JPH0680101B2 - Process for producing block copolymer of propylene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a propylene block copolymer. More specifically, the present invention relates to a method for producing a block copolymer using a catalyst that has been subjected to a specific treatment, under the condition that substantially no inert medium is present.

[Conventional technology]

Polypropylene is a polymer having excellent rigidity, but its impact resistance, especially at low temperatures, is inferior, so impact resistance has been improved by block copolymerization with other olefins such as ethylene. (For example, JP-B-43-11230, JP-B-44-20621, etc.) However, when block copolymerization is carried out, the impact resistance is improved but the rigidity is inevitably lowered. Therefore, in order to achieve a good balance between rigidity and impact resistance, various methods have been proposed such as a reaction ratio of a portion to be copolymerized with another olefin such as ethylene in the latter stage, or a molecular weight of the portion in an appropriate range. ing. (For example, JP-B-47-7141 and JP-A-55-4315.
2, JP-A-54-139693, JP-A-56-55416, JP-A-58
-83015 etc.) [Problems to be solved by the invention] Although a block copolymer having a relatively good balance of physical properties has been obtained by the above-mentioned method, the polymerized part of propylene alone in the first stage and the ethylene in the second stage or Only those having a certain degree of physical property balance can be obtained by the ratio of other olefin and propylene copolymerization part, and further development of a method for producing a block copolymer having an improved physical property balance is desired.

[Means for solving problems]

The present inventors have earnestly studied 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 using a catalyst comprising a transition metal catalyst and an organoaluminum compound, wherein the catalyst is selected from alkyl-substituted styrene, trialkylvinylsilane and trialkylallylsilane in an inert medium. 1
After the pre-contact treatment with the seed compound, in the bulk polymerization method using propylene itself as a medium, or in the gas phase polymerization method, the ratio of the propylene alone is substantially 50 to 95 in the total polymer.
A method for producing a block copolymer of propylene, which comprises polymerizing to a weight% and then polymerizing propylene and ethylene in a ratio of ethylene and propylene in the range of 20/80 to 95/5.

In the present invention, the catalyst comprising a transition metal catalyst and an organoaluminum compound is not particularly limited, and various known catalyst systems which give polypropylene having high stereoregularity can be used. Titanium halide is preferably used as the transition metal catalyst, for example, titanium trichloride obtained by reducing titanium tetrachloride with metallic aluminum, hydrogen or organic aluminum, or those obtained by modifying them with an electron donating compound and an organic aluminum compound. Further, if necessary, a catalyst system comprising a stereoregularity improver such as an oxygen-containing organic compound, or a carrier such as magnesium halide or a product obtained by treating them with an electron-donating compound and supporting titanium halide thereon. An example is a catalyst system comprising an organoaluminum compound and, if necessary, a stereoregularity improver such as an oxygen-containing compound. (For example, various examples are described in the following literature. Ziegler-Natta Catalysts and Polymeri
zation by John Boar Jr (Academic Press), or Jou
rnal of Makromolecular Science Reviews in Makromol
ecular Chemisty and Physics C24 (3) 355-385 (198
4) Same C25 (1) 57-97 (1985)) Here, the stereoregularity improver or electron donor is usually an ether, ester,
Oxygen-containing compounds such as orthoesters and alkoxysilicons are preferably used, and alcohols, aldehydes, water and the like can also be used as electron donors.

As the organic aluminum compound, trialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, and alkylaluminum dihalide can be used.Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, and hexyl group. Is exemplified by chlorine, bromine and iodine.

Preferred titanium halides are aluminum or organoaluminum, those obtained by modifying titanium tetrachloride obtained by reducing titanium tetrachloride with ether or ester, or those obtained by co-milling magnesium chloride and an organic compound. What was treated with titanium tetrachloride or the reaction product of magnesium chloride and alcohol was dissolved in a hydrocarbon solvent and then treated with a precipitating agent such as titanium tetrachloride to make it insoluble in the hydrocarbon solvent and, if necessary, ester, ether, etc. Is a supported titanium halide obtained by a method such as a modification treatment with the electron-donating compound (1) and a treatment with titanium tetrachloride.

What is important in the present invention is that the catalyst is previously subjected to contact treatment with one compound selected from alkyl-substituted styrene, trialkylvinylsilane and trialkylallylsilane in an inert medium. Examples of the alkyl residue include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and the like. For example, pt-butylstyrene, trimethylvinylsilane, trimethylallylsilane, diethylmethylvinylsilane, triethylvinylsilane, Specific examples include triethylallylsilane and dimethylethylallylsilane.

