A hydrogel loaded with CM dispersion, its preparation method and application

Abstract

This invention belongs to the field of paper cultural relic preservation technology, specifically relating to a hydrogel loaded with C-M dispersion, its preparation method, and its application. The preparation method includes the following steps: preparing an aqueous solution of sodium carboxymethyl cellulose, stirring the solution until it becomes clear and transparent; preparing a nano-magnesium hydroxide ethanol dispersion; mixing the two solutions in equal volumes and stirring until homogeneous to obtain a C-M dispersion; taking low-acyl gellan gum, gelatin, and glycerol, adding distilled water, swelling for 30 minutes, adding calcium acetate to obtain a hydrogel solution; mixing the C-M dispersion and the hydrogel solution, stirring until homogeneous, and heating in a microwave oven for 3-5 minutes until the solution becomes clear and transparent; transferring the solution to a mold while hot, and cooling to obtain a hydrogel loaded with C-M dispersion.

Description

Technical Field

[0001] This invention belongs to the field of paper cultural relic protection technology, specifically relating to a hydrogel loaded with CM dispersion, its preparation method and application. Background Technology

[0002] Paper artifacts are an important part of global cultural heritage, serving as carriers of art and cultural heritage and bearing immense historical and cultural value. However, long-term exposure to the environment, influenced by their inherent properties and external environmental factors, often leads to irreversible damage, manifesting as acidification, embrittlement, aging, crumbling, decay, and mold growth. Acidification, the accumulation of acidic substances during preservation, is the primary cause of paper deterioration. Under acidic conditions, the glycosidic bonds in paper fibers break, reducing fiber polymerization and consequently lowering the paper's mechanical strength. Factors contributing to the acidification of paper artifacts include: First, the addition of acidic substances such as alum during papermaking, and the presence of lignin in the raw materials themselves, which produces acidic substances through oxidation and hydrolysis. Second, long-term storage exposes the paper to temperature, humidity, light, and gases such as chlorides, nitrogen oxides, and carbon oxides in the air, accelerating acidification. Third, residues of pigments, inks, or chemicals used in printing, processing, and restoration processes can also contribute to the acidification of paper artifacts. Taking the early 20th-century newspapers in the Ancient Books Collection Room of Liaoning University as an example, during the storage process, affected by its own factors and various environmental factors, the paper turned yellow and became brittle, and shed a lot of residue. After testing, the pH of the collected residue fragments was 4.19, which is already at a severely acidified level. Therefore, the deacidification and protection of paper cultural relics is imminent.

[0003] In recent years, nanotechnology has been increasingly applied to the field of deacidification. For example, Wang Heyun et al. prepared nano-magnesium hydroxide and applied it to the deacidification treatment of paper artifacts. The deacidification effect of nano-magnesium hydroxide on paper artifacts was well characterized by tensile strength and paper surface pH. The tensile strength was stable after deacidification, indicating that nano-magnesium hydroxide can extend the preservation period of books, documents, and paper artifacts. However, since nanoparticles are slightly soluble in organic solvents such as water and anhydrous ethanol, this invention considers using sodium carboxymethyl cellulose, a natural polymer, to encapsulate the nano-magnesium hydroxide ethanol dispersion to obtain a CM dispersion. However, directly applying the CM dispersion to the paper surface, allowing it to come into direct contact with the paper, although it can achieve the effect of deacidification and reinforcement, after natural drying, the paper surface appears to be covered with a thin film, with a noticeably whiter color, curled edges, and increased paper thickness and weight. Microscopically, under a 10x objective optical microscope, many large and small, unevenly distributed particles are found filling the gaps in the paper fibers, which undoubtedly affects the paper's transparency, original texture, and flexibility. Summary of the Invention

[0004] The purpose of this invention is to provide a technical solution with good safety, which can avoid the adverse effects of direct contact between CM dispersion and paper on the paper's transparency, gloss, flexibility, and other properties, while simultaneously achieving deacidification and reinforcement of paper artifacts. Nano-magnesium hydroxide and sodium carboxymethyl cellulose are used as effective components for deacidification and reinforcement; gellan gum is used as the substrate of the hydrogel carrier; calcium acetate is used as a crosslinking agent to promote the transformation of the hydrogel from a soluble state to a gelled state; gelatin and glycerin are used as water-locking agents to synergistically control the amount of water released when the hydrogel contacts the paper. This prepares a hydrogel carrier capable of loading CM dispersion. Then, CM dispersion is added to the hydrogel carrier at volume ratios of 2:8, 3:7, 4:6, and 1:1 to obtain a hydrogel loaded with CM dispersion, which is then applied to the surface of acidified paper.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A hydrogel loaded with CM dispersion, the preparation method of which includes the following steps:

[0006] 1) Preparation of CM dispersion: Prepare sodium carboxymethyl cellulose aqueous solution and stir the solution until it is clear and transparent; prepare nano magnesium hydroxide ethanol dispersion; mix the two solutions in equal volumes and stir evenly.

