JPH04314709A - Production of styrenic polymer - Google Patents

Abstract

PURPOSE:To produce a styrenic polymer having a high syndiotacticity economically and efficiently. CONSTITUTION:A styrenic polymer having a high syndiotacticity is produced by polymerizing a styrenic monomer in the presence of a catalyst comprising an aluminoxane having a 2-8C alkyl group, a methylated organoaluminum compd., and a transition metal compd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a styrenic polymer, and more particularly to a method for efficiently producing a styrenic polymer having a highly syndiotactic stereochemical structure in the polymer chain.

0002

[Prior art and problems to be solved by the invention] Conventionally,
In producing a styrenic polymer having a syndiotactic structure by polymerizing a styrenic monomer, (A)
It is known to use a catalyst consisting of a titanium compound and (B) a contact product of an organoaluminum compound and water (Japanese Patent Application Laid-Open No. 187708/1984, etc.). In the above catalyst, a contact product of trimethylaluminum and water is used as a particularly effective component (B), but since the raw material trimethylaluminum is expensive, the catalyst cost is extremely high. Ta. However, when a part of this trimethylaluminum is replaced with other alkylaluminum, there is a problem that the polymerization activity decreases. Furthermore, the reaction between trimethylaluminum and water is extremely violent, making it extremely difficult to synthesize.

[0003] Therefore, the present inventor has conducted extensive research in order to develop a method for producing styrenic polymers having a highly syndiotactic structure at low cost and more efficiently.

0004

[Means for solving the problem] As a result, by using a combination of an organometallic compound having a methyl group and a transition metal compound, an alkyl group other than a methyl group that can be synthesized more cheaply, easily, and safely than methylaluminoxane. It has been found that sufficient activity can be expressed even when using an aluminoxane having the following. The present invention was completed based on this knowledge.

That is, the present invention combines a styrene monomer with (a) an aluminoxane having an alkyl group having 2 to 8 carbon atoms, (b) an organometallic compound having a methyl group, and (c
) A method for producing a styrenic polymer having a highly syndiotactic structure characterized by polymerization in the presence of a catalyst made of a transition metal compound.

The catalyst used in the method of the present invention is composed of components (a), (b) and (c) as described above.
Here, component (a) is an aluminoxane having an alkyl group having 2 to 8 carbon atoms. This aluminoxane is generally a product of contact between a trialkylaluminum consisting of an alkyl group having 2 to 8 carbon atoms and water, and there are various methods for bringing the trialkylaluminum and water into contact at this time. For example, the following three can be mentioned. Namely, ■ a method in which trialkylaluminum is dissolved in an organic solvent and brought into contact with water or steam; ■ a method in which water is dissolved in an organic solvent and trialkylaluminum is added thereto; and ■ a method in which the metal is dissolved in water. Examples include a method of using crystallization water contained in salts or the like, water adsorbed to inorganic substances or organic substances, and bringing trialkylaluminum into contact with this water.

[0007] Component (a) of the catalyst of the present invention may be an aluminoxane synthesized by the above method as it is, or a concentrated or dried aluminoxane. When concentrating or drying, the temperature is usually 0 to 200°C, preferably 10°C.
~150°C and the pressure may be selected from atmospheric pressure to reduced pressure. The organic solvent may be appropriately selected from saturated hydrocarbons and aromatic hydrocarbons.

Next, component (b) of the catalyst of the present invention is an organometallic compound having a methyl group, preferably an aluminum compound, a zinc compound, etc. having a methyl group. Among these, aluminum compounds having a methyl group are particularly preferred, and trimethylaluminum is especially optimal. Other examples include monomethyldichloroaluminum, dimethylmonochloroaluminum, monomethyldibromoaluminum, dimethylmethoxyaluminum, dimethylbromoaluminum, methyldimethoxyaluminum, dimethylethylaluminum, methyldiethylaluminum, and the like.

