Polyurethane hot melt adhesive as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of hot melt adhesives, and discloses a polyurethane hot melt adhesive as well as a preparation method and application thereof. The polyurethane hot melt adhesive is prepared from the following raw materials: polyester polyol, polyether polyol, fluorine-containing dihydric alcohol, isocyanate, a chain extender, a catalyst and a modified montmorillonite antibacterial filler, the preparation method of the modified montmorillonite antibacterial filler comprises the following steps: modifying montmorillonite through sulfur-containing amino acid, increasing the interlayer spacing of the montmorillonite through an intercalator, entering the interlayer spacing of the montmorillonite through a metal organic framework synthesized by imidazole or an imidazole derivative and zinc salt, and carrying out surface modification to obtain the modified montmorillonite antibacterial filler. A silver-ammonia solution is treated by a reducing agent, so that the nano-silver is loaded on the montmorillonite and in the surface, the skeleton and the pores of the MOFs material. The polyurethane hot melt adhesive disclosed by the invention not only has high peel strength, but also has excellent waterproofness and lasting antibacterial property.

Description

Technical Field

[0001] The present invention belongs to the technical field of hot melt adhesives, and in particular relates to a polyurethane hot melt adhesive and a preparation method and application thereof. Background Art

[0002] When heated and melted to a certain temperature, hot melt adhesive becomes a fluid, viscous liquid. After cooling and solidifying, it can bond to substrates. It is highly sought after for its ease of use, environmental friendliness, and ease of storage. Polyurethane hot melt adhesives are typically formulated with thermoplastic polyurethane elastomers as a base component and other additives. Because polyurethane hot melt adhesives contain -NCO, they react with many functional groups containing active hydrogen to form chemical bonds, resulting in strong adhesion to a wide range of substrates. In recent years, this type of adhesive has seen rapid growth and is widely used in various industries, including automotive, electronics, and packaging.

[0003] In recent years, with the increasing demand for lightweight and environmentally friendly products, higher performance requirements have been placed on polyurethane hot melt adhesives used in product bonding. These typically include improved waterproofing and antibacterial properties. However, existing polyurethane hot melt adhesives rely heavily on the inherent properties of polyurethane or the addition of common fillers. However, the addition of large amounts of fillers can easily lead to agglomeration, affecting mechanical properties and failing to meet the diverse performance requirements of polyurethane hot melt adhesives. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a polyurethane hot melt adhesive and its preparation method and application. The polyurethane hot melt adhesive of the present invention not only has high peel strength, but also has excellent water resistance and long-lasting antibacterial properties.

[0005] A first aspect of the present invention provides a polyurethane hot melt adhesive, wherein the raw materials for preparing the polyurethane hot melt adhesive include: polyester polyol, polyether polyol, fluorinated diol, isocyanate, chain extender, catalyst and modified montmorillonite antibacterial filler;

[0006] The modified montmorillonite antibacterial filler is prepared by a preparation method comprising the following steps:

[0007] S1, mixing a sulfur-containing amino acid, montmorillonite and a solvent, stirring to react, and filtering to obtain modified montmorillonite;

[0008] S2, mixing the modified montmorillonite, the intercalation agent and the solvent, stirring to react, and filtering to obtain the modified intercalated montmorillonite;

[0009] S3, mixing the modified intercalated montmorillonite, imidazole or an imidazole derivative, a zinc salt and a solvent, stirring to react, and filtering to obtain a modified MOFs intercalated montmorillonite;

[0010] S4. Mixing the modified MOFs intercalated montmorillonite, silver ammonia solution and reducing agent solution, subjecting the mixture to microwave treatment and ultraviolet irradiation, filtering and drying to obtain the modified montmorillonite antibacterial filler.

[0011] In some embodiments of the present invention, the raw materials for preparing the polyurethane hot melt adhesive include, by mass: 35-40 parts of polyester polyol, 25-30 parts of polyether polyol, 10-20 parts of fluorinated diol, 30-35 parts of isocyanate, 2-5 parts of chain extender, 0.1-0.5 parts of catalyst and 4-8 parts of modified montmorillonite antibacterial filler.

