JPH072072B2 - Insecticide heating evaporator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention mainly relates to a heating evaporator for efficiently and rapidly evaporating an insecticide having a low vapor pressure at a high temperature.

[Conventional technology]

Conventionally, there are various kinds of electric mosquito traps as a device for impregnating a porous plate piece with an insecticide, placing it on a heating plate and heating and evaporating it, but most of these are around 165 ° C at the center of the lower surface of the heating plate. , A relatively small heating element is attached, and a temperature gradient is provided so that the temperature of the surface of the heating plate decreases from the center to the periphery by about 20 ° C, and an insecticide made of a paper plate with a thickness of about 3 mm. Using an impregnated mat, the evaporation rate of the insecticide is slowed by the heat insulation effect due to its thickness and the temperature gradient on the surface of the heating plate.For example, in the case of pinamine forte, it evaporates at a rate of about 3 mg per hour for 10 to 12 hours. I am trying to continue. Also, in the control of harmful insects such as cockroaches, house dust mites and bed bugs, the pyrethroid insecticide permethrin is used, but since the vapor pressure is remarkably low, fine particles of the drug are released into the air using high temperature and high heat fumes, A drug has been developed that diffuses an effective amount of the drug into the voids where the pests inhabit.

Examples of commercial products include smoke agents and known pest control smokers (see Japanese Patent Publication No. 59-28370). The former smoke agent is a mixture of a heat-resistant container with a large amount of heat and fumes and a pesticide, which is solidified and enclosed. The high temperature and a large amount of fumes emit the drug as smoke particles of 0.1 to 6μ. The latter is equipped with an electric heater in the upper cavity of a trumpet-shaped tubular body with a wide inner diameter at the bottom. An insecticide element containing a plurality of through holes containing an insecticide in the upper body opening is detachably mounted, and the insecticide element is heated by high-temperature heat generation of 150 to 450 ° C by an electric heater. , A device designed to evaporate the insecticide.

[Problems to be Solved by the Invention]

Like an electric mosquito catcher, a mat with a high porosity is impregnated with a pesticide with a relatively high vapor pressure around 2% of its volume,
When placed on a heating plate of relatively low temperature and evaporated at a minute rate of about 3 mg per hour, the chemicals volatilize slowly from the mat surface, but the vapor pressure is extremely low for exterminating cockroaches, house dust mites, bed bugs, etc. permethrin in the particulate, short there is a need to be dissipated at a rate of about spatial volume 1 m ³ per 50mg, in the 6-mat room
A release of about 1,200 mg is required. In order to rapidly evaporate the mat impregnated with this, the temperature of the upper layer of the mat must be heated so as to approach the temperature at which the drug permethrin causes an exothermic reaction. Even if heated near the temperature at which the exothermic reaction occurs, heat is dissipated by the heat insulating effect inside the mat and radiation from the surface and low temperature outside air, so the drug vaporization temperature of the upper layer of the mat decreases, so the vapor pressure of the drug is extremely low Become,
It could not be evaporated rapidly.

Also, in conventional mat-type electric mosquito catchers and evaporators that heat drug holding plates, the high-temperature convection generated by the heating element and the radiant heat radiated from the heating plates and mats are mostly radiated to the atmosphere. However, the object emits radiant heat in proportion to the fourth power of the absolute temperature, and its intensity is 100
If ℃ is 1, it will be about 4.8 at 280 ℃. Taking this as a concrete example, the radiant heat when the heating plate area is 30 cm ^{2 and the} emissivity is 0.8 is 3.6 W at 130 ° C, but 12.7 W at 280 ° C.
Therefore, the radiant heat rapidly increases as the temperature rises, and the radiant heat amount becomes larger than the evaporation heat amount of the drug. Therefore, the higher the temperature, the lower the thermal efficiency of the device.

In addition, when the evaporation mat is heated at a high temperature, the high-pressure steam generated in the voids in the lower layer of the mat is condensed inside the mat because the temperature of the upper layer is low, and impedes the permeation of the vapor. Although it is inevitable that it will flow laterally along the edge of the mat and it will volatilize from the periphery of the mat, the evaporation rate will be slow because the gap is narrow and the resistance is large.

Furthermore, since permethrin undergoes an exothermic reaction when it slightly exceeds 280 ° C and decomposes, the combustion agent is 270 to 350 in order to evaporate permethrin in the above-mentioned smoke agent or smoking device.
In a smoke device, it is heated at an exothermic temperature of 150 to 450 ° C, so when the drug mixed particles or the insecticide element reaches the exothermic reaction temperature of the drug or higher, a part of the drug is completely evaporated until the contained permethrin evaporates. May be thermally decomposed.

The present invention focuses on these problems, and provides a heating / evaporating device for rapidly and efficiently evaporating a drug from a mat holding a large amount of the drug, using radiant heat or high heat convection emitted from a heating object. This is the purpose.

[Means for Solving the Problems]

In order to achieve the above object, according to the present invention, a heating plate (a constant temperature heating element (2) with an electric resistance is attached to the lower portion inside an upper opening of a tubular container (1) having an air hole in the lower portion ( 3)
A cover lid (9) which is installed over a cylindrical wall with a space provided and an exhaust port (7) is provided in the center of the ceiling portion, the inner wall of which efficiently radiates heat from the heating plate (3). (3) A heating and evaporation device for insecticide, characterized in that it is curved inward toward the upper side so as to be reflected at (3), and is attached to the upper edge of the tubular body (1).

For the cover (9), it is necessary to use a material that has heat resistance and low emissivity at high temperature. For example, aluminum plate, iron plate, ceramic or plastic, aluminum, zinc-aluminum alloy, etc. The one coated is effective.

Further, when several needle bars (8) are horizontally attached to the cover lid (9) from the lower portion of the inner wall of the cover at an equal height position, and the covering lid (9) is capped on the tubular device body (1), When (8) is brought into pressure contact with the evaporation mat placed on the heating plate (3), the mat can be brought into close contact with the heating plate (3).

It is effective to use a barium titanate-based semiconductor heater as the constant temperature heating element (2) mounted on the lower part of the heating plate (3) so that the heater temperature can be kept constant even if the load changes.

(Operation) When the device configured as described above is operated, the surrounding area is heated by the heating element in the upper part of the cylinder, outside air flows in from the lower part of the cylinder and becomes heat convection in the upper part of the cylinder, and the peripheral edge of the heating plate. Rises above the gap between the cover and the cylinder wall, enters the cavity formed between the cover and the top surface of the heating plate, and further inside the cavity, the surface of the heating plate or the evaporation mat placed on the heating plate and the inner wall surface of the cover. It is heated by radiant heat due to radiation and reflection, and transfer heat from those surfaces, and wraps the chemical vapor that evaporates from the mat due to high temperature and high heat convection, and becomes hot air from the exhaust port of the cover lid ceiling. And diffuse into the air.

Furthermore, by lowering the emissivity from the inner and outer wall surfaces of the cover, the radiant heat from the outer surface of the cover to the atmosphere is reduced and the inside of the device is kept warm. Efficiently reflects radiant heat to the mat,
Increase the temperature of the matte surface.

Also, if a coating with a high emissivity is applied to the inner wall surface of the cover, the radiation heat inside the cavity becomes stronger and convection becomes more active, increasing the calorific value of the constant temperature heating element, but increasing the temperature inside the cavity The evaporation and diffusivity of is improved.

〔Example〕

 An embodiment of the device of the present invention will be described.

As shown in FIG. 1, a cover lid (9), which is made of heat-resistant plastic and has an inner and outer wall surface coated with aluminum, is attached to the opening of the upper part of the cavity of the cylindrical body (1) made of heat-resistant plastic. An iron plate is used as the material of the heating plate (3) that is installed over the opening position at the upper part of the tubular container body (1) and is separated from the inner wall.
The thickness is 1 mm, the diameter is 62 mm, the peripheral edge is bent upward by 1 mm, and the surface is coated to prevent charring, and a constant temperature heating element (2) using a barium titanate-based semiconductor heater is attached to the bottom of the coating, and a heating plate (3 ) Surface temperature is kept at 280 ℃, and the thickness of 1.5 mm, diameter 60 mm, density of 0.42 g / cm ³ cotton linter paper is used as the substrate (4), and 1,500 mg of the pyrethroid insecticide permethrin is retained. , An aluminum foil having a thickness of 7 μ is attached to the evaporation surface of the substrate (4), and evaporation holes (6) having a diameter of 0.3 mm penetrating the film are formed in a zigzag pattern at intervals of 1 mm in the evaporation mat (No. 1). (Fig. 4) on which the tubular container (1) is placed
When the lower edge of the cover (9) is loosely fitted to the upper edge of the cover, it is horizontally inserted from the lower part of the inner wall of the cover (9) at a uniform height to 1.5 m.
A stainless needle bar (8) of m diameter adheres to the surface of the evaporation mat, and the evaporation mat is pressed against the heating plate (3) by the weight of the covering lid (9). Next, when the heat generator (2) was operated by the time switch (10) mounted below the inside of the body (1), the evaporation of the drug was completed in 25 minutes. This device has an area ratio of the exhaust port of the cover to the heating plate of 1: 7.

Also, using the same device, form a film (5) on the surface of the evaporation mat at a ratio of 4 mg / cm ² of aluminum foil powder using glycol / maleic acid resin as an adhesive, and vaporize the same as above. Evaporating the perforated and non-perforated and non-perforated non-perforated ones respectively, 35 minutes for mats with vapor holes in the powder coating and 40 minutes for those without vapor holes in the coating.
It took 80 minutes for a mat with no lid and no holes.

This is because in a coating that adheres aluminum powder, the powder surface is not a smooth surface like an aluminum foil film, but has irregularities, and the emissivity is higher than that of the foil film due to the gaps between the powder and the physical properties of the adhesive surrounding the powder. It seems that the temperature rises and the surface temperature decreases.

Also, the reason that the evaporation rate of the non-harmless, non-coated and non-porous mat is remarkably slow is considered to be that the large amount of radiant heat or transfer heat is dissipated from the surface of the mat to lower the evaporation temperature of the drug on the surface layer of the mat.

〔The invention's effect〕

As described above, the present invention is configured to rapidly evaporate the insecticide by using high heat convection and radiant heat emitted from an object, and has the following effects.

In the invention according to claim 1, the thermal convection heated by the heating element in the upper part of the cylinder of the cylindrical container enters the cavity formed on the heating plate inside the cover, and further radiates and Since it is heated by transmission, the atmospheric temperature on the surface of the evaporation mat rises, and the mat surface is efficiently exposed to the radiation and reflected heat from the inner wall surface of the cover, which suppresses the dissipation of heat from the surface and reduces the surface temperature of the mat. Since the drug evaporation temperature is raised, the drug evaporates rapidly.

When a coating with a high emissivity is applied to the inner surface of the cover, the temperature inside the cavity is increased by radiant heat, and convection becomes active, which promotes evaporation and diffusion of the drug.

The chemical vapor is volatilized and mixed into the high-temperature convection inside the cavity, and becomes hot air from the exhaust port and is diffused to the outside atmosphere, so the vapor is less condensed and the diffusivity is improved, increasing the effective efficiency of the chemical. At the same time, the amount of chemicals used is small and it becomes economical.

According to the second aspect of the present invention, even if the evaporation mat is curved or has elasticity due to heat, the mat is forcibly pressed against the heating surface by the needle bar to uniformly heat the mat. Therefore, the heating efficiency does not decrease.

[Brief description of drawings]

The drawings relate to the present invention. FIG. 1 is a perspective view of a part of the apparatus in section, and FIG. 2 is a perspective view of a part of the evaporation mat in section. (1) ... Cylindrical body, (2) ... Heating element, (3) ... Heating plate (4) ... Substrate, (5) ... Coating, (6) ... Steam hole (7) ... Exhaust port, (8) … Needle bar, (9)… Cover lid (10)… Time switch

Claims (1)

[Claims] 1. A heating plate having a lower surface provided with a constant temperature heating element (2) by electric resistance, which is suspended from a cylindrical wall near an opening of an upper part of a cavity of a cylindrical body (1) having an air port at a lower portion. Several needle bars (8) are installed from the lower part of the inner wall to a cover lid (9) in which (3) is erected, the inner wall is curved inward upward, and the exhaust port (7) is provided on the ceiling. When the cover is mounted horizontally and the cover lid (9) is loosely fitted to the upper opening of the tubular body (1), the needle bar (8) is in close contact with the evaporation mat placed on the heating plate (3). Then, the gravity of the cover lid (9) is applied to the needle bar (8) to press the evaporation mat, and the heating and evaporation device for insecticide is characterized in that.