JP2013049787A - Photocatalytic coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalytic coating composition at a relatively low cost, which can exhibit preferable flexibility by using an organic resin binder, facilitates adjustment of coated film properties and coating properties than before thereby has preferable versatility, and suitable for industrial production.SOLUTION: On the surface of a steel sheet base material 10, organic layers (an under coat layer (primer) 20, a middle coat layer (coloring layer) 30) and a photocatalyst layer 40 are formed sequentially. The photocatalyst layer 40 includes a photocatalyst particle 401 and a binder component. The binder component is composed of a non-fluorine resin (polyester dispersion component 403) and fluorine-based hydrophilic resin (fluorine-based hydrophilic resin 402 with ≥40% fluorination degree). The photocatalyst particle 401 is protected by the particle 402 and dispersed in the resin component 403.

Description

  The present invention relates to a photocatalyst coating composition excellent in various functions such as productivity, workability, weather resistance, durability and the like.

Recently, a photocatalyst paint (photocatalyst coating composition) containing a photocatalyst material excellent in stain resistance and antibacterial property has attracted attention and is used in a wide range of applications.
In addition, it is desirable that paints used on substrates such as building exterior walls, body steel plates, and tents have a property that contaminants such as rain stains are difficult to adhere to the coating film, that is, have resistance to environmental pollution. ing.

  Here, the photocatalyst coating material is mixed with a binder component for dispersing a metal oxide as a photocatalyst and forming a coating layer after coating and drying. Usually, the photocatalytic reaction with a metal oxide is an intense redox reaction, which decomposes organic substances that are pollutants. When a general resin component is used as the binder component, it is decomposed (self-destructed) by a photocatalytic reaction, and the durability of the coating is reduced, for example, the coating material is peeled off or deteriorated.

Thus, for example, as shown in Patent Document 1, a technique has been developed in which a glassy inorganic binder called silica sol or silicate is used to improve coating film stability.
Further, a perfluorosulfonic acid graft polymer perfluorosulfonic acid graft polymer-PTFE copolymer (Perfluorosulfonic Acid / PTFE copolymer (H ⁺ )), which is an organic resin and is difficult to decompose by a photocatalytic reaction, is an organic resin binder. (For example, refer to Patent Document 2.) In this organic resin binder, chemical stability against a photocatalytic reaction is secured at a C—F bond portion in a molecular structure, and this is used as a molecular skeleton. A coating film having good characteristics can be maintained over a long period of time, and when the organic resin binder is used, the drying time after application can be shortened compared with the case of using an inorganic binder, so that, for example, a high-speed coating such as a color steel plate can be used. Suitable for continuous production, and the coating with inorganic binder is flexible. However, if the substrate on which the coating film is formed is folded, cracks may occur in the coating film. However, the coating film using the organic resin binder has good flexibility and can be folded together with the substrate. There is also a great advantage that a coating film can be formed on a wide variety of substrates.

JP 11-343426 A JP 2006-233073 A

  However, since the organic resin binder described in Patent Document 2 contains a fluororesin as a main component, the characteristics of the fluororesin greatly affect the properties of the composition and the coating film using the composition. The fluororesin is not originally intended for paint, and it is very difficult to adjust the paintability and the physical properties of the coating film using a photocatalyst paint containing a large amount of the fluororesin. Moreover, the base material selectivity to be coated is low and there is a problem in versatility. For example, it is not suitable for industrial production of building exterior materials. Furthermore, commercially available fluororesin solutions are expensive, have a low solid content, and have problems in handling when used as a paint.

  The present invention has been made in view of the above-described problems, and can exhibit good flexibility by using an organic resin binder, and can easily adjust coating film properties and coating properties, and has good versatility. It has an object to provide a photocatalyst coating composition suitable for industrial production at a relatively low cost.

