ZA200605267B - Method for controlling sheeting in gas phase reactors - Google Patents

Description

METHOD FOR CONTROLLING SHEETING IN GAS PHASE REACTORS

TECHNICAL. FIELD

[0001] Embodiments of this invention relage to measuring and controlling static in a gas phase polymer—ization reactor. In particular, embodiments of this invention re=late to monitoring carryover stati .c in new locations in the overall gas phase polymerization re=actor, generally in polymerizatiors utilizing metallocene catalysts, to determine the onset of reactor discontinuity events such as= chunking and sheeting. Embodiments of the invention also reelate to monitoring carryover stat ic in these new locations, to determine the need for additison of an effective amount of cortinuity additives that minimize reactor static activity, and in articular carryover static, and the=xeby preventing or minimizing su ch discontinuity events.

BACKGROUND

[0002] Stmecting and chunking has been =a problem in commercial, gems phase polyolefin production re=actors for many years. The pro blem is characterized by the formation of solid masses of poslymer on the walls of the reactor. These solid masses or peolymer (the sheets) eventually become dislodged from the walls and fall into the reaction Section, where they interfere with fluidization, block the product discharge port, and usually force a reactor shut- down for clezaning, any one of which can be tesrmed “discontinuity event”, which in general is a disruption in the continuous operation of a polymerization reactor. T he terms “sheeting, chunking ardor fouling” while used symonymously herein, may describe different manifestatiors of similar problems, in each ca=se they can lead to a reactor ¢_iscontinuity event.

[0003] T here are at least two distinct forms of sheeting that occur in_ gas phase reactors.

The two forrms (or types) of sheeting are descxribed as wall sheets or dome Sheets, depending on where they aare formed in the reactor. Wall ssheets are formed on the wal3s (generally vertical sections) of the reaction section. Dome sheets are formed much higher in the reactor, on the conical secti on of the dome, or on the hemi-spoherical head on the top of the= reactor (Figure 1).

[0004] VVhen sheeting occurs with Zieglesr-Natta catalysts, it generally~ occurs in the lower "section of thme reactor and is referred to as wall sheeting. Ziegler-Natta cawalysts are capable of forming donme sheets, but the occurrence is rare. But with metallocene catalysts, sheeting can occur in eitlher location or both locations; that is, both wall sheeting ancl dome sheeting can occur. }

SUBSTITUTE SHEET (RULE 26)

~2-

[0005] Dome sheeting has been a particularly troublesome with. metallocene catalyst systems. Typical metallocene compounds are generally described as c=ontaining one or more ligands caapable of bonding to the transitiom metal atom, usually, cycslopentadienyl derived ligands or~ moieties, in combination with a transition metal selected from Group 4, 5 or 6 or from the Lanthanide and actinide series of the Periodic Table of Elements. 0006) One characteristic that makes it difficult to control shee=ting with metallocene catalysts is their unpredictable static tendencies. For instance, EP 0 811 638 A2 describes metallocene catalysts as exhibiting sudden ematic static charge behavior that can appear after long periwods of stable behavior.

J) [0007] As a result of the reactor discontinuity problems associated with using metallocene- catalysts , various techniques have been developed that are said to result in improved operability. For example, various supporting procedures or me thods for producing em metallocene catalyst system with reduced tendencies for fouling ancl better operability haves been di scussed in US Pat. No. 5,283,218, which discloses the prepolymerization of =a 5 metallocene catalyst. US Pat. Nos. 5,332,706 and 5,473,028 disclose za particular technique fo=r forming=, a catalyst by "incipient impregnation.” US Pat. Nos. 5,427,951 and 5,643,847 disclos-e the che=mical bonding of non-coordinatimg anionic activators to =supports. US Pat. No. 5,492,975 discloses polymer bound metallocene catalyst systems. US Pat. No. 5,661,09%5 disclose=s supporting a metallocene cataly’st on a copolymer of an Olefin and an unsaturate=d 0 silane. PCT publication WO 97/06186 Qliscloses removing inorgan_ic and organic impurities after formation of the metallocene catalyst itself. WO 97/1 5602 discloses readily supportabmle metal complexes. WO 97/27224 discloses forming a supported tranmsition metal compound in the pre=sence of an unsaturated organic cormpound having at least one terminal double bond. . [00081 Others have discussed different process modificatiorms for improving reactor 5 continuity with metallocene catalysts ancl conventional Ziegler-Nattka catalysts. For exampmle,

WO S®7/14721 discloses the suppression of fines that can cause sheeting by adding an inert hydrocarbon to the reactor. US Pat. No. 5,627,243 discloses a Qlistributor plate for use in fluidiazed bed gas phase reactors. WO 96/08520 discloses avoiding the introduction o—f a scavemnger into the reactor. US Pat. No. 5,461,123, discloses usimg sound waves to redwuce 0 sheetiang. US Pat. No. 5,066,736, and EP>-A1 0 549 252, disclose thes introduction of an activity retardlier to the reactor to reduce agglomerates. US Pat. No. 5,610,244, discloses feeding mamke- up muonomer directly into the reactor above the bed to avoid fouling and improve polymer quali-ty. US Pat. No. 5,126,414, discloses including an oligomer reemoval system for reducing distributor plate fouling and providing for polymers free of gels. There are various o"ther known methods for improving operability including coating. the polymerization equipment, controlling the polymerization rate, particularly on start-up , and reconfiguring the reamctor design and injecting various agents into the reactor.

[0009] With respect ®o injecting various agents into the re actor, the use of antistatic ag=ents as process “continuity aclditives” appear to hold promise and have been the subject of vamrious publications. For example, EP 0 453 116 Al, discloses the izntroduction of antistatic agernts to the reactor for reducing the amount of sheets and agglom erates. US Pat. No. 4,012 ,574, discloses adding a surfa.ce-active compound having a perflucorocarbon group to the reactor to 0 reduce fouling. WO 96/11961, discloses an antistatic agent for reducing fouling and sheeting in a gas, slurry or liquid pool polymerization process as a c-omponent of a supported catalyst system. US Pat. Nos. 5,034,480 and 5,034,481, disclose a reaction product of a conventional

Ziegler-Natta titanium catalyst with an antistatic agent to produce ultrahigh molecular veveight ethylene polymers. For example, WO 97/46599, disclose=s the use of soluble metall ocene 5 catalysts in a gas phase process utilizing soluble metallocerme catalysts that are fed into a lean zone in a polymerization reactor to produce stereoregulamr polymers. WO 97/4659%9 also discloses that the catalyst feedstream can contain antifoumlants or antistatic agents suach as

ATMER ® 163 (commercially available from ICI Specialty Chemicals, Baltimore, Md.).

[00010] US Pat. No. 5,410,002, discloses usirmg a conventional Zieglemr-Natta 0 titanium/magnesium swpported catalyst system where a selection of antistatic agents are= added directly to the reactor to reduce fouling. The amount -of antistatic agent is described as ] depending on the gran-ulometric distribution of the polymer or of the polymer being formed and one example of the an tistatic agent is ATMER 163, but no method for dynamically adjusting or . optimizing the amount of antistatic agent is disclosed. 5 [00011] US Pat. No. 4,978,722, discloses a methomd for producing a propylerme-alpha olefin block co-polyrmer in which one compound selected from the group consisting of an aromatic carboxylic acid ester, a phosphorous ester, an uns=saturated dicarboxylic acid daiester, a tertiary amine, and ar amide are added to the gas phase of the polymerization reactor wwhereby the formation of low molecular weight polymer is suppre ssed and adhesion of polymeer to the 0 walls of the reactor is prevented. But there is no me=ntion in US Pat. No. 4,978,722 of measuring electrostatic activity nor is there any mention of a method to optimize the level of the compound that is added to prevent adhesion.

[00012] US Pat. No. 5,026,795, discloses the addition of an antistatic agent with a liquid carrier to the polymerization zone in a gas phase polymerization reactor. Pr-eferably, the antistatic agent is mixed with a diluent and introduced into the reactor by a carrier comprising the comonomer. The preferred antistatic agent disclosed is a mixture, which is maarketed under the trademark STADIS® 450 by Octel Starreor and which contains a polysulfone=, a polymeric polyamine, a sulfonic acid, and toluene. The a_mount of antistatic agent is disclossed to be very important. Specifically, there must be sufficient antistatic agent to avoid ad¥hesion of the polymer to the reactor walls, but not so mu«h that the catalyst is poisoned. US Pat. No. 5,026,795 also discloses that the amount of ®he preferred antistatic agent is irm the range of 0 about 0.2 to 5 parts per million by weight (pprmw) of polymer produced; howev—er, no method for optimizing the level of antistatic agent is disclosed based on measurable reactcor conditions.

[00013] EP 0 811 638 A2, which is «discussed above, discloses using a metallocene catalyst and an activating cocatalystin a polyrmerization process in the presence =of an antistatic agent, and also discloses the use of ATMERR 163. EP 0 811 638 A2 also disscloses various 5 methods for introducing the antistatic agent, rmost preferably the antistatic agent is sprayed into the fluidized bed of the reactor. Another rmethod generally disclosed is the addition of an antistatic agent with the supported or liquidk catalyst stream so long as the catalysts are not severely affected or poisoned by the antistatIc agent. EP 0 811 638 A2 incluc®es examples in which the supported catalysts were slurried in mineral oil prior to being inmroduced to the '0 reactor and the antistatic agent was introduced directly to the reactor vewhen using the unsupported catalysts. Static was measurecd in the fluidized bed itself a few= feet above the ) distributor plate. Preferably, the antistatic agent was added intermittently imn response to a change such as a rising level of static electricity. - [00014] Although various methods haave been developed to manage sh_ecting problems with metallocene catalysts and use of continuity additives has been investigasted, the problem persists. One reason the problem persists is that the use of continuity amdditives can be accompanied by decreased catalyst effi ciencies and productivities. Deecreased catalyst efficiencies and catalyst productivities occur where additives injections &are not matched precisely in regards to frequency and/or armount to arrest transient instances of reactor static, which can presage undesirable “reactor disczontinuity events”.

