JPH10182835A - Phenylsilyl group-crosslinked polysilazane and method for producing the same - Google Patents

Abstract

(57) [Problem] To provide a crosslinked polysilazane having a high molecular weight and excellent storage stability. SOLUTION: The following general formula (I): Having a number average molecular weight of 100 to 500 having a skeleton represented by
At least a part of the polysilazane main chain of the formula (00) has the following structural formula (2): [Wherein R ¹ , R ² and R ^{3 in the} above structural formula are as described in the specification], a phenylsilyl group-crosslinked polysilazane which is crosslinked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polysilazane crosslinked by a phenylsilyl group (hereinafter referred to as a phenylsilyl group-crosslinked polysilazane) and a method for producing the same. The phenylsilyl group-crosslinked polysilazane according to the present invention has a high molecular weight, excellent storage stability, and a high retention of organic components during ceramicization, and thus is particularly useful as a coating composition component for forming a ceramic film. .

[0002]

2. Description of the Related Art The usefulness of ceramic coatings as protective coatings is increasing. Specifically, by applying a silicone-based coating, a polytitanocarbosilane-based coating, a silazane-based preceramic polymer, a siloxazan-based preceramic polymer, or the like to the surface of a metal material or an inorganic material, high heat resistance and oxidation resistance are obtained. Inorganic coatings exhibiting properties, abrasion resistance, chemical resistance, substance barrier properties, etc. have been obtained. The present applicant has conventionally provided various materials as silazane-based preceramic polymers. According to these preceramic polymers, a coating composition dissolved in an appropriate solvent is prepared, and then simply coated and baked on the surface of a base material, resulting in dense and high-hardness heat resistance, oxidation resistance, and abrasion resistance. Thus, a coating having chemical resistance and high flatness can be obtained.

[0003] The present applicant also binds an organic component such as an alkyl group or a phenyl group to Si and / or N of the polysilazane main chain before ceramicization for the purpose of reducing the brittleness of the ceramic and introducing a carbon component. (See, for example, Japanese Patent Publication No. 4-4697).
No. 4). Further, by subjecting these preceramic polymers to low-temperature ceramic treatment, such a ceramic-based coating can be applied to a substrate having low heat resistance such as a plastic material.
Please refer to Japanese Patent Application Laid-Open No. 7-223867 by the present applicant as a representative published patent publication relating to ceramic-based coating using these polysilazanes.

[0004]

The polysilazane produced by the above-mentioned prior art has a limit in the molecular weight to be obtained, and a desired high viscosity may not be obtained as a coating composition in some cases. In order to increase the molecular weight of the polysilazane, water or oxygen is reacted with the polysilazane to form a siloxane cross-link using hydrogen bonded to silicon of the polysilazane, thereby forming a polysilazane cross-linked product having a higher molecular weight (polysiloxane). A method for obtaining the same is described in Japanese Patent Publication No. 6-18885 by the present applicant. High preceramic polymer molecular weight can be obtained according to this method, but also increases the viscosity of the coating composition, the polysiloxazanes is -NH ₂ at its molecular end, -OH, -SiH
Due to the inclusion of a group such as _3, there is a problem that the higher the molecular weight, the more likely it is to gel at room temperature, that is, the storage stability deteriorates.

Further, the organic component bonded to the polysilazane main chain for the purpose of reducing the brittleness of the ceramics or introducing the carbon component may be lost by heat during the formation of the ceramic, so that such an organic component is not stable. It is also desired to further improve heat resistance and heat resistance. Accordingly, the present invention provides a novel crosslinked polysilazane product having a higher molecular weight and superior storage stability than that obtained by a conventional method, and which can sufficiently retain an organic component even after ceramization, and a method for producing the same. is there.

[0006]

According to one aspect of the present invention, [1] mainly the following structural formula (1):

[0007]

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The number average molecular weight having a skeleton represented by
At least a part of the polysilazane main chain of 00 to 50,000 has the following structural formula (2):

[0009]

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[In the above structural formulas (1) and (2),
R ¹ , R ² and R ³ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group,
Or a group other than these groups, in which a group directly bonded to silicon is carbon, represents an alkylsilyl group, an alkylamino group, or an alkoxy group]. Polysilazane is provided.

According to another aspect of the present invention, there is provided a coating composition comprising the phenylsilyl group-crosslinked polysilazane described in [2] and [1] and a solvent. Further, according to another aspect of the present invention, [3] mainly the following general formula (1):

[0012]

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A number average molecular weight having a skeleton represented by
00 to 50,000 polysilazane, and the following structural formula (3):

[0014]

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[In the above structural formulas (1) and (3),
R ¹ , R ² and R ³ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group,
Or a group in which, other than these groups, a group directly connected to silicon is carbon, an alkylsilyl group, an alkylamino group, or an alkoxy group]. A method for producing a phenylsilyl group-crosslinked polysilazane, characterized by reacting in the presence of

Hereinafter, preferred embodiments of the present invention will be listed. [4] polystyrene reduced number average molecular weight of 500 to 10
The phenylsilyl-crosslinked polysilazane according to [1], which has a molecular weight of 000. [5] The phenylsilyl-crosslinked polysilazane according to [1] or [4], wherein the crosslinking index is 1.01 to 5.0.

[6] The phenylsilyl-crosslinked polysilazane has a polystyrene reduced number average molecular weight of 500 to 100,000.
The coating composition according to [2], which is 0. [7] The coating composition according to [2] or [6], wherein the phenylsilyl-crosslinked polysilazane has a crosslinking index of 1.01 to 5.0. [8] The coating composition according to [2], [6] or [7], further comprising an oxidation accelerating catalyst.

[0018]

[9] The basic organic compound is triethylamine, diethylamine, butylamine, dibutylamine,
The method according to [3], which is tributylamine, pyridine, 1,8-diazabicyclo [5.4.0] -7-undecene or 1,5-diazabicyclo [4.3.0] -5-nonene.

