JP2011000500A - Method of preventing adhesion of scale to surface of product and scale adhesion preventive article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of preventing adhesion of scale to the surface of products and a scale adhesion preventive article which maintain cleanliness without possibility of adhesion of scale and thus retain a scale adhesion preventing effect for a long period, require little time and effort of cleaning, achieve water saving and also prevent fouling and damage.SOLUTION: The method of preventing adhesion of scale to the surface of products is for preventing adhesion of scale to the surface of products having a coating film which is formed at least in an area(s) of the surface of a substrate to which scale possibly adheres and contains one or more oxides selected from zirconium oxide, hafnium oxide and rare earth oxides. When scale adheres to the surface of the coating film, the scale is removed with an aqueous solution containing one or more agents selected from carboxylic acids, carboxylates and chelating agents.

Description

  The present invention relates to a method for preventing the adhesion of scale on a surface of an article and an article for preventing the adhesion of scale, and in particular, when scale adheres to the surface of the article, the scale may be easily removed by removing the scale easily. In addition, there is almost no need for cleaning, and it is possible to save water, and a method for preventing water from adhering to the surface of the article. It is about.

Contamination due to adhesion of water stains on sanitary ware, mirrors, stainless steel sinks, etc. is recognized in all places where conditions such as toilets, washrooms, kitchens, vehicle windows, bathrooms, etc. meet the conditions for water to adhere and dry. Scale is a substance in which inorganic components dissolved in water are precipitated as the water evaporates, and has a property of solidifying so that it cannot be removed, especially when left for a long period of time. .
If the scale which has been solidified in this way is forcibly removed using chemicals or abrasives, there is a disadvantage that the product itself may be damaged.
Therefore, conventionally, for the purpose of preventing the adhesion of scale, a scale adhesion preventing product in which a hydrophilic coating film or a water-repellent coating film is formed on the surface of a substrate has been proposed.

For example, as an anti-scaled product in which a hydrophilic coating film is formed on the surface of a substrate, a hydrophilic film in which a lithium-containing siliceous film contains a copolymer containing polyacrylic acid or a polyacrylic acid monomer is used. There has been proposed a scale adhesion prevention product that improves adhesion between the hydrophilic film and the surface of the substrate by forming on the surface (Patent Documents 1 to 3).
Further, a scale adhesion prevention product has been proposed in which a water-repellent coating film is formed on a surface of a glaze layer of a glazed product such as sanitary ware by applying a silicone resin or a fluororesin and cured (Patent Document 4).

  On the other hand, a cleaning agent for the purpose of removing solidified scale is commercially available. For example, acid detergents such as acid detergents and weak acid detergents are intended to decompose and remove scales and urine stones. Among neutral detergents, neutral detergents containing a chelating agent are intended to decompose and remove scale.

JP 2003-301273 A JP 2003-299606 A JP 2002-302737 A International Publication No. 2001/044452 Pamphlet

However, the above-described conventional scale adhesion prevention product has the following problems.
That is, in the conventional anti-scaled product with a hydrophilic coating film formed, water spreads thinly on the coating film, so that it is very inconspicuous even if scale deposits on the coating film by drying. However, if such a state is left for a long period of time, if wetting and drying are repeated on this coating film, the inconspicuous scale will increase in thickness, and it will still be firmly attached and cannot be removed. There was a problem that it was.

  On the other hand, in the conventional anti-scaled product formed with a water-repellent coating film, water becomes polka dots due to the surface tension on the coating film, and is difficult to adhere to the coating film. In particular, when the coating film is inclined, the polka dot rolls down along the inclined surface of the coating film, and it is difficult for the scale to adhere to the coating film, and as a result, the scale is prevented. However, when the coating film is horizontal, the polka dots remain on the coating film, and when the water evaporates as it is, the traces of the polka dots become scaled and the scale becomes remarkably noticeable. If this state is left for a long period of time, the generation and drying of polka dots are repeated, whereby the scale adheres firmly and increases its thickness, which again cannot be removed.

In addition, the adhesion between the water-repellent coating film and the substrate is weaker than that of the hydrophilic coating film, and therefore there is a problem that it is impossible to obtain a long-term scale adhesion prevention effect.
Furthermore, when the water-repellent coating film is applied to sanitary ware such as a filth tank or a toilet, water does not spread over the entire surface of the sanitary ware, which causes a problem that the filth remains unwashed. .

In addition, conventional cleaning agents for removing scales are not sufficient because they cannot sufficiently remove scales.
For example, the acid or chelating agent in the cleaning agent can dissolve the calcium component and magnesium component in scale, but cannot dissolve the silica component. Since this silica component is the same as the surface glaze of sanitary ware, glass, and stainless steel, if scale containing silica adheres, the scale will be strongly chemically bonded and can no longer be removed by cleaning agents. Is possible.

Even if the cleaning agent is allowed to flow into the washing water in small amounts, the resulting scale is strongly adhered to the surface of the sanitary ware because the silica component of the scale and the silica in the glaze on the surface of the sanitary ware are strong. There was a problem that it was fixed and the prevention of scale adhesion could not be exhibited sufficiently.
In addition, in resin toilets that automatically supply neutral detergent to the wash water, a certain effect can be obtained to prevent the adhesion of scale, but the problem of poor removal of filth and the resin surface However, there was a problem that it was easily damaged compared with sanitary ware.

  The present invention has been made in order to solve the above-described problem, and there is no possibility that scale adheres and it is possible to maintain cleanliness, and therefore, the effect of preventing scale adhesion is maintained for a long period of time. Furthermore, it is an object of the present invention to provide a method for preventing the adhesion of scales on a surface of an article and an article for preventing the adhesion of scales, which require almost no labor for cleaning, can save water, and are hardly damaged or damaged.

  As a result of intensive studies to solve the above problems, the present inventors have selected from the group of zirconium oxide, hafnium oxide, and rare earth oxide in at least a region of the surface of the substrate where dirt may adhere. In the case where an article formed with a film containing one or more kinds is used, and the scale adheres to the surface of the film, the scale is selected from the group of carboxylic acid, carboxylate, and chelating agent. If it is removed with an aqueous solution containing one or more kinds, the scale can be prevented from sticking, and the effect of preventing scale adhesion can be maintained for a long period of time. It has been found that there is no need for periodic care and that dirt and scratches are hardly attached, and the present invention has been completed.

  That is, the method for preventing scale adhesion on the surface of an article of the present invention is one or two selected from the group consisting of zirconium oxide, hafnium oxide, and rare earth oxide in at least a region where scale may adhere to the surface of the substrate. A method for preventing scale from adhering to the surface of an article on which a film comprising the above is formed, and when the scale adheres to the surface of the film, the scale is treated with carboxylic acid, carboxylate, chelating agent. It removes in the aqueous solution which contains 1 type, or 2 or more types selected from the group of these.

It is preferable that the coating further contains phosphorus.
The content of one or more selected from the group consisting of the zirconium oxide, the hafnium oxide, and the rare earth oxide in the coating is preferably 50% by mass or more.

  The scale adhesion preventing article of the present invention contains at least one type selected from the group consisting of zirconium oxide, hafnium oxide, and rare earth oxide in a region where scale may adhere to the surface of the substrate. 1 or 2 selected from the group consisting of a carboxylic acid, a carboxylate and a chelating agent when the scale adheres to the surface of the coating. It is characterized by comprising scale removal means for removing using an aqueous solution containing the above.

It is preferable that the coating further contains phosphorus.
The content of one or more selected from the group consisting of the zirconium oxide, the hafnium oxide, and the rare earth oxide in the coating is preferably 50% by mass or more.

  According to the method for preventing scale adhesion on the article surface of the present invention, when scale adheres to the surface of a coating film containing one or more selected from the group consisting of zirconium oxide, hafnium oxide, and rare earth oxides. The scale is removed with an aqueous solution containing one or more selected from the group consisting of carboxylic acid, carboxylate, and chelating agent. In combination with this, it is possible to maintain an excellent anti-scale adhesion effect for a long period of time, and there is almost no scale deposit on the surface of the coating without care.

Since the scale adhering to the surface of the coating can be easily removed with the above aqueous solution, there is no need to use a large amount of running water as in the prior art, and no strong acid, strong alkali, or abrasive is required. , Can save water, and the environmental load is small.
Furthermore, since no maintenance is required, it is possible to reduce the labor of cleaning and the cost of maintenance, which is economical.

  According to the scale adhesion preventing article of the present invention, when scale adheres to the surface of the coating film containing one or more selected from the group consisting of zirconium oxide, hafnium oxide and rare earth oxide, Is provided with a scale removing means for removing water using an aqueous solution containing one or more selected from the group consisting of carboxylic acid, carboxylate and chelating agent. Using the aqueous solution, the scale adhering to the surface of the coating can be removed quickly and sufficiently. Therefore, the effect of preventing adhesion of scale can be maintained for a long time.

Since the scale adhering to the surface of the coating can be easily removed with the above aqueous solution, there is no need to use a large amount of running water as in the prior art, and no strong acid, strong alkali, or abrasive is required. , Can save water, and the environmental load is small.
Furthermore, since no maintenance is required, it is possible to reduce the labor of cleaning and the cost of maintenance, which is economical.

An embodiment for carrying out the method for preventing the adhesion of scale on the surface of an article and the article for preventing the adhesion of scale according to the present invention will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.
In this embodiment, first, a scale adhesion preventing article will be described, and then a scale adhesion preventing method for the surface of the scale adhesion preventing article will be described.

"Water scale prevention article"
The scale adhesion preventing article according to the present embodiment contains one or more selected from the group consisting of zirconium oxide, hafnium oxide, and rare earth oxides in at least a region where scale may adhere to the surface of the substrate. 1 or 2 selected from the group consisting of carboxylic acid, carboxylate and chelating agent when scale adheres to the surface of the film. There is provided a scale removing means for removing using an aqueous solution containing the above (hereinafter also referred to as a water-soluble scale adhesion preventing substance aqueous solution).

The substrate constitutes the main body of the scale adhesion preventing article, and various shapes are selected and used depending on the shape and specifications of the target article. The substrate is not particularly limited, and examples thereof include ceramics (inorganic products) such as glass and ceramics, metal products such as stainless steel, and metal composite products such as cocoons. In terms of the excellent prevention effect, sanitary ware such as toilets and washbasins, tiles used in bathrooms and washrooms, tableware such as food dishes, bowls, and glazed products can be mentioned.
Also, a plastic using ceramic as a filler can be used. In this case, what is necessary is just to form said film on the surface of the plastic containing this filler.

  The region where this film is to be formed needs to be at least a region where dirt may adhere, but of course, the above-described film may be formed without leaking over the entire surface of the substrate.

This coating must contain one or more selected from the group consisting of zirconium oxide (ZrO ₂ ), hafnium oxide (HfO ₂ ), and rare earth oxides, which are excellent in preventing adhesion of scales. is there. Examples of rare earth oxides include yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), and terbium (Tb). An oxide containing one or more selected from the group consisting of dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), Examples thereof include yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, and dysprosium oxide.

The content of one or more selected from the group consisting of zirconium oxide, hafnium oxide and rare earth oxide is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. is there.
If the total content of these oxides is 50% by mass or more, by using in combination with a method of flowing down an aqueous solution of water-soluble scale adhesion preventing substance described later, an excellent scale adhesion prevention effect is sustained over a long period of time. be able to. Moreover, even when scales adhere, the scales can be easily removed by a simple operation such as wiping with water.

On the other hand, if the total content of these oxides is less than 50% by mass, the effect of preventing the film from adhering to the scale becomes insufficient, and if the scale adheres, the scale can be easily removed by a simple operation such as wiping. There is a risk that it will not be possible.
Examples of components other than these zirconium oxide, hafnium oxide, and rare earth oxide include aluminum oxide and titanium oxide.

The mechanism for preventing adhesion of scale in the coating is considered as follows, for example, when the base is glass or ceramic.
As a component of scale, a lot of silica (SiO ₂ ), calcium (Ca), and magnesium (Mg) is contained. Of these, calcium and magnesium can be removed relatively easily with an acidic detergent or the like, and are not so serious as components of scale dirt.
On the other hand, the silica (SiO ₂ ) content has strong adhesion and cannot be easily removed even by using a chemical such as a strong acid or strong alkali. The reason for the strong adhesion of the silica component is that a large amount of silica component is contained in the glaze and glass of the base and is the same component as the water scale, so that chemical bonding occurs.
In addition, when a siliceous film is formed on the surface of the substrate in order to prevent the adhesion of scale, the silica content of the coating and the silica content in the scale are combined.

  In order to prevent this silica-to-silica bond, it is effective to provide a water-repellent layer made of a silicone resin or a fluororesin on the surface of the substrate and prevent the silica-to-silica chemical bond with this water-repellent layer. However, these silicone resins and fluororesins are weakly bonded to the glass and ceramics constituting the substrate, and therefore the water-repellent layer is easily peeled off from the substrate, and the effect of preventing adhesion of scale cannot be expected over a long period of time.

Therefore, in the present embodiment, at least a region of the surface of the substrate where dirt may adhere is selected from the group of zirconium oxide, hafnium oxide, and rare earth oxide instead of the water-repellent layer made of silicone resin or fluorine resin. A film containing one or more of the above was formed.
These zirconium oxides, hafnium oxides, and rare earth oxides do not have the possibility of forming a strong chemical bond with silica, which is a scale component, and can easily remove scale by combining with an aqueous solution of a water-soluble scale adhesion prevention substance. it can.

The thickness of the coating is preferably 0.01 μm or more and 1 μm or less.
This is because the above range is a range that can ensure the effect of preventing the scale from adhering to the coating and the design properties such as the color tone of the substrate, and when the thickness of the coating is less than 0.01 μm, the prevention of scaling from adhesion becomes insufficient. On the other hand, if the thickness exceeds 1 μm, the transparency of the coating is lowered, and the design properties such as the color tone of the substrate are lowered.

This coating can be formed on the substrate by the following method, for example.
That is, one or more components selected from the group consisting of zirconium, hafnium, alkoxides of rare earth elements, hydrolysates of these alkoxides, chelate compounds of these alkoxides, and chelate compounds of these alkoxide hydrolysates are oxidized. The total mass% when converted to a product is adjusted so as to be 50 mass% or more of the entire solid content to prepare a coating solution.

