Starch-based waterborne polyurethane sand solidification agent and preparation method thereof

Abstract

The invention belongs to the field of polymer sand solidification agents, and particularly relates to a starch-based waterborne polyurethane sand solidification agent and a preparation method thereof. A self-emulsifying method is adopted, the dosage of isocyanate, the time and temperature of starch participating in a polymerization reaction and the adding proportion of starch are accurately regulated and controlled, and starch molecules are effectively grafted to the waterborne polyurethane sand solidification agent in a covalent binding mode, so that waterborne polyurethane and a starch matrix are uniformly fused. The solid content is controlled by adjusting the addition amount of water, so that the sand solidification agent has relatively low viscosity and good construction performance. Finally, the starch-based waterborne polyurethane sand solidification agent which has the ecological environment-friendly characteristic, construction convenience and excellent sand solidification performance is prepared. The sand solidification agent takes water as a solvent, is safe and harmless in the use process, is friendly to human beings and environment, and meets the green and environment-friendly standard; and after the moisture is volatilized, the cementing effect of polyurethane and the gelatinization effect of starch cooperate to stabilize sand, so that the long-term stability of the sandy soil body is ensured.

Description

Technical Field

[0001] The present invention belongs to the field of polymer sand stabilizers, and particularly relates to a starch-based aqueous polyurethane sand stabilizer and a preparation method thereof. Background Art

[0002] Due to the light mass of sand grains and the weak binding force between sand grains, under the action of natural factors such as strong winds and rainfall, sand grains are extremely prone to movement, deserts migrate, resulting in a reduction in the available land area and an exacerbation of desertification. In order to effectively contain the spread of desertification, sand fixation technology has become the main means of preventing desertification. Currently, common sand fixation methods include mechanical sand fixation, plant sand fixation, and chemical sand fixation. As a main method of chemical sand fixation, polymer sand stabilizers can form a continuous sheet consolidation layer between sand grains due to their high molecular weight, excellent mechanical properties, and film-forming characteristics, improve the weak binding state between sand grains, significantly enhance the binding force between sand grains, and effectively prevent the movement of sand grains. Therefore, they have been widely used in the field of sand fixation. Currently, typical polymer sand stabilizers include polyvinyl acetate, polyacrylate, polyacrylamide, and polyurethane. These sand stabilizers usually exist in the form of polymer solutions. When organic solvents are used as solvents, they are highly toxic, have high viscosity, and poor permeability; when water is used as a solvent, they are environmentally friendly, have low viscosity, and good permeability. The aqueous system often has the problem of reduced sand fixation effect. By introducing starch into the aqueous polyurethane sand stabilizer in a covalent bonding manner, and combining the cementing effect of polyurethane and the gelatinization effect of starch to synergistically fix sand, a more excellent sand fixation effect is achieved, providing an efficient and environmentally friendly solution for desertification control. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide, in view of the deficiencies of the prior art, a self-emulsification method, by precisely controlling the dosage of isocyanate, the time and temperature of starch participating in the polymerization reaction, and the addition ratio of starch, effectively grafting starch molecules onto the aqueous polyurethane sand stabilizer in a covalent bonding manner, so as to achieve uniform fusion of the aqueous polyurethane and the starch matrix. By adjusting the addition amount of water to control the solid content, the sand stabilizer has a low viscosity and good construction performance. Finally, a starch-based aqueous polyurethane sand stabilizer with ecological and environmental protection characteristics, construction convenience, and excellent sand fixation performance is prepared.

