CA1094749A - Resin rheology control process and catalyst therefor - Google Patents

Abstract

Process for selective production of polyolefin resin of controlled rheology responsive to catalyst morphology in heat activated aluminum treated porous supports e.g., silica gel of regulated moisture content.

Description

~0~47~9 Thls lnventlon relates to the productlon of speciallzed polyole~ln reslns, especlally ~lngle reactor blow moldlng reslns and, more partlcularly, to a catalytlc method ror selectlvely preparlng polyethylene resins Or controlled characterlstlcs e.g., dlstlnct melt rheology.

Molded artlcles, and partlcularly blow molded structures such as bottles are commonly formed from polymers Or l-olerins such as polyethylene. It ls important to the commerclal utllizatlon Or a given polymer system that the con~erted product such as a bo~tle exhlblt an optlmlzed balance o~ propertles, lncludlng ~or example~ acceptable stre~s crack reslstance and rlexural stlrrness. In addltlon, and in a contributlng sense, lt is necessary that the polymer exhlbit sultable processability, i.e., satisractory rheologi-cal behavlor under rlow and derormation durlng fabricatlon.
Although the vlscoela~tlc behavlor o~ polymer melts has been the sub~ect of considerable study, lt has not proven possible to tran~late per~ormance during fa~rlcation to end use artlcles ln such manner as to selectively determlne polymerl-zatlon and partlcularly catalyst requ1rements. Moreover, as ln any case catalyst per~ormance must also be measured ln term~
Or errlciency or productlvlty and sta~ility over a sen~lble llfe.
The uqe Or chromlum compounds in the polymerlzation Or olefin~ 19 well-known. U.S. Pat. Nos. 2~82~,721 and

-2-1 2,951,816 teach the use o~ CrO3 supported on an lnorganlc materlal such a~ slllca~ alumlna or combinations of ~lllca and alumina and actlvated by heatlng at elevated temperatures to polymerize olerins. When these catalyst systems are used ln varlous polymerlzatlon processe~ such as the well-known partlcle-~orm process, the reslns produced, whlle use~ul in many applicatlons, are unsatlsractory for others because of a deflciency in certaln propertles suc~ as melt inde~.
Improved chromium based supported catalysts are 10 known, partlcularly those dlsclosed and claimed in U.S.

3,984,351 and 3,985,676. Such catalysts permit the production of reslns o~ lmproved rlow propertles and shear response, but have been ~ound dl~rlcult to employ on a commerclal scale wlthout product segregatlon or resln blendlng because of 15 varlatlon ln rheologlcal propertles o~ polymer produced, relatlve to its use ln rabrlcatlon and especlally blow molding e.g.
ln accumulator, or accumulator ram equlpment.
An examlnat1on o~ this phenomenOnutlllzlng now classlc measures o~ resln shear response (HLMI/MI values 20 determined accordlng to ASTM-D-1238, Condlt$ons ~/E) evldenced no apparent reason ~or differentlal per~ormance o~ these re~ins in fabrlcation equlpment. Empirlcal studles suggested that a more e~actlng vlscosity analysls wa5 required to lsolate resln candidates adspted to af~ord shortened cycle time~ or 25 otherwi~e 1mproved perrormance ln selected blow molding equipment. It has been ~ound that such a determinatlon may be made u~ing a v~sco~itY ratlo of Etal/Eta1000, broadening the range covered and e~pressly including the range 1 to 1000 1 reciprocal seconds. These values provlde a correlatable measure or critlcal per~ormance in end use as more ~ully descrlbed hereina~ter, and permlt the selectlon Or resin candldates particularly adapted to use in such blow mold-5 lng equipment as the accumulator or accumulstor ram equip-ment a~orement~oned.
Further studles of certain chromium catalysed resln varlabillty in terms of this viscosity ratio charac-teristlc permitted identi~lcatlon o~ production factors crltl-10 cal to the controlled production Or resins of the desiredcharacteristlcs.
Manyik e~ al., ln U.S. Patents 3,231,550 and 3,242,099 descrlbe poly(hydrocarbylalumlnum oxldes) produced by the reac~lon o~ water with an organo hydrocarbylaluminum 15 compound, which are ln turn reacted with transltlon metal e.g., chromlum compounds and used as olefln polymerization catalyst~.
Shlda et al. ln U.S. Patent 3,882,096 dlsclose ethylene catalysts comprising a support lmpregnated with 2U chromlum oxide and the reaction product o~ water and an alkyl ester o~ t~tan~ um~ and heat activated.
Long in U.S. Patent 3,152,105 shows an ~-ole~ln catalyst compr1stng a carboxyllc acid salt of chromium, water and an organoalumlnum compound.
~5 Modiflcatlons in sllica gel for catalytlc activity are shown in Burwell, Chemtech, pp. 370-377 (1974) and Peri, J. Cat. 41, pp. 2~7-23g (1976). None of these prior art disclosures refer to the control of res1n rheologlcal charac-teristics in a process ~or the polymerizatlon of l-ole~lns utllizlng a supported, heat activated chromlum catalyst.

