JPS6153376B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel organosilicon polymer mainly consisting of a carbosilane skeleton and a polysilane skeleton. A polymer that has a skeleton in which silicon atoms and carbon atoms are alternately bonded and has an organic side chain group on the silicon atom is called a polycarbosilane. It is used as a raw material for silicon carbide because it is converted into an inorganic substance whose main component is silicon carbide by firing.For example, it is used as silicon carbide fiber, sintering aid, impregnating agent, silicon carbide fine powder, etc. ing. Conventionally known polycarbosilanes include:
Fritz; Angew.Chem., 79 , which is synthesized by subjecting monosilane to a thermal decomposition condensation reaction at a high temperature of 600-800°C using a recyclable flow-through device.
p657 (1967), etc., and a patent application published in 1972, which is synthesized by subjecting organopolysilane to a thermal decomposition condensation reaction at 400-470°C under high pressure using a pressurized container such as an autoclave.
No. 50223, patent application No. 149468, patent application No. 149468, and patent application application No. 149468.
There are some disclosed in No. 21365, etc. Furthermore, the patent application filed by the present inventors in 1972-
The organopolysilane described in No. 127630,
By adding polyborosiloxane having a phenyl group to at least a part of the side chain of Si as a reaction accelerator and carrying out a thermal decomposition condensation reaction at 250-500°C under normal pressure, a polycarboxylic compound containing a part of siloxane bond is produced. Silane can be synthesized. These synthesis methods are industrially disadvantageous because they require a recyclable distribution device and high temperature, or require reactions under high pressure using a pressurized container. Further, when using a special reaction accelerator such as polyborosiloxane, the produced polymer contains siloxane bonds, so it is not suitable when it is desired to reduce the oxygen content in the fired product as much as possible. These conventional polycarbosilanes can be converted into silicon carbide by firing in a non-oxidizing atmosphere, making them extremely useful as raw materials for heat-resistant inorganic materials. Therefore, molded bodies having various shapes can be obtained. However, in order to heat and bake these molded bodies while retaining their shape, the molded polycarbosilane must be made infusible by curing as a pretreatment.
The best way to make it infusible is to heat it in air, but this requires either gradual heating to near the softening point of the polycarbosilane, or heating at low temperatures for a very long time. . However, conventional polycarbosilanes have drawbacks such as the molded body melting during heating to make it infusible, or the fact that infusibility cannot be sufficiently achieved to the inside of the molded body. This was extremely difficult. The present inventors have conducted extensive research to overcome the above-mentioned drawbacks of conventional methods. Therefore, we have invented a new method for producing an organosilicon polymer mainly consisting of a carbosilane skeleton and a polysilane skeleton, which does not require the use of special reaction accelerators and does not contain siloxane bonds. Furthermore, the present inventors found that the organosilicon polymer mainly composed of a carbosilane skeleton and a polysilane skeleton obtained by the above method is more easily rendered infusible than polycarbosilane obtained by a conventional method because it has a polysilane skeleton. It has been discovered that this is a novel organosilicon polymer with excellent performance in that it has a high firing residue rate in a non-oxidizing atmosphere. According to the invention, 0.5 to 10% by weight of one or more types of anhydrous metal halide is added to and mixed with polysilane having the following structure, and the mixture is heated to react in an atmosphere inert to the reaction. A method for producing an organosilicon polymer having a carbosilane skeleton and a polysilane skeleton is provided. The organosilicon polymer of the present invention obtained by the above method is estimated to be mainly composed of the following structural units (A), (B), (C), (D), (E) and (F). ,

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] (R represents CH ₃ or H) The structural unit forms a chain, branched, or cyclic structure, and further has a structure in the main chain skeleton.

