JPH08281199A - Coating of polysilazane solution - Google Patents

Abstract

PURPOSE: To easily adjust a coating amt. and to minimize a residual liquid amt. by bringing an infiltrative member infiltrated with a polysilazane soln. into contact with an article to be coated and relatively moving both of them. CONSTITUTION: When a polysilazane soln. 13 is applied to an article 15 to be coated, an infiltrative member 10 infiltrated with the polysilazane soln. 13 is brought into contact with the article 15 to be coated and both of the infiltrative member 10 and the article 15 to be coated are relatively moved. At this time, for example, the infiltrative member 10 composed of a rotary roller 12 covered with a felt material 11 is used and, at first, a definite amt. of the polysilazane soln. 13 is preliminarily infiltrated into the felt material 11 and the infiltrative member 10 is brought into contact with the article 15 to be coated under predetermined pressure and the member 10 is rotated. At this time, the polysilazane soln. 13 is controlled so as to be dripped and supplied from a supply means 14 in the ratio corresponding to the rotational speed (coating speed) at this time. By this constitution, a uniform polysilazane coating film 16 having desired thickness is continuously obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for coating a polysilazane solution.

[0002]

_2. Description of the Related Art A method has been developed for coating a surface of a substrate with ceramics which substantially consists of a SiO ₂ film. For example, in Japanese Patent Application No. 5-318188 by the present applicant, a coating composition containing a specific polysilazane is applied, heat-treated, and then exposed to a steam atmosphere, and / or
Alternatively, a method is disclosed in which a plastic film is coated with a SiO ₂ ceramic at a low temperature of 150 ° C. or lower by performing a step of immersing in an aqueous solution containing an acid catalyst or a base catalyst. Also, Japanese Patent Application No. 6-236881 filed by the applicant of the present application discloses a method of forming a film of polysilazane on a substrate and then contacting it with an aqueous solution of silicate ester so that the SiO ₂ ceramics can be coated even at room temperature. Has been done.

In these methods, it is necessary to apply a polysilazane solution to a substrate, but as a method for continuously applying a polysilazane solution to a long-sized object having a large area, a gravure roll coater and a reverse coater are used. A method using a roll coater, a natural roll coater, etc. is known. The coating amount in these devices is adjusted by adjusting the gap between the doctor roll and the coating roll and the solution viscosity in the reverse roll coater or natural roll coater, and by the roll rotation speed and roll surface roughness in the gravure roll coater. ing.

[0004]

However, in a solution having a low viscosity such as a polysilazane solution, it is difficult to adjust the coating amount by adjusting the gap between the doctor roll and the solution. Therefore, it is not possible to coat with a reverse roll coater or a natural roll coater. It is very difficult to control the thickness of the polysilazane coating. Also in the case of a gravure coater, it is difficult to properly control the amount of liquid transfer of the polysilazane solution having a low viscosity to the gravure roll, and it is necessary to provide a gravure roll receiving pan in the solution reservoir. When such a pan is provided, there is a drawback that the saucer pan becomes larger as the coating amount increases and the proportion of the residual liquid increases. Therefore, a coating method of a polysilazane solution is desired which can adjust the coating amount, that is, control the coating thickness, and which can minimize the ratio of the residual liquid.

[0005]

According to the present invention, the above-mentioned problems can be solved by (1) contacting an impregnating member impregnated with a polysilazane solution with an object to be coated, and the impregnating member and the object to be coated. It is solved by a coating method of a polysilazane solution, which is characterized in that an object is relatively moved.

The preferred embodiments of the present invention are listed below. (2) The method according to item (1), wherein the impregnating member is a rotating roller coated with a felt material. (3) The method according to item (1), wherein the impregnating member is a rotating roller coated with a felt material, and the relative movement is to move an object to be coated in its longitudinal direction. (4) Item (1), wherein the article to be coated is a film
The method according to any one of (3). (5) The polysilazane is represented by the following general formula (I):

[0007]

Embedded image

(In the above formula, R ¹ , R ² and R ³ are each independently a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group other than these groups which is directly bonded to silicon. Represents an alkylsilyl group, an alkylamino group, and an alkoxy group.
At least one of R ¹ , R ² and R ³ is a hydrogen atom), which is a polysilazane having a main skeleton composed of units represented by the following formula and having a number average molecular weight of 100 to 50,000:
The method according to any one of (4).

