounding and testing procedures were carried out according to the method described in Example E10. Results are also tabulated in Table 5.

[0143] E11, E41, and E53 showed no discernable blooming at the time of compounding. These masterbatches use substantially linear HDPE and MDPE and branched LDPE polymers respectively. E23 showed small levels of initial blooming on compounding. E23 uses a substantially linear LLDPE polymer. On exposure to a warm humid environment each of E11, E23, E41, and E53 showed good resistance to hydrolysis of the Weston 705T component.

TABLE-US-00005 TABLE 5 Examples Formulations E10 E11 E23 E41 E53 Surpass CCs757-A (HDPE, ground) 66% HD6706 (6.7 MI, .952 HDPE, 66% ground) GA502024 (2 MI, .918 LLDPE, 66% ground) NA 219000 (10 MI, .923 LDPE, ground) 66% LL8555.25 (6.8 MFR, .936, h- LLDPE, ground) 66% Vistamaxx 6502 (pellet) 20% 20% 20% 20% 20% Weston 705T 10% 10% 10% 10% 10% DHT-4C 4% 4% 4% 4% 4% Results Pellet feel to touch at Time very slight zero dry dry stickiness dry dry Active phosphite content (%) as measured by HPLC after exposure at 45 C. and 80% RH Day 0 9.93 9.33 9.97 9.50 9.68 Day 7 8.53 7.69 9.39 9.68 9.67 Day 14 9.85 9.61 Day 21 Day 28 9.41 9.98 9.59 Day 35 8.19 6.73 Day 42 9.72 9.78 Day 58 9.42 Day 70 9.22 9.59 Day 98 8.54 7.93 Day 120

[0144] Examples E30, E32, E33, and E54 and Comparative Examples CE34 and CE38 were prepared with various inorganic solid coadditives.

[0145] Compositions were prepared for compounding according to the formulations in Table 6 in order to show the effect of different acid neutralizing coadditives in the masterbatch. Compounding and testing procedures were carried out according to the method described in Example E10. Results are also tabulated in Table 6.

[0146] Example E30 demonstrates the successful application of Zinc oxide as the acid neutralizer of the present invention. The formulation showed no discernable blooming at the time of compounding, pellets felt dry and free flowing to the touch and on exposure to a warm humid environment the Weston 705T did not hydrolyze within 98 days.

[0147] Example E32 demonstrates the successful application of a blend of Zinc oxide and DHT-4C as the acid neutralizer of the present invention. The formulation showed no discernable blooming at the time of compounding, pellets felt dry and free flowing to the touch and on exposure to a warm humid environment the Weston 705T did not hydrolyze within 70 days.

[0148] Example E33 demonstrates the successful application of a blend of Zinc oxide and DHT-4V as the acid neutralizer of the present invention. The formulation showed no discernable blooming at the time of compounding, pellets felt dry and free flowing to the touch and on exposure to a warm humid environment the Weston 705T did not hydrolyze within 70 days.

[0149] Example E54 demonstrates the successful application of DHT-4V as the acid neutralizer of the present invention. The formulation showed no discernable blooming at the time of compounding; pellets felt dry and free flowing to the touch and on exposure to a warm humid environment the Weston 705T did not hydrolyze within 58 days.

[0150] Comparative example CE34 shows the zinc stearate has a negative effect as an additional additive in the composition of the current invention. More than 80% of the original Weston 705T content was hydrolyzed within 70 days of exposure to a warm humid environment.

[0151] Comparative example CE38 shows the unsuccessful application of zinc stearate as an acid neutralizer in the composition of the current invention. Zinc stearate is not an inorganic mineral, acid neutralizing coadditive as described in the current invention. More than 70% of the original Weston 705T content was hydrolyzed within 28 days of exposure to a warm humid environment.

[0152] In aggregate, these Examples show the beneficial application of certain inorganic mineral additives as acid neutralizing coadditives of the present invention. Comparative examples show the unsuccessful use of zinc stearate, as a replacement to the acid neutralizing coadditive of the present invention.

TABLE-US-00006 TABLE 6 Comparative Examples Examples E10 E30 E32 E33 E54 CE34 CE38 Formulations Surpass CCs757-A 66% 66% 66% 66% 66% 66% 66% (HDPE, ground) Vistamaxx 6502 20% 20% 20% 20% 20% 20% 20% (pellet) Weston 705T 10% 10% 10% 10% 10% 10% 10% DHT-4C 4% 2% DHT-4V 2% 4% Zoco 102 Zinc Oxide 4% 2% 2% 2% Faci ZnSt SP 2% 4% Results Pellet feel to touch Dry Dry Dry Dry Dry Dry Dry at Day 0 Active phosphite content (%) as measured by HPLC after exposure at 45 C. and 80% RH Day 0 9.9 7.9 10.4 9.2 10.0 10.0 9.0 Day 7 8.5 7.4 9.6 9.5 9.9 9.0 9.0 Day 14 7.3 9.9 9.3 9.4 8.3 Day 21 Day 28 10.0 9.3 9.7 9.7 2.8 Day 35 8.2 Day 42 7.4 10.0 9.5 8.9 0.06 Day 58 9.8 Day 70 10.0 9.7 2.2 0.00 Day 98 8.5 7.9

[0153] Examples E50, and E51 were prepared with varying concentrations of the liquid phosphite antioxidant.

