JPH0681772B2 - Method for producing block copolymer of propylene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a propylene block copolymer. Specifically, it relates to a method for producing a propylene block copolymer by using a specific polymerization method.

[Conventional technology]

Polypropylene is a general-purpose resin with relatively high rigidity, but its impact resistance (especially at low temperature) is poor. This problem is caused by first polymerizing propylene alone and then copolymerizing propylene and ethylene. It is known that the above can be solved by obtaining a block polymer of polypropylene having an excellent balance of impact resistance and rigidity.

On the other hand, the progress of catalysts for the polymerization of propylene has made it possible to obtain products without substantially removing the catalyst residue after the polymerization, and it is possible to obtain a block catalyst without using an inert medium by using a highly active catalyst. It has already been proposed to simply produce a block copolymer by removing the catalyst residue by obtaining the polymer (UK Patent 2,094,31
9).

[Problems to be solved by the invention]

However, a resin such as propylene, particularly a mixture of a block copolymer, etc., does not have the original physical properties of the copolymer even if the obtained polymer powder is directly molded in a molding machine, and is melted once. There is a problem that it is necessary to knead by granulating, which requires a large amount of heat energy. It is known that this can be solved by a method of finally melting a polymer using a screw reactor under a specific temperature condition (JP-A-51-37177), but the polypropylene obtained by this method is known. Has insufficient stereoregularity, the resulting polymer is inferior in physical properties, and requires a special apparatus and method.

[Means for solving problems]

The present inventor has conducted extensive studies on a method for solving the above problems and completed the present invention.

That is, the present invention is a method for producing a block copolymer of propylene by first polymerizing substantially propylene alone using a catalyst composed of a transition metal catalyst and an organometallic compound, and then copolymerizing propylene and ethylene. , (1)
Polymerization of substantially propylene alone is carried out at a temperature not higher than the melting point of polypropylene by a bulk polymerization method using propylene itself as a liquid medium or a gas phase polymerization method in which substantially no liquid medium exists, and (2) then propylene and ethylene. Polymerization of propylene is carried out under conditions such that the block copolymer is in a substantially molten state when the polymerization of the part is completed, and under the condition that a liquid medium does not substantially exist. It is a method for producing a block copolymer.

The catalyst composed of a transition metal catalyst and an organometallic compound used in the present invention has a relatively high activity per catalyst,
Moreover, there is no particular limitation as long as it is a catalyst system having high stereoregularity of the obtained polypropylene.

Examples of the transition metal catalyst include a catalyst obtained by reducing titanium tetrachloride with organic aluminum and further treating it with an electron-donating compound, and a transition metal catalyst obtained by supporting titanium halide on magnesium halide. There is no particular limitation as long as it gives regular polypropylene, but it is preferable that an electron donating compound selected from diesters of dicarboxylic acids and / or diols and esters of carboxylic acids be present in the transition metal catalyst component. In particular, very many types of supported transition metal catalysts are known, and, for example, a magnesium compound, preferably magnesium halide, the above-mentioned ester and, if necessary, another electron donating compound or a grinding aid is co-ground. A method obtained by contacting the carrier thus obtained with titanium halide, wherein a magnesium compound, preferably magnesium halide or alkoxymagnesium, is solubilized in a hydrocarbon solvent with alcohol or the like in the presence or absence of the above ester. Of the magnesium-titanium complex obtained by contacting the product with titanium halide and further subjecting it to the above-mentioned ester and / or titanium-halide contact treatment, if necessary, the presence of the above-mentioned ester of alkylmagnesium, etc. Magnesium content obtained by decomposition under or without Method of processing titanium halide body in the presence or absence of an ester mentioned above (e.g., JP 58-138710
No.) and so on.

Examples of the organometallic catalyst used in combination with these transition metal catalysts include organoaluminum compounds, organomagnesium compounds, organozinc compounds, organolithium, and the like, with organoaluminum and organomagnesium being particularly preferable,
Specifically, trialkylaluminum and dialkylaluminum halide are preferable as the organoaluminum compound, and dialkylmagnesium and diallylmagnesium are preferable as the organomagnesium compound.

Further, in the polymerization, an electron donating compound can be used together as a stereoregularity improving agent, if necessary, and many of these compounds are already known. For example, oxygen-containing organic compounds include esters, ethers, orthoesters, alkoxy silicons, and nitrogen-containing compounds include amines and amides. Particularly, aromatic carboxylic acid esters, orthoalkyl esters, orthoaryl esters, 1 to A silicon compound having 4 alkoxy groups and 3 to 0 alkyl or aryl groups is preferable, and in these compounds, an alkyl group or aryl group having 1 to 20 carbon atoms is preferable.