In order to solve the above problems, the present invention includes a binder component containing a fluorine-based hydrophilic resin and a non-fluorine-based resin, and a photocatalyst component, and the photocatalytic component is converted into the fluorine-based hydrophilic resin in terms of a resin non-volatile component. It was set as the photocatalyst coating composition currently disperse | distributed in the said non-fluorine-type resin with the said fluorine-type hydrophilic resin in the protected state.
Here, the fluorine-based hydrophilic resin includes a graft polymer having a sulfonic acid in the side chain of polytetrafluoroethylene, a graft polymer having a carboxylic acid in the side chain of polytetrafluoroethylene, and a side chain of polytetrafluoroethylene. A graft polymer having an amino group at the end, a perfluoroalkyl oligomer having a phosphate ester at the terminal, a perfluoroalkyl oligomer having a sulfonic acid group at the terminal, a perfluoroalkyl oligomer having a carboxylic acid group at the terminal, an amino acid group at the terminal One or a mixture of two or more selected from perfluoroalkyl oligomers and perfluoroalkylethylene adducts can be used.

The non-fluorinated resin may be an aqueous emulsion or an aqueous dispersion, and may be one or a mixture of two or more selected from a polyester dispersion, a polyolefin dispersion, and an acrylate emulsion.
Moreover, it can also be set as the structure which contains fluorine-type hydrophilic resin and non-fluorine-type resin, and the said fluorine-type hydrophilic resin is disperse | distributed in the said non-fluorine-type resin in resin non-volatile component conversion.

As a result of intensive studies on the photocatalyst paint containing the organic resin binder by the present inventors, if the photocatalyst particles are protected with a fluorinated hydrophilic resin, the photocatalyst coating composition can be obtained by dispersing the photocatalyst particles in another non-fluorinated resin. I found out.
Thereby, in the photocatalyst coating composition of the present invention, it is sufficient to use a minimum amount of the fluorinated hydrophilic resin for protecting the photocatalyst, and the influence of the fluorinated hydrophilic resin on the overall properties of the coating film can be suppressed. .

  On the other hand, since the photocatalyst is protected by the fluorinated hydrophilic resin, the contact between the photocatalyst and the non-fluorinated resin is prevented, and the decomposition of the non-fluorinated resin due to the photocatalytic reaction can be reduced. Thereby, even if it uses comparatively many non-fluorine-type resin for a binder component, the self-decomposition of a coating film can be prevented and the characteristic of non-fluorine-type resin can be expressed in a coating film over a long period of time. Therefore, it is possible to maintain a coating film for a long period of time while imparting favorable photocatalytic properties even to a composition mainly composed of a non-fluorine resin that does not have sufficient resistance to a photocatalyst.

Moreover, since the photocatalyst is protected with a fluorine-based hydrophilic resin, it is not necessary to provide a barrier coat on the base of the photocatalyst layer. For this reason, it is possible to provide a photocatalyst layer with what is called 1 coat.
Furthermore, the material cost can be effectively reduced by reducing the amount of the fluorinated hydrophilic resin.

It is a schematic diagram which shows the structure and effect of PCM with a photocatalyst coating film of this invention. It is a figure which shows the structure of PCM (bending PCM) of this invention. It is a flowchart which shows the coating-film formation process using the photocatalyst coating composition of this invention.

Each embodiment of the present invention will be described below, but the present invention is naturally not limited to these forms, and may be appropriately modified and implemented without departing from the technical scope of the present invention. it can.
<Embodiment 1>
(Configuration of baked steel sheet with photocatalyst coating)
FIG. 1A is a schematic cross-sectional view showing the configuration of a photocatalyst-coated baked steel plate 1 (hereinafter referred to as “baked steel plate 1”) according to Embodiment 1 of the present invention.

The baking steel plate 1 is formed by sequentially forming an undercoat layer 20, an intermediate coating layer 30, and a photocatalyst layer (photocatalyst coating film) 40 on one surface of a steel plate 10.
The steel plate 10 is a steel plate having a thickness of 1 mm or less (for example, 0.27 mm), and is a main component of the baked steel plate 1. As a suitable material, a zinc-aluminum alloy plated steel sheet can be exemplified. In this case, as a commercially available product, a “galvalume steel plate” manufactured by Nippon Steel Corporation, which is a zinc-55% aluminum alloy plated steel plate, can be used. Other preferable examples include any of an aluminum-plated steel sheet, a galvanized steel sheet, and a stainless steel sheet. The material of the steel plate 10 is not limited to these. Moreover, the steel plate 10 can also be comprised as a laminated board of a dissimilar metal.

