JP2003079303A - Porous ceramic liquid sucking wick - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous ceramic liquid sucking wick suitably usable as, e.g. a liquid sucking wick of a sucking up type thermal vaporizer, capable of affording excellent vaporizing performances, preventing chemical fluid leakage due to a rise in internal pressure of a chemical fluid container or the chemical fluid leakage due to overturn of the chemical fluid container and having excellent mass productivity. SOLUTION: This porous ceramic liquid sucking wick is characterized by forming a porous resin film on the surface of a porous ceramic molded product composed mainly of a siliceous ceramic raw material powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous ceramic liquid-wicking core which is preferably used as a liquid-wicking core of a wicking type heating and vaporizing device, and in particular, can obtain excellent vaporizing performance. The present invention relates to a device capable of reliably preventing a chemical liquid leak due to an increase in the internal pressure of the chemical liquid container and a chemical liquid leak due to a fall of the chemical liquid container, and having excellent mass productivity.

[0002]

2. Description of the Related Art In recent years, as a widely used evaporation method for chemical liquids, a part of a porous liquid absorbent core is immersed in the chemical liquid,
While supplying the liquid medicine to the liquid absorbent core, heating the upper portion of the liquid absorbent core to heat and evaporate the liquid medicine absorbed.
A wicking type heating evaporation device is known.

As the above-mentioned porous liquid absorbent core, generally, a porous ceramic compact formed by sintering a siliceous ceramic raw material such as clay or mica at a high temperature, clay, talc, kaolin, pearlite, diatom. Soil, gypsum, bentonite, glass fiber, asbestos, silica,
Inorganic powders such as alumina, silica-alumina, zirconia, wood powder, activated carbon, cellulose, pulp, and linters, and organic powders fixed and molded with a sizing agent such as starch and carboxymethyl cellulose are used. Such a liquid absorbent core is microporous and has a relatively good liquid absorbing property. However, as a problem when using the absorbent core as described above, when the temperature or pressure changes,
There is a phenomenon in which the internal pressure in the chemical liquid container increases due to the expansion of the chemical liquid, and as a result, the chemical liquid is pushed up through the liquid absorbent core to cause chemical liquid leakage.

In order to improve such a problem, in Japanese Utility Model Publication No. 45-14913 and Japanese Utility Model Publication No. 3-50878, a notch or a vent is provided in an inner plug for holding a liquid absorbent core in a chemical liquid container. It is disclosed that the inside and outside of the liquid medicine container are communicated with each other. However, by overturning the chemical solution container during use or storage, a chemical solution leaks from a notch or a vent hole, which causes new problems such as contamination of the surroundings and early consumption of the chemical solution.

Further, Japanese Patent Laid-Open No. 10-245086 discloses a liquid absorbent core in which a vertical groove is formed on the side surface. However, in the case of a porous liquid absorbent core, there is a problem in physical properties. If care is not taken in handling during manufacture, the groove is likely to be damaged, and there is a problem that the groove is crushed when it is inserted into the inner plug.

[0006] Therefore, in recent years, as a solution to the above problems, Japanese Patent Laid-Open No. 2001-86919 has been proposed.
The invention disclosed in the publication is proposed. According to this gazette, the ventilation holes of fine unevenness which vertically communicate with at least a part of the outer peripheral surface of the porous liquid absorbent core are formed by a mold having a textured surface or a sandblasted surface, whereby a chemical solution container It is said that it is possible to prevent the leakage of the chemical liquid due to the rise of the internal pressure and the leakage of the chemical liquid due to the overturning of the chemical liquid container.

[0007]

However, the porous liquid absorbent core disclosed in the above publication has the following drawbacks. First of all, in the case of a porous ceramic liquid absorbent core, the state of the extremely thin skin layer existing on the surface is changed by making the surface uneven. As a result, since the pores on the surface of the porous liquid absorbent core are unevenly present, the evaporation amount varies, and the chemical liquid does not evaporate as a gas from the porous liquid absorbent core and overflows as a liquid. Will cause the deterioration of. Secondly, the mold used for molding is a mating mold, but when hard ceramic is molded, the mold wears severely, and convex streaks are formed on the surface of the liquid absorbent core at the part corresponding to the mating surface. Will be raised. The degree of protrusion depends on the degree of wear, and if the amount of wear increases, the size of the unevenness intended by the mold may be far exceeded. In this case, the amount of the evaporated chemical liquid is different from the designed amount, and in addition, when the chemical liquid container falls down, the chemical liquid may leak. In order to prevent this problem, it is uneconomical because the hard mold must be changed frequently. Thirdly, the normal rod-shaped molded body has improved productivity by performing extrusion molding even if it is porous, but in the case of mold molding, it is significantly inferior to extrusion molding in productivity, The manufacturing cost will increase significantly.

As described above, it is difficult for the porous liquid absorbent core disclosed in Japanese Patent Laid-Open No. 2001-86919 to obtain excellent evaporation performance, and there is a possibility that chemical liquid leakage may occur. It has the drawback of being inferior in productivity and increasing in manufacturing cost.

The present invention has been made on the basis of the above points, and an object of the present invention is to obtain an excellent transpiration performance, and to prevent leakage of a chemical liquid due to an increase in the internal pressure of the chemical liquid container or a fall of the chemical liquid container. Another object of the present invention is to provide a porous ceramic liquid absorbent core that can reliably prevent chemical leakage and is excellent in mass productivity at low cost.

[0010]

In order to achieve the above object, a porous ceramic liquid absorbent core according to claim 1 of the present invention is a porous ceramic molded article composed mainly of siliceous ceramic raw material powder. Is characterized in that a porous resin film is formed on the surface of. A porous ceramic liquid absorbent core according to a second aspect of the invention is characterized in that the constituent material of the porous resin film is a silicone resin.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The porous ceramic molded product used in the present invention is generally a ceramic molded product obtained by mixing a siliceous ceramic raw material such as clay or mica as a main component with various additives and firing it at a high temperature. Goods can be used. As an example, the applicant may apply for a patent application 2000-3.
The porous ceramic molded article proposed in No. 00001 is mentioned. Here, various additives, barium titanate, glaze, organic short fibers, talc, zirconia, wood powder, acrylic resin, polyolefin resin, activated carbon, carbon black, charcoal, graphite, coke, tar pitch, water glass,
Examples include carboxymethyl cellulose and the like.

In the present invention, the porous ceramic liquid absorbent core is formed by forming the porous resin film on the surface of the porous ceramic molded article having the above-mentioned constitution, and thereby excellent vaporization performance is obtained. In addition, the leakage of the chemical liquid due to the rise of the internal pressure of the chemical liquid container and the leakage of the chemical liquid due to the overturning of the chemical liquid container are prevented.

Here, the constituent material of the porous resin film is liquid at room temperature, and the heater temperature (about 14
Any resin may be used as long as it has a heat resistance higher than 0 ° C. and is not particularly limited. However, it is preferably quick-drying and fast-curing. Further, it is preferable that this resin can be diluted with a solvent and can be foamed by blending a foaming agent. Examples of suitably used materials include silicone resin, epoxy resin, and polyimide resin.
Of these, silicone resins are particularly preferable because they are low in cost and easy to handle.

As a method of forming the porous resin film, for example, the following method can be mentioned. First, the above resin material, for example, a silicone resin is applied to the surface of the skin layer of the porous ceramic molded product. At this time, the resin concentration is preferably about 2 to 4 times diluted with a solvent, assuming that the solid content of the silicone resin is about 50%. next,
The solvent in the resin is blown dry at room temperature. Furthermore, 150 ℃
The resin is cured by heating at ˜180 ° C. to form a porous resin film. At this time, a large amount of air contained in the porous ceramic molded product expands and blows out toward the surface, so that the resin film foams. In addition, some of the bubbles generated by foaming burst and become concave. This state will be described with reference to FIG. 1. A porous resin film 1b is formed on the surface of the porous ceramic molded product 1a. However, the porous resin film 1b contains a large amount of bubbles 1c inside, and thus the bubbles are not formed. A large number of recesses 1d, which are ruptured and become concave, are also generated.

The generation conditions of the bubbles 1c and the recesses 1d are as follows.
It depends mainly on the concentration of the resin solution. The lower the concentration of the resin solution is, the more the bubbles 1c and the recesses 1d are generated. Here, when it is desired to further generate a large amount of bubbles 1c and concave portions 1d, a commercially available foaming agent may be appropriately mixed. Further, when it is desired to increase only the concave portion 1d, it is effective to preliminarily absorb water and moisture in the porous ceramic molded product 1a.

Bubbles 1 in the porous resin film 1b as shown in FIG.
Since the contact point between c's has a narrow opening, gas such as air, gas, and water vapor can pass through it well, but liquid such as solution in which a drug is dissolved and liquid such as water pass through only a small amount. Further, since the contact points between the bubbles 1c decrease toward the surface of the porous resin film, the gas flow amount is more porous than in the direction from the porous ceramic molded product 1a to the surface of the porous resin film 1b. The direction along the surface of the ceramic molded product 1a is overwhelmingly large. The gas flowing through the film is exhausted into the atmosphere at this portion, that is, at the contact point between the bubble 1c and the recess 1d, because there are many recesses 1d on the way.

As described above, the porous resin film according to the present invention has a structure in which the gas flow passage, which is the contact point between the bubbles 1c, and the gas exhaust portion, which is the contact point between the bubbles 1c and the recess 1d, are connected. It is characterized by

When the porous ceramic liquid absorbent core having such a porous resin film is installed in the chemical liquid container, the pressure difference between the inside of the chemical liquid container and the atmosphere causes the recess 1d to pass through the bubbles 1c in the porous resin film. Since the liquid comes out and is made uniform, the phenomenon that the liquid leaks due to the increase in the internal pressure of the liquid container does not occur. At this time, the opening for the chemical solution at the connection point between the bubble 1c and the recess 1d and the connection point between the bubbles 1c is narrow, and does not induce a large amount of leak of the chemical solution. Therefore,
Even if the liquid medicine container is accidentally tumbled during use or storage, liquid chemical leakage does not occur. Further, since the bubbles 1c are not continuous pores, they are not absorbed up to the heated portion above the porous ceramic liquid absorption core and are not associated with evaporation.

The thus-obtained porous ceramic liquid absorbent core of the present invention is used for insecticidal, sterilizing, aroma and the like.
It can be suitably used as a liquid absorbent core of a wicking type heating evaporation device for heating and scattering chemicals such as various insecticides, bactericides, deodorants, and fragrances.

FIG. 2 shows an example of a wicking type heating evaporation device suitable for using the porous ceramic liquid absorbent core according to the present invention. In FIG. 2, reference numeral 3 is a drug solution container containing a drug solution 4, which is detachably housed and held in the instrument body 2. The chemical liquid container 3 has a porous ceramic liquid absorbent core 1 and an inner stopper 5
And the annular heating element 6 is disposed around the upper portion of the porous ceramic liquid absorption core 1. Reference numeral 7 is a power cord, and by energizing through the power cord 7, an annular heating element 6 is used to form the porous ceramic liquid absorption core 1
The upper part is heated so that the drug solution 4 sucked up by the capillary phenomenon is evaporated from the top opening 8 provided on the upper part of the instrument body 2.

The porous ceramic absorbent core according to the present invention is different from the conventional example (the absorbent core disclosed in Japanese Patent Laid-Open No. 2001-86919) in the following points. (1) Since the skin layer of the porous ceramic is not directly processed, the evaporation performance does not deteriorate. (2) The porous resin film closes the fine pores, which pass only water vapor or solvent vapor, among the pores on the surface of the skin layer of the porous ceramic, but does not close the relatively large pores through which the chemical solution passes. Absent. Therefore, although the amount of chemical evaporation is shifted in the downward direction, it works in a stable direction so that effective chemical evaporation occurs. (3) The porosity of the porous resin film, the size of the bubbles, and the recesses are
Since it can be arbitrarily changed depending on the concentration of the constituent material of the porous resin film, the present invention can flexibly cope with the leakage of the chemical liquid, rather than molding with a mold. (4) The coat of the porous resin film is usually formed by dipping or spraying, but the thickness can be made uniform. Thus, surface ridges, such as striated protrusions on the ceramic surface due to die wear, are essentially impossible. (5) A continuous extrusion method can be used for molding the porous ceramic molded product, which is economically advantageous.

[0022]

EXAMPLES Examples of the present invention will be described below. Details of the compounding materials used in this example are shown in Table 1.

First, the compounding materials shown in Table 2 were thoroughly mixed, water was added as a kneading liquid, and the mixture was kneaded by a kneader. Next, this kneaded product was extrusion-molded into a round bar shape by a vacuum extrusion molding machine having a nozzle having a diameter of 8.1 mmφ. The obtained round bar shaped product was cut into a length of 80 mm, naturally dried for 1 hour, and further dried for 15 minutes with an infrared lamp. Then, this rod-shaped molded product was placed horizontally in a firing furnace and fired. The firing was carried out by first degassing at 450 ° C. for 2 hours, holding at 900 ° C. for 2 hours, and further holding at 1200 ° C. for 2 hours to lower the temperature. The rate of temperature increase / decrease is 360 ° C. per hour, and the firing atmosphere is all in the air. The obtained porous ceramic molded product was dipped in a silicone solution, which is a constituent material of the porous resin film, and after natural drying, 1
It was baked by heating at 50 ° C. for 15 minutes. As the silicone solution, a commercially available product was used after being diluted 4-fold.

The thus-obtained porous ceramic liquid absorbent core according to this embodiment is attached to a liquid medicine container containing a commercially available liquid medicine to prepare a wicking type heating evaporation device as shown in FIG. A liquid leak test was performed by incorporating the device. Three types of liquid leakage tests were performed: an upright test and an inverted test assuming storage, and a transpiration test assuming use. The test results are shown in Table 3.

In the upright test, the wicking type heating and evaporation device was kept upright, kept at room temperature for 24 hours, and then kept at 40 ° C. for 2 hours for two times, and the weight of the leakage of chemical liquid was checked. It was measured. The inversion test is performed by holding the wicking heating evaporation device at 30 degrees and holding it in an atmosphere of 5 ° C for 2 hours at 40 ° C.
The weight of the leakage of the chemical liquid was measured by repeating 2 cycles of holding for 2 hours. In the transpiration test, 10 cycles of energization for 10 hours followed by 2 hours of non-energization were repeated 10 times to measure the weight of the chemical solution that overflowed as a liquid from the porous ceramic liquid absorption core and accumulated in the inner plug. The value converted per cycle was used as the evaluation value.

For comparison, a sample not coated with a porous resin film (hereinafter, comparative example) was also subjected to the same liquid leak test as in this example. From Table 3, it can be seen that the porous ceramic liquid absorbent core according to the present example has a weight of liquid leakage of 1/4 to 1/5 in the upright test and the inverted test, as compared with the comparative example. From this, it is obvious that the porous resin film acts to prevent the leakage of the chemical liquid due to the rise of the internal pressure of the chemical liquid container and the leakage of the chemical liquid due to the overturning of the chemical liquid container. Also, looking at the results of the transpiration test, the porous ceramic liquid absorbent core according to this example has a smaller amount of liquid leakage than the comparative example. From this, it is clear that excellent transpiration performance can be obtained by forming the porous resin film.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

As described in detail above, according to the present invention, excellent vaporization performance can be obtained by mixing bubbles and recesses in the porous resin film formed on the surface of the porous ceramic molded article. In addition, it is possible to reliably prevent the leakage of the chemical liquid due to the increase in the internal pressure of the chemical liquid container and the leakage of the chemical liquid due to the overturning of the chemical liquid container. Further, the porous ceramic molded product can be molded by an extrusion molding method excellent in mass productivity, and a mold as in the conventional example is not required, so that the manufacturing cost can be significantly reduced. Therefore, it becomes possible to provide the porous ceramic liquid absorbent core at a low cost.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention and is a schematic cross-sectional view showing the structure of a porous resin film formed on the surface of a porous ceramic molded product.

FIG. 2 is a view showing an embodiment of the present invention, and is a schematic cross-sectional view showing the structure of a wicking type heating evaporation device to which a porous ceramic liquid wick can be applied.

[Explanation of symbols]

1 Porous ceramic absorbent core 1a Porous ceramic molded product 1b Porous resin film 1c bubbles 1d recess 2 instrument body 3 drug solution container 4 chemicals 5 Inner stopper 6 heating element 7 power cord 8 Top opening

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C04B 41/84 C04B 41/84 AF term (reference) 2B121 CA04 CA15 CA46 CA54 CA60 FA15 4C080 AA03 AA04 BB02 BB03 BB05 BB07 CC01 HH02 JJ01 KK04 LL01 NN02 NN29 QQ14 4F100 AD00A AD03A AD09A AK01B AK52B DJ01A DJ01B GB90 JL00 JL02 JM02B

Claims (2)

[Claims] 1. A porous ceramic liquid absorbent core, comprising a porous resin film formed on the surface of a porous ceramic molded article composed mainly of siliceous ceramic raw material powder. 2. The porous ceramic liquid absorbent core according to claim 1, wherein the constituent material of the porous resin film is a silicone resin.