DE1904878A1 - Process for the continuous polymerization of ethylene - Google Patents

Description

The invention relates to a process for the polymerization of ethylene at high pressures.

When polymerizing ethylene at high pressures with Free Raditcale-producing initiators are known to be a product which improved in several respects Has properties, can be produced if the polymerization is carried out in two or more zones in a continuous reactor »In such processes, the Polymerization in the first zone with a sufficient

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low. Temperature carried out to make a polyethylene that has a greater molecular linear! than it is typical for high pressure polyethylene., then before that. Beakt'lon mixture was introduced into a second course or in Kweifce gonen and was subjected to a further polymerization in the presence of a further initiator or by further initiators and at a higher temperature or at a higher temperature in each zone initiators used this kind _s were that they showed a maximum efficiency in the Teaipsratupbereieh, in which the operation jeweiligst in! 2one was carried out. In this way, polyethylenes were prepared _s untl the lower to some extent the desired characteristic properties of polyethylenes Dioiite he had ~ desired characteristics of higher density polyethylenes together ,. For example, a balance can be achieved between the viscosity properties of low-density polyethylene and the good rheological properties of higher-density polyethylene "

It is already known 1f-allyl transition metal compounds as initiators for the polymerization and oligomerization of ethylenically unsaturated monomers including To use ethylene »The known conditions for these processes were in general conditions that were known low-pressure processes for the polymerization of. Olefins are typical, however, in the German patent application

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OS?, O v-uFGö-sin process Eur Fo? ./ asri.satioL · from .BQh ungfesät-tlgfc-en monomers . Connections., Insfoe thus ere ethylene * - before-geeelilsgen. in which the monome ': - or · the Moi ^ oiBeren with a «ro ir-aHyll see initiator- at DrfJUilcen above 3.00 at., preferably above 1000 at ^, is or are contacted,

It has now been found that the llyl transition metaX! Compounds with peat! 1 as initiators. For the first zone in a high-temperature solution for the polymerization of ethylene with saddles or more polymerization Beschri efosn 'jsurde ^ used warder ·, germinate- <, - -' ----- ""

Thus, according to the invention, a method for controlled polymerization of febylene in two or more zones is one. . continuous reac £ & rs suggested which dacurcb, characterized isfca öaS one the ethylene durch.eine first PoIygi - ^ - r isat ionssone mife a pressure of -not less than ΙβΟΟ at uaö. .with a temperature not working. · little as ³ 1'23 ° C hrluiurehfUhrt, sine 'B'.? - Allyltibergaogsmatallverbindung in said zone to iZwn r-kung DER Initlierung polymerization-introducing the _Λ, R- Hkki gas mixture of polymer and unreacted ethylene s ., with or ohxie additional ethylene, dursh a second polymer - siitions2: one with INEM and pressure of at least lÖOQ at a higher temperature and in the presence -one "free radicals produce" · -3en Polymerisationslnltifitors passes ,,, the combined. conditions: the temperature and the pressure of Io, each zone are such that the Monofflsr * / polymer Reaktionsgeißisc *.

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the only flowing phase exists and aas Realr & Ions- ■ mixture remains as the only flowable phase until it is out. the named zone exits "" ■ -: ■ - ". ■ -

It is true that the addition of an inert liquid is used as an inert liquid and as a susceptibility medium can be carried out according to requirements, which serve as carriers for the introduction of the IaIMators or any other poly used in the process ^.: merisatiönsmodlfizieraiiOtel in the reaction. »- ·

The determination of whether the monomer / polymer reaction unit is present as the only flowable phase can easily be established by a person skilled in the art or determined from the data in "Fluid Phase Equilibria" in .the system Polyethylene = Ethylene ", I und.II, Re.e. TräVi 'Chi "! -. "84_, 261 (1965) (from Svjelheim, de Swaan Arons- ■ -und Diöpen) mid" 8 ^ ₄ . 504-516 (1966} (from. Koningsveld. '.. "Die-pen and Gher-min) are given. The minimum pressure and the minimum temperature at which the reaction takes place in a" single "" flowable phase "are of one another For example, at a: temperature of 125 ° C, a pressure of>half-fl; 600 at is required.

while at a pressure: from 1600 et ^ ine ^ ^ mperatur above icfr'fst ^ «nT-efoe ^ inphasehre ©. - ■■■ ..- ■■■■■ upright--. Phase balance is also ^{balanced 1} by the ^; - ^:

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BATH ORIGINAL

190-878

Conversion of monomer to polymer, affected by the molecular weight of the product and, to a lesser extent, the degree of linearity of the product

It has been found that the use of pressures and temperatures below those at which the monomer / polymer '■ reaction mixtures are present in a single flowable phase. » results in an undesirable non-uniformity of the product and that the maintenance of a single flowable phase greatly reduced the risk of explosive decomposition occurring and can also cause a non-uniform reaction _Λ which leads to explosive decomposition

The polymerization in the first zone - preferably carried out at a temperature between approximately 1 ^ 5 and 220 or 260 ° 0, temperatures in the order of magnitude of βΟ to 180 ° C. are generally preferred, since they are sufficiently high that an economical reaction rate results _s and since they are low enough that the desired. Balance of the polymerization In the two idea, zones get x ^ irdo It is preferred to work at these temperatures under a pressure of at least 17ΟΟ at au «to ensure * that the reaction proceeds in a single flowable phase. The operating temperature in the second zone and in optionally

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present-further zones is preferably higher- than in

the first zone, but exceeds the preferred temperature in general. ; 3OO ° C not-

The expression "1T = allyiülJergangsmetallvepbliiung" is an organotallized compound of a metal of groups IVA "to VIII, preferably IVA to VIA ₁ , of the periodic table, the at least one ally3.che group of the general formula

■ ■■ '■■■■: - ■ -, -. ^R 5 ■ "^::;;;". ■

■■■. »■ - 1

R ₁ R ₂ C -C- CR ₁₁ = B ₅ having the s bound to the metal Isto

In the formula I R set to R ₁ - * - may be the or different, which are the same, are hydrogen atoms or monovalent Substi-tuenten represents ₅ as s "B * hydrocarbon groups such as alkyl, aryl, Aralkylj, Älkaryl or alkenyl (wherein also cycloalkyl enclosed is), or a substituted derivative thereof or -N0 ₂ 3 »CN or => QR ~ groups, in which R is a hydrocarbon ^ -" group. Alternatively, two or more of the free valences saturated by B. to R, - can be replaced by a divalent organic radicals linked to one another, such as a polymethylene or alkylidene group,

The Periodic Table to which this is taken Besug _s is the iangperiodische Table of the Elements, the domestic on · the - back "wärtigen envelope in" General and Inorganic Chemistry "by

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Part-iiigi -.- & ■ ... r.vbr-i-Uisg-3ge-Ksn by M & cniiXi & iiu "edition ,, ange

give 'is

Suitable Metslxe sinei ScB.- Titan ,. Zircon. Hafnium, vanadium and chrome, "". '. "'

Pursuant he "severance useful initiators feonnen jiiur 'il'-Ally'üig'fZriden aufwelseru It * ¹ * .but can also eber.i other Lige ends: £ ils present sela- this if desired actual ifi can s; r ^ riise - h-sr; fcational or neutral Matur sela have a mono- or poiya-alanic Ghara'cte ^ / you k: ör ·.) ^ ³ «. BetspielKweise-from the following ?; Ligands be selected ι Mass only c ff-. Hydrogen hydrogen ^ halogen. CarboJt ^ latj Älko ^ · = pb.enolat, ftioifosiolafc, GM °% organtscL'-s Fhospivlne ^ "CO ₅ - N0>olefins; sc: Ltganden» aie see of organic .. B "DxtiarfoonyI- ■ '- •• erblndtirigeri . derivate-ensHow. ? .3 »Ace ^ ylac-eton * jS-C'yanoucetylacefcoiis esters of s ^ K'etoea ^ horxsäuren -so esters of malonic acid ο d er Gy a noma 1 ons Bvcre ₆

Die_ yf-alIylisuhsn compounds can be prepared by the most diverse methods Weyden ^. which ^{are described in the 1} literature. For example, they can thereby be produced;

that one eia.-Metallhalog.enia "or a kompiexietft ^ s Metal halide with a .. 'Aliyl-orignard · = reagent converts, unc! although usually ic.

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BATH ORIGINAL

8 -. ■ '- ■■ ■

It Hird ^l "liervorgeh-ol3en; not -äaß zwange- a single ^ method in heat, can be used for commanding the whole Hörstellung Bereions If-allyli-aahen connections dienen-, -Jedoch can most f ^ ali ^ intermetallic compounds 4urcfe.. one ... ßer-published process oöer .duroh ■ wall 1-ungen. same turn produced ».. ■.: ■" _ ^:

Me products from eggs-mentioned reactions can be isolated. are abeö it is often aweckmäßig that preparations immediately _{prior-.deai.-ßebraueh:} iieE2USt © lXeh and oils solution, di using ^..: - ■■■■ - ■■. - .- ■■ "..-

Care must be taken at all times it / avoid contact -with air and moisture shown below. "In order to prevent einen.Verlust- of catalytic activity Many of the ΙΓ-allylic compounds of the invention are preferably useful feel temperatures below ⁰ ° C. stored

As in the conventional Hoöhdjcuckäthylenpolymerisat-ionsver- · = ".". will drive the temperatures and. DIE bridge * the ver-viendet in dejg ve.rschiedenen zones .-- _s are determined according to the experience or experiment, so that a product with the overall, wished balance of properties arises "Der'Realctions- ■■ - pressure is kept at a predetermined value, and the injection speed of the initiators is controlled in this way *; ' that the reaction in each zone is kept at the specified temperature "-.".

190487a

· = ■ »9» ■.

Provision is made that the compound used is such that at least 3000 moles of ethylene per mole of added initiator at the temperature and pressure selected for the polymerization in the first zone will be present of not raahr than 6 minutes, preferably not more than 2 min and in particular not see more than 30, are converted to polymer in such an initiator services of the remaining initiator in the polymer coming out from the first reaction zone can., effectively without adverse modification of the polymer are destroyed, while the usual processes for the latter part of the polymerization and for the separation of the polymer and conversion into a usable form, e.g. in the form of granules for compression, are carried out,

When Autociavenverfahren was found. That the preferred 'Video- if-aliylisohen initiators of such a nature that the "reaction rate decreases rapidly with time _t when the injection of the initiator is stopped" for a stability of control are those initiators preferred * it allow * that a temperature rise can be stopped within a maximum of 30 seconds if the injection-, des- ". Initiators.-after temperature rise to 1O ⁰ C over the intended temperature türj at which the reaction took place, will be canceled, "initiators that have these properties own" loh for the Verwendunisf in ^ rojtirförmlgen Realctordno

Of the more accessible ^ »allylic. Compounds are the Tris-Cil ^ allyl) and Tr ^> is-C'ff ^ 2-methallyl) charges of chromium and the tetra- ^ - allyl) - and tetra-i5J * '- 2 "methallyl ) "Compounds of zirconium or the monohalogen derivatives of these compounds", such as ZrB. Zirconium-tiPis-C ^ allyD ^ brOffi-idsauo reasons dar- effectiveness as polymerization initiators and their small influence on the chemical nature of the product preferred ", The zirconium compounds ₉ in particular the Zi ^ konallyle _9. Possess presently": Advantage of lower costs "Except @m Zircon is easier to tolerate in the product. The ⁱ 7r'-ailylic compounds can be used alone or optionally with activators ₉ . like S ₁₅ B ₃ organic halides s wis EcBo allyIbromid or propargyl bromide _s vsr-v / ends.

The Tf-alkyl transition metal compound can be injected directly into the first zone of the reactor in a suitable solvent in the same manner as a free radical initiator can be introduced in conventional high pressure ethylene polymerisation processes. Examples of suitable solvents are white fuel _s hydrocarbon oil ₉ - pentane, hexane _s heptane and toluene »The initiator solution is kept by water and air and preferably stored under a nitrogen blanket a before it is introduced» the ethylene for the frozen zone should also include largely secret "water and oxygen". . .. _{^_;;:} "..- '· ..: \ ^■:.:., - - / -

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. ■ _ ι ■ - ■ --- ■ _. ■.

BATH ORIGINAL

JJ's is usually preferred ₉ the free radical generating Xn5 tiator- f or · dip. ^ eJ t * Reaction sane directly into the aweit λ one of the reactor sdr-iswf-ührsn .. Suitable © fr® ie radicals he * de initiators''are aB ,! oi'ganisehß peroxides and. Perests>? A:; onitr-ile wis ^ m ₁ Qy lpe r'O?: Yd- _; . M ~ t ™ b «'tylp®ros £ yä _s ""Di ^ lauroyl · = peroxide«, Di «C 3 _a y _g fi» Tr-ime thyllieitaiioy 1) »peroxide. _f Capr-yIyipe-fOKyö ... 1> »Butylperb € mzoc.t _? t-Du-tylpcsüpaoetsits t ^e butyl "* pej?""t3? iaiethylac © did and Diraethylasociiiirobutyronitrilo piping initiators zeigen- their maximal® Iriitier-uniuswirkung within different .Temperature" = areas, and dHr jeiceilige initiator can be selected v / _s ground that he corresponds to the Bat? iebf / "i;e-uiperatui:" within a certain heaktionszone according to dep normal Pr-aicis "

