JP2590180B2 - Method for producing propylene polymer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a propylene polymer having excellent crystallinity.

2. Prior Art A propylene polymer is a resin having high rigidity and high mechanical strength, but higher rigidity is required for some applications.

In order to improve the rigidity of polypropylene, many attempts have been made to improve the polymerization catalyst and to improve the crystallinity by prepolymerization.

For example, JP-A-60-139731, JP-A-61-151204
JP-A-61-155404 discloses that the prepolymerization of a branched α-olefin increases the crystallinity of polypropylene in the subsequent main polymerization. However, there was a problem that the bulk density was lowered and the productivity was significantly deteriorated.

[Summary of the Invention]

SUMMARY OF THE INVENTION The present invention provides high polymerization by performing propylene homopolymerization or copolymerization of propylene with an olefin other than propylene (hereinafter sometimes referred to as main polymerization in the present specification) after performing two specific steps in advance. Attempts to economically produce rigid polypropylene.

That is, the method for producing a propylene polymer according to the present invention comprises the steps of homopolymerizing propylene or copolymerizing propylene with an olefin other than propylene in the presence of a catalyst comprising a titanium-containing solid catalyst (A) and an organoaluminum compound (B). , The following two steps are performed in this order prior to the polymerization.

Step (1) A step of polymerizing 0.05 to 100 g of propylene per 1 g of the titanium-containing solid catalyst (A).

Step (2) A step of polymerizing 0.05 to 100 g of a branched α-olefin per 1 g of the titanium-containing solid catalyst (A).

Effects According to the present invention, it is possible to economically produce high-rigidity polypropylene in which the bulk density of the product powder is dramatically improved and the crystallinity of the product is also improved.

[Specific description of the invention]

[Catalyst component] The catalyst used in the present invention comprises the component (A) and the component (B). Here, “comprising the component (A) and the component (B)” means that a case where the composition contains a third component that does not unduly impair the effects of the present invention or a third component that more preferably acts advantageously in the present invention. It should be understood that this is not to exclude. Representative of such third component is, for example, an electron donating compound (component (C)), wherein the catalyst comprising components (A), (B) and (C) is a preferred embodiment of the present invention. It is what makes.

Titanium-containing solid catalyst (component (A)) Examples of the titanium-containing solid catalyst used in the present invention include a titanium trichloride catalyst and a magnesium chloride carrier-type catalyst. As the titanium trioxide catalyst, for example, α, β, γ, or δ-type titanium trichloride, or a titanium compound obtained by reducing titanium tetrachloride with organoaluminum and then subjecting it to complex extraction is used. In particular, from aluminum trichloride-containing titanium trichloride (which is considered to be a eutectic composite of titanium trichloride and aluminum chloride) obtained by reducing titanium tetrachloride using an organoaluminum compound, aluminum chloride using a complexing agent is used. Is most suitable.

As such a titanium trichloride catalyst, for example, a catalyst commercially available from Toho Titanium Co., Marubeni Solvay Co., or the like can be suitably used. On the other hand, as a magnesium chloride support type catalyst, for example, JP-A-61-78803, JP-A-62-11705, JP-A-62-11706, can be suitably produced by the method described in it can.

The solid catalyst component may be one in which a so-called internal electron donor is added at any stage of the production process. As the electron donor therefor, the following component (C)
An appropriate one can be selected from those exemplified above.

Organoaluminum Compound (Component (B)) The organoaluminum compound used in the present invention is preferably trialkylaluminum or dialkylaluminum chloride, specifically, Al (CH ₃ ) ₃ , A1 (C ₂ H ₅ ) ₃ , Al _{(i-C 4 H 9)} 3, Al (C 3 H 5) 2 Cl, Al (i-C 4 H 9) , and the like ₂ Cl. Also,
Those obtained by partially alkoxylating these alkyl groups may be used. Each of these can be used alone, or two or more of them can be used in combination.

The amount of the organoaluminum compound to be used is 1 to 1000, preferably 2 to 200, in a molar ratio to the titanium component.

Electron-donating compound (component (C)) An electron-donating compound (component (C)) can be added to components (A) and (B) for the purpose of improving the stereoregularity of the polymer during polymerization. is there. As such a component (C), for example, an organic carboxylic acid ester, an organic silicon compound or the like is preferably used. In particular,
Examples thereof include methyl benzoate, ethyl benzoate, ethyl p-anisate, ethyl terephthalate, diphenyldimethoxysilane, tert-butylmethyldimethoxysilane, and 2-norbornylmethyldimethoxysilane.

The amount of the electron-donating compound used is usually 0.01 to 1, preferably 0.05 to 1, in a molar ratio to the organoaluminum compound.
~ 0.5.

Production of Propylene Polymer The production method of the propylene polymer according to the present invention comprises a step (1) of polymerizing a small amount of propylene, a step (2) of polymerizing a branched α-olefin, and homopolymerization of propylene or propylene and propylene. And three steps of main polymerization in which copolymerization with an olefin other than the above is carried out, and has one feature that the steps (1) and (2) are performed in this order prior to the main polymerization. It is. Here, “the step (1) and the step (2) are performed in this order prior to the main polymerization” means that the polymer derived from the step (1) and the polymer derived from the step (2) are obtained before the start of the main polymerization. Are formed in this order, and then
This means that the main polymerization is started and the polymerization is terminated in a state where both of these polymers are present. By taking the above steps, the bulk density of the product powder can be improved.

Step (1) In step (1), 0.05 g / g of the titanium-containing solid catalyst (A) was used.
This is a step of polymerizing 100100 g of propyle. In this step, preferably 0.2 to 10 g, more preferably 0.5 to 5 g of propylene is polymerized per 1 g of the solid catalyst (A). The polymerization amount of propylene is 0.1 g / g of the titanium-containing solid catalyst (A).
If it is less than 05 g, the bulk density of the product powder is insufficient, while if it exceeds 100 g, the effect of the step (2) becomes insufficient, which is not preferable.

This step is preferably performed in the presence of an inert solvent, for example, a known hydrocarbon solvent such as hexane, heptane, and kerosene. The reaction pressure is normal pressure to 20 atm, preferably normal pressure to 5 atm, and the reaction temperature is 0 to 100 ° C, preferably 10 to 50 ° C.

This step can be carried out by either a continuous method or a batch method. However, it is preferable to carry out the method in a batch method because the effect of improving the bulk density of the product powder is large.

Step (2) In step (2), 0.05 g / g of the titanium-containing solid catalyst (A) was used.
This is a step of polymerizing 100100 g of a branched α-olefin. In this step, preferably 0.2 g / g of the solid catalyst (A) is used.
5050 g, more preferably 0.5-20 g, of the branched α-olefin is polymerized. Polymerization amount per g of solid catalyst (A)
If it is less than 0.05, the crystallinity of the product is insufficient, while 100 g
Excessive amounts are not preferred because the bulk density of the product powder is reduced.

The branched α-olefin preferably has 5 to 10 carbon atoms, and particularly preferably has a specific branch position at a carbon atom adjacent to a carbon atom having a double bond. Specific examples of such a branched α-olefin are as shown below.

3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4,4-dimethyl-1-
Pentene, 4-methyl-1-hexene, 4-ethyl-1
-Hexene and the like. Most preferred of these is 3-methyl-1-butene. These can be used alone or as a mixture of two or more as needed.

This step (2) is also preferably performed in the presence of an inert solvent as in step (1). As the inert solvent, known hydrocarbon solvents such as hexane and heptane can be used as in the step (1). The reaction temperature is 0 to 100 ° C, preferably 20 to 80 ° C.
° C. The reaction pressure is preferably normal pressure to 50 atm, more preferably normal pressure to 10 atm.

This step can be carried out by any of a continuous method and a batch method, but it is preferable to carry out the method by a batch method for the same reason.

Main polymerization The main polymerization is carried out under the coexistence of the polymer produced in the above step (1) and the polymer produced in the step (2).
This is a step of performing homopolymerization of propylene or a copolymerization of propylene with an olefin other than propylene, and is a step of obtaining a polymer of 95% or more of the total polymerization amount. Other olefins to be copolymerized with propylene include those having 2 to 6 carbon atoms.
Olefin such as ethylene, butene-1, hexene-1 and the like. Therefore, in the present polymer, propylene homopolymer, propylene and ethylene,
Polymers having various structures such as a random copolymer with butene-1 or hexene-1 or a block copolymer of propylene and ethylene can be produced.

As the polymerization mode, slurry polymerization performed in an inert solvent, liquid phase bulk polymerization performed in a propylene solvent, gas phase polymerization performed in a gaseous propylene atmosphere, and the like are used.

The polymerization pressure is normal pressure to 100 atm, preferably normal pressure to 40 atm, and the polymerization temperature is 30 to 90 ° C, preferably 50 to 80 atm.
° C.

This step can be preferably performed by either a continuous method or a batch method.

In addition, hydrogen can be used as a molecular weight regulator.

The following examples further illustrate the present invention (although the present invention is not limited thereto).

〔Example〕

Example-1 Step (1) 1.5 liter of purified heptane, 30 g of titanium trichloride manufactured by Marubeni Solvay, and 90 g of diethylaluminum chloride were introduced into a 3 liter stirred autoclave in a nitrogen atmosphere, and 40 g of propylene was further added. After the introduction, propylene polymerization was carried out at 30 ° C. for 1 hour. Thereafter, washing was performed with purified heptane to remove residual diethylaluminum chloride and propylene. The polymerization amount of propylene was 1.2 g / g of titanium trichloride.

Step (2) Following the above step, 1.5 liters of purified heptane, 120
g of 3-methyl-1-butene and 90 g of diethylaluminum chloride were introduced and reacted at 50 ° C. for 3 hours. Thereafter, the residue was washed with purified heptane to remove the remaining diethylaluminum chloride and 3-methyl-1-butene. 3-methyl-1-butene polymerization amount is 1 g of titanium trichloride.
The weight was 3.4 g.

Main Polymerization A 3-liter stirred autoclave was sufficiently replaced with propylene, and then sufficiently dehydrated n-heptane 1.5.
Liter, keep at 65 ° C and propylene 7kg / cm
Pressurized to ² G. Furthermore, diethyl aluminum chloride 1.
0 g, 0.1 g of the solid catalyst having undergone the prepolymerization step as titanium trichloride was introduced, and polymerization was carried out at 65 ° C. for 3 hours while adjusting the gas phase hydrogen concentration to 2.0 vol%. , Polymerization was stopped by adding 10 ml of butanol, followed by filtration and drying.
317 g of polypropylene powder were obtained. The polymerization results and the quality evaluation results were as shown in Table 1.

In addition, each physical property in Table 1 was measured according to the following method.

MFR: ASTM-D-1238 Flexural modulus: ASTM-D-790 Comparative Example-1 The same experiment was performed as in Example-1, except that step (1) was omitted. The polymerization results and the quality evaluation results are as shown in Table 1. The bulk density of the product is significantly lower than that of Example 1, and the productivity is significantly lower. Further, the flexural modulus is also a low value.

Example 2 Preparation of Solid Catalyst Component 75 ml of purified heptane was placed in a 500 ml three-neck glass flask (with a thermometer and a stirrer) having an internal volume of 500 ml.
Of titanium tetrabutoxide and 10 g of anhydrous magnesium chloride. Thereafter, the temperature of the flask is raised to 90 ° C., and the magnesium chloride is completely dissolved over 2 hours. Next, the flask is cooled to 40 ° C., and 15 ml of methylhydrogenpolysiloxane is added to precipitate a magnesium chloride-titanium tetrabutoxide complex. After washing with purified heptane, 8.7 ml of silicon tetrachloride and 2.0 g of phthaloyl chloride are added, and the mixture is kept at 50 ° C. for 2 hours. Thereafter, the resultant is washed with purified heptane, 25 ml of titanium tetrachloride is further added, and the mixture is kept at 25 ° C. for 2 hours. This was washed with purified heptane to obtain a solid catalyst component.

