JP2613787B2 - Inorganic silazane high polymer, production method thereof and use thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high inorganic silazane polymer, a method for producing the same, and uses thereof. More specifically, the present invention relates to a high inorganic silazane which can be used as a precursor of silicon nitride and a silicon nitride-containing ceramic. The present invention relates to a polymer, a method for producing the polymer, and a coating agent and a binder containing the inorganic silazane high polymer as an essential component.

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 that high-purity α-type silicon nitride can be produced with 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, Vol.
38 No. 1, pp. 65-72 (1982)), this method has the disadvantage that silicon carbide and free carbon are formed 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, in the case of such combined polysilazane Stock _{is, - (SiH 2 NH) n} - at normal temperature only n = 7 to 8 of the oligomer having the structure of a viscous liquid, in the case of such Seyferth Is an oily liquid having a more complex structure than that of Stock et al. And having a proton ratio of Si-H / N-H of about 3.3, but heated at about 200 ° C. or left at room temperature for 3 to 5 days. Therefore, in any case of polysilazane, it cannot be said that the polysilazane has sufficient properties as a precursor for a shaped silicon nitride sintered body at normal temperature. .

Therefore, development of an inorganic silazane useful as a precursor of silicon nitride having higher molecular weight and spinnability and a method capable of synthesizing the same in a 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 more, when a silicone-based paint is used, it is necessary to reduce the crosslink density of the silicone resin. 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 inorganic silazane high polymer suitable as a silicon nitride precursor and a method for industrially producing the same, and a second object is to provide heat resistance, An object of the present invention is to provide a coating agent which is excellent in abrasion resistance and chemical resistance and can form a film having a high surface hardness. Still another object of the present invention is to provide a binder for a ceramic molded body, particularly a ceramic molded sintered body.

〔Constitution〕

According to the present invention, as a first invention, the number average molecular weight is
200 to 500,000, and the ratio of SiH ₃ groups to SiH ₂ groups in one molecule (S
iH ₂ groups / SiH ₃ groups) is 2.5 to 8.4, and the element ratio is
The present invention provides an inorganic silazane high polymer in which Si: 59% to 70% by weight, N: 20% to 34% by weight, and H: 5% to 9% by weight. The number average molecular weight is 200 to 500,000 characterized by heating in a basic solvent or a solvent containing a basic compound, and SiH _{3 in} one molecule
The ratio of the group to the SiH ₂ group (SiH ₂ group / SiH ₃ group) is 2.5 to 8.4, and the element ratio is Si: 59% to 70% by weight, N: 20% to 34% by weight, H: A method for producing an inorganic silazane polymer having a weight average molecular weight of 200 to 500,000 and a SiH content in one molecule is provided as a third invention.
The ratio of _three groups to SiH ₂ groups (SiH ₂ groups / SiH ₃ groups) is 2.5 to 8.4, and the element ratio is Si: 59% to 70% by weight, N: 20% to 34% by weight, : A coating agent containing an inorganic silazane high polymer in an amount of 5 to 9% by weight as an essential component is provided. Further, as a fourth invention, the number average molecular weight is 200 to 500.
000, and the ratio of SiH ₃ groups to SiH ₂ groups in one molecule (SiH ₂ groups / SiH
A H ₃ group) is 2.5 to 8.4, yet elemental ratio Si: 59 wt% to 70 wt%, N: 20 wt% to 34 wt%, H: 5% to
A binder containing an inorganic silazane high polymer of 9% by weight as an essential component is provided.

The raw material inorganic silazane used as a starting material for the inorganic silazane high polymer of the present invention has a skeleton represented by the following general formula.

