WO2008103560A2

WO2008103560A2 - Improved process for the manufacture of polymer additive granules containing silica antiblock agents

Info

Publication number: WO2008103560A2
Application number: PCT/US2008/053283
Authority: WO
Inventors: John Semen
Original assignee: Albemarle Corporation
Priority date: 2007-02-20
Filing date: 2008-02-07
Publication date: 2008-08-28
Also published as: WO2008103560A3; TW200900442A

Abstract

Polymer additive granules are formed by combining together (i) a silica powder and (ii) a fatty component, to form a preblend; combining the preblend with at least one polymer additive, to form a powder blend; combining a processing solvent and the powder blend to form a mixture; and granulating the mixture to form granules.

Description

IMPROVED PROCESS FOR THE MANUFACTURE OF POLYMER ADDITIVE GRANULES CONTAINING SILICA ANTIBLOCK AGENTS

TECHNICAL FIELD

[0001] This invention relates to processes for producing polymer additives in granular form.

BACKGROUND

[0002] It is well known to use pellet mills, and similar granulating equipment, to make polymer additive packages in a convenient-to-use granular form.

[0003] Dunsky (U.S. Pat. No. 5,846,656) teaches the utility of utilizing fatty derivatives in pellet-mill granulation processes for the purpose of facilitating the formation of the granules. However, this prior art teaches neither the utilization of the silica/fatty derivatives in a preblend form nor the utilization of processing solvents, much less the use of both preblend and processing solvent concomitantly, in a pellet-mill granulation process. Moreover, Dunsky does not address granules that contain silica antiblock compounds.

[0004] Semen (U.S. Pat. No. 6,821,456; U.S. Pat. No. 6,800,228; U.S. Pat. No. 6,596,198; U.S. Pat. No. 6,515,052; U.S. Pat. No. 6,126,863; U.S. Pat. No. 6,126,862; U.S. Pat. No. 6,056,898; and U.S. Pat. No. 5,846,656) generally teaches the advantages of using processing solvents in pellet-mill granulation processes.

[0005] Tonnvik, et al. (WO 99/54396) teach a process of making a polymer additive granulate composition containing a micronized silicic acid or an aluminosilicate as antiblocking agents.

[0006] However, the manufacture of such granules with pellet mills becomes a severe challenge when one of the components of the additive package is a silica particulate intended for imparting antiblock properties to the polymer product. Such silica particulates often are synthetic, amorphous, precipitated silicas having high pore volume, small particle size, and other features which promote low bulk density properties. Although preferred for good antiblock properties, these low-bulk-density silicas vastly increase the costs of granulating the additive package by, for example, decreasing the capacity (maximum processing rate) of the pellet mill equipment or increasing the number of powder blending batches. Therefore, the need for new, effective processes of manufacturing such granules continues to exist. SUMMARY OF INVENTION

[0007] The present invention addresses this need in an efficient and effective manner by providing, amongst other things, new process technology for producing polymer additive packages in a convenient-to-use granular form when one of the components of the additive package is a silica particulate intended for imparting antiblock properties to the polymer product. In one embodiment of the invention, both a processing solvent and an intensively-mixed preblend is employed in the blend to be pelletized. This new process technology has been found to readily produce desired products in less time than known prior systems, thus decreasing the cost involved in the pelleting process. [0008] The processes of this invention produce granules, which when compounded by extrusion or similar processes with thermoplastic polymers, produces polymers having improved mechanical, physical, and chemical properties. Typically, the granules may be comprised of one or more of the following: silica antiblock agents, which inhibit sheet and film forms of the polymer from adhering or sticking together; a fatty acid component, which is desirable for imparting antistatic properties to film forms of the polymer, improving the antiblock performance of the silica component in the polymer films, and improving mold-release performance in the manufacture of polymer parts by injection molding, sheet thermoforming, and similar fabrication methods; and antioxidants, which are desirable for preventing the degradation of the mechanical and physical properties of the polymer both during compounding/thermal-forming of polymer articles and during the use-life of the polymer article.

[0009] An embodiment of this invention is a process for making polymer additive packages in a convenient-to-use granular form, which process comprises combining together (i) a silica powder and (ii) a fatty component, to form a preblend; combining the preblend with a polymer additive, to form a powder blend; combining a processing solvent and the powder blend to form a mixture; and granulating the mixture to form granules.

In other embodiments of the invention this process further comprises removing at least a portion of the processing solvent from the granules to form dried granules. Still other embodiments of the invention also further comprise separating under-sized particles from the dried granules to thereby produce dried granules of a pre-selected average size. In some processes of the invention, the amount of fatty component used to form the preblend is in the range of about 15 wt% to about 95 wt% of the preblend. In some embodiments of the invention, the fatty component is either a single compound or a mixture of compounds selected from the group consisting of a fatty alcohol having from 12 to 22 carbon atoms in the molecule or an ester thereof and a fatty acid having from 12 to 22 carbon atoms in the molecule or an ester, glycerol ester, or amide of the same, where the amides of fatty acids include primary amides, secondary amides, and secondary bis-amides, in which the functional group attached to the nitrogen of the secondary amides and secondary bis- amides contain 1 to 22 carbon atoms.

