JPH01138108A - Inorganic silazane high-polymer, its production and use thereof - Google Patents

Abstract

PURPOSE:To obtain a suitable silicon nitride precursor having specific mol.wt., SiH2/SiH3 ratio, Si, N and H contents and obtain a coating agent, etc., having excellent heat-resistance, etc., by heating an inorganic silazane in a basic solvent, etc. CONSTITUTION:A high-polymer of an inorganic silazane having a number- average mol.wt. of 200-500,000, a radio of SiH2 group/SiH3 group of 2.5-8.4 in 1mol. and containing 50-70wt.% of Si, 20-34wt.% of N and 5-9wt.% of H can be produced by heating an inorganic silazane in a basic solvent or a solvent containing a basic compound. A coating agent or a binder can be produced by using the polymer as an essential component.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an inorganic silazane polymer, a method for producing the same, and its uses, and more specifically, an inorganic silazane that can be used as a precursor for silicon nitride and silicon nitride-containing ceramics. The present invention relates to a high polymer, a method for producing the same, and a coating agent and binder containing the inorganic silazane high polymer as an essential component.

Conventionally, methods for producing silicon nitride include: heating metal silicon powder at 1300°C to 150°C in a nitrogen or ammonia stream;
Silicon direct nitriding method, which heats at 0°C and directly nitrides,■
A silica reduction method in which silica or a silica-containing substance is heated together with carbon in a nitrogen atmosphere, the silica is reduced with urea, and the resulting silicon reacts with nitrogen. ■ A method in which silicon tetrachloride and ammonia are directly reacted at high temperatures. Phase synthesis method, (2) imide thermal decomposition method in which silicon diimide obtained by ammonolysis of silicon tetrachloride is heated in a non-oxidizing atmosphere to obtain silicon nitride, etc. are employed.

However, in the case of method (2) above, the reaction time is long, the heating process is complicated, and the silicon nitride obtained is mainly β-type silicon nitride that is coarse and contains many impurities. is 1. Not only is it difficult to purify the raw materials, the reaction time is long, and the product obtained is a mixed system of α-type silicon nitride and β-type silicon nitride. It is crystalline, and in the case of method ■,
Although it has the advantage of being able to produce high-purity α-type silicon nitride with good yield, the silicon diimide (Si(NH))x, which is a silicon nitride precursor, is not soluble in solvents, so its uses are essentially limited. There were some unavoidable drawbacks.

Furthermore, a method has recently been proposed in which silicon nitride is synthesized by heating polysilazane obtained by thermally decomposing organic polysilazane at 800 to 2000°C (Hajime Saito, Journal of the Japan Institute of Textile Technology)
VoQ38Nal pages 65-72 [1982])
However, this method has the disadvantage that silicon carbide and free carbon are produced simultaneously with silicon nitride.

On the other hand, inorganic polysilazane is soluble in solvents.

5tack in 1921 (Ber, 54. (1921)
, p740), etc., and in 1983, 5eyferth (Go+am, Am, Cera
m, soc, c-13/14. (g3)) etc., it has been proven that this is useful as a silicon nitride precursor. The present inventors focused on this point of view and proposed a method for obtaining highly pure α-type silicon nitride by heat-treating inorganic polysilazane (Japanese Patent Application Laid-Open No. 59-207812
issue).

However, in the conventional manufacturing method of inorganic polysilazane, since highly volatile dichlorosilane is used as a raw material in all cases, the polysilazane produced sticks to the gas piping or the reactor wall of the reactor and damages the gas flow path. - In order to prevent the above-mentioned adverse effects, it is necessary to maintain the reaction temperature at a low temperature to prevent dichlorosilane from scattering. - Dichlorosilane is highly toxic and flammable, so it should not be stored in a closed container at low temperatures. There were disadvantages such as complicated handling, such as having to put it in and use it. Furthermore, in the case of 5tack etc., the synthesized polysilazane is -(SiHJH)n
It is only an oligomer of n=7 to 8 having a structure of - and is a viscous liquid at room temperature.
It is an oily liquid with a -H/N-H proton ratio of about 3.3, but it solidifies by heating at about 200°C or leaving it at room temperature for 3 to 5 days. Even in the case of sintered silicon nitride, it could not be said that it had sufficient properties as a precursor for a silicon nitride sintered body shaped at room temperature.

Therefore, it has been desired to develop an inorganic silazane useful as a precursor of silicon nitride having a higher molecular weight and stringiness, and a method for easily synthesizing this inorganic silazane with higher yield.

On the other hand, coating agents for the surfaces of metal and inorganic materials include silicone paints, polytitanocarbosilane paints, and even poly(disilyl)silazane polymers (Special Publications No. 6).
1-38933) is known.

