BE1021588B1 - PROCESS FOR THE PREPARATION OF PROPYLENE POLYMER - Google Patents

Abstract

Disclosed is a propylene polymerization process, which can prepare a propylene homopolymer having both high fluidity and high stiffness as well as a propylene / α-olefin copolymer having both high fluidity and good stiffness. rigidity-toughness balance by controlling the polymerization steps and raising the polymerization temperature, while the catalyst still maintains a relatively high polymerization activity.

Description

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Process for the preparation of propylene polymer

Technical area

The present invention relates to a process for the preparation of a propylene polymer, more particularly to a process for the preparation of a propylene homopolymer having a high creep number and a high rigidity as well as a propylene copolymer / α-olefin having both a high creep index and a good stiffness-toughness balance.

Related Art

Most propylene polymer products can be used for injection molding articles, and widely applied in many fields such as packaging, transportation, home appliances, automobiles, office supplies, household goods and medical articles. There are two trends for the development of high performance propylene polymer products. The first trend is to increase the creep index (MFR, also called hot creep index (MFI)) of a polymer, which can help shorten the molding time, reduce energy consumption, and manufacture large thin-walled items. Currently, injection productions with a MFR of 10 to 15 g / 10 min are gradually replaced by products having an MFR of 25 to 35 g / 10 min. The second trend is to strike a balance between the stiffness and impact resistance of propylene polymers, so as to meet the impact resistance requirements of the propylene copolymers while improving stiffness, and thus the thickness of the product can be improved. be reduced and the cost of producing articles can also be reduced. Since propylene polymers having a high creep index can shorten the molding time, reduce energy consumption, meet the impact resistance requirements and increase the stiffness of propylene polymers, such propylene polymers having a reduced high creep index have predominant advantages

Z U increased product yield, decreased product cost, and produced large, thin-walled, complex articles. v -

The following methods are generally used to increase the MFR of propylene polymers: (1) Use of a catalyst system responsive to molecular weight regulation in a polymerization process. By selectively combining different catalysts, cocatalysts and external electron donors, the polymerization catalyst system becomes more sensitive to the molecular weight regulator (for example, hydrogen gas which is the most common molecular weight regulator), so that the polymer products having a high MFR can be obtained in the presence of a small amount of hydrogen gas. (2) Addition in the polymer of a degradation agent after the polymerization.

One or more peroxides are generally added so that the polymer chains in the polymer are broken under certain conditions to increase the MFR of the product. This technique is generally called controlled rheology technology.

Currently, many devices for the production of polypropylene utilize the increased amount of hydrogen gas to produce propylene copolymer products having a high MFR, but the amount of hydrogen gas added is limited due to the pressure limitation. nominal devices, as is the case with the present process of polymerization propylene mass in liquid phase. The addition of a large quantity of hydrogen gas can lead to the following defects: a significant decrease in the activity of the catalyst; a decrease in the isotacticity of the polymers, leading to a decrease in rigidity of the final polypropylene articles; and furthermore, the existence of a large amount of hydrogen gas, which is a non-condensable gas, degrades the heat exchange heat transfer effect of the system, so that the production load of the device is directly influenced and therefore, the production efficiency decreases. There are also processes in which the amount of the hydrogen gas used is reduced by choosing a combination of different catalysts, cocatalyst and external electron donors, for example, the process as described in CN101270172A. The method described by this invention can improve the sensitivity to hydrogen regulation of propylene polymerization and render the isotacticity and polypropylene MFR achieved adjustable in a relatively wide range, but the use of a catalyst sensitive to the regulation by hydrogen generally leads to the decrease of the isotacticity and the degradation of the equilibrium rigidity-toughness of the final product.

Current polymerization processes can hardly meet the requirements of polymerization activity, sensitivity to hydrogen regulation, and high isotacticity and high creep index of propylene polymers. In order to meet the high isotacticity and creep requirements of the polypropylene products, propylene copolymers having a high MFR are generally produced by controlled rheology technology, i.e., using a method of adding a small amount of peroxide degrading agents to obtain propylene copolymers having a high creep index. Due to the degradation of the products caused by the peroxide, the polypropylene articles generally have an unpleasant odor and therefore their applications are significantly limited.

It is known that in olefin polymerization processes, Ziegler-Natta catalysts have many advantages with raising the olefin polymerization temperature. For example, as for the propylene polymerization, with the polymerization temperature rise, the catalysts become more sensitive to the molecular weight regulator (eg, hydrogen gas), so that polymers having a low molecular weight can be generated, even in the presence of a very small amount of hydrogen gas, this being very favorable for the production of polypropylene products having a high creep index. In addition, with the increase of the polymerization temperature, the isotacticity of the polypropylene generated is also improved, this being very favorable for the production of propylene homopolymer product having a high rigidity and of propylene copolymer having rigidity properties. -rightly balanced toughness. Currently, a quantity of nucleating agent is generally required to improve the stiffness of polymer products, which leads to the increase in the cost of production. Therefore, it is an ideal option to improve the quality of

Polypropylene products by raising the polymerization temperature.

For example, Chinese Patent No. CN 0457790C discloses a polymerization process, which comprises the three-step polymerization: (1) propylene prepolymerization, (2) low temperature polymerization, (3) high temperature polymerization. In this process, the polymerization temperature is progressively raised and the proportion of polymers in each polymerization step is controlled so as to obtain propylene polymers having high flexural moduli and high flexural strength. However, since the use of the low temperature polymerization in step (2) consumes most of the polymerization activity of the catalyst, the improvement of the polymer properties that should be induced by the high polymerization temperature is not fully achieved.

In addition, conventional Ziegler-Natta catalysts have a limitation of adaptation to the polymerization temperature. In general terms, when the polymerization temperature exceeds 85 ° C, the catalyst activity generally decreases rapidly if no treatment is applied. In particular, when the polymerization temperature is above 100 ° C, the polymerization activity generally decreases so as to render the process useless in industrial application.