[0004] To solve the above technical problems, the present invention discloses a preparation method of a starch-based aqueous polyurethane sand stabilizer, which includes the following steps:

[0005] S1. Mix isophorone diisocyanate and polytetrahydrofuran diol-1000 evenly, add a catalyst, and carry out a prepolymerization reaction to obtain a prepolymer;

[0006] S2. Add 2,2-dimethylolpropionic acid to the prepolymer, and carry out a chain extension reaction after adding a catalyst to obtain a chain-extended material;

[0007] S3. Add a solvent to the chain-extended material to reduce its viscosity, then add starch and a catalyst, and react to obtain starch-grafted polyurethane;

[0008] S4. Add a solvent to the starch-grafted polyurethane to reduce its viscosity, neutralize it with triethylamine to form a salt, add deionized water for emulsification, and remove the solvent to obtain the starch-based waterborne polyurethane sand consolidant.

[0009] Among them, the molar ratio of isophorone diisocyanate, polytetrahydrofuran diol-1000 and 2,2-dimethylolpropionic acid is 3.2:1:2.

[0010] Among them, the catalyst is dibutyltin dilaurate; the dosage of dibutyltin dilaurate is 0.01-0.1% of the system mass;

[0011] Preferably, the dosage of dibutyltin dilaurate is 0.1% of the system mass.

[0012] Among them, the solvent includes any one of acetone, methyl ethyl ketone and ethyl acetate; the dosage of the solvent is 15-30% of the system mass;

[0013] Preferably, the dosage of the solvent is 20% of the system mass.

[0014] Among them, in S1, for the prepolymerization reaction, the reaction temperature is 80-90 °C and the reaction time is 1 hour;

[0015] Preferably, for the prepolymerization reaction, the reaction temperature is 80 °C.

[0016] Among them, in S2, for the chain extension reaction, the reaction temperature is 80-90 °C and the reaction time is 2 hours;

[0017] Preferably, for the chain extension reaction, the reaction temperature is 80 °C.

[0018] Among them, in S3, the dosage of the starch is 1-5% of the system mass; for the reaction, the reaction temperature is 90-100 °C and the reaction time is 20-40 minutes;

[0019] Preferably, the dosage of the starch is 3% of the system mass; for the reaction, the reaction temperature is 95 °C and the reaction time is 30 minutes.

[0020] Specifically, the starch includes any one of soluble mung bean starch, cassava starch, sweet potato starch, potato starch and corn starch.

[0021] Among them, in S4, for the triethylamine, its neutralization degree is 80-100% during the neutralization and salification process; the dosage of deionized water is 65-75% of the system mass;

[0022] Preferably, for the triethylamine, its neutralization degree is 100% during the neutralization and salification process; the dosage of deionized water is 70% of the system mass.

[0023] Among them, in S4, the emulsification is shear emulsification, with a rotation speed of 2000 r / min, a temperature of room temperature, and a time of 15 minutes.

[0024] Furthermore, the starch-based waterborne polyurethane sand-fixing agent prepared by the above preparation method is also within the protection scope of the present invention;

[0025] Specifically, the starch-based waterborne polyurethane sand-fixing agent prepared by the above preparation method has a milky white semi-transparent appearance, a viscosity of 20-65 mPa·s at 25 °C, a solid content of 25-35 wt%, a pH value of 6-8, an average particle size of the emulsion of 30-80 nm, and a storage stability of more than 6 months.

[0026] Furthermore, the application of the starch-based waterborne polyurethane sand-fixing agent prepared by the above preparation method in the field of land desertification control is also within the protection scope of the present invention;

[0027] Specifically, in some embodiments of the present invention, a starch-based waterborne polyurethane sand-fixing agent is prepared by the above preparation method. By characterizing the compressive performance, permeability performance, and wind erosion resistance of the starch-based waterborne polyurethane sand-fixing agent for solidifying sand, it is shown that the starch-based waterborne polyurethane sand-fixing agent provided by the present invention can effectively consolidate sand, has excellent permeability performance, and the sand solidified by it has excellent wind erosion resistance, demonstrating its application prospect in the field of land desertification control.

[0028] Beneficial effects:

[0029] 1. Environmental protection: The sand-fixing agent uses water as a solvent, is safe and harmless during use, is friendly to humans and the environment, and meets the green environmental protection standards.

