A fire-retardant adhesive with high adhesive strength, its preparation method and application

Abstract

The present application belongs to the technical field of adhesive, and particularly relates to an adhesive with fire resistance and high adhesive strength, and a preparation method and application thereof. The modified cationic starch is used as a base material to prepare the adhesive. The modified cationic starch can improve the solid content of the adhesive, and further improve the adhesive strength. Compared with adding single magnesium hydroxide or zinc borate, adding the magnesium hydroxide and zinc borate composite flame retardant to the modified cationic starch can not only improve the adhesive strength and water resistance of the adhesive, but also significantly enhance the flame retardance of the adhesive, effectively solve the problems in the prior art, and be more suitable for the production of file holders. The file holder prepared by using the adhesive can realize firmer adhesion, maintain the structural stability of the file holder, and provide more durable and safe and stable protection for the files in the box.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to an adhesive that combines flame retardancy and high adhesive strength, its preparation method, and its application. Background Technology

[0002] Starch, when gelatinized with water upon heating, forms a colloid with a certain degree of viscosity, making it a widely available and environmentally friendly natural adhesive. However, due to its inherent molecular structure, ordinary starch adhesives generally suffer from drawbacks such as low bonding strength, poor water resistance, and slow drying speed. If used directly in the production of file boxes, they cannot meet the stringent requirements for long-term preservation and storage. Therefore, chemical modification methods are commonly used to treat starch, with cationic starch becoming a research hotspot due to its positive charge and good affinity with fiber and other substrates.

[0003] In existing technologies, cationic starch is mainly prepared by introducing cationic groups into starch molecules through reactions such as etherification, esterification, or graft copolymerization. However, the above modification methods still have many shortcomings. On the one hand, the cationic starch adhesives modified by conventional methods such as oxidation and etherification, as described in patent CN1982395A, still have unsatisfactory adhesive strength and moisture resistance. On the other hand, adhesives prepared with cationic starch as a base material generally suffer from drawbacks such as easy delamination and low solid content, resulting in poor storage stability and limiting their industrial application.

[0004] Furthermore, for archival equipment, adhesives are required not only to have high bonding strength but also flame-retardant properties to provide long-lasting protection for the documents inside. Magnesium hydroxide and zinc borate, as non-toxic, environmentally friendly, and thermally stable flame retardants, have been widely used in various industries such as wood, rubber, plastics, papermaking, and fiber. In the papermaking industry, magnesium hydroxide and zinc borate are often added directly to pulp or coated onto the paper surface. However, directly adding flame retardants through physical blending to cationic starch adhesives presents problems such as uneven dispersion of the flame retardants, poor compatibility with the starch matrix, low flame-retardant efficacy, and large addition amounts. This not only affects the adhesive performance but also makes it difficult to simultaneously meet the dual requirements of flame retardancy and high-strength bonding.

[0005] Therefore, it is urgent to modify cationic starch so that it can have good flame retardant properties when flame retardants are added, as well as high bonding strength, good storage stability and suitable solid content under normal use conditions. Summary of the Invention

[0006] This invention provides an adhesive that combines flame retardancy and high bonding strength, along with its preparation method and application. Modified cationic starch increases the solid content of the adhesive, thereby improving its bonding strength. Furthermore, the addition of a magnesium hydroxide and zinc borate composite flame retardant to the modified cationic starch imparts flame retardancy and water resistance to the treated archival equipment, effectively solving the problems existing in the prior art and making it more suitable for the production of archival equipment. The specific technical solution of this invention is as follows: An adhesive that combines flame retardancy and high bonding strength is characterized in that the adhesive is made of polyvinyl alcohol-modified cationic starch and a flame retardant slurry. The mass ratio of polyvinyl alcohol to cationic starch is 0.6~1:1; The mass ratio of the flame retardant slurry to cationic starch is 1.7~2:1.

[0007] Furthermore, a method for preparing an adhesive that combines flame retardancy and high adhesive strength is characterized by comprising the following steps: S1. Prepare a polyvinyl alcohol solution; S2. Add cationic starch to polyvinyl alcohol solution to obtain modified cationic starch solution; S3. Mix nano-magnesium hydroxide and nano-zinc borate, and ultrasonically treat to prepare flame retardant slurry; S4. Add the flame retardant slurry to the modified cationic starch solution.

