Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/04—Monomers containing three or four carbon atoms
  • C08F210/06—Propene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/62—Refractory metals or compounds thereof
  • C08F4/64—Titanium, zirconium, hafnium or compounds thereof
  • C08F4/659—Component covered by group C08F4/64 containing a transition metal-carbon bond
  • C08F4/65908—Component covered by group C08F4/64 containing a transition metal-carbon bond in combination with an ionising compound other than alumoxane, e.g. (C6F5)4B-X+
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/62—Refractory metals or compounds thereof
  • C08F4/64—Titanium, zirconium, hafnium or compounds thereof
  • C08F4/659—Component covered by group C08F4/64 containing a transition metal-carbon bond
  • C08F4/65912—Component covered by group C08F4/64 containing a transition metal-carbon bond in combination with an organoaluminium compound
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S526/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S526/941—Synthetic resins or natural rubbers -- part of the class 520 series having the transition metal bonded directly to carbon
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S526/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S526/943—Polymerization with metallocene catalysts

Definitions

• Embodiments of the present invention include copolymers of ethylene and propylene, in the substantial absence of dienes. More specifically, the copolymers are made in a process that employs a single reactor, in steady state.
• Ethylene propylene copolymers made with metallocene catalysts are known. Many such copolymers are intermolecularly heterogeneous in terms of tacticity, composition (weight percent comonomers) or both. Further, such polymers may also, or in the alternative, be compositionally heterogeneous within a polymer chain. Such characteristics may be, but are not always, the result of multiple reactor schemes or sequential addition of polymer.
• U.S. Patent No. 5,504,172 suggests a propylene elastomer that has properties such that: (a) the elastomer contains propylene units in an amount of 50 to 95% by mol and ethylene units in an amount of 5 to 50 % by mol;
• a proportion of inversely inserted propylene units based on the 2,1- insertion of a propylene monomer in all propylene insertions, as measured by 13 C NMR, is not less than 0.5%, and a proportion of inversely inserted propylene units based on the 1,3 -insertion of a propylene monomer, as measured by 13 C NMR, is not more than 0.05%.
• U.S. Patent No. 5,391,629 suggests block and tapered copolymers of ethylene with an ⁇ -olefm.
• the copolymers are made by a process of sequentially contacting ethylene with an ⁇ -olefin monomer in the presence of an activated cyclopentadienyl catalyst system.
• EP 0 374 695 suggests ethylene-propylene copolymers and a process for preparing them.
• the copolymers have a reactivity ratio product, nr 2 , between 0.5 and 1.5 and an isotactic index greater than 0 percent.
• the copolymers are produced in the presence of a homogeneous chiral catalyst and an alumoxane co- catalyst.
• ethylene-propylene copolymers when produced in the presence of a metallocene catalyst and an activator, in a single steady state reactor, show a surprising and unexpected balance of flexural modulus, tensile strength and elasticity. Moreover, these and other properties of the copolymers show surprising differences relative to conventional polymer blends, such as blends of isotactic polypropylene and ethylene-propylene copolymers.
• the copolymer includes from a lower limit of 5% or 6% or 8% or 10% by weight to an upper limit of 20% or 25% by weight ethylene- derived units, and from a lower limit of 75% or 80% by weight to an upper limit of 95% or 94%o or 92% or 90% by weight propylene-derived units, the percentages by weight based on the total weight of propylene- and ethylene-derived units.
• the copolymer is substantially free of diene-derived units.
• features of the copolymers include some or all of the following characteristics, where ranges from any recited upper limit to any recited lower limit are contemplated: (i) a melting point ranging from an upper limit of less than 110 °C, or less than 90 °C, or less than 80 °C, or less than 70 °C, to a lower limit of greater than 25 °C, or greater than 35 °C, or greater than 40 °C, or greater than 45 °C; (ii) a relationship of elasticity to 500% tensile modulus such that Elasticity ⁇ 0.935M + 12, or Elasticity ⁇ 0.935M + 6, or
• a heat of fusion ranging from a lower limit of greater than 1.0 joule per gram (J/g), or greater than 1.5 J/g, or greater than 4.0 J/g, or greater than 6.0 J/g, or greater than 7.0 J/g, to an upper limit of less than 125 J/g, or less than 100 J/g, or less than 75 J/g, or less than 60 J/g, or less than 50 J/g, or less than 40 J/g, or less than 30 J/g;.
• a triad tacticity as determined by carbon- 13 nuclear magnetic resonance ( 13 C NMR) of greater than 75 %, or greater than 80 %, or greater than 85 %, or greater than 90
• a tacticity index m/r ranging from a lower limit of 4 or 6 to an upper limit of 8 or 10 or 12;
• x a reactivity ratio product r ⁇ r 2 of less than 1.5, or less than 1.3, or less than 1.0, or less than 0.8;
• xi a molecular weight distribution Mw/Mn ranging from a lower limit of 1.5 or 1.8 to an upper limit of 40 or 20 or 10 or 5 or 3;
• (xiii) a solid state proton nuclear magnetic resonance (1H NMR) relaxation time of less than 18 milliseconds (ms), or less than 16 ms, or less than
• (xv) a 500 % tensile modulus of greater than 0.5 MPa, or greater than 0.8 MPa, or greater than 1.0 MPa, or greater than 2.0 MPa.
• the copolymer be made in the presence of a bridged metallocene catalyst, in a single steady-state reactor.
• the present invention is directed to a process for producing an ethylene-propylene copolymer having some or all of the above-recited characteristics, by reacting ethylene and propylene in a steady-state reactor under reactive conditions and in the presence of a bridged metallocene catalyst.
• the invention comprises a solution polymerization process for making the above described semicrystalline ethylene propylene copolymers by using particular catalyst and activator combination that lead to similar molecular weights and crystallinity from polymerization at a higher temperature or alternatively higher molecular weight and/or crystallinity when compared to polymerization processes conducted at a lower temperature using previous catalyst and activator combinations.
• This embodiment involves the use of bulky, non-coordinating activators in conjunction with single sited metallocene catalysts capable of making the polymers described above.
• this embodiment can additionally operate using a higher concentration of the monomers present in the polymerization reactor during polymerization.
• Figure 1 is a plot of the natural log of crystalline intensity (by 1H NMR) versus time in milliseconds; T lp referred to in this description is the slope of the line.
• Figure 2 is a plot of flexural modulus, in MPa, versus 500% tensile modulus, in MPa.
• Figure 3 is a plot of elasticity, in percent, versus 500% tensile modulus, in MPa.
• Figure 4 is a plot of melting point (Tm) in °C, as determined by DSC, versus percent ethylene of copolymers of the invention (triangle symbols) and blends of isotactic polypropylene with copolymers of the invention (diamond symbols).