[0012] In some embodiments of the present invention, the polyester polyol includes at least one of polybutylene adipate-1,4-diol, polypropylene carbonate diol and polycaprolactone diol; and / or, the polyether polyol includes at least one of polytetramethylene glycol, polyoxypropylene glycol and polyethylene glycol; and / or, the fluorine-containing diol includes at least one of 3-fluoro-1,2-propylene glycol, 2,2,3,3-tetrafluoro-1,4-butane diol and 2,2,3,3,4,4-hexafluoro-1,5-pentane diol; and / or, the isocyanate includes at least one of diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; and / or, the chain extender includes at least one of ethylene glycol, 1,4-butanediol and 1,3-butanediol; and / or, the catalyst includes dibutyltin dilaurate or stannous octoate.

[0013] In some embodiments of the present invention, the sulfur-containing amino acid includes at least one of methionine, cystine and cysteine; and / or the montmorillonite includes at least one of sodium montmorillonite, calcium montmorillonite, magnesium montmorillonite and hydrogen montmorillonite; and / or the solvent includes water and / or an organic solvent; and / or the intercalant includes at least one of a quaternary ammonium salt, a quaternary phosphonium salt and a cationic surfactant; and / or the imidazole derivative includes at least one of 2-methylimidazole, 2-isopropylimidazole and 2-propylimidazole; and / or the zinc salt includes at least one of zinc nitrate, zinc sulfate, zinc acetate and zinc bromide.

[0014] In some embodiments of the present invention, in step S1, the mass ratio of the sulfur-containing amino acid to the montmorillonite is 1:(5-10), the stirring reaction temperature is 55-65° C., and the stirring reaction time is 1-1.5 h.

[0015] In some embodiments of the present invention, in the step S2, the mass ratio of the modified montmorillonite to the intercalant is 1:(1.5-3), the stirring reaction temperature is 60-80° C., and the stirring reaction time is 2-4 h.

[0016] In some embodiments of the present invention, in the step S3, the mass ratio of the modified intercalated montmorillonite, the imidazole or imidazole derivative and the zinc salt is (1-5):(3-8):1, the stirring reaction temperature is 40-60°C, and the stirring reaction time is 8-12h.

[0017] In some embodiments of the present invention, in the step S4, the mass volume ratio of the modified MOFs intercalated montmorillonite, the silver ammonia solution and the reducing agent solution is (0.5-1) g:1 mL:(8-12) mL.

[0018] In some embodiments of the present invention, the concentration of silver ions in the silver ammonia solution is 0.05-0.2 mol / L.

[0019] In some embodiments of the present invention, the reducing agent in the reducing agent solution includes at least one of polyvinyl pyrrolidone, ascorbic acid and oxalic acid.

[0020] In some embodiments of the present invention, the reducing agent solution is a polyvinyl pyrrolidone solution, wherein the concentration of polyvinyl pyrrolidone is 0.1-0.2 mol / L.

[0021] In some embodiments of the present invention, the power of the microwave treatment is 500-700 W, and the time of the microwave treatment is 1-5 min.

[0022] In some embodiments of the present invention, the wavelength of the ultraviolet light irradiation is 256-365 nm, and the time of the ultraviolet light irradiation is 3-12 h.

[0023] The second aspect of the present invention provides a method for preparing the polyurethane hot melt adhesive according to the first aspect of the present invention, comprising the following steps:

[0024] S1, mixing polyester polyol, polyether polyol, fluorinated diol and chain extender, stirring for reaction, and vacuum dehydrating to obtain a mixture;

[0025] S2. Under nitrogen protection, add isocyanate and catalyst to the mixture, stir to react, then add modified montmorillonite antibacterial filler, continue stirring to obtain the polyurethane hot melt adhesive.

[0026] In some embodiments of the present invention, in step S1 of the method for preparing the polyurethane hot melt adhesive, the stirring reaction temperature is 110-130° C., the stirring reaction time is 10-30 min, and the vacuum dehydration time is 1-3 h.

