Treatment method and composite treatment agent for enhancing salt weathering resistance of sandstone cultural relics
By combining sandstone surface modifiers and polymer prepolymers in sandstone artifacts, a three-dimensional network structure is formed, which solves the problems of limited penetration depth and surface salt blooming in existing technologies, and achieves stronger resistance to salt weathering and structural enhancement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-22
- Publication Date
- 2026-03-27
AI Technical Summary
Existing technologies, while enhancing the salt weathering resistance of sandstone artifacts, have limited penetration depth, making it difficult to effectively suppress surface salt blooming and potentially leading to decreased air permeability and damage to the internal structure.
By combining the preparation of sandstone surface modifier and polymer prepolymer liquid, LDTS solution is first penetrated into the sandstone surface to react with silanol groups, and then zwitterionic polymer prepolymer liquid is penetrated and polymerized in situ inside the sandstone to form a three-dimensional network structure with enhanced topological entanglement points, thereby enhancing the structural strength of the sandstone and inhibiting salt crystallization.
It significantly improves the resistance of sandstone artifacts to salt weathering, prolongs the time of quality loss caused by salt weathering, reduces the quantity and size of salt crystals, and prevents salt blooming on the sandstone surface.
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Figure CN121735679A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of sandstone cultural relic protection, and particularly relates to a treatment method for enhancing the salt weathering resistance of sandstone cultural relics and a composite treatment agent. BACKGROUND
[0002] Outdoor sandstone cultural relics are introduced with soluble salt due to capillary absorption of underground water, degradation of rock components and rainfall. Under the repeated dissolution-crystallization of salt, the sandstone matrix appears in the form of strength reduction and surface salt, which seriously affects the historical or artistic value of the sandstone cultural relics.
[0003] The scientific method commonly used at present to enhance the salt weathering resistance of sandstone is to use protective materials such as acrylic high polymer and organic hybrid nanoparticles, which is to supplement the lost cementing material of the sandstone cultural relics to enhance the structural strength of the sandstone cultural relics. However, the penetration depth of the pre-formed polymer solution or organic hybrid nanomaterials is limited when they are used for protection, and the functional groups thereon are difficult to interact with inorganic salt to fundamentally inhibit the surface salt phenomenon. In addition, the use of hydrophobic materials will cause a hydrophobic / hydrophilic interface to appear in the interior of the sandstone cultural relics, which seriously affects the air permeability of the sandstone and blocks the water migration channel of the sandstone, and more likely causes the soluble salt to accumulate at the interface through the underground water, resulting in the hidden danger of destructive fracture. SUMMARY
[0004] In view of the problems in the prior art, the application provides a treatment method for enhancing the salt weathering resistance of sandstone cultural relics and a composite treatment agent, which can inhibit the surface salt phenomenon of the sandstone cultural relics while enhancing the structural strength of the sandstone cultural relics, and is beneficial to improving the salt weathering resistance of the sandstone cultural relics.
[0005] In order to solve the above technical problems, the application is implemented by the following technical scheme: According to a first aspect of the application, a treatment method for enhancing the salt weathering resistance of sandstone cultural relics is provided, comprising: Preparation of a sandstone surface modifier: using triethylamine as an acid-binding agent, a nucleophilic substitution reaction of glycerol carbonate and terephthaloyl chloride is carried out in an ice water bath, and a double five-membered ring carbonate is obtained after purification and drying; the double five-membered ring carbonate and 3-aminopropyltriethoxysilane are dissolved in an organic solvent, and heated to react to obtain a sandstone surface modifier LDTS solution; Preparation of a polymer prepolymer solution: in the presence of an initiator system, a free radical copolymerization reaction of methacrylic acid sulfobetaine and 3-methacryloyloxypropyltrimethoxysilane is initiated at low temperature to obtain an amphoteric ion polymer prepolymer solution; Sequential treatment and in-situ enhancement: the LDTS solution is infiltrated into the sandstone matrix to be protected, and the LDTS solution reacts with the silicon hydroxyl groups on the surface of the sandstone; then, the zwitterionic polymer prepolymer solution is infiltrated into the sandstone matrix treated by the LDTS, and the copolymer and monomer in the zwitterionic polymer prepolymer solution are polymerized in-situ in the sandstone, and the siloxane groups in the side chains of the polymer are dehydrated and condensed with the siloxane reaction sites introduced by the LDTS on the surface of the sandstone, thereby forming a three-dimensional network structure reinforced by topological entanglement points in the sandstone.
[0006] In a possible implementation manner of the first aspect, in the step of preparing the sandstone surface modifier, the molar ratio of glycerol carbonate, terephthaloyl dichloride and triethylamine is (2.0-2.4) : 1 : (2.0-2.2), the nucleophilic substitution reaction time is 5-8 hours; the reaction molar ratio of the double five-membered ring carbonate and 3-aminopropyl triethoxysilane is 1 : (2-2.4), the reaction temperature is 50-65 DEG C, and the reaction time is 6-10 hours; and the concentration of the LDTS solution is 1.0 wt%-5.0 wt%.
[0007] In a possible implementation manner of the first aspect, in the step of preparing the polymer prepolymer solution, the initiator system is an oxidation-reduction system of ammonium persulfate and tetramethyl ethylenediamine, wherein the molar ratio of the ammonium persulfate and the tetramethyl ethylenediamine is (1.5-2.5) : 1, and the total amount of the initiator is 3%-5% of the total amount of substance of the methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane.
[0008] In a possible implementation manner of the first aspect, in the step of preparing the polymer prepolymer solution, the reaction molar ratio of the methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane is (2-5) : 1; and in the zwitterionic polymer prepolymer solution, the total mass fraction of the methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane is 3 wt%-7 wt%.
[0009] In a possible implementation manner of the first aspect, in the step of preparing the polymer prepolymer solution, the solvent used is subjected to nitrogen bubbling treatment for more than 10 minutes before the reaction, the reaction temperature is 35-45 DEG C, and the reaction time is 1-3 hours.
[0010] In a possible implementation manner of the first aspect, in the sequential treatment and in-situ enhancement step, a ratio of a mass of the sandstone surface modifier compound contained in the LDTS solution to a total mass of the copolymer and monomer contained in the zwitterionic polymer prepolymer solution is 1:(3-9); and in a mixed solution of the LDTS solution and the zwitterionic polymer prepolymer solution used for the sequential permeation treatment, a sum of the mass of the sandstone surface modifier compound and the total mass of the copolymer and monomer accounts for 2 wt% to 7 wt% of a total mass of the mixed solution.
[0011] In a possible implementation manner of the first aspect, in the sequential treatment and in-situ enhancement step, before the zwitterionic polymer prepolymer solution is permeated into the sandstone, oxalic acid is added in a form of a saturated solution, and an added amount of the oxalic acid is 4 wt% to 10 wt% of the total mass of the copolymer and monomer contained in the zwitterionic polymer prepolymer solution.
[0012] In a possible implementation manner of the first aspect, in the sequential treatment and in-situ enhancement step, after the LDTS solution is permeated into the sandstone, the reaction is performed at room temperature for 6 to 12 hours.
[0013] According to a second aspect of the present application, a composite treatment agent for sandstone cultural relic protection is provided, which is composed of a sandstone surface modifier and a polymer prepolymer solution: The sandstone surface modifier is a solution containing a compound obtained by reacting a bis-pentacyclic carbonate with 3-aminopropyl triethoxysilane, wherein the concentration of the compound is configured to be 1.0 wt% to 5.0 wt%; The polymer prepolymer solution is a prepolymer solution containing a copolymer of methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane, wherein a reaction molar ratio of the methacrylic acid sulfobetaine to the 3-methacryloyloxypropyl trimethoxysilane is (2-5):1, and a total mass fraction of the methacrylic acid sulfobetaine and the 3-methacryloyloxypropyl trimethoxysilane is 3 wt% to 7 wt%; The mass ratio of the sandstone surface modifier to the solute in the polymer prepolymer solution is 1:(3-9).
[0014] According to a third aspect of the present application, a method for enhancing salt weathering resistance of sandstone cultural relics is provided, which applies the composite treatment agent, and includes: The sandstone surface modifier is permeated into the sandstone cultural relics to be protected to perform surface modification; Subsequently, the polymer prepolymer solution is permeated into the modified sandstone to complete an in-situ polymerization reaction in the sandstone pores.
[0015] Compared with the prior art, the present application has at least the following beneficial effects: The two solutions are sequentially infiltrated into the sandstone, and after the LDTS solution is infiltrated into the sandstone, the siloxane at one end is bonded with the silanol on the surface of the sandstone to introduce a large number of siloxane reaction sites to the surface of the sandstone; then the amphoteric ion polymer prepolymer solution is infiltrated into the modified sandstone to realize in-situ polymerization, and at the same time, dehydration condensation occurs between the siloxane reaction sites on the surface of the sandstone during the polymerization process, so as to realize the in-situ construction of the three-dimensional network structure reinforced by topological entanglement points. Specifically, the LDTS of the present application is terephthalate-based hexaethoxysilane double-end sandstone surface modifier, after it is infiltrated into the sandstone, the siloxane at one end is bonded with the silanol on the surface of the sandstone, and the siloxane at the other end of the molecular chain is exposed to introduce a large number of siloxane reaction sites, thereby significantly enhancing the chemical bonding and interfacial synergy between the sandstone matrix and the protective material. The sulfobetaine group in the amphoteric ion prepolymer solution synthesized by the present application can be adsorbed on the free salt ions in the salt solution through strong electrostatic interaction, thereby reducing the ion activity of the salt solution and reducing the total amount of salt crystals in the rock interstice; at the same time, the sulfobetaine can regulate the crystallization orientation of sodium sulfate, and induce it to form a crystal morphology with a smaller size, thereby further weakening the salt crystallization pressure. In addition, the low-viscosity polymer prepolymer solution will polymerize under the continuous initiation of the initiator while infiltrating into the target depth, thereby achieving the enhancement of the structural strength of the protective material in the deep weathering layer. The simultaneously hydrolyzed side chain siloxane and the pre-anchored LDTS siloxane on the surface of the sandstone condense to construct an interpenetrating- interlocking amphoteric ion-based three-dimensional topological network in-situ, thereby significantly improving the mechanical strength of the sandstone matrix and effectively inhibiting the damage of salt crystallization expansion stress to stone cultural relics during the subsequent desalination process. BRIEF DESCRIPTION OF DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application, the drawings needed in the specific embodiment description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.
[0017] Figure 1 The principle of in-situ construction of a topological amphoteric ion polymer network in the sandstone by the treatment method of the present application is illustrated.
[0018] Figure 2 The quality retention rate change of the sandstone protected by the treatment method described in Examples 1-3 in the salt aging cycle experiment is shown.
[0019] Figure 3The optical photos (a) and scanning electron microscope (SEM) images of the surface of the sandstone after two salt aging cycles after the protection by the treatment method described in Example 1 and 3, wherein (b)-(d) in the figure are SEM pictures of the surface of the sandstone without protection, the sandstone after the protection of Example 1 and the sandstone after the protection of Example 3, respectively. DETAILED DESCRIPTION
[0020] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the present application will be described clearly and completely below with reference to the drawings, obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.
[0021] Example 1 A treatment method for enhancing the salt weathering resistance of sandstone cultural relics, specifically as follows: Step one, preparation of sandstone surface modifier: take triethylamine as acid-binding agent, make nucleophilic substitution reaction of glycerol carbonate and terephthaloyl chloride in ice water bath, purify and dry the reaction product to obtain double five-membered ring carbonate; dissolve the double five-membered ring carbonate and 3-aminopropyl triethoxysilane in organic solvent, heat to react to obtain sandstone surface modifier LDTS solution, LDTS is linear silane coupling agent terephthalate hexaethoxysilane.
[0022] Specifically, the molar ratio of the glycerol carbonate, terephthaloyl chloride and triethylamine is 2.3:1:2.0, the reaction time is 6 hours, and the reaction solvent is dichloromethane; the reaction molar ratio of the double five-membered ring carbonate and 3-aminopropyl triethoxysilane is 1:2.0, the reaction temperature is 60°C, the reaction time is 8 hours, and the reaction solvent is a mixed solvent of acetonitrile and ethanol, and the volume ratio of acetonitrile to ethanol is 2:1; the concentration of the LDTS solution is 1.0 wt%.
[0023] Step two, preparation of polymer prepolymer solution: in the presence of initiator system, initiate free radical copolymerization of methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane at low temperature to obtain amphoteric ion polymer prepolymer solution.
[0024] Specifically, the initiator system is an oxidation-reduction system of ammonium persulfate and tetramethyl ethylenediamine, wherein the molar ratio of the ammonium persulfate to tetramethyl ethylenediamine is 2.0:1, and the total amount of the initiator is 5% of the total amount of substances of the methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane.
[0025] Specifically, the reaction molar ratio of the methacryl sulfobetaine and 3-methacryloxypropyl trimethoxysilane is 3:1, the prepolymer solution is prepared by using a mixed solvent of ethanol and water, and the volume ratio of ethanol to water is 2.5:1; the total mass fraction of the methacryl sulfobetaine and 3-methacryloxypropyl trimethoxysilane in the zwitterionic polymer prepolymer solution is 4 wt%.
[0026] Specifically, the used solvent is subjected to nitrogen bubbling treatment for 10 minutes before the reaction, the reaction temperature is 40°C, and the reaction time is 3 hours.
[0027] Specifically, the total mass ratio of the sandstone surface modifier compound to the copolymer and monomer in the LDTS solution and the zwitterionic polymer prepolymer solution for sequential treatment is 1:6; and the total mass of the sandstone surface modifier compound and the copolymer and monomer in the mixed solution accounts for 4 wt% of the total mass of the mixed solution.
[0028] Specifically, before the zwitterionic polymer prepolymer solution is penetrated into the sandstone, oxalic acid is added in the form of a saturated solution, and the added amount of the oxalic acid is 7 wt% of the total mass of the copolymer and monomer contained in the zwitterionic polymer prepolymer solution.
[0029] The treatment method of this embodiment is used to protect the sandstone, which is divided into two stages: first, the LDTS solution is penetrated into the sandstone, and a large number of siloxane reaction sites are introduced on the surface of the sandstone at room temperature; second, the zwitterionic polymer prepolymer solution is penetrated into the modified sandstone to realize in-situ polymerization (if the on-site temperature is low, infrared light can be used to speed up the reaction rate), and at the same time, the siloxane groups of the polymer side chains and the siloxane reaction sites introduced on the surface of the sandstone via the LDTS undergo dehydration condensation, thereby forming a three-dimensional network structure reinforced by topological entanglement points inside the sandstone.
[0030] Specifically, the LDTS solution is suspended and dripped to penetrate into the sandstone cultural relics to be protected, and the sandstone surface modification is carried out at room temperature for 12 hours. After the sandstone surface modification is completed, the zwitterionic polymer prepolymer solution is suspended and dripped to penetrate into the sandstone, thereby completing the protection of the sandstone cultural relics.
[0031] After the protection is completed, the protection effect of this embodiment is tested by a salt aging program and the morphology of the sandstone surface during the aging process. The protected sandstone is placed in 0.5 mol L -¹ Immersed in Na2SO4 solution for 2 h, wiped off the surface liquid drops with a wet towel after taking out, then put into the temperature and humidity alternating box, run according to the procedure of 25 °C / 50 %RH-2 h, increased to 95 °C / 90 %RH within 2 h, 95 °C / 90 %RH-8 h, decreased back to 25 °C / 50 %RH within 2 h, 25 °C / 50 %RH-8 h, then immersed in a new 0.5 mol / L Na2SO4 solution again - ¹ One salt weathering cycle can be completed after 2 h of Na2SO4 solution; after each cycle, the mass retention rate is calculated to evaluate the enhancement effect of the protective material on the salt weathering resistance of sandstone.
[0032] After the end of the second cycle, the surface slice was cut, gold spraying treatment was performed, and the morphology and element distribution were observed and collected by SEM-EDX (Gemini 500) to evaluate the ability of the protective material to inhibit salt from spreading on the surface of the sandstone.
[0033] Figure 1 The left figure shows the process of zwitterionic polymer prepolymer penetrating into the LDTS modified sandstone, and the right figure shows the mode of action of the protective sandstone after the zwitterionic polymerization is completed. With the occurrence of polymerization in the sandstone, zwitterionic polymers are gradually generated in the sandstone pores, and the polymer chains grow randomly in the random initiation process, forming a topological entanglement; the methoxysilane side chain of the polymer hydrolyzes and condenses with the ethoxysilane modified on the surface of the sandstone, further enhancing the reinforcement effect of the protective material on the sandstone. In addition, the sulfobetaine group on the side chain combines with salt ions due to ionic interaction, which reduces the ionic activity of soluble salt in the sandstone, weakens the salt crystallization pressure and total amount of salt crystallization in the pores, and further enhances the salt weathering resistance of the sandstone cultural relics.
[0034] Figure 2 The mass retention of the sandstone protected by the method of the present embodiment in the salt weathering cycle is shown in the light gray. The salt weathering resistance of the sandstone protected by the method of the present embodiment is greatly improved, and the mass loss starts at the 9th cycle, which is 1.25 times higher than that of the unprotected sandstone at the 4th cycle. Based on the criterion that the mass loss of sandstone exceeds 60%, the cycle number of the sandstone protected by the method of the present embodiment is 17, which is 1.8 times higher than that of the unprotected sandstone at the 6th cycle.
[0035] Figure 3 The optical photo and SEM image of the surface of the sandstone protected by the method of the present embodiment after two salt cycles. Figure 3(a) in FIG. 1 shows the optical photos of salt crystallization on the sandstone surface after two aging cycles. A large number of white Na2SO4crystals can be observed on the sandstone surface without the protection of the embodiment, while the white Na2SO4crystals on the sandstone surface after the protection of the embodiment are significantly reduced, directly showing the effect of the embodiment on inhibiting the salt on the sandstone surface. Figure 3 (b) in FIG. 1 is the SEM picture of the sandstone without protection after two aging cycles, Figure 3 (c) in FIG. 1 shows the SEM picture of the sandstone surface after the protection of the embodiment. Through EDS energy spectrum scanning, it is found that the atomic percentage of Na element on the sandstone surface after the protection is 4.52%, which is decreased by 75.26% compared with the atomic percentage of Na element on the sandstone surface without protection, which is 18.27%. The above data shows that the method has the effect of enhancing the salt weathering resistance of sandstone cultural relics and inhibiting the salt on the sandstone surface.
[0036] Embodiment 2 A treatment method for enhancing the salt weathering resistance of sandstone cultural relics, characterized in that the method comprises the following steps: Step 1: preparing a sandstone surface modifier. Glyceryl carbonate is subjected to a nucleophilic substitution reaction with terephthaloyl chloride in an ice water bath with triethylamine as an acid-binding agent to obtain a double five-membered ring carbonate after purification and drying. The double five-membered ring carbonate and 3-aminopropyl triethoxysilane are dissolved in an organic solvent and heated to react to obtain a sandstone surface modifier LDTS solution.
[0037] Specifically, the molar ratio of the glyceryl carbonate, terephthaloyl chloride and triethylamine is 2.3:1:2.0, the reaction time is 7 hours, and the reaction solvent is dichloromethane. The reaction molar ratio of the double five-membered ring carbonate and 3-aminopropyl triethoxysilane is 1:2.1, the reaction temperature is 55°C, the reaction time is 8 hours, the reaction solvent is a mixed solvent of acetonitrile and ethanol, and the volume ratio of acetonitrile to ethanol is 2:1. The concentration of the LDTS solution is 2.0 wt%.
[0038] Step 2: preparing a polymer prepolymer solution. In the presence of an initiator system, a free radical copolymerization reaction of methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane is initiated at low temperature to obtain an amphoteric ion polymer prepolymer solution.
[0039] Specifically, the initiator system is an oxidation-reduction system of ammonium persulfate and tetramethyl ethylenediamine, wherein the molar ratio of the ammonium persulfate to the tetramethyl ethylenediamine is 2.0:1, and the total amount of the initiator is 5% of the total amount of substances of the methacrylic acid sulfobetaine and the 3-methacryloyloxypropyl trimethoxysilane.
[0040] Specifically, the reaction molar ratio of the methacrylic sulfobetaine and 3-methacryloxypropyl trimethoxysilane is 4:1, the pre-polymer solution is prepared by using a mixed solvent of ethanol and water, and the volume ratio of ethanol to water is 2:1; the total mass fraction of the methacrylic sulfobetaine and 3-methacryloxypropyl trimethoxysilane in the zwitterionic polymer pre-polymer solution is 5 wt%.
[0041] Specifically, the used solvent is subjected to nitrogen bubbling treatment for 10 minutes before the reaction, the reaction temperature is 40°C, and the reaction time is 2 hours.
[0042] Specifically, the total mass ratio of the sandstone surface modifier compound to the copolymer and monomer in the LDTS solution and the zwitterionic polymer pre-polymer solution for sequential treatment is 1:9; and the total mass of the sandstone surface modifier compound and the copolymer and monomer in the mixed solution accounts for 6 wt% of the total mass of the mixed solution.
[0043] Specifically, before the zwitterionic polymer pre-polymer solution is penetrated into the sandstone, oxalic acid is added in the form of a saturated solution, and the added amount of the oxalic acid is 10 wt% of the total mass of the copolymer and monomer contained in the zwitterionic polymer pre-polymer solution.
[0044] The treatment method of this embodiment is used to protect the sandstone, which is divided into two stages: first, the LDTS solution is penetrated into the sandstone, and the reaction is carried out at room temperature to introduce siloxane reaction sites on the surface of the sandstone; second, the zwitterionic polymer pre-polymer solution is penetrated into the modified sandstone to realize in-situ polymerization, and at the same time, the siloxane groups of the polymer side chains and the siloxane reaction sites introduced on the surface of the sandstone via the LDTS undergo dehydration condensation, thereby forming a three-dimensional network structure reinforced by topological entanglement points inside the sandstone.
[0045] Specifically, the LDTS solution is suspended and dripped to penetrate into the sandstone cultural relics to be protected, and the reaction is carried out at room temperature for 10 hours to modify the surface of the sandstone. After the surface modification of the sandstone is completed, the zwitterionic polymer pre-polymer solution is suspended and dripped to penetrate into the sandstone, thereby completing the protection of the sandstone cultural relics.
[0046] After the protection is completed, the salt aging procedure is used for testing, and the method is the same as that of Example 1.
[0047] Figure 2The quality retention of sandstone protected by the method of the embodiment in salt weathering cycles. The salt weathering resistance of the sandstone protected by the embodiment is greatly improved, and the time when the quality starts to be lost is the 13th cycle, which is 2.25 times higher than the 4th cycle of the unprotected sandstone. Based on the criterion that the mass loss of sandstone is more than 60%, the cycle number of the sandstone protected by the embodiment is the 20th, which is 2.3 times higher than the 6th cycle of the unprotected sandstone.
[0048] Figure 3 (a) in the above figure indicates the optical photograph of salt crystallization on the surface of sandstone after two aging cycles. A large number of white Na2SO4 crystals can be observed on the surface of the sandstone without protection by the embodiment, while the white Na2SO4 crystals on the surface of the sandstone protected by the embodiment are significantly reduced, directly showing the effect of the embodiment in inhibiting salt on the surface of sandstone.
[0049] Embodiment 3 A treatment method for enhancing the salt weathering resistance of sandstone cultural relics, specifically as follows: Step one, preparation of sandstone surface modifier: using triethylamine as an acid-binding agent, nucleophilic substitution reaction of glycerol carbonate and terephthaloyl chloride is carried out in an ice water bath, and after purification and drying, a double five-membered ring carbonate is obtained; the double five-membered ring carbonate and 3-aminopropyl triethoxysilane are dissolved in an organic solvent and heated to react to obtain a sandstone surface modifier LDTS solution.
[0050] Specifically, the molar ratio of glycerol carbonate, terephthaloyl chloride and triethylamine is 2.2:1:2.0, the reaction time is 6 hours, and the reaction solvent is dichloromethane; the reaction molar ratio of the double five-membered ring carbonate and 3-aminopropyl triethoxysilane is 1:2.2, the reaction temperature is 60°C, the reaction time is 8 hours, and the reaction solvent is a mixed solvent of acetonitrile and ethanol, and the volume ratio of acetonitrile to ethanol is 2:1; the concentration of the LDTS solution is 1.0 wt%.
[0051] Step two, preparation of polymer prepolymer solution: in the presence of an initiator system, free radical copolymerization of methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane is initiated at low temperature to obtain an amphoteric polymer prepolymer solution.
[0052] Specifically, the initiator system is an oxidation-reduction system of ammonium persulfate and tetramethyl ethylenediamine, wherein the molar ratio of ammonium persulfate to tetramethyl ethylenediamine is 2.0:1, and the total amount of the initiator is 5% of the total amount of the methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane.
[0053] Specifically, the reaction molar ratio of the methacrylic sulfobetaine and 3-methacryloxypropyl trimethoxysilane is 3:1, the pre-polymer solution is prepared by using a mixed solvent of ethanol and water, and the volume ratio of ethanol to water is 2:1; the total mass fraction of the methacrylic sulfobetaine and 3-methacryloxypropyl trimethoxysilane in the zwitterionic polymer pre-polymer solution is 6 wt%.
[0054] Specifically, the used solvent is subjected to nitrogen bubbling treatment for 10 minutes before the reaction, the reaction temperature is 40°C, and the reaction time is 2 hours.
[0055] Specifically, the total mass ratio of the sandstone surface modifier compound to the copolymer and monomer in the LDTS solution and the zwitterionic polymer pre-polymer solution for sequential treatment is 1:7; and the total mass of the sandstone surface modifier compound and the copolymer and monomer in the mixed solution accounts for 5 wt% of the total mass of the mixed solution.
[0056] Specifically, before the zwitterionic polymer pre-polymer solution is penetrated into the sandstone, oxalic acid is added in the form of a saturated solution, and the added amount of the oxalic acid is 8 wt% of the total mass of the copolymer and monomer contained in the zwitterionic polymer pre-polymer solution.
[0057] The treatment method of this embodiment is used to protect the sandstone, which is divided into two stages: first, the LDTS solution is penetrated into the sandstone, and the reaction is carried out at room temperature to introduce siloxane reaction sites on the surface of the sandstone; second, the zwitterionic polymer pre-polymer solution is penetrated into the modified sandstone to realize in-situ polymerization, and at the same time, the siloxane groups of the copolymer side chains and the siloxane reaction sites introduced on the surface of the sandstone via the LDTS undergo dehydration condensation, thereby forming a three-dimensional network structure reinforced by topological entanglement points inside the sandstone.
[0058] Specifically, the LDTS solution is suspended and dripped to penetrate into the sandstone cultural relics to be protected, and the reaction is carried out at room temperature for 6 hours to modify the surface of the sandstone. After the modification of the surface of the sandstone is completed, the zwitterionic polymer pre-polymer solution is suspended and dripped to penetrate into the sandstone, thereby completing the protection of the sandstone cultural relics.
[0059] After the protection is completed, the salt aging procedure is used for testing, and the method is the same as that of Example 1.
[0060] Figure 2The quality retention of sandstone protected by the method of the embodiment in salt weathering cycles. The salt weathering resistance of the sandstone protected by the embodiment is greatly improved, and the time when the quality starts to be lost is the 15th cycle, which is 2.75 times higher than the 4th cycle of the unprotected sandstone. Based on the criterion that the mass loss of sandstone is more than 60%, the cycle number of the sandstone protected by the embodiment is the 25th, which is 3.2 times higher than the 6th cycle of the unprotected sandstone.
[0061] Figure 3 (a) in FIG. 6 shows the optical photos of the salt crystals on the surface of the sandstone after two aging cycles. A large number of white Na2SO4 crystals can be observed on the surface of the unprotected sandstone, while the white Na2SO4 crystals on the surface of the sandstone protected by the embodiment are significantly reduced, directly showing the effect of the embodiment in inhibiting salt on the surface of the sandstone. Figure 3 (d) in FIG. 6 is the optical photo and SEM image of the surface of the sandstone protected by the method of the embodiment after two salt cycles. Through EDS energy spectrum scanning, it is found that the atomic percentage of Na element on the surface of the protected sandstone is 3.27%, which is 82.10% lower than the atomic percentage of Na element on the surface of the unprotected sandstone, which is 18.27%. The above data shows that the method has the effect of enhancing the salt weathering resistance of sandstone cultural relics and inhibiting salt on the surface of sandstone.
[0062] Embodiment 4 A treatment method for enhancing the salt weathering resistance of sandstone cultural relics, specifically as follows: Step one, preparation of sandstone surface modifier: using triethylamine as an acid-binding agent, nucleophilic substitution reaction of glycerol carbonate and terephthaloyl chloride is carried out in an ice water bath, and after purification and drying, a double five-membered ring carbonate is obtained; the double five-membered ring carbonate and 3-aminopropyl triethoxysilane are dissolved in an organic solvent and heated to react to obtain a sandstone surface modifier LDTS solution.
[0063] Specifically, the molar ratio of glycerol carbonate, terephthaloyl chloride and triethylamine is 2.4:1:2.1, the reaction time is 8 hours, and the reaction solvent is dichloromethane; the reaction molar ratio of the double five-membered ring carbonate and 3-aminopropyl triethoxysilane is 1:2.2, the reaction temperature is 50°C, the reaction time is 6 hours, and the reaction solvent is a mixed solvent of acetonitrile and ethanol, and the volume ratio of acetonitrile to ethanol is 4:1; the concentration of the LDTS solution is 5.0 wt%.
[0064] Step two, preparation of polymer prepolymer solution: in the presence of an initiator system, free radical copolymerization of methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane is initiated at low temperature to obtain an amphoteric polymer prepolymer solution.
[0065] Specifically, the initiator system is a redox system of ammonium persulfate and tetramethyl ethylenediamine, wherein the molar ratio of ammonium persulfate to tetramethyl ethylenediamine is 1.5:1, and the total amount of the initiator is 3% of the total mass of the methacrylic sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane.
[0066] Specifically, the reaction molar ratio of the methacrylic sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane is 5:1, the prepolymer solution is prepared by using a mixed solvent of ethanol and water, and the volume ratio of ethanol to water is 2:1; the total mass fraction of the methacrylic sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane in the zwitterionic polymer prepolymer solution is 3 wt%.
[0067] Specifically, the solvent used is subjected to nitrogen bubbling treatment for 10 minutes before the reaction, the reaction temperature is 35°C, and the reaction time is 1 hour.
[0068] Specifically, in the LDTS solution and the zwitterionic polymer prepolymer solution used for sequential treatment, the mass ratio of the sandstone surface modifier compound to the total mass of the copolymer and monomer is 1:3; and the sum of the mass of the sandstone surface modifier compound and the total mass of the copolymer and monomer in the mixed solution accounts for 2 wt% of the total mass of the mixed solution.
[0069] Specifically, before the zwitterionic polymer prepolymer solution is penetrated into the sandstone, oxalic acid is added in the form of a saturated solution, and the amount of the oxalic acid added is 4 wt% of the total mass of the copolymer and monomer contained in the zwitterionic polymer prepolymer solution.
[0070] The treatment method of this embodiment is used to protect the sandstone, which is divided into two stages: first, the LDTS solution is penetrated into the sandstone, and the reaction is carried out at room temperature to introduce siloxane reaction sites on the surface of the sandstone; second, the zwitterionic polymer prepolymer solution is penetrated into the modified sandstone to realize in-situ polymerization, and at the same time, the siloxane groups of the polymer side chains and the siloxane reaction sites introduced on the surface of the sandstone via the LDTS undergo dehydration condensation, thereby forming a three-dimensional network structure reinforced by topological entanglement points inside the sandstone.
[0071] Specifically, the LDTS solution is suspended and dripped to penetrate into the sandstone cultural relics to be protected, and the reaction is carried out at room temperature for 8 hours to modify the surface of the sandstone. After the surface modification of the sandstone is completed, the zwitterionic polymer prepolymer solution is suspended and dripped to penetrate into the sandstone, thereby completing the protection of the sandstone cultural relics.
[0072] In the present embodiment, the sandstone sample protected by the method and parameters described is subjected to the same salt weathering test as in Example 1, and the salt weathering resistance is also significantly enhanced, and the surface salt phenomenon is effectively inhibited, and the effect is equivalent to that of Examples 1-3.
[0073] Example 5 A treatment method for enhancing the salt weathering resistance of sandstone cultural relics, specifically as follows: Step 1, preparation of sandstone surface modifier: nucleophilic substitution reaction of glycerol carbonate and terephthaloyl chloride in an ice water bath with triethylamine as an acid-binding agent, and after purification and drying, a double five-membered ring carbonate is obtained; the double five-membered ring carbonate and 3-aminopropyl triethoxysilane are dissolved in an organic solvent and heated to react to obtain a sandstone surface modifier sandstone LDTS solution.
[0074] Specifically, the molar ratio of glycerol carbonate, terephthaloyl chloride and triethylamine is 2.0:1:2.2, the reaction time is 5 hours, and the reaction solvent is dichloromethane; the reaction molar ratio of the double five-membered ring carbonate and 3-aminopropyl triethoxysilane is 1:2.4, the reaction temperature is 65°C, the reaction time is 10 hours, and the reaction solvent is a mixed solvent of acetonitrile and ethanol, and the volume ratio of acetonitrile to ethanol is 3:1; the concentration of the LDTS solution is 3.0 wt%.
[0075] Step 2, preparation of polymer prepolymer solution: free radical copolymerization of methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane at low temperature in the presence of an initiator system to obtain an amphoteric ion polymer prepolymer solution.
[0076] Specifically, the initiator system is an oxidation-reduction system of ammonium persulfate and tetramethyl ethylenediamine, wherein the molar ratio of ammonium persulfate to tetramethyl ethylenediamine is 2.5:1, and the total amount of the initiator is 4% of the total mass of the methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane.
[0077] Specifically, the reaction molar ratio of the methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane is 2:1, the prepolymer solution is prepared by a mixed solvent of ethanol and water, and the volume ratio of ethanol to water is 3:1; the total mass fraction of the methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane in the amphoteric ion polymer prepolymer solution is 7 wt%.
[0078] Specifically, the solvents used are subjected to nitrogen bubbling treatment for 10 minutes before the reaction, the reaction temperature is 45°C, and the reaction time is 2 hours.
[0079] Specifically, the ratio of the sandstone surface modifier compound to the total mass of the copolymer and monomer in the LDTS solution for sequential treatment and the zwitterionic polymer prepolymer solution is 1:4; and the sum of the mass of the sandstone surface modifier compound and the total mass of the copolymer and monomer in the mixed solution accounts for 7 wt% of the total mass of the mixed solution.
[0080] Specifically, before the zwitterionic polymer prepolymer solution is penetrated into the sandstone, oxalic acid is added in the form of a saturated solution, and the amount of the oxalic acid added is 5 wt% of the total mass of the copolymer and monomer contained in the zwitterionic polymer prepolymer solution.
[0081] The treatment method of this embodiment is used to protect the sandstone, which is divided into two stages: first, the LDTS solution is penetrated into the sandstone, and the reaction is carried out at room temperature to introduce siloxane reaction sites on the surface of the sandstone; second, the zwitterionic polymer prepolymer solution is penetrated into the modified sandstone to realize in-situ polymerization, and at the same time, the siloxane groups of the polymer side chains and the siloxane reaction sites introduced on the surface of the sandstone via the LDTS undergo dehydration condensation, thereby forming a three-dimensional network structure reinforced by topological entanglement points inside the sandstone.
[0082] Specifically, the LDTS solution is suspended and dripped to penetrate into the sandstone cultural relics to be protected, and the reaction is carried out at room temperature for 12 hours to modify the surface of the sandstone. After the surface modification of the sandstone is completed, the zwitterionic polymer prepolymer solution is suspended and dripped to penetrate into the sandstone, thereby completing the protection of the sandstone cultural relics.
[0083] In this embodiment, the sandstone sample protected by the method and parameters described therein is tested by the same salt aging program as in Example 1, and its salt weathering resistance is also significantly enhanced, and the surface salt phenomenon is effectively inhibited, with an effect comparable to that of Example 1-3.
[0084] The LDTS acts as a sandstone surface modifier to increase the active sites on the surface of the sandstone. The zwitterionic polymer prepolymer solution is injected in the form of a low-viscosity solution, and the methacrylic acid sulfobetaine and 3-methacryloyloxypropyl trimethoxysilane further polymerize under the action of continuously initiated free radicals during penetration. The simultaneously hydrolyzed siloxane condenses with the pre-anchored LDTS siloxane on the surface of the sandstone, in-situ constructing an interpenetrating-interlocking zwitterionic-based three-dimensional topological network, significantly improving the overall mechanical strength of the matrix, and effectively inhibiting the damage of salt crystallization pressure to stone cultural relics during the subsequent desalination process. In addition, the sulfobetaine functional groups on the side chains can adsorb free salt ions in the salt solution through strong electrostatic attraction, reducing the concentration of ions with crystallization activity in the solution, thereby reducing the total amount of salt crystallization in the rock gap and inhibiting the surface salt phenomenon. The dual mechanism of this method can effectively enhance the salt weathering resistance of sandstone cultural relics and inhibit the surface salt phenomenon.
[0085] Finally, it should be noted that the above-described embodiments are merely specific embodiments of the present application, which are used to illustrate the technical solutions of the present application, but not to limit the present application, the protection scope of the present application is not limited to this, although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art within the technical range disclosed by the present application, the technical solutions recorded in the foregoing embodiments can still be modified or easily thought of changes, or equivalent replacement of part of the technical features, and these modifications, changes or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered in the protection scope of the present application.
Claims
1. A method for enhancing the resistance of sandstone cultural relics to salt weathering, characterized in that, include: Preparation of sandstone surface modifier: Triethylamine is used as an acid-binding agent to carry out a nucleophilic substitution reaction between glycerol carbonate and terephthaloyl chloride in an ice-water bath. After purification and drying, a bis-pentane carbonate is obtained. The bis-pentane carbonate is dissolved in an organic solvent with 3-aminopropyltriethoxysilane and heated to react, thus obtaining a sandstone surface modifier LDTS solution. Preparation of polymer prepolymer solution: In the presence of an initiator system, methacrylic acid sulfobetaine and 3-methacryloyloxypropyltrimethoxysilane were initiated at low temperature to undergo a free radical copolymerization reaction to obtain a zwitterionic polymer prepolymer solution; Sequential processing and in-situ reinforcement: The LDTS solution is infiltrated into the sandstone matrix to be protected, allowing the LDTS solution to react with the silanol groups on the sandstone surface; subsequently, the zwitterionic polymer prepolymer solution is infiltrated into the LDTS-treated sandstone matrix, causing the copolymers and monomers in the zwitterionic polymer prepolymer solution to undergo in-situ polymerization inside the sandstone. At the same time, the siloxane groups of the polymer side chains undergo dehydration condensation with the siloxane reaction sites introduced by LDTS on the sandstone surface, thereby forming a three-dimensional network structure reinforced by topological entanglements inside the sandstone.
2. The method for enhancing the resistance of sandstone cultural relics to salt weathering according to claim 1, characterized in that, In the step of preparing the sandstone surface modifier, the molar ratio of glyceryl carbonate, terephthaloyl chloride, and triethylamine is (2.0~2.4):1:(2.0~2.2), and the nucleophilic substitution reaction time is 5~8 hours; the molar ratio of the bispentanone carbonate to 3-aminopropyltriethoxysilane is 1:(2~2.4), the reaction temperature is 50~65℃, and the reaction time is 6~10 hours; the concentration of the LDTS solution is 1.0 wt%~5.0 wt%.
3. The method for enhancing the resistance of sandstone cultural relics to salt weathering according to claim 1, characterized in that, In the step of preparing the polymer prepolymer solution, the initiator system is a redox system of ammonium persulfate and tetramethylethylenediamine, wherein the molar ratio of ammonium persulfate to tetramethylethylenediamine is (1.5~2.5):1, and the total amount of the initiator is 3%~5% of the total molar amount of methacrylic acid sulfobetaine and 3-methacryloyloxypropyltrimethoxysilane.
4. A method for enhancing the resistance of sandstone cultural relics to salt weathering according to claim 1, characterized in that, In the step of preparing the polymer prepolymer solution, the reaction molar ratio of methacrylic acid sulfobetaine to 3-methacryloyloxypropyltrimethoxysilane is (2~5):1; in the zwitterionic polymer prepolymer solution, the total mass fraction of methacrylic acid sulfobetaine and 3-methacryloyloxypropyltrimethoxysilane is 3 wt%~7 wt%.
5. The method for enhancing the resistance of sandstone cultural relics to salt weathering according to claim 1, characterized in that, In the step of preparing the polymer prepolymer liquid, the solvent is subjected to nitrogen bubbling treatment for more than 10 minutes before the reaction, the reaction temperature is 35~45℃, and the reaction time is 1~3 hours.
6. A method for enhancing the resistance of sandstone cultural relics to salt weathering according to claim 1, characterized in that, In the sequential processing and in-situ reinforcement steps, the ratio of the sandstone surface modifier compound contained in the LDTS solution to the total mass of the copolymer and monomer contained in the zwitterionic polymer prepolymer solution is 1:(3~9); and in the mixed solution of the LDTS solution and the zwitterionic polymer prepolymer solution used for sequential infiltration processing, the sum of the total mass of the sandstone surface modifier compound and the copolymer and monomer accounts for 2 wt%~7 wt% of the total mass of the mixed solution.
7. A method for enhancing the resistance of sandstone cultural relics to salt weathering according to claim 6, characterized in that, In the sequential processing and in-situ reinforcement steps, before the zwitterionic polymer prepolymer solution is infiltrated into the sandstone, oxalic acid is added to it in the form of a saturated solution. The amount of oxalic acid added is 4 wt% to 10 wt% of the total mass of the copolymer and monomer contained in the zwitterionic polymer prepolymer solution.
8. The method for enhancing the resistance of sandstone cultural relics to salt weathering according to claim 7, characterized in that, In the sequential processing and in-situ enhancement steps, after the LDTS solution permeates into the sandstone, it reacts at room temperature for 6-12 hours.
9. A composite treatment agent for the preservation of sandstone cultural relics, characterized in that, Composed of sandstone surface modifier and polymer prepolymer liquid: The sandstone surface modifier is a solution containing a compound obtained by reacting a bis-pentanone carbonate with 3-aminopropyltriethoxysilane, wherein the concentration of the compound is configured to be 1.0 wt%~5.0 wt%. The polymer prepolymer solution is a prepolymer solution containing a copolymer of methacrylic acid sulfobetaine and 3-methacryloyloxypropyltrimethoxysilane, wherein the molar ratio of methacrylic acid sulfobetaine to 3-methacryloyloxypropyltrimethoxysilane is (2~5):1, and the total mass fraction of methacrylic acid sulfobetaine and 3-methacryloyloxypropyltrimethoxysilane is 3 wt%~7 wt%. The mass ratio of the sandstone surface modifier to the solute in the polymer prepolymer solution is 1:(3~9).
10. A method for enhancing the resistance of sandstone cultural relics to salt weathering, characterized in that, The composite treatment agent according to claim 9 is used in the following manner: The sandstone surface modifier is penetrated into the interior of the sandstone artifact to be protected to modify its surface. Subsequently, the polymer prepolymer solution is infiltrated into the modified sandstone, allowing it to complete the in-situ polymerization reaction within the sandstone pores.