Ancient book paper protective agent containing nano-graphene and preparation method of ancient book paper protective agent

Abstract

The invention provides a nano-graphene-containing ancient book paper protective agent and a preparation method thereof, the protective agent is composed of nano-graphene, an alkaline substance, gelatin and a solvent according to a certain ratio, the alkaline substance is loaded on the nano-graphene and accords with the gelatin mechanism, and the nano-graphene-containing ancient book paper protective agent is prepared. The multifunctional integrated protection of efficient deacidification of ancient book paper, remarkable enhancement of mechanical strength, aging resistance and the like is realized. The product is good in dispersity and high in compatibility, can be constructed in modes of spraying, dipping and the like, is simple and convenient to operate, and is suitable for large-scale repair and long-term storage of precious ancient books.

Description

Technical Field

[0001] This invention relates to the field of paper cultural relic preservation materials, specifically to a paper preservation agent for ancient books containing nano-graphene and its preparation method. Background Technology

[0002] Ancient books are mostly made using traditional handmade papermaking techniques, with plant fibers (such as hemp, bamboo, and cotton) as their main component. Due to their naturally porous structure and chemical composition, these papers are prone to various irreversible degradation reactions during long-term preservation. Specifically, acidic substances within the paper, such as organic acids produced by lignin degradation and sulfuric acid formed from the adsorption of acidic gases like sulfur dioxide from the air, catalyze the hydrolysis of cellulose molecules, leading to a decrease in the degree of polymerization and a drop in the paper's pH. This manifests as yellowing, brittleness, and even powdering of the paper, resulting in a severe loss of mechanical strength. Furthermore, under the influence of light and oxygen, the fibers undergo oxidation, further yellowing the paper and causing the ink to fade, severely impacting the readability and preservation of the documents. These acidification, oxidation, and hydrolysis processes reinforce each other, exacerbating the deterioration of ancient books and making their conservation and restoration particularly urgent and of significant cultural value.

[0003] Currently, methods for preserving ancient book paper mainly focus on two aspects: deacidification and reinforcement. Existing technologies often employ dispersions of alkaline nanomaterials, such as nano-calcium hydroxide and magnesium hydroxide, to impregnate or spray the paper, neutralizing acidic substances and reserving alkali reserves to delay subsequent acidification. However, these methods have significant limitations: First, nanoparticles tend to aggregate in solvents, resulting in poor permeability and uniform distribution among paper fibers, affecting the deacidification effect and potentially creating areas of excessive alkalinity that accelerate the alkaline degradation of cellulose. Second, their functions are too singular; most materials only focus on chemical deacidification and cannot simultaneously address the comprehensive problems of decreased paper mechanical strength and insufficient anti-aging properties. Furthermore, some introduced alkaline substances or polymer reinforcing agents may have poor compatibility with the original paper components, altering the paper's color, texture, or breathability, and are difficult to remove, posing irreversible risks to subsequent restoration work.

[0004] Therefore, there is an urgent need in this field to develop a new type of multifunctional protective material that can not only efficiently and uniformly neutralize acidic substances, but also significantly enhance the mechanical properties of paper, and possess anti-aging and original appearance maintenance properties, so as to achieve comprehensive, safe and sustainable protection for ancient book paper. Summary of the Invention

[0005] The purpose of this invention is to provide a protective agent for ancient book paper containing nano-graphene and its preparation method. By loading alkaline substances onto nano-graphene and combining them with biological substrates such as gelatin, a multifunctional protective agent for ancient book paper is achieved, which includes deacidification, reinforcement and anti-aging. It has advantages such as good dispersibility, high compatibility and strong controllability, and is suitable for large-scale restoration and electronic protection of precious ancient books.

[0006] To achieve the above objectives, the present invention proposes the following technical solution:

[0007] A paper preservative for ancient books containing nano-graphene, comprising the following components in parts by weight:

[0008] Nanographene: 0.1-1.0 parts;

[0009] Alkaline substances: 1.0-3.0 parts;

[0010] Gelatin: 0.5-2.5 parts;

[0011] Solvent: 90.0-98.0 parts;

[0012] The nano-graphene and the alkaline substance are combined in a gel state through physical or chemical means to form a load structure.

[0013] As a preferred embodiment of the present invention, the nano-graphene is at least one of graphene oxide or epoxy graphene oxide.

[0014] As a preferred embodiment of the present invention, the alkaline substance is calcium hydroxide, magnesium hydroxide, or a mixture of both.