[0007] 2) Preparation of hydrogel solution: Take low-acyl gellan gum, gelatin, and glycerol, add distilled water, swell for 30 min, add calcium acetate to obtain hydrogel solution;

[0008] 3) Preparation of hydrogel loaded with CM dispersion: Mix the CM dispersion and hydrogel solution, stir evenly, heat in a microwave oven for 3-5 minutes until the solution becomes clear and transparent, transfer it to a mold while hot, and use after cooling.

[0009] In the above-mentioned hydrogel loaded with CM dispersion, in step 1), the concentration of sodium carboxymethyl cellulose solution is 2-16 g / L; and the concentration of nano magnesium hydroxide ethanol dispersion is 8-16 g / L.

[0010] In the above-mentioned hydrogel loaded with CM dispersion, in step 2), the hydrogel solution contains a low-acyl gellan gum concentration of 10-30 g / L, a gelatin concentration of 5-30 g / L, a calcium acetate concentration of 0.2-1.2 g / L, and a glycerol volume fraction of 2.5-15%.

[0011] In step 3) of the above-mentioned hydrogel loaded with CM dispersion, the CM dispersion and the hydrogel solution are mixed at volume ratios of 2:8, 3:7, 4:6, and 1:1.

[0012] In the above-mentioned hydrogel loaded with CM dispersion, step 3) involves heating for 3-5 minutes at a temperature of 85°C.

[0013] The above-mentioned hydrogel loaded with CM dispersion is used in the deacidification and reinforcement of paper cultural relics.

[0014] The above-mentioned hydrogel loaded with CM dispersion is used in the application of paper cultural relics after acid reversion.

[0015] The present invention has the following beneficial effects:

[0016] In this invention, a hydrogel loaded with a CM dispersion is applied to the paper surface. Compared to directly applying the CM dispersion to the paper surface, this significantly shortens the contact time between the CM dispersion and the paper. The hydrogel loaded with the CM dispersion achieves deacidification in just 5-40 minutes. After deacidification, the hydrogel loaded with the CM dispersion can be completely peeled off from the paper surface without any residue. The hydrogel loaded with the CM dispersion is highly operable; hydrogels of different sizes and shapes can be prepared according to the morphology of the acidified sample. Under optical microscopy, it is observed that after the hydrogel loaded with the CM dispersion deacidifies the paper, no large particles remain in the gaps between the paper fibers (e.g., ...). Figure 2 As shown in the figure, this avoids the adverse effects of direct contact between the CM dispersion and the paper on various properties such as transparency, gloss, and whiteness. Furthermore, the hydrogel loaded with the CM dispersion used in this invention can achieve deacidification and reinforcement effects when applied to acidified paper, paper subjected to dry heat aging, and paper subjected to UV aging. Moreover, the deacidification and reinforcement effect is significantly improved compared to using single-component AGW, CM, or GG. Even if acid reversion occurs after deacidification, it still exhibits a significant reinforcement effect. Attached Figure Description

[0017] Figure 1 Flowchart for the preparation of hydrogels loaded with CM dispersion.

[0018] Figure 2 Microscopic images of paper fiber structure before and after deacidification treatment for each group. Among them, Ctrl is paper without deacidification treatment, AGW is paper after treatment with sizing solution, GG is paper after hydrogel treatment alone, CM is paper after treatment with CM dispersion, and GG-CM is paper after hydrogel treatment with CM dispersion.

[0019] Figure 3 The effects of different treatment conditions on the deacidification of paper before and after aging are shown in the figures.

[0020] Figure 4 Images showing the effects of different treatment conditions on paper reinforcement before and after aging.

[0021] Figure 5 Images showing the effects of different treatment conditions on the reinforcement of paper after acid reversion before and after aging. Detailed Implementation

[0022] Example 1: Preparation of hydrogels loaded with CM dispersion

[0023] (1) Preparation of CM dispersion: 16g of sodium carboxymethyl cellulose was placed in a beaker, and 1000ml of distilled water was added to prepare a sodium carboxymethyl cellulose solution with a concentration of 16g / L. The solution was stirred until clear and transparent. 16g of nano-magnesium hydroxide was placed in a beaker, and 1000ml of anhydrous ethanol was added. The mixture was stirred on a magnetic stirrer for 40min to prepare a nano-magnesium hydroxide ethanol dispersion with a concentration of 16g / L. The two solutions were mixed in equal volumes and stirred evenly to prepare a CM dispersion with a sodium carboxymethyl cellulose concentration of 8g / L and a nano-magnesium hydroxide concentration of 8g / L.

