JPS6337139B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a novel polyzirconocarbosilane derived from a polycarbosilane and an organic zirconium compound. Polycarbosilane, which is a polymer whose main chain skeleton consists of -(Si-CH ₂ -) and two side chain groups are bonded to each silicon atom, is made into an inorganic carbide SiC by firing.
It is known that SiC fibers with good mechanical and thermal properties can be produced by converting polycarbosilane into fibers and firing them. , for example, JP-A-51-126300, JP-A-51-139929.
This was disclosed in the No. 1 publication, etc. The present inventors subsequently discovered that the main chain skeleton was mainly -(
An organic compound of polycarbosilane consisting of structural units of Si-CH ₂ -) and polytitanosiloxane having titanoxane bonding units -(Ti-O-) and siloxane bonding units -(Si-O-) in the main chain skeleton. We have learned that SiC-TiC molded bodies obtained by firing metal copolymers have even better mechanical properties than SiC molded bodies. In addition, the present inventors found that the main chain skeleton is mainly -(Si-
Polycarbosilane consisting of structural units of CH ₂ −) and −(
A SiC-TiC molded body obtained by molding and firing an organometallic polymer derived from a titanium alkoxide (Ti-O-) bond unit has better mechanical properties than a SiC molded body. I learned that it is a body. Therefore, the present inventors have diligently continued research on the organometallic (co)polymers, and as a result, we have developed polycarbosilane whose main chain skeleton mainly consists of -(Si-CH ₂ -) structural units and -(Zr -O-) A new polyzirconocarbosilane derived from an organic zirconium compound having a bonding unit and a method for producing the same have been discovered, and a molded article mainly containing SiC-ZrC obtained by firing this polyzirconocarbosilane The present invention was developed based on the discovery that the ferrofluoride exhibits excellent mechanical properties and oxidation resistance at high temperatures. According to the present invention, mainly the general formula (However, R in the formula is a hydrogen atom, a lower alkyl group,
or phenyl group) whose number average molecular weight has a main chain skeleton represented by
200 to 10,000 polycarbosilane and an organic zirconium compound represented by the general formula ZrX ₄ (X in the formula represents an alkoxy group, phenoxy group, or acetylacetoxy group having 1 to 20 carbon atoms) The polyzirconocarbosilane has a number average molecular weight of 700 to 100,000, and the polyzirconocarbosilane has a polycarbosilane block in which at least a portion of silicon atoms are bonded to zirconium atoms via oxygen atoms. is a crosslinked block copolymer crosslinked with zirconium atoms through oxygen atoms, and -(Si
Provided is a polyzirconocarbosilane characterized in that the ratio of the total number of structural units of -CH ₂ -) to the total number of structural units of -(Zr-O-) is in the range of 2:1 to 200:1. be done. Furthermore, according to the present invention, the polycarbosilane and the organic zirconium compound are combined with the total number of structural units of each -(Si- _CH2- ) to -(Zr-O-).
In addition to the quantitative ratio such that the ratio of the total number of structural units of the polycarbosilane is within the range of 2:1 to 200:1, at least one of the silicon atoms of the polycarbosilane is heated and reacted in an atmosphere inert to the reaction. Provided is a method for producing a novel polyzirconocarbosilane having a number average molecular weight of about 700 to 100,000, which is characterized in that the polyzirconocarbosilane is bonded to the zirconium atom of the organic zirconium compound through an oxygen atom. The present invention will be explained in more detail below. The polyzirconocarbosilane of the present invention includes monofunctional polymers, bifunctional polymers, trifunctional polymers, and tetrafunctional polymers as illustrated below. [Table] X O H
｜ ｜
〜〜〜〜Si-C〜〜〜〜
｜ ｜
R H
【table】 ~ ~
O H
~ ~
｜
~ ~
R-Si-O-Zr-O-Si-R
~ ｜ ~
~ ~
O H
~ ~
｜ ｜
〜〜〜〜Si-C〜〜〜〜
｜ ｜
R H
(However, R and X have the same meanings as above.) That is, in a monofunctional polymer, the organic zirconium compound is bonded to the polymer chain of polycarbosilane as a pendant side chain,
In trifunctional and tetrafunctional polymers, two or more polycarbosilanes are crosslinked by -(Zr-O-) bonds. Although polycarbosilane itself and organic zirconium compounds themselves are known, a polymer composed of polycarbosilane and an organic zirconium compound has not been known until now. That is, it can be confirmed by gel permeation chromatography (GPC) and infrared absorption spectrum (IR) that the novel polyzirconocarbosilane of the present invention is a polymer having a structure different from that of polycarbosilane. Can be done. 1st
The figure shows GPC of polycarbosilane obtained by the method described in Reference Example 1 described later, and Figure 2 shows Example 1 described later.
