JP2012184378A - Polysilazane coating liquid contained in spray type airtight container and method for coating polysilazane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polysilazane coating liquid contained in a spray type airtight container excellent in storage stability, and a method for coating polysilazane.SOLUTION: This polysilazane coating liquid contained in a spray type airtight container is obtained by filling a polysilazane-containing solution into the spray type airtight container filled with compressed gas or liquefied gas, where a dehydrating agent is made coexist in the spray type airtight container. The dehydrating agent is preferably one or the other of a fired mixture of synthetic zeolite and a clay mineral, or a fired mixture of sodium aluminosilicate and a clay mineral.

Description

  The present invention relates to a polysilazane coating solution containing a spray-type sealed container and a polysilazane coating method.

  Polysilazane coating using polysilazane, which is a precursor polymer of silica, silicon nitride, and silicon oxynitride, exhibits excellent adhesion to various materials such as coating film, rubber, resin, and aluminum. Since it has the property of curing, it has attracted attention as a technology that can be applied to a wide range of applications.

  Conventionally, as a method for applying such polysilazane, methods such as dipping, roll coating, bar coating, brush coating, spray coating, and flow coating have been employed.

  In these coating methods, polysilazane is usually used as a solution diluted with an organic solvent. However, since polysilazane itself easily oxidizes and hydrolyzes in an oxidizing atmosphere such as air, it must be handled until coating. It is necessary to pay attention to.

  In consideration of such properties of polysilazane, spray coating is relatively easy to handle and coating properties are good in the above coating method, and a good film is easily obtained. For example, Patent Document 1 discloses a polysilazane-containing solution and Disclosed is a polysilazane spray coating apparatus comprising a sealed container filled with compressed nitrogen gas, and a polysilazane-containing solution spraying means provided from the bottom to the top of the container. Aerosol spray cans for ordinary paints without cumbersome operations such as transfer of solution in non-oxidizing atmosphere, setting of device, expelling air from solution flow path, removal of solution in solution flow path Similarly, it is described that a simple and economical spray coating is possible.

  However, the technique of Patent Document 1 and other conventional techniques have a problem that the polysilazane is not stable in the spray coating apparatus, and the polysilazane is gradually solidified in the spray coating apparatus and cannot be used. .

JP-A-11-57743

  An object of the present invention is to provide a polysilazane coating solution and a polysilazane coating method in a jet type airtight container which solves the above problems and is excellent in storage stability.

  The polysilazane coating liquid containing a jet-type sealed container of the present invention made to solve the above problems is a polysilazane coating liquid containing a jet-type sealed container filled with a polysilazane-containing solution in a jet-type sealed container filled with a compressed gas or a liquefied gas. In this case, a dehydrating agent is allowed to coexist in the jet-type sealed container.

  The invention according to claim 2 is the polysilazane coating solution in a jet type airtight container according to claim 1, wherein the dehydrating agent is at least any one of a calcined mixture of synthetic zeolite and a viscous mineral, or a calcined mixture of sodium aluminosilicate and a viscous mineral. It is characterized by being.

  The polysilazane coating method according to claim 3 is characterized in that the polysilazane coating solution containing the spray type airtight container according to claim 1 or 2 is sprayed onto a substrate.

  In other conventional techniques, polysilazane gradually solidifies in a spray coating apparatus and cannot be used. The solidification of the polysilazane is caused by the decomposition of polysilazane into silicon dioxide, ammonia and hydrogen from the water remaining in the spray coating apparatus. In a sealed container such as an aerosol can, it is a well-known technique to simply replace moisture with air by compressed nitrogen gas or to discharge moisture with compressed nitrogen gas. Solidification of polysilazane in the spray coating apparatus, which could not be avoided, can be avoided by the coexistence of a dehydrating agent in an aerosol spray can filled with compressed gas or liquefied gas.

  Preferred embodiments of the present invention are shown below.

  The polysilazane coating solution containing a jet-type airtight container of the present invention is obtained by sealingly storing polysilazane in an aerosol spray can filled with a compressed gas or a liquefied gas, and allowing a dehydrating agent to coexist in the spray can.

Polysilazane is an inorganic polymer soluble in an organic solvent having-(SiH ₂ NH)-as a basic unit, and its official name is called perhydropolysilazane (PHPS = polysilazane whose side chains are all hydrogen). By using an organic solvent solution of PHPS as a coating solution and baking in the air or in an atmosphere containing water vapor, it reacts with moisture and oxygen, and a dense high-purity silica (amorphous SiO ₂ ) film is obtained at about 450 ° C. Utilizing this characteristic, it was put to practical use as a coating type high-purity silica coating material. Thereafter, dehydrogenation and the addition of a Pd compound as an acid catalyst allowed the conversion temperature to silica (the temperature for ceramicization) to be reduced to about 250 ° C. In general, the lower the firing temperature for making it into quartz, the easier it is to handle and process, and it can be applied to a wide range of substrates. Therefore, various techniques for lowering the firing temperature have been developed. Currently, a technique has been developed that can be converted into a high-purity silica film at room temperature by adding a small amount of an amine-based catalyst that promotes the reaction with moisture. Among these, the present invention is a polysilazane coating solution containing a jet type airtight container suitable for a room temperature silica conversion type polysilazane.