Kattenübes'tir'agun.gsiaittel can optionally be used in the reaction who> dea _s and swap likewise in accordance with the usual practice, and they are sufficient at least in the "first zone e ^ requirements = lent _B around the molecular weight and thus the -Scliisielaflußindeae of Py * odukts herabsudrücken. "In the absence of Kettenübertrcagungs = - forward yield ⁴ T ^ -» aliy initiators Polymere'mit © Inesi such high molecular weight and such a low Schmeläflußindeass that they are very .schwierig handle co »! A chain transfer means ₉ which is suitable for use together with the Ti ^ AlXyl initiators. _$ , is S ₉ Bi, hydrogen "transferring aioittol. which together with the free radicals generate the initiators can be used _s are SoB * liäsaeretoff _s propane »Prop.flejci ₉

"♦ -Methylpenten" =! ,, cyclohexane and isobutane _o Propylene is to "shining a married & ltnieaässig echwa _C h 's chain transfer agent in the initiated by if-allyl reaction. Accordingly, the chain transfer agents are selected so that the desired degree of chain transfer is achieved in each zone. Depending on their purpose, they can be introduced together into the main stream of the ethylene supplied to the first zone or separately in the two zones.

The one used in the operation of the process according to the invention The reactor can be a stirred continuous reactor, or it can be wholly or partly a continuous tubular Be a reactor that is operated in a known manner '. In the stirred reactor, the stirring is preferably in the first Zone designed in such a way that maximum backmowing occurs, namely through a suitable design of the stirrer · In the second zone and in any other zones that may be present the stirring is preferably carried out in such a way that as far as borrowed any backward movement into the first or into the other " going zones is avoided. The zones are preferably separated by baffles, so that such a back-up is prevented

As already indicated, the ethylene knows completely in the the first zone of the reactor or an additional one

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Ethylene can be introduced into the second or into subsequent zones be ο It is generally preferred that £> a considerable proportion of the total ethylene through the first zone " going to get a substantial amount of polymer with the desired Molecular structure to form in this zone.

The polymer and the unreacted ethylene obtained in the first reactor can be separated in a conventional manner and the unused ethylene can be used for the polymerization reaction «Comonomare can be returned with the ethylene be introduced into each zone if so desired «

The inventive method not only allows the production of polyethylenes with particularly desired flow and narrow elasticity properties ₉ but also creates additional flexibility in the selection of the polymerization conditions in the field of high pressure polymerization of ethylene, so that the desired balance of properties is obtained in the product ». The use of the if-allyl initiators results in the. Formation of a product component j which exhibits greater linearity than can normally be obtained at an economical rate from the high pressure process, thereby increasing the range of stiffness that can be achieved in the product because of the unexpected effectiveness of the m ' -Allylkatalysätoreii at

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the elevated temperatures and elevated pressures, such as are used in the method _s, and because the product is diluted with a free radical-initiated product metal catalyst residues in the product only in low concentrations,

"" ■ - ■■■ "" '.- ■■ - ■ · .---

present 5, which for most normal uses of the product are not harmful "Furthermore, the catalysts of the residues of the ^ -AlIy1" vorausgesetat _s that the presence is avoided corrosive ligands, not such a kind that corrosion of processing equipment in the following use of the product occurs »The presence of the product component initiated by free radicals makes the end products easier to handle and the melt flow index easier to control. Continues to make use of a free radical catalyst in an additional step in the polymerization reaction, it is possible _s higher UmwandlungBgeschwindigkaiten of Äthylenmonomer in polyethylene to achieve _s as if with dan / OrAlIyI-initiators alone could be obtained "

The invention is illustrated by the following examples,, EXAMPLES · -. ...;, -, -: J _f . .; ...--. .. "- _s .- _': v

Initiator for the use in the first son «des tipasreaktors was a solution of zircon-tet ^ akis-II ^ allyl

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either isooctane or tetralin (as indicated in the table)%, it was maintained until the introduction into the first zone of the reactor to a temperature of 10 ⁰ C "The solution also contained either AllyIbromid or Propargylbrömid (as indicated in the table) ₉ which was present for the activation of the zirconium-allyl compound and was present in a sequence ratio of lsi with the zirconium-Ti ^ allyl compound.