[00015] Another reason sheeting problems with metallocene catalysts persist (and perhaps is the root-cause of the problem) is the lack of advanced warning of s—uch events (Note:

EP 0 811 638 A2 above in paragraph [ 006]). Most sheeting incidents —with metallocene catalysis have occurred with little or no advanced indication by any of the previousRy known and/or used process instruments, including the conventional static probes used heretofore. (Conventional static probes are those probes that are leocated, as discussed hereir, and as discussed in US 4,855,370, % to % of a reactor diameter ambove the top of the distributor plate.)

This lack of indicatiora with conventional instruments by previously available mmeasurable indicators has presente=d a significant challenge in efforts to troubleshoot and ccorrect the sheeting problems (ard the resultant reactor discontinuity) with metallocene catalyzed reactions.

[00016] One of the first descriptions of reactor sheeting was provided in US =4,532,311. 0 This patent was among the first to describe the important discovery that sheeting wih Ziegler-

Natta catalysts is the ressult of static electrification of the —fluid bed. (not sure if it is a_ good idea to characterize the teachings unless it was explicit) A subsequent patent, US 4,855,370, combined the static probe of the ‘311 document with a means to control the level «of static in the reactor. In the casse of US 4,855,370, the means to Control static was water addition to the 5 reactor (in the amount: of 1 to 10 ppm of the ethylene fe-ed). This process has provesn effective for Ziegler-Natta catalysts, but has not been effective for metallocene catalyst r=eactions or reactors. [00017) Undersstanding the causes of sheeting with metallocene catalysts hams for many years been hampered by the lack of suitable instrumentation. In particular, the static probes (so 0 called conventional static probes, located on the wall(ss) of a reactor as noted abowe) used for

Ziegler-Natta catalysts have not been effective for pro=viding warning or notice of sheeting or chunking in metallocene catalyzed reactions and reactors utilizing such reactionss. Wall and dome sheeting witlm metallocene catalysts usually occurs with no prior (or coincident) indication on the con.ventional reactor static probes. Tlhis can be seen in Figure 7, wvhich shows that there was virtually no response on the (convention. al) reactor static probe(s) in a pilot plant prior to the wall sheseting incident with metallocene catalyst, compared to other static probe locations which did sshow a response (i.e. static above z=ero). {00018} Thus. it would be advantageous to Imave a polymerization process utilizing metallocene catalys-ts, the process being capable of operating continuously with enhanced reactor operability defined as the general absence O=f sheeting or chunks that rmight lead to reactor discontinuity events). It would also be high_ly advantageous to have a continuously operating polymeri_zation process having more stalble catalyst productivities and reduced fouling/sheeting termdencies based on readily measuratole reactor conditions such a_s electrostatic activity at points in the re. actor system, which need is answered by embodiments of= the present invention.

SUMMARY

[00019] Among tkae contemplated embodiments eof our invention is a process for monitoring the static ggenerated during polymerization to avoid or minimize reactor discontinuity events com prising: measuring carryover stamtic using one or more of at least one recycle line static probe, =or at least one annular disk probe

[00020] A further embodiment includes a process for introducing at least ore continuity 0 additive into a reactor ssystem in an amount that preve mts or reverses sheeting- of polymer produced by a polymer—ization reaction of at least one. olefin, wherein the poslymerization reaction is conducted ir the reactor system, the reactomr system comprising a Fluidized bed reactor, an entrainment zone, a catalyst feed for introaducing a catalyst systenm capable of producing the polymer, a continuity additive feed for iratroducing the at least ome continuity

S additive independently of the catalyst mixture, a means for monitoring levels of electrostatic activity in the entrainme=nt zone, the process comprising: contacting the at least ore olefin with the catalyst system und_er polymerization conditions in the fluidized bed reactomr; introducing the continuity additive into the reactor system at anytime before, during, or after start of the polymerization reaction_; monitoring the levels of electro- static activity in the entrainment zone; 0 and adjusting the amount of continuity additive introduced into the reactor system to maintain the levels of electrostatic activity in the entrainment zon. e at or near zero. In suckn a process the catalyst system comprisses a metallocene or a conventiormal transition metal cataly=st, the process may be a gas phase process, and the polymer is p-roduced continuously, t=he monomers - comprise ethylene or ethylene and one or more alpha-oleefins. In the process. the catalyst system *S comprises a metalloc=ene catalyst system, wherein the means for measur—ing levels of electrostatic activity ina the entrainment zone comprise ene or more of at least o'ne recycle line static probe, at least orme annular disk probe, at least ones distributor plate static p-robe or at least one upper reactor statzic probe. The at least one cont3nuity additive comprise=s one or more compounds selected f5rom the group consisting of alk-oxylated amines, carboxzylic acid salts, 0 polysulfones, polymer-ic polyamines, sulfonic acids, omr combinations thereof. Or the at least one continuity additive comprises ethoxylated steary® amine, or the at least one continuity additive comprises a luminum stearate, or the at le ast one continuity additive comprises aluminum oleate. Or the at least one continuity add itive comprises a mixtumre of 1 decene-

polysulfone presert in a concentration of 5 to 15 per—cent by weight of the mixture, a reaction product of N-tallo-w-1,3-diaminopropane and epichlosthydrin present in a concemmtration of 5 to 15 percent by weight of the mixture, dodecylbenzene sulfonic acid present in a concentration of to 15 percent by weight of the mixture, and a hydrocarbon solvent in a concenfiration of 60 to 5 88 percent by weight of the mixture. The at leamst one continuity additive is introduced intermittently, an.d/or the at least one continuity additive is introduced as a slurry in a hydrocarbon liquid or as a solution in a hydrocambon liquid. The at least one continuity additive may also be present in the catalyst mixture= that is introduced into the reactor system via the catalyst feed, and the amount of the at least sone continuity additive in tine fluidized bed ) reactor is maintafined at a concentration of 1 to 50 p arts per million, based on the weight of the polymer produce«d in the fluidized bed reactor.

[00021] A further embodiment includes a polymerization proces=ss comprising: polymerizing ethylene and one or more alpha-eolefins in the presence o—f one or more metallocene catemlysts in a gas phase reactor; monitoring electrostatic activity in the gas phase 5 reactor by a m-onitoring means; applying an effective amount of one or —xnore continuity additives to the polymerization process responsive to the monitoring means- measuring said electrostatic activity deviating from at Or near zero, to return the electrostatic activity to at or near zero.

[00022] Another embodiment contemplated is a gas phase polymerization process, 0 wherein electrozstatic activity generated in an entrafnment zone of a gas phase reactor is reduced or eliminated, ccomprising; polymerizing ethylene and one or more a-olefins in the presence of a metallocene catalyst system; measuring entrainmment zone electrostatic activity using one or more of at leasst one recycle line static probe, at Meast one upper bed static perobe, at least one . annular disk st atic probe, or at least one distributor plate static probe, with the proviso that if 5 the electrostatic activity measured by any one or mmore of the probes deviates from zero, one or more continuitzy additives is added to the gas pha se reactor in an effective anmount to reduce or eliminate the deviation from zero.

[00023] Another embodiment contemplated is a gas phase polyrrerization process comprising: p olymerizing cthylene and one or more a-olefins in a gas ploase reactor in the 0 presence of a metallocene catalyst system; mon itoring the electrostatic activity in the reactor the monitorin_g comprising one or more of at least one conventional static probe, at least one recycle line static probe, at least one upper bec static probe, at least one annular disk static probe, at leamst one distributor plate static probe, or combinations the=reof, wherein the oo electrostatic activity measured by at least one of tThe at least one recycle line static pxcobe, the at least one upper bed static probe, the at least one annular disk static probe, or the eat least one distributor plate= static probe is greater than 0.5 nanoamps/cm? different from the electrostatic activity measureed by the conventional static probes

[00024] Another embodiment contemplated is a process for copolymerizing ethylene and one or more a—olefins in a gas phase reactor utildzing a metallocene catalyst, an activator and a support, comprising: combining ethylene and ome or more of 1-butene, 1-hexene, or 1-octenc in the presence= of the metallocene catalyst, the amctivator and the support; monitoring carryover static in the re actor by one or more of at least one recycle line static probe, at least one upper 0 bed static probe, at least one annular disk static probe, or at least one distributomr plate static probe; maintaining the carryover static at or near zero by use of at least one continuity additive selected fromm one or more of alkoxylated amines, carboxylic acid salts, polysulfones, polymeric po lyamines, sulfonic acids or combinations thereof, the at least ore continuity additive prese=nt in the reactor from 10-40 ppm, based on the weight of a polymer produced by 5 the polymeriz=ation.

DESCRIPTEON OF THE DRAWINGS

[00025] Figure 1 shows a schematic draxwing of a typical gas phase reactor.

[00026] Figure 2 shows an example of a conventional reactor static probe. ‘0 [00027] Figure 3 shows an embodiment of the at least one recycle line statiec probe.

[00028] Figure 4 shows an XCAT™ EZ. 100 dome sheeting incident. ] [00029] Figure 5 shows four dome sheeting incidents with XCAT EZ 100. (00030] Figure 6 shows distributor plates static for XCAT EZ 100. : [00031] Figure 7 shows wall sheeting ircidents with XCAT™ HP 100. 5 [00032] Figure 8 shows entrainment swatic for wall sheeting incidents with XCAT HP 100.

[00033] Figure 9 shows skin temperature and additive flow rate for XCAT™ HP100.

[00034] Figure 10 shows the static profile and additive flow rate for XCA™T HP 100.

[00035] Figure 11 shows skin temperature plot for Octastat 3000 ® with >XCAT HP 100.

[00036] Figure 12 shows a static profil e using Octastat 3000 ® with XCA_THP 100.

