JP2003347294A - Method for accelerating conversion of polysilazane coating film into siliceous material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an even-thickness siliceous ceramic film which is excellent in minuteness and durability on the surface of a substrate or the like by accelerating the conversion of polysilazane or a modified material thereof into the siliceous ceramic film in a short time by a comparatively easy means. <P>SOLUTION: A coating film comprising polysilazane or the modified material thereof as a main material is formed on the surface of the substrate. The coating film is then cured and treated with high temperature water comprising ammonium salt. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for uniformly forming a dense and durable siliceous ceramic film on a surface of a substrate or the like.

[0002]

2. Description of the Related Art Silica-based films have excellent properties such as heat resistance, abrasion resistance, corrosion resistance, high insulation properties and hydrophilicity. Interlayer insulating film, flattening film, passivation film, inter-element isolation insulator, dielectric film such as liquid crystal display device, plasma display panel (PDP), insulating film, partition film or protective film, and car body such as automobile It is used in various fields as a protective coating for various articles such as surfaces, interior and exterior of houses, glass products, mirrors, ceramics, plastic products, metal products, stone products, enamels, etc., or a hydrophilicity-imparting film. As a method of forming such a siliceous film on a substrate, there are PVD method (sputtering method, etc.),
Various methods such as a CVD method (chemical vapor deposition method), a sol-gel method, and a method of forming a coating film of polysiloxane or polysilazane or a modified product thereof and converting the formed coating film to a siliceous film by firing or the like. Methods are known. Among these methods, the PVD method and the CVD method have the problems that the equipment is expensive and the control for forming a good quality coating film is complicated. In the sol-gel method,
There is a problem that the required firing temperature is as high as 500 ° C. or higher.
Further, the method using polysiloxane has a problem that cracks occur due to a decrease in the thickness of the formed film. On the other hand, a method of applying a solution of polysilazane or a denatured product thereof and converting the formed coating film to a siliceous film (for example, Japanese Patent Application Laid-Open No. H7-45605, etc.) has excellent characteristics by firing at low temperature. In recent years, it has attracted particular attention because it can easily form a siliceous film having the same and the film quality of the formed siliceous film is excellent.

[0003] As a method of applying the solution of polysilazane or a modified product thereof and converting the formed coating film to a siliceous film, for example, a polysilazane solution is applied on a base material, and heated to be applied. The solvent is removed from the membrane, then 35
A method is employed in which polysilazane is converted into a siliceous film by firing at a temperature of 0 ° C. or higher. In the conversion of polysilazane to siliceous material by such sintering, it is difficult to completely convert the polysilazane to a siliceous film by heating for a short time, and a long time sintering is required to achieve the complete conversion. Further, it is necessary to use a substrate having a relatively high heat-resistant temperature as a substrate, and it cannot be applied to a substrate whose appearance changes such as discoloration due to heating, thereby reducing its commercial value.

In order to solve such a problem, Japanese Patent Laid-Open Publication No.
In JP-A-2001-335950, a coating film-forming composition containing polysilazane or a modified product thereof formed on a substrate as a main component is applied, cured, and then treated with high-temperature water to form a coating on the substrate. A method for forming a siliceous ceramic layer has been proposed. In this method, by performing treatment with high-temperature water, a siliceous ceramic layer can be formed at an early stage, and by using a composition containing polysilazane or a modified product thereof that can be fired at low temperature, the method can be used at low temperature. It is also described that a dense siliceous ceramic layer can be formed. As a composition which can be fired at a low temperature, a composition comprising polysilazane or a modified product thereof and an amine and / or an acid and a composition comprising polysilazane or a modified product thereof and metal particles are mentioned.

[0005] On the other hand, the present inventor has proposed a body / wheel of a car, a train, an aircraft, etc., a plumbing product such as a house interior / exterior, a toilet, a kitchen, a lavatory, a bathtub, a signboard, a sign, a plastic product, a glass product, a gravestone. It has been found that a coating film having a hydrophilic and excellent antifouling effect can be formed by coating the surface of a stone material such as a metal or a metal with a coating solution containing an inorganic polysilazane, a diluting solvent and a catalyst, and drying at room temperature. , Japanese Patent Application 2001-131491
No. (PCT / JP02 / 04069).
This coating liquid is specifically represented by the general formula (I):

[0006]

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Is dissolved in a diluting solvent such as a mineral spirit or a paraffinic solvent, and a catalyst such as 4,4'-trimethylenebis (1-methylpiperidine) is added to the inorganic polysilazane. On the other hand, it is formed by mixing 0.5 to 10% by weight. In a coating film formed by applying this coating liquid to a substrate and drying at room temperature, the inorganic polysilazane is converted into a dense siliceous film by the action of a catalyst, and a dense and strongly hydrophilic coating film is formed. The conversion to the siliceous film depends on the type of the inorganic polysilazane, the catalyst and the like, but usually takes about one to two weeks.

[0008]

Problems to be Solved by the Invention
In the method described in JP-A-335950, although a dense and excellent durability is generally obtained as a siliceous film, polysilazane or polysilazane may be obtained depending on conditions or conditions under which a coating film containing polysilazane or a modified product thereof is formed. Alternatively, there is a problem that the modified product is not sufficiently converted into a siliceous ceramic film and remains partially. For example, when a siliceous film is formed on a curved substrate such as a curved mirror, a portion of the silazane that has not been converted into silicon oxide remains on a molecular level after treatment with high-temperature water, and this denaturation occurs. For example, a portion that does not flow out when placed in a continuous wet state, so that sufficient performance in terms of compactness and durability is not necessarily obtained.

In addition, when a photocatalyst-containing layer is formed on the outer surface of the siliceous ceramic film to obtain a coating, if a component such as ammonia remains near the surface of the siliceous ceramic film, the photocatalyst-containing layer is thereby formed. In some cases, the curing reaction for forming the photocatalyst is hindered, and the adhesion between the siliceous ceramic layer and the photocatalyst-containing layer may be insufficient.

On the other hand, as described above, Japanese Patent Application No. 2001-1
It takes about one to two weeks to convert the coating solution proposed in Japanese Patent No. 31491 to siliceous by drying at room temperature to act as a catalyst by the action of a catalyst.
In the case of automobile bodies, etc., they may be brought into the consumer immediately after the coating, and dirt may adhere to them by being exposed to rainwater before a sufficient hydrophilic antifouling silica-based film is formed. As a result, there are cases where sufficiently dense and homogeneous silica cannot be obtained.

An object of the present invention is to provide a method for forming a siliceous ceramic film that does not have such problems. More specifically, a relatively easy means, and in a short time, sufficiently convert polysilazane or a modified product thereof into a siliceous ceramic film, and form a dense and durable siliceous ceramic on the surface of a substrate or the like. It is an object of the present invention to provide a method for forming a film uniformly.

[0012]

In order to achieve the above object, the present invention provides a method for curing a coating film containing polysilazane or a modified product thereof as a main component, and then comprising the cured film containing an ammonium salt. An object of the present invention is to provide a method for promoting the conversion of a coating film containing polysilazane or a modified product thereof into a siliceous substance by treating with high-temperature water.

When the treatment with high-temperature water containing the ammonium salt of the present invention is performed, a denser and more uniform siliceous film can be obtained as compared with the treatment with high-temperature water to which no ammonium salt is added. In addition, a highly durable siliceous ceramic layer can be formed even on a curved substrate. In particular, when ammonium carbonate is used as the ammonium salt, a remarkable effect can be obtained.

When the photocatalyst-containing layer is coated on the outer surface of the silica-based ceramic film, the silica-based ceramic film formed by the method of the present invention has ammonia or the like near the surface of the layer which adversely affects the curing reaction of the photocatalyst-containing layer. And the effect that the curing reaction when the photocatalyst-containing layer is formed is not hindered can be obtained.

Further, the inorganic polysilazane is dissolved in a diluting solvent such as a mineral spirit or a paraffinic solvent,
A catalyst such as 4′-trimethylenebis (1-methylpiperidine) is added to the inorganic polysilazane in an amount of 0.5 to 10% by weight.
No. 2001-131491 (PCT /
JP02 / 04069) for the coating liquid
According to the method of the present invention, the conversion to siliceous, which has conventionally required one to two weeks, can be performed in about two hours.

Further, since the siliceous ceramic film formed by the method of the present invention is a very dense film, it is necessary to protect the substrate from the oxidative decomposition of the photocatalyst even with a thin film that does not impair the light transmittance. Further, the film has excellent durability in a wet state, and has good adhesion to the substrate and the photocatalyst-containing layer, so that it can sufficiently withstand outdoor use. In addition, since it has excellent heat resistance, it does not crack even when the photocatalyst-containing layer is fired, and because it has excellent bending resistance, it does not crack even when it is bent. The substrate is extremely resistant to scratches because of its excellent properties and high film hardness even in a thin film.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail.

In order to form a siliceous ceramic film by the method of the present invention, first, a film-forming composition containing polysilazane or a modified product thereof as a main component is spray-coated on a surface of a substrate to be coated. Dip coat, spin coat,
Apply by an appropriate method such as flow coat, roll coat, etc.
After forming a coating film containing polysilazane or a modified product thereof as a main component, curing the coating film, the coating film may be treated with high-temperature water containing an ammonium salt to be converted into a siliceous ceramic film. At this time, the application may be performed once or two or more times. The coating thickness varies depending on the purpose of use of the formed siliceous ceramic film. For example, when used for an intermediate layer, it is usually 0.05 to 0.2 μm,
Usually 0.1 when used for surface protective coatings
１．０1.0 μm.

The polysilazane in the present invention is not particularly limited, but has at least Si in the molecule.
-H bonds or those having an N-H bond are preferable, and polysilazane may be used alone, or a copolymer of polysilazane and another polymer or a mixture of polysilazane and another compound may be used. It may be chain-like, cyclic, or may have a crosslinked structure,
These may be used alone or in a mixture.
The polysilazane in the present invention may be either inorganic or organic. Examples of these polysilazanes or modified polysilazanes include the following. However, these are given only for illustrative purposes, and the polysilazane and its modified product in the present invention are not limited to the following.

(1) General formula (I):

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Perhydropolysilazane (inorganic polysilazane) containing a linear structure having the structural unit represented by

(2) Mainly the general formula:

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(Wherein 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 other than these groups, directly bonded to silicon such as a fluoroalkyl group) Represents an alkylsilyl group, an alkylamino group or an alkoxy group, provided that at least one of R ¹ , R ² and R ³ is a hydrogen atom. A polysilazane having a skeleton and a number average molecular weight of about 100 to 50,000 or a modified product thereof. (Special Publication 63-163
No. 25, D.C. Seeferth et al., Communi
site of Am. Cer. Soc. , C-1
3, January 1983; Seeferth
Et al., Polym. Prepr. Am. Chem. So
c. , Div. Polym. Chem. , 25,10
(1984), JP-A-61-89230, etc.)

(3) General formula:

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A polyorgano (hydro) silazane having a crosslinked structure represented by the following formula (D. Seeferth)
Communication of Am. Cer. S
oc. C-132, July 1984).

(4) Polysilazane having the following structure (JP-A-49-69717).

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(5) The following structure

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(Wherein M, which is a metal atom in the side chain, may be crosslinked), a polymetallosilazane containing a metal atom, and the repeating unit is [(SiH ₂ ) _n (NH) _m ]
And ((SiH ₂ ) _r O] (wherein n, m and r are 1, 2 or 3 respectively) (JP-A-62-195024), polysilazane and boron. A polyborosilazane having excellent heat resistance produced by reacting a compound (JP-A-2-84437);
Polymetallosilazane produced by reacting polysilazane and metal alkoxide (JP-A-63-81212,
JP-A-63-191832 and JP-A-2-77427), an inorganic silazane high polymer or a modified polysilazane having an increased molecular weight or improved hydrolysis resistance (JP-A-Hei.
-138108, 1-138107, 1-20
No. 3429, No. 1-203430, No. 4-63833
And JP-A-3-320167), and copolymerized silazanes obtained by introducing an organic component into polysilazane and advantageous for increasing the film thickness (JP-A-2-175726, JP-A-5-86200, and JP-A-5-33).
Nos. 1293 and 3-31326), and polysilazanes in which a catalytic compound for accelerating ceramic formation is added or added to polysilazanes (Japanese Patent Laid-Open No. 5-38827).
Nos. 6-122852, 6-299118, 6-306329, 6-240208, and 7-1
96986), more specifically, polysilazane with silicon alkoxide (JP-A-5-238827) and polysilazane with glycidol (JP-A-6-12).
No. 2852), acetylacetonate complex-added polysilazane (JP-A-6-306329), metal carboxylate-added polysilazane (JP-A-6-299118), and the like, as described in JP-A-9-31333. Various polysilazanes or modified products as described above,
Polysilazane compositions containing amines and / or acids, alcohols such as methanol in perhydropolysilazane (JP-A-5-345826) or hexamethyldisilazane (JP-A-4-63833).
Is a modified polysilazane obtained by adding to a terminal N atom.

[0029] Among these polysilazanes or modified products,
Perhydropolysilazane, an inorganic polysilazane, is preferred. Further, a catalyst or a catalytic compound that converts polysilazane or a modified product thereof into silica may be added or added to the coating film forming composition, if necessary. These catalysts or catalytic compounds may be any of those including conventionally known ones.
JP-A-2001-335950 and the like, amines, acids, metal particles, metal carboxylate salts such as palladium propionate described in JP-A-6-299118 and the like, or Japanese Patent Application No. 2001-131149 (P.
CT / JP02 / 04069).
-Methylpiperazine, 1-methylpiperidine, 4,4 '
-Trimethylene dipiperidine, 4,4'-trimethylenebis (1-methylpiperidine), diazabicyclo-
[2,2,2] octane, cis-2,6-dimethylpiperazine, 4- (4-methylpiperidine) pyridine, pyridine, dipyridine, α-picoline, β-picoline, γ-
Picoline, piperidine, lutidine, pyrimidine, pyridazine, 4,4′-trimethylenedipyridine, 2- (methylamino) pyridine, pyrazine, quinoline, quinoxaline, triazine, pyrrole, 3-pyrroline, imidazole, triazole, tetrazole, 1- N-heterocyclic compounds such as methylpyrrolidine; methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, pentylamine, dipentylamine, triethylamine Pentylamine, hexylamine, dihexylamine, trihexylamine, heptylamine, diheptylamine, octylamine, dioctylamine, trioctylamine Amines such as min, phenylamine, diphenylamine and triphenylamine;
BU (1,8-diazabicyclo [5,4,0] 7-undecene), DBN (1,5-diazabicyclo [4,3,
0] 5-nonene), 1,5,9-triazacyclododecane, 1,4,7-triazacyclononane and the like. The amount of these catalysts or catalytic compounds to be added is appropriately determined. For example, Japanese Patent Application No. 2001-1314
No. 91 (PCT / JP02 / 04069), the composition for forming a coating film is preferably about 0.5 to 10% by weight based on the inorganic polysilazane pure content.

The polysilazane or a modified product thereof, a catalyst and the like are dissolved in a solvent to form a coating film forming composition. As the solvent, any solvent can be used as long as it can dissolve polysilazane or its modified product, catalyst, and the like. Examples of the solvent include petroleum solvents such as mineral spirits, paraffin solvents, aromatic solvents, and cycloaliphatic solvents.

The composition for forming a coating film containing polysilazane or a modified product thereof as a main component is applied to a substrate and dried to form a coating film. The drying temperature of the coating film may be any temperature, and is usually from room temperature to higher temperature. After the dried coating film is cured, it is treated with high-temperature water to which an ammonium salt is added. The curing temperature varies depending on the composition of the coating film forming composition, and it is usually preferable to perform the curing at a temperature at which the coating film is cured and fired.

The high-temperature water used in the present invention is desirably purified water. However, it does not adversely affect the siliceous ceramic film itself after the treatment, and it does not affect the outer surface of the photocatalyst-containing layer and the like. Any material may be used as long as it does not adversely affect the outer surface layer such as adhesion to the formed layer. As the water that has not been subjected to the pure water treatment, for example, tap water or the like can be used. In addition, the temperature of the high-temperature water used for the treatment is usually preferably in a liquid state having a high energy and a high energy close to a boiling state, specifically, preferably 90 ° C or higher, more preferably 96 ° C or higher. is there.

Examples of the ammonium salt added to and contained in high-temperature water include ammonium carbonate, ammonium nitrate, ammonium chloride, ammonium bromide, ammonium acetate, ammonium sulfate, ammonium hydrogen sulfate, ammonium hydrogen carbonate, diammonium hydrogen phosphate, and the like. Ammonium dihydrogen phosphate, ammonium fluoride,
Examples thereof include ammonium borate, ammonium formate, and diammonium oxalate, and among them, ammonium carbonate is particularly preferable.

The siliceous ceramic film thus obtained is dense and excellent in durability, heat resistance, abrasion resistance, corrosion resistance, insulation, hydrophilicity, etc., and has high coating hardness even in a thin film. In addition, it is a coating that is extremely suitable for protecting and soiling the substrate. For this reason, metal, glass, plastic,
It can be used to protect or stain the surface of various base materials such as stones, enamel materials, and ceramics, and can also be used as an insulating film, a dielectric film, and the like.

If necessary, a further coating may be provided on the surface (outer surface) of the siliceous ceramic film. For example, as such a coating, a photocatalyst containing layer containing a photocatalyst such as titanium dioxide can be mentioned. In order to obtain a coating on which a photocatalyst-containing layer containing a photocatalyst such as titanium dioxide is formed, a spraying method in which a powder such as titanium dioxide is melted and sprayed, or a CV in which titanium dioxide is deposited through a chemical reaction, is used.
It may be formed by an appropriate method such as a D method (chemical vapor deposition method), a sputter deposition method in which titanium dioxide or the like is sputter-evaporated and deposited, or a vacuum deposition method. If it is made into a composition and it is applied by dipping, spraying, flow coater, etc.,
This coating method is usually preferred because a uniform and smooth coating can be easily formed.

When the photocatalyst-containing layer is formed by such a method, it is preferable to use a silicone compound as a binder. When the photocatalyst-containing layer is formed using a silicone compound, for example, a coating composition comprising a mixture of a hydrolyzate of an alkoxysilane such as an organopolysiloxane or tetraethoxysilane and a titania sol is applied, and the temperature is 50 ° C. or higher. And can be formed by heating.

Titanium dioxide as a photocatalyst may be of rutile type, but is preferably of anatase type because of its high activity. This titanium dioxide has a wavelength range of 300 to 400 n.
Irradiation of ultraviolet light around m activates titanium dioxide, which produces a strong oxidizing power, decomposes contaminants attached to the surface, and activates the surface at a contact angle with water that is almost equal to that of water. It is hydrophilized to about 0 to 20 degrees. Such hydrophilicity makes it difficult for contaminants to adhere, and even if it adheres, it will not be easily washed away by rainfall or the like. Furthermore, even if the conditions for dew condensation are satisfied, the surface that has been hydrophilized makes it difficult for dew condensation to occur because moisture adhering to the surface is uniformly diffused to the surface.

As described above, the siliceous ceramic film obtained according to the present invention is used as a surface layer, an intermediate layer or an underlayer of a substrate, and is used for the substrate, or various products, in terms of stain resistance, stain resistance, and stain resistance. Properties such as fogging, heat resistance, abrasion resistance, corrosion resistance, and high insulation can be imparted. Examples of applications to which the siliceous ceramic obtained by the present invention is applied include polymers, metals, various types of buildings made of glass, etc., and all materials such as structures, for example, building materials, building exterior materials,
Windows, signs, traffic signs, translucent sound insulation for roads and railways, sound insulation, guardrails, lighting covers, bridges, fences,
A railing, a line-of-sight guide, a reflector used for them, a curve mirror, a bathroom mirror, and the like. In addition, the present invention is also applicable as an anti-fouling coating for automobile bodies, dentures, various display devices, insulating films such as semiconductor elements, dielectric films, protective films, and the like.

[0039]

Embodiments of the present invention will be specifically described below. However, the present invention is not limited to the following examples.

Example 1 10% by weight of perhydropolysilazane and 0.5% by weight
Xylene solution containing palladium propionate
Spin coating (500 rpm,
After 20 seconds), in an atmosphere of 22 ° C. and 50% relative humidity, 3
Heat treatment was performed at 50 ° C. for 1 minute. The silica conversion at this time was 2.1. This substrate was immersed in a 10% by weight aqueous solution of ammonium carbonate, and treated for 1 hour in a boiling state. After the treatment, the membrane was washed with pure water and dried to obtain a siliceous ceramic film having a thickness of 0.2 μm. The silica conversion of this siliceous ceramic membrane was measured and found to be 18.6.
Here, the silica conversion was evaluated semi-quantitatively by IR spectrum. Absorption of 1080 cm ^-1 SiO, and 9
Using the absorption of SiN at 60 cm ⁻¹ , the silica conversion = S
Absorbance of iO / absorbance of SiN. It can be seen that the larger this value is, the more the conversion of polysilazane to silica is progressing.

Comparative Example 1 A coated substrate was prepared in the same procedure as in Example 1, and this substrate was immersed in pure water and treated for 1 hour in a boiling state. After the treatment, it was dried, and the silica conversion was measured to be 4.2.

Comparative Example 2 A coated substrate was prepared in the same procedure as in Example 1, and this substrate was immersed in a 10% by weight aqueous solution of pyridine and treated for 1 hour in a boiling state. After the treatment, the resultant was washed with pure water and dried, and the silica conversion was measured, and it was 4.8.

Example 2 A 5% by weight polysilazane solution (model number: NP-110) from Clariant Japan KK was spin-coated (500 rpm, 20 seconds) on a 4-inch silicon wafer, and then placed in an atmosphere at 22 ° C. and 50% relative humidity. At 350 ° C. for 1 minute. At this time, the conversion rate of silica was 2.2. This substrate was immersed in a 10% by weight aqueous solution of ammonium nitrate and subjected to a treatment in a boiling state for 1 hour. After the treatment, the resultant was washed with pure water and dried to obtain a 0.1 μm-thick siliceous ceramic film. The silica conversion of this siliceous ceramic membrane was measured to be 10.3.

[0044]

According to the present invention, a coating film containing polysilazane or a modified product thereof as a main component is cured as required, and then treated with high-temperature water containing an ammonium salt, whereby a highly dense coating is formed on the substrate. Thus, a uniform siliceous ceramic film having few SiN bonds can be formed. This highly dense and uniform siliceous ceramic film having few SiN bonds is formed on a curved surface or the like in the same manner as a flat surface, and is excellent even when a siliceous ceramic film is formed on a curved surface such as a curved mirror. A siliceous ceramic film exhibiting the above characteristics is formed. The obtained siliceous ceramic film is a film with excellent heat resistance, abrasion resistance, corrosion resistance, insulation, hydrophilicity, antifouling properties, insulation, etc. It can be used as a surface film, an intermediate film or a base film.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Toru Funayama             3810 Chihama, Daito-cho, Ogasa-gun, Shizuoka Prefecture Clarian             To Japan Co., Ltd. F term (reference) 5F058 AC03 AF04 AG01 AG10 AH02                       AH03 BA06 BA09 BC05 BF46                       BH01 BH20 BJ02 BJ03

Claims (2)

[Claims] 1. A polysilazane or a modified product thereof, comprising the steps of curing a coating film containing polysilazane or a modified product as a main component and treating the cured film with high-temperature water containing an ammonium salt. Method for promoting the conversion of a coating film containing as a main component into siliceous. 2. The method according to claim 1, wherein the ammonium salt is ammonium carbonate.