Aging-resistant polysaccharide-based adhesive as well as preparation method and application thereof, and paper fracture mouth repairing method

Abstract

This invention relates to the field of paper processing technology, specifically to an aging-resistant polysaccharide-based adhesive, its preparation method and application, and a method for repairing paper tears. The aging-resistant polysaccharide-based adhesive provided by this invention comprises β-1,3-glucan, galactomannan, xylan, calcium carbonate, natural polysaccharide additives, and water; the pH value of the aging-resistant polysaccharide-based adhesive is 7-8.5. The components of the aging-resistant polysaccharide-based adhesive provided by this invention work synergistically, exhibiting good adhesion to both smooth cuts and tears in paper. Furthermore, the tensile strength after bonding is further increased after accelerated aging treatment, demonstrating excellent aging resistance. In addition, the adhesive also has a certain deacidification ability and does not contain organic solvents or synthetic polymers, making it particularly suitable for repairing tears in paper artifacts.

Description

Technical Field

[0001] This invention relates to the field of paper processing technology, specifically to an aging-resistant polysaccharide-based adhesive, its preparation method and application, and a method for repairing paper tears. Background Technology

[0002] Museum-collected paper artifacts are cultural relics made of paper and printing inks, held by collecting institutions. These include books, newspapers, archives, drawings, maps, rubbings, banknotes, documents, stamps, etc. Among them, calligraphy and paintings are the most representative, non-renewable, and of significant cultural and historical importance. During long-term preservation, paper artifacts inevitably suffer damage from physical, chemical, biological, and human factors, resulting in paper artifact defects. Among the more than 20 common defects, paper tearing severely damages the structural integrity of paper artifacts, seriously affecting their long-term preservation. Protective restoration of torn paper is of great significance for the long-term preservation of paper artifacts.

[0003] For the repair of tears in paper artifacts, thin paper and adhesives are typically used. Unlike conventional paper bonding, paper artifacts have extremely stringent requirements regarding the durability, reversibility, and transparency of adhesives, while also requiring a neutral or slightly alkaline pH (7 ≤ pH ≤ 8.5) to avoid introducing the risk of acidification. For precious paper artifacts, the field of cultural relic conservation usually chooses natural polymers as adhesives, avoiding the use of synthetic polymers or modified materials that could cause irreversible damage. Traditional materials such as chitosan, cellulose, starch, and gelatin all have certain performance defects. Chitosan and cellulose have poor solubility and are difficult to pre-treat; their strength as adhesives alone is limited, and they often exhibit color differences from the paper artifact after drying. Starch has a retrogradation problem, making it difficult to effectively bond tears with high strength. Gelatin aqueous solutions are slightly acidic, posing a risk of acidification to paper artifacts. To address these issues, developing adhesives that do not rely on thin paper, have good bonding effects, are reversible, and are slightly alkaline will greatly overcome the technical bottlenecks in the repair of tears in paper artifacts. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide an aging-resistant polysaccharide-based adhesive, its preparation method and application, and a method for repairing paper tears. The aging-resistant polysaccharide-based adhesive provided by this invention is neutral or weakly alkaline, and has the characteristics of good adhesion, good film properties, high transparency, and high reversibility, eliminating the need for reinforcing the tear with materials such as thin paper.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides an aging-resistant polysaccharide-based adhesive, characterized in that it comprises β-1,3-glucan, galactomannan, xylan, calcium carbonate, natural polysaccharide additives, and water; The pH value of the aging-resistant polysaccharide-based adhesive is 7~8.5.

[0006] Preferably, in the aging-resistant polysaccharide-based adhesive, the concentration of β-1,3-glucan is 0.1~40 g / L, the concentration of galactomannan is 0.1~40 g / L, the concentration of xylan is 0.1~50 g / L, the concentration of calcium carbonate is 0.01~2 g / L, and the concentration of natural polysaccharide auxiliaries is 0.01~25 g / L.

[0007] Preferably, the galactomannan includes one or more of locust bean gum, tara gum, and fenugreek gum.

[0008] Preferably, the natural polysaccharide adjuvant includes one or more of pullulan, xanthan gum, and gellan gum.

[0009] This invention also provides a method for preparing the aging-resistant polysaccharide-based adhesive described in the above technical solution, comprising the following steps: β-1,3-glucan was dissolved in an alkaline solution, the pH was adjusted to 7-8.5, solid and liquid were separated, and the obtained solid component was mixed with water to obtain β-1,3-glucan colloid. Galactomannan, a first inorganic strong base, and water are mixed, subjected to a first heat treatment, and the pH value is adjusted to 7-8.5. Solid-liquid separation is performed, the resulting liquid component is subjected to a first alcohol precipitation, and the resulting first alcohol precipitate is dissolved in water to obtain a galactomannan solution. Xylan, a second inorganic strong base, and water are mixed, subjected to a second heat treatment, and the pH value is adjusted to 7-8.5. Solid-liquid separation is performed, and the resulting liquid component is subjected to a second alcohol precipitation. The resulting second alcohol precipitate is dissolved in water to obtain a xylan solution. The natural polysaccharide auxiliaries, the third inorganic strong base, and water are mixed, subjected to a third heat treatment, and the pH value is adjusted to 7-8.5. The solid and liquid components are separated, and the resulting liquid component is subjected to a third alcohol precipitation. The resulting third alcohol precipitate is dissolved in water to obtain the auxiliary solution. The β-1,3-glucan colloid, galactomannan solution, xylan solution, auxiliary agent solution, calcium carbonate powder and water are mixed and the pH is adjusted to 7-8.5 to obtain the aging-resistant polysaccharide-based adhesive.

[0010] Preferably, the alkaline solution includes one or more of sodium hydroxide solution, potassium hydroxide solution, and saturated calcium hydroxide solution.

[0011] Preferably, the first strong base, the second strong base, and the third strong base independently include one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide; The mass ratio of the galactomannan to the first inorganic strong base is 10~20:1; The mass ratio of the xylan to the second inorganic strong base is 10~20:1; The mass ratio of the natural polysaccharide auxiliary agent to the third inorganic strong base is 10~20:1; The temperatures for the first, second, and third heat treatments are independently 105~125℃, and the times are independently 5~20min; The alcohols used for the first, second, and third alcohol precipitations independently include one or more of ethanol, methanol, and propanol; In the first, second, and third alcohol precipitation processes, the volume fraction of alcohol is 60-90%, the single alcohol precipitation time is 1-3 hours, and the number of alcohol precipitations is 2-5 times independently.

[0012] The present invention also provides the application of the aging-resistant polysaccharide-based adhesive described in the above technical solution or the aging-resistant polysaccharide-based adhesive prepared by the above technical solution in the repair of paper tears.

[0013] This invention also provides a method for repairing paper tears, comprising the following steps: laying the paper to be repaired flat on a smooth plate, wetting the paper tear with water, manually piecing the paper together so that the two sides of the tear are neat and without misalignment, applying adhesive to the tear and then letting it dry; the adhesive is the aging-resistant polysaccharide-based adhesive described in the above technical solution or the aging-resistant polysaccharide-based adhesive prepared by the preparation method described in the above technical solution.

[0014] Preferably, the amount of adhesive used at the crack is 25~50 μL / cm.

[0015] This invention utilizes the synergistic effects of the unique physicochemical properties and inter-polysaccharide interactions of polysaccharides from different sources, including β-1,3-glucan, galactomannan, xylan, and natural polysaccharide additives, to create an aging-resistant polysaccharide-based adhesive with excellent adhesive properties, suitable for repairing tears in paper artifacts. The aging-resistant polysaccharide-based adhesive provided by this invention exhibits good film-forming properties and high transparency, effectively bonding to smooth cuts and tears in paper without the need for reinforcement with thin paper or other materials, and maintaining good adhesion even after accelerated aging. Except for calcium carbonate, all other raw materials in the aging-resistant polysaccharide-based adhesive provided by this invention are highly biocompatible natural polysaccharides, without the introduction of any synthetic polymers, chemically modified polysaccharides, or organic solvents, meeting the stringent material requirements for paper artifacts. Furthermore, the aging-resistant polysaccharide-based adhesive provided by this invention can be peeled off after being wetted with water, demonstrating good reversibility.

[0016] The preparation method provided by this invention can effectively remove impurities such as proteins and modifying groups on polysaccharide molecules from polysaccharide samples (β-1,3-glucan, galactomannan, xylan, and natural polysaccharide additives), significantly preventing paper yellowing. Furthermore, calcium carbonate is an important material for deacidifying paper artifacts; in addition to repairing tears, it also helps deacidify the paper, further enhancing the beneficial effects of the adhesive. Attached Figure Description

[0017] Figure 1 To test the bonding effect of adhesive #3 in Example 1 on a smooth cut with irregular tears, where A represents the bonding effect and B represents the film transparency; Figure 2 The figure shows the tensile strength test results of adhesives #1 to #4 in Test Example 4 after accelerated aging treatment on the smooth cut of raw Xuan paper repaired with these adhesives. Figure 3 The figure shows the effect of calcium carbonate content (adhesives #2 and #8~ #10) in the aging-resistant polysaccharide-based adhesives in Test Example 5 on the tensile strength of the smooth cut of raw Xuan paper after accelerated aging treatment. Figure 4 The image shows a scanning electron microscope (SEM) image of the fracture area after the repair of a smooth incision with adhesive #2 on raw Xuan paper in Example 6. Figure 5 The image shows a scanning electron microscope (SEM) image of the fracture area after the repair of a smooth incision with adhesive #4 from raw Xuan paper in Example 6. Figure 6 The image shows a scanning electron microscope (SEM) image of the fracture area after the adhesive prepared in Example 6 (12#) repaired a smooth incision in raw Xuan paper. Figure 7 The graph shows the trend of the transverse tensile strength of the paper as a function of deformation after repairing the tear in the raw Xuan paper with adhesive #4 and adhesive #13 in Test Example 7. Detailed Implementation

[0018] This invention provides an aging-resistant polysaccharide-based adhesive, comprising β-1,3-glucan, galactomannan, xylan, calcium carbonate, natural polysaccharide additives, and water; the pH value of the aging-resistant polysaccharide-based adhesive is 7-8.5.

[0019] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0020] In this invention, the concentration of β-1,3-glucan in the aging-resistant polysaccharide-based adhesive can be 0.1~40 g / L, or 3~7.5 g / L, specifically 0.1 g / L, 0.5 g / L, 1 g / L, 3 g / L, 4.5 g / L, 5 g / L, 7 g / L, 7.5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, or 40 g / L.

[0021] In this invention, the concentration of galactomannan in the aging-resistant polysaccharide-based adhesive can be 0.1~40 g / L, or 4~8 g / L, specifically 0.1 g / L, 0.5 g / L, 1 g / L, 4 g / L, 4.8 g / L, 5 g / L, 6 g / L, 7 g / L, 7.2 g / L, 7.5 g / L, 8 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, or 40 g / L. In this invention, the galactomannan can include one or more of locust bean gum, tara gum, and fenugreek gum, specifically locust bean gum.

[0022] In this invention, the concentration of xylan in the aging-resistant polysaccharide-based adhesive is 0.1~50 g / L, and can also be 10~40 g / L, specifically 0.1 g / L, 0.5 g / L, 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L or 50 g / L.

[0023] In this invention, the concentration of calcium carbonate in the aging-resistant polysaccharide-based adhesive can be 0.01~2 g / L, or 0.01~0.5 g / L, specifically 0.01 g / L, 0.05 g / L, 0.1 g / L, 0.2 g / L, 0.25 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, 1.2 g / L, 1.5 g / L, 1.8 g / L, or 2 g / L.

[0024] In this invention, the concentration of natural polysaccharide additives in the aging-resistant polysaccharide-based adhesive can be 0.01~25 g / L, or 0.075~20 g / L, specifically 0.01 g / L, 0.05 g / L, 0.075 g / L, 0.1 g / L, 0.375 g / L, 0.5 g / L, 1 g / L, 3 g / L, 5 g / L, 8 g / L, 10 g / L, 11.5 g / L, 12 g / L, 15 g / L, 18 g / L, 20 g / L, 20.75 g / L, 21.05 g / L, or 25 g / L. In this invention, the natural polysaccharide additives may include one or more of pullulan, xanthan gum, and gellan gum, specifically xanthan gum.

[0025] In this invention, the composition of the aging-resistant polysaccharide-based adhesive is as shown in Table 1: Table 1. Composition of aging-resistant polysaccharide-based adhesives (g / L)

[0026] In this invention, the pH value of the aging-resistant polysaccharide-based adhesive is 7-8.5, and can also be 7.2-8.2, or further 7.5-8. According to GB / T 2943-2008 "Adhesive Terminology", the polysaccharide-based adhesive of this invention belongs to natural polymer adhesives and water-borne adhesives.

[0027] The β-1,3-glucan, galactomannan, xylan, and natural polysaccharide auxiliaries used in this invention are all natural polysaccharides derived from plants or microorganisms, exhibiting good biocompatibility. β-1,3-glucan, when dispersed in water, forms a loosely intertwined triple helix structure, which spontaneously aggregates into a dense rod-shaped triple helix after heat treatment, greatly improving the gelling properties of the system. Galactomannan is a polysaccharide with β-1,4-mannan as the main chain and α-1,6-galactose as the side chain, possessing good water solubility and rheological properties, and can interact with xanthan gum to enhance gel strength. Gellan gum exhibits good gelling properties in the presence of calcium ions. This invention, through the synergistic effect of the unique physicochemical properties of polysaccharides from different sources (β-1,3-glucan, galactomannan, xylan, and natural polysaccharide auxiliaries) and the interactions between polysaccharides, produces an aging-resistant polysaccharide-based adhesive with excellent adhesive properties, suitable for repairing fractures in paper artifacts.

[0028] This invention also provides a method for preparing the aging-resistant polysaccharide-based adhesive described in the above technical solution, comprising the following steps: β-1,3-glucan was dissolved in an alkaline solution, the pH was adjusted to 7-8.5, solid and liquid were separated, and the obtained solid component was mixed with water to obtain β-1,3-glucan colloid. Galactomannan, a first inorganic strong base, and water are mixed, subjected to a first heat treatment, and the pH value is adjusted to 7-8.5. Solid-liquid separation is performed, the resulting liquid component is subjected to a first alcohol precipitation, and the resulting first alcohol precipitate is dissolved in water to obtain a galactomannan solution. Xylan, a second inorganic strong base, and water are mixed, subjected to a second heat treatment, and the pH value is adjusted to 7-8.5. Solid-liquid separation is performed, and the resulting liquid component is subjected to a second alcohol precipitation. The resulting second alcohol precipitate is dissolved in water to obtain a xylan solution. The natural polysaccharide auxiliaries, the third inorganic strong base, and water are mixed, subjected to a third heat treatment, and the pH value is adjusted to 7-8.5. The solid and liquid components are separated, and the resulting liquid component is subjected to a third alcohol precipitation. The resulting third alcohol precipitate is dissolved in water to obtain the auxiliary solution. The β-1,3-glucan colloid, galactomannan solution, xylan solution, auxiliary agent solution, calcium carbonate powder and water are mixed and the pH is adjusted to 7-8.5 to obtain the aging-resistant polysaccharide-based adhesive.

[0029] In this invention, β-1,3-glucan is dissolved in an alkaline solution, the pH is adjusted to 7-8.5, solid and liquid are separated, and the resulting solid component is mixed with water to obtain β-1,3-glucan colloid.

[0030] In this invention, the alkaline solution may include one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution and saturated calcium hydroxide aqueous solution; the concentration of the sodium hydroxide solution and potassium hydroxide solution is independently 1~5 mol / L, and may also be 2~4 mol / L, and may further be 3 mol / L.

[0031] In this invention, the dissolution temperature can be room temperature, and the dissolution time can be 2-6 hours, or 3-5 hours, specifically 4 hours; the dissolution can be carried out under stirring conditions.

[0032] In this invention, the acid solution used to adjust the pH value to 7-8.5 includes hydrochloric acid solution and / or acetic acid solution; the concentration of the acid solution can be 1-5 mol / L, or 2-4 mol / L, or even 3 mol / L. In this invention, the pH value can also be 7.2-8.2, or even 7.5-8.

[0033] The present invention does not have any particular limitation on the solid-liquid separation, and any solid-liquid separation method known to those skilled in the art can be used, such as filtration and / or centrifugal separation.

[0034] In this invention, the solid component is washed with water before use. The water used for washing can be deionized water or ultrapure water. The number of times the water is washed can be 2 to 5 times, or even 3 to 4 times.

[0035] In this invention, the mixing may include shear homogenization, wherein the rotation speed of the shear homogenizer may be 8000~30000 r / min, or 10000~20000 r / min, specifically 15000 r / min; the temperature of the shear homogenizer may be 15~30℃, or 20~25℃; and the shear homogenization time may be 2~10 min, or 3~7 min, specifically 5~6 min. In this invention, the water used for mixing may be deionized water or ultrapure water.

[0036] In this invention, the water in the β-1,3-glucan colloid may include deionized water or ultrapure water, and the volume of water in the β-1,3-glucan colloid may account for 5 to 15% of the total volume of water in the aging-resistant polysaccharide-based adhesive, specifically 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%.

[0037] The present invention involves mixing galactomannan, a first inorganic strong base, and water, subjecting it to a first heat treatment, adjusting the pH value to 7-8.5, separating the solid and liquid components, subjecting the resulting liquid component to a first alcohol precipitation, and dissolving the resulting first alcohol precipitate in water to obtain a galactomannan solution.

[0038] In this invention, the first strong base may include one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide, specifically sodium hydroxide. In this invention, the mass ratio of the galactomannan to the first inorganic strong base may be 10-20:1, or 12-18:1, or further 14-15:1, specifically 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1.

[0039] In this invention, the mixing temperature can be room temperature, the mixing time can be 2-6 hours, or 3-5 hours, specifically 4 hours; the mixing can be carried out under stirring conditions.

[0040] In this invention, the temperature of the first heat treatment can be 105~125℃, or 110~120℃, or even 115℃; the time of the first heat treatment can be 5~20 min, or 8~18 min, or even 10~15 min; the first heat treatment can be carried out in a high-pressure steam sterilizer. β-1,3-glucan, when dispersed in water, forms a loosely entangled triple helix structure, which spontaneously aggregates into a dense rod-shaped triple helix after heat treatment, greatly improving the gelling properties of the system.

[0041] After the first heat treatment, the present invention may further cool to room temperature before adjusting the pH value. In the present invention, the cooling may include natural cooling. In the present invention, the acid solution used to adjust the pH value to 7-8.5 includes hydrochloric acid solution and / or acetic acid solution; the concentration of the acid solution may be 1-5 mol / L, or 2-4 mol / L, or further 3 mol / L. In the present invention, the pH value may also be 7.2-8.2, or further 7.5-8.

[0042] The present invention does not have any particular limitation on the solid-liquid separation, and any solid-liquid separation method known to those skilled in the art can be used, such as filtration and / or centrifugal separation.

[0043] In this invention, the first alcohol precipitation may include: mixing the liquid component with an alcohol to perform a first alcohol precipitation. In this invention, the alcohol may include one or more of ethanol, methanol, and propanol, specifically ethanol; the alcohol may be anhydrous alcohol.

[0044] In this invention, the temperature of the first alcohol precipitation can be 2~10℃, or 3~7℃, or even 4~5℃; the volume fraction of alcohol in the first alcohol precipitation process can be 60~90%, or 60~80%, specifically 60%, 65%, 70%, 75%, 80%, 85%, or 90%; the number of first alcohol precipitations can be 2~5 times, or 3~4 times; the time for a single alcohol precipitation can be 1~3 hours, or 1.5~2.5 hours, or even 2 hours.

[0045] In this invention, after alcohol precipitation, the invention may further include solid-liquid separation, wherein the obtained solid component is washed with an alcohol-water solution and then dried to obtain a first alcohol precipitate. This invention does not have a particular limitation on the solid-liquid separation; any solid-liquid separation method well known to those skilled in the art can be used, such as filtration and / or centrifugation. In this invention, the volume fraction of alcohol in the alcohol-water solution can be 60-90%, or 60-80%, specifically 60%, 65%, 70%, 75%, 80%, 85%, or 90%; the alcohol in the alcohol-water solution may include one or more of ethanol, methanol, and propanol. In this invention, the drying temperature can be 70-100°C, or 80-90°C; this invention does not have a particular limitation on the drying time; drying to constant weight is sufficient.

[0046] In this invention, the water in the galactomannan solution may include deionized water or ultrapure water; the volume of water in the galactomannan solution may account for 10-20% of the total volume of water in the aging-resistant polysaccharide-based adhesive, specifically 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%.

[0047] This invention involves mixing xylan, a second inorganic strong base, and water, performing a second heat treatment, adjusting the pH value to 7-8.5, separating the solid and liquid components, subjecting the resulting liquid component to a second alcohol precipitation, and dissolving the resulting second alcohol precipitate in water to obtain a xylan solution.

[0048] In this invention, the second strong base may include one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide, specifically sodium hydroxide. In this invention, the mass ratio of the xylan to the second inorganic strong base may be 10-20:1, or 12-18:1, or further 14-15:1, specifically 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1.

[0049] In this invention, the mixing temperature can be room temperature, the mixing time can be 2-6 hours, or 3-5 hours, specifically 4 hours; the mixing can be carried out under stirring conditions.

[0050] In this invention, the temperature of the second heat treatment can be 105~125℃, 110~120℃, or even 115℃; the time of the second heat treatment can be 5~20min, 8~18min, or even 10~15min; the second heat treatment can be carried out in a high-pressure steam sterilizer.

[0051] After the second heat treatment, the present invention can be further cooled to room temperature before adjusting the pH value. In the present invention, the cooling can include natural cooling. In the present invention, the acid solution used to adjust the pH value to 7-8.5 includes hydrochloric acid solution and / or acetic acid solution; the concentration of the acid solution can be 1-5 mol / L, or 2-4 mol / L, or even 3 mol / L. In the present invention, the pH value can also be 7.2-8.2, or even 7.5-8.

[0052] The present invention does not have any particular limitation on the solid-liquid separation, and any solid-liquid separation method known to those skilled in the art can be used, such as filtration and / or centrifugal separation.

[0053] In this invention, the second alcohol precipitation may include: mixing the liquid component with an alcohol to perform a second alcohol precipitation. In this invention, the alcohol may include one or more of ethanol, methanol, and propanol, specifically ethanol; the alcohol may be anhydrous.

[0054] In this invention, the temperature of the second alcohol precipitation can be 2~10℃, or 3~7℃, or even 4~5℃; the volume fraction of alcohol during the second alcohol precipitation process can be 60~90%, or 60~80%, specifically 60%, 65%, 70%, 75%, 80%, 85%, or 90%; the number of second alcohol precipitations can be 2~5 times, or 3~4 times; the time for a single alcohol precipitation can be 1~3 hours, or 1.5~2.5 hours, or even 2 hours.

[0055] In this invention, after alcohol precipitation, the invention may further include solid-liquid separation, whereby the obtained solid component is washed with an alcohol-water solution and then dried to obtain a second alcohol precipitate. This invention does not specifically limit the solid-liquid separation; any solid-liquid separation method well-known to those skilled in the art can be used, such as filtration and / or centrifugation. In this invention, the volume fraction of alcohol in the alcohol-water solution can be 60-90%, or 60-80%, specifically 60%, 65%, 70%, 75%, 80%, 85%, or 90%; the alcohol in the alcohol-water solution may include one or more of ethanol, methanol, and propanol, specifically ethanol. In this invention, the drying temperature can be 70-100°C, or 80-90°C; this invention does not specifically limit the drying time, drying to constant weight is sufficient.

[0056] In this invention, the water in the xylan solution may include deionized water or ultrapure water; the volume of water in the xylan solution may account for 5-40% of the total volume of water in the aging-resistant polysaccharide-based adhesive, specifically 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%.

[0057] This invention involves mixing a natural polysaccharide auxiliary agent, a third inorganic strong alkali, and water, followed by a third heat treatment to adjust the pH value to 7-8.5, solid-liquid separation, and then subjecting the resulting liquid component to a third alcohol precipitation. The resulting third alcohol precipitate is then dissolved in water to obtain an auxiliary agent solution.

[0058] In this invention, the third strong base may include one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide, specifically sodium hydroxide. In this invention, the mass ratio of the natural polysaccharide auxiliary agent to the third inorganic strong base may be 10-20:1, or 12-18:1, or further 14-15:1, specifically 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1.

[0059] In this invention, the mixing temperature can be room temperature, the mixing time can be 2-6 hours, or 3-5 hours, specifically 4 hours; the mixing can be carried out under stirring conditions.

[0060] In this invention, the temperature of the third heat treatment can be 105~125℃, 110~120℃, or even 115℃; the time of the third heat treatment can be 5~20min, 8~18min, or even 10~15min; the third heat treatment can be carried out in a high-pressure steam sterilizer.

[0061] After the third heat treatment, the present invention may further cool to room temperature before adjusting the pH value. In this invention, the cooling may include natural cooling. In this invention, the acid solution used to adjust the pH value to 7-8.5 includes hydrochloric acid solution and / or acetic acid solution; the concentration of the acid solution may be 1-5 mol / L, or 2-4 mol / L, or even 3 mol / L. In this invention, the pH value may also be 7.2-8.2, or even 7.5-8.

[0062] The present invention does not have any particular limitation on the solid-liquid separation, and any solid-liquid separation method known to those skilled in the art can be used, such as filtration and / or centrifugal separation.

[0063] In this invention, the third alcohol precipitation may include: mixing the liquid component with an alcohol to perform a third alcohol precipitation. In this invention, the alcohol may include one or more of ethanol, methanol, and propanol, specifically ethanol; the alcohol may be anhydrous.

[0064] In this invention, the temperature of the third alcohol precipitation can be 2~10℃, or 3~7℃, or even 4~5℃; the volume fraction of alcohol during the third alcohol precipitation process can be 60~90%, or 60~80%, specifically 60%, 65%, 70%, 75%, 80%, 85%, or 90%; the number of third alcohol precipitations can be 2~5 times, or 3~4 times; the time for a single alcohol precipitation can be 1~3 hours, or 1.5~2.5 hours, or even 2 hours.

[0065] In this invention, after alcohol precipitation, the invention may further include solid-liquid separation, wherein the obtained solid component is washed with an alcohol-water solution and then dried to obtain a third alcohol precipitate. This invention does not have a particular limitation on the solid-liquid separation; any solid-liquid separation method well known to those skilled in the art can be used, such as filtration and / or centrifugation. In this invention, the volume fraction of alcohol in the alcohol-water solution can be 60-90%, or 60-80%, specifically 60%, 65%, 70%, 75%, 80%, 85%, or 90%; the alcohol in the alcohol-water solution may include one or more of ethanol, methanol, and propanol, specifically ethanol. In this invention, the drying temperature can be 70-100℃, or 80-90℃; this invention does not have a particular limitation on the drying time; drying to constant weight is sufficient.

[0066] In this invention, the water in the additive solution may include deionized water or ultrapure water; the volume of water in the additive solution may account for 0.5% to 30% of the total volume of water in the aging-resistant polysaccharide-based adhesive, specifically 0.5%, 2.5%, 5%, 10%, 15%, 20%, 25%, 27% or 30%.

[0067] After obtaining β-1,3-glucan colloid, galactomannan solution, xylan solution and auxiliary agent solution, the present invention mixes the β-1,3-glucan colloid, galactomannan solution, xylan solution, auxiliary agent solution, calcium carbonate powder and water, and adjusts the pH to 7-8.5 to obtain the aging-resistant polysaccharide-based adhesive.

[0068] In this invention, the mixing can be achieved by mixing β-1,3-glucan colloid, galactomannan solution, xylan solution, and auxiliary agent solution, followed by quantitative dilution with water. In this invention, the water can include deionized water or ultrapure water.

[0069] In this invention, the pH adjuster used to adjust the pH to 7-8.5 may include a saturated aqueous solution of calcium hydroxide or a saturated aqueous solution of calcium carbonate.

[0070] In this invention, after adjusting the pH to 7-8.5, the invention may further include shear homogenization to obtain the aging-resistant polysaccharide-based adhesive. In this invention, the rotation speed of the shear homogenizer can be 8000-30000 r / min, or 10000-20000 r / min, or even 15000 r / min; the temperature of the shear homogenizer can be 15-30℃, or even 20-25℃; the shear homogenizer time can be 2-10 min, or 3-7 min, or even 4-5 min.

[0071] This invention also provides the application of the aging-resistant polysaccharide-based adhesive described in the above-described technical solutions, or the aging-resistant polysaccharide-based adhesive prepared by the above-described technical solutions, in the repair of paper tears. The aging-resistant polysaccharide-based adhesive provided by this invention exhibits synergistic effects among its components, demonstrating excellent adhesion to both smooth cuts and tears in paper. Furthermore, the tensile strength after bonding is further increased after accelerated aging treatment, exhibiting excellent aging resistance. In addition, the adhesive also possesses a certain deacidification ability and does not contain organic solvents or synthetic polymers, making it particularly suitable for repairing tears in paper artifacts.

[0072] This invention also provides a method for repairing paper tears, comprising the following steps: laying the paper to be repaired flat on a smooth plate, wetting the paper tear with water, manually piecing the paper together so that the two sides of the tear are neat and without misalignment, applying adhesive to the tear and then letting it dry; the adhesive is any of the aging-resistant polysaccharide-based adhesives described in the above technical solutions or the aging-resistant polysaccharide-based adhesives prepared by the preparation method described in the above technical solutions.

[0073] In this invention, wetting the paper tear with water may include wetting the paper tear with deionized water using a spray method.

[0074] In this invention, the dripping can be performed using a pipette or dropper.

[0075] In this invention, the amount of the aging-resistant polysaccharide-based adhesive used at the crack can be 25~50μL / cm, or 30~45μL / cm, or even 35~40μL / cm.

[0076] In this invention, the drying process can be natural air drying at room temperature. To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of the aging-resistant polysaccharide-based adhesive, its preparation method, and its application, should not be construed as limiting the scope of protection of the present invention.

[0077] In the following examples, β-1,3-glucan (also known as gel polysaccharide, CAS No. 54724-00-4), xylan (CAS No. 9014-63-5), xanthan gum (CAS No. 11138-66-2), locust bean gum (CAS No. 9000-40-2), gellan gum (CAS No. 71010-52-1), and pullulan (CAS No. 9057-02-7) were all purchased from Sinopharm Chemical Reagent Co., Ltd. The product suppliers have no impact on the final effect of the aging-resistant polysaccharide-based adhesive in this invention.

[0078] The selected Xuan paper meets the requirements of GB / T 18739-2008 "Geographical Indication Product Xuan Paper". The Xuan paper samples were collected according to GB / T 450-2008 "Sampling of Paper and Paperboard Samples and Determination of the Longitudinal and Transverse and Front and Back Sides of Samples". The operating conditions were in accordance with GB / T 10739-2023 "Standard Atmospheric Conditions for the Treatment and Testing of Paper, Paperboard and Pulp Samples". The accelerated aging of paper was carried out using GB / T 464-2008 "Dry Heat Accelerated Aging of Paper and Paperboard" (Method C). The tensile strength of paper after tear repair was determined using GB / T 12914-2018 "Determination of Tensile Strength of Paper and Paperboard - Constant Rate Tensile Method (20 mm / min)". The pH of paper was determined using GB / T 1545-2008 "Determination of Acidity or Alkalinity of Water Extracts from Paper, Paperboard and Pulp" (Method B: pH Meter Method).

[0079] Preparation of raw Xuan paper strips with smooth cuts: Select standard raw Xuan paper and determine the transverse and longitudinal directions, as well as the front and back sides, according to GB / T450-2008. Cut the Xuan paper into strips of 200 mm × 50 mm along the longitudinal direction. Cut the strips transversely in an environment of 23±1℃ and 50%±2% relative humidity. Visually inspect the cut surface for smoothness and no burrs, thus obtaining raw Xuan paper strips with smooth cuts.

[0080] Preparation of prepared Xuan paper strips with smooth cuts: Select prepared Xuan paper that meets the standards and determine the transverse and longitudinal directions, as well as the front and back sides of the Xuan paper, according to GB / T 450-2008. Cut the Xuan paper into strips of 200 mm × 50 mm along the longitudinal direction. Cut the strips transversely in an environment of 23±1℃ and 50%±2% relative humidity. Visually inspect the cut surface for smoothness and no burrs, thus forming a prepared Xuan paper strip with a smooth cut.

[0081] Preparation of raw Xuan paper strips with frayed edges: Fold a complete 200 mm × 50 mm strip of Xuan paper along its long side to form a crease, then tear it along the crease to form raw Xuan paper strips with frayed edges. The presence of frayed edges is a clearly defined requirement in the restoration of ancient books (GB / T 21712-2008 Technical Specifications and Quality Requirements for Ancient Book Restoration).

[0082] Example 1 Pretreatment of β-1,3-glucan: 10.0 g of β-1,3-glucan was added to 1 L of 0.1 mol / L NaOH solution and stirred at room temperature for 4 h until the solution was clear and transparent. The pH was adjusted to 8.0 with 2 mol / L acetic acid solution, and stirring was continued for 2 h. The mixture was centrifuged at 5000 g for 30 min, and the supernatant was discarded. 500 mL of deionized water was added to the precipitate and stirred until homogeneous. The mixture was then centrifuged at 5000 g for 30 min, the supernatant was discarded, and 500 mL of deionized water was added back to the precipitate. This operation was repeated 3 times, and the precipitate was recovered by centrifugation. The volume was adjusted to 200 mL with deionized water, and the mixture was homogenized by high-speed shearing at 15000 r / min for 5 min to obtain a β-1,3-glucan colloid with a concentration of 50 g / L. The protein content in the β-1,3-glucan colloid was determined to be 1.8% of the polysaccharide mass using the Coomassie Brilliant Blue method. The colloid was stored at 4℃ for later use.

[0083] Pretreatment of Sophora japonica gum: 10.0 g of Sophora japonica gum and 0.5 g of sodium hydroxide granules were added to 1 L of deionized water and stirred at room temperature for 4 h until completely dissolved. The solution was placed in an autoclave and treated at 105 °C for 15 min. After naturally cooling to room temperature, the pH was adjusted to 7.5 with 2 mol / L hydrochloric acid, and then centrifuged at 5000 g for 30 min to recover the supernatant. 4 L of anhydrous ethanol was added to the supernatant, and the mixture was allowed to stand at 4 °C for 12 h, followed by centrifugation at 5000 g for 30 min to recover the precipitate. The precipitate was washed three times with 75% ethanol and then dried in an oven at 80 °C to constant weight to obtain 8.0 g of polysaccharide. The polysaccharide was dissolved in 200 mL of deionized water, and the pH was adjusted to 8.5 with saturated calcium hydroxide solution to obtain a Sophora japonica gum solution with a concentration of 40 g / L. The mass of protein in the solution was determined to be 1.7% of the polysaccharide mass using the Coomassie brilliant blue method. The solution was stored at 4 °C for later use.

[0084] Xylan, xanthan gum, pullulan, and gellan gum were pretreated according to the pretreatment method for locust bean gum, respectively, to prepare xylan solutions with a concentration of 100 g / L, xanthan gum solutions with a concentration of 15 g / L, pullulan solutions with a concentration of 100 g / L, and gellan gum solutions with a concentration of 15 g / L, respectively. The proportion of protein to polysaccharide in all four solutions was less than 2% as determined by the Coomassie brilliant blue method. All solutions were stored at 4℃ for later use.

[0085] According to Table 2, β-1,3-glucan colloid, locust bean gum solution, xylan solution, xanthan gum solution, pullulan polysaccharide solution, gellan gum solution and calcium carbonate powder were added, quantitatively diluted with deionized water, and the pH value was adjusted with saturated calcium hydroxide aqueous solution. After high-speed homogenization at 15000 r / min for 5 min, the aging-resistant polysaccharide-based adhesive (numbered 1#) was obtained.

[0086] Examples 2-10 The aging-resistant polysaccharide-based adhesive was prepared according to the method of Example 1. The only difference from Example 1 is that the composition of the aging-resistant polysaccharide-based adhesive is shown in Table 2, and the aging-resistant polysaccharide-based adhesives prepared in Examples 2 to 10 are numbered 2# to 10# respectively.

[0087] Comparative Example 1 The aging-resistant polysaccharide-based adhesive was prepared according to the method of Example 1. The only difference from Example 1 is that the composition of the aging-resistant polysaccharide-based adhesive is shown in Table 2, and the aging-resistant polysaccharide-based adhesive prepared in Comparative Example 1 is numbered 11#.

[0088] Table 2. Composition of the aging-resistant polysaccharide-based adhesives in Examples 1-10 and Comparative Example 1

[0089] Comparative Example 2 According to the method in Example 1, locust bean gum, xanthan gum, and pullulan polysaccharide were pretreated separately. The resulting locust bean gum solution, xanthan gum solution, and pullulan polysaccharide solution were mixed and quantitatively diluted with deionized water to obtain a polysaccharide mixed solution gel (denoted as 12#). The mass ratio of locust bean gum, xanthan gum, and pullulan polysaccharide in the polysaccharide mixed solution gel was 4:5:1, and the total concentration of the three was 15 g / L.

[0090] Comparative Example 3 Sophora japonica gum, xanthan gum, and pullulan were pretreated according to the method in Example 1. The resulting solutions of sophora japonica gum, xanthan gum, and pullulan were mixed and quantitatively diluted with deionized water to obtain a polysaccharide mixture gel (denoted as 13#). The mass ratio of sophora japonica gum, xanthan gum, and pullulan was 4:5:1, and the total concentration of the three was 10 g / L.

[0091] Test Example 1 The impact of accelerated aging treatment on the smooth incision repair of raw Xuan paper. A strip of raw Xuan paper with a smooth cut was placed face up on a smooth flat surface and moistened with deionized water spray. The broken edges were then manually joined together, avoiding overlapping of the paper strips on both sides at the break. To illustrate the adhesive's bonding effect, misalignment of the paper strips along the break direction was allowed. Adhesive #3 was evenly applied to the break at a rate of 25 μL / cm of the cut, allowing the adhesive to spread laterally by approximately 6 mm, meeting the width requirements (4~10 mm) for tear bonding using thin paper as specified in GB / T 42468.3-2023 "Specifications for the Rescue and Restoration of Paper Archives Part 3: Restoration Quality Requirements". The paper strips were then allowed to air dry naturally under laboratory conditions to form a repaired break, serving as a normal sample. A portion of the repaired paper strips was subjected to accelerated aging at 105℃ for 72 hours according to GB / T 464-2008, serving as an accelerated aging sample. Both the normal sample and the accelerated aging sample showed a transparent film forming in the adhesive-repaired area, with no color difference from the main paper strip. The tensile strength of normal samples and accelerated aging samples was determined by constant-rate tensile testing, and the results are shown in Table 3.

[0092] Table 3 Tensile strength of samples after repair of smooth cuts on raw Xuan paper with adhesive #3 (mean ± standard deviation)

[0093] Table 3 shows that the adhesive effectively achieves bonding of smooth cuts. After accelerated dry heat aging, the tensile strength of the cut was significantly improved. This result is related to the characteristics of the polysaccharides used in the adhesive. Thermal gelation upon heating is a typical characteristic; galactomannan and xanthan gum exhibit a synergistic effect, significantly increasing gel strength upon heating. The accelerated aging process enhances the gel strength of the polysaccharides in the adhesive, thus increasing the tensile strength. The results indicate that the adhesive possesses a certain degree of anti-aging ability.

[0094] Additionally, create paper strips with irregular tears to demonstrate the bonding effect. Figure 1 The figure shows the bonding effect of adhesive #3 on a smooth cut with irregular breaks (where A represents the bonding effect and B represents the film transparency). As can be seen from the figure, in addition to effectively bonding smooth cuts, the adhesive can also form a highly transparent film at irregular breaks, further demonstrating the adhesive's ability to repair irregular breaks.

[0095] Test Example 2 Comparison of the effects of adhesives on the repair of smooth cuts and tears in raw Xuan paper. Two types of raw Xuan paper strips, one with a smooth cut and the other with a torn section containing paper fiber stubble, were placed face up on a smooth flat surface. They were moistened with deionized water spray and manually joined together at the torn section, avoiding overlapping. To illustrate the adhesive's bonding effect, misalignment of the paper strips along the tear direction was allowed. Adhesive #1 was evenly applied to the tear at a rate of 25 μL / cm of cut. The strips were allowed to air dry under laboratory conditions to repair the tear. The repaired paper strips were then subjected to dry heat treatment at 105℃ for 72 h to accelerate aging, according to GB / T 464-2008. The tensile strength of the smooth-cut and torn samples was determined using the constant-rate tensile test, and the results are shown in Table 4.

[0096] Table 4. Tensile strength of raw Xuan paper repaired with #1 adhesive after accelerated aging treatment (mean ± standard deviation)

[0097] As shown in Table 4, compared with the smooth cut, the presence of burrs at the tear joint leads to cross-linking between the fibers on both sides of the tear, significantly improving the adhesive effect. After accelerated dry heat aging, the tensile strength of the tear joint is significantly higher than that of the smooth cut, with a folded fracture length of 1.68 ± 0.23 km, close to the national standard requirement for cotton-based Xuan paper (1.70 km). The results indicate that the presence of paper fiber burrs at the fracture joint can greatly enhance the repair effect of the adhesive.

[0098] Test Example 3 Comparison of the effects of adhesives on the repair of raw and processed Xuan paper. Adhesive #3 was applied evenly at a rate of 40 μL / cm to the fracture surfaces of both raw and processed Xuan paper strips with smooth cuts. The strips were then allowed to air dry under laboratory conditions to repair the fractures. The repaired paper strips were then subjected to dry heat treatment at 105℃ for 72 h to accelerate aging, as required by GB / T 464-2008. The tensile strength of the smooth cut surfaces of both raw and processed Xuan paper was determined using the constant-rate tensile test, and the results are shown in Table 5.

[0099] Table 5. Tensile strength of raw and sized Xuan paper after accelerated aging treatment with #3 adhesive (mean ± standard deviation)

[0100] As shown in Table 5, the adhesive has a stronger bonding effect on sized Xuan paper compared to raw Xuan paper. This result indicates that the gelatin on the surface of sized Xuan paper partially dissolves during the treatment process and interacts with the polysaccharide component of the adhesive. Further accelerated aging treatment can significantly improve the bonding strength.

[0101] Test Example 4 Comparison of adhesive component ratios and their effects on smooth incision repair using raw Xuan paper. Adhesives #1 to #4 were evenly applied at a rate of 30 μL / cm to the torn edges of smooth-cut raw Xuan paper strips. The strips were then allowed to air dry under laboratory conditions to repair the tears. The repaired paper strips were then subjected to a dry heat treatment at 105℃ for 72 h to accelerate aging, according to GB / T 464-2008. The tensile strength of the smooth-cut edges of the raw Xuan paper strips was determined using the constant-rate tensile test. Figure 2 The tensile strength (mean ± standard deviation) of adhesives 1# to 4# after accelerated aging treatment of smooth cuts on raw Xuan paper has been measured. The test results show that the adhesive strength on smooth cuts on raw Xuan paper gradually increases with increasing polysaccharide content. Adhesive 4# achieves an effective bonding strength on smooth cuts equivalent to a breaking length of 1.28 ± 0.15 km, demonstrating excellent performance.

[0102] Test Example 5 The effect of calcium carbonate on the repair of raw Xuan paper strips with smooth cuts. Adhesives #2 and #8 through #10 were evenly applied at a rate of 25 μL / cm to the fractured edges of smooth-cut raw Xuan paper strips. The strips were then allowed to air dry under laboratory conditions to repair the fractures. The repaired paper strips were then subjected to dry heat treatment at 105℃ for 72 h to accelerate aging, as required by GB / T 464-2008. The tensile strength of the smooth-cut edges of the raw Xuan paper strips was determined using the constant-rate tensile test. Figure 3 The tensile strength (mean ± standard deviation) of the repaired smooth cut surface of raw Xuan paper after accelerated aging treatment was measured based on the calcium carbonate content in the adhesive (adhesives #2 and #8~#10). The test results show that the adhesive strength to the smooth cut surface of the raw Xuan paper gradually increases with increasing calcium carbonate content, which is largely related to the role of calcium ions in promoting polysaccharide gelation. When the calcium carbonate concentration reaches 0.5 g / L, the average tensile strength reaches 2.85 times the initial value. With increasing calcium carbonate concentration, the repaired fracture area gradually turns whiter, creating a color difference with the original paper. Therefore, a concentration of less than 0.5 g / L is preferred.

[0103] Test Example 6 Scanning electron microscopy imaging of smooth incisions repaired with adhesives (2#, 4#, 12#) from raw Xuan paper. Adhesives #2, #4, and #12 were selected and applied evenly at a rate of 25 μL / cm to the fractured edges of raw Xuan paper strips with smooth cuts. The strips were then allowed to air dry under laboratory conditions to repair the fracture. The repaired paper strips were then used for scanning electron microscopy imaging of the fractured area.

[0104] Figure 4 and Figure 5Scanning electron microscopy (SEM) images of the fracture surfaces after repairing smooth cuts in raw Xuan paper using adhesives #2 and #4, respectively. The results show that the smooth cut treatment caused fiber misalignment on both sides of the fracture, preventing proper alignment. Both adhesives, however, effectively bonded the fracture surface without relying on fiber entanglement. After repair, the adhesives not only filled the fracture but also formed a thin film on the fiber surfaces near the fracture, reinforcing the structure. Adhesive #4, with its higher polysaccharide content, formed a more uniform film, consistent with its higher tensile strength.

[0105] Figure 6 The image shows a scanning electron microscope (SEM) image of the fractured area after repairing a smooth cut on raw Xuan paper with adhesive #12. It is evident that the smooth cut treatment caused fiber misalignment on both sides of the fracture, preventing proper alignment. Furthermore, the mixture of locust bean gum and xanthan gum failed to effectively bond the fractured area. Although a film formed on the paper surface by the mixture was observed after repair, the fracture remained. This result is significantly different from the repair effect of the adhesive described in Example 6, indicating that the aging-resistant polysaccharide-based adhesive prepared in this invention has a better repair effect on paper fractures than the natural polysaccharide mixture (#12).

[0106] Test Example 7 Adhesives #4 and #13 were selected and applied evenly at a rate of 25 μL / cm to the fractured edges of a strip of raw Xuan paper with a smooth cut. The strips were then allowed to air dry under laboratory conditions to repair the fracture. The tensile strength of the paper was then measured using a universal tensile testing machine. The curve showing the change in tensile strength with paper deformation is shown below. Figure 7 As shown, the results indicate that the adhesive prepared in this invention has a maximum tensile strength more than twice that of the polysaccharide mixture, and the paper exhibits stronger resistance to deformation. The results demonstrate that the aging-resistant polysaccharide-based adhesive of this invention provides better repair of paper tears than the natural polysaccharide mixture.

[0107] Test Example 8 The effect of adhesives on the pH of newspapers Newly published newspapers and old newspapers showing obvious signs of aging and browning (newspapers from 2000) were selected and cut into 20 cm × 20 cm samples. Adhesives #5~#7 and #11 were applied at a concentration of 50 μL / cm³. 2 The adhesive was evenly sprayed onto the surface of the newspaper sample and allowed to air dry under laboratory conditions. Using the sample without adhesive as a control, the pH value of the aqueous extract of the sample was determined according to GB / T 1545-2008. The results are shown in Table 6.

[0108] Table 6. Effect of adhesives on the pH value of newspapers (average)

[0109] As shown in Table 6, the adhesive provided by this invention can significantly increase the pH value of newspapers and exhibits a certain deacidification ability for acidified paper, which meets the requirements for the restoration of paper cultural relics. The addition of natural polysaccharide additives increases the pH value of the paper.

[0110] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An aging-resistant polysaccharide-based adhesive, characterized in that, It includes β-1,3-glucan, galactomannan, xylan, calcium carbonate, natural polysaccharide additives, and water; The pH value of the aging-resistant polysaccharide-based adhesive is 7~8.

5.

2. The aging-resistant polysaccharide-based adhesive according to claim 1, characterized in that, In the aging-resistant polysaccharide-based adhesive, the concentration of β-1,3-glucan is 0.1~40 g / L, the concentration of galactomannan is 0.1~40 g / L, the concentration of xylan is 0.1~50 g / L, the concentration of calcium carbonate is 0.01~2 g / L, and the concentration of natural polysaccharide auxiliaries is 0.01~25 g / L.

3. The aging-resistant polysaccharide-based adhesive according to claim 1 or 2, characterized in that, The galactomannan includes one or more of locust bean gum, tara gum, and fenugreek gum.

4. The aging-resistant polysaccharide-based adhesive according to claim 1 or 2, characterized in that, The natural polysaccharide additives include one or more of pullulan, xanthan gum, and gellan gum.

5. The method for preparing the aging-resistant polysaccharide-based adhesive according to any one of claims 1 to 4, characterized in that, Includes the following steps: β-1,3-glucan was dissolved in an alkaline solution, the pH was adjusted to 7-8.5, solid and liquid were separated, and the obtained solid component was mixed with water to obtain β-1,3-glucan colloid. Galactomannan, a first inorganic strong base, and water are mixed, subjected to a first heat treatment, and the pH value is adjusted to 7-8.

5. Solid-liquid separation is performed, the resulting liquid component is subjected to a first alcohol precipitation, and the resulting first alcohol precipitate is dissolved in water to obtain a galactomannan solution. Xylan, a second inorganic strong base, and water are mixed, subjected to a second heat treatment, and the pH value is adjusted to 7-8.

5. Solid-liquid separation is performed, and the resulting liquid component is subjected to a second alcohol precipitation. The resulting second alcohol precipitate is dissolved in water to obtain a xylan solution. The natural polysaccharide auxiliaries, the third inorganic strong base, and water are mixed, subjected to a third heat treatment, and the pH value is adjusted to 7-8.

5. The solid and liquid components are separated, and the resulting liquid component is subjected to a third alcohol precipitation. The resulting third alcohol precipitate is dissolved in water to obtain the auxiliary solution. The β-1,3-glucan colloid, galactomannan solution, xylan solution, auxiliary agent solution, calcium carbonate powder and water are mixed and the pH is adjusted to 7-8.5 to obtain the aging-resistant polysaccharide-based adhesive.

6. The preparation method according to claim 5, characterized in that, The alkaline solution includes one or more of sodium hydroxide solution, potassium hydroxide solution, and saturated calcium hydroxide solution.

7. The preparation method according to claim 5, characterized in that, The first strong base, the second strong base, and the third strong base independently include one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide; The mass ratio of the galactomannan to the first inorganic strong base is 10~20:1; The mass ratio of the xylan to the second inorganic strong base is 10~20:1; The mass ratio of the natural polysaccharide auxiliary agent to the third inorganic strong base is 10~20:1; The temperatures for the first, second, and third heat treatments are independently 105~125℃, and the times are independently 5~20min; The alcohols used for the first, second, and third alcohol precipitations independently include one or more of ethanol, methanol, and propanol; In the first, second, and third alcohol precipitation processes, the volume fraction of alcohol is 60-90%, the single alcohol precipitation time is 1-3 hours, and the number of alcohol precipitations is 2-5 times independently.

8. The application of the aging-resistant polysaccharide-based adhesive according to any one of claims 1 to 4 or the aging-resistant polysaccharide-based adhesive prepared by the preparation method according to any one of claims 5 to 7 in the repair of paper tears.

9. A method for repairing a torn section of paper, comprising the following steps: Lay the paper to be repaired flat on a smooth plate, moisten the torn edge with water, and manually splice the paper on both sides of the torn edge so that they are neat and without misalignment. Apply adhesive to the crack and let it dry. The adhesive is the aging-resistant polysaccharide-based adhesive according to any one of claims 1 to 4 or the aging-resistant polysaccharide-based adhesive prepared by the preparation method according to any one of claims 5 to 7.

10. The repair method according to claim 9, characterized in that, The amount of adhesive used at the crack is 25~50 μL / cm.

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