Steel plate enamel high temperature transparent glaze without fluorinated salt and nitrate and its preparation method and application

Abstract

The application discloses a steel plate enamel high-temperature transparent glaze free of fluorinated salt and nitrate, and a preparation method and application thereof, and belongs to the technical field of enamel. The transparent glaze is composed of quartz, zero-water borax, potassium feldspar, fumed silica, titanium dioxide, aluminum oxide, barium carbonate, sodium tripolyphosphate and zinc oxide in a specific mass ratio. The preparation comprises the steps of raw material mixing, high-temperature smelting under pure oxygen condition, wire drawing detection and rapid cooling. The transparent glaze is completely free of fluorinated salt and nitrate, avoids fluorine emission and environmental protection equipment blockage problems from the source, the fluorine content of the product is not detected through detection, meets the requirements of the EU REACH regulation, and simultaneously has good porcelain surface, gloss and firing adaptability, is suitable for a steel plate substrate, has a firing temperature of 840-880 DEG C, and can be used for the production of green and environmentally-friendly enamel products.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of enamel, and particularly relates to a steel plate enamel high-temperature transparent glaze free of fluorinated salt and nitrate salt and a preparation method and application thereof. BACKGROUND

[0002] The steel plate enamel high-temperature transparent glaze needs to be fired at a high temperature (840-880℃) and has no defects in appearance, a smooth porcelain surface and a glossiness of greater than or equal to 80. The traditional formula relies on fluorinated salt (fluorite / fluorosilicate accounts for 1-12%) to achieve fluxing, increase gloss and improve transparency, and the fluorinated salt is not an "optional" additive but an "indispensable" skeleton component in the traditional enamel transparent glaze. Since the fluorinated salt has multiple synergistic effects of reducing the melting temperature, increasing the gloss and improving the stability of the crystal, simply and roughly removing the fluorinated salt does not result in "performance decline" but "collapse" of the entire enamel system. Any fluorine-free attempt must be based on finding or inventing a new substance or new process system that can completely simulate or replace the above multiple functions, and this is still a major technical challenge in the field of enamel technology. Therefore, the importance of fluorinated salt in the traditional process cannot be overemphasized. However, research has shown that:

[0003] 1. Hydrogen fluoride (HF) and silicon tetrafluoride (SiF4) gases released during high-temperature melting process cause damage to health and environment.

[0004] 2. The European Union REACH regulation lists fluorides as substances of very high concern (SVHC), and fluorinated salt products cannot meet the EU REACH regulation requirements for fluorine, with a fluorine (F) limit of 20mg / kg.

[0005] 3. End environmental management equipment is blocked due to fluorinated salt crystallization, which seriously restricts normal production of enterprises.

[0006] At the same time, nitrate salt, as a traditional oxidizing agent and adhesion promoting component, is prone to produce nitrogen oxides (NO x ) during high-temperature decomposition, also facing environmental pressure. Currently, the denitration of enamel glaze has solved the problem of nitrogen oxide emission (such as CN114368912B, CN114315150B, CN114315151B, etc.), and further implementation of fluorine-free and nitrate-free system not only is a necessary choice to respond to regulations, but also is a forward-looking technical layout for the future.

[0007] The replacement of fluorinated salt is a major technical bottleneck at present, mainly reflected in:

[0008] (1) Fluorinated salt dependence is strong, and environmental risk is prominent: CN119710693A (high-temperature-resistant enamel glaze) uses cryolite (Na3AlF6) as a fluxing agent, although it improves temperature resistance, but does not solve the problem of fluorine emission; CN112342544A (low-temperature acid and alkali resistant cast iron enamel) contains sodium fluoride (5-7 parts) in the face glaze formula.

[0009] (2) Non-fluorine substitution scheme has functional defects: CN105800935A (enamel underglaze material) attempts to use lanthanide oxides to enhance adhesion, but it still needs to add 8% fluorine to assist melting, and the high cost of rare earth makes it difficult to promote. CN116854374A (black enamel composite glaze) uses a cobalt-nickel underglaze system, but the anti-explosive agent used contains 8-10% fluorite powder.

[0010] (3) The field of ceramics involves fluorine-free schemes, but it is difficult to apply: CN110885189A relates to a zirconium-free lanolin enamel and a positioning crystal flower ceramic tile made therefrom, CN115626774A relates to a soft light skin ceramic rock plate and a preparation method thereof, CN112979271A relates to a preparation method of a light-weight high-strength pure-color glaze tile, and CN118754723A relates to a hydrophilic self-cleaning antique tile based on phase separation and a preparation method thereof. Although the above-mentioned prior art does not involve the use of fluorinated salt, its technical essence belongs to the field of building ceramic glaze, which is different from the field of enamel underglaze. There are essential differences between ceramic glaze and metal-based enamel glaze in terms of thermal expansion coefficient (the difference in expansion coefficient between the two is one order of magnitude), firing temperature (the firing temperature of ceramic glaze is higher than that of enamel glaze by more than 200°C), and bonding mechanism (the body of ceramic glaze is porcelain clay, while the body of enamel glaze is metal), thus it cannot be directly applied to the field of metal-based enamel.

[0011] In summary, on the basis of denitrification, the problem of defluorination is solved, and the quality of enamel products is improved, which has very important practical significance for promoting the green, low-carbon and high-quality development of the enamel industry. SUMMARY

[0012] In view of the excessive emission of fluorides in the production process of existing enamel glaze, which causes damage to health and the environment, the fluorinated salt-containing products cannot meet the requirements of the EU REACH regulation on fluorine, and the emitted fluorinated salt blocks environmental management facilities, which seriously restricts the normal production of enterprises, the present application provides a steel plate enamel high-temperature transparent glaze without fluorinated salt and nitrate, as well as a preparation method and application thereof.

[0013] The high-temperature transparent enamel for steel plates of the present invention, which is free of fluoride salts and nitrates, is composed of the following components by weight: 19-22 parts quartz, 21-23 parts anhydrous borax, 36-38 parts potassium feldspar, 4-8 parts fumed silica, 4-6 parts titanium dioxide, 6-8 parts alumina, 2-4 parts barium carbonate, 5-7 parts sodium tripolyphosphate, and 1.0-1.5 parts zinc oxide.

[0014] Further, the composition includes 20-22 parts quartz, 21-22 parts anhydrous borax, 36-37 parts potassium feldspar, 5-7 parts fumed silica, 4-5 parts titanium dioxide, 6.5-7.5 parts alumina, 3-4 parts barium carbonate, 5.5-6.5 parts sodium tripolyphosphate, and 1.2-1.4 parts zinc oxide.

[0015] Furthermore, in quartz, the mass percentages of SiO2 and Fe2O3 are: SiO2 ≥ 99% and Fe2O3 ≤ 0.05%; in potassium feldspar, the mass percentage of SiO2 is ≥ 71% and K2O + Na2O ≥ 11%; in titanium dioxide, the mass percentage of TiO2 is: TiO2 ≥ 99%; and zinc oxide is obtained by oxidation after distillation of metallic zinc, with a purity of ≥ 99.7%.

[0016] The preparation method of the above-mentioned high-temperature transparent enamel for steel plates that is free of fluoride salts and nitrates includes the following steps:

[0017] (1) Weigh each component raw material according to the above mass proportions;

[0018] (2) Stir and mix the raw materials described in step (1) until they are evenly mixed;

[0019] (3) Add the mixed material into the melting furnace and melt it under pure oxygen conditions. The melting temperature is controlled at 1300±10℃.

[0020] (4) After the material described in step (3) is completely melted, a borosilicate glass body is obtained. The molten borosilicate glass body is then drilled and quickly drawn into a glass wire of 1.2 to 1.5 meters for testing. The testing requirement is that the glass wire is completely melted within 1 meter.

[0021] (5) The molten borosilicate glass body is rapidly cooled to obtain the product.

[0022] Furthermore, in step (5), the rapid cooling is achieved by water quenching or tableting.

[0023] The above-mentioned application of high-temperature transparent enamel for steel plates that is free of fluoride salts and nitrates is applied to the base enamel of steel plates. The firing temperature of the finished product is 840-880℃, excluding the endpoint value of 840℃.

[0024] The application adds phosphate in the formula of high-temperature transparent glaze of steel plate enamel, provides [PO4] 3- The group promotes nucleation of feldspar, and a eutectic complex fluxing system of'multicomponent carbonate + phosphate + borate' is formed, which strengthens fluxing together with gas-phase silicon dioxide, the introduction of zinc oxide cooperates with titanium dioxide, ZnO / TiO2 reduces the viscosity of liquid phase, and accelerates diffusion of ions and bubbles; the components cooperate to promote improvement of properties such as enamel surface, luster, transparency, and firing performance of transparent glaze.

[0025] The application has the following beneficial effects:

[0026] (1) Fluoride is discharged at an ultra-low standard;

[0027] (2) The product is detected by SGS, and the detection result of fluoride shows that no fluorine is detected, which meets the limit requirement of SVHC (high-concern substance) of the EU REACH regulation.

[0028] (3) The problem of blockage of end environmental protection equipment is solved: the application completely removes fluorine (fluorite, sodium fluorosilicate, etc.), eliminates the fluorine salt crystallization source from the source, and solves the problem of blockage of end environmental protection equipment. According to the actual measurement of the production line, the continuous operation period of the equipment is prolonged from the original 10-15 days to more than 180 days, and the maintenance cost is significantly reduced.

[0029] (4) Good high-temperature firing adaptability: the eutectic complex fluxing system (multicomponent carbonate + phosphate + borate) and the introduction of gas-phase silicon dioxide effectively promote solid-phase reaction, accelerate the melting process from the kinetic point of view, and make the firing temperature stable at 840-880℃, and the enamel surface has good leveling property.

[0030] (5) The addition of phosphate and zinc oxide, the phosphate provides [PO4] 3- The group promotes nucleation of feldspar, and a eutectic complex fluxing system of'multicomponent carbonate + phosphate + borate' is formed, which strengthens fluxing together with gas-phase silicon dioxide, the introduction of zinc oxide cooperates with titanium dioxide, ZnO / TiO2 reduces the viscosity of liquid phase, and accelerates diffusion of ions and bubbles; the components cooperate to promote improvement of properties such as enamel surface, luster, transparency, and firing performance of transparent glaze. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The photo of the enamel plate made of the product obtained in Example 1 of the application. DETAILED DESCRIPTION

[0032] The application will be further described in detail below in combination with specific embodiments, but the application is not limited thereto.

[0033] The equipment used in the embodiments of the application is as follows:

[0034] Ingredients: The full-automatic ingredient mixing system is adopted. The system is fully automatic computer control, and has the characteristics of accurate weighing, uniform mixing and high ingredient efficiency.

[0035] Melting: The automatic feeding system, automatic pure oxygen combustion control system and automatic discharging system are adopted.

[0036] Packaging: The automatic packaging system is adopted.

[0037] The purity of the raw materials used in the embodiment of the application meets the requirements of the industrial grade.

[0038] Example 1

[0039] (1) The raw materials are weighed according to the mass parts of each component as follows:

[0040] Quartz 22 parts, anhydrous borax 21 parts, titanium dioxide 5 parts, fumed silica 4 parts, aluminum oxide 6 parts, barium carbonate 4 parts, potassium feldspar 38 parts, sodium tripolyphosphate 7 parts, and zinc oxide 1.0 part;

[0041] In the quartz, the mass percentage of SiO2 and Fe2O3 is: SiO2≥99%, Fe2O3≤0.05%; in the potassium feldspar, the mass percentage of SiO2 is≥71%, and K2O+Na2O≥11%; in the titanium dioxide, the mass percentage of TiO2 is: TiO2≥99%; the zinc oxide is prepared by distillation of metallic zinc and oxidation, and the mass purity is≥99.7%.

[0042] (2) The above raw materials are stirred and mixed uniformly.

[0043] (3) The mixed material is added to a melting furnace, and is melted under pure oxygen conditions, with the melting temperature controlled at 1300±10℃.

[0044] (4) After the above material is completely melted, a borosilicate glass body is obtained, the molten borosilicate glass body is drilled, and is quickly drawn into a glass filament of 1.2-1.5 meters for detection. The detection requirement is that there is no knot within 1 meter of the glass filament, which means that the melting is completed.

[0045] (5) The melted borosilicate glass body is rapidly cooled (water quenching), and the product is obtained.

[0046] The product obtained in Example 1 of the application is applied to a porcelain enamel plate made of steel plate, and the photo is as shown in Figure 1 The enamel face of the steel plate enamel high-temperature transparent enamel is flat and delicate, the appearance has no obvious defects, the gloss and color performance are excellent, and the product quality meets the enterprise standard requirements.

[0047] Example 2

[0048] The preparation process of this example is basically the same as that of Example 1, except that:

[0049] The mass parts of each component in step (1) are: quartz 19 parts, zero-water borax 23 parts, titanium white 6 parts, fumed silica 8 parts, aluminum oxide 8 parts, barium carbonate 2 parts, potassium feldspar 36 parts, sodium tripolyphosphate 5 parts, and zinc oxide 1.5 parts.

[0050] In step (5), the borosilicate glass body prepared by melting is rapidly cooled by a water quenching process.

[0051] Example 3

[0052] The preparation process of this example is basically the same as that of Example 1, except that:

[0053] The mass parts of each component in step (1) are: quartz 20 parts, zero-water borax 22 parts, titanium white 5 parts, fumed silica 5 parts, aluminum oxide 6.5 parts, barium carbonate 3 parts, potassium feldspar 37 parts, sodium tripolyphosphate 6.5 parts, and zinc oxide 1.2 parts.

[0054] Example 4

[0055] The preparation process of this example is basically the same as that of Example 1, except that:

[0056] The mass parts of each component in step (1) are: quartz 22 parts, zero-water borax 21 parts, titanium white 4 parts, fumed silica 7 parts, aluminum oxide 7.5 parts, barium carbonate 4 parts, potassium feldspar 36 parts, sodium tripolyphosphate 5.5 parts, and zinc oxide 1.4 parts.

[0057] Comparative Example 1

[0058] The rest is the same as Example 1, except that the mass parts of each component in step (1) are: quartz 22.0 parts, zero-water borax 22.0 parts, potassium feldspar 36.0 parts, titanium white 5.6 parts, aluminum oxide 6.2 parts, sodium fluorosilicate 5 parts, and barium carbonate 2.3 parts.

[0059] The test results of the products obtained in the above examples and comparative examples are shown in Table 1 below.

[0060] Table 1 Test results of products obtained in each example and comparative example

[0061]

[0062] The above examples and detection results prove that the enamel high-temperature transparent glaze of the steel plate produced by the method of the application does not contain fluorinated salt and nitrate, no fluorinated salt is generated in the preparation process, and the properties (appearance, porcelain surface, gloss, sintering temperature) of the obtained product meet the requirements of the enamel high-temperature transparent glaze of the steel plate, the fluorinated salt detection result of the product shows that no fluorinated salt is detected, the limit requirement of the SVHC (substance of very high concern) of the European Union REACH regulation is met, and the technical problems of the existing enamel high-temperature transparent glaze of the steel plate in the production process, such as the generation of fluorinated gas emission to pollute the environment and the emission of fluorinated salt to block the environmental protection treatment facilities, are fundamentally solved.

Claims

1. Steel plate enamel high temperature transparent glaze free of fluorinated salts and free of nitrates, characterized in that, Its formula consists of the following components by mass parts: quartz 19-22 parts, zero water borax 21-23 parts, potassium feldspar 36-38 parts, fumed silica 4-8 parts, titanium dioxide 4-6 parts, alumina 6-8 parts, barium carbonate 2-4 parts, sodium tripolyphosphate 5-7 parts, zinc oxide 1.0-1.5 parts.

2. The steel plate enamel high temperature transparent glaze according to claim 1, which is free of fluorinated salts and nitrates, characterized in that, Quartz 20-22 parts, zero water borax 21-22 parts, potassium feldspar 36-37 parts, fumed silica 5-7 parts, titanium dioxide 4-5 parts, alumina 6.5-7.5 parts, barium carbonate 3-4 parts, sodium tripolyphosphate 5.5-6.5 parts, zinc oxide 1.2-1.4 parts.

3. The steel plate enamel high temperature transparent glaze free from fluorinated salts and nitrates according to claim 1 or 2, characterized in that, Zinc oxide is prepared by distillation of metallic zinc followed by oxidation, and its mass purity is ≥99.7%.

4. The steel plate enamel high temperature transparent glaze according to claim 1 or 2, characterized in that, In the quartz, the mass percentage of SiO2 and Fe2O3 is: SiO2≥99%, Fe2O3≤0.05%.

5. The steel plate enamel high temperature transparent glaze according to claim 1 or 2, characterized in that, In the potassium feldspar, the mass percentage of SiO2 is ≥71%, and K2O+Na2O is ≥11%.

6. The steel plate enamel high temperature transparent glaze according to claim 1 or 2, characterized in that, In the titanium dioxide, the mass percentage of TiO2 is: TiO2≥99%.

7. The method of producing a steel plate enamel high temperature transparent glaze free from fluorinated salts and nitrates according to any one of claims 1 to 6, characterized in that, It comprises the following steps: (1) weigh each component raw material; (2) mix the raw materials in step (1) uniformly; (3) add the mixed material to a melting furnace, and melt under pure oxygen conditions, with the melting temperature controlled at 1300±10℃; (4) after the material in step (3) is completely melted, a borosilicate glass body is obtained, the molten borosilicate glass body is tapped, and is quickly drawn into a 1.2-1.5 meter glass filament for detection, with the detection requirement being that there are no nodes within 1 meter of the glass filament, indicating that the melting is complete; (5) quench the melted borosilicate glass body, and the product is obtained.

8. The production method according to claim 7, wherein In step (5), the quenching is by water quenching or tabletting process.

9. Use of a steel sheet according to any one of claims 1 to 6, which is free of fluorinated salts and free of nitrates, for the production of a steel sheet enamel high temperature transparent glaze, characterized in that, When applied to a base glaze with a steel plate as the base body, the firing temperature of the finished product is 840-880℃, and does not include the endpoint value 840℃.

Images