JP2006241408A - Coating liquid formulated with organic coloring matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating liquid formulated with an organic coloring matter, enabling the presence or absence of coating to be easily ascertained by visual observation, and thereafter promptly and uniformly decolored even in a case of not being irradiated with ultraviolet rays or in a case of being irradiated with the ultraviolet rays with weak irradiation intensity. <P>SOLUTION: The coating liquid formulated with the organic coloring matter contains the organic coloring matter oxidatively decomposed by active oxygen, and a compound generating the active oxygen. The color is stably and precisely decolored by the active oxygen generated from the compound generating the active oxygen in the liquid even in the case of not being irradiated with the ultraviolet rays or in the case of being irradiated with the ultraviolet rays with the weak irradiation intensity because the organic coloring matter contained in the coating liquid formulated with the organic coloring matter is oxidatively decomposed by the active oxygen. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic dye-containing coating liquid, and in particular, the presence or absence of film formation with a photocatalyst coating liquid or the like can be easily confirmed visually by coloring the organic dye, and thereafter the organic dye is reliably decomposed. The present invention relates to an organic dye-containing coating solution that can be decolored.

  A photocatalyst generates electron and hole pairs when irradiated with ultraviolet rays, generates radical substances of hydroxy radicals and superoxide anions, and decomposes environmental pollutants and odorous substances, thereby preventing antifouling, deodorizing, antibacterial, etc. Demonstrates various functions. In addition, when the photocatalyst is photoexcited by irradiation with ultraviolet rays, the surface of the photocatalyst film is highly hydrophilized so that the contact angle with water becomes about 0 degree. The surface of the photocatalyst film thus made highly hydrophilic can be prevented from being fogged by condensed moisture or steam, or being swollen by attached water droplets. In addition, the adhering hydrophobic dust and contaminants are washed away with rain water and the like, and the surface is purified, thereby obtaining a good self-cleaning function.

  Such photocatalysts include metal oxides such as titanium oxide, tin oxide, tungsten oxide, and zinc oxide, and metal sulfides such as cadmium sulfide and copper sulfide. Among them, titanium oxide, particularly anatase type titanium oxide, It is known that the photocatalytic activity is excellent. The photocatalyst film is formed by applying a coating liquid prepared by dissolving or dispersing these photocatalyst fine powders in water or an organic solvent to a substrate to be treated, and drying and curing as necessary.

  The photocatalyst film formed in this manner is the one that exhibits photocatalytic activity only when it is irradiated with a sufficient amount of ultraviolet light to exhibit photocatalytic activity. Because it is colorless and transparent in order not to change the property, there is almost no difference in appearance between the coated part of the photocatalyst coating liquid and the uncoated part, that is, the surface where the photocatalyst film is formed and the surface where the photocatalyst film is not formed Absent. For this reason, the presence or absence of the photocatalyst film cannot be easily confirmed visually. In addition, this causes generation of defective products due to unpainted film in the photocatalyst film forming process, and makes the process operation and management complicated, such as overcoating for preventing unpainted film.

  Such a problem is not limited to the photocatalytic film, but is common to colorless and transparent or translucent coating solutions. For example, when a photocatalytic film is formed on an organic base material, a base layer is usually formed to protect the base material from the oxidative decomposition reaction of the photocatalyst. Like the film coating solution, it was colorless and transparent, so it was not possible to easily confirm the presence or absence of the coating visually.

Conventionally, in order to solve such problems, in the photocatalyst coating liquid, a colorant that is oxidatively decomposed and decolored by a photocatalyst such as an azo dye, a phthalocyanine dye, or a metal-containing organic dye such as an organometallic complex is used. There has already been proposed a method in which the visibility of the coated part is improved by addition and the colorant is decolored by the oxidative decomposition action of the photocatalyst so as not to change the design of the substrate (International Publication WO00 / 33977).
International Publication WO00 / 33977

  However, in the coating liquid described in International Publication WO 00/33977, the colorant is decolored by oxidative decomposition by a photocatalyst, and therefore the decoloring speed greatly depends on the ultraviolet intensity. When applied to a building or the like, there is a large variation in the decoloring speed due to the weather (fine weather or cloudy weather) after application, and there is a problem that the colorant in the shaded part is not easily decolored.

  In addition, a binder coating solution for a base layer that does not contain a photocatalyst cannot be applied to a coating solution that does not contain a photocatalyst, such as a binder coating solution for a base layer, because such a photocatalytic decoloring effect cannot be obtained. It was.

  The present invention solves the above-mentioned conventional problems, and can be easily confirmed visually by the presence or absence of coloration, and even after that, even when ultraviolet rays are not irradiated or when the ultraviolet irradiation intensity is weak An object of the present invention is to provide an organic dye-containing coating liquid that can be uniformly decolorized at an early stage.

  The organic dye-containing coating liquid of the present invention includes an organic dye that is oxidatively decomposed by active oxygen and a compound that generates active oxygen.

  Since the organic dye contained in the organic dye-containing coating liquid of the present invention is oxidatively decomposed by active oxygen, the active oxygen generated from the compound that generates active oxygen in the liquid is not irradiated with ultraviolet light or is irradiated with ultraviolet light. Even when the strength is weak, the color is stably and reliably erased.

  In the present invention, the organic pigment that is oxidatively decomposed by active oxygen includes one or more selected from the group consisting of a cationic methine dye, a triphenylmethane dye, and a triallylmethane dye, The amount is preferably 0.001 to 0.1% by weight.

  In addition, examples of the compound that generates active oxygen include one or more selected from the group consisting of hydrogen peroxide, peroxotitanic acid, chlorate, hypochlorite, and permanganate. Note that peroxotitanic acid functions as both a binder (substrate protective agent) and a substance that generates active oxygen.

  The organic dye-containing coating liquid of the present invention is useful as a photocatalytic coating liquid for forming a photocatalytic film. The organic dye-containing coating solution of the present invention is also useful as a binder coating solution for forming an underlayer of a photocatalytic film.

  With the organic dye-containing coating liquid of the present invention, the presence or absence of application can be easily visually confirmed by the presence or absence of coloring of the mixed organic dye, and after that, the ultraviolet irradiation intensity is weak or the ultraviolet irradiation intensity is weak Even in such a case, the color can be quickly and uniformly erased by oxidative decomposition of the organic dye with active oxygen generated from the compound that generates active oxygen. For this reason, the problem of the color residue resulting from the dispersion | variation in the decoloring speed by the weather or the degree of sunshine of an application part can be solved. Further, the present invention is not limited to the photocatalyst coating solution, and can be effectively applied to various colorless and transparent or semi-transparent coating solutions used for all parts.

  Hereinafter, embodiments of the organic dye-containing coating solution of the present invention will be described in detail.

  The organic dye-containing coating solution of the present invention contains an organic dye that is oxidatively decomposed by active oxygen and a compound that generates active oxygen. Among these, as an organic dye that is oxidatively decomposed by active oxygen, Hodogaya Chemical Industries Cationic methine dyes such as Aizen Astra Phloxine FF conc. Manufactured by Co., Ltd. Triphenylmethane dyes such as Aizen Diamond Green GH manufactured by Hodogaya Chemical Industry Co., Ltd. Examples include triallylmethane dyes. These dyes may be used alone or in combination of two or more.

  If the content of these organic dyes is too small, coloring by the organic dyes cannot be obtained sufficiently, and if it is too much, there is no difference in visibility, and the use amount of the organic dyes and compounds that generate active oxygen increases. In addition, it is economically impossible, and the original performance of the coating liquid may be impaired due to the large amount of these compounds. Accordingly, the content of the organic dye in the organic dye-containing coating liquid varies depending on the type of the coating liquid, but is preferably 0.001 to 0.1% by weight, particularly preferably 0.005 to 0.05% by weight. .

  On the other hand, the compound that generates active oxygen is not particularly limited as long as it has good generation efficiency of active oxygen and does not affect the performance of the coating solution. An oxo acid salt such as permanganate such as potassium manganate, a general oxidizing agent such as sodium oxide or barium oxide, or a peroxide such as hydrogen peroxide or peroxotitanic acid can be used. These compounds that generate active oxygen may be used alone or in combination of two or more.

  The compound that generates active oxygen is preferably contained in an amount (reaction equivalent) or more that generates active oxygen necessary for oxidative decomposition of the organic dye in the organic dye-containing coating solution. If the content of the compound that generates active oxygen is small, the organic dye in the organic dye-containing coating solution cannot be sufficiently decolored.

  The present invention can be effectively applied to any transparent or translucent coating liquid that becomes colorless after decoloration of the organic dye, regardless of the presence or absence of the photocatalyst. It is useful as a binder coating solution.

  In the case of the photocatalyst coating liquid, the coating liquid further contains a photocatalyst and a binder.

The photocatalyst _{particles, TiO 2, ZnO, SrTiO 3} , CdS, CdO, CaP, InP, In 2 O 3, CaAs, BaTiO 3, K 2 NbO 3, Fe 2 O 3, Ta 2 O 5, WO 3, SnO ₂ , Bi ₂ O ₃ , NiO, Cu ₂ O, SiC, SiO ₂ , MoS ₂ , MoS ₃ , InPb, RuO ₂ , CeO _{2, and the} like may include semiconductor metal fine particles having photocatalytic action. Titanium oxide TiO ₂ fine particles are preferable, and the particle size is preferably about 10 to 500 nm.

  In addition to peroxotitanic acid, binders include silicon compounds such as water glass, colloidal silica and polyorganosiloxane, phosphates such as zinc phosphate and aluminum phosphate, heavy phosphates, and inorganic binders such as cement. (Binder) Organic binders such as fluorinated polymers and silicon polymers can be mentioned. Among these, an inorganic binder that is not affected by the oxidative decomposition action of the photocatalyst is preferable.

  From the organic polymer materials such as acrylonitrile resin, vinyl chloride resin, polycarbonate resin, methyl methacrylate resin (acrylic resin), polyester resin, polyurethane resin, etc., where the substrate on which such a photocatalytic coating solution is applied is decomposed by the photocatalytic activity. In this case, as a coating liquid for forming a hardly decomposable binder layer as an underlayer for protecting the substrate, the substrate can be protected from the decomposition action by the photocatalyst, and the substrate and the photocatalytic film are bonded. In addition to peroxotitanic acid, water glass, colloidal silica, silicon compounds such as polyorganosiloxane, phosphates such as zinc phosphate and aluminum phosphate, and heavy phosphoric acid Inorganic binders (binders) such as salt and cement, fluorinated polymers, silica It can be exemplified a coating solution containing an organic binder, such as emission-based polymer.

  With such an organic dye-containing coating solution of the present invention, the contained organic dye is decolored by active oxygen, and therefore decolored even in a dark place where no ultraviolet rays are applied. However, the organic dye is decomposed not only by active oxygen but also by a photocatalyst. Accordingly, the organic dye-containing coating liquid of the present invention has a slight difference in decoloring speed between the case where ultraviolet rays are irradiated and the case where no ultraviolet rays are irradiated. However, the oxidative decomposition is caused by the photocatalyst disclosed in International Publication WO00 / 33977. Compared with a coating solution containing a colorant that can be erased, the UV dependence of the decoloring speed is greatly reduced, and even if it is not irradiated with UV rays at all, it is usually practical in about one week after coating. Discolor to the extent that there is no problem.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Examples 1-4
In a coating liquid (dispersion medium is 99.0% by weight of ion-exchanged water) containing 0.7% by weight of anatase-type titanium oxide fine particles (average particle size 30 nm) as a photocatalyst and 0.3% by weight of the binder shown in Table 1 An organic dye-containing coating liquid prepared by adding and mixing the organic dye shown in Table 1 and a compound that generates active oxygen so that the concentration in the coating liquid becomes the concentration shown in Table 1 (in Examples 3 and 4) In the coating solution, 0.3% by weight of peroxotitanic acid was blended as a binder and a compound that generates active oxygen.) Was spray-coated on a substrate (white glazed tile) and then naturally dried to form a film. A 0.8 μm thick titanium oxide thin film was formed.

  The base material on which the titanium oxide thin film was formed was left in a dark place not exposed to ultraviolet rays, and its decoloring performance was examined by the following method. The results are shown in Table 1.

<Decolorization performance evaluation>
Compared to the color of the base material when the thin film was formed by leaving the film formed in a dark place for 100 hours, and applying the coating liquid without addition of organic dye to the base material and drying it. The color difference (ΔE) was determined, and when the color difference (ΔE) was 1.5 or less, the decoloring performance passed (◯), and the color difference (ΔE) exceeding 1.5 was regarded as rejected (x).

Table 1 also shows the color difference (ΔE) with respect to the substrate immediately after application of the organic dye-containing coating solution.
The color difference was measured using a color difference meter “CR-400” manufactured by Minolta.

Comparative Examples 1-4
In Examples 1 to 4, except that a compound that generates active oxygen was not blended, an organic dye blend coating solution was prepared in the same manner, and the color erasing performance was similarly examined for the colored titanium oxide thin film formed in the same manner. The results are shown in Table 1.

  From Table 1, in the organic dye-containing coating liquids of Comparative Examples 1 to 4 that do not contain a compound that generates active oxygen, the organic dye is not decomposed even after 100 hours in the dark, and the color difference (ΔE) is almost the same as immediately after application. There is no change, and coloring with organic dyes will last forever, but in accordance with the present invention, by adding a compound that generates active oxygen to the organic dye compounding coating liquid, the organic dye can be decomposed and decolored even in the dark. I understand.

Claims (6)

  An organic dye-containing coating liquid comprising an organic dye that is oxidatively decomposed by active oxygen and a compound that generates active oxygen.   2. The organic dye-containing coating according to claim 1, wherein the organic dye is one or more selected from the group consisting of a cationic methine dye, a triphenylmethane dye, and a triallylmethane dye. liquid.   3. The compound according to claim 1 or 2, wherein the compound that generates active oxygen is one or more selected from the group consisting of hydrogen peroxide, peroxotitanic acid, chlorate, hypochlorite, and permanganate. An organic dye-containing coating solution characterized by   The organic dye-containing coating liquid according to any one of claims 1 to 3, wherein the content of the organic dye is 0.001 to 0.1% by weight.   5. The organic dye-containing coating liquid according to claim 1, which is a photocatalytic coating liquid for forming a photocatalytic film.   6. The organic dye-containing coating liquid according to claim 1, which is a binder coating liquid for forming an underlayer of the photocatalytic film.