In summary, there is yet no corresponding propylene polymerization and catalyst process that can meet the requirements on polymerization activity, high isotacticity of polymers, and improved hydrogen control property so that propylene polymers having high fluidity and rigidity can be prepared while the catalyst still maintains high polymerization activity.

BRIEF DESCRIPTION OF THE INVENTION The object of the present invention is to solve the disadvantages in the prior art ζυ in that the requirements in terms of polymerization activity, sensitivity to hydrogen regulation and creep index, Rigidity and impact resistance can not be met simultaneously during the production of propylene polymers having a high creep index, and to describe a process for preparing propylene polymers that can take all of these requirements into account.

The present invention relates to a process for preparing propylene polymers, comprising the steps of: (1) conducting a prepolymerization of propylene or a mixture of olefins containing propylene and other comonomer (s) of olefin in a gaseous phase or a liquid phase in the presence of a Ziegler-Natta catalyst at -10 ° C to 50 ° C and 0.1 to 10.0 MPa to obtain a propylene prepolymer, the prepolymerization multiplication being controlled in the range of 2 to 3000 g of polymer / g of catalyst, preferably of 3 to 2000 g of polymer / g of catalyst; (2) conducting propylene homopolymerization or copolymerization of propylene and other α-olefin comonomer (s) in a gaseous phase in the presence of the propylene prepolymer as obtained in step (1) under conditions of from 91 to 150 ° C, preferably from 91 to 130 ° C and more preferably from 91 to 110 ° C and from 1 to 6 MPa to obtain a propylene polymer, the polymerization time being from 0.5 to 4 hours; (3) continuation of the homopolymerization or copolymerization of propylene in a gaseous phase or a liquid phase in the presence of the product as obtained in step (2) under conditions of 50 to 150 ° C and 1 to 6 MPa.

In addition, the present invention further relates to a propylene homopolymer and a copolymer of propylene and other α-olefin comonomer (s) which are prepared by the process for the polymerization of propylene according to the present invention.

Detailed description of the invention

The following terms and definitions thereof are applied to the entire text of the description and claims of the present invention.

In the present invention, the term "prepolymerization multiplication" refers to a ratio of the prepolymer weight to the weight of the solid catalyst component as initially added. Generally, as for intermittent prepolymerization, the prepolymerization multiplication may be calculated from the division of the prepolymer weight as directly measured by the weight of catalyst as added; as for the continuous prepolymerization, the prepolymerization multiplication can be indirectly controlled by regulating the residence time and the polymerization temperature of the reaction. For different catalysts, different polymerization temperatures, different polymerization methods (gaseous phase, bulk liquid phase, etc.) and different polymerization pressures, the prepolymerization multiplications may be different even if the same residence time in the prepolymerization may be used, and can be obtained by integral calculation depending on the reaction kinetics curve of the catalyst.

In the present invention, the term "weight ratio of polymers reacted in steps (2) and (3)" refers to a ratio of the weight of the polymers generated in the propylene polymerization in step (2) to the weight of polymers generated in the polymerization of propylene and other α-olefin comonomer (s) in step (3). According to the present invention, although the weight ratio of the polymers in steps (2) and (3) is not specifically limited, the weight ratio of the polymers in steps (2) and (3) may preferably be 0.3 to 3, more preferably 0.5 to 2, still more preferably 1.0 to 2.0 and 0.8 to 1.5, in terms of isotacticity and creep index of propylene copolymer .

According to the present invention, the melt flow rate MFR of the polymer is measured according to ISO 1133 under conditions of 230 ° C. and 2.16 kg of filler.

In the process according to the present invention, the steps can be carried out in a single reactor for the batch polymerization operation, or carried out in different reactors for the continuous polymerization operation.

In one embodiment of the process of the present invention, in step (1), the prepolymerization temperature is controlled in the range of -10 ° C to 50 ° C, preferably 0 to 30 ° C, more preferably from 10 to 25 ° C. The prepolymerization pressure is 0.1 to 10.0 MPa, preferably 1.0 to 6.0 MPa, more preferably 1.5 to 5.5 MPa. The reaction time of this step depends on the desired degree of polymerization, which may be, for example, 8 to 16 minutes, preferably 10 to 14 minutes.

According to the present invention, the phase state of the propylene in the prepolymerization of step (1) is not particularly limited, and the prepolymerization can be carried out in the gas phase or in the liquid phase. Preferably, the prepolymerization in step (1) is conducted in the liquid phase, in particular in bulk liquid phase prepolymerization. During bulk liquid phase prepolymerization, a full tank operation can be used and the prepolymerization multiplication can be controlled with the residence time and the reaction temperature, so that a continuous operation can be easily performed to to reduce the cost of operation. In this process, the prepolymerization multiplication is from 2 to 3000 g of polymer / g of catalyst, preferably from 3 to 2000 g of polymer / g of catalyst, more preferably from 3 to 1000 g of polymer / g of catalyst.

In another embodiment of the process of the present invention, in step (2), the polymerization is conducted in the presence of the prepolymer as obtained in step (1), the polymerization temperature being 91 to 150 ° C, preferably 91 to 130 ° C, more preferably 91 to 110 ° C and particularly 91 to 105 ° C, and the polymerization pressure is 1 to 6 MPa, preferably 2 to 4 MPa, more preferably from 2 to 3 MPa. The reaction time can be controlled in the range of, for example, 40 to 90 minutes, preferably 50 to 70 minutes. In this step, homopolymerization of propylene in the gas phase is preferably conducted.

