JP2007321113A - Powder coating, coating film layer, coating method and coated article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a powder coating that simplifies a process related to coating and sufficiently exhibits photocatalytic performance while preventing decomposition of a synthetic resin to become a main component of a coating film layer by a photocatalytic activity, a coating film layer, to provide a coating method and to obtain a coated article. <P>SOLUTION: The photocatalytic powder 1 comprises a photocatalytic crystal 11 coated with a protective substance 12 more inert to a photocatalyst. Consequently a coating film matrix 2 to become the main component of the coating film is protected by the protective substance 12 and is prevented from being decomposed. A part of the surface of the photocatalytic crystal 11 is coated with the protective substance 12 and other parts are not coated so that photocatalytic performance is developed on the surface of the photocatalytic crystal 11 and photocatalytic performance is sufficiently exhibited. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a powder coating material that can exhibit photocatalytic properties and that can provide a coating film excellent in self-cleaning property, antibacterial property, deodorizing property, decomposability of harmful substances, and the like, and a coating film layer and a coating method using the same And related to painted products.

  The coating film is formed by blending the photocatalytic powder with the powder coating because each is a powder, so that the dispersion state of the photocatalytic powder in the coating is constant compared to the case where the coating is liquid. It is preferable in that it is easy and it is not necessary to strictly manage the dispersion state. However, since the photocatalyst itself exhibits a strong oxidative decomposition action when activated by irradiation with light such as sunlight, it is simply blended with a paint mainly composed of an ordinary synthetic resin to form a coating layer. In this case, the synthetic resin is decomposed by the photocatalyst by irradiation with light, and the function as a coating layer may be impaired. Therefore, as a conventional powder coating material that exhibits photocatalytic properties, for example, a powder coating material that forms a lower layer coating film and an upper layer coating film on an object to be coated, and the upper layer coating material has a photocatalytic action on the fluororesin powder. Disclosed is a coating layer that has an anticorrosion property improved by preventing the deterioration due to the photocatalytic reaction by a lower layer coating layer formed by a powder coating containing titanium oxide powder having (for example, patent) Reference 1).

  Also, a fluorine-containing resin powder coating composition containing the fluorine-containing resin powder coating particles (a) and methylsilicone resin particles (b) encapsulating photocatalytically active titanium dioxide, the particles (a) and The particles (b) are contained substantially independently of each other, and 1 to 25 parts by mass of the particles (b) are contained with respect to 100 parts by mass of the particles (a). A fluorine-containing resin powder coating composition capable of suppressing the deterioration of the fluororesin has been disclosed (for example, Patent Document 2).

Japanese Patent Laid-Open No. 10-130540 JP 2003-176440 A

  However, when the conventional powder coating as described in Patent Document 1 is used, it is necessary to coat the powder coating twice in order to protect the synthetic resin from the photocatalytic activity of the photocatalyst. The process was cumbersome.

  In addition, when the conventional powder coating as described in Patent Document 2 is used, photocatalytic activity is prevented from reaching the fluororesin by encapsulating photocatalytically active titanium dioxide with methylsilicone resin particles. The activity of the photocatalyst is also hindered by the methylsilicone resin particles, and the blended photocatalyst may not exhibit the desired performance.

  The present invention has been made in view of the problems as described above, and the process relating to coating can be simplified while preventing the synthetic resin as the main component of the coating layer from being decomposed by the activity of the photocatalyst, and It is intended to provide a powder coating, a coating layer, a coating method, and a coated product that can fully exhibit the performance of the photocatalyst.

  In order to achieve the above object, the present invention is configured as follows. That is, the powder coating according to the present invention comprises a synthetic resin powder as a main component of the coating film and a photocatalytic powder containing a photocatalytic crystal having photocatalytic properties, and the photocatalytic powder is formed by a photocatalyst. A part of the surface is covered with an inert protective substance.

  According to the powder coating according to the present invention, the photocatalytic crystal is coated with an inert protective substance by the photocatalyst to form a photocatalytic powder, so that the synthetic resin as the main component of the coating film is protected by the protective substance. However, since the protective material covers a part of the surface of the photocatalytic crystal and the other part is not coated, the photocatalytic performance is expressed on the surface of the photocatalytic crystal, and The performance can be fully exhibited.

  The synthetic resin powder may be unsaturated polyester resin powder, saturated polyester resin powder, epoxy resin powder, polyethylene resin powder, polyvinyl chloride resin powder, polyurethane resin powder, polyamide resin powder, polycarbonate resin powder, or polyacetal resin powder. According to the application of the present invention, these synthetic resin powders are often used for powder coating and relatively easily decomposed by the activity of the photocatalyst as long as at least one selected from the group consisting of The advantage can be further enhanced, which is preferable.

  In addition, if the photocatalytic crystal is obtained by substituting a part of a titanium atom or an oxygen atom with a nitrogen atom and / or a sulfur atom, the visible light having a wavelength of 380 nm or more is used for the activity of the photocatalytic crystal to protect it. It is preferable because the reduction of the surface area due to the coating of the substance can be compensated and the performance of the photocatalyst can be more fully exhibited.

  Further, it is preferable that the protective substance is capable of adsorbing bad odor molecules and harmful chemical substances in the air and exhibiting high decomposition performance if it has an ability to adsorb off-flavor molecules or harmful chemical substances.

  In addition, the protective substance does not transmit the molecules of the liquid substance, and if the photocatalytic crystal is coated to such an extent as to transmit the gaseous substance, the photocatalytic performance against gaseous malodor and harmful chemical substances is exhibited. Without hindering, adverse effects on the photocatalytic crystal surface in blending with a synthetic resin can be prevented, which is preferable.

  Furthermore, if it contains a powdery hydrophilizing agent, the photocatalytic activity disappears when the light is no longer irradiated, but the electrons return to the ground state. Even if it is lost, it is preferable because the hydrophilicity expressed by the photocatalytic activity on the surface of the formed coating layer can be maintained and the photocatalytic performance can be maintained.

  Moreover, the coating-film layer concerning this invention is formed using the powder coating material of Claims 1-6, It is characterized by the above-mentioned.

  According to the coating layer according to the present invention, the process relating to the coating can be simplified and the performance of the photocatalyst is sufficient while preventing the synthetic resin as the main component of the coating layer from being decomposed by the activity of the photocatalyst. And can exhibit excellent self-cleaning properties, antibacterial properties, deodorizing properties, decomposability of harmful substances, etc. over a long period of time.

  The coating method according to the present invention is characterized in that the coating layer is formed by the electrostatic powder coating method or the fluidized immersion method using the powder coating material according to claims 1 to 6.

  According to the coating method according to the present invention, it is possible to simplify the process related to coating while preventing the synthetic resin as the main component of the coating layer from being decomposed by the activity of the photocatalyst.

  The coated product according to the present invention is characterized in that a coating film layer is formed on a base material using the powder coating material according to any one of claims 1 to 6.

  According to the coated product of the present invention, the process related to painting can be simplified and the performance of the photocatalyst can be sufficiently achieved while preventing the synthetic resin that is the main component of the coating layer from being decomposed by the activity of the photocatalyst. It can be exhibited and can be a coated product that exhibits excellent self-cleaning properties, antibacterial properties, deodorizing properties, decomposability of harmful substances, etc. over a long period of time.

  According to the powder coating according to the present invention, the photocatalytic crystal is coated with an inert protective substance by the photocatalyst to form a photocatalytic powder, so that the synthetic resin as the main component of the coating film is protected by the protective substance. However, since the protective material covers a part of the surface of the photocatalytic crystal and the other part is not coated, the photocatalytic performance is expressed on the surface of the photocatalytic crystal, and The performance can be fully exhibited.

  The best mode for carrying out the present invention will be specifically described below.

  FIG. 1 shows an embodiment of a coated product according to the present invention, and shows an exaggerated photocatalytic powder of a coating layer formed on a substrate using the powder coating according to the present invention. It is sectional drawing. The coating layer 10 is formed directly on the substrate 20, and the photocatalytic powder 1 is dispersed in a coating matrix 2 formed by melting a synthetic resin powder by heat during baking. Is formed. In the photocatalytic powder 1, a part of the surface of the photocatalytic crystal 11 is coated with a protective substance, so that the coating matrix 2 is prevented from being decomposed by the photocatalytic activity in the part protected by the protective substance 12. At the same time, even if the coating matrix 2 is in contact with the photocatalytic crystal 11, the coating matrix 2 is decomposed by photocatalytic activity in a limited manner at least in contact with the protective matrix. By maintaining the welded portion between 12 and the coating film matrix 2, the deterioration of the coating film layer 10 can be suppressed. Further, the photocatalytic performance of the photocatalytic powder 1 disposed in the vicinity of the surface of the coating layer 10 is exhibited by the surface of the photocatalytic crystal 11 that is not covered by the protective substance 12, and the coating layer 10 is self-cleaning, antibacterial, Useful functions such as deodorization and decomposability of harmful substances are expressed.

Photocatalytic crystals that exhibit photocatalytic properties include Fe ₂ O ₃ , Cu ₂ O, In ₂ O ₃ , WO ₃ , Fe ₂ TiO ₃ , PbO, V ₂ O ₅ , FeTiO ₃ , Bi ₂ O ₃ , Nb _2. Although metal oxide semiconductor materials such as O ₃ , SrTiO ₃ , ZnO, BaTiO ₃ , CaTiO ₃ , KTaO ₃ , SnO ₂ , ZrO ₂ are used, some metal atoms and / or oxygen atoms of these metal oxide semiconductors are used. By using those in which is replaced with a nitrogen atom and / or a sulfur atom, the photocatalytic function can be expressed with respect to visible light of 380 nm or more. Among these, titanium dioxide (TiO ₂ ) can be preferably used as the metal oxide semiconductor material from the viewpoint of cost, workability, and the like. Furthermore, the thing which introduce | transduced metal ions, such as iron and copper, into these nitrogen dope and / or sulfur dope type titanium oxide crystals, and also improved the photocatalytic function can also be used suitably. A part of the surface of these photocatalytic crystals is coated with a protective substance.

  The material for forming the protective substance is not particularly limited as long as it can adhere to the surface of photocatalyst fine particles such as titanium oxide and is inactive with respect to the photocatalytic function of the photocatalyst fine particles. If an object is used to decompose bad odors and harmful chemical substances indoors, the protective substance is formed using an adsorbent that can adsorb bad odors and harmful chemical substances. The substance can be actively adsorbed to exhibit higher decomposition performance. Such adsorbents include inorganic montmorillonite, talc, silica gel, silica sol, silicate, silicon carbide, alumina, zeolite, zirconia, ceramics, apatite, titanium apatite, magnesia, cordierite, sepiolite, calcium hydroxide. Or a complex thereof.

  In order to form the protective substance on the surface of the photocatalytic crystal, the substance for forming the protective substance as described above is dispersed in a solvent such as water, and the photocatalytic crystal is immersed in the solution for an appropriate period of time. By depositing a protective substance on the surface of the crystal in the form of a crystal, or by depositing it as a mask melon-like net structure, or by coating the photocatalytic crystal with a silane coupling agent and then baking at a high temperature It can be formed by a method such as providing pores by vaporizing an organic component contained in the silane coupling agent.

  If the protective material covering a part of the surface of the photocatalytic crystal is too wide, the protective effect of the protective material is reduced, and if it is too narrow, the area where the surface of the photocatalytic crystal is exposed is reduced. Accordingly, the photocatalytic performance of the photocatalytic crystal is less likely to be exhibited, so that the interval between the protective substances is preferably about 0.1 nm to 100 μm, more preferably about 1 nm to 10 μm. By covering at such intervals, the photocatalytic crystal can be coated with the protective substance to such an extent that the gaseous substance can be permeated without passing the molecules of the liquid substance.

  The synthetic resin powder that is the main component of the coating layer may have an appropriate particle size, but preferably has an average particle size of about 1 to 50 μm. The particle size of the photocatalytic powder may be appropriate, but if it is approximately the same as the average particle size of the synthetic resin powder, the dispersibility of the synthetic resin powder can be improved. The average particle size of the photocatalytic powder is preferably about 0.2 to 5 times the average particle size of the powder.

  The synthetic resin powder may be one made of an appropriate synthetic resin, but unsaturated polyester resin powder, saturated polyester resin powder, epoxy resin powder, polyethylene resin powder, polyvinyl chloride, which are often used for powder coating. Resin powder, polyurethane resin powder, polyamide resin powder, polycarbonate resin powder, polyacetal resin powder, and the like are suitable, and these may be used alone or in combination. Furthermore, these synthetic resins are relatively easily decomposed by the photocatalytic activity, and the advantage of applying the present invention can be great.

  The blending amount of the photocatalytic crystal may be an appropriate blending ratio in consideration of the photocatalytic performance and paintability with respect to the synthetic resin powder, but is preferably photocatalytic with respect to 100 parts by weight of the synthetic resin powder. It is preferable to mix 0.5 to 200 parts by weight of the powder, more preferably 5 to 20 parts by weight.

  Moreover, you may mix | blend a powdery hydrophilizing agent with the powder coating material which forms a coating-film layer. By blending the hydrophilizing agent, the hydrophilization by the photocatalytic crystal is sustained by the hydrophilizing agent, and the hydrophilicity related to the photocatalytic performance of the coating layer surface over a much longer time than the case of only the photocatalytic crystal. Can be maintained. The hydrophilizing agent is not particularly limited as long as it exhibits hydrophilicity and is in a powder form. Tetraalkoxysilane in which the alkoxyl group has 4 or less carbon atoms such as a methoxy group and an ethoxy group, , Oligomers obtained by partial hydrolysis thereof, silicates, organosilica sols, and the like can be preferably used.

  As a coating method for forming a coating film layer using these powder coating materials, an appropriate method may be used, but the electrostatic powder coating method or the fluidized immersion method can easily form a dense coating film layer. Is preferred. In the electrostatic powder coating method, an electrostatic force is generated between the synthetic resin powder and the base material to generate electrostatic attraction, and the powder coating is applied to the base material by spraying. The coating film layer is formed by baking at a temperature at which the powder of the material melts. In the fluid immersion method, a synthetic resin powder and a photocatalytic powder are dry blended, and a heated substrate is immersed in a powder coating that is made fluid by, for example, sending air from below in a fluid tank. After the powder coating is adhered, the coating layer is formed by baking at a temperature at which the synthetic resin powder melts.

  For the base material 20 on which the coating layer 10 is formed, an appropriate material may be used. For example, for a structure such as a street fence, a vehicle protection fence, a railing, and an exterior fence in which the base material 20 is used outdoors. As long as it is made of metal, the coating layer 10 may be formed directly on the metal surface, or may be formed by interposing a primer or the like as appropriate in order to improve adhesion.

It is sectional drawing which shows one Embodiment of the coated goods concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photocatalytic powder 11 Photocatalytic crystal 12 Protective substance 2 Coating matrix (formed by powder made of synthetic resin) 10 Coating layer 20 Base material

Claims (9)

It comprises a synthetic resin powder as a main component of the coating film and a photocatalytic powder containing a photocatalytic crystal having photocatalytic properties, and the photocatalytic powder is partially protected by a protective substance that is inactive by the photocatalyst. Powder coating characterized by being coated. The synthetic resin powder is composed of unsaturated polyester resin powder, saturated polyester resin powder, epoxy resin powder, polyethylene resin powder, polyvinyl chloride resin powder, polyurethane resin powder, polyamide resin powder, polycarbonate resin powder, and polyacetal resin powder. The powder coating material according to claim 1, wherein the powder coating material is at least one selected from the group. The powder coating material according to claim 1 or 2, wherein the photocatalytic crystal is obtained by replacing a part of a titanium atom or an oxygen atom with a nitrogen atom and / or a sulfur atom. The powder coating material according to any one of claims 1 to 3, wherein the protective substance is provided with an ability to adsorb off-flavor molecules or harmful chemical substances. The powder according to any one of claims 1 to 4, wherein the protective substance is coated with the photocatalytic crystal so as not to transmit molecules of the liquid substance but to pass through the gaseous substance. paint. The powder coating material according to any one of claims 1 to 5, further comprising a powdery hydrophilizing agent. A coating film layer formed using the powder coating material according to claim 1. A coating method using the powder coating material according to claim 1 to form a coating layer by an electrostatic powder coating method or a fluid dipping method. A coated product, wherein a coating layer is formed on the base material using the powder coating material according to claim 1.

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