According to the coating method of the present invention, since the coating amount can be adjusted by exuding the polysilazane solution from the surface of the impregnating member, the residual liquid amount can be minimized and A polysilazane coating film having a controlled thickness can be continuously obtained.

The method of the present invention is useful when applying a polysilazane solution having a low viscosity. The term "low viscosity" or "low viscosity" as used herein means that the viscosity of the polysilazane solution at the coating temperature is in the range of 1 to 100 centipoise.

The polysilazane used in the polysilazane solution to which the method of the present invention is preferably applied may be any polysilazane having at least Si-H bond or N-H bond in the molecule, not to mention polysilazane alone. Also, a copolymer of polysilazane and another polymer or a mixture of polysilazane and another compound can be used. Suitable polysilazanes 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. Representative examples of the polysilazane that is preferably used include, but are not limited to, the following.

[0012]

Embedded image

(In the above formula, R ¹ , R ² and R ³ are each independently a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group other than these groups, which is directly bonded to silicon. Represents an alkylsilyl group, an alkylamino group, and an alkoxy group.
At least one of R ¹ , R ² and R ³ is a hydrogen atom), and has a main skeleton composed of a unit represented by the formula: polysilazane having a number average molecular weight of 100 to 50,000.

From the viewpoint of increasing the hardness (denseness) of the obtained coating film, perhydropolysilazane in which R ¹ , R ² and R ³ are all hydrogen atoms in the above general formula (I) is preferable.
Organopolysilazane in which at least one of R ¹ , R ² and R ³ is an organic group (provided that at least one must be a hydrogen atom) is preferable from the viewpoint of increasing the flexibility of the obtained coating film. These polysilazanes and their production methods are described, for example, in Japanese Examined Patent Publication No. 63-16325, D. S.
eyferth et al. Communication of Am. Cer. Soc., C-13, Jan
uary 1983., D. Seyferth et al. Polym. Prepr., Am. Che
See m. Soc., Div. Polym. Chem., 25 , 10 (1984), JP 61-89230 A, JP 62-156135 A, and the like.

The polysilazane which can be preferably used according to the present invention is not practical because the yield at the time of ceramization becomes low when the molecular weight is too low. On the other hand, if the molecular weight is too high, the stability of the solution is low and a sound polysilazane film cannot be obtained. For these reasons, the molecular weight of the polysilazane used is a number average molecular weight with a lower limit of 100, preferably 500. The upper limit is 50,000, preferably 10,000.

As a solvent for preparing the above polysilazane solution, aliphatic hydrocarbons, alicyclic hydrocarbons, hydrocarbon solvents of aromatic hydrocarbons, halogenated methane, halogenated ethane, halogenated benzene, etc. Ethers such as halogenated hydrocarbons, aliphatic ethers and alicyclic ethers, specifically, methylene chloride, chloroform,
Halogenated hydrocarbons such as carbon tetrachloride, bromoform, ethylene chloride, ethylidene chloride, trichloroethane, tetrachloroethane, etc., ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-
Ethers such as dioxyethane, dioxane, dimethyldioxane, tetrahydrofuran, tetrahydropyran, pentanehexane, isohexane, methylpentane, heptane, isoheptane, octane, isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene,
Examples thereof include hydrocarbons such as xylene and ethylbenzene.

According to the present invention, the solid concentration of the polysilazane solution as described above has a viscosity of 1 at the temperature during coating.
Any concentration can be used provided it is in the range of -100 centipoise, preferably 1-60 centipoise. For example, in the case of a polysilazane xylene solution,
A solution containing 5 to 65% by weight, preferably 5 to 58% by weight of polysilazane can be suitably used.

According to the present invention, the impregnable member is impregnated with the polysilazane solution as described above. This impregnable member is
Any material may be used as long as it can absorb and retain a desired amount of the polysilazane solution, but it is preferable that it does not damage the coating film when applied. Examples of the material for such an impregnable member include a felt material and a sponge material. Among them, the reason why the felt material is preferable is that it has excellent liquid retention, does not easily foam, and does not drop fibers. And so on. The impregnating member may have various shapes such as a roller shape and a sponge shape. A particularly preferred impregnating member is a rotating roller coated with felt material.

During coating, the impregnable member is brought into contact with the surface to be coated. The polysilazane solution exudes from the impregnating member at the time of contact, and the polysilazane solution exudes at the time of relative movement with the article to be adhered to the article to be coated uniformly without scratching or impregnation. It is preferable to bring the member into contact with the surface to be coated. Since the coating amount can be controlled by the amount of this exudation, in other words, the coating film thickness can be controlled by this pressure. In order to obtain a uniform polysilazane coating film, this pressure is preferably constant.

The impregnation of the polysilazane solution into the impregnating member can be carried out continuously by a supply means according to the coating amount. For example, when a felt-coated rotating roller is used as the impregnating member, the polysilazane solution may be continuously dripped from the upper part of the rotating roller, or a liquid reservoir may be provided inside the rotating roller to externally From above, the polysilazane solution may be supplied through a solution supply means. In the latter case, for example, the rotating roller may be provided with a communication hole so that the felt material on the surface is impregnated with the polysilazane solution from the liquid reservoir provided inside.

The polysilazane solution is applied by moving the impregnating member and the article to be coated while bringing the impregnating member supplied with the polysilazane solution into contact with the article to be coated. This relative movement can be performed by moving the impregnating member, moving the article to be coated, or both. Preferably, a rotating roller-like impregnating member is used, and coating is performed by moving the object to be coated in its longitudinal direction. The relative moving speed is not particularly limited, but the thickness of the coating film can be adjusted by the moving speed as well as the amount of the polysilazane solution oozing out. When using a rotating roller coated with a felt material, this relative moving speed is preferably 0.5 to 60 m /
Min, more preferably 0.5 to 45 m / min.

The material having the surface to be coated is not particularly limited,
For example, glass and various plastic materials are included. Examples of the plastic material include polycarbonate, polymethyl methacrylate, polyether sulfide, polyester, polypropylene, polyethylene terephthalate, and the like. The area and thickness of the surface to be coated are not particularly limited, and those having any area and thickness according to the application can be adopted. A particularly preferred article to be coated is a plastic film.

When a polysilazane solution is used, the thickness of the dry coating film obtained by one movement of the impregnating member is preferably 0.1 to 2.0 μm, more preferably 0.1 to 2.0 μm.
It is in the range of 1.2 μm. This film thickness can also be controlled by changing the polysilazane concentration in the solution. For example, the film thickness can be increased by increasing the solid content concentration (decreasing the solvent concentration).

The polysilazane coating film having a desired thickness thus obtained is subjected to a drying step if necessary,
By performing a firing step, or a step of performing a humidification treatment after the heat treatment and / or a step of immersing in a water solution containing an acid catalyst or a base catalyst, it is possible to convert the ceramic to substantially SiO ₂ . For the ceramicization of such polysilazane, refer to Japanese Patent Application No. 5-318188 cited above. further,
As another method of ceramization treatment, as described in Japanese Patent Application No. 6-236881, which is also cited above, a polysilazane coating film is brought into contact with an aqueous solution of a silicate ester to form a ceramic composed of SiO _{2 at} room temperature. It can also be converted to. After being made into ceramic in this way, the coating may be subjected to a washing step and / or a drying step, if desired.

The method of the present invention will now be further described with reference to the figures. FIG. 1 illustrates a method of applying polysilazane using an impregnating member 10 composed of a rotating roller 12 coated with a felt material 11. First, the felt material 11 is impregnated with a fixed amount of polysilazane solution. The impregnating member 10 is brought into contact with the article to be coated 15 at a predetermined pressure. While the impregnating member 10 is rotated, the polysilazane solution 13 is dropped and supplied from above the impregnating member 10 from the polysilazane solution supply means 14 at a rate according to the rotation speed (that is, the coating speed). A polysilazane solution that uniformly exudes from the felt material 11 according to the pressure adheres to the article to be coated 15 and has a uniform polysilazane coating film 16 having a desired thickness.
Is continuously obtained.

FIG. 2 similarly illustrates a method of applying polysilazane using an impregnating member 20 composed of a rotating roller 22 coated with a felt material 21. However, a liquid reservoir 27 is provided inside the rotating roller 22,
A polysilazane solution is externally supplied to the solution through the solution supply means 24. Further, the rotation roller 22 has a communication hole 2
8 is provided, and the felt material 2 on the surface from the liquid reservoir 27 is provided.
1 is impregnated with the polysilazane solution. First, the felt material 21 is impregnated with a fixed amount of polysilazane solution. The impregnating member 20 is brought into contact with the article to be coated 25 with a predetermined pressure. The polysilazane solution 23 is rotated at a rate corresponding to the rotation speed (that is, the coating speed) while rotating the impregnating member 20.
Via the solution supply means 24 to the liquid reservoir 27 of the impregnating member 20.
Supply to The polysilazane solution impregnated in the felt material 21 from the liquid reservoir 27 through the communication holes 28 uniformly exudes from the felt material 21 in accordance with the pressure and adheres to the article to be coated 25, and a uniform polysilazane having a desired thickness is obtained. The coating film 26 is continuously obtained.

[0027]

Example: Tonen perhydropolysilazane Type-1
A 20% xylene solution of (PHPS-1; number average molecular weight 900) was prepared and used as a coating composition. While the polyester (PET) film base material having a thickness of 100 μm, a width of 60 cm and a total length of 300 mm was conveyed at 10 m / min, the coating composition was dried to give a dry coating film of 0.1.
It was applied to one side by a gravure coating method so as to have a thickness of 6 μm. At this time, a roller (roller diameter 50 mmφ, length 800 mm) coated with a polyolefin resin felt material with a coating thickness of 3 mm as shown in FIG. 1 was brought into contact with the film while rotating it in accordance with the transport of the film ( (Contact angle = 100 degrees, film tension = 3.6 kg for conveyance).

After coating, the polysilazane coating film was dried by passing it through a solvent drying zone having a temperature of 150 ° C. and a length of 15 m at the above-mentioned conveying speed. The solvent-removed polysilazane-coated film was conveyed to a heating / humidifying region having an internal conveying distance of 100 m, which was maintained at a temperature of 110 ° C. and a relative humidity of 96% RH, and the polysilazane coating film was subjected to ceramization treatment for 10 minutes. The ceramic film thus continuously obtained had good uniformity.

[0029]

According to the coating method of the present invention, since the coating amount can be adjusted by exuding the polysilazane solution from the surface of the impregnating member, the residual liquid amount can be minimized. At the same time, a polysilazane coating film having a controlled thickness can be continuously obtained.

[Brief description of drawings]

FIG. 1 is a schematic view illustrating one embodiment of the method of the present invention.

FIG. 2 is a schematic view illustrating another embodiment of the method of the present invention.

[Explanation of symbols]

 10, 20 ... Impregnating member 11, 21 ... Felt material 12, 22 ... Rotating roller 13, 23 ... Polysilazane solution 14, 24 ... Solution supply means 15, 25 ... Workpiece 16, 26 ... Polysilazane coating film 27 ... Liquid Reservoir 28 ... Communication hole

Claims (1)

[Claims] 1. A method for applying a polysilazane solution, which comprises bringing an impregnating member impregnated with a polysilazane solution into contact with an object to be coated and moving the impregnating member and the object to be relative to each other. .