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

The inorganic silazane 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 → SiH 2 NH n + 2NH 4 Cl + 2Py In the present invention, the inorganic silazane as the starting material is heated in a basic solvent or a solvent to which a basic compound has been added to cause a dehydrogenation polycondensation reaction (hereinafter, also simply referred to as a polycondensation reaction). In this case, as the basic compound, a compound containing a basic element such as nitrogen or phosphorus, for example,
Secondary amines, secondary amines having a sterically hindered group,
Phosphine or the like can be used. The reaction solvent used in the present invention is a solvent obtained by adding such a basic compound to a non-basic solvent or a solvent consisting of the basic compound itself. When the basic compound is added to the non-basic solvent, the amount of the basic compound added is at least 5 parts by weight, preferably 20 parts by weight or more based on 100 parts by weight of the non-basic solvent.
If the amount of the basic compound is less than this, the polycondensation reaction is not smoothly promoted.

As the basic compound or basic solvent, any one can be used as long as it does not decompose the inorganic silazane as a starting material. Such compounds include, for example, tertiary amines such as trialkylamines such as trimethylamine, 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, halogenated hydrocarbons 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 carried out in a solvent as described above.In this case, the concentration of the raw material inorganic silazane in the solvent is 0.
It is 1% to 50% by weight, preferably 1% to 12% by weight. When the concentration of the inorganic silazane is lower than this, the intermolecular polycondensation reaction does not sufficiently proceed, and when it is higher than this, the gel is generated due to excessive progress of the intermolecular polycondensation reaction. The reaction temperature is from −78 ° C. to 300 ° C., preferably from −40 ° C. to 200 ° C. At a lower temperature, the polycondensation reaction does not proceed sufficiently,
At a higher temperature, the polycondensation reaction proceeds too much to form a gel. As the reaction atmosphere, air can be used, but preferably, a hydrogen atmosphere, an inert gas atmosphere such as dry nitrogen or dry argon, or a mixed atmosphere thereof is used. In the polycondensation reaction of the present invention, pressure is applied during the reaction due to hydrogen as a by-product, but pressurization is not necessarily required, and normal pressure can be employed. The reaction time varies depending on various conditions such as the type and concentration of the inorganic silazane as the starting material and the type and concentration of the basic compound or the basic solvent, and the polycondensation reaction temperature, but generally ranges from 0.5 hours to 20 hours. That is enough.

Optimum conditions for the polycondensation reaction differ depending on the average molecular weight, molecular weight distribution, and the like of the starting inorganic silazane. 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 polycondensation reaction of the present invention, an inorganic silazane high polymer, that is, a solvent solution containing a high molecular weight inorganic silazane is obtained.In this case, by adjusting the solution composition,
30% by weight of basic compound or basic solvent in all solvents
Or less, preferably 5% by weight or less. Since the basic compound or the basic solvent acts as a catalyst for the intermolecular polycondensation reaction of the inorganic silazane high polymer, if the ratio to the total solvent becomes too large, a gel is generated during long-term storage at room temperature. I do. The adjustment of the solution composition can be performed, for example, by evaporating the inorganic silazane high polymer solution obtained by the polycondensation reaction to remove the basic compound or the solvent contained therein by evaporation and then removing the non-basic (non-reactive ) Can be carried out by adding a solvent. When the content of the basic compound in the solution is high, or when the basic compound itself is used as the reaction solvent, by performing a solution composition adjustment operation including the above-described evaporation and removal of the basic compound and addition of a non-basic solvent. A stable solution composition can be obtained. In the present invention, the non-basic solvent for forming a stable solution of the inorganic silazane high polymer includes aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, and aliphatic hydrocarbons as described above. Group ethers, alicyclic ethers and the like can be used.

The polycondensation reaction of the inorganic silazane in the present invention is considered to include the following elementary reaction.

(1) In the general formula (I), The inorganic silazane high polymer of the present invention is a polymer produced by the polycondensation reaction of the raw material inorganic silazane as described above, and has a high molecular weight due to a new cross-linking occurring in the inorganic silazane molecule. That is, the inorganic silazane high polymer of the present invention has a number average molecular weight of 100 to 50,000 as described above.
Is formed by using an inorganic silazane as a raw material and cross-linking it into a polymer, so that its molecular weight is
Naturally, the molecular weight of the starting inorganic silazane is increased. In general, the inorganic silazane high polymer intended for the present invention has a number average molecular weight of 200 to 500,000,
Preferably, it has between 1,500 and 10,000.