It is an organosilicon polymer having a polysilane skeleton of the formula: (2≦n≦10). The organosilicon polymer of the present invention has absorption in the far infrared region of 450-300 cm ^-1 , has an absorption end in the ultraviolet absorption spectrum of 340-370 nm, and has a number average molecular weight of 400-5000. The present invention will be explained in more detail below. One of the starting materials used in the method of the invention is It is a polysilane having a structure of or _CH3
It is preferable that Polysilanes in which part of the methyl group is ethyl group, phenyl group, or hydrogen can also be used, but this is not preferable because the yield of the product decreases, and polysilanes having part of hydrogen are unstable and easily ignite. . The polysilane used in the present invention is, for example, published by Takeo Saegusa, Yoshihiko Ito, and Makoto Kumada in "Synthesis Reactions Using Organometallic Compounds (Part 2)" published by Maruzen, and published by M.Kumada.
and K. Tamao, Advan.Organometal.Chem.
6 , 19 (1968), etc., chain polysilanes can be synthesized by the condensation reaction of methylhalogenosilane with sodium, potassium, sodium-potassium alloys, or alkali metals such as lithium. is synthesized using. Another starting material used in the process of the invention is an anhydrous metal halide, each of the groups (alkaline earth metals and zinc group), group (alkaline earth metals and zinc group), group (excluding carbon), group (iron group), and Elements belonging to subgroup b and one or a mixture of two or more halides of antimony and bismuth can be used. As the metal halide, any of fluorides, chlorides, bromides, and iodides can be used, but chlorides and bromides are preferred, with chlorides being particularly preferred. Moreover, anhydrous metal halides are preferable, and when hydrated salts are used,
This is not preferable because the reaction may not proceed or the resulting organosilicon polymer will contain oxygen in its skeleton. Metal halides that can be used include:
For example, BeCl ₂ , SrCl ₂ , NdCl ₃ , ThCl ₄ , TiCl ₄ ,
_ZrCl4 , _HfCl4 , _VCl3 , _VCl4 , _NbCl5 , _TaCl5 ,
_CrCl3 , _MnCl2 , _FeCl3 , _CoCl2 , _ZnCl2 , _AlCl3 ,
_GaCl3 , TlCl, _SiCl4 , _GeCl4 , _SnCl4 , _PbCl2 ,
There are SbCl ₅ , SbCl ₃ , BiCl ₃ , AlBr ₃ and GaBr ₃ . Among these, AlCl ₃ , GaCl ₃ , MnCl ₂ , ZrCl ₄ ,
TiCl ₄ , VCl ₃ , CrCl ₃ are particularly suitable for increasing the molecular weight of the product, but by using a mixture of one of these and other chlorides,
Furthermore, if necessary, the reaction can be carried out in the presence of a trace amount of hydrogen halide, and the molecular weight distribution of the resulting organosilicon polymer can be easily controlled. In the method of the present invention, the above-mentioned One or a mixture of two or more of the above-mentioned anhydrous metal halides is added to the polysilane having the structure
0.5 to 10% by weight is added and mixed, and the mixture is heated to react in an atmosphere inert to the reaction. One of the important advantages of the method of the present invention is that a can-shaped reaction vessel made of stainless steel, for example, can be heated in a heating furnace such as an ordinary electric furnace without requiring any special equipment as a device for heating and reacting the mixture. At that time, it is sufficient to be equipped with a reflux device that can cool and reflux low-boiling components generated during the reaction, and an inlet and an outlet for gas inert to the reaction. There is no need to use containers or recyclable flow-through equipment, and another advantage is that readily available anhydrous halogens do not require the use of very special reaction promoters such as polyborosiloxane. The point is that chemical metals can be used. In the method of the present invention, the reaction by heating is
It is necessary to carry out the reaction under an inert gas atmosphere. If the reaction is carried out in an oxidizing atmosphere such as air, the raw material polysilane will be oxidized, which is not preferable. Nitrogen and argon are particularly suitable as the gas inert to the reaction. In addition, it is generally preferable to carry out the reaction at normal pressure; it is not preferable to carry out the reaction in vacuum or under reduced pressure because the produced low molecular weight components will be distilled out of the system and the yield will drop significantly. In order to carry out the method of the present invention, it is preferable to carry out the reaction while feeding an inert gas into the reaction section as a gas stream. This is because pressure increase due to gases such as hydrogen and methane generated during the reaction can be prevented. The heating temperature in the method of the present invention is lower than that in conventional methods, usually 250°C or higher, preferably 280°C or higher.
400° C. is one of the advantages of the method of the invention. If the reaction temperature is below 250°C, the reaction will not proceed sufficiently, and if it is above 450°C, gelation of the produced organosilicon polymer will occur, which is not preferable. In addition, the reaction time in the method of the present invention is usually 3 hours or more, and although it varies depending on the type of metal halide used, generally even if the reaction is carried out for 20 hours or more, there is no substantial effect on the organosilicon polymer obtained. No improvement is seen. In the method of the present invention, the amount of anhydrous metal halide added is 0.5 to 10% by weight based on the polysilane. The reason for this is that below 0.5%, the proportion of the polysilane skeleton in the organosilicon polymer produced is extremely large compared to the carbosilane skeleton, making it insoluble in ordinary organic solvents and in a non-oxidizing atmosphere. This is not preferable because the firing residual rate becomes extremely small. On the other hand, adding 10% by weight or more may cause the product to gel, and using anhydrous halogenation, which does not gel even if adding 10% by weight or more, is actually a problem in producing the organosilicon polymer of the present invention. This is uneconomical, and in that case it is practical to use a mixture of two or more anhydrous halides. The preferred amount of non-halide added is in the range of 1.0 to 8.0% by weight. The organosilicon polymer obtained by the above reaction can be purified by dissolving it in a solvent, heating if necessary, and then evaporating the solvent. The average molecular weight can be increased by removing low molecular weight components by distillation at normal pressure or reduced pressure within a temperature range. Examples of such solvents include n-hexane, cyclohexane, benzene, toluene, xylene, and tetrahydrofuran. In addition to distillation, another method for increasing the average molecular weight is to selectively precipitate and separate high molecular weight components using a mixed solvent of the above-mentioned good solvent and a poor solvent such as acetone, methanol, or ethanol. A novel feature of the process of the present invention is that from a mixture of polysilane with the addition of small amounts of anhydrous metal halide,
The process mainly produces organosilicon polymers consisting of a carbosilane skeleton and a polysilane skeleton, and has the advantage of not requiring special reaction equipment or a special reaction accelerator, and that the heating temperature is relatively low. Conceivable. Below, we will discuss the mechanism of why the above advantages are brought about by adding a small amount of anhydrous metal halide to polysilane, but this is just one speculation. However, the present invention is not limited in any way by this consideration. Polysilane, one of the starting materials for the process of the present invention, typically has a molecular weight of about 180
When heated at temperatures above ℃, thermal decomposition begins to occur gradually.
Thermal decomposition becomes more active from 250℃, and at 280℃ or higher, most of the substances, such as monosilane, are decomposed due to thermal decomposition.

