CA2293867A1 - Insect repellent polymer - Google Patents

Abstract

The invention comprises a polymer or polymeric material that is treated with an insecticide. The insecticide treatment insures that any articles produced from the polymeric material will have insect resistance characteristics. The treated polymeric material is transformed into an insect repellent polymeric article through any number of standard commercial processes. Insect repellent articles produced from the polymeric material of the invention are suitable for use in a variety of different building or construction applications.

Description

INSECT REPELLENT POLYMER
Background of the Invention Field of the Invention The present invention relates to an insecticide treated polymeric product that is used to manufacture treated polymer articles. More particularly, the invention pertains to treated polymeric articles for use in construction and building applications such as insulating foams.

2. Description of the Prior Art For many years polymeric foams have been used as insulating materials in the construction industry with a high degree of success. Recent legislation in certain building code jurisdictions, however, has banned the use of these polymeric foams in certain applications because of infestation problems. These bans have limited the use of these highly effective building materials and seen less effective materials used in their place.
The problem is twofold in nature. First, the insects attack (tunnel or bore) the polymeric foam reducing the functional and physical properties of the foam. Second, the insects are hidden from view when they are tunneling in the foam making their detection more difficult.
The treated polymeric materials can be transformed into any number of treated f coshed polymeric articles that includes insulating foams. These insulating foams are resistant to insect attack therefore they do not suffer from functional or physical property damage and they do not provide hidden avenues for the insects to enter the building. The insect resistant polymeric articles can then be used in combination with standard pest control practices to provide a significant barrier to infestation for a new building or construction project.
Although many insecticides are effective against the action of boring insects, these insecticides usually must be applied repeatedly at intervals that can range from every few days to every few months to annually to remain effective. This need to re-apply the insecticides is a result of the insecticide being volatile, degrading in some way, or leaching from the system it is protecting. To this end, the typical application concentration initially applied is of a higher concentration than that which is needed to be effective. The concentration can drop rapidly, however, and within a relatively short period of time this concentration could have fallen below the minimum required concentration for efficacy. Further, if the insecticides are applied in concentrations sufficiently high to last for longer periods of time, they can pose ecological concerns, 2 0 h~~ health concerns, health concerns for pets or livestock, and may present unpleasant odors or other undesirable attributes.
To this end, a number of techniques for the controlled release of chemicals such as insecticides have been developed in recent years. These methods employ polymer matrices and microcapsules to release insecticide.
Cardarelli U.S. Pat. No. 4,400,374 discloses the use of polymer matrices generally 30 made of polyethylene, polypropylene, ethylene vinyl acetate, polyamide, polystyrene, polyvinyl acetate, or polyurethane to control the release of insecticides such as the insecticide commercially available under the tradename Dursban. The polymer matrices disclosed in U.S. Pat. No. 4,400;374, incorporate porosigen and a porosity reducing agent which upon contact with soil moisture or an aqueous environment dissolves the matrix.