The reaction may be conducted by a gas phase polymerization process, and may be conducted in a reaction vessel or a plurality of reaction vessels in series. Although the type of reaction vessel is not specifically limited, the gas phase polymerization is preferably conducted in a horizontal gas phase reaction vessel. The horizontal reaction vessel comprises a horizontal agitation shaft and uses a coolant to remove heat. Depending on the mass of the reaction and the heat transfer property as well as the physicochemical parameters of the propylene polymers, the horizontal gas phase reaction vessel is controlled with a stirring speed of 10 to 150 rpm. preferably from 10 to 100 rpm, and more preferably from 20 to 50 rpm. The shape of the stirring blade can be a T-shape, a rectangle shape, an inclined blade, a door shape, a beveled shape and a combination thereof. The reaction time or polymerization residence time is 0.5 to 4 hours. The creep index of the polymer can be regulated with a molecular weight regulator. Under the polymerization conditions of step (2), the polymer obtained has an MFR of 10 to 2000 g / 10 min, preferably 15 to 1000 g / 10 min, more preferably 20 to 1000 g / 10 min, and most preferably 30 to 500 g / 10 min.

In one embodiment of the present invention, as for the polymerization in step (3), in the presence of the product as obtained in step (2), homopolymerization or copolymerization of propylene occurs in one phase. gaseous at 55 to 110 ° C and at a reaction pressure of preferably 1.5 to 4 MPa, and more preferably 1.5 to 2.5 MPa, the reaction time being 30 to 90 min, more preferably from 35 to 45 minutes. In the present invention, the polymerization temperature of step (3) is advantageously substantially controlled below the polymerization temperature of step (2).

According to the present invention, the copolymerization of propylene and other α-olefin comonomer (s) can be carried out preferably in step (3). Although the type of α-olefin is not specifically limited in the present invention and different α-olefins capable of copolymerization with propylene in the art can be used in the present invention, the α-olefin is preferably one or several of ethylene, butylenes and hexylene, more preferably ethylene. The amount of other α-olefin comonomer (s) is not specifically limited, but the other α-olefin comonomer (s), in. ethylene is used in an amount of 4 to 40% by weight, preferably 6 to 30% by weight.

Weight, relative to the weight of the propylene homopolymer obtained in step (2).

The weight ratio of the polymers of steps (2) and (3) is from 0.3 to 3.0. In the polymerization process of the present invention, the weight ratio of the polymers reacted in step (2) and step (3) is preferably greater than 1, preferably 1.0 to 2.0. After the polymerization of step (3), the obtained polymer has an MFR flow index of 1 to 500 g / 10 min, preferably 5 to 300 g / 10 min, more preferably 8 to 200 g / 10 min. and most preferably from 10 to 150 g / 10 min.

In the polymerization process of the present invention, the Ziegler-Natta catalyst may be any Ziegler-Natta catalyst as known in the art. Preferably, the catalyst comprises a reaction product of the following components: (1) a solid catalyst component containing titanium; (2) an alkyl aluminum compound; and (3) optionally, an external electron donor component.

Component (1) is a reaction product of contacting an alkoxy-magnesium compound, a titanium compound and an internal electron donor compound.

The titanium compound is selected from at least one compound of the formula: Ti (OR) 4-nXn, wherein R is selected from an aliphatic or aromatic C1-C14 hydrocarbonyl group (e.g., a C7-C14 aromatic hydrocarbonyl group ), X is a halogen atom, n is an integer of 0 to 4; and in the case where n is equal to or less than 2, the existing R groups may be the same or different. Said halogen atom can be chlorine, bromine or iodine.

For example, the titanium compound is at least one selected from a group consisting of tetraalkoxy titanium, titanium tetrahalide, alkoxy titanium trihalide, dialkoxy titanium dihalide, and trialkoxy titanium monohalide. More specifically, said tetraalkoxy-titanium is at least one selected from a group consisting of tetramethoxy-titanium, tetraethoxy-titanium, tetra-n-propoxy-titanium, tetraisopropoxy titanium, tetra-n-butoxy titanium tetraisobutoxy titanium, tetra-cyclohexyloxy titanium, tetraphenoxy titanium;

Said titanium tetrahalide is at least one selected from a group consisting of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide; said alkoxy titanium trihalide is at least one selected from the group consisting of methoxy titanium trichloride, ethoxy titanium trichloride, propoxy titanium trichloride, n-butoxy titanium trichloride, ethoxy tribromide -titanium; said dialkoxy titanium dihalide is at least one selected from a group consisting of dimethoxy titanium dichloride, diethoxy titanium dichloride, di-n-propoxy titanium dichloride, di-iso-propoxy-titanium dichloride diethoxy titanium dibromide; said trialkoxy-titanium monohalide is at least one selected from a group consisting of trimethoxy titanium monochloride, triethoxy titanium monochloride, tri-n-propoxy titanium monochloride, tri-iso-propoxy titanium monochloride. Presently, titanium tetrahalide is preferred, and titanium tetrachloride is particularly preferred.

The internal electron donor compound is one or more selected from alkyl esters of aliphatic and aromatic monocarboxylic acids, alkyl esters of aliphatic and aromatic polycarboxylic acids, aliphatic ethers, cycloaliphatic ethers and the like. aliphatic ketones, preferably one or more selected from alkyl esters of saturated C 1 -C 4 aliphatic carboxylic acids, alkyl esters of C 7 -C 20 aromatic carboxylic acids, C 2 -C 6 aliphatic esters, C 3 -C 4 cyclic ethers, C 7 -C 15 saturated aliphatic ketones and 1,3-diether compounds.

Preferably, the internal electron donor compounds may be phthalic acid ester compounds of formula (III),

(III)

In the formula (III), R4 and R5 are the same or different, and denote, independently of one another, one selected from a linear or branched C1-C12 alkyl, a C3-C10 cyclic alkyl, a C 6 -C 20 alkylaryl and a substituted or unsubstituted aryl; R6, R7, R8 and R9 are hydrogen, or three of them are hydrogen, and the other is one selected from halogen, linear or branched alkyl with 1 to 4 carbon atoms and linear or branched alkoxy with 1 to 4 carbon atoms.

The compound of formula (III) is chosen from diethyl phthalate, di-n-butyl phthalate, di-isobutyl phthalate, dihexyl phthalate, diheptyl phthalate and di-isooctyl phthalate. More preferably, it is diethyl phthalate.