The inorganic silazane high polymer of the present invention has the characteristics as described above in terms of molecular structure and is distinguished from the raw material inorganic silazane, but in addition, it has many branched structures. One. Due to this branched structure, the inorganic silazane high polymer of the present invention has a higher molecular weight than the raw inorganic silazane, but gives improved results in solvent solubility. For example, the inorganic silazane previously proposed by Seyferth et al. Is an oily liquid having a proton ratio of -Si-H / N-H of about 3.3, but is heated at about 200 ° C or left at room temperature for 3-5 days. This caused the solidification. On the other hand, the inorganic silazane high polymer of the present invention has a molecular weight of 200 to 500,000, and the number of SiH ₃ groups in one molecule usually increases twice or more as compared with the raw material inorganic silazane, thereby reducing solvent resolubility. Have. The reason that the inorganic silazane high polymer of the present invention has a more branched structure than the raw material inorganic silazane is that, in the polycondensation reaction of the present invention, in addition to the polycondensation reaction, for example, the following reaction is performed. It is thought to be caused.

The branched structure of the inorganic silazane high polymer of the present invention can be obtained by, for example, ¹ HNMR spectrum measurement, (SiH ₂ ) / (S
iH ₃ ) [(SiH ₂ ): 1 / of the area of the Si-H resonance at δ 4.8
2, (SiH _3): it can be evaluated by 1/3] ratio of SiH resonance area in Deruta4.4. In the case of the raw inorganic silazane, the (SiH ₂ ) / (SiH ₃ ) ratio is in the range of 5.0 to 19.0, but in the case of the inorganic silazane high polymer of the present invention,
This is a reduced value of 2.5 to 8.4. If the SiH ₂ / SiH ₃ ratio of the inorganic silazane high polymer is not in the above range, the solidification properties and the shapeability are poor, and the intended object of the present invention cannot be achieved.

The inorganic silazane high polymer of the present invention has the molecular structural characteristics as described above, and is physically soluble in an organic solvent while having a cross-linking bond, and is particularly obtained by removing the solvent from the solution. The obtained solid polymer has a great feature of having resolubility in a solvent. In the case of the conventional inorganic silazane, 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 inorganic silazane high polymer of the present invention has such a tendency. Is not shown. Therefore, in the case of the conventional inorganic silazane, it was impossible or extremely difficult to handle it as a solid polymer, whereas the inorganic silazane high polymer of the present invention can be easily handled as a solid polymer.

Further, the inorganic silazane high polymer of the present invention has an element ratio of Si: 5
9% to 70% by weight, N: 20% to 34% by weight, H: 5% by weight
-9% by weight.

The preferred element ratio of the inorganic silazane high polymer of the present invention is
Si: 61% to 68% by weight, N: 25% to 33% by weight, H: 5% to 8% by weight, and a more preferable element ratio is Si: 64%.
Wt% to 68 wt%, N: 27 wt% to 33 wt%, H: 5 wt%
~ 7% by weight.

If the elemental ratio of the inorganic silazane high polymer does not satisfy the above range, it is difficult to handle it as a solid polymer, and the intended object of the present invention cannot be achieved.

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

When these solvents are used, two or more kinds of solvents may be mixed in order to adjust the solubility of the inorganic silazane high polymer and the evaporation rate of the solvent. Amount of solvent used (ratio)
Is selected so that the workability is improved by the coating method employed.Although it depends on the average molecular weight, molecular weight distribution and structure of the inorganic silazane high polymer, the solvent in the coating agent can be mixed up to about 90% by weight,
Preferably, it can be mixed in the range of 10% by weight 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 to 10 parts by weight, and particularly preferably 0.2 to 3 parts by weight, based on 1 part by weight of the inorganic silazane high polymer.
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 dissolves uniformly,
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. In addition, if the substrate is sanded, degreased, or surface-treated with various types of blasting before application, 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 inorganic silazane high polymer is cross-linked, condensed and cured to form a tough coating.

