United States Patent (19
`Yamada et al.
`
`|||||IH
`USOO5488043A
`5,488,043
`11
`Patent Number:
`(45) Date of Patent:
`Jan. 30, 1996
`
`54) METHOD FOR STABILIZING ACEPHATE
`AND A DRY PESTICDAL FORMULATION
`CONTAINING THE STABILIZED ACEPHATE
`
`75 Inventors: Masahiro Yamada, Takarazuka;
`Yasuyuki Katayama, Toyonaka,
`Toshiro Ohtsubo, Sanda, all of Japan
`73) Assignee: Sumitomo Chemical Co., Ltd., Osaka,
`Japan
`
`21 Appl. No.: 360,042
`(22
`Filed:
`Dec. 20, 1994
`30
`Foreign Application Priority Data
`Dec. 20, 1993
`JP
`Japan .................................... 5-319595
`May 9, 1994
`JP
`Japan .................................... 6-094.813
`(51] Int. Cl. ......................................... AON 57/28
`52 U.S. Cl. ............................. 514/120; 558/71; 558/178
`58) Field of Search ............................... 514/120; 558/71,
`558/178
`
`56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`5,352,674 10/1994 Cummings .............................. 514/120
`FOREIGN PATENT DOCUMENTS
`0304492 3/1989 European Pat. Off..
`5867603 10/1981 Japan.
`Primary Examiner-Richard L. Raymond
`Attorney, Agent, or Firm-Sughrue, Mion, Zinn, Macpeak &
`Seas
`ABSTRACT
`(57)
`The present invention relates to a method for stabilizing
`acephate which comprises adding a sodium salt of con
`densed phosphate and/or a synthetic silicic acid in which the
`Surface silanol groups being alkylsilylated to acephate or
`acephate-containing dry pesticidal formulation and a stabi
`lized acephate having added a sodium salt of condensed
`phosphate and/or a synthetic silicic acid in which the surface
`silanol groups being alkylsilylated.
`13 Claims, No Drawings
`
`

`

`1.
`METHOD FOR STABLIZING ACEPHATE
`AND A DRY PESTCDAL FORMULATION
`CONTAINING THE STABLIZED ACEPHATE
`
`5,488,043
`
`2
`The amount of the sodium salt of condensed phosphate
`useful for stabilization of acephate is generally 0.01 to 10
`parts by weight, preferably 0.05 to 1 part by weight to one
`part by weight of acephate.
`The amount of the synthetic silicic acid in which the
`surface silanol groups being alkylsilylated which is useful
`for stabilization of acephate is generally 0.05 parts by weight
`or more, preferably 0.05 to 10 parts by weight to one part by
`weight of acephate.
`The content of acephate in the dry pesticidal formulation
`of the present invention is generally 0.5 to 99% by weight,
`preferably 5 to 95% by weight. The content of the sodium
`salt of condensed phosphate in the dry pesticidal formulation
`is an amount in which acephate may be stabilized, usually
`0.01 to 50% by weight, preferably 1 to 20% by weight, more
`preferably 1 to 10% by weight. The content of the synthetic
`silicic acid in which the surface silanol groups being alkyl
`silylated is an amount in which acephate may be stabilized,
`usually 1 to 99% by weight.
`The dry pesticidal formulation using the sodium salt of
`condensed phosphate may usually contain a solid carrier for
`pesticidal formulation in addition to acephate and sodium
`salt of condensed phosphate. Said solid carriers include, for
`example, a mineral carrier such as kaolin clay, attapulgite
`clay, sericite clay, pyrophyllite clay, montmorillonite clay,
`zeolite, bentonite, acid clay, activated clay, serpentine, talc
`and diatomaceous earth, an inorganic salt such as sulfate,
`nitrate, chloride and carbonate, an inorganic carrier such as
`a synthetic carrier (e.g., silica), or an organic carrier such as
`Sugars, starch, dextrin, flour, soy meal, corn meal and wood
`powder.
`The dry pesticidal formulation of the present invention
`using the synthetic silicic acid in which the surface silanol
`groups being alkylsilylated may be ones consisting of aceph
`ate and the synthetic silicic acid in which the surface silanol
`groups being alkylsilylated, but additionally a solid carrier
`for the preparation may be contained therein. Said solid
`carriers include, for example, ones as mentioned above.
`The solid carrier may be usually contained in 1 to 90%
`by weight, preferably 20 to 70% by weight in the dry
`pesticidal formulation.
`The dry pesticidal formulation of the present invention
`may contain auxiliaries for pesticidal formulation, for
`example, at least one selected from the group consisting of
`surface active agent, coloring matter, perfume and known
`stabilizer, which are usually contained in 0.1 to 35% by
`weight, preferably 2 to 10% by weight.
`The surface active agents that can be used in the present
`invention includes, for example, anionic surface active
`agents such as alkyl sulfates (e.g., sodium lauryl sulfate),
`alkylaryl sulfonates (e.g., sodium alkylnaphthalene sul
`fonate), lignin sulfonates (e.g., sodium lignin sulfonate),
`succinic acid ester derivative, polycarbonate, polyethyleneg
`lycol alkylaryl ether sulfonate and a formaldehyde conden
`sate of aromatic sulfonate, or nonioinic surface active agents
`such as polyoxyethylene alkylether, polyoxyethylene alky
`larylether and polyoxyethylene arylarylether.
`The dry pesticidal formulation of the present invention
`may additionally contain other pesticidal active ingredients,
`for example, pyrethroid compound such as Fenpropathrin,
`Fenvalerate and Esfenvalerate.
`The dry pesticidal formulation of the present invention
`may be in the form of, for example, dust, driftless dust,
`wettable powder, water soluble powder, granule, water
`soluble granule, water dispersible granule, dry flowable,
`tablet or pellet, and these dry pesticidal formulations may be
`used by packaging those in a packaging container such as
`water soluble pack.
`
`The present invention relates to a method for stabilizing
`acephate and a dry pesticidal formulation containing the
`stabilized acephate.
`Acephate (O, S-dimethyl acetylphosphoramidothioate) is
`a known compound having an insecticidal activity as
`described on page 1 of The Pesticide Manual 8th edition
`(published by The British Crop Protection Council, 1987)
`and used as an active ingredient for agricultural insecticide
`now, because of having effective controlling activities to
`various pests.
`On the contrary to other organic phosphoric compounds
`having an insecticidal activity, acephate has a lower stability
`in a pesticidal formulation. Accordingly, acephate in the
`formulation is vigorously decomposed depending on the
`storage condition and the activity of acephate could not be
`often exhibited efficiently. Under the circumstances, there
`has been demanded a method for imparting a stability to
`acephate in the formulation and development of such a
`pesticidal composition which is capable of exhibiting the
`pesticidal activity of acephate efficiently.
`The present inventors have conducted extensive study of
`such a subject matter. As a result, they have discovered that
`a sodium salt of condensed phosphate and/or a synthetic
`silicic acid in which the surface silanol groups being alkyl
`silylated may improve the stability of acephate in a dry
`formulation and the present invention has been completed.
`Therefore, the present invention relates to a method for
`stabilizing acephate by adding an effective amount of a
`sodiums salt of condensed phosphate and/or an effective
`amount of a synthetic silicic acid in which the surface silanol
`groups being alkylsilylated, to the acephate, a method for
`stabilizing acephate in a dry formulation by mixing acephate
`with an effective amount of a sodium salt of condensed
`phosphate and/or an effective amount of a synthetic silicic
`acid in which the surface silanol groups being alkylsilylated
`and a dry pesticidal formulations containing acephate and an
`effective amount of a sodium salt of condensed phosphate
`and/or an effective amount of a synthetic silicic acid in
`which the surface silanol groups being alkylsilylated. -
`In the context of the present invention, the sodium salt of
`condensed phosphate refers to a compound in which two or
`more sodium phosphates are condensed via an oxygen atom,
`for example, sodium polyphosphate, sodium tripolyphos
`phate or sodium pyrophosphate.
`The synthetic silicic acid in which the surface silanol
`groups being alkylsilylated used in the present invention
`may be usually prepared by alkylsilylating the surface
`silanol groups of a synthetic silicic acid produced by the wet
`process obtained by adding a mineral acid such as hydro
`chloric acid and sulfuric acid to an aqueous sodium silicate
`solution or of a synthetic silicic acid produced by the dry
`process obtained by decomposing silicon tetrachloride with
`an oxyhydrogen flame etc. with dialkyldichlorosilane or
`alkyltrichlorosilane. Said alkyl group is usually a lower
`alkyl group such as methyl and ethyl and the number of the
`surface silanol group is usually reduced substantially to 3 or
`lesslnm'. The synthetic silicic acid in which the surface
`silanol groups being alkylsilylated thus obtained is commer
`cially available as Carplex(8 CS-701 mfg. by Shionogi
`Pharmaceuticals, Carplex(R) CS-801 mfg. by Shionogi Phar
`maceuticals, Reolosil(8) MT-10 mfg. by Tokuyama Soda,
`Aerosil(R) R972 mfg. by Degussa, Sipernat(8) D 17 mfg. by
`Degussa or SipernatCE) D 10 mfg. by Degussa.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`

`

`5,488,043
`
`3.
`The dry pesticidal formulation of the present invention
`may be prepared according to a conventional method, for
`example, by admixing acephate and sodium salt of con
`densed phosphate and/or synthetic silicic acid in which the
`surface silanol groups being alkylsilylated, additionally a
`solid carrier and auxiliaries such as a surfactant if necessary
`in a mixer, pulverizing the mixture with a grinder Such as
`air-mill, hammer mill, jet pulverizer and centrifugal pulver
`izer into, for example 20 um or less of average particle size
`to obtain a powdery pesticidal formulation of the present
`invention, alternatively molding those pulverized mixture
`into granules using a compression press such as a roller
`compactor, extrusion granulator, pan granulator, fluidized
`bed granulator or rolling granulator to obtain a dry pesticidal
`formulation of the present invention.
`The present invention will be explained with reference to
`the following formulation examples and test examples in
`detail, but the invention should not be construed as being
`limited to these examples only.
`
`FORMULATION EXAMPLE 1.
`25 Parts by weight of acephate, 5 parts by weight of
`sodium tripolyphosphate, 4 parts by weight of sodium
`dodecylbenzenesulfonate, 2 parts by weight of sodium aryl
`sulfonate formaldehyde condensate, 20 parts by weight of
`Tokusilo) GU-N (synthetic silicic acid mfg. by Tokuyama
`Soda), and 44 parts by weight of kaolin clay were pulverized
`with a jet pulverizer and mixed in a mixer to obtain a
`wettable powder which is a dry pesticidal formulation of the
`present invention.
`
`FORMULATION EXAMPLE 2
`A wettable powder of the present dry pesticidal formula
`tion was obtained according to Formulation Example 1,
`except that 10 parts of sodium tripolyphosphate were used
`instead of 5 parts of sodium tripolyphosphate and 39 parts of
`kaolin clay were used instead of 44 parts of kaolin clay.
`
`4
`trolled container set at a specified temperature. The content
`of acephate before and after storage was determined with a
`gas chromatography, and the decomposition rate was calcu
`lated according to the following equation:
`content of acephate
`after storage
`Decomposition rate (%)= 100-100X content of acephate
`before storage
`
`10
`
`15
`
`Tables 1, 2 and 3 show the results.
`
`TABLE 1.
`Decomposition rate (%)
`40° C.
`
`Assayed Formulation
`
`after 1 month
`
`after 3 months
`
`Formulation Example I
`Formulation Example 2
`Comparative Formulation
`Example 1
`
`20
`
`O
`1
`4.
`
`16
`13
`31
`
`25
`
`TABLE 2
`Decomposition rate (%)
`50° C.
`
`Assayed Formulation
`
`after 2 weeks
`
`after 1 month
`
`30
`
`Formulation Example 1
`Formulation. Example 2
`Comparative Formulation
`Example 1
`
`3
`2
`5
`
`26
`20
`44
`
`35
`
`TABLE 3
`Decomposition rate (%)
`50° C.
`
`FORMULATION EXAMPLE 3
`40
`25 Parts by weight of acephate, 20 parts by weight of
`Carplex(). CS-701, 4 parts by weight of sodium dodecyl
`benzenesulfonate, 2 parts by weight of sodium arylsulfonate
`formaldehyde condensate and 49 parts by weight of kaolin
`clay were pulverized with a jet pulverizer and mixed in a
`mixer to obtain a wettable powder which is the present dry
`pesticidal formulation.
`
`45
`
`COMPARATIVE FORMULATION EXAMPLE 1.
`Comparative Formulation 1 was obtained according to
`Formulation Example 1, except that 5 parts by weight of
`kaolin clay were used instead of 5 parts by weight of sodium
`tripolyphosphate.
`
`50
`
`COMPARATIVE FORMULATION EXAMPLE 2
`Comparative Formulation 2 was obtained according to
`Formulation Example 3, except that 20 parts by weight of
`Tokusil(E) GU-N (synthetic silicic acid mfg. by Tokuyama
`Soda) were used instead of 20 parts by weight of Carplex(8)
`CS-701.
`
`55
`
`60
`
`TEST EXAMPLE
`Each formulation obtained by said Formulation Examples
`and Comparative Formulation Examples was enclosed in an
`aluminum-laminated bag and stored in a temperature con
`
`65
`
`Assayed Formulation
`
`after 2 weeks
`
`after 1 month
`
`Formulation Example 3
`Comparative Formulation
`Example 2
`
`1
`6
`
`8
`33
`
`We claim:
`1. A method for stabilizing acephate which comprises
`adding an effective amount of a sodium salt of condensed
`phosphate and/or an effective amount of a synthetic silicic
`acid in which the surface silanol groups being alkylsilylated,
`to acephate.
`2. A method for stabilizing acephate in a dry formulation
`which comprises mixing acephate with an effective amount
`of a sodium salt of condensed phosphate.
`3. A method according to claim 2 wherein the weight ratio
`of acephate to sodium salt of condensed phosphate is
`1:0.01-1:10.
`4. A method for stabilizing acephate in a dry formulation
`which comprises mixing acephate with an effective amount
`of a synthetic silicic acid in which the surface silanol groups
`being alkylsilylated.
`5. A methyl according to claim 4 wherein the weight ratio
`of acephate to the synthetic silicic acid in which the surface
`silanol groups being alkylsilylated is 1:0.05-1:10.
`6. A dry pesticidal formulation comprising acephate and
`an effective amount of a sodium salt of condensed phosphate
`and/or an effective amount of a synthetic silicic acid in
`which the surface silanol groups being alkylsilylated.
`
`

`

`5,488,043
`
`5
`7. A dry pesticidal formulation comprising acephate and
`an effective amount of a sodium salt of condensed phos
`phate.
`8. A dry pesticidal formulation comprising acephate and
`an effective amount of a synthetic silicic acid in which the
`surface silanol groups being alkylsilylated.
`9. A dry pesticidal formulation according to claim 7
`wherein the weight ratio of acephate to sodium salt of
`condensed phosphate is 1:0.01-1:10.
`10. A dry pesticidal formulation according to claim 8
`wherein the weight ratio of acephate to the synthetic silicic
`acid in which the surface silanol groups being alkylsilylated
`is 1:0.05-1:10.
`
`10
`
`6
`11. A dry pesticidal formulation according to claim 7,
`wherein the formulation is dust, driftless dust, wettable
`powder, water soluble powder, granule, water soluble gran
`ule, water dispersible granule, dry flowable, tablet or pellet.
`12. A dry pesticidal formulation according to claim 7,
`wherein the formulation is dust, driftless dust, water soluble
`powder, granule, water soluble granule, water dispersible
`granule, dry flowable, tablet or pellet.
`13. A dry pesticidal formulation according to claim 8,
`wherein the formulation is dust, driftless dust, wettable
`powder, water soluble powder, granule, water soluble gran
`ule, water dispersible granule, dry flowable, tablet or pellet.
`
`ck
`
`k
`
`k
`
`>k
`
`k
`
`