JP3489572B2 - Super water repellent film and method for producing the same - Google Patents

Description

BACKGROUND OF THE INVENTION DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a plastic film arm with enhanced functionality, among other things, relates to water repellent <br/> fill arm . [0002] In order to obtain a surface having water repellency, it is necessary to make the surface tension lower than the surface tension of water. There is a concept of a contact angle as a number indicating the water repellency, that is, the wettability of the material surface. When a water droplet is placed on the surface, it is the angle at which the water droplet contacts the surface. In general, a film having water repellency needs to be in a super water repellent state with a contact angle of water close to 160 ° in practical use. [0003] As a conventional film having water repellency and transparency, a film such as fluorine-based ethylene tetrafluoride-propylene hexafluoride copolymer resin (FEP) is typical. In recent years, it has been common practice to impart water repellency by applying a water repellent coating agent (for example, a fluorine-based coating agent) on the surface of a general-purpose film such as a polyester film. [0004] However, although the conventional fluorine-based film can provide transparency, the water repellency cannot be sufficiently satisfactory as the contact angle of water is about 100 °. . Not only that, but it is not practical in terms of cost. In order to cope with this cost reduction, a method of imparting functionality to the film surface by coating a general-purpose film as described above with a water-repellent coating agent has been adopted. However, although the cost is improved, the water repellency is about the same as that of the fluorine-based film, and the environmental resistance is inferior. Recently, not only films but also methods for improving water repellency include using a coating material of a composite paint in which inorganic fine particles are uniformly dispersed in a fluorine-based resin, silicone-based resin, etc., or using fine particles of fluorine resin in a nickel plating solution. There is a method of dispersing and plating. With these methods, a super-water-repellent state with a contact angle of water close to 160 ° has been obtained due to the morphological effect of the coated surface, but the adhesion to the film is weak even when applied on a film. Problems such as the inability to maintain the transparency of the device. Therefore, there has been a demand for a water-repellent film which maintains the transparency of the film and has a super-water repellency and which can be used practically at low cost. [0005] The present invention SUMMARY OF THE INVENTION In order to achieve the above object, silane-based fluorine formed and on its plastic film plastic film formed with fine projections on one side or both sides And a chemical adsorption film of the compound. The super-water-repellent film of the present invention is only subjected to a plasma treatment containing oxygen on the surface of the film to form projections of about 100 nm, thereby obtaining a surface morphological effect of improving water repellency. In addition, since the formed protrusions are about 100 nm, transparency can be maintained, and the surface treatment also provides reactive groups required by the chemisorbed monolayer formed thereon. In addition, the film and the chemically adsorbed monomolecular film can easily obtain a strong adhesive force, and are excellent in environmental resistance, life, and cost. The present invention will be described in Example 1 with reference to the drawings, taking water repellency and transparency as examples. (Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a structural view of the super water-repellent film of the present invention. FIG. 2 is an enlarged view of part B of FIG. 1 to the molecular level. In FIG. 1, 1 is a polyester film having a thickness of 0.1 mm, and 2 is a polyester film 1 having a height of 85 nm formed by performing a plasma treatment with oxygen gas.
The fine projections 3 on the polyester surface are chemical adsorption films made of a fluorine-containing chlorosilane compound (Chemical Formula 1). [0011] First, a procedure for producing a super water-repellent film will be described. First, the polyester film 1 is subjected to a plasma treatment of 0.2 W / cm2 for 5 minutes in a vacuum vessel having an oxygen partial pressure of 10 Pa. As a result, as shown in FIG. 1, minute projections having a height A from the film surface to the tip of 85 nm are formed, and at the same time, the film surface is hydrophilized. The polyester film 1 thus treated is taken out of the container and diluted with a solvent of cyclohexane to 1 × 10 −2 Mol.
immersion in a solution of a fluorine-containing chlorosilane-based compound (chemical formula 1) at a concentration of 1 / l for 10 minutes. Since the surface of the polyester is hydrophilized by the oxygen plasma treatment, the bond of the chemical formula (2) is formed on the surface, and the adsorption film 3 composed of the monomolecular film 4 of the fluorine-containing chlorosilane-based compound (chemical formula 1) is formed. You. (FIG. 2) In order to evaluate the water repellency and the transparency of the super water repellent film thus produced, the contact angle of water and the transmittance were measured. As a comparative sample, an FEP film, a polyester film coated with a fluorine-based resin, a polyester film coated with a composite paint in which inorganic fine particles (silica) are uniformly dispersed in a silicone-based resin, the same fluorine as the present invention without forming protrusions on the surface Using the four polyester films that have formed a chemisorption film using a chlorosilane-based compound,
The transmittance was measured. The film thicknesses are all 0.1 mm. The measurement results are shown in (Table 1). [Table 1] As is clear from Table 1, the super water-repellent film produced in Example 1 is a functional film excellent in both water repellency and transparency. (Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described. The procedure for producing the super water-repellent film will be described with reference to the drawings. FIG. 3 is a schematic view of a chemical adsorption film forming apparatus for producing the super water-repellent film of the present invention. In FIG. 3, 5 is a vacuum vessel, 6 is a fluorine-containing chlorosilane-based compound (chemical formula 1) contained in a closed vessel, 7
Is a cock of a closed container. After performing the same plasma treatment as in Example 1 to form minute projections on the film surface, the inside of the vacuum container was
Exhaust until 10-3Pa. Next, the cock 7 of the closed container is opened, and the stock solution of the chlorosilane-based compound 6 containing fluorine is vaporized. Then, since the surface of the film subjected to the plasma treatment is hydrophilized, a bond of (Chemical Formula 2) is formed between the vaporized (Chemical Formula 1) and the film surface, and the monomolecular film 4 of the fluorine-containing chlorosilane-based compound is formed. The adsorption film 3 is formed. The super water-repellent film thus produced was evaluated in the same manner as in Example 1. The measurement results are shown in (Table 2). [Table 2] As is clear from Table 2, the super water-repellent film produced in Example 2 is a functional film excellent in both water repellency and transparency, as in Example 1. At the same time, since film formation can be performed collectively in the same vacuum vessel, the process time can be reduced and the cost can be reduced. In Example 1 or 2, (Chemical Formula 1) was used as the chlorosilane-based compound, but other fluorine-containing chlorosilane-based compounds such as (Chemical Formula 3) and (Chemical Formula 4)
The same effect can be obtained by using such a method. Embedded image Embedded image In this embodiment, a chlorosilane compound is used as the compound to be adsorbed. However, the same effect can be obtained by using a methoxysilane compound, an ethoxysilane compound, or a mixed compound including a chlorosilane compound. be able to. The height of the projections on the film surface was 85 nm in this case. However, if the height is less than 10 nm, sufficient water repellency cannot be obtained. , Preferably 10-5
00 nm. In Example 2, the evaporation of the chlorosilane-based compound becomes difficult when the molecular weight of the chlorosilane-based compound is increased, that is, when the number of carbons is increased. And the number of carbons is preferably up to about 25. Further, although a polyester film is used in this embodiment, it goes without saying that a similar result can be obtained with other plastic films. The invention as described above, according to the present invention, by forming a chemically adsorbed film of one side or silane-based fluorine compounds form minute projections on both sides, with a transparent and had excellent water repellency Functional films can be easily and inexpensively provided, and the industrial and practical effects are enormous.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural view of a super-water-repellent film in Examples 1 and 2. FIG. 2 is an enlarged view of a portion B in FIG. FIG. 3 is a schematic diagram of a method for forming a chemically adsorbed film in Example 2. [Description of References] 1 Polyester film 2 Fine protrusions formed by plasma treatment 3 Formed by monomolecular film of fluorine-containing chlorosilane-based compound Chemically adsorbed film 4 Chemically adsorbed monomolecular film 5 Vacuum container 6 Fluorine-containing chlorosilane compound in closed container 7 Cock of closed container

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 7/00 C08J 7/06

Claims (1)

(57) [Claims 1] A plasma treatment using a gas containing at least oxygen on one or both surfaces of a plastic film.
Small projections with a height from the surface of 10 to 500 nm
A super water-repellent film formed by forming a chemically adsorbed monomolecular film of a silane-based fluorine compound along the fine projections .