Method for adjusting polymer properties
阅读说明：本技术 用于调节聚合物特性的方法 (Method for adjusting polymer properties ) 是由 J·F·斯祖尔 E·J·玛克尔 R·E·比凯诺 B·J·赛华佗斯凯 于 2019-03-20 设计创作，主要内容包括：本公开的实施例涉及利用由式I表示的茂金属络合物来调节熔融指数和/或密度的方法：<Image he="467" wi="606" file="DDA0002668695740000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>其中每个n-Pr为正丙基,并且每个X独立地为CH<Sub>3</Sub>、Cl、Br或F。(Embodiments of the present disclosure relate to methods of using metallocene complexes represented by formula I to adjust melt index and/or density: wherein each n-Pr is n-propyl, and each X is independently CH 3 Cl, Br or F.)
1. A method for adjusting melt index, the method comprising:
activating a metallocene complex represented by formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F to provide an activated metallocene complex;
contacting a monomer and a comonomer with the activated metallocene complex to produce a first polymer having a predetermined density and a first melt index, wherein the monomer is present in a monomer concentration and the comonomer is present in a comonomer concentration and hydrogen is present in a hydrogen concentration; and
reducing the hydrogen concentration to produce a second polymer having the predetermined density and a second melt index less than the first melt index, wherein comonomer consumption is reduced from 10% to 35% by mass.
2. A method for adjusting density, the method comprising:
activating a metallocene complex represented by formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F to provide an activated metallocene complex;
contacting a monomer and a comonomer with the activated metallocene complex in the presence of hydrogen to produce a first polymer having a first density and a first melt index, wherein the hydrogen is present at a first hydrogen concentration, the monomer is present at a monomer concentration, and the comonomer is present at a comonomer concentration; and
reducing the first hydrogen concentration to a second hydrogen concentration while maintaining the monomer consumption to produce a second polymer having a second density less than the first density and a second melt index less than the first melt index.
3. The method of any of the preceding claims, wherein the hydrogen concentration is reduced from 10 wt% to 40 wt%.
4. The method of any one of the preceding claims, wherein the monomer is ethylene and the comonomer is 1-hexene.
Technical Field
One or more embodiments of the present disclosure relate to a method for adjusting polymer properties; more specifically, one or more embodiments relate to methods of utilizing metallocene complexes represented by formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F.
Background
The polymers are useful in a variety of products, including films and the like. Polymers may be formed by reacting one or more types of monomers in a polymerization reaction. The industry has been working to develop new and improved materials and/or methods that can be used to form polymers.
Disclosure of Invention
The present disclosure provides a method for adjusting melt index, the method comprising: activating a metallocene complex represented by formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F; to provide an activated metallocene complex; contacting a monomer and a comonomer with the activated metallocene complex to produce a first polymer having a predetermined density and a first melt index, wherein the monomer is present in a monomer concentration and the comonomer is present in a comonomer concentrationHydrogen is present in a hydrogen concentration; and reducing the hydrogen concentration to produce a second polymer having the predetermined density and a second melt index less than the first melt index, wherein comonomer consumption is reduced from 10% to 35% by mass.
The present disclosure provides a method for adjusting density, comprising:
activating a metallocene complex represented by formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F to provide an activated metallocene complex; contacting a monomer and a comonomer with an activated metallocene complex in the presence of hydrogen to produce a first polymer having a first density and a first melt index, wherein the hydrogen is present at a first hydrogen concentration, the monomer is present at a monomer concentration, and the comonomer is present at a comonomer concentration; and reducing the first hydrogen concentration to a second hydrogen concentration while maintaining the monomer consumption to produce a second polymer having a second density less than the first density and a second melt index less than the first melt index.
One or more embodiments include reducing hydrogen gas from a first hydrogen concentration to a second hydrogen concentration, wherein the first hydrogen concentration is greater than the second hydrogen concentration.
One or more embodiments provide that the monomer is ethylene and the comonomer is 1-hexene.
The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following description more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each case, the recited list serves only as a representative group and should not be construed as an exclusive list.
Drawings
FIG. 1 shows C6/C2Flow ratio (lb/lb) to I2Graph of melt index.
FIG. 2 shows the density (g/cm)3) And I2Graph of melt index.
