JP5407501B2 - Manufacturing method of gas adsorption filter - Google Patents

Description

  The present invention relates to a gas adsorption filter such as a deodorizing filter or a chemical filter that adsorbs gas components in the air, a manufacturing method thereof, and a gas adsorption device equipped with the gas adsorption filter.

  Conventionally, various shapes of gas adsorption filters using an adsorbent have been reported in order to remove gas components in the air. Among them, a granular adsorbent molded or fixed can be manufactured at a relatively low cost, and is widely used as a gas adsorption filter typified by a deodorizing filter or a chemical filter. In recent years, gas adsorption filters with higher performance and longer life have been demanded. For example, a mixture of adsorbent particles and thermoplastic resin binder particles is heated, and adsorbent particles are bonded to each other by molten thermoplastic resin binder particles. A method has been proposed in which a base material is not required by making the adsorbent self-supporting, such as a method, and a high performance and long life are achieved by improving the filling amount of the adsorbent.

  In the filter manufacturing method in which adsorbent particles and binder particles are mixed and heat-molded, how to uniformly mix the adsorbent particles and binder particles is an important condition for moldability. This is because if the mixing property is poor, not only the filter strength is insufficient but also the powder falls off, causing a decrease in adsorption performance. In order to make the adsorbent self-supporting, it is required that almost all the adsorbent particles are in partial contact with the binder particles and the adsorbent particles are held together via the binder particles. However, since adsorbent particles and binder particles usually have poor adhesion in a dry state and differ in material, particle size, and density, they are uniform with adsorbent particles, especially when the binder particles are about 100 mesh or less. The binder particles having a high density are separated to the lower side. However, if the binder particles are made too fine with respect to the size of the adsorbent particles because the adhesion between the adsorbent particles and the binder particles is too much, the binder particles cover the entire surface of the adsorbent particles, and the resin is heated during heating. Since it becomes a film and closes the pores of the adsorbent particles, the adsorption performance of the filter is drastically lowered. As described above, since the adsorbent particles and the binder particles are different in size and density, it is difficult to uniformly mix them by simply mixing two kinds of particles, and at the same time, suppression of the filter removal performance is required. Therefore, various ideas have been made for the mixing method (see, for example, Patent Documents 1, 2, and 3).

  That is, the air filter described in Patent Document 1 is a mixture in which heated adsorbent particles are once mixed with a granular thermoplastic resin binder while stirring with a stirrer, and the obtained aggregate particles are heat-molded again. By not applying pressure, gaps are provided between the aggregates to reduce pressure loss.

  Further, the filter molded article described in Patent Document 2 is formed by filling a mold with a mixture of adsorbent particles and a binder made of thermoplastic resin particles, pressing and heating, bonding the mixture, and molding the surface. However, it is not completely covered with the binder, and a decrease in the bonding force due to the adhesive agent or the like is suppressed.

  In addition, the deodorizing filter described in Patent Document 3 is formed by compressing and molding a mixture containing powdered activated carbon, titanium oxide, an organic binder, an inorganic binder, and water, and then drying with a dryer. The coating of the activated carbon surface with the organic binder is suppressed by making the proportion of the inorganic binder larger than the proportion of the organic binder.

Japanese Patent No. 3612329 JP 2001-149730 A Japanese Patent No. 3234165

  In Patent Document 1, the surface of the adsorbent particles is obtained by mixing the adsorbent particles in a state where the adsorbent particles are preheated to a temperature at which the thermoplastic resin binder is softened and exhibits adhesiveness in order to improve the uniformity of the materials to be mixed. The binder particles easily adhere to each other and can be mixed uniformly. However, since it is necessary to preheat the adsorbent particles, it takes extra time to mold the filter and there is a problem of poor productivity. .

  Further, in Patent Document 2, no special contrivance is made in particular during mixing, and in order to perform uniform mixing simply by stirring the adsorbent particles and the thermoplastic resin particle binder with a mixer, Since selection of a material, a particle diameter, and a density is required and conditions are also limited, there is a problem that the manufacturing method is not versatile.

  In Patent Document 3, a considerable amount of water is added for two main reasons of uniform mixing and suppression of powder material scattering, and after molding, a considerable drying time is required to obtain a filter. In short, there was a problem of poor productivity.

  In the present invention, a gas adsorption filter, a manufacturing method thereof, and a gas adsorption device that solve such a conventional problem, have high productivity, and can be widely applied to materials having various materials, particle sizes, and densities are provided. It is intended to provide.

In order to achieve the above object, a method for producing a gas adsorption filter according to the present invention is a method for producing a gas adsorption filter in which adsorbent particles having gas adsorbing pores and thermoplastic resin particles are mixed and thermoformed. In addition, when mixing the adsorbent particles and the thermoplastic resin particles, an aqueous solution of a surface inactive substance having a surface tension of at least 80 mN / m is added, and the surface tension of the aqueous solution is increased. Suppresses moisture infiltration into the pores of the adsorbent particles, moistens the surface of the adsorbent particles even with a small amount of water, and improves the mixing with the thermoplastic resin particles. As a result, the productivity of the filter can be increased. Moreover, since the adsorbent particle surface is in a wet state and uniform mixing properties can be obtained regardless of the material quality, particle size and density, a highly versatile gas adsorption filter manufacturing method is provided. Can do.

  According to the present invention, the wettability of the surface of the adsorbent particles with a small amount of moisture improves the mixing with the thermoplastic resin particles, so the heating loss due to moisture evaporation during thermoforming is greatly reduced. It is possible to provide a method for manufacturing a gas removal filter with high productivity. Moreover, a high performance gas adsorption filter and gas adsorption apparatus can be provided by the manufacturing method.

Schematic diagram of gas adsorption filter of Embodiment 1 and schematic diagram of an enlarged portion of the filter Schematic diagram of the mixed state of particles when an alkali metal salt aqueous solution is mixed Schematic diagram of particle mixing state when water is mixed Schematic of needle mold with needle-like projections Schematic of the gas adsorption apparatus of Embodiment 2 Graph showing the viscosity torque of crushed coal against the amount of water added Graph of TG and DTA curves of crushed coal with added water

The invention according to claim 1 of the present invention is a method for producing a gas adsorption filter in which adsorbent particles having gas adsorbing pores and thermoplastic resin particles are mixed and thermoformed. When mixing the resin particles, an aqueous solution of an interface inactive substance having a surface tension of at least 80 mN / m is added.

  When a plurality of types of particles having different materials, particle sizes, and densities are mixed in a dry state, they often cannot be mixed well and often separated. At this time, the surface of the particles is moistened by adding a little water, and the particles are entangled with each other through the water and can be mixed uniformly. However, when the particles are adsorbent particles having a high surface area typified by activated carbon, the adsorbent particles have innumerable pores inside, and if water is included, water is easily contained in the pores. Absorbs water. This is more conspicuous as the surface area is higher. Depending on the activated carbon, 20 to 30% of water per unit weight is absorbed into the pores. For this reason, when uniformly mixing with the thermoplastic resin particles, it is necessary to mix a large amount of water together in order to make the surface of the adsorbent particles wet. It takes extra time and energy to evaporate. Therefore, in the present invention, by adding an aqueous solution of a surface-inert substance, the surface tension of the aqueous solution is increased to suppress the infiltration of moisture into the pores of the adsorbent particles, so that the adsorbent particles can be formed even with a small amount of water. The surface can be preferentially wetted, and the heat molding time can be shortened.

  The surface-inactive substance is a substance that produces an action opposite to that of a surfactant with respect to water, and has a property that the surface tension increases because the solute is biased toward the inside of the solution rather than the interface in the aqueous solution. Most inorganic salts, strong acids, and strong alkalis are known as surface-inert substances, and any substance that has the property of improving surface tension may be used in the present invention. In view of handling properties, it is preferable to use an inorganic salt. Examples of the adsorbent particles include granular activated carbon, granulated activated carbon, zeolite, silica, sepiolite, etc., and any particles can be used as long as adhesion with the thermoplastic resin particles can be secured. It can be selected according to the nature of the gas component to be used, and one kind or two or more kinds of adsorbent particles may be combined. In addition, examples of thermoplastic resin particles include polyethylene, polystyrene, polypropylene, polyvinyl acetate, polyamide, polyethylene terephthalate, polyamideimide, and the like, depending on conditions such as the particle diameter of the adsorbent particles and the heating temperature during thermoforming. Select the best one.

In particular, it is possible to significantly suppress the infiltration into the pores of the adsorbent particles by at least 80 mN / m surface tension of aqueous solutions, also to preferentially wet the surfaces of the adsorbent particles with a small amount of water This has the effect of shortening the heat molding time.

Further, in the present invention it surfaces inerts alkali metal salts der, water solubility of the alkali metal salt is characterized in that at least 30 wt%. Examples of the alkali metal include lithium, sodium, potassium, rubidium, cesium, and frangium, but lithium, sodium, and potassium salts are preferable in consideration of solubility in water, availability, and price. These alkali metal salts include various salts such as chloride salts, hydroxide salts, carbonates, hydrogen carbonates, sulfates, citrates, and tartrates. Since these alkali metal salts act as a surface-inert substance in an aqueous solution and improve the surface tension of the aqueous solution, the aqueous solution suppresses the infiltration of the adsorbent particles into the pores, and the adsorbent particles even with a small amount of water. The surface of the substrate can be preferentially wetted, and the heat molding time can be shortened.

In particular , in the present invention, the solubility of the alkali metal salt in water is at least 30 wt %, that is, the aqueous solution suppresses infiltration of the adsorbent particles into the pores by using an alkali metal salt having a solubility in water of 30 wt% or more. However, the surface of the adsorbent particles can be preferentially wetted even with a small amount of water, and the heat molding time can be shortened.

  In the present invention, the alkali metal salt is potassium carbonate. Potassium carbonate is more preferable as a surface-active agent because it is 112 g / 100 mL at a temperature of 20 ° C. in water and higher than other alkali metal salts, and is inexpensive and highly safe. The surface tension of the aqueous solution is also high, and the surface tension of 50 wt% potassium carbonate aqueous solution is 100 mN / m or more, which is higher than other alkali metal salts, and greatly infiltrates the pores of the adsorbent particles. Can be suppressed. In addition, potassium carbonate is a substance that is widely used as an additive, and has an effect of improving removal performance against acid gas.

  In the present invention, the mixing weight ratio of the thermoplastic resin particles to the weight of the adsorbent particles is 5 wt% to 30 wt%. By mixing adsorbent particles and thermoplastic resin particles and thermoforming them, it is possible for thermoplastic resin particles to bond adsorbent particles together to form a filter, but when the mixing weight ratio is 5 wt% or less Adhesive strength is weak and it is difficult to form a filter. When the mixing weight ratio is 30% or more, the strength is high, but the resin component increases so much that the surface of the adsorbent is covered, and the gas removal performance. Will fall. By setting the weight mixing ratio of the thermoplastic resin particles to the adsorbent particles in the range of 5% to 30%, a gas adsorption filter having high mechanical strength can be formed, and high gas removal performance can be provided. It has the action.

  In the present invention, the adsorbent particles are granular activated carbon. Granular activated carbon is cheaper than other adsorbent particles, and because activated carbon has pores of various sizes, it is suitable for adsorption removal of a wide range of gas components and has various odors. It is most suitable for deodorizing living spaces such as mixed homes. In addition, by attaching an impregnation agent to granular activated carbon, it is possible to cope with gas components that are difficult to adsorb with ordinary activated carbon, and it is possible to produce an excellent gas adsorption filter. .

  In the present invention, the melting temperature of the thermoplastic resin particles is 80 ° C to 140 ° C. There is a possibility that the adhering agent adhering to the adsorbent particles such as activated carbon is denatured and decomposed by heat and the performance is deteriorated. By using thermoplastic resin particles having a melting temperature in the range of 80 ° C. to 140 ° C., the gas adsorption filter can be molded without deteriorating the performance of the adhering agent.

  Further, the gas adsorption filter of the present invention is characterized in that a vent hole is provided by piercing a metal mold having a plurality of needle-like protrusions into the gas adsorption filter prepared by the above manufacturing method. A gas adsorption filter with a small can be manufactured.

  In addition, several methods can be considered as means for providing the vent hole. For example, a method in which a mold having a large number of needle-like protrusions is filled with a mixture of adsorbent particles and thermoplastic resin particles, and the mold is removed after heat molding. However, in this method, it is difficult to uniformly fill the adsorbent particles into the needle-like protrusions that are infinitely densely arranged, and it is not preferable in view of production efficiency.

  Further, a method of punching a heat-formed filter is conceivable. In this method, for example, a punching metal is continuously punched from the end of a filter using a machine having a plurality of punches. Not only will the particles break and cause powder to fall off, but the punched pieces will be lost, and the material cannot be used efficiently. In addition, the thickness of the filter to be processed is greatly limited, and it is difficult to process a thick filter.

  Therefore, in the present invention, as a means for providing a vent hole, a method is used in which a mold having a plurality of pointed needle-like protrusions is used, and this is pierced into a filter to provide a vent hole. In this way, since one vent hole is formed for one needle-like projection, the vent hole corresponding to the arrangement can be easily formed by arbitrarily arranging the needle-like projection.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

(Embodiment 1)
FIG. 1 shows a schematic diagram of a gas adsorption filter according to the present invention and a schematic diagram showing a mixed state of filter materials. As shown in FIG. 1, a gas adsorption filter 1 is composed of adsorbent particles 2 having gas adsorbing pores, thermoplastic resin particles 3 and an aqueous solution 4 of an alkali metal salt, and a plurality of circular shapes formed by heat molding. The vent holes 5 are provided so as to be regularly arranged.

  Examples of the adsorbent particles 2 include granular activated carbon such as crushed charcoal and granulated charcoal, granulated zeolite, silica, and the like, and has strength and can secure adhesion to a thermoplastic resin. However, granular activated carbon is cheaper than other adsorbent particles, and since activated carbon has pores of various sizes, it is suitable for adsorption removal of a wide range of gas components, It is most suitable for deodorizing living spaces such as homes where various odors are mixed. In addition, by attaching an impregnation agent to granular activated carbon, it is possible to cope with gas components that are difficult to adsorb with ordinary activated carbon, and it is possible to produce an excellent gas adsorption filter. . The type of adsorbent particles can be selected according to the nature of the gas to be deodorized, and one type or two or more types of adsorbent particles may be combined. Further, the particle diameter of the adsorbent particles 2 is preferably in the range of 8 mesh to 150 mesh, more preferably in the range of 30 mesh to 100 mesh. The adsorbent particles can be controlled to have various particle sizes depending on the material and the production method. For example, activated carbon is a fine powder having a particle size of about several tens of μm, crushed coal or granulated coal having a particle size of about several mm. and so on. When molding these, it is common to mix them with a binder component once in a powder form and form it into a slurry and then carry it on a substrate or the like. However, many binder components are required for molding. As a result, because the adsorbent is buried by the binder, the gas contact inside the pores of the adsorbent is hindered, and the performance may be greatly reduced. If the amount is reduced, the adhesive strength is weak and fine powder may fall off.

  On the other hand, when the particle diameter is as large as several millimeters, a large gap is formed in a portion where the adsorbents overlap with each other, so that the amount of filling decreases and the performance deteriorates. Therefore, by using adsorbent particles having a particle diameter in the above-mentioned range as the adsorbent, it is possible to prevent the burying of the adsorbent by the binder component and to increase the filling amount, thereby producing a high-performance gas removal filter. .

  The thermoplastic resin particles 3 are preferably resin particles called hot melt, and examples of the material thereof include polyethylene, polystyrene, polypropylene, polyvinyl acetate, polyamide, polyethylene terephthalate, and polyamideimide. Moreover, as a particle diameter of the thermoplastic resin particle 3, it is preferable that the particle diameter ratio of the thermoplastic resin particle with respect to the particle diameter of adsorbent particle is the range of 0.1-1. It becomes possible to control the thickness and area of the bonded portion by the particle diameter of the thermoplastic resin particles. However, if the particle size of the thermoplastic resin is too small relative to the particle size of the adsorbent particles that are to be adhered, most of the surface of the adsorbent particles is covered with the molten thermoplastic resin, and the gas is removed. Performance will be degraded. Therefore, by setting the particle size ratio of the thermoplastic resin to the particle size of the adsorbent particles in the range of 0.1 to 1.0, the gas adsorption filter 1 with high gas removal performance is formed while maintaining sufficient adhesive strength. It has the effect that it is possible.

  The mixing weight ratio of the thermoplastic resin particles 3 to the adsorbent particles 2 is preferably 5% to 30%, more preferably 10% to 20%. If the mixing weight ratio is 5% or less, the adhesive strength is weak and it is difficult to form a filter, and if the mixing weight ratio is 30% or more, the strength is high, but the resin component becomes too large and the surface of the adsorbent becomes large. The part is covered and the adsorption performance is lowered. By setting the weight mixing ratio of the thermoplastic resin particles to the adsorbent particles within the above range, a filter having high strength can be molded, and high adsorption performance can be obtained.

  Moreover, it is preferable that the melting temperature of a thermoplastic resin particle is 80 to 140 degreeC. There is a possibility that the adhering agent adhering to the adsorbent particles such as activated carbon is denatured and decomposed by heat and the performance is deteriorated. By using thermoplastic resin particles having a melting temperature in the range of 80 ° C. to 140 ° C., the gas adsorption filter can be molded without deteriorating the performance of the adhering agent.

  FIG. 2 schematically shows a mixed state of particles when adsorbent particles, thermoplastic resin particles, and an aqueous solution of an alkali metal salt are mixed. FIG. 3 schematically shows the mixed state of the particles when water is mixed instead of the aqueous solution of the alkali metal salt. As shown in FIG. 2, the mixture of the alkali metal salt aqueous solution 4 has a high surface tension, so that it is difficult for water to infiltrate into the pores 6 of the adsorbent particles 2. Moisture is present to form a film. For this reason, it is possible to make the surface of the adsorbent particles 2 wet with a small amount of water, and the mixing property with the thermoplastic resin particles 3 is improved. On the other hand, as shown in FIG. 3, the mixture of water 7 is absorbed into the pores 6 of the adsorbent particles 2, so that the pores are in water to make the surface of the adsorbent particles 2 wet. 7 need to be filled and a lot of moisture must be mixed. The surface tension of the aqueous solution is preferably 80 mN / m or more, more preferably 100 mN / m or more. The surface tension of water is about 73 mN / m at room temperature, and when the alkali metal salt is dissolved in water, the surface tension rises because the force that ions try to exist in the water works. In particular, high-concentration aqueous solutions in which the solubility of alkali metal salts is just before the surface have a considerably high surface tension. By increasing the above value, water infiltration into the pores of the adsorbent particles can be greatly suppressed. Has the effect of being able to

  As the alkali metal salt, any substance that can increase the surface tension may be used. In particular, potassium carbonate and sodium hydroxide are preferable as substances having a large effect of increasing the surface tension. More preferred. The concentration of the aqueous solution is preferably 30 wt% or more, more preferably 45 wt% or more. Moreover, the addition amount of aqueous solution is 2 wt%-20 wt% with respect to the weight of adsorbent particle, More preferably, it is 2 wt%-5 wt%. By carrying out like this, potassium carbonate aqueous solution shows high surface tension of 80 mN / m or more, and the infiltration of the water | moisture content inside the pore of adsorbent particle | grains is suppressed. As a result, the surface of the adsorbent particles can be moistened even with a small amount of water, and the mixing time with the thermoplastic resin particles can be improved, so that the heating time at the time of thermoforming can be greatly shortened. It has the effect that the property can be enhanced.

  FIG. 4 shows a schematic diagram of a wire mold having needle-like protrusions. As shown in FIG. 4, the needle mold 8 has a shape in which a needle-like protrusion 10 is fixed to a plate-like base portion 9 as a base, and a vent hole can be easily provided by piercing this into a gas adsorption filter. Can do. By arbitrarily changing the diameter and pitch of the needle-like protrusions 10, the air holes 5 corresponding to the mold can be provided. The diameter of the needle-like protrusion 10 may be changed according to the pressure loss that is the specification of the deodorizing filter or the wind speed distribution when installed in the housing, but the diameter R is preferably in the range of 0.5 mm to 5 mm. More preferably, it is in the range of 1 mm to 2 mm. A plurality of types of needle-like protrusions 10 may be used in combination. Further, the pitch of the needle-like protrusions 10 may be changed in accordance with the pressure loss that becomes the specification of the filter or the wind speed distribution when installed in the housing, but the pitch P is in the range of 1.2R to 2.5R. It is preferable that the range is 1.5R to 2R. At this time, it is preferable to arrange six holes around the vent hole 5 at intervals of 60 degrees, and this is the closest packing arrangement close to a honeycomb structure in which regular hexagons are arranged. With this arrangement, since the pitch between the adjacent vent holes 5 is constant, there is an effect that it is possible to provide a gas adsorption filter that can achieve both strength and adsorption performance with low pressure loss.

  4 may be preliminarily heated at a temperature equal to or higher than the melting temperature of the thermoplastic resin so as to pierce the wire mold and heat mold the material by the heat of the wire mold, and at the same time provide a vent hole, By doing so, it is possible to produce a molded filter provided with a vent hole in a single step, and the productivity can be greatly improved.

(Embodiment 2)
A schematic diagram of a gas adsorption apparatus according to the present invention is shown in FIG. The same configurations and operations as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 5, the gas adsorption device 11 is formed by thermoforming a mixture of adsorbent particles 2, thermoplastic resin particles 3 and an aqueous solution 4 of an alkali metal salt, and regularly arranging a plurality of circular vent holes 5. The gas adsorbing filter 1 and the air blowing means 12 provided in the housing 13 are provided inside the housing 13 having the suction port and the air blowing port. The filter 1 adsorbs and removes and discharges clean air from the outlet. As a result, it is possible to provide a high-performance gas adsorbing device that has air permeability and low pressure loss but has high one-pass adsorption performance.

(Example)
Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 and Comparative Example 1
The amount of water required until the surface of the adsorbent particles became wet was confirmed.

  20 g of crushed charcoal having a particle size in the range of 30 to 60 mesh was placed in a container, and water was added stepwise to sufficiently stir. Viscous torque acting on the rotor of this crushed charcoal was measured with a digital viscometer (manufactured by Toki Sangyo Co., Ltd .: TVB-10), and changes in the viscous torque due to the amount of water added were observed. This measurement result was designated as Comparative Example 1.

  In the same manner, a 50 wt% potassium carbonate aqueous solution was added stepwise and sufficiently stirred. The measurement result was taken as Example 1.

  FIG. 6 shows a graph in which the weight ratio of the added water to the crushed coal weight is expressed on the X axis, and the viscosity torque at that time is expressed as a ratio to the viscosity torque value of the crushed coal without addition on the Y axis.

  When the change of the graph of the comparative example 1 which added water is seen, the value is increasing little by little to about 25 wt%. This is because moisture is absorbed into the pores of the crushed coal and the weight is increased. However, it can be seen that the value sharply decreases when the added amount is around 28 to 29 wt%. This is because the crushed coal adheres to each other, and the crushed coal hardly flows as the rotor rotates. That is, it can be inferred that the moment when the viscous torque sharply decreases is the moment when the surface of the crushed coal becomes wet. A value obtained by measuring the pore volume of the same crushed coal using a specific surface area measuring device is about 0.35 mL / g, and 80 to 90% of the pore volume is filled with moisture.

  On the other hand, when the graph change of Example 1 which added 50 wt% potassium carbonate aqueous solution was seen, when only about 2.5 wt% of water | moisture content was added, the viscosity torque value fell rapidly, and already in this stage The surface is wet. The phenomenon in which the value suddenly increases immediately before is not clearly understood, but it is thought to be due to the high viscosity of the aqueous potassium carbonate solution acting on the rotor.

  From this result, by adding potassium carbonate aqueous solution with high surface tension, the amount of moisture can be greatly reduced, resulting in less heating loss and molding time due to evaporation of moisture during heating molding, and productivity Can be increased.

Examples 2 and 3, Comparative Examples 2, 3, 4, 5
Next, it was analyzed how the water mixed in the adsorbent particles was present inside and on the pores of the crushed coal.

  10 wt%, 23 wt%, 33 wt%, and 45 wt% of water were respectively added to crushed coal having a particle size in the range of 30 to 60 mesh, and the mixture was sufficiently stirred. The crushed charcoal was measured for weight loss (hereinafter referred to as TG) and suggested heat change (hereinafter referred to as DTA) using a thermogravimetric / differential thermal simultaneous analyzer (manufactured by SII: TG / DTA6200). The measurement results were referred to as Comparative Examples 2, 3, 4 and 5.

  By the same method, TG and DTA of crushed coal to which 50 wt% potassium carbonate aqueous solution was added 10 wt% and 44 wt%, respectively, were measured. This measurement result was taken as Example 2. In addition, since it is 50 wt% aqueous solution, the actual water content contained in aqueous solution will be half 5 wt% and 22 wt%.

  As the amount of water added increased, the DTA changed. One peak appeared up to the addition amount of 23%, and two peaks appeared when exceeding 33 wt%. FIG. 7 shows a graph of TG (curve A) and DTA (curve B) of Comparative Example 5 to which 33 wt% of water was typically added.

  From this result, it is considered that there are three states of water. That is, adsorbed water on the pore wall surface of the crushed coal, adsorbed water inside the pores of the crushed coal, and adhering water on the surface of the crushed coal. I will call it. The TG of adsorbed water and adhering water in each state was calculated from this DTA curve, and the weight ratio of the surface adhering water to the total amount of water was determined. The water content was also calculated in Examples 2 and 3 using the same method. These results are shown in Table 1.

  In the case of adding water, even if 23 wt% of water is added, all of the water is absorbed in the pores, and no moisture exists on the surface of the crushed coal. When the amount of water added was further increased, the amount of water adsorbed on the wall surface and pore adsorbed water did not change much, and the amount of water adhering to the surface increased. It can be seen that moisture is present on the surface. This result almost coincides with the result of the above example.

  On the other hand, when the potassium carbonate aqueous solution is added, it can be seen that even when only 5 wt% of water is added, more than half of the water is adhering to the surface of the crushed coal as surface adhering water. Since it exists on the surface without being absorbed by the pores, the amount of water can be significantly reduced by adding a potassium carbonate aqueous solution with a high surface tension. Heating loss due to evaporation and molding time can be reduced, and productivity can be increased.

Example 4 and Comparative Example 6
10 g of water was added to 20 g of crushed charcoal having a particle size in the range of 30 to 60 mesh, and stirred sufficiently. Thereafter, 2.5 g of polyamide particles having a size distribution of 0.08 mm or more and 0.16 mm or less as a particulate thermoplastic resin were mixed and further stirred until the polyamide particles were uniformly mixed. The mixed material was placed in a mold so as to be equal in depth and flat and heated in an oven at 130 ° C. At this time, the temperature sensor was installed so as to be buried in the center of the material, and the temperature change was observed. This result is referred to as Comparative Example 6.

  Next, 1 g of a 50 wt% potassium carbonate aqueous solution was added to 20 g of crushed coal having a particle size in the range of 30 to 60 mesh, and the mixture was sufficiently stirred. Thereafter, 2.5 g of polyamide particles having a size distribution of 0.08 mm or more and 0.16 mm or less as a particulate thermoplastic resin were mixed and further stirred until the polyamide particles were uniformly mixed. The mixed material was placed in a mold so as to be equal in depth and flat and heated in an oven at 130 ° C. At this time, the temperature sensor was installed so as to be buried in the center of the material, and the temperature change was observed. This result is referred to as Example 4.

  Table 2 shows the time required for the temperature of the material to reach 100 ° C. and the time required for forming the gas adsorption filter by melting the polyamide resin.

  In Comparative Example 6 to which water was added, the temperature did not increase moderately, but in the case of an aqueous potassium carbonate solution, the temperature reached 100 ° C. in just 7 minutes from the start of heating, and the polyamide resin dissolved immediately thereafter to form a gas removal filter. It was. By adding potassium carbonate aqueous solution with high surface tension, the amount of water can be greatly reduced, resulting in less heat energy loss due to evaporation of water during heat forming and less time required for heat forming. Can increase the sex.

  By making the surface of the adsorbent particles wet with a small amount of moisture, the mixing with the thermoplastic resin particles is improved, greatly reducing heating loss due to moisture evaporation during thermoforming, and a highly productive gas A method for manufacturing a removal filter can be provided. Moreover, a high-performance gas adsorption filter can be provided by the manufacturing method, and it can be applied to uses such as deodorizing filters of air purifiers and removal of harmful gases such as clean rooms.

DESCRIPTION OF SYMBOLS 1 Gas adsorption filter 2 Adsorbent particle 3 Thermoplastic resin particle 4 Alkali metal salt aqueous solution 5 Vent hole 6 Inside pore 7 Water 8 Needle mold 9 Base part 10 Needle projection 11 Gas adsorption device 12 Blower means 13 Housing

Claims (6)

In a method for producing a gas adsorption filter in which adsorbent particles having gas adsorbing pores and thermoplastic resin particles are mixed and thermoformed, the surface tension is reduced when adsorbent particles and thermoplastic resin particles are mixed. A method for producing a gas adsorption filter, comprising adding an aqueous solution of a surface inactive substance at least 80 mN / m. The method for producing a gas adsorption filter according to claim 1, wherein the interface inert substance is an alkali metal salt, and the solubility of the alkali metal salt in water is at least 30 wt%. 3. The method for producing a gas adsorption filter according to claim 2, wherein the alkali metal salt is potassium carbonate. The method for producing a gas adsorption filter according to any one of claims 1 to 3, wherein the mixing weight ratio of the thermoplastic resin particles to the weight of the adsorbent particles is 5 wt% to 30 wt%. The method for producing a gas adsorption filter according to any one of claims 1 to 4, wherein the adsorbent particles are granular activated carbon. The method for producing a gas adsorption filter according to any one of claims 1 to 5, wherein the thermoplastic resin particles have a melting temperature of 80C to 140C.

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