Carbon dioxide-based aqueous polythiurethanes, methods of making and using the same

Abstract

This invention relates to the field of slow-release urea fertilizer technology, and particularly to a carbon dioxide-based waterborne polysulfide urethane, its preparation method, and its application. The carbon dioxide-based waterborne polysulfide urethane of this application is a resin emulsion. Due to its four-arm structure and carbon dioxide-based polyol groups, this emulsion ensures excellent water resistance, improving the slow-release effect of urea. Sulfur is introduced into the soil system through the chemical bonds of the polysulfide urethane. With the action of microorganisms, the sulfur can be converted into sulfur, thus supplementing the soil with sulfur. Compared with slow-release urea prepared using sulfur as a coating agent, this material has a lower sulfur content, avoiding the problem of soil acidification. Furthermore, as a polymer material, it solves the problem of reduced slow-release effect caused by urea breakage during transportation due to sulfur coating.

Description

Technical Field

[0001] This invention relates to the field of slow-release urea fertilizer technology, and in particular to a carbon dioxide-based waterborne polysulfide urethane, its preparation method, and its application. Background Technology

[0002] Chemical fertilizers are an effective way to increase grain yields, potentially increasing them by 40-60% on average. Dr. Stan Chapman, a soil expert at Arkansas State University, discovered that in addition to traditional nitrogen, phosphorus, and potassium fertilizers, soil also needs sulfur, especially for crops like wheat. For every 2700 kg of wheat produced per hectare, at least 11.1 kg of sulfur needs to be absorbed from the soil. Dr. John Havelin, a soil and drought crop expert at Kansas State University, found that sulfur deficiency in wheat causes new leaves to turn yellow, affecting crop growth. Urea, an important nitrogen fertilizer, requires 3-5 days of microbial action in the soil to be gradually absorbed. Rainfall causes urea to dissolve rapidly in water and penetrate deeper into the soil, losing its effectiveness. Therefore, crops require multiple applications of fertilizer during their growth period, resulting in low fertilizer utilization.

[0003] Coating urea with a coating agent to prepare slow-release urea is an important method to improve urea fertilizer efficiency. Mature coating agents include sulfur, wax, and polymers. Among these, sulfur-based slow-release urea is the most representative. It not only replenishes the sulfur content in the soil, but sulfur, as a hydrophobic material, also allows for the slow release of urea, improving fertilizer efficiency. However, sulfur, as a weak inorganic material, makes slow-release urea fertilizers highly susceptible to breakage during transportation, easily losing their slow-release effect. Furthermore, the coating process generates numerous defects such as pores and cracks, reducing the slow-release effect. Additionally, a large amount of the coating agent is entirely sulfur, which, when decomposed by microorganisms in the soil, produces sulfuric acid, leading to soil acidification and damaging soil structure. Therefore, in recent years, more high-molecular-weight polymers have been used as coating agents. The most widely used is the polyurethane system composed of polypropylene glycol and polyisocyanates. Although this solves the problems of slow release and transportation of urea, it cannot provide the sulfur component. Therefore, it is necessary to supplement the soil with sulfur through other means.

[0004] Therefore, in order to meet the needs of practical applications, how to provide a high-performance water-based coating agent with a reasonable sulfur content is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of the existing situation, the present invention provides a carbon dioxide-based waterborne polysulfide urethane, its preparation method, and its application, thereby solving at least one of the above-mentioned technical problems. The technical solution provided by this application is: a carbon dioxide-based waterborne polysulfide urethane having the following structural formula:

[0006] ,in,

[0007] R1 is independently selected from: , , , , , , , ;

[0008] R2 is: Where m = 1~100, n = 1~100;

[0009] R3 is selected independently from: , , , , ;

[0010] R4 is selected independently from: , ,NH3·H2O.

[0011] This application also provides a method for preparing carbon dioxide-based aqueous polysulfide urethane, comprising the following steps:

[0012] Step 1: Under protective atmosphere, add 258.7-470.6g of carbon dioxide-based diol, 83.5-135.2g of diisocyanate, 47.5-51.7g of pentaerythritol tetra(3-mercaptopropionic acid) ester, 0.35-0.51g of catalyst and 13.1-18.5g of dimethylolpropionic acid into a container. Control the temperature at 75-85℃ and react for 1-2 hours to obtain the first reaction solution.