[0010] In certain embodiments of this invention, the polymer additive comprises at least one antioxidant component additive which comprises a phenolic antioxidant, a phosphite antioxidant, or a combination thereof and further comprises a sulfur-based antioxidant synergist in the range of from about 20 wt% to about 60 wt% of the total weight of the antioxidant component. The polymer additive may further comprise one or more additional additives selected from an acid neutralizer, a nucleating agent, a clarifier, a lubricant and mold-release agent, an antistat, a processing aid, a filler, or any combination of two or more of the foregoing.

[0011] The aerated bulk density of the preblend in certain embodiments of this invention is at least 25% higher than the aerated bulk density of the silica powder, preferably at least 50% higher than the aerated bulk density of the silica powder, and more preferably at least 100% higher than the aerated bulk density of the silica powder. The amount of the processing solvent in certain embodiments of this invention is in the range of about 3 wt% to 30 wt% of the total weight of the mixture in (c). The processing solvent of some particular embodiments of the invention comprises a hydrocarbon containing in the range of 3 to 7 carbon atoms in the molecule, or yet, in other embodiments, is selected from either cyclohexane or isohexane.

[0012] These and other embodiments and features of this invention will be still further apparent from the ensuing detailed description and appended claims.

FURTHER DETAILED DESCRIPTION OF THE INVENTION

[0013] The instant invention is a process for making granules containing silica antiblock agent and other polymer additives, the process performed by (1) combining the silica with a fatty component, to form a preblend; (2) combining at least a portion of the preblend with other common polymer additives, which include one or more additives selected from an acid neutralizer, a nucleating agent, a clarifier, a lubricant and mold-release agent, an antistat, a processing aid, a filler, or any combination of two or more of the foregoing; (3) combining a hydrocarbon processing solvent and at least a portion of the powder blend to form a mixture; (4) granulating at least a portion of the mixture of processing solvent and powder blend, e.g., with a pellet mill or similar granulation equipment. Typically, at least a portion, and more usually most, if not all, of the processing solvent is removed from the granules by a suitable drying process. Desirably ,_the under-sized particles are removed from the dried granules with a sieving, or similar, size classifying process to give the finished granules of a pre-selected average size.

[0014] For convenience, as used anywhere herein, the term "silica antiblock agent" (whether in the singular or plural and whether or not preceded by other modifying terms, such as "novel", "one or more", "at least one", etc.) refers to any silica powder which has an aerated bulk density of less than about 0.3 g/ml. For example, suitable silica powder would include synthetic silica powders, natural silica powders, or a mixture thereof. Moreover, those skilled in the art of antiblock agents will appreciate that the average particle size of the silica powders will be relatively small, typically in the range of about 0.5 micron to about 10 micron.

[0015] For convenience, as used anywhere herein, the term "fatty component" (whether in the singular or plural and whether or not preceded by other modifying terms, such as "novel", "one or more", "at least one", etc.) refers to a component that is selected from the group consisting of: a fatty acid, a fatty alcohol, a fatty acid amide, a fatty acid ester, an ester of a fatty alcohol, or a combination of two or more of the foregoing. For example, suitable fatty acids would include dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, oleic acid, linoleic acid, alpha- linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, erucic acid, or a combination of two or more of these, and the like, while examples of suitable fatty acid esters would include any ester, or glycerol ester, of the foregoing fatty acids, or a combination of two or more of these, and the like. Examples of suitable fatty acid amides would include primary amides, secondary amides, and secondary bis-amides, in which the functional group attached to the nitrogen of the secondary amides and secondary bis- amides contain 1 to 22 carbon atoms. Examples of suitable primary amides include dodecanamide, tetradecanamide, hexadecanamide, octadecanamide, eicosanamide, docosanamide, oleamide, linoleamide, alpha-linolenamide, arachidonamide, eicosapentaenamide, docosahexaenamide, erucamide, or a combination of two or more of these, and the like. Examples of suitable secondary amides include oleyl palmitamide, stearyl erucamide, and the like. Examples of suitable secondary bis-amides include ethylene bis-stearamide, ethylene bis-oleamide, and the like. Examples of suitable fatty alcohols would include 1-dodecanol, myristyl alcohol, cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, isostearyl alcohol, elaidyl alcohol, oleyl alcohol, linoleyl alcohol, elaidolinoleyl alcohol, linolenyl alcohol, elaidolinolenyl alcohol, ricinoleyl alcohol, arachidyl alcohol, behenyl alcohol, erucyl alcohol, or any ester thereof, or a combination of two or more of these, and the like. The fatty component is preferably in the form of a powdered solid or a melted liquid.

[0016] The process of this invention produces this special class of additive granules (i.e., granules that contain silica antistat, antioxidants, and fatty derivatives) at substantially faster granulation rates than other pelleting-type processes known in the prior art. Thus, the manufacturing costs of such granules are substantially reduced compared with processes of the prior art.