However, although silicone paints provide a film with excellent heat resistance even in high-temperature atmospheres of 200°C or higher, they tend to generate pinholes, and in order to prevent the formation of pinholes, the film thickness of the film must be increased. Cracks, blisters, or peeling may occur in the coating during firing. This phenomenon is particularly noticeable at temperatures above 300°C, so when using silicone paints, it is necessary to reduce the crosslinking density of the silicone resin, which reduces the surface hardness of the formed film. This poses a problem.

In addition, polytitanocarbosilane paints are fired at low temperatures (40
The disadvantages are that the surface hardness at temperatures below 0° C. is not sufficient, the raw material manufacturing process is complicated, and the manufacturing cost is high.

Furthermore, the method using a poly(disyl)silazane polymer requires a process of thermal decomposition at a high temperature of 750° C. or higher in an inert atmosphere or in a vacuum.

There are many difficulties in its implementation. Similarly, a report has been made on a silicon nitride coating film obtained from polysilazane, but cracks occur and a film with sufficient practical value has not been obtained (LS, CobliB et al.
al, “Formation of Ceramic
Compositions Utilizing Po
lymer pyrolysis”.

P271-285, Materials 5cienc
eRe5earch vaultEmergent
Process Methods For High-
Technology Ceramics edit
d by R, F, Davis et, al, P
lenunPress N, Y,).

〔the purpose〕

The first object of the present invention is to provide a novel inorganic silazane polymer suitable as a silicon nitride precursor and an industrially advantageous method for producing the same, and the second object is to provide heat resistance, It is an object of the present invention to provide a coating agent that has excellent abrasion resistance and chemical resistance and can form a film with high surface hardness. A third object is to provide a binder for ceramic molded bodies, particularly ceramic molded sintered bodies.

[Oval formation]

According to the present invention, as the first invention, the number average molecular weight is 2.
00 to 500,000, and the SiH group in one molecule and 5
The ratio of i82 groups (SiH, group/5iHi group) is 2.5 to 8
．． 4, and the element ratio is Si: 59% by weight to 7
0% by weight, N: 20% by weight 2-34% by weight, H: 5% by weight
A second invention provides an inorganic silazane high polymer having a number average molecular weight of 200 to 9% by weight, characterized in that the inorganic silazane is heated in a basic solvent or in a solvent containing a basic compound. 500,000, and S in one molecule
The ratio of iH, groups to S i H, groups (SiH, groups / Si
t (group) is 2.5 to 8.4, and the element ratio is Si: 59% to 70% by weight, N: 20% by weight to
34% by weight, 11:5% by weight X to 9% by weight and the ratio of 5i82 groups (SiH, groups/SiH
3) is 2.5 to 8.4, and the element ratio is S
i: 59% to 70% by weight, N: 20% to 34% by weight
A coating agent is provided which contains an inorganic silazane high polymer as an essential component, with f% and H: 5% to 9%. Furthermore, as a fourth invention, the number average molecular weight is 200 to 5000.
00, the ratio of SiH groups to 5it (□ groups (Si2 groups/5iHz groups) in one molecule is 2.5 to 8.4, and the element ratio is Si: 59% to 70% by weight %, N
Provided is a binder containing an inorganic silazane high polymer as an essential component: 20% to 34% by weight and H: 5% to 9% by weight.

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 a cyclic inorganic silazane, a chain inorganic silazane, or a mixture thereof.

The raw material inorganic silazane preferably used in the present invention has a number average molecular weight of 300 to 2000, preferably 600 to 1.
400 chain inorganic silazane.

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

■ Inventor's patent issued WL (Jikai 60-1.45903)
・SiH□CQ 2+2Py −+ SiH,CQ2・
2Py adduct・5iH2CQ,・2Pyadd
uct+3NH, -+ -(SiH2NH mostly +2NH
, CQ +2P, y■ D, 5eyferth et al. (U
SP 4,397,828) CI2CQ.

・5i82CQ 2+3NH3−→ −(Si)12N
)I+t1+2NH,Cα■ A, 5tack (B
er, 54. (1921), P-740) ■ W
2N, 5cantlin et al., Inorg, Che
w, 1972.11 In the present invention, the inorganic silazane, which is 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, such as tertiary amines, secondary amines having a sterically hindered group, phosphine, etc. 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 adding a basic compound to a non-basic solvent, the amount of the basic compound added is at least 5 parts by weight, preferably 2 parts by weight, per 100 parts by weight of the non-basic solvent.
It is 0 parts by weight or more. If the amount of the basic compound added is less than this, the polycondensation reaction will not be smoothly promoted.