[0154] Compositions were prepared for compounding according to the formulations shown in Table 7. Compounding and testing procedures were carried out according to the method described in Example E10. Results are also tabulated in Table 7.

[0155] Examples E50 and E51 demonstrate the successful application of the present invention to increasing concentrations of the liquid phosphite Weston 705T. The formulations showed no discernable blooming at the time of compounding; pellets felt dry to the touch at the time of compounding. The E51 pellets showed some slight agglomeration during compounding immediately after the pelletizer, but the loose agglomerate broke up easily on being transferred and did not show any re-agglomeration on repackaging and storage within the temperature controlled warehouse conditions. On exposure to a warm humid environment in the environmental chamber the Weston 705T in Examples E50 and E51 did not show significant hydrolysis within 58 days.

TABLE-US-00007 TABLE 7 Examples Formulations E50 E51 Surpass CCs757-A (ground) 51.00% 48% Petrothene NA 219000 (ground) 30.00% 30.00% Vistamax 6502 (pellet) Weston 705T 15.00% 18% DHT-4C 4.00% 4.00% Results Pellet feel to touch at Time zero dry dry, loose agglomerate, easily broken up. Active phosphite content (%) as measured by HPLC after exposure at 45 C. and 80% RH Day 0 14.3 17.9 Day 7 14.2 18.0 Day 28 14.2 17.4 Day 58 14.1 17.3

[0156] Examples E35, E36, and E37 were prepared in order to show the effect of the ratios of the First and Second Carriers on the method of the invention.

[0157] Compositions were prepared for compounding according to the formulations in Table 8. Compounding and testing procedures were carried out according to the method described in Example E10. Results are also tabulated in Table 8.

[0158] Samples were prepared for microscopy by microtoming at a temperature of 150 C. and sputter coated with C to a thickness of 12 nm. Samples were then analyzed by SEM.

[0159] Photomicroscopy by SEM showed that the Vistamaxx and Surpass polymers formed an immiscible polymer blend. Example E10, containing 20% Vistamaxx 6502, was characterized by a dispersed phase of Vistamaxx 6502 in the Surpass continuous phase, as shown in FIG. 1. Examples E35 and E36, containing 30 and 36% Vistamaxx respectively, were characterized by what appeared to be a co-continuous morphology of Vistamaxx and Surpass. Examples E37 showed an inverted phase morphology with respect to Example E10. Example E37 was characterized by a continuous Vistamaxx phase. In all of E10, E35, E36 and E37, the DHT-4C can be seen as a dispersed mineral particulate.

[0160] Examples E35, E36 an E37 demonstrates the successful application the present across a range of concentrations of the two carrier polymers. On exposure to a warm humid 5 environment in the environmental chamber the masterbatches E35 and E36 showed no significant hydrolysis of the liquid phosphite in 58 days of testing. Example E37 showed a decrease in active Weston 705 content from 8.71% to 7.64%. While not as shelf-stable as E35 and E36, Example E37 is still much more stable than single carrier systems E22 and E26.

TABLE-US-00008 TABLE 8 Examples Formulations E10 E35 E36 E37 Surpass CCs757-A (7 MI, .957 HDPE) 66.00% 56.00% 50.00% 40.00% Vistamaxx 6502 20.00% 30.00% 36.00% 46.00% (21 MFR, 0.865 g/cc) Weston 705T 10.00% 10.00% 10.00% 10.00% DHT-4C 4.00% 4.00% 4.00% 4.00% Results Pellet feel to touch at dry dry dry dry Time zero Morphology Disperse Co- Co- Inverted (Microscopy) Vistamaxx continuous continuous (Vistamaxx Continuous) Active phosphite content (%) as measured by HPLC after exposure at 45 C. and 80% RH Day 0 9.93 9.27 8.88 8.71 Day 7 8.53 8.53 7.84 8.12 Day 14 8.83 7.99 8.33 Day 28 9.26 8.66 7.93 Day 35 8.19 Day 42 8.94 8.21 7.53 Day 58 9.58 8.88 7.64 Day 98 8.54

[0161] Examples E45 and E49 and Comparative Examples CE27 and CE28 were prepared in order to show the effect of the acid-neutralizing coadditive and the Second Carrier on masterbatches of the present invention.

[0162] Compositions were prepared for compounding according to the formulations in Table 9. Compounding and testing was carried out according to the method described in Example E10.

