Plant protecting and regulating compositions – Plant growth regulating compositions – Designated nonactive ingredient containing
Reexamination Certificate
2000-05-18
2001-10-09
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Designated nonactive ingredient containing
C504S363000, C514S772000, C514S937000, C514S975000
Reexamination Certificate
active
06300283
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a novel water-base agrochemical composition containing a unique polyether-modified silicone compound. More particularly, the invention relates to a water-base agrochemical composition containing a unique polyether-modified silicone compound as a spreader agent for the agricultural chemical compound as the effective ingredient in the composition and suitable for spraying over agricultural fields, of which the polyether-modified silicone or organopolysiloxane compound is capable of exhibiting high surface activity in an aqueous medium with good stability over a wide range of the pH value of the water-base agrochemical composition.
It is a very common practice that water-base agrochemical compositions in the form of an aqueous solution or emulsion applied to the plants in the agricultural fields and orchards are almost always formulated with a spreader or tacker in order to improve spreadability of the agrochemical composition with good uniformity over the plants so as to ensure high herbicidal, insecticidal and pesticidal effects.
The spreader agents conventionally formulated in a water-base agrochemical composition are each a surface active agent by which the water-base composition is imparted with a decreased surface tension so as to promote uniform adherence of the agricultural chemical to the body of the plants within a short time. Various types of surface active agents are heretofore proposed and employed as an agrochemical spreader including polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxyethylene higher fatty acid esters.
Besides the above mentioned polyoxyethylene-based surface active agents, silicone-based surface active agents are highlighted in recent years as an agrochemical spreader agent for water-base agrochemical compositions in respect of their high surface activity and low toxicity against human body. For example, Japanese Patent Kokai 6-55642 proposes a silicone-based spreader agent for a water-base agrochemical composition which is an organotrisiloxane compound expressed by the general formula
(Me
3
Si—O—)
2
SiMe—[—C
3
H
6
—O—(—C
2
H
4
—O—)
p
—R],
in which Me is a methyl group, R is a hydrogen atom or a methyl group and the subscript p is a positive integer of 6 to 10.
The applicability of the above defined polyoxyethylene-modified organotrisiloxane compound as an agrochemical spreader agent, however, is very limited because an aqueous solution of the compound exhibits surface activity only when the aqueous solution has a pH at or in the vicinity of neutrality and the surface activity of the aqueous solution thereof is decreased or lost when the solution is acidic or alkaline as is reported in Pesticidal Science, volume 38 (1993), pages 103-122. When the aqueous solution of the silicone compound has a pH value lower than 5 or higher than 9, for example, the surface activity of the aqueous solution is lost within only 24 hours of standing at room temperature. Reportedly, the mechanism for this surface activity degradation is presumably that a siloxane-rearrangement disproportionation reaction takes place in the molecules of the trisiloxane compound resulting in the formation of hexamethyl disiloxane on one hand and a diorganopolysiloxane of a larger molecular weight on the other hand. Accordingly, it is usually important that the spreader-formulated water-base agrochemical composition is prepared by admixing the silicone compound, immediately before use of the composition in the fields, to a master composition or that the pH value of the spreader-formulated water-base composition is kept at or around neutrality by using a suitable buffer solution.
It is sometimes the case, however, that a spreader-formulated water-base agrochemical composition can not always be actually employed just after preparation by the admixture of the silicone compound, for example, due to a sudden change in the weather for raining necessitating postponing of actual application of the ready-prepared composition which must be replaced with a new preparation when the weather is recovered. The use of a buffer solution to ensure neutrality of the water-base composition is also not free from a serious disadvantage because the agricultural chemical compound as the effective ingredient of the water-base composition is necessarily limited to those compounds having stability at neutrality since even weak acidity or weak alkalinity of the water-base composition is detrimental against stability of the compound.
SUMMARY OF THE INVENTION
The present invention accordingly has an object, in view of the above described problems and disadvantages relative to the conventional water-base agrochemical compositions containing a surface active agent as a spreader, to provide a novel spreader-containing water-base agrochemical composition in which the effectiveness of the spreader agent can be retained with stability over a long period of time irrespective of the pH value of the water-base composition in a wide range.
Thus, the spreader-containing water-base agrochemical composition provided by the present invention is a uniform blend which comprises:
(a) water as a solvent or dispersion medium;
(b) a chemical compound capable of exhibiting activity as an agricultural chemical in an effective amount as dissolved or dispersed in water as the component (a); and
(c) a polyether-modified organopolysiloxane compound represented by the general formula
R
3
—SiR
1
2
—O—(—SiR
1
2
—O—)
m
—(—SiR
1
R
2
—O—)
n
—SiR
1
2
—R
3
, (I)
In which the subscript m is a positive integer not exceeding 10 and the subscript n is 0 or a positive integer not exceeding 10 with the proviso that m+n is at least 2, R
1
is an alkyl group having 1 to 5 carbon atoms or a phenyl group, R
2
is a polyoxyalkylene-substituted alkyl group of the general formula —C
x
H
2x
—O—(C
2
H
4
O)
y
—(C
3
H
6
O)
z
—R
4
, R
4
being a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or an acetyl group, the subscript x being a positive integer of 2, 3 or 4, the subscript y being a positive integer of 5 to 15 and the subscript z being 0 or a positive integer not exceeding 10, and R
3
is R
1
or R
2
with the proviso that, when the subscript n is 0, at least one of the two R
3
groups in a molecule is R
2
, of which the molecular weight does not exceed 2000 and the weight fraction of the polyoxyethylene units of the formula —(C
2
H
4
O)
y
— is in the range from 30% to 60% by weight as dissolved in water as the component (a) in an amount in the range from 0.005 to 30% by weight based on the total amount of the water-base composition.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As is described above, the water-base agrochemical composition as the object of the present invention, which has been completed as a result of the inventor's extensive investigations to accomplish the above described object of the invention, comprises, as a uniform blend, (a) water as a medium, (b) an effective amount of an agricultural chemical compound as an effective ingredient dissolved or dispersed in water and (c) a limited amount of a polyether-modified organopoly-siloxane compound having a structure represented by the general formula (I) defined above. This unique formulation of the water-base agrochemical composition has been established on the base of the unexpected discovery by the inventor that a silicone compound can be an excellent spreader in a water-base agrochemical composition as desired when and only when the silicone compound has a molecular structure defined by the general formula (I).
The polyether-modified silicone compound as the component (c), which is the most characteristic ingredient in the inventive water-base agrochemical composition, is an organopolysiloxane represented by the general formula (I) and has a molecular weight not exceeding 2000. When the molecular weight thereof exceeds 2000, the organo-polysiloxane compound is inferior as a surface active agent to serve as a spreader agent in a water-base agrochemical composition.
Clardy S. Mark
Millen White Zelano & Branigan P.C.
Shin-Etsu Chemical Co. , Ltd.
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