Any basic compound or basic solvent can be used as long as it does not decompose the inorganic silazane that is the starting material. These include, for example, trialkylamines such as trimethylamine, dimethylethylamine, diethylmethylamine and triethylamine;
In addition to tertiary amines such as pyridine, picoline, dimethylaniline, pyrazine, pyrimidine, pyridazine and their derivatives, pyrrole, 3-pyrroline, pyrazole,
-pyrazoline, and mixtures thereof. Examples of non-basic solvents include 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 group ethers and alicyclic ethers can be used. Preferred solvents include halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, ethylidene chloride, trichloroethane, and tetrachloroethane;
Ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-dioxyethane,
Ethers such as dioxane, dimethyldioxane, tetrahydrofuran, and tetrahydropyran, pentane, hexane, isohexane, methylpentane, heptane, isohbutane, octane, isooctane, cyclopentane,
These include hydrocarbons such as methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, and ethylbenzene.

The polycondensation reaction of the present invention is carried out in the solvent as described above, but in this case, the concentration of the raw material inorganic silazane in the solvent is 0.
1% to 50% by weight, preferably 1% to 12% by weight. If the concentration of inorganic silazane is lower than this, the intermolecular polycondensation reaction will not proceed sufficiently, and if it is higher than this, the intermolecular polycondensation reaction will proceed too much and a gel will be produced. The reaction temperature is -78°C to 300°C, preferably -40°C to
The temperature is 200° C. At lower temperatures, the polycondensation reaction does not proceed sufficiently, and at higher temperatures, the polycondensation reaction proceeds too much and forms 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 necessary and normal pressure can be employed. Note that the reaction time depends on the type and concentration of the inorganic silazane as a starting material, the type of basic compound or basic solvent,
Although it varies depending on various conditions such as concentration and polycondensation reaction temperature, a range of 0.5 to 20 hours is sufficient for boat fishing.

The optimum conditions for the polycondensation reaction vary depending on the average molecular weight, molecular weight distribution, etc. of the inorganic silazane starting material.

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, a solvent solution containing an inorganic silazane high polymer, that is, a high molecular weight inorganic silazane, is obtained. Solvent content is 30% by weight in total solvent
The content is preferably 5% by weight or less. Basic compounds or basic solvents act as catalysts for the intermolecular polycondensation reaction of inorganic silazane polymers, so if their proportion to the total solvent is too large, gels may form during long-term storage at room temperature. do. Adjustment of this solution composition is carried out in step 2. For example, the inorganic silazane polymer solution obtained in the polycondensation reaction is evaporated to remove the basic compound or solvent contained therein, and then the non-basic (non-reactive) ) This can be done 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 one reaction solvent, the above-mentioned solution composition adjustment operation consisting of evaporation removal of the basic compound and addition of a non-basic solvent should be repeated. As the non-basic solvent for forming a stable solution of the inorganic silazane polymer in the present invention, aliphatic hydrocarbons and alicyclic carbonates as shown above can be used. Hydrogen, aromatic hydrocarbons, halogenated hydrocarbons, aliphatic ethers, alicyclic ethers, etc. can be used.

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

(1) In the general formula (1), I H The inorganic silazane high polymer of the present invention is a polymer produced by the polycondensation reaction of raw material inorganic silazane as described above, and has new crosslinks in the inorganic silazane molecules. It has a high molecular weight due to bonding.

That is, since the inorganic silazane polymer of the present invention is formed by crosslinking and polymerizing inorganic silazane having a number average molecular weight of 100 to 50,000 as a raw material as described above, its molecular weight is ,As a matter of course,
The molecular weight is higher than that of the raw material inorganic silazane. - For boat fishing, the inorganic silazane polymer targeted by the present invention has a number average molecular weight of 200 to 1,500 to 10,000, preferably 1,500 to 10,000.

The inorganic silazane polymer of the present invention has the above-mentioned characteristics in terms of the pentamolecular structure and is distinguished from the raw material inorganic silazane, but it also has many branched structures. There is one. Due to this branched structure, the inorganic silazane polymer of the present invention has a higher molecular weight than the raw material inorganic silazane, but rather provides improved solvent solubility. For example, 5eyfer
The inorganic silazane previously proposed by th et al.
-1 is an oily liquid with a proton ratio of about 3.3, but it solidifies by heating at about 200°C or leaving it at room temperature for 3 to 5 days. The inorganic silazane polymer has a molecular weight of 200 to soo, ooo, and the number of groups in one molecule is usually
The reason why the inorganic silazane high polymer of the present invention has more branched structure than the raw material inorganic silazane is that the inorganic silazane polymer of the present invention has more branched structure than the raw material inorganic silazane. In addition to the polycondensation reaction, it is thought that the following reactions occur, for example.

The branched structure of the inorganic silazane high polymer of the present invention is as follows.

