JPH09183810A - Production of syndiotactic polystyrene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a syndiotactic polystyrene having high heat stability and a syndiotactic structure at a high yield by using a specific titanium-based compound as a catalyst. SOLUTION: (A) A titanium-based compound having a piece of (substituted) cyclopentadienyl and expressed by CpTiF3 [Cp is a (substituted) cyclopentadienyl; F is a fluorine atom] (e.g. cyclopentadienyltitanium trifluoride) is used as a catalyst, (B) trimethylaluminum or a condensation product of an organic aluminum containing trimethylaluminum as a main component with water is used as a promoter and (C) styrene or a styrene derivative is polymerized. For instance, a molar ratio of (the aluminum in the component B)/(the titanium in the component A) is made to (150/1)-(500/1) and the polymerization is performed at 25-90 deg.C for 1-10hrs.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for efficiently producing crystalline syndiotactic polystyrene or a derivative thereof starting from styrene or a derivative thereof.

[0002]

2. Description of the Related Art Styrene or a derivative thereof is produced by using a titanium compound as a catalyst, trimethylaluminum or a condensate of trimethylaluminum-based organic aluminum and water (usually referred to as methylaluminoxane (abbreviated as MAO)) as a co-catalyst. It is well known to obtain syndiotactic polystyrene or derivatives thereof by polymerizing. For example, JP-A-62-18770
No. 8 discloses a styrene-based polymer characterized by using a contact product of (A) a titanium compound and (B) an organoaluminum compound and a condensing agent as a catalyst component in polymerizing styrene or a styrene derivative. Manufacturing methods have been proposed.

Further, the titanium compound has a general formula of TiR ¹ _a R ² _b R ³ _c X ¹ _{4- (a + b + c)} or TiR ¹ _d R ² _e X ¹ _{3- (d + e)} [wherein , R ¹ , R ² , and R ³ are each hydrogen and have 1 to 1 carbon atoms.
20, an alkyl group having 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group, an arylalkyl group, an acyloxy group having 1 to 20 carbon atoms, a cyclopentadienyl group, and a substituted cyclopentadiene group. X represents an enyl group or an indenyl group, and X ¹ represents a halogen.
a, b, and c each represent an integer of 0 to 4, and d and e each represent an integer of 0 to 3. ] It is described that it is at least one compound selected from the group consisting of a titanium compound and a titanium chelate compound represented by.

Further, it is also described that it is a condensate obtained by modifying trimethylaluminum with water as a cocatalyst. Further, as R ¹ _a R ² _b R ³ _c , a cyclopentadienyl group, a substituted cyclopentadienyl group (specifically, a methylcyclopentadienyl group, a 1,2-dimethylcyclopentadienyl group, a pentamethylcyclo A pentadienyl group) or an indenyl group. It is also described that these R ¹ , R ² and R ³ may be the same or different. X ¹ is halogen,
That is, chlorine, bromine, iodine or fluorine is shown. Further, it is described that a, b, and c each represent an integer of 0 to 4, and d and e each represent an integer of 0 to 3.

For example, cyclopentadienyl titanium trichloride, biscyclopentadienyl titanium dichloride and the like are mentioned as examples of specific compounds. However, even if styrene is polymerized using these specifically listed titanium compounds as catalysts, according to those publications, the amount of syndiotactic polystyrene obtained per g of titanium in terms of catalyst is equivalent. It is at most 10 Kg-polymer / g-titanium, and a higher catalytic activity is required from an industrial viewpoint.

Further, in Japanese Patent Publication No. 1-501487,
In producing a polymer of vinyl aromatic monomers having a high degree of syndiotacticity, one or more aromatic monomers are treated under polymerization conditions with an effective catalytic amount of a methylaluminoxane corresponding to the formula: CpTiX _3. A method is proposed which comprises contacting the catalyst with the reaction product with a monocyclopentadienyl / titanium complex. In the above formula, Cp is a π-bonded cyclopentadienyl group, π
A substituted or polysubstituted cyclopentadienyl group or a π-bonded monovalent oligomer of cyclopentadiene, X
Each independently proposes to be halogen, OR or NR ₂ .

As a specific titanium catalyst compound, pentamethylcyclopentadienyl titanium triphenoxide,
Pentamethylcyclopentadienyl titanium trichloride and the like have been proposed, but the catalytic activity shown in these publications is at most 20 Kg-polymer / g-titanium, which is still insufficient. Further, the above-mentioned JP-A-62-187
The thermal stability when obtaining a molded article of the polymer obtained according to JP-A No. 708 and JP-A No. 1-501487 is insufficient, and a polymer having good thermal stability is required.

