JP2005281443A - Hydrophilic membrane and its formation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrophilic membrane which is excellent in hydrophilicity and durability against various acidic, neutral and alkaline detergents and drugs and has a high hardness, and its formation method. <P>SOLUTION: The hydrophilic membrane is intended for covering and protecting a flat substrate and is composed of a coating film containing a multiple oxide consisting of silicon and zirconium, an alkaline earth metal and water or containing a mixture of a silicon oxide and a zirconium oxide, an alkaline earth metal and water. Here, pores at a surface layer of the coating film are filled with a hydrate of a silicate of an alkaline earth metal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydrophilic film for covering and protecting a planar substrate made of various materials such as metals, organic compounds, and inorganic compounds, and a method for forming the hydrophilic film.

A technique is widely used in which a hydrophilic film is formed on the surface of a planar substrate, and the surface of the planar substrate is protected by this hydrophilic film, or dirt or the like is hardly attached to the substrate surface. .
As a method for forming a hydrophilic film, the following methods have been proposed.
(1) A method of applying a surfactant.
(2) A method of applying a water absorbent resin.
(3) A method of applying a hydrophilic photocatalyst.
(4) A method of forming a film made of an inorganic compound such as a silica film by repelling or ceramic spraying.
(5) A method of applying a resin coating agent containing a hydrophilic component.
For example, Patent Document 1 discloses a hydrophilic coating film using a photocatalyst.
JP 2000-191960 A

However, the hydrophilic films formed by these methods have problems in various properties such as durability against alkaline solutions, hot water, and detergents as described below.
In the method (1), a hydrophilic film composed of a surfactant is formed. Since the surfactant is water-soluble, the hydrophilic film is easily dissolved in water or a detergent, and the effect of the hydrophilic film disappears in a short time.
In the method (2), a hydrophilic film composed of a water absorbent resin is formed. Since the water-absorbent resin is deteriorated by an acidic or alkaline detergent, the hydrophilic film has a problem of poor durability against the detergent.
In the method (3), a hydrophilic film composed of a photocatalyst is formed. However, this hydrophilic film has a problem that an effect cannot be sufficiently obtained in a dark place.
Moreover, when using a hydrophilic photocatalyst, it is necessary to use a silica binder in order to fix this hydrophilic photocatalyst. Since the silica binder is easily deteriorated by an alkaline or neutral detergent, the hydrophilic film fixed by the silica binder has a problem of poor durability against the detergent.

In the method (4), for example, when a hydrophilic film is formed by squeezing or ceramic spraying, usable materials are limited to heat resistant materials, and the formed hydrophilic film has a problem that it is vulnerable to impact. .
Further, when a silica film is formed as a hydrophilic film, the silica film has a problem in that it is easily deteriorated by hot water or an alkaline detergent and has poor durability against the detergent.
In the method (5), a hydrophilic film composed of a resin coating agent is formed. Since the resin coating agent is deteriorated by an acidic or alkaline detergent, the hydrophilic film has a problem of poor durability against the detergent.

  The present invention has been made in view of the above problems, and has excellent hydrophilicity, excellent durability with respect to various acidic, neutral, and alkaline detergents and drugs, and high hydrophilicity. It is an object to provide a conductive film and a method for forming the same.

In order to solve the above problems, the present invention provides the following configurations.
The invention according to claim 1 is a hydrophilic film for covering and protecting a planar substrate, a double oxide composed of silicon and zirconium, an alkaline earth metal and water, or silicon oxide and zirconium. It is composed of a film containing a mixture of an oxide, an alkaline earth metal and water, and the pores of the surface layer of the film are blocked by a hydrate of an alkaline earth metal silicate. It is a hydrophilic film.
According to a second aspect of the present invention, the pores of the surface layer of the coating are a mixture of an alkaline earth metal silicate hydrate and a glycol or a surfactant, or an alkaline earth metal silicate water. The hydrophilic film according to claim 1, wherein the hydrophilic film is blocked with a compound obtained from a Japanese product and a glycol or a surfactant.
According to a third aspect of the present invention, there is provided a planar base material, a double oxide composed of silicon and zirconium, an alkaline earth metal and water, or a mixture of silicon oxide and zirconium oxide and an alkaline earth metal. A hydrophilic film forming method comprising a first step of forming a film containing water and a second step of bringing a silicate aqueous solution into contact with the film.
The invention according to claim 4 is the method for forming a hydrophilic film according to claim 3, wherein in the first step, the film contains glycols or a surfactant.
The invention according to claim 5 is characterized in that, in the second step, as the silicate aqueous solution, a solution containing glycols or a surfactant is used. It is a forming method.
According to a sixth aspect of the present invention, in the first step, the coating is formed by applying a paint containing a silicon compound, a zirconium compound, an alkaline earth metal, and water to a planar substrate. The method for forming a hydrophilic film according to claim 3, wherein the hydrophilic film is formed.
The invention according to claim 7 is the method for forming a hydrophilic film according to claim 6, wherein the paint contains a glycol or a surfactant.

According to the hydrophilic film of the present invention, a double oxide composed of silicon (Si) and zirconium (Zr), an alkaline earth metal and water, or a mixture of silicon oxide and zirconium oxide and an alkaline earth metal And a film containing water can prevent adhesion of dirt and the like due to the hydrophilicity of the film. For this reason, when a hydrophilic film | membrane is formed in a planar base material etc., it can make it difficult to adhere dirt etc. to a base material with a hydrophilic film | membrane.
Furthermore, since the pores of the surface layer of the film are blocked by a hydrate of a compound composed of alkaline earth metal ions and silicate ions, the surface layer of the film becomes dense, and an aqueous solution such as an alkaline aqueous solution or hot water is used. Is difficult to penetrate. For this reason, it has the durability outstanding with respect to various detergents, chemicals, and hot water of acid, neutrality, and alkali, and high hardness and strong film strength are obtained. Furthermore, since it is excellent in durability against various detergents and chemicals, hardness and film strength are hardly lowered, and excellent long-term stability can be obtained.

  According to the method for forming a hydrophilic film of the present invention, as a means for forming a film or a means for bringing a silicate aqueous solution into contact with the film, a known coating method, drying, or heating method can be applied. The hydrophilic membrane of the present invention can be easily formed. In addition, a coating containing a double oxide composed of silicon and zirconium and an alkaline earth metal and water, or a mixture of silicon oxide and zirconium oxide, an alkaline earth metal and water is hydrophilic. Due to the property, excellent adhesion to the substrate can be obtained, so that a hydrophilic film can be formed regardless of the material of the substrate.

Hereinafter, a hydrophilic film and a method for forming the same according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of the hydrophilic membrane of the present invention. This hydrophilic film is usually formed so as to cover the surface of a planar substrate, protects the surface of this substrate, imparts hydrophilicity to the substrate, and adheres dirt etc. to the substrate surface. It functions to make it difficult.
The coating is roughly composed of silicon (Si), zirconium (Zr), alkaline earth metal, and water.
Here, the water contained in the film is not a mere liquid water, but is contained in a solid like crystal water, and occupies a specific position in the solid by a chemical bond. . The alkaline earth metal is one or more elements selected from magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

In this film, silicon (Si) and zirconium (Zr) are contained as a double oxide composed of silicon (Si) and zirconium (Zr), or a mixture of silicon oxide and zirconium oxide.
When the film contains a double oxide composed of silicon (Si) and zirconium (Zr), an alkaline earth metal, and water, the film is represented by the following formula (I).

M _p (SiO _m ) _x (ZrO _n ) _y (H ₂ O) _q (I)

Here, m and n are values from 1 to 4, x and y are positive values that satisfy the relational expression x + y = 1, and p and q are positive values. M is an alkaline earth metal, and the general formula Mg _k1 Ca _k2 Sr _{k3 Bak 4} Ra _k5 (k1, k2, k3, k4, k5 are values of 0 or more, k1, k2, k3, k4 All of k5 are not 0.)

  When the film contains a mixture of silicon oxide and zirconium oxide, an alkaline earth metal, and water, the film is represented by the following formula (II).

_{{M p1 (SiO m) x} (H 2 O) z1 + M p2 (ZrO n) y (H 2 O) z2} (II)

Here, p1 and p2 are positive values, m and n are values of 1 to 4, x and y are positive values that satisfy the relational expression x + y = 1, and z1 and z2 are positive values. Value. M is an alkaline earth metal, and the general formula Mg _k1 Ca _k2 Sr _{k3 Bak 4} Ra _k5 (k1, k2, k3, k4, k5 are values of 0 or more, k1, k2, k3, k4 All of k5 are not 0.)
In the coating, a double oxide composed of silicon (Si) and zirconium (Zr) and a mixture of silicon oxide and zirconium oxide may be mixed at an arbitrary ratio.

In the formulas (I) and (II), the content of SiO _m in the hydrophilic film is preferably 1% by mass to 90% by mass, and more preferably 50% by mass to 70% by mass. Thereby, the hydrophilicity is improved and the durability against an alkaline solution such as an alkaline detergent can be improved.
If the SiO _m content is less than 1% by mass, sufficient hydrophilicity cannot be obtained, and if the SiO _m content is more than 90% by mass, sufficient durability cannot be obtained for an alkaline solution. It is not preferable.

The content of ZrO _n of the formula (I), (II) in, in the hydrophilic film is preferably from 1% to 90% by weight, more preferably 20% to 40% by weight. Thereby, while improving hydrophilicity, durability with respect to alkaline solutions, such as an alkaline detergent, and hot water can also be improved.
When the content of ZrO _n is less than 1% by mass, sufficient durability against an alkaline solution or hot water cannot be obtained. When the content of ZrO _n is more than 90% by mass, sufficient hydrophilicity is obtained. This is not preferable because

As a method for forming a hydrophilic film in which a silicon oxide component (SiO _m ) and a zirconium oxide component (ZrO _n ) are uniformly dispersed, for example, a method of hydrolyzing a silicon alkoxide or a zirconium alkoxide can be applied. Thereby, a hydrophilic film in which silicon oxide and zirconium oxide are mixed at a nano level, or a hydrophilic film containing a double oxide composed of silicon and zirconium having a uniform composition distribution is obtained.

The content of the alkaline earth metal (M) in the hydrophilic film is preferably 0.01% by mass to 20% by mass, whereby sufficient hydrophilicity is obtained, and it is superior to an alkaline solution such as an alkaline detergent. Durability.
When the alkaline earth metal content is less than 0.01% by mass, sufficient durability cannot be obtained with respect to the alkaline solution. Since adhesion cannot be obtained, it is not preferable.

The water content in the hydrophilic film is preferably 1% by mass to 70% by mass, and more preferably 5% by mass to 50% by mass. As described above, this water is contained in the solid like crystal water, and occupies a specific position in the solid by chemical bonding.
For this reason, when the content of water is in the above-described range, excellent hardness and mechanical strength can be obtained, and sufficient hydrophilicity can be obtained.
When the water content is less than 1% by mass, sufficient hydrophilicity cannot be obtained, and when the water content is more than 70% by mass, the hardness of the hydrophilic film is lowered, which is not preferable. .

The thickness of the hydrophilic film is preferably 0.01 μm to 5 μm, more preferably 0.1 μm to 1.0 μm. Thereby, it can be set as the hydrophilic film | membrane which has strong adhesiveness with respect to a base material with the outstanding hydrophilic property, durability, and high hardness.
In particular, in order to obtain a hydrophilic film having an excellent anti-soap adhesion effect, the thickness of the hydrophilic film is preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 1.0 μm.
When the thickness of the hydrophilic film is less than 0.01 μm, the effect of the hydrophilic film cannot be sufficiently obtained, and when the thickness of the hydrophilic film is more than 5 μm, the adhesion to the substrate is reduced. It is not preferable.

Next, the chemical structure and surface state of the hydrophilic film, which is the gist of the present invention, will be described.
In the above formulas (I) and (II), SiO _m , that is, a silicon oxide component or silicon oxide of a double oxide composed of silicon (Si) and zirconium (Zr) is an alkaline earth metal (M). It chemically reacts with water to form the chemical structure (A) shown below in the hydrophilic film.
Here, in chemical structure (A), w is a positive value.

—Si—O—M—O—Si— · wH ₂ O (A)

By alkaline earth metal (M) is contained in the SiO _m, but improved durability against an alkaline solution and hot water, such as alkaline detergent, the film strength of the hydrophilic film is in some cases lowered.
In the hydrophilic film, ZrO _n in the above formulas (I) and (II), that is, a zirconium oxide component or zirconium oxide of a double oxide composed of silicon (Si) and zirconium (Zr) is contained. has been contained, the ZrO _n is because it has excellent durability against alkaline solutions, resistance to alkaline solutions and hot water of the hydrophilic film is improved slightly.
However, the durability against alkaline solutions and hot water may still be insufficient under severe environments.

The present inventors have disclosed a film containing SiO _m , ZrO _n , alkaline earth metal, and water, that is, a double oxide composed of silicon (Si) and zirconium (Zr), an alkaline earth metal and water, or silicon. As a result of intensive studies on a film containing a mixture of oxide and zirconium oxide, an alkaline earth metal, and water, fine pores exist in the surface layer of the film, and an alkaline solution or hot water is introduced from these holes. It has been found that sufficient durability may not be obtained due to penetration, and that sufficient hardness and film strength may not be obtained due to the presence of fine pores in the surface layer.

In the hydrophilic membrane of the present invention, the pores in the surface layer are filled with the hydrate of alkaline earth metal silicate, and the pores are closed. Here, the surface layer of the coating is a portion near the surface of the coating.
Examples of the alkaline earth metal silicate include magnesium silicate (Mg ₂ SiO ₄ ), calcium silicate (CaSiO ₄ ), strontium silicate (SrSiO ₄ ), barium silicate (BaSiO ₄ ), and radium silicate (RaSiO ₄ ). These hydrates all have excellent hydrophilicity, alkali resistance, and hot water resistance.

For this reason, the pores of the surface layer of the film are closed by the hydrate of the alkaline earth metal silicate, so that the surface layer of the film becomes dense and it is difficult for an aqueous solution such as an alkaline aqueous solution or hot water to penetrate. Become.
As a result, not only hot water and alkaline solutions, but also excellent durability against acid, neutral and alkaline detergents and chemicals, and high hardness and strong film strength can be obtained. Furthermore, since it is excellent in durability against various detergents and chemicals, hardness and film strength are hardly lowered, and excellent long-term stability can be obtained.

The pores of the surface layer of the coating are a mixture of an alkaline earth silicate hydrate and a glycol or a surfactant such as polyethylene glycol, or an alkaline earth silicate hydrate and a glycol. It is preferably blocked by a compound obtained from a kind or a surfactant. Here, as a compound obtained from an alkaline earth metal silicate hydrate and a glycol or a surfactant, it is obtained by a chemical reaction between a hydroxyl group in the silicate and an oxygen atom in the glycol. Examples thereof include an insoluble metal soap produced by a reaction between a compound or an alkaline earth metal such as calcium and a hydrophilic group of a surfactant.
In the pores filled with such a compound or mixture, for example, a surfactant and an alkaline earth metal salt, or a compound obtained from glycols and silicic acid is generated, and the surface layer of the film becomes more dense, Further superior durability against hot water, various acid, neutral and alkaline detergents and chemicals can be obtained, and higher hardness and strong film strength can be obtained.

As glycols, polyethylene glycol is preferable, and the molecular weight of polyethylene glycol is preferably 200 to 20000. When the molecular weight is smaller than 200, the surface layer of the film is not sufficiently dense, and when the molecular weight is larger than 20000, the strength of the film is lowered, which is not preferable.
The content of glycols in the hydrophilic film is preferably 0.01% by mass to 5% by mass.
As the surfactant, soaps such as sodium salts of higher fatty acids and anionic surfactants are suitable. The content of the surfactant in the hydrophilic film is preferably 0.01% by mass to 5% by mass.

  In the hydrophilic film, the film represented by the above formulas (I) and (II) (also referred to as the first film) is composed of a hydrate of a compound composed of alkaline earth metal ions and silicate ions. It is preferable that the surface layer of the first film is covered with the second film so that the pores in the surface layer of the first film are blocked by the second film. By covering the first film with the second film, the entire surface layer of the hydrophilic film becomes dense, and further excellent durability, high hardness and strong film strength can be obtained.

According to the present invention, the hydrophilic film comprises a double oxide composed of silicon (Si) and zirconium (Zr), an alkaline earth metal and water, or a mixture of silicon oxide and zirconium oxide and an alkaline earth metal. And a film containing water can have an appropriate hydrophilicity and can prevent adhesion of dirt and the like. Moreover, even if dirt adheres, it becomes easy to remove dirt. For this reason, when a hydrophilic film | membrane is formed in a planar base material etc., it can make it difficult to adhere dirt etc. to a base material with a hydrophilic film | membrane.
Furthermore, the pores in the surface layer of the film are blocked by a hydrate of a compound composed of alkaline earth metal ions and silicate ions, so that various acid, neutral and alkaline detergents can be used even in harsh environments. It has excellent durability against chemicals, hot water, and high hardness.

The hydrophilic film contains one or more elements selected from alkali metals, aluminum (Al), and iron (Fe), one or more of divalent metal ions, resins, and silane coupling agents. It doesn't matter.
Examples of the alkali metal include one or more elements selected from lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).
Examples of the divalent metal ion include zinc ion (Zn ²⁺ ), copper (II) ion (Cu ²⁺ ), iron (II) ion (Fe ²⁺ ), nickel ion (Ni ²⁺ ), manganese (II) ion (Mn ²⁺ ). One or more elements selected from the group consisting of zinc ions (Zn ²⁺ ) or copper (II) ions (Cu ²⁺ ) are preferred.

In a hydrophilic film containing one or more elements selected from alkali metals, aluminum (Al), and iron (Fe) and divalent metal ions, silicon (Si) is added by containing these elements and metal ions. ), Zirconium (Zr), oxygen (O), alkaline earth metal, and water will change. For this reason, properties, such as hardness of a hydrophilic film | membrane, can be adjusted by adjusting content of the said element and metal ion.
In addition, about iron (Fe), metal ions of valence other than bivalence can be used, and the same effect is acquired.

The content of the alkali metal in the hydrophilic film is preferably 0.01% by mass to 1% by mass, and thereby hydrophilicity can be improved.
When the content of alkali metal is less than 0.01% by mass, almost no effect due to the inclusion of the alkali metal is observed, and when the content of alkali metal is greater than 1% by mass, Since durability falls, it is not preferable.

The content of aluminum (Al) in the hydrophilic film is preferably 0.1% by mass to 10% by mass, which can improve durability against an alkaline solution.
When the content of aluminum (Al) is less than 0.1% by mass, almost no effect due to the inclusion of aluminum (Al) is observed, and the content of aluminum (Al) is more than 10%. In this case, the hydrophilicity is lowered, which is not preferable.

The content of the divalent metal ion in the hydrophilic film is preferably 0.1% by mass to 10% by mass, and this can improve the hardness of the hydrophilic film.
When the content of the divalent metal ion is less than 0.1% by mass, the effect due to the inclusion of the divalent metal ion is hardly observed, and the content of the divalent metal ion is 10%. If it is more than the upper limit, the hardness of the hydrophilic film is lowered, which is not preferable.

Although resin is not specifically limited, For example, an acrylic resin, a urethane resin, a melamine resin, an epoxy resin, a silicone resin, a fluororesin etc. are mentioned, The water-type which can be mixed with water is suitable.
Usually, since resin can improve the adhesiveness with respect to the base-material surface of the inorganic component in a hydrophilic film | membrane, the adhesiveness with respect to a base material can be improved because resin was contained in the hydrophilic film | membrane.

As said resin, an acrylic resin is preferable, and thereby the adhesiveness with respect to a base material and the softness | flexibility of a hydrophilic film | membrane can be improved.
The acrylic resin is not particularly limited, for example, polyacrylic acid which is a polymer of acrylic acid, polymethacrylic acid which is a polymer of methacrylic acid, a polymer of a derivative of acrylic acid, a polymer of a derivative of methacrylic acid, Examples thereof include two or more kinds of copolymers selected from acrylic acid, methacrylic acid, derivatives of acrylic acid, and derivatives of methacrylic acid.

The silane coupling agent is an organic silane compound represented by a general formula R ¹ Si (OR) ₃ (R ¹ is an organic substituent, and OR is a hydrolyzable functional group). Examples of the silane coupling agent include trimethoxyphenylsilane, trimethoxymethylsilane, vinyltriethoxysilane, 3-methacrylopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. Preferably, this can improve the adhesion to the substrate.

In the hydrophilic film containing the silane coupling agent, the adhesion to the substrate can be improved.
In particular, the silane coupling agent has an organic functional group and a hydrolyzable group in one molecule, and has a property of hydrolyzing and chemically bonding an organic component such as a resin and an inorganic component.
For this reason, especially the adhesiveness with respect to a resin base material can be improved, and the physical strength of a hydrophilic film | membrane, water resistance, and the adhesiveness with respect to a base material can be improved significantly.
When the hydrophilic film contains a silane coupling agent together with the resin, the silane coupling agent improves not only the adhesion between the base material and the inorganic component but also the adhesion between the added resin and the inorganic component. Therefore, the durability of the entire hydrophilic film can be enhanced.

The content of the resin or the silane coupling agent in the hydrophilic film is preferably 1% by mass or more and 10% by mass or less, thereby improving the adhesion to the resin substrate.
When the content of the resin or silane coupling agent in the hydrophilic film is less than 1% by mass, almost no effect due to the inclusion of the resin or silane coupling agent is observed, and the content is more than 10% by mass. When the amount is large, the hydrophilicity is lowered, which is not preferable.

  Further, the hydrophilic film may contain silver (Ag). By containing silver (Ag), antibacterial properties can be imparted to the hydrophilic film.

Next, the formation method of the hydrophilic film | membrane of this invention is demonstrated.
As a first step, a double oxide composed of silicon and zirconium and an alkaline earth metal and water, or a mixture of silicon oxide and zirconium oxide and an alkaline earth metal and water are applied to a planar substrate. Form a coating containing it.
The substrate is not particularly limited, inorganic materials such as glass, ceramics, pots, concrete, stones, metal materials such as iron, stainless steel, aluminum, gold, silver, titanium, various platings, organic materials such as plastics and fibers, etc. And having a surface such as a curved surface, a flat surface, and an uneven surface.

Examples of the method for forming a film on the base material include a method of applying a paint containing a silicon compound, a zirconium compound, an alkaline earth metal, and water to the base material. A method for forming a film using this paint will be described below.
First, a paint containing a silicon compound, a zirconium compound, an alkaline earth metal, and water is prepared.
The silicon compound is preferably a water-soluble salt such as alkali silicate, silicon alkoxide such as colloidal silica (silica sol), tetraethoxysilane, or tetramethoxysilane, and is inexpensive and easy to handle.
In particular, ultrafine silicon oxide obtained by hydrolyzing silicon alkoxide is more preferable, and thereby a film having excellent strength can be formed.
The content of the silicon compound in the paint is preferably 0.1% by mass to 9% by mass in terms of oxide (content calculated assuming that the silicon compound is all silicon oxide).

As the zirconium compound, water-soluble salts such as zirconium oxychloride and zirconium oxynitrate, zirconium alkoxides such as tetrapropoxyzirconium and tetrabutoxyzirconium, hydrolysates thereof, and zirconia sols are preferable.
In particular, an ultrafine zirconium oxide obtained by hydrolyzing zirconium alkoxide is more preferable, whereby a film having excellent strength can be formed.
The content of the zirconium compound in the paint is preferably 0.1% by mass to 9% by mass in terms of oxide (content calculated assuming that all zirconium compounds are zirconium oxide).

  The mass ratio of the zirconium compound to the silicon compound in the paint is preferably 1/10 to 10/1 in terms of oxide (content calculated assuming that all silicon compounds are silicon oxides and all zirconium compounds are zirconium oxides). More preferably, it is 2/7 to 4/5. Thus, the formed hydrophilic film has moderate hydrophilicity and durability, and can prevent adhesion of dirt and the like.

The alkaline earth metal is one or more elements selected from magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). Is contained as a single ion or a compound such as a salt.
Examples of compounds containing alkaline earth metals include water-soluble salts such as alkaline earth metal nitrates, chlorides, and organic acid salts, and other elements contained in paints such as calcium silicate, that is, the present invention. It may be a compound containing other elements (silicon (Si), zirconium (Zr), etc.) constituting the hydrophilic film formed.

The content of the alkaline earth metal in the paint is preferably 10 ppm to 2% by mass in terms of ions (content calculated assuming that all the alkaline earth metals are present as single ions).
When the content of alkaline earth metal is less than 10 ppm, a film having sufficient durability against an alkaline solution cannot be formed. When the content is more than 2% by mass, sufficient adhesion to a substrate is achieved. This is not preferable because a film having s cannot be formed.

The paint may contain glycols. After forming a film using this paint, the pores in the surface layer of the film can be almost completely closed by bringing the silicate aqueous solution into contact with the film surface in a second step described later.
As glycols, polyethylene glycol is preferable, and the pores can be closed in a short time. The molecular weight of polyethylene glycol is preferably 200 to 20000, which makes it easier to close the pores.
The content of glycols in the coating is preferably 0.01% by mass to 5% by mass, which closes the hole almost completely and improves the slipperiness of the hydrophilic film surface, making it difficult to be damaged.

  Although water is contained as a solvent in the paint, the content of water is preferably 1% by mass to 90% by mass, whereby a paint component containing a solid content (silicon compound, zirconium compound, alkaline earth metal) ) Can be carried out.

In addition to water, the solvent preferably contains an organic solvent having excellent compatibility with water, such as alcohols and ketones.
Thereby, the spreading of the coating material on the substrate surface is improved, and uneven coating can be eliminated when the coating material is applied to the substrate surface.
The solid content concentration in the paint is not particularly limited, but is preferably 0.1% by mass to 10% by mass. Thereby, it becomes easy to form a film having a desired film thickness on a substrate having an appropriate viscosity by a coating method. Here, the solid content in the paint is a value calculated from the ignition residue, and can be adjusted by adjusting the content of water or a solvent such as an organic solvent in the paint.

The pH (hydrogen ion concentration index) of the paint is preferably 2 or less, thereby suppressing the hydration reaction in the paint and preventing the paint from solidifying before being applied to the substrate.
In order to adjust the pH of the paint, it is preferable that an acid is contained in the paint. A volatile acid is preferable as the acid, and examples thereof include nitric acid, hydrochloric acid, and acetic acid.
The content of the acid in the paint is preferably 0.1% by mass to 10% by mass, whereby the hydration reaction can be suppressed, and the quality of the paint is difficult to change.

The paint may contain one or more elements selected from alkali metals, aluminum (Al), iron (Fe), divalent metal ions, resins, and silane coupling agents. .
Examples of the alkali metal include one or more elements selected from lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). The alkali metal, aluminum (Al), and iron (Fe) are contained in the paint as a single ion or a compound such as a salt.
Examples of compounds containing alkali metals include water-soluble salts such as alkali metal nitrates, chlorides, and organic acid salts, and other elements contained in paints such as lithium silicate and lithium zirconate. A compound containing other elements (silicon (Si), zirconium (Zr), etc.) constituting the hydrophilic film formed in this manner is preferable.
The content of the alkali metal in the paint is preferably 0.01% by mass to 1% by mass in terms of ions (content calculated assuming that all alkali metals are present as single ions), and thus more excellent. It is possible to form a highly hydrophilic film.

As the compound containing aluminum (Al), a water-soluble salt such as aluminum nitrate and chloride, an alkoxide such as aluminum isopropoxide or a hydrolyzate thereof, and an alumina sol are preferable. A film having excellent durability can be formed.
The content of aluminum (Al) in the coating is preferably 0.01% by mass to 1% by mass in terms of ions (content calculated assuming that all aluminum is present as a single ion).

Examples of the divalent metal ion include zinc ion (Zn ²⁺ ), copper (II) ion (Cu ²⁺ ), iron (II) ion (Fe ²⁺ ), nickel ion (Ni ²⁺ ), manganese (II) ion (Mn ²⁺ ). One or more elements selected from the group consisting of zinc ions (Zn ²⁺ ) or copper (II) ions (Cu ²⁺ ) are preferred.
This divalent metal ion is contained in the paint as a single ion or a compound such as a salt. As the compound containing a divalent metal ion, water-soluble salts such as nitrates and chlorides are suitable.
The content of the divalent metal ions in the coating is preferably 0.01% by mass to 1% by mass, whereby a film excellent in durability against an alkaline solution or hot water can be formed.

By using a paint containing one or more elements selected from alkali metals, aluminum (Al), and iron (Fe) and divalent metal ions, a composite composed of silicon and zirconium is formed when the coating is formed. A network structure composed of an oxide, an alkaline earth metal ion, and water is cross-linked by these elements and metal ions, whereby the hardness of the hydrophilic film can be improved.
In addition, about iron (Fe), metal ions of valence other than bivalence can be used, and the same effect is acquired.

The resin is not particularly limited, and examples thereof include an acrylic resin, a urethane resin, a melamine resin, an epoxy resin, a silicone resin, and a fluorine resin, and an aqueous type that can be mixed with water is preferable.
Since the resin can improve the adhesion of the inorganic component in the coating material to the substrate surface, a coating film having excellent adhesion to the substrate can be formed by using the coating material containing this resin.

As said resin, an acrylic resin is preferable, and thereby, the adhesiveness with a base material can be improved and the film can be given flexibility.
The acrylic resin is not particularly limited, for example, polyacrylic acid which is a polymer of acrylic acid, polymethacrylic acid which is a polymer of methacrylic acid, a polymer of a derivative of acrylic acid, a polymer of a derivative of methacrylic acid, Examples thereof include two or more kinds of copolymers selected from acrylic acid, methacrylic acid, derivatives of acrylic acid, and derivatives of methacrylic acid.
The content of the acrylic resin in the paint is preferably 0.1% by mass to 1% by mass, and thereby a film with excellent adhesion and flexibility can be formed.

The silane coupling agent is an organic silane compound represented by a general formula R ¹ Si (OR) ₃ (R ¹ is an organic substituent, and OR is a hydrolyzable functional group). Examples of the silane coupling agent include trimethoxyphenylsilane, trimethoxymethylsilane, vinyltriethoxysilane, 3-methacrylopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. Preferably, this can improve the adhesion to the substrate.

By using a paint containing a silane coupling agent, it is possible to form a hydrophilic film having excellent adhesion to the substrate.
In particular, a silane coupling agent has an organic functional group and a hydrolyzable group in one molecule, and has a property of hydrolyzing and chemically bonding an organic material such as a resin and an inorganic material. For this reason, it is preferable to use a paint containing a silane coupling agent together with a resin, whereby the physical strength and water resistance of the hydrophilic film and the adhesion to the substrate can be greatly improved.
The sum of the content of the resin and the silane coupling agent in the paint is preferably 1% by mass or more and 10% by mass or less, which can improve the adhesion to the substrate.

In addition, the mass ratio (percentage) of the alkali component in the coating with respect to the sum of the silicon compound and the zirconium compound is calculated by the content calculated as an oxide (the silicon compound, the zirconium compound, and the alkali component are each oxides). Value) is preferably 0.1% by mass to 5% by mass. Thereby, the durability with respect to the alkaline solution is not remarkably lowered and a film having further excellent hydrophilicity can be formed.
Here, the alkali component is a compound containing an alkali metal, specifically, a lithium salt, a sodium salt, a potassium salt, or the like.

The mass ratio (percentage) of the compound containing aluminum (Al) with respect to the sum of the silicon compound and the zirconium compound is an oxide equivalent (a silicon compound, a zirconium compound, and a compound containing aluminum (Al) are oxides). Value calculated by the content calculated as 0.1) to 5% by mass is preferable. Thereby, the film which has the further outstanding durability with respect to an alkaline solution can be formed.
In addition, the mass ratio (percentage) of the divalent metal ion to the sum of the silicon compound and the zirconium compound is calculated in terms of oxide (the silicon compound, the zirconium compound, and the divalent metal ion are each calculated as an oxide) The value calculated by the amount) is preferably 0.1% by mass to 5% by mass. Thereby, the film which has the further outstanding durability with respect to an alkaline solution can be formed.

Such a paint is obtained by a method in which each component is weighed in a predetermined amount and mixed with a solvent such as water or alcohol.
When mixing each component with a solvent such as water or an organic solvent such as alcohol, an acid such as nitric acid, hydrochloric acid, acetic acid or sulfuric acid is added to adjust the pH appropriately so that precipitation or condensation does not occur. It is preferable to mix while adjusting the water content.
As the organic solvent such as alcohol, alcohols such as methanol, ethanol and isopropyl alcohol, ketones and cellosolves are suitable.

After the coating material adjusted in this way is applied to a planar substrate, a film is obtained by drying or heating as necessary.
The method for applying the paint is not particularly limited, and known methods such as a dipping method, a spray method, and a brush coating method can be applied.
The drying and heating methods are not particularly limited, and known methods such as natural drying and methods using heating means such as a dryer can be applied.

When the paint applied to the planar substrate is dried or heated, the acid in the paint evaporates and the pH rises. As the pH of the paint rises, a hydration reaction occurs in the paint. By this hydration reaction, the silicon compound and the zirconium compound are double oxides composed of silicon (Si) and zirconium (Zr), silicon oxide, One or more hydrates selected from hydrates containing zirconium oxide are obtained.
Here, the hydration reaction is a reaction that occurs when the cement hardens. Since water is taken into the solid like crystallization water by the hydration reaction, excellent hydrophilicity can be obtained.
As an example, a reaction in which silicon oxide becomes a hydrate by a hydration reaction is shown in the following formula (III).

-Si-OH + Ca (OH) ₂ + HO-Si-
→ -Si-O-Ca-O -Si- · 2H 2 O (III)

Conventionally, a method of forming a silica film as a hydrophilic film by a sol-gel reaction has been disclosed. In this method, a silicon compound is hydrolyzed using an acid as a catalyst and then cured by a dehydration condensation reaction to form a silica film. It was.
As an example, the following formula (IV) shows a reaction in which a hydrolyzate of silicon alkoxide or colloidal silica is cured by a dehydration condensation reaction to form a silica film.

-Si-OH + HO-Si- → -Si-O-Si- + H 2 O ↑ (IV)

In the conventional method, since some hydroxyl groups (OH groups) remain unreacted, the silica film of the obtained hydrophilic film exhibits hydrophilicity. However, there is a problem that the Si—O bond is weak to alkaline solution or hot water.
In the present invention, the conventional method is completely different from the conventional method in terms of the entry and exit of water, whereby a film with improved durability against alkaline solutions and hot water can be formed.

  The drying temperature or heating temperature is preferably 40 ° C. to 300 ° C., whereby the acid is likely to volatilize, the pH rises due to the volatilization of this acid, the hydration reaction is promoted, and the hydrophilic film is easily cured in a short time. Can be formed.

Next, as a second step, a silicate aqueous solution is brought into contact with the formed film to form a hydrophilic film.
As the silicate, for example, a water-soluble salt such as lithium silicate, sodium silicate, and potassium silicate is preferable, and thereby the hydrophilicity and hardness of the hydrophilic film can be improved.
The concentration of the silicate in the silicate aqueous solution is preferably 0.01% by mass to 20% by mass, and thereby the hydrophilicity and hardness can be further improved.
When the silicate concentration is lower than 0.01% by mass, a sufficient effect cannot be obtained. When the silicate concentration is higher than 20% by mass, a large amount of unreacted silicate ions remain. It is not preferable.

The method of bringing the silicate aqueous solution into contact with the film is not particularly limited. For example, the method of immersing the film in a silicate aqueous solution, the method of spraying the silicate aqueous solution on the film, the method of applying the silicate aqueous solution to the film, silicate A known method such as a method of wiping the surface of the film using a sponge or cloth soaked with an aqueous solution can be applied.
In the method of immersing the film in an aqueous silicate solution, the silicate aqueous solution can be brought into uniform contact with the surface of the film, and the silicate hardly becomes smeared on the film surface after drying, thereby improving the yield.

In the first step, when a film is formed by a hydration reaction, there are water gaps, so that fine pores are formed in the surface layer of the film. Alkaline earth metal ions (M ²⁺ ) such as unreacted calcium ions are present in the pores.
When an aqueous silicate solution is brought into contact with this film, silicate ions (SiO ₄ ⁴⁻ ) in the aqueous silicate solution enter the pores, and in the pores, alkaline earth metal as shown by the following formula (V) Silicate hydrate (MSiO ₄ .H ₂ O) is formed. Then, the pores are closed by the alkaline earth metal silicate hydrate, the surface layer of the film is dense, and the aqueous alkaline solution or hot water is less likely to soak.

SiO ₄ ⁴⁻ + 2M ²⁺ + H ₂ O → MSiO ₄ .H ₂ O (V)

In the second step, it is preferable to use a solution containing an aqueous silicate solution, glycols or a surfactant. Since glycols or surfactants are as described above, description thereof is omitted.
As for the density | concentration of glycols or surfactant in silicate aqueous solution, 0.1 mass%-10 mass% are preferable.
When the concentration of glycols or surfactant is lower than 0.1% by mass, a sufficient effect cannot be obtained, and when the concentration of glycols or surfactant is higher than 10% by mass, unreacted glycols Alternatively, a large amount of the surfactant remains, which is not preferable.

By using a silicate aqueous solution containing a glycol or a surfactant, the pores of the surface layer of the film are formed by the silicate hydrate of the alkaline earth metal and the glycol or the surfactant. Or a compound obtained from an alkaline earth metal silicate hydrate and a glycol or a surfactant.
As a result, the surface layer of the film becomes denser, and more excellent durability against hot water, various acid, neutral and alkaline detergents and drugs can be obtained, and higher hardness can be obtained.

In the first step, a glycol or a surfactant may be previously contained using a paint containing a glycol or a surfactant.
Thereby, it can be set as the state in which glycols or surfactant existed in the hole of the surface layer of a film, and in the 2nd process, the hole of the surface layer of a film was made of alkaline earth metal silicate. It can be blocked by a compound obtained from a mixture of a hydrate and a glycol or a surfactant, or a hydrate of an alkaline earth metal silicate and a glycol or a surfactant.

According to this method for forming a hydrophilic film, known coating methods, drying and heating methods can be applied, and the hydrophilic film of the present invention can be easily formed on a planar substrate. In addition, because it has excellent adhesion due to hydrophilicity, it can form a hydrophilic film regardless of the material of the base material. For example, inorganic materials such as glass, ceramics, pots, concrete, stones, iron, stainless steel, aluminum, gold It is possible to form a hydrophilic film on a planar substrate made of various materials such as metal materials such as silver, titanium and various plating, and organic materials such as plastic and textile products.
For this reason, the present invention is applied to various products having a planar base material part that needs to be protected so as to prevent adhesion of dirt such as water scale and to prevent damage such as kitchen products, bathroom products, and washing machines. Can be formed. In particular, when a hydrophilic film is formed on the washing machine's washing tub, wash basin, bathtub, drain hole periphery, flush fittings, pipes, etc. as a base material, it prevents not only oil stains but also soap scum. Moreover, even if dirt is attached, it can be removed, which is preferable.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this.
[Example 1]
As a first step, 3 parts by mass of ethyl silicate as a silicon compound, 2 parts by mass of zirconium butoxide as a zirconium compound, 1 part by mass of calcium nitrate as a compound containing an alkaline earth metal, 53 parts by mass of water, and isopropyl as a solvent other than water 40 parts by mass of alcohol and 1 part by mass of nitric acid as an acid for pH adjustment were mixed to prepare a coating material for film formation.
This paint was applied to the stainless steel surface of the stainless steel sink using a spray so that the thickness became 0.2 μm. And hot air was sprayed and it dried at 180 degreeC, and the membrane | film | coat was formed.
Next, as a second step, a sodium silicate aqueous solution (silicate aqueous solution) having a concentration of 1% by mass was applied to the film, and then washed with water to form a hydrophilic film. A stainless steel sink with a hydrophilic treatment was thus obtained.

[Comparative Example 1]
A hydrophilic film was formed on the stainless steel surface of the stainless steel sink by the same method as in Example 1 except that the second step was not performed.

[Example 2]
As a first step, 5 parts by mass of colloidal silica as a silicon compound, 2 parts by mass of zirconium butoxide as a zirconium compound, 0.01 parts by mass of calcium nitrate as a compound containing an alkaline earth metal, and polyethylene glycol (molecular weight 400) as glycols 0.5 parts by mass, 10 parts by mass of water, 82 parts by mass of isopropyl alcohol as a solvent other than water, and 0.5 parts by mass of acetic acid as an acid for pH adjustment were mixed to prepare a coating material for film formation.
This paint was applied to an ABS resin plate using a bar coater so as to have a thickness of 0.05 μm. And hot air was sprayed and it dried at 80 degreeC, and formed the membrane | film | coat.
Next, as a second step, a mixture of a lithium silicate aqueous solution (silicate aqueous solution) having a concentration of 0.1% by mass and sodium alkylbenzene sulfonate (surfactant aqueous solution) is used. After immersing the ABS resin plate on which was formed, drained and naturally dried to form a hydrophilic film. The ABS resin board by which the hydrophilic process was carried out by the above was obtained.

[Comparative Example 2]
A hydrophilic film was formed on the ABS resin plate in the same manner as in Example 2 except that polyethylene glycol was not used in the first step and the second step was not performed.

[Example 3]
As a first step, as a silicon compound, 4 parts by mass of ethyl silicate and 5 parts by mass of colloidal silica, 1 part by mass of zirconyl nitrate as a zirconium compound, 1 part by mass of calcium nitrate as a compound containing an alkaline earth metal, and 50 parts by mass of water Mixing 38 parts by mass of isopropyl alcohol as a solvent other than water, 1 part by mass of polyethylene glycol (molecular weight 400) as a glycol, and 0.01 parts by mass of sodium alkylbenzene sulfonate as a surfactant produce a coating composition for film formation. did.
This paint was applied to a glass plate by a dipping method so as to have a thickness of 0.2 μm. And it was made to dry at 400 degreeC and the membrane | film | coat was formed.
Next, as a second step, a silicate aqueous solution containing a glycol having a sodium silicate concentration of 10% by mass and a polyethylene glycol (molecular weight 20000) concentration of 3% by mass and sodium alkylbenzenesulfonate is used. The aqueous salt solution was showered on the film and then washed with water to form a hydrophilic film. The glass plate by which the hydrophilic process was carried out was obtained by the above.

[Comparative Example 3]
A hydrophilic film was formed on the glass plate in the same manner as in Example 3 except that polyethylene glycol was not used in the first step and the second step was not performed.

The contact angle of the obtained hydrophilic film was measured by a contact angle meter method, and the hydrophilicity of the hydrophilic film was evaluated.
In addition, after immersing the hydrophilic film in a sodium hydroxide aqueous solution having a concentration of 5% by mass at room temperature for 30 days while observing the progress, the presence or absence of the hydrophilic film is observed, and the hydrophilic film is applied to the alkaline solution. Durability was evaluated.
After immersing the hydrophilic film in hot water at 98 ° C. for 30 days, the presence or absence of the hydrophilic film was observed to evaluate the durability of the hydrophilic film against hot water.
Moreover, the pencil hardness of the hydrophilic film was measured by JIS method to evaluate the hardness of the hydrophilic film.
The measurement results are shown in Table 1 below.

The contact angle of the hydrophilic film formed on the base material is very small compared to the contact angle of the base material of the stainless steel surface, ABS resin plate, and glass plate where the hydrophilic film is not formed. It was found that the hydrophilicity is remarkably improved by the formation.
It was found that the hydrophilic films obtained in Examples 1 to 3 all had excellent durability against alkaline solutions and hot water. In contrast, in the hydrophilic films obtained in Comparative Examples 1 to 3, the immersion time disappeared within 30 days.
Further, when comparing hydrophilic films formed on the same base material, it was found that a hydrophilic film having higher hardness can be formed by bringing a silicate aqueous solution into contact with the film as the second step.

In the second step, the silicate aqueous solution is brought into contact with the coating to form an alkaline earth silicate hydrate in the pores of the surface layer of the coating. The pores are blocked by the object, the surface layer of the film is dense, and the aqueous alkali solution or hot water is difficult to penetrate.
Thereby, it was thought that the outstanding durability with respect to alkaline solution and hot water was acquired, and high hardness was acquired.

  The hydrophilic membrane of the present invention needs to be protected so that it does not adhere to dirt such as water stains as in kitchen products, bathroom products, washing machines, etc. The present invention can be applied to various products having a planar substrate part having a certain shape. In particular, when the hydrophilic film of the present invention is formed on a washing tub, a wash basin, a bathtub, a drain hole, a flush fitting, a pipe, etc. of a washing machine, it can prevent not only oil stains but also soap scum. Therefore, it can be suitably applied.

Claims (7)

In a hydrophilic film for covering and protecting a planar substrate,
A double oxide composed of silicon and zirconium and an alkaline earth metal and water, or a mixture of silicon oxide and zirconium oxide, a film containing alkaline earth metal and water,
A hydrophilic membrane, wherein the pores of the surface layer of the membrane are closed with an alkaline earth metal silicate hydrate.   The pores of the surface layer of the coating are a mixture of an alkaline earth metal silicate hydrate and a glycol or a surfactant, or an alkaline earth metal silicate hydrate and a glycol or an interface. The hydrophilic film according to claim 1, wherein the hydrophilic film is blocked with a compound obtained from an active agent. A film containing a double oxide composed of silicon and zirconium and an alkaline earth metal and water, or a mixture of silicon oxide and zirconium oxide, an alkaline earth metal and water is formed on a planar substrate. The first step,
A method for forming a hydrophilic film, comprising a second step of bringing a silicate aqueous solution into contact with the film.   The method for forming a hydrophilic film according to claim 3, wherein in the first step, the film contains a glycol or a surfactant.   5. The method for forming a hydrophilic film according to claim 3, wherein in the second step, a solution containing glycols or a surfactant is used as the silicate aqueous solution.   6. In the first step, a coating containing a silicon compound, a zirconium compound, an alkaline earth metal and water is applied to a planar substrate to form the film. The method for forming a hydrophilic film according to any one of the above.   The method for forming a hydrophilic film according to claim 6, wherein a paint containing glycols or a surfactant is used as the paint.