The internal electron donor compounds may also be chosen from 1,3-diether compounds of formula (IV),

(IV)

In formula (IV), Ru and R12 are the same or different, independently selected from linear, branched or cyclic C1-C20 aliphatic groups; R13, R14, R15, R18, R17 and R18 are the same or different, chosen independently from each other from hydrogen, halogen atoms and a linear or branched C1-C20 alkyl, a C3-C20 cycloalkyl, an aryl in Св-Сго, a C7-C20 alkylaryl and a C7-C20 arylalkyl, and optionally one or more of R13-R18 may be bonded to each other to form a ring.

Preferably, R11 and R12 are the same or different, independently selected from linear or branched C1-C6 alkyl; R15 and R16 are the same or different, independently selected from linear or branched C1-C10 alkyl, or C3-C10 cycloalkyl.

The diether compounds of formula (VI) are, without limitation: 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 9,9-di (methoxymethyl) fluorene, 2-isobutyl-2-isopropyl-1,3-dimethoxypropane, 2 , 2-dicyclopentyldimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, 2-isobutyl-2-isopropyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3 -methoxypropane and the like. The alkoxy-magnesium is at least one selected from the compounds of formula (II) Mg (OR 1) 2 -m (OR 2) m, wherein R 1 and R 2 are the same or different, independently selected from C 1-6 alkyl. Cs linear or branched, and 0 £ m 2.

Preferably, R 1 and R 2 are independently of each other selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, n-hexyl, (2-ethyl) hexyl; more preferably, R 1 is ethyl, R 2 is (2-ethyl) hexyl, and 0.001 m-0.5. it should be noted that the alkoxy magnesium represented by this formula represents only the composition of different alkoxy groups, i.e., their molar ratio, but does not illustrate the exact specific structure of alkoxy magnesium. *

The alkoxy magnesium compound has a spherical shape and a mean particle size (D50) of 10 to 150 μm, preferably 15 to 100 μm, more preferably 18 to 80 μm. In addition, its particle size index SPAN is <1.1, preferably <1.05, where SPAN is calculated by the following formula: SPAN = (D90-D10) / D50 (V) *

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In the formula (V), D 90 represents a particle diameter corresponding to a cumulative weight fraction of 90%, D 10 represents a particle diameter corresponding to a cumulative weight fraction of 10%, and D 50 represents a corresponding particle diameter. at a cumulative weight fraction of 50%.

The alkoxy-magnesium compound according to the present invention is prepared by reacting magnesium metal, alcohols corresponding to the alkoxy groups of formula (II) and mixed halogenating agent in an inert atmosphere at reflux, the molar ratio of metal from magnesium to halogen atoms in the mixed halogenating agent being from 1: 0.0002 to 1: 0.2, preferably from 1: 0.001 to 1: 0.08; the weight ratio of alcohol to magnesium being from 4: 1 to 50: 1, preferably from 6: 1 to 25: 1. The reaction temperature is 0 ° C at the reflux temperature of the reaction system. Preferably, the reaction temperature is the reflux temperature of the reaction system. The reaction time is 2 to 30 hours. The mixed halogenating agent is a combination of halogen and halogenated compound, which are selected from, for example, iodine, bromine, chlorine, magnesium chloride, magnesium bromide, magnesium iodide, potassium chloride, bromide potassium iodide, calcium chloride, calcium bromide, calcium iodide, mercuric chloride, mercuric bromide, mercuric iodide, ethoxy-magnesium iodide, methoxy-magnesium iodide, isopropoxy-magnesium iodide, hydrogen, chloroacetyl chloride, etc. The mixed halogenating agent is preferably a combination of iodine and magnesium chloride. The weight ratio of iodine to magnesium chloride is preferably from 1: 0.02 to 1:20, more preferably from 1: 0.02 to 1:10, more preferably from 1: 0.05 to 1: 20, most preferably 1: 0.1 to 1:10. The inert atmosphere comprises a nitrogen gas atmosphere, an argon gas atmosphere, preferably a nitrogen gas atmosphere.

The titanium-containing solid catalyst component of the present invention may be prepared by a process comprising the step of: reacting the alkoxymagnesium with the inner electron donor compound and the titanium compound in the presence of an inert diluent; washing the solid obtained in the reaction with an inert diluent to obtain the solid catalyst component. In this process, the amount of the titanium compound used, expressed in molar magnesium ratio in the alkoxy-magnesium compound, is (0.5-100): 1, preferably (1-50): 1, and the amount of the electron donor compound used, expressed as a magnesium molar ratio in the alkoxy magnesium compound, is (0.005-10): 1, preferably (0.01-1): 1. The amount of the inert diluent, expressed as a magnesium molar ratio in the alkoxy magnesium compound, is (0.5-100): 1, preferably (1-50): 1. The reaction temperature is -40 ° to 200 ° C, more preferably -20 ° C to 150 ° C, and the reaction time is 1 min to 20 h, more preferably 5 min to 8 h. The inert diluent may be at least one selected from an alkane or arene at C 7 -C, preferably at least one of hexane, heptane, octane, decane, benzene, toluene , xylene or derivatives thereof, more preferably toluene.

In the preparation of the solid catalyst component according to the present invention, the order of addition of the alkoxy magnesium carrier, the inner electron donor compound, the inert diluent and the titanium compound is not specifically limited. For example, these components may be mixed in the presence of the inert solvent, or they may be diluted with the inert diluent in advance and then mixed. It is not specifically limited the number of times that these components are mixed and thus, the mixing process can be performed, for example, one or more times.

The component (2) of the catalyst of the present invention is an alkyl aluminum compound of formula (VI), wherein R 10 is hydrogen or a hydrocarbyl with 1 to 20 carbon atoms, X is halogen and n is a number of 1. The compound of formula (VI) may be selected from a group consisting of triethyl aluminum, tripropyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, tri-n-octyl aluminum , diethylaluminum monohydride, diisobutylaluminum monohydride, diethylaluminum monochloride, diisobutylaluminum monochloride, ethylaluminum sesquichloride, ethylaluminum dichloride, preferably triethyl aluminum, tri-iso-butyl aluminum.

