JP2000053920A - Polysilazane-including composition for forming coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polysilazane-including composition for forming coating films capable of being cured at an ordinary temperature in the air without baking it and capable of performing field coating such as brush coating, spray one, or the like. SOLUTION: This polysilazane-including composition for forming coating films is prepared by formulating a perhydropolysilazane having 100-50,000 number average molecular weight and having no organic group, an oxidation catalyst such as palladium propionate and, optionally, photocatalyst powder such as titanium dioxide with an organic solvent (e.g. m-xylene) having no OH group. The composition can be cured while merely left to stand at an ordinary temperature in the air by making the concentration of perhydropolysilazane 0.1-5 wt.% in terms of the concentration of solid content and can simply be applied to the surface of an object by field coating such as brush coating, spray one, or the like in the air. It is pref. to add photocatalyst powder in the application.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for forming a coating film containing polysilazane, and in particular, forms a tough coating film on a building wall or the like by in-situ coating such as brush coating or spray coating. And a polysilazane-containing coating composition.

[0002]

2. Description of the Related Art
Examples of the composition for forming a polysilazane-containing coating film include a coating composition containing a polymetallosilazane obtained by heating and reacting a polysilazane and a metal alkoxide (JP-A-1-221466), and a heat reaction between a polysilazane and a silicon alkoxide. Coating composition containing a silicon alkoxide-added polymetallosilazane obtained by the reaction (Japanese Patent Application Laid-Open No. Hei 5-23827), and coating containing a glycidol-added polymetalosilazane obtained by heating and reacting polysilazane and glycidol. Composition (JP-A-6-122852), coating composition containing alcohol-added polymetallosilazane obtained by heating and reacting polysilazane and alcohol (JP-A-6-240208), polysilazane and various metal carboxylic acids Salt Coating composition comprising a reaction product obtained by response (JP-A 6-299118
No.), polysilazane and the general formula (CH ₃ COCHCOCH)
_{3) n} M [M is an n-valent metal] coating compositions comprising acetylacetonato complex added polysilazane obtained by heating the reaction acetylacetonato complexes of various metal represented by (JP-A-6-306329 ) Is disclosed.

[0003] These polysilazane-containing coating compositions are excellent in heat resistance, abrasion resistance and chemical resistance, can form a coating having a high surface hardness, and can be fired at a relatively lower temperature. In particular, those containing perhydropolysilazane have the advantage that they can be cured at room temperature without firing.

However, in the case of a coating composition in which an oxidation catalyst such as a metal carboxylate or an acetylacetonate complex is blended with perhydropolysilazane, the composition can be cured at room temperature without sintering as described above. Is very high, so if painting on site, that is, brushing or spraying at room temperature and air atmosphere, reacts violently with moisture and oxygen in the atmosphere, and in the case of spray coating, the spray gun body However, there was a problem that clogging occurred in a short time, and as a result, the painting operation could not be performed. In this case, it is conceivable to use a special coating system that is devised so as not to be affected by moisture or oxygen.However, using such a special coating system for on-site painting at a building site is expensive. It was not realistic.

Accordingly, a first object of the present invention is to solve the above-mentioned problems by curing at room temperature and in the air without firing, and without using a special coating system. It is an object of the present invention to provide a composition for forming a perhydropolysilazane-containing coating film which can be applied on site such as brush coating or spray coating.

On the other hand, in recent years, semiconductor fine particles such as titanium oxide which act as a photofunctional catalyst (hereinafter referred to as "photocatalytic particles").
And various uses such as sterilization, deodorization, declouding, and washing of these various semiconductor fine particles have been disclosed. For example, when titanium oxide is attached to the surface of a soundproof wall of a road, the outer wall of a building, a telephone box, or the like, a self-cleaning function can be given to these surfaces.

[0007] As a method of attaching such photocatalyst particles to the target surface, Japanese Patent Application Laid-Open No. 9-164091 discloses a method of supporting the photocatalyst particles on the target surface using an organic binder, And a method in which photocatalyst particles are coated on a heated plastic target surface and pressed with a mold or the like to embed the photocatalyst particles.

However, the method using an organic binder is as follows.
Due to the photocatalytic action, the organic binder around the photocatalyst particles is decomposed and loses the binder function, so that the photocatalyst falls off the substrate, so that the life is short. Also, 6
It was practically impossible to apply the method of baking at around 00 ° C. to the wall surface of the building, and the method of embedding the photocatalyst particles also required that the surface of the object be heated in advance. Construction on the wall of the object was practically difficult.

Accordingly, a second object of the present invention is to solve the above-mentioned problems by allowing photocatalyst particles to adhere to the surface of an object without using an organic binder and without firing. An object of the present invention is to provide a composition for forming a polysilazane-containing coating film, which can form a tough and long-life photocatalytically active coating on the wall surface of an object by in-situ coating.

[0010]

Means for Solving the Problems In order to achieve this object,
The present inventors first tried spray coating in the atmosphere by diluting a coating film forming composition obtained by blending perhydropolysilazane and an oxidation catalyst with an organic solvent to a limit that can be assumed as a normal coating material. The spray gun body was clogged. After that, I tried it by changing the composition such as adding various additives, but I was able to cure at room temperature and air, and I could not obtain the result that I could easily perform on-site painting in the air Was. However, a composition that was accidentally thinned to the extent that it could not be expected as a normal paint was completed, and as a result of trying this, it was incredible that it could be cured at room temperature and in the air, and that it could be easily applied in the field in the air Have found that you can do that. The present invention has been made based on such findings.

That is, the invention of claim 1 is a composition for forming a polysilazane-containing coating film obtained by blending polysilazane and an oxidation catalyst in an organic solvent having no OH group, wherein the polysilazane does not have an organic group. 3. A composition for forming a polysilazane-containing coating film, which is perhydropolysilazane (number average molecular weight: 100 to 50,000) and is blended as a solid content of 0.1 to 5% by weight. The present invention is a composition for forming a polysilazane-containing coating film in which photocatalyst particles are added to the composition of the composition for forming a polysilazane-containing coating film.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

The composition for forming a polysilazane-containing coating film of the present invention is prepared by blending “polysilazane” and “oxidation catalyst” with “solvent” to prepare a polysilazane solution, and further diluting the solution with “solvent”. can do. Hereinafter, the production method will be described, but the production method of the polysilazane-containing coating film forming composition of the present invention is not limited thereto,
It is also possible to dilute to a predetermined concentration at once without using the "solvent".

The "polysilazane" used in the present invention is a perhydropolysilazane in which R ¹ , R ² and R ³ are all hydrogen atoms in the following chemical formula showing polysilazane. Since perhydropolysilazane having no organic group is all H bonded to Si or N,
Not only does steric hindrance not hinder the reaction, but it is not oxidized or decomposed unlike organic groups. Therefore, at room temperature
Oxidation or hydrolysis due to water vapor in the air proceeds and cures just by holding in the air, and since it functions as a completely inorganic binder, it can form a photocatalytically active film with a long life without being decomposed by photocatalysis. it can. The molecular weight of perhydropolysilazane is not particularly limited, and those having a number average molecular weight of 100 to 50,000 can be used.

[0015]

Embedded image

The "oxidation catalyst" used in the present invention includes:
JP-A-6-299118 discloses in section [0024].
Metal carboxylate, specifically represented by the general formula (RCO
O)_nM [M is an n-valent metal].
For example, nickel, titanium, platinum, rhodium, Kovar
, Iron, ruthenium, osmium, palladium, iridium
At least selected from the group of
Japanese Patent Application Laid-Open No. Hei 6-306329
Acetyl of various metals disclosed in column [0023]
Acetonato complexes, specifically acetylacetone (2,4
-Pentadione) is anion generated by acid dissociation into gold
A complex coordinated to a genus atom and represented by the general formula (CH _ThreeCOCH
COCH_Three)_nM [M is an n-valent metal]
As [M], for example, nickel, platinum, palladium, aluminum
List those containing minium, rhodium, etc.
Can be. However, it is not limited to these.
The amount of the “oxidation catalyst” depends on the oxidation catalyst / polysilazane polymerization.
The ratio is 0.000001 to 2, preferably 0.001 to
1, more preferably 0.01 to 0.5.
I can.

The "solvent" used in the present invention includes aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbon solvents, halogenated hydrocarbons, aliphatic ethers, alicyclic ethers, and aromatic hydrocarbons. An organic solvent such as amines having no OH group, for example, benzene, toluene, xylene, methylene chloride, chloroform, n-hexane, ethyl ether, tetrahydrofuran, pyridine, methylpyridine and the like is used. The reason why the organic solvent having no OH group is limited in the present invention is to prevent the reaction between the solvent and polysilazane.

As the "solvent" used in the present invention, the organic solvents exemplified as the solvent, that is, organic solvents having no OH group can be suitably used.

The composition for forming a polysilazane-containing coating film of the present invention is prepared by blending the above-mentioned "polysilazane" and the above-mentioned "oxidation catalyst" with the above-mentioned "solvent" to prepare a polysilazane solution. At this time, the mixing ratio of “perhydropolysilazane” is 0.1 to 5% by weight, preferably 0.1 to 5% by weight, as a solid concentration in the solvent or the solvent. Adjust so as to contain 含 ま 3% by weight. If it exceeds 5% by weight, on-site coating in the atmosphere becomes impossible immediately, and if it is less than 0.1% by weight, the function as a binder is extremely reduced. [0031] column of JP-A-6-299118,
The column [0031] of JP-A-6-306329 states that a good result can be obtained by adjusting the solvent concentration in the range of 0 to 90% by weight. In the composition, the concentration of the solid component is usually less than 10% considering the thickness of the coating film. However, in the present invention, by adjusting the content to 5% by weight or less, the effect unique to the present invention was successfully obtained.

Further, a photocatalytic action can be imparted to the coating film by blending “photocatalytic particles” with the above composition.

The “photocatalyst particles” include titanium oxide (T
iO ₂ ), iron oxide (Fe ₂ O ₃ ), tungsten oxide (WO ₁ ), zinc oxide (ZnO), zinc sulfide (Zn
S), cadmium sulfide (CdS), strontium titanate (SrTiO ₂ ), molybdenum sulfide (MoS ₂ ), or other conventionally known fine particles of a photocatalyst can be used.

The "photocatalyst particles" can be directly mixed with the above-mentioned polysilazane solution. However, in order to disperse the photocatalyst particles more uniformly, various organic materials such as m-xylene and o-xylene are separately provided from the polysilazane solution. A dispersant is mixed with a solvent, and photocatalyst particles are mixed therein to prepare a fine particle dispersion, and the fine particle dispersion and the polysilazane solution are mixed to prepare a polysilazane-containing coating film-forming composition. . Here, as the “dispersant”, for example, Solsperse # 3000, # 9000, # 170 manufactured by Zeneca Corporation
00, preferably # 9000 and # 1700
0 is used. The amount of the dispersant is preferably 5 to 50% by weight, and particularly preferably 10 to 30% by weight, based on the photocatalyst particles.

Hereinafter, as an example of a method of applying the composition for forming a polysilazane-containing coating film of the present invention, a method of applying the composition to an exterior wall of a building will be described.

First, although necessary, prior to coating the polysilazane, the surface to be coated is washed using a high-pressure washing machine or the like, and then the surface to be coated is completely dried and cured. dry.

Then, the composition for forming a polysilazane-containing coating film prepared as described above is applied to an outer wall surface of a building by in-situ coating such as spray coating. As the spraying device, it is not necessary to use a special coating system designed so as not to be particularly affected by moisture or oxygen, but the coating efficiency is 65% or more and the atomizing air pressure is 0.1 psi to 10 psi.
(0.007 to 0.7 kg / cm ² ) Electrostatic coating machine or high volume low pressure
If a spray is used, clogging can be prevented and coating can be performed more uniformly.

At this time, the amount of the composition for forming a polysilazane-containing coating film is preferably applied to a thickness of 0.01 μm to 1 μm particularly when photocatalyst particles are blended. Speaking of coating thickness for architectural use, usually 30μm ~ 50μ
m, the thickness is usually difficult to assume,
By forming a coating thickness of 0.01 μm to 1 μm,
Photocatalyst particles having a particle size of 0.01 μm to 1 μm can be reliably scattered on the surface of the coating film and can be surely adhered to the outer wall surface. The surface to be painted is made of various metals
The material such as concrete, glass or various plastics is not particularly limited.

The thus-coated polysilazane-containing coating film-forming composition is allowed to stand in air at room temperature for 1 to 3 days, whereby the perhydropolysilazane in the composition is accelerated by an oxidation catalyst, and is cured. A Si—O-based or Si—N—O-based ceramic having a photocatalyst dispersed on the surface, that is, a complete inorganic dense and tough film is formed. This film is excellent in corrosion resistance, heat resistance, and abrasion resistance, has high adhesion to the target surface, and is not completely decomposed or deteriorated by a photocatalyst because the film is completely inorganic.

Further, by dispersing the photocatalyst on the surface, the photocatalyst receives light of a wavelength having energy equal to or greater than the band cap, for example, light of sunlight or an electric lamp, and has a strong reducing action on the surface by photoexcitation. Electrons and holes having a strong oxidizing action are generated, and a self-cleaning function of decomposing and removing contaminants such as organic substances and oils adhered to the surface by the redox action is exhibited. In addition, Japanese Patent No. 2756474 discloses the idea that the surface of a base material is made hydrophilic by chemically adsorbing the surface in the form of a hydroxyl group (OH ⁻ ) by the photocatalytic action of a photocatalyst to impart a self-cleaning function to the surface. For example, in the case of a coating composition obtained by dispersing photocatalyst particles in a silicone coating, an organic group bonded to a silicon atom of a silicone molecule is replaced with a hydroxyl group by a photocatalytic action, whereby the target surface (in other words, the surface of the silicone coating as a binder). It is to make itself hydrophilic. In contrast, the present invention uses perhydropolysilazane having no organic group, and uses a solvent and a solvent having no OH group as a solvent, so that the surface of the coating itself is hydrophilized by photocatalysis. Patent No. 2756474
It is completely different from the idea of the issue. Incidentally, Japanese Patent No. 2756474 also discloses the use of polysilazane, but is limited to an organopolysilazane compound having an organic group. From this point, the difference between the two is clear.

[0029]

Embodiments of the present invention will be described below.

(1) Preparation of Polysilazane-Containing Film-Forming Composition Perhydropolysilazane (organic polysilazane) having no organic group and palladium propionate (C ₂ H ₅ COO)
Pd) was dissolved in an m-xylene solution to prepare a 20% by weight polysilazane solution, which was further diluted with an m-xylene solution to form a coating composition for each of the formulations (formulations 1 to 4) in Table 1 below. Was manufactured.

[0031]

[Table 1]

(2) Brush Coating 100 g of the composition for forming a coating film of Formulations 1 to 4 was weighed in a polycup container, and the coating amount was adjusted to 10 using a flat brush on a metal plate.
An operation of coating at a rate of ２０20 g / m ² was performed. The work was performed in an environment of 20 ° C. and 65%. At this time, the time required for the material to react with oxygen and moisture in the air and hinder the brushing work was defined as the work limit time, and the test results are shown in Table 2. Indicated.

[0033]

[Table 2]

As a result, with respect to Formulations 1 and 2, gelation had already begun in the container before the working time of 10 or 20 minutes had elapsed, and further coating work could not be performed. On the other hand, with regard to Formulations 3 and 4, no gelling of the material occurred until the end of the coating operation (about 30 minutes), and a normal coating operation without coating unevenness could be performed.

(3) Roller Brush Coating 100 g of the composition for forming a coating film of the above-mentioned Formulations 1 to 4 is weighed in a polycup container, and is applied to a metal plate using a roller brush at an application rate of 10 to ²⁰ g / m ^2. Did the work.
The work was carried out in an environment of 20 ° C. and 65%. At this time, the time required for the material to react with oxygen and moisture in the air and hinder the brushing work was defined as a work limit time, and the test results are shown in Table 3. Indicated.

[0036]

[Table 3]

As a result, with respect to Formulations 1 and 2, gelation had already begun in the container by the time the work time passed for 10 or 20 minutes, and further coating work could not be performed. On the other hand, with regard to Formulations 3 and 4, no gelling of the material occurred until the end of the coating operation (about 30 minutes), and a normal coating operation without coating unevenness could be performed.

(4) Spray coating using an air spray gun The coating operation is performed by repeating the steps of spoon-coating the composition for forming a coating film of each of the above Formulations 1 to 4 with an air spray gun for 1 minute and then stopping for 30 seconds. Was done. The setting and coating conditions of the used air spray gun are as follows. Nozzle diameter: 0.6 mm Blowing air pressure: 3.0 kg / cm ² Air consumption: 30 l / min Blowing distance: 200 mm Paint ejection amount: 30 ml / min Moving speed: about 20 cm / min Pattern opening: 100 mm Work 20 ℃, 65% environment, at this time, the number of times the material reacts with oxygen and moisture in the air and hinders the painting work is measured, and this is used as a guide to the paintable time,
The test results are shown in Table 4.

[0039]

[Table 4]

As a result, with regard to Formulations 1 and 2, the spraying of the material became worse due to the clogging of the nozzle after coating and stopping 2 to 5 times, and the liquid could not be sprayed from the tip of the gun. It became. On the other hand, for Formulations 3 and 4, the state at the start of spraying was maintained until all of the prepared compositions disappeared (about 15 minutes).

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor, Kanji Kobayashi Tokyo Metropolitan Government, Tokyo, Japan PC04 PC08

Claims (2)

[Claims] 1. A composition for forming a polysilazane-containing coating film obtained by mixing a polysilazane and an oxidation catalyst in an organic solvent having no OH group, wherein the polysilazane is a perhydropolysilazane having no organic group (number-average molecular weight). 100 to 50,000) and 0.1 to 5% by weight as a solid content concentration. 2. The composition for forming a polysilazane-containing coating film according to claim 1, comprising photocatalyst particles.