According to the method described in , the polycarbosilane and zirconium alkoxide were mixed in a ratio of 10:8 (weight ratio).
This is GPC of the novel polyzirconocarbosilane of the present invention obtained by reacting with (in each case, a solution of 0.006 mg of the polymer dissolved in 5 ml of tetrahydrofuran was used for measurement). When compared with FIG. 1 in FIG. 2, a new peak that is not seen in FIG. 1 appears near the elution volume of 10 ml on the horizontal axis. This means that the new polyzirconocarbosilane obtained by the method of the present invention is not just a mixture of polycarbosilane and zirconium alkoxide, but has a higher molecular weight than polycarbosilane because the two are bonded through reaction. [In GPC, the lower the value on the horizontal axis of the peak (elution amount), the higher the corresponding molecular weight]. Next, FIG. 3 shows the IR of polycarbosilane obtained by the method described in Reference Example 1 described later, and FIG. 4 shows the IR of polycarbosilane obtained by the method described in Example 1 described later. This is the IR of the novel polyzirconocarbosilane of the present invention obtained by reacting at a ratio of 10:8 (weight ratio). The absorptions at 1250 cm ^-1 and 2100 cm ^-1 in the IR shown in Figure 3 are Si− present in the polycarbosilane starting material, respectively.
This absorption corresponds to CH ₃ and Si-H. In ^the IR of _the new polyzirconocarbosilane shown in FIG.
Comparing Figures 3 and 4 in terms of the ratio of m ^-1
and is decreasing. This means that due to the reaction between polycarbosilane and zirconium alkoxide, some of the Si-H bonds in polycarbosilane disappear,
This shows that polycarbosilane reacts with zirconium alkoxide and that polycarbosilanes are crosslinked by -(Zr-O-). That is, the novel polyzirconocarbosilane of the present invention produced by the method of Example 1 has a structural unit -(Si-
A part of the hydrogen atoms bonded as side chain groups to the silicon atoms of CH ₂ −) are detached, and the silicon atoms are bonded to the zirconium atom and oxygen atom of the bonding unit −(Zr−O−) of the zirconium alkoxide. It is generated by combining. In order to produce the novel polyzirconocarbosilane of the present invention, the method of the present invention involves heating a polycarbosilane and the organic zirconium compound in an atmosphere inert to the reaction without a solvent or in an organic solvent. However, at least a part of the silicon atoms of the polycarbosilane are bonded to the zirconium atoms of the organic zirconium compound via oxygen atoms. Although the polycarbosilane may be melted and reacted without a solvent, it is usually more advantageous to use an organic solvent to conduct the reaction smoothly and to suppress the formation of by-products such as gel-like substances. . Preferred solvents include, for example, n-hexane, benzene,
Examples include toluene, xylene, and tetrahydrofuran. In addition, it is necessary to carry out the reaction in an inert atmosphere such as nitrogen, argon, hydrogen, etc. If the reaction is carried out in an oxidizing atmosphere such as air, the raw material polycarbosilane and This is not preferred because it causes oxidation of the organic zirconium compound. The reaction temperature can be varied over a wide range; for example, when an organic solvent is used, it may be heated to a temperature below the boiling point of the organic solvent;
When obtaining a polymer with a high number average molecular weight, it is preferable to conduct the reaction by subsequently heating the organic solvent to a temperature higher than the boiling point to distill off the organic solvent. The reaction temperature is generally preferably 500°C or lower. The reaction time is not particularly important, but is usually about 1 to 10 hours. It is generally preferable to carry out the reaction near normal pressure; carrying out the reaction in vacuum or under high reduced pressure is not preferable because low molecular weight components will distill out of the system and the yield will decrease. To carry out the method of the invention,
It is preferable to carry out the reaction while feeding an inert gas into the reaction system as a gas stream, because this maintains the pressure inside the reactor at approximately normal pressure and reduces the temperature rise and hydrocarbon gas released during the reaction. This is because it is possible to prevent a pressure increase caused by a gas such as methane, for example. In the method of the present invention, the polycarbosilane used as one of the starting materials for producing the new polyzirconocarbosilane has a number average molecular weight of
200-10000, mostly general formulas (However, R in the formula is a hydrogen atom, a lower alkyl group,
or a phenyl group). In addition to the side chain described above, a hydroxyl group may be bonded to the silicon atom of the terminal group of the polycarbosilane. The method for producing polycarbosilane itself is known, and the polycarbosilane used as a starting material in the present invention can be produced by such a known method. For example, a method of directly thermally polymerizing monosilane is described in G. Fritz; Angew. Chem., 79 , 657 (1967) and G. Fritz et al; Adv. Inorg. Chem. Radiochem.
7, 349 (1965). There is also a method of manufacturing polycarbosilane by first converting monosilane into polysilane and then polymerizing it.
Publication No. 126300, Japanese Patent Publication No. 52-74000, Japanese Patent Publication No.
It is disclosed in Japanese Patent Application Laid-open No. 52-112700 and Japanese Patent Application Laid-open No. 54-61299. The main chain skeleton of the polycarbosilane used in the present invention is substantially -(Si-CH ₂ -)
It is a linear, network, and cyclic polymer having structural units of . In the method of the present invention, the organic zirconium compound used as another starting material for producing the new polytitanocarbosilane has the general formula ZrX ₄ (where X is an alkoxy group having 1 to 20 carbon atoms). group, phenoxy group, or acetylacetoxy group), and can be produced by a commonly used synthetic method for obtaining the compound. In the method of the present invention, the above-mentioned polycarbosilane and organic zirconium compound are divided into two groups: the total number of -(Si-CH ₂ -) structural units of the polycarbosilane and the -(Zr-O-) structure of the organic zirconium compound. In addition to adjusting the quantity ratio such that the ratio of the total number of units falls within the range of 2:1 to 200:1, a polymer is produced by heating reaction. Through this reaction, one of the side chain groups R bonded to the silicon atom in a part of the structural unit [Formula] in the main chain skeleton of the polycarbosilane is removed, and the silicon atom is transferred to the zirconium of the organic zirconium compound. Atoms are bonded through oxygen atoms. The novel polyzirconocarbosilane produced by the method of the present invention is a polymer with a number average molecular weight of about 700 to 100,000, and is a thermoplastic substance that is usually melted by heating to 50 to 400 ° C. Also, n-hexane, benzene, torque converter, xylene,
Soluble in solvents such as tetrahydrofuran. By firing the novel polyzirconocarbosilane of the present invention in a vacuum, an inert gas atmosphere, or a non-oxidizing gas atmosphere, the new polyzirconocarbosilane has superior mechanical strength compared to conventional SiC molded products, and SiC-TiC It can be converted into a molded body mainly composed of SiC and ZrC, which has better oxidation resistance at high temperatures than a molded body. Applications of such molded bodies include, for example, continuous fibers, films, coatings, powders, and the like. The novel polyzirconocarbosilane of the present invention can also be used as a sintering binder or an impregnating agent. Reference Example 1 2.5 g of anhydrous xylene and 400 g of sodium were placed in the three-necked flask of 5, heated to the boiling point of xylene under a nitrogen gas stream, and 1 portion of dimethyldichlorosilane was added dropwise over 1 hour. After the dropwise addition was completed, the mixture was heated under reflux for 10 hours to form a precipitate. This precipitate was filtered and washed first with methanol and then with water to obtain 420 g of white powder polydimethylsilane. On the other hand, 759 g of diphenyldichlorosilane and 124 g of boric acid are heated at a temperature of 100 to 120°C in n-butyl ether under a nitrogen gas atmosphere, and the resulting white resinous material is further heated at 400°C in vacuum for 1 hour. This yielded 530 g of polyborodiphenylsiloxane. Next, 8.27 g of the above polyborodiphenylsiloxane was added to and mixed with 250 g of the above polydimethylsilane, and the mixture was heated to 350°C under a nitrogen stream in a quartz tube equipped with a reflux tube for 6 hours to polymerize. Polycarbosilane, which is one of the starting materials for the invention, was obtained. After cooling at room temperature, xylene was added to take out the solution, xylene was evaporated, and the mixture was concentrated at 320° C. for 1 hour under a nitrogen stream to obtain 140 g of solid. The number average molecular weight of this polymer was determined using the vapor pressure osmotic pressure method (VPO method).
It was measured at 995. of this substance
When the IR spectrum was measured, as shown in Figure 3, Si-CH ₃ absorption was observed at around 800 cm ^-1 and at 1250 cm ^-1 .
C-H absorption at 1400, 2900, 2950 cm ^-1 , 2100 cm ^-1
absorption of Si−H at around 1020 cm ^-1 and around 1355 cm ^-1
Absorption of CH ₂ -Si was observed, and the obtained polymer is a polycarbosilane whose constituent elements are [Formula], [Formula], [Formula], etc. Reference example 2 Weigh out 100g of tetramethylsilane and use a recyclable flow-through device under a nitrogen atmosphere.
The reaction was carried out at 770°C for 24 hours to obtain polycarbosilane, which is one of the starting materials of the present invention. After cooling at room temperature, normal hexane was added to take out as a solution, filtered to remove insoluble matter, normal hexane was evaporated, and concentrated under reduced pressure of 5 mmHg at 180°C for 1 hour to obtain 14 g of sticky substance. Ta. The number average molecular weight of this polymer was measured using the VPO method.
It was 450. When the IR spectrum of this substance was measured, similar to Reference Example 1, various absorption peaks based on polycarbosilane were observed. Reference example 3 250g of polydimethylsilane obtained in reference example 1
was placed in an autoclave under an argon atmosphere.
Polycarbosilane, which is one of the starting materials of the present invention, was obtained by heating and polymerizing at 470° C. under about 100 atmospheres for 14 hours. After cooling at room temperature, add normal hexane and take out as a solution, evaporate normal hexane,
The solid obtained by concentrating at 280° C. for 1 hour under a reduced pressure of 1 mmHg was treated with acetone to remove low molecular weight substances to obtain 60 g of a polymer having a number average molecular weight of 8750. When we measured the IR spectrum of this substance, we found that
Similar to Reference Example 1, absorption peaks based on polycarbosilane were observed. Example 1 40.0 g of polycarbosilane obtained in Reference Example 1 and 31.5 g of zirconium tetrabutoxide were weighed out, 400 ml of xylene was added to this mixture to make a mixed solution consisting of a homogeneous phase, and under a nitrogen gas atmosphere,
The reflux reaction was carried out at 130° C. with stirring for 1 hour.
After the reflux reaction was completed, the temperature was further raised to 230°C to distill out the xylene solvent, and then polymerization was carried out at 230°C for 1 hour to obtain an organometallic polymer (polyzirconocarbosilane) containing zirconium metal. . The number average molecular weight of this polymer was 1677 as measured by the VPO method. The results of the gel permeation chromatography of this substance shown in Figure 2 and the results of the gel permeation chromatography of the polycarbosilane of Reference Example 1 shown in Figure 1 (the results of the gel permeation chromatography of the polycarbosilane of Reference Example 1) As is clear from the comparison of the gel permeation chromatograph of the material obtained by treatment under the same conditions as above in the absence of tetrabutoxide (same as in Figure 1), the polymer obtained here is It is not a simple mixture of the above-mentioned polycarbosilane and zirconium tetrabutoxide, but a polymer in which the two substances react to have a high molecular weight. Also the fourth
The IR spectrum of this material shown in the figure and the third
As is clear from the comparison with the IR spectrum of polycarbosilane shown in the figure, in the polymer obtained here, some of the Si-H bonds in the polycarbosilane have disappeared, and the silicon atoms in this part have become zirconium. It is bonded to the zirconium atom of tetrabutoxide through an oxygen atom, so that some of the polycarbosilane has -O-Zr(OC ₄ H ₉ ) ₃ groups in its side chain,
Some of them are organometallic polymers in which polycarbosilane is crosslinked with -(Zr-O-) bonds. Based on the above IR data, the reaction rate and/or crosslinking rate at the Si-H bond moiety in this polymer is calculated to be 49.7
%. The total number of -(Si- _CH2- ) bonds in _the polycarbosilane moiety of this polymer vs. -O-Zr( _OC4H9 ) ₃
The ratio of the total number of -(Zr-O-) bonds is approximately 8:1
It is. The polymer obtained here was treated in a nitrogen atmosphere.
The mixture was heated to 1700°C for 8.5 hours and calcined at 1700°C for 1 hour to obtain a black solid. When X-ray powder diffraction measurements were performed on this substance, as shown in Figure 5,
(111) diffraction line of β-SiC at 2θ = 35.8°, (220) diffraction line of β-SiC at 2θ = 60.1° and β at 2θ = 72.1°.
-SiC (311) diffraction line, ZrC (111) diffraction line at 2θ = 33.7°, ZrC (200) diffraction line at 2θ = 39.1°, 2θ
(220) diffraction line of ZrC at =56.3° and 2θ =67.0°
A (311) diffraction line of ZrC was observed. In particular, each diffraction line of ZrC is shifted to a higher angle than the 2θ of each diffraction line observed in conventional ZrC.
Since the lattice constant is different from that of ZrC, the obtained substance is estimated to be a composite carbide mainly consisting of β-SiC, ZrC, a solid solution of β-SiC and ZrC, and ZrC _1-x (0<x<1). be done. Example 2 The polymer obtained in Reference Example 1 was heated at 330°C for 3 hours.
The number average molecular weight obtained by concentrating under a nitrogen stream is
Weigh out 40.0 g of polycarbosilane 2990 and 75.3 g of zirconium tetraisopropoxide, add 500 ml of benzene to this mixture to make a mixed solution consisting of a homogeneous phase, and heat the solution at 70°C under an argon gas atmosphere for 50 minutes.
The reflux reaction was carried out while stirring for hours. After the reflux reaction was completed, the mixture was further heated and the benzene was distilled off.
Polymerization was performed at 150℃ for 2 hours, and the number average molecular weight was 9760.
Polyzirconocarbosilane was obtained. The total number of -(Si- _CH2- ) bonds in the polycarbosilane moiety of _this polymer versus -O-Zr(C- _isoC3H7 ) ₃ and -(Zr-O
-) The ratio of the total number of bonds is approximately 3:1. Based on the IR data of this material, the Si in this polymer
The reaction rate and/or crosslinking rate at the -H bond moiety is calculated to be 87%. Example 3 40.0 g of polycarbosilane obtained in Reference Example 2 and 14.3 g of tetrakisacetylacetonatozirconium
60 ml of ethanol and 300 ml of xylene were added to this mixture to obtain a mixed solution consisting of a homogeneous phase, and a reflux reaction was carried out with stirring at 60° C. for 8 hours under a nitrogen gas atmosphere. After the reflux reaction was completed, the mixture was further heated to distill off ethanol and xylene, and then polymerization was carried out at 180°C for 3 hours to obtain polyzirconocarbosilane having a number average molecular weight of 1380. −(Si−CH ₂ −) of the polycarbosilane part of this polymer
The ratio of the total number _{of bonds to the total number of -O-Zr(CH3COCHCOCH3)3 and -} (Zr-O-) bonds is approximately 23:1. When the reaction rate and/or crosslinking rate at the Si--H bond portion in this polymer is calculated based on the IR data of this substance, it is close to 100%. Example 4 40.0 g of polycarbosilane obtained in Reference Example 3 and 2.6 g of zirconium tetraphenoxide were weighed out, 200 ml of xylene was added to this mixture to form a mixed solution consisting of a homogeneous phase, and the mixture was heated under an argon gas atmosphere.
The reflux reaction was carried out at 130° C. with stirring for 2 hours.
After the reflux reaction was completed, the mixture was further heated to distill off xylene, and then polymerized at 300°C for 30 minutes to obtain polyzirconocarbosilane with a number average molecular weight of 19,300.
-(Si-) of the polycarbosilane part of this polymer
Total number of CH ₂ −) bonds vs. −O−Zr(OC ₆ H ₅ ) ₃ and −(
The ratio of the total number of Zr-O-) bonds is approximately 122:1.
The reaction rate and/or crosslinking rate at the Si--H bond moiety in this polymer is calculated to be approximately 7% based on IR data of this material.

[Brief explanation of the drawing]

Figure 1 shows gel permeation chromatography (GPC) of the polycarbosilane of Reference Example 1, and Figure 2 shows the gel permeation chromatography (GPC) of the polycarbosilane of Example 1.
GPC, FIG. 3 shows the infrared absorption spectrum (IR) of the polycarbosilane of Reference Example 1, and FIG. 4 shows the IR of the polyzirconocarbosilane of Example 1.
Further, FIG. 5 is an X-ray powder diffraction diagram of a composite carbide obtained by firing the polyzirconocarbosilane of the present invention of Example 1 at 1700° C. in a nitrogen atmosphere.

Claims (1)

[Claims] 1. Mainly general formula (However, R in the formula is a hydrogen atom, a lower alkyl group,
or phenyl group) whose number average molecular weight has a main chain skeleton represented by
200 to 10,000 polycarbosilane, and an organic zirconium compound represented by the general formula _Zr The total ratio of the total number of -(Si- _CH2- ) structural units of the polycarbosilane to the total number of -(Zr-O-) structural units of the organic zirconium compound is within the range of 2:1 to 200:1. In addition to the quantitative ratio, at least a part of the silicon atoms of the polycarbosilane are bonded to the zirconium atoms of the organic zirconium compound via oxygen atoms by a heating reaction in an atmosphere inert to the reaction. A method for producing a novel polyzirconocarbosilane having a number average molecular weight of approximately 700 to 100,000.