Organic-inorganic hybrid precursor-based gypsum cultural relic repair material and preparation method thereof

Abstract

The invention provides an organic-inorganic hybrid precursor-based gypsum cultural relic repair material and a preparation method, and relates to the technical field of gypsum cultural relic repair, the gypsum cultural relic repair material comprises an organic-inorganic phase precursor and an auxiliary agent, the organic-inorganic phase precursor comprises, by mass, 6-12wt% of an acrylic acid-based organic barium monomer, 6-12wt% of an acrylic acid-based organic barium monomer, 6-12wt% of an acrylic acid-based organic barium monomer, 6-12wt% of an acrylic acid-based organic barium monomer, and the balance of water. 4-8 wt% of an acrylic organic calcium monomer and 80-90 wt% of a first solvent; the auxiliaries comprise the following components in percentage by mass: 0.5-2 wt% of a persulfate initiator, 0.3-1 wt% of a polymer dispersant and 97-99.2 wt% of a second solvent. The material can generate an organic-inorganic interpenetrating polymer network repair layer, the repair layer has high compatibility, strong binding force and excellent toughness, and the toughness, binding strength and long-term compatibility of the cultural relic repair layer are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of gypsum cultural relic restoration technology, specifically relating to an organic-inorganic hybrid precursor-based gypsum cultural relic restoration material and its preparation method. Background Technology

[0002] Plaster artifacts are an important part of human historical and cultural heritage, encompassing a wide range of types including sculptures, mural bases, and architectural components, and carrying rich historical, artistic, and scientific research value. However, plaster itself is porous, has poor water resistance, and low mechanical strength. During long-term preservation, it is susceptible to damage from multiple factors such as temperature and humidity fluctuations, air pollution, microbial erosion, and physical impacts, resulting in surface powdering, efflorescence, localized defects, and even overall collapse. Therefore, the scientific and effective restoration and protection of plaster artifacts is one of the important issues in the field of cultural relic preservation.

[0003] Currently, various technical solutions have been developed in the field of plaster artifact restoration, which can be divided into three main categories based on the core characteristics of the restoration materials: One approach is the traditional inorganic material restoration system, which primarily uses lime mortar, gypsum powder, and natural adhesives for filling and repairing. Lime mortar, gypsum powder, and potassium silicate solution are the core restoration materials, achieving the filling and reinforcement of cultural relics through physical filling or simple chemical reactions. However, the restoration layer of this system is extremely brittle, with very poor impact and fatigue resistance, making it prone to cracking and peeling under environmental stress, thus failing to achieve long-term protection.

[0004] Secondly, there is the organic polymer material restoration system, which uses organic polymers such as epoxy resin and polyurethane as restoration agents. These polymers utilize their good toughness and adhesion to penetrate and reinforce cultural relics or fill gaps. While this system solves the brittleness problem of traditional inorganic materials, it is prone to problems such as aging and yellowing of the organic phase, mismatch between the thermal expansion coefficients and the gypsum matrix, and difficulty in reversible removal during long-term use. These issues can easily cause secondary damage to cultural relics, limiting its application in the restoration of high-value cultural relics.

[0005] Thirdly, there is the organic-inorganic hybrid repair system. This type of solution is a transitional technology developed in recent years to balance the compatibility of inorganic materials with the toughness of organic materials. The core of this system is to physically mix organic polymers with inorganic fillers to form a composite repair material. However, in this system, the organic and inorganic phases are physically mixed and combined, but lack molecular-level interactions, which easily leads to stratification and aggregation, resulting in uneven internal structure and unstable mechanical properties of the repair layer. Moreover, the bonding between the mixed material and the gypsum matrix in this system is still mainly based on physical adsorption, making it difficult to penetrate deep into the pores of the gypsum to form an effective anchor, and the repair layer is still prone to separation from the matrix.

[0006] Therefore, developing gypsum materials for the restoration of cultural relics that combine high compatibility, strong bonding, and high toughness has become an urgent problem to be solved. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, this invention provides an organic-inorganic hybrid precursor-based gypsum material for the restoration of cultural relics and its preparation method. The technical problem to be solved by this invention is achieved through the following technical solution: This invention provides an organic-inorganic hybrid precursor-based gypsum artifact restoration material, comprising: an organic-inorganic phase precursor and an additive, wherein the organic-inorganic phase precursor and the additive are mixed to react in the voids of the gypsum artifact to form a restoration layer. The organic-inorganic phase precursor comprises, by mass percentage: 6-12 wt% acrylate-based organobarium monomer, 4-8 wt% methacrylate-based organocalcium monomer, and 80-90 wt% first solvent; The additives, by weight percentage, comprise: 0.5-2 wt% persulfate initiator, 0.3-1 wt% polymer dispersant, and 97-99.2 wt% second solvent.

[0008] In one embodiment of the present invention, the mass ratio of the organic-inorganic phase precursor to the auxiliary agent is 1:1 to 1:2.

[0009] In one embodiment of the present invention, the acrylate-based organobarium monomer includes one or more of barium methacrylate and barium ethylacrylate; The methacrylate-based organic calcium monomer includes one or more of calcium dimethacrylate and calcium methacrylate.

[0010] In one embodiment of the present invention, the persulfate initiator includes one or more of ammonium persulfate, potassium persulfate, and sodium persulfate; The polymer dispersant includes polycarboxylic acid ethers.

[0011] In one embodiment of the present invention, the first solvent comprises a mixed solution of ethanol and water in a volume ratio of 7:3-8:2; The second solvent includes water.

[0012] Another embodiment of the present invention provides a method for preparing an organic-inorganic hybrid precursor-based gypsum cultural relic restoration material as described in the above embodiments, comprising the following steps: Under stirring conditions, acrylate-based organobarium monomer and methacrylate-based organocalcium monomer are sequentially dissolved in a first solvent to form a mixed solution, and the mixed solution is filtered and allowed to stand to obtain an organic-inorganic phase precursor; Under stirring conditions, the polymer dispersant and persulfate initiator are dissolved sequentially in a second solvent and then filtered to obtain the additive.

[0013] In one embodiment of the present invention, filtering and settling the mixed solution includes: The mixed solution was filtered through a filter membrane, and then the filtered solution was placed in a sealed container and allowed to stand at room temperature for 20-30 minutes.

[0014] Another embodiment of the present invention provides the application of the organic-inorganic hybrid precursor-based gypsum artifact restoration material as described in the above embodiments in the restoration of gypsum artifacts, including the following steps: An organic-inorganic phase precursor and an additive are mixed in a preset ratio to obtain a repair solution. The repair solution is then applied to the damaged area of ​​the plaster artifact within a preset time and penetrates into the interior of the plaster artifact to obtain a pre-treated plaster artifact. The pretreated plaster artifacts are subjected to preliminary curing and secondary curing at preset temperature and humidity to obtain the restored plaster artifacts.

[0015] In one embodiment of the present invention, the preset temperature for initial curing is 20-25°C, the preset humidity is 50%-60%, and the curing time is 24-48h.

[0016] In one embodiment of the present invention, the preset temperature for the secondary curing is 20-25°C, the preset humidity is 40%-50%, and the curing time is 3-7 days.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The plaster artifact restoration material of this invention adopts a two-component mixed system of organic-inorganic phase precursor solution and auxiliary agent solution. After the two components are mixed in the pores of the plaster artifact, the organic-inorganic phase precursor first undergoes free radical polymerization of the organic phase under the trigger of the initiator to form a cross-linked network. Then, the microenvironment created by the polymerization process induces in-situ mineralization of the inorganic phase, generating BaSO4 and CaCO3 crystals, and finally forming an organic-inorganic interpenetrating polymer network restoration layer. This results in a strong chemical bond and physical interlocking between the restoration protective layer and the plaster matrix. The cross-linked network provides the restoration layer with excellent toughness, elasticity and adhesion to the plaster matrix, while the in-situ generated nanoscale BaSO4 and CaCO3 crystals provide the restoration layer with sufficient hardness, water resistance and corrosion resistance. This makes the organic-inorganic interpenetrating polymer network restoration layer have high compatibility, strong bonding force and excellent toughness, which greatly improves the toughness, bonding strength and long-term compatibility of the artifact restoration layer, and effectively avoids the problems of easy cracking and peeling of existing protective layers. Attached Figure Description

[0018] Figure 1 A schematic flowchart illustrating a method for preparing an organic-inorganic hybrid precursor-based gypsum cultural relic restoration material according to an embodiment of the present invention; Figure 2A flowchart illustrating the application of an organic-inorganic hybrid precursor-based gypsum cultural relic restoration material in the restoration of gypsum cultural relics, as provided in this embodiment of the invention; Figure 3 This is a SEM image of the repair solution after curing, provided in an embodiment of the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0020] This invention provides an organic-inorganic hybrid precursor-based gypsum artifact restoration material. The material comprises an organic-inorganic phase precursor and additives. The organic-inorganic phase precursor and additives are mixed and react within the voids of the gypsum artifact to form a restoration layer. Specifically, by mass percentage, the organic-inorganic phase precursor comprises: 6-12 wt% acrylic-based organobarium monomer, 4-8 wt% methacrylic-based organocalcium monomer, and 80-90 wt% of a first solvent; the additives by mass percentage comprise: 0.5-2 wt% persulfate initiator, 0.3-1 wt% polymer dispersant, and 97-99.2 wt% of a second solvent.

[0021] Specifically, the mass ratio of organic-inorganic phase precursor to auxiliaries is 1:1 to 1:2.

[0022] Specifically, the methacrylate-based organobarium monomer includes one or more of barium methacrylate and barium ethyl acrylate; the methacrylate-based organocalcium monomer includes one or more of calcium dimethacrylate and calcium methacrylate.

[0023] Specifically, the persulfate initiator includes one or more of ammonium persulfate, potassium persulfate, and sodium persulfate; the polymer dispersant includes polycarboxylic acid ether.

[0024] Specifically, the first solvent consists of a mixture of ethanol and water in a volume ratio of 7:3 to 8:2. The use of ethanol can increase the penetration rate of the solution into the pores of the gypsum. The second solvent consists of water.

[0025] This invention employs a two-component mixed system of organic-inorganic phase precursor and additives. The organic phase polymerization and inorganic phase mineralization reactions are synergistically sequenced through component design. After the organic-inorganic phase precursor and additives are mixed within the pores of gypsum artifacts, the persulfate initiator in the additives triggers free radical polymerization of the acrylate-based organobarium monomer and the acrylate groups in the methacrylate-based organocalcanthenic monomer, gradually forming a cross-linked polyacrylate network. On one hand, during the polymerization process, as the persulfate decomposes and polymerization proceeds, the system experiences a slight acidity shift. This acidic pH environment can reduce the Ba... 2+ Ca 2+The hydrolysis tendency of the persulfate initiator enhances its reactivity with anions, providing thermodynamic conditions for subsequent ion precipitation. Simultaneously, the persulfate initiator generates SO4. 2- SO4 in gypsum 2- It will also dissolve in trace amounts in an acidic pH environment; the acidic environment promotes the dissolution of CO2 to produce CO3. 2- This provides conditions for the formation of inorganic phase crystals; on the other hand, Ba... 2+ Ca 2+ Anchored to the organic framework by covalent bonds, it is uniformly dispersed in the polymethyl methacrylate network during polymerization, while the cross-linked polyacrylate network has a three-dimensional porous structure. 2+ With SO4 2- Ca 2+ With CO3 2- Precipitation reactions occur within the network pores, generating nano-BaSO4 and CaCO3 crystals in situ. As the polymerization reaction proceeds completely, the organic network becomes further cross-linked and denser, firmly locking the nano-crystals within the network structure. This forms an interpenetrating structure where the organic network encapsulates the nano-inorganic crystals, preventing crystal detachment or aggregation at the molecular level.

[0026] Please see Figure 1 , Figure 1 This is a schematic flowchart illustrating a method for preparing an organic-inorganic hybrid precursor-based gypsum cultural relic restoration material according to an embodiment of the present invention. The preparation method includes the following steps: Step 1: Under stirring conditions, the acrylic-based organobarium monomer and the methacrylic-based organocalcium monomer are sequentially dissolved in the first solvent to form a mixed solution. The mixed solution is then filtered and allowed to stand to obtain an organic-inorganic phase precursor.

[0027] Specifically, first, the following steps are taken: 1) Measure out the acrylate-based organobarium monomer, the methacrylate-based organocalcium monomer, ethanol, and deionized water according to their mass percentages. 2) Pour the ethanol and deionized water into a flask and stir until homogeneous to form the first solvent. 3) While stirring at 300-500 rpm, slowly add the acrylate-based organobarium monomer to the first solvent. After addition, continue stirring for 15-20 minutes until the solution is free of obvious particles. 4) Add the methacrylate-based organocalcium monomer at the same rate and continue stirring for 15-20 minutes to obtain a homogeneous organometallic monomer solution. 5) Filter the prepared solution through a filter membrane. 6) Place the filtered solution in a sealed container and let it stand at room temperature for 20-30 minutes to remove dissolved air bubbles, obtaining an organic-inorganic phase precursor solution.

[0028] Step 2: Under stirring conditions, the polymer dispersant and persulfate initiator are dissolved sequentially in a second solvent and filtered to obtain the additive.

[0029] Specifically, first, measure out the polymer dispersant, persulfate initiator, and deionized water according to their mass percentages. Then, while stirring at 200-300 rpm, slowly add the polymer dispersant to the deionized water. After adding, stir for 10-15 minutes until the polymer dispersant is completely dissolved and the solution is transparent. Next, while stirring at 200-300 rpm, add the persulfate initiator to the solution in 3-4 portions, with an interval of 3-5 minutes between each addition to avoid excessively high local concentrations that could lead to decomposition. After all the ingredients have been added, continue stirring for 10-15 minutes to ensure the persulfate initiator is completely dissolved, resulting in a homogeneous and transparent additive solution.

[0030] Please see Figure 2 , Figure 2 A flowchart illustrating the application of an organic-inorganic hybrid precursor-based gypsum cultural relic restoration material in the restoration of gypsum cultural relics, as provided in this embodiment of the invention, specifically includes the following steps: Step 1: Mix the organic-inorganic phase precursor and the additives in a preset ratio to obtain a repair solution. Apply the repair solution to the damaged area of ​​the plaster artifact within a preset time and allow it to penetrate into the interior of the plaster artifact to obtain a pre-treated plaster artifact.

[0031] Specifically, first, remove surface dust and stubborn stains from plaster artifacts.

[0032] Then, mix the organic-inorganic phase precursor and the auxiliary agent at a mass ratio of 1:1 to 1:2, pour the mixture into a clean container and stir at a speed of 60-80 rpm for 30-60 seconds to ensure that the two components are fully mixed and homogeneous, thus obtaining a repair solution. The applicable period of the repair solution is 30-60 minutes (at room temperature). It must be applied within the applicable period to avoid premature solidification.

[0033] Next, different repair methods are selected based on the degree of damage to the plaster artifacts, ensuring that the repair solution fully covers the damaged area without causing solution runoff or secondary damage to the artifact due to excessive application. For example, for slightly efflorescent plaster artifacts, a spray method is used to apply the repair solution in small amounts multiple times to the surface, with each spray distance of 15-20 cm and an interval of 15-20 minutes between sprays. This ensures that each spray of solution fully penetrates the powdery layer, preventing rapid surface solidification and the formation of a barrier layer. For artifacts with moderate porosity, an injection method is used to slowly inject the repair solution into the pores in multiple applications, with each injection spaced 20-30 minutes apart, for a total of 2-3 applications, until the pores no longer absorb the solution. For severely damaged plaster artifacts, a combination of layered application and grouting is used. First, the mixed solution is mixed with a small amount of plaster powder at a mass ratio of 10:1 to form a paste. The paste is then gently applied to the damaged area with a scraper, with the thickness controlled to 1-2 mm. After standing for 10-15 minutes, the pure mixed solution is injected into the pores around the damaged area using a low-pressure grouting method to replenish penetration. The application-grouting steps are repeated 2-3 times until the damaged area is flush with the surrounding substrate.

[0034] Step 2: The pre-treated plaster artifacts are initially cured and then cured again under preset temperature and humidity to obtain the restored plaster artifacts.

[0035] Specifically, firstly, under preset temperatures of 20-25℃ and preset humidity of 50%-60%, the treated plaster artifacts are initially cured for 24-48 hours to complete the free radical polymerization reaction of the organic phase. Then, after initial curing, under preset temperatures of 20-25℃ and preset humidity of 40%-50%, curing continues for 3-5 days to ensure complete cross-linking of the organic polymer network and sufficient growth of inorganic crystals. During this period, the surface condition of the repair layer is observed daily; if problems such as whitening or cracking occur, the humidity needs to be adjusted promptly.

[0036] Furthermore, after secondary curing, the surface of the plaster artifact can be polished and repaired to make it consistent with the original surface of the artifact in terms of flatness.

[0037] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that the embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0038] Example 1 An organic-inorganic hybrid precursor-based gypsum material for cultural relic restoration comprises an organic-inorganic phase precursor and additives in a mass ratio of 1:1.5. The organic-inorganic phase precursor consists of 8 wt% barium methacrylate, 6 wt% calcium methacrylate, and 86 wt% a mixed solution of ethanol and deionized water; wherein the volume ratio of ethanol to water is 7:3. The additives consist of 1.0 wt% ammonium persulfate, 0.5 wt% polycarboxylate ether, and 98.5 wt% deionized water.

[0039] The preparation method of the above-mentioned organic-inorganic hybrid precursor-based gypsum cultural relic restoration material includes the following steps: Step 1: Prepare an organic-inorganic phase precursor solution.

[0040] First, weigh out the raw materials barium methacrylate, calcium methacrylate, ethanol, and deionized water according to the above mass percentages; then pour the ethanol and deionized water into a three-necked flask, turn on the stirring device, stir at 300 rpm, and stir for 2 minutes to obtain the first solvent.

[0041] Then, while maintaining a constant stirring speed of 300 rpm, barium methacrylate was slowly added to the first solvent. After the addition was complete, stirring was continued for 15 minutes until there were no obvious particles in the solution. Then, calcium methacrylate was added at the same rate, and stirring was continued for 15 minutes to obtain a homogeneous organometallic monomer solution.

[0042] Next, the above organometallic monomer solution was vacuum filtered using an organic filter membrane to remove trace amounts of insoluble impurities. The filtered solution was placed in a sealed brown reagent bottle and allowed to stand at room temperature (25°C) for 20 minutes to remove dissolved air bubbles, finally yielding an organic-inorganic phase precursor solution.

[0043] Step 2: Prepare the auxiliary agent solution.

[0044] First, weigh out the polycarboxylate ether dispersant, ammonium persulfate, and deionized water according to the above mass percentages; then pour the deionized water into a beaker.

[0045] Then, the polycarboxylate ether dispersant was slowly added to deionized water at a stirring speed of 250 rpm. After the addition was completed, stirring was continued for 10 minutes until the polycarboxylate ether was completely dissolved.

[0046] Finally, while maintaining a constant stirring speed, add ammonium persulfate to the above transparent solution in three portions, with a 5-minute interval between each addition; after all the ammonium persulfate has been added, continue stirring for 15 minutes to ensure complete dissolution, thus obtaining the auxiliary agent solution.

[0047] Step 3, preparation of the repair solution.

[0048] Specifically, the prepared organic-inorganic phase precursor and auxiliary agent are mixed and poured into a clean container for stirring at a speed of 60-80 rpm for 30-60 seconds to ensure that the two components are fully mixed and homogeneous, thus obtaining a repair solution.

[0049] Step 4: Repair the plaster specimen.

[0050] First, the raw materials were weighed and mixed evenly according to the mass ratio of gypsum powder to deionized water of 1:1 to form a mixture. The mixture was poured into a steel mold with internal dimensions of 5×5×2 cm, vibrated to remove air, and allowed to stand for 24 hours before demolding and natural drying to constant weight. The gypsum specimen was then immersed in a 5wt% Na₂SO₄ solution for 24 hours, removed, and allowed to air dry. This process was repeated three times to form a powdery layer on the surface of the specimen, resulting in a slightly brittle gypsum specimen. Afterward, the powdery layer was removed from the surface of the simulated specimen with a soft brush, the surface was wiped with anhydrous ethanol, and allowed to air dry.

[0051] Then, the repair solution prepared in step 3 is applied to the surface of the plaster specimen in small amounts and multiple times using a brushing method. The capillary action of the plaster pores is used to allow the repair solution to fully penetrate until the pores of the plaster specimen no longer absorb the solution.

[0052] Finally, the treated gypsum specimens were placed in a constant temperature and humidity chamber for initial curing, with the temperature set at 23℃ and humidity at 55% for 48 hours to complete the free radical polymerization reaction of the organic phase. After initial curing, the parameters of the constant temperature and humidity chamber were adjusted, setting the temperature at 23℃ and humidity at 45%, and curing continued for 5 days to ensure complete cross-linking of the organic polymer network and sufficient growth of inorganic crystals. During this period, the surface condition of the repair layer was observed daily, and no abnormalities such as whitening or cracking were observed. Simultaneously, the repair solution prepared in step 3 was used to perform initial and secondary curing on the gypsum specimens under the same conditions.

[0053] After the second curing is completed, gently sand the surface of the plaster with fine sandpaper to make it as smooth as the original surface of the specimen, thus completing the repair.

[0054] Please see Figure 3 , Figure 3 This is a SEM image of the repair solution after curing according to an embodiment of the present invention. As can be seen from the image, the repair layer forms an interpenetrating structure of organic network encapsulating nano-inorganic crystals. Nano-BaSO4 and CaCO3 crystals are uniformly dispersed in the polymethacrylate network without obvious agglomeration, and the crystal particle size is 50-200 nm.

[0055] Example 2 An organic-inorganic hybrid precursor-based gypsum material for cultural relic restoration comprises an organic-inorganic phase precursor and additives in a mass ratio of 1:2. The organic-inorganic phase precursor consists of 10 wt% barium ethyl acrylate, 5 wt% calcium dimethacrylate, and 85 wt% a mixed solution of ethanol and deionized water; wherein the volume ratio of ethanol to water is 7:3. The additives consist of 1.5 wt% ammonium persulfate, 0.8 wt% polycarboxylate ether, and 97.7 wt% deionized water.

[0056] The preparation method of the above-mentioned organic-inorganic hybrid precursor-based gypsum cultural relic restoration material includes the following steps: Step 1: Prepare an organic-inorganic phase precursor solution.

[0057] First, weigh out the raw materials barium ethyl acrylate, calcium dimethacrylate, ethanol, and deionized water according to the above mass percentages; then pour the ethanol and deionized water into a three-necked flask, turn on the stirring device, stir at 300 rpm, and stir for 2 minutes to obtain the first solvent.

[0058] Then, while maintaining a constant stirring speed of 300 rpm, slowly add barium ethyl acrylate to the first solvent. After the addition is complete, continue stirring for 15 minutes until there are no obvious particles in the solution. Then, add calcium dimethacrylate at the same addition rate and continue stirring for 15 minutes to obtain a homogeneous organometallic monomer solution.

[0059] Next, the above organometallic monomer solution was vacuum filtered using an organic filter membrane to remove trace amounts of insoluble impurities. The filtered solution was placed in a sealed brown reagent bottle and allowed to stand at room temperature (25°C) for 20 minutes to remove dissolved air bubbles, finally yielding an organic-inorganic phase precursor solution.

[0060] Step 2: Prepare the auxiliary agent solution.

[0061] First, weigh out the polycarboxylate ether dispersant, ammonium persulfate, and deionized water according to the above mass percentages; then pour the deionized water into a beaker.

[0062] Then, the polycarboxylate ether dispersant was slowly added to deionized water at a stirring speed of 250 rpm. After the addition was completed, stirring was continued for 10 minutes until the polycarboxylate ether was completely dissolved.

[0063] Finally, while maintaining a constant stirring speed, add ammonium persulfate to the above transparent solution in three portions, with a 5-minute interval between each addition; after all the ammonium persulfate has been added, continue stirring for 15 minutes to ensure complete dissolution, thus obtaining the auxiliary agent solution.

[0064] Step 3, preparation of the repair solution.

[0065] Specifically, the prepared organic-inorganic phase precursor and auxiliary agent are mixed and poured into a clean container for stirring at a speed of 60-80 rpm for 30-60 seconds to ensure that the two components are fully mixed and homogeneous, thus obtaining a repair solution.

[0066] Step 4: Repair the plaster specimen.

[0067] First, the raw materials were weighed and mixed evenly according to the mass ratio of gypsum powder:deionized water:ammonium bicarbonate = 1:1 to form a mixture. The mixture was poured into a steel mold with internal dimensions of 5×5×2 cm, vibrated to remove air, and allowed to stand for 24 hours before demolding. After demolding, the specimen was placed in a 60℃ oven for 12 hours to dry, allowing the ammonium bicarbonate to decompose and produce CO2 and NH3, forming interconnected pores. Then, it was allowed to cool naturally to room temperature, and residual powder in the pores was removed to obtain a gypsum specimen with moderate porosity.

[0068] Then, the repair solution was slowly injected into the pores in multiple injections, with an interval of 20 minutes between each injection, for a total of 3 injections, until the pores no longer absorbed the solution.

[0069] Finally, the treated plaster specimens were placed in a constant temperature and humidity chamber for initial curing. The temperature was set at 23℃ and the humidity at 55%, with a curing time of 48 hours, to complete the free radical polymerization reaction of the organic phase. After initial curing, the parameters of the constant temperature and humidity chamber were adjusted, setting the temperature to 23℃ and the humidity at 45%, and curing continued for 5 days to ensure complete cross-linking of the organic polymer network and sufficient growth of inorganic crystals. During this period, the surface condition of the repair layer was observed regularly every day, and no abnormalities such as whitening or cracking were observed. After secondary curing, the plaster surface was gently sanded with fine sandpaper to make it consistent with the original surface of the specimen, completing the repair.

[0070] Example 3 An organic-inorganic hybrid precursor-based gypsum material for cultural relic restoration comprises an organic-inorganic phase precursor and additives in a 1:1 mass ratio. The organic-inorganic phase precursor consists of 12 wt% barium methacrylate, 7 wt% calcium dimethacrylate, and 81 wt% a mixed solution of ethanol and deionized water, wherein the volume ratio of ethanol to water is 8:2. The additives consist of 2 wt% sodium persulfate, 0.8 wt% polycarboxylate ether, and 97.2 wt% deionized water.

[0071] The preparation method of the above-mentioned organic-inorganic hybrid precursor-based gypsum cultural relic restoration material includes the following steps: Step 1: Prepare an organic-inorganic phase precursor solution.

[0072] First, weigh out the raw materials barium methacrylate, calcium dimethacrylate, ethanol, and deionized water according to the above mass percentages; then pour the ethanol and deionized water into a three-necked flask, turn on the stirring device, stir at 300 rpm, and stir for 2 minutes to obtain the first solvent.

[0073] Then, while maintaining a constant stirring speed of 300 rpm, barium methacrylate was slowly added to the first solvent. After the addition was complete, stirring was continued for 15 minutes until no obvious particles were present in the solution. Then, calcium dimethacrylate was added at the same rate, and stirring was continued for 15 minutes to obtain a homogeneous organometallic monomer solution.

[0074] Next, the above organometallic monomer solution was vacuum filtered using an organic filter membrane to remove trace amounts of insoluble impurities. The filtered solution was placed in a sealed brown reagent bottle and allowed to stand at room temperature (25°C) for 20 minutes to remove dissolved air bubbles, finally yielding an organic-inorganic phase precursor solution.

[0075] Step 2: Prepare the auxiliary agent solution.

[0076] First, weigh out the polycarboxylate dispersant, sodium persulfate, and deionized water according to the above mass percentages; then pour the deionized water into a beaker.

[0077] Then, the polycarboxylate ether dispersant was slowly added to deionized water at a stirring speed of 250 rpm. After the addition was completed, stirring was continued for 10 minutes until the polycarboxylate ether was completely dissolved.

[0078] Finally, while maintaining a constant stirring speed, add sodium persulfate to the above transparent solution in three portions, with a 5-minute interval between each addition; after all the sodium persulfate has been added, continue stirring for 15 minutes to ensure complete dissolution, thus obtaining the auxiliary agent solution.

[0079] Step 3, preparation of the repair solution.

[0080] Specifically, the prepared organic-inorganic phase precursor and auxiliary agent are mixed and poured into a clean container for stirring at a speed of 60-80 rpm for 30-60 seconds to ensure that the two components are fully mixed and homogeneous, thus obtaining a repair solution.

[0081] Step 4: Repair the plaster specimen.

[0082] First, the raw materials were weighed and mixed evenly according to the mass ratio of gypsum powder to deionized water of 1:1 to form a mixture. The mixture was poured into a steel mold with internal dimensions of 5×5×2 cm, vibrated to remove air, and left to stand for 24 hours before demolding and allowing it to dry naturally to a constant weight. Then, a 1×1×0.5 mm defect area was cut out from the gypsum specimen, and the edges of the defect were sanded to an irregular shape to obtain a severely defective gypsum specimen.

[0083] Then, mix the repair solution from step 3 with plaster powder at a mass ratio of 10:1 to make a paste-like repair agent. Apply the paste-like repair agent to the damaged area and let it stand for 10-20 minutes. Then, inject the repair solution into the pores around the damaged area and let it stand for about 10 minutes. Repeat this process 2-3 times.

[0084] Finally, the treated plaster specimens were placed in a constant temperature and humidity chamber for initial curing. The temperature was set at 23℃ and the humidity at 55%, with a curing time of 48 hours, to complete the free radical polymerization reaction of the organic phase. After initial curing, the parameters of the constant temperature and humidity chamber were adjusted, setting the temperature to 23℃ and the humidity at 45%, and curing continued for 5 days to ensure complete cross-linking of the organic polymer network and sufficient growth of inorganic crystals. During this period, the surface condition of the repair layer was observed regularly every day, and no abnormalities such as whitening or cracking were observed. After secondary curing, the plaster surface was gently sanded with fine sandpaper to make it consistent with the original surface of the specimen, completing the repair.

[0085] The plaster specimens from Examples 1, 2, and 3, before and after repair, were tested for compressive strength, tensile properties (interfacial bond strength), flexibility (maximum bending deformation), water resistance, and corrosion resistance. The water resistance test conditions were: the samples were immersed in deionized water for 72 hours, and the water absorption rate and surface condition were measured. The corrosion resistance test conditions were: the samples were immersed in 5wt% Na₂SO₄ solution for 30 days, and the strength retention rate was measured. The test results are shown in Table 1.

[0086] Table 1

[0087] As can be seen from the test results above, the specimens repaired in Examples 1, 2, and 3 are significantly better than the unrepaired specimens in terms of compressive strength, interfacial bonding strength, flexibility, water resistance, and corrosion resistance, demonstrating the high-efficiency repair capability of the repair material of the present invention.

[0088] In summary, the gypsum cultural relic restoration material of this invention adopts a two-component mixed system of organic-inorganic phase precursor solution and auxiliary agent solution. After the two components are mixed in the pores of the gypsum cultural relic, the organic-inorganic phase precursor first undergoes free radical polymerization of the organic phase under the trigger of the initiator to form a cross-linked network. Then, the microenvironment created by the polymerization process induces in-situ mineralization of the inorganic phase, generating BaSO4 and CaCO3 crystals, and finally forming an organic-inorganic interpenetrating polymer network restoration layer. This results in a strong chemical bond and physical interlocking between the restoration protective layer and the gypsum matrix. The cross-linked network provides the restoration layer with excellent toughness, elasticity and adhesion to the gypsum matrix, while the in-situ generated nanoscale BaSO4 and CaCO3 crystals provide the restoration layer with sufficient hardness, water resistance and corrosion resistance. This makes the organic-inorganic interpenetrating polymer network restoration layer have high compatibility, strong bonding force and excellent toughness, which greatly improves the toughness, bonding strength and long-term compatibility of the cultural relic restoration layer, and effectively avoids the problems of easy cracking and peeling of existing inorganic protective layers.

[0089] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. An organic-inorganic hybrid precursor-based gypsum material for the restoration of cultural relics, characterized in that, include: An organic-inorganic phase precursor and an additive are used, wherein the organic-inorganic phase precursor and the additive are mixed to react in the pores of plaster artifacts to form a repair layer. The organic-inorganic phase precursor comprises, by mass percentage: 6-12 wt% acrylate-based organobarium monomer, 4-8 wt% methacrylate-based organocalcium monomer, and 80-90 wt% first solvent; The additives, by weight percentage, comprise: 0.5-2 wt% persulfate initiator, 0.3-1 wt% polymer dispersant, and 97-99.2 wt% second solvent.

2. The organic-inorganic hybrid precursor-based gypsum cultural relic restoration material according to claim 1, characterized in that, The mass ratio of the organic-inorganic phase precursor to the auxiliary agent is 1:1 to 1:

2.

3. The organic-inorganic hybrid precursor-based gypsum cultural relic restoration material according to claim 1, characterized in that, The acrylate-based organobarium monomer includes one or more of barium methacrylate and barium ethyl acrylate. The methacrylate-based organic calcium monomer includes one or more of calcium dimethacrylate and calcium methacrylate.

4. The organic-inorganic hybrid precursor-based gypsum cultural relic restoration material according to claim 1, characterized in that, The persulfate initiator includes one or more of ammonium persulfate, potassium persulfate, and sodium persulfate; The polymer dispersant includes polycarboxylic acid ethers.

5. The organic-inorganic hybrid precursor-based gypsum cultural relic restoration material according to claim 1, characterized in that, The first solvent comprises a mixed solution of ethanol and water in a volume ratio of 7:3 to 8:2; The second solvent includes water.

6. A method for preparing an organic-inorganic hybrid precursor-based gypsum cultural relic restoration material as described in any one of claims 1-5, characterized in that, Including the following steps: Under stirring conditions, acrylate-based organobarium monomer and methacrylate-based organocalcium monomer are sequentially dissolved in a first solvent to form a mixed solution, and the mixed solution is filtered and allowed to stand to obtain an organic-inorganic phase precursor; Under stirring conditions, the polymer dispersant and persulfate initiator are dissolved sequentially in a second solvent and then filtered to obtain the additive.

7. The preparation method of the organic-inorganic hybrid precursor-based gypsum cultural relic restoration material according to claim 6, characterized in that, The mixture is filtered and allowed to stand, including: The mixed solution was filtered through a filter membrane, and then the filtered solution was placed in a sealed container and allowed to stand at room temperature for 20-30 minutes.

8. The application of an organic-inorganic hybrid precursor-based gypsum cultural relic restoration material as described in any one of claims 1-5 in the restoration of gypsum cultural relics, characterized in that, Including the following steps: An organic-inorganic phase precursor and an additive are mixed in a preset ratio to obtain a repair solution. The repair solution is then applied to the damaged area of ​​the plaster artifact within a preset time and penetrates into the interior of the plaster artifact to obtain a pre-treated plaster artifact. The pretreated plaster artifacts are subjected to preliminary curing and secondary curing at preset temperature and humidity to obtain the restored plaster artifacts.

9. The application of the organic-inorganic hybrid precursor-based gypsum cultural relic restoration material according to claim 8 in the restoration of gypsum cultural relics, characterized in that, The preset temperature for initial curing is 20-25℃, the preset humidity is 50%-60%, and the curing time is 24-48h.

10. The application of the organic-inorganic hybrid precursor-based gypsum cultural relic restoration material according to claim 8 in the restoration of gypsum cultural relics, characterized in that, The preset temperature for the secondary curing is 20-25℃, the preset humidity is 40%-50%, and the curing time is 3-7 days.

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