JP2003171601A - Antibacterial photocatalytic coating material and antibacterial photocatalytic member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antibacterial photocatalytic coating material which is made by using a photocatalyst comprising a low-cost perovskite type oxide capable of exhibiting a photocatalytic activity in a visible light region based on a simple new mechanism, and using' an aqueous solvent, and which has antibacterial, mildewproofing and alga-preventive effects as well as hot-water resistance and alkali resistance, and to provide an antibacterial photocatalytic member. <P>SOLUTION: The antibacterial photocatalytic coating material contains a silicone acrylic emulsion coating, an aqueous solvent and a photocatalyst, wherein the photocatalyst comprises a perovskite type oxide capable of dissolving and holding hydrogen in the form of hydrogen ions through the holes produced by doping with an acceptor, is represented by general formula (I): A<SP>2+</SP>B<SP>4+</SP><SB>1-x</SB>C<SP>3+</SP><SB>x</SB>O<SB>3-</SB>δ (wherein 0<X≤0.5 and 0<δ<0.5), and comprises a perovskite type oxide doped with up to 50 mol% of the cation C having an ionic valence lower than that of the ion B. The antibacterial photocatalytic member is obtained by using the coating material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial photocatalyst paint and an antibacterial photocatalytic member having antibacterial, antifungal and antialgal action.

[0002]

2. Description of the Related Art Antibacterial photocatalytic paints include organic paints and inorganic paints. Antibacterial organic coatings containing an antibacterial agent in an organic resin deteriorate the resin when used for a long time, and especially when used outdoors, stains adhere to the surface and deterioration due to ultraviolet rays causes There is a drawback that performance tends to decrease. On the other hand, inorganic coatings containing an antibacterial agent in a silicate-based, phosphate-based, or zirconium-based inorganic composition have better durability than the above-mentioned organic coatings, but all require baking at a high temperature of 200 ° C or higher. Therefore, it is difficult to apply a coating directly to building materials and plastics, and the usable range is limited. Japanese Patent No. 2776259 discloses an inorganic coating composed of a silicon compound and / or colloidal silica, and an antibacterial photocatalytic inorganic coating containing an antibacterial agent.
There is disclosed an inorganic coating which can be baked at 200 ° C. or lower, has flexibility, and can maintain antibacterial performance for a long period of time. However, since a silicon compound is used as a binder, it has a drawback of being inferior in hot water resistance and alkali resistance.Also, in this inorganic paint, it is dispersed in a non-aqueous organic solvent such as alcohol, but recently, due to environmental problems, a solvent is used. There is an increasing demand for antibacterial photocatalyst paints that are not used.

As a material exhibiting antibacterial properties, a coating material containing titanium oxide in the coating film and having a self-cleaning function has recently been attracting attention. When a coating film is formed using this paint, the anatase-type titanium oxide in the coating film absorbs the ultraviolet rays contained in the sun rays to generate electrons and holes.
Since the generated holes have strong oxidizing power, they decompose organic substances and the like adhering to the surface of the coating film, thereby preventing contamination of the coating film surface with organic substances.

However, titanium oxide exhibits its performance as a photocatalyst only for ultraviolet rays. Since ultraviolet rays make up only about 4% of the sun's rays outdoors, it is generated by absorbing a visible light by adsorbing a pigment on titanium oxide with the aim of making titanium oxide highly functional and responsive in the visible light range. The method of injecting electrons into the titanium oxide from the excited state of the adsorbed dye, the method of chemically injecting metal ions such as Cr, V, Mn, Fe, and Ni, the method of introducing oxygen defects by plasma irradiation, and the different ions Various attempts have been made domestically and internationally, such as the method of introduction. However, none of these methods has been industrialized because of problems such as difficulty in uniform dispersion, reduction of photocatalytic activity due to recombination of electrons and holes, and high adjustment cost.