[0017] While not wishing to be bound by theory, it is believed that the granulation-rate improvements obtained by the process of this invention result from a synergistic densification of the feed powder (i.e., the powder entering the pellet mill for granulation) resulting from the preblending and the solvent-processing aspects of the granulation process. Specifically, it is believed that the densification of the silica raw material powder that occurs in the preblending operation results because the fatty derivative component, at least in part, coats out on the surface of the silica particles, and this coating process both densifies the silica (through agglomeration, static-charge-dissipation, and other mechanisms) and imparts a hydrocarbon-like surface to the silica particles, and the processing solvent is believed to wet-out on the coated silica particles, thereby densifying the feed mixture by imparting cohesion among the various particles (including coated silica particles and antioxidant particles) in the feed blend. This theory is consistent with the preblend and the solvent-processing features of the process of this invention acting synergistic ally to increase the density of the feed blend, and therefore the granulation rate. That is, the densification by the solvent is grossly diminished if the preblending feature is omitted, and the overall densification is grossly diminished if the solvent-processing feature is omitted. [0018] The "preblend" of the instant invention typically contains between about 15 wt% and about 95 wt% of the fatty component. Moreover, the aerated bulk density of the preblend is desirably at least 25% higher than that of the neat silica powder, and preferably at least 50% higher, and more preferably at least 100% higher. The preblend is usually prepared in an intensive mixer. Those skilled in the art of operating intensive mixers will appreciate that a wide variety of intensive mixing conditions, including the rotor speed, the residence time, and the temperature of the mixer jacket, need to be adjusted appropriately to achieve the required aerated bulk density properties.

[0019] Moreover, those skilled in the art will appreciate that the combining may be done with the fatty component introduced into the intensive mixer as either a powdered solid or a melted liquid. The fatty component of the preblend may be a single compound, or a mixture of compounds, selected from one or more of the following: a fatty acid having from 12 to 22 carbon atoms in the molecule or an ester (or glycerol ester) or amide of the same, and a fatty alcohol having from 12 to 22 carbon atoms in the molecule or an ester thereof.

[0020] Further, the step of combining together a silica powder and a fatty component in processes of this invention can typically be carried out in a number of ways. For example, suitable combining processes would include intensively blending the silica with the solid fatty powder component batchwise in a Henschel Mixer®, a cone blender, a Littleford W- Series intensive blender, or similar equipment; alternatively, the fatty component may be melted and then introduced as a liquid in such blending equipment. In another variation, the formation of the preblend may be effected in continuous intensive mixers, such as a Schugi Flexomix (available from Hosokawa Bepex Corp.). In any event, such combining should be carried out under conditions sufficient to ensure that the combined components effectively form a preblend with the desired aerated bulk density properties. [0021] The step of combining the preblend with at least one polymer additive in processes of this invention can typically be carried out in a number of ways. For example, one suitable combining process would include the steps: 1) Combining the preblend and the other polymer additives in a ribbon blender; 2) dry blending the powders sufficiently to homogenize the powder particles; and preferably 3) while continuing blending, adding the processing solvent to the powders by spraying the solvent (through spray nozzles) onto the blending powder bed. Alternatively, such combining can be accomplished with other kinds of blending equipment, such as a tumble blender, a pug mixer, a kneader, an Extrud- ® O-Mix Mixer (available from Hosokawa Bepex Corp.)_* and a wide variety of similar equipment. In any event, such combining should be carried out under conditions sufficient to ensure that the final mixture is reasonably homogeneous.

[0022] As indicated above, the step of combining the processing solvent with all or at least a portion of the powder blend formed by combining the preblend with at least one polymer additive can be carried out without interruption such as by spraying the processing solvent onto the powder blend while still continuing to mix the powder blend. Alternatively, such powder blend of preblend and polymer additive(s) can be formed as a dried powder which is then mixed with processing solvent. In this case, the dried powder and the processing solvent can be concurrently fed into a suitable mixing device or the dried powder can be added to the processing solvent, preferably, with mixing and desirably by portion wise addition of the processing solvent. Combinations of these procedures are also possible. The preferred method, however, is to spray the processing solvent onto the dried powder composed of an intimate mixture of the preblend and one or more polymer additives. It will be noted that it is preferred to employ polymer additives which are themselves in a dry, i.e., non- liquid, state. If a polymer additive is in liquid form, it is desirable that the liquid phase of the liquid polymer additive be a low boiling diluent or solvent which can be readily removed on heating the resultant mixture of the preblend and the liquid polymer additive with or without the further presence of the processing solvent.

[0023] The step of granulating the mixture to form granules in processes of this invention can typically be carried out in a number of ways. For example, the blend of the preblend, polymer additives, and processing solvent may be shaped into cylindrical granules with a flat-plate pellet mill, a ring-die pellet mill, a gear pelletizer, an Extrud-O- Mix® pelletizer, or similar equipment.

