JPH07103189B2 - Method for producing stereoregular acrylonitrile polymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel method for producing an acrylonitrile polymer having high stereoregularity. More specifically, the present invention provides a high molecular weight highly stereoregular acrylonitrile polymer useful as a fiber material excellent in mechanical strength and heat resistance in a wet state, a selective adsorption material for metals or a conductive polymer. The present invention relates to a method for efficiently and industrially producing under specific polymerization conditions.

[Conventional technology]

Conventionally, acrylonitrile polymer is excellent in bulkiness when formed into fibers, texture, heat retention, etc., and when a copolymerization component is introduced, it can be dyed in a vivid color tone and is also excellent in dyeing weather resistance. Because of its physical properties such as, it is widely used for clothing.

This acrylonitrile polymer is usually produced by polymerizing acrylonitrile using a radical polymerization initiator or an anionic polymerization initiator. However,
In the acrylonitrile polymer obtained by such a method, there is no regularity in the chemical structure as measured by the nuclear magnetic resonance method (hereinafter abbreviated as NMR). When this polymer is dissolved in a solvent and formed into a fiber or film, the crystallinity is low and mechanical properties are not sufficiently satisfactory, and the heat resistance, especially the heat resistance in a wet state, Inferior. In particular, when it is formed into fibers, it lacks dimensional stability, tensile strength, elastic modulus, etc., so it is used in high-quality clothing fields such as high-quality woven fabrics of polyacrylonitrile (hereinafter sometimes abbreviated as PAN) -based fibers. The current situation is that not only is the application to the industrial materials / space engineering field restricted, but also the application to the industrial materials / space engineering field is restricted.

On the other hand, it is known that when an inclusion compound of urea-acrylonitrile is irradiated with an actinic ray such as γ ray, an acrylonitrile polymer having stereoregularity, a so-called highly stereoregular acrylonitrile polymer is obtained. Stereoregularity obtained by this method is more than 0.35 acrylonitrile polymer, the improvement of the melting point in the presence of water is observed,
Further, the fiber has a feature that Young's modulus in hot water is remarkably improved as compared with the conventional PAN fiber, and heat resistance in a wet state is improved. Further, when a metal salt such as copper sulfate is added to the solution of the acrylonitrile polymer, the metal ion is selectively coordinated to the cyano group of the acrylonitrile polymer molecule in the meso position [[Polymer Journal] Vol. 18, p. 277 (1986)], it is also suitable as a material for selectively adsorbing metal or as a material for a conductive polymer.

However, in the method of irradiating the urea-acrylonitrile inclusion compound with γ-rays to obtain a highly stereoregular acrylonitrile polymer, it is necessary to cool the urea-acrylonitrile inclusion compound to about −30 ° C. or lower. , Γ
In order to require expensive cobalt 60 etc. as a radiation source,
The highly stereoregular acrylonitrile polymer obtained is inevitably very expensive.

Therefore, various attempts have been made to develop a method for producing a highly stereoregular acrylonitrile polymer without using such an actinic radiation source. Among these, as a method of producing an acrylonitrile polymer having the highest stereoregularity, except for the urea-acrylonitrile inclusion compound method, alkoxides and alkali metal amide compounds in a polar or nonpolar solvent are used. A method of polymerizing acrylonitrile using a complex as a polymerization initiator is known. [“European Polymer Journal” No. 22
Volume, p. 559 (1986)] However, the acrylonitrile polymer obtained by this method has a high stereoregularity with an isotactic fraction of about 0.4, but has a molecular weight of several thousands, and at most about 10,000. Therefore, if it is a fiber as an industrial use condition, and it is usually required to have a molecular weight of 10,000 or more even for other uses in the case of other applications, it must be said that it is one step less practical. .

[Problems to be Solved by the Invention]

The present invention overcomes various drawbacks of such a conventional method for producing a highly stereoregular acrylonitrile polymer, and has a high stereoregularity such that the isotactic fraction described below is 0.35 or more, And, it was made for the purpose of providing a method for easily and efficiently producing an acrylonitrile polymer having a molecular weight of 10,000 or more.

[Means for Solving the Problems]

The present inventors have diligently conducted research on the polymerization of acrylonitrile, and boldly carried out the polymerization of acrylonitrile at a temperature higher than the boiling point of acrylonitrile at atmospheric pressure (that is, 77 ° C.). It has been found that under the conditions, the stereoregularity of the acrylonitrile polymer can be dramatically increased to a level that has never been obtained by a polymerization method using a polymerization initiator.