[0015] As a preferred embodiment of the present invention, the composition further comprises at least one of the following: 0.01-0.5 parts by weight of chitosan, 0.05-0.2 parts by weight of antioxidant, 0.01-0.1 parts by weight of ultraviolet absorber, and 1.0-5.0 parts by weight of plasticizer.

[0016] As a preferred embodiment of the present invention, the protective agent is in the form of a solution with a viscosity of less than 100 cP, a paste with a viscosity of 500-1000 cP, or an emulsion.

[0017] As a preferred embodiment of the present invention, the protective agent is suitable for application to the surface of ancient book paper by spraying, impregnation or scraping.

[0018] This invention also provides a method for preparing a paper preservative for ancient books containing nano-graphene, comprising the following steps:

[0019] (1) Disperse the nano-graphene in a partial solvent to form a nano-graphene dispersion;

[0020] (2) Preparation of gels or solutions of alkaline substances;

[0021] (3) Mix the nano-graphene dispersion obtained in step (1) with the alkaline substance obtained in step (2), and load the alkaline substance onto the nano-graphene through mechanical treatment to form a loaded structure;

[0022] (4) Dissolve the gelatin in the remaining solvent to form a gelatin solution;

[0023] (5) The loaded structure obtained in step (3) is mixed with the gelatin solution obtained in step (4) and optional additives, and homogenized to obtain the protective agent.

[0024] As a preferred technical solution of the present invention, the preparation of the alkaline substance gel in step (2) is carried out by gas phase diffusion method, which is to prepare the alkaline solution by gas phase diffusion in an atmosphere of ammonia and carbon dioxide.

[0025] As can be seen from the above technical solutions, the technical solutions of the present invention provide a protective agent for ancient book paper containing nano-graphene and its preparation method, which has the following beneficial effects compared with the prior art:

[0026] The material exhibits high dispersion stability; graphene and gelatin synergistically prevent agglomeration and ensure uniform penetration; alkaline substances provide slow-release deacidification, graphene enhances mechanical properties, and anti-aging components inhibit degradation; the gelatin film is flexible and easy to remove; the graphene concentration is controllable, preventing color changes; the gas-phase diffusion method operates at room temperature and pressure, resulting in low energy consumption and suitability for large-scale production. These findings demonstrate that the material of this invention is superior to traditional protective agents in deacidification, reinforcement, and anti-aging, making it suitable for large-scale restoration and electronic preservation of ancient books and paper.

[0027] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the described embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0029] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" mean that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof.

[0030] This invention provides a protective agent for ancient book paper containing nano-graphene, which is composed of the following components in parts by weight: nano-graphene: 0.1-1.0 parts; alkaline substance: 1.0-3.0 parts; gelatin: 0.5-2.5 parts; solvent: 90.0-98.0 parts; and further contains at least one of the following: 0.01-0.5 parts of chitosan, 0.05-0.2 parts of antioxidant, 0.01-0.1 parts of ultraviolet absorber, and 1.0-5.0 parts of plasticizer by weight of the total composition.

[0031] The nano-graphene and the alkaline substance are combined in a gel state through physical or chemical means to form a load structure, wherein the nano-graphene is used as a carrier and the alkaline substance is used as a loading material to modify the graphene.

[0032] Specifically, the nanographene is at least one of graphene oxide or epoxy graphene oxide.

[0033] Specifically, the alkaline substance is calcium hydroxide, magnesium hydroxide, or a mixture of both. These two alkaline substances are readily available and have a mild alkalinity, thus avoiding excessive alkalization of the ancient book paper.

[0034] In this invention, the protective agent is not limited to a single type; it can be a solution with a viscosity of less than 100 cP, a paste with a viscosity of 500-1000 cP, or an emulsion. The appropriate protective agent form can be formulated according to the specific restoration method and the actual condition of the ancient book paper. The application methods of the protective agent are also varied; a suitable method can be selected according to the specific restoration plan, such as applying it to the surface of the ancient book paper by spraying, impregnation, or scraping.

[0035] The solvent can be selected as a pure solvent or a mixed solvent according to the specific repair requirements. Pure solvents include deionized water and pure ethanol, while mixed solvents include a mixed solution of the two in a certain ratio, such as 1:1. Different components can be dissolved in different solvents, or in the same solvent of different concentrations, or in a mixed solvent of different ratios.

[0036] Example 1: Basic Nano-Graphene / Gelatin Deacidification and Consolidation Solution

[0037] 0.5 parts graphene oxide nanosheets; 2.0 parts calcium hydroxide gel (by weight of calcium hydroxide); 1.5 parts bio-grade gelatin; 96.0 parts deionized water.

