KR100310758B1 - Manufacturing method of granular resin - Google Patents

Abstract

The present invention relates to a method for producing a granular resin, which method comprises dispersing a catalyst containing a support, a transition metal and aluminum in an alkane solvent zone under substantially anhydrous state to form a slurry in the reaction vessel stand; Maintaining the slurry at an absolute pressure of 1,000 psi (6.9 MPa) and a temperature of 20 ° C. to 100 ° C .; Introducing an olefin having a partial pressure of 20 to 1000 psi (0.14 sow 1 6.9 MPa) and an alpha olefin containing 3 to 10 carbon atoms into the reaction vessel; And recovering the granular resin having a bulk density of 15 site 36 1b./ft ³ (240 to 580 kg / m 3), specific gravity of 0.98 g / cc or less, and MFR (melt flow ratio) of about 30 It includes.

Description

[Name of invention]

Process for producing granular resin

Detailed description of the invention

The present invention relates to a method for producing granular resin.

In particular, the present invention relates to a slurry process for the polymerization and copolymerization of ethylene in the presence of a supported catalyst containing a metallocene of a transition metal.

The use of metallocene compounds of transition metals as catalysts for the polymerization and copolymerization of ethylene has been used relatively recently in the polymerization and copolymerization reactions.

Metallocene can be represented by the empirical formula Cp _m MA _n B _p . Together with alumoxane these compounds have been used to prepare olefin polymers and copolymers, such as ethylene and propylene homopolymers, ethylene-butene and ethylene-hexene copolymers (see, for example, U.S. Pat.

Methylalumoxane (MAO) is used as cocatalyst with a metallocene catalyst. It belongs to alumoxanes comprising oligomeric linear and / or cyclic alkyl alumoxanes represented by the general formula:

R- (Al (R) -O) _n -AlR ₂ (for oligomeric linear alumoxane) and (-Al (R) -O-) _m (for oligomeric cyclic alumoxane)

[Wherein n is 1 to 40, preferably 10 to 20: m is 3 to 40, preferably 3 to 20: and R is a C ₁ -C ₈ alkyl group, preferably methyl]

Methylalumoxane is prepared by reacting trimethylaluminum with water or a hydrated inorganic salt such as CuSO ₄ .5H ₂ O or Al ₂ (SO ₄ ) ₃ .5H ₂ O. Methylalumoxane can also be produced by adding trimethylaluminum and water or hydrous inorganic salts in the polymerization reactor itself.

MAO is a mixture of oligomers with a very wide molecular weight distribution, with an average molecular weight of usually about 1200. Typically, MAO is stored in toluene solution.

In existing commercial slurry processes, attempts to produce LLDPE have been unsuccessful because polymer and / or catalyst solubility limits yield and also hampers efficient, solvent separation and solid transfer downstream of the reactor.

First, when the polymer is soluble in the solvent, the soluble fraction typically expands to limit the polymer content per unit reactor or solvent volume, thus limiting the rate of production. In addition, the resulting gel-like structure tends to contaminate the reactor. As a result, a resin whose bulk density is unacceptably low is produced.

Second, when the catalyst is soluble in a solvent or monomer, the polymer chains grown from the catalyst retain unacceptable particle form. The resin from the soluble catalyst fraction is very small particles (“fine particles”) that expand in the solvent to form a gel-like structure.

The present invention provides an answer to these limitations. By reacting the metallocene / MAO solution with the reactive surface of the support, a new class of catalyst is formed. Under controlled conditions, this new class of catalysts provides a good form of polymer without the above problems.

According to the present invention there is provided a method of forming a granular resin comprising the following steps:

(a) dispersing a catalyst comprising a support, a transition metal and aluminum in a solvent in a substantially anhydrous state to form a slurry in the reaction vessel;

(b) maintaining the formed slurry at an absolute pressure of 1000 psi (6.9 MPa) or less and a temperature of 20 ° C. to 100 ° C .;

(c) introducing an ethylene having a partial pressure of 20 psi to 1000 psi (0.14 MPa to 6.9 MPa) and an alpha olefin having 3 to 10 carbon atoms into the reaction vessel; And

(d) granular resins having a bulk density of 15 lb / ft ³ to 26 lb / ft ³ (240 kg / m ³ to 580 kg / m 3), specific gravity less than 0.98 g / cc, MFR (melt flow ratio) less than about 30; Recovering.

In step (d) it is advantageous to copolymerize ethylene and alpha olefins to form granular resins which are almost insoluble in the solvent and have an average particle size of 300 μm to 800 μm.

The specific gravity is preferably less than 0.94, most preferably less than 0.93.

In a preferred embodiment, the support is amorphous, porous and comprises silica having a pore volume of 0.1 cc / g to 5 cc / g, wherein the silanol group concentration of the silica is preferably less than 2.5 mmole per gram of silica.

