High melt strength polymers and method of making same

Abstract

A polymer composition that has a backbone chain; and a plurality of long chain branches connected to the backbone is described. The polymer composition also has a value of ²g′_LCB-¹g′_LCB g′_2LCB-g′_1LCB that is less than about 0.22, where ¹g′_LCB g′_2LCB is the long chain branching index for a fraction of the composition having a M_w of 100,000 and ²g′_LCB g′_1LCB is the long chain branching index for a fraction of the composition having a M_w of 500,000.

Description

PRIOR RELATED APPLICATIONS

This application is a divisional application of U.S. patent application Ser. No. 10/100,687, filed Mar. 15, 2002, now U.S. Pat. No. 6,875,816, which claims benefit of U.S. Provisional Patent Application No. 60/276,719, filed Mar. 16, 2001, each of which is incorporated by reference herein in its entirety.

FEDERALLY SPONSORED RESEARCH STATEMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

FIELD OF THE INVENTION

This invention relates to polyolefins with improved properties and methods of making the polyolefins.

BACKGROUND OF THE INVENTION

Ethylene homopolymers and copolymers are a well-known class of olefin polymers from which various plastic products are produced. Such products include films, fibers, coatings, and molded articles, such as containers and consumer goods. The polymers used to make these articles are prepared from ethylene, optionally with one or more copolymerizable monomers. There are many types of polyethylene. For example, low density polyethylene (“LDPE”) is generally produced by free radical polymerization and consists of highly branched polymers with long and short chain branches distributed throughout the polymer. However, films of LDPE have relatively low toughness, low puncture resistance, low tensile strength, and poor tear properties, compared to linear-low density polyethylene (“LLDPE”). Moreover, the cost to manufacture LDPE is relatively high because it is produced under high pressures (e.g., as high as 45,000 psi) and high temperatures. Most LDPE commercial processes have a relatively low ethylene conversion. As such, large amounts of unreacted ethylene must be recycled and repressurized, resulting in an inefficient process with a high energy cost.

A more economical process to produce polyethylene involves use of a coordination catalyst, such as a Ziegler-Natta catalyst, under low pressures. Conventional Ziegler-Natta catalysts are typically composed of many types of catalytic species, each having different metal oxidation states and different coordination environments with ligands. Examples of such heterogeneous systems are known and include metal halides activated by an organometallic co-catalyst, such as titanium chloride supported on magnesium chloride, activated with trialkyl aluminum. Because these systems contain more than one catalytic species, they possess polymerization sites with different activities and varying abilities to incorporate comonomer into a polymer chain. The consequence of such multi-site chemistry is a product with poor control of the polymer chain architecture, when compared to a neighboring chain. Moreover, differences in the individual catalyst site produce polymers of high molecular weight at some sites and low molecular weight at others, resulting in a polymer with a broad molecular weight distribution and a heterogeneous composition. Consequently, the molecular weight distribution of such polymers is fairly broad as indicated by M_w/M_n (also referred to as polydispersity index or “PDI” or “MWD”) Due to the heterogeneity of the composition, their mechanical and other properties are less desirable.

Recently, a new catalyst technology useful in the polymerization of olefins has been introduced. It is based on the chemistry of single-site homogeneous catalysts, including metallocenes which are organometallic compounds containing one or more cyclopentadienyl ligands attached to a metal, such as hafnium, titanium, vanadium, or zirconium. A co-catalyst, such as oligomeric methyl alumoxane, is often used to promote the catalytic activity of the catalyst. By varying the metal component and the substituents on the cyclopentadienyl ligand, a myriad of polymer products may be tailored with molecular weights ranging from about 200 to greater than 1,000,000 and molecular weight distributions from 1.0 to about 15. Typically, the molecular weight distribution of a metallocene catalyzed polymer is less than about 3, and such a polymer is considered as a narrow molecular weight distribution polymer.

The uniqueness of metallocene catalysts resides, in part, in the steric and electronic equivalence of each active catalyst molecule. Specifically, metallocenes are characterized as having a single, stable chemical site rather than a mixture of sites as discussed above for conventional Ziegler-Natta catalysts. The resulting system is composed of catalysts which have a singular activity and selectivity. For this reason, metallocene catalyst systems are often referred to as “single site” owing to their homogeneous nature. Polymers produced by such systems are often referred to as single site resins in the art.

With the advent of coordination catalysts for ethylene polymerization, the degree of long-chain branching in an ethylene polymer was substantially decreased, both for the traditional Ziegler-Natta ethylene polymers and the newer metallocene catalyzed ethylene polymers. Both, particularly the metallocene copolymers, are substantially linear polymers with a limited level of long chain branching or linear polymers. These polymers are relatively difficult to melt process when the molecular weight distribution is less than about 3.5. Thus, a dilemma appears to exist—polymers with a broad molecular weight distribution are easier to process but may lack desirable solid state attributes otherwise available from metallocene catalyzed copolymers. On the contrary, linear or substantially linear polymers catalyzed by a metallocene catalyst have desirable physical properties in the solid state but may nevertheless lack the desired processability when in the melt.

In blown film extrusion, the bubble stability is a relatively important process parameter. If the melt strength of the polymer is too low, the bubble is not stable and thus affects the film quality. Therefore, it is desirable to produce polymers with relatively high melt strength. For these reasons, there is a need for a polymer and polymerization processes which could produce a polymer with melt processing characteristics similar to or better than LDPE (i.e., high melt strength) while exhibiting solid state properties comparable to a metallocene-catalyzed polymer.

SUMMARY OF THE INVENTION

Embodiments of the invention provide a process of making a polymer comprising (a) contacting one or more olefinic monomers in the presence of at least a high molecular weight (HMW) catalyst and at least a low molecular weight (LMW) catalyst in a polymerization reactor system; and (b) effectuating the polymerization of the one or more olefinic monomers in the polymerization reactor system to obtain an olefin polymer, wherein the LMW catalyst has an R_v^L, defined as

$R_v^L=\frac{\left[\mathrm{vinyl}\right]}{\left[\mathrm{vinyl}\right]+\left[\mathrm{vinylidene}\right]+\left[\mathrm{cis}\right]+\left[\mathrm{trans}\right]}$
wherein [vinyl] is the concentration of vinyl groups in the olefin polymer produced by the low molecular weight catalyst expressed in vinyls/1,000 carbon atoms; [vinylidene], [cis] and [trans] are the concentration of vinylidene, cis and trans groups in the olefin polymer expressed in the number of the respective groups per 1,000 carbon atoms, of greater than 0.12, and wherein the HMW catalyst has a reactivity ratio, r₁ of about 5 or less. In other embodiments the low molecular weight catalyst has an R_v^L value that is greater than about 0.45, or greater than about 0.50. The high molecular weight catalyst of some embodiments has a reactivity ratio, r₁ that is about 4 or less, or about 3 or less. Some processes of the invention comprises catalyst pairs in which the R_v^L/R_v^H ratio is about 0.80 to about 1.40.

In some embodiments of the process the high molecular weight catalyst has an R_v^H defined as

$R_v^H=\frac{\text{[vinyl]}}{\text{[vinyl] + [vinylidene] + [cis] + [trans]}}$
wherein [vinyl] is the concentration of vinyl groups in the olefin polymer produced by the low molecular weight catalyst expressed in vinyls/1,000 carbon atoms; [vinylidene], [cis] and [trans] are the concentration of vinylidene, cis and trans groups in the olefin polymer expressed in the number of the respective groups per 1,000 carbon atoms, and wherein a ratio of R_v^L/R_v^H ranges from 0.5 to about 2.0. In some processes g′₂-g′₁

The molecular weight averages are determined from GPC with a light scattering detector to properly account for long chain branching and comonomer. Since all of the polymer segments under the low molecular weight peak originate from the low molecular weight catalyst, the comonomer distribution will be constant throughout the low molecular weight peak. Therefore, the presence of comonomer does not complicate the analysis.

The amount of long chain branching can also be determined by fitting the predicted molecular weight distribution to the deconvoluted LMW peak. The first step of this approach is to determine the probabilities of branching and termination based on input values of the molecular weight of the low molecular weight component,
wherein L* is a neutral Lewis base; (L*−H)+ is a Bronsted acid; A^d− is an anion having a charge of d−, and d is an integer from 1 to 3. More preferably A^d− corresponds to the formula: [M′Q₄]⁻, wherein M′ is boron or aluminum in the +3 formal oxidation state; and Q independently each occurrence is selected from hydride, dialkylamido, halide, hydrocarbyl, hydrocarbyloxide, halosubstituted-hydrocarbyl, halosubstituted hydrocarbyloxy, and halo-substituted silylhydrocarbyl radicals (including perhalogenated hydrocarbyl-perhalogenated hydrocarbyloxy- and perhalogenated silylhydrocarbyl radicals), the Q having up to 20 carbons with the proviso that in not more than one occurrence is Q halide. Examples of suitable hydrocarbyloxide Q groups are disclosed in U.S. Pat. No. 5,296,433.

In a more preferred embodiment, d is one, that is, the counter ion has a single negative charge and is A⁻. Activating cocatalysts comprising boron which are particularly useful in the preparation of catalysts of this invention may be represented by the following general formula:
(L*−H)⁺(M′Q₄)⁻;  Formula VIII
wherein L* is as previously defined; M′ is boron or aluminum in a formal oxidation state of 3; and Q is a hydrocarbyl-, hydrocarbyloxy-, fluorinated hydrocarbyl-, fluorinated hydrocarbyloxy-, or fluorinated silylhydrocarbyl-group of up to 20 non-hydrogen atoms, with the proviso that in not more than one occasion is Q hydrocarbyl. Most preferably, Q in each occurrence is a fluorinated aryl group, especially a pentafluorophenyl group. Preferred (L*−H)⁺ cations are N,N-dimethylanilinium, N,N-di(octadecyl)anilinium, di(o-ctadecyl)methylammonium, methylbis(hydrogenated tallowyl)ammonium, and tributylammonium.

Illustrative, but not limiting, examples of boron compounds which may be used as an activating cocatalyst are tri-substituted ammonium salts such as: trimethylammonium tetrakis(pentafluorophenyl)borate; triethylammonium tetrakis(pentafluorophenyl)borate; tripropylammonium tetrakis (pentafluorophenyl)borate; tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate; tri(sec-butyl)ammonium tetrakis(pentafluorophenyl)borate; N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate; N,N-dimethylanilinium n-butyltris(pentafluorophenyl) borate; N,N-dimethylanilinium benzyltris(pentafluorophenyl) borate; N,N-dimethylanilinium tetrakis(4-(t-butyldimethylsilyl)-2, 3, 5, 6-tetrafluorophenyl) borate; N,N-dimethylanilinium tetrakis(4-(triisopropylsilyl)-2, 3, 5, 6-tetrafluorophenyl)borate; N,N-dimethylanilinium pentafluoro phenoxytris(pentafluorophenyl)borate; N,N-diethylanilinium tetrakis(pentafluorophenyl)borate; N,N-dimethyl-2,4,6-trimethylanilinium tetrakis(pentafluorophenyl)borate; trimethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate; triethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate; tripropylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate; tri(n-butyl)ammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, dimethyl(t-butyl)ammonium tetrakis(2,3,4,6-tetra fluorophenyl)borate; N,N-dimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate; N,N-diethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate; and N,N-dimethyl-2,4,6-trimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl) borate; dialkyl ammonium salts such as: di-(i-propyl)ammonium tetrakis(pentafluorophenyl)borate, and dicyclohexylammonium tetrakis(pentafluorophenyl)borate; tri-substituted phosphonium salts such as: triphenylphosphonium tetrakis(pentafluorophenyl)borate, tri(o-tolyl)phosphonium tetrakis(pentafluorophenyl)borate, and tri(2,6-dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate; di-substituted oxonium salts such as: diphenyloxonium tetrakis(pentafluorophenyl)borate, di(o-tolyl)oxonium tetrakis(pentafluorophenyl)borate, and di(2,6-dimethylphenyl)oxonium tetrakis(pentafluorophenyl)borate; di-substituted sulfonium salts such as: diphenylsulfonium tetrakis(pentafluorophenyl)borate, di(o-tolyl)sulfonium tetrakis(pentafluorophenyl)borate, and bis(2,6-dimethylphenyl)sulfonium tetrakis(pentafluorophenyl)borate.

Another suitable ion forming, activating cocatalyst comprises a salt of a cationic oxidizing agent and a non-coordinating, compatible anion represented by the formula:
(Ox^e+)_d(A^d−)_e  Formula IX
wherein: Ox^e+ is a cationic oxidizing agent having a charge of e+; e is an integer from 1 to 3; and A^d− and d are as previously defined.

Examples of cationic oxidizing agents include, but are not limited to, ferrocenium, hydrocarbyl-substituted ferrocenium, Ag⁺, or Pb⁺². Preferred embodiments of A^d− are those anions previously defined with respect to the Bronsted acid containing activating cocatalysts, especially tetrakis(pentafluorophenyl)borate.

Another suitable ion forming, activating cocatalyst comprises a compound which is a salt of a carbenium ion and a non-coordinating, compatible anion represented by the formula: ©⁺ A⁻, wherein ©⁺ is a C_1-20 carbenium ion; and A⁻ is as previously defined. A preferred carbenium ion is the trityl cation, that is triphenylmethylium.

A further suitable ion forming, activating cocatalyst comprises a compound which is a salt of a silylium ion and a non-coordinating, compatible anion represented by the formula:
R₃Si(X′)_q⁺A⁻  Formula X

wherein: R is C_1-10 hydrocarbyl, and X′, q and A⁻ are as previously defined.

Preferred silylium salt activating cocatalysts include, but are not limited to, trimethylsilylium tetrakispentafluorophenylborate, triethylsilylium tetrakispentafluorophenylborate and ether substituted adducts thereof. Silylium salts have been previously generically disclosed in J. Chem. Soc. Chem. Comm., 1993, 383-384, as well as Lambert, J. B., et al., Organometallics, 1994, 13, 2430-2443. The use of the above silylium salts as activating cocatalysts for addition polymerization catalysts is disclosed in U.S. Pat. No. 5,625,087, which is incorporated by reference herein in its entirety. Certain complexes of alcohols, mercaptans, silanols, and oximes with tris(pentafluorophenyl)borane are also effective catalyst activators and may be used in embodiments of the invention. Such cocatalysts are disclosed in U.S. Pat. No. 5,296,433, which is also incorporated by reference herein in its entirety.

The catalyst system may be prepared as a homogeneous catalyst by addition of the requisite components to a solvent in which polymerization will be carried out by solution polymerization procedures. The catalyst system may also be prepared and employed as a heterogeneous catalyst by adsorbing the requisite components on a catalyst support material such as silica gel, alumina or other suitable inorganic support material. When prepared in heterogeneous or supported form, it is preferred to use silica as the support material. The heterogeneous form of the catalyst system may be employed in a slurry polymerization. As a practical limitation, slurry polymerization takes place in liquid diluents in which the polymer product is substantially insoluble. Preferably, the diluent for slurry polymerization is one or more hydrocarbons with less than 5 carbon atoms. If desired, saturated hydrocarbons such as ethane, propane or butane may be used in whole or in part as the diluent. Likewise the α-olefin monomer or a mixture of different α-olefin monomers may be used in whole or part as the diluent. Most preferably, the major part of the diluent comprises at least the α-olefin monomer or monomers to be polymerized.

At all times, the individual ingredients, as well as the catalyst components, should be protected from oxygen and moisture. Therefore, the catalyst components and catalysts should be prepared and recovered in an oxygen and moisture free atmosphere. Preferably, therefore, the reactions are performed in the presence of a dry, inert gas such as, for example, nitrogen or argon.

The amount of long chain branching can be influenced by the catalyst selection as well as the specifics of the process conditions used in the novel process described herein. The amount of long chain branching (in terms of LCB per 1000 carbon atoms of the polymer) generally increases with higher levels of vinyl-terminated polymer chains. Because different catalysts exhibit different levels of vinyl termination relative to other forms of termination, a catalyst having a higher level of vinyl termination preferably should be selected in order to increase the amount of long-chain branching. Preferably, the ratio, R_v, of vinyl terminated chains to the sum of all of the thermally-induced unsaturated chain ends (for example, vinyl+vinylidene+cis+trans for an ethylene/alpha olefin copolymer) should be as high as possible.

The R_v ratio is defined by the equation:

$R_v=\frac{\text{[vinyl]}}{\text{[vinyl] + [vinylidene] + [cis] + [trans]}}$
wherein [vinyl] is the concentration of vinyl groups in the isolated polymer in vinyls/1,000 carbon atoms; [vinylidene], [cis], and [trans] are the concentration of vinylidene, cis and trans groups in the isolated polymer in amount/1,000 carbon atoms, respectively. The determination of unsaturated chain ends can be accomplished by methods which are known in the art, including preferably NMR spectroscopy, particularly ¹³C NMR spectroscopy, and most preferably ¹H NMR spectroscopy. An example of the use of ¹H NMR spectroscopy to quantify unsaturated chain ends in ethylene/alpha olefin copolymers is given in Hasegawa, et al. (J. Poly. Sci., Part A, Vol 38 (2000), pages 4641-4648), the disclosure of which is incorporated herein by reference.

In order to obtain a polymer product with relatively higher levels of LCB, catalysts preferably should be chosen that produce high levels of vinyl terminated chains. Preferably, the ratio of the vinyl groups to the sum of all of the terminal unsaturations, R_v, is relatively high. In some embodiments, 5 to about 50 of the polymer chains are vinyl terminated. Other suitable catalysts may produce greater or fewer numbers of vinyl groups.

In one aspect of this invention, for ethylene homopolymers produced using more than one catalyst in a single reactor, R_v is ≧0.14 for each catalyst; preferably, R_v is ≧0.17; more preferably R_v is ≧0.19; most preferably R_v is ≧0.21. For ethylene interpolymers having a density of ≧0.920 g/mL produced using more than one catalyst in a single reactor, R_v is ≧0.13 for each catalyst; preferably, R_v is ≧0.15, more preferably R_v is ≧0.17, most preferably R_v is ≧0.19. For ethylene interpolymers having a density greater than or equal to 0.900 g/mL but less than 0.920 g/mL produced using more than one catalyst in a single reactor, R_v is ≧0.12 for each catalyst; preferably, R_v is ≧0.14; more preferably R_v is ≧0.16; most preferably R_v is ≧0.18. For ethylene interpolymers having a density greater than or equal to 0.880 g/mL but less than 0.900 g/mL produced using more than one catalyst in a single reactor, R_v is ≧0.10 for each catalyst; preferably, R_v is ≧0.12; more preferably R_v is ≧0.14; most preferably R_v is ≧0.16. For ethylene interpolymers having a density less than 0.880 g/mL produced using more than one catalyst in a single reactor, R_v is ≧0.08 for each catalyst; preferably, R_v is ≧0.10; more preferably R_v is ≧0.12; most preferably R_v is ≧0.16.

In some embodiments of the invention, R_v for one or both of the catalysts is substantially higher. Some catalysts have R_v values of about 0.25, about 0.30, about 0.35 or about 0.40. Other catalysts are characterized by an R_v of equal to or greater that about 0.50, about 0.60, or about 0.75.

In some embodiments, the catalyst pairs are selected to give substantially equal amounts of long chain branching in the HMW component and the LMW component. Thus, the ratio R_v^L/R_v^H may be greater or less than 1. Preferably, the R_v^L/R_v^H ratio ranges from 0.5 to about 2.0. In some embodiments, the R_v^L/R_v^H ratio is about 0.60, 0.70, 0.80 or 0.90. In other embodiments, the ratio is about 1.00, about 1.20, about 1.30 or about 1.40. In still other embodiments, R_v^L/R_v^H is about 1.5, about 1.6, about 1.7, about 1.8 or about 1.9. Catalyst pairs in which the low molecular weight catalyst has an R_v value that is higher than the R_v of the high molecular weight catalyst may be desirable for producing polymers having increased branching in the LMW component of the polymer composition.

Catalyst pairs may be selected by applying the following criteria. The vinyl generation, comonomer incorporation, and relative molecular weight response is determined for each catalyst by analysis according to General Procedure for Determining R_v and Comonomer Incorporation, described below. For the low molecular weight catalyst, a R_v greater than about 0.2, about 0.3, about 0.4 or about 0.5 is useful. The high molecular weight catalyst is selected according to two criteria. First, the mole % I-octene incorporation under the conditions of the test should be greater than 2%, preferably greater than 2.5%. In some embodiments, the 1-octene incorporation may be greater than about 3.0%, greater than about 4.0%, or greater than 5.0%. The incorporation of long chain branches is generally better for catalysts that can incorporate higher amounts of alpha olefins. The second criteria is based on the molecular weight of the polymer produced by the low molecular weight catalyst. The high molecular weight catalyst should produce a polymer with a M_w, as determined by the experiment described in Example 20, greater than about two times the M_w of the polymer produced by the low molecular weight catalyst.

The molar ratio of catalyst/cocatalyst employed preferably ranges from 1:10,000 to 100:1, more preferably from 1:5000 to 10:1, most preferably from 1:1000 to 1:1. Alumoxane, when used by itself as an activating cocatalyst, is generally employed in large quantity, generally at least 100 times the quantity of metal complex on a molar basis. Tris(pentafluorophenyl)borane and tris(pentafluorophenyl)aluminum, where used as an activating cocatalyst are preferably employed in a molar ratio to the metal complex of from 0.5:1 to 10:1, more preferably from 1:1 to 6:1 most preferably from 1:1 to 5:1. The remaining activating cocatalysts are generally employed in approximately equimolar quantity with the metal complex.

In general, the polymerization may be accomplished at conditions known in the art for Ziegler-Natta or Kaminsky-Sinn type polymerization reactions, that is, temperatures from −50 to 250° C., preferably 30 to 200° C. and pressures from atmospheric to 10,000 atmospheres. Suspension, solution, slurry, gas phase, solid state powder polymerization or other process condition may be employed if desired. A support, especially silica, alumina, or a polymer (especially polytetrafluoroethylene or a polyolefin) may be employed, and desirably is employed when the catalysts are used in a gas phase or slurry polymerization process. Preferably, the support is passivated before the addition of the catalyst. Passivation techniques are known in the art, and include treatment of the support with a passivating agent such as triethylaluminum. The support is preferably employed in an amount to provide a weight ratio of catalyst (based on metal):support from about 1:100,000 to about 1:10, more preferably from about 1:50,000 to about 1:20, and most preferably from about 1:10,000 to about 1:30. In most polymerization reactions, the molar ratio of catalyst:polymerizable compounds employed preferably is from about 10⁻¹²:1 to about 10⁻¹:1, more preferably from about 10⁻⁹:1 to about 10⁻⁵:1.

