Steel plate enamel low temperature matte enamel without fluorinated salt and without nitrate and its preparation method and application

Abstract

The application discloses a steel plate enamel low-temperature matte glaze free of fluorinated salt and nitrate, and a preparation method and application thereof, and belongs to the technical field of enamel. The matte glaze is prepared from quartz, borax pentahydrate, soda ash, titanium dioxide, magnesium oxide, potassium dihydrogen phosphate, calcium carbonate, zinc oxide, magnesium carbonate, lithium carbonate, aluminum oxide and zirconium silicate according to specific mass proportions. The preparation comprises raw material mixing, melting at 1300±10 DEG C under a pure oxygen environment, and rapid cooling after wire drawing detection of the melting state. The matte glaze completely avoids the use of fluorinated salt and nitrate, eliminates the problems of fluoride emission and environmental protection equipment blockage from the source, the fluorine content of the product is not detected through detection, and the product meets the limit value requirements of the EU REACH regulation. The zinc oxide is newly added, the liquid phase viscosity is reduced by ZnO / TiO2, ion diffusion is accelerated, and the opacity (milk performance) and luster of the enamel glaze are enhanced.

Description

TECHNICAL FIELD

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

[0002] The steel plate enamel low-temperature matte glaze requires low-temperature (760-800) ℃ firing, and has no defects in appearance, a smooth porcelain surface and a gloss (≤10). Fluorinated salt (fluorite / sodium fluorosilicate, 1-15%) is usually added as a fluxing agent and adhesion enhancer in the traditional steel plate enamel low-temperature matte glaze formula. Fluorinated salt is not an "optional" additive in the traditional low-temperature matte glaze, but an "indispensable" skeleton component. Since fluorinated salt has multiple synergistic effects such as reducing the melting temperature, forming an alloy layer by corroding the interface, creating a mechanical anchoring effect, improving opalescence and wettability, simply and roughly removing fluorinated salt is equivalent to removing the load-bearing wall of the building, which does not result in "performance decline", but "collapse" of the entire enamel system. Any attempt to remove fluorinated salt 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 enamel process field. 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 harm to health and the environment.

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

[0005] 3. End environmental management equipment is blocked by 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, and also faces environmental pressure. Currently, the removal of nitrate from enamel glaze has solved the problem of nitrogen oxide emissions (such as CN114368912B, CN114315150B, CN114315151B, etc.), and further implementation of fluorine-free and nitrate-free systems is not only a necessary choice to respond to regulations, but also 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) Strong dependence on fluoride salts and prominent environmental risks: CN119710693A (high temperature resistant enamel glaze) uses cryolite (Na3AlF6) as a flux, which improves the temperature resistance but does not solve the problem of fluorine emission; CN112342544A (low temperature acid and alkali resistant cast iron enamel) contains sodium fluorosilicate (5-7 parts) in its surface glaze formula.

[0009] (2) Non-fluorine alternatives have functional defects: CN105800935A (enamel base glaze material) attempts to enhance adhesion with lanthanide oxides, but it still requires the addition of 8% fluoride to assist melting, and the high cost of rare earth makes it difficult to promote. CN116854374A (black enamel composite glaze) adopts a cobalt-nickel base glaze system, but the explosion retardant it uses contains 8-10% fluorite powder.

[0010] (3) In the ceramics field, there are fluorine-free solutions, but they are difficult to transfer and apply: CN110885189A relates to zirconium-free mutton fat glaze and positioning crystal flower ceramic tiles made using it; CN115626774A relates to soft-light skin-feel ceramic slabs and their preparation methods; CN112979271A relates to the preparation method of lightweight, high-strength, pure-color polished glazed tiles; CN118754723A relates to a hydrophilic self-cleaning antique tile based on phase separation and its preparation method. Although the above-mentioned prior art does not involve the use of fluoride salts, its technical essence belongs to the category of building ceramic glazes, which is a different technical field from enamel base glazes. Ceramic glazes and metal-based enamel glazes have essential differences in thermal expansion coefficients (the two expansion coefficients differ by an order of magnitude), firing temperatures (the firing temperature of ceramic glazes is more than 200℃ higher than that of enamel glazes), and bonding mechanisms (the base of ceramic glazes is porcelain clay, while the base of enamel glazes is metal), thus they cannot be directly transferred and applied to the field of metal-based enamel.

[0011] In summary, addressing the issue of fluoride removal on the basis of nitrate removal, while simultaneously improving the quality of enamel products, is of great practical significance for promoting the green, low-carbon, and high-quality development of the enamel industry. Summary of the Invention

[0012] To address the technical problems of excessive fluoride emissions during existing enamel glaze production processes, which harm health and the environment, the inability of fluoride-containing salt products to meet the EU REACH regulations' requirements for fluoride, and the clogging of environmental protection facilities by emitted fluoride salts, which seriously restricts normal production, this paper provides a low-temperature matte enamel glaze for steel plates that is free of fluoride salts and nitrates, along with its preparation method and applications.

[0013] The present invention provides a low-temperature matte enamel glaze for steel plates that is free of fluoride salts and nitrates. The formula consists of the following components in parts by weight: 28-32 parts quartz, 4-6 parts borax pentahydrate, 16-18 parts soda ash, 4-6 parts titanium dioxide, 13-15 parts magnesium oxide, 2-3 parts potassium dihydrogen phosphate, 2-3 parts calcium carbonate, 4-5 parts zinc oxide, 7-8 parts magnesium carbonate, 1-2 parts lithium carbonate, 1-3 parts aluminum oxide, and 6-8 parts zirconium silicate.

[0014] Further, the composition includes 30-31 parts quartz, 5-5.5 parts borax pentahydrate, 16.5-17 parts soda ash, 4.5-5.2 parts titanium dioxide, 14.3-15 parts magnesium oxide, 2.5-3 parts potassium dihydrogen phosphate, 2.4-3 parts calcium carbonate, 4.5-5 parts zinc oxide, 7.4-8 parts magnesium carbonate, 1.5-2 parts lithium carbonate, 1.6-2.5 parts aluminum oxide, and 6.5-7.5 parts zirconium silicate.

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

[0016] The preparation method of the above-mentioned low-temperature matte enamel glaze 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 drawn into a 1-meter length without any knots. After that, the melting process is completed after 5 to 10 minutes.

[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 aforementioned application of low-temperature matte enamel glaze for steel plates, which is free of fluoride salts and nitrates, is applied to blanks or base glazes with steel plates as the substrate, and the firing temperature of the finished product is 760-800℃.

[0024] Furthermore, by adjusting the composition and amount of the non-fluorinated salt flux in the formulation of this invention, the melting of enamel glaze can be completed as required even without the flux of fluorinated salts. This invention introduces zinc oxide and zirconium silicate into the low-temperature matte glaze formulation of steel plate enamel, and the two work synergistically to enhance the opacification effect of ZnO / ZrO2. The addition of phosphate forms a low eutectic composite flux system of "multi-carbonate + phosphate + borate" to enhance fluxing. The synergistic effect of each component promotes the improvement of various properties of the glaze, such as gloss, opacity, and firing performance.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) Achieve ultra-low emission standards for fluorides.

[0027] (2) The product was tested by SGS and the fluoride test results showed that it was not detected, which meets the EU REACH regulation's limit requirements for SVHC (substances of very high concern).

[0028] (3) The problem of clogging in end-of-line environmental protection equipment is solved: This invention completely removes fluorides (fluorite, sodium fluorosilicate, etc.), eliminating the source of fluoride salt crystallization from the source, thus solving the problem of clogging in end-of-line environmental protection equipment. According to actual production line tests, the continuous operation cycle of the equipment has been extended from the original 10-15 days to more than 180 days, and the maintenance cost has been significantly reduced.

[0029] (4) Good adaptability to low temperature firing: The low eutectic composite flux system (multi-carbonate + phosphate + borate) interacts with other components to keep the firing temperature stable at 760-800℃, and the porcelain surface has good leveling properties.

[0030] (5) Adding zinc oxide and zirconium silicate, the two work together to enhance the opacity effect of ZnO / ZrO2, and ZnO / TiO2 reduces the viscosity of the liquid phase and accelerates ion diffusion. Together with other components, it enhances the opacity (opacity performance) and gloss of the porcelain enamel. Attached Figure Description

[0031] Figure 1 This is a photograph of the product obtained in Embodiment 1 of the present invention applied to a ceramic enamel plate made of steel plate. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited thereto.

[0033] The equipment used in this embodiment of the invention is:

[0034] Ingredient preparation: A fully automated batching and mixing system is used. This system is fully automated and computer-controlled, featuring accurate weighing, uniform mixing, and high batching efficiency.

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

[0036] Packaging: An automated packaging system is used.

[0037] The purity of the raw materials used in the embodiments of this invention meets the requirements of industrial grade.

[0038] Example 1

[0039] (1) Weigh the raw materials according to the following mass parts of each component:

[0040] Quartz 28 parts, borax pentahydrate 4 parts, soda ash 16 parts, titanium dioxide 4 parts, magnesium oxide 13 parts, potassium dihydrogen phosphate 2 parts, calcium carbonate 2 parts, zinc oxide 4 parts, magnesium carbonate 7 parts, lithium carbonate 1 part, aluminum oxide 1 part, zirconium silicate 6 parts.

[0041] In the quartz, the mass percentages of SiO2 and Fe2O3 are: SiO2≥99% and Fe2O3≤0.05%; in the titanium dioxide, the mass percentage of TiO2 is: TiO2≥99%; zinc oxide is obtained by oxidation after distillation of metallic zinc, and its mass purity is ≥99.7%.

[0042] (2) Mix the above raw materials evenly.

[0043] (3) Add the mixed material into the melting furnace and melt it under pure oxygen conditions. The melting temperature is controlled at 1300±10℃.

[0044] (4) After the above materials are completely melted, a borosilicate glass body is obtained. The molten borosilicate glass body is drilled and quickly drawn into a glass wire of 1.2 to 1.5 meters for testing. The testing requirement is: after the glass wire is drawn into 1 meter without knots, continue to melt for 5 minutes to complete the melting.

[0045] (5) Press the molten borosilicate glass into a sheet to obtain the product.

[0046] The product prepared by this invention is applied to a body or base glaze with a steel plate as the substrate, and the firing temperature of the finished product is 760-800℃.

[0047] A photograph of the product obtained in Example 1 of this invention applied to a ceramic enamel printing plate made of steel plate is shown below. Figure 1 As shown, the low-temperature matte enamel glaze for steel plates, which is free of fluoride salts and nitrates, has a good porcelain surface, excellent low-temperature firing performance and matte performance, and is widely used in steel plate one-time enameling products.

[0048] Example 2

[0049] Everything else is the same as in Example 1, except that:

[0050] The mass fractions of each component in step (1) are:

[0051] Quartz 32 parts, borax pentahydrate 6 parts, soda ash 18 parts, titanium dioxide 6 parts, magnesium oxide 15 parts, potassium dihydrogen phosphate 3 parts, calcium carbonate 3 parts, zinc oxide 5 parts, magnesium carbonate 8 parts, lithium carbonate 2 parts, aluminum oxide 3 parts, zirconium silicate 8 parts.

[0052] In step (5), the molten borosilicate glass body is rapidly cooled by water quenching.

[0053] Example 3

[0054] Everything else is the same as in Example 1, except that:

[0055] The mass fractions of each component in step (1) are:

[0056] Quartz 30 parts, borax pentahydrate 5 parts, soda ash 16.5 parts, titanium dioxide 4.5 parts, magnesium oxide 14.5 parts, potassium dihydrogen phosphate 2.5 parts, calcium carbonate 2.4 parts, zinc oxide 4.5 parts, magnesium carbonate 7.4 parts, lithium carbonate 1.5 parts, aluminum oxide 1.6 parts, zirconium silicate 6.5 parts.

[0057] Example 4

[0058] Everything else is the same as in Example 1, except that:

[0059] The mass fractions of each component in step (1) are:

[0060] Quartz 31 parts, borax pentahydrate 5.5 parts, soda ash 17 parts, titanium dioxide 5.2 parts, magnesium oxide 14.3 parts, potassium dihydrogen phosphate 2.6 parts, calcium carbonate 2.4 parts, zinc oxide 4.4 parts, magnesium carbonate 7.2 parts, lithium carbonate 1.7 parts, aluminum oxide 2.5 parts, zirconium silicate 7.5 parts.

[0061] Comparative Example 1

[0062] The rest is the same as in Example 1, except that the mass parts of each component in step (1) are: 28.7 parts of quartz, 6.0 parts of borax pentahydrate, 3.5 parts of titanium dioxide, 8.9 parts of zirconium silicate, 3.5 parts of sodium fluorosilicate, 20.5 parts of soda ash, 1.8 parts of calcium carbonate, 5.7 parts of alumina, 15.8 parts of magnesium carbonate, and 2.8 parts of lithium carbonate.

[0063] The test results of the products obtained from the above embodiments and comparative examples are shown in Table 1 below.

[0064] Table 1. Test results of products obtained from each embodiment and comparative example.

[0065]

[0066] The above embodiments and test results demonstrate that the steel plate enamel low-temperature matte glaze produced by the method of the present invention, which is free of fluoride salts and nitrates, produces no fluorides during the preparation process. After defluorination, the various properties of the resulting product (appearance, porcelain surface, gloss, firing temperature) meet the requirements of steel plate enamel low-temperature matte glaze. The fluoride test results show that no fluoride was detected, which meets the EU REACH regulation's limit requirements for SVHC (substances of very high concern). This fundamentally solves the technical problems of existing steel plate enamel low-temperature matte glazes generating fluoride gas emissions that pollute the environment and the emitted fluoride salts that clog environmental protection facilities during the production process.

Claims

1. A low-temperature matte enamel glaze for steel plates that is free of fluoride salts and nitrates, characterized in that, Its formula consists of the following components by weight: quartz 28-32 parts, borax pentahydrate 4-6 parts, soda ash 16-18 parts, titanium dioxide 4-6 parts, magnesium oxide 13-15 parts, potassium dihydrogen phosphate 2-3 parts, calcium carbonate 2-3 parts, zinc oxide 4-5 parts, magnesium carbonate 7-8 parts, lithium carbonate 1-2 parts, aluminum oxide 1-3 parts, and zirconium silicate 6-8 parts.

2. The low-temperature matte enamel glaze for steel plates that is free of fluoride salts and nitrates as described in claim 1, characterized in that, Quartz 30-31 parts, borax pentahydrate 5-5.5 parts, soda ash 16.5-17 parts, titanium dioxide 4.5-5.2 parts, magnesium oxide 14.3-15 parts, potassium dihydrogen phosphate 2.5-3 parts, calcium carbonate 2.4-3 parts, zinc oxide 4.5-5 parts, magnesium carbonate 7.4-8 parts, lithium carbonate 1.5-2 parts, aluminum oxide 1.6-2.5 parts, zirconium silicate 6.5-7.5 parts.

3. The low-temperature matte enamel glaze for steel plates that is free of fluoride salts and nitrates as described in claim 1 or 2, characterized in that, In quartz, the mass percentages of SiO2 and Fe2O3 are: SiO2 ≥ 99% and Fe2O3 ≤ 0.05%.

4. The low-temperature matte enamel glaze for steel plates that is free of fluoride salts and nitrates as described in claim 1 or 2, characterized in that, The mass percentage of TiO2 in the titanium dioxide is: TiO2≥99%.

5. The low-temperature matte enamel glaze for steel plates that is free of fluoride salts and nitrates as described in claim 1 or 2, characterized in that, Zinc oxide is obtained by oxidizing metallic zinc after distillation, and its purity is ≥99.7%.

6. The method for preparing a low-temperature matte enamel glaze for steel plates that is free of fluoride salts and nitrates as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Weigh the raw materials of each component; (2) Stir and mix the raw materials described in step (1) until they are evenly mixed; (3) Add the mixed material into the melting furnace and melt it under pure oxygen conditions. The melting temperature is controlled at 1300±10℃. (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 drawn into a 1-meter length without any knots. After that, the melting process is completed after 5 to 10 minutes. (5) The molten borosilicate glass body is rapidly cooled to obtain the product.

7. The preparation method according to claim 6, characterized in that, In step (5), the rapid cooling is achieved by water quenching or tableting.

8. The application of the low-temperature matte enamel glaze for steel plates that is free of fluoride salts and nitrates as described in any one of claims 1 to 5, characterized in that, It is applied to blanks or base glazes with steel plates as the base material, and the firing temperature of the finished product is 760-800℃.

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