JPS62232411A - Production of propylene copolymer - Google Patents

Abstract

PURPOSE:To produce a propylene copolymer which is improved in transparency and can give a molding free of surface clouding and stickiness, by bulk- polymerizing propylene and ethylene in the presence of an aromatic hydrocarbon compound by using the propylene itself as a liquid medium and using modified titanium trichloride and a specified dialkylauminum halide. CONSTITUTION:A propylene copolymer is produced by bulk-polymerizing propylene and ethylene by using the propylene itself as a medium and using titanium trichloride modified with an oxygen-containing organic compound and a dialkylaluminum halide. Said copolymerization is performed by using a dialkylaluminum halide having a halide to aluminum atomic ratio of 0.90-1.10 in the presence of 1-20vol%, based on the entire volume of the liquid medium, 6-10 C aromatic hydrocarbon compound so that ethylene and/or its mixture with a 4-6 C alpha-olefin may account for 10wt% based on the total copolymer. The copolymer slurry is washed countercurrently with propylene to obtain a propylene copolymer of excellent transparency.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for producing copolymers of propylene. Specifically, the present invention relates to a method for producing a propylene copolymer that has excellent transparency, does not have a cloudy or sticky surface when molded, and has excellent heat sealability.

Conventional technology Propylene crystalline copolymers with excellent low-temperature impact resistance, rigidity, and transparency are widely used as blow grades or sheet grades for food containers, film grades for food packaging, and laminated grades. For example, the manufacturing method is described in Japanese Patent Publication No. 43-11230 and Special Publication No. 43-11230.
4-4992 and JP-A-53-35788 are known. In order to improve the low-temperature impact resistance and heat sealability of a propylene copolymer, it is possible to increase the ethylene content in the propylene copolymer, or to use ethylene and higher α-olefins such as butene-1 (especially Kaisho 49-35
487, JP-A-51-79195, JP-A-52-165
88, JP-A-54-26891) is known, but when the content of higher α-olefins such as ethylene is increased, more olefins become soluble in the polymerization medium. There are known methods for selectively dissolving and removing only the components that impair the appearance of the molded product (for example, JP-A-57-149309, JP-A-58-
136607, JP-A-59-129209, etc.).

Problems to be Solved by the Invention However, even with the above method, it is difficult to obtain propylene obtained by using a high boiling point inert hydrocarbon to remove a large amount of the portion soluble in the polymerization medium (i.e., a method with poor product yield). Compared to copolymers, it has poor appearance, transparency, etc., and also has a high melting point and poor heat sealability.

Means for Solving the Problems The present inventors have completed the present invention by intensively studying methods for solving the above problems.

That is, the present invention provides a method for producing a propylene copolymer by a bulk polymerization method using titanium trichloride modified with an oxygen-containing organic compound and a dialkyl aluminum halide, using propylene itself as a medium. 1-
In the presence of 20% by volume of an aromatic hydrocarbon compound having 6 to 10 carbon atoms, a dialkyl aluminum halide with an atomic ratio of halide to aluminum of 0.90 to 1.10 is used to react with ethylene and/or ethylene. Carbon number 4
Propylene with excellent transparency characterized by copolymerizing so that the sum of α-olefins in ~6 is 15% by weight or less in the total copolymer, and then washing the copolymer slurry in countercurrent with propylene. This is a method for producing a copolymer.

In the present invention, titanium trichloride modified with an oxygen-containing organic compound is produced as follows. That is, a method of co-pulverizing titanium trichloride obtained by reducing titanium tetrachloride with aluminum, hydrogen, or organoaluminium, or a eutectic of titanium trichloride and aluminum chloride with an oxygen-containing organic compound, or a contact treatment with an oxygen-containing organic compound. There are methods of washing with a hydrocarbon compound, and any method that includes a step of contacting with an oxygen-containing organic compound in the step of producing a titanium trichloride catalyst is sufficient. Examples of oxygen-containing organic compounds include ethers, esters, orthoesters, alkoxy silicones, phosphoric esters, ketones, aldehyde carboxylic acids, and carboxylic anhydrides.

