TWI681077B - Coating composition, tin oxide electrode coating, and tin oxide electrode protection method - Google Patents

Abstract

The invention relates to the field of coating, and discloses a coating composition, a tin oxide electrode coating, and a method for protecting a tin oxide electrode. The coating composition contains a mineral powder, a glass powder and an adhesive. The mineral powder contains SiO₂ , Al₂ O₃ , R₂ O, and Fe₂ O₃ , and the SiO₂ content is 60-75% by weight, the Al₂ O₃ content is 25-40% by weight, the R₂ O content is 0.5-2.5% by weight, based on the total weight of the mineral powder, and R is an alkali metal. The tin oxide electrode coating formed by coating the coating composition provided by the present invention is used in a baking kiln stage in glass manufacturing, and can effectively protect the electrodes, so as to ensure smooth production.

Description

Coating composition, tin oxide electrode coating and protection method of tin oxide electrode

The present invention relates to the field of coatings, and more particularly to a coating composition, tin oxide electrode coating, and tin oxide electrode protection method.

The manufacturing process of the existing TFT glass substrate includes an electric boosting furnace heating stage, which generally adopts natural gas and air boosting methods for hot air baking kiln. The heating process of heating the temperature in the kiln from room temperature to 1600°C is generally divided into three stages, and the slope of the heating curve in each stage is different, and the heating rate is also different. The tin oxide electrode in the electric furnace is made of SnO ₂ powder and a variety of additives. Its shortcomings are that it is easy to volatilize and reduce; second, it is poor in thermal shock resistance. During the heating process of the kiln, especially when the fire is too large, a reducing atmosphere is easily formed due to poor fuel control; when the fire is switched over, the temperature in the kiln will fluctuate sharply; after the fire, it will be caused by the rapid change of the heating rate The temperature difference between the upper and lower inside the kiln is too large, which will cause the tin oxide in the electrode brick to be reduced and volatilized, or the electrode will be brittle, which will cause fatal damage to the tin oxide electrode.

Therefore, there is a need to provide a coating that can effectively protect the tin oxide electrode during the hot air baking kiln to protect the electric fluxing equipment.

An object of the present invention is to provide a coating composition which has the advantages of high refractoriness and good plasticity. Another object of the present invention is to provide a tin oxide electrode coating formed by coating a coating composition and a method for protecting the tin oxide electrode by the tin oxide electrode coating, using the coating composition on a tin oxide electrode The protective coating formed on the surface has the advantages of wide temperature range and strong adhesion. The coating protects the tin oxide electrode and makes it slowly warm up, which effectively ensures that the tin oxide electrode is not blocked by the kiln during the baking process. The internal atmosphere is reduced, and it is not affected by the electrode brittleness or performance damage caused by the sudden change of slope at different stages of the heating curve in the kiln and the switching of the heating rate. In addition, the protective coating will eventually fall off after completion of the temperature rise, without going to the working system. Introduce other harmful elements.

In order to achieve the above object, the first aspect of the present invention provides a coating composition, the coating composition containing mineral powder, glass powder and an adhesive, wherein the mineral powder contains SiO ₂ , Al ₂ O ₃ , R ₂ O and Fe ₂ O ₃ , and based on the total weight of the mineral powder, the content of the SiO ₂ is 60-75% by weight, and the content of the Al ₂ O ₃ is 25-40% by weight. The content of R ₂ O is 0.5-2.5% by weight, the content of Fe ₂ O ₃ is 0.5-3.5% by weight, and R is an alkali metal.

Preferably, based on the total weight of the mineral powder, the content of the SiO ₂ is 62.5-66% by weight, the content of the Al ₂ O ₃ is 32-34% by weight, and the content of the R ₂ O It is 1-1.5% by weight, and the content of the Fe ₂ O ₃ is 1-2% by weight.

Preferably, R is sodium or potassium.

Preferably, the content of the glass frit is 40-65 parts by weight relative to 100 parts by weight of the mineral powder; more preferably, the content of the glass frit is 100 parts by weight of the mineral powder 50-60 parts by weight.

Preferably, the amount of the adhesive is such that the viscosity of the uniformly mixed coating composition is 8000-12000 poise; more preferably, the amount of the adhesive is such that the viscosity of the uniformly mixed coating composition It is 10000-11000 poise.

Preferably, the particle size of the glass frit is 0.3 mm or less; more preferably, the particle size of the glass frit is 0.2-0.3 mm.

Preferably, the adhesive is silicate and/or metasilicate; more preferably, the adhesive is metasilicate; further preferably, the metasilicate is metasilicate Sodium.

Preferably, the coating composition further contains additives, further preferably, the additives are boron oxide and/or tin oxide; still further preferably, the additives are relative to 100 parts by weight of the mineral powder The amount used is 1-2 parts by weight.

Preferably, the pH of the composition is 5-8; more preferably, the pH of the composition is 6-7.

The second aspect of the present invention provides a tin oxide electrode coating, which is formed by coating the coating composition provided by the present invention.

A third aspect of the present invention provides a method for protecting a tin oxide electrode, wherein the method includes:

1) The step of applying the coating composition provided by the present invention to the surface of the tin oxide electrode to form a protective coating;

2) The step of melting the protective coating after the tin oxide electrode has risen to the working temperature.

By applying the coating composition provided by the present invention on a tin oxide electrode to obtain a protective coating, not only can the effect of slowly heating the tin oxide electrode be achieved during the baking kiln, but also to protect the tin oxide electrode and thereby protect the electric fluxing equipment At the same time, because the composition of the glass powder in the coating is the same as or similar to the composition of the glass liquid, this ensures that the coating is dissolved into the glass liquid in the later stage of the baking kiln, and is not introduced into the kiln with the process of discharging the furnace charge Other harmful elements.

Other features and advantages of the present invention will be described in detail in the following specific embodiments.

The specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the end points of each range, between the end points of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, These numerical ranges should be considered as specifically disclosed herein.

According to the first aspect of the present invention, the present invention provides a coating composition comprising mineral powder, glass frit and an adhesive, wherein the mineral powder contains SiO ₂ , Al ₂ O ₃ , R ₂ O and Fe ₂ O ₃ , and based on the total weight of the mineral powder, the content of the SiO ₂ is 60-75% by weight, and the content of the Al ₂ O ₃ is 25-40% by weight. The content of R ₂ O is 0.5-2.5% by weight, the content of Fe ₂ O ₃ is 0.5-3.5% by weight, and R is an alkali metal.

In the present invention, in order to further improve the refractoriness and plasticity of the coating composition, preferably, based on the total weight of the mineral powder, the content of the SiO ₂ is 62.5-66% by weight, and the Al ₂ The content of O ₃ is 32-34% by weight, the content of R ₂ O is 1-1.5% by weight, and the content of Fe ₂ O ₃ is 1-2% by weight.

The above R is an alkali metal, and is expressed as one or more of lithium, sodium, potassium, rubidium, cesium, and palladium. Preferably, R is sodium or potassium.

Since the mineral powder has the above-mentioned composition, the mineral powder can have the advantages of high refractoriness and good plasticity. Specifically, the refractoriness can reach 1400-1700°C. In addition, SiO ₂ and Al ₂ O ₃ in the mineral powder are the main components of the liquid crystal substrate, which at the same time ensures that no other harmful elements are introduced into the glass liquid when the subsequent coating is peeled off.

In the present invention, for the consideration of softness and plasticity, the sand quality score of the mineral powder is preferably less than 50%, and more preferably 40-45%.

The particle size of the mineral powder is not particularly limited, but it is usually not less than 100 mesh. Preferably, the particle size of the mineral powder is 100-350 mesh. By selecting mineral powder with the above-mentioned particle size, it is more conducive to smear molding, and further facilitates dissolution and discharge after melting.

In the present invention, for the sake of purity, the whiteness value of the mineral powder is preferably greater than 90%.

In the present invention, from the aspect of adjusting the thickness coefficient, the density of the mineral powder is 2.4-2.6 g/cm ³ , more preferably 2.5-2.6 g/cm ³ .

In the present invention, the refractoriness of the mineral powder is preferably from 1400 to 1700°C, more preferably from 1400 to 1550°C.

In the present invention, preferably, the plasticity index of the mineral powder is greater than 153.6 Kg·cm, more preferably 155-165 Kg·cm.

In the present invention, the type and composition of the glass frit are not particularly limited, and may be various commonly used glass frits in the art, for example, the composition may be: SiO ₂ 71-73% by weight, CaO 6.0-6.5% by weight, MgO 1-4.5% by weight, Al ₂ O ₃ 1.5-2.0% by weight, R ₂ O 14-17% by weight, R is an alkali metal; according to a preferred embodiment of the present invention, the present invention uses TFT glass powder, its composition Can be SiO ₂ 60-63 wt%, Al ₂ O ₃ 17-20 wt%, B ₂ O ₃ 1-4 wt%, MgO 1-4 wt%, CaO 3-6 wt%, SrO 1-4 wt% , BaO 6-9% by weight, ZnO 0-2.5% by weight, R is an alkali metal. Here, also, the above-mentioned R is an alkali metal, and is expressed as one or more of lithium, sodium, potassium, rubidium, cesium, and palladium. Preferably, R is sodium or potassium.

In the present invention, the content of the glass frit is not particularly limited. In order to further satisfy the temperature resistance range of the coating composition at 500-1600° C. and the peeling time of the coating at the baking stage, in the present invention, relative to 100 parts by weight of the mineral powder, the content of the glass powder is 40-65 parts by weight; preferably, relative to 100 parts by weight of the mineral powder, the content of the glass powder is 50-60 parts by weight.

In the present invention, the particle size of the glass frit is not particularly limited, and can be routinely selected by those skilled in the art, but from the perspective of coating peeling time and accelerated decomposition of the coating, in the present invention, the glass frit The particle size is below 0.3mm; preferably, the particle size of the glass frit is 0.2-0.3mm. In the present invention, the glass powder with the above-mentioned particle size is used. When it is melted and detached first, it can drive off the nearby coating in a large area and accelerate the decomposition of the coating.

In the present invention, the adhesive is preferably silicate and/or metasilicate. From the aspect of avoiding the introduction of other harmful elements into the working system, it is preferable that the adhesive is metasilicate.

Examples of the metasilicate may include sodium metasilicate and potassium metasilicate. Because sodium metasilicate is a weather-resistant, strong-adhesive bonding material, and its hardening speed is fast, when the coating composition is applied to the electrode, it can accelerate the formation of the electrode surface coating, which is conducive to shortening the work. Time. Therefore, in the present invention, the metasilicate is preferably sodium metasilicate.

In the present invention, the sodium metasilicate is not particularly limited. In order to further increase the viscosity and bonding strength of the coating composition, it is preferable to use a soluble solid content of 90% or more and a density of 1.43-1.47 at 20°C g/cm ³ , Baume degree °Bé=38-48 sodium metasilicate. The sodium metasilicate can be obtained commercially, for example, it can be sodium metasilicate pentahydrate (Na ₂ SiO ₃ ·5H ₂ O) from Qingdao Darun Chemical Company.

In the coating composition of the present invention, the amount of the adhesive is not particularly limited, and the amount of the adhesive in the present invention is comprehensively considered from the operability during coating and the peeling property after coating The viscosity of the coating composition after uniform mixing is 800-12000 poises; preferably, the amount of the adhesive is such that the viscosity of the coating composition after uniform mixing is 10000-11000 poises. By using the above-mentioned amount of adhesive, it can not only ensure that the electrode slowly heats up without damage during the rapid temperature rise stage, but also ensures the rapid peeling of the coating after the temperature rise is completed. In addition, in the present invention, the viscosity measurement method is measured using the GB2794-81 adhesive viscosity measurement method (rotational viscometer method).

Without affecting the technical effects of the present invention, the composition of the present invention may further contain various additives known in the art. As such an additive, for example, boron oxide and/or tin oxide may be used.

The amount of the above additives is not particularly limited, and may be conventional amounts in the art. For example, the amount of the additive is 1-2 parts by weight relative to 100 parts by weight of the mineral powder.

In the present invention, the pH of the coating composition may be 5-8. From the viewpoint of further reducing the damage of the pH to the tin oxide electrode, the pH of the composition is preferably 6-7.

The invention also provides a tin oxide electrode coating, which is formed by coating the coating composition.

The invention also provides a method for protecting tin oxide electrodes. The method includes:

1) The step of applying the coating composition of the present invention to the surface of the tin oxide electrode to form a protective coating;

2) When the working environment of the tin oxide electrode is raised to the working temperature, the step of melting the protective coating.

In the present invention, the coating method is not particularly limited, and various methods well known to those skilled in the art can be used. For example, coating methods such as brushing, spraying, dipping, spin coating, and pouring can be used. The number of times of application is not particularly limited, and it may be applied once or applied multiple times layer by layer.

The thickness of the formed protective coating is preferably 0.5-3 mm, more preferably 1-2 mm. By making the thickness of the protective coating within the above range, it not only ensures that the electrode slowly heats up without damage during the rapid temperature rise stage, but also ensures the rapid peeling of the coating after the temperature rise is completed.

In the coating protection method of the present invention, the glass powder in the coating composition is not particularly limited, and can be routinely selected by those skilled in the art. It is preferable to use glass frit with the same or similar composition as the glass liquid in the reaction system. In this way, when the baking kiln ends and the temperature in the kiln space reaches the working temperature, the glass frit first melts and dissolves, which causes the electrode coating to decompose and fall off. Enter the kiln without introducing other harmful ingredients into the glass liquid.

1 is a schematic diagram of the state of forming an electrode coating using the coating composition provided by the present invention before the temperature rise is started; FIG. 2 is a schematic diagram of a state where the electrode is pushed into the furnace after the temperature rise is completed; Schematic diagram of the state of electrode coating peeling off. The protection method of the tin oxide electrode of the present invention will be described below with reference to FIGS. 1 to 3.

Specifically, in the hot air baking stage of the electric flux furnace in the manufacture of TFT glass substrates, the protection method provided by the present invention includes:

Step 1) Formulate the coating composition

Dry mix mineral powder and glass powder into a group and put them into a container for homogenization. Then add sodium metasilicate solution to the container and adjust the pH after mixing;

Step 2) Apply tin oxide electrode coating

Insert tin oxide electrode into the electrode hole reserved in the pool wall of the kiln body or the bottom of the pool, the side insertion electrode 1 is opposite to the inside of the pool wall, the depth of the recess is Δx, the bottom insertion electrode 2 is between the bottom surface of the pool bottom The depth of the depression is Δx, and the coating composition solution prepared in step 1) is coated on the side insertion electrode 1 and the bottom insertion electrode 2 in the figure to form a tin oxide electrode with a thickness of Δx as shown in FIG. 1 Coating 3.

Step 3) The coating of the tin oxide electrode falls off

Ignite the kiln flame, and the tin oxide electrode coating directly contacts the flame. Use 3-4 temperature-increasing stages to increase to 1450-1550℃. During trial production, after the tin oxide electrode reaches the normal working temperature, as shown in Figure 2, the electrode is pushed into the kiln to a depth of Δx, so that the electrode surface still unmelted coating fully contacts the glass liquid in the glass pool furnace 4, As shown in Fig. 3, the coating is completely peeled off and dissolved into the pool, and is discharged out of the body together with the glass liquid in the furnace washing stage to complete the heating process of the electric furnace.

When the protection method provided by the present invention is used in the kiln stage of the above TFT glass substrate, the coating thickness of the electrode is not particularly limited to Δx, and Δx can be determined according to actual operation requirements. Considering the heating rate in the final rapid heating stage and the time required for heating, the thickness of the Δx may be 0.5-3 mm, preferably 1-2 mm. By applying the above-mentioned Δx thickness coating, it not only ensures that the electrode slowly heats up without damage during the rapid temperature rise stage, but also ensures the rapid peeling of the coating after the temperature rise is completed.

The present invention will be further described by the following examples, but the present invention is not limited to the following examples.

In the following example, the viscosity measurement method is GB2794-81 Adhesive viscosity measurement method (rotational viscometer method). Preparation Example 1-5 and Preparation Comparative Example 1-2

表2

實施例1Mix 100 mesh quartz powder (SiO ₂ ≥99.2% by weight) with 300 mesh kaolin powder (whiteness ≥90%) and 300 destination open stone powder (whiteness ≥90%) according to the ingredients and contents shown in Table 1, and mix well. Mineral powders K1-K5 and DK1-DK2 were obtained. The sand quality score of the obtained mineral powder, the refractoriness of the mineral powder and the plasticity index of the mineral powder are shown in Table 2. Table 1

Table 2

Example 1

Put the mineral powder and glass powder of Preparation Example 1 into the container according to the ratio shown in Table 3 below to dry mix and stir evenly, then slowly add the sodium metasilicate aqueous solution to the container and mix well to achieve the viscosity shown in Table 3 And adjust the pH to 7. The coating composition C1 is obtained. The composition of the glass powder used is the same as that of the glass liquid in the kiln, the particle size is 0.2mm, and the composition of the composition is specifically SiO ₂ 62% by weight, Al ₂ O ₃ 18% by weight, B ₂ O ₃ 3% by weight, MgO 2% by weight , CaO 4 wt%, SrO 2 wt%, BaO 7 wt%, ZnO 2 wt%. Example 2

Put the mineral powder and glass powder of Preparation Example 2 into the container according to the ratio shown in Table 3 below to dry mix and stir evenly, then slowly add the sodium metasilicate aqueous solution to the container and mix well to achieve the viscosity shown in Table 3 And adjust the pH to 7. The coating composition C2 was obtained. The composition of the glass frit used is the same as that of the glass liquid in the kiln, the particle size is 0.2 mm, and the composition of the composition is the same as that of the glass frit of Example 1. Example 3

Put the mineral powder and glass powder of Preparation Example 3 into the container according to the ratio shown in Table 3 below to dry mix and stir evenly, then slowly add the sodium metasilicate aqueous solution to the container and mix well to achieve the viscosity shown in Table 3 And adjust the pH to 7. The coating composition C3 was obtained. The composition of the glass frit used is the same as that of the glass liquid in the kiln, the particle size is 0.2 mm, and the composition of the composition is the same as that of the glass frit of Example 1. Example 4

Put the mineral powder and glass powder of Preparation Example 4 into the container according to the ratio shown in Table 3 below to dry mix and stir evenly, then slowly add the sodium metasilicate aqueous solution to the container and mix well to achieve the viscosity shown in Table 3 And adjust the pH to 5. Coating composition C4 was obtained. The composition of the glass frit used is the same as that of the glass liquid in the kiln, the particle size is 0.3 mm, and the composition of the composition is the same as that of the glass frit of Example 1. Example 5

Put the mineral powder and glass powder of Preparation Example 5 into the container at the ratio shown in Table 3 below to dry mix and stir well, then slowly add the sodium metasilicate aqueous solution to the container and mix well to achieve the viscosity shown in Table 3 , And adjust the pH to 8. A coating composition C5 was obtained. The composition of the glass frit used is the same as that of the glass liquid in the kiln, the particle size is 0.3 mm, and the composition of the composition is the same as that of the glass frit of Example 1. Example 6

According to the method of Example 1, the difference is that the composition of the glass frit is: SiO ₂ 73 wt%, CaO 6.0 wt%, MgO 4.0 wt%, Al ₂ O ₃ 2.0 wt%, K ₂ O 15 wt%; glass frit The particle size is 0.3mm; potassium metasilicate is used as the adhesive to obtain the coating composition C6. Example 7

According to the method of Example 1, the difference is that the composition of the glass frit is: SiO ₂ 71% by weight, CaO 6.5% by weight, MgO 4.5% by weight, Al ₂ O ₃ 1.5% by weight, K ₂ O 16.5% by weight; the particle size is 0.3mm; using potassium metasilicate as an adhesive to obtain a coating composition C7. Comparative Example 1

The method of Example 1 was followed, except that the mineral powder was replaced with the mineral powder of Comparative Example 1 to obtain a coating composition D1. Comparative Example 2

測試例1-9The method of Example 1 was followed except that the mineral powder was replaced with the mineral powder of Comparative Example 2 to obtain the coating composition D2. table 3

Test Example 1-9

As shown in Fig. 1, insert tin oxide electrode into the electrode hole reserved in the kiln body pool wall or pool bottom masonry, the side insertion electrode 1 is opposite to the inside of the pool wall, the concave depth is Δx, the bottom insertion electrode 2 The depth of the depression with the upper surface of the cell bottom is Δx. In each test example, the coating compositions C1-C7 and D1-D2 prepared in the examples and the comparative examples are applied to the side insertion electrode 1 and the bottom insertion electrode, respectively On 2, a tin oxide electrode coating 3 with a thickness of Δx is formed (tin oxide electrode coatings S1-S7 and DS1-DS2 are obtained respectively), and Δx is shown in Table 4.

The flame of the baking furnace is ignited, and the tin oxide electrode coating 3 directly contacts the flame. In the first stage, the temperature was raised at a rate of 5°C/h for 2d. In the second stage, the temperature was raised at 8°C/h for 5d. In the third stage, the temperature was raised at 12°C/h to 1400°C, as shown in Figure 2. The electrode pushes Δx into the kiln to make the unmelted coating on the surface of the tin oxide electrode fully contact with the glass liquid in the glass bath furnace, so that the electrode coating is completely peeled off (as shown in Figure 3), and the electrode coating is completely recorded The time of exfoliation (ie, the time from when the temperature rise temperature is reached until the electrode coating completely exfoliates) is shown in Table 4. Table 4

It can be seen from Table 4 that the tin oxide electrode coating with S1-S7 coating provided by the present invention can quickly peel off, and no horizontal or vertical cracks are found on the tin oxide electrode after the coating is peeled off, and there is no deformation phenomenon , Tin oxide electrode can work normally. Comparative Example DS1 and DS2 coatings rose to 1000 ℃ in the second stage of the baking kiln, due to the poor bonding performance of the coating, the melting and shedding phenomenon first appeared; in the third stage of rapid heating up period, when the temperature in the kiln reached 1300 ℃, the coating All have fallen off and lost protection. After the coating is peeled off, cracks or even bursts, electrode deformation and other phenomena appear on the electrode, resulting in the electrode not working properly. The coating composition provided by the present invention not only ensures that the electrode is slowly heated without damage during the rapid temperature rising stage, but also realizes the rapid peeling of the coating after the temperature rise is completed.

The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the specific technical features described in the above specific embodiments can be combined in any suitable way without contradictions. In order to avoid unnecessary repetition, the present invention The method will not be explained separately.

In addition, various combinations of various embodiments of the present invention can also be arbitrarily combined, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

1‧‧‧Side insertion electrode 2‧‧‧Bottom insertion electrode 3‧‧‧Electrode protective coating 4‧‧‧Glass bath furnace

FIG. 1 is a schematic diagram of a state where an electrode coating is formed by using the coating composition provided by the present invention before the temperature increase starts. FIG. 2 is a schematic view of the state where the electrode is pushed into the furnace after the temperature rise is completed. FIG. 3 is a schematic diagram of the state in which the electrode coating is peeled off after the temperature increase is completed.

1‧‧‧Side insertion electrode

2‧‧‧Bottom electrode

3‧‧‧electrode protective coating

Claims (17)

A coating composition, characterized in that the coating composition contains mineral powder, glass powder, and an adhesive, wherein the mineral powder contains SiO ₂ , Al ₂ O ₃ , R ₂ O, and Fe ₂ O ₃ , and Based on the total weight of the mineral powder, the content of the SiO ₂ is 60-75% by weight, the content of the Al ₂ O ₃ is 25-40% by weight, and the content of the R ₂ O is 0.5-2.5% by weight. The content of Fe ₂ O ₃ is 0.5-3.5% by weight, and R is an alkali metal; the content of the glass frit is 40-65 parts by weight relative to 100 parts by weight of the mineral powder; the amount of the adhesive is such that after uniform mixing The viscosity of the coating composition is 8000-12000 poise. The coating composition according to item 1 of the patent application scope, wherein, based on the total weight of the mineral powder, the content of the SiO ₂ is 62.5-66% by weight, and the content of the Al ₂ O ₃ is 32-34 The content of the R ₂ O is 1-1.5% by weight, and the content of the Fe ₂ O ₃ is 1-2% by weight. The coating composition as described in item 1 of the patent application, wherein R is sodium or potassium. The coating composition as described in item 1 of the patent application range, wherein the content of the glass frit is 50-60 parts by weight relative to 100 parts by weight of the mineral powder. The coating composition as described in item 1 of the patent application range, wherein the amount of the adhesive is such that the viscosity of the coating composition after uniform mixing is 10000-11000 poises. The coating composition according to any one of claims 1 to 4, wherein the particle size of the glass frit is 0.3 mm or less. The coating composition as described in item 6 of the patent application range, wherein the particle size of the glass frit is 0.2-0.3 mm. The coating composition according to any one of claims 1 to 4, wherein the adhesive is silicate and/or metasilicate. The coating composition as described in item 8 of the patent application range, wherein the adhesive is metasilicate. The coating composition as described in item 8 of the patent application range, wherein the metasilicate is sodium metasilicate. The coating composition according to any one of claims 1 to 4, wherein the coating composition further contains additives. The coating composition as described in item 11 of the patent application range, wherein the additive is boron oxide and/or tin oxide. The coating composition as described in item 12 of the patent application range, wherein the amount of the additive is 1-2 parts by weight relative to 100 parts by weight of the mineral powder. The coating composition according to any one of claims 1 to 4, wherein the pH of the composition is 5-8. The coating composition as described in item 14 of the patent application range, wherein the pH of the composition is 6-7. A tin oxide electrode coating, which is characterized by the first patent application The coating composition described in any one of items 15 to 15 is coated and formed. A method for protecting a tin oxide electrode, comprising: 1) a step of applying the coating composition described in any one of claims 1 to 15 on the surface of a tin oxide electrode to form a protective coating; and 2) The step of melting the protective coating after the tin oxide electrode has risen to the operating temperature.

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