Heterogeneous ziegler-natta catalyst system and a process for olefin polymerization using the same

Abstract

The present disclosure provides a heterogeneous Ziegler-Natta catalyst system to be used in the preparation of ultra-high molecular weight polymers (UHMWP). The system includes at least one procatalyst, at least one co-catalyst, at least one hydrocarbon medium and at least one external donor, wherein the ratio of elemental magnesium to elemental titanium to halide, in the procatalyst, is 1:1.3:3.7; the ratio of elemental aluminum, present in the co-catalyst to elemental titanium, present in the procatalyst, ranges between 6:1 and 12:1; and the ratio of elemental silicon, present in the external donor to elemental titanium, present in the procatalyst, ranges between 1:10 and 10:1. The present disclosure also provides a process for preparation of UHMWPE using the heterogeneous Ziegler-Natta catalyst system of the present disclosure.

Claims

1. A heterogeneous Ziegler-Natta catalyst system for preparation of UHMWPE comprising: at least one procatalyst prepared from: at least one titanium halide; and at least one magnesium compound, wherein, the molar ratio of elemental magnesium to elemental titanium to halide in said procatalyst is 1:1.3:3.7; at least one co-catalyst comprising at least one organo-aluminum compound, wherein the molar ratio of elemental aluminum of said organo-aluminum compound to elemental titanium of said procatalyst ranges between 6:1 and 12:1; at least one hydrocarbon medium in an amount ranging between 0.4 and 0.61 per 0.1 mmole of the catalyst system; and at least one external donor comprising at least one organo-silane compound of Formula I, wherein the molar ratio of elemental silicon of said organo-silane compound to elemental titanium of said pro-catalyst is 4:1, ##STR00007## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 of said organo-silane compound is at least one selected from the group consisting of C.sub.1-C.sub.14 branched or straight chain alkyl, C.sub.1-C.sub.14 branched or straight chain alkyl oxy, substituted or unsubstituted aryl, substituted or unsubstituted aryl oxy, C.sub.4-C.sub.14 cyclic alkyl and C.sub.4-C.sub.14 cyclic alkyl oxy.

2. The catalyst system as claimed in claim 1, wherein said titanium halide is at least one selected from the group consisting of titanium chloride, titanium bromide, titanium iodide and titanium fluoride.

3. The catalyst system as claimed in claim 1, wherein said magnesium compound is at least one selected from the group consisting of magnesium halide, magnesium oxide, magnesium hydroxyl halides and magnesium salts of inorganic oxygen containing acids.

4. The catalyst system as claimed in claim 1, wherein said organo-aluminum compound is at least one selected from the group consisting of triethyl aluminum, tridecyaluminum, tri-n-butyl aluminum, tri-isopropyl aluminum, tri-isoprenyl aluminum, tri-isobutyl aluminum hydride, ethyl aluminumsesquichloride, diethyl aluminum chloride, di-isobutyl aluminum chloride, triphenyl aluminum, tri-n-octyl aluminium and tri-n-decyl aluminum.

5. The catalyst system as claimed in claim 1, wherein said hydrocarbon medium is at least one selected from the group consisting of pentane, hexane, cyclohexane, methyl cyclohexane, heptane, octane, nonane, decane, isopentane, varsol and isomers thereof.

6. The catalyst system as claimed in claim 1, wherein said organo-silane compound is at least one selected from the group consisting of tetraethoxysilane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, isobutylisopropyldimethoxysilane, n-propyltriethoxysilane, isobutyltriethoxysilane, phenyltriethoxysilane, diisopropyldimethoxysilane, diethyldimethoxysilane, diisobutyldimethoxysilane, aminopropyltriethoxysilane, diphenyldimethoxysilane and methyltrimethoxysilane.

