NO155199B - MAILED OLEPHINE POLYMERIZATION AND COPOLYMERIZATION CATALYST. - Google Patents

Description

The present invention relates to a supported polymerization and copolymerization catalyst.

The catalyst according to the invention is suitable for polymerization

and copolymerization of ethylene and other 1-olefins, especially of 2-8 carbon atoms and copolymerization of these with 1-olefins of 2-20 carbon atoms, such as propylene, butene and hexene. It is well suited for economical particulate form and gas phase polymerization products. The active component in the catalyst is applied to particles of an organic polymer, and the selection of this affects the particle size from the melt index and the molecular weight distribution in the product polymer. Furthermore, the density in the product mass is relatively high and can be controlled by choosing a carrier for the polymer.

An improved catalyst for the polymerization and copolymerization of olefins is prepared by combining three reactive materials in the presence of particles of an organic polymeric carrier. A reaction product of the three reactive materials is formed on and attached to the support, and is activated by contact with an active amount of an alkylaluminum compound such as trialkylaluminum.

The reaction product with carrier is believed to be a complex of those

three reactive materials and comprises a major part of the highly active form of titanium oxide over a wide range of molar ratios of reactants. Due to the higher activity of the complex, it is not necessary to remove non-reactive titanium from the catalyst, but one can wash the catalyst if desired.

Because of its high activity, the catalyst is well suited for use in polymerization processes using particles where supported catalyst, the cocatalyst and the olefin monomer are brought into contact in a suitable solvent or a gas phase process where no solvent is required. According to the present invention there is provided a supported olefin polymerization and copolymerization catalyst which is active in the presence of an organometallic cocatalyst, prepared by mixing reactive materials including a lower alkyl aluminum halide, a dialkyl magnesium compound and ^ eri* reducible titanium compound of formula Ti(OR) n X4 . -n,

wherein R is an alkyl group, X is a halogen atom and n is an integer between 0 and 4, inclusive, in the presence of a solvent and a particulate organic polymer to form a reaction product supported on said particles, and evaporating the solvent at a temperature which is lower than the organic polymer's softening temperature, characterized in that the organic polymer consists essentially of high-density polyethylene, to which between 0.5 and 30% by weight of an organic carboxylic acid or carboxylic anhydride is bound.

The titanium compound can thus be a titanium alkoxide or titanium alkoxide halide. The alkyl aluminum halide is selected from the group comprising dialkyl aluminum halides, alkyl aluminum sesquihalides and alkyl aluminum dihalides, with ethylene aluminum sesquichloride being preferred. A preferred titanium-tan compound is titanium tetraisopropoxide.

Preferred dialkylmagnesium compounds are dibutylmagnesium, di-n-hexylmagnesium and butylethylmagnesium, where these can be complexed with an alkylaluminum compound, such as tri-alkylaluminum, to increase the solubility of the magnesium compound and/or reduce the viscosity of the magnesium compound solution.

Preparation of the carrier.

The reaction product catalyst according to the invention is formed and attached to the surface of the polymeric carrier particles to a degree that depends on the physical and chemical nature of the carrier material. In a similar way, the characteristic properties are determined in the product polymer that grows from catalyst over-

the surface of the characteristic properties in the carrier.

In order for a polymerization reaction to occur by polymer growth on a support, it is obviously necessary that the support particles remain intact (ie that they do not melt, dissolve, or otherwise degrade) under the reaction conditions. The polymerization in particulate form can be carried out at temperatures up to 110°C in a hydrocarbon solvent such as isobutane, e.g. Therefore, a polymeric support which melts or otherwise decomposes at temperatures up to 110°C or which dissolves in isobutane or equivalent solvent at these temperatures is not a suitable support for the catalyst.

Furthermore, the carrier material must be largely chemically inert with respect to the catalyst that is formed on it.

It has been shown that very high concentrations of polar groups

in the support material results in reaction of the reactants that form the catalyst with the support, and this should therefore be avoided. However, a relatively small amount of polar groups in the carrier is useful in that it promotes association between the catalyst and the carrier and an even distribution of the catalyst on this.

Such attachment can also be promoted by mixing up to 20% of an amorphous or only slightly crystalline hydrocarbon polymer into a largely crystalline polymeric carrier material.

It has been demonstrated that the production of carrier particles by painting the carrier material results in a carrier material surface that promotes attachment of the catalyst to the carrier material. The techniques known as cryogenic painting are particularly preferred. The carrier particles can vary in diameter from 20 µm to up to 5 mm.