[0008] Furthermore, a method for preparing an adhesive that combines flame retardancy and high bonding strength is characterized in that, in step S1, polyvinyl alcohol is added to ultrapure water to obtain a polyvinyl alcohol solution with a mass fraction of 2% to 2.2%, and the solution is magnetically stirred for 25 to 30 minutes at a constant temperature of 90 to 95°C and a rotation speed of 70 to 100 r / min to completely dissolve the polyvinyl alcohol.

[0009] Furthermore, a method for preparing an adhesive that combines flame retardancy and high bonding strength is characterized in that, in step S2, the adhesive is magnetically stirred for 20-30 minutes at a temperature of 95-100℃ and a rotation speed of 70-100 r / min to completely gelatinize the cationic starch.

[0010] Furthermore, a method for preparing an adhesive that combines flame retardancy and high bonding strength is characterized in that, in step S3, a mixture of nano-magnesium hydroxide and nano-zinc borate is dissolved in ultrapure water and treated for 10-15 minutes under ultrasonic power of 700-800W, ultrasonic frequency of 40-50kHz, and ultrasonic temperature of 50-60℃ to ensure uniform dispersion of nano-magnesium hydroxide and nano-zinc borate.

[0011] Furthermore, the mass ratio of nano-magnesium hydroxide to nano-zinc borate in S3 is 2.5~3:1.

[0012] Furthermore, a method for preparing an adhesive that combines flame retardancy and high bonding strength is characterized in that, in step S4, the flame retardant slurry and the modified cationic starch solution are magnetically stirred for 5 to 10 minutes at a temperature of 90 to 95°C and a rotation speed of 70 to 100 r / min to ensure uniform mixing.

[0013] Furthermore, the adhesive prepared according to the above-mentioned method for preparing an adhesive that combines flame retardancy and high adhesive strength is applied in archival equipment.

[0014] Furthermore, a method for applying an adhesive that combines flame retardancy and high bonding strength in archival equipment is characterized in that the adhesive is applied to the archival equipment by brushing or dotting.

[0015] Furthermore, a method for applying an adhesive that combines flame retardancy and high bonding strength in archival equipment is characterized in that the adhesive layer thickness is 0.15~0.2mm, and the curing temperature of the brushing or dispensing method is 25~28℃.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses modified cationic starch as a base material to prepare an adhesive. Starch is a polysaccharide, and its basic building block is glucose. Each glucose ring has three free hydroxyl groups (-OH). These free hydroxyl groups easily combine to form hydrogen bonds. These hydrogen bonds attract each other, forming larger aggregates that eventually settle. Polyvinyl alcohol also has many hydroxyl groups, forming more stable intermolecular hydrogen bonds with the hydroxyl groups of starch, effectively "holding" the starch molecules together and reducing aggregation. This allows the adhesive to maintain a uniform and stable state for a longer period. Using the modified cationic starch of this invention improves the adhesive strength of the adhesive.

[0017] 2. The modified cationic starch used in this invention can increase the solid content of the adhesive, thereby improving the adhesive strength.

[0018] 3. By adding magnesium hydroxide and zinc borate in combination, this invention not only synergistically improves the adhesive strength and water resistance of the adhesive compared to adding magnesium hydroxide or zinc borate alone, but also significantly enhances the flame retardancy of the adhesive. Archives made using the adhesive of this invention can achieve a stronger bond, maintain the structural stability of the archives, and provide more durable and safe protection for the archives inside the box. Attached Figure Description

[0019] Figure 1 The bonding strength of samples after treatment under different conditions; Figure 2Combustion performance of samples treated under different conditions: (a) afterflame time, (b) ignition time, and (c) char length; Figure 3 Thermogravimetric curves of samples treated under different conditions; Detailed Implementation The technical solution of the present invention will be further illustrated below through embodiments, experiments and accompanying drawings.

[0020] Example 1 An adhesive that combines flame retardancy and high bonding strength is disclosed. The adhesive is made from polyvinyl alcohol-modified cationic starch with added flame retardant slurry. The mass ratio of polyvinyl alcohol to cationic starch is 0.66:1. The mass ratio of the flame retardant slurry to cationic starch is 1.77:1. A method for preparing an adhesive that combines flame retardancy and high adhesive strength includes the following steps: S1. Prepare a polyvinyl alcohol solution; S2. Add cationic starch to polyvinyl alcohol solution to obtain modified cationic starch solution; S3. Mix nano-magnesium hydroxide and nano-zinc borate, and ultrasonically treat to prepare flame retardant slurry; S4. Add the flame retardant slurry to the modified cationic starch solution.

[0021] Polyvinyl alcohol was added to ultrapure water in S1 to obtain a 2% polyvinyl alcohol solution. The solution was then magnetically stirred for 30 minutes at a constant temperature of 90°C and a rotation speed of 100 r / min to completely dissolve the polyvinyl alcohol.

[0022] In S2, the cationic starch was completely gelatinized by magnetic stirring for 20 minutes at a temperature of 95℃ and a rotation speed of 100r / min.

[0023] In step S3, a mixture of nano-magnesium hydroxide and nano-zinc borate was dissolved in ultrapure water and treated for 10 minutes under ultrasonic conditions of 800W, 50kHz, and 50℃ to ensure uniform dispersion of the nano-magnesium hydroxide and nano-zinc borate. The mass ratio of nano-magnesium hydroxide to nano-zinc borate was 3:1.

[0024] In S4, under conditions of 90℃ and 100r / min, magnetic stirring is performed for 5 minutes to ensure uniform mixing of the flame retardant slurry and the modified cationic starch solution.

[0025] The adhesive prepared by the above-mentioned method, which combines flame retardancy and high bonding strength, is used in archival equipment.

[0026] A method for applying an adhesive with both flame retardancy and high bonding strength to archival equipment, wherein the adhesive is applied to the archival equipment by brushing or dispensing, the adhesive layer thickness is 0.15 mm, and the curing temperature of the brushing or dispensing method is 28°C.

[0027] Example 2 An adhesive that combines flame retardancy and high bonding strength is disclosed. The adhesive is made from polyvinyl alcohol-modified cationic starch with added flame retardant slurry. The mass ratio of polyvinyl alcohol to cationic starch is 0.6:1. The mass ratio of the flame retardant slurry to cationic starch is 1.7:1. A method for preparing an adhesive that combines flame retardancy and high adhesive strength includes the following steps: S1. Prepare a polyvinyl alcohol solution; S2. Add cationic starch to polyvinyl alcohol solution to obtain modified cationic starch solution; S3. Mix nano-magnesium hydroxide and nano-zinc borate, and ultrasonically treat to prepare flame retardant slurry; S4. Add the flame retardant slurry to the modified cationic starch solution.

[0028] Polyvinyl alcohol was added to ultrapure water in S1 to obtain a polyvinyl alcohol solution with a mass fraction of 2.1%. The solution was then magnetically stirred for 30 minutes at a constant temperature of 95°C and a rotation speed of 85 r / min to completely dissolve the polyvinyl alcohol.

[0029] In S2, the cationic starch is magnetically stirred for 30 minutes at a temperature of 95℃ and a rotation speed of 85r / min to completely gelatinize it.

[0030] In S3, a mixture of nano-magnesium hydroxide and nano-zinc borate was dissolved in ultrapure water and treated for 15 minutes under ultrasonic power of 750W, ultrasonic frequency of 40kHz, and ultrasonic temperature of 55℃ to ensure uniform dispersion of the nano-magnesium hydroxide and nano-zinc borate. The mass ratio of nano-magnesium hydroxide to nano-zinc borate was 2.5:1.

[0031] In S4, under conditions of 95℃ and 85r / min, magnetic stirring is performed for 5 minutes to ensure uniform mixing of the flame retardant slurry and the modified cationic starch solution.

[0032] The adhesive prepared by the above-mentioned method, which combines flame retardancy and high bonding strength, is used in archival equipment.

[0033] A method for applying an adhesive with both flame retardancy and high bonding strength to archival equipment, wherein the adhesive is applied to the archival equipment by brushing or dispensing, the adhesive layer thickness is 0.15 mm, and the curing temperature of the brushing or dispensing method is 25°C.

[0034] Example 3 An adhesive that combines flame retardancy and high bonding strength is disclosed. The adhesive is made from polyvinyl alcohol-modified cationic starch with added flame retardant slurry. The mass ratio of polyvinyl alcohol to cationic starch is 1:1. The flame retardant slurry has a mass ratio of 2:1 to cationic starch. A method for preparing an adhesive that combines flame retardancy and high adhesive strength includes the following steps: S1. Prepare a polyvinyl alcohol solution; S2. Add cationic starch to polyvinyl alcohol solution to obtain modified cationic starch solution; S3. Mix nano-magnesium hydroxide and nano-zinc borate, and ultrasonically treat to prepare flame retardant slurry; S4. Add the flame retardant slurry to the modified cationic starch solution.

[0035] Polyvinyl alcohol was added to ultrapure water in S1 to obtain a polyvinyl alcohol solution with a mass fraction of 2.2%. The solution was then magnetically stirred for 25 minutes at a constant temperature of 95°C and a rotation speed of 70 r / min to completely dissolve the polyvinyl alcohol.

[0036] In S2, the cationic starch is magnetically stirred for 30 minutes at a temperature of 100℃ and a rotation speed of 70r / min to completely gelatinize it.

[0037] In S3, a mixture of nano-magnesium hydroxide and nano-zinc borate was dissolved in ultrapure water and treated for 10 minutes under ultrasonic power of 700W, ultrasonic frequency of 50kHz, and ultrasonic temperature of 60℃ to ensure uniform dispersion of the nano-magnesium hydroxide and nano-zinc borate. The mass ratio of nano-magnesium hydroxide to nano-zinc borate was 3:1.

[0038] In S4, the flame retardant slurry and modified cationic starch solution are mixed evenly under the conditions of 95℃ and 70r / min by magnetic stirring for 10min.

[0039] The adhesive prepared by the above-mentioned method, which combines flame retardancy and high bonding strength, is used in archival equipment.

[0040] A method for applying an adhesive with both flame retardancy and high bonding strength to archival equipment, wherein the adhesive is applied to the archival equipment by brushing or dispensing, the adhesive layer thickness is 0.2 mm, and the curing temperature of the brushing or dispensing method is 28°C.

[0041] The adhesive prepared in Example 1 was used in the following experiments A, B, C, and D to verify the effectiveness of the technical solution of the present invention. The adhesives prepared in Examples 2-3 also have similar technical effects.

[0042] It should be noted that the technical terms used in the experimental section have the following meanings: Blank samples refer to samples without any added flame retardants, i.e., only modified cationic starch samples. The specific preparation method involves adding polyvinyl alcohol (PVA) to ultrapure water to obtain a 2% (w / w) PVA solution. This solution is then magnetically stirred at 90°C and 100 rpm for 30 minutes to completely dissolve the PVA. Next, the solution is magnetically stirred at 95°C and 100 rpm for 20 minutes to completely gelatinize the cationic starch. The mass ratio of PVA to cationic starch is 0.66:1.

[0043] The adhesives with added single flame retardant materials refer to adhesives with added single zinc borate and adhesives with added single magnesium hydroxide. Among them, (1) the specific preparation method of the adhesive with added single zinc borate is to first add polyvinyl alcohol to ultrapure water to obtain a polyvinyl alcohol solution with a mass fraction of 2%, and then magnetically stir for 30 minutes at a constant temperature of 90℃ and a rotation speed of 100r / min to completely dissolve the polyvinyl alcohol. Then, cationic starch is added to the polyvinyl alcohol solution to make the mass ratio of polyvinyl alcohol to cationic starch 0.66:1. At a temperature of 95℃ and a rotation speed of 100r / min, the mixture is magnetically stirred for 20 minutes to completely gelatinize the cationic starch and obtain a modified cationic starch solution. Then, nano zinc borate is dissolved in ultrapure water and treated for 10 minutes at an ultrasonic power of 800W, an ultrasonic frequency of 50kHz, and an ultrasonic temperature of 50℃ to disperse the nano zinc borate evenly and prepare a zinc borate flame retardant slurry with a mass fraction of 5.7%. Finally, the flame retardant slurry was added to the modified cationic starch solution, so that the mass ratio of zinc borate flame retardant slurry to cationic starch was 1.77:1. Under the conditions of 90℃ and 100r / min, the mixture was magnetically stirred for 5min to make the zinc borate flame retardant slurry and the modified cationic starch solution evenly mixed, thus obtaining the adhesive with added zinc borate. (2) The specific preparation method of the adhesive with added magnesium hydroxide is as follows: First, polyvinyl alcohol is added to ultrapure water to obtain a 2% polyvinyl alcohol solution. Under the conditions of constant temperature at 90℃ and 100r / min, the mixture is magnetically stirred for 30min to make the polyvinyl alcohol completely dissolved. Cationic starch is added to the polyvinyl alcohol solution, so that the mass ratio of polyvinyl alcohol to cationic starch is 0.66:1. Under the conditions of 95℃ and 100r / min, the mixture is magnetically stirred for 20min to make the cationic starch completely gelatinized, thus obtaining the modified cationic starch solution. Then, nano-magnesium hydroxide was dissolved in ultrapure water and treated for 10 minutes under ultrasonic power of 800W, ultrasonic frequency of 50kHz, and ultrasonic temperature of 50℃ to ensure uniform dispersion of the nano-magnesium hydroxide, thus preparing a magnesium hydroxide flame retardant slurry with a mass fraction of 5.7%. Finally, the flame retardant slurry was added to a modified cationic starch solution, making the mass ratio of magnesium hydroxide flame retardant slurry to cationic starch 1.77:1. The mixture was then magnetically stirred for 5 minutes at 90℃ and a rotation speed of 100r / min to ensure uniform mixing of the magnesium hydroxide flame retardant slurry and the modified cationic starch solution, thus obtaining an adhesive with added magnesium hydroxide.

[0044] The original adhesive refers to an adhesive without polyvinyl alcohol. The preparation method involves adding cationic starch to ultrapure water to obtain a 5% cationic starch solution. The solution is then magnetically stirred for 20 minutes at 95℃ and 100 rpm to completely gelatinize the cationic starch.

[0045] Immersion treatment refers to soaking kraft paper in a prepared soaking solution. This soaking solution refers to the modified solution in patent CN109183502A (Preparation method and application of an acid- and mildew-resistant modified solution for paper cultural relic archives). The specific preparation process is as follows in Example 2 of that patent: Step 1, sodium polyphosphate, soluble magnesium carbonate, barium carbonate, borax, and sodium octaborate tetrahydrate are mixed in a mass ratio of 40:16:14:10:20 to obtain a mixture. Water, at a mass of 35 times the mixture, is added, and the mixture is heated and stirred at 90°C until completely dissolved to obtain a mixed solution. Step 2, sodium carbonate (15% by mass), sodium fluoride (10% by mass), and potassium sorbate sodium fluoride (8% by mass) are added to the mixed solution. The mixture is kept at a constant temperature and stirred until completely dissolved and clear, yielding an acid- and mildew-resistant modified solution.

[0046] A. Solid content test The solid content of the adhesive was tested using a gravimetric method. 5 mL of the newly prepared adhesive and the original adhesive were each dropped onto a petri dish. The mass of the petri dish was recorded as M1, and the total mass of the petri dish and adhesive was recorded as M2. The petri dishes with adhesive were placed in a dry, ventilated environment until the adhesive was completely dry, and the total mass was recorded as M3. The solid content of the adhesive was calculated using formula (1). Three parallel experiments were set up for each group.

[0047] (1) Solid content refers to the amount of non-volatile substances in an adhesive, expressed as a mass fraction. Solid content is a fundamental factor in adhesive strength and an important indicator of an adhesive's performance. Low solid content leads to insufficient cohesion in the adhesive, resulting in decreased adhesive strength; furthermore, lower solid content means more moisture needs to evaporate during drying, leading to a longer curing time. Test results show that adding modified cationic starch increased the solid content of the adhesive from 2.56% to 5.08%. This increase in solid content enhances the adhesive's cohesion, thereby increasing adhesive strength.

[0048] B. Bond strength and water resistance test After soaking, the kraft paper was cut into strips 100mm long and 15mm wide, with a 30mm section bonded together using adhesive. After drying at room temperature, the samples were placed in a desiccator containing a saturated MgCl2 solution for 24 hours to equilibrate. The bond strength was tested by applying force parallel to the length of the paper strip to determine the maximum breaking force per unit width. The experiment was conducted using a Guangzhou-made QT-1136 universal testing machine, with tensile tests performed at a strain rate of 2 mm / min. Each data set was repeated five times.

[0049] After soaking, the kraft paper was cut into strips 100mm long and 15mm wide, with a 30mm section bonded together using adhesive. After drying at room temperature, the strips were placed in an aging chamber at 99% RH and 25℃. After 24 hours, they were removed, dried again at room temperature, and then placed in a desiccator containing a saturated MgCl2 solution for equilibration for 24 hours. The adhesive strength was tested by applying force parallel to the length of the paper strip to determine the maximum breaking force per unit width. A Guangzhou-made QT-1136 universal testing machine was used for tensile testing at a strain rate of 2 mm / min, with each set of data repeated five times.

[0050] like Figure 1 As shown, the adhesive strength was evaluated using a tensile test. The results showed that adding a single flame retardant to the adhesive substrate resulted in a slight decrease in adhesive strength. In contrast, the paperboard sample treated with the adhesive prepared in Example 1 exhibited stronger tensile strength than the sample treated with a single flame retardant. Observation of the stretched paperboard revealed that fractures in all adhesive samples did not occur at the bond joints. This demonstrates that the adhesive strength of all three adhesives exceeded the inherent strength of the paper. These results indicate that the adhesive prepared in Example 1 has better bonding ability than the adhesive with a single flame retardant added.

[0051] like Figure 1 As shown, the waterproof performance of the adhesive was evaluated using a tensile test. The results showed that the adhesive strength of the sample without any added flame retardant decreased significantly after aging. In contrast, the adhesive strength of the adhesive with added zinc borate decreased less after aging, while the decrease was greater with added magnesium hydroxide. This is because magnesium hydroxide has a hydrophilic surface. The cardboard sample treated with the adhesive prepared in Example 1 showed less decrease in adhesive strength after aging and still maintained high strength. These results indicate that the waterproof performance of the adhesive prepared in Example 1 is better than that of the adhesive with added single flame retardant material.

[0052] C. Combustion performance test The soaked kraft paper was cut into 210mm × 70mm pieces and laminated together using different adhesives. After drying at room temperature, the samples were placed in a desiccator containing a saturated MgCl2 solution for 24 hours to equilibrate. The flammability of the samples was tested according to GB / T 14656—2009 "Test Method for Flame Retardant Paper and Paperboard". Each set of data was repeated five times.

[0053] like Figure 2As shown, the flammability of the adhesive was evaluated using a vertical burning test. The results showed that when appropriate amounts of nano-magnesium hydroxide and nano-zinc borate were added alone to the adhesive substrate, the samples exhibited a more pronounced flaming combustion state. However, after adding a composite flame retardant to the adhesive substrate, both the afterflame time and ignition time of the samples decreased, especially the afterflame time, indicating that the samples with the composite flame retardant had good self-extinguishing properties. Furthermore, the char length test results showed that the char length of the samples with the composite flame retardant was significantly shorter, indicating better flame retardant performance. These results demonstrate that the adhesive prepared in Example 1 has better flame retardant capabilities than the adhesive with a single flame retardant material.

[0054] D. Thermal stability analysis The laminated cardboard was cut into 1mm × 1mm fragments, and the thermal stability of the samples was tested using a Themys One thermogravimetric analyzer. The experiment was conducted under a nitrogen atmosphere, with a temperature range of 30-800℃, a heating rate of 20℃ / min, and a sample mass of 10-15mg.