[0024] The step of removing at least a portion of the processing solvent from the granules to form dried granules in processes of this invention can typically be carried out in a number of ways. Those skilled in the art of antiblock agents will appreciate that various methods can be used to remove at least a portion of the processing solvent from the granules, such as applying appropriate heating to drive off the solvent, and that additional apparatus and/or technique optionally can be applied to assist in the driving off at least a portion of the processing solvent, such as applying a vacuum. For example, suitable processes of removing at least a portion of the processing solvent from the granules to form dried granules include the use of box ovens, tray driers, fluid bed dryers, and the like. In any event, the drying process should be run under conditions appropriate for removing essentially all of the processing solvent. Those skilled in the art will recognize that drying is preferably, to less than about 1500 ppm residual solvent, more preferable less than about 1000 ppm, depending on various considerations such as the volatiles specifications of antioxidant powder raw materials and other polymer additives, the preferred shelf life of the antioxidant components, and possibly other components, in the granules, and other considerations. In any event, the drying operation is normally performed under dry nitrogen atmosphere to prevent undesirable oxidation of the antioxidants and possibly other additive components. Moreover, the temperature at which the drying process is run must be selected sufficiently low to prevent the melting of any of the additive components in the granule (i.e., to maintain the desired granular morphology). [0025] The step of separating under-sized particles from the dried granules in processes of this invention can typically be carried out in a number of ways. For example, the undesirable under-sized particles may be removed by dry-sieving with screens, in a fluidized-bed apparatus, or by similar methods well-known in the art. [0026] The composition of the granules of the present invention, which is determined by the relative portions of ingredients added in the powder blend step, which is step 2 of the process above, is in the range of about 15 wt% to about 50 wt% silica, 5 wt% to about 60 wt% fatty component, and 10 wt% to about 80 wt% of an antioxidant component. The antioxidant component may be either a single hindered phenol, a single phosphorous- based secondary antioxidant, or a mixture of two or more compounds selected from the combination of hindered phenols and phosphorous-based secondary antioxidants. Optionally, sulfur-based antioxidant synergist, such as dilaurylthiodipropionate and/or distearylthiopropionate, for example, may be used as part of the antioxidant component, in which the synergist comprises from about 20 wt% to about 60 wt% of the antioxidant component. Also, optionally, the composition of the granule may include from 0 wt% to about 50 wt% of other polymer additive components.

[0027] Examples of suitable phosphite antioxidant component include tris(2,4-di-t- butylphenyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol-di -phosphite, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite, bis(2,4-dicumylphenyl)- pentaerythritol diphosphite, or a combination of two or more of these, and the like. Examples of suitable phenolic antioxidant component include 4,4'-methylenebis-(2,6-di- tert-butylphenol), l,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,5-di-tert-butylhydroquinone, l,3,5-tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydro-cinnamate)]methane, octadecyl 3,5-di- t-butyl-4-hydroxyhydrocinnamate, 2,6-di-t-butyl-N,N-dimethylamino-p-cresol, 1,3,5- tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-l,3,5-triazine-2,4,6-(lH,3H,5H)-trione, thiodiethylenebis-(3,5-di-t-butyl-4-hydroxyhydrocinnamate), or a combination of two or more of these, and the like.

[0028] The other polymer additive components in the present invention could comprise any of a vast number of particulate polymer additives. Preferably, the polymer additive comprises one or more additives selected from an acid neutralizer, a nucleating agent, a clarifier, a lubricant and mold-release agent, an antistat, a processing aid, a filler, or any combination of two or more of the foregoing.

[0029] Examples of suitable acid neutralizers include hydrotalcite (magnesium aluminum carbonate hydrate), calcium stearate, zinc stearate, dibutyl tin maleate, or a combination of two or more of these, and the like. Examples of suitable nucleating agents include sodium benzoate, proprietary compositions under the trade names

HYPERFORM® HPN-68L and HYPERFORM® HPN-20E (Milliken Chemical Co.), sodium 2,2'-methylene-bis-(4,6-di-t-butylphenyl) phosphate, or a combination of two or more of these, and the like. Examples of suitable clarifiers include l,3:2,4-bis(3,4-di- methylbenzylidene) sorbitol, 1,3:2,4 dibenzylidene sorbitol, 1,3:2,4 dipara- methyldibenzylidene sorbitol, or a combination of two or more of these, and the like. Examples of suitable lubricants and mold-release agents include fatty acids such as butanoic acid, hexanoic acid, octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, oleic acid, linoleic acid, alpha-linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, erucic acid, or any amide, ester, or glycerol ester thereof; fatty alcohols such as 1-dodecanol, myristyl alcohol, cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, isostearyl alcohol, elaidyl alcohol, oleyl alcohol, linoleyl alcohol, elaidolinoleyl alcohol, linolenyl alcohol, elaidolinolenyl alcohol, ricinoleyl alcohol, arachidyl alcohol, behenyl alcohol, erucyl alcohol or any ester thereof; or a combination of two or more of these, and the like. Examples of suitable antistats include glycerol monostearate, glycerol distearate, glycerol monooleate, glycerol dioleate, or a combination of two or more of these, and the like. Examples of suitable processing aids include mixtures of vinylidene fluoride-hexafluoropropyene copolymer, polyethylene oxide, talc, calcium carbonate, proprietary compounds sold under the trade names DYNAMAR® E- 19106,