For use in automatic catalyst feed valves commonly used in polymerization plants that polymerize in particulate form, small particles are usually preferred, although alternative methods of feeding can be used for larger carrier particles. In addition, normal feed valves work most effectively with materials that have flow properties that correspond to those usually used in silicon dioxide catalysts. Re-trainable spherical carrier particles are particularly useful for use in such automatic valves. Furthermore, the flow property in the carrier is improved by the addition of small amounts, such as up to 10% by weight of fumed silica such as silica with the designation Cab-O-Sil.

Specific examples of suitable carrier materials are high density polyethylene and isotactic polypropylene. US Patent No. 3,873,643 provides an excellent example of a polymer containing low concentrations of polar groups suitable for use as a carrier in the present invention. The material in patent US 3,873,643 comprises high-density polyethylene grafted with organic anhydrides.

Catalyst-forming reactants.

The catalyst according to the invention comprises the reaction product of (1) an alkyl aluminum halide, (2) a dialkyl magnesium compound or complex, and (3) a titanium alkoxide or titanium alkoxide halide which is applied to an organic support as described above and which is used in the presence of an alkyl aluminum co-catalyst . The reaction with the three components can be carried out at or below room temperature in the presence of the carrier particles and is preferably carried out in a suitable solvent such as isobutane.

The alkylaluminum halide is selected from the group comprising dialkylaluminum halides, alkylaluminum sesquihalides and alkylaluminum dihalides. A preferred alkyl aluminum halide is ethyl aluminum sesquichloride.

The dialkylmagnesium compound, which may be present in the form of an alkylaluminium complex, is preferably dibutylmagnesium, di-n-hexylmagnesium or butylethylmagnesium.

The titanium compound is preferably titanium tetraisopropoxide.

Previously used catalysts using aluminum chloride or other chlorides tend to be corrosive and require special handling equipment. A washing step is also required to remove residual chloride from the catalyst. In the present invention, the alkylaluminum halide and the titanium alkoxide halide, if present, form complexes with the dialkylmagnesium compound almost completely independently of the respective molar ratios of these components over a wide range of the molar ratio, which eliminates residues from the catalyst surface and also results in a reduction in lost titanium and magnesium. No special equipment is therefore required to treat the catalyst according to the invention,

and a washing step is not necessary either.

Each of these three reactive components can be present in hydrocarbon solution and, when reacted in the presence of the polymeric carrier particles of the type described, react so as to deposit an insoluble reaction product on the surface of the particles. The mixing of the reactive materials is carried out preferably at or below room temperature. After the watering is complete, the preparation is dried, preferably by heating above room temperature, but the temperature is less than the softening temperature of the polymeric carrier. The drying step promotes the formation of particles so that unevenly shaped pieces are not obtained in a polymerization reaction in a slurry and the reactor problem is reduced.

It is usually best to heat the catalyst under inert

gas at a temperature of 90-100°C, for from % to 10 hours, or until dry.

The amount of titanium compound is chosen so that from 0.1 to 10% by weight of titanium is obtained in the reaction product. The respective molar ratios between alkylaluminum halide, dialkylmagnesium and titanium alkoxide can be adjusted so that optimal reactivity is obtained or so that the polymer properties are modified. In a similar way, the molar ratio between the alkyl aluminum activator and phase catalyst can be adjusted. Hydrogen can be added to the polymerization reaction system to control the molecular weight of the product in a manner known per se.

Reaction conditions.

The reaction system in particle form is characterized by the addition of monomer to a stirred catalyst solution slurry.

The solution is usually isobutane and the reaction is best carried out in a closed vessel to promote pressure and temperature controls. The pressure is regulated by adding nitrogen and/or hydrogen to the vessel. Addition of the latter is useful for regulating the molecular weight in the product polymer as described in the following examples.

Polymerization in particulate form of ethylene with the catalyst according to the invention is best carried out at 105 - 110°C at a pressure of between 35 and 40 atmospheres. In gas phase polymerization, the temperature can vary from less than 85°C to 100°C with pressure as low as approx. 20 atmospheres. Copolymers can be produced by each process by adding propylene, butene-1, hexene-1 and corresponding alpha-olefins to the reactor. The production of copolymers with a relatively low density is preferably carried out at a relatively low temperature.

Example 1

Balls of high-density polyethylene with 1.33% by weight X-methylbicyclo/2,2,1/hept-5-ene-2,3-dicarboxylic acid anhydride attached to the pole, as described in US patent no. 3,873,643 and referred to here as XMNA- grafting, was ground into particles of approx. 1 mm in diameter.

