Paper reinforcing liquid, its preparation method and application

Abstract

The application discloses a paper reinforcing liquid and a preparation method and application thereof. According to mass percentage, the paper reinforcing liquid comprises the following components: 0.1-20wt% of bacterial cellulose, 2-50wt% of N-methylmorpholine-N-oxide, 0.01-0.5wt% of an antioxidant and the rest of an organic solvent. The paper reinforcing liquid has good storage stability, and the paper obtained by using the paper reinforcing liquid in paper (especially paper cultural relics) reinforcement is not prone to deformation, wrinkling and other problems; in addition, the paper reinforcing liquid can be used for batch processing of books and other multi-page paper cultural relics.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paper document protection. More particularly, it relates to a paper reinforcing liquid, a preparation method and application thereof. BACKGROUND

[0002] There are a large number of paper documents such as ancient books and rare books, which have great value. However, due to the variety of papermaking raw materials, combined with war, water, fire, and insect damage, many ancient books and rare books have become brittle or even crumbled into paper scraps. In 2003, the National Library conducted a sampling survey on the acidity and preservation status of paper documents in its collection, and found that the proportion of Song and Yuan rare books reaching moderate and severe aging damage was 50%, the proportion of Ming rare books reaching moderate and severe aging damage was 28%, and the proportion of Qing rare books reaching mild aging damage was more than 70%. According to the “Ancient Book Special Collection Damage Grading Standard” (WH / T 22-2006), if the ancient books show “severe paper aging, severe reduction of paper mechanical strength, and phenomena such as dropping, cracking, and breaking of book leaves when turning”, it is considered as first-level damage.

[0003] Once the paper documents such as ancient books become brittle, they cannot provide normal reading function, and it is often difficult to carry out dust removal, deacidification, repair and other protection measures, which is not conducive to the inheritance and active use of ancient books. It is particularly important to reinforce the brittle ancient books.

[0004] CN 105970733 A discloses a method for improving the paper strengthening effect of bacterial cellulose-based paper strengthening agent. The quaternary ammonium salt cationization modification of bacterial cellulose can greatly improve the effect of bacterial cellulose on the enhancement of paper physical properties, or reduce the amount of bacterial cellulose while achieving the same enhancement effect. CN 111622015 A discloses a preparation method and application of a paper deacidification and strengthening repair liquid based on bacterial cellulose. The deacidification and strengthening repair liquid of the invention is composed of bacterial cellulose or its derivatives, alkali and aqueous solution. CN 113802411 A discloses a preparation method of a multifunctional paper repair liquid based on bacterial cellulose-based alkaline nanoparticles and its application in aging paper repair. The paper is treated for deacidification, strengthening and antibacterial treatment.

[0005] Most of the existing reinforcement methods are aqueous systems, which can cause some ink to spread, and the treated paper is prone to deformation, wrinkling and other problems. In addition, these aqueous systems need to be used within a short period of time. In addition, for a whole book, the book needs to be disassembled and bound into single-page paper for reinforcement treatment, which is difficult to handle in batches for the whole book. For libraries, archives and other units with a large number of books, this undoubtedly increases the difficulty of work. SUMMARY

[0006] Based on the above facts, the purpose of the present application is to provide a paper reinforcing liquid and its preparation method and application, so as to overcome the problems of deformation, wrinkling and the like of the treated paper in the existing paper (especially paper cultural relics) reinforcing method, and the problem of difficult batch processing of the whole cultural relics; in addition, the paper reinforcing liquid has good storage stability.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] On the one hand, the present application provides a paper reinforcing liquid, which comprises the following components in terms of mass percentage:

[0009] 0.1-20wt% of bacterial cellulose, 2-50wt% of N-methylmorpholine-N-oxide, 0.01-0.5wt% of antioxidant and the rest of organic solvent.

[0010] The N-O bond in the N-methylmorpholine-N-oxide has strong polarity, and the oxygen atom forms a hydrogen bond with the hydroxyl group of the bacterial cellulose through a lone pair of electrons, thereby destroying the original hydrogen bond between the cellulose molecules and reducing the interaction between the cellulose molecules, so as to completely dissolve the bacterial cellulose.

