JPH0625449A - Super water-repellent film and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Purpose] Conventionally, as water-repellent films, there have been fluorine-based plastic films, and plastic films coated with a fluorine-based or silicone-based water-repellent coating material on one or both sides. However, there were problems that practical water repellency could not be obtained and that the transparency of the film could not be obtained. In order to solve this problem, it is an object of the present invention to provide a functional film which maintains transparency and has super water repellency and which can be put to practical use at low cost. [Structure] A chlorosilane-based or alkoxysilane-based fluorine compound is chemically adsorbed on a plastic film on one or both sides of which appropriate minute protrusions have been formed by plasma treatment to form a monomolecular film, which has good transparency. A super water-repellent film is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic film having enhanced functionality and a method for producing the same, and more particularly to a water repellent film and a method for producing the same.

[0002]

2. Description of the Related Art In order to obtain a water-repellent surface, it is necessary to make its surface tension lower than that of water. There is a concept of contact angle as a number indicating water repellency, that is, the wettability of a material surface. The angle at which the surface of the water drops contacts the surface when the water drop is placed on the surface. Generally, as a film having water repellency, a super water repellent state in which the contact angle of water is close to 160 ° is practically required.

As a conventional film having water repellency and transparency, a film of fluorine-based tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP) or the like is typical. In addition, recently, it has been generally practiced to impart water repellency by coating a surface of a general-purpose film such as a polyester film with a water repellent coating agent (for example, a fluorine-based coating agent).

[0004]

However, although the conventional fluorine-based film can provide transparency, it does not have sufficient water repellency such that the contact angle of water is about 100 °. Not only that, but also in terms of cost, it is not practical. In order to cope with this cost reduction, there has been adopted a method of imparting functionality to the film surface by coating the above-mentioned general-purpose film with a water-repellent coating agent. 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 film, but also as a method of improving water repellency, a method of using a composite paint in which inorganic fine particles are uniformly dispersed in a fluororesin, a silicone resin, etc. as a coating agent, or fine particles of a fluorine resin in a nickel plating solution are used. There is a method of dispersing and plating. When these methods are used, a super water-repellent state with a contact angle of water of about 160 ° is obtained due to the morphological effect of the coated surface, but even if it is applied on a film, the adhesion to the film is weak. There will be problems such as the inability to maintain transparency. Therefore, it has been desired to develop a water-repellent film that maintains the transparency of the film, has super-water repellency, and can be used practically at low cost.

[0005]

In order to achieve the above-mentioned object, the present invention provides a plastic film having minute projections formed on one side or both sides thereof, and a chlorosilane type, a methoxysilane type, and a chlorosilane type formed on the plastic film. Or a chemical adsorption film of an ethoxysilane fluorine compound.

[0006]

The super-water-repellent film of the present invention is not only provided with a surface morphological effect of improving water repellency by subjecting the surface of the film to plasma treatment containing oxygen to form protrusions of about 100 nm, and Since the protrusions formed have a thickness of about 100 nm, transparency can be maintained, and the surface treatment also imparts the reactive groups required by the chemisorption monomolecular film formed thereon, and thus the film is A strong adhesion force can be easily obtained with the chemisorption monomolecular film, which is excellent in environmental resistance, life, and cost.

[0007]

EXAMPLE The water repellency and transparency of the present invention will be described as an example to explain Example 1 with reference to the drawings.

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a constitutional 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 height of 85 nm formed by subjecting the polyester film 1 to plasma treatment with oxygen gas.
The minute projections 3 on the polyester surface are a chemical adsorption film made of a fluorine-containing chlorosilane compound (Chemical formula 1).

[0011]

[Chemical 1]

First, the procedure for producing the super water repellent film will be described. First, the polyester film 1 is plasma-treated at 0.2 W / cm ² for 5 minutes in a vacuum container 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 made hydrophilic. The polyester film 1 thus treated was taken out of the container and diluted with a solvent of cyclohexane to give 1 × 10 ^-2 Mol.
Immerse in a solution of a fluorine-containing chlorosilane compound (Chemical Formula 1) having a concentration of / l for 10 minutes. Since the surface of the polyester is hydrophilized by oxygen plasma treatment, the bond of (Chemical Formula 2) is formed on the surface, and the adsorption film 3 consisting of the monomolecular film 4 of the chlorosilane compound containing fluorine (Chemical formula 1) is formed. It (Fig. 2)

[0013]

[Chemical 2]

In order to evaluate the water repellency and transparency of the super water repellent film thus formed, the contact angle of water and the transmittance were measured. As comparative samples, a FEP film, a polyester film coated with a fluorine-based resin, a polyester film coated with a composite coating 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 The same as the contact angle of water, which was obtained by using four polyester films on which a chemical adsorption film was formed using a chlorosilane-based compound.
The transmittance was measured. The film thickness is all 0.1 mm.

The measurement results are shown in (Table 1).

[0016]

[Table 1]

As is clear from this (Table 1), the super water-repellent film produced in Example 1 is a functional film excellent in both water repellency and transparency.

(Second Embodiment) A second embodiment of the present invention will be described below.

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 container, 6 is a fluorine-containing chlorosilane compound (Chemical formula 1) contained in a closed container, 7
Is a cock of a closed container.

The same plasma treatment as in Example 1 was performed to form minute protrusions on the film surface, and then the inside of the vacuum chamber was 1 ×.
Evacuate to 10 ^-3 Pa. Next, the cock 7 of the closed container is opened to vaporize the stock solution of the chlorosilane compound 6 containing fluorine. Then, since the surface of the film subjected to the plasma treatment is made hydrophilic, 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 compound is formed. The adsorption film 3 is formed.

The super water-repellent film thus obtained was evaluated in the same manner as in Example 1. The measurement results are shown in (Table 2).

[0022]

[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 it is possible to collectively form a film in the same vacuum container, it is possible to shorten the process time and reduce the cost.

Although (Chemical Formula 1) was used as the chlorosilane-based compound in Example 1 or 2, other fluorine-containing chlorosilane-based compounds such as (Chemical Formula 3) and (Chemical Formula 4) were used.
The same effect can be obtained by using, for example.

[0025]

[Chemical 3]

[0026]

[Chemical 4]

In this embodiment, a chlorosilane compound is used as the compound to be adsorbed, but a similar effect can be obtained even if a methoxysilane compound, an ethoxysilane compound, or a mixed compound including a chlorosilane compound is used. be able to.

The height of the projections on the film surface was 85 nm this time, but if the height is 10 nm or less, sufficient water repellency cannot be obtained, and if it exceeds 500 nm, the mechanical strength of the film surface becomes weak as much as possible. , Preferably 10-5
It is 00 nm.

In Example 2, when the molecular weight of the chlorosilane compound becomes large, that is, when the number of carbons becomes large, it becomes difficult to evaporate, but it can be dealt with by heating the stock solution appropriately, but in the case of a straight chain Therefore, it is desirable that the number of carbons is up to about 25.

Further, although the polyester film is used in this embodiment, it goes without saying that the same result can be obtained with other plastic films.

[0031]

As described above, the present invention forms a chemical adsorption film of a chlorosilane-based, methoxysilane-based, and / or ethoxysilane-based fluorine compound on a plastic film having minute protrusions formed on one or both sides. As a result, a transparent functional film having excellent water repellency can be easily provided at low cost, and industrial and practical effects are great.

[Brief description of drawings]

FIG. 1 is a structural diagram of superhydrophobic films in Examples 1 and 2.

FIG. 2 is a cross-sectional view obtained by enlarging the portion B in FIG. 1 in Examples 1 and 2 to a molecular level after forming a film.

FIG. 3 is a schematic diagram of a method for forming a chemisorption film in Example 2.

[Explanation of symbols]

1 Polyester film 2 Micro projections formed by plasma treatment 3 Chemical adsorption film formed by monomolecular film of chlorosilane compound containing fluorine 4 Chemically adsorbed monomolecular film 5 Vacuum container 6 Fluorine-containing chlorosilane in closed container -Based compound 7 Cock for closed container

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08J 7/00 306 7310-4F C09K 3/18 104 8318-4H

Claims (6)

[Claims] 1. A super-repellent film comprising a plastic film having minute projections formed on one or both sides and a chemical adsorption film of a chlorosilane-based, methoxysilane-based, or ethoxysilane-based fluorine compound formed on the plastic film. Aqueous film. 2. The super water-repellent film according to claim 1, wherein the minute projections are formed by plasma treatment with a gas containing at least oxygen. 3. The water-repellent film according to claim 1, wherein the height of the minute projections from the film surface is 10 to 500 nm. 4. A plastic film is plasma-treated on one or both sides with a gas containing at least oxygen,
A step of uniformly and minutely roughening the surface of the plastic film, and immersing the plastic film in a solution containing at least one chlorosilane-based, methoxysilane-based, or ethoxysilane-based fluorine compound, and adding the fluorine-based compound to the solution. Method for producing a super water-repellent film, which comprises a step of chemically adsorbing with water 5. A plasma treatment is performed on one or both sides of a plastic film with a gas containing at least oxygen,
Step P for uniformly and minutely roughening the surface of the plastic film, and at least one chlorosilane-based, methoxysilane-based, or ethoxysilane-based fluorine compound or a solution of a fluorine compound diluted with a solvent is chemically adsorbed on the plastic surface by the gas phase. A method of manufacturing a super water-repellent film, which comprises the step of: 6. The method for producing a super water-repellent film according to claim 5, wherein the step P and the step Q are collectively performed in the same vacuum container.