EP0633899A1

EP0633899A1 - Polypropylene resins and process for the production thereof

Info

Publication number: EP0633899A1
Application number: EP93908536A
Authority: EP
Inventors: Jeffrey James Vanderbilt; Horst Kurt Seeger; Joe Collier
Original assignee: Eastman Chemical Co; Huntsman Polypropylene Corp
Current assignee: Huntsman Polypropylene Corp
Priority date: 1992-03-31
Filing date: 1993-03-19
Publication date: 1995-01-18
Also published as: CA2132531A1; WO1993020115A1; MX9301815A; JPH07508769A

Abstract

Novel propylene compositions having a melt flow rate of 0.1 to 20 g/10 min at 230 °C and specified levels of crystallinity are disclosed. In addition, a process for the production of the polypropylene composition in gas-phase or slurry-phase at a temperature of 75 to 90 °C hydrogen/propylene ratios, with particular aluminum/titanium ratios, and cocatalyst/electron donor ratios is disclosed as well as a process for extruding the polypropylene compositions and the articles prepared thereby.

Description

POLYPROPYLENE RESINS AND PROCESS FOR THE PRODUCTION THEREOF

Field of the Invention The present invention relates to the process for the gas—phase or slurry—phase production of polypropylene that is generally useful for oriented film and molded articles. The present invention further relates to film forming and molding processes using the polypropylene and articles produced thereby.

Background of the Invention

A wide variety of polypropylene, both crystalline and amorphous, are commercially available. Economical processes for the production of polypropylene generally use gas-phase fluidized-bed and slurry—phase technology. The slurry—phase process is run in liquid propylene or another inert diluent whereas the gas—phase process is run in the absence of solvent/diluent which eliminates the need for costly solvent removal. The use of high- activity catalyst in both processes can result in polypropylene with low levels of catalyst residue which eliminates the need for costly catalyst removal. Unfortunately, prior to the present invention, polypropylene produced according to these technologies cannot be used in certain film applications. Since film is an extremely valuable product and both gas—phase and slurry—phase technology using the high—activity catalyst is an important method for producing most polypropylene; it would be very desirable to be able to produce, by gas—phase or slurry phase technology, polypropylene which could be economically converted into more film applications such as biaxially oriented polypropylene (BOPP) . Radiation sterilization is a method commonly used in medical applications. In addition, radiation sterilization is being used for numerous food packaging applications. Thus any polypropylene used in these applications must be radiation resistant. However, polypropylene produced using the high—activity catalyst in both gas—phase and slurry—phase processes is susceptible to degradation as initiated by high energy radiation, e.g., gamma rays. For this reason the polypropylene can not be used in applications in which high energy radiation is used. It would, therefore, be very desirable to be able to produce radiation resistant articles from polypropylene produced by gas—phase or slurry—phase technology. This is particularly true if the gas phase or slurry—phase produced polypropylene has properties comparable to polypropylene produced by prior methods (e.g., solution process) but yet is more economical by using the high—activity catalyst.

Summary of the Invention

The composition of the present invention is a polypropylene composition that comprises 99.8 mol % up to 100 mol % propylene and 0 to 0.2 mol % of another alpha—olefin wherein the polypropylene composition has a melt flow rate of 0.01 to 20 g/10 min at 230°C and specific levels of crystallinity.

An additional aspect of the present invention is a process for the production of polypropylene in the gas phase which comprises reacting under gas—phase fluidized-bed reactor conditions at a temperature of 75 to 90°C at least 50 mol % propylene, one other alpha— olefin comonomer at a comonomer/propylene molar ratio of 0 to 0.005, and hydrogen at a hydrogen/propylene molar ratio of 0.001 to 0.06 in 0 to 50 mole % inert gas carrier in the presence of a magnesium halide supported titanium halogen catalyst, an organoaluminum cocatalyst, and an electron donor wherein the aluminum/titanium molar ratio is between 30 and 150 and the cocatalyst/ electron donor molar ration is between 3 to 6. An additional aspect of the present invention is a process for the production of polypropylene in slurry- phase which comprises reacting under slurry—phase conditions at a temperature of 75 to 90°C propylene and one other alpha—olefin comono er at a comonomer/ propylene molar ratio of 0 to 0.005 and hydrogen at a hydrogen/propylene molar ratio of 0.001 to 0.06 in 0 to a minor mol % inert gas carrier in the presence of a magnesium halide supported titanium halogen catalyst, an organoaluminum cocatalyst and an electron donor wherein the aluminum/titanium molar ratio is between 30 to 150 and the cocatalyst/electron donor molar ratio is between 3 and 6.