Similarly, Caraderelli U.S. Pat. No. 4,405,360 relates to a polymer release matrix which can be composed of polyamide, polyurethane, polyethylene, polypropylene, polystyrenes and other polymers. The control release mechanism works in combination with a porosigen to release a herbicide in a moist environment.
A disadvantage of the Caraderelli methods is the necessity of sufficient moisture to dissolve the matrix. Periods of dryness, while extending the life of the matrix, would result in a decrease in the insecticide concentration thereby permitting access to the insects. In addition, the longevity of the matrix is variable and dependent upon moisture content.
Wysong U.S. Pat. No. 4,435,383 teaches the use of a controlled release mechanism for insecticides including carbamates, organothiophosphates, organophosphates, perchlorinated organics and synthetic pyrethroids. The release mechanism comprises a hydrophobic barrier monomer namely styrene and/or methyl styrene in combination with a monomer selected from one or more unsaturated mono- or di-carboxylic acids.
Another reference, Tocker U.S. Pat. No. 4,282,209 discusses a process for the preparation of insecticide-polymer particles. The insecticide, methomyl, is used to control insects which attack tobacco, cotton or agricultural crops. Methomyl is dissolved with polymers such as polyamides, urethanes and epoxies to provide extended residual insecticidal activity.
A second Tocker patent, U.S. Pat. No. 4,235,872, discloses the use of slow-release insecticide microcapsules having a core of methomyl surrounded by a cover of allaromatic, uncrosslinked polyurea. In the arrangement disclosed in this patent, methomyl is used to protect vegetables, field crops and fruit crops.
A sixth reference, Young et al. U.S. Pat. No. 4,198,441, discloses the use of insecticides such as Du_rsban in a controlled release matrix comprising an organopolysiloxane, a hydrolyzable silane and a hydrolyzable organic titanium.
Additionally, Young et al. U.S. Pat. No. 4,190,680 teaches the use of a controlled release device for insecticides such as Dursban utilizing a hydrolyzable organic titanium compound.
Von Kohorn et al. U.S. Pat. No. 4,160,335 discloses a mode of dispersing insect control substances by applying stripes to sheets of cellophane. The insect control substance, which can include Dursban, is placed in a polymer well.
Voris et al. U.S. Patent No. 5,801,194 discloses a method and device which prevent the intrusion of insects onto wood structures by using a controlled release device capable of releasing insecticide. In the disclosed method, the device maintains a minimal effective level of insecticide for a predetermined period of time.
The Voris reference teaches the creation and maintenance of an effective exclusion zone lasting several years or more. One disadvantage of the Voris controlled release system is that it requires the use of a dual insecticide system to compensate for the differences in release rates of various insecticides. Further, it is necessary for the Voris apparatus and method to start with an elevated level of insecticide which can be slowly released into the environment over time.
An alternative approach is to apply insecticides that are relatively benign to the environment. Such an approach has been taken by Savoy, U.S. Patent No.
5,194,323 where a boron based insecticide (di-sodium octoborate tetrahydrate or commercially know as TIM-BOR~) is used to treat expandable polystyrene (EPS) foam insulation that is sandwiched between two exterior skins of oriented strand board by a urethane laminating cement. The problem with this approach is that the necessary concentration of the TIM-BOR needs to be very high when this approach is reduced to practice.
Commercially, the concentrations can be 2500 ppm and more.
Such concentrations are supported by a second patent by Winter. The Winter Patent, No. 5,224,315, cites very high concentrations (2-10 weight percent) in order for the TIM-BOR to be effective. These high concentrations can greatly effect the quality of the finished polymeric article, in the case of the last two cited patents, EPS. The high level of insecticide interferes with the ability of the EPS to fuse with itself creating foam materials that are weaker (lower flexural and compressive strengths as compared to 2 0 untreated material) then their untreated counter-parts. In some instances, this problem can be overcome by extreme processing conditions during the molding of the EPS
foam.
The aggressive molding conditions require longer molding cycle times thereby reducing the effective capacity of the molding equipment. While these aggressive or extreme molding conditions can be used to alleviate the mechanical strength problem, they are not a desirable solution because of the limits on molding equipment capacity that result.
30 ~ s~'Y~ the prior art discloses two possible means by which to protect polymeric articles. The first discloses the use of an insecticide incorporated into a polymer matrix as controlled release agents. These agents are designed to leach out of the polymer matrix and will eventually drop below minimum effective levels.
The second discloses the use of an insecticide that is relatively benign to the environment, but one that requires high concentrations to be effective. These high concentrations can compromise the quality of the finished polymeric article. Alternatively, the limitations on the quality of the finished molded articles created by the high concentrations can be overcome with extreme processing conditions. These extreme processing conditions however, place limitations and or restrictions on the capacity of the equipment used to transform the polymeric material into the finished polymeric articles.
Desirably, a polymeric material could be treated with a non-volatile insecticide that was compatible with the polymeric material and any finished polymeric article produced from that material. The insecticide would be designed to reside in the finished article rather than to permeate or leach out into the environment as indicated in the previously cited works. In order for such a design to be effective, the insecticide must have a certain repellency characteristic to insure that the insects do not attack the article being protected since the insecticide will not be emitted into the surrounding environment. Additionally, it is desirable that the insecticide will provide such characteristics at concentrations low enough to not interfere with the production of the finished polymeric articles from the treated polymeric material. Lastly, the insecticide would be highly effective for boring insects such as termites and carpenter ants.
SUMMARY OF THE INVENTION
The invention comprises a polymer or polymeric material (the terms "polymeric material" and "polymer" are used interchangeably throughout) that is treated with an insecticide. The insecticide treatment insures that any articles produced from the polymeric material will have insect resistance characteristics. The treated polymeric material is transformed into an insect repellent polymeric article through any number of standard commercial processes. Insect repellent articles produced from the polymeric material of the invention are suitable for use in a variety of different building or construction applications.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Sect resistant characteristics are desirable because insect attack will lead to degradation of untreated finished polymeric articles. This degradation can be observed as loss of mechanical strength properties such as flexural or compressive strength, deterioration in appearance, or loss in insulating value in the case of a foam insulation product. Such degradations will pose serious concerns when these finished polymeric articles are used in building and construction projects. Additionally, treatment with a suitable insecticide is especially important for polymeric foams (used in construction or other applications like seedling trays for example) as these low density lightweight finished foam articles are even more susceptible to attack then most non-foamed polymeric articles.
The polymeric product that is treated with the insecticide can come from the family of thermoplastic polymers, thermoset polymers, elastomeric polymers, and blends or copolymers thereof. The choice of polymeric product is highly dependent on the final applications of the finished polymer article. Examples of polymers that may be used include polyolefins, polyvinyl polymers, polyamides and polyurethanes. The polyolefins can be either straight or branched hydrocarbons and include such examples as polyethylene and polypropylene. Examples of the polyvinyl polymers include polystyrenes (rubber or elastomer modified, unmodified, and co-polymers there of such as acrylonitrile-butadiene-styrene or ABS), polyvinyl chlorides, polyvinyl alcohols and esters and their derivatives, and acrylic polymers. The polyurethanes include polyurethane foams, polyisocyanurate foams and polyurethane elastomers.
The insecticide used in the preferred embodiments is selected from the family of insecticides including pyrethroids and 1H-Pyrazole-3-carbonitrile, 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl], commonly known as fipronil. Additionally, those schooled in the art will recognize that any number of other insecticides can be used effectively. These include bifenthrin., lamda-cyhalthrin, cyfluthrin, esfenvalerate, cypermethrin, permethrin and natural pyrethrin. The choice of the insecticide is based on a number of factors including:
~ compatibility with the processing conditions that will be employed to convert the monomer to a polymeric material if the insecticide is added during the polymerization.
~ compatibility with the processing conditions that will be used to convert the polymeric material into a finished polymeric article.
~ compatibility with the polymeric material itself efficacy (required concentration) of the insecticide against the desired pest Environmental issues also play an important role in the selection of the insecticide. These factors include:
~ volatility of the material ~ solubility of the material in water or other solvents ~ thermal, ultraviolet (if exposed to sunlight), and biodegradable stability ~ leachability of the material from the finished polymeric article into soil or groundwater Additionally the efficacy, and as a result, the necessary concentration of the insecticide can play an important role in determining the quality of the finished polymeric article as previously discussed. Insecticides that require high concentrations, i.e. 2500 ppm and more, can have negative effects on the quality of the finished articles. A
significant advantage to the system embodied here is that the insecticide can be applied at very low levels, 1000 ppm or less, which greatly reduces the impact of the insecticide on the quality of the finished article.
The insecticide can be "incorporated" into the polymeric product in numerous ways and at various stages in the process of producing either the polymeric material or the finished polymeric article. For purposes of this invention, the term "incorporate"
refers to coating, dipping and spraying, as well as more intimate chemical bonding.
The first opportunity to add the insecticide to the polymeric material is through incorporation of the insecticide into the polymer during the reaction or polymerization process. The insecticide can be incorporated into the polymer in a manner similar to the incorporation of other additives while the monomer is converted to polymer.
Either the insecticide can be chemically bonded to the polymer chains or it can be occluded in the free volume between the polymer chains.
Examples of other polymer additives that are currently introduced in this fashion would include internal mold release agents which provide processing advantages to the polymeric material, any number of flame retarding chemicals which add flame resistance to the finished polymeric articles, and any number of internal plasticizers which serve to soften the finished polymeric article for either processing advantages or end use properties.
The second opportunity to add an insecticide to the polymeric material is as an external coating after the polymerization has been completed but still during the normal process of manufacturing the polymeric material (i.e. in subsequent processing steps after the monomer has been converted to polymer). The insecticide can either be a solid, a solid dissolved in a suitable solvent (solution), or a solid dispersed in a suitable carrier fluid (suspension). It can be added with other external coatings such as lubricants during the manufacturing process of the polymeric material or in a separate processing step.
Additionally, the mixing can occur either as a dry blend or as a melt blend.
Dry blending includes the addition of the insecticide to the polymeric material in any number of conventional mixers such as a V-blender, or ribbon blender just to name a few.
The insecticide can be added as a second dry ingredient, or sprayed into the mixer as a solution or suspension as cited above. Melt blending includes applying the insecticide as above prior to melting the polymeric material, adding the insecticide as a second dry feed to the melt mixer, or injecting the dissolved or suspended insecticide into the melt mixer.
Such melt mixers could be, but are not limited to, extruders and Farrel Continuous Mixer.
In any case, the mixing of the polymeric material and the insecticide can be done batch or continuous.
It is also possible to spray (prepared as a solution or suspension) the insecticide onto the polymeric material after the normal process of converting the monomer to to polymer just prior to the conversion of the polymeric material to a finished polymeric article. The insecticide may be sprayed into a pneumatic conveying tube, into a screw conveyor, onto a weigh belt or any other device that is being used to convey or process the polymeric material through the processing steps where it is being converted to a finished article. It may be sprayed onto the outside of the finished polymeric article or the finished article could even be dipped into a solution containing the insecticide. These two processes, however, are not as ideal as the methods shown in the previous examples because the insecticide is no longer physically incorporated into the finished polymeric article, which greatly reduces the mechanism which "fixes" the insecticide to that article.
The preferred polymeric material is polystyrene and the preferred insecticide is alpha-cyano-pyrethroid. Ranges of from about 1 part per million (ppm) to 1000 ppm, i.e., less than O.lpercent by weight of the polymer, of the alpha-cyano-pyrethroid by weight of ~e polymer are preferred. More preferably, the concentration of insecticide ranges from 10 to 500 ppm. Concentration may vary, however, depending on the point and method of application. The alpha-cyano-pyrethroid is available commercially under the trade name Delta-Tech~ and is manufactured by AgrEvo as an insecticide in the crop industry.
The inherent advantage that the claimed invention has over other potential treatments is that it contains a repellent that keeps the insects from damaging the final ~icle for which the polymer is ultimately used. In expandable polystyrene foam, for example, the insecticide is part of the foam immediately, rather than remedially. This helps maintain the physical and functional properties of the foam such as mechanical strength and thermal insulating properties.

