Praseodymium pigment, preparation method of praseodymium pigment and method for preparing green decorative ceramic plate by using pure ammonia atmosphere

Abstract

The invention belongs to the field of architectural ceramics, and relates to a praseodymium pigment, a preparation method of the praseodymium pigment and a method for preparing a green decorative ceramic plate by using a pure ammonia atmosphere. The praseodymium pigment has a core-shell structure with zirconium silicate as a core and borosilicate glass with uniformly distributed + 3 valence Pr ions as a shell. The zirconium silicate matrix has excellent high-temperature stability, so that the formed green pigment with the core-shell structure has relatively excellent high-temperature-resistant stability and is not easily eroded by other glazes in a high-temperature use process, and a decorative ceramic product has relatively good stereoscopic impression, is flat in surface and has no obvious air holes.

Description

Technical Field

[0001] The invention belongs to the field of building ceramics, and relates to a praseodymium colorant, a method for preparing the praseodymium colorant, and a method for preparing a green decorative ceramic plate by using a pure ammonia atmosphere. Background Art

[0002] The Color Pigments Manufacturers Association (CPMA) displays a variety of common green pigments, including Cr 2 O 3 (3-05-3), Ca 3 Cr 2 Si 3 O 12 (4-07-3), Ni 2 SiO 4 (5-45-3), Co(AlCr) 2 O 4 (13-29-2), CoCr 2 O 4 (13-30-3), Co 2 TiO 4 (13-31-3) etc. These pigments use heavy metals such as Ni, Co, and Cr as coloring units. However, heavy metal ions (especially hexavalent chromium ions) are highly toxic and pose a potential threat to the environment and human health.

[0003] Rare earth oxides have a rich 4f electron layer structure. In the visible light range, the energy level transition of 4f electrons can absorb light of a specific wavelength, thereby producing color. It is non-toxic and harmless and is an environmentally friendly coloring oxide. Praseodymium oxide is a common coloring oxide. At present, the building ceramics industry uses zirconium silicate as the matrix and obtains colorful zirconium praseodymium yellow pigments by doping praseodymium oxide. There are no reports on green praseodymium ceramic pigments. Summary of the invention

[0004] In view of the above problems, the present invention provides a core-shell structured praseodymium colorant, a method for preparing the praseodymium colorant, and a method for preparing a green decorative ceramic plate using a pure ammonia atmosphere. Since the zirconium silicate matrix has excellent high temperature stability, the green colorant with a core-shell structure formed also has excellent high temperature stability. During high temperature use, it is not easily corroded by other glazes. The decorative ceramic product has a good three-dimensional sense, and the surface is flat and has no obvious pores.

[0005] In a first aspect, the present invention provides a praseodymium-based colorant having a core-shell structure with zirconium silicate as a core and borosilicate glass with +3-valent Pr ions uniformly distributed as a shell.

[0006] In a second aspect, the present invention provides a method for preparing a praseodymium-based colorant. The method for preparing the praseodymium-based colorant comprises: x Zr 1-x SiO 4 Praseodymium oxide, silicon dioxide and zirconium oxide are weighed in a stoichiometric ratio of (0<x ≤ 0.08), and then a boron frit is added, mixed thoroughly, and dried to form a powder; the powder is then sintered and crushed to obtain the praseodymium-based colorant.

[0007] Preferably, the chemical composition of the boron frit includes: in terms of mass percentage, Al 2 O 3 :7.8%~12%,SiO 2 :30%~41%,Fe 2 O 3 :0.05%~0.2%, CaO: 0.15%~0.5%, K 2 O: 5.5%~6.5%, Na 2 O: 14%~17%, B 2 O 3 : 28%~32%, BaO: 0.15%~0.35%.

[0008] Preferably, the amount of the boron frit is 3% to 8% of the total mass of praseodymium oxide, silicon dioxide and zirconium oxide.

[0009] Preferably, the sintering comprises: keeping the temperature at 900-1000° C. for 1-2 hours, and then keeping the temperature at 1250-1350° C. for 1.5-2.5 hours.

