JP4788871B2 - Super hydrophilic member - Google Patents

Description

The present invention relates to a member characterized by exhibiting super hydrophilicity obtained by applying a dispersion liquid in which fine particle metal oxides are dispersed in non-volatile silicone on a base material and baking it.
More specifically, the present invention forms a silicon dioxide (silica) -based coating film carrying a particulate metal oxide on the surface of a member so that it is mechanically stable after firing and has a contact angle with purified water of 10 The present invention relates to a member characterized by exhibiting superhydrophilicity of a degree or less.

  Conventionally, various techniques for making surfaces of various members superhydrophilic have been tried. For example, a layer containing a photocatalytic titanium oxide and a composite oxide of silicon and titanium is formed, or a photocatalytic titanium oxide-containing layer is formed, and a layer of silicon and titanium is further formed thereon. Recently, a method for obtaining super hydrophilicity using a photocatalyst, such as a photocatalytic hydrophilic member (Patent Document 1) in which a layer containing a composite oxide is formed, has become a hot topic. Also, a dehydration-condensable titania sol obtained from titanium alkoxide and 2-methyl-2,4-pentanediol and a film containing a composite of amorphous oxide and silica fine particles by dehydration-condensation polymerization. And a method of forming a hydrophilic coating by baking an organometallic compound such as alkoxysilane or alkoxytitanium itself as a solvent, as in a method for producing a hydrophilic coating characterized in that (Patent Document 2). It has been. In the latter case, a film containing silica fine particles can be formed during firing.

  Similarly, a silicon alkoxide is baked to form a hydrophilic film, and a compound comprising silicon alkoxide and nitric acid as an oxidizing agent is baked in the presence of titanium dioxide, chromium oxide, iron oxide or the like to make hydrophilic film. The formation of a coating (Patent Document 3) and the application of the coating to a heat exchanger and an evaporator (Patent Document 4) are disclosed, and further baking and baking of silicon alkoxide on these baked films Discloses a method for forming a hydrophilic film by the method (Patent Document 5). Also disclosed is a method for producing a hydrophilic coating (patent document 6) in which a composite solution comprising a titania-containing metal oxide sol and colloidal silica is applied and baked on a substrate, and disclosed as colloidal silica, colloidal alumina, silicic acid. A hydrophilic member (Patent Document 7) for applying and baking a composite of sodium, potassium silicate, and colloidal zirconia is also disclosed, but none is a member exhibiting super hydrophilicity.

Japanese Patent Laid-Open No. 10-085610 JP 2003-176426 A JP 05-302173 A Japanese Patent Laid-Open No. 05-302174 Japanese Patent Laid-Open No. 05-306991 JP-A-10-060665 JP 2001-294849 A

  However, since photocatalysts use radicals for the principle of hydrophilic expression, there are problems such as deterioration of the resin that is the base material over time, and performance cannot be exhibited unless exposed to light (ultraviolet rays). It was. In addition, when forming a coating film using an organometallic compound, the organometallic compound is expensive and may have high volatility and flammability. There is a problem that the manufacturing process becomes complicated and the manufacturing cost becomes high, such as having to be introduced at some stage of the manufacturing process.

  As a result of diligent research in view of these problems, the inventors of the present invention do not obtain an inorganic oxide from an organometallic compound by firing, but more easily by firing using a stable and inexpensive silicone compound. It was found that a hydrophilic film can be formed safely. Furthermore, it has been found that superhydrophilicity is manifested by introducing a fine particle metal oxide here, although it does not show superhydrophilicity only by firing a silicone compound. And since the member obtained is a silica film incorporating inorganic oxide particles, the appearance can be arbitrarily adjusted in the range of transparent to opaque by changing the type, particle size and content of the inorganic oxide. In addition, the present inventors have found that it is possible to control the ultraviolet ray preventing effect and the light scattering property of the coating film.

  The invention described in the present application includes the following first to ninth inventions (hereinafter collectively referred to as “the present invention” unless otherwise specified). That is, the first invention of the present application is a member characterized by exhibiting super hydrophilicity obtained by applying a dispersion liquid in which a fine particle metal oxide is dispersed in nonvolatile silicone onto a base material and baking it. is there.