For example, 'HNMR spectroscopy gives (
SiH, )/(SiHs) ((SiH2) :δ
1/2 of the area of 5L-H resonance in 4.8, (SiH
i) “1/3 of the 5i-H resonance area at δ4.4
] It can be evaluated by the ratio. In the case of raw material inorganic silazane, the (SiH,)/(SiHi) ratio is 5.0
~19.0, but in the case of the inorganic silazane high polymers of the present invention, the values are lowered from 265 to 8.4, respectively. If the SiH□/SiH3 ratio of the inorganic silazane high polymer is not within the above range, coagulation properties, shaping properties, etc. will be poor, and the intended purpose of the present invention will not be achieved.

The inorganic silazane polymer of the present invention has the above-mentioned molecular structural characteristics, and in terms of physical properties, it is soluble in organic solvents while having cross-linked bonds, and in particular, it can be obtained by removing the solvent from the solution. The obtained solid polymer exhibits a major feature of being re-soluble in a solvent. Conventional inorganic silazane has poor stability, and when the solvent is removed from its solution, it produces a resinous solid, which is insoluble in the solvent.
The inorganic silazane polymer of the present invention does not exhibit this tendency. Therefore, while conventional inorganic silazane is impossible or extremely difficult to handle as a solid polymer, the inorganic silazane high polymer of the present invention can be easily handled as a solid polymer.

Furthermore, the inorganic silazane polymer of the present invention has an elemental ratio of Si:
The preferred element ratios of the inorganic silazane high polymer of the present invention are: 59% by weight ff1% - 70% by weight, N: 20% by weight - 34% by weight, H: 5% by weight - 9% by weight. Si: 61% to 68% by weight, N: 25% to 33% by weight
Weight calculation: H: 5% by weight - 8% by weight 2, more preferable element ratios are Si: 64% by weight - 68% by weight, N: 27
% by weight - 33% by weight, H: 5% by weight - 7% by weight.

If the element ratio of the inorganic silazane high polymer does not satisfy the above range, it will be difficult to easily handle it as a solid polymer, making it impossible to achieve the intended purpose of the present invention.

In the present invention, in order to form a coating agent using the inorganic silazane high polymer, it is usually sufficient to dissolve the inorganic silazane high polymer in a solvent. Examples of solvents include hydrocarbon solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons, halogenated hydrocarbons such as halogenated methane, halogenated ethane, and halogenated benzene, aliphatic ethers, and alicyclic ethers. Ethers such as can be used. Preferred solvents include halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, ethylidene chloride, trichloroethane, and tetrachloroethane;
Ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-dioxyethane,
Ethers such as dioxane, dimethyldioxane, tetrahydrofuran, tetrahydrobilane, pentanehexane, isohexane, methylpentane, heptane, isohbutane, octane, isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, These include hydrocarbons such as ethylbenzene.

When using these solvents, two or more types of solvents may be mixed in order to adjust the solubility of the inorganic silazane polymer and the evaporation rate of the solvent.

The amount (proportion) of the solvent used is selected to improve workability depending on the coating method employed, and varies depending on the average molecular weight, molecular weight distribution, and structure of the inorganic silazane polymer, but the solvent content in the coating agent is approximately 90% by weight. It is possible to mix up to 50% by weight, preferably in the range of 10% to 50% by weight.

Further, a suitable filler may be added as necessary. Examples of fillers 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, it is also possible to add metal powders such as aluminum, zinc, copper, etc. If we look at examples of fillers in more detail,
Silica sand.

Silica-based products such as quartz, tubaculite, and diatomaceous earth: Synthetic amorphous silica: Kaolinite, mica, talc, wollastonite, asbestos, calcium silicate, aluminum silicate, and other silicates, glass powder, glass spheres, and hollow glass. Glass bodies such as spheres, glass flakes, and bubble glass bulbs: Non-oxide-based inorganic substances such as boron nitride, boron carbide, aluminum nitride, aluminum carbide, silicon nitride, silicon carbide, titanium boride, titanium nitride, and titanium carbide: calcium carbonate : Metal oxides such as zinc oxide, alumina, magnesia, titanium oxide, beryllium oxide, etc.: Barium sulfate, molybdenum disulfide, tungsten disulfide, carbon fluoride and other inorganic materials Nialuminum, bronze, lead, stainless steel,
Metal powders such as zinc: carbon bodies such as carbon black, coke, graphite, pyrolytic carbon, and hollow blade-bond balls.

These fillers are acicular (including whiskers), granular,
Those in various shapes such as scales can be used alone or in combination of two or more kinds. Further, it is desirable that the particle size of these fillers is smaller than the thickness of a film that can be coated at one time.