[0024] (2) Preparation of hydrogel solution: Take 20g of low acyl gellan gum, 20g of gelatin and 100ml of glycerol and put them in a beaker. Add 900ml of distilled water and let it swell for 30min. Add 0.4g of calcium acetate to prepare a hydrogel solution with low acyl gellan gum concentration of 20g / L, gelatin concentration of 20g / L, calcium acetate concentration of 0.4g / L and glycerol volume fraction of 10%.

[0025] (3) Preparation of hydrogel loaded with CM dispersion: Mix CM dispersion and hydrogel solution at a volume ratio of 1:1, stir evenly, put in microwave oven, heat at 85°C for 3-5 minutes until the solution is clear and transparent, transfer to mold while hot, and use after cooling.

[0026] Example 2: Application of hydrogels loaded with CM dispersion in the deacidification and consolidation of paper artifacts

[0027] (1) Preparation of acidified samples: Based on the pH of the acidified early 20th century newspaper in the Ancient Books Collection Room of Liaoning University, which is 4.19, raw Xuan paper was used as the experimental paper. 0.025 mL of 4-14 g / L potassium aluminum sulfate solution was pipetted into a 1 cm × 1 cm area of ​​raw Xuan paper. The raw Xuan paper was saturated with water and the solution spread naturally. It was then dried at room temperature to obtain acidified paper cultural relics samples.

[0028] (2) Preparation of dry heat aging samples: According to the "Accelerated Dry Heat Aging of Paper and Paperboard" (GB / T 464-2008), raw Xuan paper was placed in a vacuum drying oven, the temperature was set to 105℃ and the time was set to 72h to obtain dry heat aging samples of paper cultural relics.

[0029] (3) Preparation of UV-aged samples: Raw Xuan paper was placed in a UV aging chamber with a power of 30W for 24 hours to obtain UV-aged paper cultural relics.

[0030] (4) Experimental grouping

[0031] Experimental setup: Blank group (Ctrl): Blank group (Ctrl) represents untreated acidified sample, dry heat aged sample and UV aged sample respectively.

[0032] Aluminum Sulfate Solution (AGW): Weigh 0.5g of gelatin granules and 0.15g of potassium aluminum sulfate powder into a beaker, add 100ml of distilled water, and stir until dissolved to prepare an Aluminum Sulfate Solution with a gelatin content of 0.5% and a potassium aluminum sulfate content of 0.15%. Use a clean, soft-bristled brush to apply the Aluminum Sulfate Solution evenly to the surface of acidified samples, dry heat-aged samples, and UV-aged samples.

[0033] Hydrogel treatment group (GG): The hydrogel solution obtained in Example 1 (2) is placed in a microwave oven and heated for 3-5 minutes at a temperature of about 85°C until the solution becomes clear and transparent. While it is hot, it is transferred to a mold, cooled and demolded, and then used to cover the surface of acidified samples, dry heat aged samples and UV aged samples.

[0034] CM Dispersion Treatment Group (CM): The CM dispersion obtained in Example 1 (1) was dipped in a clean soft brush and evenly applied to the surface of the acidified sample, the dry heat aged sample and the UV aged sample.

[0035] Hydrogel treatment group with CM dispersion loaded (GG-CM): The hydrogel with CM dispersion loaded obtained in Example 1 (3) was applied to the surface of acidified sample, dry heat aged sample and UV aged sample.

[0036] By comparing with the blank group and the control group (aggregate water group (AGW), hydrogel treatment group (GG), CM dispersion treatment group (CM)), the effect of hydrogel loaded with CM dispersion on paper cultural relics was tested under the conditions of volume ratio of 1:1 and coverage time of 30 min.

[0037] The pH of the paper samples was determined using a pH meter according to GB / T 1545-2008, "Determination of Acidity or Alkalinity of Paper, Paperboard and Pulping Water Extract". The results are as follows: Figure 3As shown, in each group, compared with the Ctrl group, the pH change of the paper samples treated with AGW was not significant. However, the pH of the paper samples treated with GG, CM and GG-CM increased significantly. Each group showed a trend of pH(Ctrl) < pH(AGW) < pH(CM) < pH(GG) < pH(GG-CM), indicating that the hydrogel prepared with CM dispersion at a volume ratio of 1:1 had a better deacidification effect than the other control groups. The pH range after deacidification was between 7.24 and 7.37.

[0038] The tensile strength of the paper sample was determined using a ZQ-21A tensile testing machine. The results are as follows: Figure 4 As shown, among the groups, the tensile strength of paper samples treated with GG increased slightly compared with the Ctrl group. However, the tensile strength of paper samples treated with AGW, CM, and GG-CM increased significantly. All groups showed a trend of tensile strength (Ctrl) < tensile strength (GG) < tensile strength (CM) < tensile strength (AGW) < tensile strength (GG-CM), indicating that the hydrogel prepared with CM dispersion at a volume ratio of 1:1 has a better reinforcement effect than the other control groups. The tensile strength after treatment ranged from 34.5 to 42.9 N.

[0039] Example 3: Application of hydrogels loaded with CM dispersion on paper artifacts after acid reversion.

[0040] The experiment included a blank group (Ctrl), an alum water group (AGW), a hydrogel treatment group (GG), a CM dispersion treatment group (CM), and a hydrogel treatment group loaded with CM dispersion (GG-CM). By comparing with the blank group and the control group, the study examined whether the hydrogel loaded with CM dispersion had a reinforcing effect on deacidified paper artifacts after acid reversion, under conditions of a 1:1 volume ratio and a coverage time of 30 min.

[0041] The tensile strength of the paper sample after acid reversion was determined using a ZQ-21A tensile testing machine. The results are as follows: Figure 5 As shown, in the acidification group and dry heat aging group, the tensile strength of the paper that re-acidified after deacidification treatment with single components AGW, GG and CM increased compared with the blank group. In the UV aging group, the tensile strength of the paper that re-acidified after AGW treatment increased compared with the blank group, while the tensile strength of the paper that re-acidified after GG and CM treatment showed a slight decreasing trend compared with the blank group. However, the tensile strength of the paper that re-acidified after GG-CM treatment showed a significant increasing trend compared with the Ctrl group and other treatment groups. This indicates that the hydrogel loaded with CM dispersion prepared at a volume ratio of 1:1 not only has the effect of deacidifying acidified paper, but also has a reinforcing effect even if re-acidification occurs during storage after deacidification, with a tensile strength range between 33.3-45.3N.

[0042] In summary, the hydrogel loaded with CM dispersion provided by this invention exhibits significantly better deacidification and reinforcement effects compared to traditional deacidification reagents such as alum water (AGW) and individual components. It achieves both deacidification and reinforcement effects, while avoiding the film formation, thickening, hardening, brittleness, and curling phenomena that occur when CM dispersion is used alone on paper. It also improves upon the problem that paper treated with AGW or GG alone only has a single deacidification or reinforcement effect. Even if the paper re-acidifies after deacidification treatment, it still retains the reinforcement effect, avoiding the reduction of mechanical strength, fiber breakage, cracking, and flaking of paper after acidification.

Claims

1. A hydrogel loaded with a CM dispersion, characterized in that, The preparation method includes the following steps: 1) Preparation of CM dispersion: Prepare sodium carboxymethyl cellulose aqueous solution and stir the solution until it is clear and transparent; prepare nano magnesium hydroxide ethanol dispersion; mix equal volumes of sodium carboxymethyl cellulose aqueous solution and nano magnesium hydroxide ethanol dispersion and stir evenly; the concentration of sodium carboxymethyl cellulose aqueous solution is 2-16 g / L; the concentration of nano magnesium hydroxide ethanol dispersion is 8-16 g / L. 2) Preparation of hydrogel solution: Take low-acyl gellan gum, gelatin, and glycerol, add distilled water, swell for 30 min, add calcium acetate to obtain hydrogel solution; the concentration of low-acyl gellan gum is 10-30 g / L, the concentration of gelatin is 5-30 g / L, the concentration of calcium acetate is 0.2-1.2 g / L, and the volume fraction of glycerol is 2.5-15%; 3) Preparation of hydrogel loaded with CM dispersion: Mix the CM dispersion and hydrogel solution, stir evenly, heat in a microwave oven for 3-5 minutes until the solution becomes clear and transparent, transfer it to a mold while hot, and use it after cooling.

2. The hydrogel loaded with CM dispersion according to claim 1, characterized in that, In step 3), the CM dispersion and hydrogel solution are mixed at volume ratios of 2:8, 3:7, 4:6, and 1:

1.

3. The hydrogel loaded with CM dispersion according to claim 1, characterized in that, In step 3), the heating is performed for 3-5 minutes at a temperature of 85°C.

4. The application of the hydrogel loaded with CM dispersion as described in claim 1 in the deacidification and consolidation of paper cultural relics.

5. The application of the hydrogel loaded with CM dispersion as described in claim 1 in the reinforcement of paper cultural relics after acid reversion.

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