JP3743075B2 - Antifogging dental mirror and antifogging method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antifogging dental mirror and an antifogging method for a dental mirror.
[0002]
[Prior art]
Dental mirrors for observing the oral cavity often become cloudy due to patient breathing, which can interfere with accurate diagnosis.
In general, fogging occurs on the surface of an article because moisture in the atmosphere condenses and condenses on the surface when the surface is placed at a temperature below the dew point of the atmosphere.
If the condensed water droplets are sufficiently fine and their diameter is about half of the wavelength of visible light, the water droplets scatter light and the dental mirror will appear opaque and lose visibility.
If condensation of moisture proceeds further and fine condensed water droplets fuse together and grow into larger discrete water droplets, the surface swells due to the refraction of light at the water droplet / surface interface and the water droplet / air interface, Blurry, mottled, or cloudy, loss of visibility.
As used herein, the term “anti-fogging” broadly means a technique for preventing such haze, growth of condensed water droplets, and optical failure due to adhesion of water droplets.
[0003]
As is well known, a conventionally used antifogging method is to apply an antifogging composition containing a hydrophilic compound such as polyethylene glycol or a water repellent compound such as silicone to the surface. However, this type of anti-fogging film is only temporary, and is easily removed by washing and contact, and has a drawback that it loses its effect at an early stage.
[0004]
Problems to be Solved by the Invention
An object of the present invention is to provide a dental mirror capable of realizing a high degree of visibility and an anti-fogging method thereof.
Another object of the present invention is to provide a dental mirror capable of maintaining a high degree of hydrophilicity over a long period of time and exhibiting an antifogging property and an antifogging method thereof.
Another object of the present invention is to provide a dental mirror capable of maintaining a high degree of hydrophilicity almost permanently and exhibiting antifogging properties, and a method for antifogging the same.
[0005]
[Means for Solving the Problems]
The present invention is based on the discovery that in a member in which a surface layer containing a photocatalyst is formed, when the photocatalyst is photoexcited, the surface of the member is highly hydrophilized.
This phenomenon is considered to proceed by the mechanism shown below. That is, when the photocatalyst is irradiated with light having energy greater than the energy gap between the upper end of the valence band and the lower end of the conduction band of the photocatalyst, electrons in the valence band of the photocatalyst are excited to generate conduction electrons and holes. By the action of either or both of them, polarity is probably imparted to the surface, and polar components such as water and hydroxyl groups are collected. Then, by a cooperative action of either or both of conduction electrons and holes and the polar component, the chemical bond between the surface and the contaminant chemically adsorbed on the surface is cut, and the chemically adsorbed water on the surface. Is adsorbed, and a physical adsorption water layer is formed thereon.
Further, once the surface of the member is highly hydrophilized, the hydrophilicity of the surface lasts for a certain period of time even if the member is held in a dark place.
[0006]
The present invention provides an antifogging dental mirror having a surface layer containing a substantially transparent photocatalyst on the surface of a dental mirror substrate.
By providing a surface layer containing a photocatalyst, the surface of the surface layer exhibits hydrophilicity in response to photoexcitation of the photocatalyst, and condensed water and / or water droplets adhering to the layer spread uniformly over the surface of the layer, Clouding or dripping is prevented by moisture condensed water and / or water droplets.
[0007]
In a preferred embodiment of the present invention, the surface layer further contains silica.
By containing silica, the surface tends to exhibit a high degree of hydrophilicity close to a water wetting angle of 0 °, and the hydrophilicity retention when held in a dark place is improved. The reason seems to be related to the fact that silica can store water in its structure.
[0008]
In a preferred embodiment of the present invention, the surface layer further contains a solid superacid.
By containing a super strong acid, the surface tends to exhibit a high degree of hydrophilicity close to a water wetting angle of 0 °, and the hydrophilicity retention when kept in a dark place is improved. The reason is that when a super strong acid is contained in the surface layer, the surface polarity is extremely large regardless of the presence or absence of light. Therefore, water molecules that are polar molecules are selectively adsorbed rather than hydrophobic molecules. Easy to make. Therefore, a stable physical adsorption water layer is easily formed, and even when kept in a dark place, the hydrophilicity of the surface can be maintained at a high level for a considerably long time.
[0009]
In a preferred embodiment of the present invention, the surface layer further contains silicone.
By containing silicone, at least a part of the organic group bonded to the silicon atom in the silicone is substituted with a hydroxyl group by photoexcitation of the photocatalyst, and a physical adsorption water layer is formed thereon, whereby the surface is It exhibits a high degree of hydrophilicity close to a water wetting angle of 0 °, and improves hydrophilicity retention when held in a dark place.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, a specific configuration of the present invention will be described.