The “steel plate” mentioned in the present invention refers to a general metal plate including various metal materials and alloy materials.
Both the undercoat layer 20 and the intermediate coat layer 30 are organic layers (colored layers) formed by baking an organic paint.
The undercoat layer 20 corresponds to the first layer of the colored layer, and is a primer layer having a thermosetting resin as a main component and a thickness of about several μm (for example, about 2 μm). It is provided mainly for the purpose of improving the coating film durability of the intermediate coating layer 30 in the baked steel sheet 1. Moreover, it may be provided for the purpose of ensuring the color developability of the intermediate coating layer 30 and providing a rust prevention function or a heat shielding function. In this case, a function-imparting agent such as a color former or a rust preventive is added to the thermosetting resin. Moreover, an antifoamer, a leveling material, a pigment, etc. can be added.

Known materials can be used for the thermosetting resin, and examples thereof include polyester resins, epoxy resins, and resins containing these. Moreover, a well-known material can be utilized also as a hardening | curing agent, An amino material and a polyisocyanate type material can be illustrated.
The intermediate coating layer 30 is a main colored layer (baked coating film) of the baked steel sheet 1 and includes a predetermined pigment component and a resin material that is in good contact with the undercoat layer 20. The thickness of the intermediate coating layer 30 is adjusted within a range in which sufficient color development is obtained and peeling does not occur during processing. Specifically, it can be set to several to several tens of μm as an example. As other components, it may also include a gloss adjusting material, a matting material, an antifoaming agent, and the like.

  A known material can also be used for the resin material of the intermediate coating layer 30. For example, a polyester resin, a fluorine resin, an acrylic resin, a urethane resin, an epoxy resin, or the like can be used as a resin material that can be expected to improve colorability and corrosion resistance. As a guideline for selecting these resin materials, a material that can be applied to a so-called coil coating line that is continuously applied to a steel plate and baked is selected. Here, the polyester resin is particularly desirable because it satisfies these requirements well.

The photocatalyst layer 40 is a main characteristic part of the baked steel sheet 1 and is a photocatalyst coating film containing photocatalyst particles 401 and binder components (fluorine-based hydrophilic resin particles 402 and non-fluorine-based resin components 403). Although the film thickness of the photocatalyst layer 40 can be adjusted as appropriate, it can be set to 0.5 μm or more and 5 μm or less as an example.
Here, FIG.1 (b) is the elements on larger scale of Fig.1 (a). As shown in the drawing, in the photocatalyst layer 40, the fluorinated hydrophilic resin particles 402 are dispersed in the non-fluorinated resin component 403 in a state where the photocatalyst particles 401 are protected. As described above, the binder component is configured to include a fluorine-based hydrophilic resin and more non-fluorine-based resin than the fluorine-based hydrophilic resin.

By protecting the photocatalyst particles 401 with the fluorine-based hydrophilic resin particles 402, decomposition of the non-fluorine-based resin component 403 due to the photocatalytic reaction is prevented. Therefore, in the photocatalyst layer 40, it is possible to stably use a large amount of the non-fluorine resin component 403 and to positively exert the characteristics of the non-fluorine resin component 403 in the overall coating film characteristics.
Next, specific examples of the binder component are shown. In the photocatalyst layer 40, a polyester dispersion is used as the non-fluorine resin, and a fluorine-based hydrophilic resin having a degree of fluorination of 40% or more is used as the fluorine-based resin. By using these resin materials, the photocatalyst layer 40 can be formed by baking coating in the PCM1.

  The blending ratio of the fluorinated hydrophilic resin and the non-fluorinated resin can be appropriately adjusted. However, as shown in FIG. 1 (a), at least the non-fluorinated resin component (polyester dispersion component) 403 is fluorinated. It adjusts so that resin (fluorine-type hydrophilic resin particle 402) may be disperse | distributed. Specifically, in the binder component, the conversion ratio of the polyester dispersion and the fluororesin is in a range of 20: 1 to 1: 1 in terms of a resin non-volatile component, and the fluororesin and the photocatalyst The blending weight ratio is set to be in the range of 1: 6 to 3: 1.