It has been discovered that level and type of alumlnum values deposited upon a supported catalyst critlcally controls its characterlstlcs, and may be employed in a chromlum catalyst system as a direct means to achieve selectlve resin production ln a controlled l-olefln polymerl~atlon The same effects can be achleved indlrectly by establishing and maintaining a fixed ratlo of water to aluminum compound during catalyst preparation.
Briefly, the lnventlon rerlects the discovery that resin property variatlons may be traced to system water, or moisture le~el present in the course of catalyst preparation.
Slllca gel and other lnorganlc catalyst supports are known to be active adsorbents, and readily plck up significant quantitles Or water. (Drled slllca gel with less than 0.5%
water content, slmply poured through 12 lnches of 80F. alr at 50% RH wlll reach a moisture content of 2%). Their exposure to a humid atmosphere l~ accordingly conventionally controlled ln handling, and the le~el of adsorbed water is ordinarily within such low l~mlts i.e., a ~ew percent by weight as not to constitute a noticeable element in the system~
Ho~eYer, such handling procedures as have customarily ~een employed permit considerable variation withln the range.
In the course of preparat~on of re~ins for general use, such moisture variation ln t~e catalyst preparaSion system shows no meanlngful differentlation ln resin perform-ance. However, lt has now been ~ound tha~ heretofore undiscerned difrerences in resln rheologlcal properties can become importan~ to eff~clency in certain critical end uses 1 such as the blow moldlng Or bottles utlllzlng accumulator ram equlpment. Surprislngly, it has been dlscovered that such resin varlations are traceable to and may be controlled by molsture level ln the catalyst preparatlon system.
Whlle not wishing to be bound by an essentlally hypothetical elucldation, it is presently believed that the ~elective performance Or the novel catalyst systems hereo~ may be attributed to the morphology, or stereoconfig-uration o~ the activated catalyst surface relative to the 10 aluminum species ~ormed in situ by controlled hydrolysis.
That is, a series of composltional modifications are believed to result ~rom the hydrolysis reactions with residual moisture in the system, which modi~ications range through vary~ng steric configuratlons of the aluminum-containing moietles, 15 and appear indlvidually to permanently and selectively control polymerization perrormance upon heat activation. Thus, a range of resin properties may be selectively and controllably produced responsive to control of water and aluminum levels employed in catalyst preparation.
In accordance with this invention there is produced a catalyst comprising an inorganic oxide support maintalned under c~ntrolled moisture condition. The alumlnum treated supports may be activated ~y heatlng ~n a non-reducing e.g., oxygen-containing atmosphere at a temperature above about 200F.
25 up to ~he decomposition temperature o~ the support material, and utilizeB directly as a hydrogenation or cracking catalyst e.g., in the isomerization Or hexane, wlth excellent actl~ity, selectivity, sta~ ty and attrition resistance. Thus, such materials may be used as supports wlth other catalytlc promotors 1 ln a varlety of catalysed reactlons or employed directly ror lsomerlzatlon, re~ormlng, cracklng, polymerlzation, alkylatlon, dealkylatlon, hydrogenatlon, dehydrogenation or hydrocracklng reactlons.
Prererably, the support ls coated wlth an alumlnum compound and also treated wlth a catàlytlc element belng a compound o~ a metal selected rrom the group conslsting of chromium, cobalt, nickel, vanadlum, molybdenum and tungsten, or admlxtures thereo~, ordlnarlly as the oxides, and most pre~erably 10 a chromlum containing compound, especially a chromlum oxide, or the organophosphoryl chromlum reactlon product of U.S. Patent 3,985,676 arorementloned.
In the most preferred embodlment Or the present lnvent~on an organophosphoryl chromlum reactlon product is 1~ deposited upon a hlgh sur~ace area sllica gel of controlled water level wlth an aluminum compound reactlve with water, and the catalyst intermedlate so produced is heat activated for use~

