Thangka preparation method combined with porcelain painting process

Abstract

The invention relates to the field of combination of a ceramic process and traditional art, and discloses a preparation method of Thangka by combining a porcelain painting process, which comprises the following steps: carrying out surface hydroxylation treatment on a green body, and introducing and activating hydroxyl on the surface of the green body; preparing modified frankincense oil, adding a silane coupling agent and nanoparticles into the frankincense oil, and enhancing the adhesive force and physical stability of the frankincense oil through chemical modification; uniformly coating the modified frankincense oil on the surface of the plain blank, drying and standing to form a stable bonding layer; drawing a line draft on the bonding layer, and smearing the pink or new-color pigment to complete pattern design; the pigment and the bonding layer are cured through multiple times of high-temperature firing, and meanwhile the color of the golden pigment is protected through low-temperature firing; and finally, naturally cooling to obtain the Thangka. The method is simple in process, high in controllability, capable of remarkably improving the art expressive force and long-term storage performance of the Thangka and suitable for industrial production and protection and inheritance of traditional Thangka art.

Description

Technical Field

[0001] The present invention relates to the technical field of the combination of ceramic technology and traditional art, and specifically to a method for preparing Thangka combined with porcelain painting technology. Background Art

[0002] The production of Thangka usually involves complex painting and craftsmanship techniques. However, traditional Thangka mostly uses cloth or paper materials as carriers, and these materials are prone to aging, cracking or fading in long-term preservation and environments with high humidity, high temperature, etc., resulting in damage to the artistic expressiveness and cultural value of the works. To overcome the above problems, porcelain painting technology has gradually been introduced into the production of Thangka, taking advantage of the high hardness and durability of porcelain materials to enable the Thangka patterns to maintain their delicate details and color effects for a long time.

[0003] In the existing Thangka production technology combined with porcelain painting technology, the method of directly applying pigments on the surface of the porcelain embryo and firing is usually adopted. However, due to the smooth surface and lack of activity of the porcelain embryo, it is difficult for the pigments to adhere firmly, and problems such as peeling or uneven color are likely to occur during the firing process. In addition, traditional adhesion layers such as resin or ordinary colloid are prone to decomposition or flow in high-temperature environments, resulting in defects such as distortion or insufficient durability of the fired patterns. At the same time, the interfacial bonding force between the pigment layer and the porcelain embryo is weak, making it difficult to meet the requirements of high-precision and multi-level color expression for complex Thangka patterns.

[0004] Based on this, there are still significant deficiencies in the prior art in terms of the surface treatment of the porcelain embryo, the modification of the adhesion layer, and the improvement of the pattern color expressiveness. There is an urgent need for a technical method that can enhance the adhesion performance of the porcelain embryo surface, improve the binding stability of the pigments, and optimize the color performance to better adapt to the artistic characteristics and long-term preservation requirements of Thangka. In view of the above-mentioned defects of the prior art, the present invention proposes a method for preparing Thangka combined with porcelain painting technology, aiming to improve the overall production quality of Thangka through a series of innovative processes. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a method for preparing Thangka combined with porcelain painting technology, which solves the problems of insufficient adhesion on the surface of the porcelain embryo, poor binding stability of the pigments, and limited color expressiveness in the production process of Thangka combined with porcelain painting technology.

[0006] To achieve the above object, the present invention is realized through the following technical solutions: A method for preparing Thangka combined with porcelain painting technology, comprising the following steps:

[0007] 1) Perform surface hydroxylation treatment on the green body, including soaking the green body in a dilute acid solution to remove surface impurities and introduce hydroxyl groups, and then performing high-temperature heat treatment to activate the hydroxyl groups;

[0008] 2) Prepare the modified frankincense oil, including adding a silane coupling agent and nanoparticles to the frankincense oil, uniformly dispersing them, and then standing for curing;

[0009] 3) Uniformly coat the modified frankincense oil on the surface of the hydroxylated green body, and dry and stand it to form a stable bonding layer;

[0010] 4) Draw a sketch on the surface of the green body coated with frankincense oil, and apply pigments on it to complete the pattern design;

[0011] 5) Fire the pattern, with at least one initial firing and an optional second firing to fix the pattern and colors;

[0012] 6) Naturally cool after firing to obtain the finished Thangka.