It is also desirable to contact the silica with a constant volume of the mixture comprising metallocene and aluminoxane, wherein the volume of the mixture is less than or equal to the total pore volume of the dehydrated silica.

Preferred general formulas of the metallocenes are Cp _m MA _n B _{p where} Cp is a substituted cyclopentadienyl group; m is 1 or 2; M is zirconium or hafnium; A and B are each halogen atoms, Is selected from the group consisting of a hydrogen atom and an alkyl group: and m + n + p is the same as the valence of the metal M; Alumoxane is represented by the following general formula (a) or general formula (b); The contacted silica is an activated catalyst: (a) R- (Al (R) -O) n-AlR ₂ (for oligomeric linear alumoxane) (b) (-Al (R) -O-) m (For oligomeric cyclic alumoxanes), where n is 1 to 40: m is 3 to 40 and R comprises a C ₁ -C ₈ alkyl group.

The catalyst is preferably in the form of particles having a particle size of 1 μm to 500 μm.

The ratio of aluminum to transition metal in the catalyst is preferably about 70 to about 350.

The amount of transition metal (based on elements) is 0.001% to 10% by weight, and the amount of aluminum (based on elements) is 1% to 40% by weight; Al: transition metal ratio (elemental basis) is 25 to 10,000.

The catalysts are bis (n-butylcyclopentadienyl) metal dihalide, bis (n-butylcyclopentadienyl) metal hydridohalide, bis (n-butylcyclopentadienyl) metal monoalkyl monohalide, bis (n It is preferred to include a metallocene selected from the group consisting of -butylcyclopentadienyl) metaldialkyl, bis (tetrahydroindenyl) metal halides and bis (indenyl) metal dihalides. More preferably, the catalyst is bis (isobutylcyclopentadienyl) zirconium dichloride, bis (pentamethylcyclopentadienyl) zirconium dichloride, bis (tetrahydroindenyl) zirconium dichloride, bis (indenyl) zirconium Consisting of dichloride, bis (1,3-dimethylcyclopentadienyl) zirconium dichloride, bis (methylcyclopentadienyl) zirconium dichloride, and bis (n-butylcyclopentadienyl) zirconium dichloride Metallocenes selected from the group.

Preferred solvents are alkanes, in which case the alpha olefins in the solvent preferably give a concentration of 0.1% to 50% by weight, more preferably 0.1% to 30% by weight.

Alkanes preferably contain 4 to 19 carbon atoms. Most preferred solvents are selected from the group consisting of isobutane, pentane, isomers of pentane, hexanes, isomers of hexane, heptanes, isomers of heptane, octane, isomers of octane, decane, dodecane and mixtures thereof.

The preferred boiling point of the solvent is below 180 ° C.

In step (b), the pressure is preferably less than 600 psi (4.1 MPa).

Slurry Process Condition

The catalyst is dispersed in the solvent under stirring. Stirring is carried out throughout the polymerization reaction (or copolymerization reaction) by conventional means. The polymerization reaction is carried out in anhydrous state.

The slurry catalytic polymerization reaction of the present invention is carried out at a total pressure of less than about 1000 psi (6.9 MPa). Generally, the total pressure is from 20 psi to 1000 psi (0.14 MPa to 6.9 MPa), with 100 psi to 600 psi (0.69 MPa to 4.1 MPa) more preferred.

The ethylene partial pressure is from about 20 psi to about 1000 psi (0.14 MPa to 6.9 MPa), with preferably about 60 psi to about 600 psi (0.41 MPa to 4.l MPa). If necessary, hydrogen may be added to the slurry polymerization reaction. The hydrogen partial pressure is from 0 psi to 20 psi (0 MPa to 0.14 MPa), preferably less than 10 psi (0.069 MPa).

The temperature of the catalytic polymerization reaction is 25 ° C. to 100 ° C .; The upper limit depends on the solvent. The temperature for preparing a resin having a specific gravity less than about 0.94 may be as low as 90 ° C., such as 40 ° C. to 45 ° C. A temperature of 55 ° C. to 75 ° C. is preferred at a pressure of about 125 psi (0.86 MPa), with about 60 ° C. to about 70 ° C. being most preferred. The residence time can be 1 hour to 4 hours. Under these conditions, particulate polymers are formed in the solvent in the slurry reactor. The average particle size of the product in the slurry reactor is from 300 μm to 800 μm. Typically, the average particle size of the product in the slurry reactor is between 450 μm and 650 μm.

The solvent is usually an aliphatic solvent. Aliphatic compounds or mixtures thereof have from 4 to less than 20 carbon atoms and are preferably straight or branched chain alkanes or mixtures thereof having a maximum boiling point of less than 180 ° C, preferably less than 150 ° C. Typical solvents include isobutane, pentane and isomers thereof, hexanes and isomers thereof, heptanes and isomers thereof, octane and isomers thereof. Petroleum fractions, usually containing these compounds as a mixture, can also be used.

In the experiments herein, the slurry contains from 0.0047% to 0.01175% of catalyst in 1000 cc of solvent or from 40 mg to 100 mg of catalyst in 1000 cc of solvent. Typically, the reaction is carried out with 70 mg of catalyst per 1000 cc.

When producing low density resins with specific gravity less than about 0.94, comonomers are alpha-olefins having 3 to 10 carbon atoms for copolymerization with ethylene. The concentration of the alpha olefin in the solvent is 0.1% to 50% by weight, preferably 0.1% to 30% by weight, with about 10% by weight being most preferred. Alpha olefins having 3 to 10 carbon atoms include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene. Most preferred are alpha olefins having 6 to 8 carbon atoms.

[Preferred Catalyst Composition]

Preferred anhydrous (water free, intentionally added) catalysts used in the present invention include dehydrated carriers, alumoxanes and one or more metallocenes. The catalyst is free-flowing and has a particle size of about 1 μm to about Particulate form comprising dry powder particles of 250 μm, preferably from about 10 μm to about 150 μm. Catalysts comprising only one transition metal in metallocene form have at least about 200 kg polymer / g transition metal activity. The amount of loading aluminoxane and metallocene on the carrier is such that the amount of aluminum provided by the aluminoxane on the carrier (based on the element) is 1% to 40% by weight, preferably 5% to 30% by weight and Most preferably from 5% to 15% by weight. The optimum MAO loading is 3 mmole to 15 mmoles per gram of silica carrier; When the silica carrier is overloaded with MAO, the catalytic activity is lowered and the catalyst particles aggregate to create a problem of catalyst transfer,

The amount of metallocene on the carrier is from 0.001% to 10% by weight, preferably from 0.05% to 1.0% and most preferably from 0.05% to 0.5% by weight, based on the transition metal element. Therefore, the ratio of Al: Zr (based on the elements) in the catalyst may be 25 to 10,000, usually 50 to 1000, but about 75 to 350 is preferred, and 100 to 200 is most preferred.

In order to form the catalyst of the present invention, all catalyst components can be dissolved together with alumoxane and impregnated into the carrier. Catalyst preparation is carried out in an anhydrous state without oxygen. In one specific process, the carrier material is absorbed into alumoxane, preferably methylalumoxane, in the process described below. The class of alumoxanes comprises oligomeric linear and / or cyclic alkalilumoxanes of the general formula:

R- (Al (R) -O) n-AlR ₂ (for oligomeric linear alumoxane); And (-Al (R) -O-) m (for oligocyclic alumoxanes)

(Wherein n is 1 to 40, preferably 10 to 20, m is 3 to 40, preferably 3 to 20, and R is a C ₁ -C ₈ alkyl group, preferably methyl)

MAO is a mixture of oligomers with a very wide molecular weight distribution, usually having an average molecular weight of about 1200. MAO is usually stored in toluene solution.

The volume of the solution comprising alumoxane and a solvent for alumoxane may vary depending on the catalyst to be prepared. In a preferred embodiment of incorporating alumoxane into the carrier for catalyst synthesis, one of the factors controlling the incorporation of alumoxane into the carrier material is the pore volume of the silica. In a preferred embodiment, the method of impregnating the carrier material is to inject the alumoxane solution without forming a slurry of carrier material such as silica in the alumoxane solution. This is carried out under stirring.

The volume of the alumoxane solution should be sufficient to fill the pores of the carrier material without forming a slurry whose solution volume exceeds the pore volume of silica; Thus, preferably the maximum volume of the alumoxane solution is equal to but does not exceed the total pore volume of the carrier material sample. The maximum volume of alumoxane solution ensures that no slurry of silica is produced in the solvent in this step. For example, if the pore volume of the carrier material is 1.65 cc / g, the volume of alumoxane will be no greater than 1.65 cc per g of carrier material. Thus, the maximum volume of solution (metallocene and alumoxane) will be equal to the total pore volume of the carrier, for example silica (unit of pore volume is for example cc / g) x the total weight of the carrier used. As a result, the impregnated carrier material will appear dry immediately after impregnation, although the pores of the carrier may be filled with solvent in particular. A preferred solvent for aluminoxanes, for example methylaluminoxane, is toluene. The impregnation is advantageously carried out in a single solvent system.

The solvent may be removed from the alumoxane impregnated pores of the carrier material by washing with an inert gas such as nitrogen under heating and / or under vacuum or while heating. If elevated temperatures are used, the temperature conditions in this step are adjusted to reduce (if not intending to remove) aggregation of impregnated carrier particles and / or crosslinking of alumoxane.

