PAM / PVA hydrogel for removing animal glue layer in cultural heritage protection and preparation method of PAM / PVA hydrogel

Abstract

The invention relates to the technical field of high polymer materials, in particular to PAM / PVA hydrogel for removing an animal glue layer in cultural heritage protection and a preparation method of the PAM / PVA hydrogel. The preparation method comprises the following steps: mixing an acrylamide monomer solution, a polyvinyl alcohol solution and a cross-linking agent solution to obtain a hydrogel precursor; and mixing the hydrogel precursor, an initiator solution and a catalyst solution, and carrying out polymerization and curing to obtain the hydrogel. A hydrogel network is induced to generate microstructure phase change from a disordered amorphous state to a highly ordered crystalline state by regulating and controlling the critical concentration of an acrylamide monomer, the obtained hydrogel shows an anti-conventional storage modulus (G ') thermotropic enhancement characteristic at the working temperature of 45 DEG C, and the loss tangent (tan delta) is as low as 0.10; meanwhile, the water retention capacity is excellent (the water loss rate in 60 minutes is only 21%). The hydrogel can be used for carrying out controllable softening and residue-free removal on aged animal glue layers on the surfaces of ancient books, paintings and furniture under a heating condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, and particularly relates to PAM / PVA hydrogel for removing animal glue layer in cultural heritage protection and a preparation method thereof. BACKGROUND

[0002] In the field of cultural heritage protection and restoration, animal glue (such as bone glue, skin glue, swim bladder glue, etc.) is the most common bonding material in ancient paintings, books and furniture. However, over time, the aged animal glue layer will crack, mold or hinder the further restoration of cultural relics, so "degluing" is a key process in the restoration of cultural relics. Traditional degluing methods include mechanical removal and wet dressing. The mechanical method is easy to damage the fragile cultural relics; the wet dressing method (such as using a cotton ball soaked in hot water) is difficult to accurately control the moisture, which is easy to cause water stain diffusion, paper wrinkling or wood deformation. In recent years, hydrogel has been introduced as a new generation of cleaning tool due to its controllable solvent release characteristics.

[0003] Although hydrogel performs well in normal temperature cleaning, it is usually necessary to raise the operating temperature to about 45℃ when removing stubborn aged animal glue (this temperature can effectively soften the glue layer and is within the safety threshold of cultural relics). However, the conventional hydrogel in the prior art cannot adapt to this specific working condition, and there is a serious "thermal failure" problem: Structural collapse (soften): as the temperature rises to 45℃, the thermal motion of the conventional polymer network intensifies, leading to a sharp decay of the storage modulus (G'). When dealing with delicate cultural relics (such as ancient paintings), the over-softened gel cannot provide sufficient mechanical support and is easy to be extruded and deformed under operating pressure, damaging the painting core.

[0004] Residual risk (sticky): more fatally, high temperature will cause the physical interaction (such as hydrogen bond) in the gel network to dissociate, causing an unfavorable transition in its viscoelasticity - the loss tangent (tanδ) increases significantly. This means that the gel exhibits more "liquid" properties and the viscosity increases. When trying to remove the gel from the rough surface of cultural relics (such as fiber-interlaced paper or porous wood), high viscosity is extremely easy to cause cohesive failure of the gel, resulting in stringing, breaking and leaving polymer residues on the surface of cultural relics, forming irreversible "secondary pollution".

[0005] In summary, there is an urgent need in the art for a cleaning hydrogel designed for the 45℃ temperature zone, which needs to maintain high structural stiffness (high G') and extremely low viscosity loss (low tanδ) in the heated state, in order to achieve the perfect unity of "hot compress softening" and "residue-free removal". SUMMARY

[0006] The present application aims to provide a PAM / PVA hydrogel for removing animal glue layer in cultural heritage protection and a preparation method thereof, so as to solve the technical problems of structural instability, high residual risk and solvent out-of-control of the existing hydrogel under the 45 DEG C cultural relic cleaning condition.

[0007] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions. One of the technical solutions of the present application is a preparation method of a hydrogel for removing animal glue layer, comprising the following steps: (1) mixing an acrylamide monomer solution, a polyvinyl alcohol solution and a crosslinking agent solution to obtain a hydrogel precursor; (2) mixing the hydrogel precursor, an initiator solution and a catalyst solution, polymerizing, and solidifying to obtain the hydrogel for removing animal glue layer.

[0008] The second technical solution of the present application is the hydrogel for removing animal glue layer prepared by the above-mentioned preparation method of the hydrogel for removing animal glue layer.

[0009] The third technical solution of the present application is an application of the above-mentioned hydrogel for removing animal glue layer as a cleaning tool in the field of cultural heritage protection, and the application objects include the back glue of ancient books, the glue layer or backing paper of painting works, and the mortise and tenon joint or surface glue stain of wooden furniture.

[0010] Compared with the prior art, the present application has the following beneficial effects: 1. The hydrogel prepared by the present application has a continuously enhanced G' at 45 DEG C, which ensures that the hydrogel maintains its physical form during long-time heating operation and ensures the controllability of the operation.

[0011] 2. The hydrogel prepared by the present application has a minimum tan delta (0.10) at 45 DEG C, which presents ideal elasticity, and the ideal elasticity makes it easy to be removed from the surface of cultural relics in a complete and clean manner.

[0012] 3. The hydrogel prepared by the present application has the strongest water retention capacity (water loss rate 21%) at 45 DEG C, which ensures that the hydrogel can act as a stable solvent pool to continuously and controllably soften the animal glue layer during heating.

[0013] 4. The hydrogel prepared by the present application is suitable for high-demand fine cultural relic cleaning applications, and in particular, it can controllably and residue-free remove the animal glue layer at 45 DEG C. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The Fourier transform infrared spectrum (FTIR) comparison chart of the hydrogels of Examples 1-3; Figure 2 The water loss kinetics curve of the hydrogel of Example 1-5 at 45 DEG C; Figure 3 Comparison chart of tensile properties of hydrogels of Examples 1-5; Figure 4 Comparison chart of dynamic stability of hydrogels of Examples 1-5 at constant temperature of 45℃, wherein (a) is storage modulus (G') change with time; (b) is loss tangent (tan δ) change with time; Figure 5 Animal glue removal application effect chart of hydrogel of Example 1. DETAILED DESCRIPTION

[0015] The various illustrative embodiments of the present application will now be described in detail below. This description is not intended to be a limitation on the present application but rather a description of certain embodiments of the present application, and thus should not be used to interpret or limit the scope or spirit of the present application.

[0016] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. In addition, where particular ranges of values are given, understand that each intervening value, to the upper or lower limit of the ranges is also specifically included. Each smaller range that falls within the broader ranges is also specifically included. The upper and lower limits of these smaller ranges can independently be included or excluded in the range, and each range of values should be considered as having been specifically stated.

[0017] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict, the content of the present specification will control.

[0018] Various modifications and changes can be made to the specific embodiments of the present application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples presented herein. The specification and examples given should be considered exemplary only, with the true scope and spirit of the application indicated by the following claims.

[0019] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean including, but not limited to.

[0020] The raw materials used in the present application can be obtained commercially or prepared by prior art.

[0021] The present application provides a preparation method of a hydrogel for removing animal glue layer, comprising the following steps: (1) mixing acrylamide monomer solution, polyvinyl alcohol solution and crosslinking agent solution to obtain hydrogel precursor; (2) mixing hydrogel precursor, initiator solution and catalyst solution, polymerizing, solidifying to obtain hydrogel with animal glue layer removed.

[0022] In the application, a precursor solution containing polyvinyl alcohol (PVA) and acrylamide (AM) monomer is provided first; then the polymerization of the precursor solution is initiated; the core is that the concentration of the AM monomer is set to a critical optimized value to induce the microstructure phase transition of the hydrogel network from disordered amorphous state to highly ordered crystalline state, so that the prepared hydrogel can remove the animal glue layer at 45℃.

[0023] In the application, the concentration of the acrylamide monomer solution is 5-30wt%, for example, it can be 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt% and the like; the concentration of the polyvinyl alcohol solution is 5-20wt%, for example, it can be 5wt%, 10wt%, 15wt% or 20wt% and the like; the mass ratio of acrylamide monomer and polyvinyl alcohol is 1:0.05-0.25, for example, it can be 0.05, 0.1, 0.15, 0.2 or 0.25 and the like.

[0024] In the application, the concentration of the AM monomer is set to an optimized value (for example, in a system of 6g 10wt% PVA solution, the amount of AM is 4g), which is higher than a first threshold value (for example, 3g) resulting in a network in disordered amorphous state, and lower than a second threshold value (for example, 5g) resulting in tanδ greater than 0.15 at 45℃.

[0025] In the application, the crosslinking agent solution includes N,N'-methylene bisacrylamide solution; the volume concentration of the crosslinking agent solution is 2.5%; the amount ratio of the polyvinyl alcohol solution and the crosslinking agent solution is 2-10g:1-3mL, for example, it can be 2g:1mL, 3g:1mL, 4g:1mL, 6g:1mL, 8g:1mL or 10g:1mL and the like.

[0026] In the application, the temperature for mixing in step (1) is 40-70℃, for example, it can be 40℃, 50℃, 55℃, 60℃ or 70℃ and the like.

[0027] In the application, the initiator solution includes potassium persulfate solution; the concentration of the initiator solution is 12wt%; the volume ratio of the initiator solution and the crosslinking agent solution is 1:0.3-6, for example, it can be 1:0.3, 1:0.5, 1:1, 1:2, 1:3, 1:5 or 1:6 and the like.

[0028] In the present application, the catalyst solution is N,N,N',N'-tetramethyl ethylenediamine solution; the concentration of the catalyst solution is 12 vol%; the volume ratio of the catalyst solution and the crosslinking agent solution is 1:1~30, for example, it can be 1:1, 1:4, 1:5, 1:8, 1:10, 1:15, 1:20, 1:25 or 1:30, etc.

[0029] In the present application, the temperature of polymerization in step (2) is 50℃, and the time is 5 min; the temperature of solidification is 50℃, and the time is 5~30 min, for example, it can be 5 min, 10 min, 15 min, 20 min, 25 min or 30 min, etc.

[0030] It can be understood that, under the premise of realizing the core inventive concept (inducing microstructure phase transition through critical AM monomer concentration to obtain "low tan delta"), the process parameters such as the amount of MBA, PVA, KPS and TEMED can be reasonably selected within the above-mentioned limited range.

[0031] The present application also provides the animal glue layer-removed hydrogel prepared by the preparation method of the animal glue layer-removed hydrogel.

[0032] It can be understood that, the present application provides a PAM / PVA double network hydrogel with controllable removal of animal glue layer in cultural heritage protection, high toughness and high dynamic stability.

[0033] In the present application, the animal glue layer-removed hydrogel has a loss tangent (tan delta) lower than 0.10 within 30 min of testing time when performing dynamic mechanical analysis (DMA) test at a constant temperature of 45℃ and a frequency of 1 Hz; and a storage modulus (G') greater than 20 kPa, and no decay or showing an enhancement trend within 30 min of testing time.

[0034] In the present application, the animal glue layer-removed hydrogel has a highly ordered crystalline microstructure, which shows a series of sharp and well-separated absorption peaks in the fingerprint region (1500~900 cm -1 ) of Fourier transform infrared spectroscopy (FTIR).

[0035] In the present application, the hydrogel has a water loss rate lower than 25% within 60 min of testing time when performing water loss kinetics test at 45℃, preferably 21%.

[0036] The present application also provides the application of the above-mentioned animal glue layer-removed hydrogel as a cleaning tool in the field of cultural heritage protection, such as the glue layer or backing paper of the spine of ancient books, the glue layer of painting works, the mortise and tenon joint or surface glue stain of wooden furniture.

[0037] In the present application, the application method comprises: covering the hydrogel on the area to be cleaned, keeping contact at 45-50℃ until the isinglass layer softens, and then using the hydrogel with a loss tangent (tan δ) of less than 0.10 in the heated state to completely strip the hydrogel together with the adsorbed softened isinglass layer from the surface of the application object.

[0038] The working temperature of the hydrogel for removing the isinglass layer is 45℃, the high and stable storage modulus (G') of the hydrogel enables it to maintain structural integrity without collapsing at the working temperature; the low loss tangent (tan δ) of the hydrogel enables it to have ideal elasticity, ensuring that it can be completely removed after operation, reducing the risk of residue.

[0039] It can be understood that there is a non-monotonic relationship between the AM monomer concentration and the key application performance (tan δ and water retention) of the material at 45℃. The creativity of the present application lies in breaking the conventional technical prejudice that "the higher the concentration, the better", and accidentally discovering that the concentration of AM can induce a microstructure phase transition (from disordered amorphous state to highly ordered crystalline state) within a specific and narrow optimization window of AM concentration.

[0040] The technical solutions provided by the present application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application.

[0041] Preparation Example (1) Disperse polyvinyl alcohol (PVA) in water, dissolve at 90℃ to obtain a PVA stock solution with a concentration of 10wt%; (2) Disperse potassium persulfate (KPS) in water, mix uniformly to obtain a KPS stock solution with a concentration of 12wt%; (3) Disperse N,N,N',N'-tetramethyl ethylenediamine (TEMED) in water, mix uniformly to obtain a TEMED stock solution with a concentration of 12vol%; (4) Disperse N,N'-methylene bisacrylamide (MBA) in water, mix uniformly to obtain an MBA stock solution with a volume concentration of 2.5%.

[0042] Example 1 (1) Dissolve 4g of acrylamide (AM) monomer in 10mL of deionized water at 50℃, then add 6g of PVA solution with a concentration of 10wt%, and then add 2mL of MBA crosslinking agent solution with a volume concentration of 2.5%, keep the temperature of the mixed system at 55℃ to obtain a precursor solution; (2) To the precursor solution, 1 mL of KPS solution with a concentration of 12 wt% and 0.5 mL of TEMED solution with a concentration of 12 vol% were added, and after the system began to thicken at 50°C for 5 min, it was poured into a mold, and cured at 50°C for 20 min to form a gel, which was recorded as AM-4.

[0043] Example 2 The difference from Example 1 is only that the amount of acrylamide (AM) monomer added is 3 g, and the obtained hydrogel is recorded as AM-3.

[0044] Example 3 The difference from Example 1 is only that the amount of acrylamide (AM) monomer added is 5 g, and the obtained hydrogel is recorded as AM-5.

[0045] Example 4 The difference from Example 1 is only that the amount of acrylamide (AM) monomer added is 1 g, and the obtained hydrogel is recorded as AM-1.

[0046] Example 5 The difference from Example 1 is only that the amount of acrylamide (AM) monomer added is 2 g, and the obtained hydrogel is recorded as AM-2.

[0047] Figure 1 The Fourier transform infrared spectrum (FTIR) comparison chart of Examples 1-3 of the present application is shown in Figure 1 It can be seen that the FTIR spectrum of Example 2 (AM-3) is smooth in the fingerprint region, showing a disordered amorphous state. The hydrogel of Example 1 (AM-4) has a highly ordered crystalline microstructure, which shows a series of sharp and well-separated absorption peaks in the fingerprint region (1500-900 cm -1 ) of the Fourier transform infrared spectrum (FTIR), and Example 3 (AM-5) also shows sharp crystalline peaks, confirming that a microstructure phase transition occurs from AM-3 to AM-4.

[0048] Figure 2 The 45°C water loss kinetics curve of the hydrogels prepared in Examples 1-5 of the present application is shown in Figure 2 It can be seen that the water loss rate of Example 3 (AM-5) is the fastest (51% water loss in 60 min), and the "solvent out of control" problem in the background art has not been solved. The water loss rate of Example 1 (AM-4) is the lowest (21% water loss in 60 min), and the solvent supply is the most controllable.

[0049] Figure 3 The tensile property comparison chart of the hydrogels prepared in Examples 1-5 of the present application is shown in Figure 3It can be seen that the breaking strain (250%) of Example 3 (AM-5) is much lower than that of Example 1 (AM-4) (350%) of the present application, indicating that the present application solves the problem of brittleness caused by excessive crystallization.

[0050] The hydrogel was subjected to dynamic mechanical analysis (DMA) test at 45°C constant temperature and 1 Hz frequency: Figure 4 The dynamic stability comparison chart of the hydrogel prepared for Examples 1-5 of the present application at 45°C constant temperature, Figure 4 (a) is the change of storage modulus (G') with time, the G' of Example 2 (AM-3, amorphous) significantly decays (about 19%) at 45°C, and the dynamic stability is the worst, which fails to solve the "structural instability" problem in the background art; Figure 4 (b) is the change of loss tangent (tan δ) with time, the tan δ value of Example 3 (AM-5, excessive crystallization) is the highest (0.19), the energy loss is extremely large, and there is a high risk of residue, which fails to solve the "residue risk" problem in the background art; while the G' of Example 1 (AM-4) does not decay and continuously increases (about 19→21 kPa) within 30 minutes of testing time, and the low tan δ value is the lowest (0.10) within 30 minutes of testing time, showing ideal elasticity and the lowest residue risk. This embodiment simultaneously solves the above two technical problems.

[0051] Simulation experiment: fluorescent animal glue removal experiment Preparation of fluorescent animal glue substrate: To simulate the glue layer on cultural products, animal glue particles (10 g) were dissolved in 90 mL deionized water (60°C water bath) and doped with europium nitrate (Eu(NO3)3) solution as a fluorescent marker. A doctor blade coater was used to uniformly coat the fluorescent glue solution on a 10 cm × 10 cm filter paper to prepare a simulated substrate with a thickness of 10 μm and 20 μm, respectively. All samples were dried at 25°C for 24 hours to ensure complete curing of the glue layer.

[0052] Animal glue removal and quantitative monitoring: PAM / PVA hydrogel samples (5 cm × 5 cm × 5 mm) were cut and covered on the surface of the fluorescent animal glue substrate. A 150 W infrared heating lamp (distance 10 cm) was used to heat the hydrogel, and the surface temperature was controlled at 45°C. At the preset time point, the hydrogel was removed, and the emission spectrum of the substrate was immediately recorded using a fluorescence spectrophotometer. The removal effect was quantitatively evaluated by monitoring the decay of the fluorescence characteristic peak intensity over time.

[0053] Figure 5 The animal glue removal application effect chart for Example 1 (AM-4) of the present application, Figure 5It can be seen that the example 1 (AM-4) can efficiently and controllably remove the animal glue layer. This successful application is due to the fact that the example 1 (AM-4) has both the structural stability lacking in the comparative example 1 (AM-3) and the ideal elasticity (low tan delta) and water retention capacity lacking in the comparative example 2 (AM-5) at 45 DEG C.

[0054] Application example 1: Removing the spine back glue of ancient books For the repair of a reprinted Qing Dynasty book, the hardened and brittle bone glue layer on the spine needs to be removed.

[0055] Operation steps: The hydrogel (AM-4) prepared in the example 1 of the present application is cut into a long strip with a width of 2 cm and a length of 20 cm. The hydrogel is preheated using an infrared lamp and maintained at 45 DEG C, and is tightly attached to the surface of the spine back glue.

[0056] Effect evaluation: After wetting for 20 minutes at 45 DEG C, the bone glue layer is fully swollen and softened due to the high water retention of the hydrogel (the water loss rate is only about 7%), and the water does not diffuse to the deep layer of the book page (no water stain ring). Subsequently, the removal operation is performed. Since the tan delta of the AM-4 hydrogel is as low as 0.10 at 45 DEG C, it exhibits excellent rubber elasticity, and the operator can tear it off in its entirety. Microscopic observation shows that the softened bone glue is adhered and taken away by the gel, and there is no gel residue on the surface fibers of the spine paper, and no paper damage occurs.

[0057] Application example 2: Removing the old backing paper of a painting For a reprinted colored paper national painting, the back of the old leather paper is pasted with animal glue, and the old leather paper needs to be contacted.

[0058] Operation steps: The AM-4 hydrogel and the AM-3 hydrogel are respectively prepared into 2 mm thick sheets, and are covered on the local old leather paper on the back of the painting core. Under the condition of 45 DEG C temperature control, the action is performed for 15 minutes.

[0059] Effect evaluation: Compared with the comparative example (AM-3), the storage modulus G' of the AM-4 hydrogel continuously increases (> 20 kPa) during the heating process, and always maintains a crisp solid form. This high stiffness characteristic avoids the rheological deformation of the gel when pressed, and prevents the gel from being trapped in the gap between the paper fibers. After the softening is completed, the old leather paper is easily separated from the painting core, and the cross section is smooth when the gel is removed, without adhesion and fiber pulling phenomenon, which ensures the safety of the fragile painting core.

[0060] Application example 3: Cleaning the tenon and mortise glue stains of furniture For a thick layer of roe glue remaining at the tenon and mortise interface of a purple sand furniture.

[0061] Operation steps: cut AM-4 hydrogel and AM-5 hydrogel into blocks respectively, fill into the mortise and tenon gap respectively, and heat to 45℃ area with the aid of infrared lamp.

[0062] Effect evaluation: the wood surface is rough and porous, which is the most common gel residue substrate. The conventional gel (AM-5) is extremely easy to break and crack when taken out of the wood gap after heating due to excessive crystallization and high tan delta. The AM-4 hydrogel of the present application has high toughness (elongation at break 350%) and low viscosity, and can be pulled out as a whole after softening the air sac glue, without any polymer residue on the wood surface, achieving perfect non-destructive cleaning of the complex structure surface.

[0063] In summary, the above different embodiments strongly prove that the unexpected technical effects of "low tan delta" and the like can be obtained by inducing microstructure phase transition through critical AM monomer concentration (preferably 4g).

[0064] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled persons in the art, without departing from the principle of the present application (i.e. inducing microstructure phase transition by critical AM concentration), several improvements and refinements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a hydrogel with an animal glue layer removed, characterized in that, Includes the following steps: (1) Mix the acrylamide monomer solution, polyvinyl alcohol solution, and crosslinking agent solution to obtain the hydrogel precursor; (2) The hydrogel precursor, initiator solution and catalyst solution are mixed, polymerized and solidified to obtain a hydrogel with the animal glue layer removed.

2. The method for preparing the hydrogel with the animal glue layer removed according to claim 1, characterized in that, The concentration of the acrylamide monomer solution is 5-30 wt%; the concentration of the polyvinyl alcohol solution is 5-20 wt%; and the mass ratio of acrylamide monomer to polyvinyl alcohol is 1:0.05-0.

25.

3. The method for preparing the hydrogel with the animal glue layer removed according to claim 1, characterized in that, The crosslinking agent solution includes an N,N'-methylenebisacrylamide solution; the volume concentration of the crosslinking agent solution is 2.5%; the ratio of the amount of polyvinyl alcohol solution to the amount of crosslinking agent solution is 2~10g:1~3mL.

4. The method for preparing a hydrogel with the animal glue layer removed according to claim 1, characterized in that, The mixing temperature in step (1) is 40~70℃.

5. The method for preparing a hydrogel with the animal glue layer removed according to claim 1, characterized in that, The initiator solution includes a potassium persulfate solution; the concentration of the initiator solution is 12 wt%; and the volume ratio of the initiator solution to the crosslinking agent solution is 1:0.3~6.

6. The method for preparing a hydrogel with the animal glue layer removed according to claim 1, characterized in that, The catalyst solution is an N,N,N',N'-tetramethylethylenediamine solution; the concentration of the catalyst solution is 12 vol%; and the volume ratio of the catalyst solution to the crosslinking agent solution is 1:1 to 30.

7. The method for preparing a hydrogel with the animal glue layer removed according to claim 1, characterized in that, In step (2), the polymerization temperature is 50℃ and the time is 5min; the curing temperature is 50℃ and the time is 5~30min.

8. The hydrogel with animal glue layer removed prepared by the method for preparing the hydrogel with animal glue layer removed according to any one of claims 1 to 7.

9. The application of the hydrogel for removing animal glue layers as a cleaning tool in the field of cultural heritage preservation, as described in claim 8, is characterized in that... Applications include the spine adhesive of ancient books, the adhesive layer or backing paper of paintings, and the mortise and tenon joints or surface adhesive residue of wooden furniture.

10. The application according to claim 9, characterized in that, The method of application includes: covering the area to be cleaned with hydrogel, maintaining contact at 45~50°C until the animal glue layer softens, and completely peeling the hydrogel along with the adsorbed softened animal glue layer from the surface of the object to be cleaned.

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