DESCRIETION

[00037] We have surprisingly dis-covered that by changing thee location of static activity actually measured (current per unit area is actually measured) ¥n a polymerization reactor, we can detect and therefore prevent the onset of reactor discontimmuity events, such as sheeting osr chunking, especially for polymer—izations with metallocene catalysts. Alternatively, we can stzabilize or eliminate reactor disconti nuity events, defined herein ass sheeting, chunking or foulingg. In particular, we have discovere=d that for gas phase polymemrizations, significant static chamrging results from frictional con tact between entrained catalyst particles and/or entrained resin particles (by entrained particles we intend those particles tat are not contained 0 in the dense phase zone of the reactor, and are therefore outside the fluid bead, as conventionally understood) against the walls and other met al components in the reactor recycle system. We have termed this static “carryover static”. The persistent problem kno=wn for metallocene catalysts (where sheeting and chunking hass not been known to be foretold by conventional reactor staatic probes) is now solved with the discovery of, and measuremert of, carryover static 5 in embodiments of the present invention. This carryover static can be m. onitored in locations discussed herein, and controlled using conwentional means or techniques, which in turn will reduce, prevent or eliminate sheeting, chunk -ing or fouling.

[00038] Frictional electrification (or triboelectrification) of solid particles is well known ir= the literature. In general, static ch arging can result whenever tweo dissimilar materials 0 are broumght into close contact. The d3ssimilar materials can be t=wo different metals (conducteors), two different insulators (a classsic example being wool again_st an amber rod), or a conductor and an insulator. In the case of a gas phase polymerization reactor, static charging results fi-om the frictional contact of polyethylene resin and catalyst particles (both insulators) - against tlhe carbon steel of the reactor wall (= conductor). 5 [00039] The basic driving force for frictional electrification is am difference in the two materials affinity for electrons. The mamerial with the greater affinitwy gains electrons and becomess negatively charged, and the other Booses electrons and becomes gpositively charged. In collisiomms of solid particles with the walls, piping or other metal parts of a polymerization reactor, the amount of charge transferred diepends on the electrical prope=tties of the metal and 0 the particles, the degree of contact, the suarface roughness, and other factors. Studies in the field of pneumatic conveying have indicated that triboelectrification of solid particles is also sensitive to the velocity of the conveying gaas.

[00040] The amount of charge developed is also sensitive to any cormtamination that may exist on the surface of the reactor walls or other metal parts that come into contact with the solid particles. Charging is highly dependant on tkne characteristics of any ressin coating that may exist of the imternal surfaces of the reactor. In general, static charging is re duced when the walls are (desirab ly) coated with polyethylene of high electrical resistance.

[00041] It is known that electrostatic acti vity in polymerization reac tor systems can be correlated to the formation of polymer sheets and/or fouling of the reactor Wy the polymer, and a resultant decrease or interruption in polmymer production (a discomntinuity event).

Detection of and discussion of this electrostatic activity has generally been limmited to the fluid 0 bed portion of the reactor, i.e. the dense portion of thhe bed, generally above the distributor plate up to approximately % of a reactor diameter distanece above the distributor plate, or from % to 3 of a reactor diameter above the distributor plate. However, for metallocene catalysts in gas phase reactions, conventional, previously knowr static probes, often ares not useful in predicting a reactor discontinuity event. Many tinmes in a metallocene cataly zed reaction the 5 conventional static probes show little or no electro static activity even during =a sheeting event.

Specifically, wh ile one or more static probes in the entrainment zone of tlhe reactor show electrostatic acti vity, which we now know is pre dictive of reactor discontirwuity events, the conventional static probes frequently show little osr no electrostatic activity. These problems are also known to vary over time during the course of the polymer producation process. In 0 embodiments o=Xf the present invention, the abi lity to monitor electrostatic charging (as measured by ciamrent/unit area) and to do so ir the entrainment zone of the reactor not _ previously used to detect static charge, allows for dynamically adjusting thme amount of the continuity additive that is used. That is, the amourt of continuity additive is amdjusted based on - the level of electrostatic activity in the reactor sysstem as detected by one or more of the non- )5 conventional, emtrainment zone static probes. The terms electrostatic activity, electrostatic charging, and static, are used interchangeably herein. When electrostatic activity in the entrainment zorme is discussed, it is also represented by “carryover static”

[00042] The entrainment zone is defined as any area in a reactor system above or below the dens e phase zone of the reactor systemm. Fluidization vessels with a bubbling bed comprise two zones, a dense bubbling phase with an upper surface separating it from a lean or dispersed phases. The portion of the vessel betweemn the (upper) surface of the =dense bed and the exiting gas strezam (to the recycle system) is called “freeboard”. Therefore=, the entrainment zone comprisess the freeboard, the cycle (re cycle) gas system (inclu ding piping and compressorsa/coolers) and the bottom of the reactor up to the top -of the distributor plate.

Electrostatic= activity measured anywhere in time entrainment zone is teermed herein “carryover static”, and amas such, is differentiated from the electrostatic activity mezasured by a conventiormal static probe or probes in the fluid bed.

[00043] We have surprisingly discovered that the electrostatic activity (carryov=er static) meas—ured above the “at or near zero” level (as defined herein) on the carryover particles in the entrainment zone correlates with sheeti mg, chunking or the onsset of same in a polymer reaction sysstem and is a more correlatable indicator of sheeting or a discontinuity event thoan electrostatics activity measured by one or more “conventional” stattic probes. In addition, 0 monitoring electrostatic activity of the carryover particles in the ennmrainment zone has be=en found to perovide reactor parameters by wimich the amount of comntinuity additive can be dynamicallws adjusted and an optimum level Obtained to reduce or eliminate the discontinuity event.

[00044] If the level of electrostatic activity in the entrai nment zone increases in 5 magnitude during the course of the reaction, the amount of continuity additive in the reactor system can be adjusted accordingly as describ ed further herein.

Static Prolibes

[00045] The static probes describe d herein as being in the entrainment zone include ‘0 one or mo re of at least one recycle line probe; at least one annula_r disk probe; at least ‘one distributor plate static probe; or at least one upper reactor static probes, this latter will be outsside } or above t=he V4 to % reactor diameter height above the distributor plate of the conventicnal probe or perobes. These probes may be used to determine entrainmernt static either individu ally : or with on_e or more additional probes from each group mentioned at>ove. Figure 1 shows scome of the gen eral locations of the instruments used in embodiments of t=he present invention. The instruments include a conventional static detector or detectors in th e fluid bed (“conventisonal reactor stamtic probe”) as described herein.

[00046] Figure 2 shows an exam ple of a conventional mreactor static probe. This probe or porobes measure the electric current that flows from a probee tip as a result of particle 0 impacts (boy the catalyst and/or resin). The rneasured current (per umnit area) from the prob e tip provides xn estimate of the charge transfer that is occurring on the reactor wall as a whole. The probe tipzs effectively represent pieces of the reactor wall that Imave been instrumente=d to measure ~the charge flow. The probe tips for these detectors ass well as all other pr-obes discussed herein, ma=y be made of any conductor, inchmding carbon steel, iron, =stainless steel, titanium, platinum, nickel, Monel® alloy, copper, aluminum, or they may be bm -metallic with one metal forming a core the other forming a skin or veneer. Further description of conventional static probes is provided in US 6,008,662.

[00047] Typicaal current levels measured with the conventional reactor protoes range from + 0.1-10, or 0.1—8, or 0.1 ~ 6, or + 0.1-4, or + 01-2 nanoamps/cm®. As v=vith all current measurements discus-sed herein, these values will generally be averages over time periods also discussed herein, also these may represent root mean squared values (RMS), in which case they would all be positives values. However, most often, in reactors utilizing metallomcene catalysts, 0 the conventional reaector probes will register at or near zero during the beginninmg of or middle of a sheeting inciderat. By at or near zero, we intend for either the conventional static reactor probe as well as the probes in the entrainment zone, to beavalueof $+ 0.5, or +03, ors 0.1,or<+005,or <+003,or<=* 001,or£+ 0.001 0r0 nanoamps/cm’. “For example, a measured value of -O.4 would be “less than” “+ 0.5”, ass would a measured value of +0.4. 5 [00048] As mnoted elsewhere herein, the conventional static probe ma=y register at or near zero static or current (as defined herein), while &at least one other static pmrobe in at least one location in the entrainment zone, may register static activity or current Inigher than that measured by the co mventional static probe (this latter may most often be at or™ near zero with metallocene catalys-t). In this event, where the diffemrence between the curremnt measured by '0 conventional static probe and the current measured by one or more other (neon-conventional static probes) is = +=0.1, or 2 £ 0.3,orz+0.5 nanoampps/cm?, or greater, action will be taken to . reduce or eliminate the static charge in being detectecd at one or more of the entrainment zone probes. Such actions may be addition of at least one continuity additive (or a ne=t increase in the : presence in the reactor of at least one continuity add itive), or a reduction in She catalyst feed }5 rate, or a reductiom in the gas throughput velocity, or combinations thereof. These actions constitute means for maintaining, reducing or eliminating carryover static and: reactor static at or near zero.

Recycle Line Static Probe

[00049] The at least one recycle line static p-robe, may be located in_ any part of the recycle line from the inlet of the recycle line at the topp of the reactor to the outlet of the recycle line into the bottormn of the reactor. This will include £rom the recycle line inlem at the top of the reactor to the cooler or compressor (which may be interchanged spatially with one another),

between the cooler and co mpressor, after the cooler oor compressor, betwee=n the cooler or compressor and the recycle line outlet at the bottom of time reactor. With the at “least one recycle 1 ine static probe, and we contemplate 1, 2, 3, 4, 5,6, 7, 8, 9, 10 or more of tHhese recycle line sstatic probes in one or more= locations.

