POLYETHER-MODIFIED SILOXANES AS DUST BINDING AGENTS FOR SEED

Abstract

Polyether-modified siloxanes can be used as a dust binder for seed. Methods of reducing the evolution of dust from seed can be used with the polyether-modified siloxanes, and a treated seed is obtainable by these methods. Seed-dressing compositions or seed-dressing liquors contain the polyether-modified siloxanes.

Claims

1. A dust binder for seed, comprising at least one polyether-modified siloxane.

2. The dust binder for seed according to claim 1, wherein the at least one polyether-modified siloxane has 41 to 81 silicon atoms.

3. The dust binder for seed according to claim 1, wherein the at least one polyether-modified siloxane is a compound of the general formula (I) ##STR00004## wherein: R is in each case independently selected from the group consisting of monovalent hydrocarbyl radicals having 1 to 18 carbon atoms; R.sup.1 is in each case independently selected from the group consisting of R and R.sup.2; R.sup.2 is in each case independently selected from the group consisting of monovalent polyether radicals of the general formula (II)
—Z[(OC.sub.2H.sub.3R.sup.3).sub.cOR.sup.4].sub.d   Formula (II); wherein Z is in each case independently selected from the group consisting of (d+1)-valent hydrocarbyl radicals that are optionally interrupted by oxygen atoms and have 2 to 10, preferably 3 to and especially 3 carbon atoms; R.sup.3 is in each case independently selected from the group consisting of H and monovalent hydrocarbyl radicals having 1 to 8 carbon atoms; R.sup.4 is in each case independently selected from the group consisting of H, monovalent hydrocarbyl radicals having 1 to 8 carbon atoms, and acyl radicals having 1 to 8 carbon atoms; and wherein a=31 to 74; b=6 to 50; c=3 to 100; and d=1 to 3.

4. The dust binder for seed according to claim 3, wherein R=methyl, Z=—CH.sub.2CH.sub.2CH.sub.2—, R.sup.4=H, and d=1.

5. The dust binder for seed according to claim 3, wherein the divalent polyether radicals (OC.sub.2H.sub.3R.sup.3).sub.c are each independently selected from the group consisting of radicals of the general formula (III)
(OC.sub.2H.sub.4).sub.c(1)(OC.sub.3H.sub.6).sub.c(2)(OC.sub.4H.sub.8).sub.c(3)(OC.sub.2H.sub.3Ph).sub.c(4)   Formula (III) wherein Ph is phenyl; and wherein c(1)=1 to 100; c(2)=0 to 70; c(3)=0 to 5; c(4)=0 to 5; with the proviso that: c(1)+c(2)+c(3)+c(4)=c.

6. The dust binder for seed according to claim 5, wherein c(3)=c(4)=0.

7. The dust binder for seed according to claim 5, wherein c(1)/(c(2)+c(3)+c(4))=0.5 to 20.

8. The dust binder for seed according to claim 3, wherein a proportion by mass of oxyethylene groups (OC.sub.2H.sub.4) based on a total mass of all (OC.sub.2H.sub.3R.sup.3) groups is from 35% to 95%.

9. The dust binder for seed according to claim 3, wherein a number-average molecular weight of R.sup.2 is from 200 g/mol to 2500 g/mol.

10. The dust binder for seed according to claim 1, wherein the at least one polyether-modified siloxane has a cloud point of at least 30° C.

11. The dust binder for seed according to claim 1, wherein a proportion by mass of the at least one polyether-modified siloxane based on a total mass of a treated seed is from 0.001 ppm to 1000 ppm.

12. The dust binder for seed according to claim 1, wherein the seed is selected from the group consisting of grains from the grass family.

13. A method of reducing the evolution of dust from seed using the dust binder for seed according to claim 1, the method comprising: a. providing the seed, and b. treating the seed with the at least one polyether-modified siloxane.

14. A seed-dressing composition or seed-dressing liquor, comprising the dust binder for seed according to claim 1.

15. A treated seed, comprising a seed and the dust binder for seed according to claim 1.

16. The dust binder for seed according to claim 2, wherein the at least one polyether-modified siloxane has 45 to 70 silicon atoms.

17. The dust binder for seed according to claim 3, wherein in the formula (I), R is methyl and R.sup.1 is methyl.

18. The dust binder for seed according to claim 3, wherein in the formula (II), Z is in each case independently selected from the group consisting of (d+1)-valent hydrocarbyl radicals that are optionally interrupted by oxygen atoms and have 3 carbon atoms; R.sup.3 is in each case independently selected from the group consisting of H and methyl; and R.sup.4 is H.

19. The dust hinder for seed according to claim 11, wherein the proportion by mass of the at least one polyether-modified siloxane based on the total mass of the treated seed is from 0.1 ppm to 10 ppm.

20. The dust hinder for seed according to claim 12, wherein the seed is selected from the group consisting of a grain of wheat, rye, barley, oat, triticale, rice, maize, and millet/sorghum.

Description

EXAMPLES

General Methods

Determination of Dust Value

[0078] The determination of the dust values is conducted by the ESA 11.0387 (ESA STAT Dust Working Group, Version 1.0 of 23.03.2011) method. This involves conducting the Heubach test “Assessment of free floating dust and abrasion particles of treated seeds as a parameter of the quality of treated seeds” with a dustmeter from Heubach, type 1, according to the instructions. The Heubach test is the standard test conducted in industry for determining the dusting tendency of dressed seed. In the Heubach test, the adhesion or abrasion of the seed-dressing composition on the seed is measured. This is done by introducing 100 g of dressed seed into a drum that subsequently rotates. This subjects the seed to mechanical stress; an air stream is guided through the system. The seed dusts detached are sucked onto a filter unit, and the filter is weighed. The result is the Heubach value, which is often reported in g of dust per dt of dressed seed, but also g of dust per 100 000 seed grains. A calculated value of g of dust per ha is often also found.

Characterization of the Siloxanes

[0079] The siloxanes can be characterized with the aid of .sup.1H NMR and .sup.29Si NMR spectroscopy. These methods, especially taking account of the multiplicity of the couplings, are familiar to the person skilled in the art.

Determination of the SiH Values

[0080] The SiH values of the SiH-functional siloxanes used, and also those of the reaction matrices, are determined in each case using a gas-volumetric method by the sodium butoxide-induced decomposition of weighed aliquots of samples, using a gas burette. When the hydrogen volumes measured are inserted into the general gas equation, they allow determination of content of active SiH functions in the starting materials, and also in the reaction mixtures, and thus allow monitoring of conversion. A solution of sodium butoxide in butanol is used (5% by weight of sodium butoxide).

Synthesis of Polyether-Modified Siloxanes

Example 1

[0081] 17.8 g of polymethylhydrosiloxane (CAS: 63148-57-2, Gelest Inc., Code HMS-992 M.sub.eq.=63.8 g/mol SiH, i.e. 63.8 g based on the number of SiH groups) were mixed with 3.5 g of hexamethyldisiloxane and 78.7 g of octamethylcyclotetrasiloxane, and 0:1 g of trifluoromethanesulfonic acid (purity: 99% by weight) was added. The mixture was stirred at room temperature for 24 h. Subsequently, 2 g of NaHCO.sub.3 were added and the mixture was stirred for 4 h. The mixture was filtered, A dear liquid was obtained. The siloxane obtained was characterized with the aid of .sup.29Si NMR spectroscopy. An SiH-functional siloxane of the empirical formula Me.sub.3SiO[SiMe.sub.2O].sub.38[SiMeHO].sub.10SiMe.sub.3 was obtained. To prepare the polyether-modified polyethersiloxane, the SiH-functional siloxane was reacted with an unsaturated polyether in a hydrosilylation reaction. The hydrosilylation reaction was conducted in the presence of a complete platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution in xylene (purchased from Sigma-Aldrich, Pt content: 2% by weight) as Karstedt catalyst. The hydrosilylation reaction was brought to full conversion in relation to the hydrogen content of the SiH-functional siloxanes. In the context of the present disclosure, a full conversion is understood to mean that more than 99% of the SiH functions were converted. Detection is effected in the manner familiar to the person skilled in the art by gas-volumetric means after alkaline breakdown. Specifically, 262 g of an unsaturated polyether of the empirical formula CH.sub.2═CHCH.sub.2O[C.sub.2H.sub.5O].sub.13.9[CH.sub.2CH(CH.sub.3)O].sub.5.3H were mixed with 70 g of the SiH-functional siloxane of the empirical formula Me.sub.3SiO[SiMe.sub.2O].sub.38[SiMeHO].sub.10SiMe.sub.3 obtained beforehand in a 500 ml three-neck flask with precision glass stirrer and reflux condenser under a nitrogen blanket. The mixture was heated to 90° C. Subsequently, 0.16 g of a solution of the Karstedt catalyst in xylene (Pt content 2% by weight) was added to the mixture. An exothermic reaction set in. This was followed by stirring at 90° C. for 2 h. A clear liquid was obtained. The conversion of SiH functions was 100%. The reaction product obtained was a polyether-modified siloxane of the empirical formula Me.sub.3SiO[SiMe.sub.2O].sub.38[SiMeR.sup.2O].sub.10SiMe.sub.3 with R.sup.2=—CH.sub.2CH.sub.2CH.sub.2O[C.sub.2H.sub.5O].sub.13.9[CH.sub.2CH(CH.sub.3)O].sub.5.3H.

Example 2

[0082] Analogously to the mode of preparation of Example 1, an SiH-functional siloxane of the empirical formula Me.sub.3SiO[SiMe.sub.2O].sub.20[SiMeHO].sub.5.5SiMe.sub.3 was first prepared and then reacted in a hydrosilylation reaction with a polyether of the empirical formula CH.sub.2═CHCH.sub.2O[C.sub.2H.sub.5O].sub.12.5[CH.sub.2CH(CH.sub.3)O].sub.3.3H. The reaction product obtained was a polyether-modified siloxane of the empirical formula Me.sub.3SiO[SiMe.sub.2O].sub.20[SiMeR.sup.2O].sub.5.5SiMe.sub.3 with R.sup.2=—CH.sub.2CH.sub.2CH.sub.2O[C.sub.2H.sub.5O].sub.12.5[CH.sub.2CH(CH.sub.3)O].sub.3.3H.

Production and Examination of the Dressed Seeds

[0083] The seed dressings (seed-dressing liquors, dressings) were blended with the additives to be examined for their dust-reducing effect by simply blending water and a commercial suspension concentrate for seed treatment for wheat and barley (Landor® CT from Syngenta). Additives examined were the polyether-modified siloxane from Example 1 and 2, a commercially available polyether-modified siloxane from Momentive (Example 3), the commercially available anti-dusting agent MaximalFlow® from BASF (Example 4), and a further additive based on a silicone oil emulsion (Example 5). The Landor® CT suspension concentrate used is a mixture of fludioxonil, difenoconazole and tebuconazole for treatment of seed, for example wheat and barley. It was used in the customary amount of 200 ml per 100 kg of seed. The amount of water used was likewise 200 ml per 100 kg of seed.

[0084] The amounts of the additives used can be found in Table 1. MaximalFlow® (Example 4) was used in the amount recommended by the manufacturer of 20 ml per 100 kg of seed. The polyether-modified polyethersiloxanes were correspondingly likewise used at 20 ml per 100 kg of seed, and Example 1 additionally also at 10 ml per 100 kg of seed. The silicone oil-based additive of Example 5 (a 35% silicone oil emulsion) was used in an amount of 60 ml per 100 kg of seed. The seed-dressing liquors thus produced were applied to 1 kg of seed (wheat) in each case by means of a standard seed-dressing system (mixing system based on the rotor-stator principle). Subsequently, by means of the Heubach test, the dust values reported in g of dust per 100 kg of seed were determined (see Table 1).

TABLE-US-00001 TABLE 1 Compositions of the seed-dressing liquors (dressings) (stated amounts of the components in ml per 100 kg of seed); dust values of the dressed seeds according to Heubach test (figures in g of dust per 100 kg of seed, ESA 11.0387, ch. 5.7) Dressings 0 1a 1b 2 3 4 5 Example 1 10 20 Polyether-modified siloxane Me.sub.3SiO[SiMe.sub.2O].sub.38[SiMeR.sup.2O].sub.10SiMe.sub.3 with R.sup.2 = CH.sub.2CH.sub.2CH.sub.2O[C.sub.2H.sub.5O].sub.13.9[CH.sub.2CH(CH.sub.3)O].sub.5.3H Example 2 20 Polyether-modified siloxane Me.sub.3SiO[SiMe.sub.2O].sub.20[SiMeR.sup.2O].sub.5.5SiMe.sub.3 with R.sup.2 = CH.sub.2CH.sub.2CH.sub.2O[C.sub.2H.sub.5O].sub.12.5[CH.sub.2CH(CH.sub.3)O].sub.3.3H Example 3 20 Polyether-modified trisiloxane Silwet ® L 77 (Momentive) * Example 4 20 Silicone oil emulsion ** MaximalFlow ® (BASF) Example 5 60 Silicone oil emulsion *** Landor ® CT (Syngenta) 200 200 200 200 200 200 200 Water 200 200 200 200 200 200 200 Dust value (Heubach test) 0.7 0.1 0.03 0.3 0.4 0.2 0.4 * Trisiloxane Me.sub.3SiO[SiMeR.sup.2O]SiMe.sub.3 where R.sup.2 is based on an allyl alcohol-started polyether having ethyleneoxy units and having a number-average molar mass M.sub.N of about 400 g/mol. This corresponds to a compound of the formula Me.sub.3SiO[SiMeR.sup.2O]SiMe.sub.3 with R.sup.2 = —CH.sub.2CH.sub.2CH.sub.2O[C.sub.2H.sub.5O].sub.7.8H ** according to manufacturer data contains a silicone oil emulsion (479 g/l) and a polymer dispersion based on acrylic esters (478 g/l) *** contains 35% by weight of silicone oil (polydimethylsiloxane having a kinematic viscosity of 40 000 mm.sup.2/s), 10% emulsifier (HLB about 12-13) and 45% by weight of water

[0085] The reference example without further additive (dressing 0) already leads to very low dust values of 0.7 g per 100 kg of seed. Frequently, dust values exceeding 1 g per 100 kg of seed or even 2 g per 100 kg of seed are found. The additives from Examples 1 to 5 can lower the dust value further. These additives are thus all suitable as anti-dusting agents. In the case of the polyether-modified siloxanes (Examples 1 to 3) examined, it is observed that the more silicon atoms the polyether-modified siloxane has, the lower the evolution of dust. The polyether-modified siloxane having the highest number of silicon atoms (Example 1) correspondingly shows the lowest dust value. The polyether-modified siloxanes also have the advantage that the mixing drum of the seed-dressing system can be cleaned with water without difficulty, i.e. all residues of the dressing are easy to remove. By contrast, Examples 4 and 5 based on silicone oil emulsions present difficulties here since the silicone oil present leads to tacky residues that are difficult to remove.