As a specific manufacturing method, for example, Japanese Patent Publication No. 43-10065
, a catalyst obtained by grinding titanium trichloride or aluminum chloride reduced with metallic aluminum and then adding ether, ketone, or ester and co-pulverizing the catalyst as shown in Japanese Patent Publication No. 43-15620, or a catalyst obtained by co-pulverizing titanium trichloride reduced with metallic aluminum, or co-pulverizing with the addition of ether, ketone, or ester. -23591
, a catalyst further washed with an inert hydrocarbon as shown in Japanese Patent Publication No. 49-2021. Alternatively, there is a method in which the above eutectic and organoaluminum are co-pulverized in the presence of an olefin, then contacted with ether, further treated with titanium tetrachloride, and then washed with an inert hydrocarbon to obtain a titanium trichloride catalyst. Furthermore, titanium trichloride disclosed in JP-A No. 47-34478 is obtained by reducing titanium tetrachloride with organoaluminium, contacting it with ether, treating it with titanium tetrachloride and/or iodine, and washing it. can be mentioned.

AI (CJs) is a dialkyl aluminum halide.
)zcI 5Al(CJs)Br1Al(CJs)I
, AI(C3Ht)zcl, AI(CsHy) Jr
, AI(CJt)zl, AI(C4■q)zcl
, AI (C4119) tBr , AI (C4+
19) AI (CJs) among tl etc.
zcl is preferably used.

What is important in the present invention is that the dialkyl aluminum halide has a halide to aluminum ratio of 0.9.
0-1.10 atomic ratio, preferably 0.92-1.08
It is particularly preferable to use a Morino of 0.94 to 1.04.

If the ratio of halide to aluminum is out of the above range, the activity per titanium trichloride catalyst will be insufficient, and the resulting propylene copolymer will have a sticky or sticky surface when molded, which is undesirable.

In the present invention, stereoregularity improvers such as ethylene glycol, alkyl ethers, esters, orthoesters, and phosphoric esters can also be used in combination with the above catalyst system.

In the present invention, as the aromatic hydrocarbon compound used during polymerization, benzene, toluene, xylene, ethylbenzene, cumene, diisopropylbenzene, trimethylbenzene, tetramethylbenzene, butylbenzene, etc. can be used, and in particular toluene, xylene, Ethylbenzene can be preferably used.

In the present invention, propylene is polymerized using propylene itself as a liquid medium, and in the presence of the above-mentioned aromatic hydrocarbon compound, and the polymerization temperature is room temperature to 80°C, preferably 40 to 70°C, and below 40°C. Not only is the catalytic activity low, but it is difficult to remove the heat of polymerization when carried out on an industrial scale.

Moreover, if the temperature is 75° C. or higher, the bulk density of the obtained copolymer decreases, which is not preferable. Polymerization pressure depends on the type of aromatic hydrocarbon,
amount, ethylene concentration, amount of hydrogen used as a molecular weight regulator, and polymerization temperature.

The total amount of ethylene and/or ethylene and α-olefin having 4 to 6 carbon atoms in the copolymer obtained in the present invention is 10% by weight or less, preferably 8% by weight or less. 10
If the proportion by weight is exceeded, the resulting propylene copolymer will have poor rigidity, resulting in a sticky or cloudy surface when formed into a film, etc., and during polymerization, the bulk specific gravity of the polymer will decrease and the viscosity of the slurry will increase. This causes problems such as difficulty in removing polymerization heat.

What is important in the present invention is to produce the propylene copolymer under conditions where the aromatic hydrocarbon in the liquid polymerization medium is present in an amount of 1 to 20% by volume. If the amount of aromatic hydrocarbon is less than 20% by volume, the effect of improving the appearance, stickiness, and transparency of the molded product will not be sufficient, and even if it is more than 20% by volume, no further improvement will occur and the activity will simply decrease. Only. The preferred range is 3 to 10% by volume.

In the present invention, the copolymer slurry obtained by the above operation is then countercurrently washed with propylene.

It is more preferable to deactivate the catalyst with alcohol or epoxide to solubilize the catalyst residue prior to countercurrent washing. This step may be carried out at 40 to 70°C.

The propylene used for Lj flow cleaning may contain small amounts of ethylene, ethane, propane, etc. When containing hydrocarbon compounds having 5 or more carbon atoms, the amount of these hydrocarbons is preferably 10% by weight or less. If the weight exceeds 10 weight, even if the medium is removed from the slurry by evaporation, there will be a large amount of volatile matter in the resulting powder, which will require a lengthy drying process, and in some cases, the polymer will dissolve in the medium during heating. The powder will form into clumps, leading to blockage of transportation lines.

