JPH0118929B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [] Background of the Invention The present invention relates to a method for producing an olefin polymer having extremely excellent heat resistance. More specifically, we use olefin polymers with excellent heat resistance as raw materials for branched α-
This invention relates to a method for producing olefins with extremely low isomerization and high catalyst yield. In general, the melting point of isotactic polymers of α-olefins is closely related to the structure of the α-olefin, and in the case of linear α-olefins, as the number of carbon atoms increases, the melting point of the polymer tends to decrease; In the case of branched α-olefins, the melting point of the polymer tends to be higher as the degree of branching increases or the position of the branching is closer to the carbon-carbon double bond. Therefore, isotactic polymers of branched α-olefins, especially those with a branch on the carbon atom adjacent to the double bond (third carbon atom), are of industrial significance because of their high melting points. is big. On the other hand, such branched α-olefins are linear α-olefins.
-Polymerization rate is extremely low compared to olefins,
This tendency is particularly pronounced when the branch is at the tertiary carbon atom. In fact, 4-methylpentene-1
Because the branch position is at the carbon atom at the 4-position, the polymerization rate is relatively high even for branched α-olefins, but the polymerization rate of 3-methylbutene-1, which has a branch at the 3-position carbon atom, is relatively high. is extremely small. This is clear, for example, from the example of Japanese Patent Publication No. 17966/1983. That is, the publication discloses a method for polymerizing a branched α-olefin using a catalyst in which titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound is combined with an organometallic activator. It can be seen that 4-methylpentene-1 gave a maximum of 260 g/g or more of polymer to the titanium trichloride used in 2 hours, whereas 3-methylbutene-1 gave only 3 g/g or less of polymer. . Another difficult problem associated with branched α-olefin polymerization is that the carbon-carbon double bond of α-olefin moves in parallel with the polymerization reaction of α-olefin and isomerizes into various internal olefins. A reaction occurs. Although it is theoretically possible that these isomers are isomerized to α-olefin again and participate in the polymerization reaction, macroscopically, thermodynamically more stable internal olefin gradually accumulates. In particular, in industrial processes in which unreacted monomers are repeatedly used, it is necessary to add a step to remove such internal olefins from the system, leading to a rise in construction costs and raw material costs. In view of these circumstances, the present inventors have conducted intensive studies on a method for polymerizing α-olefin having a branch at the 3rd-position carbon atom at a high polymerization rate, and as a result, have completed the present invention. [] Summary of the Invention The method for polymerizing olefins according to the present invention involves the homopolymerization or polymerization of α-olefins having a branch at the 3rd position carbon atom using a catalyst comprising a combination of a titanium trichloride-containing solid and an organoaluminum compound. In the method of copolymerizing with other olefins, the titanium trichloride-containing solid does not contain aluminum trichloride at all or has a molar ratio of 0.1 to _TiCl3 .
This method is characterized by using a compound containing only the following aluminum trichloride, and using trimethylaluminum as the organic aluminum compound. According to the method of the present invention, the α-olefin having a branch at the 3rd position carbon atom is converted into a polymer at a polymerization rate several times higher than that by other methods, and the branched α-olefin as a raw material is is hardly isomerized to internal olefins, thus preventing the polymerization rate from decreasing due to accumulation of internal olefins. [] DETAILED DESCRIPTION OF THE INVENTION Olefin The olefin polymerized by the method of the present invention is an α-olefin having a branch at the tertiary carbon atom. Such α-olefins usually have 5 or more carbon atoms.
