Fluoride-free and nitrate-free steel enamel low temperature transparent glaze, its preparation method and application

Abstract

The application discloses a steel plate enamel low-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, titanium dioxide, sodium tripolyphosphate, barium carbonate, soda ash, potassium feldspar, cerium oxide 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 after detection, meets the requirements of the EU REACH regulation, and simultaneously has good porcelain surface, gloss and low-temperature firing adaptability, is suitable for a steel plate substrate, has a firing temperature of 760-800 DEG C, and can be used for the production of green and environmentally-friendly enamel products.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of enamel, and particularly relates to a steel plate enamel low-temperature transparent glaze without fluorinated salt and nitrate, and a preparation method and application thereof. BACKGROUND

[0002] The steel plate enamel low-temperature transparent glaze needs to meet four core indexes of porcelain surface, gloss (≥80), transparency and low-temperature firing (760-800 DEG C). The traditional formula relies on fluorinated salt (fluorite / fluorosilicate accounts for 1-12%) to achieve fluxing, increase gloss and improve transparency. The fluorinated salt is not an "optional" additive in the traditional enamel transparent glaze, but an "indispensable" skeleton component. Since the fluorinated salt has multiple synergies of reducing the melting temperature, improving the gloss and increasing the stability of the crystal, simply and roughly removing the fluorinated salt does not cause the "decrease" of the performance, but the "collapse" of the entire enamel system. Any fluorine-free attempt must be based on finding or inventing a new material 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 damage to health and 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 due to fluorinated salt crystallization, which seriously restricts normal production of enterprises.

[0006] At the same time, nitrate as a traditional oxidizing agent and close-together promoting component, is easy to produce nitrogen oxides (NO x ) in the high-temperature decomposition process, which also faces 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, promotes the research and development of fluorine-free and nitrate-free system, which 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) 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 low-temperature transparent glaze without fluorinated salt and nitrate, as well as a preparation method and application thereof.

[0013] The steel plate enamel low-temperature transparent glaze without fluorinated salt and nitrate of the present application is prepared by the following steps:

[0014] Further, the mass parts of each component are as follows: quartz 28-30 parts, zero-water borax 20-22 parts, titanium white 3.5-4 parts, sodium tripolyphosphate 5-6 parts, barium carbonate 4-5 parts, soda ash 9-11.5 parts, potassium feldspar 26-27 parts, cerium oxide 0.7-0.8 parts, and zinc oxide 1.8-2.0 parts.

[0015] Further, in the quartz, the mass percentage of SiO2 and Fe2O3 is as follows: SiO2≥99%, and Fe2O3≤0.05%; in the potassium feldspar, the mass percentage of SiO2 and K2O+Na2O is as follows: SiO2≥71%, and K2O+Na2O≥11%; in the titanium white, the mass percentage of TiO2 is as follows: TiO2≥99%; and the zinc oxide is prepared by distillation of metallic zinc and then oxidation, and the mass purity is ≥99.7%.

[0016] The preparation method of the steel plate enamel low-temperature transparent glaze without fluorinated salt and nitrate is as follows:

[0017] (1) the raw materials are weighed according to the above mass parts;

[0018] (2) the raw materials in step (1) are stirred and mixed uniformly;

[0019] (3) the uniformly mixed material is added to a melting furnace, and melting is carried out under pure oxygen conditions, with the melting temperature controlled at 1260±10℃;

[0020] (4) after the material in step (3) is completely melted, a borosilicate glass body is obtained, the molten borosilicate glass body is drawn into a glass filament of 1.2-1.5 meters for detection, and the detection requirement is that there is no knot within 1 meter of the glass filament, indicating that the melting is complete;

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

[0022] Further, in step (5), the rapid cooling is carried out by water quenching or tabletting process.

[0023] The steel plate enamel low-temperature transparent glaze without fluorinated salt and nitrate is applied to a blank with a steel plate as a base body, and the firing temperature of the finished product is 760-800℃.

[0024] The present application adds phosphate in the formula of steel plate enamel low-temperature transparent glaze, provides [PO4] 3- The group promotes the nucleation of feldspar, and a eutectic complex fluxing system of'multielement carbonate + phosphate + borate' is formed to strengthen fluxing, the introduction of zinc oxide cooperates with titanium dioxide, ZnO / TiO2 reduces the viscosity of the liquid phase, accelerates the diffusion of ions and bubbles, a small amount of rare earth metal oxide CeO2 is used to stabilize the lattice defect sites, realize the function of 'lattice repair', enhance the luster and transparency, and the components cooperate to promote the improvement of the performance of the enamel surface, luster, transparency, sintering performance and the like of the transparent glaze.

[0025] The present application has the following beneficial effects:

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

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

[0028] (3) The problem of blockage of the end environmental protection equipment is solved: the present application completely removes the fluoride (fluorite, sodium fluorosilicate, etc.), eliminates the fluoride salt crystallization source from the source, and solves the problem of blockage of the 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 low-temperature sintering adaptability: the eutectic complex fluxing system (multielement carbonate + phosphate + borate) interacts with other components to stably control the sintering temperature at 760-800 DEG C, and the enamel surface has good flowability.

[0030] (5) The addition of phosphate and zinc oxide, the phosphate provides [PO4] 3- The group promotes the nucleation of feldspar, and a eutectic complex fluxing system of'multielement carbonate + phosphate + borate' is formed to strengthen fluxing, the introduction of zinc oxide cooperates with titanium dioxide, ZnO / TiO2 reduces the viscosity of the liquid phase, accelerates the diffusion of ions and bubbles, a small amount of rare earth metal oxide CeO2 is used to stabilize the lattice defect sites, realize the function of 'lattice repair', enhance the luster and transparency, and the components cooperate to promote the improvement of the performance of the enamel surface, luster, transparency, sintering performance and the like of the 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 present application. DETAILED DESCRIPTION

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

[0033] The equipment used in the embodiments of the present 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] 33 parts of quartz, 20 parts of anhydrous borax, 3 parts of titanium white, 3 parts of sodium tripolyphosphate, 3 parts of barium carbonate, 10 parts of soda ash, 26 parts of potassium feldspar, 0.5 parts of cerium oxide and 1.5 parts of zinc oxide;

[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%, K2O+Na2O≥11%; in the titanium white, 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 condition, and the melting temperature is controlled at 1260±10℃.

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

[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 the photo of the enamel plate made of steel plate as shown in Figure 1 The enamel plate made of steel plate does not contain fluorinated salt and nitrate, the enamel surface of the low-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 rest is the same as Example 1, and the difference is that:

[0049] The mass parts of each component in step (1) are: quartz 32 parts, zero-water borax 19 parts, titanium white 2 parts, sodium tripolyphosphate 2 parts, barium carbonate 2 parts, soda ash 12 parts, potassium feldspar 28 parts, cerium oxide 0.6 parts, and zinc oxide 1.0 part.

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

[0051] Example 3

[0052] The rest is the same as example 1, except that:

[0053] The mass parts of each component in step (1) are: quartz 30 parts, zero-water borax 20 parts, titanium white 3.5 parts, sodium tripolyphosphate 5 parts, barium carbonate 4 parts, soda ash 9 parts, potassium feldspar 27 parts, cerium oxide 0.7 parts, and zinc oxide 1.8 parts.

[0054] Example 4

[0055] The rest is the same as example 1, except that:

[0056] The mass parts of each component in step (1) are: quartz 28 parts, zero-water borax 22 parts, titanium white 4 parts, sodium tripolyphosphate 6 parts, barium carbonate 5 parts, soda ash 11.5 parts, potassium feldspar 26 parts, cerium oxide 0.8 parts, and zinc oxide 2 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 28 parts, zero-water borax 22 parts, potassium feldspar 27 parts, soda ash 10.4 parts, sodium fluorosilicate 7 parts, titanium white 3 parts, and fluorite 5.6 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 low-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, the properties (porcelain surface, gloss, transparency, sintering temperature) of the obtained product meet the requirements of the enamel low-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 EU REACH regulation is met, and the technical problems of the existing enamel low-temperature transparent glaze of the steel plate in the production process, i.e. the fluorinated gas emission pollutes the environment and the fluorinated salt emission blocks the environmental protection treatment facilities, are fundamentally solved.

Claims

1. A low-temperature transparent 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: 28-33 parts quartz, 19-22 parts anhydrous borax, 2-4 parts titanium dioxide, 2-6 parts sodium tripolyphosphate, 2-5 parts barium carbonate, 9-12 parts soda ash, 26-28 parts potassium feldspar, 0.5-0.8 parts cerium oxide, and 1-2 parts zinc oxide.

2. The low-temperature transparent enamel glaze for steel plates that is free of fluoride salts and nitrates as described in claim 1, characterized in that, Quartz 28-30 parts, anhydrous borax 20-22 parts, titanium dioxide 3.5-4 parts, sodium tripolyphosphate 5-6 parts, barium carbonate 4-5 parts, soda ash 9-11.5 parts, potassium feldspar 26-27 parts, cerium oxide 0.7-0.8 parts, zinc oxide 1.8-2.0 parts.

3. The low-temperature transparent 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%.

4. The low-temperature transparent 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%.

5. The low-temperature transparent enamel glaze for steel plates that is free of fluoride salts and nitrates as described in claim 1 or 2, characterized in that, In potassium feldspar, the mass percentage of SiO2 is ≥71%, and the mass percentage of K2O+Na2O is ≥11%.

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

7. The method for preparing a low-temperature transparent enamel glaze for steel plates that is free of fluoride salts and nitrates as described in any one of claims 1 to 6, 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 1260±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 completely melted within 1 meter. (5) The molten borosilicate glass body is rapidly cooled to obtain the product.

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

9. The application of the low-temperature transparent enamel glaze for steel plates that is free of fluoride salts and nitrates as described in any one of claims 1 to 6, characterized in that, It is applied to blanks with steel plates as the base material, and the firing temperature of the finished product is 760-800℃.

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