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(VI) v

In the catalyst according to the present invention, the external electron donor component may be any one of external electron donors known in the art, and therefore, is not specifically limited. This is preferably the organo-silicon compound of formula (VII),

(VII) wherein R1 "and R2" are the same or different, and, independently of each other, are one of halogen, hydrogen, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl and halogenated C1-C20 alkyl; R3 "is at each occurrence and independently one of C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl and halogenated C1-C20 alkyl, each of m" and n "is independently an integer of 0 at 3, and m "+ n" <4.

Non-limiting examples of the organosilicon compound can be trimethylmethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, isopropylisobutyldiméthoxysilane, di-tert-butyldimethoxysilane, tert-butylmethyldimethoxysilane, tert-butyléthyldiméthoxysilane, tert butylpropyldiméthoxysilane, tert-butylisopropyldiméthoxysilane, cyclohexylmethyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexyl-tert-butyldimethoxysilane , cyclopentylmethyldimethoxysilane, cyclopentyléthyldiméthoxysilane, dicyclopentyldimethoxysilane, cyclopentylcyclohexyldiméthoxysilane, di (2-methylcyclopentyl) dimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isopropyltriméthoxysilane, butyltrimethoxysilane, butyltriethoxysilane, isobutyltrimethoxysilane, pentyltrimethoxysilane, isopentyltriméthoxysilane, cyclopentyltrimét hoxysilane, cyclohexyltrimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane and the like. These organo-silicon compounds may be used alone or in combination of two or more of them. More preferably, the outer electron donating donor compound comprises at least one of dicyclopentyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, cyclohexylmethyldimethoxysilane, diphenyldimethoxysilane, methyltertbutyldimethoxysilane and tetraethoxysilane.

In the catalyst of the present invention, the molar ratio of the compound (2) to the component (1), i.e., the molar ratio of the alkyl aluminum to the solid catalyst component, expressed in Al / Ti is from 20 to 500: 1, preferably from 25 to 100: 1. The molar ratio of component (2) to component (3), expressed as Al / Si, is 1 to 200: 1, preferably 3 to 100: 1.

In addition, the present invention further relates to a propylene polymer as prepared by the process of the present invention. Raising the polymerization temperature in step (2) results in propylene polymers having both high fluidity and high rigidity. Such propylene polymer articles having high fluidity and high rigidity have the following advantages: for example, as with injection molding articles, increased fluidity can produce articles having a more complex structure; and because of the increased rigidity, the thickness of the articles can be reduced to reduce the cost of production. In parallel, the polymerization process of the present invention utilizes a specific type of catalyst, which has a still relatively high polymerization activity when used at a higher polymerization temperature, even after prepolymerization. Therefore, the present invention is very promising in industrial application.

Examples

The present invention is further illustrated in conjunction with the following examples, which are used to explain rather than limit the present invention.

Measurement Methods: 1. The titanium content in the catalyst is measured using a spectrophotometer 721. 2. The particle size and particle size of the alkoxy-magnesium particles and the catalyst are measured using a diffraction method. Malvern Mastersizer TM 2000 laser with n-hexane as dispersant (where, SPAN = (D90-D10) / D50). 3. Measurement of 2-ethylhexyloxy-magnesium in the support: a solution of 1N hydrochloric acid is added to the sample obtained, stirred for 24 hours for degradation, and the 2-ethylhexanol therein is quantified by gas chromatography and then calculation. 4. Measurement of the m-value of the support: 0.1 g of support is taken up, added to 10 ml of 1.2 mol / l aqueous hydrochloric acid solution and then stirred for 24 h for degradation. Ethanol and 2-ethylhexanol therein are quantitated by gas chromatography and then the value m is calculated by the following formula:

where w1 is the mass of 2-ethylhexanol, and w2 is the mass of ethanol. 5. The internal electron donor content in the olefin polymerization catalyst component is measured using a Waters 600E liquid chromatography system or gas chromatography. 6. The stereoregularity index (Isotacticity) is measured according to the National Standard GB2412. 7. The creep index (MFR) is measured according to NS01133 at 230 ° C under and 2.16 kg load. 8. The tensile strength of the resin is measured according to ASTM D638-00 9. The bending modulus of the resin is measured according to ASTM D790-97. 10. Izod impact strength is measured according to ASTM D256-00.

Preparation example 1> * -

In this preparation example, the solid catalyst component used in the process for preparing a propylene copolymer of the present invention is prepared.

In a pressure-resistant reactor of 161 with a stirrer which was sufficiently purged with nitrogen gas, 10 l of ethanol, 300 ml of 2-ethylhexanol, 11.2 g of iodine, 8 g of magnesium chloride and 640 g of magnesium powder are added. Under stirring, the system is refluxed until hydrogen gas is no longer discharged. The reaction is complete, and 3 l of ethanol are used for washing. The dialkoxy magnesium support is obtained after filtration and drying. The dialkoxy magnesium support has a D50 = 30.2 μm, a span value (Span) of 0.81, a m-value of 0.015. 650 g of the dialkoxy magnesium support and 3250 ml of toluene are formulated to form a suspension. In a 16 l pressure-resistant reactor which is purged repeatedly with high purity nitrogen gas, 2600 ml of toluene and 3900 ml of titanium tetrachloride are added and heated to 80 ° C. Then, the formulated slurry is added to the reactor, maintained at temperature for 1 h. After adding 130 ml of diethyl phthalate, the temperature is slowly raised to 110 ° C and held for a further 2 hours. A solid is obtained by filtration on press. The solid obtained was added to a 5070 ml toluene and 3380 ml titanium tetrachloride buffer and then treated with stirring at 110 ° C for 1 hour.

Such treatment is repeated 3 times. After filtration on press, the solid obtained is washed with hexane 4 times, 6000 ml by washing. The main solid catalyst component is finally obtained after press filtration and drying. The solid catalyst component obtained has an atomic titanium content of 2.4% by weight, and has a diethyl phthalate content of 10.5%.

Example 1 δ \

This example is intended to illustrate the propylene copolymer and the method of preparation thereof as described in the present invention. , v *. ' The test uses the polymerization process comprising a continuous prepolymerization tank in gaseous connection in series with two horizontal tanks. The prepolymerization vessel has a volume of 5 liters and is a vertical agitation vessel with a jacket cooling device. The stirring blade is an inclined blade of the turbine type, and the stirring speed is 500 rpm. The two horizontal gas-phase reaction vessels which are of the same structure have a volume of 0.2 m 3 and are horizontal stirring vessels with a stirring blade being a T-type inclined blade and having an angle of inclination of 10 °. The stirring speed is 100 rpm. The homopolymerization of propylene in the gas phase in step (2) and the gas phase copolymerization of propylene and of ethylene in step (3) are carried out respectively in two horizontal gas phase reaction vessels.

Prepolymerization of step (1): the reaction pressure is 2.5 MPa, the reaction temperature is 10 ° C, the reaction time is 12 minutes. The solid component as prepared in Preparative Example 1 is fed at a flow rate of 0.9 g / h, the triethylaluminum is fed at a flow rate of 0.072 mol / h, a mixture of dicyclopentyldimethoxysilane and tetraethoxysilane (1 4 mol / mol) is fed at a flow rate of 0.012 mol / h. Al / Si (mole / mole) = 6.0; and propylene is fed at a rate of 10 kg / h. The prepolymerization multiplication is about 80.

Homopolymerization of propylene gas phase in step (2): the reaction temperature is 95 ° C, the reaction pressure is 2.3 MPa and the reaction time is 60 minutes. Propylene is fed at a rate of 30 kg / h, the hydrogen gas is fed at a flow rate of 1.1 g / h, and the molar ratio of hydrogen gas / propylene in the reaction gas phase is 0.02.

Copolymerization of propylene and ethylene gas phase in step (3): the reaction temperature is 66 ° C, the reaction pressure is 2.3 MPa, and the reaction time is 40 min. Ethylene is fed at a flow rate of 7 kg / h, propylene is fed at a flow rate of 30 kg / h and the hydrogen gas is fed at a flow rate of 0.5 g / h. The molar ratio of hydrogen / propylene gas in the reaction gas phase is 0.01 and the molar ratio of ethylene / propylene in the gaseous phase of the reaction system is 0.35. The test is carried out continuously for 48 hours under the conditions of Example 1, and the operation of the device is stable. In the continuous experimental process, polymers in certain amounts are taken from the reaction vessels of steps (2) and (3) and analyzed. The results are shown in Table 1.

Example 2

This example is intended to illustrate the propylene copolymer and the method of preparation thereof as described in the present invention. The test uses the polymerization process comprising a continuous prepolymerization tank in gaseous connection in series with two horizontal tanks. The prepolymerization vessel has a volume of 5 liters and is a vertically stirred tank with jacket cooling device. The stirring blade is an inclined blade of the turbine type, and the stirring speed is 500 rpm. The horizontal gas phase reaction vessel has a volume of 0.2 m 3 and is a horizontal stirring vessel, the stirring blade being a T-type inclined blade with a tilt angle of 10 °. The stirring speed is 100 rpm.

Prepolymerization of step (1): the reaction pressure is 2.5 MPa, the reaction temperature is 10 ° C. and the reaction time is 12 minutes. The solid component as prepared in Preparation Example 1, triethyl aluminum, diisobutyldimethoxysilane (DIBDMS) are fed at a rate of 1.1 g / h, 0.088 mol / h and 0.015 mol / h, respectively; Al / Si (mole / mole) = 6.1. Propylene is fed at a rate of 10 kg / h.

Homopolymerization of propylene in the gas phase in step (2): the reaction temperature is 95 ° C., the reaction pressure is 2. -3 MPa and the reaction time

ZU is 60 minutes. The propylene is fed at a rate of 30 kg / h, the hydrogen gas is fed at a flow rate of 1.7 g / h, and the molar ratio of hydrogen / propylene gas is 0.03.

Copolymerization of propylene and ethylene gas phase in step (3): the reaction temperature is 66 ° C, the reaction pressure is 2.3 MPa, and the reaction time is 40 min. Ethylene is fed at a flow rate of 7 kg / h, propylene is fed at a flow rate of 30 kg / h and the hydrogen gas is fed at a flow rate of 0.5 g / h. The molar ratio of hydrogen / propylene gas in the reaction gas phase is 0.01, and the molar ratio of ethylene / propylene in the gaseous phase of the reaction system is 0.35. The test is carried out continuously for 48 hours, and the operation of the device is stable. In the continuous experimental process, polymers in certain amounts are taken from the reaction vessels of steps (2) and (3) and analyzed. The results are shown in Table 1.

Comparative Example 1 Example 2 is substantially repeated except that the operating conditions for the gas phase polymerization in step (2) are: the reaction temperature is 66 ° C, the reaction pressure is of 2.3 MPa and the reaction time is 60 min. Propylene is fed at a rate of 30 kg / h, the hydrogen gas is fed at a flow rate of 1.7 g / h and the molar ratio of hydrogen gas / propylene in the gas phase is 0.03 . The test is carried out continuously for 48 hours, and the operation of the device is stable. In the continuous experimental process, polymers in certain amounts are taken from the reaction vessels of steps (2) and (3) and analyzed. The results are shown in Table 1.

Table 1: Properties of Polymer Samples _______ __________

K7726 * is a K7726 impact-resistant copolymer product which is a product marketed by Yanshan Petrochemical Company. This product is obtained by peroxide degradation to increase the creep of the product, and a quantity of nucleating agent is added to improve the rigidity of the product.