Detailed Description
The polymer may have a variety of characteristics, such as melt index, density, and melt index ratio, among others. Specific values of some polymer properties can be obtained by adjusting polymerization parameters such as monomer concentration, reaction temperature, comonomer flow ratio, hydrogen concentration and/or reaction temperature. However, when different catalysts are used, the specific values of the polymer properties obtained by adjusting the polymerization parameters may vary.
The activated metallocenes are useful as catalysts for the production of a variety of polymers. Surprisingly, when activated, the metallocene complexes of formula I
Wherein each n-Pr is n-propyl and each X is independently CH3Cl, Br or F, compared to the metallocene complex of formula II:
wherein each cyclopentadienyl ring is substituted with 1-methyl, 3-butyl, and each X is independently CH3Cl, Br or F, with increased hydrogen response and increased comonomer response. This increased hydrogen response and increased comonomer response may have a significant impact on melt index and/or density.
The present disclosure provides methods for adjusting melt index. The method of adjusting the melt index may include activating a metallocene complex represented by formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F to provide an activated metallocene complex; contacting a monomer and a comonomer with an activated metallocene complex to produce a first polymer having a predetermined density and a first melt index, wherein the monomer is present as a monomerThe comonomer is present in a concentration and the comonomer is present in a comonomer concentration; and reducing the hydrogen concentration and comonomer consumption to produce a second polymer having a predetermined density and a second melt index less than the first melt index. Utilizing a metallocene complex of formula I (e.g., rather than utilizing a metallocene complex of formula II) can advantageously provide polymers that can produce polymers with constant density and lower melt index at reduced comonomer consumption. For many product applications, it may be desirable to use less comonomer. For economic reasons it may also be desirable to reduce the comonomer consumption, since for example 1-hexene is more expensive than ethylene.
The present disclosure provides methods for adjusting density. The method of adjusting density may include activating a metallocene complex represented by formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F to provide an activated metallocene complex; contacting a monomer and a comonomer with an activated metallocene complex in the presence of hydrogen to produce a first polymer having a first density and a first melt index, wherein the hydrogen is present at a first hydrogen concentration, the monomer is present at a monomer concentration, and the comonomer is present at a comonomer concentration; and reducing the hydrogen to a second hydrogen concentration while maintaining the monomer consumption to produce a second polymer having a second density less than the first density and a second melt index less than the first melt index. Utilizing a metallocene complex of formula I (e.g., rather than utilizing a metallocene complex of formula II) can advantageously provide a polymer that can be produced with a lower density and/or melt index by reducing the hydrogen concentration. Because other metallocene complexes (e.g., the metallocene complex of formula II) can generate hydrogen during polymerization, polymers having lower densities and/or melt indices produced by reducing the concentration of hydrogen (i.e., the hydrogen fed to the reactor) may not be available.
As mentioned, the methods disclosed herein utilize metallocene complexes represented by formula I:
wherein each n-Pr is n-propyl and each X is independently CH3Cl, Br or F. Metallocene complexes can be prepared by known methods, such as by repeated deprotonation/metallation of the aromatic ligands and introduction of the bridge and central atoms with their halogen derivatives. Known processes for preparing metallocenes are described in Journal of organometallic chemistry, volume 288, (1985), pages 63-67 and EP-A-320762. Both of these documents are incorporated herein by reference in their entirety. In addition, the metallocene complexes of the formula I and/or the corresponding activated metallocene complexes can be used, for example, under the name XCATTMVP-100 is commercially available from Univariation Technologies, LLC.
One or more embodiments of the present disclosure provide for utilizing supported metallocene complexes. The supported metallocene complex may include a metallocene complex of formula I and a support material. The supported metallocene complex may include other components known in the art.
The supported metallocene complexes can be formed by known methods. For example, the supported metallocene complex may be formed by a slurry process. The slurry may comprise the components of the supported metallocene complex, i.e. the metallocene complex of formula I and the support material, and optionally other known components. For example, the slurry can include an activator, such as an alumoxane and/or a modified alumoxane. The slurry may include an activator and/or a supported activator. In one embodiment, the slurry comprises a support material, an activator, and a metallocene complex of formula I. The molar ratio of the metal in the activator to the metal in the metallocene complex of formula I can be 1000:1 to 0.5:1, 300:1 to 1:1, or 150:1 to 1: 1. Combining a metallocene complex (i.e., the metallocene complex of formula I) with an activator can provide a catalyst, such as an activated metallocene complex.
