EP0820485A1

EP0820485A1 - Improved processability of metallocene-catalyzed polyolefins

Info

Publication number: EP0820485A1
Application number: EP96911725A
Authority: EP
Inventors: Dirk Jozef Michiels
Original assignee: Exxon Chemical Patents Inc
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 1995-04-13
Filing date: 1996-04-10
Publication date: 1998-01-28
Also published as: WO1996032441A1; AU5481796A

Abstract

Metallocene-catalyzed polyolefins exhibit a tendency to increase motor loads and torque when extruded, due to their relative shear insensitivity. The use of a solid solvent combined with the linear polyolefin can reduce motor loads and torque to improve processability. The solid solvent chosen should leave the physical properties of an extrusion fabricated article substantially unaltered when compared to the properties of the linear polyolefin itself. The linear polyolefin will have a Mw/Mn less than 2.8. The solid solvent will have: a disassociation temperature (Tdi) below the processing temperature of the combination of linear polyolefin and solid solvent, an association temperature (Ta) above the crystallization temperature of the linear polyolefin; a solubility index from 15 to 20 MPa?1/2, a M¿n from 250 to 5000; an extractibility (in combination with the polyolefin) in n-hexane at 50 °C below 5.5 weight percent for the total blend, a degradation temperature in excess of 300 °C, and a refractive index within ± 10% of the refractive index of the linear polyolefin.

Description

TITLE: Improved Processability of Metallocene-Catalyzed Polyolefins

TECHNICAL FIELD

This invention relates generally to materials added to metallocene-catalyzed narrow molecular weight polyolefin polymers made with metallocene catalyst systems to improve their melt processing properties. More specifically, this invention relates to solid solvents to improve the melt processability of metallocene-catalyzed polyolefins and polyolefin blends containing one or more metallocene-catalyzed polyolefins, while physical properties of articles fabricated with these polyolefins and solvents are substantially the same as those of articles fabricated from the linear polyolefin itself.

BACKGROUND

Advances in polymer synthesis technology have often brought with them changes in processing of the polymers subsequent to polymerization. For example, when a low pressure gas-phase or solution reactor produced, traditional Ziegler-Natta catalyzed, linear low density polyethylene (LLDPE) process was widely commercialized in the late 1970's and 1980's, substantially all such polymers produced were less shear sensitive in the melt phase than, for instance, free radical polymerized polyolefins, the latter having been widely used prior to the LLDPE introduction. The LLDPE polymer's higher melt viscosity at typical processing conditions made the then existing extrusion and molding equipment less efficient as a polymer pumping apparatus, for instance as measured by pounds per hour per inch of die (lb./hr/in of die) (kg/hr/cm of die) when used to process linear low density Ziegler-Natta catalyzed polyolefin polymers.

The introduction of metallocene-catalyzed linear polymers has, in certain instances, once again brought similar melt processing difficulties, probably due at least in part to the comparatively narrow molecular weight distribution and narrow composition distribution of these metallocene-catalyzed materials when compared for example to traditional Ziegler-Natta catalyzed polyolefin polymers, solution polymerized mono-cyclopentadienyl catalyzed polyolefins, or especially to free radical initiated polyolefins. Due to the newness of the metallocene-catalyzed polyolefin polymers and their relatively low current commercial volume of sales, fabricators and converters of polyolefin polymers have not been compelled to push the processing envelope of these polymers. As metallocene-catalyzed polyolefin polymers reach commercially significant sales and use, their relative difficulty of processing of certain of these metallocene-catalyzed polymers will become more important as converters of these resins attempt to maximize the output on a given machine while using these new polymers. Polyolefins (hereinafter "metallocene-catalyzed polyolefins") made from metallocene based catalyst systems (which include mono-cyclopentadienyl and bis(cyclopentadienyl) metallocene catalyst systems as described in U.S. Patents 5,026,798 and 5,324,800 incorporated herein by reference for purposes of U.S. patent practice) generally display a narrow molecular weight distribution (MWD) (M_^/M.,) generally less than 4, preferably less than 3. These polymers show remarkably improved physical properties compared with, for instance, traditional Ziegler-Natta catalyzed polyolefin polymers, due in part to their relatively narrow compostion distribution and narrow molecular weight distribution. However, in certain instances, particularly with polyolefins prepared from bis(cyclopentadienyl) catalyst systems, their narrow molecular weight distribution also gives them a generally higher viscosity at melt processing temperatures, that is generally higher than that of mono- cyclopentadienyl catalyzed polymers, traditional Ziegler-Natta catalyzed linear polymers, or free radical polymerized polyolefins. This viscosity difference, combined with a lower melt phase shear sensitivity of these metallocene-catalyzed polymers than certain other metallocene, traditional Ziegler-Natta catalyzed polyolefin polymers and free radical polymerized polyolefins, leads to more difficult melt phase processing or in other words, higher motor loads, higher extruder back-pressures, and potentially lower maximum specific output. Such higher torque and motor loads mean that often a given extruder's output may be lowered because the energy or horsepower of the extruder may not be sufficient to pump as much of a more viscous polymer. Alternatively, more energy may be used to pump the same amount of polymer (at a constant output based on weight/unit of die circumference/unit of time) if the machine is not power limited. In the past there have been numerous attempts, many of them successful, to improve the processability of various kinds of polymers. These attempts have included adding lubricants, or plasticizers, use of other viscosity reduction techniques, and other methods of improving processing. However, along with improving melt processability, many of these solutions have had deleterious effects on other important aspects of polymer melt processing, fabrication, and fabricated articles made from these polymers. Some examples of such detrimental effects include that the materials intended to improve processability tend to reduce physical properties, and that others have drawbacks such as increasing solvent extractables (limited for food law compliance). Others have an unacceptable level of volatility causing unacceptable smoking or plate- out in melt processing operations. Another problem common to many previous solutions was that while lowering power requirements, motor load and or torque, output decreased, as measured by the specific output (kg/hr/cm of die). To improve polymer melt phase processability, some solutions have been offered. Chung in the Journal of Applied Polymer Science suggests the concept of a solid solvent utilizing a low molecular weight crystalline material (LMC) as a processing aid. A LMC is purported to become a solvent for the polymer at high processing temperatures reducing the melt viscosity and thus enhancing processability, but to become a non-solvent for the polymer at low use temperature precipitating out of the polymer without adversely affecting the properties. This document suggests using acetanilide as a solid solvent for polystyrene and two ABA-type block copolymers containing polystyrene end blocks.

EP 0 279 573 A2 suggests that the melt viscosity of vinylidene chloride polymers is purportedly reduced by introducing a solid solvent such as dimethyl sulfone into the polymer. The sulfone may be compatible with vinylidene chloride polymers at a processing temperature above the solid solvent melting point and will reduce the melt viscosity and improve processing of the vinylidene chloride polymer. Upon cooling below the solid solvent melting point, the solid solvent is said to become micro dispersed in the vinylidene chloride polymer with little or no solid solvent remaining dissolved in the vinylidene chloride polymer.

EP 0 324 264 A2 suggests that the extrudability of linear polymers of ethylene such as low density copolymers of ethylene of a C4 to CIO olefins (LLDPE) into thin films is improved by adding small amounts, for example, of 0.02 to 2 weight percent ethylene vinyl polymer to reduce melt fracture, head pressure and to obtain having excellent anti-blocking characteristics. Optionally, diatomaceous earth is added to further reduce blocking.

EP 0 308 090 A2 suggests that head pressure and extruder torque in the extrusion of linear ethylene polymers such as linear low density polyethylene (LLDPE) are reduced by adding a small amount (less than 3 weight percent) of a thermoplastic polyamide polymer. Films extruded from the blend purportedly exhibit better surface appearance by reduction of melt fracture.

EP 0 308 089 A2 suggests that head pressure and extruder torque in the extrusion of linear ethylene polymers such as linear low density polyethylene (LLDPE) are purportedly reduced by adding a small amount (less than 5 weight percent) of a thermoplastic polyurethane. Films extruded from the blend are said to exhibit better surface appearance by reduction of melt fracture.

There is a commercial a need therefore for a material that may generally lower extrusion power requirements, lower extruder back pressure, improve the melt processability of metallocene-catalyzed polymers on a specific output basis, and may have a substantially neutral or improvement effect on most fabricated article physical properties.

SUMMARY I have discovered that combining metallocene-catalyzed polyolefins with a solid solvent can provide advantages in melt processing of metallocene-catalyzed polyolefins. The advantages include, but are not limited to; lower extruder torque, lower extruder back-pressures, lower power requirements and/or improved maximum outputs at substantially the same specific extruder output, and with generally little smoking and/or plate-out. Additionally, these advantages can be realized generally without loss of physical properties of an article fabricated from the combination. I have thus found that the above discussed disadvantages associated with metallocene- catalyzed polyolefins can generally be solved by the material combinations of various embodiments of my invention. When a solid solvent is used in a metallocene-catalyzed polyolefin, the result is a combination which has a polyolefin or polyolefins (majority component) selected from a group consisting of polyethylene, polypropylene, ethylene homopolymers, ethylene-alpha-olefin copolymers, ethylene alpha-olefin terpolymers, propylene homopolymers, propylene-ethylene copolymers, propylene-alpha-olefin copolymers or terpolymers and mixtures (combinations) and blends thereof, where the polyolefin is made from the group of catalysts or initiators consisting of a metallocene or single site catalyzed polymerization products, a traditional Ziegler-Natta catalyzed system, and a Chromium based catalyst system. However, the majority component can also contain an additional polymer or polymers. The majority component has a density in the range of from 0.85 to 0.97 g/cc preferably in the range of from 0.86 to 0.96 g/cc.

The combination may also include in the range of 0.5 to 10 parts per hundred parts of the majority component, generally a metallocene-catalyzed polyolefin. As referred to in the present application, solid solvent means a material which is dispersed in the polymer in an associated state (crystal, micel, or cluster, for example) at temperatures below the processing temperature of the polymer. The solid solvent may dissociate somewhat below the (melt) processing temperature of the majority component and should have sufficiently low molecular weight to enhance extrudability, but sufficiently high molecular weight to prevent substantial screw slippage (in an extruder), smoking, or fuming during melt processing, solvent extractability (food law compliance), and plate-out. The solid solvent should preferably reassociate during or somewhat before solidification of a fabricated article based on the combination, to form a separate phase within the polymer article.

The minority or solid solvent component has: (a) a disassociation temperature (T_Λ) at or below the processing temperature of the blend; (b) an association temperature (T equal to or above the crystallization temperature of the polyolefin; (c) a solubility index in the range of from 15 to 20 (MPa) ; (d) optionally a degree of crystallinity exceeding 80%; (e) a viscosity not exceeding 2000 MPa at 170°C; (f) an extractability in n-hexane at 50°C not exceeding 5.5 weight percent based on the total weight of the combination with the majority component; (g) a degradation temperature in excess of 250°C; and (h) a refractive index within ±10% of the polyolefin majority component.

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Introduction

One embodiment of the present invention is directed to a combination of a polyolefin and a solid solvent, as well as articles fabricated based on this combination. These polyolefin compositions have improved melt processability properties which make them unique and particularly well suited for use in most melt processing operations used for fabrication of metallocene-catalyzed polyolefins.

Following is a detailed description of certain preferred metallocene-catalyzed polyolefins and solid solvents within the scope of various embodiments of my invention, preferred methods of combining the polyolefins and solid solvents, and preferred applications of these combinations. Those skilled in the art will appreciate that numerous modifications to these preferred embodiments can be made without departing from the scope of the invention. For example, while the properties of the combinations are exemplified in films and film extruders with which they are made, the combination will find use in numerous other fabricated articles. To the extent that this description is specific, this is solely for the purpose of illustrating preferred embodiments, and should not be taken as limiting. The ability to improve the melt processability of such metallocene-catalyzed polyolefins without generally negatively affecting the physical properties of fabricated articles, has been heretofore unobtainable.

The metallocene-catalyzed polyolefin/solid solvent combinations of various embodiments of the present invention will contain at least these two components. Such combinations can be achieved by schemes including but not limited to, melt compounding, dry blending, or other schemes which will be well known to those of ordinary skill in the art.

The use of headings in the application are intended to aid the reader and no other significance or limitation is intended.

The Majority Component

The majority component of the combination of the present invention is generally a melt processable polymer or polymer blend selected from the group consisting of: polyethylene, polypropylene, copolymers and teφolymers of ethylene and propylene, ethylene propylene rubber, ethylene propylene diene monomer rubber (EPDM), styrene isoprene styrene, styrene butadiene styrene, and combinations thereof. These polymers are becoming available commercially and may be prepared or polymerized by metallocene and or single site catalyst systems, however other constituents of the "majority" component may be polyolefins catalyzed or initiated with other types of catalysts or initiators or other types of catalyst mixtures. Examples of free radical, high pressure polyethylenes and ethylene copolymers include but are not limited to homopolymer polyethylene, ethylene vinyl acetate, ethylene ethyl acrylate, ethylene methyl acrylate, ethylene n-butyl acrylate, ethylene acrylic acid, ethylene methacrylic acid, ionomers of the acid co or teφolymers, combinations thereof and the like.

The majority component polyolefin may be an ethylene homopolymer or an ethylene-alpha-olefin copolymer where the polymer contains one or more alpha-olefins. The alpha-olefins will have from 3 to 20 carbon atoms. The polyolefin may also be a polypropylene, either a homopolymer polypropylene or a copolymer or teφolymer of propylene and ethylene and/or an alpha-olefin having 4 to 20 carbon atoms. The preferred alpha-olefins in either the polyethylene or the polypropylene copolymers or teφolymers, are olefins having 4 to 8 carbon atoms. Non-limiting examples of these alpha-olefins are butene-1, 4-methyl pentene-1, hexene-1, and octene-1. The use of teφolymers and tetrapolymers of the ethylene or propylene using alpha-olefins are also contemplated, as are blends of the polyolefin with other polyolefin copolymers or other thermoplastics.

While I anticipate that the primary benefit, or the most pronounced effect of the solid solvent on processability, will be evidenced with bis(cyclopentadienyl) metallocene-catalyzed polyolefins, the effect of these solid solvents will also be discernible in traditional Ziegler-Natta catalyzed, chromium catalyzed polyolefins, free radical initiated polyolefins, mono-cyclopentadienyl metallocene-catalyzed polyolefins and combinations thereof, as well, albeit, to a generally lesser degree. The majority component polyolefins may be produced in a gas phase fluidized bed reactor, stirred bed reactors, solution reactor, slurry or bulk reactors of the tank or loop type.

The use or inclusion into either the majority component, or for instance into the article fabricated from the combination of majority components and solid solvent include additives, such as for instance antioxidants, acid neutralizers, antiozonants, UV inhibitors or absorbers, colors, fillers, combinations thereof and the like are also contemplated.

Ethylene Polymers

When the polyolefin is a copolymer or teφolymer of ethylene and an alpha- olefin, the alpha-olefin or alpha-olefins are present in the ethylene copolymer in the range of from 0.2 to 20 mole percent based on the total moles of copolymer, preferably in the range of from 0.5 to 15 mole percent, more preferably in the range of from 1 to 10 mole percent. The melt index of the ethylene copolymers will be in the range of from 0.01 dg/min to 100 dg/min, preferably in the range of from 0.25 to 10 dg/min, more preferably 0.5 dg/min to 10 dg min (as measured by ASTM D 1238 condition E 190° C 2.16 kg). The density of the polymers is in the range of from 0.85 to 0.96 g cc, preferably in the range of from 0.89 to 0.93 g cc. The choice of a specific density and melt index will be driven mainly by the end use article property requirements. The molecular weight distribution of the ethylene-alpha-olefin copolymers will generally be below 2.8 (M_^ M preferably below 2.5. The composition breadth distribution index (CDBI) of the ethylene-alpha-olefin copolymer is greater than 50%, preferably more than 65. A description of methods of determining both CDBI may be found in copending application USSN 08/230,661 which is incoφorated herein by reference for purposes of US patent practice. Propylene Polymers

The propylene polymers contemplated are also catalyzed by metallocene based catalysts systems. These polymers may be propylene homopolymers or propylene or copolymers or teφolymers. A propylene copolymer, teφolymer, or tetrapolymer may also be propylene where the monomers may be selected from the group consisting of ethylene and/or alpha-olefins where the alpha-olefins have a carbon number in the range of 4 to 20, more preferably the carbon number is from 4 to 10, most preferably from 4 to 8. Comonomer or comonomers will be present in the copolymer in the range of from 0.2 to 8 mole percent based on the total mole of the copolymer, preferably from 0.5 to 6 mole percent, more preferably from 1 to 3 mole percent. The melt flow rate of any of these propylene polymers will be in the range of from 0.1 to 5000 g/10 min. (as measured by ASTM D-1238 Condition L (230°C/2.6 Kg)).

If the propylene copolymer is intended for use in a film or sheeting application, the melt flow rate is more preferably in the range of from 0.5 to 10 g/10 min. If the end use or the melt process used to convert the propylene polymer resin into a useful fabricated article is fiber spinning or extrusion, the melt flow rate is preferably in the range of from 10 to 3000 g/10 min, more preferably in the range of from 100 to 1500 g 10 min. The composition distribution of the propylene copolymers is generally narrow. The molecular weight distribution of the propylene copolymers demonstrated by the Mw Mn is in the range of up to 2.8, preferably up to 2.5, and most preferably to 2.

Solid Solvents

The solid solvents contemplated by the present invention include a broad range of materials that can most generally be described as those materials whose molecules disassociate in the melt, where the solid solvent will act as a viscosity modifier, but then will reassociate (through crystallization, micel formation, ionic bonding and the like) before or simultaneously with the recrystallization of the majority component polyolefin. The solid solvent will have a disassociation temperature ( _&) less than the normal processing temperature or melt processing temperature of the majority component, preferably more than 10° C below the melt processing temperature, more preferably more than 20° C below the melt processing temperature.

The association temperature (T of the solid solvent will be equal to or greater than crystallization temperature of the majority component, preferably 10° C greater than the crystallization temperature, preferably 20° C greater than the crystallization temperature. It will be understood by those of ordinary skill in the art that regardless of the crystallization temperature of the majority component, the crystallization temperature of the solid solvent will preferably be at or above the crystallization temperature of the majority component polyolefin. The T_a and the T_Λ can be measured utilizing techniques well known to those of ordinary skill in the art, such as Dynamic Mechanical Thermal Analysis (DMT A), differential scanning calorimeter (DSC), or hot stage microscopy.

If the solid solvent is generally non-crystalline in nature, before or simultaneously with the crystallization temperature of the majority component, the solid solvent will reassociate with the majority component. Likewise the material will disassociate at a temperature of less than the typical processing temperatures for the majority component polyolefin.

In general the solid solvent (either crystalline, non-crystalline or partially crystalline) selected will act as a viscosity modifier in the melt phase of the majority component polyolefin and will be disassociated from the polyolefin. On the other hand, after the solid solvent has reassociated and the majority component has crystallized, the solid solvent will be sufficiently reassociated with the majority component that the extractability of the combination of solid solvent, majority component, and additives will not be greater than 5.5 weight percent, preferably less than 4 weight percent, more preferably less than 3 weight percent, most preferably less than 2.6 weight percent(of the total combination) in n-hexane, as measured by a standard test of the US Food and Drug Administration noted 21 CFR § 177.1520.

Additionally, the solid solvent should reassociate with the majority component such that the physical properties of an article made from the combination should not have substantially lower values than that of the majority component without the solid solvent added.

Solid Solvents may be selected from the group consisting of C20 to C70 hydrocarbons, monofunctional C20 to C70 hydrocarbons, and multifunctional C20 to C70 hydrocarbons, wherein said functionality is selected from the group consisting of alcohols, acids, esters, sulfonates, aldehydes, ketones, ethers acid amides, amines and combinations thereof. Additionally, the solid solvent should have a number average molecular weight in the range of from 250 to 5000. Non-limiting examples of such solid solvent materials are shown below in table I. Each of the materials are available from at least one commercial source, and one of those sources is indicated in the table. Additionally Chemical Abstracts numbers (CAS#), are included for clarity. TABLE 1

Key for Table 1 :

Companv Code Companv Name

AUS AccuStandard Inc.

CILUS Cambridge Isotope Labs

CSIUS Chem Service Inc.

HMK Witco Coφ.

JNSBE Janssen Chimica

KNG King's Laboratory, Inc.

KNKUS K & K Labs

MPR Molecular Probes Inc.

PEN Penta Manufacturing Co.

PNB Pfaltz & Bauer Inc.

POL Polyester Coφ.

SHX Witco Coφ.

TCI T. C. I. America Inc.

UNC Unichema North America

The solubility index (p) of the solid solvent [Polymer Handbook - J. Brandrup/E. H. Immergut (Wiley Interscience Publications, 1989, pg. VII - 519 to pg. Vπ-559)] should be 16.5 MPa , preferably in the range of from 15 to 20, more preferably in the range of from 15 to 19.5 MPa . It will be understood that the solubility index is a measure of compatibility with the polyolefin material.

The degradation temperature or T_d of the solid solvent should be greater than 250° C, preferably greater than 275° C and more preferably greater than 300° C. It will be well understood by those of ordinary skill in the art that the degradation temperature of the solid solvent should be chosen such that degradation during normal extrusion conditions of the majority component polyolefin be avoided. To determine a satisfactory degradation temperature limit for a solid solvent, weight loss may be kept below 2.5 weight percent, preferably below 1.5, more preferably below 1 weight percent. Such weight loss may be determined by for instance Thermo-Gravimetric Analysis (TGA).

The refractive index of the polyolefin/solid solvent combination should be as close as possible to the refractive index of the majority component polyolefin preferably in the range of ± 10% of the refractive index of the majority component, where the clarity of the end product of the melt processable polyolefin is of importance.

The volatility of the solids solvent should be minimal. Those of ordinary skill in the art will appreciate that the volatility should be kept at or below the level of volatility, at normal processing temperatures, of the majority component melt processable polyolefin to avoid smoking, die build-up, and buildup on other parts around the die and extrusion zone.

Where required, the solid solvent should preferably be food law compliant.

Melt processes contemplated

Extrusion and molding are two broad categories of melt processing that take in substantially all of the shear and heat conversion processes encountered by polyethylenes or polypropylenes. Extruded products can be made into films having a thickness in the range of from 5 microns to 200 microns or a sheet having a thickness in the range of from 200 micron to 4000 microns, or fibers having a broad range of fiber deniers. In the case of films, the films may be blown films or cast films. These processes will be known to those of ordinary skill in the art. Also contemplated are extrusion blow molding and injection molding melt processing techniques.

Polyolefin Uses

Uses for polyolefin/solid solvent melt processable blends include: blown and cast films, oriented films, fibers (melt blown and spun bonded), fabrics made from said fibers, sheets and molded articles (injection molding, compression molding, extrusion blow molding, and extrusion stretch blow molding). Such extruded materials find use in trash bags, can liners, t-shirt bags, stretch films, heavy duty shipping sacks, retail bags, meat, cheese and produce packaging, snack foods packaging, food containers, diaper back sheets, diaper liners, diaper fillers, medical drapes and gowns, medical devices (e.g. syringes, IV tubing, and the like ), bottles, and pails.

Examples Example 1

An ethylene butene copolymer (EXACT® 3028, available from Exxon Chemical Company) made utilizing a metallocene catalyst is blown into a mono-layer film on a in the blown film application on a 2.5 in (64 mm) Egan extruder (24: 1 L:D) with a 60 mil (1.5 mm) die gap. The same resin was used for all three Samples. The gauge of the film made from the polymer is 1.25 mils (31.75 microns). The butene copolymer has a density of approximately 0.90 g cc and a melt index of a nominal 1.2 dg min. Sample 1 (control) is Exact 3028 extruded without additives, save for anti- oxidants, acid neutralizers, and the like, and Viton® A to substantially eliminate melt fracture. In runs 2 and 3, respectively the additives included are 500 ppm Viton® A. (Viton A can be obtained from E. I. DuPont and is one of a family of fluoroelastomers) Such fluoroelastomers are generally useful as processing aids that generally act to eliminate melt fracture.

Sample 2 has 500 ppm Viton A, and 4 weight percent of a solid solvent, a low molecular weight polypropylene wax PP 230, (available from Hoechst Celanese). Sample 3 has 500 ppm Viton A and 7.5 weight percent of LD-200.48 (a nominal 8 dg min melt index free radical initiated low density polyethylene material with 0.917 g/cc density from Exxon Chemical Company). Sample 3 represents previously suggested materials (highly branched LDPE) to improve processability. As can be seen from Table II, the control (Sample 1) exhibited a motor load

(KVA) of 12.6 compared to 10.2 and 12.4 KVA respectively for Samples 2 and 3.

Back pressure was 24.4 MPa for Sample 1, versus 21, and 23.1 MPa respectively for samples 2 and 3.

The Table II data would indicate that the additives of samples 2 and 3 improved processability to varying degrees. However, Sample 2 showed substantially more improvement than either Sample 1 or 3 in all the above comparisions.

In reviewing the film property data Table III referring to the same sets of samples, inventive Sample 2 shows dramatic property improvements in Elmendorf tear, puncture force, and puncture energy when compared to Sample 1. Specifically over 18% improvement in both MD and TD tear values over the reference (Sample 1).

While in puncture force the inventive Sample 2 is over 23% greater than Sample 1, and in puncture energy the improvement of Sample 2 is greater than 50% over Sample 1 (control).

Example 2

A blend of propylene-ethylene and propylene-hexene copolymers are extruded into a film. The motor load in KVA for the two controls (propylene-ethylene and propylene-hexene copolymers) when compared to those of the same additives as added in Example 1 are diminished at least by 10%. The same order of magnitude reduction is seen in back pressure.

Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. For example, other melt processing methods are contemplated such as for example, compounding and molding. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein. TABLE π

Sample 1 Sample 2 Sample 3 REFER EXACT

GRADE UNITS 3028 +4%PP230 +7.5%LD200

COMONOMER BUTENE BUTENE BUTENE DENSITY G/CC 0.9 0.9 0.902 MELT INDEX G/10' 1.2

MOTOR LOAD @ 65 RPM AMPS 44.5 36.2 44 KVA 12.6 10.2 12.4

BACK PRESSURE MPa 24.4 21.0 23.1

*FLH m 0.76 0.69 0.76

MELT TEMPERATURE degC 209 207 207

MOTOR LOAD (AMPS) % OF REF 100 81.3 98.9 BACK PRESSURE % OF REF 100 86.1 94.8

BUBBLE STABILITY MPM 42.7 42.7 54.9

•FLH = frost line height

TABLE in

BLOWN FILM PROPERTIES (2.5" EGAN / 60 mil DIE GAP)

Sample 1 Sample 2 Sample 3 REFER. EXACT

GRADE UNITS 3028 +4%PP230 +7.5% LD200

COMONOMER BUTENE BUTENE BUTENE DENSITY G CC 0.9 0.9 0.902 MELT INDEX G/iσ 1.2

GAUGE AVERAGE Micron 31.9 31.9 31.9

1% SECANT MODULUS MPa MD 75.7 77.9 82.2 MPa TD 78.7 71.4 82.5

TENSILE @ YIELD MPa MD 4.69 4.65 5.39 MPa TD 4.41 4.36 4.75

ELONGATION @ YIELD % MD 8.02 7.84 7.98 % TD 7.59 8.12 7.87

ELONGATION @ BREAK % MD 529 539 564 % TD 650 666 684

ULTIMATE TENSILE MPa MD 60.9 61.3 50.8 MPa TD 49.9 50.1 50.9

EIΛiENDORF TEAR N mm MD 48.3 57.1 44.0 N/mm TD 73.0 79.1 69.9

DART IMPACT N/πun >557 >557 >557

PUNCTURE FORCE N/mm 1183 1461 1260 PUNCTURE ENERGY J/mm 96 147 110

HAZE % 1.8 2.9 1.3 GLOSS % 83.7 79 87.2

Claims

CLAIMS:I claim:

1. A polyolefin composition comprising: i) a majority component, said majority component including: a metallocene-catalyzed polyolefin selected from the group consisting of ethylene homopolymers, ethylene α-olefin copolymers, polypropylene homopolymers, polypropylene copolymers and combinations thereof; and

ii) a solid solvent present in the range of from 0.5 to 10 parts per hundred parts of said majority component wherein said solid solvent has: a) a T_ώ below the processing temperature of the blend, preferably

20° C or more below the processing temperature of the majority component; b) a T, point at least at the crystallization temperature of said polyolefin, preferably 20° C or more higher than the crystallization temperature of said majority component; c) a solubility index in the range of from 15 to 20 MPa^,/4; d) an extractability in n-hexane at 50°C temperature not exceeding 5.5 weight percent based on the total weight of the composition; e) a degradation temperature in excess of 250°C ; f) a refractive index within ±10% of said polyolefin; and wherein said solid solvent is selected from the group consisting of, monofunctional C₂₀ to C₇₀ hydrocarbons, and multifunctional C₂₀ to C₇₀ hydrocarbons, wherein said functionality is selected from the group consisting of alcohols, acids, esters, sulfonates, aldehydes, ketones, ethers, acidamides, amines and combinations thereof, preferably 1 wherein said solid solvent is a metal salt of C₂₀ to C₇₀ organic acids.

2. The polyolefin composition of claim 1 wherein said solid solvent is one of a crystalline material or a semi-crystalline material, with a melting point lower than the processing temperature of said polyolefin.

3. A blend comprising: a) a polyolefin selected from the group consisting of polyethylene, polypropylene, ethylene-alpha-olefin copolymers, propylene-ethylene copolymers, propylene-alpha-olefin copolymers and combinations thereof; and b) a solid solvent present in said blend in the range of 0.5 to 10 parts per hundred parts of said polyolefin, and wherein said polyolefin has a Mw/Mn less than 2.8; and wherein said solid solvent is selected from the group consisting of, monofunctional C₂₀ to C₇₀ hydrocarbons, and multifunctional C₂₀ to C₇₀ hydrocarbons, wherein said functionality is selected from the group consisting of alcohols, acids, esters, sulfonates, aldehydes, ketones, ethers, acidamides, amines and combinations thereof.

4. A polyethylene composition comprising: i) a majority component, said majority component including: a metallocene-catalyzed polyethylene selected from the group consisting of ethylene homopolymers, ethylene α-olefin copolymers, and combinations thereof, wherein said majority component has a density in the range of from 0.89 to 0.93 g/cc, wherein said α-olefins, if present are present in the range of from 0.2 to 20 mole percent based on the total moles of said copolymer, wherein said alpha-olefin, if present is selected from the group consisting of butene- 1 , hexene- 1 , 4- methyl pentene-1, octene-1, and mixtures thereof ; and

ii) a solid solvent present in the range of from 0.5 to 10 parts per hundred parts of said majority component, wherein said solid solvent has: a) a T_di below the processing temperature of the blend; b) a T_a point at least at the crystallization temperature of said polyolefin; c) a solubility index in the range of from 15 to 20 MPa^w; d) an extractability in n-hexane at 50°C temperature not exceeding 5.5 weight percent based on the total weight of the composition; e) a degradation temperature in excess of 300°C; f) a refractive index within ± 10% of said polyethylene, wherein said solid solvent is selected from the group consisting of, monofunctional C₂₀ to C₇₀ hydrocarbons, multifunctional C₂₀ to C₇₀ hydrocarbons, and a metal salt of a C₂₀ to C₇₀ organic acid and combinations thereof, wherein said functionality is selected from the group consisting of alcohols, acids, esters, sulfonates, aldehydes, ketones, ethers, acidamides, amines.

5. A polyolefin composition comprising: i) a majority component, said majority component including: a metallocene-catalyzed polyolefin selected from the group consisting of ethylene homopolymers, ethylene α-olefin copolymers, polypropylene homopolymers, polypropylene copolymers and combinations thereof; and

ii) a solid solvent present in the range of from 0.5 to 4 parts per hundred parts of said majority component wherein said solid solvent has: a) a Tjj below the processing temperature of the blend; b) a T, point at least at the crystallization temperature of said polyolefin; c) a solubility index in the range of from 15 to 20 MPa ; d) an extractability in n-hexane at 50°C temperature not exceeding 5.5 weight percent based on the total weight of the composition; e) a degradation temperature in excess of 250°C; f) a refractive index within ±10% of said polyolefin; and wherein said solid solvent is a C₂₀ to C₇₀ hydrocarbon.

6. A blend comprising: a) a polyolefin selected from the group consisting of polyethylene, polypropylene, ethylene-alpha-olefin copolymers, propylene-ethylene copolymers, propylene-alpha-olefin copolymers and combinations thereof; and b) a solid solvent present in said blend in the range of 0.5 to 4 parts per hundred parts of said polyolefin, and wherein said polyolefin has a Mw/Mn less than 2.8; and wherein said solid solvent is a C₂₀ to C₇₀ hydrocarbon.

7. The blend of claims 3 or 6 wherein said polyolefin is made in the presence of a metallocene catalyst.

8. The blend as recited in claims or 6 wherein said polyethylene is a polyethylene having a density in the range from 0.915 to 0.960 g/cc.

9. The blend as recited in claims 3 or 6 wherein the polyethylene is an ethylene- alpha-olefin copolymer wherein the alpha-olefin is selected from the group consisting of propene-1, butene- 1, hexene-1, 4-methyl pentene-1, octene-1, and mixtures thereof said alpha-olefin being present in said ethylene copolymer in the range of from 0.2 to 20 mole percent based on the total moles of the copolymer.

10. The blend as recited in claims 3 or 6 wherein the polyethylene is one of a homopolymer, copolymer, or teφolymer of ethylene having a density in the range of from 0.85 to 0.96 g/cc.

11. The blend as recited in claims 3 or 6 wherein the polyethylene is one of a homopolymer, copolymer, or teφolymer of ethylene having a density in the range of

12. The blend of claims 3 or 6 wherein said polypropylene copolymer is a copolymer of propylene and a comonomer selected from the group consisting of ethylene, butene- 1, 4-methyl pentene-1, hexene-1, octene-1 and mixtures thereof, wherein said comonomers are present in said propylene copolymer in the range of 0.2 to 6 mole percent based on the total moles of the propylene copolymer.

13. Use of the blend as recited in claims 5 or 8 in a film.

14. Use of the blend as recited in claims 5 or 8 in a fiber.

15. Use of the blend as recited in claim 5 or 8 in a molded article.

16. Use of the blend as recited in claims 5 or 8 in a fabric.