[Formula] Low molecular weight polysilane, , or a mixture of partially carbosilated low molecular weight polysilanes, and thermal decomposition is approximately 400
Finish at °C. These low molecular weight products are easily released outside the reaction system, and in order to carry out the polymerization reaction with good yield, conventionally, in order to prevent the low molecular weight products from scattering, a pressurized sealed container or a low molecular weight It is possible to use special equipment, such as a flow-through device, to recycle molecular weight components into a heated part to gradually polymerize them, or to form and capture intermediate products by combining these low molecular weight components with siloxane. Special reaction promoters such as polyborosiloxanes were required. However, when a mixture of polysilane and anhydrous metal halide is used as a starting material in accordance with the method of the present invention, the low molecular weight product is efficiently converted into an organosilicon polymer consisting of a carbosilane backbone and a polysilane backbone. The mechanism is that a metal halide, represented by anhydrous aluminum chloride, undergoes a wide range of Friedel-Crafts reactions, including alkylation, ketone synthesis, carboxylic acid synthesis, aldehyde synthesis, halogenation, isomerization, and polymerization. Although it cannot be simply estimated because it is used as a catalyst, the following inference can be made, for example. The polysilane used in the present invention gradually begins to thermally decompose at a temperature of about 180°C or higher, producing low molecular weight components, but these are mainly due to radical cleavage of Si-Si bonds, and the generated radicals are the methyl groups of the polysilane. Pull out a hydrogen atom from. The methyl group from which hydrogen has been extracted undergoes a radical transfer reaction.

