Antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane and its preparation method and application

Abstract

The invention belongs to the technical field of waterborne polyurethane, discloses antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane, is prepared by the system consisting of the following raw materials in parts by weight: 200-400 parts of castor oil, 100-300 parts of dicyclohexylmethane diisocyanate, 70-150 parts of hexamethylene diisocyanate, 70-150 parts of N-methyldiethanolamine, 100-400 parts of polyol acid, 7000-10000 parts of water and 5-15 parts of catalyst. The present invention replaces acetic acid as a cationic neutralizer with polyol acid, not only can form an ionic bond with N-methyldiethanolamine, the hydrophilicity of the enhanced polyurethane segment is ensured to be smoothly carried out in the emulsification process, and the quaternary ammonium salt formed makes the material have antibacterial property. The polyol acid rich in alcohol hydroxyl group and carboxyl group can be self-assembled into nanoclusters by intermolecular hydrogen bonds to make the waterborne polyurethane material film-forming have self-healing and recyclable performance, while making the material have high toughness and high tensile strength. The invention also discloses a preparation method and application of the vegetable oil-based waterborne polyurethane.

Description

Technical Field

[0001] The present invention belongs to the technical field of waterborne polyurethane, and in particular relates to antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane and a preparation method and application thereof. Background Art

[0002] Waterborne polyurethane uses water as the dispersion medium and has the advantages of low VOC, non-toxicity, and easy processing. It is in line with the development trend of green chemistry. The currently developed waterborne polyurethane materials mainly rely on petroleum-based raw materials. With the increasing depletion of petroleum resources and the intensification of environmental problems, the development of sustainable and environmentally friendly alternative materials has become a research hotspot.

[0003] As a renewable resource, vegetable oil has the advantages of wide availability, low price, and biodegradability, making it an ideal choice to replace petroleum-based raw materials. Through chemical modification, vegetable oil can be introduced with active groups such as hydroxyl groups for the synthesis of waterborne polyurethane. However, vegetable oil-based waterborne polyurethanes are generally inferior to petroleum-based waterborne polyurethanes in terms of mechanical properties, especially exhibiting low toughness and single functionality, which limits their application in high-performance fields. In order to improve the toughness of vegetable oil-based waterborne polyurethane films, core-shell structured particles such as acrylic core-shell particles are often introduced into waterborne polyurethanes to improve the toughness of the material through a stress dispersion mechanism. However, this method is complicated to operate, has a general effect on improving the toughness of vegetable oil-based waterborne polyurethanes, and it is difficult to achieve material functional diversity in the design of this method. Therefore, there is an urgent need to design vegetable oil-based waterborne polyurethanes with improved toughness and multifunctionality. Summary of the Invention

[0004] The purpose of the present invention is to provide an antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane and its preparation method and application, so as to solve the technical problems of low toughness and single functionality of vegetable oil-based waterborne polyurethane in the prior art.

[0005] The first aspect of the present invention provides an antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane, which is prepared from a system consisting of the following raw materials, measured in parts by weight: 200-400 parts of castor oil, 100-300 parts of dicyclohexylmethane diisocyanate, 70-150 parts of hexamethylene diisocyanate, 70-150 parts of N-methyldiethanolamine, 100-400 parts of polyol acid, 7000-10,000 parts of water, and 5-15 parts of a catalyst.

[0006] The antibacterial, self-toughening, self-healing and recyclable plant oil-based waterborne polyurethane of the present invention uses a polyol acid rich in alcoholic hydroxyl groups and carboxyl groups as a raw material. The polyol acid, as a small molecule neutralizer, can not only form an ionic bond with the tertiary amine of N-methyldiethanolamine to enhance the hydrophilicity of the polyurethane chain segment, thereby enabling the waterborne polyurethane to smoothly undergo hydrophilic and hydrophobic assembly to transform into a waterborne polyurethane emulsion during the emulsification process, but also, during the film-forming process of the antibacterial, self-toughening, self-healing and recyclable plant oil-based waterborne polyurethane, the alcoholic hydroxyl groups and carboxyl groups on the polyol acid can self-assemble to form nanoclusters through intermolecular hydrogen bonding to enhance the toughness of the plant oil-based waterborne polyurethane itself.

[0007] In some embodiments, the polyol acid contains 1 to 9 alcoholic hydroxyl groups and 1 to 4 carboxyl groups.

[0008] In some embodiments, the polyol acid includes at least one of lactobionic acid, mucic acid, sialic acid, tartaric acid, citric acid, and D-gluconic acid.

[0009] In some embodiments, the catalyst is an organotin catalyst; preferably, the catalyst is selected from at least one of dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin dioctoate.

[0010] In some embodiments, the molar ratio of the polyol acid to N-methyldiethanolamine is 0.6:1 to 1.1:1.

[0011] In some embodiments, the antimicrobial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane has a solid content of 10% to 30%.

[0012] A second aspect of the present invention provides a method for preparing an antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane, comprising the following steps:

[0013] S1. reacting dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and N-methyldiethanolamine at 80-85° C. for 0.5-2 h to obtain a prepolymer;

[0014] S2. Add castor oil to the prepolymer and react for 1.5-2 hours to obtain a reaction system;

[0015] S3, adding a catalyst to the reaction system, and reacting until the reaction system no longer has fluidity;

[0016] S4, adding an organic solvent to the reaction system, reacting for 1.5-2 hours, and cooling to room temperature to obtain a polyurethane solution system;

[0017] S5. Dissolve the polyol acid in water to obtain an aqueous solution of the polyol acid, add the aqueous solution of the polyol acid into the polyurethane solution system, emulsify, and then remove the organic solvent by rotary evaporation to obtain the product.

[0018] The antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane of the present invention first undergoes a prepolymerization reaction of N-methyldiethanolamine, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate to obtain a prepolymer terminated with -NCO groups. Castor oil, a green and environmentally friendly bio-based material, is then introduced, and proton transfer between polyol acid and N-methyldiethanolamine is performed to form ionic bonds. This not only enhances the hydrophilicity of the polyurethane chain segments to facilitate emulsification, but also allows the polyol acid to self-assemble to form nanoclusters. The preparation method is simple.

[0019] In some embodiments, in step S4, the organic solvent is selected from at least one of acetone and butanone.

[0020] In some embodiments, in step S4, the amount of the organic solvent used is 20-40 mL.

[0021] In some embodiments, in step S5, the rotation speed used for emulsification is 800-1000 r / min, and the emulsification time is 1-2 h.

[0022] The third aspect of the present invention provides an application of an antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane, which can be used to prepare coatings, antibacterial materials, and adhesives.

[0023] In some embodiments, the antibacterial, self-toughening, self-healing, recyclable plant oil-based waterborne polyurethane can be used to prepare coatings, antibacterial materials, and adhesives with recyclability, self-healing ability, high tensile strength, and high toughness.

[0024] The beneficial effects of the present invention are:

[0025] (1) The antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethane of the present invention uses polyol acid to replace traditional acetic acid as a cationic neutralizer. Not only can it form ionic bonds with N-methyldiethanolamine to enhance the hydrophilicity of the polyurethane chain segments and ensure a smooth emulsification process, but also, during the film-forming process, the polyol acid, rich in alcohol hydroxyl and carboxyl groups, can self-assemble into nanoclusters through intermolecular hydrogen bonds. This in-situ phase separation structure can improve the toughness of the waterborne polyurethane itself, making the waterborne polyurethane material have high toughness and high tensile strength.

[0026] (2) The present invention utilizes a simple preparation process and is easy to operate. The prepared waterborne polyurethane has good antibacterial effect after film formation, and has self-healing and recyclable properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1These are photos of the appearance of the emulsions of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethanes of Examples 1-3 of the present invention and the vegetable oil-based waterborne polyurethane of Comparative Example 1;

[0028] Figure 2 FT-IR images of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethanes of Examples 1-3 of the present invention, the vegetable oil-based waterborne polyurethane of Comparative Example 1, and lactobionic acid;

[0029] Figure 3 TEM images of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane of Example 1 of the present invention and the vegetable oil-based waterborne polyurethane film of Comparative Example 1;

[0030] Figure 4 Graphs showing the mechanical properties of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane films of Examples 1-3 of the present invention and the vegetable oil-based waterborne polyurethane film of Comparative Example 1;

[0031] Figure 5 The self-healing performance test results of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane films of Examples 1-3 of the present invention and the vegetable oil-based waterborne polyurethane film of Comparative Example 1 are shown;

[0032] Figure 6 The recovery of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film according to Example 1 of the present invention;

[0033] Figure 7 This is a diagram showing the antibacterial effects of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane of Example 1 of the present invention and the vegetable oil-based waterborne polyurethane film of Comparative Example 1. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto. The raw materials and reagents involved in the following examples can all be obtained from commercial channels.

[0035] Example 1

[0036] This embodiment provides an antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane, which is prepared by the following steps:

[0037] At 80 ° C, 1.70 g of dicyclohexylmethane diisocyanate, 1.09 g of hexamethylene diisocyanate and 1.03 g of N-methyldiethanolamine was added to a dry two-necked flask and reacted for 2 hours to obtain a prepolymer. 3.00 g of castor oil was added to the prepolymer and the reaction was continued for 2 hours to obtain a reaction system. 0.05 g of dibutyltin dilaurate was then added to the reaction system as a catalyst. The reaction was continued until the reaction system no longer had fluidity. 30 mL of butanone was added to dilute the concentration of the reaction system and the reaction was continued for 2 hours. The temperature of the reaction system was then lowered from 80°C to room temperature to obtain a polyurethane solution system. 1.86 g of lactobionic acid was dissolved in 78.22 g of deionized water to obtain an aqueous solution of lactobionic acid. The aqueous solution of lactobionic acid was added to the polyurethane solution system. The polyurethane solution system was emulsified by vigorous stirring at 800-1000 r / min for 2 hours. The butanone was removed by a rotary evaporator to obtain an antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane. The solid content of the obtained waterborne polyurethane emulsion was 10%.

[0038] Example 2

[0039] This embodiment provides an antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane, which is prepared by the following steps:

[0040] At 80 ° C, 1.70 g of dicyclohexylmethane diisocyanate, 1.09 g of hexamethylene diisocyanate and 1.03 g of N-methyldiethanolamine was added to a dry two-necked flask and reacted for 2 hours to obtain a prepolymer. 3.00 g of castor oil was added to the prepolymer and the reaction was continued for 2 hours to obtain a reaction system. 0.05 g of dibutyltin dilaurate was then added to the reaction system as a catalyst. The reaction was continued until the reaction system no longer had fluidity. 30 mL of butanone was added to dilute the concentration of the reaction system and the reaction was continued for 2 hours. The temperature of the reaction system was then lowered from 80°C to room temperature to obtain a polyurethane solution system. 2.79 g of lactobionic acid was dissolved in 86.60 g of deionized water to obtain an aqueous solution of lactobionic acid. The aqueous solution of lactobionic acid was added to the polyurethane solution system. The polyurethane solution system was emulsified by vigorous stirring at 800-1000 r / min for 2 hours. The butanone was removed by a rotary evaporator to obtain an antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane. The solid content of the obtained waterborne polyurethane emulsion was 10%.

[0041] Example 3

[0042] This embodiment provides an antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane, which is prepared by the following steps:

[0043] At 80 ° C, 1.70 g of dicyclohexylmethane diisocyanate, 1.09 g of hexamethylene diisocyanate and 1.03 g of N-methyldiethanolamine was added to a dry two-necked flask and reacted for 2 hours to obtain a prepolymer. 3.00 g of castor oil was added to the prepolymer and the reaction was continued for 2 hours to obtain a reaction system. 0.05 g of dibutyltin dilaurate was then added to the reaction system as a catalyst. The reaction was continued until the reaction system no longer had fluidity. 30 mL of butanone was added to dilute the concentration of the reaction system and the reaction was continued for 2 hours. The temperature of the reaction system was then lowered from 80°C to room temperature to obtain a polyurethane solution system. 3.41 g of lactobionic acid was dissolved in 92.19 g of deionized water to obtain an aqueous solution of lactobionic acid. The aqueous solution of lactobionic acid was added to the polyurethane solution system. The polyurethane solution system was emulsified by vigorous stirring at 800-1000 r / min for 2 hours. The butanone was removed by a rotary evaporator to obtain an antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane. The solid content of the obtained waterborne polyurethane emulsion was 10%.

[0044] Comparative Example 1

[0045] This comparative example provides a vegetable oil-based waterborne polyurethane, which is prepared by the following steps:

[0046] 1.70 g of dicyclohexylmethane diisocyanate, 1.09 g of hexamethylene diisocyanate, and 1.03 g of N-methyldiethanolamine were added to a dry two-necked flask at 80° C. and reacted at 80° C. for 2 h to obtain a prepolymer. 3.00 g of castor oil was added to the prepolymer and the reaction was continued for 2 h to obtain a reaction system. 0.05 g of dibutyltin dilaurate was then added to the reaction system as a catalyst and reacted until the reaction system no longer had fluidity. 30 mL of butanone was then added to dilute the concentration of the reaction system and the reaction was continued for 2 h. The temperature of the reaction system was then lowered from 80° C. to room temperature to obtain a polyurethane solution system. 0.31 g of acetic acid was then dissolved in 64.27 g of deionized water to obtain an acetic acid aqueous solution, which was then added to the polyurethane solution system. The polyurethane solution system was emulsified by vigorous stirring at 800-1000 r / min for 2 h. The butanone was removed by rotary evaporation to obtain a vegetable oil-based waterborne polyurethane. The obtained waterborne polyurethane emulsion had a solid content of 10%.

[0047] Experimental Example 1

[0048] In this experimental example, the antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethanes of Examples 1-3 and the plant oil-based waterborne polyurethane of Comparative Example 1 were observed to study the effect of lactobionic acid content on the appearance of the plant oil-based waterborne polyurethane emulsion.

[0049] The appearance photos of the emulsions of the antibacterial, self-toughening, self-healing, recyclable plant oil-based waterborne polyurethanes of Examples 1-3 and the plant oil-based waterborne polyurethane of Comparative Example 1 are as follows: Figure 1 As shown. Figure 1 As can be seen, the emulsions of Examples 1-3 and Comparative Example 1 all exhibit translucent or transparent appearances. The aqueous polyurethane emulsions of Example 1 and Comparative Example 1 were prepared using the same molar amounts of lactobionic acid and acetic acid, respectively, and both emulsions exhibited similar color and transparency. As the lactobionic acid content increased in Examples 2 and 3, the hydrophilicity of the polyurethane segments increased, resulting in smaller emulsion particle sizes. Consequently, the emulsions of Examples 2 and 3 exhibited higher transparency.

[0050] Experimental Example 2

[0051] In this experimental example, the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethanes of Examples 1-3 and the vegetable oil-based waterborne polyurethane and lactobionic acid of Comparative Example 1 were characterized by infrared spectroscopy.

[0052] The films obtained after evaporation of water from the antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethanes of Examples 1-3 and the plant oil-based waterborne polyurethane of Comparative Example 1 were used as samples, respectively. FT-IR spectroscopy analysis was performed on the different samples of Examples 1-3, Comparative Example 1, and lactobionic acid. The results are as follows: Figure 2 As shown. Figure 2 It can be seen that the FT-IR spectrum of the sample is at 2270 cm -1 There is no characteristic absorption peak corresponding to the -NCO group at any place, which indicates that the isocyanate group in the reactant has been completely consumed. At the same time, the characteristic absorption peak of typical waterborne polyurethane can be observed in the FT-IR spectrum, 3344 cm -1 The vibration absorption band at 2933 cm is attributed to the -NH- of the carbamate bond. -1 and 2845 cm -1 The absorption band at 1714 cm is attributed to the vibration absorption of -CH2-CH2- and -CH3 in the fatty acid chain. -1 The absorption band at 3000~3700 cm corresponds to the C=O stretching vibration of the carbamate bond. -1 The broad peak at 1685~1900 cm is attributed to OH. -1 The infrared peak at 900~1190 cm is attributed to the carbonyl group. -1The large broad peak at 37° belongs to COC, and the infrared peaks of these characteristic groups contained in lactobionic acid all appear in the FT-IR spectra of the samples of Examples 1-3. These typical characteristic absorption bands indicate that the preparation of the antibacterial, self-toughening, self-healing, recyclable vegetable oil-based water-based polyurethanes of Examples 1-3 and the vegetable oil-based water-based polyurethane of Comparative Example 1 is successful.

[0053] Experimental Example 3

[0054] In this experimental example, the antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethane of Example 1 and the plant oil-based waterborne polyurethane of Comparative Example 1 were dried at room temperature, and the films obtained after drying were characterized by transmission electron microscopy (TEM). The results are as follows: Figure 3 Compared with the TEM characterization results of the vegetable oil-based waterborne polyurethane film of Comparative Example 1, it can be clearly observed that lactobionic acid clusters exist in the film of Example 1. This is because lactobionic acid rich in hydroxyl and carboxyl groups self-assembles into nanoclusters through intermolecular hydrogen bonding during the film formation process.

[0055] Experimental Example 4

[0056] In this experimental example, mechanical properties of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethanes of Examples 1-3 and the vegetable oil-based waterborne polyurethane of Comparative Example 1 were tested after curing and film formation.

[0057] Sample preparation: The vegetable oil-based waterborne polyurethane obtained in Examples 1-3 and Comparative Example 1 was dried at room temperature, and the dried film was cut into rectangular samples of 30 mm × 10 mm (length × width).

[0058] Test method: The samples were tested on a tensile testing machine at an extension rate of 50 mm / min to measure the mechanical properties of the film. The indicators include tensile strength, elongation at break and toughness. All samples were tested more than three times in the test, and the data were recorded as the average ± standard deviation. The test results are shown in Table 1 and Figure 4 .

[0059] Table 1 Mechanical properties test

[0060]

[0061] As shown in Table 1, the tensile strength and toughness of the vegetable oil-based waterborne polyurethane film of Comparative Example 1 were 2.15 MPa and 2.71 MJ·m -3The mechanical property test results of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane films of Examples 1-3 were significantly superior to those of the film of Comparative Example 1 in all indicators. Compared to the film of Comparative Example 1, the tensile strength of the film obtained from the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane of Example 1 was 13 times that of the film of Comparative Example 1, and the toughness was 43 times that of the film of Comparative Example 1. Specifically, with the increase of lactobionic acid content, the elongation at break and toughness of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane films decreased, while the tensile strength increased, with the highest tensile strength reaching over 40 MPa. The excellent mechanical properties are attributed to the nanocluster structure formed by the self-assembly of hydroxyl and carboxyl groups of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane through intermolecular hydrogen bonding during the film formation process. This in-situ phase-separated structure can dissipate energy through structural dissociation during the stretching process, thereby achieving the effect of enhancing toughness.

[0062] Experimental Example 5

[0063] In this experimental example, the self-healing performance of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane films of Examples 1-3 and the vegetable oil-based waterborne polyurethane film of Comparative Example 1 was tested.

[0064] Test method: Use a blade to cut a wound of about 5 μm on the film, then spray ethanol on the wound, and finally place the film under an optical electron microscope to observe the self-healing state of the film wound.

[0065] Figure 5 The wound healing performance of the antibacterial, self-toughening, self-healing, recyclable plant oil-based waterborne polyurethane films of Examples 1-3 and the plant oil-based waterborne polyurethane film obtained in Comparative Example 1 after being treated with ethanol is shown respectively. Figure 5It can be observed that the plant oil-based waterborne polyurethane film of comparative example 1 has a reduced material wound width under the stimulation of ethanol, but ultimately cannot achieve complete healing. In contrast, the antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethane films of Examples 1-3 show a process in which wounds are clearly visible, wound interface adhesion, and wound surface complete healing within 15 minutes after ethanol treatment. Specifically, the wound of the antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethane film of Example 1 is completely healed after ethanol treatment for 9 minutes, the wound of the antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethane film of Example 2 is completely healed after ethanol treatment for 12 minutes, and the wound of the antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethane film of Example 3 is completely healed after ethanol treatment for 15 minutes, indicating that as the content of lactobionic acid increases, the wound healing time of the antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethane film also increases, which may be related to the compactness of the internal structure of the polyurethane. Thus, the present invention has discovered that ethanol, a liquid small molecule solvent rich in hydrogen bond donors and acceptors, has the effect of promoting rapid wound healing of antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethane films. This is because, compared with plant oil-based waterborne polyurethane films that lack hydrogen bond self-assembled nanoclusters, the antibacterial, self-toughening, self-healing, and recyclable plant oil-based waterborne polyurethane films of Examples 1-3 form nanoclusters in ethanol through self-assembly through intermolecular hydrogen bonding to achieve self-healing of wounds. At this time, hydrogen bonds serve as a unique non-covalent dynamic bond that gives the film excellent self-healing properties.

[0066] Experimental Example 6

[0067] In this experimental example, the recyclability performance of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film of Example 1 and the vegetable oil-based waterborne polyurethane film of Comparative Example 1 was tested.

[0068] The vegetable oil-based waterborne polyurethane film of Comparative Example 1 was cut into fragments, and then the fragments were hot pressed at 140°C and 20 MPa. It was found that the vegetable oil-based waterborne polyurethane film was difficult to recover from the fragment state into a complete film by hot pressing.

[0069] The antibacterial, self-toughening, self-healing, recyclable plant oil-based waterborne polyurethane film of Example 1 was cut into pieces, and then the pieces were hot pressed under the conditions of 140°C and 20 MPa, and the above process was repeated 5 times. The recyclability test results of the antibacterial, self-toughening, self-healing, recyclable plant oil-based waterborne polyurethane film of Example 1 are shown in FIG. Figure 6It can be observed that the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film of Example 1 can be transformed from a debris state into a complete film through hot pressing, indicating that the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film of Example 1 has better recyclability than the film of Comparative Example 1. After five repeated shearing and hot pressing, the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film of Example 1 can still maintain its original state. This shows that the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film with hydrogen-bonded self-assembled nanoclusters can still recover its original state through the dissociation and recombination of hydrogen bonds after multiple shearing and hot pressing, showing excellent multiple recycling potential. Therefore, the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film of the present invention can solve the problem of the difficulty of recycling and reusing thermosetting materials and extend the service life of thermosetting polyurethane materials.

[0070] Experimental Example 7

[0071] In this experimental example, the antibacterial properties of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film of Example 1 and the vegetable oil-based waterborne polyurethane film of Comparative Example 1 were tested.

[0072] Test method: The antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film of Example 1 and the vegetable oil-based waterborne polyurethane film of Comparative Example 1 were irradiated with 365 nm ultraviolet light for 30 minutes, and then soaked in a PBS solution with a pH of 7 for 30 minutes and set aside. The films were co-incubated with 1 mL of Staphylococcus aureus culture and 1 mL of Escherichia coli culture (culture concentration of 0.5 McFarland turbidity) for 3.5 hours, filtered, and 30 μL of the culture was evenly spread on the agar surface. The films were then incubated in a 37°C incubator for 16 hours to observe bacterial growth.

[0073] Antibacterial performance test results are as follows Figure 7 As shown. Figure 7It can be seen that bacterial strains still grow on the agar surface treated with the vegetable oil-based waterborne polyurethane film of Comparative Example 1, indicating that the antibacterial effect of the vegetable oil-based waterborne polyurethane film against Escherichia coli and Staphylococcus aureus is relatively weak. This may be due to the volatilization of acetic acid during the drying and film-forming process of the vegetable oil-based waterborne polyurethane, which causes the dissociation of quaternary ammonium ion pairs within the material. No bacterial strains are observed on the agar surface treated with the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film of Example 1, indicating that the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film exhibits excellent antibacterial effects against Escherichia coli and Staphylococcus aureus. This is attributed to the large number of quaternary ammonium ion pairs contained in the nanoclusters of the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane film of Example 1, which have excellent antibacterial effects against Escherichia coli and Staphylococcus aureus.

[0074] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. Antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane, characterized in that: The system is prepared from the following raw materials, calculated in parts by weight: 200-400 parts of castor oil, 100-300 parts of dicyclohexylmethane diisocyanate, 70-150 parts of hexamethylene diisocyanate, 70-150 parts of N-methyldiethanolamine, 100-400 parts of lactobionic acid, 7000-10000 parts of water, and 5-15 parts of a catalyst; The method for preparing the antibacterial, self-toughening, self-healing, and recyclable vegetable oil-based waterborne polyurethane comprises the following steps: S1. reacting dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and N-methyldiethanolamine at 80-85° C. for 0.5-2 h to obtain a prepolymer; S2. Add castor oil to the prepolymer and react for 1.5-2 hours to obtain a reaction system; S3, adding a catalyst to the reaction system, and reacting until the reaction system no longer has fluidity; S4, adding an organic solvent to the reaction system, reacting for 1.5-2 hours, and cooling to room temperature to obtain a polyurethane solution system; S5. Dissolve lactobionic acid in water to obtain an aqueous solution of lactobionic acid, add the aqueous solution of lactobionic acid to the polyurethane solution system, emulsify, and then remove the organic solvent by rotary evaporation to obtain.

2. The antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane according to claim 1, characterized in that: The molar ratio of lactobionic acid to N-methyldiethanolamine is 0.6:1-1.1:

1.

3. The antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane according to claim 1, characterized in that: The catalyst is selected from at least one of dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin dioctoate.

4. The antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane according to claim 1, characterized in that: The antibacterial, self-toughening, self-healing and recyclable vegetable oil-based waterborne polyurethane has a solid content of 10%-30%.

5. The method for preparing the antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. reacting dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and N-methyldiethanolamine at 80-85° C. for 0.5-2 h to obtain a prepolymer; S2. Add castor oil to the prepolymer and react for 1.5-2 hours to obtain a reaction system; S3, adding a catalyst to the reaction system, and reacting until the reaction system no longer has fluidity; S4, adding an organic solvent to the reaction system, reacting for 1.5-2 hours, and cooling to room temperature to obtain a polyurethane solution system; S5. Dissolve lactobionic acid in water to obtain an aqueous solution of lactobionic acid, add the aqueous solution of lactobionic acid to the polyurethane solution system, emulsify, and then remove the organic solvent by rotary evaporation to obtain.

6. The method for preparing the antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane according to claim 5, characterized in that: In step S4, the organic solvent is selected from at least one of acetone and butanone; the amount of the organic solvent is 20-40 mL.

7. The method for preparing the antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane according to claim 5, characterized in that: In step S5, the rotation speed used for emulsification is 800-1000 r / min, and the emulsification time is 1-2 h.

8. Use of the antibacterial, self-toughening, self-healing, recyclable vegetable oil-based waterborne polyurethane according to any one of claims 1 to 4 in the preparation of coatings, antibacterial materials, and adhesives.

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