Furthermore, the component (c) of the catalyst of the present invention is a transition metal compound, such as a titanium compound, a zirconium compound, or a hafnium compound, etc.
Mention may be made of transition metal compounds of group B. Among them, titanium compounds are most preferred. There are various types of titanium compounds. For example, the general formula Ti R1 a R2 b R3 c R4 4-(a
+b+c) ...(I) or Ti R1 d R2 e R3 3-(d+e)
...(II) [wherein, R1 , R
2, R3 and R4 are each hydrogen atom, carbon number 1
~20 alkyl group, alkoxy group having 1 to 20 carbon atoms,
Aryl group having 6 to 20 carbon atoms, alkylaryl group, arylalkyl group, acyloxy group having 1 to 20 carbon atoms,
Indicates a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, or a halogen atom. a, b,
c each represents an integer of 0 to 4, and d and e each represent an integer of 0 to 3. ] is at least one compound selected from the group consisting of titanium compounds and titanium chelate compounds. R1, R2, R3 and R4 in this general formula (I) or (II) are a hydrogen atom, an alkyl group having 1 to 20 carbon atoms (specifically, a methyl group, an ethyl group, a propyl group, a butyl group, amyl group, isoamyl group, isobutyl group, octyl group, 2-ethylhexyl group), alkoxy groups having 1 to 20 carbon atoms (specifically methoxy group, ethoxy group, propoxy group, butoxy group, amyloxy group, hexyloxy group) , phenoxy group, 2-ethylhexyloxy group, etc.), carbon number 6-20
Aryl group, alkylaryl group, arylalkyl group (specifically phenyl group, tolyl group, xylyl group, benzyl group, etc.), acyloxy group having 1 to 20 carbon atoms (specifically heptadecylcarbonyloxy group, etc.) , cyclopentadienyl group, substituted cyclopentadienyl group (specifically methylcyclopentadienyl group, 1,2-dimethylcyclopentadienyl group, pentamethylcyclopentadienyl group, etc.), indenyl group or halogen Indicates an atom (chlorine, bromine, iodine, fluorine). These R1
, R2 , R3 and R4 are the same,
They may be different. Furthermore, a, b, and c each represent an integer of 0 to 4, and d and e each represent an integer of 0 to 3.
indicates an integer.

Specific examples of the tetravalent titanium compound and titanium chelate compound represented by the general formula (I) include methyl titanium trichloride, titanium tetramethoxide, titanium tetraethoxide, titanium monoisopropoxy trichloride, Titanium diisopropoxy dichloride, titanium triisopropoxy monochloride, tetra(2-ethylhexyloxy) titanium, cyclopentadienyl titanium trichloride, biscyclopentadienyl titanium dichloride, cyclopentadienyl titanium trimethoxide, cyclopentadi enyltrimethyltitanium, pentamethylcyclopentadienyltitanium trimethoxide, pentamethylcyclopentadienyltrimethyltitanium, titanium tetrachloride, titanium tetrabromide, bis(
Examples include 2,4-pentanedionato) titanium oxide, bis(2,4-pentanedionato) titanium dichloride, and bis(2,4-pentanedionato) titanium dibutoxide.

[0011] When using the above catalyst, the ratio of each component used varies depending on various conditions and cannot be unambiguously determined, but usually component (a): component (b) = 50
:1 to 1:50 (aluminum atomic ratio), preferably 2
It is 0:1 to 1:20 (aluminum atomic ratio), more preferably 10:1 to 1:10 (aluminum atomic ratio).

The raw material monomer used in the method of the present invention is a styrene monomer, specifically styrene;
-Methylstyrene; m-methylstyrene; o-methylstyrene; 2,4-dimethylstyrene; 2,5-dimethylstyrene; 3,4-dimethylstyrene; 3,5-dimethylstyrene; p-ethylstyrene; m-ethyl Styrene; alkylstyrene such as p-tert-butylstyrene, p-divinylbenzene; m-divinylbenzene;
trivinylbenzene; p-chlorostyrene; m-chlorostyrene; o-chlorostyrene; p-bromostyrene;
Halogenated styrenes such as m-bromostyrene; o-bromostyrene; p-fluorostyrene; m-fluorostyrene; o-fluorostyrene; o-methyl-p-fluorostyrene, etc., or a mixture of two or more of these can give.

