JPH07292321A - Composition for coating - Google Patents

Abstract

PURPOSE:To provide the subject composition comprising the solution of a specific polysilazane and an acrylic resin and giving coating films excellent in heat resistance, hardness, adhesivity, flexibility, transparency, film thickness limit, and price. CONSTITUTION:This composition comprises the solution of (A) a polysilazane having a main skeleton comprising the units of the formula (R<1>-R<3> are H, alkyl, alkenyl, etc.; but at least one of R<1>-R<3> is H) and having a number-average mol. wt. of 100-50000 (preferably a perhydropolysilazane wherein all or almost all of R<1>-R<3> are H). The composition is preferably prepared by dissolving the components A and B in a solvent stably dissolving both the components A and B, respectively, and subsequently mixing both the prepared solutions with each other. When prominence is given to the flexibility, the component A is preferably compounded in an amount of 3-30wt.% per 100wt.% of the whole solid contents, and when prominence is also given to the hardness, etc., the component A is preferably compounded in an amount of 30-97wt.% per 100wt.% of the whole solid contents.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition capable of forming a coating film which is excellent not only in heat resistance, hardness and adhesion but also in flexibility, film thickness limit and low cost.

[0002]

2. Description of the Related Art Organic paints are not sufficient for obtaining high heat resistance, wear resistance and corrosion resistance, and ceramic coatings are used. Conventionally, as a method of forming a ceramic coating, PVD (sputtering method, etc.),
Known are CVD, sol-gel method, polytitanocarbosilane-based paint, poly (dicyl) silazane-based paint, polysilazane-based paint, polymetallosilazane-based paint, and the like.

On the other hand, in order to obtain flexibility and transparency, various organic paints are known in which an acrylic resin is used and various fillers are added as needed. Further, a heat-resistant coating material has been proposed in which a ceramics precursor resin made of a silicon compound such as polycarbosilane resin, polysilazane resin and polyborosiloxane resin, a fluororesin, an inorganic filler and the like are blended (JP-A-4-168175). And No. 5-156176).

[0004]

Although the ceramic coating is excellent in heat resistance, hardness, adhesion, etc., it is insufficient in flexibility, film thickness limit and cost. On the other hand, acrylic resin-based paints are excellent in flexibility, film thickness limit, price, and the like, and the hardness is improved to some extent by adding an inorganic filler or a curing agent, but there is a limit, and heat resistance, adhesion, etc. are limited. Is insufficient.

Further, since the heat-resistant paints prepared by mixing the ceramic precursor resin and various resins all use silicon compounds containing an organic group, the effects on heat resistance, hardness and adhesion are not yet sufficient. In particular, pinholes and cracks accompanying shrinkage occur due to desorption of organic groups during baking, so that a sufficiently dense film cannot be obtained and adhesion to the substrate is also insufficient. Furthermore, it is essential to add an inorganic filler or glass fiber in the heat-resistant paint, and although hardness can be improved by these, since it does not contribute to adhesion at all, the more it is added, the better the adhesion. The flexibility and flexibility are reduced.

The present invention solves these problems and provides a coating film having an inorganic / organic hybrid structure which is excellent in heat resistance, hardness and adhesion, as well as flexibility, transparency, film thickness limit and cost. It is an object to provide a coating composition to be provided.

[0007]

In order to achieve the above object, the present invention comprises (1) a general formula (I):

[0008]

[Chemical 2]

(However, 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 in which the group directly bonded to silicon is carbon. , An alkylsilyl group, an alkylamino group, and an alkoxy group, provided that R ¹ and R
^At least one of ² and R ³ is a hydrogen atom. The present invention provides a coating composition, which is a solution in which a polysilazane having a main skeleton composed of a unit represented by the formula (1) and having a number average molecular weight of 100 to 50,000 and an acrylic resin are dissolved. Also provided is (2) the coating composition (1) in which the acrylic resin contains a methyl methacrylate component.

The polysilazane to be used must be a polysilazane having at least a Si--H bond or an N--H bond in the molecule, and in particular, R ¹ , R ² in the general formula (I),
Inorganic polysilazanes (perhydropolysilazanes) in which all or most of R ³ are hydrogen atoms [eg, Japanese Patent Publication No.
3-16325, JP-A-1-138108, 1-
No. 138107, No. 4-63833, and Japanese Patent Application No. 3-32.
No. 0167] or a polysilazane close thereto (for example, random copolymer silazane described in JP-A-3-31326, polysiloxazane disclosed in JP-A-62-195024,
Polymetallosilazanes of JP-A-2-77427 are preferable, but polysilazane alone, a copolymer of polysilazane and another polymer, a mixture of polysilazane and another compound, polysilazane, particularly inorganic polysilazane It can be used as long as the features are not lost.

The polysilazanes to be used include those having a chain structure, a cyclic structure, or a crosslinked structure, or those having a plurality of these structures simultaneously in the molecule, and these can be used alone or in a mixture. The following are typical examples of polysilazane to be used, but the polysilazane is not limited thereto.

The ^one having hydrogen atoms in R ¹ , R ² and R ³ in the general formula (I) is perhydropolysilazane, and its production method is described, for example, in Japanese Examined Patent Publication No. 63-16325, D.S. Seeferth et al. Communicatio
n of Am. Cer. Soc. , C-13, Jan
uary 1983. 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,

[0013]

[Chemical 3]

It can be represented by the chemical formula: An example of the structure of perhydropolysilazane is as follows.

[0015]

[Chemical 4]

In the general formula (I), R ¹ and R ² are hydrogen atoms,
The method for producing polysilazane having a methyl group in R ³ is
D. Seeferth et al., Polym. Prepr. , A
m. Chem. Soc. , Div. Polym. Che
m. , 25 , 10 (1984). The polysilazane obtained by this method has a repeating unit of −
(SiH ₂ NCH ₃₎ - is a chain polymer and a cyclic polymer, either no cross-linked structure.

In the general formula (I), R¹ And R³ Hydrogen atom,
R² Polyorgano (hydro) silazane having organic groups in
The manufacturing method of D. Seeferth et al., Polym. P
repr. , Am. Chem. Soc. , Div. Po
lym. Chem. ，25, 10 (1984), JP-A-SHO
61-89230. Those of these
The polysilazane obtained by the method includes-(R² SiHN
H)-as a repeating unit and the degree of polymerization is mainly 3-5.
With a cyclic structure of (R³ SiHNH) _X[(R
² SiH)_1.5 N]_1-XWith the chemical formula of (0.4 <x <1)
Having both chain structure and cyclic structure in the molecule
There is.

In the general formula (I), polysilazane having a hydrogen atom at R ¹ and an organic group at R ² and R ³ , and R ¹ and R ²
An organic group for R ³ and a hydrogen atom for R ³ is — (R ¹ R ²
SiNR ³ ) -is a repeating unit and the degree of polymerization is mainly 3
It has a cyclic structure of ~ 5. The polysilazane used is
As described above, it has a main skeleton composed of the unit represented by the general formula (I), but the unit represented by the general formula (I) may be cyclized as is clear from the above. When the moiety serves as a terminal group and such cyclization does not occur, the terminal of the main skeleton can be a group similar to R ¹ , R ² and R ³ or hydrogen.

Among the polyorgano (hydro) silazanes are D. Seeferth et al. Communicatio
n of Am. Cer. Soc. , C-132, Ju
ly1984. There are also those having a cross-linked structure in the molecule as reported in. An example is as follows.

[0020]

[Chemical 5]

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

[0022]

[Chemical 6]

Further, a polymetallosilazane containing a metal atom as shown in the following structure (in the formula, M which is a side chain metal atom may be crosslinked) can also be used as a starting material.

[0024]

[Chemical 7]

In addition, the repeating unit as reported in JP-A-62-195024 is [(SiH ₂ )
_n (NH) _m ] and [(SiH ₂ ) _r O] (wherein n, m and r are 1, 2 or 3, respectively), polysiloxazane described in JP-A-2-84437. Polyborosilazanes having excellent heat resistance, which are produced by reacting a polysilazane with a boron compound as reported, are reported in JP-A-63-81122, JP-A-63-191832, and JP-A-2-77427. Polymetallosilazanes produced by reacting such polysilazanes with metal alkoxides, JP-A-1-138108 and 1-1.
38107, 1-203429, 1-2034
No. 30, No. 4-63833, No. 3-320167, increased molecular weight (former 4 of the above publication), improved hydrolysis resistance (former 2), inorganic High silazane polymer and modified polysilazane, JP-A-2-1
No. 75726, No. 5-86200, No. 5-33129.
No. 3 and No. 3-31326, a copolymerized silazane which is advantageous in thickening a film by introducing an organic component into polysilazane, JP-A-5-238827 and JP-A-4-272.
No. 020, No. 5-93275, No. 5-214268.
No. 5,30,750, and No. 5,338,524, polysilazane can be applied to a metal such as plastics or aluminum in which a catalytic compound for promoting ceramization is added or added. Similarly, low temperature curing type polysilazane which is made into ceramics at a lower temperature can be used.

When polysilazane is mixed with acrylic resin particles, polysilazane is usually dissolved in a solvent. As the solvent, aliphatic hydrocarbons, alicyclic hydrocarbons, hydrocarbon solvents of aromatic hydrocarbons, halogenated hydrocarbons such as halogenated methane, halogenated ethane and halogenated benzene, aliphatic ethers, alicyclic ethers Ethers such as can be used. Preferred solvents are halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, ethylidene chloride, trichloroethane, tetrachloroethane, ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether,
1,2-dioxyethane, dioxane, dimethyldioxane, tetrahydrofuran, tetrahydropyran, cellosolve acetate, ethers such as carbitol acetate, pentanehexane, isohexane, methylpentane, heptane, isoheptane, octane, isooctane, cyclopentane, methylcyclopentane, Cyclohexane, methylcyclohexane, benzene, toluene,
Hydrocarbons such as xylene and ethylbenzene.

As the acrylic resin to be used, various resins can be used. For example, acrylic acid ester (as the alcohol residue, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group , T
-Butyl group, 2-ethylhexyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group and the like); methacrylic acid ester (alcohol residue is the same as above); 2-hydroxyethyl acrylate, 2
-Hydroxy-containing monomers such as hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and the like; acrylamide, methacrylamide, N-methylmethacrylamide,
Amide group-containing monomers such as N-methylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N, N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, and N-phenylacrylamide;
N, N-diethylaminoethyl acrylate, N, N-
Amino group-containing monomers such as diethylaminoethyl methacrylate; epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether; styrene sulfonic acid, vinyl sulfonic acid, and salts thereof (for example, sodium salt, potassium salt, ammonium salt) Etc.) and the like containing a sulfonic acid group or a salt thereof; such as crotonic acid, itaconic acid, acrylic acid, maleic acid, fumaric acid, and salts thereof (eg sodium salt, potassium salt, ammonium salt, etc.) Monomers containing carboxyl groups or salts thereof; monomers containing anhydrides such as maleic anhydride and itaconic anhydride; other vinyl isocyanates, allyl isocyanates, styrenes, vinyl methyl ethers, vinyl ethyl ethers, Alkenyl tris alkoxysilane,
It is made from a combination of monomers such as alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate and vinyl chloride. It is preferable that the content of the (meth) acrylic monomer component such as a derivative or a methacrylic acid derivative is 50 mol% or more, and particularly that the component of methyl methacrylate is contained. Also,
Fluorine-containing acrylic resin, for example, perfluoro-t-butyl polymethacrylate, polyperfluoroisopropyl methacrylate, hexafluoro-2-propyl polymethacrylate, trifluoroethyl polymethacrylate, fluorination of (meth) acrylic acid Ester polymers and the like have the advantage of excellent slidability and water repellency. The present invention is that polysilazane and an acrylic resin are compatible with each other, and further, if a suitable acrylic resin is selected, a stable coating solution can be obtained without degrading polysilazane, and thereby the transparency of both can be utilized as it is. It was made by discovering that it is possible to obtain a coating that complements the disadvantages of both. Solvents capable of dissolving acrylic resins include esters such as ethyl acetate and n-butyl acetate, glycol ethers such as cellosolve and cellosolve acetate, hydrogenated flames such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. Can be mentioned.

When a coating solution containing polysilazane and an acrylic resin is prepared, generally, the polysilazane solution and the acrylic resin solution may be mixed.
The blending amount of polysilazane and acrylic resin can be widely selected according to the application of the coating. For example, when importance is placed on flexibility, the total solid content [the total amount of polysilazane and acrylic resin] is 100% by weight. , Polysilazane 3
-30% by weight, and if hardness and heat resistance are important, the range of 30-97% by weight is preferable. [The amount of acrylic resin is the amount excluding the amount of polysilazane in the above solid content. As the solvent that dissolves the polysilazane and the acrylic resin, those that stably dissolve both the polysilazane and the acrylic resin are preferable, for example, xylene, toluene,
Butyl carbitol acetate, n-butyl acetate and the like are preferable. When a solvent is used, two or more kinds of solvents may be mixed in order to adjust the solubility of the polysilazane containing the acrylic resin and the evaporation rate of the solvent. The amount of solvent used (ratio) is selected according to the coating method used so that workability is improved, and according to the required film thickness,
The polysilazane may be mixed in the solvent in the coating composition in the range of about 99 to 5% by weight and the solid content concentration in the range of 1 to 95% by weight, although it depends on the average molecular weight, the molecular weight distribution and the structure of the polysilazane. . The solid content concentration is preferably 5 to 60% by weight. Further, in the present invention, although not essential, a suitable filler may be added if necessary. Examples of the filler include fine powders of oxide-based inorganic materials such as silica, alumina, zirconia, and mica, or non-oxide-based inorganic materials such as silicon carbide and silicon nitride. Depending on the application, it is also possible to add metal powders such as aluminum, zinc and copper. More specifically, examples of fillers are silica-based materials such as silica sand, quartz, novaculite and diatomaceous earth: Synthetic amorphous silica: Kaolinite, mica, talc, wollastonite, asbestos, calcium silicate, aluminum silicate Silicates such as: glass powder, glass spheres, hollow glass spheres, glass flakes, glass spheres such as foam glass spheres: boron nitride, boron carbide, aluminum nitride, aluminum carbide, silicon nitride, silicon carbide, titanium boride, nitride Non-oxide inorganic substances such as titanium and titanium carbide: calcium carbonate: metal oxides such as zinc oxide, alumina, magnesia, titanium oxide and beryllium oxide: barium sulfate, molybdenum disulfide, tungsten disulfide, carbon fluoride and other inorganic substances: Metal powder such as aluminum, bronze, lead, stainless steel, zinc: carb Black, coke, graphite, pyrolytic carbon, carbon and the like of the hollow carbon spheres and the like.

These fillers have various shapes such as needle-like shape (including whiskers), granular shape, and scale-like shape, either alone or in 2 pieces.
A mixture of two or more species can be used. Further, it is desirable that the particle size of these fillers is smaller than the film thickness that can be applied at one time. The amount of the filler added is 0.05 parts by weight to 1 part by weight of the acrylic resin and polysilazane in total.
It is in the range of 10 parts by weight, and a particularly preferable amount of addition is 0.2.
The range is 3 to 3 parts by weight. Further, the surface of the filler may be surface-treated by a coupling agent treatment, vapor deposition, plating or the like for use.

The coating composition may contain various pigments, leveling agents, defoaming agents, antistatic agents, ultraviolet absorbers, pH adjusters, dispersants, surface modifiers, plasticizers, and drying accelerators, if necessary. Alternatively, anti-flow agents may be added. The coating composition of the present invention thus prepared is applied once or twice or more on a substrate and then baked to form a coating film.

The base on which the coating composition is applied is not particularly limited and may be any of metal, ceramics, plastics and the like. As a coating means for coating, a usual coating method, that is, dipping, spin coating, roll coating, bar coating, brush coating, spray coating, flow coating or the like is used. Also, sand the base before coating,
When the surface treatment is performed by degreasing, various blasts, etc., the adhesion performance of the coating composition is improved.

After being coated by such a method and sufficiently dried, it is heated and baked. By this firing, polysilazane is crosslinked, condensed, or is oxidized and hydrolyzed depending on the firing atmosphere to be hardened to form a ceramic phase, but at the same time, the acrylic resin is thermally softened to form a Si—O bond or a Si—N bond. It is possible to obtain a dense film in which a ceramic phase mainly composed of and an organic portion composed of an acrylic phase are composited at a fine structure level (compared to a composite material to which an inorganic filler or the like is added).

The firing temperature is preferably a temperature at which polysilazane becomes ceramic and is sufficiently hardened. This is usually 300 ° C. or higher, preferably about 400 ° C. However, since the softening point or decomposition temperature of the acrylic resin is low, it is common to bake at 100 to 300 ° C. Therefore, in order to completely convert polysilazane into a ceramic, a low temperature ceramized type polysilazane such as Japanese Patent Application No. 5-93275 is required, but polysilazane may be selected according to the application. The firing conditions differ depending on the molecular weight and structure of polysilazane. The heating rate is not particularly limited. The firing atmosphere may be oxygen, air, or an inert gas, but the air is more preferable. By firing in air, polysilazane is oxidized or hydrolyzed by water vapor coexisting in air.

As described above, when the polysilazane and the acrylic resin are combined according to the present invention, an inorganic / organic coating hybridized at a fine structure level can be obtained.
In particular, inorganic polysilazane (perhydropolysilazane) is particularly excellent in heat resistance, hardness, and adhesion, and the combination with acrylic resin, which is characterized by its elongation, is a well-balanced composite system that compensates each other's disadvantages. Provides properties that exceed those of composite coatings.

This is perhydropolysilazane and acrylic
When using a combination of resin, glass filler, etc.
Soluble in xylene, unlike so-called composite resin
Homogeneous perhydropolysilazane and acrylic resin
Since the starting point is the state of dissolution in
Amorphous SiO at the level of fine structure₂ / Si₃ N _Four 
What is expected to be a composite of acrylic resin and acrylic resin
And the ceramicization of perhydropolysilazane
When shrinking, the acrylic resin softens and follows,
It is thought that it is easy to obtain a dense film without holes
To be

Further, according to the present invention, it is easy to control the balance between the inorganic substance (ceramics) and the organic substance (acrylic resin). As mentioned above, since polysilazane-based ceramics and acrylic resin are compounded at a uniform and fine structure level, a wide range of ratios of inorganic and organic substances can be selected, and heat resistance and hardness are emphasized. It is possible to realize excellent characteristics in a wide range including those with an emphasis on flexibility.

Furthermore, since polysilazane becomes an amorphous ceramic having a low coefficient of thermal expansion after firing, the film thickness limit is low as a single substance due to the problem of matching with a metal substrate, but the acrylic resin has a high coefficient of thermal expansion. It is possible to match with various substrates, and therefore, with the coating composition of the present invention, a thick film of 10 to 100 μm can be easily applied. The characteristics of the amorphous ceramics after firing the polysilazane and the acrylic resin are compared and summarized as follows.

Polysilazane (amorphous ceramic after firing) Acrylic resin ─────────────────────────────────── Hardness High Low Flexibility (Extension) Extremely Low High Heat Resistance Extremely High Low Thermal Expansion Very Low High Adhesion Very High Poor Ceramic Yield Very High-Shrinkage Relatively Low-Thermal Properties Heat Curing Thermal Softening, Melting, Heat curing

[0039]

【Example】

Example 1 Acrylic resin BR-71 manufactured by Mitsubishi Rayon was dissolved in xylene to prepare a 10 wt% solution. Next, a 20 wt% xylene solution of perhydropolysilazane PHPS-1 manufactured by Tonen, and B
A 10 wt% xylene solution of R-71 was added to PHPS: BR
71 = 6: 4 (wt) mixed with a stirrer,
A colorless and transparent coating liquid was obtained. SUS30 degreased with 150 × 50 × 0.4 mm ^t using this coating liquid
4 and Cu plates were applied by flow coating and dried at room temperature for 10 minutes. Then, it was baked at 300 ° C. for 1 hour (heated at 10 ° C./minute) to obtain a colorless and transparent ceramic / acrylic resin coating film having a thickness of about 2 μm. The hardness of this coating film was> 9H (SUS304 substrate). In addition, 30 × 30 × 1.1 mm ^t quartz glass was spin-coated (2000 rpm × 20 sec.
), The spectrophotometric value of the coating film (thickness 1 μm) baked at 300 ° C. for 1 hour was measured, and the visible light transmittance at 500 nm was 96%. Next, when a bending test was performed, both the SUS304 substrate and the Cu substrate passed 5T. Example 2 A ceramic / acrylic resin-based colorless transparent film was applied in the same manner as in Example 1 except that the following conditions were changed. PHPS: BR71 = 5: 5 (wt) The evaluation results were as follows. Hardness: 9H Visible light transmittance (@ 500nm); 95% Bendability: 1T Pass Example 3 40 wt% xylene solution of PHPS-1 and 1 of BR-71
PHPS: BR71 = 6: 4 with 5 wt% xylene solution
After adjusting the coating liquid so that it becomes (wt), SU
It was applied by flow coating to the S304 substrate. When baked at 300 ° C. for 1 hour, a ceramic / acrylic resin-based colorless transparent film having a film thickness of 10 μm and a hardness of> 9H was obtained. Examples 4 to 9 and Comparative Example 0.5 wt% (based on 100 polysilazane) Pd acetate was added to PHPS-1. 20 wt% xylene solution of low temperature ceramic type polysilazane and 10 wt% of BR80
% Xylene solution was mixed in the following proportions. When the above coating liquid was applied to a SUS304 substrate in the same manner as in Example 1 and baked at 200 ° C. for 1 h, a colorless transparent film having a film thickness of 2 to 3 μm was obtained in each sample. When the hardness of these coating films was measured, the following results were obtained. Hardness ─────────────────── Example 4> 9H Example 5> 9H Example 6> 9H Example 7> 9H Example 8 9H Example 9 9H Comparison Example 4H

[0040]

According to the present invention, by making the polysilazane resin and the acrylic resin compatible with each other, a transparent coating film can be obtained in which the characteristics of the polysilazane are utilized without deteriorating the characteristics of the polysilazane. . As a result, heat resistance, hardness,
An inorganic / organic hybrid film having excellent adhesion, flexibility, film thickness limit, and price can be easily obtained.

Claims (1)

[Claims] 1. Mainly represented by the general formula (I): (However, 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 in which the group directly bonded to silicon is carbon, an alkylsilyl group, an alkylamino group, and an alkoxy group. However, at least one of R ¹ , R ² and R ³ is a hydrogen atom. The coating composition is a solution in which a polysilazane having a main skeleton composed of units represented by the formula (1) and having a number average molecular weight of 100 to 50,000 and an acrylic resin are dissolved.