A whitening base for ceramic tiles and its application method

Abstract

This invention relates to the field of ceramic tile base slurry preparation technology, and discloses a ceramic tile whitening base slurry and its application method. The ceramic tile whitening base slurry, by mass percentage, comprises 59.5%–66.5% talc powder, 25.5%–28.5% magnesium oxide powder, 0.3%–0.8% suspending agent, and 0.1%–0.3% dispersant, with the balance being water. The application method includes a spraying step, whereby the ceramic tile whitening base slurry is sprayed onto the bottom surface of the ceramic tile body to be fired using a base slurry spraying device. In addition to fulfilling the isolation and anti-sticking function of conventional ceramic tile base slurries, the ceramic tile whitening base slurry lowers the melting temperature of the base slurry, forming an integrated sintered layer with the ceramic tile body. Furthermore, it can react with the alumina in the ceramic tile body to generate magnesium aluminum spinel, which has high crystal hardness and a low coefficient of thermal expansion, significantly improving the whiteness and thermal stability of the tile base. By spraying the base slurry onto the surface of the ceramic tile and then firing it for vitrification, the whiteness of the tile base can be increased by 10° or more without changing the ceramic tile formula, achieving a high-whiteness effect throughout the ceramic tile at low cost.

Description

Technical Field

[0001] This invention relates to the field of ceramic tile base slurry preparation technology, and in particular to a ceramic tile whitening base slurry and its application method. Background Technology

[0002] In the ceramic tile production process, to prevent the tile blanks from softening at high temperatures during firing and adhering to the conveyor rollers (i.e., "sticking"), the industry commonly employs a pretreatment process of applying a layer of high-temperature slurry to the bottom of the tile blank before it enters the kiln. The alumina (Al2O3) or magnesium oxide (MgO) added to the slurry of commercially available ceramic tiles has a high whiteness (Al2O3 has a whiteness of approximately 90°–95°, and MgO has an even higher whiteness), theoretically giving the tile a light white appearance on the back. However, in practical applications, the whitening effect is very limited for the following reasons: the melting point of alumina is approximately 2050℃, and that of magnesium oxide is approximately 2800℃, while the firing temperature of ceramic tiles is 1000℃–1250℃, far lower than the melting points of alumina and magnesium oxide. This means that during the firing process, the slurry material cannot fully melt, diffuse, and chemically bond with the surface of the tile blank. The slurry layer is merely mechanically "attached" to the body; it does not melt or undergo redox reactions with the color-producing ions (Fe2O3, TiO2, etc.) in the body, nor does it form high-whiteness crystalline phases (such as the absence of magnesium aluminum spinel within the body). Therefore, it cannot "cover" the base color like adding whitening agents inside the body. Furthermore, because the slurry layer fails to form an integrated sintered layer with the body, the density and continuity of the slurry isolation are poor. Under repeated high temperatures and roller pressure, the slurry layer is prone to localized cracking, peeling, or even being "scraped away" by the rollers, resulting in partial exposure of the body and preventing the formation of a stable whitening layer on the brick's base. Therefore, existing ultra-white bricks require the addition of large amounts of high-cost whitening agents to the body and glaze formulations to achieve a uniformly ultra-white effect. Summary of the Invention

[0003] To address the aforementioned shortcomings, the present invention aims to provide a ceramic tile whitening base slurry and its application method. By lowering the melting temperature of the base slurry, the base slurry layer forms an integrated sintered layer with the ceramic tile body. Furthermore, it can react with the alumina in the ceramic tile body to generate magnesium aluminum spinel, which has high crystal hardness and low coefficient of thermal expansion, thus significantly improving the whiteness and thermal stability of the tile base.

[0004] To achieve this objective, the present invention adopts the following technical solution: A ceramic tile whitening base coat, by mass percentage, comprises 59.5%–66.5% talc powder, 25.5%–28.5% magnesium oxide powder, 0.3%–0.8% suspending agent, and 0.1%–0.3% dispersant, with the balance being water; The mass ratio of the talc powder to the magnesium oxide powder is 7:3.

[0005] Optionally, the slurry parameters of the ceramic tile whitening primer include a specific gravity of 2.5 g / cm³. 3 ~2.9 g / cm 3 The particle size is D50 = 5μm to 15μm, and the flow rate is 25 seconds to 40 seconds for the Tu-4 cup.

[0006] Furthermore, the application method of the ceramic tile whitening primer includes: The preparation steps involve mixing the raw materials according to a predetermined ratio to obtain a mixture, and then ball milling the mixture until the preset slurry parameters are achieved to obtain the ceramic tile whitening base slurry. In the slurry supply step, the prepared ceramic tile whitening base slurry is transported to a slurry tank, and water is added to the slurry tank to mix until the specific gravity of the ceramic tile whitening base slurry is 1.05 g / cm³. 3 ~1.15 g / cm 3 ; In the spraying step, a base slurry spraying device is used to spray the tile whitening base slurry from the slurry supply step onto the bottom surface of the tile body to be fired. The base slurry spraying device includes a conveying roller table and a spraying mechanism. The spraying mechanism is located below the conveying roller table and has multiple nozzles. The nozzles of the nozzles face upwards, and the multiple nozzles are spaced apart and staggered to form a cross-shaped grid distribution. The conveying roller table transports the tile body to be fired, and the slurry tank pumps the tile whitening base slurry to the spraying mechanism. The nozzles are atomizing nozzles, and the nozzles spray the tile whitening base slurry onto the bottom surface of the tile body that they pass over. The working pressure of the nozzles is 30 bar.