[0011] Further, the antioxidant is selected from one or more of the following: tert-butyl hydroquinone, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-hydroxymethyl phenol, propyl gallate, octyl gallate, lauryl gallate and isoamyl gallate. The antioxidant can prevent the generation of free radicals in the paper reinforcing liquid, thereby improving the reinforcing effect on the paper cultural relics.

[0012] Further, the addition amount of the exemplary antioxidant in the paper reinforcing liquid includes but is not limited to 0.01wt%, 0.1wt%, 0.04wt%, 0.4wt% and the like.

[0013] Further, the organic solvent is selected from one or more of the following: ethylene glycol, N,N-dimethylformamide, dimethyl sulfoxide, castor oil and turpentine. The organic solvent can dissolve N-methylmorpholine-N-oxide and promote the swelling or dissolution of bacterial cellulose, thereby making the obtained paper reinforcing liquid not cause deformation, wrinkling and the like of the treated paper after reinforcing the paper cultural relics. Preferably, the organic solvent is selected from dimethyl sulfoxide or a mixture of dimethyl sulfoxide and ethylene glycol (the mixing ratio is preferably 1:1.45-1:2). At this time, the reinforcing effect is more optimal.

[0014] Further, the mass ratio of the bacterial cellulose to N-methylmorpholine-N-oxide is 1:6.5-20. At this time, the paper reinforcing solution obtained has good reinforcing effect, and the paper cultural relics reinforced by the paper reinforcing solution are not prone to deformation, wrinkling and other problems. Exemplary mass ratios of the bacterial cellulose to N-methylmorpholine-N-oxide include but are not limited to 1:9-20, 1:6.5-9.5, 1:6.7, 1:9, 1:20, etc.

[0015] Further, the bacterial cellulose is produced by fermentation of microorganisms such as Acetobacter, Alcaligenes, Sarcina, Rhizobium, Pseudomonas, Azotobacter and Aerobacter.

[0016] Further, the molecular structure of the bacterial cellulose is a high-molecular polymer formed by β-glucose combined by β-1,4-glucoside bond. The bacterial cellulose has the same chemical composition as cellulose of the paper cultural relics, and is more in line with the principles of “restoring to original state as much as possible” and “minimum intervention” required in the field of paper cultural relics protection than other types of modified cellulose or cellulose derivatives.

[0017] Further, the degree of polymerization of the bacterial cellulose is 200-20000.

[0018] Further, in the paper reinforcing solution, exemplary mass percentage contents of the bacterial cellulose include but are not limited to 0.4-5.4wt%, 0.4-0.8wt%, 0.83-5.4wt%, 0.83-4.7wt%, 0.83-2wt%, 0.83-5.3wt%, 0.83-4.7wt%, 0.83wt%, 5.3wt%, etc.

[0019] Further, in the paper reinforcing solution, exemplary mass percentage contents of the N-methylmorpholine-N-oxide include but are not limited to 13-50wt%, 13-48wt%, 16.53-48wt%, 16.53-31.3wt%, 16.53wt%, 48wt%, etc.

[0020] In another aspect, the present application provides a preparation method of the paper reinforcing solution as described above, comprising the following steps:

[0021] The bacterial cellulose is added into the organic solvent containing N-methylmorpholine-N-oxide, and is stirred for the first time until uniform, and then an antioxidant is added and stirred for the second time to obtain the paper reinforcing solution.

[0022] The first stirring can make the bacterial cellulose swell. Further, the stirring temperature of the first stirring is 60-90℃, the stirring time is 0.5-1h, and the stirring speed is 50-200rpm.

[0023] The second stirring is for dissolving the bacterial cellulose. If the stirring temperature / vacuum degree is too low, the bacterial cellulose cannot be dissolved, and if the stirring temperature / vacuum degree is too high, the bacterial cellulose can be decomposed. The stirring time is determined according to the state of dissolution. If the stirring time is too short, the bacterial cellulose cannot be completely dissolved, and if the stirring time is too long, side reactions increase. If the stirring speed is too low, the dissolution process is not uniform, and if the stirring speed is too high, the "pole-climbing effect" occurs, which is not conducive to dissolution. Further, the stirring temperature of the second stirring is 90-105℃, the stirring time is 0.5-2h, the stirring speed is 200-800rpm, and the pressure is 0-200mbar.

