JP2917412B2 - Method for producing propylene copolymer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a propylene-based copolymer. More specifically, a powdery propylene copolymer having excellent powder properties without adhesion between polymer particles or on the inner wall of a reactor, or clogging of a pipe in a later step, or consolidation in a silo, a hopper or the like. The present invention relates to a method for manufacturing a united product.

The propylene-based copolymer referred to in the present invention is a general term including a random copolymer of propylene and another α-olefin and a block copolymer of propylene and another α-olefin.

[Prior art] Polypropylene is a so-called Ziegler-based polymer mainly composed of a solid catalyst component containing titanium and an organoaluminum compound.
It is obtained by propylene homopolymerization or copolymerization of propylene with another olefin using a Natta catalyst.

Known polymerization methods include a method of performing polymerization in the presence of an inert hydrocarbon solvent, a method of performing polymerization in liquefied propylene, and a method of performing polymerization in a gas phase substantially in the absence of an inert solvent or liquefied propylene. ing.

However, in random copolymers and block copolymers of propylene and other olefins, the amount of by-products of the amorphous polymer component is large, and due to the stickiness of the powder surface, the fluidity of the powder is poor. Also, the bulk density is reduced, and in extreme cases, it may cause troubles such as adhesion to various devices such as reactors and hoppers, cease to flow due to bridging, or aggregation and sticking.

For this reason, especially in the production of random copolymers and block copolymers, the amount of copolymerization of olefins other than propylene is limited to a low region due to restrictions on powder properties as described above,
There were manufacturing restrictions. In the gas phase polymerization method, it is said that such problems in powder properties are somewhat reduced, but are still insufficient. Further, in the production of block copolymers, adhesion and formation of lumps in the reactor not only cause a great hindrance for stable operation, but also lead to deterioration of product quality.

[Problems to be Solved by the Invention] The present inventors have conducted intensive studies on a method of preventing the above-described adhesion phenomenon in the reactor and the phenomenon of powder property deterioration, and as a result, it has been found that in the presence of a propylene polymer having a specific property, The present inventors have found that copolymerization of propylene with another α-olefin significantly improves the powder properties of the copolymer, and arrived at the present invention.

[Means for Solving the Problems] That is, the gist of the present invention is to provide a method for copolymerizing propylene with another α-olefin using a catalyst comprising a titanium-containing solid catalyst component and an organoaluminum compound. In the first step, polymer particles of a propylene homopolymer or a copolymer of propylene and a small amount of another α-olefin having a pore volume of 0.15 to 0.30 cc per 1 g of the polymer particles are produced. In the method, a propylene copolymer is produced by copolymerizing propylene with another α-olefin in the presence of the polymer particles.

Here, the pore volume indicates the internal pore volume, which is obtained by measuring the pore volume by the mercury intrusion method, taking the cumulative pore volume on the vertical axis, and the pore volume distribution curve with the pore diameter on the horizontal axis. The portion corresponding to the pore diameter below the rapidly rising portion of the cumulative pore volume was defined as the internal pores, and was distinguished from the external pore volume. The cumulative volume up to the rising portion was defined as the internal pore valley area.

 Hereinafter, the present invention will be described sequentially.

The polymerization catalyst used in the present invention is a stereospecific catalyst comprising a titanium-containing solid catalyst component and an organoaluminum compound. As the titanium-containing solid catalyst component,
A catalyst component containing titanium trichloride as a main component, a solid magnesium compound, a titanium compound component, and a carrier-supporting catalyst component containing a halogen component can be used. As a material containing titanium trichloride as a main component, conventionally known titanium trichloride can be used. For example, titanium trichloride which has been activated by ball milling; titanium trichloride obtained by solvent extraction; β-type titanium trichloride is treated with a complexing agent such as ethers, and further treated with titanium tetrachloride. , Al content
Titanium trichloride with an atomic ratio to Ti of 0.15 or less; in the presence of ethers or thioethers, titanium tetrachloride is treated with an organoaluminum compound to form a liquid, which is further heated and solidified at a temperature of 150 ° C or less. Deposited as Al
Titanium trichloride whose content is 0.15 or less in atomic ratio to Ti;

Particularly preferred among these titanium trichlorides, the aluminum content is 0.15 or less, preferably 0.1 or less, more preferably 0.1 or less, in the atomic ratio of aluminum to titanium.
It is 0.02 or less and contains a complexing agent such as ethers.

As specific examples of the production method of these titanium trichloride,
JP-B-55-8452, 55-8451, 55-8003, 54-4104
0, 55-8931, JP-A-58-36928, 59-12905, 59-1
3630 and the like.

In the present invention, the above catalyst may be used as it is, but as a pretreatment, it is preferable to preliminarily polymerize a small amount of an α-olefin in advance on a catalyst comprising a titanium-containing solid catalyst component and an organoaluminum compound.

The above method is to add a titanium-containing solid catalyst component and an organoaluminum compound to an inert solvent, for example, hexane, heptane, etc., and to supply propylene, ethylene, α-olefin such as 1-butene, or a mixture thereof. What is necessary is just to polymerize. This pretreatment is a means generally referred to as prepolymerization, and known polymerization conditions can be employed as they are. The polymerization temperature is usually from 10 to 70 ° C.
The polymerization rate is preferably as large as possible per unit weight of the solid catalyst component.
Generally, the amount of prepolymerization per unit is in the range of 0.1 to 100 g. During the polymerization, a molecular weight regulator such as hydrogen may be added. Further, the prepolymerization is preferably carried out uniformly in a batch system. This preliminary polymerization is effective in improving the properties of the polymer such as the bulk density.

In the first polymerization step of the present invention, a catalyst comprising the above-mentioned titanium-containing solid catalyst component and an organoaluminum compound may be used, and an additive for improving stereoregularity may be used as a third component. The organoaluminum compound used as a cocatalyst is represented by the general formula ▲ AIR ¹ _m ▼ X ₃ -m (wherein R
¹ is a hydrocarbon group having 1 to 20 carbon atoms, X represents halogen,
m is a number satisfying 3 ≧ m> 1.5). Titanium-containing solid catalyst component, if a carrier supported catalyst component containing a solid magnesium compound, to use ▲ AIR ¹ ₃ ▼ or ▲ AIR ¹ ₃ ▼ and ▲ AIR ¹ ₂ ▼ mixture of X preferable. On the other hand, titanium-containing solid catalyst component, three if the titanium chloride as the main component is, ▲ AIR ¹ ₂ ▼ but using the X, generally diethyl aluminum chloride, di -n- propyl aluminum chloride, dihexyl aluminum chloride, di - n-Octyl aluminum chloride is preferred.

The titanium-containing solid catalyst component and the organoaluminum compound shown above are generally used in a molar ratio of the organoaluminum compound / titanium of 1 to 300, preferably 2 to 150.

The third component for improving stereoregularity is N, O, P or S
Various electron donating compounds including i and the like, and hydrocarbon compounds are used. The addition amount of the third component is generally in the range of 0.001 to 100 mol, preferably 0.01 to 50 mol, per 1 mol of titanium.

Examples of the electron donating compound include compounds containing one or more electron donating atoms or groups, such as ethers, polyethers, alkylene oxides, furans, amines, trialkylphosphines, triarylphosphines, pyridines, and quinolines. , Phosphoric acid ester, phosphoric amide, phosphine oxide, trialkyl phosphite, triaryl phosphite, ketone, carboxylic acid ester, carboxylic acid amide and the like. Among them, preferred are carboxylate esters such as ethyl benzoate, methyl benzoate, phenyl acetate and methyl methacrylate;
Examples include glycine esters such as dimethylglycine ethyl ester and dimethylglycine phenyl ester, and triaryl phosphites such as triphenyl phosphite and trinonyl phenyl phosphite.

Also, aromatic hydrocarbons such as benzene, toluene and xylene can be used.