[0010] In a third aspect, the present invention provides a method for preparing a green decorative ceramic plate using a pure ammonia atmosphere. The method comprises the following steps: inkjet printing a common ink pattern on the surface of a brick; positioning an inkjet printed glue pattern on the surface of the brick after the common ink pattern is inkjet printed; spreading the praseodymium colorant on the surface of the brick after the inkjet printed glue pattern is positioned; applying a dry granular glaze on the surface of the brick after the praseodymium colorant is spread; and firing and polishing the brick after the dry granular glaze is applied in a pure ammonia atmosphere to obtain the green decorative ceramic plate.

[0011] Preferably, the particle size of the praseodymium-based colorant is 20 mesh to 40 mesh.

[0012] Preferably, the chemical composition of the dry granular glaze includes: SiO 2 :50%~61%,Al 2 O 3 :9.5%~15%,Fe 2 O 3:0.05%~0.2%, CaO: 6.5%~12%, MgO: 0.85%~1.2%, K 2 O: 4.5%~6.3%, Na 2 O: 1.8%~2.2%, P 2 O 5 :0.15%~0.3%, ZnO: 5.5%~9.5%.

[0013] Preferably, the dry granular glaze is applied by pouring glaze; preferably, the specific gravity of the dry granular glaze is 1.45-1.55 g / cm 3 , glaze application amount is 960 ~1100g / m 2 .

[0014] Preferably, the grayscale of the glue pattern is 30% to 40%.

[0015] Preferably, the sintering temperature is 1130-1180° C., and the sintering period is 40-45 minutes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a physical picture of the praseodymium-based color materials of Examples 1-2 and Comparative Examples 1-2.

[0017] Figure 2 This is a SEM picture of the praseodymium-based colorant of Example 2.

[0018] Figure 3 This is the XRD pattern of the praseodymium color material of Example 2.

[0019] Figure 4 It is a brick surface effect diagram of the green decorative ceramic plate of Example 5.

[0020] Figure 5 This is a brick surface effect diagram of the decorative ceramic plate of Example 3. DETAILED DESCRIPTION

[0021] The present invention is further described by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention. The following is an exemplary description of the praseodymium colorant, a method for preparing the praseodymium colorant, and a method for preparing a green decorative ceramic plate using a pure ammonia atmosphere according to the present invention.

[0022] As mentioned above, the present invention provides a novel praseodymium-based colorant. The praseodymium-based colorant has a core-shell structure with zirconium silicate as the core and borosilicate glass with +3-valent Pr ions uniformly distributed as the shell. The borosilicate glass is wrapped on the surface of the zirconium silicate. The +3-valent Pr ions in the core-shell structure serve as coloring centers to produce green.

[0023] According to Pr x Zr1-x SiO 4 Praseodymium oxide, silicon dioxide, and zirconium oxide are weighed in a stoichiometric ratio of (0<x≤0.08). Praseodymium oxide, silicon dioxide, zirconium oxide and an appropriate amount of boron frit are fully ground and dispersed, and then dried to make powder. The amount of the boron frit used may be 3% to 8% of the total mass of praseodymium oxide, silicon dioxide, and zirconium oxide. If the amount of the boron frit is too low, the borosilicate glass will not be able to fully wrap the zirconium silicate matrix, resulting in the production of yellow colorant. If the amount of the boron frit is too high, the network structure of the glass will be unstable, forming a non-uniform phase, causing uneven coloring, and at the same time aggravating the agglomeration effect of the colorant particles, which is not conducive to dispersion.

[0024] In some embodiments, the chemical composition of the boron frit includes: in mass percentage, Al 2 O 3 :7.8%~12%,SiO 2 :30%~41%,Fe 2 O 3 :0.05%~0.2%, CaO: 0.15%~0.5%, K 2 O: 5.5%~6.5%, Na 2 O: 14%~17%, B 2 O 3 :28%~32%, BaO:0.15%~0.35%. Controlling the chemical composition of the boron frit within the above range can accelerate the nucleation of zirconium silicate. In addition, this can reasonably control the high-temperature viscosity of the boron frit, and in the process of positioning the glue dry particles and applying the praseodymium series colorant dry particles and then covering the dry particle glaze, it can reduce the occurrence of defects such as blisters, pinholes, and concave glaze.

