JPS6310169B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel organosilicon polymer mainly consisting of a carbosilane skeleton and a polysilane skeleton, and a method for producing the same. 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 patent application No. 50-50223, 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., Patent Application No. 149468 and Patent Application No. 21365, No. 51.
There are some disclosed by No. Furthermore, a polyborosiloxane having a phenyl group in at least a part of the side chain of Si is added as a reaction accelerator to the organopolysilane described in Japanese Patent Application No. 127630/1987, which the present inventors previously applied for. under normal pressure
Polycarbosilane partially containing siloxane bonds can be synthesized by a method of thermal decomposition condensation reaction at 250-500°C. 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. Also, when using special reaction accelerators such as polyborosiloxane,
Since the produced polymer contains siloxane bonds, it is not suitable when it is desired to reduce the amount of oxygen 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 present invention, 0.5 to 10% by weight of one or more types of anhydrous metal halide is added to and mixed with a polysilane having the structure [Formula], and the polysilane is mixed in an atmosphere inert to the reaction. Provided is a method for producing an organosilicon polymer having a carbosilane skeleton and a polysilane skeleton, the method comprising heating a mixture to cause a reaction. The organosilicon polymer of the present invention obtained by the above method mainly consists of the following structural units (A), (B), (C), (D), (E) and (F), (R represents CH ₃ or H) The structural unit forms a chain, branched, or cyclic structure, and further has a polysilane skeleton of the formula (2≦n≦10) in the main chain skeleton. It is an organosilicon polymer. The organosilicon polymer of the present invention is usually 450-
It has absorption in the far infrared region of 300 cm ^-1 , and the absorption end occurs in the ultraviolet absorption spectrum between 340 and 370 nm.
The number average molecular weight is 400-5000. The present invention will be explained in more detail below. One of the starting materials used in the method of the present invention is a polysilane having the structure [Formula], which may be either chain or cyclic, or may be a mixture of such structures. However, a linear polysilane with 10≦n is preferable, and the terminal group is preferably OH or CH ₃ .
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 mixtures of one of these and other chlorides can be used to further increase the molecular weight 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, 0.5 to 10% by weight of one or a mixture of two or more of the anhydrous metal halides is added and mixed to the polysilane having the structure [Formula],
The mixture is heated to react under 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 an anhydride halide that 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 that it does not require special reaction equipment or a special reaction accelerator, and the addition 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 metal halide to polysilane, but this is just one speculation. Therefore, 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 active from 250℃, and at 280℃ or higher, most of the material is converted into monosilane, for example, due to thermal decomposition.
It is converted to a low molecular weight polysilane, (2≦n≦10), or a mixture of partially carbosilated low molecular weight polysilanes, and the thermal decomposition ends at about 400°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, pressurized closed containers,
Alternatively, special equipment such as a flow-through device that recycles low-molecular-weight components to a heated part and gradually converts them into polymers, or captures intermediate products formed by bonding these low-molecular-weight components with siloxane. Special reaction accelerators such as polyborosiloxanes capable of However, when a mixture of polysilane and anhydrous metal halide is used as a starting material according to the method of the present invention, the low molecular weight product is efficiently converted into an organosilicon polymer consisting of a carbosilane skeleton and a polysilane skeleton. The mechanism is that a metal halide, represented by anhydrous aluminum chloride, undergoes the so-called Friedel-Crafts reactions in a broad sense, 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. For example, as shown in Figure ¹ , the IR absorption spectrum of the organosilicon polymer of the present invention shows ^Si-
CH ₃ , 1410, 2900, 2950cm ^-1 and CH, 2100cm ^-1
It shows absorption based on Si-H at 1030 and 1355 cm ^-1 and 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,
It is unique to cyclic polysilanes as it shows an absorption peak at 383 cm ^-1 for (Me ₂ Si) ₆ and 362 cm ^-1 for ( _{Me 2} Si) 7.
Of course, the linear polysilane used in the present invention does not exhibit absorption in the far infrared region. Therefore, in the skeleton of the organosilicon polymer obtained in the present invention, for example, a 5-membered ring, a 6-membered ring,
It was found that it contained a polysilane moiety such as a 7-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℃ for 14 hours at a final pressure of 110Kg/
The absorption spectrum of polycarbosilane with a number average molecular weight of 1800 synthesized in cm ² is shown by a broken line. As shown in the table below, polysilane often exhibits an absorption maximum in the ultraviolet region, but the absorption spectrum shown in Figure 3 shows that [Formula] (2≦n≦ 10) contains a chain and/or cyclic polysilane moiety. Furthermore, from the measurement of ¹ H NMR spectrum and ¹³ C NMR spectrum, if we use tetramethylsilane as a standard substance and show the absorption peak using chemical shift values, Si-H, -1 to 1.5 ppm in ¹ H NMR spectrum is 4 to 5.5 ppm. SiMe ₂ in ppm,
It shows a mixed broad absorption peak of SiMe, Si-CH ₂ -, and [Formula], and also - in ¹³ C NMR.
