Claims:1) A non-phthalate based Ziegler-Natta catalyst composition for olefin polymerization, said catalyst composition comprising:
a) a pro-catalyst comprising a spheroidal magnesium compound, a group-IVB metal component and an internal electron donor; wherein the amount of the internal electron donor ranges from 10 to 30% on mass basis of the pro-catalyst;
b) an organo-aluminium co-catalyst;
c) an external electron donor; and
d) a hydrocarbon solvent;
wherein, the internal electron donor is 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate and the external electron donor is at least one dimethoxysilane compound.
2) The catalyst composition as claimed in claim 1, wherein the group-IVB metal component is at least one titanium component selected from the group consisting of TiCl4, Ti(OC2H5)3Cl, Ti(OC3H7)3Cl, Ti(OC4H9)Cl3 and TiCl2; wherein the amount of the group-IVB metal component on elemental metal basis in the pro-catalyst is in the range from 1 to 5% on mass basis.
3) The catalyst composition as claimed in claim 1, wherein the magnesium compound is at least one selected from the group consisting of magnesium dichloride, magnesium methoxide, magnesium ethoxide and magnesium iso-propoxide; wherein the amount of the magnesium compound on elemental magnesium basis in the pro-catalyst ranges from 10 to 30% on mass basis.
4) The catalyst composition as claimed in claim 1, wherein the organo-aluminium co-catalyst is at least one selected from the group consisting of triethylaluminium, tridecylaluminium, tri-n-butylaluminium, tri-isopropylaluminium, tri-isoprenylaluminium, tri-isobutylaluminium, ethyl aluminium sesquichloride, diethylaluminium chloride, di-isobutyl aluminium chloride, triphenylaluminium, tri-n-octylaluminium and tri-n-decylaluminium; and the molar ratio of the amount of the group-IVB metal component and the amount of the organo-aluminium co-catalyst ranges from 1:50 to 1:500.
5) The catalyst composition as claimed in claim 1, wherein the external electron donor is dicyclopentyldimethoxysilane; and the molar ratio of the amount of the organo-aluminium co-catalyst and the amount of the external electron donor ranges from 1:1 to 20:1.
6) The catalyst composition as claimed in claim 1, wherein the hydrocarbon solvent is at least one selected from a group consisting of hexane and decane.
7) A process for the preparation of a non-phthalate based Ziegler-Natta catalyst composition, said process comprising the following steps:
a. reacting a spheroidal magnesium compound with a mixture of a group-IVB metal component, chlorobenzene and an internal electron donor at a temperature in the range from 80 to 110?C for a time period of 15 to 150 minutes to obtain a first suspension; decanting the first suspension to obtain a supernatant and a first residue;
b. adding the first residue to a mixture of TiCl4 and chlorobenzene, and heating to obtain a second suspension; decanting the second suspension to obtain a supernatant and a second residue;
c. mixing the second residue with TiCl4, chlorobenzene, and benzoyl chloride, and heating to obtain a third suspension; decanting the third suspension to obtain a supernatant and a third residue; washing the third residue with a solvent and drying to obtain the Zigler-Natta pro-catalyst; and
d. mixing the Zigler-Natta pro-catalyst, an organo-aluminium co-catalyst and a external electron donor in at least one hydrocarbon solvent selected from the group consisting of hexane and decane, and stirring to obtain the non-phthalate based Ziegler-Natta catalyst composition.
8) A process for olefin polymerization using the non-phthalate based Ziegler-Natta catalyst composition as claimed claim 1, said process comprising the following steps:
a. feeding the catalyst composition into a reactor;
b. introducing a predetermined volume of an olefin selected from a group consisting of ethylene and propylene in the reactor to attain a predetermined olefin pressure; and
c. subjecting the olefin in the reactor to polymerization in the presence of a chain termination agent at a temperature ranging from 60 to 100 °C to obtain a polyolefin selected from the group consisting of polyethylene and polypropylene.
