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Process aid for melt processable polymersRelated Patent Categories: Synthetic Resins Or Natural Rubbers -- Part Of The Class 520 Series, Natural Rubber Compositions Having Nonreactive Materials (dnrm) Other Than: Carbon, Silicon Dioxide, Glass Titanium Dioxide, Water, Hydrocarbon, Halohydrocarbon, Ethylenically Unsaturated Reactant Admixed With A Preformed Reaction Product Derived From: (a) At Least One Polycarboxylic Acid, Ester, Or Anhydride; (b) At Least One Polyhydroxy Compound; And (c) At Least One Fatty Acid Glycerol Ester, Or A Fatty Acid Or Salt Derived From A Naturally Occurring Glyceride, Tall Oil, Or A Tall Oil Fatty Acid, At Least One Solid Polymer Derived From Ethylenic Reactants Only, With Saturated Si-c Or Si-h Reactant Or Polymer Thereof; Or With Solid Copolymer Derived From At Least One Si-c Or Si-h Reactant Wherein At Least One Of The Reactants Forming The Solid Copolymer Is Saturated; Or With Spfi Wherein At Least One Of The Necessary Ingredients Contains A Si-c Or Si-h Bond Or With A Reaction Product Thereof; Or With A Sicp Containing A Si-h Or Si-c Bond, Contacting With Nonsilicon-containing Sicp, Nonsilicon-containing Spfi, Or Polymer Thereof; Or With Two Or More Solid PolymersProcess aid for melt processable polymers description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070244257, Process aid for melt processable polymers. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 11/294,796, filed Dec. 6, 2005, which is a division of U.S. application Ser. No. 10/364,040, filed Feb. 11, 2003, now U.S. Pat. No. 7,001,951 B2, which is a continuation of U.S. application Ser. No. 09/953,638, filed Sep. 17, 2001, now U.S. Pat. No. 6,642,310 B2, and claims the benefit of U.S. Provisional Application No. 60/269,247, filed Feb. 16, 2001. FIELD OF THE INVENTION [0002] The present invention relates to extrusion of non-fluorinated melt-processable polymers which contain fluoropolymer processing aids. BACKGROUND OF THE INVENTION [0003] The melt extrusion of high molecular weight polymers, for example, hydrocarbon polymers and polyamides, into shaped structures such as tubing, pipe, wire coating or film is accomplished by well-known procedures wherein a rotating screw pushes a viscous polymer melt through an extruder barrel into a die in which the polymer is shaped to the desired form and is then subsequently cooled and solidified into a product having the general shape of the die. [0004] In order to achieve low production costs, it is desirable to extrude the polymer at rapid rates. Higher extrusion rates may be readily obtained by increasing the rate of revolution of the extruder screw. However, this technique is subject to limitations imposed by the viscoelastic properties of the polymer substrate. Thus, at very high extrusion rates an unacceptable amount of thermal decomposition of the polymer can result. Further, extrudates having a rough surface are often obtained which can lead to formation of an undesirable pattern on the surface of the extrudate. These surface defects are also known as melt fracture. Extrusion at elevated temperatures obviates this problem but adds to processing costs. Also, cooling of the extrudate becomes problematic. In addition, if polyolefins are extruded at temperatures near their decomposition points, polymer degradation occurs. [0005] It is desirable, therefore, to find highly efficient means of increasing the extrusion rate without raising the melt temperature, while producing articles having smooth surfaces. Changes in extruder and die configuration can improve polymer melt flow, but these modifications are not always practical or economically feasible. Another approach involves the addition of conventional wax-type process aids which reduce bulk viscosity and in some cases improve processing properties. However, the efficiency is marginal and the high levels of additive required often adversely affect other properties. [0006] In Blatz, U.S. Pat. No. 3,125,547, it is disclosed that the use of 0.01-2.0 wt. % of a fluorocarbon polymer that is in a fluid state at the processing temperature (e.g. a fluoroelastomer) will reduce die pressure in extrusions of both high and low density polyethylenes, as well as other polyolefins. Further, use of this additive allows significant increase in extrusion rates without melt fracture. [0007] Kamiya and Inui, in Japanese Examined Patent Application Kokoku 45-30574, cite the use of crystalline fluorocarbon polymers at temperatures