In addition, recently, perovskite type oxidation
It is noted that the product has catalytic activity. For example,
In Japanese Patent Laid-Open No. 7-24329, the general formula A³⁺B
³⁺O ₃LaFeO₃And the general formula A²⁺B³⁺Ox
SrMnOx, etc. have been proposed, but high catalytic activity
Has not been obtained. In addition, the layered perovskite type
Research on oxides is also actively conducted. For example, JP-A-1
0-244164 discloses a layered perovskite type A
BCO_FourAre described in Japanese Patent Application Laid-Open No. 8-196912.
The publication states that KLaCa₂Nb₃O_TenBased complex oxides are described
Japanese Patent Application Laid-Open No. 11-139826 discloses KC.
a₂Nb₃O_TenIs proposed. These principles and manufacture
The method is complicated and the chemical stability of the resulting oxide is
However, it has not been industrialized due to problems.

[0006]

DISCLOSURE OF THE INVENTION The present invention uses an inexpensive perovskite-type oxide photocatalyst that exhibits photocatalytic activity based on a simple new mechanism in the visible light region, and uses a water-based solvent to obtain hot water resistance. It is intended to provide an antibacterial photocatalyst coating and an antibacterial photocatalytic member having antibacterial, antifungal, and algae-proof properties, which also have antibacterial properties and alkali resistance.

[0007]

The first invention of the present invention is as follows:
Silicon acrylic emulsion paint, aqueous solvent and photocatalyst
It is an antibacterial photocatalyst paint containing
Via the holes created by doping the
Pero capable of dissolving and holding hydrogen as hydrogen ions
A skeleton type oxide having the general formula (I): A²⁺
B⁴⁺ _1-xC³⁺ _xO _3-δ (0 <X ≦ 0.5 and 0 <δ <
0.5), a cation C having a lower valence than B ion
Perovskite-type acid doped up to 50 mol%
And A is selected from alkaline earth metal elements
One or more elements, B is a lanthanoid, and IVa,
One or more selected elements selected from IVb group elements
Yes, C is from lanthanoids and IIIa, IIIb group elements
It is a photocatalyst that is one or more selected elements.
An antibacterial photocatalyst coating is provided.

A second invention is the antibacterial photocatalyst paint according to the first invention, wherein the silicone acrylic emulsion paint containing the photocatalyst is a composite of polyorganosiloxane and acrylic polymer. provide.

A third invention provides the antibacterial photocatalyst paint according to the first or second invention, wherein the paint containing the photocatalyst is a room temperature crosslinking type.

In a fourth invention, the photocatalyst is represented by the general formula
In the perovskite type oxide of (I), A is C
a, Sr, Ba, B is Zr, Ce, and C ions to be doped at the B site are Y, Ga, and In ions, and the antibacterial photocatalyst paint according to the first invention is provided. To do.

A fifth aspect of the present invention provides the antibacterial photocatalyst coating material according to any one of the first to fourth aspects, wherein the photocatalyst carries an antibacterial metal.

A sixth invention is an antibacterial photocatalytic member characterized in that the antibacterial photocatalytic coating composition according to any one of the first to fifth inventions is applied to a substrate and cured to form an antibacterial photocatalytic film. is there.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. In the present invention, the general formula (I): A ²⁺ B ^{4 +} _1-x C ³⁺ _x O _3- δ (0 <X
A perovskite type oxide represented by ≦ 0.5 and 0 <δ <0.5) was generated by doping the B ion site with a cation C having a lower valence than the B ion as an acceptor. Since it has the ability to dissolve and hold hydrogen as hydrogen ions through holes, the energy band gap is constant as it was before the cation was doped, but the acceptor level generated by doping and the cation C doping It is possible to control the wavelength range of light acting as a photocatalyst by utilizing the order of impurities caused by the external atmosphere in which the generation is promoted, and as a result, it is possible to effectively act also on visible light. It is a feature.

The oxide of the perovskite structure represented by the general formula ABO ₃ (perovskite oxide) is well known, but strictly speaking, the perovskite structure has a cubic unit lattice and belongs to the space group Pm3m. There are not so many oxides having this structure. In many perovskite type oxides, the unit cell is distorted and deviated from the cubic unit cell, and is therefore called a perovskite type oxide.

