JP3414468B2 - Method for producing polycarbosilane - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a new process for producing polycarbosilane, known as a ceramic precursor polymer.

[0002]

2. Description of the Related Art A method for producing polycarbosilane by ring-opening polymerization of silacycloalkanes in the presence of various catalysts is known. For example, ring-opening polymerization of disilacyclobutane is generally performed by using a platinum compound as a catalyst. Wienberg et al. (DR Weyenberg,
L. E. Nelson, J .; Org. Chem. , 19
65, 30 , 2618), Banford et al. (WRB)
amford, J.M. C. Lovie, J .; A. C. Wa
tt, J.M. Chem. Soc. C, 1966, 113
In 7), platinum chloride is said to be particularly effective as a catalyst. However, in these examples the monomer is 1, 1, 3, 3
Limited to tetramethyl-1,3-disilacyclobutane.

On the other hand, Kleiner (WA Krine
r, J. Polymer Sci. , Part A-
1, 1966, 4 , 444), Nametkin et al. (NS.
Nametkin, V .; M. Vdovin, A .; V. Z
elenoya, Dokl, Akad. Nauk SS
SR. , 1966, 170 , 1088) that platinum chloride is effective in the ring-opening reaction of a compound having a phenyl group as a substituent on silicon, but requires heating at 80 ° C. or higher and a low molecular weight cyclic compound. Since carbosilane and an oligomer are by-produced, the yield of the target polycarbosilane is low, and the molecular weight distribution of this polymer is wide.

With respect to these problems, US Pat. No. 3,445
495, platinum olefin complex can be used as a polymerization catalyst in ring-opening polymerization of disilacyclobutane, and polycarbosilane from telomer to polymer can be produced by using a compound having a silicon hydrogen bond as a molecular weight regulator. Is disclosed. Further, in US Pat. No. 4,631,179, as a platinum complex as a catalyst for ring-opening polymerization of disilacyclobutane, diene platinum dichloride exemplified by chloroplatinic acid or dichloro (1,5-cyclooctadiene) platinum (II) is preferable. To be done.

[0005]

However, from the industrial point of view, these conventional methods have problems in productivity and economy in terms of halogen incorporation, storage stability of the catalyst and the like.
The present inventors have arrived at the present invention as a result of detailed investigations on the technology disclosed to solve this problem and various investigations on olefins as ligands for platinum catalysts. An object of the present invention is to provide a method for producing polycarbosilane which gives a better yield under milder polymerization conditions than those conventional polymerization methods using platinum chloride and the like. Another object of the present invention is to provide a method for producing polycarbosilane having controlled molecular weight and molecular weight distribution.

[0006]

The present invention is to obtain polycarbosilane by ring-opening polymerization of silacycloalkanes whose ring skeleton is composed of silicon and carbon, using a platinum-alkenylsiloxane complex as a catalyst. Is the gist.

The silacycloalkanes in the present invention are those whose ring skeleton is composed of silicon and carbon.
Specific examples thereof include silacyclobutane, benzosilacyclobutane, and disilacyclobutane.
It is not limited to these.

Among the above silacycloalkanes, especially the following formula (I)

[0009]

[Chemical 1]

Disilacyclobutane represented by the formula (1) is preferable in view of ring-opening reactivity, usefulness of the obtained polycarbosilane and structural stability. In the formula, R ¹ and R ² are the same or different monovalent organic groups containing no alkenyl group or halogen atoms, and specifically, alkyl groups such as methyl group, ethyl group, propyl group and butyl group; phenyl group , Tolyl group,
Aryl groups such as xylyl group and naphthyl group; benzyl group,
An aralkyl group such as a phenethyl group; a monovalent organic group such as an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, or a halogen atom such as fluorine or chlorine. From the viewpoint of stability and usefulness of the polymer structure, R ¹ and R ² are preferably methyl groups or phenyl groups. The disilacyclobutane represented by the formula (I) used in the present invention can be prepared, for example, according to the method reported by Auner et al. (N. Auner, J. Grob.
e, J. Organometal. Chem. , 198
0, 188 , 151. ).

The platinum-alkenylsiloxane complex in the present invention is a complex having a siloxane compound having an alkenyl group as a ligand, with platinum metal as the center, and is used as a ring-opening polymerization catalyst. Platinum-alkenylsiloxane complexes are described by Hitchcock et al. (P. B. Hitch
cock, M .; F. Lappert, N .; J. W. Wa
rhurst, Angew. Chem. Int. Ed.
Engl. , 1991, 30 , 438). Tris (tetramethyldivinyldisiloxane) diplatinum (0) can be particularly preferably used as the platinum-alkenylsiloxane complex. The alkenylsiloxane that can be used in the present invention may be a monoolefin or a diolefin, but a siloxane having an alkenyl group having 12 or less carbon atoms bonded thereto is preferably used. Although the reason why the platinum alkenyl complex having the above compound as a ligand gives high activity is not clear, the intramolecular rotation of the Si—O bond exerts some effect on the olefin coordination and contributes to the catalytic activity. Imagine something.
In the production method of the present invention, the addition amount of the platinum-alkenylsiloxane complex is not particularly limited, as long as it is an amount sufficient to initiate ring-opening polymerization of disilacyclobutane, and specifically, the molar amount of disilacyclobutane. Number to the number of moles of platinum-alkenylsiloxane complex is 10: 1 to 10000:
A range of 1 is particularly preferable because a good polymerization rate can be obtained.

The platinum-containing compound of formula (I)
The ring-opening polymerization using an alkenylsiloxane complex as a catalyst is preferably carried out in the presence of an organosilicon compound having at least one silicon-bonded hydrogen atom in one molecule.

An organosilicon compound having at least one silicon-bonded hydrogen atom in the molecule, that is, Si
When the -H functional organosilicon compound is added to the system, the molecular weight distribution of the produced polymer is narrowed and the polymerization rate is accelerated.
Specific examples of the Si-H functional silicon compound include trimethylsilane, triethylsilane, trimethoxysilane,
Triethoxysilane, trichlorosilane, methyldiethylsilane, methyldiethoxysilane, methyldimethoxysilane, methyldiphenylsilane, methyldichlorosilane, dimethylphenylsilane, 1,1,3,3-tetramethyldisiloxane, 2,4,4 Examples thereof include, but are not limited to, 6,8-tetramethylcyclotetrasiloxane, and any polymer or oligomer having at least one silicon-bonded hydrogen atom in one molecule may be used. . The amount of the Si-H functional organosilicon compound added is arbitrary, but the ratio of the number of moles of disilacyclobutane of the monomer represented by the formula (I) to the gram equivalent number of silicon atom-bonded hydrogen atoms of the organosilicon compound is A range of 20: 1 to 1000: 1 is preferable because a polycarbosilane having a good polymerization rate and a narrow molecular weight distribution can be obtained.

The polymerization can be carried out in a suitable solvent or without solvent. The solvent is not limited as long as it dissolves the monomer, the catalyst and the produced polymer well and does not adversely affect the reaction. Examples of the solvent include the following. Aliphatic hydrocarbons such as pentane, hexane, heptane, octane; Aromatic hydrocarbons such as benzene, toluene, xylene; Ether solvents such as diethyl ether, dibutyl ether, diphenyl ether, dioxane, tetrahydrofuran; Ethyl acetate, butyl acetate, etc. Ester solvent; acetone, methyl ethyl ketone,
Ketone solvents such as methyl butyl ketone; carbon tetrachloride,
Examples thereof include halogenated solvents such as chloroform, trichloroethane, trichloroethylene and tetrachloroethylene. Further, in the production method of the present invention, two or more kinds of the above solvents may be used in combination. Further, the presence of water during the polymerization is not preferable, but the polymerization may be carried out in the air, in an inert atmosphere or under pressure, and the polymerization may be carried out in a vacuum system without any problem.

The method for producing polycarbosilane of the present invention is as follows:
The reaction rate is determined by the type and concentration of the monomer used; the type and concentration of the platinum-alkenylsiloxane complex as a catalyst; the type and concentration of the Si-H functional silicon compound; and the polymerization temperature. The polymerization conditions are appropriately selected depending on the molecular weight of the target polycarbosilane, the molecular weight distribution and the like within the above range, but the polymerization temperature is preferably a temperature at which the catalyst is stable, and tris (tetramethyldivinyldisiloxane) 120 ° C for diplatinum (0) complex
The following is preferable.

[0016]

EXAMPLES The present invention will be described below with reference to examples. In the examples, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are the values obtained by gel permeation chromatography (GPC) using standard polystyrene. ¹
H-NMR, ¹³ C-NMR, and ²⁹ Si-NMR are proton nuclear magnetic resonance analysis, carbon 13 nuclear magnetic resonance analysis, and silicon 29 nuclear magnetic resonance analysis, respectively. IR
What is meant is infrared absorption analysis. Me is a methyl group, Ph is a phenyl group, and Et is an ethyl group.

(Example 1) 1,3-dimethyl-1,3-
Diphenyl-1,3-disilacyclobutane (1 g, 3.
7 mmol) and tris (tetramethyldivinyldisiloxane) diplatinum (0) (3.7 × 10 ⁻³ mmol) were placed in a glass reaction tube, deaerated, and then sealed. When this was immersed in an oil bath at 80 ° C., the fluidity of the monomer was lost within 1 minute after heating, so the polymerization was regarded as the end point. The reaction mixture was dissolved in chloroform, methanol was added thereto, and reprecipitation was performed to obtain 0.60 g (yield 60%) of a colorless solid compound. When the obtained compound was analyzed by GPC,
It was Mw = 130,000 (Mw / Mn = 2.7). This compound was analyzed by various nuclear magnetic resonance ( ¹ H-NMR,
As a result of analysis by ¹³ C-NMR, ²⁹ Si-NMR) and IR, it was found to be a polycarbosilane represented by the following general formula.

(—SiPhMeCH ₂ —) _n , n = 970.

Comparative Example 1 The same reaction as in Example 1 was repeated except that tris (tetramethyldivinyldisiloxane) diplatinum (0) was used.
When chloroplatinic acid hexahydrate (3.7 × 10 ⁻³ mmol) was used instead of the above, a temperature of 80 ° C. was obtained to obtain a yield of 60%.
It took 2 hours.

(Example 2) The same reaction as in Example 1 was carried out at 25 ° C.
After 20 hours, 62% of polycarbosilane Mw = 370,000 (Mw / Mn = 4.9) was obtained.

Comparative Example 2 The same reaction as in Comparative Example 1 was conducted at 25 ° C.
However, the fluidity of the reaction mixture was maintained even after 1 week, and the polymerization reaction did not proceed.

(Example 3) 1,3-dimethyl-1,3-
Diphenyl-1,3-disilacyclobutane (1 g, 3.
7 mmol) and tris (tetramethyldivinyldisiloxane) diplatinum (0) (3.7 × 10 ⁻³ mmol) in toluene 1
It was dissolved in 0 ml and reacted at 25 ° C. under an argon atmosphere. After 4 days, methanol was added to the reaction mixture for reprecipitation to obtain 0.59 g (yield 59%) of colorless solid polycarbosilane. When the obtained compound was analyzed by GPC, Mw = 290,000 (Mw / Mn = 4.
It was 9).

Comparative Example 3 The same reaction as in Example 3 was repeated except that tris (tetramethyldivinyldisiloxane) diplatinum (0) was used.
When chloroplatinic acid hexahydrate (3.7 × 10 ⁻³ mmol) was used instead of the above, 120% was obtained to obtain a yield of 47%.
It was necessary to heat at 0 ° C for 4 days. When this reaction was carried out at 25 ° C., the polymerization reaction did not proceed even after 1 week.

(Example 4) 1,3-dimethyl-1,3-
Diphenyl-1,3-disilacyclobutane (1 g, 3.
7mmol), phenyldimethylsilane (10mg, 7.4x
10 ⁻² mmol) and tris (tetramethyldivinyldisiloxane) diplatinum (0) (3.7 × 10 ⁻³ mmol) were placed in a glass reaction tube, degassed, and then sealed. The reaction proceeded at 25 ° C., and the fluidity of the reaction mixture was lost after 2 hours, so the polymerization was regarded as the end point. The reaction mixture was dissolved in chloroform, methanol was added thereto, and reprecipitation was performed to obtain 0.80 g (yield 80%) of a colorless solid compound. Various nuclear magnetic resonance analyzes ( ¹ H-NMR, ¹³ C-NMR,
²⁹ Si-NMR), IR analysis, and GPC analysis revealed that Mn = 10,000.
It was found to be a polycarbosilane represented by the following formula, in which (Mw / Mn = 1.3).

PhMe ₂ Si (CH ₂ SiMePh) _n
H, n = 75.

Comparative Example 4 The same reaction as in Example 4 was repeated except that tris (tetramethyldivinyldisiloxane) diplatinum (0) was used.
When dichloro (1,5-cyclooctadiene) platinum (II) (3.7 × 10 ⁻³ mmol) was used instead of the above, the reaction was slow at 25 ° C. and a yield of 80% was obtained. Four
It was necessary to heat at 0 ° C. for 3 days.

Example 5 The same reaction as in Example 4 was carried out with the amount of phenyldimethylsilane being 4 times (40 mg, 0.3 mmol), and Mn = 4,000 (Mw / Mn =
0.78 g (yield 78%) of polycarbosilane represented by the following formula, which is 1.3), was obtained.

PhMe ₂ Si (CH ₂ SiMePh) _n
H, n = 29.

Example 6 The same reaction as in Example 4 was replaced with phenyldimethylsilane and triethoxysilane (12 m
g, 7.3 × 10 ^-2 mmol),
0.65 g (yield 65) of polycarbosilane represented by the following formula, in which n = 10,000 (Mw / Mn = 1.4).
%) Obtained.

(EtO) ₃ Si (CH ₂ SiMePh)
_n H, _n = 75.

(Example 7) In Example 1, the raw material monomer (1,3-dimethyl-1,3-diphenyl-1,3-) was used.
(Disilacyclobutane) was replaced with 1,1,3,3-tetramethyl-1,3-disilacyclobutane. 1,
1,3,3-Tetramethyl-1,3-disilacyclobutane (1 g, 6.9 mmol) and tris (tetramethyldivinyldisiloxane) diplatinum (0) (3.7 × 10 ⁻³ mmol) were ice-cooled. Upon addition below, an exothermic reaction occurred immediately resulting in loss of monomer fluidity within 1 minute. The reaction mixture was dissolved in chloroform, and methanol was added to this to reprecipitate to obtain 0.80 g of a colorless rubber compound (yield 80
%)Obtained. When the obtained compound was analyzed by GPC, it was Mw = 760,000 (Mw / Mn = 5.4). This compound was analyzed by various nuclear magnetic resonance analysis ( ¹ H-NM
As a result of analysis by R, ¹³ C-NMR, ²⁹ Si-NMR) and IR, it was found to be polycarbosilane represented by the following general formula.

(—SiMe ₂ CH ₂ —) _n , n = 10500.

[0033]

As described above, according to the production method of the present invention, the ring-opening polymerization reaction can be promoted at a lower temperature and in a shorter time than the conventional method, so that the production time is shortened and the cost is reduced. Can be achieved. In the method of the present invention, polycarbosilane having a narrow molecular weight distribution can be obtained by using an organosilicon compound having at least one silicon atom-bonded hydrogen atom in one molecule.

Continuation of the front page (56) Reference JP-A-3-17131 (JP, A) JP-A-5-105765 (JP, A) JP-B-43-23640 (JP, B1) (58) Fields investigated (Int .Cl. ⁷ , DB name) C08G 77/00-77/62

Claims (2)

(57) [Claims] 1. Using a platinum-alkenylsiloxane complex as a catalyst, the following formula (I): A method for producing polycarbosilane, which comprises subjecting the disilacyclobutane represented by the formula (9) to ring-opening polymerization. However, in the formula (I), R ¹ and R ² are a monovalent organic group containing no alkenyl group or a halogen atom. 2. A compound represented by the following formula (I): using a platinum-alkenylsiloxane complex as a catalyst in the presence of an organosilicon compound having at least one silicon-bonded hydrogen atom in one molecule. A method for producing polycarbosilane, which comprises subjecting the disilacyclobutane represented by the formula (9) to ring-opening polymerization. However, in the formula (I), R ¹ and R ² are a monovalent organic group containing no alkenyl group or a halogen atom.