Cellulose-based multifunctional composite material capable of reinforcing paper and enhancing hydrophobicity of paper after paper is deacidified

Abstract

The invention discloses a cellulose-based multifunctional composite material capable of reinforcing paper and enhancing hydrophobicity after paper is deacidified, and belongs to the technical field of historical ancient paper cultural relic protection and composite multifunctional materials. The preparation method comprises the following steps: firstly preparing a cellulose-based grafted fluorine-containing copolymer, and then mixing and reacting the cellulose-based grafted fluorine-containing copolymer with a metal hydroxide precursor to obtain the cellulose-based multifunctional composite material. According to the method, the similarity between fluorine-containing cellulose fragments in the multifunctional composite material and the paper composition and structure is utilized, the multifunctional composite material is promoted to permeate into paper fiber gaps and be combined with paper cellulose in the paper deacidification process, and very good reinforcing and hydrophobic effects are achieved, so that after the paper is subjected to deacidification treatment, the paper is not prone to falling off, and the paper quality is improved. According to the present invention, with the application of the multifunctional composite material, the paper has characteristics of excellent mechanical strength, excellent hydrophobicity, alkalescence and high alkali storage capacity, and the multifunctional composite material has good dispersion in the fluorocarbon medium so as to be widely used in the paper deacidification.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of historical ancient book paper cultural relic protection and composite multifunctional material, more specifically, relates to a cellulose-based multifunctional composite material which can reinforce paper and enhance the hydrophobicity of paper after deacidification. BACKGROUND

[0002] The key reason for the aging of paper cultural relics is the acidification and deliquescence of paper. This is because the β-1,4 glycosidic bond connecting the glucose monomers in the cellulose of the paper will gradually undergo hydrolysis under the catalysis of acid, resulting in a decrease in the degree of polymerization of cellulose and a decrease in the mechanical strength of the paper, until the paper is completely weathered into powder, the mechanical strength is completely lost, and the storage and protection value is lost (Relics Protection and Archaeological Science, 2008, 20: 85-94). Therefore, it is particularly important to treat the acid paper cultural relics by deacidification, reinforcement and hydrophobicity.

[0003] At present, great progress has been made in the research and development of paper deacidification materials and deacidification processes at home and abroad, and some deacidification materials and processes have been successfully applied to the preventive protection of paper archives and cultural relics (Acta Chimica Sinica, 2023, 81: 309-318). Among them, the Bookkeeper deacidification process has been applied by many libraries or archives, accounting for about 75% of the paper deacidification market. In recent years, while paying attention to the deacidification of paper, how to enhance the mechanical strength and hydrophobicity of paper has also been paid attention to, that is, to develop multifunctional composite materials. For example, cellulose and its derivatives similar to the components of paper and easy to combine are introduced into multifunctional composite materials to reinforce the strength of paper; alkyl and its derivative hydrophobic materials are introduced to improve the hydrophobicity of paper. Amornkitbamrung et al. (RSC Advances, 2015, 5: 32950-32961) used trimethylsilyl cellulose (TMSC) as a dispersion reinforcing agent to disperse magnesium hydroxide (Mg(OH)2) uniformly in hexamethyldisiloxane (HMDSO), which was used for paper deacidification. After the treatment, the acidic paper became weakly alkaline, and the mechanical strength of the acidic paper was significantly improved while showing excellent hydrophobicity. However, this method is only a simple mechanical mixing of alkaline materials and reinforcing hydrophobic materials, which is difficult to ensure that the deacidification and reinforcing hydrophobic materials are uniformly embedded in the paper fibers. Huang et al. (Journal of Cultural Heritage, 2018, 34: 61-68) dispersed oleic acid-modified magnesium oxide in cyclohexane and soaked acidic paper. After treatment, the pH value of the three acidic papers increased to about 8.0, and the 20 s static water contact angle also increased from 50° to about 120°, showing excellent hydrophobicity. However, the composite material lacks compatibility with paper, and the paper strength is slightly improved. Ma et al. (International Journal of Biological Macromolecules, 2022, 207: 232-241) first uniformly coated cellulose (CNCS) on acidic paper, then sprayed calcium carbonate (CaCO3) and polydimethylsiloxane (PDMS) dispersed in tetrahydrofuran solution on the CNCS-coated acidic paper, and finally deposited methyltrimethoxysilane (MTMS) vapor on the acidic paper. After treatment, the pH value of the acidic paper became 7.70, and due to the stepwise cellulose (CNCS) coating and vapor deposition, the mechanical strength and hydrophobicity of the paper were greatly improved, the tearing degree of the paper increased by 26.51% compared with the untreated paper, and the static water contact angle reached 155.7°. Although this method may disperse the deacidification, reinforcement, and hydrophobic materials uniformly in the paper fiber gap, the multi-step process is not only complicated but also may cause damage to the already fragile paper to some extent.Therefore, it is urgent to develop a multifunctional composite material that can deacidify and has reinforcement, hydrophobicity and other properties.

[0004] Fluorocarbon hydrocarbon is a mainstream solvent for paper deacidification process at present due to its non-flammability, low toxicity and non-damage to writing, etc. (Journal of Cultural Heritage, 2019, 37: 137-147) compared with general organic solvents such as methanol and ethanol. However, the low surface activity of fluorocarbon hydrocarbon makes it difficult for many inorganic and organic materials to be stably dispersed in the fluorocarbon hydrocarbon medium, which brings inconvenience to deacidification operation and seriously affects the deacidification efficiency of paper. In the three patents previously disclosed by the applicant's research group, patent CN108589411A (a composite material of attapulgite and its application) effectively solves the technical problem of paper deacidification and can maintain the alkalinity of paper for a long time; patent CN114753186A (a paper deacidification composite material with high stable suspension and dispersion in fluorocarbon medium, its preparation method and application) effectively solves the problem of high stable suspension and dispersion of deacidification material in fluorocarbon medium; patent CN117107548A (a method for preparing a composite deacidification material for paper deacidification treatment with high alkaline storage and hydrophobicity and its application) effectively solves the problems of high alkaline storage and hydrophobicity of paper after deacidification. The above problems have been solved, and the existing deacidification materials have certain application prospects in paper treatment. However, with the continuous popularization of application, the applicant found that the existing paper deacidification materials have almost no reinforcement performance or insufficient reinforcement performance for paper after deacidification, and the paper deacidification material and the reinforcement and hydrophobic material are not effectively compounded, etc. Therefore, it is necessary to further innovate the existing paper deacidification material to meet the use requirements.

[0005] Application content

[0006] In view of the above problems existing in the prior art, the technical problems to be solved by the present application are to provide a cellulose-based multifunctional composite material that can reinforce paper and enhance its hydrophobicity after deacidification. The material can not only have high dispersibility and high alkaline storage, but also can reinforce paper and enhance its hydrophobicity after deacidification. Another technical problem to be solved by the present application is to provide a preparation method of the above cellulose-based multifunctional composite material that can reinforce paper and enhance its hydrophobicity after deacidification. The method has the characteristics of simple and safe process, environmental protection, etc. The present application also solves the technical problem of providing the application of the above cellulose-based multifunctional composite material in paper deacidification, reinforcement and hydrophobicity.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present application are as follows:

[0008] A method for preparing a cellulose-based multifunctional composite material capable of reinforcing and enhancing the hydrophobicity of paper after deacidification of the paper, comprising the steps of: polymerizing a fluorine-containing monomer and a cellulose macromolecular initiator to obtain a cellulose-based grafted fluorine-containing copolymer; and mixing the cellulose-based grafted fluorine-containing copolymer and a metal hydroxide precursor and then reacting to obtain the cellulose-based multifunctional composite material.

[0009] Preferably, the cellulose macromolecular initiator is prepared by adding cellulose, lithium chloride, N-bromosuccinimide (NBS) and 2-bromoisobutyryl bromide into N,N-dimethylacetamide and reacting, and then cooling to room temperature, filtering, washing and vacuum drying to obtain the cellulose macromolecular initiator.

[0010] Preferably, the cellulose-based grafted fluorine-containing copolymer is prepared by adding the cellulose macromolecular initiator, the fluorine-containing monomer, N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA), CuBr catalyst and N,N-dimethylformamide solvent under nitrogen protection and reacting, and then separating, washing and drying to obtain the cellulose-based grafted fluorine-containing copolymer.

[0011] Preferably, the fluorine-containing monomer is 2-(perfluorooctyl)ethyl methacrylate, and the preparation process and the cellulose-based grafted polymerized 2-(perfluorooctyl)ethyl methacrylate are shown in the reaction formula in the detailed description.

[0012] Preferably, the reaction temperature is 40-60°C, and the reaction time is 2-8h.

[0013] Preferably, the cellulose is any one or more of α-cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose. More preferably, the cellulose is any one or more of α-cellulose, methyl cellulose and ethyl cellulose.

[0014] Preferably, the fluorine-containing monomer is any one or more of perfluoroalkyl ethyl methacrylate and perfluorocycloalkyl ethyl methacrylate. More preferably, the fluorine-containing monomer is any one or more of 2-(perfluorooctyl)ethyl methacrylate, dodecafluoroheptyl methacrylate, perfluorohexyl ethyl acrylate, perfluorobutyl ethyl methacrylate and perfluorocyclohexyl methacrylate.

[0015] Preferably, the mass fraction of the metal hydroxide in the metal hydroxide / cellulose-based grafted fluorine-containing copolymer multifunctional composite material is 30-80%, and the metal hydroxide is any one of magnesium hydroxide and calcium hydroxide.

[0016] As preferred, the metal hydroxide is magnesium hydroxide, and the structure of the magnesium hydroxide / cellulose-based grafted poly 2-(perfluorooctyl)ethyl methacrylate multifunctional composite material prepared is shown in the structure in the detailed description.

[0017] The method for preparing the cellulose-based multifunctional composite material capable of reinforcing and enhancing the hydrophobicity of paper after deacidification of the paper, specifically comprises the following steps:

[0018] 1) preparing a cellulose-based grafted fluorine-containing copolymer;

[0019] 2) preparing an ethanol solution containing calcium ions, magnesium ions and the cellulose-based grafted fluorine-containing copolymer;

[0020] 3) slowly adding a precipitant solution containing sodium hydroxide and hydrazine hydrate to the solution of step 2), and mixing and stirring;

[0021] 4) placing the mixture obtained in step 3) in a reaction kettle for temperature control reaction, and separating, washing and vacuum drying the mixture after reaction to obtain a metal hydroxide / cellulose-based grafted fluorine-containing copolymer multifunctional composite material.

[0022] As preferred, in step 2), the calcium ions are selected from one or more of calcium salts, and the magnesium ions are selected from one or more of magnesium salts. More preferably, the calcium salt and the magnesium salt are selected from any one or more of acetate, sulfate, nitrate, chloride and bicarbonate.

[0023] The method for preparing the cellulose-based multifunctional composite material capable of reinforcing and enhancing the hydrophobicity of paper after deacidification of the paper, and the cellulose-based multifunctional composite material prepared.

[0024] The cellulose-based multifunctional composite material in the application of paper deacidification, reinforcement and hydrophobicity.

[0025] The application, specifically comprising the following steps:

[0026] 1) dispersing the metal hydroxide / cellulose-based grafted fluorine-containing copolymer multifunctional composite material in a fluorocarbon medium and ultrasonic treating for 30 min to obtain a stable suspension, and then using the suspension for paper deacidification; the fluorocarbon medium is selected from any one or more of perfluorooctane, perfluoroheptane, perfluorononane, perfluorobutyltetrahydrofuran, perfluorocycloether, perfluorocyclohexane, perfluoromethylcyclohexane, perfluorotoluene and perfluoro-2,7-dimethyloctane; the concentration of the multifunctional composite material in the paper deacidification suspension is 3-7 g / L;

[0027] 2) immersing the deacidified paper in the paper deacidification suspension for 30 min, and then air drying at room temperature to complete the paper protection treatment.

[0028] In order to solve the technical problem that the paper deacidification material can not reinforce the paper and enhance the hydrophobicity of the paper after deacidification while ensuring high dispersibility, weak alkalinity and high alkali storage, on the basis of the previous work, the cellulose and fluorine-containing copolymer are combined by covalent bond to obtain cellulose-based grafted fluorine-containing copolymer by using graft polymerization technology, so as to ensure that the modified cellulose can be stably suspended and dispersed in fluorocarbon medium, and has good dispersibility. Then, the cellulose-based grafted fluorine-containing copolymer is used as a carrier to prepare a multifunctional composite material by solvothermal method and alkaline deacidification material. In the multifunctional composite material, the specific content of the alkaline component has a deacidification effect on the acidic paper, and can ensure that the paper after deacidification has weak alkalinity and high alkali storage. The similarity between the fluorine-containing cellulose segment in the multifunctional composite material and the composition and structure of the paper promotes the penetration of the multifunctional composite material into the gap between the paper fibers and the combination with the paper cellulose, thereby reinforcing and hydrophobizing. Thus, the multifunctional composite material can ensure high dispersibility, weak alkalinity and high alkali storage while reinforcing the paper and enhancing the hydrophobicity of the paper after deacidification.

[0029] Compared with the prior art, the beneficial effects of the present application are:

[0030] (1) The cellulose-based multifunctional composite material prepared in the present application is first combined with fluorine-containing copolymer by covalent bond, and then metal hydroxide is loaded on the cellulose-based grafted fluorine-containing copolymer by hydrogen bond to prepare the multifunctional composite material. This multifunctional composite material can ensure that the deacidification, reinforcement and hydrophobic material is uniformly distributed and embedded in the gap between the paper fibers.

[0031] (2) The cellulose in the cellulose-based multifunctional composite material prepared in the present application has many hydroxyl groups and a large number of hydrogen bond sites, and has good compatibility with paper and excellent mechanical properties, so that the multifunctional composite material has excellent paper reinforcement performance. The fluorine-containing polymer in the cellulose-based multifunctional composite material not only stably suspends and disperses in fluorocarbon medium, but also has hydrophobicity, so that the paper after deacidification shows strong hydrophobicity, which is beneficial to its long-term preservation. In addition, the inorganic metal hydroxide grows on the cellulose-based grafted fluorine-containing copolymer, thereby avoiding direct contact with the paper, so that the paper after deacidification has weak alkalinity under high alkali storage.

[0032] (3) The cellulose-based multifunctional composite material prepared in the present application can be stably suspended and dispersed in fluorocarbon medium by simple ultrasonic treatment. The acidified paper is soaked in the deacidifier for deacidification, which is simple and easy.

[0033] (4) The results of the examples of the present application prove that the cellulose-based multifunctional composite material, after deacidification treatment of paper, increases the surface pH value of the paper from the original 4.73 to 7.43, and the alkali reserve is 310.88 mmol / kg. Compared with the untreated paper, the folding endurance, tensile strength, tear resistance and water contact angle of the treated paper are increased by 94.6%, 29.9%, 20.4% and 134.7% respectively, solving the problem of brittleness of acidified paper, and having good application value in the deacidification protection of paper cultural relics. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a flow chart of the preparation of the cellulose-based multifunctional composite material of the present application;

[0035] Figure 2 is an infrared spectrum of cellulose (a), cellulose macromolecular initiator (b), cellulose-based multifunctional composite material Mg(OH)2 / Cellulose-g-PFOEMA (c) prepared in Example 1, Mg(OH)2(d) and PFOEMA monomer (e);

[0036] Figure 3 is a scanning electron microscope image of the cellulose-based multifunctional composite material Mg(OH)2 / Cellulose-g-PFOEMA sample prepared in Example 1;

[0037] Figure 4 is a suspended optical photograph of the paper deacidification agent prepared in Application Example 6; in the figure, A is a suspended optical photograph of the paper deacidification agent prepared in Example 1, B is a suspended optical photograph of the paper deacidification agent prepared in Comparative Example 1, and C is a suspended optical photograph of the paper deacidification agent prepared in Comparative Example 2;

[0038] Figure 5 is a mechanical strength diagram of the paper before and after deacidification in Application Example 6 and after aging; in the figure, A is folding endurance, B is tensile strength, and C is tear resistance;

[0039] Figure 6 is a scanning electron microscope image of the paper before and after deacidification in Application Example 6; in the figure, A is the paper without deacidification treatment, and B is the paper after deacidification treatment;

[0040] Figure 7 is a stable water contact angle diagram of the paper before and after deacidification and after aging in Application Example 6. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described below in combination with specific examples. Unless otherwise specified, the technical means used in the following examples are all conventional means known to those skilled in the art. If no specific conditions are indicated in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If no manufacturer of the reagent or instrument is indicated, it is a conventional product that can be obtained by market purchase.

[0042] The present application provides a preparation method of a cellulose grafted fluorine-containing polymer carrier using 2-(perfluorooctyl)ethyl methacrylate (PFOEMA) as a fluorine-containing monomer for a multifunctional cellulose-based composite material capable of reinforcing paper and enhancing the hydrophobicity of the paper after deacidification, and the reaction formula is as follows:

[0043]

[0044] The process flow is shown in Figure 1 and specifically includes the following steps:

[0045] 1) Preparation of cellulose macromolecular initiator: cellulose, lithium chloride, N-bromosuccinimide, 2-bromoisobutyryl bromide and N,N-dimethylacetamide solvent are reacted to obtain a cellulose macromolecular initiator;

[0046] 2) Preparation of cellulose-based grafted fluorine-containing copolymer: the cellulose macromolecular initiator prepared in step 1), fluorine-containing monomer, N,N,N',N",N"-pentamethyldiethylene triamine, CuBr catalyst and N,N-dimethylformamide solvent are reacted under nitrogen protection, and after the reaction is completed, the cellulose-based grafted fluorine-containing copolymer is obtained after separation, washing and drying;

[0047] 3) Preparation of cellulose-based multifunctional composite material: a magnesium salt or a calcium salt is dissolved in anhydrous ethanol, the cellulose-based grafted fluorine-containing copolymer is added, and then a precipitate containing sodium hydroxide and hydrazine hydrate is slowly titrated to obtain a mixed solution, and the cellulose-based multifunctional composite material is prepared after temperature control reaction. The typical structure formula of the cellulose-based multifunctional composite material is as follows:

[0048]

[0049] The following specific examples are all carried out according to the above process, wherein the average length of the selected α-cellulose is 25 μm.

[0050] Example 1

[0051] A preparation method of a cellulose-based multifunctional composite material capable of reinforcing paper and enhancing the hydrophobicity of the paper after deacidification, comprising the following steps:

[0052] (1) Preparation of cellulose macromolecular initiator:

[0053] Into 90 mL of N,N-dimethylacetamide was added 3.24 g of a- cellulose, and the reaction was stirred at 120°C for 2 h. After the reaction was completed, the temperature was lowered to 100°C, 7.2 g of lithium chloride was added, and the reaction was carried out at 100°C for 5 h. After the reaction was completed, the temperature was lowered to 50°C, 0.72 g of N-bromosuccinimide was added, and after the reaction was carried out for 10 min, 23.0 g of 2-bromoisobutyryl bromide was added. Finally, the obtained reaction solution was reacted at 50°C for 48 h, and after it was cooled to room temperature, it was filtered, washed to remove impurities, and vacuum-dried at 50°C to obtain a cellulose macromolecular initiator, which was designated as Cellulose-Br.

[0054] (2) Preparation of a cellulose-based grafted fluorine-containing copolymer (cellulose grafted poly(2-(perfluorooctyl)ethyl methacrylate):

[0055] Into 85 mL of N,N-dimethylformamide was added 0.5 g of Cellulose-Br prepared in step (1), and 0.1733 g of N,N,N',N",N"-pentamethyldiethylenetriamine and 2.0 g of 2-(perfluorooctyl)ethyl methacrylate were further added. The obtained reaction solution was injected into a three-necked flask which was previously vacuumed and filled with nitrogen (cycled three times) using a syringe, and the reaction was carried out at 50°C for 30 min. Into 15 mL of N,N-dimethylformamide was dissolved 0.0718 g of cuprous bromide to prepare a catalyst. The prepared catalyst was injected into the three-necked flask using a syringe, and the reaction was carried out at 50°C for 4 h. After it was cooled to room temperature, it was filtered, washed to remove impurities, and vacuum-dried at 50°C to prepare cellulose grafted poly(2-(perfluorooctyl)ethyl methacrylate), which was designated as Cellulose-g-PF OEMA.

[0056] (3) Preparation of a cellulose-based multifunctional composite material:

[0057] 0.429 g of magnesium acetate tetrahydrate was dissolved in 20 mL of anhydrous ethanol under ultrasonic treatment (70 W power, 40 kHz frequency), and 0.464 g of Cellulose-g-PFOEMA carrier prepared in step (2) was added. The mixture was stirred ultrasonically (70 W power, 40 kHz frequency) at room temperature and then set aside. 0.16 g of sodium hydroxide was dissolved in 20 mL of aqueous solution, and 4.0 mL of 80% hydrazine hydrate was added to prepare a precipitate. The precipitate was slowly added dropwise to the above-mentioned prepared solution and stirred at room temperature for 30 min. The mixed solution was then transferred to a 100 mL reactor lined with polytetrafluoroethylene and reacted at 150 °C for 12 h. After cooling to room temperature, the mixture was centrifuged and washed to remove impurities, thus obtaining a cellulose-based multifunctional composite material, denoted as Mg(OH)2 / Cellulose-g-PFOEMA, in which the mass fraction of magnesium hydroxide in the cellulose-based multifunctional composite material was 55-60%.

[0058] Depend on Figure 2 It can be seen that 3334cm in the figure -1 1056cm -1 and 1029cm -1 The absorption peaks are the vibrational absorption peaks of -OH on cellulose (a) and CO, respectively; 3700 cm⁻¹ -1 The absorption peak is the vibrational absorption peak of the -OH group of magnesium hydroxide (d); 1241 cm⁻¹ -1 1205cm -1 1149cm -1 1725cm -1 and 1639cm -1 The absorption peaks at 664 cm⁻¹ are characteristic absorption peaks of the CF group, -C=O group, and C=C group of the 2-(perfluorooctyl)ethyl methacrylate monomer (e), respectively. -1 The C-Br group of the cellulose macromolecular initiator (b) indicates that the cellulose has been brominated; the Mg(OH)2 / Cellulose-g-PFOEM A composite deacidifying material (c) at 3334 cm⁻¹ -1 The weakening peak intensity at 1735 cm⁻¹ indicates that the cellulose -OH groups have been partially substituted; -1 A sharp peak appears at 1241 cm⁻¹, which is the absorption peak of the -C=O vibration of the ester bond in the Mg(OH)₂ / Cellulose-g-PFOEMA composite deacidification material; while at 1241 cm⁻¹... -1 1205cm -1 1149cm -1 The appearance of the characteristic peak of the CF group indicates that the grafting of monomer 2-(perfluorooctyl)ethyl methacrylate was successful; while the peak at 1639 cm⁻¹... -1The disappearance of the characteristic absorption peak indicates that the 2-(perfluorooctyl) ethyl methacrylate monomer is polymerized. In addition, compared with the original Mg(OH)2, the 3700 cm -1 The decrease of the hydroxyl peak indicates that the Mg(OH)2 and Cellulose-g-PFOEMA have hydrogen bonding.

[0059] From the above results, it can be seen that the synthesized regular hexagonal magnesium hydroxide nanosheets are uniformly dispersed on the Cellulose-g-PFOEMA carrier. Figure 3

[0060] Example 2

[0061] The preparation method of the cellulose-based grafted fluorine-containing copolymer is the same as that in step 2) of Example 1, except that the selected fluorine-containing monomer is replaced by dodecafluoroheptyl methacrylate (DFMA), perfluorohexyl ethyl acrylate (PFHEA), perfluorobutyl ethyl methacrylate (PFBEMA), and perfluorocyclohexyl methacrylate (PFCHMA), respectively. The prepared cellulose-based grafted fluorine-containing copolymers are marked as Cellulose-g-DFMA, Cellulose-g-PFHEA, Cellulose-g-PFBEMA, and Cellulose-g-PFCHMA, respectively.

[0062] Example 3

[0063] The preparation of the cellulose-based multifunctional composite material is the same as that in step 3) of Example 1, except that different amounts of the Cellulose-g-PFOEMA carrier prepared in step 2) are added, as follows:

[0064] 1) 0.116 g of Cellulose-g-PFOEMA carrier is added, and the mass fraction of magnesium hydroxide in the prepared composite deacidification material Mg(OH)2 / Cellulose-g-PFOEMA is 85-90%.

[0065] 2) 0.232 g of Cellulose-g-PFOEMA carrier is added, and the mass fraction of magnesium hydroxide in the prepared composite deacidification material Mg(OH)2 / Cellulose-g-PFOEMA is 75-80%.

[0066] 3) 0.348 g of Cellulose-g-PFOEMA carrier is added, and the mass fraction of magnesium hydroxide in the prepared composite deacidification material Mg(OH)2 / Cellulose-g-PFOEMA is 65-70%.

[0067] ​4) adding 0.58 g of Cellulose-g-PFOEMA carrier, the mass fraction of magnesium hydroxide in the composite deacidification material Mg(OH)2 / Cellulose-g-PFOEMA prepared is 45-50%.

[0068] Example 4

[0069] The preparation method of the cellulose-based multifunctional composite material is the same as that in Example 1, except that in step 3), 0.464 g of Cellulose-g-DFMA carrier, Cellulose-g-PFHEA carrier, Cellulose-g-PFBEMA carrier and Cellulose-g-PFCHMA carrier prepared in Example 2 are respectively added, and the mass fraction of magnesium hydroxide in the composite deacidification material (Mg(OH)2 / Cellulose-g-DFMA, Mg(OH)2 / Cellulose-g-PFHEA, Mg(OH)2 / Cellulose-g-PFBEMA and Mg(OH)2 / Cellulose-g-PFCHMA respectively) prepared is 55-60%.

[0070] Example 5

[0071] The preparation method of the cellulose-based multifunctional composite material is the same as that in Example 1, except that in step 3), 0.316 g of calcium acetate is used to replace 0.429 g of magnesium acetate tetrahydrate, and the target product is obtained, as follows:

[0072] 1) adding 0.116 g of Cellulose-g-PFOEMA carrier, the mass fraction of calcium hydroxide in the composite deacidification material Ca(OH)2 / Cellulose-g-PFOEMA prepared is 85-90%.

[0073] 2) adding 0.232 g of Cellulose-g-PFOEMA carrier, the mass fraction of calcium hydroxide in the composite deacidification material Ca(OH)2 / Cellulose-g-PFOEMA prepared is 75-80%.

[0074] 3) adding 0.348 g of Cellulose-g-PFOEMA carrier, the mass fraction of calcium hydroxide in the composite deacidification material Ca(OH)2 / Cellulose-g-PFOEMA prepared is 65-70%.

[0075] 4) adding 0.464 g of Cellulose-g-PFOEMA carrier, the mass fraction of calcium hydroxide in the composite deacidification material Ca(OH)2 / Cellulose-g-PFOEMA prepared is 55-60%.

[0076] 5) Add 0.58g Cellulose-g-PFOEMA carrier, the mass fraction of calcium hydroxide in the composite deacidification material Ca(OH)2 / Cellulose-g-PFOEMA is 45-50%.

[0077] Comparative Example 1

[0078] 0.429g magnesium acetate tetrahydrate was dissolved in 20mL anhydrous ethanol under the action of ultrasonic wave (power 70w, frequency 40Khz) at room temperature, and then stirred under ultrasonic wave (power 70w, frequency 40Khz) at room temperature; 0.16g sodium hydroxide was dissolved in 20mL aqueous solution, and 4.0mL 80% hydrazine hydrate was added to prepare a precipitate solution; the precipitate solution was slowly dropped into the above prepared solution and stirred at room temperature for 30min, and then the mixed solution was moved into a 100mL reaction kettle lined with polytetrafluoroethylene and reacted at 150℃ for 12h, and then centrifuged, washed and separated to remove impurities to obtain pure Mg(OH)2.

[0079] Comparative Example 2

[0080] In the preparation of cellulose grafting poly (methyl methacrylate) octadecyl ester, the monomer selected was poly (methyl methacrylate) octadecyl ester (SMA), and the rest of the preparation method and parameters were the same as those in Example 1, step 2), and marked as Cellulose-g-SMA; in the preparation of metal hydroxide / cellulose-based grafted non-fluorine-containing copolymer multifunctional composite material, 0.464g of prepared Cellulose-g-SMA carrier was added, and the rest of the preparation method and parameters were the same as those in Example 1, step 3), and the composite deacidification material Mg(OH)2 / Cellulose-g-SMA was prepared.

[0081] Application Example 6

[0082] 1. Comparison of dispersion performance

[0083] 1.4g of the deacidification material was uniformly dispersed in 200mL of perfluorooctane mixed solution, and ultrasonic dispersion (power 70w, frequency 40Khz) was carried out for 30min, and the dispersion performance of the product was observed after standing, and the results are shown in Table 1. Figure 4

[0084] Figure 4 A is Mg(OH)2 / Cellulose-g-PFOEMA prepared in Example 1, and the composite deacidification material can be stably suspended and dispersed in perfluorooctane mixed solvent, and the stable suspension and dispersion time is not less than 120min.

[0085] Figure 4 ​B is Mg(OH)2material prepared in Comparative Example 1, after standing for 30 min, Mg(OH)2has obvious settlement.

[0086] Figure 4 C is composite deacidification material Mg(OH)2 / Cellulose-g-SMA prepared in Comparative Example 2, after standing for 10 min, solid particles have obvious settlement, indicating that the non-fluorine-containing carrier has poor suspension.

[0087] 2. Deacidification performance comparison

[0088] The average pH value of the acid paper is 4.73, and the acid paper is soaked in the Mg(OH)2 / Cellulose-g-PFOEMA perfluoroalkane mixed solution for deacidification, during which the paper is gently shaken with tweezers and turned every 5 min, and the treated paper is placed at room temperature for 24 h. The treated paper is detected by the national standard GB / T1545.2-2003 method, and the surface pH value of the paper treated by the multifunctional composite material Mg(OH)2 / Cellulose-g-PFOEMA is increased from 4.73 to 7.43, and the alkali storage is 310.88 mmol / kg (see Table 1), showing weak alkalinity and high alkali storage.

[0089] The above deacidified paper is placed in an oven at 105°C for dry heat aging for 72 h. The treated paper is detected by the national standard GB / T1545.2-2003 method, and the surface average pH value of the paper treated by the multifunctional composite material is 7.35, and the alkali storage is 289.44 mmol / kg, while the surface average pH value of the untreated paper after aging is 4.35, indicating that the paper treated by the multifunctional composite material Mg(OH)2 / Cellulose-g-PFOEMA has anti-aging performance.

[0090] The paper mechanical strength (folding endurance, tensile strength and tear resistance), microstructure and hydrophobicity (water contact angle) of the above deacidified paper and dry heat aged paper before and after deacidification are measured, and the results are shown in Figures 5-7 and Table 1.

[0091] Table 1 Performance results of paper samples

[0092]

[0093] From Figure 5As shown in Table 1, the mechanical strength of paper treated with the multifunctional composite material Mg(OH)2 / Cellulose-g-PFOEMA is significantly improved. Compared with untreated paper, the folding endurance, tensile strength, and tear strength of the treated paper are increased by 94.6%, 29.9%, and 20.4%, respectively. Even after dry heat aging treatment, it still exhibits excellent mechanical strength compared with untreated paper, with folding endurance, tensile strength, and tear strength increased by 67.4%, 23.4%, and 14.1%, respectively. This indicates that the paper treated with the multifunctional composite material Mg(OH)2 / Cellulose-g-PFOEMA has good anti-aging properties and excellent mechanical strength.

[0094] Depend on Figure 6 It can be seen that, compared to untreated paper ( Figure 6 A) Multifunctional composite materials can be uniformly embedded inside paper fibers. Figure 6 B), thereby improving the mechanical strength of the paper.

[0095] Depend on Figure 7 It can be seen that the water contact angle of the untreated acidic paper was 52.5° after 20 minutes of water contact angle test, while the water contact angles of the paper treated with multifunctional composite material before and after aging were 123.2° and 127.5°, respectively, indicating that the paper treated with multifunctional composite material exhibits excellent hydrophobicity.

[0096] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for preparing a cellulose-based multifunctional composite material capable of reinforcing paper and enhancing the hydrophobicity of the paper after deacidification of the paper, characterized by, The cellulose-based grafting fluorine-containing copolymer is prepared by polymerization of fluorine-containing monomers and cellulose macromolecular initiators, and then mixed with metal hydroxide precursors to obtain the cellulose-based multifunctional composite material.

2. The method for preparing a cellulose-based multifunctional composite material that can strengthen paper and enhance its hydrophobicity after deacidification, as described in claim 1, is characterized in that... Specifically comprising the following steps: 1) reacting cellulose, lithium chloride, N-bromosuccinimide, 2-bromoisobutyryl bromide and N,N-dimethylacetamide solvent to obtain cellulose macromolecular initiator; 2) reacting the cellulose macromolecular initiator prepared in step 1) with fluorine-containing monomers, N,N,N',N",N"-pentamethyldiethylenetriamine, CuBr catalyst and N,N-dimethylformamide solvent under nitrogen protection, and then separating, washing and drying to obtain cellulose-based grafting fluorine-containing copolymer; 3) dissolving magnesium salt or calcium salt in anhydrous ethanol, adding the cellulose-based grafting fluorine-containing copolymer, slowly adding a precipitant solution containing sodium hydroxide and hydrazine hydrate, and then obtaining the cellulose-based multifunctional composite material after temperature control reaction.

3. The method of claim 2, wherein the cellulose-based multifunctional composite material is prepared by the steps of: (a) preparing a paper sheet; (b) impregnating the paper sheet with a solution of a cellulose-based multifunctional composite material; (c) drying the impregnated paper sheet; (d) deacidifying the dried paper sheet; and (e) reinforcing the deacidified paper sheet and enhancing the hydrophobicity of the deacidified paper sheet. In step 1), the mass ratio of cellulose, lithium chloride, N-bromosuccinimide, 2-bromoisobutyryl bromide and N,N-dimethylacetamide solvent is 3-3.5:7-7.5:0.5-1:23:80-90.

4. The method for preparing a cellulose-based multifunctional composite material that can strengthen paper and enhance its hydrophobicity after deacidification, as described in claim 2, is characterized in that... In step 1), the cellulose is selected from any one or more of α-cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose.

5. The method for preparing a cellulose-based multifunctional composite material that can strengthen paper and enhance its hydrophobicity after deacidification, as described in claim 2, is characterized in that... In step 2), the mass ratio of cellulose macromolecular initiator, fluorine-containing monomers, N,N,N',N",N"-pentamethyldiethylenetriamine, CuBr catalyst and N,N-dimethylformamide solvent is 0.5:2:0.15-0.2:0.05-0.1:95-100.

6. The method of claim 2, wherein the cellulose-based multifunctional composite material is prepared by the steps of: (a) preparing a paper sheet; (b) impregnating the paper sheet with a solution of a cellulose-based multifunctional composite material; (c) drying the impregnated paper sheet; (d) washing the dried paper sheet; (e) drying the washed paper sheet; and (f) calcining the dried paper sheet. In step 2), the reaction temperature is 40-60°C, and the reaction time is 2-8h.

7. The method for preparing a cellulose-based multifunctional composite material that can strengthen paper and enhance its hydrophobicity after deacidification, as described in claim 2, is characterized in that... In step 2), the fluorine-containing monomer is selected from any one of 2-(perfluorooctyl)ethyl methacrylate, dodecafluoroheptyl methacrylate, perfluorohexyl ethyl acrylate, perfluorobutyl ethyl methacrylate and perfluorocyclohexyl methacrylate.

8. The method of claim 2, wherein the cellulose-based multifunctional composite material is prepared by the following steps: (1) preparing a paper sheet; (2) adding a deacidification agent to the paper sheet to remove acid from the paper sheet; (3) adding a reinforcing agent to the paper sheet to reinforce the paper sheet; and (4) adding a hydrophobic agent to the paper sheet to enhance the hydrophobicity of the paper sheet. In step 3), the mass fraction of metal hydroxide in the metal hydroxide / cellulose-based grafting fluorine-containing copolymer multifunctional composite material is 30-80%, and the metal hydroxide is selected from any one of magnesium hydroxide and calcium hydroxide.

9. The preparation method of the cellulose-based multifunctional composite material for deacidifying, reinforcing and hydrophobizing paper, according to any one of claims 1-8.

10. The application of the cellulose-based multifunctional composite material in deacidification, reinforcement and hydrophobicity of paper.

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