Dithiocarbamate liquid formulations

Details Dithiocarbamate liquid formulations Dithiocarbamate liquid formulations

2001-11-29

2004-06-22

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S400000

Reexamination Certificate

active

06753003

ABSTRACT:

The invention essentially relates to anhydrous liquid formulations with active ingredients from the class of the dithiocarbamates, in particular metiram. “Essentially anhydrous” means for the purposes of the present invention that the water content is 0 to 5% by weight, in particular 0.1 to 2.5% by weight, and advantageously 0.1 to 1% by weight (in each case based on the total weight of the liquid formulation).
Thiocarbamates, dithiocarbamates, and EBTCs (ethylenebisthiocarbamates) and EBDCs (ethylenebisdithiocarbamates) are generally known as fungicidal active ingredients, in particular as contact fungicides or biocides. Specifically, they are active ingredients such as, for example, metiram, mancozeb, maneb, nabam or else the N,N-dimethylthiocarbamates thiram or ziram.
However, a particular problem of these active ingredients is their relatively high instability. This is caused by the low stability of the C-S and S-S bonds and of the thiocarbamate function, in particular at low pH values and to nucleophilic agents.
A possibility for stable formulations for crop protection is to process the materials as solid formulations. Solid powder formulations which are known are, for example, Manzate 200 75 WG (product of DuPont), Polyram DF (product of BASF AG) and Vondozeb 75 WG (product of Elf Atochem).
DE-A 33 38 979 discloses the stabilization of polyethylenethiuram disulfides by means of formaldehyde or paraformaldehyde. Moreover, DE-A 34 26 078 describes the stabilization of, for example, Zineb by means of calcium oxide. Also, EP-A 0 568 378 discloses the use of EBDC formulations in the form of aqueous granules with improved flowability.
In such formulations, the undesired degradation product by-product ethylene thiourea (ETU) needs careful consideration, owing to its high toxicity. It is important to lower the ETU content under defined threshold values by stabilization measures, for example using hydroxymethane sulfinate (HMS) or a salt thereof, see EP-A-460 612.
In many cases, liquid products are preferred nowadays to the abovementioned solid. formulations. The liquid products have the advantage that they show good miscibility with oily tankmix additives, such as, for example, the so-called Spraytex oil, a paraffin derivative (product of Exxon) for a water/oil or pure oil application, even under ULV (ultra-low volume) conditions; see EP-A-435 760 and EP-A 697 171.
Such ULV conditions, or ULV oil/water mixtures, are particularly important for aerial application. Using aircraft, it is possible to apply relatively low application rates per hectare, approximately 10 to 30 l of the fungicidal active ingredient or of the corresponding formulation, in such a fashion that the effect is reliable and drift is low. Target crops which are typically suitable for such an aerial application of EBDCs are, in particular, bananas and coffee. Aerial application, or ULV application, is done for virtually all banana plantations.
In such an application, it is in particular the so-called oil SC variants (SC=suspension concentrate) of the formulations which are advantageous since they are generally distinguished in the tankmix by good miscibility with spray oils. The oil component improves the rainfastness upon use of the formulations during the tropical rainy season. Oil SC formulations which have proved themselves in this context are, for example, those with the active ingredient mancozeb. Commercially available oil SC formulations with the active ingredient mancozeb are, for example, Dithane 35 SC, Ridodur 35 SC (product of Laquinsa), Vondozeb 35 SC (product of Elf Atochem). Formulations of this type frequently comprise, as dispersant, an oil-soluble polymer, see U.S. Pat. Nos. 3,131,119, 3,773,976 and EP-A 875 142. EP-A 245 970 discloses the use of water-soluble, nonionic polymers to improve the rainfastness of the formulations.
However, storage stability is still unsatisfactory, even with these formulations. This applies in particular if the less stable active ingredient metiram, which comprises Zn as metal ion, is to be employed in place of the active ingredients mancozeb or Maneb, which are relatively stable. This is why liquid formulations with this active ingredient have not been disclosed as yet. However, metiram/oil SC formulations would be advantageous over mancozeb, owing to the higher zinc content of metiram, since it is known that even simple zinc salts already have a fungicidal, or biocidal, action.
On the other hand, the known liquid EBTC/oil SC formulations have even more disadvantages. Firstly, their active ingredient component is lower compared with the solid products. This is because, in oil SC formulations, sufficiently low viscosities are generally achieved when the solid component amounts to less than 40%. If not, there is a danger of the products no longer being sufficiently flowable because of unduly high viscosity.
A further disadvantage of the existing oil SC formulations, in particular oil SC formulations with active ingredients from the class of the EBTCs, is that such formulations frequently only have unsatisfactory rheological properties after storage. Thus, storage at elevated temperatures frequently leads to agglomeration effects, lump formation or pronounced settling of the solid phase. In some cases, the effects are even irreversible, i.e. even renewed shearing, for example by stirring, cannot rehomogenize the formulations.
It is an object of the present invention to provide essentially anhydrous liquid formulations with an active ingredient from the class of the dithiocarbamates, in particular metiram-comprising liquid formulations, which exhibit a high active ingredient content per liter, a low viscosity and high storage stability. It is also an object of the present invention to provide a process for the preparation of such essentially anhydrous liquid formulations.
We have found that this object is achieved in a first aspect of the invention by an essentially anhydrous liquid formulation comprising:
a) 10 to 70% by weight, preferably 30 to 60% by weight, of at least one active ingredient from the class of the dithiocarbamates,
b) 10 to 89% by weight, preferably 20 to 60% by weight, of the abovementioned essentially anhydrous oil phase,
c) 1 to 40% by weight, preferably 5 to 20% by weight, of a product selected from polyhydroxystearic acid, a derivative thereof, an alkyl or alkenyl polyether alkoxylate or a mixture thereof,
d) 0 to 40% by weight, preferably 0 to 10% by weight of at lest one anionic surfactant,
(in each case based on the total weight of the formulation).
A second aspect of the invention provides an essentially anhydrous liquid formulation comprising:
a) 10 to 70% by weight, preferably 30 to 60% by weight, of at least one active ingredient of the formula I hereinbelow
 in which Me=Zn, 1≦×≦5,
b) 10 to 85% by weight, preferably 20 to 60% by weight, of an essentially anhydrous oil phase,
c) 5 to 40% by weight, preferably 7.5 to 25% by weight, of at least one anionic surfactant,
(in each case based on the total weight of the formulation).
In the abovementioned liquid formulation, the value for x is, in particular, in a range of 3 to 4.
Liquid formulation of the first aspect of the invention:
The dithiocarbamate active ingredients thus include the thiuram sulfides. Preferred active ingredients are ziram (zinc dimethyldithiocarbamate), thiram (tetramethylthiuram disulfide) and metham (sodium methyldithiocarbamate). Other preferred compounds are those of the formula (II),
in which:
Me is a mono- or divalent agriculturally utilizable metal ion, in particular selected from amongst Zn, Mn, Na, Mg, Ca and/or K, preferably Zn and/or Mn, and 1≦×≦4, preferably 3≦×≦4, and y is 1 or 2, depending on the valence of Me.
These active ingredients are, in particular, maneb (manganese ethylenebisdithiocarbamate), mancozeb (the coordination product of maneb with zinc ions), nabam (sodium ethylenebisdithiocarbamate), zineb (zinc ethylenebisdithiocarbamate) and, preferably, metiram (compound of the formula I where x&

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