The general formula containing alkaline earth elements A ²⁺ B ⁴⁺
_1−x C ³⁺ _x O ₃₋ δ (0 <X ≦ 0.5 and 0 <δ <0.
In the perovskite type oxide represented by 5), B
It is known that when the ion site is doped with a cation C having a lower valence, hydrogen is dissolved as an ion through the generated holes, so that it becomes a high temperature proton (hydrogen ion) conductor at 600 ° C. or higher. There is. The present inventors have found that when such an oxide is used as a photocatalyst, the number of hydrogen ion dissolution sites is large and active, so that the photocatalytic activity dramatically increases. In addition, since it becomes possible to excite electrons through the impurity level caused by the external atmosphere, the generation of which is promoted by the doping of the cation C, it has an effective photocatalytic action with visible light having an energy lower than the band gap energy. It becomes possible to provide the material. Here, A is one or more elements selected from alkaline earth metal elements, B is a lanthanoid, and one or more elements selected from Group IVa and IVb elements, and C
Is a lanthanoid and one or more elements selected from the group IIIa and IIIb elements, preferably A is Ca, Sr, Ba, B is Zr, Ce, and the B site is doped. It is desirable that the C ions are Y, Ga and In ions.

Regarding the doping amount of the cation C having a valence lower than that of the B ion doped as an acceptor at the B ion site, the above-described general formula A ²⁺ B ^{4 +} _1-x C ³⁺ _x O _3-
It is advisable to set the range to a maximum of 50 mol% as shown by δ (where 0 <X ≦ 0.5 and 0 <δ <0.5). This is because if the doping amount of the cation C exceeds 50 mol%, a different phase may be precipitated and the photocatalytic performance may be deteriorated. Incidentally, δ in the above general formula is a value which varies depending on the conditions of oxygen partial pressure during the production of the perovskite oxide. Then, when the value of δ exceeds 0.5, the heterophase is precipitated and the photocatalytic performance is deteriorated. Therefore, the condition of oxygen partial pressure at the time of production is adjusted and the value is set within the range of 0 <δ <0.5. It

Here, the general formula A ²⁺ B ^{4 +} _1-x C ³⁺ _x O _3- δ
The perovskite type oxide represented by (0 <X ≦ 0.5 and 0 <δ <0.5) is an ordinary solid phase method, that is, an oxide or carbonate or nitrate of each metal component as a raw material. It is synthesized by mixing salts such as the above at a target composition ratio and firing, but it may be synthesized by a wet method or a vapor phase method other than the above.

At present, for example, available ZrO ₂ inevitably contains about 0.9 to 2.0 mol% of HfO ₂ , and ZrO ₂ is weighed in the state of containing HfO _2. However, the properties of the finally prepared photocatalyst are not deteriorated.

Next, after mixing the above starting material powders,
This mixture is dried at 100 to 140 ° C. in a constant temperature bath, and then 10 to 5 at 1350 to 1450 ° C. in an oxygen-containing gas such as air.
It is calcined for 0 hours. After calcination, re-pulverize with a mortar etc. and mix with a planetary rotary mill etc.

After that, it is molded into a disc shape at a pressure of 200 to 300 MPa, and is heated in an oxygen-containing gas such as air at 1450 to
By firing at 1650 ° C. for 50 to 60 hours, the perovskite type oxide represented by the above general formula is obtained.

Further, the shape of the photocatalyst according to the present invention comprising a perovskite type oxide is preferably particles having a large surface area in order to effectively utilize light, and generally the particle size is 0.1 to 10 μm, preferably 0.1 to 1 μm is suitable. As a conventional means for obtaining such a particle size, the calcined sample is, for example, manually ground using a mortar, or ground using a ball mill, a planetary rotary ball mill, etc. A sample powder of is obtained.

The obtained photocatalyst having a catalytic activity in the visible light region and the combination of polyorganosiloxane and an acrylic polymer have the functions of both polymers of film strength (film forming property), weather resistance and water repellency. A silicone acrylic emulsion paint is dispersed in an aqueous solvent (preferably containing water as a main component) to form a paint, and if this paint is applied and cured at room temperature, the adhesiveness is good, and the antibacterial properties are excellent in stain prevention and antibacterial properties. A photocatalytic coating composition and an antibacterial photocatalytic member can be obtained.