10 grams of XMNA particles were added to a flask where the air was removed with a ^ supply. 20 ml each of cyclohexane and heptane solution of ethyl aluminum sesquichloride (7.7 mmol Et^

A12C13) was added with vigorous stirring.

10 ml of a heptane solution of dibutylmagnesium/triethylaluminum complex (9.1 mmol magnesium and 1.5 mmol triethylaluminum) was quickly added to the flask with stirring. 2.0 moles (6.64 mmol) of pure titanium tetraisopropoxide was added to the resulting slurry, and the color of the mixture became very dark. The catalyst was dried and heat-aged by heating to 90°C for 30 minutes while maintaining the N2~ supply. The remaining solid material was then tested as a supported ethylene polymerization catalyst. In the first polymerization test, 0.2230 g of the solid material was added to a closed polymerization vessel under a feed. 500 ml of isobutane was forced into the vessel and ethylene was added to maintain a total pressure of 38.5 atmospheres. The vessel was maintained at 105°C during the reaction. In 25 minutes, 6 grams of polystyrene were produced with a reactivity per hour with respect to solid catalyst of 65 g/g.

In another polymerization test, the procedure was identical except that 0.0958 g of the catalyst and 0.3 mL (0.28 mmol) of triisobutylaluminum (TIBAL) solution were added to the polymerization ion vessel. In this case, the reactivity was 910 g/g/h with respect to solid catalyst, 580 g/g/h with respect to total catalyst weight, including triisobutylaluminum, and 134,000 g/g/h with respect to titanium, clearly showing the favorable effect of using a triisobutylaluminum cocatalyst. The solid catalyst is calculated to be 1.17 wt% titanium on a solvent-free basis with a triisobutylaluminum to titanium molar ratio of 12/1.

Example 2

A solid catalyst compound was prepared according to the procedure described in Example 1, except 20 grams of XMNA was used and cyclohexane was not added. An ethylene and polymerization test was conducted at 105°C and 38.5 atmospheres using 0.0838 g of solid catalyst and a 6/1 mole ratio of TIBAL to titanium. The catalyst reactivity per hour was 920 g/g and the timer activity based on titanium was 105,000 g/g. The polyethylene product was preferably in the form of particles with a diameter of 1 to 2 cm. along with a smaller amount of fragments caused by the reactor stirrer. The bulk density of the product was as desirably high as 0.30 g/cm 3 and no product particles adhered to the reactor wall.

Example 3

A quantity of XMNA grafting was ground to approx. 30 mesh in a Wiley-type laboratory mill. 10 grams of the resulting powder was then combined with a solid catalyst in the procedure from Example 1. 0.1656 g of solid catalyst was used in an ethylene polymerization test with 1.0 ml (0.92 mmol) of TIBAL solution. The Al/Ti molar ratio was 22.8/1. The polymerization reaction was carried out at 105°C and 38.5 atmospheres.

In this sample, the catalyst reactivity per hour 400 g/g and the titanium reactivity was 77,200 g/g/h. The polyethylene product was in the form of particles with a diameter of 3-5 mm and none adhered to the reactor walls. With regard to Example 2, it is obvious that the reduction in the carrier size causes a reaction in the particle size in the product. The mass density of the product was again 0.3 g/cm 3.

Example 4

The support used in this example was XMNA graft which was ground by a cryogenic technique and sieved. Only particles passing through a 140 mesh sieve were used as catalyst. 100 g of XMNA particles were added to a bottle which had been filled with nitrogen as in Example 1. 10 ml of ethylaluminum sesquichloride solution and 5 ml of dibutylmagnesium/triethylaluminum complex solution from Example 1 were added rapidly with stirring, followed by the addition of 1.0 ml titanium tetraisopropoxide for a titanium content of 1.17% by weight on a solvent-free basis. The catalyst was dried as in Example 1.

0.0905 g of solid catalyst was used in an ethylene polymerization test under conditions corresponding to those of Example 1, except that the molar ratio of TIBAL to titanium was 26/1. The total catalyst reactivity is shown to be 860 g/g/h with a titanium reactivity of 179,000 g/g/h.

Example 5

A further polymerization test was made with the catalyst and reactants from Example 1, with a weight of solid catalyst of 0.0352 g and with a molar ratio of TIBAL to titanium of 25/1. The test was carried out at 105°C and 38.5 atmospheres.

The total catalyst reactivity was 1160 g/g/h, and the titanium reactivity was 260,000 g/g/h. The average particle size in the product was less than approx. 1 mm, and the mass density again 0.3 g/cm, which gives a further illustration of the effect of the particle size in the carrier material on the particle size in the product (see examples 2 and 3).

