IL31238A - Shaped articles with long-term vapour emission containing phosphorus compounds as active agents - Google Patents

Description

31238/2 Shaped articles with long-term Vapour emission containing phosphorus compound as active agents FARBENFABRIKM BAYER AKTI GBSEI.LSCHAFT CJ29467 The present invention- relates to shaped articles containing 0,0-dimethyl-0-( 2 , 2-dichlorovinyl)-phosphoric acid esters, unsaturated polyesters and' vinyl compounds copolymerisable therewith, having a long term vapour emission. These shaped articles possess the property of giving off the active compound, hereinafter briefly called DDVP, to the surrounding atmosphere for a.. long time, for example, several months, in an insecticidally and acaricidally effective amount.

DDVP of the structural formula . 0 ^O-C^CCl GH^ - cr H has long, been known as a pesticidally active compound with insecticidal and acaricidal effects (G. Schrader: "Die Entwicklung neuer insektizider Phosphorsaureester" , 3rd edition, Verlag Chemie Weinheim, Bergstraese [1963] ) . Like most insecticides, DDVP acts as a contact as wel as a stomach and respiratory poison.

Since the compound possesses even at room temperature a high vapour pressure. (20°Cil.2xlO"2 mm Hg) in comparison wit other insecticides, its. effect as a respiratory poison is particularly note-worthy. The compound is therefore used in automatic spraying devices as an aerosol for the control of noxious insects and spiders.

Advantageous for this purpose though its high volatility is, it hinders the attainment of an adequate lasting effect. The DDVP volatilises and disperses from a room so rapidly that the room' can, only 1 to 2 hours after application of the active compound, be again infeeted with vermin without the latter being killed. A further disadvantage of DDVP lies in that it hydrolyses comparatively rapidly and this, impaire its lasting effect as a respiratory poison. the evaporation of DDVP in a room so that it takes place quit gradually to maintain a concentration which is pesticidally effective hut non-toxic to humans, and simultaneously to protedr the active compound against hydrolytic decomposition.7 In regard to such attempts, German Auslegeschrift 1,207,144, column 1, lines 20 to 24» reads: "The production of long-lasting preparations is difficult, not only because of the high sensitivity to moisture of DDVP but also because of its incompatibility with many carrier substaicesM. In the aforesaid specification it is further disclosed that. the problem of long-lasting, uniform insecticidal effect cannot be solved with the aid of mixtures of DDVP and montah wax alone ; since no appreciable vaporisation or evaporation of the active compound occurs. Even after 4 weeks' storage; at room temperature, the content of active compound of such mixtures is practically ' the same, so that they . cannot be used for the purpose aimed at. Hence German Auslegeschrift 1,207,144 claims volatile agents having a long-lasting insecticidal effect which consist of a combination of DDVP as active compound, a montan wax and hydro- genated cottonseed oil or dibutylphthalate* These formulations, however, have the disadvantage that they exude a mixture of DDVP and plasticiser which gives rise to toxicological problems.

An attempt has been made to soak natural products with DDVP. British Patent Specification 1,072,218 claims a carrier for DDVP consisting of wood with a moisture content of less than 8$. The disadvantages of such a mode of application are obvious; natural products are never homogeneous in their structure. This is part- icularly true of a material with such a varying structure as wood. The differences between sapwood and heartwoOd and the structure of spring wood laminae and summer wood laminae are onl ' two examples of this. Prom type to type, and even within one type to the environmental conditions under which a tree has grown.

The expert -knows how differently different pieces of wood behave when impregnated, one piece practically never resemblin the other. To achieve.a uniform evaporation of the active com-pound an individual dosage would therefore have to be worked out for each piece of wood.

The same considerations apply also in regard to a product on the market in which cuttlefish shell is used as carrier material for DDVP. This skeletal element of the cuttlefish, of which likewise no piece is ,the* same as another, suffers from the further disadvantage that it is not everywhere readily available in any; desired amount. Natural products are therefore most unsuitable for the solution of the problem.