Silicone acrylic emulsion paints include a general emulsion-polymerized emulsion having a milky white appearance having a particle size of 80 to 500 nm and a colloidal dispersion having a semitransparent blue-white appearance having a particle size of 8 to 80 nm.

In the case of a two-component water-based coating composition containing a curing agent, it is preferable to add the curing agent immediately before use. The curing temperature of the composition is 0 ° C to 150 ° C, preferably 1 ° C.
0 ° C to 80 ° C is preferable.

It is also possible to add an antibacterial metal to the photocatalytic substance. Here, as the antibacterial metal, copper,
It is at least one selected from silver, iron, zinc, platinum, gold, palladium, cadmium, cobalt, rhodium, and ruthenium. It is considered that by supporting an antibacterial metal on the photocatalytic substance, charge separation is promoted, the activity of the photocatalyst is improved, and the antibacterial property and antifungal property are improved.

Further, copper acetate or the like may be added to the copper-supported photocatalyst sol, and if necessary, ultraviolet irradiation may be performed to perform photoreduction plating. At this time, if the amount of the metal supported on the photocatalyst solid content is 5 wt% or more, the surface of the photocatalyst particles is covered with the metal and the oxidation points are lost, so that the redox performance of the photocatalyst is deteriorated. Therefore, when copper is carried by photoreduction plating, it is optimal to improve the antibacterial property and the antifungal property by setting the amount of the metal carried in the range of 1 wt% to 5 wt% with respect to the photocatalyst. However, there is no particular limitation when copper or copper oxide is mixed and added.

The photocatalyst and the silicone acrylic emulsion paint are dispersed in an aqueous solvent (preferably containing water as a main component) to prepare a paint, and the surface of an inorganic material such as glass,
Metal surface such as stainless steel, PET, ABS, FRP
(Glass fiber reinforced plastic) Hot water resistance and alkali resistance by applying or spraying to the surface of a base material such as a molded article so as to have a thickness of 0.1 to 200 μm and then curing at room temperature at 10 ° C. to 80 ° C. A photocatalytic film having excellent antibacterial and antifungal properties with good adhesion and weather resistance is formed.

In order to exert sufficient antibacterial and antifungal properties by the photocatalyst, it is necessary to add the photocatalyst in an amount of 5 wt% or more based on the solid content. The content of photocatalyst is 8 with respect to the solid content.
When it is added in an amount of 0 wt% or more, the adhesion of the coating, the hot water resistance, the alkali resistance and the weather resistance are lowered because the proportion of the water-based paint is small. Therefore, the amount of photocatalyst added to the silicone acrylic emulsion paint is from 5 wt% to 80 w
t% is desirable.

As the coating method of the antibacterial photocatalyst coating, various coating methods such as brush coating, spraying, dipping, flow coating and bar coating can be adopted.

The base material to which the present invention is applicable is a bath,
Bathroom wall material, bathroom floor material, bathroom grating, bathroom ceiling, shower hook, bathtub handgrip, bathtub apron, bathtub drain plug, bathroom window, bathroom window frame, bathroom window floorboard, bathroom lighting fixture. , Drain pan, drain pit, bathroom door,
Bathroom door frame, bathroom window bar, bathroom door bar, slats, mats,
Soap holders, tubs, bathroom mirrors, bath chairs, transfer boards, water heaters, bathroom storage shelves, bathroom handrails, bath lids, bathroom towel racks, shower chairs, bathroom parts such as washbasin holders, etc., Kitchen back for kitchen, kitchen flooring, sink, kitchen counter, drain basket, dish dryer, dish washer, stove, range hood, ventilation fan, stove ignition part, kitchen parts such as knob of stove, urinal, large Toilet bowl, toilet trap, toilet pipe, toilet flooring, toilet wall, toilet ceiling, ball tap, water stopcock, paper wrapper, toilet seat, lifting toilet seat, toilet door, toilet booth key, toilet towel Rests, toilet lids, handrails for toilets, counters for toilets, flush valves, tanks, toilet parts such as spouting nozzles for toilet seats with a cleaning function, wash bowls, wash traps, washrooms Mirrors, wash shelves, drain plugs, toothbrush stands, light fixtures for wash mirrors, wash basins, water soap dispensers, wash basins, mouth washer, hand dryers, wash basins such as rotating towels, washing tubs, washing Machine lids, washing machine pans, dehydration tanks, air conditioner filters, touch panels, faucet fittings, human body detection sensor covers, shower hoses, shower spouts, sealants, joints, etc.

[0031]

EXAMPLES Photocatalyst Sr (Ce _0.95 Y _0.05 ) O _{3-of the} present invention
δ was prepared by the following method. (Raw material) SrCO ₃ powder (Kojundo Chemical Laboratory Co., Ltd.)
Made, purity 99.9%, ig.-loss 0.04%): 5.5
906 g CeO ₂ powder (manufactured by Santoku Metal Industry Co., Ltd., purity 99.99)
%, Ig.-loss 3.75%): 6.4057 g, Y ₂ O ₃ powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.9)
%, Ig.-loss 2.19%): 0.2189 g (mixing) 1) Each sample after weighing was added with ethanol using a zirconia mortar and mixed for 1.5 hours.

2) The mixed sample was dried, put in a zirconia pot, and ground for 40 minutes using a planetary rotary ball mill. (Drying) The mixed sample was dried in a constant temperature bath at 120 ° C for 30 minutes or more. (Calcination) The dried sample was put into a rhodium / platinum crucible and calcined at 1400 ° C for 10 hours in the atmosphere. (Re-grinding / mixing / drying) After calcination, the powder was re-ground in a mortar and mixed in a planetary rotary mill. Then, it was dried under the same conditions as the previous drying. (Molding) A disk having a diameter of 17 mm was molded at a pressure of 265 MPa. (Firing) Firing was performed in the air at 1500 ° C. for 50 hours. (Pulverization) After firing, the powder was pulverized in a mortar for 1 hour to obtain a sample powder. (Hydrogen dissolution) Hydrogen was dissolved as ions in the fired product thus prepared. The composition is Sr (Ce _0.95
Y _0.05 ) O _3- δ.

Room temperature curing type water-based silicone acrylic emulsion paint (Kaneka, W # 0141, two-component acrylic silicone emulsion base agent, solid content concentration 50 wt%,
pH 7-8, average particle size 215 nm) 10 g and the above photocatalyst slurry (concentration 10 of photocatalyst prepared by the above method)
(wt%) 50 g was stirred for 1 minute to obtain a paint. A floor pan sample (20 cm square) of SRP (Sheet molding compound, unsaturated polyester resin, filler, sheet-shaped molding material made of glass fiber) which is a FRP molding material is washed with water,
After degreasing with isopropanol, the photocatalyst paint was applied.
After coating for 1 hour at room temperature (room temperature 28 ° C.), it was cured at room temperature to obtain an antibacterial photocatalytic coating film having a photocatalyst concentration of 50 wt% based on the solid content. A cross-cut peeling test was conducted on the coating film, but it was 100/100 and no peeling was observed. No peeling of the coating was observed when rubbed with a dry Kimwipe. No change in appearance was observed even after leaving 1% NaOH dropwise for 24 hours. No change in appearance was observed even after immersion in 60 ° C. hot water for 24 hours.

[0034]

Comparative Example Titanium oxide photocatalyst secondary processed product (photocatalyst manufactured by Ishihara Sangyo, ST-K03, inorganic coating agent, solid content concentration 10% (normal dry type), titania / silicate ratio 50/5
0, main application: antibacterial, antifouling FRP molding material SMC (Sh
A floor pan sample (20 cm square) of an eet molding compound, a sheet-shaped molding material composed of an unsaturated polyester resin, a filler, and a glass fiber was washed with water and degreased with isopropanol, and then the above copper-supported photocatalytic paint was applied. It is 0/100 when cross-cut peeling test is performed after heating and drying at 150 ° C for 30 minutes.
Completely peeled off. Also, the film was dissolved after 1% NaOH was dropped and left for 1 hour. Also, after being immersed in warm water at 60 ° C. for 24 hours, the film below the water line was completely peeled off.

In addition, the above spectrophotometer (U, manufactured by Hitachi Ltd.)
(4000 spectrophotometer), the light absorption spectrum of the coating film was measured by the diffuse reflection method, and the state of light absorption in the visible light region of the sample was examined. Since the diffuse reflectance of the photocatalyst according to the example with respect to visible light having a wavelength λ> 420 nm is lower than the diffuse reflectance of the photocatalyst according to the comparative example, light absorption in the visible light region of the photocatalyst according to the example is shown. Was confirmed to be superior to the photocatalyst according to the comparative example.

[0036]

INDUSTRIAL APPLICABILITY The antibacterial photocatalyst paint and coating film of the present invention are excellent photocatalysts that use an inexpensive photocatalyst of perovskite type oxide that exhibits photocatalytic activity based on a simple new mechanism in the visible light region. It has high performance, is environment-friendly because it does not contain a solvent, and is easy to work even during construction.By using a silicone acrylic emulsion paint that is a composite of polyorganosiloxane and acrylic polymer, film strength (film formation) Properties), weather resistance, and water repellency. Therefore, the coating film formed by applying the antibacterial photocatalyst coating is excellent in hot water resistance and alkali resistance.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01J 35/02 ZAB B01J 35/02 ZABJ C09D 5/02 C09D 5/02 5/14 5/14 183/04 183/04 (72) Inventor Takahisa Omata 2-1 Yamadaoka, Suita City, Osaka Prefecture F-term in Graduate School of Engineering, Osaka University (reference) 4G069 AA02 AA03 BA48A BB02A BB02B BB06A BB06B BC08A BC09A BC12A BC12B BC13A BC15A BC17A BC18A BC20A BC32A BC33A BC35A BC36A BC38A BC40A BC40B BC41A BC43A BC43B BC49A BC51A BC66A BC67A BC70A BC71A BC72A BC75A CA01 CA05 CA11 CD10 DA03 EA01 EA01Y EA07 EC23 MA05 CG23 HA02 DH23 CG18H021

Claims (6)

[Claims] 1. An antibacterial photocatalyst paint containing a silicone acrylic emulsion paint, an aqueous solvent and a photocatalyst, wherein the photocatalyst is capable of dissolving and retaining hydrogen as hydrogen ions through the holes formed by doping the acceptor. A perovskite-type oxide which can be obtained by the general formula (I): A ²⁺ B ^{4 +} _1-x C ³⁺ _x O ₃ -δ (0 <X ≦ 0.5,
Further, it is a perovskite type oxide represented by 0 <δ <0.5) and doped with a cation C having a lower valence than B ions to 50 mol%, and A is selected from alkaline earth metal elements. 1 or more elements, B is a lanthanoid, and a selected element selected from IVa and IVb elements
More than one element, C is a lanthanoid, and IIIa, I
An antibacterial photocatalyst coating, which is a photocatalyst that is one or more elements selected from the IIb group elements. 2. The antibacterial photocatalyst paint according to claim 1, wherein the silicone-acrylic emulsion paint containing the photocatalyst is a composite of polyorganosiloxane and acrylic polymer. 3. The antibacterial photocatalyst paint according to claim 1, wherein the paint containing the photocatalyst is a room temperature cross-linking type paint. 4. The photocatalyst is a perovskite type oxide of the general formula (I), wherein A is Ca, Sr, B.
2. The antibacterial photocatalyst coating composition according to claim 1, wherein the antibacterial photocatalyst paint is a, B is Zr and Ce, and C ions doped into the B site are Y, Ga and In ions. 5. The antibacterial photocatalyst coating composition according to claim 1, wherein the photocatalyst carries an antibacterial metal. 6. An antibacterial photocatalytic member, characterized in that the antibacterial photocatalytic coating composition according to any one of claims 1 to 5 is applied to a substrate and cured to form an antibacterial photocatalytic film.