KR101040410B1 - A process for transitioning between ziegler natta system and metallocene catalyst system - Google Patents

Abstract

The present invention relates to a process for converting between immiscible polymerization catalyst systems, and more particularly to a process for converting an olefin polymerization reaction using a conventional Ziegler-Natta catalyst system to an olefin polymerization reaction using a metallocene catalyst system. It is about. According to the present invention, by using a deactivator in a minimum amount for various polymerization reactions, not only shortens the time of the conversion process between immiscible catalyst systems, but also facilitates the progress of polymerization of newly introduced catalysts, It is effective in preventing problems such as sheet generation.

Deactivator, Conversion, Ziegler-Natta, Metallocene, Olefin, Unhybridized Catalyst

Description

A PROCESS FOR TRANSITIONING BETWEEN ZIEGLER NATTA SYSTEM AND METALLOCENE CATALYST SYSTEM}

The present invention relates to a process for converting between immiscible polymerization catalyst systems, and more particularly to a process for converting an olefin polymerization reaction using a conventional Ziegler-Natta catalyst system to an olefin polymerization reaction using a metallocene catalyst system. It is about.

Metallocene catalysts are known as catalyst systems for producing polyolefins having excellent physical properties because they have higher activity and higher copolymerization reactivity than conventional Ziegler-Natta catalysts, but have significantly different hydrogen reactivity and copolymerization properties than conventional Ziegler-Natta catalysts. .

When converting between miscible catalysts, there is typically only a slight difference in the reactivity of the miscible catalysts with respect to hydrogen and comonomers, resulting in slight changes in gas phase composition and changes in flow conditions when the catalyst is replaced, The effect on the physical properties of the resulting product is also not significant. However, in the case of immiscible catalysts, due to the different polymerization properties, many process conditions are involved in the conversion between these two catalysts in a commercial reactor, of which the gas phase composition for producing the target polymer is very high for the above reasons. Have a different composition.

Typically, the metallocene catalyst has 100 to 500 times higher hydrogen reactivity and 5 to 10 times higher copolymerizability than the Ziegler-Natta catalyst, and therefore, very low hydrogen upon conversion from the use conditions of the Ziegler-Natta catalyst to the metallocene catalyst. And copolymer composition. In this case, if the Ziegler-Natta catalyst activity remains in the reactor, ultra-high molecular weights are produced at very low hydrogen concentrations, causing gel problems in the product.

To avoid this problem, the conversion between non-hybridized catalysts, such as metallocenes and Ziegler-Natta catalysts, goes through a killing step that stops the reaction of the catalyst in its active state using a killing agent. .

However, since the deactivator remains active in the reactor after use, it inhibits the activity of the newly introduced catalyst. Therefore, the injection of the new catalyst requires a purification step of removing the deactivator to a very low level. After the step of making a suitable gas phase composition to the final step is to inject a new catalyst.

However, this conversion process is very time consuming and expensive, and if the conversion process is unsuccessful, there will be a mixture of ultra high molecular weights that cause gel problems in the bed, making the entire bed unusable. There is a situation where the entire reactor needs to be cleaned.

Excess deactivators may be used to ensure deactivation, but there are certain limitations to using them in excess because they can have the adverse effect of acting as a catalyst poison on the newly introduced catalyst.

On the other hand, the appropriate amount of the deactivator largely depends on the kind of reaction, the kind of catalyst used, the amount of polymer present in the reactor, the form of the polymer and the like. In addition, as described above, in order to remove the deactivator in the next step, an organometallic compound, which is another activator, is used, which causes an overreaction in the reactor when the activator exceeds the appropriate residual amount. This results in sheet formation and fine powder, causing problems such as reactor fouling.

Therefore, the conversion process between the non-hybridization catalysts required an efficient method of using the deactivator and an effective method of removing it after use, and the following prior art exists.

Conventional techniques for the conversion between non-hybridized catalysts, mainly between metallocene catalyst systems and Ziegler-Natta catalyst systems, generally consist of the following steps:

a) discontinuing the injection of the main catalyst and the cocatalyst (eg alkylaluminum);

b) waiting for residual activity to fall below a certain criterion;

c) irreversibly inactivating residual activity using an inactivating agent;

d) removing the deactivator to a level that does not affect the newly introduced catalyst;

e) adjusting the gas phase composition to the operating conditions of the new catalyst;

f) introducing fresh catalyst into the reactor; And

g) determining the success of the conversion process from the polymerization effluent after the introduction of the new catalyst.

Here, the steps a) and b) may be performed sequentially or simultaneously. The deactivator used in step c) uses a compound which acts to lower or stop activity in combination with a promoter or a compound which directly deactivates a catalyst in combination with a catalytically active species. Specific examples include U.S. Patent No. 5,442,019 No., U.S. Patent No. 5,672,665 No., U.S. Patent No. 5,747,612 and U.S. Patent, and the the like reversibly deactivated zero CO, CO ₂ referred to 5,753,786 number, irreversibly disabling zero O _2, H ₂ O , Alcohols and the like are mentioned. In addition, EP 0,107,105 and US Pat. No. 4,460,755 describe examples using compounds containing hydroxy groups, which refers to silicas containing hydroxy groups. U.S. Pat.No. 6,897,269 and European Patent EP 1,576,016 mention nonvolatile materials, which include alkoxylated amines, alkoxylated amides, ethoxylated stearyl amines and the like.