9) The process as claimed in claim 8, wherein the chain termination agent is hydrogen.
10) Polypropylene obtained by the process claimed in claim 8, wherein said polypropylene is characterized by:
(a) melt flow index ranging from 3.0 to 8.0 g/10 min; and
(b) polydispersity index ranging from 4.0 to 8.0. , Description:FIELD OF INVENTION
The present invention relates to a non-phthalate based Ziegler-Natta catalyst composition for olefin polymerization.
BACKGROUND OF INVENTION
Polyolefins, such as polypropylene and polyethylene, are extensively used in various aspects of daily life, such as textiles, stationery, automotive components, plastic parts and reusable containers. Polyolefins can be prepared by polymerization of olefins in the presence of a Ziegler-Natta catalyst composition.
The Ziegler-Natta catalyst composition contains an electron donor system, which comprises an internal electron donor and an external electron donor. The electron donor system influences the catalytic activity of the Ziegler-Natta Catalyst composition and properties of the polyolefin produced during the polymerization process.
Ziegler-Natta catalyst compositions containing an alkyl phthalate, as an electron donor, are widely used for the polymerization of olefin. Some amount of the alkyl phthalate inadvertently gets incorporated in the polyolefin produced during the polymerization process. The presence of even a small amount of alkyl phthalate in the polyolefin is not appropriate, since alkyl phthalates are toxic in nature. High doses of certain phthalates have been shown to change the hormone levels and cause birth defects in rodents. Di-(2-ethylhexyl)phthalate (DEHP) has been classified as a Category 1A reprotoxin and is now on Annexure XIV of the European Union's REACH legislation.
Therefore, the use of phthalates in the preparation of Ziegler-Natta catalyst compositions should be avoided.
Thus, there exists a need to provide a non-phthalate based Ziegler-Natta catalyst composition for olefin polymerization.

OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide a non-phthalate based Ziegler-Natta catalyst composition.
Another object of the present disclosure is to provide a process for olefin polymerization in the presence of the non-phthalate based Ziegler-Natta catalyst composition.
Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.
SUMMARY
In accordance with one aspect of the present disclosure, there is provided a non-phthalate based Ziegler-Natta catalyst composition for olefin polymerization. The electron donor system used for the preparation of the non-phthalate based Ziegler-Natta catalyst composition comprises 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate as an internal electron donor and at least one dialkoxysilane as an external electron donor.
In accordance with another aspect of the present disclosure there is provided a process for the preparation of the non-phthalate based Ziegler-Natta catalyst composition.
Polypropylene, characterized by melt flow index, ranging from 3.0 to 8.0 g/10 min and polydispersity index, ranging from 4.0 to 8.0, is obtained using the non-phthalate based Ziegler-Natta catalyst composition.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
A non-phthalate based Ziegler-Natta catalyst composition will now be described with the help of the accompanying drawings, in which:
Figure-1(a) depicts the morphology of the conventional pro-catalyst prepared by using diisobutyl phthalate (DIBP).
Figure-1(b) depicts the morphology of the pro-catalyst prepared by using 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate in accordance with the present disclosure.
Figures-2(a)-(c) depict the morphology of the polypropylene prepared by using a non-phthalate based Ziegler-Natta catalyst composition without an external electron donor.
Figures-3(a)-(c) depict the morphology of the polypropylene prepared by using a non-phthalate based Ziegler-Natta catalyst composition with Aluminium to external electron donor molar ratio of 3:1.
Figures-4(a)-(c) depict the morphology of the polypropylene prepared by using a non-phthalate based Ziegler-Natta catalyst composition with Aluminium to external electron donor molar ratio of 5:1.
DETAILED DESCRIPTION
The polyolefin prepared by polymerization of an olefin in the presence of phthalate-based Ziegler-Natta catalyst compositions contain some amount of phthalate, which is toxic in nature. In order to prepare polyolefin that is relatively less toxic, the present disclosure envisages the preparation of non-phthalate based Ziegler-Natta catalyst compositions.
In accordance with one aspect of the present disclosure, there is provided a non-phthalate based Ziegler-Natta catalyst composition for olefin polymerization. The polyolefin produced by the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure is relatively less toxic as compared to the polyolefin produced by phthalate based Ziegler-Natta catalyst compositions. Further, polymerization in the presence of the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure proceeds with a high hydrogen response and produces polyolefin having a high melt flow index (MFI) grade.
The non-phthalate based Ziegler-Natta catalyst composition of the present disclosure comprises a pro-catalyst, an organo-aluminium co-catalyst, an external electron donor and a hydrocarbon solvent.
The pro-catalyst comprises a spheroidal magnesium compound, a group-IVB metal component and an internal electron donor.
The amount of the internal electron donor in the pro-catalyst is in the range from 10 to 30% on mass basis. The internal electron donor is 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate.
In accordance with one embodiment of the present disclosure, the amount of the internal electron donor in the pro-catalyst is 16.4% on mass basis.
The group-IVB metal component is a titanium component. The titanium component is selected from the group consisting of TiCl4, Ti(OC2H5)3Cl, Ti(OC3H7)3Cl, Ti(OC4H9)Cl3 and TiCl2.
In accordance with one embodiment of the present disclosure, the titanium component is TiCl4.
The amount of the group-IVB metal component on the elemental metal basis in the pro-catalyst is in the range from 1 to 5% on mass basis.
In accordance with one embodiment of the present disclosure, the amount of the group-IVB metal component in the pro-catalyst is 2.5% on mass basis.
The magnesium compound is at least one selected from the group consisting of magnesium dichloride, magnesium methoxide, magnesium ethoxide and magnesium iso-propoxide.
The amount of the magnesium compound on elemental magnesium basis in the pro-catalyst is in the range from 10 to 30% on mass basis.
In accordance with one embodiment of the present disclosure, the amount of the magnesium compound on elemental magnesium basis in the pro-catalyst is 18.9% on mass basis.
The organo-aluminium co-catalyst is at least one selected from the group consisting of triethylaluminium, tridecylaluminium, tri-n-butylaluminium, tri-isopropylaluminium, tri-isoprenylaluminium, tri-isobutylaluminium, ethyl aluminium sesquichloride, diethylaluminium chloride, di-isobutyl aluminium chloride, triphenylaluminium, tri-n-octylaluminium and tri-n-decylaluminium.
In accordance with one embodiment of the present disclosure, the organo-aluminium co-catalyst is triethylaluminium.
The molar ratio of the amount of the group-IVB metal component and the amount of the organo-aluminium co-catalyst ranges from 1:50 to 1:500.
In accordance with one embodiment of the present disclosure, the molar ratio of the amount of the group-IVB metal component and the amount of the organo-aluminium co-catalyst is 1:250.
The external electron donor is at least one dimethoxysilane compound.
In accordance with one embodiment of the present disclosure, the external electron donor is dicyclopentyldimethoxysilane (DCPDMS).
The molar ratio of the amount of the organo-aluminium co-catalyst and the amount of the external electron donor ranges from 1:1 to 20:1.
In accordance with one embodiment of the present disclosure, the molar ratio of the amount of the organo-aluminium co-catalyst and the amount of the external electron donor is 3:1.
In accordance with another embodiment of the present disclosure, the molar ratio of the amount of the organo-aluminium co-catalyst and the amount of the external electron donor is 5:1.
The hydrocarbon solvent is at least one selected from a group consisting of hexane and decane.
In accordance with one embodiment of the present disclosure, the hydrocarbon solvent is hexane.
In accordance with another aspect of the present disclosure there is provided a process for the preparation of a non-phthalate based Ziegler-Natta catalyst composition of the present disclosure. The process comprises the following steps:
The first step of the preparation of the composition involves reacting a spheroidal magnesium compound with a mixture of a group-IVB metal component, chlorobenzene and an internal electron donor at a temperature in the range from 80 to 110 ?C for a time period of 15 to 150 minutes to obtain a first suspension, and decanting the first suspension to obtain a supernatant and a first residue.