The room temperature silica conversion type polysilazane is rapidly converted into dense silica (SiO ₂ ) at room temperature by the reaction of the following [Chemical Formula 1].

  Polysilazane itself is a liquid or solid having a different viscosity depending on the molecular weight and molecular structure. Therefore, in the case of a low-viscosity liquid, it may be filled in an aerosol spray can as it is, but particularly in the case of a high-viscosity liquid. In order to control coatability and coating thickness, dilute with various organic solvents such as hydrocarbon solvents such as xylene (o- or m-xylene), cyclohexane and cyclohexene; ether solvents such as dibutyl ether. It is preferably used as a solution. In the case of a solid, it cannot be applied as it is, so it must be diluted with an organic solvent and used as a solution. Perhydropolysilazane is a completely inorganic polymer composed only of <Si-H, NH, Si-N> bonds, and it reacts with a substance with OH (hydroxyl group) and is hydrolyzed. When used, it is preferable to use a high-boiling aromatic solvent such as xylene or mineral turpentine, and it is preferable to select an optimum solvent according to the matching with the base material, application, purpose, construction environment, etc. .

  Although it is a well-known technique to use the inside of an aerosol spray can in which compressed gas or liquefied gas is enclosed for the purpose of eliminating moisture in the aerosol spray can, aerosol spraying is only performed by filling compressed gas or liquefied gas. The moisture contained in the can and the moisture contained in the compressed nitrogen gas cannot be completely removed. Conventionally, this caused the polysilazane to undergo a chemical reaction and decompose into silicon dioxide, ammonia, and hydrogen. There was a problem of solidifying inside. In the present invention, the problem can be avoided by a configuration in which a dehydrating agent is allowed to coexist in an aerosol spray can filled with compressed gas or liquefied gas.

  As the liquefied gas, known dimethyl ether, LP gas or the like can be used alone or in combination, but dimethyl ether is particularly preferable from the viewpoint of the solubility and atomization of polysilazane. The amount of the propellant used is preferably 0.1 to 99.9% by volume with respect to polysilazane.

  It is also possible to enclose a compressed gas such as nitrogen gas, carbon dioxide gas, argon gas or helium gas together with or in place of the liquefied gas.

  As the dehydrating agent, it is preferable to use at least one of a calcined mixture of synthetic zeolite and a viscous mineral, or a calcined mixture of sodium aluminosilicate and a viscous mineral. Since these dehydrating agents have the property of chemically adsorbing water molecules, which are polar molecules, by metal cations, they effectively suppress the phenomenon of polysilazane's chemical decomposition triggered by moisture mixed in the spray can. However, it is possible to effectively avoid the problem of being hardened in a short period of time and becoming unusable.

  The amount of the dehydrating agent used is preferably 1 to 20% by mass with respect to the mass of polysilazane. If it is less than 1% by mass, the dehydration effect cannot be exhibited, which is not preferable. On the other hand, since the dehydration effect is almost saturated at 20% by mass, use exceeding 20% by mass is not preferable.

  When filling each of the above components into an aerosol container, it is desirable to work so that moisture does not enter. It is desirable to control the amount of water to be about 750 PPM or less, preferably 500 PPM or less. In addition to the above-described blending of the dehydrating agent, the moisture mixing can be controlled by previously dehydrating each raw material in the paint.

  According to the polysilazane coating solution containing the above-mentioned spray-type sealed container of the present invention, a colorless transparent tough coating film excellent in durability, weather resistance, hydrophilicity and adhesion can be obtained by a simple means of spraying a spray can. Can be formed. For this reason, the polysilazane coating solution in a spray-type sealed container is used for antifouling coatings (protective coatings, hydrophilic coatings), anticorrosion coatings, heat resistant coatings, hard coatings, etc. It can be suitably used in a wide range of applications such as coating. For example, by applying a polysilazane coating solution containing a jet-type airtight container of the present invention as a primer coat layer on the surface of the base material and laminating a fluororesin film on the surface, an extremely stable and highly adhesive fluororesin coating is formed. It becomes possible.

  In addition, the polysilazane coating solution in the above-mentioned airtight sealed container of the present invention is excellent in storage stability in an aerosol spray can, so after use of the required amount, the untreated polysilazane solution remaining in the spray can is cured. Can be used repeatedly without causing

  Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. However, the present invention is not limited only to the following examples.

Example 1
A primer coat “PC-C” of “Shinshowa Co., Ltd.” was used as the polysilazane solution, and a molecular sieve (4AXH-5 4 × 8 manufactured by Union Showa Co., Ltd.) was used as the dehydrating agent. The amount of the dehydrating agent added was 2% by weight with respect to the polysilazane solution. These were filled in an aerosol spray can filled with liquefied gas (dimethyl ether having a volume ratio of 50% in the container) to prepare a polysilazane coating solution containing a jet type airtight container of Example 1.

Here, the molecular sieve is a synthetic zeolite that focuses on the unique adsorption characteristics of naturally produced zeolite. The molecular sieve is composed of a hydrous metal salt of synthetic crystal aluminosilicate. When the crystal water of this metal salt is heated and desorbed and removed, a cavity remains in the trace of the crystal water removed, and adsorbed molecules are placed on the inner wall of the cavity. It has a dehydrating function by adsorption. In order for these adsorbed molecules to enter this cavity, they must pass through uniform pores connected from the surface, but molecular sieves have very uniform pores, so molecular level Only molecules that act as a sieve and can pass through it reach the inner wall of the cavity and are adsorbed. The molecular sieve is a crystalline zeolite, the general formula of which is shown by the following chemical formula, and has the property of strongly adsorbing water molecules, which are polar molecules, by the following metal cations.

The molecular sieve (4AXH-5 4 × 8 manufactured by Union Showa Co., Ltd.) used in this example is represented by the following chemical formula.

(Example 2)
The primer coat “PC-C” of “Shinshowa Co., Ltd.” was used as the polysilazane solution, and quicklime was used as the dehydrating agent. In addition, the addition amount of this quicklime was 1 weight with respect to the polysilazane solution. These were filled in an aerosol spray can filled with compressed gas (20% nitrogen gas in the container volume ratio) to prepare a polysilazane coating solution containing a jet-type sealed container of Example 2.

(Example 3)
As a polysilazane solution, a primer coat “PC-B” of “Shinshowa Co., Ltd.” was used, and a commercially available silica gel was used as a dehydrating agent. In addition, the addition amount of this silica gel was 5 weight% with respect to the polysilazane solution. These were filled in an aerosol spray can filled with compressed gas (60% LPG in the volume ratio in the container) to prepare a polysilazane coating solution containing a jet type airtight container of Example 3.

  In each of Examples 1, 2, and 3, the polysilazane solution in the aerosol can was stably stored without solidifying in the aerosol can for at least 2 months (in Examples 1 and 3 or more). Moreover, even after the lapse of the period, the polysilazane in the aerosol can is maintained without changing the chemical activity, and after the lapse of the period, the glass substrate (Examples 1 and 3) or stainless steel As a result of performing polysilazane coating on the plate (Example 2) and evaluating the hardness of the formed film, Examples 1 and 3 showed a pencil hardness of 9H or higher, and Example 2 had a pencil hardness of 8H or higher. Hardness was shown and a strong film was formed in all cases.

(Comparative Examples 1-3)
Each of the polysilazane coating liquids in Comparative Examples 1 to 3 was prepared under the same conditions as in Examples 1 to 3 except that no dehydrating agent was added.

  In any of Comparative Examples 1 to 3, the polysilazane solution in the aerosol can solidified within one week, and injection was impossible.

The invention according to claim 2 is the polysilazane coating solution in the jet-type sealed container according to claim 1, wherein the dehydrating agent is at least one of a calcined mixture of synthetic zeolite and clay mineral , or a calcined mixture of sodium aluminosilicate and clay mineral. It is characterized by being.

As the dehydrating agent, it is preferable to use at least one of a calcined mixture of synthetic zeolite and clay mineral or a calcined mixture of sodium aluminosilicate and clay mineral . Since these dehydrating agents have the property of chemically adsorbing water molecules, which are polar molecules, by metal cations, they effectively suppress the phenomenon of polysilazane's chemical decomposition triggered by moisture mixed in the spray can. However, it is possible to effectively avoid the problem of being hardened in a short period of time and becoming unusable.

Claims (3)

A polysilazane coating solution containing an injection-type sealed container filled with a polysilazane-containing solution in an injection-type sealed container filled with compressed gas or liquefied gas,
A polysilazane coating solution containing an airtight container, wherein a dehydrating agent is allowed to coexist in the airtight container.   2. The polysilazane coating solution in a jet-type sealed container according to claim 1, wherein the dehydrating agent is at least one of a sintered mixture of synthetic zeolite and a viscous mineral, or a sintered mixture of sodium aluminosilicate and a viscous mineral.   A polysilazane coating method comprising spraying a polysilazane coating solution in a jet-type airtight container according to claim 1 or 2 onto a substrate.