A further aspect of the present invention entails biaxially oriented polypropylene articles and radiation— resistant molded polypropylene articles and the process for producing these articles using the inventive polypropylene composition.

Detailed Description of the Invention The applicants have unexpectedly discovered a polypropylene composition that can be formed into articles with superior orientation characteristics. These superior orientation characteristics of the polypropylene composition of the present invention can be readily observed, using standard physical property testing methodology, i.e., tensile strength at break, elongation on molded tensil bars, etc. In addition, superior migration of additives (slip and antiblock) in a film results in a lower co—efficient of friction of the final film substrate. A lower cc—efficient of friction imparts superior handling characteristics to the resultant film.

The polypropylene composition of the present invention also has superior radiation resistance. This radiation resistance is believed to be due to the lowered specific levels of crystallinity. Polypropylene produced using the high—activity catalyst is highly crystalline. High crystallinity is advantageous for many applications where high rigidity is required. However, for certain applications such as radiation resistant articles, reduced crystallinity at specific levels is believed to be important.

The polypropylene composition unexpectedly has a melt flow rate between 0.1 and 20 g/10 min at 230°C and specific levels of crystallinity. Crystallinity can be measured in several ways, i.e., xylene solubles content (Xs) , isotacticity as measured by carbon—13 nuclear magnetic resonance (NMR) . In addition, crystallinity can be measured using dynamic mechanical thermal analysis (DMTA) . Of particular value is the measurement T*. T* is the temperature at which the complex modulus (E*) = 1.4 x 10⁸ dynes/cm². The polypropylene composition of the present invention has a T* below 318°F (159°C). This combination of melt flow rate and specific crystallinity levels (T*) unexpectedly renders the inventive polypropylene composition useful for the preparation of oriented polypropylene by commercial film forming processes such as in the production of BOPP. In addition articles molded using this composition exhibit enhanced resistance to degradation initiated by radiation. The composition is generally prepared in a gas—phase fluidized—bed or in a slurry—phase process with hydrogen in the presence of a titanium catalyst and an organoaluminum cocatalyst. The inventive polypropylene composition is generally unmodified and when taken directly from a reactor has a melt flow rate at 230°C as determined by ASTM Method D 1238-85, of 0.1 to 20 grams/10 minutes and specific levels of crystallinity as measured by DMTA (T*) .

Polypropylene produced by gas—phase or slurry—phase technology is known to skilled in the art. Compositions of the invention can be prepared using standard gas- phase or slurry—phase technology reactors. Catalyst, cocatalyst, and electron donor are well known to those skilled in the art. Examples are disclosed in U.S. patent 3,418,346, U.S. Patent 4,400,302, U.S. Patent 4,414,132, and U.S. patent 4,329,253, the disclosures of which are incorporated herein by reference in their entirety.

The preferred magnesium halide supported titanium halogen catalyst used in the gas—phase process of the present invention is titanium tetrachloride on magnesium chloride. The organoaluminum compound can be chosen from any of the known activators in catalyst systems comprising titanium halides. Thus aluminum trialkyl compounds, dialkylaluminum halides and dialkylaluminum alkoxides may be successfully used. Aluminum trialkyl compounds are preferred, particularly those wherein each of the alkyl groups has 2 to 6 carbon atoms, e.g., aluminum triethyl, aluminum tri— n—propyl, aluminum tri— isobutyl and aluminum tri— n- ropyl , aluminum tri— isopropyl and aluminum dibutyl--α-amyl. The preferred organoaluminum cocatalyst is selected from trialkylaluminum compounds with triethylaluminum being most preferred.

Suitable electron donors are ethers, esters, ketones, phenols, amines, amides, imines, nitriles, phosphines, phosphites, stibines, arsines, phosphoramides and alcoholates. Examples of suitable electron donors are those referred to in U.S. Patent No. 4,136,243 and German Offenlegungesschrift No. 2,729,196. Preferred electron donors are esters and diamines, particularly esters of aromatic carboxylic acids, such as ethyl and methyl benzoate, para—methyoxyethyl benzoate, para—ethoxymethyl benzoate, para—ethyoxyethyl benzoate, ethyl aerylate, methyl methacrylate, ethyl acetate, dimethyl carbonate, dimethyl adipate, dihexyl fumerate, dibutyl maleate, ethyl isopropyl oxalate, ethyl para—chlorobenzoate, hexyl para—amino benzoate, isopropyl naphthanate, 22-amyl toluate, ethyl cyclohexanoate, propyl pivalate, N,N,N' ,N'—tetramethyl ethylene diamine, l,2,4—trimethyl piperazine, and 2,3, ,5—tetraethyl piperidine compounds, with para— ethoxyethyl benzoate being most preferred.