[0024] In another aspect, the present application provides the use of the paper reinforcing solution as described above in reinforcing paper cultural relics.

[0025] Further, the use comprises the following steps:

[0026] applying the paper reinforcing solution to the surface of the paper cultural relic;

[0027] immersing the paper cultural relic to which the paper reinforcing solution is applied in a regenerating solvent, and drying, to obtain the reinforced paper cultural relic.

[0028] Further, the paper cultural relic can be a single-page or multi-page paper cultural relic, including but not limited to books and archives, such as ancient books and modern and contemporary documents. The paper of the paper cultural relic is made of plant fibers, and the chemical composition is cellulose, and the molecular structure is a high-molecular polymer formed by β-glucose combined by β-1,4-glucoside bonds, and the degree of polymerization is 200-2000. In some specific examples, the material of the paper cultural relic is rice paper.

[0029] Further, the application method is coating or immersion.

[0030] Further, the coating method is brushing or spraying.

[0031] The regenerating solvent can completely or partially dissolve the components in the paper reinforcing solution other than the bacterial cellulose.

[0032] Further, the regenerating solvent is selected from one or more of water, ethanol, isopropanol, glycerol, ethylene glycol, N,N-dimethylformamide, dimethyl sulfoxide, castor oil, and turpentine.

[0033] Further, after the paper reinforcing solution is applied to the surface of the paper cultural relic, it is kept at 20-90℃ for 5-30min, and then immersed in the regenerating solvent.

[0034] Further, the number of immersions is one or more, and the temperature of each immersion is 20-90℃, and the time of each immersion is 5-30min.

[0035] Further, the application method can be used to reinforce single or multiple pages of paper relics.

[0036] When multiple pages of paper relics need to be reinforced, plastic separators can be inserted between each page of the paper relics to be reinforced, and then the paper reinforcement liquid is applied to the surface of the paper relics with plastic separators and subsequent processing is performed.

[0037] The plastic separator has certain stability during the reinforcement process.

[0038] Further, the plastic separator is selected from one or more of polyethylene, polyvinyl chloride, polypropylene and polystyrene.

[0039] The beneficial effects of the present application are as follows:

[0040] The paper reinforcement liquid provided in the present application does not contain water, and through the selection of each component of the raw material and the determination of the amount of each component, the obtained paper reinforcement liquid has good stability, can have the optimal reinforcement effect on paper relics for at least 20 days at room temperature, and does not significantly affect the whiteness and hand feeling of the paper, the dried paper is not wrinkled and deformed, and the reinforcement treatment of the entire book can be realized without disassembling and binding, and can be widely applied to the reinforcement and protection field of valuable paper relics such as ancient books, modern literature and the like. DETAILED DESCRIPTION

[0041] In order to more clearly illustrate the present application, the present application will be further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the specific description below is illustrative and not limiting, and should not limit the protection scope of the present application.

[0042] Example 1

[0043] A paper reinforcement liquid, the preparation method thereof comprises the following steps:

[0044] 10.0g of bacterial cellulose with a degree of polymerization of 1500 is slowly added to 87.5g of dimethyl sulfoxide containing 90g of N-methylmorpholine-N-oxide, stirred at 70℃ at a speed of 100rpm for 0.5h; then 0.07g of propyl gallate is added, stirred at 90℃, 180mbar at a speed of 500rpm for 1h, to obtain the paper reinforcement liquid.

[0045] The above-mentioned paper reinforcement liquid is used to reinforce paper relics, and the application method comprises the following steps:

[0046] The paper reinforcing solution at 60℃ is applied to the front of the rice paper by brushing, and then the treated rice paper is kept at 60℃ for 10 min, and then the treated rice paper is soaked in ethanol at 25℃ for 15 min twice, and finally the treated rice paper is completely dried at 80℃, so that the reinforcing treatment is completed.

[0047] The formula of the paper reinforcing solution is shown in Table 1, and the reinforcing effect is shown in Table 2.

[0048] After the paper reinforcing solution is prepared, it is continuously placed at room temperature for 20 days, and the appearance of the paper reinforcing solution does not change, and the above application is repeated after the paper reinforcing solution is placed at room temperature for 20 days, and the experimental results are similar to the above results, the difference is within the error range (±5%), which reflects good stability.

[0049] Example 2

[0050] A paper reinforcing solution, the preparation method thereof comprises the following steps:

[0051] 1.2g of bacterial cellulose with a degree of polymerization of 1500 is slowly added to 250g of N,N-dimethylformamide containing 39.6g of N-methylmorpholine-N-oxide, stirred at 80℃ at a speed of 150rpm for 1h; then 0.29g of 2,6-di-tert-butyl-p-cresol is added, stirred at 80℃ at a speed of 300rpm under 120mbar for 0.8h, to obtain the paper reinforcing solution.

[0052] The above paper reinforcing solution is used for reinforcing paper cultural relics, and the application method comprises the following steps:

[0053] The rice paper is fully soaked in the paper reinforcing solution at 40℃, and then the treated rice paper is kept at 40℃ for 20min, and then the treated rice paper is soaked in dimethyl sulfoxide at 20℃ for 10min twice, and finally the treated rice paper is completely dried at 50℃, so that the reinforcing treatment is completed.

[0054] The formula of the paper reinforcing solution is shown in Table 1, and the reinforcing effect is shown in Table 2.

[0055] After the paper reinforcing solution is prepared, it is continuously placed at room temperature for 20 days, and the appearance of the paper reinforcing solution does not change, and the above application is repeated after the paper reinforcing solution is placed at room temperature for 20 days, and the experimental results are similar to the above results, the difference is within the error range (±5%), which reflects good stability.

[0056] Example 3

[0057] A paper reinforcing solution, the preparation method thereof comprises the following steps:

[0058] Slowly add 2.9 g of bacterial cellulose with a degree of polymerization of 2000 to 300 g of dimethyl sulfoxide containing 60 g of N-methylmorpholine-N-oxide, stir at 70 °C at a speed of 100 rpm for 0.5 h; then add 0.06 g of lauryl gallate, stir at 90 °C, 180 mbar, at a speed of 500 rpm for 1 h, to obtain the paper reinforcing solution.

[0059] The above paper reinforcing solution is used to reinforce paper cultural relics, and the application method comprises the following steps:

[0060] Use the paper reinforcing solution at 60 °C to brush the front of the rice paper, then keep the treated rice paper at 60 °C for 10 min, then immerse the treated rice paper in isopropanol at 25 °C for 15 min twice, and finally completely dry the treated rice paper at 80 °C to complete the reinforcement treatment.

[0061] The formula of the paper reinforcing solution is shown in Table 1, and the reinforcement effect is shown in Table 2.

[0062] After the preparation of the paper reinforcing solution is completed, continue to place it at room temperature for 20 days, the appearance of the paper reinforcing solution does not change, and the paper reinforcing solution is placed at room temperature for 20 days, and the above application is repeated, the experimental results are similar to the above results, the difference is within the error range (± 5%), which reflects good stability.

[0063] Example 4

[0064] A paper reinforcing solution, the preparation method thereof comprises the following steps:

[0065] Slowly add 18 g of bacterial cellulose with a degree of polymerization of 500 to 100 g of dimethyl sulfoxide containing 121 g of N-methylmorpholine-N-oxide and 145 g of ethylene glycol, stir at 60 °C at a speed of 100 rpm for 0.5 h; then add 1.54 g of propyl gallate, stir at 60 °C, 180 mbar, at a speed of 500 rpm for 1 h, to obtain the paper reinforcing solution.

[0066] The above paper reinforcing solution is used to reinforce paper cultural relics, and the application method comprises the following steps:

[0067] Use the paper reinforcing solution at 50 °C to brush the front of the rice paper, then keep the treated rice paper at 50 °C for 10 min, then immerse the treated rice paper in water at 25 °C for 15 min, then immerse the treated rice paper in ethanol at 25 °C for 15 min, and finally completely dry the treated rice paper at 50 °C to complete the reinforcement treatment.

[0068] The formula of the paper reinforcing solution is shown in Table 1, and the reinforcement effect is shown in Table 2.

[0069] After the paper reinforcing solution is prepared, it is continuously placed at room temperature for 20 days, and the appearance of the paper reinforcing solution does not change. The above application is repeated after the paper reinforcing solution is placed at room temperature for 20 days, and the experimental results are similar to the above results, with a difference within the error range (±5%), which reflects good stability.

[0070] Example 5

[0071] A paper reinforcing solution, a preparation method thereof includes the following steps:

[0072] 30 g of bacterial cellulose with a degree of polymerization of 2000 is slowly added to 2000 g of ethylene glycol and 1000 g of dimethyl sulfoxide containing 600 g of N-methylmorpholine-N-oxide, stirred at 75°C at a speed of 150 rpm for 0.5 h; then 0.5 g of propyl gallate is added, stirred at 95°C, 60 mbar, at a speed of 300 rpm for 1 h, to obtain a paper reinforcing solution.

[0073] The above paper reinforcing solution is used for reinforcing paper cultural relics, and the application method includes the following steps:

[0074] The paper is fully soaked in the paper reinforcing solution at 60°C, and then the treated paper is kept at 60°C for 20 min. Then the treated paper is soaked in glycerol at 40°C for 30 min, and then soaked in ethanol at 40°C for 30 min. Finally, the treated paper is completely dried at 60°C to complete the reinforcing treatment.

[0075] The formula of the paper reinforcing solution is shown in Table 1, and the reinforcing effect is shown in Table 2.

[0076] After the paper reinforcing solution is prepared, it is continuously placed at room temperature for 20 days, and the appearance of the paper reinforcing solution does not change. The above application is repeated after the paper reinforcing solution is placed at room temperature for 20 days, and the experimental results are similar to the above results, with a difference within the error range (±5%), which reflects good stability.

[0077] Example 6

[0078] A paper reinforcing solution, a preparation method thereof includes the following steps:

[0079] 20 g of bacterial cellulose with a degree of polymerization of 500 is slowly added to 138 g of dimethyl sulfoxide and 200 g of ethylene glycol containing 307 g of N-methylmorpholine-N-oxide, stirred at 70°C at a speed of 100 rpm for 0.5 h; then 2 g of octyl gallate is added, stirred at 650°C, 180 mbar, at a speed of 500 rpm for 1 h, to obtain a paper reinforcing solution.

[0080] The above paper reinforcing solution is used for reinforcing paper cultural relics, and the application method includes the following steps:

[0081] First, polypropylene plastic diaphragm is inserted between each page of the book, then the book is fully soaked in paper reinforcement liquid at 30℃, then the treated book is kept at 30℃ for 40 min, then the treated book is soaked in methanol at 25℃ for 30 min, then the treated book is soaked in isopropanol at 25℃ for 30 min, finally the treated book is completely dried at 65℃, and the polypropylene plastic diaphragm is removed, so the reinforcement treatment is completed.

[0082] The formula of the paper reinforcement liquid is shown in Table 1, and the reinforcement effect is shown in Table 2.

[0083] After the paper reinforcement liquid is prepared, it is continuously placed at room temperature for 20 days, and the appearance of the paper reinforcement liquid does not change, and the paper reinforcement liquid is repeatedly applied after being placed at room temperature for 20 days, and the experimental results are similar to the above results, the difference is within the error range (±5%), which reflects good stability.

[0084] Example 7

[0085] Example 4 is repeated, except that the formula of the paper reinforcement liquid is shown in Table 1, and the reinforcement effect is shown in Table 2.

[0086] Comparative Example 1

[0087] A paper reinforcement liquid, the preparation method thereof comprises the following steps:

[0088] 2.0 g of bamboo fiber pulp with a degree of polymerization of 500 is slowly added to 150 g of N,N-dimethylformamide containing 30 g of N-methylmorpholine-N-oxide, stirred at 60℃ at a speed of 100 rpm for 0.5 h; then 0.02 g of lauryl gallate is added, stirred at 80℃, 150 mbar at a speed of 500 rpm for 1 h, to obtain a paper reinforcement liquid.

[0089] The reinforcement of paper relics by the above-mentioned paper reinforcement liquid comprises the following steps:

[0090] The paper reinforcement liquid at 45℃ is applied to the front of the rice paper by brushing, then the treated rice paper is kept at 45℃ for 10 min, then the treated rice paper is soaked in water at 25℃ for 15 min, then the treated rice paper is soaked in ethanol at 25℃ for 30 min, and finally the treated rice paper is completely dried at 70℃, so the reinforcement treatment is completed.

[0091] The formula of the paper reinforcement liquid is shown in Table 1, and the reinforcement effect is shown in Table 2.

[0092] Comparative Example 2

[0093] A paper reinforcement liquid, the preparation method thereof comprises the following steps:

[0094] 10g of bacterial cellulose with a degree of polymerization of 1500 was added to 990g of deionized water, and left to swell for 6h, then treated by high pressure homogenization at 45MPa for 30min, and treated by high speed homogenization at 15000r / min for 5min, to obtain a bacterial cellulose water dispersion.

[0095] The above bacterial cellulose water dispersion is used to reinforce paper cultural relics, and the application method comprises the following steps:

[0096] First, a polypropylene plastic diaphragm is inserted between each page of the book, then the book is fully soaked with the bacterial cellulose water dispersion at 25℃, then dried at 65℃ for 24h, then treated by flat pressing under a pressure of 10kg for 24h, and finally the polypropylene plastic diaphragm is removed.

[0097] The formula of the bacterial cellulose water dispersion is shown in Table 1, and the reinforcement effect is shown in Table 2.

[0098] Comparative Example 3

[0099] Example 1 is repeated, except that the bacterial cellulose is replaced by nanocellulose, and the other conditions remain unchanged, to prepare a paper reinforcement liquid; the application is carried out in the manner of Example 1, and the reinforcement effect is shown in Table 2.

[0100] Comparative Example 4

[0101] Example 1 is repeated, except that N-methyl morpholine-N-oxide is not added, and the bacterial cellulose cannot be dissolved.

[0102] Table 1 Formula of the paper reinforcement liquid in each example and comparative example

[0103]

[0104] Note: * indicates that the cellulose in the formula is bamboo fiber pulp.

[0105] ** indicates that the solvent in the formula is water.

[0106] Table 2 Reinforcement effect obtained by each example and comparative example

[0107]

[0108] Obviously, the above examples of the present application are merely examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application still fall within the protection scope of the present application.

Claims

1. The application of a paper-reinforcing liquid in the reinforcement of paper cultural relics, characterized in that, The paper strengthening liquid comprises the following components by weight percentage: 0.1-20 wt% bacterial cellulose, 2-50 wt% N-methylmorpholine-N-oxide, 0.01-0.5 wt% antioxidant and balance organic solvent; The paper strengthening solution does not contain water; The mass ratio of bacterial cellulose to N-methylmorpholine-N-oxide is 1:6.5-20; The application includes the following steps: The paper-reinforcing liquid is applied to the surface of the paper artifact; The paper artifact with the paper reinforcement liquid applied is then immersed in a recycled solvent and dried to obtain the reinforced paper artifact. The regenerated solvent is selected from one or more of ethanol, isopropanol, glycerol, ethylene glycol, N,N-dimethylformamide, and dimethyl sulfoxide.

2. The application according to claim 1, characterized in that, The antioxidant is selected from one or more of tert-butylhydroquinone, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-hydroxymethylphenol, propyl gallate, octyl gallate, lauryl gallate, and isoamyl gallate; and / or The organic solvent is selected from one or more of ethylene glycol, N,N-dimethylformamide, and dimethyl sulfoxide.

3. The application according to claim 1, characterized in that, The preparation method of the paper strengthening liquid includes the following steps: Bacterial cellulose was added to an organic solvent containing N-methylmorpholine-N-oxide, and stirred for the first time until homogeneous. Then, an antioxidant was added, and the mixture was stirred for the second time to obtain the paper reinforcement solution.

4. The application according to claim 3, characterized in that, The first stirring is performed at a temperature of 60-90℃, for a time of 0.5-1 hour, and at a speed of 50-200 rpm; and / or The second stirring is carried out at a temperature of 90-105℃, a stirring time of 0.5-2h, a stirring speed of 200-800rpm, and a pressure of 0-200mbar.

5. The application according to claim 1, characterized in that, The application method is coating or soaking.

6. The application according to claim 5, characterized in that, The coating method is brushing or spraying.

7. The application according to claim 1, characterized in that, After applying the paper-reinforcing liquid to the surface of the paper artifact, maintain it at 20-90℃ for 5-30 minutes, and then immerse it in a regenerating solvent; and / or The soaking can be done once or multiple times, with each soaking temperature being 20-90℃ and the time being 5-30 minutes.

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