Water-based adhesive as well as preparation method and application thereof

Abstract

The invention discloses a water-based adhesive and a preparation method and application thereof, the water-based adhesive comprises the following raw material components: a composite bio-based gel system, a compound cross-linking agent, a functional additive and water, the composite bio-based gel system is a mixture of modified chitosan, sodium alginate and nanocellulose, the compound cross-linking agent is a mixture of citric acid and polyethylene glycol diglycidyl ether. According to the invention, a modified chitosan-sodium alginate-nanocellulose composite system is used as a gelling core and is matched with a citric acid-polyethylene glycol diglycidyl ether compound cross-linking agent, and a functional auxiliary agent is used as an auxiliary agent, and under the combined action of the composite bio-based gelling system, the compound cross-linking agent and the functional auxiliary agent, the hydrogel is prepared. The water-based adhesive which is high in bonding strength, low in friction sensitivity, good in wide temperature range stability, flame-retardant, anti-static and environment-friendly can be obtained, can be widely applied to various bonding scenes in firework preparation, such as firework paper reel bonding, component combination or lead fixing processes, and is high in use value and good in application prospect.

Description

Technical Field

[0001] This invention belongs to the field of fireworks auxiliary material preparation technology, and relates to a water-based adhesive, its preparation method and application. Background Technology

[0002] Fireworks, also known as fireworks, are often used in grand ceremonies and performances and are very popular.

[0003] The existing structure of fireworks mainly includes an inner tube for loading pyrotechnic powder, which is placed inside an outer tube. Multiple outer tubes are arranged in an array, and the pyrotechnic powder inside the inner tube is connected by a lead wire. Each outer tube is fixed inside an outer box.

[0004] Adhesives are needed in the manufacturing process of fireworks. For example, the inner tube is made by bonding multiple layers of cardboard with adhesive, and each outer tube also needs to be bonded together with adhesive. At the same time, the fuse also needs to be fixed with adhesive.

[0005] Existing adhesives mainly include starch-based adhesives and polyvinyl alcohol (PVA) water-based adhesives. Among them, starch-based adhesives have shortcomings such as easy mold growth and low bonding strength. In addition, existing PVA water-based adhesives also have shortcomings such as poor moisture resistance, insufficient bonding strength, poor compatibility with pyrotechnics, and easy freezing at low temperatures.

[0006] For the reasons stated above, this invention is proposed. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a water-based adhesive with high bonding strength, low friction sensitivity, good stability over a wide temperature range, flame retardant and antistatic properties, and green and environmentally friendly properties, as well as its preparation method and application.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A water-based adhesive, comprising the following raw material components: a composite bio-based gelling system, a compound crosslinking agent, functional additives, and water; wherein the composite bio-based gelling system is a mixture of modified chitosan, sodium alginate, and nanocellulose; and the compound crosslinking agent is a mixture of citric acid and polyethylene glycol diglycidyl ether.

[0009] In a further improvement of the above-mentioned water-based adhesive, the mass ratio of modified chitosan, sodium alginate, and nanocellulose in the composite bio-based gelling system is 3-5:2-4:1-2.

[0010] In a further improvement of the above-mentioned water-based adhesive, the modified chitosan is carboxymethylated modified chitosan; the degree of substitution of the carboxymethylated modified chitosan is 0.85 to 1.15.

[0011] In a further improvement of the above-mentioned water-based adhesive, the mass ratio of citric acid to polyethylene glycol diglycidyl ether in the compound crosslinking agent is 1 to 3:1.

[0012] In a further improvement to the above-mentioned water-based adhesive, the functional additives include microencapsulated flame retardants and static eliminators; the mass percentage of the microencapsulated flame retardants in the functional additives is 60% to 80%.

[0013] In a further improvement to the above-mentioned water-based adhesive, the microencapsulated flame retardant has a particle size of 50 nm to 200 nm.

[0014] In a further improvement of the above-mentioned water-based adhesive, the microencapsulated flame retardant is a magnesium hydroxide microcapsule coated with red phosphorus; and the static eliminator is a polyether-modified organosilicon.

[0015] The aforementioned water-based adhesive, further improved, also includes a film-forming aid, wherein the film-forming aid comprises 0.5% to 1.5% of the total mass of the water-based adhesive; the film-forming aid is propylene glycol methyl ether acetate.

[0016] The above-mentioned water-based adhesive is further improved in that the raw material components in the water-based adhesive are expressed as follows by mass percentage: Composite bio-based gelling system 8%–15%, Compound crosslinking agent 2%–5%, Functional additives: 3%–8%, the remainder is deionized water.

[0017] The above-mentioned water-based adhesive is further improved to meet the following properties: pH value of 5.5 to 7.0, viscosity of 2500 mPa·s to 4000 mPa·s, solid content ≥28%, adhesive strength ≥2.2 MPa, friction sensitivity ≤8%, and performance degradation rate ≤10% after 12 months of storage in an environment of -10℃ to 50℃.

[0018] As a general technical concept, the present invention also provides a method for preparing the above-mentioned water-based adhesive, comprising the following steps: S1. Add modified chitosan and sodium alginate to deionized water and stir to obtain mixed gel solution A; S2. Add nanocellulose to mixed adhesive solution A and stir to obtain a composite bio-based gelling system; S3. Add the compound crosslinking agent to the composite bio-based gelation system in three equal portions to carry out the crosslinking reaction, and obtain mixed adhesive solution B. S4. Add the functional additives to the mixed adhesive solution B for degassing treatment to obtain water-based adhesive.

[0019] In a further improvement to the above preparation method, in step S1, the stirring is carried out at a temperature of 50℃~60℃ and a rotation speed of 200r / min~300r / min; the stirring time is 35 min~50 min.

[0020] In a further improvement to the above preparation method, in step S2, the stirring is carried out at a temperature of 25℃~35℃ and a rotation speed of 1200r / min~1400r / min; the stirring time is 40 min~50 min.

[0021] In a further improvement to the above preparation method, in step S3, the composite crosslinking agent is added every 20 minutes; during the addition of the composite crosslinking agent, the temperature is maintained at 45℃~55℃ and the stirring rate is 200 r / min~300 r / min; the crosslinking reaction process also includes introducing nitrogen gas into the system; the nitrogen gas introduction rate is 0.5 L / min~1.0 L / min; and the crosslinking reaction time is 30 min~35 min.

[0022] In a further improvement to the above preparation method, in step S4, the degassing treatment is carried out at a temperature of 30℃~35℃; the degassing treatment is carried out under a vacuum of -0.08MPa~-0.06MPa; and the degassing treatment time is 20 min~30 min.

[0023] As a general technical concept, the present invention also provides the application of the above-described water-based adhesive or the water-based adhesive prepared by the above-described preparation method in the preparation of fireworks.

[0024] Compared with the prior art, the advantages of the present invention are as follows: (1) In view of the shortcomings of existing polyvinyl alcohol water-based adhesives, such as poor moisture resistance, insufficient bonding strength, poor compatibility with pyrotechnics and easy freezing at low temperature, the present invention creatively provides a water-based adhesive, which includes the following raw material components: a composite bio-based gelling system, a compound crosslinking agent, a functional additive and water, wherein the composite bio-based gelling system is a mixture of modified chitosan, sodium alginate and nanocellulose, and the compound crosslinking agent is a mixture of citric acid and polyethylene glycol diglycidyl ether. In this invention, a modified chitosan-sodium alginate-nanocellulose composite system is used as the gelling core. Modified chitosan and sodium alginate form a dual-network or composite cross-linking system through electrostatic interactions and ionic cross-linking, combined with the hydrogen bond network of nanocellulose. This significantly improves the mechanical strength and toughness of the hydrogel while maintaining a uniform porous structure. Combined with a citric acid-polyethylene glycol diglycidyl ether composite cross-linking agent, the diepoxy groups of polyethylene glycol diglycidyl ether undergo a ring-opening reaction with the carboxyl / hydroxyl groups of citric acid, generating a dense three-dimensional network structure. This improves cohesive strength and chemical resistance. More importantly, in composite biological... The composite system constructed by the combined action of the base gelling system, the compound crosslinking agent, and the functional additives can significantly improve the tensile strength, thermal stability, and hygroscopicity, as well as reduce crystallinity and optimize the material flexibility. It can also improve water resistance, mechanical strength, and biocompatibility, while optimizing reaction conditions to adapt to specific application scenarios. As a result, a water-based adhesive with high bonding strength, low friction sensitivity, good stability over a wide temperature range, flame retardant and antistatic properties, and environmental friendliness can be obtained. This water-based adhesive can be widely used in various bonding scenarios in fireworks preparation, such as the bonding of fireworks paper rolls, component assembly, or lead wire fixing processes. It has high use value and good application prospects. Compared with conventional polyvinyl alcohol water-based adhesives, the water-based adhesive of this invention achieves the following unexpected technical effects: the bonding strength can be increased by 83.3% to 133.3%, and the bonding strength is ≥2.2MPa; the friction sensitivity can be reduced by 52.3% to 66.0%, and the friction sensitivity is ≤8%; it has good stability over a wide temperature range, and the performance degradation rate is ≤10% after 12 months of storage in an environment of -10℃ to 50℃.

[0025] (2) In the water-based adhesive of the present invention, the mass ratio of modified chitosan, sodium alginate and nanocellulose in the composite bio-based gelling system is 3-5:2-4:1-2, which is beneficial to improving the overall performance of the water-based adhesive, such as higher mechanical strength, better structural uniformity and stronger functional properties.

[0026] (3) In the water-based adhesive of the present invention, the mass ratio of citric acid to polyethylene glycol diglycidyl ether in the compound crosslinking agent is 1 to 3:1, which can significantly improve the crosslinking density, mechanical strength and functional stability of the material, while reducing the reaction temperature and enhancing biocompatibility, and reducing energy consumption.

[0027] (4) The present invention also provides a method for preparing water-based adhesive. By adding raw materials in a distributed manner, it is beneficial to control the performance of water-based adhesive and finally obtain water-based adhesive with high bonding strength, low friction sensitivity, good stability over a wide temperature range, flame retardant and antistatic properties, and green environmental protection. In particular, by optimizing and controlling process conditions such as temperature, time, stirring method and speed, it is also possible to ensure that water-based adhesive with excellent performance is prepared, which is convenient for the industrial application of water-based adhesive. Detailed Implementation

[0028] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0029] The raw materials and instruments used in the following examples are all commercially available; unless otherwise specified, the equipment and preparation processes used are conventional equipment and conventional processes.

[0030] Example 1 A water-based adhesive comprises the following raw material components: a composite bio-based gelling system, a compound crosslinking agent, functional additives, and water, wherein the composite bio-based gelling system is a mixture of modified chitosan, sodium alginate, and nanocellulose, and the compound crosslinking agent is a mixture of citric acid and polyethylene glycol diglycidyl ether.

[0031] In this embodiment, the mass ratio of modified chitosan, sodium alginate and nanocellulose in the composite bio-based gelling system is 4:3:1.5.

[0032] In this embodiment, the modified chitosan used is carboxymethylated modified chitosan (commercially available product), and the degree of substitution of the carboxymethylated modified chitosan is 1.0.

[0033] In this embodiment, the nanocellulose used is a commercially available product, such as TL-003, but not limited to it. The TL-003 product has the following characteristics: solid content 2.5-4%, fiber diameter ≤100 nm, length 500 nm-20 μm, pH value 6-8, appearance as a white or milky white gel, and storage conditions at room temperature or refrigeration.

[0034] In this embodiment, the mass ratio of citric acid to polyethylene glycol diglycidyl ether in the composite crosslinking agent is 2:1.

[0035] In this embodiment, the functional additives used include microencapsulated flame retardants and static eliminators, wherein the mass percentage of microencapsulated flame retardants in the functional additives is 73%.

[0036] In this embodiment, the microencapsulated flame retardant used has a particle size of 100 nm and is magnesium hydroxide microcapsules coated with red phosphorus (commercially available product); the static eliminator is polyether-modified organosilicon (commercially available product).

[0037] In this embodiment, a film-forming aid is also included, wherein the film-forming aid is 1% of the total mass of the water-based adhesive; the film-forming aid is propylene glycol methyl ether acetate.

[0038] In this embodiment, the raw material components in the water-based adhesive are expressed as follows by mass percentage: Composite bio-based gelling system 8.5%, 3% of the compound crosslinking agent Functional additives: 5.5%, the remainder is deionized water.

[0039] A method for preparing the water-based adhesive in Example 1 above includes the following steps: S1. Add modified chitosan and sodium alginate to deionized water and stir for 35 minutes at a temperature of 55℃ and a speed of 250r / min until completely dissolved to obtain mixed adhesive solution A.

[0040] S2. Add nanocellulose to the mixed adhesive solution A, and disperse it at high speed for 40 minutes at a temperature of 28℃ and a rotation speed of 1250r / min until it is completely dispersed to obtain a composite bio-based gelling system.

[0041] S3. Under the conditions of 45℃, stirring rate of 250r / min and nitrogen gas introduction rate of 0.8L / min, the compound crosslinking agent is added every 20min. The compound crosslinking agent is added to the composite bio-based gelation system in three equal portions to carry out the crosslinking reaction. After the addition is completed, the reaction continues for 30min to obtain mixed adhesive solution B.

[0042] S4. Add the functional additive to the mixed adhesive solution B, and perform degassing treatment for 20 min at a temperature of 32℃ and a vacuum degree of -0.07MPa to obtain water-based adhesive.

[0043] The performance of the water-based adhesive prepared in Example 1 was tested (test standards: GB / T 11175-2002, GB18583-2008, GB / T 2793-1995, GB 18094-2000), and the results are as follows: (1) pH value 6.4, viscosity 3200 mPa·s (25℃), solid content 30.2%; adhesive strength 2.5 MPa, friction sensitivity 6.8%.

[0044] (2) Stored at 10℃ for 12 months: adhesive strength 2.3MPa (attenuation rate 8%), viscosity 3000mPa·s.

[0045] (3) Stored at 50℃ for 12 months: adhesive strength 2.4MPa (attenuation rate 4%), no sagging.

[0046] (4) Flame retardant rating V-0 (limiting oxygen index LOI=35%), electrostatic voltage ≤500V.

[0047] (5) Formaldehyde content ≤ 0.1g / kg, VOC content ≤ 50g / L.

[0048] An application of the above-mentioned water-based adhesive in the preparation of fireworks, for example, using the water-based adhesive for the bonding of fireworks paper rolls, component assembly, or lead wire fixing processes.

[0049] Example 2 A water-based adhesive comprises the following raw material components: a composite bio-based gelling system, a compound crosslinking agent, functional additives, and water, wherein the composite bio-based gelling system is a mixture of modified chitosan, sodium alginate, and nanocellulose, and the compound crosslinking agent is a mixture of citric acid and polyethylene glycol diglycidyl ether.

[0050] In this embodiment, the mass ratio of modified chitosan, sodium alginate, and nanocellulose in the composite bio-based gelling system is 3:2:1.

[0051] In this embodiment, the modified chitosan used is carboxymethylated chitosan (commercially available product), and the degree of substitution of the carboxymethylated chitosan is 0.85.

[0052] In this embodiment, the nanocellulose used is a commercially available product, such as TL-003, but not limited to it. The TL-003 product has the following characteristics: solid content 2.5-4%, fiber diameter ≤100 nm, length 500 nm-20 μm, pH value 6-8, appearance as a white or milky white gel, and storage conditions at room temperature or refrigeration.

[0053] In this embodiment, the mass ratio of citric acid to polyethylene glycol diglycidyl ether in the compound crosslinking agent is 1:1.

[0054] In this embodiment, the functional additives used include microencapsulated flame retardants and static eliminators, wherein the mass percentage of microencapsulated flame retardants in the functional additives is 75%.

[0055] In this embodiment, the microencapsulated flame retardant used has a particle size of 50 nm and is magnesium hydroxide microcapsules coated with red phosphorus (commercially available product); the static eliminator is polyether-modified organosilicon (commercially available product).