The above calcination conditions vary depending on the molecular weight and structure of the inorganic silazane high polymer, but are controlled at a gradual heating rate of 0.5 to 10 ° C / min.
Baking at a temperature in the range of 00C to 1000C. Preferred firing temperatures range 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 inorganic silazane high polymer as a binder, the following method is usually used.
That is, the inorganic silazane high polymer is soluble in an organic solvent such as xylene.

Therefore, by adding and mixing various ceramic powders and an inorganic silazane high polymer into such a solvent, it is possible to easily and uniformly disperse them as a binder in the ceramic powders. Here, since the inorganic silazane high polymer also acts as a peptizer (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 inorganic silazane high polymer is thermally decomposed, hydrogen is volatilized, and highly active Si and N react with the ceramic particles to form a binder for sintering. And strongly binds 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. An inorganic silazane high polymer that does not have a high purity Si ₃ N ₄ composition after pyrolysis can be said to be a preceramic polymer suitable as a binder for sintering. In addition, since the form of Si ₃ N ₄ usually fills the space between ceramic particles in the form of amorphous or extremely small crystal particles of 1000 ° or less, it also serves 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 inorganic silazane high polymer added can be increased or decreased without limitation according to the properties 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 form ceramics using such a binder, as described above, a ceramic powder and an inorganic silazane high polymer are added to a solvent and mixed to form a slurry, and the slurry is formed. May be evaporated to form granulated powder and press-molded.

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 inorganic polysilazane acts as a molding binder for granulation and, at the same time, is uniformly mixed in the ceramic powder as a sintered 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 inorganic silazane high polymer is dissolved in a solvent, and the ceramic molded body (sintered body) is impregnated with the inorganic silazane high polymer. By firing the body, the ceramic molded body (sintered body) can be densified.

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 ethylidene chloride, trichloroethane, tetrachloroethane, ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-dioxyethane, dioxane , Dimethyldioxane, tetrahydrofuran, 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 turn the inorganic silazane high polymer into ceramics, and a ceramic molded sintered body can be obtained. The firing conditions are vacuum, inert gas,
Heat sintering is performed within a temperature range of 600 to 2300 ° C. in an atmosphere composed of at least one selected from a reducing gas and a hydrocarbon gas.

The sintered body obtained in this manner has a structure formed by amorphous or extremely fine particles of 1000 ° or less, which are generated by heating and decomposing 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 inorganic silazane high polymer of the present invention has the molecular structural and physical characteristics as described above, and can be used in various fields. Next, the application and production characteristics of the inorganic silazane high polymer of the present invention will be described.

The inorganic silazane high polymer is soluble in an organic solvent,
Since it can be converted to silicon nitride or silicon nitride-containing ceramics by firing, it has a high-performance ceramic molded body, that is, continuous fibers, films, and coatings with high mechanical strength at high temperatures and excellent heat resistance, corrosion resistance, oxidation resistance, and thermal shock resistance. A covering film 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.

Inorganic silazane high polymer does not contain impurities such as residual catalyst that promotes decomposition in the polymer, so stability is improved, handling is easy, and the purity of ceramics after high temperature firing is improved. I do.

Since the inorganic silazane high polymer has a crosslinked structure and a higher molecular weight than the raw material inorganic silazane, the solidification property is improved,
Immediate shaping can be performed 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 polymer, 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 an inorganic silazane high polymer, 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 gas blow-in tube, a mechanical stirrer, and a dewar condenser were installed in a four-necked flask having an inner volume of 500 ml. After the inside of the reactor was replaced with deoxygenated dry nitrogen, 280 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 30.0 g of purified ammonia was blown through a sodium hydroxide tube and an activated carbon tube while stirring.