The support material may be any inert particulate support material known in the art including, but not limited to, silica, fumed silica, alumina, clay or talc, as well as other support materials. In one embodiment, the slurry contains silica and an activator, such as methylalumoxane ("MAO"), modified methylalumoxane ("MMAO"), as discussed further below.
As used herein, the terms "support material", "support" and "carrier" may be used interchangeably and refer to any support material, including porous support materials such as talc, inorganic oxides and inorganic chlorides. The metallocene complex of formula I may be on the same support as the activator, or the activator may be used in unsupported form, or may be deposited on a different support than the metallocene complex of formula I. This may be accomplished by any technique commonly used in the art.
The support material may include one or more inorganic oxides, such as group 2, group 3, group 4, group 5, group 13, or group 14 elements. Inorganic oxides may include, but are not limited to, silica, alumina, titania, zirconia, boria, zinc oxide, magnesium oxide, or combinations thereof. Illustrative combinations of inorganic oxides can include, but are not limited to, alumina-silica, silica-titania, alumina-zirconia, alumina-titania, and the like. The support material may be or include alumina, silica, or a combination thereof. In one embodiment, the support material is silica.
Suitable commercially available silica supports may include, but are not limited to, ES757, ES70, and ES70W, available from PQ corporation (PQ corporation). Suitable commercially available silica-alumina supports can include, but are not limited to, those available from
As used herein, the term "activator" refers to any supported or unsupported compound or combination of compounds that can activate a complex or catalyst component, for example, by generating a cationic species of the catalyst component. For example, this may include abstraction of at least one leaving group (an "X" group as described herein) from the metal center of the complex/catalyst component (e.g., a metallocene complex of formula I). The activator may also be referred to as a "cocatalyst".
The activator may comprise a Lewis acid (Lewis acid) or a non-coordinating ionic activator or an ionizing activator, or any other compound including Lewis bases (Lewis bases), aluminum alkyls, and/or conventional cocatalysts. In addition to the above-mentioned methylaluminoxane ("MAO") and modified methylaluminoxane ("MMAO") illustrative activators may include, but are not limited to, alumoxanes or modified alumoxanes and/or ionizing neutral or ionic compounds, such as dimethylanilinium tetrakis (pentafluorophenyl) borate, triphenylcarbonium tetrakis (pentafluorophenyl) borate, dimethylanilinium tetrakis (3,5- (CF) phosphonium, and mixtures thereof3)2Phenyl) borate, triphenylcarbenium tetrakis (3,5- (CF)3)2Phenyl) borate, dimethylanilinium tetrakis (perfluoronaphthyl) borate, triphenylcarbonium tetrakis (perfluoronaphthyl) borate, dimethylanilinium tetrakis (pentafluorophenyl) aluminate, triphenylcarbonium tetrakis (pentafluorophenyl) aluminate, dimethylanilinium tetrakis (perfluoronaphthyl) aluminate, triphenylcarbonium tetrakis (perfluoronaphthyl) aluminate, tris (perfluorophenyl) boron, tris (perfluoronaphthyl) boron, tris (perfluorophenyl) aluminum, tris (perfluoronaphthyl) aluminum, or any combination thereof.
The activator may or may not be bound directly to the surface of the support, or the activator may be modified to allow it to be bound to the surface of the support, for example by tethering the agent. Such suppositories may be derived from groups reactive with surface hydroxyl species. Non-limiting examples of reactive functional groups that can be used to create tethers include aluminum halides, aluminum hydrides, aluminum alkyls, aluminum aryls, aluminum alkoxides, silicon electrophiles, alkoxysilanes, aminosilanes, boranes.
Aluminoxanes can be referred to as oligomeric aluminum compounds having the-A1 (R) -O-subunit, where R is an alkyl group. Examples of aluminoxanes include, but are not limited to, methylaluminoxane ("MAO"), modified methylaluminoxane ("MMAO"), ethylaluminoxane, isobutylaluminoxane, or combinations thereof. Aluminoxanes can be produced by hydrolysis of the corresponding trialkylaluminum compound. MMAO can be produced by hydrolyzing trimethylaluminum and higher trialkylaluminum (e.g., triisobutylaluminum). There are a variety of known methods for preparing aluminoxanes and modified aluminoxanes. Aluminoxanes may include Modified Methylaluminoxane ("MMAO") type 3A (commercially available from akzo chemicals, Inc.) under the trade designation Modified Methylaluminoxane type 3A, as discussed in U.S. patent No. 5,041,584). The source of MAO may be a solution having, for example, about 1 wt.% to about 50 wt.% MAO. Commercially available MAO solutions may include 10 wt.% and 30 wt.% MAO solutions available from Albemarle Corporation of Bagulu Ri, Baton Rouge, La.
One or more organoaluminum compounds, such as one or more alkylaluminum compounds, can be used in combination with the aluminoxane. Examples of alkyl aluminum compounds include, but are not limited to, diethyl aluminum ethoxide, diethyl aluminum chloride, diisobutyl aluminum hydride, and combinations thereof. Examples of other alkylaluminum compounds (e.g., trialkylaluminum compounds) include, but are not limited to, trimethylaluminum, triethylaluminum ("TEAL"), triisobutylaluminum ("TiBAl"), tri-n-hexylaluminum, tri-n-octylaluminum, tripropylaluminum, tributylaluminum, and combinations thereof.
As used herein, a "polymer" has two or more polymer units derived from monomers and/or comonomers. A "copolymer" is a polymer having two or more polymer units that are different from each other. Polymers and copolymers may be used interchangeably herein. As used herein, "polymerization" and/or "polymerization process" is a process for forming a polymer.
As used herein, when a polymer or copolymer is referred to as comprising, e.g., being formed from, an olefin, the olefin present in such polymer or copolymer is an olefin in polymerized form. For example, when the ethylene content of the polymer is said to be from 75 wt% to 85 wt%, it is understood that the polymer units are derived from ethylene in the polymerization reaction and the derived units are present in an amount of from 75 wt% to 85 wt%, based on the total weight of the polymer.
One or more embodiments of the present disclosure include polymers (i.e., polyethylenes) prepared from monomers (i.e., ethylene) and/or linear or branched high carbon number alpha-olefin comonomers containing from 3 to 20 carbon atoms. Examples of comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 3,5, 5-trimethyl-1-hexene, and combinations thereof. Examples of polymers include, but are not limited to, ethylene-based polymers having at least 50 wt% ethylene, including ethylene-1-butene, ethylene-1-hexene, and ethylene-1-octene, among others.
The polymer may comprise from 50 to 95 wt% ethylene, based on the total weight of the polymer. All individual values and subranges from 50 to 95 wt% are included; for example, the polymer can include a lower limit of 50, 60, or 70 wt% ethylene to an upper limit of 95, 90, or 85 wt% ethylene, based on the total weight of the polymer. The polymer may include from 5 to 50 wt% comonomer, based on the total weight of the polymer. Including all individual values and subranges from 5 to 50 weight percent; for example, the polymer may include a lower limit of 5, 10, or 15 wt% comonomer to an upper limit of 50, 40, or 30 wt% comonomer, based on the total weight of the polymer.
One or more embodiments of the present disclosure provide that the density of the polymer may be at 0.890g/cm3To 0.970g/cm3Within the range. Comprises 0.890 to 0.970g/cm3All individual values and subranges of (a); for example, the density of the polymer may be from a lower limit of 0.890, 0.900, 0.910 or 0920g/cm3To an upper limit of 0.970, 0.960, 0.950 or 0.940g/cm3. The density can be determined according to ASTM D-792.
One or more embodiments of the present disclosure provide for a Melt Index (MI) or (I) of a polymer as measured according to ASTM-D-1238-E2) And may range from 0.01 dg/min to 1000 dg/min. For example, the MI of the polymer can be from 0.01 dg/min to 100 dg/min, from 0.1 dg/min to 50 dg/min, or from 0.1 dg/min to 10 dg/min.
One or more embodiments of the present disclosure provide that the Mn (number average molecular weight) of the polymer may be 5,000 to 75,000. Including all individual values and subranges from 5,000 to 75,000; for example, the Mn of the polymer can be from a lower limit of 5,000; 6,000; 7,000; 7,500; 8,000; or 8,500 to an upper limit of 75,000; 65,000; 55,000; 45,000; 35,000; 25,000; 24,000; 23,000; or 22,000. Mn can be determined by Gel Permeation Chromatography (GPC), as known in the art.
One or more embodiments of the present disclosure provide that the Mw (weight average molecular weight) of the polymer may be from 60,000 to 110,000. Including all individual values and subranges from 60,000 to 110,000; for example, the Mw of the polymer may be from a lower limit of 60,000; 62, 500; 63,000; or 63,500 to an upper limit of 110,000; 109,000; 108,000; or 107,000. Mw may be determined by GPC, as is known in the art.
