Composition comprising polyurethane microcapsules comprising cinmethylin

Abstract

The present invention relates to a composition comprising microcapsules, wherein the micro-capsules comprise a polyurea shell and a core, wherein the core comprises cinmethylin and the shell comprises a polymerization product of a tetramethylxylylene and an aliphatic diamine diisocyanate, and, optionally, a cycloaliphatic diisocyanate; to a method for preparing the composition comprising the steps of contacting water, cinmethylin, the diisocyanate and the aliphatic diamine; and to a method of controlling undesired plant growth and/or for regulating the growth of plants, wherein the composition is allowed to act on the soil and/or on undesired plants and/or on the crop plants and/or on their environment.

Claims

1-13. (canceled)

14. A composition comprising microcapsules, wherein the microcapsules comprise a polyurea shell and a core, wherein the core comprises cinmethylin and the shell comprises a polymerization product of a tetramethylxylylene diisocyanate, and an aliphatic diamine.

15. A composition of claim 14, wherein the shell comprises a polymerization product of a tetramethylxylylene diisocyanate, a cycloaliphatic diisocyanate, and an aliphatic diamine.

16. The composition of claim 14, wherein the tetramethylxylylene diisocyanate is the compound of formula (II) ##STR00004##

17. The composition of claim 14, wherein the aliphatic diamine is of the formula H.sub.2N(CH.sub.2).sub.nNH.sub.2, wherein n is an integer from 2 to 8.

18. The composition of claim 14, wherein the aliphatic diamine is hexane-1,6-diamine.

19. The composition of claim 15, wherein the cycloaliphatic diisocyanate is the compound of formula (I) ##STR00005##

20. The composition of claim 15, wherein the weight ratio of the tetramethylxylylene diisocyanate to the cycloaliphatic diisocyanate is at least 5:2.

21. The composition of claim 15, wherein the polyurea shell comprises 50 to 80 wt % of the tetramethylxylylene diisocyanate, 1 to 20 wt % of the cycloaliphatic diisocyanate, 15 to 35 wt % of the aliphatic diamine and the weight ratio of the tetramethylxylylene diisocyanate to the cycloaliphatic diisocyanate is at least 5:2.

22. The composition of claim 14, wherein the polyurea shell comprises up to 10 wt % of further polyisocyanates, which have at least two isocyanate groups and which are different from the tetramethylxylylene diisocyanate and from the cycloaliphatic diisocyanate.

23. The composition of claim 14 wherein the polyurea shell comprises up to 10 wt % of further polyamines, which have at least two amine groups and which are different from the aliphatic diamine.

24. The composition of claim 14, wherein the weight ratio of the diisocyanate and, optionally, of the further polyisocyanates to the aliphatic diamine and, optionally, of the further polyamines, is in the range from 20:1 to 2:1.

25. A method for preparing the composition as defined in claim 14 comprising the steps of contacting water, cinmethylin, the tetramethylxylylene diisocyanate, the aliphatic diamine and, optionally, the cycloaliphatic diisocyanate.

26. A method of controlling undesired plant growth and/or for regulating the growth of plants, wherein the composition as defined in claim 14 is allowed to act on the soil and/or on undesired plants and/or on the crop plants and/or on their environment.

27. A method of claim 26, wherein the shell comprises a polymerization product of a tetramethylxylylene diisocyanate, a cycloaliphatic diisocyanate, and an aliphatic diamine.

28. The method of claim 26, wherein the tetramethylxylylene diisocyanate is the compound of formula (II) ##STR00006##

29. The method of claim 26, wherein the aliphatic diamine is of the formula H.sub.2N(CH.sub.2).sub.nNH.sub.2, wherein n is an integer from 2 to 8.

30. The method of claim 26, wherein the aliphatic diamine is hexane-1,6-diamine.

31. The method of claim 30, wherein the cycloaliphatic diisocyanate is the compound of formula (I) ##STR00007##

32. The method of claim 30, wherein the weight ratio of the tetramethylxylylene diisocyanate to the cycloaliphatic diisocyanate is at least 5:2.

33. The method of claim 30, wherein the polyurea shell comprises 50 to 80 wt % of the tetramethylxylylene diisocyanate, 1 to 20 wt % of the cycloaliphatic diisocyanate, 15 to 35 wt % of the aliphatic diamine and the weight ratio of the tetramethylxylylene diisocyanate to the cycloaliphatic diisocyanate is at least 5:2.

34. The method of claim 26, wherein the polyurea shell comprises up to 10 wt % of further polyisocyanates, which have at least two isocyanate groups and which are different from the tetramethylxylylene diisocyanate and from the cycloaliphatic diisocyanate.

35. The method of claim 26, wherein the polyurea shell comprises up to 10 wt % of further polyamines, which have at least two amine groups and which are different from the aliphatic diamine.

36. The method of claim 26, wherein the weight ratio of the diisocyanate and, optionally, of the further polyisocyanates to the aliphatic diamine and, optionally, of the further polyamines, is in the range from 20:1 to 2:1.

Description

EXAMPLES

[0086] The examples below give further illustration of the invention, which is not, however, restricted to these examples. [0087] TMXDI: tetramethyl-m-xylylene diisocyanate, CAS 2778-42-9 [0088] Cyclic diisocyanate: bis(4-isocyanotocyclohexyl) methane (compound of formula (I)) [0089] Lignosulfonate: sodium salt of lignosulfonate, based on Kraft lignin, molecular weight about 3000 g/mol, water-soluble, CAS 68512-34-5 [0090] Additive A: sodium salt of naphthalene sulfonate condensate [0091] Additive B: hydrophobically modified polyacrylate, anionic polymeric dispersant, powder, molecular weight 1-20 kDa, pH 7-8.5 (1 wt % in water) [0092] Additive C: Poly[(2-ethyldimethylammonioethyl methacrylate ethyl sulfate)-co-(1-vinylpyrrolidone)], commercially available as Polyquaternium D11 [0093] Additive D: Polyvinylalcohol, commercially available as Koraray Poval 25-88 KL [0094] Biocide: water based formulation of 2-methyl-4-isothiazolin-3-one and 1,2-benzisothiazolin-3-one

[0095] Experiments 1-6

Preparation of Cinmethylin Microcapsules

[0096] The oil phase comprising cinmethylin, TMXDI and the cyclic diisocyanate was added at 65 C. to the water phase, which comprised Lignosulfonate, and emulsified using high-shear equipment. After emulsification, the emulsification device was replaced by a low shear stirrer and the hexa-methylene diamine was added. Subsequently, the dispersion was smoothly agitated for 30-60 minutes at 60 C. Under stirring the aqueous finish solution comprising Additives A and B, 1,2-propylene glycol, xanthan gum, a silicon defoamer, and a biocide was added to the capsule dispersion and the pH adjusted to pH 6-8 by addition of acetic acid. All experiments resulted in discrete microcapsule suspensions with a capsule diameter of 1-30 m (D.sub.50).

TABLE-US-00001 TABLE 1 Experiment 1 Experiment 2 Experiment 3 Amount [g/L] Amount [g/L] Amount [g/L] Cinmethylin 480 480 480 TMXDI 15.5 15.1 14.2 Cyclic diisocyanate 1.2 1.7 2.6 Hexane-1,6-diamine 6.6 6.6 6.6 Lignosulfonate 12.0 12.0 12.0 Additive A 15.0 15.0 15.0 Additive B 15.0 15.0 15.0 1,2-Propylene glycol 15.0 50.0 15.0 Xanthan gum 0.45 0.45 0.45 Silicone defoamer 1.0 1.0 1.0 Biocide 2.0 2.0 2.0 Water Ad 1.0 L Ad 1.0 L Ad 1.0 L Experiment 4 Experiment 5 Experiment 6 Amount [g/L] Amount [g/L] Amount [g/L] Cinmethylin 480 400 400 TMXDI 11.2 14.9 15.1 Cyclic diisocyanate 5.6 0 1.7 Hexane-1,6-diamine 6.6 5.9 6.6 Lignosulfonate 12.0 12.0 12.0 Additive A 15.0 15.0 15.0 Additive B 15.0 15.0 15.0 1,2-Propylene glycol 50.0 50.0 50.0 Xanthan gum 0.45 0.45 0.45 Silicone defoamer 1.0 1.0 1.0 Biocide 2.0 2.0 2.0 Water Ad 1.0 L Ad 1.0 L Ad 1.0 L

Experiment 7

Measurement of Viscosity

[0097] The viscosity of the aqueous microcapsule dispersions obtained in Experiments 1-4 were determined by rotational viscometry (Table 2). The method allows for the characterization of the flow behavior of liquid crop protection formulations. A rotational viscometer may be used to characterize both Newtonian and non-Newtonian liquids with a 1% accuracy with a CV of <0.5%. A sample was transferred to a standard rheometer (TA AR 2000) consisting of a cone and a plate (angle 1, diameter 60 mm). After calibration, the measurement was carried out under different shear conditions and the apparent viscosities were determined. The apparent viscosity is determined in mPa.Math.s and is defined as the ratio of the shear stress ( in mPa) divided by the shear rate ( in s.sup.1).

=(mPa.Math.s)

[0098] During the test the temperature of the liquid was kept constant at 20 C. The shear rate was brought to 100 s.sup.1 in one minute. Then 10 measurements were made at 100 s.sup.1 over 10 seconds. The 10th measurement of the 10 second interval at a shear rate of 100 s.sup.1 was declared apparent viscosity.

TABLE-US-00002 TABLE 2 Weight ratio Viscosity at 100 s.sup.1 TMXDI:Cyclic diisocyanate [mPas] Experiment 1 13:1 183 Experiment 2 9:1 150 Experiment 3 5.5:1 92 Experiment 4 2:1 668

[0099] For agrochemical formulations a viscosity in the range from 80 to 400 mPas at 100 s.sup.1 is acceptable. The results demonstrate that the composition of Experiment 4 has a viscosity, which is clearly outside this range.

Experiments 8-10

Comparative Examples

[0100] In accordance with the preparative instructions given in WO 94/13139 A1 two microcapsule suspension compositions (experiments 8 and 9 in table 3) were prepared, which represent capsules obtained in example 6 of WO 94/13139 A1. Since the emulsifier Agrimer DA-10 was no longer commercially available at the time the experiments were conducted, it was replaced by Additive C, a copolymer which is chemically and physically very similar.

[0101] Experiment 10 reproduced microcapsules following the procedure described in WO 2015/165834 A1, example 8.

[0102] Experiments 8-10 resulted in discrete microcapsule suspension with a diameter of 1-30 m (D.sub.50) as described in the prior art.

TABLE-US-00003 TABLE 3 Experiment 8* Experiment 9* Experiment 10** Amount [g/L] Amount [g/L] Amount [g/L] Cinmethylin 535 535 427.68 Methylenediphenyldiisocyanate 37.23 37.23 Hexamethylene diisocyanate, 15.34 Bayhydur XP 2547 Dicyclohexylmethane diisocyanat, 54.54 Desmodur Additive C 10.71 5.36 Additive D 34.99 Polyethyleneimine 27.97 Hexane-1,6-diamine 16.12 16.12 Water Ad 1.0 L Ad 1.0 L Ad 1.0 L *Comparative example according to WO 94/13139 A1 **Comparative example according to WO 2015/165834 A1

[0103] Herbicidal Efficacy

[0104] The effects on the growth of undesirable plants of the herbicidal compositions comprising microcapsules, which were obtained in experiments 5, 6, 8, 9 and 10, was demonstrated by the following greenhouse experiments:

[0105] The test plants were seeded in plastic containers in sandy loamy soil containing 5% of organic matter. For the pre-emergence treatment, the compositions were applied directly after sowing by means of finely distributing nozzles at a use rate of 500 g active ingredient/ha. The containers were irrigated gently to promote germination and growth and subsequently covered with transparent plastic hoods until the plants had rooted. This cover caused uniform germination of the test plants unless this was adversely affected by the active compounds. The plants were cultivated according to their individual requirements at 10-25 C. and 20-35 C.

[0106] In the following experiments, the herbicidal activity for the individual herbicidal compositions was assessed 20 days after treatment. The results are summarized in table 4. The evaluation for the damage on undesired weeds caused by the compositions was carried out using a scale from 0 to 100%, compared to the untreated control plants. Here, 0 means no damage and 100 means complete destruction of the plants.

[0107] The plants used in the greenhouse experiments belonged to the following species:

TABLE-US-00004 EPPO Code Scientific name ALOMY Alopecurus myosuroides LOLRI Lolium rigidum BROST Bromus sterilis MATIN Tripleurospermum inodorum PAPRH Papaver thoeas GALAP Galium aparine

TABLE-US-00005 TABLE 4 Formulation ALOMY LOLRI BROST MATIN PAPRH GALAP EC 100 100 98 85 90 85 formulation of Cinmethylin Experiment 5 100 100 100 65 95 60 Experiment 6 98 80 85 65 95 10 Experiment 30 0 0 50 0 45 8* Experiment 15 15 0 40 0 40 9* Experiment 30 0 0 50 0 45 10** *Comparative example according to WO 94/13139 A1 **Comparative example according to WO 2015/165834 A1

[0108] The herbicidal activity of the microcapsule suspensions of the prior art was low compared to the capsules according to the present invention. The results demonstrate, that the capsules according to the present invention have a similar weed activity as a typical EC type formulation and a better efficacy than microcapsule compositions of the prior art.

[0109] Release Test

[0110] The amount of released active ingredient over time was determined as followed:

[0111] First a 10% solution of Poloxamer 335 (Pluronic PE 10500, EO/PO block-copolymer) was prepared, which was adjusted to pH 5 with acetic acid. This solution acted as receiver solution for the non-encapsulated active or the released active. To 250 mL of the receiver solution 125 mg of the microcapsule suspension was added. The solution was stirred and at defined time points, a sample was drawn. A 0.2 m Teflon filter was used to remove the remaining microcapsules.

[0112] In the filtrate, the pesticide was determined via reverse phase HPLC and normalized in a way that the entire amount of the Pesticide would account for 100%. This would have been found for example if no encapsulation would have taken place (like in an EC formulation) or all of the pesticide would have been released. The release rates are summarized in table 5. The results demonstrate that the microcapsule compositions according to the present invention controlled the release rate of cinmethylin so that a rapid loss of the active ingredient due to its volatility was prevented.

TABLE-US-00006 TABLE 5 10 min 5 h 24 h 3 d 7 d Experiment 5 50 56 56 57 57 Experiment 6 53 55 55 55 55 Experiment 8* 0 0 1 6 19 Experiment 9* 0 2 9 20 48 Experiment 10** 0 0 1 2 4 *Comparative example according to WO 94/13139 A1 **Comparative example according to WO 2015/165834 A1