[0055] like Figure 3 As shown, the thermal stability of the adhesive was evaluated using thermogravimetric analysis (TGA). The results showed that none of the four samples exhibited significant thermal weight loss below 300℃, indicating little difference in their thermal stability within this temperature range. The main decomposition range was 300–360℃. Looking at the final weight loss, the kraft paper treated with the adhesive containing nano-magnesium hydroxide had a residual rate of only 19.92%, while the kraft paper treated with the adhesive containing nano-zinc borate had a residual rate of 34.06%. In contrast, the kraft paper treated with the adhesive prepared in Example 1 had a residual rate that increased to 40.98%. These results indicate that the composite flame-retardant system can form more and more stable char residue at high temperatures, demonstrating a good synergistic flame-retardant effect between nano-zinc borate and nano-magnesium hydroxide.

[0056] In summary, the modified cationic starch of this invention increases the solid content of the adhesive, thereby improving its bonding strength. Adding appropriate amounts of nano-magnesium hydroxide and nano-zinc borate to the modified cationic starch significantly enhances its flame-retardant properties without affecting the adhesive strength. Furthermore, the addition of these two nano-magnesium hydroxide and nano-zinc borate synergistically improves the adhesive's water resistance. Archival containers made with the adhesive of this invention can significantly delay flame spread and suppress smoldering, reducing the direct threat of external fires to the archives inside, while maintaining the long-term stability of the container structure, thus providing longer-lasting and more effective protection for the archives.

Claims

1. An adhesive that combines flame retardancy and high bonding strength, characterized in that, The adhesive is made of polyvinyl alcohol-modified cationic starch and a flame retardant slurry. The mass ratio of polyvinyl alcohol to cationic starch is 0.6~1:1; The mass ratio of the flame retardant slurry to cationic starch is 1.7~2:

1.

2. A method for preparing an adhesive that combines flame retardancy and high adhesive strength, characterized in that, Includes the following steps: S1. Prepare a polyvinyl alcohol solution; S2. Add cationic starch to polyvinyl alcohol solution to obtain modified cationic starch solution; S3. Mix nano-magnesium hydroxide and nano-zinc borate, and ultrasonically treat to prepare flame retardant slurry; S4. Add the flame retardant slurry to the modified cationic starch solution.

3. The method for preparing an adhesive with both flame retardancy and high adhesive strength according to claim 2, characterized in that, In step S1, polyvinyl alcohol is added to ultrapure water to obtain a polyvinyl alcohol solution with a mass fraction of 2% to 2.2%. The solution is then magnetically stirred for 25 to 30 minutes at a constant temperature of 90 to 95°C and a rotation speed of 70 to 100 r / min to completely dissolve the polyvinyl alcohol.

4. The method for preparing an adhesive with both flame retardancy and high adhesive strength according to claim 2, characterized in that, In step S2, the cationic starch is magnetically stirred for 20-30 minutes at a temperature of 95-100℃ and a rotation speed of 70-100 r / min to completely gelatinize it.

5. The method for preparing an adhesive with both flame retardancy and high adhesive strength according to claim 2, characterized in that, In step S3, a mixture of nano-magnesium hydroxide and nano-zinc borate is dissolved in ultrapure water and treated for 10-15 minutes under ultrasonic power of 700-800W, ultrasonic frequency of 40-50kHz, and ultrasonic temperature of 50-60℃ to ensure uniform dispersion of nano-magnesium hydroxide and nano-zinc borate.

6. The method for preparing an adhesive with both flame retardancy and high adhesive strength according to claim 5, characterized in that, The mass ratio of the nano-magnesium hydroxide to the nano-zinc borate is 2.5~3:

1.

7. The method for preparing an adhesive with both flame retardancy and high adhesive strength according to claim 2, characterized in that, In step S4, the flame retardant slurry and the modified cationic starch solution are magnetically stirred for 5 to 10 minutes at a temperature of 90 to 95°C and a rotation speed of 70 to 100 r / min to ensure uniform mixing.

8. The application of an adhesive prepared by the method of any one of claims 2-7, which combines flame retardancy and high adhesive strength, in archival equipment.

9. A method for applying an adhesive that combines flame retardancy and high bonding strength in archival equipment, characterized in that, The adhesive is applied to the archival equipment by brushing or dotting.

10. The method for applying an adhesive with both flame retardancy and high bonding strength as described in claim 9 in archival storage, characterized in that, The adhesive layer thickness is 0.15~0.2mm, and the curing temperature for brushing or dispensing is 25~28℃.

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