[0013] Preferably, the dilute acid solution in the hydroxylation treatment is a 0.5% - 1.5% nitric acid solution or acetic acid solution, and the soaking time is 3 - 5 minutes; the temperature of the high-temperature heat treatment is 400 - 450 °C, and the duration is 2 - 3 hours.

[0014] Preferably, the silane coupling agent added to the frankincense oil is 3% - 5% 3-aminopropyltriethoxysilane, and the nanoparticles are 0.5% - 1% silica or alumina, with a particle size of 10 - 50 nm.

[0015] Preferably, the coating thickness of the modified frankincense oil is 50 - 100 μm, and after coating, it is dried at a low temperature of 50 - 60 °C for 10 - 15 minutes.

[0016] Preferably, the sketch is drawn using black pigment, and the black pigment is iron oxide or copper oxide, and the pigment is uniformly coated on the surface of the frankincense oil bonding layer.

[0017] Preferably, the temperature of the initial firing is 800 °C, and the duration is 6 - 8 hours. The temperature of the second firing is 800 - 850 °C, and the duration is 4 - 6 hours.

[0018] Preferably, in this method, if a gold part needs to be added to the pattern, gold pigment is applied, and a final low-temperature firing is carried out, with a temperature of 600 - 700 °C and a duration of 2 - 3 hours.

[0019] Preferably, the cooling method is natural cooling to room temperature, and the cooling time is 6 - 8 hours.

[0020] The present invention also provides a Thangka combined with porcelain painting technology prepared by the above method.

[0021] The present invention provides a method for preparing a Thangka combined with porcelain painting technology. It has the following beneficial effects:

[0022] 1. The present invention performs hydroxylation treatment on the embryo to remove surface impurities and activate surface hydroxyl groups, so that the embryo has highly active chemical bonding ability. High-temperature heat treatment further enhances the activity of the embryo surface, provides a stable reaction site for the combination of modified frankincense oil and the embryo surface, thereby significantly improving the firmness of the adhesion layer.

[0023] 2. The modification of frankincense oil of the present invention adopts the combined technology of silane coupling agent and nanoparticles, realizes the firm combination of frankincense oil and plain embryo through the introduction of chemical bond, and strengthens the mechanical strength and heat resistance of frankincense oil layer through the filling effect of nanoparticles. This modification effectively solves the problem that traditional frankincense oil coating is easy to decompose or lacks adhesion during high temperature firing.

[0024] 3. The present invention draws a pattern on the modified frankincense oil binding layer, and the pigment can form a good adhesion effect with the frankincense oil, effectively preventing the pigment from flowing or delaminating during the line draft and coloring process. The multiple gradient smearing technology further enhances the layering and color expression of the pattern, and maintains the fullness and uniformity of the color after high-temperature firing.

[0025] 4. The present invention adopts multiple firing processes to gradually solidify the pigment and frankincense oil bonding layer, so that it is not easy to decompose or flow at high temperature. The first firing fixes the pattern, the second firing adjusts the color level, and the last low-temperature firing protects the gold pigment, which ensures the overall stability and detail clarity of the pattern and avoids the distortion or cracks that may be caused by one-time high-temperature firing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings of the present invention specification to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Please see attached Figure 1 The present invention provides a thangka preparation method combined with porcelain painting technology, aiming to improve the adhesion, color expression and durability of thangka patterns by optimizing the surface treatment of porcelain embryos and frankincense oil modification.

[0029] The method for preparing a thangka combined with a porcelain painting process may include the following steps:

[0030] S1, performing surface hydroxylation treatment on the embryo;

[0031] S2, preparing modified frankincense oil;

[0032] S3. Coat the modified frankincense oil on the surface of the blank body.

[0033] S4. Draw a sketch on the surface of the blank body and apply pigments on it to complete the pattern design.

[0034] S5. Fire the pattern.

[0035] S6. After firing, cool it to obtain the finished Thangka.

[0036] The following details the specific implementation manners of each step of the method of the present invention.

[0037] For step S1, in this embodiment, first select a blank body suitable for the process requirements of the present invention. The blank body is an unglazed porcelain body, the surface of which is required to be flat and crack-free, and the thickness range is 3 - 6 mm to ensure the smooth implementation of the subsequent coating and firing steps.

[0038] In this embodiment, in order to improve the surface activity of the blank body and enhance the adhesion between it and the frankincense oil binding layer, surface hydroxylation treatment is performed on the blank body. Specifically, it includes the following operating steps:

[0039] In this embodiment, first immerse the blank body in a dilute acid solution for surface cleaning treatment. The selected dilute acid solution is a 0.5% - 1.5% nitric acid solution or acetic acid solution to remove possible impurities and contaminants on the surface of the blank body, including dust, trace metal ions, and other impurities that are not conducive to the subsequent adhesion of the binding layer.

[0040] In this embodiment, the blank body is immersed in the dilute acid solution for 3 - 5 minutes. During the immersion process, the acid solution chemically corrodes the unstable substances on the surface layer by contacting the surface of the blank body, thereby exposing the active silica groups inside the blank body. At the same time, the concentration and treatment time of the acid solution need to be strictly controlled to avoid damage to the surface structure of the blank body caused by excessive corrosion.

[0041] In this embodiment, after pickling, the blank body is rinsed with distilled water multiple times until the pH value of the surface solution returns to neutral (about pH 7). The function of this step is to thoroughly remove the residual acid solution to avoid its adverse effects on the subsequent frankincense oil coating.

[0042] After completing the above pickling and rinsing, in this embodiment, the blank body is subjected to high-temperature heat treatment. The pickled blank body is placed in a heat treatment furnace and heated at a temperature of 400 - 450 °C for a duration of 2 - 3 hours. Under high-temperature conditions, the activity of the silica groups on the surface of the blank body is further stimulated, and abundant hydroxyl groups (-OH) are formed on the surface, providing necessary reaction sites for the subsequent chemical bonding of frankincense oil.

[0043] In this embodiment, after high-temperature heat treatment, the green body is naturally cooled to room temperature to avoid cracks or surface stress caused by rapid cooling, while maintaining the integrity of surface hydroxyl groups.

[0044] Through the treatment of this step, the surface of the green body has a highly active hydroxylated structure, which can significantly improve the adhesion of the frankincense oil binding layer and lay a foundation for subsequent coating, painting, and firing steps.

[0045] For step S2, in this embodiment, to improve the adhesion performance between the frankincense oil and the surface of the green body and enhance its adhesion ability to pigments, a modification process is used to treat the frankincense oil. The preparation process of the modified frankincense oil includes the introduction of a silane coupling agent and the addition of nanoparticles, so that the frankincense oil has chemical bonding and interface strengthening functions.

[0046] In this embodiment, natural frankincense oil with a purity ≥ 95% is selected, which has good fluidity and high-temperature stability and provides basic adhesion ability for the binding layer.

[0047] In this embodiment, a silane coupling agent is added to the frankincense oil to enhance its chemical bonding force with the surface of the green body. The silane coupling agent is 3-aminopropyltriethoxysilane (KH550), and its addition amount is 3% - 5% of the volume of the frankincense oil. The silane coupling agent is uniformly dispersed in the frankincense oil by stirring, so that its active functional groups can be fully exposed, providing conditions for subsequent chemical reactions.

[0048] During the stirring process, in this embodiment, a magnetic stirrer is used to stir at a speed of 300 - 500 rpm for 10 - 15 minutes to ensure the formation of a preliminary physical bond between the silane coupling agent and the frankincense oil molecules.

[0049] In this embodiment, to further enhance the mechanical properties and high-temperature stability of the frankincense oil, nanoparticles are added to the above mixture. The nanoparticles are silicon dioxide (SiO2) or aluminum oxide (Al2O3), with a particle size range of 10 - 50 nm, and the addition amount is 0.5% - 1% of the volume of the frankincense oil. The introduction of the nanoparticles effectively improves the physical stability of the frankincense oil through filling effects and interface strengthening effects.

[0050] To ensure the uniform dispersion of the nanoparticles in the frankincense oil, in this embodiment, a high-speed disperser is used for treatment, with a dispersion speed of 2000 - 3000 rpm and a dispersion time of 5 - 10 minutes. After the dispersion process is completed, the uniformity of the frankincense oil mixture is checked to ensure that no obvious agglomeration of the nanoparticles occurs.

[0051] In this embodiment, the frankincense oil treated by stirring and dispersion needs to be aged to enable the silane coupling agent to react fully with the frankincense oil to form a stable molecular structure. For this purpose, the prepared frankincense oil is left standing for 10 - 12 hours for aging at room temperature.

[0052] Through the above processing steps, the modified frankincense oil has obtained chemical binding ability and enhanced mechanical properties, enabling it to form a stable binding layer with the surface of the green body, providing guarantee for the adhesion of pigments and the stability of patterns in the subsequent steps.

[0053] For step S3, in this embodiment, to achieve the effective binding of the frankincense oil to the surface of the green body and provide a stable foundation for the subsequent adhesion of pigments, a method of uniformly coating the modified frankincense oil is adopted to form a binding layer. This binding layer can firmly bind to the surface of the green body through chemical and physical actions, and at the same time has good adhesion performance to pigments.

[0054] In this embodiment, the modified frankincense oil used is the frankincense oil prepared in the aforementioned step S2, which has been chemically modified by adding silane coupling agent and nanoparticles, and has high adhesion and enhanced interfacial binding performance. The frankincense oil needs to be fully mixed before use to ensure the uniform distribution of nanoparticles and active ingredients.

[0055] In this embodiment, the modified frankincense oil is coated on the green body that has been surface hydroxylated. The coating method can be manual brushing with a soft brush or coating with a spraying device to ensure that the frankincense oil uniformly covers the surface of the green body. To achieve the best binding effect, the coating thickness is controlled within 50 - 100 μm, which can not only provide sufficient adhesion ability but also avoid delamination or flow during the firing process due to too thick a coating.

[0056] In this embodiment, during the coating process, it is necessary to pay attention to avoiding the generation of bubbles or cracks in the coating. If local non-uniformity occurs, the brushing can be repeated until the surface is flat and defect-free.

[0057] After the coating is completed, in this embodiment, the frankincense oil is dried. To remove the volatile components in the frankincense oil and make it preliminarily cured, the coated green body is placed in an environment of 50 - 60 °C for low-temperature drying for 10 - 15 minutes. During the drying process, it is necessary to avoid excessive flow of the frankincense oil or the failure of chemical components caused by high temperature.

[0058] After the drying treatment is completed, in this embodiment, the green body is left standing for 1 - 2 hours to allow the silane coupling agent in the frankincense oil to fully react with the hydroxyl groups on the surface of the green body to form stable chemical bonds (Si - O - Si bonds). This reaction process is a key step in the formation of the binding layer by coating the frankincense oil, ensuring that the binding layer will not decompose or detach from the surface of the green body during the high-temperature firing process.

[0059] Through the above operations, the frankincense oil binding layer formed in this embodiment has high chemical stability and physical adhesion, providing a reliable foundation for the uniform distribution and adhesion of pigments in the subsequent steps.

[0060] For step S4, in this embodiment, to realize the production of Thangka combined with porcelain painting technology, it is necessary to complete the line drawing and coloring operations on the surface of the blank embryo coated with modified frankincense oil. Through this process, the artistic expression and functional design of the pattern can be realized, and at the same time, it lays a foundation for the subsequent firing step.

[0061] In this embodiment, line drawing is an important step in Thangka production. Its function is to construct the basic framework of the pattern, so that the subsequent coloring operation can strictly follow the requirements of the design draft. In this embodiment, the drawing pigment used is black pigment, and the main components of this pigment are iron oxide or copper oxide, which have high-temperature stability and can maintain the clarity and integrity of the lines during the firing process.

[0062] In this embodiment, when drawing the line drawing, a writing brush or a fine needle tube is used as the drawing tool to achieve fine control of the lines and expression of the complexity of the pattern. During the drawing process, it should be ensured that the black pigment is evenly distributed on the surface of the frankincense oil binding layer to avoid unclear line edges or uneven thickness caused by pigment aggregation. To ensure the drawing quality, it is recommended to carry out the operation in a well-ventilated indoor environment to reduce the influence of external factors on the pigment adhesion.

[0063] In this embodiment, after the line drawing is completed, a coloring operation needs to be carried out on its basis. When coloring, the pigments used are pastel pigments or new color pigments, and these pigments are selected for their excellent color expressiveness and high-temperature firing stability. The coloring process can achieve the transition effect of complex patterns through gradient smearing technology. Especially in the color level design commonly seen in Thangka art, gradient coloring can show the three-dimensional sense and layering of the pattern.

[0064] In this embodiment, when coloring, the operation should be carried out according to the pre-drawn line drawing outline to ensure that the applied pigment completely covers the target area, and at the same time, avoid overstepping the boundary or covering the line drawing. The application of the pigment can be carried out in multiple layers, and each layer of pigment needs to be applied after the previous layer of pigment is dry to ensure the uniformity and layering of the color.

[0065] In this embodiment, during the entire process of line drawing and coloring, special attention should be paid to the adhesion state of the coating. Due to the existence of the frankincense oil binding layer, the pigment can form good adhesion with the surface of the blank embryo, but during the pigment application process, excessive moisture or too thick a pigment layer should be avoided to prevent the pigment from flowing or delaminating during the subsequent firing process.

[0066] Through the above operations, the line drawing and coloring patterns completed in this embodiment can meet the high artistic requirements of Thangka technology, and at the same time have good pigment adhesion and firing stability, providing a reliable basis for the firing process in the subsequent steps.

[0067] For step S5, in this embodiment, in order to fix the completed line drawing and the painted pattern on the surface of the blank and ensure the color stability and durability of the pattern, it is necessary to perform a firing process on the blank coated with pigments. The firing process is a crucial step in the solution of the present invention and directly affects the physical stability and artistic expression effect of the Thangka finished product.

[0068] In this embodiment, the firing process includes at least one primary firing and a secondary firing as required. The primary firing is mainly used to fix the pattern and pigments, so that they form a firm bond with the surface of the blank. The temperature of the primary firing is set at 800 °C, and the holding time is 6 to 8 hours. Within this temperature range, the metal oxides in the pigments chemically combine with the modified frankincense oil binding layer, and at the same time, the components of the modified frankincense oil layer solidify at high temperature, forming a stable interfacial bond with the surface of the blank.

[0069] In this embodiment, the primary firing needs to be carried out in a firing furnace with good temperature uniformity and a controllable heating and cooling rate. Before firing, the painted blank is evenly placed in the firing furnace to avoid local overfiring or incomplete firing caused by improper placement of the blank. The heating rate needs to be controlled at 50 to 100 °C / hour to ensure uniform heating of the blank and avoid surface cracks or coating peeling caused by too fast heating.

[0070] In this embodiment, after the primary firing is completed, a secondary firing can be carried out as needed. The main purpose of the secondary firing is to adjust the details and color levels of the pattern, and further improve the color saturation and expressiveness of the pattern. The temperature of the secondary firing is set at 800 to 850 °C, and the holding time is 4 to 6 hours. During the secondary firing process, the color components in the pigment layer further solidify with the frankincense oil binding layer, and at the same time, the moisture or volatile components that may remain in the high-temperature environment are completely removed, thereby improving the durability and stability of the pattern.

[0071] In this embodiment, if it is necessary to add a golden effect to the pattern, golden pigments can be applied before the secondary firing and a final low-temperature firing is carried out. The temperature of the low-temperature firing is controlled at 600 to 700 °C, and the holding time is 2 to 3 hours. The low-temperature firing can effectively protect the color and adhesion of the golden pigments and avoid oxidation or discoloration of the golden pigments caused by high temperature.

[0072] In this embodiment, after the firing is completed, the blank needs to be naturally cooled to room temperature, and the cooling time is generally 6 to 8 hours. During the cooling process, it is necessary to avoid using rapid cooling methods to prevent the blank from cracking due to excessive thermal stress or damage to the adhesion layer of the surface pattern.

[0073] Through the above steps, the firing process in this embodiment can firmly fix the pigment pattern on the surface of the blank, while ensuring the color uniformity, saturation and overall stability of the pattern, providing an important guarantee for the long-term preservation of the Thangka finished product.

[0074] For step S6, in this embodiment, to ensure that the finished Thangka product meets the required quality requirements, after the firing process is completed, the finished product needs to be naturally cooled and inspected. This step has a direct impact on the final performance, structural integrity, and pattern effect of the finished product.

[0075] In this embodiment, after the firing is completed, the plain embryo with patterns is taken out of the firing furnace and placed in a well-ventilated room-temperature environment for natural cooling. The cooling rate needs to be strictly controlled during the cooling process. Usually, the cooling time is 6 to 8 hours. The purpose of natural cooling is to slowly release the thermal stress introduced by high-temperature firing and avoid phenomena such as cracking, deformation, or peeling of the surface adhesion layer of the plain embryo caused by rapid cooling.

[0076] In this embodiment, during the cooling process, the plain embryo should be avoided being placed in an environment with too high humidity or poor ventilation to prevent local cracks or a decrease in the adhesion of the pigment layer due to the condensation of surface water vapor. There is no need to artificially accelerate the cooling process to ensure the overall stability of the plain embryo.

[0077] In this embodiment, when the finished product has cooled to room temperature, the appearance and structure of the Thangka finished product need to be inspected in detail. First, visually check the integrity of the patterns on the surface of the Thangka to ensure that there are no peeling, bubbles, or over-firing phenomena. At the same time, check whether the boundary between the line drawing and the painted area is clear and whether the pattern colors are uniform.

[0078] In this embodiment, to further confirm the pattern quality and surface adhesion performance, an optical microscope can be used to magnify and observe the surface of the Thangka. Through microscopic observation, the distribution state of pigment particles can be checked to ensure that the pigments have not aggregated or delaminated during the firing process. At the same time, the interface between the essential oil binding layer and the surface of the plain embryo can be observed to judge its binding quality.

[0079] In this embodiment, after the appearance inspection is completed, the color durability of the Thangka finished product also needs to be evaluated. The surface pigments of the finished product sample can be observed for their adhesion and color stability through high-humidity and high-temperature simulated environment tests. This test provides an important basis for the long-term preservation performance of the Thangka finished product.

[0080] Through the above operations, this embodiment has completed the cooling and inspection of the Thangka finished product. The control of the cooling process ensures the stability of the structure of the finished product, and the inspection process ensures the appearance quality, color expressiveness, and long-term durability of the Thangka.

[0081] Generally speaking, the present invention enhances the adhesion performance by performing surface hydroxylation treatment on the green body, introducing and activating surface hydroxyl groups; prepares modified frankincense oil, and uses silane coupling agents and nanoparticles to enhance the chemical bonding ability and physical stability of frankincense oil; uniformly coats the modified frankincense oil on the surface of the green body to form a stable bonding layer; draws a line drawing and colors it on the bonding layer to achieve the artistic expression of the Thangka pattern; fixes the pattern and enhances the durability through multiple high-temperature firings, and finally obtains the finished product after natural cooling and strict inspection.

[0082] To better understand the present invention, the above method will be described in detail below in conjunction with specific embodiments.

[0083] Example 1: Preparation method of Thangka by modifying frankincense oil through traditional process

[0084] In this example, an unglazed porcelain blank with a thickness of 3-6 mm is selected as the substrate. First, the surface of the green body is hydroxylated by soaking the green body in a 0.5% nitric acid solution for 3 minutes to remove surface impurities and introduce hydroxyl groups. After pickling, it is rinsed with distilled water until neutral, and heat-treated at 400 °C for 2 hours to activate the hydroxyl groups.

[0085] Then, modified frankincense oil is prepared. 3% of 3-aminopropyltriethoxysilane (KH550) is added to natural frankincense oil, and a magnetic stirrer is used to stir at 300 rpm for 15 minutes to uniformly disperse the silane. On this basis, 0.5% of nano-silica particles (particle size of 30 nm) are added and dispersed at 2000 rpm for 10 minutes by a high-speed disperser. The modified frankincense oil is allowed to stand for 12 hours to complete ripening.

[0086] The modified frankincense oil is uniformly coated on the surface of the green body, with a coating thickness of 80 μm, and dried at 50 °C for 10 minutes, and then allowed to stand for 1 hour to complete the chemical bonding between the silane and the hydroxyl groups. After coating, a traditional Thangka pattern is drawn on the frankincense oil bonding layer, the line drawing is depicted with iron oxide black material, and pastel pigments are applied on the basis of the line drawing to complete the pattern design.

[0087] Finally, the green body is initially fired at 800 °C for 6 hours to fix the pattern; then, it is fired again according to requirements at a temperature of 820 °C for 4 hours to enhance the color expressiveness and stability of the pattern.

[0088] Example 2: Preparation method of Thangka by optimizing colors through low-temperature firing

[0089] In this example, a green body with a thickness of 4 mm is selected as the substrate. First, the green body is soaked in a 1% acetic acid solution for 5 minutes for pickling to remove surface contaminants and introduce hydroxyl groups. After pickling, it is rinsed with distilled water multiple times until neutral, and heat-treated at 450 °C for 3 hours to further activate the hydroxyl groups.

[0090] When preparing the modified frankincense oil, 5% of KH550 silane coupling agent was added to the frankincense oil and stirred at 500 rpm for 10 minutes. Subsequently, 1% of alumina nanoparticles (particle size 20 nm) were added, and a high-speed disperser was used to stir at 2500 rpm for 5 minutes to ensure uniform distribution of the particles. The aging time of the modified frankincense oil was 10 hours.

[0091] The modified frankincense oil was coated on the surface of the greenware, and the coating thickness was 70 μm, and uniform distribution was achieved by spraying. After coating, it was dried at 60 °C for 15 minutes and left standing for 2 hours to complete the chemical reaction. On the frankincense oil binding layer, a simplified Thangka line drawing was drawn using copper oxide black pigment, and then new color pigments were applied on the basis of the line drawing, and the color transition of the pattern was achieved by multi-level gradient application.

[0092] After the coloring was completed, the greenware was initially fired at 780 °C for 8 hours; subsequently, gold decoration was added and low-temperature firing was carried out at a temperature of 650 °C for 3 hours to protect the color stability of the gold pigment.

[0093] Example 3: Preparation method for optimizing Thangka production by high-strength pigment adhesion

[0094] In this example, a greenware with a thickness of 5 mm was selected for treatment. The greenware was first soaked in a 1.5% nitric acid solution for 4 minutes, rinsed with distilled water to neutral after pickling to remove impurities. Subsequently, it was heat-treated at 420 °C for 2.5 hours to activate the surface hydroxyl groups and form a uniform chemical bonding interface.

[0095] In the preparation of the modified frankincense oil, 4% of KH550 was added to the frankincense oil and stirred at 400 rpm for 15 minutes. Subsequently, 0.8% of nano-silica particles (particle size 10 nm) were added and dispersed at a speed of 3000 rpm for 10 minutes. The standing and aging time of the frankincense oil was 11 hours to ensure sufficient bonding between the silane and the frankincense oil molecules.

[0096] The modified frankincense oil was evenly coated on the surface of the greenware with a soft brush, the coating thickness was 100 μm, and the drying condition was 55 °C for 12 minutes. After drying, it was left standing for 1.5 hours to complete the chemical bonding. A complex Thangka line drawing was drawn on the coating using a fine syringe, and iron oxide black pigment was used as the pigment. Pastel pigments were stacked layer by layer on the basis of the line drawing, and each layer of coloring had to be completely dried before the next layer was operated to ensure uniform color.

[0097] After the coloring was completed, the first firing was carried out at 820 °C for 7 hours to complete the pattern fixation. According to requirements, the second firing was carried out at 850 °C for 5 hours to further enhance the color saturation and adhesion of the pattern.

[0098] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a Thangka combined with porcelain painting technology, characterized in that, It includes the following steps: 1) Perform surface hydroxylation treatment on the green body, including soaking the green body in a dilute acid solution to remove surface impurities and introduce hydroxyl groups, and then performing high-temperature heat treatment to activate the hydroxyl groups; 2) Prepare modified frankincense oil, including adding a silane coupling agent and nanoparticles to the frankincense oil, allowing it to disperse evenly and then standing for curing; 3) Uniformly coat the modified frankincense oil on the surface of the hydroxylated green body, and perform drying and standing to form a stable bonding layer; 4) Draw a sketch on the surface of the green body coated with frankincense oil, and apply pigments thereon to complete the pattern design; 5) Fire the pattern, undergoing at least one primary firing and an optional secondary firing to fix the pattern and color; 6) After firing, naturally cool to obtain the finished Thangka.

2. The method for preparing a Thangka combining porcelain painting process according to claim 1, characterized in that, The dilute acid solution in the hydroxylation treatment is a 0.5% - 1.5% nitric acid solution or acetic acid solution, and the soaking time is 3 - 5 minutes; the temperature of the high-temperature heat treatment is 400 - 450 °C, and the duration is 2 - 3 hours.

3. A method for preparing a Thangka combined with porcelain painting technology according to claim 1, characterized in that, The silane coupling agent added to the frankincense oil is 3% - 5% 3-aminopropyltriethoxysilane, and the nanoparticles are 0.5% - 1% silica or alumina, with a particle size of 10 - 50 nm.

4. A method for preparing a Thangka combined with porcelain painting technology according to claim 1, characterized in that, The coating thickness of the modified frankincense oil is 50 - 100 μm, and after coating, it is dried at a low temperature of 50 - 60 °C for 10 - 15 minutes.

5. A method for preparing a Thangka combined with porcelain painting technique according to claim 1, characterized in that, The sketch is drawn using black pigment, and the black pigment is iron oxide or copper oxide, and the pigment is uniformly coated on the surface of the frankincense oil bonding layer.

6. A method for preparing a Thangka combining porcelain painting techniques according to claim 1, characterized in that, The temperature of the primary firing is 800 °C, and the duration is 6 - 8 hours. The temperature of the secondary firing is 800 - 850 °C, and the duration is 4 - 6 hours.

7. A method for preparing a Thangka combined with porcelain painting technology according to claim 1, characterized in that In the method, if it is necessary to add a golden part to the pattern, apply golden pigment and perform the last low-temperature firing, with a temperature of 600 - 700 °C and a duration of 2 - 3 hours.

8. A method for preparing a Thangka combining porcelain painting technique according to claim 1, characterized in that, The cooling method is natural cooling to room temperature, and the cooling time is 6 - 8 hours.

9. A Thangka combined with porcelain painting technique, characterized in that, The Thangka combined with porcelain painting technology is prepared by the method described in any one of claims 1 - 8.

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