[0025] The powder is placed in a sagger and sintered at a suitable temperature. The sintering system includes: keeping the temperature at 900-1000°C for 1-2 hours, and then keeping the temperature at 1250-1350°C for 1.5-2.5 hours. For example, the sintering temperature system is: first heating to 1000°C, keeping the temperature for 1 hour, and then heating to 1250-1350°C and keeping the temperature for 1.5 hours.

[0026] During the synthesis of the praseodymium-based pigment, the presence of the boron frit is beneficial to lowering the synthesis temperature of the solid phase reaction. When the sintering temperature is raised to about 900-1000°C, silicon dioxide and zirconium oxide react to form zirconium silicate through high temperature, while the boron frit is wrapped around the surface of the zirconium silicate particles in the form of borosilicate glass to form inclusions. At this time, the praseodymium ions in the zirconium silicate lattice mainly present a +4 valence, and the overall color tone is yellowish. Continue to increase the sintering temperature to 1250-1350°C, and the praseodymium ions undergo a high temperature transformation, Pr 4+ Convert to Pr 3+ , and migrates into the shell of borosilicate glass and is retained, forming a green colored center.

[0027] The sintered praseodymium pigment is crushed into a certain particle size.

[0028] The following is an exemplary description of a method for preparing a green decorative ceramic plate using a pure ammonia atmosphere.

[0029] The brick green powder is pressed and formed into a brick green. The brick green powder commonly used in the art can be used. For example, but not limited to this, the chemical composition of the brick green powder includes: in mass percentage, SiO 2 :60~70%,Al 2 O 3 :19~25%,Fe 2 O 3 :0.5~1.5%, TiO 2 :0.2~0.5%, CaO: 0.2~0.8%, MgO: 0.3~0.8%, K 2 O: 2.0~4.0%, Na 2 O: 1.5~3.5%, loss on ignition: 4.0~6.0%.

[0030] The pressing machine can be used for pressing. The molding method includes but is not limited to dry pressing.

[0031] The bricks are dried. The moisture content of the dried bricks can be controlled within 0.2-0.5wt%. The drying temperature can be 110-130°C. The drying time can be 0.5-1.5 hours.

[0032] The ordinary ink pattern is printed on the surface of the brick. The texture and color of the ordinary ink pattern printed by inkjet can be adaptively changed according to the needs. The ink pattern can be formed by inkjet printing ordinary ink through an inkjet machine.

[0033] Position the inkjet-printed glue pattern on the surface of the brick blank after the ordinary ink pattern is inkjet-printed. That is, use an inkjet printer to print a suitable amount of grayscale glue at the location where the colorant needs to be bonded. The glue pattern can be printed using an inkjet printer. The glue pattern can be printed by dual-channel inkjet printing. The grayscale of the glue pattern of each channel can be independently 30%~40%. By controlling the grayscale of the glue pattern within the above range, the amount of glue used can be controlled. Preferably, the amount of glue applied is less than 20g / m 2 .

[0034] The praseodymium colorant is applied on the surface of the brick after the glue pattern is inkjet printed. The new praseodymium colorant crushed to a certain particle size is evenly spread on the surface of the brick, so that the praseodymium colorant is bonded to the surface of the brick in the area where the glue is printed, and the praseodymium colorant in the area where the glue is not printed is not bonded by the glue and is recovered for standby use, thereby realizing the application of colorant using the digital glue positioning process. A dry particle distributor can be used to apply the colorant.

[0035] After the colorant is applied, a fan is used to remove the unadhered praseodymium colorant and recover it. The amount of the praseodymium colorant applied can be 150-200 g / m 2 If the amount of praseodymium pigment applied is too little, the green tone will be weak. If the amount of praseodymium pigment applied is too much, it will easily cause the glaze surface to be uneven.