After completion of the reaction, the reaction mixture was centrifuged, washed with dry pyridine, and then filtered under a nitrogen atmosphere to obtain 520 ml of a filtrate. The solvent was distilled off from 5 ml of the filtrate under reduced pressure to obtain 0.98 g of a resinous solid inorganic silazane.

The number average molecular weight of the obtained polymer was 1020 as measured by GPC. When the IR (infrared absorption) spectrum of this polymer (solvent: dry o-xylene; concentration of inorganic silazane: 9.8 g /) is examined, the wave number (cm ^-1 ) 33
Absorptions based on NH of 50 and 1175; absorptions based on SiH of 2170 (ε = 3.14); absorptions based on SiH and SiNSi of 1020-820 were confirmed. When the ¹ H NMR (proton nuclear magnetic resonance) spectrum (60 MHz, solvent CDCl ₃ / standard substance TMS) of this polymer was examined, it was confirmed that each of them showed a broad absorption. That is, δ 4.8 and 4.4 (br, SiH); 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,
260 ml of degassed dry dichloromethane was put into the four-necked flask shown in Reference Example 1, and this was cooled with ice. Next, 25.0 g of dichlorosilane was added. The solution was cooled on ice, and while stirring, 22.3 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, 4.9 g of a viscous oily inorganic silazane was obtained. The number average molecular weight of the obtained polymer was 620 as measured by GPC.

Reference Example 3 A reaction was carried out using the same apparatus as in Reference Example 1. That is, 300 ml of degassed dry benzene was placed in the four-necked flask shown in Reference Example 1, and this was cooled with water. Next, 24.0 g of dichlorosilane was added. This solution was cooled with water, and while stirring, 23.8 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, fine particles were formed in the gas flow path, so that the gas flow path was sometimes beaten to prevent clogging.

When the reaction mixture was treated in the same manner as in Reference Example 1, 3.1 g of a viscous oily inorganic silazane was obtained. The number average molecular weight of the obtained polymer was 360 as measured by GPC.

Example 1 100 ml of the pyridine solution of inorganic silazane (concentration of inorganic silazane, 5.24% by weight) obtained in Reference Example 1 was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and was placed under a nitrogen atmosphere in a closed system at 150 ° C. for 3 hours.
The reaction was performed with stirring for hours. During this time, a large amount of gas was generated. The pressure increased by 1.0 kg / cm ² before and after the reaction. After cooling to room temperature, 200 ml of dry ethylbenzene was added, and the pressure was 3-5.
After removing the solvent at mmHg and a temperature of 50 to 70 ° C., 4.68 g of a white powder was obtained. This powder was soluble in toluene, tetrahydrofuran, chloroform and many other organic solvents.

The number average molecular weight of the polymer powder was 2,470 as measured by GPC. As a result of analyzing the IR spectrum (solvent: ethylbenzene), the wave number (cm ⁻¹ ) of 3350
And 1175 based on NH; 2170 based on SiH; 1
It was confirmed to show absorption based on SiH and SiNSi of 020-820. Further, when the ¹ H NMR spectrum (CDCl ₃ , TMS) of the polymer powder was analyzed, each of them showed a broad absorption. That is, δ4.8 (br, SiH ₂ ), δ4.4 (br,
SiH ₃ ) and δ1.5 (br, NH) were observed. (SiH ₂₎
/ (SiH ₃ ) = 4.1.

Example 2 200 ml of the pyridine solution of inorganic silazane (concentration of inorganic silazane, 6.18% by weight) obtained in Reference Example 1 was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and was placed under a nitrogen atmosphere in a closed system at 120 ° C. for 3 hours.
The reaction was carried out with stirring for hours. During this time, a large amount of gas was generated, and the gas was hydrogen as determined by gas chromatography (GC). The pressure increase before and after the reaction was 2.0 kg / cm ² . After cooling to room temperature, 400 ml of dry o-xylene was added, the solvent was removed at a pressure of 3 to 5 mmHg and a temperature of 50 to 70 ° C., to obtain 10.9 g of a white powder, which was soluble in an organic solvent.

The number average molecular weight of the polymer powder was 1,950 as measured by GPC.

Elemental analysis results of the obtained modified inorganic silazane high polymer were as follows. (% By weight) Si: 62.7, N: 25.7, O: 3.52, C: 4.4, H: 5.00 Example 3 The inorganic silazane high polymer obtained in Example 2 was dissolved in nitrogen.
The mixture was heated to 1400 ° C. at a heating rate of 3 ° C./min and calcined for 3 hours to obtain a brownish powder in a yield of 79.6% by weight. When the powder X-ray diffraction measurement of the obtained ceramics was performed,
2 [Theta] = 20. ° α-Si ₃ N ₄ in (101) diffraction line, the 2 [Theta] = 22.9 ° _{α-Si 3 N 4 (110} ) diffraction line, 2 [Theta] = 26.4 ° α-Si ₃ N ₄
(200) diffraction line of α-Si ₃ N ₄ at 2θ = 30.9 °, (002) diffraction line of α-Si ₃ N ₄ at 2θ = 31.7 °, 2θ = 3
(102) diffraction line of α-Si ₃ N ₄ at 4.5 °, α-S at 2θ = 35.2 °
(210) diffraction line of i ₃ N ₄ , α-Si ₃ N ₄ (21
1) Diffraction line, (112) diffraction line of α-Si ₃ N ₄ at 2θ = 39.4 °,
2 [Theta] = 40.1 ° α-Si ₃ N ₄ in (300) diffraction line, the 2 [Theta] = 41.8 ° _{α-Si 3 N 4 (202} ) diffraction line, 2 [Theta] = 43.4 ° α-Si ₃ N ₄
(301) diffraction line of α-Si ₃ N ₄ at 2θ = 46.9 ゜) 220) diffraction line of α-Si ₃ N ₄ at 2θ = 48.2 ゜, 2θ = 4
(310) diffraction line of α-Si ₃ N ₄ at 8.8 °, and 2θ = 23.3
Of DEG _{β-Si 3 N 4 (110} ) diffraction line, 2 [Theta] = 26.9 ° β-Si ₃ N
₄ (200) diffraction line, β-Si ₃ N ₄ (101) diffraction line at 2θ = 33.6 °, 2θ = 36.0 ° β-Si ₃ N ₄ (210) diffraction line, 2θ = 4
(201) diffraction line of β-Si ₃ N ₄ at 1.4 °, β-S at 2θ = 49.9 °
(310) diffraction line of i ₃ N ₄ , (111) diffraction line of Si at 2θ = 28.4 °, (220) diffraction line of Si at 2θ = 47.3 °, confirming that it is crystalline silicon nitride Was done.

 The results of elemental analysis of this crystalline silicon nitride were (% by weight): Si: 63.8, N: 28.7, O: 2.17, C: 0.36, H: 0.11.

Example 4 120 ml of the α-picoline solution of the inorganic silazane obtained in Reference Example 1 (concentration of inorganic silazane, 5.86% by weight) was placed in an internal volume of 300 m.
The reaction mixture was placed in a pressure-resistant reaction vessel (1) and stirred at 120 ° C. for 3 hours in a closed system under a nitrogen atmosphere. During this time, a large amount of gas was generated. When the solvent was distilled off under reduced pressure in the same manner as in Example 2, 6.22 g of a white powder of an inorganic silazane high polymer was obtained. This powder was soluble in an organic solvent, and its number average molecular weight was 1,850 as measured by GPC.

Example 5 100 ml of the pyridine solution of inorganic silazane (concentration of inorganic silazane, 7.25% by weight) obtained in Reference Example 2 was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and placed in a nitrogen atmosphere at 120 ° C. in a closed system under a closed atmosphere.
The reaction was performed with stirring for hours. 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 2 to obtain 6.43 g of a white powder of a high inorganic silazane polymer. This powder is soluble in organic solvents and its number average molecular weight is GPC
Was 2030.