  Next, as the resin constituting the fluorinated hydrophilic resin particle 402, a graft polymer having sulfonic acid in the side chain of polytetrafluoroethylene (PTFE) and a graft polymer having carboxylic acid in the side chain of polytetrafluoroethylene are used. Polymer, graft polymer having amino group at the side chain of polytetrafluoroethylene, perfluoroalkyl oligomer having phosphate ester at the end, perfluoroalkyl oligomer having sulfonic acid group at the end, perfluoroalkyl oligomer having terminal carboxylic acid group Examples thereof include one or a mixture of two or more selected from fluoroalkyl oligomers, perfluoroalkyl oligomers having an amino acid group at the terminal, and perfluoroalkylethylene adducts.

Since the photocatalytic reaction is fundamentally a decomposition reaction of water, the photocatalytic layer 40 uses such a fluorine-based hydrophilic resin as a binder component so that the reactive species water can easily concentrate in the vicinity of the photocatalytic particles 401. Yes.
In addition, if a fluorine-type hydrophilic resin is contained in the said mixture ratio, other fluororesins, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene copolymer A mixture of one or more of the vinylidene fluoride-hexafluoropropylene copolymers may be contained in the photocatalyst layer 40.

  The fluorine-based hydrophilic resins that can be used in the present invention are diverse, but as a result of strict examination by the inventors of the present application, a suitable amount of a predetermined fluorine resin is added to the photocatalyst layer 40 on the basis of the above-mentioned blending ratio. In addition to exhibiting sufficient durability against the reaction, it is possible to effectively suppress deterioration of the polyester dispersion coexisting as the binder component and the intermediate coating layer 40 while maintaining the photocatalytic function. Yes.

  Generally, a fluororesin has abundant C—F bonds and is chemically stable. Specifically, the bond energy of the C—F bond is sufficiently large (about 500 kJ / mol) for any bond energy of the C—H bond (415 kJ / mol) and the C—C bond (347 kJ / mol). . Therefore, a chemically stable molecular chain can be formed by using a fluororesin. Due to this chemical stability, in the present invention, the photocatalyst layer 40 can be stably held for a long time without being subjected to the decomposition reaction by the photocatalyst particles 401. In addition, the fluororesin has a high degree of crystallinity, can form a very dense crystal structure, exhibits excellent chemical resistance and weather resistance, and is highly stable against electrochemical reactions. In addition to this, it also has the properties of low surface tension and low friction coefficient, because the F atom has a small atomic radius and low polarizability, so it has low intermolecular cohesion and excellent flexibility. Possible (Refer to page 306 of the Encyclopedia of Plastics and Functional Polymer Materials: Issued by the Industry Research Association Encyclopedia Publishing Center (2004)).

The polyester dispersion is an example of the non-fluorine resin component 403, and is used for imparting high flexibility and workability.
On the other hand, the fluorine-based hydrophilic resin particle 402 is composed of an amphoteric resin that exhibits hydrophilicity in a sulfonic acid group or a carboxylic acid group and exhibits hydrophobicity in other portions. Therefore, in order to disperse the fluorinated hydrophilic resin particles 402 in the non-fluorinated resin component 403, the non-fluorinated resin needs to be compatible with the fluorinated hydrophilic resin.

  As a result of intensive studies by the inventors of the present application on this point, a water dispersion resin exhibits good compatibility with a fluorinated hydrophilic resin, and by using a predetermined amount of the water dispersion resin, It has been found that the binder component can be constituted. Thereby, the photocatalyst coating material excellent in coatability can be constituted, and the photocatalyst layer 40 having excellent performance even after the coating film is formed is realized.

Examples of the non-fluorine resin component 403 include one or a mixture of two or more selected from olefin dispersions in addition to the above polyester dispersion.
Next, the kind of photocatalyst particle 401 is not particularly limited. For example, one or more metal oxides selected from TiO ₂ , ZnO, WO ₃ , SnO ₂ , SrTiO ₃ , Bi ₂ O ₃ , and Fe ₂ O ₃ can be given. Of these, titanium oxide (TiO ₂ ) is suitable because it has a stable photocatalytic function, is readily available, and has many commercial products. Although the form of the photocatalyst at the time of adding to the photocatalyst layer 40 is not limited, when the photocatalyst particle 401 having a uniform particle diameter is used, a uniform photocatalytic function can be expected in the entire photocatalyst layer 40. Specifically, the photocatalyst particles 401 may be dispersed in the catalyst layer 40 as secondary and tertiary particles in which primary particles having an average particle size of about 7 nm are aggregated to an average particle size of about 200 to 300 nm. . The addition amount of the photocatalyst particles 401 to the photocatalyst layer 40 can be appropriately adjusted according to the photocatalyst effect desired to be exhibited. For example, the photocatalyst layer 40 can be added at a rate of 5 to 80 wt%.