[00050] Figure 3 sho ws an embodiment of the at Beast one recycle line sstatic probe. The robe tip in this embodiment may be a carbon steel rod «(or other materials as discussed herein) 2and may extend approximately to the center of the recycBe line. Further, the at least one recycle

Mine probe may be located zat any angle with or perpendicular to, the recycle li.ne wall. Further, &the at least one recycle line= probe may extend into the reecycle line from 0.1-0-9D, or 0.2-0.8D, 0 or 0.3-0.7D, or 0.4-0.6D, or 0.5D, where D is the insside diameter of the recycle line. As mecycle gas and entrained solid particles (resin and/or catalyst/support particles) flow past the probe, some of the solid particles strike the rod and transfer charge. Current from the at least -one recycle line static protoe may be + 0 - 50 nanoamp s/em?, or + 0.01-25, o=r + 0.01-20, or + 0.1-15, or + 0.1-10, or += 0.1-7.5, or % 0.1-5.0, or == 0.1-2.5, or + 0.1-B 5, or £ 0.1-1.0 5 nanoamps/cm’.

Annular Disk Static Protoe

[00051] The at least one annular disk static proltoe may be located in aany position on or horizontal to the annular «disk that provides access to the flowing stream of gas, and/or liquids and/or entrained solid particles that pass (at relatively high speed) through thes annular opening.

The tip of the probe may project into the annular operning for a distance of 0.1-0.9D, or 0.2- ) 0.8D, or 0.3-0.7D, or 0.4-€.6D, or 0.5D, where D is the= inside diameter of the= annular disk. We . contemplate 1,2,3,4,5,6,7,8,9, 10 or more of these annular disk static prosbes. The probe tip . must be mounted by insul=ating material so as to prevent electrical contact bet—ween the probe tip and the metal surfaces ofS the annulus (and the reactoer walls). Current fromm the at least one annular disk static probe mmay be + 0 - 50 nanoamps/cmm?, or + 0.01-25, or = 0.01-20, or + 0.1- 15, or = 0.1-10, or * 0.1-7.5, or = 0.1-5.0, or =% 0.1-2.5, or * 0.1- 1.5, or + 0.1-1.0 nanoamps/cm?®.

Upper Bed Static Probe

[00052] The at leasst one upper bed static probe —may be located higher in the reactor than the upper limit of a conve=ntional static probe (a distanece above the distributowr plate equal to 3/4 times the reactor diametesr) or generally at least a distaance equal to 0.8, or 0 .9, or 1.0 times the diameter of the reactor and above, and up to the point wheres the vertical walls of the reactor meet the conical section of the reactor. We contemplate 1,2, 3,4, 5,6, 7, 8,9, 10 or =more of these upper bed static probes. Current from the at least one upper bed static probe may be +0 - 50 nanoamps/em? or + 0.01-25, or + 0.01-20, or + 0.1-15, om + 0.1-10, or 0.1-7.5, o-r = 0.1- 5.0,o0r%0.1-2.5, or + 0.1-1.5, or + 0.1-1.0 nanoamps/cm>.

Distributor Plate Static Probes

[00053] The at least one= distributor plate static probe=, also referred to as a disstributor plate cap, represents another means of measuring the carryover static. The at least one 0 distributor plate probe compri ses a metal cap placed above= one or more of the hole=s in the distributor plate. The caps aree insulated from the plate andi connected to a current rmeter by means of an electrical conduit. The at least one probe me asures current transfer dume to the impact of catalyst and/or resi n fines on the metal cap or ecaps. The distributor plamte static probes (caps) may be constructed of carbon steel or othe=r conductors, as noted a bove, to 'S simulate the charge transfer that occurs with all of the other (non-instrumented) capms on the distributor plate. Ideally, thesse distributor plate probes (camps) are constructed from whe same material as the distributor plate and caps. Additional detailss of a distributor plate static probe useful for measuring carryoveer static are provided in US Publication 20040132931, poublished

July 8, 2004, entitled “Static Measurement and Detection in a Gas Phase Polyethylene 0 Reactor”, filed December 26, 2002. We contemplate 1,2,3, 4,5,6,7,8,9,10 or more of these distributor plate static probes. Current measured in the at le=ast one distributor plate pmrobe may . range from += 0 - 50 nanoampos/cm’ or = 0.01-25, or + 0.01 -20, or + 0.1-15, or + 0.1 -10, or 0.1-7.5,0or£0.1-5.0, or + 0.1=2.5, or + 0.1-1.5,0r+ 0.1-1.0 ranoamps/cm?, - [00054] Any one of these static probes in any locastion in the entrainment zZzZone may > 5 function as the static probe thhat is determinative of the begzinning of or existence of a reactor discontinuity event, or one or more in each location (rec ycle line, annular disk, vapper bed and/or distributor plate static probes) may be used in conju_nction with one or more in another location to be so determinati—ve. The static probes may also function separately, that is, if one probe in one location beginss to register static activity act:ion may be taken (as noted herein below) to reduce or eliminate the charge by introduction of continuity additive or im the case where one or more continuity additives are already in the reactor, for instance due to being fed with the catalyst, then additional continuity additives may We added, generally through another feed than the catalyst feed..

VWVO0 2005/068507 PCT/US2004/041. 988 [000-55] Means for monit-oring electrostatic activity in tlhe reactor system are pro vided by staticc probes as known in the art or described herein. Such_ static probes include a metallic prob e tip, one or more signal wires, an electrical feed-throumgh, and a measuring instrument.

The probe tip may comprise a cylindrical rod, but could be any cross sectional forrm such as square, rectangular, triangular, or oblong. With respect to material, the probe tip ma_y be any conductor, as discussed hereinm. With respect to the signal v=vires, any conventional —insulated wire may be used. With respect to the electrical feed-through, any suitable feed-throug lh may be usedl as long as it provides tkne necessary electrical isolation from ground (and thee reactor wall s), and provides the required pressure seal to prevent leak—age of high pressure reac=tor gases 0 from the reactor. Suitable ele=ctrical feed-throughs are available commercially frorm Conax

Buffalo Corp. and other supplisers.

[0056] With respect to monitoring the readings from the static probes, any irstrument or d_évice capable of measuringg the flow of current from the probe tip to ground may~ be used.

Suitable instruments include amn ammeter, a picoammeter (a nigh sensitivity ammeter)s, a multi- 5 meteer, or electrometer. The fl ow of current may also be de=termined monitored indirectly by meansuring the voltage generated by the current in passing thr-ough a series resistor. Tine current in this case would be determired from the measured voltage= by through Ohm’s Law, I = V/R, where 1 is the current (in ampaeres), V is the measured voltag=e (in volts) and R is the -xesistance (in Ohms). As indicated in US 6,008,662, the value of the se=ries resistor may be fromm | ohm to 0 4x 10! ohms, without substartially affecting the value of thes current reading obtained.

Me=thods of Processing Current Level

[00057] Those of skill in the art will recognize that there may be many methods of promcessing the current signals from the static probes. These= methods include simple= weighted 5 ave=raging, with periods of aweraging from 10 milliseconds to 10 hours, or 10 secconds to 10 hours, or 30 seconds to 5 hours, or 1 minute to 1 hour, or 1 rninute to % hour, or 1 mmnute to 10 mimnutes. Additionally or altesmatively, the signal may be processed to provide a root mean squared (RMS) derivative of the basic current signal, a staradard deviation of the bas=sic current sigznal, an absolute value of thhe basic current signal, or an amverage of the absolute vaalue of the bassic current signal (using the averaging periods described a_bove).

Con tinuity Additive

[00058] When one or more of the static probes discussed immediat-ely above begin to regisster static activity above or below zero, (defined as being respectively above or below “at or n ear zero”) measures should be taken to keep the level low or to returr the level of static

S actiwity to at or near zero, which we have shown will prevent, reduce o-r eliminate reactor continuity events. The measures contemplated include addition of one ©r more continuity additives. Such addition may have the effect of raising the level of continmuiity additive in the reactor if a certain level is already present. The total amount of continuity a dditive or additives to b € present in the reactor will generally not exceed 250 or 200, or 150, or M25 or 100 or 90, or 0 80, or 70, or 60, or 50, or 40, or 30, or 20 or 10 ppm (parts per million by weight of polymer beirag produced) and/or the amount of continuity additive will be zero, or Sreater than 1, or 3, or S,or 7, or 10, or 12, or 14, or 15, or 17, or 20 ppm based on the weight of polymer being prociuced (usually expressed as pounds or kilograms per unit of time). Any of these lower limits are combinable with any upper limit. These amounts of continuity a-dditive contemplate one, two, three, four or more continuity additives, the total amount of cene or two or more comtinuity additives in the reactor will be understood to be additive withm the total disclosed immediately above from any source. The continuity additive can be added directly to the reactor through a dedicated feed line, and/or added to any convenient feed stream, including the ethylene feed stream, the comonomer feed stream, the catalyst feed line, or the recycle line. If '0 mo re than one continuity additive is used, each one may be added to the= reactor as separate fee d streams, or as any combination of separate feed streams or mixtur-es. The manner in . wh. ich the continuity additives are added to the reactor is not import=ant, so long as the adclitive(s) are well dispersed within the fluidized bed, and that thheir feed rates (or : corcentrations) are regulated in a manner to provide minimum levels o=f carryover static as '5 disscussed supra. 100059] We contemplate that thie total amount of continuity additive discussed im_ mediately above can include continuity” additive from any source, such a_s that added with the catalyst, that added in a dedicated continuity additive line, that conta ined in any recycle material, or combinations thereof. In one embodiment, a portion of the continuity additive(s) would be added to the reactor as a preventative measure before any measurable electrostatic ac tivity, in such case, when one or more static probes register static acti~vity above the “at or ne ar zero” level, the continuity additive will be increased to return the one or more probes registering static activity, back to at or near zero.