The second step involves adding the first residue to a mixture of TiCl4 and chlorobenzene, and heating to obtain a second suspension and decanting the second suspension to obtain a supernatant and a second residue.
The third step involves mixing the second residue with TiCl4, chlorobenzene and benzoyl chloride and heating, to obtain a third suspension; and decanting the third suspension to obtain a supernatant and a third residue. The third residue is washed with a solvent and dried to obtain a Ziegler-Natta pro-catalyst.
The fourth step involves mixing the Ziegler-Natta pro-catalyst, an organo-aluminium co-catalyst and an external electron donor in at least one hydrocarbon solvent selected from the group consisting of hexane and decane to obtain the envisaged non-phthalate based Ziegler-Natta catalyst composition of the present disclosure.
The solvent used for washing the third residue is at least one selected from a group consisting of hexane and decane, preferably hexane.
In accordance with an aspect of the present disclosure, there is provided a process for olefin polymerization using the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure. The process comprises the following steps:
The first step of the process involves feeding the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure into a reactor.
The second step of the process involves introducing a predetermined amount of an olefin selected from a group consisting of ethylene and propylene in the reactor to attain a predetermined olefin pressure in the reactor.
The third step of the process involves subjecting the olefin in the reactor to polymerization in the presence of a chain termination agent at a temperature ranging from 60 to 100 °C to obtain a polyolefin selected from the group consisting of polyethylene and polypropylene, typically polypropylene.
In accordance with one embodiment of the present disclosure, the polymerization is performed under 5 Kg/cm2 pressure of propylene.
In accordance with one embodiment of the present disclosure, the chain termination agent is hydrogen.
In accordance with one embodiment of the present disclosure, the polymerization is performed at 70 °C.
In accordance with one embodiment of the present disclosure, the polymerization is performed for a time period of 2 hours.
Polypropylene obtained by the polymerization of propylene in the presence of the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure is characterized by melt flow index, ranging from 3.0 to 8.0 g/10 min and polydispersity index, ranging from 4.0 to 8.0.
In accordance with one embodiment of the present disclosure, the melt flow index of the polypropylene is 6.4 g/10min. In accordance with another embodiment of the present disclosure, the melt flow index of the polypropylene is 4.6 g/10min.
In accordance with one embodiment of the present disclosure, the polydispersity index of the polypropylene is 7.8. In accordance with another embodiment of the present disclosure, the polydispersity index of the polypropylene is 6.6.
The characteristics of the polyolefin resins produced by polymerization process depend upon the characteristics of the Ziegler-Natta catalyst composition, which, in turn, depends upon the characteristics of the pro-catalyst. The characteristics of the pro-catalyst depend upon the composition of the pro-catalyst.
The characteristics of the pro-catalyst of the present disclosure were compared with the characteristics of the phthalate based pro-catalyst prepared using diisobutyl phthalate (DIBP). It was found that the particles of the pro-catalyst of the present disclosure were more uniform in shape and have a smoother surface as compared to the pro-catalyst prepared with diisobutyl phthalate (DIBP).
Ziegler-Natta catalyst compositions were prepared using both pro-catalysts mentioned herein above and polymerization of olefin was carried out in the presence of these two Ziegler-Natta catalyst compositions. The characteristics of the polyolefin prepared in the presence of non-phthalate based Ziegler-Natta catalyst compositions of the present disclosure were compared with the characteristics of a phthalate based Ziegler-Natta catalyst compositions prepared using diisobutyl phthalate (DIBP).
The non-phthalate based Ziegler-Natta catalyst compositions of the present disclosure produced polyolefin with higher MFI as compared to the Ziegler-Natta catalyst compositions containing DIBP.
Furthermore, the atactic portion, in the polyolefin prepared using the non-phthalate based Ziegler-Natta catalyst compositions of the present disclosure, was found to be lower as compared to the polyolefin produced using the Ziegler-Natta catalyst compositions containing DIBP.
Still further, it was found that the molecular weight distribution range of the polyolefin resins prepared using the non-phthalate based Ziegler-Natta catalyst compositions of the present disclosure was broader than the polyolefin resins produced using the Ziegler-Natta catalyst compositions containing DIBP.
It was also found that the non-phthalate based Ziegler-Natta catalyst compositions of the present disclosure are capable of producing polyolefin having high melt flow index with comparatively lower hydrogen consumption during polymerization.
The polypropylene resins produced in the presence of the non-phthalate based Ziegler-Natta catalyst compositions of the present disclosure were found to have a spherical shape with smooth surfaces. This may be due to the uniform catalyst fragmentation taking place at a controlled rate of polymer growth on the surfaces of the catalyst particles that result in the uniform spherical shape of the resin particles.
Polyolefin resins with smooth surfaces and spherical shape show better flow properties as they have a lower surface area to volume ratio, thereby resulting in minimum friction between particles in motion. A probable reason for obtaining resins with this morphology is because of the use of spheroidal magnesium compound as a precursor for the catalyst. Uniform polyolefin resins are preferred in the gas phase polymerization.
Examples provided herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skilled in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The laboratory scale experiments provided herein can be scaled up to industrial or commercial scale.
Examples:
The Ziegler-Natta pro-catalyst of the present disclosure (referred hereinafter as catalyst-2) based on spheroidal magnesium alkoxide precursor was synthesized by using 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate as the internal electron donor.
For comparison, a phthalate-based Ziegler-Natta pro-catalyst containing diisobutyl phthalate (DIBP) (referred hereinafter as catalyst-1) as the internal electron donor was prepared.
Structures of the internal electron donors, 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate and DIBP, used for the preparation of Ziegler-Natta pro-catalysts are shown in Table 1.
Table 1: Structures of the internal electron donors
Sr. Internal electron donor Structure
1 (for comparison) Diisobutyl phthalate (DIBP)
2 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate (CD1)

Example 1 Steps (a), (b), and (c): Preparation of the pro-catalyst
Step-(a): Spheroidal magnesium alkoxide (10 gm) was added to a 1:1 v/v mixture of TiCl4 and chlorobenzene (230 ml) followed by 1.1 gm (0.00312 moles) of the internal electron donor and the resulting mixture was stirred and heated at 97 °C for 60 minutes to obtain first suspension. The stirring was stopped and the reaction mixture was allowed to settle and cool. The supernatant was decanted and the first residue, thus obtained, was taken to the step (b).
Step-(b): A 1:1 v/v mixture of TiCl4 and chlorobenzene (230 mL) was added to the first residue and the resulting mixture was stirred and heated at 97 °C for 30 minutes to obtain a second suspension. Stirring was stopped and the reaction mixture was allowed to settle and cool, and the supernatant was decanted to obtain second residue.
Step-(c): A 1:1 v/v mixture of TiCl4 and chlorobenzene (230 mL) was added to the second residue followed by the addition of 0.5 ml benzoyl chloride and the resulting mixture was stirred and heated at 97 °C for 30 minutes. Stirring was stopped and the reaction mixture was allowed to settle and cool, and the supernatant was decanted. The residue thus obtained was washed 5 times with 100 mL n-hexane to remove excess titanation material. The solid was dried to get the Ziegler-Natta pro-catalyst. Composition and particle size of the pro-catalysts are shown in Table-2.
Table-2: Composition and particle size of the pro-catalyst
Component Unit Catalyst-1 (DIBP) Catalyst-2 (CD1)
Titanium as Ti wt% 2.6 2.5
Magnesium as Mg wt% 18.5 18.9
Chloride as Cl wt% 58.9 56.5
Donor wt% 13.2 16.4
D-10 µm 4 7
D-50 µm 23 22
D-90 µm 47 32
Mean µm 24 22

The D-10, D-50 and D-90 values of the pro-catalyst containing DIBP (Catalyst-1) were found to be 4, 23 and 47 µm respectively with a mean value of 24 µm. Whereas, the D-10, D-50 and D-90 values of the pro-catalyst of the present disclosure (Catalyst-2) were found to be 7, 22 and 32 µm respectively with a mean value of 22 µm.
The above data indicates that the particle size distribution of the pro-catalyst of the present disclosure is more uniform than that of the pro-catalyst containing DIBP.
Morphology of the pro-catalyst of the present disclosure is shown in Figure-1(a) and that of the pro-catalyst containing DIBP is shown in Figure-1(b). These figures indicate that the pro-catalyst of the present disclosure has a uniform shape and smooth surface as compared to the pro-catalyst containing DIBP.
Step d): Preparation of Ziegler-Natta catalyst Composition from the pro-catalyst obtained in step (c)
The pro-catalyst obtained in step (c) was mixed with dried n-decane to obtain a slurry containing 70 mg/ml of the pro-catalyst. Dilute triethylaluminium (TEAL) (10%) was added to the slurry to obtain a mixture and left for 5 min. The molar ratio of TEAL and elemental titanium (TEAL/Ti) was 250. This step was followed by the addition of predetermined amounts of dicyclopentyldimethoxysilane (DCPDMS) (external electron donor) to the mixture and stirring for 5 min to obtain the Ziegler-Natta catalyst composition.
A set of three Ziegler-Natta catalyst compositions having the molar ratios of TEAL to dicyclopentyldimethoxysilane (DCPDMS), hereinafter referred to as (Al/ED), of 0, 3 and 5 were prepared for catalyst-1 and catalyst-2. The Al/ED ratio of 0 indicates that the Ziegler-Natta catalyst compositions do not contain external electron donor.
Polymerization of olefin was carried out in the presence of these Ziegler-Natta catalyst compositions by the procedure mentioned herein below.
Example 2: Process for olefin polymerization using catalyst-1 and catalyst-2
The Ziegler-Natta catalyst compositions prepared in example-1 were employed for polymerization of propylene. A slurry of a Ziegler-Natta catalyst composition was prepared in hexane as solvent in a reactor. Propylene was introduced in the reactor till a constant propylene pressure of 5 Kg/cm2 was achieved. Polymerization of the propylene was carried out for 2 hours at 70 °C in the presence of 240 mL of hydrogen as a molecular weight controlling agent.
The Ziegler-Natta catalyst compositions containing DIBP and 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate as internal electron donor and having an Al/ED ratio of 0, 3 and 5 were employed for the polymerization of propylene under similar conditions. The polypropylene produced in each case was dried and characterized for its melt flow index (MFI), xylene soluble (XS) fraction and particle size distribution. The data is provided in Table-3.
Table 3: Characterization of polymer resin synthesized using catalyst-1 and catalyst-2
Run No. Solid Catalyst system Internal donor External donor Al/ED Activity (Kg PP/g cat) MFI
(g/10min) XS
(wt%) BD (g/cc) APS (µm)
1 Catalyst-1 DIBP DCPDMS 0 4.1 20.3 13.5 0.41 Agglomerate
2 5 9.7 1.7 1.6 0.42 255
3 3 9.2 1.4 1.2 0.40 272
4 Catalyst-2 CD1 DCPDMS 0 6.4 49.1 5.9 0.42 283
5 5 3.0 6.4 1.1 0.42 224
6 3 2.2 4.6 1.0 0.44 280
Key: Al/ED: ratio of the amount of co-catalyst as elemental aluminium and the amount of external electron donor; DCPDMS: dicyclopentyldimethoxysilane, BD: Bulk density; XS: Xylene soluble; MFI: Melt flow index; APS = average particle size; CD1: 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate.