DYNAMAR® FX-5920, DYNAMAR® FX-5922, DYNAMAR® FX-9614, etc. by

Dyneon (a 3M company), Oakdale MN, and the like. Examples of suitable fillers include clays, micas, talc, or a combination of two or more of these, and the like. [0030] The "processing solvent" of the present invention can be that described previously by Semen in U.S. Pat. No. 6,821,456. The processing solvent used is preferably one in which the phenolic component used has a minimum solubility of about 5 grams per liter of processing solvent. Preferably, however, the processing solvent used is one in which the solubility of the phenolic component is limited. Thus, it is desirable to use a processing solvent in which the phenolic component has a maximum solubility of about 300 grams of phenolic component per liter of processing solvent, with a maximum solubility of about 200 grams per liter being more desirable, and a maximum solubility of about 100 grams per liter being most desirable. Such solubilities are preferably measured at a temperature in the range of from about 20 degrees C to about 70 degrees C, but most preferably are measured at the temperature at which the paste is formed into granules. It should be noted that even when using phenolic component/processing solvent pairs in which the solubilities are greater than the maximum values given above, it is possible, in principle, to form granules or pellets according to the process of this invention. Adjustment of the solvent level can be performed, in most cases, to yield a suitable paste. The processing solvent used preferably will be a processing solvent that can be vaporized, preferably at ordinary atmospheric pressure, at a temperature below the lowest melting point or initial melting temperature of the mixture of the components of the additive package. Non-limiting examples of suitable processing solvents would include, but are not limited to, hydrocarbons, e.g., alkanes, cycloalkanes, alkenes, cycloalkenes, and aromatic hydrocarbons; halogenated hydrocarbons; ethers; alcohols; and ketones. A few illustrative examples of such solvents include pentane, hexane, isopentane, 2- methylheptane, methylcyclopentane, benzene, chloroform, methylene chloride, diethyl ether, 2-ethyoxypropane, tetrahydrofuran, l,4dixoane, ethyl alcohol, isopropyl alcohol, acetone, methylethyl ketone, cyclohexane, isohexane, toluene, xylene, methylcyclohexane, hexane, heptane, cyclopentane, or a combination of two or more of these, and the like. Preferred processing solvents are saturated hydrocarbons containing about 5 to about 7 carbon atoms, with cyclohexane and isohexane being especially preferred. Another preferred group of processing solvents is comprised of acetone, anisole, 1-butanol, 1- butanol, butyl acetate, tert-butylmethyl ether, cumene, dimethyl sulfoxide, ethanol, ethyl acetate, ethyl ether, ethyl formate, heptane, isobutyl acetate, isopropyl acetate, methyl acetate, 3-methyl- 1-butanol, methylethyl ketone, methyl isobutyl ketone, 2-methyl-l- propanol, pentane, 1-pentanol, 1-propanol, 2-propanol, propyl acetate, tetrahydrofuran, and mixtures of at least two such solvents. The concentration of the processing solvent in the powder blend is about 3 wt% to about 30 wt%. Those skilled in the art will appreciate that the appropriate solvent concentration will vary depending on the composition of the granules, type and operating conditions of the pelleting equipment, and other conditions. [0031] The following examples are presented for purposes of illustration, and are not intended to impose limitations on the scope of this invention. [0032] Example 1 illustrates the preparations of preblends of silica and fatty-acid- derivatives.

EXAMPLE 1

[0033] Preblend 1, consisting of 57.2 wt% Zeothix 265 silica powder (from J.M. Huber Corporation), 21.4 wt% oleamide (Crodamide VRX powder, from Croda Polymer Additives), and 21.4 wt% stearamide (Crodamide SR powder, from Croda Polymer Additives), was prepared in a Littleford Model W-10 Intensive Mixer apparatus by: (1) charging 1.144 Ib of the silica powder and 0.428 Ib each of the oleamide and the stearamide powders in the mixing bowl; and (2) blending this mixture for 15 minutes at 900 rpm rotor speed. The resulting material was a free-flowing powder. [0034] Preblend 2, consisting of 50 wt% Sylobloc® 47 silica powder and 50 wt% oleamide, was purchased from Grace-Davison under the trade name Sylobloc® M- 150. Although the details of the preparation of the preblend are not available, the supplier indicated that this material was prepared by blending the base silica (Sylobloc® 47 silica powder from Grace-Davison) and the oleamide raw material powder together in an intensive mixer apparatus.

[0035] Preblend 3, consisting of 50 wt% Sylobloc® 47 silica powder and 50 wt% erucamide, was purchased from Grace-Davison under the trade name Sylobloc® M-250. Although the details of the preparation of the preblend are not available, the supplier

® indicated that this material was prepared by blending the base silica (Sylobloc 47 silica powder from Grace-Davison) and the erucamide raw material powder together in an intensive mixer apparatus.

TABLE 1

[0036] Table 1 - Bulk Densities of the Preblends Versus Bulk Densities of the Base

[0037] Example 2 illustrates manufacture of additive granules containing Preblend 1.

EXAMPLE 2

[0038] The powder feed for granulation was prepared in a 1.5 cu. ft. ribbon blender (Day Corporation), which was equipped with two liquid spray nozzles that feed from a nitrogen-pressurized (to 45 psig) supply tank holding isohexane solvent. [0039] The feed blend for granulation was prepared by: (1) charging 2.40 Ib of isohexane into the supply tank; (2) charging 3.52 Ib calcium stearate powder (Baerlocher USA, Code 5700), 0.64 Ib Ethanox® 310 Antioxidant powder (Albemarle Corporation),

® 2.88 Ib Ethaphos 368 Antioxidant powder (Albemarle Corporation), and 8.96 Ib

Preblend 1 powder (of Example 1, above) into the bender; (3) blending the powders at nominally 70 rpm rotor speed for 3 minutes; (4) while continuing to blend the powders, spraying the isohexane solvent onto the powder bed in the blender; and (5) discharging the resulting feed blend into the polyethylene (PE) bags and sealing the bags. [0040] A Kahl Model 14-175 Pellet Mill (purchased from LCI Corporation) was used to manufacture the additive granules from this feed blend. This pellet mill was equipped with a die plate having holes of 3.0 mm diameter and 3.0 L:D ratio (where L is the working length and D is the diameter of the die holes) and set up to run at 125 rpm rotor speed and 7.5 mm cutter gap. A twin-screw volumetric feeder (K-Tron Model KCVKT20, equipped with auger-design screws and Digi-Drive Controller), which was positioned to discharge directly into the center of the in-take of the pellet mill, was used to feed the feed blend to be granulated.

[0041] The output of the pellet mill was collected in a series of steel pans, which were then placed in a forced-circulations, nitrogen-purged drying oven at 55⁰C for about 40 minutes to remove the isohexane solvent. The resulting material was then manually sieved (US Standard #8 sieve) to remove the unders, leaving the finished granulated product (i.e., the +8 mesh material).

[0042] The rate of granule production was calculated from the weight of finished product in the collection pan divided by the collection time. As shown in Table II, during the granulation process, the screw speed of the feeder was increased in increments in order to determine the capacity of the pellet mill (i.e., the maximum rate of production of finished granules). At the end of this granulation run (i.e., when all of the feed blend had been used up), the pellet mill had not yet reached capacity as shown by the fact that neither flooding of the pellet mill nor reaching a maximum pelleting rate had been achieved. Therefore, the pellet mill capacity for this feed blend is greater than 72 lb/hr.

TABLE 2

[0043] Table 2 - Pellet Mill Capacity Determination for the Granulation Process of Example 2

[0044] Example 3 illustrates manufacture of additive granules containing Preblend 2.

EXAMPLE 3

[0045] The powder feed for granulation was prepared in a 1.5 cu. ft. ribbon blender (Day Corporation), which was equipped with two liquid spray nozzles that feed from a nitrogen- pressurized (to 45 psig) supply tank holding isohexane solvent.

[0046] The feed blend for granulation was prepared by: (1) charging 3.75 Ib of isohexane into the supply tank; (2) charging 5.50 Ib calcium stearate powder (Baerlocher

® USA, Code 5700), 1.00 Ib Ethanox 310 Antioxidant powder (Albemarle Corporation),

4.50 Ib Ethaphos® 368 Antioxidant powder (Albemarle Corporation), and 14.00 Ib Preblend 2 powder (of Example 1, above) into the bender; (3) blending the powders at nominally 70 rpm rotor speed for 3 minutes; (4) while continuing to blend the powders, spraying the isohexane solvent onto the powder bed in the blender; and (5) discharging the resulting feed blend into the polyethylene (PE) bags and sealing the bags. [0047] As in Example 2 above, a Kahl Model 14-175 Pellet Mill (purchased from LCI Corporation) was used to manufacture the additive granules from this feed blend. This pellet mill was equipped with a die plate having holes of 3.0 mm diameter and 3.0 L: D ratio (where L is the working length and D is the diameter of the die holes) and set up to run at 125 rpm rotor speed and 7.5 mm cutter gap. A twin-screw volumetric feeder (K- Tron Model KCVKT20, equipped with auger-design screws and Digi-Drive Controller), which was positioned to discharge directly into the center of the in-take of the pellet mill, was used to feed the feed blend to be granulated.

[0048] The output of the pellet mill was collected in a series of steel pans, which were then placed in a forced-circulation, nitrogen-purged drying oven at 55⁰C for about 40 minutes to remove the isohexane solvent. The resulting material was then manually sieved (US Standard #8 sieve) to remove the unders, leaving the finished granulated product (i.e., the +8 mesh material).

[0049] The rate of granule production was calculated from the weight of finished product in the collection pan divided by the collection time. As in Example 2, during the granulation process, the screw speed of the feeder was increased in increments in order to determine the capacity of the pellet mill (i.e., the maximum rate of production of finished granules). At the end of this granulation run (i.e., when all of the feed blend had been used up), the granule production rate had reached 163 lb/hr and pellet mill had not yet reached capacity as shown by the fact that neither flooding of the pellet mill nor reaching a maximum pelleting rate had been achieved. Therefore, the pellet mill capacity for this feed blend is greater than 163 lb/hr. [0050] Example 4 illustrates manufacture of additive granules containing Preblend 3.