For the polymerization of propylene, a commonly used method can be adopted. Examples of the method include a method performed in a liquid phase in the presence of an inert hydrocarbon, liquefied propylene, and the like, and a method performed in a gas phase under the condition that these liquid phases are not substantially present. Such polymerizations include propylene homopolymerization and random copolymerization of propylene with small amounts of other α-olefins.

In the production of the block copolymer, the above-mentioned propylene homopolymerization or the copolymerization of propylene with a small amount of other α-olefin in the former stage, and then without deactivating the catalyst, successively in the latter stage, other than propylene α-
The copolymerization of olefin alone or propylene and an α-olefin other than propylene with the polymer obtained in the preceding step is performed. The second stage polymerization method is the same as the first stage, slurry polymerization,
Gas phase polymerization or the like can be employed, but gas phase polymerization is preferred.

The reactor for the gas phase polymerization is a fluidized vessel in which the polymer particles containing the catalyst component are caused to flow by the gaseous monomer or the gas containing the gaseous monomer, and in order to smoothly mix the polymer particles. Various types, such as a type equipped with a stirring blade, may be used, and may be a batch type or a continuous type.

The reaction conditions are usually 1 to 100 atm, preferably 5 to 4 atm.
The reaction is carried out at a pressure of 0 atm and at a temperature of 50 to 90 ° C, preferably 60 to 80 ° C.

In addition, as a method for controlling the molecular weight of the produced polymer, a known molecular maximum regulator such as hydrogen or diethylzinc can be appropriately added.

The most important technical feature of the present invention is that the propylene homopolymer produced in the previous step or propylene and a small amount of other α-
By having a specific pore volume of the copolymer with olefin, the powder properties of the propylene-based copolymer are improved, and adhesion between polymer particles or on the inner wall of the reactor, or clogging of pipes, silos, hoppers, etc. Is to prevent caking and the like.

The pore volume is preferably 0.15 to 0.3 cc per gram of a propylene homopolymer or a copolymer of propylene and a small amount of another α-olefin.

When the pore volume is less than 0.15 cc / g, the effect of improving the powder properties is small. On the other hand, if it is more than 0.3 cc / g, powder properties such as low bulk density of propylene homopolymer or copolymer of propylene and a small amount of other α-olefin are unfavorably deteriorated. There are various methods for controlling the pore volume within the above range. For example, there is a method for appropriately selecting the conditions for the prepolymerization.

[Examples] Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited thereto without departing from the gist thereof. In the following Examples and Comparative Examples, the bulk density and the pore volume were measured by the following methods, respectively.

(1) Bulk density JIS K-6721 (2) Pore volume Measured by a mercury intrusion method in a pressure range of 0.5 psia to 53330 psia using a pore distribution measuring device (Autopore 9200) manufactured by Shimadzu Corporation.

Example 1 (A) Preparation of Solid Titanium Trichloride Catalyst Complex To a 10 l autoclave sufficiently purged with nitrogen, 5.0 l of purified toluene and 5.0 mol of titanium tetrachloride were charged, and 5.0 mol of di-n-butyl ether was further added.

2.38 mol of diethylaluminum chloride was added dropwise while maintaining the temperature at 25-30 ° C. with stirring, whereby a homogeneous solution of black triturated titanium trichloride was obtained. Next, the temperature of the homogeneous solution of titanium trichloride was raised to 40 ° C. and maintained for 2 hours. In this process, precipitation of purple titanium trichloride was observed.

At this point, 1.6 mol of titanium tetrachloride and 0.57 mol of tridecyl methacrylate were further added.
Stirring was continued for hours. Thereafter, the precipitate was separated by filtration and washed repeatedly with n-hexane to obtain a fine-grained purple solid titanium trichloride catalyst complex.

(B) Production of propylene polymer-containing titanium trichloride Purified in a 10 l autoclave sufficiently purged with dry nitrogen
5 liters of hexane and diethyl aluminum chloride
After charging 195 g and 250 g of the solid titanium trichloride catalyst complex obtained in the above (A) as TiCl ₃ , the mixture was kept at 60 ° C. and stirred.
250 g of propylene gas was blown into the liquid phase for about 60 minutes to perform a contact treatment.

Next, the solid component was allowed to settle down by standing, the supernatant was removed by decantation, and washed several times with n-hexane to obtain a solid titanium trichloride containing a propylene polymer.

(C) Production of propylene-ethylene block copolymer A reaction vessel with a stirrer with a capacity of 1000 l and one gas-phase polymerization vessel of a stirring fluidized tank type with a capacity of 1500 l are connected in series, and homopolymerization of propylene is performed in a first reaction vessel. In liquefied propylene,
In the second reaction tank, copolymerization of propylene and ethylene was performed in the gas phase.

In the first reactor, liquefied propylene, 4.0 g / hr of the catalyst component obtained in the above (B), 10 g / hr of cocatalyst diethylaluminum chloride, 0.52 g / hr of methyl methacrylate, and 0.15 kg of hydrogen as a molecular weight regulator / hr was supplied continuously.
The polymerization temperature was 70 ° C. The average residence time was 3.0 hours. The pore volume of the propylene polymer obtained here was 0.20 cc / g.

The polymer slurry from the first tank was continuously supplied to the second tank, and gas phase polymerization was performed while maintaining the temperature at 60 ° C. and the pressure at 15 kg / cm ² G. The composition of ethylene and propylene in the gas phase is propylene / (ethylene + propylene) = 65 mol%, H ₂
/ (Ethylene + propylene) = 15 mol%.

The average residence time of this gas phase reactor is 2.5 hours. The polymer continuously withdrawn from the second tank was separated from the reaction gas and then treated with propylene oxide vapor to obtain a powdery polymer at a rate of 45 kg / hr.

This operation was performed continuously for 30 days, the whole system was stable, and the reactor was opened after the operation was completed.As a result, no adhesion or lumps were observed in the vessel as observed in Comparative Examples described later. Was.

The ratio of the homopolymerized portion to the copolymerized portion of the polymer obtained during this period was 65/35 on average. The bulk density of the powder was 0.42 g / cc.

Comparative Example 1 Preliminary polymerization was carried out at 40 ° C in Example-1 (B). In this case, the pore volume of the propylene polymer in the first tank was 0.12 cc / g. Otherwise, a continuous operation for 14 days was performed in the same manner as in Example 1.

The bulk density of the polymer powder obtained during this time is 0.26 g / cc
It was a low rank.

Further, after the operation was completed, the reactor was opened, and as a result, formation of lumps around the axis of the stirring blade in the reactor was observed. Further, deposits were also formed on the free board portion and the dispersion plate.

From these results, by making the propylene homopolymer or the copolymer of propylene and a small amount of other α-olefin a specific pore volume, the powdery properties of the propylene-based copolymer, and further the agglomeration of the polymer particles It can be seen that a great effect is brought about in improving the adhesion to the inner wall of the reactor.

[Effects of the Invention] By the production method of the present invention, it is possible to produce a propylene-based polymer excellent in powder properties without causing agglomeration of polymer particles or adhesion to the inner wall of a reactor, and is extremely useful in industry. is there.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C08F 251/00-292/00 C08F 210/00-210/18

Claims (2)

(57) [Claims] 1. A method comprising: using a catalyst comprising a titanium-containing solid catalyst component and an organoaluminum compound;
In the method of copolymerizing with an olefin, the pore volume per 1 g of the polymer particles is 0.1 in the first step.
15 to 0.30 cc of propylene homopolymer or polymer particles of a copolymer of propylene and a small amount of another α-olefin is produced, and in the second step, propylene and other copolymer particles are produced in the presence of the polymer particles. A process for producing a propylene-based copolymer, characterized in that the copolymerization with α-olefin is carried out. 2. The method according to claim 1, wherein the copolymerization of propylene with another α-olefin is carried out in a gas phase substantially free of a liquid phase.