JPH049169B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to high molecular weight polyorgano(hydro) which has excellent properties especially as a raw material for ceramics.
The present invention relates to a method for producing silazane in high yield.

[Conventional technology]

Traditionally, polysilazane has been made by reacting organochlorosilanes such as methyldichlorosilane with dry ammonia in a non-reactive solvent. However, the polymer obtained by this method is
Since it is a cyclic body with a low degree of polymerization, it is easily hydrolyzed by moisture in the air, and also suffers from large evaporation loss during high-temperature firing, making it undesirable as a raw material for ceramics. Furthermore, this production method had the drawback of low yield. Therefore, using such a cyclic body with a low degree of polymerization as a raw material, in the presence of a clay solid catalyst,
A method has been proposed for producing high-molecular-weight polysilazane by heating to 100 to 300°C to open the ring and polymerize it (Japanese Patent Application Laid-Open No. 1983-93100), but this method produces an insoluble and hard polymer. However, it is not preferred as a ceramic raw material, polymer curing agent, or surface treatment agent.

On the other hand, after reacting organochlorosilanes with dry ammonia, ammonium chloride is separated and removed to obtain a cyclic silazane with a low degree of polymerization.
A method using catalysts such as KH and NaH has been proposed [P. Seyferth et al; Communications of the American Ceramics Society].
American Ceramic Society) C-132(6)1984].
This method yields a ladder-like polysilazane with a high molecular weight, but it requires a two-step production process starting from organochlorosilanes, during which the yield is at most 84%, and a highly flammable solvent is used. Disadvantages include the need to use highly flammable catalysts and desiccants, and the catalysts and catalyst deactivators used are expensive and cannot be reused.

[Problem that the invention seeks to solve]

Therefore, the present invention provides a high molecular weight polyorgano(hydro)silazane suitable for use as a raw material for ceramics, particularly as a raw material for efficiently producing silicon nitride/silicon carbide bodies, in high yield without using an expensive catalyst. The present invention provides a manufacturing method.

[Means for solving problems]

The present invention is based on the fact that organohalosilanes form a borrowing body (Lewis salt) with a Lewis base [HJCampbell et al.
Furgusonet al.), J.Chem.Soc.(A)1508−1514,
1966], as organohalosilanes.
This is based on the knowledge that when the above-mentioned complex using an organo(hydro)dihalosilane having one hydrogen atom in the molecule is used as a reaction raw material, a polyorganosilazane with a high molecular weight particularly suitable for ceramic raw materials can be obtained. .

That is, the present invention provides a method for producing polyorgano(hydro)silazane, which is characterized by reacting a matrix of organo(hydro)dihalosilane and a Lewis base with dry ammonia.

The organo(hydro)dihalosilane used in the present invention has the following general formula (): (In the formula, R is an alkyl group, an aryl group, or a group other than the above in which the atom directly bonded to Si is carbon, and X is a halogen.) Among these, R usually has 1 to 7 carbon atoms, preferably 1 to 5 carbon atoms,
More preferred are 1-2 alkyl groups, 2-7 alkenyl groups, 5-7 cycloalkyl groups, and aryl groups, and X is usually fluorine, chlorine, bromine, and iodine, preferably chlorine. Ru. As the aryl group, phenyl, tolyl, xylyl, medityl, cumenyl, benzyl, phenethyl, α-methylbenzyl, benzhydryl, trityl, styryl, cinnamyl, biphenyl, naphthyl, etc. can be used. Among these,
Particularly preferred are methyl(hydro)dichlorosilane, ethyl(hydro)dichlorosilane, vinyl(hydro)silane, allyl(hydro)silane, phenyl(hydro)dichlorosilane, benzyl(hydro)silane, and the like. In the present invention, it is particularly important to use a compound of the general formula () having one hydrogen atom in the molecule; Therefore, the purpose of the present invention cannot be achieved.