Suitable solvents for polymerization are inert liquids. Examples include, but are not limited to, straight and branched-chain hydrocarbons such as isobutane, butane, pentane, hexane, heptane, octane, and mixtures thereof, mixed aliphatic hydrocarbon solvents such as kerosene and ISOPAR (available from Exxon Chemicals), cyclic and alicyclic hydrocarbons such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, and mixtures thereof; perfluorinated hydrocarbons such as perfluorinated C_4-10 alkanes, and the like, and aromatic and alkyl-substituted aromatic compounds such as benzene, toluene, xylene, ethylbenzene and the like. Suitable solvents also include, but are not limited to, liquid olefins which may act as monomers or comonomers including ethylene, propylene, butadiene, cyclopentene, 1-hexene, 1-hexane, 4-vinylcyclohexene, vinylcyclohexane, 3-methyl-1-pentene, 4-methyl-1-pentene, 1,4-hexadiene, 1-octene, 1-decene, styrene, divinylbenzene, allylbenzene, vinyltoluene (including all isomers alone or in admixture), and the like. Mixtures of the foregoing are also suitable.

The catalysts may be utilized in combination with at least one additional homogeneous or heterogeneous polymerization catalyst in separate reactors connected in series or in parallel to prepare polymer blends having desirable properties. An example of such a process is disclosed in WO 94/00500, equivalent to U.S. Ser. No. 07/904,770, as well as U.S. Ser. No. 08/10,958, filed Jan. 29, 1993. The disclosures of the patent applications are incorporated by references herein in their entirety.

The catalyst system may be prepared as a homogeneous catalyst by addition of the requisite components to a solvent in which polymerization will be carried out by solution polymerization procedures. The catalyst system may also be prepared and employed as a heterogeneous catalyst by adsorbing the requisite components on a catalyst support material such as silica gel, alumina or other suitable inorganic support material. When prepared in heterogeneous or supported form, it is preferred to use silica as the support material. The heterogeneous form of the catalyst system may be employed in a slurry polymerization. As a practical limitation, slurry polymerization takes place in liquid diluents in which the polymer product is substantially insoluble. Preferably, the diluent for slurry polymerization is one or more hydrocarbons with less than 5 carbon atoms. If desired, saturated hydrocarbons such as ethane, propane or butane may be used in whole or in part as the diluent. Likewise the α-olefin monomer or a mixture of different α-olefin monomers may be used in whole or part as the diluent. Most preferably, the major part of the diluent comprises at least the α-olefin monomer or monomers to be polymerized.

Solution polymerization conditions utilize a solvent for the respective components of the reaction. Preferred solvents include, but are not limited to, mineral oils and the various hydrocarbons which are liquid at reaction temperatures and pressures. Illustrative examples of useful solvents include, but are not limited to, alkanes such as pentane, iso-pentane, hexane, heptane, octane and nonane, as well as mixtures of alkanes including kerosene and Isopar E™, available from Exxon Chemicals Inc.; cycloalkanes such as cyclopentane, cyclohexane, and methylcyclohexane; and aromatics such as benzene, toluene, xylenes, ethylbenzene and diethylbenzene.

The polymerization may be carried out as a batch or a continuous polymerization process. A continuous process is preferred, in which event catalysts, solvent or diluent (if employed), and comonomers (or monomer) are continuously supplied to the reaction zone and polymer product continuously removed therefrom. The polymerization conditions for manufacturing the interpolymers according to embodiments of the invention are generally those useful in the solution polymerization process, although the application is not limited thereto. Gas phase and slurry polymerization processes are also believed to be useful, provided the proper catalysts and polymerization conditions are employed.

In some embodiments, the polymerization is conducted in a continuous solution polymerization system comprising two reactors connected in series or parallel. One or both reactors contain at least two catalysts which have a substantially similar comonomer incorporation capability but different molecular weight capability. In one reactor, a relatively high molecular weight product (M_w from 100,000 to over 1,000,000, more preferably 200,000 to 1,000,000) is formed while in the second reactor a product of a relatively low molecular weight (M_w 2,000 to 300,000) is formed. The final product is a mixture of the reactor effluents which are combined prior to devolatilization to result in a uniform mixing of the two polymer products. Such a dual reactor/dual catalyst process allows for the preparation of products with tailored properties. In one embodiment, the reactors are connected in series, that is the effluent from the first reactor is charged to the second reactor and fresh monomer, solvent and hydrogen is added to the second reactor. Reactor conditions are adjusted such that the weight ratio of polymer produced in the first reactor to that produced in the second reactor is from 20:80 to 80:20. In addition, the temperature of the second reactor is controlled to produce the lower molecular weight product. In one embodiment, the second reactor in a series polymerization process contains a heterogeneous Ziegler-Natta catalyst or chrome catalyst known in the art. Examples of Ziegler-Natta catalysts include, but are not limited to, titanium-based catalysts supported on MgCl₂, and additionally comprise compounds of aluminum containing at least one aluminum-alkyl bond. Suitable Ziegler-Natta catalysts and their preparation include, but are not limited to, those disclosed in U.S. Pat. No. 4,612,300, U.S. Pat. No. 4,330,646, and U.S. Pat. No. 5,869,575. The disclosures of each of these three patents are herein incorporated by reference.

In some embodiments, ethylene is added to the reaction vessel in an amount to maintain a differential pressure in excess of the combined vapor pressure of the α-olefin and diene monomers. The ethylene content of the polymer is determined by the ratio of ethylene differential pressure to the total reactor pressure. Generally the polymerization process is carried out with a pressure of ethylene of from 10 to 1000 psi (70 to 7000 kPa), most preferably from 40 to 800 psi (30 to 600 kPa). The polymerization is generally conducted at a temperature of from 25 to 250° C., preferably from 75 to 200° C., and most preferably from greater than 95 to 200° C.

The optional cocatalysts and scavenger components in the novel process can be independently mixed with each catalyst component before the catalyst components are introduced into the reactor, or they may each independently be fed into the reactor using separate streams, resulting in “in reactor” activation. Scavenger components are known in the art and include, but are not limited to, alkyl aluminum compounds, including alumoxanes. Examples of scavengers include, but are not limited to, trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, trioctyl aluminum, methylalumoxane (MAO), and other alumoxanes including, but not limited to, MMAO-3A, MMAO-7, PMAO-IP (all available from Akzo Nobel).

For the novel processes described herein, the polymer properties can be tailored by adjustment of process conditions. Process conditions generally refer to temperature, pressure, monomer content (including comonomer concentration), catalyst concentration, cocatalyst concentration, activator concentration, etc., that influence the molecular weight or branching of the polymer produced. In general, for ethylene based polymers, the amount of long chain branching increases with a decrease in the concentration of ethylene. Thus, particularly in solution polymerization, the amount of long-chain branching can be controlled by adjusting the ethylene concentration, reactor temperature, and polymer concentration. In general, higher reactor temperatures lead to a higher level of polymer molecules that have unsaturated end groups. Long chain branching can be increased by selecting catalysts that generate a relatively large percentage of vinyl end groups, selecting catalysts having relatively high comonomer incorporating ability (i.e., low r₁), operating at relatively high reactor temperature at low ethylene and comonomer concentration, and high polymer concentration. By proper selection of process conditions, including catalyst selection, polymers with tailored properties can be produced. For a solution polymerization process, especially a continuous solution polymerization, preferred ranges of ethylene concentration at steady state are from about 0.25 weight percent of the total reactor contents to about 5 weight percent of the total reactor contents, and the preferred range of polymer concentration is from about 10% of the reactor contents by weight to about 45% of the reactor contents or higher.

Applications:

The polymers made in accordance with embodiments of the invention have many useful applications. For example, fabricated articles made from the polymers may be prepared using all of the conventional polyolefin processing techniques. Useful articles include films (e.g., cast, blown and extrusion coated), including multi-layer films, fibers (e.g., staple fibers) including use of an interpolymer disclosed herein as at least one component comprising at least a portion of the fiber's surface, spunbond fibers or melt blown fibers (using, e.g., systems as disclosed in U.S. Pat. No. 4,430,563, U.S. Pat. No. 4,663,220, U.S. Pat. No. 4,668,566, or U.S. Pat. No. 4,322,027, all of which are incorporated herein by reference), and gel spun fibers (e.g., the system disclosed in U.S. Pat. No. 4,413,110, incorporated herein by reference), both woven and nonwoven fabrics (e.g., spun-laced fabrics disclosed in U.S. Pat. No. 3,485,706, incorporated herein by reference) or structures made from such fibers (including, e.g., blends of these fibers with other fibers, e.g., PET or cotton) and molded articles (e.g., made using an injection molding process, a blow molding process or a rotomolding process). Monolayer and multilayer films may be made according to the film structures and fabrication methods described in U.S. Pat. No. 5,685,128, which is incorporated by reference herein in its entirety. The polymers described herein are also useful for wire and cable coating operations, as well as in sheet extrusion for vacuum forming operations.

Specific applications wherein the inventive polymers disclosed herein may be used include, but are not limited to, greenhouse films, shrink film, clarity shrink film, lamination film, extrusion coating, liners, clarity liners, overwrap film, agricultural film, high strength foam, soft foam, rigid foam, cross-linked foam, high strength foam for cushioning applications, sound insulation foam, blow molded bottles, wire and cable jacketing, including medium and high voltage cable jacketing, wire and cable insulation, especially medium and high voltage cable insulation, telecommunications cable jackets, optical fiber jackets, pipes, and frozen food packages. Some such uses are disclosed in U.S. Pat. No. 6,325,956, incorporated here by reference in its entirety. Additionally, the polymers disclosed herein may replace one or more of those used in the compositions and structures described in U.S. Pat. No. 6,270,856, U.S. Pat. No. 5,674,613, U.S. Pat. No. 5,462,807, U.S. Pat. No. 5,246,783, and U.S. Pat. No. 4,508,771, each of which is incorporated herein by reference in its entirety. The skilled artisan will appreciate other uses for the novel polymers and compositions disclosed herein.

Useful compositions are also suitably prepared comprising the polymers according to embodiments of the invention and at least one other natural or synthetic polymer. Preferred other polymers include, but are not limited to, thermoplastics, such as styrene-butadiene block copolymers, polystyrene (including high impact polystyrene), ethylene vinyl alcohol copolymers, ethylene vinyl acetate copolymers, ethylene acrylic acid copolymers, other olefin copolymers (especially polyethylene copolymers) and homopolymers (e.g., those made using conventional heterogeneous catalysts). Examples include polymers made by the process of U.S. Pat. No. 4,076,698, incorporated herein by reference, other linear or substantially linear polymers as described in U.S. Pat. No. 5,272,236, and mixtures thereof. Other substantially linear polymers and conventional HDPE and/or LDPE may also be used in the thermoplastic compositions.

EXAMPLES

The following examples are given to illustrate various embodiments of the invention. They do not intend to limit the invention as otherwise described and claimed herein. All numerical values are approximate. When a numerical range is given, it should be understood that embodiments outside the range are still within the scope of the invention unless otherwise indicated. In the following examples, various polymers were characterized by a number of methods. Performance data of these polymers were also obtained. Most of the methods or tests were performed in accordance with an ASTM standard, if applicable, or known procedures.