EXAMPLE 4

[0051] The powder feed for granulation was prepared in a 1.5 cu. ft. ribbon blender (Day Corporation), which was equipped with two liquid spray nozzles that feed from a nitrogen- pressurized (to 45 psig) supply tank holding isohexane solvent.

[0052] The feed blend for granulation was prepared by: (1) charging 3.75 Ib of isohexane into the supply tank; (2) charging 5.50 Ib calcium stearate powder (Baerlocher USA, Code 5700), 1.00 Ib Ethanox® 310 Antioxidant powder (Albemarle Corporation),

® 4.50 Ib Ethaphos 368 Antioxidant powder (Albemarle Corporation), and 14.00 Ib

Preblend 3 powder (of Example 1, above) into the bender; (3) blending the powders at nominally 70 rpm rotor speed for 3 minutes; (4) while continuing to blend the powders, spraying the isohexane solvent onto the powder bed in the blender; and (5) discharging the resulting feed blend into the polyethylene (PE) bags and sealing the bags. [0053] As in Example 3 above, a Kahl Model 14-175 Pellet Mill (purchased from LCI Corporation) was used to manufacture the additive granules from this feed blend. This pellet mill was equipped with a die plate having holes of 3.0 mm diameter and 3.0 L: D ratio (where L is the working length and D is the diameter of the die holes) and set up to run at 125 rpm rotor speed and 7.5 mm cutter gap. A twin-screw volumetric feeder (K- Tron Model KCVKT20, equipped with auger-design screws and Digi-Drive Controller), which was positioned to discharge directly into the center of the in-take of the pellet mill, was used to feed the feed blend to be granulated.

[0054] The output of the pellet mill was collected in a series of steel pans, which were then placed in a forced-circulation, nitrogen-purged drying oven at 55⁰C for about 40 minutes to remove the isohexane solvent. The resulting material was then manually sieved (US Standard #8 sieve) to remove the unders, leaving the finished granulated product (i.e., the +8 mesh material).

[0055] The rate of granule production was calculated from the weight of finished product in the collection pan divided by the collection time. As in Example 3, during the granulation process, the screw speed of the feeder was increased in increments in order to determine the capacity of the pellet mill (i.e., the maximum rate of production of finished granules). At the end of this granulation run (i.e., when all of the feed blend had been used up), the granule production rate had reached 163 lb/hr and pellet mill had not yet reached capacity as shown by the fact that neither flooding of the pellet mill nor reaching a maximum pelleting rate had been achieved. Therefore, the pellet mill capacity for this feed blend is greater than 163 lb/hr.

COMPARATIVE EXAMPLE

[0056] In order to more clearly demonstrate the improvements in granule production rates of the instant invention, granule production rates were determined using pelleting processes described previously by Dunski (U.S. Pat. No. 5,846,656, which discloses the utilization of fatty acid derivatives, but neither the utilization of a processing solvent nor the utilization of a preblend) and Semen (U.S. Pat. No. 6,821,456; U.S. Pat. No. 6,800,228; U.S. Pat. No. 6,596,198; U.S. Pat. No. 6,515,052; U.S. Pat. No. 6,126,863; U.S. Pat. No. 6,126,862; U.S. Pat. No. 6,056,898; and U.S. Pat. No. 5,846,656, which teach the advantages of using processing solvents but not of silica/fatty-acid-derivative preblends). These comparative pelleting processes were run in the same fashion as in Example 1, except with the following changes: (1) the preblending of the silica with the fatty acid amide was omitted (i.e., a mixture of the silica powder and the fatty acid amide powder, in the same proportions of the preblend, was substituted for the preblend); and/or (2) the isohexane processing solvent (and the drying step on the resulting granules) was left out of the feed blend for granulation. The comparative processes examined and the resulting pellet mill capacities obtained are shown in Table 3. Comparison of the pellet mill capacities of Table 3 with those obtained in Examples 2-4 above clearly demonstrate the vastly improved manufacturing rates obtained with the process of the instant invention.

TABLE 3

[0057] Some additional embodiments of this invention are as follows:

A) A process for manufacturing granules, the process comprising:

• combining together (i) a silica powder and (ii) a fatty component, to form a preblend;

• combining the preblend with at least one polymer additive, to form a powder blend;

• combining a processing solvent and the powder blend to form a mixture, preferably by adding a processing solvent to the powder blend to form a mixture, and more preferably by spraying a processing solvent onto the powder blend to form a mixture; and

• granulating the mixture to form the granules.

B) The process according to A), the process further comprising: removing at least a portion of the processing solvent from the granules to form dried granules.

C) The process according to B), the process further comprising: separating under-sized particles smaller than a preselected size from the dried granules to thereby produce dried granules of a pre-selected average size.

D) The process according to A), wherein the fatty component is selected from the group consisting of: a fatty acid, a fatty alcohol, a fatty acid amide, a fatty acid ester, an ester of a fatty alcohol, and a combination of two or more of the foregoing.

E) The process according to A), wherein the fatty component is introduced as either a powdered solid or a melted liquid.

F) The process according to A), wherein the polymer additive comprises at least one antioxidant component additive.

G) The process according to F), wherein the antioxidant component additive comprises a phenolic antioxidant, a phosphite antioxidant, or a combination thereof.

H) The process according to F), wherein the antioxidant component further comprises a sulfur-based antioxidant synergist. I) The process according to H), wherein the amount of the sulfur-based antioxidant synergist is in the range of from about 20 wt% to about 60 wt% of the total weight of the antioxidant component. J) The process according to A), wherein the polymer additive further comprises one or more additional additives selected from an acid neutralizer, a nucleating agent, a clarifier, a lubricant and mold-release agent, an antistat, a processing aid, a filler, or any combination of two or more of the foregoing.

K) The process according to A), wherein the amount of fatty component used to form the preblend is in the range of about 15 wt% to about 95 wt% of the preblend.

L) The process according to claim 1, wherein the aerated bulk density of the preblend is at least 25% higher than the aerated bulk density of the silica powder.

M) The process according to A), wherein the aerated bulk density of the preblend is at least 50% higher than the aerated bulk density of the silica powder.

N) The process according to A), wherein the aerated bulk density of the preblend is at least 100% higher than the aerated bulk density of the silica powder.

O) The process according to A), wherein the fatty component is either a single compound or a mixture of compounds selected from the group consisting of a fatty alcohol having from 12 to 22 carbon atoms in the molecule or an ester thereof and a fatty acid having from 12 to 22 carbon atoms in the molecule or an ester, glycerol ester, or amide of the same, where the amides of fatty acids include primary amides, secondary amides, and secondary bis-amides, in which the functional group attached to the nitrogen of the secondary amides and secondary bis-amides contain 1 to 22 carbon atoms.

P) The process according to A), wherein the amount of the processing solvent is in the range of about 3 wt% to 30 wt% of the total weight of the mixture.

Q) The process according to A), wherein the processing solvent comprises a hydrocarbon containing in the range of 3 to 7 carbon atoms in the molecule.

R) The process according to A), wherein the processing solvent is either cyclohexane or isohexane.

[0058] It is to be understood that the reactants and components referred to by chemical name or formula anywhere in this document, whether referred to in the singular or plural, are identified as they exist prior to coming into contact with another substance referred to by chemical name or chemical type (e.g., another reactant, a solvent, or etc.). It matters not what preliminary chemical changes, transformations and/or reactions, if any, take place in the resulting mixture or solution or reaction medium as such changes, transformations and/or reactions are the natural result of bringing the specified reactants and/or components together under the conditions called for pursuant to this disclosure. Thus the reactants and components are identified as ingredients to be brought together in connection with performing a desired chemical operation or reaction or in forming a mixture to be used in conducting a desired operation or reaction. Also, even though an embodiment may refer to substances, components and/or ingredients in the present tense ("is comprised of", "comprises", "is", etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, blended or mixed with one or more other substances, components and/or ingredients in accordance with the present disclosure.

[0059] Also, even though the claims may refer to substances in the present tense (e.g., "comprises", "is", etc.), the reference is to the substance as it exists at the time just before it is first contacted, blended or mixed with one or more other substances in accordance with the present disclosure.

[0060] Except as may be expressly otherwise indicated, the article "a" or "an" if and as used herein is not intended to limit, and should not be construed as limiting, the description or a claim to a single element to which the article refers. Rather, the article "a" or "an" if and as used herein is intended to cover one or more such elements, unless the text expressly indicates otherwise.

[0061] This invention is susceptible to considerable variation within the spirit and scope of the appended claims.

Claims

1. A process for manufacturing granules, the process comprising: combining together (i) a silica powder and (ii) a fatty component, to form a preblend; combining the preblend with at least one polymer additive, to form a powder blend; combining a processing solvent and the powder blend to form a mixture; and granulating the mixture to form granules.

2. A process according to claim 1 wherein the processing solvent is sprayed onto the powder blend.

3. The process according to claim 1, the process further comprising removing at least a portion of the processing solvent from the granules to form dried granules.

4. The process according to claim 3, the process further comprising separating undersized particles smaller than a preselected size from the dried granules to thereby produce dried granules of a pre-selected average size.

5. The process according to claim 1, wherein the fatty component is selected from the group consisting of: a fatty acid, a fatty alcohol, a fatty acid amide, a fatty acid ester, an ester of a fatty alcohol, and a combination of two or more of the foregoing.

6. The process according to claim 1, wherein the fatty component is introduced as either a powdered solid or a melted liquid.

7. The process according to claim 1, wherein the polymer additive further comprises one or-additional additives selected from an antioxidant, an acid neutralizer, a nucleating agent, a clarifier, a lubricant and mold-release agent, an antistatic agent, a processing aid, a filler, or any combination of two or more of the foregoing.

8. The process according to claim 1, wherein the amount of fatty component used to form the preblend is in the range of about 15 wt% to about 95 wt% of the preblend and wherein the aerated bulk density of the preblend is at least 25% higher than the aerated bulk density of the silica powder.

9. The process according to claim 1, wherein the amount of the processing solvent is in the range of about 3 wt% to 30 wt% of the total weight of the mixture.

10. The process according to claim 1, wherein the processing solvent comprises a saturated hydrocarbon containing in the range of 5 to 7 carbon atoms in the molecule.