Paper deacidification liquid and preparation method thereof

Abstract

The invention relates to a paper deacidification liquid and a preparation method thereof, the paper deacidification liquid comprises a fluorocarbon deacidification liquid and an alkaline deacidification substance, the fluorocarbon deacidification liquid comprises, by volume, 1-10% of perfluoropolyether, 10-30% of a perfluoroether solvent and 60-89% of perfluorohexanone, and the ratio of the mass of the alkaline deacidification substance to the volume of the fluorocarbon solvent is 0.1-10 g / L. According to the fluorine-containing paper deacidification liquid, a synergistic effect is generated by virtue of opposite electrostatic potentials of perfluoroether and perfluoroketone, a steric hindrance effect is formed by virtue of perfluoropolyether with a long molecular chain, and the fluorine-containing paper deacidification liquid with high-stability suspension dispersion is obtained without depending on perfluorocarboxylate and perfluorosilane surfactants. The pH value and the alkali storage capacity of the treated paper are remarkably improved, meanwhile, the paper cannot be wrinkled and adhered, and the color difference, the tensile strength and the handwriting change of the paper are not obvious. The adopted fluorine-containing solvent is high in inertia, rapid in volatilization, low in price and suitable for large-scale paper deacidification treatment.

Description

Technical Field

[0001] This invention belongs to the field of paper deacidification technology, specifically relating to a paper deacidification solution and its preparation method. Background Technology

[0002] Since its invention, paper has become the primary medium for recording human history and culture, possessing immense research value. Especially after the 1830s, the widespread use of mechanical printing presses and the optimization of papermaking processes made paper the cheapest tool for recording text. However, in modern times, the vast majority of paper artifacts have suffered varying degrees of damage, resulting in incalculable losses.

[0003] Paper is primarily composed of cellulose, a polymer composed of glucose monomers linked together by β-1,4 glycosidic bonds. These cellulose molecules are further interconnected by hydrogen bonds, forming the paper. However, β-1,4 glycosidic bonds are highly susceptible to hydrolysis in acidic environments. Hydrolysis of these bonds generates acidic groups such as carboxylic acids, accelerating cellulose breakdown and causing paper performance degradation, aging, and damage. In the last century, to ensure smoothness, whiteness, and suitable strength, papermaking processes often incorporated additives containing aluminum sulfate and chlorides. Over time, these additives release acidic substances like hydrochloric acid into the air, resulting in severe acidification and damage to many modern paper artifacts.

[0004] Since the last century, several deacidification systems have been developed both domestically and internationally for these acidified paper artifacts. Based on the different dispersion media, they can be divided into liquid-phase deacidification and gas-phase deacidification. Liquid-phase deacidification is the earliest developed and most widely used deacidification technology, relying on soluble alkaline solutes (such as sodium hydroxide, calcium hydroxide) or insoluble alkaline particles (such as magnesium or calcium carbonates) to neutralize the acidic substances in the paper. Currently, the most promising liquid-phase deacidification system uses fluorinated organic solvents as the dispersion medium and alkaline nanoparticles as the alkaline source to prepare the deacidifying solution. Fluorinated organic solvents are organic solvents in which some or all of the hydrogen elements in the molecule are replaced by fluorine elements. Due to the shielding effect of fluorine atoms, the intermolecular forces of this solvent are extremely low, thus exhibiting good inertness and volatility. When used as a paper deacidifying solution, it has advantages such as minimal impact on ink marks, no paper wrinkling, fast drying, and convenient processing.

[0005] Kopper Corporation, in collaboration with the University of California, developed a paper deacidifying agent that was the first to use a fluorinated organic solvent as the deacidifying liquid, and published a related patent, "DEACIDIFICATION OF LIBRARY MATERIALS." The product is now widely used. However, due to the low intermolecular forces of fluorinated organic solvents, alkaline nanoparticles dispersed within them are prone to agglomeration, necessitating the addition of large amounts of perfluorinated surfactants to prevent particle aggregation. Kopper's "Bookkeeper" deacidifying liquid used perfluorocarboxylic acid esters as surfactants, and CN117107548A similarly used fluoroalkyl methacrylates as surfactants to aid in the dispersion of alkaline nanoparticles. Because these substances are not easily volatile and possess the characteristics of ester compounds, they may accumulate in organisms, and the large amount of surfactant also increases the cost of the deacidifying liquid.