 For step d), most of the patents mentioned above use a purge method after nitrogen pressurization. This step is the most time consuming because, when the deactivator used to deactivate the active catalyst in the bed remains, it acts as a catalyst poison to the newly introduced catalyst, which acts as a barrier to initiating the polymerization reaction. to be. In particular, when the newly introduced catalyst is metallocene, it is very sensitive to the catalyst poison, so the impurity required in this step is mostly less than 1 ppm. Therefore, the removal of the deactivator by nitrogen purge is several tens of times, and it takes a lot of time to inject nitrogen to pressurize the reactor with nitrogen for nitrogen purge. It may be more than 24 hours. In addition, as a method exemplified in US Pat. No. 6,995,217 and US Pat. No. 5,105,926, a method of additionally using alkylaluminum in step d) or f) is provided to remove the deactivator adsorbed in the bed. Excess remaining alkylaluminum is mentioned in US Pat. No. 5,753,786 which causes overreaction with the newly introduced catalyst, causing problems such as sheet formation. Thus, the use of alkylaluminum requires additional nitrogen purge and additional time. To reduce this time requirement, US Pat. No. 5,672,666, EP 0,838,393 and WO 9,639,450 describe a method for starting the introduction of a second catalyst without the use of additional alkylaluminum.

As such, in general, the conventional conversion method takes a very long time in the conversion process, there is no specific reference to the amount of the deactivator injected, and the deactivator is defined as an amount proportional to the remaining catalyst metal component However, in the polymerization reaction, chemicals other than the catalyst participate, and in most cases, the reaction form and the form and amount of the polymer remaining in the reactor are different. Therefore, the prior art has a limit in that it is not a proper solution in the actual case.

The present invention has been made to overcome the limitations of the prior art as described above, the problem to be solved in the present invention is to provide a specific reference for the type and amount of the deactivator used in the conventional non-hybridization catalyst system conversion process I would like to present.

In order to solve the above problems of the present invention, the conversion method of the present invention is a method for converting a polymerization reaction promoted by a first catalyst to a polymerization reaction promoted by a second catalyst which is immiscible with the first catalyst. As

a) mixing and injecting at least one deactivator in the gaseous phase and at least one deactivator in the liquid phase at room temperature to irreversibly deactivate the residual activity of the first catalyst;

b) maintaining the deactivator for at least 6 hours in a reactor maintained above 80 ° C. under flow or stirring;

c) removing said deactivator by nitrogen purge;

d) removing said deactivator by reaction with an organometallic compound;

e) adjusting the gas phase composition to match the operating conditions of the second catalyst;

f) introducing said second catalyst into the reactor; And

g) after injection of the second catalyst, determining whether the conversion process from the polymerization effluent is successful;

 Characterized in that it comprises a.

Here, the second catalyst preferably comprises a metallocene catalyst.

In addition, the first catalyst preferably comprises a Ziegler-Natta catalyst.

Preferably, the gas phase deactivator is carbon dioxide, and the liquid phase deactivator is water.

In addition, the injection amount of each of the gas phase deactivator and the liquid phase deactivator is preferably at least three times the total moles of the metal elements present in the fluidized bed in the reactor in order to achieve sufficient irreversible deactivation.

In particular, the injection amount of each of the gas phase deactivator and the liquid phase deactivator is more preferably 5 to 15 times the total moles of metal elements present in the fluidized bed in the reactor in order to achieve sufficient irreversible deactivation.

In addition, the step b) is preferably a step of maintaining the deactivator for 6 to 10 hours in a reactor maintained at 80 ~ 90 ℃ under flow or stirring.

In addition, the organometallic compound of step d) is of the general formula AlR _(3-a) X _a , wherein R is a branched or linear alkyl or cycloalkyl having 1 to 30 carbon atoms, or a hydride radical , X is halogen, and a is 0, 1 or 2).

Step g),

Iii) a control in which the film was prepared using the polymer before the conversion process, and

Ii) a test group in which a film was prepared using the discharged polymer after the second catalyst injection;

It is preferable to confirm the presence or absence of gel formation in the liver.

In addition, the polymerization reaction is preferably a gas phase process.

According to the problem solving means of the present invention, by using a deactivator in a minimum amount for a variety of polymerization reactions, to shorten the time of the conversion process between the immiscible catalyst system, so that the polymerization reaction of the newly introduced catalyst easily occurs In addition to this, it is effective in preventing problems such as sheet generation.

The present invention allows conversion from one type of catalyst system to an immiscible catalyst system with the use of a minimum amount of deactivator between the minimum periods of the conversion process and occurs in the process of conversion to an immiscible catalyst system. A technique is provided to avoid possible product quality problems (eg gel production) and process problems.

Specifically, the process of the present invention can be applied to conversion between conventional Ziegler-Natta catalysts / catalyst systems and metallocene catalysts / catalyst systems. The terms "catalyst" and "catalyst system" may be used interchangeably herein.

Hereinafter, the present invention will be described in more detail.

Metallocene  Catalyst system

The metallocene catalyst system used in the present invention includes a metallocene catalyst represented by the general formula (THI) ₂ R ″ MQ _p .