As shown in FIG. 1 or 2, a layer containing a photocatalyst is formed on the surface of the base material on the surface of the antifogging dental mirror in the present invention.
By taking such a surface structure, the surface of the dental mirror is highly hydrophilized in response to photoexcitation of the photocatalyst. As a result, even if moisture in the atmosphere condenses and adheres, it does not grow in the form of water droplets, but forms a uniform water film, and is prevented from being clouded or fogged by moisture condensed water and / or water droplets. The
[0011]
In FIG. 1, when a surface layer consists only of a photocatalyst, it is preferable that a photocatalyst is an oxide. By doing so, the oxide exhibits hydrophilicity in a state where the environmental pollutants are not adsorbed. Therefore, it is easy to exhibit hydrophilicity by eliminating the pollutants by photoexcitation and forming an adsorbed water layer. A uniform water film can be formed. In FIG. 2, M represents a metal element. Therefore, in the case of FIG. 2, the outermost surface is made of a general inorganic oxide. In this case as well, since the oxide is hydrophilic in the state in which no environmental pollutants are adsorbed, the pollutants are eliminated by the photoexcitation action of photocatalytic titanium oxide mixed in the surface layer in addition to the inorganic oxide. A uniform water film can be formed by forming an adsorbed water layer.
[0012]
The dental mirror substrate in the present invention includes a mirror made of a glass substrate with a reflective coating on the back surface, a mirror made of a transparent plastic substrate with a reflective coating on the back surface, a substrate surface made of plastic, glass, metal, etc. The surface is made of a transparent body, such as a mirror provided with a reflective coat and a transparent hard coat provided thereon, and a mirror provided with a transparent hard coat on a transparent plastic substrate provided with a reflective coat on the back. A mirror can be suitably used.
[0013]
A photocatalyst is an excitation (photoexcitation) of electrons in the valence band when it is irradiated with light (excitation light) with an energy (ie short wavelength) larger than the energy gap between the conduction band and the valence band of the crystal. ) Is generated and can generate conduction electrons and holes, such as anatase titanium oxide, rutile titanium oxide, tin oxide, zinc oxide, dibismuth trioxide, tungsten trioxide, ferric oxide, Strontium titanate or the like can be suitably used. Here, as a light source used for photoexcitation of the photocatalyst, a storage container dedicated to the dental mirror of the present invention is provided in addition to a lamp for peeping into the oral cavity and sunlight, and a light source capable of irradiating excitation light is installed there. Good. In this case, for example, an incandescent lamp, a metal halide lamp, a mercury lamp, a xenon lamp, or a germicidal lamp can be suitably used as the light source to be used. By photoexcitation of the photocatalyst, because the substrate surface is highly hydrophilized, illuminance of the excitation light, may if 0.001 mW / cm ² or more, preferably that it 0.01 mW / cm ² or more, 0. More preferably, it is 1 mW / cm ² or more.
[0014]
The film thickness of the surface layer containing the photocatalyst is preferably 0.4 μm or less. By doing so, white turbidity due to irregular reflection of light can be prevented, and the surface layer becomes substantially transparent.
Furthermore, it is more preferable that the film thickness of the surface layer containing the photocatalyst is 0.2 μm or less. By doing so, coloration of the surface layer due to light interference can be prevented.
Further, the thinner the surface layer, the higher the transparency. Furthermore, if the film thickness is reduced, the wear resistance of the surface layer is improved.
Further, a wear-resistant or corrosion-resistant protective layer that can be hydrophilized or another functional film may be provided on the surface of the surface layer.
[0015]
The surface layer preferably has a refractive index that is not so high as compared with the base material. Preferably, the refractive index of the surface layer is 2 or less. If it does so, the reflection of the light in the interface of a base material and a surface layer and the interface of a surface layer and air can be suppressed. In order to make the refractive index of the surface layer 2 or less, a substance having a refractive index of 2 or less is used for the photocatalyst, or when the photocatalyst has a refractive index of 2 or more, another substance having a refractive index of 2 or less is used as the surface layer. Add to.
As a photocatalyst having a refractive index of 2 or less, tin oxide (refractive index 1.9) or the like can be used.