12, preferably from 5 to 9, and selected from those having the structure represented by the following general formula. In the formula, R ¹ is a methyl group or an ethyl group, R ² is an alkyl group having 1 to 5 carbon atoms, and R ³ is hydrogen, a methyl group, or an ethyl group. Examples of monomers represented by the above general formula include 3-methylbutene-
Examples include 1,3-methylpentene-1,3-ethylpentene-1, 3-methylhexene-1, 3,5-dimethylhexene-1, 3,5,5-trimethylhexene-1, etc. . Among these branched α-olefins, preferred are 3-methylbutene-1 and 3,5,
5-trimethylhexene-1. The method for polymerizing olefins according to the present invention is directed not only to homopolymerization of the above-mentioned branched α-olefins but also to copolymerization of the above-mentioned branched α-olefins with other olefins that can be copolymerized. In that case, the proportion of these olefins in the final polymer should be at most 50 mol%, preferably 40 mol%, and more preferably 30 mol% or less. This is because copolymers with these olefins have improved impact resistance and moldability compared to the branched α-olefin homopolymers, but on the other hand, the heat resistance of the homopolymers is impaired. It is from. Also,
The copolymerization referred to herein includes not only random copolymerization but also block copolymerization and a combination of both. The olefins used in the copolymerization for this purpose are selected from linear or branched α-olefins having 2 to 12 carbon atoms and linear internal olefins having 4 to 12 carbon atoms. When copolymerizing with an internal olefin, so-called monomer isomerization copolymerization occurs, and the resulting copolymer contains α-olefin units corresponding to the internal olefin used. The advantage of copolymerizing internal olefins is that the polymerization rate of the corresponding α-olefin is high, and when it is necessary to reduce the monomer concentration in the raw material gas and it is difficult to control the concentration, internal olefins can be used to reduce the concentration. There is a place where you can increase your Examples of olefins that can be used for such copolymerization purposes are ethylene, propylene, butene-1, pentene-1, hexene-1, octene-1, nonene-1, decene-1, undecene-1, dodecene-1
1,4-methylpentene-1,4,4-dimethylpentene-1,4-methylhexene-1,5-methylhexene-1,5,5-dimethylhexene-
α-olefins such as 1 and internal olefins such as butene-2, pentene-2, hexene-2, heptene-2, octene-2, 4-methylpentene-2, and hexene-3 (however, cis and trans isomers are Either can be used). Among these, preferred olefins are linear α-olefin and linear 2-olefin. Specific examples of particularly preferred olefins are ethylene, propylene, 1-butene, 1-hexene, 1-4-methylpentene, and 2-butene. In addition to these olefins, copolymerization of α-olefins having a branch at the third carbon atom listed above is also included within the scope of the present invention. Titanium trichloride-containing solid The titanium trichloride used in the method of the present invention is
Contains no AlCl ₃ or its content is 0.1 (molar ratio) to TiCl ₃ , preferably 0.05,
More preferred is titanium trichloride with a molecular weight of 0.03 or less. If a titanium trichloride-containing solid containing AlCl ₃ exceeding the above-mentioned molar ratio is used instead of the titanium trichloride-containing solid, or if TiCl ₄ is used, a high polymerization rate cannot be obtained. For example, a titanium-containing catalyst component with a magnesium chloride carrier, which is known to exhibit high activity in the polymerization of ethylene and propylene, also has high activity against α-olefins having a branch at the 3rd-position carbon atom, which is the subject of the present invention. does not indicate. Examples of titanium trichloride that can be used in the present invention include (1) TiCl ₄ reduced with hydrogen and further activated by pulverization, and (2) TiCl ₄ reduced with metallic titanium and further activated. activated by grinding, (3)
It is obtained by reducing TiCl ₄ with an organoaluminium compound, and is a complex mainly composed of TiCl ₃ and AlCl ₃ .
(4) TiCl ₄ which is treated with a complexing agent for AlCl ₃ to extract and remove all or most of the AlCl ₃ and then activated by heat treatment, grinding treatment or chemical treatment with TiCl ₄ ; It is obtained by reducing TiCl 3 with metallic aluminum, and mainly contains TiCl ₃ and
A complex consisting of AlCl ₃ was prepared in the same manner as above.
Examples include those obtained by extraction and removal of AlCl ₃ and activation treatment. Among these, the latter two of the above four examples of titanium trichloride are particularly preferred. Regarding such complex extractable type titanium trichloride, Japanese Patent Application Laid-Open Nos. 47-34478 and 48-64170
No. 51-151787, No. 52-40348, No. 52-
Detailed information can be found in Publications No. 138083 and No. 52-49996. Although the mechanism of polymerization inhibition caused by the presence of AlCl ₃ in the α-olefin polymerization of the present invention is unknown,
It is clear that this is not simply due to physical causes such as the size of the specific surface area. Organoaluminium Compound The organoaluminium used in the method of the invention is trimethylaluminum. For the purpose of simply forming a highly active catalyst system in combination with the specific titanium trichloride described in the previous section, compounds more commonly used industrially such as triethylaluminum and triisobutylaluminum are used as organoaluminum compounds. be able to. However, it has been found that when these organoaluminums are used, the branched α-olefin used as the raw material is isomerized to the corresponding internal olefin in parallel with the high polymerization reaction. Although such internal olefins do not themselves appear to reduce the activity of the catalyst, they have been found to gradually accumulate and reduce α-olefin concentrations. On the other hand, when trimethylaluminum is used as the organoaluminium, not only is the polymerization rate comparable to that of the other organoaluminiums mentioned above, but it has also been found that almost no internal olefin is produced as a by-product. Although the mechanism by which trimethylaluminum exhibits this unique effect is not clear, it is speculated as follows. That is, the active center involved in the isomerization of branched α-olefins is the Ti-H bond, and this bond is responsible for the β-hydrogen abstraction between trialkylaluminum and titanium trichloride, which have β-hydrogen in the alkyl group. This is thought to be due to the reaction. Therefore, when trimethylaluminum is used as trialkylaluminum, the methyl group does not have β-hydrogen, so no Ti-H bond is formed, and isomerization of branched α-olefin to internal olefin does not occur. I think that the. The titanium trichloride and trimethylaluminum usually have an Al/Ti molar ratio of 0.3 to 5.0, preferably 0.5.
-3.0, more preferably in the range of 0.7-2.5. The polymerization activity decreases when the amount deviates from either side of the above range. It is also possible to improve the activity and stereospecificity by adding various electron-donating compounds to the two-component catalyst system. Polymerization Method Except for the use of specific monomers and catalysts, the method for polymerizing olefins according to the present invention is essentially the same as general olefin polymerization using a Ziegler type polymerization catalyst. That is, the polymerization can be carried out in the presence of a diluent such as an inert hydrocarbon, or by suspension polymerization using the monomer itself as a medium without using substantially an inert medium. Examples of diluents when using diluents include:
Examples include hexane, heptane, cyclohexane, benzene, toluene, refined kerosene, and the like. Polymerization temperature is usually room temperature to 200°C, preferably 50°C to
Selected from the range of 150℃. The polymerization pressure is usually atmospheric pressure ~ 50 kg/cm ² , preferably atmospheric pressure ~ 30 kg/cm ² , more preferably atmospheric pressure ~ 15 kg/cm 2
Selected from the range of Kg/cm ² (all above gauge pressure). The polymerization method may be either a batch method or a continuous method. Example 1 After sufficiently purging the inside of a glass tube with an internal volume of about 25 ml connected to a vacuum system with nitrogen, 2 ml of n-heptane,
0.45 mmol of titanium trichloride (titanium trichloride obtained by reducing TiCl ₄ with hydrogen and activated by pulverization; commercially available product) and trimethylaluminum
1.35 mmol was added in this order. After aging this mixture at room temperature (approximately 27°C) for one hour, 3-methyl-1
-11.5 mmol of butene was added and the glass tube was sealed. Place the glass tube in a constant temperature bath kept at 80℃.
3-Methyl-1-butene was homopolymerized by shaking for 5.0 hours. After breaking the glass tube and recovering the unreacted monomer, the residue was poured into a large amount of methanol acidified with hydrochloric acid to precipitate the produced polymer. The solid polymer was separated, washed repeatedly with methanol, and then dried under vacuum. Isomerization of the recovered unreacted monomers was monitored by gas chromatography. From the respective weights of dry polymer and charged 3-methyl-1-butene, the polymer yield based on the charged monomer was calculated to be 50.8%. Analysis of isomers by gas chromatography after completion of polymerization revealed that the internal olefins produced by isomerization of 3-methyl-1-butene were 2-methyl-2-butene and 2-methyl-1-butene, and unreacted monomers. The amount of isomer in it was 6.9%. Example 2 As titanium trichloride, the molar ratio of TiCl ₃ and AlCl ₃ obtained by reducing TiCl ₄ with metal aluminum was approximately 3.
Most of the AlCl ₃ was extracted and removed by treatment of the pair-1 complex with diisoamyl ether, and
Activated by treatment with TiCl ₄ (commercial product; residual AlCl ₃ to TiCl ₃ molar ratio analytical value 1/
3-Methyl-1-butene was homopolymerized under the same conditions as in Example 1 except that 69.7) was used. The polymer yield was 56.7%. The internal olefin produced by isomerization is the same as in Example 1,
The percentage was 5.7%. Comparative Example 1 3-Methyl-1-butene was homopolymerized under the same conditions as in Example 1 except that triethylaluminum was used instead of trimethylaluminum. Polymer yield was 50.4%. The internal olefin produced by isomerization is the same as in Example 1,
The percentage was 56.4%. Comparative Example 2 3-Methyl-1-butene was homopolymerized under the same conditions as in Example 2 except that triethylaluminum was used instead of trimethylaluminum. The polymer yield was 56.2%. The internal olefin produced by isomerization is the same as in Example 1,
The percentage was 52.1%. Comparative Example 3 3-Methyl-1-butene was homopolymerized under the same conditions as in Example 1 except that triisobutylaluminum was used instead of trimethylaluminum. The polymer yield was 61.7%. The internal olefin produced by isomerization is the same as in Example 1,
The percentage was 98.7%. Comparative Example 4 3-Methyl-1-butene was homopolymerized under the same conditions as in Example 2 except that triisobutylaluminum was used instead of trimethylaluminum. The polymer yield was 59.3%. The internal olefin produced by isomerization is the same as in Example 1,
The percentage was 97.6%. Example 3 7.5 mmol of vinylcyclohexane was used instead of 3-methyl-1-butene, and titanium trichloride was used.