One or more embodiments of the present disclosure provide that the Mz (z average molecular weight) of the polymer may be from 150,000 to 400,000. Including all individual values and subranges from 150,000 to 400,000; for example, the Mz of the polymer may be from a lower limit of 150,000; 155,000; 160,000; or 170,000 to an upper limit of 400,000; 375,000; 350,000; or 325,000. Mz can be determined by GPC, as known in the art.
One or more embodiments of the present disclosure provide that the polymer may have a molecular weight distribution, as determined by Mw/Mn (weight average molecular weight/number average molecular weight), of from 3.00 to 8.00. Including all individual values and subranges from 3.00 to 8.00; for example, the Mw/Mn of the polymer can be from a lower limit of 3.00; 3.50; 4.00; or 4.50 to an upper limit of 8.00; 7.50 of; 7.00; or 6.50. As is known in the art, Mw/Mn can be determined by GPC analysis.
The polymers may be formed by suspension, slurry and/or gas phase polymerization processes using known equipment and reaction conditions (i.e., known polymerization conditions). The formation of the polymer is not limited to any particular type of polymerization system. For example, the polymerization temperature may range from about 0 ℃ to about 300 ℃ at atmospheric, subatmospheric, or superatmospheric pressure. In particular, slurry or solution polymerization systems may employ subatmospheric or alternatively superatmospheric pressures, and temperatures in the range of from about 40 ℃ to about 300 ℃.
Many embodiments of the present disclosure provide that the polymer can be formed by a gas phase polymerization system at a pressure above atmospheric pressure in the range of 0.07 to 68.9 bar (1 to 1000psig), 3.45 to 27.6 bar (50 to 400psig), or 6.89 to 24.1 bar (100 to 350psig) at a temperature in the range of 30 ℃ to 130 ℃,50 ℃ to 110 ℃, 55 ℃ to 120 ℃, or 70 ℃ to 120 ℃. For many embodiments, the operating temperature may be less than 112 ℃. Stirred and/or fluidized bed gas phase polymerization systems may be used.
In general, conventional gas phase fluidized bed polymerization processes can be carried out by continuously passing a monomer and comonomer containing stream through a fluidized bed reactor under reaction conditions and in the presence of a catalyst composition (e.g., a composition comprising a metallocene complex of formula I and an activator and/or a corresponding activated metallocene complex of formula I) at a velocity sufficient to maintain the bed of solid particles in suspension. The stream comprising unreacted monomer may be continuously recovered from the reactor, compressed, cooled, optionally partially or fully condensed, and recycled back to the reactor. The product, i.e., polymer, can be withdrawn from the reactor and make-up monomer can be added to the recycle stream. Gases inert to the catalyst composition and reactants may also be present in the gas stream. The polymerization system may comprise, for example, a single reactor or two or more reactors in series.
The feed stream for the polymerization process may include monomer, comonomer, nitrogen, hydrogen, and may optionally include one or more non-reactive alkanes that may be condensed in the polymerization process and used to remove the heat of reaction. Illustrative non-reactive alkanes include, but are not limited to, propane, butane, isobutane, pentane, isopentane, hexane, isomers thereof, and derivatives thereof. The feed may enter the reactor at a single location or at multiple different locations.
For the polymerization process, the catalyst (e.g., the metallocene complex of formula I including the activator and/or the corresponding activated metallocene complex of formula I) can be continuously fed into the reactor. A gas inert to the catalyst (e.g., nitrogen or argon) may be used to carry the catalyst into the reactor bed. In another embodiment, the catalyst may be provided as a slurry in mineral oil or a liquid hydrocarbon or mixture (e.g., propane, butane, isopentane, hexane, heptane, or octane). The catalyst slurry may be mixed with a carrier liquid (e.g., nitrogen or argon) and/or a liquid (e.g., isopentane or other C)3To C8Alkane) are delivered together into the reactor.
For the polymerization process, hydrogen can be used in the reactor at a gas molar ratio of hydrogen to ethylene in the range of about 0.0 to 1.0, in the range of 0.00001 to 0.7, in the range of 0.00003 to 0.5, or in the range of 0.00005 to 0.3.
As mentioned, the present disclosure provides a method for adjusting melt index. The method comprises activating a metallocene complex of formula I as described herein
Wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F to provide an activated metallocene complex. The activated metallocene catalyst can be used in a polymerization process that utilizes a monomer (at a monomer concentration) and a comonomer (at a first comonomer concentration) to produce a polymer having a predetermined density and a first melt index.