In the present invention, the use ratio of each of the above-mentioned components can be selected in a considerably wide range, and 0.1 to 10,000 mol of the organometallic compound and 0.01 to 1,000 mol of the electron donating compound are used per 1 mol of titanium in the transition metal component. It is common to do.

In the present invention, the block copolymer is essentially a polymerization of propylene alone by a bulk polymerization method in which propylene itself is used as a liquid medium at a temperature below the melting point of polypropylene or a gas phase polymerization method in which substantially no liquid medium is present. To do. Practically polymerizing with propylene alone means not only propylene alone but also a small amount, for example, up to about 6% ethylene,
It is also meant to include copolymerization with other olefins such as 1.

Here, the bulk polymerization method and the gas phase polymerization method are already well known, and the details are not particularly limited, and various known methods can be adopted. At this time, a tank type reactor having a complete mixing type stirrer different from the device for copolymerizing ethylene and propylene later, and a fluidized bed type reactor having or not having a stirrer are used. Usually, the polymerization temperature is room temperature to 100 ° C., preferably 50 to 90 ° C., and the polymerization pressure is normal pressure to 50 kg / cm ² .

What is important in the present invention is that the polymerization of ethylene and propylene, which is carried out subsequently, is carried out under the condition that there is substantially no liquid medium so that the block copolymer will be in a molten state at least when the polymerization of the part is completed. To polymerize. That is, the atmosphere of the part is such that the gaseous monomer is present in the gas phase part and the polymer is present in the solid phase part, and the solid phase part is
For example, in batch polymerization, the polymer exists in a molten state at least at the end of the polymerization, and in continuous polymerization, the polymer is in a molten state at least when the polymer is taken out of the continuous polymerization stagnant region. .

Unlike ordinary propylene polymerization, such polymerization is carried out under heating or adiabatic conditions, and when the ethylene / propylene copolymer accounts for a relatively large proportion of the total polymer, or when the copolymerization is relatively ethylene-free. When it is carried out under a high temperature condition, it is carried out under cooling if necessary. That is, the polymerization is not carried out at a comparatively low temperature such as usual polymerization of propylene, but is carried out so that the temperature balance is such that the polymerization is carried out at a comparatively high temperature such that the polymer is melted. At this time, it is extremely advantageous in terms of energy to balance the polymerization so that the polymerization proceeds under adiabatic conditions as much as possible. Here, the molten state is preferably stirrable and sufficiently kneadable, but when the polymer is introduced into the kneading apparatus after the polymerization reaction, it is melted and kneaded without external heating. It is good if the conditions are met.

This reaction can be carried out subsequently in a polymerization reaction apparatus in which the polymerization of substantially propylene alone is carried out, but it is preferable that the apparatus is one capable of melt-kneading, for example, a device such as a screw kneader. It is preferable to use a screw kneader provided in the cylindrical pressure-resistant container so as to equalize the pressure with the pressure-resistant container in terms of manufacturing the apparatus or carrying out the polymerization reaction.

The screw kneader may be of any shape and capacity such that the molten polymer can be stirred, and is not particularly limited, and a screw kneader of ordinary shape may be installed in the pressure vessel.

In order to carry out the polymerization reaction continuously in the present invention, the polymer obtained by substantially polymerizing propylene alone is continuously introduced into the screw kneader in the form of powder, and the polymerization of ethylene and propylene is carried out. The melted block copolymer thus obtained is taken out of the screw kneader by a conveying means such as a gear pump, if necessary, and made into pellets having an appropriate size by a cutter. At this time, it is of course possible to add a known additive such as a stabilizer to the polymer taken out from the screw kneader which is a polymerization stagnant region.

〔Example〕

 Hereinafter, the present invention will be further described with reference to examples.

Example 1 50 mg of a commercially available highly active titanium trichloride catalyst (highly active titanium trichloride catalyst TGY-24 manufactured by Marubeni Solvay Co., Ltd.) and 1 ml of diethylaluminum chloride were placed in an autoclave having an internal volume of 5, and 1.5 kg of propylene was further added. Hydrogen 4.4N
Was charged and heated to adjust the internal temperature to 70 ° C. to polymerize for 2 hours. After that, the unreacted propylene was purged, the autoclave was heated with steam to bring the internal temperature to 110 ° C., and then a mixed gas of ethylene and propylene of 1: 2 was added with stirring so as to be 40 kg / cm ² -G, Polymerization was carried out for 30 minutes while adding a mixed gas so that the pressure became constant. After completion of the polymerization, the autoclave was disassembled and the polymer was taken out to obtain 650 g of a melted copolymer.

