KR100633767B1 - Hydrophilic member - Google Patents

Abstract

The hydrophilicity after washing is extremely short, and the hydrophilic member with high sustained effect of the recovered hydrophilicity is provided. A tin oxide (SnO ₂ ) film 2 is formed on the surface of the glass plate 1 as a substrate, and a silicon oxide (SiO ₂ ) film 3 as an overcoat layer on the surface of the tin oxide film (SnO ₂ ) 2. ). As the glass plate 1, it is made of soda glass containing SiO ₂ as a main component, and the tin oxide film (SnO ₂ ) 2 is formed by, for example, CVD, its thickness is 10 to 800 nm, and the surface average roughness of the surface. (Ra) is 0.5 to 25 nm. The silicon oxide (SiO ₂ ) film 3 is formed by sputtering and has a thickness of 0.1 to 100 nm. Then, silicon oxide (SiO ₂₎ film 3 is formed on a tin film (SnO _2), (2) the oxide, is as it is transferred irregularities of the tin oxide film (SnO ₂₎ (2), silicon oxide (SiO ₂ The surface average roughness Ra of the surface of the film 3 also becomes 0.5-25 nm.

Description

Hydrophilic member {Hydrophilic member}

The present invention relates to a hydrophilic member having excellent hydrophilicity, particularly hydrophilicity.

As prior art for providing anti-fogging properties by making a surface of a substrate such as glass hydrophilic, Japanese Patent Application Laid-Open Nos. 9-278431 and 9-295363, Japanese Patent Laid-Open No. 10-36144 and Japanese Patent Laid-Open No. 10-231146 are known.

Japanese Patent Laid-Open No. 9-278431 discloses a surface treatment agent comprising a phosphoric acid or a phosphate, a soluble aluminum compound, a water-soluble silicate, a surfactant, and a solvent on the surface of a substrate, and at the same time, the surface average roughness of the hydrophilic film. It is disclosed to make 0.5 to 500 nm.

Japanese Patent Laid-Open No. 9-295363 discloses that a titanium oxide film or a tin oxide film is formed on the surface of a substrate and the surface average roughness of the titanium oxide film or tin oxide film is set to 1 µm or more.

Japanese Patent Laid-Open No. 10-36144 discloses forming a photocatalyst film such as titanium oxide (TiO ₂ ) on the surface of a glass substrate, and forming a porous inorganic oxide film such as silicon oxide (SiO ₂ ) on the surface of the photocatalyst film. It is.

Japanese Patent Laid-Open No. 10-231146 discloses that an alkali barrier film and a photocatalyst film are formed on the surface of a glass substrate and the surface average roughness of the photocatalyst film is set to 1.5 to 80 nm.

In the technique described in Japanese Patent Laid-Open No. 9-278431, the chemical durability and wear resistance of the hydrophilic membrane is low and not practical. In the technique described in Japanese Patent Laid-Open No. 9-295363, the surface roughness (Ra) of the hydrophilic film is 1 µm or more, preferably 4 µm or more, so that the transparency is low (haze is high). It cannot be applied to the surface of the transparent substrate. Moreover, in the technique described in Japanese Patent Laid-Open No. 10-36144, since the hydrophilic membrane is a porous body, the wear resistance is low, and when dirt, such as fats and oils, enters the pores, the hydrophilic function is lost, and it is difficult to recover it. In addition, in the technique described in Japanese Patent Laid-Open No. 10-231146, it takes time to manufacture because the hydrophilic film is formed of a plurality of layers.

Moreover, all the above-mentioned prior art forms a hydrophilic film on the surface of a base material, and makes the surface a fine rough surface, and further improves hydrophilicity, or wash | cleans a surface with a detergent when the surface of a base material becomes dirty. There is a drawback that later recovery of hydrophilicity is delayed.

For example, a window glass for a car or a mirror provided in a vanity is often cleaned with a detergent because the surface is easily dirty. However, when the recovery of hydrophilicity after washing is delayed, fine water droplets tend to adhere to the surface, and the antifogging effect is lost.

In order to solve the above problems, the hydrophilic member according to the present invention forms a tin oxide layer directly on the surface of the substrate or with an alkali blocking base film therebetween, and overcoats the surface of the tin oxide layer. ), The overcoat layer is at least one selected from silicon oxide, aluminum oxide, zirconium oxide, cerium oxide, and titanium oxide, and the surface average roughness Ra of the outermost surface. ) Was set to 0.5 to 25 nm.

The preferable range of surface average roughness Ra is 0.5-25 nm, More preferably, it is 5-15 nm. In this range, the long-term stability of the hydrophilic performance is further improved.

When only the tin oxide layer (SnO ₂ ) is formed on the surface of the substrate and the surface of the tin oxide layer (SnO ₂ ) is roughened, it is also described in the prior art (Japanese Patent Laid-Open No. 9-295363). As shown, hydrophilicity is exerted. However, once the surface is cleaned with a bath soap, the contact angle with water is 70 ° to 80 °.

On the other hand, when a thin silicon oxide film (SiO ₂ ) or the like is formed on the surface of the tin oxide layer (SnO ₂ ), the contact angle with water after washing becomes less than 10 °.

This is thought to be super hydrophilic after washing since the tin oxide layer (SnO ₂ ) and the silicon oxide film (SiO ₂ ) are polarized in surface polarity and the bath soap is anionic.

The tin oxide layer (SnO ₂ ) preferably has a rutile crystal structure. By using the tin oxide layer (SnO ₂ ) as a rutile crystal structure, a polycrystalline thin film having a desirable surface irregularities can be formed.

In addition, the surface average roughness Ra of the tin oxide layer SnO ₂ is set to 0.5 to 25 nm, thereby transferring the unevenness to the outermost surface, thereby reducing the surface average roughness Ra of the outermost surface. It can be set to 0.5-25 nm.

If the surface average roughness Ra is smaller than 0.5 nm, it is not preferable because irregularities cannot be formed which are effective for improving long-term retention of hydrophilic properties and performance. Moreover, when surface average roughness Ra exceeds 25 nm, unevenness | corrugation is too large, transparency falls, and long-term stability of hydrophilic performance is low, and it is unpreferable.

In addition, it is preferable that the mean spacing Sm of the unevenness is 4 to 300 nm, and even if the mean spacing Sm of the unevenness is smaller than 4 nm or larger than 300 nm, the long-term stability of the hydrophilic performance and the antifogging performance is low, which is not preferable. . The more preferable range of this average spacing Sm is 5-150 nm. In this range, the long-term stability of the hydrophilic performance becomes better.

Here, as a method of displaying the said surface average roughness Ra, the arithmetic mean roughness Ra defined in JIS B0601 (1994) is used. The value (nm) of arithmetic mean roughness is represented by "the absolute value of the deviation from an average line", and the following formula is given.

[Equation 1]

L: reference length

Moreover, the average space | interval Sm of unevenness | corrugation is also defined by JIS B0601 (1994) similarly to the said surface average roughness Ra. That is, the value (nm) of the average interval of the unevenness is expressed by "the average value of the interval of the one cycle of peak and valley obtained from the intersection where the illuminance curve intersects the average line". Is given.

[Formula 2]

Smi: interval of irregularities (nm)

n: number of intervals of unevenness in the reference length

In addition, as the thickness of the layer of tin oxide (SnO ₂₎ is 10~800 ㎚ is preferable, and preferably 0.1~100 ㎚ The thickness of the overcoat layer such as a silicon oxide film (SiO _2).

If the thickness of the tin oxide layer is smaller or larger than this, desired irregularities cannot be obtained. In other words, if the thickness of the tin oxide layer is smaller than this, a uniform coating is not formed. If the thickness of the tin oxide layer is larger than this, the surface irregularities are large, which is not preferable.

As the alkali barrier base film, a film mainly composed of silicon oxide generally used is suitable. Moreover, additives, such as P (phosphorus) and B (boron), may be added as needed, or it may be set as a complex oxide with tin oxide etc.

In addition, the said alkali blocking base film is formed by a well-known method. For example, a sol-gel method, a liquid phase precipitation method, a vacuum film formation method, a baking method, a spray method, a CVD method, and the like can be exemplified.

Moreover, it is preferable that the said alkali blocking base film is 10 nm or more and 300 nm or less. If the thickness is thinner than 10 nm, the alkali blocking effect is not sufficient, and if the thickness is thicker than 300 nm, the interference color due to the film is remarkably recognized, which makes it difficult to control the optical properties of the glass plate.

Further, as glass, tile, and ceramic or a metal plate is suitable, and the hydrophilic member of the present invention mainly composed of silicon oxide (SiO ₂₎ as the base material, for example, can be applied to the mirror.

1 (a) and 1 (b) are enlarged cross-sectional views of the hydrophilic member according to the present invention, respectively.

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described based on an accompanying drawing. 1 (a) and 1 (b) are enlarged cross-sectional views of the hydrophilic member according to the present invention, respectively.

In the embodiment shown in FIG. 1A, the hydrophilic member forms a tin oxide layer (SnO ₂ ) ₂ on the surface of the glass plate 1 as a substrate, and the tin oxide layer (SnO ₂ ) ( A silicon oxide film (SiO ₂ ) 3 is formed on the surface of 2) as an overcoat layer.

In the embodiment shown in FIG. 1 (b), the base film 4 which prevents alkali such as Na from leaching from the glass plate 1 is interposed between the glass plate 1 and the tin oxide (SnO ₂ ) 2. I'm making it.

In addition, in FIG. 1, Ra represents surface average roughness, and Sm represents the average spacing of unevenness.

The glass plate 1 is made of soda glass containing SiO ₂ as a main component, and the tin oxide layer (SnO ₂ ) 2 is, for example, a sol-gel method, a liquid phase deposition method, a vacuum film forming method, It is formed by conventionally well-known methods, such as a baking method, a spray coat method, a CVD method, and a sputtering method, The thickness is 10-800 nm and the surface average roughness Ra of the surface is 0.5-25 nm. In addition, the tin oxide layer (SnO ₂ ) 2 has a rutile crystal structure.

The silicon oxide film (SiO ₂ ) 3 may be, for example, a sol-gel method, a liquid phase deposition method, a vacuum film formation method, a baking method, a spray coating method, a CVD method, a sputtering method, or the like. It is formed by a conventionally well-known method, and the thickness is 0.1-100 nm. Then, the silicon oxide film (SiO ₂₎ (3) is so formed on the tin layer (SnO _{2) (2)} the oxidation, the irregularities of the tin oxide layer (SnO _{2) (2)} is as transcription, a silicon oxide film ( the average surface roughness (Ra) of the surface of SiO ₂₎ (3) is also a 0.5~25 ㎚.

Moreover, about the average space | interval Sm of unevenness | corrugation, it is suitable to set it as the range of 4-300 nm. Even if the average spacing Sm is smaller than 4 nm and larger than 300 nm, the long-term stability of the hydrophilicity is low, which is not preferable.

Thus, by forming fine unevenness | corrugation on the surface, a hydrophilic surface further improves hydrophilicity.

That is, in the case where the surface area is r times by forming minute unevenness on the surface, if the contact angle with water when the smooth surface is θ and the contact angle with water when the unevenness is formed θ ', cosθ is obtained from Wenzel's equation. '= rcosθ (90 °> θ> θ') holds. However, the case where the contact angle θ deviates greatly from 90 degrees does not fall into this range.

For example, if irregularities are formed on the surface of the member having a 30 ° contact angle when the surface is smooth, and the surface area is 1.1 times, cosθ '= 1.1cos30 ° = 0.935 from the above equation, from which θ' = 17.7 °. Similarly, when surface area is made 1.15 times, (theta) 'becomes 5.2 degrees.

However, this expression does not necessarily hold when θ is small, but θ 'tends to be smaller by providing irregularities.

That is, by forming fine irregularities on the surface, the hydrophilic surface becomes more hydrophilic.

On the other hand, as the base film 4 for alkali blocking purposes, a thin film mainly composed of silicon oxide, a composite oxide film composed of silicon oxide and tin oxide, a silicon oxide film containing carbon, or tin oxide as a main component The film etc. which laminated | stacked the film | membrane whose main component is a silicon oxide are used.

For example, in the composite oxide film made of silicon oxide and tin oxide, or the film of silicon oxide containing carbon, the refractive index thereof is between the refractive index of the glass plate 1 and the refractive index of the tin oxide layer 2, thereby providing a more preferable appearance. You can get it. That is, by setting it as the base film which has an intermediate refractive index, the interference color change (stain) which arises from the fluctuation | variation of the film thickness of a tin oxide layer can be suppressed, and neutralization of a reflection color tone can be aimed at.

In addition, when the base film is a laminate of, for example, a film containing tin oxide as a main component and a film containing silicon oxide as a main component, the apparent refractive index of the laminate is adjusted by adjusting the thicknesses of the laminates. Since the refractive index of the glass plate 1 and the tin oxide layer 2 become intermediate | middle, the same effect as the base film which has the said intermediate refractive index can be acquired.

In addition, when applying the hydrophilic member of the said structure to a mirror, between the back surface of glass plate 1, or between glass plate 1 and base film 4, or when there is no base film, glass plate 1 and tin oxide layer Between (SnO ₂ ) (2), a thin film of metal such as silver is formed, for example.

Next, the film formation method in the Example and comparative example of this invention is demonstrated. Specifically, the sample of Example 1 was produced by sequentially forming a tin oxide film and a silicon oxide film on the glass plate surface using the film forming apparatus (not shown). The samples of Examples 2 to 4 and 6 were produced in the same manner as in Example 1 by sequentially forming a tin oxide film and a silicon oxide film on the glass plate surface. The sample of Example 5 was produced by forming the tin oxide film, the silicon oxide film, the tin oxide film, and the silicon oxide film in order on the glass plate surface similarly to Example 1.

The sample of Comparative Example 1 was produced in the same manner as in Example 1 by sequentially forming a tin oxide film and a silicon oxide film on the glass plate surface. The sample of the comparative example 2 was etched by immersing a glass plate in the aqueous solution which has a hydrofluoric acid as a main component, and forming the fine glass surface of the normal glass plate which consists of a porous film which has a silica as a main component on the glass surface. The samples of Comparative Examples 4 and 5 were prepared by forming a tin oxide film on the glass plate surface in the same manner as in Example 1.

Next, about the sample of the said Example and a comparative example, the average surface roughness Ra and the average space | interval Sm of the unevenness | corrugation were measured. The measurement of these values was observed using the atomic force microscope (AFM) and the electron microscope, and calculated from the measured cross-sectional curve.

In addition, the samples were washed with bath soap and the change in contact angle was measured to confirm the wettability of the sample surface with water. The contact angle with water was measured immediately after washing the sample surface, after 2 hours and after 200 hours.

Tables 1 and 2 below compare the change of contact angle with water after washing with detergent for the hydrophilic member and the comparative example according to the present invention.

TABLE 1

Example One 2 3 4 5 6 Average surface roughness (nm) 10.0 3.0 7.0 13.0 25.0 8.5 Average interval (nm) 40 30 65 110 150 70  Change in contact angle (°) Immediately after cleaning 3.0 5.0 4.0 5.0 10.0 4.0 2 hours later 4.0 10.0 6.0 6.0 12.0 6.0 After 200 hours 10.0 25.0 15.0 13.0 16.0 14.0 Base film composition ―― SiO ₂ SiO ₂ SiO ₂ SnO ₂ / SiO ₂ SiO ₂ Base film thickness (nm) ―― 20 20 20 25/25 20 SnO ₂ film thickness (nm) 350 20 250 600 800 300 Overcoat film thickness (nm) 20 20 50 20 50 50 Remarks

TABLE 2

Comparative Example * One 2 3 4 5 Average surface roughness (nm) 30.0 5.0 1.0 5.0 7.0 Average interval (nm) 250 45 대 (infinity) 50 70  Change in contact angle (°) Immediately after cleaning 57.0 14.0 18.0 70.0 78.0 2 hours later 65.0 18.0 20.0 70.0 79.0 After 200 hours 68.0 32.0 41.0 73.0 80.0 Base film composition SnO ₂ / SiO ₂ ―― ―― ―― ―― Base film thickness (nm) 25/25 ―― ―― ―― ―― SnO ₂ film thickness (nm) 1000 ―― ―― 60 150 Overcoat film thickness (nm) ―― ―― ―― ―― ―― Remarks Comparative Example 2: Glass Plate with Fine Unevenness on Surface by Etching Comparative Example 3: Normal Glass Plate Comparative Example 4: Glass Plate with Tin Oxide Film (SnO ₂ ) Formed on Surface Comparative Example 5: Tin Oxide Film on Surface Glass plate with SnO ₂ )

As is apparent from Table 1, it can be seen that the hydrophilic member according to the present invention has a contact angle with water of 10 ° or less immediately after cleaning, and hydrophilicity lasts for a long time.

On the other hand, as is clear from Table 2, the normal glass plate (comparative example 3) has a contact angle with water immediately after washing, but before and after 10 °, but the contact angle gradually increases with time. This is considered to be because surface irregularities are small (Ra ≒ 1 nm) and hydrophilic persistence is not secured. In addition, although the contact angle with the water immediately after washing | cleaning also the glass plate (Comparative example 2) which formed the fine unevenness | corrugation on the surface by etching, the contact angle becomes large gradually with passage of time. This is presumably because durability is poor because the gap between the unevenness is too small compared with the unevenness of the surface, and the hydrophilic retention performance is also reduced.

In the case where the thickness of the tin oxide film SnO ₂ is formed thicker than the range of the present invention (Comparative Example 1), the silicon oxide film ( the rise and uneven spacing of SiO _2), maintained the hydrophilic performance by this can not be secured. When only the tin oxide film SnO ₂ is formed on the glass plate (Comparative Example 4 and Comparative Example 5), the contact angle with water is 70 ° or more immediately after cleaning, regardless of the thickness of the tin oxide film SnO ₂ . Then hydrophilicity is not shown. This is considered to be due to the properties of the tin oxide film (SnO ₂ ) itself, regardless of the surface shape.

Example 6 is a mirror in which the film | membrane of the structure similar to Example 3 was formed in the surface of the glass plate which silvered on the back surface. This mirror surface does not become cloudy at all even when exhaled, and the contact angle with water becomes 10 degrees or less immediately after washing | cleaning, and it maintains hydrophilicity over the long term. Therefore, it can be said that the mirror of Example 6 has high hydrophilicity and has favorable hydrophilic persistence.

As explained above, according to the 1st characteristic structure of the hydrophilic member of this invention, the contact angle with respect to water becomes small and further hydrophilic long-term stability is obtained.

According to the 2nd characteristic structure of the said hydrophilic member, it becomes possible to form the polycrystalline thin film which has a preferable surface asperity shape, achieving the effect of the said 1st characteristic structure.

According to the third characteristic constitution of the hydrophilic member, while achieving the effect of the first characteristic constitution or the second characteristic constitution, the hydrophilic action at the outermost surface can be sufficiently exhibited, and the recovery of the hydrophilicity after washing is extremely short. It is made, and the lasting effect of hydrophilicity is high.

According to the 4th characteristic structure of the said hydrophilic member, it is possible to maintain hydrophilic performance over a long term, achieving each effect in arbitrary 1 to 3 characteristic structures.

According to the 5th characteristic structure of the said hydrophilic member, desired hydrophilic film can be formed, achieving each function effect in the arbitrary 1st characteristic structure of said 1-4.

According to the sixth characteristic constitution of the hydrophilic member, desired concavities and convexities can be obtained while achieving the respective effects in the arbitrary first to fifth constitutions.

According to the seventh characteristic constitution of the hydrophilic member, since the refractive index of the underlying film is halfway between the refractive index of the glass plate and the tin oxide film, achieving the respective operational effects in any of the first to sixth characteristic constitutions, the interference color change It is possible to suppress (stain) and to neutralize the reflection color tone.

According to the eighth characteristic constitution of the hydrophilic member, the apparent refractive index as the laminate becomes an intermediate between the refractive index of the glass plate and the tin oxide film, while achieving the respective operational effects in any of the first to seventh characteristic constitutions. In addition, the interference color change (stain) can be suppressed and the reflected color tone can be neutralized.

According to the ninth feature configuration of the hydrophilic member, mirrors, window panes for automobiles, antifogging antifouling glass for building, and spectacles can be achieved while achieving respective effects in any of the first to eighth feature configurations. It can be effectively applied to applications such as lenses, tiles, or metal plates.

According to the 10th characteristic structure of the said hydrophilic member, it can be effectively applied to uses, such as an automobile rearview mirror, a bathroom mirror, etc., achieving each effect in arbitrary 1 to 9 characteristic features.

Claims (10)

A tin oxide layer is formed on the surface of a substrate made of silicon, oxide, glass, tile, ceramics, or metal plate directly or with an alkali barrier layer therebetween, and an overcoat layer is formed on the surface of the tin oxide layer. It is a hydrophilic member, The overcoat layer consists of at least 1 sort (s) chosen from silicon oxide, aluminum oxide, zirconium oxide, cerium oxide, and titanium oxide, and the surface average roughness Ra of the outermost surface is 0.5. It is -25 nm, The hydrophilic member characterized by the above-mentioned. The hydrophilic member according to claim 1, wherein the tin oxide layer has a rutile crystal structure. The hydrophilic member according to claim 1, wherein the surface average roughness Ra of the tin oxide layer is 0.5 to 25 nm, and the surface average roughness Ra of the outermost surface is 0.5 to 25 nm. The hydrophilic member according to claim 1, wherein the average spacing Sm of the uneven surface of the outermost surface is 4 to 300 nm. The hydrophilic member according to claim 1, wherein the tin oxide layer has a thickness of 10 to 800 nm. The hydrophilic member according to claim 1, wherein the overcoat layer has a thickness of 0.1 to 100 nm. The hydrophilic member according to claim 1, wherein a refractive index of the base film for alkali blocking is an intermediate value between the refractive index of the substrate and the refractive index of the tin oxide layer. The hydrophilic member according to claim 1, wherein the base film is a laminate of a tin oxide layer and a silicon oxide layer. delete The hydrophilic member according to any one of claims 1 to 8, wherein the hydrophilic member is a mirror in which a metal thin film is formed between the back side of the substrate, the substrate and the tin oxide layer, or between the base film and the tin oxide layer.

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