JPH11256339A - Water-repellent coating film, antifouling article, and method for producing water-repellent coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating film comprising an SiO ₂ film provided with water repellency, a method for producing the same, and S provided with water repellency.
An article having an iO ₂ film as an antifouling surface is provided. SOLUTION: When a SiO ₂ film is formed by a CVD method so as to leave a CH ₃ group and / or a C ₂ H ₅ group, a water-repellent coating film is obtained. Desirably, the film thickness is 10 mm or more,
And the contact angle with water is 90 ° or more. A monomer material containing a Si atom and a CH ₃ group or a C ₂ H ₅ group, and a mixed gas containing an oxygen gas are mixed at a ratio of 10 parts by weight to 1000 parts by weight of an oxygen gas with respect to 100 parts by weight of the monomer material.
It is introduced into a vacuum chamber, and a thin film of an SiO ₂ film in which CH ₃ groups and / or C ₂ H ₅ groups remain is formed on a substrate by a CVD method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating film obtained by imparting water repellency to an SiO ₂ film, a water repellent coating film for imparting antifouling property to an article surface, and a method for producing the same.
In particular, the present invention relates to a method for producing a water-repellent coating film that does not affect the optical properties of an optical article.

[0002]

2. Description of the Related Art Conventionally, a coating film for imparting water repellency to the surface of an article is generally formed by wet coating a fluororesin, which is called a so-called water repellent coating film. The surface imparted with water repellency has a function as an antifouling surface because dirt is difficult to reach.

[0003] Conventional fluorine-based resin materials as materials for water-repellent coating are expensive, and are formed on the outermost surface of a high-value-added product, for example, an antireflection film provided in a high-end model of a computer display. It has been used for antifouling coats. In particular, in an antifouling coat formed on the outermost surface of an antireflection film used on the surface of an optical article such as a computer display, in order not to affect the optical properties of the laminated antireflection layer, a very Therefore, it was necessary to form a thin film uniformly, requiring a high technology, and the yield was not high.

In addition, it is necessary to use a fluorine-based solvent which has a bad influence on the environment as a fluorine-based resin formed by wet coating, and it is necessary to introduce an expensive apparatus for a solvent recovery treatment. Further, the use of a fluorine-based solvent may be restricted in the future, and a water-repellent coating that does not use a fluorine-based solvent is desired.

[0005] In the processing step of the antireflection film, the antireflection layer is generally formed by a vacuum film forming step such as a CVD method or a vapor deposition method. In such a case, there is a problem that the production loss of the setup change is large.

Generally, a SiO _X film is hydrophilic. Also,
The SiO _x film produced by the conventional CVD method has excellent uniformity and safety, but does not have high water repellency.

[0007]

Accordingly, a first object of the present invention is to provide a coating film comprising a water-repellent SiO ₂ film. A second object of the present invention is to provide a water-repellent coating film. To provide an article having a coating film made of a SiO ₂ film as an antifouling surface, and a third object of the present invention is to provide a method for producing a coating film made of a SiO ₂ film provided with water repellency. is there.

[0008]

In order to achieve the first object, the present invention provides a water repellent SiO ₂ film formed by a CVD method so as to leave a CH ₃ group and / or a C ₂ H ₅ group. It is a water-repellent coating film characterized by the following. The water-repellent coating film of the present invention preferably has a thickness of 1
0 ° or more, and the contact angle with water is 90 ° or more.

In order to achieve the second object, the present invention provides an antifouling article having as a coating film a SiO ₂ film containing CH ₃ groups and / or C ₂ H ₅ groups and having increased water repellency. It is.

[0010] In order to achieve the third object, the present invention provides a method for producing a mixture of a monomer material containing a Si atom and a CH ₃ group and / or a C ₂ H ₅ group, and a mixed gas containing an oxygen gas with 100 parts by weight of the monomer material. 10 parts by weight to 100 parts by weight of oxygen gas
In a proportion of 0 part by weight, SiO ₂ which is introduced into a vacuum chamber, CH ₃ groups and / or C ₂ H ₅ group remained by CVD
A method for producing a water-repellent coating film, comprising forming a thin film on a substrate. If a material containing a methyl group or an ethyl group is used and this is not formed by the CVD method,
No methyl or ethyl groups can be introduced into the membrane.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The conditions for introducing a methyl group and / or an ethyl group by the CVD method are as follows. In addition to using the above-mentioned materials, a monomer containing a Si atom and a CH ₃ group and / or a C ₂ H ₅ group is used. The composition ratio of the material and the mixed gas containing the oxygen gas is set such that the oxygen gas 10
Parts by weight to 1,000 parts by weight. Oxygen gas with less than 10 parts by weight can not form a SiO ₂ film, and the oxygen gas is more than 1,000 parts by weight SiO ₂
It is not preferable because a methyl group or an ethyl group is not contained in the film and water repellency is lost. Further, in order to exhibit water repellency, the thickness of the water repellent coating film must be at least 10 ° or more. If the thickness of the water-repellent coating film is less than 10 °, it does not exist as a continuous film.

Regarding the effect of water repellency : The SiO ₂ coating film provided with water repellency according to the present invention has a low surface energy, is easy to repel oils and fats which are main components of stains such as fingerprints, and does not easily stain. In particular, when the contact angle with water is 90 ° or more, the antifouling effect of the SiO ₂ coating film increases.

For products requiring antifouling property : The water repellent SiO ₂ coating film of the present invention is preferably provided with an antifouling coating on a surface which is conspicuous when a display member such as a computer display is contaminated. Can be used. In particular, a display member such as a computer display on which an antireflection layer is formed for antireflection requires an antifouling coat. Further, optical articles such as glasses and camera lenses dislike surface dirt, and thus require an antifouling coat. In other fields, antifouling surfaces are required in various fields such as interior members such as tiles and decorative plates, exterior members, automobile bodies, outdoor signs, and covers for outdoor lights. The water-repellent coating film of the present invention is effective as an antifouling surface film. Since antifouling property, that is, water repellency is a property of the surface, the film thickness of the antifouling coat does not need to be thick,
It is sufficient that the film thickness is at least 10 ° or more. Also, there is no need to control the film thickness. However, in the case of the above-described optical member, particularly a member subjected to an antireflection treatment, it is preferable to control the film thickness to 100 ° or less so as not to affect the optical characteristics. Further, in the case of a member that is severely worn, the film thickness may be made relatively thick to increase the durability.

About the monomer material used in the present invention,
Te: the monomeric material for forming the SiO ₂ film having water repellency by the CVD method of the present invention includes a methyl group or an ethyl group, and the Si as the main chain, monomeric materials such as the following, for example, HMDSO ( Hexamethyldisiloxane), TMDSO (tetramethyldisiloxane), octamethylcyclotetrasiloxane, TEOS (tetraethoxysilane), TMOS (tetramethoxysilane),
MTMOS (methyltrimethoxysilane), methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane, ethylsilane and the like are preferably used.

However, irrespective of the above-mentioned example, the monomer material forming the water repellent SiO ₂ film includes S
Any material may be used as long as it is an organic compound containing an i atom, a CH ₃ group and / or a C ₂ H ₅ group, has an appropriate vapor pressure at room temperature, and is capable of performing a CVD method. .

Using a material having a functional group having 3 or more carbon atoms such as a C ₃ H ₈ group, an SiO ₂ film containing the functional group is subjected to CVD.
It is thought that it is theoretically possible to form them by the method. However, in practice, the vapor pressure of these materials is very low, so that it is very difficult to form a SiO ₂ film.

Among the above monomer materials, HMDS
O, TMDSO, and octamethylcyclotetrasiloxane are particularly desirable as materials for forming the water-repellent SiO ₂ film. The reason is that in these siloxane materials, the CH ₃ group that expresses water repellency is directly bonded to Si atoms, not through Si—O bonds or OC bonds that are apt to be broken. This is because they are easily taken in stably.

SiO 2 provided with water repellency by CVD
_In order to form the _two films, it is necessary to introduce oxygen gas in addition to the above monomer material. Instead of oxygen gas, an oxidizing gas such as ozone gas or laughing gas (N
_{Although 2} O) and the like can be used, oxygen gas is most preferable in terms of film forming efficiency and cost.

In addition to the monomer gas and oxygen gas,
A gas (carrier gas) for efficiently introducing the monomer vapor into the vacuum chamber, a plasma, or a gas for the purpose of enhancing the plasma may be enhanced and introduced as needed.

A method of performing the CVD method : CV used in the present invention
There are several methods such as a thermal CVD method and a photo CVD method in the method D. The method of forming a water repellent SiO ₂ film is that low-temperature film formation is possible and material utilization efficiency is low. The plasma CVD method is optimal from the point of view.

The most general method of the plasma CVD method is a method of applying a 13.56 MHz electric field between parallel plate electrodes. That is, a constant pressure (for example, 50 mTorr) is introduced by introducing a source gas into the vacuum chamber.
r), between the plate electrode placed in the vacuum chamber and the ground electrode placed parallel to and opposed to the plate electrode.
An RF AC voltage of 56 MHz is applied (for example, 500
300 W of power is applied to the electrode area of ² cm ² )
As a result, glow discharge plasma is generated, and the source gas is chemically reacted by using the plasma flow to form a SiO ₂ film having water repellency. The substrate for depositing the film is usually placed on the surface of the earth electrode.
It is also possible to install it on the plate electrode side to which F power is applied.

In the method of manufacturing a water repellent SiO ₂ film, the applied RF AC voltage is 13.5.
Lower frequency (40 kHz or 5
0 kHz) or a higher frequency (2.
45 GHz or the like can be applied. Also,
It is also possible to apply a DC voltage. Instead of the flat plate electrode, a hollow cathode electrode that generates a plasma flow by blowing gas may be used, or induction plasma may be generated from an external coil. It is also possible to increase the plasma density by using a magnetic field or by using an ECR resonance phenomenon (a phenomenon in which electrons in the plasma undergo cyclotron resonance by appropriately adjusting the electric and magnetic fields).

Regarding the film forming conditions of the CVD method, the film forming conditions of the CVD method include input power, gas flow rate, film forming pressure, and the like in addition to the CVD method (input power frequency, electrode structure, etc.).
Although there are various parameters such as the distance between the electrodes, it is the flow rate ratio between the monomer and oxygen gas that has an effect on the water repellency. That is, when the monomer is large relative to the oxygen, because the CH ₃ group which can not react to remain in the film, but exhibits high water repellency, the CH ₃ group if sufficient oxygen is supplied All are decomposed, and the CH ₃ group is not present in the film, and the contact angle with water becomes low.

For example, when HMDSO is used as a raw material, in an ideal state where all the raw materials are SiO ₂ , CO ₂ and H ₂ O, 1200 parts by weight of oxygen gas is required for 100 parts by weight of HMDSO. It is. However, even if the CVD method is performed with such a quantitative ratio, an intermediate reactant (for example, CH ₃ OH or HCHO) is actually generated, or the material itself is exhausted. Conversely, oxygen that could not react may be exhausted, so that the ratio between the monomer material and the oxygen gas required for the CVD method does not follow the chemical formula.

According to various experimental results in the present invention, the flow rate ratio between the monomer material and the oxygen gas is such that when the amount of the oxygen gas is 1000 parts by weight with respect to 100 parts by weight of the monomer material, the contact angle with water is about 90 degrees. It becomes a water-repellent coating film necessary for exhibiting antifouling properties. If the flow rate of oxygen gas is further increased, the contact angle with water decreases, and if the flow rate of oxygen gas is further reduced, the contact angle increases.

In obtaining these results, the contact angle of SiO ₂ to water obtained in relation to the flow rate ratio between the monomer material and oxygen gas was tested.
Got a relationship.

[0027]

[Table 1] Confirmation of CH ₃ group : The presence of a CH ₃ group bonded to a Si atom can be confirmed by IR spectroscopy. That is, the peak appearing around 1280 cm ^{-1 in the} IR spectroscopy spectrum is attributable to the Si—CH ₃ stretching vibration, and the presence of this peak confirms the presence of the CH ₃ group.
The measurement method is as follows.
An O ₂ film is formed with a thickness of 1000 to 2000 ° and measured by an IR spectrometer.

FIG. 1 is a graph showing the IR spectrum when the ratio of the monomer oxygen of the source gas at the time of film formation is 1: 5, FIG. 2 is 1:10 and FIG. 3 is 1:20.
In FIG. 1, the peak around 1280 cm ⁻¹ is very large, but in FIG. 2, it is small, and in FIG.
No peak near cm ^-1 can be confirmed.

[0029]

The present invention will be described below in detail with reference to examples. The embodiments described in the following description are merely preferred examples within the scope of the present invention. Therefore, the present invention is not limited only to the embodiments described below.

Example 1 Confirmation of Water Repellency A silicon wafer (4 inch φ, P type 0.2 Ωcm) was placed as a base material in a parallel plate type plasma CVD apparatus PE401 (manufactured by Anelva Co., Ltd.). The ultimate degree of vacuum before film formation was set to 0.02 mTorr, Ar gas was used as a carrier gas, and oxygen and HMDSO (hexamethyldisiloxane) were bubbled at room temperature as source gases and supplied into the apparatus.

The flow rate of the oxygen gas is 30 sccm, and
The Ar gas flow rate was adjusted so that the flow rate of the monomer was 6 sccm. So that the film forming pressure is 50 mTorr,
The conductance valve was adjusted.

Plasma was generated by applying a power of 100 W and 13.56 MHz between the upper plate electrode and the lower ground electrode. The substrate is placed on the lower ground electrode,
An SiOx film was formed. The deposition time was 10 minutes. It was confirmed by ellipsometry that a SiOx film of about 1000 ° was formed.

The presence of the CH ₃ group was confirmed by IR spectroscopy. The evaluation method was evaluated using a contact angle with water. For comparison, an oxygen gas flow rate of 30 sccm, a monomer flow rate of 1.5 sccm, and a film having no CH ₃ group were prepared and evaluated. As a result, the former contact angle was 110 degrees, while the latter contact angle was 55 degrees.

Example 2 As a base material for forming a water-repellent layer on an antireflection film , a PET film (Toray, Lumirror T-6) was used.
0, a thickness of 100 μm, and a width of 660 mm), the following four-layered antireflection layer was formed by vacuum winding sputtering.

The first layer ITO: 125 Å; a second layer SiO _2: 250 Å; third layer ITO: 1000 Å; fourth layer SiO _2: 800 Å.

Since the SiO ₂ film formed here is formed by a sputtering method, it has a strong hydrophilicity, does not have water repellency, and has no antifouling property. An antifouling SiO ₂ film was formed on the thus prepared raw material by a CVD method. The CV
The apparatus used in the method D includes a vacuum winding device (CVD)
Was used. The ultimate pressure of the chamber is 0.05 mTorr
Then, a raw material gas composed of oxygen gas and HMDSO was introduced therein, and the pressure was set to 45 mTorr. The flow rate of the introduced raw material gas was 10 slm for oxygen gas and 2 for HMDSO.
slm.

For HMDSO, a gas supply system heated to 80 ° C. was used, and no carrier gas was used. The film forming drum is -10 to eliminate thermal damage to the film substrate.
Cooled down every time. A flat plate electrode at a position facing the film forming drum (a distance of 3 cm from the film forming drum, an electrode area of 70 c)
An RF AC voltage of 13.56 MHz was applied (1.5 kW) to the film forming drum, and plasma was generated between the film and the electrically grounded film forming drum to form a film on the substrate. The running speed of the film was 30 m / min.

The antireflection film with an antifouling coat prepared in this manner was used in Example 2 except that the antireflection film without the antifouling coat, that is, the CVD film was not formed.
A comparison was made between the film produced under the same conditions and the antireflection properties, but there was no difference between the two. That is, even if an antifouling coat was formed on the antireflection film by the CVD method, the antireflection characteristics were not impaired.

The antireflection film with an antifouling coat obtained in Example 2 was hardly stained, and dirt such as fingerprints could be easily wiped off. Fingerprints were easily formed and dirt could not be removed by wiping.

[0040]

The water-repellent coating film of the present invention has a CV
Since it is manufactured by the method D, it is more uniform than conventional water-repellent films made of a fluorine-based resin or a silicon resin and does not generate harmful substances at the time of manufacture, so that it is safe. As a secondary effect, a higher film forming speed is realized as compared with normal film forming, for example, a vapor deposition method.

The water-repellent coating film obtained by the present invention is not only a water-repellent SiO ₂ film but also a S
Since it is an iO ₂ film, it becomes a hard coat film. Therefore, compared to the conventional water repellent film of an organic polymer compound, SiO 2
_{2. The} film is hard, so it is hard to be scratched and can have an antifouling surface.

[Brief description of the drawings]

FIG. 1 shows that the ratio of monomer oxygen in a source gas during film formation is 1: 5.
It is a graph which shows IR spectrum when it is.

FIG. 2 shows that the ratio of monomer oxygen in the source gas during film formation is 1: 1.
It is a graph which shows IR spectrum when it is 0.

FIG. 3 shows that the ratio of monomer oxygen in the source gas during film formation is 1: 2.
It is a graph which shows IR spectrum when it is 0.

Claims (4)

[Claims] 1. A water-repellent coating film which is a water-repellent SiO ₂ film formed by a CVD method so as to leave a CH ₃ group and / or a C ₂ H ₅ group. 2. The water-repellent coating film having a thickness of 10
The water-repellent coating film according to claim 1, wherein the contact angle with water is 90 ° or more. 3. An antifouling article having the water-repellent coating film according to claim 1 on its surface. 4. A Si atom and a CH ₃ group and / or C ₂ H ₅
A monomer material containing a group and a mixed gas containing an oxygen gas,
Oxygen gas is introduced into the vacuum chamber at a ratio of 10 parts by weight to 1000 parts by weight with respect to 100 parts by weight of the monomer material,
A method for producing a water-repellent coating film, wherein a thin film of an SiO ₂ film having a CH ₃ group and / or a C ₂ H ₅ group remaining thereon is formed on a substrate by a CVD method.