[0027] In some embodiments of the present invention, in step S2 of the method for preparing the polyurethane hot melt adhesive, the stirring reaction temperature is 80-100° C., the stirring reaction time is 1-2 h, and the continued stirring time is 0.5-1 h.

[0028] The third aspect of the present invention provides applications of the polyurethane hot melt adhesive described in the first aspect of the present invention in the automotive industry, electronic products, packaging, and construction fields.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The polyurethane hot melt adhesive of the present invention is synthesized using polyester polyol, polyether polyol and isocyanate as main raw materials; fluorine-containing diol is introduced into the raw materials. Since fluorine atoms have low surface energy and migrate to the surface of the substrate during the formation of the hot melt adhesive, the surface energy is reduced and the hydrophobicity is improved. In addition, the fluorine atoms have large steric hindrance and shielding effects, which can effectively protect the surrounding carbamate bonds (the polyurethane molecular chain contains a large number of easily hydrolyzed carbamate bonds) from hydrolysis, thereby improving the water resistance. At the same time, the steric hindrance of the relative movement of fluorine atoms in the polyurethane molecular chain during the heating process is increased, the molecular chains are kept relatively dense, the penetration of water molecules is reduced, and the water resistance is further improved.

[0031] The raw materials of the polyurethane hot melt adhesive of the present invention also introduce modified montmorillonite antibacterial filler, the montmorillonite is modified by sulfur-containing amino acids, the sulfur-containing groups are used to react with silver ions to enhance the adsorption capacity of silver ions, and the intercalation agent is used to increase the interlayer spacing of the montmorillonite, so that the metal organic framework (MOFs, ZIF-8) synthesized by imidazole or imidazole derivatives and zinc salts can enter the interlayer spacing of the montmorillonite. In addition, there are a large number of hydroxyl groups between the layers of the montmorillonite, and the MOFs material synthesized between the layers can more fully form hydrogen bonds with the hydroxyl groups, and The lamellar structure of montmorillonite can protect MOFs materials to a certain extent, making MOFs materials less likely to fall off. The nanosilver obtained by reducing silver ions can be evenly loaded on the montmorillonite and the surface, skeleton and pores of MOFs materials, avoiding the spontaneous agglomeration of nanosilver particles and having little effect on mechanical properties. Through the coordinated effect of sulfur-containing groups and MOFs materials, the carrying capacity of silver ions is increased, making it difficult for silver ions to be freed during long-term use, reducing the loss rate of silver ions during use, and achieving efficient and long-lasting antibacterial properties. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below by way of specific examples. Unless otherwise specified, the raw materials, reagents, or devices used in the examples are all commercially available or can be obtained by conventional methods. Unless otherwise specified, all experiments or testing methods are conventional methods in the art.

[0033] Example 1

[0034] A polyurethane hot melt adhesive comprising the following raw materials in parts by weight: 38 parts of polyester polyol, 28 parts of polyether polyol, 15 parts of fluorinated diol, 32 parts of isocyanate, 3 parts of chain extender, 0.3 parts of catalyst, and 6 parts of modified montmorillonite antibacterial filler;

[0035] Among them, the polyester polyol is poly(1,4-butylene adipate) diol; the polyether polyol is polytetramethylene glycol; the fluorine-containing diol is 2,2,3,3-tetrafluoro-1,4-butanediol; the isocyanate is diphenylmethane diisocyanate; the chain extender is ethylene glycol; and the catalyst is dibutyltin dilaurate.

[0036] The preparation method of the polyurethane hot melt adhesive comprises the following steps:

[0037] S1. Mix polyester polyol, polyether polyol, fluorinated diol and chain extender, stir and react at 120° C. for 20 min, and vacuum dehydrate for 2 h to obtain a mixture;

[0038] S2. Under nitrogen protection, add isocyanate and catalyst to the mixture, stir and react at 90°C for 1.5 hours, then add modified montmorillonite antibacterial filler, continue stirring for 0.8 hours, and obtain polyurethane hot melt adhesive.

[0039] The preparation method of the modified montmorillonite antibacterial filler comprises the following steps:

[0040] S1. Mix cystine, sodium montmorillonite, and water, stir and react at 60° C. for 1.2 h, and filter to obtain modified montmorillonite; wherein the mass ratio of cystine to sodium montmorillonite is 1:8;

[0041] S2. Mixing modified montmorillonite, octadecyltrimethylammonium chloride and water, stirring and reacting at 70° C. for 3 h, and filtering to obtain modified intercalated montmorillonite; wherein the mass ratio of the modified montmorillonite to octadecyltrimethylammonium chloride is 1:2;

[0042] S3, dispersing the modified intercalated montmorillonite in water to obtain a modified intercalated montmorillonite dispersion, dissolving 2-methylimidazole and zinc nitrate in methanol and then adding the mixture to the modified intercalated montmorillonite dispersion, stirring and reacting at 50° C. for 10 hours, and filtering to obtain a modified MOFs intercalated montmorillonite; wherein the mass ratio of the modified intercalated montmorillonite, 2-methylimidazole, and zinc nitrate is 3:5:1;

[0043] S4. The modified MOFs intercalated montmorillonite, 0.1 mol / L silver ammonia solution and 0.15 mol / L polyvinyl pyrrolidone solution were mixed, subjected to microwave treatment and ultraviolet irradiation, filtered and dried to obtain a modified montmorillonite antibacterial filler; wherein the mass volume ratio of the modified MOFs intercalated montmorillonite, silver ammonia solution and polyvinyl pyrrolidone solution was 0.8 g:1 mL:10 mL, the microwave treatment power was 600 W, the microwave treatment time was 3 min, the ultraviolet irradiation wavelength was 365 nm, and the ultraviolet irradiation time was 8 h.

[0044] Example 2

[0045] A polyurethane hot melt adhesive comprising the following raw materials in parts by weight: 35 parts of polyester polyol, 25 parts of polyether polyol, 10 parts of fluorinated diol, 30 parts of isocyanate, 2 parts of chain extender, 0.1 part of catalyst, and 4 parts of modified montmorillonite antibacterial filler;

[0046] Among them, the polyester polyol is polypropylene carbonate diol; the polyether polyol is polypropylene oxide diol; the fluorine-containing diol is 2,2,3,3-tetrafluoro-1,4-butane diol; the isocyanate is hexamethylene diisocyanate; the chain extender is 1,4-butanediol; and the catalyst is dibutyltin dilaurate.

[0047] The preparation method of the polyurethane hot melt adhesive comprises the following steps:

[0048] S1. Mix polyester polyol, polyether polyol, fluorinated diol and chain extender, stir and react at 110° C. for 10 min, and vacuum dehydrate for 1 h to obtain a mixture;

[0049] S2. Under nitrogen protection, add isocyanate and catalyst to the mixture, stir and react at 80°C for 1 hour, then add modified montmorillonite antibacterial filler, continue stirring for 0.5 hour, and obtain polyurethane hot melt adhesive.

[0050] The preparation method of the modified montmorillonite antibacterial filler comprises the following steps:

[0051] S1. Mix cystine, sodium montmorillonite and water, stir and react at 55° C. for 1 hour, and filter to obtain modified montmorillonite; wherein the mass ratio of cystine to sodium montmorillonite is 1:5;

[0052] S2. Mixing modified montmorillonite, octadecyltrimethylammonium chloride and water, stirring and reacting at 60° C. for 2 h, and filtering to obtain modified intercalated montmorillonite; wherein the mass ratio of the modified montmorillonite to octadecyltrimethylammonium chloride is 1:1.5;

[0053] S3, dispersing the modified intercalated montmorillonite in water to obtain a modified intercalated montmorillonite dispersion, dissolving 2-methylimidazole and zinc nitrate in methanol and then adding the mixture to the modified intercalated montmorillonite dispersion, stirring and reacting at 40° C. for 8 h, and filtering to obtain a modified MOFs intercalated montmorillonite; wherein the mass ratio of the modified intercalated montmorillonite, 2-methylimidazole, and zinc nitrate is 1:3:1;