The method includes adjusting the first comonomer consumption. For example, the first comonomer consumption can be reduced to provide a second comonomer consumption. Adjusting the first comonomer consumption to the second comonomer consumption provides that the second polymer can be produced using the metallocene catalyst and the second comonomer consumption. The comonomer consumption can be reduced from 10% to 35% by mass. Including all individual values and subranges from 10 to 35% by mass; for example, the comonomer consumption may be reduced from a lower limit of 10%, 11%, 12% or 15% by mass to an upper limit of 35%, 33%, 32% or 30% by mass.
One or more embodiments of the present disclosure provide for the second polymer to have a predetermined density, e.g., the polymerization that produces the first polymer and the polymerization that produces the second polymer are of constant density. As used herein, "constant density" indicates that the first polymer and the second polymer each have a difference of 0.002g/cm from each other3Respective densities within. For example, if the density of the first polymer is 0.918g/cm3The density of the second polymer may then be 0.9180 + -0.002 g/cm3。
One or more embodiments of the present disclosure provide that the second polymer has a second melt index. For example, when the first hydrogen concentration is reduced to provide the second hydrogen concentration; the resulting second melt index is less than the first melt index, e.g., the melt index is adjusted to a lower melt index. Advantageously, the use of the metallocene complexes of formula I discussed herein can provide polymers with constant density and lower melt index with reduced comonomer consumption. For many product applications, it may be desirable to use less comonomer. For economic reasons it may also be desirable to reduce the comonomer consumption, since for example 1-hexene is more expensive than ethylene.
As mentioned, the present disclosure provides a method for adjusting density. The method comprises activating a metallocene complex of formula I as discussed herein:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F to provide an activated metallocene complex. The activated metallocene catalyst can be used in a polymerization process utilizing a monomer (at a monomer concentration) and a comonomer (at a comonomer concentration) in the presence of hydrogen (at a first hydrogen concentration) to produce a first polymer having a first density and a first melt index.
The method includes reducing the hydrogen concentration to a second hydrogen concentration less than the first hydrogen concentration while maintaining the monomer concentration and the comonomer concentration to produce a second polymer. One or more embodiments of the present disclosure provide for maintaining comonomer consumption. As used herein, "comonomer consumption" is determined from the mass flow ratio of comonomer to monomer. The comonomer flow ratio is the comonomer feed rate divided by the monomer feed rate by mass. The feed streams of monomer and comonomer include all sources of monomer and comonomer feed to the reactor recycle loop, including fresh feed, recovered liquid, recovered gas, or as a component in other feed streams. The first polymer and the second polymer each have respective comonomer/monomer flow ratios within 10% of each other. For example, if the first polymer is produced by polymerization with a comonomer/monomer flow ratio of 0.067, the second polymer is produced by polymerization with a comonomer/monomer flow ratio of 0.067 ± 0.0067.
One or more embodiments of the present disclosure provide that the second polymer has a second density. For example, when the hydrogen concentration is reduced to provide a second hydrogen concentration, where comonomer consumption remains constant; the resulting second density is less than the first density, e.g., the density is adjusted to a lower density.
Further, one or more embodiments of the present disclosure provide that the second polymer has a second melt index. For example, when the hydrogen concentration is reduced to provide a second hydrogen concentration; the resulting second melt index is less than the first melt index, e.g., the melt index is adjusted to a lower melt index.
Utilizing a metallocene complex of formula I (e.g., rather than utilizing a metallocene complex of formula II) can advantageously provide a polymer that can be produced with lower density and/or lower melt index by reducing the hydrogen concentration. Because other metallocene complexes (e.g., the metallocene complex of formula II) can generate hydrogen during polymerization, polymers having lower densities and/or lower melt indices produced by reducing the concentration of hydrogen (i.e., the hydrogen fed to the reactor) may not be available.
Examples of the invention
In examples, various terms and names of materials are used, including, for example, the following:
XCATTMVP-100 (an activated metallocene complex of formula I, available from Univariation Technologies, LLC); XCATTMHP-100 (activated metallocene complex of formula II available from Univariation Technologies, LLC).
Melt index (I) according to ASTM D-1238-E2) (ii) a Density is determined according to ASTM D-792.