The Lewis base used in the present invention is one that does not undergo any reaction other than the reaction that forms a borrowed body (Lewis salt) with an organo(hydro)dihalosilane, and can further decompose the formed borrowed body with ammonia. For example, tertiary amines (trialkylamines such as trimethylamine, dimethylethylamine, diethylmethylamine, and triethylamine, pyridine, picoline, dimethylaniline, and derivatives thereof), phosphine, stibine, arsine, and derivatives thereof (such as trimethylphosphine, phine, dimethylethylphosphine, methyldiethylphosphine, triethylphosphine, trimethylarsine, trimethylstibine, trimethylamine, triethylamine, etc.). Further, bases having a low boiling point and less basicity than ammonia (eg, pyridine, picoline, trimethylphosphine, dimethylethylphosphine, methyldiethylphosphine, triethylphosphine) are preferable. Furthermore, pyridine or picoline is preferable from the viewpoint of ease of handling and economy. The amount of Lewis base to organo(hydro)dihalosilane is 0.5 or more in molar ratio,
It is preferably 1.0 or more, more preferably 1.5 or more.

In the present invention, a Lewis base is added to the above organo(hydro)dihalosilane to form a borrowing element (Lewis salt). At this time, the reaction solvent may be a Lewis base alone or a non-reactive solvent and a Lewis base. It is better to use a mixture of Non-reactive solvents include hydrocarbon solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons, halogenated hydrocarbons such as halogenated methane, halogenated ethane, and halogenated benzene, aliphatic ethers, and aliphatic hydrocarbons. Ethers such as cyclic ethers can be used.

Preferred solvents are methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride,
Halogenated hydrocarbons such as ethylidene chloride, trichloroethane, tetrachloroethane, ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-dioxyethane,
Ethers such as dioxane, dimethyldioxane, tetrahydrofuran, tetrahydropyran, pentane, hexane, isohexane, methylpentane, heptane, isoheptane, octane, isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, ethylbenzene Hydrocarbons such as Among these solvents, dichloromethane and pyridine are particularly preferred from the viewpoint of safety. The concentration of organo(hydro)dihalosilane in the solvent can be arbitrary, but is between 1 and 15
It is preferably within the range of weight % (hereinafter abbreviated as %). Further, as conditions for forming a borrow body, the temperature may be any range as long as the reaction system becomes liquid, but preferably room temperature and normal pressure are preferable. Since the reaction is extremely fast, the reaction time can be set arbitrarily.

Next, the borrowed body produced in this way is reacted with dry ammonia to perform ammonolysis.
have them do it. The ammonia used at this time may be either gas or liquid. Ammonia is preferably dried by, for example, passing it through solid sodium hydroxide and then passing it through metallic sodium. The amount of ammonia added is preferably 0.5 to 20 times, preferably 4 to 15 times, and more preferably 5 to 10 times the molar ratio of organo(hydro)dihalosilane. The reaction solvent, reaction temperature, reaction pressure, and time may be the same as those for forming the borrow body. Further, it is desirable that the amount of water in the reaction system is, for example, 500 ppm or less.
After the reaction is complete, polysilazane is separated using conventional means such as centrifugation. The obtained polysilazane has the general formula (): (In the formula, R has the same meaning as in formula (1).) It has a structural unit represented by the following and has a degree of polymerization of 4 to 1,700.

〔Effect of the invention〕

According to the manufacturing method of the present invention, ceramics with low heat loss and high high temperature strength can be obtained in high yields, and various other advantages are also obtained. That is, when the polysilane produced by the method of the present invention is used as a curing agent for polyester resins, epoxy resins, etc., the tensile strength and thermal stability can be improved. Furthermore, when used as a coating agent, it can improve abrasion resistance, waterproofing properties, and acid resistance.

Therefore, the polysilazane produced by the method of the present invention can be used as raw materials such as silicon carbide and nitrides, curing agents for various synthetic resins, coating agents, water repellents, stabilizers for silicone rubber, films, etc. It is used extensively.

Furthermore, the present invention simplifies the manufacturing process in a method for obtaining high molecular weight polyorgano(hydro)silazane. That is, in the past, in order to obtain a high molecular weight polysilazane, it was necessary to first produce a cyclic product with a low degree of polymerization and then polymerize it in another step, whereas in the method of the present invention, a single The entire reaction can be carried out in one reactor.

Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto.

