Modified negative oxygen ion leather finishing agent and preparation method thereof

Abstract

The invention relates to the technical field of leather auxiliaries, and discloses a modified negative oxygen ion leather finishing agent and a preparation method thereof.The modified negative oxygen ion leather finishing agent is obtained by adding negative oxygen ion nanometer liquid, modified polyurethane, epoxy chitosan, polyethylene glycol and water into a stirrer and stirring. In the stirring process, a terminal hydroxyl group in the modified polyurethane and an epoxy group in the epoxy group chitosan are subjected to a ring-opening reaction and are cross-linked with each other, and a stable molecular contact network is formed and is better adsorbed on the surface of leather, so that the leather finishing agent is better adsorbed on the surface of the leather. The sulfur element and the phosphorus element in the modified polyurethane have better flame-retardant effects, and form a flame-retardant system together with a chitosan molecular structure in the epoxy chitosan. Chitosan and quaternary ammonium salt in the epoxy chitosan have a relatively good antibacterial effect.

Description

Technical Field

[0001] The invention relates to the technical field of leather auxiliaries, in particular to a modified negative oxygen ion leather finishing agent and a preparation method thereof. Background Art

[0002] Negative oxygen ion leather has antibacterial, sterilizing and deodorizing functions, which makes it better in keeping clean and hygienic. However, during long-term use, negative oxygen ion powder is easy to fall off from the leather, thereby affecting the quality of the leather. At the same time, in the process of use, when encountering fire, it will be flammable and will also affect its normal use. Therefore, how to avoid these phenomena is the key to solving the problem. For example, patent CN104356342B discloses a silicone-modified water-based polyurethane leather finishing agent and a preparation method. The water-based polyurethane emulsion synthesized by the invention has significant improvements in water resistance, cold resistance, solvent resistance, surface characteristics, etc., and the process is simple and easy to operate, but its flame retardant and antibacterial effects are poor. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] In view of the deficiencies of the prior art, the present invention provides a modified negative oxygen ion leather finishing agent and a preparation method thereof, which has good flame retardant and antibacterial effects.

[0005] (II) Technical solution

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a modified negative oxygen ion leather finishing agent, comprising the following weight components: 0.4-0.6 weight parts of negative oxygen ion nano liquid, 1-3 weight parts of modified polyurethane, 2-3 weight parts of epoxy chitosan, 1-2 weight parts of polyethylene glycol, and 70-80 weight parts of water.

[0007] Preferably, the preparation method of the modified polyurethane is:

[0008] S1. Disperse microcrystalline cellulose into a reactor filled with distilled water, then add 16-18% sulfuric acid solution to adjust the pH to 2-2.4, stir for 22-25 minutes, then continue to add sodium periodate, and react at 25-35° C. in a dark place for 8-10 hours. After the reaction, add ethylene glycol for washing, filter, wash with deionized water and anhydrous ethanol in turn, and vacuum dry to obtain dialdehyde cellulose;

[0009] S2. Add dialdehyde cellulose and 2-aminoethanethiol to ethanol, raise the temperature to 30-40°C and react for 6-8h, then add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, react at 60-75°C for 2-3h, cool to room temperature after reaction, precipitate, filter and recrystallize the product with ethanol to obtain intermediate 1;

[0010] S3. Add magnolol to N,N-dimethylformamide solvent, stir and disperse, then add intermediate 1 and benzoin dimethyl ether photoinitiator, irradiate with 365nm ultraviolet light for 2-5h at 30-50°C, centrifuge after completion, wash and dry to obtain a cellulose-based chain extender;

[0011] S4. After removing water from the polyether diol, mix it evenly with hexamethylene diisocyanate, introduce nitrogen, then add dibutyltin dilaurate catalyst dropwise, react at 60-80°C for 3-6 hours to carry out prepolymerization, then add cellulose-based chain extender, stir to continue chain extension reaction, react at 40-50°C for 4-6 hours, and after the reaction is completed, cool and discharge to obtain modified polyurethane.

[0012] Preferably, the mass ratio of microcrystalline cellulose, sulfuric acid and sodium periodate in S1 is 1:0.1-0.3:1.1-1.3.

[0013] Preferably, the mass ratio of dialdehyde cellulose, 2-aminoethanethiol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in S2 is 1:2.4-2.9:1.6-1.8.

[0014] Preferably, the mass ratio of magnolol, intermediate 1 and dimethyl benzoate photoinitiator in S3 is 0.9-1.3:1:0.01-0.02.

[0015] Preferably, the mass ratio of the polyether diol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and cellulose-based chain extender in S4 is 1:1.1-1.2:0.02-0.04:0.3-0.5.

[0016] Preferably, the preparation method of the epoxy chitosan is:

[0017] Step 1: add 6-9 parts by weight of chitosan to dimethyl sulfoxide solvent to dissolve, heat in a water bath at 65-90° C., add 5-8 parts by weight of 2,3-epoxypropyltrimethylammonium chloride at constant pressure, react for 6-8 hours, wash with anhydrous ethanol after the reaction, dry, dialyze, and concentrate to obtain quaternized chitosan;

[0018] Step 2: Add 4-8 parts by weight of quaternized chitosan and 6-12 parts by weight of epichlorohydrin into N,N-dimethylformamide solvent, stir evenly, react at 80-110° C. for 10-14 hours, and then perform reduced pressure distillation, filter and dry to obtain epoxy chitosan.

[0019] Preferably, the preparation method of the modified negative oxygen ion leather finishing agent is: adding negative oxygen ion nano liquid, modified polyurethane, epoxy chitosan, polyethylene glycol, and water into a stirrer, stirring for 3-6 minutes, and evaporating and concentrating to a solid content of 6% to obtain the modified negative oxygen ion leather finishing agent.

[0020] (III) Beneficial technical effects

[0021] The invention prepares the modified negative oxygen ion leather finishing agent by adding negative oxygen ion nano liquid, modified polyurethane, epoxy chitosan, polyethylene glycol and water into a stirrer and stirring the mixture.

[0022] During the stirring process, the terminal hydroxyl groups in the modified polyurethane will undergo a ring-opening reaction with the epoxy groups in the epoxy chitosan, resulting in cross-linking between each other to form a stable molecular network, which is better adsorbed on the leather surface, allowing the leather finishing agent to be better adsorbed on the leather surface.

[0023] The sulfur and phosphorus elements in the modified polyurethane have good flame retardant effects and together with the chitosan molecular structure in the epoxy chitosan, they constitute a flame retardant system; and after the dialdehyde cellulose and 2-aminoethanethiol react, the intermediate 1 is obtained, which further increases the degree of substitution of sulfur and phosphorus elements, making it more flame retardant. The chitosan and quaternary ammonium salt in the epoxy chitosan have good antibacterial effects. DETAILED DESCRIPTION

[0024] Negative oxygen ion nano liquid: tourmaline and monazite are ground to 400 mesh to obtain tourmaline powder and monazite powder; the tourmaline powder, monazite powder and infrared tourmaline powder are mixed and stirred at a weighing ratio of 15:50:20, the mixed tourmaline powder, monazite powder and infrared tourmaline powder are added into a 60% NaOH (sodium hydroxide) reactor and stirred at 200 revolutions per minute for 30 minutes, then left to stand for 3 hours, stirred for a second time for 30 minutes, introduced into a wet ball mill for grinding, and ground repeatedly to make the grinding particle size reach 0.5 microns to obtain negative oxygen ion nano liquid.

[0025] Example 1

[0026] (1) Dispersing microcrystalline cellulose into a reactor filled with distilled water, then adding 16% sulfuric acid to adjust the pH of the solution to 2, stirring for 22 minutes, and then continuing to add sodium periodate, wherein the mass ratio of microcrystalline cellulose, sulfuric acid, and sodium periodate is 1:0.1:1.1, and reacting at 25° C. in a dark place for 8 hours. After the reaction, adding ethylene glycol for washing, filtering, washing with deionized water and anhydrous ethanol in turn, and vacuum drying to obtain dialdehyde cellulose;

[0027] (2) adding dialdehyde cellulose and 2-aminoethanethiol to ethanol, heating to 30° C. for reaction for 6 h, and then adding 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, wherein the mass ratio of dialdehyde cellulose, 2-aminoethanethiol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:2.4:1.6, and reacting at 60° C. for 2 h. After the reaction, cooling to room temperature, precipitating a precipitate, filtering the product, and recrystallizing it with ethanol to obtain intermediate 1;

[0028] (3) adding magnolol to N,N-dimethylformamide solvent, stirring and dispersing, and then adding intermediate 1 and benzoin dimethyl ether photoinitiator, wherein the mass ratio of magnolol, intermediate 1, and benzoin dimethyl ether photoinitiator is 0.9:1:0.01, irradiating with 365nm ultraviolet light at 30°C for 2h, centrifuging after the end, washing and drying to obtain a cellulose-based chain extender;

[0029] (4) removing water from the polyether diol and mixing it evenly with hexamethylene diisocyanate, introducing nitrogen, then dropping a dibutyltin dilaurate catalyst, reacting at 60° C. for 3 hours, performing prepolymerization, and then adding a cellulose-based chain extender, wherein the mass ratio of the polyether diol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and cellulose-based chain extender is 1:1.1:0.02:0.3, stirring to continue the chain extension reaction, reacting at 40° C. for 4 hours, and after the reaction is completed, cooling and discharging to obtain a modified polyurethane;

[0030] (5) adding 6 parts by weight of chitosan to dimethyl sulfoxide solvent to dissolve it, heating it in a water bath at 65° C., adding 5 parts by weight of 2,3-epoxypropyltrimethylammonium chloride at constant pressure, reacting it for 6 hours, washing it with anhydrous ethanol after the reaction, drying it, dialyzing it, and concentrating it to obtain quaternized chitosan;

[0031] (6) adding 4 parts by weight of quaternized chitosan and 6 parts by weight of epichlorohydrin to N,N-dimethylformamide solvent, stirring evenly, reacting at 80° C. for 10 h, and then distilling under reduced pressure, filtering and drying to obtain epoxy chitosan;

[0032] (7) 0.4 parts by weight of negative oxygen ion nano-liquid, 1 part by weight of modified polyurethane, 2 parts by weight of epoxy chitosan, 1 part by weight of polyethylene glycol, and 70 parts by weight of water were added into a stirrer and stirred for 3 minutes to obtain a modified negative oxygen ion leather finishing agent.

[0033] Example 2

[0034] (1) Dispersing microcrystalline cellulose into a reactor filled with distilled water, then adding 18% sulfuric acid solution to adjust the pH to 2.4, stirring for 25 minutes, and then continuing to add sodium periodate, wherein the mass ratio of microcrystalline cellulose, sulfuric acid, and sodium periodate is 1:0.3:1.3, and reacting at 35° C. in a dark place for 10 hours. After the reaction, adding ethylene glycol for washing, filtering, washing with deionized water and anhydrous ethanol in turn, and vacuum drying to obtain dialdehyde cellulose;

[0035] (2) adding dialdehyde cellulose and 2-aminoethanethiol to ethanol, heating to 40° C. for reaction for 8 h, and then adding 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, wherein the mass ratio of dialdehyde cellulose, 2-aminoethanethiol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:2.9:1.8, and reacting at 75° C. for 3 h. After the reaction, cooling to room temperature, precipitating a precipitate, filtering the product, and recrystallizing it with ethanol to obtain intermediate 1;

[0036] (3) adding magnolol to N,N-dimethylformamide solvent, stirring and dispersing, and then adding intermediate 1 and benzoin dimethyl ether photoinitiator, wherein the mass ratio of magnolol, intermediate 1, and benzoin dimethyl ether photoinitiator is 1.3:1:0.02, irradiating with 365nm ultraviolet light at 50°C for 5h, centrifuging after the end, washing and drying to obtain a cellulose-based chain extender;

[0037] (4) removing water from the polyether diol and mixing it evenly with hexamethylene diisocyanate, introducing nitrogen, then dropping a dibutyltin dilaurate catalyst, reacting at 80° C. for 6 hours, performing prepolymerization, and then adding a cellulose-based chain extender, wherein the mass ratio of the polyether diol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and cellulose-based chain extender is 1:1.2:0.04:0.5, stirring to continue the chain extension reaction, reacting at 50° C. for 6 hours, cooling and discharging after the reaction to obtain a modified polyurethane;

[0038] (5) adding 9 parts by weight of chitosan to dimethyl sulfoxide solvent to dissolve it, heating it in a water bath at 90° C., adding 8 parts by weight of 2,3-epoxypropyltrimethylammonium chloride at constant pressure, reacting it for 8 hours, washing it with anhydrous ethanol after the reaction, drying it, dialyzing it, and concentrating it to obtain quaternized chitosan;

[0039] (6) adding 8 parts by weight of quaternized chitosan and 12 parts by weight of epichlorohydrin to N,N-dimethylformamide solvent, stirring evenly, reacting at 110° C. for 14 h, and then performing reduced pressure distillation after the reaction, filtering and drying to obtain epoxy chitosan;

[0040] (7) 0.6 parts by weight of negative oxygen ion nano-liquid, 3 parts by weight of modified polyurethane, 3 parts by weight of epoxy chitosan, 2 parts by weight of polyethylene glycol, and 80 parts by weight of water were added into a stirrer and stirred for 6 minutes to obtain a modified negative oxygen ion leather finishing agent.

[0041] Example 3

[0042] (1) Dispersing microcrystalline cellulose into a reactor filled with distilled water, then adding 17% sulfuric acid to adjust the pH of the solution to 2.2, stirring for 24 minutes, and then continuing to add sodium periodate, wherein the mass ratio of microcrystalline cellulose, sulfuric acid, and sodium periodate is 1:0.2:1.2, and reacting at 30° C. in a dark place for 9 hours. After the reaction, ethylene glycol is added for washing, and the mixture is filtered, washed with deionized water and anhydrous ethanol in turn, and vacuum dried to obtain dialdehyde cellulose;

[0043] (2) adding dialdehyde cellulose and 2-aminoethanethiol to ethanol, heating to 35° C. for reaction for 7 h, and then adding 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, wherein the mass ratio of dialdehyde cellulose, 2-aminoethanethiol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:2.6:1.7, and reacting at 70° C. for 2 h. After the reaction, cooling to room temperature, precipitating a precipitate, filtering the product, and recrystallizing it with ethanol to obtain intermediate 1;

[0044] (3) adding magnolol to N,N-dimethylformamide solvent, stirring and dispersing, and then adding intermediate 1 and benzoin dimethyl ether photoinitiator, wherein the mass ratio of magnolol, intermediate 1, and benzoin dimethyl ether photoinitiator is 1.2:1:0.015, irradiating with 365nm ultraviolet light at 40°C for 4h, centrifuging after the end, washing and drying to obtain a cellulose-based chain extender;

[0045] (4) removing water from the polyether diol and mixing it evenly with hexamethylene diisocyanate, introducing nitrogen, then dropping a dibutyltin dilaurate catalyst, reacting at 70° C. for 5 hours, performing prepolymerization, and then adding a cellulose-based chain extender, wherein the mass ratio of the polyether diol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and cellulose-based chain extender is 1:1.1:0.03:0.4, stirring to continue the chain extension reaction, reacting at 45° C. for 5 hours, cooling and discharging after the reaction to obtain a modified polyurethane;

[0046] (5) adding 7 parts by weight of chitosan to dimethyl sulfoxide solvent to dissolve it, heating it in a water bath at 80° C., adding 6 parts by weight of 2,3-epoxypropyltrimethylammonium chloride at constant pressure, reacting it for 7 hours, washing it with anhydrous ethanol after the reaction, drying it, dialyzing it, and concentrating it to obtain quaternized chitosan;

[0047] (6) adding 6 parts by weight of quaternized chitosan and 10 parts by weight of epichlorohydrin to N,N-dimethylformamide solvent, stirring evenly, reacting at 90° C. for 12 h, and then distilling under reduced pressure, filtering and drying to obtain epoxy chitosan;

[0048] (7) 0.5 parts by weight of negative oxygen ion nano-liquid, 2 parts by weight of modified polyurethane, 2 parts by weight of epoxy chitosan, 1.5 parts by weight of polyethylene glycol, and 75 parts by weight of water were added into a stirrer and stirred for 5 minutes to obtain a modified negative oxygen ion leather finishing agent.

[0049] Example 4

[0050] (1) Dispersing microcrystalline cellulose into a reactor filled with distilled water, then adding 16% sulfuric acid to adjust the pH of the solution to 2, stirring for 22 minutes, and then continuing to add sodium periodate, wherein the mass ratio of microcrystalline cellulose, sulfuric acid, and sodium periodate is 1:0.1:1.1, and reacting at 25° C. in a dark place for 8 hours. After the reaction, adding ethylene glycol for washing, filtering, washing with deionized water and anhydrous ethanol in turn, and vacuum drying to obtain dialdehyde cellulose;

[0051] (2) adding dialdehyde cellulose and 2-aminoethanethiol to ethanol, heating to 30° C. for reaction for 6 h, and then adding 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, wherein the mass ratio of dialdehyde cellulose, 2-aminoethanethiol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:2.4:1.6, and reacting at 60° C. for 2 h. After the reaction, cooling to room temperature, precipitating a precipitate, filtering the product, and recrystallizing it with ethanol to obtain intermediate 1;

[0052] (3) adding magnolol to N,N-dimethylformamide solvent, stirring and dispersing, and then adding intermediate 1 and benzoin dimethyl ether photoinitiator, wherein the mass ratio of magnolol, intermediate 1, and benzoin dimethyl ether photoinitiator is 1.3:1:0.02, irradiating with 365nm ultraviolet light at 50°C for 5h, centrifuging after the end, washing and drying to obtain a cellulose-based chain extender;

[0053] (4) removing water from the polyether diol and mixing it evenly with hexamethylene diisocyanate, introducing nitrogen, then dropping a dibutyltin dilaurate catalyst, reacting at 80° C. for 6 hours, performing prepolymerization, and then adding a cellulose-based chain extender, wherein the mass ratio of the polyether diol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and cellulose-based chain extender is 1:1.2:0.04:0.5, stirring to continue the chain extension reaction, reacting at 50° C. for 6 hours, cooling and discharging after the reaction to obtain a modified polyurethane;

[0054] (5) adding 7 parts by weight of chitosan to dimethyl sulfoxide solvent to dissolve it, heating it in a water bath at 80° C., adding 6 parts by weight of 2,3-epoxypropyltrimethylammonium chloride at constant pressure, reacting it for 7 hours, washing it with anhydrous ethanol after the reaction, drying it, dialyzing it, and concentrating it to obtain quaternized chitosan;

[0055] (6) adding 6 parts by weight of quaternized chitosan and 10 parts by weight of epichlorohydrin to N,N-dimethylformamide solvent, stirring evenly, reacting at 90° C. for 12 h, and then distilling under reduced pressure, filtering and drying to obtain epoxy chitosan;

[0056] (7) 0.5 parts by weight of negative oxygen ion nano-liquid, 2 parts by weight of modified polyurethane, 2 parts by weight of epoxy chitosan, 1.5 parts by weight of polyethylene glycol, and 75 parts by weight of water were added into a stirrer and stirred for 5 minutes to obtain a modified negative oxygen ion leather finishing agent.

[0057] Comparative Example 1

[0058] Compared with Example 4, this comparative example differs in that no modified polyurethane is added.

[0059] Comparative Example 2

[0060] Compared with Example 4, this comparative example is different in that epoxy chitosan is not added.

[0061] The modified negative oxygen ion leather finishing agent was dried, pressed and cut into samples with a diameter of 4 cm and a thickness of 2 mm. Staphylococcus aureus, Escherichia coli or Candida albicans were used as test strains. 0.5 mL of the bacterial suspension of the test strain (concentration of 1×106 CFU / mL) was transferred into a sterile culture dish containing beef extract peptone medium, and then the sample was attached to the surface of the culture medium and cultured in a constant temperature incubator at 37°C for 24 h. After culture, the diameter of the inhibition zone was measured. The test results are shown in Table 1.

[0062] Table 1: Antimicrobial testing.

[0063]

[0064]

[0065] As can be seen from Table 1, Examples 1-4 of the present invention have larger inhibition zone diameters than Comparative Examples 1-2, indicating better antibacterial effects.

[0066] Use an oxygen index meter to test the limiting oxygen index of the coating; use a horizontal and vertical combustion instrument to test the combustion level of the coating.

[0067] Table 2: Flame retardancy test.

[0068] project Limiting oxygen index (%) Combustion level Example 1 31 V-0 Example 2 32 V-0 Example 3 30 V-0 Example 4 31 V-0 Comparative Example 1 20 V-1 Comparative Example 2 21 V-1

[0069] It can be seen from Table 2 that the flame retardant effect of Examples 1-4 is better than that of Comparative Examples 1-2, which indicates that the coating agent prepared by the present invention has a good flame retardant effect.

[0070] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A modified negative oxygen ion leather finishing agent, characterized in that: The invention comprises the following components by weight: 0.4-0.6 parts by weight of negative oxygen ion nano liquid, 1-3 parts by weight of modified polyurethane, 2-3 parts by weight of epoxy chitosan, 1-2 parts by weight of polyethylene glycol and 70-80 parts by weight of water.

2. The modified negative oxygen ion leather finishing agent according to claim 1, characterized in that: The preparation method of the modified polyurethane is: S1. Disperse microcrystalline cellulose into a reactor filled with distilled water, then add 16-18% sulfuric acid solution to adjust the pH to 2-2.4, stir for 22-25 minutes, then continue to add sodium periodate, and react at 25-35° C. in a dark place for 8-10 hours. After the reaction, add ethylene glycol for washing, filter, wash with deionized water and anhydrous ethanol in turn, and vacuum dry to obtain dialdehyde cellulose; S2. Add dialdehyde cellulose and 2-aminoethanethiol to ethanol, raise the temperature to 30-40°C and react for 6-8h, then add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, react at 60-75°C for 2-3h, cool to room temperature after reaction, precipitate, filter and recrystallize the product with ethanol to obtain intermediate 1; S3. Add magnolol to N,N-dimethylformamide solvent, stir and disperse, then add intermediate 1 and benzoin dimethyl ether photoinitiator, irradiate with 365nm ultraviolet light for 2-5h at 30-50°C, centrifuge after completion, wash and dry to obtain a cellulose-based chain extender; S4. After removing water from the polyether diol, mix it evenly with hexamethylene diisocyanate, introduce nitrogen, then add dibutyltin dilaurate catalyst dropwise, react at 60-80°C for 3-6 hours to carry out prepolymerization, then add cellulose-based chain extender, stir to continue chain extension reaction, react at 40-50°C for 4-6 hours, and after the reaction is completed, cool and discharge to obtain modified polyurethane.

3. The modified negative oxygen ion leather finishing agent according to claim 2, characterized in that: The mass ratio of microcrystalline cellulose, sulfuric acid and sodium periodate in S1 is 1:0.1-0.3:1.1-1.

3.

4. The modified negative oxygen ion leather finishing agent according to claim 2, characterized in that: The mass ratio of dialdehyde cellulose, 2-aminoethanethiol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in S2 is 1:2.4-2.9:1.6-1.

8.

5. The modified negative oxygen ion leather finishing agent according to claim 2, characterized in that: The mass ratio of magnolol, intermediate 1 and benzoin dimethyl ether photoinitiator in S3 is 0.9-1.3:1:0.01-0.

02.

6. The modified negative oxygen ion leather finishing agent according to claim 2, characterized in that: The mass ratio of the polyether diol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst and cellulose-based chain extender in S4 is 1:1.1-1.2:0.02-0.04:0.3-0.

5.

7. The modified negative oxygen ion leather finishing agent according to claim 1, characterized in that: The preparation method of the epoxy chitosan is: Step 1: add 6-9 parts by weight of chitosan to dimethyl sulfoxide solvent to dissolve, heat in a water bath at 65-90° C., add 5-8 parts by weight of 2,3-epoxypropyltrimethylammonium chloride at constant pressure, react for 6-8 hours, wash with anhydrous ethanol after the reaction, dry, dialyze, and concentrate to obtain quaternized chitosan; Step 2: Add 4-8 parts by weight of quaternized chitosan and 6-12 parts by weight of epichlorohydrin into N,N-dimethylformamide solvent, stir evenly, react at 80-110° C. for 10-14 hours, and then perform reduced pressure distillation, filter and dry to obtain epoxy chitosan.

8. A method for preparing the modified negative oxygen ion leather finishing agent according to any one of claims 1 to 7, characterized in that: The preparation method of the modified negative oxygen ion leather finishing agent is as follows: adding negative oxygen ion nano liquid, modified polyurethane, epoxy chitosan, polyethylene glycol and water into a stirrer, stirring for 3-6 minutes, and obtaining the modified negative oxygen ion leather finishing agent.

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