. Furthermore, in German Auslegeschrift 1,230,259, shaped articles with persistant insecticidal effect are described which are characterised by the combination of a volatile, insecticidally effective organic phosphorus compound of specific composition and a thermoplastic, water-insoluble macromolecular substance, in particular polyvinyl chloride or copolymers which contain vinyl chloride. . ' ■■ '< As disclosed in the above Auslegeschrift, the absorbency of polyvinyl chloride for DDVP is limited, despite certain plast-icising properties of the phosphoric acid ester on. the synthetic material. Thus, for example mixtures of. powdered polyvinyl chloride which contain 25% DDVP, are wet (see column '5, line 65 of German Auslegeschrift 1,230,259).

, On the other hand, experiments showed that formulations of polyvinyl chloride and DDVP alone are not suitable as vaporising agents, since,1 even, after only a short, time, they cease to give off sufficient active compound. To such mixtures, therefore, formulations described in German , have to be added. The dependence of the effect of DDVP-containing polyyinyl chloride formulations on the plasticiaer content can be seen from the following Table 1 which relates to the duration of activity in respect of house flies ( usca domestica) of shaped articles of polyvinyl chloride containing 20 DDVT (size: 12x12.5 x0.5 cm) in relation to their plasticiser content, measured in a room of 50 cubic metres* size.

Table 1.

Plasticiser Duration in weeks of activity such that (dioctylphthalate) 0% of the flies were killed within 24 content in % hours 2 4 10 As the above Table shows, considerable amounts of plasticiser are necessary for the shaped articles tested to have a. sufficiently long-lasting insecticidal activity as solid vaporising, agents. If the plasticiser is lacking, or if not enough of it is present, the surface of the shaped article very rapidly becomes impov-erished in active compound. Not enough DDVP migrates from the interior of the shaped article, so that it quickly becomes ineffective.

If, therefore, on the one hand the addition of considerable amounts of plasticiser is necessary, there results on the other hand the difficulty that this addition must take place. at the expense of the content of active compound. A formulation containing; relatively large quantities of plasticiser and DDVP may have undesirable structural properties. Thus, for example shaped articles of polyvinyl chloride which contain 20% plasticiser and 18% DDVP exude during storage in gas-tight packs and also in ractical use considerable amounts of a mixture of plasticisex. and the toxicological considerations connected therewith, this behaviour is very disadvantageous. Since polyvinyl chloride, on the other hand, is capable of absorbing only limited amounts of DDVP and plasticiser, this disadvantage would be overcome only by reducing in the formulatiohs either the proportion of active compound or the proportion of plasticiser, or both at the same time. · A lessening of the DDVP content would, however, impair the activity and a reduction of the proportion of plasticiser would affect adversely the diffusion of the active compound and thus also the effectiveness* For this reason, for shaped articles which consist of polyvinyl chloride, DDVP and plasticiser, it is recommended that in use they be accommodated in a cardboard frame which is to receive the dripping mixture of active compound and plasticiser.

A further disadvantage of the DDVP- polyvinyl chloride formulations must be seen in that, even when they contain the maximum of 20% plasticiser, a considerable part of the active compound does not reach the surface and is therefore wasted. Such shaped articles which have been used for 16 weeks under practical conditions' and no longer possess a satisfactory biological activity still contain, by chemical analysis (infra-red measurement after extraction), about 50 to 60% of their original DDVP content* This method of application therefore appears very uneconomic.

Finally, it, must, also be taken into account that, for the production of shaped articles of polyvinyl chloride, plasticiser and DDVP a considerable expenditure in terms of equipment is necessary because the mixture has to be extruded which pre-supposes the presence of suitable machinery. Moreover, since production takes place at high temperatures (170 to 180°C), losses of active compound occur which necessitate extensive protective measures for the operatives engaged in the manufacture. water-insoluble macromolecular. substances are claimed as carrier materials, particular examples being: polymeric vinyl compounds, polyolefins, polyacrylates, pOlyvinylacetals, polyvinylidene compounds, synthetic and natural elastomers, for example rubber and cellulosic synthetic materials. Examples of preferred vinyl compounds are polyvinyl halides, such as polyvinyl chloride and fluoride, polyacrylate esters and polymethacrylate esters, for example polymethylacrylate and polymethylmethacrylate; polymeric benzene compounds, such as polystyrene and polymerised vinyltoluene. The polymers or copolymers of vinyl chloride are said to be particularly suitable and they allegedly exhibit , besides good physical properties, a very good compatibility with the insect-icidal organic phosphorus compounds to be used.

In addition it is expressly emphasised in the said Ausleg-eschrift that only with the use of a non-crosslinked material, that is, a thermoplastic material, is the desired effect achieved, namely the active compound is given off into the atmosphere in controlled amounts continuously and uniformly for months.

From Swiss Patent Specification 289,915, too, it is learned that hardened shaped articles with active compound worked into them, for example hardened products of phenolformaldelyde resins, soon stop exhibiting any useful insecticidally active vaporisation. For one skilled in the art, the impression that such thermosetting plastics are wholly unsuitable for such formulations had to result.

These results published in the technical literature were confirmed by our own experiments, since it was hot possible to attain, by the incorporation of DDYP into unsaturated polyester resins, a long-lasting insecticidally activite vapour phase in shaped articles. The surface of such articles very rapidly becomes impoverished in active compound and, because of the cage effect of the three-dimensionally crosslinked thermosetting the deeper layers. The result of this is that the shaped articles so produced possess no satisfactory effect. Shaped articles as used herein comprise shaped bodies such as plates, spheres, strips, tablets or bars or any geometric solid (including hollow bodies).

It has now been. ound that shaped articles, such as plates, spheres, strips, tablets or bars based on 0,0-dimethyl-0-(2,2-di-chlorovinyl)-phosphoric acid ester, unsaturated polyesters and vinyl compounds copolymerisable therewith have a long term pesticidal vapour emission effect when the shaped articles contain solid fillers, optionally in combination with liquid fillers, and the weight ratio of active compound to unsaturated polyester is 1:4 to 2:1.

Furthermore, the shaped articles have considerable advantages over the formulations described in the literature based on thermoplastic compositions.

The invention also provides a process for the production of shaped articles having a long term pesticidal Vapour emission effect in which a mixture of 0,O-dimethyl-0-( 2, 2-dichlorovinyl)-phosphoric acid ester, as active compound and an unsaturated polyester is copolymerised with a vinyl compound, the copolymer containing one or more solid fillers, the weight ratio of active compound to unsaturated polyester being from 1:4 to 2:1.

Suitable solid fillers to be used according to the invention are, for example: fibres of glass, sisal, hemp, nettles, coconut, flax and other vegetable products or synthetic fibres. Further examples of solid fillers are those of mineral nature, for example titanium dioxide, iron oxides, kaolin, quartz and other inert materials.

Suitable liquid fillers are those with carrier effect, for example dipctylphthalate, chloroparaffin or alkylsulphonic acid aryl ester.

The amount of the fillers-must, as already said, be such that the weight ratio of DDVP to thermosetting plastic is 1:4 to 2:1, preferably 1:3 to 1:1.

It has been shown that thermosetting plastics in the aforesaid form, in particular unsaturated polyester resins, possess the following advantages over thermoplastic compositions: 1. They have a better absorbency, for DDVP (up to 50 ); 2. Since they retain less active compound, there results a better quantitative utilisation of the latter; 3. They possess a better activity; 4. The shaped articles according to the invention do not drip; . The productio of the shaped articles can take place at room temperature; 6. The production is possible by pouring into simple moulds consisting of any desired material, for example wood, without the use of machines; 7. The. method of production according to the invention renders possible a structure of the shaped articles of layers with different DDVP and filler content.

For the production of the formulations according to the invention, mixtures of unsaturated polyester resins and DDVP are hardened according to methods customary for the processing of unsaturated polyester resins, with the aid of polymerisation-initiating radicals (see for example "I. Bjorksten et al: Polyesters and their Application," Reinhold Publishing Corporation, New York, 1956).. Since losses of the readily volatile active compound may occur at higher temperatures, it is advantageous to use initiator-accelerator systems effective even at room temperature, or high-energy rays such as ultra-violet or electron beams, for the production of the polymerisation-initiating radicals. Of the initiator-accelerator systems effective at room temperature, the peroxide and a dialkylamine, for example dimethylaniline , or a, ketone peroxide such as methylethyl ketone peroxide or cyclo- hexanone peroxide and a cobalt accelerator, such as cobalt naph- thenate, resinate, octoate or acetylacetonate, can be used, but in the presence of DDVP a distinctly reduced speed of hardening ' is. observed. Oh the other hand, initiator-accelerator systems consisting of a soluble vanadium compound, for example the vanadium salt of a partial phosphoric acid ester or. vanadyl-p-tol-uensesulphonate with peroxides attractive thereto, for example per-esters, per-ketals, or alkyl-hydroperoxides, preferably cum- ene hydroperoxide, retain practically all of their effectiveness in the presence of DDVP and are therefore preferably used.

An advantageous form of application is also the working in of the DDVP into polyester foams which for example, may be produced according to the methods described in German Patent Specifications l.¾¾¾04¾. (Application F49 750 IVc/39b) and Κ'Φ θβ.9. (Application P49 752 IVc/39b) . The hardening products on which the shaped articles of synthetic materials are based are the usual mixtures of unsaturated polyesters and monomeric vinyl compounds capable of being added thereto by polymerisation, in the ratio of 20:80 to 90:10 per cent by weight. The unsaturated polyesters are prepared in known manner by polycondensation of polyhydric, in particular dihydric, alcohols such as 1,2-propane-diol, 1, 3-butanediol or 2,2-dimethyl-l,3-propanediol or polycondensation of, di-or tri- ethyleneglycol with α, $-unsaturated di-carboxylic acids or anhydrides thereof, for example, fumaric acid or maleic anhydride, optionally with addition of saturated di-carboxylic acids such as phthalic acid or its anhydride, iso-phthalic, succinic, adipic or sebacic acid. Monomers which can be added by polymerisation are, for example styrene, mono- and di-chiorbstyrene, divinylbenzene.,A^¾nyltoluerie; vinyl esters such as phthalic acid diallyl est.er and triallyl phosphate. Inhibitors which may be optionally concurrently used, are for example : quinone hydroquinone , toluenehydroquinone , 2 , 5-di-tert .-butylquinone or 2 , 6-di-tert-.butyl-p-cresol.

Further suitable thermosetting plastics are, for example, resins based on diisocyanate-modified polyethers or polyesters', epoxides, phenol-formaldehyde and urea- or melamine-formaldehyde.

The shaped articles according to the invention can by reason of their pesticidal activity be used for the control of the most diverse types of pests, such as insects and spiders.

The invention also provides a method of combating insect or arachrid (including acarids and spiders) pests in a confined space (such as a room or cupboard) which comprises locating in the confined space a shaped article according to the invention which · emits a pesticidal vapour.

The following Examples illustrate the invention, "parts" meaning parts by weight.

Example 1.

Into a mixture of 1935 parts of polyester resin A(see below) and 774 parts DDVP are stirred successively 90 parts of a 0^ solution of methylethylketone peroxide in dimethylphthalate and 30 parts' of a cobalt octoate solution in dioctylphthalate which contains 1 per cent by weight of cobalt . From this mixture- there is ; prepared in a closed mould a 5 mm thick moulded plate with a glass conteiit of about 30 per cent by weight, using a glass fibre mat of 450 g weight per square metre. The plate is released from the mould after 2 hours and then cut into shaped articles of the size 12x12 cm. The test articles possess a dry and non-tacky surface. Example 2. ·. 1533 parts of unsaturated polyester resin B (see below) are ' intimately mixed with 851 parts DDVP, 596 parts, dioctylphthalate, methylphthalate and 30 parts of a cobalt octoate solution in di-octylphthalate which contains 1% cobalt. Using a glass fibre plate of density 450 g/m , there is prepared from this mixture in a closed mould a 5 mm thick moulded plate with a glass content of about 30 per cent by weight. After 24 hours, the plate with non-tacky, dry surface is taken out of the mould and cut into test pieces of the dimensions 12x12 cm.

Example 2(a) (Comparative test) i 800 parts of the unsaturated polyester resin A (for preparation, see below), and 200 parts DDVP are well mixed. The mixture is then catalysed with 30 parts of a 40 solution of methyl-ethylketo peroxide in dimethylphthalate and 10. parts of a cobalt . octoate solution in dioctylphthalate which contains 1% cobalt, and from this mixture a 5 mm thick moulded plate is produced in a closed mould. After 24 hours the plate is released from the mould and cut into test pieces of the dimensions 12x12 cm which feel dry to the touch.

Example 3 A plate produced according to Example 2(a) (comparative test) as well as, in each case, one of the plates obtained according to Examples 1 and 2 are suspended individually in the middle of rooms of equal size of 50 cubic metres volume and, in each case, 2000 house flies (Musca domestica) were exposed to it. It is observed whether all the flies have been killed in the course of 24 hours. The tests are repeated at an interval of one week in each case until a 100 destruction of the flies within 24 hours is no longer observed. The lasting effect ..of the plate resulting therefrom can be seen from the . following Table 2: Table 2 Shaped articles according to Example Duration of activity in weeks Example 4 Into a mixture of 225 parts of polyester resin A (for preparation, see below) and 75 oarts DDVP are stirred successively 9 parts of a 0$ solution of methylethylketone peroxide in dimeth-ylphthalate, and 3 parts of a cobalt octoate solution in dl-octylphthalate which contains 1 cobalt. Prom this mixture there is produced in a closed mould, with the use of a glass fibre mat of 450 g weight per square metre, a 5 mm thick moulded plate with a glass content of about 30 per cent by weight. The plate, the surface of which is free from tackiness, is released from the mould after 2 hours, then tempered at 4Q°0 for hours in a gas-tight container and cut into shaped articles of the size 12x12 cm. Example 5 66.5 parts polyester resin B (for preparation, see below) and 3.5 parts DDVP are intimately mixed with 1.75 parts of a 40$ solution of methylethylketone peroxide in dimethylphthalate and 0.7 · parts of a cobalt octoate solution in dioctylphthalate which contains 1 per cent by weight cobalt. Prom the mixture obtained there is produced, using a glass fibre mat of 450g weight per square metre, a 1 mm thick moulded plate with a glass content of about 30 per cent .by weight. After slight gelling, there is laminated onto both sides of this moulded plate, a further 1 mm thick plate which likewise contains about 30 per cent by weight of glass fibre mat, but 10 per cent by weight DD7P. Finally, after slight gelling of these layers, there is again applied to the upper and lower surface in each case a further 1 mm thick layer with a DDVP content of 50 and a glass fibre mat content of about 30 per cent by weight and the external surfaces of the test piece are covered with cellophane film. After hardening and removal of the film, the surface of the shaped article is free from tackiness and dry.

Example 6 are individually suspended in the middle of rooms of equal size of 50 cubic metres volume and exposed in the latter to, in each case, 1000 house flies (Musca domestica). It is then observed in what time 50$ of the flies have been killed (LT^Q). At specific intervals of time, which can be seen from the following Table 3» flies are again released in the test rooms and the tests are evaluated in the same manner as previously. Between the individual experiments the rooms are aired adequately.

Table 3 ·.' PreOaration Occurrence of LTCQ in the case of Musca according to domestica (in hours).

Example weeks after the hanging up of the shaped articles 0 1 4 6 10 4 1 2 2 2,5 3 1,5 2 3 3,5 5 .

Example 7 45 parts of unsaturated polyester resin A (for preparation,-see below) and 25 parts DDVP are very well mixed with 30 parts barium sulphate, 2.1 Oarts of a 40$ solution of methylethylketone peroxide in dimethylphthalate and 0.7 parts of a cobalt octoate solution in dioctylphthalate which contains Ifo cobalt. The mixture is poured into a mould which consists of 2 glass plates of the dimensions 20x20x0.3 cm which internally are kept at a distance of 5 mm by a plastic tube. After 24 hours, the moulded plate is released. The surface of the shaped article is free from tackiness and. dry.

Example 8 45 parts of unsaturated polyester resin A (for preparation, see below) and 25 parts DDVP are ground with 30 parts of most fin-ely ground, readily dispersible rutile, 0.7 parts cumene hydroperoxide and 0.7 parts of an accelerator solution which contains 1 per cent by weight of vanadium. The mixture is hardened at from tackiness and dry is obtained. i Example 9 225 parts of polyester resin 0 (for preparation, see below), 12 parts DDVP, 1.7 parts cumene hydroperoxide and 2.0 parts of an accelerator solution which contains 1$ vanadium are intimately mixed. Prom this mixture there is produced in a closed wooden mould, with the use of glass staple fibres of 6 mm length* a 5 mm' thick moulded plate with a glass content of about 30 per cent by weight.. The plate is released after 2 hours with non-tacky and dry surface.

Example 10 80 parts of polyester resin G (for preparation, see below) are intimately mixed with 20 parts chloroparaffin (70 per cent by weight chlorine),.40 parts DDVP, 1.4 parts cumene hydroperoxide and 1.4 parts accelerator solution which contains 1%.vanadium.

Using a glass fibre mat of surface density 450 g per square metre there is produced in a closed wooden mould a 5 mm thick moulded plate with a glass content of about 30.per cent by weight and the plate is removed from the mould after 24 hours with surface free from tackiness and dry. During suspension for three months in a closed room, no drip formation. is observed.

Example 11 A plate produced according to Example 2 as well as one consisting of polyvinyl chloride which contains 20$ plasticiser and 18$ DDVP are freely suspended for 16 weeks in a room and the DDVP content' is then determined analytically (infra-red method after extraction). The plate according to Example 2 has given off to the atmosphere 71#> the comparative plate of polyvinyl chloride has given off only 35.5# of its original DDVP content.

The unsaturated polyester reeins used as starting substances may be prepared in the followin manner. parts maleic anhydride, 43 883 parte phthalic anhydride, 29 267 parte, 1, 2-propanediol and 4.2 parts hydroquinone is dissolved in 28 000 parts styrene .

Resin B: The unsaturated polyester is prepared from 647 parte maleic anhydride, 2 284 parts phthalic anhydride, 1 276 parts 1, 2-propanediol, 724 parts dipropyleneglycol and 0,125 parts hydroquinone. After an acid number of 35 ie reached," the product is dissolved in 1510 parts styrene.

Resin C: A polyester of an acid number of 31 prepared from 1294 parts maleic anhydride, 1598 parts phthalic anhydride, .986 parts 1, 2-propanediol, 374 parts glycol, 636 parts diglycol and 0.72 parts hydroquinone is dissolved in 1910 parts styrene.

Claims (11)

1. What we claim is:- 1. Shaped articles having a long term pesticidal vapour emission effect containing 0,0-dimethyl-0-(2,2-dichlorovinyl)^ phosphoric acid ester as active compound, an unsaturated polyester and a vinyl compound copolymerisable therewith in admixture with one or more solid fillers, the weight ratio of active compound to unsaturated polyester being from 1:4 to 2:1.

2. · Shaped articles according to claim 1 containing a liquid filler in admixture with.the. solid filler.

3. Shaped articles according to claim 1 or 2 in which the weight ratio of active compound to unsaturated polyester resins is from 1:3 to 1:1.

4. · Shaped articles according to any of the preceding claims in which the unsaturated polyester resin is one of those hereinbefore mentioned,

5. · Shaped articles according to any of the preceding claims in which the vinyl compound is one of those hereinbefore mentioned.

6. Shaped articles substantially as described herein, and with reference to Examples 1,2,4,5,7,8, 9 and 10. .

7. · A process for the production of shaped articles having a long term pesticidal vapour emission effect in which a mixture of 0,0-dimethyl-0-(2,2-dichlorovinyl)-phosphoric acid ester as active compound and an unsaturated polyester is copolymerised with a vinyl compound, the copolymer containing rie or more solid fillers, the weight ratio of active compound to unsaturated polyester being from 1:4 to 2:1.

8. A process according to claim 7 in which the copolymer contains a liquid filler in admixture with the solid filler.

9. · A process according to claim 7 or 8 in which the ratio to 90:10 per cent by weight.

10. A process according to any of claims 7 to 9 in which the polymerisation is carried out at room temperature using a suitable initiator-accelerator system or a high energy ray.

11. A process for the production of shaped articles having a long term pesticidal vapour emission effect substantially as described herein, and with reference to Examples 1,2,4,5,7,8, 9 and 10. 12· Shaped articles having a long term pesticidal vapour emission effect prepared by a process according to any of claims 7 to 11. 13· A method of combating insect or arachnid pests in a confined space which comprises locating in the space a shaped article according to any of claims 1 to. 6 or 12 which emits a pesticidal vapour. Le A 11 226-E -18-