Examples 6-9

A supported catalyst was cryogenically prepared

ground XMNA grafting as described in Example 4. A series of four polymerization tests were carried out with this catalyst using a molar ratio of TIBAL to titanium of approx. 25/1 and a polymerization temperature of 107°C. After addition of solid catalyst and TIBAL, the isobutane was added to closed reaction vessels followed by ethylene. In three tests, the hydrogen was added to the reactor to increase the pressure to the extent indicated below followed by more ethylene to maintain a pressure of 38.5 atmospheres. The resulting reactivities are given below:

The number of vinyl groups in the product in example 7 turns out to be 0.40/2000 carbon atoms. This example illustrates that the melt index in the polyethylene product is directly related to the partial pressure of the hydrogen in the reaction system. Furthermore, it turns out that the vinyl unsaturation in the product is desirably low, which increases the resistance of the product polymer to oxidative degradation under the manufacturing conditions.

Examples 10-11

The solid catalyst used in these examples was the same as used in examples 6-9. The catalyst was a mixture of TIBAL and diethylzinc (DEZ). In each sample, 3.5 atmospheres partial pressure of the hydrogen was added to the reactor and the temperature and total pressure were maintained at 109°C and 38.5 atmospheres. The results are given below:

In Example 10, the weight of the solid catalyst was 0.0786 g

and 0.0498 g of catalyst was used in Example 11. The weight percent titanium was 1.17% in each case. These examples show that a mixture of alkylzinc and aluminum compounds can be used as a co-catalyst without this having any significant effect on the melt index in the polyethylene product.

Example 12

The carrier in this example was a polyolefin powder with an impact modifier commonly used for rotational molding.

The base fabric had a density of approx. 0.950 g/cm 3 and a melt index of 6.5. 10 g of carriers were mixed with ethyl aluminum sesquichloride, dibutyl magnesium/triethyl aluminum complex solution and titanium tetraisopropoxide as described in Example 4. After evaporation of solvent as described in Example 1, 0.0718 g of the resulting solid catalyst became 0.42 ml of TIBAL solution ( 0.92 mol in heptane) added to a polymerization vessel and the ethylene polymerization was carried out at 105°C and a total pressure of 38.5 atmospheres with a partial pressure for hydrogen of 3.5 atmospheres.

The reaction was continued for 90 minutes to give 160 g of polyethylene particles with a mass density of 0.33 g/cm 3 . The reactivity per hour was 185,600 g/g based on titanium and 1700 g/g based on total catalyst. The melt index was 4.8, and the high stress melt index was 101. A relatively low high stress to normal melt index ratio of 21 suggests a relatively narrow molecular weight distribution and a desirably low shear sensitivity in the product.

Example 13

A polymerization test was carried out with the solid catalyst from Example 12. A heptane solution of trihexyl aluminum was used instead of TIBAL as co-catalyst. The molar ratio between trihexylaluminum and titanium was 15.7/1. 3.5 atmospheres of hydrogen were added, followed by the addition of ethylene and the reaction was carried out at 105°C and a total pressure of 38.5 atmospheres. The reactivity per hour based on solid catalyst was 1200 g/g, and 99.300 g/g based on thiane. The melt index was 2.4, and the high load melt index was 79, and the ratio of the high load melt index to the melt index was 32.8. The mass density of the product was 0.26 g/cm 3.

Example 14

An ethylene polymerization test was performed with the solid catalyst from Example 12. The co-catalyst was diisobutylaluminum hydride in a molar ratio to titanium of 15.7/1. The polymerization conditions were identical to those used in example 9. The reactivity per hour based on solid catalyst was 1010 g/g and 84,500 .g/g based on titanium. The melt index was 3.7 and the high load melt index was 95.1, with a high to normal melt index ratio of 26. The bulk density of the product was 0.31 g/cm 3 .

Example 15

In this example, the carrier was a sample of cryogenically ground XMNA graft from Examples 6-9. 10 grams of XMNA inoculum was added to a bottle which had been supplied with N 2 and where the air had been removed, followed by the addition of 1.0 ml of titanium tetraisopropoxide. The mixture was then heated with a hot air apparatus under ^ supply, until the condensation of liquid on the upper part of the bottle ceased. 10 ml of heptane solution of ethyl aluminum sesquichloride (15.4 mmol Al) and 10 ml of heptane solution of dibutylmagnesium/aluminum complex (4.6 mmol B^Mg, and 0.75 mmol A19) were added. The solvent was evaporated by bath heating the catalyst at 100°C in 30 minutes under ^ feed leading to a solvent-free solid catalyst In an ethylene polymerization sample, 0.0457 g of solid catalyst was mixed with 0.2 7 ml (0.25 mmol) of TIBAL solution and 3.5 atmospheres of hydrogen was added as described above. The reaction was run for 150 minutes at 105°C and with a total pressure of 38.5 atmospheres. The yield per hour was 1050 g/g based on solid catalyst and 88,000 g/g based on titanium.