Photocatalysts having a refractive index of 2 or more include anatase-type titanium oxide (refractive index 2.5) and rutile-type titanium oxide (refractive index 2.7). In this case, other substances having a refractive index of 2 or lower For example, calcium carbonate (refractive index 1.6), calcium hydroxide (refractive index 1.6), magnesium carbonate (refractive index 1.5), strontium carbonate (refractive index 1.5), dolomite (refractive index 1. 7), calcium fluoride (refractive index 1.4), magnesium fluoride (refractive index 1.4), silica (refractive index 1.5), alumina (refractive index 1.6), silica sand (refractive index 1. 6), montmorillonite (refractive index 1.5), kaolin (refractive index 1.6), sericite (refractive index 1.6), zeolite (refractive index 1.5), tin oxide (refractive index 1.9), etc. May be added to the surface layer.
[0016]
A metal such as Ag, Cu, or Zn can be added to the surface layer. The surface layer to which the metal is added can kill bacteria and sputum attached to the surface even in the dark.
[0017]
A platinum group metal such as pt, Pd, Ru, Rh, Ir, and Os can be added to the surface layer. The surface layer to which the metal is added can enhance the redox activity of the photocatalyst and improve the deodorizing and purifying action.
In addition, when a solid acid is added in addition to the photocatalyst, the acidity of the solid acid is improved by the addition of the platinum group metal, so that the hydrophilicity is also improved and the formation of a water film of the adhering water is further promoted. Hydrophilic maintenance property when the photocatalyst is not irradiated with excitation light for a long period of time is also improved.
Mo can be added to the surface layer. When a solid acid is added in addition to the photocatalyst, the addition of Mo improves the acidity of the solid acid, thereby improving the hydrophilicity and promoting the formation of a water film of the adhering water. The hydrophilic maintenance property when not irradiated with light is also improved.
[0018]
In the case where the substrate is a glass containing alkali network modifying ions such as sodium (soda lime glass, parallel plate glass, etc.), an intermediate layer such as silica may be formed between the substrate and the surface layer. If it does so, it will prevent that an alkali network modification ion diffuses from a base material to a surface layer during baking, and a photocatalytic function will be exhibited better.
[0019]
“Hydrophilic” means a property that is easily adapted when water is dropped on the surface, and generally refers to a state in which the water wetting angle is less than 90 °. The high hydrophilicity in the present invention refers to a property that is very familiar when water is dropped on the surface, and more specifically, refers to a state where the water wetting angle is about 10 ° or less.
In particular, as disclosed in PCT / JP96 / 00734, the antifogging property has a water wetting angle of preferably 10 ° or less, and more preferably 5 ° or less.
[0020]
The solid acid in the present invention includes sulfuric acid-supported Al ₂ O ₃ , sulfuric acid-supported TiO ₂ , sulfuric acid-supported ZrO ₂ , sulfuric acid-supported SnO ₂ , sulfuric acid-supported Fe ₂ O ₃ , sulfuric acid-supported SiO ₂ , sulfuric acid-supported HfO ₂ , TiO ₂ / WO ₃ , wO ₃ / SnO ₂ , WO ₃ / ZrO ₂ , WO ₃ / Fe ₂ O ₃ , SiO ₂ · Al ₂ O ₃ , TiO ₂ / SiO ₂ , TiO ₂ / Al ₂ O ₃ , TiO ₂ / ZrO ₂ Etc. can be suitably used.
[0021]
Next, a method for forming the surface layer will be described.
First, the production method in the case where the surface layer is composed only of the photocatalyst will be described by taking the case where the photocatalyst is anatase type titanium oxide as an example. There are roughly three methods in this case. One method is a sol coating baking method, the other method is an organic titanate method, and the other method is an electron beam evaporation method.
(1) Sol coating and baking method Anatase-type titanium oxide sol is applied to the surface of a substrate by a method such as spray coating, dip coating, flow coating, spin coating, or roll coating, and baked.
(2) Addition of hydrolysis inhibitors (hydrochloric acid, ethylamine, etc.) to organic titanates such as organic titanate titanium alkoxides (tetraethoxytitanium, tetramethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, etc.), titanium acetate, titanium chelate, etc. , After diluting with a non-aqueous solvent such as alcohol (ethanol, propanol, butanol, etc.), after partially or fully advancing hydrolysis, the mixture is spray coated, dip coated, It is applied and dried by a method such as a flow coating method, a spin coating method, or a roll coating method. By drying, hydrolysis of the organic titanate is completed to produce titanium hydroxide, and an amorphous titanium oxide layer is formed on the substrate surface by dehydration condensation polymerization of titanium hydroxide. Thereafter, firing is performed at a temperature equal to or higher than the crystallization temperature of anatase, and amorphous titanium oxide is phase-transformed into anatase-type titanium oxide.
(3) Electron Beam Evaporation Method An amorphous titanium oxide layer is formed on the surface of the substrate by irradiating a titanium oxide target with an electron beam. Thereafter, firing is performed at a temperature equal to or higher than the crystallization temperature of anatase, and amorphous titanium oxide is phase-transformed into anatase-type titanium oxide.
[0022]
Next, the case where the surface layer is made of a photocatalyst and silica will be described by taking the case where the photocatalyst is anatase type titanium oxide as an example. There are, for example, the following three methods in this case. One method is a sol coating baking method, the other method is an organic titanate method, and the other method is a tetrafunctional silane method.
(1) Sol coating and baking method A mixed liquid of anatase-type titanium oxide sol and silica sol is applied to the surface of the substrate by spray coating, dip coating, flow coating, spin coating, roll coating, or the like, followed by baking. To do.
(2) Organic titanate method Titanium alkoxide (tetraethoxy titanium, tetramethoxy titanium, tetrapropoxy titanium, tetrabutoxy titanium, etc.), titanium acetate, titanium chelate and other organic titanates with hydrolysis inhibitors (hydrochloric acid, ethylamine, etc.) and silica sol After adding and diluting with non-aqueous solvent such as alcohol (ethanol, propanol, butanol, etc.), after partially or fully hydrolyzing the mixture, the mixture is spray coated, dip coated It is applied by a method such as a method, a flow coating method, a spin coating method, or a roll coating method, and dried. By drying, hydrolysis of the organic titanate is completed to produce titanium hydroxide, and an amorphous titanium oxide layer is formed on the substrate surface by dehydration condensation polymerization of titanium hydroxide. Thereafter, firing is performed at a temperature equal to or higher than the crystallization temperature of anatase, and amorphous titanium oxide is phase-transformed into anatase-type titanium oxide.
(3) A tetrafunctional silane method Tetraalkoxysilane (tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetramethoxysilane, etc.) and a mixture of anatase-type titanium oxide sol are spray coated and dip coated on the surface of the substrate. After applying by a method such as a flow coating method, a spin coating method or a roll coating method, and hydrolyzing as necessary to form silanol, the silanol is subjected to dehydration condensation polymerization by a method such as heating.
[0023]
Next, the case where the surface layer is composed of a photocatalyst and a solid acid will be described by taking as an example the case where the photocatalyst is anatase-type titanium oxide and the solid acid is TiO ₂ / WO ₃ . In this case, the ammonia solution of tungstic acid and anatase-type titanium oxide sol are mixed, and if necessary, the mixture diluted with a diluent (water, ethanol, etc.) is spray coated or dip coated onto the surface of the substrate. It is applied by a method such as a method, a flow coating method, a spin coating method or a roll coating method, and baked.
[0024]
Next, the case where the surface layer is made of a photocatalyst and silicone will be described taking the case where the photocatalyst is anatase-type titanium oxide as an example. In this case, the coating is made of uncured or partially cured silicone or a silicone precursor and anatase-type titanium oxide sol, and the silicone precursor is hydrolyzed as necessary, and then the mixture is mixed. Is applied to the surface of the substrate by spray coating, dip coating, flow coating, spin coating, roll coating, etc., and the silicone precursor hydrolyzate is subjected to dehydration condensation polymerization by methods such as heating. In addition, a surface layer composed of anatase-type titanium oxide particles and silicone is formed. In the formed surface layer, the anatase-type titanium oxide is photoexcited by irradiation with light containing ultraviolet rays, whereby at least a part of the organic group bonded to the silicon atom in the silicone molecule is replaced with a hydroxyl group, and further thereon A physisorbed water layer is formed and exhibits a high degree of hydrophilicity.
Here, the precursors of silicone include methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltributoxysilane, ethyltripropoxysilane, phenyl Trimethoxysilane, phenyltriethoxysilane, phenyltributoxysilane, phenyltripropoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, dimethyldipropoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldibutoxy Silane, diethyldipropoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylmethyldibutoxysilane, Methylpropenylmethyl dipropoxy silane, .gamma.-glycidoxypropyltrimethoxysilane, and hydrolysates thereof, mixtures thereof can be suitably used.
[0025]
【Example】
Tetraethoxysilane (Wako Pure Chemical Industries) 0.69g, anatase-type titanium oxide sol (Nissan Chemical, TA-15, average particle size 10nm) 1.07g, ethanol 29.88g, and pure water 0.36g are mixed, and coating solution Was prepared. This coating solution was applied on a 10 cm square glass mirror substrate (a substrate having a reflective coating layer and a resin layer formed on the back surface of a plate glass) by a flow coating method. By holding this glass plate at a temperature of about 150 ° C. for about 20 minutes, a coating in which tetraethoxysilane is subjected to hydrolysis and dehydration condensation polymerization and anatase-type titanium oxide particles are bound with amorphous silica is applied to the glass plate. Formed on the surface. The weight ratio of titanium oxide to silica in this coating was 1.
After leaving this glass plate in a dark place for several days, UV light is applied to the surface of the sample with an ultraviolet light source (Sankyo Electric, Black Light Blue (BLB) fluorescent lamp) at an ultraviolet illuminance of 0.5 mW / cm ² for about 1 hour. Irradiation gave # 1 sample. For comparison, a # 2 sample was also prepared in which a 10 cm square glass plate was left in the dark for several days.
First, water droplets were dropped on the # 1 sample and the # 2 sample, the state after the dropping was observed, and the contact angle with water was measured. Here, the contact angle with water was evaluated by using a contact angle measuring device (Kyowa Interface Science, CA-X150) as the contact angle with water 30 seconds after dropping.
As a result, when water droplets were dropped from the microsyringe onto the sample surface, it was observed that the water droplets uniformly spread in the form of a water film. The contact angle with water after 30 seconds was highly hydrophilized to about 0 °.
On the other hand, in the # 2 sample, when a water droplet was dropped from the microsyringe onto the sample surface, the water droplet became familiar with the surface, but did not reach a uniform water film shape. The contact angle with water after 30 seconds was 30 °.
Next, the # 1 sample and the # 2 sample were blown to check for the occurrence of fogging.
As a result, clouding occurred in the # 2 sample, whereas no fogging occurred in the # 1 sample.
Further, the # 1 sample was left in the dark for 2 days to obtain a # 3 sample. And about # 3 sample, the contact angle with water was similarly measured with the contact angle measuring device.
As a result, when water droplets were dropped onto the sample surface from the microsyringe on the # 3 sample, it was observed that the water droplets uniformly spread in the form of a water film as in the case of the # 1 sample. The contact angle with water was maintained at about 3 °.
Next, the # 3 sample was observed for the occurrence of fogging after blowing.
As a result, no cloudiness was observed.
[0026]
【The invention's effect】
In the present invention, by providing a surface layer containing substantially transparent photocatalytic titanium oxide particles on the surface of the dental mirror, the surface of the surface layer exhibits hydrophilicity in accordance with photoexcitation of the photocatalyst, and the attached moisture content. The condensed water and / or water droplets spread evenly on the surface of the layer, so that the moisture condensed water and / or water droplets are prevented from being clouded or fogged.
[Brief description of the drawings]
FIG. 1 is a view showing the surface structure of an antifogging dental mirror according to the present invention.
FIG. 2 is a view showing another surface structure of the anti-fogging dental mirror according to the present invention.

Claims (9)

Provided with a surface layer containing substantially transparent photocatalyst particles on the surface of the dental mirror substrate, and according to photoexcitation of the photocatalyst, the surface of the layer exhibits hydrophilicity and thus condensates moisture. Used after hydrophilization under irradiation with excitation light, in which water and / or water droplets spread uniformly over the surface of the layer and are prevented from being clouded or smeared by moisture condensed water and / or water droplets Anti-fogging dental mirror.  The antifogging dental mirror according to claim 1, wherein the surface layer further contains silica.  The antifogging dental mirror according to claim 1, wherein the surface layer further contains a solid acid.  The antifogging dental mirror according to claim 1, wherein the surface layer further contains silicone.  The antifogging dental mirror according to claim 1, wherein the surface of the surface layer exhibits a hydrophilicity of 10 ° or less in terms of a contact angle with water according to photoexcitation of the photocatalyst. . The film thickness of the said surface layer is 0.4 micrometer or less, The anti-fogging dental mirror of Claims 1-5 characterized by the above-mentioned. The film thickness of the said surface layer is 0.2 micrometer or less, The anti-fogging dental mirror of Claims 1-5 characterized by the above-mentioned. Antifogging dental mirror according to claim 1 to 5, wherein the refractive index of said surface layer is 2 or less. Preparing a dental mirror of claim 1-8, by photoexcitation of the photocatalyst contained in the surface layer of the dental mirror, without the surface of said layer hydrophilic, moisture adhering I following partial condensate and / or the step of water droplets to spread uniformly on the surface of the layer, antifogging method of dental mirror made of.

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