XCATTMVP-100 is used for five polymerizations. Five aggregations represent two factors (C) with a central point6/C2Consumption and H2ppm), two level designed experiment. H since the ethylene partial pressure and the total reactor pressure of all five sections were kept constant2ppm denotes H2/C2The molar ratio. For the five polymerizations, a gas-phase fluidized-bed reactor was used, having an internal diameter of 0.57m and a bed height of 4.0m, and a fluidized bed composed of polymer particles. Fluidizing gas at 1.8 to 2A speed of 2 ft/sec through the bed. The fluidizing gas leaves the top of the reactor and passes through a recycle gas compressor and heat exchanger before re-entering the reactor below the distribution grid. A constant fluidized bed temperature is maintained by continuously adjusting the water temperature on the shell side of the shell and tube heat exchanger. Gaseous feed streams of ethylene (monomer), nitrogen and hydrogen, and 1-hexene (comonomer) were introduced into the recycle gas line. The reactor was operated at a total pressure of about 2068kPa gauge and vented to a flare (flare) to control the pressure. The individual flow rates of ethylene, nitrogen, hydrogen and 1-hexene were adjusted to maintain the desired target. The concentration of all gases was measured using an on-line gas chromatograph. The ethylene partial pressure was kept constant at 200 psi. The catalyst is fed semi-continuously at a rate to achieve a target polymer production rate in the range of 60 to 75 kg/hr. The fluidized bed is maintained at a constant height by withdrawing a portion of the bed at a rate equal to the rate of product formation. The product is removed semi-continuously through a series of valves into a fixed volume chamber. The nitrogen purge removes a substantial portion of the entrained and dissolved hydrocarbons in the fixed volume chamber. The product is further treated with a small amount of wet nitrogen to deactivate any traces of residual catalyst and/or cocatalyst. The CA-300 feed, commercially available from UnivationTechnologies, LLC, was fed to the reactor at a rate sufficient to produce about 30ppmw in the final product. The polymerization conditions and/or product characteristics are reported in table 1.
XCATTMHP-100 was used for five polymerizations. Five aggregations represent two factors (C) with a central point6/C2Consumption and H2ppm), two level designed experiment. H since the ethylene partial pressure and the total reactor pressure of all five sections were kept constant2ppm denotes H2/C2The molar ratio. For the five polymerizations, a gas-phase fluidized-bed reactor was used, having an internal diameter of 0.35m and a bed height of 2.3m, and a fluidized bed composed of polymer particles. The fluidizing gas is passed through the bed at a velocity of 1.8 to 2.2 feet per second. The fluidizing gas leaves the top of the reactor and passes through a recycle gas compressor and heat exchanger before re-entering the reactor below the distribution grid. By continuously adjusting shell-and-tube heat exchangersThe water temperature on the shell side of the exchanger maintains a constant fluidized bed temperature. Gaseous feed streams of ethylene, nitrogen and hydrogen were introduced into the recycle gas line along with the 1-hexene comonomer. The reactor was operated at a total pressure of about 2413kPa gauge and vented to a flare to control the total pressure. The individual flow rates of ethylene, nitrogen, hydrogen, and 1-hexene were adjusted to maintain the gas composition target. The concentration of all gases was measured using an on-line gas chromatograph. The ethylene partial pressure was kept constant at 200 psi. The catalyst is fed semi-continuously at a rate to achieve a target polymer production rate in the range of 15 to 25 kg/hr. The fluidized bed is maintained at a constant height by withdrawing a portion of the bed at a rate equal to the rate of particulate product formation. The product is removed semi-continuously through a series of valves into a fixed volume chamber. The nitrogen purge removes a substantial portion of the entrained and dissolved hydrocarbons in the fixed volume chamber. After purging, the product is discharged from the fixed volume chamber into the fiber package for collection. The product is further treated with a small amount of a wet nitrogen stream to deactivate any trace amounts of residual catalyst and/or cocatalyst. The polymerization conditions and/or product characteristics are reported in table 2.
TABLE 1
TABLE 2
Based on XCATTMRegression analysis of VP-100 polymerizations 1-5 was used to provide the following equation:
equation 1:
equation 2:
based on XCATTMRegression analysis of HP-100 polymerizations 1-5 was used to provide the following equation:
equation 3:
equation 4:
FIG. 1 shows C generated using equations 1 and 36/C2Flow ratio (lb/lb) to I2Graph of melt index. FIG. 1 illustrates utilizing XCATTMExample 1 of VP-100, a method for adjusting melt index as disclosed herein. FIG. 1 also illustrates utilizing XCATTMComparative example A of HP-100, wherein the concentration of comonomer was reduced.