[0008]

DISCLOSURE OF THE INVENTION The present invention finds a catalyst showing higher catalytic activity for producing syndiotactic polystyrene, and further to obtain a polymer having high thermal stability of the obtained product. The challenge is to obtain it.

[0009]

In order to solve the above-mentioned problems, the inventors of the present invention have made earnest studies on a polymerization catalyst, and as a result, trimethylaluminum or organoaluminum containing trimethylaluminum as a main component, using a titanium compound as a catalyst. When a syndiotactic polystyrene or its derivative is produced by polymerization of styrene or a styrene derivative using a condensate of water and water as a co-catalyst, the titanium compound has one cyclopentadienyl group or a substituted cyclopentadienyl group. A compound represented by the general formula CpTiF ₃ (wherein Cp represents a cyclopentadienyl group or a substituted cyclopentadienyl group and F represents a fluorine atom) gives a syndiotactic polymer of styrene or a derivative thereof. It was found that the effect is extremely high, This has led to the.

That is, the present invention relates to the discovery of a compound having extremely high activity, although it has been known that a titanium compound is an effective compound for providing syndiotactic polystyrene. Cyclopentadienyl titanium trichloride and pentamethylcyclopentadienyl titanium trichloride as halogen-containing titanium compounds are well known as catalysts for providing syndiotactic polystyrene. In general, cyclopentadienyl titanium trifluoride and substituted cyclopentadienyl titanium trifluoride are much higher in activity than trichloride compounds of the same series, even though chlorine and fluorine are generally treated as halogens. Is unexpected, and the inventor does not know the reason.

The condensate used as a co-catalyst is generally produced by a condensation reaction of trimethylaluminum or an organoaluminum compound containing trimethylaluminum as a main component with water, and is generally methylaluminoxane (abbreviation MAO).
is called. Aluminum (Al) in this condensate
And the molar ratio of titanium (Ti) in the titanium compound of the catalyst is 10: 1 to 50000: 1, and more suitably 50: 1 to 1
0000: 1, more preferably 100: 1 to 1000:
1, particularly preferably 150: 1 to 500: 1. If the amount of aluminum is too large, the amount of catalyst residue will increase, which will adversely affect the polymer characteristics, and if it is small, the polymerization activity will decrease, such being undesirable.

The polymerization is carried out at 20 to 110 ° C., preferably 25
At a temperature of ~ 90 ° C for a time sufficient to produce the desired polymer. Typical reaction times are a few minutes to a few hours, preferably 1 to 10 hours. The optimum time is determined by the temperature used, the solvent and other reaction conditions. The polymerization is generally performed under bulk or slurry polymerization conditions. In particular, bulk polymerization is preferred.

The polymerization can be carried out below atmospheric pressure as well as above atmospheric pressure. It is also carried out at reduced pressure until the lowest boiling component of the polymerization mixture evaporates. However, it is preferred to use a pressure near atmospheric pressure. Suitable styrenic monomers that can be polymerized by the method of the present invention have the formula

[0014]

Embedded image Including those indicated by. In the above formula, R is each independently hydrogen, suitably 1-10, more suitably 1-6,
Most suitably, it represents an aliphatic, cycloaliphatic or aromatic hydrocarbon group having 1 to 4 carbon atoms, or a halogen atom. Suitable monomers include, for example, styrene, chlorostyrene, n-butylstyrene, t-butylstyrene and p-vinyltoluene, with styrene being particularly suitable.

The polymerization is usually carried out in bulk or in the presence of an inert diluent. Diluents include aliphatic, cycloaliphatic, aromatic and halogenated aromatic hydrocarbons, and mixtures thereof. Preferred diluents, C ₄ ~ ₂₀
Includes alkanes, especially branched alkanes, toluene and mixtures thereof. A preferred diluent for the polymerization is isooctane or blends thereof, such as Exxon (Exx).
on) from Isopar-E®. Suitable solvents are used to give a monomer concentration of 5 to 100% by weight. During polymerization, the polymer precipitates out of the reaction mixture as it is formed. The most preferred method is bulk polymerization.

The molar ratio of the monomer to be supplied to the polymerization system and the titanium catalyst is 1 × 10 ⁴ : 1 to 5 × 10 ⁶ : 1 and preferably 1 × 10 ⁵ : 1 to 2 × 10 ⁶ : 1. If the amount of titanium is too large, it adversely affects the polymer properties, and if it is too small, the polymerization activity is reduced, which is not preferable.

The styrene polymer thus obtained has a high syndiotactic structure. Here, the highly syndiotactic structure in the styrene-based polymer is a syndiotactic structure having a high stereochemical 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. It means that the groups have alternating steric structures and their tacticity is determined by nuclear magnetic resonance ( ¹³ C-NMR) with isotopic carbon.