In this step, the solvent may be removed by evaporation performed at relatively low elevated temperatures of greater than about 40 ° C. and less than about 60 ° C. to avoid agglomeration of catalyst particles and crosslinking of alumoxane.

Drying is preferably carried out at 45 ° C. or lower for 5 to 7 hours. The solvent can be removed by evaporation at a temperature that is relatively higher than the temperature specified in the range above 40 ° C. and below about 60 ° C., but in this case it is very much accompanied by a decrease in catalyst activity to avoid aggregation of the catalyst particles and crosslinking of alumoxane. Short heating time is required. Thus, the active catalyst is prepared at an evaporation temperature of 110 ° C. (within 10 seconds), while drying can be performed at 45 ° C. for 24 hours.

In a preferred embodiment, metallocene is added to the alumoxane solution before the carrier is impregnated with the solution. In other words, the maximum volume of alumoxane solution containing metallocene is the total pore volume of the carrier material sample. The molar ratio of aluminum represented by Al to metallocene metal represented by M (eg, Zr), provided by aluminoxane, is from 50 to 500, preferably from 75 to 300 and most preferably from 100 to 200 to be. Another advantage of the present invention is that it is possible to directly adjust this Al: Zr ratio. In a preferred embodiment, the alumoxane and metallocene compound are mixed together for 0.1 to 6.0 hours at ambient temperature before use in the infusion step. Solvents for metallocenes and alumoxanes may be suitable solvents such as aromatic hydrocarbons, halogenated aromatic hydrocarbons, ethers, cyclic ethers or esters; Toluene is preferred.

The general formula of the metallocene compound is Cp _m MA _n B _p , where Cp is a substituted or unsubstituted cyclopentadienyl group, M is zirconium or hafnium, and A and B are halogen atoms, hydrogen or alkyl groups It belongs to the group that contains. In the general formula of the metallocene compound, the preferred transition metal atom M is zirconium. In the general formula of the metallocene compound, the Cp group is an unsubstituted, monosubstituted or polysubstituted cyclopentadienyl group.

Substituents for cyclopentadienyl groups are preferably straight or branched C ₁ -C ₆ alkyl groups, and cyclopentadienyl groups are also such as indenyl, tetrahydroindenyl, fluorenyl or partially hydrogenated fluorenyl groups. It may be part of a bicyclic or tricyclic moiety as well as part of a substituted bicyclic or tricyclic moiety. In the general formula of the metallocene compound, when m is 2, the cyclopentadienyl group is -CH ₂ , -CH ₂ -CH ₂ -,-CR'R "-and -CR'R"-CR'R"- (wherein, R 'and R "are short-chain alkyl group or _{hydrogen), -Si (CH 3) 2} -, Si (CH 3) 2 -CH 2 -CH 2 -Si (CH 3) 2 - , such as polymethylene or di Crosslinking can be formed by alkylsilane groups and similar crosslinking groups. In the general formula of the metallocene compound, when the substituents A and B are halogen atoms, they belong to the fluorine, chlorine, bromine and iodine groups. In the general formula of the metallocene compound, when substituents A and B are alkyl groups, they are straight chains such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, n-hexyl floating n-octyl Or a branched C ₁ -C ₈ alkyl group.

Suitable metallocene compounds include bis (n-butyl-cyclopentadienyl) metal dihalide, bis (n-butyl-cyclopentadienyl) metal hydridohalide, bis (n-butyl-cyclopentadienyl) metal Monoalkyl monohalides, bis (n-butyl-cyclopentadienyl) metal dialkyl and bis (indenyl) metal dihalide, wherein the metal is zirconium or hafnium, the halide group is preferably chlorine, the alkyl group C ₁ -C ₆ alkyl. Non-limiting examples of metallocenes include bis (n-butylcyclopentadienyl) zirconium dichloride, bis (n-butylcyclopentadienyl) hafnium dichloride, bis (n-butylcyclopentadienyl) zirconium dimethyl, Bis (n-butylcyclopentadienyl) hafnium dimethyl, bis (n-butylcyclopentadienyl) zirconium hydridochloride, bis (n-butylcyclopentadienyl) hafnium hydridochloride, bis (1,3-di Methylcyclopentadienyl) zirconium dichloride, bis (pentamenylcyclopentadienyl) zirconium dichloride, bis (pentamethylcyclopentadienyl) hafnium dichloride, bis (iso-butylcyclopentadienyl) zirconium dichloride, Cyclopentadienyl-zirconium trichloride, bis (indenyl) zirconium dichloride, bis (4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride and ethylene- [bis (4,5,6 , 7- Inde trad dihydro-1-indenyl)] zirconium dichloride a. Metallocene compounds used in embodiments of the art can be used in crystalline solids, solutions in aromatic hydrocarbons or in supported forms.