[0030] 2. Good construction performance: By controlling the solid content and reducing the viscosity of the sand-fixing agent, it is easier to spray and construct outdoors.

[0031] 3. Excellent sand-fixing effect: After the water evaporates, the cementing effect of polyurethane and the gelatinization effect of starch cooperate to fix sand, ensuring the long-term stability of the sand body. Description of the drawings

[0032] The following further specifically describes the present invention in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0033] Figure 1 This is the compressive strength curve graph of the starch-based waterborne polyurethane sand stabilizers A - F curing sand in the embodiments of the present invention.

[0034] Figure 2 This is the schematic diagram of the wind erosion simulation experimental device in the embodiments of the present invention. Specific Embodiments

[0035] In the following embodiments, the experimental methods are all conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0036] Example 1: Preparation of Starch-based Waterborne Polyurethane Sand Stabilizer A

[0037] In this example, the molar ratio of the raw materials isophorone diisocyanate (IPDI), polytetrahydrofuran diol - 1000 (PTMG - 1000), and 2,2 - dimethylolpropionic acid (DMPA) is 3.2:1:2.

[0038] Add 40.41 g of dehydrated polytetrahydrofuran diol - 1000 (PTMG - 1000) and 28.75 g of isophorone diisocyanate (IPDI) into a detachable separable four - necked flask equipped with a stirrer and a condenser tube. Dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). Evacuate and introduce nitrogen gas, and react at 80 °C for 1 hour. Add 10.84 g of dried 2,2 - dimethylolpropionic acid (DMPA), dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL), and react at 80 °C for 2 hours. Add an appropriate amount of solvent to reduce the viscosity. Raise the temperature to 95 °C, add 0.40 g of starch (ST) which is 0.5% (by mass of the system), dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). After reacting for 30 minutes, cool down to 40 °C, add an appropriate amount of solvent to reduce the viscosity, add 8.18 g of triethylamine (TEA) and react for 30 minutes. Add 207.84 g of deionized water which is 70% (by mass of the system), and shear - emulsify at room temperature at 2000 r / min for 15 minutes. Finally, remove the solvent by rotary evaporation to obtain a milky semi - transparent starch - based waterborne polyurethane emulsion, which is the starch - based waterborne polyurethane sand stabilizer A.

[0039] The starch - based waterborne polyurethane sand stabilizer A has a milky semi - transparent appearance, a viscosity of 42 mPa·s at 25 °C, a solid content of 30 wt%, and a pH value of 7. The average particle size of the emulsion is 35 nm, and the storage stability is more than 6 months.

[0040] Example 2: Preparation of Starch-based Waterborne Polyurethane Sand Stabilizer B

[0041] In this example, the molar ratio of raw materials isophorone diisocyanate (IPDI), polytetrahydrofuran diol - 1000 (PTMG - 1000), and 2,2 - dimethylolpropionic acid (DMPA) is 3.2:1:2.

[0042] Add 40.41 g of dehydrated polytetrahydrofuran diol - 1000 (PTMG - 1000) and 28.75 g of isophorone diisocyanate (IPDI) into a detachable four - necked flask equipped with a stirrer and a condenser. Dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). Evacuate and introduce nitrogen. React at 80 °C for 1 hour. Add 10.84 g of dried 2,2 - dimethylolpropionic acid (DMPA), dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL), and react at 80 °C for 2 hours. Add an appropriate amount of solvent to reduce viscosity. Raise the temperature to 95 °C, add 0.80 g of starch (ST) which is 1% (by mass of the system), dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). After reacting for 30 minutes, cool down to 40 °C, add an appropriate amount of solvent to reduce viscosity, add 8.18 g of triethylamine (TEA) and react for 30 minutes. Add 207.84 g of deionized water which is 70% (by mass of the system), shear - emulsify at 2000 r / min at room temperature for 15 minutes. Finally, rotary evaporate to remove the solvent to obtain a milky - white semi - transparent starch - based waterborne polyurethane emulsion, which is the starch - based waterborne polyurethane sand - fixing agent B.

[0043] The starch - based waterborne polyurethane sand - fixing agent B has a milky - white semi - transparent appearance, a viscosity of 45 mPa·s at 25 °C, a solid content of 30 wt%, and a pH value of 7. The average particle size of the emulsion is 37 nm, and the storage stability is greater than 6 months.

[0044] Example 3: Preparation of starch - based waterborne polyurethane sand - fixing agent C

[0045] In this example, the molar ratio of raw materials isophorone diisocyanate (IPDI), polytetrahydrofuran diol - 1000 (PTMG - 1000), and 2,2 - dimethylolpropionic acid (DMPA) is 3.2:1:2.

[0046] Add 40.41 g of dehydrated polytetrahydrofuran diol - 1000 (PTMG - 1000) and 28.75 g of isophorone diisocyanate (IPDI) into a detachable separable four - necked flask equipped with a stirrer and a condenser. Dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). Evacuate and purge with nitrogen, and react at 80 °C for 1 hour. Add 10.84 g of dried 2,2 - dimethylolpropionic acid (DMPA), dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL), and react at 80 °C for 2 hours. Add an appropriate amount of solvent to reduce the viscosity. Raise the temperature to 95 °C, add 1.20 g of starch (ST) which is 1.5% (by mass of the system), dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL), after reacting for 30 minutes, cool down to 40 °C, add an appropriate amount of solvent to reduce the viscosity, add 8.18 g of triethylamine (TEA) and react for 30 minutes, add 207.84 g of deionized water which is 70% (by mass of the system), shear - emulsify at 2000 r / min at room temperature for 15 minutes, and finally remove the solvent by rotary evaporation to obtain a milky - white translucent starch - based aqueous polyurethane emulsion, which is the starch - based aqueous polyurethane sand - fixing agent C.

[0047] The starch - based aqueous polyurethane sand - fixing agent C has a milky - white translucent appearance, a viscosity of 49 mPa·s at 25 °C, a solid content of 30 wt%, and a pH value of 7. The average particle size of the emulsion is 39 nm, and the storage stability is more than 6 months.

[0048] Example 4: Preparation of starch - based aqueous polyurethane sand - fixing agent D

[0049] In this example, the molar ratio of the raw materials isophorone diisocyanate (IPDI), polytetrahydrofuran diol - 1000 (PTMG - 1000), and 2,2 - dimethylolpropionic acid (DMPA) is 3.2:1:2.

[0050] In a detachable separating four-necked flask equipped with a stirrer and a condenser, add 40.41 g of dehydrated polytetrahydrofuran diol-1000 (PTMG-1000) and 28.75 g of isophorone diisocyanate (IPDI). Dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). Evacuate and purge with nitrogen, and react at 80 °C for 1 hour. Add 10.84 g of dried 2,2-dimethylolpropionic acid (DMPA), dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL), and react at 80 °C for 2 hours. Add an appropriate amount of solvent to reduce the viscosity. Raise the temperature to 95 °C, add 1.60 g of starch (ST) which is 2% (by mass of the system), dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). After reacting for 30 minutes, cool down to 40 °C, add an appropriate amount of solvent to reduce the viscosity, add 8.18 g of triethylamine (TEA) and react for 30 minutes. Add 207.84 g of deionized water which is 70% (by mass of the system), and shear and emulsify at 2000 r / min at room temperature for 15 minutes. Finally, remove the solvent by rotary evaporation to obtain a milky semi-transparent starch-based waterborne polyurethane emulsion, which is the starch-based waterborne polyurethane sand stabilizer D.

[0051] The starch-based waterborne polyurethane sand stabilizer D has a milky semi-transparent appearance, a viscosity of 53 mPa·s at 25 °C, a solid content of 30 wt%, and a pH value of 7. The average particle size of the emulsion is 44 nm, and the storage stability is greater than 6 months.

[0052] Example 5: Preparation of starch-based waterborne polyurethane sand stabilizer E

[0053] In this example, the molar ratio of the raw materials isophorone diisocyanate (IPDI), polytetrahydrofuran diol-1000 (PTMG-1000), and 2,2-dimethylolpropionic acid (DMPA) is 3.2:1:2.

[0054] In a detachable separating four-necked flask equipped with a stirrer and a condenser, add 40.41 g of dehydrated polytetrahydrofuran diol-1000 (PTMG-1000) and 28.75 g of isophorone diisocyanate (IPDI). Dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). Evacuate and introduce nitrogen. React at 80 °C for 1 hour. Add 10.84 g of dried 2,2-dimethylolpropionic acid (DMPA). Dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). React at 80 °C for 2 hours. Add an appropriate amount of solvent to reduce the viscosity. Raise the temperature to 95 °C, add 2.00 g of starch (ST) which is 2.5% (by mass of the system). Dropwise add 0.1% (by mass of the system) of the catalyst dibutyltin dilaurate (DBTDL). After reacting for 30 minutes, cool down to 40 °C. Add an appropriate amount of solvent to reduce the viscosity. Add 8.18 g of triethylamine (TEA) and react for 30 minutes. Add 207.84 g of deionized water which is 70% (by mass of the system). Shear and emulsify at room temperature at 2000 r / min for 15 minutes. Finally, remove the solvent by rotary evaporation to obtain a milky semi-transparent starch-based waterborne polyurethane emulsion, which is the starch-based waterborne polyurethane sand-fixing agent E.

[0055] The starch-based waterborne polyurethane sand-fixing agent E has a milky semi-transparent appearance, a viscosity of 57 mPa·s at 25 °C, a solid content of 30 wt%, and a pH value of 7. The average particle size of the emulsion is 47 nm, and the storage stability is greater than 6 months.

[0056] Example 6: Preparation of starch-based waterborne polyurethane sand-fixing agent F

[0057] In this example, the molar ratio of the raw materials isophorone diisocyanate (IPDI), polytetrahydrofuran diol-1000 (PTMG-1000), and 2,2-dimethylolpropionic acid (DMPA) is 3.2:1:2.

[0058] In a detachable separation four-necked flask equipped with a stirrer and a condenser, 40.41 g of dehydrated polytetrahydrofuran diol-1000 (PTMG-1000) and 28.75 g of isophorone diisocyanate (IPDI) were added. Dibutyltin dilaurate (DBTDL), a catalyst accounting for 0.1% of the system mass, was added dropwise. The system was evacuated and purged with nitrogen, and reacted at 80 °C for 1 hour. 10.84 g of 2,2-dimethylolpropionic acid (DMPA) that had been dried was added, dibutyltin dilaurate (DBTDL), a catalyst accounting for 0.1% of the system mass, was added dropwise, and the reaction was carried out at 80 °C for 2 hours. An appropriate amount of solvent was added to reduce the viscosity. The temperature was raised to 95 °C, 2.40 g of starch (ST) accounting for 3% of the system mass was added, dibutyltin dilaurate (DBTDL), a catalyst accounting for 0.1% of the system mass, was added dropwise. After reacting for 30 minutes, the temperature was lowered to 40 °C, an appropriate amount of solvent was added to reduce the viscosity, 8.18 g of triethylamine (TEA) was added and reacted for 30 minutes, 207.84 g of deionized water accounting for 70% of the system mass was added, and shear emulsification was carried out at room temperature at 2000 r / min for 15 minutes. Finally, the solvent was removed by rotary evaporation to obtain a milky translucent starch-based aqueous polyurethane emulsion, which was the starch-based aqueous polyurethane sand-fixing agent F.

[0059] The starch-based aqueous polyurethane sand-fixing agent F is milky translucent in appearance, has a viscosity of 61 mPa·s at 25 °C, a solid content of 30 wt%, and a pH value of 7. The average particle size of the emulsion is 52 nm, and the storage stability is greater than 6 months.

[0060] Example 7: Performance test of starch-based aqueous polyurethane sand-fixing agent

[0061] 1. Test the compressive properties of the starch-based aqueous polyurethane sand-fixing agents A - F prepared in Examples 1 - 6 for solidifying sand:

[0062] The specific test method is as follows: The compressive strength of the starch-based aqueous polyurethane sand-fixing agents A - F for solidifying sand was tested respectively using a 3367 universal testing machine produced by INSTRON Corporation of the United States with reference to the standard of GB / T50123 - 2019 Geotechnical Test Methods. ISO standard sand was selected for the test. The diameter of the soil sample was 3.91 mm, the height was 80 mm, and the dry density was 1.7 g / cm 3 , and a sand-fixing agent accounting for 8% of the sand mass was added, constructed in layers, vibrated and tamped, and its strength was measured after curing at room temperature for 48 h. The compression rate was 2.4 mm / min.

[0063] Table 1 shows the compressive strength data of the starch-based aqueous polyurethane sand-fixing agents A - F prepared in Examples 1 - 6 for solidifying sand. Figure 1Compressive strength curves of sandy soil solidified by starch-based waterborne polyurethane sand fixatives A - F prepared in Examples 1 - 6. It can be seen from the chart that the starch-based waterborne polyurethane sand fixative can effectively solidify sandy soil, has significant compressive strength, excellent sand fixation effect, far higher than the requirement of 1 MPa for the consolidation strength of sandy soil in international standards, and fully meets the needs of engineering applications.

[0064] Table 1 Compressive strength of sandy soil solidified by starch-based waterborne polyurethane sand fixatives A - F prepared in Examples 1 - 6

[0065] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Elastic modulus / Mpa 87.4 106.4 599.0 460.1 481.6 576.8 Compressive strength / Mpa 1.70 2.23 6.52 7.19 8.61 11.18 Compressive strain / % 3.95 4.25 1.75 2.37 3.70 4.01

[0066] 2. Test the permeability of sandy soil solidified by starch-based waterborne polyurethane sand fixatives A - F prepared in Examples 1 - 6:

[0067] The specific test method is as follows: Use a TST-70 type soil permeameter to conduct a constant head permeability test on the sandy soil solidified by starch-based waterborne polyurethane sand fixatives A - F prepared in Examples 1 - 6 respectively according to the standard of GB / T50123 - 2019 Geotechnical Test Methods Standard. The test time is 6 h, and the permeability coefficient K = 2QL / Aht.

[0068] Table 2 shows the permeability coefficients of sandy soil solidified by starch-based waterborne polyurethane sand fixatives A - F prepared in Examples 1 - 6. It can be seen from the table that under room temperature conditions, the permeability performance of this sand fixative is excellent, and it can penetrate to the bottom of the soil permeameter within 6 hours, fully meeting the requirements of spraying construction in practical applications.

[0069] Table 2 Permeability coefficients of sandy soil solidified by starch-based waterborne polyurethane sand fixatives A - F prepared in Examples 1 - 6

[0070] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Infiltration time / h 6 6 6 6 6 6 <![CDATA[Coefficient of permeability K / cms -1 > <![CDATA[6.947×10 -4 > <![CDATA[6.236×10 -4 > <![CDATA[5.831×10 -4 > <![CDATA[5.632×10 -4 > <![CDATA[5.234×10 -4 > <![CDATA[4.976×10 -4 >

[0071] 3. Test the wind erosion resistance of sandy soil solidified by starch-based waterborne polyurethane sand fixatives A - F prepared in Examples 1 - 6:

[0072] The specific test method is as follows: In a sand tray with a diameter of 150 mm, fill a certain mass of standard sand, evenly spray 8% of the sand fixative based on the mass of the sandy soil on the surface of the sand tray, and the covering thickness is 5 mm. Cure for 24 h under room temperature conditions, and place it in a wind erosion simulation experimental device ( Figure 2 ) and continuously erode for 2 h to test the wind erosion resistance. The wind erosion rate Qs = [(m 0 - m c ) / m 0 × 100%, where m 0 is the initial mass of the sandy soil body, and m c is the mass after erosion. The simulation conditions are a strong wind of level 5 and a wind speed of 9.5 m / s.

[0073] Table 3 shows the wind erosion rate data of the sandy soil solidified by the starch-based waterborne polyurethane sand fixatives A to F prepared in Examples 1 to 6. It can be seen from Table 3 that the wind erosion rate of the sandy soil body remains at a low level under the strong wind condition of 9.5 m / s, indicating that the solidified sandy soil has excellent wind erosion resistance and can maintain good stability in a strong wind environment. This characteristic effectively prevents the sandy soil from being blown away by the wind, thus ensuring excellent sand fixation effect.

[0074] Table 3 Sandy soil solidified by the starch-based waterborne polyurethane sand fixatives A to F prepared in Examples 1 to 6

[0075] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 <![CDATA[Wind speed / m / s -1 > 9.5 9.5 9.5 9.5 9.5 9.5 Wind erosion rate / % 3.46 3.28 3.10 2.95 2.74 2.56

[0076] The present invention provides an idea for a starch-based waterborne polyurethane sand fixative and its preparation method. There are many specific methods and ways to implement this technical solution. The above description is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be realized by the prior art.

Claims

1. A method for preparing a starch-based waterborne polyurethane sand-fixing agent, characterized in that: The steps include: S1. The isophorone diisocyanate and polytetrahydrofuran diol -1000 were uniformly mixed, and a catalyst was added to perform a prepolymerization reaction to obtain a prepolymer; S2. Adding 2,2-dimethylol propionic acid to the prepolymer, adding a catalyst and performing a chain extension reaction to obtain a chain extension material; S3. Adding a solvent to reduce viscosity of the chain extender, followed by adding starch and a catalyst to react to obtain a starch-grafted polyurethane; S4. Add solvent to the starch-grafted polyurethane to reduce viscosity, neutralize with triethylamine to form salt, add deionized water for emulsification, and remove the solvent to obtain a starch-based waterborne polyurethane sand-fixing agent.

2. The preparation method according to claim 1, characterized in that: The molar ratio of isophorone diisocyanate, polytetramethylene glycol-1000 and 2,2-dimethylol propionic acid is 3.2:1:

2.

3. The preparation method according to claim 1, characterized in that: The catalyst is dibutyltin dilaurate; the dosage of the dibutyltin dilaurate is 0.01-0.1% of the system mass.

4. The preparation method according to claim 1, characterized in that: The solvent includes any one of acetone, butanone and ethyl acetate; the amount of the solvent used is 15-30% of the system mass.

5. The preparation method according to claim 1, characterized in that: In S1, the prepolymerization reaction has a reaction temperature of 80-90° C. and a reaction time of 1 hour.

6. The preparation method according to claim 1, characterized in that: In S2, the chain extension reaction has a reaction temperature of 80-90° C. and a reaction time of 2 hours.

7. The preparation method according to claim 1, characterized in that: In S3, the amount of starch used is 1-5% of the mass of the system; the reaction temperature is 90-100° C. and the reaction time is 20-40 minutes.

8. The preparation method according to claim 1, characterized in that: In S4, the neutralization degree of the triethylamine during the neutralization and salt formation process is 80-100%; the amount of deionized water used is 65-75% of the system mass.

9. The starch-based waterborne polyurethane sand-fixing agent prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the starch-based waterborne polyurethane sand-fixing agent according to claim 9 in the field of land desertification control.

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