[Formula] may form a carbosilane bond, but since many radicals are generated in the reaction system, recombination of radicals mainly occurs, resulting in stable monosilane, polysilane, and partially carbosilane polysilane. It becomes a low molecular weight product, but if a metal halide is present at this time, halogenation of the methyl groups of polysilane occurs.
The mechanism is unknown However, this is probably due to the presence of trace amounts of hydrogen halides. Polysilanes having halogenated methyl groups are easily bonded to carbosilane by intramolecular rearrangement in the presence of a catalytic amount of metal halide. The halogen atoms that have been produced and moved onto the silicon atoms are extracted by the hydrogen present in the reaction system and regenerated as hydrogen halide, repeating the halogenation of the methyl group. Thus, the polysilane used in the present invention is converted into a carbosilane-rich polymer that is resistant to thermal decomposition before being decomposed into stable low molecular weight products. However, the catalytic action of metal halides on polysilane also acts on the intramolecular transfer of linear polysilane to branched polysilane and the ring reduction reaction of cyclic polysilane, and these reactions generally involve the thermal reaction of the most highly branched polysilane. in order to proceed towards producing the most stable isomer in terms of
The organosilicon polymer synthesized by the method of the present invention is formed from a carbosilane skeleton and a polysilane skeleton. Next, the organosilicon polymer comprising a carbosilane skeleton and a polysilane skeleton of the present invention obtained by the above-mentioned production method will be explained. The IR absorption spectrum of the organosilicon polymer of the present invention shows, for example, as shown in Figure ¹ , ^Si-
CH ₃ , 1410, 2900, 2950cm ^-1 and C-H, 2100cm ^-1
shows absorption based on Si-H at 1030 and 1355 cm ^-1 due to Si-CH ₂ -Si. Further, FIG. 2 shows an absorption spectrum in the far infrared region of 600 to 250 cm ^-1 , which shows broad absorption ranging from 300 to 450 cm ^-1 . This absorption is Si−Si
For example, 400 cm ^-1 for (Me ₂ Si) ₅ due to bond-based absorption,
(Me ₂ Si) ₆ shows an absorption peak at 383 cm ^-1 and (Me ₂ Si) ₇ shows an absorption peak at 362 cm ^-1 , which is unique to cyclic polysilanes.Of course, the linear polysilane used in the present invention absorbs in the far infrared region. Not shown. Therefore, in the skeleton of the organosilicon polymer obtained in the present invention, for example, a 5-membered ring, a 6-membered ring, a 7-membered ring, etc.
It was found that it contained a polysilane moiety such as a membered ring. Further, FIG. 3 shows the ultraviolet absorption spectrum. In this spectrum, the absorption end is 340−
It occurs at 370 nm and has large absorption in the ultraviolet region. For comparison, the polysilane used in the present invention was heated in an autoclave at 470°C for 14 hours at a final pressure of 110°C.
The absorption spectrum of polycarbosilane with a number average molecular weight of 1800 synthesized at Kg/cm ² is shown by a broken line. Polysilane is as shown in the table below.