Ethylene gas with a content of 1 to 2 mol-t hydrogen as a modifier was pumped into a stirred two-zone reactor is a _"s of the as indicated on © inen pressure of 2000 kg / cm and a temperature (varying in each example)" in the table "The volume of the first zone was twice as high as that of the second zone * In the first zone an ethylene polymerization was brought about by the zirconium-Tf-allyl solution" and a mixture of polymer and non-polymeric stone Ethylene was passed to the second zone, where additional ethylene was added to the reactor to supplement that already polymerized. In the second zone, ethylene polymerization was initiated by the addition of tert-butyl benzoate, which was added at the rate necessary was ₉ to keep the temperature of the second zone at the temperature given in the table «

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The table shows the conditions used in the various examples and also the densities and the catalysts achieved The catalyst performances were in moles of polymerized ethylene per mole of used allyl measured.

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Ex. Dwell time second zone. power Temperature ° C second zone density
g / cm ^ö Solution Activator 8th zone 80 first zone 220 O ₉ 933 BlXttel 1 80 75 ■ 920p 180 250 O ₉ 931 '»Ο · '■, A ..'. 2 80 110 17500 180 250 O ₉ 931 OK ' '' A c 3 _r ■ 115 105 13600 200 · 250 O ₉ 935 ', ok
• 110 120 9800 220 240 O ₉ mo OK · 5 85 135 9500 1.80 240 0.941 ok
■
¹ P.
■ ■ 6 '' 95 125 16700 180 250 O ₉ 341 ι - ¹
• τ. τ ■ ;. 85 110 27600 180 250 0.944. s 75 100 9900 200 240 0.945 T . P- ■ ³ 65 100 8900 220 240 _: O ₉ 94 5 T.; ■ P. 10 70 100 19500 2.00 240 0.94? 10 ". ■ ^p . ■ 70 8700 220 ■■. i-0: ' ■ .. ^p .

OK = isooctane T = tetralin (tetrahydronapiithalin)

As allyl broinide P = propargyl broadd

CD Ö

CO -J 'OQ

Claims (1)

PATENT CLAIMS ι . 1. “Process for the continuous polymerization of ethylene in two or more zones of a continuous reactor, in which the ethylene is passed through a first polymerization zone ... with a pressure of not less than 150 atm and with a temperature of not less than 125 ° C passes, characterized in that raan aine'TT'-Allylübergangsmetallverbindung introducing into said zone 3UR effecting Initiisrung polymerization *, and the reaction mixture of polymer and non-reverse translated "tan ethylene, with or without additional ethylene _s with by aine second polymerization a pressure of at least 1800 atm in the presence of a free radical-generating polymerization initiator, the combined conditions of temperature and pressure in each zone being such that the monomer / polymer reaction mixture exists as the only flowable phase the reaction mixture as a single fluid phase remains _β until it comes out of the called the zone exits. 2ο Verfahrsn according to claim 1 _s characterized ₉ that ■ the temperature in the aswide zone is higher than in the first zone » 3q ^V method fiat claim 1 or -2 _{t s} gekennseichnst characterized in that the T (^ ine Ziffkpnye AlIylübergangsmetallverbindung © ^ biadung is. t. Method according to claim 3, characterized in that the Zirconium compound is zirconium-tris-Cir-allyl) -haloride or zircon-tris- (tf-allyl) -broinid is c 5, method according to claim 1 or 2, characterized in that » daft the if-Allylubergangsmetallverbindurtg together with a organic halide is used. 6. The method according to claim S _9, characterized in »that the organic halide is either an allyl chloride, an allyl bromide, a propargyl chloride or a propargyl bromide, t. ■ 7e method according to any one of the preceding claims _ε characterized in that the V-AlIylübergangeretalverbindungen used is such that at least 3000 mol of ethylene per Mof -Allyl transition ifltttallverbindungen in, the first zone within a dwell time of no more than 6 minutes in polymer 8e method according to claim 7, characterized in that the Dwell time does not exceed 30 seconds. 9ο method according to «inen of the preceding claims, characterized characterized in that the first zone is stirred in such a way that • iß "back-smelling takes place, and d * I in the" veit "zone so g" - It is advised that there will be no return notification. often «« * n, » / a ä PATENTANWäTI ÖIPL | «GlerAiei