  The photocatalyst particles 401 are protected by the fluorinated hydrophilic resin particles 402 and are dispersed in the non-fluorinated resin component 403 together with the fluorinated hydrophilic resin particles 402. This facilitates the photocatalytic reaction using water as a reactive species, and makes use of the strong CF bond of the fluorinated hydrophilic resin particle 402 to eliminate unnecessary self-decomposition reaction of the catalyst layer 40 by the photocatalytic reaction. This is to appropriately prevent this.

  In the present invention, the photocatalyst particles 401 are protected by the fluorinated hydrophilic resin particles 402. However, the protected photocatalyst particles 401 may be in the form of primary particles, secondary particles, or tertiary particles. The photocatalyst particles 401 or the 401 particle groups are protected by the fluorinated hydrophilic resin particles 402. Furthermore, the meaning of “protection” is to be interpreted broadly, and when the particles 401 are supported on the surface of the fluorinated hydrophilic resin particles 402 in addition to the case where they are contained inside the fluorinated hydrophilic resin particles 402. Including.

In order to obtain a good photocatalytic effect, it is preferable to provide the catalyst layer 40 as the uppermost layer in the baked steel sheet 1.
(About the effect of the baked steel sheet 1)
In the photocatalyst layer 40 of PCM1 having the above-described configuration, a minimum amount of fluorine-based hydrophilic resin particles 402 is used for the purpose of protecting the photocatalyst particles 401, and the non-fluorine-based resin component 403 is replaced with fluorine-based hydrophilic resin particles. More than 402 is contained. For this reason, the characteristic of the non-fluorine-based resin component 403 is predominantly exhibited as the entire coating film characteristic of the photocatalyst layer 40. In the first embodiment, since the polyester dispersion is used as the non-fluorine resin component 403, the characteristics of the polyester dispersion are also effectively exhibited in the photocatalyst layer 40.

  Specifically, the photocatalyst layer 40 exhibits a high degree of flexibility and extensibility by containing a relatively large amount of polyester resin. As a result, even when the baked steel sheet 1 is deformed by press working or the like, the photocatalyst layer 40 is also flexibly bent following the deformation of the steel sheet 10 and does not easily peel or lose. Such followability / workability is an advantage that cannot be seen in a photocatalyst layer using only inorganic materials as in Patent Documents 1 and 2, and is almost subject to restrictions on workability and aesthetic adjustment of the baked steel sheet 1. And can demonstrate excellent productivity.

Further, in the photocatalyst layer 40, since an expensive fluorine-based hydrophilic resin is used as the particles 402 in a necessary minimum amount, the material cost can be effectively reduced, and a coating film can be easily formed on a large area.
As described above, the photocatalyst layer 40 can achieve various effects at a low cost by adjusting the coating film properties, coating properties, and the like.

  On the other hand, since the photocatalyst layer 40 contains the photocatalyst particles 401 and the fluorinated hydrophilic resin particles 402, the photocatalytic effect is exhibited by these configurations. That is, when water adheres to the surface of the photocatalyst layer 40 during use, a flat water film is formed on the entire surface of the photocatalyst layer 40 due to the effect of the fluorinated hydrophilic resin particles 402. The state at this time is shown in FIG. FIG.1 (c) is an expanded sectional view of the area | region B in the vicinity of the photocatalyst layer 40 surface of Fig.1 (a).

  In such a state, lipophilic contaminants (such as smoke particles contained in rain) adhere to the photocatalyst layer 40. Here, as shown in FIG. 1C, when moisture adheres to the surface of the photocatalyst layer 40, a water film is quickly formed by the effect of the fluorinated hydrophilic resin particles 402. As a result, the contaminants float on the surface of the water film and flow away with the water. Based on the same principle, if raindrops adhere to the surface of the photocatalyst layer 40 after the contaminants have adhered, a water film is formed and the contaminants can be removed.