7. A process for the preparation of a heterogeneous Ziegler-Natta catalyst system for preparation of UHMWPE; said process comprising the following steps: titanating at least one magnesium compound with at least one titanium halide, followed by allowing said titanium halide to bond with said magnesium compound, to obtain a mixture comprising at least one procatalyst; wherein the molar ratio of elemental magnesium to elemental titanium to halide is 1:1.3:3.7; separating and washing said mixture comprising the procatalyst to obtain a procatalyst; admixing said procatalyst and at least one organo-aluminum compound as a co-catalyst, in the presence of at least one hydrocarbon medium, to obtain an activated catalyst, wherein the molar ratio of elemental aluminum, present in said organo-aluminum compound to elemental titanium, present in said procatalyst, ranges between 6:1 and 12:1; and adding, in a controlled manner, at least one organo-silane compound of Formula 1 as an external donor to said activated catalyst, in the presence of at least one hydrocarbon medium, under inert conditions, at a temperature ranging between 25 C. and 30 C. and over a time period ranging between 2 and 10 minutes, to obtain a heterogeneous Ziegler-Natta catalyst system, wherein the molar ratio of elemental silicon, present in said organo-silane compound to elemental titanium, present in said procatalyst is 4:1, ##STR00008## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 of said organo-silane compound is at least one selected from the group consisting of C.sub.1-C.sub.14 branched or straight chain alkyl, C.sub.1-C.sub.14 branched or straight chain alkyl oxy, substituted or unsubstituted aryl, substituted or unsubstituted aryl oxy, C.sub.4-C.sub.14 cyclic alkyl and C.sub.4-C.sub.14 cyclic alkyl oxy.

8. The process as claimed in claim 7, wherein the hydrocarbon medium of steps (iii) and (iv) are same or different.

9. A process for the preparation of UHMWPE; said process comprising the following steps: titanating at least one magnesium compound with at least one titanium halide, followed by allowing said titanium halide to bond with said magnesium compound, to obtain a mixture comprising at least one procatalyst; wherein the molar ratio of elemental magnesium to elemental titanium to halide is 1:1.3:3.7; separating and washing said mixture comprising the procatalyst to obtain a procatalyst; admixing said procatalyst and at least one organo-aluminum compound as a co-catalyst, in the presence of at least one hydrocarbon medium, to obtain an activated catalyst, wherein the molar ratio of elemental aluminum, present in said organo-aluminum compound to elemental titanium, present in said procatalyst, ranges between 6:1 and 12:1; and adding, in a controlled manner, at least one organo-silane compound of Formula 1 as an external donor to said activated catalyst, in the presence of at least one hydrocarbon medium, under inert conditions, at a temperature ranging between 25 C. and 30 C. and over a time period ranging between 2 and 10 minutes, to obtain a heterogeneous Ziegler-Natta catalyst system, wherein the molar ratio of elemental silicon, present in said organo-silane compound to elemental titanium, present in said procatalyst is 4:1, and ##STR00009## incorporating said heterogeneous Ziegler-Natta catalyst system in ethylene monomer at a temperature ranging between 30 C. and 125 C., under ethylene pressure ranging between 2 bar and 10 bars, followed by agitation at a speed ranging between 300 and 700 revolutions per minute to obtain a polyolefin, wherein the ratio of said catalyst system and said monomer ranges between 1:20 and 1:220, wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 of said organo-silane compound is at least one selected from the group consisting of C.sub.1-C.sub.14 branched or straight chain alkyl, C.sub.1-C.sub.14 branched or straight chain alkyl oxy, substituted or unsubstituted aryl, substituted or unsubstituted aryl oxy, C.sub.4-C.sub.14 cyclic alkyl and C.sub.4-C.sub.14 cyclic alkyl oxy, said UHMWPE being characterized by molecular weight ranging between 3 and 17 million g/mole, bulk density ranging between 0.3 and 0.4 g/cc, intrinsic viscosity ranging between 20 and 65 dl/g, average particle size ranging between 155 and 165 microns and molecular weight distribution ranging between 10 and 14.

10. The process as claimed in claim 9, wherein said hydrocarbon medium of steps (iii) and (iv) are same or different.

11. The process as claimed in claim 9, wherein said step of polymerization after incorporating said heterogeneous Ziegler-Natta catalyst system is carried out at a temperature ranging between 70 C. and 80 C.

12. The process as claimed in claim 7, wherein said titanium halide is at least one selected from the group consisting of titanium chloride, titanium bromide, titanium iodide and titanium fluoride.

13. The process as claimed in claim 7, wherein said magnesium compound is at least one selected from the group consisting of magnesium halide, magnesium oxide, magnesium hydroxyl halides and magnesium salts of inorganic oxygen containing acids.

