JPH1025323A - Production of alpha-olefin block copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing an α-olefin block copolymer good in physical properties. SOLUTION: This method for producing an α-olefin block copolymer comprises polymerizing an α-olefin in the presence of an organic aluminum compound, a transition metal catalyst component comprising a magnesium dihalide, a phthalate diester and a tetravalent titanium compound having at least one halogen, and an alkoxyalkysilane in an amount of 5-90 moles per mole of the titanium contained in the transition metal catalyst component, adding an alkoxylalkylsilane in an amount of 0.5-50 moles per mole of the titanium contained in the transition metal catalyst component to the polymerization product, and subsequently copolymerizing ethylene with the α-olefin.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an α-olefin block copolymer. More specifically, the present invention relates to a method for producing a block copolymer having good physical properties and excellent moldability using a specific catalyst. 2. Description of the Related Art Polyolefins have been widely produced by polymerizing olefins using a catalyst comprising a transition metal compound and an organometallic compound. Among them, in order to improve the impact resistance of polyolefins. First, an α-olefin is polymerized, and then ethylene and an α-olefin are polymerized to produce a block copolymer. At this time, reducing the molecular weight of the α-olefin polymer obtained in the preceding step and increasing the molecular weight of the copolymerized part are widely and commonly used as a method for maintaining a good balance between moldability and physical properties. For this purpose, a large amount of hydrogen, which is a molecular weight regulator, is usually added in the first stage to produce a low-molecular-weight poly-α-olefin, which is then purged with hydrogen or reacted with the olefin under conditions that increase the molecular weight. Manufacture of a polymer is performed. [0004] However, a method for adding and removing a large amount of hydrogen (JP-A-2-30580).
The method 9) consumes unnecessary energy and also consumes extra hydrogen, and is complicated, and has a problem in reproducibility of physical properties of the obtained block copolymer with poor controllability. On the other hand, the method of starting polymerization with a specific alkoxysilane first and then adding a different kind of alkoxysilane to continue the polymerization (Japanese Patent Application Laid-Open No. 6-220116) has a problem that the effect is to some extent but not sufficient. There is a need for the development of better methods. The present inventors have intensively studied a method for producing a block copolymer having excellent fluidity and a good balance of physical properties by solving the above problems and completed the present invention. . That is, the present invention uses a catalyst comprising a transition metal catalyst component comprising a magnesium halide, a diester of phthalic acid and a tetravalent titanium compound having at least one halogen, and a catalyst comprising an organoaluminum compound and an alkoxysilane compound. In a method of producing an α-olefin block copolymer by polymerizing an α-olefin and then copolymerizing ethylene and an α-olefin, first, an alkoxyalkylsilane is added to the transition metal catalyst component in an amount of 5 to 5 mol per titanium. The polymerization of α-olefin is carried out using 90 mole times, and then alkoxycycloalkylsilane is added in an amount of 0.5 to 5 per mole of titanium in the transition metal catalyst component.
A method for producing an α-olefin block copolymer, characterized in that ethylene and an α-olefin are copolymerized by adding 0 mol times. BEST MODE FOR CARRYING OUT THE INVENTION The magnesium halide used for producing the transition metal catalyst component of the present invention is magnesium chloride, magnesium bromide, a complex thereof with an ether or a monoester, or a mixture of magnesium chloride and odor. A eutectic of magnesium oxide can be used. As the diester of phthalic acid, an ester of phthalic acid and an alcohol having 1 to 12 carbon atoms is preferably used, and dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dibutyl phthalate, dioctyl phthalate, didecyl phthalate, phthalate In addition to diphenyl acid, dibenzyl phthalate, di-2-ethylhexyl phthalate and the like, diesters such as butylbenzyl phthalate and ethylhexyl phthalate in which two alcohols forming an ester bond are different can be used. As the tetravalent titanium compound having at least one halogen which is preferably used in the present invention, chlorine is preferably exemplified as the halogen, and a compound in which a part of the halogen is changed to an alkoxy group can also be used. Particularly preferably, titanium tetrachloride is used. In the present invention, the method for producing a transition metal catalyst component comprising a magnesium halide, a diester of phthalic acid and a tetravalent titanium compound having at least one halogen is not particularly limited, and all components are co-ground. If necessary, a heat treatment with a hydrocarbon compound or a halogenated hydrocarbon compound, solubilizing a magnesium halide with an electron-donating compound such as an alcohol in an inert solvent, and in the presence or absence of a diester of phthalic acid The carrier can be produced by preliminarily treating with a phthalic acid diester on a carrier obtained by precipitating by contacting with a titanium halide or the like, or by simultaneously supporting the titanium halide. Here, the titanium halide may be used by forming a complex with a diester of phthalic acid in advance. The co-pulverization is performed by a usual vibration mill or ball mill, and the pulverization time is several hours to several hundred hours, and the pulverization temperature is −70 to 100 ° C. Preferably, the grinding time is several hours to several tens of hours, and the grinding temperature is -10.
Performed at ~ 50 ° C. Here, the molar ratio of the phthalic acid diester to the titanium halide is 0.1: 1 to 1: 0.1, preferably 0.3: 1 to 1: 0.3. If it exceeds this range, the activity when polymerizing with the catalyst and the stereoregularity of the resulting polymer are not sufficient. The ratio of titanium halide to magnesium halide is preferably about 1: 0.001 to 1: 0.5 by weight. It is also possible to use a carrier inert to the catalyst system in combination, and in addition to inorganic substances such as silica and alumina, polymer compounds such as polyethylene, polypropylene and polystyrene can be used. Examples of the hydrocarbon compound or halogenated hydrocarbon compound include a hydrocarbon compound having 1 to 12 carbon atoms or a compound in which 1 to all of hydrogen is substituted with chlorine, bromine or iodine. The heating temperature is generally from 50 to 150 ° C, and a particularly preferred temperature is from 70 to 130 ° C. Use ratio of hydrocarbon compound to co-ground product is 1/1
Generally, it is carried out at a ratio of 1/100 wt / vol. What is important in the present invention is that at least two types of alkoxysilane compounds having a specific structure are used in a specific method during polymerization. One of the alkoxysilane compounds used here is represented by the following general formula (Chemical Formula 1)
Wherein R is an alkyl group having 1 to 12 carbon atoms, and R ′ is an alkyl group having 1 to 12 carbon atoms.
12 straight-chain or branched alkyl groups, n is 1 to 2
Is an alkoxyalkylsilane represented by
Preferably R is an n-alkyl group. R _n Si (0R ′) _4-n Another component is represented by the following general formula (Formula 2)
In the formula, at least one of R ″ is a cycloalkyl group having 4 to 12 carbon atoms, and the other may be a linear or branched alkyl group having 1 to 12 carbon atoms. R ′ ″ is a linear or branched alkyl group having 1 to 12 carbon atoms, and n is 1
(An integer of ~ 3) alkoxycycloalkylsilane. [0017] [Chemical Formula 2] _{R '' n Si (OR '} '') 4-n [0018] Specifically, R, R a', R '', R ''' is,
A methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and at least one of R '' is a cyclobutyl group, a cyclopentyl group, a cyclohexyl group,
And a norbornyl group. Here, two kinds of alkoxysilane compounds are used in combination by first using the alkoxyalkylsilane represented by the above general formula (Chemical Formula 1), performing desired polymerization, and then converting the compound by the above general formula (Chemical Formula 2). It is necessary to use the alkoxycycloalkylsilane to be used. The use amount of the two alkoxysilane compounds per mole of titanium in the transition metal catalyst component is 5 to 90 mole times and 0.5 to 50 mole times, respectively. Also, the amount of the alkoxycycloalkylsilane used is 1/100 of the amount of the alkoxyalkylsilane used.
-10/1, preferably about 1 / 20-2 / 1.
When the amount of the alkoxycycloalkylsilane used is 1/100 or less of the amount of the alkoxyalkylsilane, the physical properties of the block copolymer obtained when the subsequent polymerization is performed under the same conditions are poor, and the physical properties are good. Therefore, it is necessary to remove a large amount of hydrogen during the polymerization in the subsequent stage. On the other hand, if the ratio is 10/1 or more, the amount of the alkoxysilane compound to be used is unnecessarily increased, which is not effective. It is important to use a relatively large amount of alkoxyalkylsilane in the first stage and a relatively small amount of alkoxycycloalkylsilane in the second stage.
When a relatively small amount of alkoxyalkylsilane is used in the first stage and a relatively large amount of alkoxycycloalkylsilane is used in the second stage, there is a problem in the stereoregularity of the obtained polymer. When the alkoxyalkylsilane is used, the effect of expanding the molecular weight distribution is small. Here, the alkoxycycloalkylsilane is generally added at the start of the copolymerization of ethylene and α-olefin in the latter stage, but usually after the homopolymerization of α-olefin in the former stage is almost completed. It can be added when about 80% of the polymerization in the first stage is completed. In the present invention, the organoaluminum compound is preferably a trialkylaluminum such as trimethylaluminum, triethylaluminum, tripropylaluminum or tributylaluminum, and one or two hydrocarbon residues thereof are substituted with chlorine or bromine. Examples are alkyl aluminum halides. Organoaluminum compound for titanium in transition metal catalyst component and the above alkoxysilane compound
1: 1: 1 (using the sum of both components)
１ ： 1: 100: 1000 molar ratio, usually 1: 1: 1-1: 50:
200 molar ratio. In the present invention, the α-olefin includes
Examples thereof include α-olefins having 3 to 12 carbon atoms, specifically, propylene, butene-1, pentene-1, hexene-1,
Heptene-1, octene-1, 4-methylpentene-1 and the like are exemplified. The homopolymerization in the first stage means homopolymerization of these α-olefins or copolymerization with a small amount of another α-olefin or ethylene. The α-olefin is preferably propylene. In addition, ethylene and α-
The term “olefin copolymerization” refers to polymerization performed by charging ethylene and α-olefin under conditions such that the polymerization ratio of ethylene and α-olefin is 20/80 to 80/20. It is general that the polymerization ratio of the first-stage α-olefin homopolymerization and the second-stage copolymerization of ethene and α-olefin is about 95/5 to 40/60. In the present invention, the polymerization method of the α-olefin is not particularly limited, and various known methods can be employed.
Any of a solvent polymerization method using an inert hydrocarbon as a medium, a bulk polymerization method using a liquid α-olefin as a medium, and a gas-phase polymerization method containing substantially no liquid medium can be employed. In general, the polymerization is carried out at a temperature of ordinary temperature to 150 ° C. and a pressure of ordinary pressure to 100 kg / cm ² , and homopolymerization of α-olefin or copolymerization of ethylene and α-olefin in the latter stage is carried out. Will be When a block copolymer is continuously produced by utilizing the present invention, two or more types of reaction tanks are connected to each other, and the first-stage polymerization is performed in at least two or more tanks. −
, Especially ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol or a compound whose terminal is linked to a hydrocarbon residue by an ether bond or an ester bond in an amount of 1 to 100 moles per mole of titanium in the transition metal catalyst component. By adding it, a block copolymer having good physical properties can be obtained. The present invention will be further described with reference to the following examples. Example 1 A vibrating mill equipped with four crushing pots having a capacity of 4 liters and containing 9 kg of steel balls having a diameter of 12 mm is prepared. 300 g of magnesium chloride, 75 ml of diisobutyl phthalate, and 60 ml of titanium tetrachloride were added to each pot in a nitrogen atmosphere, and pulverized for 40 hours. 10 g of the above co-ground product was placed in a 200 ml flask, 60 ml of toluene was added, and the mixture was stirred at 114 ° C. for 30 minutes, and then allowed to stand to remove the supernatant. Then 100 ml of n-heptane
The solid content was washed three times at 20 ° C. and further dispersed in 100 ml of n-heptane to obtain a transition metal catalyst component slurry. The obtained transition metal catalyst component contained 1.9 wt% of titanium and 14.2 wt% of diisobutyl phthalate. An autoclave having an inner volume of 5 liters and sufficiently dried and replaced with nitrogen was prepared, and 0.1 g of triethylaluminum diluted with 100 ml of heptane (148 g / titanium) was used.