Intrinsic viscosity (henceforth, indicated by η) measured with a 135 ° C tetralin solution of the polymer is 2.85, and ethylene content is 28 wt.
%Met.

Example 2 i) Synthesis of Transition Metal Catalyst A To a round bottom flask having an internal volume of 2 was added 700 ml of purified kerosene, 10 g of magnesium chloride and 37 g of 2-ethylexanol,
It was completely dissolved by stirring at 100 ° C for 24 hours. Diisobutyl phthalate (10 ml) was added thereto, and the mixture was stirred and then slowly added dropwise to the titanium tetrachloride 2 kept at 0 ° C. in a round bottom flask at 5 with stirring. Thereafter, the temperature was slowly raised and the treatment was carried out at 100 ° C. for 1 hour. Then, only the obtained solid content was transferred to a 200 ml round bottom flask, 100 ml of titanium tetrachloride was further added, and 100
The mixture was stirred at 0 ° C., and finally the solid content was washed 10 times with n-heptane to obtain a transition metal catalyst A.

This transition metal catalyst A contained 3.5 wt% titanium and 5.2 wt% diisobutyl phthalate.

ii) Polymerization reaction 1 Under an atmosphere of nitrogen, 1 g of transition metal catalyst A, 3.0 ml of triethylaluminum and 1.5 ml of trimethoxyphenylsilane were placed in an autoclave having an internal volume of 500, and then propylene 1 was added.
00 kg was charged, 150 N of hydrogen was further added, and polymerization was carried out at 65 ° C. for 1 hour.

After completion of the reaction, unreacted propylene was purged to obtain a propylene homopolymer. One part was sampled and the ratio of η and the boiling n-heptane extraction residue (boiled n-heptane using a Soxhlet extractor for 6 hours) was measured and found to be 1.58 and 98.2%, respectively.

iii) Polymerization reaction 2 This active polypropylene powder was continuously charged into a device having the shape shown in FIG. 1 at about 1 kg / hr under a nitrogen atmosphere.
The gas phase part of this equipment was pressurized to 40kg / cm ² -G with a mixed gas of ethylene and propylene (1: 2), and the kneader part was heated to 120 ° C with steam, and the residence in this kneader part The time was 40 minutes, and the polymer was melted (temperature 195 ° C.) at the take-out port. This polymer was mixed with a phenolic stabilizer (1/1000 weight ratio to the polymer) by a gear pump and taken out at about 1.4 kg / hr.

The ethylene content of the obtained polymer was 26 wt% and the thickness
Create a 2mm injection sheet, melt flow index (MI, ASTM D-1238, measurement temperature 230 ℃), flexural rigidity (ASTM D-747-63, measurement temperature 20 ℃), Izod (notched) impact strength ( ASTM D-256-56, measurement temperature-1
0 ℃ and -20 ℃) and DuPont impact strength (JIS K-6718,
Measurement temperature -10 ℃ and -20 ℃) was measured, respectively, 1.5g / 10 minutes, 9350kg / cm ² , 30kg / cm ² (-10 ℃) and 1
1.5kg / cm ² (-20 ℃), non-destructive (-10 ℃) and 115kg / cm ²
It was φ (−20 ° C.).

〔The invention's effect〕

By carrying out the method of the present invention, it becomes possible to easily produce a propylene block copolymer with extremely high energy efficiency, which is extremely valuable industrially.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of an apparatus suitable for carrying out the method of the present invention, and FIG. 2 is a sectional view of a pressure-proof cylindrical portion.
In the figure, 1 and 2 are motors, 3 is a gear pump, and 4
Is an active polymer hopper, 5 is a feeder, 6 is an inlet for a monomer, 7 is a screw kneader, 10 is a screw kneader, 11 is an outer shell of the kneader, and 12 is a heating or cooling jacket.

Claims (2)

[Claims] 1. A method for producing a block copolymer of propylene by first polymerizing substantially with propylene alone using a catalyst comprising a transition metal catalyst and an organometallic compound, and then copolymerizing propylene and ethylene. (1) Polymerization of propylene alone is carried out at a temperature not higher than the melting point of polypropylene by a bulk polymerization method using propylene itself as a liquid medium or a gas phase polymerization method in which substantially no liquid medium exists, and (2) Polymerization of propylene and ethylene is carried out under conditions such that the block copolymer is in a substantially melted state at least when the polymerization of the part is completed, and under the condition that there is substantially no liquid medium. And a method for producing a block copolymer of propylene. 2. The block copolymer of propylene according to claim 1, wherein the polymerization of propylene and ethylene is carried out in a cylindrical pressure vessel by a screw kneader installed so as to equalize the pressure with the pressure vessel. Manufacturing method.