In the above general formula, THI is a substituted or unsubstituted tetrahydroindenyl derivative, and R ″ is a structural crosslink that imparts stereo rigidity between two THI groups; M is Group IIIB, IVB, Group VB or Group VIB. Is a transition metal selected from Q is a hydrocarbyl group or halogen having 1 to 20 carbon atoms and p is the valence-2 of M.

In the metallocene catalyst of the general formula, the two THI ligands may be the same or different, but the same is preferable.

Substitution patterns of THI ligands on metallocene catalysts used in the present invention provide the advantages of the present invention. Substitution patterns and numbering of the ligands of the catalyst of the invention are described in detail below.

When THI is substituted, this means that any position on THI may contain a substituent instead of a hydrogen atom. Thus, each substituted THI ligand may have a substituent on the 5-membered ring, a substituent on the 6-membered ring, or a substituent on both 5- and 6-membered rings.

Substituent positions of the THI ligands in the specification of the present invention are numbered 1 to 7 by the following notation system.

In order to distinguish the substitution in the first THI ligand and the second THI ligand of the two THI ligands, the second THI ligand is numbered by the same system as above, but is numbered 1'-7 '. In this type of catalyst, the position of the crosslinking of the two THI ligands is not particularly limited and is preferably 1,1'-crosslinked, 2,2'-crosslinked or 1,2'-crosslinked, 1,1 ' Crosslinking is most preferred.

The position of the substituent (s) on the two THI ligands is not particularly limited, but at least one THI ligand is substituted at the 2-position and / or 4-position (or 2'-position and / or 4'-position) It is preferable.

In one preferred embodiment, both THI ligands can be substituted. In this case, it is preferred to include substituents at the 2-position (2'-position) and / or 4-position (4'-position) of both THI ligands, and to the 2-position (2) of both THI ligands. Most preferably, they include a substituent at the '-position) and the 4-position (4'-position), and other positions in the THI ring may be substituted or unsubstituted.

Particularly preferred metallocene catalysts having 1,1'-crosslinking are 2; 4; 2,4; 2,2 '; 4,4 '; 2,4 '; 2,4,2 '; 2,4,4 '; And a substitution pattern of 2,4,2 ', 4', and only the positions indicated above include substituents. Here, since the basic structure of the two THI ligands is the same, for example, the substitution patterns of 2,4 'and 4,2' are the same THI substituent structure.

When using the above-described metallocene catalyst for producing polyolefin, wherein the THI derivative is substituted by the specific substitution pattern, it has improved physical and mechanical properties, is easy to process, and has excellent optical properties. The polyolefin which has is produced.

Thus, the polyolefin resin produced by the catalyst system of the present invention yields high transparency and solubility while yielding improved processability and solidification properties in injection blow molding and injection molding.

The kind of substituent (s) present on the THI ligand is not particularly limited, and when the THI ligand includes two or more substituents, such THI ligands may be substituted with the same substituents or different substituents.

Preferably, the substituents are independently selected from hydrocarbyl groups, alkyl groups, alkylsilicon groups, alkoxy groups, cycloalkyl groups, aryl groups and halogens having 1 to 20 carbon atoms. Examples thereof include phenyl (Ph), benzyl (Bz), naphthyl (Naph), indenyl (Ind) and benzindenyl (BzInd), methyl (Me), ethyl (Ethyl), n-propyl (n- Pr), i-propyl (i-Pr), n-butyl (n-Bu), t-butyl (t-Bu), trimethylsilicon group (Me ₃ Si), alkoxy (preferably RO, where R is C _1-20 alkyl), cycloalkyl and the like, and halogen. The most preferred substituent at the 2-position of THI is a methyl group. Most preferred substituents at the 4-position of THI are phenyl, naphthyl or benzindenyl.

In one preferred embodiment, examples of THI derivative ligands include 2-Me, 4- PhTHI; 2-Me, 4-NaphTHI; Or 2-Me, 4,5-BzIndTHI.

The type of R ″, which is a crosslinking present between two THI rings in the metallocene catalyst component of the general formula, is not particularly limited, but is preferably an alkylidene group having 1 to 20 carbon atoms, alkyl May be selected from a renyl group, a germanium group (e.g., a dialkylgermanium group), an alkylsilicon group (e.g., a dialkylsilicon group), a siloxane group (e.g., a dialkylsiloxane group), an alkylphosphine group or an amine group, and Most preferably, it is a Renyl radical (-CH ₂ CH _2- ) or Me ₂ Si.

The metal M in the metallocene catalyst of the general formula is a transition metal selected from group IIIB, IVB, VB or VIB of the Periodic Table of the Elements, preferably from Ti, Zr, Hf and V.

Q in the metallocene catalyst of the general formula is preferably halogen, in particular Cl.

And since the valence of the said metal M is four, p becomes 2 normally.

The most preferred metallocene catalyst components used in the present invention are as follows:

Et (THI) ₂ ZrCl ₂ ,

Me ₂ Si (THI) ₂ ZrCl ₂ ,

Me ₂ Si (2-MeTHI) ₂ ZrCl ₂ ,

Et (2-MeTHI) ₂ ZrCl ₂ ,

Me ₂ Si (2-Me, 4-PhTHI) ₂ ZrCl ₂ ,

Et (2-Me, 4-PhTHI) ₂ ZrCl ₂

Me ₂ Si (2-Me, 4-NaphTHI) ₂ ZrCl ₂ ,

Et (2-Me, 4-NaphTHI) ₂ ZrCl ₂ ,

Me ₂ Si (2-Me, 4,5-BzIndTHI) ₂ ZrCl ₂ ,

Et (2-Me, 4,5-BzIndTHI) ₂ ZrCl ₂ .

The catalyst system of the present invention includes, but is not particularly limited to, one or more metallocene catalyst components as described above. Thus, the system may comprise additional catalysts, if desired, for example additional metallocene catalysts or other known catalysts according to the invention. The metallocene catalyst component may be supported on a suitable carrier. Preferred carrier materials are solid particulate porous, preferably inorganic materials, for example oxides of silicon and / or aluminum. In the most preferred embodiment, the carrier is silica in the form of spherical particles, for example spherical particles obtained by a spray drying method.

Examples of such metallocene catalyst / catalyst systems are disclosed in detail in US 5,719,241, US 6,225,251, US 6,432,860, US 6,777,366, US 6,855,783, US 7,127,853, US 7,041,756 and US 7,127,853. In addition, the supported metallocene catalyst component is described in W. Spalek; A. Antberg, J. Rohrmann, A. Winter, B. Bachmann, P. Kiprof, J. Behm, and W. A. Hermann, Angew. Chem. Int. Eng. Ed. 1992, 31, 1347, or commercially available from mCAT GmBH (Geschuftfuhrer Dr Markus Ringwald Handelsregister Freiburgi HRB 381812).

Conversion process

The conversion process of the present invention is carried out according to the following steps.

a) irreversibly deactivating the residual activity of the first catalyst using an inactivating agent

In order to stop the polymerization of the first immiscible catalyst, the introduction of the catalyst into the reactor is stopped. However, since the remaining catalyst in the bed maintains activity, the polymerization reaction is continued under gaseous reaction conditions. Over time, these activities decrease rapidly but are not completely inactivated. Thus, they need to be completely deactivated by the deactivator.

Deactivators used in the present invention are catalyst breakers or inhibitors that deactivate the ability of the catalyst to polymerize olefins. Deactivators of the present invention are, for example, water, carbon dioxide, sulfur dioxide, sulfur trioxide, glycols, phenols, ethers, carbonyl compounds, for example ketones, aldehydes, carboxylic acids, esters, fatty acids, alkynes such as acetylene, amines, Organic halides such as nitrile, nitrogen compounds, pyridine, pyrrole, carbonylsulfide, carbon tetrachloride and mercaptans, but are not limited to these. It is important that the deactivator does not contain oxygen or alcohol, because the use of a compound such as alcohol adheres the polymer fines to the walls of the reactor, which in turn generates reactor sheeting.

It is also within the scope of the present invention that this deactivator is used in any mixture, but it is advantageous to introduce them separately, as some of these deactivators may react with each other.

In a preferred embodiment of the process of the invention, if the first immiscible catalyst feed is stopped, the deactivator is introduced into the reactor for a period of time sufficient to substantially deactivate the catalyst in the reactor and thus substantially no polymerization takes place. When carrying out the process of the present invention in a reactor where the polymerization is carried out using the first catalyst, the use of deactivators reduces the likelihood of seating and / or contamination of the reactor.

Preferred deactivators in the present invention are carbon dioxide which is gaseous at room temperature and water which is liquid at room temperature. Carbon dioxide has a reversible deactivator for the catalyst but an additional effect of stopping the alkylaluminum as a promoter in an irreversible reaction for the alkylaluminum. Water has an irreversible deactivation effect on both the catalytic transition metal component and alkylaluminum, but it is not easily removed compared to carbon dioxide in the deactivator removal step, so it is necessary to use both carbon dioxide and water effectively.

The amount of deactivator varies depending on the size of the reactor, the amount and type of catalysts and promoters in the reactor, and the amount and type of polymer. The minimum amount of deactivator used is important. Since the deactivator needs to be removed before the introduction of the second immiscible catalyst, the use of unnecessary deactivators would rather hinder the conversion process.

In a preferred embodiment, the deactivator of the present invention is used in an amount based on the Al atom of the alkylaluminum, which is an activator present simultaneously with all the atoms of the catalytic transition metal component in the reactor. Since most of the deactivators used are adsorbed on the polymer or react with alkylaluminum, calculation of the amount of deactivator considering only the catalytic transition metal results in insufficient effective usage. Therefore, the injection amount of each of carbon dioxide and water is preferably three times or more, preferably 5 to 15 times, the sum of the moles of alkyl aluminum and the total metal elements constituting the first catalyst in the reactor.

b) maintaining the deactivator in the reactor

Sufficient time is required for the deactivator to be dispersed throughout the reactor, in particular throughout any polymer product in the reactor. Once the deactivator has been introduced into the reactor, the time to maintain in the reactor is preferably at least 6 hours, more preferably 6 to 10 hours. This duration may vary depending on the nature and amount of the catalyst, the volume of the reactor, the reactivity of the deactivator and the amount of bed. Thus, for this reason it is preferred that the deactivator is gas or vapor at reactor conditions. Therefore, it is desirable to use at least one deactivator that is gaseous at room temperature, and it is desirable to maintain the temperature in the reactor at least 80 ° C., preferably 80-90 ° C., so that the most powerful deactivator, water, becomes gas in the reactor as much as possible. However, the problem that the gel occurs after the conversion process is out of the temperature range is not greatly improved.

c) deactivator removal by nitrogen purge

The deactivator should be effectively removed after playing a role in eliminating the catalytic activity in the fluidized bed. Carbon dioxide is easily removed by nitrogen purge, but moisture is not easily removed by nitrogen purge. In addition, the moisture adsorbed to the fluidized bed polymer will continue to affect the new catalyst introduction step to act as a factor that inhibits the activity. Therefore, in this step, the step of removing the deactivator by the organometallic compound may be optionally performed later. The nitrogen purge is generally performed by repeating pressurization and depressurization, and the pressurization and depressurization is between 20 and 1 bar, and preferably in the range between 10 and 3 bar. The nitrogen purge is carried out 10 to 20 times, and the criterion for completion is less than 1 ppm of inert material in the degassing gas. The pressurization of the gas phase polymerization reactor to the pressure takes several tens of minutes, the entire purge step requires a time of about 6 hours to 12 hours.

d) removing the deactivator by the organometallic compound

Organometallic compounds that are activators or eliminators used in this step are, for example, BX ₃ , R ₁ R ₂ Mg, ethylmagnesium, R ₄ CORMg, RCNR, ZnR ₂ , CdR ₂ , LiR, SnR ₄ (here, X is halogen, and each R group is a hydrocarbon group which may be the same or different. Other organometallic compounds typically used are alkyl, alkoxide and halide compounds of organometals of groups I, II, III and IV. Preferred organometallic compounds used are lithium alkyl, magnesium or zinc alkyl, magnesium alkyl halides, aluminum alkyls, silicon alkyls, silicon alkoxides and silicon alkyl halides, more preferably aluminum alkyls and magnesium alkyls.

In one embodiment, preferred organometallic compounds are of the formula AlR _(3-a) X _a , wherein R is branched or linear alkyl or cycloalkyl having 1-30, preferably 1-10 carbon atoms, Or a hydride radical and X is a hydrocarbyl aluminum of halogen, for example chlorine, bromine or iodine, preferably chlorine and a is 0, 1 or 2. The most preferred organometallic compounds are aluminum alkyls such as triethylaluminum (TEAL), trimethylaluminum (TMAL), triisobutylaluminum (TIBAL) and tri-n-hexylaluminum (TNHAL), and removers, activators Or the most widely used alkylaluminum as both are TEAL and TiBA.

After the organometallic compound is used, a nitrogen purge step is performed to remove the reactants with the deactivator and the unreacted organometallic compound itself. This nitrogen purge is carried out under the same conditions as the nitrogen purge for removing the deactivator.

e) adjusting the gas phase composition to the operating conditions of the new catalyst;

After completion of the nitrogen purge step, a gas phase composition is constructed to suit the operating conditions suitable for the new catalyst. In order for a particular catalyst to produce a specific product with a specific density and melt index (which generally depends on how well the catalyst binds to the comonomer), a specific gas composition must be present in the reactor.

The gas composition generally comprises one or more monomers comprising ethylene alone or together with one or more linear or branched monomers of 3 to 20 carbon atoms, preferably 3 to 12 carbon atoms. The process of the invention comprises ethylene and one or more monomers such as propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, decene-1, styrene and cyclic and polycyclic olefins. It is particularly well suited for gas compositions comprising together alpha-olefin monomers of, for example, cyclopentene, norbornene and cyclohexene or mixtures thereof. Other monomers used with ethylene include polar vinyl monomers, diolefins such as 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, norbornene, norbornadiene, and acetylene, There are other unsaturated monomers, including 1-alkyne and aldehyde monomers. Higher alpha-olefins and polyenes or macromonomers can also be used. Preferably the comonomer is an alpha-olefin having 3 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, most preferably 4 to 10 carbon atoms.

In another embodiment the gas composition contains ethylene together with two or more other comonomers to form terpolymers and the like, with the preferred comonomers optionally having 3 to 10 carbon atoms, more preferably having one or more diene monomers. It is a combination of alpha-olefin monomers having 3 to 8 carbon atoms. Preferred terpolymers are ethylene / butene-1 / hexene-1, ethylene / propylene / butene-1, ethylene / propylene / hexene-1, ethylene / propylene / norbornadiene, ethylene / propylene / 1,4-hexadiene and the like. Combinations.