〔Example〕

Example 1 A four-neck flask with an internal volume of 200 ml, a gas blowing tube,
Using a device equipped with a mechanical stirrer, a distiller condenser, and a dropping funnel, the inside of the reaction system was purged with nitrogen gas. Cool the device in an ice bath;
Add 6.0 methyldichlorosilane (CH ₃ SiHCl ₂ ) to this
g (52.2 mmol) and 70 ml of dry dichloromethane. Then pass through the dropping funnel the dry pyridine
16.6 g (210 mmol) was added dropwise to form a matrix and a colorless solution was obtained. Then, while stirring this solution, add 4.10 g of dry ammonia to it.
(240 mmol) was blown in with nitrogen gas to carry out the amyl decomposition. During the reaction, a small amount of fume was produced, but no problems such as gas flow path clogging or adhesion to the inner wall of the reactor occurred. The addition of ammonia turned the reaction solution into a white slurry. After the reaction was completed, the reaction mixture was centrifuged and filtered. The solvent was removed from the liquid under reduced pressure to obtain 2.80 g of polymethyl(hydro)silazane as a colorless viscous oil. The yield was 91% on the Si substrate. When this viscous oil was measured using the vapor pressure drop method, the average molecular weight was found to be
It was found that the average degree of polymerization was 1.77×10 ³ and 30.

This product was calcined using a thermogravimetric analyzer in a nitrogen stream at a temperature increase rate of 5°C/min and a maximum reaching rate of 1000°C. The thermogravimetric analysis curve is shown in FIG.
The weight of the black solid residue after firing was 44% of that before firing. Therefore, it can be seen that the polysilazane produced by the method of the present invention is highly economical as a method for producing ceramic raw materials.

Comparative Example 1 The same reaction as in Example 1 was carried out using 5.5 g (47.8 mmol) of methyldichlorosilane, 67 ml of dichloromethane, and 4.1 g (240 mmol) of dry ammonia without using dry pyridine, and the reaction product was
Obtained 1.995 g as a colorless liquid. The yield was 70.7% based on Si, but the average amount of this product was 266%.
The average degree of polymerization was 4.5.

This product was fired under the same conditions as in Example 1 using a thermogravimetric analyzer. The thermogravimetric analysis curve is shown in FIG. The black solid residue weight after firing is 14
% was low.

Example 2 Ethyldichlorosilane (C ₂ H ₅ SiHCl ₂ ) 3.00 g
(23.2 mmol), dry pyridine 7.43 g (93.9 mmol),
The same reaction as in Example 1 was carried out using 3.40 g (200 mmol) of dry ammonia and 100 ml of dry dichloromethane to obtain 1.61 g of polyethyl (hydro)silazane as a colorless viscous oil. Yield is 95% based on Si, average molecular weight 1170, average degree of polymerization 16
It was hot. Further, when calcined under the same conditions as in Example 1, a black solid was obtained with a yield of 40%.

Example 3 Phenyldichlorosilane (C ₆ H ₅ SiHCl ₂ ) 4.12
g (23.3 mmol), dry pyridine 7.43 g (93.9 m
When the same reaction as in Example 1 was carried out using 3.40 g (200 mmol) of dry ammonia and 100 ml of dry dichloromethane, 2.82 g of polyphenyl(hydro)silazane was obtained as a colorless, highly viscous oil. The yield was 100% based on Si, the average molecular weight was 683, and the average degree of polymerization was 5.6. Further, when calcined under the same conditions as in Example 1, a black solid was obtained with a yield of 44%.

[Brief explanation of drawings]

FIG. 1 shows the thermogravimetric analysis curve of polymethyl(hydro)silazane produced by the method of the present invention.
FIG. 2 shows a thermogravimetric analysis curve of polymethyl(hydro)silazane produced by a conventional method.

Claims (1)

[Claims] 1. Organo(hydro)dihalosilane and 1 carbon number
Production of polyorgano(hydro)silazane, characterized in that a complex with at least one Lewis base selected from trialkylamine or trialkylphosphine having ~3 alkyl groups, pyridine or picoline is reacted with dry ammonia. Method. 2. The manufacturing method according to claim 1, wherein the organo(hydro)dihalosilane is an alkyl(hydro)dichlorosilane or an aryl(hydro)dichlorosilane having 1 to 10 carbon atoms. 3. The manufacturing method according to claim 1, wherein the Lewis base is at least one base selected from pyridine or picoline. 4. The manufacturing method according to claim 1, wherein the amount of the Lewis base is about 0.5 times the mole or more of the organo(hydro)dihalosilane.