JP2003201437A - Resin coating with photocatalytic function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a normal temperature-curable halogen-containing resin coating composition giving coating film which has excellent heat resistance, weatherability, low-temperature film formability, coating film strength, contamination resistance and adhesiveness to substrate and also has the function of decompose toxic chemical substances including NOx, formaldehyde, acetaldehyde and ammonia by the aid of sunlight. <P>SOLUTION: The normal temperature-curable halogen-containing resin composition comprises a halogen-containing polymer dispersion, a crosslinking agent of formula (I): HS(CF<SB>2</SB>)nSH (wherein, n is an integer of 2-20) or formula (II) (wherein, R is a group selected from CF<SB>3</SB>, C<SB>2</SB>F<SB>5</SB>and C<SB>3</SB>F<SB>7</SB>), an aliphatic primary diamine compound as a crosslinking catalyst, a titanium oxide as a photocatalyst doped with chromium or vanadium, an iron oxide, and an alkaline substance such as MgO or CaO; wherein the halogen-containing resin is e.g. a vinylidene fluoride/chlorotrifluoroethylene/cyclohexyl vinyl ether copolymer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous dispersion prepared by copolymerizing chlorine-containing, bromine- or iodine-olefins, fluorine-containing olefins and olefinically unsaturated monomers,
Room temperature curing, characterized by containing a fluorine-containing dithiol compound as a crosslinking agent, an aliphatic primary diamine compound as a crosslinking catalyst, and a titanium oxide doped with a transition metal ion such as Cr or V by an ion implantation method as a photocatalyst. Water-based halogen-containing resin coating composition and aqueous coating composition containing the same.

[0002]

2. Description of the Related Art The principle of a photocatalyst that converts light energy into chemical energy was discovered by Professor Fujishima of the University of Tokyo. As the photocatalyst material, stannic oxide, zinc sulfide, potassium tantalate, zinc oxide, titanium oxide, strontium titanate, niobium oxide and the like are known, but titanium oxide is most often used. Titanium oxide has three crystal forms of anatase type, rutile type, and nitrite type, but it is generally said that the anatase type has the highest photoactivity. Conventionally, as a titanium oxide powder, Deg
Usa P-25 has been used for research on photocatalysts, but ST series (Ishihara Sangyo), PC series (Titanium industry), SSP series (Sakai Chemical) and the like are known in Japan. It was found that the photocatalytic reaction proceeded sufficiently even with the weak ultraviolet light existing in the living space, and the photocatalyst has come to be used for purification of the environment. The target is the extremely low concentration of harmful chemical substances such as ppm or ppb.

Studies have been conducted to fix a photocatalyst to a building material to have a deodorizing, antibacterial and antifouling function. Although the diffusion process is involved in deodorization, in the case of antibacterial and antifouling, the decomposition reaction is used for the substances existing on the solid surface, so when imparting antibacterial and antifouling functions to building materials, the photocatalytic reaction is There are advantages. Toto has developed antibacterial tiles and antibacterial sanitary ware by forming a thin film of titanium oxide on the surface of tiles and sanitary ware and applying a silver compound or copper compound. [Catalyst, 36 (7) 524 (1994). In addition to this, titanium oxide is applied to the surface of the cover glass for lighting in the tunnel (Toshiba Lightec), the fluororesin tent for outdoor installation (Nitto Denko), Japanese paper, etc. Those with a dirty function have been developed [Hyundai Kagaku, 8, 23 (199).
6)]

In recent years, active research has been carried out to remove toxic chemical substances and malodorous substances contained in the air by oxidative decomposition using a photocatalyst. Dr. Ibusuki oxidizes and decomposes nitrogen oxides in the air using a titanium oxide photocatalyst. [Ceramics, 31 (10) 829 (199
6)]. Since the adsorption power of NO ₂ to titanium oxide is small with titanium oxide alone, activated carbon is mixed as an adsorbent to oxidize NO ₂ to nitric acid. Surface area is 300m
^The amount of NOx removed and the amount of nitric acid recovered are significantly improved by using titanium oxide exceeding ² / g and adding an iron oxide having a good affinity for NOx and an alkaline substance used for wet absorption of NOx. . Fluororesin powder (0.3 μm) is used as a binder, and ultrafine particles of titanium oxide and activated carbon are mechanically mixed and molded into a sheet shape and fixed. It is also applied to decompose malodorous substances in the air,
Toyota Central Research Laboratories is conducting research on in-vehicle air purifiers that carry titanium oxide on honeycomb-structured activated carbon.
[Surface Chemistry, 16 (3) 206 (1995)]. Also,
Mitsubishi Chemical has developed titanium oxide composite activated carbon, which is a composite of activated carbon particles with titanium oxide of several tens of nm. [Europe
ean Carbon Conference “Ca
rbon96 "Newcastle UKJury, 2
97 (1996)].

However, conventional titanium oxide functions as a photocatalyst only under the irradiation of light in the ultraviolet region, and does not function under the irradiation of visible light that occupies most of indoor lights and sunlight. Therefore, there is a demand for a visible light-responsive titanium oxide photocatalyst that absorbs visible light and efficiently functions even when irradiated with visible light.

[0006]

The present invention is excellent in heat resistance, weather resistance, low-temperature film-forming property, coating film strength, stain resistance and substrate adhesion, and is suitable for NOx, formaldehyde, acetaldehyde, ammonia, mercaptan, etc. An object is to provide a halogen-containing copolymer aqueous dispersion composition having a function of irradiating a harmful chemical substance with visible light and photolyzing it, and an aqueous coating composition using the same.

The present inventor has found that an aqueous liquid prepared by copolymerizing a chlorine-containing, bromine- or iodine-olefin, a fluorine-containing olefin and an olefinically unsaturated monomer is subjected to ion implantation to obtain a transition metal such as Cr or V. Ion-doped titanium oxide, iron oxide and an alkaline substance are added, a fluorine-containing dithiol compound represented by the formula (I) or (II) is used as a crosslinking agent, and an aliphatic primary diamine compound is used as a crosslinking catalyst. The inventors have found that the above objects can be achieved by using them, and completed the present invention.

[0008]

According to the present invention, an olefinic unsaturated monomer copolymerizable with a chlorine-containing, bromine or iodine olefin and a fluorine-containing olefin is emulsion polymerized in an aqueous medium to obtain an average particle diameter of A dispersion of 0.05 to 3 μm is prepared, and a photocatalyst consisting of titanium oxide doped with Cr or V, an iron oxide and an alkaline substance is mixed by an ion implantation method, and a fluorine-containing dithiol compound is used as a crosslinking agent. An aqueous halogen-containing resin coating composition having a photocatalytic function, characterized in that an aliphatic primary diamine compound is used as.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the fluorinated olefin of the present invention include tetrafluoroethylene, trifluoroethylene, hexafluoropropylene, vinyl fluoride and vinylidene fluoride. Chlorine-containing olefins are chlorotrifluoroethylene, bromine-containing olefins are bromotrifluoroethylene, iodine-containing olefins are iodotrifluoroethylene, and olefinically unsaturated monomers are cyclohexyl acrylate, cyclohexyl methacrylate, cyclohexyl. Vinyl ether copolymer is preferred, vinylidene fluoride 55-75
Mol%, chlorotrifluoroethylene 5 to 25 mol% and cyclohexyl vinyl ether 10 to 20 mol%
A copolymer consisting of is preferred. As the titanium oxide photocatalyst, a mixed powder of titanium oxide, ferric oxide and magnesium oxide doped with Cr or V by an ion implantation method is desirable. The particle size of titanium oxide is preferably 5 to 20 nm, the particle size of ferric oxide is preferably 10 to 50 nm, and the particle size of magnesium oxide is preferably 10 to 50 nm.

When the content of vinylidene fluoride in the fluorine-containing copolymer is 55 mol% or more, a coating film having excellent mechanical properties such as pencil hardness of the film formed by drying the dispersion can be prepared. Further, when the content of chlorotrifluoroethylene, bromotrifluoroethylene or iodotrifluoroethylene is 5 mol% or less, the cross-linking density of the coating film is lowered and gloss and adhesion are deteriorated. When cyclohexyl vinyl ether is 10 mol% or more, the adhesion is improved. The average particle size of the fluorinated copolymer dispersion is 0.0
5 to 0.5 μm is preferable, and the solid content is preferably 40% by weight or more.

The aqueous fluorocopolymer dispersion can be usually produced by emulsion polymerization. For example, a fluoroolefin-containing monomer in which 0.01 to 1.0% by weight of a fluorine-based reactive emulsifying agent having a hydrophilic moiety and 0.1 to 1.0% by weight of a fluorine-based emulsifying agent coexist in water. It can be prepared by emulsion polymerization of the mixture. Further, in the coexistence of 1.0% by weight or less, preferably 0.2% by weight or less of a fluorosurfactant and 0.01 to 0.05% by weight of a nonionic non-fluorine surfactant with respect to water, It can also be prepared by emulsion-polymerizing a monomer mixture containing a fluoroolefin. The fluorinated copolymer dispersion prepared by these methods can stably contain particles having an average particle diameter of 0.2 μm or less at a high concentration of 30 to 50% by weight.

CH ₂ ═CFCF ₂ O [CF (CF ₃ ) CF is used as the fluorine-based reactive emulsifier having a hydrophilic moiety.
₂ O] nCF (CF ₃ ) COOH (n = 0 to 2)
Is used. The polymerization temperature is preferably 30 to 70 ° C, and 2
If the temperature is lower than 0 ° C, the stability of the produced latex is poor, and if it is higher than 120 ° C, the polymerization rate tends to be lowered due to chain transfer. Polymerization is usually 1.0 to 50 kg / cm _2.
It is carried out by heating under pressure for 5 to 100 hours. As the fluorine-based emulsifier, ammonium perfluorooctanoate, ammonium perfluorononanoate, etc. are used.

As the nonionic non-fluorine surfactant,
Polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether,
Examples thereof include polyoxyethylene octyl phenyl ether. Especially polyoxyethylene lauryl ether (E
O: 5 to 20, EO is the number of ethylene oxide units) is preferable.

Any polymerization initiator may be used as long as it can generate free radicals in an aqueous medium at a temperature of 20 to 90 ° C., and can be used in combination with a reducing agent. As the water-soluble polymerization initiator, persulfate, hydrogen peroxide, and as the reducing agent,
Sodium pyrobisulfite, sodium bisulfite, L-
Examples thereof include sodium ascorbate. The amount of the polymerization initiator used is 100 parts by weight of the total amount of the monomers,
The polymerization temperature is preferably 0.05 to 2.0 parts by weight, and the polymerization temperature is preferably 30 to 70 ° C.

As the solvent, it is possible to use a small amount of acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate or the like which does not adversely affect safety and environmental hygiene. In this way, the fluorocopolymer aqueous dispersion of the present invention can be prepared. However, from the viewpoint of improving the film-forming property and the adhesiveness, which are the objects of the present invention, any Tg (glass transition) of −35 to 25 ° C. An aqueous dispersion containing fluorinated copolymer particles having a temperature) can be prepared. The film forming temperature can be arbitrarily set in the range of 0 to 70 ° C. by selecting the Tg of the particles.

The average particle size of the particles of the aqueous dispersion of the present invention is preferably 0.1 to 0.2 μm. Average particle size is 0.05μ
If it is less than m, the clay of the aqueous dispersion increases, and a high-concentration aqueous dispersion cannot be obtained. On the other hand, if it exceeds 3 μm, the particles may settle and solidify during storage of the aqueous dispersion, so that the coating film may not have gloss.

As described above, the aqueous fluorocopolymer dispersion 10 is prepared by using a fluorodithiol compound containing two mercapto groups as a crosslinking agent in the aqueous fluorocopolymer dispersion 10.
It is desirable to add 1 to 15 parts by weight to 0 parts by weight. Further, it is desirable to add 0.1 to 10 parts by weight of an aliphatic primary diamine compound as a crosslinking catalyst. When the amount of the fluorine-containing dithiol compound is less than 1 part by weight, the crosslink density of the cast film becomes low, and when it exceeds 15 parts by weight, unreacted dithiol compound remains in the coating film and the gloss of the coating film decreases. There is. It is desirable to add 5 to 20 parts by weight of titanium oxide doped with Cr or V, 2 to 5 parts by weight of ferric oxide, and 2 to 10 parts by weight of magnesium oxide or calcium oxide by an ion implantation method.

Perfluorohexamethylenedithiol HS is particularly important among the fluorine-containing dithiol compounds.
(CF ₂ ) ₆ SH and bisthiophenol AF

Perfluorohexamethylenedithiol or bisthiophenol AF, which is one of the crosslinking agents of the present invention, can be synthesized, for example, according to the scheme shown in the following formula.

[0020]

[Chemical 3]

[Chemical 4]

The aliphatic primary diamine compound used as the crosslinking catalyst is preferably ethylenediamine, tetramethylenediamine, hexamethylenediamine or the like. To prepare paints with a very long pot life, use fluorocopolymer aqueous dispersions, dithiol compounds, titanium oxide photocatalysts, film-forming aids, dispersants, thickeners, defoamers and antifreeze agents. It is desirable to add an aliphatic primary diamine compound to the mixed solution immediately before use to obtain a coating material.

In the aqueous fluorocopolymer dispersion of the present invention, the fluorocopolymer is a vinylidene fluoride / chlorotrifluoroethylene / cyclohexyl vinyl ether copolymer, and the crosslinking agent is bisthiophenol AF or perylene. Fluorohexamethylenedithiol, and the aliphatic primary diamine is preferably ethylenediamine or hexamethylenediamine.

In the aqueous fluorocopolymer dispersion of the present invention,
Titanium oxide photocatalyst, film forming aid, pigment, thickener, dispersant,
Additives such as defoaming agents and antifreezing agents used in aqueous dispersion paints can be blended and used.
The aqueous fluorocopolymer dispersion composition of the present invention can be used as an aqueous coating composition for exteriors and interiors of buildings and structures. The water-based paint of the present invention can be applied using a roll coater, air spray, or the like. The water-based paint of the present invention can be used not only for metals but also for various base materials such as inorganic materials such as glass and cement, resins, wood, fibers and the like. The coating film can be dried and cured at room temperature for one day to one week after coating, depending on the type of crosslinking agent and crosslinking catalyst. The thickness of the coating film is preferably 20 to 50 μm.

The coated article thus prepared is very excellent in organic substance decomposing property, antibacterial property, NOx decomposing property, weather resistance, heat resistance, chemical resistance, adhesion and the like. It can be used for various purposes such as painting electric appliances, office equipment, automobiles, buildings and the like. The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0025]

EXAMPLES Example 1 Preparation of a halogen-containing copolymer dispersion: distilled water 5
00 ml, ammonium perfluorooctanoate.
5g and _{CH 2 = CFCF 2 OCF (CF} 3) CF 2
Reactive emulsifier represented by OCF (CF ₃ ) COOH 0.
5 g was charged into an autoclave with an internal volume of 1 L, nitrogen gas was pressure-injected and pressure deaeration was repeated, then dissolved air was removed, and vinylidene fluoride / chlorotrifluoroethylene /
A monomer mixture of 74/14/12 mol% of cyclohexyl vinyl ether was added at 10 kg / cm at a temperature of 60 ° C.
Pressurized to ² . Next, 1.5 g of ethyl acetate was pressed in, 0.2 g of ammonium persulfate was charged, and the pressure in the container was adjusted to 1
This mixed monomer was continuously supplied so as to be 0 kg / cm ^2, and the reaction was carried out for 50 hours. Then, the temperature was returned to room temperature and normal pressure to complete the reaction. When the solid content concentration of this aqueous dispersion was measured, it was 47% by weight. When the average particle size was measured with a laser light scattering particle size measuring device, it was 0.16μ.
It was m.

Preparation of Cr-doped Titanium Oxide: Chem.
Rev. 97, 2373 (1997). Corma
The method _{etc., Ti (O-i-Pr} ) 4, n-Pr 4
A titanium oxide sol was prepared by hydrothermal synthesis in an autoclave using NOH as a raw material, spin-coated on a glass substrate, and baked at 400 ° C. to form a titanium oxide thin film. Chromium was ionized in the ionization chamber using a 200 KeV ion implanter, doped with 1.3 μmol / g, and fired in air at a temperature of 450 ° C. The thin film was peeled from the glass substrate, coarsely pulverized with a cutter mill, and finely pulverized with a jet mill (Labjet, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to prepare chromium-doped titanium oxide particles having an average particle diameter of 10 nm.

Bisthiophenol AF1 was added to 100 parts by weight of the solid content of the aqueous dispersion prepared by the emulsion polymerization.
0 part, ethylenediamine 5 parts, chromium-doped titanium oxide (average particle size 10 nm) 30 parts, ferric oxide (manufactured by Tokyo Kasei) 10 parts, magnesium oxide (manufactured by Tokyo Kasei) 10
Parts, 2 parts of NOPCOSPERSE SN5027 (manufactured by San Nopco) as a dispersant, 1 part of ethylene glycol as an antifreezing agent, and FS Antifoam 013B0.5 as an antifoaming agent.
Parts, 0.5 parts of UH420 as a thickening agent, 10 parts of Dowanol DPnB (dipropylene glycol-n-butyl ether manufactured by Dow Chemical Co.) as a film forming aid, and 1 part of a fluorine-containing surfactant, 3000r with stirrer
The paint was prepared by mixing for 30 minutes at a speed of pm.

The above-prepared coating material was applied onto a float glass by using a roll coater so that the coating film had a thickness of 50 μm, and left standing at room temperature for 24 hours for curing.
The pencil hardness and adhesion of the coating film were measured according to JIS-K5400. Regarding the primary adhesion, a cellophane tape having a width of 24 mm was adhered to the test plate, and it was peeled off at a stretch to observe the surface condition. The second test for boiling water resistance is 2
The adhesion of the test plate soaked in time was similarly tested. The test results are shown in Table 1.

NOx oxidative decomposability: The above-prepared coating material was applied onto a glass plate of 120 × 140 mm by a roll coater so that the thickness of the coating film would be 50 μm, and left at room temperature for 24 hours. Cured. 2L of this glass plate
Put it in a container of 5 ppm and continuously pass 5 ppm of NOx gas,
After confirming that the concentration was stable, sunlight was irradiated.
The results are shown in FIG. 1, and it was confirmed that the NOx concentration was oxidatively decomposed to 1/100 or less by irradiation for 30 minutes. Aldehyde decomposition test: After the materials prepared in the NOx oxidative decomposition test were placed in a 3.5 L container and the acetaldehyde concentration in the container was adjusted to 200 ppm,
It was exposed to sunlight. The results are shown in FIG. 2. All of the acetaldehyde was decomposed by irradiating it with sunlight for 100 minutes. Ammonia decomposition test: The sample prepared in the NOx oxidative decomposition test was placed in a 3.5 L container, adjusted so that the ammonia concentration in the container was 50 ppm, and then irradiated with sunlight. The results are shown in FIG. 3. By irradiating with sunlight for 30 minutes, all of the ammonia was decomposed.

Comparative Example 1 As a photocatalyst, titanium oxide (ST-01, manufactured by Ishihara Sangyo Co., Ltd.,
A coating material was prepared in the same manner as in Example 1 except that 30 parts of an average particle diameter of 7 nm) was added, and a coating film characteristic test, NOx oxidative decomposition test, acetaldehyde decomposition test and ammonia decomposition test were performed. The results are shown in Table 1, FIG. 1, FIG. 2 and FIG.

Comparative Example 2 A coating material was prepared in the same manner as in Example 1 except that no titanium oxide photocatalyst was added, and a coating film characteristic test, NOx oxidative decomposition test, aldehyde decomposition test and ammonia decomposition test were conducted. The results are shown in Table 1, FIG. 1, FIG. 2 and FIG.

[0032]

[Table 1]

[0033]

EFFECTS OF THE INVENTION By using an aqueous coating composition containing the fluorine-containing copolymer aqueous dispersion of the present invention and a chromium or vanadium-doped titanium oxide photocatalyst, heat resistance, weather resistance, low temperature film-forming property, coating strength, resistance It is possible to prepare a coating film having excellent stain resistance and substrate adhesion and having a function of decomposing harmful chemical substances such as NOx, formaldehyde, acetaldehyde, and ammonia with sunlight, and can be used for a wide range of applications.

[Brief description of drawings]

1] Light irradiation time and N in NOx oxidative decomposition test
It is explanatory drawing which shows the relationship of the density | concentration of Ox.

FIG. 2 is an explanatory diagram showing a relationship between light irradiation and acetaldehyde concentration in an acetaldehyde decomposition test.

FIG. 3 is an explanatory diagram showing a relationship between a light irradiation time and an ammonia concentration in an ammonia decomposition test.

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[Procedure amendment]

[Submission date] March 15, 2002 (2002.3.1)
5)

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

Claims (4)

[Claims] 1. A halogen-containing polymer dispersion,
For example, vinylidene fluoride / chlorotrifluoroethylene / cyclohexyl vinyl ether copolymer, vinylidene fluoride / bromotrifluoroethylene / cyclohexyl vinyl ether copolymer, vinylidene fluoride / iodotrifluoroethylene / cyclohexyl vinyl ether copolymer, Formula [Chemical formula 1] (Wherein R is selected from the group consisting of CF ₃ , C ₂ F ₅ , and C ₃ F ₇ ), an aliphatic primary diamine compound as a crosslinking catalyst, and Cr by an ion implantation method. A room temperature curable aqueous halogen-containing resin coating composition comprising titanium oxide doped with transition metal ions such as V and V, iron oxide and an alkaline substance. The halogen-containing polymer is crosslinked and cured by the following reaction formula. [Chemical 2] 2. A water-based coating composition containing the composition according to claim 1. 3. A water-based paint for exterior and interior of buildings or structures, which contains the composition according to claim 1. 4. A coated article having a photocatalytic function coated with the water-based coating composition according to claim 2.