JPH0813851B2 - Method for producing styrene polymer and its catalyst - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a styrene-based polymer and a catalyst used in the method, and more specifically, the stereochemical structure of the polymer chain mainly has a syndiotactic structure. The present invention relates to a method for efficiently producing a styrene polymer and a catalyst used in the method.

[Problems to be Solved by Prior Art and Invention]

Conventionally, when a styrene-based polymer having a syndiotactic structure is produced by polymerizing styrene or a styrene derivative, a catalyst composed of (A) a titanium compound and (B) a contact product of an organic aluminum compound and water is used. Is known (JP-A-62-187708).

In the above catalyst, a contact product of trimethylaluminum and water is used as the component (B),
Since trimethylaluminum as a raw material is expensive, there is a drawback that the catalyst cost is very high. However, when a part of this trimethylaluminum is replaced with another linear alkylaluminum, there is a problem that the polymerization activity is lowered.

Therefore, the inventors of the present invention have conducted extensive studies mainly to develop a method for more efficiently producing a styrene-based polymer having a syndiotactic structure and an inexpensive and highly active polymerization catalyst.

[Means for solving the problem]

As a result, they have found that the above problems can be solved by using a specific organoaluminum compound in combination with trimethylaluminum as a raw material of the component (B). The present invention has been completed based on such findings.

That is, the present invention provides (A) a titanium compound and (B)
In a catalyst for producing a styrene-based polymer, which comprises an organoaluminum compound and a contact product of water, trimethylaluminum and a general formula AlR ₃ are used as a contact product of the organoaluminum compound (B) and water. , R represents a branched alkyl group having 3 to 10 carbon atoms. ] Tri-branched alkylaluminum represented by 99.9: 0.1 ~
It is intended to provide a catalyst for producing a styrene polymer, which is characterized by using a contact product of an organoaluminum compound having a molar ratio of 50:50 and water.

The catalyst of the present invention contains the above-mentioned components (A) and (B) as main components, and there are various titanium compounds as the component (A). For example, the general formula TiR ¹ _a R ² _b R ³ _c R ⁴ _{4- (a + b + c)} ... (I) or TiR ¹ _d R ² _e R ³ _{3- (d + e)} ... (II ) [In the formula, R ¹ , R ² , R ³ and R ⁴ are a hydrogen atom and a carbon number 1 respectively.
To alkyl group having 1 to 20 carbon atoms, 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, cyclopentadienyl group, substituted cyclopenta Indicates a dienyl group, an indenyl group or a halogen atom. a, b, and c each represent an integer of 0 to 4, and d and e each represent an integer of 0 to 3. ] At least one compound selected from the group consisting of titanium compounds and titanium chelate compounds represented by:

R ¹ , R ² , R ³ and R ⁴ in the general formula (I) or (II) are each a hydrogen atom, an alkyl group having 1 to 20 carbon atoms (specifically, a methyl group, an ethyl group, a propyl group, Butyl group, amyl group, isoamyl group, isobutyl group, octyl group, 2-ethylhexyl group, etc., alkoxy group 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.), 6 to 20 carbon atoms
Aryl group, alkylaryl group, arylalkyl group (specifically, phenyl group, tolyl group, xylyl group, benzyl group, etc.), C1-20 acyloxy group (specifically, heptadecylcarbonyloxy group, etc.) , Cyclopentadienyl group, substituted cyclopentadienyl group (specifically, methylcyclopentadienyl group, 1,2-dimethylcyclopentadienyl group, pentamethylcyclopentadienyl group, etc.), indenyl group or halogen atom (Chlorine, bromine, iodine, fluorine) is shown. These R ¹ , R ² , R ³ and R ⁴
May be the same or 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.

Specific examples of the tetravalent titanium compound and the titanium chelate compound represented by the general formula (I) include methyltitanium trichloride, titanium tetramethoxide, titanium tetraethoxide, titanium monoisopropoxy trichloride, titanium diisotate. Propoxy dichloride, titanium triisopropoxy monochloride, tetra (2-ethylhexyloxy) titanium, cyclopentadienyl titanium trichloride, biscyclopentadienyl titanium dichloride, cyclopentadienyl titanium trimethoxide, cyclopentadienyl trimethyl titanium , Pentamethylcyclopentadienyltitanium trimethoxide, pentamethylcyclopentadienyltrimethyltitanium, titanium tetrachloride Titanium tetrabromide, bis (2,4
Pentane dionato) titanium oxide, bis (2,
4-pentanedionato) titanium dichloride, bis (2,4-pentanedionato) titanium dibutoxide and the like can be mentioned. As the titanium compound of the component (A), other than the above, [In the formula, R ⁵ and R ⁶ are each a halogen atom and a carbon number of 1 to 20.
And an alkoxyl group and an acyloxy group, and k is 2 to 20. ] A condensed titanium compound represented by the following may be used.

