1. The easy-to-clean polished glaze is characterized by comprising the following components in parts by weight: 35-45 parts of albite, 5-10 parts of kaolin, 5-10 parts of calcined kaolin, 5-10 parts of calcite, 3-8 parts of wollastonite, 10-20 parts of talc, 8-12 parts of strontium carbonate, 3-5 parts of zinc oxide, 1-5 parts of carrier composition and 1-5 parts of oxidant;

the carrier composition comprises 5-9% of nano silver, 1-5% of nano zinc, 3-10% of titanium dioxide and 1-3% of aluminum oxide.

2. The easy-to-clean glaze polish as claimed in claim 1, wherein the carrier composition further comprises a dispersant in an amount of 1-6% by mass of the carrier composition, an electrolytic assistant in an amount of 1-3% by mass of the carrier composition, and polyethylene in an amount of 65-78% by mass of the carrier composition.

3. The easy-to-clean glaze polish as claimed in claim 2, wherein the dispersant is one or both of zinc stearate and barium stearate.

4. The easy-to-clean polished glaze according to claim 2, wherein the electrolysis auxiliary agent is one or more of sodium hexametaphosphate, sodium chloride and potassium nitrate.

5. The easy-to-clean glaze polish as claimed in claim 1, wherein the oxidizer is potassium chlorate.

6. The easy-to-clean glaze polish according to claim 1, wherein the carrier composition is prepared by: and placing the nano silver, the nano zinc and the titanium dioxide in a ball milling device for ball milling for 10-20 min, adding aluminum oxide, a dispersing agent, an electrolytic auxiliary agent and polyethylene, continuing mixing for 20-30 min, and performing heat treatment to obtain the carrier composition.

7. The easy-to-clean glaze polish as claimed in claim 6, wherein the temperature of the heat treatment is 60 ℃ to 75 ℃, and the time of the heat treatment is 15min to 30 min.

8. A method of preparing an easy-to-clean glaze polish according to any one of claims 1 to 7, comprising the steps of:

respectively grinding albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide;

adding the ground albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide into a mixer, mixing for 10-30 min, adding the carrier composition and the oxidant, heating to 45-85 ℃, mixing and ball-milling for 30-50 min to obtain the polished glaze.

9. The easy-to-clean glaze polishing preparation method as claimed in claim 8, wherein the fineness of the glaze polishing is 300-350 mesh sieve.

10. The easy-to-clean glaze discharging method according to claim 8, wherein the glaze is applied to the tile blank in an amount of 500g/m²-550g/m²。

Background

The glaze is a layer of colorless or colored vitreous thin layer covering the surface of the ceramic product, and the glaze layer is generally prepared by mixing mineral raw materials and specific chemical raw materials according to a certain proportion, grinding the mixture to prepare glaze slip, applying the glaze slip on the surface of a blank body, and calcining the glaze slip to obtain the ceramic product. At present, the firing temperature of the wall and floor tiles in the ceramic building industry is generally 1180-1240 ℃, the firing period reaches 90min, and high firing temperature and long firing period mean high energy consumption and air pollution. Energy conservation and emission reduction are always the directions of efforts in the ceramic industry, and enterprises can save more energy and obtain more profit margins only by reducing the firing temperature and the firing period. In addition, although the antibacterial agent is added into the formula system of the glaze polishing in the prior art to achieve a certain antibacterial effect, the compatibility and chromatic aberration between the antibacterial component and other components of the glaze polishing cause that the prepared glaze polishing cannot form a smoother surface on the surface of a brick blank, and the antifouling effect and the wear-resisting effect are deteriorated with the lapse of time,

in conclusion, the above problems still remain to be solved in the field of glaze polishing.

Disclosure of Invention

Based on the technical scheme, the invention provides an easy-to-clean glaze-polishing, which aims to solve the problems that in the prior art, the compatibility of glaze-polishing components is poor, the surface of a brick blank cannot be smoother, and the antifouling effect and the wear-resisting effect are poor along with the lapse of time, and the specific technical scheme is as follows:

an easy-to-clean glaze polish comprises the following components in parts by weight: 35-45 parts of albite, 5-10 parts of kaolin, 5-10 parts of calcined kaolin, 5-10 parts of calcite, 3-8 parts of wollastonite, 10-20 parts of talc, 8-12 parts of strontium carbonate, 3-5 parts of zinc oxide, 1-5 parts of carrier composition and 1-5 parts of oxidant;

the carrier composition comprises 5-9% of nano silver, 1-5% of nano zinc, 3-10% of titanium dioxide and 1-3% of aluminum oxide.

Further, the carrier composition also comprises a dispersing agent accounting for 1-6% of the carrier composition by mass, an electrolysis assistant accounting for 1-3% of the carrier composition by mass, and polyethylene accounting for 65-78% of the carrier composition by mass.

Further, the dispersing agent is one or two of zinc stearate and barium stearate.

Further, the electrolysis auxiliary agent is one or more of sodium hexametaphosphate, sodium chloride and potassium nitrate.

Further, the oxidant is potassium chlorate.

Further, the preparation method of the carrier composition comprises the following steps: and placing the nano silver, the nano zinc and the titanium dioxide in a ball milling device for ball milling for 10-20 min, adding aluminum oxide, a dispersing agent, an electrolytic auxiliary agent and polyethylene, continuing mixing for 20-30 min, and performing heat treatment to obtain the carrier composition.

Further, the temperature of the heat treatment is 60-75 ℃, and the time of the heat treatment is 15-30 min.

In addition, the invention also provides a preparation method of the easy-to-clean polished glaze, which comprises the following steps:

respectively grinding albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide;

adding the ground albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide into a mixer, mixing for 10-30 min, adding the carrier composition and the oxidant, heating to 45-85 ℃, mixing and ball-milling for 30-50 min to obtain the polished glaze.

Further, the fineness of the glaze polishing is 300-350-mesh sieve.

Further, the glaze polishing is applied to the brick blank body, and the glazing amount is 500g/m²-550g/m²。

In the scheme, the formula of the glaze polishing is optimized, so that the components have excellent compatibility, the glaze polishing with better color development effect can be obtained, the nano silver, the nano zinc, the titanium dioxide and the aluminum oxide are used in a compounding manner, the more remarkable antibacterial effect can be exerted, the carrier composition is formed with the dispersing agent, the electrolytic auxiliary agent and the polyethylene and then is added for use, the good substrate adhesion can keep the antibacterial effect for a long time, and the antifouling effect is stable; the oxidant is added to promote the gas to be discharged, so that a glaze surface with higher smoothness is obtained; in addition, the glaze polishing agent disclosed by the invention is small in high-temperature viscosity, excellent in wear resistance and acid and alkali resistance, suitable for high-temperature quick firing, further saves energy consumption, and is beneficial to industrial production.

Drawings

FIG. 1 is a schematic diagram of a brick sample prepared according to application examples 1-4 of the present invention, wherein 1 in FIG. 1 corresponds to brick sample 1, 2 in FIG. 1 corresponds to brick sample 2, 3 in FIG. 1 corresponds to brick sample 3, and 4 in FIG. 1 corresponds to brick sample 4;

FIG. 2 is a schematic representation of a comparative tile sample 1 prepared according to comparative application example 1 of the present invention;

FIG. 3 is a schematic representation of a comparative brick sample 2 prepared according to comparative application example 2 of the present invention;

FIG. 4 is a schematic representation of comparative tile samples prepared according to comparative application examples 3-6 of the present invention, wherein 5 in FIG. 4 corresponds to comparative sample 3, 6 in FIG. 4 corresponds to comparative sample 4, 7 in FIG. 4 corresponds to comparative sample 5, and 8 in FIG. 4 corresponds to comparative sample 6;

FIG. 5 is a schematic representation of a comparative brick sample 7 prepared in this comparative application example 7;

FIG. 6 is a schematic representation of a comparative brick sample 8 prepared in this comparative application example 8.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to embodiments thereof. It should be understood that the detailed description and specific examples, while indicating the scope of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In one embodiment of the invention, the easy-to-clean polished glaze comprises the following components in parts by weight: 35-45 parts of albite, 5-10 parts of kaolin, 5-10 parts of calcined kaolin, 5-10 parts of calcite, 3-8 parts of wollastonite, 10-20 parts of talc, 8-12 parts of strontium carbonate, 3-5 parts of zinc oxide, 1-5 parts of carrier composition and 1-5 parts of oxidant;

the carrier composition comprises 5-9% of nano silver, 1-5% of nano zinc, 3-10% of titanium dioxide and 1-3% of aluminum oxide.

In one embodiment, the carrier composition further includes a dispersant accounting for 1-6% of the carrier composition by mass, an electrolysis aid accounting for 1-3% of the carrier composition by mass, and polyethylene accounting for 65-78% of the carrier composition by mass. The carrier composition has good heat resistance and chemical stability, can generate stronger cohesive force among particles in the sintering process, does not have the problem of shielding among particles, and simultaneously solves the problem of reducing the antibacterial activity of the carrier composition after high-temperature firing.

In one embodiment, the dispersant is one or both of zinc stearate and barium stearate. The dispersing agent is added in the application, so that the dispersion stability among particles is improved, and the risk of agglomeration to form large particles for sedimentation is reduced.

In one embodiment, the electrolysis auxiliary agent is one or more of sodium hexametaphosphate, sodium chloride and potassium nitrate. The present application helps to further obtain a dispersion-stable carrier composition by enhancing electrostatic repulsion between particles by adding an electrolytic auxiliary.

In one embodiment, the oxidizer is potassium chlorate.

In one embodiment, the carrier composition is prepared by the method comprising: and placing the nano silver, the nano zinc and the titanium dioxide in a ball milling device for ball milling for 10-20 min, adding aluminum oxide, a dispersing agent, an electrolytic auxiliary agent and polyethylene, continuing mixing for 20-30 min, and performing heat treatment to obtain the carrier composition.

In one embodiment, the temperature of the heat treatment is 60-75 ℃, and the time of the heat treatment is 15-30 min.

In addition, the invention also provides a preparation method of the easy-to-clean polished glaze, which comprises the following steps:

respectively grinding albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide;

adding the ground albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide into a mixer, mixing for 10-30 min, adding the carrier composition and the oxidant, heating to 45-85 ℃, mixing and ball-milling for 30-50 min to obtain the polished glaze.

In one embodiment, the fineness of the glaze is 300-350-mesh.

In one embodiment, the glaze is applied on the brick blank body, and the glazing amount is 500g/m²-550g/m²。

In one embodiment, after the glaze polishing is applied to the surface of the brick blank body, the brick blank body is placed in a furnace to be fired, and the polished ceramic is obtained.

In one embodiment, the firing temperature is 950-1100 ℃, and the firing time is 40-80 min. The glaze polishing method has the advantages of lower firing temperature and firing time, and can reduce production energy consumption to a certain extent.

In the scheme, the formula of the glaze polishing is optimized, so that the components have excellent compatibility, the glaze polishing with better color development effect can be obtained, the nano silver, the nano zinc, the titanium dioxide and the aluminum oxide are used in a compounding manner, the more remarkable antibacterial effect can be exerted, the carrier composition is formed with the dispersing agent, the electrolytic auxiliary agent and the polyethylene and then is added for use, the good substrate adhesion can keep the antibacterial effect for a long time, and the antifouling effect is stable; in addition, the glaze polishing agent disclosed by the invention is small in high-temperature viscosity, excellent in wear resistance and acid resistance, suitable for high-temperature quick firing, further saves energy consumption, and is beneficial to industrial production.

Embodiments of the present invention will be described in detail below with reference to specific examples.

Example 1:

an easy-to-clean polished glaze preparation method comprises the following steps:

placing 5g of nano silver, 5g of nano zinc and 3g of titanium dioxide in a ball milling device for ball milling for 20min, adding 3g of aluminum oxide, 6g of dispersing agent, 3g of electrolytic auxiliary agent and 75g of polyethylene, continuously mixing for 30min, and carrying out heat treatment to obtain a carrier composition;

respectively grinding 35g of albite, 5g of kaolin, 10g of calcined kaolin, 10g of calcite, 8g of wollastonite, 20g of talc, 12g of strontium carbonate and 3g of zinc oxide;

adding the ground albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide into a mixer, mixing for 10min-30min, adding 5g of carrier composition and 1g of oxidant, heating to 45 ℃, mixing and ball-milling for 50min to obtain the polished glaze.

Example 2:

an easy-to-clean polished glaze preparation method comprises the following steps:

placing 9g of nano silver, 1g of nano zinc and 10g of titanium dioxide in a ball milling device for ball milling for 10min, adding 3g of aluminum oxide, 1g of dispersing agent, 1g of electrolytic auxiliary agent and 75g of polyethylene, continuously mixing for 30min, and carrying out heat treatment to obtain a carrier composition;

respectively grinding 45g of albite, 10g of kaolin, 5g of calcined kaolin, 5g of calcite, 3g of wollastonite, 10g of talc, 8g of strontium carbonate and 5g of zinc oxide;

adding the ground albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide into a mixer, mixing for 30min, adding 5g of the carrier composition and 5g of the oxidant, heating to 45 ℃, mixing, and carrying out ball milling for 30min to obtain the polished glaze.

Example 3:

an easy-to-clean polished glaze preparation method comprises the following steps:

placing 5g of nano silver, 3g of nano zinc and 7g of titanium dioxide in a ball milling device for ball milling for 15min, adding 2g of aluminum oxide, 5g of dispersing agent, 2g of electrolytic auxiliary agent and 76g of polyethylene, continuously mixing for 20min, and carrying out heat treatment to obtain a carrier composition;

grinding 40g of albite, 6g of kaolin, 8g of calcined kaolin, 8g of calcite, 5g of wollastonite, 15g of talc, 10g of strontium carbonate and 4g of zinc oxide respectively;

adding the ground albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide into a mixer, mixing for 20min, adding 4g of the carrier composition and 4g of the oxidant, heating to 65 ℃, mixing, and carrying out ball milling for 40min to obtain the polished glaze.

Example 4:

an easy-to-clean polished glaze preparation method comprises the following steps:

placing 9g of nano silver, 5g of nano zinc and 10g of titanium dioxide in a ball milling device for ball milling for 20min, adding 2g of aluminum oxide, 5g of dispersing agent, 3g of electrolytic auxiliary agent and 66g of polyethylene, continuously mixing for 25min, and carrying out heat treatment to obtain a carrier composition;

grinding 40g of albite, 8g of kaolin, 8g of calcined kaolin, 8g of calcite, 5g of wollastonite, 15g of talc, 10g of strontium carbonate and 4g of zinc oxide respectively;

adding the ground albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide into a mixer, mixing for 25min, adding 4g of the carrier composition and 3g of the oxidant, heating to 65 ℃, mixing, and carrying out ball milling for 45min to obtain the polished glaze.

Comparative example 1:

a glaze polishing preparation method comprises the following steps:

respectively grinding 5g of nano silver, 3g of nano zinc, 7g of titanium dioxide, 40g of albite, 6g of kaolin, 8g of calcined kaolin, 8g of calcite, 5g of wollastonite, 15g of talc, 10g of strontium carbonate and 4g of zinc oxide;

adding the ground albite, kaolin, calcined kaolin, calcite, wollastonite, talc, strontium carbonate and zinc oxide into a mixer, mixing for 20min, adding 4g of the carrier composition and 4g of the oxidant, heating to 65 ℃, mixing, and carrying out ball milling for 40min to obtain the polished glaze.

Comparative example 2:

a preparation method of polished glaze comprises the following steps:

43g of albite, 8g of kaolin, 7g of calcined kaolin, 8g of calcite, 5g of wollastonite, 15g of talc, 10g of barium carbonate and 4g of zinc oxide are placed in a mixer for mixing and ball milling for 45min to obtain the polished glaze.

Comparative examples 3 to 8:

the ingredients of the carrier compositions of comparative examples 3-8 are different from example 4, and are otherwise the same as example 4, as shown in table 1 below.

Table 1:

application example 1:

the easy-to-clean glaze prepared in example 1 was applied to a tile blank in an amount of 550g/m²And then fired at 1100 ℃ for 40min to obtain a brick sample 1.

Application example 2:

the easy-to-clean glaze prepared in example 2 was applied to a tile blank in an amount of 550g/m²And then the sample was fired at 1000 ℃ for 50min to obtain a brick sample 2.

Application example 3:

the easy-to-clean glaze prepared in example 3 was applied to a tile blank in an amount of 550g/m²And then fired at 1100 ℃ for 50min to obtain a brick sample 3.

Application example 4:

the easy-to-clean glaze prepared in example 4 was applied to a tile blank at 550g/m²Then placing the mixture at 1100 ℃ for firingAnd (5) obtaining a brick sample 4 after 60 min.

Comparative application example 1:

the polished glaze prepared in comparative example 1 was applied to a tile blank in an amount of 550g/m²And then left to be fired at a temperature of 1100 c for 60min, to obtain comparative brick sample 1.

Comparative application example 2:

the polished glaze prepared in comparative example 2 was applied to a tile blank in an amount of 550g/m²And then fired at 1250 c for 95min to obtain comparative brick sample 2.

Comparative application example 3:

the polished glaze prepared in comparative example 3 was applied to a tile blank in an amount of 550g/m²And then left to be fired at a temperature of 1100 c for 60min, to obtain a comparative brick sample 3.

Comparative application example 4:

the polished glaze prepared in comparative example 4 was applied to a tile blank in an amount of 550g/m²And then left to be fired at a temperature of 1100 c for 60min, to obtain a comparative brick sample 4.

Comparative application example 5:

the polished glaze prepared in comparative example 5 was applied to a tile blank in an amount of 550g/m²And then left to be fired at a temperature of 1100 c for 60min, to obtain comparative brick sample 5.

Comparative application example 6:

the polished glaze prepared in comparative example 6 was applied to a tile blank in an amount of 550g/m²And then placed at 1100 ℃ to be fired for 60min, to obtain a comparative brick sample.

Comparative application example 7:

the polished glaze prepared in comparative example 7 was applied to a tile blank in an amount of 550g/m²And then placed at 1100 ℃ to be fired for 60min, to obtain a comparative brick sample.

Comparative application example 8:

the polished glaze prepared in comparative example 8 was applied to a tile blank in an amount of 550g/m²And then left to be fired at a temperature of 1100 ℃ for 60min, to obtain a comparative brick sample 8.

To verify the compatibility, stability and bacteriostasis of the polishing glazes prepared in examples 1-4 and the polishing glazes prepared in comparative examples 1-8, the following tests were performed:

the stability of the glaze polishing is judged by observing the color development condition of the glaze polishing by naked eyes and whether the conditions of precipitation, glaze phase change, color change and the like appear after standing for 3d by the technicians in the field. And preliminarily detecting the antibacterial activity of the polished glaze, placing the polished glaze of examples 1-4 and the polished glaze of comparative examples 1-8 in an empty plate, respectively placing under an ultraviolet lamp for irradiating for 5min, respectively placing 1mL of 2500-bacterium/mL escherichia coli and 1mL of 2500-bacterium/mL staphylococcus aureus in corresponding test groups, and calculating the bactericidal rate of each group through a conventional test. The results are shown in table 2 below.

Table 2:

the data analysis in table 2 shows that the composite use of nano silver, nano zinc, titanium dioxide and aluminum oxide can exert more significant antibacterial effect, and the composite use of nano silver, nano zinc, titanium dioxide and aluminum oxide, after the composite use of nano silver, nano zinc, titanium dioxide and aluminum oxide, and the composite use of nano silver, nano zinc, titanium dioxide and aluminum oxide, together with the dispersant, the electrolytic assistant and polyethylene, form a carrier composition, the composite use of nano silver, nano zinc, titanium dioxide and polyethylene has more stable antibacterial effect, and the dispersant and the electrolytic assistant are beneficial to improving the stable color development and the stable material body of the glaze throwing system.

Carrying out appearance detection, antifouling detection and antibacterial performance detection on the brick body samples 1-4 of the application examples 1-4 and the comparative brick body samples 1-8 of the comparative application examples 1-8, wherein the antifouling detection is that ink dripping treatment is carried out on the surfaces of the corresponding samples, and the existence of obvious marks is observed; the antibacterial performance is referenced JC/T897-2014 (2017). The results are shown in table 3 below.

Table 3:

as can be seen from the data analysis in Table 3, when the glaze is applied to the surface of the brick body, the prepared brick body has smooth surface, no white spots after polishing, excellent antibacterial performance and small change of the antibacterial performance along with time, which indicates that the brick body has long-acting antibacterial effect. In an antifouling test, the polished glaze has more excellent antifouling performance when being applied to the surface of a brick body; in addition, the firing of comparative brick sample 2 requires higher firing temperature and firing time, and the energy consumption is larger than that of the other groups. The analysis in conjunction with FIGS. 1-6 shows that: FIG. 1 is a schematic diagram of a brick sample prepared according to application examples 1-4 of the present invention, wherein 1 in FIG. 1 corresponds to brick sample 1, 2 in FIG. 1 corresponds to brick sample 2, 3 in FIG. 1 corresponds to brick sample 3, and 4 in FIG. 1 corresponds to brick sample 4; as can be seen from the analysis in FIG. 1, the polished tile body prepared by the invention has no white spots and a smooth surface, which shows that the polished glaze has excellent aesthetic decorative value. FIG. 2 is a schematic representation of a comparative tile sample 1 prepared according to comparative application example 1 of the present invention, but with a few white spots appearing after polishing, illustrating that the preparation of the carrier composition affects the post-polishing quality of the polishing. FIG. 3 is a schematic representation of a comparative tile sample 2 prepared according to comparative application example 2 of the present invention, showing a large number of white dots after polishing, illustrating that the composition of the polished glaze affects the quality of the polished tile. Fig. 4 is a schematic diagram of comparative tile samples prepared according to comparative application examples 3-6 of the present invention, wherein 5 in fig. 4 corresponds to comparative sample 3, 6 in fig. 4 corresponds to comparative sample 4, 7 in fig. 4 corresponds to comparative sample 5, 8 in fig. 4 corresponds to comparative sample 6, no white spots appear after polishing of comparative samples 3-6, fig. 5 is a schematic diagram of comparative tile sample 7 prepared according to comparative application example 7, and fig. 6 is a schematic diagram of comparative tile sample 8 prepared according to comparative application example 8, but a few white spots appear in comparative tile sample 7 and comparative tile sample 8, which indicates that the carrier composition has a certain effect on the polished quality.

In addition, the brick samples 4 and comparative brick samples 1-8 were also tested for wear resistance and acid resistance, and the results are shown in Table 4 below. Wherein, the abrasion resistance of the obtained glazed brick is tested by a glazed brick abrasion resistance tester; acid and alkali resistance: and performing acid and alkali resistance test according to GB/T4100-2006 national standard.

Table 4:

the data analysis in table 4 shows that the abrasion resistance of the glazed brick obtained by the glazed brick abrasion resistance tester method of the brick body sample 4 is more than or equal to 4 grade (6000 revolutions), and the abrasion resistance is better than that of the comparative brick body sample; analysis of acid and alkali resistance test data shows that the polished glaze provided by the invention is applied to the surface of a brick body to endow the brick body with excellent acid and alkali resistance.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.