JP3107634B2 - Method for separating polyolefin particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a method for separating tack-free polyolefin particles from a hydrocarbon solvent.

[0002]

2. Description of the Related Art
Polyolefins having rubber elasticity are used for various applications similar to rubber. However, the polyolefin having rubber elasticity has a large amount of an amorphous polymer portion, so the polymer itself has tackiness, and is rarely obtained in the form of particles by polymerization, and is obtained in the form of particles. Even so, it is difficult to obtain smooth particles with good fluidity because the particles adhere to each other due to the stickiness of the particles.

When the fluidity of the polyolefin particles is insufficient, problems such as shelf fishing in the hopper may occur, and the polyolefin particles may be clogged in the piping by pneumatic transportation, making it difficult to handle. There was a problem.

[0004]

Means for Solving the Problems The present inventors have made intensive studies for the purpose of solving the above-mentioned problems, and as a result,
The inventors have found that polyolefin particles having good particle properties can be obtained by flashing and drying a slurry of polyolefin particles under specific conditions, thereby completing the present invention.

That is, the present invention relates to a method for producing a slurry of polyolefin particles obtained by polymerizing an olefin in a medium containing a hydrocarbon solvent having 6 or more carbon atoms. 500 solvent
Flash to 0 ppm or less, and further 100
The solvent is dried at a volatilization rate of at least 200 ppm / min until the amount becomes 0 ppm, and the amount of the hydrocarbon solvent having 6 or more carbon atoms contained in the obtained polyolefin particles is 1000 ppm.
A method for separating polyolefin particles characterized by the following.

The polyolefin particles used in the present invention may be either homopolymers or copolymers of α-olefins. In particular, the effect of the present invention is remarkable in the case of polyolefin particles having a p-xylene soluble content of 30% by weight or more at room temperature. Polyolefin particles having a p-xylene soluble content of 30% by weight or more at room temperature contain a large amount of an amorphous polymer portion, so that the particles easily adhere to each other. The cause is considered to be that the amorphous polymer portion is easily dissolved in a hydrocarbon solvent having 6 or more carbon atoms, and the dissolved material bleeds on the particle surface. Specific examples of the polyolefin particles suitably used in the present invention include, for example, an ethylene-propylene random copolymer, an ethylene-propylene block copolymer, an ethylene-butene random copolymer, and an ethylene-butene block copolymer. Α- such as propylene-butene random copolymer, propylene-butene block copolymer, ethylene-propylene-butene random copolymer, ethylene-propylene-butene block copolymer, ethylene-propylene-diene random copolymer, etc. Copolymers of two or more olefins can be given.

The above-mentioned polyolefin particles have 6 carbon atoms.
It is obtained by polymerizing an olefin in a medium containing the above-mentioned hydrocarbon solvent (hereinafter, may be simply referred to as a hydrocarbon solvent). As the above-mentioned hydrocarbon solvent, a hydrocarbon solvent generally used as a diluent for a catalyst, for example, a solvent having a low boiling point such as hexane, heptane, cyclohexane, octane and decane is used.

[0008] As the medium containing the above-mentioned hydrocarbon solvent,
Propane, butane, commonly used for the polymerization of olefins,
It may be a saturated hydrocarbon medium having 3 to 5 carbon atoms such as pentane; or a polymerized monomer having 3 to 5 carbon atoms such as propylene, butene and pentene.

The amount of the hydrocarbon solvent having 6 or more carbon atoms contained in the medium is not particularly limited, but when it is too small, it is possible to obtain sufficient fluid polyolefin particles without using the present invention. When the amount is too large, it may be difficult to provide sufficient fluidity according to the present invention. Therefore, when the olefin is polymerized using a medium containing the hydrocarbon solvent in the range of 0.1 to 10% by volume, the effect of the present invention is sufficiently exhibited, which is preferable.

For the polymerization of the olefin in the medium described above, a known method can be employed without any limitation. For example, a method of randomly copolymerizing different types of olefins, a method of sequentially block copolymerizing different types of olefins, and the like can be given. The concentration of the slurry containing the polyolefin in the polymerization system is preferably in the range of 10 to 50% by weight.

In this manner, a slurry in which polyolefin particles are dispersed in a medium can be obtained. The present invention
The above slurry is first flashed to reduce the amount of hydrocarbon solvent contained in the resulting polyolefin particles to 5
It is important that the content is not more than 000 ppm. Even after flashing, when the amount of the hydrocarbon solvent contained in the obtained polyolefin particles exceeds 5000 ppm,
Polyolefin particles having good fluidity cannot be obtained.

As a method of flashing to the above-mentioned amount of the hydrocarbon solvent, the following conditions may be specifically adopted. That is, a method in which a sufficient amount of heat is added to the latent heat of vaporization of the medium at a temperature of -40 to 140 ° C. and a pressure of 0 to 20 kgG / cm ² to keep the medium in a gaseous state may be employed. In addition, spraying an inert gas at a temperature of about 10 ° C. lower than the melting point of the obtained polyolefin at about 80 ° C. to the vicinity of the flash nozzle tip,
It can be suitably employed in the present invention.

In the present invention, the amount of the hydrocarbon solvent contained in the obtained polyolefin particles is then 100
The volatilization rate of the hydrocarbon solvent until 0 ppm
It is important to dry at more than ppm / min. As described above, by setting the rate of volatilization of the hydrocarbon solvent until the amount of the hydrocarbon solvent contained in the obtained polyolefin particles reaches a constant value, an extremely high rate of 200 ppm / min or more, fluidity is extremely good. Polyolefin particles can be obtained. When the volatilization rate of the hydrocarbon solvent is lower than the above-mentioned value, the obtained polyolefin particles adhere to each other to deteriorate the fluidity, and further, the polyolefin particles are aggregated and cannot be obtained as particles.

The volatilization rate of the hydrocarbon solvent is 250 ppm /
Min or more, and more preferably 300 ppm / min or more,
It is preferable to improve the particle properties of the obtained polyolefin particles.

In the present invention, the amount of the hydrocarbon solvent contained in the obtained polyolefin particles is 1000 ppm.
The volatilization rate of the hydrocarbon solvent up to the above greatly affects the particle properties of the obtained polyolefin particles.
When the amount of the hydrocarbon solvent contained in the obtained polyolefin particles is less than 1000 ppm, the effect of the volatilization rate of the hydrocarbon solvent on the particle properties of the obtained polyolefin particles is almost eliminated. For this purpose, the amount of the hydrocarbon solvent contained in the obtained polyolefin particles is reduced to 1000
When it is lower than ppm, the volatilization rate of the hydrocarbon solvent in the range of less than 1000 ppm is not limited to the above-mentioned volatilization rate, and may be any rate.

The method for volatilizing a hydrocarbon solvent at the above-mentioned volatilization rate is preferably carried out at a drying temperature of 0 to 140 ° C, preferably 40 to 100 ° C.
Further, it is preferable to adopt a method of reducing the pressure or promoting the flow of an inert dry gas into the system in order to promote the volatilization of the hydrocarbon solvent.

In the present invention, the amount of the hydrocarbon solvent contained in the polyolefin particles obtained after volatilizing the hydrocarbon solvent at the above-mentioned volatilization rate must be 1000 ppm or less. 1000 ppm of hydrocarbon solvent
If it exceeds, it is not preferable because even if the hydrocarbon solvent is volatilized at the above-mentioned volatilization rate, polyolefin particles having good fluidity and other particle properties cannot be obtained. In the present invention, in order to obtain polyolefin particles having good fluidity, the amount of the hydrocarbon solvent contained in the obtained polyolefin particles is preferably 400 ppm or less, more preferably 300 ppm or less.

[0018]

The polyolefin particles separated by the method of the present invention have a smooth feel and good fluidity. Therefore, in the handling of the above polyolefin particles, for example, there is no problem such as shelf fishing in the hopper, and even if a transportation method such as pneumatic transportation is adopted, the polyolefin particles are not clogged in the piping, Further, when the above-mentioned polyolefin particles are mixed with another resin, a filler or the like, the mixing with other components can be performed uniformly.

[0019]

EXAMPLES The measuring method used in the examples is as follows.

(1) Measurement of the amount of a hydrocarbon solvent having 6 or more carbon atoms contained in the polyolefin particles.

1) About 100 g of polyolefin particles are placed in a sample bottle with a rubber stopper, left in a dryer kept at a constant temperature of 130 ° C. for one hour, and thereafter, the gas in the sample bottle is sampled by a microsyringe, and then subjected to gas chromatography. And the gas composition was analyzed.

2) The weight of the weighing bottle in a constant temperature state was measured (weight A), and about 30 g of polyolefin particles were placed in the weighing bottle and the weight was measured (weight B). Then, vacuum drying (<1 mm) with a vacuum dryer at a constant temperature of 70 ° C. for 4 hours.
Hg) (weight C).

C6 contained in the polyolefin particles
Amount (ppm) of the above hydrocarbon solvent = (BC) / (BA) ×
10 ⁶ × weight ratio of carbon atoms of 6 or more (%) by gas analysis (2) Bulk specific gravity The bulk specific gravity was measured in accordance with JIS K6721.

(3) Dropping seconds The metal funnel having a 10 mm outlet at the center of the bottom, a height of 175 mm, an inner diameter of the upper cylindrical portion of 68 mm, and a height of the cylindrical portion of 60 mm is placed on the metal funnel.
0 ml was charged, and the polyolefin particles were discharged while giving a vibration of 2 mm width in the lateral direction, and the time (sec) required for discharging the entire amount was measured.

(4) Room temperature p-xylene soluble matter About 1 g of polyolefin particles were weighed (weight A), added to 100 ml of p-xylene, heated to 130 ° C. with stirring, and further stirred for 30 minutes. A homogeneous p-xylene solution was prepared. After cooling to room temperature (23 ° C.)
Left for hours. The precipitated gel was filtered off, and the amount of soluble matter (weight B) was determined by completely volatilizing p-xylene, which was calculated by the following equation.

Room temperature p-xylene solubles (wt%) = B /
A × 100 Example 1 As a catalyst, titanium trichloride (“TO” manufactured by Marubeni Solvay Chemical Co., Ltd.)
S-17 ") Using diethylaluminum chloride,
After pre-polymerization with propylene, as main polymerization, first, 1-butene is polymerized in the presence of the pre-polymerization catalyst, diethylaluminum chloride, and an electron donor in an amount of 0.8% by weight of the total polymerization amount. In the presence, in 200 l of liquid propylene, the polypropylene component was polymerized at 30 wt% of the total polymerization amount, and then ethylene was fed to copolymerize propylene and ethylene.

The liquid propylene contained 0.3 vol% of heptane used as a diluent for the catalyst component, diethylaluminum chloride and the electron donor.

After the completion of the polymerization, the obtained slurry was flushed into a flash tank in which the internal temperature was previously set at 60 ° C.

During the flushing, a dry N ₂ gas at 120 ° C. was supplied near the tip of the flush nozzle at a flow rate of 120 m ³ /
hr. A portion of the flushed polymer particles were sampled and the amount of heptane was determined to be 34.
It was 00 ppm. The polymer particles that had been subjected to the flash operation were immediately transferred to a dryer and started drying at an internal temperature of 50 ° C. with stirring.

Samples were taken every three minutes from the time of drying, and the amount of heptane contained in the particles was measured. In this case, it was 990 ppm after 9 minutes. The state of the polymer particles in the agitated state in the dryer was extremely smooth, and drying was continued for 2 hours under the same conditions.
The heptane content after 2 hours was 260 ppm. At this time, the bulk specific gravity of the particles was 0.40 g / cc, and the falling seconds were 1
It was 7 seconds.

This polymer had a yield of 30 kg, an ethylene content of 31 mol%, and a p-xylene soluble matter at room temperature of 62 kg.
wt%.

Examples 2 to 4 and Comparative Examples 1 and 2 A slurry obtained by polymerization in the same manner as in Example 1 was flashed and dried under the conditions shown in Table 1. Table 1 shows the results
It was shown to. All of the particles obtained in the examples had a smooth feeling, but the particles obtained in the comparative example were in a state where the particles adhered to each other.

[0033]

[Table 1]

Continuation of the front page (56) References JP-A-51-18780 (JP, A) JP-A-50-37854 (JP, A) JP-A-59-166506 (JP, A) Table 7-506383 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08F 6/10-6/12 C08J 3/09

Claims (1)

(57) [Claims] 1. A slurry of polyolefin particles obtained by polymerizing an olefin in a medium containing a hydrocarbon solvent having 6 or more carbon atoms, the amount of the hydrocarbon solvent having 6 or more carbon atoms contained in the obtained polyolefin particles is reduced. Flashing to 5000 ppm or less, and further drying at a volatilization rate of 200 ppm / min or more to 1000 ppm,
A method for separating polyolefin particles, wherein the amount of the hydrocarbon solvent having 6 or more carbon atoms contained in the obtained polyolefin particles is 1000 ppm or less.