A comb-like sulfonated lignin waterborne polyurethane, and a preparation method and application thereof

Abstract

The application discloses a kind of comb sulfonated lignin water-based polyurethane and its preparation method and application, the resin is mainly made by the following weight parts of raw materials by polycondensation reaction: 3-50 parts diisocyanate, 5-45 parts polyglycol, 2-35 parts modified zwitterionic monomer, 2-10 parts hydroxyethyl disulfide, 5-20 parts sulfonated modified lignin, 0.1-2 parts catalyst and 50-150 parts deionized water.The polyurethane resin prepared by the application has excellent coating film mechanical properties, super elasticity and a lighter surface color;When the resin is used for fabric coating or printing, it can give the fabric self-repairing, ultraviolet resistance and antibacterial properties, etc.The preparation process of the application is green and environmentally friendly, and the prepared polyurethane can be applied in the fields of fabric, leather, automotive interior, wood, etc.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane preparation, and in particular to a comb-shaped sulfonated lignin waterborne polyurethane and a preparation method and application thereof. Background Art

[0002] Conventional polyester waterborne polyurethanes suffer from poor water resistance and mechanical properties. Using grafting or block chain extenders and blending them to form a crosslinked network can mitigate these shortcomings and broaden their applications. The introduction of phosphorylcholine groups enhances microphase separation and forms denser hydrogen bonds within uniformly sized hard segments. The resulting films exhibit excellent tensile properties and slow hydrolytic degradation rates, while also exhibiting excellent low-temperature flexibility, low surface tension, and weather resistance. Combining these with polyurethanes can effectively improve their flexibility and biocompatibility. Furthermore, research on biomass materials derived from plant and animal resources is currently active. Biomass is renewable, widely available, and inexpensive. Incorporating biomass monomers into polyurethane materials can not only improve the mechanical properties, water resistance, and biodegradability of polyurethanes, but also combine the environmental and biodegradability advantages of natural materials. There is a pressing need to find methods that can protect resins from UV radiation for extended periods and enhance their stability. Therefore, the introduction of specialized functional monomers into polyurethanes can also enhance the durability of polyurethanes used in textiles and expand their applications.

[0003] In the existing preparation of bio-based waterborne polyurethanes, bio-based monomers are often directly introduced into polyurethanes. The bio-based waterborne polyurethanes obtained in this way can have the following functions: good thermal stability, good room temperature biodegradability, and can also increase the solid content of the waterborne polyurethane. However, after the bio-based waterborne polyurethanes in the prior art are applied to substrates such as fabrics or leather, they will be affected by ultraviolet rays, and the mechanical properties are not ideal. Patent CN202310540644.9 discloses a method for preparing a lignin-based polyurethane elastomer, which is prepared from polyether polyols, modified lignin, a catalyst and isocyanate. The tensile strength and elongation at break of the elastomer are increased, but the mechanical properties are still not ideal, and the resin is solvent-based. Patent CN202211369453.2 reports a lignin-based waterborne polyurethane emulsion, which consists of lignin, oligomer polyols, polyisocyanates, hydrophilic chain extenders, polyol compounds, organic solvents, etc. Compared with the prior art, the lignin-based waterborne polyurethane emulsion has functional properties such as stability, low cost, green environmental protection, high mechanics, UV resistance, antibacterial, and hydrophobicity, and also realizes the high value utilization of lignin as a renewable resource. Although the mechanical properties of the emulsion coating prepared by the above method have been improved, the mechanical properties of the coating are not good enough, and because it does not have a self-repairing function, the service life of the coating will be affected after experiencing the lasting action of external force. SUMMARY

[0004] The present application provides a comb-shaped sulfonated lignin waterborne polyurethane, which improves the mechanical properties and self-repairing properties of bio-based waterborne polyurethane, and can impart the fabric with properties such as ultraviolet resistance and antibacterial resistance when applied to the surface of the fabric, thereby solving the problems of deep color and durability of lignin-based fabric coatings.

[0005] The present application also provides a preparation method and application of the comb-shaped sulfonated lignin waterborne polyurethane.

[0006] The present application provides a comb-shaped sulfonated lignin waterborne polyurethane, which comprises the following raw materials by weight: 3-50 parts of diisocyanate, 5-45 parts of polyglycol, 2-35 parts of modified zwitterionic monomer, 2-10 parts of 2-hydroxyethyl disulfide, 5-20 parts of sulfonated lignin, 0.1-2 parts of catalyst, and 50-150 parts of deionized water.

[0007] The diisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0008] The polyglycol is one or more of polyethylene glycol, polypropylene glycol, polycaprolactone glycol, and polytetrahydrofuran glycol.

[0009] Preferably, the molecular weight of the polyglycol is 600-4000.

[0010] The catalyst is one or more of N,N-dimethylcyclohexylamine, N,N'-dimethylpyridine, stannous octoate, and dibutyltin dilaurate.

[0011] The preparation steps of the modified zwitterionic monomer are as follows:

[0012] The modified zwitterionic monomer is obtained by mixing 0.5-10 parts of mercaptan glycol monomer, 0.5-10 parts of zwitterionic monomer, 0.1-0.5 parts of azobis isovaleronitrile, and 5-20 parts of acetone uniformly and then reacting at 40-80℃ for 1-6 hours; the zwitterionic monomer is one or more of methacryloyl ethyl betaine, 1-vinyl-3-(propyl sulfonic acid) imidazole inner salt, 2-methacryloyloxyethyl phosphocholine, and 1-(2-methyl) acryloyl-3-(propyl sulfonic acid) imidazole inner salt; and the mercaptan glycol monomer is one or more of 3-mercapto-1,2-propanediol and dithioerythritol.

[0013] The preparation steps of the sulfonated lignin are as follows:

[0014] The sulfonated modified lignin is obtained by uniformly mixing 2-20 parts of lignin monomers, 5-30 parts of sulfonic acid lactone, 1-5 parts of sodium hydroxide and 20-50 parts of acetone, and then reacting at 60-90 DEG C for 1-3 hours; the lignin monomers are one or more of alkali lignin and dealkalized lignin; the sulfonic acid lactone is one or more of 1, 4-butyric sulfonic acid lactone and 1, 3-propyl sulfonic acid lactone.

[0015] The preparation method of the comb-shaped sulfonated lignin water-based polyurethane comprises the following steps:

[0016] The diisocyanate, the polyhydric alcohol and the catalyst are added into acetone and uniformly mixed, then inert gas is introduced, and then the system is heated, then the modified zwitterionic monomer and 2-hydroxyethyl disulfide are added into the system for further heating reaction, then the sulfonated lignin is added into the system for heating reaction, finally the temperature of the system is reduced, then deionized water is added into the system and uniformly mixed to obtain the sulfonated modified biomass-based water-based polyurethane.

[0017] The diisocyanate, the polyhydric alcohol and the catalyst are added into acetone and uniformly mixed, then inert gas is introduced, and then the system is heated, then the modified zwitterionic monomer and 2-hydroxyethyl disulfide are added into the system for further heating reaction, then the sulfonated lignin is added into the system for heating reaction, finally the temperature of the system is reduced, then deionized water is added into the system and uniformly mixed to obtain the sulfonated modified biomass-based water-based polyurethane.

[0018] The comb-shaped sulfonated lignin water-based polyurethane is applied in the fields of fabrics, leathers, automotive interiors and wood.

[0019] The comb-shaped sulfonated lignin water-based polyurethane can be coated on the surface of a substrate by dipping, roller coating, spraying and printing, and dried at 40-80 DEG C to form a film.

[0020] Further, the polyurethane forms a film with a thickness of 40-200 microns.

[0021] In the present application, the prepared modified zwitterionic monomer can be successfully connected to the polyurethane, increase the molecular weight of the polyurethane, and the introduced zwitterion can be nucleophilically substituted or covalently combined with the hydroxyl group on the textile or leather (i.e. form ionic bonds), thereby improving the adhesion of the coating film on the surface of the textile or leather and imparting good water washing fastness. On the other hand, based on the side chain zwitterionic characteristics, the tensile strength and self-repairing efficiency of the polyurethane coating film can be improved.

[0022] Further, in the method for preparing the sulfonated lignin in the present application, the sulfonation reaction occurs between the phenolic hydroxyl group bank in the lignin molecule and the sulfonic acid lactone, so that the sulfonic acid lactone is connected to the molecule, and further expanded into the polyurethane, which not only improves the hydrophilicity of the polyurethane, but also gives the fabric or leather excellent UV resistance and antibacterial effect when the water-based polyurethane is applied to the textile or leather.

[0023] The present application can improve the flexibility, biocompatibility and antibacterial performance of the polyurethane by introducing the modified zwitterionic monomer. The introduction of the phosphocholine group enhances the microphase separation degree and improves the hydrolytic degradation of the film, and forms more compact hydrogen bonds in the uniform size hard segment, so that the film exhibits good tensile properties and slow hydrolytic degradation rate; meanwhile, it also satisfies the characteristics of full and comfortable hand feeling. The access of hydroxyethyl disulfide makes the modified polyurethane have good self-repairing performance. By adding sulfonated lignin, lignin is a biological material, green and environmentally friendly, which improves the hydrophilic performance of the polyurethane and makes the polyurethane have ultraviolet resistance and antibacterial function. Therefore, by matching the specific preparation method of the present application and the adding sequence of each formula, a biomass-based water-based polyurethane with high tensile strength and ultraviolet resistance can be prepared, and the flexibility and ultraviolet resistance function meet the requirements of subsequent application in textiles and leather. Here, it is important to note that the preparation sequence of the present application cannot be changed, because the sulfonated lignin has multiple hydroxyl groups, so it should be added after the modified zwitterionic monomer is introduced into the polyurethane prepolymer, so as to cap the isocyanate groups in the polyurethane chain. If the above preparation sequence is changed, the disulfide and zwitterionic monomer cannot be completely introduced, which affects the self-repairing and antibacterial performance. The sulfonated lignin in the present application solves the problem of too dark color of the film caused by the original lignin, while retaining the ultraviolet resistance and antibacterial performance; the introduction of disulfide gives the self-repairing performance and increases the durability of the coating.

[0024] In the present application, the zwitterionic monomer is modified by mercaptan diol, and then the modified zwitterionic monomer, disulfide and sulfonated lignin are introduced into the polyurethane prepolymer in sequence to obtain a biomass-based water-based polyurethane. The polyurethane prepared by the present application has excellent mechanical properties, super elasticity and a relatively light surface color; when the resin is used for fabric coating or printing, it can give the fabric self-repairing, ultraviolet resistance and antibacterial properties. The preparation process of the present application is green and environmentally friendly, and the prepared polyurethane can be applied in the fields of fabric, leather, automotive interior, wood, etc.

[0025] Advantages: Compared with the prior art, the present application has the following advantages:

[0026] (1) The biomass-based water-based polyurethane prepared by the present application is based on zwitterionic monomer and lignin, and the polyurethane has a comb structure, excellent mechanical properties, super elasticity and a relatively light surface color;

[0027] (2) The polyurethane is biomass and biodegradable;

[0028] (3) The polyurethane can be applied to the surface of substrates such as fabrics, leather, etc. and endows them with excellent ultraviolet resistance and antibacterial properties;

[0029] (4) The polyurethane has a simple preparation process, and water as a solvent is green and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A schematic flow chart of the preparation method of the phosphocholine monomer grafted waterborne polyurethane in the present application;

[0031] Figure 2 An infrared spectrogram of the waterborne polyurethane of the present application;

[0032] Figure 3 A nuclear magnetic hydrogen spectrogram of the waterborne polyurethane of the present application;

[0033] Figure 4 The healing effect of the waterborne polyurethane of the present application;

[0034] Figure 5 The self-repairing process diagram of the polyurethane film in the present application under scratch and cut conditions;

[0035] Figure 6 The ultraviolet absorption spectrogram of the coated fabric under different lignin contents in the present application;

[0036] Figure 7 The ultraviolet protection index diagram of the coated fabric under different lignin contents in the present application;

[0037] Figure 8 The bacterial culture diagram of the polyurethane coated fabric surface in the present application. DETAILED DESCRIPTION

[0038] The present application is further described below in combination with examples.

[0039] The experimental methods described in the examples are all conventional methods unless otherwise specified; and the reagents and materials described are all commercially available unless otherwise specified.

[0040] Example 1

[0041] Prepare the sulfonated modified biomass-based waterborne polyurethane according to parts by weight, as shown in Figure 1

[0042] ​(1) 10 parts of 2-methacryloyloxyethyl phosphorylcholine, 10 parts of 3-mercapto-1,2-propanediol, 0.5 parts of azobisisovaleronitrile and 20 parts of acetone were mixed uniformly, and then reacted at 80°C for 6 hours to obtain the modified phosphorylcholine.

[0043] (2) 5 parts of alkaline lignin (alkali lignin, cas: 8068-05-1, macron L832292), 20 parts of 1,4-butanesultone, 5 parts of sodium hydroxide and 50 parts of acetone were mixed uniformly, and then reacted at 90°C for 3 hours to obtain sulfonated lignin.

[0044] (3) First, 20 parts of polytetrahydrofuran ether diol (molecular weight 400), 45 parts of hexamethylene diisocyanate, 2 parts of dibutyltin dilaurate and 100 parts of acetone were mixed uniformly, then purged with high-purity nitrogen for 30 minutes, and then reacted at 80°C for 3 hours to obtain a prepolymer; 10 parts of modified phosphorylcholine monomer and 8 parts of 2-hydroxyethyl disulfide were added to the above prepolymer, and the reaction was continued at 80°C for 3 hours; then 5 parts of sulfonated lignin was added to the prepolymer, and the reaction was continued at 80°C for 5 hours; finally, the temperature of the system was reduced to below 40°C, and then 150 parts of deionized water was added to the system and mixed uniformly to obtain a sulfonated modified biomass-based waterborne polyurethane.

[0045] (4) The above biomass-based waterborne polyurethane was coated on the surface of a cotton fabric by brushing, and then dried at 80°C to obtain a polyurethane coated fabric, with a coating film thickness of 200 μm.

[0046] The infrared spectrum and the nuclear magnetic hydrogen spectrum of the waterborne polyurethane prepared in this example are shown in Figures Figure 2 and Figure 3 respectively. In the prepolymer, an excess of -NCO infrared peak was observed at 2260 cm -1 , and no obvious absorption peak was observed in the polymer, indicating that -NCO was consumed by -OH monomer and formed an elastomer. The absorption peaks at about 2935 cm -1 and 2862 cm -1 are attributed to the vibration of methyl and methylene groups. The absorption peaks at 3310 cm -1 and 1729 cm -1 correspond to the stretching vibration of -N-H bond and the stretching vibration of carbonyl group in isocyanate. In addition, the infrared peak at 1380 cm -1 corresponds to the aromatic vibration of lignin, and the infrared peak at 1246 cm -1The peaks at 3.79 ppm and 1.64 ppm correspond to -CH2 units near ether linkages and carbonyl groups in the soft segment, while the signal at 3.30 ppm corresponds to the terminal CH2-OH of the soft segment. The proton signals at 2.93 ppm and 1.39 ppm are mainly related to alkyl groups in the hard segment units. The proton signal at 4.0 ppm confirms the formation of the polyurethane linkage. The proton signals in the range of 0.89 to 1.39 ppm correspond to -CH3, -CH and N+-CH3, respectively. In addition, the proton signals of the terminal sulfonated lignin were also observed at 8.0 ppm, 2.78 ppm and 0.93 ppm. The chemical structure of the polyurethane was confirmed by1H NMR and FT-IR, indicating that the polyurethane was successfully synthesized.

[0047] The following control of the preparation of zwitterionic monomer and sulfonated lignin is the same as Example 1:

[0048] The preparation method of the control sample polyurethane 1 (only without zwitterionic monomer and sulfonated lignin compared with Example 1): First: 20 parts of polytetrahydrofuran ether diol (molecular weight 400), 45 parts of hexamethylene diisocyanate, 2 parts of dibutyltin dilaurate and 100 parts of acetone are uniformly mixed, then purged with high-purity nitrogen for 30 minutes, and then reacted at 80°C for 3 hours to obtain a prepolymer; 8 parts of 2-hydroxyethyl disulfide are added to the above prepolymer, and the system is continuously reacted at 80°C for 8 hours, and finally the temperature of the system is reduced to below 40°C, then 150 parts of deionized water is added to the system and mixed uniformly to obtain a biomass-based waterborne polyurethane. The above waterborne polyurethane is coated on the surface of the cotton fabric by brushing, and is dried at 80°C to obtain a polyurethane coated fabric, and the coating film thickness is 200 μm.

[0049] The preparation method of the control sample polyurethane 2 (only without zwitterionic monomer compared with Example 1): First: 20 parts of polytetrahydrofuran ether diol (molecular weight 400), 45 parts of hexamethylene diisocyanate, 2 parts of dibutyltin dilaurate and 100 parts of acetone are uniformly mixed, then purged with high-purity nitrogen for 30 minutes, and then reacted at 80°C for 3 hours to obtain a prepolymer; 8 parts of 2-hydroxyethyl disulfide are added to the above prepolymer, and the system is continuously reacted at 80°C for 3 hours, then 5 parts of sulfonated lignin is added to the prepolymer and the system is continuously reacted at 80°C for 5 hours, and finally the temperature of the system is reduced to below 40°C, then 150 parts of deionized water is added to the system and mixed uniformly to obtain a biomass-based waterborne polyurethane. The above waterborne polyurethane is coated on the surface of the cotton fabric by brushing, and is dried at 80°C to obtain a polyurethane coated fabric, and the coating film thickness is 200 μm.

[0050] The preparation method of the control sample polyurethane 3 (only without sulfonated lignin compared with Example 1): first, 20 parts of polytetrahydrofuran ether diol (molecular weight 400), 45 parts of hexamethylene diisocyanate, 2 parts of dibutyl tin dilaurate and 100 parts of acetone are uniformly mixed, then purged with high-purity nitrogen for 30 minutes, and then reacted at 80°C for 3 hours to obtain a prepolymer; 10 parts of modified phosphocholine monomer and 8 parts of 2-hydroxyethyl disulfide are added to the above-mentioned prepolymer, and the system is continuously reacted at 80°C for 8 hours, and finally the temperature of the system is reduced to below 40°C, then 150 parts of deionized water is added to the system and uniformly mixed to obtain a biomass-based waterborne polyurethane. The above-mentioned waterborne polyurethane is coated on the surface of the cotton fabric by brushing, and is dried at 80°C to obtain a polyurethane coated fabric, and the coating film thickness is 200μm.

[0051] The preparation method of the control sample polyurethane 4 (only adding sulfonated lignin first and then adding modified zwitterion compared with Example 1): first, 20 parts of polytetrahydrofuran ether diol (molecular weight 400), 45 parts of hexamethylene diisocyanate, 2 parts of dibutyl tin dilaurate and 100 parts of acetone are uniformly mixed, then purged with high-purity nitrogen for 30 minutes, and then reacted at 80°C for 3 hours to obtain a prepolymer; 5 parts of modified sulfonated lignin monomer and 8 parts of 2-hydroxyethyl disulfide are added to the above-mentioned prepolymer, and the system is continuously reacted at 80°C for 3 hours, then 8 parts of modified phosphocholine monomer is added and reacted at 80°C for 5 hours, finally the temperature of the system is reduced to below 40°C, then 150 parts of deionized water is added to the system and uniformly mixed to obtain a biomass-based waterborne polyurethane. The above-mentioned waterborne polyurethane is coated on the surface of the cotton fabric by brushing, and is dried at 80°C to obtain a polyurethane coated fabric, and the coating film thickness is 200μm.

[0052] Example 2

[0053] (1) 1.2 parts of methacryloyl ethyl betaine, 3 parts of dithioerythritol, 0.3 parts of azobis isovaleronitrile and 12 parts of acetone are uniformly mixed, and then reacted at 65°C for 3 hours to obtain modified betaine.

[0054] (2) 12 parts of alkali lignin (lignin (dealkalized), cas: 9005-53-2, Aldrich L195713), 22 parts of 1,3-propanesultone, 3 parts of sodium hydroxide and 25 parts of acetone are uniformly mixed, and then reacted at 75°C for 2 hours to obtain sulfonated lignin.

[0055] (3) First, 25 parts of polycaprolactone diol (molecular weight 2000), 13 parts of isophorone diisocyanate, 1.1 parts of stannous octoate and 60 parts of acetone were mixed uniformly, then high-purity nitrogen was blown for 30 minutes, and then the pre-polymer was obtained by reacting at 65°C for 2 hours; 5.5 parts of modified betaine monomer and 4.5 parts of hydroxyethyl disulfide were added to the above pre-polymer, and after continuing to react at 65°C for 2 hours, 4 parts of sulfonated lignin was added to the pre-polymer and continued to react at 65°C for 3 hours, and finally the temperature of the system was reduced to below 40°C, then 110 parts of deionized water was added to the system and mixed uniformly to obtain a sulfonated modified biomass-based waterborne polyurethane.

[0056] (4) The above biomass-based waterborne polyurethane was coated on the surface of the cotton fabric by spraying, and was dried at 60°C to obtain a polyurethane coated fabric, and the coating film thickness was 100 μm.

[0057] Example 3

[0058] (1) 0.5 parts of 1-vinyl-3-(propanesulfonic acid) imidazole inner salt, 0.5 parts of 3-mercapto-1,2-propanediol, 0.1 parts of azobis isovaleronitrile and 5 parts of acetone were mixed uniformly, and then the modified imidazole salt was obtained by reacting at 40°C for 1 hour.

[0059] (2) 2 parts of alkali lignin, 5 parts of 1,4-butanesultone and 1 part of sodium hydroxide were mixed uniformly with 20 parts of acetone, and then the sulfonated lignin was obtained by reacting at 60°C for 1 hour.

[0060] (3) First, 5 parts of polyethylene glycol (molecular weight 4000), 3 parts of diphenyl methane diisocyanate, 0.1 parts of N,N'-dimethylpyridine and 30 parts of acetone were mixed uniformly, then high-purity nitrogen was blown for 30 minutes, and then the pre-polymer was obtained by reacting at 40°C for 1 hour; 2 parts of modified imidazole salt monomer and 2 parts of hydroxyethyl disulfide were added to the above pre-polymer, and after continuing to react for 1 hour, 5 parts of sulfonated lignin was added to the pre-polymer and continued to react for 2 hours, and finally the temperature of the system was reduced to below 40°C, then 50 parts of deionized water was added to the system to obtain a sulfonated modified biomass-based waterborne polyurethane.

[0061] (4) The above biomass-based waterborne polyurethane was coated on the surface of the cotton fabric by spraying, and was dried at 40°C to obtain a polyurethane coated fabric, and the coating film thickness was 40 μm.

[0062] Example 4

[0063] (1) 0.8 parts of 1-(2-methyl) acryloyl-3-(propanesulfonic acid) imidazole inner salt, 1 part of dithioerythritol, 0.2 parts of azobis isovaleronitrile and 8 parts of acetone were mixed uniformly, and then the modified imidazole inner salt was obtained by reacting at 50°C for 2 hours.

[0064] (2) 8 parts of the de-alkali lignin, 10 parts of 1,3-propane sultone, 2 parts of sodium hydroxide and 30 parts of acetone were mixed uniformly, and then reacted at 70 °C for 2 hours to obtain the sulfonated lignin.

[0065] (3) First, 5 parts of polypropylene glycol (molecular weight 800), 3 parts of toluene diisocyanate, 0.1 parts of N,N-dimethylcyclohexylamine and 30 parts of acetone were mixed uniformly, then purged with high-purity nitrogen for 30 minutes, and then reacted at 40 °C for 1 hour to obtain a prepolymer; 3 parts of modified imidazole inner salt monomer and 3.5 parts of hydroxyethyl disulfide were added to the above prepolymer, and the reaction was continued for 2 hours, then 8 parts of sulfonated lignin was added to the prepolymer and the reaction was continued for 3 hours, and finally the temperature of the system was reduced to below 40 °C, then 70 parts of deionized water was added to the system to obtain a sulfonated modified biomass-based waterborne polyurethane.

[0066] (4) The above biomass-based waterborne polyurethane was coated on the surface of the cotton fabric by printing, and then dried at 50 °C to obtain a polyurethane coated fabric, and the coating film thickness was 80 μm.

[0067] Example 5

[0068] (1) 1.5 parts of methacryloyloxyethyl phosphocholine, 4 parts of dithioerythritol, 0.4 parts of azobis isovaleronitrile and 15 parts of acetone were mixed uniformly, and then reacted at 70 °C for 5 hours to obtain modified phosphocholine.

[0069] (2) 15 parts of alkali lignin, 23 parts of 1,4-butane sultone, 3.5 parts of sodium hydroxide and 45 parts of acetone were mixed uniformly, and then reacted at 80 °C for 2 hours to obtain sulfonated lignin.

[0070] (3) First, 40 parts of polycaprolactone diol (molecular weight 1000), 16 parts of isophorone diisocyanate, 1.5 parts of dibutyltin dilaurate and 80 parts of acetone were mixed uniformly, then purged with high-purity nitrogen for 30 minutes, and then reacted at 70 °C for 2 hours to obtain a prepolymer; 8 parts of modified phosphocholine monomer and 7 parts of hydroxyethyl disulfide were added to the above prepolymer, and the reaction was continued for 2 hours, then 15 parts of sulfonated lignin was added to the prepolymer and the reaction was continued for 4 hours, and finally the temperature of the system was reduced to below 40 °C, then 120 parts of deionized water was added to the system to obtain a sulfonated modified biomass-based waterborne polyurethane.

[0071] (4) The above biomass-based waterborne polyurethane was coated on the surface of the cotton fabric by printing, and then dried at 70 °C to obtain a polyurethane coated fabric, and the coating film thickness was 160 μm.

[0072] Example 6

[0073] The tensile test of the biomass-based waterborne polyurethane was performed by using a universal testing machine. The mechanical properties of the polyurethane elastomer were tested and analyzed by using a microcomputer-controlled electronic universal testing machine. Specifically, the waterborne polyurethane prepared in Examples 1-5 was poured into a dumbbell-shaped polytetrafluoroethylene mold and placed in an 80°C oven for heat baking for 6h to obtain the polyurethane elastomer. The tensile rate of the testing machine was set to 200mm / min. The mechanical properties of the polyurethane elastomer prepared in Examples 1-5 and the polyurethane elastomer of Comparative Examples 1-4 were determined, and the results are shown in Table 1.

[0074] Table 1 Mechanical properties of polyurethane elastomer

[0075] Tensile strength (MPa) Elongation at break (%) Example 1 56.8 834 Example 2 43.7 688 Example 3 41.9 597 Example 4 55.9 625 Example 5 54.8 601 Control 1 5.9 125 Control 2 30.5 476 Control 3 34.2 524 Control 4 40.5 574

[0076] As can be seen from Table 1, compared with the polyurethane of the comparative example, the mechanical properties of the polyurethane film of the present application are superior, and the tensile strength and elongation at break are far superior to the comparative polyurethane. This is mainly because of the interaction between the polyurethane comb structure and the zwitterion and the hydrogen bonding force provided by the lignin, among which the specific positive and negative ion interaction force and the comb structure can help the force to maximize; at the same time, a large number of hydrogen bonds have a synergistic effect. As can be seen from the above comparative examples, the mechanical properties of the present application without adding zwitterionic monomer and sulfonated lignin will be significantly reduced, indicating that the two have a synergistic effect in the system. In addition, the zwitterionic monomer must be added first and then the sulfonated lignin during preparation. If the order of addition is changed, the sulfonated lignin with a large number of hydroxyl groups will react with all the isocyanate groups, and the zwitterionic monomer will not be able to enter, which will also affect the effect to some extent.

[0077] In addition, in the present application, biomass material lignin and zwitterionic monomer are introduced into polyurethane; while in Example 1, if DMBA is used instead of sulfonated lignin to cap, the mechanical properties of the elastomer will be significantly reduced (tensile strength 12.1MPa, elongation at break 280%). Or replace 2-hydroxyethyl disulfide in Example 1, the self-repairing effect of the film is also significantly reduced. The polyurethane prepared in Example 1 is as follows Figure 4 a, showing a gradual and obvious healing effect, reaching 29% and 63% repair rates after 1 hour and 2 hours at room temperature, respectively. In contrast, under the same conditions, replacing 2-hydroxyethyl disulfide shows a smaller repair effect Figure 4 b).

[0078] Example 7

[0079] The polyurethane film prepared in Example 1 was tested, and an optical microscope was used to record the morphology change of the scratch during the self-repairing process of the PU coating, and the magnification of the objective lens and the eyepiece was ×10, ×10, respectively. Figure 5As shown, the polyurethane synthesized in Example 4 has self-repairing ability, no matter being scratched or cut, the coating film can complete repair within 4 minutes at 60℃, which is mainly due to the dynamic reversible assembly of ionic bonds and disulfide bonds between zwitterions.

[0080] Example 8

[0081] According to the preparation method of Example 1, the UPF value and ultraviolet protection index of the coated fabric under different lignin content were determined by using the cotton fabric ultraviolet transmittance tester according to AATCC 183-2020 standard, and the UPF value and ultraviolet protection index of the coated fabric were determined by Figure 6 and Figure 7 It can be found that when the content of sulfonated lignin in the system reaches 6% and above, the ultraviolet protection index (UPF) of the fabric coating can reach more than 50, even more than 100, indicating that the polyurethane coated fabric of this content has good ultraviolet resistance.

[0082] Example 9

[0083] The antibacterial performance test was carried out on the polyurethane film prepared in Example 1, and the shake flask method was used to evaluate the antibacterial effect of water-based polyurethane film on S. aureus and E. coli. All samples were set up with 3 parallel control samples, and the antibacterial performance of all samples was detected according to GB / T 20944.3-2008. As Figure 8 shown, the polyurethane coated fabric in Example 3 has excellent antibacterial performance, while the control sample surface has many S. aureus and E. coli, which is mainly due to the presence of zwitterions and lignin in the coating.

[0084] Example 10

[0085] The two branched, multiply branched structures in the polyurethane macromolecular chain, the charge attraction between positive and negative ions makes it comb-like orderly distribution. Through K / S value test, the color of the film capped with modified sulfonated lignin is lighter, which has good application prospect on fabric. By comparing Examples 1-4, the polyurethane with the best performance is Example 1.

[0086]

Claims

1. A comb-like sulfonated lignin aqueous polyurethane, characterized in that, The raw materials include the following weight parts: 3-50 parts of diisocyanate, 5-45 parts of polyglycol, 2-35 parts of modified zwitterionic monomer, 2-10 parts of 2-hydroxyethyl disulfide, 5-20 parts of sulfonated lignin, 0.1-2 parts of catalyst and 50-150 parts of deionized water; The preparation steps of the modified zwitterionic monomer are as follows: The modified zwitterionic monomer is obtained by uniformly mixing 0.5-10 parts of mercaptan glycol monomer, 0.5-10 parts of zwitterionic monomer, 0.1-0.5 parts of azobis diisopentyl cyanide and 5-20 parts of acetone, and then reacting at 40-80℃ for 1-6 hours; the zwitterionic monomer is one or more of methacryloyl ethyl betaine, 1-vinyl-3-(propyl sulfonic acid) imidazole inner salt, 2-methacryloyloxyethyl phosphocholine and 1-(2-methyl) acryloyl-3-(propyl sulfonic acid) imidazole inner salt; and the mercaptan glycol monomer is one or more of 3-mercapto-1,2-propanediol and dithioerythritol. The preparation steps of the sulfonated lignin waterborne polyurethane are as follows: The diisocyanate, polyglycol and catalyst are uniformly mixed in acetone, then inert gas is introduced, the system is heated, the modified zwitterionic monomer and 2-hydroxyethyl disulfide are added to the system for further heating reaction, the sulfonated lignin is added to the system for heating reaction, the temperature of the system is then reduced, and deionized water is added to the system to obtain the sulfonated modified biomass-based waterborne polyurethane.

2. The comb-like sulfonated lignin aqueous polyurethane according to claim 1, characterized in that, The diisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate and diphenyl methane diisocyanate.

3. The comb-like sulfonated lignin aqueous polyurethane according to claim 1, characterized in that, The polyglycol is one or more of polyethylene glycol, polypropylene glycol, polycaprolactone diol and polytetrahydrofuran diol.

4. The comb-like sulfonated lignin aqueous polyurethane according to claim 1, characterized in that, The catalyst is one or more of N,N-dimethylcyclohexylamine, N,N-dimethylpyridine, stannous octoate and dibutyltin dilaurate.

5. The comb-like sulfonated lignin aqueous polyurethane according to claim 1, characterized in that, The preparation steps of the sulfonated lignin are as follows: The sulfonated modified lignin is obtained by uniformly mixing 2-20 parts of lignin monomer, 5-30 parts of sulfonic acid lactone, 1-5 parts of sodium hydroxide and 20-50 parts of acetone, and then reacting at 60-90℃ for 1-3 hours; the lignin monomer is one or more of alkali lignin and dealkalized lignin; and the sulfonic acid lactone is one or more of 1,4-butyric sulfonic acid lactone and 1,3-propanesulfonic acid lactone.

6. A process for the preparation of the aqueous polyurethane of the comb-like sulfonated lignin according to claim 1, characterized by, The steps include: The diisocyanate, polyglycol and catalyst are uniformly mixed in acetone, then inert gas is introduced, the system is heated, the modified zwitterionic monomer and 2-hydroxyethyl disulfide are added to the system for further heating reaction, the sulfonated lignin is added to the system for heating reaction, the temperature of the system is then reduced to below 40℃, and deionized water is added to the system to obtain the sulfonated modified biomass-based waterborne polyurethane.

7. The preparation method according to claim 6, characterized in that The system is heated to 40-80℃ for 1-3 hours, then the modified zwitterionic monomer and 2-hydroxyethyl disulfide are added to the system for further reaction for 1-3 hours, further sulfonated lignin is added to the system for reaction for 2-5 hours, finally the temperature of the system is reduced to below 40℃, then deionized water is added to the system and mixed to obtain a sulfonated modified biomass-based waterborne polyurethane.

8. The comb-shaped sulfonated lignin waterborne polyurethane of claim 1 is preferably applied in the fields of fabrics, leathers, automotive interiors, wood.

9. Use according to claim 8, characterized in that, The comb-shaped sulfonated lignin waterborne polyurethane can be coated onto the surface of a substrate by dipping, rolling, spraying and printing, and dried at 40-80℃ to form a film.

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