(i) Polymerization using Ziegler-Natta pro-catalyst compositions without external electron donor (entries 1 and 4 in Table 3)
When polymerization was carried out without using an external electron donor (entries 1 and 4 in Table-3), catalyst-2 showed higher activity as compared to catalyst-1. Thus, the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure has higher catalytic activity as compared to the Ziegler-Natta catalyst composition containing DIBP, when polymerization was carried out without an external electron donor. Further, it was found that the hydrogen response (represented by MFI in Table 3) of the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure is significantly higher as compared to the Ziegler-Natta catalyst composition containing DIBP.
Furthermore, the atactic portion (represented by XS in Table 3) in the polypropylene produced using catalyst-2 is lower than that produced with catalyst-1. This data indicates that the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure is more stereospecific as compared to the Ziegler-Natta catalyst composition containing DIBP when polymerization was carried out without using an external donor.
From the data in Table-3 and structures of DIBP and CD-1, it is evident that the steric factor plays an important role in governing the activity of the Ziegler-Natta catalyst composition.
Still further, the data indicate that non-phthalate based Ziegler-Natta catalyst composition is capable of producing high melt flow polypropylene product with lower hydrogen consumption.
(ii) Polymerization using Ziegler-Natta catalyst composition containing external electron donor (entries 2, 3, 5 and 6 in Table 3)
The external electron donor used for the preparation of Ziegler-Natta catalyst compositions was dicyclohexyldimethoxysilane.
When polymerization is carried out in the presence of an external electron donor, catalyst-2 showed lower productivity as compared to catalyst-1. This data indicates that in the presence of an external donor, the catalytic activity of the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure is lower than that of the Ziegler-Natta catalyst composition containing DIBP.
The lower activity of non-phthalate based Ziegler-Natta catalyst composition of the present disclosure can be compensated by carrying out the polymerization at high monomer pressure.
Further, it was found that the hydrogen response of the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure is significantly higher as compared to the Ziegler-Natta catalyst composition containing DIBP. The hydrogen response of catalyst-2 is three to four times higher than that of catalyst-1. This data indicates that the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure demand less amount of hydrogen for the synthesis of isotactic polypropylene.
The MFI of the polypropylene, produced using the non-phthalate based Ziegler-Natta catalyst compositions of the present disclosure in the presence of an external electron donor, was found to be in the moderate range which is beneficial for preparing propropylene articles.
The atactic portion of the polymer produced using catalyst-1 and catalyst-2 in the presence of the external electron donor was found to be in the range from 1.0 to 1.6 weight%. The bulk densities of polymer resins produced under these conditions were in the range from 0.40 to 0.45 g/cc.
Morphology of polyolefin resins
The morphology of the polypropylene resins prepared using the non-phthalate based Ziegler-Natta catalyst compositions of the present disclosure containing different external electron donor concentrations were studied with the scanning electron microscope (SEM).
The representative SEM images of the resin particles at various magnifications are shown in Figure-2, Figure-3 and Figure-4. Figures 2 (a), (b) and (c) are captured at the magnifications of 100X, 352X and 1000X, respectively. Figures 3 (a), (b) and (c) are captured at the magnifications of 200X, 500X and 1000X respectively. Figures 4 (a), (b) and (c) are captured at the magnifications of 200X, 500X and 1000X respectively.
The SEM images show that the polypropylene resins, prepared using the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure, have a smooth surface and spherical shape.
Properties of polypropylene
Thermal properties
The thermal characteristics of the polypropylene resins prepared using the Ziegler-Natta catalyst compositions containing different external electron donor concentrations were studied by the differential scanning calorimetry (DSC).
A comparison of the melting point of the polymers produced using catalyst-1 and catalyst-2 are shown in Table-4.

Table 4: Melting point of polymer resin synthesized using catalyst-1 and catalyst-2
Run No. Solid Catalyst system Internal donor ED Al/ED Melting point (?C)
1 Catalyst-1 DIBP DCPDMS 0 156.4
2 5 162.3
3 3 164.1
4 Catalyst-2 CD1 DCPDMS 0 159.9
5 5 163.9
6 3 163.4
Key: ED: External electron donor; DCPDMS: dicyclopentyldimethoxysilane, CD1: 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate.
