Steel plate enamel for medium temperature acid-resistant semi-transparent glaze without fluorinated salt and nitrate and its preparation method and application

Abstract

The application discloses a steel plate enamel mid-temperature acid-resistant translucent glaze free of fluorinated salt and nitrate, a preparation method and application thereof, and belongs to the technical field of enamel. The translucent glaze is composed of quartz, zero-water borax, titanium white, trisodium phosphate, potassium carbonate, lithium carbonate, aluminum oxide, zinc oxide and soda ash 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 translucent 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, has good porcelain surface, gloss and firing adaptability, is suitable for a steel plate substrate, has a firing temperature of 800-840 DEG C, and can be used for the production of green and environment-friendly enamel products.

Description

Technical Field

[0001] This invention belongs to the field of enamel technology, specifically relating to a low-temperature acid-resistant semi-transparent enamel glaze for steel plates that is free of fluoride salts and nitrates, its preparation method, and its application. Background Technology

[0002] The medium-temperature acid-resistant translucent enamel glaze for steel plates must simultaneously meet the requirements of acid resistance (≥ Grade A), medium-temperature firing (≤800-840℃), and have a defect-free appearance, a smooth surface, and a gloss level ≥80. Traditional formulations rely on fluoride salts (fluorite / fluorosilicate ratio 1-12%) to achieve fluxing, increase gloss, and improve transparency. Fluoride salts are not "dispensable" additives in traditional enamel base glazes, but rather "indispensable" skeletal components. Given that fluoride salts have multiple synergistic effects, such as lowering melting temperature, increasing gloss, and increasing crystal stability, simply and crudely removing fluoride salts will not lead to a "decrease" in performance, but rather a "collapse" of the entire enamel system. Any attempt at fluorination-free enamel must be based on finding or inventing a new material or process system that can completely simulate or replace the above-mentioned multiple functions, which remains a major technical challenge in the field of enamel technology. Therefore, the importance of fluoride salts in traditional processes cannot be overstated. However, research confirms:

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

[0004] 2. The EU REACH regulation lists fluorides as Substances of Very High Concern (SVHC). Fluoride salt products cannot meet the EU REACH regulations' requirements for fluoride, with a fluoride (F) limit of 20 mg / kg.

[0005] 3. The end-of-pipe environmental treatment equipment is blocked by fluoride crystals, which seriously restricts the normal production of enterprises.

[0006] Meanwhile, nitrates, as traditional oxidants and adhesion promoters, readily produce nitrogen oxides (NOx) during high-temperature decomposition. x Similarly, they also face environmental pressures. Currently, the removal of nitrates from enamel glazes has solved the problem of nitrogen oxide emissions (such as CN114368912B, CN114315150B, CN114315151B, etc.). Further achieving fluorine-free production and promoting the research and development of fluorine-free and nitrate-free systems is not only an inevitable choice to comply with regulations, but also a forward-looking technological layout for the future.

[0007] The replacement of fluoride salts is a major technological 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 (medium temperature acid and alkali resistant steel plate enamel) contains sodium fluorosilicate (5-7 parts) in its semi-transparent glaze formula.

[0009] (2) Non-fluorine alternatives have functional defects: CN105800935A (enamel 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) uses 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] In response to the technical problems of excessive fluoride emissions during the existing enamel glaze production process, which cause harm to health and the environment, the inability of fluoride-containing salt products to meet the fluoride requirements of the EU REACH regulation, and the clogging of environmental protection facilities by emitted fluoride salts, which seriously restricts the normal production of enterprises, this invention provides a medium-temperature acid-resistant semi-transparent enamel glaze for steel plates that is free of fluoride salts and nitrates, as well as its preparation method and application.

[0013] The present invention relates to a medium-temperature acid-resistant translucent enamel for steel plates that is free of fluoride salts and nitrates. Its formula consists of the following components in parts by weight: quartz 43-46 parts, anhydrous borax 25-29 parts, titanium dioxide 5-7 parts, trisodium phosphate 2-4 parts, potassium carbonate 4-6 parts, lithium carbonate 2-4 parts, alumina 1-3 parts, zinc oxide 2-4 parts, and soda ash 6-9 parts.

[0014] Further, the composition includes 44-46 parts quartz, 25-27 parts anhydrous borax, 5-6 parts titanium dioxide, 2-3 parts trisodium phosphate, 4-5 parts potassium carbonate, 2.5-3.5 parts lithium carbonate, 1.5-2.5 parts alumina, 3-4 parts zinc oxide, and 7-9 parts soda ash.

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

[0016] The preparation method of the above-mentioned medium-temperature acid-resistant translucent 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 drilled and quickly drawn into a glass wire of 1.2 to 1.5 meters for testing. The testing requirement is: the glass wire is melted without knots within 1 meter for 10 to 15 minutes to complete the melting process.

[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 medium-temperature acid-resistant semi-transparent enamel for steel plates, which is free of fluoride salts and nitrates, is applied to blanks with steel plates as the base material. The firing temperature of the finished product is 800-840℃, excluding the endpoint value of 800℃.

[0024] This invention introduces zinc oxide into the medium-temperature acid-resistant translucent glaze formulation of steel plate enamel. The zinc oxide works synergistically with the titanium dioxide in titanium dioxide, and the ZnO / TiO2 reduces the viscosity of the liquid phase and accelerates the diffusion of ions and bubbles. The eutectic composite fluxing system of "multi-carbonate + phosphate + borate" strengthens the fluxing process. The synergistic effect of each component promotes the improvement of various properties of the medium-temperature acid-resistant transparent glaze of steel plate enamel, such as the surface finish, gloss, acid resistance, transparency, 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 medium temperature firing: The low eutectic composite flux system (multi-carbonate + phosphate + borate) interacts with other components to keep the firing temperature stable at 800-840℃, and the porcelain surface has good leveling properties.

[0030] (5) Adding zinc oxide, which works synergistically with TiO2 in titanium dioxide, reduces the viscosity of the liquid phase and accelerates ion diffusion. Together with other components, it promotes the improvement of various properties of medium-temperature acid-resistant translucent glaze, such as surface finish, gloss, acid resistance, transparency, and firing performance. 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 printing 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 43 parts, anhydrous borax 29 parts, titanium dioxide 7 parts, trisodium phosphate 4 parts, potassium carbonate 4 parts, lithium carbonate 4 parts, soda ash 7 parts, alumina 3 parts, zinc oxide 2 parts.

[0041] The mass percentage of SiO2 in quartz is ≥99%, the mass percentage of TiO2 in titanium dioxide is ≥99%, and zinc oxide is obtained by oxidation after distillation of metallic zinc, with a mass purity of ≥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: the glass wire is melted without knots for 10 minutes to complete the melting.

[0045] (5) The molten borosilicate glass body is rapidly cooled (water quenched) to obtain the product.

[0046] 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 steel plate enamel medium-temperature acid-resistant semi-transparent glaze, which is free of fluoride salts and nitrates, has a smooth and delicate surface, no obvious defects in appearance, excellent gloss and color development performance, and acid resistance of A or above. The product quality meets the enterprise's standard requirements.

[0047] Example 2

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

[0049] The mass fractions of each component in step (1) are: 45 parts quartz, 28 parts anhydrous borax, 6 parts titanium dioxide, 3 parts trisodium phosphate, 6 parts potassium carbonate, 2 parts lithium carbonate, 8 parts soda ash, 3 parts zinc oxide, and 2 parts aluminum oxide.

[0050] In step (5), the molten borosilicate glass body is rapidly cooled by pressing.

[0051] Example 3

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

[0053] The mass fractions of each component in step (1) are: 44 parts quartz, 25 parts anhydrous borax, 6 parts titanium dioxide, 2 parts trisodium phosphate, 5 parts potassium carbonate, 2.5 parts lithium carbonate, 1.5 parts aluminum oxide, 4 parts zinc oxide, and 9 parts soda ash.

[0054] Example 4

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

[0056] The mass fractions of each component in step (1) are: 46 parts quartz, 27 parts anhydrous borax, 5 parts titanium dioxide, 3 parts trisodium phosphate, 4 parts potassium carbonate, 3.5 parts lithium carbonate, 2.5 parts aluminum oxide, 3 parts zinc oxide, and 7 parts soda ash.

[0057] Comparative Example 1

[0058] The rest is the same as in Example 1, except that the mass parts of each component in step (1) are: quartz 46.0 parts, anhydrous borax 29.0 parts, soda ash 2.1 parts, sodium fluorosilicate 5.9 parts, titanium dioxide 6.1 parts, lithium carbonate 2.2 parts, and alumina 2.0 parts.

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

[0060] Table 1. Test results of products obtained from each embodiment and comparative example.

[0061]

[0062] The above embodiments and test results demonstrate that the medium-temperature acid-resistant semi-transparent enamel glaze for steel plates produced by the method of the present invention, which is free of fluoride salts and nitrates, produces no fluorides during the preparation process. The various properties of the resulting product (appearance, porcelain surface, acid resistance, transparency, gloss, firing temperature) all meet the requirements for acid-resistant semi-transparent enamel glazes for steel plates. The fluoride test results show that no fluoride was detected, which meets the limit requirements of the EU REACH regulation for SVHC (substances of very high concern). This fundamentally solves the technical problems of existing medium-temperature acid-resistant semi-transparent enamel glazes for steel plates generating fluoride gas emissions that pollute the environment and the fluoride salts emitted that clog environmental protection facilities during the production process.

Claims

1. A medium-temperature acid-resistant translucent enamel for steel plates that is free of fluoride salts and nitrates, characterized in that, Its formula consists of the following components by weight: quartz 43-46 parts, anhydrous borax 25-29 parts, titanium dioxide 5-7 parts, trisodium phosphate 2-4 parts, potassium carbonate 4-6 parts, lithium carbonate 2-4 parts, alumina 1-3 parts, zinc oxide 2-4 parts, and soda ash 6-9 parts.

2. The medium-temperature acid-resistant translucent enamel for steel plates that is free of fluoride salts and nitrates as described in claim 1, characterized in that, Quartz 44-46 parts, anhydrous borax 25-27 parts, titanium dioxide 5-6 parts, trisodium phosphate 2-3 parts, potassium carbonate 4-5 parts, lithium carbonate 2.5-3.5 parts, alumina 1.5-2.5 parts, zinc oxide 3-4 parts, soda ash 7-9 parts.

3. The medium-temperature acid-resistant translucent enamel 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 SiO2 in quartz is ≥99%.

4. The medium-temperature acid-resistant translucent enamel for steel plates that is free of fluoride salts and nitrates as described in claim 1 or 2, characterized in that, In titanium dioxide, TiO2 accounts for ≥99% by mass.

5. The medium-temperature acid-resistant translucent enamel 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 medium-temperature acid-resistant translucent enamel 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 drilled and quickly drawn into a glass wire of 1.2 to 1.5 meters for testing. The testing requirement is: the glass wire is melted without knots within 1 meter for 10 to 15 minutes to complete the melting process. (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 medium-temperature acid-resistant translucent enamel for steel plates as described in any one of claims 1 to 5, characterized in that, It is applied to blanks with steel plates as the base material, and the firing temperature of the finished product is 800-840℃, excluding the endpoint value of 800℃.

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