Cast iron enamel acid-resistant titanium white cover glaze free of fluoride salt and nitrate as well as preparation method and application of cast iron enamel acid-resistant titanium white cover glaze

Abstract

The invention discloses a fluoride-salt-free and nitrate-free cast iron enamel acid-resistant titanium white cover glaze as well as a preparation method and application thereof, and belongs to the technical field of enamel. The titanium dioxide cover glaze is prepared from quartz, borax anhydrous, titanium dioxide, magnesium carbonate, sodium tripolyphosphate, potassium carbonate, lithium carbonate, potassium feldspar and zinc oxide according to a specific mass ratio. The preparation method comprises the steps of raw material mixing, high-temperature melting under a pure oxygen condition, wiredrawing detection, quenching and the like. The titanium white cover glaze is completely free of fluoride salt and nitrate, the problems of fluoride emission and environmental protection equipment blockage are avoided from the source, the fluorine content of the product is not detected through detection, the product meets the requirements of European Union REACH regulations, meanwhile, the titanium white cover glaze has good acid resistance, whiteness, opacification performance and low-temperature firing adaptability and is suitable for cast iron matrixes, the firing temperature ranges from 740 DEG C to 780 DEG C, and the firing cost is low. The method can be used for producing green and environment-friendly enamel products.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of enamel, and particularly relates to a cast iron enamel acid-resistant titanium white face glaze without fluorinated salt and nitrate, and a preparation method and application thereof. BACKGROUND

[0002] The cast iron enamel acid-resistant titanium white face glaze needs to meet four core indexes of acid resistance (≥ A grade), whiteness (≥ 70), high opacity (lactescence performance) and low-temperature firing (740-780℃). The traditional formula relies on fluorinated salt (fluorite / fluorosilicate accounts for 1-12%) to achieve fluxing, improve lactescence performance, etc. Fluorinated salt is not an "optional" additive in traditional enamel face glaze, but an "indispensable" skeleton component. Since fluorinated salt has multiple synergies such as reducing melting temperature, improving opacity and wettability, simply and roughly removing fluorinated salt is equivalent to removing the load-bearing wall of the building, which does not lead to "performance decline", but "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 has so far been 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 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 by fluorinated salt crystallization, seriously restricting normal production of enterprises.

[0006] At the same time, nitrate, 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, promotion of fluorine-free and nitrate-free system research and development 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 tallow enamel and a positioning crystal flower ceramic tile made using the same, CN115626774A relates to a soft light skin ceramic rock plate and a method for preparing the same, CN112979271A relates to a method for preparing 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 method for preparing the same. 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, seriously restricting the normal production of enterprises, the present application provides a cast iron enamel acid-resistant titanium white face glaze without fluorinated salt and nitrate, as well as a preparation method and application thereof.

[0013] The acid-resistant titanium white face glaze for cast iron enamel without fluorinated salt and nitrate of the present application is prepared from the following components by mass fraction: quartz 40-45 parts, zero-water borax 20-25 parts, titanium white 16-20 parts, magnesium carbonate 1-2 parts, sodium tripolyphosphate 2-6 parts, potassium carbonate 3-5 parts, lithium carbonate 2-3 parts, potassium feldspar 2-3 parts, and zinc oxide 1-2 parts.

[0014] Further, the acid-resistant titanium white face glaze for cast iron enamel without fluorinated salt and nitrate of the present application is prepared from the following components by mass fraction: quartz 42-45 parts, zero-water borax 20-22 parts, titanium white 19-20 parts, magnesium carbonate 1.5-2 parts, sodium tripolyphosphate 4.5-6 parts, potassium carbonate 3-4.5 parts, lithium carbonate 2.5-3 parts, potassium feldspar 2.5-3 parts, and zinc oxide 1.2-1.6 parts.

[0015] Further, the acid-resistant titanium white face glaze for cast iron enamel without fluorinated salt and nitrate of the present application is prepared from the following components by mass fraction: quartz 42-45 parts, zero-water borax 20-22 parts, titanium white 19-20 parts, magnesium carbonate 1.5-2 parts, sodium tripolyphosphate 4.5-6 parts, potassium carbonate 3-4.5 parts, lithium carbonate 2.5-3 parts, potassium feldspar 2.5-3 parts, and zinc oxide 1.2-1.6 parts.

[0016] The acid-resistant titanium white face glaze for cast iron enamel without fluorinated salt and nitrate of the present application is prepared from the following components by mass fraction: quartz 42-45 parts, zero-water borax 20-22 parts, titanium white 19-20 parts, magnesium carbonate 1.5-2 parts, sodium tripolyphosphate 4.5-6 parts, potassium carbonate 3-4.5 parts, lithium carbonate 2.5-3 parts, potassium feldspar 2.5-3 parts, and zinc oxide 1.2-1.6 parts.

[0017] (1) the components are weighed according to the above mass fraction;

[0018] (2) the components are stirred and mixed uniformly;

[0019] (3) the uniformly mixed components are added into a melting furnace and melted under pure oxygen condition, and the melting temperature is controlled at 1300±10℃;

[0020] (4) after the components are completely melted, a borosilicate glass body is obtained, the melted borosilicate glass body is struck, and is quickly drawn into a glass filament of 1.2-1.5 meters for detection, and the detection requirement is that the glass filament is continuously melted for 20-25 minutes without node within 1 meter of the glass filament, and the melting is completed;

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

[0022] Further, in step (5), the rapid cooling is achieved by water quenching or tablet pressing process.

[0023] The acid-resistant titanium white face glaze for cast iron enamel without fluorinated salt and nitrate of the present application is applied to a blank with cast iron as the base body, and the firing temperature of the finished product is 740-780℃.

[0024] The application increases the amount of titanium dioxide and zinc oxide in the cast iron enamel acid-resistant titanium dioxide face glaze formula, strengthens the synergistic effect of zinc oxide and titanium dioxide, reduces the liquid phase viscosity of ZnO / TiO2, increases the whiteness, increases the amount of phosphate, on the one hand, the phosphate provides [PO4] 3- group promotes feldspar nucleation, and on the other hand, forms a low eutectic complex fluxing system of "multinary carbonate + phosphate + borate" to strengthen fluxing, and the components jointly act to improve the gloss, whiteness, opacity (lactescence performance) and firing performance of the porcelain enamel surface.

[0025] The 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 it is not detected, which meets the limit value requirement of the SVHC (substance of very high concern) of the EU REACH regulation.

[0028] (3) The end environmental protection equipment blockage problem is solved: the application completely removes fluoride (fluorite, sodium fluorosilicate, etc.), eliminates the fluorine salt crystallization source from the source, and solves the end environmental protection equipment blockage problem. 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 firing adaptability: the low eutectic complex fluxing system (multinary carbonate + phosphate + borate) interacts with other components to stably control the firing temperature at 740-780℃, and the porcelain surface has good leveling property.

[0030] (5) Increasing the amount of phosphate, the phosphate provides [PO4] 3- group promotes feldspar nucleation, increasing the amount of titanium dioxide and zinc oxide, strengthening the synergistic effect of zinc oxide and titanium dioxide, reducing the liquid phase viscosity of ZnO / TiO2, improving the whiteness, and the components jointly act to improve the gloss, whiteness, opacity (lactescence performance) and firing performance of the porcelain enamel surface. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The photo of the porcelain enamel plate made of cast iron using 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 examples of the application is as follows:

[0034] Batching: using automatic batching, mixing system. The system is fully automated computer control, with accurate weighing, uniform mixing, high efficiency of batching characteristics.

[0035] Melting: using automatic feeding system, automatic pure oxygen combustion control system, automatic discharge system.

[0036] Packaging: using automatic packaging system.

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

[0038] Example 1

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

[0040] Quartz 43 parts, zero water borax 23 parts, titanium dioxide 18 parts, magnesium carbonate 2 parts, sodium tripolyphosphate 3.8 parts, potassium carbonate 4 parts, lithium carbonate 2.2 parts, potassium feldspar 2.5 parts, zinc oxide 2 parts;

[0041] The mass fraction of SiO2 in quartz is ≥99%, the mass fraction of SiO2 in potassium feldspar is ≥71%, K2O+Na2O is ≥11%, the mass fraction of TiO2 in titanium dioxide is ≥99%, and the mass purity of zinc oxide prepared by distillation of metallic zinc and oxidation is ≥99.7%.

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

[0043] (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 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 1.2-1.5 meter glass filament for detection, the detection requirement is: no knot within 1 meter of the glass filament continues to melt for 20 minutes, which is the completion of melting.

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

[0046] The product obtained in Example 1 is applied to a porcelain enamel plate made of cast iron, as shown in Figure 1 The cast iron enamel enamel with no fluorinated salt and no nitrate has high flatness, gloss and whiteness, acid resistance A and above, high expansion coefficient, and is suitable for enameling of cast iron blanks.

[0047] Example 2

[0048] The rest is the same as Example 1, except that:

[0049] The mass parts of the components in step (1) are: quartz 40 parts, zero-water borax 25 parts, titanium white 16 parts, magnesium carbonate 1 part, sodium tripolyphosphate 2 parts, potassium carbonate 5 parts, lithium carbonate 2 parts, potassium feldspar 2 parts, and zinc oxide 1 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 in Example 1, except that:

[0053] The mass parts of the components in step (1) are: quartz 42 parts, zero-water borax 22 parts, titanium white 19 parts, magnesium carbonate 1.5 parts, sodium tripolyphosphate 4.5 parts, potassium carbonate 4.5 parts, lithium carbonate 2.5 parts, potassium feldspar 2.5 parts, and zinc oxide 1.6 parts.

[0054] Example 4

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

[0056] The mass parts of the components in step (1) are: quartz 45 parts, zero-water borax 20 parts, titanium white 20 parts, magnesium carbonate 2 parts, sodium tripolyphosphate 6 parts, potassium carbonate 3 parts, lithium carbonate 3 parts, potassium feldspar 3 parts, and zinc oxide 1.2 parts.

[0057] Comparative Example 1

[0058] The rest is the same as in Example 1, except that: the mass parts of the components in step (1) are: quartz 44.0 parts, zero-water borax 25.0 parts, cobalt oxide 0.02 parts, titanium white 16.5 parts, magnesium carbonate 2.6 parts, sodium tripolyphosphate 1.2 parts, sodium fluosilicate 7 parts, and aluminum oxide 2.2 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 the products obtained in the examples and comparative examples

[0061]

[0062] The above examples and detection results prove that the cast iron enamel acid-resistant titanium white face glaze 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 (acid resistance, whiteness, gloss, opacity, sintering temperature) of the obtained product meet the requirements of cast iron enamel acid-resistant titanium white face glaze, the fluorinated salt detection result of the product shows that no fluorinated salt is detected, the limit requirement of SVHC (substance of very high concern) of the European Union REACH regulation is met, and the technical problems of environmental pollution caused by fluorinated gas emission and fluorinated salt emission in the production process of the existing cast iron enamel acid-resistant titanium white face glaze and the blocking of environmental protection treatment facilities are fundamentally solved.

Claims

1. A cast iron enamel acid-resistant titanium white glaze that is free of fluoride salts and nitrates, characterized in that, Its formula consists of the following components by weight: quartz 40-45 parts, anhydrous borax 20-25 parts, titanium dioxide 16-20 parts, magnesium carbonate 1-2 parts, sodium tripolyphosphate 2-6 parts, potassium carbonate 3-5 parts, lithium carbonate 2-3 parts, potassium feldspar 2-3 parts, and zinc oxide 1-2 parts.

2. The cast iron enamel acid-resistant titanium white glaze that is free of fluoride salts and nitrates according to claim 1, characterized in that, Quartz 42-45 parts, anhydrous borax 20-22 parts, titanium dioxide 19-20 parts, magnesium carbonate 1.5-2 parts, sodium tripolyphosphate 4.5-6 parts, potassium carbonate 3-4.5 parts, lithium carbonate 2.5-3 parts, potassium feldspar 2.5-3 parts, zinc oxide 1.2-1.6 parts.

3. The cast iron enamel acid-resistant titanium white glaze that is free of fluoride salts and nitrates according to claim 1 or 2, characterized in that, The mass percentage of SiO2 in quartz is ≥99%.

4. The cast iron enamel acid-resistant titanium white glaze that is free of fluoride salts and nitrates according to claim 1 or 2, characterized in that, The mass percentage of SiO2 in potassium feldspar is ≥71%, and the mass percentage of K2O+Na2O is ≥11%.

5. The cast iron enamel acid-resistant titanium white glaze that is free of fluoride salts and nitrates according to claim 1 or 2, characterized in that, In titanium dioxide, TiO2 accounts for ≥99% by mass.

6. The cast iron enamel acid-resistant titanium white glaze that is free of fluoride salts and nitrates according to claim 1 or 2, characterized in that, Zinc oxide is obtained by oxidizing metallic zinc after distillation, and its purity is ≥99.7%.

7. The method for preparing an acid-resistant titanium dioxide cast iron enamel glaze 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 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 melted without knots within 1 meter for 20 to 25 minutes to complete the melting process. (5) The molten borosilicate glass body is rapidly cooled to obtain the product.

8. The preparation method according to claim 7, characterized in that, The rapid cooling described in step (5) is a process using water quenching or tableting.

9. The application of the cast iron enamel titanium white glaze 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 cast iron as the base material, and the firing temperature of the finished product is 740-780℃.

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