~o The lnorganic support materials useful in the present invention include those normally employed in supported chromium catalysts used in ole~in polymerizations such as those dlscu~sed ln U.S. Pat. No. 2,825,721. Typically, these support materials are inorganic oxides of silica, alumina, 25silica-alumina mixtures, thorla, zirconia and comparable oxldes whlch are porous, have a medium surface area, and ha~e surface hydroxyl groups. Prererred support materials are sllica xerogels or xerogels containing silica as the ma~or constitu-ent. ~specially preferred are the silica xerogels desaribed 30in U.S. Pat. Nos. 3,65~,2l4-6 wh~ch si~ica xerogels have a 1 surface area in the range o~ 200 to 500 m2/g. and a pore volume greater than about 2.0 cc/g. a ma~or portion o~ the pore volume being provlded by pores having diameters ln the range o~ 300 to 600 ~.
Such supports are provided with a regulated water content up to 15 to 25 weight percent based upon the support, preferably 0.25 to 6.o weight percent. The support material may be dried or moisturlzed, as by equillbration with the atmosphere, to the selected water level. In general, levels of water much 10 above 3.5% Sy weight will ha~e llttle addltlonal effect upon the results achleved at low aluminum levels e.g., 3.7%, and accord-ingly lower levels are preferred ~or best system control.
Hl~her water levels may be necessary at higher alumlnum levels, e.g. 10%. Optlmum results i.e., increased sensitivity ln resin 15 di~ferentlation are secured when water content is regulated within the limlt 0.25 to 6.0 + 0.15% by weight for the preferred sllica gel.
The aluminum-containing compound employed herein is reacti~e with water i.e., ~ undergoes a controlled hydrolysls 20ranging through stages of partial hydrolysis (depending upon levels of available moisture ln the system re~ati~e to alum~num compound charged) correlata~le wlth selecti~e aluminum specles, and admixtureg thereo r . The aluminum compounds are also reactiYe with th~ sur~ace hydroxyl groups o~ the lnorganic 25support material, as are the reaction products w~th water.
Preferred aluminum compounds may be presented by the formula:
Al(X)a(Y)b(Z)c wherein X ls R, Y is OR, and Z is H or a halogen; a ~s 0-3, -a-10~4749 1 b ls 0-3, c ls 0-33 and a + b ~ c equals 3; and R 18 an alkyl or aryl group having from one to eight carbon atoms.
Esamples Or such aluminum compounds include alumlnum alkoxides ~uch as alumlnum sec-butoxlde, alumlnum ethoxlde J
alumlnum i~opropoxlde; alkyl alumlnum alkoxldes such as ethyl alumlnum ethoxlde, methyl alumlnum propoxide, dlethyl alumlnum ethoxlde, dllso~utyl aluminum ethoxide, etc.; al~yl alumlnum compounds such as trlethyl aluminum; trllsobutyl alumlnum, etc.; slkyl or aryl alumlnum halldes such as dlethyl alumlnum tO chlorlde; aryl alumlnum compounds ~uch as trlphenyl alumlnum, aryloxy alumlnum compounds such as alumlnum phenoxlde and mlsed aryl, alkyl and aryloxy, alkyl alumlnum compounds.
For the preparatlon of the preferred polymerlzatlon catalysts, the support 18 treated wlth a chromlum-contalnlng 15 compound, be~ore heat actlvatlon.
The chromlum contalnlng compound~ useful ln the present lnventlon comprlse any chromlum containlng compound capable Or reactlng wlth the surrace hydroxyl groups Or an lnorganlc support. ~xamples of such compounds lnclude chromium 20 trio~lde, chromate esters such as the hlndered dl-tertlary polyallcycllc chromate esters, 8ilyl chroma~e esters and phosphorus contalnlng chromate e~ters disclosed ln U.S. Pat.
No~. 3,642,749; and 3,704,287, and organopho~phoryl chromlum compounds such as those dlsclosed ln U.S. Patent No. 3,985,676 whlch comprlse the reaction product of chromlum trlo~lde wlth an organophosphorus compound havlng the ~ormula:

Il l R0 - P - OR Or RO - P - OR

_9_ ~0~4749 wherein R i~ alkyl, aralkyl, aryl, cycloalkyl or hydrogen, but at least one R i8 other than hydrogen. The preferred organophosphorus compounds are trialkyl pho~phates such as triethyl phosphate.
The novel catalyst of the pre~ent invention may be prepared by depositing the chromium containing compound and the aluminum compound on the inorganic support in any suitable manner such as by vapor coating or by impregnating the ~upport with solutions of the chromium containing compound and the 10 aluminum compound in a suitable inert ~olvent which i~ normally an anhydrous organic solvent. Such organic solvents include aliphatic, cycloalkyl, and alkylaryl hydrocarbon~ and their halogenated derivatives. A preferred organic solvent i~
dichloromethane, The chromium and aluminum compoundQ may be 15 applied to~ether or individually.
In applicant's usual method of catalyfit preparation, the support i3 impregnated first with the chromium containin~
compound and then the aluminum compound. Most preferred for optimum reproduci~ility i8 anhydrous organic solve~t ~pplica-20 tion by impregna~ion, employing a~out 1 to 2 pore volume~ ofsolvent such a~ methylene chloride.
When an organophosphoryl chromium compound of the type disclosed in the aforesaid U.S. Patent No. 3,g85,676 i8 utilized in the practice of the present invention, it i8 26 preferred to employ t~e particular catalyst preparation techni~ues described in that application, In such in~tance the organoaluminum compound may be applied to t~e catalyst upport under conditions similar to those utilized for 109~749 1 deposltlon Or the organophosphoryl chromium compound.
The most erfective catalysts have been round to be those contalnlng the chromlum compound in an amount such that the amount o~ Cr by welght based on the welght of the support 5 is rrom about 0.25 to 2.5% and preferably is ~rom about 0.5 to 1.25%, although amounts out~lde o~ these ranges stlll yield operable catalysts. The alum~num compound should be added in suf~lclent amounts to provlde ~rom about 0.1 to 10% Or aluminum by weight based on the welght of the support and pre~erably 10 rrom about 0.5 to 5.5% although other amounts outside of these ranges can be used to prepare operable catalysts.
After the chromlum contalning compound and the alumlnum compound have been deposlted on the inorganlc support, the support ls heated ln a non-reducing atmosphere, pre~erably 15 in an oxygen containlng atmosphere, at a temperature above about 200F up to the decompositlon temperature of the support.
Typically, the supported compositions are heated at a tempera-ture o~ from 800F to 2000~. The heatlng time may vary, for example, depending on the temperatures used, from 1/2 hour or 20 less to 50 hours or more. Normally, the heatlng ls carried out over a perlod o~ 2 to 12 hours. The non-reduclng atmosphere which is preferably alr or other oxygen containlng gas should be dry an~ preferably should ~e dehumidified down to a rew parts per milllon (ppm) of water to obtain maxlmum catalyst 2~ actiYlty. Typically, air used in the procedure described in thls app~lcation i~ drled to less than 2-3 ppm o~ water.
Although anhydrous solvents in the deposition procedure, and dehumidifled air in drying or heat activation are normally employed, in prac~lce control o~ moisture on the 1 support is found sufficient to achieve the objects of the invention. It is of course also possible at constant support water level to adjust by moisture present in the solvent treatment systems. Time of reaction or interaction of the 5 aluminum compound does not appear to be critical, and deposition is normally effected under ambient conditions, as in a conventional blender-coater apparatus.
Also, the catalyst may be prepared by separately activating the catalyst after the addition of each separate 10 Component.
The absolute level of aluminum compound and the ratio of water to aluminum compound is considered important to the controlled polymerization of the present invention. In general, the proportion of aluminum compound may range from about 0.1 to 10% by weight, based on the support, preferably from 0.35 to 5.5~ and will, at constant moisture level in the preparation, evidence in use decreasing molecular weight with alumin~m level and increasing molecular weight distribution as measured by melt index values on resin produced. ~he water to 20 aluminum molar ratio may vary from an esse~tially anhydrous system to about 4.0, preferably 0.5 to 2.0, with lower values correlating w~th lower molecular weight and intermediate shear response, or molecular weight distribution.
Proportions of water and aluminum compound have heen 2~ expressed herein in terms of weight percent based upon the aluminum-containing support, and molar ratio of water on alum~num-containing support to aluminum. While these values may be readily calculated, for ease of conversion, reference may be had to the following ta~le.

~ ~ .. '''1 1~ - ~ .1~
~ ~ r ~ ~ ~

1 Control o~ these respectlve variables under other-wlse equivalent operating conditions accordlngly Or~ers res-ponslve selectlon Or resln characterlstlcs. However, as noted herelnabove, the di~rerentiatlon of resin characteristics, 5 although crltlcal to rabrlcators, may be a3certainable only throug~ t~e use o~ speclallzed melt vlscometry measurements.
Certain fabrlcation equlpment such as accumulator ram blow moldlng equlpment 18 responslve to melt rheology correlatable P
wlth hlgher shesr rates and dl~erent shear rate respon~e than 10 may be determined utlllzlng conventlonal melt lndex measurement~.
Accordin~ly, ~or the purposes o~ this lnventlon melt viscoslty ls measured dlrectly as 'Eta', at shear rates o~ 1 and lO00 reclprocal seconds, and shear response is expressed as the vl~cosity ratlo Etal/~tal0OO. This measurement provldes a 15 rellable tool for correlatlng reproduclbly resln r~eology wlth rabrlcatlon requlrements. Lower water to alumlnum ratlos eYldence lower ~ta values (lower molecular welght) and lntermedlate vlscoslty ratlos (broadest shear response, or molecular welght distributlon ls evident at an lntermedlate water to alumlnum 20 ratio); and lower absolute alumlnum level~ evldence lncreased Eta value~, and lower viscoslty ratlos at constant water ~o aluminum ratlos.
Specl~lc reslns may accordingly be tailored ror use, e.g.,ln respect o~ shear level and re~ponse by control Or water 2~ to aluminum ratloa and alumlnum coatlng levels.
~ est results have been achleved with organophosphoryl chromlum reactlon product on Polypor 8illC8 gel for accumulator ram blow moldlng equlpment at an abaolute aluminum level o~ .5%
and a water to alumlnum molar ratlo of .5, the reslns ~o produced triethyl boron 3Q under standard condltions ~l ppm ~ about l wgt.% Cr and H2 .3-.7 mol%) evidenclng a vlscoslty ratlo o~ about 37 to 43.
* Trade Mark 1 Obv1ously, the shape of the molecular weight distribution curve and therefore shear response ~t a given average molecular welght may be controlled by the artisan in accord-ance wlth the invention.
The heat-treated supported chrom~um and aluminum compounds of the present invention may be used in combination wlth metalllc and/or non-metalllc reduclng agents to pro~lde no~el catalyst systems ror the polymerlzatlon of ole~lns.
Examples of metallic reduclng agents include trialkyl alumlnums, tO such as trlethyl alumlnum, triisobutyl alumlnum, alkyl aluminum halldes, alkyl aluminum alkoxides, dialkyl zinc, dialkyl magnesium, and metal borohydrides including those of the alkall metals, especially sodium, l~thlum and potassium, and Or magnesium, beryIium and aluminum. The non-metal 15 reducing agents lnclude alkyl boranes such as trlethyl borane, trllsobutyl borane, and trlmethyl borane and hydrides or boron such as d~borane, pentaborane, hexaborane and decaborane.
For e~ample, based upon a cataly~t composltion containing about 1% by weight of Cr based upon the weight Or 20 the support, the preferred amount of an organometalllc reducing agent ~or use therewlth, e.g., trll~obutyl alumln~n ~TIBA~ s about ll.4% by welght and equlvalent to an Al/Cr atomic ratio o~ about 3/l. The prererred range o~ atomic rat-los of Al to Cr is from about 0.5/l to about 8/l, or rrOm 25 about l.g% to about 30% by weight TIBAB. The o~erall practlcable l~mlts of TIBAL ln terms of the Al/Cr atom1c ratlo are from about Q.l/l to 20/l, and ln terms o~ we~ht are ~rom about 0.4~ to abo-~t 75% by we1ght~

1 The heat-treated, supported chromlum containing compound and alumlnum compound may be combined with the metallic or non-metallic reducing agent prior to being red to an olerln polymerizatlon reactor or these two components may 5 be ~ed separately to an olerln polymerlzation reactor.
In proportioning the amount of metalllc or non-metalllc reducing agent to the amount of chromium compound used ln the catalyst systems o~ the present lnvention, ~airly wide latitude is available, but some guidellnes have been 10 establlshed consl~tent wlth good yield, ~a~orable polymer properties and economic use or materlals. For example, in the u~e o~ metallic and/or non-metallic reducing agents with an amount of chromium compound sufriclent to yield about 1% Cr by weight of the support the parameters set forth below are 15 representatlve. The atomlc ratlos are based upon a calculatlon of the metal in the metalllc reduclng agent and/or the non-metal in the non-metalllc reduclng agent versus the chromium content present in the chromlum compound on the support.
Another example of an organometalllc reducing agent 20 for use ln con~unction with the catalyst compositlon of the pre-sent inventlon ls triethyl alumlnum. Agaln based upon a cata-lyst composltion contalnlng about 1% by welght of Cr based upon the welght of the support, the pre~erred amount of trlethyl aluminum ~TEA) is about 6.6% by weight based upon the weight 25 of the support giving an Al/Cr atomic ratio Or about 3/l.
The pre~erred range of atomic ratios of Al to Cr ls ~rom about 0.5/1 to about 8/1, or from about 1.1% to about 18% by weight of TEA. The overall practlcable limits of T~A, in terms of an Al/Cr ratlo, are from about 0.1/l to 2~/l, and in terms of weight 30 are rrom about 0.22% to about 44% by weig~t.

~094q49 1 Trlethyl boron (TEB) may be taken as the prererred e~ample Or the proporations Or non-metalllc reduclng agent ror use ln con~unctlon wlth the catalyst composltlon Or the present lnventlon. Agaln ba~ed upon a catalyst compositlon contalnlng 5 about 1% by welght Or Cr based upon the welght Or the support, the pre~erred amount Or TEB ls about 5S by we~ght based upon the welght o~ the support glvlng a B/Cr atomlc ratlo Or about 2.7/1. ~he preferred range Or atomlc ratlos Or B to Cr ls from about 0.1~1 to 10/1~ or rrom about 0.19 to about l9S TEB. The 10 overall practlcable llmits, ln terms of a B/Cr ratlo, are from about 0.01/1 to about 20/1, and ln terms o~ welght, are ~rom about 0.02S to about 38% by welght based upon the welght Or the support.
As lndicated above, the pre~erred catalyst composltlons 15of thls lnventlon are employed ln conventlonal polymerizatlon processes ror oleflns, ln partlcular l-olerlnQ havlng 2-8 carbon atoms such as ethylene, propylene, l-butene, 3-methylbutene-1,

4-methyl pentene-l alone or ln admlxture, and copolymerlzatlon thereor wlth ethylenlcally unsaturated monomers such as vlnyl 20aceta~e, acrylonitrile, or methyl methacrylate wlth or w~thout modirlers, chaln tran~rer or terminatlon agents and the like, as ~nown ln the art. Such polymerlzations may be effected under temperature and pressure condltlons generally employed in the art e.g., temperatures of from about 40 to about 200C and prerer-2~ably r~om about 70 to 110C, and pressures o~ ~rom 200 to 1000p51g and preferably rrom 300 to 800 pslg, as are used in slurry or partlcle ~orm polymerizatlonq.
The catalyst o~ the lnvention appears to act uniquely ln the po~ymerlzation Or l-ole~ins, especially where hydrogen ls 30employed in the polymer~zation zone, in that the relatlon of 10~474g 1 molecular welght and molecular welght dlstrlbutlon responslve to hydrogen demand 18 modirled, a~ compared to catalysts ln whlch water level ~s not controlled. Thus, the excellent hydrogen response evldent at low water to alumlnum mol ratlos

5 permlts wlder latltude ln hydrogen leYels whlle malntalning acceptable productlvlty. In addltlon the shape Or molecular welght di~trlbutlon curves can be distinguished, wlth impllca-tlons to shear reaponse and dle swell properties.
These capabllltles translate into resln performance.
10Heretofore, it had been common practice and a commercial necesslty to provide the necessary rheological properties for employment ln certaln extrusion and rorming operatlons, notably blow moldlng, by blendlng together re~ln product~ o~ more than one reactor, as a comblnatlon o~ solutlon and partlcle form 15resins. In accordance wlth the present 1nventlon a single resln l.e., the product o~ a 'slngle reactor' serYes to provide the necessary rheologlcal properties directly.
The rollowlng examples lllustrate pre~erred modes Or carrying out the preparatlon of the novel catalyst hereof, and 200f the use o~ such catalyst ror the preparation of polyethylene~
o~ modlrled and controlled rheologlcal properties. It wlll be understood that the e~amples are illustrative only and that Yarlous modiflcations may be made ln the ~peclfied parameter~
wlthout departing ~rom the scope o~ the tnvention.
The melt vlsco~ltie~ reported are determlned wlth an lnstron Capillary Rheometer at 190C and a~ shear rates o~ 1 to 1000 reciprocal second~. The Vl~cosity Ratio e~pressed 1~ the ratlo of ~tal/~talooo~ referring to the 1 and 1000 reclprocal second values, respectively. Absolute Yalues are reported as 30poise.

~094749 1 Melt indlces where recorded, are determined ln accord-ance w~th ASTM-D-1238, Condltlons E(MI) and F(HLMI),HLMI/MI
ratlo~ are measured only over a lOX shear rate range.
Water determinatlons were made ln ~tandard manner 5 employlng a tltratlon technlque ln pyrldlne uslng Karl Fi~her reagent, and are calculated by welght ba~ed upon the aluminum-contalning support.
The 'slngle reactor' re~in o~ the lnventlon exhlblts a melt lndex o~ up to about .4, a vlscoslty ratlo of 35 to 45 10 and melt strength, dle swell, and parl~on extruslon tlme equlvalent to otherwise comparable resln blends, rendering it partlcularly well adapted ~or use ln ~orm~ng operations including employment as the ~ole resin in blow molding utilizing accumu-lator or accumulator ram equlpment, known for lts crltical 15 acceptance o~ re~ln candldates wit~ particular regard ~or cycle - tlme, and wall dlstributlon, trimming characterlstlcs, top load values and surface propertles Or ~abrlcated artlcles.
For blow moldlng, resln may be prepared havlng a denslty Or 0.953 to .955, a melt lndex of 0.25 to 0.40, a melt 20visco~1ty Or 3.65 to 3.85 x103 polse at lO00 sec~l, a vlscoslty ra~io of 35 to 45, and a die swell at lO00 sec Or 170-185%.
The rollowlng method~ may be used to prepare the ca~ya~s used ln ~he ln~entlon rererr~ngl for purposes Or exe~pli~icatlon oniy, to certaln pre~erred em~odiments:
26 The lnorganlc oxlde support, represented by slllca xerogel havlng a pore ~olume Or about 2.5 cc/g prepared ln accordance wlth the dlsclosure in U.S. Patent No. 3,652,215 t~
regu7ated to a ~elected molsture leYel as descrlbed hereinabove, usually at leas~ 0 25 and 6.o percent by weight + 0.15% b~
30~rylng ln nltrogen at an elevated temperature under vacuum or 1 mol~turlzlng ln contact wlth a humid atmosphere, and thereafter coated wlth the alumlnum and chromlum compounds, or other catalytic material.
In the case Or spray coatlng, the alumlnum compound 5 represented here by aluminum sec-butoxlde, 1~ diluted wlth one pore volume (relatlve to slllca gel) methylene chlorlde and sprayed onto the neat or chromlum coated support at 90F over a perlod of one hour (durlng whlch 3 bed turnovers are accomplished~
The coated catalyst ls drled at 235F. for two to slx hours at 10 10-15 in. Hg, vacuum to remove volatlles. In a preferred modlflca-tion Or thl~ procedure, the alumlnum compound is slurrled with two pore volumes Or anhydrous methylene chlorlde, and the solvent removed by drylng as afore~ald.
Vapor coatlng may be achleved in slmilar manner by 16spraylng the support, maintalned at a temperature of 400F, with the aluminum compound at 175F over a perlod of 1.5 hours, then raislng the temperature rOr drylng, to 500F malntalned for 1 hour at maxlmum vacuum.
The gel at regulated molsture level may also be simply 20slurr~ed in a su~table anhydrous solvent such as methylene chlorlde wlth the alumlnum compound and the chromlum compound, and there-arter drled to remove volatlles. The drled cataly~t may be blended wlth un$rea~ed siltca gel, sllica gel coated wlth chromlum compound or other support material where ~urther ad~ust-25ment ln water to alumlnum ratlo ls deslred, e~peclally tocal~ulated le~el~ of water ba~ed upon the aluminum-contalning support o~ belo~ 0.4 welght percent.
To heat ac~1vate the catalyst, the supported catalyst ~5 flu~dized with dry alr at 0.20 feet per minute linesl velocity while being heated to a temperature of 900C. and held at this temperature for 6 hours. The activated supported catalyst is recovered as a powder.

EXAMPLE I
Silica gel having a pore volume of about 2.5 cc/g prepared in accordance with the disclosure in U.S. Patent No.
3,652,215 is added to a 2000 ml, three-neck round ~ottom flask equipped with a stirrer, nitrogen inlet and y-tube with water condenser. A nitrogen atmospher is maintained during the coat-ing operation. Dichloromethane is then added to the flask containing the silica gel and stirring is commenced to insure uniform wetting of the gel. A dichloromethane solution of the reaction product of CrO3 and triethyl phosphate prepared as described in U.S. Patent 3,985,676, is then added to the flask in sufficient quantity to provide a dry coated cataiyst contain-ing about 1% by weight of Cr. The supernatant liquid is removed by filtration and ~he coated gel is dried in a rotary evaporator at 60 C. and with 29 inches of Hg vacuum.
Dichloromethane is added to a similar flas~ as pre-pared above and while maintaining a nitrogen atmosphere stirring is commenced. To the flask is added the supported chromium composition as prepared a~o~e. A solution of dichloromethane and aluminum sec-butoxide is prepared in a pressure equalizing dropping funnel and the funnel attached to the stirred flas~.
The aluminum sec-butoxide solution is gradually added to the flas~ at the rate o~ 10 grams of solution per minute. After the addition of the solution is complete the slu~ry in the flas~ is stirred for about 1 hour. The supernatant liquid is removed by filtration and the 1 coated gel ls dried in a rotary evaporator at temperatures up to about 60C and 29 inches Hg vacuum.
The supported catalyst is placed ln a cylindrlcal container and fluldlzed wlth dry alr at 0.20 ~eet per second 5 lineal veloc~ty whlle belng heated to a temperature of 900C
and held at thls temperature ~or 6 hours. The activated qupported catalyst i8 recovered a~ a powder.
A series o~ polymerlzations are carried out to illustrate the results from using a varying amount of the aluml-10 num compound in the preparation of the catalyst level of 1% Cr,at cons~ant water level in the support wlth results set ~orth ln Table II.
Except as noted, polymerizations are carrled out at 93.5C and hydroge~ (30 psi) and triethyl borane ~2.7 B/Cr 15 atomic ratlo) is added to the polymerization reactor.
TABLE II

P d ti i ro uc ~ ty Al~ wt./SiO2(1) (gms Polymer/gm cat./hr. Ml~LMI

None ~58 low 7.0 .1 1328 0.04 9.1 .2 717 0.05 11.4 1.~ 780 o.36 67.5 2.4 g26 1,10 116.5 253'7 ~86 2.68 340 5.5(2) 616 4.90 390 (1) gms Al per 100 gms SiO2 support ~2) Polymerization temperature 99C B/Cr atomlc rat~o 2.9 ~094749 Supported chromlum-containlng catalyst (l weight % Cr) prepared as descrlbed ln Example I and comprlsing l.85% Al as aluminum sec-butoxlde (solvent coated with 2 pore volumes of 5 methylene chloride) on silica gel at varlant water levels as indlca~ed is utilized ln an ethylene polymerlzation at l ppm TEB, at varying hydrogen level to secure target MI resin, with the results set forth in Table III:

..
,, U~
0 ~ ~D ~ C~l t~
,, ,, a~ o o o a~ o 6q ~ J~

U~
r; ~ ~n U~
O o ~n Q~ o o o o ~, N
I

O
O
o ~ ~
3 ~1 ~ri ~
b~ ~ Ln ~ O r~7 O ~U~
H c) ^
H ~0 0 ~ ~1 ~
~3 ~

E~ H
~ ~ ~1 ~U

:E: c~ ~ J
C~
O ~ ~ ~1 t~~J ~ ~1 (`.1 5~:.

h ou~ ô
ed 3 d o o ~/
~ ~U~
3 ~ o o ~ ~

A further polymerlzation o~ ethylene i5 conducted at a temperature o~ 220F, a hydrogen level Or 0.5-0.8 mol%
(ethylene = 6-8 mol%) to secure target M.l. Or .30 + 0.5, 5 and 1 ppm trlethylborane utllizing a heat-act~vated cataly~t composed of organophosphoryl chromium reaction product (1% Cr) on Polypor sllica xerogel (manufactured by National Petro Chemicals Corp.) at 0.5 to 0.6 water level, coated (2 pore volumes, methylene chloride) with 1.85 weight percent alumlnum as 10 alumlnum sec-butoxlde, blended at about a 4:1 weight ratlo wlth the same chromlum-contalning catalyst wi~hout added aluminum compound (nomlnal water level o.5-0.6 welght percent) to provide a water (calcu}ated on aluminum-contalning support) to aluminum molar ratio of 0.5 and an aluminum level (calculated on total 15support)of 0.5 welght percent.
The resin produced is Or about .953 den ity~0.3 melt index, a melt viscoslty of 3.75x103 poise at 1000 sec~l and a vlscoslty rat~o of about 40. The resin exhlbits a die swell o~ 171% at 1000 sec~l and may be run successfully without blending 20On an accumulator ram blow molding device to produce e.g., a 22 oz.
detergent bottle wlth equlvalent parison e~truslon and cycle times as compared to blended resins.
XAMPLE IV
A catalyst ls prepared ~rom the reaction product o~
25CrO3 and triethyl phosphate (prepared as set ~orth in U.S. Patent 3,98~,676) deposited at about 1% by weight Cr on slllca xerogel havlng a surface area of about 300m2/g. and a pore volume of about 2.5 cc/g, contalning 7.4% water, coated with 10% by we1ght alumlnum as aluminwm sec-butoxide (coatings wlth 2 pore volume 1 o~ methylene chloride), dried and heat actlvated.
Ethylene ls polymerlzed with said catalyst and trlethyl boron at 210C, 30 psi H2, and 3.7 B/Cr ratio to produce a polymer o~ M.I. 8.2.

2~

Claims (7)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A single reactor blow molding polyethylene resin having a density of .953 to .955, a melt index of 0.25 to 0.40, a melt viscosity of 3.65 to 3.85 x 103 poise at 1000 sec-1, a viscosity ratio of 35 to 45, and a die swell at 1000 sec-1 of 170-185%.

2. The single reactor blow molding resin of claim 1 produced from the catalytic polymerization of ethylene in the presence of a chromium-containing catalyst comprising an aluminum compound reactive with water on a porous inorganic oxide support wherein the aluminum content comprises from 0.1 to 0.5 weight percent based upon the support, the water content of said support comprises 0.5 to 0.8 mols of water per mol of aluminum, said catalyst having been activated in a non-reducing atmosphere at a temperature of from 200°F up to the decomposition tempera-ture of the support.

3. The blow molding resin of claim 2, wherein said chromium catalyst is an organophosphoryl chromium reaction product, and the support is a silica xerogel having a surface area of 200 to 500 m2/g a pore volume greater than about 2.0 cc/g, a major portion of said pore volume being provided by pores having diameters in the range of 300 to 600 A.

4. In a process of preparing blow molded containers in accumulator ram blow molding equipment under conventional conditions from polyethylene resin, the improvement which comprises employing as the sole resin charged the single reactor blow molding resin of claim 1.

5. A bottle blow molded from the resin of claim 1.

6. A process for the production of polyolefin resins comprising polymerizing at least one 1-olefin at eleva-ted temperature and pressure in a polymerization zone compris-ing a catalytic amount of a polymerization catalyst for said 1-olefin, said catalyst comprising porous inorganic oxide sup-port coated with an organophosphoryl chromium reaction product and an aluminum compound component and heat activated said alum-inum compound component being hydrolyzed by reaction with a con-trolled amount of water.

7. A process for the production of a polyolefin resin of selected rheology comprising polymerizing at least one 1-olefin in the presence of a supported chromium containing catalyst, said catalyst comprising a silica xerogel having a sur-face area in the range of 200 to 500 m2/g and a pore volume greater than about 2.0 cc/g a major portion of the pore volume being provided by pores having diameters in the range of 300 to 600 .ANG., having coated thereon an aluminum compound reactive with water, the water content being regulated within the limit 0.25 to 6.0 ? 0.15 weight percent, and heat activated in a non-reducing atmosphere at a temperature of from 200°F. up to the decomposition temperature of the support.