The ratio of the organoaluminum compound / transition metal catalyst used in this contact treatment may be the same as or smaller than the ratio in the subsequent propylene polymerization, and the ratio is 0.5 to 1000. Is common. In that case, it is also possible to allow a stereoregularity improver to be present,
The preferable ratio is 0.01 to 300.

There is no particular limitation on the contact treatment temperature and the contact treatment time, but generally, the temperature is the same as or lower than the temperature during the subsequent polymerization of propylene, and the contact treatment time is several minutes to several hours, preferably Is to treat under the condition that the compound to be subjected to the above-mentioned contact treatment reacts with 0.001 equivalent or more per transition metal catalyst. This contact treatment is pentane,
Hexane, heptane, octane, nonane, decane, benzene, toluene, xylene, ethylbenzene or a mixture thereof is carried out in an inert medium for the Ziegler-Natta catalyst, and the above-mentioned unreacted compounds are removed and washed if necessary. Further, an organoaluminum compound can be added and used for the polymerization of propylene.

The amount of the compound used in the above-mentioned contact treatment is preferably 0.01 equivalent times or more per transition metal catalyst, 0.01
There is almost no effect of less than equivalent times. Further, even if treated under the condition of reacting 200 equivalent times or more, it is not more effective, and when the obtained block copolymer is molded, problems such as a defective surface occur.

In the present invention, propylene is first polymerized using the catalyst subjected to the above treatment. At this time, 0.06 for propylene
It is also possible to copolymerize another olefin such as ethylene in a weight ratio or less to improve the surface gloss and the whitening at the time of down brow of the obtained block copolymer. Polymerization of propylene should be 50% by weight or more and 95% by weight or less of the total polymer. If the amount is less than 50% by weight, the rigidity is insufficient.
If it exceeds 5% by weight, the impact resistance improving effect is insufficient. The polymerization is carried out by a bulk polymerization method or a vapor phase polymerization method using propylene itself as a medium, the polymerization temperature is room temperature to 100 ° C., and the polymerization pressure is normal pressure to 50 Kg / cm ² gauge. The amount of polymerization per transition metal catalyst in this part is generally about 1000 to 4000.

Then, propylene and ethylene are copolymerized by a bulk polymerization method or a gas phase polymerization method in which substantially no inert medium exists. 5 to 50% by weight as a polymerization ratio with respect to the total amount of polymerization in the part
If it is less than 5% by weight, the improvement of impact resistance is insufficient, and if it is more than 50% by weight, the rigidity is insufficient. In the copolymerization of propylene and ethylene, it is preferable that the ratio of ethylene and propylene is 20/80 to 95/5 weight ratio, and impact resistance is not improved even if it is less than 20/80 or more than 95/5 weight ratio. Will be enough. Here, butene-1 and hexene-1 may be substituted for part of ethylene. The reaction in this part is usually carried out under the conditions of normal temperature to 80 ° C. and normal pressure to 50 kg / cm ² gauge.

[Action and effect]

Although the reason is not clear by carrying out the method of the present invention, the crystallization temperature of the obtained block copolymer is increased,
As a result, rigidity, especially bending rigidity and impact resistance, especially Izod impact strength, are significantly improved, and a block copolymer having an extremely excellent balance of physical properties is obtained, which is industrially extremely valuable.

〔Example〕

 The present invention will be further described below with reference to examples.

Example 1 A vibration mill equipped with four grinding pots with an inner volume of 4 containing 9 kg of steel balls having a diameter of 12 mm is prepared. 300 g magnesium chloride and tetraethoxysilane in a nitrogen atmosphere in each pot
60 ml and 45 ml of α, α, α-trichlorotoluene were added and crushed for 40 hours.

300 g of the above co-ground product was placed in a flask of 5 and titanium tetrachloride was added.
1.5 and toluene 1.5 were added and the mixture was stirred at 100 ° C. for 30 minutes. Then, leave it still to remove the supernatant liquid,
1.5 and toluene 1.5 were added, the mixture was stirred at 100 ° C. for 30 minutes, the supernatant was removed, and the solid content was washed with n-heptane (4) 10 times. When a part was sampled and the titanium content was analyzed, it was 1.9% by weight.