Although it does not restrict | limit especially as said alkoxide, For example, propoxides, such as butoxides, such as a zirconium normal butoxide, and a zirconium tetrapropoxide, can be mentioned. These butoxides and propoxides are preferable because they have an appropriate hydrolysis rate and can form a film having a uniform film quality.
Examples of alkoxides other than zirconium include alkoxides such as hafnium, yttrium, lanthanum, and cerium.

  The hydrolyzate of the alkoxide is not particularly limited, and examples thereof include hydrolysates of alkoxides such as zirconium, hafnium, yttrium, lanthanum, and cerium, and hydrolysates of these alkoxides. . There is no restriction | limiting in particular as a hydrolysis rate of this hydrolyzate, The thing in the range of more than 0 mol%-100 mol% can be used.

These alkoxides and alkoxide hydrolysates have high hygroscopicity, are unstable, and do not have sufficient storage stability.
Therefore, in consideration of ease of handling, alkoxide chelate compounds obtained by chelating these alkoxides and alkoxide hydrolysates, and chelate compounds of alkoxide hydrolysates are preferable.

  Examples of the alkoxide chelate compound include alkoxide, ethanolamine such as monoethanolamine, diethanolamine and triethanolamine, β-diketone such as acetylacetone, methyl acetoacetate, ethyl acetoacetate, diethyl malonate, and ethyl phenoxyacetate. A reaction product with one or more hydrolysis inhibitors (compounds) selected from the group of carboxylic acids such as β-keto acid esters, acetic acid, lactic acid, citric acid, benzoic acid, malic acid, etc. Can be mentioned. Here, the hydrolysis inhibitor is a compound having an action of forming a chelate compound with an alkoxide and suppressing the hydrolysis reaction of the chelate compound.

  In addition, as a chelate compound of the above alkoxide hydrolyzate, alkoxide, ethanolamine such as monoethanolamine, diethanolamine and triethanolamine, β-diketone such as acetylacetone, methyl acetoacetate, ethyl acetoacetate, diethyl malonate , One or more hydrolysis inhibitors (compounds) selected from the group of carboxylic acids such as β-keto acid esters such as ethyl phenoxyacetate, acetic acid, lactic acid, citric acid, benzoic acid and malic acid Mention may be made of reaction products. The definition of the hydrolysis inhibitor is as described above.

The ratio of the hydrolysis inhibitor to the alkoxide or alkoxide hydrolyzate is preferably 0.5 mol times to 4 mol times the total of zirconium, hafnium and rare earth elements contained in the alkoxide or alkoxide hydrolyzate, More preferably, it is 1 mol times-3 mol times.
Here, if the above ratio is less than 0.5 mol times, the coating solution is insufficiently stable. On the other hand, if it exceeds 4 mol times, hydrolysis is suppressed even after heat treatment. This is because the agent remains in the film, and as a result, the hardness of the film decreases.

  These alkoxide chelate compounds and zirconium alkoxide hydrolyzate chelate compounds are prepared by dissolving an alkoxide or alkoxide hydrolyzate in a solvent, adding a hydrolysis inhibitor, and chelating in the obtained solvent. It may have caused a reaction.

In addition to the alkoxide, the coating solution may contain a solvent, a sol dispersion of each oxide, a water-soluble salt, and the like.
Examples of the solvent include a solvent capable of dissolving or dispersing the above-mentioned zirconium, hafnium, rare earth element alkoxide, hydrolyzate of these alkoxides, chelate compound of these alkoxides, chelate compound of these alkoxide hydrolysates. If there is no particular limitation, it can be used without limitation, for example, water, methanol, ethanol, 2-propanol, 1-butanol and other lower alcohols, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve) ), Ethers such as ethylene glycol monobutyl ether (butyl cellosolve) (cellosolves), ketones such as acetone, dimethyl ketone, diethyl ketone and methyl ethyl ketone, ethylene glycol, etc. Mention may be made of the recall, and the like. In particular, when water is used as a solvent, the stability of the coating solution is reduced if water is contained in an amount that is greater than or equal to the amount of hydrolysis of the alkoxide, so that the amount must be less than the amount of hydrolysis of the alkoxide.

Here, when an alkoxide, a hydrolyzate of alkoxide, or a hydrolyzate of alkoxide and alkoxide is used, a catalyst for controlling the hydrolysis reaction of alkoxide may be added.
Examples of the catalyst include inorganic acids such as hydrochloric acid and nitric acid, and organic acids such as citric acid and acetic acid. Moreover, the addition amount of this catalyst is usually preferably about 0.01 to 10% by mass with respect to the total amount of each component of zirconium, hafnium and rare earth elements in the coating solution. An excessive addition of the catalyst is not preferable because it may corrode the heat treatment furnace during the heat treatment.
In this regard, when the alkoxide chelate compound or the alkoxide hydrolyzate chelate compound is used, it is not necessary to add an acid which is a catalyst for controlling the hydrolysis reaction, and therefore, there is a possibility of corroding the heat treatment furnace during the heat treatment. It is preferable because it is not.