14. The process as claimed in claim 7, wherein said organo-aluminum compound is at least one selected from the group consisting of triethyl aluminum, tridecyaluminum, tri-n-butyl aluminum, tri-isopropyl aluminum, tri-isoprenyl aluminum, tri-isobutyl aluminum hydride, ethyl aluminumsesquichloride, diethyl aluminum chloride, di-isobutyl aluminum chloride, triphenyl aluminum, tri-n-octyl aluminium and tri-n-decyl aluminum.

Description

DETAILED DESCRIPTION

(1) In accordance with one aspect of the present disclosure, there is provided a heterogeneous Ziegler-Natta catalyst system that comprises at least one procatalyst, at least one co-catalyst, at least one hydrocarbon medium and at least one external donor.

(2) The procatalyst of the present disclosure comprises at least one titanium halide as a catalyst and at least one magnesium compound as a base (support). The catalyst of the present disclosure, i.e. the titanium halide includes but is not limited to titanium chloride, titanium bromide, titanium fluoride and titanium iodide. The magnesium compound or the base acts as a support for the catalyst and includes but is not limited to magnesium halide, magnesium oxide, magnesium hydroxyl halides and magnesium salts of inorganic oxygen containing acids. Typically, the ratio of the catalyst to the base ranges between 1.1:1.5 and 0.8:1.2. The elemental magnesium, the elemental titanium and the halide, together form the procatalyst and the ratio of elemental magnesium to elemental titanium to halide, in the procatalyst, is 1:1.3:3.7.

(3) The co-catalyst of the present disclosure comprises at least one organo-aluminum compound that includes but is not limited to triethyl aluminum, tridecyaluminum, tri-n-butyl aluminum, tri-isopropyl aluminum, tri-isoprenyl aluminum, tri-isobutyl aluminum hydride, ethyl aluminumsesquichloride, diethyl aluminum chloride, di-isobutyl aluminum chloride, triphenyl aluminum, tri-n-octyl aluminium and tri-n-decyl aluminum. Typically, the ratio of the organo-aluminum compound to the procatalyst ranges between 9:15 and 1.2:0.8. Further, the ratio of elemental aluminum, present in the organo-aluminum compound to elemental titanium, present in the procatalyst, ranges between 6:1 and 12:1.

(4) The hydrocarbon medium of the present disclosure includes but is not limited to pentane, hexane, cyclohexane, methyl cyclohexane, heptane, octane, nonane, decane; isopentane, varsol and their isomers thereof. Typically, varsol is a mixture of hydrocarbons, mostly linear alkanes, with boiling points ranging from 140 C. to 170 C. mostly to scavenge the impurities in the polymerization medium. It is present in an amount ranging between 0.4 and 0.6 l per 0.1 mmole of the catalyst.

(5) The external donor of the present disclosure comprises at least one organo-silane compound represented by Formula I.

(6) ##STR00004##

(7) Typically, the R.sub.1, R.sub.2, R.sub.3 and R.sub.4 of the organo-silane compound is at least one selected from the group consisting of C.sub.1-C.sub.14 branched or straight chain alkyl, C.sub.1-C.sub.14 branched or straight chain alkyl oxy, substituted or unsubstituted aryl, substituted or unsubstituted aryl oxy, C.sub.4-C.sub.14 cyclic alkyl and C.sub.4-C.sub.14 cyclic alkyl oxy. The ratio of the organo-silane compound to the procatalyst ranges between 1:10 and 10:1. Further, the ratio of elemental silicon, present in the organo-silane compound, to elemental titanium, present in the procatalyst, ranges between 1:10 and 10:1. Typically, the organo-silane compound includes but is not limited to tetraethoxysilane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, isobutylisopropyldimethoxysilane, n-propyltriethoxysilane, isobutyltriethoxysilane, phenyltriethoxysilane, diisopropyldimethoxysilane, diethyldimethoxysilane, diisobutyldimethoxysilane, aminopropyltriethoxysilane, diphenyldimethoxysilane and methyltrimethoxysilane. The inclusion of the organo-silane donor results in an enhancement in the properties of the polymer that is prepared by using the donor-modified Ziegler Natta catalyst.