Tacticity quantified by the ¹³ C-NMR method is represented by the abundance ratio of a plurality of continuous constitutional units, for example, two diads, three triads, and five pentads. However, the "styrene-based polymer having a high degree of syndiotactic structure" referred to in the present invention is usually 75% or more, preferably 85% or more in racemic diad, or 30% or more in racemic pentad. , Preferably polystyrene having a syndiotacticity of 50% or more, poly (alkylstyrene), poly (halogenated styrene),
It means poly (alkoxystyrene), poly (vinyl benzoate), a mixture thereof, or a copolymer containing these as a main component.

Examples of poly (alkyl styrene) include poly (methyl styrene), poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene), and the like, and poly (halogenated styrene) Examples include poly (chlorostyrene), poly (bromostyrene), poly (fluorostyrene), and the like. Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).
Of these, particularly preferable styrene polymers include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tertiarybutylstyrene), poly (p-chlorostyrene), poly (m-chlorostyrene), poly ( Further, a copolymer of styrene and p-methylstyrene can be mentioned.

The styrenic polymer produced by the method of the present invention generally has a weight average molecular weight of 10,000 to 3,
, 000,000, preferably 100,000 to 1,50
0000, number average molecular weight 5,000 to 1,500,0
00 is preferably 50,000 to 1,000,000 and has high syndiotacticity as described above, but after polymerization, if necessary, deashing is performed with a cleaning liquid containing hydrochloric acid or the like, and If washed, a high-purity styrene polymer having extremely high syndiotacticity can be obtained.

Further, the conversion rate of the monomer to the polymer is 5%.
It is preferably 10% or more, more preferably 20% or more. The content of titanium in the polymer obtained by the polymerization system is 10 ppm or less, preferably 5 p, based on the polymer.
pm or less, more preferably 3 ppm or less, particularly preferably 2 ppm or less. The styrenic polymer having this highly syndiotactic structure has a melting point of 160 to 3
The heat resistance at 10 ° C is remarkably superior to that of a conventional styrene polymer having an atactic structure.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the following examples. This does not limit the scope of the invention.

[0023]

【Example】

Example 1 A mixture of 5 × 10 ⁶ moles of a cyclopentadienyl titanium trifluoride solution in toluene (5 ml), 1 mole of a purified styrene solution, and Al having a mole number of 1.5 × 10 ⁻³ of methylaluminoxane was mixed, Polymerization was carried out in an ampoule at 40 ° C. for 8 hours in a nitrogen atmosphere. After the reaction was completed, the obtained polymer was pulverized, washed with methanol and dried. The yield of the polymer after drying was 88%, and the polymerization activity was 382k.
It was g / g-titanium. When the polymer was extracted with methyl ethyl ketone at the boiling point for 4 hours, the methyl ethyl ketone insoluble portion (MIP) was 99%. Also,
Racemic pentad by ¹³ C-NMR is 95%,
When the molecular weight was determined by gel permeation chromatography (GPC method) using o-dichlorobenzene as a solvent, the weight average molecular weight was 320,000.

With respect to the polymer obtained here, (2,6-di-t-butylmethylphenyl) pentaerythritol diphosphite (trade name: PEP-3) is used as an antioxidant.
6, Adeka Argus Chemical Co., Ltd.) and tetrakis [methylene (3,5-di-t-butyl-4-hydroxyphenyl) -propionate] methane (trade name: Irg
Anox1010 and Nippon Ciba Geigy Co., Ltd. were each blended so as to be 0.1% by weight (the same applies to Examples 2 to 8 and Comparative Examples 1 and 2 below). When this polymer composition was heated under a nitrogen atmosphere, it melted at 268 ° C. The melt was held at 300 ° C. for 10 minutes (see Examples 2 to 2 below).
No foaming was observed in the melt, and it was found that the melt was thermally stable.

Comparative Example 1 The same operation as in Example 1 was carried out except that the titanium catalyst of Example 1 was changed to cyclopentadienyl titanium trichloride. The yield of the obtained polymer was 14%, the polymerization activity was 61 kg / g-titanium, and the methyl ethyl ketone insoluble portion was 88%. The racemic pentad by ¹³ C-NMR was 92%, the weight average molecular weight was 180,
The melting point was found to be 000, the melting point was 263 ° C., and the melt showed vigorous foaming and was found to be thermally unstable.

Example 2 The same operation as in Example 1 was carried out except that the catalyst of Example 1 was changed to pentamethylcyclopentadienyl titanium trifluoride. The polymer yield was 92%, and the polymerization activity was 400 kg / g-titanium. The methyl ethyl ketone-insoluble portion was 99%, the racemic pentad by ¹³ C-NMR was 96% or more, and the weight average molecular weight was 1,500,000. The melting point was 272 ° C. and the melt was thermally stable.