The melting point of the resins prepared using the Ziegler-Natta catalyst compositions containing external electron donor were found to be in the range from 162.3 to 164.1 ?C.
The melting point of the resins prepared using the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure in the presence of the external electron donor was found to be similar to that produced using the Ziegler-Natta catalyst composition containing DIBP.
A comparison of the crystallization point of the polymers produced using catalyst-1 and catalyst-2 are shown in Table 5.

Table 5: Crystallization point of polymer resin synthesized using catalyst-1 and catalyst-2
Run No. Solid Catalyst system Internal donor ED Al/ED Crystallization point (?C)
1 Catalyst-1 DIBP DCPDMS 0 108.3
2 5 113.1
3 3 113.9
4 Catalyst-2 CD1 DCPDMS 0 109.3
5 5 113.3
6 3 113.1
Key: ED: External electron donor; DCPDMS: dicyclopentyldimethoxysilane, CD1: 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate.
The crystallization point of the resin prepared using the Ziegler-Natta catalyst composition without an external electron donor was found to be 108.3 to 109.3 ?C for catalyst-1 and catalyst-2, respectively. The crystallization point of the resins prepared using the Ziegler-Natta catalyst compositions containing external electron donor were found to be in the range from 113.1 to 113.9 ?C.
The crystallization point of the resins prepared using the non-phthalate based Ziegler-Natta catalyst composition of the present disclosure in the presence of the external electron donor was found to be similar to that produced using the Ziegler-Natta catalyst composition containing DIBP.
Polydispersity index
The polydispersity index of the polypropylene is represented as molecular weight distribution. The molecular weight distribution of the polypropylene resins is calculated as the ratio of mass average molar mass and number average molar mass.
The molecular weight of resins prepared using the Ziegler-Natta catalyst compositions containing different donor concentrations were studied on Gel permeation chromatography (GPC) having infra-red (IR) and light scattering detector. The molecular weight and molecular weight distribution of the polypropylene prepared using catalyst-1 and catalyst-2 are shown in Table-6.
Table-6: Molecular weight and molecular weight distribution of polymer resin synthesized using catalyst-1 and catalyst-2
Run
No.
Solid
Catalyst
System Internal
donor
ED Al/ED
Mw X 10 5
(g/mol) Mn X 10 5
(g/mol) Mw/Mn

1 Catalyst-1 DIBP DCPDMS 3 3.5 0.8 4.4
2 Catalyst-2 CD1 DCPDMS
3 4.0 0.5 7.8
3 5 3.6 0.6 6.6
Key: ED: External electron donor; DCPDMS: dicyclopentyldimethoxysilane, CD1: 3,5-diisopropyl-1,2-phenylene diethyl dicarbonate, Mw : mass average molar mass, Mn : Number average molar mass.
The polymer resin synthesized using non-phthalate based Ziegler-Natta catalyst compositions of the present disclosure showed a broad molecular weight distribution and hence higher polydispersity index than that produced using catalyst-1.
TECHNICAL ADVANCEMENT
The technical advancements offered by the present disclosure include the realization of:
• a simplified process to prepare non-phthalate based Ziegler-Natta catalyst compositions having uniform morphology;
• non-phthalate based Ziegler-Natta catalyst compositions, producing polyolefin without toxic phthalate traces;
• non-phthalate based Ziegler-Natta catalyst compositions, producing polyolefin with controlled shape and size;
• non-phthalate based Ziegler-Natta catalyst compositions, producing polyolefin with improved hydrogen response and high MFI reactor grade resins;
• non-phthalate based Ziegler-Natta catalyst compositions, producing polyolefin having broad molecular weight distribution; and
• non-phthalate based Ziegler-Natta catalyst compositions, producing polyolefin high isotactic portion.
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.

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 disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.