Slow-release insect repellent sheet

Abstract

A slow-release insect repellent sheet is provided, which allows for easy adjustment of the release period of pyrethroid insecticides. The slow-release insect repellent sheet is a sheet containing a liquid component, wherein a filler is dispersed in a thermoplastic resin and a liquid component is loaded in the voids formed around the filler, wherein the loaded liquid component contains a pyrethroid insecticide as the active ingredient and contains a surfactant and / or liquid paraffin.

Description

Technical Field

[0001] This invention relates to a slow-release insect-repellent sheet. Background Technology

[0002] In the past, to prevent small animals, insects, and other pests from entering buildings and their associated equipment, vending machines, grain bags, rice bins, and other containers, insecticides, pesticides, and repellents were commonly used. Pyrethroid insecticides are frequently used as such insecticides, applied by spraying them from sprayers. However, spraying insecticides can lead to their loss and make it difficult to maintain their effectiveness long-term. Furthermore, there are concerns about environmental pollution from spraying insecticides.

[0003] As another method, it is known to preload an insecticide or similar substance into a sheet and then slowly release the insecticide or similar substance from the sheet. This method maintains its effect for a longer period compared to spraying. For example, Patent Document 1 describes a slow-release sheet made by stretching a resin composition containing a filler material, creating voids around the filler material, and containing a functional liquid component such as an insecticide within these voids. This slow-release sheet can release the liquid component over a long period while maintaining a certain release level.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2019-130729 Summary of the Invention The technical problem that the invention aims to solve While slow-release sheets containing insect repellents can release liquid components over a long period, insect activity is seasonal, and continuous release during inactive periods is ineffective. A longer effective period is not necessarily better; sometimes shortening the effective period and reducing the amount of insect repellent used, thereby lowering manufacturing costs, is more beneficial. In other words, for insect-repellent sheets that incorporate insect repellents, it is essential to control the release period of the liquid component within an optimal timeframe.

[0005] In the slow-release sheet of Patent Document 1, in order to allow more liquid components to be contained in the voids formed around the filler material through stretching, the liquid components cannot be distributed throughout the sheet if the voids are not connected. However, to make the voids connected, a large amount of filler material must be added and the sheet must be stretched at a high stretch ratio. As a result, in addition to the limitations of the stretch ratio and the amount of filler material added, the thickness of the sheet is also inevitably limited, making it difficult to change the content of liquid components inside the sheet under these conditions. Therefore, this leads to problems such as unnecessarily long duration of effect and increased costs due to the large amount of insect repellent added.

[0006] The purpose of this invention is to make it easier to adjust the content of insect repellents when this slow-release sheet is applied to insect-repellent sheets, thereby making it easier to adjust the release period.

[0007] Solution to the above technical problems The aforementioned technical problem is solved by a slow-release insect repellent sheet, which is a sheet containing a liquid component formed by dispersing a filler in a thermoplastic resin and loading a liquid component in the voids formed around the filler. The voids are interconnected, and the loaded liquid component contains a pyrethroid agent as the active ingredient, and also contains a surfactant and / or liquid paraffin.

[0008] The preferred pyrethroid agent is tetrafluorobenzyl, and in this case, it is preferable to include a fatty acid ester as a surfactant.

[0009] The method for manufacturing a slow-release insect-repellent sheet that solves the above-mentioned technical problems is a method of stretching an unstretched sheet in which a filler is dispersed in a thermoplastic resin, so that a liquid component is loaded in the voids formed around the filler to manufacture a sheet containing a liquid component. The manufacturing process is as follows: the liquid component contains a pyrethroid agent as the active ingredient; during or after stretching the unstretched sheet, the sheet is impregnated with a mixture of the liquid component and a volatile component; after loading the mixture in the voids, a heat relaxation treatment is performed while the volatile component evaporates.

[0010] Invention Effects According to the present invention, when using pyrethroid agents as the active ingredient, it becomes easy to adjust their release period, and it is possible to provide slow-release insect repellent sheets that meet the intended use. Attached Figure Description

[0011] 【 Figure 1 [Comparative Example and Embodiment] Schematic diagram of the cross-section of the unstretched film.

[0012] 【 Figure 2 [Comparative Example and Embodiment] Schematic diagram of the cross-section of the stretched sheet. Detailed Implementation

[0013] The preferred embodiments for carrying out the present invention will be described below.

[0014] The slow-release insect repellent sheet of the present invention comprises a sheet containing a liquid component, which is formed by dispersing a filler in a thermoplastic resin and loading the liquid component into the voids formed around the filler. The sheet before containing the liquid component is preferably composed of a thermoplastic resin. The thermoplastic resin is not particularly limited, but is preferably a resin that is easily stretched; polyolefins, polyamides, polyesters, polyvinylidene fluoride, etc., can be selected. To include the liquid component in the sheet, a polyolefin with excellent chemical resistance and low reactivity with the liquid component is preferred. If the crystallinity is too high, the active ingredient in the liquid component cannot penetrate the interior of the thermoplastic resin, which may result in insufficient release. Therefore, in the polyolefin, low-crystallinity resins such as low-density polyethylene and low-isotactic polypropylene are preferred. When using low-density polyethylene, the lower the density, the lower the crystallinity tends to be; a density of 0.895–0.925 g / cm³ is preferred. 3 The resin falls within the specified range. From the viewpoint of sheet stretching, low-density polyethylene (LDPE) is preferably linear LPE. The melting point of LPE is preferably 80–135°C. The softening point of LPE is preferably 45–90°C. Among linear LPE and branched LPE, branched LPE tends to be less prone to crystallization. From the viewpoint of slow release of the liquid components contained within the sheet, it is also preferable to mix branched LPE within a range that does not impede stretchability in order to further reduce crystallinity. By including branched LPE in a portion, it is also easier to form voids with the filler, thereby facilitating the formation of interconnected pores.

[0015] The filler mainly refers to inorganic fillers such as calcium carbonate, talc, silica, mica, zinc oxide, barium sulfate, titanium dioxide, and aluminum. However, it can also be an organic material as long as it exhibits properties that are incompatible with the thermoplastic resin constituting the sheet material and is hard at room temperature. Numerous voids are formed around the filler, particularly through stretching, and liquid components are loaded within these voids. The filler is preferably a substance that is not easily corroded by the liquid components; inorganic fillers are relatively more stable. Regarding the shape of the filler, the closer it is to a spherical shape, the easier it is to disperse, and the more uniform the size of the voids. Therefore, calcium carbonate is preferred. There are no particular restrictions on the particle size of the filler used here; it is appropriately selected according to the thickness of the sheet or the formation state of the interconnected pores, but an average particle size of 0.1–10.0 μm, as determined by the air permeation method, is preferred. The average particle size can be calculated from the specific surface area obtained by the Blaine air permeation test. For fillers, dispersing more fillers with smaller average particle sizes allows the liquid component to be released for a longer period at a certain evaporation rate. However, if the average particle size is too small, the individual pores will also become smaller, making it difficult to load the liquid component due to factors such as surface tension. From the viewpoint of loading a liquid component containing pyrethroid agents and surfactants or liquid paraffin, the average particle size is more preferably in the range of 0.5 to 3 μm.

[0016] To obtain interconnected pores around the filler, it is preferable to uniformly disperse it at a relatively high blending amount. Preferably, the filler is added to a level where it accounts for 40% by mass or more of the sheet mass ratio before the liquid component is included. More preferably, it is in the range of 40% to 70% by mass. By adding the filler within this range, the multiple pores formed by stretching can be connected, allowing the liquid component to be contained within the sheet, thereby enabling the loading of a large amount of liquid component. If the filler is less than 40% by mass of the sheet mass, it becomes a state of sparsely forming pores, which may result in the liquid component being loaded only near the sheet surface. Furthermore, when the filler exceeds 70% by mass of the sheet mass, the mass of the thermoplastic resin will be less than 30% by mass, and therefore the sheet may become brittle and difficult to handle.

[0017] Thermoplastic resin and fillers, along with any other additives, are kneaded together in an extruder and formed into a sheet, thus becoming an unstretched sheet. The extruder can be any known equipment, and the unstretched sheet can be produced by either the tubular method or the T-die method. In this invention, to facilitate stretching, ensure smooth and sufficient loading of the liquid component into the voids within the sheet, and allow for sustained release of the active ingredient over a sufficiently long period, it is preferable to process the sheet containing the liquid component to a thickness of 50–1000 μm. When processing to this thickness, the T-die method, which facilitates the formation of thicker unstretched sheets, is preferred.

[0018] The voids around the filler can be created by stretching the unstretched sheet after it has been cooled and cured. This stretching can be a known method of stretching using a speed ratio between rollers. When an unstretched sheet containing filler dispersed in a thermoplastic resin is stretched, voids are formed around the filler. These voids are formed under vacuum. If stretching is performed while exposed to a liquid component, the liquid component can be drawn up, thus loading the liquid component around the filler. If stretching is performed in air, air will enter around the filler. The voids around the filler are very fine, and once air enters the voids, the liquid component becomes difficult to enter due to surface tension and other factors. By utilizing the force of the suction when the voids are formed, a large amount of liquid component can be loaded into the sheet. As long as the liquid component can be loaded into the fine voids around the filler, it is difficult for the liquid component to leak out of the sheet.

[0019] The force attracting the liquid component is generated by deforming the unstretched sheet. When it is desirable to increase the attractive force through stretching, it is preferable to increase the stretch ratio. The connection of voids is also generated by deforming the unstretched sheet; stretching at a relatively high stretch ratio enables these voids to connect. If the voids are not connected, the liquid component cannot penetrate the interior of the sheet. Therefore, it is preferable to stretch the unstretched sheet at a stretch ratio of 3 times or more. On the other hand, if the stretch ratio is too high, the sheet is prone to breakage during production, or the excessively large voids caused by stretching may impair the slow-release properties. From this perspective, it is preferable to set the stretch ratio to 10 times or less.

[0020] The liquid component contained in the sheet material uses pyrethroid insecticides as the active ingredient. Pyrethroid insecticides have shown efficacy in controlling pests, and examples include methoxyfenozide, tetrafluorobenzyl, propargite, dextromethorphan, deltamethrin, deltamethrin, fenpropathrin, cypermethrin, permethrin, tetrabromopropylate, cypermethrin, and etofenprox, etc. In this invention, these substances can be used alone or in combination.

[0021] By loading liquid components into tiny pores, excellent sustained-release effects can be achieved, preferably using a vapor pressure of 1×10⁻⁶ at 30°C. -4 ~1×10 -2 Pa is a volatile pyrethroid insecticide that is volatile at room temperature. Examples of such volatile pyrethroid insecticides include methoxyfenozide, tetrafluorobenzylfenozide, propofol, and dextromethorphan.

[0022] In addition to pyrethroid insecticides, the liquid component also contains surfactants and / or liquid paraffin. Surfactants and liquid paraffin act as diluents to thin the pyrethroid insecticides within the liquid component. By adjusting the pyrethroid content in the liquid component, the evaporation rate and effective period of the final insect-repellent sheet can be adjusted. Furthermore, surfactants and liquid paraffin do not increase the surface tension of the entire liquid component, facilitating its distribution throughout the fine pores formed in the sheet. Moreover, surfactants and liquid paraffin are preferably substances that are almost non-volatile at room temperature. If volatile substances are used and evaporate during impregnation, the dilution rate of the pyrethroid insecticide can easily change, leading to uneven content. If they are released along with the pyrethroid insecticide during use, it becomes difficult to control the evaporation rate, making it challenging to determine the shelf life.

[0023] When tetrafluorobenzyl is used as a pyrethroid insecticide, fatty acid esters are preferred as surfactants. Examples of fatty acid esters include: diisobutyl adipate, diethylhexyl succinate, cetyl 2-ethylhexanoate, tri(2-ethylhexanoate)glyceryl ester, hexyl decyl ethylhexanoate, triethylhexanoate, neopentyl glycol diethylhexanoate, trimethylolpropane triethylhexanoate, pentaerythritol tetraethylhexanoate, neopentyl glycol didecanoate, ethylhexyl isononanoate, isonononoate, isonononodecyl isononoate, isotridecyl isonononoate, hexyl laurate, isopropyl myristate, and octyl myristate. The product list includes tetrafluorobenzyl dodecyl ester, isocetyl myristate, isopropyl palmitate, ethylhexyl palmitate, octyl palmitate, ethyl stearate, octyl stearate, isocetyl stearate, ethyl isostearate, isopropyl isostearate, hexyl decyl isostearate, isostearate, glyceryl triisostearate, polyglyceryl triisostearate, trimethylolpropane triisostearate, pentaerythritol tetraisostearate, ethyl oleate, caprylic / capric triglyceride, and octyl dodecyl 12-stearoyl stearate. Tetrafluorobenzyl has a melting point of approximately 33°C and exists as a mixture of solid and liquid at room temperature. When stretched to obtain a sheet containing the liquid component while exposed to the liquid component, the stretching groove is heated, and tetrafluorobenzyl exists in a liquid state. However, after stretching to obtain a sheet containing the liquid component, tetrafluorobenzyl solidifies at room temperature. Once tetrafluorobenzyl solidifies, not only will the feel and hardness of the sheet containing the liquid component change within the room temperature range, but solidification can also block or deform the pores, thus easily altering its volatility. By properly mixing tetrafluorobenzyl with fatty acid esters, crystallization can be adjusted, allowing it to remain in a liquid state even under normal temperature operating conditions.

[0024] Since liquid paraffin typically contains olefinic hydrocarbons, when the thermoplastic resin constituting the sheet is a polyolefin, the liquid component containing liquid paraffin exhibits good affinity with the sheet, and the liquid component easily penetrates into the pores. Therefore, when the liquid component does not require special treatment as with tetrafluorobenzyl esters mentioned above, it is preferable to add liquid paraffin, and the surfactant and liquid paraffin can be mixed within a range that does not affect dispersion.

[0025] The mixing ratio (by mass) of pyrethroid insecticides with surfactants and / or liquid paraffin in the liquid formulation can be appropriately selected considering factors such as the target effective period. When a longer effective period is desired, it is preferable to increase the mixing ratio of pyrethroid insecticides. When mixing tetrafluorobenzyl with a surfactant to prevent tetrafluorobenzyl from solidifying, a mixing ratio of tetrafluorobenzyl:surfactant in the range of 1:0.1 to 10 by mass is preferred.

[0026] The content of the liquid component in the sheet can be appropriately selected, but it is preferably 10-60% by mass. Since the content of pyrethroid insecticides can be adjusted using surfactants or liquid paraffin, when reducing the pyrethroid insecticide content, it is not necessary to reduce the liquid component content itself; it is sufficient to maintain manufacturing conditions that easily ensure sheet porosity. Increasing the liquid component content will create a large number of large pores. Therefore, excessively increasing the liquid component content will not only impair the sheet strength but also make the pore shape unstable, making it difficult to ensure sustained release.

[0027] For liquid components, it is also possible to mix in more volatile components that are more volatile than the active pharmaceutical ingredient. The volatile components referred to here are liquids at room temperature, specifically those with a vapor pressure of 1×10⁻⁶ at 30°C. 2 This refers to easily volatile substances with a vapor pressure above Pa. However, if the volatility is too high, it is difficult to treat them as liquids; therefore, the preferred vapor pressure at 30°C is 1 × 10⁻⁶. 5 Pa or less. Specifically, examples include n-hexane, toluene, o-xylene, etc., and substances that are easily miscible with pyrethroid agents, surfactants, and liquid paraffins as liquid components and have low reactivity with these components are preferred, with n-hexane being more preferred.

[0028] If a mixture of liquid and volatile components is used, and the sheet is stretched in this mixture, both components will be loaded into the voids. After being loaded into the voids, the volatile component evaporates rapidly. However, as it evaporates within the voids, it creates a force that draws the liquid component into the voids to fill the space previously occupied by the volatile component. This force can be used to draw liquid components that have seeped to the sheet surface due to shrinkage back into the voids. For example, if the sheet is stretched in a liquid mixture and then immediately subjected to heat relaxation (annealing) while being heated, the liquid component will seep to the sheet surface. However, this seepage can be prevented by pre-mixing the volatile component. Heat relaxation also inhibits sheet shrinkage over time, thus preventing deformation and seepage of the liquid component even during the use of insect-proof sheets.

[0029] When the thermoplastic resin of the sheet is a polyolefin and hexane is used as a volatile component, hexane easily blends with the polyolefin and, to some extent, penetrates into the fine voids formed by stretching. If even a small amount of the mixture of liquid component and hexane enters the voids, the evaporation of hexane will generate a force that draws the liquid component into the voids. Therefore, even without stretching in the mixture of liquid component and volatile component, simply coating the sheet with the mixture of liquid component and hexane, which already has voids formed around the filler, allows the liquid component to be loaded into the voids formed around the filler. If a barrier layer or adhesive layer is to be laminated onto a sheet containing a liquid component, not only will the liquid component hinder interlayer adhesion, preventing sufficient bonding, but there is also a concern about the evaporation of the liquid component during processing. However, if the liquid component can be loaded into the voids around the filler through coating, the liquid component can be loaded after the barrier layer or adhesive layer is laminated onto the stretched sheet, making the lamination of the barrier layer or adhesive layer much easier. In this specification, impregnation refers to allowing the liquid component to penetrate into the voids. Impregnation includes methods of immersing the sheet in a liquid or methods of contacting the sheet with a mixture by coating it in the air.

[0030] There are no particular limitations on the mixing ratio (mass ratio) of the liquid component and the volatile component. Whether the sheet is stretched in the mixture or loaded by coating the mixture, the preferred mixing ratio (mass ratio) is liquid component:volatile component = 1:0.1 to 10. The volatile component is also prone to volatilization during impregnation, which can easily lead to uneven distribution of the liquid component. Furthermore, if the volatile component remains in the sheet, it can cause excess odor components. Therefore, it is preferable to minimize unnecessary mixing and allow it to volatilize during manufacturing, minimizing its residue in the sheet. From this perspective, the mixing ratio (mass ratio) is more preferably in the range of liquid component:volatile component = 1:0.1 to 1.

[0031] The liquid-containing sheet obtained as described above contains pyrethroid insecticides as active ingredients, thus becoming a slow-release insect repellent sheet that releases them slowly.

[0032] The pests targeted by slow-release insect repellent sheets include, but are not limited to, flying pests such as mosquitoes, flies, horseflies, midges, moth flies, leaf beetles, stink bugs, leafhoppers, and giant mosquitoes, as well as crawling pests such as ants, woodlice, sowbugs, spiders, millipedes, centipedes, house centipedes, and caterpillars.

[0033] Slow-release insect repellent sheets, initially containing a liquid component, gradually become cloudy as the liquid evaporates. Therefore, by observing the degree of cloudiness, the extent of evaporation can be estimated. Applying this to insect repellent sheets can replace traditional indicators showing the end of the effective period. The cloudiness gradually appears as the liquid component evaporates to a certain degree, and then decreases after a certain point. Therefore, the color indicating the end of the effective period is close to being visible before all the liquid component has evaporated. In this invention, because the liquid component contains non-volatile surfactants and / or liquid paraffin, these components remain in the sheet even after the pyrethroid insecticide has completely evaporated. Therefore, adjustments can be made to indicate the end of the effective period when the change in cloudiness is easily noticeable.

[0034] Slow-release insect repellent sheets can be laminated with other layers such as barrier layers or adhesive layers, depending on the purpose. For example, by laminating a gas-barrier resin as a barrier layer, the volatilization rate of pyrethroid insecticides can be controlled. Furthermore, by laminating an adhesive layer on top of the barrier layer, it can be applied to various locations. As mentioned above, since the liquid component can also be loaded into the voids around the filler through coating, there is no need to worry about limitations such as adhesion being hindered by the liquid component or whether stretching is possible within the liquid component, and lamination can be performed using various methods.

[0035] In slow-release insect-repellent sheets, various additives other than those mentioned above can be appropriately blended into the thermoplastic resin or liquid components. For example, ultraviolet absorbers, antioxidants, surfactants, colorants, pigments, dyes, natural essential oils, fragrances, lubricants, etc., can be blended to the extent that they do not hinder the intended purpose.

[0036] Slow-release insect-repellent sheets can be processed into desired shapes for various applications. They can be enclosed in molded frames and hung on door handles, etc., or enclosed in frames with hook and loop fasteners and attached to window screens. They can also be enclosed in perforated boxes and placed under vending machines, or placed in rice bins, etc. Furthermore, they can be formed into an adhesive layer and attached to desired locations such as window sashes or frames.

[0037] Example The present invention will be described in more detail below through embodiments, but the technical scope of the present invention is not limited to the following embodiments.

[0038] [Comparative Example 1] Prepare mixture 1 and mixture 2. Mixture 1 contains linear low-density polyethylene (density 0.932 g / cm³). 3Melting point 123℃, melt flow rate (MFR) 3.0 g / 10 min (190℃, 2160 g load) 16% by mass, low-density polyethylene (density 0.923 g / cm³). 3 Melting point 112℃, MFR 1.5g / 10min (190℃, 2160g load) 16% by mass, ultra-low density polyethylene (density 0.900g / cm³). 3 The mixture contains 8% by mass of high-density polyethylene (density 0.956 g / cm³), with a melting point of 115℃ and an MFR of 2.0 g / 10 min (190℃, 2160 g load) and 60% by mass of calcium carbonate (average particle size 1.2 μm as determined by air permeation). 3 Melting point 135℃, MFR 0.8g / 10min (190℃, 2160g load) 70% by mass, low-density polyethylene (density 0.926g / cm³). 3 The materials, with a melting point of 124℃ and an MFR of 0.8 g / 10 min (190℃, 2160 g load) of 30% by mass, were co-extruded using a T-die method to form a laminated structure of layers of mixture 1 and mixture 2, and cooled with cooling rollers to obtain an unstretched film 1. The layer of mixture 1 is approximately 300 μm thick, and the layer of mixture 2 is approximately 150 μm thick. Figure 1 The diagram shows a cross-sectional schematic of the unstretched film 1.

[0039] For the unstretched film 1, after passing through the pressing roller, it is sequentially passed through a first stretching roller, a constant-temperature liquid bath (liquid bath temperature: 60°C), and a second stretching roller in the following order, and then passed through a third roller consisting of multiple hot roller groups for thermal relaxation (temperature: 80°C) and wound to obtain a sheet-like body A1. At this time, the constant-temperature liquid bath contains dextrorotatory pyrethroid (vapor pressure (30°C) 1.4 × 10⁻⁶) as agent A. -4 The stretching was performed while exposed to agent A (Pa). The speed ratio (stretching ratio) of the first roll to the second roll was 5 times, and the final roll speed ratio of the second roll to the third roll was 0.9 times, resulting in a 10% relaxation. The obtained sheet-like body A1 was used as Comparative Example 1. Figure 2 The diagram shows a cross-sectional view of the stretched sheet.

[0040] [Example 1] Liquid paraffin was mixed with reagent A stored in the constant-temperature liquid bath of Comparative Example 1 and used as liquid component A. Otherwise, flakes A2 were obtained in the same manner as in Comparative Example 1. The obtained flakes A2 were used as Example 1. In addition, liquid component A was mixed with reagent A (d-acetylenol) at a ratio of 40% by mass and liquid paraffin at a ratio of 60% by mass (d-acetylenol: liquid paraffin = 1:1.5).

[0041] [Example 2] Hexane (vapor pressure (30°C) 1.6 × 10⁻⁶) was mixed into liquid component A stored in the constant-temperature liquid bath of Example 1. 4 Pa), which was used as mixture A, and flakes A3 were obtained in the same manner as in Example 1. The obtained flakes A3 were used as Example 2. In addition, mixture B was mixed with liquid component A (a mixture of dextromethorphan and liquid paraffin) at a ratio of 70% by mass of liquid component A and 30% by mass of n-hexane (liquid component A: n-hexane = 1:0.4).

[0042] [Comparative Example 2] Instead of reagent A stored in the constant temperature bath of Comparative Example 1, tetrafluorobenzyl (vapor pressure (30°C) 4 × 10⁻⁶) was used. -4 Pa) was used as drug B, and otherwise, sheet-like material B1 was obtained in the same manner as in Comparative Example 1. The obtained sheet-like material B1 was used as Comparative Example 2.

[0043] [Example 3] Isohexyl decyl stearate (2-hexyl decyl stearate) was mixed with reagent B stored in the constant temperature liquid bath of Comparative Example 2, and this was used as liquid component B. Otherwise, flakes B2 were obtained in the same manner as in Comparative Example 1. The obtained flakes B2 were used as Example 3. In addition, liquid component B was mixed at a ratio of 40% by mass of reagent B (tetrafluorobenzyl) and 60% by mass of isohexyl decyl stearate (tetrafluorobenzyl: isohexyl decyl stearate = 1:1.5).

[0044] [Example 4] Hexane (vapor pressure (30°C) 1.6 × 10⁻⁶) was mixed into liquid component B stored in the constant-temperature liquid bath of Example 3. 4 Pa), which was used as mixture B, was otherwise obtained in the same manner as in Example 3. The obtained sheet B3 was used as Example 4. In addition, mixture A was mixed with liquid component B (a mixture of tetrafluorobenzyl benzoate and isohexyl decyl stearate) at a ratio of 70% by mass of liquid component B and 30% by mass of n-hexane (liquid component A: n-hexane = 1:0.4).

[0045] [Example 5] The constant temperature liquid bath of Comparative Example 1 was replaced with a hot air oven, and stretching was performed without exposure to liquid. Otherwise, an unimpregnated sheet 1 was obtained in the same manner as in Comparative Example 1. Next, a mixture B (a mixture of tetrafluorobenzyl benzoate, isohexyl decyl stearate, and n-hexane) was applied to the unimpregnated sheet mixture 1 using a roller coater to obtain a sheet C. The obtained sheet C is used as Example 5.

[0046] The following evaluation tests were conducted on the sheet-like structures of Examples 1-5, Comparative Example 1, and Comparative Example 2. The results are recorded in Table 1. Furthermore, the thickness of Examples 1-5, Comparative Example 1, and Comparative Example 2 was approximately 230 μm.

[0047] [Evaluation Test 1: Appearance] The surface of the sheet-like body was visually observed and evaluated according to the following evaluation criteria.

[0048] Level 1 (0): There are no particular problems with the appearance.

[0049] Level 2 (△): Problems exist but can be improved.

[0050] Level 3 (×): There is a significant problem.

[0051] [Evaluation Experiment 2: Content Rate] For each sample obtained by cutting Examples 1-5 and Comparative Example 2 into 5cm square pieces, after measuring their initial weight, they were ultrasonically cleaned with toluene at 60°C for 20 minutes, and the weight after cleaning was measured. The difference between the initial weight and the weight after cleaning was calculated as the content of the liquid component, and the percentage obtained by dividing the content by the initial weight was used as the liquid component content rate.

[0052] Next, the liquid components extracted through the washing process are quantified using a gas chromatograph. The percentage obtained by dividing the amount of each component by its initial weight is then used to determine the drug content.

[0053] Table 1

[0054] In Examples 1, 3, and Comparative Example 1, liquid seepage was observed on the surface of the sheet material. However, the seepage was improved by stretching the sheet material again in air. Comparative Example 2, like Example 1, also showed liquid seepage. Examples 2, 4, and 5 did not show any particular seepage, and the sheet material had a good appearance. In Comparative Example 2, crystalline substances ranging from transparent to white adhered to the surface of the sheet material, and the shape of the sheet material was unstable, rendering it unusable.

[0055] In Examples 1-5, the relationship between the liquid component content and the drug content is roughly based on the mixing ratio of each liquid component.

Claims

1. A slow-release insect-repellent sheet, comprising a sheet containing a liquid component, wherein a filler is dispersed in a thermoplastic resin, and a liquid component is loaded in the voids formed around the filler, wherein... The gaps are interconnected. The liquid component contained in the container includes pyrethroid insecticides as active ingredients and contains surfactants and / or liquid paraffin.

2. The slow-release insect-repellent sheet according to claim 1, wherein, The pyrethroid insecticide is tetrafluorobenzyl.

3. The slow-release insect-repellent sheet according to claim 2, wherein, It contains fatty acid esters as surfactants.

4. A method for manufacturing a slow-release insect-repellent sheet, comprising stretching an unstretched sheet containing a filler dispersed in a thermoplastic resin, thereby loading a liquid component into the voids formed around the filler to manufacture a sheet containing the liquid component, wherein... The liquid component contains pyrethroid insecticides as the active ingredient. During or after stretching the unstretched sheet, a mixture of liquid components containing volatile ingredients is impregnated and loaded into the voids. While the volatile ingredients are evaporating, a thermal relaxation treatment is performed.

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