In the reaction process of the present invention the aluminum/titanium molar ratio is between 30 and 150, preferably between 35 and 70 with between 40 and 60 being most preferred. A molar ratio of aluminum/titanium much above 150, is wasteful with respect to the organoaluminum component and high ratios result in excessively high levels of residual aluminum in the polymer. A molar ratio of aluminum/titanium below 30 results in a very sluggish reaction with low production rates, low titanium catalyst productivity, i.e., high levels of titanium catalyst residues.

In the reaction process of the present invention the cocatalyst/electron donor molar ratio is between 3 and 6, preferably between 3.2 and 5.0 with between 3.5 and 4.0 being most preferred. At a cocatalyst to electron donor molar ratio of much above 6, excessively high levels of xylene soluble content polymer may form. The xylene solubles content polymer may be sticky and difficult to transfer out of the reactor. If xylene solubles content is sufficiently high, the transfer of the polymer from the reactor becomes practically impossible. In addition high xylene solubles content polymer may exhibit undesirable exudation when extruded as a thin film. If cocatalyst to electron donor molar ratio is much below 3, a polymer is produced that does not make satisfactory oriented film and is outside the scope of the present invention, i.e., T* is too high.

In the process to produce the homopolymer or near homopolymer, the hydrogen/propylene molar ratio during the reaction is between 0.001 and 0.06 and the comonomer is preferably ethylene at an ethylene/ propylene molar ratio of no greater than 0.001; or 1—butene, 1—hexene or 4-methyl—1-pentene at a comonomer/propylene molar ratio of no greater than 0.005. The hydrogen/propylene molar ratio during the polymerization process is preferably between 0.002 and 0.03, with a ratio between 0.005 and 0.01 being more preferred.

The process of the present invention must be carried out at a temperature between 75 and 90°C at a total pressure between 300 and 1000 psi, more preferably between 75 and 80°C at 400 to 600 psi.

The amount of propylene used in the gas—phase process of the present invention is at least 50 mol % in the presence of no more than 50 mol % of an inert carrier gas such as nitrogen. The amount of propylene monomer in the reactor or total monomers if a comonomer is used, is preferably between 60 and 100 mol %. At higher levels of inert gas the reaction rate drops off without achieving much benefit from the added fluidization. The inert carrier gas is not a requirement since the monomers can provide fluidization to the catalyst bed.

In a slurry process, the reaction can take place in a liquified pool of propylene. Alternatively, the process can be carried out in an inert diluent. The diluent must not contain functionality that can react with the catalyst of alkylaluminu agent. Examples of suitable diluents include: isopentane, hexane, heptane, octane. A description of the general slurry phase processes can be found in The Encyclopedia of Polymer Science and Engineering. Vol .13., pp. 502—510.

The polypropylene produced according to the inventive process is crystalline in nature but yet has the defined level of crystallinity as determined by T* and the defined melt flow rate. As discussed above, the xylene solubles content of the polypropylene varies with the cocatalyst/electron donor molar ratio. The T* value for polypropylene is less than 318°F (159°C), preferably between 311°F (155°C) and 318°F (159°C) with between 312°F (156°C) and 315°F (157°C) being more preferred. For the purposes of comparison, typical gas—phase or slurry—phase produced polypropylene has a T* = 321°F (>160°C) . We have discovered that polypropylene with T* greater than 318°F (159°C) produces inferior BOPP and when converted into molded articles, inferior radiation resistance properties are also observed.

The melt flow rate of the inventive polypropylene is between 0.1 and 20 g/10 min at 230°C (as determined in the characterization section to follow) , preferably between 2 and 10 g/10 min, more preferably between 3 and 8 g/10 min. A melt flow rate below 0.1 g/10 min gives a polymer which is difficult to process. While a melt flow rate above 20 g/10 min gives a polymer with low melt strength and low melt viscosity, i.e., it becomes too runny for film forming applications.