Preferably, the combined polymer/insecticide is produced in the form of a bead or pellet. The beads or pellets can be any convenient size depending upon the intended use, such as 1 to 25 millimeters in diameter (or width and thickness, if rectangular) by 2 to 20 centimeters or more in length. Furthermore, in order to fit specific user needs, the dimension of the pellets can easily be adjusted.
Insulative foam made from the polymer/insecticide pellets can be utilized as one insect repellent polymeric article of the invention. By producing a foam with the insecticide already incorporated into the polymer, the integrity and insulating ability of the foamed article is maintained against boring insects and the sand, water, dirt and other foam-weakening materials associated with the insects. The foam may be molded or extruded, depending on the final application, into a variety of finished polymeric products. Examples of possible applications include exterior foundation wall insulation peels, insulation cores in structural panels, concrete forms, extended sheet products, molded block and articles cut therefrom, as well as adhesive systems used to attach insulation to foundation walls.
Preferably, the foam is made from extruded polystyrene, expandable polystyrene or polyurethane. Most preferably, the foam is made from expanded polystyrene.
The making of expandable particles of styrene-type polymers is well known. It comprises two basic aspects, polymerization of styrene-type monomer and the impregnation of the polymer with a blowing agent. The polymerization reaction is usually conducted either in bulk or in suspension. Where the bulk polymerization method is used to prepare the polymer the impregnation step is usually conducted in a separate reactor. In the case of the suspension polymerization method the impregnation may be carned out either as a step contiguous to the polymerization by introducing the blowing agent to the reactor at a certain point during the reaction or at the completion of the polymerization, or as a step completely separate and independent of the polymerization. In the latter case, the bead product of the suspension polymerization is taken from the reactor, washed, and the impregnation step is conducted by re-suspending the polymer in water. The latter method has the advantage that out of the total polymer beads obtained from the suspension polymerization, one can select only those beads having a particle size suitable for expandable styrene-type polymer usage and use the rest for other purposes.
The impregnated particles are usually pre-expanded and aged before molding to stabilize the bead structure and control the final density of the molded article. The pre-expansion is carried out in either a batch or continuous expander using steam to heat the unexpanded p~icles above the softening point. The blowing agent in the resin causes the beads to expand to the density required for the final application. The expanded beads, after a brief period of stabilization, are steam chest molded into the finished foam which may be either a specific shape ready for end use or a block of foam requiring further hot wire fabrication.
In applications requiring the use of an extruded product, solid polymeric, preferably polystyrene, pellets are processed in an extruder where a blowing agent is introduced to create the foam. The insecticide is either added to the polymeric material before the extrusion processing a separate mixing process or during the extrusion process as an additional additive.

The following examples help to illustrate the preferred embodiments. Example 1 refers to the method of incorporating the insecticide into the polymeric material during the reaction or polymerization process. For the purposes of the example, expandable polystyrene (EPS) has been chosen as the polymeric material. The insecticide that has been chosen is a-cyano-pyrethroid. The polymerization process chosen is a suspension process where the blowing agent is incorporated into the polymer beads during the polymerization. Example 2 refers to the method of incorporating the insecticide into the polymeric material during the addition of external coatings and lubricants.
For the purposes of the example, expandable polystyrene (EPS) has again been chosen as the polymeric material with the insecticide being a-cyano-pyrethroid. Examples 3-5 illustrates how the insecticide can be added to the polymeric material during the conversion of said material into a finished polymeric article.
2 0 E~pLE 1 A mixture of 87 parts water, 0.16 parts of sodium pyrophosphate, and 0.27 parts of magnesium sulfate heptahydrate was reacted while stirring at ambient temperature in a stainless steel pressure resistant vessel. To this mixture a mixture of 100 parts styrene, 0.14 parts benzoyl peroxide, 0.5 parts dicumyl peroxide, 0.62 parts hexobromocyclododecane , and 0.05 parts a-cyano-pyrethroid or deltamethrin was added.
30 The vessel was heated for at least 2 hours at a constant rate to 85°C and then to 130°C
over a period of at least 4 hours. Fifty to seventy-five minutes after the vessel has reached 80°C, a solution of 3 parts of a 10% aqueous solution of poly-n-vinylpyrrolidone was added to the reaction mixture. After an additional 100-150 minutes 7.5 parts of n-pentane was added to the reaction vessel. Upon reaching 130 °C, the vessel was held at that temperature for 3 hours, whereupon it was cooled to ambient temperature over three hours. The EPS product, which is spherical in shape with sizes range from 0.4-1.8 mm then needs to be dried, screened, and coated with external lubricants. The resulting EPS
was screened to 0.6-1.3 mm which is a size typical for most construction applications.
The resulting polymeric material was easily foamed and molded into polystyrene foam insulation through known industrial processes. In this example, all of the polymeric material produced in the reactor is treated with the insecticide.

A polystyrene polymer was prepared substantially as described in Examplel, however, the insect repellent material was not included. During the normal commercial production of such polymers, the polymeric beads are contained in a water suspension.
2 0 The water is then removed and the beads are dried. The dried beads were screened to 0.6-1.3 mm and then coated with 0.15 weight percent of a mixture of powdered lubricants and insecticide. The powder blend included a mixture of lubricants commonly used in the industry as screening aids and anti-lumping agents as well as the insecticide, alpha-cyano-pyrethroid. The lubricants accounted for 80 weight percent of the total coating blend while the insecticide accounted for the other 20 weight percent. The total amount 30 of insecticide added to the polymeric material based on weight percent of the polymeric material was 0.03 weight percent or 300 ppm. The resulting EPS product was easily foamed and molded into polystyrene foam insulation through known industrial processes.
A further advantage of adding the insecticide to the EPS beads during the external coating stage of the process is that it allows the insecticide to be incorporated into beads of a select size rather then all of the beads that have been produced in the polymerization.

A polystyrene polymer was prepared substantially as described in Examplel, l0 however, the insect repellent material was not included. The EPS is fed via a screw conveyor to a batch pre-expander at a rate of 750 lbs per hour (15 lbs per batch). The insecticide, a-cyano-pyrethroid, is metered into the inlet of the screw conveyor at a rate of 0.225 lbs per hour. Alternatively, the a-cyano-pyrethroid can be added to the weigh hopper as the beads are filling it prior to addition to the batch pre-expander. The later approach is consistent with the methods employed to color EPS commercially by those skilled in the art of expanding and molding EPS. Once the treated EPS has been expanded to the desired density, typically about 0.9 pounds per cubic foot (pcf), it is 2 0 molded and then if necessary, hot wire cut material consistent with standard commercial practice.

A polystyrene polymer was prepared substantially as described in Examplel, however, the insect repellent material was not included. The EPS is fed via a screw conveyor to a batch pre-expander at a rate of 750 lbs per hour (15 lbs/batch).
The 30 insecticide, oc-cyano-pyrethroid, is suspended in water or other suitable liquid and sprayed into the batch expander during the expansion process at a rate of 0.225 lbs of insecticide per hour or 0.0045 lbs per batch. The method of metering such small quantities is consistent with the methods employed to add oil as a processing aid to EPS

commercially by those skilled in the art of expanding and molding EPS. Once the treated EPS has been expanded to a density of 0.9 pcf, it is molded and then hot wire cut into insulation material consistent with standard commercial practice.

A polystyrene polymer was prepared substantially as described in Examplel, however, the insect repellent material was not included. The EPS is fed via a screw conveyor to a batch pre-expander at a rate of 750 lbs per hour (15 lbs/batch) to a density of 0.9 pcf. The pre-expanded beads are conveyed to a storage silo and aged for a period of 4-24 hours which is consistent with current industrial practice. The beads are then pneumatically conveyed to a block mold and molded into a foam block or billet.
The insecticide, a,-cyano-pyrethroid, which is suspended in water or other suitable liquid is sprayed onto the pre-expanded beads at a rate of 0.03 weight percent as they are pneumatically conveyed to the block mold. The method of addition is consistent with the methods employed to add oil as a processing aid to EPS commercially by those skilled in the art of expanding and molding EPS. Once the treated billet has been molded, it is hot wire cut, if necessary into material consistent with standard commercial practice. A
further refinement to this example would be to include the insecticide in the oil that is already being added during the process as a processing aid.

Claims (17)

1. A method of making an insect repellent polymeric article comprising the following steps:
providing a polymer selected from the group consisting of thermoplastic polymers, thermoset polymers, elastomeric polymers and copolymers thereof;
incorporating from about 1 part per million to 1000 parts per million by weight of the polymer of an insecticide into the polymer; and forming the insecticide treated polymer into an insect repellent polymeric article.

2. The method of claim 1, wherein the insecticide is selected from the group consisting of pyrethroids, 1H-Pyrazole-3-carbonitrile, 5-amino-1-[2,6-dichloro-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl], bifenthrin., lamdacyhalthrin, cyfluthrin, esfenvalerate, cypermethrin, permethrin and natural pyrethrin.

3. The method of claim 1, wherein the amount of insecticide incorporated into the polymer is from about 10 parts per million to 500 parts per million by weight of the polymer.

4. The method of claim 1, wherein the insecticide is incorporated into the polymer during polymerization of the polymer by a method selected from the group consisting of chemically bonding the insecticide to the polymer chains and occluding the insecticide in the free volume between polymer chains.

5. The method of claim 1, wherein the insecticide is incorporated into the polymer as an external coating.

6. The method of claim 5, wherein the insecticide is added in a form selected from the group consisting of a solid, a solid dissolved in a suitable solvent (solution) and a solid dispersed in a suitable carrier fluid (suspension).

7. The method of claim 6, wherein the insecticide is added in a form selected from the group consisting of a dry blend and a melt blend.

8. The method of claim 1, wherein the insecticide is incorporated into the polymer by a process selected from the group consisting of batch processing and continuous processing.

9. The method of claim 6, wherein the insecticide is incorporated into the polymer by spraying the insecticide onto the polymer prior to conversion of the polymer into a finished polymeric article.

10. The method of claim 9, wherein the insecticide is incorporated into the polymer by dipping the polymer into a solution containing the insecticide.

11. The method of claim 1, wherein the polymer is a polystyrene and the preferred insecticide is alpha-cyano-pyrethroid.

12. The method of claim 1, wherein the insect repellent polymeric article is produced in a form selected from the group consisting of beads and pellets.

13. The method of claim 1, wherein the insect repellent polymeric article is an insulative foam made from a polymer selected from the group consisting of expandable polystyrene, extruded polystyrene and polyurethane.

14. The method of claim 13, wherein the polymer used to make the insulative foam is an expandable polystyrene.

15. The method of claim 13, wherein the foam is formed into a finished polymeric product by a method selected from the group consisting of molding or extruding.

16. The method of claim 15, wherein the finished polymeric product is selected from the group consisting of exterior foundation wall insulation panels, insulation cores in structural panels, concrete forms, extended sheet products, molded block and articles cut therefrom, and adhesive systems used to attach insulation to foundation walls.

17. The method of claim 14, wherein the insecticide is incorporated into the expandable polystyrene by adding it to the expandable polystyrene at a point selected from the group consisting of prior to pre-expansion, during pre-expansion and after pre-expansion.