Comparing Example 1 with K7726 *, it can be observed that the present invention can lead to a product having a high creep index without using the peroxide and nucleating agent, and the resulting propylene copolymer has rigidity and comparable toughness at commercialized products containing the nucleating agent. Comparing Example 2 with Comparative Example 1, it can be seen that the difference between them lies in the reaction temperature of step (2), i.e. Example 2 is 95 ° C while the polymerization temperature of Comparative Example 1 is 66 ° C as conventionally used. Example 2 can lead to an impact-resistant propylene copolymer with a creep number of 50 g / min, whereas Comparative Example 1 can only lead to a shock-resistant propylene copolymer with a creep of 14 g / min.

Therefore, the process of the present invention can produce a propylene copolymer product having a high creep number and improved stiffness and impact resistance.

Example 3: 1) Raw materials

Diisobutyldimethoxysilane is used as an external electron donor, and the other conditions are the same as in Example 1. 2) Experimental material Identical to Example 1 3) Experimental conditions

AT

Prepolymerization of step (1): the reaction pressure is 2.5 MPa, the reaction temperature is 10 ° C and the reaction time is 12 minutes. The catalyst, triethyl aluminum, and diisobutyldimethoxysilane (DIBDMS) are fed at a rate of 0.6 g / h, 0.048 mol / h (8 ml / h) and 0.0078 mol / h (2.7 ml). / h), respectively; Al / Si (mole / mole) = 6.11. Propylene is fed at a rate of 10 kg / h.

Homopolymerization of propylene gas phase in step (2): the reaction temperature is 95 ° C, the reaction pressure is 2.3 MPa and the reaction time is 60 minutes. Propylene is fed at a rate of 30 kg / h, the hydrogen gas is fed at a rate of 1.6 g / h and the molar ratio of hydrogen gas / propylene in the reaction gas phase is 0 , 03.

Copolymerization of propylene and ethylene gas phase in step (3): the reaction temperature is 66 ° C, the reaction pressure is 2.3 MPa and the reaction time is 40 min. Ethylene is fed at a flow rate of 7 kg / h, propylene is fed at a flow rate of 30 kg / h and the hydrogen gas is fed at a flow rate of 0.5 g / h. The molar ratio of hydrogen / propylene gas in the gas phase is 0.01 and the molar ratio of ethylene / propylene in the gas phase is 0.35. 4) Experimental Results The test is carried out continuously for 48 hours under the above conditions, and the operation of the equipment is stable. The polymer obtained by the reactions is analyzed and the results are presented in Table 2.

Comparative Example 2: 1) Raw materials With the exception that tetraethoxysilane is used as an external electron donor, the other conditions are the same as in Example 1.

It should be noted that the polymer obtained should have a comparable creep index to be comparable to the polymer of Example 3 in terms of mechanical properties. If Comparative Example 2 uses the same external electron donor (diisobutyldimethoxysilane) as Example 3, it may be impossible to obtain a polymer having a creep index comparable to that of Example 3, that is, that is, the creep index can not reach 55 (only about 7 as can be seen in Comparative Example 3), in the case where the reaction temperature in step (2) is 66 ° vs. Under such circumstances, tetraethoxysilane, an external electron donor more sensitive to hydrogen regulation, is used. 2) Experimental material Same as Example 3. 3) Experimental conditions

Prepolymerization of step (1): the reaction pressure is 2.5 MPa, the reaction temperature is 10 ° C and the reaction time is 12 minutes. The catalyst, triethylaluminum and tetraethoxysilane are charged at a rate of 0.5 g / H; 0.048 mole / h (8 ml / h) and 0.0078 mole / h (2.7 ml / h), respectively; Ai / Si (mole / mole) = 6.11. Propylene is fed at a rate of 10 kg / h.

Homopolymerization of propylene in the gas phase in step (2): with the exception that the reaction temperature is 66 ° C., the hydrogen gas is fed at a flow rate of 0.8 g / h and the molar ratio of hydrogen gas / propylene in the reaction gas phase is 0.015, the other conditions are the same as those in Example 3.

Copolymerization of propylene and ethylene gas phase in step (3): the reaction conditions and the operation are the same as those in Example 3. y. 4) Experimental Results The test is carried out continuously for 48 hours under the above conditions, and the operation of the equipment is stable. The polymer obtained by the reactions is analyzed and the results are presented in Table 2.

Comparative Example 3: With the exception that the polymerization temperature of propylene homopolymerization in gas phase in step (2) is 66 ° C, the other conditions are the same as those in Example 3 The polymer obtained by the reactions is analyzed and the results are presented in Table 2.

Comparative Example 4: 1) Raw materials

The main catalyst used is prepared according to Example 1 of Chinese patent CN854t) 0997, while the other conditions are the same as those in Example 3. 2) Experimental material Identical to Example 3. 3) Identical experimental conditions in Example 3. 4) Experimental Results The test is carried out continuously for 48 hours under the above conditions, and the operation of the equipment is stable. The polymer obtained by the reactions is analyzed and the results are presented in Table 2. Z \.

Table 2: Analysis results of the polymers obtained in Example 2 and Comparative Example 2. -

_ _ _ _

ά

The data in Table 2 show that: (1) Comparison of Example 3 and Comparative Example 3: With the same solid catalyst, the propylene polymer having a high creep index of the present invention can not be obtained if the stage temperature (2) is relatively low. Under the same conditions, the polymer obtained in Example 3 has a creep index of 55, whereas that of Comparative Example 3 only has a creep index of 7.6. (2) Comparison of Example 3 and Comparative Example 2: When the temperature of step (2) is relatively low, although a specific external electron donor in the catalyst is used in Comparative Example 2 so as to obtain a propylene polymer having a creep index comparable to that of Example 3, the polymer of Example 3 has mechanical properties such that rigidity and toughness are much greater than the comparative example 2, and the polymerization activity is also much higher than Comparative Example 2. (3) Comparison of Example 3 and Comparative Example 4: With a conventional catalyst in the art, the activity generally decreases at a very low multiplication rate of only 5000 if the polymerization temperature of step (2) is relatively high. However, in the present invention, after the high temperature polymerization in step (2), the copolymerization in step (3) is still of relatively high polymerization activity.