0.32m mol and trimethylaluminum
Vinylcyclohexane was homopolymerized for 15 hours under the same conditions as in Example 1 except that 0.64 mmol was used. The polymer yield was 60.4%. After completion of the polymerization, isomer analysis by gas chromatography revealed that the internal olefin produced by isomerization of vinylcyclohexane was ethylidenecyclohexane, and the proportion of the isomer in the unreacted monomer was 3.0%. Comparative Example 5 Vinylcyclohexane was homopolymerized under the same conditions as in Example 3 except that triethylaluminum was used instead of trimethylaluminum. The polymer yield was 38.0%. The internal olefin produced by isomerization was the same as in Example 3, and its proportion was 15.0%. Comparative Example 6 Vinylcyclohexane was homopolymerized under the same conditions as in Example 3 except that triisobutylaluminum was used instead of trimethylaluminum. The polymer yield was 52.0%, and the internal olefin produced by isomerization was the same as in Example 3, and its proportion was 32.8%. Example 4 3,5,5- instead of 3-methyl-1-butene
3,5,5-trimethyl-1-hexene was homopolymerized for 20 hours under the same conditions as in Example 1 except that 8.0 mmol of trimethyl-1-hexene was used. Polymer yield was 7.2%. After polymerization,
From the analysis of isomers by gas chromatography,
The internal olefins produced by isomerization of 3,5,5-trimethyl-1-hexene are cis and trans 3,5,5-trimethyl-2-hexene and cis and trans 3,5,5-trimethyl-3-
Hexene and 2-ethyl-4,4-dimethyl-
1-pentene, and the proportion of internal olefin formed was 0.3%. Example 5 3, 5,
5-Trimethyl-1-hexene was homopolymerized. Polymer yield was 5.3%. The internal olefin produced by isomerization was the same as in Example 4, and its proportion was 0.7%. Comparative Example 7 3,5,5-trimethyl-1-hexene was homopolymerized under the same conditions as in Example 4 except that triethylaluminum was used instead of trimethylaluminum. Polymer yield was 8.6%. The internal olefin produced by isomerization was the same as in Example 4, and its proportion was 13.2%. Comparative Example 8 3,5,5-trimethyl-1-hexene was homopolymerized under the same conditions as in Example 4 except that triisobutylaluminum was used instead of trimethylaluminum. Polymer yield was 13.7%. The internal olefin produced by isomerization was the same as in Example 4, and its proportion was 15.3%. Comparative Example 9 3,5,5-trimethyl-1-hexene was homopolymerized under the same conditions as in Example 5 except that triethylaluminum was used instead of trimethylaluminum. Polymer yield was 10.0%. The internal olefin produced by isomerization was the same as in Example 4, and its proportion was 10.0%. Comparative Example 10 3,5,5-trimethyl-1-hexene was homopolymerized under the same conditions as in Example 5 except that triisobutylaluminum was used instead of trimethylaluminum. The polymer yield was 6.5%, and the internal olefin produced by isomerization was the same as in Example 4, and its proportion was 18.7%. Examples 6 to 8 In Example 2, 3-methyl-1-butene
Instead of 11.5 mmol, the comonomers shown in Table 1 and 3
Polymerization was carried out in the same manner as in Example 2, except that the mixture with -methyl-1-butene was used in the amounts shown in Table 1. The results are shown in Table 1. 【table】

[Brief explanation of drawings]

FIG. 1 is intended to assist in understanding the technical content of the present invention regarding Ziegler catalysts.

Claims (1)

[Claims] 1. A method for homopolymerizing an α-olefin having a branch at the 3rd position carbon atom or copolymerizing it with another olefin using a catalyst comprising a combination of a titanium trichloride-containing solid and an organoaluminum compound. A titanium trichloride-containing solid containing no aluminum trichloride or a molar ratio of aluminum trichloride to titanium trichloride of 0.1 or less is used as the titanium chloride-containing solid, and trimethylaluminum is used as the organoaluminum compound. A method for polymerizing olefin, which is characterized by: