JP2651464B2 - Modified polysilazane, production method thereof and use thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a modified polysilazane, a method for producing the same, and a use thereof, and more particularly, to a modified polysilazane which can be used as a precursor of silicon nitride and a silicon nitride-containing ceramic, The present invention relates to a production method and a coating agent and a binder containing the modified polysilazane as an essential component.

(Prior art)

Since silicon nitride sintered body is excellent in high temperature strength, thermal shock resistance and oxidation resistance, it can greatly contribute to energy and resource saving as a high temperature structural material for gas turbines, diesel engines, etc., or cutting tools. It is important as one of the high performance materials that can be used.

Conventionally, as a method for producing silicon nitride, a metal silicon powder is heated directly at 1300 ° C. to 1500 ° C. in a stream of nitrogen or ammonia, and is directly nitrided by silicon. It is obtained by heating, reducing silica with urea, and reducing the silica with nitrogen to react with the generated silicon, a gas phase synthesis method in which silicon tetrachloride and ammonia are directly reacted at a high temperature, and ammonolysis of silicon tetrachloride. An imide thermal decomposition method of heating silicon diimide in a non-oxidizing atmosphere to obtain silicon nitride is employed.

However, in the case of the above method, the reaction time is long, the heating step is complicated, and the obtained silicon nitride is mainly β-type silicon nitride containing a large amount of impurities and a large amount of impurities. Not only is the purification of the raw materials difficult, but the reaction time is long, and the product obtained is a mixed system of α-type silicon nitride and β-type silicon nitride. Quality, and in the case of the method,
Although there is an advantage in that high-purity α-type silicon nitride can be produced with a high yield, silicon diimide [Si (NH) ₂ ] x, which is a silicon nitride precursor, is practically limited because it is insoluble in a solvent. There were drawbacks, such as the necessity.

Furthermore, recently, a method of synthesizing silicon nitride by heating polysilazane obtained by thermally decomposing organic polysilazane at 800 to 2000 ° C. has been proposed (Hajime Saito, Journal of the Textile Society of Japan Vol. 38)
No. 1, pages 65 to 72 (1982)), this method has a disadvantage that silicon carbide and free carbon are generated simultaneously with silicon nitride.

On the other hand, an inorganic polysilazane soluble in a solvent was synthesized by Stock (Ber. 54. (1921). P740) in 1921 and the like, and in 1983 Seyferth [Comm. Am. Ceram. Soc. 1
3/14, (83)] and the like prove that this is useful as a silicon nitride precursor. The present inventors have paid attention to such a viewpoint and have proposed a method of obtaining high-purity α-type silicon nitride by subjecting an inorganic polysilazane to a heat treatment (Japanese Patent Application Laid-Open No. 59-207812).

However, in the conventional method for producing an inorganic polysilazane, in each case, since highly volatile dichlorosilane is used as a raw material, polysilazane generated on a gas pipe or a reactor wall of a reactor is fixed and a gas flow path is formed. There is a risk of clogging. In order to prevent the above adverse effects, it is necessary to maintain the reaction temperature at a low temperature to prevent scattering of dichlorosilane.Dichlorosilane is highly toxic and flammable, so it is used in a low-temperature closed container. There are drawbacks such as complicated handling such as the necessity of handling. Further, when synthesized polysilazanes such Stock is at normal temperature only oligomers n = 7 to 8 having the structure of SiH ₂ NH _n is a viscous liquid, in the case of such Seyferth is Stock, etc. It is an oily liquid with a more complex structure and a proton ratio of Si-H / N-H of about 3.3, but solidifies when heated at about 200 ° C or left at room temperature for 3-5 days. However, any of the polysilazanes could not be said to have sufficient properties as a precursor for a silicon nitride sintered body shaped at room temperature.

Therefore, the development of a method capable of synthesizing an inorganic silazane useful as a precursor of silicon nitride having higher molecular weight and spinnability with higher yield and more easily has been desired.

On the other hand, as a coating agent for the surface of a metal material or an inorganic material, a silicon-based paint, a polytitanocarbosilane-based paint, and a poly (disilyl) silazane polymer (for example,
No. 61-38933).

However, although silicone-based paints provide films with excellent heat resistance even in a high-temperature atmosphere of 200 ° C or higher, pinholes are likely to occur, and when the film thickness is increased to prevent the occurrence of pinholes, Cracks, blisters, or peeling may occur in the coating during firing. Since such a phenomenon is particularly remarkable in a temperature range of 300 ° C. or higher, it is necessary to reduce the crosslink density of the silicone resin when using a silicone-based paint, and thus the surface hardness of the formed coating decreases. The difficulty arises.

In addition, polytitanocarbosilane-based paints are fired at low temperatures (40
(0 ° C. or lower), the surface hardness is not sufficient, and the raw material production process is complicated, and the production cost is high.

In addition, the method using a poly (disyl) silazane-based polymer requires a process of performing thermal decomposition in an inert atmosphere or vacuum at a high temperature of 750 ° C. or higher, which involves many difficulties in its workability. Similarly, there has been a report on a coating film of silicon nitride obtained from polysilazane, but cracks have occurred and a film having sufficient practical value has not been obtained (WSCobling et al, “Formation of Ceramic C
ompositions Utilizing Polymer Pyrolysis ", p271-28
5, Materials Science Research voll, Emergent Proces
s Methods For High-Technology Ceramics edited by
RFDabis et.al, Plenun Press NY).

〔Purpose〕

A first object of the present invention is to provide a novel modified polysilazane suitable as a silicon nitride precursor and a method for industrially producing the same, and a second object is to provide heat resistance, abrasion resistance, and the like. An object of the present invention is to provide a coating agent having excellent chemical resistance and capable of forming a coating having a high surface hardness.

〔Constitution〕

According to the present invention, as a first invention, the following general formula (A)
Having at least one type of cross-linking represented by (D)
Moreover, the atomic ratio of nitrogen and silicon (N / S
i) is at least 0.80 and the number average molecular weight is from 200 to 500,00
A modified polysilazane polymer of 0 is provided.

(In the formula, R ₁ and R _{2 each} represent an alkyl group, an alkenyl group, a cycloalkyl group, an alkylamino group, an aryl group, or an alkylsilyl group, and n is 1 or 2.) , (Wherein, R ₁ and R _{2 represent a} hydrogen atom, an alkyl group, an alkenyl group,
It has a skeleton represented by a cycloalkyl group, an alkylamino group, an aryl group, or an alkylsilyl group), and is characterized in that a polysilazane having a number average molecular weight of 100 to 50,000 and an amine are subjected to a dehydropolycondensation reaction under basic conditions. And a method for producing a modified polysilazane having a number average molecular weight of 200 to 500,000.

Further, as a third invention, a cross-linked NH _n (n = 1
Or 2) having a number average molecular weight in which the atomic ratio (N / Si) of nitrogen and silicon bonded to a silicon atom is at least 0.80.
A coating agent comprising 200 to 500,000 improved polysilazane as an essential component is provided.

Further, as a fourth invention, it has a cross-linking NH _n (n = 1 or 2), and has a number average molecular weight of 200, in which the atomic ratio (N / Si) of nitrogen and silicon bonded to a silicon atom is at least 0.80.
Binders comprising up to 500,000 improved polysilazanes are provided.

The raw polysilazane used as a starting raw material of the modified polysilazane of the present invention has a skeleton represented by the following general formula.

In the above formula, R ₁ and R ₂ represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an alkylamino group, an aryl group or an alkylsilyl group. In this case, examples of the alkyl group include methyl, ethyl, propyl, butyl, octyl, and decyl; examples of the alkenyl group include vinyl, allyl, butenyl, octenyl, and decenyl; and examples of the aryl group include phenyl and tolyl. , Xylyl, naphthyl and the like, and examples of the alkylsilyl group include methylsilyl, ethylsilyl, propylsilyl, butylsilyl, octylsilyl, decylsilyl and the like.

The raw polysilazane of the present invention has a number average molecular weight of 100 to 50,000 and is composed of cyclic polysilazane, chain polysilazane, or a mixture thereof. The starting polysilazane preferably used in the present invention is a linear polysilazane having a number average molecular weight of 300 to 2,000, preferably 600 to 1,400.

The polysilazane shown above can be synthesized by a conventionally known method as shown below.

The present inventor patent application (JP _{60-145903) · SiH 2 Cl 2 +} 2Py → SiH 2 Cl 2 + 2Py adduct · SiH 2 Cl 2 · 2Py adduct + 3NH 3 → SiH 2 NH n + 2NH 4 Cl + 2Py BJAylett (USP3,318,823) ・ SiH ₂ Cl ₂ + Me ₃ NH → H ₂ Si (NMe ₂ ) ₂ + Me ₂ NH ・ HCl ・ H ₂ Si (NMe ₂ ) ₂ + Me ₂ NH ₂ → H ₂ SiNMe _n + Me ₂ NH ₂ + H
_Two The present inventor patent application (JP _{61-89230) · MeSiHCl 2 + 2Py →} MeSiHCl 2 · 2Py adduct · MeSiHCl · 2Py adduct + 3NH 3 → MeSiHNH n + 2Py + 2NH 4 Cl in the present invention, the polysilazane basic conditions wherein the starting material A dehydrogenation polycondensation reaction (hereinafter simply referred to as a polycondensation reaction) with ammonia or hydrazine is performed below. In this case, the postponement condition means that a basic compound, for example, a tertiary amine, a secondary amine having a sterically hindered group, phosphine, or the like coexists in the reaction system.
Such basic conditions can be formed by adding a basic compound to the reaction solvent, or by using a basic solvent or a mixture of a basic solvent and a non-basic solvent as the reaction solvent. Can be. The amount of the basic compound added is at least 5 parts by weight, preferably 2 parts by weight or more based on 100 parts by weight of the reaction solvent. If the amount of the basic compound is less than this, the polycondensation reaction is not smoothly promoted.

Any basic solvent can be used as long as it does not decompose the starting material polysilazane.
Such include, for example, trimethylamine,
In addition to tertiary amines such as trialkylamines such as dimethylethylamine, diethylmethylamine and triethylamine, pyridine, picoline, dimethylaniline, pyrazine, pyrimidine, pyridazine and derivatives thereof, pyrrole, 3-pyrroline, pyrazole, 2- Pyrazoline,
And mixtures thereof. Examples of the non-basic solvent include, for example, hydrocarbon solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons, halogenated hydrocarbons such as halogenated methane, halogenated ethane, and halogenated benzene; Ethers such as aromatic ethers and alicyclic ethers can be used. Preferred solvents are methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, hydrogen chloride such as ethylidene chloride, trichloroethane, tetrachloroethane, ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-dioxyethane, dioxane. , Ethers such as dimethyldioxane, tetrahydrofuran, tetrahydropyran, pentane, hexane, isohexane, methylpentane, heptane, isoheptane, octane, isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, ethylbenzene, etc. And the like.

The polycondensation reaction of the present invention is preferably carried out in a solvent as described above. In this case, the concentration of the starting polysilazane in the solvent is 0.1 to 50% by weight, preferably 1 to 12% by weight. If the concentration of polysilazane is lower than this, the intermolecular polycondensation reaction does not sufficiently proceed, and if it is higher than this, the intermolecular polycondensation reaction proceeds too much to form a gel. The reaction temperature is −78 to 300 ° C., preferably −40 to 180 ° C. At a lower temperature, the polycondensation reaction does not sufficiently proceed, and at a higher temperature, the polycondensation reaction proceeds too much to form a gel. Generate. The amount of ammonia or hydrazine used as the polycondensation reagent is 1 mol of polysilazane (average mol).
Is in the range of 0.01 to 5.0, preferably 0.5 to 3.0, and if it is lower than that, the polycondensation reaction does not proceed sufficiently,
If it is higher than this, the polycondensation reaction proceeds too much to form a gel. As the reaction atmosphere, air can be used,
Preferably, a basic atmosphere composed of ammonia, hydrazine or other amines, an inert gas atmosphere such as dry nitrogen or dry argon, or a mixed atmosphere thereof is used. In the polycondensation reaction in the present invention, ammonia or hydrazine as a raw material, pressure is applied during the reaction by hydrogen by-product, but pressurization is not necessarily required,
Normal pressure can be adopted. The reaction time varies depending on various conditions such as the kind and concentration of the starting material polysilazane, the kind and concentration of the basic solvent, the amount of ammonia or hydrazine added, or the polycondensation reaction, but is generally in the range of 0.5 to 20 hours. Is enough.

The optimum conditions for the polycondensation reaction vary depending on the average molecular weight and molecular weight distribution of the starting polysilazane, the molecular structure of the modified polysilazane, and the choice of ammonia or hydrazine. A general consideration in setting conditions is that the lower the average molecular weight of the starting polysilazane, the more stringent conditions (temperature, reaction time) are required.

In the present invention, when a polycondensation reaction is performed using a basic solvent, the basic solvent solution containing the modified polysilazane obtained is adjusted in its solution composition so that the content of the basic solvent is 30% by weight in the total solvent. Or less, preferably 5% by weight or less. Since the basic solvent acts as a catalyst for an intermolecular polycondensation reaction of the modified polysilazane, if the ratio of the basic solvent to the total solvent becomes too large, a gel is generated during long-term storage at room temperature. The adjustment of the solution composition can be performed, for example, by evaporating the modified polysilazane solution containing the basic compound obtained in the polycondensation reaction step, evaporating and removing the basic compound contained therein, and then removing the non-basic (non-basic) Reactivity)
This can be done by adding a solvent. When the content of the basic compound in the solution is high or when a basic solvent is used as the reaction solvent, the solution composition adjustment step including the evaporation and removal of the basic compound and the addition of the non-basic solvent is repeatedly performed. As a result, a stable solution composition can be obtained. In the present invention, the non-basic solvent for forming a stable solution of the modified polysilazane includes aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, and aliphatic ethers as described above. And an alicyclic ether.

The polycondensation reaction between polysilazane and ammonia or hydrazine in the present invention is considered to include the following elementary reaction.

(1) In the above general formula (I), when both R ₁ and R ₂ are organic groups (2) In the general formula (I), when _one of R ₁ and R ₂ is a hydrogen atom and the other is an organic group, (i) When R ₁ is hydrogen (Ii) When R ₂ is hydrogen (3) When R ₁ and R ₂ are both hydrogen atoms in the general formula (I), The modified polysilazane of the present invention is a polymer produced by a polycondensation reaction between the raw material polysilazane and ammonia or hydrazine as described above, and is represented by the general formulas (A) to (D) in a polysilazane molecule. At least one type of new cross-linking has been introduced to increase the molecular weight. The modified polysalazane of the present invention is characterized by the following molecular structure with respect to the raw material polysilazane.

(1) The ratio of nitrogen atoms bonded to silicon atoms increases.
As described above, the modified polysilazane of the present invention newly contains at least one kind of cross-linking represented by the general formulas (A) to (D), and the ratio of nitrogen atoms based on this cross-linking increases. In the case of the raw material polysilazane, the ratio (N / Si) of the nitrogen atom bonded to the silicon atom to the silicon atom is, for example, 0.60 to 0.75 for perhydropolysilazane, 0.90 to 0.97 for methylhydrosilazane, and 0.90 to 0.97 for N-methylsilazane.
0.67 to 1.50, 0.55 to 0.70 for N- (triethylsilyl) allylsilazane and 1.1 to 2.0 for N- (dimethylamino) cyclohexylsilazane, and 0.85 to 0.96 for phenylpolysilazane. , The N / Si ratio is 0.80 or more and 0.
98 or more, 1.6 or more, 0.87 or more, 2.2 or more, and 0.98 or more, which are enhanced. The upper limit of the ratio of the nitrogen atom to the silicon atom to the silicon atom (N / Si) is defined within a range in which the modified polysilazane does not gel, in other words, within a range showing solvent solubility. Usually less than 2.5,
Preferably it is 2.0 or less.

(2) The number average molecular weight range is from 200 to 500,000. The modified polysilazane of the present invention has a number average molecular weight of 10 as described above.
Using 0 to 50,000 polysilazane as a raw material,
From being formed by crosslinking the polymer by H _n bonds, the molecular weight will, of course, to have been increased than the molecular weight of the raw material polysilazane.
Generally, the modified polysilazane for the purpose of the present invention is
It has a number average molecular weight of 200-500,000, preferably 1500-10000.

The modified polysilazane of the present invention has the above-mentioned characteristics in molecular structure and is distinguished from the raw material polysilazane. In addition, the modified polysilazane has many branched structures. is there. Because of this branched structure, the modified polysilazane of the present invention has a higher molecular weight than the raw polysilazane, but gives improved results in solvent solubility. The inorganic silazane proposed by Seyferth et al. Is an oily liquid having a proton ratio of Si-H / N-H of about 3.3, which solidifies when heated at about 200 ° C or left at room temperature for 3 to 5 days. It is. In contrast, the modified polysilazane of the present invention has a molecular weight of 200 to 500,000, newly contains NH _n (n = 1 or 2) as a crosslinking group, and has a ratio of nitrogen atoms to silicon atoms (N / Si) of 0.8. As described above, the number of SiH ₃ groups in one molecule is usually twice or more as large as that of the raw material polysilazane and has solvent resolubility. The reason that the modified polysilazane of the present invention has more branched structures than the raw material polysilazane is that, in the polycondensation reaction of the present invention, in addition to the polycondensation reaction, for example, the following reaction occurs. It is thought to be due to.

The branched structure of the modified polysilazane of the present invention is, for example,
(SiN ₂ ) / (Si obtained by ¹ HNMR spectrum measurement
H ₃ ) [(SiH ₂ ): Si-H resonance area at δ 4.8 × 1 /
2, (SiH ₃ ): Si-H resonance area at δ 4.4 × 1/3]
It can be evaluated by the ratio. In the case of the raw material polysilazane, the (SiH ₂ ) / (SiH ₃ ) ratio is determined by this method (Reference Example 1).
5.0-8.2, Seyferth (Reference Example 2) 8.5-13.0 and Stoferth
In the ck method (Reference Example 5), it is in the range of 14.0 to 19.0, and the number of SiH _{3 in} one molecule is _{3 to 10} , 0 to 1 and 0 to 1, respectively.
However, when these are subjected to the modification of the present invention, (Si
H ₂ / SiH ₃₎ ratio respectively, 2,5～4.8,4.5～7.0 and 5.5
The value is reduced to 10.0, and the number of SiH _{3 in} one molecule is doubled.

The modified polysilazane of the present invention has the molecular structural characteristics as described above, and is physically characterized by a cross-linked NH _n
While having (n = 1 or 2), it is often soluble in an organic solvent, and in particular, a solid polymer obtained by removing a solvent from a modified polysilazane solution has a great feature of having resolubility in a solvent. Show. In the case of the conventional polysilazane, the stability is poor, and when the solvent is removed from the solution, a resinous solid is formed, which is insoluble in the solvent, but the modified polysilazane of the present invention does not show such a tendency. . Therefore, in the case of the conventional polysilazane, handling as a solid polymer was impossible or extremely difficult, whereas the modified polysilazane of the present invention can be easily handled as a solid polymer.

In the present invention, in order to form a coating agent using the modified polysilazane, the modified polysilazane may be usually dissolved in a solvent. As the solvent, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbon hydrocarbon solvents,
Halogenated hydrocarbons such as halogenated methane, halogenated ethane and halogenated benzene, and ethers such as aliphatic ethers and alicyclic ethers can be used. Preferred solvents are methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, halogenated hydrocarbons such as ethylidene chloride, trichloroethane, and tetrachloroethane, ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-dioxyethane, and cyokitasan. , Dimethyldioxane, tetrahydrofuran,
Ethers such as tetrahydropyran; and hydrocarbons such as pentanehexane, isohexane, methylpentane, heptane, isoheptane, octane, isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, and ethylbenzene.

When these solvents are used, two or more solvents may be mixed to adjust the solubility of the modified polysilazane and the evaporation rate of the solvent.

The amount (proportion) of the solvent used is selected so as to improve workability by the coating method used. The amount of the solvent varies depending on the average molecular weight, molecular weight distribution and structure of the modified polysilazane. And preferably in the range of 10 to 50% by weight.

Further, an appropriate filler may be added as needed. Examples of the filler include fine powders of oxide-based inorganic substances such as silica, alumina, zirconia, and mica, and non-oxide-based inorganic substances such as silicon carbide and silicon nitride. Depending on the application, metal powder such as aluminum, zinc, and copper can be added. Further examples of fillers include silica silica, quartz, novacurite, diatomaceous earth, and other silica-based materials: synthetic amorphous silica: kaolinite, mica, talc, wollastonite, asbestos, calcium silicate, aluminum silicate Glass bodies such as glass powder, glass spheres, hollow glass spheres, glass flakes, foam glass spheres: boron nitride, boron carbide, aluminum nitride, aluminum carbide, silicon nitride, silicon carbide, titanium boride, nitride Non-oxide inorganic substances such as titanium and titanium carbide: calcium carbonate: metal oxides such as zinc oxide, alumina, magnesia, titanium oxide, beryllium oxide: barium sulfate, molybdenum disulfide, tungsten disulfide, carbon fluoride and other inorganic substances: Metal powders such as aluminum, bronze, lead, stainless steel, zinc, etc .: carb Black, coke, graphite, pyrolytic carbon, carbon and the like of the hollow carbon spheres and the like.

These fillers may be of various shapes such as needles (including whiskers), granules, and scales, or may be used alone or in combination of two or more. Further, it is desirable that the particle size of these fillers is smaller than the film thickness that can be applied at one time. The addition amount of the filler is in the range of 0.05 part by weight to 10 parts by weight based on 1 part by weight of polysilazane, and the particularly preferable addition amount is in the range of 0.2 part by weight to 3 parts by weight. Further, the surface of the filler may be surface-treated by coupling agent treatment, vapor deposition, plating or the like before use.

Further, the coating agent, if necessary, various pigments,
Leveling agent, defoamer, antistatic agent, ultraviolet absorber, PH
Adjusters, dispersants, surface modifiers, plasticizers, drying accelerators, flow inhibitors may be added.

The coating agent prepared in this way is uniformly solvent,
Decomposed and coated on a base of metal, ceramics, plastic, etc. As a coating means as a coating, a normal coating method, that is, dipping, roll coating,
Bar coating, brush coating, spray coating, flow coating and the like are used. If the substrate is sanded, degreased, and variously blasted before coating, the adhesion performance of the coating composition is improved. After coating by such a method and sufficiently drying, heating and baking are performed. By this calcination, the modified polysilazane is crosslinked, condensed and cured to form a tough coating.

The above sintering conditions differ depending on the molecular weight and structure of the modified polysilazane, but at a moderate heating rate of 0.5 to 10 ° C / min.
Bake at a temperature in the range of ~ 1000 ° C. The preferred firing temperature is
The range is from 200 ° C to 500 ° C. The firing atmosphere may be either air or an inert gas.Since a non-oxidizing atmosphere forms a Si-N bond, and an oxidizing or hydrolyzing atmosphere forms a Si-O bond film. The atmosphere can be appropriately selected according to the base.

Therefore, the coating agent of the present invention is suitable as a surface protective agent for metals such as iron, aluminum, copper, stainless steel, brass and the like and ceramics, and also as an insulating film for multi-part wiring for electronic components.

In order to use the modified polysilazane as a binder, the following method is usually employed.

Therefore, by adding various ceramic powders and modified polysilazane to such a solvent and mixing them, it is possible to easily and uniformly disperse them as a binder in the ceramic powders. Here, since the modified polysilazane also acts as a deflocculant (dispersant), the present slurry is a homogeneous slurry connected for granulation or slurry molding. Therefore, as a molding method, a press molding method such as a mold press method and a rubber press method, and a slurry molding method such as an extrusion method, a sheet method, and a carry-in method can be applied.

When the molded body obtained as described above is sintered, the modified polysilazane is thermally decomposed, hydrogen is volatilized, and highly active Si and N react with the ceramic particles to act as a sintering binder. Strongly bond between the particles. Here, since the bonding strength is so strong that the preceramic polymer having a high thermal decomposition yield is used and further the preceramic polymer which does not leave an excess of carbon which does not participate in the bonding is used, the organic group essentially has an organic group. Without having, after pyrolysis
The modified polysilazane having a high-purity Si ₃ N ₄ composition can be said to be a preceramic polymer suitable as a binder for sintering. The form of Si ₃ N ₄ is usually amorphous or 1
Since it fills the space between ceramic particles in the form of extremely small crystal particles of 000 mm or less, it also plays a role as a granulation amount inhibitor.

The above reaction starts at about 400 ° C. and is completed at about 1500 ° C. Therefore, in the case of inorganic sintered ceramics represented by non-oxides such as Si ₃ N ₄ and SiC, conventionally, high-temperature sintering of 1700 ° C. or more has been performed.
At about 00 ° C., a ceramic molded sintered body having excellent mechanical properties despite relatively low density can be obtained.

Further, the amount of the modified polysilazane to be added can be increased or decreased without limitation according to the characteristics of the target sintered body, for example, strength, density, workability, and the like. This is because, unlike the conventional preceramic polymer, by controlling the degree of polymerization, the degree of melting can be reduced, and the softening of the molded body can be prevented even when a large amount is added.

In order to mold ceramics using such a binder, as described above, ceramic powder and modified polysilazane are added to a solvent and mixed to form a slurry to form a slurry, or a solvent is formed from this slurry. What is necessary is just to evaporate and produce granulated powder, and press-mold.

As an example, in order to apply the pressing method, the solvent in the slurry may be evaporated by a spray dryer to form granulated powder. At this time, the modified polysilazane works as a molding binder for granulation and, at the same time, is uniformly mixed in the ceramic powder as a sintered body binder (sintering aid). By pressing the granulated powder thus obtained, a compact having a predetermined shape can be obtained. Further, according to the slurry molding method, it is possible to obtain a molded body in which a binder for molding directly and uniformly for sintering is uniformly mixed without passing through granulated powder.

In the present invention, the ceramic molded body (sintered body) is immersed in a solution in which the modified polysilazane is dissolved in a solvent, and the ceramic molded body in which the modified polysilazane is impregnated with the modified polysilazane is fired. This makes it possible to densify the ceramic molded body (sintered body).

Examples of the solvent include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbon solvents, halogenated hydrocarbons such as halogenated methane, halogenated ethane, and halogenated benzene, aliphatic ethers, alicyclic ethers. And the like. Preferred solvents are methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, halogenated hydrocarbons such as etideline chloride, trichloroethane, tetrachloroethane, ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-dioxyethane, dioxane , Dimethyldioxane, theolahydrofuran, ethers such as tetrahydropyran, pentane, hexane, isohexane, methylpentane, heptane, isoheptane, octane, isooctane, cyclopentane, methylcyclopentane,
Hydrocarbons such as cyclohexane, methylcyclohexane, benzene, toluene, xylene, and ethylbenzene.

The obtained ceramic molded body is fired to convert the modified polysilazane into ceramics, whereby a ceramic molded sintered body can be obtained. The firing condition is at least one selected from the group consisting of an inert gas, a reducing gas, and a hydrocarbon gas in a vacuum.
Heat sintering in an atmosphere consisting of seeds within a temperature range of 600 to 2300 ° C.

The sintered body thus obtained has an amorphous structure or a structure formed by extremely fine particles of 1000 ° or less, which are generated by the thermal decomposition of polysilazane between the used ceramic particles or whiskers.

Thus, according to the present invention, by selecting polysilazane as a preceramic polymer and selecting polysilazane having no organic group in the side chain, ceramic forming and sintering excellent in mechanical properties and chemical properties at low temperature firing. The body is obtained.

〔effect〕

The modified polysilazane of the present invention has the above-mentioned molecular structural and physical properties and is preferably used as a coating agent and a binder, but can be used in various other fields. The application and production characteristics of the modified polysilazane of the present invention are described below.

Modified polysilazane is soluble in organic solvents and can be converted to silicon nitride or silicon nitride-containing ceramics by firing. Therefore, high-performance ceramic molded products, that is, high-temperature mechanical strength, heat resistance, corrosion resistance, and oxidation resistance ,
Continuous fibers, films and coating films having excellent thermal shock resistance can be easily obtained. Further, since the ceramic yield is high, it can be used as a binder for sintering, an impregnating agent, and the like.

Since the modified polysilazane does not contain impurities such as a residual catalyst which promotes decomposition in the polymer, the stability is improved, the handling is facilitated, and the purity of the ceramics after high-temperature firing is improved. .

The modified polysilazane has an increased cross-linking structure and molecular weight as compared with the raw material polysilazane, and thus has an improved solidification property, and can be rapidly shaped at room temperature.

Since a catalyst such as a transition metal is not used, a step of separating the product from the catalyst is not required.

Since no catalyst remains in the modified polysilazane, stability is improved, and long-term storage is possible even after isolation except for the solvent.

Since no expensive and dangerous catalyst is used, it is low-cost and safe.

Due to the high molecular weight, the evaporation loss during high-temperature firing is small, so that the ceramic yield is improved.

Since no impurities are mixed, the purity of the ceramic after high-temperature firing is improved.

When spinning the modified polysilazane, continuous spinning becomes possible without adding a spinning aid.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to examples.

Reference Example 1 A four-necked flask having an internal volume of 1 was equipped with a gas blow-in tube, a mechanical stirrer, and a dewar condenser.
After the inside of the reactor was replaced with deoxygenated dry nitrogen, 490 ml of degassed dry pyridine was placed in a four-necked flask, and cooled with ice. Then, when 51.6 g of dichlorosilane was added, a white solid adduct (SiH ₂ Cl ₂ .2C ₅ H ₅ N) was formed. The reaction mixture was ice-cooled, and while stirring, 51.0 g of purified ammonia was blown through a sodium hydroxide tube and an activated carbon tube.

After the completion of the reaction, the reaction mixture was centrifuged, washed with dry pyridine, and further filtered under a nitrogen atmosphere to obtain 850 ml of a filtrate. The solvent was distilled off from 5 ml of the filtrate under reduced pressure to obtain 0.102 g of a resin solid perhydropolysilazane.

The number average molecular weight of the obtained polymer was 980 as measured by GPC. When the IR (infrared absorption) spectrum (solvent: dry o-xylene; concentration of perhydropolysilazane: 10.2 g /) of this polymer is examined, the wave number (cm ⁻¹ ) is 3350 (apparent absorption coefficient ε = 0.557 lg). ^-1 c
m ^-1 ) and absorption based on NH at 1175; Si at 2170 (ε = 3.14)
Absorption based on H; It was confirmed to show absorption based on SiH and SiNSi of 1020 to 820. ¹ HNMR of this polymer
(Proton nuclear magnetic resonance) spectrum (60 MHz, solvent CDCl ₃
Investigation of the (reference material TMS) confirmed that all showed broad absorption. That is, δ4.8 and 4.4 (br, Si
H); 1.5 (br, NH) absorption was confirmed.

Reference Example 2 A reaction was carried out using the same apparatus as in Reference Example 1. That is,
500 ml of degassed dry dichloromethane was put into the four-necked flask shown in Reference Example 1, and this was cooled with ice. Next, 48.6 g of dichlorosilane was added. The solution was cooled on ice, and 42.5 g of purified ammonia was blown into the mixed gas with nitrogen through a sodium hydroxide tube and an activated carbon tube while stirring. During the reaction, fog was generated in the gas flow path, so that the gas flow path was occasionally tapped to prevent blockage.

When the reaction mixture was treated in the same manner as in Reference Example 1, 9.6 g of viscous oily perhydropolysilazane was obtained. The number average molecular weight of the obtained polymer was 640 as measured by GPC.

Reference Example 3 A reaction was carried out using the same apparatus as in Reference Example 1. That is,
450 ml of degassed dry tetrahydrofuran was placed in the four-necked flask shown in Reference Example 1, and cooled in a dry ice-methanol bath. Next, 46.2 g of dichlorosilane was added. The solution is cooled and stirred with anhydrous methylamine.
44.2 g was blown as a mixed gas with nitrogen.

After completion of the reaction, the reaction mixture was centrifuged, washed with dry tetrahydrofuran, and further filtered under a nitrogen atmosphere to obtain 820 ml of a filtrate. The solvent was distilled off under reduced pressure to obtain 8.4 g of viscous oily N-methylsilazane. The number average molecular weight of the obtained polymer was 1100 as measured by GPC.
Met.

Reference Example 4 A four-necked flask having an internal volume of 1 was equipped with a gas blow-in tube, a mechanical stirrer, and a dewar condenser.
After the inside of the reactor was replaced with deoxygenated dry nitrogen, 300 ml of dry dichloromethane and 24.3 g (0.211 mol) of methyldichlorosilane were placed in a four-necked flask and cooled with ice. While stirring, 18.1 g (1.06 mol) of purified ammonia was blown through a sodium hydroxide tube and an activated carbon tube.

After completion of the reaction, the reaction mixture was centrifuged, washed with dry dichloromethane, and filtered under a nitrogen atmosphere. The solvent was distilled off from the filtrate under reduced pressure to obtain 8.81 g of a colorless and transparent liquid. The number average molecular weight of this product was 380 as measured by GPC.

Reference Example 5 A reaction was carried out using the same apparatus as in Reference Example 1. That is, 450 ml of degassed dry benzene was put into the four-necked flask shown in Reference Example 1, and this was cooled with water. Next, 40.6 g of dichlorosilane was added. This solution was cooled with water, and while stirring, 42.0 g of purified ammonia was blown through a sodium hydroxide tube and an activated carbon tube as a mixed gas with nitrogen. During the reaction, fog was generated in the gas flow path, so that the gas flow path was occasionally tapped to prevent blockage.

When the reaction mixture was treated in the same manner as in Reference Example 1, 5.2 g of a viscous oily perhydropolysilazane was obtained. The number average molecular weight of the obtained polymer was 320 as measured by GPC.

Reference Example 6 A mechanical stirrer and a dewar condenser were used to drop a four-necked flask having an internal volume of 1. After replacing the inside of the reactor with deoxygenated dry nitrogen, a four-necked flask was degassed with 400 ml of degassed dry benzene and a known method (J. Am.
Chem. Soc, Vol. 67, 1813 (1945)). 64.5 g of allyldichlorosilane was added and stirred. A known method (J. Am. Chem. Soc. Vol 70,435 (1948))
42.5 g of triethylaminosilane obtained as described above and 50 ml of dry benzene were added. A benzene solution of triethylaminosilane was dropped into a benzene solution of allyldichlorosilane.
After completion of the dropwise addition, the mixture was heated and refluxed in an oil bath with stirring to carry out a reaction.

After completion of the reaction, the reaction mixture was centrifuged, washed with dry benzene, and then filtered under a nitrogen atmosphere to obtain 680 ml of a filtrate. When the solvent is removed from the filtrate, liquid N-
19.2 g of (triethylsilyl) alisilsilazane was obtained. The number average molecular weight of the obtained polymer was 360 as measured by GPC.

Reference Example 7 62.0 g of Grignard reagent synthesized from cyclohexyl bromide was slowly added to 110 g of trichlorosilane. After distillation under reduced pressure, 16.4 g of cyclohexyldichlorosilane was obtained. The same device as in Reference Example 6 was used.
12.0 g of cyclohexyldichlorosilane in a four-necked flask
And 420 ml of dry benzene were added and stirred. 1,1 for dripping funnel
15.6 g of dimethylhydrazine and 40 ml of dry benzene were charged. A benzene solution of 1,1-dimethylhydrazine was dropped into a benzene solution of cyclohexyldichlorosilane. After completion of the dropwise addition, the reaction was carried out while stirring at room temperature.

After completion of the reaction, the reaction mixture was centrifuged, washed with dry benzene, and then filtered under a nitrogen atmosphere to obtain 730 ml of a filtrate. When the solvent was removed from the filtrate, 3.2 g of oily N- (dimethylamino) cyclohexylsilazane was obtained. The number average molecular weight of the obtained polymer was 390 as measured by GPC.

Reference Example 8 A reaction was carried out using the same apparatus as in Reference Example 1. That is, 500 ml of degassed dry toluene was put into the four-necked flask shown in Reference Example 1, and this was cooled with ice. Next, 52.1 g of phenyldichlorosilane was added. This solution was cooled on ice, and while stirring, 30.0 g of purified ammonia was blown through a sodium hydroxide tube and an activated carbon tube as a mixed gas with nitrogen.

When the reaction mixture was treated in the same manner as in Reference Example 1, 6.8 g of oily phenylpolysilazane was obtained. The number average molecular weight of the obtained polymer was 380 as measured by GPC.

Example 1 A pyridine solution of perhydropolysilazane obtained in Reference Example 1 (concentration of perhydropolysilazane, 5.04% by weight) 1
00 ml was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and 2.8 g (0.165 mol) of purified anhydrous ammonia was added thereto.
The reaction was carried out while stirring for 3 hours. During this time, a large amount of gas was generated. The pressure increased by 1.2 kg / cm ² before and after the reaction.
After cooling to room temperature, 200 ml of dry o-xylene was added and the pressure was 3
After removing the solvent at 55 mmHg and a temperature of 50 to 70 ° C., 5.22 g of a white powder was obtained. This powder was soluble in toluene, tetrahydrofuran, chloroform and other organic solvents.

The number average molecular weight of the polymer powder was 3810 as measured by GPC. In addition, as a result of analysis of its IR spectrum (solvent: o-xylene), it was found that wave numbers (cm ⁻¹ ) of 3350 and 1175 were based on NH; 2170 were based on SiH;
It was confirmed to show absorption based on SiH and SiNSi of ~ 820. Further, ¹ HNMR spectrum (C
Analysis of (DCl ₃ , TMS) shows that all show broad absorption. That is, δ4.8 (br, SiH ₂ ), δ4.4 (br, SiH ₂ )
H ₃ ) and δ 1.5 (br, NH) were observed. (SiH ₂ ) /
(SiH ₃ ) = 4.1.

Example 2 A pyridine solution of perhydropolysilazane obtained in Reference Example 1 (concentration of perhydropolysilazane, 10.3% by weight) 8
0 ml was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, 4.1 g of purified anhydrous ammonia was added, and the reaction was carried out while stirring at 50 ° C. for 3 hours in a closed system. During this time, a large amount of gas was generated, and the gas was hydrogen as determined by gas chromatography (GC). The pressure rise before and after the reaction is 0.8 kg /
It was cm ^2. The solvent was distilled off under reduced pressure in the same manner as in Example 1 to obtain 8.1 g of a white powder, which was soluble in an organic solvent.

The number average molecular weight of the polymer powder was 2,290 as measured by GPC. In addition, ¹ HNMR of this polymer powder
The (SiH ₂ ) / (SiH ₃ ) ratio calculated from the spectrum was 4.3.

The elemental analysis results of the modified perhydropolysilazane obtained were as follows. (% By weight) Si: 59.9, N: 28.0, O: 1.42, C: 3.55, H: 5.21 The obtained modified perhydropolysilazane is stable,
Even after storage at room temperature under a nitrogen stream for one month, there was almost no change in its IR spectrum, ¹ H NMR spectrum and number average molecular weight.

Example 3 The modified perhydropolysilazane obtained in Example 1 was heated to 1000 ° C. at a heating rate of 10 ° C./min in nitrogen and thermally decomposed to give a brownish solid in a yield of 86.0% by weight. Obtained. X-ray powder diffraction measurement of the obtained ceramic confirmed that it was amorphous.

Next, this solid was further heated and fired at 1500 ° C. in nitrogen at a rate of 3 ° C./min to obtain a pale solid. It was subjected to a powder X-ray diffraction measurement of this material, 2 [Theta] + 20.5 ° α-Si ₃ N ₄ in (101) diffraction line, 2θ = 22,9 ° alpha-Si ₃ to N ₄ α-Si ₃ N ₄ (110) diffraction line, 2θ = 26.4 ° α-Si ₃ N ₄ (200) diffraction line, 2θ = 30.9 ° α-Si ₃ N ₄ (201) diffraction line, 2θ = 31.7 ° α − (002) diffraction line of Si ₃ N ₄ , 2θ = 34.5
Of DEG _{α-Si 3 N 4 (102} ) diffraction line, 2 [Theta] = 35.2 ° alpha-Si ₃ N
₄ (210) diffraction line, (211) diffraction line of α-Si ₃ N ₄ at 2θ = 38.8 °, (112) diffraction line of α-Si ₃ N ₄ at 2θ = 39.4 °, 2θ = 4
(300) diffraction line of α-Si ₃ N ₄ at 0.1 °, α-S at 2θ = 41.8 °
(202) diffraction line of i ₃ N ₄ , 2θ = 43.4 ° and α-Si ₃ N ₄ (30
1) Diffraction line, 2θ = 46.9 ゜, α-Si ₃ N ₄ (220) diffraction line, 2
(212) diffraction line of α-Si ₃ N ₄ at θ = 48.2 °, (310) diffraction line of α-Si ₃ N ₄ at 2θ = 48.8 °, and β− at 2θ = 23.3 °
Si ₃ N ₄ in (110) diffraction line, the 2 [Theta] = 26.9 ° β-Si ₃ N ₄ (20
0) Diffraction line, 2θ = 33.6 °, (101) diffraction line of β-Si ₃ N ₄
(210) diffraction line of β-Si ₃ N ₄ at θ = 36.0 °, (201) diffraction line of β-Si ₃ N ₄ at 2θ = 41.4 °, (310) diffraction line of β-Si ₃ N ₄ at 2θ = 49.9 ° ) Diffraction line, 2θ = 28.4 °, (111) diffraction line of Si, 2θ =
A (220) diffraction line of Si was observed at 47.3 °, confirming that the silicon nitride was crystalline silicon nitride.

The elemental analysis result of this crystalline silicon nitride is (wt%) Si: 5
8.1, N: 36.7, O: 1.42, C: 1.45.

Example 4 100 ml of a pyridine-o-xylene mixed solution of perhydroborisilazane obtained in Reference Example 1 (perhydropolysilazane concentration: 5.64% by weight, pyridine 50% by weight, o-xylene 50% by weight) was added to a 300 ml internal volume. 3.0 g of purified anhydrous ammonia was added to the pressure-resistant reaction vessel, and the reaction was carried out while stirring at 120 ° C. for 3 hours in a closed system. During this time, a large amount of gas was generated. The solvent was distilled off under reduced pressure in the same manner as in Example 1 to obtain 5.2 g of a modified polysilazane white powder. This modified polysilazane powder was soluble in an organic solvent, and its number average molecular weight was 4080 as measured by GPC.

Examples 5 to 7 The reaction was carried out in the same manner as in Example 1 except that the solvent, the concentration of perhydropolysilazane and the amount of ammonia (ammonia / perhydrosilazane (molar ratio)) indicated in Table 1 were used. A modified polysilazane was obtained. The properties are shown in Table 1.

Example 8 A pyridine solution of perhydropolysilazane obtained in Reference Example 2 (concentration of perhydropolysilazane, 3,87% by weight) 9
0 ml was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and 2.0 g of purified anhydrous ammonia was added thereto, and the reaction was carried out while stirring at 110 ° C. for 5 hours in a closed system. During this time, a large amount of gas was generated. The pressure increase before and after the reaction was 1.2 kg / cm ² . The solvent was distilled off under reduced pressure in the same manner as in Example 1 to obtain 3.7 g of a modified polysilazane white powder, which was soluble in an organic solvent. Its number average molecular weight, measured by GPC, was 3270. The ¹ H NMR spectrum of this modified polysilazane showed (SiH ₂ ) / (SiH ₃ ) = 5.8.

Example 9 A pyridine solution of perhydropolysilazane obtained in Reference Example 1 (concentration of perhydropolysilazane, 5.16% by weight) 1
00 ml was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and 1.5 ml of hydrazine anhydride was added while cooling in an ice bath. Gas evolution was observed immediately upon addition. The reaction was carried out with stirring at room temperature for 20 hours. A white powder of modified polysilazane was obtained by performing the same treatment as in Example 1 in which a pressure increase of 0.8 kg / cm ² was observed before and after the reaction, and its number average molecular weight by GPC was 5,690.

Example 10 100 ml of a pyridine solution of N-methylsilazane (concentration of N-methylsilazane, 4.56% by weight) obtained in Reference Example 3 was placed in a 300-ml pressure-resistant reaction vessel, and 3.8 g of purified anhydrous ammonia was added. The reaction was carried out while stirring at 120 ° C. for 3 hours in a closed system. During this time, a large amount of gas was generated. The pressure rose 0.7 kg / cm ² before and after the reaction. The solvent was distilled off under reduced pressure in the same manner as in Example 1 to obtain a pale yellow rubbery solid of modified polysilazane. Its number average molecular weight was measured by GPC and found to be 1
It was 350.

Example 11 According to Reference Example 4, 35 ml of a pyridine solution of polymethylsilazane (concentration of polymethylsilazane, 4.50% by weight) was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and 1.7 g of purified anhydrous ammonia was added. The reaction was carried out while stirring for 3 hours. During this time, gas generation was observed, and the pressure increased 0.4 kg / cm ² before and after the reaction. The solvent was distilled off under reduced pressure in the same manner as in Example 1 to obtain a pale yellow viscous liquid of modified polysilazane. Its number average molecular weight was measured by GPC and found to be 6
00.

Example 12 A pyridine solution of perhydropolysilazane obtained in Reference Example 5 (perhydropolysilazane concentration, 6.16% by weight)
100 ml was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and 2.1 g of purified anhydrous ammonia was added. The reaction was carried out while stirring at 100 ° C. for 8 hours in a closed system. During this time, a large amount of gas was generated.
The pressure increase before and after the reaction was 1.1 kg / cm ² . The solvent was distilled off under reduced pressure in the same manner as in Example 1 to obtain 5.3 g of a modified polysilazane white powder, which was soluble in an organic solvent. Its number average molecular weight was 2,470 as measured by GPC. The ¹ H NMR spectrum of this modified polysilazane was (SiH ₂ ) / (SiH ₃ ) = 6.8.

Example 13 The modified perhydrosilazane obtained in Example 2 was dried o
An o-xylene solution dissolved in xylene and containing 78% by weight of modified perhydropolysilazane was obtained. This was discharged from a nozzle into a heated atmosphere and wound up, whereby a colorless and transparent perhydrosilazane continuous fiber was obtained.

Example 14 100 ml of a pyridine solution of N- (triethylsilyl) allylsilazane obtained in Reference Example 6 (concentration of N- (triethylsilyl) allylsilazane, 5.64% by weight) was used to obtain an inner volume of 300 ml.
, 0.8 g of purified anhydrous ammonia was added, and the mixture was reacted while stirring at 100 ° C. for 5 hours in a closed system.
During this time, a large amount of gas was generated. The pressure before and after the reaction is 0.9 kg /
cm ² rose. The solvent was distilled off under reduced pressure in the same manner as in Example 1,
A pale yellow rubbery solid of the modified polysilazane was obtained. Its number average molecular weight was 940 as measured by GPC.

Example 15 N- (dimethylamino) cyclohexylsilazane pyridine solution (concentration of N- (dimethylamino) cyclohexylsilazane, 4.12% by weight) 100 m obtained in Reference Example 7
l was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and 0.6 g of purified anhydrous ammonia was added thereto. The mixture was reacted at 80 ° C. for 6 hours with stirring in a closed system. During this time, a large amount of gas was generated. The pressure increased 0.8 kg / cm ² before and after the reaction. The solvent was distilled off under reduced pressure in the same manner as in Example 1 to obtain a pale yellow rubbery solid of modified polysilazane. Its number average molecular weight was measured by GPC and found to be 1
080.

Example 16 The modified perhydropolysilazane obtained in Example 2 was heated to 1450 ° C in a mixed atmosphere of ammonia (50% by volume) and nitrogen (50% by volume) at a heating rate of 10 ° C / min, and was heated to 1450 ° C. 3
By calcining for a time, a pale brown solid was obtained in a yield of 87.2% by weight. When the obtained ceramics was subjected to powder X-ray diffraction measurement, it was confirmed that they were α-Si ₃ N ₄ and β-Si ₃ N ₄ .

Example 17 The modified perhydropolysilazane obtained in Example 4 was heated to 1500 ° C. at 5 ° C./min in hydrogen and calcined at 1500 ° C. for 5 hours to give a pale brown solid in a yield of 85.4% by weight. I got it.
When the obtained ceramics was subjected to powder X-ray diffraction measurement, it was confirmed that they were α-Si ₃ N ₄ and β-Si ₃ N ₄ .

Example 18 The modified polysilazane obtained in Example 10 was placed in a vacuum (3 to
The mixture was heated to 1600 ° C. at 3 ° C./min at 4 mmHg) and calcined at 1600 ° C. for 6 hours to obtain a black solid in a yield of 77.3% by weight. When the obtained ceramics was subjected to powder X-ray diffraction measurement, it was confirmed that they were α-Si ₃ N ₄ , β-Si ₃ N ₄ , and SiC (8F type).

Example 19 Phenylpolysilazane pyridine solution (concentration of phenylpolysilazane, 6.04% by weight) obtained in Reference Example 8 10
0 ml was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, 0.6 g of purified anhydrous ammonia was added, and the mixture was reacted while stirring at 120 ° C. for 6 hours in a closed system. During this time, a large amount of gas was generated. The pressure increased by 0.5 kg / cm ² before and after the reaction. The solvent was distilled off under reduced pressure in the same manner as in Example 1 to obtain a colorless transparent rubbery solid of modified polysilazane. Its number average molecular weight measured by GPC was 1090.

Example 20 Polymer powder produced by the method of Example 1 (number average molecular weight
3810), orthoxylene and silicon carbide (average particle diameter: about 10 microns) as a filler were added to prepare a solution of 30% by weight of polysilazane, 20% by weight of orthoxylene and 50% by weight of silicon carbide. SUS304 base (70mm × 30mm × 1mm
Spray was applied to the surface of t). After coating on the substrate, it was dried by heating at 400 ° C. for 1 hour in a drying furnace in an inert gas (nitrogen) atmosphere. The heating rate was 3 ° C./min. As a result, a film having a thickness of about 160 μm was obtained. Table 2 shows the performance of the coating.

 The inspection method is as follows.

A) Appearance: Cracks, color tone, and other defects of the coating film are examined by visual observation.

B) Pencil hardness: according to JIS K5400.

C) Adhesion: (Base peel test): 1m on steel coating with steel knife
After making 100 cuts at the base of the material that reaches m square, glue cellophane tape (Sekisui Chemical) on it,
The cellophane tape is evaluated by the number of squares remaining when the cellophane tape is strongly peeled upward in the direction of 90 °.

Example 21 A solution containing 25% by weight of polysilazane, 5% by weight of ortho-xylene, 70% by weight of silicon carbide, and 0.5% by weight of an auxiliary agent was prepared, applied to a substrate by brushing, and heated at 1000 ° C. under a nitrogen gas atmosphere.
When the coating was treated in the same manner as in Example 20 except that the coating was fired for an hour, the results shown in Table 2 were obtained as the coating.

Example 22 The method of Example 20 except that a solution of 50% by weight of polysilazane, 20% by weight of ortho-xylene and 30% by weight of silicon carbide was prepared, applied on SS41 by dipping, and baked at 200 ° C. for 1 hour in air. As a result, the results shown in Table 2 were obtained.

Comparative Example The viscous polysilazane obtained in Reference Example 2 [crosslinked NH
_n (n = 1 or 2), N / S ratio is less than 0.8, and number average molecular weight 640] was applied in the same manner as in Example 20, but sagging occurred and a film with sufficient hardness was not obtained. .

Example 23 A Si ₃ N ₄ sintered body was obtained in the same manner as in Example 1, except that modified polysilazane was used instead of inorganic polysilazane. The bulk density of this sintered body is 2.87 g / cm ³ , and the bending strength is 2
4.3 kg / cm ³ , exceeding the results of Examples 1 and 13.

Example 24 A SiC sintered body was obtained in the same manner as in Example 1, except that modified polysilazane was used instead of inorganic polysilazane. This sintered body had a bulk density of 2.83 g / cm ³ and a transverse rupture strength of 21.9 kg / mm ² , which exceeded the results of Examples 2 and 14.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C09J 183/16 JGE C09J 183/16 JGE

Claims (4)

(57) [Claims] 1. The compound has at least one kind of cross-linking represented by the following general formulas (A) to (D), and has an atomic ratio (N / Si) of nitrogen to silicon bonded to a silicon atom of at least 0.80. A modified polysilazane polymer having a number average molecular weight of 200 to 500,000. (In the formula, R ₁ and R ₂ represent an alkyl group, an alkenyl group, a cycloalkyl group, an alkylamino group, an aryl group, or an alkylsilyl group, and n is 1 or 2.) 2. The general formula (Wherein, R ₁ and R _{2 represent a} hydrogen atom, an alkyl group, an alkenyl group,
A polysilazane having a skeleton represented by a cycloalkyl group, an alkylamino group, an aryl group, or an alkylsilyl group) having a number average molecular weight of 100 to 50,000 and ammonia or hydrazine is subjected to a dehydropolycondensation reaction under basic conditions. The method for producing a modified polysilazane according to claim 1, wherein: 3. A coating agent comprising the modified polysilazane polymer according to claim 1 as an essential component. 4. A binder comprising the modified polysilazane polymer according to claim 1 as an essential component.