[0056] In this embodiment, a film-forming aid is also included, wherein the film-forming aid is 1% of the total mass of the water-based adhesive; the film-forming aid is propylene glycol methyl ether acetate.

[0057] In this embodiment, the raw material components in the water-based adhesive are expressed as follows by mass percentage: 12% of the composite bio-based gelling system 2% of the compound crosslinking agent Functional additives: 4%, the remainder is deionized water.

[0058] A method for preparing the water-based adhesive in Example 2 above includes the following steps: S1. Add modified chitosan and sodium alginate to deionized water and stir for 40 minutes at 50℃ and 200r / min until completely dissolved to obtain mixed solution A.

[0059] S2. Add nanocellulose to the mixed adhesive solution A, and disperse it at high speed for 45 minutes at a temperature of 25℃ and a speed of 1300r / min until it is completely dispersed to obtain a composite bio-based gelling system.

[0060] S3. Under the conditions of 55℃, 200 r / min stirring rate and 0.5 L / min nitrogen gas introduction rate, the compound crosslinking agent is added every 20 min. The compound crosslinking agent is added to the composite bio-based gelation system in three equal portions to carry out the crosslinking reaction. After the addition is completed, the reaction continues for 25 min to obtain mixed gel B.

[0061] S4. Add the functional additive to the mixed adhesive solution B, and perform degassing treatment for 30 min at a temperature of 30℃ and a vacuum degree of -0.06MPa to obtain water-based adhesive.

[0062] The performance of the water-based adhesive prepared in Example 2 was tested (test standards: GB / T 11175-2002, GB18583-2008, GB / T 2793-1995, GB 18094-2000), and the results are as follows: (1) pH value 5.8, viscosity 2800 mPa·s (25℃), solid content 28.5%; adhesive strength 2.2 MPa, friction sensitivity 7.5%.

[0063] (2) Stored at 10℃ for 12 months: adhesive strength 2.0MPa (attenuation rate 9%), no freezing phenomenon.

[0064] (3) Stored at 50℃ for 12 months: adhesive strength 2.1MPa (attenuation rate 4.5%).

[0065] (4) Flame retardant rating V-0 (LOI=33%), electrostatic voltage ≤600V.

[0066] (5) Formaldehyde content ≤ 0.08 g / kg, VOC content ≤ 45 g / L.

[0067] An application of the above-mentioned water-based adhesive in the preparation of fireworks, for example, using the water-based adhesive for the bonding of fireworks paper rolls, component assembly, or lead wire fixing processes.

[0068] Example 3 A water-based adhesive comprises the following raw material components: a composite bio-based gelling system, a compound crosslinking agent, functional additives, and water, wherein the composite bio-based gelling system is a mixture of modified chitosan, sodium alginate, and nanocellulose, and the compound crosslinking agent is a mixture of citric acid and polyethylene glycol diglycidyl ether.

[0069] In this embodiment, the mass ratio of modified chitosan, sodium alginate, and nanocellulose in the composite bio-based gelling system is 5:4:2.

[0070] In this embodiment, the modified chitosan used is carboxymethylated chitosan (commercially available product), and the degree of substitution of the carboxymethylated chitosan is 1.15.

[0071] In this embodiment, the nanocellulose used is a commercially available product, such as TL-003, but not limited to it. The TL-003 product has the following characteristics: solid content 2.5-4%, fiber diameter ≤100 nm, length 500 nm-20 μm, pH value 6-8, appearance as a white or milky white gel, and storage conditions at room temperature or refrigeration.

[0072] In this embodiment, the mass ratio of citric acid to polyethylene glycol diglycidyl ether in the composite crosslinking agent is 3:1.

[0073] In this embodiment, the functional additives used include microencapsulated flame retardants and static eliminators, wherein the mass percentage of microencapsulated flame retardants in the functional additives is 75%.

[0074] In this embodiment, the microencapsulated flame retardant used has a particle size of 50 nm and is magnesium hydroxide microcapsules coated with red phosphorus (commercially available product); the static eliminator is polyether-modified organosilicon (commercially available product).

[0075] In this embodiment, a film-forming aid is also included, wherein the film-forming aid accounts for 1.5% of the total mass of the water-based adhesive; the film-forming aid is propylene glycol methyl ether acetate.

[0076] In this embodiment, the raw material components in the water-based adhesive are expressed as follows by mass percentage: Composite bio-based gelling system 11%, 4% of the compound crosslinking agent Functional additives account for 8%, and the remainder is deionized water.

[0077] A method for preparing the water-based adhesive in Example 3 above includes the following steps: S1. Add modified chitosan and sodium alginate to deionized water and stir for 50 min at 60℃ and 300 r / min until completely dissolved to obtain mixed solution A.

[0078] S2. Add nanocellulose to the mixed adhesive solution A, and disperse it at high speed for 50 minutes at a temperature of 35℃ and a rotation speed of 1400r / min until it is completely dispersed to obtain a composite bio-based gelling system.

[0079] S3. Under the conditions of 50℃, 300 r / min stirring rate and 1.0 L / min nitrogen gas introduction rate, the compound crosslinking agent is added every 20 min. The compound crosslinking agent is added to the composite bio-based gelation system in three equal portions to carry out the crosslinking reaction. After the addition is completed, the reaction continues for 35 min to obtain mixed gel B.

[0080] S4. Add the functional additive to the mixed adhesive solution B, and perform degassing treatment for 25 min at a temperature of 35℃ and a vacuum degree of -0.08MPa to obtain water-based adhesive.

[0081] The performance of the water-based adhesive prepared in Example 3 was tested (test standards: GB / T 11175-2002, GB18583-2008, GB / T 2793-1995, GB 18094-2000), and the results are as follows: (1) pH value 6.8, viscosity 3800 mPa·s (25℃), solid content 32.1%; adhesive strength 2.8 MPa, friction sensitivity 5.2%.

[0082] (2) Stored at 10℃ for 12 months: adhesive strength 2.6MPa (attenuation rate 7.1%).

[0083] (3) Stored at 50℃ for 12 months: adhesive strength 2.7MPa (attenuation rate 3.6%).

[0084] (4) Flame retardant rating V-0 (LOI=38%), electrostatic voltage ≤400V.

[0085] (5) Formaldehyde content ≤ 0.05 g / kg, VOC content ≤ 40 g / L.

[0086] An application of the above-mentioned water-based adhesive in the preparation of fireworks, for example, using the water-based adhesive for the bonding of fireworks paper rolls, component assembly, or lead wire fixing processes.

[0087] Comparative Example 1 A polyvinyl alcohol water-based adhesive, with the following raw material composition by mass fraction: polyvinyl alcohol 10%, borax 2%, talc 5%, and deionized water 83%.

[0088] Performance test data: Adhesive strength 1.2MPa, friction sensitivity 15.3%.

[0089] It will freeze after one month when stored at 10℃, and will drip after one month when stored at 50℃.

[0090] Flame retardant rating: None (LOI=22%), electrostatic voltage: ≥1500V.

[0091] Formaldehyde content 0.3g / kg, VOC content ≥120g / L.

[0092] As can be seen from the above results, the water-based adhesives prepared in Examples 1-3 of this invention are significantly superior to existing polyvinyl alcohol water-based adhesives in terms of bonding strength (increased by 83.3%-133.3%), friction sensitivity (reduced by 52.3%-66.0%), wide temperature range stability, flame retardant and antistatic properties, and environmental friendliness. Moreover, they are environmentally friendly and non-toxic (harmful substances comply with GB 18583-2008 standards), suitable for various bonding scenarios of fireworks, and the preparation process is simple and suitable for industrial production, solving the core pain points of existing technologies.

[0093] Therefore, in this invention, a modified chitosan-sodium alginate-nanocellulose composite system is used as the gelling core, combined with a citric acid-polyethylene glycol diglycidyl ether crosslinking agent, and supplemented with functional additives. Under the combined action of the composite bio-based gelling system, the crosslinking agent, and the functional additives, a water-based adhesive with high bonding strength, low friction sensitivity, good stability over a wide temperature range, flame retardant and antistatic properties, and environmental friendliness can be obtained. It can be widely used in various bonding scenarios in fireworks preparation, such as fireworks paper roll bonding, component assembly, or lead wire fixing processes, etc. It has high use value and good application prospects.

[0094] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A water-based adhesive, characterized in that, The water-based adhesive comprises the following raw material components: a composite bio-based gelling system, a compound crosslinking agent, functional additives, and water; the composite bio-based gelling system is a mixture of modified chitosan, sodium alginate, and nanocellulose; the compound crosslinking agent is a mixture of citric acid and polyethylene glycol diglycidyl ether.

2. The water-based adhesive according to claim 1, characterized in that, In the composite bio-based gelling system, the mass ratio of modified chitosan, sodium alginate, and nanocellulose is 3-5:2-4:1-2; the modified chitosan is carboxymethylated modified chitosan; and the degree of substitution of the carboxymethylated modified chitosan is 0.85-1.

15.

3. The water-based adhesive according to claim 1, characterized in that, The mass ratio of citric acid to polyethylene glycol diglycidyl ether in the compound crosslinking agent is 1 to 3:

1.

4. The water-based adhesive according to claim 1, characterized in that, The functional additives include microencapsulated flame retardants and static eliminators; the mass percentage of the microencapsulated flame retardant in the functional additives is 60% to 80%; the particle size of the microencapsulated flame retardant is 50 nm to 200 nm; the microencapsulated flame retardant is magnesium hydroxide microcapsules coated with red phosphorus; and the static eliminator is polyether-modified organosilicon.

5. The water-based adhesive according to claim 1, characterized in that, It also includes a film-forming aid, which is 0.5% to 1.5% of the total mass of the water-based adhesive; the film-forming aid is propylene glycol methyl ether acetate.

6. The water-based adhesive according to any one of claims 1 to 5, characterized in that, The raw material components in the water-based adhesive, expressed as a mass percentage, are as follows: Composite bio-based gelling system 8%–15%, Compound crosslinking agent 2%–5%, Functional additives: 3%–8%, the remainder is deionized water.

7. The water-based adhesive according to claim 6, characterized in that, The water-based adhesive meets the following properties: pH value of 5.5 to 7.0, viscosity of 2500 mPa·s to 4000 mPa·s, solid content ≥28%, adhesive strength ≥2.2 MPa, friction sensitivity ≤8%, and performance degradation rate ≤10% after 12 months of storage at -10℃ to 50℃.

8. A method for preparing a water-based adhesive as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Add modified chitosan and sodium alginate to deionized water and stir to obtain mixed gel solution A; S2. Add nanocellulose to mixed adhesive solution A and stir to obtain a composite bio-based gelling system; S3. Add the compound crosslinking agent to the composite bio-based gelation system in three equal portions to carry out the crosslinking reaction, and obtain mixed adhesive solution B. S4. Add the functional additives to the mixed adhesive solution B for degassing treatment to obtain water-based adhesive.

9. The preparation method according to claim 8, characterized in that, In step S1, the stirring is carried out at a temperature of 50℃~60℃ and a rotation speed of 200r / min~300r / min; the stirring time is 35 min~50 min. In step S2, the stirring is carried out at a temperature of 25℃~35℃ and a rotation speed of 1200r / min~1400r / min; the stirring time is 40 min~50 min. In step S3, the compound crosslinking agent is added every 20 minutes; during the addition of the compound crosslinking agent, the temperature is maintained at 45℃~55℃ and the stirring rate is 200 r / min~300 r / min; the crosslinking reaction also includes introducing nitrogen gas into the system; the nitrogen gas introduction rate is 0.5 L / min~1.0 L / min; the crosslinking reaction time is 30 min~35 min. In step S4, the degassing treatment is carried out at a temperature of 30℃ to 35℃; the degassing treatment is carried out under a vacuum of -0.08MPa to -0.06MPa; and the degassing treatment time is 20 min to 30 min.

10. The application of a water-based adhesive as described in any one of claims 1 to 7 or a water-based adhesive prepared by the preparation method described in claim 8 or 9 in the preparation of fireworks.