Further, the titanium compound may be used in the form of a complex with an ester or ether. The trivalent titanium compound represented by the general formula (II), which is another type of the component (A), is typically titanium trihalide such as titanium trichloride, cyclopentadienyl such as cyclopentadienyl titanium dichloride. Examples thereof include titanium compounds, and those obtained by reducing tetravalent titanium compounds. These trivalent titanium compounds may be used in the form of a complex with an ester or ether.

On the other hand, as the component (B) which constitutes the main component of the catalyst together with the above-mentioned titanium compound component (A), trimethylaluminum and the general formula AlR ₃ (IV) [wherein, R has 3 to 10 carbon atoms] A branched alkyl group is shown. ] A contact product of a tri-branched alkylaluminum represented by the following formula and water is used. In the above general formula (IV), R
Is a branched alkyl group having 3 to 10 carbon atoms, for example, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, 2-methylpentyl group, 2
-Methylhexyl group, 2-ethylhexyl group and the like, and the tri-branched alkylaluminum represented by the general formula (IV) is specifically triisopropylaluminum, triisobutylaluminum, tritert-butylaluminum, triisopentylaluminum, Tri (2-methylpentyl) aluminum, tri (2-methylhexyl)
Examples thereof include aluminum and tri (2-ethylhexyl) aluminum, and among them, triisobutylaluminum is preferable.

In preparing the contact product which is the component (B),
Trimethylaluminum and tri-branched alkylaluminum represented by the general formula (IV) can be used in various ratios, but generally trimethylaluminum: tribranched alkylaluminum = 99.9: 0.1 to 50:50 (molar ratio), preferably Used together at a ratio of 98: 2 to 75:25 (molar ratio). If the proportion of tri-branched alkylaluminum is too large, the resulting contact product with water will be insoluble in the hydrocarbon solvent as the polymerization solvent, and sufficient activity will not be expressed. Conversely, if the proportion of tri-branched alkylaluminum is small,
A large amount of trimethylaluminum is used, which is economically disadvantageous, and at the same time, the activity is insufficiently improved.

The component (B) of the catalyst of the present invention is a contact product of trimethylaluminum and tribranched alkylaluminum and water as described above, and the water here is ordinary water, ice or various water-containing compounds such as water. Solvent-saturated water, adsorbed water of inorganic substances, or water of crystallization containing metal salts such as CuSO ₄ .5H ₂ O is used.

The contact product of trimethylaluminum and tri-branched alkylaluminum with water can be prepared by various methods. For example, trimethylaluminum and tribranched alkylaluminum are dissolved in an organic solvent and then contacted with water. In the method, trimethylaluminum and tri-branched alkylaluminum are initially added at the time of polymerization, and water is added later, and further, crystallization water contained in metal salts, etc., and adsorbed water to inorganic and organic substances are trimethylaluminum and tri-branched. There is a method of reacting with alkylaluminum.

The catalyst of the present invention contains the above-mentioned components (A) and (B) as main components, and in addition to the above, if desired, a catalyst component such as a general formula AlR ⁷ ₃ [wherein R ⁷ is a carbon number 1 ~ 8 alkyl groups are shown. ] It is also possible to add a trialkylaluminum represented by the following formula and other organometallic compounds. When this catalyst is used, the ratio of the component (A) to the component (B) in the catalyst varies depending on various conditions and cannot be uniquely determined, but normally (B) is different from aluminum in the component ( The ratio to titanium in component A), that is, aluminum / titanium (molar ratio), is 1 to 10 ⁶ , preferably 10 to 10 ⁴ .

The catalyst of the present invention as described above exhibits high activity mainly in the production of a styrene polymer having a syndiotactic structure.

Therefore, the present invention further provides a method for producing a styrenic polymer using the above catalyst.

To produce a styrenic polymer by the method of the present invention, styrene and / or a styrene derivative (alkylstyrene, alkoxystyrene, halogenated compound) is prepared in the presence of a catalyst containing the above-mentioned components (A) and (B) as a main component. Styrene-based monomers such as styrene and vinyl benzoate) are polymerized (or copolymerized), but this polymerization may be in bulk, and aliphatic hydrocarbons such as pentane, hexane and heptane, and alicyclic hydrocarbons such as cyclohexane. Alternatively, it may be carried out in an aromatic hydrocarbon solvent such as benzene, toluene or xylene. The polymerization temperature is not particularly limited, but is generally -30 ° C to + 120 ° C, preferably -10 ° C to + 100 ° C.

Further, in order to control the molecular weight of the obtained styrene polymer, it is effective to carry out the polymerization reaction in the presence of hydrogen.

