Surface cleaning method and device for leather cultural relics

Abstract

The present invention relates to the technical field of cultural relic protection, and discloses a surface cleaning method and device for leather cultural relics, the method comprising the following steps: (1) wetting the surface of the leather cultural relic part to be cleaned with a cleaning liquid, and then placing a hydrogel adsorption wet tissue on the surface; (2) fixing the hydrogel adsorption wet tissue around the periphery, and simultaneously performing ultrasonic and negative pressure adsorption on the surface; the frequency of the ultrasonic wave is 20-80kHz; the intensity of the negative pressure adsorption is 0-0.2kPa; (3) then removing the hydrogel adsorption wet tissue to complete the surface cleaning of the leather cultural relic. The present invention can better clean the pollutants on the surface and under the surface of the leather cultural relic, especially has an obvious cleaning and removal effect on the small molecule pollutants embedded between collagen fibers, and the physical properties and structural properties of the leather cultural relic after cleaning do not change.

Description

Technical Field

[0001] The invention relates to the technical field of cultural relics protection, and in particular to a surface cleaning method and device for leather cultural relics. Background Art

[0002] There are a large number of leather cultural relics unearthed or handed down in my country, which are of great value for verifying Chinese civilization. At the same time, many leather cultural relics are still discovered in archaeological excavations every year. However, due to the organic properties of leather cultural relics, they are easily affected by the burial environment and preservation environment and suffer from different types of diseases, including pollution, dryness, incompleteness, cracking, decay, etc., which make it difficult to preserve the cultural relics for a long time. In particular, pollutants such as protein and fat produced by the decay of corpses in the burial environment, calcium, aluminum, iron and sodium mineral salts, free metal ions after corrosion of metal objects, acids and alkalis in the soil and free hydrogen ions and hydroxide ions, organic residues, etc. These pollutants still adhere to the surface of the cultural relics or penetrate into their structure after being unearthed, and continue to cause damage to the cultural relics. Therefore, cleaning of pollutants is a key step and primary task in cultural relic protection.

[0003] At present, there are two main methods for cleaning leather cultural relics: water washing and dry cleaning. Water washing directly uses water, alcohol, and cleaning liquid for soaking and cleaning, but the water washing method is easy to affect the structure of leather cultural relics, easily cause swelling and cracking of collagen, and the surface dyes or pigments are easy to fade and fall off. Most of the existing natural cleaning liquids that can be used for silk, paper, and bamboo and wood lacquerware contain natural surfactants that cause lipid saponification and loss, which are not suitable for leather cultural relics. They are easy to destroy the relative balance of collagen, lipids and water content in the main components of leather cultural relics. Although they can remove pollutants to a certain extent, they also indirectly cause the loss of the main components of leather cultural relics, resulting in the risk of damage to cultural relics. Therefore, there is no natural and environmentally friendly cleaning liquid for leather cultural relics. Dry cleaning uses chemical reagents such as acetone, carbon tetrachloride, tetrachloroethylene, and petroleum solvents to dissolve pollutants and then wipe them, but the dry cleaning method is easy to cause the loss of water molecules and lipids in the structure of leather cultural relics, resulting in deformation of the collagen network structure, easy breakage of collagen fibers, and easy fading and falling of surface dyes or pigments. In summary, both of the two common methods currently have certain risks to the safety of cultural relics, and there is an urgent need for a method and device suitable for cleaning leather cultural relics. Summary of the invention

[0004] In order to solve the above-mentioned technical problems, the present invention provides a surface cleaning method and device for leather cultural relics. By adopting cleaning liquid and hydrogel wet wipes, and simultaneously using ultrasonic and negative pressure adsorption, pollutants dissolved and dispersed in the cleaning liquid are adsorbed onto wet wipes, thereby allowing the pollutants to be completely separated from the cultural relics, thereby achieving the purpose of cleaning the surface of leather cultural relics, and will not change the physical properties and structural properties of the leather cultural relics, or damage the collagen fibers.

[0005] The specific technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for surface cleaning of leather cultural relics, comprising the following steps:

[0007] (1) Wet the surface of the leather cultural relics to be cleaned with a cleaning solution, and then place a hydrogel adsorption wet tissue on the surface;

[0008] (2) Fix the four sides of the hydrogel adsorption wet tissue and simultaneously perform ultrasonic and negative pressure adsorption on its surface; the frequency of the ultrasonic wave is 20 - 80 kHz; the intensity of the negative pressure adsorption is 0 - 0.2 kPa;

[0009] (3) Then remove the hydrogel adsorption wet tissue to complete the surface cleaning of the leather cultural relics.

[0010] In view of the current common situation that precious leather cultural relics are polluted by the burial environment, the present invention adopts a natural and environmentally friendly new cleaning solution and a non-destructive cleaning method. The main principle is: when in use, the hydrogel adsorption wet tissue will adhere to the surface of the cultural relics. First, the cleaning solution is used to separate the collagen fibers in the leather cultural relics from the pollutants through lubrication and relaxation effects, and reduce the adhesion of pollutants to the collagen fibers as much as possible. Then, the short wave of the ultrasonic wave is conducted to the surface layer of the wetted cultural relics through the hydrogel wet tissue, and the ultrasonic wave is conducted to the cleaning solution in the leather surface layer, causing high-frequency vibration of the cleaning solution in the surface layer of the leather cultural relics. By using the vibration of water molecules and the emulsification effect of surfactants in the cleaning solution, the pollutants are dissolved or detached. At the same time, negative pressure adsorption is adopted to adsorb the pollutant small molecules in the depth range of 0 - 0.1 mm under the leather surface layer or the pollutant small molecules dissolved and dispersed in the cleaning solution onto the wet tissue. Since the wet tissue has a gel function, it plays an adhesive role on the pollutants, so that the pollutants are completely separated from the cultural relics, achieving the purpose of surface cleaning of the leather cultural relics.