It shows only a broad absorption peak in the range of 7 to 20 ppm, supporting the presence of a mixture of bonds such as SiMe ₂ , Si--CH ₂ --, and [Formula]. 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 IR spectrum shows that the elements constituting the organosilicon polymer are [Formula], [Formula], [Formula], and the far infrared absorption spectrum shows that the cyclic polysilane moieties such as [Formula], [Formula], [Formula], etc. According to the ultraviolet absorption spectrum, in addition to the above-mentioned cyclic polysilane moiety, there is a chain polysilane moiety of [Formula] (2≦n≦10), and furthermore, from the ¹ H NMR spectrum and the ¹³ C NMR spectrum, [Formula] [Formula] [Formula] [ It is concluded that the formula is Of course, constituent elements formed from a carbosilane skeleton and a polysilane skeleton, such as [Formula] [Formula], may also exist. Therefore, the organosilicon polymer of the present invention has structural units substantially consisting of the following (A), (B), (C), (D), (E) and (F), (R represents CH ₃ or H) These structural units form chain, branched, and cyclic structures, and further have a polysilane skeleton of the formula (2≦n≦10) in the main chain skeleton. For example, the following molecular structure can be estimated. The organosilicon polymer of the present invention has a number average molecular weight of 400 to 5000 as measured by vapor pressure osmosis. The organosilicon polymer composed of a carbosilane skeleton and a polysilane skeleton of the present invention has an excellent property that it can be easily treated to make it infusible because it has a polysilane skeleton, compared to polycarbosilane produced by conventional methods. . That is, the polysilane skeleton easily reacts with oxygen to form siloxane bonds when heated at low temperatures, and also easily forms radicals when exposed to ultraviolet rays, thereby forming crosslinks between molecules and making it 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.
350 by adding 3.2% by weight of polyborodiphenylsiloxane to the polycarbosilane obtained by reacting for 14 hours at a final pressure of 110Kg/cm ² and (3) polysilane.
This is clear from the table below, which compares this with polycarbosilane containing a siloxane bond obtained by reacting at °C for 6 hours. [Table] As shown in the above table, the organosilicon polymer of the present invention has excellent properties in that it has a large firing residue rate and can be easily formed into molded bodies of various shapes. That is, the organosilicon polymer of the present invention is
It has a shape ranging from a viscous liquid at room temperature to a thermoplastic solid that melts when heated to 300°C, and is soluble in solvents such as n-hexane, cyclohexane, benzene, toluene, xylene, and tetrahydrofuran. Can be molded into various shapes,
This is extremely advantageous in that it can be made infusible and then heated and fired in a non-oxidizing atmosphere at 800° C. or higher to convert it into a molded body mainly made of SiC 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, the product was further washed with acetone and benzene to obtain 380 g of polysilane having the formula (n≧10) as a white powder. Add 1.00, 1.25, 1.50, or 1.60 g of anhydrous aluminum halide, AlCl ₃ to 100 g of this polysilane.
was added and mixed, heated under a nitrogen stream in a quartz tube equipped with a reflux tube, and reacted for 8 hours or 16.5 hours. After the reaction was completed, it was filtered as a xylene solution, and after removing impurities, it was heated to 320℃ with nitrogen. Distillation was carried out in an 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 organosilicon 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 Add MnCl ₂ to 100 g of polysilane synthesized in Example 1,
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,
_CoCl2 , _PbCl2 , _BiCl3 , _ZnCl2 , _SiCl4 , TlCl,
Add and mix TaCl ₅ , FeCl ₃ , SnCl ₄ , or SrCl ₂ ,
The reaction was carried out in the same manner as in Example 1 for 16.5 hours to obtain the organosilicon polymer of the present invention. The results are shown in the table below. [Table] [Table] Example 5 CoCl ₂ was added to 100 g of the polysilane synthesized in Example 1,
Add 3.00 g of PbCl ₂ or SiCl ₄ and 1.00 g of AlCl ₃ ,
The reaction was carried out in the same manner as in Example 1 for 8 hours to obtain an organosilicon polymer of the present invention. 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. Has absorption in the far infrared region of 450-300 cm ^-1 in the infrared absorption spectrum, has an absorption end in the ultraviolet absorption spectrum of 340-370 nm, and has a number average molecular weight of 400-5000. An organosilicon polymer, the organosilicon polymer has a main chain skeleton as shown below (A),
Mainly consists of structural units (B), (C), (D), (E) and (F). (R represents CH ₃ or H) The structural unit forms a chain, branched, or cyclic structure, and further has a polysilane skeleton of the formula (2≦n≦10) in the main chain skeleton. An organosilicon polymer characterized by: