Waterborne polyurethane for labor protection gloves and preparation method of waterborne polyurethane

Abstract

The invention relates to the technical field of manufacturing of gum dipping labor protection appliances, in particular to waterborne polyurethane for labor protection gloves and a preparation method of the waterborne polyurethane. According to the waterborne polyurethane for the labor protection gloves, the solid content ranges from 45% to 50%, the viscosity is basically maintained between 56 mPa.s and 58 mPa.s, the average particle size of polyurethane in emulsion ranges from 300 nm to 500 nm, the potential of the emulsion ranges from-35 mV to-50 mV, the waterborne polyurethane has good dispersion stability and high solid content, and after being cured into an adhesive film, the waterborne polyurethane has high strength and good flexibility at the same time; the waterborne polyurethane working gloves obtained by dipping the waterborne polyurethane have excellent friction resistance, tear resistance and penetration resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing impregnated labor protection products, and specifically relates to an aqueous polyurethane for labor protection gloves and a preparation method thereof. Background Art

[0002] Gloves are important protective tools that are essential for protecting the hand skin from damage in our daily life or during labor in special environments. According to their usage functions, gloves can be classified into: flame-retardant gloves, oil-resistant gloves, acid and alkali-resistant gloves, medical gloves, high-temperature-resistant gloves, thermal gloves, labor protection gloves, etc. Among them, labor protection gloves are one of the most commonly used gloves for daily labor protection.

[0003] Most labor protection gloves are made of rubber and plastic. However, untreated rubber and plastic gloves have disadvantages such as difficult demolding and inflexible wearing. Traditional treatment methods often choose to coat some lubricating materials on their surfaces to increase the demolding property and wearing property of the gloves. However, powder lubricants often cause serious environmental pollution during use and production, and can also cause allergic reactions in some people. Therefore, the use of powdered gloves has greatly decreased. In recent years, labor protection latex-impregnated gloves with excellent abrasion resistance and puncture resistance have been favored by people.

[0004] Polyurethane labor protection gloves are favored by people due to their good abrasion resistance and flexible wearing property. With the continuous enhancement of environmental awareness, aqueous polyurethane labor protection gloves have gradually come into people's view.

[0005] Patent technical literature CN113736061A discloses an aqueous polyurethane emulsion without a coagulant for impregnated labor protection products and a preparation method thereof. The aqueous polyurethane emulsion of this invention can not only meet the requirements of stable homogeneous storage, transportation, impregnation production and other process steps of the emulsion within a certain time, but also enable the emulsion to quickly solidify into a film when infiltrating the glove embryo without continuing to penetrate into the inner layer of the glove embryo, preventing glue penetration.

[0006] With the continuous expansion of the application scope of labor protection gloves, traditional labor protection gloves are gradually difficult to meet people's needs. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide an aqueous polyurethane for labor protection gloves and a preparation method thereof, so as to provide an aqueous polyurethane resin for labor protection gloves with good abrasion resistance, making the polyurethane labor protection gloves have excellent demolding property and abrasion resistance.

[0008] Based on the above purpose, the present invention provides a preparation method of an aqueous polyurethane for labor protection gloves, including the following steps: S1: Add chitin and NaBH4 into a sodium hydroxide solution, stir at 90 - 100 °C for 4 - 6 h, perform suction filtration, wash until the pH is 7, and dry to obtain deacetylated chitin; S2: Add deacetylated chitin, 2,2,6,6 - tetramethylpiperidine - N - oxide, and sodium chlorite into a sodium phosphate solution, then add sodium hypochlorite, react at 60 - 70 °C for 2 - 4 h. After the reaction is completed, centrifuge and wash until the pH value equals 7, and finally adjust the pH to 11, perform ultrasonic bath for 2 h, centrifuge, and dry to obtain modified chitin; S3: Add polytetrahydrofuran ether diol into a three - necked flask, evacuate at 80 °C, and pass nitrogen once every 15 min for 90 min. After the evacuation and nitrogen - passing are completed, cool down to 75 °C, add isophorone diisocyanate, and dropwise add stannous octoate. After reacting for 60 min, cool down to 60 °C, add a chain extender and deacetylated chitin, react for 60 min, then cool down to 55 °C, and dropwise add triethylamine into the flask and react for 15 min to obtain a polyurethane prepolymer; S4: Mix the polyurethane prepolymer obtained in S3 with 100 mL of the modified chitin solution, stir at high speed for 90 min to obtain a composite emulsion, then rotary evaporate the composite emulsion at 45 °C for 30 min, and add deionized water to obtain the water - borne polyurethane for labor protection gloves; In step S1, the dosage ratio of the chitin, NaBH4, and sodium hydroxide solution is 3 - 5 g: 0.3 - 0.4 g: 80 - 100 mL; In step S2, the dosage ratio of the deacetylated chitin, 2,2,6,6 - tetramethylpiperidine - N - oxide, sodium chlorite, sodium phosphate solution, and sodium hypochlorite is 1 - 2 g: 0.16 - 0.32 g: 11.3 - 22.6 g: 100 - 120 mL: 5.3 - 10.6 g; In step S3, the dosage ratio of the polytetrahydrofuran ether diol, isophorone diisocyanate, stannous octoate, 2,2 - bis(hydroxymethyl)butyric acid, deacetylated chitin, and triethylamine is 48 - 50 g: 14 - 16 g: 0.15 - 0.2 mL: 3.5 - 4 g: 0.5 - 1 g: 2.4 - 3 g.

[0009] Preferably, the sodium hydroxide solution in step S1 is a 33 w% sodium hydroxide solution.

[0010] Preferably, the sodium phosphate solution in step S1 has a concentration of 0.5 mol / L.

[0011] Preferably, the chain extender in step S3 is 2,2 - bis(hydroxymethyl)butyric acid.

[0012] Preferably, the concentration of the modified chitin solution in step S4 is 1 - 2 w%.

[0013] Preferably, the water - borne polyurethane for labor protection gloves in step S4 is a water - borne polyurethane emulsion with a solid content of 45% - 50%.

[0014] Furthermore, the present invention also provides an aqueous polyurethane for labor protection gloves, which is prepared according to the preparation method of the aqueous polyurethane for labor protection gloves described above.

[0015] Advantages of the present invention: The aqueous polyurethane for labor protection gloves of the present invention has a milky white emulsion appearance, a solid content between 45% and 50%, a viscosity basically maintained between 56 and 58 mPa·s, and an average particle size of the polyurethane in the emulsion between 300 and 500 nm, having good dispersion stability and a high solid content.

[0016] For the aqueous polyurethane for labor protection gloves of the present invention, by first using deacetylated chitin to participate in the polyurethane prepolymerization process and then using modified chitin to participate in the final emulsification process of the prepolymer, the formed rubber film of the aqueous polyurethane for labor protection gloves has excellent mechanical strength and water resistance, and the labor protection gloves impregnated with the aqueous polyurethane emulsion have excellent friction resistance, tear resistance, and penetration resistance. Specific Embodiments

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in detail with reference to specific embodiments.

[0018] Example 1: An aqueous polyurethane for labor protection gloves, and the specific preparation steps are as follows: (1) Add 3 g of chitin and 0.3 g of NaBH4 to 80 mL of 33 w% sodium hydroxide solution, stir at 90 °C for 4 h, then repeatedly filter and wash with deionized water and ethanol until the pH is approximately equal to 7, and place it in a blast drying oven to dry to obtain deacetylated chitin; (2) Add 1 g of deacetylated chitin, 0.16 g of 2,2,6,6-tetramethylpiperidine oxide, and 11.3 g of sodium chlorite to 100 mL of 0.5 mol / L sodium phosphate solution, then add 5.3 g of sodium hypochlorite, react at 60 °C for 2 h. After the reaction, repeatedly wash and centrifuge with deionized water until the pH value is equal to 7, finally adjust the pH to 11, perform ultrasonic bath for 2 h, centrifuge, and dry to obtain modified chitin; (3) Add 48 g of polytetrahydrofuran ether glycol to a three-necked flask, evacuate at 80 °C, and pass nitrogen every 15 min for 90 min. After evacuating and passing nitrogen, cool down to 75 °C, add 14 g of isophorone diisocyanate, and dropwise add 0.15 mL of stannous octoate. After reacting for 60 min, cool down to 60 °C, add 3.5 g of 2,2-dimethylolbutyric acid and 0.5 g of deacetylated chitin. After reacting for 60 min, the temperature is lowered to 55 °C, and 2.4 g of triethylamine is dropwise added to the flask and reacted for 15 min to obtain a polyurethane prepolymer; (4) Mix the polyurethane prepolymer obtained in step (3) with 100 mL of 1 w% modified chitin solution, stir at high speed for 90 min to obtain a composite emulsion, then rotary evaporate the composite emulsion at 45 °C for 30 min, add deionized water to obtain aqueous polyurethane for labor protection gloves with a solid content of 45%.

[0019] Example 2: An aqueous polyurethane for labor protection gloves, the specific preparation steps are as follows: (1) Add 4 g of chitin and 0.35 g of NaBH4 to 90 mL of 33 w% sodium hydroxide solution, stir at 95 °C for 5 h, then repeatedly filter and wash with deionized water and ethanol until the pH is approximately equal to 7, and dry in a blast drying oven to obtain deacetylated chitin; (2) Add 1.5 g of deacetylated chitin, 0.24 g of 2,2,6,6 - tetramethylpiperidine 1 - oxide and 16.9 g of sodium chlorite to 110 mL of 0.5 mol / L sodium phosphate solution, then add 8.0 g of sodium hypochlorite, react at 65 °C for 3 h. After the reaction, repeatedly wash and centrifuge with deionized water until the pH value is equal to 7, finally adjust the pH to 11, perform ultrasonic bath for 2 h, centrifuge, and dry to obtain modified chitin; (3) Add 49 g of polytetrahydrofuran ether glycol to a three - necked flask, evacuate at 80 °C, and pass nitrogen once every 15 min for 90 min. After evacuating and passing nitrogen, cool to 75 °C, add 15 g of isophorone diisocyanate, and dropwise add 0.18 mL of stannous octoate. After reacting for 60 min, cool to 60 °C, add 3.8 g of 2,2 - dimethylolbutanoic acid and 0.8 g of deacetylated chitin. After reacting for 60 min, cool the temperature to 55 °C, and dropwise add 2.7 g of triethylamine into the flask, react for 15 min to obtain a polyurethane prepolymer; (4) Mix the polyurethane prepolymer obtained in step (3) with 100 mL of 1.5 w% modified chitin solution, stir at high speed for 90 min to obtain a composite emulsion, then rotary evaporate the composite emulsion at 45 °C for 30 min, add deionized water to obtain aqueous polyurethane for labor protection gloves with a solid content of 50%.

[0020] Example 3: An aqueous polyurethane for labor protection gloves, the specific preparation steps are as follows: (1) Add 5 g of chitin and 0.4 g of NaBH4 to 100 mL of 33 w% sodium hydroxide solution, stir at 100 °C for 6 h, then repeatedly filter and wash with deionized water and ethanol until the pH is approximately equal to 7, and dry in a blast drying oven to obtain deacetylated chitin; (2) 2 g of deacetylated chitin, 0.32 g of 2,2,6,6-tetramethylpiperidine N-oxide, and 22.6 g of sodium chlorite were added to 120 mL of 0.5 mol / L sodium phosphate solution. Subsequently, 10.6 g of sodium hypochlorite was added, and the reaction was carried out at 70 °C for 4 h. After the reaction, it was washed and centrifuged repeatedly with deionized water until the pH value was equal to 7. Finally, the pH was adjusted to 11, and it was sonicated in a water bath for 2 h, centrifuged, and dried to obtain modified chitin; (3) 50 g of polytetrahydrofuran ether glycol was added to a three-necked flask, evacuated at 80 °C, and nitrogen was passed through every 15 min for 90 min. After evacuation and nitrogen passing were completed, the temperature was lowered to 75 °C, 16 g of isophorone diisocyanate was added, and 0.2 mL of stannous octoate was added dropwise. After reacting for 60 min, the temperature was lowered to 60 °C, 4 g of 2,2-dimethylolbutanoic acid and 1 g of deacetylated chitin were added. After reacting for 60 min, the temperature was lowered to 55 °C, and 3 g of triethylamine was added dropwise into the flask, and the reaction was carried out for 15 min to obtain a polyurethane prepolymer; (4) The polyurethane prepolymer obtained in step (3) was mixed with 100 mL of 2 w% modified chitin solution and stirred at high speed for 90 min to obtain a composite emulsion. Then the composite emulsion was rotary evaporated at 45 °C for 30 min, and deionized water was added to obtain an aqueous polyurethane for labor protection gloves with a solid content of 458%.

[0021] Comparative Example 1: An aqueous polyurethane for labor protection gloves, which is different from Example 2 in that modified chitin is added first and then deacetylated chitin. The specific preparation steps are as follows: (1) 4 g of chitin and 0.35 g of NaBH4 were added to 90 mL of 33 w% sodium hydroxide solution, stirred at 95 °C for 5 h, and then repeatedly filtered and washed with deionized water and ethanol until the pH was approximately equal to 7, and then dried in a blast drying oven to obtain deacetylated chitin; (2) 1.5 g of deacetylated chitin, 0.24 g of 2,2,6,6-tetramethylpiperidine N-oxide, and 16.9 g of sodium chlorite were added to 110 mL of 0.5 mol / L sodium phosphate solution. Subsequently, 8.0 g of sodium hypochlorite was added, and the reaction was carried out at 65 °C for 3 h. After the reaction, it was washed and centrifuged repeatedly with deionized water until the pH value was equal to 7. Finally, the pH was adjusted to 11, and it was sonicated in a water bath for 2 h, centrifuged, and dried to obtain modified chitin; (3) Add 49 g of polytetrahydrofuran ether diol into a three-necked flask, evacuate the air at 80 °C, and pass nitrogen once every 15 min for 90 min. After the evacuation and nitrogen passing are completed, cool down to 75 °C, add 15 g of isophorone diisocyanate, and dropwise add 0.18 mL of stannous octoate. After reacting for 60 min, cool down to 60 °C, add 3.8 g of 2,2-dimethylolbutanoic acid and 0.8 g of modified chitin, react for 60 min, then cool the temperature to 55 °C, and dropwise add 2.7 g of triethylamine into the flask and react for 15 min to obtain a polyurethane prepolymer; (4) Mix the polyurethane prepolymer obtained in step (3) with 100 mL of 1.5 w% deacetylated chitin solution, stir at high speed for 90 min to obtain a composite emulsion, then rotary evaporate the composite emulsion at 45 °C for 30 min, and add deionized water to obtain the waterborne polyurethane for labor protection gloves with a solid content of 50%.

[0022] Comparative Example 2: A waterborne polyurethane for labor protection gloves, which is different from Example 2 in that deacetylated chitin and modified chitin are added together during the prepolymerization process. The specific preparation steps are as follows: (1) Add 4 g of chitin and 0.35 g of NaBH4 into 90 mL of 33 w% sodium hydroxide solution, stir at 95 °C for 5 h, then repeatedly filter and wash with deionized water and ethanol until the pH is approximately equal to 7, and place it in a blast drying oven to dry to obtain deacetylated chitin; (2) Add 1.5 g of deacetylated chitin, 0.24 g of 2,2,6,6-tetramethylpiperidine oxide, and 16.9 g of sodium chlorite into 110 mL of 0.5 mol / L sodium phosphate solution, then add 8.0 g of sodium hypochlorite, react at 65 °C for 3 h. After the reaction is completed, repeatedly wash and centrifuge with deionized water until the pH value is equal to 7, finally adjust the pH to 11, perform water bath ultrasonic treatment for 2 h, centrifuge, and dry to obtain modified chitin; (3) Add 49 g of polytetrahydrofuran ether diol into a three-necked flask, evacuate the air at 80 °C, and pass nitrogen once every 15 min for 90 min. After the evacuation and nitrogen passing are completed, cool down to 75 °C, add 15 g of isophorone diisocyanate, and dropwise add 0.18 mL of stannous octoate. After reacting for 60 min, cool down to 60 °C, add 3.8 g of 2,2-dimethylolbutanoic acid, 0.8 g of deacetylated chitin, and 1.5 g of modified chitin, react for 60 min, then cool the temperature to 55 °C, and dropwise add 2.7 g of triethylamine into the flask and react for 15 min to obtain a polyurethane prepolymer; (4) Mix the polyurethane prepolymer obtained in step (3) with 100 mL of deionized water and stir at high speed for 90 min to obtain a composite emulsion. Then, the composite emulsion is rotary evaporated at 45 °C for 30 min, and deionized water is added to obtain an aqueous polyurethane for labor protection gloves with a solid content of 50%.

[0023] Comparative Example 3: An aqueous polyurethane for labor protection gloves, which is different from Example 2 in that deacetylated chitin and modified chitin are added together during the prepolymer emulsification process. The specific preparation steps are as follows: (1) Add 4 g of chitin and 0.35 g of NaBH4 to 90 mL of 33 w% sodium hydroxide solution, stir at 95 °C for 5 h, then repeatedly filter and wash with deionized water and ethanol until the pH is approximately equal to 7, and place it in a blast drying oven to obtain deacetylated chitin. (2) Add 1.5 g of deacetylated chitin, 0.24 g of 2,2,6,6-tetramethylpiperidine oxide, and 16.9 g of sodium chlorite to 110 mL of 0.5 mol / L sodium phosphate solution, then add 8.0 g of sodium hypochlorite, and react at 65 °C for 3 h. After the reaction, repeatedly wash and centrifuge with deionized water until the pH value is equal to 7, and finally adjust the pH to 11, sonicate in a water bath for 2 h, centrifuge, and dry to obtain modified chitin. (3) Add 49 g of polytetrahydrofuran ether diol to a three-necked flask, evacuate at 80 °C, and pass nitrogen once every 15 min for 90 min. After the evacuation and nitrogen passing are completed, cool to 75 °C, add 15 g of isophorone diisocyanate, and gradually add 0.18 mL of stannous octoate dropwise. After reacting for 60 min, cool to 60 °C, add 3.8 g of 2,2-dimethylolbutyric acid, react for 60 min, then cool the temperature to 55 °C, and gradually add 2.7 g of triethylamine dropwise to the flask and react for 15 min to obtain a polyurethane prepolymer. (4) Mix the polyurethane prepolymer obtained in step (3) with 100 mL of 1.5 w% modified chitin solution and 0.8 g of deacetylated chitin, stir at high speed for 90 min to obtain a composite emulsion. Then, the composite emulsion is rotary evaporated at 45 °C for 30 min, and deionized water is added to obtain an aqueous polyurethane for labor protection gloves with a solid content of 50%.

[0024] Comparative Example 4: An aqueous polyurethane for labor protection gloves, which is different from Example 2 in that only modified chitosan is added. The specific preparation steps are as follows: (1) Add 4 g of chitin and 0.35 g of NaBH4 to 90 mL of 33 w% sodium hydroxide solution, stir at 95 °C for 5 h, then repeatedly filter and wash with deionized water and ethanol until the pH is approximately equal to 7, and place it in a blast drying oven to obtain deacetylated chitin. (2) Add 1.5 g of deacetylated chitin, 0.24 g of 2,2,6,6-tetramethylpiperidine-N-oxide, and 16.9 g of sodium chlorite to 110 mL of 0.5 mol / L sodium phosphate solution. Subsequently, add 8.0 g of sodium hypochlorite and react at 65 °C for 3 h. After the reaction, wash and centrifuge repeatedly with deionized water until the pH value equals 7. Finally, adjust the pH to 11, perform ultrasonic bath for 2 h, centrifuge, and dry to obtain modified chitin; (3) Add 49 g of polytetrahydrofuran ether glycol to a three-necked flask, evacuate the air at 80 °C, and introduce nitrogen every 15 min for 90 min. After the evacuation and nitrogen introduction are completed, cool the temperature to 75 °C, add 15 g of isophorone diisocyanate, and dropwise add 0.18 mL of stannous octoate. After reacting for 60 min, cool the temperature to 60 °C, add 3.8 g of 2,2-dimethylolbutanoic acid, react for 60 min, then cool the temperature to 55 °C, and dropwise add 2.7 g of triethylamine to the flask and react for 15 min to obtain a polyurethane prepolymer; (4) Mix the polyurethane prepolymer obtained in step (3) with 100 mL of 1.5 w% modified chitin solution and stir at high speed for 90 min to obtain a composite emulsion. Then, rotary evaporate the composite emulsion at 45 °C for 30 min, add deionized water to obtain an aqueous polyurethane for labor protection gloves with a solid content of 50%.

[0025] Performance Test Observe the appearance of the aqueous polyurethane emulsions obtained in Examples 1-3, and measure their particle size, viscosity, and potential. The test results are shown in Table 1; Pour the emulsions obtained in the examples and comparative examples onto a polytetrafluoroethylene plate to form a film. After standing at room temperature for 48 h, place it in a vacuum oven at 60 °C for 36 h to obtain a film sample. Use the ASTM standard procedure to stretch at a rate of 50 mm / min and conduct tensile performance tests. The test results are shown in Table 2; While stirring, add 5 g of anti-sticking agent and 5 g of titanium dioxide to the aqueous polyurethanes obtained in the examples and comparative examples, stir evenly, add dyes, and add thickeners to adjust the viscosity to 1800-2500 mPa·s to complete the glue preparation.

[0026] Put the glove embryo into an oven and bake it to 50 °C. Subsequently, first immerse it in a coagulant, take it out and air-dry for 30 s, then immerse it in the prepared aqueous polyurethane slurry, and finally immerse it in the coagulant again. Take it out and air-dry for 90 min, then dry and demold to obtain labor protection gloves with an aqueous polyurethane coating, and conduct tests according to GB24541-2009 "Technical Requirements for Labor Protection Gloves Standards". The test results are shown in Table 2.

[0027]

[0028]

[0029] Data analysis: As can be seen from Examples 1-3 in Tables 1 and 2, the waterborne polyurethane for labor protection gloves of the present invention has a milky white emulsion appearance, the viscosity is basically maintained between 56-58 mPa·s, the average particle size of the polyurethane in the emulsion is between 300-500 nm, the emulsion potential is between -35 mV and -50 mV, having good dispersion stability and a high solid content, and at the same time having excellent mechanical strength and water resistance. While ensuring high strength of the waterborne polyurethane, the flexibility of the rubber film is improved, providing an excellent raw material guarantee for the preparation of waterborne polyurethane-impregnated labor protection gloves.

[0030] As can be seen from Example 2 and Comparative Examples 1 and 4 in Table 2, the present invention first uses deacetylated chitin to participate in the polyurethane prepolymerization process, and then uses modified chitin to participate in the final emulsification process of the prepolymer, so that the rubber film formed by the waterborne polyurethane for labor protection gloves has excellent mechanical strength and water resistance. The gloves impregnated with this waterborne polyurethane emulsion have excellent friction resistance, tear resistance, and puncture resistance. This is mainly because the surface of deacetylated chitin is rich in amino groups. When added at the initial stage of the pre-emulsion synthesis, the hydroxyl and amino groups on its surface react with the isocyanate groups in the prepolymer to form covalent bonds. This reaction forms a stable cross-linked network in the early stage, providing a rigid framework for subsequent enhancement. The carboxyl groups on the surface of modified chitin can combine with the unreacted isocyanate groups, further increasing its cross-linking density. At the same time, the carboxyl groups can form a multi-level enhancement structure through hydrogen bonding, ionic bonding, and physical embedding with polar groups, forming a more complete and tight cross-linked network, greatly improving the mechanical strength and water resistance of the rubber film. Most importantly, the deacetylated chitin inside the cross-linked network can further improve the interfacial compatibility between the modified chitin and the matrix, further enhancing the mechanical strength and water resistance of the rubber film and the wear and puncture resistance of the gloves; when deacetylated chitin and modified chitin are added together as in Example 2 and Comparative Examples 2 and 3, it may be due to the low reaction activity of the carboxyl group with the isocyanate, resulting in low cross-linking efficiency, weakening the network stability, and the interaction between the amino group and the carboxyl group, resulting in a reduction in effective reaction sites and inability to fully combine with the polymer main chain; in addition, when the two are added together, it may cause defects due to agglomeration, thereby destroying the uniformity of the PU matrix, thus reducing the mechanical properties and water resistance.

[0031] Those of ordinary skill in the art should understand that: The discussion of any above embodiment is only exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A preparation method of waterborne polyurethane for labor protection gloves, characterized in that, It includes the following steps: S1: Add chitin and NaBH4 into sodium hydroxide solution, stir at 90 - 100 °C for 4 - 6 h, carry out suction filtration, wash until the pH is 7, and dry to obtain deacetylated chitin; S2: Add deacetylated chitin, 2,2,6,6 - tetramethylpiperidine - N - oxide and sodium chlorite into sodium phosphate solution, then add sodium hypochlorite, react at 60 - 70 °C for 2 - 4 h. After the reaction ends, centrifuge and wash until the pH value equals 7. Finally, adjust the pH to 11, carry out water - bath ultrasonic treatment for 2 h, centrifuge and dry to obtain modified chitin; S3: Add polytetrahydrofuran ether glycol into a three - necked flask, evacuate at 80 °C, and introduce nitrogen once every 15 min for 90 min. After the evacuation and nitrogen introduction end, cool down to 75 °C, add isophorone diisocyanate, and dropwise add stannous octoate. After reacting for 60 min, cool down to 60 °C, add a chain extender and deacetylated chitin. After reacting for 60 min, the temperature drops to 55 °C, and dropwise add triethylamine into the flask and react for 15 min to obtain a polyurethane prepolymer; S4: Mix the polyurethane prepolymer obtained in S3 with 100 mL of modified chitin solution, stir at high speed for 90 min to obtain a composite emulsion. Then rotary evaporate the composite emulsion at 45 °C for 30 min, and add deionized water to obtain water - borne polyurethane for labor protection gloves; In step S1, the dosage ratio of chitin, NaBH4, and sodium hydroxide solution is 3 - 5 g: 0.3 - 0.4 g: 80 - 100 mL; In step S2, the dosage ratio of deacetylated chitin, 2,2,6,6 - tetramethylpiperidine - N - oxide, sodium chlorite, sodium phosphate solution, and sodium hypochlorite is 1 - 2 g: 0.16 - 0.32 g: 11.3 - 22.6 g: 100 - 120 mL: 5.3 - 10.6 g; In step S3, the dosage ratio of polytetrahydrofuran ether glycol, isophorone diisocyanate, stannous octoate, 2,2 - bis(hydroxymethyl)butyric acid, deacetylated chitin, and triethylamine is 48 - 50 g: 14 - 16 g: 0.15 - 0.2 mL: 3.5 - 4 g: 0.5 - 1 g: 2.4 - 3 g.

2. The preparation method of the waterborne polyurethane for labor protection gloves according to claim 1, characterized in that, The concentration of the sodium hydroxide solution described in step S1 is 33 w% sodium hydroxide solution.

3. The preparation method of the waterborne polyurethane for labor protection gloves according to claim 1, characterized in that, The concentration of the sodium phosphate solution described in step S1 is 0.5 mol / L.

4. The preparation method of the waterborne polyurethane for labor protection gloves according to claim 1, characterized in that, The chain extender in step S3 is 2,2 - bis(hydroxymethyl)butyric acid.

5. The preparation method of the waterborne polyurethane for labor protection gloves according to claim 1, characterized in that, The concentration of the modified chitin solution described in step S4 is 1 - 2 w%.

6. The preparation method of the waterborne polyurethane for labor protection gloves according to claim 1, characterized in that, The water - borne polyurethane for labor protection gloves described in step S4 is a water - borne polyurethane emulsion with a solid content of 45% - 50%.

7. An aqueous polyurethane for labor protection gloves, characterized in that, It is prepared according to the preparation method of the water - borne polyurethane for labor protection gloves described in any one of claims 1 - 6.

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