U.S. patent number RE33,670 [Application Number 06/716,051] was granted by the patent office on 1991-08-20 for granular pesticide composition.
This patent grant is currently assigned to ATOCHEM North America, Inc.. Invention is credited to Michael J. Maglio.
United States Patent |
RE33,670 |
Maglio |
August 20, 1991 |
Granular pesticide composition
Abstract
A granular pesticide composition is prepared by reacting
polyvinyl alcohol, pesticide, a borate, and optional filler(s) in
water until a gel is formed, drying the gel, and then grinding the
product to the desired particle size. The product is then applied
to the soil for controlling pests.
Inventors: |
Maglio; Michael J. (Glenolden,
PA) |
Assignee: |
ATOCHEM North America, Inc.
(Philadelphia, PA)
|
Family
ID: |
27031298 |
Appl.
No.: |
06/716,051 |
Filed: |
March 26, 1985 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
437381 |
Oct 28, 1982 |
04440746 |
Apr 3, 1984 |
|
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Current U.S.
Class: |
424/408; 424/486;
428/402.24; 514/64; 514/86; 514/89; 514/127; 514/128; 514/132;
514/141; 514/646; 514/772.2; 514/951; 514/965 |
Current CPC
Class: |
A01N
25/10 (20130101); Y10T 428/2989 (20150115) |
Current International
Class: |
A01N
25/10 (20060101); A01N 025/12 (); A61K 009/16 ();
B01J 013/20 () |
Field of
Search: |
;424/78,486,408
;428/402.24 ;514/64,951,965 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Lovering; Richard D.
Parent Case Text
.Iadd.This is an application for reissue of U.S. Pat. No. 4,440,746
granted Apr. 3, 1985. .Iaddend.
Claims
What is claimed:
1. A granular slow release soil pesticide composition
.Iadd.comprising by weight based on the total composition of from
about 5 to about 90% of polyvinyl alcohol, from about 1 to about
20% of a borate, from about 2 to about 50% of a compatible
pesticide, and 0 to about 80% of filler(s) .Iaddend.prepared by
mixing .[.from about 5 to about 90% by weight of.]. (.Iadd.a)
.Iaddend.an aqueous solution of polyvinyl alcohol .Iadd.wherein the
solids concentration of polyvinyl alcohol is about 10% .Iaddend.and
.[.from about 2 to about 50% of.]. a compatible pesticide .[.plus 0
to about 80% of.]. .Iadd.and optionally .Iaddend.at least one
filler selected from the class consisting of diatomites,
attapulgites, bentonites, talcs, montmorillonites, perlites,
vermiculites, calcium carbonates, corn cob grits, wood flour,
lignin sulfonates, and mixtures thereof with .[.from about 1 to
about 20% of.]. (.Iadd.b) .Iaddend.a borate until .[.said.].
ingredients (.Iadd.a) and (b) .Iaddend.react to form a gel, drying
the gel, and grinding the dried product to the desired particle
size.
2. The composition of claim 1 wherein the pesticide is selected
from the group consisting of chlorpyrifos, chlorpyrifos-methyl,
diazinon, fonofos, parathion, fensulfothion, methyl parathion,
phorate, and trifluralin.
3. The composition of claim 1 wherein the product is ground to pass
through a number 14 mesh screen but is retained on a number 40 mesh
screen.
4. A method of controlling pests comprising applying an effective
amount of the composition of claim 1 to soil. .Iadd.5. A method of
encapsulating a pesticide comprising the steps of:
a. preparing a solution or dispersion of such pesticide in a
matrix-forming material comprising an aqueous solution of a
gel-forming polyvinyl alcohol wherein said aqueous solution has a
solids concentration of said polyvinyl alcohol of about 10%,
wherein the relative amount of said polyvinyl alcohol with respect
to said pesticide is sufficient to entrap said pesticide within a
matrix of said polyvinyl alcohol;
b. reacting said polyvinyl alcohol with a borate to form a
continuous insolubilized matrix gel having entrapped therein
uniformly dispersed, discontinuous domains of said pesticide;
and
c. recovering free-flowing particles of said entrapped pesticide.
.Iaddend. .Iadd.6. A composition of matter produced by the process
of claim 5. .Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to a composition and method of treating the
soil with a slow release matrix-carried pesticide for controlled,
sustained release of active agents contained within the matrix to
protect plants from damage by various pests. More particularly, the
invention comprehends the use of a polyvinyl alcohol (PVA)-borate
based release system for pesticides applied to the soil. U.S. Pat.
No. 4,110,431 discloses the use of polyvinyl alcohol-borate
complexes formed by water activation of mixtures of the PVA and
borax in situ for attaching plant treatment additives to plane
foliage. Japanese Patent No. 74/48073 describes the use of borax to
harden PVA used in the form of micro-capsules to encapsulate
perfume and flame retardants. South African Patent Nos. 69/00122
and 69/00088 teach the use of PVA-borate capsules for plasticizers
and dyes.
SUMMARY OF THE INVENTION
The present invention is directed to a granular, slow release
matrix-carried pesticide prepared by reacting an aqueous solution
of polyvinyl alcohol and the desired pesticide plus optional
filler(s) with a borate with agitation until the reaction is
complete forming a gel, drying the gel, and grinding the dried
product to the desired particle size. This produce is then applied
to the soil where it slowly releases the pesticide for controlling
the desired pest.
DETAILED DESCRIPTION OF THE INVENTION
The present invention requires a water soluble polyvinyl alcohol, a
borate, and optional filler(s). When the pesticide-containing
polyvinyl alcohol solution and the borate are combined, they form a
didiol complex, as indicated below: ##STR1## The reaction mixture
thereby gels and entraps the pesticide in a matrix. The matrix is
freed from water by drying, and then further refined by grinding
and screening to the desired particle size. Granulates in the 14-40
mesh range are preferred.
Any pesticide which is compatible with the matrix can be employed
for the present invention. Typical examples are chlorpyrifos,
chlorpyrifos-methyl, methyl parathion, parathion, diazinon,
fonofos, fensulfothion, phorate, trifluralin, etc., which can be
used undiluted, in the form of suited solutions, on fillers, or in
combinations.
As far as polyvinyl alcohol is concerned, any water soluble grade
can be used in the practice of this invention. Suited typical
commercial products are the various partially or fully hydrolyzed
polyvinyl acetates sold in various molecular weight ranges under
the trade names of Gelvatol, Vinol, Elvanol, etc. Preferred are
products which are characterized by high solubility/low viscosity
in water.
For effecting gelation of PVA, various sources of borate ions can
be used. Suited materials are alkali metal, alkaline earth metal
and ammonium salts of borate anions such as tetraborate and
metaborate anions. Examples are sodium borate (borax), sodium
metaborate, and potassium borate. Also combinations of boric acid
and alkalizing agents are effective.
With respect to optional filler(s), a large variety of powdered or
granular materials can be employed in the practice of this
invention. Examples are various diatomites, attapulgites,
bentonites, talcs, montmorillonites, perlites, vermiculites,
calcium carbonates, corn cob grits, wood flour, lignin sulfonates,
etc.
The amounts of the various ingredients in the total formulation can
vary widely, and range from about 5-90% (by weight) of PVA, 2-50%
of the active ingredient(s), 0-80% of the filler(s), and 1-20% of
borate. Preferred ranges are: 5-70% of PVA, 5-30% of active
ingredient(s), and 30-80% of filler(s). The amount of borate
required to effect gelation varies with the type and amount of PVA
and filler(s) used in the particular formulation and is best
determined experimentally.
EXAMPLE I
Twenty grams of PVA (marketed by the Monsanto Corporation under the
tradename Gelvatol 9000) were dissolved in 180 grams of deionized
water to yield 200 grams of a 10% PVA solution. Ten grams of a
technical grade methyl parathion (76% active) was dispersed in the
10% PVA solution. Twenty-one grams of a 10% sodium borate (borax)
in water solution was then added to the PVA-methyl parathion
dispersion and reacted with stirring until an opaque gel formed.
The PVA-methyl parathion gel was dried in a forced air oven at
55.degree. C. for 16 hours, yielding 29.7 grams of product. The
dried product was then ground in a blender to a particle size that
would pass through a number 14 mesh screen but remained on a number
40 mesh screen. This particulate material was found to contain
25.1% active ingredient.
EXAMPLE II
Eight grams of Gelvatol 9000 were dissolved in 72 grams deionized
water yielding 80 grams of a 10% PVA solution. Into this 5 grams of
Dursban XM (a commercial chlorpyrifos at 65% active ingredient) was
dispersed. Three grams of sodium borate (borax) were then dissolved
in 15 grams of water and added to the PVA-Dursban XM dispersion and
reacted until a gel precipitate formed. This gel precipitate was
then dried in an exhaust hood for 24 hours to yield 14.2 grams of
product. The dried product was then ground to a particle size that
would pass through a number 14 mesh screen but yet remained on a
number 40 mesh screen. The granular product was found to contain
14.5% active ingredient.
EXAMPLE III
Five grams of Gelvatol 9000 were dissolved in 45 grams deionized
water. To this solution 19.0 grams of methyl parathion-loaded
Diatomite [prepared by soaking 13.5 grams of Celatom MN-39 (Eagle
Pitcher) with 4.5 grams technical methyl parathion in .about.40
grams methylene chloride, and removing volatile components at
.about.50.degree. C./130 mm Hg] were added, followed by dropwise
addition of 5 grams of warm 10% borax solution. The resulting gel
was dried in an exhaust hood for 24 hours, and then in an oven at
.about.75.degree. C. for 21/2 hours. The dry product (23.4 grams)
was ground in a blender and then classified to yield 14.3 grams
product of 14-40 mesh size. It contained 13.2% active
ingredient.
EXAMPLE IV
The granular product of Example I was tested in a laboratory soil
bioassay using 3 day oid housefly larvae as test organisms.
Twenty-five housefly larvae were exposed to soil at intervals of 3,
10, 17, 38, and 45 days following treatment with the granular
product and the number of adult flies emerging from the soil was
counted. The granular product was used at a rate equivalent to 1/2
pound of active ingredient per acre applied in 6" bands spaced 40"
apart.
For the sake of comparison, a commercial formulation of methyl
parathion was also tested at the same level of active ingredient
and the results of both products were recorded in Table I. %
Control is defined as the percent reduction in adult housefly
emergence.
TABLE I ______________________________________ % Control 3 10 17 38
45 ______________________________________ PVA Matrix 39.0 93.8 91.9
65.3 76.4 Methyl Parathion EC 21.0 10.4 14.9 3.9 0.0 Control 0.0
4.0 1.3 10.7 23.4 ______________________________________
EXAMPLE V
The granular product of Example II was then tested for bioactivity
in soil as in Example IV.
For the sake of comparison, a commercial formulation of
chlorpyrifos (Lorsban.RTM. 15G) was tested. The results of both
products were recorded in Table II as follows:
TABLE II ______________________________________ % Control 3 10 17
24 31 ______________________________________ PVA Matrix 97.9 98.0
96.9 80.7 75.0 Lorsban 15G 91.4 96.0 96.9 68.6 39.6 Control 6.7 0.0
4.0 1.3 6.0 ______________________________________
EXAMPLE VI
In the laboratory soil bioassay with 3 day old housefly larvae, the
product of Example III showed the following activity as compared to
the methyl parathion-loaded filler without PVA matrix:
TABLE III ______________________________________ % Control 3 17 31
45 ______________________________________ PVA Matrix 84.3 60.9 74.0
72.0 MP-loaded Filler 94.8 57.9 54.0 0 Control 4.0 2.7 0 10.7
______________________________________
As evident, the PVA matrix formulation exhibited a much
longer-lasting insecticidal activity than a comparable formulation
without the matrix.
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