Typically, the gas composition contains a certain amount of hydrogen to control the melt index of the resulting polymer. In a typical situation the gas comprises a certain amount of dew point increasing component, and the remaining amount of the gas composition consists of a non-condensable inert gas such as for example nitrogen. Depending on the second catalyst introduced into the reactor, gaseous compositions such as concentrates of comonomers and hydrogen gas can be increased or decreased. When the metallocene catalyst system is a novel catalyst, the ethylene / hydrogen molar ratio is 1/100 to 1/500 relative to the Ziegler catalyst, and the ethylene / copolymer molar ratio is in the range of 1/5 to 1/10.

f) introducing fresh catalyst into the reactor

When the gas phase composition reaches a level suitable for the new catalyst, a new catalyst is injected. In this case, in order to activate the newly introduced catalyst, appropriate organometallic compounds may be injected simultaneously or sequentially. The organometallic compound to be used is in the range of 1 to 2000 times, preferably 10 to 1000 times and most preferably 100 to 500 times by mass molar ratio of the transition metal of the catalyst.

g) determination of the success of the conversion process from the polymerization effluent after injection of the new catalyst into the reactor;

When a new catalyst is injected and the polymerization reaction proceeds to produce a new polymer, a portion of the fluidized bed begins to discharge to the reactants to maintain a constant fluidized bed. The initial effluent contains most of the polymer prior to the conversion rather than the polymer with the new catalyst, which contains the deactivated residual catalyst. Emissions from a successful conversion process contain the same level of gel in the gel evaluation as before the conversion process, but if the conversion process fails, a large amount of gel will be produced in the emission evaluation. If this problem occurs, the entire fluidized bed cannot be used as a product, and a new reaction to form a clean bed must be carried out, so that the conversion process cannot be newly performed at this point. The present invention provides a technique for solving such a problem.

Preparation of Olefin (Co) polymers

After the introduction of the metallocene catalyst as a new catalyst and the successful conversion of the catalyst system, the composition comprising hydrogen, olefins and comonomers is reacted in the presence of the metallocene catalyst as the main catalyst to react the olefin polymer and the air. The coalescing process is carried out.

In the method for producing an olefin (co) polymer according to the present invention, the metallocene catalyst is preferably combined with one or more activators to form an olefin-polymerization catalyst system. Preferred activators include alkylaluminum compounds (e.g. diethylaluminum chloride), aluminoxanes, modified aluminoxanes, neutral or ionic ionizing activators, noncoordinating anions, noncoordinating Group 13 metals or metalloid anions, boranes, borate salts and the like. have.

With the alkyl aluminum compound has the general formula AlR _n X _(3-n) alkyl aluminum compounds represented by (wherein, R is an alkyl group of carbon number 1 ~ 16, X is a halogen element, and 1≤n≤3) Can be used. Specific examples of the alkyl aluminum compound are preferably triethyl aluminum, trimethyl aluminum, trinormal propyl aluminum, trinormal butyl aluminum, triisobutyl aluminum, trinormal hexyl aluminum, trinormal octyl aluminum, tri2-methylpentyl Aluminum and the like are used, and particularly preferably triisobutylaluminum, triethylaluminum, trinormalhexylaluminum or trinormaloctyl aluminum is used.

The alkylaluminum compound is preferably used at the time of gas phase polymerization in the range of 1 ≦ alkylaluminum compound / transition metal ≦ 1,000 in the main catalyst, more preferably 10 ≦ alkylaluminum compound / main catalyst, depending on the desired polymer properties. Metal≤300. If the molar ratio of the transition metal in the alkylaluminum compound / main catalyst is less than 1, sufficient polymerization activity cannot be obtained, whereas if it exceeds 1,000, the adverse effect of lowering the polymerization activity appears.

In such a method for producing an olefin (co) polymer, the polymerization reaction is carried out in the absence of a hydrocarbon solvent, preferably at a temperature of 60 to 120 ° C, more preferably at 65 to 100 ° C, even more preferably at a temperature of 70 to 80 ° C. Preferably it is carried out by gas phase polymerization at a pressure of 2 to 40 atmospheres, more preferably 10 to 30 atmospheres.

If the polymerization temperature in the reactor is less than 60 ° C., sufficient polymerization efficiency cannot be obtained. If the polymerization temperature is more than 100 ° C., there is a problem that a polymer mass is easily generated. In addition, when the operating pressure in the reactor is less than 2 atm, the ethylene partial pressure is low to obtain sufficient polymerization efficiency. When the operating pressure exceeds 40 atm, control of the reaction becomes difficult, and the reactor is exerted.

Polymerization Process

The process of the present invention can be used in gas phase, liquid phase, slurry or bulk phase polymerization processes. In particular, a gas phase polymerization process in a fluidized bed reactor is preferred. The gas phase fluidized bed reactor is described below in detail. In a typical continuous gas fluidized bed polymerization process, the gas phase flow, including the monomers for the polymerization reaction, is passed through a fluidized bed reactor (2 in FIG. 1) under reaction conditions in the presence of a catalyst. Some of the monomers included in the gaseous stream are brought into contact with the catalyst and the polymer being polymerized to participate in the polymerization reaction, and the unreacted monomers are heated to the upper part of the flow reactor (Fig. 1) by the heat of polymerization, and the compressor (Fig. 1) 4) and the freezer (3 in FIG. 1) and circulated to the fluidized bed reactor. Hydrogen, a consumed monomer and molecular weight distribution regulator, is injected into this gaseous circulation stream. The catalyst component is injected directly into the fluidized bed by a suitable method and the resulting polymer is withdrawn from the fluidized bed.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[ Example ]

Example

1. Support Metallocene  Preparation of the catalyst

Et (THI) ₂ ZrCl ₂ , a catalyst component of the present invention, was used by purchasing a compound sold by mCAT. The carrier used Grace XPO-2402 silica.

5 g of the silica was suspended in a round bottom flask equipped with a magnetic stirrer, a nitrogen inlet and a dropping funnel.