The polypropylene produced by the inventive gas- phase and slurry processes, while having the different properties mentioned above (melt flow rate and T*) retains many of the characteristics of polypropylene produced by standard gas—phase and slurry processes. The polypropylene of the present invention as with other gas-phase and slurry produced polypropylene, has a significantly higher stereoregularity than polypropylene produced by the solution process. An example of the solution process is disclosed in U.S. Patent No. 3,272,788.

The polypropylene produced by the gas—phase or slurry—phase process and according to the present invention has other characteristics that are different from polypropylene produced by a solution process. They include: residue from high activity catalyst; higher melting point (2°C high, e.g., the melting point for homopolymer is generally greater than 159°C) as determined by differential scanning calorimetry (DSC) ; higher crystallinity as determined by X—ray diffraction; lower heptane solubles content (at least 10 percent lower); high tensile strength as determined by A.S.T.M. Method D-633.

The polymers of the invention can be compounded with additives such as antioxidants, stabilizers for inhibiting degration by heat, ultraviolet light and weathering, opaqueing pigments such as titanium dioxide and carbon black, plasticiziers, slip agents, antiblocking agents, tackifying resins and small amounts (less than 20 percent) or other compatible polymers.

The blend compositions can be prepared in various ways, such as dry blending, dry blending and then passing through a compounding extruder, compounding on a milling roll, or in a Banbury mixer, by fusion, or by solution blending. Any method whereby the components can be blended together will produce the desired blend. For example, fine pellets of each polymer, having an average size of 1/16 inch (0.16 cm) with up to 20 percent of the pellets being 1/8 inch (0.32 cm) in diameter with some pellets being smaller than 1/16 inch (0.16 cm) , are blended mechanically, and the blend is fed to an extruder wherein it is fused and extruded.

The melt can be converted into film such as BOPP at melt temperatures of up to 325°C although melt temperatures in the range of 210 to 295°C are preferred and have been found to give excellent results with maximum useable line speeds with a minimum of defects.

Thus, another aspect of the present invention entails a ilm forming or molded article forming process that comprises extruding or injection molding at elevated temperatures a polypropylene composition comprising 99.8 to 100 mol % propylene and 0 to 0.2 mol % of at least one other alpha—olefin wherein the polypropylene has a melt flow rate of 0.1 to 20 g/10 min at 230°C and a T* less than 318°F (159°C);

This invention can be further illustrated by the

- following examples of preferred embodiments thereof, although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated.

EXAMPLES

General

Slurry Reactor

The slurry reactor used was a one—gallon capacity autoclave obtained from Autoclave Engineers. Purified (polymerization grade) propylene was used.

Triethylaluminum (TEAL) was obtained from Aldrich Chemical Company as a 25 percent (wt) solution in toluene. Para—ethoxyethyl benzoate (PEEB) obtained from Elan Chemical Company was used neat. Catalyst (TiCl₄ supported on MgCl₂) with titanium (Ti) content was ~0.5 percent (wt) , TEAL, and PEEB were weighed in a dry box using a analytical balance and added to a dry (heated at 80°C overnight) charge bomb. The charge bomb was a modified check valve without the check fitted with American Instruments valves. Before each run, the autoclave was "sweetened", i.e., it was charged with 1600 L of 0.5 percent TEAL solution, heated to 100°C under N₂, cooled to ambient temperature, and the TEAL was drained. After cooling, 2 L of liquid propylene and 15 psi H₂ were added. The autoclave was heated to 50°C. Contents of the charge bomb were pressured into the autoclave with nitrogen. The autoclave was heated to the desired temperature, held at that temperature for 1 hour, and cooled to ambient temperature. The contents were removed and analyzed (see below) .

Gas—Phase Reactor

A continuous reactor was used for the production of polypropylene (PP) powder. All gas components were purified to remove known catalyst poisons. A gas composition of propylene at 70 mole percent was maintained. Hydrogen concentration was varied to produce the desired melt flow rate (MFR) PP. The remainder of the gas composition was made up of nitrogen and minor amounts of inert impurities. The reactor bed temperature was maintained at 67°C. The total pressure was 535 psi. The bed was fluidized by maintaining a cycle gas flow of 19,000 cubic feet/hour (150,000 cubic cm/sec) . Catalyst was fed continuously to the reactor. TEAL was continuously fed as a dilute solution in isopentane. The molar ratio of aluminum/titanium (Al/Ti) was between 50—60. The electron donor, PEEB, was continuously fed as a dilute solution in isopentane. The molar ratio of TEAL/PEEB was varied to prepare the desired product. Polypropylene powder was discharged from the reactor at periodic intervals in order to give a constant bed weight. The powder was deactivated by treatment with steam.

Compounding

The powder was compounded with the additive system of choice using either a 3.5—inch Modern Plastics Machinery single—screw extruder or a 40—millimeter

Berstorff twin—screw extruder. The additive system of choice can be chosen based on technology well known to those skilled in the art. Examples of additive systems found to be effective are blends comprised of (amounts are based on the weight of the entire extrusion coating system): 0 to 2,000 parts per million primary antioxidant, e.g., hindered phenol; 0 to 2,000 parts per million secondary antioxidant, e.g., phosphite ester; 0 to 3,000 parts per million synergistic antioxidant, e.g., thioester; 0 to 2,000 parts per million acid scavenger. A specific example of a hindered phenol is tetrakis[methylene 3—(3,5—di—tert—buty1—4'— hydroxyphenyl)propionate] ethane (under the trademark Irganox 1010 available from Ciba Geigy) . A specific example of a phosphite ester is tri (mono and dinonylphenyl) phosphite (under the trademark Naugard PHR available from Uniroyal Chemical Company) . A specific example of a thioester is distearyl thiodipropionate (DSTDP) . A specific example of an acid scavenger is calcium stearate.

Thin—Film Composition

A composition for thin film applications is typically made by extrusion compounding an intimate mix of polymer with antioxidants, acid scavengers, and coefficient of friction reducers familiar to the trade. A suitable additive package would be 0.1% Irganox 1010, 0.1% Irgafos 168, 0.04% Hydrotalcite DHT4A, and 0.3% Amide E. This composition is extruded and pelletized in a twin—screw extruder at a melt temperature of 225°C.

Thin—Film Production

A relatively thick sheet (15 to 40 mils) is cast in a continuous process onto chilled rolls or by submersion in cool water. It is then moved through a series of oil heated draw rolls, where increasing speeds between the rolls draw the sheet thinner by a ratio of 4 to 6:1. These machine direction dimensional changes are then annealed in place with oil heated rolls and the thinned sheet passes into a hot air oven where contact is made with the tentering frame clamps that grasp the edges of the sheet. After being pulled through a preheat section where the sheet is heated to above 250°F, but below the melting point, the sheet is stretched in the transverse direction to a final, desired film thickness. This final stretch can be as much as 10:1. After this, the stretch film is passed through an annealing section to set the width and is released from the tenter frame and wound onto a set of wind up rolls as a thin film.

Characterization

The resins were characterized using standard analytical testing methodology. MFR was determined using ASTM Method D 1238—85. Xs was determined by dissolution of the polymer in refluxing xylene. The solution was allowed to cool to 25°C to effect crystallization. Xs and decalin solubles were determined by measuring the concentration of polymer that remained in the solvent at 25°C. Melting point was determined by differential scanning calorimetry (DSC) using ASTM Method D—3418. Melting point (T ) , heat of fusion (ΔHf) , crystallization temperature (Tc) , and heat of crystallization (ΔHc) were obtained on a second heating cycle. Test specimens were prepared for physical property evaluation by injection molding using an Arbug 305 S injection molding machine. Physical properties were obtained using standard methodology, see Table 1.