  According to a second aspect of the present invention, the nonvolatile silicone is selected from methyl hydrogen polysiloxane, dimethyl polysiloxane methyl hydrogen polysiloxane copolymer or silicone resin.

  According to a third aspect of the present invention, there is provided the above member, wherein the average primary particle diameter of the fine particle metal oxide dispersed in the nonvolatile silicone is in the range of 1 nm to 100 μm.

  In a fourth invention of the present application, the fine particle metal oxide contains at least one of titanium oxide, zinc oxide, silicon dioxide, aluminum oxide, zirconium oxide, iron oxide, cerium oxide, tungsten oxide, cobalt oxide, or tin oxide. There exists in said member characterized by these.

  A fifth invention of the present application resides in the above member, wherein the fine particle metal oxide is surface-treated with a surface treatment agent containing at least one of silicon dioxide, a silicone compound or a silane compound.

  A sixth invention of the present application resides in the above member, wherein the firing temperature of the dispersion is in the range of 300 to 1200 ° C.

  The seventh invention of the present application is a modified organopolysiloxane selected from at least one of a polyether-modified organopolysiloxane, an alkyl / polyether-modified organopolysiloxane, a polyglyceryl-modified organopolysiloxane, or an alkyl-modified organopolysiloxane as a dispersant. Is contained in the member described above.

  The eighth invention of the present application resides in the above-mentioned member, wherein the contact angle between the surface of the coating formed by firing the dispersion and purified water is 10 degrees or less.

  A ninth invention of the present application resides in the above member, wherein the base material is made of at least one selected from glass, tile, ceramics, metal plate or brick.

  As described above, in the present invention, there is provided a member that exhibits super hydrophilicity obtained by applying a dispersion liquid in which fine particle metal oxides are dispersed in non-volatile silicone on a base material and baking the dispersion. can get. Superhydrophilicity is manifested by the presence of metal oxide particles in the coating film. This is because the silicone resin undergoes volumetric shrinkage during firing and the reaction on the coating film surface during reaction such as generation of combustion gases. It is considered that superhydrophilicity is expressed. In addition, examples of usable applications of the member obtained in the present invention include window glass that does not have water droplets, glass that is not easily fogged, tiles that are not easily soiled, and exterior wall materials.

  The non-volatile silicone used in the present invention refers to a non-volatile silicone compound at room temperature and normal pressure. For example, methyl hydrogen polysiloxane, dimethyl polysiloxane methyl hydrogen polysiloxane copolymer, silicone resin, dimethyl polysiloxane, alkyl-modified Silicone compounds such as organopolysiloxanes, amino-modified organopolysiloxanes, dimethiconols or dimethylpolysiloxane gums are mentioned, but they are particularly reactive and form a strong film on the substrate during the temperature rising process during firing, It is preferably selected from at least one of methyl hydrogen polysiloxane, dimethyl polysiloxane, methyl hydrogen polysiloxane copolymer or silicone resin, which has the property of hardly flowing at high temperatures. The viscosity of the non-volatile silicone is not particularly limited, and it can be used by a method of diluting with a solvent even if it has a high viscosity such as gum.

  The solvent used for adjusting the viscosity of the non-volatile silicone is preferably selected from at least one of decamethylcyclopentasiloxane, methyltrimethicone, tetrakistrimethylsiloxysilane, toluene, xylene or light isoparaffin. It is preferable to use a solvent having a high boiling point under 1 atm of 100 to 260 ° C. Within this range, there is a merit that the safety in operation at the time of mechanical grinding is high. Examples of these include decamethylcyclopentasiloxane (boiling point 210 ° C.), methyltrimethicone (boiling point 190 ° C.) or tetrakistrimethylsiloxysilane (boiling point 222 ° C.).

  As the fine metal oxide used in the present invention, a metal oxide having an average primary particle diameter in the range of 1 nm to 100 μm can be used, and the shape thereof is spherical, substantially spherical, rod-shaped, spindle-shaped, plate-shaped, Any shape such as indefinite shape is acceptable. Examples of the particulate metal oxide preferably include at least one of, for example, titanium oxide, zinc oxide, silicon dioxide, aluminum oxide, zirconium oxide, iron oxide, cerium oxide, tungsten oxide, cobalt oxide, or tin oxide. It is preferable to contain at least one of titanium oxide, zinc oxide, silicon dioxide, aluminum oxide, zirconium oxide or cerium oxide. These metal oxides are safe and have excellent properties during firing.

  In the present invention, these fine particle metal oxides are preferably surface-treated with a surface treatment agent containing at least one of silicon dioxide, a silicone compound or a silane compound. For example, in the case of octylsilane-treated fine particle metal oxide which is one kind of silane compound and methylhydrogenpolysiloxane-treated fine particle metal oxide which is one kind of silicone compound, nonvolatile silicone which becomes a medium at the time of dispersion And has the merit of forming a stable dispersion. Also, if the particulate metal oxide has an activity such as photocatalytic activity, the coating film may deteriorate over time. However, if it is treated with silicon dioxide, a silicone compound or a silane compound, the photocatalytic activity significantly decreases. However, there is a feature that positively affects the long-term stability of the coating film.

  In the present invention, a dispersion in which fine particle metal oxide is dispersed in non-volatile silicone is applied on a substrate. As a method of dispersing fine particle metal oxide in non-volatile silicone, the surface of fine particle metal oxide is used. Used in combination with a method that uses mechanical dispersion, such as a method that uses a surface treatment agent to improve dispersion stability by using a surface treatment agent, or a method that uses a surfactant to increase the stability of particulate metal oxides. It is preferable to do.

  The surfactant used herein is preferably a silicone-based surfactant having a characteristic that it can be converted to silica after firing. For example, polyether-modified organopolysiloxane, alkyl-polyether-modified organopolysiloxane, polyglyceryl-modified organopolysiloxane Alternatively, it is preferable to use a modified organopolysiloxane selected from at least one of alkyl-modified organopolysiloxanes.

  Further, as a mechanical dispersion method, a dispersion method using a disper, an attritor, a homomixer, or the like, a method of spraying a slurry at high pressure, a medium type pulverizer such as a paint shaker, a sand mill or a pebble mill, a roll mill, etc. And the like. Dispersing using a disper, attritor, homomixer, etc. has the advantage of being inexpensive and easy to work, a method of spraying slurry at high pressure, a medium type crusher such as a paint shaker, sand mill or pebble mill, roll mill, etc. The method of using can be highly dispersed, and is a preferable method when importance is attached to the transparency and appearance of the coating film.

  The dispersion of the present invention preferably contains 1 to 60 parts by weight of fine particle metal oxide and 1 to 99 parts by weight of non-volatile silicone in 100 parts by weight of the composition, particularly fine particle metal oxide. The weight ratio of non-volatile silicone is preferably in the range of 1:99 to 60:40. If it exists in this range, a particulate metal oxide will be easily fixed to the silica converted from the non-volatile silicone.

As the coating method used in the present invention, any method such as coating with a uniform thickness using an applicator or a roll coater, coating with a brush or the like, or immersing the substrate in a dispersion liquid is used. You may use.
However, when thickly applied, there is a problem that the strength of the coating film becomes uneven or the strength is weakened. If possible, the coating film after baking should be applied to a thickness of 500 μm or less. preferable.

  In this invention, the member which apply | coated the dispersion liquid on the base material as mentioned above is baked. As the firing conditions used in the present invention, the firing temperature in the oxygen-containing atmosphere is in the range of 300 to 1200 ° C, more preferably in the range of 300 to 600 ° C. If the temperature exceeds 1200 ° C., there is a problem that the base material is distorted, cracked or melted. However, when the heat resistance of the substrate is sufficient and the strength of the coating film surface is required, it may be fused at a temperature higher than that.

  Further, the firing time is set in a range of 0.5 to 48 hours suitable for process control, and the firing temperature may be raised in multiple steps or may be raised slowly. If the furnace temperature at the time of firing is placed in the range of 100 to 250 ° C for 30 minutes or more, the reaction proceeds if a reactive silicone is used as a non-volatile silicone at this stage, and a dense coating film is formed. Since it forms, it is preferable. Moreover, since there are problems such as cracking of the base material when rapidly cooled, it is preferable to cool slowly.

  Examples of the base material used in the present invention include glass, tile, ceramics, metal plate, brick, and the like, and a base material composed of at least one selected from glass, tile, or ceramics is particularly preferable.

  In the present invention, it is necessary that the member obtained by applying and baking the dispersion exhibits super hydrophilicity. The term “superhydrophilic” as used in the present invention means that the static contact angle between the member coating surface and purified water is 10 degrees or less, and more preferably 6 degrees or less.

  Next, prediction of the superhydrophilic mechanism of the present invention will be shown. Usually, when silica particles are coated on a smooth substrate and the contact angle between the surface of the silica particles and purified water is measured, super hydrophilicity may be exhibited. In this case, since the silica particles are not fixed on the base material, they can be used as an industrial member because they fly away if the wind blows. When a silica film is formed on the material, it becomes hydrophilic but does not show super hydrophilicity.

  Furthermore, the surface of the glass plate has a structure similar to silica and is covered with silanol, but does not exhibit super hydrophilicity. This shows that there is a difference in behavior even with the same silica. For this reason, when silica particles are applied, it is highly possible that superhydrophilicity is manifested using the capillary force of water.

  Looking at the members of the present invention, this coating film is different in that the metal oxide particles are contained in the coating film obtained by applying and baking the silicone resin, but it exhibits super hydrophilicity. Silicone resin undergoes many reactions such as volume shrinkage and generation of combustion gas during firing. At this time, a fine structure is formed on the surface of the coating film, and the capillary force interacts with this structure in some way, making it super hydrophilic. It is possible that is expressed.

  Applications that can be used for the member obtained in the present invention include window glass that does not have water droplets, glass that resists fogging, tiles or exterior wall materials that resist dirt, and the like.

Hereinafter, the present invention will be described in detail by way of examples and comparative examples.
Moreover, the evaluation method used by the Example and the comparative example is shown below.

Contact angle measurement method The sample was measured using a DropMaster500 contact angle measuring device manufactured by Kyowa Interface Science Co., Ltd. Distilled water was used as water. The amount of water droplets during measurement was 1.5 μL, and analysis software FAMAS manufactured by the same company was used for contact angle analysis. Moreover, the sample used for the measurement was dried again, and the measurement of the contact angle was repeated, and it was confirmed whether or not the superhydrophilicity was maintained by repeated contact with water. The coating was performed using a doctor blade with a coating thickness of 0.013 mm.

[Example 1]
24 parts by weight of a slurry of highly dispersed decylmethylcyclopentanesiloxane (volatile silicone) in a concentration of 35% by weight of octylsilylated surface-treated fine particle titanium oxide having an average primary particle size of 35 nm and dimethylpolysiloxane (Shin-Etsu Chemical) After applying a slurry obtained by mixing 10 parts by weight of KF-96A 20cs, non-volatile silicone) and 66 parts by weight of decamethylcyclopentasiloxane on a glass plate, the slurry was dried under an air flow of 50 ° C. Baked at 500 ° C. for 1 hour. The contact angle before firing was 104 degrees, but after firing was less than 5 degrees, indicating super hydrophilicity. Moreover, this member repeatedly performed contact angle measurement, and was able to reproduce super hydrophilicity stably also in the test which confirms coating-film strength.

[Example 2]
24 parts by weight of a slurry of highly dispersed octylsilylated surface-treated fine particle zinc oxide having an average primary particle size of 10 nm in decamethylcyclopentasiloxane at a concentration of 35% by weight, and methylhydrogenpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.) A slurry in which 10 parts by weight of KF-99P) and 66 parts by weight of decamethylcyclopentasiloxane were mixed was coated on a glass plate, dried under an air flow of 50 ° C, and then at 500 ° C for 1 hour. Baked. The contact angle before firing was 89 degrees, but after firing it was 6 degrees, indicating super hydrophilicity. Moreover, this member repeatedly performed contact angle measurement, and was able to reproduce and confirm super hydrophilicity stably also in the test which confirms coating-film strength.

Example 3
A paste containing 24 parts by weight of untreated silica with an average primary particle size of 30 nm, 66 parts by weight of decamethylcyclopentasiloxane, and 10 parts by weight of methyl hydrogen polysiloxane (KF-9901 manufactured by Shin-Etsu Chemical Co., Ltd.) on a glass plate After coating and drying under an air flow of 50 ° C., baking was performed at 700 ° C. for 1 hour. The contact angle before firing was 17 degrees, but after firing was less than 5 degrees, indicating super hydrophilicity. Moreover, this member repeatedly performed contact angle measurement, and also showed super hydrophilicity stably also in the test which confirms coating-film strength.

Example 4
24 parts by weight of granulated silica with a secondary particle size of 1 μm, 24 parts by weight, 20 parts by weight of 50% by weight trimethylsiloxysilicic acid (silicone resin) decamethylcyclopentasiloxane, and decamethylcyclopentasiloxane 56 The slurry mixed with parts by weight was dried under blowing at 50 ° C. and then fired at 500 ° C. for 1 hour. The contact angle before firing was 109 degrees, but after firing, it was less than 5 degrees, indicating super hydrophilicity. Moreover, this member repeatedly performed contact angle measurement, and was able to confirm super hydrophilicity stably also in the test which confirms coating-film intensity | strength.

[Comparative Example 1]
Applying 50% by weight of decamethylcyclopentasiloxane solution of trimethylsiloxysilicic acid (silicone resin) directly to glass without blending fine particle metal oxide, and drying under blowing at 50 ° C, then at 500 ° C Baked for 1 hour. The contact angle before firing was 108 degrees, the contact angle after firing was 20 degrees, and although it was hydrophilic, it did not show super hydrophilicity.

[Comparative Example 2]
When untreated silica with an average primary particle size of 30 nm was applied directly to glass and the contact angle was measured, the contact angle was less than 5 degrees, indicating super hydrophilicity. It could not be used as a sex member.

[Comparative Example 3]
A paste prepared by mixing 24 parts by weight of untreated silica with an average primary particle size of 30 nm, 66 parts by weight of decamethylcyclopentasiloxane, and 10 parts by weight of octyl paramethoxycinnamate (oil) on a glass plate was blown at 50 ° C. After drying down, it was fired at 500 ° C. for 1 hour. Although the contact angle before firing was 15 degrees, it became less than 5 degrees after firing, indicating super hydrophilicity. However, this member had a problem in strength because the coating film was broken by the degree of contact with the finger.

Claims (4)

Surface treatment containing at least one of silicon dioxide, silicone compound or silane compound in one or more kinds of non-volatile silicone selected from methyl hydrogen polysiloxane, dimethyl polysiloxane methyl hydrogen polysiloxane copolymer or silicone resin Titanium oxide, zinc oxide, aluminum oxide, zirconium oxide, iron oxide, cerium oxide, tungsten oxide, cobalt oxide, tin oxide , and silicone, whose average primary particle size is surface-treated with an agent is in the range of 1 nm to 100 μm Particulate metal oxide containing at least one selected from silicon dioxide having an average primary particle diameter in the range of 1 nm to 100 μm which is surface-treated with a surface treatment agent containing at least one of a compound or a silane compound It is obtained by applying a dispersion with dispersed on a substrate and baking it. A member having a contact angle between the coating surface and purified water of 10 degrees or less.   The member according to claim 1, wherein the firing temperature is in the range of 300 to 1200 ° C.   As a dispersant, a modified organopolysiloxane selected from at least one of polyether-modified organopolysiloxane, alkyl-polyether-modified organopolysiloxane, polyglyceryl-modified organopolysiloxane, or alkyl-modified organopolysiloxane is blended. The member according to claim 1 or 2, characterized in that:   The member according to any one of claims 1 to 3, wherein the substrate is made of at least one selected from glass, tile, ceramics, metal plate or brick.