 The titanium content in the solid catalyst component was 2.7% by weight.

Step (1) 500 ml of purified heptane, 8 g of the solid catalyst prepared as described above, and 2 g of triethylaluminum were introduced into a 1-liter stirred autoclave in a nitrogen atmosphere, 10 g of propylene was further introduced, and propylene polymerization was performed at 30 ° C. for 1 hour. Was performed. Thereafter, washing was performed with purified heptane to remove residual triethylaluminum and propylene. The propylene polymerization amount was 1.1 g per 1 g of the solid catalyst.

Step (2) Following the above step, 500 ml of purified heptane, 32 g of 3-
Methyl-1-butene and 2 g of triethylaluminum were introduced and reacted at 50 ° C. for 3 hours. Thereafter, washing was performed with purified heptane to remove residual triethylaluminum and 3-methyl-1-butene. The polymerization amount of 3-methyl-1-butene was 2.1 g / g of the solid catalyst.

Main Polymerization A 3-liter stirred autoclave was sufficiently replaced with propylene, and then sufficiently dehydrated n-heptane 1.5.
Introduce liters and maintain at 75 ° C, then 7k with propylene
g / cm ² G. Further triethyl aluminum 0.38
g, 0.16 g of diphenyldimethoxysilane and 30 mg of the solid catalyst were introduced, and polymerization was carried out at 75 ° C. for 3 hours while adjusting the hydrogen concentration in the gas phase to 0.3 vol%. Thereafter, propylene was purged, and the polymerization was stopped by further adding 10 ml of butanol, followed by over-drying to obtain 421 g of polypropylene powder. The polymerization results and the quality evaluation results were as shown in Table 1.

Comparative Example-2 The same experiment was performed as in Example-2 except that step (1) was omitted. The results of the polymerization and the results of the quality evaluation are as shown in Table 1. However, the bulk density of the product is significantly lower than that of Example 2, and the productivity is significantly lower. Further, the flexural modulus is also low.

Comparative Example-3 Preparation of solid catalyst component The same operation as in Example-2 was performed.

Step (1) 500 ml of purified heptane, 8 g of the solid catalyst prepared as described above, and 2 g of triethylaluminum were introduced into a 1-liter stirred autoclave in a nitrogen atmosphere.
32 g of methyl-1-butene was introduced and reacted at 50 ° C. for 3 hours. Thereafter, washing was performed with purified heptane to remove residual triethylaluminum and 3-methyl-1-butene. The polymerization amount of 3-methyl-1-butene was 2.1 g / g of the solid catalyst.

Step (2) Following the above steps, purified heptane 500 ml, propylene 1
After introducing 0 g and 2 g of triethylaluminum, propylene polymerization was carried out at 30 ° C. for 1 hour. Thereafter, washing was performed with purified heptane to remove residual triethylaluminum and propylene. The polymerization amount of propylene was 1.1 g / g of the solid catalyst.

The polymerization results and the quality evaluation results performed in the same manner as in Example 2 of the main polymerization are as shown in Table 1. However, the catalyst yield and the bulk density of the product were significantly reduced as compared with Example 2. And productivity has declined significantly. Further, the flexural modulus is also low.

[Brief description of the drawings]

FIG. 1 is to assist in understanding the technical contents of the present invention relating to the Ziegler catalyst.

Claims (2)

(57) [Claims] (1) When performing propylene homopolymerization or copolymerization of propylene with an olefin other than propylene in the presence of a catalyst comprising a titanium-containing solid catalyst (A) and an organoaluminum compound (B), prior to the polymerization, Wherein the following two steps are carried out in this order. Step (1) A step of polymerizing 0.05 to 100 g of propylene per 1 g of the titanium-containing solid catalyst (A). Step (2) A step of polymerizing 0.05 to 100 g of a branched α-olefin per 1 g of the titanium-containing solid catalyst (A). 2. The method according to claim 1, wherein the branched α-olefin is 3-methyl-1.
Claim 1 characterized in that it is butene
13. The method for producing a propylene polymer according to the above item.