Further, the amount of the filler added is in the range of 0.05 parts by weight to 10 parts by weight, and a particularly preferable amount is in the range of 0.2 parts by weight 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 treated with a coupling agent, vapor deposition, plating, etc. before use.

Furthermore, the coating agent may contain various pigments, leveling agents, antifoaming agents, antistatic agents, ultraviolet absorbers, and PI.
(conditioner, dispersant, surface modifier, plasticizer, drying accelerator,
Anti-flow agents may be added.

The coating agent thus prepared is uniformly dissolved and decomposed to coat a substrate such as metal, ceramics, plastic, etc. As a coating means, conventional coating methods such as dipping, roll coating, bar coating, brush coating, spray coating, flow coating, etc. are used. Furthermore, if the substrate is surface treated by sanding, degreasing, various types of blasting, etc. before application, the adhesion performance of the coating composition will be improved. Coating in this way,
After thoroughly drying, heat and bake. By this baking, the inorganic silazane high polymer is crosslinked, condensed, and hardened to form a tough coating.

The above-mentioned firing conditions vary depending on the molecular weight and structure of the inorganic silazane polymer, but the firing is performed at a temperature in the range of 100°C to 1000°C with a gradual temperature increase rate of 0.5°C to 10°C for 7 minutes.

The preferred firing temperature is in the range of 200°C to 500°C.

The firing atmosphere may be air or an inert gas, but if it is a non-oxidizing atmosphere, the 5L-N bond can be formed.
Since a film of 5i-0 bonds is formed in an oxidizing or hydrolytic atmosphere, the atmosphere can be appropriately selected depending on the substrate.

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, etc. and ceramics, and also as an insulating film for multi-metal 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 organic solvents such as xylene.

Therefore, by adding various ceramic powders and an inorganic silazane high polymer to such a solvent and mixing them, it is possible to easily disperse them uniformly as a binder in the ceramic powder. Here, since the inorganic silazane high polymer also acts as a peptizer (dispersant), the present slurry becomes a homogeneous slurry suitable for granulation or slurry molding. Therefore, as a forming method,
Press molding methods such as a mold press method and a rubber press method, slurry molding methods 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, highly active Si and N react with the ceramic particles, and the inorganic silazane high polymer is used as a binder for sintering. It acts to form strong bonds between particles. Here, this bonding force is stronger as a preceramic polymer with a higher pyrolysis yield is used, and furthermore, a preceramic polymer that does not leave excess carbon that does not participate in bonding is stronger, so it is essentially an organic group. The inorganic silazane polymer, which has a composition of high purity Si3N after thermal decomposition, can be said to be a preceramic polymer suitable as a binder for sintering. Alternatively, since it fills the spaces between ceramic particles in the form of extremely small crystal grains of 100 Å or less, it also plays a role as a grain growth suppressant.

The above reaction starts at about 400°C and is completed at about 1500°C. Therefore, 5L3N4. Conventionally, inorganic sintered ceramics represented by non-oxides such as SiC,
High-temperature sintering of 1700°C or higher has been performed, but according to the present invention, a ceramic molded sintered body with excellent mechanical properties can be obtained at a temperature of about 1300 to 1500°C, despite having a relatively low density. It will be done.

In addition, the amount of the inorganic silazane high polymer added depends on the characteristics of the desired sintered body, such as strength, density, workability, etc.
It is possible to increase or decrease without limit. This is because, unlike conventional preceramic polymers, by controlling the degree of polymerization, the degree of melting can be reduced and 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 inorganic silazane high polymer are added to a solvent and mixed to create a slurry and then slurry molded, or from this slurry to a solvent. can be evaporated to create granulated powder, which can then be press-molded.

For example, in order to apply the press method, the solvent in the slurry may be evaporated using a spray dryer to form granulated powder. At this time, the inorganic polysilazane acts as a molding binder for granulation and is uniformly mixed into the ceramic powder as a sintered body binder (sintering aid). By press-molding the granulated powder obtained in this way, a molded article having a predetermined shape can be obtained. Also, according to the slurry molding method,
A molded body in which binder for molding and sintering is uniformly mixed can be obtained directly without using granulated powder.

In addition, in the present invention, a ceramic molded body (sintered body) is immersed in a solution in which an inorganic silazane high polymer is dissolved in a solvent.
It is also possible to densify a ceramic molded body (sintered body) by firing a ceramic molded body in which the molded body (sintered body) is impregnated with an inorganic silazane high polymer.