Comparative Example 2 The same operation as in Example 2 was carried out, except that the catalyst of Example 2 was pentamethylcyclopentadienyl titanium trichloride. The polymer yield was 14% and the polymerization activity was 61.
It was kg / g-titanium. The methyl ethyl ketone insoluble portion was 96%, the racemic pentad by ¹³ C-NMR was 95%, and the weight average molecular weight was 420,00.
It was 0. The melting point was 269 ° C., and the melt was violently foamed and was thermally unstable.

Example 3 The same operation as in Example 2 was carried out except that the polymerization temperature in Example 2 was changed to 70 ° C. The polymer yield was 92%, and the polymerization activity was 400 kg / g-titanium. The methylethylketone-insoluble portion was 99%, the racemic pentad by ¹³ C-NMR was 96% or more, and the weight average molecular weight was 500,000. The melting point was 272 ° C. and the melt was thermally stable.

Example 4 Example 3 was repeated except that the titanium catalyst concentration in Example 3 was 2 × 10 ⁻⁶ and the number of Al moles was 6 × 10 ^−4.
The same operation as described above was performed. The polymer yield was 53%,
The polymerization activity was 575 kg / g-titanium. The methylethylketone-insoluble portion was 99%, the racemic pentad by ¹³ C-NMR was 96% or more, and the weight average molecular weight was 500,000. The melting point was 272 ° C. and the melt was thermally stable.

Example 5 The same operation as in Example 4 was carried out except that the polymerization temperature in Example 4 was changed to 90 ° C. The polymer yield was 62%, and the polymerization activity was 673 kg / g-titanium. The methyl ethyl ketone-insoluble portion was 99%, the racemic pentad by ¹³ C-NMR was 96% or more, and the weight average molecular weight was 320,000. The melting point was 272 ° C. and the melt was thermally stable.

Example 6 Example 4 was repeated except that the polymerization temperature in Example 4 was 100 ° C.
The same operation as described above was performed. The polymer yield was 42%,
The polymerization activity was 456 kg / g-titanium. Moreover, the methyl ethyl ketone insoluble portion was 99%, and ¹³ C-NMR
Was 96% or more, and the weight average molecular weight was 220,000. Melting point is 269 ° C,
The melt was thermally stable.

Example 7 Example 4 was ^repeated , ^except that the titanium catalyst concentration of Example 4 was 1 × 10 ⁻⁶ and the number of moles of Al was 3 × 10 ⁻⁴ of methylaluminoxane.
The same operation as described above was performed. Polymer yield is 31%,
The polymerization activity was 674 kg / g-titanium. The methylethylketone-insoluble portion was 99%, the racemic pentad by ¹³ C-NMR was 96% or more, and the weight average molecular weight was 500,000. The melting point was 272 ° C. and the melt was thermally stable.

Example 8 The same operation as in Example 7 was performed except that the titanium catalyst of Example 7 was changed to cyclopentadienyl titanium trifluoride. The polymer yield was 25%, and the polymerization activity was 542k.
It was g / g-titanium. The methyl ethyl ketone insoluble portion was 96%, the racemic pentad by ¹³ C-NMR was 93%, and the weight average molecular weight was 210,000. The melting point was 264 ° C. and the melt was thermally stable.

Example 9 The compositions of the polymers containing stabilizers of Examples 1 to 8 and Comparative Examples 1 and 2 were measured for thermal stability at 310 ° C. for 10 minutes under a nitrogen atmosphere, and the results shown in Table 1 were obtained. was gotten.

[0035]

[Table 1]

[0036]

According to the present invention, polystyrene having a syndiotactic structure can be obtained with high efficiency. The thermal stability of the obtained polymer is also high.

[Brief description of the drawings]

FIG. 1 is a flow chart showing a catalyst adjusting step in the present invention.

Claims (1)

[Claims] 1. Syndiotactic polystyrene by polymerization of styrene or a styrene derivative using a titanium compound as a catalyst and trimethylaluminum or a condensation product of trimethylaluminum or an organoaluminum containing trimethylaluminum as a main component (abbreviation: MAO) as a promoter. Alternatively, when producing a derivative thereof, the titanium compound has a general formula CpTiF ₃ having one cyclopentadienyl group or a substituted cyclopentadienyl group (where Cp is a cyclopentadienyl group or a substituted cyclopentadienyl group). Group, and F is a fluorine atom) is used. A process for producing syndiotactic polystyrene or a derivative thereof, comprising: