Classifications

• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
  • A01N25/18—Vapour or smoke emitting compositions with delayed or sustained release
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N53/00—Biocides, pest repellants or attractants, or plant growth regulators containing cyclopropane carboxylic acids or derivatives thereof

Definitions

• the present invention relates to a sustained-release insect repellent sheet.
• insect repellents insecticides, repellents, and other insect repellents have been used to prevent small animals, insects, and other pests from invading a variety of objects, including buildings and fixtures such as houses and stores, installed equipment such as vending machines, and containers such as grain bags and rice bins.
• Pyrethroid-based chemicals are commonly used as these insect repellents, and are used, for example, by placing them in a sprayer and spraying them.
• spraying insect repellents they easily wash away, making it difficult to maintain their effectiveness over the long term.
• spraying insect repellents may pollute the surrounding environment.
• Patent Document 1 describes a sustained-release sheet in which a resin composition containing a filler is stretched to create voids around the filler, and these voids are filled with a functional liquid ingredient such as an insecticide. This sustained-release sheet is able to release the liquid ingredient over a long period of time while maintaining a constant release amount.
• the voids In the sustained-release sheet of Patent Document 1, in order to allow a larger amount of liquid ingredient to be contained in the voids formed around the filler by stretching, the voids must be open, otherwise the liquid ingredient will not penetrate all the way to the inside of the sheet. To open the voids, a large amount of filler must be added and the sheet must be stretched at a high stretch ratio. As a result, in addition to restrictions on the stretch ratio and the amount of filler added, there are also natural limitations on the sheet thickness, making it difficult to change the amount of liquid ingredient contained within the sheet under these conditions. As a result, the effect lasts for an unnecessarily long time, and the addition of large amounts of insect repellents, etc. leads to increased costs.
• the purpose of the present invention is to make it easier to adjust the amount of insect repellent and other ingredients contained when applying such a sustained-release sheet to an insect repellent sheet, thereby making it easier to adjust the release period.
• a sustained-release insect repellent sheet that is made by dispersing a filler in a thermoplastic resin and carrying a liquid component in voids formed around the filler, where the voids are interconnected and the carried liquid component contains a pyrethroid-based drug as an active ingredient, as well as a surfactant and/or liquid paraffin.
• the pyrethroid agent is preferably transfluthrin, in which case it preferably contains a fatty acid ester as a surfactant.
• a sustained-release insect repellent sheet that solves the above-mentioned problems is a method for producing a liquid-component-containing sheet by stretching an unstretched sheet of thermoplastic resin with a filler dispersed therein, and then loading a liquid component into the voids formed around the filler.
• the liquid component contains a pyrethroid drug as an active ingredient.
• the sustained-release insect repellent sheet may be produced by impregnating the unstretched sheet with a mixed liquid obtained by mixing a readily volatile component with the liquid component during or after stretching, loading the mixed liquid into the voids, and then performing a heat-relaxing treatment while volatilizing the readily volatile component.
• the release period can be easily adjusted, making it possible to provide a sustained-release insect repellent sheet suited to the intended use.
• 3A and 3B are schematic cross-sectional views of unstretched films according to comparative examples and examples.
• 3A and 3B are schematic cross-sectional views of stretched sheets according to comparative examples and examples.
• the crystallinity is too high, the medicinal ingredient of the liquid component may not be able to pass through the thermoplastic resin, resulting in an excessively low release rate.
• polyolefins with low crystallinity such as low-density polyethylene and low stereoregular polypropylene, are preferred.
• low-density polyethylene the lower the density, the lower the crystallinity tends to be, and it is preferable to use one with a density of 0.895 to 0.925 g/ cm3 .
• the low-density polyethylene is preferably linear low-density polyethylene.
• the melting point of the low-density polyethylene is preferably 80 to 135°C.
• the softening point of the low-density polyethylene is preferably 45 to 90°C.
• branched low-density polyethylene tends to be less likely to crystallize, and from the viewpoint of gradually releasing the liquid component contained within the sheet, it is also preferable to mix branched low-density polyethylene to a degree that does not impair stretchability in order to further reduce crystallinity.
• the partial inclusion of branched low-density polyethylene also tends to make it easier to create voids between the filler and the sheet, making it easier to obtain interconnected pores.
• the filler is primarily an inorganic filler, such as calcium carbonate, talc, silica, mica, zinc oxide, barium sulfate, titanium oxide, or aluminum.
• organic fillers may also be used as long as they are incompatible with the thermoplastic resin used to make the sheet and exhibit rigid properties at room temperature. Numerous voids are formed around the filler, particularly through stretching, and liquid components are supported within these voids. Fillers that are resistant to liquid components are preferred, with inorganic fillers being relatively stable. Filler shapes that are closer to spherical facilitate dispersion and facilitate uniform void size. For this reason, calcium carbonate is preferred.
• the particle size of the filler used here is not particularly limited and can be selected appropriately depending on the sheet thickness and the state of interconnected pores.
• an average particle diameter of 0.1 to 10.0 ⁇ m as measured by air permeability testing is preferred.
• the average particle diameter can be calculated from the specific surface area measured by the Blaine air permeability test. Dispersing more fillers with smaller average particle sizes will allow the liquid component to be released for a longer period at a given volatilization rate, but if the average particle size is too small, the voids will also become smaller, making it difficult to support the liquid component due to the effects of surface tension, etc. From the perspective of supporting liquid components containing surfactants and liquid paraffin together with pyrethroid agents, it is more preferable that the average particle size be in the range of 0.5 to 3 ⁇ m.
• the force that attracts the liquid component is generated by deforming the unstretched sheet, and when increasing the suction force by stretching, it is preferable to increase the stretching ratio.
• Interconnection of voids is also generated by deforming the unstretched sheet, and can be achieved by stretching at a relatively high stretching ratio. If the voids are not interconnected, the liquid component will not penetrate to the interior of the sheet. For this reason, it is preferable to stretch the unstretched sheet at a stretching ratio of 3 or more. On the other hand, if the stretching ratio is too high, the sheet will be more likely to break during production, and if the voids become too large due to stretching, the sustained-release properties may be impaired. Therefore, a stretching ratio of 10 or less is preferable.
• the liquid ingredient contained in the liquid ingredient-containing sheet uses a pyrethroid-based pesticide as its active ingredient.
• Pyrethroid-based pesticides are effective in controlling pests, and examples include metofluthrin, transfluthrin, profluthrin, empenthrin, cyfluthrin, fenothrin, cyphenothrin, permethrin, tralomethrin, fenpropathrin, and etofenprox. These may be used alone or in combination in the present invention.
• a room-temperature volatile compound having a vapor pressure of 1 ⁇ 10 ⁇ 4 to 1 ⁇ 10 ⁇ 2 Pa at 30° C.
• room-temperature volatile pyrethroid compounds include metofluthrin, transfluthrin, profluthrin, and empenthrin.
• the liquid components contain surfactants and/or liquid paraffin.
• the surfactants and liquid paraffin act as extenders to dilute the pyrethroids in the liquid components, and adjusting the pyrethroid content in the liquid components makes it possible to adjust the volatilization rate and shelf life of the final insect repellent sheet.
• surfactants and liquid paraffin do not increase the surface tension of the liquid components as a whole, making it easier for the liquid components to spread throughout the minute voids formed in the sheet.
• surfactants and liquid paraffins that are virtually non-volatile at room temperature are preferred.
• fatty acid esters include diisobutyl adipate, diethylhexyl succinate, cetyl 2-ethylhexanoate, glyceryl tri-2-ethylhexanoate, hexyldecyl ethylhexanoate, triethylhexanoin, neopentyl glycol diethylhexanoate, trimethylolpropane triethylhexanoate, pentaerythrityl tetraethylhexanoate, neopentyl glycol dicaprate, ethylhexyl isononanoate, isononyl isononanoate, isodecyl isononanoate, isotridecyl isononanoate, he
• transfluthrin examples include isocetyl palmitate, isopropyl palmitate, ethylhexyl palmitate, octyl palmitate, ethyl stearate, octyl stearate, isocetyl stearate, ethyl isostearate, isopropyl isostearate, hexyldecyl isostearate, isostearyl isostearate, glyceryl triisostearate, polyglyceryl triisostearate, trimethylolpropane triisostearate, pentaerythrityl tetraisostearate, ethyl oleate, caprylic/capric triglyceride, and octyldodecyl 12-stearoyl stearate.
• Transfluthrin has a melting point of approximately 33°C and exists in a mixture of solid and liquid forms at room temperature.
• a liquid-component-containing sheet is obtained by stretching while exposed to a liquid component, the stretching bath is heated, so transfluthrin remains in a liquid state.
• the liquid-component-containing sheet solidifies at room temperature.
• the texture, hardness, and other properties of the liquid-containing sheet change at room temperature, and the solidification can clog or deform the pores, making it more likely to change volatility.
• transfluthrin By thoroughly mixing transfluthrin with fatty acid esters, its crystallization can be adjusted, allowing it to remain in a liquid state even when used at room temperature.
• liquid paraffin contains a large amount of olefin hydrocarbons
• thermoplastic resin forming the sheet is polyolefin
• liquid components containing liquid paraffin have a good affinity with the sheet, making it easier for the liquid component to penetrate into the voids. Therefore, unless there are special circumstances such as the aforementioned transfluthrin, it is preferable to add liquid paraffin to the liquid component, and surfactants and liquid paraffin may be mixed together as long as it does not affect dispersion.
• the blending ratio (mass ratio) of pyrethroid agent to surfactant and/or liquid paraffin in the liquid component is selected appropriately, taking into consideration the target effective period, etc. If a longer effective period is desired, a higher blending ratio of pyrethroid agent is preferable.
• a mass ratio of transfluthrin:surfactant 1:0.1-10.
• the liquid component content in the liquid component-containing sheet can be selected as appropriate, but it is preferable that the liquid component content be 10 to 60% by mass. Because the pyrethroid content can be adjusted using surfactants or liquid paraffin, there is no need to reduce the liquid component content itself when reducing the pyrethroid content; production conditions that ensure sufficient voids in the sheet can be maintained. Increasing the liquid component content requires forming a large number of voids. Therefore, increasing the liquid component content too much not only reduces the strength of the sheet, but also makes the void shape unstable and makes it difficult to ensure sustained release.
• a volatile component that is more volatile than the medicinal component may be mixed with the liquid component.
• the volatile component referred to here is a component that is liquid at room temperature, and particularly one that is easily volatile and has a vapor pressure of 1 x 102 Pa or more at 30°C.
• the volatility is too high, it is difficult to handle as a liquid, so it is preferable that the vapor pressure at 30°C is 1 x 105 Pa or less.
• Specific examples include n-hexane, toluene, o-xylene, etc., and those that are easily mixed with the liquid components, pyrethroid drugs, surfactants, and liquid paraffin, and have low reactivity with these are preferred, and n-hexane is more preferred among them.
• both the liquid component and the readily volatile component are retained in the voids.
• the readily volatile component quickly evaporates.
• a force is generated that draws the liquid component into the voids, filling the space previously occupied by the readily volatile component. This force can be used to draw the liquid component that seeps out onto the sheet surface due to sheet shrinkage back into the voids.
• a sheet is subjected to a heat-relaxing (annealing) treatment immediately after being stretched in the liquid component, in which heat is applied to the sheet to force it to shrink, the liquid component will seep out onto the sheet surface.
• heat-relaxing treatment can also suppress sheet shrinkage over time, preventing deformation and seepage of the liquid component even during use of the insect repellent sheet.
• thermoplastic resin of the sheet is polyolefin and n-hexane is used as the volatile component
• n-hexane is compatible with polyolefin and penetrates to some extent into small voids formed by stretching. If even a small amount of the mixture of liquid component and n-hexane penetrates the voids, the evaporation of n-hexane generates a force that draws the liquid component into the voids. Therefore, even without stretching in a mixture of liquid component and volatile component, it is possible to support the liquid component in the voids formed around the filler by applying a mixture of liquid component and n-hexane to a sheet that already has voids formed around the filler.
• the liquid component can inhibit adhesion between the layers, resulting in insufficient adhesion and the risk of the liquid component volatilizing during processing.
• the liquid component can be supported in the voids around the filler by coating, the liquid component can be supported after laminating the barrier layer, adhesive layer, etc. onto the stretched sheet, making it easier to laminate the barrier layer or adhesive layer.
• impregnation refers to the penetration of the liquid component into the voids. Impregnation includes methods such as immersing the sheet in liquid or contacting the sheet with the mixed liquid in air by coating.
• the liquid component-containing sheet obtained in the manner described above contains a pyrethroid-based pesticide as the active ingredient, and becomes a sustained-release insect repellent sheet that releases this pesticide over time.
• Pests that are targeted by the sustained-release insect repellent sheet include, but are not limited to, flying pests such as mosquitoes, flies, horseflies, midges, moth flies, leaf beetles, stink bugs, leafhoppers, and crane flies, as well as crawling pests such as ants, pill bugs, woodlice, spiders, millipedes, centipedes, house centipedes, and caterpillars.
• flying pests such as mosquitoes, flies, horseflies, midges, moth flies, leaf beetles, stink bugs, leafhoppers, and crane flies
• crawling pests such as ants, pill bugs, woodlice, spiders, millipedes, centipedes, house centipedes, and caterpillars.
• sustained-release insect repellent sheets When sustained-release insect repellent sheets are soaked in liquid ingredients, they gradually become cloudy as the ingredients evaporate. Therefore, the degree of cloudiness can be used to gauge the extent of evaporation of the liquid ingredients. When used in insect repellent sheets, this serves as a so-called indicator display that shows the end of the effective period. This cloudiness gradually progresses once a certain amount of the liquid ingredients have evaporated, and once a certain point is reached, the cloudiness becomes smaller. Therefore, the color approaches the color indicating the end of the effective period sooner than when all the liquid ingredients have evaporated.
• the liquid ingredients contain surfactants and/or liquid paraffin that are difficult to volatilize, so they remain in the sheet even after the pyrethroid agent has finished evaporating. Therefore, the end of the effective period can be displayed at a time when the change in cloudiness is easily noticeable.
• Slow-release insect repellent sheets may be laminated with other layers, such as a barrier layer or adhesive layer, depending on the purpose. For example, by laminating a resin with gas barrier properties as a barrier layer, the amount of pyrethroid pesticide that volatilizes can be adjusted. Furthermore, by laminating an adhesive layer on top of the barrier layer, the sheet can be attached to various locations for use. As mentioned above, a liquid component can also be carried in the voids around the filler by application, so lamination can be done in a variety of ways without having to consider constraints such as the ability to stretch in the liquid component or the inhibition of adhesiveness by the liquid component.
• thermoplastic resin or liquid components various additives other than those mentioned above can be blended into the thermoplastic resin or liquid components as appropriate.
• additives such as ultraviolet absorbers, antioxidants, surfactants, colorants, pigments, dyes, natural essential oils, fragrances, lubricants, etc. may be blended to the extent that they do not interfere with the intended purpose.
• the sustained-release insect repellent sheet can be processed into the desired shape to suit the purpose. It can be enclosed in a molded frame and hung from a doorknob, or enclosed in a frame with hook-and-loop fasteners and attached to a screen door. It can also be enclosed in a perforated box and placed under a vending machine or in a rice bin. An adhesive layer can also be formed on the sheet and attached to a desired location such as a window sash or frame.
• a mixture 2 was prepared by mixing 70% by mass of polyethylene terephthalate (density 0.926 g/cm 3 , melting point 124°C, MFR 0.8 g/10 min (190°C, 2160 g load) and 30% by mass of low-density polyethylene (density 0.926 g/cm 3 , melting point 124°C, MFR 0.8 g/10 min (190°C, 2160 g load)).
• the mixtures were co-extruded using a T-die to form a laminate structure of layers of mixture 1 and mixture 2, and cooled with a chill roll to obtain unstretched film 1.
• the layer of mixture 1 was approximately 300 ⁇ m thick, and the layer of mixture 2 was approximately 150 ⁇ m thick.
• Figure 1 shows a schematic diagram of the cross section of unstretched film 1.
• Unstretched film 1 was passed through nip rolls, a first stretching roll, a constant-temperature liquid bath (liquid bath temperature: 60°C), and a second stretching roll in the listed order, and then passed through a third roll consisting of a group of heated rolls (temperature: 80°C) for heat-relaxing and taken up to obtain sheet body A1.
• the constant-temperature liquid bath contained empenthrin (vapor pressure (30°C) 1.4 x 10-4 Pa) as chemical A, and stretching was carried out while the film was exposed to chemical A.
• the speed ratio (stretching ratio) between the first roll and the second roll was 5x, and the final speed ratio between the second roll and the third roll was 0.9x, resulting in 10% relaxation.
• the resulting sheet body A1 was designated Comparative Example 1.
• FIG. 2 shows a schematic diagram of the cross section of the sheet body after stretching.
• Example 1 A sheet body A2 was obtained in the same manner as in Comparative Example 1, except that liquid paraffin was mixed with the chemical A stored in the constant-temperature liquid bath of Comparative Example 1 to form liquid component A.
• the obtained sheet body A2 was used as Example 1.
• Example 2 A sheet A3 was obtained in the same manner as in Example 1, except that n-hexane (vapor pressure (30°C) 1.6 x 10 4 Pa) was mixed with the liquid component A stored in the constant temperature liquid bath of Example 1 to form mixed liquid A.
• the obtained sheet A3 was designated as Example 2.
• a sheet body B1 was obtained in the same manner as in Comparative Example 1, except that transfluthrin (vapor pressure (30°C) 4 ⁇ 10 -4 Pa) was used as chemical B instead of chemical A stored in the constant temperature liquid bath in Comparative Example 1.
• the obtained sheet body B1 was designated as Comparative Example 2.
• Example 3 A sheet body B2 was obtained in the same manner as in Comparative Example 1, except that isohexyldecyl stearate (2-hexyldecyl stearate) was mixed with the drug B stored in the constant-temperature liquid bath of Comparative Example 2 to form liquid component B.
• the obtained sheet body B2 was designated Example 3.
• the amount of each drug component contained in each liquid component extracted by the washing process was quantified using a gas chromatograph, and the drug content was calculated as a percentage by dividing the amount of each component by the initial weight.

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• General Health & Medical Sciences (AREA)
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Citations (8)

• 2025
  • 2025-03-10 JP JP2026512876A patent/JPWO2025211110A1/ja active Pending
  • 2025-03-10 WO PCT/JP2025/008758 patent/WO2025211110A1/ja active Pending
  • 2025-03-10 CN CN202580006371.7A patent/CN122249111A/zh active Pending

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