FR2698632A1 - Prods. for controlled release of active substance - comprising low-density polymer foam - Google Patents

Abstract

New prods. comprise a polymer foam contg. an active substance (I) releasable into the surrounding medium, where the foam has a density of 5-20 g/l. Also claimed is the prodn. of a prod. as above by dispersing (I) in a prepolymer or polymerisable mixt., which is then polymerised to form a rigid or flexible solid foam with a density of 5-20 g/l. USE/ADVANTAGE - The prods. are useful for controlled release of pesticides, e.g. insecticides (including ectoparasiticides), bactericides, molluscicides and rodenticides, repellants, attractants, pheromones, air fresheners, deodorants, etc. The prods. have a lower density than prior art foams (cf. DE 2928591 and US 4618629) and thus have a larger contact area with the surrounding medium, so that (I) is released more efficiently over long periods.

Description

 The present invention relatesîune composition of plastic in the foam state, containing an active substance which it releases gradually for an action on the environment.

 It is known to use polymer foams, loaded with more or less volatile substances, to act on the atmosphere, for example with a view to destroying insects and / or harmful rodents, to disinfect the atmosphere. , to scent it, or for other purposes. In particular, polyurethane foams are often applied. As in practice the effectiveness of known products generally leaves something to be desired, the emission of active vapor being too slow, the product quickly becoming inactive, various solutions have been proposed to improve them. We therefore use the addition of fine, adsorbent powders (GB 2 034 728), the use of foams (whose specific weight is between 93 and 160 g / liter (DE 2 928 591, page 7), when using the active substance in the form of a resin (US 4 618 629) etc.

 Despite the various improvements in the prior art, the practical use of the products in question remains subject to various drawbacks; in particular, when it comes to destroying insects, reptiles or murids, the action is generally insufficient.

 The invention, described below, resides in that products with considerably increased activity are obtained by the association of the active substance with a very light polymer foam, in particular with a specific weight of approximately 5 to 20 g / l. A preferred embodiment consists in using rigid polyurethane foams with a specific weight of between 6 and 15 g / l, and especially from 7 to 10 g / l.

 Such foams have never been used until now, as can be seen in the documents cited above; the lightest weighed 25.6 g / l (US 4,618,629, examples 1 to 3).

 With the extra-light foams according to the present invention, the active substance or substances having been introduced, preferably, into the mixture before its polymerization, very rapid destruction of harmful animals is obtained, the odorization or deodorization of the ambient atmosphere, and the active substance is used with very good yield.

 Of course, the invention applies to various active substances, such as repellents, attractants, pheromones and others; the foam can be used in platelets or pieces, or in a powder obtained by spraying them.

One can, for example, use, as active substances, the various products, known in the industry under the names like MALATHION,
PARATHION, ENDOSULFAN, ALPRIN, NORBOMIDE, CYPERMETRHINE, DDVP, DELTAMETHRINE, DYCHLORVOS, PYRIMIPHOS METHYL, etc.

 The present invention provides the advantage of a much stronger diffusion of the active material than in the case of previously known products. The plastic material is there in a physical form such that the active component, in particular insecticide, perfume, attractant or other, is in contact with the atmosphere by a considerably larger surface than in the prior art.

In addition, it can remain effective much longer, being dispersed throughout the entire mass of the plastic support. It should also be noted that the new products according to the invention can be biodegradable, which represents a marked advantage.

 Preferably, in the composition loaded with active agent throughout its mass, the pores of more than 0.2 mm in diameter represent at least 10% of the total of the pores. Particularly effective products have for the most part pores or / and cells of approximately 0.6 to 6 mm.

 In the composition according to the invention one or more active agents (bactericides, insecticides, molluscicides, raticides, or others) are dispersed throughout the mass of a plastic material, the latter being in the form of a solid foam.

 The foam is more or less rigid or flexible, depending on the material in which it is to be used; its cells are - at least partially open.

 Suitable for the formation of the new composition, the various polymers capable of being put in the form of foam, in particular polystyrenes, polyacrylates or methacrylates, in particular methyl or ethyl, polycarbonates and - above all - polyurethanes.

 Since these compositions are generally used in sheets, plates, plates, rods or other solids, which can be fixed to surfaces of dwellings, furniture, refrigerated cabinets or other devices, it may be useful for them to be rigid or more or less flexible . A possible constituent of these products is therefore a plasticizer.

 The constitution of these solid plastics foams most often comprises 0.5 to 20% by weight of one or more active agents, such as insecticides, raticides, antilimaces, repellents, etc., relative to the weight of the plastic present.

 The most widely used amounts of active agents are approximately 5 to 15% of the total product.

When a plasticizer is used, its proportion can vary widely; it is generally of the order of 1 to 15%
I1 is often indicated to incorporate into the composition one or more compounds intended to exert various actions, in particular attractants, colorants, perfumes, catalysts, fillers, surfactants, etc., the content of which can range from 0.1 to 30%. The presence of mineral fillers, for example silica, alumina, silicoaluminates or activated carbon to regulate the emission of the active agent, or its consumption by pests, especially in the case of agents with relatively volatility strong.

 In a particular embodiment, the composition is added with a dye or a pigment which discolours in the open air with the same speed with which the active agent becomes exhausted from the composition thus, the discoloration of the product indicates the end of its activity.

 The preparation of the new compositions consists in dispersing one or more active agents in one or more monomers or prepolymers and allowing the polymerization to occur after or during this dispersion, while ensuring gas evolution within the mixture, so as to put it under the form of a foam.

 This preparation therefore includes appropriate stirring, achievable by any means known in the art.

 In order to avoid any deterioration of the active agent and its possible reaction with the medium in polymerization, the process according to the invention is carried out at temperatures as low as possible; the above operations take place below 100 "C and preferably between 0 and 60" C or, better still, between 20 and 50 "C. Cooling means are provided, to prevent the spontaneous rise in temperature during polymerization.

 It goes without saying that, depending on the shape to be given to the composition, the mass can be poured into a mold or onto a plate, to then be cut or crushed.

 The new compositions, their applications and their method of preparation are illustrated by the nonlimiting examples which follow.

EXAMPLE 1
A viscous but liquid prepolymer of polystyrene is first prepared by heating at 60 ° C. 1000 g of styrene supplemented with 1 g of benzoyl peroxide and 70 g of tributyl phosphate as a plasticizer.

 To the liquid prepolymer thus obtained, 80 g of "MALATHION" (O, 0-dimethyl dithiophosphate of 1,2-dicarbethoxyethyl; C10H1906PS2) 1 insecticide acting by contact, by ingestion and by inhalation are added.

 The temperature is fixed at 45 ° C. and the mixture is stirred continuously, passing nitrogen bubbles through the viscous mass by means of spoons of sintered glass, so that the foam formed has a specific gravity of 12 g / l.

 The viscous foam obtained is poured into 50 × 100 × 10 mm wafers which are allowed to harden by cooling. The pores of these plates have diameters from 0.2 to 6 mm. Arranged in a place frequented by flies and mosquitoes, in parallel with insecticide plates, made of plastic of the known type, commercially available, they kill a considerably greater number of insects than the latter.

EXAMPLE 2
Polyurethane foam loaded with insecticide is produced by stirring at 30 -40 C of the following mixture
675 g of butylene glycol HO- (CH2) o-OH
1400 g of toluylene diisocyanate CH3-CH4- (NCo) 2
146 g water (H2O)
3 g of triethylamine (C2H5) 3N
120 g of "PARATHION", active insecticide against insec
tes and mites by ingestion and by inhalation (C10H4NO5PS).

 By a known reaction, water produces CO2 forming a foam, while the amine acts as a catalyst.

 The product obtained, used in the form of platelets, or crushed, actively destroys insects for a long time. Its specific weight is approximately 10 g / l.

EXAMPLE 3
The preparation of a selective raticide composition is carried out as described in Example 2, except that in place of the "PARATHION", 90 g of NORBOMIDE, C33H2sN303, also known as, are dispersed in the reaction mixture the names of "Rateate" and "Shoxin" (Merck Index - 10th Edition - N 6527).

EXAMPLE 4
A solid, porous composition for repelling insects is prepared according to Example 1, but the 70 g of tributyl phosphate are replaced by 100 g of dibutyl phthalate which acts as a repellent.

EXAMPLE 5
A solid composition for perfuming the ambient air is prepared by the technique of Example 2, replacing the "PARATHION" with 75 g of a mixture of α and ss-pinenes.

EXAMPLE 6
Insecticide composition with high persistence. The technique of Example 2 is applied to the preparation of a polyurethane foam loaded with insecticide, according to the following weight formula.

Polyols resulting from the addition of propylene oxide
on trimethylol propane
g
OH index 42 .......................... 505
OH index 56 .......................... 126
toluylene diisocyanate .............. 278
water 30.20
ethylene diamine ........................ 1.00
stannous octanoate 0.95
sucrose 12.60 "CYPERMETHRIN", insecticide
cyano (phenoxy-3-phenyl) methyl ester
2,2-dichloro-ethenyl-3-dimethyl-2,2 acid
cyclopropane carboxylic, i.e. C22H1gCl2NO3 52.50
The pores and cells of the product mainly have dimensions ranging from approximately 0.1 to 5 mm and the specific weight approximately 8 g / l.

EXElEPLE 7
15 g of DYCHLORVOS are mixed with 100 g of polyether polyol constituted by polyoxypropylene-polyoxyethylene of molar mass 3500, having an OH number of 57.6. 1.7 g of triethyldiamine dissolved in 5 g of dipropylene glycol and 0.5 g of Sn ++ octoate dissolved in 5 g of dioctyl phthalate are added as catalyst.

 The whole is quickly mixed with 54 g of toluene diisocyanate (TDI) and 6 g of water, while keeping the mixture at room temperature.

 The rigid polyurethane foam obtained has a specific weight of approximately 7.4 g / l; it exerts a very intense insecticidal action.

EXAMPLE 8
Polyurethane foam insecticide wafers are prepared from a diphenylmethane diisocyanate (MDI) of the following composition by weight 55.8% isomer, 2.4, 20% 2.6 isomer of MDI to 2 cores, 7.6% MDI with 3 cores, 4.1% with 4 cores and 12.5 t with 5 cores.

 The polyol used is a copoly-oxyethylene-oxypropylene with an OE / OP molar ratio = 30/70; its molar mass stands out, by weight, at 47% for 4,000, 44% for 600 to 800 and 9% for 200 to 460; it contains 22% water by weight.

 The formulation for polymerization is 1000 g of MDI, 585 g of polyol, 165 g of water, 250 g of PYRIMIPHOS METIL insecticide and 0.05 g of pigment. The mixture is well stirred; the foam is allowed to form in a mold while maintaining its temperature between the ambient and 40 "C. The mold is removed after 1 minute and the product is cut into platelets. It has a specific weight of approximately 7 g / l.

EXAMPLE 9
The procedure is as in Example 8, but the insecticide is replaced by dimethyl phthalate acting as an insect repellant, in particular mosquitoes.

EXAMPLE 10
In a mixture like that of Example 9, the insecticide is replaced by 80 g of ionone which is used to flavor the atmosphere of a room.

EXAMPLE 11
The preparation according to Example 7 is repeated but the DICHLORVOS is replaced by 10 g of DELTRAMETRINE. The rigid foam, with a specific weight of 9.8 is very effective against ants, as well as the destruction of reptiles.

EXAMPLE 12
Application to the destruction of lice.

 In a preparation according to Example 2, instead of Pyrimiphos, 120 g of rotenone previously dispersed in the polyol are used. The polyurethane foam obtained is put in the form of a sheet of about 2 to 3 mm thick, which is fixed on a very thin, very airy fabric. With the fabric-urethane (poly) complex, thus obtained, we make hats or fishnets which are used to style children with lice. After a few hours of keeping these caps on the heads of children, the lice are destroyed. The most practical way is to leave the caps on the heads of children overnight; no danger of intoxication presents itself.

 Similarly, insects are destroyed on animals, especially dogs, cats, monkeys, etc.

EXAMPLE 13
Application to the destruction of flies.

 Two fine mesh cages, each having a capacity of 0.3 m3, with a side opening of 25 cm2, are placed in the window of a stable.

 In each of them, ten pieces of sugar of 5 g are introduced and a plate 100 x 100 x 20 mm of polyurethane foam loaded with insecticide.

(A) - The plate of the first cage is made
with foam prepared according to the example
2, its specific weight being 10 g / l.

(B) - The second cage plate has been
obtained as in example 2, but
with only 73 g of H2O; his weight
specific was 34 g / l.

After 24 hours, the following numbers of dead flies were found
46 in cage A,
21 in cage B, which shows the higher activity of the product according to the invention (A).

EXAMPLE 14
Near a pond, under shelters, in summer, two cages were made of fine mesh, like those of Example 13.

In each one was placed bait in the form of trash and a polyurethane foam plate, containing insecticide.

(C) - In the first cage, the plate was
foam of Example 8 (specific weight
7 g / l)
(D) - in the second cage, it contained the
same constituents but had a
specific weight of 22 g / l.

 After 24 hours, dead insects were found at the following numbers: in (C) 63, in (D) 38.

EXAMPLE 15
Determination of the quantities of active substance released into the atmosphere at room temperature in 24 hours.

Two plates of 100 x 100 x 20 mm of polyurethane foam according to Example 8 with PYRIMIPHOS METIL are left in a room of 30 m3, at 20au, for 24 hours. By weighing before and after this time, we determine the quantities of insecticide that have spread in the platelets
(E) - foam of 7 g / l specific weight
100 mg
(F) - 15 g / l specific weight foam
25 mg.

Claims (10)

1. Product consisting of a polymer foam, containing an active substance, releasable in the ambient medium, characterized in that the foam has a specific weight of approximately 5 g / l to 20 g / l. 2. Product according to claim 1, whose specific weight is from 6 to 15 g / l. 3. Product according to claim 1 or 2, characterized in that, in the foam, open pores, more than 0.2 mm in diameter represent at least 10% of the total pores. 4. Product according to claim 3, in which the major part of the pores have diameters of 0.6 to 6 mm. 5. Product according to one of the preceding claims, in which the foam is made of polyurethane. 6. Product according to one of the preceding claims, characterized in that its active substance content is approximately 0.5 to -20% by weight. 7. Product according to one of the preceding claims, characterized in that the active substance or substances are bactericides, insecticides, raticides, antilimaces or other gastropodocides or mollusquicides, repellents or attractants of insects or other animals, or odorants or deodorants . 8. A method of preparing a product according to one of the preceding claims, which comprises incorporating an active substance into a plastic material, characterized in that said substance is dispersed in a prepolymer or a polymerizable mixture, which one polymerizes in the form of solid foam, more or less rigid or flexible, with a specific weight of 5 g / l to 20 g / l. 9. Method according to claim 7, characterized in that a pigment or dye is added to the mixture which discolours substantially with the same speed with which the composition is used up in the active substance in the open air. 10. Method according to claim 7 or 8, characterized in that the polymerization is carried out at a temperature not exceeding 100 "C, preferably between 0 and 60" C, in particular the polymer to be formed being polystyrene, polacrylate, polymethacrylate , polycarbonate or polyurethane.