【table】

[Table] Although the absorption maximum is often shown in the ultraviolet region, the absorption spectrum shown in Figure 3 shows that the

[Formula] (2≦n≦10) indicates that a chain and/or cyclic polysilane moiety is included. Common organic solvents such as hexane, cyclohexane, benzene, xylene, toluene, and tetrahydrofuran can be used, and n is 10 or less. Polymers in which n is 10 or more are insoluble in the above-mentioned common organic solvents. Furthermore, from measurements of ¹ H NMR spectra and ¹³ C NMR spectra, if we use tetramethylsilane as a standard substance and show the absorption peaks using chemical shift values, ^{the 1} H NMR spectra are 4.
Si-H at ~5.5ppm, SiMe ₂ at -1~1.5ppm,
SiMe, Si−CH ₂ −,

It shows a mixed and broad absorption peak of [Formula], and - even in ¹³ C NMR.
It shows only a broad absorption peak in the range of 7 to 20 ppm, and SiMe ₂ , Si−CH ₂ −,

It is supported that [Formula] etc. are mixed. The elemental ratio according to chemical analysis is generally Si: 40-55,
C: 30-40, O: 0.1-3.5, H: 6.5-8.5% by weight
The amount of metal elements in the polymer due to metal halides is less than 0.1% by weight, usually 0.05% by weight.
It is as follows. The above IR spectrum, ultraviolet absorption spectrum,
From the results of the NMR spectrum and chemical analysis, the following conclusions can be drawn regarding the structure of the organosilicon polymer of the present invention. In other words, the elements constituting the organosilicon polymer from the crystal in the IR spectrum are

【formula】 【formula】

[Formula], and further from the far infrared absorption spectrum

【formula】

【formula】

Cyclic polysilane moieties such as [Formula], and other than the above cyclic polysilane moieties according to the ultraviolet absorption spectrum.

[Formula] (2≦n≦10), is a chain polysilane moiety, and furthermore, from the ¹ H NMR spectrum and ¹³ C NMR spectrum,

【formula】

【formula】 【formula】

It is concluded that [Formula]. Of course, for example, it is formed from a carbosilane skeleton and a polysilane skeleton.

【formula】

Components such as [Formula] may also be present. Therefore, the organosilicon polymer of the present invention has substantially the following constituent units (A), (B),
It is estimated that it consists of (C), (D), (E) and (F), (R represents CH ₃ or H) These structural units form chain, branched, and cyclic structures, and furthermore, in the main chain skeleton.

It has a polysilane skeleton of the formula (2≦n≦10), and for example, the following molecular structure can be estimated. The organosilicon polymer obtained by the method of the present invention is
The number average molecular weight measured by vapor pressure osmosis is 400
-5000. The organosilicon polymer composed of a carbosilane skeleton and a polysilane skeleton obtained by the method of the present invention has an excellent property that it can be easily subjected to infusibility treatment because it has a polysilane skeleton, compared to polycarbosilane produced by a conventional method. have. In other words, when the polysilane skeleton is heated at low temperatures, it easily reacts with oxygen to form siloxane bonds.
In addition, ultraviolet rays easily generate radicals, thereby forming crosslinks between molecules and making them infusible. (1) In the present invention, 100 g of polysilane
1.5g of anhydrous aluminum chloride was added to the water at 355℃.
Organosilicon polymer obtained by heating for 16.5 hours and (2) conventional polysilane were heated at 470℃ in an autoclave.
Polycarbosilane obtained by reacting at a final pressure of 110 Kg/cm ² for 14 hours, and 3.2% by weight of polyborodiphenylsiloxane were added to (3) polysilane and heated at 350°C.
This is clear from the table below, which compares the polycarbosilane containing a siloxane bond obtained by reacting for 6 hours.

[Table] As shown in the above table, the organosilicon polymer obtained by the method of the present invention has excellent properties such as a high firing residue rate and easy production of molded products of various shapes. . That is, the organosilicon polymer obtained by the method of the present invention has a shape ranging from a viscous liquid at room temperature to a thermoplastic solid that melts when heated to 300°C, and has a shape that ranges from a viscous liquid at room temperature to a thermoplastic solid that melts when heated to 300°C. Since it is soluble in solvents such as toluene, xylene, and tetrahydrofuran, it can be made into molded bodies of various shapes, which can be made infusible by
This is extremely advantageous because it can be heated and fired in a non-oxidizing atmosphere at 800° C. or higher to convert it into a molded body mainly made of Si 2 C while maintaining its shape.
Examples of such materials include continuous fibers, films, and coatings mainly made of silicon carbide. The present invention will be explained below with reference to Examples. Example 1 2.5 g of anhydrous xylene and 400 g of sodium were placed in the 5-necked flask and heated to the boiling point of xylene under a nitrogen gas stream, and 1 dimethyldichlorosilane was added dropwise over 45 minutes while stirring. After the dropwise addition was completed, the mixture was heated under reflux for 10 hours to form a precipitate. After filtering this precipitate and first washing it with methanol,
After washing with water and drying, wash with acetone and benzene to form a white powder.

