Stone cultural relic surface paint cleaning method and application thereof

Abstract

The invention discloses a stone cultural relic surface paint cleaning method and application thereof, and relates to the technical field of stone cultural relic protection. The method comprises the steps that floating dust on the surface of the stone cultural relic is removed through a banister brush, then the surface of the stone cultural relic is wiped with deionized water, water-soluble dirt is removed, and a complete paint film is exposed; sand blasting equipment is adopted for conducting sand blasting treatment on the paint surface, and the sand blasting pressure ranges from 0.1 MPa to 0.3 MPa; the cleaning agent is evenly smeared on the surface of the residual paint after sand blasting, after standing, the residual paint film is swelled and softened, and the cleaning agent is prepared from, by weight, 5%-20% of phospholipid biosurfactant, 10%-30% of bio-based cosolvent, 1%-8% of thickening stabilizer and the balance deionized water; the swelled residual paint is removed through pulse laser equipment; and washing the cleaning area with deionized water, removing the residual cleaning agent and paint chippings, and performing protection treatment on the surface of the stone cultural relic after natural drying. The method is an efficient, lossless and environment-friendly cleaning method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stone cultural relic protection, and in particular to a stone cultural relic surface paint cleaning method and application thereof. BACKGROUND

[0002] Stone cultural relics are important carriers of human history and culture. The surface of the stone cultural relics is often covered with paint layers such as polyurethane paint and epoxy resin paint due to artificial decoration, improper protection in modern times, or environmental pollution. These paint layers not only hide the original texture and color of the stone cultural relics, but also block the pores of the stone cultural relics, hinder the exchange of water vapor between the rock mass and the environment, accelerate the weathering and efflorescence of the rock mass, and seriously threaten the service life of the cultural relics.

[0003] In related technologies, Chinese patent CN116333524A discloses a cleaning agent for removing paint on the surface of stone cultural relics, which uses organic solvents such as benzyl alcohol and benzyl ether as core components. Although it is claimed to be harmless to stone cultural relics, the non-biological material has poor degradability, and the problem of insufficient penetration of thick paint layers has not been solved.

[0004] Chinese patent CN102500579A discloses a laser cleaning method for stone cultural relics. Although this method can achieve directional removal, dry laser action can easily produce plasma to block energy, and the single-time paint removal efficiency is low. For thick paint layers, multiple operations are required, and there is a potential risk of thermal damage to the oxidation film on the surface of stone cultural relics.

[0005] In summary, the existing technology cannot simultaneously meet the three core requirements of environmental protection, non-damage, and high efficiency for cultural relic protection, and there is an urgent need to develop a cleaning solution that is friendly to stone cultural relics and environmentally friendly. SUMMARY

[0006] The present application discloses a stone cultural relic surface paint cleaning method and application thereof, to solve the technical problems of incomplete cleaning and potential damage to stone cultural relics in related cleaning methods.

[0007] To solve the above problems, the present application adopts the following technical solutions: The first aspect of the present application provides a stone cultural relic surface paint cleaning method.

[0008] The stone cultural relic surface paint cleaning method of the present application comprises the following steps: Step 100, pretreatment: soft hair brush is used to remove dust on the surface of the stone cultural relics, and deionized water is used to wipe the surface of the stone cultural relics to remove water-soluble dirt and expose the complete paint film; Step 200, low-pressure sand blasting: sand blasting equipment is used to perform sand blasting treatment on the paint surface, wherein the sand blasting pressure is 0.1-0.3 MPa; Step 300, swelling: evenly apply the cleaning agent to the surface of the residual paint after sandblasting, and after standing, swell and soften the residual paint film, wherein the cleaning agent comprises the following ingredients by weight: phospholipid biosurfactant 5-20%, bio-based cosolvent 10-30%, thickening stabilizer 1-8%, and the balance is deionized water; Step 400, laser cleaning: using a pulsed laser device to clean the residual paint after swelling; Step 500, post-treatment: washing the cleaning area with deionized water to remove residual cleaning agent and paint debris, and naturally drying the surface of the stone cultural relics for protection treatment.

[0009] According to an optional embodiment, in step 200, the sandblasting abrasive is sodium bicarbonate particles and / or corn cob powder, and the particle size of the sodium bicarbonate particles and / or corn cob powder is 50-150 μm; and / or, in step 200, the particle size of the sandblasting abrasive is proportional to the thickness of the paint to be treated.

[0010] According to an optional embodiment, in step 200, when the thickness of the paint to be treated is <80 μm, the particle size of the abrasive is 50-80 μm; when the thickness of the paint is 80-150 μm, the particle size of the abrasive is 80-120 μm; and when the thickness of the paint is >150 μm, the particle size of the abrasive is 120-150 μm.

[0011] According to an optional embodiment, the phospholipid biosurfactant is one or more of soybean phospholipid, egg yolk phospholipid, phosphatidylcholine, and phosphatidylethanolamine, and the weight percentage of the phospholipid biosurfactant is 8-15%; and / or, the bio-based cosolvent is one or more of propylene glycol, glycerol, and polyethylene glycol 400, and the weight percentage of the bio-based cosolvent is 15-25%; and / or, the thickening stabilizer is one or more of hydroxypropyl methyl cellulose, guar gum, and xanthan gum, and the weight percentage of the thickening stabilizer is 2-6%.

[0012] According to an optional embodiment, when the cleaning agent is applied to the surface of the residual paint after sandblasting, a coating with a thickness of 0.3-1.5 mm is formed, and the residual paint film is swelled and softened after standing for 8-45 min.

[0013] According to an optional embodiment, when the thickness of the residual paint is <50 μm, stand for 8-15 min; when the thickness of the residual paint is 50-100 μm, stand for 15-30 min; and when the thickness of the residual paint is >100 μm, stand for 30-45 min.

[0014] According to an optional embodiment, in step 400, the laser wavelength is 1064 nm, the scanning speed is 200-800 mm / s, and the energy density is 0.4-1.4 J / cm 2 .

[0015] According to an optional embodiment, when the surface roughness of the stone cultural relic is less than 8 μm, the energy density is 0.4-0.8 J / cm 2 , the scanning speed is 600-800 mm / s; when the surface roughness is 8-40 μm, the energy density is 0.8-1.2 J / cm 2 , the scanning speed is 400-600 mm / s; and when the surface roughness is greater than 40 μm, the energy density is 1.2-1.4 J / cm 2 , the scanning speed is 200-400 mm / s.

[0016] According to an optional embodiment, in step 500, the deionized water used for flushing has a temperature of 20-25 ℃ and a pressure of 0.1 MPa; and / or, in step 500, when naturally drying, the temperature is maintained at 20-25 ℃, the relative humidity is 50-60%, and the drying time is 24-48 h; and / or, the method for protecting the surface of the stone cultural relic comprises spraying a 5% methyl triethoxysilane solution onto the surface of the stone cultural relic to form a silane protective film.

[0017] The second aspect of the present application provides an application of the method for cleaning paint on the surface of a stone cultural relic The application of the method for cleaning paint on the surface of a stone cultural relic according to any one of the technical solutions in the present application is suitable for cleaning one or more of polyurethane paint, epoxy resin paint, alkyd resin paint and nitro paint on the surface of a stone cultural relic, and the material of the stone cultural relic is one or more of sandstone, limestone, marble and granite.

[0018] The technical solution adopted by the present application can achieve the following beneficial effects: In the first aspect, the method for cleaning paint on the surface of a stone cultural relic comprises the following steps: removing thick paint on the surface of a stone cultural relic through low-pressure sand blasting, applying a cleaning agent to penetrate and chemically swell and soften the residual paint film through an interface, and finally removing micro residual paint by using a laser cleaning technology. Through the combination of the three steps of “low-pressure sand blasting-cleaning agent swelling-laser cleaning”, the sand blasting pressure can be reduced to avoid mechanical damage to the surface of the stone cultural relic. Through the synergy of the three steps, the total cleaning time of 200 μm thick epoxy resin paint is less than or equal to 90 min, and the paint removal rate is greater than or equal to 99.2%, which is more than 60% higher than the efficiency of a single cleaning method.

[0019] In the second aspect, the stone cultural relic surface paint cleaning method, when the cleaning agent swells, the cleaning agent selected takes phospholipid biological surfactant as the core, the 30-day biodegradation rate of the phospholipid biological surfactant is greater than or equal to 90%, is non-toxic and non-residual, is not only non-corrosive to the stone cultural relics, but also can avoid the harm of traditional organic solvents to the environment and the operating personnel. In addition, the stone cultural relic surface paint cleaning method also has the advantages of wide application range and convenient operation.

[0020] It can be seen that the stone cultural relic surface paint cleaning method can realize the unity of 'high-efficiency paint removal, cultural relic non-damage and environment-friendly' through the cooperation of 'low-pressure sand blasting, cleaning agent swelling and laser removal', and provides a new technical solution for removing stone cultural relic surface paint pollutants. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0022] The stone cultural relic surface paint cleaning method and its application provided by the present application will be described in detail below through specific embodiments and application scenarios.

[0023] The stone cultural relic surface paint cleaning method of the present embodiment includes the steps of pretreatment, low-pressure sand blasting, swelling, laser removal and post-treatment. Each step will be described in detail below.

[0024] Step 100, pretreatment. Soft hair brush is used to remove dust on the surface of the stone cultural relics, and then deionized water is used to wipe the surface of the stone cultural relics to remove water-soluble dirt and expose the complete paint film.

[0025] For example, first, the soft hair brush is used to gently sweep off the dust on the surface of the stone cultural relics to avoid scratching the surface in the subsequent sand blasting process; then, the dust-free cloth (cellulose material) soaked with deionized water is used to wipe the surface of the stone cultural relics to remove water-soluble salts and dirt on the surface of the stone cultural relics, expose the complete paint film, and ensure that the subsequent sand blasting, cleaning agent swelling and laser removal can be in full contact with the paint film.

[0026] Step 200, low-pressure sandblasting. A sandblasting device is used to sandblast the paint surface, wherein the sandblasting pressure is 0.1-0.3 MPa. For example, the sandblasting device is a portable low-pressure sandblasting device. The sandblasting pressure is 0.1 MPa, 0.15 MPa, 0.20 MPa, 0.25 MPa, or 0.30 MPa. For example, the sandblasting abrasive is sodium bicarbonate particles and / or corn cob powder. Specifically, the sandblasting abrasive can be uniformly sprayed onto the paint surface by compressed air. For example, the particle size of the sodium bicarbonate particles and / or corn cob powder is 50-150 μm.

[0027] The low-pressure sandblasting treatment of the present embodiment can quickly remove 30-70% of the thick layer of paint, especially for oil and gas layers with a paint thickness >100 μm. The low-pressure sandblasting of the present embodiment has a sandblasting pressure of 0.1-0.3 MPa, and uses soft sodium bicarbonate particles and / or corn cob powder as the sandblasting abrasive, which can avoid the risk of scratching the surface of stone cultural relics, and the sandblasting abrasive is easily dissolved in water, which can be completely removed by deionized water without any residue.

[0028] In some embodiments, the particle size of the sandblasting abrasive is determined based on the thickness of the paint to be treated. Preferably, the particle size of the sandblasting abrasive is proportional to the thickness of the paint to be treated. More preferably, when the thickness of the paint to be treated is <80 μm, the particle size of the abrasive is 50-80 μm; when the thickness of the paint is 80-150 μm, the particle size of the abrasive is 80-120 μm; and when the thickness of the paint is >150 μm, the particle size of the abrasive is 120-150 μm. The particle size of the sandblasting abrasive in the present embodiment is determined based on the thickness of the paint to be treated, which can further reduce the damage to stone cultural relics during low-pressure sandblasting treatment.

[0029] Step 300, swelling. The cleaning agent is uniformly applied to the residual paint surface after sandblasting, and after standing, the residual paint film is swelled and softened. Preferably, the cleaning agent comprises the following components by weight: phospholipid biosurfactant 5-20%, bio-based cosolvent 10-30%, thickening stabilizer 1-8%, and the balance is deionized water.

[0030] In some embodiments, the phospholipid biosurfactant is one or more of soybean phospholipid, egg yolk phospholipid, phosphatidylcholine, and phosphatidylethanolamine. Without limitation, the phospholipid biosurfactant can also be the remaining ingredients. Preferably, the weight percentage of the phospholipid biosurfactant is 8-15%. For example, the weight percentage of the phospholipid biosurfactant is 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%. Without limitation, the weight percentage of the phospholipid biosurfactant can also be the remaining weight percentages.

[0031] The embodiment selects one or more natural source components of soybean phospholipid, egg yolk phospholipid, phosphatidylcholine, and phosphatidylethanolamine, which have amphiphilic structures (hydrophilic group-phosphate group, hydrophobic group-fatty acid chain), can significantly reduce the interfacial tension between the cleaning agent and the paint film (from 35 mN / m to 18-22 mN / m), promote the penetration of the cleaning agent into the paint film, destroy the intermolecular force of the paint film, and achieve mild swelling; at the same time, the phospholipid biosurfactant has excellent biodegradability (30-day degradation rate ≥ 90%) and no toxicity, and has no corrosion to stone cultural relics.

[0032] When the cleaning agent swells, the selected cleaning agent takes the phospholipid biosurfactant as the core, the 30-day biodegradability of the phospholipid biosurfactant is ≥ 90%, it has no toxicity and no residue, it not only has no corrosion to stone cultural relics, but also can avoid the harm of traditional organic solvents to the environment and operating personnel.

[0033] In some embodiments, the bio-based cosolvent is one or more of propylene glycol, glycerol, and polyethylene glycol 400. Without limitation, the bio-based cosolvent can also be the remaining components. Preferably, the weight percentage of the bio-based cosolvent is 15-25%. Illustratively, the weight percentage of the bio-based cosolvent is 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, or 25%. Without limitation, the bio-based cosolvent can also be the remaining weight percentages.

[0034] The embodiment selects one or more biocompatible components of propylene glycol, glycerol, and polyethylene glycol 400, which can enhance the solubility of the phospholipid surfactant, and further improve the swelling ability of the cleaning agent to the paint; and the selected bio-based cosolvent has good compatibility with stone cultural relics and no risk of penetration damage.

[0035] In some embodiments, the thickening stabilizer is one or more of hydroxypropyl methyl cellulose, guar gum, and xanthan gum. Without limitation, the thickening stabilizer of the embodiment can also be the remaining components. Preferably, the weight percentage of the thickening stabilizer is 2-6%. Illustratively, the weight percentage of the thickening stabilizer is 2%, 3%, 4%, 5%, or 6%. Without limitation, the thickening stabilizer can also be the remaining weight percentages.

[0036] The embodiment selects one or more natural polymer components of hydroxypropyl methyl cellulose, guar gum, and xanthan gum, which can adjust the viscosity of the cleaning agent to 500-1500 mPa·s, ensure that the cleaning agent does not flow and drip after being applied on the surface of the stone cultural relics, can prolong the contact time of the cleaning agent and the paint film, and improve the swelling effect of the cleaning agent; at the same time, a protective film can also be formed on the stone surface to avoid the rapid evaporation of the cosolvent.

[0037] The cleaning agent of the embodiment has a residual amount of deionized water. The deionized water is used as a solvent to ensure uniform dispersion of each component and avoid erosion of the stone cultural relics by impurity ions (such as chloride ions and calcium ions).

[0038] In some embodiments, when the cleaning agent is applied to the surface of the residual paint after sandblasting, a coating with a thickness of 0.3-1.5 mm is formed. For example, the cleaning agent can be applied to the surface of the residual paint after sandblasting by using a soft brush or spraying.

[0039] For example, for a thin paint film, specifically when the paint thickness is less than 50 μm, the paint film is allowed to swell for 8-15 min, and the swelling degree of the paint film can reach 75-80%. For example, for a medium-thick paint film, specifically when the paint thickness is 50-100 μm, the paint film is allowed to swell for 15-30 min, and the swelling degree of the paint film can reach 80-88%. For example, for a thick paint film, specifically when the paint thickness is greater than 100 μm, the paint film is allowed to swell for 30-45 min, and the swelling degree of the paint film can reach 85-90%.

[0040] After the cleaning agent is swelled, the adhesion between the paint film and the stone substrate is significantly reduced, specifically from 1.2 MPa to 0.3-0.5 MPa, which lays a foundation for subsequent laser removal.

[0041] Step 400, laser removal. The swelled residual paint is removed by using a pulsed laser device. For example, a portable pulsed Nd:YAG laser device (wavelength 1064 nm, pulse width 10-20 ns) is used to accurately remove the swelled residual paint according to the surface roughness of the stone cultural relics.

[0042] In some embodiments, the scanning speed is 200-800 mm / s, and the energy density is 0.4-1.4 J / cm 2 . For example, when the surface roughness of the stone cultural relics is less than 8 μm (such as marble), the energy density is 0.4-0.8 J / cm 2 , and the scanning speed is 600-800 mm / s, which can avoid surface loss caused by high energy. For example, when the surface roughness is 8-40 μm (such as sandstone), the energy density is 0.8-1.2 J / cm 2 , and the scanning speed is 400-600 mm / s, which can balance the cleaning efficiency and damage risk. For example, when the surface roughness is greater than 40 μm (such as granite), the energy density is 1.2-1.4 J / cm 2 , and the scanning speed is 200-400 mm / s, which can ensure complete removal of the residual paint.

[0043] In the laser cleaning process of the embodiment, the scanning speed and energy density are controlled based on the roughness of the stone cultural relics surface, the laser energy is absorbed by the residual paint (absorption rate > 90%), and the residual paint is instantly gasified (temperature < 300℃). The absorption rate of the stone cultural relics to the laser with a wavelength of 1064nm is < 5%, and there is no risk of thermal damage.

[0044] Step 500, post-processing. The cleaning area is rinsed with deionized water to remove residual cleaning agent and paint debris, and the stone cultural relics surface is naturally dried and protected.

[0045] In some embodiments, the deionized water used for rinsing has a water temperature of 20-25℃ and a pressure of 0.1MPa. During natural drying, the temperature is maintained at 20-25℃, the relative humidity is 50-60%, and the drying time is 24-48h.

[0046] In some embodiments, the method for protecting the stone cultural relics surface is to spray a 5% methyl triethoxysilane solution onto the stone cultural relics surface to form a silane protective film, thereby improving the weather resistance of the stone cultural relics. However, the protective film can also be formed by other materials.

[0047] The stone cultural relics surface paint cleaning method of the embodiment first removes thick layer paint on the stone cultural relics surface by low-pressure sandblasting, then applies cleaning agent to penetrate and chemically swell and soften the residual paint film, and finally uses laser cleaning technology to remove trace residual paint. Through the combination of "low-pressure sandblasting-cleaning agent swelling-laser cleaning", not only can the sandblasting pressure be reduced to avoid mechanical damage to the stone cultural relics surface, but also through the synergy of the three, the total cleaning time of 200μm thick epoxy resin paint can be ≤90min, the paint removal rate is ≥99.2%, and the efficiency is improved by more than 60% compared to single cleaning method.

[0048] The stone cultural relics surface paint cleaning method of the embodiment, the cleaning system can be directly applied or sprayed, and the sandblasting and laser equipment are both portable (weight ≤6kg), without the need for complex installation, suitable for on-site protection operations of stone grottoes, open-air stone carvings and other cultural relics.

[0049] The stone cultural relics surface paint cleaning method of any one of the technical solutions in the embodiment is applicable to cleaning one or more of polyurethane paint, epoxy resin paint, alkyd resin paint, and nitro paint on the stone cultural relics surface, and the material of the stone cultural relics is one or more of sandstone, limestone, marble, and granite.

[0050] It can be seen that the stone cultural relic surface paint cleaning method of the embodiment is suitable for various paint types such as polyurethane paint and epoxy resin paint, and can be adapted to stone cultural relics of different materials and different surface roughnesses such as sandstone, limestone and marble by adjusting the sandblasting abrasive particle size, laser parameters and the like, and has a wide range of applications. Specifically, the stone cultural relic surface paint cleaning method of the embodiment can be applied to the non-destructive removal of paint contaminants on the surface of masonry cultural relics such as grotto temples, stone carvings and stone building components.

[0051] Example 1 The swelling effect of soybean phospholipid, egg yolk phospholipid and phosphatidylcholine on epoxy resin paint is compared in this embodiment.

[0052] (1) Provide the following three formulations of cleaning agents Formulation 1: soybean phospholipid 12%, propylene glycol 20%, hydroxypropyl methyl cellulose 4%, deionized water 64%.

[0053] Formulation 2: egg yolk phospholipid 12%, propylene glycol 20%, hydroxypropyl methyl cellulose 4%, deionized water 64%.

[0054] Formulation 3: phosphatidylcholine 12%, propylene glycol 20%, hydroxypropyl methyl cellulose 4%, deionized water 64%.

[0055] Preparation steps: add propylene glycol and deionized water to a reaction kettle with stirring device, stirring speed 300 r / min, mix for 5 min; slowly add one of soybean phospholipid, egg yolk phospholipid and phosphatidylcholine, increase the stirring speed to 400 r / min, stir for 15 min until the phospholipid is completely dissolved; add hydroxypropyl methyl cellulose, reduce the stirring speed to 350 r / min, stir for 20 min, adjust the viscosity to 1000 mPa·s, stand for 10 min to defoam, and the cleaning agent is obtained.

[0056] (2) Swelling performance test Select a marble sample of 5 cm x 5 cm x 2 cm, coat the surface with 100 μm thick epoxy resin paint, and apply the cleaning agent of the above three formulations respectively, with a thickness of 1 mm. After standing for 20 min, use a microhardness tester (HV-1000) to test the hardness change of the paint film after swelling, and calculate the swelling degree.

[0057] Swelling degree = (hardness before swelling - hardness after swelling) / hardness before swelling x 100% (3) Swelling performance test results Formulation 1 (soybean phospholipid): paint film swelling degree 88%, hardness after swelling from 25 HV to 3 HV, system penetration speed fast, paint film bubbling observed within 5 min.

[0058] Formulation 2 (egg yolk phospholipid): paint film swelling degree 85%, hardness after swelling from 25HV to 3.75HV, penetration speed slightly slow, bubbles observed in 8min.

[0059] Formulation 3 (phosphatidylcholine): paint film swelling degree 82%, hardness after swelling from 25HV to 4.5HV, penetration speed slowest, bubbles observed in 12min.

[0060] From the above comparison, it can be seen that the swelling effect of soybean phospholipid is the best, and the cleaning agent prepared by formulation 1 is preferred in subsequent examples.

[0061] (4) Degradation rate test According to the OECD 301B standard, the degradation of each formulation within 30 days was determined. The degradation rate of formulation 1 was 92.3%; the degradation rate of formulation 2 was 91.4%; the degradation rate of formulation 3 was 93.7%. It can be seen that the degradation rates of all formulations are greater than 90%, and the biodegradability is excellent.

[0062] Example 2 In this example, the cleaning agent prepared by formulation 1 is used to remove the epoxy resin paint on the surface of limestone in combination with low-pressure sandblasting and laser cleaning.

[0063] In this example, the limestone sample with a surface coated with 150μm thick epoxy resin paint, size 10cm×10cm×5cm, surface roughness 15μm, is cleaned by the following method.

[0064] (1) Preparation of cleaning agent According to the weight percentage: soybean phospholipid 12%, propylene glycol 20%, hydroxypropyl methyl cellulose 4%, deionized water 64%. Preparation steps: add propylene glycol and deionized water into a reaction kettle with stirring device, stirring speed 300r / min, mix for 5min; slowly add soybean phospholipid, increase the stirring speed to 400r / min, stir for 15min, until the phospholipid is completely dissolved; add hydroxypropyl methyl cellulose, reduce the stirring speed to 350r / min, stir for 20min, adjust the viscosity to 1000mPa·s, stand for 10min to defoam, and the cleaning agent is obtained.

[0065] (2) Cleaning steps Pretreatment: use a soft hair brush to sweep off the dust on the surface of the sample, use a dust-free cloth soaked with deionized water to wipe off, remove water-soluble dirt, and expose the complete paint film.

[0066] Low-pressure sandblasting: select 120μm particle size of sodium bicarbonate abrasive, sandblasting pressure 0.2MPa, sandblasting distance 15cm, uniform speed injection (speed 5cm / s), remove about 60% of the thick paint layer, residual paint thickness about 60μm.

[0067] Swelling: The cleaning agent was applied on the residual paint surface with a thickness of 1.2 mm, and left for 25 min. The paint film swelling degree reached 87%.

[0068] Laser cleaning: The residual paint after swelling was removed by using a pulsed laser device. The laser wavelength was 1064 nm, the energy density was 1.0 J / cm 2 , the scanning speed was 500 mm / s, the spot diameter was 80 μm, the scanning interval was 50 μm, and the residual paint was removed after 1 scan.

[0069] Post-processing: The laser cleaning area was rinsed with deionized water at a temperature of 25 °C and a pressure of 0.1 MPa. After natural drying for 24 h in an environment with a temperature of 25 °C and a relative humidity of 50%, a 5% methyltriethoxysilane solution was sprayed to form a silane protective film.

[0070] (3) Cleaning effect detection The test methods of each index are as follows, which are the same for subsequent examples.

[0071] Paint removal rate: The ratio of the cleaned paint area to the paint area before cleaning was tested.

[0072] Color difference ΔE: The color difference between the cleaned surface and the original rock color was tested based on GB / T 11186.3-1989.

[0073] Paint removal rate: Digital microscope observation showed that the residual paint area accounted for <0.5% after cleaning, i.e., the paint removal rate was >99.5%.

[0074] Color difference ΔE: Color difference meter test showed that ΔE = 1.5 before and after cleaning, which met the requirement of ΔE ≤ 2.0 in the cultural relic protection standard.

[0075] Surface integrity: Scanning electron microscope observation showed that the original texture and pore structure of the stone surface were intact, and there was no new crack or scratch.

[0076] Example 3 This example combined low-pressure sandblasting and laser cleaning to remove the polyurethane paint on the surface of sandstone.

[0077] This example aimed at a sandstone sample coated with 80 μm thick polyurethane paint, with a size of 8 cm × 8 cm × 4 cm and a surface roughness of 30 μm. The cleaning was performed as follows.

[0078] (1) Preparation of cleaning agent By weight percentage: soybean phospholipid 10%, glycerol 18%, guar gum 3%, deionized water 69%. Preparation steps: add glycerol and deionized water into a reaction kettle with stirring device, stirring speed 300 r / min, mix for 5 min; slowly add soybean phospholipid, increase the stirring speed to 400 r / min, stir for 15 min until the phospholipid is completely dissolved; add guar gum, reduce the stirring speed to 350 r / min, stir for 20 min, adjust the viscosity to 800 mPa·s, stand for 10 min to defoam, and the cleaning agent is obtained.

[0079] (2) Cleaning step Pre-treatment: use a soft hair brush to sweep off the floating dust on the surface of the sample, use a dust-free cloth soaked with deionized water to wipe, remove water-soluble dirt, and expose the complete paint film.

[0080] Low-pressure sandblasting: select 80 μm particle size of corn cob powder abrasive, sandblasting pressure 0.15 MPa, sandblasting distance 12 cm, uniform speed injection (speed 5 cm / s), remove about 50% of the thick paint layer, and the residual paint thickness is about 40 μm; Swelling: apply the cleaning agent on the surface of the residual paint, thickness 0.8 mm, stand for 10 min, and the swelling degree of the paint film reaches 83%.

[0081] Laser removal: use a pulsed laser device to remove the swollen residual paint. The laser wavelength is 1064 nm, the energy density is 1.2 J / cm 2 , the scanning speed is 400 mm / s, the spot diameter is 80 μm, the scanning interval is 50 μm, and the residual paint can be removed by scanning once; Post-treatment: use deionized water with water temperature 25℃ and pressure 0.1 MPa to rinse the laser removal area, naturally dry for 24 h in an environment with temperature 25℃ and relative humidity 50%, then spray 5% methyl triethoxysilane solution to form a silane protective film.

[0082] (3) Cleaning effect detection Paint removal rate: observe by using a digital microscope, the residual paint area accounts for <0.7% after cleaning, that is, the paint removal rate is >99.3%.

[0083] Color difference ΔE: test by using a color difference meter, ΔE=1.7 before and after cleaning, which meets the requirement of ΔE≤2.0 of the cultural relic protection standard.

[0084] Surface integrity: observe by using a scanning electron microscope, the original texture and pore structure of the stone surface are intact without damage, and the sandstone pores are not blocked.

[0085] Example 4 In this example, low-pressure sandblasting and laser removal are combined to remove the alkyd resin paint on the surface of marble.

[0086] This example is directed to a marble sample with a surface coated with 95 μm thick alkyd paint, size 10 cm x 10 cm x 5 cm, natural fracture surface roughness 38 μm, and is cleaned in the following manner.

[0087] (1) Preparation of cleaning agent By weight percentage: soybean phospholipid 5%, propylene glycol 10%, hydroxypropyl methyl cellulose 1%, deionized water 84%. Preparation steps: add propylene glycol and deionized water to a reaction kettle with stirring device, stirring speed 300 r / min, mix for 5 min; slowly add soybean phospholipid, increase stirring speed to 400 r / min, stir for 15 min until the phospholipid is completely dissolved; add hydroxypropyl methyl cellulose, reduce stirring speed to 350 r / min, stir for 20 min, adjust viscosity to 700 mPa·s, stand for 10 min to defoam, and the cleaning agent is obtained.

[0088] (2) Cleaning step Pretreatment: use a bristle brush to sweep off the dust on the surface of the sample, and use a dust-free cloth soaked with deionized water to wipe off the water-soluble dirt to expose the complete paint film.

[0089] Low-pressure sandblasting: select 110 μm particle size sodium bicarbonate abrasive, sandblasting pressure 0.1 MPa, sandblasting distance 15 cm, uniform speed spraying (speed 5 cm / s), remove about 55.8% of the thick paint layer, and the residual paint thickness is about 42 μm.

[0090] Swelling: apply the cleaning agent on the surface of the residual paint with a thickness of 1.1 mm, stand for 12 min, and the paint film swelling degree reaches 86%.

[0091] Laser cleaning: use a pulsed laser device to clean the residual paint after swelling. Laser wavelength 1064 nm, energy density 0.8 J / cm 2 , scanning speed 400 mm / s, spot diameter 80 μm, scanning interval 50 μm, and the residual paint can be removed by scanning once.

[0092] Post-treatment: rinse the laser cleaning area with deionized water at a water temperature of 25°C and a pressure of 0.1 MPa, maintain the temperature at 25°C, and naturally dry in an environment with a relative humidity of 50% for 36 h, then spray a 5% methyl triethoxysilane solution to form a silane protective film.

[0093] (3) Cleaning effect detection Paint removal rate: observe using a digital microscope, and the residual paint area accounts for <0.5% after cleaning, i.e. the paint removal rate is >99.5%.

[0094] Color difference ΔE: test using a color difference meter, ΔE before and after cleaning = 1.4, which meets the requirement of the cultural relic protection standard that ΔE ≤ 2.0.

[0095] Surface integrity: The original texture and pore structure of the stone surface were observed by scanning electron microscopy, and there were no new cracks or scratches.

[0096] Example 5 This example removes nitro paint from the surface of granite by low-pressure sandblasting and laser cleaning.

[0097] This example is directed to a granite sample with a 105 μm thick nitro paint coating on the surface, with dimensions of 10 cm x 10 cm x 5 cm, a natural fracture surface roughness of 32 μm, and is cleaned using the following method.

[0098] (1) Preparation of cleaning agent By weight percentage: soybean phospholipid 20%, propylene glycol 30%, hydroxypropyl methyl cellulose 8%, deionized water 42%. Preparation steps: add propylene glycol and deionized water to a reaction kettle with stirring device, stirring speed 300 r / min, mix for 5 min; slowly add soybean phospholipid, increase the stirring speed to 400 r / min, stir for 15 min until the phospholipid is completely dissolved; add hydroxypropyl methyl cellulose, reduce the stirring speed to 350 r / min, stir for 20 min, adjust the viscosity to 600 mPa·s, stand for 10 min to defoam, and the cleaning agent is obtained.

[0099] (2) Cleaning steps Pre-treatment: use a soft bristle brush to sweep off the dust on the surface of the sample, and use a dust-free cloth soaked with deionized water to wipe off the water-soluble dirt, exposing the complete paint film.

[0100] Low-pressure sandblasting: select 90 μm particle size sodium bicarbonate abrasive, sandblasting pressure 0.3 MPa, sandblasting distance 15 cm, uniform speed (speed 5 cm / s), remove about 57% of the thick paint layer, and the residual paint thickness is about 45 μm.

[0101] Swelling: apply the cleaning agent to the surface of the residual paint, with a thickness of 1.3 mm, stand for 8 min, and the paint film swelling degree reaches 94%.

[0102] Laser cleaning: use a pulsed laser device to clean the swollen residual paint. Laser wavelength 1064 nm, energy density 1.1 J / cm 2 , scanning speed 500 mm / s, spot diameter 70 μm, scanning interval 50 μm, and scanning 1 time can remove the residual paint.

[0103] Post-treatment: rinse the laser cleaning area with deionized water at a temperature of 25°C and a pressure of 0.1 MPa, maintain the temperature at 25°C, and naturally dry in an environment with a relative humidity of 50% for 36 h, then spray a 5% methyl triethoxy silane solution to form a silane protective film.

[0104] (3) Cleaning effect detection Paint removal rate: The digital microscope is used for observation, and the residual paint area accounts for less than 0.7% after cleaning, that is, the paint removal rate is greater than 99.3%.

[0105] Color difference ΔE: The color difference instrument is used for testing, and ΔE is 0.8 before and after cleaning, which meets the requirement of ΔE ≤ 2.0 of the cultural relic protection standard.

[0106] Surface integrity: The scanning electron microscope is used for observation, and the original texture and pore structure of the stone surface are intact without new cracks or scratches.

[0107] It can be seen that the stone cultural relic surface paint cleaning method of the application has a paint removal rate of greater than 99%, a stone surface color difference ΔE of less than 1.8 before and after cleaning, and no damage to the stone surface, which meets the requirements of the cultural relic protection standard.

[0108] It should be noted that in this paper, the term "includes", "contains" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "includes a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0109] In addition, it should be noted that the scope of the method and device in the embodiments of the application is not limited to performing functions in the order shown or discussed, but can also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0110] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, and any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A method for cleaning the surface paint of a stone cultural heritage, characterized by, It comprises the following steps: Step 100, pretreatment: remove dust on the surface of stone cultural relics with a soft brush, and then wipe the surface of stone cultural relics with deionized water to remove water-soluble dirt and expose the complete paint film; Step 200, low-pressure sandblasting: use a sandblasting device to sandblast the paint surface, wherein the sandblasting pressure is 0.1-0.3 MPa; Step 300, swelling: evenly apply the cleaning agent to the residual paint surface after sandblasting, and after standing, make the residual paint film swell and soften, wherein the cleaning agent comprises the following components by weight: phospholipid biological surfactant 5-20%, biological-based cosolvent 10-30%, thickening stabilizer 1-8%, and the balance is deionized water; Step 400, laser removal: use a pulsed laser device to remove the residual paint after swelling; Step 500, post-treatment: rinse the cleaning area with deionized water to remove residual cleaning agent and paint debris, and then naturally dry and perform protective treatment on the surface of stone cultural relics.

2. The method for cleaning the oil paint on the surface of a stone cultural relic according to claim 1, characterized by, In step 200, the sandblasting abrasive is sodium bicarbonate particles and / or corn cob powder, and the particle size of the sodium bicarbonate particles and / or corn cob powder is 50-150 μm; And / or, in step 200, the particle size of the sandblasting abrasive is proportional to the thickness of the paint to be treated.

3. The method for cleaning the oil paint on the surface of a stone cultural relic according to claim 2, characterized by, In step 200, when the thickness of the paint to be treated is <80 μm, the abrasive particle size is 50-80 μm; when the paint thickness is 80-150 μm, the abrasive particle size is 80-120 μm; and when the paint thickness is >150 μm, the abrasive particle size is 120-150 μm.

4. The method for cleaning the oil paint on the surface of a stone cultural relic according to claim 1, characterized by, The phospholipid biological surfactant is one or more of soybean phospholipid, egg yolk phospholipid, phosphatidylcholine, and phosphatidylethanolamine, and the weight percentage of the phospholipid biological surfactant is 8-15%; And / or, the biological-based cosolvent is one or more of propylene glycol, glycerol, and polyethylene glycol 400, and the weight percentage of the biological-based cosolvent is 15-25%; And / or, the thickening stabilizer is one or more of hydroxypropyl methyl cellulose, guar gum, and xanthan gum, and the weight percentage of the thickening stabilizer is 2-6%.

5. The method for cleaning the oil paint on the surface of a stone cultural relic according to claim 4, characterized in that, When the cleaning agent is applied to the residual paint surface after sandblasting, a coating with a thickness of 0.3-1.5 mm is formed, and the residual paint film is allowed to swell and soften after standing for 8-45 min.

6. The method for cleaning the oil paint on the surface of a stone cultural relic according to claim 5, characterized in that, When the residual paint thickness is <50 μm, stand for 8-15 min; when the residual paint thickness is 50-100 μm, stand for 15-30 min; and when the residual paint thickness is >100 μm, stand for 30-45 min.

7. The method for cleaning the oil paint on the surface of a stone cultural relic according to claim 1, wherein In step 400, the laser wavelength is 1064 nm, the scanning speed is 200-800 mm / s, and the energy density is 0.4-1.4 J / cm2 during laser cleaning. 2 .

8. The method for cleaning the oil paint on the surface of a stone cultural relic according to claim 7, characterized in that, When the roughness of the stone cultural relics is less than 8μm, the energy density is 0.4~0.8J / cm 2 , and the scanning speed is 600-800mm / s; when the roughness is 8~40μm, the energy density is 0.8~1.2J / cm 2 , and the scanning speed is 400-600mm / s; when the roughness is greater than 40μm, the energy density is 1.2~1.4J / cm 2 , and the scanning speed is 200-400mm / s.

9. The method for cleaning the oil paint on the surface of a stone cultural relic according to claim 1, wherein In step 500, the deionized water used for rinsing has a water temperature of 20-25°C and a pressure of 0.1 MPa; And / or, in step 500, when naturally drying, the temperature is maintained at 20-25°C, the relative humidity is 50-60%, and the drying time is 24-48 h; And / or, the method of performing protective treatment on the surface of stone cultural relics is to spray a 5% methyl triethoxysilane solution onto the surface of stone cultural relics to form a silane protective film.

10. Use of the method for cleaning oil paint on a surface of a stone cultural heritage according to any one of claims 1 to 9, characterized in that, The method is suitable for cleaning one or more of polyurethane paint, epoxy resin paint, alkyd resin paint and nitro paint on the surface of the stone cultural relics, and the stone cultural relics are made of one or more of sandstone, limestone, marble and granite.