The phenylsilyl group-crosslinked polysilazane according to the present invention is prepared by reacting polysilazane with 1,4-bis (hydroxysilyl) benzene in the presence of a basic compound to obtain 1,4-bis (hydroxysilyl) benzene. Can be almost completely reacted with polysilazane, and the resulting phenylsilyl group-crosslinked polysilazane does not substantially contain OH groups in the molecular chain. For this reason, the obtained phenylsilyl group-crosslinked polysilazane does not further increase in molecular weight (gelation) with the lapse of time due to the remaining OH group, and a similar crosslinked polysilazane or polysiloxy compound synthesized without the presence of a basic compound. Higher storage stability than Southern. Further, the organic component (phenyl group) contained in the cross-linking portion has Si at the first and fourth positions, respectively.
Because it is bonded to the polysilazane main chain through the -O group,
The stability and heat resistance of the organic component are higher than those of the conventional polysilazane containing an organic component directly bonded to the main chain of polysilazane, and the organic component is sufficiently retained even after the phenylsilyl group-crosslinked polysilazane is ceramicized. Is done.

Hereinafter, the present invention will be described in detail. The polysilazane used in the present invention may be any polysilazane having at least a Si-H bond in the molecule, and may be used not only as a polysilazane alone but also as a copolymer of polysilazane and another polymer or a mixture of polysilazane and another compound. it can. The polysilazane to be used includes those having a chain, cyclic or crosslinked structure, and those having a plurality of these structures in the molecule at the same time, and these can be used alone or in a mixture.

The following are typical examples of the polysilazane to be used, but are not limited thereto. The compound having a hydrogen atom at R ¹ and R ² in the general formula (1) is perhydropolysilazane, and its production method is described in, for example, JP-A-60-145903, D.C. Seefe
Rth et al. Communication of Am. C
er. Soc. , C-13, January 198
3. Has been reported to. What is obtained by these methods is a mixture of polymers having various structures, but basically contains a chain portion and a cyclic portion in the molecule,

[0022]

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Can be represented by the following chemical formula. An example of the structure of perhydropolysilazane is as follows.

[0024]

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A method for producing a polysilazane having a hydrogen atom for R ¹ and a methyl group for R ² in the general formula (1) is described in D. Seey
Ferth et al., Polym. Prepr. Am. Che
m. Soc. , Div. Polym. Chem,. 2
5 , 10 (1984). The polysilazane obtained by this method has a repeating unit of-(SiH
A chain polymer and a cyclic polymer of ₂ NCH ₃ )-,
None have a crosslinked structure.

A method for producing a polyorgano (hydro) silazane having a hydrogen atom for R ² and an organic group for R ¹ in the general formula (1) is described in D. Seeyferth et al., Polym. Prepr.
Am. Chem. Soc. Div. Polym. Che
m,. 25, 10 (1984), JP-A-61-8923.
No. 0 reports. The polysilazane obtained by these methods, - (R ² SiHNH) - as a repeating unit, and which mainly polymerization degree having a cyclic structure 3~5 (R ³ SiHNH) _x [(R ² SiH) _1.5
N] _1-x (0.4 <X <1) Some molecules have both a chain structure and a cyclic structure in the molecule represented by the chemical formula.

In the general formula (1), the polysilazane having an organic group at R ¹ and R ² has a cyclic structure mainly having a degree of polymerization of 3 to 5, using-(R ¹ HSiNR ² )-as a repeating unit. . Next, typical examples of the polysilazane other than the general formula (1) will be given. Some polyorgano (hydro) silazanes include D.I. Seeferth et al Communi
site of Am. Cer. Soc. , C-1
32, July 1984. Some have a crosslinked structure in the molecule as reported. An example is as follows.

[0028]

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A polysilazane (R ¹ Si (NH) _x , or R ¹ ) having a crosslinked structure obtained by ammonia decomposition of R ¹ SiX ₃ (X: halogen) as reported in JP-A-49-69717. Six ₃ and R ² ₂
Polysilazane having the following structure obtained by co-ammonium decomposition of SiX ₂ can also be used as a starting material.

[0030]

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The polysilazane used has a main skeleton composed of the unit represented by the general formula (1) as described above. However, the unit represented by the general formula (1) may be cyclized as is apparent from the above. In such a case, the cyclic portion serves as a terminal group, and when such cyclization is not performed, the terminal of the main skeleton can be the same group as R ¹ and R ² or hydrogen.

The polysilazane used in the present invention is preferably a polysilazane having a unit represented by the above general formula (1) in the main skeleton or a metal alkoxide, a silicon alkoxide, an alcohol, a metal carboxylate, or acetylacetate. It is modified by adding a nato complex or the like. When the polysilazane thus modified is used as a starting material, the obtained phenylsilyl group-crosslinked polysilazane can be made into a ceramic at a lower temperature. Hereinafter, such a modification treatment is referred to as a low-temperature ceramicization treatment.

As a specific example of such a low temperature ceramicized polysilazane, Japanese Patent Application Laid-Open No.
Silicon alkoxide-added polysilazane described in JP-A-238827. The modified polysilazane is represented by the following general formula (II): Si (OR ⁴ ) ₄ (II) wherein R ⁴ may be the same or different; A hydrogen atom, an alkyl group or an aryl group having 1 to 20 carbon atoms, wherein at least one R ⁴ is an alkyl group or an aryl group described above). Alkoxide-derived silicon /
A silicon alkoxide-added polysilazane having an atomic ratio of silicon derived from polysilazane in the range of 0.001 to 3 and a number average molecular weight of about 200 to 500,000. The preparation of polysilazane with silicon alkoxide is described in JP-A-5-2388.
See No. 27 publication.

As another specific example of the polysilazane which has been subjected to low-temperature ceramic treatment, Japanese Patent Application Laid-Open No. 6-1228 by the present applicant has been disclosed.
No. 52, glycidol-added polysilazane. The modified polysilazane is obtained by reacting the polysilazane represented by the general formula (1) with glycidol, the weight ratio of glycidol / polysilazane is in the range of 0.001 to 2, and the number average molecular weight is about 200.
~ 500,000 glycidol-added polysilazanes. For the preparation of glycidol-added polysilazane, see the above-mentioned JP-A-6-122852.

As another specific example of the low temperature ceramicized polysilazane, JP-A-6-240 by the present applicant
No. 208, alcohol-added polysilazane. The modified polysilazane is obtained by reacting the polysilazane represented by the general formula (1) with an alcohol, the weight ratio of alcohol / polysilazane is in the range of 0.001 to 2, and the number average molecular weight is about 100 to 100.
500,000 alcohol-added polysilazanes. The preparation of the alcohol-added polysilazane is described in
See U.S. Pat.

As another specific example of low temperature ceramicized polysilazane, JP-A-6-2 by the present applicant
And the metal carboxylate-added polysilazane described in JP-A-99118. The modified polysilazane is a polysilazane represented by the general formula (1) and at least one metal selected from the group consisting of nickel, titanium, platinum, rhodium, cobalt, iron, ruthenium, osmium, palladium, iridium, and aluminum. Is a metal carboxylate-added polysilazane having a metal carboxylate / polysilazane weight ratio in the range of 0.000001 to 2 and a number average molecular weight of about 200 to 500,000 obtained by reacting a metal carboxylate containing . The metal carboxylate is represented by the formula (RCOO) _n M wherein R represents 1 to 2 carbon atoms.
Two aliphatic groups or alicyclic groups, M represents at least one metal selected from the above metal group, and n is a valence of the metal M]. The metal carboxylate may be an anhydride or a hydrate. For the preparation of the polysilazane to which the metal carboxylate is added, see the above-mentioned JP-A-6-299118.

As still another specific example of the low temperature ceramicized polysilazane, Japanese Patent Application Laid-Open No.
Acetylacetonate complex-added polysilazane described in JP-A-306329. This modified polysilazane has a weight ratio of acetylacetonato complex / polysilazane obtained by reacting polysilazane represented by the above general formula (1) with an acetylacetonate complex containing nickel, platinum, palladium or aluminum as a metal. An acetylacetonato complex-added polysilazane having a number average molecular weight of about 200,000 to 500,000 in the range of 0.000001 to 2 The metal-containing acetylacetonate complex is a complex in which an anion acac ⁻ generated by acid dissociation from acetylacetone (2,4-pentadione) is coordinated to a metal atom, and generally has a formula (CH ₃ COCHCOCH).
₃ ) It is represented by _n M [wherein M represents an n-valent metal].
For the preparation of acetylacetonato complex-added polysilazane, see the above-mentioned JP-A-6-306329.

As another specific example of polysilazane which has been subjected to low-temperature ceramic treatment, Japanese Patent Application Laid-Open No.
No. 96986 discloses polysilazane with added metal fine particles. This modified polysilazane is a modified polysilazane obtained by adding fine particles of a metal such as Au, Ag, Pd, and Ni to a coating solution containing polysilazane represented by the general formula (1) as a main component. The preferred metal is Ag. The particle diameter of the metal fine particles is preferably smaller than 0.5 μm, more preferably 0.1 μm or less, and further preferably smaller than 0.05 μm. For the preparation of the polysilazane to which metal fine particles are added, refer to the above-mentioned Japanese Patent Application Laid-Open No. 7-19698. Of these polysilazanes subjected to low-temperature ceramic treatment, particularly preferred are those described in JP-A-6-29911.
No. 8, the metal carboxylate-added polysilazane is described, and in particular, the metal (M) whose palladium (Pd) is more preferable. The phenylsilyl group-crosslinked polysilazane can be similarly ceramicized at a low temperature by applying the low-temperature ceramicization treatment to the phenylsilyl group-crosslinked polysilazane obtained from the unmodified polysilazane according to the present invention.

The phenylsilyl group-crosslinked polysilazane of the present invention is obtained by converting the above polysilazane or a modified product thereof into 1,4-bis (hydroxysilyl) represented by the following structural formula (3) in the presence of a basic organic compound. ) Obtained by reacting with benzene.

[0040]

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In the above formula, R ³ is each independently a hydrogen atom,
An alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group other than these groups in which a group directly connected to silicon is carbon, an alkylsilyl group, an alkylamino group, or an alkoxy group. R ³ is preferably a methyl group, an ethyl group or a phenyl group. When 1,4-bis (hydroxysilyl) benzene is reacted in the presence of a basic organic compound, one of the OH groups reacts with a Si—H bond of a molecule having polysilazane or a modified product thereof to form Si— An O bond is formed and the other OH group reacts with the Si-H bond of another molecule of polysilazane or a modification thereof to form Si-O
By forming a bond, a crosslinked portion is formed between molecules of polysilazane or a modified product thereof.

These 1,4-bis (hydroxysilyl) benzenes can be used in combination of two or more. Further, as 1,4-bis (hydroxysilyl) benzene, a compound capable of being hydrolyzed in situ and reacting with polysilazane as described above may be used.
Specifically, an esterified product of 1,4-bis (hydroxysilyl) benzene, for example, an acetate, a propionate, or the like may be used. The phenylsilyl group-crosslinked polysilazane according to the present invention has a crosslinked portion represented by the following structural formula (2) between polysilazane molecules.

[0043]

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In the above formula, R ¹ , R ² and R ³ are each independently a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group other than these groups which is directly bonded to silicon. Represents an alkyl group, an alkylsilyl group, an alkylamino group, or an alkoxy group. The crosslinking index of the phenylsilyl group-bridged polysilazane of the present invention, that is, the number of crosslinking points per molecule of polysilazane, depends on the intended purpose.
Also, it depends on the molecular weight of the starting polysilazane. For example, if the desired molecular weight after crosslinking is constant, the lower the polysilazane molecular weight of the starting material, the higher the crosslinking index needs to be. However, as a general rule, if the cross-linking index is set too high, the polymer becomes three-dimensional, which is not desirable as a component of the coating composition. Therefore, the crosslinking index of the phenylsilyl group-crosslinked polysilazane suitable as a component of the coating composition of the present invention is in the range of 1.01 to 5.0, preferably 1.01 to 1.5.

Further, the flexibility of the ceramic coating derived from phenylsilyl group-crosslinked polysilazane can be controlled by adjusting the type of 1,4-bis (hydroxysilyl) benzene and the amount introduced by crosslinking. That is, in general, when it is desired to increase the hardness of the ceramic coating, a group having a small number of hydrogen atoms or carbon atoms (for example, a methyl group) is selected as R ³ , and when it is desired to increase the flexibility of the ceramic coating, R ³ is selected.
Group having a large number of carbon atoms as ³ (for example, phenyl group)
May be selected, and a person skilled in the art can appropriately perform the selection as needed.

The phenylsilyl group-crosslinked polysilazane of the present invention can be obtained by a reaction in the presence of a basic organic compound. As the basic organic compound used in the present invention, primary, secondary and tertiary amines such as diethylamine, triethylamine, propylamine, dipropylamine,
Tripropylamine, butylamine, dibutylamine,
Tributylamine, pentylamine, dipentylamine, tripentylamine, hexylamine, dihexylamine, trihexylamine, heptylamine, diheptylamine, triheptylamine, octylamine, dioctylamine, trioctylamine, nonylamine,
Dinonylamine, decylamine, dodecylamine, phenylamine and diphenylamine, pyridines such as pyridine, picoline, lutidine, pyrimidine and pyridazine, and organic strongly basic compounds such as 1,8-diazabicyclo [5.4.0] -7-undecene (DBU)
And 1,5-diazabicyclo [4.3.0] -5-nonene (DBN). By performing the reaction in the presence of such a basic organic compound, OH groups do not remain in the molecular chain of the resulting phenylsilyl group-crosslinked polysilazane. Particularly preferred basic organic compounds are triethylamine, diethylamine, butylamine, dibutylamine, tributylamine, pyridine, DBU and DBN.

The synthesis reaction of the phenylsilyl-group-crosslinked polysilazane according to the present invention is generally carried out by preparing a solution in which the above-mentioned polysilazane is dissolved in an appropriate solvent, if necessary, and adding the above-mentioned basic organic compound thereto. The solution is prepared by adding 1,4-bis (hydroxysilyl) benzene as it is or by dissolving the solution in an appropriate solvent. Further, a solution prepared by dissolving the above 1,4-bis (hydroxysilyl) benzene as it is or in an appropriate solvent is prepared, and the above polysilazane is added to a solution prepared by adding the above basic organic compound thereto. If necessary, the reaction can be carried out by adding a solution dissolved in an appropriate solvent. When dissolving 1,4-bis (hydroxysilyl) benzene, it is preferable to use the above-mentioned basic organic compound as a solvent.

When polysilazane is dissolved in a solvent, the solvent is preferably a solvent for the finally obtained phenylsilyl group-crosslinked polysilazane, and is preferably an aromatic compound such as benzene, toluene, xylene, ethylbenzene, diethylbenzene and trimethyl. Benzene and triethylbenzene, cyclohexane, cyclohexene,
Decahydronaphthalene, dipentene, saturated hydrocarbon compounds such as n-pentane, i-pentane, n-hexane, i-hexane, n-heptane, i-heptane, n-
Octane, i-octane, n-nonane, i-nonane, n
-Decane and i-decane, ethylcyclohexane, methylcyclohexane, p-menthane, ethers such as dipropyl ether, dibutyl ether and dipentyl ether, and ketones such as methyl isobutyl ketone (MIBK). Phenylsilyl group-crosslinked polysilazane synthesized in such a solvent,
It can be used as it is as a coating composition.

In the synthesis reaction of the phenylsilyl group-crosslinked polysilazane according to the present invention, 0.01 to 90% by weight, preferably 1 to 10% by weight, of polysilazane is added to 99.9 to 10% by weight.
% By weight, preferably 99 to 90% by weight of a basic organic compound, and 0.01 to 200% by weight of polysilazane;
Preferably, it is combined with 0.1 to 10% of 1,4-bis (hydroxysilyl) benzene. This synthesis reaction,
The reaction is carried out at any temperature within the range from the freezing point to the boiling point of the solvent used, but is usually carried out at 0 to 100 ° C. This reaction proceeds even at room temperature.

The reaction pressure in the synthesis reaction of the phenylsilyl group-crosslinked polysilazane according to the present invention is not particularly limited, and normal pressure is generally sufficient. 0 to 9.8 × 10
^{The range of 5} Pa (0 to 10 kg / cm ² G) is preferable. The reaction time is not particularly limited, but is generally 1 to 120.
Perform a minute reaction. By increasing the reaction time, the molecular weight of the phenylsilyl group-crosslinked polysilazane obtained can be increased. The reaction atmosphere is not particularly limited, and may be an ambient atmosphere. After completion of the reaction, if necessary, the basic organic compound is distilled off using, for example, a rotary evaporator to obtain a phenylsilyl group-crosslinked polysilazane dissolved in the solvent used.

The phenylsilyl group-crosslinked polysilazane thus obtained has a main chain substantially consisting of Si—N bonds, and has a number average molecular weight in terms of polystyrene of 500 to 100,000, preferably 500, as determined by gel permeation chromatography. ~ 10,000, more preferably 500 ~ 5
000, a crosslinking index of 1.01 to 5.0, preferably 1.01 to 1.5, a nitrogen content of 10 to 40% by weight, preferably 15 to 35% by weight, and an oxygen content. Rate is 0.01 to 50% by weight, preferably 1 to 20% by weight. According to the present invention, the limiting viscosity in xylene at 20 ° C is 1.0 to 100 cP (0.001 to 0.
1 Pa · s), preferably 1.2 to 50 cP (0.00
A phenylsilyl group-crosslinked polysilazane having a pressure of 12 to 0.05 Pa · s) is obtained. Since the phenylsilyl group-crosslinked polysilazane according to the present invention is substantially free of free OH groups, there is little or no increase in molecular weight due to crosslinking during the storage period.

The phenylsilyl group-crosslinked polysilazane or a modified product thereof according to the present invention is applied to various base materials such as metal, glass, silicon substrate and plastic, and is converted into silica to obtain, for example, a semiconductor, a liquid crystal or the like. Insulating flattening film, antioxidant film on metal surface, oxygen, water vapor, N
A ceramic coating useful as a barrier film such as a or a protective film for a flexible substrate such as plastic can be obtained.
According to another aspect of the present invention, there is provided a coating composition in which such a phenylsilyl group-crosslinked polysilazane or a modified product thereof is dissolved in a solvent. Suitable solvents are as described above. The solvent may be one of those listed above, or may be dissolved in two or more solvents having different boiling points in order to adjust the solubility of the phenylsilyl group-crosslinked polysilazane and the evaporation rate of the solvent.

The amount (proportion) of the solvent used is selected so as to improve the workability by the coating method employed, and varies depending on the average molecular weight, molecular weight distribution and structure of the phenylsilyl group-crosslinked polysilazane used.
Can be mixed freely. Preferably, the phenylsilyl group-crosslinked polysilazane content can be mixed in the range of 0.01 to 70% by weight. In the coating composition of the present invention, an appropriate filler and / or extender can be added as needed. Examples of fillers include silica,
Examples include fine powders of oxide-based inorganic substances such as 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.

These fillers can be used alone or in various shapes such as needles (including whiskers), granules, and scales.
A mixture of more than one species can be used. Further, it is desirable that the size of the particles of these fillers is smaller than the film thickness that can be applied at one time. Further, the addition amount of the filler is in the range of 0.01 to 100 parts by weight based on 1 part by weight of the phenylsilyl group-crosslinked polysilazane, and the particularly preferable addition amount is in the range of 0.1 to 10 parts by weight. . The coating composition may contain various pigments, leveling agents, defoamers, antistatic agents, ultraviolet absorbers (including zinc oxide, titanium oxide, etc.), pH adjusters, dispersants, and surface modifiers as required. , A plasticizer, a drying accelerator and a flow stopper.

After repeatedly applying the above-mentioned phenylsilyl group-crosslinked polysilazane-containing coating composition to a substrate once or twice or more, it is fired and exposed to a steam atmosphere, or immersed in distilled water containing a catalyst, or By performing both, a ceramic coating film can be formed. The method of application is usually applied to plastic materials, i.e. dipping, roll coating, bar coating,
Brush coating, spray coating, flow coating and the like are used.
A particularly preferred application method is the gravure coating method.

The conditions for firing are different depending on the phenylsilyl group-crosslinked polysilazane or the coating composition to be used, and can be selected depending on the substrate or product to be coated. Low temperature ceramicized phenylsilyl group-crosslinked polysilazane can be ceramicized at a lower temperature than phenylsilyl group-crosslinked polysilazane containing no additives, even without using a low-temperature forming method, and even when ordinary firing is performed. . A low-temperature ceramic coating composition (especially a metal carboxylate adduct of a phenylsilyl group-crosslinked polysilazane, an acetylacetonate complex adduct, and a metal fine particle adduct) is used. The conditions are in the range of 500-1000C. Preferred firing temperatures are in the range of 250-400C, more preferably 250-350C.

The firing atmosphere may be any of oxygen, air, or an inert gas, but air is more preferable. Oxidation of the low-temperature ceramic composition, or hydrolysis by water vapor coexisting in the air, proceeds by firing in air, and the tertiary reaction mainly composed of Si—O bonds or Si—N bonds at the low firing temperature as described above. It is possible to form a tough coating having an original structure and remaining the organic component of the crosslinked portion. Furthermore, depending on the type of the low-temperature ceramic material composition to be coated, firing at 50 ° C. or higher is not performed at all, and the coated film after application is maintained at a temperature lower than 50 ° C. for a long time to improve the properties of the coated film. It is possible to do. In this case, the holding atmosphere is preferably in air, and more preferably in humid air having an increased water vapor pressure. The holding time is not particularly limited, but it is practically appropriate that the holding time is 10 minutes or more and 30 days or less. Further, the holding temperature is not particularly limited, but a temperature of 0 ° C. or more and less than 50 ° C. is practically appropriate. Although it is naturally effective to maintain the temperature at 50 ° C. or higher, the heating operation at 50 ° C. or higher is defined as “firing” in the text. Oxidation of the reaction product of the metal carboxylate and the crosslinked polysilazane or hydrolysis by water vapor coexisting in the air proceeds by the holding in the air, and the conversion to ceramics is completed, and the Si—O bond or Si −
It is possible to form a tough coating film having a three-dimensional structure mainly composed of N bonds and remaining the organic components in the crosslinked portions. According to the above method, various problems caused by a high firing temperature can be significantly reduced, and in some cases, conversion to ceramics at around room temperature becomes possible.

When the low-temperature forming method is employed, the rate of temperature rise is not particularly limited, but is preferably 0.5 to 5 ° C./min. The preferable baking temperature is from room temperature to 250 ° C., but when applying to a plastic material or the like, heat treatment is performed at a temperature that does not damage the plastic material, preferably 150 ° C. or less. Generally, when the heat treatment is performed at 150 ° C. or more,
The plastic material is damaged, for example, the plastic material is deformed or its strength is deteriorated. However, in the case of a plastic material having high heat resistance such as polyimide, processing at a higher temperature is possible.
A person skilled in the art can appropriately set according to the type of the plastic material. The firing atmosphere may be any of oxygen, air, or an inert gas, but air is more preferable. In the heat treatment at the above temperature, Si—O, S
Those having i-N, Si-H, and N-H bonds are formed. It is still incompletely converted to ceramics. This can be converted to ceramics by one or both of the following two methods.

Heat treatment in a steam atmosphere. The pressure is not particularly limited, but is 1 to 3 atm.
Really appropriate. Room temperature is effective above room temperature
Temperature to 150 ° C. is preferred. The relative humidity is not particularly limited
Is preferably 10% RH to 100% RH. Especially the heat treatment time
Although not limited, 10 minutes to 30 days are practically suitable.
That's right. Phenyl by heat treatment in a steam atmosphere
Silyl group crosslinked polysilazane or phenylsilyl group crosslinked
Oxidation of the modified product of polysilazane proceeds, as described above.
Three-dimensional structure mainly composed of Si-O bonds at very low firing temperature
Tough ceramics with organic components remaining
In this way, a ceramic coating can be formed. This SiO _Twosystem
The membrane is derived from phenylsilyl group-crosslinked polysilazane.
Nitrogen in an atomic percentage of 0.01 to 5%. This
If the elemental content is more than 5%, the film becomes insufficiently ceramic.
The desired effect, for example, abrasion resistance and gas barrier properties
Can not be obtained. On the other hand, if the nitrogen content is less than 0.01%
It is difficult to get rid of it.

Immerse in distilled water containing the catalyst. The catalyst is preferably an acid or a base, and the type thereof is not particularly limited. For example, triethylamine, diethylamine, monoethanolamine, diethanolamine, triethanolamine, n-exylamine, and n
-Butylamine, di-n-butylamine, tri-n-butylamine, guanidine, piguanine, imidazole,
Amines such as 1,8-diazabicyclo- [5,4,0] -7-undecene and 1,4-diazabicyclo- [2,2,2] -octane; sodium hydroxide, potassium hydroxide, lithium hydroxide, Alkalis such as pyridine and aqueous ammonia; inorganic acids such as phosphoric acid; lower monocarboxylic acids such as glacial acetic acid, acetic anhydride, propionic acid and propionic anhydride, or anhydrides thereof, oxalic acid, fumaric acid, maleic acid, Lower dicarboxylic acids such as succinic acid or anhydrides thereof, and organic acids such as trichloroacetic acid; perchloric acid, hydrochloric acid, nitric acid, sulfuric acid, sulfonic acid, paratoluenesulfonic acid, boron trifluoride, and complexes thereof with an electric donor , Etc .; SnCl
₄ , ZnCl ₂ , FeCl ₃ , AlCl ₃ , SbC
Lewis acids such as l ₃ and TiCl ₄ and their complexes can be used. The preferred catalyst is hydrochloric acid. The content of the catalyst is 0.01 to 50% by weight, preferably 1 to 50% by weight.
10 wt%. The holding temperature is effective from room temperature to the boiling point. The holding time is not particularly limited, but 10 minutes to 30 days is practically appropriate.

By immersion in distilled water containing a catalyst, oxidation of the phenylsilyl group-crosslinked polysilazane or a modified product of the phenylsilyl group-crosslinked polysilazane or hydrolysis with water is further accelerated by the presence of the catalyst. At a very low firing temperature, it is possible to form a tough ceramic, particularly a ceramic coating, having a three-dimensional structure mainly composed of Si-O bonds and remaining organic components. This S
Since the iO ₂ -based film is derived from phenylsilyl group-crosslinked polysilazane, it similarly contains about 0.01 to 5% of nitrogen in atomic percentage.

As another method of low-temperature ceramicization, there is a method in which palladium (Pd) is contained as an oxidation-promoting catalyst in a coating composition containing a phenylsilyl group-crosslinked polysilazane or a modified product thereof as described above. Specifically, Pd
^When a phenylsilyl group-crosslinked polysilazane containing ²⁺ ions is brought into contact with water vapor at a low temperature, silica is obtained. Si
Phenylsilyl group-crosslinked polysilazane having -H is Pd
^It is converted into ceramics mainly composed of silica at a low temperature in a system containing ²⁺ ions and water as essential components.

The supply amount of Pd ²⁺ ions was determined by the amount of silica (SiO 2
₂ ) In order to obtain ceramics having a composition close to the composition, it is preferable that the total amount of Si-H groups and Si-N groups of the phenylsilyl group-crosslinked polysilazane be equal to or more than the same mole. However, C in the reaction system
When a Pd ⁰ (zero-valent palladium) oxidation catalyst such as uCl ₂ is added, or when an operation such as electrochemical oxidation of Pd ⁰ is performed at the same time, the amount of Pd ²⁺ ions may be smaller than the above. An equivalent effect can be obtained. But,
The Pd ²⁺ ion is not limited to the above-mentioned preferable supply amount since a small amount of Pd ²⁺ ion can provide a certain effect. Therefore, in the case where the above operation is not performed, generally 1/100 mol or more, preferably 1/10 mol or more with respect to the total number of moles of Si—H groups and Si—N groups of the phenylsilyl group-crosslinked polysilazane, More preferably, 1 mol or more, and practically, 1/10 mol or more of Pd ²⁺ is supplied.

When the added amount of Pd is 1/10 mol,
For convenience, the phenylsilyl group-crosslinked polysilazane Si
When the molar amount of (silicon) is 0.2 times, the added weight of Pd is obtained. The water can be supplied by immersing the phenylsilyl group-crosslinked polysilazane in water, atomizing water and spraying the phenylsilyl group-crosslinked polysilazane, or exposing the phenylsilyl group-crosslinked polysilazane to water vapor. The amount of water supplied is preferably at least equimolar to the sum of the Si—H groups and Si—N groups of the phenylsilyl group-crosslinked polysilazane in order to obtain ceramics having a composition close to silica (SiO ₂ ). Usually a large excess of water is used.

The reaction conditions for the ceramization of the phenylsilyl group-crosslinked polysilazane include reaction temperature, reaction pressure,
The reaction atmosphere is not particularly limited. However, the reaction is heated as necessary, but the reaction proceeds sufficiently at a low temperature of 100 ° C. or less. For example, 80 ° C. or less, and even 4
It is possible even at 0 ° C. or less. As another method of low-temperature ceramicization, there is a method in which an amine compound and / or an acid compound is contained as an oxidation-promoting catalyst in a coating composition containing a phenylsilyl group-crosslinked polysilazane or a modified product thereof as described above. The amine compound used here includes, for example, an amine compound represented by the following general formula (III), pyridines, DBU, DBN, and the like, and an acid compound includes an organic acid and an inorganic acid.

Representative examples of the amine compound as the oxidation-promoting catalyst include a compound represented by the following general formula (III). R ⁴ R ⁵ R ⁶ N (III) In the formula, R ^{4 to} R ⁶ each represent a hydrogen atom, an alkyl group,
Represents an alkenyl group, a cycloalkyl group, an aryl group, an alkylsilyl group, an alkylamino group or an alkoxy group. Specific examples include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, pentylamine, dipentylamine,
Examples include tripentylamine, hexylamine, dihexylamine, trihexylamine, heptylamine, diheptylamine, triheptylamine, octylamine, dioctylamine, trioctylamine, phenylamine, diphenylamine, triphenylamine, and the like. In addition, the hydrocarbon chain contained in these amine compounds may be linear or branched. Particularly preferred amine compounds are triethylamine, tripentylamine, tributylamine, trihexylamine, triheptylamine and trioctylamine.

Specific examples of pyridines include pyridine, α
-Picoline, β-picoline, γ-picoline, piperidine, lutidine, pyrimidine, pyridazine and the like. Furthermore, DBU (1,8-diazabicyclo [5.
4.0] -7-undecene), DBN (1,5-diazabicyclo [4.3.0] -5-nonene), and the like can also be used. On the other hand, specific examples of the acid compound as the oxidation promoting catalyst include acetic acid, propionic acid, butyric acid, valeric acid,
Organic acids such as maleic acid, stearic acid, hydrochloric acid, nitric acid,
And inorganic acids such as sulfuric acid and hydrogen peroxide. Particularly preferred acid compounds are propionic acid, hydrochloric acid and hydrogen peroxide.

The amount of the amine compound added to the phenylsilyl group-crosslinked polysilazane may be 1 ppm or more, preferably 100 ppm to 100%, based on the weight of the phenylsilyl group-crosslinked polysilazane. An amine compound having a higher basicity (pKb value in an aqueous solution) and a higher boiling point tends to promote ceramic formation. The amount of the acid compound added to the phenylsilyl group-crosslinked polysilazane may be 0.1 ppm or more based on the weight of the phenylsilyl group-crosslinked polysilazane, preferably 10 pp.
m to 10%. A particularly preferred amine compound in this embodiment is tripentylamine, and the acid compound is propionic acid.

The phenylsilyl group-crosslinked polysilazane or a modified product thereof is exposed to a steam atmosphere after application to convert the phenylsilyl group-crosslinked polysilazane or a modified product thereof into a ceramic. For this contact, a humidifying furnace or steam is generally used. Specifically, steam is introduced into the solvent drying zone during coating, and steam is introduced therein (at a temperature of 50 to 10).
0 ° C., relative humidity of 50 to 100% RH) or a separately provided humidifying furnace (temperature of 50 to 100 ° C., relative humidity of 50 to 100% RH) with a residence time of 10 to 60 minutes. Alternatively, a method in which steam is passed through a solvent drying zone (temperature: 50 to 100 ° C., relative humidity: 50 to 100% RH) in which steam that has passed during drying of the solvent after coating is passed again with a residence time of 10 to 60 minutes can be considered. When the temperature is low, the treatment can be carried out simply in a vessel containing steam or in the atmosphere. The temperature range for contact with the water vapor can range from room temperature (about 20 ° C.) to the heat resistant temperature of the substrate. The humidity range in contact is about 0.1% R
H to 100% RH.

By the above-mentioned exposure treatment to a water vapor atmosphere, Si—N, Si—H, NH bonds and the like contained in the phenylsilyl group-crosslinked polysilazane or a modified product thereof disappear, and the Si—O bond is mainly contained. A tough ceramic film having a three-dimensional structure and remaining organic components is formed.
Since this SiO ₂ film is derived from a phenylsilyl group-crosslinked polysilazane, nitrogen is contained in an atomic percentage of 0.005 to 5%.
contains. If the nitrogen content is more than 5%, the film is not sufficiently ceramicized, and the desired effects (eg, gas barrier properties and abrasion resistance) cannot be obtained. On the other hand, it is difficult to make the nitrogen content less than 0.005%.

The thickness of the SiO ₂ film obtained by one application by these methods is preferably in the range of 50 to 5 μm, more preferably 100 to ₂ μm. Film thickness 5
If the thickness is larger than μm, cracks often occur during the heat treatment, and the flexibility is further deteriorated, and cracking or peeling due to bending or the like is likely to occur. Conversely, if the film thickness is less than 50 °, desired effects, for example, desired gas barrier properties and abrasion resistance cannot be obtained. This film thickness can be controlled by changing the concentration of the coating composition. That is, when it is desired to increase the film thickness, the solid content concentration of the coating composition can be increased (the solvent concentration can be decreased).
Further, the film thickness can be further increased by applying the coating composition a plurality of times. Hereinafter, the present invention will be further described with reference to examples.

[0072]

EXAMPLES Reference Example 1 [Synthesis of Perhydropolysilazane] A 1-liter four-necked flask was equipped with a gas blowing tube, a mechanical stirrer, and a dewar condenser. After the inside of the reactor was replaced with deoxygenated dry nitrogen, 490 ml of degassed dry pyridine was put into a four-necked flask, and this was cooled with ice. Then the addition of dichlorosilane 51.9g white solid adduct _{(SiH 2 C1 2 · 2C 5} H 5 N) was produced. The reaction mixture was cooled on ice, and ammonia 5 was passed through a sodium hydroxide tube and an activated carbon tube while stirring.
After blowing in 1.0 g, the mixture was heated at 100 ° C. After the completion of the reaction, the reaction mixture was centrifuged, washed with dry pyridine, and then filtered under a dry nitrogen atmosphere to remove the filtrate.
0 ml was obtained. The solvent was removed from 5 ml of the filtrate under reduced pressure to obtain 0.102 g of resinous solid perhydropolysilazane.
The number average molecular weight of the obtained polymer was 1,120 as measured by GPC based on polystyrene. IR (infrared absorption) spectrum (solvent: dry xylene; concentration of perhydropolysilazane: 10% by weight)
Wave number (cm ^-1 ) 3380, and absorption based on NH of 1180: absorption based on Si-H of 2160: 1060 to 1060
It showed an absorption based on Si-N-Si of 800. FIG. 1 shows the IR spectrum.

REFERENCE EXAMPLE 2 [Synthesis of polymethyl (hydro) silazane] A four-necked flask having an inner volume of 500 ml was equipped with a gas injection tube, a mechanical stirrer, and a dewar condenser. After the inside of the reactor was replaced with deoxygenated dry nitrogen, methyldichlorosilane (CH ₃ SiHC) was placed in a four-necked flask.
1 _2, 24.3 g, was placed 0.221 mol) and dry dichloromethane 300 ml. The reaction mixture was ice-cooled, and ammonia was decomposed by blowing 20.5 g (1.20 mol) of dry ammonia together with nitrogen gas while stirring. After completion of the reaction, the reaction mixture was centrifuged and then filtered. The solvent was removed from the furnace liquid under reduced pressure to obtain 8.79 g of polymethyl (hydro) silazane as a colorless liquid. The number average molecular weight of the product was 310 as measured by freezing point depression method (solvent: dry benzene). A gas inlet tube, a thermometer, a condenser, and a dropping funnel were attached to a four-necked flask having an inner volume of 100 ml, and the inside of the reaction system was replaced with arcon gas. A four-necked flask was charged with 12 ml of tetrahydrofuran and 0.189 g (4.71 mol) of potassium hydroxide,
Magnetic stirring was started. 5.00 g of the above-mentioned polymethyl (hydro) silazane and 50 ml of dry tetrahydrofuran were put into a dropping funnel, and this was dropped into potassium hydroxide. After reacting at room temperature for 1 hour, 1.60 g (11.3 mmol) of methane iodide and 1 ml of dry tetrahydrofuran were put into a dropping funnel, and this was added dropwise to the reaction solution. After reacting at room temperature for 3 hours, the solvent of the reaction mixture was removed under reduced pressure, 40 ml of dry n-hexane was added, centrifuged, and filtered. Removal of the solvent from the furnace under reduced pressure gave 4.85 g of polymethyl (hydro) silazane as a white powder. When the number average molecular weight of the obtained polymer was measured by a GPC method using polystyrene as a reference, it was found to be 1060.
Met. The IR (infrared absorption) spectrum (solvent: dry xylene; polymethyl (hydro) silazane concentration: 10% by weight) has a wave number (cm ^-1 ) of 3380, and an N of 1180.
Absorption based on -H: Absorption based on 2140 Si-H:
Absorption based on Si-CH ₃ of 1260: 2950 of the C-
H-based absorption was shown. FIG. 2 shows the IR spectrum.

Example 1 10 g of the perhydropolysilazane synthesized in Reference Example 1 and 80 g of xylene were introduced into a glass beaker having a capacity of 300 ml. 10 g of triethylamine was added thereto, and the mixture was stirred well with a stirrer to prepare a polysilazane solution. Next, 17 g of triethylamine and 3.0 g of 1,4-bis (hydroxydimethylsilyl) benzene (manufactured by Chisso Corporation) were mixed well and injected into a glass burette having a capacity of 50 ml. This was slowly added dropwise to the above-mentioned polysilazane solution over about 10 minutes while sufficiently stirring with a stirrer.
The reaction proceeded with a mild exotherm and evolution of gas.
After completion of the dropwise addition, the mixture was left for about 30 minutes while stirring. Subsequently, triethylamine in the solution was distilled off using a rotary evaporator to obtain a 10% by weight phenylsilyl group-crosslinked polysilazane xylene solution. The number average molecular weight of the obtained phenylsilyl group-crosslinked polysilazane was measured by a GPC method using polystyrene as a standard.
500. The IR (infrared absorption) spectrum shows the absorption of polysilazane, ie, a wavenumber (cm ^-1 ) of 3380, and an absorption based on NH of 1180, and an Si-H of 2160.
, An absorption based on Si-N-Si of 1060 to 800, plus an absorption based on C-H at a wave number (cm ^-1 ) of 2950, an absorption based on Si-Me of 1250, 113
Absorption based on Si-Ph of 0, Si-OS of 1080
An absorption based on i was observed. FIG. 3 shows the IR spectrum. ^{When the 1} H-NMR spectrum (solvent: a mixture of dry xylene and CDCl ₃ (1: 2 by weight); perhydropolysilazane concentration: 10% by weight) was measured, polysilazane, that is, 4.5 to 5.3 ppm of Si was obtained. -H1
1H, 4.3-4.5 assigned to the group and Si-H2 group
1H attributed to ppm of Si-H3, 0.8-1.9.
In addition to 1H attributable to the N—H group in ppm, 7.5 to 7.5
1H attributable to CH group of phenyl group at 7.7 ppm
And 1H attributed to 0.3-0.5 ppm of Si-Me group was observed. FIG. 4 shows the ¹ H-NMR data.
The obtained phenylsilyl group-crosslinked polysilazane (10 wt% xylene solution) was allowed to stand at room temperature for 20 days in an air atmosphere, and the number average molecular weight was measured.

Example 2 10 g of polymethyl (hydro) silazane synthesized in Reference Example 2 and 80 g of xylene in a glass beaker having a capacity of 300 ml.
Was introduced. 10 g of triethylamine was added thereto, and the mixture was stirred well with a stirrer to prepare a polysilazane solution. Next, 17 g of triethylamine and 3.0 g of 1,4-bis (hydroxydimethylsilyl) benzene (manufactured by Chisso Corporation) were mixed well and injected into a glass burette having a capacity of 50 ml. This was slowly added dropwise to the above-mentioned polysilazane solution over about 10 minutes while sufficiently stirring with a stirrer. The reaction proceeded with a mild exotherm and evolution of gas. After completion of the dropwise addition, the mixture was left for about 30 minutes while stirring. Subsequently, triethylamine in the solution was distilled off using a rotary evaporator to obtain a 10% by weight phenylsilyl group-crosslinked polysilazane xylene solution. The number average molecular weight of the obtained phenylsilyl group-crosslinked polysilazane was measured by GPC method using polystyrene as a reference, and was 1600. Obtained phenylsilyl group-crosslinked polysilazane (10% by weight xylene solution)
Was allowed to stand at room temperature and in an air atmosphere for 20 days, and the number average molecular weight was measured.

[Brief description of the drawings]

FIG. 1 shows an infrared absorption spectrum of perhydropolysilazane obtained in Reference Example 1.

FIG. 2 shows an infrared absorption spectrum of polymethyl (hydro) silazane obtained in Reference Example 2.

FIG. 3 shows an infrared absorption spectrum of a phenylsilyl group-crosslinked polysilazane obtained in Example 1.

FIG. 4 shows a ¹ H-NMR spectrum of the phenylsilyl group-crosslinked polysilazane obtained in Example 1.

Claims (3)

[Claims] 1. Mainly the following structural formula (1): Having a number average molecular weight of 100 to 500 having a skeleton represented by
At least a part of the polysilazane main chain of the formula (00) has the following structural formula (2): [In the structural formulas (1) and (2), R ¹ , R ^2, and R ³ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group other than these groups directly bonded to silicon. Phenylsilyl group-crosslinked polysilazane, which is a group having a carbon atom, an alkylsilyl group, an alkylamino group, or an alkoxy group. 2. Mainly the following structural formula (1): Having a number average molecular weight of 100 to 500 having a skeleton represented by
At least a part of the polysilazane main chain of 00 is represented by the following structural formula (2): [In the structural formulas (1) and (2), R ¹ , R ^2, and R ³ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group other than these groups directly bonded to silicon. Represents a group having a carbon atom, an alkylsilyl group, an alkylamino group, or an alkoxy group.] And a solvent. 3. Mainly the following general formula (1): Having a number average molecular weight of 100 to 500 having a skeleton represented by
And a polysilazane of the following formula (3): [In the above structural formulas (1) and (3), R ¹ , R ² and R ³ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group other than these groups directly bonded to silicon. Represents an alkylsilyl group, an alkylamino group, or an alkoxy group, which is a carbon group, and 1,4-bis (hydroxysilyl) benzene represented by the following formula: A method for producing a phenylsilyl group-crosslinked polysilazane.