Examples of solvents include hydrocarbon solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons, halogenated hydrocarbons such as halogenated methane, halogenated ethane, and halogenated benzene, aliphatic ethers, and alicyclic ethers. Ethers such as can be used. Preferred solvents are methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride,
Halogenated hydrocarbons such as ethylidene chloride, trichloroethane, and tetrachloroethane, ethers such as ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-dioxyethane, dioxane, dimethyldioxane, tetrahydrofuran, and tetrahydropyran, pentane, hexane, and isohexane , methylpentane, heptane, isohbutane, octane, isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, ethylbenzene, and other hydrocarbons.

The obtained ceramic molded body is fired to turn the inorganic silazane polymer into a ceramic, thereby obtaining a ceramic molded sintered body. Firing conditions include heating and sintering in a temperature range of 600 to 2300° C. in a vacuum, in an atmosphere consisting of at least one selected from inert gas, reducing gas, and hydrocarbon gas.

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

Thus, according to the present invention, by selecting polysilazane as the preceramic polymer and selecting polysilazane having no organic group in the side chain, ceramic forming and sintering with excellent mechanical and chemical properties can be achieved by firing at a low temperature. You get a body.

〔effect〕

The inorganic silazane polymer of the present invention has the above-mentioned molecular structure and physical characteristics, and can be used in various fields. Next, the usage and production characteristics of the inorganic silazane high polymer of the present invention will be shown.

■ Inorganic silazane high polymers are soluble in organic solvents,
Since it can be converted into silicon nitride or silicon nitride-containing ceramics by firing, it can be converted into a high-performance ceramic molded body, that is, a high-temperature mechanical strength, heat resistance, corrosion resistance, oxidation resistance, and heat resistance [! Continuous fibers, films, and coatings with excellent properties can be easily obtained. Moreover, since the ceramic yield is high, it can also be used as a binder for sintering, an impregnating agent, etc.

■ Inorganic silazane high polymers do not contain impurities such as residual catalysts that promote decomposition, so they have improved stability and are easier to handle, and they also improve the purity of ceramics after high-temperature firing. improves.

■ Inorganic silazane high polymers have an increased crosslinked structure and molecular weight compared to the raw material inorganic silazane, resulting in improved coagulation properties.
It becomes possible to form the product quickly at room temperature.

■ Since a catalyst such as a transition metal is not used, there is no need for a separation process between the product and the catalyst.

■ Since no catalyst remains in the polymer, stability is improved and long-term storage is possible even after removal of the solvent and isolation.

■ It is low cost and safe because it does not use expensive and dangerous catalysts.

■ Due to its high molecular weight, evaporation loss during high-temperature firing is small, improving ceramic yield.

■ Since there are no impurities mixed in, the purity of ceramics after high-temperature firing is improved.

■ When spinning an inorganic silazane high polymer, continuous spinning is possible without adding a spinning aid.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Reference Example 1 A four-loop flask with an internal volume of 500 m and Q was equipped with a gas blowing pipe, a mechanical stirrer, and a dewar condenser. After replacing the inside of the reactor with deoxygenated dry nitrogen,
280 mQ of degassed dry pyridine was placed in a four-necked flask and cooled on ice. Next, 51.6g of dichlorosilane
When added, a white solid adduct (Si) I, C (12
・2C, H, N) were generated. The reaction mixture was ice-cooled, and while stirring, 30.0 g of purified ammonia was blown into the reaction mixture through a sodium hydroxide tube and an activated carbon tube.

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

The number average molecular weight of the obtained polymer was determined to be 1020 by GPC. In addition, when examining the IR (infrared absorption) spectrum of this polymer (solvent: dry 〇-xylene; concentration of inorganic silazane: 9.8 g/Q), it was found that Absorption; absorption based on SiH of 2170 (i = 3.14); SiH of 1020-820 and 5iNSi
It was confirmed that the absorption based on In addition, the 18NMR (proton nuclear magnetic resonance) spectrum (6
When examining 0MI (z, solvent CDCΩ3/reference material TMS), it was confirmed that all of them exhibited broad absorption. i.e. 64.8 and 4.4 (br, 5iH)
; Absorption of 1.5 (br, N) was confirmed.

Reference example 2 The reaction was carried out using the same apparatus as in Reference Example 1.

That is, 260 mA of degassed dry dichloromethane was placed in the four-loaf flask shown in Reference Example 1, and cooled on ice.

Next, 25.0 g of dichlorosilane was added. This solution was ice-cooled, and while stirring, 22.3 g of purified ammonia was blown into the solution as a mixed gas with nitrogen through a sodium hydroxide tube and an activated carbon tube. During the reaction, powder mist was generated in the gas flow path, so the gas flow path was occasionally tapped to prevent clogging.

The reaction mixture was treated in the same manner as in Reference Example 1 to obtain 4.9 g of viscous oily inorganic silazane. The number average molecular weight of the obtained polymer was 620 as measured by GPC.