A sample of the polymer was pyrolyzed under standard conditions and left an ash of 60 dtm. This ash level is satisfactory for all commercial applications, and it has therefore been demonstrated that removal of catalyst residues is unnecessary. However, it has been proven that if the catalyst exceeds 30% by weight of the total of the reaction product and the polymeric carrier, unsatisfactory ash levels are obtained.

The melt index of the product was 2.7, the altitude stress melt index was 77, and the ratio between these was 28.4/1. The mass density was 0.31 g/cm 3 and the number of vinyl groups was 0.4 per 2 00 carbon atoms. This example illustrates that the order of mixing the three reagents with the carrier does not affect the catalytic activity. Other mixing ratios were also tried with similar results.

Example 16

In this example, a finely divided, high-density polyethylene with an average particle size of approx. 20 ym used as carrier material. A 10-gram amount of powder was added to a bottle that had been purged of air by stirring under a Nystrøm for 30 minutes at room temperature. Three catalyst formers were added to the bottle in the following order, while stirring with a magnetic bar was carried out:

(1) 10 ml of 25% ethyl aluminum sesquichloride in heptane,

(2) 10 mL of 10% dibutylmagnesium-triethylaluminum complex in heptane, and (3) a volume of pentane solution containing 0.1 mL of titanium tetraisopropoxide.

The contents of the bottle were therefore dried by heating for 30 minutes at 90°C, under a stream of dry N 2 . The calculated titanium concentration in this material was 0.10% by weight.

3.0 ml of 25% TIBAL solution per grams of solid catalyst were added and a polymerization test on ethylene production in particulate form was carried out at 105°C, and a total pressure of 38.5 atmospheres with 3.5 atmospheres of hydrogen. The total catalyst reactivity including TIBAL was 1244 g/g/h, and the reactivity based on titanium was 1,525,000 g/g/h. The melting index

in the particulate product was 0.20.

Example 17

A catalyst was prepared using the XMNA support from Example 4. 10 grams of powder was purged with N 2 and then combined with 7.5 mL of ethylaluminum sesquichloride solution (5.8 mmol in heptane), 6.5 mL of butylethylmagnesium

(3.85 mmol in heptane) and 0.6 ml of pentane solution containing 0.33 mmol of titanium tetraisopropoxide. The mixture was dried by heating under N, for 30 minutes at a temperature of 90°C. The calculated titanium content in the material was 0.11% by weight.

An ethylene polymerization test was carried out as described above at 105°C and a total pressure of 38.5 atmospheres with 5.25 atmospheres of hydrogen. The total catalyst reactivity was 1000 g/g/h, and the reactivity with respect to titanium was 1,170,000 g/g/h. The melt index in the polyethylene product was 1.14.

All parts and percentages are parts by weight.

Abbreviations used to identify chemical constituents and product properties include:

DEZ - diethylzinc

HLMI - high stress melt index

MI - melting index

TIBAL - triisobutylaluminium

XMNA - an X-methylbicyclo 2,2,1 hept-5-ene-2,3-dicarboxylic acid anhydride grafted polyethylene, as described in US Patent No. 3,873,643.

Claims (2)

1. Supported olefin polymerization and copolymerization catalyst active in the presence of an organometallic cocatalyst, prepared by mixing reactive materials including a lower alkyl aluminum halide, a dialkyl magnesium compound and a reducible titanium compound of formula Ti(OR) X^_ , where R is an alkyl group, X is a halogen atom and n is an integer between 0 and 4, inclusive, in the presence of a solvent and a particulate organic polymer to form a reaction product carried on said particles, and evaporating the solvent at a temperature lower than the organic polymer's softening temperature, characterized in that the organic polymer consists essentially of high-density polyethylene to which between 0.5 and 30% by weight of an organic carboxylic acid or carboxylic anhydride is bound. 2. Catalyst according to claim 1, characterized in that the organic polymer is an X-methylbicyclo/2,2,1/hept-5-ene-2,3-dicarboxylic acid anhydride-grafted polyethylene.