(8) In accordance with another aspect of the present disclosure, there is provided a process for the preparation of the afore-stated heterogeneous Ziegler-Natta catalyst system. The first step of the process includes titanating at least one magnesium compound with at least one titanium halide, followed by allowing the titanium halide to bond with the magnesium compound, to obtain a mixture comprising at least one procatalyst. Typically, the ratio of the magnesium compound to the titanium halide ranges between 0.8:1.2 and 1.1:1.5. In the resultant mixture comprising the procatalyst, the ratio of elemental magnesium to elemental titanium to halide is 1:1.3:3.7. The magnesium compound of the present disclosure includes but is not limited to magnesium halide, magnesium oxide, magnesium hydroxylhalide and magnesium salt of inorganic oxygen containing acids. Further, the titanium halide includes but is not limited to titanium chloride, titanium bromide, titanium fluoride and titanium iodide.

(9) The next step includes separating and washing the resultant mixture comprising the procatalyst to obtain a procatalyst.

(10) The procatalyst is then admixed with at least one organo-aluminum compound as a co-catalyst, to obtain an activated catalyst. The organo-aluminum compound includes but is not limited to triethyl aluminum, tridecyl aluminum, tri-n-butyl aluminum, tri-isopropyl aluminum, tri-isoprenyl aluminum, tri-isobutyl aluminum hydride, ethyl aluminum sesquichloride, diethyl aluminum chloride, di-isobutyl aluminum chloride, triphenyl aluminum, tri-n-octyl aluminium and tri-n-decyl aluminum. The step of admixing is carried out in the presence of at least one hydrocarbon medium that includes but is not limited to pentane, hexane, cyclohexane, methyl cyclohexane, heptane, octane, nonane, decane, isopentane, varsol and isomers thereof. Typically, the ratio of the organo-aluminum compound to the procatalyst ranges between 9:15 and 1.2:0.8. Also, the ratio of elemental aluminum, present in the organo-aluminum compound to elemental titanium, present in the procatalyst, ranges between 6:1 and 12:1.

(11) Subsequently, at least one organo-silane compound is added to the activated catalyst, in a controlled manner to provide a heterogeneous Ziegler-Natta catalyst system. The organo-silane compound is represented by Formula 1 and acts as an external donor.

(12) ##STR00005##

(13) Typically, the R.sub.1, R.sub.2, R.sub.3 and R.sub.4 of the organo-silane compound is at least one selected from the group consisting of C.sub.1-C.sub.14 branched or straight chain alkyl, C.sub.1-C.sub.14 branched or straight chain alkyl oxy, substituted or unsubstituted aryl, substituted or unsubstituted aryl oxy, C.sub.4-C.sub.14 cyclic alkyl and C.sub.4-C.sub.14 cyclic alkyl oxy. The organo-silane compound includes but is not limited to tetraethoxysilane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, isobutylisopropyldimethoxysilane, n-propyltriethoxysilane, isobutyltriethoxysilane, phenyltriethoxysilane, diisopropyldimethoxysilane, diethyldimethoxysilane, diisobutyldimethoxysilane, aminopropyltriethoxysilane, diphenyldimethoxysilane and methyltrimethoxysilane. The organo-silane is added in a controlled manner to a stirred solution of the activated catalyst to achieve uniform modification of the catalyst sites. The addition is carried out in the presence of at least one hydrocarbon medium, under inert conditions, at a temperature ranging between 25 C. and 30 C. The time period of addition ranges between 2 and 10 minutes in laboratory and pilot scales, which can be proportionally increased when working in plant scale. The time may vary within the afore-stated range as the donor addition under gentle agitation of the activated catalyst solution ensures homogeneous and uniform catalyst modification. Typically, the ratio of the organo-silane compound to the procatalyst ranges between 1:10 and 10:1 and the ratio of elemental silicon, present in the organo-silane compound to elemental titanium, present in the procatalyst, ranges between 1:10 and 10:1. Typically, the hydrocarbon medium used in the process of the present disclosure is same or different.

(14) In accordance with yet another aspect of the present disclosure, there is provided a process for the preparation of an UHMW polyolefin. The first step of the process includes titanating at least one magnesium compound with at least one titanium halide, followed by allowing said titanium halide to bond with said magnesium compound, to obtain a mixture comprising at least one procatalyst. Typically, the ratio of the magnesium compound to the titanium halide ranges between 0.8:1.2 and 1.1:1.5. In the resultant mixture comprising the procatalyst, the ratio of elemental magnesium to elemental titanium to halide is 1:1.3:3.7. The magnesium compound of the present disclosure includes but is not limited to magnesium halide, magnesium oxide, magnesium hydroxylhalide and magnesium salt of inorganic oxygen containing acids. Further, the titanium halide includes but is not limited to titanium chloride, titanium bromide, titanium fluoride and titanium iodide.

