阅读说明：本技术 无机酸去除用珠粒及其制造方法 (Beads for removing inorganic acid and method for producing same ) 是由 柳炳焕 申守一 陈恒教 金泰卿 金钟芸 于 2019-10-21 设计创作，主要内容包括：本发明涉及无机酸去除用珠粒及其制造方法。更详细而言,涉及无机酸的去除性能优异,且可以减少作业时可能产生的危险因素,可以使二次污染最小化,而且可以显著提高去除效率的无机酸去除用珠粒及其制造方法。(The present invention relates to beads for removing inorganic acid and a method for producing the same. More particularly, the present invention relates to beads for removing inorganic acid, which have excellent removal performance of inorganic acid, can reduce risk factors that may be generated during operation, can minimize secondary pollution, and can remarkably improve removal efficiency, and a method for manufacturing the same.)

1. A particle-type bead for removing a seed-core-shell type inorganic acid, comprising:

a seed layer comprising clay;

a core layer located outside the seed layer and comprising sodium bicarbonate, hydrated lime, and clay; and

a shell layer wrapping the core layer and containing calcium hydroxide.

2. The particulate beads for inorganic acid removal according to claim 1, wherein the particulate beads comprise hydrated lime 10 to 150 parts by weight and clay 1 to 100 parts by weight based on 100 parts by weight of sodium hydrogencarbonate.

3. The particulate inorganic acid removing bead according to claim 1, wherein the core layer has 40 to 99 volume percent with respect to the whole bead.

4. The particulate inorganic acid removing beads according to claim 1, wherein the clay is selected from any one of kaolin, halloysite, sericite, pyrophyllite, montmorillonite, saponite, beidellite, laponite, vermiculite and a mixture thereof.

5. The particulate inorganic acid removing bead according to claim 1, wherein the core layer further contains an organoalkoxysilane.

Technical Field

The present invention relates to beads for removing inorganic acid and a method for producing the same.

More particularly, the present invention relates to beads for removing inorganic acid, which have excellent removal performance of inorganic acid, can reduce risk factors that may be generated during operation, can minimize secondary pollution, and can remarkably improve removal efficiency, and a method for manufacturing the same.

Background

As the use of various petrochemicals increases around life, the incidence of compound leakage accidents is also increasing. Such chemical substance leakage accidents involve risks such as toxicity, flammability, secondary chemical reaction, and explosion depending on the leaked components, and thus have adverse effects on human bodies and the environment, and means for effectively dealing with the leakage accidents are required.

Generally, when inorganic acid leaks at a production site, a neutralization treatment mode of coating an alkaline disaster preventive agent is utilized. In particular, hydrofluoric acid among inorganic acids has a high toxicity, and if it cannot be completely removed practically effectively, it causes a serious problem in terms of environmental problems due to leakage.

Since the basic disaster preventive agent used in such a method of removing leaked inorganic acid is different in characteristics such as the manner of charging, the reaction time, the occurrence of secondary pollution, and storage management depending on the components, there are many cases where it is necessary to consider the charging individually in the treatment step.

In particular, inorganic acids are difficult to control during neutralization due to the high heat of neutralization. In addition, secondary pollutants are generated, which causes environmental pollution or damage to human body, and requires post-treatment. In particular, in the case of hydrofluoric acid, it is more hazardous.

As a conventional technique for removing such inorganic acids, for example, patent document 1 described below discloses a method for removing a strong acid and calcium carbonate using a mixture, but the method causes a severe exothermic reaction and still has a problem in removal efficiency, and the exothermic reaction is severe and explosive neutralization is performed, so that the distance that can be practically used cannot be approached, and the neutralization efficiency is limited due to heat generation.

Therefore, it is necessary to develop a novel remover for efficiently removing inorganic acids, which is easy to put into practice, can control the heat and rate generated during the neutralization reaction, is harmless to the human body and the environment, and does not require a complicated step such as post-treatment.

Disclosure of Invention

The purpose of the present invention is to provide beads for removing inorganic acids, which can effectively treat inorganic acids.

In particular, in the case of inorganic acids, there are problems such as the risk of contact with moisture, difficulty in controlling the high neutralization heat generated during neutralization treatment, and rapid increase in reaction rate. Therefore, in order to solve this problem, it is an object to provide beads for removing inorganic acid, which stably perform a reaction to reduce the risk, can reduce the reaction heat, and can easily control the neutralization treatment operation.

In particular, the present invention provides an excellent bead for removing inorganic acid, which has significantly improved efficiency in removing hydrofluoric acid by neutralization.

Further, the present invention aims to provide inorganic acid-removing beads having excellent storage characteristics without causing a large change in physical properties with respect to moisture or temperature.

Another object of the present invention is to provide beads for removing inorganic acid, which can rapidly treat a large amount of inorganic acid and can significantly improve the efficiency of neutralization treatment.

To achieve the above object, one embodiment of the present invention relates to inorganic acid-removing beads comprising sodium bicarbonate, hydrated lime and clay.

One embodiment of the present invention may be in the form of beads produced by mixing a powder composition containing sodium bicarbonate, hydrated lime, and clay.

Another embodiment of the present invention may be a bead having a shell layer formed by charging the powder composition onto the surface of a seed using clay.

Another embodiment of the present invention is directed to a composition having a core layer comprising sodium bicarbonate, hydrated lime and clay; and a core-shell type inorganic acid removing bead including a shell layer of calcium hydroxide covering the shell layer.

Another embodiment of the present invention relates to a method for producing a core-shell type inorganic acid-removing bead, in which after a seed is produced from clay, a mixed powder containing sodium bicarbonate, hydrated lime and clay is applied to the surface of the seed particle to form a core layer, and a composition containing calcium hydroxide is applied around the core layer to form a shell layer, thereby producing a core-shell type inorganic acid-removing bead.

The beads for removing inorganic acid according to the present invention have advantages that the beads for removing inorganic acid have excellent neutralization treatment performance and can rapidly and efficiently treat a large amount of inorganic acid.

In particular, there is an advantage that various hazardous factors including a violent reaction and high heat of neutralization generated during the neutralization treatment of the inorganic acid can be easily reduced or controlled, and workability can be improved.

In addition, there are advantages in that damage to the human body or the environment due to secondary pollution can be minimized, sensitivity to moisture or temperature is reduced, and long-term storage stability is significantly improved.

In particular, in the present invention, in the case of the core-shell type inorganic acid removing beads containing the composition of the present invention, it is preferable to prevent a violent reaction or high neutralization heat generated at the time of neutralization treatment and to achieve an effect of removing the inorganic acid, particularly, hydrofluoric acid, which has been difficult to remove in the past, with very high efficiency.

In addition, in the present invention, in the case of the inorganic acid removal beads having a 2-layer shape including a core-shell layer containing the ingredient of the present invention on the outer surface of the clay seed, when the beads are produced by forming the core layer well on the surface of the clay seed, since the beads are less crushed or the produced beads are less broken, the beads are high in long-term use and superior in morphological stability. For example, even if the 1m drop test is performed 50 times, the effect of very stabilizing the increase of the degree of breakage by 50% or more is exhibited, and the effect of removing the inorganic acid such as hydrofluoric acid is excellent, and the exothermic reaction and the like are excellent without being vigorously performed.

In particular, in the present invention, by forming a layer containing calcium hydroxide as the outermost layer, the outer layer is also cured to be porous and hardened when absorbing moisture, and therefore there is no difference in neutralization efficiency. In addition, although the beads for removing inorganic acid are neutralized with an inorganic acid such as hydrofluoric acid, the bead shape retention property is further increased, and the beads can be recovered in a better bead shape after use. Therefore, the beads are prevented from collapsing in shape and being blown off by wind to form a new pollution source.

Drawings

Fig. 1 is a graph showing the hydrofluoric acid removal rate results of the inorganic acid removing beads according to one embodiment of the present invention.

Detailed Description

The beads for removing an inorganic acid of the present invention and the production method thereof will be described in detail below. The invention will be better understood from the following examples.

The following examples are for illustrative purposes of the present invention and are not intended to limit the scope of protection as defined by the appended claims.

In this case, technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art, unless otherwise defined. In addition, when not specifically stated in the text, the singular form used in the specification and the claims may mean the plural form, and "comprising" means that the mentioned constituent element does not exclude the presence or addition of one or more other constituent elements.

The present invention is a novel inorganic acid remover that solves the problems of conventional inorganic acid removers, and an invention in the form of an inorganic acid remover.

That is, the present invention provides a novel inorganic acid neutralizing agent which solves the problems of decomposition or strength reduction due to moisture in the air when a conventional inorganic acid removing agent is stored or put into neutralization treatment, and when removing an inorganic acid, not only solves the problem of difficulty in controlling high neutralization heat generated by a conventional sharp neutralization reaction, but also solves the problem of difficulty in recovery due to pulverization into powder when the inorganic acid removing agent is brought into contact with moisture during neutralization, and has an excellent neutralizing effect. In addition, the neutralization efficiency is further increased.

Therefore, the present invention has developed beads for removing inorganic acid, which can ensure stability, have low neutralization heat, can easily control dispersion, and can perform a neutralization reaction with improved efficiency.

To achieve the above object, one embodiment of the present invention relates to inorganic acid-removing beads comprising sodium bicarbonate, hydrated lime and clay.

One embodiment of the present invention may be a bead-shaped product produced by mixing a powder composition containing sodium bicarbonate, hydrated lime and clay.

Another embodiment of the present invention is a bead having a shell layer formed by charging the powder composition onto the surface of a seed using clay.

Another embodiment of the present invention is directed to a composition having a core layer comprising sodium bicarbonate, hydrated lime and clay; and a core-shell type inorganic acid removing bead including a shell layer of calcium hydroxide covering the core layer.

Another embodiment of the present invention relates to a method for producing core-shell inorganic acid-removing beads, in which after producing seeds from clay, a mixed powder containing sodium bicarbonate, hydrated lime, and clay is applied to the surfaces of the seed particles to form a coating layer, and a composition containing calcium hydroxide is applied around the coating layer to form a shell layer.

In the present invention, the removal target is an inorganic acid, and for example, one or two or more leak components selected from the group consisting of an inorganic acid such as hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, and hydrofluoric acid can be removed.

The beads for removing inorganic acid and the method for producing the same according to the present invention will be specifically described below.

One embodiment of the present invention provides mineral acid removal beads comprising sodium bicarbonate, hydrated lime and clay.

In the present invention, when beads composed of the above-mentioned 3 components are used, there is an effect that the beads are effective as an active component for neutralization treatment by a contact reaction with an inorganic acid, and the beads can prevent a high temperature or a rapid temperature rise or a violent reaction due to the heat of neutralization, and can reduce the risk of secondary pollution.

It is effective in the following respects when compared with other neutralizing agents that generate high heat of neutralization or emit harmful substances: not only stable neutralization treatment can be realized, but also post-treatment due to secondary pollution is not required, and in addition, the problems that the bead shape is broken and is difficult to recover or the powder is blown away to cause secondary pollution and the like do not occur during the neutralization treatment, so that the method is harmless to human bodies and can prevent environmental pollution.

According to an embodiment of the present invention, the inorganic acid removing beads are of a pellet type, and have a shape different from that of the powder, so that the beads can be sprayed from a long distance, and the beads are very effective in performing the neutralization treatment without approaching the accident site caused by the leakage of the inorganic acid.

Such beads are made by binding of ingredients comprising sodium bicarbonate, hydrated lime and clay.

The inorganic acid-removing beads according to the present invention have the following effects by a combination of these components: not only can realize a stable solid shape, but also can be thrown to a target site at a long distance without scattering when thrown to an acid leakage site, thereby having excellent neutralization treatment workability. Also, a violent reaction generated during the neutralization treatment or a sharp temperature rise due to a high reaction heat can be prevented, which is more effective in achieving the neutralization performance in that the treatment capacity can be increased or the like.

In the present invention, the composition ratio of the components of the inorganic acid-treated beads is not limited as long as the object of the present invention is achieved, but for example, it is preferable to use 10 to 150 parts by weight of hydrated lime and 10 to 100 parts by weight of clay with respect to 100 parts by weight of sodium hydrogencarbonate, and it is more preferable to use 80 to 120 parts by weight of hydrated lime and 30 to 80 parts by weight of clay with respect to 100 parts by weight of sodium hydrogencarbonate in view of advantages such as neutralization efficiency and shape-retaining property, but it is not limited within the range to achieve the object of the present invention.

The present invention is not limited to the range in which the above-mentioned decrease in the performance of the beads does not occur, andmay contain calcium carbonate (CaCO)₃) Sodium carbonate (Na)₂CO₃) And the like.

These components are more preferable in that the rapid increase in temperature is more suppressed during the neutralization treatment with the inorganic acid, the strength of the beads can be increased, and the shape of the beads can be prevented from being broken due to the decrease in strength even after the neutralization treatment with the inorganic acid.

In this case, the content is not limited to a large amount, and may be, for non-limiting example, 1 to 50 parts by weight based on 100 parts by weight of the sodium hydrogencarbonate.

The clay used in the present invention is not limited as long as it is a clay used in the art, and may be any one or more selected from kaolin (kaolinite), halloysite (halloyite), sericite (serite), pyrophyllite (pyrophyllite), montmorillonite (montmorillonite), saponite (saponite), beidellite (beidellite), laponite (laponite), vermiculite (vermiculite), and mixtures thereof, for example, but is not necessarily limited thereto.

In the present invention, the method for producing the inorganic acid remover beads is a method for producing inorganic acid remover beads comprising sodium bicarbonate, hydrated lime and clay by using a mixed powder of the above components, and the production method is not particularly limited, but the beads are produced by a dry method using a circular drum as an example.

The dry method is a method in which appropriate amounts of sodium bicarbonate, hydrated lime and clay are charged into a circular drum, and beads are produced by the rotation speed of the circular drum, which can be adjusted within a range in which the size of the target particles is controlled, without any significant limitation.

The dry method is a method in which a seed is produced by adding clay to a circular drum, and then appropriate amounts of sodium bicarbonate, hydrated lime and clay are added to coat the seed, thereby producing core-shell shaped beads.

In the dry method, after clay is added to a circular drum to produce a seed using clay for bead formation, a core layer is formed on the seed by further adding appropriate amounts of sodium bicarbonate, hydrated lime and clay, and then clay and calcium hydroxide powder are added to form a shell layer as a calcium hydroxide layer outside the core layer.

Of course, the core-shell beads may be produced by charging appropriate amounts of sodium bicarbonate, hydrated lime and clay without a seed to form the core layer, and then charging clay and calcium hydroxide powder to form a shell layer of calcium hydroxide on the outside of the core layer.

In the present invention, it is more preferable to provide the inorganic acid-removing beads having a core-shell structure, which are produced by charging a powder containing the above clay and calcium hydroxide into a core layer containing the above sodium hydrogencarbonate, hydrated lime and clay to form a shell layer, in order to ensure further improved performance and long-term stable performance.

In the present invention, when a layer containing calcium hydroxide and clay is further provided outside the layer containing sodium hydrogencarbonate, slaked lime and clay, the effect of further promoting the neutralization with an inorganic acid can be more excellent, and the hardness of the beads can be maintained even if the beads are neutralized with an inorganic acid, which is more preferable. It is not clear that the inclusion of the calcium hydroxide of the present invention is more preferable because the outer layer of the calcium hydroxide is cured to be porous and hardened even if it absorbs moisture, and therefore, the beads can be recovered while maintaining their shape during neutralization, and the beads are prevented from being blown off and becoming a new contamination source.

The composition ratio of the composition comprising the above-mentioned binder of sodium hydrogencarbonate, hydrated lime and clay is not necessarily limited, but for example, it is preferable to comprise 10 to 150 parts by weight of hydrated lime and 1 to 100 parts by weight of clay with respect to 100 parts by weight of sodium hydrogencarbonate. This is because, within the above range, the composite particles constituting the core layer are excellent in solid shape strength, suppress a drastic reaction, and easily control the neutralization heat, and are more effective in achieving an improved neutralization treatment performance in particular.

In particular, when the calcium hydroxide is formed as the outermost shell, it has a more advantageous characteristic for protecting the core layer in terms of maintaining the strength of the bead. In addition, in a site where acid leakage occurs, the permeation of the treatment target substance into the core layer can suppress the occurrence of a violent reaction as compared with the simultaneous reaction when the reaction is performed at the same time as the introduction, and there is an effect that a large amount of heat can be prevented from being immediately generated by neutralization. Further, the bead surface hardens by absorbing moisture and maintains the shape of the beads, so that neutralization treatment can be continued, and porosity can be maintained even if it is hardened as compared with the case of using other neutralizing agents, and the beads have excellent characteristics as compared with other metal hydroxides in that the beads do not cause impermeability to the treatment target substance.

In the present invention, in forming the calcium hydroxide layer, a layer further containing calcium hydroxide and any one component selected from clay or starch may be formed. As a specific embodiment, the shell layer may contain calcium hydroxide and starch, or calcium hydroxide and clay, or calcium hydroxide, starch and clay. At this time, the shell layer may be more effective in improving the binding force of the core layer to the shell layer while improving the properties imparted to the shell layer, in combination with the calcium hydroxide, starch and clay.

According to an embodiment of the present invention, in the beads having the core-shell structure, the volume ratio of the layer containing sodium bicarbonate, hydrated lime and clay in the entire volume of the beads is not particularly limited, but is preferably 40% by volume or more, specifically 60 to 99% by volume, and more specifically 70 to 90% by volume, which is a non-limiting example and is not limited to the above numerical range.

The particle size of the inorganic acid removing beads according to an embodiment of the present invention is not particularly limited, but may be 0.1 to 20mm, specifically 0.2 to 15mm, and more specifically 0.4 to 10 mm. Within the above range, the neutralization treatment efficiency is excellent and the target effect can be obtained, but the neutralization treatment efficiency is not limited to the above range.

According to an embodiment of the present invention, the core particle may further include an organoalkoxysilane in a mixed powder of sodium bicarbonate and clay. The organoalkoxysilane can improve the strength of the core particles by combining with sodium bicarbonate and clay, and has an effect of preventing the particles from being damaged not only when the organoalkoxysilane is put into a neutralization treatment work site but also when the organoalkoxysilane is stored or transported. In addition, the adhesive force with the shell layer can be further enhanced, and the effect is more effective in improving the neutralization treatment performance and efficiency.

The organoalkoxysilane is not limited to a specific one insofar as it does not inhibit the object of the present invention, but includes tetraethoxysilane, tetramethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyldimethoxysilane, methyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane and the like, and is not limited thereto. Preferably, 3-aminopropyltrimethoxysilane can be mentioned.

The content of the above organoalkoxysilane is preferably 0.1 to 3 parts by weight relative to 100 parts by weight of the composition comprising sodium bicarbonate, hydrated lime and clay, so that the neutralization efficiency and advantage of hydrofluoric acid are not impaired and the shape stability is more stabilized.

When the above alkoxysilane is used, a basic substance such as amine is added as a curing agent in a catalytic amount, whereby the curing can be easily performed.

Another embodiment of the present invention provides a method for removing inorganic acids, comprising: the beads for removing inorganic acid are thrown into a place where the inorganic acid leaks, and neutralization and adsorption are performed.

The method of charging the beads may be a spraying method using a spraying device, but is not necessarily limited thereto. The shot beads can be delivered not only from a long distance but also accurately into a contaminated site, unlike the powder shot beads, and therefore, the shot beads are effective in terms of stability and efficiency.

The present invention can avoid the danger including the difficult access or the secondary pollution caused by the violent reaction or the high neutralization heat during the prevention and treatment work due to the leakage of the inorganic acid, and can improve the efficiency to the maximum extent in the neutralization treatment capacity and the treatment time, and is expected to be widely applied to various prevention and treatment fields including the inorganic acid leakage accident.

An example of the inorganic acid-removing beads according to the present invention will be described below, but the present invention is not limited to the following examples.

(example 1)

Kaolin was charged into a circular drum and rotated at 80rpm for 9 hours, thereby producing clay seed particles (moisture content 10 wt%) having an average particle diameter of 2.0 mm. The seed particles thus produced were charged into a circular drum, and then a powder obtained by mixing 33 parts by weight of hydrated lime and 5 parts by weight of clay was charged into 100 parts by weight of sodium hydrogencarbonate, thereby obtaining a mixed raw material powder. The above seeds (excluding the water content) were mixed with the above raw material powders in a composition ratio of 23:77 by weight. Next, while spraying 20 parts by weight of water to 100 parts by weight of the raw material powder, a core layer containing sodium bicarbonate, hydrated lime and a clay binder was formed on the surface of the seed by rotating a circular drum at 80 rpm. A pellet-type bead having an average particle size of 3.4mm of the formed bead was obtained, and it was dried in an oven at 60 ℃ for 30 hours, thereby obtaining a final bead.

The final beads obtained above were put into 300mL Teflon beakers by 8g, 11g, 20g, 30g and 50g, respectively, and 10mL of 52% hydrofluoric acid aqueous solution was sprayed by a sprayer. Then, the reaction time was set to 30 minutes, 60 minutes, and 90 minutes, respectively, and the reaction was stirred at 20rpm, thereby conducting a hydrofluoric acid removal experiment. The solution after the reaction was filtered with filter paper, and the filtered solution was analyzed by Ion chromatography (Ion chromatography) (Metrohm corporation, ICFLEX 930) to analyze the content of the residual hydrofluoric acid, and the removal rate of hydrofluoric acid is shown in fig. 1.

As shown in FIG. 1, it was confirmed that the particulate beads for removing hydrofluoric acid of the present invention, in which only 20g of the beads were added to 10ml of a 52% hydrofluoric acid aqueous solution, exhibited a hydrofluoric acid removal rate of 93% or more regardless of the reaction time.

(example 2)

In example 1, after the finally produced beads were produced, a shell-forming composition of 100 parts by weight of calcium hydroxide, 20 parts by weight of kaolin and 10 parts by weight of flour was added to 100 parts by weight of the beads produced, and a shell layer was formed on the surface of the core particles by rotating a circular drum at 100rpm while spraying 15 parts by weight of water to 100 parts by weight of the additional composition, thereby producing beads for removing hydrofluoric acid. Then, the beads thus produced were put into a ceramic container, put into an oven, and heat-treated at 60 ℃ for 30 hours, to finally obtain beads. The average particle size of the final beads was 3.7 mm. As a result of the hydrofluoric acid removal rate test performed in the same manner as in example 1, it was confirmed that only 20g of the 52% hydrofluoric acid aqueous solution was added to 10ml of the aqueous solution, and that the hydrofluoric acid removal rate of about 99% was exhibited at a reaction time of 30 minutes.

(example 3)

The same experiment as in example 2 was performed except that 3 parts by weight of tetraethoxysilane and 3-aminopropyltrimethoxysilane were added in a ratio of 1:1 parts by weight to 100 parts by weight of the hydrogencarbonate and hydrated lime mixture in forming the nucleating layer in example 2. As a result of the hydrofluoric acid removal rate test performed in the same manner as in example 1, it was confirmed that only 20g of the 52% hydrofluoric acid aqueous solution was added to 10ml of the aqueous solution, and that the hydrofluoric acid removal rate of about 97% was exhibited at a reaction time of 30 minutes. In addition, when the produced inorganic acid remover was subjected to 100 times of falling test at a height of 1m, the bead breakage rate was 8 wt% as compared with example 2, and a remarkably higher effect was obtained as compared with 11 wt% of example 2.

Comparative example

Beads were produced in the same manner as in example 1, except that calcium hydroxide was used instead of sodium hydrogencarbonate in example 1. Using the results of the hydrofluoric acid removal rate test performed in the same manner as in example 1, it was confirmed that the hydrofluoric acid removal rate was only about 75% when 50g of the 52% hydrofluoric acid aqueous solution was added to 10ml of the solution and the reaction time was 90 minutes.

(example 4)

A powder obtained by mixing 50 parts by weight of hydrated lime and 10 parts by weight of clay with 100 parts by weight of sodium bicarbonate was charged to obtain a mixed raw material powder. While spraying 15 parts by weight of water to 100 parts by weight of the raw material powder, a pellet-type bead having an average particle size of 3.2mm was obtained by rotating a circular drum at 90rpm, and the pellet-type bead was dried in an oven at 60 ℃ for 30 hours to obtain a final bead. Using this, the same hydrofluoric acid removal experiment as in example 1 was performed, and the hydrofluoric acid removal rate was 88 wt%.

As described above, the present invention is described by way of the limited examples, but the present invention is provided only for the purpose of facilitating a more complete understanding of the present invention, and the present invention is not limited to the examples described above, and various modifications and variations can be made by those skilled in the art based on the description.

Therefore, the idea of the present invention should not be limited to the illustrated embodiments, and the claims and the equivalent or equivalent modified embodiments of the claims are included in the scope of the idea of the present invention.