• Figure 5 is a plot of heat of fusion in J/g as a function of ethylene content and polymerization temperature for samples prepared using the process of the invention and comparative samples.
• Figure 6 is a plot of the Mooney (ML127C) as a function of propylene content in hexane solvent in weight percent and polymerization temperature for the copolymers of the current invention and comparative samples.
• thermoplastic polymer compositions composed of a majority of propylene with a minor amount of ethylene.
• These polymer compositions include a linear, single homogeneous macromolecular copolymer structure. These polymers have limited crystallinity due to adjacent isotactic propylene units and have a melting point as described below. They are generally devoid of any substantial intermolecular heterogeneity in tacticity and comonomer composition, and are substantially free of diene. They are also devoid of any substantial heterogeneity in intramolecular composition distribution. In addition, these thermoplastic polymer compositions are unexpectedly soft and elastic.
• the copolymer includes from a lower limit of 5% or 6% or 8% or 10% by weight ethylene- derived units to an upper limit of 20% or 25% by weight ethylene-derived units.
• These embodiments also will include propylene-derived units present in the copolymer in the range of from a lower limit of 75% or 80% by weight to an upper limit of 95% or 94% or 92% or 90% by weight. These percentages by weight are based on the total weight of the propylene and ethylene-derived units; i.e., based on the sum of weight percent propylene-derived units and weight percent ethylene-derived units being 100%.
• these copolymers are mildly crystalline as measured by differential scanning calorimetry (DSC), and are exceptionally soft, while still retaining substantial tensile strength and elasticity.
• Elasticity as defined in detail hereinbelow, is a dimensional recovery from elongation for these copolymers.
• ethylene compositions lower than the above limits for the copolymer such polymers are generally crystalline, similar to crystalline isotactic polypropylene, and while having excellent tensile strength, they do not have the favorable softness and elasticity.
• the copolymer is substantially amorphous.
• the copolymers be substantially free of diene-derived units.
• Dienes are nonconjugated diolefins which may be incorporated in polymers to facilitate chemical crosslinking reactions.
• Substantially free of diene is defined to be less than 1 % diene, or less ' than 0.5 % diene, or less than 0.1 % diene, or less than 0.05 % diene, or equal to 0 %. All of these percentages are by weight in the copolymer.
• the presence or absence of diene can be conventionally determined by infrared techniques well known to those skilled in the art.
• Sources of diene include diene monomer added to the polymerization of ethylene and propylene, or use of diene in catalysts. No matter the source of such dienes, the above outlined limits on their inclusion in the copolymer are contemplated. Conjugated diene-containing metallocene catalysts have been suggested for the formation of copolymers of olefins. However, polymers made from such catalysts will incorporate the diene from the catalyst, consistent with the inco ⁇ oration of other monomers in the polymerization.
• MWD Molecular weight distribution
• GPC size exclusion chromatography
• SEC size exclusion chromatography
• Nj is the number of molecules having a molecular weight Mj.
• Mz The desired MWD function (e.g., Mw/Mn or Mz/Mw) is the ratio of the corresponding M values. Measurement of M and MWD is well known in the art and is discussed in more detail in, for example, Slade, P. E. Ed., Polymer
• a copolymer is included having a weight average molecular weight (Mw) of from 15,000 - 5,000,000, or from 20,000 to 1,000,000 and a molecular weight distribution Mw/Mn (sometimes referred to as a
• polydispersity index (PDI)) ranging from a lower limit of 1.5 or 1.8 to an upper limit of 40 or 20 or 10 or 5 or 3.
• the copolymers of the invention have a weight average molecular weight that can be calculated by application of the following formula: Mw > 6.10*P*e (3370 T)
• Mw the weight average molecular weight
• T the polymerization reaction temperature in degrees Kelvin
• the copolymer has a single melting point.
• the copolymer can be a random copolymer of ethylene and propylene having a melting point (Tm) by Differential Scanning Calorimetry
• FIG. 4 shows the melting point of propylene-ethylene copolymers of the invention as a function of ethylene weight percent, i.e., weight percent of ethylene-derived units (triangle symbols).
• the diamond symbols in Figure 4 show the melting point of blends of isotactic polypropylene and the inventive copolymers also as a function of weight percent ethylene.
• Figure 4 clearly shows that copolymers of the present invention have a lower melting point than propylene-ethylene copolymer/isotactic polypropylene blends having the same weight percent ethylene.
• Embodiments of our invention include copolymers having a heat of fusion, as determined by DSC, ranging from a lower limit of greater than 1.0 J/g, or greater than 1.5 J/g, or greater than 4.0 J/g, or greater than 6.0 J/g, or greater than 7.0 J/g, to an upper limit of less than 125 J/g, or less than 100 J/g, or less than 75 J/g, or less than 60 J/g, or less than 50 J/g, or less than 40 J/g, or less than
• copolymers of embodiments of our invention have generally isotactic crystallizable propylene sequences, and the above heats of fusion are believed to be due to the melting of these crystalline segments.
• the copolymers of the invention have a heat of fusion that can be calculated by application of the following formula:
• H f 311*(E-18.5) 2 /T
• Hf the heat of fusion, measured as described below
• E the ethylene content (meaning units derived from ethylene) of the copolymer, measured as described below
• T the polymerization reaction temperature in degrees Kelvin.
• the tacticity index is determined herein as "m r", is determined by 13 C nuclear magnetic resonance (NMR).
• the tacticity index m/r is calculated as defined in H.N. Cheng, Macromolecules, 17, 1950 (1984). The designation "m” or
• r describes the stereochemistry of pairs of contiguous propylene groups, "m” referring to meso and “r” to racemic.
• An m/r ratio of 1.0 generally describes a syndiotactic polymer, and an m/r ratio of 2.0 an atactic material.
• An isotactic material theoretically may have a ratio approaching infinity, and many by-product atactic polymers have sufficient isotactic content to result in ratios of greater than
• Copolymers of embodiments of our invention can have a tacticity index m/r ranging from a lower limit of 4 or 6 to an upper limit of 8 or 10 or 12.
• Triad tacticity An ancillary procedure for the description of the tacticity of the propylene units of embodiments of the current invention is.the use of triad tacticity.
• the triad tacticity of a polymer is the relative tacticity of a sequence of three adjacent propylene units, a chain consisting of head to tail bonds, expressed as a binary combination of m and r sequences. It is usually expressed for copolymers of the present invention as the ratio of the number of units of the specified tacticity to all of the propylene triads in the copolymer.