For example 1 and comparative example A, 0.918g/cm was used3Reducing the concentration of comonomer to provide respectively lower melt indices; while reducing the hydrogen concentration to maintain the predetermined density constant.
As shown in fig. 1, corresponding to a C of about 0.0926/C2The polymerization of the flow ratios provides a
As shown in FIG. 1,
FIG. 1 is a graph illustrating the use of a metallocene complex of formula I (i.e., XCAT)TMVP-100) can advantageously provide that polymers with constant density and lower melt index can be produced by reducing the comonomer concentration. Further advantageously, the graph of fig. 1 illustrates that the comonomer of example 1 is reduced by about 24% compared to the comonomer of comparative example a by about 4%. The improved (i.e., greater) comonomer reduction of example 1 compared to comparative example a may be desirable for many product applications. It may be desirable to use less comonomer for the overall plant economics because, for example, 1-hexene is more expensive than ethylene.
FIG. 2 shows densities (g/cm) generated using equations 1-43) And I2Graph of melt index (dg/min). FIG. 1 illustrates utilizing XCATTMExample 2 of VP-100, a method for adjusting density as disclosed herein. FIG. 2 also illustrates utilizing XCATTMComparative example B of HP-100, wherein the hydrogen concentration was reduced. For example 2 and comparative example B, respective C6/C2The flow ratios were maintained constant at about 0.092lb/lb and 0.065lb/lb, respectively.
As shown in FIG. 2, polymer 240 corresponds to a melt index of about 0.94 dg/min and a melt index of about 0.9176g/cm3(ii) a density of (d); polymer 240 corresponds to about 290ppmv H2And (4) concentration.
For example 2, H2The concentration decreases from polymerization 240 to polymerizations 242, 244, 246, and 248. Polymer 242 corresponds to about 280ppmv H2Concentration, about 0.9173g/cm3And a density of about 0.83 minMelt index in grams/minute; polymer 244 corresponds to about 270ppmv H2The sum of the concentrations was about 0.9169g/cm3And a melt index of about 0.73 dg/min; polymer 246 corresponds to about 260ppmv H2The sum of the concentrations was about 0.9166g/cm3And a melt index of about 0.65 dg/min; polymerization 248 corresponds to about 60ppmv of H2The sum of the concentrations was about 0.9097g/cm3And a melt index of about 0.05 dg/min.
As shown in FIG. 2, polymer 250 corresponds to a melt index of about 0.94 dg/min and a melt index of about 0.9176g/cm3(ii) a density of (d); polymer 250 corresponds to about 105ppmv H2And (4) concentration. For utilizing XCATTMComparative examples B, H of HP-1002The concentration decreased from polymer 250 to polymer 252, which corresponds to a melt index of about 0.60 dg/min and a melt index of about 0.9166g/cm3(ii) a density of (d); polymer 252 corresponds to about 60ppmv H2And (4) concentration. Comparative example B extended to the polymer in region 254, which is practically infeasible because of XCATTMHP-100 generates hydrogen during the polymerization process. Thus, using XCATTMAbout 60ppmv H associated with Polymer 252 at HP-1002The concentration may be considered as the lower limit of the hydrogen concentration.
FIG. 2 is a graph illustrating the use of a metallocene complex of formula I (i.e., XCAT)TMVP-100) can advantageously provide for a process that can be maintained with comonomer consumption (e.g., C)6/C2Flow ratio) while producing a polymer having a reduced density. Further advantageously, the graph of FIG. 2 illustrates maintaining monomer concentration and comonomer concentration (e.g., C)6/C2Flow ratio) can produce a polymer with a reduced melt index. Using metallocene complexes of formula I (e.g. XCAT)TMVP-100) can advantageously provide that polymers having lower densities and/or lower melt indices can be produced by reducing the hydrogen concentration. Since other metallocene complexes (e.g. XCAT) are utilizedTMHP-100) may generate hydrogen during polymerization, so a concentration by reducing the hydrogen (i.e., the hydrogen fed to the reactor) may not be availableTo produce a lower density (e.g., less than about 0.9168g/cm as shown in FIG. 2)3Density) and/or a lower melt index (e.g., a melt index of less than about 0.0.60 dg/min as shown in fig. 2), as shown in the graph of table 2.
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