JP2001259513A - Method for forming water repellent film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a water repellent film having practical surface hardness. SOLUTION: On the surface of a resin layer, a coating containing a solvent which can swell or dissolve the resin of the resin layer, polyvinylidene fluoride resin powder, and flouroplastic powder of a high melting point is applied and heat-treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a water-repellent film having excellent water repellency and practical surface hardness.

[0002]

2. Description of the Related Art Prevention of surface contamination of structures due to rainwater caused by air pollution, prevention of snow and ice adhesion to power transmission / communication facilities and buildings in heavy snow areas, prevention of icing on hulls traveling in cold seas, marine For the purpose of preventing organisms from adhering to structures, waterproofing (water-repellent) treatment of various tents, and various other purposes, it is required to make the material surface water-repellent. Conventionally, several techniques have been proposed to satisfy this demand. For example, an uncured liquid resin having a water absorption of 0.5% or less is applied to the surface of the base material, and the surface of the uncured resin is collided so as to partially embed hydrophobic fine particle powders, and then the resin is cured. A technique of adhering and fixing hydrophobic fine particle powder in a resin has been proposed (JP-A-6-296924). In this proposal, an electrostatic coating technique is used as a means for colliding the hydrophobic fine particles so as to partially bury them. The above-mentioned proposal is extremely rich in water repellency, with the contact angle of water on the surface of the obtained film being 160 to 170 °, and is excellent from the viewpoint of water repellency. However, since large-scale facilities are required, such as the necessity of an electrostatic coating apparatus for forming a film having high water repellency, there is a problem that the cost is high and it is not easy to implement. Therefore, the present inventors aimed at providing a technique capable of easily forming a film having high water repellency with the aim of providing a paint containing a solvent for swelling or dissolving the resin on the surface of the resin layer and a fluorine-based resin powder on the surface of the resin layer. A method for forming a water-repellent film by applying a coating was proposed (Japanese Patent Laid-Open No. 9-5304).
1).

[0003]

However, this film had a drawback that the surface hardness was 6B in pencil hardness and it was soft and easily damaged. The present invention has been made in view of the drawbacks of the above technology, and has as its object to provide a technology that can improve the surface hardness and easily form a film having high water repellency.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the present invention applies a solvent containing a solvent capable of swelling or dissolving the resin of the resin layer, a polyvinylidene fluoride resin powder, and a higher melting point fluorine-based resin powder to the surface of the resin layer, and performing a heat treatment. A method for forming a characteristic water-repellent film is provided. The present invention also provides a method for forming a water-repellent film, wherein the resin layer is formed by applying a paint containing a room-temperature-curable resin. Further, the present invention provides the method for forming a water-repellent film, wherein the surface roughness of the water-repellent film is 1 to 5 μm in center line average roughness Ra.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a resin layer to which a paint is applied only needs to be present on at least the surface of a substrate to be coated, and even if the entire substrate is composed of a resin layer. It may be provided only on the surface of the substrate. The material of the substrate is not particularly limited, and various inorganic materials and organic materials can be used. In order to provide the resin layer only on the surface of the base material, for example, it can be performed by applying a coating material containing a cold-setting resin to the base material. This is because if the surface to be modified to water repellency is not composed of resin, or even if composed of resin, the resin cannot be swollen or dissolved with any solvent (solvent) This is done in some cases. The resin layer may be any as long as the resin swells or dissolves with the solvent and can partially fill the polyvinylidene fluoride resin powder and the higher melting point fluororesin powder, and the thickness is at least 2 μm or more. Is preferably 10 μm or more, and usually about 10 to 1000 μm.