• PPP(mm) + PPP(mr) + PPP(rr) where PPP(mm), PPP(mr) and PPP(rr) denote peak areas derived from the methyl groups of the second units in the following three propylene unit chains consisting of head-to-tail bonds:
• the C NMR spectrum of the propylene copolymer is measured as described in U.S. Patent No. 5,504,172.
• the spectrum relating to the methyl carbon region (19-23 parts per million (ppm)) can be divided into a first region (21.2-21.9 ppm), a second region (20.3-21.0 ppm) and a third region (19.5-20.3 ppm). Each peak in the spectrum was assigned with reference to an article in the journal Polymer, Volume 30 (1989), page 1350.
• the methyl group of the second unit in the three propylene unit chain represented by PPP (mm) resonates.
• the methyl group of the second unit in the three propylene unit chain represented by PPP (mr) resonates, and the methyl group (PPE-methyl group) of a propylene unit whose adjacent units are a propylene unit and an ethylene unit resonates (in the vicinity of 20.7 ppm).
• the methyl group of the second unit in the three propylene unit chain represented by PPP (rr) resonates, and the methyl group (EPE-methyl group) of a propylene unit whose adjacent units are ethylene units resonates (in the vicinity of 19.8 ppm).
• the calculation of the triad tacticity is outlined in the techniques shown in U.S. Patent No. 5,504,172. Subtraction of the peak areas for the error in propylene insertions (both 2,1 and 1,3) from peak areas from the total peak areas of the second region and the third region, the peak areas based on the 3 propylene units- chains (PPP(mr) and PPP(rr)) consisting of head-to-tail bonds can be obtained. Thus, the peak areas of PPP(mm), PPP(mr) and PPP(rr) can be evaluated, and hence the triad tacticity of the propylene unit chain consisting of head-to-tail bonds can be determined.
• the propylene copolymers of embodiments of our invention have a triad tacticity of three propylene units, as measured by C NMR, of greater than 75 %, or greater than 80 %, or greater than 82 %, or greater than 85 %, or greater than 90 %.
• the insertion of propylene can occur to a small extent by either 2,1 (tail to tail) or 1,3 insertions (end to end). Examples of 2,1 insertion are shown in structures 1 and 2 below.
• a peak of the carbon A and a peak of the carbon A' appear in the second region.
• a peak of the carbon B and a peak of the carbon B' appear in the third region, as described above.
• peaks which are not based on the 3 propylene unit chain consisting of head-to-tail bonds are peaks based on the PPE-methyl group, the EPE-methyl group, the carbon A, the carbon A', the carbon B, and the carbon B'.
• the peak area based on the PPE-methyl group can be evaluated by the peak area of the PPE-methine group (resonance in the vicinity of 30.8 ppm), and the peak area based on the EPE-methyl group can be evaluated by the peak area of the EPE-methine group (resonance in the vicinity of 33.1 ppm).
• the peak area based on the carbon A can be evaluated by twice as much as the peak area of the methine carbon (resonance in the vicinity of 33.9 ppm) to which the methyl group of the carbon B is directly bonded; and the peak area based on the carbon A' can be evaluated by the peak area of the adjacent methine carbon (resonance in the vicinity of 33.6 ppm) of the methyl group of the carbon B'.
• the peak area based on the carbon B can be evaluated by the peak area of the adjacent methine carbon
• the peak areas based on the three propylene unit chains (PPP(mr) and PPP(rr)) consisting of head-to-tail bonds can be obtained.
• the peak areas of PPP(mm), PPP(mr) and PPP(rr) can be evaluated, and the triad tacticity of the propylene unit chain consisting of head-to-tail bonds can be determined.
• the proportion of the 2,1 -insertions to all of the propylene insertions in a propylene elastomer was calculated by the following formula with reference to article in the journal Polymer, vol. 30 (1989), p.1350.
• This peak is described as the 1.3 insertion peak and we use the procedure described in U.S. Patent No. 5,504,172, which describes this ⁇ peak and understand it to represent a sequence of four methylene units.
• the proportion (%) of the amount of these errors was determined by dividing the area of the ⁇ peak (resonance in the vicinity of 27.4 ppm) by the sum of all the methyl group peaks and Vi of the area of the ⁇ peak, and then multiplying the resulting value by 100. If an ⁇ -olefin of three or more carbon atoms is polymerized using an olefin polymerization catalyst, a number of inversely inserted monomer units are present in the molecules of the resultant olefin polymer.
• 2,1 -insertion or 1,3 -insertion takes place in addition to the usual 1,2-insertion, such that inversely inserted units such as a 2,1 -insertion or a 1,3-insertion are formed in the olefin polymer molecule (see, Macromolecular Chemistry Rapid Communication, Volume 8, page 305 (1987), by K. Soga, T. Shiono, S. Takemura and W. Kaminski).
• the proportion of inversely inserted propylene units of embodiments of our invention is greater than 0.5 %, or greater than 0.6 %.
• the proportion of inversely inserted propylene units of embodiments of our invention is greater than 0.05 %, or greater than 0.06 %, or greater than 0.07 %, or greater than 0.08 %, or greater than 0.085 percent.
• Homogeneous distribution is defined as a statistically insignificant intermolecular difference of both in the composition of the copolymer and in the tacticity of the polymerized propylene.
• a copolymer For a copolymer to have a homogeneous distribution it must meet the requirement of two independent tests: (i) mtermolecular distribution of tacticity; and (ii) mtermolecular distribution of composition, which are described below. These tests are a measure of the statistically insignificant mtermolecular differences of tacticity of the polymerized propylene and the composition of the copolymer, respectively.
• the copolymer of embodiments of our invention has a statistically insignificant intermolecular difference of tacticity of polymerized propylene between different chains (intermolecularly.). This is determined by thermal fractionation by controlled dissolution generally in a single solvent, at a series of slowly elevated temperatures.
• a typical solvent is a saturated hydrocarbon such as hexane or heptane.
• These controlled dissolution procedures are commonly used to separate similar polymers of different crystallinity due to differences in isotactic propylene sequences, as shown in the article in Macromolecules, Vol. 26, p2064 (1993).
• this fractionation procedure will separate the molecules according to tacticity of the incorporated propylene. This procedure is described below.
• At least 75% by weight, or at least 80%o by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight, or at least 97% by weight, or at least 99% by weight of the copolymer is soluble in a single temperature fraction, or in two adjacent temperature fractions, with the balance of the copolymer in immediately preceding or succeeding temperature fractions.
• These percentages are fractions, for instance in hexane, beginning at 23°C and the subsequent fractions are in approximately 8°C increments above 23°C. Meeting such a fractionation requirement means that a polymer has statistically insignificant intermolecular differences of tacticity of the polymerized propylene .