Unless indicated otherwise, the following testing procedures are to be employed:

Density is measured in accordance with ASTM D-792. The samples are annealed at ambient conditions for 24 hours before the measurement is taken.

The molecular weight of polyolefin polymers is conveniently indicated using a melt index measurement according to ASTM D-1238, Condition 190° C./2.16 kg (formerly known as “Condition E” and also known as I₂). Melt index is inversely proportional to the molecular weight of the polymer. Thus, the higher the molecular weight, the lower the melt index, although the relationship is not linear. The overall 12 melt index of the novel composition is in the range of from 0.01 to 1000 g/10 minutes. Other measurements useful in characterizing the molecular weight of ethylene interpolymer compositions involve melt index determinations with higher weights, such as, for common example, ASTM D-1238, Condition 190° C./10 kg (formerly known as “Condition N” and also known as I₁₀). The ratio of a higher weight melt index determination to a lower weight determination is known as a melt flow ratio, and for measured I₁₀ and the I₂ melt index values the melt flow ratio is conveniently designated as I₁₀/I₂.

Gel Permeation Chromatography (GPC) data were generated using either a Waters 150C/ALC, a Polymer Laboratories Model PL-210 or a Polymer Laboratories Model PL-220. The column and carousel compartments were operated at 140° C. The columns used were 3 Polymer Laboratories 10 micron Mixed-B columns. The samples were prepared at a concentration of 0.1 grams of polymer in 50 milliliters of 1,2,4 trichlorobenzene. The 1,2,4 trichlorobenzene used to prepare the samples contained 200 ppm of butylated hydroxytoluene (BHT). Samples were prepared by agitating lightly for 2 hours at 160° C. The injection volume used was 100 microliters and the flow rate was 1.0 milliliters/minute. Calibration of the GPC was performed with narrow molecular weight distribution polystyrene standards purchased from Polymer Laboratories. These polystyrene standard peak molecular weights were converted to polyethylene molecular weights using the following equation (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968).:
M_polyethylene=Ax(M_polystyrene)^B
where M is the molecular weight, A has a value of 0.4316 and B is equal to 1.0. The molecular weight calculations were performed with the Viscotek TriSEC software.

The GPC data were then deconvoluted to give the most probable fit for two molecular weight components. There are a number of deconvolution algorithms available both commercially and in the literature. These may lead to different answers depending upon the assumptions used. The algorithm summarized here is optimized for the deconvolution problem of the two most probable molecular weight distributions (plus an adjustable error term). In order to allow for the variations in the underlying distributions due to the macromer incorporation and small fluctuations in the reactor conditions (i.e. temperature, concentration) the basis functions were modified to incorporate a normal distribution term. This term allows the basis function for each component to be “smeared” to varying degrees along the molecular weight axis. The advantage is that in the limit (low LCB, perfect concentration and temperature control) the basis function will become a simple, most probable, Flory distribution.

Three components (j=1,2,3) are derived with the third component (j=3) being an adjustable error term. The GPC data must be normalized and properly transformed into weight fraction versus Log₁₀ molecular weight vectors. In other words, each potential curve for deconvolution should consist of a height vector, h_i, where the heights are reported at known intervals of Log₁₀ molecular weight, the h_i have been properly transformed from the elution volume domain to the Log₁₀ molecular weight domain, and the h_i are normalized. Additionally, these data should be made available for the Microsoft EXCEL™ application.

Several assumption are made in the deconvolution. Each component, j, consists of a most probable, Flory, distribution which has been convoluted with a normal or Gaussian spreading function using a parameter, σ_j. The resulting, three basis functions are used in a Chi-square, X², minimization routine to locate the parameters that best fit the n points in h_i, the GPC data vector.

$X^2\left({\mu }_j,{\sigma }_j,w_j\right)=\underset{i=1}{\sum ^n}{\left[\underset{j=1}{\sum ^3}·\underset{k=1}{\sum ^{20}}{w}_j·M_i^2·{\lambda }_{j,k}^2·{\mathrm{CumND}}_{j,k}·e^{-{\lambda }_{j,k}·M_i}·\Delta {\mathrm{Log}}_{10}M-h_i\right]}^2$ ${\lambda }_{j,k}={10}^{\mu j+\frac{k-10}{3}·{\sigma }_j}$
The variable, CumND_j,k, is calculated using the EXCEL™ function “NORMDIST (x, mean, standard_dev, cumulative)” with the parameters set as follows:
x=μ_j+(k−10)*σ_j/3
mean=μ_j
standard dev=σ_j
cumulative=TRUE

Table I below summarizes these variables and their definitions. The use of the EXCEL™ software application, Solver, is adequate for this task. Constraints are added to Solver insure proper minimization.

TABLE I

Variable Definitions
Variable
Name    Definition

λj,k    Reciprocal of the number average molecular weight
        of most probable (Flory) distribution for component j,
        normal distribution slice k
σj      Sigma (square root of variance) for normal (Gaussian)
        spreading function for component j.
wj      Weight fraction of component j
K       Normalization term (1.0/Loge 10)
Mi      Molecular weight at elution volume slice i
hi      Height of log10 (molecular weight) plot at slice i
n       Number of slices in Log molecular weight plot
i       Log molecular weight slice index (1 to n)
j       Component index (1 to 3)
1. k    Normal distribution slice index
Δlog10M Average difference between log10Mi and log10Mi−1 in height
        vs. log10M plot

The 8 parameters that are derived from the Chi-square minimization are μ₁, μ₂, μ₃, σ₁, σ₂, σ₃, w₁, and w₂. The term w₃ is subsequently derived from w, and w₂ since the sum of the 3 components must equal 1. Table II is a summary of the Solver constraints used in the EXCEL program.

TABLE II

Constraint summary
Description                      Constraint

Maximum of fraction 1            w1 < 0.95 (User adjustable)
Lower limit of spreading function σ1, σ2, σ3 > 0.001 (must be positive)
Upper limit of spreading function σ1, σ2, σ3 < 0.2 (User adjustable)
Normalized fractions             w1 + w2 + w3 = 1.0

Additional constraints that are to be understood include the limitation that only μ_j>0 are allowed, although if solver is properly initialized, this constraint need not be entered, as the solver routine will not move any of the μ_j to values less than about 0.005. Also, the w_j are all understood to be positive. This constraint can be handled outside of solver. If the w_j are understood to arise from the selection of two points along the interval 0.0<P₁<P₂<1.0; whereby w₁=P₁, w₂=P₂−P₁ and w₃=1.0−P₂; then constraining P1and P2are equivalent to the constraints required above for the w_j.

Table III is a summary of the Solver settings under the Options tab.

TABLE III

Solver settings
Label                Value or selection

Max Time (seconds)   1000
Iterations           100
Precision            0.000001
Tolerance (%)        5
Convergence          0.001
Estimates            Tangent
Derivatives          Forward
Search               Newton
ALL OTHER SELECTIONS Not selected

A first guess for the values of μ₁, μ₂, w₁, and w₂ can be obtained by assuming two ideal Flory components that give the observed weight average, number average, and z-average molecular weights for the observed GPC distribution.

$M_{n,\mathrm{GPC}}={\left[w_1·\frac{1}{{10}^{{\mu }_1}}+w_2·\frac{1}{{10}^{{\mu }_2}}\right]}^{-1}$ $M_{w,\mathrm{GPC}}=\frac{\left[w_1·2·{10}^{{\mu }_1}+w_2·2·{10}^{{\mu }_2}\right]}{M_{n,\mathrm{GPC}}}$ $M_{z,\mathrm{GPC}}=\frac{\left[w_1·6·{10}^{{\mu }_1}+w_2·6·{10}^{{\mu }_2}\right]}{M_{w,\mathrm{GPC}}}$ $w_1+w_2=1$
The values of μ₁, μ₂, w₁, and w₂ are then calculated. These should be adjusted carefully to allow for a small error term, w₃, and to meet the constraints in Table II before entering into Solver for the minimization step. Starting values for σ_j are all set to 0.05.

Preparative GPC for collecting selected fractions of polymers was performed on a Waters 150C/ALC equipped with preparative pump heads and modified with a 3000 microliter injection loop and 14 milliliter sample vials. The column and carousel compartments were operated at 140° C. The preparative GPC column used was 1 Jordi Associaties 5 micron divinylbenzene (DVB) column catalog number 15105. The column dimensions were 500 mm in length and 22 mm inner diameter. 1,2,4 trichlorobenzene was used for both sample preparation and as the chromatographic mobile phase. The samples were prepared at a concentration of 0.1 grams of polymer in 50 milliliters of solvent. The solvent used to prepare the samples contained 200 ppm of butylated hydroxytoluene (BHT). Samples were prepared by agitating lightly for 2 hours at 160° C. The injection volume used was 2,500 microliters and the flow rate was 5.0 milliliters/minute.

Approximately 200-300 injections were made to collect appropriate sample amounts for off-line analysis. 16 fractions were collected spanning the full column elution range, with 8-12 fractions typically spanning the sample elution range. Elution range was verified by refractive index analysis during start-up. The collected solvent fractions were evaporated to approximately 50-60 milliliter volumes with a Buchi Rotovapor R-205 unit equipped with a vacuum controller module V-805 and a heating bath module B-409. The fractions were then allowed to cool to room temperature and the polyethylene material was precipitated by adding approximately 200 milliliters of methanol. Verification of molecular weight fractionation was done via high temperature GPC analysis with refractive index detection. Typical polydispersities of the fractions as measured by GPC analysis were approximately 1.1 to 1.4.

The weight average branching index for selected fractions was obtained from direct determination of intrinsic viscosity and molecular weight at each chromatographic data slice. The chromatographic system consisted of either a Polymer Laboratories Model PL-210 or a Polymer Laboratories Model PL-220 equipped with a Viscotek differential viscometer Model 210R, and a Precision Detectors 2-angle laser light scattering detector Model 2040. The 15-degree angle of the light scattering detector was used for the calculation of molecular weights.

The column and carousel compartments were operated at 140° C. The columns used were 3 Polymer Laboratories 10-micron Mixed-B columns. The solvent used was 1,2,4 trichlorobenzene. The samples were prepared at a concentration of 0.1 grams of polymer in 50 milliliters of solvent. The solvent used to prepare the samples contained 200 ppm of butylated hydroxytoluene (BHT). Samples were prepared by agitating lightly for 2 hours at 160° C. The injection volume used was 100 microliters and the flow rate was 1.0 milliliters/minute.

Calibration of the GPC column set was performed with narrow molecular weight distribution polystyrene standards purchased from Polymer Laboratories. The calibration of the detectors was performed in a manner traceable to NBS 1475 using a linear polyethylene homopolymer. ¹³C NMR was used to verify the linearity and composition of the homopolymer standard. The refractometer was calibrated for mass verification purposes based on the known concentration and injection volume. The viscometer was calibrated with NBS 1475 using a value of 1.01 deciliters/gram and the light scattering detector was calibrated using NBS 1475 using a molecular weight of 52,000 Daltons.