[0006] In summary, the superior performance of deacidifying solutions using fluorinated organic solvents makes them a popular research subject in the field of paper artifact preservation; however, the high cost of fluorinated surfactants prevents their large-scale application. Therefore, finding new ways to replace surfactants and improve the dispersibility of alkaline nanoparticles is an urgent problem for researchers in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a highly stable and dispersible fluorinated paper deacidifying solution to overcome the shortcomings of existing technologies. Another objective is to provide a method for preparing the aforementioned paper deacidifying solution. By performing molecular modeling and surface electrostatic potential analysis on various perfluorinated solvents, perfluorinated ethers and perfluorinated ketones with opposite charges were screened. These solvents are adsorbed by electrostatic interactions to form long chains. The steric hindrance of these long-chain molecules enhances the dispersion stability of the deacidified product. The addition of perfluorinated polyethers, which are long-chain molecules, further strengthens this effect. This invention relies on electrostatic potential to form long-chain molecules, circumventing domestic and international restrictions on long-chain monomolecule perfluorinated compounds, such as EU Regulation (EU) 2021 / 1297. The solvents used in this invention are non-biological and environmentally harmful, and no harmful substances remain on the treated paper.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a paper deacidification solution, characterized in that it is composed of a fluorocarbon deacidification solution and an alkaline deacidifying agent; wherein the fluorocarbon deacidification solution is composed of a perfluoropolyether solvent, a perfluoroether solvent, and a perfluoroketone solvent, wherein the perfluoropolyether solvent accounts for 1-10% of the volume percentage of the fluorocarbon deacidification solution, the perfluoroether solvent accounts for 10-30% of the volume percentage of the fluorocarbon deacidification solution, and the perfluoroketone solvent accounts for 60-89% of the volume percentage of the fluorocarbon deacidification solution; the alkaline deacidifying agent is an alkaline earth metal compound nanoparticle, and the mass ratio of the alkaline deacidifying agent to the volume of the fluorocarbon deacidification solution is 0.1-10 g / L.

[0009] Preferably, the perfluoropolyether solvent is a perfluoropolyether with an average molecular weight of 800 to 6000 Da.

[0010] Preferably, the perfluoroether solvent is one or more of perfluorobutyl methyl ether, methyl nonafluorobutyl ether, or hexafluoropropyl methyl ether.

[0011] Preferably, the perfluoroketone solvent is one or both of perfluorohexanone or perfluoropentanone.

[0012] Preferably, the alkaline earth metal compound is one or more of alkaline earth metal hydroxides, alkaline earth metal carbonates, or alkaline earth metal bicarbonates.

[0013] Preferably, the alkaline earth metal in the alkaline earth metal compound is one or more of magnesium, calcium, or zinc.

[0014] Preferably, the alkaline earth metal compound nanoparticles have a particle size of 10 nm to 1 μm.

[0015] The present invention also provides a method for preparing the above-mentioned paper deacidification solution, the specific steps of which are as follows: first, a perfluoroether solvent is mixed into a perfluoroketone solvent and mechanically stirred evenly at a speed of 200-800 r / min for 5-20 min; then, a perfluoropolyether is added and mechanically stirred evenly at a speed of 200-800 r / min for 5-20 min; finally, an alkaline deacidifying agent is added and dispersed evenly using an ultrasonic disperser at an ultrasonic power of 200-1000 W for 10-30 min.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] The deacidification solution using fluorinated organic solvents described in this invention, through electrostatic potential analysis of some fluorinated organic solvents, screens out perfluoroethers and perfluoroketones with opposite surface charges. The synergistic effect of the mixed fluorinated solvents gives it a good steric hindrance effect, which is enhanced by the addition of perfluoropolyethers with long molecular chains. The prepared fluorinated organic solvent has a moderate cost and complies with domestic and international regulations on perfluorinated compounds, such as EU Regulation (EU) 2021 / 1297. Furthermore, it achieves a deacidification suspension with excellent dispersion stability without relying on perfluorinated surfactants. After paper treatment, the paper does not deform and dries rapidly without introducing other functional groups, making it suitable for large-scale, low-cost paper deacidification. Attached Figure Description

[0018] Figure 1 A comparison image of optical photographs of the paper deacidification solution prepared in Example 1 and commercially available deacidification solutions;

[0019] Figure 2 The diagram shows the electrostatic potential of the perfluorobutyl methyl ether molecule and the perfluorohexanone molecule used in Example 1; where (a) is the electrostatic potential diagram of the perfluorobutyl methyl ether molecule and (b) is the electrostatic potential diagram of the perfluorohexanone molecule. Detailed Implementation

[0020] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0021] Example 1

[0022] The average molecular weight of the perfluoropolyether in this embodiment is 800 Da;

[0023] In this embodiment, the nano-magnesium oxide particles have a diameter of 10 nm;

[0024] First, mix 10 ml of perfluorobutyl methyl ether solvent into 89 ml of perfluorohexanone solvent, stir mechanically until homogeneous at 200 r / min for 5 min, add 1 ml of perfluoropolyether, stir mechanically until homogeneous at 200 r / min for 5 min, add 0.01 g of nano magnesium oxide, and disperse evenly using an ultrasonic disperser at 200 W for 30 min.

[0025] Place the above paper deacidification solution in a 250ml beaker, immerse the paper in the deacidification solution for 15 minutes, remove the treated paper, and let the paper air dry naturally at room temperature.

[0026] The paper used in this embodiment is a page from an ancient book, weighing 2g, with a basis weight of 30g / m³.2 ;

[0027] The schematic diagram of the dispersion effect and electrostatic potential of the paper deacidification solution prepared in this embodiment is shown below. Figure 1 and Figure 2 As shown, compared with commercially available fluorocarbon deacidifying solutions, the paper deacidifying solution of the present invention has better suspension properties. The electrostatic potential diagram shows that perfluorohexanone and perfluorobutyl methyl ether have opposite electrostatic potentials, which helps the molecules of both adsorb.

[0028] Example 2

[0029] The average molecular weight of the perfluoropolyether in this embodiment is 1200 Da;

[0030] In this embodiment, the particle size of the nano-calcium carbonate is 30 nm;

[0031] First, mix 15 ml of hexafluoropropyl methyl ether solvent into 80 ml of perfluorohexanone solvent, and mechanically stir until homogeneous at 300 r / min for 10 min. Then, add 5 ml of perfluoropolyether and mechanically stir until homogeneous at 300 r / min for 10 min. Finally, add 0.1 g of nano calcium carbonate and disperse it evenly using an ultrasonic disperser at 400 W for 25 min.

[0032] Place the above paper deacidification solution in a spray bottle and spray it evenly on both sides of the paper. Let the paper dry at room temperature.

[0033] The paper used in this embodiment is a page from an antique book from the Qing Dynasty, weighing 3g, with a basis weight of 25g / m³. 2 ;

[0034] Example 3

[0035] The average molecular weight of the perfluoropolyether in this embodiment is 3000 Da;

[0036] In this embodiment, the particle size of the nano-magnesium hydroxide is 100 nm;

[0037] First, mix 20 ml of methyl nonafluorobutyl ether solvent into 75 ml of perfluorohexanone solvent, stir mechanically until homogeneous at 500 r / min for 12 min, add 5 ml of perfluoropolyether, stir mechanically until homogeneous at 500 r / min for 12 min, add 0.4 nm magnesium hydroxide, and disperse evenly using an ultrasonic disperser at 600 W for 20 min.

[0038] Place the above paper deacidification solution in a 250ml beaker, immerse the paper in the deacidification solution for 20 minutes, remove the treated paper and air dry it naturally in a fume hood;

[0039] The paper used in this embodiment is a page from an ancient book, weighing 3g, with a basis weight of 30g / m³. 2 ;

[0040] Example 4

[0041] The average molecular weight of the perfluoropolyether in this embodiment is 4200 Da;

[0042] In this embodiment, the particle size of the nano-magnesium hydroxide is 500 nm;

[0043] First, mix 24 ml of hexafluoropropyl methyl ether solvent into 68 ml of perfluoropentanone solvent, and mechanically stir until homogeneous at 600 r / min for 16 min. Then, add 8 ml of perfluoropolyether and mechanically stir until homogeneous at 600 r / min for 16 min. Finally, add 0.8 g of nano-calcium bicarbonate and disperse it evenly using an ultrasonic disperser at 800 W for 15 min.

[0044] Place the above paper deacidification solution in a 250ml beaker, immerse the paper in the deacidification solution for 20 minutes, remove the treated paper and air dry it naturally in a fume hood;

[0045] The paper used in this embodiment is a page from an ancient book, weighing 2g, with a basis weight of 30g / m³. 2 ;

[0046] Example 5

[0047] The average molecular weight of the perfluoropolyether in this embodiment is 6000 Da;

[0048] In this embodiment, the particle size of the nano-magnesium hydroxide is 1 μm;

[0049] First, mix 30 ml of nonafluorobutyl methyl ether solvent into 60 ml of perfluoropentanone solvent, stir mechanically until homogeneous at 800 r / min for 20 min, add 10 ml of perfluoropolyether, stir mechanically until homogeneous at 800 r / min for 20 min, add 1 g of nano magnesium carbonate, and disperse evenly using an ultrasonic disperser at 1000 W for 10 min.

[0050] Place the above paper deacidification solution in a 250ml beaker, immerse the paper in the deacidification solution for 20 minutes, remove the treated paper and air dry it naturally in a fume hood;

[0051] The paper used in this embodiment is a page from an ancient book, weighing 3g, with a basis weight of 30g / m³. 2 ;

[0052] According to the relevant national standards GB / T13528-1992 Determination of pH value of paper and paperboard surface and GB / T24998-2010 Determination of alkali content of paper and paperboard, the paper deacidification effect of the anhydrous nano-mixed solvent deacidification solutions prepared in Examples 1, 2, 3, 4 and 5 was tested. The results of the paper deacidification test are shown in Table 1.

[0053] Table 1

[0054]

[0055]

[0056] According to the relevant national standard GB / T 12914-2018 Determination of Tensile Strength of Paper and Paperboard, the paper deacidification effect of the anhydrous nano-mixed solvent deacidification solutions prepared in Examples 1, 2, 3, 4 and 5 was tested. The results of the paper deacidification test are shown in Table 2.

[0057] Table 2

[0058]

[0059] Simultaneously, the surface electrostatic potentials of perfluoroether and perfluoroketone solvent molecules were measured. The results showed that perfluoroethers had a positive surface charge on the methyl group connecting the ether bond, while perfluoroketones had a negative surface charge on the oxygen atom on the carbonyl group, proving that the two could interact through charge. Color difference, tensile strength, and changes in handwriting were tested on the paper before and after deacidification. The results were as follows: the paper treated with the deacidification solutions prepared in Examples 1-5 showed color difference changes ΔE less than 2, tensile strength changes less than 1.8%, and no visible damage or breakage. No visible changes were observed in the printed handwriting. Fourier transform infrared spectroscopy showed that no fluorine-containing functional groups were introduced onto the surface of the treated paper.

[0060] In summary, this invention, through a technical solution involving the mixing of perfluoroether and perfluoroketone solvents with opposite molecular surface electrostatic potentials, followed by the addition of long-chain perfluoropolyethers for further processing, effectively avoids problems caused by the residue of surfactants such as fluorinated carboxylic esters and fluorinated silanes on paper. Furthermore, it leverages the steric hindrance effect of long-chain molecules to obtain a paper deacidification solution with excellent suspension properties and system stability. Simultaneously, the fluorinated organic solvents used are low-cost, and the prepared paper deacidification solution is suitable for large-scale deacidification. After deacidification, the paper not only possesses a suitable pH value but also forms a certain alkali reserve, providing long-term protection for the paper, thus exhibiting significant economic and practical value.

[0061] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A paper deacidification solution, characterized in that, It consists of a fluorocarbon deacidification solution and an alkaline deacidifying agent; wherein the fluorocarbon deacidification solution is composed of a perfluoropolyether solvent, a perfluoroether solvent, and a perfluoroketone solvent, wherein the perfluoropolyether solvent accounts for 1-10% of the volume percentage of the fluorocarbon deacidification solution, the perfluoroether solvent accounts for 10-30% of the volume percentage of the fluorocarbon deacidification solution, and the perfluoroketone solvent accounts for 60-89% of the volume percentage of the fluorocarbon deacidification solution; the alkaline deacidifying agent is an alkaline earth metal compound nanoparticle, and the mass ratio of the alkaline deacidifying agent to the volume of the fluorocarbon deacidification solution is 0.1-10 g / L.

2. The paper deacidification solution according to claim 1, characterized in that... The perfluoropolyether solvent is a perfluoropolyether with an average molecular weight of 800 to 6000 Da.

3. The paper deacidification solution according to claim 1, characterized in that... The perfluoroether solvent is one or more of perfluorobutyl methyl ether, methyl nonafluorobutyl ether, or hexafluoropropyl methyl ether.

4. The paper deacidification solution according to claim 1, characterized in that... The perfluoroketone solvent is one or both of perfluorohexanone or perfluoropentanone.

5. The paper deacidification solution according to claim 1, characterized in that... The alkaline earth metal compound is one or more of alkaline earth metal hydroxides, alkaline earth metal carbonates, or alkaline earth metal bicarbonates.

6. The paper deacidification solution according to claim 1, characterized in that... The alkaline earth metal in the alkaline earth metal compound is one or more of magnesium, calcium, or zinc.

7. The paper deacidification solution according to claim 1, characterized in that... The alkaline earth metal compound nanoparticles have a particle size of 10 nm to 1 μm.

8. A method for preparing the paper deacidification solution as described in claim 1, characterized in that, The preparation method includes the following steps: First, a perfluoroether solvent is mixed into a perfluoroketone solvent and mechanically stirred until homogeneous at a speed of 200-800 r / min for 5-20 min; then, a perfluoropolyether is added and mechanically stirred until homogeneous at a speed of 200-800 r / min for 5-20 min; finally, an alkaline deacidifying agent is added and dispersed evenly using an ultrasonic disperser at an ultrasonic power of 200-1000 W for 10-30 min.

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