JP3744061B2 - Permeable pavement material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water-permeable pavement material made of porous ceramic. More specifically, the present invention relates to a water-permeable pavement material in which dirt is difficult to adhere and pores are self-purified by rainfall.
[0002]
[Prior art]
Water-permeable pavement materials made of porous ceramics are used for pavement where rainwater is exposed, such as sidewalks, verandas, porches, and poolsides, and rainwater is soaked into the ground to improve drainage. , Preventing slipping or freezing.
For example, as disclosed in JP-A-60-171972, JP-A-63-260876, and JP-A-64-42372, this type of water-permeable pavement material includes anti-fluorite, blast furnace slag, and waste ceramic materials. Aggregate particles such as glass, frit, feldspar and the like are produced by binding, and minute continuous pores that allow permeation of rainwater are formed between the aggregate particles.
[0003]
[Problems to be solved by the invention]
Along with environmental pollution, dirt in permeable pavement materials has become prominent in urban areas. The pores of the water-permeable pavement are attached with lipophilic contaminants such as carbon black in urban dust, which not only detracts from the beauty of the pavement but also reduces the water permeability of the pavement due to clogging of the pores. .
The objective of this invention is providing the water-permeable pavement material which can maintain the outstanding water permeability over a long period of time.
[0004]
[Means for Solving the Problems]
The inventor has discovered that photoexcitation of the photocatalyst results in a highly hydrophilic surface of the photocatalyst.
The present invention is based on such discovery, and is characterized in that the inner peripheral surface of pores located in the vicinity of the surface of the water-permeable pavement is covered with a layer containing a semiconductor photocatalyst.
The pavement is irradiated with the sun during the daytime, and the photocatalyst located near the surface of the pavement is photoexcited by sunlight. With photoexcitation, the surface of the photocatalyst-containing layer is highly hydrophilized so that the contact angle with water is 10 ° or less, more specifically 5 ° or less, and particularly about 0 °. Once highly hydrophilized, the surface hydrophilicity persists even at night.
[0005]
Lipophilic contaminants such as carbon black in urban dust are less likely to adhere to such highly hydrophilic surfaces. In addition, the superhydrophilic surface easily absorbs moisture in the air and is not electrostatically charged, so that dust does not easily adhere.
In addition, paving materials are sometimes exposed to rainfall. Since the affinity of the superhydrophilic surface for water is greater than the affinity for lipophilic contaminants such as carbon black, dirt adhering to the inner surface of the pores can be easily released from the surface by rainwater, and Each time it is washed away by rainwater, the inner peripheral surface of the pores is self-cleaned (self-cleaning).
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a water-permeable pavement material 10 is made of a porous ceramic. The porous ceramic is made of an inorganic binder such as glass, frit, or feldspar, and aggregate particles 12 such as anti-fluorite, blast furnace slag, and ceramic waste. 14 is formed by binding. Minute continuous pores 16 are formed between the aggregate particles 12 to impart water permeability to the pavement 10.
[0007]
Referring to the enlarged view of FIG. 2, the inner peripheral surface of the pores 16 is coated with a layer 18 containing semiconductor photocatalyst particles. The thickness of the photocatalyst containing layer 18 should be about 0.1 μm or less.
[0008]
As the photocatalyst, titania (TiO ₂ ) is most preferable. Titania is harmless and chemically stable. Either anatase-type titania or rutile-type titania can be used.
It is considered that when photocatalytic titania is photoexcited by ultraviolet rays, water is chemically adsorbed on the surface in the form of hydroxyl groups (OH ⁻ ) by photocatalysis, and as a result, the surface becomes superhydrophilic. Other photocatalysts which can be used include metal oxides such as _{ZnO, SnO 2, SrTiO 3,} WO 3, Bi 2 O 3, Fe 2 O 3. Since these metal oxides, like titania, contain metal elements and oxygen on the surface, it is thought that surface hydroxyl groups (OH ⁻ ) should be adsorbed.
[0009]
In the first embodiment of the present invention, the photocatalyst-containing layer 18 is formed of silica-containing titania. The ratio of silica to the total of titania and silica can be 5 to 90 mol%, preferably 10 to 70 mol%, more preferably 10 to 50 mol%. Any one of the following methods can be employed to form the photocatalyst-containing layer 18 made of silica-containing titania.
(1) A suspension containing anatase-type or rutile-type titania particles and silica particles is applied by spray coating or dip coating to the surface of the pavement and the inner peripheral surface of the pores 16 in the vicinity of the surface. Bake at temperature.
[0010]
(2) Amorphous silica precursors (for example, tetraalkoxysilanes such as tetraethoxysilane, tetraisopropoxysilane, tetra n-propoxysilane, tetrabutoxysilane, tetramethoxysilane; silanols that are hydrolysates thereof; (Or polysiloxane with an average molecular weight of 3000 or less) and a crystalline titania sol are applied by spray coating or dip coating to the surface of the pavement and the inner peripheral surface of the pores near the surface, and if necessary, hydrolyzed to produce silanol. After the formation, the photocatalyst-containing layer in which titania is bound with amorphous silica is formed by heating at a temperature of about 100 ° C. or higher to subject the silanol to dehydration condensation polymerization. In particular, if dehydration condensation polymerization of silanol is carried out at a temperature of about 200 ° C. or higher, the degree of polymerization of silanol can be increased and the alkali resistance performance of the photocatalyst-containing layer can be improved.
[0011]
(3) Disperse silica particles in a solution of amorphous titania precursor (organic titanium compound such as titanium alkoxide, chelate or acetate, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ). By applying the resulting suspension to the surface of the pavement and the inner surface of the pores near the surface by spray coating or dip coating, and subjecting the titanium compound to hydrolysis and dehydration condensation polymerization at temperatures from room temperature to 200 ° C. Then, an amorphous titania thin film in which silica particles are dispersed is formed. Subsequently, the amorphous titania is changed into crystalline titania by heating the pavement to a temperature of about 700 ° C.
[0012]
(4) Amorphous silica precursor in a solution of amorphous titania precursor (organic titanium compound such as titanium alkoxide, chelate or acetate, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ). (E.g., tetraalkoxysilanes such as tetraethoxysilane, tetraisopropoxysilane, tetra n-propoxysilane, tetrabutoxysilane, tetramethoxysilane, etc .; hydrolyzed silanols thereof; or polysiloxanes having an average molecular weight of 3000 or less ) And then applied by spray coating or dip coating to the surface of the pavement and the inner peripheral surface of the pores near the surface. Subsequently, these precursors are subjected to hydrolysis and dehydration condensation polymerization to form a thin film made of a mixture of amorphous titania and amorphous silica. Subsequently, the amorphous titania is changed into crystalline titania by heating the pavement to a temperature of about 700 ° C.
[0013]
In another embodiment of the present invention, the photocatalyst-containing layer 18 can be formed by dispersing particles of photocatalyst such as anatase titania in a proportion of 50% by weight or less in silicone (organopolysiloxane). Therefore, it is possible to use a coating composition in which titania particles are dispersed in a film-forming element made of uncured or partially cured silicone or a precursor of silicone.
[0014]
Examples of coating film forming elements include methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltri-t-butoxysilane; ethyltrichlorosilane, ethyltribromosilane, ethyltrimethoxy Silane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltri-t-butoxysilane; n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltri Isopropoxysilane, n-propyltri-t-butoxysilane; n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane n-hexyltriisopropoxysilane, n-hexyltri-t-butoxysilane; n-decyltrichlorosilane, n-decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyltriisopropoxysilane N-decyltri-t-butoxysilane; n-octadecyltrichlorosilane, n-octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n-octadecyltri-t- Butoxysilane; phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltrit-butoxysilane; tetrac Silane, tetrabromosilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane; dimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane, dimethyldiethoxysilane; diphenyldichlorosilane, diphenyldibromo Silane, diphenyldimethoxysilane, diphenyldiethoxysilane; phenylmethyldichlorosilane, phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane; trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, tri Isopropoxyhydrosilane, tri-t-butoxyhydrosilane; vinyltrichlorosilane, vinyltribromosilane, Vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane; trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, tri Fluoropropyltriisopropoxysilane, trifluoropropyltri-t-butoxysilane; γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycyl Sidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri-t-butoxysilane; γ-methacryloxypropyl Tildimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacrylic Roxypropyltri-t-butoxysilane; γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltri-t-butoxysilane; γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropi Lutriethoxysilane, γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-butoxysilane; β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltri Ethoxysilanes; partial hydrolysates thereof; and mixtures thereof can be used.
[0015]
This coating composition is applied to the surface of the paving material and the inner peripheral surface of pores near the surface, and the silicone is cured at a temperature of about 100 ° C to 200 ° C. When a pavement such as a sidewalk is constructed using this pavement, the pavement is exposed to the sun during the daytime, and the photocatalyst located near the surface of the pavement is photoexcited by sunlight. Along with the photoexcitation, a silicone derivative in which an organic group bonded to a silicon atom of the silicone molecule is at least partially substituted with a hydroxyl group is formed on the surface of the photocatalyst-containing silicone layer 18 by the action of the photocatalyst. It is superhydrophilic to such an extent that the contact angle becomes about 0 °.
[0016]
Lipophilic contaminants such as carbon black in urban dust are less likely to adhere to the surface of the photocatalyst-containing layer 18 that has been highly hydrophilized. Further, the surface of the superhydrophilic photocatalyst-containing layer 18 absorbs moisture in the air and is not charged by static electricity, so that dust does not easily adhere electrostatically. Furthermore, since the contact angle of inorganic substances such as mud and soil with water is 20 ° to 50 °, the photocatalyst containing layer 18 that has been superhydrophilicized to such an extent that the contact angle with water becomes about 0 ° is included in the photocatalyst containing layer 18. Inorganic dust such as mud and soil is difficult to adhere.
The water affinity of the superhydrophilic surface is greater than the affinity for lipophilic contaminants such as carbon black, so when pavement is exposed to rain, the dirt attached to the inner surface of the pores is The inside of the pores is self-cleaned.
As a result, clogging of the pores is prevented, and the paving material maintains excellent water permeability for a long period of time.
[0017]
In yet another embodiment of the present invention, the pavement is formed by coating aggregate particles 12 with a photocatalyst containing layer 18 in advance, kneading with an inorganic binder such as glass, frit, feldspar, etc. It can be formed by firing at a temperature.
[0018]
【The invention's effect】
According to the present invention, dirt is prevented from adhering to the pores of the water-permeable pavement, and the dirt adhering to the inner peripheral surface of the pores is washed away by rain water every rain, and the pores are self-cleaned. The water permeability of the paving material can be maintained over a long period of time.
[Brief description of the drawings]
FIG. 1 is a schematic enlarged sectional view of a water-permeable pavement material of the present invention.
FIG. 2 is a cross-sectional view in which a part of the pavement shown in FIG. 1 is further enlarged.
[Explanation of symbols]
10: Water-permeable pavement material 16: Pore 18: Photocatalyst containing layer

Claims (4)

The inner peripheral surface of pores located in the vicinity of the surface of the porous water-permeable pavement is covered with a layer containing a semiconductor photocatalyst, and the surface of the photocatalyst-containing layer is in contact with water as the photocatalyst is photoexcited by sunlight. A self-cleaning water-permeable pavement characterized in that the contact angle is made hydrophilic to 10 ° or less, so that dirt adhered to pores is washed away by rainwater when the pavement is exposed to rain.   The water-permeable pavement material according to claim 1, wherein the photocatalyst-containing layer is formed of a silica layer in which photocatalyst particles are dispersed.   The photocatalyst-containing layer is formed of a silicone layer in which photocatalyst particles are dispersed, and the surface of the silicone layer is a silicone in which an organic group bonded to a silicon atom of a silicone molecule is at least partially substituted with a hydroxyl group by the action of the photocatalyst. The water-permeable pavement material based on Claim 1 currently formed with the derivative | guide_body.   The water-permeable pavement according to claim 2 or 3, wherein the photocatalyst is composed of titania.

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