[0163] Approximately 200 grams of masterbatch pellets were exposed, uncovered in a petri dish in an environmental chamber under conditions of 45 C. and 80% relative humidity (RH). Samples were removed periodically and tested for the hydrolyzed LGP11 content by HPLC. HPLC quantification was carried out on a Waters 2695, equipped with a Waters (Part No. WAT052805, Nova-Pak C8, 4 m, 3.9100 mm) column and a Softa (Model 300S) evaporative light scattering detector.

[0164] It should be noted that the LGP-11 could not be measured directly by this method and one of the hydrolysis products of LGP-11 was measured instead. The hydrolysis product exhibits a sharp peak. A calibration curve for quantification was developed and the method was found to have an accuracy of correlation coefficient of 0.999 and relative standard deviation of <1%. Results are also tabulated in Table 9.

[0165] Comparative Example CE27 showed poor hydrolytic stability. The LGP-11 was completely hydrolyzed within 7 days. This comparative masterbatch did not include an acid neutralizing coadditive.

[0166] Comparative Example CE28 showed improved hydrolytic stability as compared to Comparative Example CE27 but was found to still hydrolyze within 70 days in the aggressive exposure conditions of 45 C. and 80% RH. This comparative masterbatch did not include a Second Carrier.

[0167] Example E45 demonstrates the successful application of the masterbatch of the present invention. Example E45 shows reduced hydrolysis of the LGP11 as compared to Comparative examples CE27 and CE28.

[0168] Example E49 demonstrates the successful application of the masterbatch of the present invention. Example E49 shows reduced hydrolysis of the LGP11 as compared to Comparative examples CE27 and CE28. Compared to Example E45, Example E49 shows a higher absolute concentration of hydrolyzed LGP11 as a function of time, but proportional to its higher initial concentration of LGP11 the level of hydrolysis is improved.

TABLE-US-00009 TABLE 9 Comparative Examples Examples Formulations CE27 CE28 E45 E49 Surpass CCs757-A (HDPE) 70.00% 86.00% 66.00% 51.00% VistamaxxM 6502 20.00% 20.00% 30.00% Doverphos LGP-11 10.00% 10.00% 10.00% 15.00% DHT-4C 4.00% 4.00% 4.00% Results Pellet feel to touch at Day 0 dry dry dry dry HPLC measurement of hydrolysis (%) after exposure at 45 C. and 80% RH Day 0 2.6 0.2 0.0 0.0 Day 7 10.0 3.7 0.5 0.9 Day 14 5.2 3.6 1.3 Day 21 3.4 5.2 Day 28 6.3 4.0 5.3 Day 35 3.8 5.4 Day 42 6.5 4.8 6.6 Day 70 9.3 Day 98

[0169] Examples E50, E51, E52 and E53 were prepared in order to show the effect of an alternate Second Carrier, the effect of the addition of an optional additional additive (a phenolic antioxidant), and the effect of a different acid-neutralizing coadditive on masterbatches of the present invention.

[0170] Compositions were prepared for compounding according to the formulations in Table 10. Compounding and testing was carried out according to the method described in Example E10.

[0171] Examples E50 and E51 demonstrates the successful application of Versify 4301 as an alternative Second Carrier polymer of the present invention. The masterbatches exhibit no blooming on compounding and good resistance to hydrolysis on exposure to a warm humid environment.

[0172] Example E52 demonstrates the addition of an optional additional additive as is known in the artin this case a hindered phenolic antioxidant. Masterbatch E52 incorporates the optional additional additive Irganox 1076 to the liquid phosphite masterbatch of the present invention. The masterbatch exhibits no blooming on compounding, and exhibits good resistance to hydrolysis on exposure to a warm humid environment.

[0173] Example E52 demonstrates the addition of the optional hindered phenol antioxidant as well as the use of an alternate inorganic solid coadditive of the present invention. The masterbatch exhibits no blooming on compounding and good resistance to hydrolysis on exposure to warm humid environments.

TABLE-US-00010 TABLE 10 Examples Formulations E50 E51 E52 E53 Petrothene GA502024 66.00% 51.00% 61.00% 61.00% (LLDPE) Vistamaxx 6502 20.00% Versify 4301 20.00% 30.00% 20.00% Weston 705T 10.00% 15.00% 10.00% 10.00% Irganox 1076 5.00% 5.00% Zoco 102 Zinc Oxide 4.00% 4.00% 4.00% DHT-4V 4.00% Results Pellet feel to touch at Day 0 dry dry dry dry Active phosphite content (%) as measured by HPLC after exposure at 45 C. and 80% RH Day 0 9.02 14.6 10.4 9.98 Day 7 8.97 13.7 10.1 9.43 Day 14 9.15 13.3 9.90 9.10 Day 21 9.20 13.3 9.85 9.35 Day 28 9.33 12.6 9.56 9.71 Day 35 9.09 13.5 9.54 8.94 Day 42 9.80 13.8 10.6 10.4 Day 70 9.23 13.5 9.86 9.75 Day 98 9.37 14.4 9.71 9.91

[0174] The words comprises/comprising and the words having/including when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0175] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.