JP4668937B2 - Method for forming water-repellent film and article coated with water-repellent film - Google Patents

Description

  The present invention relates to a method for forming a water-repellent film and a water-repellent film-coated article. More specifically, the present invention relates to a method for forming a water-repellent coating by applying a coating solution for forming a water-repellent coating on the surface of glass or the like and a water-repellent coating-coated article obtained by this method.

In the production of a functional glass having a water-repellent coating formed on a substrate such as glass, in order to form a water-repellent coating on the substrate, a water-repellent material is applied on the substrate. If only these are applied, the excess of the water-repellent material present on the surface of the base material may cause appearance defects such as uneven reflection color and haze, and may deteriorate the water-repellent performance.
Therefore, conventionally, as a method of forming a water-repellent coating on a substrate such as glass, the coating liquid for forming the water-repellent coating is adhered to paper, cloth, etc., and coated on the substrate until it becomes transparent. Excessive water-repellent coating-forming coating solution was removed while changing paper and cloth many times. However, since this method has low productivity, various studies have been made so far.

For example, a method of forming a water-repellent coating has been proposed in which a coating liquid for forming a water-repellent coating is excessively applied to the glass surface, and then the excess is removed (see Patent Document 1). According to this method, productivity is improved as compared with conventional methods, and the occurrence of reflected color unevenness and haze can be suppressed by wiping off the surplus.
Further, the top surface of the float glass is selected, and a solution containing a silane compound is brought into contact therewith to form a monomolecular film (water-repellent coating) having CF ₃ groups or CH ₃ groups exposed on the surface, and after drying, A method for forming a water-repellent coating has been proposed in which a film having a siloxane bond that is not chemically bonded to a silicate on the top surface is dissolved in a solvent by washing with a solvent (see Patent Document 2). According to this method, productivity is improved as compared with the conventional methods, and a functional float glass having a constant performance can be obtained by a simple method.
Furthermore, using a coating solution for forming a specific water-repellent coating, using the surface tension of the coating solution, a coating film with a uniform wet thickness is formed on the substrate and dried, so that the subsequent wiping There has been proposed a method for forming a water-repellent coating that does not require a raising step (step of removing excess by wiping with a cloth soaked with a solvent) (see Patent Document 3). According to this method, a water-repellent film can be formed on a substrate with excellent productivity.

JP-A-11-79789 JP 2001-31447 A Japanese Patent Laid-Open No. 2000-21875

However, the method disclosed in Patent Document 1 requires a wiping step, and the method disclosed in Patent Document 2 requires a washing step with a solvent, which is not efficient in terms of productivity. It is enough. On the other hand, although the method disclosed in Patent Document 3 is excellent in productivity, in order to obtain a uniform wet thickness, it is limited to a range where the shape and state of the substrate are present. That is, when applying to a surface having a large curved shape, a place where the water repellent liquid accumulates may occur, which may cause poor appearance.
Therefore, there has been a demand for a method of forming a water-repellent coating that is highly productive and does not require a wiping process without being restricted by the shape and state of the substrate.
An object of the present invention is to provide a method for forming a water-repellent coating on a substrate with high productivity without being restricted by the shape and state of the substrate.

As a result of intensive studies to achieve the above object, the present inventor has scattered the aggregates of substantially circular water-repellent materials on the water-repellent coating after drying, and the average diameter of the aggregates is 20 to 20%. By controlling to 50 μm, it has been found that even if the wiping process is not performed, appearance defects such as uneven reflection color and haze are not caused, and good water repellency can be obtained. The present invention has been completed based on such findings.
That is, the present invention
[1] A method of forming a water-repellent coating on a substrate using a water-repellent coating-forming coating solution containing a water-repellent material, wherein the water-repellent coating-forming coating solution is spray-coated on the substrate. And having a coating step and a drying step applied to the substrate, and after drying, a substantially circular aggregate of water-repellent material is scattered on the water-repellent coating, and the average diameter of the aggregate is controlled to 20 to 50 μm. A method for forming a water-repellent coating,
[2] The method for forming a water-repellent film according to [1] above, wherein a two-fluid spray nozzle is used in the spray coating method,
[3] The method for forming a water-repellent coating according to the above [2], wherein the two-fluid spray is set so that an average particle diameter of the water is 5 to 30 μm when water is sprayed from a nozzle. ,
[4] The solvent of the coating liquid for forming the water-repellent film contains at least one non-aqueous solvent selected from the group consisting of hydrocarbon solvents, silicone solvents, and fluorine solvents, and the non-aqueous solvent at 25 ° C. The method for forming a water-repellent coating film according to any one of the above [1] to [3], wherein the vapor pressure at is at least 500 Pa,
[5] The above [1] to [1], wherein the solvent of the water-repellent coating forming coating solution contains a non-aqueous solvent, and the non-aqueous solvent contains at least paraffinic hydrocarbons distilled at 210 ° C. or lower by atmospheric distillation. 4], the method for forming a water-repellent coating according to any one of
[6] The method for forming a water-repellent coating according to the above [4] or [5], wherein the coating liquid for forming the water-repellent coating is obtained by dissolving a fluoroalkyl group-containing silane compound in the solvent. [8] A water-repellent coating-coated article provided with a water-repellent coating on a substrate, the water-repellent coating being dotted with aggregates of substantially circular water-repellent materials, and the average diameter of the aggregates being 20 to 20 A water-repellent film-coated article characterized by being 50 μm,
Is to provide.

  According to the present invention, a water-repellent coating can be formed on a substrate with high productivity without being restricted by the shape and state of the substrate. In addition, the water-repellent film-coated article obtained by the method of the present invention has excellent water repellency and durability, and is excellent in appearance quality.

In the method for forming a water-repellent film of the present invention, a water-repellent film-forming coating liquid containing a water-repellent material (hereinafter sometimes simply referred to as “water-repellent liquid”) is applied on a substrate by a spray coating method. It has a coating process and a drying process. Then, after drying, a substantially circular aggregate of water-repellent material is scattered on the water-repellent coating, and the average diameter of the aggregate is controlled to 20 to 50 μm.
The aggregate is a process in which the water-repellent material is aggregated in a process (drying process) in which the solvent in the water-repellent liquid is volatilized, and has an approximately circular shape that is scattered on the formed water-repellent film. It is an excess water repellent material. However, by setting the average diameter of the aggregate to 50 μm or less, even when the surplus of such a water-repellent material is present on the substrate, the reflection color unevenness or Appearance defects such as haze do not occur. On the other hand, if there is a necessary amount of water-repellent material bonded to the surface of the substrate, the presence of the surplus is not necessarily required, and sufficient water-repellent performance is exhibited. When the average diameter is less than 20 μm, the required amount of water repellent material is not supplied and sufficient water repellency performance may not be exhibited. From the above viewpoint, the average diameter of the aggregate is preferably in the range of 20 to 40 μm.

As a method of dispersing the aggregates on the water-repellent coating and controlling the average diameter of the aggregates to 20 to 50 μm, a method of applying a water-repellent liquid on the substrate by a spray coating method is preferable. In the spray coating method, the average particle diameter of the water repellent liquid to be sprayed can be easily controlled, and by this control, the average diameter of the aggregate after drying can be controlled to 20 to 50 μm. In particular, it is preferable to use a two-fluid spray nozzle.
A two-fluid spray nozzle pulverizes and atomizes a liquid with a high-speed airflow such as compressed air, and can spray fine particles at a low pressure. In addition, it is preferable because the droplet diameter sprayed from the nozzle can be easily adjusted by changing the air-water ratio determined from the ratio of gas to liquid.

As a method for controlling the average diameter of the aggregate to 20 to 50 μm, for example, when water is sprayed from a two-fluid spray nozzle, the condition is set so that the average particle diameter of the water is 5 to 30 μm. Can be performed. As will be described later, various water repellent materials and solvents can be selected as the water repellent liquid itself. The average diameter of the aggregate and the two-fluid spray nozzle are selected depending on the ease of aggregation of the water repellent material and the drying speed of the solvent. The average particle size of the droplets sprayed from is not always the same. However, by setting the conditions as described above, the average diameter of the aggregates of the water-repellent material scattered on the water-repellent coating can be controlled to 20 to 50 μm. In addition, since the average diameter of the aggregate tends to increase as the average particle diameter of the droplets sprayed from the two-fluid spray nozzle increases, even if the type of the water-repellent material or the solvent is changed, the two-fluid By appropriately changing the average particle diameter of water sprayed from the spray nozzle within the above range, an aggregate of water repellent having an optimum average diameter can be obtained.
In order to control the average particle diameter of water sprayed from the two-fluid spray nozzle within the above range, the ratio of gas to liquid, that is, air pressure and liquid pressure (water pressure) are controlled. Specifically, the average particle diameter of the sprayed water repellent liquid increases as the water pressure increases, and the average particle diameter decreases as the air pressure increases.

  When applying the water repellent liquid on the substrate by the spray coating method, the spray nozzle may be moved while fixing the substrate, or the substrate may be moved while fixing the spray nozzle. For example, the water repellent liquid The water-repellent film can be formed on the entire surface (front surface and back surface) of the substrate by passing the substrate through the spray atmosphere. Moreover, when it is desired to provide a part where the water-repellent film is not formed on a part of the substrate surface, it can be easily obtained by masking the part.

  The water repellent liquid is preferably obtained by dissolving a fluoroalkyl group-containing silane compound as a water repellent in a non-aqueous solvent. As the fluoroalkyl group-containing silane compound, a silane compound containing a fluoroalkyl group and containing an alkoxyl group, an acyloxy group, or a chlorine group can be preferably used. For example, a compound represented by the following chemical formula (1) Can be mentioned. Of these, a single substance or a combination of a plurality of substances can be used.

_{CF 3 - (CF 2) n} -R-SiX p Y 3-p ·· (1)
Here, n is an integer of 0 to 12, preferably an integer of 3 to 12, and R is a divalent organic group having 2 to 10 carbon atoms (for example, a methylene group or an ethylene group) or a group containing a silicon atom and an oxygen atom. , X is hydrogen or a monovalent hydrocarbon group having 1 to 4 carbon atoms (for example, alkyl group, cycloalkyl group, allyl group) or a derivative thereof, p is 0, 1 or 2, Y is carbon An alkoxyl group having 1 to 4 atoms, an acyloxy group, or a halogen atom.

Specific examples of the compound represented by the chemical formula (1) include the following.
_{C 6 F 13 CH 2 CH 2} Si (OCH 3) 3, C 7 F 15 CH 2 CH 2 Si (OCH 3) 3, C 8 F 17 CH 2 CH 2 Si (OCH 3) 3, C 9 F 19 CH ₂ CH ₂ Si (OCH ₃ ) ₃ , C ₁₀ F ₂₁ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , C ₆ F ₁₃ CH ₂ CH ₂ SiCl ₃ , C ₇ F ₁₅ CH ₂ CH ₂ SiCl ₃ , C ₈ F ₁₇ CH ₂ CH ₂ SiCl ₃ , C ₈ F ₁₇ CH ₂ CH ₂ Si (CH ₃ ) Cl ₂ , C ₉ F ₁₉ CH ₂ CH ₂ SiCl ₃ , C ₁₀ F ₂₁ CH ₂ CH ₂ SiCl ₃ ,

_{C 8 F 17 CH 2 CH 2} Si (OC 2 H 5) 3, C 8 F 17 CH 2 CH 2 Si (OCOCH 3) 3

Among these, C ₈ F ₁₇ CH ₂ SiCl ₃ (heptadecafluorodecyltrichlorosilane) is preferable because of its high reactivity with the surface of the substrate.

In addition, examples of the non-aqueous solvent include hydrocarbon solvents, silicone solvents, fluorine solvents, and the like, and it is preferable to contain at least one of these from the viewpoint of easily obtaining the effects of the present invention. Examples of the hydrocarbon solvent include normal paraffins such as n-butane, n-heptane, n-octane, and n-nonane; isoparaffins such as isobutane and isopentane. Silicone solvents include hexamethyldisiloxane, octane. Examples thereof include methyltrisiloxane, and examples of the fluorine-based solvent include those containing a perfluorocarbon having 8 and / or 9 carbon atoms as a main component.
In particular, among these solvents, those having high volatility are preferable, and specifically, those having a vapor pressure at 25 ° C. of 500 Pa or more, and more preferably 1000 Pa or more are preferable.

  Further, the non-aqueous solvent may be a paraffinic hydrocarbon distilled at 210 ° C. or less by atmospheric distillation. When a paraffinic hydrocarbon is used as the non-aqueous solvent, it is particularly 150 by atmospheric distillation. It is preferable to use paraffinic hydrocarbons distilled at a temperature of less than or equal to ° C. Commercially available products include IP-solvent 1620 (distillation range 166 to 202 ° C.), IP-solvent 1016 (distillation range 73 to 140 ° C.) (above, manufactured by Idemitsu Kosan Co., Ltd.), Nisseki Isosol 200 (distillation range 73 to 140). C, Shin Nippon Oil Co., Ltd.), KF-96L-0.65CS (vapor pressure 4700 Pa (25 ° C)), KF-96L-1CS (vapor pressure 530 Pa (25 ° C)) (Shin-Etsu Chemical Co., Ltd. ), Fluorinert FC-3283 (vapor pressure 2000 Pa (23 ° C.)), Fluorinert FC-77 (vapor pressure 5599 Pa (20 ° C.)) (the above, Sumitomo 3M Co., Ltd.) and the like.

When such a highly volatile non-aqueous solvent is used, when the water-repellent liquid is applied by the spray coating method, the solvent in the coating liquid ejected from the nozzle partially volatilizes before adhering to the substrate, and the water-repellent liquid is repelled. As the water material condenses on the substrate, the average diameter of the aggregate can be easily controlled to 20 to 50 μm. Further, in the present invention, since the wiping process is not required after the water repellent liquid is applied, the substrate can be transferred to another process immediately after the application. The high volatility has the advantage that handling becomes easy and workability is improved.
In addition, the said hydrocarbon solvent, a silicone type solvent, and a fluorine-type solvent can be used individually by 1 type or in mixture of 2 or more types.

By using the method of the present invention, a water repellent coating is provided on a substrate, and a substantially circular aggregate of water repellent material is scattered on the water repellent coating, and the average diameter of the aggregate is 20 to 50 μm. A water repellent coated article is obtained. This water-repellent film-coated article has excellent water repellency and durability, and is excellent in appearance quality.
Here, although it does not specifically limit as a base material, A transparent glass plate, a resin plate, a resin film, etc. can be used suitably. The thickness of the substrate is appropriately selected according to the application and is not particularly limited, but is usually about 0.01 to 10 mm.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example. The evaluation method is described below.
Evaluation Method (1) Average Diameter of Aggregates of Water-Repellent Material For the water-repellent glass obtained in each Example and Comparative Example, the size of the aggregate of water-repellent materials scattered on the surface of the substrate was measured with a laser microscope. ("VK-8500" manufactured by Keyence Corporation) was used to measure 6 points, and the average value was taken as the average diameter of the aggregate of water repellent material.
(2) Water-repellent performance (2-1) Contact angle About the water-repellent glass obtained in each Example and Comparative Example, using a contact angle meter ("CA-DT" manufactured by Kyowa Interface Science), the mass of 2 mg The static contact angle due to water droplets was measured.
(2-2) Falling angle The glass angle (falling angle) when 50 μL of water drops are placed on the surface of the water-repellent glass placed horizontally, the glass is gradually tilted, and the water drops placed on the surface start to roll. Was measured.
(3) Haze value About the water-repellent glass obtained by each Example and the comparative example, the haze value of the surface was measured using the haze meter ("HZ-1" by Suga Test Instruments).

Example 1
0.2 g of heptadecafluorodecyltrichlorosilane (ASIMAX Co., Ltd. “SIH5841.0”) was added to 99.8 g of isoparaffin (Idemitsu Kosan Co., Ltd. “IP-Solvent 1620”) and stirred for 30 minutes to repel the water. An aqueous solution was obtained. The concentration of heptadecafluorodecyltrichlorosilane (FAS concentration) is 0.2% by mass.
This water-repellent solution is applied on the surface of a glass substrate (600 × 600 mm) washed with a spray coating method in an environment at a temperature of 20 ° C. and a relative humidity of 20%, and is dried in the same environment for about 10 minutes. An aqueous glass was obtained. The conditions for spray coating are as follows.
<Conditions for spray coating>
Spray nozzle; SUE18A (manufactured by Spraying System Japan Co., Ltd.)
Fluid pressure: 0.05 MPa
Air pressure: 0.1 MPa
Average particle diameter of water when water is sprayed from the nozzle under the same conditions (Sauta average particle diameter); about 18 μm
Nozzle-glass distance; 480 mm
Nozzle moving speed: 11.4 m / min (moving the nozzle with the glass substrate fixed)
The obtained water-repellent glass was evaluated by the above method. The results are shown in Table 1.

Example 2
A water-repellent glass was obtained in the same manner as in Example 1 except that 99.7 g of isoparaffin and 0.3 g of heptadecafluorodecyltrichlorosilane (FAS concentration; 0.3 mass%) were used. The results evaluated in the same manner as in Example 1 are shown in Table 1.

Example 3
A water-repellent glass was obtained in the same manner as in Example 1 except that the air pressure was 0.15 MPa under the spray coating conditions. The results evaluated in the same manner as in Example 1 are shown in Table 1. In addition, this spray coating conditions are conditions which show about 15 micrometers in the average particle diameter (Sauta average particle diameter) of the water at the time of spraying water from a nozzle.

Example 4
A water-repellent glass was obtained in the same manner as in Example 2 except that the air pressure was 0.15 MPa under the spray coating conditions. The results evaluated in the same manner as in Example 1 are shown in Table 1. The spray coating conditions are the same as in Example 3.

Comparative Example 1
A water-repellent glass was obtained in the same manner as in Example 2 except that the air pressure was 0.05 MPa under the spray coating conditions. The results evaluated in the same manner as in Example 1 are shown in Table 1. In addition, this spray coating conditions are conditions which show about 32 micrometers in the average particle diameter (Sauta average particle diameter) of the water at the time of spraying water from a nozzle.

Comparative Example 2
A water-repellent glass was obtained in the same manner as in Example 1 except that the air pressure was 0.05 MPa under the spray coating conditions. The results evaluated in the same manner as in Example 1 are shown in Table 1. In addition, this spray coating conditions are conditions which show about 32 micrometers in the average particle diameter (Sauta average particle diameter) of the water at the time of spraying water from a nozzle similarly to the comparative example 1. FIG.

The water-repellent glass produced according to Examples 1 and 3 has good water-repellent performance and appearance quality without performing post-processes such as wiping and washing with a solvent, and is highly productive and water-repellent. It was confirmed that glass could be manufactured. Further, from the results of Examples 2 and 4, it was confirmed that even when the concentration of the water repellent material in the water repellent liquid was increased 1.5 times, the water repellent performance and appearance quality were good.
On the other hand, since the water repellent glass of Comparative Example 1 has a large average diameter of the water repellent material aggregate of 276 μm after drying, it exhibits a sufficient water repellent performance but has a high haze value and poor appearance quality. It was. Further, the water repellent glass of Comparative Example 2 has a small average diameter of the aggregate of water repellent material after drying compared with Comparative Example 1, but is still as large as 82.5 μm. In comparison, the haze value is high.

  Further, from the results of Examples and Comparative Examples, the relationship between the average diameter (μm) and the haze (%) of the aggregate of the water repellent material is summarized as shown in FIG. As apparent from the results of Table 1 and FIG. 1, the haze value can be reduced to 0.5% or less by setting the average diameter of the aggregate of the water-repellent material after drying to 50 μm or less.

  According to the present invention, a water-repellent coating can be formed on a substrate with high productivity without being restricted by the shape and state of the substrate. In addition, the water-repellent film-coated article obtained by the method of the present invention has excellent water repellency and durability, and is excellent in appearance quality.

It is a figure which shows the correlation of the average diameter (micrometer) and haze (%) of the aggregate of a water repellent material.

Claims (7)

  A method of forming a water-repellent coating on a substrate using a water-repellent coating-forming coating solution containing a water-repellent material, wherein the water-repellent coating-forming coating solution is applied on the substrate by a spray coating method. A coating process and a drying process, and after drying, a substantially circular aggregate of water-repellent material is scattered on the water-repellent coating, and the average diameter of the aggregate is controlled to 20 to 50 μm. A method for forming an aqueous film.   The method for forming a water-repellent coating according to claim 1, wherein a two-fluid spray nozzle is used in the spray coating method.   The method of forming a water-repellent coating according to claim 2, wherein the two-fluid spray is set so that when water is sprayed from a nozzle, the average particle diameter of the water is 5 to 30 µm.   The solvent of the coating liquid for forming the water repellent film contains at least one non-aqueous solvent selected from the group consisting of hydrocarbon solvents, silicone solvents and fluorine solvents, and the vapor pressure of the non-aqueous solvent at 25 ° C. The method for forming a water-repellent coating according to claim 1, wherein the water repellent film is 500 Pa or more.   The solvent of the coating liquid for forming the water-repellent film contains a non-aqueous solvent, and the non-aqueous solvent contains at least paraffinic hydrocarbons distilled at 210 ° C. or lower by atmospheric distillation. A method for forming the water-repellent coating as described.   The method for forming a water-repellent coating according to claim 4 or 5, wherein the coating liquid for forming the water-repellent coating is obtained by dissolving a fluoroalkyl group-containing silane compound in the solvent.   A water-repellent coating-coated article provided with a water-repellent coating on a substrate, the water-repellent coating being dotted with aggregates of substantially circular water-repellent materials, and the average diameter of the aggregates being 20 to 50 μm A water-repellent film-coated article characterized by the above.

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