The Systematic Approach for the determination of multidetector offsets was done in a manner consistent with that published by Mourey and Balke, Chromatography of Polymers: T. Provder, Ed.; ACS Symposium Series 521; American Chemical Society: Washington, D.C., (1993) pp 180-198 and Balke, et al., ; T. Provder, Ed.; ACS Symposium Series 521; American Chemical Society: Washington, D.C., (1993): pp 199-219., both of which are incorporated herein by reference in their entirety. The triple detector results were compared with polystyrene standard reference material NBS 706 (National Bureau of Standards), or DOW chemical polystyrene resin 1683 to the polystyrene column calibration results from the polystyrene narrow standards calibration curve.

Verification of detector alignment and calibration was made by analyzing a linear polyethylene homopolymer with a polydispersity of approximately 3 and a molecular weight of 115,000. The slope of the resultant Mark-Houwink plot of the linear homopolymer was verified to be within the range of 0.725 to 0.730 between 30,000 and 600,000 molecular weight. The verification procedure included analyzing a minimum of 3 injections to ensure reliability. The polystyrene standard peak molecular weights were converted to polyethylene molecular weights using the method of Williams and Ward described previously. The agreement for M_w and M_n between the polystyrene calibration method and the absolute triple detector method were verified to be within 5% for the polyethylene homopolymer.

The intrinsic viscosity data was obtained in a manner consistent with the Haney 4-capillary viscometer described in U.S. Pat. No. 4,463,598, incorporated herein by reference. The molecular weight data was obtained in a manner consistent with that published by Zimm (Zimm, B. H., J. Chem. Phys., 16, 1099 (1948)) and Kratochvil (Kratochvil, P., Classical Light Scattering from Polymer Solutions, Elsevier, Oxford, N.Y. (1987)). The overall injected concentration used for the determination of the intrinsic viscosity and molecular weight were obtained from the sample refractive index area and the refractive index detector calibration from the linear polyethylene homopolymer and all samples were found to be within experimental error of the nominal concentration. The chromatographic concentrations were assumed low enough to eliminate the need for a Huggin's constant (concentration effects on intrinsic viscosity) and second virial coefficient effects (concentration effects on molecular weight).

For samples that contain comonomer, the measured g′ represents effects of both long chain branching as well as short chain branching due to comonomer. For samples that have copolymer component(s), the contribution from short chain branching structure should be removed as taught in Scholte et al., discussed above. If the comonomer is incorporated in such a manner that the short chain branching structure is proven both equivalent and constant across both the low and high molecular weight components, then the difference in long chain branching index between 100,000 and 500,000 may be directly calculated from the copolymer sample. For cases where the comonomer incorporation cannot be proven both equivalent and constant across both the high and low molecular weight components, then preparative GPC fractionation is required in order to isolate narrow molecular weight fractions with polydispersity lower than 1.4. ¹³C NMR is used to determine the comonomer content of the preparative fractions.

Additionally, a calibration of g′ against comonomer type for a series of linear copolymers of the same comonomer is established in order to correct for comonomer content, in cases where comonomer incorporation cannot be shown to be both equivalent and constant across both the high and low molecular weight components. The g′ value is then analyzed for the isolated fraction corresponding to the desired molecular weight region of interest and corrected via the comonomer calibration function to remove comonomer effects from g′. Estimation of number of branches per molecule on the high molecular weight species.

The number of long chain branches per molecule was also determined by GPC methods. High temperature GPC results (HTGPC) were compared with high temperature GPC light scattering results (HTGPC-LS). Such measurements can be conveniently recorded on a calibrated GPC system containing both light scattering and concentrations detectors which allows the necessary data to be collected from a single chromatographic system and injection. These measurements assume that the separation mechanism by HTGPC is due to the longest contiguous backbone segment through a polymer molecule (i.e. the backbone). Therefore, it assumes that the molecular weight obtained by HTGPC produces the backbone molecular weight (linear equivalent molecular weight) of the polymer. The average sum of the molecular weight of long chain branches added to the backbone at any chromatographic data slice is obtained by subtracting the backbone molecular weight estimate from the absolute molecular weight obtained by HTGPC-LS. If there is a significant comonomer content differential between the high and low molecular weight species in the polymer, it is necessary to subtract the weight of the comonomer from the HTGPC-LS results using knowledge of the high molecular weight catalyst.

The average molecular weight of the long chain branches that are added to the high molecular weight polymer is assumed to be equivalent to the number-average molecular weight of the bulk polymer (considering both high and low molecular weight species). Alternatively, an estimate of the average molecular weight of a long chain branch can be obtained by dividing the weight-average molecular weight of the low molecular weight species (obtained through de-convolution techniques) by a polydispersity estimate of the low molecular weight species. If there is a significant comonomer content differential between the high and low molecular weight species in the polymer, it is necessary to add or subtract the differential total weight of comonomer from the number average molecular weight results first using knowledge of the comonomer incorporation for the low molecular weight catalyst.

The number of long chain branches at any chromatographic slice is estimated by dividing the sum of the molecular weight of the total long chain branches by the average molecular weight of the long chain branch. By averaging this number of long chain branches weighted by the deconvoluted high molecular weight peak, the average amount of long chain branching for the high molecular weight species is determined. Although assumptions are made in regard to GPC separation and the fact that the polymer backbone can be extended due to a long chain branch incorporating near to the chain ends of the backbone segment, we have found this measure of number of branches to be very useful in predicting resin performance.

Melt strength measurements were conducted on a Goettfert Rheotens 71.97 attached to an Model 3211 Instron capillary rheometer. A polymer melt was extruded through a capillary die (flat die, 180 degree angle) with a capillary diameter of 2.1 mm and an aspect ratio (capillary length/capillary radius) of 20 with an entrance angle of approximately 45 degrees at a constant plunger velocity. After equilibrating the samples at 190° C. for 10 minutes, the piston is run at a speed of 1 inch/minute (2.54 cm/min). The standard test temperature is 190° C. the sample is drawn uniaxially to a set of accelerating nips located 100 mm below the die with an acceleration of 2.4 mm/s². The tensile force is recorded as a function of the take-up speed of the nip rolls. Melt strength was reported as the plateau force (cN) before the strand broke. The following conditions were used in the melt strength measurements.

• • plunger speed=0.423 mm/s
  • wheel acceleration=2.4 mm/s/s
  • capillary diameter=2.1 mm
  • capillary length=42 mm
  • barrel diameter=9.52 mm

Synthesis of (N-(1,1-dimethylethyl)-1,1-di-(4-n-butyl-phenyl)-1-((1,2,3,3a,7a-η)-3-(1,3-dihydro-2H-isoindol-2-yl)-1H-inden-1-yl)silanaminato-(2-)-N—) dimethyltitanium (Catalyst A)

(1) Preparation of dichloro(N-(1,1-dimethylethyl)-1,1-di(4-butyl-phenyl)-1-((1,2,3,3a,7a-η)-3-(1,3-dihydro-2H-isoindol-2-yl)-1H-inden-1-yl)silanaminato-(2-)-N—)-titanium

##STR00008##

[A] Synthesis of dichloro(N-1,1-dimethylethyl)-1,1-(4-butyl-phenyl)-1-((1,2,3,3a,7a-n)-3-(1,3-dihydro-2H-isoindol-2-yl)-1H-inden-1-yl)silanaminato-(2-)-N—)titanium

##STR00009##

To a three-necked 250 mL round-bottom flask under a nitrogen atmosphere equipped with a reflux condenser and a 250 mL dropping funnel 4.87 g of Mg turnings (0.200 moles) were introduced. 1-bromo-4-butyl benzene (42.62 g, 0.200 moles) and 80 mL of THF were then added to the dropping funnel. At this time 10 mL of the bromobenzene/THF solution was added to the Mg turnings with a small amount of ethyl bromide. The solution was then stirred until initiation occurred. The rest of the bromo benzene/THF solution was then added dropwise to allow refluxing to occur. After addition of the bromo benzene/THF solution, the mixture was heated at reflux until the magnesium was consumed.

The resulting Grignard solution was then transferred to a 250 mL dropping funnel which was attached to a three-necked 250 mL round-bottom flask under a nitrogen atmosphere equipped with a reflux condenser. To the round bottomed flask 100 mL of heptane was introduced followed by SiCl₄ (15.29 g, 0.090 moles). To this solution, the Grignard solution was added dropwise. After addition was complete the resulting mixture was refluxed for 2 h and then allowed to cool to room temperature. Under an inert atmosphere the solution was filtered. The remaining salts were further washed with heptane (3×40 mL), the washings were combined with the original heptane solution.

The heptane was then removed via distillation at atmospheric pressure. The resulting viscous oil was then vacuumed distilled with collection of the product at 1 mm at 210° C. giving 19.3 g (58%). ¹H(C₆D₆)δ: 0.80 (t, 6H), 1.19 (m, 4 H), 1.39 (m, 4 H), 2.35 (t, 4 H), 7.0 (d, 4H), 7.7 (d, 4H).

##STR00010##

Dichloro-di(p-butylphenyl)silane (4.572 g, 12.51 mmol) was dissolved in 45 mL of methylene chloride. To this solution was added 1.83 g, 25.03 mmol of t-BuNH₂. After stirring overnight Solvent was removed under reduced pressure. The residue was extracted with 45 mL of hexane and filtered. Solvent was removed under reduced pressure leaving 4.852 g of product as an off-white oil. ¹H(C₆D₆) δ: 0.75 (t, 6 H), 1.15 (s, 9 H), 1.2 (m, 4 H), 1.4 (m, 4 H), 1.51 (s, 1 H), 2.4 (t, 4 H), 7.05 (d, 4 H), 7.8 (d, 4 H).

##STR00011##

To a 4.612 g (11.47 mmol) of (p-Bu-Ph)₂Si(Cl)(NH-t-Bu) dissolved in 20 mL of THF was added 2.744 g (8.37 mmol) of lithium 1-isoindolino-indenide dissolved in 30 mL of THF. After the reaction mixture was stirred overnight, solvent was removed under reduced pressure. The residue was extracted with 50 mL of hexane and filtered. Solvent removal gave 6.870 g of product as very viscous red-brown oil. Yield 91.0% ¹H (C₆D₆) δ: 0.75 (m, 6 H), 1.15 (s, 9 H), 1.25 (m, 4 H), 2.4 (m, 4H), 4.2 (s, 1H), 4.5 (dd, 4 H), 5.6 (s, 1H) 6.9-7.7 (m, 16 H).

[B] Preparation of dilithium salt of (p-Bu-Ph)₂Si(3-isoindolino-indenyl)(NH-t-Bu). To a 50 mL of hexane solution containing 6.186 g (10.33 mmol) of (p-Bu-Ph)₂Si(3-isoindolino-indenyl)(NH-t-Bu) was added 13.5 mL of 1.6 M n-BuLi solution. A few minutes after n-BuLi addition a yellow precipitate appeared. After stirring overnight the yellow precipitate was collected on the frit, washed with 4×20 mL of hexane and dried under reduced pressure to give 4.4181 g of product as yellow powder. Yield 70.0%.