Reference example 3 The reaction was carried out using the same apparatus as in Reference Example 1.

That is, 300 mm of degassed dry benzene was placed in the four-loaf flask shown in Reference Example 1 and 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 into the solution as a mixed gas with nitrogen through a sodium hydroxide tube and an activated carbon tube. During the reaction, powder mist was generated in the gas flow path, so the gas flow path was occasionally tapped to prevent clogging.

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

Example 1 100 mff of the inorganic silazane pyridine solution obtained in Reference Example 1 (concentration of inorganic silazane, 5.24% by weight) was placed in a pressure-resistant reaction vessel with an internal volume of 300+nQ, and heated at 150°C in a closed system in a nitrogen atmosphere for 30 minutes. The reaction was carried out with stirring for hours. During this time, a large amount of gas was generated. The pressure is 1 before and after the reaction.
．． O1cg/ci increased. After cooling to room temperature, add 200m Q of dry ethylbenzene, pressure 3-5n3-5n,
When the solvent was removed at a temperature of 50 to 70°C, 4.68 g of 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 2470 as measured by GPC. In addition, as a result of analysis of its IR spectrum (solvent: ethylbenzene), the wavenumber (country-'
) NH-based absorption of 3350 and 1175; 21
Absorption based on SiH of 70; SiH of 1020-820
It was confirmed that the absorption based on 5iNSi and 5iNSi was exhibited. Furthermore, the 18NMR spectrum (C
DCQ, , TMS) were analyzed and all showed a wide absorption, i.e. 64.8 (br, TMS).
SiH. ), δ4.4 (br, SiH,).

Absorption at δ1.5 (br, NH) was observed. (Si)
It)/(SIHa)=4.1.

Example 2 200 mR of the inorganic silazane pyridine solution obtained in Reference Example 1 (concentration of inorganic silazane, 6.18% by weight) was placed in a pressure-resistant reaction vessel with an internal volume of 300 a+Q, and a nitrogen atmosphere was added.
The reaction was carried out in a closed system at 120° C. for 3 hours with stirring. During this time, a large amount of gas was generated, which was determined to be hydrogen by gas chromatography (GC) measurement.

The pressure increase before and after the reaction was 2.0 kg/d.

After cooling to room temperature, dry. - When 400 mQ of xylene was added and the solvent was removed at a pressure of 3 to 5 mmHg and a temperature of 50 to 70°C, 10.9 g of white powder was obtained, and this powder was soluble in the organic solvent.

The number average molecular weight of the polymer powder was 1950 as measured by GPC.

The results of elemental analysis 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 for 1
The mixture was heated to 400° C. at a temperature increase rate of 3° C./min and fired for 3 hours to obtain a brown powder with a yield of 79.6% by weight.

Powder X-ray diffraction measurement of the obtained ceramic revealed that 2θ=20. . (101) diffraction line of α-3i3N4, α-3i, N4 (110) at 2θ=22.9'
) Diffraction lines.

20 = (200) diffraction line of α-3i3N4 at 26.4@, (201) diffraction line of α-3i3N4 at 2θ = 30.9'', (002) of α-8i3N4 at 2θ = 31.7@
Diffraction line, α-3i at 2θ = 34.5', (10
2) Diffraction line, α-3i at 2θ = 35.2°, N4 (
210) Diffraction line, (211) diffraction line of a-3iaN4 at 2θ = 38.8°, α-3L3N4 at 2θ = 39.4°
(112) diffraction line, α-3L3N at 2θ=40.1'
(300) diffraction line of 4, α-3L at 2θ=41.8”,
(202) diffraction line of N4, α-3 at 2θ=43.4°
i, (301) diffraction line of N4, 2θ=46.9” Ni a-3i, N, +7)) 220) Diffraction i, 2 B
= 48.2" (212) diffraction line of N4 at 2θ = 48.8°, (310) diffraction line of α-3L3N4 at 2θ = 48.8°, and (310) diffraction line of α-3L3N4 at 2θ = 23.3' Ni β-5i, N, ( 7)
(110) diffraction line, β-3i3N4 at 2θ=26.9°
(200) diffraction line.

2 B = 33.6' nip-3L3N4 ノ(101
) Diffraction line, β-3i, N, at 2θ=36°01 (
210) Diffraction line, β5iaN4('
) (201) Diffraction line, 2θ=49.9” L-3L
, N, (7) (310) diffraction line, S at 2θ=28.4'
i's (111) diffraction line, 2θ=47.3@Si's (2
20) Diffraction lines were observed, confirming that it was crystalline silicon nitride.

The elemental analysis results of this crystalline silicon nitride are (wt%) Si:
63.8. N:28.7. O:2.17. C:0
．． 36. H: 0.11.

