Nanometer calcium phosphate oligomer for reinforcing cultural relics and preparation method and application thereof

Abstract

The present application relates to a kind of nanometer calcium phosphate oligomer for cultural relics reinforcement and its preparation method and application, will be configured calcium chloride ethanol solution, then add arginine, finally add triethylamine to the mixture described above phosphoric acid is added and stirred 12-24h just can draw nanometer calcium phosphate oligomer, synthesis method is simple, easy to operate.More importantly, the nanometer calcium phosphate oligomer synthesized by the method is applied to cultural relics reinforcement without providing additional calcium source, and there is no requirement for whether the reinforced object contains calcium source.After being applied to ancient murals and stone cultural relics, it is found that the nanometer calcium phosphate oligomer prepared by the present application has good permeability in both and is converted into interlinked crystalline hydroxyapatite with poor crystallinity within 48-60h.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of cultural relic protection materials, and relates to a nano calcium phosphate oligomer for cultural relic reinforcement, and a preparation method and application thereof. BACKGROUND

[0002] Cultural relic reinforcement materials mainly include organic materials and inorganic materials. Organic materials, such as polyacrylic resin, have strong adhesion and little influence on the color of cultural relics, and are the most widely used cultural relic reinforcement materials at present. However, with the wide application of such materials, problems gradually appear: yellowing, brittleness and even failure after a long time. These problems are inherent shortcomings of organic materials. In contrast, inorganic materials exhibit better aging resistance and excellent compatibility with murals, and are the research direction and hotspot of current cultural heritage reinforcement and protection materials. (J. Colloid Interface Sci. 2013, 392, 42-49.) Currently reported inorganic cultural relic reinforcement materials include alkaline earth metal nanohydroxides (such as nano calcium hydroxide, nano barium hydroxide, etc.), calcium phosphate, etc. (Const. Build. Mater., 2024, 431, 136551.) Among them, alkaline earth metal nanohydroxides are the most studied inorganic nanometer cultural relic reinforcement materials, and some have been commercialized. However, such materials mainly achieve reinforcement of cultural relics through carbonation (J. Cult. Herit. 2021, 50, 25-42.), which is a slow process (usually 1 to 2 weeks). In addition, there is an inherent disadvantage of insufficient reinforcement strength. In contrast, calcium phosphate has better effect because it is finally converted into hydroxyapatite with higher strength in cultural relics, which can achieve high-strength reinforcement of cultural relics. However, current calcium phosphate reinforcement of cultural relics requires calcium source in the reinforcement object (such as marble), or directly introduces harmful calcium source (such as calcium chloride) in the cultural relics. In summary, current calcium phosphate reinforcement of cultural relics must provide calcium source. SUMMARY

[0003] Technical problems to be solved

[0004] In order to avoid the shortcomings of the prior art, the present application proposes a nano calcium phosphate oligomer for cultural relic reinforcement, and a preparation method and application thereof.

[0005] Technical scheme

[0006] A preparation method of a nano calcium phosphate oligomer for cultural relic reinforcement, characterized in that the steps are as follows:

[0007] Step 1, prepare a calcium chloride ethanol solution, an arginine aqueous solution and a phosphoric acid ethanol solution:

[0008] Obtain calcium chloride ethanol solution A from calcium chloride dihydrate in ethanol;

[0009] The arginine is added into pure water to prepare arginine aqueous solution B;

[0010] The phosphoric acid solution is added into ethanol to prepare phosphoric acid ethanol solution C;

[0011] Step 2, preparation of nano calcium phosphate oligomer:

[0012] Step 2.1: arginine aqueous solution B is added dropwise into calcium chloride ethanol solution A to obtain calcium chloride solution D containing arginine;

[0013] Step 2.2: triethylamine is added into calcium chloride solution D containing arginine to obtain solution E containing triethylamine;

[0014] Step 2.3: phosphoric acid ethanol solution C is added dropwise into solution E containing triethylamine and stirred; after stirring, nano calcium phosphate oligomer is obtained by centrifugation and washing with ethanol solution.

[0015] The preparation ratio of the calcium chloride ethanol solution A is 2.2-4.4 grams of calcium chloride dihydrate to 50-100 mL of ethanol.

[0016] The preparation ratio of the arginine aqueous solution B is 0.3-0.8 grams of arginine to 10 mL of pure water.

[0017] The preparation ratio of the phosphoric acid ethanol solution C is 0.7 mL-2.8 mL of phosphoric acid solution to 10 mL-40 mL of ethanol.

[0018] In step 2.1, the mixing ratio of each portion of arginine aqueous solution B and calcium chloride ethanol solution A is the amount of claim 2 and claim 3.

[0019] In step 2.2, the amount of triethylamine added is 50 mL-100 mL.

[0020] In step 2.3, the stirring time of adding phosphoric acid ethanol solution C is 12-24 h.

[0021] In step 2.3, the amount of phosphoric acid ethanol solution C added in each portion is the amount of claim 4.

[0022] The application of nano calcium phosphate oligomer prepared by the preparation method of any one of claims 1-8, characterized by: used for reinforcing ancient murals and stone cultural relics.

[0023] The nano calcium phosphate oligomer is ultrasonically dispersed in ethanol to obtain an ethanol solution of the nano calcium phosphate oligomer with a concentration of 10-20 mg / mL; the solution is sprayed on the surface of the ancient mural and stone cultural relics until no absorption occurs, and then the surface excess solution is wiped off with absorbent cotton; then the ancient mural and stone cultural relics to which the nano calcium phosphate oligomer is applied are placed in an environment with a room temperature and a humidity of 75%-90% for 48-60 h.

[0024] Advantages

[0025] The present application provides a nano calcium phosphate oligomer for reinforcing cultural relics, a preparation method and application thereof. An ethanol solution of calcium chloride is prepared, arginine is added, and then triethylamine is added to the mixture, and phosphoric acid is added and stirred for 12-24 h to obtain the nano calcium phosphate oligomer. The synthesis method is simple and easy to operate. More importantly, the nano calcium phosphate oligomer synthesized by the method does not need to provide an additional calcium source for reinforcing cultural relics, and has no requirement for whether the reinforcing object contains a calcium source. After being applied to ancient murals and stone cultural relics, the nano calcium phosphate oligomer prepared by the present application has good permeability in both and is converted into poorly crystalline hydroxyapatite connected to each other within 48-60 h.

[0026] Compared with the prior art, the present application provides a simple preparation method of the nano calcium phosphate oligomer. In the synthesis process, arginine is modified on the surface of calcium phosphate so that it is dispersed in the solution to form nano particles (50-300 nm) without agglomeration. In terms of application, the reinforced cultural relic object does not necessarily contain a calcium source. After being applied to ancient murals and stone cultural relics, the nano calcium phosphate oligomer prepared by the present application has good permeability in the murals and stone cultural relics, which can reach centimeter level, and is converted into a film connected to each other within 48-60 h, thereby connecting the loose structures in the cultural relics to play a reinforcing role. The film is composed of poorly crystalline hydroxyapatite. Reinforcing strength tests show that the hardness and surface bonding strength of the ancient murals and stone cultural relics to which the material is applied are increased by 50%-80% and 4-6 times, respectively. Compared with the ancient murals and stone cultural relics reinforced by traditional ammonium dihydrogen phosphate, calcium chloride and ammonium dihydrogen phosphate, the hardness and surface bonding strength are comparable, but for ammonium dihydrogen phosphate, the cultural relic object containing a calcium source needs to be selected, and for calcium chloride and ammonium dihydrogen phosphate, the solution of calcium chloride has potential damage to the cultural relics, and the time process needs to sequentially apply calcium chloride and ammonium dihydrogen phosphate, thereby increasing the risk of damage to the cultural relics. In addition, the two methods of ammonium dihydrogen phosphate, calcium chloride and ammonium dihydrogen phosphate form sheet-shaped calcium phosphate with good crystallinity in the cultural relics, which is not conducive to reinforcement in the long term because a continuous film-shaped hydroxyapatite like the material of the present application is not formed. The nano calcium phosphate prepared by the present application has great application prospect in the reinforcement of cultural relics. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1It is a dynamic light scattering test result chart of nano calcium phosphate oligomer, the horizontal coordinate is particle size, and the vertical coordinate is particle size proportion. It can be seen from the chart that the nano calcium phosphate oligomer particle size range is 50-300nm, and the 80nm size particle has the most proportion (the vertex corresponds to the size). DETAILED DESCRIPTION

[0028] The application will be further described in combination with examples and drawings:

[0029] The application aims to provide a nano calcium phosphate oligomer for ancient cultural relic reinforcement and a preparation method thereof. The nano calcium phosphate oligomer is prepared by first configuring an ethanol solution of calcium chloride, then adding arginine, and finally adding triethylamine to the above mixture, adding phosphoric acid and stirring for 12-24h. The synthesis method is simple and easy to operate. More importantly, the nano calcium phosphate oligomer synthesized by the method does not need to provide an additional calcium source for cultural relic reinforcement, and has no requirement for whether the reinforcement object contains a calcium source. After being applied to ancient murals and stone cultural relics, it is found that the nano calcium phosphate oligomer prepared by the application has good permeability in both and is converted into a poorly crystalline hydroxyapatite connected to each other within 48-60h. Reinforcement strength test shows that the hardness and surface bonding strength of ancient murals and stone cultural relics to which the material is applied are increased by 50%-80% and 4-6 times, respectively. Compared with traditional ammonium dihydrogen phosphate, calcium chloride and ammonium dihydrogen phosphate, the hardness and surface bonding strength of ancient murals and stone cultural relics reinforced by the method are comparable. The material breaks through the limitation of cultural relic reinforcement objects and has good popularization prospect.

[0030] Preparation method steps:

[0031] Step one, configuration of calcium chloride ethanol solution, arginine aqueous solution and phosphoric acid ethanol solution: first, 2.2-4.4 grams of calcium chloride dihydrate is added to 50-100mL of ethanol to obtain a calcium chloride ethanol solution; 0.3-0.8g of arginine is added to 10mL of pure water to configure an arginine aqueous solution; 0.7mL-2.8mL of phosphoric acid solution is added to 10mL-40mL of ethanol to configure a phosphoric acid ethanol solution.

[0032] Step two, preparation of nano calcium phosphate oligomer: the arginine solution of step one is added dropwise to the calcium chloride ethanol solution to obtain a calcium chloride solution containing arginine; after completion, 50mL-100mL of triethylamine is added to the solution containing arginine; finally, the phosphoric acid ethanol solution is added dropwise to the mixed solution of triethylamine, arginine and calcium chloride, and stirred for 12-24h; after stirring is completed, the nano calcium phosphate oligomer is obtained by centrifugation and washing with an ethanol solution.

[0033] Application steps:

[0034] The prepared nano calcium phosphate oligomers are ultrasonically dispersed in ethanol to obtain an ethanol solution of nano calcium phosphate oligomers with a concentration of 10-20 mg / mL. The solution is sprayed on the surface of the ancient murals and stone artifacts until no absorption occurs, and then the excess solution on the surface is wiped off with absorbent cotton. Then the ancient murals and stone artifacts to which the nano calcium phosphate oligomers are applied are placed in an environment with a room temperature and a humidity of 75%-90% for 48-60 h.

[0035] Example One

[0036] First, 2.2 g of calcium chloride dihydrate is added to 50 mL of ethanol to obtain an ethanol solution of calcium chloride; 0.3 g of arginine is added to 10 mL of pure water to prepare an arginine aqueous solution; and 0.7 mL of a phosphoric acid solution is added to 10 mL of ethanol to prepare an ethanol solution of phosphoric acid. The arginine solution is added dropwise to the ethanol solution of calcium chloride to obtain a calcium chloride solution containing arginine; then 50 mL of triethylamine is added to the solution containing arginine; and finally, the ethanol solution of phosphoric acid is added dropwise to the mixed solution of triethylamine, arginine and calcium chloride, and stirred for 12 h; after stirring, the nano calcium phosphate oligomers are obtained by centrifugation and washing with an ethanol solution.

[0037] The ancient murals and stone artifacts are reinforced by the following method: the prepared nano calcium phosphate oligomers are ultrasonically dispersed in ethanol to obtain an ethanol solution of nano calcium phosphate oligomers with a concentration of 10 mg / mL. The solution is sprayed on the surface of the ancient murals and stone artifacts until no absorption occurs, and then the excess solution on the surface is wiped off with absorbent cotton. Then the ancient murals and stone artifacts to which the nano calcium phosphate oligomers are applied are placed in an environment with a room temperature and a humidity of 75% for 48 h.

[0038] The test results show that the nano calcium carbonate oligomers can be completely converted into continuous film-shaped hydroxyapatite in 50 h. For ancient murals, the nano calcium carbonate oligomers can increase the hardness by 80% and the adhesive strength by 5 times; for stone artifacts, the nano calcium carbonate oligomers can increase the hardness by 70% and the adhesive strength by 6 times. The hardness and adhesive strength of the ancient murals and stone artifacts to which ammonium dihydrogen phosphate, calcium chloride and ammonium dihydrogen phosphate are applied are comparable, but finally form sheet-shaped hydroxyapatite.

[0039] Example Two

[0040] First, 3.6 g of calcium chloride dihydrate was dissolved in 80 mL of ethanol to obtain a calcium chloride ethanol solution; 0.5 g of arginine was dissolved in 10 mL of pure water to obtain an arginine aqueous solution; 1.0 mL of phosphoric acid solution was added to 20 mL of ethanol to obtain a phosphoric acid ethanol solution. The arginine solution was added dropwise to the calcium chloride ethanol solution to obtain a calcium chloride solution containing arginine; after completion, 60 mL of triethylamine was added to the solution containing arginine; finally, the phosphoric acid ethanol solution was added dropwise to the mixed solution of triethylamine, arginine and calcium chloride, and stirred for 20 h; after completion of stirring, the nano calcium phosphate oligomer was obtained by centrifugation and washing with an ethanol solution.

[0041] Ancient wall paintings and stone cultural relics reinforcement method: the prepared nano calcium phosphate oligomer was ultrasonically dispersed in ethanol to obtain a nano calcium phosphate oligomer ethanol solution with a concentration of 15 mg / mL. The solution was sprayed on the surface of the ancient wall paintings and stone cultural relics until no absorption occurred, and then the excess solution on the surface was wiped off with absorbent cotton. Then the ancient wall paintings and stone cultural relics to which the nano calcium phosphate oligomer was applied were placed in an environment at room temperature and a humidity of 85% for 50 h.

[0042] The test results show that the nano calcium carbonate oligomer can be completely converted into continuous film-shaped hydroxyapatite in 50 h, and for ancient wall paintings, the nano calcium carbonate oligomer can increase the hardness by 80% and the bonding strength by 6 times; for stone cultural relics, the nano calcium carbonate oligomer can increase the hardness by 70% and the bonding strength by 6 times. The hardness and bonding strength of the ancient wall paintings and stone cultural relics to which ammonium dihydrogen phosphate, calcium chloride and ammonium dihydrogen phosphate were applied are comparable, but finally form sheet-shaped hydroxyapatite.

[0043] Example Three:

[0044] First, 3.6 g of calcium chloride dihydrate was dissolved in 80 mL of ethanol to obtain a calcium chloride ethanol solution; 0.5 g of arginine was dissolved in 10 mL of pure water to obtain an arginine aqueous solution; 1.0 mL of phosphoric acid solution was added to 20 mL of ethanol to obtain a phosphoric acid ethanol solution. The arginine solution was added dropwise to the calcium chloride ethanol solution to obtain a calcium chloride solution containing arginine; after completion, 60 mL of triethylamine was added to the solution containing arginine; finally, the phosphoric acid ethanol solution was added dropwise to the mixed solution of triethylamine, arginine and calcium chloride, and stirred for 20 h; after completion of stirring, the nano calcium phosphate oligomer was obtained by centrifugation and washing with an ethanol solution.

[0045] Ancient wall paintings, stone relics, and the like, are strengthened by spraying a solution of the nano calcium phosphate oligomers in ethanol onto the surface of the ancient wall paintings, stone relics, and the like, until the solution is no longer absorbed, and then wiping the surface with absorbent cotton to remove the excess solution. The ancient wall paintings and stone relics to which the nano calcium phosphate oligomers have been applied are then placed in an environment at room temperature and having a humidity of 90% for 60 hours.

[0046] The test results show that the nano calcium carbonate oligomers can completely transform into continuous film-shaped hydroxyapatite in 60 hours. For ancient wall paintings, the nano calcium carbonate oligomers can increase the hardness of the ancient wall paintings by 80% and increase the adhesive strength by 5 times. For stone relics, the nano calcium carbonate oligomers can increase the hardness of the stone relics by 80% and increase the adhesive strength by 6 times. The hardness and adhesive strength of the ancient wall paintings and stone relics to which ammonium dihydrogen phosphate, calcium chloride, and ammonium dihydrogen phosphate have been applied are comparable, but the final product is flaky hydroxyapatite.

[0047] Example Four

[0048] First, 4.4 g of calcium chloride dihydrate is dissolved in 100 mL of ethanol to obtain a solution of calcium chloride in ethanol; 0.8 g of arginine is dissolved in 10 mL of pure water to obtain an aqueous arginine solution; and 2.8 mL of a phosphoric acid solution is dissolved in 40 mL of ethanol to obtain a solution of phosphoric acid in ethanol. The solution of arginine in ethanol is added dropwise to the solution of calcium chloride in ethanol to obtain a solution of calcium chloride containing arginine; after completion, 100 mL of triethylamine is added to the solution containing arginine; and finally, the solution of phosphoric acid in ethanol is added dropwise to the mixed solution of triethylamine, arginine, and calcium chloride, and stirred for 24 hours; after completion of stirring, the nano calcium phosphate oligomers are obtained by centrifugation and washing with an ethanol solution.

[0049] Ancient wall paintings, stone relics, and the like, are strengthened by spraying a solution of the nano calcium phosphate oligomers in ethanol onto the surface of the ancient wall paintings, stone relics, and the like, until the solution is no longer absorbed, and then wiping the surface with absorbent cotton to remove the excess solution. The ancient wall paintings and stone relics to which the nano calcium phosphate oligomers have been applied are then placed in an environment at room temperature and having a humidity of 90% for 60 hours.

[0050] The test results show that the nano calcium carbonate oligomers can completely transform into continuous film-shaped hydroxyapatite in 60 hours. For ancient wall paintings, the nano calcium carbonate oligomers can increase the hardness of the ancient wall paintings by 80% and increase the adhesive strength by 5 times. For stone relics, the nano calcium carbonate oligomers can increase the hardness of the stone relics by 80% and increase the adhesive strength by 5 times. The hardness and adhesive strength of the ancient wall paintings and stone relics to which ammonium dihydrogen phosphate, calcium chloride, and ammonium dihydrogen phosphate have been applied are comparable, but the final product is flaky hydroxyapatite.

[0051] While the application has been described in detail and with reference to specific preferred embodiments thereof, it will be apparent to one skilled in the art that various modifications and alternatives can be employed without departing from the spirit and scope of the application. Accordingly, the scope of the application should be determined by the appended claims and their equivalents.

Claims

1. A method for the preparation of nano-sized calcium phosphate oligomers for the reinforcement of cultural heritage objects, characterized by The steps are as follows: Step 1, configuration of calcium chloride ethanol solution, arginine aqueous solution, ethanol solution of phosphoric acid: Calcium chloride dihydrate is obtained in ethanol to obtain calcium chloride ethanol solution A; Arginine is added to pure water to prepare arginine aqueous solution B; Phosphoric acid solution is added to ethanol to prepare ethanol solution C of phosphoric acid; The preparation ratio of the calcium chloride ethanol solution A is 2.2-4.4 grams of calcium chloride dihydrate to 50-100 mL of ethanol; The preparation ratio of the arginine aqueous solution B is 0.3-0.8 grams of arginine to 10 mL of pure water; Step 2, preparation of nano calcium phosphate oligomer: Step 2.1: arginine aqueous solution B is added dropwise to calcium chloride ethanol solution A to obtain calcium chloride solution D containing arginine; Step 2.2: triethylamine is added to calcium chloride solution D containing arginine to obtain solution E containing triethylamine; Step 2.3: phosphoric acid ethanol solution C is added dropwise to solution E containing triethylamine and stirred; after stirring, nano calcium phosphate oligomer is obtained by centrifugation and washing with ethanol solution.

2. The method for preparing the nano-sized calcium phosphate oligomers for reinforcing cultural relics according to claim 1, characterized in that: The preparation ratio of the ethanol solution C of phosphoric acid is 0.7 mL-2.8 mL of phosphoric acid solution to 10 mL-40 mL of ethanol.

3. The method for preparing nano-calcium phosphate oligomers for cultural relic reinforcement according to claim 1, characterized in that: The triethylamine added in step 2.2 is 50 mL-100 mL.

4. The method for preparing nano-calcium phosphate oligomers for cultural relic reinforcement according to claim 1, characterized in that: The stirring time in step 2.3 when adding the ethanol solution C of phosphoric acid is 12-24 h.

5. Use of the nano-sized calcium phosphate oligomer obtained by the production method according to any one of claims 1 to 4, characterized in that: For the reinforcement of ancient murals and stone cultural relics, nano calcium phosphate oligomer is ultrasonically dispersed in ethanol to obtain a nano calcium phosphate oligomer ethanol solution with a concentration of 10-20 mg / mL; the solution is sprayed on the surface of ancient murals and stone cultural relics until no absorption occurs, and then the excess solution on the surface is wiped off with absorbent cotton; then the ancient murals and stone cultural relics to which the nano calcium phosphate oligomer has been applied are placed in an environment with a room temperature and a humidity of 75%-90% for 48-60 h.

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