40 ml of toluene under a nitrogen atmosphere in a flask with an internal volume of 200 ml,
30 mg of the above solid catalyst, diethylaluminum chloride 0.
Add 128 ml, methyl p-toluate 0.06 ml, triethylaluminum 0.03 ml, and pt-butylstyrene 0.3 g 40
The mixture was stirred at 30 ° C for 30 minutes. Similarly, when another model experiment was carried out, the weight of pt-butylstyrene per transition metal catalyst was 0.4 equivalent. This catalyst slurry was put into an autoclave with an internal volume of 5 and 1.5 kg of propylene and hydrogen.
3.3Nl was added and the polymerization reaction was performed at 75 ° C for 2 hours. Then, the internal temperature was lowered to 40 ° C, ethylene was added at 5 kg / cm ² gauge, 0.25 ml of triethylaminium was injected, and ethylene was added at a partial pressure of 5 kg / cm ² -gauge, but polymerization was performed for 60 minutes. Unreacted propylene and ethylene were purged, taken out from the autoclave and dried.

The ratio of the copolymerization part of the block copolymer and the reaction ratio of the copolymerization part were determined by the column fractionation method (Proceedings of the 13th Lecture of the Joint Autumn Meeting of the Chubu Chemistry Association, Chapter 3A20). In addition, the reaction ratio of the copolymerized portion is determined based on the ratio X of the copolymerized portion and the ethylene content Y of the block copolymer, that is, the reaction ratio ethylene / propylene = Y / (X-
Y).

The block copolymer was granulated by adding a phenolic stabilizer in the ratio of 10/10000 and calcium stearate in the ratio of 15/1000, and the melt flow index was measured.
The following physical properties were measured by making an injection sheet of.

Melt flow index ASTM D1238 (230 ℃) Tensile strength ASTM D638-64T (20 ℃) Flexural rigidity ASTM D747-63 (20 ℃) Izod (with notch) Impact strength ASTM D256-56 (20 ℃, -10 ℃) DuPont Impact strength JIS K6718 (20 ℃, -10 ℃) The results are shown in Table 1. The polypropylene powder shown in Table 1 has a limiting viscosity number of 135 ° C. in tetralin solution and boiling n-
Heptane extraction residue (abbreviated as II) is 6 in boiling n-heptane.
It is the ratio when time is extracted.

Examples 2-3, Comparative Example 1 Trimethylvinylsilane (Example 2), trimethylallylsilane (Example 3), as compounds to be subjected to contact treatment in advance,
Nothing was used (Comparative Example 1), and otherwise the same as in Example 1. The results are shown in Table 1. The polymerization amount of each compound of Example 2 and Example 3 was 0.6 equivalent and 0.7 equivalent.

Example 4 and Comparative Example 2 As the transition metal catalyst, a highly active titanium trichloride catalyst (TGY24) manufactured by Marubeni Solway Co. was used. In a flask with an internal volume of 200 ml, 40 ml of toluene under a nitrogen atmosphere, 100 mg of titanium trichloride catalyst,
Diethyl aluminum chloride (0.5 ml), trimethylallylsilane (0.3 ml) (Example 4), and trimethylallylsilane not used (Comparative example 2) were each added at 40 ° C.
And stirred for 30 minutes. This catalyst slurry was placed in an autoclave having an internal volume of 5, 1.5 kg of propylene and 4.0 Nl of hydrogen were added, and a polymerization reaction was carried out at 65 ° C for 2 hours. Then the internal temperature is 40 ℃
The temperature was lowered to 8 kg / cm ^{2 of} ethylene. Polymerization was carried out for 60 minutes while adding a gauge and adding ethylene so that the ethylene partial pressure became constant. Others are Example 1
I went the same way. The results are shown in Table 1.

〔effect〕

As shown in the examples, by carrying out the method of the present invention, a block copolymer having a good balance of rigidity and impact resistance, particularly excellent in bending rigidity and Izod impact strength, can be obtained and is industrially extremely valuable. .

[Brief description of drawings]

FIG. 1 is a flow chart of the Ziegler catalyst according to the present invention.

Claims (1)

[Claims] 1. A method for producing a block copolymer of propylene using a catalyst comprising a transition metal catalyst and an organoaluminum compound, wherein the catalyst is selected from alkyl-substituted styrene, trialkylvinylsilane, and trialkylallylsilane in an inert medium. In a bulk polymerization method or a gas phase polymerization method in which propylene itself is used as a medium after a contact treatment with one of the above compounds, the proportion of the propylene alone in the total polymer is 50 to 95. A method for producing a block copolymer of propylene, which comprises polymerizing to a weight percentage and then polymerizing propylene and ethylene at a ratio of ethylene and propylene of 20/80 to 95/5.