  On the other hand, the photocatalyst particles 401 protected by the fluorine-based hydrophilic resin particles 402 are excited by light irradiation from the outside. By this excitation, in the vicinity of the surface of the photocatalyst layer 40 close to the atmosphere, oxygen in the atmosphere receives energy from the photocatalyst and changes to active oxygen. Active oxygen acts on the surface of the photocatalyst layer 40 or in the vicinity thereof to decompose lipophilic contaminants, weaken adhesion, and be easily removed. Thereby, even if rain hits the photocatalyst layer 40, contaminants are easily washed away.

  Furthermore, the photocatalytic layer 40 has a very low friction coefficient and good wear resistance due to the addition of the fluorine-based hydrophilic resin particles 402, and can suppress surface friction during external contact to a very low level. As a result, even if there is some external contact, damage or omission of the photocatalyst layer 40 can be avoided, and a long-term photocatalytic function can be expected. This is particularly effective when the PCM 1 is used for the exterior of home appliances.

In Patent Documents 1 and 2, it is described that an organic binder component cannot be added to the photocatalyst coating film by a photocatalytic reaction, but the present invention is a fluorine-based hydrophilic having a degree of fluorination of 40% or more, which is extremely excellent in chemical stability. Resin is used as a binder component. Thereby, the photocatalyst layer 40 that can withstand a severe photocatalytic reaction is realized, and in this respect, it has a significant advantage over the prior art.
(About the photocatalyst coating composition of the present invention and the photocatalyst layer using the same)
Conventionally, in a photocatalytic coating composition using an organic binder, a fluorine-based hydrophilic resin such as polytetrafluoroethylene-sulfonic acid is used as a main component of the organic binder as a photocatalytic reaction protective material. However, since the fluorine-based hydrophilic resin is not a coating resin, there is a problem that the physical properties of the coating film and the coating properties can hardly be adjusted. In addition, there is a problem that the material is expensive and has versatility such as substrate selectivity, and is not particularly suitable for industrial production.

In contrast, in the photocatalyst coating composition of the present invention, the photocatalyst material is protected with a minimum amount of a fluorinated hydrophilic resin, and this is dispersed in a non-fluorine resin to obtain a high concentration photocatalyst dispersion.
In this composition, a non-fluorine resin can be used, and more non-fluorine resin can be used than a fluorine-based hydrophilic resin. Therefore, the characteristics of the non-fluorine resin can be effectively utilized in the coating film.

Examples of the non-fluorine resin include water-based resins or water-dispersible resins. Specific liquids using water-dispersed resins include water-based emulsions, aqueous dispersions (particularly ethylene-based, urethane-based, styrene-based, etc.). Ionomer resin).
By setting the photocatalyst coating composition to such a composition, in the present invention, it is possible to realize both the physical properties of the coating film, the paintability and the photocatalytic performance.

Here, the photocatalyst coating composition of the present invention has excellent water resistance, and even when a coating film is formed on a product around a bathroom or kitchen, a good photocatalytic effect can be expected over a long period of time. In general, since a hydrophilic coating film is inferior in water resistance, it is expected that the photocatalyst coating composition of the present invention can be expected to have very high utility when it exhibits water resistance.
Moreover, according to this invention, the versatility of a photocatalyst coating composition can also be expanded greatly. For example, by appropriately selecting a non-fluorine resin, the coating film can be cured by either natural drying, baking (thermosetting reaction), or a curing reaction using active energy rays such as UV or EB. it can. Thus, since the coating film can be cured by a method other than baking coating, the material of the substrate is not selected. For example, it is possible to form a coating film on various substrates such as plastic substrates, resin films such as PET films, wood processed products, metals and the like that are difficult to be baked. Thereby, the photocatalyst coating composition can be used for any of exterior, interior, home appliances, and other processed products, and industrial productivity can be dramatically improved.

Further, since an expensive fluorinated hydrophilic resin is used at a minimum, it is useful in that the material cost can be reduced as much as possible.
Furthermore, since the photocatalyst coating composition can improve the paintability by adding a non-fluorine resin, a wide variety of coating methods can be selected. For example, painting using brushes, sprays, and various coaters is possible.

Furthermore, since a known pigment and colorant can be added to the photocatalyst coating composition, it is also possible to form a coating film as a colored layer.
Further, as described above, the photocatalyst component is protected by the fluorinated hydrophilic resin, and the C—C bond of the non-fluorinated resin is not excessively damaged by the intense photocatalytic reaction. For this reason, a coating film can be maintained over a long period of time, and a favorable photocatalytic effect can be expected. The photocatalytic effect in this case is not limited to antifouling properties, and for example, effects such as deodorization, antibacterial activity, antiviral activity, and antistatic property can be expected. These effects are particularly useful when the photocatalytic coating composition of the present invention is applied to the interior.

Moreover, in the photocatalyst coating composition of this invention, the coating film thickness can be formed comparatively thick (for example, film thickness of 20 micrometers or more). This is due to the non-fluorine resin and has the advantage of wear resistance.
Conventionally, there is a composition in which a photocatalyst component is included with calcium phosphate or the like and dispersed in a resin binder (see, for example, Japanese Patent No. 3487336). However, this configuration has the disadvantage of significantly reducing the photocatalytic surface area. In this respect, it is greatly different from the present invention.

Hereinafter, other embodiments of the present invention will be described focusing on differences from the first embodiment.
<Embodiment 2>
In the photocatalyst coating composition of the present invention, a non-fluorinated resin constituting the binder component can be appropriately selected. For this reason, a coating film can be formed also by methods other than the baking process, and a coating film can be arrange | positioned to the base material of a wide material.

FIG. 2 shows a schematic cross-sectional view of a photocatalyst-coated substrate 1A, which is Embodiment 2 of the present invention. The configuration shown in this figure is formed by forming a photocatalyst layer 40 on one surface of a plastic substrate 10A.
In this configuration, in the binder component of the photocatalyst coating composition, an ultraviolet curable acrylic resin (as an example, allyl methacrylate) is used as the non-fluorine resin component. When forming a coating film, a paint is applied to the surface of the substrate and then irradiated with ultraviolet rays using a UV lamp. Thereby, a binder component hardens | cures and the photocatalyst layer 40 is formed.

As described above, in the second embodiment, the photocatalyst layer 40 can be formed relatively easily with a UV lamp. Therefore, for example, the photocatalyst layer 40 can be easily disposed as an aftercoat on the inner wall of the bathroom.
Needless to say, the base body 10A is not limited to a plastic product, and may be made of other materials, such as a processed wood product or a metal plate.
<Example of preparation of photocatalyst coating composition>
Hereinafter, specific adjustment examples and coating examples of the photocatalyst coating composition of the present invention will be described based on the adjustment flowchart of FIG. 3 and Tables 1 to 5.

First, as shown in FIG. 3, as an adjustment step, a photocatalyst and a fluorinated hydrophilic resin are mixed to prepare a dispersion (mixing step S1). As a result, the photocatalyst is included in the fluorine-based hydrophilic resin.
Table 1 shows a configuration example of the high concentration photocatalyst / Nafion (registered trademark) dispersion. Here, typical commercially available titanium oxide particles are used as the photocatalyst particles, but various titanium oxides or other metal oxides that are photocatalysts can be replaced as necessary as described later.

  Next, a non-fluorinated resin, a predetermined solvent, a polymerization initiator, a dispersant, and the like are added to the prepared dispersion and mixed (mixing step S2). At this time, the dispersion is dispersed in a relatively large amount of non-fluorinated resin. As a result, as shown in FIGS. 1A and 1B, the photocatalyst particles are supported on the fluorinated hydrophilic resin particles, and the fluorinated hydrophilic resin particles are further dispersed in the non-fluorinated resin component. The photocatalytic coating composition of the present invention can be obtained.

  Next, Tables 2 to 6 show specific composition examples of the composition prepared in the mixing step S2, but the present invention is naturally not limited to these compositions. In each table, “phr” represents the pigment weight relative to 100 g of resin solids. For example, “50 phr” indicates that 50 g of pigment is added to 100 g of resin solid content. In addition, the parentheses indicate weight% (resin non-volatile component conversion) as the remaining heating amount. "Paint weight range%" indicates a preferred added weight range of each component in the composition.

Note that in any composition, the photocatalytic protection effect is lowered when the amount of the fluorinated hydrophilic resin is too small, and the photocatalytic activity is lowered when the amount of the photocatalyst is small.
Table 2 shows composition examples for PCM baking coating suitable as the catalyst layer 40 of the first embodiment. In Table 2, “200 phr (ST01 / Nafion)” at the top indicates the dispersion prepared in Table 1.