Next, the above-described coating solution is applied to at least a region of the surface of the substrate where there is a possibility that scales adhere.
There is no restriction | limiting in particular as an application | coating method, A spray method, a dip method, a brush coating method, etc. can be applied. In coating, the thickness of the coating film is preferably adjusted so that the film thickness after heat treatment is in the range of 0.01 μm to 1 μm.

The coating film thus obtained is heat-treated at a temperature of 80 ° C. or higher and preferably 250 ° C. or higher in the case of a heat-resistant substrate.
When the heat treatment temperature is lower than 80 ° C, the strength of the obtained coating film may be reduced. If the heat treatment temperature is too high, the substrate may be deformed. Therefore, the heat treatment temperature is adjusted according to the material of the substrate. The atmosphere during the heat treatment is not particularly limited, and is usually performed in an air atmosphere.

  This coating may show some water repellency. In this case, when scale adheres to the surface of the coating, even if an attempt is made to remove the scale using an aqueous solution of a water-soluble scale adhesion preventing substance, the coating repels the aqueous solution, and the aqueous solution spreads over the entire surface of the coating. There are cases where it is not widespread.

  In this case, it is preferable to contain phosphorus in the coating. When phosphorus is contained in the coating, the coating can be made hydrophilic so that it is difficult to repel water, and the aqueous solution of the water-soluble scale adhesion prevention substance can be spread throughout the coating. Therefore, the removability of the scale of this film is further improved.

As this phosphorus, since it is easy to handle, phosphoric acid and its derivative are suitable.
The phosphoric acid and its derivatives include phosphoric acids such as phosphoric acid, polyphosphoric acid and metaphosphoric acid, phosphates such as sodium phosphate, sodium polyphosphate, sodium metaphosphate, sodium polyphosphate, sodium metaphosphate, pyroline There is no particular limitation as long as it is a phosphorus compound having phosphorus (P) in the molecular skeleton, such as a condensed phosphate such as sodium phosphate, a phosphate compound such as phosphate ester, and the like.

The concentration of phosphorus (P) in the coating is preferably 0.001% by mass or more and 10% by mass or less, more preferably 0.01% by mass or more and 10% by mass or less, and further preferably 0.1% by mass or more. And it is 10 mass% or less.
Here, when the concentration of phosphorus (P) is less than 0.001% by mass, it is not possible to expect much improvement in removal of scale, while when the concentration of phosphorus (P) exceeds 10% by mass, The mechanical strength, water resistance, and wear resistance of the coating are reduced.

  The method for adding phosphorus (P) to the coating may be added to the above-mentioned coating solution. Alternatively, the coating solution may be once coated, and then the coating solution containing phosphorus may be further laminated and heated. Good. There are no particular limitations on the coating solution or coating method containing these phosphorus. As described above, the coating film containing phosphorus has a good spread of the aqueous solution of the water-soluble scale adhesion preventing substance, and prevents unevenness of scale adhesion.

As the above-mentioned scale removing means, one or more selected from the group consisting of water-soluble scale adhesion preventing substance aqueous solution, that is, carboxylic acid, carboxylate, and chelating agent, is attached to the scale attached to the surface of the coating. There is no particular limitation as long as this scale can be removed by contact with an aqueous solution containing water. For example, in the case of sanitary ware such as toilets and washbasins, water for washing is stored. A dropping device or a supply device for dropping or supplying the aqueous water-soluble scale adhesion preventing substance aqueous solution to the water may be used for the tank.
Using this dripping device or supply device, the water-soluble scale adhesion prevention substance aqueous solution is dropped or supplied to the water in the tank, and the water containing this water-soluble scale adhesion prevention substance aqueous solution is used for washing to remove scale. If this is the case, the scale of sanitary ware can be easily removed, maintenance is unnecessary, and it is economical.

"Method of preventing scale adhesion on the surface of scale prevention articles"
The method for preventing scale adhesion on the surface of the scale adhesion preventing article of the present embodiment is a method for preventing scale adhesion on the surface of the scale scale adhesion preventing article.
In the above-mentioned scale adhesion preventing article, a sufficient effect cannot be obtained only by the coating film formed on the surface of the substrate.
By causing this aqueous solution of water-soluble scale adhesion preventing substance to flow down on the film, it is possible to effectively prevent scale adhesion for the first time.

  The water-soluble scale adhesion preventive substance is one or more selected from the group of carboxylic acid, carboxylate, and chelating agent. Specifically, citric acid, malic acid, acetic acid, lactic acid, oxalic acid , Ethylenediaminetetraacetic acid, and salts thereof. These substances have a property of binding to calcium ions and magnesium ions in scale.

The concentration of the water-soluble scale adhesion preventing substance contained in the aqueous solution of the water-soluble scale adhesion preventing substance is preferably 0.1 ppm or more and 10,000 ppm or less.
The reason is that if the concentration is less than 0.1 ppm, the effect of preventing the adhesion of scales cannot be obtained. On the other hand, if the concentration exceeds 10000 ppm, a large amount of water-soluble scales adherence prevention substances will precipitate at the time of drying. This is because it becomes obvious. If dirt becomes apparent, it will be necessary to rinse again.
These substances are also contained in commercially available descaling detergents, but their effects are not sufficient by themselves. There are as described above.

In the scale adhesion prevention method of the present embodiment, at least one region selected from the group consisting of zirconium oxide, hafnium oxide, and rare earth oxide is present on the surface of the substrate constituting the scale adhesion prevention article at least in the area where the scale is likely to adhere. Alternatively, by forming a film containing two or more kinds, calcium and magnesium can be prevented by preventing silica from adhering to the surface of the substrate and causing an aqueous solution of a water-soluble scale adhesion preventing substance to flow down on the film. Can be prevented, so that the adhesion of scale can be prevented very efficiently.
Furthermore, the components in the aqueous solution of the water-soluble scale adhesion preventing substance can be combined with the film to serve as a barrier, thereby preventing further adhesion of dirt.

Examples of the method for causing the aqueous solution of the water-soluble scale adhesion preventing substance to flow down on the coating include the following methods.
In the case of a western-style toilet sanitary ware, the above-described microdropping device may be used to gradually release the water-soluble scale adhesion preventing substance aqueous solution or the water-soluble scale adhesion preventing substance itself into the wash water.

In the case of mirrors and kitchen sinks, after cleaning with a normal detergent, wipe with a sponge containing an aqueous solution of water-soluble scale adhesion or spray an aqueous solution of water-soluble scale adhesion with a spray. Can be considered. Further, it is preferable to use an aqueous solution of a water-soluble scale adhesion preventing substance for window glass and tableware of various vehicles when rinsing with a cleaning device.
The concentration of the water-soluble scale adhesion preventing substance in the aqueous solution of the water-soluble scale adhesion preventive substance can obtain a desired effect at a low concentration of about 1 to 1000 ppm.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.

"Example 1"
Apply 10g of nano zirconia aqueous sol (Zirconia concentration: 2% by mass, zirconia is 1% by mass of hafnia to zirconia as an impurity, made by Sumitomo Osaka Cement) on the inside of a ceramic western toilet using a spray. A zirconia coating film was formed.
Next, 10 g of an aqueous sodium pyrophosphate solution containing 0.2% by mass of sodium pyrophosphate was applied onto the zirconia coating film using a spray.

Subsequently, it baked at 300 degreeC in air | atmosphere for 1 hour, and the scale adhesion prevention coating film (coating film) was formed inside this western style toilet bowl. The thickness of the scale coating film was 0.04 μm and contained 97% by mass of zirconia, 1% by mass of hafnia and 2% by mass of phosphorus.
Next, a supply device for supplying citric acid to the water in the tank was installed in the tank portion of the western toilet, so that the wash water in the toilet contained citric acid. The concentration of the citric acid was set to an average of about 100 ppm.

  Next, when the state of scale adhesion of this Western-style toilet was observed for one month without cleaning, the scale adhesion prevention coating film was not peeled off and no scratches were observed. Moreover, no adhesion of scale was observed in the portion where citric acid flowed down.

For comparison, in the above-mentioned Western-style toilet, (a) a part where citric acid does not flow down only with a scale adhesion prevention coating film, (b) a part where there is no scale adhesion prevention coating film and only citric acid flows down, ( c) When there is a part that does not have a coating film for preventing adhesion of scale and does not allow citric acid to flow down, it has been compared. (a), (b), and (c) all have scale attached and can be easily rubbed with a brush. Could not be removed. Particularly in (c), the scale could not be removed at all.
Furthermore, when a zirconia coating film not coated with an aqueous solution of sodium pyrophosphate was baked at 300 ° C. for 1 hour, the coating film formed on the inside of the Western-style toilet has the disadvantage that the washing water does not spread throughout. It was.

"Example 2"
6 parts by mass of a mixture of lanthanum butoxide and aluminum propoxide, 3 parts by mass of ethyl acetoacetate, and 91 parts by mass of 2-propanol were mixed at room temperature (25 ° C.) for 30 minutes, and lanthanum butoxide, aluminum propoxide and ethyl acetoacetate were mixed. A chelate compound was produced as a coating solution. Here, the lanthanum butoxide in the coating solution is converted into lanthanum oxide, the aluminum propoxide is converted into aluminum oxide, and the mass ratios of lanthanum oxide and aluminum oxide are 100: 0 and 60:40, respectively. Two types of coating liquids A and B were prepared.
For comparison, a comparative coating solution C was prepared so that the mass ratio of lanthanum oxide to aluminum oxide was 40:60.

Next, each of these coating liquids A to C is applied onto a porcelain using a spray, and then heat treated at 700 ° C. for 20 minutes in an air atmosphere to form a coating film on the surface of the porcelain. Treated tableware AC was obtained. The thickness of these coating films was 1 μm.
Moreover, the content rate of the lanthanum oxide in the coating film using the coating liquid A was 100 mass%. Moreover, the content rate of the lanthanum oxide in the coating film using the coating liquid B was 60 mass%, and the content rate of aluminum oxide was 40 mass%. Further, the content of lanthanum oxide in the coating film using the coating liquid C was 40% by mass, and the content of aluminum oxide was 60% by mass.
Next, these coated tableware A to C were put into practical use for one month. Here, a dishwasher was used for washing, and washing water having a sodium citrate concentration of 1000 ppm was used at the time of final rinsing.

As a result of observing the state of scale adhesion after one month of these coated tableware A to C, in the coated tableware A, the coating film was only lanthanum oxide, and therefore no scale deposit was observed. In the coated tableware B, since the coating film contained 60% by mass of lanthanum oxide, adhesion of scale was observed, but this scale could be easily removed by rubbing with a scrubber.
On the other hand, in the coated tableware C, since the coating film contained a large amount of aluminum oxide, the adhered water scale could be removed by scrubbing with a scrubber, but it required considerable power to remove.

"Example 3"
Each of the coating liquids A to C of Example 2 was applied onto a porcelain using a spray, and then heat-treated at 700 ° C. for 20 minutes in an air atmosphere to form a coating film on the surface of the porcelain. Then, when it cooled to 400 degreeC, 1 mass% phosphoric acid was apply | coated using the spray. The phosphorus content was 1% by mass of the coating.
In this way, three types of coating-treated tableware D to F were obtained. The thickness of these coating films was 1 μm.
Next, these coated tableware D to F were put into practical use for one month. Here, a dishwasher was used for washing, and washing water having a sodium citrate concentration of 1000 ppm was used at the time of final rinsing.

  When the state of scale adhesion after one month of these coated tableware D to F was observed, the scale removal performance was improved as compared with each of the coated tableware A to C of Example 2. In the coated tableware D, no adhesion of scale was observed throughout. Further, in the coated tableware E, the adhesion of scale was recognized, but this scale could be removed very easily by rubbing with a scrubber. Moreover, in the coating-treated tableware F, although adhesion of scale was recognized, it could be removed more easily than the coating-treated tableware C of Example 2 by rubbing with a scrubber.

Example 4
A 5% aqueous solution of yttrium nitrate was applied to the surface of the glass plate for window glass using a spray to form a coating film.
Here, the spraying time was changed stepwise to obtain five types of coating films A to E having different film thicknesses.
These five types of coating films A to E were heat-treated at 400 ° C. for 1 hour to obtain five types of yttrium oxide coating films A to E.
In these yttrium oxide coating films A to E, the content of yttrium oxide was almost 100% by mass.

When the thickness of these yttrium oxide coating films A to E was measured by film metrics, they were 0.005 μm, 0.015 μm, 0.5 μm, 0.9 μm, and 1.2 μm, respectively.
Of these, the yttrium oxide coating film E having a thickness of 1.2 μm was found to be whitened and was unsuitable as a coating film for a glass plate for window glass.

The glass plates on which these yttrium oxide coating films A to D were formed were used for bathroom windows and put into practical use for 3 months. During this time, a sprinkler (a spraying device) was installed so that a 0.05% aqueous solution of sodium ethylenediaminetetraacetate was sprayed into the bathroom once a week.
After observation of the state of scale adhesion of the yttrium oxide coating films A to D after 3 months, no scale adhesion was observed in the yttrium oxide coating films B to D having a film thickness of 0.015 μm or more. In the 0.005 μm yttrium oxide coating film A, adhesion of scale was observed. However, this scale could be removed by rubbing with a scrubber.

"Example 5"
An aqueous solution containing 5% by mass of yttrium nitrate and 0.1% by mass of phosphoric acid was applied to the surface of the glass plate for window glass using a spray to form a coating film.
Here, the spray time was changed stepwise to obtain five types of coating films F to J having different film thicknesses.
These five kinds of coating films F to J were heat-treated at 400 ° C. for 1 hour to obtain five kinds of yttrium oxide coating films F to J.
All of these yttrium oxide coating films F to J had a yttrium oxide content of 98 mass% and a phosphorus content of 1.5 mass%.

When the thicknesses of these yttrium oxide coating films F to J were measured by film metrics, they were 0.005 μm, 0.015 μm, 0.5 μm, 0.9 μm, and 1.2 μm, respectively.
Of these, the yttrium oxide coating film J having a thickness of 1.2 μm was found to be whitened and unsuitable as a coating film for a glass plate for window glass.

The glass plates on which these yttrium oxide coating films F to J were formed were used for bathroom windows and put into practical use for 3 months. During this time, a sprinkler (a spraying device) was installed so that a 0.05% aqueous solution of sodium ethylenediaminetetraacetate was sprayed into the bathroom once a week.
When the adhesion state of the yttrium oxide coating films F to J after 3 months was observed, the removal property of the scale was improved as compared with each of the yttrium oxide coating films A to D of Example 4.

"Example 6"
Apply a nano-zirconia aqueous sol (zirconia concentration: 2% by weight, zirconia is 1% by weight of hafnia to zirconia as an impurity, made by Sumitomo Osaka Cement) using a spray to a stainless steel sink in the kitchen. A zirconia coating film was formed.
Subsequently, it baked at 200 degreeC in air | atmosphere for 1 hour, and formed the coating film (coating film) inside the sink.
The zirconium oxide content in the coating film was 99% by mass, and the hafnium oxide content was 1% by mass. The coating film thickness was 0.2 μm.

  This sink was used as a stainless steel sink in an actual kitchen and was put into practical use for 3 months. During this time, the sink was used as usual, and an aqueous acetic acid solution containing 0.5% acetic acid was applied by spraying after daily use. As a result, even after 3 months, the adhesion of scale was not observed in most places, and the scale could be easily removed by rubbing with a scrubber in places where the adhesion of scale was recognized. .

  In addition, for comparison, the above-mentioned sink has (a) a part where the acetic acid aqueous solution does not flow down only by the coating film, (b) a part where the coating film does not flow and only the acetic acid aqueous solution flows, (c) no coating film, Comparison was made by providing a portion where the aqueous acetic acid solution did not flow down. As a result, all of (a), (b), and (c) were adhered with water scale and could not be easily removed even by rubbing with a scrubber. Particularly in (c), the adhesion of scale was particularly intense.

"Example 7"
Apply a nano-zirconia aqueous sol (zirconia concentration: 2% by weight, zirconia is 1% by weight of hafnia to zirconia as an impurity, made by Sumitomo Osaka Cement) using a spray to a stainless steel sink in the kitchen. A zirconia coating film was formed.
Subsequently, it baked at 200 degreeC in the atmospheric condition for 1 hour, and the coating film was obtained. After this coating film was cooled to room temperature, an aqueous solution of sodium phosphate (containing 0.1% by mass of phosphorus) was applied to the surface of the coating film using a spray and dried at 100 ° C. A coating film (film) was formed.
The zirconium oxide content in the coating film was 98% by mass, the hafnium oxide content was 1% by mass, and the phosphorus content was 1% by mass. The coating film thickness was 0.2 μm.

  This sink was used as a stainless steel sink in an actual kitchen and was put into practical use for 3 months. During this time, the sink was used as usual, and an aqueous acetic acid solution containing 0.5% acetic acid was applied by spraying after daily use. As a result, even after 3 months, no adhesion of scale was observed over the entire range of the sink. Further, since this coating film contains phosphorus, water spreads well on the inner surface of the sink, and the sink becomes easy to wash.

  In the method for preventing scale adhesion on the article surface of the present invention, at least one selected from the group consisting of zirconium oxide, hafnium oxide, and rare earth oxide is applied to at least a region of the surface of the substrate where scale may adhere. When a coating film is formed and scale adheres to the surface of the coating, the scale contains one or more selected from the group of carboxylic acid, carboxylate, and chelating agent. By removing with an aqueous solution, excellent anti-scale adhesion prevention effect can be maintained for a long period of time, and even when scale adheres, it can be easily removed with simple operations such as running water or wiping. Because it can be used, the kitchen, bathroom, toilet, window glass, etc., with a lot of scale adhesion, can be kept beautiful with little care, and its industrial significance is extremely large. It is the casting.

Claims (6)

The surface of an article in which a coating containing one or more selected from the group consisting of zirconium oxide, hafnium oxide, and rare earth oxides is formed on at least a region of the surface of the substrate where dirt is likely to adhere. It is a method to prevent the adhesion of scale,
When scale adheres to the surface of the coating, the scale is removed with an aqueous solution containing one or more selected from the group of carboxylic acid, carboxylate, and chelating agent. A method for preventing scale adhesion on the surface of an article.   The method of claim 1, wherein the coating further contains phosphorus.   3. The content of one or more selected from the group consisting of the zirconium oxide, the hafnium oxide, and the rare earth oxide in the coating is 50% by mass or more. A method of preventing scale adhesion on the surface of an article. Prevention of adhesion of scales in which a coating containing one or more selected from the group consisting of zirconium oxide, hafnium oxide and rare earth oxides is formed on at least a region of the surface of the substrate where scales may adhere. Goods,
When scale adheres to the surface of the coating, the scale is removed using an aqueous solution containing one or more selected from the group of carboxylic acid, carboxylate and chelating agent. A scale adhesion preventing article characterized by comprising means.   5. The scale adhesion preventing article according to claim 4, wherein the coating further contains phosphorus.   6. The content of one or more selected from the group consisting of the zirconium oxide, the hafnium oxide, and the rare earth oxide in the coating is 50% by mass or more. Articles to prevent scale adhesion.