380 g of polysilane having the formula (n≧10) was obtained. Add 1.00, 1.25, 1.50, or 1.60 of anhydrous aluminum halide, AlCl ₃ to 100 g of this polysilane.
In a quartz tube equipped with a reflux tube, heat under a nitrogen stream and react for 8 hours or 16.5 hours. After the reaction is complete, pass as a xylene solution, remove impurities, and heat to 320℃. Distillation was performed in a nitrogen atmosphere to remove xylene and low-boiling components and concentrate to obtain the organosilicon polymer of the present invention. The results are shown in the table below. The reaction temperature hereinafter refers to the final reaction temperature.

[Table] Example 2 1.96, 2.50, 3.00, or 5.00 g of anhydrous zirconium chloride, ZrCl ₄ , was added and mixed to 100 g of the polysilane synthesized in Example 1, and the mixture was prepared in the same manner as in Example 1.
The organic silicon polymer of the present invention was obtained by reacting for a period of time. The results are shown in the table below.

[Table] Example 3 100g of polysilane synthesized in Example 1
MnCl ₂ , CrCl ₃ , VCl ₃ , TiCl ₄ or GaCl ₃ were added and mixed and reacted for 16.5 hours in the same manner as in Example 1 to obtain an organosilicon polymer of the present invention. The results are shown in the table below.

[Table] Example 4 To 100g of polysilane synthesized in Example 1,
_CnCl2 , _PbCl2 , _BiCl3 , _ZnCl2 , _SiCl4 , TlCl,
TaCl ₅ , FeCl ₃ , SnCl ₄ , or SrCl ₂ was added and mixed and reacted for 16.5 hours in the same manner as in Example 1 to obtain an organosilicon polymer of the present invention. The results are shown in the table below.

[Table] Example 5 100g of polysilane synthesized in Example 1
3.00 g of CoCl ₂ , PbCl ₂ or SiCl ₄ and 1.00 g of AlCl ₃
In addition, the organic silicon polymer of the present invention was obtained by reacting for 8 hours in the same manner as in Example 1. The results are shown in the table below.

[Table] Comparison of these results with Example 1 shows that the use of such mixed halides is advantageous when the number average molecular weight of the resulting organosilicon polymer is continuously changed.

[Brief explanation of the drawing]

Figure 1 shows the IR absorption spectrum (KBr tablet method) of the organosilicon polymer synthesized by adding 1.50 g of AlCl ₃ in Example 1 of the present invention, and Figure 2 shows the far-field spectrum of the same organosilicon polymer as in Figure 1. Infrared absorption spectrum (KI tablet method), Figure 3 shows the same ultraviolet absorption spectrum of the organosilicon polymer as in Figure 1.

Claims (1)

[Claims] 1. 0.5 to 10% by weight of one or more types of anhydrous metal halide is added and mixed to a polysilane having the structure of [Formula] (n≧3), which is inert to the reaction. By heating ^and reacting the mixture in an atmosphere of It has absorption peaks at -1 to 1.5 ppm in the ¹ HNMR spectrum and -7 to 20 ppm in the ¹³ CNMR spectrum, has a number average molecular weight of 400 to 5000, and is mainly composed of a carbosilane skeleton and a polysilane skeleton, and the polysilane skeleton is [Formula] (2≦n≦10) A method for producing an organosilicon polymer.