[0036] The particle size of the praseodymium colorant is preferably controlled within 20-40 meshes. If the particle size of the praseodymium colorant is too small, the color of the bonding particles is not obvious enough. If the particle size of the praseodymium colorant is too large, it will protrude from the glaze layer, causing glaze surface defects.

[0037] Apply dry granular glaze on the surface of the brick after applying praseodymium series colorant.

[0038] In some embodiments, the chemical composition of the dry granular glaze includes: SiO 2 :50%~61%,Al 2 O 3 :9.5%~15%,Fe 2 O 3 :0.05%~0.2%, CaO: 6.5%~12%, MgO: 0.85%~1.2%, K 2 O: 4.5%~6.3%, Na 2 O: 1.8%~2.2%, P 2 O 5 :0.15%~0.3%, ZnO:5.5%~9.5%. Due to the low initial melting point of borosilicate glass, the silicon content of dry granular glaze is controlled at 50%~61%, the aluminum content is controlled at 9.5%~15%, and the zinc content is controlled at 5.5%~9.5%. This can improve the high-temperature fluidity of dry granular glaze and prevent defects such as pores from occurring during the fusion process of praseodymium-based colorants and dry granular glaze.

[0039] Preferably, the chemical composition of the dry granular glaze includes: SiO 2 :55%~60%,Al 2 O 3 :10%~12%,Fe 2 O 3 :0.05%~0.1%, CaO: 6.5%~12%, MgO: 0.85%~1.2%, K 2 O: 4.5%~6.3%, Na 2 O: 1.8%~2.2%, P 2 O 5 :0.15%~0.3%, ZnO: 8%~9.5%.

[0040] The dry granular glaze is applied by pouring glaze. Preferably, the specific gravity of the dry granular glaze is 1.45-1.55 g / cm 3 , glaze application amount is 960~1100 g / m 2 By controlling the specific gravity and glazing amount of the dry granular glaze within the above range, the flow rate and usage of the dry granular glaze can be reasonably controlled, so that the brick surface has an excellent three-dimensional effect and the brick surface has no obvious glaze defects.

[0041] The bricks after applying the dry granular glaze are dried.

[0042] The dried bricks are sent to the kiln. The firing atmosphere of the kiln is ammonia. The firing temperature is 1130-1180°C and the firing cycle is 40-45 minutes. By controlling the appropriate firing temperature and firing cycle, the discharge of pores can be promoted and the glaze surface can be ensured to be smooth. In particular, in a pure ammonia kiln, the main products of pure ammonia combustion are nitrogen and water, which is very important for Pr 3+ It has a protective effect on the stability and color development of the green. That is, when ammonia is burned as a fuel, the main products produced are nitrogen and water. When the main product of the flue gas during high-temperature firing is nitrogen, it plays a protective role in the atmosphere to a certain extent, preventing the conversion of +3 praseodymium ions to +4 valence, and enhancing the green coloring effect. Moreover, when ammonia is burned as a fuel, the main products produced are nitrogen and water, and no carbon dioxide is produced. Therefore, it is regarded as a clean fuel that helps reduce greenhouse gas emissions.

[0043] Polishing and edge grinding give ceramic plate products.

[0044] In summary, the praseodymium colorant of the present invention has a unique core-shell structure of borosilicate glass phase encapsulating zirconium silicate particles, is environmentally friendly and non-toxic, has good high temperature resistance and chemical stability, improves the high temperature stability of the praseodymium colorant, can assist the glaze surface to melt quickly, reduces the generation of bubbles during high temperature firing, and effectively improves the surface quality of the product. Moreover, the present invention is combined with the characteristics of ammonia combustion without carbon emissions, which is conducive to obtaining a new type of environmentally friendly ceramic plate product.