[©@0060] It is also within tThe scope of embodiments of the present invention to introcjuce at least one continuity additive in the catalyst mixture, inject the ¢ atalyst mixture (containirg at lesast one continuity additive) int_o the reactor system, and additionzally or altematively introduce at least one continuity additive #nto the reactor system via a dedicated continuity additive feed line independent of the catalyst- mixture, so that a sufficient con centration of the at least: one continuity additive is introducec into the reactor to prevent or elimminate a reactor discontiruity event. Either of these feed =schemes or both together may toe employed. The contirnuity additive in the catalyst/continuiity additive mixture and the continuity additive added via the separate continuity additive feecq line, may be the same or differermt. 0 [©0061] Determination off optimal continuity additive feed rate to the reactor systeem is evidenced by a value of the camrryover static at or near zero as defined herein. For exarmple, afier stabilizing the carryover sstatic reading in the reactor, if additional (i.e. higher) leve=Is of continuity additive are added, &and if one or more static probes im the entrainment zone owf the reactor shows an increase in maagnitude of static reading, this is a qualitative indication theat the 5 optimum continuity level has een exceeded. In this event, thes levels of continuity additive should be lowered until stability of the static activity (as incicated by relatively corastant readings of static activity in tthe one or more static probes) is again achieved, or the static activity is lowered to near zer-o or regains zero. Thus, dynami-cally adjusting the amoumnt of continuity additive to reach aman optimum concentration range 3s desirable and is within the practice of embodiments of the present invention. By optimum concentration we intend Ierein an effective amount. Therefore, an effective amount of at least one continuity additive i_s that ) amount that reduces, eliminates or achieves stability in electrostatic charge as measured bey one or more static probes. Thus, as noted herein, if too much continuity additive is amdded, electrostatic charge will reappear; such an amount of continui_ty additive will be defirned as outside an effective amount.

[00062] Suitable continmuity additives for use in the pres ent invention comprise One or more compounds selected fimom alkoxylated amines, carboxxylic acid salts, polysul_fones, polymeric polyamines, and sul fonic acids.

[00063] The continuity additive may comprise ethoxylated stearyl amine. Ethox—ylated stearyl amine that is commercially available from ICI and its =affiliates, is supplied uncer the trademark ATMER 163 and another that is commercially awailable from Witco Cheemical

Company is supplied under the trademark AS 990.

[00064] Other suitable continuity additives iriclude aluminum stearate and aliaminum oleate. Still other suitable continuity additives are supplied commercially under the traciemarks

OCTASTAT aand STADIS (these are believed to be the same or similar chemical sutostance) and/or are described in US Pat. No. 5,026,795 and are available from Octel Starreon.

[00065] In another embodiment, the continuit®y additive may be a mixture of 2 «or more of the above Cliscussed continuity additives. Such mnixtures may include: alkoxylated amines and carboxylic acid salts; or alkoxylated amines anc polysulfones; or alkoxylated amines and polymeric pol=vamines; or alkoxylated amines and swilfonic acids; or carboxylic acid ssalts and polysulfones; =or carboxylic acid salts and polymeric polyamines; or carboxylic acid s=alts and 0 sulfonic acidsz or polysulfones and polymeric polyammines; or polysulfones and sulfondc acids; or polymeric polyamines and sulfonic acids. Additio nally, we contemplate alkoxylated amines, carboxylic acid salts and polysulfones; or alkoxy-lated amines, polymeric polyamines and sulfonic acids= or carboxylic acid salts, polysulfoness and polymeric polyamines; or ca_rboxylic acid salts, su lfonic acids and polysulfones; alkox ylated amines, carboxylic acid s-alts and 5 polymeric polyamines; alkoxylated amines, carboxylic acid salts and sulfoniec acids; alkoxylated amines, polysulfones and sulfonic acids; alkoxylated amines, peolymeric polyamines znd polysulfones; polysulfones, pol ymeric polyamines and sulfonic acids; carboxylic acid salts, polymeric polyamines and sull fonic acids. Combinations of four— or more of these conti_nuity additives are also contemplated. These combinations may be combined at '0 ratios of fromm 10:90 to 90:10, or 25:75 to 75:25, or 40:60 to 60:40, or 50:50, or in thee case of three continu ity additives, 10:10:80 to 80:10:10 ox 10:80:10. The absolute amount of these ) continuity adclitives is as noted above.

[00066] Another continuity additive for use in embodiments of the present ®|nvention - comprises a mmixture of 1 decene-polysulfone present in a concentration of 5 - 15 percent by weight of the mixture, a reaction product of N-tallo ‘w-1,3-diaminopropane and epichlorohydrin present in a concentration of 5 - 15 percent by wei ght of the mixture, dodecylbenzen_esulfonic acid present in a concentration of 5 - 15 percent by weight of the mixture, and a hydrocarbon solvent in a concentration of 60 - 88 percent by weight of the mixture, this mixture is commercially available from Octel Starreon and its affiliates under the trademark OC™TASTAT 3000 (which may also be available as STADIS 450) or OCTASTAT 2000 (which maay also be available as SSTADIS 425), each of which may have a different percentage makeup than that discussed immmediately above.

[00067] If a combination of continuity additives is used, the total present in the reactor will be as noted above.

Catalysts

[00068] All polymerization catalysts including conventional transition metal catalysts and metallocene catalysts or combinations thereof, are suitable for use in embodiments of the processes of the present invention. Also contemplated are catalysts such as A.ICl,, cobalt, iron, palladium, chromium/chromium oxide or “Phillips” catalysts. The following is a non-limiting discussion of the various polymerization catalysts useful in the invention. 0

General Definitions

[00069] As used herein, the phrase “catalyst system” includes at least one “catalyst component” and at least one “activator”, alternately at least one cocatalyst. The catalyst system 5 may also include other components, such as supports, and is not limitexd to the catalyst component and/or activator alone or in combination. The catalyst system may include any number of catalyst components in any combination as described herein, as well as any activator in any combination as described herein.

[00070] As used herein, the phrase “catalyst compound” includes arxy compound that, '0 once appropriately activated, is capable of catalyzing the polymerization or oligomerization of olefins, the catalyst compound comprising at least one Group 3 to Group 12 atom, and optionally at least one leaving group bound thereto. {00071} As used herein, the phrase "leaving group” refers to one or more chemical moieties bound to the metal center of the catalyst component that can be abstracted from the catalyst component by an activator, thus producing the species active towards olefin polymerization or oligomerization. The activator is described further below.

[00072] As used herein, in reference to Periodic Table "Groups” of Elements, the “new” numbering scheme for the Periodic Table Groups are used as in the CIRC HANDBOOK OF

CHEMISTRY AND PHYSICS (David R. Lide ed., CRC Press 81% ed. 2000).

[00073] As used herein, a “hydrocarbyl” includes aliphatic, cyclic, olefinic, acetylenic and aromatic radicals (i.e., hydrocarbon radicals) comprising hydrogen and carbon that are deficient by one hydrogen. A “hydrocarbylene” is deficient by two hydrogens.

[00074] As used herein, the phrase “hete=roatom™ includes any atom other than carbon and hydrogem that can be bound to carbon. A “kheteroatom-containing group™’ is a hydrocarbon radical that c=ontains a heteroatom and may contain one or more of the same or different heteroatoms. In one embodiment, a heteroattom-containing group is a lmydrocarbyl group containing frcom 1 to 3 atoms selected from the: group consisting of boron, &aluminum, silicon, germanium, ritrogen, phosphorous, oxygen and. sulfur. Non-limiting examp Iles of heteroatom- containing gmroups include radicals of imines, amines, oxides, phosphiness, ethers, ketones, oxoazolines Ineterocyclics, oxazolines, and thioe thers.

[00075] As used herein, “heterocyclic” re=fers to ring systems having za carbon backbone 0 that comprisee from 1 to 3 atoms selected from the group consisting of boron, aluminum, silicon, germanium, nitrogen, phosphorous, oxygen and sulfur, unless thes heteroatom (non carbon atom)s is described. '

[00076] As used herein, an ‘““alkylcarboxylate”, “arylcamrboxylate”, and “alkylarylcar—boxylate” is an alkyl, aryl, and al kylaryl, respectively, that po=ssesses a carboxyl 5 group inany position. Examples include CeHsCH,C(0)O, CH3C(0)O, ete.

[00077] As used herein, the term “substituted” means that the group following that term possesses at least one moiety in place of one or more hydrogens in any possition, the moieties selected fromm such groups as halogen radicals (for example, Cl, F, Br), hydroxyl groups, carbonyl groups, carboxyl groups, amine gro-ups, phosphine groups, alkomxy groups, phenyl 30 groups, napknthyl groups, C) to Cyo alkyl groups, C, to Co alkenyl groups. and combinations thereof. Exzamples of substituted alkyls and arwyls includes, but are not limit-ed to, acyl radicals, ] alkylamino mradicals, alkoxy radicals, aryloxy radicals, alkylthio radicals, diamlkylamino radicals, alkoxycarbownyl radicals, aryloxycarbonyl raciicals, carbomoyl radicals, salkyl- and dialkyl- : carbamoyl! radicals, acyloxy radicals, acylamirmo radicals, arylamino radicalss, and combinations thereof.

[00078] Unless stated otherwise, no e=mbodiment of the present —invention is herein limited to ®the oxidation state of the metal atom “M” as defined belov=v in the individual descriptionss and examples that follow.

Metallocen e Catalyst Component

[00079] The catalyst system useful in embodiments of the present fnvention include at least one metallocene catalyst component as described herein. Metallocene catalyst compounds are generally described throughowit in, for example, 1 & 2 MBETALLOCENE-BASED

WC 2005/068507 PCT/US2004/041988

PoLYORLEFINS (John Scheirs & W. Kamirmsky eds., John Wiley & Sons... Ltd. 2000); G.G. Hlatky in 181 - COORDINATION CHEM. REV. 243-2296 (1999) and in particular, for use in the synthesis of polyethylene in 1 METALLOCENE-BASEED POLYOLEFINS 261-377 (24000). The metallocene catalyst compounds as described hereein include “half sandwichw” and “full sandwich™’ compowunds having one or more Cp ligands (cyclopentadienyl =and ligands isolobal to cyclopesntadienyl) bound to at least one Group 3 to Group 12 metal atom, and one or mores leaving group(s) bound to the at least ome metal atom. Hereinafter, sthese compounds will bee referreed to as “metallocenes” or “metallocene catalyst components”. The metallocene catalysst compo nent is supported on a support ma-terial in an embodiment, and mmay be supported with o-r1 0 withoust another catalyst component. [00080®] The Cp ligands are one =or more rings or ring systenm(s), at least a portion o=f which includes n-bonded systems, such as cycloalkadienyl ligands an-d heterocyclic analogues.

The rimng(s) or ring system(s) typically scomprise atoms selected frome the group consisting coef

Groupss 13 to 16 atoms, or the atoms thzat make up the Cp ligands are selected from the group 5 consisting of carbon, nitrogen, oxygen. silicon, sulfur, phosphorouss, germanium, boron an d alumiraum and combinations thereof, <wherein carbon makes up at least 50% of the ring membeers. Or the Cp ligand(s) are selected from the group cons isting of substituted an.d unsubsstituted cyclopentadienyl ligands and ligands isolobal to cyclowpentadienyl, non-limitinag examples of which include cyclopentadlienyl, indenyl, fluorenyl and other structures. Further non-limiting examples of such ligandss include cyclopentadienyl, c=yclopentaphenanthreney~1, indense/l, benzindenyl, fluore nyl, octahydrofluorenyl cyclooctatetraeny=1, ] cyclopoentacyclododecene, phenanthrirmdenyl, 3,4-benzofluorenyl, 9-phenylfluorenyl, 8-F1- cyclopoent[a]acenaphthylenyl, 7H-dibermzofluorenyl, indeno[1,2-9]an-threne, thiophenoindenyl, : thioptnenofluorenyl, hydrogenated versions thereof (e.g, 4,5,6,7-tetrahydroindenyl, or “H,Ined”), substituted versions thereof, aand heterocyclic versions there=of.

Grouryp 15-containing Catalyst Compoenent [0008-1] One aspect of the prese nt invention includes the use= of so called “Group 1 5- contafining” catalyst components as desscribed herein as a desirable ecatalyst component, eithmer 30 alone or for use with a metallocene= or other olefin polymerization catalyst componernt.

Genemrally, “Group 15-containing catalyst components”, as referred to herein, include Groups 3 to Greoup 12 metal complexes, wherein. the metal is 2 to 8 coordinat-e, the coordinating moie=ty or moieties including at least two Gro-up 15 atoms, and up to four Group 15 atoms. In ome embodiment, tthe Group 15-containing catalyst cormponent is a complex of a Gmroup 4 metal and from one to fowur ligands such that the Group 4 m etal is at least 2 coordinate, the coordinating moiety or moieties including at least two nitro gens. Representative Groump 15-containing compounds are= disclosed in, for example, WO 99~01460; EP Al 0 893 454, EP Al 0 894 005;

US 5,318,935; US 5,889,128 US 6,333,389 B2 anc US 6,271,325 Bl.

[00082] In one embodiment, the Group 1 5-containing catalyst compeonents useful in embodiments ©f the present invention include (Group 4 imino-phenol complexes, Group 4 bis(amide) complexes, and Group 4 pyridyl-amiade complexes that are activ e towards olefin polymerizatiom to any extent. 0

Activator .

[00083] As used herein, the term "activator" is defined to be ary compound or combination off compounds, supported or unsupported, which can activate a si.ngle-site catalyst compound (e.=., metallocenes, Group 15-contain-ing catalysts), such as by creating a cationic 5 species from tthe catalyst component. Typically. this involves the abstractiomsn of at least one leaving group (X group in the formulas/structuress above) from the metal center of the catalyst component. ~The catalyst components of embodiments of the present in vention are thus activated towa rds olefin polymerization using suc-h activators. Embodiments «of such activators include Lewis. acids such as cyclic or oligomeric poly(hydrocarbylaluminurm oxides) and so 30 called non-c-oordinating activators (“NCA”D) (alternately, “jonizing activators” or “stoichiometri ¢ activators”), or any other compeound that can convert a neutral metallocene ] catalyst component to a metallocene cation that iss active with respect to olefin_ polymerization.

[00084] It is within the scope of this in vention to use Lewis acids swuch as alumoxane ‘ (e.g., “MAO’™), modified alumoxane (e.g, “TOABAO”), and alkylaluminurn compounds as activators, armd/or ionizing activators (neutral or ionic) such as tri (n—butyl)ammonium tetrakis(penta®luorophenyl)boron and/or a trispesrftuorophenyl boron metall oid precursors to activate metallocenes described herein. MAO and other aluminum-based asctivators are well known in thes art. Ionizing activators are well known in the art and are described by, for example, Eugzene You-Xian Chen & Tobin J. Marks, Cocatalysts for Metal"-Catalyzed Olefin

Polymerization: Activators, Activation Processe=s, and Structure-Activity Readationships 100(4)

CHEMICAL REEVIEWS 1391-1434 (2000). The ac-tivators may be associated vmvith or bound to a support, eithexr in association with the catalyst ceomponent (e.g., metallocene”) or separate from the catalyst component, such as described by Gregory G. Hlatky, Heterogeneous Single-Si te

Catalysts for Olefin Polymerizatiorz 100(4) CHEMICAL REVIEWS 13 47-1374 (2000).

Ziegpler-Natta Catalyst Component [00WDsS) The catalyst cormposition may comprise a catallyst component, which is (eor incliudes) a non-metallocene compound. In an embodiment, the c=atalyst component comprisees a Zi egler-Natta catalyst compound, such as disclosed in ZIEGLER CATALYSTS 363-386 (G. F ink,

R. ™Mulhaupt and HH. Brintzinger.. eds., Springer-Verlag 1995); omr in EP 103 120; EP 102 SOm3;

EP 0231 102; EP 0 703 246; REE 33,683; US 4,302,565; US 5 ,518,973; US 5,525,678; UJS 0 5,2=88,933; US 5,290,745; US 5,09 3,415 and US 6,562,905. Exammples of such catalysts incluede tho=se comprising Group 4, 5 or © transition metal oxides, alkoxides and halides, or oxides, alkeoxides and halide compounds of titanium, zirconium cer vanadium; optionally in conmbination with a magnesium compound, internal and/or exterral electron donors (alcoho ls, ethmers, siloxanes, etc.), aluminurm or boron alkyl and alkyl Ialides, and inorganic oxi de .5 supoports. [00m 086] Conventional-ty/pe transition metal catalysts are those traditional Ziegleer-

Natta catalysts that are well known in the art. Examples of conv entional-type transition me-tal cat-alysts are discussed in US Patent Nos. 4,115,639, 4,077,904, 4,482,687, 4,564,605, 4,721,763, 4,879,359 and 4,960,741. The conventional-typoe transition metal catalZyst commpounds that may be used in the present invention include trarsition metal compounds from

Gr -oups 3 to 17, or Groups 4 to 12, or Groups 4 to 6 of the Periodi-c Table of Elements. . [00087] These conventi onal-type transition metal catalysts may be represented by the forrmula: MR,, where M is a metal from Groups 3 to 17, or a mmetal from Groups 4 to 6, osra : me=tal from Group 4, or titanium; R is a halogen or a hydroc=arbyloxy group; and x is the va lence of the metal M. Examples of R include alkoxy, phe=noxy, bromide, chloride and fluoride. Examples of convention al-type transition metal catalyst=s where M is titanium inclwmide

Ti-Cls, TiBrs, Ti(OC;Hs)Cl, TigOC:Hs)Cl, Ti(OC4Hs):Cl, Tia (OCsH;),Ch, Ti(OC;Hs)»Br,

Ti Cl;.1/3AI1Ch and Ti(OC12H25)Chs.

[00088] Conventional-type: transition metal catalysst compounds based on 30 maagnesium/titanium electron-doraor complexes that are useful in embodiments of the invention arse described in, for example, US Patent Nos. 4,302,565 and 4,3(02,566. Catalysts derived frmom

MI g/Ti/CUTHF are also contemp lated, which are well known tc those of ordinary skill in the art. One example of the general method of preparation of such a catalyst includes the fomllowing: dissolve TiCly in THF, reduce the compound to TiCl3 u=sing Mg, add MgCl,, and re=move the solvent.

[00089] Conventional-type «cocatalyst compounds for the above conventional-type tr=ansition metal catalyst compouxads may be represented by the formula MM X*R’., wherein M® is a metal from Group 1to 3 and 12 to 13 of the Periodic= Table of Elements; M* is a metal of Group 1 of the Periodic "Table of Elements; v is a number £rom 0 to 1; each X? is any haalogen; ¢ is a number from 0 to 3 ; each R? is a monovalent hydrocarbon radical or hydrogen; b is a number from 1 to 4; and wherein b minus c is at least 1 Other conventional-type organometallic cocatalyst compourmds for the above conventional-typee transition metal catalysts 0 have the formula M®R%,, where Mis a Group IA, IIA, IIB or IIL A metal, such as lithium, saddium, beryllium, barium, boron, aluminum, zinc, cadmium, and g=allium; k equals 1, 2 or 3 depending upon the valency of M?* which valency in turn normally d=epends upon the particular

Group to which M3 belongs; amd each R® may be any monovaalent radical that include huydrocarbon radicals and hydrocarbon radicals containing a Group 13 to 16 clement like 5 fluoride, aluminum or oxygen or a combination thereof.

Elclymerization [ 00090] Polymerization may be conducted using the above= catalysts and monomers selected from ethylene and one or more a-olefins selected from 1-b-utene, 1-hexene, 4-methyl— )0 Kk -pentene, 1-octene or 1-decene. [£00091] In order to provide a better understanding of the present invention, the following= : examples are offered as related to actual tests performed in the practilice of the invention:

EXAMPLES

35 00092] The polymerizatior reactions described herein were conducted in a continuous ppilot-scale gas phase fluidized be d reactor of 0.57 meters internal diameter and 4.0 meters ir

Wed height. The fluidized bed was made up of polymer granules. The gaseous feed streams o=f «cthylene and hydrogen together “vith liquid comonomer were mixed together in a mixing tees samrangement and introduced below the reactor bed into the recycle gas line. Hexene was usec] sas comonomer. The individual flow rates of ethylene, hydrogen and comonomer were «controlled to maintain fixed composition targets. The ethylene concentration was controlled to _ynaintain a constant ethylene partial pressure. The hydrogen wams controlled to maintain =a constant hydrogen to ethylene mole ratio. The concentrations of all the gases were measured by an on-line gas chrommatograph to ensure relatively corastant composition in the recycle gas stream.

[00093] The solid catalyst was injected directly i-mto the fluidized bed usirmg purified nitrogen as a carrier. Its rate was adjusted to maintain a ceonstant production rate. The reacting bed of growing polymer particles was maintained in a fluidized state by the continuous flow of the make up feed and recycle gas through the reaction zore. A superficial gas veloc ity of 0.6 - 0.9 meters/sec was used to achieve this. The reactor wass operated at a total pressure of 2170 kPa. To maintain a constant reactor temperature, the temperature of the recycle gas was continuously adjusted up or down to accommodate any —hanges in the rate of heat generation 0 due to the polymerization.

[00094] The fluiclized bed was maintained at a constant height (4.0 meters) by withdrawing a portion o f the bed at a rate equal to the ratte of formation of particulate product.

The rate of product formation (the polymer production ra—te) was in the range of 50-"70 kg/hour.

The product was remosved semi-continuously via a se=ries of valves into a fix ed volume 5 chamber, which was simultaneously vented back to the re=actor. This allows for highly efficient removal of the product, while at the same time recycling a large portion of the unre=acted gases back to the reactor. This product was purged to remov=e entrained hydrocarbons and treated with a small steam of hiamidified nitrogen to deactivate amy trace quantities of residumal catalyst.

[00095] Figure L is a schematic of the pilot-sscale fluidized bed reacteor and the approximate locations of the static measuring instruments,

[00096] Readings from the static probes were measured in the form of an electrical . current. The current vas measured by a Keithley Mo del 6517A electrometer {Operating in current mode). Data freom multiple probes were collecte=d simultaneously using a s-canner card in the Model 6517Aa electrometer. Data from each probe were collected at 125 readings/second, and aan average value was reported e=very six seconds. Alterrmatively, the probes were connected to a dedicated Keithley Model 4=85 picoammeter. In this akternate case each static probe was connected continuously to tlhe meter, which reportec] "spot" or instantaneous values of the current every 5 seconds. Daata reported from both typess of current meters was recorded in a computer log, and used to gene=rate the plots shown in Figures 4 — 7.

[00097] Figure 4- shows a dome sheeting incident with a metallocene catalys®, XCAT EZ 100, supplied commercially by Univation Technologi=es, LLC on the pilot-scal-e gas phase reactor. The six traces at the top of the chart show the skin thermocouple resadings (wall temperatures) in the dome. As is well known in the= art, sheeting (and in this case dome sheeting) is indicated by the rapid rise (or spikes) in the skin thermocouple readings. The recycle line static reading showed a steep rise prior to thee dome sheeting incidents, Sfollowed by a sudden decrease. The decrease in measured conveying (recycle) line static is believed to be the result of a recluction in the rate of solids carryover from the reactor. The decreease in solids carryover rate appeared to coincide with the formation of the dome sheet.

[00098] Figure 5 shows four successive dome sheeting incidents with XC_AT EZ 100 metallocene cata lyst on the pilot-scale gas phase reactor. The six traces at the top of the chart show the skin thermocouples in the dome. The corresponding scale is shown wo the right.

Dome sheeting #s indicated by the rapid rise (or spikes) in the skin thermocouple readings. 0 Each of the fowmr incidents produced a dome sheet of sufficient size to block the product discharge port and interfere with fluidization. In each of the four cases the operators were forced to shut doswn the reactor for cleaning.

[00099] T he recycle line carryover static readimmg is indicated by the bottom trace in figure 5. The comesponding scale is shown to the left. Note the steep rise in recyc=le line static \5 prior to each dosme sheeting incident. In the first, third and fourth incidents the recycle line static reached 240 picoamps. In the second incident #he recycle line static peak= reached 95 picoamps.

[00100] Figure 6 shows the same dome sheetimg incidents of Figure 5, wwith readings from the distribautor plate static probes added for comp arison. As can be seen in the chart, the distributor plate static probes showed some response prior to the dome sheeting Sncidents but the response wams not significant, and was not consistert. Since the plate probes amre in contact with the same entrained fines, we would have expected them to show a responsse equivalent (and proportional) to that of the recycle line probe. The reason for the difference iss not known.

[00101] Figure 7 shows a reactor wall sheeting incident with a metallocene catalyst,

XCAT HP 100 catalyst, which is supplied commercial ly by Univation Technologzies, LLC. In this case, a significant response on both of the distributor plate probes was observe=d prior to the sheeting incident.

[00102] ¥igure 7 also provides an excellent illustration of the measurement_ problem that was described gpreviously, that conventional reactor static probes do not provide a meaningful 30 indication prior to a sheeting event with metallocene catalyst. As shown by the resactor trace in the figure, there was no response on the conventional reactor static probe prior mo (or during) the wall sheetirag incident.

[00103] Figure 8 shows the wall sheeting data of Figure 7 with the recyacie line carryover static added for comparison. As can be seen in. the figure, the recycle limne probe did not provide a signifiecant response prior to the wall sheeting incident. The only sig=nificant response from this probe occurred well after the wall sheet was formed. This is an i ndication that all probes present im a reactor system should be monitored, as some may not register static, while others may register static, enabling control through use of continuity additives.

[00104] T he experimental data provides sone important and unexpecte=d results; that the recycle line carryover static probes provide a me aningful response prior to a dome sheeting incident with m etallocene catalyst. The distributer plate probes apparently do not provide a 0 prior indication for dome sheeting.

[00105] Conversely, in the case of wall shmeeting, the distributor plate probes provide meaningful respoonses prior to a wall sheeting Mncident with metallocene catalyst, but the recycle line prosbe apparently does not. Althoug=h these results represent the reverse of the findings with dome sheeting, the present invention clearly provides a solution to the problem of 5 dome and wall sheeting with metallocene catalyst. The carryover static is measured in both locations, the recycle line and distributor plate (cor equivalents), and these mmeasurements are used in combirmation with static control means teo maintain the carryover Static to near-zero levels.

[00106] “Xo determine effective control mesans for maintaining the Carryover static at 0 near-zero levels, various continuity additives wer-e tested as a solution in he=xane or as a solid slurry in mineral oil. The solid slurry was used for the insoluble compe=onents (aluminum . stearate), while a hexane solution was used for the aluminum oleate =and commercially available products sold by Associated Octel Com. pany under the trademark "OCTASTAT 3000 and OCATSTAT 2000. The aluminum oleate =solution concentration wass prepared as 0.40 5 weight percent; the OCTASTAT 2000 and 30G20 solution concentrations were 0.53 weight percent. These solutions were fed into the reaction zone using a positive dllisplacement pump with an effective range of 100-1200 cc/hr. Thee aluminum stearate slurry was prepared by adding the solid aluminum stearate to mineral oil that had been degassed £or 24 hours at 80- 100°F with nitrogen. The resulting slurry concentration was 5.66 weight peercent. The slurry was fed into the reaction zone using a syringe pump with an effective pumpwing range of 1-100 cc/hr. Isopentzane was used as a flush in the feed Mine to the reactor as well.

[00107] Data from pilot-scale polymeriza-tion reactions indicate that separate addition and independemt control of several additives can control and mitigate sheetirag in both the dome and lower sections of a fluidized bed reactor. Many of the continuity additivess are relatively insoluble so they wer—e fed as a slurry in mineral oil, as described above. Soluble materials were dissolved in hexsane and fed directly to the reactor.

[00108] The following compounds were tested ~with the XCAT HP 200 and XCAT EZ

S 100 metallocene catalyst systems:

Aa luminum oleate (solution)

A= luminum stearate (slurry)

OCTASTAT 3000 (solution) (OCTASTAT 2000 (solution) 0 A.5-990 (slurry)

A» TMER 163 (solution)

[00109] Two sseries of tests were performed, one with XCAT HP 2 00 metallocene catalyst and the other on XCAT EZ 100 metallocene c atalyst. The XCAT HP 200 metallocene catalyst test protocol started by running on a dry blend of the catalyst with aluminum distearate (3% based on the we=ight of the catalyst). The additi. ve feed was then started and the reactor was allowed to line out. The catalyst was then switchwed to one where the alun—inum distearate was absent, termed <‘bare catalyst,” assuming there ~were no operability proWblems while the additive was still bei-ng added to the reactor. The fee=d rates of the additive were increased in stages up to around 220 ppm by weight, via a separates continuity additive feed line. The final '0 step was to reduce the additive flow to zero on the bare catalyst. The= XCAT EZ100 metallocene catalyst tests were conducted during attempts to evaluate operability performance of catalysts planned ffor commercial testing. In this ca se, AS-990 was added in response to cold skin thermocouple reeadings (i.e. negative excursions from normal temperatumres) to allow for continuous operatiora on XCAT EZ100 metallocene catalyst. The additivess that produced positive results were= _Aluminum stearate

AS-990 _Aluminum oleate

OCTASTAT 2000

[00110] Sever-al important findings were observed during these triamls. When bare catalyst was used wwithout separate addition of the continuity additive, cold skin temperature readings would deveslop. In some cases these procee=ded to get progressively worse until they suddenly reversed themselves and resulted in a shee ting incident. Higher levels of carryover static were also observeed with the blended catalyst/con®inuity additive. The carry=over static was reduced by addition of higher levels of the continuity additive, generally b y separate addition of continuity additive (separate from the catalmyst blended with continuity additive).

Increased levels of carryover static corresponded to increased levels of reactor static. As the continuity additive flow was increased, the carryover st-atic decreased. Finally, tw=o sheeting incidents were characte=rized by a progressive drop in the carryover static followed by a sudden increase in the carryover static. Running with "bare™' catalyst precipitated these sheeting incidents. At this poimt, skin thermocouple excursions and sheeting occurred. Although the precise mechanism for this is unclear, it appears that the catalyst was attracted to tke walls as 0 evidenced by the drop in carryover static. When the skirm temperature excursion take=s place the catalyst was apparently released and the carryover static ssuddenly increased. [00111}) During testing of the various continuity additives, visual observa tions were made on the dome of the fluidized bed reactor. Whil e running with the catalyst/continuity additive blend, a dome coating was always present. As the additive level was increased, 5 generally through a separate feed line, progressive cle aring of the dome took pl=ace until it completely cleared up to a bare metal wall. For alumminum stearate, this required a total concentration of 10-15 ppm by weight (ppmw), based or production rate. When the aluminum stearate is blended wit=h the catalyst, productivity constraints limit the concentratiorm of stearate to 6 ppm by weight, ams a percentage of the blend (this Fs an approximate level, bul above this '0 level the blend becomes awkward or difficult to h_andle, therefore provides a practical limitation with today =s materials and feed mechanisms). The higher activity ver—sion of the metallocene catalyst recsulted in even lower levels, 3-4 ppmw maximum inclusion i= the blend, demonstrating the nee d for separate addition of the additive.

[00112] Testingz with XCAT EZ 100 metallocemne catalyst was plagued in_ pilot plant 35 polymerization reactions by dome sheeting incidents. However, demonstrations of the invention using the coantinuity additive AS-990 removed the cold skin temperature readings and eliminated sheeting. WFor example, a 10-day run ran smoothly without any operabili_ty problems when a slurry of AS-S90 in mineral oil was fed to the re actor to eliminate cold skin temperature readings near the plate and in the expanded section. ~The AS-990 level in the be=d (from the additional feed) averaged about 10-30 ppm (based on toed weight). An attempt to run without

AS-990, resulted in sk<in temperature excursions.

[00113] Figure 9 shows data from the pilot plant polymerization reactions in the practice of the invention. The: data covers a thirteen day period.

E 00114] The various lirnes at the top of the plot are the skin temperature: s of the reactor. “The lower dashed line showimng step changes is the flow rate of the continuity additives. The low rates were manually rec=orded and varied from 0 to 20 ppm. Point 1 sho=ws the effect on the skin temperatures when the bare catalyst was run, vehich shows the deveBopment of cold skin temperature readings. As the aluminum oleate flow was increased. the cold skin wemperature readings cleared up. Further increases in tlhe flow caused cold sskin temperature meadings to again develop. This demonstrates that there iss an optimum level for= this additive.

H00115] Point 2 showss the result of turning off ®he flow of the alumiinum oleate and munning with bare catalyst. This demonstrates that re duction of the additive has different 0 effects than increasing it - nos cold skin temperature readings but a skin temper—ature excursion. ~This corroborates that that =an optimum level of additive is needed. Overa 1l the runs with aluminum distearate were ve-Ty stable and no cold skin teemperature excursions were observed. _At point 3, the catalyst intro-duced was switched to bares catalyst, which resuMited in cold skin “temperatures again developinmg, but no positive skin temp-erature excursions. 5 [00116] Point 4 show s results with OCTASTAT™ 2000. This additives, similar to the aluminum oleate has an optirmum level. Once the flow o-f continuity additive vewas increased 100 much cold skin temperatures started to develop.

[00117] The plot of Figure 10 corresponds to that in Figure 9, but im this case three different static measurement s are shown. The top line Babeled reactor static WM, is a plot of the reactor static using a curren_t probe, the middle labeleds reactor static 2, lines is a plot of the reactor static using a voltages probe, and the bottom line is a plot of the carryover static. The . carryover static is measuread in absolute value terms. The dashed line is the flow of the continuity additives as descrabed above.

[00118] The carryover static drops during periodss of cold skin temperamture formation at

Points 1, 3 and 4, although teo a lesser extent at point 3. The circled points shomw the addition of blended catalyst containing aluminum distearate. At ak] other times in Figur -e 9, bare catalyst was being fed. This demor=astrates that carryover static is increased when jusst bare catalyst is fed, relative to bare catalyst and with separate addition c=f the continuity additi—ve.

[00119] Figures 11 amnd 12 show plots similar tos those above, but with OCTASTAT®.

In Figures 11 and 12, point 1 corresponds to a concentration of approximately— 5 ppm by weight of OCTASTAT 3000 (total in the reactor), low carry-over static, and cold skin temperature formation occur. However,, as the flow rate of the OC-TASTAT 3000 was ircreased (above 5 ppm), the cold skin temperatures disappeared, whicl demonstrated again the need for an optimum level of the additive (additive amounts awe shown by the dashed line». In Figures 11 and 12, at p-oint 2 the reactor was running vevith bare catalyst and a c-oncentration of approximately 41 ppm of OCATSTAT 3000. Thee OCTASTAT flow was ther stopped. Cold skin temperatures began to develop immediately and at the same time the carryover static began to dec-rease. In contrast to many other continuity additives, this effect occurred immediately a.nd there was no lag in the cold skin temperature development.

[00120] Figures 11 and 12 demonstrate tha=t reactor (conventional static= probe(s)) static was not as readily correlatable with cold skin temperature formation as carryover static measurementss. Although reactor static did show s ome small changes correspording to changes 0 in reactor conditions, the reactor static changess were not as great as the carryover static changes. In addition, this demonstrated how preogressive cold skin temperatures, if left too long, can turrm into a positive skin temperature exc-ursion. Moreover, this demonstrated that the carryover statzic decreased along with the cold skimn temperatures until it reache=d a critical level at which point it began to rapidly increase, followed by a major excurs-ion of the skin .5 temperature, which necessitated a reactor shutdown.

[00121] While the present invention has beeen described and illustratedll by reference to particular embodiments, it will be appreciated toy those of ordinary skill inm the art that the invention lernds itself to variations not necessar-ily illustrated herein. For thhis reason, then, reference should be made solely to the appended claims for purposes of determining the true

J0 scope of the gpresent invention.

Claims (14)

CLAIMS We Claim:

1. A pro-cess for introducing at least one continuity additive into a _ reactor system in an amount that porevents or reverses sheeting of polymer produced by a polymerization reaction of at least one o lefin, wherein the polymerization reaction is conducted in th_e reactor system, the . reactor systerm comprising a fluidized bed reactor, an entrainment zone=, a catalyst feed for introducing a catalyst system capable of producing the polymer, at least ore continuity additive feed for intro-ducing the at least one continuity additive independently of tlhe catalyst mixture, a means for mmonitoring levels of electrostatic activity in the entrainmemnt zone, the process comprising: . (a) contacting the at least one olefin with the catalyst system winder polymerization conditions in the fluidized bed reactor; (b) imetroducing the at least one continuity additive into the reactsor system at anytime before, during, or after start of the polymerization reaction; (c) m-onitoring the levels of electrostatic activity in the entrainment zone; and (d) aedjusting the amount of the at least one continuity additives introduced into the re=actor system to maintain the levels of electrostatic activity irm the entrainment zone amt or near zero.

2. The process of claim 1, wherein the catalyst system comprise s a metallocene or a . conventional transition metal catalyst.

: 3. The gprocess of claim 2, wherein the process comprises a gas phases process.

4. The —process of claim 3, wherein the polymer is produced continucusly.

S. The process of claim 4, wherein the monomers comprise ethylere or ethylene and one or more alpMha-olefins.

6. The process of claim 5, wherein said catalyst system comprises a metallocene catalys system, wh.erein said means for measuring levels of electrostatic activity in the entrainmen

5/068507 PCT/US2004/041988 zone comprise one or more of at least one recycle line static probe, at least one annular disk probe, at least one distributor p late static probe or at least one upper reactor static probe.

7. The process of claim 6s, wherein the at least one continuity additive comprises one or more compounds selected fromn the group consisting of alkoxylated amines, carboxylic acid salts, polysulfones, polymeric polyamines, sulfonic acids, or combinations thereof.

8. The process of claim. 6, wherein the at least one continuity additive comprises ethoxylated stearyl amine.

0

9. The process of claimm 6, wherein the at least one continuity additive comprises aluminum stearate.

10. The process of claim 6, wherein the at least one continuity additive comprises 5 aluminum oleate.

11. The process of claim 6-, wherein the at least one continuity addi tive comprises a mixture of 1 decene-polysulfone preset in a concentration of S to 15 percent by weight of said mixture, a reaction product of N-tamllow-1,3-diaminopropane and epichlorohydrin present in a 30+ concentration of 5 to 15 pezxcent by weight of said mixture, dodecylbenzenesulfonic acid present in a concentration of 5 to 15 percent by weight of the mixture, and a hydrocarbon solvent in a concentration of 60 to 88 percent by weight of the mixture .

12. The process of claimm 6, wherein the at least one continuity additive is introduced 2S intermittently.

13. The process of claim 6, wherein the at least one continuity aciditive is introduced as a slurry in a hydrocarbon liquicll or as a solution in a hydrocarbon liquid. 3¢)

14. The process of claim «6, wherein the at least one continuity additive is also present in the catalyst mixture that is introd_uced into the reactor system via the catal yst feed.

1S.

The process of claim 6,. wherein the amount of the at least one continuity aadditive in the fluidized bed reactor is mainta_ined at a concentration of 1 to 50 parts per million based on the weight of the polymer produce din the fluidized bed reactor.