Mol), 0.05 g of n-propyltrimethoxysilane (51 mol per titanium), 15 mg of the above transition metal catalyst component (0.006 mmol as titanium), 1.5 kg of propylene, hydrogen
1.6N liter was added and polymerization was carried out at 70 ° C for 60 minutes. 0.02 g of cyclohexylmethyldimethoxysilane (per titanium)
16 mol), and then the temperature was lowered to 50 ° C, and ethylene was added at 4 kg / cm.
^2- G was added and polymerization was carried out for another 30 minutes. After polymerization, unreacted propylene was purged, dried at 80 ° C. for 8 hours, and weighed to 660 g.
A propylene block copolymer was obtained. The intrinsic viscosity number (hereinafter abbreviated as [η]) of the copolymer is 1.80 dl / g,
The ethylene content was 7.8 wt%. A phenolic stabilizer was added to this polypropylene, and the following physical properties were measured using a molded article having a thickness of 2 mm obtained by press molding at 230 ° C., and the tensile yield strength (kg / cm ² , ASTM D638 (23 ° C.)) is 320 kg / cm ^2, Izod (notched) impact strength (kg · cm / cm, ASTM D256-
56 (23 ° C., −10 ° C.) were 16.0 and 5.2 kg · cm / cm, respectively. COMPARATIVE EXAMPLE 1 Polymerization was conducted in the same manner as in Example 1 except that cyclohexylmethyldimethoxysilane was used.
680 g of a propylene block copolymer having dl / g and an ethylene content of 7.8 wt% was obtained. Physical properties of the obtained polymer are as follows: tensile yield strength is 305 kg / cm ² , Izod (with notch) impact strength
(23 ° C, -10 ° C) were 13.0 and 3.5 kg · cm / cm, respectively. Comparative Example 2 The procedure of Example 1 was repeated, except that 0.05 g of cyclohexylmethyldimethoxysilane was used instead of 0.05 g of n-propyltrimethoxysilane, and the amount of hydrogen used was changed to 3N liter. 620 g of a propylene block copolymer having dl / g and an ethylene content of 7.2 wt% was obtained. The physical properties of the obtained polymer are as follows: tensile yield strength is 310 kg / cm ² , Izod
(Notched) Impact strength (23 ° C, -10 ° C) is 1
They were 3.5 and 3.8 kg · cm / cm 2. Comparative Example 3 The procedure of Comparative Example 1 was repeated except that the amount of hydrogen added was changed to 1.2 Nl.
660 g of a wt% propylene block copolymer was obtained. Regarding the physical properties of the obtained polymer, the tensile yield strength was 325 kg / cm ² , and the Izod (notched) impact strength (23 ° C., −10 ° C.) was 14.0 and 3.5 kg · cm / cm, respectively. Example 2 After homopolymerization of propylene was carried out for 50 minutes, 0.02 g of cyclohexylmethyldimethoxysilane was charged, and homopolymerization of propylene was carried out for another 10 minutes. Example 1
When [η] was 1.85 dl / g and the ethylene content was 9.9 wt%, a block copolymer of propylene was 640 g.
I got The physical properties of the obtained polymer are as follows: tensile yield strength is 330k
g / cm ² , Izod (with notch) Impact strength (23 ° C, −
10 ° C.) were 16.0 and 5.8 kg · cm / cm 2 respectively. By carrying out the method of the present invention, a block copolymer of α-olefin having good physical properties can be easily produced, which is industrially valuable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart for helping the understanding of the present invention.

Claims (1)

Claims: 1. A transition metal catalyst component comprising a magnesium halide, a diester of phthalic acid and a tetravalent titanium compound having at least one halogen, and a catalyst comprising an organoaluminum compound and an alkoxysilane compound. First polymerizes the α-olefin and then ethylene and α
In the method for producing an α-olefin block copolymer by copolymerizing an olefin, the polymerization of the α-olefin is carried out by first using an alkoxyalkylsilane in an amount of 5 to 90 mol per mol of titanium in the transition metal catalyst component. Block copolymerization of an α-olefin, wherein an alkoxycycloalkylsilane is added in an amount of 0.5 to 50 mole times per mole of titanium in the transition metal catalyst component to copolymerize ethylene and an α-olefin. Manufacturing method of coalescence. 2. The amount of alkoxycycloalkylsilane used is 1/20 to 2/20 of the amount of alkoxyalkylsilane used.
The method of claim 1, wherein