JP2896613B2 - Method for producing water-repellent or lubricious coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a water-repellent or lubricating film having remarkable water repellency and lubricity.

[0002]

2. Description of the Related Art Conventionally, a composite plating solution in which a fluororesin such as polytetrafluoroethylene or fluorinated graphite is suspended in a plating solution such as a nickel plating solution or the like, and a fluororesin or fluorinated graphite is commonly used in a plating film. It is known that a fluororesin or fluorinated graphite dispersed composite plating film obtained by dispersing and dispersing it gives excellent water repellency and lubricity, and is used as a water repellency or lubricity film.

[0003]

However, there is a need for a coating that can provide even better water repellency and lubricity. That is, the contact angle of the conventional composite plating film in which polytetrafluoroethylene particles are dispersed is about 105 °, and the contact angle of the composite plating film in which fluorinated graphite is dispersed is 120 °.
High water repellency with a contact angle that exceeds this,
Further, development of a highly lubricating film has been demanded.

SUMMARY OF THE INVENTION The present invention has been made in response to the above-mentioned demands, and has as its object to provide a method for producing a water-repellent or lubricating film having remarkable water repellency and lubricity.

[0005]

The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a composite plating solution in which polytetrafluoroethylene oligomer particles having a molecular weight of 10,000 or less are dispersed in the plating solution. Forming a composite plating film in which the polytetrafluoroethylene oligomer particles are eutectoidally dispersed on the processing object, and further contacting a fluorine gas with the composite plating film as necessary. It was found that when the treatment was performed, a film having remarkable water repellency and lubricity was obtained.

That is, as described above, a composite plating film in which polytetrafluoroethylene particles are dispersed is known, but its contact angle is about 105 ° as described above. In this case, the polytetrafluoroethylene dispersion amount in the conventional polytetrafluoroethylene particle-dispersed composite plating film is usually 20 to 40% by volume, and if this dispersion amount is further increased, it is possible to improve water repellency to some extent. There is
There is a limit to the amount of dispersion. Even if the amount of dispersion can be increased without limit, there is a limit to the increase in water repellency or contact angle, and a remarkably high water repellency or contact angle cannot be obtained. This can be recognized from the fact that the contact angle when a polytetrafluoroethylene film is formed on the entire surface as a so-called Teflon coating is about 110 °.

However, when composite plating is carried out by dispersing polytetrafluoroethylene oligomer particles having a molecular weight of 10,000 or less in a plating solution, the resulting composite plating film has an extremely high water repellency as compared with the prior art, For example, it is surprising that a contact angle of 173 ° can indeed be achieved, and because of the coating surface (20 to
It has been found that the ratio of the number of fluorine atoms to the total number of atoms existing at a thickness of about 40 angstroms) can be significantly increased as compared with the conventional case. That is, the molecular weight of conventional polytetrafluoroethylene particles is usually 1
Even if the end of the chain has a CF ₃ bond, it is substantially composed of only CF ₂ groups, so that the dispersion amount of the polytetrafluoroethylene particles is increased. However, the number of fluorine atoms on the surface does not increase so much. Even if the entire surface is covered with the polytetrafluoroethylene particles, the ratio of the number of fluorine atoms on the surface is about 15%, while the polytetrafluoroethylene having a molecular weight of 10,000 or less is used. When composite plating is performed using oligomer particles, the obtained film has a considerable amount of CF ₃ groups, and can form a film having a ratio of surface fluorine atoms of 40% or more,
It has been found that this makes it possible to obtain a film that is extremely rich in water repellency and lubricity.

Hereinafter, the present invention will be described in more detail. The method for producing a water-repellent or lubricating film of the present invention is carried out using a composite plating solution in which polytetrafluoroethylene oligomer particles having a molecular weight of 10,000 or less are dispersed in the plating solution. The processing object is plated to form a composite plating film in which the polytetrafluoroethylene oligomer particles are eutectoidally dispersed on the processing object.

The polytetrafluoroethylene oligomer particles having a molecular weight of 10,000 or less used herein have a larger number of chain ends than conventional polytetrafluoroethylene having a molecular weight of 100,000 or more, and have a large number of CF ₃ groups existing at these ends. Therefore, a film having a high ratio of the number of fluorine atoms on the surface can be formed. The average particle size of the polytetrafluoroethylene oligomer particles is 0.1 to 150 μm, particularly 1 μm.
However, it is preferable to use as fine particles as possible from the viewpoint of increasing the ratio of the number of surface fluorine atoms.

As the plating solution for dispersing the polytetrafluoroethylene oligomer particles, a known plating solution used for composite plating can be used. In this case, either an electroplating solution or an electroless plating solution may be used. An electroplating solution can be used. Electroplating solutions include nickel plating solutions such as Watt bath and nickel sulfamate bath, as well as nickel alloy plating solutions, copper plating solutions,
Copper alloy plating solutions and the like can be used, and those having a known bath composition can be used.

The amount of polytetrafluoroethylene oligomer particles dispersed in these plating solutions is 1 to 300 g / g.
1 but preferably 10 to 100 g / l.

In this case, a surfactant may be added to these plating solutions in order to make the dispersion of the polytetrafluoroethylene oligomer in the solution uniform or to increase the amount of eutectoid in the plating film. As the surfactant, one or more kinds of perfluoroalkyl-based surfactants can be used, and a cationic perfluoroalkylammonium salt is particularly preferred. The addition amount of these surfactants is preferably 0.001 to 10 g / l, particularly preferably 0.01 to 1 g / l.

The conditions for performing the composite plating using the above plating solution may be the usual conditions for the plating solution, but the polytetrafluoroethylene oligomer particles are dispersed in the plating solution as uniformly and as non-aggregated as possible. ,
In order to increase the eutectoid content of the particles in the plating film, and to uniformly disperse and combine single particles in the plating film, it is preferable to perform sufficient stirring. For example, ultrasonic stirring is recommended.

According to the present invention, a fluorination treatment in which a fluorine gas is brought into contact with the composite plating film obtained as described above, if necessary, can be adopted.
Lubricity can be improved. In particular, when the heat treatment is performed in the presence of oxygen, the contact angle is slightly reduced, and it is considered that the fluorine in the particles is replaced by oxygen. It is substituted by fluorine, the ratio of the number of surface fluorine atoms increases, and the contact angle increases.

The water-repellent, lubricating film obtained by the method of the present invention has a surface fluorine atom ratio in the case of using conventional polytetrafluoroethylene particles having a molecular weight of 100,000 or more. Although it is higher than about 15%, in this case, the ratio of the number of surface fluorine atoms is 40%.
%, More preferably 40 to 60%. Further, the dispersed complex amount of the polytetrafluoroethylene oligomer particles in the coating is 2 to 50% by volume, particularly 10 to 10% by volume.
It is preferred to be 25% by volume.

The water-repellent and lubricating film used in the present invention has excellent water-repellent and lubricating properties, and is therefore suitably used for various applications requiring such properties.

[0017]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Embodiment] A test piece (30 mm long, 30 mm long) was prepared using an electric composite nickel plating solution having the following composition under the following conditions.
(30 mm wide, 0.1 mm thick)
A water-repellent, lubricious film was obtained. Plating solution composition / plating conditions Nickel sulfamate 350 g / l Nickel chloride 45 g / l Boric acid 40 g / l Surfactant (* 1) 0.5 g / l Polytetrafluoroethylene oligomer particles (* 2) 50-70 g / l pH 3.7 Cathode current density 5 A / dm ² Anode Nickel plate Temperature 43 ° C. Stirring Ultrasonic plating time 10 minutes Film thickness 10 μm (Note 1) Megafac F-150 (manufactured by Dainippon Ink and Chemicals) ~ 10000, average particle size 4μm (Central Glass Co., Ltd.)

Next, the ratio of the number of fluorine atoms on the surface and the contact angle of the plating film obtained by the above composite plating method were measured by the following methods. Table 1 also shows the amount of eutectoid of the polytetrafluoroethylene oligomer particles. Method for measuring the ratio of the number of fluorine atoms The ratio of the number of fluorine atoms on the surface was measured by photoelectron spectroscopy. The equipment used was a Shimadzu X-ray photoelectron spectrometer ESCA
-750, and Mg-Kα (12530) as an X-ray source.
6 eV). The binding energy was corrected based on the gold 4f3 / 2 spectrum (83.6 eV), and each spectrum was measured and quantified. Contact angle measurement method Contact angle measurement is performed using a contact angle measuring device (G-
(Type 1) at room temperature. For the measurement, a drop of distilled water having a uniform diameter of 1 mm was dropped from a microsyringe with a microhead onto a sample, and the equilibrium contact angle was quickly read. The value of the contact angle was determined by the average value of ten measurement results.

[0020]

[Table 1]

[Comparative Example] In the composite plating using ordinary polytetrafluoroethylene powder (molecular weight of 100,000 or more) in place of the polytetrafluoroethylene oligomer particles in the plating solution of the example, the ratio of the number of fluorine atoms on the surface was 16%, eutectoid content 30% by volume, contact angle 105 °
Met.

[0022]

According to the present invention, a water-repellent or lubricating film excellent in water repellency and lubricity can be produced simply, reliably and with good reproducibility.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C25D 15/02 C23C 18/52

Claims (2)

(57) [Claims] 1. A composite plating film in which an object to be treated is plated with a composite plating solution in which polytetrafluoroethylene oligomer particles having a molecular weight of 10,000 or less are dispersed in a plating solution, and the polytetrafluoroethylene oligomer particles are eutectoidally dispersed. Is formed on the object to be treated. 2. A method for producing a water-repellent or lubricious film, comprising subjecting the composite plating film formed by the method of claim 1 to a fluorination treatment in which fluorine gas is contacted.