Biodegradable gel and method for removing paint on surfaces of stone cultural relics

Abstract

The invention discloses biodegradable gel and a method for removing paint on the surfaces of stone cultural relics, and relates to the technical field of stone cultural relic protection. The biodegradable gel comprises the following components in percentage by weight: 30-60% of a bio-based main solvent, 10-30% of a bio-based cosolvent, 5-15% of biogel, 1-10% of a thickening stabilizer and the balance of water, the bio-based main solvent is one or more of methyl lactate, ethyl lactate, propyl lactate and butyl lactate, the bio-based cosolvent is one or more of limonene, terpinene, methyltetrahydrofuran and gamma-valerolactone, and the bio-gum is one or more of xanthan gum, guar gum, carrageenan, locust bean gum and sesbania gum. The thickening stabilizer is one or more of bentonite, kaolin, attapulgite and diatomite. The degradable gel has the advantages of favorable swelling property, biodegradability, no toxicity, safety to the environment and operators, no strong acid substance and capability of preventing the surface of the stone cultural relic from being crisp when in use.

Description

Technical Field

[0001] This invention relates to the field of stone cultural relic protection technology, and in particular to a biodegradable gel and method for removing paint from the surface of stone cultural relics. Background Technology

[0002] Stone artifacts, as important carriers of history and culture, are often covered with paint layers due to human decoration, environmental pollution, and other factors. This not only damages the original appearance of the artifacts but also clogs the pores of the rocks and accelerates the weathering of the rock mass.

[0003] Currently, methods for removing paint from stone artifacts include mechanical cleaning, steam cleaning, laser cleaning, and chemical cleaning. Mechanical cleaning is simple to operate, but it easily causes mechanical damage to the artifact surface, leaving scratches or pits and affecting the artifact's integrity. The high temperature of steam cleaning can cause thermal damage to stone artifacts, exacerbating their structural deterioration. Laser cleaning is inefficient for cleaning large areas of thick paint films, and high-energy lasers can easily cause color changes or micro-cracks on the stone artifact surface. While chemical cleaning is more efficient, traditional chemical cleaning agents not only have poor biodegradability but also easily cause the stone artifact surface to crumble.

[0004] Related technologies disclose a laser cleaning method for stone artifacts. While this method can achieve targeted removal, the dry laser action is prone to generating plasma that blocks energy, and the single-pass paint removal efficiency is low, requiring multiple operations. Furthermore, it poses a potential risk of thermal damage to the oxide film on the artifact's surface. Related technologies also disclose an ultrasonic vibration brush cleaning method for stone artifacts. However, this method relies on the synergy of chemical reagents and physical vibration, resulting in insufficient penetration into thick paint layers. Improper control of the vibration frequency can also easily induce micro-cracks in the rock. Therefore, improving existing cleaning methods for stone artifacts is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention discloses a biodegradable gel and method for removing paint from the surface of stone artifacts, in order to solve the technical problems in related technologies where chemical cleaning agents have poor biodegradability and some cleaning agents can cause the surface of stone artifacts to crumble when using chemical methods to remove paint from the surface of stone artifacts.

[0006] To solve the above problems, the present invention adopts the following technical solution: The first aspect of the present invention discloses a biodegradable gel for removing paint from the surface of stone artifacts.

[0007] This invention relates to a biodegradable gel for removing paint from the surface of stone artifacts, comprising the following components by weight percentage: 30-60% bio-based main solvent, 10-30% bio-based co-solvent, 5-15% bio-gel, 1-10% thickening and stabilizing agent, and the balance being water; wherein the bio-based main solvent is one or more of methyl lactate, ethyl lactate, propyl lactate, and butyl lactate; the bio-based co-solvent is one or more of limonene, terpinene, methyltetrahydrofuran, and γ-valerol; the bio-gel is one or more of xanthan gum, guar gum, carrageenan, locust bean gum, and guar gum; and the thickening and stabilizing agent is one or more of bentonite, kaolin, attapulgite, and diatomaceous earth.

[0008] According to an optional embodiment, the biodegradable gel for removing paint from the surface of stone artifacts comprises the following components by weight percentage: 35-60% bio-based primary solvent, 15-30% bio-based co-solvent, 6-15% bio-glue, 2-10% thickening stabilizer, and the balance being water.

[0009] A second aspect of the present invention discloses a method for preparing a biodegradable gel for removing paint from the surface of stone artifacts.

[0010] The preparation method of the biodegradable gel for removing paint from the surface of stone cultural relics according to any one of the technical solutions of this invention includes the following steps: Step 110: Mix the bio-based main solvent and the bio-based co-solvent, and stir until homogeneous to obtain the first mixture; Step 120: Add bio-glue to the first mixture, and obtain the second mixture after the bio-glue has completely dissolved; Step 130: Add thickening and stabilizing agent to the second mixture, stir evenly, and then add deionized water to adjust the viscosity of the system to obtain a biodegradable gel.

[0011] According to an optional embodiment, in step 110, after mixing the bio-based main solvent and the bio-based co-solvent, the mixture is stirred at a stirring speed of 300 r / min for 10 min. And / or, in step 120, bio-gel is added to the first mixture in batches, and after adding bio-gel to the first mixture, it is stirred at a stirring speed of 500 r / min for 20 min. And / or, in step 130, the thickening stabilizer is added to the second mixture in batches, and after adding the thickening stabilizer to the second mixture, the mixture is stirred at a stirring speed of 400 r / min for 15 min.

[0012] A third aspect of the present invention discloses a method for removing paint from the surface of stone artifacts.

[0013] The present invention provides a method for removing paint from the surface of stone artifacts, comprising the following steps: Step 210: Pre-treat the surface of the stone artifact to be cleaned to remove dust and water-soluble dirt from the surface of the stone artifact; Step 220: Apply the biodegradable gel to the paint surface to form a gel layer, and let it stand to allow the paint film to swell and soften. The biodegradable gel is the biodegradable gel for removing paint from the surface of stone cultural relics as described in any of the technical solutions of this invention. Step 230: Wipe the swollen paint film with a soft tool; Step 240: Use laser cleaning to clean the residual paint on the surface of the stone artifact; Step 250: Clean the surface of the stone artifact with deionized water to remove residual gel and paint debris.

[0014] According to an optional implementation, in step 220, the thickness of the gel layer formed by applying the biodegradable gel to the paint surface is 0.5-2 mm.

[0015] According to an optional implementation, in step 220, the settling time is determined based on the paint thickness on the surface of the stone artifact. When the paint thickness is ≤50μm, the settling time is 5-10 min; when the paint thickness is 50-100μm, the settling time is 10-20 min; and when the paint thickness is 100-200μm, the settling time is 20-40 min.

[0016] According to an optional implementation, in step 240, the laser wavelength is 1064nm and the scanning speed is 100-1000mm / s; And / or, in step 240, the residual paint on the surface of the stone artifact is laser-cleaned in different areas, and the energy density and number of laser cleaning cycles are determined based on one or more of the following: the type of residual paint on the surface of the stone artifact, the thickness of the residual paint, the degree of aging of the residual paint, the state of the residual paint, and the roughness of the stone artifact substrate.

[0017] According to one optional implementation, when the residual paint thickness on the surface of the stone artifact is ≤10μm, the energy density during laser cleaning is 0.51 J / cm². 2 The laser cleaning process is performed once; when the residual paint thickness on the stone artifact surface is 10-50 μm, the energy density during laser cleaning is 1.01 J / cm³. 2 The laser cleaning process is repeated 1-2 times. When the residual paint thickness on the stone artifact surface is ≥50μm, the energy density during laser cleaning is 1.52 J / cm³. 2 The laser cleaning process requires 2-3 cycles. Alternatively, when the roughness of the stone artifact substrate is ≤10μm, the energy density during laser cleaning is 0.51 J / cm². 2The laser cleaning process is performed once; when the roughness of the stone artifact substrate is 10-50 μm, the energy density during laser cleaning is 1.01 J / cm². 2 The laser cleaning process involves 1-2 cycles; when the roughness of the stone artifact substrate is ≥50μm, the energy density during laser cleaning is 1.52 J / cm². 2 The laser cleaning process takes 2-3 cycles.

[0018] According to one alternative embodiment, the paint on the surface of the stone artifact is one or more of polyurethane paint, epoxy resin paint, and alkyd resin paint.

[0019] The technical solution adopted in this invention can achieve the following beneficial effects: Firstly, the present invention provides a biodegradable gel for removing paint from the surface of stone artifacts. The main component is a lactic acid ester-based biomaterial, which exhibits good swelling properties, is biodegradable, non-toxic, and safe for the environment and operators. Testing shows that the degradation rate of the biodegradable gel can reach over 85% within 30 days, solving the problem of poor biodegradability of chemical cleaning agents used in related technologies for removing paint from the surface of stone artifacts. Furthermore, the biodegradable gel of the present invention does not contain strong acids and will not dissolve the calcium carbonate in the stone artifact during use, thus preventing the surface of the stone artifact from crumbling.

[0020] Secondly, the method for removing paint from the surface of stone artifacts according to this invention first utilizes a biodegradable gel from any of the technical solutions in this invention to initially remove the paint. The biodegradable gel softens and removes the paint film through interfacial penetration and chemical swelling, thus removing most of the paint. Then, laser technology is used to precisely remove the remaining paint. This method not only improves cleaning efficiency and shortens cleaning time, but also reduces the energy density and number of laser cleaning cycles required, minimizing mechanical and thermal damage to the stone artifacts. Specifically, compared to single laser technology, the removal efficiency of this invention is improved by more than 50%, and for a 200μm thick paint layer, the total cleaning time can be controlled within 2 hours.

[0021] Furthermore, the preferred technical solution of the present invention also has the following beneficial effects: This invention utilizes laser cleaning to remove residual paint from the surface of stone artifacts. By precisely controlling one or more factors—such as the type, thickness, aging, and state of the residual paint, and the roughness of the stone substrate—the energy density and number of laser cleaning cycles can be precisely controlled. This avoids mechanical and thermal damage to the stone artifacts caused by excessively high laser energy density, thus meeting the requirements for artifact preservation. Specifically, after cleaning using this method, the microhardness change rate of the stone artifact surface is ≤5%, and the color difference ΔE is ≤2.0, meeting international artifact preservation standards. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a process flow diagram of the method for removing paint from the surface of stone artifacts as described in this application; Figure 2 These are comparison images of the stone artifact surface before and after cleaning in Embodiment 4 of this application, where a is a schematic diagram before cleaning and b is a schematic diagram after cleaning. Figure 3 These are comparison images of the stone artifact surface before and after cleaning in Embodiment 5 of this application, where a is a schematic diagram before cleaning and b is a schematic diagram after cleaning. Figure 4 These are microscopic comparison images of the stone artifact surface before and after cleaning in Embodiment 6 of this application, where a is a schematic diagram before cleaning and b is a schematic diagram after cleaning. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0026] This application describes a biodegradable gel for removing paint from the surface of stone artifacts, characterized by comprising the following components by weight percentage: 30-60% bio-based main solvent, 10-30% bio-based co-solvent, 5-15% bio-gel, 1-10% thickening and stabilizing agent, and the balance being water. Preferably, the composition is 35-60% bio-based main solvent, 15-30% bio-based co-solvent, 6-15% bio-gel, 2-10% thickening and stabilizing agent, and the balance being water.

[0027] Preferably, the bio-based main solvent is one or more of methyl lactate, ethyl lactate, propyl lactate, and butyl lactate; the bio-based co-solvent is one or more of limonene, terpinene, methyltetrahydrofuran, and γ-valerol; the bio-glue is one or more of xanthan gum, guar gum, carrageenan, locust bean gum, and guar gum; and the thickening and stabilizing agent is one or more of bentonite, kaolin, attapulgite, and diatomaceous earth.

[0028] This application describes a biodegradable gel for removing paint from the surface of stone artifacts. The bio-based primary solvent and bio-based co-solvent penetrate the paint film, disrupting the intermolecular forces and causing it to expand, thus reducing the adhesion between the paint and the stone substrate. The bio-adhesive increases the system viscosity, allowing the bio-based primary solvent and co-solvent to form a gel. A thickening stabilizer maintains the rheological properties and structural integrity of the gel. Specifically, the thickening stabilizer is selected from one or more of bentonite, kaolin, attapulgite, and diatomaceous earth. Inorganic particles can absorb water and expand, increasing the system viscosity and ensuring a uniform, non-flowing gel layer during application, meeting construction requirements. Furthermore, the thickening stabilizer inhibits stratification caused by density differences between the bio-adhesive (e.g., xanthan gum) and the bio-based primary solvent and / or co-solvent, strengthens the gel network rigidity, reduces solvent evaporation, and resists external disturbances during the static penetration phase, preventing collapse. This results in a biodegradable gel with excellent swelling effect on the paint.

[0029] While chemical cleaning methods used in related technologies are highly efficient, the organic solvents in traditional chemical cleaning agents often have poor biodegradability, and some contain strong acids that can dissolve calcium carbonate in stone, leading to surface crumbling. The biodegradable gel of this application comprises a bio-based main solvent, a bio-based co-solvent, a bio-glue, and a thickening and stabilizing agent. Specifically, this application uses lactic acid ester-based bio-based materials as the main component, which has good swelling properties, is biodegradable, non-toxic, and safe for the environment and operators. Testing shows that the degradation rate of the biodegradable gel can reach over 85% within 30 days, solving the problem of poor biodegradability of chemical cleaning agents when removing paint from stone artifacts using chemical methods in related technologies. Furthermore, the biodegradable gel of this application does not contain strong acids and will not dissolve calcium carbonate in stone artifacts during use, thus preventing surface crumbling.

[0030] The biodegradable gel of this application, when used to remove paint from the surface of stone cultural relics, causes no damage to the stone cultural relics, has high cleaning efficiency, leaves little residue, and is easy to operate, providing an environmentally friendly and efficient solution for removing paint contaminants from the surface of stone cultural relics.

[0031] The method for preparing a biodegradable gel for removing paint from the surface of stone artifacts according to any of the technical solutions in this application includes the following steps: Step 110: Mix the bio-based primary solvent and the bio-based co-solvent, and stir until homogeneous to obtain the first mixture. For example, place the bio-based primary solvent in a reaction vessel, turn on the stirrer, set the stirring speed to 300 r / min, slowly add the co-solvent to the reaction vessel, and continue stirring for 10 min until the solution is uniform and transparent.

[0032] Step 120: Add bio-gel to the first mixture. After the bio-gel is completely dissolved, a second mixture is obtained. For example, the sieved bio-gel is added to the first mixture in three batches. After the third addition, the stirring speed is stabilized at 500 rpm, and stirring is carried out for 20 minutes until the bio-gel is completely dissolved. Continuous stirring is necessary during the addition of the bio-gel to prevent clumping.

[0033] Step 130: Add the thickening stabilizer to the second mixture, stir until homogeneous, then add deionized water to adjust the viscosity of the system, obtaining a biodegradable gel. For example, the ground thickening stabilizer is added to the second mixture in two batches. After the second addition, the stirring speed is stabilized at 400 rpm, and stirring is performed for 15 minutes to ensure the thickening stabilizer is fully dispersed. For example, when adding deionized water dropwise, stirring is maintained, and the viscosity is measured every 5 minutes until the viscosity meets the requirement of not dripping during coating. After viscosity adjustment, stirring continues for 10 minutes to homogenize the solution, obtaining a biodegradable gel.

[0034] Furthermore, the preparation method of the biodegradable gel for removing paint from the surface of stone artifacts also includes the following steps: allowing the biodegradable gel to stand for 10 minutes to allow air bubbles to escape naturally; and filtering the defoamed biodegradable gel through a 100-mesh filter cloth to remove impurities and undispersed particles.

[0035] Figure 1 A process flow diagram of the method for removing paint from the surface of stone artifacts according to this application is shown. Figure 1 As shown, the method for removing paint from the surface of stone artifacts according to this application includes the steps of surface pretreatment, biodegradable biogel cleaning, laser cleaning, and post-treatment.

[0036] Preferably, the method for removing paint from the surface of stone artifacts according to this application includes the following steps: Step 210: Pre-treat the surface of the stone artifact to be cleaned to remove dust and water-soluble dirt. For example, use a soft brush to remove dust from the surface of the stone artifact, and then wipe the surface with deionized water to remove water-soluble dirt, exposing the paint film to facilitate full contact between the gel and the paint.

[0037] Step 220: Apply the biodegradable gel to the paint surface to form a gel layer, and allow it to stand to allow the paint film to swell and soften. The biodegradable gel is any of the biodegradable gels described in this application used for removing paint from the surface of stone artifacts. For example, the thickness of the gel layer formed by applying the biodegradable gel to the paint surface is 0.5-2 mm.

[0038] Preferably, the settling time is determined based on the paint thickness on the stone artifact surface. More preferably, when the paint thickness is ≤50μm, the settling time is 5-10 minutes; when the paint thickness is 50-100μm, the settling time is 10-20 minutes; and when the paint thickness is 100-200μm, the settling time is 20-40 minutes. Determining the settling time based on the paint thickness on the stone artifact surface allows the paint film to fully swell and soften. The bio-based solvent in the biodegradable gel penetrates into the paint film, disrupting the intermolecular forces and causing it to expand in volume, thereby reducing the adhesion between the paint and the stone substrate. This step utilizes chemical swelling to reduce mechanical damage to the artifact. For example, for a 100μm thick epoxy resin paint, applying a 2mm thick gel layer and settling for 40 minutes can result in a paint film swelling degree of over 80%.

[0039] Step 230: Wipe the swollen paint film with a soft tool. For example, gently wipe the swollen paint film with a towel or cotton swab. Most of the paint will come off with the gel, achieving rapid removal of large areas of paint.

[0040] Step 240: Use laser cleaning to remove residual paint from the surface of the stone artifact. For example, the laser wavelength is 1064nm and the scanning speed is 100-1000mm / s. The laser energy is absorbed by the residual paint, causing it to vaporize or decompose instantly. The stone substrate absorbs very little of this wavelength of laser light, thus avoiding damage to the artifact.

[0041] Preferably, the residual paint on the surface of the stone artifact is laser-cleaned in different areas, and the energy density and number of laser cleaning cycles are determined based on one or more of the following: the type of residual paint on the surface of the stone artifact, the thickness of the residual paint, the degree of aging of the residual paint, the state of the residual paint, and the roughness of the stone artifact substrate.

[0042] For example, when the residual paint thickness on the surface of a stone artifact is ≤10μm, the energy density during laser cleaning is 0.51 J / cm². 2The laser cleaning process is performed once. When the residual paint thickness on the stone artifact surface is 10-50 μm, the energy density during laser cleaning is 1.01 J / cm³. 2 The laser cleaning process is repeated 1-2 times. When the residual paint thickness on the stone artifact surface is ≥50μm, the energy density during laser cleaning is 1.52 J / cm³. 2 The laser cleaning process involves 2-3 cycles. This application precisely controls the energy density and number of laser cleaning cycles, avoiding mechanical and thermal damage to stone artifacts caused by excessively high laser energy density, thus meeting the requirements for artifact preservation.

[0043] For example, when the roughness of the stone artifact substrate is ≤10μm, the energy density during laser cleaning is 0.51 J / cm². 2 The laser cleaning process is performed once; when the roughness of the stone artifact substrate is 10-50 μm, the energy density during laser cleaning is 1.01 J / cm². 2 The laser cleaning process involves 1-2 cycles; when the roughness of the stone artifact substrate is ≥50μm, the energy density during laser cleaning is 1.52 J / cm². 2 The laser cleaning process takes 2-3 cycles.

[0044] For example, firstly, assess the residual amount of gel after pretreatment (it should be ≤10%). If the residue is patchy or locally dense (such as cracked areas), the number of treatments needs to be increased. Secondly, adjust the treatment based on the roughness grading of the stone artifact substrate; when the roughness is ≤10μm, use 0.51J / cm. 2 Single scan, 1.01 J / cm at 10-50 μm 2 Scan 1-2 times; for roughness ≥ 50 μm, use 1.52 J / cm. 2 Scan 2-3 times. High-roughness surfaces require multiple scans due to the risk of heat accumulation (e.g., in Example 4, the sandstone uneven area was scanned twice). Furthermore, the type and aging degree of the paint must be considered. Dense paint films (such as polyurethane paint) or cracked areas require more than two scans with a spot overlap rate ≥60%. Follow a gradual removal principle during operation: After the initial scan at the preset energy, assess the residue through microscopic observation or color difference detection (ΔE≤2.0). If not removed, perform additional scans (≤3 times), increasing the energy density by ≤0.5 J / cm² during supplementary scans. 2 (For example, the energy in the cracked area increases by 0.3-0.5 J / cm for the second time) 2 Ultimately, a microhardness change rate of ≤5% is set as the safety threshold. Through dynamic optimization, a balance can be struck between removal efficiency and the safety of the cultural relics.

[0045] Step 250: Clean the surface of the stone artifact with deionized water to remove residual gel and paint debris. For example, clean the gel-treated and laser-cleaned areas with deionized water to remove residual gel and paint debris. Finally, dry and protect the cleaned areas to improve the weathering resistance of the stone artifact.

[0046] This application provides a method for removing paint from the surface of stone artifacts, applicable to one or more of polyurethane paint, epoxy resin paint, and alkyd resin paint. This method is also applicable to stone artifacts with different surface conditions, such as sandstone, limestone, and marble. By adjusting the gel composition and laser parameters, it can be adapted to stone surfaces with varying porosity and hardness.

[0047] This application provides a method for removing paint from the surface of stone artifacts. It is easy to operate, requires no complicated equipment, and is suitable for field artifact conservation work. The gel can be applied by spraying or brushing, and a portable pulsed laser can be used, weighing ≤5kg, which is convenient for transportation and on-site operation.

[0048] This application presents a method for removing paint from the surface of stone artifacts. First, the paint is initially removed using a biodegradable gel derived from any of the technical solutions described in this application. The biodegradable gel softens and removes the paint film through interfacial penetration and chemical swelling, effectively removing most of the paint. Then, laser technology is used for precise removal of any remaining paint. This method not only improves cleaning efficiency and shortens cleaning time but also reduces the energy density and number of laser cleaning cycles required, minimizing mechanical and thermal damage to the stone artifacts. Specifically, compared to laser technology alone, this application improves removal efficiency by more than 50%, and for a 200μm thick paint layer, the total cleaning time can be controlled within 2 hours.

[0049] This application employs laser cleaning to remove residual paint from the surface of stone artifacts. Based on one or more factors—the type, thickness, aging, and condition of the residual paint, and the roughness of the stone substrate—the energy density and number of laser cleaning cycles can be precisely controlled. This avoids mechanical and thermal damage to the stone artifacts caused by excessively high laser energy density, thus meeting the requirements for cultural relic preservation. Specifically, after cleaning using this method, the microhardness change rate of the stone artifact surface is ≤5%, and the color difference ΔE is ≤2.0, meeting international cultural relic preservation standards. In other words, when using laser cleaning to remove residual paint from the surface of stone artifacts, this application can adapt to stone artifacts with different paint thicknesses and types, as well as different surface conditions, by adjusting laser parameters such as wavelength, energy density, scanning speed, and number of scans.

[0050] The following describes in detail the biodegradable gel and method for removing paint from the surface of stone cultural relics provided in this application, with reference to Examples 1-6.

[0051] Example 1 This embodiment provides the effects of different main solvents and co-solvents on paint. The main solvents are ethyl lactate and propyl lactate, the co-solvents are terpinene and limonene, the bio-glue is xanthan gum, and the thickening and stabilizing agent is bentonite.

[0052] (1) Biodegradable gel formulation (by weight percentage) Formula A: 50% ethyl lactate, 30% terpinene, 10% xanthan gum, 5% bentonite, 5% deionized water.

[0053] Formula B: 50% propyl lactate, 30% limonene, 10% xanthan gum, 5% bentonite, 5% deionized water.

[0054] Formula C: 60% ethyl lactate and propyl lactate (weight ratio 1:1), 20% limonene, 10% xanthan gum, 5% bentonite, and 5% deionized water.

[0055] Formula D: 60% ethyl lactate; 20% limonene; 10% xanthan gum; 5% bentonite; 5% deionized water.

[0056] (2) Preparation method of biodegradable gel Taking formulation A as an example, ethyl lactate and terpinene are mixed and stirred evenly (stirring speed 300 r / min, time 10 min); xanthan gum is added in three batches, and stirring is continued until completely dissolved (stirring speed 500 r / min, time 20 min); bentonite is added in two batches, and stirring is carried out evenly (stirring speed 400 r / min, time 15 min); finally, deionized water is added, and the gel viscosity is adjusted to a suitable range (it does not flow during coating, and the diffusion diameter of the gel after falling from a height of 5 mm in the drop test is ≤10 mm), thus obtaining a biodegradable gel. The entire preparation process is carried out at room temperature.

[0057] The preparation methods for the remaining formulas are the same as those for formula A, and will not be repeated here.

[0058] (3) Swelling performance test For 100μm thick epoxy resin paint samples, each formulation of gel (1mm thick) was applied, and the swelling of the paint film was observed after standing for 20 minutes. The percentage of the swollen area on the paint film surface to the total area of ​​the paint film was quantified by image analysis, which is the paint film swelling degree.

[0059] Results: Formula D showed the fastest swelling rate, with a film swelling degree of 92%, and noticeable bubbling was observed in the film after 10 minutes; Formula C was the second fastest, with a swelling degree of approximately 88%; Formula A had a swelling degree of approximately 85%; and Formula B was the slowest, with a swelling degree of 82%. This is because the solubility parameters of the ethyl lactate agent for epoxy resin paint are closer to those of the epoxy resin paint, and the co-solubilizing effect of limonene is significant, reducing the surface tension of the solvent and promoting penetration.

[0060] (4) Comparison of cleaning efficiency Various biodegradable gel formulations were combined with laser removal technology. The laser wavelength was 1064 nm, the scanning speed was 300 mm / s, and the energy density was 1.0 J / cm³. 2 A 50μm spot diameter and a 30μm scanning interval were used to remove residual epoxy resin paint. The percentage of the paint film area removed was quantified using image analysis, which is the paint removal rate. Subsequent paint removal rates were determined using the same method.

[0061] Results: Formula D had the shortest total cleaning time of 26 min and a paint removal rate of 99.8%; Formula C had a cleaning time of 28 min and a removal rate of 99.2%; Formula A had a cleaning time of 31 min and a removal rate of 99.2%; and Formula B had a cleaning time of 33 min and a removal rate of 98.5%.

[0062] (5) Comparison of degradation rates According to OECD 301B standard, the degradation of each formulation was measured over 30 days. Formulation A had a degradation rate of 85.3%; Formulation B had a degradation rate of 85.1%; Formulation C had a degradation rate of 86.5%; and Formulation D had the highest degradation rate at 87.2%. All formulations had degradation rates greater than 85%, demonstrating excellent biodegradability.

[0063] Example 2: This embodiment describes a method for removing paint from the surface of stone artifacts. It utilizes the biodegradable gel of formulation D from Example 1 combined with laser technology to remove the paint. The biodegradable gel of formulation D and its preparation method are described in Example 1 and will not be repeated here.

[0064] This embodiment describes a method for removing paint from the surface of stone artifacts, comprising the following steps: Pretreatment: Use a soft brush to remove dust from the surface of the sandstone sample (5cm×5cm×5cm, coated with 20-150μm thick alkyd resin paint), and wipe with deionized water.

[0065] Gel application: For areas with a paint thickness ≤ 50 μm, apply a gel thickness of 1 mm and let stand for 10 min; for areas with a paint thickness of 50-100 μm, apply a gel thickness of 1.5 mm and let stand for 20 min; for areas with a paint thickness of 100-150 μm, apply a gel thickness of 2 mm and let stand for 40 min. During this period, cover the gel surface with plastic wrap to prevent solvent evaporation.

[0066] Gel cleaning: Gently wipe the swollen paint film with a cotton swab, controlling the pressure at 0.05MPa, to remove most of the paint, with paint residue ≤10%.

[0067] Laser Removal: Residual paint was removed using laser removal technology with a wavelength of 1064 nm and a scanning speed of 300 mm / s. The energy density was adjusted based on the thickness of the residual paint on the stone artifact surface: when the residual paint thickness was ≤10 μm, the energy density was 0.51 J / cm². 2 One laser scan was performed; when the residual paint thickness was 10-50 μm, the energy density was 1.01 J / cm². 2 One laser scan was performed; when the residual paint thickness was ≥50μm, the energy density was 1.52J / cm². 2 One laser scan.

[0068] Post-treatment: Wash away residual gel and other impurities with deionized water. Finally, dry and protect the cleaned area to improve the weathering resistance of the stone artifacts.

[0069] The calculation method for the difference between the surface color of the statue after cleaning and the original rock color is the same as that for subsequent embodiments, based on GB / T 11186.3-1989. The microhardness of the stone surface is measured based on ASTM E384. The percentage change in microhardness test value before and after cleaning relative to the initial hardness value is the microhardness change rate (%), and the calculation method for subsequent embodiments is the same.

[0070] In this embodiment, the removal rate of alkyd resin paint reached 99.4%. After cleaning, the color difference between the surface of the statue and the original rock was ΔE=1.4, and the microhardness change of the stone surface was 2.1%, which meets the requirements for cultural relic protection. Microscopic observation showed that the original texture and pore structure of the stone surface were well preserved, and no new cracks were found. EDS analysis showed that the elemental composition of the surface after cleaning was consistent with that before cleaning, and no gel components remained.

[0071] Example 3: Samples of cliff carvings with simulated epoxy resin paint coatings (20-150 μm thick) were prepared. Aging experiments were conducted to induce paint cracking in certain areas, simulating the damage to the cliff carvings caused by aging paint. A combination of biodegradable gel and laser technology was used to remove the paint from the stone artifacts.

[0072] The formulation of the biodegradable gel in this embodiment is (by weight percentage): 60% ethyl lactate, 20% limonene, 10% carrageenan, 5% bentonite, and 5% deionized water.

[0073] The preparation method of the biodegradable gel in this embodiment is as follows: Ethyl lactate and limonene are mixed and stirred evenly (stirring speed 300 r / min, time 10 min); carrageenan is added in three portions, and stirring is continued until completely dissolved (stirring speed 500 r / min, time 20 min); bentonite is added in two portions, and stirring is carried out evenly (stirring speed 400 r / min, time 15 min); finally, deionized water is added, and the gel viscosity is adjusted to a suitable range (it does not flow when coated, and the diffusion diameter of the gel after falling from a height of 5 mm in the drop test is ≤10 mm), thus obtaining the biodegradable gel.

[0074] This embodiment describes a method for removing paint from the surface of stone artifacts, comprising the following steps: Pretreatment: Use a soft brush to remove dust from the sample surface, and then wipe with a deionized water swab to remove water-soluble salts.

[0075] Gel application: For areas with a paint thickness ≤ 50 μm, apply a gel thickness of 1 mm and let stand for 10 min; for areas with a paint thickness of 50-100 μm, apply a gel thickness of 1.5 mm and let stand for 20 min; for areas with a paint thickness of 100-150 μm, apply a gel thickness of 2 mm and let stand for 40 min. During this period, cover the gel surface with plastic wrap to prevent solvent evaporation.

[0076] Gel cleaning: Gently wipe with a cotton swab. For cracked areas, wipe along the direction of the crack. Pressure ≤0.03MPa. This will remove approximately 90% of the paint.

[0077] Laser removal: Treatment is done in sections; first, apply 0.51 J / cm² to the flat areas. 2 One energy density scan was performed, followed by a scan of the uneven area using 1.01 J / cm². 2 The energy density was scanned twice, with a spot overlap rate of 60%.

[0078] Post-treatment: Wash away residual gel and other impurities with deionized water. Finally, dry and protect the cleaned area to improve the weathering resistance of the stone artifacts.

[0079] In this embodiment, the epoxy resin paint removal rate reached 99.3%. After cleaning, the color difference between the statue surface and the original rock color was ΔE=1.5, and the microhardness change of the stone surface was 2.3%, which meets the requirements for cultural relic protection. Microscopic observation showed that the original texture and pore structure of the stone surface were well preserved, and no new cracks were found. EDS analysis showed that the elemental composition of the surface after cleaning was consistent with that before cleaning, and no gel components remained.

[0080] Example 4 Samples of cliff carvings with simulated polyurethane paint coatings were prepared, with paint thicknesses ranging from 20 to 150 μm and exhibiting tight adhesion to the stone. The paint was then removed from the stone artifacts using a combination of biodegradable gel and laser technology.

[0081] The formulation of the biodegradable gel in this embodiment is as follows (by weight percentage): 35% ethyl lactate, 25% propyl lactate, 20% limonene, 10% xanthan gum, 5% kaolin, and 5% deionized water.

[0082] The preparation method of the biodegradable gel in this embodiment is as follows: Ethyl lactate, propyl lactate and limonene are mixed and stirred evenly (stirring speed 300 r / min, time 10 min); xanthan gum is added in three portions, and stirring is continued until completely dissolved (stirring speed 500 r / min, time 20 min); kaolin is added in two portions, and stirring is carried out evenly (stirring speed 400 r / min, time 15 min); finally, deionized water is added, and the gel viscosity is adjusted to a suitable range (it does not flow when coated, and the diffusion diameter of the gel after falling from a height of 5 mm in the drop test is ≤10 mm), thus obtaining the biodegradable gel.

[0083] This embodiment describes a method for removing paint from the surface of stone artifacts, comprising the following steps: Pretreatment: Use a soft brush to remove dust from the sample surface, and then wipe with a deionized water swab to remove water-soluble salts.

[0084] Gel application: For areas with a paint thickness ≤ 50 μm, apply a gel thickness of 1 mm and let stand for 10 min; for areas with a paint thickness of 50-100 μm, apply a gel thickness of 1.5 mm and let stand for 20 min; for areas with a paint thickness of 100-150 μm, apply a gel thickness of 2 mm and let stand for 40 min. During this period, cover the gel surface with plastic wrap to prevent solvent evaporation.

[0085] Gel cleaning: Gently wipe the swollen paint film with a cotton swab, controlling the pressure at 0.05MPa, to remove most of the paint, with paint residue ≤10%.

[0086] Laser removal: Treatment is done in sections; first, apply 1.01 J / cm² to the flat areas. 2 One energy density scan was performed, followed by a scan of the uneven area using 1.52 J / cm². 2 The energy density was scanned twice, with a spot overlap rate of 60%.

[0087] Post-treatment: Wash away residual gel and other impurities with deionized water. Finally, dry and protect the cleaned area to improve the weathering resistance of the stone artifacts.

[0088] Depend on Figure 2As can be seen, after cleaning using the formula and method of this embodiment, there was almost no paint residue in the cleaned area, and the polyurethane paint removal rate reached 99.5%. The color difference between the surface of the statue and the original rock after cleaning was ΔE=1.2, and the microhardness change of the stone surface was 2.7%, which meets the requirements for cultural relic protection. Microscopic observation showed that the original texture and pore structure of the stone surface were well preserved, and no new cracks were found. EDS analysis showed that the surface elemental composition after cleaning was consistent with that before cleaning, and there was no gel component residue.

[0089] Example 5 Samples of cliff carvings with simulated alkyd resin paint applied to their surfaces were prepared, with paint thicknesses ranging from 20 to 150 μm and exhibiting tight adhesion to the stone. The paint was then removed from the stone artifacts using a combination of biodegradable gel and laser technology.

[0090] The biodegradable gel is the biodegradable gel of formulation D in Example 1. Its formulation and preparation method are the same as those in Example 1, and will not be repeated here.

[0091] This embodiment describes a method for removing paint from the surface of stone artifacts, comprising the following steps: Pretreatment: Use a soft brush to remove dust from the sample surface, and then wipe with a deionized water swab to remove water-soluble salts.

[0092] Gel application: For areas with a paint thickness ≤ 50 μm, apply a gel thickness of 1 mm and let stand for 10 min; for areas with a paint thickness of 50-100 μm, apply a gel thickness of 1.5 mm and let stand for 20 min; for areas with a paint thickness of 100-150 μm, apply a gel thickness of 2 mm and let stand for 40 min. During this period, cover the gel surface with plastic wrap to prevent solvent evaporation.

[0093] Gel cleaning: Gently wipe the swollen paint film with a cotton swab, controlling the pressure at 0.05MPa, to remove most of the paint, with paint residue ≤10%.

[0094] Laser removal: wavelength 1064nm, energy density 1.01J / cm² 2 The scanning speed is 300 mm / s, and the scan is performed once.

[0095] Post-treatment: Wash away residual gel and other impurities with deionized water. Finally, dry and protect the cleaned area to improve the weathering resistance of the stone artifacts.

[0096] Depend on Figure 3As can be seen, after cleaning using the formula and method of this embodiment, there was almost no paint residue in the cleaned area, and the alkyd resin paint removal rate reached 99.2%. The color difference between the surface of the statue and the original rock after cleaning was ΔE=1.4, and the microhardness change of the stone surface was 1.6%, which meets the requirements for cultural relic protection. Microscopic observation showed that the original texture and pore structure of the stone surface were well preserved, and no new cracks were found. EDS analysis showed that the surface elemental composition after cleaning was consistent with that before cleaning, and there was no gel component residue.

[0097] Example 6 Samples of cliff carvings with simulated epoxy resin paint applied to their surfaces were prepared. The paint thickness ranged from 20 to 150 μm. The stone showed no obvious weathering, and the paint adhered tightly to the stone. A combination of biodegradable gel and laser technology was used to remove the paint from the stone artifacts.

[0098] The formulation of the biodegradable gel in this embodiment is as follows (by weight percentage): 60% ethyl lactate, 20% terpinene, 10% xanthan gum, 5% bentonite, and 5% deionized water.

[0099] The preparation method of the biodegradable gel in this embodiment is as follows: Ethyl lactate and terpinene are mixed and stirred evenly (stirring speed 300 r / min, time 10 min); xanthan gum is added in three portions, and stirring is continued until completely dissolved (stirring speed 500 r / min, time 20 min); bentonite is added in two portions, and stirring is carried out evenly (stirring speed 400 r / min, time 15 min); finally, deionized water is added, and the gel viscosity is adjusted to a suitable range (it does not flow when coated, and the diffusion diameter of the gel after falling from a height of 5 mm in the drop test is ≤10 mm), thus obtaining the biodegradable gel.

[0100] This embodiment describes a method for removing paint from the surface of stone artifacts, comprising the following steps: Pretreatment: Use a soft brush to remove dust from the sample surface, and then wipe with a deionized water swab to remove water-soluble salts.

[0101] Gel application: For areas with a paint thickness ≤ 50 μm, apply a gel thickness of 1 mm and let stand for 10 min; for areas with a paint thickness of 50-100 μm, apply a gel thickness of 1.5 mm and let stand for 20 min; for areas with a paint thickness of 100-150 μm, apply a gel thickness of 2 mm and let stand for 40 min. During this period, cover the gel surface with plastic wrap to prevent solvent evaporation.

[0102] Gel cleaning: Gently wipe the swollen paint film with a cotton swab, controlling the pressure at 0.05MPa, to remove most of the paint, with paint residue ≤10%.

[0103] Laser removal: wavelength 1064nm, energy density 1.52J / cm² 2The scanning speed is 200 mm / s, and the scan is performed once.

[0104] Post-treatment: Wash away residual gel and other impurities with deionized water. Finally, dry and protect the cleaned area to improve the weathering resistance of the stone artifacts.

[0105] Depend on Figure 4 As can be seen, after cleaning using the formula and method of this embodiment, microscopic observation revealed almost no paint residue in the cleaned area, and the rock mass itself was not significantly damaged. The epoxy resin paint removal rate reached 99.1%. The color difference between the surface of the statue and the original rock after cleaning was ΔE=1.6, and the microhardness change of the stone surface was 2.1%, which meets the requirements for cultural relic protection. Microscopic observation showed that the original texture and pore structure of the stone surface were well preserved, and no new cracks were found. EDS analysis showed that the surface elemental composition after cleaning was consistent with that before cleaning, and no gel components remained.

[0106] The biodegradable gel and "gel-laser combined" cleaning method provided in this application achieve non-destructive, efficient, and environmentally friendly removal of paint from the surface of stone cultural relics through the interfacial penetration and chemical swelling of bio-based solvents combined with the physical operation of laser removal. The gel components are biodegradable and harmless to the environment. The cleaning process is convenient and adaptable to different types of stone cultural relics and paint contamination. This method overcomes the shortcomings of existing technologies and provides a new and effective means for the protection of stone cultural relics, with broad application prospects. Verification through examples shows that the paint removal rate after cleaning is ≥99%, the stone surface damage rate is ≤1%, and the gel biodegradation rate is ≥85%, making it widely applicable to the surface paint cleaning of grottoes, stone carvings, and stone components.

[0107] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0108] Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0109] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A biodegradable gel for removing paint from the surface of stone artifacts, characterized in that, It comprises the following components by weight percentage: 30-60% bio-based main solvent, 10-30% bio-based co-solvent, 5-15% bio-glue, 1-10% thickener and stabilizer, and the balance being water; The bio-based main solvent is one or more of methyl lactate, ethyl lactate, propyl lactate, and butyl lactate; the bio-based co-solvent is one or more of limonene, terpinene, methyltetrahydrofuran, and γ-valerol; the bio-glue is one or more of xanthan gum, guar gum, carrageenan, locust bean gum, and guar gum; and the thickening and stabilizing agent is one or more of bentonite, kaolin, attapulgite, and diatomaceous earth.

2. The biodegradable gel for removing paint from the surface of stone artifacts according to claim 1, characterized in that, It comprises the following components by weight percentage: 35-60% bio-based main solvent, 15-30% bio-based co-solvent, 6-15% bio-glue, 2-10% thickening and stabilizing agent, and the balance being water.

3. A method for preparing a biodegradable gel for removing paint from the surface of stone artifacts as described in claim 1 or 2, characterized in that, Includes the following steps: Step 110: Mix the bio-based main solvent and the bio-based co-solvent, and stir until homogeneous to obtain the first mixture; Step 120: Add bio-glue to the first mixture, and obtain the second mixture after the bio-glue has completely dissolved; Step 130: Add thickening and stabilizing agent to the second mixture, stir evenly, and then add deionized water to adjust the viscosity of the system to obtain a biodegradable gel.

4. The biodegradable gel for removing paint from the surface of stone artifacts according to claim 3, characterized in that, In step 110, the bio-based main solvent and the bio-based co-solvent are mixed and stirred at a stirring speed of 300 r / min for 10 min. And / or, in step 120, bio-gel is added to the first mixture in batches, and after adding bio-gel to the first mixture, it is stirred at a stirring speed of 500 r / min for 20 min. And / or, in step 130, the thickening stabilizer is added to the second mixture in batches, and after adding the thickening stabilizer to the second mixture, the mixture is stirred at a stirring speed of 400 r / min for 15 min.

5. A method for removing paint from the surface of stone artifacts, characterized in that, Includes the following steps: Step 210: Pre-treat the surface of the stone artifact to be cleaned to remove dust and water-soluble dirt from the surface of the stone artifact; Step 220: Apply the biodegradable gel to the paint surface to form a gel layer, and let it stand to allow the paint film to swell and soften. The biodegradable gel is the biodegradable gel for removing paint from the surface of stone cultural relics as described in claim 1 or 2. Step 230: Wipe the swollen paint film with a soft tool; Step 240: Use laser cleaning to clean the residual paint on the surface of the stone artifact; Step 250: Clean the surface of the stone artifact with deionized water to remove residual gel and paint debris.

6. The method for removing paint from the surface of stone artifacts according to claim 5, characterized in that, In step 220, the thickness of the gel layer formed by applying the biodegradable gel to the paint surface is 0.5-2 mm.

7. The method for removing paint from the surface of stone artifacts according to claim 6, characterized in that, In step 220, the settling time is determined based on the paint thickness on the surface of the stone artifact. When the paint thickness is ≤50μm, the settling time is 5-10 min; when the paint thickness is 50-100μm, the settling time is 10-20 min; and when the paint thickness is 100-200μm, the settling time is 20-40 min.

8. The method for removing paint from the surface of stone artifacts according to claim 5, characterized in that, In step 240, the laser wavelength is 1064nm and the scanning speed is 100-1000mm / s; And / or, in step 240, the residual paint on the surface of the stone artifact is laser-cleaned in different areas, and the energy density and number of laser cleaning cycles are determined based on one or more of the following: the type of residual paint on the surface of the stone artifact, the thickness of the residual paint, the degree of aging of the residual paint, the state of the residual paint, and the roughness of the stone artifact substrate.

9. The method for removing paint from the surface of stone artifacts according to claim 8, characterized in that, When the residual paint thickness on the surface of stone artifacts is ≤10μm, the energy density during laser cleaning is 0.51 J / cm². 2 The laser cleaning process is performed once; when the residual paint thickness on the stone artifact surface is 10-50 μm, the energy density during laser cleaning is 1.01 J / cm³. 2 The laser cleaning process is repeated 1-2 times; when the residual paint thickness on the stone artifact surface is ≥50μm, the energy density during laser cleaning is 1.52J / cm³. 2 The laser cleaning process requires 2-3 cycles. Alternatively, when the roughness of the stone artifact substrate is ≤10μm, the energy density during laser cleaning is 0.51 J / cm². 2 The laser cleaning process is performed once; when the roughness of the stone artifact substrate is 10-50 μm, the energy density during laser cleaning is 1.01 J / cm². 2 The laser cleaning process involves 1-2 cycles; when the roughness of the stone artifact substrate is ≥50μm, the energy density during laser cleaning is 1.52J / cm². 2 The laser cleaning process takes 2-3 cycles.

10. The method for removing paint from the surface of stone artifacts according to claim 6, characterized in that, The paint on the surface of stone cultural relics is one or more of polyurethane paint, epoxy resin paint, and alkyd resin paint.

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