CA1056724A - Insect-combatting device - Google Patents
Insect-combatting deviceInfo
- Publication number
- CA1056724A CA1056724A CA264,454A CA264454A CA1056724A CA 1056724 A CA1056724 A CA 1056724A CA 264454 A CA264454 A CA 264454A CA 1056724 A CA1056724 A CA 1056724A
- Authority
- CA
- Canada
- Prior art keywords
- naled
- mixture
- weight percent
- silica particles
- insects
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01K—ANIMAL HUSBANDRY; CARE OF BIRDS, FISHES, INSECTS; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
- A01K27/00—Leads or collars, e.g. for dogs
- A01K27/007—Leads or collars, e.g. for dogs with insecticide-dispensing means
Abstract
Abstract of the Disclosure An improved insect-combatting device (e.g., for use against houseflies, gnats and mosquitoes) is disclosed.
The device comprises a shaped solid body having a porous surface capable of gradually and continually releasing naled insecticide in an amount sufficient to provide an insecticidally active concentration of said naled over a prolonged period of time and comprises a synthetic resinous matrix material, from about 15 to about 35 weight percent of naled and a minor amount effective to retard spewing of the insecticide of finely divided silica particles and at least one C14 to C20 saturated aliphatic carboxylic acid or a salt or ester thereof. The device is formed from a mixture of the said synthetic resin, naled, finely divided si1ica particles, C14 to C20 to aliphatic saturated carboxylic acid or salt or ester thereof and a surface porosity control component that is non-reactive in the mixture and has a boiling point at or below the curing temperature to produce surface openings in communication with pores in said body by vaporization of said porosity control component to provide the release of naled gas at a rate effective to control insects in the vicinity of said body, but insufficient to form as spew on the body.
The device comprises a shaped solid body having a porous surface capable of gradually and continually releasing naled insecticide in an amount sufficient to provide an insecticidally active concentration of said naled over a prolonged period of time and comprises a synthetic resinous matrix material, from about 15 to about 35 weight percent of naled and a minor amount effective to retard spewing of the insecticide of finely divided silica particles and at least one C14 to C20 saturated aliphatic carboxylic acid or a salt or ester thereof. The device is formed from a mixture of the said synthetic resin, naled, finely divided si1ica particles, C14 to C20 to aliphatic saturated carboxylic acid or salt or ester thereof and a surface porosity control component that is non-reactive in the mixture and has a boiling point at or below the curing temperature to produce surface openings in communication with pores in said body by vaporization of said porosity control component to provide the release of naled gas at a rate effective to control insects in the vicinity of said body, but insufficient to form as spew on the body.
Description
lOS67Z~
Background of the Invention This invention relates to the control of insects such as common houseflies (Musca domestica), fruit flies (Drosophila melanogaster), mosquitos ~ x pipiens) and other similar insects in the vicinity of an insecticide-containing device.
Heretofore, insect-combatting devices, such as pest strips and the like, comprised of a PVC resin having a dispersion of the insecticide dimethyl
Background of the Invention This invention relates to the control of insects such as common houseflies (Musca domestica), fruit flies (Drosophila melanogaster), mosquitos ~ x pipiens) and other similar insects in the vicinity of an insecticide-containing device.
Heretofore, insect-combatting devices, such as pest strips and the like, comprised of a PVC resin having a dispersion of the insecticide dimethyl
2,2-di-chlorovinyl phosphate, commonly known as DDVP or by its trademark Vapona, have been widely used for the purpose of controlling f]ying insects such as houseflies, mosquitoes and the like in the vicinity of the device.
However, DDVP has been reported to have an objectionable depressing effect on the plasma and red cell cholinesterase at least in animals which effect is particularly acute at high concentrations which are produced during the first few days after a pest strip has first been exposed to the atmosphere. This is believed due to the fact that the liberation rate of DDVP from presently available DDVP-containing pest strips is not uniform but rather is higher during the first few days after activation, i.e., removal of the pest strip from the packing and exposing it to the atmosphere. There are also indications that DDVP may-be harmful to humans. Pest strips containing DDVP have been banned in Nolland. Moreover, the aforementioned initial high liberation rate represents an unduly rapid loss of insecticide and creates an upper limit on the period that DDVP is liberated at a rate sufficient to effectively control pests. DDVP also has been found to possess a high degree of residual toxicity in the area of the device, apparently from adsorption of the DDVP vapors in walls, floors, ceilings, curtains, rugs, and the like. Even after a DDVP-containing pest strip is removed from a room environment, residual DDVP vapors can often be detected for several days thereafter.
It has also been suggested to utilize other insecticides such as naled (1,2-dibromo-2,2-dichloroethyl dimethyl phosphate) in an insect-combatting device such as a pest strip. The prepara-tion of naled is described in United States patent No. 2,971,882 to Osmonson et al. PVC resin-naled combinations have been proposed for use as an insecticide of a general nature in French patent No.
1,568,198, issued April 14, 1969, and in United States patent application Serial No. 85,445, filed January 30, 1961 ~abandoned, but accessible to the public), and corresponding British patent No.
955,350. Netherlands published application No. 6,610,279 dis-closes fly strips composed of PVC-naled as uell as WC-DDVP com-binations which are stated to have such high insecticide release rates as to require an outer laminate layer to retard the insecticide release. United States patent No. 3,344,021 discloses PVC-naled combinations for use as an anthelmintic composition.
A number of problems have been encountered in providing a commercially satisfactory PVC resin-naled combination for use in an insect-combatting device. First, there must be a sufficient amount of naled released to provide effective control of the insects in the vicinity of the device. Contrary to statements in the prior art disclosures, it has been found that release rates for naled are very much less than the release rates for DDVP. Naled has a low vapor pressure of about 2 x 10 4 mm. Hg. at 20C. as compared to that for DDVP of 1.2 x 10 2 to be thus only about 1.7% of the vapor pressure of DDVP.
It has further been found that the inclusion of an insecticide such as naled in a synthetic resin matrix in amounts sufficient to control insects for a commerically acceptable time leads to exudation of liquid insecticide (or "spew") on the surface of the device. These liquid droplets pose serious environmental 1(~567Z4 and aesthetic problems as well as significantly decreasing ~he effective life of the device.
A further unexpected problem found with a PVC-naled composition was the tendency of the resin to decQmpose during the shaping process. For example, unsatisfactory results were obtained in early tests where naled was substituted for DDVP in PVC combinations employed in extrusion apparatus used for making PVC-DDVP pet collars known in the art. Burning and charring of the extrudate were found to occur during curing of the collars, and the finished collar underwent an unexplainable reduction in the naled concentration as compared with the naled concentration in the original mixture.
Summary of the Invention According to this invention there is provided an insect-combatting device and method of using said device which alleviates or avoids the problems of the prior art.
This invention also provides an insect-combatting device which may contain a relatively high loading of insecticide without objectionable liquid insecticide droplet formation on the surface of the device and a method of using such device.
According to a further feature of this invention there is provided an insect-combatting device which is capable of combatting insects in the vicinity of the device by prolonged release of insecticide while minimizing undesired adsorption of the insecticide into contiguous solid objects and a method of using said device.
According to yet another feature of the invention there is provided a method of combatting insects by making a body of synthetic resin containing between about 15% and 35% of naled through the use of a volatile additive lOS67Z4 which is released during the curing step to produce a texture including porous surface openings which allow for an unexpectedly large increase in the release of naled gas at a rate effective to control insects to thus provide a naled-containing device which has a commercially practical effect-ive life.
In one aspect, the present invention provides a device for combat-ting insects comprising a shaped solid body having a porous surface capable of gradually and continually releasing naled insecticide in an amount suffi-cient to provide an insecticidally active concentration of said naled over a prolonged period of time, said device comprising a synthetic resinous matrix material, from about 15 to about 35 weight percent of naled and a minor amount effective to retard spewing of the insecticide of finely divided silica and at least one C14 to C20 saturated aliphatic carboxylic acid or a salt or ester thereof, said device being formed from a mixture of said syn-thetic resin, naled, finely divided silica particles, C14 to C20 aliphatic saturated carboxylic acid or salt or ester thereof and a surface porosity control component that is non-reactive in the mixture and has a boiling point at or below the curing temperature to produce surface openings in communication with pores in said body by vaporization of said porosity control component to provide for release of naled gas at a rate effective to control insects in the vicinity of said body, but insufficient to form a spew on the body.
In another aspect, the present invention provides a device for combatting insects, said device comprising: a discrete body of flexible synthetic resin material conta;n;ng between about 20 and 30 weight percent naled and a spew oS6~z~
retarding amount of from about 15 to about 25 weight percent of finely divided silica particles and from about 0.5 to , about 1.5 weight percent of at least one Cl4 to C20 saturated aliphatic carboxylic acid or a salt or ester thereof; said discrete body being formed from a mixture of said synthetic resin, naled, finely divided silica particles and from about 1 to about 3 weight percent of a surface porosity control component that is non-reactive in the mixture and has a boil-ing point at or below the curing temperature of said resin, said mixture being heated to its curing temperature to pro-duce surface openings in communication with pores in said body by vaporization of said porosity control components to provide for rel~ase of naled gas at a rate effective to con-trol inse~ts in the vicinity of said body, but insufficient to form as droplets on the body.
In still another aspect of the present invention, there is provided a method of controlling insects which comprises:
providing a discrete body comprising a mixture of a synthetic resin, from between about 15 to 35~ by weight of said strip of'naled and a spew retarding amount of finely divided silica particles and at least one Cl4 to C20 satur-ated aliphatic carboxylic acid or a salt or ester thereof;
said body being formed from a mixture of said synthetic resin, naled, silica particles, saturated aliphatic carboxy-lic acid and a minor amount of a surface porosity control agent that is non-reactive in the mixture and has a boiling point at or below the curing temperature of said mixture, which mixture is formed into said body at the curing temper-ature to vaporize said control agent and produce surface porosity in said body to provide for release of naled at a rate to eff`ectively control insects in the vicinity of said ~ -6-~.0567Z~
body but insufficient to form as droplets on the body; and placing and maintaining said body in an area in which said insects are to be controlled.
-6a-Brief Description of the Drawing The FIGURE is a schematic representation of a pre-ferred embodiment of the insect-combatting device of the present invention.
Des _iption of the Preferred Embodiments Referring now the drawings, Fig. 1 shows a typical device adapted for combatting insects. As shown therein, such a device can be in the form of a shaped body 1 having a regular, symmetrical matrix of cavities generally indica-ted as 2 which exte~d throughout one dimension of the body.
The cavities have substantially parallel axes and walls 3 that define an essentially straight line along one dimen-sion. In this fashion, the shaped device has good dimensional stability and ease of manufacture as well as a relatively high surface area from which the insecticide is released.
It will be understood to those skilled in the art that other shapes may also be utilized.
The components making up a satisfactory insectide containing insect-combatting device include a synthetic resin that is compatible with the relatively high amounts of insecticide and a strength sufficient to maintain the inte-grity of the shaped device throughout the period during which the insecticide is released in amounts effective to combat insects, e.g., flies or mosquitoes. The shaped insect-combatting device includes the synthetic resin in a concentra-tion sufficiently Iarge to give the device physical properties such as strength, flexiblity, and freedom from tackiness so as to make it suitable for use as an insect-combattlng device.
Generally, the shaped device contains from about 20 to about 80, preferably from about 25 to about 50, weight percent of the synthetic resin.
~ _7_ lOS672~
The various known synthetic resins which can be used ln the insect-combatting device lnclude materials such as polyethylene, -7a-~ 0567Z4 polypropylene, copolymers of ethylene and propylene, nylon, cellophane, po].yacrylates, such as poly~.ers and copolymers of methylacrylate, ethylacrylate, methylmethacrylate and ethylmethacrylate; polymers of vinyl compounds, such as polystyrene, polymerized divinylbenzene;
polyvinyl halogenides, such as polyvinylchloride; polyvinyacetals, such as polyvinylbutyral; polyvinylidene compounds, such as poly-vinylidenechloride; polyvinylacetate; ethylvinylacetate-vinylacetate copolymers; copolymers of vinylchlorde and vinylacetate; poly-urethanes, polyaldehydes; and ethermoplastics.
Polyvinylchloride (PVC) homopoly~ers and copolymers with other polymers such as polyvinyl acetate (PVA) are preferred synthetic resin materials. Suitable PVC resins are commercially available and include, for example, PVC homopolymer dispersion resin Diamond PVC-7502TM and PVC homopolymer extender resin Diamond PVC-7-446TM, both available from The Diamond Shamrock Co., and mixtures thereof. Other suitable, commercially available PVC resins are kno~in in the art. Suitable PVC-PVA copolymers are also commercially availabl~ and include, for example, Geon 135 (Goodrich Corp.), PVC-74 (Diamond Alkali Co.) and XR-6338 (Exxon-Firestone).
Other PVC-PVA copolymers are also known in the art.
The improved insect-combattir.g device of the present invention contains naled (1,2-dibromo-2,2-dichloroethyl dimethyl phosphate) insecticide in an amount sufficient to provide an insecticidally active concentration of the insectioide over a prolonged period of time (e.g., about 120 days or longer), which amount can be from about 15 to about 35, preferably from about 20 to about 30, weight percent ir.secticide. With insectici~e concentrations in these ranges, the insect-combatting device releases from aboutl.5 to about 5 milligrams of insecticide pex inch of surrace area per day. Alt~ough the insect-combatting device of the present invention may be utilized in any environment 1~567Z4 containing the insects, maximum efficiency may be obtained when the device is utilized in a confined space including these insects.
Generally, the utilization of naled insecticide in amounts of from about 15 to about 35 weight percent in a synthetic resin matrix leads to liquid naled droplet or "spew" f4rmation on the surface of the insect-combatting device. Liquid droplets of naled insecticide forming on the surface of the shaped device pose a substantial health and safety hazzrd as well as diminished insecticidal efficiency. The insect-combatting device of the present invention includes a minor amount effective to retar~
spewing of the insecticide of finely divided silica particles and at least one C14 to C20 saturated aliphatic carboxylic acid or a salt or ester thereof and exhibits a substantially lessened tendency towards formation of liquid droplets of naled insecticide on its surfaces.
Although silica is ~nown in the art, a~or~ with a number of other minerals and glasses, as a filler for various synthetic resins, it has unexpectedly been found that finely divided silica particles generally having 2 particle size of from about 1 to about 50, preferably from about 2 to about 10, microns, exhibit à high degree of re~ative efficiency in retarding insectiaide spewing when utilized in sufficient amounts, which spew-retardiny amounts are generally in the range of from about 10 to about 35, preferably from about 15 to about 25, weight percent of the insect-combatting device. It has been found that utilization of finely divided silica particles in an amount of less than about 10 percent by weight is generally ineffective to provide any significant retardation of the insecticide spew while utilization of finely divided silica particles in an amou~t above about 35 percent by weisht does not result in any further reduction in spew formation.
_g_ .
While the addition of the finely di~ided silica particles exhibit a high ~egree of relative efficiency in retarding naled insect-icide spewing, a small amount of the naled insecticide may nonetheless sometimes exude from the insecticide-containiAg device. It has further been found that the inclusion in the device of a minor amount of at least one C14 to C20 saturated aliphatic carboxylic acid or a salt or ester (e.g., magnesium stearate) thereof, is effective to essentially retard any naled insecticide spewing which might otherwise occur. The C14 to C20 saturated aliphatic carboxylic acid, which can be a mixture of such acids, is generally utilized in an amount of from about 0.25 to about 3, preferably from about 0.5 to about 1.5, weight percent in the device. Stearic acid and palmitic acid are preferred.
While East German Patent 91,898 discloses the addition of a C14 to C20 saturated aliphatic carboxylic acid along with a particular mixture of primary and secondary plasticizers to a polyvinyl chloride-DDVP mixture, the acid-plasticizers mixture being added to retard spewing of the DDVP, it has been found that the utilization of the C14 to C20 saturated aliphatic carboxylic acid alone (i.e., without the finely divided silica particles) with the resin and insecticide in the insect-combat.ing device of the prese~t invention is insufficient to erfectively retard spewing of the naled insecticide from-the device. Similarly, the use G.~ the finely divided silica particles alone (i.e., without the C14 to C20 saturated aliphatic carboxylic acid) is insufficient to effectively retard spewing of the insecticide from the device.
~owever, the utilization of a minor amount of both the finely divided silica particles and the C14 to C20 saturated aliphatic carboxylic acid has been found to possess a hish efficiency for insecticide spew retardation and to effectively maintain the surface of the device free of liquid droplets of the insecticide.
1~)567Z4 It has been ascertained that when the release rate falls o~f to about 0.4 to about 0.6 milligrams of naled per square inch o~ surface area per day, that the effectiveness of the device for insect control has been reduced to the point where it should be replaced. Uti~ization of naled in the device in amounts less than about 20 weight percent results in the release rate reaching an ineffective level in an unsatisfactorily short period of time (e.g., about 90 days or less). Utilization of ~aled in a~ounts greater than about 35 weight percent results in spewing and droplet accumulation on the surface of the device.
The preparation of syntheti;c resin-irsectici2e combinations is achieved by conventional methods. Because of the compatibility of the insecticide in the resin dispersions, the compositions may be prepared merely by mechanical mixing of the pesiicides with powdered resin. Dry blends, fluid pastes, or plastisol dispersions, can be made which, as is known, can be molded, extruded, cast, or otherwise formed into the shape of a band or strip. Where the prepolymerized resin exists in liquid form, as in ~he case of such monomers as styrene or meth~l methacrylate, the insecticide'may be incorporated in the liquid before it is polymerized or cured. The term "dispersion n as used herein is intended to include mixtures or a solid with a liquid, a liquid with a liquid and a solid with a solid.
In the embodiments where polyvin~l resins are used, plasticizers and other additives co~monly used for providing ~he flexibility, strength and surface characteristics desired for an insect-combatting device are well known to those skilled in this art, and no further discussion is deered necessary here.
In addition, coloring ar.d odor control agen~s r.ay be employed in the devices of the present invention to enhance consumer acceptance.
As noted above, naled has a low vapor pressure. The naled release rate from a PVC-naled device is comparatively low and may be inadequate for a commer ~ lly acceptable insect-combatting device.
The use of an additive in the mixture can be very helpful in increas-ing the naled release rate and makes possible both effective insect control at lower initial naled concentrations and an insect-combatting device having an increased effective life.
The additive, also referred to as a surface porosity control component, is present in the final plastisol dispersion or mix used in forming the device, and hence must be non-reactive with the other components of the dispersion or mix. The main function of the additive is to provide a surface porosity which preferably includes pores extending part way into the body of the device. The desired surface characteristics are obtained by the vaporization of the additive during the curing period. Hence the additive should comprise one or more compounds having a boiling point at or below the curing temperature of the resin.
Compounds which are suitable as the surface porosity control component ir. PVC resins which are cured at a temperature in the range of between about 260 to 400F. include aldehydes and their lower alkyl acetals containing bromine or chlorine, generally having a boiling point of from about 170 to about 400, preferably from about 185 to about 350 F. The porosity control component may thus include one or more of the following which have approximate boiling point temperature as set forth:
Name B.F. F.
chloroacetaldehyde 185 dichloroacetaldehyde 192 chloral 218 bromoacetaldehyde 176-221 dibromoacetaldehyde 346 bromodichloroacetaldehyde 258 chlorodibromoacetaldehyde 299 bromochloroacetaldehyde 233 2-bromopropanol 229 The surface porosity control~component is included in the synthetic resïn-naled combination in an amount sufficient to produce sufficient surface porosity by its vaporization during curing of the dispersion to effectively increase the release rate of naled gas from the formed device. While the amount of the porosity control component to be used depends on the density of surface openings desired and somewhat on the particular procedure used for curing the resin, it is genera~ly from about 0.~ to 5, preferably from about 1 to 3, weight percent of the dispersion.
The invention is additionally illustrated in connection with the following Examples which arè to be considered as illustrative of the present inventio~. It chould be understood, however, that the invention is not limited to the specific details of the Examples.
~0567Z4 Example I
A mixture (in parts by weight) of 30 p.b.w. polyvinyl chloride homopolymer dispersion resin 16 p.b.w~ di-2,ethylhexyl phthalate (DOP) 2 p.b.w. epoxidized octyl tallate (EPO) 1 p~b.w. bentone 27 p.b.w. naled (1,2-dibromo-2,dichloroethyl dimethyl phosphate)
However, DDVP has been reported to have an objectionable depressing effect on the plasma and red cell cholinesterase at least in animals which effect is particularly acute at high concentrations which are produced during the first few days after a pest strip has first been exposed to the atmosphere. This is believed due to the fact that the liberation rate of DDVP from presently available DDVP-containing pest strips is not uniform but rather is higher during the first few days after activation, i.e., removal of the pest strip from the packing and exposing it to the atmosphere. There are also indications that DDVP may-be harmful to humans. Pest strips containing DDVP have been banned in Nolland. Moreover, the aforementioned initial high liberation rate represents an unduly rapid loss of insecticide and creates an upper limit on the period that DDVP is liberated at a rate sufficient to effectively control pests. DDVP also has been found to possess a high degree of residual toxicity in the area of the device, apparently from adsorption of the DDVP vapors in walls, floors, ceilings, curtains, rugs, and the like. Even after a DDVP-containing pest strip is removed from a room environment, residual DDVP vapors can often be detected for several days thereafter.
It has also been suggested to utilize other insecticides such as naled (1,2-dibromo-2,2-dichloroethyl dimethyl phosphate) in an insect-combatting device such as a pest strip. The prepara-tion of naled is described in United States patent No. 2,971,882 to Osmonson et al. PVC resin-naled combinations have been proposed for use as an insecticide of a general nature in French patent No.
1,568,198, issued April 14, 1969, and in United States patent application Serial No. 85,445, filed January 30, 1961 ~abandoned, but accessible to the public), and corresponding British patent No.
955,350. Netherlands published application No. 6,610,279 dis-closes fly strips composed of PVC-naled as uell as WC-DDVP com-binations which are stated to have such high insecticide release rates as to require an outer laminate layer to retard the insecticide release. United States patent No. 3,344,021 discloses PVC-naled combinations for use as an anthelmintic composition.
A number of problems have been encountered in providing a commercially satisfactory PVC resin-naled combination for use in an insect-combatting device. First, there must be a sufficient amount of naled released to provide effective control of the insects in the vicinity of the device. Contrary to statements in the prior art disclosures, it has been found that release rates for naled are very much less than the release rates for DDVP. Naled has a low vapor pressure of about 2 x 10 4 mm. Hg. at 20C. as compared to that for DDVP of 1.2 x 10 2 to be thus only about 1.7% of the vapor pressure of DDVP.
It has further been found that the inclusion of an insecticide such as naled in a synthetic resin matrix in amounts sufficient to control insects for a commerically acceptable time leads to exudation of liquid insecticide (or "spew") on the surface of the device. These liquid droplets pose serious environmental 1(~567Z4 and aesthetic problems as well as significantly decreasing ~he effective life of the device.
A further unexpected problem found with a PVC-naled composition was the tendency of the resin to decQmpose during the shaping process. For example, unsatisfactory results were obtained in early tests where naled was substituted for DDVP in PVC combinations employed in extrusion apparatus used for making PVC-DDVP pet collars known in the art. Burning and charring of the extrudate were found to occur during curing of the collars, and the finished collar underwent an unexplainable reduction in the naled concentration as compared with the naled concentration in the original mixture.
Summary of the Invention According to this invention there is provided an insect-combatting device and method of using said device which alleviates or avoids the problems of the prior art.
This invention also provides an insect-combatting device which may contain a relatively high loading of insecticide without objectionable liquid insecticide droplet formation on the surface of the device and a method of using such device.
According to a further feature of this invention there is provided an insect-combatting device which is capable of combatting insects in the vicinity of the device by prolonged release of insecticide while minimizing undesired adsorption of the insecticide into contiguous solid objects and a method of using said device.
According to yet another feature of the invention there is provided a method of combatting insects by making a body of synthetic resin containing between about 15% and 35% of naled through the use of a volatile additive lOS67Z4 which is released during the curing step to produce a texture including porous surface openings which allow for an unexpectedly large increase in the release of naled gas at a rate effective to control insects to thus provide a naled-containing device which has a commercially practical effect-ive life.
In one aspect, the present invention provides a device for combat-ting insects comprising a shaped solid body having a porous surface capable of gradually and continually releasing naled insecticide in an amount suffi-cient to provide an insecticidally active concentration of said naled over a prolonged period of time, said device comprising a synthetic resinous matrix material, from about 15 to about 35 weight percent of naled and a minor amount effective to retard spewing of the insecticide of finely divided silica and at least one C14 to C20 saturated aliphatic carboxylic acid or a salt or ester thereof, said device being formed from a mixture of said syn-thetic resin, naled, finely divided silica particles, C14 to C20 aliphatic saturated carboxylic acid or salt or ester thereof and a surface porosity control component that is non-reactive in the mixture and has a boiling point at or below the curing temperature to produce surface openings in communication with pores in said body by vaporization of said porosity control component to provide for release of naled gas at a rate effective to control insects in the vicinity of said body, but insufficient to form a spew on the body.
In another aspect, the present invention provides a device for combatting insects, said device comprising: a discrete body of flexible synthetic resin material conta;n;ng between about 20 and 30 weight percent naled and a spew oS6~z~
retarding amount of from about 15 to about 25 weight percent of finely divided silica particles and from about 0.5 to , about 1.5 weight percent of at least one Cl4 to C20 saturated aliphatic carboxylic acid or a salt or ester thereof; said discrete body being formed from a mixture of said synthetic resin, naled, finely divided silica particles and from about 1 to about 3 weight percent of a surface porosity control component that is non-reactive in the mixture and has a boil-ing point at or below the curing temperature of said resin, said mixture being heated to its curing temperature to pro-duce surface openings in communication with pores in said body by vaporization of said porosity control components to provide for rel~ase of naled gas at a rate effective to con-trol inse~ts in the vicinity of said body, but insufficient to form as droplets on the body.
In still another aspect of the present invention, there is provided a method of controlling insects which comprises:
providing a discrete body comprising a mixture of a synthetic resin, from between about 15 to 35~ by weight of said strip of'naled and a spew retarding amount of finely divided silica particles and at least one Cl4 to C20 satur-ated aliphatic carboxylic acid or a salt or ester thereof;
said body being formed from a mixture of said synthetic resin, naled, silica particles, saturated aliphatic carboxy-lic acid and a minor amount of a surface porosity control agent that is non-reactive in the mixture and has a boiling point at or below the curing temperature of said mixture, which mixture is formed into said body at the curing temper-ature to vaporize said control agent and produce surface porosity in said body to provide for release of naled at a rate to eff`ectively control insects in the vicinity of said ~ -6-~.0567Z~
body but insufficient to form as droplets on the body; and placing and maintaining said body in an area in which said insects are to be controlled.
-6a-Brief Description of the Drawing The FIGURE is a schematic representation of a pre-ferred embodiment of the insect-combatting device of the present invention.
Des _iption of the Preferred Embodiments Referring now the drawings, Fig. 1 shows a typical device adapted for combatting insects. As shown therein, such a device can be in the form of a shaped body 1 having a regular, symmetrical matrix of cavities generally indica-ted as 2 which exte~d throughout one dimension of the body.
The cavities have substantially parallel axes and walls 3 that define an essentially straight line along one dimen-sion. In this fashion, the shaped device has good dimensional stability and ease of manufacture as well as a relatively high surface area from which the insecticide is released.
It will be understood to those skilled in the art that other shapes may also be utilized.
The components making up a satisfactory insectide containing insect-combatting device include a synthetic resin that is compatible with the relatively high amounts of insecticide and a strength sufficient to maintain the inte-grity of the shaped device throughout the period during which the insecticide is released in amounts effective to combat insects, e.g., flies or mosquitoes. The shaped insect-combatting device includes the synthetic resin in a concentra-tion sufficiently Iarge to give the device physical properties such as strength, flexiblity, and freedom from tackiness so as to make it suitable for use as an insect-combattlng device.
Generally, the shaped device contains from about 20 to about 80, preferably from about 25 to about 50, weight percent of the synthetic resin.
~ _7_ lOS672~
The various known synthetic resins which can be used ln the insect-combatting device lnclude materials such as polyethylene, -7a-~ 0567Z4 polypropylene, copolymers of ethylene and propylene, nylon, cellophane, po].yacrylates, such as poly~.ers and copolymers of methylacrylate, ethylacrylate, methylmethacrylate and ethylmethacrylate; polymers of vinyl compounds, such as polystyrene, polymerized divinylbenzene;
polyvinyl halogenides, such as polyvinylchloride; polyvinyacetals, such as polyvinylbutyral; polyvinylidene compounds, such as poly-vinylidenechloride; polyvinylacetate; ethylvinylacetate-vinylacetate copolymers; copolymers of vinylchlorde and vinylacetate; poly-urethanes, polyaldehydes; and ethermoplastics.
Polyvinylchloride (PVC) homopoly~ers and copolymers with other polymers such as polyvinyl acetate (PVA) are preferred synthetic resin materials. Suitable PVC resins are commercially available and include, for example, PVC homopolymer dispersion resin Diamond PVC-7502TM and PVC homopolymer extender resin Diamond PVC-7-446TM, both available from The Diamond Shamrock Co., and mixtures thereof. Other suitable, commercially available PVC resins are kno~in in the art. Suitable PVC-PVA copolymers are also commercially availabl~ and include, for example, Geon 135 (Goodrich Corp.), PVC-74 (Diamond Alkali Co.) and XR-6338 (Exxon-Firestone).
Other PVC-PVA copolymers are also known in the art.
The improved insect-combattir.g device of the present invention contains naled (1,2-dibromo-2,2-dichloroethyl dimethyl phosphate) insecticide in an amount sufficient to provide an insecticidally active concentration of the insectioide over a prolonged period of time (e.g., about 120 days or longer), which amount can be from about 15 to about 35, preferably from about 20 to about 30, weight percent ir.secticide. With insectici~e concentrations in these ranges, the insect-combatting device releases from aboutl.5 to about 5 milligrams of insecticide pex inch of surrace area per day. Alt~ough the insect-combatting device of the present invention may be utilized in any environment 1~567Z4 containing the insects, maximum efficiency may be obtained when the device is utilized in a confined space including these insects.
Generally, the utilization of naled insecticide in amounts of from about 15 to about 35 weight percent in a synthetic resin matrix leads to liquid naled droplet or "spew" f4rmation on the surface of the insect-combatting device. Liquid droplets of naled insecticide forming on the surface of the shaped device pose a substantial health and safety hazzrd as well as diminished insecticidal efficiency. The insect-combatting device of the present invention includes a minor amount effective to retar~
spewing of the insecticide of finely divided silica particles and at least one C14 to C20 saturated aliphatic carboxylic acid or a salt or ester thereof and exhibits a substantially lessened tendency towards formation of liquid droplets of naled insecticide on its surfaces.
Although silica is ~nown in the art, a~or~ with a number of other minerals and glasses, as a filler for various synthetic resins, it has unexpectedly been found that finely divided silica particles generally having 2 particle size of from about 1 to about 50, preferably from about 2 to about 10, microns, exhibit à high degree of re~ative efficiency in retarding insectiaide spewing when utilized in sufficient amounts, which spew-retardiny amounts are generally in the range of from about 10 to about 35, preferably from about 15 to about 25, weight percent of the insect-combatting device. It has been found that utilization of finely divided silica particles in an amount of less than about 10 percent by weight is generally ineffective to provide any significant retardation of the insecticide spew while utilization of finely divided silica particles in an amou~t above about 35 percent by weisht does not result in any further reduction in spew formation.
_g_ .
While the addition of the finely di~ided silica particles exhibit a high ~egree of relative efficiency in retarding naled insect-icide spewing, a small amount of the naled insecticide may nonetheless sometimes exude from the insecticide-containiAg device. It has further been found that the inclusion in the device of a minor amount of at least one C14 to C20 saturated aliphatic carboxylic acid or a salt or ester (e.g., magnesium stearate) thereof, is effective to essentially retard any naled insecticide spewing which might otherwise occur. The C14 to C20 saturated aliphatic carboxylic acid, which can be a mixture of such acids, is generally utilized in an amount of from about 0.25 to about 3, preferably from about 0.5 to about 1.5, weight percent in the device. Stearic acid and palmitic acid are preferred.
While East German Patent 91,898 discloses the addition of a C14 to C20 saturated aliphatic carboxylic acid along with a particular mixture of primary and secondary plasticizers to a polyvinyl chloride-DDVP mixture, the acid-plasticizers mixture being added to retard spewing of the DDVP, it has been found that the utilization of the C14 to C20 saturated aliphatic carboxylic acid alone (i.e., without the finely divided silica particles) with the resin and insecticide in the insect-combat.ing device of the prese~t invention is insufficient to erfectively retard spewing of the naled insecticide from-the device. Similarly, the use G.~ the finely divided silica particles alone (i.e., without the C14 to C20 saturated aliphatic carboxylic acid) is insufficient to effectively retard spewing of the insecticide from the device.
~owever, the utilization of a minor amount of both the finely divided silica particles and the C14 to C20 saturated aliphatic carboxylic acid has been found to possess a hish efficiency for insecticide spew retardation and to effectively maintain the surface of the device free of liquid droplets of the insecticide.
1~)567Z4 It has been ascertained that when the release rate falls o~f to about 0.4 to about 0.6 milligrams of naled per square inch o~ surface area per day, that the effectiveness of the device for insect control has been reduced to the point where it should be replaced. Uti~ization of naled in the device in amounts less than about 20 weight percent results in the release rate reaching an ineffective level in an unsatisfactorily short period of time (e.g., about 90 days or less). Utilization of ~aled in a~ounts greater than about 35 weight percent results in spewing and droplet accumulation on the surface of the device.
The preparation of syntheti;c resin-irsectici2e combinations is achieved by conventional methods. Because of the compatibility of the insecticide in the resin dispersions, the compositions may be prepared merely by mechanical mixing of the pesiicides with powdered resin. Dry blends, fluid pastes, or plastisol dispersions, can be made which, as is known, can be molded, extruded, cast, or otherwise formed into the shape of a band or strip. Where the prepolymerized resin exists in liquid form, as in ~he case of such monomers as styrene or meth~l methacrylate, the insecticide'may be incorporated in the liquid before it is polymerized or cured. The term "dispersion n as used herein is intended to include mixtures or a solid with a liquid, a liquid with a liquid and a solid with a solid.
In the embodiments where polyvin~l resins are used, plasticizers and other additives co~monly used for providing ~he flexibility, strength and surface characteristics desired for an insect-combatting device are well known to those skilled in this art, and no further discussion is deered necessary here.
In addition, coloring ar.d odor control agen~s r.ay be employed in the devices of the present invention to enhance consumer acceptance.
As noted above, naled has a low vapor pressure. The naled release rate from a PVC-naled device is comparatively low and may be inadequate for a commer ~ lly acceptable insect-combatting device.
The use of an additive in the mixture can be very helpful in increas-ing the naled release rate and makes possible both effective insect control at lower initial naled concentrations and an insect-combatting device having an increased effective life.
The additive, also referred to as a surface porosity control component, is present in the final plastisol dispersion or mix used in forming the device, and hence must be non-reactive with the other components of the dispersion or mix. The main function of the additive is to provide a surface porosity which preferably includes pores extending part way into the body of the device. The desired surface characteristics are obtained by the vaporization of the additive during the curing period. Hence the additive should comprise one or more compounds having a boiling point at or below the curing temperature of the resin.
Compounds which are suitable as the surface porosity control component ir. PVC resins which are cured at a temperature in the range of between about 260 to 400F. include aldehydes and their lower alkyl acetals containing bromine or chlorine, generally having a boiling point of from about 170 to about 400, preferably from about 185 to about 350 F. The porosity control component may thus include one or more of the following which have approximate boiling point temperature as set forth:
Name B.F. F.
chloroacetaldehyde 185 dichloroacetaldehyde 192 chloral 218 bromoacetaldehyde 176-221 dibromoacetaldehyde 346 bromodichloroacetaldehyde 258 chlorodibromoacetaldehyde 299 bromochloroacetaldehyde 233 2-bromopropanol 229 The surface porosity control~component is included in the synthetic resïn-naled combination in an amount sufficient to produce sufficient surface porosity by its vaporization during curing of the dispersion to effectively increase the release rate of naled gas from the formed device. While the amount of the porosity control component to be used depends on the density of surface openings desired and somewhat on the particular procedure used for curing the resin, it is genera~ly from about 0.~ to 5, preferably from about 1 to 3, weight percent of the dispersion.
The invention is additionally illustrated in connection with the following Examples which arè to be considered as illustrative of the present inventio~. It chould be understood, however, that the invention is not limited to the specific details of the Examples.
~0567Z4 Example I
A mixture (in parts by weight) of 30 p.b.w. polyvinyl chloride homopolymer dispersion resin 16 p.b.w~ di-2,ethylhexyl phthalate (DOP) 2 p.b.w. epoxidized octyl tallate (EPO) 1 p~b.w. bentone 27 p.b.w. naled (1,2-dibromo-2,dichloroethyl dimethyl phosphate)
3 p.b.w. bromodichloroacetaldehyde 20 p.b.w. amorphous silica particles, average part cle size, 2.35 microns 1 p.b.w. palmitic acid is thoroughly triturated to form a plastisol dispersion having a viscosity at 25~C. of 16,000 cps. as measured on a Brookfield viscometer at 20 rpm., 12,000 at 2 rpm. A portion of the plastisol is metered to a closed machined aluminum cast mold having a honeycomb-shaped cavity as in the Figure. Temperature of the mold at filling time, as indicated by a thermocouple immediately beneath the cavity surface is 390F. The mold temperature is maintained at 390F. for 2.5 minutes to maintain the dispersion at or above the curing temperature, after which the mold temperature is lowered rapidly to ambient temperature. The color of the device is brownish bronze. A strong medicinal odor emanating from the finished resin is detected.
Analysis of the device after curing and cooling shows the naled content of the collar to be 26~ by weight.
The polyvinyl chloride dispersion used is commercially available from the Diamond Shamrock Company (PVC 7502) and ~s a high molecular ~eight homopol~mer dispersion resin having particle size less than two microns; specific viscosity is 1.62 to 1.68 as measured in 1~ solution of the resin in cyclohexane at 30C.
according to ASTM procedure.
DOP is a plasticizer for PVC and EPO is a stabilizer. The bentone is added to control the viscosity of the plastisol.
The akove dispersion and extender resins are as easy to work with in producing 2 satisfactory de~ice as any that have been used. However, as those sXilled in this art well know, a large number of other materials, as discussed above, can be used.
Naled is not known to react chemically with any synthetic resin, and considerable variations in both.ingredients and proportions can be successfully used.
Example II
The quantities and procedures of Example l are repeated except that an open-faced mold is utilized. The top s de of the device is rounded due to the menisc~s formed on filling the mold, the shape being-retained during curing. The resulting device is brownish bronze and contains 25% naled. Apparently a small portion of the naled was lost by vaporization or by being carried off by vapori~ation of the sur~ace porosity control component during curing. The same medicinal odor was:present.
Example III
The procedure of Example I is repeated using a plastisol dispersion consisting in parts by weight of:
PVC homo olymer dispersion resin PVC homopolymer extender resin 18 di-2-ethylhexylphthalate (DOP) 2 epoxidized cotyl tallate 22 naled (1,2-dibxomo-2,2-dichloroethyl dimethyl phosphate) 2 surface porosity control component (e.g., bromodichloroacetaldehyde) amorphous silica particles, average particle size -microns 1 stearic acid A bronze colored resin body suitable as a pest strip is obtained which analyzed 22% by weight of naled after curing and cooling. A
medicinal odor was present.
Example IV
Following the procedure of Example I and using a plastisol dispersion consisting in parts by weight of PVC homopolymer dispersion resin 11 PVC homopolymer extender resin 9 di-2-ethylhexylphthalate (DOP) 2.5 epoxized octyl tallate 1 bentone 28 naled (1,2-dibromo 2,2-dichloroethyl dimethyl phosphate 2 surface porosity control component (e.g., bromodichloroacetaldehyde) a~orphous silica particles, average particle size -microns 1.5 palmitic acid a bronze colored resin body suitable for use as a pest strip is obtained after curins and cooling which analyzed 26 weight percent naled after curing and cooling. A medicinal odor was present.
Example V
The mixture and procedure of Example I is repeated except that 30 weight percent of a technical grade of naled (1,2-dibromo-2,2-dichloroethyl dimethyl phosphate) commercially available from the Chevron Chemical Company is used. This product is known to contain certain impurities such as bromodichloroacetaldehyde, chloral, carbon tetrachloride and various forms of phosphates.
These impurities constitute about 9 weight percent of the product and in large part are sufficiently volatile as to be released during the curing of the collar or shortly thereafter and hence not to interfere with the functioning of the collar.
The device formed and cured in the manner indicated in Example I is brownis~, bronze and contains about 26 weight percent naled.
Example VI
A uniform mixture (in parts by weight) is made of 29.0 p.b.w. polyvinyl chloride homopolymer general purpose resin 15.3 p.b.w. di-2,ethylhexyl phth~late (DO.') 2.0 p.b.w. epoxidized octyl tallate ~EPO) 25.7 p.b.w. naled (1,2-d bromo-2,2-dichloroethyl dimethyl phosphate) 3.0 p.b.w. bromodichloroacetaldehyde 20.0 p.b.w. amorp}.ous silica particles, average particle size 2.35 microns - 1.0 p.b.w. stearic acid
Analysis of the device after curing and cooling shows the naled content of the collar to be 26~ by weight.
The polyvinyl chloride dispersion used is commercially available from the Diamond Shamrock Company (PVC 7502) and ~s a high molecular ~eight homopol~mer dispersion resin having particle size less than two microns; specific viscosity is 1.62 to 1.68 as measured in 1~ solution of the resin in cyclohexane at 30C.
according to ASTM procedure.
DOP is a plasticizer for PVC and EPO is a stabilizer. The bentone is added to control the viscosity of the plastisol.
The akove dispersion and extender resins are as easy to work with in producing 2 satisfactory de~ice as any that have been used. However, as those sXilled in this art well know, a large number of other materials, as discussed above, can be used.
Naled is not known to react chemically with any synthetic resin, and considerable variations in both.ingredients and proportions can be successfully used.
Example II
The quantities and procedures of Example l are repeated except that an open-faced mold is utilized. The top s de of the device is rounded due to the menisc~s formed on filling the mold, the shape being-retained during curing. The resulting device is brownish bronze and contains 25% naled. Apparently a small portion of the naled was lost by vaporization or by being carried off by vapori~ation of the sur~ace porosity control component during curing. The same medicinal odor was:present.
Example III
The procedure of Example I is repeated using a plastisol dispersion consisting in parts by weight of:
PVC homo olymer dispersion resin PVC homopolymer extender resin 18 di-2-ethylhexylphthalate (DOP) 2 epoxidized cotyl tallate 22 naled (1,2-dibxomo-2,2-dichloroethyl dimethyl phosphate) 2 surface porosity control component (e.g., bromodichloroacetaldehyde) amorphous silica particles, average particle size -microns 1 stearic acid A bronze colored resin body suitable as a pest strip is obtained which analyzed 22% by weight of naled after curing and cooling. A
medicinal odor was present.
Example IV
Following the procedure of Example I and using a plastisol dispersion consisting in parts by weight of PVC homopolymer dispersion resin 11 PVC homopolymer extender resin 9 di-2-ethylhexylphthalate (DOP) 2.5 epoxized octyl tallate 1 bentone 28 naled (1,2-dibromo 2,2-dichloroethyl dimethyl phosphate 2 surface porosity control component (e.g., bromodichloroacetaldehyde) a~orphous silica particles, average particle size -microns 1.5 palmitic acid a bronze colored resin body suitable for use as a pest strip is obtained after curins and cooling which analyzed 26 weight percent naled after curing and cooling. A medicinal odor was present.
Example V
The mixture and procedure of Example I is repeated except that 30 weight percent of a technical grade of naled (1,2-dibromo-2,2-dichloroethyl dimethyl phosphate) commercially available from the Chevron Chemical Company is used. This product is known to contain certain impurities such as bromodichloroacetaldehyde, chloral, carbon tetrachloride and various forms of phosphates.
These impurities constitute about 9 weight percent of the product and in large part are sufficiently volatile as to be released during the curing of the collar or shortly thereafter and hence not to interfere with the functioning of the collar.
The device formed and cured in the manner indicated in Example I is brownis~, bronze and contains about 26 weight percent naled.
Example VI
A uniform mixture (in parts by weight) is made of 29.0 p.b.w. polyvinyl chloride homopolymer general purpose resin 15.3 p.b.w. di-2,ethylhexyl phth~late (DO.') 2.0 p.b.w. epoxidized octyl tallate ~EPO) 25.7 p.b.w. naled (1,2-d bromo-2,2-dichloroethyl dimethyl phosphate) 3.0 p.b.w. bromodichloroacetaldehyde 20.0 p.b.w. amorp}.ous silica particles, average particle size 2.35 microns - 1.0 p.b.w. stearic acid
4.0 p.b.w. heat-s~abilizer and lubricant 1~)567Z4 The heat stabilizer and lubricant is a mixture of 3.3 p.b.w.
dibasic lead phosphate and 0.7 p.b.w. dibasic lead stearate.
The mixture is fed to an injection molding machine and injection moldèd into the shape shown in the Figure at a temperature of 2~5F. and a pressure of from 10,000 to 2~,000 psi. The colox of the device is brownish bronze and a strong medicinal oZor emanating from the molded device is detected.
Analysis of the device arter cooling shows the naled content to be about 25% by weight.
Naled Release Rates The release rate of naled from compositions utilizable in this invention for a given surface area of a device of given thickness and surface area varies dependin~ upon not only the initial nale~
concentration, but more importantly on ~;hether or not the volatile additive which serves as a porosity control component has been used as discussed above. A device formed according to the present invention containing a sufficier.t amount for several months to control insects in the area of the device.
One significant advantzge of the naled device of the present invention over the prior art DDVP device in current commercial use is found in the pattern of release of insecticide as a gas during the first few days of activation which starts at the moment of removal from a sealed ccntainer. The initial release rate of naled during the first few days is only a fraction of the initial release rate of DDVP from comparable devices due mainly to tlie difference in vapor pressure. For naled with porosity control additive, the release rate does not decrezse noticably for a period of about 10 weeks; thereafter, the release rate gradually d~creases to about 50~ of the maximum at the end of about 20 weeks. The pattern of the release rate curve for naled from a PVC device without the porosity control co~ponent is 10567;~4 generally parallel. ~owever, the total amour.t of naled released from a device made from a formulation contairlinG the porosity control component is significantly higher (e.g., 10% or more) than that released from a device made from a similar formulation without the porosity control component which indicates tha~ more naled is being released at any given time within that 20 week period for the former device than the latter device.
Comparative ~xample A
Following the procedure of Example II and using a plastisol dispersion consistinS in parts by weight of 20 PVC homopolymer dispersion resin 12 PVC homopol~er extender resin 15 di-2-ethylhexylphthalate 2 epoxidized octyl tallate 30 naled (1,2-dibromo-2,2-dichloroe~hyl dimethyl phosphate) 20 amorphous silica particles, average particle size - microns 1 stearic acid The~cured strip contains about 25~ weight naled indicating that more of the naled initially present in this dispersion was lost during the curing process than that lost in Ex mple II.
Example VII
The procedure and quantity of Example I is repeated. The resulting device having a 1 square inch surface area is designated "A". Similar devices are made accordir.g ~o the procedure and ~uantity of Example I except that 1~ (by weight) stearic acid is utilized in place of the palmitic acid ~device "B"), 2% ~by welght stearic acid .is utilized in place of the palmitic acid (device "C"), the palmitic acid component is omitted (device "D"), the silica co~.ponent is omitted (device "~") and both the silica and palmitic acid components are omitted (device "F").
Each of these devices are suspended in a 20 cubic foot cell having dimensions of 2' x 2' x 5'. The cells consisted of a framework covered on the end and three sides with a kraft-paper-foil laminate, closed on the top with plate glass to facilitate observation.
The strips are suspended from the top in the middle o~ the cell so as not to touch the sides or bottom of the cell. The test was conducted for 16 weeks.
Visual observations of the surfaces of each device are made daily to dertermine the formation of liquid droplets of naled. The observations include the time at which the surface first appears "slick" or "wet" with bead or droplet formation, the first time at which run marks are observed and the time at which drops are actually formed on the bottom of the sample. These results are shown below in Table I.
-`-- 1()56724 ~3 _ _ __ ~ 3 3 ~ ~r _ _ _ u~
u~
~ ~ I
. ~ r~
_ u~ u~
a) 3 3 .,1 C~ O ~D
H r-l ~1 m .
3 3 .
m o ~D
u~
~1 _ .
. ~ 00 ,~
., . .
.Y ~
o,- ~
,~ ~ ~ o .. - a q I ~: R I 1 O C) t 0 ~ rl O U~
01 ~ 1 Q
~n --~ ~ o ~ ~
I ~ ~ R. O
o ~ o Id ~ Q~
1~1 ~ : Q S~ S o O S~ O
4~ ~,1 a) ~ ~ ~
~ ~ o a~ U~ 3 ~ o ~ ~s~
,1 ~> O ::1 Q
E~ h tO ~ ~
105672'~
As may be seen from the Table, the devices which did not contain both the silica component and the C14 to C20 saturated aliphatic car~oxylic acid compor.ent exhibit beading in relatively short times. Botn Device E ~acid but no silica) and Device F
(which contained neither silica nor the acid) show a slick look in about 2 weeks and beading in about 4 weeks while Device D
(silica but no acid) shows beading in about 6 weeks and drop formation in about 10 weeks. A11 of the devices of the present invention (Devices A, B and C) show beading at a considerably later time and no drop formation.
The biological activity of Devices B, C and D is measured against SRS susceptible Musca domestica.
25 of the SRS susceptible houseflies are added each day to each cell containing a device. The LT50 value (in minutes) is measured. As known in the art LT50 is the time for lethal effect on 50% of the insects introduced. Table II shows the values obtained for male SRS Susceptible houseflies. Similar results are obtained also with remale SRS Susceptible houseflies although the latter are generally more resistant.
TABLE II
-LT50 -Minutes SRS Susceptible =
LT50 ~ minutes Age of Device B C D
- Days .
29 __ 57 __ __ 5~ 62 49 68 __ 62 1056~Z4 The values obtained indicate that the addition of the acid component does not affect the biological activity of the devices. Similar results are obtained when the tests are repeated with CS.~ (NAIDM) Susceptible Musca domestica and resistant strains FC, Orlando DDT and Isolan-B Musca domestica.
The latter are pure, resistant strains of Musca domestica as recognized by the s~illed artisan.
Example VIII
Tests of blological activity or houseflies (~usca domestica), both resis~ant and susceptible strains and mosquitos r ~Culex ipiens) are conducted in the cell utilized in Example VI.
The insects are introduced into the cell containing a device made in accordance with Example I and containing 25% by weight naled. Both the LT50 and LT95 are measured. The results are shown below in Table III.
)5~i7Z4 ul In oc~
Q
X -O
~ ~ ~ o ~ ~
. , . U~
a~ u~ x ~1 C~ o CO ~ CO ~ 1--E~ ~ a~ ~ o ~D
~ ~ ~ 7 .~ o . _ ~ O In C~ O ~r o ~0 E~ ~
H ~0 U~ . ~ 1 ~J
. ~ ~ ___ ._ ~: .~ ~n .
E~ ~ U') X~ o~ oo X
. ~ ~ CO ~
S:: _ R
~,~ o X X X ~
a) E~ ~ a~ ~I o a~ ~
1~; ~ ~ r o 3 3 ::~0 . ~._ ~ O
Q.
. Q. ~l :>~- C~,~
` ~S ~ ~ C~ O ~D ~ ~ I~ ~ Lr) O ~
~ ~ XX
10567~4 The results show that. the naled-containing devices emitted the naled insecticide slowly and uniformly over a 20 week period. The devices were effective in killing both resistant and susceptible houseflies as well as the less hardy mosquitoes.
Similar tests conducted with Drosophilia melanogaster show that these insects are also killed faster than houseflies.
Similar devices containing 25 weight percent naled are hung in the hallway of a building for 20 weeks and exposed to ambient temperatures. The percent naled remaining in the devices (average of 5 devices) is shown in Table IV.
Table IV
Exposure Time Wt. ~ Naled Remaining (heeks) in Exposed Devices 0 25.25 1 24.66 2 23.22 4 21.22 8 17.38 12 15.98 16 13.28 12.34 This test further shows that the devices release the naled insecticide uniformly over a prolonged period of time.
Although some beading of the naled insecticide is noticed at a~out 16 weeks exposure, no drops or -un r.;arks are o~served at the end of the 20 wee'~ test.
Example IX
Samples of various household surfaces (aluminum roil, synthetic fiber carpet, particle board, wood, wood-semi-gloss enamel, vinyl wallpaper, wood-gloss enamel, vinyl flooring ar,d lOS6724 tempered hardboard) are placed in a cell as utilized in Example IV and exposed for 102 days to the 25 weight percent naled-containing device of Example 6. The devices are utilized in an amount of one devlce per 20 cubic feet (Run G) and two devices per 20 cubic feet (Run H). Identical sa~ples are exposed for the same time to a commercially available pest strip containing 20% by weight DDVP
(dimethyl 2,2-~i-chlorovinyl phosphate) at a rate of one device per 20 cubic feet (Run I). The adsorption of the naled or DDVP
toxicant was ~etermined by biological activity of the exposed material placed in a sealed one gallon tank in which houseflies are introduced. The LT50 values for each is measured and the time in days for each to reach an LT,G of 300 minutes by ventilation of the tank is estimated. The results are shown below in Table V.
Table V
_ Estimated Days Venti-~T50 ~ ~lir,utes lation To Reach LT50 . .. . _ . ..... _ _ G H I G H
._ _ ... __ _ . __ . . . .. . __ , Aluminum Foil No Effect ~o Effect No Effect _ _ _ Carpet-Synthetic Fiber 185 125 40 C5~ 1 CS~ 1 13 Particle Board - Vinyl 135 86 37 6 12 16 Wood 104 76 38 5 15 20 Wood Semi-Gloss Enamel 125 109 50 9 12 28 Wall paper - Vinyl 110 78 34 11 13 36 ~'ood - Gloss Enamel 125 79 40 24 30 40 Vinyl Flooring 128 98 35 9 13 42 Tempered Hardboard 135 102 50 7 15 46 ~0567Z4 The results show that considerably less naled is adsorbed on the surfaces than DDVP (as evidence by the much longer LT O times for naled). With ventilation, the naled was desorbed much faster than the DDVP. Similar tests are performed with various foods (potato, apple, bread, lettuce tomato , orange and hamburger) with 24 hour exposure.
DDVP adsorption (as compared with naledj was even higher.
DDVP is adsorbed on all foods tests with LT50 values rang-ing from 12 minutes (potato) to 51 minutes (hamburger).
Naled at the same concentration is not adsorbed on a number of the food tested and when adsorbed, exhibits LT50 values ranging from 155 minutes (potato) to 380 minutes (sliced apple).
C~mparative Example B
An investigation is lmdertaken to determine the effects of v`arious materials on the release rates and efficacy of polyvinyl chloride formulations containing about 25 weight percent naled, about 3 weight percent of a poro-sity control component and minor amounts of PVC plasticizers and stabilizers.
On the basis of an initial screening, calcium carbonate (average aluminum oxide and various silicone fluids and resins are found to unsuitable either because of their reac-tivity with naled or the porosity control component or be-cause of strong incompatibility with the PVC formulations, even at relatively low loading levels of about 5 to 15 weight percent in the formulation. Several grades of pow-dered polyethylene and ethylene-vinyl acetate resins are also tested and determined unsuitable due to their extremely high plasticizer absorption as well as their cost.
105~i7Z4 Several grades of solid glass microspheres (average particle sizes ranging from about 6 to 50 microns) are also tested. All grades of solid glass microspheres exhibit relatively bad settling proklems (greater with increasing particle size).
In addition, devices made in accordance with Example I containing 25 weight percert naled and 45 weight percent of the solid glass microspheres eY.hibit a surface slickness ~or sweating) after only 2 to 3 weeks. Similar samples made including 45 weight percent silica particles (in one instance, all particles through a 325 mesh sieve 95~ of the particles less than 40 microns and in another instance, all through a 200 mesh sieve, 95~ less than 75 microns) exhi~it sweating in 5 to 6 weeks.
Summary of Advantages The insect-combatting device of the present invention contains relatively high amounts of naled which are uniformly released over a prolonged period of time. ~laled has a reduced toxicity as compared to the prior art DDVP-containing devices and shows a substantially lower tendency towards adsorption on surfaces near the aevice.
~ Even though naled has been known and commercially available for a number of years prior to the present invention, and considerable research has been done with the use of naled as an insecticide, its substitution for DDVP in an insect-combatting device has not been considered feasible. Efforts to shape a collar containing naled as the insecticide were unsuccess~ul in the initial research, so that actual testins of the effectiveness of naled for controlling fieas was made quite difficult. In addition, naled was not consicered to be a likely candidate as a ~ost,~7a~
substitute for DDVP since its vapor pressure is known to be less than 2% of the vapor pressure of DDVP. Moreover, the problem of spewing with naled concentrations above about 25%
set upper limits on the amount of naled that can be used in an article. The device of the present invention containing the spew-retarding ar.ounts of finely divided silica and at least one C14 to C20 saturated aliphatic carboxylic acid or salt or ester thereof allows the use of nzled even above 25% without spew formation on the device.
By including volatile additives in the mixture used in formina the device, it has been possible to increase the naled release rate to a level which allows for the mass production of a suitable insect-combatting device.
The device in accordance with the present invention is produced to have a porous outer surface to not only release naled at a -ate higher than other~ise possible and in a greater gross amount, but also to release naled at a rate effective to control insects for a su~stantially lorger period than otherwise possible.
The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to ~e construe~ 2S limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.
dibasic lead phosphate and 0.7 p.b.w. dibasic lead stearate.
The mixture is fed to an injection molding machine and injection moldèd into the shape shown in the Figure at a temperature of 2~5F. and a pressure of from 10,000 to 2~,000 psi. The colox of the device is brownish bronze and a strong medicinal oZor emanating from the molded device is detected.
Analysis of the device arter cooling shows the naled content to be about 25% by weight.
Naled Release Rates The release rate of naled from compositions utilizable in this invention for a given surface area of a device of given thickness and surface area varies dependin~ upon not only the initial nale~
concentration, but more importantly on ~;hether or not the volatile additive which serves as a porosity control component has been used as discussed above. A device formed according to the present invention containing a sufficier.t amount for several months to control insects in the area of the device.
One significant advantzge of the naled device of the present invention over the prior art DDVP device in current commercial use is found in the pattern of release of insecticide as a gas during the first few days of activation which starts at the moment of removal from a sealed ccntainer. The initial release rate of naled during the first few days is only a fraction of the initial release rate of DDVP from comparable devices due mainly to tlie difference in vapor pressure. For naled with porosity control additive, the release rate does not decrezse noticably for a period of about 10 weeks; thereafter, the release rate gradually d~creases to about 50~ of the maximum at the end of about 20 weeks. The pattern of the release rate curve for naled from a PVC device without the porosity control co~ponent is 10567;~4 generally parallel. ~owever, the total amour.t of naled released from a device made from a formulation contairlinG the porosity control component is significantly higher (e.g., 10% or more) than that released from a device made from a similar formulation without the porosity control component which indicates tha~ more naled is being released at any given time within that 20 week period for the former device than the latter device.
Comparative ~xample A
Following the procedure of Example II and using a plastisol dispersion consistinS in parts by weight of 20 PVC homopolymer dispersion resin 12 PVC homopol~er extender resin 15 di-2-ethylhexylphthalate 2 epoxidized octyl tallate 30 naled (1,2-dibromo-2,2-dichloroe~hyl dimethyl phosphate) 20 amorphous silica particles, average particle size - microns 1 stearic acid The~cured strip contains about 25~ weight naled indicating that more of the naled initially present in this dispersion was lost during the curing process than that lost in Ex mple II.
Example VII
The procedure and quantity of Example I is repeated. The resulting device having a 1 square inch surface area is designated "A". Similar devices are made accordir.g ~o the procedure and ~uantity of Example I except that 1~ (by weight) stearic acid is utilized in place of the palmitic acid ~device "B"), 2% ~by welght stearic acid .is utilized in place of the palmitic acid (device "C"), the palmitic acid component is omitted (device "D"), the silica co~.ponent is omitted (device "~") and both the silica and palmitic acid components are omitted (device "F").
Each of these devices are suspended in a 20 cubic foot cell having dimensions of 2' x 2' x 5'. The cells consisted of a framework covered on the end and three sides with a kraft-paper-foil laminate, closed on the top with plate glass to facilitate observation.
The strips are suspended from the top in the middle o~ the cell so as not to touch the sides or bottom of the cell. The test was conducted for 16 weeks.
Visual observations of the surfaces of each device are made daily to dertermine the formation of liquid droplets of naled. The observations include the time at which the surface first appears "slick" or "wet" with bead or droplet formation, the first time at which run marks are observed and the time at which drops are actually formed on the bottom of the sample. These results are shown below in Table I.
-`-- 1()56724 ~3 _ _ __ ~ 3 3 ~ ~r _ _ _ u~
u~
~ ~ I
. ~ r~
_ u~ u~
a) 3 3 .,1 C~ O ~D
H r-l ~1 m .
3 3 .
m o ~D
u~
~1 _ .
. ~ 00 ,~
., . .
.Y ~
o,- ~
,~ ~ ~ o .. - a q I ~: R I 1 O C) t 0 ~ rl O U~
01 ~ 1 Q
~n --~ ~ o ~ ~
I ~ ~ R. O
o ~ o Id ~ Q~
1~1 ~ : Q S~ S o O S~ O
4~ ~,1 a) ~ ~ ~
~ ~ o a~ U~ 3 ~ o ~ ~s~
,1 ~> O ::1 Q
E~ h tO ~ ~
105672'~
As may be seen from the Table, the devices which did not contain both the silica component and the C14 to C20 saturated aliphatic car~oxylic acid compor.ent exhibit beading in relatively short times. Botn Device E ~acid but no silica) and Device F
(which contained neither silica nor the acid) show a slick look in about 2 weeks and beading in about 4 weeks while Device D
(silica but no acid) shows beading in about 6 weeks and drop formation in about 10 weeks. A11 of the devices of the present invention (Devices A, B and C) show beading at a considerably later time and no drop formation.
The biological activity of Devices B, C and D is measured against SRS susceptible Musca domestica.
25 of the SRS susceptible houseflies are added each day to each cell containing a device. The LT50 value (in minutes) is measured. As known in the art LT50 is the time for lethal effect on 50% of the insects introduced. Table II shows the values obtained for male SRS Susceptible houseflies. Similar results are obtained also with remale SRS Susceptible houseflies although the latter are generally more resistant.
TABLE II
-LT50 -Minutes SRS Susceptible =
LT50 ~ minutes Age of Device B C D
- Days .
29 __ 57 __ __ 5~ 62 49 68 __ 62 1056~Z4 The values obtained indicate that the addition of the acid component does not affect the biological activity of the devices. Similar results are obtained when the tests are repeated with CS.~ (NAIDM) Susceptible Musca domestica and resistant strains FC, Orlando DDT and Isolan-B Musca domestica.
The latter are pure, resistant strains of Musca domestica as recognized by the s~illed artisan.
Example VIII
Tests of blological activity or houseflies (~usca domestica), both resis~ant and susceptible strains and mosquitos r ~Culex ipiens) are conducted in the cell utilized in Example VI.
The insects are introduced into the cell containing a device made in accordance with Example I and containing 25% by weight naled. Both the LT50 and LT95 are measured. The results are shown below in Table III.
)5~i7Z4 ul In oc~
Q
X -O
~ ~ ~ o ~ ~
. , . U~
a~ u~ x ~1 C~ o CO ~ CO ~ 1--E~ ~ a~ ~ o ~D
~ ~ ~ 7 .~ o . _ ~ O In C~ O ~r o ~0 E~ ~
H ~0 U~ . ~ 1 ~J
. ~ ~ ___ ._ ~: .~ ~n .
E~ ~ U') X~ o~ oo X
. ~ ~ CO ~
S:: _ R
~,~ o X X X ~
a) E~ ~ a~ ~I o a~ ~
1~; ~ ~ r o 3 3 ::~0 . ~._ ~ O
Q.
. Q. ~l :>~- C~,~
` ~S ~ ~ C~ O ~D ~ ~ I~ ~ Lr) O ~
~ ~ XX
10567~4 The results show that. the naled-containing devices emitted the naled insecticide slowly and uniformly over a 20 week period. The devices were effective in killing both resistant and susceptible houseflies as well as the less hardy mosquitoes.
Similar tests conducted with Drosophilia melanogaster show that these insects are also killed faster than houseflies.
Similar devices containing 25 weight percent naled are hung in the hallway of a building for 20 weeks and exposed to ambient temperatures. The percent naled remaining in the devices (average of 5 devices) is shown in Table IV.
Table IV
Exposure Time Wt. ~ Naled Remaining (heeks) in Exposed Devices 0 25.25 1 24.66 2 23.22 4 21.22 8 17.38 12 15.98 16 13.28 12.34 This test further shows that the devices release the naled insecticide uniformly over a prolonged period of time.
Although some beading of the naled insecticide is noticed at a~out 16 weeks exposure, no drops or -un r.;arks are o~served at the end of the 20 wee'~ test.
Example IX
Samples of various household surfaces (aluminum roil, synthetic fiber carpet, particle board, wood, wood-semi-gloss enamel, vinyl wallpaper, wood-gloss enamel, vinyl flooring ar,d lOS6724 tempered hardboard) are placed in a cell as utilized in Example IV and exposed for 102 days to the 25 weight percent naled-containing device of Example 6. The devices are utilized in an amount of one devlce per 20 cubic feet (Run G) and two devices per 20 cubic feet (Run H). Identical sa~ples are exposed for the same time to a commercially available pest strip containing 20% by weight DDVP
(dimethyl 2,2-~i-chlorovinyl phosphate) at a rate of one device per 20 cubic feet (Run I). The adsorption of the naled or DDVP
toxicant was ~etermined by biological activity of the exposed material placed in a sealed one gallon tank in which houseflies are introduced. The LT50 values for each is measured and the time in days for each to reach an LT,G of 300 minutes by ventilation of the tank is estimated. The results are shown below in Table V.
Table V
_ Estimated Days Venti-~T50 ~ ~lir,utes lation To Reach LT50 . .. . _ . ..... _ _ G H I G H
._ _ ... __ _ . __ . . . .. . __ , Aluminum Foil No Effect ~o Effect No Effect _ _ _ Carpet-Synthetic Fiber 185 125 40 C5~ 1 CS~ 1 13 Particle Board - Vinyl 135 86 37 6 12 16 Wood 104 76 38 5 15 20 Wood Semi-Gloss Enamel 125 109 50 9 12 28 Wall paper - Vinyl 110 78 34 11 13 36 ~'ood - Gloss Enamel 125 79 40 24 30 40 Vinyl Flooring 128 98 35 9 13 42 Tempered Hardboard 135 102 50 7 15 46 ~0567Z4 The results show that considerably less naled is adsorbed on the surfaces than DDVP (as evidence by the much longer LT O times for naled). With ventilation, the naled was desorbed much faster than the DDVP. Similar tests are performed with various foods (potato, apple, bread, lettuce tomato , orange and hamburger) with 24 hour exposure.
DDVP adsorption (as compared with naledj was even higher.
DDVP is adsorbed on all foods tests with LT50 values rang-ing from 12 minutes (potato) to 51 minutes (hamburger).
Naled at the same concentration is not adsorbed on a number of the food tested and when adsorbed, exhibits LT50 values ranging from 155 minutes (potato) to 380 minutes (sliced apple).
C~mparative Example B
An investigation is lmdertaken to determine the effects of v`arious materials on the release rates and efficacy of polyvinyl chloride formulations containing about 25 weight percent naled, about 3 weight percent of a poro-sity control component and minor amounts of PVC plasticizers and stabilizers.
On the basis of an initial screening, calcium carbonate (average aluminum oxide and various silicone fluids and resins are found to unsuitable either because of their reac-tivity with naled or the porosity control component or be-cause of strong incompatibility with the PVC formulations, even at relatively low loading levels of about 5 to 15 weight percent in the formulation. Several grades of pow-dered polyethylene and ethylene-vinyl acetate resins are also tested and determined unsuitable due to their extremely high plasticizer absorption as well as their cost.
105~i7Z4 Several grades of solid glass microspheres (average particle sizes ranging from about 6 to 50 microns) are also tested. All grades of solid glass microspheres exhibit relatively bad settling proklems (greater with increasing particle size).
In addition, devices made in accordance with Example I containing 25 weight percert naled and 45 weight percent of the solid glass microspheres eY.hibit a surface slickness ~or sweating) after only 2 to 3 weeks. Similar samples made including 45 weight percent silica particles (in one instance, all particles through a 325 mesh sieve 95~ of the particles less than 40 microns and in another instance, all through a 200 mesh sieve, 95~ less than 75 microns) exhi~it sweating in 5 to 6 weeks.
Summary of Advantages The insect-combatting device of the present invention contains relatively high amounts of naled which are uniformly released over a prolonged period of time. ~laled has a reduced toxicity as compared to the prior art DDVP-containing devices and shows a substantially lower tendency towards adsorption on surfaces near the aevice.
~ Even though naled has been known and commercially available for a number of years prior to the present invention, and considerable research has been done with the use of naled as an insecticide, its substitution for DDVP in an insect-combatting device has not been considered feasible. Efforts to shape a collar containing naled as the insecticide were unsuccess~ul in the initial research, so that actual testins of the effectiveness of naled for controlling fieas was made quite difficult. In addition, naled was not consicered to be a likely candidate as a ~ost,~7a~
substitute for DDVP since its vapor pressure is known to be less than 2% of the vapor pressure of DDVP. Moreover, the problem of spewing with naled concentrations above about 25%
set upper limits on the amount of naled that can be used in an article. The device of the present invention containing the spew-retarding ar.ounts of finely divided silica and at least one C14 to C20 saturated aliphatic carboxylic acid or salt or ester thereof allows the use of nzled even above 25% without spew formation on the device.
By including volatile additives in the mixture used in formina the device, it has been possible to increase the naled release rate to a level which allows for the mass production of a suitable insect-combatting device.
The device in accordance with the present invention is produced to have a porous outer surface to not only release naled at a -ate higher than other~ise possible and in a greater gross amount, but also to release naled at a rate effective to control insects for a su~stantially lorger period than otherwise possible.
The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to ~e construe~ 2S limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for combatting insects comprising a shaped solid body having a porous surface capable of gradually and contin-ually releasing naled insecticide in an amount sufficient to provide an insecticidally active concentration of said naled over a prolonged period of time, said device comprising a synthetic resinous matrix material, from about 15 to about 35 weight percent of naled and a minor amount effective to retard spewing of the insecticide of finely divided silica particles and at least one C14 to C20 saturated aliphatic carboxylic acid or a salt or ester thereof, said device being formed from a mixture of said synthetic resin, naled, finely divided silica particles, C14 to C20 aliphatic saturated carboxylic acid or salt or ester thereof and a surface porosity control component that is non-reactive in the mixture and has a boiling point at or below the curing temperature to produce surface openings in communication with pores in said body by vaporization of said porosity control component to provide for release of naled gas at a rate effective to control insects in the vicinity of said body, but insufficient to form as spew on the body.
2. The device of claim 1 wherein the silica particles are present in an amount of from about 10 to about 35 weight percent of said device and said acid is present in an amount of from about 0.25 to about 3 weight percent of said device.
3. The shaped body of claim 2 wherein said synthetic resinous matrix material is a polyvinyl chloride.
4. The shaped body of claim 1 wherein said mixture contains a minor amount of a surface porosity control component having a boiling point of from 170 F. up to the curing temperature of the polyvinyl chloride synthetic resinous material.
5. The shaped body of claim 4 wherein said surface porosity control component is selected from the group consisting of chloroacetaldehyde, diehloroacetaldehyde, chloral, bromoacetaldehyde, dibromoacetaldehyde, bromal, bromodichloroacetaldehyde, chlorodibromacetaldehyde, bromochloroacetaldehyde, 2-bromopropanol and mixtures thereof.
6. The device of claim 1 wherein said shaped body has a regular symmetrical matrix of cavities which extend entirely through one dimension of said body, said cavities having substantially parallel axes and walls that define an essentially straight line along the said one dimension.
7. A device according to claim 1 for combatting insects, said device comprising: a discrete body of flexible synthetic resin material containing between about 20 and 30 weight percent naled and a spew retarding amount of from 15 to about 25 weight percent of finely divided silica particles and from about 0.5 to about 1.5 weight percent of at least one C14 to C20 satu-rated aliphatic carboxylic acid or a salt or ester thereof, said discrete body being formed from a mixture of said synthetic resin, naled, finely divided silica particles and from about 1 to about 3 weight percent of a surface porosity control component that is non-reactive in the mixture and has a boiling point at or below the curing temperature of said resin, said mixture being heated to its curing temperature to pro-duce surface openings in communication with pores in said body by vaporiza-tion of said porosity control component to provide for release of naled gas at a rate effective to control insects in the vicinity of said body, but insufficient to form as droplets on the body.
8. The insect control body of claim 7 wherein the synthetic resin is a polyvinyl chloride resin, the finely divided silica particles are minus 200 mesh with 90% of the particles having a size less than 75 microns, the C14 to C20 saturated aliphatic carboxylic acid is palmitic or stearic acid, the polyvinyl chloride resin is formed into said body from a liquid plastisol dispersion including said surface porosity control component by filling a casting mold pre-heated to a temperature of about 290°F., which is thereafter increased to about 360°F. and which is thereafter cooled and removed from said mold.
9. A method of controlling insects which comprises: providing a discrete body comprising a mixture of a synthetic resin, from between about 15 to 35% by weight of said strip of naled and a spew retarding amount of finely divided silica particles and at least one C14 to C20 saturated ali-phatic carboxylic acid or a salt or ester thereof; said body being formed from a mixture of said synthetic resin, naled, silica particles, saturated aliphatic carboxylic acid and a minor amount of a surface porosity control agent that is non-reactive in the mixture and has a boiling point at or below the curing temperature of said mixture, which mixture is formed into said body at the curing temperature to vaporize said control agent and pro-duce surface porosity in said body to provide for release of naled at a rate to effectively control insects in the vicinity of said body but insufficient to form as droplets on the body; and placing and maintaining said body in an area in which said insects are to be controlled.
10. The method of claim 9 wherein said mixture is formed into said body from a liquid plastisol dispersion containing polyvinyl chloride by filling a casting mold pre-heated to a temperature of about 290°F., increas-ing the mold temperature to about 360°F. in a hot air, radiant heated oven for about two minutes, and thereafter cooling and removing the body from said mold.
11. The method of claim 9 wherein said mixture is formed into said body by injection molding of said mixture.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/627,671 US3996348A (en) | 1973-11-20 | 1975-10-31 | Insect-combatting device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1056724A true CA1056724A (en) | 1979-06-19 |
Family
ID=24515612
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA264,454A Expired CA1056724A (en) | 1975-10-31 | 1976-10-29 | Insect-combatting device |
Country Status (23)
| Country | Link |
|---|---|
| JP (1) | JPS6035323B2 (en) |
| AU (1) | AU511620B2 (en) |
| BE (1) | BE847838A (en) |
| BR (1) | BR7607193A (en) |
| CA (1) | CA1056724A (en) |
| CH (1) | CH618846A5 (en) |
| DE (1) | DE2649705A1 (en) |
| ES (1) | ES452809A1 (en) |
| FI (1) | FI60344C (en) |
| FR (1) | FR2329202A1 (en) |
| GB (1) | GB1563497A (en) |
| HK (1) | HK46281A (en) |
| IE (1) | IE44398B1 (en) |
| IL (1) | IL50705A (en) |
| LU (1) | LU76099A1 (en) |
| MX (1) | MX5128E (en) |
| MY (1) | MY8200145A (en) |
| NL (1) | NL7612017A (en) |
| NO (1) | NO146258C (en) |
| NZ (1) | NZ182471A (en) |
| PH (1) | PH12778A (en) |
| SE (1) | SE433421B (en) |
| ZA (1) | ZA766190B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4202129A (en) * | 1977-12-06 | 1980-05-13 | A. H. Robins Company, Inc. | Insect-combatting device |
| JPS5650983A (en) * | 1979-10-01 | 1981-05-08 | Johnson Kk | Support for treating air |
| JPS60248602A (en) * | 1984-05-24 | 1985-12-09 | Hokko Chem Ind Co Ltd | Granular composition for agricultural purposes |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD91898A (en) * | ||||
| FR2057092A1 (en) * | 1969-08-09 | 1971-05-07 | Cruz Verde Prod | Ddvp-para-dichlorobenzene insecticide incorporating wax |
| FR2088119A7 (en) * | 1970-05-21 | 1972-01-07 | Pepro | Volatile chemical dispenser - comprising an impregnated (pvc) block drilled to adjust the surface/valume ratio for releasing chemic |
| US3918407A (en) * | 1973-11-20 | 1975-11-11 | Robins Co Inc A H | Pet collar |
-
1976
- 1976-10-18 IL IL50705A patent/IL50705A/en unknown
- 1976-10-18 ZA ZA766190A patent/ZA766190B/en unknown
- 1976-10-26 PH PH19051A patent/PH12778A/en unknown
- 1976-10-27 CH CH1355876A patent/CH618846A5/en not_active IP Right Cessation
- 1976-10-27 FR FR7632417A patent/FR2329202A1/en active Granted
- 1976-10-27 SE SE7611947A patent/SE433421B/en not_active IP Right Cessation
- 1976-10-27 IE IE2382/76A patent/IE44398B1/en unknown
- 1976-10-28 GB GB44883/76A patent/GB1563497A/en not_active Expired
- 1976-10-28 ES ES452809A patent/ES452809A1/en not_active Expired
- 1976-10-28 FI FI763077A patent/FI60344C/en not_active IP Right Cessation
- 1976-10-29 LU LU76099A patent/LU76099A1/xx unknown
- 1976-10-29 NO NO763692A patent/NO146258C/en unknown
- 1976-10-29 MX MX765037U patent/MX5128E/en unknown
- 1976-10-29 CA CA264,454A patent/CA1056724A/en not_active Expired
- 1976-10-29 BE BE171964A patent/BE847838A/en not_active IP Right Cessation
- 1976-10-29 NZ NZ182471A patent/NZ182471A/en unknown
- 1976-10-29 DE DE19762649705 patent/DE2649705A1/en not_active Ceased
- 1976-10-29 NL NL7612017A patent/NL7612017A/en not_active Application Discontinuation
- 1976-10-31 BR BR7607193A patent/BR7607193A/en unknown
- 1976-11-01 JP JP51131563A patent/JPS6035323B2/en not_active Expired
- 1976-11-01 AU AU19192/76A patent/AU511620B2/en not_active Expired
-
1981
- 1981-09-17 HK HK462/81A patent/HK46281A/en unknown
-
1982
- 1982-12-30 MY MY145/82A patent/MY8200145A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NO146258B (en) | 1982-05-24 |
| GB1563497A (en) | 1980-03-26 |
| NO763692L (en) | 1977-05-03 |
| JPS6035323B2 (en) | 1985-08-14 |
| ES452809A1 (en) | 1978-01-16 |
| BR7607193A (en) | 1977-09-13 |
| SE433421B (en) | 1984-05-28 |
| FI60344C (en) | 1982-01-11 |
| IL50705A (en) | 1979-07-25 |
| ZA766190B (en) | 1977-09-28 |
| IE44398L (en) | 1977-04-30 |
| MX5128E (en) | 1983-03-25 |
| JPS5257326A (en) | 1977-05-11 |
| NZ182471A (en) | 1979-04-26 |
| MY8200145A (en) | 1982-12-31 |
| FR2329202B1 (en) | 1980-04-04 |
| AU1919276A (en) | 1978-05-11 |
| HK46281A (en) | 1981-09-25 |
| NL7612017A (en) | 1977-05-03 |
| FI763077A (en) | 1977-05-01 |
| SE7611947L (en) | 1977-05-01 |
| AU511620B2 (en) | 1980-08-28 |
| BE847838A (en) | 1977-02-14 |
| FI60344B (en) | 1981-09-30 |
| CH618846A5 (en) | 1980-08-29 |
| PH12778A (en) | 1979-08-17 |
| NO146258C (en) | 1982-09-01 |
| LU76099A1 (en) | 1977-12-01 |
| IE44398B1 (en) | 1981-11-18 |
| FR2329202A1 (en) | 1977-05-27 |
| IL50705A0 (en) | 1976-12-31 |
| DE2649705A1 (en) | 1977-05-05 |
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