EP2262849A1 - SILICON-BORON-CARBON-NITROGEN CERAMICS AND PRECURSOR COMPOUNDS, METHODS FOR THE SALT-FREE POLYMERIZATION OF RNHAL3-NSI - X - BRMHAL2-M& xA; - Google Patents

Abstract

The present invention relates to novel methods for the salt-free polymerization of boron silyl amines, which have the structural characteristic Si-N-B, and boron hydrocarbonss, which have the structural characteristic Si-X-B, wherein X can be a methylene group or a hydrocarbon chain CxHy or a cyclic hydrocarbon unit, by reaction with disilazanes R3Si-NR-SiR3.  

Description

Silicon boron-carbon-nitrogen ceramics and precursor compounds, salt-free polymerization process of RnHal _3. "Si-X-BR _m Hal ₂ . _m

description

The present invention relates to novel processes for the salt-free polymerization of boronylamines having the structural feature Si-NB lo and borosilylhydrocarbons having the structural feature Si-XB, where X may be a methylene group or a hydrocarbon chain C _x Hy or a cyclic hydrocarbon unit, by the Reaction with disilazanes R ₃ Si-NR-SiR ₃ . According to DE 41 07 108 and DE 100 45 428, the synthesis of polymeric precursors for Si / B / C / N ceramics is achieved by crosslinking the one-component precursors TADB (CI ₃ Si-NH-BCI ₂ ) or DMTA (CI ₃ Si). NMe-BCI ₂ ) with ammonia or primary amines in an inert solvent. At first all chlorine atoms are replaced with amino or alkylamino groups. Subsequent condensation reactions crosslink the products primarily obtained to form polymers. When the chlorine atoms are replaced by the amino or alkylamino groups, hydrogen chloride is liberated which, under the given conditions, forms ammonium chloride or amine hydrochloride with the nitrogen compound used in excess. These 5 hydrochlorides precipitate as solids from the reaction solution and must be time-consuming filtered off from this before further processing.

The object of the present invention is the solvent-free crosslinking of the one-component precursors with disilazanes R ₃ Si-NR-SiR ₃ (R =H, alkyl, aryl, alkenyl) without the formation of solid coproducts. By choosing the stoichiometry and the reaction conditions, in particular the parameters pressure, temperature and time, the rheological properties of the polymers with regard to their melt spinning behavior, their use as Optimize coating materials or their application in solid or fiber composites and set them specifically.

The object of the present invention is also a synthesis of the oligomers or polymers without isolating and / or working up the monomeric precursors or intermediates, but subjecting the unprocessed mixtures directly to crosslinking. For this purpose, a chlorosilane and an excess disilazane are first reacted and then the resulting mixture of chlorodisilazane and excess disilazane is subsequently reacted with a haloborane, preferably BCI ₃ .

The object of the present invention is furthermore the conversion of the oligomeric or polymeric compounds into ceramic materials. This can be carried out either in an inert atmosphere (noble gases or nitrogen) or in a reactive atmosphere, the thermolysis in a temperature range of 25 to 2300 ⁰ C, preferably up to 1800 "C can be performed.

The objects underlying the invention have been achieved by a process for the preparation of silicon-boron-carbon-nitrogen polymers comprising the reaction of disilazanes of the formula (I) R ₃ Si-NR-SiR ₃ , wherein each R is independently hydrogen or a Hydrocarbon radical having 1 to 20 C atoms represents with a borosilylamine of the formula (II)

wherein

Each independently denotes Cl, Br or I,

R ¹ , R ² , R ³ and R ^{4 are} each independently hydrogen, Hal or 9 002569

3 represents a hydrocarbon radical having 1 to 20 C atoms, or with a borosilylhydrocarbyl of the formula (III)

in which

Each independently denotes Cl, Br or I,

R ¹ , R ² and R ^{3 are} each independently H ₁ Hal or a hydrocarbon radical having 1 to 20 carbon atoms, and

Each X is independently a linear, unbranched, branched or cyclic i5 hydrocarbon radical having 1 to 20 carbon atoms, or with a chlorosilane of the formula (IV) R ¹ R ² SiHaI ₂ , wherein

Each independently represents Cl, Br or I, and

R ¹ and R ^{2 are} each independently H or a hydrocarbon radical having 1 to

Represents 20 carbon atoms and with a chloroborane of the formula (V) RBCI ₂ , where R is hydrogen, Hal or a hydrocarbon radical having 1 to 20 carbon atoms, is reacted.

In the reaction carried out according to the invention, the reaction proceeds without the formation of solid by-products, which must be laboriously separated off in the processes known in the art5. It is therefore in particular a salt-free reaction. Furthermore, the inventive method can be carried out without solvent. The ability to produce without solvent and without the formation of solid by-products polyborocarbosilazanes, allows a synthesis without monomeric precursors or intermediates must be isolated or worked up, for example, would have to be purified. Rather, the unreacted reaction mixtures can be directly subjected to crosslinking or calcination. Polyborocarbosilazanes, which are silicon-boron-carbon-nitrogen compounds, can be obtained by the process according to the invention. The term polyborocarbosilazane encompasses both oligo- and polyborocarbosilazanes according to the invention and in particular comprises compounds having a size of from 250 to 100,000, preferably from 1,000 to 10,000 Da or a chain length from 3 to 1,000, in particular from 10 to 500 and preferably from 20 to 100 ,

In the process according to the invention, a disilazane of the formula (I) R ₃ Si-NR-SΪR 3 is used, where R is, in each case, independently hydrogen or a hydrocarbon radical having 1 to 20 C atoms, in particular 1 to 10 C atoms. The hydrocarbon radical may be, for example, an alkyl, an alkenyl or aryl radical. The hydrocarbon radical can be unbranched or branched i5. Furthermore, it may be a linear or cyclic radical.

The radical R in the disilazane is preferably a C ₁ -C ₆ -alkyl radical, in particular methyl. Particular preference is given to using disilazane or hexamethyldisilazane or heptamethyldisilazane.

In one embodiment of the invention, the reaction is carried out with a borosilylamine of the formula (II)

wherein each Hal independently represents Cl, Br or I, preferably Cl, 0 R \ R ² , R ³ and R ^{4 are} each independently H, Hal or a hydrocarbon radical having 1 to 20 C atoms, in particular having 1 to 10 C atoms , The radicals R ¹ , R ² , R ³ and R ⁴ may represent, for example, an alkyl, an alkenyl or an aryl group. As far as she is one 69

- 5 -

Hydrocarbon group may be unbranched or branched, linear or cyclic. The radicals R ¹ , R ² , R ³ and R ⁴ are preferably a C ₁ -C ₆ -alkyl radical or a halogen, in particular Cl. Particular preference is given to boron silylamines which are trichlorosilylaminodichloroborane (TADB), CI ₃ Si-NH-BCI ₂ and dichloroborylmethyltrichlorosilylamine (DMTA) ₁ Cl ₃ Si-NMe-BCI ₂ .

In a further preferred embodiment, the reaction is carried out with a borosilylhydrocarbyl of the formula (III)

wherein

Each independently is Cl, Br or I _1, in particular Cl, R ¹ , R ² and R ^{3 are} each independently H ₁ Hal or a hydrocarbon radical having 1 to 20 C atoms, in particular 1 to 10 C atoms, and X is a hydrocarbon group with 1 to 20 carbon atoms.

As far as R ¹ , R ² and R ^{3 are} a hydrocarbon radical, this may be unbranched or branched, linear or cyclic and represent, for example, an alkyl, alkenyl or aryl group. X is a bridging unit and preferably represents a methylene group, a hydrocarbon chain C _x H _y , wherein x = 2 to 20, in particular 2 to 10, and y = 0 to 40, in particular 2 to 20 or a cyclic hydrocarbon moiety, for example a group C ₆ H _4. particularly preferably, X represents CH _2, CHCH _3, CH ₂ CH _2, CH = CH, C≡C, CHCH ₂ CH _3, CHCH = CH ₂ or C ₆ H ₄ represents.

In a further preferred embodiment, first a chlorosilane R ¹ R ² SiHaI is reacted with a disilazane R ₃ Si-NR-SiR ₃ and the resulting mixture of chlorodisilazane and excess silazane EP2009 / 002569

- 6 - subsequently reacted with a chloroborane RBCI ₂ , preferably with BCI ₃ . In the chlorosilazane, the radicals R ¹ and R ^{2 are} each independently hydrogen, Hal, in particular Cl or a Ci to C ₂ o-, in particular a Ci to Cio hydrocarbon radical, in particular an aryl, alkyl, alkenyl or alkynyl radical. In the disilazane, the radicals have the meanings given above. In the chloroborane R is H, Hal or a Ci to C ₂ o-, in particular a C ₁ to C ₁₀ hydrocarbon radical. For complete reaction, the product is preferably gradually heated to 80 to 250 ⁰ C, for example at vacuum or atmospheric pressure while distilling off the volatiles.

The invention relates in particular to reactions of compounds R _n Hal ₃ . nSi-NR-BR _m Hal _2- m or RnHal 3-nSi-X-BR _m Hal _2-m or mixtures thereof, with disilazanes R ₃ Si-NR-SiR ₃ or mixtures thereof, each Hal being independently Cl, Br or I each R independently represents a hydrocarbon radical having from 1 to 20 carbon atoms or hydrogen, X may be a methylene group or a hydrocarbon chain C _x Hy or a cyctic hydrocarbon moiety, n is from 0 to 2 and m is 0 or 1.

In the reaction of the invention, the disilazane of the formula (I) is preferably used at least in stoichiometric amount or in excess and in particular at least in stoichiometric amount or in excess with the Borsilylaminen of formula (II) or / and the Borsilylkohlenwasserstoffen of formula (III). Stoichiometric amount means half an equivalent of disilazane per shark atom, in particular per Cl atom.

According to the invention, it is possible to use in each case one or more compounds of the abovementioned formulas and, in particular, to use mixtures of disilazanes, mixtures of borosilylamines, mixtures of borosilylhydrocarbons, mixtures of chlorosilanes or mixtures of chloroboranes. But it is also possible, only one at a time T / EP2009 / 002569

- 7 - to use single compound of the above formulas.

It has surprisingly been found that various chemical, physical-chemical and material science properties of the polymers can be easily and specifically determined by those used in the reaction

Conditions such as temperature, time, pressure and the choice of substituents

R and X or the number of silicon or boron-bonded halogen atoms and the chosen stoichiometry influence. Furthermore, it was found that the choice of reaction conditions and the reactants also allows the composition and properties of the ceramics obtained from the polymers by thermolysis to be controlled in a targeted manner.

The inventive method is carried out in particular at a temperature of -70 ⁰ C to 200 ⁰ C, preferably from -10 ⁰ C to 150 ° C. By using higher temperatures in particular polymers are obtained, which are characterized by a higher crosslinking and therefore rather high viscosity and partly incurred in solid form. When using low temperatures, in particular temperatures of <50 ⁰ C, however, liquid to low viscosity oligomers or polymers are obtained.

The reaction is preferably carried out for a period of 30 minutes to 72 hours, in particular 2 to 8 hours. During the reaction is preferably carried out at atmospheric pressure, whereas the workup of the products takes place at atmospheric pressure or reduced pressure, preferably at 10 ^'3 to 1013 mbar.

The novel process gives novel oligo- or polyborocarbosilazanes, which are likewise the subject of the invention. The new oligo- or polyborocarbosilazanes differ from hitherto known compounds in their simple processing and the fact that the rheological properties which are important for further use can be adjusted in a targeted manner by the temperatures and pressures used in the work-up. Another object of the present invention is the conversion of the resulting oligomeric or polymeric compounds into ceramic materials. For this purpose, the oligo- or polycarbosilazanes are pyrolyzed at temperatures between -200 ⁰ C and 2000 ⁰ C. The pyrolysis takes place in particular in an ammonia or inert gas atmosphere. An inert gas atmosphere preferably consists of noble gases or / and nitrogen. The pyrolysis preferably takes place at temperatures between -100 ⁰ C and 1800 ⁰ C _1, more preferably between 25 ° C and 1700 ⁰ C instead. After the pyrolysis, a calcination step is preferably carried out, preferably at the temperature between 800 ^° C. and 2000 ^° C., more preferably between 900 ^° C. and 1800 ^° C., wherein the calcination step preferably also takes place in an ammonia or inert gas atmosphere.

The oligo- or polyborocarbosilazanes according to the invention are outstandingly suitable in particular for the preparation of polymers or ceramic powders, coatings, fibers, shaped bodies, fiber composite materials or films.

embodiments

example 1

31.4 9 (195 mmol) of hexamethyldisilazane, Me ₃ Si-NH-SiMe _3, are charged and 15.0 9 (65 mmol) trichlorosilylaminodichloroborane (TADB), CI ₃ Si-NH-BCI2 added dropwise at -10 ^C C under vigorous stirring. When the addition is complete, the mixture is first heated to room temperature and then to 50 ^° C. for 3 h. Formed during the reaction of Me ₃ SiCl removed by slowly applying a vacuum (about 200 mbar) before at this pressure, the temperature first for 3 h at 80 ⁰ C, then 2 h at 120 ⁰ C and 2 h at 150 ° C elevated. Finally, the pressure at 150 ⁰ C is lowered to 10 mbar. What remains is a colorless, hard polymer powder which decomposes above 200 ^0C. The thermolysis at 1400 ⁰ C (argon) provides an X-ray amorphous Si / C / B / N-ceramic in 57% yield.

Example 2

13.67 9 (55.8 mmol) dichloroboryl-methyl-trichlorosilyl-amine (DMTA), CI Si- _{3-NMe 2} BCI are introduced at 0 ⁰ C and under vigorous stirring to once lo with 25.2 g (156 mmol) of hexamethyldisilazane, Me ₃ Si -NH-SiMe ₃ , offset. The mixture is first heated to room temperature and then to 5O ⁰ C for 3 h. The Me ₃ SiCl formed in the reaction is removed by slowly applying a vacuum (about 200 mbar) before the temperature is first raised to 80 ^° C. for 3 h at this pressure. Finally, the pressure at i5 this temperature is lowered to 5 mbar. The polymer remains as a colorless, highly viscous gel which, after freeze-drying, can be isolated as a colorless powder.

Example 3

20

4 g (19 mmol) of dichloroboryl-methyl-trichlorosilyl-amine (DMTA), CI ₃ Si-NMe-BCI ₂ are initially charged at 0 ° C. and while stirring vigorously with 12.9 g (80 mmol) of hexamethyldisilazane, Me ₃ Si -NH-SiMe ₃ , offset. The mixture is first heated to room temperature and then to 5O ⁰ C 5 for 3 h. Formed during the reaction of Me ₃ SiCl removed by slowly raising the temperature to an initial 50 ⁰ C, then at 70 ⁰ C and finally to 100 ⁰ C. The temperature is further gradually increased to up to 160 ⁰ C, with excess and / or by Condensation liberated hexamethyldisilazane distilled off. What remains is a high-viscosity polymer, o from which fibers can be obtained by a melt-spinning process at 90 ^° C. Thermolysis at 1400 ^° C. in an argon atmosphere gives an amorphous Si / C / B / N ceramic in 41% yield. Example 4

35.1 g (235 mmol) of methyltrichlorosilane, CH ₃ SiCl ₃ at 0 ⁰ C and 126 g (780 mmol) of hexamethyldisilazane was added. When the addition is complete, the

5 mixture heated to 25 ⁰ C, stirred for one hour and then cooled to -70 0C. 27.6 g (235 mmol) of BCI ₃ are slowly condensed in, the reaction solution is heated to 25 ^C after completion of the addition and the mixture is stirred overnight. The volatiles are distilled off by gradually increasing the temperature to 50 ⁰ C, 90 ⁰ C ₁ 120 ⁰ C and 150 ⁰ C in each case three hours) lo. What remains is a high-viscosity polymer from which in a melt spinning process at 85 ⁰ C - can win 95 ⁰ C green fibers. Thermolysis at 1400 ^° C. in an argon atmosphere gives a Si / C / B / N ceramic in 51% yield.

i5 Example 5

29.0 g (165 mmol) heptamethyldisilazane, Me ₃ Si-NMe-SiMe _3, are charged and 15.0 g (55 mmol) Trichlorsilyldichlorborylethan (TSDE), CI ₃ Si- CHCH ₃ -BCI ₂ was added dropwise at 0 ⁰ C under vigorous stirring. After finished

20 addition, the mixture is heated to 50 ⁰ C within four hours. The Me ₃ SiCl formed in the reaction is removed by slowly applying a vacuum (about 200 mbar) before the temperature is first raised to 80 ^° C. at this pressure. Finally, the pressure is lowered to 10 ^{~ 1} mbar. What remains is a colorless, viscous polymer gel, which yields a X-ray amorphous Si / C / B / N ceramic in 61% yield on thermolysis (1400 ^° C. ₁ argon).

Claims

 claims 1. A process for preparing silicon-boron-carbon-nitrogen polymers. Comprehensively, the reaction of disilazanes of the formula (I) R ₃ Si-NR-SiR ₃ , where each R independently of one another denotes hydrogen or a hydrocarbon radical having 1 to 20 C Represents atoms with a borosilylamine of the formula (II) wherein Each independently represents Cl ₁ Br or I, R ¹ , R ² , R ³ and R ^{4 are} each independently of one another hydrogen, Hal or a hydrocarbon radical having 1 to 20 carbon atoms or with a borosilylhydrocarbon of the formula (III) wherein Each independently is Cl ₁ Br or I, R ¹ , R ² and R ^{3 are} each independently H ₁ Hal or one Represents hydrocarbon radical having 1 to 20 carbon atoms and X is independently a linear, unbranched, branched or cyclic hydrocarbon radical having 1 to 20 carbon atoms, or with a chlorosilane of the formula (IV) R ¹ R ² SiHaI ₂ 5 in which Each independently is Cl ₁ Br or I and R ¹ and R ^{2 are} each independently H or a hydrocarbon radical having 1 to 20 C atoms and are reacted with a chloroborane of the formula (V) 10 RBCI ₂ in which R is hydrogen, Hal or a hydrocarbon radical having 1 to 20 carbon atoms, i5 converts. 2. The method according to claim 1, characterized in that each time HaI stands for Cl. 20 3. The method of claim 1 or 2, wherein the polymers are prepared without isolation and / or workup of monomeric intermediates. 5 4. The method according to any one of the preceding claims, characterized in that the disilazane of the formula (I) is used in stoichiometric amount or in excess. 0 5. The method according to any one of the preceding claims, characterized in that mixtures of disilazanes and / or mixtures of Borsilylaminen and / or mixtures of Borsilylkohlenwasserstoffen and / or mixtures of chlorosilanes and / or chloroboranes. 6. The method according to any one of the preceding claims, characterized in that a heating to 80 to 250 ⁰ C is performed. 7. Polyborocarbosilazane obtainable by the process according to one of claims 1 to 6. 8. A process for producing a Siliziumcarbonitrit ceramic, characterized in that a Polyborocarbosilazan is pyrolyzed according to claim 7 at a temperature between -200 ⁰ C and 2000 ⁰ C. 9. The method of claim 8, further comprising calcining at a temperature between 800 ⁰ C and 2000 ⁰ C. 10. Use of a Polyborocarbosilazans according to claim 7 for the preparation of polymers and / or ceramic powders, coatings, fibers, moldings, fiber composite materials or films.