[0013] Step 2: Add 580-720g of acetone and 37.5-88.5g of dithiol compound to the reaction solution from step 1, continue the reaction for 1-2 hours, cool down to 15-35°C, add 3.9-10.5g of neutralizing agent and 548-748.5g of deionized water, and continue stirring for 20-45 minutes to obtain an aqueous emulsion.

[0014] The third step involves placing the aqueous emulsion obtained in the second step at room temperature for 24 hours to remove acetone, thereby obtaining carbon dioxide-based aqueous polysulfide urethane.

[0015] Furthermore, the water content of the carbon dioxide-based diol is less than 300 ppm, the molecular weight is 650-1200, and the carbonate content is 38-50%.

[0016] Further, the diisocyanate is one or more of the following: isophorone diisocyanate, 1,6-hexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophthalic dimethyl diisocyanate, 1,4-cyclohexane diisocyanate, tetramethyl isophthalimide diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, 1,4-cyclohexane dimethyl diisocyanate, and norbornene diisocyanate.

[0017] Furthermore, the catalyst is one or more of dibutyltin diacetate, stannous octate, dibutyltin dilaurate, dioctyltin dilaurate, bismuth octate, and bismuth neodecanoate.

[0018] Furthermore, the neutralizing agent is one or more of triethylamine, ammonia, or N,N-dimethylethanolamine.

[0019] Further, the dithiol compound is one or a mixture of 1,3-benzenedimethylthiol, 1,2-ethanedithiol, 5-bromo-1,3-phenyldithiol, 3,4-toluenedithiophenol, and biphenyl-4,4'-dithiol.

[0020] This application also provides the use of the above-mentioned carbon dioxide-based waterborne polysulfide urethane in the preparation of waterborne coating agents for fertilizers.

[0021] Furthermore, the aqueous coating agent comprises the following components in parts by weight:

[0022] The above-mentioned carbon dioxide-based waterborne polysulfide urethane contains 120-200 parts, color powder 10.5-18.6 parts, waterborne leveling agent 0.3-0.8 parts, waterborne wetting agent 0.4-1.1 parts, waterborne defoamer 0.6-3.5 parts, and waterborne additives 22-45 parts.

[0023] Preferably, the water-based pigment is one of yellow pigment, green pigment, and red pigment;

[0024] Preferably, the water-based leveling agent is one or more of BYK-380N, BYK-381, BYK-307, BYK-341, BYK-345, BYK-346, and BYK-348;

[0025] Preferably, the aqueous wetting agent is one or more of BYK-187, BYK-3400, and BYK-3410;

[0026] Preferably, the water-based defoamer is one or more of BYK-019, BYK-020, BYK-024, BYK-028, and BYK-1730;

[0027] Preferably, the co-solvent is one or more of isopropanol, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol butyl ether, ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, and propylene glycol ethyl ether acetate.

[0028] This application also provides a sustained-release urea, which is prepared by the following method: preheating urea particles with an average particle size of 3-5 mm to not less than 60°C and stirring, then spraying an aqueous coating agent with a weight equivalent to 1-2% of the urea particles onto the urea particles, while simultaneously heating the mixture under stirring to 105-120°C, stirring thoroughly, and then cooling to room temperature to obtain the sustained-release urea.

[0029] The beneficial effects of this application are as follows:

[0030] A water-based carbon dioxide-based polysulfide urethane, its preparation method, and its application in the preparation of water-based coating agents are provided. Sulfur is introduced into the water-based coating agent through a chemical method, which effectively solves the problem of sulfur breakage during transportation caused by sulfur coating agents and better limits the problem of soil acidification caused by excessive sulfur, thus effectively introducing sulfur into the soil.

[0031] The carbon dioxide-based waterborne polysulfide urethane of this application is a resin emulsion. Due to its four-arm structure and carbon dioxide-based polyol groups, this emulsion has excellent water resistance and improves the slow-release effect of urea. Sulfur is introduced into the soil system through the chemical bonds of polysulfide urethane. With the action of microorganisms, the sulfur can be converted into sulfur, which plays a role in replenishing sulfur in the soil. Compared with slow-release urea prepared by using sulfur as a coating agent, this material has a low sulfur content, avoiding the problem of soil acidification. Moreover, as a polymer material, it solves the problem of poor slow-release effect caused by the breakage of urea during transportation due to sulfur coating. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. The drawings described below are some embodiments of the invention, but not all embodiments. Other drawings will be readily available to those skilled in the art based on these drawings without any inventive effort.

[0033] Figure 1 SEM image of urea particles;

[0034] Figure 2 EDS spectrum of urea particles;

[0035] Figure 3 SEM image of an embodiment of the sustained-release urea provided in this application;

[0036] Figure 4 EDS spectrum of an embodiment of the sustained-release urea provided in this application; Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] Example 1 provides a carbon dioxide-based aqueous polysulfide urethane emulsion, the preparation method of which includes the following steps:

[0039] Step 1: Under nitrogen protection, 402.5g of pre-dehydrated carbon dioxide-based diol (molecular weight = 1000, carbonate content = 40%), 111.7g of isophorone diisocyanate, 49.5g of pentaerythritol tetra(3-mercaptopropionic acid) ester, 0.35g of dibutyltin diacetate and 18.5g of dimethylolpropionic acid were added to a three-necked flask. The temperature was controlled at 75℃ and the reaction was carried out for 2 hours.

[0040] Step 2: Add 580g of acetone and 68.2g of 1,3-benzenedimethylthiol to the reaction solution from step 1, and continue the reaction for 1 hour. Cool down to 15°C, add 9.3g of triethylamine and 630g of deionized water, and continue stirring for 20 minutes to obtain an aqueous emulsion.

[0041] The third step is to place the aqueous emulsion obtained in the second step at room temperature for 24 hours, and then remove the acetone under negative pressure to obtain a carbon dioxide-based aqueous polysulfide emulsion.

[0042] Example 2 provides a synthesis of a carbon dioxide-based aqueous polysulfide urethane emulsion, the preparation method of which includes the following steps:

[0043] Step 1: Under nitrogen protection, 318.6g of pre-dehydrated carbon dioxide-based diol (molecular weight = 800, carbonate content = 45%), 135.2g of 4,4'-dicyclohexylmethane diisocyanate, 48.1g of pentaerythritol tetra(3-mercaptopropionic acid) ester, 0.42g of stannous octoate and 16.3g of dimethylolbutyric acid were added to a three-necked flask. The temperature was controlled at 85℃, and the reaction was carried out for 1 hour.

[0044] Step 2: Add 720g of acetone and 37.5g of 1,2-ethylenedithiol to the reaction solution from step 1, and continue the reaction for 2 hours. Cool down to 35°C, add 7.9g of N,N-dimethylethanolamine and 548g of deionized water, and continue stirring for 45 minutes to obtain an aqueous emulsion.

[0045] The third step is to place the aqueous emulsion obtained in the second step at room temperature for 24 hours, and then remove the acetone under negative pressure to obtain a carbon dioxide-based aqueous polysulfide emulsion.

[0046] Example 3 provides a synthesis of a carbon dioxide-based aqueous polysulfide urethane emulsion, the preparation method of which includes the following steps:

[0047] Step 1: Under nitrogen protection, 470.6g of pre-dehydrated carbon dioxide-based diol (molecular weight = 1200, carbonate content = 38%), 87.5g of 1,6-hexamethylene diisocyanate, 50.4g of pentaerythritol tetra(3-mercaptopropionic acid) ester, 0.38g of dibutyltin dilaurate, and 17.4g of dimethylolpropionic acid were added to a three-necked flask. The temperature was controlled at 80℃, and the reaction was carried out for 1.5 hours.

[0048] Step 2: Add 620g of acetone and 88.5g of 5-bromo-1,3-phenyldithiol to the reaction solution from step 1, and continue the reaction for 1.5 hours. Cool down to 25°C, add 10.5g of triethylamine and 748.5g of deionized water, and continue stirring for 30 minutes to obtain an aqueous emulsion.

[0049] The third step is to place the aqueous emulsion obtained in the second step at room temperature for 24 hours, and then remove the acetone under negative pressure to obtain a carbon dioxide-based aqueous polysulfide emulsion.

[0050] Example 4 provides a synthesis of a carbon dioxide-based aqueous polysulfide urethane emulsion, the preparation method of which includes the following steps:

[0051] Step 1: Under nitrogen protection, 258.7g of pre-dehydrated carbon dioxide-based diol (molecular weight = 650, carbonate content = 50%), 83.5g of 1,4-cyclohexane diisocyanate, 47.5g of pentaerythritol tetra(3-mercaptopropionic acid) ester, 0.47g of dioctyltin dilaurate, and 13.1g of dimethylolbutyric acid were added to a three-necked flask. The temperature was controlled at 82℃, and the reaction was carried out for 1.5 hours.

[0052] Step 2: Add 650g of acetone and 62.7g of 3,4-toluenedithiophenol to the reaction solution from step 1, and continue the reaction for 1 hour. Cool down to 28°C, add 3.9g of sodium hydroxide and 670g of deionized water, and continue stirring for 35 minutes to obtain an aqueous emulsion.

[0053] The third step is to place the aqueous emulsion obtained in the second step at room temperature for 24 hours, and then remove the acetone under negative pressure to obtain a carbon dioxide-based aqueous polysulfide emulsion.

[0054] Example 5 provides a synthesis of a carbon dioxide-based aqueous polysulfide urethane emulsion, the preparation method of which includes the following steps:

[0055] Step 1: Under nitrogen protection, add 400.5g of pre-dehydrated carbon dioxide-based diol (molecular weight = 1030, carbonate content = 45%), 95.3g of m-phenylenedimethyl diisocyanate, 51.7g of pentaerythritol tetra(3-mercaptopropionic acid) ester, 0.51g of bismuth octanoate, and 17.8g of dimethylolpropionic acid to a three-necked flask. The temperature is controlled at 75-85℃, and the reaction is carried out for 1-2 hours.

[0056] Step 2: Add 650g of acetone and 87.5g of biphenyl-4,4'-dithiol to the reaction solution from step 1, and continue the reaction for 1 hour. Cool down to 32°C, add 7.5g of N,N-dimethylethanolamine and 735g of deionized water, and continue stirring for 35 minutes to obtain an aqueous emulsion.

[0057] The third step is to place the aqueous emulsion obtained in the second step at room temperature for 24 hours, and then remove the acetone under negative pressure to obtain a carbon dioxide-based aqueous polysulfide emulsion.

[0058] Example 6 provides an aqueous coating agent, the composition of which is shown in Table 1.

[0059] Table 1. Dosage of each component in the water-based coating agent

[0060]

[0061] The preparation method of the aqueous coating agent is as follows:

[0062] Step 1: At room temperature, add pigment, water-based defoamer, water-based additives and water-based wetting agent to the grinding tank, and grind for 1 hour to grind the particle size to below 1 micrometer to obtain water-based slurry;

[0063] The second step is to introduce the water-based slurry into a high-speed disperser, add carbon dioxide-based water-based polysulfide urethane emulsion and water-based leveling agent, stir for 15 minutes, and filter with a 100-mesh filter to obtain the water-based coating agent.

[0064] Example 7 provides a slow-release urea, prepared by adding 3000g of urea granules with an average particle size of 3-5mm into a 5L rotary drum, preheating to 70°C for 8 minutes, and spraying 40g of the aqueous coating agent obtained in Example 6 onto the urea granules while continuously stirring in the drum. Simultaneously, the fertilizer in the drum is heated to 110°C, the rotation speed is adjusted to 150 rpm, and stirring continues for 15 minutes. The temperature is then reduced to room temperature, and the product is discharged to obtain slow-release urea. The SEM image of the urea granules is attached. Figure 1 EDS spectrum is attached. Figure 2 The elemental analysis results are shown in Table 3 below:

[0065] Table 3. Elemental Analysis of Urea Particles

[0066]

[0067] The SEM image of the sustained-release urea 1 prepared further using the aqueous coating agent 1 prepared in Example 1 is attached. Figure 3 EDS spectrum is attached. Figure 4 The elemental analysis results are shown in Table 4 below:

[0068] Table 4. Elemental Analysis of Sustained-Release Urea

[0069]

[0070] Comparison of the SEM spectra, EDS spectra, and elemental analysis table of urea particles and sustained-release urea 1 shows that the aqueous coating agent provided in this application can form a coating that is basically free of pores and cracks, and can coat urea particles to the point that N element cannot be detected in the EDS spectra.

[0071] The nutrient release rate of slow-release fertilizer can reflect the performance of water-based coating agents. The test method is as follows:

[0072] Initial nutrient release rate: The mass fraction of nitrogen released from the prepared urea slow-release fertilizer after 24 hours of extraction in still water at 25℃, relative to the total nitrogen content.

[0073] Cumulative nutrient release rate: The mass fraction of nitrogen released by urea slow-release fertilizer in still water at 25℃ over a certain period of time, relative to the total nitrogen content.

[0074] Nutrient release period: The time required for urea slow-release fertilizer to reach a cumulative nutrient release rate of 80% when extracted in still water at 25℃.

[0075] The test results are shown in Table 2.

[0076] Table 2. Performance Tests of Water-Based Coating Agents

[0077]

[0078] As can be seen from the results in Table 2, the coating agents prepared in the embodiments of the present invention have an initial nutrient release rate of less than 15%, meeting the requirements of GB / T23348-2009. All of them meet the requirement of a release rate of less than 85% within 90 days. Moreover, the coating agents prepared in Examples 1 and 2 can achieve nutrient release for 120 days. The aqueous coating agent provided by the present invention has excellent sustained-release effect due to the water resistance of the carbon dioxide-based polyol and its four-arm internal cross-linking structure.

[0079] The above-described contents can be implemented individually or in various combinations, and these variations are all within the protection scope of this invention.

[0080] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0081] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered within the scope of protection of the present invention.

Claims

1. A carbon dioxide-based waterborne polysulfuron, characterized in that, It has the following structural formula: ； Wherein, R1 is independently selected from: ； ； R2 is: ； Where m = 1 to 100, n = 1 to 100; R3 is independently selected from: ； ； R4 is selected independently from: NH3.H2O.

2. A method for preparing carbon dioxide-based aqueous polysulfuron as described in claim 1, characterized in that, Includes the following steps: Step 1: Under protective atmosphere, add 258.7-470.6g of carbon dioxide-based diol, 83.5-135.2g of diisocyanate, 47.5-51.7g of pentaerythritol tetra(3-mercaptopropionic acid) ester, 0.35-0.51g of catalyst and 13.1-18.5g of dimethylolpropionic acid into a container. Control the temperature at 75-85℃ and react for 1-2 hours to obtain the first reaction solution. Step 2: Add 580-720g of acetone and 37.5-88.5g of dithiol compound to the first reaction solution, continue the reaction for 1-2 hours, cool down to 15-35℃, add 3.9-10.5g of neutralizing agent and 548-748.5g of deionized water, and continue stirring for 20-45 minutes to obtain an aqueous emulsion; Step 3: Place the aqueous emulsion obtained in Step 2 at room temperature for 24 hours to remove acetone and obtain the carbon dioxide-based aqueous polysulfide urethane.

3. The preparation method according to claim 2, characterized in that, The carbon dioxide-based diol has a water content of less than 300 ppm, a molecular weight of 650-1200, and a carbonate content of 38-50%.

4. The preparation method according to claim 2, characterized in that, The diisocyanate is one or more selected from isophorone diisocyanate, 1,6-hexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophthalic diisocyanate, 1,4-cyclohexane diisocyanate, tetramethyl isophthalimide diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, 1,4-cyclohexane dimethyl diisocyanate, and norbornene diisocyanate.

5. The preparation method according to claim 2, characterized in that, The catalyst is one or more of dibutyltin diacetate, stannous octate, dibutyltin dilaurate, dioctyltin dilaurate, bismuth octate, and bismuth neodecanoate.

6. The preparation method according to claim 2, characterized in that, The neutralizing agent is one or more of triethylamine, ammonia, or N,N-dimethylethanolamine.

7. The preparation method according to claim 2, characterized in that, The dithiol compound is one or a mixture of 1,3-benzenedimethylthiol, 1,2-ethanedithiol, 5-bromo-1,3-phenyldithiol, 3,4-toluenedithiophenol, and biphenyl-4,4'-dithiol.

8. The use of the carbon dioxide-based waterborne polysulfide urethane according to claim 1 in the preparation of a waterborne coating agent for fertilizers.

9. The application according to claim 8, characterized in that, The aqueous coating agent comprises the following components in parts by weight: The carbon dioxide-based waterborne polysulfide urethane of claim 1 comprises 120-200 parts, color powder 10.5-18.6 parts, waterborne leveling agent 0.3-0.8 parts, waterborne wetting agent 0.4-1.1 parts, waterborne defoamer 0.6-3.5 parts, and waterborne additives 22-45 parts.

10. A slow release urea characterized in that, The urea is prepared by the following method: urea particles with an average particle size of 3-5 mm are preheated to a temperature of not less than 60°C and stirred. Then, an aqueous coating agent of claim 9, with a weight equivalent to 1-2% of the urea particles, is sprayed onto the urea particles. At the same time, the mixture under stirring is heated to 105-120°C. After thorough stirring, the mixture is cooled to room temperature to obtain the slow-release urea.

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