• the copolymer of embodiments of our invention has statistically insignificant intermolecular differences of composition, which is the ratio of propylene to ethylene between different chains (intermolecular).
• This compositional analysis is by infrared spectroscopy of the fractions of the polymer obtained by the controlled thermal dissolution procedure described above.
• each of these fractions has a composition (wt. % ethylene content) with a difference of less than 1.5 wt. % (absolute) or less than 1.0 wt. % (absolute), or less than 0.8 wt. % (absolute) of the average wt. % ethylene content of the whole copolymer.
• Meeting such a fractionation requirement means that a polymer has statistically insignificant intermolecular differences of composition, which is the ratio of propylene to ethylene.
• Uniformity is defined to be a statistically insignificant intramolecular difference of both the composition of the copolymer and in the tacticity of the polymerized propylene.
• For a copolymer to be uniform it must meet the requirement of two independent tests: (i) intramolecular distribution of tacticity; and (ii) intramolecular distribution of composition, which are described below.
• the copolymer of embodiments of our invention has statistically insignificant intramolecular differences of composition, which is the ratio of propylene to ethylene along the segments of the same chain (intramolecular).
• This compositional analysis is inferred from the process used for the synthesis of these copolymers as well as the results of the sequence distribution analysis of the copolymer, for molecular weights in the range of from 15,000-5,000,000 or 20,000-1,000,000.
• the polymerization process is a single stage, steady state, polymerization conducted in a well-mixed continuous feed polymerization reactor.
• the polymerization can be conducted in solution, although other polymerization procedures such as gas phase or slurry polymerization, which fulfil the requirements of single stage polymerization and continuous feed reactors, are contemplated.
• the process can be described as a continuous, non-batch process that, in its steady state operation, is exemplified by removal of amounts of polymer made per unit time, being substantially equal to the amount of polymer withdrawn from the reaction vessel per unit time.
• substantially equal we intend that these amounts, polymer made per unit time, and polymer withdrawn per unit time, are in ratios of one to other, of from 0.9:1; or 0.95:1; or 0.97:1; or 1:1.
• the polymerization is accomplished in substantially single step or stage or in a single reactor, contrasted to multistage or multiple reactors (two or more).
• One method to describe the molecular features of an ethylene-propylene copolymer is monomer sequence distribution.
• the monomer sequence distribution can be determined using spectroscopic analysis. Carbon 13 nuclear magnetic resonance spectroscopy ( C NMR) can be used for this purpose, and can be used to establish diad and triad distribution via the integration of spectral peaks. (If 13 C NMR is not used for this analysis, substantially lower r ⁇ r 2 products are normally obtained.)
• C NMR Carbon 13 nuclear magnetic resonance spectroscopy
• the reactivity ratio product is described more fully in Textbook of Polymer Chemistry, F.W. Billmeyer, Jr., Interscience Publishers, New York, p.221 et seq.
• n is the reactivity of ethylene and r is the reactivity of propylene
• r is the reactivity of propylene
• K ⁇ and Kj 2 are kinetic insertion constants for ethylene; and K 21 and K 22 are kinetic insertion constants for propylene.
• a reactivity ratio product r ⁇ of 0 can define an "alternating" copolymer, and a reactivity ratio product of 1 is said to define a "statistically random” copolymer.
• a copolymer having a reactivity ratio product r t r 2 of between 0.6 and 1.5 is generally said to be random (in strict theoretical terms, generally only a copolymer having a reactivity ratio product r ⁇ _r greater than 1.5 contains relatively long homopolymer sequences and is said to be "blocky”).
• the copolymer of our invention will have a reactivity ratio product r]r of less than 1.5, or less than 1.3, or less than 1.0, or less than 0.8.
• substantially uniform distribution of comonomer within polymer chains of embodiments of our invention generally precludes the possibility of significant amounts of propylene units or sequences within the polymer chain for the molecular weights (weight average) disclosed herein.
• copolymer of embodiments of our invention has statistically insignificant intramolecular differences of tacticity, which is due to isotactic orientation of the propylene units along the segments of the same chain
• the melting point of these polymers depends on the crystallinity, since the more blocky polymers should have a higher melting point as well as depressed solubility in room temperature solvents.
• the R 2 for polypropylene (control) and a copolymer of the current invention are 0.9945 and 0.9967, respectively. Therefore, the T lp relaxation for both polypropylene homopolymer and a copolymer of the current invention can be well fitted by a single- exponential. From the fit, the T lp of polypropylene and a copolymer of the present invention, are calculated as 25 milliseconds (ms) and 8.7 ms, respectively. The large difference in the T lp is reflective of their difference in morphology. The hypothetical polypropylene-like regions would have T lp relaxation similar to that in polypropylene homopolymer.
• T lp 25 ms
• the polymers of the current invention do not contain long continuous isotactic propylene units.
• the T lp , relaxation time can be less than 18 ms, or less than 16 ms, or less than 14 ms, or less than 12 ms, or less than 10 ms.
• a typical isotactic polymerization process consists of a polymerization in the presence of a catalyst including a bis(cyclopentadienyl) metal compound and either (1) a non-coordinating compatible anion activator, or (2) an alumoxane activator.
• this process comprises the steps of contacting ethylene and propylene with a catalyst in a suitable polymerization diluent, the catalyst including, in one embodiment, a chiral metallocene compound, e.g., a bis(cyclopentadienyl) metal compound as described in U.S. Patent No. 5,198,401, and an activator.
• U.S. Patent No. 5,391,629 also describes catalysts useful to produce the copolymers of our invention.
• the catalyst system described below useful for making the copolymers of embodiments of our invention is a metallocene with a non-coordinating anion (NCA) activator, and optionally a scavenging compound.
• NCA non-coordinating anion
• Polymerization is conducted in a solution, slurry or gas phase. The polymerization can be performed in a single reactor process.
• a slurry or solution polymerization process can utilize sub- or superatmospheric pressures and temperatures in the range of from -25 °C to 110 °C.
• a suspension of solid, particulate polymer is formed in a liquid polymerization medium to which ethylene, propylene, hydrogen and catalyst are added.
• the liquid medium serves as a solvent for the polymer.
• the liquid employed as the polymerization medium can be an alkane or a cycloalkane, such as butane, pentane, hexane, or cylclohexane, or an aromatic hydrocarbon, such as toluene, ethylbenzene or xylene.
• liquid monomer can also be used.
• the medium employed should be liquid under the conditions of the polymerization and relatively inert.
• Hexane or toluene can be employed for solution polymerization.
• Gas phase polymerization processes are described in U.S. Patent Nos. 4,543,399, 4,588,790, 5,028,670, for example.
• the catalyst can be supported on any suitable particulate material or porous carrier, such as polymeric supports or inorganic oxides, such as, for example silica, alumina or both.
