STORAGE-STABLE SOLUTIONS CONTAINING CYANAMIDE

Abstract

The invention relates to aqueous solutions containing cyanamide, particularly storage-stable aqueous solutions containing cyanamide which contain a stabilizer and a surfactant.

Claims

1-10. (canceled)

11. A solution containing cyanamide, comprising a) 15 to 60% by weight of cyanamide, b) 0.01 to 4% by weight of a stabilizer comprising one or more compounds from the group of phosphorus-containing acids or the salts thereof, c) 0.01 to 4% by weight of a nonionic surfactant containing one or more compounds selected from the group of ethoxylates according to formula (I), fatty alcohol glucosides according to formula (II) or mixtures thereof, wherein for formula (I) and (II) the following applies, ##STR00006## wherein for the radicals R.sup.1, R.sup.2 and the indices n, m, the following applies, together or independently: R.sup.1=a linear or branched alkyl or alkenyl group having 6 to 24 carbon atoms, a partially or fully fluorinated alkyl group having 6 to 18 carbon atoms, a phenyl group, an alkyl-substituted phenyl group, a mono- or polyfunctional siloxane group, R.sup.2=a linear or branched alkyl or alkenyl group having 6 to 24 carbon atoms, n=a number from 2 to 20, m=a number from 1 to 5, d) balance water, wherein the components a) and c) are present in a weight ratio of cyanamide to nonionic surfactant in the range from 500:1 to 5:1.

12. The solution containing cyanamide according to claim 11, wherein the solution containing cyanamide comprises 30 to 60% by weight cyanamide.

13. The solution containing cyanamide according to claim 12, wherein the solution containing cyanamide comprises 35 to 52% by weight cyanamide.

14. The solution containing cyanamide according to claim 11, wherein the solution containing cyanamide comprises, as the nonionic surfactant, a compound selected from the group of ethoxylates of formula (I), wherein for the radical R.sup.1 and the indices u, v, y and n the following applies: R.sup.1=a linear or branched alkyl group with 8 to 18 carbon atoms, alkyl-substituted phenyl group, a polyfunctional siloxane group according to formula (V), wherein for formula (V) the following applies ##STR00007## wherein for the indices u, v and y, independently from each other, the following applies: u=a number from 0 to 3 and v=a number from 0 to 3, y=a number from 2 to 10, n=a number from 2 to 10.

15. The solution containing cyanamide according to claim 11, wherein the solution containing cyanamide comprises, as the nonionic surfactant, a compound selected from the group of fatty alcohol glucosides according to formula (II), wherein for the radical R.sup.2 and the index m the following applies: R.sup.2=a linear alkyl group having 8 to 18 carbon atoms, m=a number from 2 to 5.

16. The solution containing cyanamide according to claim 11, wherein the solution containing cyanamide comprises, as a stabilizer, one or more compounds from the group of phosphorus-containing acids or the salts thereof.

17. The solution containing cyanamide according to claim 16, wherein the one or more compounds from the group of phosphorus-containing acids or the salts thereof is selected from the group consisting of orthophosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, and magnesium hydrogen phosphate.

18. The solution containing cyanamide according to claim 11, wherein the solution has a pH in the range from 3.5 to 5.5.

19. The solution containing cyanamide according to claim 18, wherein the solution has a pH in the range from 3.9 to 4.5.

20. The solution containing cyanamide according to claim 11, wherein the solution containing cyanamide further comprises up to 6% by weight of dicyandiamide.

21. The solution containing cyanamide according to claim 20, wherein the solution containing cyanamide further comprises from 0 to 2% by weight of dicyandiamide.

22. The solution containing cyanamide according to claim 11, wherein the solution has a viscosity of less than 1 Pa*s (25 C.).

23. The solution containing cyanamide according to claim 11, wherein the solution containing cyanamide further comprises up to 5% by weight of formulation adjuvants,

24. The solution containing cyanamide according to claim 23, wherein the solution containing cyanamide further comprises 0 to 2% by weight of formulation adjuvants.

25. Use of a solution containing cyanamide according to claim 11 as a means for promoting or regulating plant growth

26. Use of a solution containing cyanamide according to claim 11, as a fertilizer or as a plant growth regulator.

Description

EXAMPLES

I) Raw Materials Used

[0093] a) industrial, ground calcium cyanamide (manufacturer: AlzChem AG) with 23.1% total nitrogen content, 22.2% cyanamide nitrogen and 0.1% calcium carbide content. [0094] b) commercial 85% phosphoric acid [0095] c) magnesium hydrogen phosphate-trihydrate of the formula MgHPO.sub.4.3H.sub.2O, manufacturer: Aldrich. Order no. M1265 [0096] d) ethoxylated iso-tridecanol having an average of 5 ethylene oxide units, trade name: Marlipal 013/50 produced by Evonik [0097] e) ethoxylated trisiloxane, trade name: Break-Thru S240 produced by Evonik [0098] f) octadecyl polyglucoside having an average of 3 glucose units, trade name: Cognis APG from Cognis [0099] g) nonyl phenyl ethoxylate with an average of 5 ethylene oxide units, trade name: Triton N-57 from Dow Chemical [0100] H) sodium stearate from TCI Europe, order no. S00081 [0101] i) sodium dodecyl sulphate from Aldrich, no. 436143

II) Methods of Analysis

[0102] a) The cyanamide content was determined by potentiometric titration with silver nitrate against a silver electrode. The solvent was prepared as follows: 10 ml of a 1 molar sodium hydroxide solution and 20 ml of a 2 molar ammonia solution were mixed with 330 ml of ethanol and filled up with water to 1000 ml. A weight corresponding to about 5 mg cyanamide was placed in 50 ml of this solvent and titrated with a 0.05 molar silver nitrate solution, wherein yellow silver cyanamide Ag.sub.2NCN precipitated. The titration endpoint for the evaluation corresponded to the inflection point of the potential at the silver electrode. [0103] b) Dicyandiamide (DCD) was determined by reverse phase HPLC against an external standard of known content. Column used: Nucleosil 5 C-18 at 20 C. Mobile phase: 1% methanol in water. Detection wavelength: 220 nm. [0104] c) The pH was measured by means of a calibrated glass electrode (AgCl/Ag reference electrode) without further sample preparation. [0105] d) Phosphate was isolated by means of ion chromatography against an external standard with known phosphate content. Column used: Dionex HPIC AS3 at 20 C. Buffered high purity water with an addition of 233 ppm sodium carbonate and 235 ppm sodium bicarbonate were used as a mobile phase. Detection by means of conductivity sensor.

III) Test Method for Storage of the Investigated Cyanamide Solutions

[0106] 250 ml soda glass narrow mouth bottles were washed with deionized purified water to remove adhering traces of alkali. 200 g of the solution to be examined were each filled into a bottle prepared in this way. The bottles to be tested were each stored in a calibrated convection drying cabinet at an internal temperature of 30 or 60 C. For each test temperature and each test period, a separate bottle was used. After the end of the test period, the respective bottle was removed from the drying cabinet, cooled to 20 C. and examined with regard to cyanamide, DCD and pH according to the above analysis methods.

[0107] The examined test periods were: [0108] at 60 C. (accelerated storage test): 24 hours, 48 hours and 96 hours, respectively [0109] at 30 C. (normal storage test): 90 or 180 days

IV) Preparation of the Aqueous Cyanamide-Containing Compositions (Solutions)

[0110] Solution 1a)

[0111] 720 kg of industrial, ground calcium cyanamide were reacted with 800 kg of process water at 20 C. under a pressure of 3 bar with technically pure carbon dioxide gas. The precipitated calcium carbonate was filtered off together with the insoluble by-products contained in the lime nitrogen (including graphite). The filtrate was adjusted from pH 6.9 to pH 4.0 with 2.3 kg of 85% phosphoric acid. The resulting 33% cyanamide solution (about 1000 kg) was partially evaporated under reduced pressure (about 20 mbar) at 30-40 C. About 650 kg of the sample solution 1a were obtained as distillation residue. This sample solution 1a had the following composition:

cyanamide content: 50.7%, dicyandiamide content: 0.8%, pH 4.3, phosphate content: 0.3%.

[0112] Solution 1 b)

[0113] 720 kg of industrial calcium cyanamide were reacted with 800 kg of process water at 20 C. under a pressure of 3 bar with technically pure carbon dioxide gas. The precipitated calcium carbonate was filtered off together with insoluble by-products (including graphite) contained in calcium cyanamide. The filtrate was mixed with 1.4 kg of magnesium hydrogen phosphate trihydrate and adjusted from pH 5.6 to pH 4.3 with 1.3 kg of 85% phosphoric acid. The obtained cyanamide solution of about 33% was partially evaporated at 30-40 C. under reduced pressure (about 20 mbar). Approximately 630 kg of the sample solution 1b were obtained as distillation residue. These sample solution 1b had the following composition:

cyanamide content: 51.1%, dicyandiamide content 0.8%, pH 4.5, phosphate content 0.3%, magnesium content; 0.03%.

[0114] Solution 1c)

[0115] 720 kg of industrial calcium cyanamide were reacted with 800 kg of process water at 20 C. under a pressure of 3 bar with technically pure carbon dioxide gas. The precipitated calcium carbonate was filtered off together with the insoluble by-products contained in the lime nitrogen (including graphite). The filtrate was mixed with 1.4 kg of magnesium hydrogen phosphate trihydrate and brought from pH 5.6 to pH 4.3. by means of 3 kg of 85% strength phosphoric acid. The obtained about 33% cyanamide solution was partially evaporated at 30-40 C. under reduced pressure (about 20 mbar). About 800 kg of the sample solution 1c were obtained as a distillation residue. This sample solution 1c had the following composition:

cyanamide content: 40.2%, dicyandiamide content 0.6%, pH 4.3, phosphate content 0.2%, magnesium content; 0.02%.

[0116] Surfactant-Containing Solutions 2a to 7b

[0117] The surfactant-containing solutions 2a to 7b were prepared by adding 990 g of the starting solutions 1a or 1b or 1c by adding 10 g of each specified surfactant and the mixture was stirred to homogeneity. The cyanamide concentration of the starting solutions is thereby slightly reduced, which has been confirmed by appropriate analyses. The pH did not change in a measurable way when using the nonionic surfactants according to the invention. When using anionic surfactants, the pH changed in some cases significantly.

TABLE-US-00001 TABLE 1a aqueous cyanamide-containing composition (according to the invention) Content of No. cyanamide Stabilizer Nonionic surfactant 1a (comparison) 50.7% by 0.3% by weight of none weight phosphate 1b (comparison) 50.1% by 0.3% by weight of none weight phosphate 0.03% by weight Mg.sup.2+ 1c (comparison) 40.2% by 0.2% by weight of none weight phosphate 0.02% by weight Mg.sup.2+ 2a (according to 50.2% by 0.3% by weight of 1% by weight of the invention) weight phosphate ethoxy iso- tridecanol according to I) d) 2b (according to 50.6% by 0.3% by weight of 1% by weight of the invention) weight phosphate ethoxy iso- 0.03% by weight tridecanol according Mg.sup.2+ to I) d) 2c (according to 39.8% by 0.2% by weight of 1% by weight of the invention) weight phosphate ethoxy iso- 0.02% by weight tridecanol according Mg.sup.2+ to I) d) 3a (according to 50.2% by 0.3% by weight of 1% by weight of the invention) weight phosphate ethoxy trisiloxane according to I) e) 3b (according to 50.6% by 0.3% by weight of 1% by weight of the invention) weight phosphate ethoxy trisiloxane 0.03% by weight according to I) e) Mg.sup.2+ 3c (according to 39.8% by 0.2% by weight of 1% by weight of the invention) weight phosphate ethoxy trisiloxane 0.02% by weight according to I) e) Mg.sup.2+ 4a (according to 50.2% by 0.3% by weight of 1% by weight the invention) weight phosphate octadecyl- polyglucoside according to I) f) 4b (according to 50.6% by 0.3% by weight of 1% by weight the invention) weight phosphate octadecyl- 0.03% by weight polyglucoside Mg.sup.2+ according to I) f) 5a (according to 50.2% by 0.3% by weight of 1% by weight of the invention) weight phosphate ethoxy nonylphenol according to I) g) 5b (according to 50.6% by 0.3% by weight of 1% by weight of the invention) weight phosphate ethoxy nonylphenol 0.03% by weight according to I) g) Mg.sup.2+

TABLE-US-00002 TABLE 1b aqueous cyanamide-containing composition (not according to the invention) Content of No. cyanamide Stabilizer Nonionic surfactant 6a 50.2% by 0.3% by weight of 1% by weight of Na (not according to weight phosphate stearate according the invention) to I)h) 6b 50.6% by 0.3% by weight of 1% by weight of Na (not according to weight phosphate stearate according the invention) 0.03% by weight to I)h) Mg.sup.2+ 7a 50.2% by 0.3% by weight of 1% by weight of Na (not according to weight phosphate dodecylsulfate the invention) according to I)i) 7b 50.6% by 0.3% by weight of 1% by weight of Na (not according to weight phosphate dodecylsulfate the invention) 0.03% by weight according to I)i) Mg.sup.2+

TABLE-US-00003 TABLE 2a Storage stability of the compositions according to Table 1a - at 60 C. After 24 After 48 After 96 No. Investigated values Initial value hours hours hours 1a pH value 4.3 5 5.6 Content of cyanamide 50.7 49.2 47.2 [% by weight] Content of DCD [% by 0.8 2.3 4.3 weight] 1b pH value 4.5 5.1 5.8 Content of cyanamide 51.1 49.6 46.0 [% by weight] Content of DCD [% by 0.8 2.1 5.8 weight] 1c pH value 4.3 5.0 5.6 Content of cyanamide 40.2 38.8 35.9 [% by weight] Content of DCD [% by 0.6 1.8 4.6 weight] 2a pH value 4.3 4.6 5.1 Content of cyanamide 50.2 49.5 47.5 [% by weight] Content of DCD [% by 0.8 1.7 3.1 weight] 2b pH value 4.5 4.8 5.3 Content of cyanamide 50.6 49.8 46.9 [% by weight] Content of DCD [% by 0.8 1.7 4.2 weight] 2c pH value 4.3 4.7 5.4 Content of cyanamide 39.8 39.3 36.6 [% by weight] Content of DCD [% by 0.6 1.5 3.9 weight] 3a pH value 4.3 4.7 5.2 Content of cyanamide 50.2 49.3 47.7 [% by weight] Content of DCD [% by 0.8 1.8 3.3 weight] 3b pH value 4.5 4.7 5.3 Content of cyanamide 50.6 49.7 47.1 [% by weight] Content of DCD [% by 0.8 1.7 4.4 weight] 3c pH value 0.6 4.8 5.3 Content of cyanamide 39.8 39.2 36.8 [% by weight] Content of DCD [% by 4.3 1.4 3.6 weight] 4a pH value 4.3 4.6 5.2 Content of cyanamide 50.2 49.4 47.9 [% by weight] Content of DCD [% by 0.8 1.6 3.0 weight] 4b pH value 4.5 4.9 5.4 Content of cyanamide 50.6 49.8 47.2 [% by weight] Content of DCD [% by 0.8 1.6 4.1 weight] 5a pH value 4.3 4.6 5.1 Content of cyanamide 50.2 49.3 47.8 [% by weight] Content of DCD [% by 0.8 1.7 3.2 weight] 5b pH value 4.5 4.8 5.3 Content of cyanamide 50.6 49.7 47.1 [% by weight] Content of DCD [% by 0.8 1.7 4.2 weight]

TABLE-US-00004 TABLE 3a Storage stability of the compositions according to Table 1a - at 30 C. After 180 No. Investigated values Initial value After 90 days days 1a pH value 4.3 5.8 6.2 Content of cyanamide 50.7 46.9 40.8 [% by weight] Content of DCD [% by 0.8 4.7 10.8 weight] 1b pH value 4.5 5.0 5.8 Content of cyanamide 51.1 48.6 45.0 [% by weight] Content of DCD [% by 0.8 3.3 6.8 weight] 1c pH value 4.3 4.9 5.6 Content of cyanamide 40.2 37.0 35.2 [% by weight] Content of DCD [% by 0.6 2.8 5.5 weight] 2a pH value 4.3 4.8 5.9 Content of cyanamide 50.2 47.6 43.4 [% by weight] Content of DCD [% by 0.8 3.5 7.8 weight] 2b pH value 4.5 4.7 5.3 Content of cyanamide 50.6 48.9 46.1 [% by weight] Content of DCD [% by 0.8 2.6 4.9 weight] 2c pH value 4.3 4.7 5.4 Content of cyanamide 39.8 37.9 36.4 [% by weight] Content of DCD [% by 0.6 2.1 4.5 weight] 3a pH value 4.3 4.8 5.9 Content of cyanamide 50.2 47.5 43.5 [% by weight] Content of DCD [% by 0.8 3.4 7.7 weight] 3b pH value 4.5 4.8 5.3 Content of cyanamide 50.6 48.0 46.5 [% by weight] Content of DCD [% by 0.8 2.4 5 weight] 3c pH value 4.3 4.7 5.3 Content of cyanamide 39.8 38.0 36.8 [% by weight] Content of DCD [% by 0.6 2.0 4.3 weight] 4a pH value 4.3 4.7 5.7 Content of cyanamide 50.2 47.3 43.3 [% by weight] Content of DCD [% by 0.8 3.3 7.5 weight] 4b pH value 4.5 4.7 5.3 Content of cyanamide 50.6 49.1 46.5 [% by weight] Content of DCD [% by 0.8 2.4 5.2 weight] 5a pH value 4.3 4.7 5.5 Content of cyanamide 50.2 47.5 43.5 [% by weight] Content of DCD [% by 0.8 3.5 7.4 weight] 5b pH value 4.5 4.8 5.3 Content of cyanamide 50.6 49.0 46.2 [% by weight] Content of DCD [% by 0.8 2.6 5.1 weight]

TABLE-US-00005 TABLE 2b Storage stability of the compositions according to Table 1b - at 60 C. Initial After 24 After 48 After 96 No. Investigated values value hours hours hours 1a pH value 4.3 5 5.6 (Comparison) Content of 50.7 49.2 47.2 cyanamide [% by weight] Content of DCD [% 0.8 2.3 4.3 by weight] 1b pH value 4.5 5.1 5.8 (Comparison) Content of 51.1 49.6 46 cyanamide [% by weight] Content of DCD [% 0.8 2.1 5.8 by weight] 6a pH value 5.7 5.9 6.4 Content of 50.2 48 44.9 cyanamide [% by weight] Content of DCD [% 0.8 3.2 6.1 by weight] 6b pH value 5.6 6.1 6.4 Content of 50.6 48.5 42.9 cyanamide [% by weight] Content of DCD [% 0.8 3 >10* by weight] 7a pH value 4.5 5.3 6.2 Content of 50.2 48.1 45.3 cyanamide [% by weight] Content of DCD [% 0.8 3 5.9 by weight] 7b pH value 4.6 5.2 6.2 Content of 50.6 48.9 43.5 cyanamide [% by weight] Content of DCD [% 0.8 2.7 7.9 by weight] *DCD precipitated as a solid

TABLE-US-00006 TABLE 3b Storage stability of the compositions according to Table 1b - at 30 C. Initial After 90 After 180 No. Investigated values value days days 1a pH value 4.3 5.8 6.2 (Com- Content of cyanamide [% by 50.7 46.9 40.8 parison) weight] Content of DCD [% by weight] 0.8 4.7 10.8 1b pH value 4.5 5.0 5.8 (Com- Content of cyanamide [% by 51.1 48.6 45.0 parison) weight] Content of DCD [% by weight] 0.8 3.3 6.8 6a pH value 5.7 6 6.4 Content of cyanamide [% by 50.2 44.4 35.2 weight] Content of DCD [% by weight] 0.8 6.8 >10* 6b pH value 5.6 6 6.3 Content of cyanamide [% by 50.6 46.7 41.2 weight] Content of DCD [% by weight] 0.8 4.7 >10* 7a pH value 4.5 5.9 6.3 Content of cyanamide [% by 50.2 44.7 35.9 weight] Content of DCD [% by weight] 0.8 6.4 >10* 7b pH value 4.6 5.4 6.1 Content of cyanamide [% by 50.6 47 41.7 weight] Content of DCD [% by weight] 0.8 4.5 9.6 *DCD precipitated as a solid

Evaluation of the Results

[0118] The solution (1a) shows a basic stabilization already sufficient for some applications, which can be improved by adding magnesium phosphate (solution (1b) or (1c)) (corresponding to the prior art). For many applications, however, even this improved stability is not sufficient.

[0119] By comparing the stability data of solutions (2a) to (5a) with solution (1a), or (2b) to (5b) with (1b) or (2c) and (3c) with (1c) at 30 (Table 3) or at 60 C. (Table 2) the additional stabilizing effect of nonionic surfactants is evident. The comparison with the stability data of solution (6a) and (7a) or (6b) and (7b) shows that, in contrast, anionic surfactants have a destabilizing effect, and that's why they are not part of the present invention.