The styrene-based polymer thus obtained mainly has a syndiotactic structure. here,
The predominantly syndiotactic structure in a styrene-based polymer means that the stereochemical structure is predominantly a syndiotactic structure, that is, a phenyl group or a substituted phenyl group, which is a side chain with respect to the main chain formed from carbon-carbon bonds, alternates. It means that it has a three-dimensional structure located in the opposite direction, and its tacticity is based on the nuclear magnetic resonance method ( ¹³ C-N
MR method). Tacticity measured by the ¹³ C-NMR method can be indicated by the existence ratio of a plurality of continuous constitutional units, for example, two diads, three triads, and five pentads. However, the "predominantly styrene-based polymer having a syndiotactic structure" in the present invention is usually a diad.
Polystyrene, poly (alkylstyrene), poly (halogenated styrene), poly having a syndiotacticity of 75% or more, preferably 85% or more, or pentad (racemic pentad) of 30% or more, preferably 50% or more (Alkoxystyrene), poly (vinylbenzoic acid ester) and mixtures thereof, or copolymers containing these as the main components, wherein poly (alkylstyrene) means poly (methylstyrene),
There are poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene), etc.,
Examples of poly (halogenated styrene) include poly (chlorostyrene), poly (bromostyrene), and poly (fluorostyrene). Also, poly (alkoxystyrene)
Examples thereof include poly (methoxystyrene) and poly (ethoxystyrene). Of these, particularly preferable styrene polymers include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), and poly (p-
Examples thereof include tertiary butyl styrene), poly (p-chlorostyrene), poly (m-chlorostyrene), poly (p-fluorostyrene), and a copolymer of styrene and p-methylstyrene.

The styrenic polymer produced by the method of the present invention,
Generally a number average molecular weight of 1,000 to 5,000,000, preferably 50,0
00 to 4,000,000, which has a high syndioctacity as described above, but after polymerization, if necessary, deashing with a washing liquid containing hydrochloric acid, etc., and further washing and drying under reduced pressure, such as methyl ethyl ketone If the soluble matter is removed by washing with the solvent described above and the obtained insoluble matter is further treated with chloroform or the like, a high-purity styrene polymer having extremely large syndiotacticity can be obtained.

〔Example〕

 Next, the present invention will be described in more detail with reference to examples.

Example (1) Preparation of contact product of aluminum compound and water In a glass container having an inner volume of 500 ml and purged with argon, 200 ml of toluene and 23.7 g (95 mmol) of copper sulfate pentahydrate (CuSO ₄ .5H ₂ O) were added. Then, 21.5 ml (225 mmol) of trimethylaluminum and 6.3 ml (25 mmol) of triisobutylaluminum were added and reacted at 40 ° C. for 24 hours.

Then, from the solution obtained by removing the solid components, heat treatment was further performed at 110 ° C. for 2 hours under reduced pressure to obtain 6.12 g of a colorless solid (contact product). This was dissolved in 50 ml of toluene to obtain a catalyst solution.

(2) Polymerization of styrene In a reaction vessel having an internal volume of 500 ml, 25 ml of heptane, the above (1)
6 mmol of the contact product obtained as described in 1. above as an aluminum atom, 12 × 10 ⁻³ mmol of pentamethylcyclopentadienyltitanium trimethoxide and 225 ml of styrene were added, and a polymerization reaction was carried out at 70 ° C. for 3 hours.

After completion of the reaction, the product was washed with a hydrochloric acid-methanol mixed solution to decompose and remove the catalyst component, and dried to obtain 48.1 g of a polymer. The polymerization activity was 297 g / g · Al. The syndiotacticity of this polymer in racemic pentad is ^13C -NMR.
From the measurement, it was found to be 96%.

Examples 2 to 4 and Comparative Examples 1 to 3 (1) Preparation of Contact Product of Aluminum Compound and Water In Example 1 (1), the amount of trimethylaluminum was changed and 6.3 ml of triisobutylaluminum (25
Mmol) in place of the predetermined amount of aluminum compound shown in the table, the same operation as in Example 1 (1) was carried out to obtain a contact product, which was dissolved in toluene to obtain a catalyst solution. And

(2) Polymerization of styrene Except that the catalyst solution obtained in (1) above was used,
A polymer (polystyrene) was obtained in the same manner as in Example 1 (2). The results are shown in the table.

[Effects of the Invention] As described above, the catalyst of the present invention is less expensive and has a significantly higher activity than the catalyst using only trimethylaluminum as the organoaluminum compound in the contact product with water. Therefore, when a styrene-based monomer is polymerized using this catalyst, a styrene-based polymer having high syndiotacticity can be produced economically advantageously and efficiently.

The syndiotactic styrene-based polymer thus obtained has excellent physical properties such as heat resistance and chemical resistance, and is widely and effectively used in various applications.

Claims (4)

[Claims] 1. A catalyst for producing a styrene-based polymer comprising (A) a titanium compound and (B) an organoaluminum compound and a contact product of water, wherein the organoaluminum compound (B) is contacted with water. As products, trimethylaluminum and general formula AlR ₃ [wherein R represents a branched alkyl group having 3 to 10 carbon atoms]. ] Tri-branched alkylaluminum represented by 99.9: 0.1 ~
A catalyst for producing a styrene-based polymer, which uses a contact product of an organoaluminum compound having a molar ratio of 50:50 and water. 2. A catalyst according to claim 1, wherein the tri-branched alkylaluminum is triisobutylaluminum. 3. A method for producing a styrene-based polymer, which comprises using the catalyst according to claim 1 or 2 for polymerizing styrene and / or a styrene derivative. 4. The styrene-based polymer is a styrene-based polymer mainly having a syndiotactic structure.
The manufacturing method described.