In order to produce an activated catalyst, about 0.3 g of the catalyst was reacted with 25 ml of methylaluminoxane (30 wt% MAO in toluene) at a temperature of 25 ° C. for 10 minutes to provide the corresponding metallocene cation and anionic methylaluminoxane oligomer. The solution of was calculated. The solution containing the resulting metallocene cation and anionic methylaluminoxane oligomer was replaced by a reflux condenser under nitrogen, immediately dropwise with a funnel and added to the suspended silica. The mixture was heated to 110 ° C. for 90 minutes. The reaction mixture was then cooled to room temperature, filtered under nitrogen and washed with toluene. Thereafter, the obtained catalyst system was washed with pentane and then dried under mild vacuum.

The catalyst was used by direct injection into a fluidized bed reactor in a dry state.

2. Ziegler Appear  Preparation of the catalyst

A 1 liter glass reactor equipped with a mechanical stirrer, reflux condenser and heating or cooling device was filled with dry nitrogen, followed by 12.15 g (500 mmol) of powdered magnesium, 23.75 g (125 mmol) of titanium tetrachloride, and 92.5 g (n-butyl chloride). 1 mol) and n-heptane in an amount such that the total capacity is 600 ml were continuously introduced at ambient temperature.

After adding 1.26 g of iodine, the reaction medium was heated to 75 ° C. with stirring to initiate the reaction. If the reaction started slowly after about 1 hour and 30 minutes, the reaction medium was maintained at 75 ° C. for 3.5 hours. The resulting brown / black precipitate was washed several times with heptane. The weight composition ratio of the obtained Ziegler-Natta catalyst was as follows.

Ti: 10.3%, Mg: 19.2%, Cl: 70.5%

3. Ziegler Nata Prepolymer  Preparation of the catalyst

In a 5 L stainless steel reactor equipped with a mechanical stirrer, 2 L of n-heptane was introduced at ambient temperature under nitrogen atmosphere. After heating n-heptane to 70 ° C., a Ziegler-Natta catalyst prepared in 2. above was introduced in an amount corresponding to 0.46 g (4 mmol) of triethylaluminum and 1 mg of titanium atoms.

When the reaction medium was heated to 75 ° C., hydrogen was introduced until the pressure was 0.6 MPa and then ethylene was introduced at a throughput of 160 g / hr.

After 7 hours from the start of the polymerization, 1,100 g of a Ziegler-Natta type prepolymer catalyst having a titanium content of 34 ppm were obtained.

4. Vapor polymerization method in fluidized bed

The gas phase polymerization method using the Ziegler-Natta prepolymerization catalyst prepared in 3. was carried out under the Ziegler-Natta polymerization conditions of Table 1 using the gas phase polymerization reactor of FIG.

Reaction conditions Ziegler Nata Metallocene Temperature (℃)
Pressure (kgG / ㎠)
Ethylene (mol%)
Hydrogen (mol%)
Hydrogen / ethylene ratio
Comonomer (mol%)
Comonomer / ethylene ratio
Bed weight (kg)
Retention time (hr)
Yield rate (kg / hr)
MI
density
Bulk Density (g / cc) 80
19.2
50
10
0.2
20
0.4
70
11.7
6
One
0.92
0.34 80
19.2
30
0.03
0.001
0.39
0.013
70
11.7
6
One
0.917
0.46

5. Conversion process

a) inactivating step

The conversion process was started in the steady state of the gas phase polymerization process using the Ziegler-Natta catalyst of the above 4.

First, the introduction of the Ziegler-Natta prepolymer was stopped, and the reaction was stopped by injecting carbon dioxide. The injection amount of carbon dioxide was 7 times the sum of the moles of the Ziegler-Natta catalyst and the metal element of triethylaluminum present in the fluidized bed. Thereafter, additional water was injected after maintaining a circulating flow for 1 hour. The amount of water injected was five times the sum of the moles of the Ziegler-Natta catalyst and triethylaluminum metal element present in the fluidized bed.

b) inactivation step

The gas circulation flow was maintained for 7 hours after the water injection. At this time, the temperature of the fluidized bed reactor was maintained at 80 ℃, the pressure was maintained at 19.2kg / cm ² .

c) deactivator removal by nitrogen purge

The nitrogen pressurized purge of the gas phase fluidized bed reactor was carried out 20 times at a pressure of 3 to 9 kgf / cm ² . The nitrogen pressurized purge took 12 hours and after completion the CO ₂ and water residuals in the reactor were measured. As a result, CO ₂ was measured to be less than 1 ppm and moisture of 5 to 7 ppm.

d) removing the deactivator by alkylaluminum

 0.65 L TiBA (0.2M) was injected and circulated for 4 hours. After maintaining the circulating flow, the fluidized bed reactor was subjected to a nitrogen pressurized purge ten times under the same conditions as in the previous step. After completion of the run, the moisture measurement resulted in less than 1 ppm.

e) formation of gas phase composition for new catalysts

Thereafter, monomer and hydrogen were injected to adjust to the gas phase composition for the metallocene catalyst.