Table 1 Methods for Physical Property Determination Test ASTM Method

Flexural Modulus D790—66

Tensile D-638

Density D—1505

Melt Flow Rate D-1238-85 Vicat Softening Pt. D—1525

Rockwell Hardness D—785

Izod Impact D—256

Heat Deflection D-648

Gardner Impact D—3029

Melting point was determined by differential scanning calorimetry (DSC) . Isotacticity was determined by carbon—13 nuclear magnetic resonance (NMR) using a JEOL GSX 270 at 270 megahertz using triad level analysis. The peaks at 19.85 to 20.50 ppm were assigned as rr; peaks at 20.50 to 21.20 ppm were assigned as mr; peaks at 21.20 to 22.50 ppm were assigned as mm. Isotacticity was definied as [mm/(mm + mr + rr) ] X 100. Productivity can be calculated from the polymer produced/catalyst fed or from the level of residual Ti in the PP. T* was determined using dynamic mechanical thermal analysis (DMTA) using a Rheometrics RSA—II instrument using die cut thick film samples with dimensions ca. 0.75 mm x 23 mm. The films were compression molded on an automated PHI press. The specimens were tested in dynamic tension at 17.5 radians/second an 0.1 percent strain in the temperature ramp mode from 120 to 170°C at 1 degree/minute. T* is the temperature at which the complex modulus (E*) = 1.4 X 10⁸ dynes/cm². Molecular weight distribution of the PP samples was analyzed by size—exclusion chromatography (SEC) using a Waters 150C GPC System with refractive index detector. The column set consisted of 2 Waters' Linear (loVloVlO⁶) "Microstyragel-HT" columns. Calibration was done using a single broad PP standard with Mw = 267000, Mn = 43000. The samples were run in o— diclorobenzene at 143°C. Thus, the results are relative, and should not be quantitatively compared to Mn numbers by other methods. The SPC ranges for a standard are given below:

The following four examples were produced according to the slurry—phase process.

Example 1

Contents of the charge bomb, i.e., 1.05 g of TEAL solution, 0.13 g of PEEB, and 0.31 g of catalyst were charged to the autoclave. The temperature was increased to 80°C. Analysis of the product was as follows: 688 g; residuals, Ti = 4.0 ppm, Al = 271 ppm, Cl = 32 ppm, PEEB = 169 ppm; MFR = 10.1 g/10 min; Xs = 12.4 percent; T* = 310.4°F (154°C) ; Tm = 160.3°C; ΔHf = 82.5 Joules/gram; Tc = 110.4°C; Isotacticity = 91.9 percent; MWd = 6.4; productivity = 10,600 pounds (kg) PP/pound (kg) of catalyst (dry basis) .

Example 2 (Comparative.

Contents of the charge bomb, i.e., 0.99 g of TEAL solution, 0.17 g of PEEB, and 0.28 g of catalyst were charged to the autoclave. The temperature was increased to 60°C. Analysis of the product was as follows: 295 g; residuals, Ti = 4.6 ppm, Al = 240 ppm, Cl = 50 ppm, PEEB

= 892 ppm; MFR = 1.23 g/10 min; Xs = 4.4 percent; T* = 321.5°F (161°C) ; Tm = 159.4°C; ΔHf = 84.3 Joules/gram;

Tc = 109.0°C; Isotacticity = 95.1 percent; MWd = 4.5; productivity = 5000 pounds (kg) PP/pound (kg) of catalyst (dry basis) .

Example 3 (^{^}Comparative.

Contents of the charge bomb, i.e., 0.99 g of TEAL solution, 0.15 g of PEEB, and 0.29 g of catalyst were charged to the autoclave. The temperature was increased to 70°C. Analysis of the product was as follows: 591 g; residuals, Ti = 2.2 ppm, Al = 128 ppm, Cl = 43 ppm, PEEB = 278 ppm; MFR = 0.98 g/10 min; Xs = 4.2 percent; T* = 321.1°F (161°C); Tm = 159.6°C; ΔHf = 89.0 Joules/gram; Tc = 111.2°C; Isotacticity = 95.0 percent; MWd = 5.3, productivity = 9700 pounds (kg) PP/pound (kg) of catalyst (dry basis) .

Example 4 fComparative.

Contents of the charge bomb, i.e., 1.01 g of TEAL solution, 0.17 g of PEEB, and 0.28 g of catalyst were charged to the autoclave. The temperature was increased to 80°C. Analysis of the product was as follows: 223 g; residuals, Ti = 7.1 ppm. Al = 240 ppm, Cl = 66 ppm, PEEB = 937 ppm; MFR = 1.06 g/10 min; Xs = 2.2 percent; T* = 325.2°F (163°C); Tm = 160.6°C; ΔHf = 100.3 Joules/gram; Tc = 111.5°C; Isotacticity = 98.4 percent; MWd = 4.5; productivity = 3800 pounds (kg) PP/pound (kg) of catalyst (dry basis) .

Table 2 Data from Slurry Phase Results

Example

Gas Phase Process

The following five examples were produced using the gas—phase process.

Example 5

The gas phase reactor was run at a TEAL/PEEB molar ratio = 4.0, temperature = 80°C, H_j/propylene molar ratio = 0.003. Analysis of the product gave the following: residuals, Ti = 2.4 ppm, Al = 54 ppm, PEEB = 119 ppm; MFR = 4.5 g/10 min; Xs = 7.5 percent; Ds = 9.3 percent; T* = 318.0°F (159°C) ; Tm = 160.1°C; ΔHf = 90.0 Joules/gram; Tc = 114.7°C; Isotacticity = 92.6 percent; MWd = 4.0; productivity = 8700 pound (kg) PP/pound (kg) of catalyst (dry basis) .

Example 6 (Comparative.

The gas phase reactor was run at a TEAL/PEEB molar ratio = 2.5, temperature = 80°C, H₂/propylene molar ratio = 0.015. Analysis of the product gave the following: residuals, Ti = 7.4 ppm, Al = 74 ppm, PEEB = 203 ppm; MFR = 5.0 g/10 min; Xs = 5.5 percent; Ds = 6.9 percent; T* = 321.6°F (161°C) ; Tm = 163.6°C; ΔHf = 81.1 Joules/gram; Tc = 112.2°C; Isotacticity = 94.7 percent; MWd = 4.8; productivity = 7200 pound (kg) PP/pound (kg) of catalyst (dry basis) .

Example 7 fComparative)

The gas phase reactor was run at a TEAL/PEEB molar ratio = 3.5, temperature = 60°C, H₂/propylene molar ratio = 0.022. Analysis of the product gave' the following: residuals, Ti = 2.2 ppm, Al = 43 ppm, PEEB = 110 ppm; MFR = 5.0 g/10 min; Xs = 6.3 percent; Ds = 7.5 percent; T* = 322.0°F (161°C) ; Tm = 163.4°C; ΔHf = 77.6 Joules/gram; Tc = 113.4°C; Isotacticity = 95.6 percent; MWd = 8.6; productivity = 10500 pound (kg) PP/pound (kg) of catalyst (dry basis) .

Example 8 (Comparative) The gas phase reactor was run at a TEAL PEEB molar ratio = 2.5, temperature = 60°C, H_j/propylene molar ratio = 0.030. Analysis of the product gave the following: residuals, Ti = 3.1 ppm, Al = 55 ppm, PEEB = 250 ppm; MFR = 4.9 g/10 min; Xs = 6.7 percent; Ds = 8.0 percent; T* = 319.4°F (160°C); Tm = 162.1°C; ΔHf = 74.7

Joules/gram; Tc = 111.7°C; Isotacticity = 96.4 percent; MWd = 5.8; productivity = 7400 pound (kg) PP/pound (kg) of catalyst (dry basis) .

Example 9 fComparative)

The gas phase reactor was run at a TEAL PEEB molar ratio = 4.0, temperature = 70°C, Hj/propylene molar ratio = 0.005. Analysis of the product gave the following: residuals, Ti = 1.9 ppm, Al = 45 ppm, PEEB = 250 ppm; MFR = 1.6 g/10 min; Xs = 6.0 percent; Ds = 8.0 percent; T* = 319.5°F (160°C) ; Tm = 159.3°C; ΔHf = 94.0 Joules/gram; Tc = 110.0°C; Isotacticity = 95.0 percent; MWd = 5.1; productivity — 17300 pound (kg) PP pound (kg) of catalyst (dry basis) .

Table 3 Gas Phase Results

Example

Comparative

Comparative Feeds: TEAL/PEEB 2.5 4.0 Temp., °C 60 70

Product: MFR, g/10 min 4.9 1.6 Xs, % 6.7 6.0 I Al, ppm 55 45.0 TI, ppm 3.1 1.9 PEEB, ppm 252 251.0 Isotact., % 96.4 95.0 T*, °F (°C) 319.4 (160) 319.5(160) Ds, % 8.0 8.0 MWd 5.8 5.1

Tm, °C 162.1 159.3

Ht. Fus. , J/g 74.73 94.0 Tc, °C 111.7 110.0

Prod. , lb PP/lb 7420 17300 cat

Discussion of Examples

As shown above. Examples 1 and 5 of the present invention had the specific crystallinity (as specified by T* < 318°F (159°C)) needed to fabricate oriented film. Composition prepared in the comparative examples by the prior art processes did not have the specific crystallinity (as specified by T* < 318°F (159°C)) needed to fabricate oriented film.

Physical Properties

Samples of the invention were molded into test specimens. Physical property measurements were made using standard testing methodology, see above. Materials of the invention (Example 1) gave high tensile strength at break and high elongation at break. This indicates that the materials of the present invention increases in strength during orientation.