That is, when acrylonitrile is polymerized at a polymerization temperature that exceeds the boiling point of acrylonitrile at atmospheric pressure using an appropriate organometallic compound as an initiator, the stereoregularity of the polyacrylonitrile obtained by this is obtained by conventional techniques. It is significantly improved compared to that of about 0.6 for high isotactic fractions.
It turned out to be Moreover, its molecular weight rises as the polymerization temperature rises, and exceeds 10,000 in usual cases.
In addition to obtaining PAN, it was found that PAN having a molecular weight of 100,000 or more was obtained depending on the conditions.

The organometallic compound used as the polymerization initiator may be any one that has the ability to initiate the polymerization of acrylonitrile, but most organometallic compounds initiate the polymerization of acrylonitrile, so there is no difficulty in selecting the organometallic compound. . However, among them, the organometallic compounds which can improve the stereoregularity are the organometallic compounds containing the metals of Group I, II and III of the Periodic Table with an alkali metal and an alkaline earth metal as the center. As a compound having a higher stereoregularity-improving effect, an organomagnesium compound and an organometallic compound called a so-called art complex, which is a combination of two or more metals of Group I, II and III of the Periodic Table, shows more remarkable stereoregularity. Can improve.

Even if a so-called Ziegler-Natta type initiator system that uses a combination of an organometallic compound and a fiber metal compound is used, it is possible to obtain a PAN having high stereoregularity by adopting the polymerization conditions shown in the present invention. there were.

Examples of chemical substances that can serve as an initiator exhibiting the effects of the present invention will be given below, but these examples do not limit the scope of the claims of the present invention.

First, as typical examples of the organometallic compound, alkyl lithium such as normal butyl lithium, ethyl lithium and methyl lithium; alkyl potassium such as isoamyl potassium and normal octyl potassium; alkyl sodium such as isoamyl sodium and normal octyl sodium; triethylaluminum; Alkyl aluminum such as triisobutyl aluminum; and alkyl boron such as trimethyl boron and triethyl boron. Further, it is also possible to use a transition metal compound in combination with these organometallic compounds. The transition metal compound is a part of the raw material of the polymerization initiator usually called Ziegler-Natta catalyst, and the main ones are dichlorotitanium, trichlorotitanium, tetrachlorotitanium, tetranormultipropoxytitanium, tetrahydroxy. There are many titanium compounds represented by titanium and dicyclopentadienyldichlorotitanium, vanadium compounds such as trichlorovanadium, tetrachlorovanadium, oxytrichloride vanadium and acetylacetone vanadium, and many other compounds such as trichlorochromium.

However, an organomagnesium compound is mentioned as an initiator that exhibits a greater effect. Specific examples thereof include dimethyl magnesium, diethyl magnesium, dinormal propyl magnesium and dinormal butyl magnesium represented by the formula R ₂ Mg (R ₂ is a hydrocarbon group consisting of an aliphatic or an aliphatic hydrocarbon or a combination thereof). , Diisoamylmagnesium, dinormalhexylmagnesium, diallylmagnesium, diphenylmagnesium and other organomagnesium compounds having two identical hydrocarbon groups, and two different hydrocarbons such as methylethylmagnesium, n-butylethylmagnesium and phenylethylmagnesium An organomagnesium compound having a group may be mentioned. Further, a so-called Grignard reagent RMgX (R is the same as above and X is halogen) is also effective as an initiator to exert the effect of the present invention. This includes ethyl magnesium chloride, normal butyl magnesium bromide,
Examples include phenyl magnesium iodide and benzyl magnesium fluoride.

Furthermore, the organomagnesium compound in which the alkyl group of the organomagnesium compound is replaced with an amine group, an alkoxy group, an alkylsilyl group, a thioalkoxy group, or a composite substituent thereof exhibits a higher effect. For example, R ₂ NM such as ethyldiethylaminomagnesium
Compound represented by gR, and bis (diethylamino)
Compounds represented by R ₂ NMgNR ₂ such as magnesium and bis (diphenylamino) magnesium (these 2
R in one of the formulas is the same as described above, but the _two Rs represented by R ₂ may be bonded to each other to form a heterocycle with the nitrogen atom to which they are bonded. ); A compound represented by the formula ROMgR (R is the same as the above) such as methoxyethyl magnesium; A compound represented by the formula ROMgOR (R is the same as the above) such as dimethoxymagnesium, diethoxymagnesium and dinormalbutoxymagnesium; A compound represented by the formula R ₃ SiMgSiR ₃ (R is as defined above) such as bis (trimethylsilyl) magnesium;
Formulas such as trimethylsilylethyl magnesium R ₃ SiMg
Compounds represented by R (R is the same as above); Compounds represented by the formula RSMgR such as thiomethoxyethyl magnesium (R is the same as above); Compounds represented by the formula RSMgSR such as bis (thiomethoxy) magnesium (R is the same as above) ) And a formula (R ₃ Si) ₂ NMgN (SiR ₃ ) such as bis (bis (trimethylsilyl) amino) magnesium
_And a compound represented by the formula (R ₃ Si) ₂ NMgR (R in both formulas is as defined above).

In addition, beryllium and calcium belonging to Group II of the Periodic Table, which are similar to magnesium, are attracting attention as an initiator having a large stereoregularity-producing effect in various organometallic compounds. Examples thereof include beryllium compounds such as diethyl beryllium in the form represented by the formula R ₂ Be, di-normal propyl beryllium, and normal butyl ethyl beryllium,
And beryllium compounds such as Grignard type phenyl beryllium chloride, allyl beryllium bromide and the like represented by the formula RBeX. Calcium compounds include R ₂ Ca such as diphenyl calcium and phenylethyl calcium, and RCaX such as ethyl calcium bromide and normal butyl calcium iodide (R in the four formulas is the same as above, and X is halogen).

Further, as an example of a so-called art complex in which two or more kinds of metals of groups I, II and III of the periodic table are combined, those represented by the following general formula can be mentioned. That is, M ¹ M ² R _3-n H _n , M ¹ AlR _4-n H _n , M ² AlR _5-n X _n , M ² (AlR
_4-n H _n ) ₂ , M ² AlR _5-n (NR ₂ ) _n , LiZnR _3-n (NR ₂ ) _n and L
i ₂ ZnR _4-n (NR ₂ ) _n .

Here, R in the formula, which may be the same or different, is a hydrocarbon group composed of an aliphatic or aromatic hydrocarbon or a combination thereof. M ¹ is a kind of metal selected from lithium, sodium and potassium, M ² is a kind of metal selected from magnesium, beryllium, calcium, zinc and cadmium, and X is fluorine, chlorine, bromine and iodine. It is a kind of element selected from the above, and n is zero or a positive integer and takes a value within the range where the subscript of 5-n, 4-n or 3-n in the same molecule is not negative. .

Specific examples of these organometallic compounds are M ¹ M ² R
Examples of _3-n H _n include triethyl sodium magnesium, methyldiethyl lithium magnesium, diisobutyl hydrosodium magnesium, normal butyl dihydro lithium magnesium. Examples of M ¹ AlR _4-n H _n include tetraethyl lithium aluminum, triethyl normal butyl lithium aluminum, tetraethyl potassium aluminum, tetraethyl sodium aluminum, triethylhydrolithium aluminum, diphenidihydrolithium aluminum, benzyltrihydrolithium aluminum and the like. .

Examples of M ² AlR _5-n X _n include pentaethyl magnesium aluminum, pentanormal butyl magnesium aluminum, tetraethyl methyl magnesium aluminum, tetraethyl chloro magnesium aluminum, benzyl diethyl dichloro magnesium aluminum, diphenyl trichloro magnesium aluminum, pentaethyl zinc aluminum, penta Examples thereof include ethyl beryllium aluminum, pentaethyl calcium aluminum, pentaethyl cadmium aluminum, ethyl tetrachloromagnesium aluminum and diethyl trihydromagnesium aluminum.

Examples of M ² (AlR _4-n H _n ) ₂ are bis (tetraethylaluminum) magnesium, bis (phenyltrihydroaluminum) magnesium, bis (tetrahydroaluminum) magnesium, bis (tetraethylaluminum) zinc, bis (tetraethylaluminum) Examples thereof include beryllium, bis (phenyltrihydroaluminum) calcium, bis (tetraethylaluminum) cadmium and the like.

Examples of M ² AlR _5-n (NR ₂ ) _n include diphenylaminotetraethylmagnesium aluminum, bis (diphenylamino) triethylmagnesium aluminum, diethylaminotriethylmagnesium aluminum, diphenylaminotetraethylzinc aluminum, bis (diphenylamino) triethylberyllium aluminum, Examples thereof include diethylaminotriethylcalcium aluminum, diethylaminotriethylcadmium aluminum and the like.

Examples of LiZnR _3-n (NR ₂ ) _n include diphenylaminodiethylzinc lithium, bis (diphenylamino) normal butylzinc lithium, and the like. Li ₂ ZnR _4-n (N
Examples of R ₂ ) _n include dinormal butyldiethyl zinc dilithium and diphenylamino dinormal butylethyl zinc dilithium.

Next, the polymerization temperature, which is the most important as a polymerization condition, needs to be higher than the boiling point of acrylonitrile at atmospheric pressure, and the higher the temperature, the more preferable it is from the viewpoint of improving stereoregularity. However, PAN is generally known to decompose and color at a temperature slightly lower than 200 ° C. Therefore, it is desirable to polymerize at a temperature lower than the temperature at which decomposition and color occur.

The polymerization solvent is not particularly limited as long as it is an organic solvent that does not inhibit the polymerization ability of the initiator, but an organic solvent containing an aromatic hydrocarbon group in its own molecule is preferable in order to further improve the isotactic fraction. . Although the polymerization mechanism in the method of the present invention has not been fully clarified yet, it is considered that the aromatic π electrons in the solvent molecule play some important role in the formation of stereoregularity of PAN. If these preferable solvents are listed, for example, benzene, toluene, orthoxylene, metaxylene, paraxylene, naphthalene, diphenyl ether, biphenyl and the like can be mentioned.

The polymerization initiator used in the present invention exerts its effect by increasing the polymerization temperature, but according to the study by the present inventors, not only the effect is exhibited by the temperature at the time of polymerization but also the stage at which it is not in contact with acrylonitrile. It has been found that the stereoregularity can be further improved by keeping the polymerization initiator of (1) at a high temperature. That is, it was found that the stereoregularity can be remarkably improved by giving the polymerization initiator a thermal history of at least 150 ° C. for 20 minutes or more prior to the polymerization.

The polymer obtained by the method of the present invention has a high stereoregularity and has significant features as described above, but the polymer after polymerization is a polar solvent which is a selective solvent for the low stereoregular acrylonitrile polymer. By extracting and removing the low stereoregular component, an acrylonitrile polymer having remarkably high stereoregularity can be obtained. This is considered to show the molecular weight distribution in which the polymer obtained by the method of the present invention is not narrow, and can be considered to support the fact that there are plural kinds of active species which initiate the polymerization. The solvent that can be used for this purpose is not particularly limited, and examples thereof include dimethylformamide, dimethylsulfoxide, dimethylacetamide, dimethylsulphone, succinonitrile, acetonitrile, and phenylenediamine.

Regarding the equipment for polymerizing at a temperature above the boiling point of acrylonitrile at atmospheric pressure, a concrete example will be described. To prevent acrylonitrile from evaporating and escaping to the outside of the system, as shown in FIG. An apparatus configured to cool and condense the vaporized components centering on acrylonitrile by a water-cooled or other suitable heat exchanger that can be cooled by another refrigerant and return them to the polymerization reaction system again (polymerization under reflux), or As shown in the figure, an apparatus in which acrylonitrile does not evaporate (polymerization under pressure) even at a temperature exceeding the boiling point of acrylonitrile under atmospheric pressure in the polymerization system itself is useful.

Here, the apparatus shown in FIGS. 1 and 2 will be described. First, in FIG. 1, 1 magnetically rotates the magnetic rotor 3 in the three-necked flask 5 to uniformly stir the inside of the reactor. 2 is a heat insulating material, 4 is an oil bath for adjusting the polymerization temperature to a constant value, and 6 is a dropping funnel for dropping acrylonitrile to be polymerized into the reaction system. Reference numeral 7 denotes a cooling pipe for cooling and condensing the components that have once evaporated and returning them to the reaction system. 8 is a nitrogen supply pipe, 9 is an exhaust pipe, 10
Is a liquid paraffin bath. The apparatus shown in FIG. 2 is exactly the same as the apparatus shown in FIG. 1 from 1 to 8, except that the pressure is adjusted by detecting the pressure in the reaction system and giving a signal to the pressure adjusting valve 12 so that the pressure is set. It is equipped with a vessel 11.

The solvent used in the method of polymerization under reflux usually needs to have a boiling point higher than that of acrylonitrile (77 ° C under atmospheric pressure). For example, heptane (98 ° C),
Cyclohexane (81 ° C), benzene (80 ° C), toluene (111 ° C), xylene (139 ° C, 145 ° C depending on the isomer structure)
℃), decalin (185 ℃, 193 ℃) and the like are used. However, depending on the case, it goes without saying that even if the solvent has a boiling point lower than that of acrylonitrile, the effect of the present invention can be exhibited if a facility capable of sufficiently cooling and refluxing the evaporated solvent from the polymerization reaction system is used. .

Gaseous supply of the acrylonitrile monomer to the reaction system during the polymerization under reflux is also effective in improving the stereoregularity of the produced PAN.

Further, in the case of polymerizing under pressure, in order to adjust the pressure in the reaction container by raising the temperature in a sealed reaction container, for example, a valve such as a needle valve is used to control the pressure in the reaction container to a predetermined value. When the pressure becomes higher than the pressure, the gas in the reaction vessel is withdrawn, and when the pressure becomes equal to or lower than the predetermined pressure, the valve is closed and a pressure adjustment mechanism designed to prevent the pressure in the reaction vessel from escaping outside the vessel can be used. Good. Even when using a solvent whose boiling point is not higher than that of acrylonitrile when polymerizing under pressure, by polymerizing by raising the boiling point of the solvent to a pressure that can raise the temperature above the polymerization temperature, difficulties such as polymerization under reflux, That is, there is an advantage that polymerization can be carried out without a special device such as cooling and condensation of a boiling solvent. Moreover, under pressure polymerization conditions, the molecular weight and yield of polyacrylonitrile are further improved.

The stereoregularity of the acrylonitrile polymer obtained by the method of the present invention is at least 0.35 or more in terms of isotactic fraction. This stereoregularity is usually an isotactic fraction of 0.25 to 0 for an acrylonitrile polymer with an industrialized redox catalyst or an acrylonitrile polymer with an anion polymerization catalyst known so far.
Compared to 26, it is significantly improved.

The isotactic fraction referred to here is the 13C-NMR (mass number 13) of a solution dissolved in deuterated dimethyl sulfoxide.
It is calculated from the peak intensity of the carbon of the cyano group of the nuclear magnetic resonance analyzer using the carbon isotope of More specifically, it is determined by peak identification based on the pentad tacticity attributed by the above-mentioned method described in Polymer Journal, Vol. 17, page 1291 (1985). That is,
In the 13 C-NMR nuclear magnetic resonance absorption peak chart, the ratio of the sum of the intensities of the three peaks mmmm, mmmr and rmmr to the total peak intensities is the isotactic fraction.

In this measurement, the absorption peak region of carbon in the cyano group (119 to 121) was used in order to increase the resolution and to provide the quantitative property.
ppm; standard of tetramethylsilane), and observe ± 500 Hz centering on the peak. JEOL Fourier transform NMR (FX-200) is used as the measuring device, deuterated dimethylsulfoxide is used as the solvent, and the sample concentration is adjusted to 3 to 20 weight percent. Measurement conditions are temperature 80 ℃, observation frequency width 1000Hz, data points
16k, irradiation time 6.5μs (45 ° pulse), pulse delay time
2.5a, sampling time 8.1s, total number of times 64 × 10 to 64 × 10
Set to 0.

For the viscosity average molecular weight in the present invention, the polymer to be measured is dissolved in dimethyl sulfoxide at 25 ° C., the intrinsic viscosity [η] is determined by a conventional method, and then the viscosity average molecular weight M is calculated by the following formula.

〔The invention's effect〕

Using the method of the present invention, an isotactic fraction of 0.35
As described above, an acrylonitrile polymer having a molecular weight of 10,000 or more and high stereoregularity can be produced industrially advantageously and efficiently.

This highly stereoregular acrylonitrile polymer has high crystallinity and has a characteristic that its melting point rises in the presence of water.
The fiber obtained from this polymer is excellent in mechanical strength and heat resistance in a wet state, and is useful, for example, in general clothing field, high-grade clothing field, industrial material field, space engineering field and the like.

Furthermore, since this acrylonitrile polymer has the property of selectively coordinating metal ions, it is useful as a material for selectively adsorbing metal, and the polymer coordinating the metal is a conductive polymer. Is also useful as

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 First set up to condense evaporative components and allow them to reflux
In the equipment as shown in the figure, first replace the nitrogen in a 300cc three-necked flask and add xylene (mixture of three isomers) to this.
After adding 50 cc of the solution to adjust the temperature to 120 ° C., 10 cc of a 1.0 molar heptane solution of dinormalhexylmagnesium as a polymerization initiator is added and left for 10 minutes. Next, 10 cc of acrylonitrile is dropped and polymerized for 60 minutes.

To this, an appropriate amount of a mixed solution of hydrochloric acid and methanol was added to terminate the polymerization reaction, and thereafter, after repeated filtration and washing with water, the result of dry weighing was 6.26 g.

This polymer was dissolved in deuterated dimethyl sulfoxide in an amount of 5% by weight and subjected to 13 C-NMR measurement, whereupon the isotactic fraction was 0.552. The viscosity average molecular weight (hereinafter simply referred to as molecular weight) was 60,000.

Table 1 shows the results of Example 1, the following Examples 2 to 14, and Comparative Examples 1 and 2.

Examples 2 and 3 and Comparative Examples 1 and 2 Polymerization was performed under the same apparatus and polymerization conditions as in Example 1 except that the polymerization temperature was changed to 100 ° C, 80 ° C, 70 ° C and 60 ° C. As shown in Table 1, it can be seen that the isotactic fraction improves at the boiling point of acrylonitrile.

Examples 4 to 14 Polymerization was carried out in the same apparatus as in Example 1 using various organometallic compounds as polymerization initiators. The same operation as in Example 1 was carried out except that the polymerization initiator and the solvent shown in Table 1 were used.

Example 15 to Example 22 Polymerization was performed using a combination of an organometallic compound and a fiber metal compound as a polymerization initiator. The results are shown in Table 2.

Examples 23 to 49 Polymerization was performed using an organomagnesium compound as a polymerization initiator. The results are shown in Tables 3 and 4.

Examples 50 to 64 Polymerization was carried out using a so-called Art Complex, which is a combination of two or more metals of Groups I, II and III of the Periodic Table, as a polymerization initiator. The results are shown in Table 5.

Examples 65 to 69 Polymerization was carried out in the same manner as in Example 1 except that the polymerization solvent was changed. The results are shown in Table 6.

Examples 70-72 Before using the organometallic compound as an initiator in the polymerization,
Polymerization was started after keeping the temperature at a high temperature for a certain period of time. The results are shown in Table 7.

Examples 73 to 76 100 g of the polymer produced in the same manner as in Example 1 was Soxhlet extracted with dimethylformamide for 6 hours to obtain 1.3 g of a polymer insoluble in dimethylformamide. Its isotactic fraction was 0.552 and its viscosity average molecular weight was 105,000.

Similarly, the extraction solvent was changed to polymerize. The results are shown in Table 8.

Example 77 In an apparatus as shown in FIG. 2 constructed so that the pressure of the whole reaction system could be adjusted, 50cc of xylene as a solvent and 1.0cc of a 1.0 mol toluene solution of dihexylmagnesium as a polymerization initiator were also added to a 300cc three-necked flask. After adding
After the entire polymerization system was replaced with nitrogen, the system was closed and the set value of the pressure regulator was given so that the gauge pressure was 2 atm. A metal fixture was used at the connecting portion between the glass appliances so that the connection would not be disconnected due to the pressure inside the device.

The reaction temperature was adjusted to 150 ° C with an oil bath equipped with a temperature control function. After adjusting to these conditions, 10cc of acrylonitrile was supplied by a dropping funnel to start the reaction,
It was polymerized for 60 minutes.

The polymer obtained had an isotactic fraction of 0.592 and a viscosity average molecular weight of 88,600.

[Brief description of drawings]

FIG. 1 is an example of an apparatus used for implementing the present invention, and FIG. 2 is another example of an apparatus used for implementing the present invention. In Figures 1 and 2, 1: magnetic rotor, 2: heat insulator, 3: magnetic rotor, 4: oil bath with adjustable temperature, 5: three-necked flask, 6: dropping funnel, 7: cooling Pipe, 8: nitrogen supply pipe, 9: exhaust pipe, 10: liquid paraffin bath, 11: pressure regulator, 12: pressure regulating valve.

Claims (12)

[Claims] 1. When polymerizing acrylonitrile in an organic solvent, an organometallic compound is used alone or in combination with a transition metal compound as an initiator to polymerize at a temperature exceeding the boiling point of acrylonitrile at atmospheric pressure. And a method for producing a stereoregular acrylonitrile polymer. 2. The method for producing a stereoregular acrylonitrile polymer according to claim 1, wherein an organometallic compound containing an alkaline earth metal is used as the metal portion. 3. An organometallic compound represented by the formula R ₂ Mg, RMgX, R ₂ NM
gR, R ₂ NMgNR ₂ , (R ₃ Si) ₂ NMgR, (R ₃ Si) ₂ NMgN (SiR ₃ ) ₂ , R
_The method for producing a stereoregular acrylonitrile polymer according to claim 2, wherein at least one selected from the magnesium compounds represented by ₃ SiMgR, R ₃ SiMgSiR ₃ , ROMgR, ROMgOR, RSMgR and RSMgSR is used. Here, R in each formula, which may be the same or different from each other, is a hydrocarbon group composed of an aliphatic or aromatic hydrocarbon or a combination thereof, X is halogen, and R ₂ In the compound represented by NMgR and R ₂ NMgNR ₂ , _two Rs represented by R ₂ may be bonded to each other to form a heterocycle with the nitrogen atom to which they are bonded. 4. The method for producing a stereoregular acrylonitrile polymer according to claim 2, wherein at least one selected from the beryllium compounds represented by the formulas R ₂ Be and RBeX is used as the organometallic compound. Here, R in the formula R ₂ Be may be the same or different from each other, each is a hydrocarbon group composed of an aliphatic or aromatic hydrocarbon or a combination thereof, and X is halogen. 5. The method for producing a stereoregular acrylonitrile polymer according to claim 2, wherein at least one selected from the calcium compounds represented by the formulas R ₂ Ca and RCaX is used as the organometallic compound. Here, R in the formula R ₂ Ca may be the same or different, and each is an aliphatic or aromatic hydrocarbon or a hydrocarbon consisting of a combination thereof, and X is halogen. 6. An organometallic compound having a periodic table of I, II and III.
The method for producing a stereoregular acrylonitrile polymer according to claim 1, wherein an organometallic compound that simultaneously contains two kinds of different metals among group metals is used. 7. An organometallic compound of the formula M ¹ M ² R _3-n H _n , M ¹ AlR
_4-n H _n , M ² AlR _5-n X _n , M ² (AlR _4-n H _n ) ₂ , M ² AlR _5-n (NR ₂ ) _n ,
The production of a stereoregular acrylonitrile polymer according to claim 6, wherein at least one selected from the organometallic compounds represented by LiZnR _3-n (NR ₂ ) _n and Li ₂ ZnR _4-n (NR ₂ ) _n is used. Method. Here, R in each formula may be the same or different and is a hydrocarbon group composed of an aliphatic or aromatic hydrocarbon or a combination thereof. Further, M ¹ is a kind of metal selected from lithium, sodium and potassium, M ² is magnesium, beryllium, calcium,
One kind of metal selected from zinc and cadmium, X is one kind of element selected from fluorine, chlorine, bromine and iodine, and n is zero or a positive integer and is 5-n in the same molecule. , 4-n or 3-n takes a value in a range that does not become negative. 8. The method for producing a stereoregular acrylonitrile polymer according to claim 1, wherein an organic compound having an aromatic hydrocarbon group in its molecule is used as a polymerization solvent. 9. A polymerization initiator as a polymerization initiator in a solvent to be polymerized.
The method for producing a stereoregular acrylonitrile polymer according to claim 1, wherein the polymer is given a heat history of 20 minutes or more at a temperature of 0 ° C. or more and then polymerized at a predetermined temperature. 10. The method for producing a stereoregular acrylonitrile polymer according to claim 1, wherein only a portion having low stereoregularity is extracted and removed from the obtained polymer with a polar solvent to further enhance the stereoregularity of the polymer. 11. The method for producing a stereoregular acrylonitrile polymer according to claim 1, wherein components evaporated from the polymerization reaction system are cooled and condensed and returned to the polymerization reaction system again. 12. The method for producing a stereoregular acrylonitrile polymer according to claim 1, wherein the polymerization is carried out under the condition that the pressure during the polymerization is higher than the atmospheric pressure.