Red glaze coloring agent for magnesium reinforced porcelain as well as preparation method and application of red glaze coloring agent

Abstract

The invention discloses a magnesium reinforced porcelain red underglaze coloring agent as well as a preparation method and application thereof, and belongs to the technical field of underglaze coloring agents. The magnesium reinforced porcelain red underglaze coloring agent comprises the following solid components in percentage by weight: 65-70% of potassium feldspar, 4-5% of calcined zinc oxide, 3-4% of zirconium silicate, 0.9-1.2% of methyl cellulose and 20-26% of wrapping red pigment, wherein the weight content of K2O in the potassium feldspar is 10-12%. The magnesium reinforced porcelain red underglaze coloring agent is applied to a magnesium reinforced porcelain green body, the glaze surface glossiness is high, and the color is pure and full.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underglaze colorant, and particularly relates to a magnesium reinforced porcelain red underglaze colorant and a preparation method and application thereof. BACKGROUND

[0002] Daily-use porcelain is a kind of porcelain used in daily life. Common daily-use porcelain is usually made of feldspar, quartz and kaolin as main raw materials. When decorated, the low-temperature color baking and high-temperature glazing process is adopted. The body is stable to the color development of underglaze colorant and easy to realize. However, the whiteness and strength of common porcelain devices are poor, and the devices are not resistant to impact and are easily damaged in use.

[0003] The daily-use porcelain made of magnesium reinforced porcelain has high whiteness, good light transmittance and high strength. However, the body contains a large amount of magnesium oxide, which is not friendly to the color development of underglaze colorant, especially for red color system, which inhibits the color development of red color and even causes color fading. Generally, the red underglaze colorant applied to magnesium reinforced porcelain is prone to orange glaze and pinhole defects, and the yield is extremely low. Therefore, the decoration of magnesium reinforced porcelain on the market is mostly white body with decals, which cannot improve the added value of the product and cannot perfectly display the advantages of magnesium reinforced porcelain as a high-end porcelain.

[0004] Therefore, it is of great significance to provide a red underglaze colorant suitable for magnesium reinforced porcelain for preparing high-end magnesium reinforced porcelain. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the application provides a magnesium reinforced porcelain red underglaze colorant and a preparation method and application thereof. The magnesium reinforced porcelain red underglaze colorant of the application is applied to the body of magnesium reinforced porcelain, and the glaze has high gloss, pure and full color.

[0006] The technical scheme adopted by the application to solve the technical problems is:

[0007] The application provides a magnesium reinforced porcelain red underglaze colorant, which comprises the following components in percentage by weight:

[0008] 65-70% of potassium feldspar, 4-5% of calcined zinc oxide, 3-4% of zirconium silicate, 0.9-1.2% of methyl cellulose and 20-26% of red material wrapped.

[0009] The weight content of K2O in the potassium feldspar is 10-12%.

[0010] Preferably, the wrapped red material is zirconium silicate wrapped cadmium selenium red material.

[0011] Preferably, the chemical composition of the potassium feldspar is SiO2: 60-70%, Al2O3: 15-20%, CaO: 0.2-0.5%, K2O: 10-12%, Na2O: 2-3%, and the balance is other components.

[0012] Preferably, the magnesium reinforced porcelain red underglaze colorant further comprises water, and the weight ratio of solid components to water is 100: 150-170.

[0013] Preferably, the magnesium reinforced porcelain red underglaze colorant has a specific gravity of 1.32-1.35 g / ml and a flow rate of 38-48 s / 100 ml.

[0014] The application provides a preparation method of the magnesium reinforced porcelain red underglaze colorant.

[0015] S1: ball milling the potassium feldspar and half of the methyl cellulose in the formula with water;

[0016] S2: adding calcined zinc oxide, zirconium silicate, red material, the remaining half of the methyl cellulose in the formula, and water, and continuing to ball mill, discharging, sieving, and removing iron to obtain the magnesium reinforced porcelain red underglaze colorant.

[0017] Preferably, in step S1, the weight ratio of the potassium feldspar and half of the methyl cellulose to water in the ball milling is 100: 150-170.

[0018] Preferably, in step S1, the ball milling time is 12-15 h.

[0019] Preferably, in step S1, the ball milling time is 12-15 h.

[0020] Preferably, in step S2, the mass ratio of the total mass of the calcined zinc oxide, zirconium silicate, red material, and remaining half of the methyl cellulose to the mass of water is 100: 150-170.

[0021] Preferably, in step S2, the ball milling time is 4-6 h.

[0022] Preferably, in step S2, the sieving is performed through a 150-180 mesh sieve.

[0023] The application provides a red underglaze color magnesium reinforced porcelain, which comprises a magnesium reinforced porcelain body, a red underglaze color layer, and a protective glaze layer.

[0024] Preferably, the weight content of MgO in the magnesia reinforced porcelain body is above 22%;

[0025] Further preferably, the components of the magnesia reinforced porcelain body are SiO2: 61-63%, Al2O3: 4-5%, CaO: 2-3%, MgO: 22-24%, K2O: 0.5-1%, Na2O: 0.2-0.5%, and the balance is other ingredients.