• Methods of supporting metallocene catalysts are described in U.S. Patent Nos. 4,808,561, 4,897,455, 4,937,301, 4,937,217, 4,912,075, 5,008,228, 5,086,025, 5,147,949, and 5,238,892.
• Propylene and ethylene are the monomers that can be used to make the copolymers of embodiments of our invention, but optionally, ethylene can be replaced or added to in such polymers with a C4 to C20 -olefin, such as, for example, 1-butene, 4-methyl-l-pentene, 1-hexene or 1-octene.
• a C4 to C20 -olefin such as, for example, 1-butene, 4-methyl-l-pentene, 1-hexene or 1-octene.
• metalocene and “metallocene catalyst precursor” are terms known in the art to mean compounds possessing a Group 4, 5, or 6 transition metal M, with a cyclopentadienyl (Cp) ligand or ligands which may be substituted, at least one non-cyclopentadienyl-derived ligand X, and zero or one heteroatom-containing ligand Y, the ligands being coordinated to M and corresponding in number to the valence thereof.
• Cp cyclopentadienyl
• the metallocene catalyst precursors generally require activation with a suitable co-catalyst (sometimes referred to as an activator) in order to yield an active metallocene catalyst, i.e., an organometallic complex with a vacant coordination site that can coordinate, insert, and polymerize olefins.
• a suitable co-catalyst sometimes referred to as an activator
• Preferred metallocenes are cyclopentadienyl complexes which have two Cp ring systems as ligands.
• the Cp ligands preferably form a bent sandwich complex with the metal, and are preferably locked into a rigid configuration through a bridging group.
• cyclopentadienyl complexes have the general formula: (Cp 1 R 1 m )R 3 n (Cp 2 R 2 p )MX q wherein Cp 1 and Cp 2 are preferably the same; R 1 and R 2 are each, independently, a halogen or a hydrocarbyl, halocarbyl, hydrocarbyl-substituted organometalloid or halocarbyl-substituted organometalloid group containing up to 20 carbon atoms; m is preferably 1 to 5; p is preferably 1 to 5; preferably two R and/or R substituents on adjacent carbon atoms of the cyclopentadienyl ring associated therewith can be joined together to form a ring containing from 4 to 20 carbon atoms; R 3 is a bridging group; n is the number of atoms in the direct chain between the two ligands and is preferably 1 to 8, most preferably 1 to 3; M is a transition metal
• Illustrative, but not limiting examples of preferred biscyclopentadienyl metallocenes of the type described above are the racemic isomers of: ⁇ -(CH 3 ) 2 Si(indenyl) 2 M(Cl) 2 , ⁇ -(CH 3 ) 2 Si(indenyl) 2 M(CH 3 )_, ⁇ -(CH 3 ) 2 Si(tetrahydroindenyl) 2 M(Cl) 2 , ⁇ -(CH 3 ) 2 Si(tetrahydroindenyl) 2 M(CH 3 ) 2 , ⁇ -(CH 3 ) 2 Si(indenyl) 2 M(CH 2 CH 3 ) 2 , and ⁇ -(C 6 H 5 ) 2 C(indenyl) 2 M(CH 3 ) 2 , wherein M is Zr, Hf, or Ti.
• Non-coordinating anions ⁇ -(CH 3 ) 2 Si(indenyl) 2 M(Cl) 2 ,
• non-coordinating anion means an anion which either does not coordinate to the transition metal cation or which is only weakly coordinated to the cation, thereby remaining sufficiently labile to be displaced by a neutral Lewis base.
• “Compatible” non-coordinating anions are those which are not degraded to neutrality when the initially formed complex decomposes. Further, the anion will not transfer an anionic substituent or fragment to the cation so as to cause it to form a neutral four coordinate metallocene compound and a neutral by-product from the anion.
• Non- coordinating anions useful in accordance with this invention are those which are compatible, stabilize the metallocene cation in the sense of balancing its ionic charge, yet retain sufficient lability to permit displacement by an ethylenically or acetylenically unsaturated monomer during polymerization.
• the anions useful in this invention may be large or bulky in the sense of sufficient molecular size to largely inhibit or prevent neutralization of the metallocene cation by Lewis bases other than the polymerizable monomers that may be present in the polymerization process.
• the anion will have a molecular size of greater than or equal to 4 angstroms.
• Reactive cations other than Bronsted acids capable of ionizing the metallocene compounds include ferrocenium, triphenylcarbonium, and triethylsilyhum cations.
• Any metal or metalloid capable of forming a coordination complex which is resistant to degradation by water (or other Bronsted or Lewis acids) may be used or contained in the anion of the second activator compound.
• Suitable metals include, but are not limited to, aluminum, gold, platinum and the like.
• Suitable metalloids include, but are not limited to, boron, phosphorus, silicon and the like.
• An additional method of making the ionic catalysts uses ionizing anionic pre-cursors which are initially neutral Lewis acids but form the cation and anion upon ionizing reaction with the metallocene compounds.
• ionizing anionic pre-cursors which are initially neutral Lewis acids but form the cation and anion upon ionizing reaction with the metallocene compounds.
• tris(pentafluorophenyI) boron acts to abstract an alkyl, hydride or silyl ligand to yield a metallocene cation and stabilizing non-coordinating anion; see EP-A-0 427 697 and EP-A-0 520 732.
• Ionic catalysts for addition polymerization can also be prepared by oxidation of the metal centers of transition metal compounds by anionic precursors containing metallic oxidizing groups along with the anion groups; see EP-A-0 495 375.
• Suitable activators capable of ionic cationization of the metallocene compounds of the invention, and consequent stabilization with a resulting non-coordinating anion include: trialkyl-substituted ammonium salts such as: triethyla monium tetraphenylborate; tripropy lammonium tetraphenylborate ; tri(n-butyl)ammonium tetraphenylborate; trimethylammonium tetrakis(p-tolyl)borate; trimethylammonium tetrakis(o-tolyl)borate; tributylammonium tetrakis(pentafluorophenyl)borate; tripropylammonium tetrakis(o,p-dimethylphenyl)borate; tributylammonium tetrakis(m,m-dimethylphenyl)borate; tributylammonium tetrakis
• N,N-dialkyl anilinium salts such as: N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate;
• N,N-dimethylanilinium tetraphenylborate N,N-diethylanilinium tetraphenylborate
• dialkyl ammonium salts such as: di-(isopropyl)ammonium tetrakis(pentafluorophenyl)borate; dicyclohexylammonium tetraphenylborate and the like
• triaryl phosphonium salts such as: triphenylphosphonium tetraphenylborate; tri(methylphenyl)phosphonium tetraphenylborate; tri(dimethylphenyl)phosphonium tetraphenylborate and the like.
• suitable anionic precursors include those comprising a stable carbonium ion, and a compatible non-coordinating anion. These include: tropy Ilium tetrakis(pentafluorophenyl)borate ; triphenylmethylium tetrakis(pentafluorophenyl)borate; benzene (diazonium) tetrakis(pentafluorophenyl)borate; tropy Ilium phenyltris(pentafluorophenyl)borate ; triphenylmethylium phenyl-(trispentafluorophenyl)borate; benzene (diazonium) phenyl-tris(pentafluorophenyl)borate; tropy Ilium tetrakis(2,3 ,5 ,6-tetrafluorophenyl)borate; triphenylmethylium tetrakis(2,3,5,6-tetrafluoroph
• a catalyst system of ⁇ -(CH 3 ) 2 Si(indenyl) 2 Hf(CH 3 ) 2 with a cocatalyst of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, can be used.
• the activating cocatalyst, precursor ionic compounds comprise anionic Group 13 element complexes having four halogenated aromatic ligands typically bulkier than substituted tetraphenyl boron compounds of the exemplified in the identified prior art.
• aromatic ligands consist of polycyclic aromatic hydrocarbons and aromatic ring assemblies in which two or more rings (or fused ring systems) are joined directly to one another or together. These ligands, which may be the same or different, are covalently bonded directly to the metal/metalloid center.
• the aryl groups of said halogenated tetraaryl Group 13 element anionic complex comprise at least one fused polycyclic aromatic hydrocarbon or pendant aromatic ring.
• Indenyl, napthyl, anthracyl, heptalenyl and biphenyl ligands are exemplary.
• the number of fused aromatic rings is unimportant so long as the ring junctions and especially the atom chosen as the point of connection to the Group 13 element center permit an essentially tetrahedral structure.
• suitable ligands include those illustrated below, the open bond being to the Group 13 atom. See also the polycyclic compound examples in the literature for additional ligand selection, e.g., Nomenclature of Organic Compounds, Chs. 4-5 (ACS, 1974).
• ligand connection point is particularly important. Substituents or ring junctions ortho to the ligand connection point present such steric bulk that adoption of an essentially tetrahedral geometry is largely precluded. Examples of undesirable connection points are depicted below.
• Suitable mixed-ligand Group 13 complexes can include fused rings or ring assemblies with ort jo-substituents, or ring junctions, so long as those ligands do not exceed two in number.
• Group 13 anions with one or two hindered fused ring aromatics with three or two unhindered ligands, where hindered aromatics are those having ortho substituents or ring junctions (illustration II) and unhindered are those without (illustration I) will typically be suitable.
• Tris(perfluorophenyl) (perfluoroanthracyl) borate is an illustrative complex.
• the anthracyl ligand is a hindered fused ring having ortho -substituents but its use with three unhweard phenyl ligands allows the complex to adopt a tetrahedral structure.
• the Group 13 complexes useful in a accordance with the invention will typically conform to the following formula :
• M is a Group 13 element
• A is an unhindered ligand as described above
• B is a hindered ligand as described above
• n 1,2.
• halogenation is highly preferred so as to allow for increased charge dispersion that contributes along with steric bulk as independent features decreasing the likelihood of ligand abstraction by the strongly Lewis acidic metallocene cation formed in the catalyst activation. Additionally, halogenation inhibits reaction of the hafnium cation with any remaining carbon-hydrogen bonds of the aromatic rings, and perhalogenation precludes such potential undesirable reactions. Thus it is preferred that at least one third of hydrogen atoms on carbon atoms of the aryl ligands can be replaced by halogen atoms, and more preferred that the aryl ligands be perhalogenated. Fluorine is the most preferred halogen.
• Means of preparing ionic catalyst systems comprising catalytically active cations of the hafnium compounds and suitable noncoordinating anions are conventionally known, see for example U.S. patent 5,198,401, WO 92/00333, and WO 97/22639.
• the methods comprise obtaining from commercial sources or synthesizing the selected transition metal compounds comprising an abstractable ligand, e.g., hydride, alkyl or silyl group, and contacting them with a noncoordinating anion source or precursor compound in a suitable solvent.
• the anion precursor compound abstracts a univalent hydride, alkyl or silyl ligand that completes the valency reqirements of the preferred hafnium metallocene compounds.
• the abstraction leaves the hafnocenes in a cationic state which is counterbalanced by the stable, compatible and bulky, noncoordinating anions according to the invention.
• the noncoordinating anions are preferably introduced into the catalyst preparation step as ionic compounds having an essentially cationic complex which abstracts a non-cyclopentadienyl, labile ligand of the transition metal compounds which upon abstraction of the non-cyclopentadienyl ligand, leave as a by-product the noncoordinating anion portion.
• Hafnium compounds having labile hydride, alkyl, or silyl ligands on the metal center are highly preferred for the ionic catalyst systems of this invention since known in situ alkylation processes may result in competing reactions and interactions that tend to interfere with the overall polymerization efficiency under high temperature conditions in accordance with the preferred process embodiments of the invention.
• Suitable cations for precursor compounds capable of providing the noncoordinating anions of the invention cocatalysts include those known in the art. Such include the nitrogen-containing cations such as those in U.S. patent
• Examples of preferred precursor salts of the noncoordinating anions capable of ionic cationization of the metallocene compounds of the invention, and consequent stabilization with a resulting noncoordinating anion include trialkyl- substituted ammonium salts such as triethylammonium tetrakis(perfluoronapthyl) or tetrakis(perfluoro-4-biphenyl)boron, tripropylammonium tetrakis(perfluoronapthyl) or tetrakis(perfluoro-4-biphenyl)boron, tri(n- butyl)ammonium tetrakis(perfluoronapthyl) or tetrakis(perfluoro-4- biphenyl)boron, trimethylammonium tetrakis(perfluoronapthyl) or tetrakis(perfluoro-4-biphenyl)boron, trimethylammonium tetra
• suitable anionic precursors include those comprising a stable carbenium ion, and a compatible non-coordinating anion. These include tropillium tetrakis(perfluoronapthyl) or tetrakis(perfluoro-4-biphenyl) borate, triphenylmethylium tetrakis(perfluoronapthyl) or tetrakis(perfluoro-4-biphenyl) borate, benzene (diazonium) tetrakis(perfluoronapthyI) or tetrakis(perfluoro-4- biphenyl) borate, tropillium tetrakis(perfluoronapthyl) or tetrakis(perfluoro-4- biphenyl)borate, triphenylmethylium tetrakis(perfluoronapthyl) or tetrakis(perfluoro-4-biphenyl)borate, trip
• the NCA portion comprises an acetylene group and is sometimes referred to as an "acetyl-aryl" moiety.
• a distinguishing feature of invention NCAs is the presence of an acetylenic functional group bound to a Group- 13 atom.
• the Group- 13 atom also connects to at least one fluorinated ring moiety: monofluorinated up through perfluorinated.
• the Group- 13 atom has two other ligands that may also be ring moieties similar to or different from the first ring moiety and may be monofluorinated to perfluorinated.
• the goal of fluorination is to reduce the number of abstractable hydrogen.
• a ligand is referred to as substantially fluorinated when enough hydrogen has been fluorine-replaced so that the amount of remaining abstractable hydrogen is small enough that it does not interfere with commercial polymerization.
• NCA An exemplary invention NCA is shown below.
• Tr stands for triel, which, for this disclosure, encompasses B and Al.
• this NCA is called tris(2',3,3 , ,4,4',5,5',6,6'-nonafluorobiphen-2-yl)(2- perfluorophenylethyn-2-yl)borate.
• the cationic portion of activators according to this embodiment preferably has the form R 3 P11H, wherein R represents an alkyl or aryl moiety; Pn represents a pnictide; N, P, or As; and H is hydrogen. Suitable R are shown below. This list does not limit the scope of the invention; any R that allows the cationic portion to function as described is within the scope of this invention.
• R includes, but is not limited to, methyl, phenyl, ethyl, propyl, butyl, hexyl, octyl, nonyl, 3-ethylnonyl, isopropyl, n-butyl, cyclohexyl, benzyl, trimethylsilyl, triethylsilyl, tri-n- propylsilyl, tri-isopropylsilyl, methylethylhexylsilyl, diethylnonlysilyl, triethylsilylpropyl, 2,2-dimethyloctyl, triethylsilylethyl, tri-n-propylsilylhexyl, tri- isopropylsilyloctyl, and methyldiethylsilyloctyl.
• the copolymers of the current invention have an elongation of greater than 1000%, or greater than 1200%, or greater than 1500%.
• the copolymers of the current invention have a tensile strength greater than 300 psi (2.1 MPa), or greater than 500 psi (3.5 MPa) or greater than 1000 psi (6.9 MPa).
• Tensile and elongation properties are determined at 20 in/ min (51 cm/min) according to the procedure described in ASTM D790. The data is reported in engineering units with no correction to the stress for the lateral contraction in the specimen due to tensile elongation.
• the tensile and elongation properties of embodiments of our invention are evaluated using dumbbell-shaped samples. The samples are compression molded at 180°C to 200°C for 15 minutes at a force of 15 tons (133 kN) into a plaque of dimensions of 6 in x 6 in (15 cm x 15 cm). The cooled plaques are removed and the specimens are removed with a die.
• the elasticity evaluation of the samples is conducted on an Instron 4465, made by Instron Corporation of 100 Royall Street, Canton, MA.
• the digital data is collected in a file collected by the Series IX Material Testing System available from Instron Corporation and analyzed using Excel 5, a spreadsheet program available from Microsoft Corporation of Redmond, WA.
• Embodiments of our invention are elastic after tensile deformation.
• the elasticity represented by the fractional increase in the length of the sample, represented as percent of the length of the sample, is measured according to the general procedure ASTM D790.
• ASTM D790 The elasticity is measured according to the general procedure ASTM D790.
• the copolymer sample is stretched, and the polymer attempts to recover its original dimensions when the stretching force is removed. This recovery is not complete, and the final length of the relaxed sample is slightly longer than that of the original sample.
• Elasticity is represented by the fractional increase in the length of the sample, expressed as a percent of the length of the original un-stretched sample.
• the protocol for measuring the elasticity of the sample consists of prestretching the deformable zone of the dumbbell, made according to the procedure described above for the measurement of elongation and tensile strength, which is the narrow portion of the specimen, to 200% of its original length to prestretch the sample. This is conducted at a deformation rate of 10 inches (25 cm) per minute.
• the sample is relaxed at the same rate to form an analytical specimen which is a prestretched specimen of the original sample.
• This slightly oriented, or prestretched, sample is allowed to relax for 48 hours, at room temperature, prior to the determination of elasticity.
• the length of the deformation zone in the sample is measured to be di. After the 48 hours, it is again deformed at
• Embodiments of the invention have elasticity, as measured by the procedure described above, of less than 30%, or less than 20%, or less than 10%, or less than 8% or less than 5%.
• the copolymer of embodiments of our invention should have a measurable tensile strength at 500% elongation (also known as 500% tensile modulus), of greater than 0.5 MPa, or greater than
• the copolymer should have the above-described elasticity.
• Flexural Modulus Softness of the copolymers of embodiments of the invention may be measured by flexural modulus.
• Flexural modulus is measured in accordance with ASTM D790, using a Type IV dogbone at crosshead speed of 0.05 in/min (1.3 mm/min).
• the values of the flexural modulus over the range of composition of the copolymer vary with the tensile strength of the sample as measured by the 500% tensile modulus.
• Flexural modulus of this family of copolymers is thus represented by two criteria: (a) extensibility to 500% elongation with a measurable modulus (500% tensile modulus); and (b) flexural modulus.
• flexural modulus in MPa is plotted versus 500% tensile modulus in MPa for copolymers of the invention.
• the plotted data correspond to Samples 15-19 in Table 7 of the Examples herein.
• a single exponential fit of the data yields a relationship of:
• Flexural Modulus (MPa) 4.1864e°- 269M where M is the 500% tensile modulus in MPa.
• the flexural modulus in MPa as a function of 500% tensile modulus in MPa is defined by:
• Mn and Mw molecular weight distribution
• Mw molecular weight distribution
• DSC Differential Scanning Calorimetry
• the thermal output is recorded as the area under the melting peak of the sample, which is typically peaked at about 30°C to about 175°C and occurs between the temperatures of about 0°C and about 200°C, and is measured in joules as a measure of the heat of fusion.
• the melting point is recorded as the temperature of the greatest heat absorption within the range of melting of the sample.
• Intermolecular composition distribution of the copolymer is measured as described below. Nominally 30 grams of the copolymer is cut into small cubes with about 1/8" (3 mm) sides. This is introduced into a thick- walled glass bottle with a screw cap closure, along with 50 mg of Irganoxl076, an antioxidant commercially available from Ciba-Geigy Corporation. Then, 425 mL of hexane (a principal mixture of normal and iso isomers) is added to the bottle and the sealed bottle is maintained at 23°C for 24 hours. At the end of this period, the solution is decanted and the residue is treated with additional hexane for an additional 24 hours.