[0011] Preferably, the preparation method of the cleaning solution is: add water-soluble lanolin, tea saponin, phospholipid, and bacillus licheniformis protease into an ethanol aqueous solution and mix at room temperature.

[0012] Leather cultural relics are relatively precious, and the cleaning solution used is preferably natural and environmentally friendly, and the residue will not affect the leather, so the cleaning solution components of the present invention are all from natural substances. Since leather cultural relics are affected by the burial environment, they often become hard after being unearthed. This is because the skin loses water and lipids, the collagen fibers shrink and squeeze together, causing the leather skin to deform and break. The purpose of using water-soluble lanolin is to infiltrate the collagen fibers in the leather cultural relics, which can increase the distance between the collagen fibers, so that the pollutants can be quickly dissolved in the cleaning solution or separated from the collagen fibers. The purpose of using tea saponin and phospholipids is to disperse the small molecules of pollutants in the cleaning solution under the action of ultrasound, and tea saponin and phospholipids are both excellent natural surfactants, and tea saponin has a certain antibacterial effect, and phospholipids have the effect of lubricating collagen fibers. The purpose of using licheniformis protease is to use its biological activity to strip the pollutants on the collagen fibers, including some minerals and organic matter that affect collagen. The purpose of using ethanol is to dissolve or strip some organic pollutants that are difficult to dissolve in water.

[0013] The composite formula of the cleaning liquid of the present invention can dissolve and loosen the common mineral and organic pollutants in the tomb environment. It adopts natural materials and has safe ingredients. Moreover, during the cleaning process, it can soften the leather cultural relics to a certain extent, that is, lubricate the collagen fibers, improve their hardness, and enhance their softness, which is also conducive to the implementation of subsequent ultrasonic and negative pressure adsorption cleaning.

[0014] Preferably, the mass volume ratio of the water-soluble lanolin, tea saponin, phospholipids, Bacillus licheniformis protease and ethanol aqueous solution is 0.1-0.5g:0.01-0.05g:0.1-0.5g:0.1-0.5g:20mL; the mass ratio of ethanol to water in the ethanol aqueous solution is 1:2-10.

[0015] Preferably, the wet tissue preparation method is: adding gelatin, sodium alginate and glycerol into water at room temperature to obtain a treatment solution; then soaking the chitosan non-woven fabric in the treatment solution for not less than 30 minutes, taking it out and hanging it until no water drops, and packaging it so that it does not dry out to obtain a hydrogel adsorbed wet tissue.

[0016] The chitosan non-woven fabric is selected as the wet tissue substrate, mainly for the purpose of being able to form a hydrogel with gelatin and sodium alginate. The hydrogel is a polymer material that can contain a large amount of water and has a certain gel adsorption effect. Compared with the existing polyacrylic acid gel, the raw materials used in the gel of the present invention are all from natural substances, which will not affect the cultural relics and the environment, can better conduct ultrasonic waves to the cleaning liquid, and can better adsorb pollutants and surfactants in the cleaning liquid, so that the cleaning liquid components are minimized in the leather cultural relics.

[0017] Preferably, the mass-volume ratio of the gelatin, sodium alginate, glycerol and water is 0.1-0.5 g: 0.1-0.5 g: 0.1-0.5 g: 20 mL; the thickness of the chitosan non-woven fabric does not exceed 1 mm.

[0018] Preferably, the thickness of the hydrogel adsorbed wet tissue does not exceed 1 mm.

[0019] In a second aspect, the present invention also provides a cleaning device for the surface of leather cultural relics. The cleaning device includes a power regulator and a cleaning head connected to the power regulator and placed outside the power regulator; the power regulator includes an ultrasonic generator and a negative pressure vacuum pump provided inside it; the cleaning head includes an ultrasonic transducer and a negative pressure adsorption tube; the ultrasonic transducer is connected to the ultrasonic generator; the negative pressure adsorption tube is connected to the negative pressure vacuum pump.

[0020] The cleaning head has two main functions. One is to use the ultrasonic transducer to cause the pollutants to loosen and detach between the collagen fibers, and the other is to use negative pressure adsorption to suck the pollutants away from between the collagen fibers, ultimately achieving the purpose of cleaning. The main function of the power regulator is to adjust the corresponding ultrasonic frequency and negative pressure suction intensity according to the aging degree of the cultural relics. Facing precious and fragile cultural relics, appropriate parameters can be selected on the premise of judging according to the aging degree to achieve the best cleaning effect without harming the cultural relics. The principles of the ultrasonic generator and the ultrasonic transducer are as follows: A signal generator generates a signal with a specific frequency. This signal can be a sine signal or a pulse signal. Then, the ultrasonic transducer converts this specific frequency signal into high-frequency mechanical vibration and propagates it into the aqueous solution medium. Due to the non-linear effect of ultrasonic waves when propagating in liquids, cavitation effects will occur, causing tens of thousands of tiny bubbles to be generated in the liquid. The closure of the bubbles can form an instantaneous high pressure exceeding 1000 atmospheric pressures, continuously impacting the surface of the object, causing the pollutants attached to the surface of the object to peel off and dispersing them into the cleaning solution. The principle of the negative pressure vacuum pump is as follows: The circular motion of the motor, through a mechanical device, makes the diaphragm inside the pump move reciprocally, thereby compressing and stretching the air in the pump cavity to form negative pressure. A pressure difference is generated between the air suction port and the external atmospheric pressure. Under the action of the pressure difference, the gas is sucked into the pump cavity and then discharged from the exhaust port.

[0021] Preferably, the power regulator further includes a sound wave power regulator and a negative pressure regulator provided outside it; the sound wave power regulator is connected to the ultrasonic generator; the negative pressure regulator is connected to the negative pressure vacuum pump.

[0022] Preferably, the sound wave power regulator has three gears of sound wave frequency adjustment of 20 kHz, 40 kHz, and 80 kHz; the negative pressure regulator has a negative pressure suction intensity adjustment in the range of 0-0.2 kPa.

[0023] The ultrasonic transducer mainly consists of a piezoelectric ceramic element, front and rear metal cover plates, a prestressed screw, electrode plates, an aluminum radiation surface, and an insulating tube. Its principle is to use piezoelectric ceramics with a frequency equal to its resonance frequency and utilize its piezoelectric effect to convert electrical energy into mechanical vibration. During operation, first, an ultrasonic generator generates ultrasonic waves, which are converted into mechanical vibrations by the ultrasonic transducer and then conducted to the cleaning liquid on the surface of the hydrogel adsorption wet tissue and leather through the aluminum radiation surface to achieve the purpose of cleaning the pollutants on the leather surface. The negative pressure adsorption tube is made of PVC hose and is connected to a negative pressure vacuum pump. The air negative pressure generated by the negative pressure vacuum pump forms an inhalation power at the mouth of the negative pressure adsorption tube to suck the pollutants and liquid into the tube. The diameter of the negative pressure adsorption tube should not exceed 2 cm, which is related to the maximum negative pressure of 0.2 kPa generated by the negative pressure vacuum pump. If the diameter is too large, it is not easy to form a corresponding suction force at the adsorption tube mouth, and the adsorption effect will decline.

[0024] Preferably, the ultrasonic transducer and the negative pressure adsorption tube in the cleaning head are fixed, and when acting on the surface of the hydrogel adsorption wet tissue, the ultrasonic transducer is placed in front of the negative pressure adsorption tube and the cleaning head is moved from front to back on the surface.

[0025] When the cleaning head moves, first, the cleaning liquid dissolves the pollutants through the ultrasonic vibration of water molecules, and then it is quickly adsorbed through negative pressure. The key to the design of the cleaning head is that when the pollutants just become smaller pollutant molecules with a smaller particle size in the ultrasonic vibration solution environment, they can be adsorbed and separated from the leather surface in time through the aqueous solution in the wet tissue and the trace aqueous solution after surface infiltration, avoiding the self-aggregation of pollutant molecules in the trace aqueous solution on the leather surface for too long, resulting in an increase in particle size and poor or ineffective removal.

[0026] According to a large number of experiments, the values of the acoustic power and negative pressure suction intensity required for different aging degrees should be different to ensure that the pollutants can be removed while avoiding excessive power from affecting the surface properties of cultural relics. According to the experiments, a relationship table (Table 1) of three levels of ultrasonic power, negative pressure suction intensity, and corresponding aging degrees was obtained. The experimental results show that the pollution degrees and aging degrees of leather cultural relics are different. First, use a microscope to observe the microscopic morphology of the aging of leather cultural relics ( Figure 6 ), and at the same time, use an infrared spectrometer to measure the absorption peak intensities of the samples at 1620 ± 3 cm -1 and 1521 ± 3 cm -1 . The absorption peaks at 1620 ± 3 cm -1 and 1521 ± 3 cm -1 are the characteristic absorption peaks of amide I and amide II in leather collagen. According to previous research, the (1620 ± 3 / 1521 ± 3) cm -1The peak intensity ratio is 0.91. It is considered that during the leather aging process, the ratio of the characteristic absorption peaks of amide I and amide II will continuously increase. Based on the leather simulated aging research and the infrared spectrum tests of cultural relics in different aging states, we established the relationship between the absorption peak intensity ratio of 1620±3 cm -1 and 1521±3 cm -1 and the aging degree (Table 1). Based on this, we speculated its aging degree, and then set the ultrasonic frequency and negative pressure suction intensity parameters.

[0027] Observe the surface of leather cultural relics under a microscope at 50X - 200X magnification. If cracks and exfoliated particles are found on the surface of the cultural relics, in a unit area of 100μm X 100μm, the total crack length is more than 1000μm, the particle area is more than 1 / 2 unit area, or in the infrared spectrum test, the (1620±3 / 1521±3) cm -1 peak intensity ratio is between 0.971 - 1, indicating that the cultural relics are severely aged, the collagen network structure is damaged, and the strength of collagen fibers decreases significantly. Parameters with an ultrasonic frequency of 20kHz and a negative pressure suction intensity in the range of 0 - 0.05kPa need to be used. Although the cleaning effect is not as good as that of high-frequency sound waves and high-strength negative pressure, it will not affect the cultural relics. Compared with the existing cleaning technology, it can effectively solve the cleaning problem of severely aged leather cultural relics.

[0028] If cracks and exfoliated particles are observed on the surface of leather cultural relics under the microscope, in a unit area of 100μm X 100μm, the total crack length is between 100 - 1000μm, the particle area is between 0 - 1 / 2 unit area, or in the infrared spectrum test, the (1620±3 / 1521±3) cm -1 peak intensity ratio is between 0.941 - 0.97, indicating that the cultural relics are moderately aged. Parameters with an ultrasonic frequency of 40kHz and a negative pressure suction intensity in the range of 0.05 - 0.1kPa can be used to achieve the best cleaning effect without damaging the cultural relics;

[0029] If cracks are observed on the surface of leather cultural relics under the microscope and there are no exfoliated particles, in a unit area of 100μm X 100μm, the total crack length is less than 100μm, or in the infrared spectrum test, the (1620±3 / 1521±3) cm -1When the peak intensity ratio is between 0.91 and 0.94, it is considered that the aging of the cultural relics is slight. Parameters such as an ultrasonic frequency of 80 kHz and a negative pressure suction intensity in the range of 0.1 - 0.2 kPa can be adopted. If an ultrasonic frequency greater than 80 kHz is used, even modern leather is likely to cause damage to collagen fibers. If a negative pressure suction intensity greater than 0.2 kPa is used, the original coating on the surface of leather cultural relics is likely to be detached, presenting certain technical risks. Therefore, in the present invention, the ultrasonic frequency is set not higher than 80 kHz, and the negative pressure suction intensity is not higher than 0.2 kPa.

[0030] After using the cleaning head to perform ultrasonic and negative pressure adsorption on the surface of the leather cultural relic once, observe the cleaning effect of the pollutants in Area 1 after the cleaning head moves. It is found that there is still some residue of the pollutants. Continue to use a cotton swab to dip the cleaning solution to moisten the area where the pollutants remain, place an unused one-layer gel adsorption wet tissue, and use the cleaning head to perform ultrasonic and negative pressure adsorption on the surface again.

[0031] Table 1 Relationship between ultrasonic power, negative pressure suction intensity and aging degree of leather cultural relics

[0032]

[0033] Preferably, the cleaning device further includes a recovery tank connected to the power regulator and placed outside the power regulator; the ultrasonic transducer is connected to the ultrasonic generator through a power cord.

[0034] The recovery tank is connected to the negative pressure vacuum pump, and its function is to recover the pollutant solution continuously adsorbed and accumulated by the hydrogel wet tissue. When it exceeds the maximum water content of the wet tissue, the overflowing pollutant solution can be recovered in time to avoid dripping on the cultural relics again.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] (1) The present invention can clean the pollutants on the surface and in the depth range of 0 - 0.1 mm under the surface of the leather cultural relics well, especially has an obvious cleaning and removing effect on small molecule pollutants embedded between collagen fibers, and the physical properties and structural properties of the leather cultural relics after cleaning do not change;

[0037] (2) The cleaning solution of the present invention has a simple formula, the raw materials are easily obtainable, and the components will not cause damage to the leather cultural relics. Among them, water-soluble lanolin can play a role in fatliquoring and maintenance, tea saponin will play an antibacterial role, and phospholipids play a role in softening and cleaning at the same time, enhancing the performance of the leather cultural relics itself while cleaning. The cleaning solution has good solubility and fluidity, can be smoothly adsorbed from the leather surface to the wet tissue through negative pressure, and the residual amount of the cleaning solution is extremely small;

[0038] (3) The preparation process of the gel adsorption wet wipes of the present invention is simple and practical. The gel polymer obtained from chitosan, gelatin, and sodium alginate has good adsorption effect, and the adsorbed small pollutant molecules are not easy to fall off. The gel polymer formula is environmentally friendly and will not adhere to cultural relics and cause impact on them;

[0039] (4) The device of the present invention is assembled with ultrasonic and negative pressure adsorption components, which can quickly remove pollutants. The acting forces of ultrasonic and negative pressure adsorption will not cause impact on cultural relics, including the pigments and dyes on the surface of cultural relics, and the power parameters can be adjusted according to the degree of pollution, which is convenient for cleaning leather cultural relics with different aging degrees. The device itself is light, and there is a gel adsorption wet wipe buffer below, with high cultural relic safety and strong operability. Description of the Drawings

[0040] Figure 1 is a schematic structural diagram of the cleaning device of the present invention;

[0041] Figure 2 is an infrared spectrogram of the gel polymer and raw materials in the hydrogel adsorption wet wipe;

[0042] Figure 3 is a microscopic image of the unearthed leather cultural relic fragment and three different areas before and after cleaning;

[0043] Figure 4 is the X-ray fluorescence spectroscopy analysis result of the unearthed leather cultural relic fragment and three different areas before and after cleaning;

[0044] Figure 5 is an energy spectrum diagram of the leather cultural relic simulation sample before and after cleaning using different reagent formulations;

[0045] Figure 6 is a microscopic image of different aging degrees of leather cultural relics.

[0046] The reference signs in the drawings are: cleaning head 1, power regulator 2, recovery tank 3, ultrasonic transducer 4, negative pressure adsorption tube 5, power cord 6, ultrasonic generator 7, acoustic power regulator 8, negative pressure vacuum pump 9, negative pressure pressure regulator 10. Detailed Embodiments

[0047] The present invention will be further described below in conjunction with embodiments.

[0048] Example 1 (Leather cultural relic fragment, Area 1, Moderate aging)

[0049] As Figure 1The following is a schematic structural diagram of the cleaning device of the present invention. The cleaning device includes a cleaning head 1, a power regulator 2, and a recovery tank 3. Both the cleaning head 1 and the recovery tank 3 are connected to the power regulator 2 and are disposed outside it. The cleaning head 1 includes a fixed ultrasonic transducer 4 and a negative pressure adsorption tube 5. The ultrasonic transducer 4 is connected to the power regulator 2 through a power cord 6, while the negative pressure adsorption tube 5 is directly connected to the power regulator 2. Inside the power regulator 2, there is an ultrasonic generator 7 and a negative pressure vacuum pump 9, and outside there are an acoustic power regulator 8 and a negative pressure regulator 10 for adjusting the ultrasonic power and the negative pressure respectively. Specifically, the ultrasonic generator 7 is connected to the ultrasonic transducer 4 and the acoustic power regulator 8 respectively, and the negative pressure vacuum pump 9 is connected to the negative pressure adsorption tube 5 and the negative pressure regulator 10 respectively. The acoustic power regulator 8 has three gears of acoustic frequency regulation at 20 kHz, 40 kHz, and 80 kHz, and the negative pressure regulator 10 is for adjusting the negative pressure suction intensity in the range of 0 - 0.2 KPa. In addition, the negative pressure vacuum pump 9 is also connected to the recovery tank 3.

[0050] The method for cleaning the surface of leather cultural relics includes the following steps:

[0051] (1) Add 0.1 g of water-soluble lanolin, 0.01 g of saponin, 0.1 g of phospholipid, and 0.1 g of Bacillus licheniformis protease to 20 mL of a mixed solution of ethanol and water with a mass ratio of 1:2 at room temperature to obtain a cleaning solution;

[0052] (2) Add 0.1 g of gelatin, 0.5 g of sodium alginate, and 0.5 g of glycerol to 20 mL of water at room temperature to obtain a treatment solution. Then soak a chitosan non-woven fabric with a thickness of 0.2 mm in the treatment solution for 60 min, take it out and hang it until no water drops, to obtain a hydrogel adsorption wet tissue;

[0053] (3) Dip a cotton swab in the cleaning solution to moisten area one of the leather cultural relic fragment, and place a layer of the above-mentioned gel adsorption wet tissue on its surface;

[0054] (4) Fix the four sides of the gel adsorption wet tissue, turn on the cleaning device, set the ultrasonic frequency to 40 kHz and the negative pressure to 0.1 kPa; press the cleaning head on the device tightly against the wet tissue, place the ultrasonic transducer in front of the negative pressure adsorption tube and slowly move the cleaning head from front to back on the surface. During the movement of the cleaning head, the wet tissue always fits with the surface of the cultural relic;

[0055] (5) Observe the cleaning effect of the pollutants in area one after the cleaning head moves. It is found that there are still some pollutants remaining. Continue to dip a cotton swab in the cleaning solution to moisten the pollutant remaining part, place an unused layer of the above-mentioned gel adsorption wet tissue, and use the cleaning head to perform ultrasonic and negative pressure adsorption on the surface again;

[0056] (6) Then remove the cleaning head, take off the wet tissue, and use an X-ray fluorescence spectrometer to test and analyze the elemental content of the pollutants on the surface of the cultural relic. After analysis, it is considered that the pollutants have been cleaned, and the surface cleaning of the leather cultural relic fragment is completed.

[0057] Comparative Example 1 (leather cultural relic fragment, Region 2, moderately aged)

[0058] The difference from Example 1 is that: in step (2), untreated non-woven fabric is used, that is, chitosan non-woven fabric is not used.

[0059] The surface cleaning method of leather cultural relics includes the following steps:

[0060] (1) Add 0.1 g of water-soluble lanolin, 0.01 g of saponin, 0.1 g of phospholipid, and 0.1 g of Bacillus licheniformis protease to 20 mL of a mixed solution of ethanol and water with a mass ratio of 1:2 at room temperature to obtain a cleaning solution;

[0061] (2) Add 0.1 g of gelatin, 0.5 g of sodium alginate, and 0.5 g of glycerin to 20 mL of water at room temperature to obtain a treatment solution. Then soak ordinary non-woven fabric with a thickness of 0.2 mm (not treated with chitosan) in the treatment solution for 60 min, take it out and hang it until no water drops, to obtain a hydrogel adsorption wet tissue;

[0062] (3) Use a cotton swab to dip the cleaning solution to moisten Region 1 of the leather cultural relic fragment, and place a layer of the above-mentioned gel adsorption wet tissue on its surface;

[0063] (4) Fix the four sides of the gel adsorption wet tissue, turn on the cleaning device, set the ultrasonic frequency to 40 kHz, and the negative pressure to 0.1 kPa; press the cleaning head of the device tightly against the wet tissue, place the ultrasonic transducer in front of the negative pressure adsorption tube and move the cleaning head slowly from front to back on the surface. During the movement of the cleaning head, the wet tissue always fits with the surface of the cultural relic;

[0064] (5) Observe the cleaning effect of the pollutants in Region 1 after the cleaning head moves. It is found that there are still some pollutants remaining. Continue to use a cotton swab to dip the cleaning solution to moisten the pollutant remaining part, place an unused layer of the above-mentioned gel adsorption wet tissue, and use the cleaning head to perform ultrasonic and negative pressure adsorption on the surface again;

[0065] (6) Repeat the cleaning 5 times according to step (5). Then remove the cleaning head, take off the wet tissue, and use an X-ray fluorescence spectrometer to test and analyze the elemental content of the pollutants on the surface of the cultural relic. After analysis, it is considered that the pollutants in Region 2 have not been completely removed.

[0066] Comparative Example 2 (leather cultural relic fragment, Region 3, moderately aged)

[0067] The difference from Example 1 is that during the cleaning process, the ultrasonic device was not turned on, and only negative pressure adsorption was performed.

[0068] The method for cleaning the surface of leather cultural relics includes the following steps:

[0069] (1) Add 0.1 g of water-soluble lanolin, 0.01 g of saponin, 0.1 g of phospholipid, and 0.1 g of Bacillus licheniformis protease to 20 mL of a mixed solution of ethanol and water with a mass ratio of 1:2 at room temperature to obtain a cleaning solution;

[0070] (2) Add 0.1 g of gelatin, 0.5 g of sodium alginate, and 0.5 g of glycerol to 20 mL of water at room temperature to obtain a treatment solution. Then soak a chitosan non-woven fabric with a thickness of 0.2 mm in the treatment solution for 60 min, take it out and hang it until no water drips, to obtain a hydrogel adsorption wet tissue;

[0071] (3) Use a cotton swab to dip the cleaning solution to moisten Area 1 of the leather cultural relic fragment, and place a layer of the above-mentioned gel adsorption wet tissue on its surface;

[0072] (4) Fix the four sides of the gel adsorption wet tissue, turn on the cleaning device, and set the negative pressure to 0.1 kPa; press the cleaning head on the device tightly against the wet tissue and move it slowly on the surface. During the movement of the cleaning head, the wet tissue always fits with the surface of the cultural relic;

[0073] (5) Observe the cleaning effect of the pollutants in Area 1 after the cleaning head moves. It is found that there are still some pollutants remaining. Continue to use a cotton swab to dip the cleaning solution to moisten the pollutant residue area, place an unused layer of the above-mentioned gel adsorption wet tissue, and use the cleaning head to perform negative pressure adsorption on the surface again;

[0074] (6) Repeat the cleaning 5 times according to step (5). Then remove the cleaning head, take off the wet tissue, and use an X-ray fluorescence spectrometer to test and analyze the elemental content of the pollutants on the surface of the cultural relic. After analysis, it is considered that the pollutants in Area 3 have not been completely removed.

[0075] Example 2 (simulated aging pollution sample that can replace leather cultural relics, slightly aged)

[0076] The method for cleaning the surface of leather cultural relics includes the following steps:

[0077] (1) Add 0.1 g of water-soluble lanolin, 0.03 g of saponin, 0.2 g of phospholipid, and 0.5 g of Bacillus licheniformis protease to 20 mL of a mixed solution of ethanol and water with a mass ratio of 1:4 at room temperature to obtain a cleaning solution;

[0078] (2) Add 0.2 g of gelatin, 0.2 g of sodium alginate, and 0.3 g of glycerol to 20 mL of water at room temperature to obtain a treatment solution. Then immerse a chitosan non-woven fabric with a thickness of 0.1 mm in the treatment solution for 60 min. After taking it out, hang it until no water drops, and obtain a hydrogel adsorption wet tissue;

[0079] (3) Dip a cotton swab in the cleaning solution to moisten the simulated aged and contaminated sample, and place a layer of the above gel adsorption wet tissue on its surface; (4) Fix the four sides of the gel adsorption wet tissue, turn on the cleaning device, set the ultrasonic frequency to 80 kHz, and the negative pressure to 0.2 kPa; Press the cleaning head on the device tightly against the wet tissue, place the ultrasonic transducer before the negative pressure adsorption tube, and slowly move the cleaning head from front to back on the surface. During the movement of the cleaning head, the wet tissue always fits with the surface of the cultural relic;

[0080] (5) Then remove the cleaning head, take off the wet tissue, and use an X-ray fluorescence spectrometer to test and analyze the elemental content of the pollutants on the surface of the cultural relic. After analysis, it is considered that the pollutants have been cleaned, and the surface cleaning of the simulated aged and contaminated sample is completed.

[0081] Comparative Example 3 (simulated aged and contaminated sample that can replace leather cultural relics, slightly aged)

[0082] The difference from Example 2 is that: the thickness of the chitosan non-woven fabric in step 2 is 1.5 mm.

[0083] The surface cleaning method for leather cultural relics includes the following steps:

[0084] (1) Add 0.1 g of water-soluble lanolin, 0.03 g of saponin, 0.2 g of phospholipid, and 0.5 g of Bacillus licheniformis protease to a 20 mL mixture of ethanol and water with a mass ratio of 1:4 at room temperature to obtain a cleaning solution;

[0085] (2) Add 0.2 g of gelatin, 0.2 g of sodium alginate, and 0.3 g of glycerol to 20 mL of water at room temperature to obtain a treatment solution. Then immerse a chitosan non-woven fabric with a thickness of 1.5 mm in the treatment solution for 60 min. After taking it out, hang it until no water drops, and obtain a hydrogel adsorption wet tissue;

[0086] (3) Dip a cotton swab in the cleaning solution to moisten the simulated aged and contaminated sample, and place a layer of the above gel adsorption wet tissue on its surface; (4) Fix the four sides of the gel adsorption wet tissue, turn on the cleaning device, set the ultrasonic frequency to 80 kHz, and the negative pressure to 0.2 kPa; Press the cleaning head on the device tightly against the wet tissue, place the ultrasonic transducer before the negative pressure adsorption tube, and slowly move the cleaning head from front to back on the surface. During the movement of the cleaning head, the wet tissue always fits with the surface of the cultural relic;

[0087] (5) Then, the cleaning head was removed, the wet tissue was taken off, and the content of pollutant elements on the surface of the cultural relics was tested and analyzed using an X-ray fluorescence spectrometer (higher than that in Example 2). After analysis, it was found that the pollutants were not completely cleaned and there were still a lot of pollutants remaining.

[0088] Comparative Example 4 (Simulated aging contaminated samples and slight aging that can replace leather artifacts)

[0089] The difference from Example 2 is that the water-soluble lanolin in step 1 is 1 g and the phospholipid is 1 g.

[0090] The surface cleaning method of leather cultural relics includes the following steps:

[0091] (1) adding 1 g of water-soluble lanolin, 0.03 g of tea saponin, 1 g of phospholipid, and 0.5 g of Bacillus licheniformis protease to a mixture of 20 mL of ethanol and water in a mass ratio of 1:4 at room temperature to obtain a cleaning solution;

[0092] (2) adding 0.2 g of gelatin, 0.2 g of sodium alginate, and 0.3 g of glycerol to 20 mL of water at room temperature to obtain a treatment solution, and then immersing a chitosan non-woven fabric with a thickness of 0.1 mm in the treatment solution for 60 min, taking it out and hanging it until no water drops fall, to obtain a hydrogel adsorbed wet tissue;

[0093] (3) Use a cotton swab to dip into the cleaning solution to wet the simulated aging contaminated sample, and place a layer of the above-mentioned gel-absorbed wet paper towel on its surface; (4) Fix the four sides of the gel-absorbed wet paper towel, turn on the cleaning device, set the ultrasonic frequency to 80kHz, and the negative pressure to 0.2kPa; place the cleaning head on the device close to the wet paper towel, place the ultrasonic transducer in front of the negative pressure adsorption tube and slowly move the cleaning head from front to back on the surface. During the movement of the cleaning head, the wet paper towel always adheres to the surface of the cultural relic;

[0094] (5) Then, the cleaning head was removed, the wet tissue was taken off, and the content of pollutant elements on the surface of the cultural relics was tested and analyzed using an X-ray fluorescence spectrometer (higher than that in Example 2). After analysis, it was found that the pollutants were not completely cleaned and there were still a lot of pollutants remaining.

[0095] Comparative Example 5 (Simulated aging contaminated samples and severe aging samples that can replace leather artifacts)

[0096] The difference from Example 2 is that the simulated aged contaminated sample is prepared by the same method, but it is severely aged.

[0097] The surface cleaning method of leather cultural relics includes the following steps:

[0098] (1) Add 0.1 g of water-soluble lanolin, 0.03 g of tea saponin, 0.2 g of phospholipid, and 0.5 g of Bacillus licheniformis protease to 20 mL of a mixed solution of ethanol and water with a mass ratio of 1:4 at room temperature to obtain a cleaning solution;

[0099] (2) Add 0.2 g of gelatin, 0.2 g of sodium alginate, and 0.3 g of glycerol to 20 mL of water at room temperature to obtain a treatment solution. Then immerse a chitosan non-woven fabric with a thickness of 0.1 mm in the treatment solution for 60 min, take it out and hang it until no water drops, to obtain a hydrogel adsorption wet tissue;

[0100] (3) Dip a cotton swab in the cleaning solution to moisten the simulated aged pollution sample, and place a layer of the above gel adsorption wet tissue on its surface; (4) Fix the four sides of the gel adsorption wet tissue, turn on the cleaning device, set the ultrasonic frequency to 80 kHz and the negative pressure to 0.2 kPa; Press the cleaning head on the device tightly against the wet tissue, place the ultrasonic transducer in front of the negative pressure adsorption tube and move the cleaning head slowly from front to back on the surface. During the movement of the cleaning head, the wet tissue always fits with the surface of the cultural relic;

[0101] (5) Then remove the cleaning head, take off the wet tissue, and use an X-ray fluorescence spectrometer to detect the residual amount of pollutant elements in the simulated sample after the cleaning head moves. The test results show that there are still residues of pollutants, but the simulated sample has been damaged and decomposed and cannot be further cleaned on the surface.

[0102] Analyze and test the cultural relic fragments and simulated samples in the examples and comparative examples. The equipment used is as follows: Use an infrared spectrometer (Nicolet 6700 type, Thermo Nicolet Corporation, USA) to perform infrared spectroscopy tests on the gel polymer; Use a scanning electron microscope (Sigma300, Carl Zeiss, Germany) and a three-dimensional video microscope (VH X-2000, Keyence, Japan) to take microscopic images of leather cultural relics and simulated samples; Use a portable X-ray fluorescence spectrometer (ThermoFisher NITON XL3t950-HE, Thermo Nicolet Corporation, USA) to test the residual amount of pollutant elements.

[0103] As Figure 2 shown is the infrared spectrogram of the gel polymer and raw materials in the hydrogel adsorption wet tissue paper. Comparing the infrared spectrograms of the three raw materials of chitosan, sodium alginate, and gelatin, the infrared spectrum of the gel in the wet tissue paper in the present invention is enhanced at 2885 cm -1 , and its absorption peak is the stretching vibration of C-H, indicating the formation of a polymer; It weakens at 1650 cm -1 and 1420 cm -1 , while it strengthens at 1590 cm -1 and 1156 cm -1The intensity at 854 cm-1 is stronger, indicating that the amide bond -CO-NH- in chitosan is broken, a COC bond is generated, and an acid salt ion pair is formed by hydrogen bonding. -1 There is a newly generated absorption vibration peak at 1085cm, which is the glycosidic bond formed by the hemiacetal hydroxyl group in chitosan and the hydroxyl and amino groups in gelatin and sodium alginate. At the same time, the gelatin at 1085cm -1 1034cm -1 The infrared spectrum of the gel in the wet tissue paper shows that through the preparation method of the present invention, chitosan non-woven fabric, gelatin, sodium alginate, and glycerol (which plays a moisturizing role and does not participate in the polymerization reaction) can be used to generate hydrogel material in the wet tissue paper through polymerization reaction, which plays the role of adhesion and moisturizing.

[0104] like Figure 3 Shown are leather artifact fragments unearthed in Inner Mongolia and microscopic images of three different areas before and after cleaning. Figure 3 (a) is a digital image of an unearthed leather artifact fragment, which is divided into three different areas. Area 1 is the clean area of ​​Example 1, Area 2 is the clean area of ​​Comparative Example 1, and Area 3 is the clean area of ​​Comparative Example 2. Figure 3 (b) is a digital image of the entire debris after cleaning in three different areas by Example 1, Comparative Example 1, and Comparative Example 2. It can be seen that the cleaning effect of area 1 is better than that of the other two areas, and there is no obvious black contaminant on the surface. Figure 3 (c) shows a microscopic image of the uncleaned fragment, which shows a large amount of contaminants on the surface, appearing as black blocky grease contaminants that adhere closely to the surface. Figure 3 In the microscopic image of the debris area (d) after cleaning, it can be seen that there is no obvious black contamination on the surface, and it has a certain glossiness and no cracks. Figure 3 (e) is a microscopic image of the debris area 2 after cleaning. Since chitosan non-woven fabric was not used, hydrogel polymers could not be generated during the immersion process in the mixed solution of gelatin, sodium alginate and glycerol, and the adsorption and bonding effect could not be achieved. From the microscopic image, it can be seen that certain pollutants are still present. Figure 3 (f) is a microscopic image of the debris area 3 after cleaning, indicating that negative pressure adsorption alone cannot clean all pollutants. Only cleaning fluid without the assistance of ultrasound can separate a small amount of pollutants from the collagen fibers, and all pollutants cannot be cleaned.

[0105] like Figure 4 Shown are the results of X-ray fluorescence spectrum analysis of unearthed leather artifact fragments and three different areas before and after cleaning. The number of electron counts on the vertical axis in the figure reflects the amount of element content. Figure 4(a) is the X-ray fluorescence spectrum of the debris before cleaning. The results show that the contents of Ca and Fe elements are relatively high, which should be the chelates of mineral pollutants and collagen fibers. The electron count of Ca element reaches 39.1 and that of Fe element reaches 33.5. Figure 4 (b) is the X-ray fluorescence spectrum of area 1 of the debris after cleaning in Example 1. The electron count of Ca element reaches 16.1 and that of Fe element reaches 9.15. Figure 4 (c) is the X-ray fluorescence spectrum of area 2 of the debris after cleaning in Comparative Example 1. The electron count of Ca element reaches 22.5 and that of Fe element reaches 22.6. Figure 4 (d) is the X-ray fluorescence spectrum of area 3 of the debris after cleaning in Comparative Example 2. The electron count of Ca element reaches 25.2 and that of Fe element reaches 26.7. From the comparative analysis of the counts of Ca and Fe elements in the X-ray fluorescence spectrum, it can be seen that the cleaning effect of Example 1 is the best, and it can better remove the chelates of mineral pollutants.

[0106] As Figure 5 shown are the energy spectrum diagrams of elements before and after cleaning of the simulated samples of leather cultural relics cleaned with different reagent formulations. Figure 5 (a) is the energy spectrum diagram of elements before cleaning of the simulated sample of leather cultural relics. The pollutants are mainly common compounds in the simulated burial environment of cultural relics. For example, the Si element represents soil particles, and the Fe, Ca, Al, and K elements represent various minerals and some chelates of their chelation with collagen. The Cl element represents salts or chlorides, which can cause salting out or protein dissolution of collagen. If these pollutants are not cleaned in time, they will cause degradation of the leather over time, resulting in fractures, damages, and decay. Figure 5 (b) is the energy spectrum diagram of elements after cleaning the simulated sample of leather cultural relics according to Example 2. Figure 5 (c) is the energy spectrum diagram of elements after cleaning the simulated sample of leather cultural relics according to Comparative Example 3. Figure 5 (d) is the energy spectrum diagram of elements after cleaning the simulated sample of leather cultural relics according to Comparative Example 4. Figure 5 (e) is the energy spectrum diagram of elements after cleaning the simulated sample of leather cultural relics according to Comparative Example 5. Through comparison, it is found that the cleaning effect of Example 2 is the most obvious, and the proportion of the main pollutant element components has decreased significantly, indicating that the compounds containing Si, K, Fe, Al, Ca, etc. in the pollutants can be significantly cleaned, and the main pollutants in the original simulated sample of leather cultural relics can be effectively removed.

[0107] As Figure 6 shown are the microscopic images of leather cultural relics with different aging degrees. Figure 6 (a) is the microscopic image of the leather after slight aging, and there are no cracks on the surface. Figure 6 (b) is the microscopic image of the moderately aged leather, and there are a small number of cracks on the surface, and no exfoliated particles. Figure 6(c) is a microscopic image of severely aged leather, with a large number of cracks and exfoliated particles on the surface. The aging degree of cultural relics can be judged first through microscopic images, and then a suitable cleaning method can be selected.

[0108] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent transformations made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for surface cleaning of leather cultural relics, characterized in that, it comprises the following steps: (1) Add water-soluble lanolin, tea saponin, phospholipid, and bacillus licheniformis protease into an ethanol aqueous solution at room temperature and mix to obtain a cleaning solution; add gelatin, sodium alginate, and glycerol into water at room temperature to obtain a treatment solution; then soak a chitosan non-woven fabric in the treatment solution for no less than 30 minutes, take it out and hang it until no water drips, and encapsulate it to keep it from drying to obtain a hydrogel adsorption wet tissue; moisten the surface of the leather cultural relics to be cleaned with the cleaning solution, and then place the hydrogel adsorption wet tissue on the surface; (2) Fix the four sides of the hydrogel adsorption wet tissue, and simultaneously perform ultrasonic and negative pressure adsorption on its surface; the frequency of the ultrasonic wave is 20 - 80 kHz; the intensity of the negative pressure adsorption is 0 - 0.2 kPa; (3) Then remove the hydrogel adsorption wet tissue to complete the surface cleaning of the leather cultural relics.

2. The method for surface cleaning of leather cultural relics according to claim 1, characterized in that, the mass-volume ratio of the water-soluble lanolin, tea saponin, phospholipid, bacillus licheniformis protease, and the ethanol aqueous solution is 0.1 - 0.5 g : 0.01 - 0.05 g : 0.1 - 0.5 g : 0.1 - 0.5 g : 20 mL; the mass ratio of ethanol to water in the ethanol aqueous solution is 1 : 2 - 10.

3. The method for surface cleaning of leather cultural relics according to claim 1, characterized in that, the mass-volume ratio of the gelatin, sodium alginate, glycerol, and water is 0.1 - 0.5 g : 0.1 - 0.5 g : 0.1 - 0.5 g : 20 mL; the thickness of the chitosan non-woven fabric does not exceed 1 mm.

4. The method for surface cleaning of leather cultural relics according to claim 1, characterized in that, the thickness of the hydrogel adsorption wet tissue does not exceed 1 mm.

5. The method for surface cleaning of leather cultural relics according to claim 1, characterized in that, the cleaning device used in the cleaning method comprises a power regulator (2) and a cleaning head (1) connected to the power regulator (2) and placed outside the power regulator (2); the power regulator (2) comprises an ultrasonic generator (7) and a negative pressure vacuum pump (9) arranged inside it; the cleaning head (1) comprises an ultrasonic transducer (4) and a negative pressure adsorption tube (5); the ultrasonic transducer (4) is connected to the ultrasonic generator (7); the negative pressure adsorption tube (5) is connected to the negative pressure vacuum pump (9).

6. The method for surface cleaning of leather cultural relics according to claim 5, characterized in that, the ultrasonic transducer (4) and the negative pressure adsorption tube (5) in the cleaning head (1) are fixed, and when acting on the surface of the hydrogel adsorption wet tissue, the ultrasonic transducer (4) is placed in front of the negative pressure adsorption tube (5) and the cleaning head is moved from front to back on the surface.

7. The method for surface cleaning of leather cultural relics according to claim 5, characterized in that, The power regulator (2) further includes an acoustic power regulator (8) and a negative pressure regulator (10) disposed outside thereof; the acoustic power regulator (8) is connected to the ultrasonic generator (7); the negative pressure regulator (10) is connected to the negative pressure vacuum pump (9).

8. The surface cleaning method of leather cultural relics according to claim 7, wherein, the acoustic power regulator (8) has three-stage acoustic wave frequency regulation of 20 kHz, 40 kHz, and 80 kHz; the negative pressure regulator (10) has negative pressure suction intensity regulation in the range of 0 to 0.2 kPa.

9. The surface cleaning method of leather cultural relics according to claim 7 or 8, wherein, the cleaning device further includes a recovery pool (3) connected to the power regulator (2) and disposed outside the power regulator (2); the ultrasonic transducer (4) is connected to the ultrasonic generator (7) through a power cord (6).

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