[0007] Specifically, the spraying device also includes a scraping mechanism and a recovery mechanism, with the recovery mechanism installed below the spraying mechanism; The scraping mechanism includes an auxiliary conveyor belt, a frame, a scraper strip, a slurry collection hopper, and a flow guide pipe. The auxiliary conveyor belt is mounted above the conveying surface of the conveying roller table via the frame. The bottom section of the auxiliary conveyor belt and the conveying surface of the conveying roller table are vertically opposite each other to form a brick-moving space. The conveying direction of the bottom section of the auxiliary conveyor belt is the same as the conveying direction of the conveying roller table. The scraper strip is located above the auxiliary conveyor belt. Both ends of the scraper strip are connected to the frame. The bottom of the scraper strip abuts against the top section of the auxiliary conveyor belt. Slurry flow gaps are left between the two sides of the auxiliary conveyor belt and the frame. The scraper is inclined to the left and right, with one end of the scraper close to the front end of the auxiliary conveyor belt and the other end close to the rear end of the auxiliary conveyor belt. The slurry collection hopper is installed on the frame and located below one end of the scraper, with the top opening of the slurry collection hopper located at the corresponding slurry flow gap. The bottom of the slurry collection hopper is connected to one end of the diversion conduit, and the other end of the diversion conduit passes through the conveyor roller table and the spraying mechanism and then connects to the recycling mechanism.

[0008] Preferably, the conveying roller table is provided with multiple roller bars, each roller bar including a roller bar body and a spiral body. The spiral body is spirally wound around the peripheral wall of the roller bar body, and the thickness of the spiral body gradually decreases radially outward from the peripheral wall of the roller bar body to form a tip.

[0009] Furthermore, the shotcrete mechanism also includes a nozzle mounting bracket and multiple slide rails. The multiple slide rails are mounted on the base of the conveying roller table, the roller is rotatably mounted on the top of the base, the multiple slide rails are located below the roller, and the multiple slide rails and the roller are parallel to each other. The nozzle mounting bracket includes a connecting plate and multiple slide bars. The multiple slide bars correspond one-to-one with the multiple slide rails and are slidably connected. One end of the multiple slide bars is connected to the inner side of the connecting plate. The slide bars have mounting slots along their length. The nozzle is mounted in the mounting slots of the slide bars by fasteners. The nozzles on any two adjacent sliders are staggered.

[0010] Specifically, the slurry supply step uses a slurry supply mechanism, which includes a slurry tank, a high-pressure pump, a main slurry supply pipe, and multiple slurry supply branch pipes. The outlet end of the slurry tank is connected to the input end of the high-pressure pump, and the output end of the high-pressure pump is connected to the input end of the main slurry supply pipe. The multiple output ends of the main slurry supply pipe are connected to the input ends of the multiple slurry supply branch pipes in a one-to-one correspondence. Each slide bar is equipped with one slurry supply branch pipe, and the nozzles on the same slide bar are connected in series to the same slurry supply branch pipe. Each slurry supply branch pipe is equipped with a pressure reducing valve at its output end.

[0011] Furthermore, in the shotcrete step, the recycling mechanism includes a recycling hopper and a recycling output pipe, wherein the recycling hopper is installed on the base and located below the multiple slide rails; The connecting plate of the nozzle mounting bracket is located below the slurry hopper. The bottom of the slurry hopper is connected to one end of the drainage conduit. The other end of the drainage conduit passes through the gap between the rollers and the gap between the slide rails in sequence and then connects to the recovery hopper. The base is surrounded by sealing plates, and the base has a maintenance port. The nozzle mounting bracket is located in the maintenance port, and the connecting plate can be moved to close the maintenance port. The recovery output pipe is connected to the bottom of the recovery hopper, and the recovery output pipe is located below the maintenance port.

[0012] The technical solution provided by this invention may include the following beneficial effects: In addition to fulfilling the isolation and anti-sticking functions of conventional tile base coats, the described tile whitening primer also lowers the melting temperature of the primer, forming an integrated sintered layer with the tile body. Furthermore, it reacts with the alumina in the tile body to generate magnesium aluminum spinel, which has high crystal hardness and a low coefficient of thermal expansion, significantly improving the whiteness and thermal stability of the tile base. By spraying this primer onto the surface of the tile body before firing and vitrification, a whiteness increase of 10° or more can be achieved without altering the tile body formula, enabling a low-cost, ultra-white effect throughout the tile. Thus, by spraying the described tile whitening primer onto the bottom surface of the tile body to be fired, both the isolation and anti-sticking functions and the whitening effect on the tile base are achieved. Attached Figure Description

[0013] Figure 1 This is an overall structural diagram of the spraying slurry device according to one embodiment of the present invention.

[0014] Figure 2 This is a cross-sectional view of the spraying slurry device according to one embodiment of the present invention.

[0015] Figure 3 This is a structural diagram of the scraping mechanism according to one embodiment of the present invention.

[0016] Figure 4 This is a top view of a tile spraying base coat device according to one embodiment of the present invention.

[0017] Figure 5 This is one embodiment of the present invention. Figure 4 Enlarged view at point A.

[0018] Figure 6 This is a structural diagram of the slurry supply mechanism according to one embodiment of the present invention.

[0019] Figure 7 This is a structural diagram of a roller bar according to one embodiment of the present invention.

[0020] Figure 8 This is a comparison chart of ceramic tile firing curves according to one embodiment of the present invention.

[0021] Figure 9 This is a picture of the bottom of the tile in Embodiment 3 of the present invention.

[0022] Figure 10 This is a picture of the bottom of the tile in Comparative Example 2 of the present invention.

[0023] The components include: conveyor roller table 1; spraying mechanism 2; scraping mechanism 3; recovery mechanism 4; auxiliary conveyor belt 31; frame 32; scraping strip 33; nozzle 21; slurry collection hopper 34; diversion conduit 35; roller bar 11; roller bar body 111; spiral body 112; nozzle mounting bracket 22; slide rail 23; connecting plate 220; slide bar 221; mounting strip hole 222; slurry supply mechanism 5; slurry tank 51; high pressure pump 52; main slurry supply pipe 53; branch slurry supply pipe 54; pressure reducing valve 55; recovery hopper 41; base 12; sealing plate 121; maintenance port 122; recovery output pipe 42; first drive motor 13; second drive motor 36. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the system or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, features defined with "first" and "second" may explicitly or implicitly include one or more of these features, used to distinguish and describe features, without any order or emphasis.

[0026] In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0028] The following is combined with Figures 1 to 8 This invention describes the ceramic tile whitening base mortar and its application method.

[0029] The ceramic tile whitening base mortar of the present invention comprises, by mass percentage, 59.5%–66.5% talc powder, 25.5%–28.5% magnesium oxide powder, 0.3%–0.8% suspending agent, and 0.1%–0.3% dispersant, with the balance being water; The mass ratio of the talc powder to the magnesium oxide powder is 7:3.

[0030] The ceramic tile whitening base slurry mainly comprises talc powder and magnesium oxide powder. When mixed in a 7:3 ratio, they not only blend well but also synergistically whiten, optimize firing, and improve thermal stability. Talc powder (mainly composed of 3MgO•4SiO2•H2O) decomposes at high temperatures to generate active magnesium oxide (MgO) and metasilicates; therefore, talc powder essentially acts as a "slow-release carrier" for magnesium oxide. In actual production, using both in combination can balance process stability and whiteness improvement. The synergistic whitening effect is achieved because the magnesium oxide produced by the high-temperature decomposition of talc powder has a strong whitening effect, promoting emulsification of the tile surface, enhancing light scattering, and making the tiles appear whiter and brighter. The combined use of talc powder and magnesium oxide powder achieves "double whitening," especially suitable for the body and glaze formulations of high-end white porcelain and ultra-white tiles. Optimized firing is achieved because magnesium oxide, acting as a flux, forms a low-melting-point eutectic with SiO2 and Al2O3 in the body at high temperatures, reducing the sintering temperature by 50–100℃. Figure 8 As shown, the upper red curve represents the firing curve of the tile without the aforementioned whitening base slurry, while the lower purple curve represents the firing curve of the tile with the aforementioned whitening base slurry. The maximum temperature difference between the two is nearly 100℃. Talc powder gradually decomposes in the 800–1200℃ range, resulting in a more uniform release of MgO, avoiding excessively high local concentrations that could lead to blistering or abnormal crystallization on the glaze surface, thus improving firing stability. Regarding thermal stability: MgO can react with Al2O3 in the body to form magnesium aluminum spinel (MgAl2O4). This crystalline phase has high hardness and a low coefficient of thermal expansion, and can "pin" grain boundaries, improving the tile's flexural strength and thermal shock resistance.

[0031] It should be noted that the talc powder ratio should be between 60.5% and 66.5%. If it exceeds this range, the low temperature will affect the deformation and whiteness of the brick body. If it is below this range, the whitening effect of magnesium oxide will also be affected. The magnesium oxide powder ratio should be between 25.5% and 28.5%. If it exceeds this range, due to the high surface tension of MgO, it will react directly with SiO2 in the body during the heating process of 800-1200℃ to form forsterite (2MgO•SiO2), or with Al2O3 and SiO2 in the body to form cordierite. This process is characterized by concentrated heat release and a sharp increase in local liquid phase, resulting in defects such as bubbling and shrinkage. If it is below this range, the whitening effect will also be affected.

[0032] In summary, the aforementioned tile whitening base slurry, in addition to fulfilling the isolation and anti-sticking function of conventional tile base slurries, also lowers the melting temperature of the base slurry, forming an integrated sintered layer with the tile body. Furthermore, it reacts with the alumina in the tile body to generate magnesium aluminum spinel, which has high crystal hardness and a low coefficient of thermal expansion, significantly improving the whiteness and thermal stability of the tile base. By spraying it onto the surface of the tile body and then firing it for vitrification, a whiteness increase of 10° or more can be achieved without changing the tile body formula, enabling a low-cost, ultra-white effect throughout the tile. For example, tile body whiteness is divided into four categories: whitened tile (20°–30°), ordinary white tile (30°–40°), and ultra-white tile (over 45°). Applying the aforementioned tile whitening base slurry can make a whitened tile reach the whiteness of an ordinary white tile, or an ordinary white tile reach the whiteness of an ultra-white tile.

[0033] Specifically, the slurry parameters of the tile whitening base paste include a specific gravity of 2.5 g / cm³. 3 ~2.9 g / cm 3 The particle size is D50 = 5μm~15μm, and the flowability is 25 seconds~40 seconds for the Forte-4 cup. The specific gravity of the ceramic tile whitening primer is 2.5 g / cm³. 3 ~2.9 g / cm 3 This ensures high solids content and sufficient dry film thickness to isolate the rollers. The particle size of the tile whitening primer is D50=5μm~15μm. The slurry has good fluidity, forming a delicate surface of the primer layer. After sintering, the primer layer is dense and has few pores. The fluidity of the tile whitening primer is 25 seconds to 40 seconds from the Forecast-4 cup. The fluidity is suitable for roller or spray application. Excess slurry is easy to scrape off during construction, and the scraped slurry can flow smoothly into the slurry collection tank for recycling. It is neither too thin nor too sticky, and the thickness of the slurry adhering to the tile base is uniform and appropriate.

[0034] The above parameters are all measured using existing conventional or national standard methods. Specific gravity typically refers to the true density or density of the slurry (including the liquid phase) at 20°C, measured using a specific gravity cup or densitometer. Particle size refers to the cumulative 50% of particles (median diameter D50) as determined by laser particle size analysis. Flowability is specified according to national standard GB / T 1723 for coatings. 4. Viscosity cup (Φ4 mm, 100 mL), time required for slurry to completely drain from the bottom hole of the cup at room temperature (23±1℃).

[0035] Furthermore, the application method of the aforementioned ceramic tile whitening primer includes: The preparation steps involve mixing the raw materials according to a predetermined ratio to obtain a mixture, and then ball milling the mixture until the preset slurry parameters are achieved to obtain the ceramic tile whitening base slurry. In the slurry supply step, the prepared ceramic tile whitening base slurry is conveyed to the slurry tank 51, and water is added to the slurry tank 51 to mix until the specific gravity of the ceramic tile whitening base slurry is 1.05 g / cm³.3 ~1.15 g / cm 3 ; In the spraying step, the tile whitening base slurry from the supply step is sprayed onto the bottom surface of the tile body to be fired using a base slurry spraying device. Figure 1 As shown, the base slurry spraying device includes a conveying roller table 1 and a spraying mechanism 2. The spraying mechanism 2 is located below the conveying roller table 1 and is equipped with multiple nozzles 21. The nozzles of the nozzles 21 face upwards, and the multiple nozzles 21 are spaced apart and staggered to form a cross-shaped grid distribution. The conveying roller table 1 conveys the ceramic tile blank to be fired. The slurry tank 51 pumps the ceramic tile whitening base slurry to the spraying mechanism 2. The nozzles 21 are atomizing nozzles, which spray the ceramic tile whitening base slurry onto the bottom surface of the ceramic tile blank. The working pressure of the nozzles 21 is 30 bar.

[0036] The whitening base slurry is applied to the bottom surface of the ceramic tile body to be fired, thereby achieving both isolation and anti-sticking properties and a whitening effect on the tile base. The preparation steps are as follows: Raw materials are weighed according to the following mass percentages: 60.5%–66.5% talc powder, 25.5%–28.5% magnesium oxide powder, 5%–10% water, 0.3%–0.8% suspending agent, and 0.1%–0.3% dispersant; wherein the mass ratio of talc powder to magnesium oxide powder is 7:3, and the mixture is then ball-milled to achieve the preset slurry parameters: specific gravity of 2.5 g / cm³. 3 ~2.9 g / cm 3 The ceramic tile whitening base slurry is prepared by using a particle size of D50 of 5μm to 15μm and a flowability of 25 to 40 seconds for outflow from a Forte 4 cup. In the slurry supply step, water is added until the specific gravity of the ceramic tile whitening base slurry is 1.05 g / cm³. 3 ~1.15 g / cm 3 This is more conducive to spraying. In the spraying step, the base coat spraying device uses multiple nozzles 21 arranged in a cross-shaped grid to atomize and spray the whitening base coat of the ceramic tile, which greatly reduces the generation of spraying dead corners and spraying overlap areas, and the spraying thickness is more uniform.

[0037] Optionally, such as Figure 2 As shown, the spraying device also includes a scraping mechanism 3 and a recovery mechanism 4, with the recovery mechanism 4 installed below the spraying mechanism 2; The scraping mechanism 3 includes an auxiliary conveyor belt 31, a frame 32, scraper blades 33, a slurry collection hopper 34, and a drainage conduit 35, such as Figure 3 and Figure 4As shown, the auxiliary conveyor belt 31 is mounted above the conveying surface of the conveyor roller table 1 via the frame 32. The bottom belt section of the auxiliary conveyor belt 31 and the conveying surface of the conveyor roller table 1 are vertically opposite to each other and form a brick-moving space. The conveying direction of the bottom belt section of the auxiliary conveyor belt 31 is the same as the conveying direction of the conveyor roller table 1. The scraper strip 33 is located above the auxiliary conveyor belt 31. Both ends of the scraper strip 33 are connected to the frame 32. The bottom of the scraper strip 33 abuts against the top belt section of the auxiliary conveyor belt 31. A slurry flow gap is left between the two sides of the auxiliary conveyor belt 31 and the frame 32. The scraper bar 33 is inclined to the left and right. One end of the scraper bar 33 is close to the front end of the auxiliary conveyor belt 31, and the other end of the scraper bar 33 is close to the rear end of the auxiliary conveyor belt 31. The slurry collection hopper 34 is installed on the frame 32 and is located below one end of the scraper bar 33. The top opening of the slurry collection hopper 34 is located at the corresponding slurry gap. The bottom of the slurry collection hopper 34 is connected to one end of the diversion conduit 35. The other end of the diversion conduit 35 passes through the conveyor roller table 1 and the spraying mechanism 2 and is connected to the recycling mechanism 4.

[0038] The spraying device used sprays base slurry onto the bottom of the ceramic tile body on the conveyor roller table 1 via the spraying mechanism 2. Base slurry not adhering to the bottom of the tile body is recycled via the scraping mechanism 3 and the recycling mechanism 4. Specifically, the auxiliary conveyor belt 31 is mounted above the conveying surface of the conveyor roller table 1, running parallel to the conveyor roller table 1. The sprayed base slurry either adheres to the bottom of the tile body or to the bottom section of the auxiliary conveyor belt 31. Then, as the auxiliary conveyor belt 31 rotates, the adhered base slurry moves to the top section of the auxiliary conveyor belt 31, where it is scraped off by the scraping strip 33, preventing further adhesion. The scraping strip 33 extends to both sides of the frame 32, guiding the accumulated base slurry to the flow gap between the edge of the auxiliary conveyor belt 31 and the frame 32. The base slurry falls through the flow gap to the recycling mechanism 4 below for recycling, reducing slurry waste. If the sprayed slurry does not adhere to the bottom of the billet, it will immediately adhere to the auxiliary conveyor belt 31 and quickly transfer from the bottom belt section to the top belt section of the auxiliary conveyor belt 31, thus preventing the slurry from accumulating above the conveyor roller table 1 and preventing the slurry from adhering to the rollers and frame.

[0039] The auxiliary conveyor belt 31 rotates in a circular motion. The bottom section (lower half) of the auxiliary conveyor belt 31 is for receiving the attached slurry, while the top section (upper half) is the return section for scraping off the slurry. The conveying direction of the bottom section of the auxiliary conveyor belt 31 is the same as that of the conveyor roller table 1, i.e., both are conveyed from front to back. Therefore, the conveying direction of the top section of the auxiliary conveyor belt 31 is opposite, from back to front, and the attached slurry moves from back to front to the position of the scraper bar 33. Because the slurry on the auxiliary conveyor belt 31 is blocked by the scraper bar 33, it cannot move with the scraper bar 33 towards the front side of the scraper bar 33, and thus accumulates on the rear side of the scraper bar 33. The top section of the belt in front of the scraper bar 33 has no slurry attached and moves back to the top of the conveyor roller table 1 to receive new slurry. The scraper strip 33 is inclined to the left and right. One end of the scraper strip 33 is close to the front end of the auxiliary conveyor belt 31, and the other end of the scraper strip 33 is close to the rear end of the auxiliary conveyor belt 31. Under the drive of the auxiliary conveyor belt 31, the accumulated bottom slurry will flow to one end of the scraper strip 33. Therefore, the slurry collection hopper 34 is set below one end of the scraper strip 33 to collect the bottom slurry. The slurry collection hopper 34 is located between the upper and lower surfaces of the auxiliary conveyor belt 31 and does not interfere with the operation of the auxiliary conveyor belt 31 and the conveyor roller table 1. The bottom slurry in the slurry collection hopper 34 can be guided to the recycling mechanism 4 through the diversion conduit 35 for recycling.

[0040] Optionally, to more thoroughly remove the base slurry, at least two parallel scraper strips 33 can be installed, such as... Figure 4 As shown.

[0041] Furthermore, the conveying roller table 1 is provided with multiple rollers 11, such as... Figure 7 As shown, the roller 11 includes a roller body 111 and a spiral 112. The spiral 112 is spirally wound around the peripheral wall of the roller body 111. The thickness of the spiral 112 gradually decreases radially outward from the peripheral wall of the roller body 111 until it forms a pointed tip. This creates a trapezoidal surface with an approximately triangular cross-section. By using the spiral 112 with this structure to support the ceramic tile body, the contact area between the roller 11 and the ceramic tile body can be greatly reduced, allowing more base slurry to be sprayed directly onto the bottom of the tile body, thereby improving the consistency of the spraying. Moreover, the beveled edge of the spiral 112 facilitates the return of excess slurry on the roller 11 to the recycling mechanism 4.

[0042] Furthermore, such as Figure 2 and Figure 5As shown, the shotcrete mechanism 2 also includes a nozzle mounting bracket 22 and multiple slide rails 23. The multiple slide rails 23 are mounted on the base 12 of the conveying roller table 1. The roller 11 is rotatably mounted on the top of the base 12. The multiple slide rails 23 are located below the roller 11, and the multiple slide rails 23 and the roller 11 are parallel to each other. The nozzle mounting bracket 22 includes a connecting plate 220 and multiple slide bars 221. The multiple slide bars 221 correspond one-to-one with the multiple slide rails 23 and are slidably connected. One end of the multiple slide bars 221 is connected to the inner side of the connecting plate 220. The slide bars 221 have mounting slots 222 along their length. The nozzle 21 is mounted in the mounting slots 222 of the slide bars 221 by fasteners. The nozzles 21 on any two adjacent sliders 221 are staggered.

[0043] This forms a pull-out movable shotcrete mechanism 2. Multiple slide bars 221 are connected by a connecting plate 220. Pulling the connecting plate 220 allows all slide bars 221 to slide from the slide rail 23. The nozzle 21 is installed on the slide bar 221, making it easy to pull out for inspection or replacement without disassembling the shotcrete mechanism 2 or entering the base 12, and without stopping the conveyor roller table 1, achieving online, fast, and safe maintenance and inspection. The slide bar 221 has mounting slots 222 along its length. The nozzle 21 is installed in the mounting slots 222 of the slide bar 221 by fasteners, enabling detachable installation of the nozzle 21. This allows for adjustment of the position and number of nozzles according to the size and specifications of the blank, providing greater flexibility.

[0044] Optionally, such as Figure 6 As shown, the slurry supply step uses a slurry supply mechanism 5. The slurry supply mechanism 5 includes a slurry tank 51, a high-pressure pump 52, a main slurry supply pipe 53, and multiple slurry supply branch pipes 54. The outlet end of the slurry tank 51 is connected to the input end of the high-pressure pump 52, and the output end of the high-pressure pump 52 is connected to the input end of the main slurry supply pipe 53. The multiple output ends of the main slurry supply pipe 53 are connected to the input ends of the multiple slurry supply branch pipes 54 in a one-to-one correspondence. Each slide bar 221 is equipped with one slurry supply branch pipe 54. The nozzles 21 on the same slide bar 221 are connected in series to the same slurry supply branch pipe 54. Each slurry supply branch pipe 54 is equipped with a pressure reducing valve 55 at its output end.

[0045] The whitening base slurry for ceramic tiles is stored in a slurry tank 51. The slurry tank 51 can be equipped with a mixer to stir the base slurry. The base slurry is pumped to the main slurry supply pipe 53 by a high-pressure pump 52 (such as a piston high-pressure pump), and then distributed to each slurry supply branch pipe 54 by the main slurry supply pipe 53. Each slurry supply branch pipe 54 is equipped with a pressure reducing valve 55 at its output end to adjust the output pressure of the nozzle 21 on each slide bar 221, so as to achieve centralized slurry supply and pressure stabilization, avoid large fluctuations in the slurry supply pressure of each branch, and ensure that the pressure of each nozzle 21 is uniform and the atomization effect is consistent.

[0046] It should be noted that a high-pressure atomizing nozzle 21 is used to spray the slurry from bottom to top. The high-pressure pump 52 has a power of 2.0~2.5KW, and the working pressure of the nozzle 21 is approximately 30 bar (using a nozzle with a 0.43mm orifice). The amount of slurry in a 300mm×600mm disc is greater than 80g, with a specific gravity of 1.4. The pressure is stable with fluctuations ≤0.02Mpa, and the slurry is evenly adhered to the bottom surface of the green body, forming a slurry film of approximately 0.3mm. Figure 5 As shown, the input end of the nozzle 21 is on the side wall, with the nozzle facing upward. The slurry supply branch pipe 54 is connected to the input end of the corresponding nozzle 21 through a pipeline. The connected pipeline is not fixed but can be movable or moved to cooperate with the pull-out movement of the slide bar 221.

[0047] Specifically, in the shotcrete step, such as Figure 1 and Figure 2 As shown, the recycling mechanism 4 includes a recycling hopper 41 and a recycling output pipe 42. The recycling hopper 41 is installed on the base 12 and located below the multiple slide rails 23. The connecting plate 220 of the nozzle mounting bracket 22 is located below the slurry collection hopper 34. The bottom of the slurry collection hopper 34 is connected to one end of the drainage conduit 35. The other end of the drainage conduit 35 passes through the gap between the rollers 11 and the gap between the slide rails 23 in sequence and then connects to the recycling hopper 41. The base 12 is surrounded by a sealing plate 121, the base 12 has a maintenance port 122, the nozzle mounting bracket 22 is located in the maintenance port 122, and the connecting plate 220 movably closes the maintenance port 122. The bottom of the recovery output pipe 42 is connected to the bottom of the recovery hopper 41, and the recovery output pipe 42 is located below the maintenance port 122.

[0048] The recovery hopper 41 collects dripping slurry for recycling and to prevent pollution. A drainage conduit 35 is positioned between the roller 11 and the slide rail 23, without interfering with the operation or movement of the roller 11 and the slide bar 221. The slurry collected in the slurry collection hopper 34 is diverted to the recovery hopper 41 via the drainage conduit 35. The base 12 is enclosed by a sealing plate 121 to prevent slurry from splashing out during operation and polluting the environment; it also prevents dust and other impurities from entering the base 12 and contaminating the slurry. The base 12 has a maintenance port 122. When maintenance is required, the nozzle mounting bracket 22 can be pulled out through the maintenance port 122 via a pull-out structure (i.e., slide bar 221 and slide rail 23) for easy operation; when maintenance is not required, the nozzle mounting bracket 22 is pushed back into the base 12, and the maintenance port 122 can be closed via a connecting plate 220. For ease of operation, a handle 223 can be provided on the connecting plate 220. The bottom slurry collected in the recycling hopper 41 is output through the recycling output pipe 42 for subsequent recycling and reuse. The recycling output pipe 42 is located below the maintenance port 122 for easy operation by workers.

[0049] Furthermore, in the spraying step, the spiral body 112 of the roller 11 is made of rubber. Rubber has a certain elasticity, which can greatly reduce the phenomenon of roller marks on the bottom of the blank sprayed with the base slurry. Moreover, the rubber material is corrosion resistant, and the base slurry components are not easy to penetrate and form scale, reducing the problem of uneven base slurry thickness caused by scale on the roller surface.

[0050] Specifically, in the shotcrete step, the conveyor roller table 1 is equipped with a first drive motor 13, which drives the roller 11 to rotate, such as... Figure 2 As shown, the scraping mechanism 3 is equipped with a second drive motor 36, which drives the auxiliary conveyor belt 31 to rotate. Both the first drive motor 13 and the second drive motor 36 are conventional motors. The first drive motor 13 drives all rollers 11 to rotate synchronously through a conventional transmission or linkage mechanism, such as a synchronous belt or chain. Similarly, the second drive motor 36 also drives the auxiliary conveyor belt 31 to rotate through a conventional transmission or linkage mechanism. Optionally, the conveying roller table 1 and the auxiliary conveyor belt 31 have the same conveying speed for synchronous conveying, which can limit and prevent deviation of the tile movement.

[0051] The technical solution of the present invention will be further illustrated below through Examples 1 to 5 and Comparative Examples 1 to 2.

[0052] The raw materials for the ceramic tile whitening primers in Examples 1 to 5 are shown in Table 1 below, where the units are by mass percentage:

[0053] Table 1 The raw materials from Examples 1 to 5 were prepared according to the proportions shown in Table 1 to obtain a mixture. The mixture was then ball-milled until it reached the preset slurry parameters: a specific gravity of 2.5 g / cm³. 3 ~2.9 g / cm 3 The ceramic tile whitening base slurry is prepared by using a particle size of D50 = 5μm to 15μm and a flowability of 25 seconds to 40 seconds for the flow-out time of the Forte-4 cup.

[0054] Comparative Example 1 The formulation and preparation method of Comparative Example 1 are basically the same as those of Examples 1 to 5, except that, by mass percentage, the raw materials are 35% magnesium oxide powder, 52.5% talc powder, 0.3% suspending agent, 0.1% dispersant and 12.1% water.

[0055] Comparative Example 2 The formulation and preparation method of Comparative Example 2 are basically the same as those of Examples 1 to 5, except that a conventional ceramic tile base slurry formulation is used, namely: by mass percentage, the raw materials are 23% alumina powder, 2.0% magnesium oxide powder, 73.9% water, 0.8% suspending agent and 0.3% dispersant.

[0056] The slurries prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were all applied to the bottom of ceramic tile blanks with the same formula by spraying, and then fired. The fired tiles were tested according to the national standard testing methods for ceramic tiles or conventional testing methods for ceramic tiles. The test results are shown in Table 2 below, where whiteness refers to the whiteness of the bottom of the fired tile.

[0057] Table 2 In summary, the whitening base slurry for ceramic tiles, in addition to fulfilling the isolation and anti-sticking function of conventional ceramic tile base slurries, also lowers the melting temperature of the base slurry, forming an integrated sintered layer with the ceramic body. Furthermore, it can react with the alumina in the ceramic tile body to generate magnesium aluminum spinel, which has high crystal hardness and low coefficient of thermal expansion, significantly improving the whiteness and thermal stability of the tile base. By spraying the base slurry onto the surface of the ceramic body and then firing it for vitrification, the whiteness of the tile base can be increased by 10° or more without changing the ceramic body formula. This allows for the low-cost achievement of ultra-white ceramic tiles throughout, as shown in Examples 1 to 5.

[0058] The magnesium oxide powder ratio is set between 25.5% and 28.5%. If it exceeds this range, due to the high surface tension of MgO, it will react directly with SiO2 in the green body during the heating process of 800-1200℃ to form forsterite (2MgO•SiO2), or form cordierite with Al2O3 and SiO2 in the green body. This process releases heat in a concentrated manner, and the amount of liquid phase in a local area increases dramatically, resulting in defects such as bubbling and shrinkage, as shown in Comparative Example 1.

[0059] In conventional ceramic tile base slurry, as shown in Comparative Example 2, the slurry material cannot fully melt, diffuse, and chemically bond with the surface of the ceramic body during firing. The slurry layer is merely mechanically "attached" to the ceramic body; it does not melt, nor does it undergo redox reactions with the color-producing ions (Fe2O3, TiO2, etc.) in the ceramic body, nor does it form high-whiteness crystalline phases (such as the absence of magnesium aluminum spinel within the ceramic body). Therefore, it cannot "cover" the base color like adding a whitening agent inside the ceramic body. Furthermore, because the slurry layer fails to form an integrated sintered layer with the ceramic body, the density and continuity of the slurry isolation are poor. Under repeated exposure to high temperatures and roller pressure, the slurry layer is prone to localized cracking and peeling. Moreover, from... Figure 9 and Figure 10 The comparison shows that the whiteness of the bottom of the tile in Example 3 is significantly higher than that of the bottom of the tile in Comparative Example 2.

[0060] Other components and operations of the ceramic tile whitening base mortar and its application method according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0061] In the description of this specification, references to terms such as "embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A ceramic tile whitening base coat, characterized in that: The raw materials, by mass percentage, include 59.5%–66.5% talc powder, 25.5%–28.5% magnesium oxide powder, 0.3%–0.8% suspending agent, and 0.1%–0.3% dispersant, with the balance being water; The mass ratio of the talc powder to the magnesium oxide powder is 7:

3.

2. The ceramic tile whitening primer according to claim 1, characterized in that: The slurry parameters of the ceramic tile whitening primer include a specific gravity of 2.5 g / cm³. 3 ~2.9 g / cm 3 The particle size is D50 = 5μm to 15μm, and the flow rate is 25 seconds to 40 seconds for the Tu-4 cup.

3. The application method of the ceramic tile whitening primer according to claim 1 or 2, characterized in that, include: The preparation steps involve mixing the raw materials according to a predetermined ratio to obtain a mixture, and then ball milling the mixture until the preset slurry parameters are achieved to obtain the ceramic tile whitening base slurry. In the slurry supply step, the prepared ceramic tile whitening base slurry is transported to a slurry tank, and water is added to the slurry tank to mix until the specific gravity of the ceramic tile whitening base slurry is 1.05 g / cm³. 3 ~1.15 g / cm 3 ; In the spraying step, a base slurry spraying device is used to spray the tile whitening base slurry from the slurry supply step onto the bottom surface of the tile body to be fired. The base slurry spraying device includes a conveying roller table and a spraying mechanism. The spraying mechanism is located below the conveying roller table and has multiple nozzles. The nozzles of the nozzles face upwards, and the multiple nozzles are spaced apart and staggered to form a cross-shaped grid distribution. The conveying roller table transports the tile body to be fired, and the slurry tank pumps the tile whitening base slurry to the spraying mechanism. The nozzles are atomizing nozzles, and the nozzles spray the tile whitening base slurry onto the bottom surface of the tile body that they pass over. The working pressure of the nozzles is 30 bar.

4. The method for applying the ceramic tile whitening primer according to claim 3, characterized in that: The spraying device also includes a scraping mechanism and a recovery mechanism, with the recovery mechanism installed below the spraying mechanism; The scraping mechanism includes an auxiliary conveyor belt, a frame, a scraper strip, a slurry collection hopper, and a flow guide pipe. The auxiliary conveyor belt is mounted above the conveying surface of the conveying roller table via the frame. The bottom section of the auxiliary conveyor belt and the conveying surface of the conveying roller table are vertically opposite each other to form a brick-moving space. The conveying direction of the bottom section of the auxiliary conveyor belt is the same as the conveying direction of the conveying roller table. The scraper strip is located above the auxiliary conveyor belt. Both ends of the scraper strip are connected to the frame. The bottom of the scraper strip abuts against the top section of the auxiliary conveyor belt. Slurry flow gaps are left between the two sides of the auxiliary conveyor belt and the frame. The scraper is inclined to the left and right, with one end of the scraper close to the front end of the auxiliary conveyor belt and the other end close to the rear end of the auxiliary conveyor belt. The slurry collection hopper is installed on the frame and located below one end of the scraper, with the top opening of the slurry collection hopper located at the corresponding slurry flow gap. The bottom of the slurry collection hopper is connected to one end of the diversion conduit, and the other end of the diversion conduit passes through the conveyor roller table and the spraying mechanism and then connects to the recycling mechanism.

5. The application method of the ceramic tile whitening primer according to claim 3, characterized in that: The conveying roller table is provided with multiple roller bars, each roller bar including a roller bar body and a spiral body. The spiral body is spirally wound around the peripheral wall of the roller bar body, and the thickness of the spiral body gradually decreases radially outward from the peripheral wall of the roller bar body to form a tip.

6. The method for applying the ceramic tile whitening primer according to claim 4, characterized in that: The shotcrete mechanism also includes a nozzle mounting bracket and multiple slide rails. The multiple slide rails are mounted on the base of the conveying roller table, the roller is rotatably mounted on the top of the base, the multiple slide rails are located below the roller, and the multiple slide rails and the roller are parallel to each other. The nozzle mounting bracket includes a connecting plate and multiple slide bars. The multiple slide bars correspond one-to-one with the multiple slide rails and are slidably connected. One end of the multiple slide bars is connected to the inner side of the connecting plate. The slide bars have mounting slots along their length. The nozzle is mounted in the mounting slots of the slide bars by fasteners. The nozzles on any two adjacent sliders are staggered.

7. The method for applying the ceramic tile whitening primer according to claim 6, characterized in that: The slurry supply step uses a slurry supply mechanism, which includes a slurry tank, a high-pressure pump, a main slurry supply pipe, and multiple slurry supply branch pipes. The outlet end of the slurry tank is connected to the input end of the high-pressure pump, and the output end of the high-pressure pump is connected to the input end of the main slurry supply pipe. The multiple output ends of the main slurry supply pipe are connected to the input ends of the multiple slurry supply branch pipes in a one-to-one correspondence. Each slide bar is equipped with one slurry supply branch pipe, and the nozzles on the same slide bar are connected in series to the same slurry supply branch pipe. Each slurry supply branch pipe is equipped with a pressure reducing valve at its output end.

8. The method for applying the ceramic tile whitening primer according to claim 7, characterized in that: In the shotcrete step, the recycling mechanism includes a recycling hopper and a recycling output pipe. The recycling hopper is installed on the base and located below the multiple slide rails. The connecting plate of the nozzle mounting bracket is located below the slurry hopper. The bottom of the slurry hopper is connected to one end of the drainage conduit. The other end of the drainage conduit passes through the gap between the rollers and the gap between the slide rails in sequence and then connects to the recovery hopper. The base is surrounded by sealing plates, and the base has a maintenance port. The nozzle mounting bracket is located in the maintenance port, and the connecting plate can be moved to close the maintenance port. The recovery output pipe is connected to the bottom of the recovery hopper, and the recovery output pipe is located below the maintenance port.

9. The method for applying the ceramic tile whitening primer according to claim 8, characterized in that: In the shotcrete step, the spiral body of the roller used is made of rubber.

10. The method for applying the ceramic tile whitening primer according to claim 8, characterized in that: In the shotcrete step, the conveyor roller table is equipped with a first drive motor, which drives the roller to rotate; the scraping mechanism is equipped with a second drive motor, which drives the auxiliary conveyor belt to rotate.

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