The resin of the resin layer is not particularly limited as long as it is soluble or swellable in a solvent, and examples thereof include a room-temperature-curable resin composed of a resin having a reactive group and a crosslinking agent. As the resin having a reactive group, for example, a fluorine-based resin such as an alternating copolymer of fluoroolefin and vinyl ether (a fluorine-based resin different from that used for the fluorine-based resin powder), an epoxy-based resin, a silicon-based resin Resin, urethane resin and the like. In addition to the cold-setting resin, a vinyl chloride resin, a polyolefin resin such as polyethylene and polypropylene, a polystyrene resin, a polyester resin, a polyamide resin, and the like are also used. That is, any material that can be swelled or dissolved by any solvent may be used.
The paint used in the present invention contains a solvent capable of swelling or dissolving the resin of the resin layer, a powder of poly (vinylidene fluoride) resin, and a powder of a fluorine-based resin having a higher melting point.

As the solvent capable of swelling or dissolving the above resin, for example, aromatic hydrocarbon, ether, lower alkyl alcohol, thinner and the like are used. The aromatic hydrocarbon is preferably an aromatic hydrocarbon having 6 to 9 carbon atoms, and specific examples thereof include benzene, toluene, and xylene. Examples of the ether include ethers having 3 to 10 carbon atoms, and specific examples thereof include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monophenyl ether, and ethylene glycol monobenzyl ether. Cellosolve and the like. Lower alkyl alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol,
Isobutyl alcohol and the like. Of course, it is not limited to these. That is, an appropriate material may be selected according to the resin on the surface. The solvent capable of swelling or dissolving the resin of the resin layer preferably does not dissolve the polyvinylidene fluoride resin powder and the fluorine resin powder having a higher melting point.

Examples of the polyvinylidene fluoride resin constituting the polyvinylidene fluoride resin powder include a homopolymer of vinylidene fluoride and a copolymer of vinylidene fluoride and another fluoroolefin. The other fluoroolefin may be a compound containing a fluorine atom and a halogen atom other than the fluorine atom. Perhaloolefins in which a hydrogen atom directly bonded to a carbon atom forming an ethylenically unsaturated group is completely substituted with a halogen atom are particularly preferred. Specific examples of other fluoroolefins include tetrafluoroethylene, chlorotrifluoroethylene,
Trifluoroethylene, vinyl fluoride, hexafluoropropylene and the like. Other fluoroolefins may be used alone or in combination of two or more.

The proportion of structural units based on another fluoroolefin in a copolymer of vinylidene fluoride and another fluoroolefin is preferably 10% or less. The molecular weight of the polyvinylidene fluoride resin is not particularly limited, but is preferably 100,000 to 1,000,000. The particle size of the polyvinylidene fluoride resin powder is preferably from 0.1 to 50 μm, particularly preferably from 1 to 20 μm. If the particle size is too small, it is difficult to handle and it is difficult to obtain. If the particle size is too large, sufficient dispersibility in a solvent cannot be obtained. The melting point of the fluorine-based resin constituting the higher melting point fluorine-based resin powder may be higher than the melting point of the polyvinylidene fluoride resin constituting the polyvinylidene fluoride resin powder. , 100 ° C or higher is particularly preferred.

[0010] Specific examples of the fluorine-based resin include resins such as polytetrafluoroethylene resin and graphite fluoride. As the polytetrafluoroethylene resin, a homopolymer of tetrafluoroethylene,
Copolymers of tetrafluoroethylene with a monomer copolymerizable with tetrafluoroethylene are exemplified. As copolymerizable monomers,
For example, perfluoroolefins such as hexafluoropropylene, olefins such as ethylene and propylene, and the like can be mentioned. These copolymerizable monomers may be used alone or in combination of two or more.

[0011] Further, those having a surface coated with the fluorine-based resin may be included. Specific examples of commercially available products include Sefral Lube and Asahi Glass manufactured by Central Glass Co., Ltd.
Fluon powder, Fluon lubricant, A
G-Lube and KMP manufactured by Shin-Etsu Chemical Co., Ltd. can be mentioned. The particle size of the fluororesin powder is not particularly limited, but is, for example, in the range of 1 to 60 μm. Preferably, 1
10 μm, more preferably about 2 to 10 μm. The preferred range of the ratio between the polyvinylidene fluoride resin powder and the higher melting point fluororesin powder is 1: 1 to 3 by weight.
1, and the preferred range of the total of both powders and the solvent ratio is 1: 2 to 2: 1 by weight. The coating material can be produced, for example, by dispersing the polyvinylidene fluoride resin powder and a fluorine resin powder having a higher melting point in the solvent while, for example, stirring or applying ultrasonic waves.

In the present invention, this fluororesin powder-dispersed coating material is applied to the surface of a resin layer as a base. Examples of the coating means include brush coating, dip coating, spray coating, and other suitable means. When applied, the solvent swells or dissolves the underlying resin layer, so that the polyvinylidene fluoride resin powder and the fluorine resin powder having a higher melting point can be partially filled in the resin layer. The amount of paint applied is 1 to 200
preferably ^{g / m 2, 10~100g / m} 2 is particularly preferred. The coating temperature is preferably from 0 to 60 ° C, particularly preferably from 10 to 40 ° C. After application, the resin layer preferably has a ripening time for swelling or dissolving it sufficiently with a solvent, and the aging time is not particularly limited, but is preferably 4 hours or more, and particularly preferably 8 hours or more. . There is no upper limit for the aging time, but it may be appropriately selected from the working efficiency, and usually within 12 hours. Aging temperature is 0-6
0 ° C is preferable, and 10 to 40 ° C is particularly preferable.

In the present invention, heat treatment is performed after the application of the paint. The heat treatment temperature is preferably from 100 to 180C, more preferably from 140 to 175C. The heat treatment melts the polyvinylidene fluoride resin powder and fixes the high melting point fluororesin powder. It is preferable that the high melting point fluororesin powder is fixed such that a part of the high melting point fluororesin powder is taken in the resin layer and the rest is exposed from the resin layer. The surface roughness of the water-repellent coating formed by the present invention is preferably 1 to 5 μm in center line average roughness Ra, and more preferably about 2 to 4.5 μm.

After the heat treatment, a compound having water repellency or oil repellency may be further applied as a top coat on the surface of the water repellent coating. Examples of the compound having water repellency or oil repellency include a resin containing a perfluoroalkyl group, a perfluoroalkylalkoxysilane, and an alkylalkoxysilane containing a long-chain alkyl group. The thickness of the top coat is not particularly limited, but is preferably 0.05 to 1 μm.
1 to 0.5 μm is particularly preferred. The surface roughness of the water-repellent coating after the top coat is applied is preferably the above-mentioned center line average roughness. The water repellent coating of the present invention preferably has a high water repellency, for example, a contact angle of water droplets of 150 ° or more.

Articles having the water-repellent coating of the present invention include, for example, automobiles, trains, helicopters, ships, bicycles,
Transportation equipment such as snowmobiles, ropeways, lifts, hovercraft, motorcycles, sashes, shutters, water storage tanks, doors, balconies, building skin panels, roofing materials, stairs, skylights, fences and other building components, buildings Outer walls, guardrails, pedestrian bridges, sound barriers, signs, expressway side walls, railway viaducts, bridges and other road components, tanks, pipes, towers,
Plant facilities such as chimneys, greenhouses, greenhouses, silos, agricultural facilities such as agricultural sheets, telephone poles, power transmission towers,
Examples include communication equipment such as a parabolic antenna, electric wiring box, lighting equipment, electric equipment such as an outdoor air conditioner and a washing machine.

[0016]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited thereto. [Example 1] Polyvinylidene fluoride resin powder (average particle diameter 1 µm, weight ratio 30% with respect to sefral lube (trade name, manufactured by Central Glass Co., Ltd., average particle diameter 4 µm, melting point 315 ° C) of fluororesin powder) Molecular weight 100,00
0, melting point 170 ° C.)
It was dispersed in a volume part of xylene solvent to prepare a paint. In order to form a resin layer on the surface of the base material (aluminum plate), a paint of Lumiflon LF-200C (trade name, fluororesin manufactured by Asahi Glass Co., Ltd.) is applied to form a 25 μm-thick fluororesin coating. did. After the application, the coating was allowed to stand at room temperature for several hours and the surface was dried. Then, the above-mentioned paint containing sefral lube powder, polyvinylidene fluoride resin powder, and xylene was spray-coated. When left at room temperature (23 ° C.) for several hours, a part of the polyvinylidene fluoride resin powder and cefrallube powder is taken into the coating film of Lumiflon LF-200C swollen by xylene and partially embedded and fixed. Was. Then, this coating film was kept in a dryer at 170 ° C. for 1 hour to obtain a water-repellent film.

In the obtained water repellent film, the polyvinylidene fluoride resin powder was partially melted and fixed to the cefral lube powder. The surface roughness of the water-repellent coating is the center line average roughness Ra
And then immersed in a topcoat solution consisting of a 5% by weight solution of metaxylene hexafluoride of a perfluoroalkylethyl acrylate polymer (perfluoroalkyl group having a carbon chain length of 8 and a molecular weight of 20,000). After taking it out, it was naturally dried for one day and the surface of the water-repellent coating was covered with a top coat (0.1 μm in thickness). The contact angle of a water droplet of the water-repellent coating having such surface characteristics is 158.
接触, and the contact angle of liquid paraffin was 120 °.
The surface hardness measured by a pencil hardness tester was B.

[Example 2] In Example 1, a resin layer was formed using Epilite 1000 (epoxy resin manufactured by Tope) instead of Lumiflon LF-200C.
A water-repellent coating was obtained in the same manner except that an epilite-based thinner was used as a solvent for swelling or dissolving the resin of the resin layer. In the obtained water-repellent film, a part of the cefral lube powder was incorporated into the epoxy resin film of the resin layer and partially embedded and fixed, and the center line average roughness Ra was 2 to 3 μm. The contact angle of the water droplet of the water repellent film is 160 °,
The contact angle of the liquid paraffin was 120 °. The surface hardness measured by a pencil hardness tester was B.

Example 3 A water-repellent film was obtained in the same manner as in Example 1, except that the top coat was not performed. The obtained water-repellent film is made of a resin layer, Lumiflon LF-200.
Part of Sefrallube powder is taken into the coating film of C,
Partly buried and fixed, center line average roughness Ra is 2-3
It had a surface characteristic of μm. The resulting water-repellent film is
The contact angle of the water droplet was 165 °. The surface hardness measured by a pencil hardness tester was B.

Example 4 In Example 2, fluorinated graphite particles (average particle diameter 5 μm) were used in place of cefural lube powder.
m) was performed in the same manner except that m) was used. In the obtained water-repellent film, a part of the fluorinated graphite particles was incorporated into the epoxy resin film of the resin layer, and part of the particles was buried and fixed, and the center line average roughness Ra was 2 to 3 μm. Had. The obtained water-repellent film had a contact angle of water droplets of 165 ° and a contact angle of liquid paraffin of 110 °. The surface hardness measured by a pencil hardness tester was B.

[Example 5] In Example 1, instead of Cefrallube, Fluon powder (Fluoro 140) was used.
(Product name: Fluorocarbon resin powder manufactured by Asahi Glass Co., Ltd., melting point 32
7 ° C.) to obtain a water-repellent film in the same manner. The obtained water-repellent film is made of a resin layer, Lumiflon LF-200.
Part of the fluorine-based resin powder is taken into the coating film of C and partially buried and fixed, and the center line average roughness Ra is 2 to 3 μm.
m. The water-repellent film has a contact angle of water droplets of 156 ° and a contact angle of liquid paraffin of 110
Was ゜. The surface hardness measured by a pencil hardness tester was B.

Example 6 In Example 1, fluoron lubricant (L170J) was used in place of sefrallube.
A water-repellent coating was obtained in the same manner except that (trade name, fluororesin powder manufactured by Asahi Glass Co., Ltd., average particle diameter 0.2 μm, melting point 327 ° C.) was used. The obtained water-repellent film has a surface having a centerline average roughness Ra of 2 to 3 μm, in which a part of the fluonlubricant particles is incorporated in the resin layer Lumiflon LF-200C coating film and partially fixed. Had properties. The water-repellent film had a contact angle of water droplets of 156 ° and a contact angle of liquid paraffin of 120 °. The surface hardness measured by a pencil hardness tester was HB.

Comparative Example 1 A water-repellent coating was obtained in the same manner as in Example 1 except that the polyvinylidene fluoride resin powder was not used. In the obtained water-repellent coating, a part of the cefral-lube particles is taken in and fixed to a part of the resin layer Lumiflon LF-200C coating.
a had a surface characteristic of 2-3 μm. The water-repellent coating had a contact angle of water droplets of 156 ° and a contact angle of liquid paraffin of 120 °. However, the surface hardness measured by a pencil hardness tester was 6B, and the surface was easily scratched.

Comparative Example 2 A water-repellent coating was obtained in the same manner as in Example 1 except that no heat treatment was performed after the application of the particles. The resulting water-repellent coating is a resin layer of Lumiflon LF-2.
Some of the particles of the polyvinylidene fluoride resin and cefurallube were taken into the coating film of 00C and partially embedded and fixed, and had a center line average roughness Ra of 2 to 3 μm. The water-repellent coating had a contact angle of water droplets of 156 ° and a contact angle of liquid paraffin of 120 °. The surface hardness measured by a pencil hardness tester was 6B, which was the same as that in Comparative Example 1 using no polyvinylidene fluoride resin.

Comparative Example 3 A water-repellent coating was obtained in the same manner as in Example 1 except that an epoxy resin powder was used instead of the polyvinylidene fluoride resin powder. The obtained water-repellent coating has a surface characteristic of having a centerline average roughness Ra of 2 to 3 μm, in which a part of cefrallube particles is taken in and partially buried and fixed in a resin layer of Lumiflon LF-200C. I was The water-repellent film had a contact angle of water droplets of 156 ° and a contact angle of liquid paraffin of 120 °. The surface hardness measured by a pencil hardness tester was 6B.

[0026]

According to the present invention, a material having practical hardness and high water repellency can be easily obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 127/12 C09D 127/12 127/16 127/16 // C08L 101: 00 C08L 101: 00 (71) Applicant 000000044 Asahi Glass Co., Ltd. 1-12-1 Yurakucho, Chiyoda-ku, Tokyo (72) Inventor Kazuchika Hiromatsu 3-14-21 Shibaura, Minato-ku, Tokyo Inside TEPCO Environmental Engineering Co., Ltd. (72) Kiyosaku Kumai, Inventor 3-2-1-10 Chigasaki, Chigasaki-shi, Kanagawa Prefecture Inside Seimi Chemical Co., Ltd. (72) Inventor Akio Tokukai 1-14-50-305, Iwata, Tsurumi-ku, Yokohama-shi, Kanagawa-ken (72) Inventor Katsuharu Ito, Yokohama-shi, Kanagawa 1150 Hazawacho, Kanagawa-ku Asahi Glass Co., Ltd. F-term (reference) 4D075 AE03 BB26Z CA02 CA36 EA02 EA23 EB16 EB17 4F006 AA12 AA17 AA18 AA34 AA37 AA38 AA42 A B19 BA11 CA00 CA04 CA06 CA08 DA04 EA05 4J038 CD111 CD122 CD152 JA03 JA18 JA25 KA06 MA02 MA07 MA10 MA12 NA01 NA07 NA11 PA18 PA19 PC08

Claims (3)

[Claims] The present invention is characterized in that a paint containing a solvent capable of swelling or dissolving the resin of the resin layer, polyvinylidene fluoride resin powder and a higher melting point fluororesin powder is applied to the surface of the resin layer, followed by heat treatment. Method for forming a water-repellent film. 2. The method for forming a water-repellent film according to claim 1, wherein the resin layer is formed by applying a paint containing a cold-setting resin. 3. The method for forming a water-repellent film according to claim 1, wherein the surface roughness of the water-repellent film is 1 to 5 μm in center line average roughness Ra.