(15) The next step includes separating and washing the resultant mixture comprising the procatalyst to obtain a procatalyst.

(16) The procatalyst is then admixed with at least one organo-aluminum compound as a co-catalyst, to obtain an activated catalyst. The organo-aluminum compound includes but is not limited to triethyl aluminum, tridecyl aluminum, tri-n-butyl aluminum, tri-isopropyl aluminum, tri-isoprenyl aluminum, tri-isobutyl aluminum hydride, ethyl aluminum sesquichloride, diethyl aluminum chloride, di-isobutyl aluminum chloride, triphenyl aluminum, tri-n-octyl aluminium and tri-n-decyl aluminum. The step of admixing is carried out in the presence of at least one hydrocarbon medium that includes but is not limited to pentane, hexane, cyclohexane, methyl cyclohexane, heptane, octane, nonane, decane, isopentane, varsol and isomers thereof. Typically, the ratio of the organo-aluminum compound to the procatalyst ranges between 9:15 and 1.2:0.8. Also, the ratio of elemental aluminum, present in the organo-aluminum compound to elemental titanium, present in the procatalyst, ranges between 6:1 and 12:1.

(17) Subsequently, at least one organo-silane compound is added to the activated catalyst, in a controlled manner to provide a heterogeneous Ziegler-Natta catalyst system. The organo-silane compound is represented by Formula 1 and acts as an external donor.

(18) ##STR00006##

(19) Typically, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 of the organo-silane compound is at least one selected from the group consisting of C.sub.1-C.sub.14 branched or straight chain alkyl, C.sub.1-C.sub.14 branched or straight chain alkyl oxy, substituted or unsubstituted aryl, substituted or unsubstituted aryl oxy, C.sub.4-C.sub.14 cyclic alkyl and C.sub.4-C.sub.14 cyclic alkyl oxy. The organo-silane compound includes but is not limited to tetraethoxysilane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, isobutylisopropyldimethoxysilane, n-propyltriethoxysilane, isobutyltriethoxysilane, phenyltriethoxysilane, diisopropyldimethoxysilane, diethyldimethoxysilane, diisobutyldimethoxysilane, aminopropyltriethoxysilane, diphenyldimethoxysilane and methyltrimethoxysilane. The organo-silane is added in a controlled manner to a stirred solution of the activated catalyst to achieve uniform modification of the catalyst sites. The addition is carried out in the presence of at least one hydrocarbon medium, under inert conditions, at a temperature ranging between 25 C. and 30 C. The time period of addition ranges between 2 and 10 minutes in laboratory and pilot scales, which can be proportionally increased when working in plant scale. The time may vary within the afore-stated range as the donor addition under gentle agitation of the activated catalyst solution ensures homogeneous and uniform catalyst modification. Typically, the ratio of the organo-silane compound to the procatalyst ranges between 1:10 and 10:1 and the ratio of elemental silicon, present in the organo-silane compound to elemental titanium, present in the procatalyst, ranges between 1:10 and 10:1.

(20) Typically, the hydrocarbon medium used in the process of the present disclosure is same or different.

(21) The next step is the polymerization reaction which includes incorporating the aforementioned heterogeneous Ziegler-Natta catalyst system in at least one monomer to obtain an UHMW polyolefin. The polymerization is carried out at a temperature ranging between 30 C. and 125 C., under ethylene pressure (pressure of ethylene monomer used during polymerization) ranging between 2 bar and 10 bars, followed by agitation at a speed ranging between 300 and 700 revolutions per minute. Typically, the ratio of the catalyst system and the monomer ranges between 1:20 and 1:220. Further, the monomer includes but is not limited to ethylene, propylene, butylene and other -olefins. Even further, the step of polymerization after incorporating the catalyst system is carried out at a temperature ranging between 70 C. and 80 C.

(22) The polyolefin prepared by the process of the present disclosure is characterized in that the molecular weight ranges between 3 and 17 million g/mole, the bulk density ranges between 0.3 and 0.4 g/cc, intrinsic viscosity ranging between 20 and 65 dl/g, average particle size ranging between 155 and 165 microns and molecular weight distribution ranges between 10 and 14.

(23) The addition of the organo-silane donor in the afore-stated quantities modifies the active sites in the catalyst (titanium) as well as the support (magnesium compound), enabling the polymerization to follow a modified kinetic profile, thereby resulting in the production of UHMWPE with increased bulk density and intrinsic viscosity. Along with the increase in the bulk density, a controlled and uniform particle size distribution with the desired average particle size and narrow molecular weight distribution is observed. The enhancement of the polymer characteristics depends on the type of silane donor used which influences the complexation ability with the catalyst. The donor of the present disclosure stabilizes the oxidation state of the metal in the catalyst through chelation with the Lewis acids such as Ti species in different oxidation states and aluminum alkyl. Other than the type of the donor, the donor to elemental titanium ratio and also the operating pressure are also crucial for achieving the property enhancement. Typically, higher pressures of ethylene ranging from 5 to 7.5 bars improve the productivity and also further increase the molecular weight of the polymer. The donor modified catalyst system electronically as well as geometrically (stereospecifically) influences the UHMWPE properties such as intrinsic viscosity and molecular weight distribution as determined from RDA (Rheometric Dynamic Analyzer).

(24) The present disclosure will now be discussed in the light of the following non-limiting embodiments:

Example 1: Preparation of UHMW Polyolefins Without the Addition of an External Donor to the Catalyst System

(25) A procatalyst of composition Mg:Ti:Cl::1:1.3:3.7 was taken, where the Ti was 100% tetravalent and had an average particle size of 6 to 7 microns diameter. Simultaneously, an admixture was formed by mixing 0.206 g of TEAL (co-catalyst) in 500 ml of varsol (polymerization medium). TEAL was added to scavenge the impurities in the medium, besides providing the Al/Ti molar ratio of 112, required during polymerization. 0.028 g (1.4 ml of the catalyst slurry equivalent to 0.028 g of catalyst which is further equivalent to 0.164 mmole of Ti) of the afore-stated procatalyst was added to the admixture to lead to in-situ reduction of the tetravalent Ti to trivalent Ti, within a time period of 42 minutes, at 25-30 C. temperature, under nitrogen pressure.

(26) The process of polymerization was started using ethylene as a monomer. The pressure (ethylene) was made to range between 2 and 7.5 bars, with 751 C. as the polymerization temperature. A suitable kinetic profile resulting in an exotherm ranging between 9 and 30 C. was derived and maintained by adjusting the input and output temperatures of the heating source and the reactor. The agitation was maintained at 50050 rpm for 2.250.25 hours. The resultant UHMW polyolefins had intrinsic viscosity of about 24.1-25.3 dl/g corresponding to an ASTM molecular weight of about 3.5-4.5 million g/mole.

Example 2: Preparation of UHMW Polyolefins with the Addition of an External Donor to the Catalyst System

(27) A procatalyst of composition Mg:Ti:Cl::1:1.3:3.7 was taken, where the Ti was 100% tetravalent and had an average particle size of 6 to 7 microns diameter. Simultaneously, an admixture was formed by mixing 0.206 g of TEAL (co-catalyst) in 500 ml of varsol (polymerization medium). TEAL was added to scavenge the impurities in the medium, besides providing the Al/Ti molar ratio of 112, required during polymerization. 0.028 g (1.4 ml of the catalyst slurry equivalent to 0.028 g of catalyst which is further equivalent to 0.164 mmole of Ti) of the afore-stated procatalyst was added to the admixture to lead to in-situ reduction of the tetravalent Ti to trivalent Ti, immediately followed by addition of tetraethoxy silane (TEOS) as an organo-silane donor such that the molar ratio of the donor to the procatalyst ranged from 0.5 to 9. The addition was carried out at 25-30 C. temperature, under nitrogen atmosphere for a time period ranging between 42 minutes, resulting in in-situ chelation between the Titanium, Lewis acid and Lewis base species; thereby generating the heterogeneous Ziegler-Natta catalyst system of the present disclosure.

(28) The process of polymerization was started using ethylene as a monomer. The pressure (ethylene) was made to range between 2 and 7.5 bars, with 751 C. as the polymerization temperature. A suitable kinetic profile resulting in an exotherm ranging between 5 and 20 C. (significantly lower than in Example 1) was derived and maintained by adjusting the input and output temperatures of the heating source and the reactor. The agitation was maintained at 50050 rpm for 2.250.25 hours. The resultant UHMW polyolefins had intrinsic viscosity from 27 to 52 dl/g corresponding to an ASTM molecular weight of about 5 to 12 million g/mole.

Example 3: Effect of Different Organo-Silane Donors in Modifying the Catalyst and Impacting the Polymer Properties

(29) The effect of different organo-silane donors in modifying the catalyst and resulting in different polymer characteristics is depicted below (Table 1). The donors evaluated were (TEOS) tetraethoxysilane, (C-donor) cyclohexylmethyldimethoxysilane, (D-donor) dicyclopentyldimethoxysilane, (IBIPDMS) isobutylisopropyldimethoxysilane, (NPTES) n-propyltriethoxysilane, (IBTES) isobutyltriethoxysilane, (PTES) phenyltriethoxysilane, (DIPDMS) diisopropyldimethoxysilane, (DEDMS) diethyldimethoxysilane, (DIBDMS) diisobutyldimethoxysilane, (APTES) aminopropyltriethoxysilane, (DPDMS) diphenyldimethoxysilane and (MTMS) methyltrimethoxysilane

(30) TABLE-US-00001 TABLE 1 Effect of different organo-silane donors in modifying the catalyst and impacting the polymer properties Donor/Ti IV (dl/g) Molecular weight Silane molar of UHMWPE (ASTM) of UHMWPE Donor ratio obtained obtained (million g/mole) TEOS 4 31 5.9 DPDMS 5.0 26.9 4.9 D-donor 4.0 33.1 6.5 C-donor 1.0 23.2 4.0 MTMS 2.0 23.2 4.0 IBIPDMS 4.0 28.9 5.4 NPTES 4.0 29.8 5.6 IBTES 4.0 37.3 7.6 PTES 4.0 45.1 9.9 DIPDMS 4.0 42.3 9.1 DEDMS 4.0 50.0 11.4 DIBDMS 4.0 51.2 11.8 APTES 4.0 52.2 12.1

(31) The polymerization conditions maintained were as follows: 0.5 l varsol; about 9% TEAL solution in hexane as a co-catalyst; Ti from catalyst=0.164 mmole; Al/Ti about 9-12; D=Organo silane donors (10% solution in Hexane); 75 C.; 2 hr; 500 rpm; Ethylene pressure=2.5 bars; 1 l Buchi-glasuster polylcave glass reactor.

(32) Mode of addition: Varsol (polymerization medium)+TEAL (co-catalyst)+procatalyst+D (donor); Equilibration time5 min.

Example 4: Effect of Donor/Ti Ratio in Modifying the Catalyst and Impacting the Polymer Properties

(33) The effect of Donor/Ti ratio in impacting the IV and molecular weight is given in Table 2 for the donor TEOS. It was observed that as the Donor/Ti ratio increased the molecular weight and IV also increased. This observation provided a very good handle to control and achieve the desired IV and molecular weight of the UHMWPE produced.

(34) TABLE-US-00002 TABLE 2 Effect of Donor/Ti ratio in modifying the catalyst and impacting the polymer properties Molecular Bulk Average UHMWPE IV weight (M) density particle g/g of Donor/Ti (dl/g) (ASTM) (g/cc) size () catalyst 0 - 17.6 2.7 0.3402 169 7027 control 0.5 18.3 2.9 0.3658 166 6795 1.0 20.6 3.4 0.3625 159 5405 2.0 25.3 4.5 0.3602 161 5212 4.0 31 5.9 0.3638 156 3900

(35) The polymerization conditions maintained were as follows: 0.5 l varsol; about 9% TEAL solution in hexane as co-catalyst; Ti from catalyst=0.164 mmole; Al/Ti about 9-12; D=TEOS donor (10% solution in Hexane); 75 C.; 2 hours; 500 rpm; Ethylene pressure=2.5 bars; 1 l Buchi-glasuster polylcave glass reactor.

