JPH10249271A - Method for hydrophilization treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the hydrophilicity and stain resistance by carrying out electric discharge treatment or vacuum ultraviolet ray radiation treatment to the surface of a coating film of a synthetic resin in which silica fine particles are dispersed. SOLUTION: In a coating material field, the coating film surface of a coating for exterior use is required to be hydrophilic to have stain-proofness. In order to provide high hydrophilicity, discharge treatment or vacuum ultraviolet ray radiation treatment is carried out for the surface of a coating film of synthetic resin in which silica fine particles are dispersed. The hydrophilization treatment is preferably carried out for a coating film formed by applying a composition consisting of 100 pts.wt. of synthetic resin and 20-300 pts.wt. (based on silica wt.) of colloidal silica to the substrate surface and drying the resultant substrate. Any resin of thermosetting resin, thermoplastic resin, photo-curable resin may be used for the synthetic resin. The colloidal silica to be used is one produced by dispersing silica fine particles with 5-20nm average particle size in water or an organic solvent and as the organic solvent to disperse the silica in may be methanol, ethanol, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrophilizing treatment method having excellent hydrophilicity and stain resistance.

[0002]

2. Description of the Related Art In recent years, in the field of paints, attempts have been made to make the surface of the coating film hydrophilic in order to impart anti-staining properties to the coating film used outdoors. For example, JP-A-4-3701
No. 76 discloses a composition comprising a segmented polymer having a hydrophilic segment and a hydrophobic segment, and a coating resin. Also, Japanese Patent Laid-Open No. 7-331136
Japanese Patent Application Laid-Open Publication No. H11-157, discloses a resin composition for coatings to which a trifunctional or tetrafunctional alkyl silicate or a hydrolytic condensate thereof is added. However, according to the composition described in any of the above publications, the contact angle with water is 40 ° or more.
60 °, which is not particularly excellent as a hydrophilic property.

[0003] Japanese Patent Application Laid-Open No. Hei 7-136584 discloses that
After applying and curing a coating material in which an organosilicate and / or a hydrolyzed condensate thereof are mixed, an acid treatment is performed to develop hydrophilicity. However, even with this method, a high degree of hydrophilicity cannot be expected.

[0004] Further, colloidal silica is utilized in various paints and coating agents by taking advantage of its reactivity, hydrophilicity, high hardness and weather resistance. However, in the case of a coating film formed of a combination of colloidal silica and a general resin, a resin layer is present on the outermost surface, and in many cases, the hydrophilicity characteristic of colloidal silica does not appear.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems, and by combining silica fine particles with a general resin, has a very high hydrophilicity and a hydrophilicity excellent in stain resistance. It is an object to provide a processing method.

[0006]

The hydrophilization treatment method of the present invention is characterized in that the surface of a film in which fine silica particles are dispersed in a synthetic resin is subjected to a discharge treatment or a vacuum ultraviolet light irradiation treatment.

The above-mentioned film can be formed by applying and drying a composition comprising 20 to 300 parts by weight of colloidal silica based on 100 parts by weight of synthetic resin in terms of silica weight.

[0008] The synthetic resin used in the present invention is not particularly limited, and may be any of a thermosetting resin, a thermoplastic resin, and a photocurable resin. For example, various resins such as an acrylic resin, a polyester resin, a polyamide resin, a polyurethane resin, an epoxy resin, a vinyl resin, a silicone resin, an alkoxysilane-based resin, a photocurable acrylic resin, and a photocurable epoxy resin can be used. These may be used alone or in combination of two or more.

Colloidal silica has an average particle size of 5 to 200.
The silica fine particles of nm are dispersed in water or an organic solvent. This can be used even if the dispersion is stabilized in either the acidic region or the basic region,
Both can be used in combination.

As the organic solvent in which the silica is dispersed, methanol, ethanol, n-propanol, i-
Propanol, n-butanol, i-butanol, t-
Butanol, sec-butanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, tetrahydrofuran and the like. These can be used in combination of two or more.

The silica content of the coating composition in which the silica fine particles are dispersed in water or an organic solvent is 10 to 4%.
It is preferably in the range of 0% by weight.

Commercial products of colloidal silica dispersed in water include, for example, "Cataloid" series manufactured by Catalysis Chemical Co., Ltd. and "Snowtex" series manufactured by Nissan Chemical Co., Ltd. For example,
Examples include the "OSCAL" series manufactured by Catalysis Chemical Co., and the "organosilica sol" series manufactured by Nissan Chemical Co., Ltd.

In the present invention, 20 to 300 parts by weight of silica fine particles are blended with silica based on 100 parts by weight of the synthetic resin. If the amount of the silica fine particles is less than 20 parts by weight, the hydrophilicity after discharge treatment or after irradiation with vacuum ultraviolet light is poor, and the stain resistance becomes insufficient. On the other hand, if the amount is more than 300 parts by weight, there is a problem that the film cannot be formed uniformly, so that the compounding amount of silica is limited to the above range.

A composition in which silica is mixed with a synthetic resin can be diluted with an organic solvent. As the organic solvent used in this case, methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, sec-butanol, acetone,
Examples include methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, and tetrahydrofuran.

The composition used in the present invention may contain various additives such as a curing agent and a curing catalyst, a photoinitiator, an ultraviolet absorber, an antioxidant, a leveling agent and a thickening agent as long as their performance is not impaired. , A surfactant, an antibacterial / antifungal agent, and the like.

According to the method for hydrophilization treatment of the present invention, the above coating composition is applied to a substrate surface, dried, and then subjected to a discharge treatment to form a film having colloidal silica on the outermost surface. Therefore, a surface having excellent hydrophilicity and stain resistance can be obtained.

In order to apply the coating composition to the substrate surface, a dipping method, a spin coating method, a casting method, a curtain coating method, a roll coating method, or the like can be employed. The coating amount is preferably such that the film thickness after drying is 0.1 to 100 μm, and the drying condition is from room temperature to 20 μm.
It is several minutes to several hours in a range of about 0 ° C., and may be appropriately selected in consideration of the heat resistance of the base material. When a photocurable resin is used, it is cured by light irradiation to form a film. Light irradiation conditions are adjusted depending on the resin used.

The substrate is not limited at all,
Inorganic materials such as glass and metal, synthetic resins such as acrylic, polycarbonate, vinyl chloride and polyolefin, FRP
And the like. The surface of these substrates may be previously subjected to an adhesiveness improving treatment such as a corona discharge treatment, a plasma treatment, an ultraviolet irradiation, a chemical treatment, and a primer treatment.

According to the hydrophilic treatment method of the present invention, the above coating composition is applied to various substrates, dried and cured, and then subjected to discharge treatment or vacuum ultraviolet light irradiation, whereby hydrophilicity and stain resistance are reduced. An excellent film can be formed.

The hydrophilization treatment method of the present invention not only hydrophilizes the above-mentioned base material, but also uses a composition comprising the same synthetic resin and colloidal silica, for example,
A hydrophilic film and a hydrophilic sheet can also be obtained.

Examples of the discharge treatment include a corona discharge treatment and a plasma discharge treatment, and known devices and methods generally used for pretreatment of a substrate and the like can be employed. As the corona discharge treatment device, a general device including a high-frequency power supply, a discharge electrode, and a dielectric (for example, those manufactured by Kasuga Electric Co., Ltd., manufactured by Nippon Statec, etc.) can be used.

The processing conditions by corona discharge vary depending on the electrode structure, the distance between the electrodes, etc., but are usually 15 kV to 60 kV.
Processing may be performed by applying a voltage of the order of magnitude. If the applied voltage is too low, the time required for the treatment is prolonged, and if the applied voltage is too high, the arc discharge starts, so the above range is preferable.

In the case of the plasma discharge treatment, the method of generating plasma includes, for example, a method of applying a direct current, a microwave discharge, a method of decomposing a gas by plasma using electron cyclotron resonance, a method of thermally decomposing a gas by a hot filament, and the like. . Further, a method of performing the plasma treatment under a low pressure within a processing pressure of 1 × 10 ^{−4 to} 100 Torr is well known, but the plasma treatment may be performed under a pressure near the atmospheric pressure by a method described later.

When the plasma discharge treatment is performed under a low treatment pressure of 1 × 10 ^{-4 to} 100 Torr, the treatment pressure is appropriately selected depending on the excitation means and the treatment gas, but the apparatus is simple and the pressure is relatively high. It is preferably in the range of 1 × 10 ^{−2 to} 100 Torr in which glow discharge or plasma can be generated even in the state. When the processing pressure exceeds 100 Torr, the substrate becomes thermal plasma and shifts to arc discharge, so that the substrate is damaged. If it is less than 1 × 10 ⁻⁴ , expensive vacuum chambers and vacuum exhaust devices are required. Although the processing gas is not particularly limited, for example, argon, helium, nitrogen, oxygen, air and the like can be used.

In order to perform plasma discharge treatment under a low pressure, when the electrode structure is a parallel plate type, a coaxial cylindrical type, a curved flat plate type, a hyperboloid flat plate type, or the like, a DC voltage or an AC voltage is applied by a capacitive coupling method. Is done. Further, in the case of applying a high frequency, it is also possible to apply the induction type by using an external electrode. The input power required for the plasma discharge treatment under low pressure varies depending on the electrode area and shape, but is preferably 5 to 200 W (1 to 10 kV). If the input power is too low, processing takes time and is inefficient, and if it is too high, the substrate is damaged.

The distance between the electrodes is appropriately selected depending on the processing capacity, the thickness of the substrate, and the like. However, if the distance is too long, the plasma density decreases and high power is required. Should be as short as possible. The time for performing the plasma discharge treatment is appropriately selected depending on the treatment conditions and the composition of the treated surface, but a sufficient effect is exhibited in 1 to 30 seconds.

In the case where plasma discharge processing is performed at a pressure near the atmospheric pressure, the term "near the atmospheric pressure" means a pressure of 10 to 800 Torr, and the processing pressure is 700 to 780 Torr, which facilitates pressure adjustment and makes the apparatus simple. A range is preferred.

When the plasma discharge treatment is performed under a pressure near the atmospheric pressure, the shape of the electrode is not particularly limited. For example, a parallel plate type, a cylindrical opposed plate type, a spherical opposed plate type, a hyperboloid opposed plate type, a coaxial cylinder The solid derivative is disposed on at least one opposing surface of the opposing electrode. Examples of the solid derivative include synthetic resins such as polytetrafluoroethylene and polyethylene terephthalate, glass, silicon oxide, aluminum oxide, zirconium dioxide, metal oxides such as titanium dioxide, and double oxides such as barium titanate. .

The electric field applied between the electrodes may be a pulsed electric field other than the AC waveform itself, and it is preferable to apply a voltage so that the electric field intensity is about 1 to 100 kV / cm. If the input power is too low, processing takes time and is inefficient, and if it is too high, the substrate is damaged.

From the viewpoint of improving the degree of freedom in selecting a processing gas under atmospheric pressure and performing high-speed processing, it is preferable to apply a pulse electric field having a rise time and / or a fall time of 100 μs or less. Further, the frequency of the pulse electric field is preferably 1 to 100 KHz, and the ON time during one pulse is preferably continuous for 1 to 1000 μs.

Examples of the light source of the vacuum ultraviolet light used for the vacuum ultraviolet light irradiation performed in the present invention include an excimer laser, an excimer lamp, a low-pressure mercury lamp, a hydrogen discharge tube, a rare gas discharge tube and the like. Excimer lasers and excimer lamps that can obtain high-intensity vacuum ultraviolet rays are preferable, but excimer lamps are more preferable because of their large irradiation area.

The oscillation wavelength of an excimer laser or an excimer lamp varies depending on the type of medium gas.
193 nm for F laser, 157 n for F ₂ laser
m, 172 nm for Xe ₂ lamp, 1 for Kr ₂ lamp
With a 46 nm Ar ₂ lamp, light with a wavelength of 126 nm can be obtained.

Since the vacuum ultraviolet light is absorbed by air, it is desirable to irradiate it in an atmosphere of an inert gas such as a rare gas or nitrogen, or in a vacuum in order to increase the processing efficiency. The irradiation amount is appropriately determined depending on the processing conditions and the like. For example, when light of 10 W / cm ² is irradiated, a sufficient effect is exhibited if the processing time is 10 to 60 seconds.

According to the hydrophilization treatment method of the present invention, the coating film in which the silica fine particles are dispersed in the synthetic resin is subjected to discharge treatment or irradiation with vacuum ultraviolet light, so that the synthetic resin layer present on the outermost surface of the coating film is formed. The silica particles are destroyed and the silica fine particles are exposed. Therefore, a high degree of hydrophilicity is obtained, and dirt can be easily removed by washing with water or the like, and a surface layer having excellent stain resistance can be obtained.

When the discharge treatment is performed, it is considered that electrons, molecules, atoms, ions, and the like in the discharge space collide with the outermost surface resin layer, thereby breaking the resin bond. Vacuum ultraviolet light has a wavelength of 10
It is light of 0 to 200 nm, and the resin bond (C-C, C-
O) have sufficient photon energy to sever the photons. Therefore, it is considered that the bond of the outermost resin layer is broken.

[0036]

EXAMPLES Examples of the hydrophilic treatment method of the present invention will be described below. Example 1 γ-glycidoxypropyltrimethoxysilane (manufactured by Dow Corning Toray, trade name “SH604”)
0 ") 23 parts by weight of a 0.1N HCl aqueous solution were added to 100 parts by weight, and the mixture was stirred at room temperature for 1 hour to prepare a hydrolysis solution. This hydrolysis solution was added to colloidal silica (silica content 30% by weight, i-propanol dispersion;
274 parts by weight (trade name “OSCAL1432”) were mixed and uniformly mixed to obtain a coating composition.

The resulting composition was applied to the surface of a transparent polycarbonate plate (thickness: 3 mm, trade name “Lexan” manufactured by Asahi Glass Co., Ltd.) by a spin coating method so that the thickness after drying was 2 μm. After drying for a period of time, a film was formed. This film was very transparent and had high hardness. The contact angle of water on the film surface before corona discharge treatment was measured. 30 kV applied voltage and 0.4 k output to the above film
W, when the corona discharge treatment was performed at a treatment speed of 1 m / min, no change in appearance was observed.

Example 2 Poly (2-hydroxyethyl methacrylate) (manufactured by Aldrich, Mw = 30)
000) was uniformly dissolved in 900 parts by weight of ethyl cellosolve, and colloidal silica (silica content 30% by weight, i-propanol dispersion, manufactured by Catalysis Chemical Co., Ltd.)
333 parts by weight (trade name “OSCAL1432”) were mixed and uniformly mixed to obtain a coating composition.

The obtained composition was applied and dried on the same polycarbonate plate as used in Example 1 in the same manner as in Example 1 to form a film. In this state, the contact angle with water before the corona discharge treatment was measured. Further, the above-mentioned film was subjected to corona discharge treatment in the same manner as in Example 1.

Example 3 A film formed in the same manner as in Example 2 was processed using argon as a processing gas at a processing pressure of 1 Torr, a processing power of 25 W, a distance between electrodes of 2.5 cm,
Plasma discharge treatment (using a device manufactured by Samco International Laboratories) was performed with a treatment time of 10 seconds. The appearance of the film after the treatment was not changed.

Example 4 A propylene oxide-modified hydrogenated bisphenol A type epoxy resin (manufactured by Kyoei Chemical Co., Ltd.)
A coating composition was obtained by uniformly mixing 500 parts by weight of colloidal silica (silica content 30% by weight, i-propanol dispersion) with 100 parts by weight of trade name “Epolite 3002”.

The obtained composition was applied and dried on the same polycarbonate plate as used in Example 1 in the same manner as in Example 1 to form a film, and the contact angle with water before corona discharge treatment was measured. Corona discharge treatment was performed on the above-mentioned film in the same manner as in Example 1.

Example 5 Helium was used as a processing gas for the film formed in the same manner as in Example 4, a processing pressure of 760 Toor, a processing power of 100 W, an AC electric field distance of 2 mm, and TiO ₂ as a solid derivative. Then, a plasma discharge treatment was performed for a treatment time of 10 seconds. There was no change in the appearance of the film after the treatment.

(Example 6) 100 parts by weight of pentaerythritol triacrylate (trade name "PET-30", manufactured by Nippon Kayaku Co., Ltd.), which is a photocurable acrylic resin, was mixed with 1-hydroxycyclohexyl phenyl ketone (1-hydroxycyclohexylphenylketone) as a photoinitiator. Product name "Irgacure 18" manufactured by Nippon Ciba Geigy
4 ") 2 parts by weight, 2 parts by weight of ethyl 4-diethylaminobenzoate (trade name" Kayacure EPA ", manufactured by Nippon Kayaku Co., Ltd.) as a photoinitiator and colloidal silica (silica content 3)
333 parts by weight (0% by weight, i-propanol dispersion) were uniformly mixed to obtain a coating composition.

The composition obtained was the same as that used in Example 1.
Apply and dry on the same polycarbonate plate as in Example 1.
After forming a film by 500mJ /
cm ^TwoWas irradiated with ultraviolet rays. This film is very transparent
Good and high hardness. Before corona discharge treatment
After measuring the water contact angle, the film was treated in the same manner as in Example 1.
Corona discharge treatment was performed.

Example 7 A film formed in the same manner as in Example 6 was applied to a film having a center wavelength of 172 nm, a light amount of 10 W / cm ² ,
Irradiation time 30 seconds, vacuum ultraviolet light irradiation treatment under atmospheric pressure (Ushio Inc. excimer lamp, model "UER20-17")
2 "use). There was no change in the appearance of the film after the treatment.

(Example 8) Alicyclic epoxy resin (trade name "CELLOXIDE 2021P" manufactured by Daicel Chemical Industries, Ltd.) 10
0 parts by weight and colloidal silica (silica content 30% by weight,
i-propanol dispersion, manufactured by Catalyst Kasei Co., Ltd., trade name "OSC
AL1432 ") (500 parts by weight) to obtain a coating composition. The obtained composition was applied and dried on the same polycarbonate plate as that used in Example 1 in the same manner as in Example 1 to form a film.
m, a light amount of 10 W / cm ² , an irradiation time of 15 seconds, and a vacuum ultraviolet light irradiation treatment (using an excimer lamp manufactured by Ushio Inc., model “UER20-172”) in vacuum. There was no change in the appearance of the film after the treatment.

Example 9 A plasma processing apparatus equipped with a heat-resistant glass container (capacity: 5 liters) was used to attach an upper electrode (a stainless steel (SUS304) having a diameter of 80 mm) to a 1 mm diameter.
And a lower electrode (a stainless steel (SUS304) plate having a diameter of 80 mm) in a space with a distance of 6 mm between the lower electrode and a lower electrode (a stainless steel (SUS304) plate having a diameter of 80 mm). A partially stabilized thermal sprayed film of zirconium (thickness: 500 μm) was arranged, and the film surface formed in the same manner as in Example 1 was arranged with its upper surface facing upward.

The inside of the apparatus was evacuated by an oil rotary pump until the internal pressure of the apparatus became 1 Toor. Then, a desired amount of gas was introduced from a gas introduction pipe to bring the pressure in the apparatus to atmospheric pressure. A pulsed electric field having a peak value, a frequency, a pulse width, and a (rising / falling) time shown in Table 2 in an impulse waveform is applied between the electrodes.
For 2 seconds, discharge plasma was generated, and this was brought into contact with the base material to perform a plasma discharge process.

Example 10 A plasma discharge treatment was performed in the same manner as in Example 9 except that the film formed in the same manner as in Example 2 was used and the conditions of the impulse wave were as shown in Table 1.

Example 11 A plasma discharge treatment was performed in the same manner as in Example 9 except that the film formed in the same manner as in Example 4 was used and the conditions of the impulse wave were as shown in Table 1.

(Comparative Example 1) A polycarbonate plate to which the coating composition was not applied (contact angle to water: 86 °, contamination test ×) was subjected to corona discharge treatment under the same conditions as in Example 1, and then the contact angle to water was measured. It was measured.

(Comparative Example 2) A film formed in the same manner as in Example 8 was irradiated with a 3 kV high-pressure mercury lamp at an irradiation dose of 10 j / c.
Irradiated with ultraviolet light at m ² . The film was irradiated with ultraviolet rays using a conveyor-type ultraviolet irradiation device (high-pressure mercury lamp with a light source of 3 kV, manufactured by Eye Graphic, model “H03-L31”).

Evaluation of Performance The coatings obtained in Examples and Comparative Examples were evaluated for contact angle with water and contamination by the following methods. Table 2 shows the results. 1) Measurement of contact angle with water: Each was measured at three points using a contact angle meter (trade name “CA-X150”) manufactured by Kyowa Interface Science Co., Ltd., and expressed as an average value. 2) Stainability: A mixture of carbon black / liquid paraffin / ion-exchanged water = 9/1/40 was used as a stain substitute substance, which was applied to the surface of the film and dried at 70 ° C. for 5 minutes. And the state of removal of dirt was visually observed and evaluated in the following three stages. ；: No stain △: Slight stain ×: Stain is conspicuous

[0055]

[Table 1]

[0056]

[Table 2]

As is clear from Table 2, Examples 1 to 11
Are excellent in hydrophilicity and also excellent in stain resistance. However, those of Comparative Examples 1 and 2 are inferior in hydrophilicity and poor in stain resistance.

[0058]

The method for hydrophilization of the present invention has the above-mentioned structure, and the synthetic resin layer existing on the outermost surface of the film is destroyed, so that the exposed silica provides excellent hydrophilicity. Dirt can be easily removed,
A surface layer with excellent stain resistance is obtained.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Motokazu Yuasa 2-1 Hyakuyama, Shimamoto-cho, Mishima-gun, Osaka Sekisui Chemical Co., Ltd.

Claims (2)

[Claims] 1. A method for hydrophilizing, comprising subjecting a surface of a film formed by dispersing silica fine particles in a synthetic resin to a discharge treatment or a vacuum ultraviolet light irradiation treatment. 2. A film in which fine silica particles are dispersed in a synthetic resin is composed of a composition in which 20 to 300 parts by weight of colloidal silica is blended with respect to 100 parts by weight of the synthetic resin. The hydrophilic treatment method according to claim 1.