AQUEOUS SUSPENSION COMPOSITIONS CONTAINING N-(N-BUTYL) THIOPHOSPHORIC TRIAMIDE AND DICYANDIAMIDE

Abstract

The present subject matter relates generally to stable and homogeneous aqueous suspension compositions comprising urea, water, a suspension agent, urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) and nitrification inhibitor dicyandiamide (DCD), and to methods of preparing and using such compositions.

Claims

1. A suspension composition comprising urea, water, a suspension agent, N-(n-butyl) thiophosphoric triamide (NBPT), dicyandiamide (DCD), and an optional dye.

2. The suspension composition of claim 1, wherein the weight percentage of urea is 5-40%, the weight percentage of water is 15-40%, the weight percentage of NBPT is 0.5-20%, the weight percentage of DCD is 10-60%, the weight percentage of the suspension agent is 0.01-10%, and the weight percentage of the optional dye is 0-5%.

3. The suspension composition of claim 2, wherein the suspension agent is selected from the group consisting of dextran, gellan, rhamsan, guar, xanthan gums, tragacanth gum, hydroxymethylcellulose, hydroxyethylcellulose, microcrystalline cellulose, polyvinyl alcohols, polyvinyl acetates and cross-linked polyacrylates.

4. The suspension composition of claim 3, wherein the suspension agent is xanthan gum.

5. The suspension composition of claim 1, wherein the suspension stays substantially homogeneous for at least 30 days.

6. The suspension composition of claim 2, wherein the suspension stays substantially homogeneous for at least 30 days.

7. The suspension composition of claim 3, wherein the suspension stays substantially homogeneous for at least 30 days.

8. The suspension composition of claim 4, wherein the suspension stays substantially homogeneous for at least 30 days.

9. The suspension composition of claim 1, wherein 0.1% to 7.5% of the NBPT by weight is solubilized in the aqueous suspension.

10. The suspension composition of claim 2, wherein 0.1% to 7.5% of the NBPT by weight is solubilized in the aqueous suspension.

11. The suspension composition of claim 3, wherein 0.1% to 7.5% of the NBPT by weight is solubilized in the aqueous suspension.

12. The suspension composition of claim 4, wherein 0.1% to 7.5% of the NBPT by weight is solubilized in the aqueous suspension.

13. The suspension composition of claim 1, wherein 0.1% to 7.5% of the DCD by weight is solubilized in the aqueous suspension.

14. The suspension composition of claim 2, wherein 0.1% to 7.5% of the DCD by weight is solubilized in the aqueous suspension.

15. The suspension composition of claim 3, wherein 0.1% to 7.5% of the DCD by weight is solubilized in the aqueous suspension.

16. The suspension composition of claim 4, wherein 0.1% to 7.5% of the DCD by weight is solubilized in the aqueous suspension.

17. A method of making the suspension composition of claim 1 by blending urea, water, a suspension agent, N-(n-butyl) thiophosphoric triamide (NBPT), dicyandiamide (DCD), and the optional dye to form a homogeneous suspension.

18. A method of making a urea-containing fertilizer composition by contacting the suspension composition of claim 1 with molten urea.

19. A method of making a urea-containing fertilizer composition by contacting the suspension composition of claim 2 with molten urea.

20. A method of making a urea-containing fertilizer composition by contacting the suspension composition of claim 3 with molten urea.

21. A method of making a urea-containing fertilizer composition by contacting the suspension composition of claim 4 with molten urea.

22. The suspension composition of claim 1 further comprising a biocide.

23. The suspension composition of claim 2 further comprising a biocide.

24. The suspension composition of claim 3 further comprising a biocide.

25. The suspension composition of claim 4 further comprising a biocide.

Description

DETAILED DESCRIPTION OF THE DISCLOSURE

[0017] As disclosed herein, stable and homogeneous aqueous suspension compositions comprising urea, water, a suspension agent, N-(n-butyl) thiophosphoric triamide (NBPT), dicyandiamide (DCD), an optional dye, and methods of preparing and using such compositions are provided.

[0018] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art.

[0019] The term suspension in present disclosure means a heterogeneous mixture comprising both solid particles and a liquid carrier. The term homogeneous aqueous suspension generally means that when dividing the volume of the whole suspension in half, the substantially same amount of materials are suspended in both halves of the suspension compositions. The term substantially same amount is not absolute and may include up to 10% difference. For example, when the whole suspension is divided into two halves, a specific ingredient may have 45 percent in one half and the remaining 55% in the other half.

[0020] The term stable in present disclosure means both the chemical and physical stabilities. For physical stability, it means that the suspension stays substantially homogeneous for at least 14 days, including up to about 6 months, or can be easily returned to a suspension by agitation.

[0021] In the present disclosure, most of NBPT and DCD are in solid form in the suspension, however, part of NBPT and DCD may solubilize in water. The water solubility of NBPT is 4.310.sup.3 g/mL at 25 C. The water solubility of DCD is 4.1310.sup.2 g/mL. The actual solubility of NBPT and DCD in the suspension compositions of the present disclosure may vary and may not be the same as their individual water solubility.

[0022] The suspension composition can provide an extended period of stability to maintain as a substantially homogeneous suspension. Because the suspension composition comprises both NBPT and DCD, it only requires one single introduction of the suspension composition into a molten urea to make a substantially homogeneous urea fertilizer comprising both NBPT and DCD. This process is more economic and more advantageous since it avoids the use of polar and high boiling point organic solvents such as NMP to dissolve NBPT.

[0023] In one embodiment, the present disclosure provides a stable and homogeneous aqueous suspension composition comprising urea, water, a suspension agent, N-(n-butyl) thiophosphoric triamide (NBPT), dicyandiamide (DCD), and an optional dye.

[0024] In one aspect, the suspension agent in the present disclosure is selected from the group consisting of dextran, gellan, rhamsan, guar, xanthan gums, tragacanth gum, hydroxymethylcellulose, hydroxyethylcellulose, microcrystalline cellulose, polyvinyl alcohols, polyvinyl acetates and cross-linked polyacrylates. In one aspect, a preferred suspension agent is xanthan gums.

[0025] In one aspect, the optional dye in the present disclosure may be any commonly used dye including food dyes that may be used to provide visual evidence of the uniformity of the composition. Examples of dyes suitable in the present disclosure include but are not limited to FD&C Blue No. 1, FD&C Blue No. 1, FD&C Green No. 3, FD&C Yellow No. 5, FD&C Red No. 3, FD&C Red No. 40, FD&C Yellow No. 6, and AGROTAIN ULTRA green dye, or a combination thereof.

[0026] In one aspect, the aqueous suspension composition in the present disclosure may further comprise a biocide. Examples of biocides include Proxel GXL biocide, Koralone biocide, and Bardac biocide.

[0027] In one aspect, the weight percentage range of NBPT in the aqueous suspension composition is 0.01% to 40% by weight, including 0.5% to 30% by weight, 1.0% to 20% by weight, and 1.0% to 10% by weight. In another aspect, the weight percentage range of NBPT is 1.0% to 10% by weight, including 1.0% to 5.0% by weight, 2.0% to 5.0% by weight, and 3.0% to 5.0% by weight. In one aspect, the weight percentage range of DCD in the aqueous suspension composition is 10% to 70% by weight, including 20% to 60% by weight, 20% to 50% by weight, and 30% to 50% by weight. In one aspect, the weight percentage range of urea in the aqueous suspension composition is 10% to 40% by weight, including 15% to 30% by weight and 20% to 25% by weight. In one aspect, the weight percentage range of a suspension agent in the aqueous suspension composition is 0.01% to 10% by weight, including 0.05% to 5% by weight, 0.10% to 3% by weight, and 0.15% to 1% by weight. In one aspect, the weight percentage range of a dye in the total aqueous suspension composition is 0.001-5% by weight, including 0.02% to 2% by weight, and 0.05% to 1% by weight.

[0028] In one aspect, 0.01% to 10% of the DCD by weight is solubilized in the aqueous suspension of the present disclosure, including 0.1% to 7.5% by weight and 1.0% to 5.0% by weight. In one aspect, 0.01% to 10% of the NBPT by weight is solubilized in the aqueous suspension of the present disclosure, including 0.1% to 7.5% by weight and 1.0% to 5.0% by weight.

[0029] In another aspect, the aqueous suspension composition can comprise 0.01% to 40% by weight of NBPT and 10% to 70% by weight of DCD, wherein 0.01% to 10% by weight of the DCD is solubilized in the aqueous suspension and 0.01% to 10% by weight of the NBPT is solubilized in the aqueous suspension. Further, the NBPT in the above aqueous suspension can by solubilized in an amount from 0.1% to 7.5% by weight. Also, the DCD in the above aqueous suspension can be solubilized in an amount from 0.1% to 7.5% by weight.

[0030] In a further aspect, the aqueous suspension composition can comprise 1.0% to 20% by weight of NBPT and 20% to 50% by weight of DCD, wherein 0.01% to 10% by weight of the DCD is solubilized in the aqueous suspension and 0.01% to 10% by weight of the NBPT is solubilized in the aqueous suspension.

Example 1. Aqueous Suspension Composition #1

[0031]

TABLE-US-00001 Ingredient Weight Percentage g/L DCD G Grade 46.34% 561.9 NBPT Tech Grade 3.35% 40.7 Powder Blue Dye 0.09% 1.2 Xanthan Gum 0.18% 2.4 Urea 21.75% 264.6 Water 28.29% 343.8

Method of Making SlurryBasic Process

[0032] Liquid carrier (water and urea) are added to a mixing vessel and mixed, while xanthan gum is slowly added. The xanthan gum and liquid carrier mixture is sampled at various timepoints throughout the process for viscosity plateau to ensure full saturation of the xanthan gum into the liquid carrier. Once full saturation occurs, the NBPT, DCD and optional dye are added to the mixing vessel and mixing continues until the slurry is homogenous (10-15 additional minutes). Optionally, a biocide can be added to the slurry after homogeneity is reached. If added, the slurry is mixed for an additional 5 minutes.

Example 2Method of Making Aqueous Suspension Composition #2

[0033] Aqueous Suspension Composition #2 contains 50% DCD (AB grade), and 0.15% xanthan gum in a 20-0-0 (i.e. 20% nitrogen) urea solution slurry. The above basic process was carried out as follows: 937.98 grams of 20-0-0 urea solution was added to the mixing vessel and mixed while 2.84 grams of xanthan gum was added over the course of 1 minute. After 5 minutes of mixing, the xanthan gum+urea mixture was tested for viscosity on a DV-II+Brookfield viscometer with a #18 spindle at 20 rpm. The viscosity reading was 112.5 cP. The above step was repeated 4 additional times (total of 5), until the last three viscosity measurements read 247.8 cP, 257.4 cP, and 247 cP. It was then determined that 25 minutes was the point of saturation for the xanthan gum. 946.5 grams of the DCD were added along with 5.68 grams of dye to the mixture. After the dye addition, the mixture was mixed for 10 minutes.

Example 3Method of Making Aqueous Suspension Composition #3

[0034] Aqueous Suspension Composition #3 contains 43.7% DCD (AB grade), 3.30% NBPT, and 0.21% xanthan gum in a 32-0-0 (32% nitrogen) UAN slurry. The above basic process was carried out as follows: 993.25 grams of 32-0-0 UAN was added to the mixing vessel and mixed while 3.98 grams of xanthan gum was added over the course of 1 minute. After 5 minutes of mixing, the xanthan gum+urea mixture was tested for viscosity on a DV-II+Brookfield viscometer with a #31 spindle at 100 rpm. The viscosity was 254 cP. The above step was repeated 5 additional times (total of 6), until the last three viscosity measurements read 53500 cP, 57600 cP, and 57600 cP. It was then determined that 30 minutes was the point of saturation for the xanthan gum. 827.4 grams of DCD and 62.47 grams of NBPT were added along with 6.05 grams of dye to the mixture. After the dye addition, the mixture was mixed for 10 minutes.

Example 4Method of Making Aqueous Suspension Composition #4

[0035] Aqueous Suspension Composition #4 contains 43.7% DCD (AB grade), 3.30% NBPT, and 0.25% xanthan gum in a 32-0-0 (32% nitrogen) UAN slurry. The same procedure as Example 3 was followed, except that 0.25% xanthan gum was used. The final 3 viscosity measurements were 26410 cP, 25800 cP, and 27400 cP. It was t determined that 30 minutes was the point of saturation for the xanthan gum.

Example 5Method of Making Aqueous Suspension Composition #5

[0036] Aqueous Suspension Composition #5 contains 46.3% DCD (AB grade), 3.35% NBPT, and 0.18% xanthan gum in a 32-0-0 UAN slurry. The above basic process was carried out as follows: 944.04 grams of 32-0-0 UAN was added to the mixing vessel and mixed while 3.41 grams of xanthan gum was added over the course of 1 minute. After 5 minutes of mixing, the xanthan gum+urea mixture was tested for viscosity on a DV-II+Brookfield viscometer with a #18 spindle at 100 rpm. The viscosity was 890 cP. The above step was repeated 4 additional times (total of 5), until the last three viscosity measurements read 1560 cP, 1960 cP, and 1955 cP. It was then determined that 30 minutes was the point of saturation for the xanthan gum. 876.46 grams of DCD and 63.42 grams of NBPT were added along with 5.68 grams of dye to the mixture. After the dye addition, the mixture was mixed for 10 minutes.

Example 6Method of Making Aqueous Suspension Composition #6

[0037] Aqueous Suspension Composition #6 contains 46.89% DCD (AB grade), 3.90% NBPT, and 0.15% xanthan gum in a 32-0-0 UAN slurry with 0.10% Proxel GXL biocide. The above basic process was carried out as follows: 887.63 grams of 32-0-0 UAN was added to the mixing vessel and mixed while 2.84 grams of xanthan gum was added over the course of 1 minute. After 20 minutes of mixing, the xanthan gum+urea mixture was tested for viscosity on a DV-II+Brookfield viscometer with a #31 spindle at 100 rpm. The viscosity was 153 cP. The above step was repeated 4 additional times (total of 5), until the last three viscosity measurements read 460 cP, 530 cP, and 500 cP. It was then determined that 40 minutes was the point of saturation for the xanthan gum. 921.13 grams of DCD and 73.83 grams of NBPT were added along with 5.68 grams of dye to the mixture. After the dye addition, the mixture was mixed for 10 minutes. 1.66 mL of biocide was added, then mixed for an additional 5 minutes.

Example 7Method of Making Aqueous Suspension Composition #7

[0038] Aqueous Suspension Composition #7 contains 46.3% DCD (AB grade), 3.35% NBPT, and 0.18% xanthan gum in a 20-0-0 urea slurry with 0.17% Proxel GXL biocide. The above basic process was carried out as follows: 884.41 grams of 20-0-0 urea was added to the mixing vessel and mixed while 4.73 grams of xanthan gum was added over the course of 1 minute. After 20 minutes of mixing, the xanthan gum+urea mixture was tested for viscosity on a DV-II+Brookfield viscometer with a #31 spindle at 6 rpm. The viscosity was 575 cP. The above step was repeated 2 additional times (total of 3), until the last two viscosity measurements read 1330 cP and 1280 cP. It was then determined that 30 minutes was the point of saturation for the xanthan gum. 921.13 grams of DCD and 73.83 grams of NBPT were added along with 5.68 grams of dye to the mixture. After the dye addition, the mixture was mixed for 10 minutes. 2.82 mL of Proxel GXL biocide was then added to the mixture, and mixed for an additional 5 minutes.

Example 8Method of Making Aqueous Suspension Composition #8

[0039] Aqueous Suspension Composition #8 contains 48.66% DCD (AB grade), 3.90% NBPT, and 0.18% xanthan gum in a 20-0-0 urea slurry with 0.12% Proxel GXL biocide. The above basic process was carried out as follows: 886.68 grams of 20-0-0 urea was added to the mixing vessel and mixed while 3.41 grams of xanthan gum was added over the course of 1 minute. After 15 minutes of mixing, the xanthan gum+urea mixture was tested for viscosity on a DV-II+Brookfield viscometer with a #31 spindle at 100 rpm. The viscosity was 297 cP. The above step was repeated one additional time, until the final viscosity reading was 300 cP at 50 rpm. It was then determined that 25 minutes was the point of saturation for the xanthan gum. 921.13 grams of DCD and 73.83 grams of NBPT were added along with 5.68 grams of dye to the mixture. After the dye addition, the mixture was mixed for 10 minutes. 1.99 mL of Proxel GXL biocide was then added to the mixture, and mixed for an additional 5 minutes.

Example 9Method of Making Aqueous Suspension Composition #9

[0040] Aqueous Suspension Composition #9 contains 46% DCD (AB grade), 3.35% NBPT, and 0.25% xanthan gum in a 20-0-0 urea slurry with 0.17% Proxel GXL biocide. The above basic process was carried out as follows: 945.17 grams of 20-0-0 urea was added to the mixing vessel and mixed while 4.73 grams of xanthan gum was added over the course of 1 minute. After 20 minutes of mixing, the xanthan gum+urea mixture was tested for viscosity on a DV-II+Brookfield viscometer with a #31 spindle at 100 rpm. The viscosity was 258 cP. The above step was repeated two additional time (total of 3), until the final viscosity reading was 258 cP. It was then determined that 30 minutes was the point of saturation for the xanthan gum. 870.78 grams of DCD and 63.42 grams of NBPT were added along with 5.68 grams of dye to the mixture. After the dye addition, the mixture was mixed for 10 minutes. 2.82 mL of Proxel GXL biocide was then added to the mixture, and mixed for an additional 5 minutes.

Example 10Method of Making Aqueous Suspension Composition #10

[0041] Aqueous Suspension Composition #10 contains 40.55% DCD (AB grade), 3.25% NBPT, and 0.21% xanthan gum in a 20-0-0 urea slurry with 0.14% Proxel GXL biocide. The above basic process was carried out as follows: 870.78 grams of 20-0-0 urea was added to the mixing vessel and mixed while 3.98 grams of xanthan gum was added over the course of 1 minute. After 20 minutes of mixing, the xanthan gum+urea mixture was tested for viscosity on a DV-II+Brookfield viscometer with a #31 spindle at 100 rpm. The viscosity was 255 cP. The above step was repeated three additional time (total of 4), until the final viscosity reading was 258 cP. It was then determined that 35 minutes was the point of saturation for the xanthan gum. 870.78 grams of DCD and 61.52 grams of NBPT were added along with 5.68 grams of dye to the mixture. After the dye addition, the mixture was mixed for 10 minutes. 2.32 mL of Proxel GXL biocide was then added to the mixture, and mixed for an additional 5 minutes.

Example 11Method of Making Aqueous Suspension Composition #11

[0042] Aqueous Suspension Composition #10 contains 48.66% DCD (AB grade), 3.90% NBPT, and 0.21% xanthan gum in a 20-0-0 urea slurry with 0.14% Proxel GXL biocide. The above basic process was carried out as follows: 885.73 grams of 20-0-0 urea was added to the mixing vessel and mixed while 3.98 grams of xanthan gum was added over the course of 1 minute. After 20 minutes of mixing, the xanthan gum+urea mixture was tested for viscosity on a DV-II+Brookfield viscometer with a #31 spindle at 6 rpm. The viscosity was 2610 cP. The above step was repeated three additional time (total of 4), until the final two viscosity readings were 5570 cP and 5560 cP measured at 3 rpm. It was then determined that 40 minutes was the point of saturation for the xanthan gum. 921.13 grams of DCD and 73.83 grams of NBPT were added along with 5.68 grams of dye to the mixture. After the dye addition, the mixture was mixed for 10 minutes. 2.32 mL of Proxel GXL biocide was then added to the mixture, and mixed for an additional 5 minutes.