In order to produce a styrenic polymer by the method of the present invention, styrenic monomers are polymerized (or Copolymerization), but this polymerization may be carried out in bulk, and is carried out in aliphatic hydrocarbons such as pentane, hexane, heptane, alicyclic hydrocarbons such as cyclohexane, or aromatic hydrocarbons such as benzene, toluene, xylene, etc. Good too. The polymerization temperature is not particularly limited, but is generally -30°C to +120°C, preferably -10°C to +1
It is 00℃. Furthermore, in order to control the molecular weight of the obtained styrenic polymer, it is effective to carry out the polymerization reaction in the presence of hydrogen.

The styrenic polymer thus obtained has a highly syndiotactic structure. Here, the highly syndiotactic structure in styrenic polymers refers to a highly syndiotactic structure in which the stereochemical structure is highly syndiotactic, i.e., a phenyl group or substituted side chain with respect to the main chain formed from carbon-carbon bonds. This means that the phenyl groups have a three-dimensional structure in which they are alternately positioned in opposite directions, and its tacticity is determined by the nuclear magnetic resonance method (nuclear magnetic resonance method) using carbon isotopes.
13C-NMR method). 13C-NMR
The tacticity measured by the method can be expressed by the abundance ratio of a plurality of consecutive constituent units, for example, a dyad if there are two units, a triad if there are three units, and a pentad if there are five units. The term "styrenic polymer having a highly syndiotactic structure" as referred to in 2012 generally refers to 75% or more in dyads, preferably 85% or more in dyads, or 30% in pentads (racemic pentads).
Polystyrene, poly(alkylstyrene), preferably having a syndiotacticity of 50% or more,
It means poly(halogenated styrene), poly(alkoxystyrene), poly(vinylbenzoic acid ester), mixtures thereof, or copolymers containing these as main components.In addition, poly(alkylstyrene) here refers to Poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene), etc. Poly(halogenated styrene) includes poly(chlorostyrene), poly(bromostyrene), Poly(fluorostyrene) etc.Also, poly(fluorostyrene) etc.
Examples of the alkoxystyrene include poly(methoxystyrene) and poly(ethoxystyrene). Among these, particularly preferred styrenic polymers are:
Polystyrene, poly(p-methylstyrene), poly(m
-methylstyrene), poly(p-tert-butylstyrene), poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene), and even combinations of styrene and p-methylstyrene. Polymers can be mentioned.

The styrenic polymer produced by the method of the present invention generally has a number average molecular weight of 1,000 to 5,0.
00,000, preferably 50,000 to 4,000
0,000 and has high syndioctality as mentioned above. After polymerization, if necessary, it is decalcified with a washing solution containing hydrochloric acid, etc., and then washed and dried under reduced pressure to produce methyl ethyl ketone, etc. By washing with a solvent to remove soluble components and further treating the resulting insoluble components with chloroform or the like, a highly purified styrenic polymer with extremely high syndiotacticity can be obtained.

[0016]

【Example】

Example 1 (1) Preparation of aluminoxane In a glass container with an internal volume of 1 liter that was purged with argon,
200 ml of toluene and 29.7 g (150 mmol) of triisobutylaluminum were added, cooled to 5° C., and 2.43 g (135 mmol) of deoxygenated water was slowly added dropwise. Thereafter, the obtained solution was heated at 50°C under reduced pressure.
While stirring, toluene was distilled off to obtain 17.91 g of aluminoxane. (2) Polymerization of styrene In a nitrogen-substituted container, add 10 ml of styrene, 150 micromoles of trimethylaluminum, and add 20% of the aluminoxane obtained in (1) above as aluminum atoms.
0 micromoles and 10 micromoles of pentamethylcyclopentadienyl titanium trimethoxide were added to give 70%
The polymerization reaction was carried out at ℃ for 1 hour. After the reaction was completed, the product was washed with a hydrochloric acid/methanol mixture to separate and remove the catalyst component, and dried to obtain 2.83 g of a polymer (polystyrene). The racemic pentad syndiotacticity of this polymer was 92% by 13C-NMR measurement. (3) Polymerization of styrene In a nitrogen-substituted container, 10 ml of styrene, 150 micromoles of trimethylaluminum, 100 micromoles of triisobutylaluminum, 200 micromoles of the aluminoxane obtained in (1) above as aluminum atoms, and pentamethylcyclopenta 40 micromoles of dienyl titanium trimethoxide was added, and polymerization was carried out at 70°C for 1 hour. After the reaction was completed, the product was washed with a hydrochloric acid/methanol mixture to separate and remove the catalyst component, and dried to obtain 2.83 g of a polymer. The racemic pentad syndiotacticity of this polymer was 92% by 13C-NMR measurement.

Comparative Example 1 Polymerization of styrene Polymerization was carried out in the same manner as in Example 1 (2) except that trimethylaluminum was not used.
Obtained 0g.

Example 2 (1) Preparation of aluminoxane solution In 10 ml of toluene, 10 mmol of aluminum atoms of the aluminoxane synthesized in Example 1 (1) and 5 mmol of trimethylaluminum were dissolved. (2) Polymerization of styrene In a nitrogen-substituted container, 10 ml of styrene, 20 micromoles of trimethylaluminum, and 20 micromoles of aluminoxane obtained in (1) above as aluminum atoms.
0 micromol and 40 micromol of pentamethylcyclopentadienyl titanium trimethoxide were added,
The polymerization reaction was carried out at ℃ for 1 hour. After the reaction was completed, the product was washed with a hydrochloric acid/methanol mixture to separate and remove the catalyst component, and dried to obtain 3.44 g of a polymer (polystyrene). The racemic pentad syndiotacticity of this polymer was 92% by 13C-NMR measurement.

Example 3 (1) Preparation of aluminoxane In a 500 ml container purged with nitrogen, 2 toluene was added.
00ml, copper sulfate pentahydrate 6.5g (0.02
6 mol) and cooled on ice. Next, add toluene to 33 ml (0.13 mol) of triisobutylaluminum, dilute to 50 ml, and add 33 ml with a dropping funnel.
It was added dropwise into the container over 0 minutes. The temperature was controlled at 7° C. or below, and after the dropwise addition, it was maintained at 20° C. and left under nitrogen for 24 hours. Thereafter, the solid component was filtered off, and the solution was dried in vacuo to remove toluene, yielding 13.66 g of aluminoxane. (2) Polymerization of styrene In Example 1 (3), the above (
Styrene was polymerized in the same manner as in Example 1 (3), except that the aluminoxane obtained in 1) was used, and 2.74 g of a polymer (polystyrene) was obtained.

[0020]

As described above, the catalyst used in the method of the present invention is inexpensive and has extremely high activity. Therefore, by polymerizing a styrenic monomer according to the method of the present invention, a styrenic polymer with high syndiotacticity can be produced economically and efficiently. The styrenic polymer having a syndiotactic structure thus obtained has excellent physical properties such as heat resistance and chemical resistance, and is widely and effectively used in a variety of applications.

Claims (2)

[Claims] Claim 1: A styrenic monomer having (a) 2 carbon atoms;
A styrenic system having a highly syndiotactic structure, which is polymerized in the presence of a catalyst consisting of an aluminoxane having ~8 alkyl groups, (b) an organometallic compound having a methyl group, and (c) a transition metal compound. Method for producing polymers. 2. The method for producing a styrenic polymer according to claim 1, wherein (b) the organometallic compound having a methyl group is an aluminum compound having a methyl group.