The carrier material is a particulate porous solid and inorganic materials such as oxides of silicon and / or aluminum are preferred. In the most preferred embodiment, the carrier is silica in the form of spherical particles obtainable by a spray-drying process. The carrier material is used in the form of dry powder having an average particle size of about 1 μm to about 500 μm, preferably about 1 μm to about 250 μm, most preferably about 10 μm to about 150 μm. If necessary, the final catalyst containing the carrier material is fractionated to remove large catalyst particles. Then removal of the catalyst particles having a particle size larger than 500 μm is carried out; Preferably, removal of particles larger than 250 μm in particle size and most preferably removal of particles larger than 150 μm in particle size is performed. Body fractionation of the material is preferably performed after impregnating the carrier using metallocene and aluminoxane. This is highly preferred in embodiments of the present invention wherein the catalyst contains only one transition metal in the form of medallocene, forms a narrow molecular weight LLDPE, and reduces the gel and reactor hot portion in the final polyolefin product. Used to reduce or eliminate.

The surface area of the carrier is about 3 m 2 / g or more, preferably 5 m 2 / g to 1200 m 2 / g, most preferably about 50 m 2 / g or more and about 35O 2 m 2 / g or less. The pore volume of the carrier is from 0.1 m 3 / g to 5 cm 3 / g, preferably from 0.1 m 3 / g to 3.5 cm 3 / g. The carrier material must be dry, ie free of absorbed water.

The carrier is preferably silica containing a [OH] group. The hydroxyl group of the silica may be from 0 mmole / g to 2.5 mmole / g silica, but preferably from 0.5 mmole to 2.5 mmole per gram as evident below. This range is suitable for lower drying, dehydration and / or firing temperatures.

Silica hydroxyl groups (silanol and silica hydroxyl used herein interchangeably) can be detected by IR spectrophotometry. Quantitative determination of hydroxyl concentration relative to silica is performed by contacting the silica sample with methyl magnesium iodide and measuring the methane emissions (by pressure measurement).

Dehydration of the silica material may be carried out by heating at about 100 ° C to about 600 ° C, preferably at about 150 ° C to about 300 ° C, most preferably at about 250 ° C.

Silica dehydrated at 600 ° C. (for about 16 hours) has a silica hydroxyl concentration of about 0.7 mmole per gram of silica. Dehydrated silica at 800 ° C. will have 0.5 mmole of silica hydroxy per gram of silica. Silica of the most preferred embodiment is amorphous silica (surface area = 300 m 2 / g; pore volume 1.65 cm 3 / g) with a large surface area. egg. Commercially available under the trade names Davidson 952 or Davidson 955 from the Davidson Chemical Division of Grace and Company. At the time of purchase, the silica is not dehydrated and must be dehydrated before use.

The effect of silica hydroxyl groups on catalyst activity and productivity will be reflected in the examples below. Catalytic synthesis of the present invention exhibiting maximum activity means that the silica contains hydroxyl groups for contact with a solution containing aluminoxane and metallocene as described below. The reaction of the hydroxyl groups of silica with scavengers such as trialkylaluminum compounds, for example trimethylaluminum (TMA), is made in comparison with a catalyst formed of silica bearing hydroxyl groups that do not react with these scavengers. It was determined to reduce the activity of the catalyzed catalyst. Silicas with more hydroxyl groups produce catalysts that are more active than silicas with fewer hydroxyl groups; This can be achieved by treating silica with trimethylaluminum prior to catalyst synthesis and reacting with silanol or silica hydroxy groups (using a suitable molar amount of TMA, as indicated by IR, the hydroxyl concentration is reduced to zero). It can be seen that the catalyst is produced with the productivity of kg (polymer) / g transition metal. However, the activity is good activity, and catalysts exhibiting this activity are useful in the process of the present invention. In comparison, a catalyst having a hydroxyl group content of 1.8 mmole / g silica shows a productivity of about 100 kg (polymer) / g transition metal. The amount of hydroxyl groups represented by mmole / g silica can be influenced by the dehydration temperature used to control the silica. In particular, a dehydration temperature of about 600 ° C. reduces the amount of reactive hydroxyl groups that may be in contact with a solution of aluminoxane and metallocene. In comparison, a dehydration temperature of about 250 ° C. increases the amount of reactive hydroxyl groups that can be in contact with a solution of aluminoxane and metallocene compared to silica heat treated at 600 ° C. for dehydration purposes. Thus, it was confirmed that the catalyst prepared by treating silica at a dehydration temperature of 250 ° C. has higher activity than the catalyst prepared by silica treated at a drying temperature of 600 ° C. Thus, the preferred number of months and / or calcination temperatures is less than 300 ° C, with about 250 ° C being preferred.