[C] Preparation of dichloro(N-1,1-dimethylethyl)-1,1-(4-butyl-phenyl)-1-((1,2,3,3a,7a-n)-3-(1,3-dihydro-2H-isoindol-2-yl)-1H-inden-1-yl)silanaminato-(2-)-N—)titanium

##STR00012##

In the drybox 2.620 g (7.1 mmol) of TiCl₃(THF)₃ was suspended in 40 mL of THF. To this solution 4.319 g (7.07 mmol) of dilithium salt of (p-Bu-Ph)₂Si(3-isoindolino-indenyl)(NH-t-Bu) dissolved in 60 mL of THF was added within 2 min The solution was then stirred for 60 min. After this time 1.278 g of PbCl₂ (4.60 mmol) was added and the solution was stirred for 60 min. The THF was then removed under reduced pressure. The residue was extracted with 50 mL of toluene and filtered. Solvent was removed under reduced pressure leaving black crystalline solid. Hexane was added (35 mL) and the black suspension was stirred for 0.5 hr. Solid was collected on the frit, washed with 2×30 mL of hexane and dried under reduced pressure to give 4.6754 g of product as black-blue crystalline solid. Yield 92.4%. ¹H (toluene-d₆) δ: 0.75 (m, 6 H), 1.25 (m, 4 H), 1.5 (m, 4 H), 1.65 (s, 9 H), 2.5 (t, 4 H), 4.5 (d, 2 H), 5.0 (d, 2 H), 6.0 (s, 1 H), 6.8-8.2 (m, 16 H).

(2) Preparation of (N-1,1-dimethylethyl)-1,1-(4-butyl-phenyl)-1-((1,2,3,3a,7a-n)-3-(1,3-dihydro-2H-isoindol-2-yl)-1H-inden-1-yl)silanaminato-(2-)-N—)-dimethyltitanium

##STR00013##

The dichloro(N-1,1-dimethylethyl)-1,1-(4-butyl-phenyl)-1-((1,2,3,3a,7a-n)-3-(1,3-dihydro-2H-isoindol-2-yl)-1H-inden-1-yl)silanaminato-(2-)-N—)titanium (1.608 g, 2.25 mmol) was suspended in 35 mL of toluene. To this solution was added 3 mL (4.75 mmol) of 1.6 M MeLi ether solution. Reaction color changed at once from dark green-black to dark red. After stirring for 1 hr solvent was removed under reduced pressure. The residue was extracted with 55 mL of hexane and filtered. Solvent was removed leaving 1.456 g of red solid. Yield 96%. ¹H (toluene-d₈) δ: 0.3 (s, 3 H), 0.8 (m, 6 H), 1.05 (s, 3 H), 1.25 (m, 4 H), 1.5 (m, 4 H), 1.75 (s, 9 H), 2.5 (m, 4 H), 4.5 (d, 2 H), 4.8 (d, 2 H), 5.7 (s, 1 H), 6.7-8.3 (m, 16 H).

Synthesis of rac-[1,2-ethanediylbis(1-indenyl)]zirconium (1,4-diphenyl-1,3-butadiene) (Catalyst B)

Catalyst B can be synthesized according to Example 11 of U.S. Pat. No. 5,616,664, the entire disclosure of which patent is incorporated herein by reference.

Synthesis of (C₅Me₄SiMe₂N^tBu)Ti(η⁴-1,3-pentadiene) (Catalyst C)

Catalyst C can be synthesized according to Example 17 of U.S. Pat. No. 5,556,928, the entire disclosure of which patent is incorporated herein by reference.

Synthesis of dimethylsilyl(2-methyl-s-indacenyl)(t-butylamido)titanium 1,3-pentadiene (Catalyst D)

Catalyst D can be synthesized according to Example 23 of U.S. Pat. No. 5,965,756, the entire disclosure of which patent is incorporated herein by reference.

Synthesis of [(3-Phenylindenyl)SiMe₂N^tBut]TiMe₂ (Catalyst E)

Catalyst F can be synthesized according to Example 2 of U.S. Pat. No. 5,866,704, the entire disclosure of which patent is incorporated herein by reference.

Synthesis of dimethylamidoborane-bis-η⁵-(2-methyl-4-naphthylinden-1-yl)zirconium η⁴-1,4-diphenyl-1,3-butadiene (Catalyst F)

Catalyst G can be synthesized according to Example 12 of WO 0020426, the entire disclosure of which patent is incorporated herein by reference.

Synthesis of (N-(1,1-dimethylethyl)-1,1-dimethyl-1-((1,2,3,3a,9a,-h)-5,6,7,8-tetrahydro-3-phenyl-5,5,8,8-tetramethyl-1H-benz(f)inden-1-yl)silanaminato(2-) N)dimethyltitanium (Catalyst G)

Catalyst H can be synthesized according to Example 13 of WO 9827103, the entire disclosure of which patent is incorporated herein by reference.

Synthesis of bis(n-butylcyclopentadienyl)zirconium dimethyl (Catalyst H)

Bis(n-butylcyclopentadienylzirconium dichloride can be purchased from Boulder Scientific. In a drybox, 12.00 g of bis(n-butylcyclopentadienylzirconium dichloride was dissolved in 100 mL of diethyl ether in an 8 oz jar. 20.765 mL of 3.0 M methyl magnesium chloride in THF (available from Aldrich Chemical Company) was added dropwise via syringe with stirring. After stirring for 30 minutes, the volatiles were removed under vacuum. The residue was extracted with hexane, and filtered through Celite. The hexane was stripped under vacuum to afford a brown liquid, which was identified by ¹H and ¹³C NMR spectroscopy. The yield was 7.6 g.

Synthesis of meso-[dimethylsilylbis(1-indenyl)]hafnium dimethyl (Catalyst I)

The meso dimethyl hafnium compound can be obtained from the racemic hafnium dichloride according to the following procedure. Rac-dimethylsilylbis(indenyl)hafnium dichloride was purchased from Boulder Scientific Co. In an inert atmosphere drybox, 1.002 g of rac-dimethylsilylbis(indenyl)hafnium dichloride was dissolved in approximately 30 mL of dry THF. To this solution was added with stirring 1.3 mL of CH₃MgCl (3.0 M in THF, Aldrich) via syringe. The solution turned slightly darker and was allowed to stir at room temperature for 45 minutes. The THF was subsequently removed under vacuum. The residue was dissolved in hot methylcyclohexane, filtered through Celite, and cooled. Small crystals immediately formed upon cooling. The solution was re-warmed, and allowed to cool slowly. The crystalline product was collected by filtration and characterized by ¹H and ¹³C NMR spectroscopy, as well as single-crystal X-ray diffraction.

Synthesis of Armeenium Borate [methylbis(hydrogenatedtallowalkyl)ammonium tetrakis (pentafluoro phenyl)borate]

Armeenium borate can be prepared from ARMEEN® M2HT (available from Akzo-Nobel), HCl, and Li [B(C₆F₅)₄] according to Example 2 of U.S. Pat. No. 5,919,983, the entire disclosure of which is herein incorporated by reference.

Preparation of Antioxidant/Stabilizer Additive solution: The additive solution was prepared by dissolving 6.66 g of Irgaphos 168 and 3.33 g of Irganox 1010 in 500 mL of toluene. The concentration of this solution is therefore 20 mg of total additive per 1 mL of solution.

General Procedure for Determining R_v and Comonomer Incorporation

Solution semi-batch reactor copolymerizations of ethylene and octene are carried out in a 1 gallon metal autoclave reactor equipped with a mechanical stirrer, a jacket with circulating heat transfer fluid, which can be heated or cooled in order to control the internal reactor temperature, an internal thermocouple, pressure transducer, with a control computer and several inlet and output valves. Pressure and temperature are continuously monitored during the polymerization reaction. Measured amounts of 1-octene are added to the reactor containing about 1442 g Isopar E as solvent. The reactor is heated up to the reaction temperature with stirring (typically about 1,000 rpm or higher) and then pressurized with ethylene at the desired pressure until the solvent is saturated. The active catalyst is prepared in a drybox by syringing together solutions of the appropriate catalyst, cocatalyst, and any scavenger (if desired) components with additional solvent to give a total volume which can be conveniently added to the reactor (typically 10-20 mL total). If desired, a portion of the scavenger (typically an aluminum alkyl, alumoxane, or other alkyl-aluminum compound) may be added to the reactor separately prior to the addition on the active catalyst solution. The active catalyst solution is then transferred by syringe to a catalyst addition loop and injected into the reactor over approximately 4 minutes using a flow of high pressure solvent. The polymerization is allowed to proceed for the desired length of time while feeding ethylene on demand to maintain a constant pressure. The amount of ethylene consumed during the reaction is monitored using a mass flowmeter. Immediately following the desired polymerization time, the polymer solution is then dumped from the reactor using a bottom-valve through a heated transfer line into a nitrogen-purged glass kettle containing 10-20 mL of isopropanol, which acts as a catalyst kill. An aliquot of the additive solution described above is added to this kettle and the solution stirred thoroughly (the amount of additive used is chosen based on the total ethylene consumed during the polymerization, and is typically targeted at a level of about 1000-2000 ppm). The polymer solution is dumped into a tray, air dried overnight, then thoroughly dried in a vacuum oven for two days. The weights of the polymers are recorded and the efficiency calculated as grams of polymer per gram of transition metal. Because the polymerization of ethylene and alpha olefins is quite exothermic, there is usually an increase in the temperature (an exotherm) of the reaction solution which is observed after the active catalyst is added. The process control computer can be used to keep the reaction temperature relatively constant during the polymerization reaction by cooling the jacket of the reactor, but some deviation from the set point is usually observed, especially for catalysts having a relatively fast initial rate of polymerization. If too much active catalyst is added to the semi-batch reactor, the exotherm can be quite large, and the monomer concentrations, especially the ethylene concentration, can deviate significantly from the equilibrium concentration. Because the polymer molecular weight and the comonomer incorporation depend significantly on the ethylene concentration, it is important to control the exotherm. For the semi-batch reactor polymerizations reported herein, the exotherm was generally kept below 5° C. or less. Various catalysts differ significantly in their rates of polymerization and thus, the amount of exotherm. The exotherm can be controlled by adjusting the amount or rate of addition of the catalyst.

Using the general solution semi-batch reactor polymerization procedure described above, 17 g of 1-octene was added along with 1455 g of ISOPAR-E. This was heated to 160° C., and saturated with ethylene at about 166 psi total reactor pressure. A catalyst solution was prepared by combining solutions of selected Catalyst precursor, Armeenium borate, and MMAO-3A to give 5 μmoles of metal, 6.5 μmoles of Armeenium borate, and 25 μmoles of Al. The catalyst solution was added to the reactor as described in the general procedure. After 10 minutes reaction time, the bottom valve was opened and the reactor contents transferred to the glass kettle containing isopropanol. The additive solution was added and the polymer solution was stirred to mix well. The contents were poured into a glass pan, cooled and allowed to stand in a hood overnight, and dried in a vacuum oven for 2 days.

One method to quantify and identify unsaturation in ethylene-octene Copolymers is ¹H NMR. The sensitivity of ¹H NMR spectroscopy is enhanced by utilizing the technique of peak suppression to eliminate large proton signals from the polyethylene back bone. This allows for a detection limit in the parts per million range in approximately one hour data acquisition time. This is in part achieved by a 100,000-fold reduction of the signal from the —CH₂— protons which in turn allows for the data to be collected using a higher signal gain value. As a result, the unsaturated end groups can be rapidly and accurately quantified for high molecular weight polymers.

The samples were prepared by adding approximately 0.100 g of polymer in 2.5 ml of solvent in a 10 mm NMR tube. The solvent is a 50/50 mixture of 1,1,2,2-tetrachloroethane-d2 and perchloroethylene. The samples were dissolved and homogenized by heating and vortexing the tube and its contents at 130° C. The data was collected using a Varian Unity Plus 400 MHz NMR spectrometer. The acquisition parameters used for the Presat experiment include a pulse width of 30 us, 200 transients per data file, a 1.6 sec acquisition time, a spectral width of 10000 Hz, a file size of 32K data points, temperature setpoint 110° C., D1 delay time 4.40 sec, Satdly 4.0 sec, and a Satpwr of 16.

Comonomer content was measured by ¹³C NMR Analysis. The samples were prepared by adding approximately 3 g of a 50/50 mixture of tetrachloroethane-d2/orthodichlorobenzene to 0.4 g sample in a 10 mm NMR tube. The samples were dissolved and homogenized by heating the tube and its contents to 150° C. The data was collected using a JEOL Eclipse 400 MHz NMR or Varian Unity Plus 400 MHz spectrometer, corresponding to a ¹³C resonance frequency of 100.4 MHz. The data was acquired using NOE, 1000 transients per data file, a 2 sec pulse repetition delay, spectral width of 24,200 Hz and a file size of 32K data points, with the probe head heated to 130° C.

The various amounts of unsaturations and comonomer incorporation by different catalysts prepared by the above-described semi-batch procedure were calculated. Values for the R_v, and the 1-octene incorporation of exemplary catalysts obtained by these methods are recorded in Table IV.

TABLE IV
Catalyst Properties
			Mole %
	Catalyst	Rv	1-octene	Mw
A	(N-(1,1-dimethylethyl)-1,1-di-(4-	0.20	2.62	196,000
	nbutylphenyl)-1-((1,2,3,3a,7a-η)-3-(1,3-
	dihydro-2H-isoindol-2-yl)-1H-inden-1-
	yl)-silanaminato-(2-)-
	N-)dimethyltitanium
B	rac-[1,2-ethanediylbis(1-indenyl)]zir-	0.44	0.64	19,200
	conium (1,4-diphenyl-1,3-butadiene)
C	(C5Me4SiMe2NtBu)Ti(η4-1,3-pentadiene)	0.17	2.01	82,000
D	dimethylsilyl(2-methyl-s-indacenyl)(t-	0.23	2.28	119,400
	butylamido) titanium 1,3-pentadiene
E	[(3-Phenylindenyl)SiMe2NtBut]TiMe2	0.39	2.01	85,700
F	dimethylamidoborane-bis-η5-(2-methyl-	0.34	3.33	44,000
	4-naphthylinden-1-yl)zirconium η4-1,4-
	diphenyl-1,3-butadiene
G	(N-(1,1-dimethylethyl)-1,1-dimethyl-1-	0.44	2.97	105,000
	((1,2,3,3a,9a,-h)-5,6,7,8-tetrahydro-3-
	phenyl-5,5,8,8-tetramethy1-1H-benz-
	(f)inden-1-yl)silanaminato(2-)N)-
	dimethyltitanium
H	bis(n-butylcyclopentadienyl)zirconium	0.16	0.3	10,000
	dimethyl
I	meso-dimethylsilylbis(1-	0.07	1.11	21,600
	indenyl)]hafnium dimethyl

General 1 Gallon Continuous Solution Ethylene Polymerization Procedure

Purified ISOPAR-E solvent, ethylene, and hydrogen are supplied to a 1 Liter reactor equipped with a jacket for temperature control and an internal thermocouple. The solvent feed to the reactor is measured by a mass-flow controller. A variable speed diaphragm pump controls the solvent flow rate and increases the solvent pressure to the reactor. The catalyst feeds are mixed with the solvent stream at the suction of the solvent pump and are pumped to the reactor with the solvent. The cocatalyst feed is added to the monomer stream and continuously fed to the reactor separate from the catalyst stream. The ethylene stream is measured with a mass flow meter and controlled with a Research Control valve. A mass flow controller is used to deliver hydrogen into the ethylene stream at the outlet of the ethylene control valve. The temperature of the solvent/monomer is controlled by use of a heat exchanger before entering the reactor. This stream enters the bottom of the reactor. The catalyst component solutions are metered using pumps and mass flow meters, and are combined with the catalyst flush solvent. This stream enters the bottom of the reactor, but in a different port than the monomer stream. The reactor is run liquid-full at 450 psig with vigorous stirring. The process flow is in from the bottom and out of the top. All exit lines from the reactor are steam traced and insulated. Polymerization is stopped with the addition of a small amount of water, and other additives and stabilizers can be added at this point. The stream flows through a static mixer and a heat exchanger in order to heat the solvent/polymer mixture. The solvent and unreacted monomer are removed at reduced pressure, and the product is recovered by extrusion using a devolatilizing extruder. The extruded strand is cooled under water and chopped into pellets. The operation of the reactor is controlled with a process control computer.

Example 1

Ethylene Polymerization with Catalysts A and B

Using the general continuous solution polymerization procedure described above, ethylene and ISOPAR-E solvent were fed into the reactor at rates of about 4.50 lbs/hour and 26.50 lbs/hour, respectively. The temperature was maintained at about 140° C., and saturated. The polymer of Example 1 was prepared by feeding Catalyst A and Catalyst B, Armeenium borate, and MMAO-3A to the reactor to produce a catalyst concentration of 1.2 ppm, a ratio of catalyst A to catalyst B of 0.34, 22.8 ppm of Armeenium borate, and 4.3 ppm of Al according to the general procedure. The polymer of Example 2 was prepared by feeding Catalyst A and Catalyst B, Armeenium borate, and MMAO-3A to the reactor to produce a catalyst concentration of 0.60 ppm, a ratio of catalyst A to catalyst B of 0.33, 7.6 ppm of Armeenium borate, and 4.3 ppm of Al according to the general procedure. Other process parameters are recorded in Table I.

Examples 2-11

Ethylene Polymerization with Catalysts A and B

The general procedure for continuous solution polymerization described above was repeated for Examples 2-9. Various parameters of the reaction are recorded in Table I.

Examples 11-13

Ethylene/1-Octene Interpolymers Using Catalysts A and B

Ethylene/1-Octene interpolymers were prepared using the general continuous solution procedure described above. Ethylene, 1-octene, and ISOPAR-E solvent were fed into the reactor at rates of about 4.50 lbs/hour, 0.70 lbs/hour, and 30.20 lbs/hour, respectively. The temperature was maintained at about 140° C., and saturated. Examples 3 and 4 were prepared by feeding Catalyst A and Catalyst B, Armeenium borate, and MMAO-3A to the reactor to produce a catalyst concentration of 2.36 ppm, a ratio of catalyst A to catalyst B of 0.44, 53.2 ppm of Armeenium borate, and 8.6 ppm of Al according to the general procedure. Other process parameters are also recorded in Table V.

TABLE V
Polymerization conditions and properties of resulting polymer
		ethylene	solvent.	octene	H2	ethylene
	temper-	flow,	flow,	flow,	flow,	conver-
Example	ature, C.	lb./hr	lb/hr	lb/hr	sccm	sion, %
1	140.3	4.50	22.6	0.00	50.0	90.23
2	139.0	4.50	26.5	0.00	5.0	90.08
3	140.2	4.50	29.2	0.00	0.0	90.20
4	138.5	4.50	31.0	0.00	4.1	94.88
5	140.2	4.50	31.0	0.00	4.7	94.88
6	139.8	4.50	31.0	0.00	6.9	95.15
7	140.9	4.50	31.0	0.00	99.9	97.67
8	140.7	4.50	31.0	0.00	75.0	98.57
9	140.8	4.50	31.0	0.00	64.9	98.53
10	141.0	4.50	26.50	0.00	0.00	90.23
11	140.7	4.50	26.50	0.00	0.00	90.19
12	130.3	4.50	30.20	0.70	0.00	89.97
13	130.9	4.50	30.20	0.70	0.00	90.28
	ppm metal	efficiency,		polymer
	Cat A/	g/g	production	density,
Example	Cat B	metal	rate, lb/hr	g/mL	I2	I10/I2
1	0.65/0.35	14,900,000	4	0.9638	—	—
2	0.65/0.35	20,300,000	4	0.9609	—	—
3	0.65/0.35	20,500,000	4	0.9616	—	—
4	0.65/0.35	9,500,000	4	0.9561	—	—
5	0.65/0.35	9,500,000	4	0.9594	—	—
6	0.65/0.35	9,500,000	4	0.9582	—	—
7	13.52/2.48	500,000	4	0.9579	—	—
8	13.52/2.48	600,000	4	0.9539	—	—
9	13.52/2.48	600,000	4	0.9537	—	—
10	0.31/0.90	30,900,000	4	0.9643	9.17	8.66
11	0.15/0.45	34,000,000	4	0.9643	10.86	8.43
12	0.72/1.64	4,500,000	4	0.9432	1.31	16.34
13	0.72/1.64	4,500,000	4	0.9431	0.97	16.24
			ppm
	Wt %	Wt %	H2 of
	ethyl-	poly-	reactor
Example	ene	mer	feed	Mw	Mn	MWD
1	100	—	—	94,500	12,200	7.75
2	100	—	—	170,400	24200	7.04
3	100	—	—	189,900	18,700	10.16
4	100	—	—	186,400	21,600	8.63
5	100	—	—	149,800	20,500	7.31
6	100	—	—	159,500	13,900	11.47
7	100	—	—	71,700	8750	8.19
8	100	—	—	87,000	15,400	5.65
9	100	—	—	99,600	16,000	6.23
10	100	—	—	56,700	18,900	3.00
11	100	—	—	54,300	36,100	2.89
12	97.4	—	—	112,200	35,100	5.61
13	97.2	—	—	115,100	35,600	5.40

The GPC traces of the polymers of Examples 1-4 were deconvoluted to resolve ion of the high molecular weight component and the low molecular weight FIG. 2 shows the molecular weight distribution and the deconvoluted contributions from the high molecular weight component and the low molecular weight component for the polymer of Example 2. The results of the deconvolutions for Examples 1-13 are collected in Table VI.

TABLE VI
Deconvoluted Polymer Properties
		Mw of High	Mn of High	MWD of	Mw of Low	Mn of Low	MWD of
		MW	MW	High MW	MW	MW	Low MW
Example	Split	Fraction	Fraction	Fraction	Fraction	Fraction	Fraction	MwH/MwL
1	0.28	291708	136383	2.14	32,517	13790	2.36	8.98
2	0.20	606850	297850	2.04	39,335	17816	2.21	15.43
3	0.24	743170	365057	2.04	38817	17897	2.17	19.15
4	0.30	578758	283139	2.04	39415	17713	2.23	14.68
5	0.23	575660	285589	2.02	40421	17785	2.27	14.24
6	0.28	540461	266306	2.03	39871	17603	2.27	13.56
7	0.72	110248	45076	2.45	15566	6301	2.47	7.08
8	0.86	99920	41537	2.41	11688	4734	2.47	8.55
9	0.74	137167	56167	2.44	17418	7049	2.47	7.88
10	0.03	663,868	268,196	2.48	40,908	18,409	2.22	16.22
11	0.03	555,572	273,900	2.03	40,669	18,298	2.22	13.66
12	0.12	691,422	345,719	2.00	38,821	18,292	2.12	17.81
13	0.13	659,512	327,888	2.01	38,981	18,279	2.13	16.91

The polymers from Examples 1-13 were characterized by numerous techniques. Table VII summarizes the physical properties of the polymers of Examples 10-13 obtained in this study. Also included in Table VII for comparison are data for LDPE 6821 and LDPE 170A, which are commercial free-radical LDPE resins available from The Dow Chemical Company.