The gaseous composition for the metallocene was composed of 0.03 mol% for hydrogen, 30 mol% for ethylene, 0.39 mol% for comonomers, and the rest was filled with nitrogen as shown in Table 1 above.

f) new catalyst injection step

Thereafter, after the gas phase composition reached the target value, the supported metallocene catalyst prepared in 1. was injected to initiate the reaction. When the polymerization reaction proceeded and the bed level started to rise, the discharge of the prepared ethylene copolymer was started.

g) determining whether the transition process is successful

The ethylene copolymer resin prepared in f) was granulated to form a film, and gel evaluation was performed as follows to determine whether the conversion process was successful.

Films for gel evaluation were made using HAKKE (Thermo Scientific). Gel levels were determined by visual grade and designated from 1 to 8. The number of gels was determined to increase as the step went up. In the case of steps 1 to 3, it is the gel level of the film used commercially, and 6 or more steps are impossible to use as a film. In order to confirm gel formation by the residual catalyst during gel evaluation, a fluidized bed seed before the conversion process is taken to produce a film without any further process, and gel evaluation is performed to confirm the base value of the gel. It was. The results are shown in Table 2 and FIG. 2.

Comparative example  One

The conversion process was carried out in the same manner as in the embodiment, except that the amount of the deactivator used in the conversion process was used in half of the embodiment. The results are shown in Table 2 and FIG. 3.

Comparative example  2

The conversion process was carried out in the same manner as in the embodiment, except that the retention time after injection of the deactivator was reduced to 4 hours unlike the embodiment. The results are shown in Table 2 and FIG. 4.

Comparative example  3

The conversion process was carried out in the same manner as in the embodiment, except that the temperature during maintenance after injection of the deactivator was lowered to 50 ° C. unlike the embodiment. The results are shown in Table 2 and FIG. 5.

Comparative example  4

Without injection of CO ₂ and water as deactivators in the conversion process, stop the injection of the Ziegler-Natta catalyst and stop the reaction by removing the gas phase composition of the Ziegler-Natta catalyst system by nitrogen purge, and after forming the operating conditions to the metallocene gas phase composition, The polymerization was carried out in the same manner as in Example using a strong catalyst. Gel evaluation was performed on the powder of the prepared ethylene copolymer. The results are shown in Table 2 and FIG. 6.

Example Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Seed bed weight (kg) 70 70 70 70 70 CO ₂ Usage (g) 250 125 250 250 - H ₂ O Usage (g) 65 30 65 65 - [CO ₂ ] / [metal element] (mol / mol) 7 One 7 7 - [H ₂ O] / [metal element] (mol / mol) 5 One 5 5 - Retention time (hr) 7 7 4 7 - Temperature (℃) 80 80 80 50 - Seed Bed Gel Evaluation (Steps) 3 3 3 3 3 Gel Evaluation After Conversion Process (Step) 3 7 5 6 8

As can be seen in Comparative Examples 1 to 3, it can be seen that the gel formation due to the residual catalyst increases as the amount of the deactivator used, the holding time, and the holding temperature are changed. In addition, as can be seen from Comparative Example 4, it can be seen that in the case of the conversion process without the deactivator, a very large gel is formed in different gas phase compositions due to the activity of the residual catalyst.

1 is a gas phase polymerization process chart.

2 is a film photograph of the embodiment.

3 is a film photograph of Comparative Example 1.

4 is a film photograph of Comparative Example 2.

5 is a film photograph of Comparative Example 3.

6 is a film photograph of Comparative Example 4.

Claims (10)

A method of converting a polymerization reaction promoted by a Ziegler-Natta catalyst into a polymerization reaction promoted by a metallocene catalyst which is immiscible with the Ziegler-Natta catalyst, a) mixing injecting a deactivator consisting of gaseous carbon dioxide and liquid water to irreversibly deactivate the residual activity of the Ziegler-Natta catalyst; b) maintaining the deactivator for at least 6 hours in a reactor maintained above 80 ° C. under flow or stirring; c) removing said deactivator by nitrogen purge; d) Formula AlR _(3-a) X _a , wherein R is a branched or linear alkyl or cycloalkyl having 1 to 30 carbon atoms, or a hydride radical, X is halogen, a is 0 , 1 or 2) to remove the deactivator by reaction with the organometallic compound; e) adjusting the gas phase composition according to the operating conditions of the metallocene catalyst; f) introducing said metallocene catalyst into the reactor; And g) after injection of the metallocene catalyst, determining whether the conversion process from the polymerization discharge is successful;  Method comprising a. delete delete delete The method of claim 1, wherein the injection amount of each of the gaseous deactivator, carbon dioxide, and the liquid deactivator, water, is at least three times the total moles of the total metal elements present in the fluidized bed in the reactor to achieve irreversible deactivation. . The method of claim 5, wherein the injection amount of each of the gaseous deactivator carbon dioxide and the liquid deactivator water is 5 to 15 times the total number of moles of the metal element present in the fluidized bed in the reactor to achieve irreversible deactivation. Way. The method of claim 1 wherein step b) is characterized in that the step of maintaining the deactivator for 6 to 10 hours in a reactor maintained at 80 ~ 90 ℃ under flow or stirring. delete The method of claim 1, wherein step g) Iii) a control in which the film was prepared using the polymer before the conversion process, and Ii) Test group which produced film using discharge polymer after metallocene catalyst injection A method characterized by the fact that the presence of gel formation in the liver. The method of claim 1, wherein the polymerization reaction is a gas phase process.

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