Thus, the silica used in the embodiments of the present invention has a silanol (OH) concentration of greater than 0,7 mmole OH per gram of silica; It will preferably contain from 0.7 mmole to 2.5 mmole OH per gram of silica. In a preferred embodiment, the concentration is 1.6 mmoles / g to 1.9 mmoles / g silica.

[Polymerization and Copolymerization Reaction Products]

Both high bulk density, low molecular weight (hexane) extracts, granular low density (0.91 g / cc to 0.939 g / cc) and high density (0.94 g / cc to 0.965 g / cc) products are slurries without contamination. It can be prepared in a reactor. The resin produced is high molecular weight, narrow molecular weight distribution range and uniform branch distribution. The catalyst ash contains a small amount of Zr and Al (derived from the catalyst), such as less than 1 ppm of Zr and 40 ppm of Al (derived from the catalyst), producing a product with a long catalyst life and a high bulk density The high activity of the catalysts of the present invention is an important factor in the unexpected efficiency of these catalysts in the catalytic polymerization and copolymerization of olefins.

More specifically, the copolymer product comprises 0.1 ppm to 2 ppm Zr. The average particle size of the product is 0.015 to 0.035 inches (0.38 cm to 0.89 cm) and the fixed bulk density is 15 lb / ft ³ to 36 1 b / ft ³ (240 kg / m ³ to 580 kg / m 3). Particles of the product are free-flowing. Low density copolymers with narrow molecular weight distribution have been prepared having a melt index (MI) of 1 or less and up to 0.01. The low density product of the present invention exhibits Ml which can range from 0.01 to 5, preferably 0,5 to 4, most preferably 0.8 to 2.0.

Thus, the product in the slurry reactor is characterized by a MI of less than 10, preferably less than 5, most preferably less than 3. The low density products of the present invention have a melt flow ratio (MFR) of less than 30, generally 15 to 25, preferably 16 to 22; Products with MFR from 16 to 22 are prepared; Wherein MFR is I ₂₁ / l ₂ ratio (where, I ₂₁ is the value measured at 190 ° C. according to ASTM D-1238, condition F, and I ₂ is the value measured according to ASTMD-1238, condition E). Differential scanning calorimeter data suggest that the heat seal temperature of the polymerization reaction product is very low. When made into a film, the film of the copolymer exhibits a stable tear strength as measured by ASTM D-1922. In addition, the LLDPE of the present invention has a Dart Drop Impact value of more than 800, as measured by ASTM D-1709. The product of the catalysis using the catalyst of the present invention is almost gel free. The film has a low haze value as measured by ASTM D-1003.

EXAMPLE

CHEME Manufacture:

Example 1 Influence of TMA Absence on S988

5 g of PQ 988 silica dehydrated at 600 ° C. was treated with 11.2 cc of a solution prepared by dissolving (n-butylCp) .2ZrCl 2 and MAO in toluene. Gas evolution was observed. Schering's MAO solution had an Al content of 13.2% by weight. Al / Zr ratio was 200: 1. The catalyst was dried at 38 ° C. to 42 ° C. for 2 hours under a N ₂ flow. The catalyst containing 14.3 wt% Al and 0.18 wt% Zr was named 1A.

Example 2 Effect of 0.75 mmol TMA / g on 988 Silica

5 g of PQ 988 silica dehydrated at 600 ° C. was slurried in 25 ml of heptane and treated with 2.9 ml of a TMA solution (14 wt% in heptane) corresponding to 0.75 mmol TMA / g silica. Gas evolution was observed during TMA treatment. The slurry was dried at 80 ° C. to 90 ° C. until free-flowing powder formed. TMA treated silica was treated with 11.1 ml of the MAO / Zr solution described in Example 1. At this point no gas evolution was observed. The catalyst was dried for 2 hours at 42 ° C. to 44 ° C. under N ₂ flow and named 2B. The catalyst contained 11,9 wt% Al and 0.13 wt% Zr.

Example 3 Effect of 1.5 nnnol TMA / g on 988 Silica

5 g of PQ 988 silica dehydrated at 600 ° C. were slurried in 25 ml of heptane and treated with 6 ml of a TMA solution (14 wt% heptane) corresponding to 1.5 mmol TMA / g silica. Gas evolution was observed during TMA treatment. The slurry was dried at 80 ° C. to 90 ° C. until free-flowing powder formed. TMA treated silica was treated with 11.1 ml of the MAO / Zr solution described in Example 1. At this point no gas evolution was observed. The catalyst was dried at 42 ° C.-44 ° C. for 2 hours under N ₂ flow and named 3A. The catalyst contained 11.1 wt% Al and 0.12 wt% Zr.