[0045] The following examples are further listed to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0046] Example 1

[0047] Preparation of praseodymium pigments. According to the stoichiometric ratio of Prx Zr 1-x SiO 4 (x=0.07) Weigh praseodymium oxide, silicon dioxide, and zirconium oxide, then add boron frit, grind and disperse them thoroughly, dry and make powder, then put the powder into a sagger, sinter at a suitable temperature, and break it into a certain particle size for use. The chemical composition of the boron frit includes: in mass percentage, Al 2 O 3 :9.1%,SiO 2 :38%,Fe 2 O 3 :0.11%,CaO:0.45%,K 2 O: 6.1%, Na 2 O: 15.7%, B 2 O 3 : 30.3%, BaO: 0.24%. The amount of the boron frit is 5% of the total mass of praseodymium oxide, silicon dioxide and zirconium oxide. The sintering temperature system is to first heat to 1000°C, keep it warm for 1.5 hours, and then heat to 1350°C and keep it warm for 2 hours.

[0048] Example 2

[0049] Preparation of praseodymium pigments. According to the stoichiometric ratio of Pr x Zr 1-x SiO 4 (x=0.08) Weigh praseodymium oxide, silicon dioxide, and zirconium oxide, then add boron frit, grind and disperse them thoroughly, dry and make powder, then put the powder into a sagger, sinter at a suitable temperature, and break it into a certain particle size for use. The chemical composition of the boron frit includes: in mass percentage, Al 2 O 3 :9.3%,SiO 2 :38%,Fe 2 O 3 :0.09%,CaO:0.42%,K 2 O: 5.95%, Na 2 O: 15.7%, B 2 O 3 : 30.3%, BaO: 0.24%. The amount of the boron frit is 8% of the total mass of praseodymium oxide, silicon dioxide and zirconium oxide. The sintering temperature system is to first heat to 1000°C, keep it warm for 1.5 hours, and then heat to 1350°C and keep it warm for 2 hours.

[0050] Example 3

[0051] Preparation of praseodymium pigments. According to the stoichiometric ratio of Pr x Zr 1-x SiO 4(x=0.06) Weigh praseodymium oxide, silicon dioxide, and zirconium oxide, then add boron frit, grind and disperse them thoroughly, dry and make powder, then put the powder into a sagger, sinter at a suitable temperature, and break it into a certain particle size for use. The chemical composition of the boron frit includes: in mass percentage, Al 2 O 3 :11.1%,SiO 2 :35.2%,Fe 2 O 3 :0.15%,CaO:0.36%,K 2 O: 5.75%, Na 2 O: 15.2%, B 2 O 3 : 32%, BaO: 0.24%. The amount of the boron frit is 3% of the total mass of praseodymium oxide, silicon dioxide and zirconium oxide. The sintering temperature system is to first heat to 900°C, keep it warm for 1 hour, and then heat to 1250°C and keep it warm for 1.5 hours.

[0052] Example 4

[0053] Preparation of praseodymium pigments. According to the stoichiometric ratio of Pr x Zr 1-x SiO 4 (x=0.08) Weigh praseodymium oxide, silicon dioxide, and zirconium oxide, then add boron frit, grind and disperse them thoroughly, dry and make powder, then put the powder into a sagger, sinter at a suitable temperature, and break it into a certain particle size for use. The chemical composition of the boron frit includes: in mass percentage, Al 2 O 3 :9.2%,SiO 2 :38.2%,Fe 2 O 3 :0.12%,CaO:0.45%,K 2 O: 5.95%, Na 2 O: 15.97%, B 2 O 3 : 29.8%, BaO: 0.31%. The amount of the boron frit is 5% of the total mass of praseodymium oxide, silicon dioxide and zirconium oxide. The sintering temperature system is to first heat to 1000°C, keep it warm for 1 hour, and then heat to 1250°C and keep it warm for 1.5 hours.

[0054] Comparative Example 1 It is basically the same as Example 1, except that the amount of the boron frit used is 1% of the total mass of praseodymium oxide, silicon dioxide and zirconium oxide.

[0055] Comparative Example 2 It is basically the same as Example 1, except that: the sintering temperature system is to first increase the temperature to 700° C., keep it at that temperature for 1 hour, and then increase the temperature to 1100° C. and keep it at that temperature for 1.5 hours.

[0056] Figure 1 The following are the actual pictures of the praseodymium colorants of Examples 1-2 and Comparative Examples 1-2 (from left to right, respectively, Examples 1-2 and Comparative Examples 1-2). It can be seen that the amount of boron frit used in Comparative Example 1 is relatively low, and the obtained powder is still a yellow colorant. The sintering temperature of Comparative Example 2 is relatively low, resulting in only a small amount of +4-valent praseodymium ions being converted into +3-valent praseodymium ions, and the color of the obtained colorant is still yellowish. Compared with the comparative example, each embodiment increases the content of the boron frit and increases the sintering temperature, and the obtained praseodymium colorant is green.

[0057] Figure 2 This is a SEM image of the praseodymium-based pigment of Example 2. Figure 3 This is the XRD diagram of the praseodymium-based colorant of Example 2. It can be seen that the main crystalline phase of the sample is zirconium silicate, and there are incompletely reacted silicon oxide and zirconium oxide. XRD proves that the crystalline phase is zirconium silicate, and SEM proves that the zirconium silicate is wrapped by the borosilicate glass phase. Combining the SEM and XRD results, it is shown that a core-shell structure of borosilicate-wrapped zirconium silicate is formed. Since the main crystalline phase is zirconium silicate, the glass phase formed by the boron frit is borosilicate glass. In addition, the ionic radius of the trivalent praseodymium ion is much larger than that of the zirconium ion, so the trivalent praseodymium ion basically cannot exist in the zirconium silicate lattice, but can only be in the borosilicate glass phase.

[0058] Example 5

[0059] A method for preparing a green decorative ceramic plate using a pure ammonia atmosphere comprises the following steps: Step 1. Prepare a green brick: Press the green brick powder into a shape to obtain a green brick.

[0060] Step 2. Inkjet print ordinary ink patterns on the surface of the brick.

[0061] Step 3. Positioning an inkjet-printed glue pattern on the surface of the brick blank after the inkjet-printed ordinary ink pattern. The grayscale of the glue pattern is 40%.

[0062] Step 4. Spread praseodymium colorant on the surface of the brick after positioning the inkjet printed glue pattern. x Zr 1-x SiO 4 (x=0.07) Weigh praseodymium oxide, silicon dioxide, and zirconium oxide, then add boron frit, grind and disperse them thoroughly, dry and make powder, then put the powder into a sagger, sinter at a suitable temperature, and break it into a certain particle size for use. The chemical composition of the boron frit includes: in mass percentage, Al 2 O 3:9.1%,SiO 2 :38%,Fe 2 O 3 :0.11%,CaO:0.45%,K 2 O: 6.1%, Na 2 O: 15.7%, B 2 O 3 : 30.3%, BaO: 0.24%. The amount of the boron frit is 5% of the total mass of praseodymium oxide, silicon dioxide and zirconium oxide. The sintering temperature system is to first heat to 1000°C, keep it warm for 1.5 hours, and then heat to 1350°C and keep it warm for 2 hours. The particle size of the praseodymium colorant is 30 mesh.

[0063] Step 5. Apply dry granular glaze on the surface of the brick after spreading the praseodymium colorant. The chemical composition of the dry granular glaze includes: SiO 2 :60.5%,Al 2 O 3 :11.5%,Fe 2 O 3 :0.12%, CaO: 9.86%, MgO: 1.08%, K 2 O: 5.28%, Na 2 O: 2.18%, P 2 O 5 :0.28%,ZnO:9.2%. The dry granular glaze is applied by pouring glaze. The specific gravity of the dry granular glaze is 1.55g / cm 3 , application amount is 1050g / m 2 .

[0064] Step 6. Put the bricks after applying the dry granular glaze into the kiln for firing. The firing temperature is 1180° C., the firing cycle is 45 minutes, and the firing atmosphere of the kiln is ammonia.

[0065] Step 7. Polishing.

[0066] Figure 4 This is a brick surface effect diagram of the green decorative ceramic plate of Example 5. It can be seen that the ceramic plate sample presents a distinct green color, has an excellent three-dimensional sense, and has a smooth surface without obvious pores.

[0067] Comparative Example 3 A method for preparing a green decorative ceramic plate using a pure ammonia atmosphere comprises the following steps: Step 1. Prepare a green brick: Press the green brick powder into a shape to obtain a green brick.

[0068] Step 2. Inkjet print ordinary ink patterns on the surface of the brick.

[0069] Step 3. Positioning an inkjet-printed glue pattern on the surface of the brick blank after the inkjet-printed ordinary ink pattern. The grayscale of the glue pattern is 30%.

[0070] Step 4. Spread praseodymium colorant on the surface of the brick after positioning the inkjet printed glue pattern. x Zr 1-x SiO 4 (x=0.07) Weigh praseodymium oxide, silicon dioxide, and zirconium oxide, then add boron frit, grind and disperse them thoroughly, dry and make powder, then put the powder into a sagger, sinter at a suitable temperature, and break it into a certain particle size for use. The chemical composition of the boron frit includes: in mass percentage, Al 2 O 3 :9.1%,SiO 2 :38%,Fe 2 O 3 :0.11%,CaO:0.45%,K 2 O: 6.1%, Na 2 O: 15.7%, B 2 O 3 : 30.3%, BaO: 0.24%. The amount of the boron frit is 5% of the total mass of praseodymium oxide, silicon dioxide and zirconium oxide. The sintering temperature system is to first heat to 1000°C, keep it warm for 1.5 hours, and then heat to 1350°C and keep it warm for 2 hours. The particle size of the praseodymium colorant is 30 mesh.

[0071] Step 5. Apply dry granular glaze on the surface of the brick after the colorant is applied. The chemical composition of the dry granular glaze includes: SiO 2 :62.9%,Al 2 O 3 7.5%,Fe 2 O 3 :0.2%, CaO: 13.5%, MgO: 0.7%, K 2 O: 3.8%, Na 2 O: 6.4%, P 2 O 5 :0.5%,ZnO:4.5%. The dry granular glaze is applied by pouring glaze. The specific gravity of the dry granular glaze is 1.45g / cm 3 , application amount is 1000g / m 2 .

[0072] Step 6. Put the bricks after applying the dry granular glaze into the kiln for firing. The firing temperature is 1180° C., the firing cycle is 45 minutes, and the firing atmosphere of the kiln is ammonia.

[0073] Step 7. Polishing.

[0074] Figure 5 This is a brick surface effect diagram of the decorative ceramic board of Example 3. It can be seen that there are obvious white pores on the surface of the ceramic board sample, and the overall color is dark.

[0075] Comparative Example 4 A method for preparing a green decorative ceramic plate using a pure ammonia atmosphere comprises the following steps: Step 1. Prepare a green brick: Press the green brick powder into a shape to obtain a green brick.

[0076] Step 2. Inkjet print ordinary ink patterns on the surface of the brick.

[0077] Step 3. Positioning an inkjet-printed glue pattern on the surface of the brick blank after the inkjet-printed ordinary ink pattern. The grayscale of the glue pattern is 30%.

[0078] Step 4. Spread praseodymium colorant on the surface of the brick after positioning the inkjet printed glue pattern. x Zr 1-x SiO 4 (x=0.08) Weigh praseodymium oxide, silicon dioxide, and zirconium oxide, then add boron frit, grind and disperse them thoroughly, dry and make powder, then put the powder into a sagger, sinter at a suitable temperature, and break it into a certain particle size for use. The chemical composition of the boron frit includes: in mass percentage, Al 2 O 3 :3.5%,SiO 2 :41.3%,Fe 2 O 3 :0.29%,CaO:0.92%,K 2 O: 3.03%, Na 2 O: 8.5%, B 2 O 3 :42%,BaO:0.46%. The amount of the boron frit is 8% of the total mass of praseodymium oxide, silicon dioxide, and zirconium oxide. The sintering temperature system is to first heat to 1000℃, keep it warm for 1.5 hours, and then heat to 1350℃ and keep it warm for 2 hours. The particle size of the praseodymium colorant is 30 mesh.

[0079] Step 5. Apply dry granular glaze on the surface of the brick after spreading the praseodymium colorant. The chemical composition of the dry granular glaze includes: SiO 2 :60.5%,Al 2 O 3 :11.5%,Fe 2 O 3 :0.12%, CaO: 9.86%, MgO: 1.08%, K 2 O: 5.28%, Na 2O: 2.18%, P 2 O 5 :0.28%,ZnO:9.2%. The dry granular glaze is applied by pouring glaze. The specific gravity of the dry granular glaze is 1.55g / cm 3 , application amount is 1050g / m 2 .

[0080] Step 6. Put the bricks after applying the dry granular glaze into the kiln for firing. The firing temperature is 1180° C., the firing cycle is 45 minutes, and the firing atmosphere of the kiln is ammonia.

[0081] Step 7. Polishing.

[0082] In this comparative example, due to the improper chemical composition of the boron frit, although a core-shell structure of borosilicate glass encapsulating zirconium silicate is formed, it is easy to cause surface concave glaze defects.

Claims

1. A praseodymium colorant, characterized in that: The praseodymium-based colorant has a core-shell structure with zirconium silicate as a core and borosilicate glass with +3-valent Pr ions uniformly distributed as a shell.

2. The method for preparing the praseodymium colorant according to claim 1, characterized in that: The preparation method of the praseodymium colorant comprises: x Zr 1-x Praseodymium oxide, silicon dioxide and zirconium oxide are weighed in a stoichiometric ratio of SiO4 (0<x ≤ 0.08), and then a boron frit is added, mixed thoroughly, and then dried to form a powder; the powder is then sintered and crushed to obtain the praseodymium-based colorant.

3. The preparation method according to claim 2, characterized in that: The chemical composition of the boron frit includes, by mass percentage, Al2O3: 7.8%~12%, SiO2: 30%~41%, Fe2O3: 0.05%~0.2%, CaO: 0.15%~0.5%, K2O: 5.5%~6.5%, Na2O: 14%~17%, B2O3: 28%~32%, and BaO: 0.15%~0.35%.

4. The preparation method according to claim 2, characterized in that: The amount of the boron frit used is 3% to 8% of the total mass of praseodymium oxide, silicon dioxide and zirconium oxide.

5. The preparation method according to claim 2, characterized in that: The sintering comprises: keeping the temperature at 900-1000° C. for 1-2 hours, and then keeping the temperature at 1250-1350° C. for 1.5-2.5 hours.

6. A method for preparing green decorative ceramic panels using pure ammonia atmosphere, characterized in that: The method comprises the following steps: Inkjet printing of ordinary ink patterns on the surface of the brick; Positioning an inkjet-printed glue pattern on the surface of the brick blank after the inkjet-printed ordinary ink pattern; Spreading the praseodymium colorant according to claim 1 on the surface of the brick after positioning the inkjet-printed glue pattern; Applying dry granular glaze on the surface of the brick after spreading the praseodymium series colorant; The green decorative ceramic plate is obtained by firing and polishing the green brick after applying the dry granular glaze in a pure ammonia atmosphere.

7. The method according to claim 6, characterized in that The particle size of the praseodymium colorant is 20 mesh to 40 mesh.

8. The method according to claim 6, characterized in that The chemical composition of the dry particle glaze includes, by mass percentage, SiO2: 50%~61%, Al2O3: 9.5%~15%, Fe2O3: 0.05%~0.2%, CaO: 6.5%~12%, MgO: 0.85%~1.2%, K2O: 4.5%~6.3%, Na2O: 1.8%~2.2%, P2O5: 0.15%~0.3%, and ZnO: 5.5%~9.5%.

9. The method according to claim 6, characterized in that The dry granular glaze is applied by pouring glaze; the specific gravity of the dry granular glaze is 1.45-1.55 g / cm 3 , glaze application amount is 960~1100g / m 2 .

10. The method according to claim 6, characterized in that The grayscale of the glue pattern is 30% to 40%.

11. The method according to claim 6, characterized in that The firing temperature is 1130-1180° C., and the firing period is 40-45 minutes.

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