The composition of Table 3 shown below is the composition of the indoor environment type photocatalyst paint. For example, it can be used as a functional paint for interiors, and can be expected to decompose VOC gas, deodorize, and have an antibacterial effect.
In Tables 3 to 6, “200 phr (sulfur-doped titanium oxide / T-Nafion)” refers to a dispersion prepared by replacing the titanium oxide of Table 1 with sulfur-doped titanium oxide.

  The structure of Table 4 shown below is the composition of the active energy ray-curable coating material. Since this composition is cured using a photopolymerization reaction, it can be cured using, for example, an electron beam or a UV lamp. Therefore, similarly to Table 3, it is suitable for forming a coating film on a substrate that is difficult to be baked, and can be used as a functional paint for interior.

  The composition of Table 5 shown below is the composition of the photocatalytic wax.

After the composition is adjusted as described above, it is applied to a predetermined substrate surface (application step S3).
And if the drying process S4 (baking process in the case of the composition of Table 2, 5) is implemented as needed, a base | substrate with a photocatalyst coating film will be completed.
<Other matters>
The binder component in the photocatalytic coating composition of the present invention can form a coating film alone. In general, water-soluble paints are inferior in water resistance, light resistance, and antistatic properties. However, coating compositions and coating films formed using the binder component of the present invention are excellent in water resistance and antifogging properties, and are widely used. It can be used for various purposes.

  For photocatalyst coating materials, select from inorganic UV absorbers such as zinc oxide, titanium oxide, and cerium oxide, organic UV absorbers such as benzotriazole, salicylic acid, and benzophenone, and light stabilizers such as hindered amines. A compound to be prepared may be added. Thereby, the photocatalyst layer 40 is provided with an ultraviolet ray preventing function.

  The photocatalyst coating composition of the present invention is provided with a photocatalyst coating film such as a building material such as a siding, a house door, a partition panel, a locker, a rice bran, a switchboard, a steel desk, a bench, and an exterior of an electric appliance such as a cooler or a refrigerator. Can be used for baking steel sheets. In addition, it can be applied to the surface of plastic products and wood processed products that cannot be baked, and its industrial applicability is extremely wide.

1 Base with photocatalyst coating (baked steel plate with photocatalytic coating)
1A Substrate with a photocatalytic coating (plastic base with a photocatalytic coating)
10 Base material (steel plate)
10A base material (plastic base)
20 Colored layer (undercoat layer)
30 Colored layer (intercoat layer)
40 Photocatalyst layer 401 Photocatalyst particles 402 Fluorophilic hydrophilic resin particles (fluorinated hydrophilic resin particles having a degree of fluorination of 40% or more)
403 Non-fluorine resin component (polyester dispersion component)

Claims (4)

A binder component containing a fluorine-based hydrophilic resin and a non-fluorine-based resin, and a photocatalytic component,
A photocatalyst coating composition, wherein the photocatalyst component is dispersed in the non-fluorine resin together with the fluorinated hydrophilic resin in a state where the photocatalyst component is protected by the fluorinated hydrophilic resin in terms of a resin non-volatile component. . The fluorine-based hydrophilic resin is
A graft polymer having a sulfonic acid in the side chain of polytetrafluoroethylene, a graft polymer having a carboxylic acid in the side chain of polytetrafluoroethylene, a graft polymer having an amino group in the side chain of polytetrafluoroethylene, and a terminal Perfluoroalkyl oligomer with phosphate ester, perfluoroalkyl oligomer with sulfonic acid group at the end, perfluoroalkyl oligomer with carboxylic acid group at the end, perfluoroalkyl oligomer with amino acid group at the end, perfluoroalkylethylene addition The photocatalyst coating composition according to claim 1, wherein the photocatalyst coating composition is one or a mixture of two or more selected from among the above.   The non-fluorine-based resin is an aqueous emulsion or an aqueous dispersion, and is one or a mixture of two or more selected from a polyester dispersion, a polyolefin dispersion, and an acrylate emulsion. Or the photocatalyst coating composition of 2. Including fluorine-based hydrophilic resin and non-fluorine-based resin,
The coating composition, wherein the fluorine-based hydrophilic resin is dispersed in the non-fluorine-based resin in terms of a resin non-volatile component.

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