The countercurrent cleaning tower may have a normal shape (there is no particular limitation) as long as it has a slurry inlet and a cleaning liquid outlet at the top and a cleaning liquid inlet and a cleaning agent slurry outlet at the bottom.

Effect The reason why the appearance and stickiness of molded products are improved by carrying out the method of the present invention is that the catalyst is composed of titanium trichloride modified with an oxygen-containing organic compound and dialkyl aluminum halide having a specific halogen/aluminum atomic ratio. The propylene-ethylene random copolymer obtained in
It is presumed that this is because the portion that adversely affects the above-mentioned appearance stickiness (probably a low molecular weight, low stereoregular polymer) is small or is easily removed by the countercurrent washing tower.

The reason why the transparency is greatly improved is not clear as there is no tendency for the molecular weight distribution to be narrow, but for some reason, a copolymer with good transparency can be obtained by combining the above catalyst system and an aromatic hydrocarbon. It seems that there is.

Example The present invention will be specifically explained below with reference to Examples.

In Examples and Comparative Examples, the physical properties of the copolymer were determined by using a phenolic stabilizer at a weight ratio of 20/10,000, calcium stearate at a weight ratio of 10/10,000, and a lubricant at a weight ratio of 20/10,000.
After adding at a weight ratio of 10,000 and granulating at 250°C, a T-die film with a thickness of 30 μm and a width of 25 cm was prepared at 240°C and evaluated. Measurement of each physical property is as follows; Intrinsic viscosity = Measured with tetralene solution at 135°C Haze (χ)
: ASTM-1003-53 Bum Rod (2): Calculated as a percentage of the adhering area after stacking two films together and placing a 2 kg weight on it and keeping it at 50°C for 24 hours Young's modulus (Kg/mm): 20 mm x 220 mm
Tensile strength (Kg/ad): ASTM D882-6
4 impact (Kgcm/+*m): Calculated from the impact energy when a spherical weight is applied to a film of 10IIIm x 10a1 at 5°C to break it. Embossment: Visually inspected after holding the film at 50°C for 24 hours. Determined melting point and crystallization temperature (abbreviated as T1 and Tc, respectively)>
: Measured using D, S, and C at a temperature rising and cooling rate of 10° C./win.

Example 1 Production of titanium trichloride catalyst A. In a grinding pot with an internal volume of 900 m1 containing 2.3 kg of steel balls with a diameter of 12 ml, 60 g of titanium trichloride (TAC-141) manufactured by Toho Titanium ■, and 4 Peng of diethyl aluminum chloride were added. ] was added and 1 g of ethylene was charged while co-pulverizing.

The operation of taking out the co-pulverized material was repeated three times. 100 g of the co-pulverized material obtained was dispersed in 800 ml of n-hebutane, then isoamyl ether 2241 was added over 20 minutes, and then 480 ml of titanium tetrachloride was added over 30 minutes.

Thereafter, the temperature was raised to 60°C, and the mixture was treated for 2 hours with stirring, and then washed five times with n-hebutane at room temperature and once at 70°C. (Catalyst A) B, 5j! 11 n-hexane and 250 nl of titanium tetrachloride were placed in a round-bottomed flask, and 300 ml of diethylaluminum chloride (diluted in 900 ml of n-hexane) was added dropwise with stirring at -5°C over 5 hours. Then at -1℃
．． After keeping it under stirring for 5 hours, wash the obtained titanium trichloride with n-hexane 5 times (1500 ml each time)
.

N-hexane 3000o+ was added to the obtained solid titanium trichloride.
1 was added and kept at 65°C for 4 hours with stirring, then 1500
Washed twice with ml of n-hexane. Next, 44 ml of isoamyl ether diluted in 1500 ml of n-hexane was added and kept at 30 DEG C. for 1 hour, and then the solid titanium trichloride was washed 5 times, once with 1500+1 n-hexane.

Next, a solution obtained by diluting 60 ml of titanium tetrachloride in 10,100 O n-hexane was added and treated at 65°C for 2 hours, and then washed 5 times with 1500 ml of n-hexane once to obtain a titanium trichloride catalyst (catalyst B). .

Commercially available titanium trichloride catalyst (manufactured by Toho Titanium ■, TAC-3-21) obtained through a process of contacting a C1 titanium trichloride aluminum chloride eutectic with diethyl ether.
(Catalyst C) was washed (3 times) with 31 g of toluene per 500 g.