Example 4 α-picoline solution of inorganic silazane obtained in Reference Example 1 (
120 mQ of inorganic silazane (concentration: 5.86% by weight) was placed in a pressure-resistant reaction vessel with an internal volume of 300 m 11, and the reaction was carried out at 120° C. for 3 hours with stirring in a closed system in 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 white powder of an inorganic silazane high polymer was obtained. This powder was soluble in organic solvents, and its number average molecular weight was 1850 as measured by GPC.

Example 5 A pyridine solution of the inorganic silazane obtained in Reference Example 2 (concentration of inorganic silazane, 7.25% by weight) was placed in a pressure-resistant reaction vessel with an internal volume of 300 m Q, and was placed in a nitrogen atmosphere.
The reaction was carried out in a closed system at 120°C with stirring for 5 hours. 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, 6.43 g of white powder of an inorganic silazane high polymer was obtained. This powder was soluble in organic solvents, and its number average molecular weight was 2030 when measured by GPC.

Example 6 100 mff of the inorganic silazane pyridine solution obtained in Reference Example 3 (concentration of inorganic silazane, 10.3% by weight) was placed in a pressure-resistant reaction vessel with an internal volume of 30,001 Q, and heated at 120°C in a closed system in a nitrogen atmosphere at 8°C. The reaction was carried out with stirring for hours. 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, a white powder of inorganic silazane high polymer was obtained. ．． 15g was obtained. This powder was soluble in organic solvents and had a number average molecular weight of 1880 by GPC.

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 Inorganic silazane high polymer powder produced by the method of Example 1 (
Ortho-xylene and silicon carbide (average particle diameter of about 10 microns) are added as a filler to a material with a number average molecular weight of 2470,
A solution of 45% by weight of inorganic silazane, 25% by weight of ortho-xylene and 30% by weight of silicon carbide was prepared.

This is the SS41 base (70 heavy m x 30IX 1 mn
It was applied to the surface of t) by spraying. After coating the substrate, the coating was dried by heating at 200° C. for 1 hour in a drying oven under an inert gas (nitrogen) atmosphere.The temperature increase rate was 3° C./min. As a result, a coating having a thickness of about 160 μm was obtained. The performance of the coating is shown in Table 1.

The testing method is as shown below.

b) Outside r/A: Check for cracks, color tone, and defects in the underlying coating film by visual observation.

Mouth) Pencil hardness: According to JIS K5400.

c) Adhesion (substrate peeling test): 1 m with a steel knife on the coating film.
Make 100 cuts in the base material that reach m square material,
After pasting cellophane tape (Tanezu Kagaku Kogyo) on top of it, the cellophane tape is strongly peeled off in an upward direction of 90°, and the evaluation is based on the number of squares remaining.

Example 9 Inorganic silazane high polymer 25% by weight, ortho-xylene 15
A solution of 60% by weight of silicon carbide and 0.5% by weight of auxiliary agent was prepared, and the method was the same as that of the example except that it was applied by brushing onto a 5O3304 substrate and baked at 00°C for 1 hour in a nitrogen gas atmosphere. When treated in the same manner, the results shown in Table 1 were obtained as a film.

Example 1 Inorganic silazane high polymer 90% gravity and ortho-xylene 1
A 0% by weight solution was prepared, coated on 5US304 by dipping, and treated in the same manner as in Example 8, except that it was baked in air at 400°C for 1 hour, resulting in a coating film shown in Table 1.
The results shown are obtained.

Example 11 A Si3N4 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 the inorganic polysilazane. The bulk density of the 0-piece sintered body was 2.
．． The sintered body had a bending strength of 75 g/ad and a transverse strength of IL 2 kg/m+a'', and a sintered body with higher density and higher strength than that in Example 1 was obtained.

Example 12 The 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 the inorganic polysilazane. The bulk density of the 0-wire sintered body was 2.75 g/a1,
The bending strength was 16.4 kg/am'', which exceeded the result of Example 2.

Claims (4)

[Claims] (1) The number average molecular weight is 200 to 500,000, and 1
The ratio of SiH_3 groups to SiH_2 groups in the molecule (SiH_2
group/SiH_3 group) is 2.5 to 8.4, and the element ratios are Si: 50 weight % to 70 weight %, N: 20 weight % to 34 weight %, H: 5 weight % to 9 weight %. An inorganic silazane high polymer. (2) The method for producing an inorganic silazane polymer according to claim (1), wherein the inorganic silazane is heated in a basic solvent or in a solvent containing a basic compound. (3) A coating agent containing the inorganic silazane high polymer according to claim (1) as an essential component. (4) A binder containing the inorganic silazane polymer according to claim (1) as an essential component.