The comparative data above show that the polymerization temperature rise in step (2) can lead to a propylene polymer having both high fluidity and high rigidity. In particular, the catalyst composition of the present invention has a relatively high activity and is therefore promising for industrial applications.

Claims (15)

A process for the polymerization of propylene comprising the steps of: (1) conducting a prepolymerization of propylene or a mixture of olefins containing propylene and other α-olefin comonomer (s) in one phase gaseous or liquid phase in the presence of a Ziegler-Natta catalyst at -10 ° C to 50 ° C and 0.1 to 10.0 MPa to obtain a propylene prepolymer, the prepolymerization multiplication being controlled in the range of From 2 to 3000 g of polymer / g of catalyst, preferably from 3 to 2000 g of polymer / g of catalyst; (2) conducting homopolymerization of propylene or copolymerization of propylene and other α-olefin comonomer (s) in a gaseous phase in the presence of the propylene prepolymer as obtained in step (1) under conditions from 91 to 150 ° C, preferably from 91 to 130 ° C and more preferably from 91 to 110 ° C and from 1 to 6 MPa to obtain a propylene polymer, the polymerization time being from 0.5 to 4 hours; (3) continuing the homopolymerization or copolymerization of propylene in a gas phase or a liquid phase in the presence of the product as obtained in step (2) under conditions of 50 to 150 ° C and 1 to 6 MPa. 2. Process for the polymerization of propylene according to claim 1, characterized in that the individual steps can be carried out in a reactor for the discontinuous polymerization operation, or carried out in different reactors for the continuous polymerization operation. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that in step (1) the prepolymerization temperature is 0 to 30 ° C, preferably 10 to 25 ° C, and the prepolymerization pressure is 1.0 to 6.0 MPa, preferably 1.5 to 5.5 MPa. 4. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that said other α-olefin comonomer (s) is / are at least one α-olefin having a number of carbon atoms of from 2 to 6 but not 3. Process for the polymerization of propylene according to any of the preceding claims, characterized in that the gas phase propylene polymerization in step (2) is carried out in a horizontal reaction vessel having a horizontal stirring shaft. and a stirring rate of 10 to 150 rpm, wherein the stirring range is selected from a T-shape, a rectangle shape, an inclined blade, a door shape, a beveled shape, and any combination of these, and the reaction vessel uses a coolant to remove heat. 6. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that the polymer obtained in step (2) has an MFR flow index of 20 to 1000 g / 10 min, as measured according to IS01133 at 230 ° C and a load of 2.16 kg. 7. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that the homopolymerization or copolymerization of propylene gas phase in step (3) is carried out at a polymerization temperature of 55 to 110 ° C, and the polymer obtained in step (3) has an MFR flow index of 1 to 500 g / 10 min, as measured according to IS01133 at 230 ° C and a load of 2.16 kg. 8. A process for the polymerization of propylene according to any one of the preceding claims, characterized in that a prepolymerization of bulk propylene liquid phase is carried out at 0 to 30 ° C in step (1); homopolymerization of propylene in the gas phase is carried out at 91 to 110 ° C in step (2); and homopolymerization or copolymerization of propylene in the gas phase is continued in the presence of the product as obtained in step (2) at 55 to 110 ° C in step (3), wherein the weight ratio of the polymers reacted in steps (2) and (3) is 0.3 to 3, preferably 1.0 to 2.0. 9. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that a homopolymerization of propylene is carried out in steps (1) and (2), while a copolymerization of propylene and of Other comonomer (ε) α-olefin is performed in step (3). 10. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that the said other α-olefin comonomer (s) is / are one or more chosen among ethylene, butylene and hexylene, preferably ethylene. 11. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that in step (3), the copolymerization is carried out using ethylene in an amount of 4 to 40% by weight, preferably from 6 to 30% by weight relative to the weight of propylene homopolymer as obtained in step (2). A process for the polymerization of propylene according to any one of the preceding claims, characterized in that the Ziegler-Natta catalyst comprises a reaction product of the following components: (1) a solid catalyst component containing titanium; (2) an alkyl aluminum compound; and (3) optionally, an external electron donor component. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that the titanium-containing solid catalyst component of component (1) is a reaction product of the contacting of an alkoxy compound. magnesium, a titanium compound and an internal electron donor compound, wherein the titanium compound is at least one compound of the formula: Ti (OR) 4-nXn, wherein R is selected from an aliphatic or aromatic hydrocarbonyl group at C1-C14, X is a halogen atom, n is an integer of 0 to 4 and in the case where n is 2 or less, the existing R groups may be the same or different; the internal electron donor compound is one or more selected from alkyl esters of aliphatic and aromatic monocarboxylic acids, alkyl esters of aliphatic and aromatic polycarboxylic acids, aliphatic ethers, cycloaliphatic ethers and ketones. aliphatic, preferably selected from alkyl esters of saturated C 1 -C 4 aliphatic carboxylic acids, alkyl esters of C 7 -C 8 aromatic carboxylic acids, C 2 -C 6 aliphatic esters, C 3 cyclic ethers -C4, saturated aliphatic ketones in Cs-Cb and 1,3-diether compounds. 14. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that the alkoxy-magnesium compound is at least one chosen from compounds of formula Mg (OR1) 2-m (OR2) m, wherein R1 and R2 are the same or different and independently selected from linear or branched alkyl having 1 to 8, preferably 3 to 8 carbon atoms, and 0 <m <2. 15. Process for the polymerization of propylene according to any one of the preceding claims, characterized in that R 1 is ethyl, R 2 is (2-ethyl) hexyl, and 0.001 <m 0.5, preferably 0.001 0 m 0 , 25, more preferably 0.001 <m <0.1. 16. A propylene polymer obtained by the process for the polymerization of propylene according to any one of the preceding claims.