Carbon dioxide-based water-based polythionocarbamate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of slow-release urea fertilizers, in particular to carbon dioxide-based water-based polythionocarbamate as well as a preparation method and application thereof. The carbon dioxide-based water-based polythionocarbamate is a resin emulsion, due to a four-arm structure and a carbon dioxide-based polyol group, it is guaranteed that the emulsion has excellent water resistance, the slow release effect of urea is improved, sulfur elements are introduced into a soil system through chemical bonds of the polythionocarbamate, and the slow release effect of urea is improved along with the action of microorganisms. Compared with the slow-release urea prepared by taking sulfur as a coating agent component, the slow-release urea prepared by taking the sulfur as the coating agent component has the advantages that the content of the sulfur in the slow-release urea is small, the problem of soil acidification is avoided, and the slow-release urea prepared by taking the sulfur as the coating agent component has a good slow-release effect. The problem that the slow release effect becomes poor due to the fact that the urea is broken in the transportation process due to the fact that the urea is coated with sulfur is solved.

Description

Technical Field

[0001] The invention relates to the technical field of slow-release urea fertilizers, and in particular to a carbon dioxide-based aqueous polythiourethane and a preparation method and application thereof. Background Art

[0002] Chemical fertilizer is an effective way to increase grain production, which can increase grain production by an average of 40-60%. Dr. Stan Chapman, a soil expert at Arkansas State University, found that in addition to traditional nitrogen fertilizers, phosphorus and potassium fertilizers, the soil also needs to supplement sulfur, especially for wheat crops. To produce 2,700 kilograms of wheat per hectare of land, at least 11.1 kilograms of sulfur must be absorbed from the soil. Dr. John Havlin, a soil fertilizer and drought crop expert at Kansas State University, found that if wheat lacks sulfur, new leaves will turn yellow, affecting the growth of crops. Urea, as an important nitrogen fertilizer, needs to be gradually absorbed by microorganisms in the soil for 3-5 days. Once it rains, the urea will quickly dissolve into the water and enter the deep soil layer, thus losing its fertilizer effect. Therefore, multiple fertilizations are required during the growth of crops, and the utilization rate of chemical fertilizers is low.

[0003] The slow-release urea prepared by coating the surface of urea with a layer of coating agent is an important method to improve the fertilizer efficiency of urea. Mature coating agents include materials such as sulfur, wax and polymers. The most representative one is the slow-release urea prepared by using sulfur as a coating agent, which can not only supplement the sulfur content in the soil, but also sulfur, as a hydrophobic material, can slowly release urea, thereby improving the fertilizer efficiency. However, sulfur, as an inorganic material without strength, is very easy to break during transportation and loses the slow-release effect. In addition, a large number of holes, cracks and other defects are generated during the coating process, which reduces the slow-release effect. Moreover, a large number of coating agents are all sulfur, which produces sulfuric acid after being decomposed by microorganisms in the soil, leading to soil acidification and destruction of soil structure. Therefore, in recent years, more coating agent materials are high molecular polymers, and the most widely used is the polyurethane system composed of polypropylene glycol and polyisocyanate. Although the problem of slow-release and transportation of urea is solved, there is no way to provide sulfur components, so it is necessary to supplement sulfur to the soil through other ways.

[0004] Therefore, in order to meet the needs of practical applications, how to provide an aqueous coating agent with good performance and reasonable sulfur content is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] In view of the existing phenomenon, the present invention provides a carbon dioxide-based water-based polythiourethane and a preparation method and application thereof, which at least solves one of the above technical problems. The technical solution provided in the present application is: a carbon dioxide-based water-based polythiourethane having the following structural formula:

[0006] in,

[0007] R 1 Independently selected from:

[0008] R 2 for: Wherein m=1-100, n=1-100;

[0009] R 3 Independently selected from:

[0010] R 4 Independently selected from: NH 3 ·H 2 O.

[0011] The present application also provides a method for preparing a carbon dioxide-based water-based polythiourethane, comprising the following steps:

[0012] Step 1: Under protective gas protection, 258.7-470.6 g of carbon dioxide-based diol, 83.5-135.2 g of diisocyanate, 47.5-51.7 g of pentaerythritol tetrakis (3-mercaptopropionic acid) ester, 0.35-0.51 g of catalyst and 13.1-18.5 g of dimethylol propionic acid are added into a container, the temperature is controlled at 75-85° C., and the reaction is carried out for 1-2 hours to obtain a first reaction solution;

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

[0014] Step 3: Place the aqueous emulsion obtained in step 2 at room temperature for 24 hours to remove acetone to obtain carbon dioxide-based aqueous polythiourethane.

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

[0016] Furthermore, the diisocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, meta-xylylene diisocyanate, 1,4-cyclohexane diisocyanate, tetramethyl meta-xylylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, 1,4-cyclohexane dimethyl diisocyanate, and norbornane diisocyanate.

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

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

[0019] Furthermore, the dithiol compound is a mixture of one or more of 1,3-benzenedithiol, 1,2-ethanedithiol, 5-bromo-1,3-phenyldithiol, 3,4-toluenedithiol, and biphenyl-4,4'-dithiol.

[0020] The present application also provides a use of the above-mentioned carbon dioxide-based aqueous polythiourethane in the preparation of an aqueous coating agent for fertilizers.

[0021] Further, the aqueous coating agent includes the following components in parts by weight:

[0022] The above-mentioned carbon dioxide-based water-based polythiourethane comprises 120-200 parts, color powder comprises 10.5-18.6 parts, water-based leveling agent comprises 0.3-0.8 parts, water-based wetting agent comprises 0.4-1.1 parts, water-based defoaming agent comprises 0.6-3.5 parts, and water-based auxiliary agent comprises 22-45 parts.

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

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

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

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

[0027] Preferably, the cosolvent 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] The present application also provides a slow-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 the aqueous coating agent of claim 9, which is equivalent to 1-2% of the weight of the urea particles, onto the urea particles, and at the same time heating the stirred mixture to 105-120° C., and cooling to room temperature after sufficient stirring to obtain the slow-release urea.

[0029] The beneficial effects of this application are:

[0030] Provided are an aqueous carbon dioxide-based polythiocarbazate, a preparation method thereof and an application thereof in the preparation of an aqueous coating agent. Sulfur is introduced into the aqueous coating agent by a chemical method, thereby effectively solving the problem of sulfur breakage during transportation caused by the sulfur coating agent solution and better limiting the problem of soil acidification caused by excessive sulfur, thereby effectively introducing sulfur into the soil.

[0031] The carbon dioxide-based water-based polythiourethane of the present application is a resin emulsion. Due to its four-arm structure and carbon dioxide-based polyol groups, the emulsion is guaranteed to have excellent water resistance and improve the sustained-release effect of urea. The sulfur element is introduced into the soil system through the chemical bonds of the polythiourethane. With the action of microorganisms, the sulfur element can be converted into sulfur, which plays a role in supplementing sulfur to the soil. Compared with the preparation of sustained-release urea using sulfur as a coating agent component, the sulfur element content in the material is small, avoiding the problem of soil acidification. As a polymer material, the problem of poor sustained-release effect caused by the breakage of urea during transportation due to sulfur-coated urea is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are incorporated into and constitute a part of the specification, illustrate embodiments of the present invention and are used together with the description to explain the principles of the present invention. The drawings described below are some embodiments of the present invention, but not all embodiments. For those of ordinary skill in the art, other drawings can be obtained from these drawings without creative work.

[0033] Figure 1 is the SEM spectrum of urea granules;

[0034] Figure 2 is the EDS spectrum of urea particles;

[0035] Figure 3 This is a SEM spectrum of an embodiment of the slow-release urea provided in this application;

[0036] Figure 4 An EDS spectrum of an embodiment of the slow-release urea provided in this application; DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Embodiment 1 provides a carbon dioxide-based aqueous polythiourethane emulsion, and its preparation method comprises the following steps:

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

[0040] Step 2: Add 580 g acetone and 68.2 g 1,3-benzenedimethanethiol to the reaction solution of step 1, and continue the reaction for 1 hour. Cool down to 15°C, add 9.3 g triethylamine and 630 g 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 polythiourethane emulsion.

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

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

[0044] Step 2: Add 720 g acetone and 37.5 g 1,2-ethanedithiol to the reaction solution of step 1, and continue the reaction for 2 hours. Cool down to 35°C, add 7.9 g N,N-dimethylethanolamine and 548 g 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 polythiourethane emulsion.

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

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

[0048] Step 2: Add 620 g acetone and 88.5 g 5-bromo-1,3-phenyldithiol to the reaction solution of step 1, and continue the reaction for 1.5 hours. Cool to 25°C, add 10.5 g triethylamine and 748.5 g 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 polythiourethane emulsion.

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

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

[0052] Step 2: Add 650g acetone and 62.7g 3,4-toluenedithiophenol to the reaction solution of step 1, and continue to react for 1 hour. Cool to 28°C, add 3.9g sodium hydroxide and 670g 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 polythiourethane emulsion.

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

[0055] Step 1: Under nitrogen protection, 400.5 g of pre-dehydrated carbon dioxide-based diol (molecular weight = 1030, carbonate content = 45%), 95.3 g of m-xylylene diisocyanate, 51.7 g of pentaerythritol tetrakis (3-mercaptopropionic acid) ester, 0.51 g of bismuth octanoate and 17.8 g of dimethylol propionic acid were added to a three-necked flask, the temperature was controlled at 75-85° C., and the reaction was carried out for 1-2 hours;

[0056] Step 2: Add 650g acetone and 87.5g biphenyl-4,4'-dithiol to the reaction solution of step 1, and continue to react for 1 hour. Cool to 32°C, add 7.5g N,N-dimethylethanolamine and 735g 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 polythiourethane 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 of aqueous coating agent

[0060]

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

[0062] Step 1: Add pigment, aqueous defoamer, aqueous additive and aqueous wetting agent into a grinding tank at room temperature, sand grind for 1 hour, grind the particle size to less than 1 micron, and obtain aqueous slurry;

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

[0064] Example 7 provides a slow-release urea, the preparation method of which is to add 3000g of urea granules with an average particle size of 3-5mm into a 5L drum, preheat to 70°C, the preheating time is 8min, and while the drum is continuously stirred, 40g of the aqueous coating agent obtained in Example 6 is sprayed on the urea granules in the drum, and at the same time, the fertilizer in the drum is heated to 110°C, the speed is adjusted to 150 rpm, stirring is continued for 15min, the temperature is reduced to room temperature, and the material is discharged to obtain slow-release urea. The SEM spectrum of the urea granules is shown in the attached figure. Figure 1 , EDS spectrum as attached Figure 2 , the element analysis results are shown in Table 3 below:

[0065] Table 3. Elemental analysis of urea granules

[0066] element Line Type Wt% Wt%Sigma At% C K-line system 23.09 0.53 26.98 N K-line system 44.58 0.78 44.66 O K-line system 32.34 0.65 28.36 Au 0.00 0.00 Total amount: 100.00 100.00

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

[0068] Table 4. Elemental analysis of slow-release urea 1

[0069] element Line Type Wt% Wt%Sigma At% C K-line system 80.39 0.32 84.52 N K-line system 0.00 2.06 0.00 O K-line system 19.61 0.32 15.48 Au 0.00 0.00 Total amount: 100.00 100.00

[0070] By comparing the SEM spectra, EDS spectra and elemental analysis table of urea granules and slow-release urea 1, it can be seen that the aqueous coating agent provided in the present application can form a coating with basically no holes or cracks, and can coat the urea granules until the N element cannot be detected in the EDS spectrum.

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

[0072] Initial nutrient release rate: The mass fraction of nitrogen released when the prepared urea slow-release fertilizer is immersed in static water at 25°C for 24 hours to the total nitrogen.

[0073] Cumulative nutrient release rate: The mass fraction of the total nitrogen released by urea slow-release fertilizer in 25°C static water over a certain period of time

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

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

[0076] Table 2. Performance test of water-based coating agents

[0077]

[0078]

[0079] From the results in Table 2, it can be seen that the coating agent prepared in the embodiment of the present invention has an initial nutrient release of less than 15%, which meets the requirements of GB / T23348-2009, and all meet the requirements of a release rate of less than 85% within 90 days, and the coating agents prepared in Examples 1 and 2 can achieve 120 days of nutrient release. The water-based coating agent provided by the present invention has an excellent sustained-release effect because of the water resistance of the carbon dioxide-based polyol and the four-arm internal cross-linking structure.

[0080] The contents described above may be implemented individually or in combination in various ways, and these variations are all within the protection scope of the present invention.

[0081] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements.

[0082] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementation modes, and it cannot be determined that the specific embodiments of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A carbon dioxide-based water-based polythiourethane, characterized in that: Has the following structural formula: in, R1 is independently selected from: R2 is: Wherein m=1-100, n=1-100; R3 is independently selected from: R4 is independently selected from: NH3·H2O.

2. A method for preparing a carbon dioxide-based water-based polythiourethane, characterized in that: The following steps are involved: Step 1: Under protective gas protection, 258.7-470.6 g of carbon dioxide-based diol, 83.5-135.2 g of diisocyanate, 47.5-51.7 g of pentaerythritol tetrakis (3-mercaptopropionic acid) ester, 0.35-0.51 g of catalyst and 13.1-18.5 g of dimethylol propionic acid are added into a container, the temperature is controlled at 75-85° C., and the reaction is carried out for 1-2 hours to obtain a first reaction solution; Step 2: add 580-720 g of acetone and 37.5-88.5 g of dithiol compound to the reaction solution of the first step, continue to react for 1-2 hours, then cool to 15-35° C., add 3.9-10.5 g of neutralizer and 548-748.5 g of deionized water, continue stirring for 20-45 min, and obtain an aqueous emulsion; The third step is to place the aqueous emulsion obtained in the second step at room temperature for 24 hours, remove acetone, and obtain the carbon dioxide-based aqueous polythiourethane.

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

4. The preparation method according to claim 2, characterized in that: The diisocyanate is one or more of isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, meta-xylylene diisocyanate, 1,4-cyclohexane diisocyanate, tetramethyl meta-xylylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, 1,4-cyclohexane dimethyl diisocyanate, and norbornane diisocyanate.

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

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

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

8. Use of the carbon dioxide-based aqueous polythiourethane according to claim 1 in the preparation of an aqueous coating agent for fertilizers.

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

10. A slow-release urea, characterized in that: The slow-release urea 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 the aqueous coating agent according to claim 9, which is equivalent to 1-2% of the weight of the urea particles, onto the urea particles, and simultaneously heating the stirred mixture to 105-120° C., stirring thoroughly and then cooling to room temperature to obtain the slow-release urea.

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