JP2005315073A - Base material with antifouling layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base material remarkably superior in antifouling performance even when exposed outdoors over a long period. <P>SOLUTION: This base material with the antifouling layer has the antifouling layer having an OH group on a surface; and is constituted so that after dripping silicone oil on the surface, the silicone oil is made to flow down by inclining the base material at 60°, and next, water of 1.5 liters is poured on the base material surface for 15 sec, and a contact angle of water of a silicone oil flowed-away part when dried thereafter, becomes 40° or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a base material with an antifouling layer, and more particularly to a base material with an antifouling layer having a self-cleaning function that is difficult to get dirty for a long period of time when constructed on a building outer wall using a silicon-based sealing material.

  When a super-hydrophilic film is formed on the surface of a substrate such as a tile, when water adheres to the surface of the substrate, the water spreads on the surface of the film, and the dirt spreads along the surface of the film together with rainwater and flows down. It is known that the surface of the material is less likely to get dirty and less noticeable.

  As such a superhydrophilic film having a self-cleaning function, a titanium oxide (TiO2) film is widely used.

  Japanese Patent Application Laid-Open No. 10-158585 includes 2.5 to 15 parts by weight of acidic colloidal silica, 0.1 to 15 parts by weight of an amine compound, 10 to 80 parts by weight of an inorganic filler such as silica, alumina or mullite, water or A coating composition comprising 17 to 87 parts by weight of a hydrophilic organic solvent (100 parts by weight in total) is applied to the surface of cement, concrete, glass, ceramics, etc., and heated at 30 to 200 ° C. Is cured to form a coating film that is hydrophilic and hardly adheres to dirt.

  In JP-A-10-330646, a paint containing soluble potassium silicate and aqueous silica sol is applied to a steel sheet and heated to 150 to 250 ° C., thereby forming a coating film that is hydrophilic and excellent in stain resistance. Is described.

JP-A-10-158585 Japanese Patent Laid-Open No. 10-330646

  In a building window, a silicon-based sealing material is filled between a window glass plate and a window frame (sash) that supports the window glass plate. In addition, the silicon sealing material may be filled in the joints between the tiles.

  When rain hits the outer wall surface using such a silicon-based sealing material, the silicon oil is gradually eluted from the silicon-based sealing material, and the silicon oil adheres to the tile surface. Since this silicone oil has a high affinity with organic substances, if the silicone oil adheres to the tile surface, organic stains are likely to adhere to the tile surface. In addition, since silicon oil has water repellency, water containing inorganic dirt such as dirt is repelled from the silicon oil adhesion area and flows down along the outer edge of the silicon oil adhesion area. A large amount of dirt adheres to the surface. In this case, there is little inorganic dirt in the silicon oil adhesion area, and a large amount of dirt adheres to the outer edge area, so that the contrast between the two becomes remarkable, and the outer wall surface of the building becomes not very dirty.

  As a result of various studies by the present inventor, the titanium oxide-based superhydrophilic coating has a high affinity with the silicon oil. Therefore, the outer surface of the building on which the titanium oxide-based superhydrophilic tile is constructed is a photocatalyst in the initial stage. Although the organic matter decomposing effect is observed and the antifouling effect is exhibited, in the long term, the decomposing effect is gradually hindered, resulting in an antifouling performance that is not significantly different from ordinary tiles.

  Further, since the titanium oxide-based superhydrophilic film utilizes the photocatalytic action of TiO2, the antifouling property due to the original hydrophilicity is not exhibited at night when light is not applied.

  The coating films disclosed in JP-A Nos. 10-158585 and 10-330646 have hydrophilicity and stain resistance, but have almost no hygroscopic property and insufficient antifouling properties.

  An object of the present invention is to provide a substrate with an antifouling layer that is remarkably excellent in antifouling properties over a long period of time when constructed on an outer wall of a building using a silicon-based sealant.

  The substrate with an antifouling layer of the present invention is a substrate with an antifouling layer having an antifouling layer on the surface, and after dripping silicon oil onto the surface, the substrate is inclined at 60 ° to flow down the silicon oil. Then, 1.5 liters of water is poured onto the surface of the substrate for 15 seconds, and then the contact angle of water in the portion from which the silicone oil has been washed away is 40 ° or less. .

  This antifouling layer is preferably composed of a hygroscopic layer. In such a substrate with a moisture absorbing layer, a thin water film is formed on the surface when the moisture absorbing layer absorbs moisture, which makes it extremely difficult to be soiled.

  The base material with an antifouling layer of the present invention has a surface activity that makes it difficult for silicon oil to adhere to it, and when applied to the outer wall surface of a building, the occurrence of easily noticeable dirt due to the adhesion of silicon oil occurs. Suppressed and long-term appearance is obtained.

  In the present invention, the difficulty in adhering the silicone oil is caused to adhere to and flow out of the surface of the substrate with the antifouling layer by a specific method as described above, and then the dried silicone oil is washed away. It is specified by the water contact angle of the part.

  As is well known, the contact angle of water is small when the solid surface is more hydrophilic, and the contact angle of water is large when the solid surface is more lipophilic. In the present invention, when the silicon oil is adhered as described above, and then drained and dried, the contact angle of water is 40 ° or less.

  Accordingly, even when the water containing silicone oil flows along the outer wall of the building, the silicon oil does not adhere to the surface of the base material, and the dirt resulting from the silicon oil adhesion is reduced. .

  According to the present invention, even when exposed outdoors, a substrate having a significantly excellent antifouling property over a long period of time is provided.

  The substrate with an antifouling layer of the present invention has an antifouling layer on the surface, and the antifouling layer is preferably composed of a hygroscopic layer, and the hygroscopic layer preferably contains silica particles. The silica particles are preferably porous silica particles. The silica particles are preferably amorphous silica particles. The silica particles preferably have a particle size of 50 nm or less, particularly 25 nm or less. Since the silica particles are hydrophilic, a sufficiently high hygroscopic property is imparted to the coating containing the fine silica particles.

  The silica particles are preferably present in the moisture-absorbing layer in an amount of 50% by weight or more (hereinafter, unless otherwise specified,% indicates% by weight), particularly 85% or more.

  When the silica particles are porous, the hygroscopic property of the hygroscopic layer is improved. Further, when the silica particles are amorphous, the hygroscopicity can be further enhanced by the presence of more OH groups on the surface.

  The hygroscopic layer preferably contains an alkali silicate component derived from water glass as a film-forming component as a component other than the silica particles. This alkali silicate is preferably present in the hygroscopic layer in an amount of 0.1 to 50%, particularly 1.0 to 20%.

  The moisture absorption layer may further contain 0.01 to 1%, particularly 0.04 to 0.9%, of an aluminum component, specifically, one or more of alumina, aluminum silicate, and a water-soluble aluminum compound. good. By including this aluminum component, the moisture absorption layer is greatly improved in water resistance reduction due to the mixing of water glass. In order to increase the reactivity with water glass, the aluminum component is preferably a water-soluble aluminum compound or fine particles having a particle diameter of 10 μm or less, particularly 1 μm or less, if alumina and / or aluminum silicate.

 The thickness of the hygroscopic layer is preferably 1000 nm or less, particularly 50 to 200 nm. If the thickness of the hygroscopic layer exceeds 1000 nm, peeling of the coating tends to occur. In addition, when a moisture absorption layer is too thin, it will become difficult to form a moisture absorption layer in the whole base material without a pinhole.

  In order to form the hygroscopic layer on the substrate surface, a paint containing colloidal silica and water glass may be applied to the substrate surface and heated to 120 ° C. or higher. By this heating, the water glass is cured and the coating film is firmly fixed to the substrate surface.

  As described above, the colloidal silica preferably has a particle size of 50 nm, particularly 25 nm or less.

  The preferred blending ratio of this paint is as follows.

Colloidal silica (converted to anhydrous basis): 50-99%
Water glass (converted to anhydrous base): 0.5-48.5%
Aluminum component: 0.01 to 3.5%
In order to apply this paint to the surface of the substrate, application using a roll coater, spin coating, spraying, curtaining, etc. can be employed. After application, the glass is dried as necessary and then heated to 120 ° C. or higher, preferably 300 to 700 ° C., to cure the water glass. If the heating temperature at this time is lower than 120 ° C., the moisture absorption layer has insufficient hardness and water resistance. It should be noted that, by heating at a high temperature of 300 to 700 ° C., preferably for 5 to 30 minutes, a moisture absorbing layer having sufficiently high hardness and sufficiently high water resistance and moisture absorbing properties is formed. When the heating temperature is higher than 700 ° C., the hygroscopicity of the hygroscopic layer may be reduced due to melting or crystallization of the glass component in the hygroscopic layer.

  In the present invention, the base material is preferably a tile constructed on the outer wall of a building, particularly on the lower side of a window, but is a toilet bowl, bathtub, unit bath wall, basin, faucet fitting, mirror, glassware, Also good. The tiles may be glazed or unglazed.

Example 1
An antifouling coating was applied to the ceramic tile surface to produce a substrate (tile) with an antifouling layer (moisture absorbing layer) of the present invention.

  The raw materials for the antifouling treatment and the blending ratio thereof are as follows.

Colloidal silica slurry (solid content 10%): 10 parts by weight Sodium silicate 3: 1 part by weight Aluminum silicate: 0.03 parts by weight The above raw materials were uniformly mixed to prepare a paint for antifouling treatment. This paint was applied to the surface of the tile (45 mm × 95 mm × 6 mm glazed tile) by spraying. The coating amount was 2 g / m2.

  This tile with a moisture absorption layer is horizontally upward, and 0.01 g of silicon oil (product number KF-96-100CS manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight 5000) is dropped at a position 20 mm away from the center of the short side as shown in FIG. did. Next, the tile is inclined 60 ° vertically as shown in FIG. 1, and a funnel is used so that 1.5 liters of water (20 ° C.) does not rebound for 15 seconds toward a position 10 mm from the upper side. I poured it quietly.

  The diameter (diameter) of the lower end of the funnel was 10 mm, and the lower end of the funnel was arranged at a height of 100 mm vertically above the point where water was poured.

  Thereafter, the tile was dried at 80 ° C. for 10 minutes. When the contact angle of water was measured at the position shown in FIG. 1, it was 15 °.

Example 2
A substrate (tile) with a hygroscopic layer was produced in exactly the same manner as in Example 1 except that the coating amount of the antifouling coating was 4 g / m @ 2, and after dripping, running off and drying of silicon oil in the same manner. The water contact angle on the tile surface was measured at the position shown in FIG.

Comparative Example 1
For the tile of Example 1 to which no antifouling paint was applied, silicon oil was dropped, washed away and dried in the same manner as in Example 1, and the contact angle of water was measured at the contact angle measurement position. As a result, it was 60 °.

Comparative Example 2
Instead of the antifouling treatment paint, 2 g / m 2 of TiO 2 slurry (solid content 10%) was applied and baked at 600 ° C. to be baked on the surface. Except that the antifouling layer was composed of TiO2 in this way, a substrate (tile) with a hygroscopic layer was produced in exactly the same manner as in the examples, and the silicone oil was dropped, washed away and dried in the same manner. When the contact angle of water was measured at the contact angle measurement position, it was 45 °.

  Further, the antifouling properties of the tiles of Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated by an outdoor exposure test as follows.

  [Anti-fouling performance test method] Twelve 45 × 95 × 6 mm tiles were pasted on a flexible board with a joint spacing of about 5 mm, and the joints were sealed with silicon.

  A sample (flexible board) with the silicone sealant applied to the joint was subjected to an exposure test outdoors for 300 days. There was rainfall for 90 days during this test period.

  The dirtyness of the tile surface after the elapse of 300 days was evaluated in the following four grades A to D.

A: Dirt is hardly noticeable. B: Dirt is slightly noticeable. C: Dirt is noticeable. D: Dirt is noticeably noticeable and feels dirty.

  As a result, each of Examples 1 and 2 was A evaluation, Comparative Example 1 was D evaluation, and Comparative Example 2 was C evaluation.

Illustration of silicon oil adhesion and runoff method

Claims (4)

A substrate with an antifouling layer having an antifouling layer on the surface, and after dripping silicon oil onto the surface, the substrate is tilted at 60 ° to allow the silicon oil to flow down, and then 1.5 liters for 15 seconds. A base material with an antifouling layer, wherein a contact angle of water in a portion where the silicon oil is poured when water is poured onto the surface of the base material and then dried is 40 ° or less. 2. The substrate with an antifouling layer according to claim 1, wherein the antifouling layer comprises a moisture absorbing layer containing silica particles. 3. The substrate with an antifouling layer according to claim 2, wherein the silica particles are porous silica particles. 4. The substrate with an antifouling layer according to claim 2, wherein the silica particles are amorphous.

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