• hexane a principal mixture of normal and iso isomers
• the two hexane solutions are combined and evaporated to yield a residue of the polymer soluble at 23 °C.
• To the residue is added sufficient hexane to bring the volume to 425 mL and the bottle is maintained at 31°C for 24 hours in a covered circulating water bath.
• the soluble polymer is decanted and an additional amount of hexane is added for another 24 hours at 31°C prior to decanting.
• fractions of the copolymers soluble at 40°C, 48°C, 55°C and 62°C are obtained at temperature increases of approximately 8°C between stages.
• Continuous polymerization of the polymer is conducted in a 9 liter Continuous Flow Stirred Tank Reactor using hexane as the solvent.
• the liquid full reactor has a residence time of 9 minutes and the pressure is maintained at 700 kPa.
• a mixed feed of hexane, ethylene and propylene is pre-chilled to approximately -30°C to remove the heat of polymerization, before entering the reactor.
• Solutions of catalyst/activator in toluene and the scavenger in hexane are separately and continuously admitted into the reactor to initiate the polymerization.
• the reactor temperature is maintained between 35 and 50°C, depending on the target molecular weight.
• the feed temperature is varied, depending on the polymerization rate to maintain a constant reactor temperature.
• the polymerization rate is varied from about 0.5 kg/hr to about 4 kg/hr.
• a dilute solution of triisobutyl aluminum is introduced into the reactor as a scavenger of catalyst terminators; a rate of approximately 111 mol of scavenger per mole of catalyst is adequate for this polymerization
• a representative sample of the polymer produced in this polymerization is collected, and then steam-distilled to isolate the polymer.
• the polymerization rate is measured as 3.7 kg/hr.
• the polymer produced in this polymerization has an ethylene content of 14%, ML (1+4) 125°C (Mooney Viscosity) of 13.1 and has isotactic propylene sequences.
• Variations in the composition of the polymer are obtained principally by changing the ratio of ethylene to propylene.
• Molecular weight of the polymer is varied by either changing the reactor temperature or by changing the ratio of total monomer feed rate to the polymerization rate.
• Table 4 describes the composition of the fractions of the copolymer obtained in Table 3. Only fractions which have more than 4% of the total mass of the polymer have been analyzed for composition.
• Table 4 Composition of fractions of the copolymer component obtained in Table 3
• the experimental inaccuracy in the determination of the ethylene content is believed to be approximately 0.4 wt% absolute.
• Continuous Polymerization of the polymer was conducted in a 1 liter internal volume Continuous Flow Stirred Tank Reactor using hexane as the solvent.
• the liquid full reactor had a variable residence time of approximately 9 to 15 minutes (as described in the table below) and the pressure was maintained at 700 kpa.
• a mixed feed of Hexane, ethylene and propylene was pre-chilled to approximately -30°C to remove the heat of polymerization, before entering the reactor.
• the pre-chilling temperature was adjusted to maintain indicated solution polymerization temperature.
• the solution of catalyst/activator in Toluene and the scavenger in hexane were separately and continuously admitted into the reactor to initiate the polymerization.
• the reactor temperature was maintained between 50 and 95°C and the polymerization rate could be varied from 0.1 kg/hr to 0.5 kg/hr as shown in Tables 8 through 13, below. Hexane, ethylene, and propylene were fed to the reactor at the rates shown in Tables 8 through 12.
• the polymerization catalyst, dimethyl silyl bridged bis- indenyl Hafnium dimethyl was activated in vitro with 1 : 1 molar ratio with NCA indicated below in the tables and introduced into the polymerization reactor at the rate of 0.0135 g/hr. Two NCA's were used: N', N'-Dimethyl anilinium-tetrakis (pentafluorophenyl)borate (Al) and N, N'-Dimethyl anilinium-tetrakis
• Crystallinity was measured by DSC and the amount of mm triads of propylene residues in the polymer chain was determined by C NMR. As we have mentioned above the crystallinity and mm triads determination are redundant determinations since the crystallinity of the polymers are dependent only on the isotactic propylene residues.
• the data in the tables below shows the effect of the changes in the polymerization conditions (temperature, NCA and residual monomer concentration) on propylene / ethylene copolymers made at two distinct compositions. The first composition contains approximately 7 wt% ethylene and the second contains approximately 14 wt% ethylene. The data will show that the benefits of the invention are available across the composition range for these propylene-ethylene polymers.
• This example illustrates the difference in the polymerization of Al and A2 with the polymerization being conducted at a range of increasing temperatures between 50°C and 95°C.
• the same polymerization monomer, solvent and catalyst feed are used to make polymers of essentially identical composition.
• the rise in the polymerization temperature lowers the crystallinity and molecular weight of the polymer, however the replacement of Al by A2 raises both the crystallinity as well as the molecular-weight.
• This example illustrates the difference in the polymerization of Al and A2 with the polymerization being conducted at a temperature of 95°C. During each series of polymerization the composition of the polymer is held essentially constant but the residual level of monomer is progressively raised. For both Al and A2 activated polymerization the rise in the residual monomer concentration raises the crystallinity of the propylene residues in the polymer.
• This example illustrates the difference in the polymerization of Al and A2 with the polymerization being conducted at a temperature of 95°C.
• the composition of the polymer is held essentially constant but the residual level of monomer is progressively raised.
• the rise in the residual monomer concentration raises the crystallinity of the propylene residues in the polymer.
• the examples differ from the data in examples immediately earlier in that a propylene-ethylene copolymer having a higher ethylene content was made. These data in conjunction indicate that the effect of the replacement of Al by A2 is not limited by the ethylene content of the polymer.
• This example illustrates the difference in the polymerization of Al and A2 with the polymerization being' conducted at a range of increasing temperatures between 50°C and 95°C.
• the same polymerization monomer, solvent and catalyst feed are used to make polymers of essentially identical composition.
• the rise in the polymerization temperature lowers the crystallinity and molecular weight of the polymer, however the replacement of Al by A2 raises both the crystallinity as well as the molecular weight.
• the examples differ from the data in examples 1 -8 earlier in that a propylene-ethylene copolymer having a higher ethylene content was made.
• Samples 77-C through 80-C (comparative): Comparative examples 77-C to 80-C show the comparison of the Mooney viscosity (Mooney viscosity measured as ML (1+4) at 127°C in Mooney units according to ASTM D-1646) of the polymer made with Al for comparison to the data in examples 55 through 68. Since the Mooney viscosity of the copolymers is strongly dependent on the steady sate monomer concentrations the data is plotted as a function of the monomer concentration and the polymerization temperature.
• Mooney viscosity Mooney viscosity measured as ML (1+4) at 127°C in Mooney units according to ASTM D-1646

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