Table 4 Physical Properties

Example 6 7

Comparative Comparative Comparative

REACTION CONDITIONS:

TEAL, g 4 . 0 2 . 5 3 . 5 4.0

Temperature °C 80 80 60 70

PHYSICAL PROPERTIES: UNITS

Density g/cc 0.9037 0. 911 0.91 0.9095

(Annealed)

Yellowness Index; pellets

Yellowness Index; plaques

Tensile

Str. (2"/min) (5 cm/mm)

@ break psi (kPa) >3670 (>25,300) 3110 (21,500) 2790 (19,300) 3050 (21,0

Tensile

Str. (2" min) (5 cm mm) θ yield psi (kPa) 4360 (30,000) 4820 (33,200) 4820 (33,300) 4830 (33,3

Elongation

(2"/min) (5 cm/mm)

@ break > 630 490 170 235

12 12 12 12

Table 4 Physical Properties Cont'd.

Example

Comparative Comparative Comparative

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

1. A process for the production of polypropylene . comprising reacting at a temperature of 75 to 90°C at least 50 mol % propylene, one other alpha—olefin comonomer at a comonomer/ propylene molar ratio of 0 to 0.005, and hydrogen at a hydrogen/propylene molar ratio of 0.001 to 0.06 in 0 to 50 mol % inert gas carrier in the presence of a magnesium halide supported titanium halogen catalyst, an organoaluminum cocatalyst, and an electron donor wherein the aluminum/titanium molar ratio is between 30 and 150 and the cocatalyst/electron donor molar ratio is between 3 and 6.

2. The process according to Claim 1 wherein the comonomer is ethylene at an ethylene/propylene molar ratio of no greater than 0.001; or 1—butene, 1—hexene, or 4—methyl—1—pentene at a comonomer/propylene molar ratio of no greater than 0.005.

3. The process according to Claim 1 wherein the titanium halogen catalyst is titanium tetrachloride, the organoaluminum cocatalyst is triethylaluminum and, the electron donor is para—ethoxyethyl benzoate.

4. The process according to Claim 3 wherein the triethylaluminum/para—ethoxyethyl benzoate molar ratio is between 3.2 and 5.

5. The process according to Claim 1 wherein the tempera ure is between 75 and 80°C.

6. The process according to Claim 1 wherein the total pressure of the reaction is between 300 and 1000 psi.

7. The process according to claim 1 wherein the reaction is conducted under gas—phase fluidized-bed reactor conditions.

8. The process according to claim 1 wherein the reaction is conducted under slurry—phase reactor conditions, and the inert gas carrier is present in no more than a very minor amount.

9. A process for the production of polypropylene comprising reacting at a temperature of 75 to 80°C, at least 75 mol % propylene, one other alpha—olefin comonomer at a comonomer/propylene molar ratio of 0 to 0.001 and hydrogen at a hydrogen/propylene molar ratio of 0.001 to 0.02 in 0 to 25 mol % inert gas carrier in the presence of a magnesium halide supported titanium halogen catalyst, an organoaluminum cocatalyst and an electron donor wherein the aluminum/titanium molar ratio is between 40 and 70 and the cocatalyst/electron donor molar ratio is between 3 and 4.

10. A polypropylene composition comprising 99.8 to 100 mol % propylene and 0 up to 0.2 mol % of at least one other alpha-olefin wherein the polypropylene has a melt flow rate of 0.1 to 20 g/10 min at 230°C and a T* less than 318°F (159°C) .

11. The composition according to Claim 10 wherein the T* is between 311°F (155°C) and 318°F (159°C) .

12. The composition according to claim 10 wherein the melt flow rate is 2 to 10 g/10 min at 230°C.

13. The composition according to Claim 10 further comprising up to 10 weight percent of at least one additive selected from antioxidants, stabilizers, slip agents, antiblocking agents, pigments, plasticizers, tackifying resins, compatible polymers and mixtures thereof.

14. An article forming process comprising extruding at elevated temperatures a composition comprising 99.8 to 100 mol % propylene and 0 up to 0.2 mol % of at least one other alpha—olefin wherein the polypropylene has a melt flow rate of 0.1 to 20 g/10 min at 230°C and a T* less than 318°F (159°C) .

15. The process according to claim 14 wherein the propylene composition has a melt flow rate of 2 to 10 g/10 minutes at 230°C.

16. The process according to claim 14 wherein the composition is extruded in a thin film.

17. The process according to claim 14 wherein the composition is extruded into a mold.

18.^" An article of manufacture comprising a film made from the composition of Claim 10.

19. A molded article of claim 10.