[0026] More preferably, the components of the magnesia reinforced porcelain body are SiO2: 62.8%, Al2O3: 4.9%, CaO: 2.6%, MgO: 22.1%, K2O: 0.82%, Na2O: 0.3%, and the balance is other ingredients.

[0027] Preferably, the protective glaze layer is prepared from a low-temperature frit glaze with boric oxide as the main flux.

[0028] Further preferably, the components of the low-temperature frit glaze are SiO2: 53-55%, Al2O3: 10-12%, CaO: 8-9%, MgO: 0.5-1%, K2O: 3-4%, Na2O: 2-3%, ZnO: 1.5-2%, Li2O: 1.5-2%, B2O3: 10-12%, and the balance is other ingredients.

[0029] More preferably, the components of the low-temperature frit glaze are SiO2: 54.6%, Al2O3: 11.8%, CaO: 8.5%, MgO: 0.7%, K2O: 3.4%, Na2O: 2.4%, ZnO: 1.9%, Li2O: 1.9%, B2O3: 11.8%, and the balance is other ingredients.

[0030] The present application provides a preparation method of the above-mentioned magnesia reinforced porcelain red underglaze color, comprising the following steps:

[0031] (1) low-temperature biscuit firing of the magnesia reinforced porcelain body;

[0032] (2) spraying color on the low-temperature biscuit fired magnesia reinforced porcelain body with a magnesia reinforced porcelain red underglaze colorant, then high-temperature baking color, polishing and cleaning, drying, and cooling to obtain a magnesia reinforced porcelain red color body;

[0033] (3) glazing, shadow drying, and glaze firing of the magnesia reinforced porcelain red color body to obtain a magnesia reinforced porcelain red underglaze color finished product.

[0034] Preferably, the temperature of the low-temperature biscuit firing in step (1) is 960-980℃, the time is 8-10 hours, and the atmosphere is oxidizing atmosphere;

[0035] Preferably, the low-temperature biscuit fired magnesia reinforced porcelain body is rotated during the spraying color process in step (2).

[0036] Preferably, the thickness of the spraying in step (2) is 0.15-0.3mm;

[0037] Preferably, the temperature of the high-temperature baking in step (2) is 1280±5℃, the time is 12-15 hours, and the atmosphere is oxidizing atmosphere;

[0038] Preferably, the time of the drying in step (2) is 3-5 hours;

[0039] Preferably, the cooling in step (2) is natural cooling under room temperature air;

[0040] Preferably, the glazing in step (3) is performed while rotating the magnesia reinforced porcelain red body;

[0041] Preferably, the thickness of the glazing in step (3) is 0.2-0.4mm;

[0042] Preferably, the air drying in step (3) is natural air drying under room temperature air;

[0043] Preferably, the glazing firing in step (3) is performed at a temperature of 1110-1130℃ for 10-12 hours in oxidizing atmosphere.

[0044] The magnesia reinforced porcelain red underglaze colorant of the present application is completely suitable for magnesia reinforced porcelain, and the adopted process is high-temperature baking and low-temperature glazing firing. After glazing firing, the obtained product has bright and lustrous glaze surface and bright and full color. The present application fills the blank of red underglaze color for magnesia reinforced porcelain. The underglaze color process is mainly used because the underglaze color has the excellent characteristics of bright and full color, never fading, green, healthy and non-toxic. The high-potassium feldspar added in the fluxing agent can help to wrap the red color, promote the formation of stable intermediate layer between the body and the colorant, and the addition of a small amount of calcined zinc oxide can avoid the appearance of pinholes on the glaze surface. The zirconium silicate introduced in the fluxing agent is mainly to better protect the wrapped red color, which is beneficial to the stability of the wrapped red color at high temperature and prevents bubbling. Meanwhile, the magnesia reinforced porcelain red underglaze colorant of the present application is also suitable for the surface glazing of low-temperature frit glaze mainly using boron trioxide as the fluxing agent.

[0045] The present application has the following advantages:

[0046] The magnesia reinforced porcelain red underglaze colorant of the present application is applied to the magnesia reinforced porcelain body, and the glaze surface has high gloss (no orange color, no pinholes, no bubbling), pure and full color (good color on the glaze surface). DETAILED DESCRIPTION

[0047] The present application is further illustrated below in combination with examples.

[0048] The concept, specific scheme and generated technical effects of the present application will be described clearly and completely in combination with the embodiments below, so as to fully understand the purposes, features and effects of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application. Each technical feature in the present application can be combined with each other as long as they are not contradictory.

[0049] The present application provides a preparation method of a red underglaze colorant for magnesia reinforced porcelain, comprising the following steps:

[0050] Preparation of the red underglaze colorant: first, the potassium feldspar and half of the methyl cellulose are weighed according to the formula and loaded into a ball mill, water is added, and the weight ratio of the potassium feldspar and half of the methyl cellulose to water is 100:150-170, ball milling is performed for 12-15h to less than 0.05% of 325 mesh screen residue, then calcined zinc oxide, zirconium silicate, red material, the other half of the methyl cellulose and water are added, the ratio of the material (calcined zinc oxide, zirconium silicate, red material, the other half of the methyl cellulose) to water is 100:150-170, and the ball milling is continued for 4-6h, then the material is discharged from the mill, sieved through a 150-180 mesh sieve and de-ironed, and finally the specific gravity is measured by a specific gravity bottle to be between 1.32-1.35g / ml, and the flow rate is measured by a flow rate cup to be between 38-48s / 100ml.

[0051] Specifically, the mass percentage of each component in the preparation step of the red underglaze colorant is: potassium feldspar 65-70%, calcined zinc oxide 4-5%, zirconium silicate 3-4%, methyl cellulose 0.9-1.2%, and red material 20-26%. Among them, the content of K2O in the chemical composition of the potassium feldspar is 10-12% by mass percentage. The red material is selected from red materials with good encapsulation performance, stable color development and high temperature resistance.

[0052] The red material is preferably a zirconium silicate encapsulated cadmium selenium red material.

[0053] Specifically, the preparation method of the zirconium silicate encapsulated cadmium selenium red material comprises the following steps:

[0054] The chromophore CdS+CdSe includes (20-30%) CdS and (70-80%) CdSe by weight percentage, and the chromophore CdS+CdSe: zirconium oxide: silicon dioxide: mineralizer (sodium fluoride): fluxing agent (lithium carbonate) = 100: (50-60): (20-25): (3-5): (1-2), water is added, the ratio of the material to water is 100: (50-80), the raw materials are wet ball milled to a particle size of D50 < 2 μm, so that the chromophore is uniformly dispersed and agglomeration is avoided. The finely ground raw materials are dried and then placed in a kiln for high-temperature solid-phase reaction, the calcination temperature is 1250-1350°C, the atmosphere is an oxidizing atmosphere, and the firing time is 12-15 h. Finally, the calcined raw materials are crushed, washed, dried, and then subjected to secondary ball milling to D90 < 5 μm, thereby obtaining the wrapped red pigment.

[0055] The red underglaze colorant of the present application is used for magnesia reinforced porcelain. After high-temperature firing, the colorant can generate a stable intermediate layer, and after glazing and low-temperature glazing, the glaze surface is smooth and the color is pure and bright without pinholes and orange color phenomenon. The introduction of high-potassium potassium feldspar in the colorant can make the red colorant well combined with the body, so that the wrapped red pigment is fully melted, and the bubbling phenomenon caused by excessive flux melting of the wrapped red pigment is avoided.

[0056] Further introduction of calcined zinc oxide makes the red underglaze colorant melt better and increases the firing range of the red underglaze colorant. However, the amount of calcined zinc oxide cannot be too much because the temperature decreasing effect of zinc oxide is significant at high temperature, and excessive introduction of calcined zinc oxide will make the red underglaze colorant not resistant to high temperature, causing bubbling phenomenon. In the present application, only 4-5% of calcined zinc oxide can be introduced. The content of zirconium silicate is controlled at 3-4%. Although the addition of zirconium silicate can protect the wrapped red pigment, excessive addition of zirconium silicate will make the red color not transparent and appear milky.

[0057] Further introduction of methyl cellulose is because the specific gravity of the colorant is low, the colorant is easy to precipitate, and the addition of methyl cellulose can play a suspending role to prevent the colorant from precipitating, and can also improve the adhesion and drying strength of the colorant, which is beneficial to the operation of production. However, too much methyl cellulose will cause the colorant to be too thick and affect the color spraying effect.

[0058] Preferably, the potassium feldspar has a chemical composition of SiO2: 60-70%, Al2O3: 15-20%, CaO: 0.2-0.5%, K2O: 10-12%, Na2O: 2-3%, and the balance is other components; the content of K2O cannot be too low.

[0059] An application method using the red underglaze colorant prepared above, comprising the following steps:

[0060] Preparation of blank: the surface-finished magnesium reinforced porcelain blank, the content of MgO in the magnesium reinforced porcelain blank used in the application reaching 22% or more, is put into a bisque firing kiln for low-temperature bisque firing, the bisque firing temperature is 960-980℃, the bisque firing time is 8-10 hours, and the bisque firing atmosphere is oxidation atmosphere.

[0061] Color spraying: the prepared red underglaze colorant is added into an air compressor gun, and the low-temperature bisque blank placed on a rotating disc is sprayed with color, in the process of color spraying, the rotating disc needs to be rotated, a uniform color spraying device is obtained, and the thickness of the colorant adhered to the surface of the low-temperature bisque blank is between 0.15-0.3mm.

[0062] Color baking: the color-sprayed device is placed into a high-temperature kiln for color baking, the color baking temperature is 1280±5℃, the baking time is 12-15 hours, and the baking atmosphere is oxidation atmosphere.

[0063] Polishing and cleaning: after the color-baked blank is polished and cleaned, a porcelainized color blank with smooth and clean surface is obtained, and then the blank is placed into a drying room for drying, the drying room temperature is 60-70℃, the drying time is 3-5 hours, and a dry device is formed for standby use.

[0064] Cooling device: the dried blank is taken out of the drying room and naturally cooled in room temperature air.

[0065] Glazing: the magnesium reinforced porcelain glaze used in the application is a low-temperature fused glaze taking boron trioxide as the main flux, the magnesium reinforced porcelain glaze is added into an air compressor gun, and the red color blank placed on a rotating disc is sprayed with glaze, in the process of glazing, the rotating disc needs to be rotated, the device is uniformly glazed, and the thickness of the glaze layer adhered to the red color blank needs to be between 0.2-0.4mm.

[0066] Air drying: the glazed device is placed in a special area and naturally air dried in room temperature air until the glazed blank is completely dried and then is put into a glaze firing kiln.

[0067] Glaze firing: the completely dried glazed device is put into a glaze firing kiln for glaze firing, the glaze firing temperature is 1110-1130℃, the glaze firing time is 10-12 hours, and the glaze firing atmosphere is oxidation atmosphere.

[0068] The magnesium reinforced porcelain red underglaze color product of the application fills the blank of magnesium reinforced porcelain production underglaze color, and all technical indexes can completely meet the demand of the domestic market, and the qualified rate of firing reaches 85% or more.

[0069] The potassium feldspar in the following examples and comparative examples has the chemical composition of SiO2: 67%, Al2O3: 17%, CaO: 0.22%, K2O: 11.2%, Na2O: 2.7%, and the balance is other components.

[0070] The red coated material is a zirconium silicate coated cadmium selenium red material, and the preparation method is as follows: the chromophore CdS+CdSe includes 20% CdS and 80% CdSe by weight percentage, the chromophore CdS+CdSe: zirconium oxide: silicon dioxide: mineralizer (sodium fluoride): fluxing agent (lithium carbonate) = 100:60:20:5:2, water is added, the ratio of the material to water is 100:50, the raw materials are wet ball milled to a particle size of D50<2 μm, so that the chromophore is uniformly dispersed and agglomeration is avoided. The finely ground raw materials are dried and then placed in a kiln for high temperature solid phase reaction, the calcination temperature is 1300°C, the atmosphere is an oxidizing atmosphere, and the firing time is 12 h. Finally, the calcined raw materials are crushed, washed, dried, and then subjected to secondary ball milling to D90<5 μm, thereby obtaining the coated red material.

[0071] The composition of the magnesia reinforced porcelain body is SiO2: 62.8%, Al2O3: 4.9%, CaO: 2.6%, MgO: 22.1%, K2O: 0.82%, Na2O: 0.3%, and the balance is other components. The raw materials of these components are weighed according to the ratio, added with a certain amount of water in a ball mill, the ratio of the material to water is 100:30, and the ball milling time is 15 h. After ball milling, it is sieved through a 250 mesh sieve and iron is removed, the ball milling fineness is less than 0.05% on a 325 mesh sieve. The obtained slurry is pressed into a mud cake by a filter press and aged. Finally, the mud cake is converted into slurry or mud strip according to production needs, placed in a gypsum mold to form a grouting mud blank or a rolling mud blank. The mud blank is then finished to obtain the required precision blank.

[0072] The composition of the low temperature frit glaze with boric oxide as the main flux is SiO2: 54.6%, Al2O3: 11.8%, CaO: 8.5%, MgO: 0.7%, K2O: 3.4%, Na2O: 2.4%, ZnO: 1.9%, Li2O: 1.9%, B2O3: 11.8%, and the balance is other components. The raw materials are weighed and mixed uniformly according to the ratio, then placed in a frit furnace for high temperature calcination at 1300-1350°C. The obtained glass melt is condensed into frits by water quenching method, then mixed with water and placed in a ball mill, the ratio of the material to water is 100:35, the ball milling time is 25 h, and the ball milling fineness is less than 0.05% on a 325 mesh sieve. After ball milling, it is sieved through a 250 mesh sieve and iron is removed, thereby obtaining the low temperature frit glaze for magnesia reinforced porcelain.

[0073] Examples A1-A6:

[0074] Preparation of red underglaze colorant: the specific addition is shown in Table 1. First, the potassium feldspar and half of the methyl cellulose are weighed according to the formula and put into a ball mill, water is added, the weight ratio of potassium feldspar and half of the methyl cellulose to water is 100:150, ball milling for 15h, the sieve residue is <0.05% to 325 mesh, then the calcined zinc oxide, zirconium silicate, red wrapped material, the other half of the methyl cellulose and water are added, the weight ratio of the material (calcined zinc oxide, zirconium silicate, red wrapped material, the other half of the methyl cellulose) to water is 100:150, continue to ball mill for 5h, take out the mill, pass through a 150 mesh sieve and remove iron, finally measure the specific gravity to 1.34g / ml by using a specific gravity bottle and the flow rate to 48s / 100ml by using a flow rate cup.

[0075] An application method using the above prepared red underglaze colorant, comprising the following steps:

[0076] Preparation of blank: the MgO content in the magnesia reinforced porcelain body used in the present application reaches more than 22%, the magnesia reinforced porcelain blank with the surface finished is put into a bisque kiln for low temperature bisque firing, the bisque firing temperature is 980℃, the firing time is 10 hours, and the bisque kiln atmosphere is oxidation atmosphere.

[0077] Color spraying: the prepared red underglaze colorant is added into an air pressure gun, and the low temperature bisque blank placed on a rotating disc is sprayed with color, in the process of color spraying, the rotating disc needs to be rotated, a uniform color spraying device is obtained, and the thickness of the colorant adhered to the surface of the low temperature bisque blank should be between 0.15-0.3mm.

[0078] Color baking: the color sprayed device is put into a high temperature kiln for color baking, the color baking temperature is 1280±5℃, the firing time is 15 hours, and the firing atmosphere is oxidation atmosphere.

[0079] Polishing and cleaning: after the high temperature color baked blank is polished and cleaned, a smooth and clean porcelainized color blank is obtained, and then the blank is put into a drying room for drying, the drying temperature is 60-70℃, the drying time is 3-5 hours, and a dry device is formed for standby use.

[0080] Cooling device: the dried blank is taken out of the drying room and placed in a special area to cool naturally under room temperature air.

[0081] Glazing: the magnesia reinforced porcelain glaze used in the present embodiment is a low temperature frit glaze taking boron trioxide as the main flux. The magnesia reinforced porcelain glaze is added into an air pressure gun, and the red porcelainized color blank placed on a rotating disc is sprayed with glaze, in the process of glazing, the rotating disc needs to be rotated, the glazing of the device is uniform, and the thickness of the glaze adhered to the red color blank needs to be between 0.2-0.4mm.

[0082] Air drying: the glazing device is placed in a special area to air dry naturally under room temperature air until the glazing blank is completely dry before being put into the kiln for glaze firing.

[0083] firing: the glazing device after complete drying is put into a firing kiln, the firing temperature is 1120℃, the firing time is 10 hours, and the firing atmosphere is oxidation atmosphere.

[0084] Table 1: ratio of red underglaze colorant of examples A1-A6

[0085]

[0086] Table 2: glaze surface results after firing of examples A1-A6

[0087] Item A1 A2 A3 A4 A5 A6 Glaze Orange Color None Little Severe None None None Glaze Pinhole None Yes Severe None None None High Temperature Baking Color Blister None Little Yes None None None Glaze Color Good Bad Bad Good Good Color Light

[0088] From the above table, A1 and A2, A3, the content of potassium feldspar in fluxing agent gradually decreases, and the colorant is increased, which has a special great influence on high temperature baking color effect and glaze. Because the fluxing agent is reduced, the colorant cannot be completely melted, and the free colorant is easy to generate colorant bubbles, thereby affecting the glaze quality. In examples A4 and A5, although the potassium feldspar is increased compared with A1, it has little effect on the glaze, which shows that the amount of potassium feldspar in this red underglaze colorant formula can be within this range. A6 adds too much potassium feldspar and reduces the amount of colorant, although the glaze gloss is not affected, but the color saturation is reduced, making the color light white. Therefore, it is known that the potassium feldspar in this scheme is between 65-70%, and the red material is wrapped between 20-26%, which has the best effect.

[0089] Examples B1-B5

[0090] Preparation of red underglaze colorant: the specific addition is shown in Table 3. First, the potassium feldspar and half of the methyl cellulose are weighed according to the formula and put into the ball mill, add water, the weight ratio of potassium feldspar and half of the methyl cellulose to water is 100:150, ball mill for 15h to 325 mesh sieve residue <0.05%, then add calcined zinc oxide, zirconium silicate, wrapped red material, the other half of the methyl cellulose and water, the ratio of material (calcined zinc oxide, zirconium silicate, wrapped red material, the other half of the methyl cellulose) to water is: 100:150, continue to ball mill for 5h, discharge, pass through 150 mesh sieve and remove iron, finally adjust the specific gravity to 1.34g / ml, and the flow rate is 48s / 100ml.

[0091] An application method using the prepared red underglaze colorant, comprising the following steps:

[0092] The same as examples A1-A6.

[0093] Table 3: ratio of red underglaze colorant of examples B1-B5

[0094]

[0095] Table 4: Glaze results after firing of examples B1-B5

[0096] Item B1 B2 B3 B4 B5 Glaze Orange Color Yes None None None Little Glaze Pinhole Yes Little None None Yes High Temperature Baking Color Blister None None None None Little Color Good Good Good Good Bad

[0097] From the above table, it can be seen that B1 and B2, B3 are gradually reduced potassium feldspar, and calcined zinc oxide is increased, and the amount of colorant is unchanged, which has a direct impact on the glaze. Because the fluxing effect of zinc at high temperature is stronger than that of potassium feldspar, adding a small amount of zinc to replace potassium feldspar can make the red colorant melt better, and there will be no gas emission during firing, reducing the probability of pinholes on the glaze. Example B4, the glaze after firing is good, and the baking color also does not appear the phenomenon of blistering. While example B5, due to the addition of too much zinc, the red colorant reduces the fire resistance, causing the colorant to overheat during baking, resulting in blistering and affecting the quality of the glaze. Therefore, it can be seen that calcined zinc oxide has a strong fluxing effect at high temperatures, so its introduction in the formula has a small range. In this scheme, the amount of calcined zinc oxide is between 4-5%, which has the best effect.

[0098] Example C

[0099] Preparation of red glaze under colorant: the specific addition is shown in Table 5. First, weigh the potassium feldspar and half of the methyl cellulose according to the formula and put it into the ball mill, add water, the weight ratio of potassium feldspar and half of the methyl cellulose to water is: 100-150, ball mill for 15h to 325 mesh screen residue <0.05%, then add calcined zinc oxide, zirconium silicate, red coated material, the other half of the methyl cellulose and water, the ratio of material (calcined zinc oxide, zirconium silicate, red coated material, the other half of the methyl cellulose) to water is 100:150, continue to ball mill for 5h, take out the mill, pass through a 150 mesh screen and remove iron, finally adjust the specific gravity to 1.34g / ml, and the flow rate is 48s / 100ml.

[0100] An application method using the above prepared red glaze under colorant, comprising the following steps:

[0101] The same as examples A1-A6.

[0102] Table 5: Ratio of red glaze under colorant of examples C1-C6

[0103]

[0104] Table 6: Glaze results after firing of examples C1-C6

[0105] Item C1 C2 C3 C4 C5 C6 Glaze Orange Color Yes Little None None None None Glaze Pinhole Yes Little None None None None High Temperature Baking Color Blister Yes Little None None None None Glaze Color Bad Bad Good Good Good Color Obvious Opacity

[0106] As can be seen from the table above, when comparing C1 with C2, C3, C4, and C5, all other raw materials are within the formulation range. Gradually increasing the amount of zirconium silicate improves the high-temperature baking performance and glaze quality, indicating that zirconium silicate provides further protection for the encapsulated red material, making it more heat-resistant and stable. In contrast, in Example C6, zirconium silicate is added beyond the formulation range. While the glaze does not develop orange tint or pinhole defects, it does affect the color development of the red, making it opaque and milky. This demonstrates that zirconium silicate helps stabilize the encapsulated red during high-temperature baking. However, zirconium silicate has a strong opacifying property, so in this solution, a zirconium silicate dosage of 3-4% achieves the best results.

[0107] Example D

[0108] Preparation of red underglaze colorant: its composition by mass percentage is: potassium feldspar 68%, calcined zinc oxide 4.5%, zirconium silicate 3.5%, methyl cellulose 1%, and wrapped red material 23%, among which the chemical composition of potassium feldspar is: SiO2: 67%, Al2O3: 17%, CaO: 0.22%, K2O: 11.2%, Na2O: 2.7%, and the balance is other ingredients.

[0109] Comparative Example D1

[0110] Preparation of red underglaze colorant: its composition by mass percentage is: 68% ordinary potassium feldspar, 4.5% calcined zinc oxide, 3.5% zirconium silicate, 1% methyl cellulose, and 23% wrapped red material, among which the chemical composition of ordinary potassium feldspar is: SiO2: 74%, Al2O3: 14%, CaO: 0.56%, K2O: 8.64%, Na2O: 2.6%, and the balance is other ingredients.

[0111] Comparative Example D2

[0112] Preparation of red underglaze colorant: its composition by mass percentage is: potassium feldspar 68%, uncalcined zinc oxide 4.5%, zirconium silicate 3.5%, methyl cellulose 1%, and wrapped red material 23%, among which the chemical composition of potassium feldspar is: SiO2: 67%, Al2O3: 17%, CaO: 0.22%, K2O: 11.2%, Na2O: 2.7%, and the balance is other ingredients.

[0113] Comparative Example D3

[0114] Preparation of red underglaze colorant: its composition by mass percentage is: potassium feldspar 68%, calcined zinc oxide 4.5%, zirconium oxide 3.5%, methyl cellulose 1%, and wrapped red material 23%, among which the chemical composition of potassium feldspar is: SiO2: 67%, Al2O3: 17%, CaO: 0.22%, K2O: 11.2%, Na2O: 2.7%, and the balance is other ingredients.

[0115] Comparative Example D4

[0116] Preparation of water blue underglaze colorant: its composition is as follows in terms of mass percentage: potassium feldspar 68%, calcined zinc oxide 4.5%, zirconium silicate 3.5%, methyl cellulose 1%, vanadium zirconium blue pigment 23%, wherein the chemical composition of potassium feldspar is: SiO2: 67%, Al2O3: 17%, CaO: 0.22%, K2O: 11.2%, Na2O: 2.7%, and the balance is other components. Vanadium zirconium blue pigment is a colorant with stable color development and high temperature resistance, which is a commonly commercially available colorant, and the colorant name is 26222, and the main components include vanadium pentoxide, quartz, zirconium dioxide, etc.

[0117] Comparative Example D5

[0118] Preparation of red underglaze colorant: its composition is as follows in terms of mass percentage: potassium feldspar 68%, calcined zinc oxide 4.5%, zirconium silicate 3.5%, methyl cellulose 1%, and uncoated red pigment 23%, wherein the chemical composition of potassium feldspar is: SiO2: 67%, Al2O3: 17%, CaO: 0.22%, K2O: 11.2%, Na2O: 2.7%, and the balance is other components. Uncoated red pigment is a red pigment without zirconium silicate coating, and its main component is CdS+CdSe (including 70% CdS and 30% CdSe in terms of weight percentage), and it is not calcined by further adding zirconium oxide and silicon dioxide, so that the CdS+CdSe red pigment loses the protection of zirconium oxide and silicon dioxide and is easy to volatilize during high-temperature firing, making the pigment not resistant to high temperature.

[0119] The specific preparation method of the underglaze colorant of the above-mentioned examples D and comparative examples D1-D5 is as follows:

[0120] First, the potassium feldspar and half of the methyl cellulose are weighed according to the formula and loaded into a ball mill, water is added, and the weight ratio of potassium feldspar and half of the methyl cellulose to water is 100:150, ball milling for 15h to less than 0.05% on a 325 mesh sieve, then calcined zinc oxide or uncalcined zinc oxide, zirconium silicate or zirconium oxide, coated red pigment or uncoated red pigment or vanadium zirconium blue pigment, the other half of the methyl cellulose and water are added, and the ratio of the material (calcined zinc oxide or uncalcined zinc oxide, zirconium silicate or zirconium oxide, coated red pigment or uncoated red pigment or vanadium zirconium blue pigment, the other half of the methyl cellulose) to water is 100:150, and the ball milling is continued for 5h, then the material is discharged from the mill, sieved through a 150 mesh sieve and de-ironed, and finally the specific gravity is adjusted to 1.34g / ml and the flow rate is 48s / 100ml.

[0121] An application method using the above-prepared underglaze colorant, comprising the following steps:

[0122] The same as examples A1-A6.

[0123] The glaze effects of Example D and Comparative Examples D1-D5 were compared, as shown in Table 7:

[0124] Table 7: Comparison of Example D and Comparative Examples D1-D5

[0125]

[0126] As shown by the comparison of Comparative Example D1 and Example D, the ordinary potassium feldspar used in Comparative Example D1 has an internal potassium oxide content of only 8.6%, and the silica content is increased, so the ordinary potassium feldspar has poor fluxing effect. When the same amount is added, the refractoriness of the fluxing agent is increased, the internal wrapped red pigment cannot be well melted, and excess pigment is precipitated, resulting in pigment bubbles, thereby affecting the glaze quality.

[0127] As shown by the comparison of Comparative Example D2 and Example D, the uncalcined zinc oxide used in Comparative Example D2 has more volatile substances, unstable crystal structure, and high chemical reactivity, which causes the formula to be unstable, thereby affecting the glaze quality.

[0128] As shown by the comparison of Comparative Example D3 and Example D, the zirconia used in Comparative Example D3 has silica and zirconia, and when added to the fluxing agent, the silica can be melted with other substances to form a stable crystal phase, while the zirconia only contains zirconia components, and has strong opalescent effect and relatively small amount, and cannot play a stabilizing and protective role on the wrapped red pigment. Therefore, the addition of zirconia will affect the glaze quality.

[0129] As shown by the comparison of Comparative Example D4 and Example D, the wrapped red pigment in Comparative Example D4 is replaced by the same proportion of vanadium zirconium green pigment, although the vanadium zirconium green pigment is stable and resistant to high temperature at high temperature, but the color development is not good under this fluxing agent. Because the vanadium zirconium green pigment and the wrapped red pigment have completely different manufacturing processes and chemical compositions.

[0130] As shown by the comparison of Comparative Example D5 and Example D, the un-wrapped red pigment is used in Comparative Example D5, and because the un-wrapped red pigment does not have the protection of the zirconium silicate layer, the red pigment is not resistant to high temperature at high temperature, which will cause the color to bubble, and also cause discoloration and instability at high temperature.

[0131] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the described embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present application. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. A red underglaze colorant for magnesium-reinforced porcelain, characterized in that: The solid content includes the following components by weight: Potash feldspar 65-70%, calcined zinc oxide 4-5%, zirconium silicate 3-4%, methyl cellulose 0.9-1.2%, wrapped red material 20-26%; The weight content of K2O in potassium feldspar is 10-12%.

2. The red underglaze colorant for magnesium-reinforced porcelain according to claim 1, characterized in that: The wrapped red material is a zirconium silicate wrapped cadmium selenium red material; The chemical composition of the potassium feldspar is SiO2: 60-70%, Al2O3: 15-20%, CaO: 0.2-0.5%, K2O: 10-12%, Na2O: 2-3%, and the balance is other components.

3. The red underglaze colorant for magnesia-reinforced porcelain according to claim 1, characterized in that: The magnesia-reinforced porcelain red underglaze colorant also includes water, and the weight ratio of the solid component to the water is 100:150-170; The specific gravity of the magnesia-reinforced porcelain red underglaze colorant is 1.32-1.35 g / ml, and the flow rate is 38-48 s / 100 ml.

4. The method for preparing the red underglaze colorant for magnesium-reinforced porcelain according to any one of claims 1 to 3, characterized in that: The steps include: S1: Potassium feldspar and half of methyl cellulose were ball-milled with water; S2: Calcined zinc oxide, zirconium silicate, red coating material, the remaining half of methyl cellulose and water are added, and ball milling is continued. After the mixture is removed from the mill, the mixture is sieved and iron is removed to obtain a magnesia-reinforced porcelain red underglaze colorant.

5. The preparation method according to claim 4, characterized in that In step S1, the potassium feldspar and half of the methyl cellulose are ball-milled with water, and the weight ratio of the potassium feldspar and half of the methyl cellulose to water is 100:150-170; In step S1, the potassium feldspar and half of the methyl cellulose are ball-milled with water for 12-15 hours; In step S1, the potassium feldspar and half of the methyl cellulose are ball-milled with water until the residue on a 325-mesh sieve is less than 0.05%; In step S2, the mass ratio of the total mass of calcined zinc oxide, zirconium silicate, coated red material and the other half of methyl cellulose to water is 100:150-170; In step S2, the ball milling is continued for 4-6 hours; In step S2, the sieving is performed through a 150-180 mesh sieve.

6. A red underglaze color of magnesium-reinforced porcelain, characterized in that: It comprises a magnesia-reinforced porcelain body, a red underglaze color layer and a protective glaze layer; the red underglaze color layer is prepared from the magnesia-reinforced porcelain red underglaze colorant according to any one of claims 1 to 3 or the magnesia-reinforced porcelain red underglaze colorant prepared by the preparation method according to any one of claims 4 to 5.

7. The red underglaze color of magnesia-reinforced porcelain according to claim 6, characterized in that: The weight content of MgO in the magnesium-reinforced porcelain body is above 22%; The protective glaze layer is prepared from a low-temperature frit glaze with boron trioxide as a main flux.

8. The red underglaze color of magnesia-reinforced porcelain according to claim 7, characterized in that: The composition of the magnesia-reinforced porcelain body is SiO2: 61-63%, Al2O3: 4-5%, CaO: 2-3%, MgO: 22-24%, K2O: 0.5-1%, Na2O: 0.2-0.5%, and the balance is other ingredients; The components of the low-temperature frit glaze are SiO2: 53-55%, Al2O3: 10-12%, CaO: 8-9%, MgO: 0.5-1%, K2O: 3-4%, Na2O: 2-3%, ZnO: 1.5-2%, Li2O: 1.5-2%, B2O3: 10-12%, and the balance is other ingredients.

9. The method for preparing red underglaze color of magnesia-reinforced porcelain according to any one of claims 6 to 8, characterized in that: The steps include: (1) bisque firing the magnesium-reinforced porcelain body at low temperature; (2) spraying a red underglaze colorant of magnesium-reinforced porcelain on a magnesium-reinforced porcelain body after low-temperature bisque firing, and then performing high-temperature baking, polishing, cleaning, drying, and cooling to obtain a magnesium-reinforced porcelain red color body; (3) glazing the red color body of the magnesium-enhanced porcelain, drying it in the shade, and glaze firing it to obtain the magnesium-enhanced porcelain red underglaze color product.

10. The preparation method according to claim 9, characterized in that The low-temperature biscuit calcination in step (1) is carried out at a temperature of 960-980° C. for 8-10 hours in an oxidizing atmosphere; Step (2) during the spraying process, the low-temperature bisque-fired magnesium-reinforced porcelain body is rotated while spraying; The thickness of the spray paint in step (2) is 0.15-0.3 mm; The high temperature baking temperature of step (2) is 1280±5°C, the time is 12-15 hours, and the atmosphere is an oxidizing atmosphere; The drying time in step (2) is 3-5 hours; The cooling in step (2) is to cool naturally under room temperature air; Step (3) during the glazing process, the magnesium-reinforced porcelain red color blank is rotated while glazing; The thickness of the glazing in step (3) is 0.2-0.4 mm; The drying in the shade in step (3) is natural drying in the shade under room temperature air; The glaze firing temperature in step (3) is 1110-1130° C., the firing time is 10-12 hours, and the atmosphere is an oxidizing atmosphere.

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