Example 4-6

Catalysts corresponding to the three examples were prepared using Davidson 955-600 silica as a support. They were named 4, 5 and 6. They contained 15.0, 14.6 and 14.5 weight percent Al and 0.18, 0.18 and 0.17 weight percent Zr, respectively.

Slurry Polymerization for LLDPE

Example 7

The polymerization reaction is carried out at 70 ° C. using 1 L of heptane of polymerization quality in a 2 L slurry reactor. Hexene-1 (100 cc) and triisobutyl aluminum (TIBA, 2 cc of solution prepared by dissolving 25% by weight in heptane) were added to the reactor. At the reaction temperature, ethylene (120 psi [0.83 MPa]) was added to saturate the liquid. About 80 mg of the catalyst of Example 1 was added to the reactor and the polymerization reaction was carried out for 1 hour. 83 g of a granular product having an I ₂ of 1.00, an MFR of 17.4, a density of 0.914 g / cc and a productivity of 959 g PE / g catalyst / hour / 1OO psi C ₂ were obtained.

The product was easily removed from the reactor and little evidence of contamination of the reactor was found.

Example 8-12

Table 1 illustrates the polymerization reaction results similar to those using the catalysts of Examples 1-6. The conditions were the same as those in Example 7.

TABLE 1

Productivity was expressed as g PE / g catalyst / hour / 100 psi C2 =, density was 0.914 to 0.918 g / cc.

[Slurry LLDPE Form]

Non-polluting operation of laboratory slurry reactors involves the formation of granular PE products. Two basic particle forms can be formed in the reactor. Solid, transparent, spherical particles predominantly do not pre-treat the TMA (catalysts of Examples 1 and 4) and have a small amount of white amorphous analogous polymer to which some particles bind together. As the contamination of the reactor increases with the TMA pretreated catalyst, the relative amount of white rubbery material increases.

Under these conditions, PQ 988 silica produces less white polymerizable binder than Davidson 955 silica, which is desirable for the preparation of non-contaminating granular LLDPE. However, acceptable catalysts can be prepared using 955 silica, as demonstrated in the examples below.

Example 13

A catalyst similar to the catalyst of Example 1 was prepared on 955-600 silica. No TMA was used to pretreat the silica. The Al / Zr ratio was 200: 1. The MAO loading was 7 mmol Al / g silica and Zr was 0.035 mmol / g silica. In this case MAO was purchased from ethyl corporation, which contained somewhat less free TMA than the Schering MAO used. Under the polymerization conditions of Example 7, 128 g of a granular polymer having a MI of 1.4, an MFR of 20, a productivity of 1100 g / g catalyst / hour / 100 psi C2, and a density of 0.916 was obtained.

Example 14 Metallocene Catalyst Supported on Sulrika Phase Treated at Different Dehydration Temperatures

Four catalysts were prepared using the same composition and the same method as Example 13 except for silica having a dehydration temperature of 20 ° C. (vacuum), 110 ° C. and 300 ° C., respectively. These catalysts were tested using a procedure similar to Example 7 in a slurry reactor. The results are summarized in Table 2.

TABLE 2

In all cases, the resin form was good and there was no reactor contamination.

Example 15

The following examples illustrate that other metallocene compounds may be used in the preparation of the catalyst, but differ in the catalyst productivity and resin density, FI and MFR. The catalyst was prepared in a similar manner to Example 13 except that different metallocene complexes were used. Silica dehydration temperature and polymerization reaction results are listed in Table 3.

TABLE 3

Cp ^* Zr = bis (pentamethylcyclopentadienyl) zirconium dichloride

IndZr = bis (indenyl) zirconium dichloride

CpZr = bis (cyclopentadienyl) zirconium dichloride

MeCpZr = bis (methylcyclopentadienyl) zirconium dichloride

CpTi = bis (cyclopentadienyl) titanium dichloride

CpZr = bis (pentamethylcyclopentadienyl) titanium dichloride

In all cases, the resin form was good and there was no reactor contamination.

Example 16

The following examples illustrate the high bulk density, average particle size and high yield per unit reactor or solution volume of the granular product. Very high catalytic efficiency regarding the use of both medalosene complexes and the use of methylalumoxane is illustrated in the examples below.

The catalyst was prepared using standard methods as described in Example 13. Silica dehydration temperature, MAO loading, metallocene loading and drying time were varied to indicate the range of these parameters.

The polymerization reaction was carried out in a semi-batch reactor under a temperature of 70 ° C. and a pressure of 125 psig (0,96 MPa). 1 liter of heptane and 10 cc of hexene were measured in the reactor. Ethylene at a pressure of 125 psig (0.96 MPa) was introduced into the reactor before a small amount of catalyst sample was injected into the reactor. Table 4 and Table 5 show the results.