[0054] S4. The modified MOFs intercalated montmorillonite, 0.05 mol / L silver ammonia solution and 0.1 mol / L polyvinyl pyrrolidone solution were mixed, subjected to microwave treatment and ultraviolet irradiation, filtered and dried to obtain a modified montmorillonite antibacterial filler; wherein, the mass volume ratio of the modified MOFs intercalated montmorillonite, silver ammonia solution and polyvinyl pyrrolidone solution was 0.5 g:1 mL:8 mL, the microwave treatment power was 500 W, the microwave treatment time was 5 min, the ultraviolet irradiation wavelength was 365 nm, and the ultraviolet irradiation time was 10 h.

[0055] Example 3

[0056] A polyurethane hot melt adhesive comprising the following raw materials in parts by weight: 40 parts of polyester polyol, 30 parts of polyether polyol, 20 parts of fluorinated diol, 35 parts of isocyanate, 5 parts of chain extender, 0.5 parts of catalyst, and 8 parts of modified montmorillonite antibacterial filler;

[0057] Among them, the polyester polyol is polycaprolactone diol; the polyether polyol is polyethylene glycol; the fluorine-containing diol is 2,2,3,3,4,4-hexafluoro-1,5-pentanediol; the isocyanate is isophorone diisocyanate; the chain extender is ethylene glycol; and the catalyst is dibutyltin dilaurate.

[0058] The preparation method of the polyurethane hot melt adhesive comprises the following steps:

[0059] S1. Mix polyester polyol, polyether polyol, fluorinated diol and chain extender, stir and react at 130° C. for 30 min, and vacuum dehydrate for 3 h to obtain a mixture;

[0060] S2. Under nitrogen protection, add isocyanate and catalyst to the mixture, stir and react at 100°C for 2 hours, then add modified montmorillonite antibacterial filler, continue stirring for 1 hour, and obtain polyurethane hot melt adhesive.

[0061] The preparation method of the modified montmorillonite antibacterial filler comprises the following steps:

[0062] S1. Mix cystine, sodium montmorillonite and water, stir and react at 65° C. for 1.5 h, and filter to obtain modified montmorillonite; wherein the mass ratio of cystine to sodium montmorillonite is 1:10;

[0063] S2. Mixing modified montmorillonite, octadecyltrimethylammonium chloride and water, stirring and reacting at 80° C. for 4 hours, and filtering to obtain modified intercalated montmorillonite; wherein the mass ratio of the modified montmorillonite to octadecyltrimethylammonium chloride is 1:3;

[0064] S3. Dispersing the modified intercalated montmorillonite in water to obtain a modified intercalated montmorillonite dispersion, dissolving 2-methylimidazole and zinc nitrate in methanol and then adding the mixture to the modified intercalated montmorillonite dispersion, stirring and reacting at 60° C. for 12 hours, and filtering to obtain a modified MOFs intercalated montmorillonite; wherein the mass ratio of the modified intercalated montmorillonite, 2-methylimidazole, and zinc nitrate is 5:8:1;

[0065] S4. The modified MOFs intercalated montmorillonite, 0.2 mol / L silver ammonia solution and 0.2 mol / L polyvinyl pyrrolidone solution were mixed, subjected to microwave treatment and ultraviolet irradiation, filtered and dried to obtain a modified montmorillonite antibacterial filler; wherein the mass volume ratio of the modified MOFs intercalated montmorillonite, silver ammonia solution and polyvinyl pyrrolidone solution was 1 g:1 mL:12 mL, the microwave treatment power was 700 W, the microwave treatment time was 4 min, the ultraviolet irradiation wavelength was 365 nm, and the ultraviolet irradiation time was 12 h.

[0066] Comparative Example 1

[0067] The difference from Example 1 is that an equal amount of 2,2,3,3-tetrafluoro-1,4-butanediol is replaced by propylene glycol, and the remaining raw materials, amounts and preparation method are the same as in Example 1.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that in the preparation method of the modified montmorillonite antibacterial filler, step S1 is not performed, that is, cystine is not used to modify the sodium montmorillonite. The remaining raw materials, amounts and preparation method are the same as in Example 1.