Example 6 100 ml of the pyridine solution of inorganic silazane (concentration of inorganic silazane, 10.3% by weight) obtained in Reference Example 3 was placed in a pressure-resistant reaction vessel having an internal volume of 300 ml, and placed in a nitrogen atmosphere and a closed system at 120 ° C.
The inside was performed while stirring for an hour. During this time, a large amount of gas was generated. When the solvent was distilled off under reduced pressure in the same manner as in Example 2, 9.15 g of a white powder of an inorganic silazane high polymer was obtained. This powder was soluble in an organic solvent, and its number average molecular weight by GPC was 1,880.

Example 7 The inorganic silazane high polymer obtained in Example 2 was dissolved in dry toluene to obtain a toluene solution containing 82% by weight of the inorganic silazane high polymer. This was discharged from a nozzle into a heated atmosphere and wound up to obtain a colorless and transparent inorganic silazane high polymer continuous fiber.

Example 8 Ortho-xylene and silicon carbide (average particle diameter of about 10 microns) were added to the inorganic silazane high polymer powder (number average molecular weight 2470) produced by the method of Example 1, and 45% by weight of inorganic silazane was added. A solution of 25% by weight of ortho-xylene and 30% by weight of silicon carbide was prepared. This is SS41 base (70mm ×
30 mm x 1 mmt) was applied by spraying. After coating on the substrate, dry in an inert gas (nitrogen) atmosphere
C. and dried by heating for 1 hour. The heating rate was 3 ° C./min.
As a result, a film having a thickness of about 160 μm was obtained. Table 1 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 (substrate peeling test): 1 mm with a steel knife on the coating film
After making 100 cuts at the base of the material on each side, gluing 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 9 A solution containing 25% by weight of an inorganic silazane high polymer, 15% by weight of ortho-xylene, 60% by weight of silicon carbide, and 0.5% by weight of an auxiliary agent was prepared, applied to a SUS304 substrate by brushing, and heated at 00 ° C. under a nitrogen gas atmosphere. Except for baking for 1 hour, the coating was treated in the same manner as in the example, to obtain a coating as shown in Table 1.

Example 10 90% by weight of an inorganic silazane high polymer and ortho-xylene 10
Weight% solution, apply by dipping on SUS304,
Except for baking in air at 400 ° C. for 1 hour, the coating was treated in the same manner as in Example 8 to obtain a coating as shown in Table 1.

Example 11 A Si ₃ N ₄ sintered body was obtained in exactly the same manner as in Example 1, except that the inorganic silazane high polymer of Example 1 was used instead of using the inorganic polysilazane. The bulk density of this sintered body is 2.75 g
/ cm ³ , the transverse rupture strength was 18.2 kg / mm ² , and a sintered body with higher density and higher strength was obtained than in Example 1.

Example 12 A SiC sintered body was obtained in exactly the same manner as in Example 2 except that an inorganic silazane high polymer was used instead of using inorganic polysilazane. The bulk density of this sintered body was 2.75 g / cm ² , and the transverse rupture strength was 16.4 kg / mm ² , surpassing the results of Example 2.

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Claims (4)

(57) [Claims] (1) The number average molecular weight is from 200 to 500,000, and the ratio of SiH ₃ groups to SiH ₂ groups in one molecule (SiH ₂ groups / SiH ₃ groups) is 2.5 to 8.
4, and the element ratio is 50: 70% by weight of Si:
N: 20 wt% to 34 wt%, H: 5 wt% to 9 wt%, an inorganic silazane high polymer. 2. The method for producing a high inorganic silazane polymer according to claim 1, wherein the inorganic silazane is heated in a basic solvent or a solvent containing a basic compound. 3. A coating agent comprising the inorganic silazane high polymer according to claim 1 as an essential component. 4. A binder comprising the inorganic silazane high polymer according to claim 1 as an essential component.