[0038] The graphene oxide nanosheets used in this embodiment are rich in oxygen-containing functional groups such as carboxyl and epoxy groups, exhibiting strong hydrophilicity and readily dispersible in aqueous solvents to form stable colloids. Their porous structure results in a surface area ≥500 m². 2 / g, with a pore size of 1-10nm, it can efficiently load alkaline substances and bind to paper fibers through hydrogen bonds, thereby enhancing the mechanical strength of the paper.

[0039] Preparation method:

[0040] (1) Preparation of graphene oxide dispersion: Add graphene oxide nanosheets to 20 mL of deionized water and sonicate for 30 minutes at 300 W to obtain a nano-graphene dispersion.

[0041] (2) Preparation of calcium hydroxide gel:

[0042] 0.1 g of calcium oxide powder (nanoscale) was added to an open container containing 50 mL of pure ethanol and ultrasonically dispersed for 10 minutes. The open container with dispersed calcium oxide was then placed in a sealed desiccator. Inside the desiccator, a beaker containing solid ammonium bicarbonate was placed, along with desiccants such as silica gel for moisture absorption, placed separately next to the beaker and the open container. Ammonium bicarbonate released ammonia and carbon dioxide gases in a molar ratio of 1:3. The mixed gases diffused into the open container and reacted with the calcium oxide over 12 hours, forming an amorphous calcium hydroxide gel with a concentration of approximately 1.9 g / L.

[0043] (3) Mix the nano-graphene dispersion with calcium hydroxide gel and stir slowly for 30-60 minutes to form a loaded structure.

[0044] (4) Preparation of gelatin solution: Dissolve gelatin in the remaining deionized water at 60°C and stir until completely dissolved.

[0045] (5) Mix the gelatin solution with the supported structure solution and continue stirring for 1 hour. Adjust the pH of the mixed solution dropwise to 8.5±0.5 with a 0.1mol / L dilute acetic acid solution to obtain the basic nano-graphene / gelatin deacidification protectant.

[0046] The nano-graphene oxide in this embodiment has a porous structure and a specific surface area ≥500 m². 2 / g, far exceeding traditional carriers such as nanocellulose (≤300m 2(e.g.) etc., as carriers, have a larger loading capacity, and the supported calcium hydroxide can slowly release OH. - It neutralizes acidic substances; simultaneously, graphene's strength (typically 130 GPa) is significantly superior to cellulose (≤2 GPa), and its surface oxygen-containing functional groups form hydrogen bonds with the hydroxyl groups of paper fibers, significantly enhancing the tensile strength of paper. Calcium hydroxide gel prepared by gas-phase diffusion has an amorphous structure, making it easier to load in large quantities into the micropores of graphene oxide compared to granular calcium hydroxide. It exhibits higher activity and more uniform distribution within the micropores, resulting in more uniform deacidification. Gelatin, as a natural matrix, is used to improve the dispersibility of nano-graphene oxide and alkaline substances, forming a flexible protective film and enhancing paper toughness.

[0047] Nano-graphene oxide and gelatin jointly construct a three-dimensional network structure, with alkali agents embedded within it to achieve controlled release. At the same time, the UV absorption capacity of nano-graphene oxide reduces photoaging, with its absorption peak at approximately 270 nm.

[0048] Example 2

[0049] Reduced graphene oxide 0.3 parts; magnesium hydroxide gel 1.5 parts (by mass of magnesium hydroxide); gelatin 1.0 part; chitosan 0.5 parts; ethanol / water mixed solvent (v / v=1:1) 96.7 parts.

[0050] Preparation method:

[0051] (1) Preparation of reduced graphene oxide dispersion:

[0052] Reduced graphene oxide is produced by using graphene oxide. It has extremely low oxygen content, restores conductivity, and has high transparency. It can prevent dark colors from altering the original appearance of ancient books and paper. In addition, its hydrophobicity is enhanced, making it ideal for applications requiring moisture protection.

[0053] Reduced graphene oxide was added to pure ethanol and ultrasonically dispersed for 20 minutes at a power of 250W to obtain a reduced graphene oxide dispersion.

[0054] (2) Preparation of magnesium hydroxide gel:

[0055] 0.08 g of magnesium chloride was dissolved in 50 mL of pure ethanol and dispersed by ultrasonication. Then, in the same manner as the preparation method of calcium hydroxide gel in Example 1, the above magnesium chloride dispersion was placed in a desiccator and reacted with solid ammonium bicarbonate for 12 hours to generate magnesium hydroxide gel with a concentration of about 1.6 g / L.

[0056] (3) Mix the reduced graphene oxide dispersion with magnesium hydroxide gel and stir slowly for 30-60 minutes to form a loaded structure.

[0057] (4) Preparation of gelatin base solution: Dissolve gelatin and chitosan in deionized water at 50°C and stir to form a homogeneous solution.

[0058] (5) Mix the gelatin base solution with the loaded structure solution, stir for 2 hours, remove the aggregated particles with a microporous filter membrane, and obtain a transparent protective agent.

[0059] Reduced graphene oxide retains the strength of graphene, and its high transparency preserves the original appearance of the paper, preventing dark colors from altering the original appearance of ancient books. Compared to cellulose, graphene is conductive, reducing static electricity buildup on the paper and improving the clarity of scanned images. Magnesium hydroxide, with its mild alkalinity and slow-release deacidification, synergistically enhances the paper's durability with reduced graphene oxide. Chitosan and gelatin work together to enhance adhesion, forming a reversible protective layer that is easy to remove later. The composite film of reduced graphene oxide, chitosan, and gelatin provides hydrophobicity with a contact angle ≥90°, preventing moisture intrusion, while magnesium hydroxide continuously neutralizes acids.

[0060] Example 3

[0061] 1.0 part of nano-sized porous graphene oxide microspheres (loaded with alkaline substances); 2.5 parts of calcium hydroxide / magnesium hydroxide mixture (molar ratio of 1:1); 2.0 parts of gelatin; 0.1 part of antioxidant (vitamin E); 0.05 parts of ultraviolet absorber (benzotriazole); 5.0 parts of plasticizer (glycerin); 89.35 parts of deionized water.

[0062] Preparation method:

[0063] (1) Add graphene oxide nanosheets to 10 mL of deionized water and ultrasonically disperse for 30 minutes (power 300W) to obtain a uniform dispersion with a concentration of about 5 mg / mL.

[0064] (2) Alkaline gel pretreatment: Calcium hydroxide and magnesium hydroxide gels were prepared by the methods in Examples 1 and 2, respectively, and mixed evenly by molar ratio of 1:1 to obtain mixed alkaline gel.

[0065] (3) The graphene oxide dispersion and the mixed alkaline gel were mixed in a certain proportion and loaded using a wet ball milling process. The ball milling conditions were: a planetary ball mill was used, with zirconia grinding balls of 3-5 mm diameter, a ball-to-material mass ratio of 10:1, a rotation speed of 300 rpm, and a milling time of 2 hours. After ball milling, the nanoscale porous graphene oxide microspheres loaded with alkaline substances were obtained by spray drying.

[0066] (4) Dissolve gelatin and glycerin in the remaining deionized water, heat to 50°C, and stir until the solution is homogeneous. Add supported graphene oxide microspheres, antioxidants and ultraviolet absorbers, homogenize and emulsify using a high-speed homogenizer, and adjust the viscosity to 500-1000 cP (using a Brookfield viscometer) to obtain a paste-like protective agent.

[0067] This embodiment achieves long-lasting deacidification by loading dual alkali agents onto microspheres with their high specific surface area; the microspheres fill the pores of the paper, increasing its density. Antioxidants and UV absorbers inhibit oxidation and photodegradation, synergizing with the shielding effect of graphene oxide. Glycerin and gelatin improve the flexibility of the paste, preventing paper embrittlement. Graphene oxide and gelatin form a core-shell structure, integrating the triple functions of alkali agent slow release, anti-aging, and mechanical reinforcement.

[0068] The protective agents obtained in Examples 1-3 were applied to ancient book paper samples with the same degree of deterioration (pH=4.5, tensile strength=15MPa, folding endurance=5 times) and subjected to accelerated aging tests (85℃, 65%RH, for 30 days). The test results of key performance indicators are shown in Table 1 below.

[0069] The testing method is as follows:

[0070] pH value: cold water extraction method (GB / T 1545).

[0071] Tensile strength: Universal testing machine (GB / T 12914).

[0072] Folding endurance: MIT folding endurance tester (GB / T 457).

[0073] Color difference: Colorimeter (CIE Lab standard, less than 2 is considered imperceptible change).

[0074] UV shielding rate: UV-Vis spectrophotometer, wavelength 200-400nm.

[0075] Table 1

[0076] index Untreated paper Example 1 Example 2 Example 3 pH value 4.5 7.4 7.6 7.8 Flexural endurance (times) 5 20 18 23 Color difference - 1.8 1.5 1.9 UV shielding efficiency (300nm, %) - 85% 88% 90% Tensile strength (MPa) 15.0 21.8 20.7 22.5

[0077] As can be seen from the data in Table 1, all three embodiments provided by the present invention can effectively improve the various properties of ancient book paper, but the focus is different, which reflects the flexibility of the formulation design.

[0078] 1. Example 1 is a basic graphene oxide + gelatin solution, which shows outstanding enhancement in mechanical properties, with tensile strength increased by 45.3% and folding endurance increased by 300%. This is mainly due to the excellent structural strength of graphene oxide and the strong three-dimensional network formed by paper fibers. This example is a preferred solution for applications requiring high-strength reinforcement.

[0079] 2. Example 2 has unique advantages in preserving the original appearance of ancient book paper, exhibiting minimal color difference and high solution transparency, with almost no alteration to the paper's visual appearance after treatment. Simultaneously, its antistatic properties facilitate subsequent electronic scanning. This example is suitable for precious ancient books where extremely high fidelity in appearance is required.

[0080] 3. Example 3 demonstrates the most comprehensive protective effect, especially in tensile strength, flexural endurance, and UV shielding efficiency, which are all at the highest levels. This is attributed to the synergistic effect of the slow-release action of the graphene oxide porous microspheres as a carrier and various anti-aging additives. This example is the best choice for dealing with severe degradation and requiring comprehensive protection.

[0081] In summary, this invention has successfully prepared a variety of high-performance paper preservatives for ancient books through the innovative combination of the core material, nano-graphene, with alkaline gel and gelatin substrate. Compared with traditional materials using nano-cellulose as a carrier, this invention has achieved significant technological progress in terms of mechanical reinforcement, functional integration (combining deacidification, reinforcement, anti-aging, and antistatic properties), and the special protective mechanism brought about by the unique properties of graphene, such as high specific surface area, strength, and conductivity. It effectively solves the technical problems of existing protective materials, such as limited functionality, poor compatibility, and potential alteration of the original paper appearance.

[0082] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A paper preservative for ancient books containing nano-graphene, characterized in that, Composed of the following components in parts by weight: Nanographene: 0.1-1.0 parts; Alkaline substances: 1.0-3.0 parts; Gelatin: 0.5-2.5 parts; Solvent: 90.0-98.0 parts; The nano-graphene and the alkaline substance are combined in a gel state through physical or chemical means to form a load structure.

2. The ancient book paper preservative containing nano-graphene according to claim 1, characterized in that, The nanographene is at least one of graphene oxide or epoxy graphene oxide.

3. The ancient book paper preservative containing nano-graphene according to claim 1, characterized in that, The alkaline substance is calcium hydroxide, magnesium hydroxide, or a mixture of both.

4. The ancient book paper preservative containing nano-graphene according to claim 1, characterized in that, It also contains at least one of the following: 0.01-0.5 parts by weight of chitosan, 0.05-0.2 parts by weight of antioxidant, 0.01-0.1 parts by weight of ultraviolet absorber, and 1.0-5.0 parts by weight of plasticizer.

5. The ancient book paper preservative containing nano-graphene according to claim 1, characterized in that, The protective agent is in the form of a solution with a viscosity of less than 100 cP, a paste with a viscosity of 500-1000 cP, or an emulsion.

6. The ancient book paper preservative containing nano-graphene according to claim 1, characterized in that, The protective agent is suitable for application to the surface of ancient book paper by spraying, dipping or scraping.

7. A method for preparing a paper preservative for ancient books containing nano-graphene as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Disperse the nano-graphene in a partial solvent to form a nano-graphene dispersion; (2) Preparation of gels or solutions of alkaline substances; (3) Mix the nano-graphene dispersion obtained in step (1) with the alkaline substance obtained in step (2), and load the alkaline substance onto the nano-graphene through mechanical treatment to form a loaded structure; (4) Dissolve the gelatin in the remaining solvent to form a gelatin solution; (5) The loaded structure obtained in step (3) is mixed with the gelatin solution obtained in step (4) and optional additives, and homogenized to obtain the protective agent.

8. The ancient book paper preservative containing nano-graphene according to claim 7, characterized in that, The preparation of the alkaline gel in step (2) is carried out by gas phase diffusion method, in which the alkaline solution is prepared by gas phase diffusion in an atmosphere of ammonia and carbon dioxide gas.