TABLE 4

TABLE 5

Claims (18)

(a) dispersing a catalyst comprising a support, a transition metal and aluminum in an alkane solvent under substantially anhydrous to form a slurry in the reaction vessel; (b) maintaining the slurry at an absolute pressure of less than 1,000 psi (6.9 MPa) and at a temperature of 20 ° C. to 100 ° C .; (c) introducing into the reaction vessel ethylene and a C3-C10 alpha olefin having a partial pressure of 20 psi to 1,000 psi (0.14 MPa to 6.9 MPa): and (d) a bulk density of 15 lb./ft ³ to 36 lb./ft ³ (240 kg / m ³ to 580 kg / m 3), specific gravity less than 0.98 g / cc, and MFR (melt flow ratio) of about 30 A method for producing granular resin, comprising recovering less than granular resin, The granule according to claim 1, wherein in step (d), ethylene and alpha olefin are copolymerized to form a granular resin which is almost insoluble in a solvent and has an average particle size of 300 µm to 800 µm. Method for producing a resin. The method for producing granular resin according to claim 1, wherein the specific gravity is less than 0.94. The method for producing granular resin according to claim 1, wherein the specific gravity is less than 0.93. The granular form according to claim 1, wherein the support is amorphous, porous, containing silica having a pore volume of 0.1 cc / g to 5 cc / g, and the silanol group concentration of the silica is less than 2.5 mmole per gram of silica. Method for producing a resin. 6. The preparation of granular resin according to claim 5, wherein the silica is in contact with a certain volume of the mixture comprising metallocene and aluminoxane, wherein the volume of the mixture is less than or equal to the total pore volume of the dehydrated silica. Way. The metallocene of claim 6, wherein the metallocene is of the general formula Cp _m MA _n B _p , wherein Cp is a substituted cyclopentadienyl group; m is 1 or 2; M is zirconium or hafnium; and A and B are each Selected from the group consisting of a halogen atom, a hydrogen atom and an alkyl group, m + n + p is the same as the valence of the metal M), wherein the alumoxane is represented by the following general formula (a) or (b); (a) R- (Al (R) -0) n-AlR ₂ (for oligomeric linear alumoxanes); (b) (-Al (R) -O-) _m (for oligomeric cyclic alumoxanes) (Wherein n is 1 to 40: m is 3 to 40; R is a C ₁ -C ₈ alkyl group); The method of producing a granular resin, characterized in that the contacted silica is an activated catalyst. The method of claim 1, wherein the catalyst is in the form of particles having a particle size of 1 μm to 500 μm. The process for producing granular resin according to claim 1, wherein the ratio of aluminum to transition metal in the catalyst is about 70 to about 350. The method of claim 1, wherein the amount of transition metal (based on an element) is from 0.1% to 10% by weight, and the amount of aluminum (based on an element) is 1% to 40% by weight; The Al: the ratio of the transition metal (based on the element) is 25 to 10000 method for producing a granular resin. The catalyst of claim 1 wherein the catalyst is bis (n-butylcyclopentadienyl) metal dihalide, bis (n-butylcyclopentadienyl) metal hydridohalide, bis (n-butylcyclopentadienyl) metal monoalkyl A metallocene selected from the group consisting of monohalide, bis (n-butylcyclopentadienyl) metal dialkyl, bis (tetrahydroindenyl) metal halide and bis (indenyl) metal dihalide The manufacturing method of granular resin made into. 12. The process of claim 11 wherein the catalyst is bis (iso-butylcyclopentadienyl) zirconium dichloride, bis (pentamethylcyclopentadienyl) zirconium dichloride, bis (tetrahydroindenyl) zirconium dichloride, bis (indenyl ) Zirconium dichloride, bis (1,3-dimethylcyclopentadienyl) zirconium dichloride, bis (methylcyclopentadienyl) zirconium dichloride, and bis (n-butylcyclopentadienyl) zirconium dichloride Method for producing a granular resin, characterized in that it comprises a metallocene selected from the group, The method of claim 1, wherein the concentration of the alpha olefin in the solvent is 0.1 wt% to 50 wt%. The method for producing granular resin according to claim 13, wherein the concentration of alpha olefin in the solvent is 0.1 wt% to 30 wt%. The process for producing granular resin according to claim 1, wherein the solvent is one or more alkanes containing 4 to 19 carbon atoms. The compound of claim 15 wherein the alkane is selected from the group consisting of isobutane, pentane, isomers of pentane, nucleic acids, isomers of hexane, heptanes, isomers of heptane, octane, isomers of octane, decane, dodecane and mixtures thereof. The manufacturing method of granular resin characterized by the above-mentioned. The method for producing granular resin according to claim 1, wherein the boiling point of the solvent is less than 180 ° C. The method of claim 1, wherein the pressure in step (b) is less than 600 psi (4.1 MPa).