(36) Mode of addition: Varsol (polymerization medium)+TEAL (co-catalyst)+Catalyst+D (donor); Equilibration time5 min.

Example 5: Effect of Ethylene Pressure in Modifying the Catalyst and Impacting the Polymer Properties

(37) The effect of ethylene pressure in impacting the IV and molecular weight is given below for the donor TEOS (tetraethoxy silane) at a specific Donor/Ti ratio4.0 (Table 3). It can be seen that as the ethylene pressure increased the molecular weight and IV also increased. This also provides a very good handle to control and achieve the desired IV and molecular weight of the UHMWPE produced.

(38) TABLE-US-00003 TABLE 3 Effect of ethylene pressure in modifying the catalyst and impacting the polymer properties D/Ti; IV MW (M) Medium & ethylene donor (dl/g) (ASTM) pressure 4.0; TEOS 31.7 6.1 Varsol; 2.5 bars 4.0; TEOS 34.7 6.9 Varsol; 5.0 bars 4.0; TEOS 43.1 9.3 Varsol; 7.5 bars 4.0; TEOS 26.6 4.8 Hexane; 4.0 bars 4.0; TEOS 40.3 8.5 Hexane; 7.5 bars

(39) The polymerization conditions maintained were as follows: 0.5 l varsol or hexane; about 9% TEAL solution in hexane as a co-catalyst; Ti from catalyst=0.164 mmole; Al/Ti about 9-12; D=TEOS donor (10% solution in Hexane); 75 C.; 2 hours; 500 rpm; Ethylene pressure varied from 2.5 to 7.5 bars; 1 l Buchi-glasuster polylcave glass reactor.

(40) Mode of addition: Varsol or hexane as the polymerization medium+TEAL (co-catalyst)+Catalyst+D (donor); Equilibration time5 min.

Example 6: Effect of Donor in Narrowing Down MWD as Observed from Rheometry

(41) The molecular weight and molecular weight distribution of the UHMWPE samples were studied by rheometry and the results are tabulated in Table 4.

(42) Dynamic rheometry of the UHMW polyethylene samples was carried out at 190 C. keeping the strain at 2% and the measurements were made in the frequency range of 0.01-100 rad/s. 25 mm parallel plate assembly was employed for the analysis. The melt rheological data were used to obtain molecular weight and molecular weight distribution data using the Orchestrator software. It was found that the donor modified catalyst is able to narrow down the molecular weight distribution by 40%.

(43) TABLE-US-00004 TABLE 4 Effect of donor in narrowing down MWD UHMWPE sample TEOS donor (D) Mw MWD From control expt. using non None 6.67M 19.77 modified catalyst From control expt. using non None 5.81M 21.77 modified catalyst From control expt. using non None 3.40M 11.26 modified catalyst From experiment using TEOS Donor/Ti = 0.5 3.2M 10.90 donor modified catalyst From experiment using TEOS Donor/Ti = 2.0 5.5M 13.40 donor modified catalyst From experiment using TEOS Donor/Ti = 4.0 6.82M 13.91 donor modified catalyst

(44) The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

(45) The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

(46) The polyolefins prepared in accordance with the present disclosure have very high molecular weight and intrinsic viscosity, better bulk density and uniform particle size distribution.

(47) Further, the polyolefins prepared in accordance with the present disclosure have lower average particle size as derived from the uniform particle size distribution and lower molecular weight distribution (lowering by greater than 40%).

(48) Further, the catalyst used for making UHMWPE with molecular weight in the range of 3.5 to 4.5 million g/mole, can be easily modified just by the addition of the requisite quantity of the silane donor such as TEOS, to produce UHMWPE with molecular weight as high as 16 million g/mole.

(49) Even further, the process of the present disclosure obviates the use of costly single site/metallocene catalyst systems and methylalumoxane as an activator for achieving such high molecular weights, thereby making the process economical and environment friendly.

(50) Still further, the use of the Ziegler-Natta catalyst of the present disclosure prevents fouling of the reactor as in case of conventional processes.

(51) Throughout this specification the word comprise, or variations such as comprises or comprising, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

(52) The use of the expression at least or at least one suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results.

(53) The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention and the claims unless there is a statement in the specification to the contrary.

(54) While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications in the process or compound or formulation or combination of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.