Example 1 25 kg of propylene, 11.7 kg of butene, and 31 kg of toluene are charged into a jacketed 100 F autoclave which has been thoroughly dried, purged with nitrogen, and further purged with propylene. On the other hand, 1! 500m of n-hebutane in a flask of
1, diethylaluminum chloride (chlorine/aluminum ratio 1.01) 15al Catalyst B1 obtained in Example 1.
5 g were mixed and press-fitted into the above 100 J autoclave. A predetermined amount of hydrogen and ethylene were charged, and then hot water was passed through the jacket to maintain the internal temperature at 60°C, gas phase hydrogen concentration at 9.0χ, gas phase concentration of ethylene at 2.0χ, and butene at 14.5χ. Ethylene and butene-1 were charged, and polymerization was continued for 3 hours while charging propylene at a rate of 5 kg/h. After 3 hours had passed, 50n+1 ethylene glycol monoisopropyl ether was added and stirred at 60°C for 30 minutes. The resulting slurry has an inner diameter of 10 cm at the fine part.
, the slurry was placed at the top of a countercurrent cleaning tower with an inner diameter of 30 cm in the thick part at the top, a length of 10 m in the fine part, and a length of 2 m in the thick part at the top. 5%, ethylene 1%, butene-15%
A cleaning solution with a composition of 4% toluene was introduced at a rate of 40 kg/h, and the cleaning solution was poured from above at 44 kg/h, and the washed slurry was taken out from the bottom at a rate of 26 kg/h. The slurry taken out had an inner diameter of 374 inches and a length of 60 m. It was discharged through a double pipe into a cyclone maintained at atmospheric pressure. Double pipe is I
It was heated through Kg/G of steam. The powder taken out from the cyclone was kept at 50℃ and 5Qmml (g
About 13 g of polymer was obtained after drying for 10 hours. 0.5 Kg of polymer was recovered from the washing liquid from the top of the unidirectional flow washing tower. Therefore, the yield of product powder based on total polymer was about 96%. The obtained powder was granulated and film-formed under the conditions described above, and its physical properties were measured.

Examples 2 to 3 The initially charged toluene was changed to xylene and chlorine/
Diethylaluminum chloride with an aluminum ratio of 1.04 was used (Example 2), and diethylaluminum chloride with a chlorine/aluminum ratio of 0.95 was used, and the ethylene concentration in the gas phase was 1.5χ, butene-1
The procedure was the same as in Example 1 except that the concentration was 5.0χ (Example 3). The results are shown in the table.

Examples 4 to 5 As a catalyst, the same molar chlorine/aluminum ratio as catalyst A was used.
02 dipropyl aluminum chloride was used (Example 4), and catalyst C was used instead of catalyst B (Example 5)
Other conditions were the same as in Example 1. The results are shown in the table.

Comparative Examples 1 to 3 n-hebutane 2,7I instead of toluene 3β! , toluene was set to 0.31 (Comparative Example 1), and the chlorine/aluminum ratio was set to 0.89 as diethylaluminum chloride (Comparative Example 2) toluene 0.3 was used instead of 3Il of toluene.
j! In addition, diethylaluminium chloride with a chlorine/aluminum ratio of 1.2 was used (Comparative Example 3) The rest was the same as in Example 1. The results are shown in the table.

Comparative Example 4 As a comparative example using a catalyst supported on magnesium chloride, a copolymerization reaction similar to that in Example 1 was carried out using the same catalyst system as in Example 1 of JP-A-59-129205. The results are shown in the table.

,/ /′

Claims (1)

[Claims] In a method for producing a propylene copolymer by a bulk polymerization method using propylene itself as a medium using titanium trichloride modified with an oxygen-containing organic compound and dialkyl aluminum halide, 1 to 20% by volume based on the total amount of the liquid medium. In the presence of an aromatic hydrocarbon compound having 6 to 10 carbon atoms, using a dialkyl aluminum halide having an atomic ratio of halide to aluminum of 0.90 to 1.10, ethylene and/or ethylene and carbon number Copolymerization is carried out so that the sum of α-olefins 4 to 6 is 10% by weight or less in the total copolymer, and the copolymer slurry is then washed in countercurrent with propylene.It has excellent transparency. A method for producing a propylene copolymer.