JP2007062275A - Cleaning method of blackboard - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a cleaning work to be easily performed while having a superior anti-fouling property. <P>SOLUTION: For a blackboard, a photocatalyst is adhered to the surface. For a blackboard, a photocatalyst is adhered to the surface through a hardly-decomposing binder. For the blackboard, the photocatalyst is titanium oxide. The cleaning method for the blackboard comprises the steps of wetting the surface of either one of the blackboard with water to cause fouling with chalk to lift from the surface of the blackboard, and wiping off the blackboard. A surface treating method for the blackboard comprises the step of adhering the photocatalyst to the surface of the blackboard. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a blackboard having excellent antifouling properties and a method for cleaning the blackboard.

  Blackboard characters written with chalk have been erased with blackboard eraser (Rawl), but the chalk marks are difficult to remove completely, and the blackboard becomes whitish and difficult to see with use. I am doing work.

  However, in the cleaning work, a great deal of labor is required to completely erase the traces of chalk on the blackboard. Specifically, the blackboard is cleaned by wiping with a wet towel or the like, but chalk powder tends to remain and the blackboard surface after drying tends to be white. Therefore, to cleanly remove the white chalk powder, it is necessary to wipe with water many times. However, excessive wiping may adversely affect the surface coating of the blackboard and reduce durability. It was.

  Furthermore, if the blackboard is used for a long period of time, the surface paint of the blackboard will be worn out and the chalk will be poorly attached (the writing quality will be poor), putting an extra burden on those who use the blackboard and also looking at the blackboard Therefore, the visibility is lowered.

  An object of this invention is to provide the blackboard which is excellent in antifouling property and can perform a cleaning operation easily in view of the said subject. It is another object of the present invention to provide a blackboard surface treatment method that is easy to clean and can improve writing quality and visibility even when the blackboard is in a used state.

  In order to achieve the above object, the blackboard according to the present invention is characterized in that a photocatalyst is attached to the surface. As a result, it is possible to easily erase the characters on the blackboard written with chalk by erasing the blackboard without leaving a mark on the chalk. Further, even if a little chalk stain remains only by erasing the blackboard, it is possible to easily remove the chalk stain without whitening the blackboard surface by wiping the blackboard surface lightly with water.

  The method for attaching the photocatalyst to the surface of the blackboard is not particularly limited, and a dispersion or solution containing the photocatalyst can be applied by a dip coating method, a blade coating method, a roller coating method, or a brush coating method. In addition, a spray coating method can be used to spray a liquid containing a photocatalyst onto the blackboard. In this case, fine irregularities due to the photocatalyst are formed on the blackboard surface, so excellent writing quality is demonstrated. .

  By using a photocatalyst having a particle diameter as small as possible, it is possible to improve the adhesion to the blackboard. Specifically, the particle diameter of the photocatalyst is preferably several nm to several tens of nm, and more preferably 1 nm to 50 nm. Thereby, antifouling property can be exhibited over a long period of time.

  Furthermore, it is possible to attach a photocatalyst to the surface of the blackboard via a hard-to-decompose binder. A blackboard having a photocatalyst attached to the surface via a hardly decomposable binder can exhibit good antifouling properties for a longer period because the photocatalyst particles are firmly adhered to the blackboard surface by the hardly decomposable binder.

  The hardly decomposable binder can be coated on the blackboard surface prior to the photocatalyst, and then the photocatalyst can be adhered to the surface of the hardly decomposable binder. The hardly decomposable binder can also be dissolved in a dispersion or solution containing a photocatalyst. Thereby, a photocatalyst is coat | covered with a hardly decomposable binder, it becomes difficult for a photocatalyst particle to contact a blackboard surface directly, and it becomes possible to prevent deterioration of the blackboard surface coating.

  Here, the hard-to-decompose binder is a binder having a property that is not easily decomposed or deteriorated by the photocatalytic action of the photocatalyst, for example, an inorganic binder such as water glass, colloidal silica, a hydrolyzate of metal alkoxide, Organic binders such as fluorine-based polymers and silicones can be mentioned, and these can be used alone or in combination of two or more.

  In the present invention, a photocatalyst is a strong reducing power possessed by an electron generated in a conduction band and a hole in a valence band by photoexcitation by irradiating light having a wavelength with energy greater than the band gap. And those that exert the function of decomposing and purifying organic substances such as harmful substances by the strong oxidizing power of holes.

  As a photocatalyst, known metal compound semiconductors such as titanium oxide, zinc oxide, tungsten oxide, iron oxide, and strontium titanate can be specifically used, or one or a combination of two or more thereof can be used. It is preferable to use titanium oxide having an excellent photocatalytic function.

  In order to attach the photocatalyst to the blackboard surface, as described above, a photocatalyst dispersion liquid in which fine particles of the photocatalyst are dispersed in water and / or a solvent can be applied or sprayed on the blackboard surface. In this case, the finely pulverized photocatalyst may be dispersed in water and / or a solvent, but any one of metal alkoxide, metal chloride, metal nitride, and metal organic oxide is used as a raw material for the photocatalyst. If a metal oxide sol is produced from these raw materials, fine particles of the photocatalyst can be easily obtained without going through a pulverization step.

  Specifically, when titanium oxide is used as a photocatalyst, the type with the highest photocatalytic activity among titanium oxides is anatase-type titanium oxide. Therefore, a dispersion liquid (including sol) in which fine particles of anatase-type titanium oxide are dispersed. Can be coated on the blackboard surface.

  In addition, as a photocatalyst, a photocatalyst precursor such as a metal alkoxide or a hydrolyzate of metal alkoxide can be attached to the blackboard surface, and then the photocatalyst precursor is reacted on the blackboard surface to finally form a photocatalyst. It is.

  Specifically, when titanium oxide is used as the photocatalyst, a titanium oxide hydrogen peroxide aqueous solution in which titanium oxide is dissolved in hydrogen peroxide water can be used as the photocatalyst precursor. The aqueous solution of titanium oxide hydrogen peroxide is applied or sprayed on a blackboard and then dried at room temperature to form anatase-type titanium oxide. Furthermore, titanium oxide obtained from a titanium oxide hydrogen peroxide aqueous solution has excellent adhesion to the blackboard surface and can maintain antifouling properties over a long period of time.

  Furthermore, it is possible to use anatase type titanium oxide fine particles added to a titanium oxide hydrogen peroxide aqueous solution. In this case, the aqueous solution of titanium oxide hydrogen peroxide functions as a binder, and the anatase titanium oxide can be firmly adhered to the blackboard surface.

  The blackboard according to the present invention exhibits an excellent antifouling property that chalk stains can be removed by simply wiping with a rarule by attaching a photocatalyst to the surface. Furthermore, since the surface of the blackboard according to the present invention is excellent in hydrophilicity due to the action of the photocatalyst, the chalk dirt adhering to the blackboard surface is lifted by wetting the surface with water, and can be easily removed by simply wiping. It becomes possible.

  The blackboard to which the photocatalyst is attached is not limited to that before use, and may be in a state of being used. That is, the present invention also provides a blackboard surface treatment method characterized by attaching a photocatalyst to the blackboard surface.

  According to the above-described method, not only the antifouling property of the blackboard but also the writing quality and visibility can be improved by surface-treating the blackboard in a considerably used state by a simple method.

  As described above, according to the present invention, excellent antifouling properties are exhibited by attaching a photocatalyst to the surface of the blackboard. Moreover, if a photocatalyst is made to adhere to the blackboard of the state where writing taste and visibility fell by use, not only antifouling property but writing quality and visibility can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a blackboard according to the present invention. The blackboard 1 includes a wooden or steel substrate 2 and a blackboard paint layer 3 formed on the surface of the substrate 2, and the photocatalyst 4 is attached to the surface of the blackboard paint layer 3. In the present embodiment, anatase-type titanium oxide is used as the photocatalyst 4.

The photocatalyst 4 will be described in more detail. In this embodiment, a titanium oxide hydrogen peroxide aqueous solution in which titanium oxide is dissolved in hydrogen peroxide water is used as a titanium oxide raw material, and this is applied to the surface of the blackboard paint layer 3. By spray coating and drying at room temperature, anatase-type titanium oxide having excellent adhesion is formed on the surface of the blackboard paint layer 3. The coating amount of the photocatalyst 4 is preferably such that the weight of the photocatalyst is 0.01 g to 1.0 g per m ² of the blackboard, and is 0.1 to 0.5 g per m ^{2 of} the blackboard. More preferred.

In the present embodiment, tetraethoxysilane is used as a hardly decomposable binder in order to adhere the photocatalyst 4 more firmly to the surface of the blackboard paint layer 3. Tetraethoxysilane is dehydrated and condensed while being hydrolyzed by moisture to finally form SiO ₂ .

  Therefore, when tetraethoxysilane is added to the aqueous solution of titanium oxide hydrogen peroxide, direct contact between the titanium oxide and the blackboard paint layer 3 is suppressed, and the titanium oxide is bonded to the blackboard paint layer 3 via silica. It becomes possible to make it. Thereby, deterioration of the blackboard paint layer 3 due to titanium oxide can be suppressed.

The amount of tetraethoxysilane (SiO ₂ content: 13.8% by weight) added is 0.5 to 4.0 parts by weight, preferably 1.2 to 1 part by weight per 1 part by weight of titanium oxide. 5 parts by weight. Within this range, deterioration of the blackboard paint layer 3 due to titanium oxide can be effectively prevented while maintaining good photocatalytic performance and adhesiveness.

[Adhesion of photocatalyst to blackboard]
There are two types of blackboards, ones that are quite used, and the difference in performance between when the photocatalyst is attached to the surface of each blackboard according to the above embodiment and when the photocatalyst is not attached. Evaluated.

  Specifically, a titanium oxide hydrogen peroxide aqueous solution was used as a photocatalyst raw material, and tetraethoxysilane was added as a hardly decomposable binder to the coating solution. Hereinafter, the detailed preparation method of a coating liquid is demonstrated.

  First, titanium tetraisopropoxide (TIP) and isopropanol (IPA) were mixed (TIP: IPA molar ratio 1: 5) and stirred. Thereafter, a mixed liquid of IPA and water was added to adjust the total composition ratio to TIP: IPA: water = 1: 10: 4, and the liquid temperature was kept at 5 ° C. and stirred. The obtained suspension was subjected to suction filtration to separate fine particles, followed by aeration drying (99 ° C. × 20 hours).

  The obtained dry fine particles were put into 31 W% hydrogen peroxide water and dissolved while stirring at 20 ° C. to obtain a yellow transparent gel. Hydrogen peroxide was added again to obtain a titanium oxide hydrogen peroxide aqueous solution.

  And tetraethoxysilane was added to the titanium oxide hydrogen peroxide aqueous solution, and the coating liquid was prepared. The titanium oxide content in the coating solution was 2.2% by weight. The tetraethoxysilane content relative to the titanium oxide content in the coating solution was titanium oxide: tetraethoxysilane (weight ratio) = 1: 1.3.

The coating solution was spray-coated with a spray gun at a rate of 10 g / m ² of blackboard, and then dried at room temperature for 24 hours.

[Blackboard evaluation method]
The performance was evaluated for two types of blackboards obtained by applying the above processing to a new blackboard and a blackboard in use. As a comparative product, an untreated blackboard not subjected to the above treatment was used as it was. Evaluation items and evaluation criteria are as follows.
(1) Blackboard surface condition ○… Easy to read ×… Difficult to see (2) Ease of writing chalk ◎… Very easy to write ○… Normal ×… Difficult to write (chalk breaks well)
(3) Ease of wiping characters with Rafuru ○… No chalk mark left ×… Chalk character mark left * Note: For the evaluation of the above items (1) to (3), “Used blackboard” "" Was provided after cleaning by a maintenance company.

(4) Workability by maintenance contractors The above four types of blackboards were each cleaned for a certain period of time and cleaned by a maintenance contractor.
○ ... without causing a blackboard of whitening in the blackboard 5m ² per 3 minutes to 5 minutes of work time to clean cleanable △ ... blackboard 5m ² per 7 minutes to 10 minutes of work time, but is part of the surface after the blackboard dry whitened × ... Working time of 10 minutes or more per 5 m ^{2 of} blackboard, the entire surface is whitened after drying the blackboard

[Evaluation results]
Table 1 shows the evaluation results of the new blackboard, and Table 2 shows the evaluation results of the used blackboard. In addition, in the table | surface, the surface-treated product has shown what coated the photocatalyst on the blackboard surface, and the untreated product has shown what has not performed photocatalyst coating, respectively.

  According to Table 1 and Table 2, it can be seen that the workability of the maintenance company is remarkably improved by coating the photocatalyst. Specifically, the surface-treated products were both new and blackboards, and the “workability by vendor” was ○, but the evaluation results for untreated products were Δ It was x on the state blackboard.

  Looking at the difference in these evaluations based on the actual work content, in the surface treatment product, after the blackboard was roughly wiped with rafuru, the entire surface of the blackboard was wetted with a spray bottle and placed for 1 to 2 minutes. Chalk powder floats from the blackboard surface. Therefore, it is possible to cleanly remove the chalk powder by simply draining with a window squeegee in that state and wiping with a towel partially, thereby significantly reducing the work time while suppressing whitening of the blackboard. It becomes possible.

  On the other hand, for untreated products, even if the entire blackboard surface is wetted by spraying, the chalk powder does not lift from the surface of the blackboard. It is necessary to wipe with water. When the “worker's workability” evaluation was Δ, whitening was observed in part of the blackboard surface that was considerably cleaned by wiping with water about 4 times. In the case where the evaluation of “workability by the trader” was ×, water wiping was required 5 times or more to clean the chalk mark, and the blackboard surface after cleaning was whitened.

  In addition, regarding the “ease of writing chalk”, all the surface-treated products were ◎, while the untreated products were ○ to ×. This was thought to be because titanium oxide with high hardness was firmly fixed to the blackboard surface.

  As described above, it was confirmed that by coating the blackboard with the photocatalyst, the antifouling property is excellent, the cleaning work can be easily performed, and the writing quality and the visibility can be improved.

Sectional drawing which shows the blackboard which concerns on this invention

Explanation of symbols

1 Blackboard 2 Substrate 3 Blackboard paint layer 4 Photocatalyst

Claims (5)

A blackboard with a photocatalyst attached to the surface. A blackboard characterized in that a photocatalyst is attached to the surface via a hardly decomposable binder. The blackboard according to claim 1 or 2, wherein the photocatalyst is titanium oxide. A method of cleaning a blackboard, wherein the surface of the blackboard according to any one of claims 1 to 3 is wetted with water, and chalk dirt is lifted off from the surface of the blackboard. A blackboard surface treatment method comprising attaching a photocatalyst to a blackboard surface.

Images