[0070] Comparative Example 3

[0071] The difference from Example 1 is that in the preparation method of the modified montmorillonite antibacterial filler, step S2 is not performed, that is, octadecyltrimethylammonium chloride is not used to intercalate the modified montmorillonite. The remaining raw materials, amounts and preparation method are the same as in Example 1.

[0072] Comparative Example 4

[0073] The difference from Example 1 is that in the preparation method of the modified montmorillonite antibacterial filler, step S3 is not performed, that is, MOFs synthesis is not performed, and the remaining raw materials, amounts and preparation methods are the same as in Example 1.

[0074] Comparative Example 5

[0075] The difference from Example 1 is that in the preparation method of the modified montmorillonite antibacterial filler, step S4 is adjusted to directly perform conventional physical mixing of the modified MOFs intercalated montmorillonite and nanosilver, that is, no silver ammonia solution reduction is performed, and the remaining raw materials, amounts and preparation methods are the same as in Example 1.

[0076] Polyurethane hot melt adhesive performance test

[0077] Mechanical properties: The elongation at break of the polyurethane hot melt adhesives prepared in the examples and comparative examples was tested using a universal testing machine at 25° C. and 50% relative humidity. The test values ​​are recorded in Table 1.

[0078] Peel strength: The polyurethane hot melt adhesives prepared in the examples and comparative examples were subjected to T-peel strength bonding tests with reference to standard GB / T 2791-1995. The initial tack and final tack were measured, and the test values ​​are recorded in Table 1.

[0079] Waterproofness: The surface waterproofness of the polyurethane hot melt adhesives prepared in the examples and comparative examples was tested by the sessile drop method. The test drop size was 2.5 μL and the test time was 15 s. The surface water contact angle was obtained and the test values ​​were recorded in Table 1.

[0080] Antibacterial property: The antibacterial zone method was used for testing. The test bacteria were Staphylococcus aureus (ATCC6538) and Escherichia coli (ATCC8739). The test samples were the adhesive discs (5 mm in diameter and 1 mm in thickness) of the polyurethane hot melt adhesive prepared in the examples and comparative examples after curing. 200 μL of activated bacterial solution (the same amount of concentration was 10 6 cfu / mL of Staphylococcus aureus suspension and Escherichia coli suspension), place the adhesive disc in the center of the culture dish, culture in a cell culture incubator at 37°C for 24 hours, and measure the diameter A of the inhibition zone; in addition, place the test sample in a constant temperature and humidity chamber (45°C, 90% RH) for 28 days, then test it again, and measure the diameter B of the inhibition zone; the test values ​​are recorded in Table 1.

[0081] Table 1 Performance test results

[0082]

[0083] From the data results in Table 1, it can be seen that Examples 1-3 of the present application have advantages over Comparative Examples 1-5 in terms of mechanical properties, peel strength, waterproof properties, antibacterial properties and long-term antibacterial properties, especially the advantages in waterproofness and antibacterial properties are more obvious; this is mainly due to the combined effect of the fluorinated diols and modified montmorillonite antibacterial fillers added as defined in the present application, while Comparative Examples 1-5 did not adopt the technical solution defined in the present application, resulting in obvious disadvantages in the above performance tests, which also shows the necessity of the technical solution defined in the present application for the technical effects of the present application and solving the technical problems.

[0084] The above specifically describes the preferred embodiments of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A polyurethane hot melt adhesive, characterized in that: The raw materials for preparing the polyurethane hot melt adhesive include: polyester polyol, polyether polyol, fluorine-containing diol, isocyanate, chain extender, catalyst and modified montmorillonite antibacterial filler; The modified montmorillonite antibacterial filler is prepared by a preparation method comprising the following steps: S1, mixing a sulfur-containing amino acid, montmorillonite and a solvent, stirring to react, and filtering to obtain modified montmorillonite; S2, mixing the modified montmorillonite, the intercalation agent and the solvent, stirring to react, and filtering to obtain the modified intercalated montmorillonite; S3, mixing the modified intercalated montmorillonite, imidazole or an imidazole derivative, a zinc salt and a solvent, stirring to react, and filtering to obtain a modified MOFs intercalated montmorillonite; S4. Mixing the modified MOFs intercalated montmorillonite, silver ammonia solution and reducing agent solution, subjecting the mixture to microwave treatment and ultraviolet irradiation, filtering and drying to obtain the modified montmorillonite antibacterial filler.

2. The polyurethane hot melt adhesive according to claim 1, characterized in that: The raw materials for preparing the polyurethane hot melt adhesive include, by mass, 35-40 parts of polyester polyol, 25-30 parts of polyether polyol, 10-20 parts of fluorine-containing diol, 30-35 parts of isocyanate, 2-5 parts of chain extender, 0.1-0.5 parts of catalyst and 4-8 parts of modified montmorillonite antibacterial filler.

3. The polyurethane hot melt adhesive according to claim 1, characterized in that: The polyester polyol includes at least one of polybutylene adipate-1,4-diol, polypropylene carbonate diol and polycaprolactone diol; and / or, the polyether polyol includes at least one of polytetramethylene glycol, polyoxypropylene glycol and polyethylene glycol; and / or, the fluorine-containing diol includes at least one of 3-fluoro-1,2-propylene glycol, 2,2,3,3-tetrafluoro-1,4-butane diol and 2,2,3,3,4,4-hexafluoro-1,5-pentane diol; and / or, the isocyanate includes at least one of diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; and / or, the chain extender includes at least one of ethylene glycol, 1,4-butanediol and 1,3-butanediol; and / or, the catalyst includes dibutyltin dilaurate or stannous octoate.

4. The polyurethane hot melt adhesive according to claim 1, characterized in that: The sulfur-containing amino acid includes at least one of methionine, cystine and cysteine; and / or the montmorillonite includes at least one of sodium montmorillonite, calcium montmorillonite, magnesium montmorillonite and hydrogen montmorillonite; and / or the solvent includes water and / or an organic solvent; and / or the intercalant includes at least one of a quaternary ammonium salt, a quaternary phosphonium salt and a cationic surfactant; and / or the imidazole derivative includes at least one of 2-methylimidazole, 2-isopropylimidazole and 2-propylimidazole; and / or the zinc salt includes at least one of zinc nitrate, zinc sulfate, zinc acetate and zinc bromide.

5. The polyurethane hot melt adhesive according to claim 1, characterized in that: In the step S1, the mass ratio of the sulfur-containing amino acid to the montmorillonite is 1:(5-10), the stirring reaction temperature is 55-65° C., and the stirring reaction time is 1-1.5 h.

6. The polyurethane hot melt adhesive according to claim 1, characterized in that: In the step S2, the mass ratio of the modified montmorillonite to the intercalant is 1:(1.5-3), the temperature of the stirring reaction is 60-80° C., and the time of the stirring reaction is 2-4 hours.

7. The polyurethane hot melt adhesive according to claim 1, characterized in that: In the step S3, the mass ratio of the modified intercalated montmorillonite, the imidazole or imidazole derivative and the zinc salt is (1-5):(3-8):1, the stirring reaction temperature is 40-60°C, and the stirring reaction time is 8-12h.

8. The polyurethane hot melt adhesive according to claim 1, characterized in that: In the step S4, the mass volume ratio of the modified MOFs intercalated montmorillonite, the silver ammonia solution and the reducing agent solution is (0.5-1) g:1 mL:(8-12) mL.

9. The method for preparing the polyurethane hot melt adhesive according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, mixing polyester polyol, polyether polyol, fluorinated diol and chain extender, stirring for reaction, and vacuum dehydrating to obtain a mixture; S2. Under nitrogen protection, add isocyanate and catalyst to the mixture, stir to react, then add modified montmorillonite antibacterial filler, continue stirring to obtain the polyurethane hot melt adhesive.

10. Use of the polyurethane hot melt adhesive according to any one of claims 1 to 8 in the fields of automobile industry, electronic products, packaging, and construction.

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