JP6539370B1 - Photocatalytic coating composition and coating method using the same - Google Patents

Abstract

A film to be formed has a good appearance with high transparency, exhibits sufficient photocatalytic activity even with a relatively small thickness, and imparts opposite properties of hydrophilicity and water resistance in a well-balanced manner. The present invention provides a photocatalytic coating composition that can A photocatalyst coating composition according to the present invention comprises a fluorine resin (A) containing at least a monomer unit represented by the following formula (I), a photocatalyst powder (B), and a solvent (C), Component (B) is contained at a ratio of 100 to 300 parts by mass with respect to 100 parts by mass of (A), and component (A) and component (B) are contained at a total concentration of 0.06 to 1% by mass. Be done. [Chem. 1] [C.] None

Description

  The present invention relates to a photocatalytic coating composition and a coating method using the same.

  For example, the outer wall of a building exposed to wind and rain, a tent fabric, or a paint used for painting a vehicle steel plate such as a car or a railway vehicle has a good appearance (excellent transparency) and is hard to adhere to dirt. Pollution resistance etc. are required. As such a paint, for example, a photocatalyst paint as described in Patent Document 1 is proposed.

  However, the photocatalytic paint has been hampered in widespread use in that it needs to go through a lot of steps in coating and is bothersome and a special spray coating machine is required. In the photocatalytic paint, a condensation type silicate inorganic compound is generally employed as a resin. Condensed silicate inorganic compounds have poor adhesion to organic substances and can not be thick-coated because their volume shrinkage is significant at the time of condensation. Furthermore, since the condensation type silicate inorganic compound inhibits the photocatalytic reaction, it is necessary to blend a large excess of the photocatalyst. As a result, since the reaction which corrodes the base of the organic type called "back reaction" arises, the priming process which prevents "back reaction" is needed.

  In order to eliminate such a phenomenon, using a fluorine resin as a resin is also examined. However, the content of the photocatalyst is too low to warn the decomposition of the resin in the photocatalytic reaction, so that sufficient photocatalytic function and hydrophilicity can not be exhibited. In order to exert these effects, it is necessary to apply a large amount of a photocatalytic paint to thicken the layer, which requires further complicated steps.

JP 2013-124312 A

  The object of the present invention is that the film to be formed has a good appearance with high transparency, exhibits sufficient photocatalytic activity even with a relatively small thickness, and imparts well-balanced opposite properties of hydrophilicity and water resistance. It is an object of the present invention to provide a photocatalytic coating composition that can be used and a coating method using this composition.

（２）成分（Ａ）が、下記式（ＩＩ）に示されるモノマー単位をさらに含む樹脂である上記（１）に記載の光触媒塗料組成物。

式（ＩＩ）中、Ｃ_mＦ_2mおよびＣ_nＦ_2nは直鎖または分岐のパーフルオロアルキレン基であり、ｍは１〜１０の整数であり、ｎは１〜５の整数である。
（３）式（ＩＩ）に示されるモノマー単位が、パーフルオロ［２−（フルオロスルホニルエトキシ）プロピルビニルエーテル］に由来するモノマー単位である上記（２）に記載の光触媒塗料組成物。
（４）成分（Ａ）が、８００以上のスルホン酸当量を有する上記（２）または（３）に記載の光触媒塗料組成物。
（５）成分（Ｂ）が、酸化チタン、酸化タングステン、酸化亜鉛および酸化鉄からなる群より選択される少なくとも１種である（１）〜（４）のいずれかに記載の光触媒塗料組成物。
（６）上記（１）〜（５）のいずれかに記載の光触媒塗料組成物を、ローラー塗装によって基材に塗布する塗装方法。 As a result of intensive studies to solve the above problems, the present inventor has found a solution having the following configuration, and has completed the present invention.
(1) The component (A) contains at least a monomer unit represented by the following formula (I), a photocatalyst powder (B), and a solvent (C), and the component is based on 100 parts by mass of the component (A) The photocatalyst coating composition containing (B) in a ratio of 100 to 300 parts by mass and containing the component (A) and the component (B) in a total concentration of 0.06 to 1% by mass.

(2) The photocatalyst paint composition according to the above (1), wherein the component (A) is a resin further containing a monomer unit represented by the following formula (II).

In the formula (II), C _m F _{2 m} and C _n F _{2 n} are linear or branched perfluoroalkylene groups, m is an integer of 1 to 10, and n is an integer of 1 to 5.
(3) The photocatalyst paint composition according to the above (2), wherein the monomer unit represented by the formula (II) is a monomer unit derived from perfluoro [2- (fluorosulfonylethoxy) propyl vinyl ether].
(4) The photocatalyst paint composition according to the above (2) or (3), wherein the component (A) has a sulfonic acid equivalent of 800 or more.
(5) The photocatalyst paint composition according to any one of (1) to (4), wherein the component (B) is at least one selected from the group consisting of titanium oxide, tungsten oxide, zinc oxide and iron oxide.
(6) The coating method which apply | coats the photocatalyst coating composition in any one of said (1)-(5) to a base material by roller coating.

  According to the photocatalytic coating composition of the present invention, the formed film has a good appearance with high transparency, and exhibits sufficient photocatalytic activity even if the thickness is relatively thin. Furthermore, the formed film has well-balanced contradictory properties of hydrophilicity and water resistance. Furthermore, according to the coating method of the present invention, the photocatalytic coating composition can be applied to the substrate in simple steps without complicated steps, and a film having a relatively thin thickness is formed on the substrate. Can.

  The photocatalyst coating composition of the present invention comprises a fluororesin (component (A)) containing at least a monomer unit represented by the above formula (I), a photocatalyst powder (component (B)), and a solvent (component (C)). including. Hereinafter, these components will be described in detail.

  The component (A) contained in the photocatalyst paint composition according to one embodiment of the present invention is not particularly limited as long as it is a fluorine resin containing at least a monomer unit represented by the following formula (I).

  As such a fluorine resin, for example, polytetrafluoroethylene, a copolymer of tetrafluoroethylene and a monomer copolymerizable with tetrafluoroethylene, a perfluoroalkyl graft polymer of polytetrafluoroethylene and the like can be mentioned. As a monomer copolymerizable with tetrafluoroethylene, a fluorine-containing monomer is mentioned, for example. Among the fluorine-containing monomers, the most fluorinated monomer, that is, a monomer in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms is preferable. By using a fluorine resin having no carbon-hydrogen bond (C-H bond) in the main chain and side chain as the component (A), the durability to the photocatalyst is further improved, and a more excellent photocatalytic activity is exhibited. be able to.

  As the fluorine-containing monomer, perfluoro [2- (fluorosulfonylalkoxy) alkyl vinyl ether represented by the following formula (III) is particularly preferable.

In formula (III), C _m F _{2 m} and C _n F _{2 n} are linear or branched perfluoroalkylene groups, m is an integer of 1 to 10, and n is an integer of 1 to 5.

A monomer unit derived from perfluoro [2- (fluorosulfonylalkoxy) alkyl vinyl ether represented by the formula (III) is a monomer unit represented by the above formula (II). Among the perfluoro [2- (fluorosulfonylalkoxy) alkyl vinyl ethers represented by the formula (III), a perfluorocarbon wherein C _m F _{2 m} has a branched structure, m is 3 and _n in C _n F ₂ n is 2 [2- (fluorosulfonylethoxy) propyl vinyl ether (in the monomer unit represented by the formula (II), C _m F _{2 m} has a branched structure and m is 3 and _n of C _n F ₂ n is preferably 2) . The copolymer of tetrafluoroethylene and perfluoro [2- (fluorosulfonylethoxy) propyl vinyl ether is commercially available, for example, "Nafion (Nafion)" (manufactured by Chemours).

  The molecular weight of the component (A) is not particularly limited and preferably has a weight average molecular weight of 10,000 to 2,000,000, and more preferably a weight average molecular weight of 20,000 to 1,000,000. In particular, in the case of a copolymer in which component (A) contains a monomer unit represented by formula (I) and a monomer unit represented by formula (II), sulfonic acid is substituted for the specific molecular weight (weight average molecular weight). The equivalent weight may be measured and used as a measure of molecular weight (weight average molecular weight). The sulfonic acid equivalent is the molecular weight of the polymer per sulfonic acid group. A copolymer (specific copolymer) containing the monomer unit represented by the formula (I) and the monomer unit represented by the formula (II) preferably has a sulfonic acid equivalent of 800 or more, more preferably 900 or more Have sulfonic acid equivalents of By using specific copolymers having a sulfonic acid equivalent of 800 or more, better water resistance can be imparted. In the specific copolymer, the upper limit of the sulfonic acid equivalent is not limited. The upper limit of the sulfonic acid equivalent is preferably about 1300, taking into consideration the water solubility of the specific copolymer or the solubility essential for forming a coating solution in another solvent.

The component (B) contained in the photocatalyst paint composition according to one embodiment is not particularly limited as long as it is a compound having photocatalytic activity. A photocatalyst is a catalyst (compound) which produces an oxidizing power by irradiation with sunlight, fluorescent light, etc. and exhibits a purification effect, a deodorizing effect, an antifouling effect, a water purification effect, an antibacterial effect and the like. Examples of the component (B) include titanium oxide, tungsten oxide, zinc oxide, iron oxide, and zirconium oxide. _{Specifically, TiO 2, WO 3, ZnO} , Fe 2 O 3, Fe 3 O 4, ZrO ₂ or the like can be mentioned. As component (B), for example, ST-01 (manufactured by Ishihara Sangyo Co., Ltd.), Selmuse (manufactured by Daicel Co., Ltd., titanium oxide photocatalyst), etc. are commercially available.

  If a component (B) is a powder, an average particle diameter etc. will not be specifically limited. In consideration of the transparency of the film to be formed, the particle diameter of the powder is preferably smaller. For example, a powder having a secondary particle diameter of about 0.4 to 2.0 μm is preferable. The average particle size is measured, for example, by a particle size distribution analyzer.

  The component (B) is contained in the ratio of 100-300 mass parts with respect to 100 mass parts of components (A) in the photocatalyst coating composition which concerns on one Embodiment. When the content of the component (B) is less than 100 parts by mass, sufficient hydrophilicity is not imparted to the formed film. Furthermore, the proportion of the component (A) increases, and the proportion of the component (B) decreases, so that sufficient photocatalytic activity can not be exhibited. On the other hand, when the content of the component (B) exceeds 300 parts by mass, the transparency of the formed film is impaired, and a chalking phenomenon in which the component (B) floats on the surface of the formed film also occurs. Component (B) is preferably contained in a proportion of 150 to 250 parts by mass with respect to 100 parts by mass of component (A).

  The component (C) contained in the photocatalyst paint composition according to one embodiment is not particularly limited as long as it is a solvent capable of dissolving the component (A) and dispersing the component (B). Such solvents include water, alcohols having 1 to 4 carbon atoms, ketones such as acetone and methyl ethyl ketone (MEK), ethers such as diethyl ether and dioxane, acetates such as methyl acetate and ethyl acetate, etc. Can be mentioned. Among these, water, ethanol or hydrous ethanol is preferable in consideration of workability and load on the environment.

  In the photocatalyst paint composition according to one embodiment, the component (C) is included such that the component (A) and the component (B) have a total concentration of 0.06 to 1% by mass (nonvolatile content). If component (C) is used so that component (A) and component (B) total less than 0.06% by mass, the concentration of non-volatile components is too low, and it becomes difficult to form a film. On the other hand, when the component (C) is used so that the component (A) and the component (B) in total exceed 1% by mass, the concentration of the non-volatile component becomes too high and the coating amount increases. As a result, the amount of the component (B) contained in the film to be formed is increased, and the coating film becomes cloudy, which is not preferable in appearance. Furthermore, the cost is also high. The component (C) is contained such that the component (A) and the component (B) together have a concentration of preferably 0.1 to 0.5% by mass.

  The method for producing the photocatalytic coating composition according to one embodiment is not particularly limited, and is the same as a known conventional paint production process. That is, first, the component (A) and the component (B) may be well dispersed in a disperser, and then the component (C) may be mixed and stirred. In addition to the component (A), the component (B) and the component (C), additives generally contained in the paint composition may be mixed as needed within the range that does not inhibit the effects of the present invention. Examples of such additives include preservatives, fungicides, ultraviolet absorbers, antioxidants, antifoaming agents, leveling agents, dispersing agents, plasticizers, antisettling agents, anti-sagging agents, and the like.

  The photocatalytic coating composition thus obtained is applied to a substrate. The base material is not particularly limited, and examples thereof include buildings, apartments, houses, bridges, levees, dams, structures including buildings such as gates and gates, tent fabrics, car body steel plates such as cars and railway cars, objects, Monuments etc. can be mentioned. The photocatalytic coating composition according to one embodiment is applied to the wall surface (surface) and the roof of such a substrate, in particular, to the wall surface, the roof, and the water around a bathroom exposed to wind and humidity.

  The photocatalyst paint composition according to one embodiment may not be applied thick, unlike a conventional photocatalyst paint containing a fluorocarbon resin. In the photocatalytic coating composition according to one embodiment, the coating formed even by relatively thin application exhibits sufficient photocatalytic activity, has a good appearance with high transparency, It does not affect the design etc. Furthermore, in the photocatalyst coating composition according to one embodiment, the photocatalyst powder (component (B)) is contained at a relatively high ratio to the ratio of the fluorine resin (component (A)). Thus, by blending the photocatalyst powder in a relatively high ratio, the film to be formed exerts not only water resistance derived from the fluorocarbon resin but also hydrophilicity, that is, opposite properties of hydrophilicity and water resistance. I found that it works well.

  The method for applying the photocatalytic coating composition according to one embodiment is not particularly limited, but the photocatalytic coating composition according to one embodiment is most characterized in that it can be roller-coated. That is, since the photocatalyst paint composition according to one embodiment may not be applied thick, it can be applied to a substrate by roller coating. The application specification of the conventional photocatalyst coating agent needed to prepare a large-scaled apparatus and was limited to the spray coating which needed training. The photocatalyst coating composition according to one embodiment can adopt roller coating as a construction specification. As a result, it becomes possible to construct more easily, and the construction cost can be dramatically reduced. A relatively thin coating can be conveniently formed on a substrate by applying the photocatalytic coating composition according to one embodiment only once or twice with a roller. The film thus formed has a thickness of, for example, about 0.1 to 2.0 μm, preferably about 0.1 to 0.9 μm.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited to these examples.

Example 1
The photocatalytic paint was prepared by mixing the component (A), the component (B) and the component (C) shown below. Specifically, 10 parts by mass of Nafion DE 521 (0.5 parts by mass in terms of component (A)) and 5 parts by mass of cell muse (0.5 parts by mass in terms of component (B)) are mixed The mixture was sufficiently dispersed by a paint disperser. Next, 45 parts by mass of ethanol and 40 parts by mass of water were added and thoroughly mixed to obtain a photocatalytic paint. The obtained photocatalyst paint contains 100 parts by mass of component (B) with respect to 100 parts by mass of component (A), and the concentration of component (A) and component (B) is 1% by mass in total. (Nonvolatile content: 1% by mass) is included.
Component (A): Nafion DE 521 (manufactured by Chemours, sulfonic acid equivalent: 1000, 5% by mass dispersion)
Component (B): Cellmuse (manufactured by Daicel Corporation, titanium oxide photocatalyst, 10% by mass dispersion)
Component (C): ethanol and water

(Example 2)
0.6 parts by mass of Nafion DE 521 (0.03 parts by mass converted to component (A)), 0.3 parts by mass of selmuse (0.03 parts by mass converted to component (B)), 50 parts by mass The photocatalytic paint was obtained in the same manner as in Example 1 except that ethanol and 49.1 parts by mass of water were used. Component (B) is contained in the proportion of 100 parts by mass with respect to 100 parts by mass of component (A) in the obtained photocatalyst paint, and the total of 0.06 mass% of components (A) and (B) (Non-volatile content: 0.06% by mass).

(Example 3)
0.6 parts by mass of Nafion DE 521 (0.03 parts by mass converted to component (A)), 0.6 parts by mass of selmuse (0.06 parts by mass converted to component (B)), 50 parts by mass The photocatalytic paint was obtained in the same manner as in Example 1 except that ethanol and 48.8 parts by mass of water were used. The obtained photocatalyst paint contains 200 parts by mass of component (B) with respect to 100 parts by mass of component (A), and the total of 0.09% by mass of components (A) and (B) (Non-volatile content: 0.09 mass%).

(Example 4)
0.4 parts by mass of Nafion DE 521 (0.02 parts by mass converted to component (A)), 0.6 parts by mass of selmuse (0.06 parts by mass converted to component (B)), 50 parts by mass The photocatalytic paint was obtained in the same manner as in Example 1 except that ethanol and 49.0 parts by mass of water were used. The obtained photocatalyst paint contains 300 parts by mass of component (B) with respect to 100 parts by mass of component (A), and the total of 0.08 mass% of components (A) and (B) (Non-volatile content: 0.08% by mass).

(Comparative example 1)
13.2 parts by mass of Nafion DE 521 (0.66 parts by mass converted to component (A)), 3.4 parts by mass of selmuse (0.34 parts by mass converted to component (B)), 50 parts by mass The photocatalytic paint was obtained in the same manner as in Example 1 except that ethanol and 33.4 parts by mass of water were used. The obtained photocatalyst paint contains about 50 parts by mass of the component (B) per 100 parts by mass of the component (A), and the component (A) and the component (B) are 1% by mass in total. It is included at a concentration (nonvolatile content: 1% by mass).

(Comparative example 2)
4 parts by mass of Nafion DE 521 (0.2 parts by mass in terms of component (A)), 8 parts by mass of cell muse (0.8 parts by mass in terms of component (B)), 50 parts by mass of ethanol and 38 A photocatalytic paint was obtained in the same manner as in Example 1 except that mass parts of water were used. The obtained photocatalyst paint contains 400 parts by mass of component (B) per 100 parts by mass of component (A), and the concentration of component (A) and component (B) is 1% by mass in total. (Nonvolatile content: 1% by mass) is included.

(Comparative example 3)
Instead of Nafion DE 521 used in Example 1, a silicate oligomer (MKC Silicate MS56, manufactured by Mitsubishi Chemical Corporation) was used. First, 9.5 parts by mass of ethanol was added to 0.5 parts by mass of MKC silicate MS56 to prepare a solution having a concentration of silicate oligomer of 5% by mass. The same solution as in Example 1 except that the obtained solution (10 parts by mass), 5 parts by mass of cellmuse (0.5 parts by mass in terms of component (B)), and 85 parts by mass of ethanol were used A photocatalytic paint was obtained by the procedure.

  Each of the photocatalyst paints obtained in each example and each comparative example was applied to a substrate and subjected to a photocatalytic performance test. The specific test method is as follows. First, an aqueous white paint (water-based fine coat silicon, manufactured by Kikusui Chemical Industries, Ltd.) was applied to an aluminum base so that the dry film had a thickness of 80 μm. The aqueous white paint was thoroughly dried to obtain a substrate.

  Each photocatalyst paint was apply | coated once with the short hair roller (hairy foot: 4 mm) on the coated surface of the obtained base material. When the photocatalyst paint obtained in Comparative Example 3 was applied, 100 ppm of dibutyltin diacetate was added as a curing catalyst for a silicate oligomer. Then, the substrate coated with the photocatalytic paint was sufficiently dried (over 168 hours) under an environment of temperature 25 ° C. and relative humidity 60% to obtain a test plate. The photocatalytic films formed on the test plate each had a thickness of about 0.2 μm (estimated by the calculated value). The results of visual observation of the appearance of the obtained test plates are shown in Tables 1 and 2. Furthermore, based on JISR1703-1, limit contact angle measurement was performed about each obtained test board. The limit contact angle measurement was performed after visually observing the appearance and after the test plate was immersed in tap water for 168 hours and dried. It can be evaluated that the smaller the contact angle, the better the water resistance. The results are shown in Tables 1 and 2.

  As shown in Table 1, the test plates coated with the photocatalytic paint obtained in Examples 1 and 2 did not generate phenomena such as the chalking phenomenon that affect the appearance, and had an excellent appearance. I understand that Although the test plates coated with the photocatalytic paint obtained in Examples 3 and 4 are slightly milky white, they are not colored to impair the transparency and there is no problem in practicality at all. It can be seen that the test plates coated with the photocatalytic paint obtained in Examples 1 to 4 have small critical contact angles and have excellent hydrophilicity. Furthermore, the test plate which apply | coated the photocatalyst coating material obtained in Examples 1-4 does not have a difference in the limit contact angle before being immersed in a tap water, and the limit contact angle after being immersed. From this result, it is clear that when the obtained test plate is immersed in tap water, the formed photocatalytic film is not washed away, and the test plate coated with the photocatalytic paint obtained in Examples 1 to 4 Are found to have excellent water resistance.

  On the other hand, as shown in Table 2, it can be seen that the test plate coated with the photocatalyst paint obtained in Comparative Examples 1 to 3 has a chalking phenomenon or poor water resistance. As shown in Comparative Example 1, when the proportion of the fluorine resin is high, although the appearance of the test plate is excellent, it is understood that the hydrophilicity is poor. As shown in Comparative Example 2, when the ratio of the photocatalyst is high, it can be seen that the chalking phenomenon occurs in the test plate. Furthermore, in the obtained test plate, the difference between the limit contact angle before immersion in tap water and the limit contact angle after immersion is large, and the formed film is washed away by immersion in tap water, that is, water resistance It is clear that As shown in Comparative Example 3, when a silicate oligomer generally used as a resin is used, when it is coated using a roller, it can be seen that a chalking phenomenon occurs in the test plate.

Claims (6)

A fluorine resin (A) containing at least a monomer unit represented by the following formula (I), a photocatalyst powder (B), and a solvent (C),
The average particle size of the component (B) is 0.4 to 2.0 μm as a secondary particle size,
Component (B) is contained in a ratio of 100 to 300 parts by mass with respect to 100 parts by mass of component (A),
Component (A) and component (B) are contained in a total concentration of 0.06 to 1% by mass,
Photocatalytic paint composition.

The photocatalytic paint composition according to claim 1, wherein the component (A) is a resin further containing a monomer unit represented by the following formula (II).

In the formula (II), C _m F _{2 m} and C _n F _{2 n} are linear or branched perfluoroalkylene groups, m is an integer of 1 to 10, and n is an integer of 1 to 5.   The photocatalytic coating composition according to claim 2, wherein the monomer unit represented by the formula (II) is a monomer unit derived from perfluoro [2- (fluorosulfonylethoxy) propyl vinyl ether].   The photocatalytic paint composition according to claim 2 or 3, wherein the component (A) has a sulfonic acid equivalent of 800 or more.   The photocatalytic coating composition according to any one of claims 1 to 4, wherein the component (B) is at least one selected from the group consisting of titanium oxide, tungsten oxide, zinc oxide and iron oxide.   The coating method which apply | coats the photocatalyst coating composition in any one of Claims 1-5 to a base material by roller coating.