below their melting points to eliminate die build-up, but they disclose nothing regarding other extrusion improvements. [0008] Nishida, et al., in Japanese Patent Application Publication Kokai 62-64847, disclose injection molding compositions comprising a mixture of a) an ethylene/alpha olefin copolymer having a melt flow rate (MFR) of 0.2-200 g/10 minutes and a density of 0.850-0.945 g/cm.sup.3, with b) 0.001-1% by weight of a fluorinated hydrocarbon polymer having a fluorine to carbon ratio of at least 1:2. [0009] Chu, in U.S. Pat. No. 4,740,341, discloses blends having improved extrudability comprising linear polymers of ethylene having incorporated therein small amounts of fluorocarbon polymers and polysiloxanes. The fluorocarbon polymers have fluorine to carbon ratios of at least 1:2 and are fluid at 120.degree.-300.degree. C. [0010] Larsen, in U.S. Pat. No. 3,334,157, discloses polyethylene which has been modified to improve its optical properties by incorporation of 0.015 to greater than 1.7% by wt., based on the mixture, of finely divided polytetrafluoroethylene. [0011] More recently, improved fluoropolymer process aid compositions have been disclosed in for example, U.S. Pat. Nos. 4,855,360; 5,587,429 and 5,707,569. In these fluoropolymer process aid compositions, a second additive, such as a poly(oxyalkylene) or an ionomer resin, is introduced in order to improve extrusion processability of the non-fluorinated polymer. [0012] In order to maximize processability improvements, the prior art has stated that it is desirable that the fluoropolymer process aid compositions be well dispersed in the non-fluorinated polymer which is to be extruded and that the smaller the particle size of the fluoropolymer, the better the dispersion and thus the better the processability. See, for example, "Dynamar.TM. Polymer Processing Additive Optical Microscopy Method for Dispersion Analysis in Polyolefins" (Dyneon 1997), which recommends uniform dispersions and fluoropolymer process aid particle sizes 2 microns or less in the extrudate; "Dynamar.TM. Polymer Processing Additives Direct Addition During Resin Manufacture" (Dyneon 12/2000), which recommends uniform dispersions and fluoropolymer process aid particle sizes of 3 microns or less in the extrudable composition. Similar recommendations have been made in U.S. Pat. Nos. 3,125,547; 5,010,130; and 6,048,939. [0013] Due to these references which teach that extrusion processability is improved by improving the degree of the dispersion of the fluoropolymer process aid in the melt processable polymer, and by decreasing the particle size of the fluoropolymer, much of the prior work in this field has focused on improving the quality of the dispersion and minimizing the fluoropolymer particle size. Still, there is room for improvement in extrusion processability. SUMMARY OF THE INVENTION [0014] It has been surprisingly discovered that extrudable compositions which contain predominantly large particle size fluoropolymer actually process better, exhibiting fewer melt defects and have faster conditioning times, than those compositions which follow the recommendations of the prior art and strive for maximum fluoropolymer dispersion. By "predominantly large particle size fluoropolymer" is meant a weight average particle size (as hereinafter defined) of greater than 2 microns, but less than 10 microns, as measured at a point immediately preceding the die. Extrudable compositions which contain predominantly large particle size fluoropolymer can be achieved by a number of means. [0015] Accordingly, one aspect of the present invention is an extrudable composition for passing through a die, said composition comprising: [0016] A) a non-fluorinated melt processable polymer; and [0017] B) 25 to 2000 parts per million by weight, based on total weight of the extrudable composition, of fluoropolymer, said fluoropolymer having a weight average particle size greater than 2 microns and less than 10 microns, as measured at a point immediately preceding the die; and wherein said composition is substantially free of interfacial agent. [0018] Another aspect of the present invention is an extrudable composition for-passing through a die, said composition comprising: [0019] A) a non-fluorinated melt processable polymer; [0020] B) 25 to 2000 parts per million by weight, based on total weight of the extrudable composition, of a fluoropolymer, said fluoropolymer having a weight average particle size greater than 2 microns and less than 10 microns, as measured at a point immediately preceding the die; and [0021] C) at least an effective amount of interfacial agent to achieve a fluoropolymer weight average particle size greater than 2 microns and less than 10 microns, as measured at a point immediately preceding the die, but no more than a 5:1 weight ratio of interfacial agent to fluoropolymer. [0022] Another aspect of the instant invention is a process aid masterbatch comprising: [0023] A) a non-fluorinated melt processable polymer; [0024] B) 1 to 50 weight percent, based on total weight of the masterbatch, of fluoropolymer; and [0025] C) at least an effective amount, to improve processability, of interfacial agent, but no more than a 5:1 weight ratio of interfacial agent to fluoropolymer, with the proviso that if the interfacial agent is a poly(oxyalkylene) polymer, it is present at less than a 1:1 weight ratio of poly(oxyalkylene) polymer to fluoropolymer. DETAILED DESCRIPTION OF THE INVENTION [0026] The present invention is directed to means for improving the extrusion processability of non-fluorinated melt processable polymer compositions which contain fluoropolymer as a process aid. The term "extrusion processability" as used herein refers to the conditioning time (i.e. the elapsed time after extruder start up in which extruded articles exhibit a high degree of melt fracture before obtaining an extrudate having a smooth surface, free of melt fracture). Obviously, in order to minimize waste and reduce costs, a very short conditioning time is desirable. [0027] Examples of non-fluorinated melt processable polymers include, but are not limited to, hydrocarbon resins, polyamides, chlorinated polyethylene, polyvinyl chloride, and polyesters. By the term "non-fluorinated" it is meant that the ratio of fluorine atoms to carbon atoms present in the polymer is less than 1:1. The non-fluorinated melt-processable polymers of this invention may be selected from a variety of polymer types. Such polymers include hydrocarbon polymers having melt indexes (measured according to ASTM D1238 at 190.degree. C., using a 2160 g weight) of 5.0 g/10 minutes or less, preferably 2.0 g/10 minutes or less. The hydrocarbon polymers may be elastomeric copolymers of ethylene, propylene, and optionally a non-conjugated diene monomer, for example 1,4-hexadiene. In general, hydrocarbon polymers also include any thermoplastic hydrocarbon polymer obtained by the homopolymerization or copolymerization of a monoolefin of the formula CH.sub.2=CHR, where R is H or an alkyl radical, usually of not more than eight carbon atoms. In particular, this invention is applicable to polyethylene, of both high density and low density, for example, polyethylenes having a density within the range 0.85 to 0.97 g/cm.sup.3; polypropylene; polybutene-1; poly(3-methylbutene); poly(methylpentene); and copolymers of ethylene and alpha-olefins such as propylene, butene-1, hexene-1, octene-1, decene-1, and octadecene. Hydrocarbon polymers may also include vinyl aromatic polymers such as polystyrene. Because specific hydrocarbon polymers exhibit differing melt characteristics, the practice of this invention may have greater utility in some hydrocarbon polymers than in others. Thus, hydrocarbon polymers such as polypropylene and branched polyethylene that are not of high molecular weight have favorable melt flow characteristics even at lower temperatures, so that surface roughness and other surface defects can be avoided by adjustment of extrusion conditions. These hydrocarbon polymers may only require the use of the fluorocarbon polymer extrusion aids and process of this invention under unusual and exacting extrusion conditions. However, other polymers such as high molecular weight, high density polyethylene, linear low density polyethylene copolymers, high molecular weight polypropylene, and propylene copolymers with other olefins, particularly those with narrow molecular weight distributions, do not permit this degree of freedom in variation of extrusion conditions. It is particularly with these resins that improvements in the surface quality of the extruded product are obtained with the compositions and process of this invention. Continue reading about Process aid for melt processable polymers... Full patent description for Process aid for melt processable polymers Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Process aid for melt processable polymers patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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