TABLE VII
Polymer Characterization Data
						LDPE	LDPE
Resin		Example 1	Example 2	Example 3	Example 4	682I	170A
Density	grams/cc	0.9643	0.9643	0.9432	0.9431	0.9211	0.9225
I5		27.99	29.60	5.74	4.27	2.38	2.96
I10	g/10 min	79.47	91.54	21.40	15.75	8.25	9.86
I2	g/10 min	9.17	10.86	1.31	0.97	0.6923	0.5643
I10/I2	—	8.66	8.43	16.34	16.24	11.9	17.5
GPC Data
Mw	—	56,700	54,300	112,200	115,100	84,000	91,700
Mp	—	35600	36100	35100	35600	61,300	56,500
Mn	—	18,900	36,100	35,100	35,600	25,300	17,000
Mw/Mn	—	3.00	2.89	5.61	5.40	3.32	5.39
Melt Strength	cN	7	7	33	36	18	16

The melt strength as a function of the melt index is illustrated in FIG. 3. As FIG. 3 suggests some interpolymers have melt strengths that indicate a higher bubble stability for film fabrication and improved blow molding.

Examples 14-19

5 Gallon Liter Continuous Polymerization of Ethylene

The general procedure described above for the 1 Gallon continuous polymerization of ethylene was applied to a larger 5 gallon liter continuous polymerization reactor. Two catalyst solutions containing 5 ppm of Catalyst A and 10 ppm of catalyst B, respectively, were prepared and added to separate 4 L catalyst storage tanks. These two solutions were fed at a controlled rate and combined in a continuous stream with a continuous stream of ISOPAR-E solvent along with a continuous stream of MMAO-3A to give a molar ratio of catalyst metals:Al of 1:5. The catalyst solution was fed continuously into the reactor at a rate sufficient to maintain the reactor temperature at approximately 140° C. and an ethylene conversion of about 92%. The Armeenium borate cocatalyst solution was mixed with the monomer feed and added separately and continuously fed as an ISOPAR-E solution having a molar ratio of boron:metal of 1.1:1. The production rate for each example was approximately 3.8 Kr/Hour. For each example, the hydrogen feed and catalyst mixture were adjusted to produce an a product having a melt index (I₂) of approximately 1.0. Details for the reactor conditions are recorded in Table VIII.

The polymer solution was continuously removed from the reactor exit and was contacted with a solution containing 100 ppm of water for each part of the polymer solution, and polymer stabilizers. The resulting exit stream was mixed, heated in a heat exchanger, and the mixture was introduced into a separator where the molten polymer was separated from the solvent and unreacted monomers. The resulting molten polymer was extruded and chopped into pellets after being cooled in a water bath. Product samples were collected over 1 hour time periods, after which time the melt index and density was determined for each sample. The melt strength and melt index of the resulting polymers were measured and are also reported in Table VIII.

TABLE VIII
Process Conditions and Polymer Properties for Examples 14-19
									Melt Strength
	Solv	Ethyl	H2	Temp	Catalyst B	Catalyst A	Conv		Force	Velocity
Example	kg/lh	kg/hr	sml/min	° C.	gr/hr	gr/hr	%	I2	(cN)	mm/s
14	32	4.34	0	143	27	135	91.5	0.97	28	41.6
15	32	3.8	19	140	50	45	90	1.27	19	60.8
16	34	3.8	38	140	50	50	92	1.05	13	89.4
17	34	3.8	38	140	50	50	92	0.80	13	77.4
18	34	3.8	54	141	55	67	91.5	0.99	9	134.3
19	34	3.8	54	141	55	69	92	0.82	9	73.2

FIG. 2 plots the melt strength data for ethylene interpolymers of Examples 1-4 and 14-19, as well as for LDPE 6821 as a function of the melt index (I₂).

As demonstrated above, embodiments of the invention provide a new process for making olefin polymers. The novel process may offer one or more of the following advantages. First, the costs associated with this process are similar to those for metallocene catalyzed processes. Good catalyst efficiency is obtained in such a process. The processability of the polymer produced by the process is often better than that of a metallocene catalyzed polymer produced with a single catalyst. Therefore, it is now possible to produce an interpolymer with better processability without sacrificing efficiency and thus incurring higher costs. Because at least two catalysts are used in the polymerization process, it is possible to adjust the density split and the polymer split by selecting the proper catalysts, if desired. By controlling the density split and/or the polymer split, one may design a series of polymers with desired characteristics and properties. With such a process, it is possible to adjust the density split and the polymer split from 0 to 100%. By proper selection of catalysts, it is also possible to increase the level of long chain branching substantially. Moreover, a comb-like long chain branching structure is obtained.

The polymers in accordance with embodiments of the invention may offer one or more of the following advantages. First, the processability and optical properties of certain of the interpolymers are similar to LDPE, while the mechanical properties of certain of the interpolymers are better than LDPE. Moreover, the improved processability is not obtained at the expense of excessive broadening of the molecular weight distribution. The interpolymers also retain many of the desired characteristics and properties of a metallocene catalyzed polymer. In essence, some polymers prepared in accordance with embodiments of the invention combine the desired attributes of LDPE and metallocene catalyzed polymers. Some polymers have higher melt strength than LDPEs at the same molecular weight. Additional advantages are apparent to those skilled in the art.

While the invention has been described with a limited number of embodiments, these specific embodiments are not intended to limit the scope of the invention as otherwise described and claimed herein. Modification and variations from the described embodiments exist. For example, while the high molecular weight catalysts and the low molecular weight catalysts are described with reference to a single site or metallocene catalyst, suitable catalysts are not so limited. It is possible to combine a Ziegler-Natta catalyst with a single site or metallocene catalyst, provided that the catalyst meet the selection criteria for producing a desired polymer. A person of ordinary skill in the art recognizes that catalyst activities may vary, depending on the temperature, pressure, monomer concentration, polymer concentration, hydrogen partial pressure and so on. It should also be recognized that co-catalysts may impact the catalyst's ability to produce interpolymers and the capability to incorporate comonomers. Therefore, one pair of catalysts which does not fulfill the selection criteria under one set of reaction conditions may nevertheless be used in embodiments of the invention under another set of reaction conditions. While all of the embodiments are described with reference to a pair of catalysts, it by no means precludes the use of three, four, five, or more catalysts simultaneously in a single reactor with similar or different capability for molecular weight and/or comonomer incorporation. Although the process is described with reference to the production of interpolymers, homopolymers, such as homopolyethylene, homopolypropylene, homopolybutylene, etc. may also be produced by the process described herein. These homopolymers are expected to have a high level of long chain branching and thus exhibit improved processability while maintaining the desired characteristics possessed by the homopolymers produced by one metallocene catalyst. It should be recognized that the process described herein may be used to make terpolymers, tetrapolymers, or polymers with five or more comonomers. The incorporation of additional comonomers may result in beneficial properties which are not available to copolymers. While the processes are described as comprising one or more steps, it should be understood that these steps may be practiced in any order or sequence unless otherwise indicated. These steps may be combined or separated. Finally, any number disclosed herein should be construed to mean approximate, regardless of whether the word “about” or “approximate” is used in describing the number. The appended claims intend to cover all such variations and modifications as falling within the scope of the invention.

Claims

1. An olefin homopolymer or interpolymer composition, comprising:

a) a backbone chain; and

b) a plurality of long chain branches connected to the backbone;

c) a fraction of the composition having a weight averaged molecular weight, Mw M_w, of 100,000;

d) a fraction of the composition having a weight averaged molecular weight, Mw M_w, of 500,000; and

e) a value of ²g′_LCB-¹g′_LCB g′_2LCB-g′_1LCB of less than about 0.22, where ¹g′_LCB g′_2LCB is the long chain branching index for the fraction of the composition having a M_w of 100,000 and ²g′_LCB g′_1LCB is the long chain branching index for the fraction of the composition having a M_w of 500,000.

2. The composition of claim 1, wherein ²g′_LCB-¹g′_LCB g′_2LCB-g′_1LCB is less than or equal to 0.20.

3. The composition of claim 1, wherein ²g′_LCB-¹g′_LCB g′_2LCB-g′_1LCB is less than or equal to 0.15.

4. The composition of claim 1, wherein ²g′_LCB-¹g′_LCB g′_2LCB-g′_1LCB is less than or equal to 0.12.

5. The composition of claim 1, wherein the composition has a molecular weight distribution greater than 3.0.

6. The composition of claim 1, wherein the composition has a molecular weight distribution from greater than 3.0 to about 12.0.

7. The composition of claim 1 comprising a high molecular weight (HMW) component and a low molecular weight (LMW) component.

8. The composition of claim 7 wherein the composition is multimodal.

9. The composition of claim 7, wherein the composition is bimodal.

10. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein the HMW component has a Mw/Mn of about 1.5 to about 4.0.

11. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein the LMW component has a Mw/Mn of about 1.5 to about 4.0.

12. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein the HMW component has a Mw greater than about 300,000 g/mol.

13. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein the LMW component has a Mw less than about 200,000.

14. The composition of claim 1, wherein the composition is characterized by a DOS of about 5 or higher.

15. The composition of claim 1, wherein the composition is characterized by a DOS of about 5 to about 50,000.

16. The composition of claim 1, wherein the composition is characterized by a DOS of about 20 or higher.

17. The composition of claim 1, wherein the composition is characterized by a DOS of about 20 to about 50,000.

18. The composition of claim 1, wherein the composition is characterized by a DOS of 50 or higher.

19. The composition of claim 1, wherein the composition is characterized by a DOS of 100 or higher.

20. The composition of claim 1, wherein the composition is characterized by a DOS of 1000 or higher.

21. The composition of claim 1, wherein the composition is characterized by a DOS of 10000 or higher.

22. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein the HMW component has a molecular weight distribution of less than about 3.0 and the LMW component has a molecular weight distribution of less than about 3.0.

23. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein the HMW component and the LMW component have a substantially equal comonomer incorporation.

24. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein composition has a ratio of the molecular weight of the HMW component to the molecular weight of the LMW component, that is greater than about 10.

25. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein the HMW component comprises from greater than 0% to about 50% by weight of the total composition and the LMW component comprises from about 50% by weight to less than about 100% by weight of the total composition.

26. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein the HMW component comprises from greater than 1% to about 10% by weight of the total composition and the LMW component comprises from about 90% by weight to about 99% by weight of the total composition.

27. The composition according to any one of claims 1, 7, 8, or 9 claim 7, wherein the HMW component comprises from greater than 2% to about 5% by weight of the total composition and the LMW component comprises from about 95% by weight to about 98% by weight of the total composition.

28. The composition of claim 1 wherein the composition has a melt strength (MS) that satisfies the following relationship:

29. The composition of claim 1 wherein the composition has a melt strength (MS) that satisfies the following relationship:

30. The composition of claim 1 wherein the composition has a melt strength (MS) that satisfies the following relationship:

31. The composition of claim 1 wherein the composition has a melt strength (MS) that satisfies the following relationship: