GB2299034A

GB2299034A - Deodorizing filter

Info

Publication number: GB2299034A
Application number: GB9610033A
Authority: GB
Inventors: Satoru Kadowaki; Ikuo Taguchi; Kunio Okamoto
Original assignee: NipponDenso Co Ltd
Current assignee: Denso Corp
Priority date: 1994-09-14
Filing date: 1995-09-11
Publication date: 1996-09-25
Also published as: JP3728753B2; DE19581244T1; WO1996008303A1; GB9610033D0

Abstract

A flexible porous material formed into a flat plate is used as a porous material (2) carrying adsorbents for adsorbing foul-odor components in gas. Slits (2a, 2b) are alternately formed in front and back sides of this porous material such that the slits are formed to a midway along the thickness in a thickness direction and the porous material is then extended in plane direction to be formed into pleats wherein a bottom portion of a slit becomes an angle portion thereof. When compared with a flat plate-like material, the pleated porous material formed as above has a filtering area remarkably increased to reduce the flow velocity of air passing through the filter, to thereby reduce remarkably the pressure loss. Therefore, since there is generated extra margin in attainment of a target pressure loss, it is possible to increase the volume of adsorbents carried by the porous material, thereby making it possible to improve deodorizing performance remarkably.

Description

DESCRIPTION DEODORIZING FILTER TECHNICAL FIELD The present invention relates to a deodorizing filter to be used to deodorize bad-smelling gas, and more particularly, to a deodorizing filter preferable for adsorbing and removing a bad-smelling component in air introduced into a living space such as the interior of a car.

BACKGROUND ART In recent years, deodorizing filters for removing a bad-smelling component in air are used in various places with a growing demand for living in a comfortable living space. A deodorizing filter obtained by a method disclosed in Laid-Open Japanese Patent Publication No. 61-138511 comprises urethane foam of a three-dimensional meshy construction and active carbon carried therein. In addition, deodorizing filters having various configurations such as honeycomb-shaped one, pleat-shaped one, and the like are used.

These deodorizing filters are different from each other in characteristics thereof such as their pressure losses, longevities, deodorizing performances, costs and the like according to their configurations, constructions, and kinds of adsorbents. Therefore, appropriate deodorizing filters are used according to environments.

The conventional deodorizing filters have, however, the following problems.

That is, generally, a deodorizing filter having a high deodorizing performance has a high pressure loss, whereas a deodorizing filter having a low pressure loss has a low deodorizing performance. The deodorizing filter comprising urethane foam of the three-dimensional meshy construction and active carbon carried therein disclosed in Laid-Open Japanese Patent Publication No. 61-138511 is low in cost, has a long life, and has a high deodorizing performance, but has a high pressure loss. Thus, the usable environment thereof is limited.

In a deodorizing filter disclosed in Laid-Open Japanese Patent Publication No. 62-210030, a large number of through-pores penetrating through top and bottom surfaces of the filter in a ventilation direction is formed to prevent the rise of a pressure loss. However, in the art of this deodorizing filter, the air passing through the pores contacts adsorbent of the filter insufficiently. Consequently, the art has a problem that the deodorizing filter has a low deodorizing effect.

The present invention has been developed in view of the above-described conventional technical problems. It is accordingly an object of the present invention to provide a deodorizing filter having a high deodorizing performance and a low pressure loss.

It is another object of the present invention to provide a deodorizing filter which can be manufactured easily at a low cost.

DISCLOSURE OF THE INVENTION In order to achieve the above objects, the following technical means are adopted in the present invention.

That is, in the present invention, firstly, in a deodorizing filter comprising a porous material carrying adsorbent for adsorbing a bad-smelling component contained in gas, a flexible porous material shaped in a flat plate is used; slits are formed alternately on both upper and lower surfaces of the porous material in a direction of the thickness thereof, with a certain portion uncut along each cut line; and the porous material is extended in a direction perpendicular to the thickness direction thereof to shape the porous material from the flat configuration into a pleat configuration in which a bottom of each slit is formed as a mountain.

The porous material has a great number of cells consisting of pores. The porous base material is treated to communicate the cells with each other by removing films in the cells. That is, the porous material has a construction allowing gas to pass therethrough.

Foam plastic such as urethane foam is preferably used as a material of such a porous material. As the adsorbent, powder active carbon, active carbon fiber, silica gel, zeolite, aluminum hydroxide, and impregnated adsorbent formed by treating the adsorbent with additive can be used.

In a first feature of.the present invention, because the porous material carrying the adsorbent therein is shaped in a pleat configuration, the area of a filtering material of the deodorizing filter is much greater than that of the filtering material of a flat deodorizing filter. Consequently, the flow velocity of gas passing through the filtering material is slow, and the pressure loss of the deodorizing filter is much reduced.

Because the pressure loss of the porous material is allowed to be much smaller than the target allowable pressure loss by shaping the flat porous material in a pleat configuration, amount of adsorbent carried by the porous material can be increased. Accordingly, the deodorizing filter is capable of having a distinguishable deodorizing performance because the porous material is capable of carrying a great amount of the adsorbent and gas flows through the filtering material at a low speed.

Further, paying attention to the fact that the flexible porous material can be easily processed, a simple operation of forming slits in the porous material and extending it into a pleat configuration allows the deodorizing filter to have a high performance and a low pressure loss.

The method of manufacturing the deodorizing filter is very advantageous in reducing the manufacturing cost thereof.

It is preferable to embody the present invention in the following modes to reduce the pressure loss of the deodorizing filter and improve the deodorizing performance thereof, based on the first characteristic of the present invention.

Favorably, the pleat pitch between adjacent mountains of the pleat-shaped porous material is in the range of 3mm 20mm, and more favorably, in the range of 10mm - 15mm.

Favorably, the thickness of the pleat-shaped porous material is in the range of 2mm - 10mm, and more favorably, in the range of 3mm - 8mm.

Favorably, the amount of the adsorbent to be carried by the pleat-shaped porous material is in the range of 0.03g/cc - 0.40g/cc, and more favorably, in the range of 0.10g/cc - 0.20g/cc. The number of cells to be formed on the pleat-shaped porous material is in the range of 6 - 20 per inch.

Secondly, in the deodorizing filter comprising the porous material having a deodorizing function, the porous material is flat plate-shaped, and a large number of concaves is formed in the porous material at an upstream side in the flow direction of gas so that, by the large number of concaves, a pressure loss-reducing portion is partially formed.

The pressure loss-reducing portion reduces the pressure loss partly when gas passes through the deodorizing filter, and is concavely formed in the porous material at the upstream side in the flow direction of gas without the pressure loss-reducing portion penetrating through the porous material.

The pressure loss-reducing portion consisting of the concaves may be wave-shaped in the porous material at the upstream side in the flow direction of gas.

Preferably, the porous material comprises a porous base material and adsorbent carried by the porous base material. Thus, various porous materials and adsorbents can be combined with each other.

Because the porous material is flat, the porous base material may consist of porous glass or a connecting member having a porous construction instead of foam plastic.

In the deodorizing filter of a second characteristic of the present invention, because the pressure loss-reducing portion consisting of the concaves is formed, gas passing through the pressure loss-reducing portion is capable of passing through the deodorizing filter without the pressure loss being reduced greatly. Thus, the pressure loss of the entire deodorizing filter can be decreased.

Further, because the pressure loss-reducing portion is concavely formed in the porous material at the upstream side in the flow direction of gas, without the pressure lossreducing portion penetrating through the porous material, gas containing a bad-smelling component passes reliably through the adsorbent-carried portion in the pressure loss-reducing portion. That is, it does not occur that the bad-smelling component does not pass through the deodorizing filter.

Hence, the deodorizing filter deodorizes the bad-smelling component securely.

Accordingly, the present invention provides the deodorizing filter having a high deodorizing performance and a low pressure loss.

Further, the effect of reducing the pressure loss can be easily changed by adjusting the width or the depth of the concaves formed in the pressure loss-reducing portion, for example.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing a porous material of a deodorizing filter in accordance with a first embodiment of the present invention; Fig. 2 is a partially enlarged sectional view showing a porous base material of the porous material shown in Fig. 1; Fig. 3(a) is an end surface view showing a state in which slits are formed in the porous material of the first embodiment, and Fig. 3(b) is an end surface view showing a state in which the porous material having the slits formed therein is extended in a pleat configuration; Fig. 4 is an explanatory view showing a state in which the porous material, shown in Fig. 3, having the slits formed therein is immersed in adsorbent slurry;; Fig. 5 is a partial sectional view showing an assembling state in which the porous material is installed on an outer frame of the deodorizing filter in accordance with the first embodiment; Fig. 6(a) is a partial sectional view showing another example of an assembling state in which the porous material is installed on the outer frame of the deodorizing filter in accordance with the first embodiment, and Fig. 6(b) is a front view showing a damper of one-touch type; Figs. 7(a) and 7(b) are fragmentary sectional views showing still another example of an assembling state in which the porous material is installed on the outer frame of the deodorizing filter; Fig. 8 is a fragmentary sectional view showing a further example of an assembling state in which the porous material is installed on the outer frame of the deodorizing filter;; Fig. 9 is a graph showing the relationship between a pressure loss and the thickness of a flat porous material as an example of comparison of the present invention; Fig. 10 is a graph showing the relationship between the flow velocity of gas flowing through the porous material and a pressure loss; Fig. 11 is an explanatory view showing specific example of sizes of the pleat-shaped porous material in accordance with the first embodiment; Fig. 12 is a graph showing a toluene gas-removal percentage in the first embodiment and that in the comparison example; Fig. 13 is a graph showing the relationship between the thickness of urethane foam to be used as the porous material and a pressure loss; Fig. 14 is a graph shpwing the relationship between the pleat pitch of pleat-shaped urethane foam as well as the amount of adsorbent carried thereby and a pressure loss;; Fig. 15 is a graph showing the relationship between the thickness of the pleat-shaped urethane foam as well as the amount of adsorbent carried thereby and a pressure loss; Fig. 16 is a graph showing the relationship between the pleat pitch of the pleat-shaped urethane foam as well as the thickness thereof and a pressure loss; Fig. 17 is a graph showing the relationship between the pleat pitch of pleat-shaped urethane foam as well as the amount of adsorbent carried thereby and the toluene gasremoval percentage thereof; Fig. 18 is a graph showing the relationship between the pleat pitch of pleat-shaped urethane foam as well as the thickness thereof and the toluene gas-removal percentage thereof;; Fig. 19 is a graph showing the relationship between the thickness of the pleat pitch of pleat-shaped urethane foam as well as the amount of adsorbent carried thereby and the toluene gas-removal percentage thereof; Fig. 20 is a partially enlarged sectional view showing a porous material of a deodorizing filter in accordance with a fifth embodiment of the present invention; Fig. 21 is a perspective view showing the porous material of the deodorizing filter in accordance with the fifth embodiment of the present invention; Fig. 22 is a partially enlarged sectional view showing a comparison flat porous material, having through-holes formed thereon, to be compared with the porous material of the present invention; Fig. 23 is a partially enlarged sectional view showing a porous material of a deodorizing filter in accordance with a sixth embodiment of the present invention;; Fig. 24 is a partially enlarged sectional view showing a porous base material of a deodorizing filter in accordance with a seventh embodiment of the present invention; and Fig. 25 is a partially enlarged sectional view showing a porous base material of a deodorizing filter in accordance with an eighth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) Figs. 1 through 6 show a deodorizing filter in accordance with a first embodiment of the present invention.

As shown in Figs. 1 and 2, a deodorizing filter 10 of the first embodiment is composed of a porous material 2 having a deodorizing function. The porous material 2 consists of a porous base material 20 and adsorbent held thereby through binder.

As shown in Fig. 2, as the porous base material 20, foam plastic comprising a skeleton 23 and a large number of cells 25 composed of pores formed in the skeleton 23 is used.

Urethane foam is used as the foam plastic in the embodiment.

As the number of the cells 25, any one of 6 cells - 20 cells is selectively formed per inch. Urethane foam used in this embodiment has 13 cells (cell diameter: 2.0=) 25 formed thereon per inch. The porous base material 20 is treated to communicate the cells 25 with each other to remove films between the cells 25 so that gas is allowed to pass through the cells 25.

The adsorbent absorbs a bad-smelling component contained in gas. The adsorbent used in the embodiment is powder active carbon, the diameter of which is 5Hm - 30mum and the specific surface area of which is 1200m2/g. Therefore, while gas is passing from cell to cell, the bad-smelling component contained in the gas is adsorbed by the adsorbent carried by the porous base material 20.

Preferably, the specific surface area of the adsorbent is 800m2 - 2,000m2/g. When the specific surface area of the adsorbent is more than 2,000m2/g, there is a problem that the volumes of pores are so large that the density of the adsorbent itself becomes low and consequently, the density carried by a carrier (porous base material 20) becomes too low. On the other hand, if the specific surface area of the adsorbent is less than 800m2, there is a problem that the adsorbing performance thereof is too low.

As the foam plastic to be used as the porous base material 20 of the porous material 2, it is possible to use polyurethane foam of polyether type, polyurethane foam of polyester type, rubber foam, vinyl foam, polystyrene foam, acrylic foam, polyacetal foam, nylon foam, and the like.

The method of manufacturing the deodorizing filter in accordance with the first embodiment will be described in detail below. First, the flat plate-shaped porous material 2 as shown in Fig. 3 is prepared. Fig. 3 shows the configuration of an end face of the flat plate-shaped porous material 2. Reference letter (h) in Fig. 3 denotes the thickness of the porous material 2. Then, the thickness (h) is set to 20mm, for example.

Then, slits 2a and 2b are alternately formed on the upper and lower surfaces of the porous material 2 in the direction of the thickness (h) thereof, with a certain portion uncut along each cut line. As methods of forming the slits 2a and 2b, a method of cutting the porous material 2 by a metal cutter, and a method of cutting it by laser beams or the like can be used. The width (t) (interval) between the slit 2a and the slit 2b is equal to the thickness of a filter which will be described later. The width (t) is set to 3mm, for example.

The depth of each of the slits 2a and 2b is set to 17mm, for example.

Then, as shown in Fig. 4, the porous material 2 having the slits 2a and 2b is immersed in slurry (A) serving as suspension containing adsorbent (above-described powder active carbon) to allow the porous material 2 to carry the adsorbent therein. Reference letter (B) shown in Fig. 4 denotes a container accommodating the slurry (A).

In preparing the slurry (A), it is preferable to use, with respect to 100 parts (parts by weight, hereinafter abbreviated as merely part) of the powder active carbon, 5 40 parts of emulsion of copolymer of ethylene and vinyl acetate to serve as binder after the slurry (A) is dried and 200 - 500 parts of water.

When the emulsion of the copolymer of ethylene and vinyl acetate (polyvinyl alcohol) is less than five parts, there is a problem that dryness degree is low and consequently, the powder active carbon is not carried by the porous base material 20. On the other hand, when the emulsion of the copolymer of ethylene and vinyl acetate is more than 40 parts, many pores of the powder active carbon are filled therewith.

As a result, the powder active carbon has a deteriorated adsorbing performance.

When water is less than 200 parts, the concentration of the slurry is so high that in impregnating the porous base material 20 with the slurry, the slurry does not penetrate uniformly into the interior of the urethane foam. When water is more than 500 parts, there is a problem that the concentration of the slurry is so low that a small amount of the powder active carbon is carried by the porous base material 20.

Accordingly, in the first embodiment, the slurry (A) is prepared by using 35 parts of the emulsion of the copolymer of ethylene and vinyl acetate (polyvinyl) and 400 parts of water with respect to 100 parts of the powder active carbon.

In addition to the emulsion of the copolymer of ethylene and vinyl acetate, acrylic emulsion, polyvinyl alcohol, polyvinyl acetal, vinyl chloride, copolymer of acrylic and ethylene, copolymer of acrylic-styrene, ether polyurethane resin, polyurethane resin of ether-ester type, polyester-urethane, resin of urethane type, methyl cellulose, hydroxypropylmethyl cellulose (NH4 salt, Na salt), hot-melt polyester, and emulsion of vinyl acetate can be used. These binders have necessary characteristics in connecting the powder active carbon with the porous base material 20 (allowing the powder active carbon to be carried by the porous base material 20).

Then, the porous material 2 impregnated with the slurry (A) is passed between two rollers to squeeze excess slurry therefrom. Thereafter, the porous material 2 is dried for five hours at 1200C to obtain the porous material 2.

Preferably, the porous material 2 carries the dried adsorbent in the range of 0.03g/cc - 0.40g/cc (amount of powder active carbon carried by the porous material 2 per unit volume of carrier). When the adsorbent-carried amount is less than 0.03g/cc, there is a problem that the deodorizing filter has a low bad-smelling component-adsorbing performance, whereas when the adsorbent-carried amount is more than 0.40g/cc, there is a problem that the pressure loss of the deodorizing filter rises excessively high.

Then, as shown in Fig. 3b, the pleat configuration in which bottoms 2c of the slits 2a and 2b are formed as mountains 2d can be formed by extending the porous material 2 carrying the adsorbent at a light force in a direction (C) (see Fig. 3a; perpendicular to direction (h) of thickness).

A pleat pitch (p) shown in Fig. 3 denotes the length between the adjacent pleat-shaped mountains 2d.

Pressure loss and deodorizing performance conforming to a required specification which will be described later can be obtained in the range of a specified product space by adjusting the thickness (h) of the porous material 2, the slit width (t), and the pleat pitch (p) appropriately.

Then, as shown in Fig. 5, the porous material 2 is accommodated in and fixed to an outer frame 2e of a filter with the pleat configuration thereof maintained. Resin is molded to shape the filter outer frame 2e into a rectangular frame configuration (configuration similar to Japanese letter O). An end 2f of the adsorbent-carrying porous material 2 in the pleat direction (right-to-left direction in Fig. 5) and an end surface (end surface in a direction perpendicular to paper of Fig. 5 on which deodorizing filter 10 is drawn) of the pleat-shaped porous material 2 are fixed to the inner surface of the outer frame 2e by fixing means such as bonding. In this manner, the production of the deodorizing filter 10 is completed.The deodorizing filter 10 is removably installed in a ventilation passage (duct) of an air-conditioner for use in a car, an air purifier for use in the car or the like to pass gas (air) containing a bad-smelling component in a direction shown by an arrow (D) of Fig. 5.

As means for fixing the pleat-shaped porous material 2 to the filter outer frame 2e, in addition to the bonding method described with reference to Fig. 5, as shown in Fig. 6, the end 2f of the porous material 2 may be fixed to the filter outer frame 2e by inserting an elastically deformable leg 2h of a damper 2g of one-touch type formed by molding an elastic material (resin, metal or the like) through a hole of the end 2f of the porous material 2 and a hole of the filter outer frame 2e, and locking the damper 2g to the filter outer frame 2e.

Further, as shown in Fig. 7, a supporting wall 2i is formed integrally with the filter outer frame 2e such that the supporting wall 2i is adjacent to the inner surface of the filter outer frame 2e, and the inner side of the mountain of the end 2f of the porous material 2 is inserted to the supporting wall 2i such that the inner side of the mountain is supported by the supporting wall 2i. An auxiliary frame 2j for fixing the mountain of the end 2f of the porous material 2 may be formed to bond right and left ends 2k of the auxiliary frame 2j to the filter outer frame 2e.

Further, as shown in Fig. 8, the end 2f of the porous material 2 may be fixed to the filter outer frame 2e by forming the supporting wall 2i integrally with the filter outer frame 2e such that the supporting wall 2i is adjacent to the inner surface of the filter outer frame 2e, forming a locking claw 2m integrally with the supporting wall 2i at the upper end thereof, inserting the end 2f of the pleat-shaped porous material 2 between the filter outer frame 2e and the supporting wall 2i, and locking the end 2f to the locking claw 2m positioned at the upper end of the supporting wall 2i.

The operation and effect of the deodorizing filter in accordance with the present invention manufactured by the above-described manufacturing method will be described below.

Let it be. supposed that an allowable pressure loss is set to less than 65Pa when the flow velocity of gas is 3m/s in a specified product space of length (200mm) x width (200mm) x thickness (20mm). The required specification is an appropriate level for an air purifier for use in a car.

In order to achieve the required specification by means of a flat porous material (flat urethane foam), the thickness thereof is as shown in Fig. 9. That is, in Fig. 9, the ordinate is a pressure loss Pa and the abscissa is the thickness of the porous material (urethane foam). In order to achieve a target of the allowable pressure loss s 65Pa when the adsorbent-carried amount is 0.065g/cc, it is necessary to set the thickness of the porous material to less than 8.5mm when the number of cells is 10; the thickness thereof to less than 6.5mm when the number of cells is 13; and the thickness thereof to less than 3.5mm when the number of cells is 20.

As described above, when the flat porous material is used, the thickness thereof should be set to a value much smaller than the thickness (20mm) of the specified product space because of the pressure loss. Consequently, the specified product space cannot be fully utilized to improve the deodorizing performance of the deodorizing filter and hence it has a low deodorizing performance.

On the other hand, according to the present invention, since the porous material 2 carrying the adsorbent therein has the pleat configuration, the area of a filtering material of the deodorizing filter is greatly increased. Thus, gas passes through the filtering material at a low velocity and the deodorizing filter has a greatly reduced pressure loss.

Fig. 10 shows the effect of reducing the pressure loss in the present invention. In Fig. 10, the abscissa is the flow velocity of gas passing through the filtering material.

When the flat porous material is used, the pressure loss increases in approximately proportional to the flow velocity of the gas passing through the filtering material as shown by a solid line 1 in a condition that the adsorbent-carried amount is 0.065g/cc, the number of cells is 13, and the thickness of the flat porous material is 5.0mum. Therefore, the pressure loss is 50Pa when the flow velocity of the gas is 3m/s.

On the other hand, when the area of the adsorbentcarrying filtering material of the pleat-shaped porous material 2 according to the present invention is increased three times as great as the area of the filtering material of the flat porous material, the flow velocity of the gas passing through the filtering material of the pleat-shaped porous material 2 is reduced to as small as 1/3, namely, lm/s, and the pressure loss of the filtering material of the pleatshaped porous material 2 is 1OPa which is much smaller than the target allowable pressure loss (65Pa).

As described above, because the pressure loss is allowed to be much smaller than the target allowable pressure loss by forming the porous material 2 having the pleat configuration, the porous material of the present invention is capable of carrying a greater amount of adsorbent than the flat porous material. Accordingly, the deodorizing filter is capable of having deodorizing performance at a very high degree owing to the increase in the adsorbent-carried amount and the reduction in the flow velocity of the gas flowing through the filtering material.

The deodorizing performance of the product of the present invention will be described quantitatively, based on experimental data. Fig. 11 shows an example of a condition of the pleat configuration of the porous material 2. Increased multiple of area of filtering material shown in Fig. 11 means an increased multiple of the area of the pleat-shaped deodorizing filter with respect to that of the flat porous material; and space percentage and urethane percentage mean the percentage of the volume of a space and that of the volume of urethane foam with respect to the specified product space, respectively.

In an experiment to examine the deodorizing performance, pleat-shaped urethane foam having a thickness (t) of 5mm and a pleat pitch (p) of 10mm was used as a representative example.

As a comparison product, a flat-shaped foam was used.

The number of cells of the comparison product was 10, the thickness (t) thereof was 8.5mm, the amount of active carbon carried thereby was 0.06g/cc, and the pressure loss thereof was 65Pa which was the upper limit of the allowable pressure loss.

The pleat configuration of the product of the present invention was as described above. As a condition for making the pressure loss of the product of the present invention equal to that of the comparison product, the number of cells of the product of the present invention was set to 10, and the adsorbent-carried amount of the product of the present invention was increased to 0.15g/cc.

Describing the result of a one-pass gas-removal percentage measured to evaluate the deodorizing performance of the product of the present invention and the comparison product, toluene gas having a concentration at 90ppm was used.

The gas was passed successively therethrough at 150m3/h. The concentration of the gas which has passed therethrough was measured for a certain period of time by using a gas chromatograph (manufactured by Hitachi Manufacturing Co., Ltd.).

Based on values obtained by the measurement, the toluene removal percentage was determined by using the following equation: Toluene removal percentage = [(toluene concentration before passage through products - toluene concentration after passage therethrough) /concentration after passage therethrough] x 100 (%) The result is shown in the graph of Fig. 12 in which the abscissa is a passing time (minutes) of gas and the ordinate is toluene removal percentage. As understood from Fig. 12, it was confirmed that the toluene removal percentage of the product of the present invention was much higher than that of the comparison product.

As described above, the product of the present invention utilizes the given specified product space effectively, thus satisfying demands for a reduced pressure loss and improving its deodorizing performance.

Further, according to the manufacturing method of the first embodiment, utilizing the characteristic of urethane foam (that is, it can be processed easily, it is flexible, it has a three-dimensional meshy construction, it is capable of carrying adsorbent easily, and it collides with gas at a high collision efficiency and is thus superior in its deodorizing performance), the deodorizing filter having a high deodorizing performance and a low pressure loss can be easily obtained by performing easy operations of forming slits in the urethane foam and extending it to the pleat configuration.

A preferable numerical range of the pleat-shaped porous material 2 which characterizes the present invention will be described below. Fig. 13 shows the relationship between the pressure loss of the porous material 2 made of urethane foam and the thickness thereof by indicating the number of cells as a parameter. In the practically usable region (thickness t < 10mm) of the thickness of the porous material 2, porous materials 2.having 8, 10, and 13 cells show the same degree of pressure loss. Thus, it is understood that any one of 8, 10, and 13 cells can be used. As the experimental condition indicated in Fig. 13, the flow velocity of gas which passed through the porous materials 2 made of urethane foam was 3m/s.

Fig. 14 shows the relationship between the pleat pitch (p) as well as the adsorbent-carried amount and the pressure loss. As a condition of an experiment shown in Fig. 14, the thickness (t) (slit width) was fixed to 5mm; the number of cells was fixed to 10; and the flow velocity of gas was set to 3m/s.

In Fig. 14, the appropriate range of the pleat pitch (p) is lOmm - 15mm and the appropriate range of the adsorbentcarried amount is less than 0.15g/cc, in order to allow the pressure loss to be less than the greatest target pressure loss (65Pa).

Fig. 15 shows the relationship between the thickness (t) of the pleat-shaped urethane foam as well as the adsorbent-carried amount and the pressure loss. As a condition of an experiment shown in Fig. 15, the pleat pitch (p) was fixed to 10mm; and the number of cells was fixed to 10; and the flow velocity of the gas was set to 3m/s.

Fig. 15 indicates that the appropriate range of the thickness (t) is less than 5mm and the appropriate range of the adsorbent-carried amount is less than 0.15g/cc to allow the pressure loss to be less than the greatest target pressure loss (65Pa).

Fig. 16 shows the relationship between the pleat pitch (p) of the pleat-shaped urethane foam as well as the thickness (t) thereof and the pressure loss. As a condition of an experiment shown in Fig. 16, the number of cells was fixed to 10; the adsorbent-carried amount is fixed to 0.16g/cc, and the flow velocity of the gas was set to 3m/s.

Fig. 16 indicates that the appropriate range of the thickness (t) is less than 5mm and the appropriate range of the pleat pitch (p) is 10mm - 15mm in order to allow the pressure loss to be less than the greatest target pressure loss (65Pa).

In the experimental data shown in Fig. 14 through Fig.

16, description has been made about the case in which the target pressure loss is set to 65Pa or less. Needless to say, when the target pressure loss changes, the appropriate ranges of the thickness (slit width (t)), the pleat pitch (p), and the adsorbent-carried amount change. Consequently, the deodorizing performance of the porous material changes according to the change of the appropriate range.

The change of the deodorizing performance of the porous material according to the changes of the pleat configuration and the adsorbent-carried amount will be described with reference to Figs. 17 through 19. Fig. 17 shows one-pass gas removal percentage of the pleat-shaped porous material 2 (urethane foam) in the elapse of 15 minutes past after gas starts to pass therethrough. More specifically, Fig. 17 shows the change of the toluene removal performance of the porous material 2 with the change of the pleat pitch (p) and the change of the adsorbent-carried amount. As an experimental condition, the thickness (t) was set to 5mm, the number of cells was set to 10, and the flow velocity of gas was set to lm/s.

Fig. 18 shows the change of the toluene removal performance of the porous material 2 with the change of the pleat pitch (p) and the change of the thickness (t). As an experimental condition, the adsorbent-carried amount was set to 0.15g/cc; the number of cells was set to 10, and the flow velocity of the gas was set to lm/s.

Fig. 19 shows the change of the toluene removal performance of the porous material 2 with the change of the adsorbent-carried amount and the change of the thickness (t).

As the experimental condition, the pleat pitch (p) was 10mm, the number of cells was 10, and the flow velocity of the gas was lm/s.

The preferable mode of the pleat-shaped deodorizing filter in accordance with the present invention is summarized by numerical ranges as follows: (1) Preferably, the number of cells per inch is in the range of 6 - 20. That is, as shown in Fig. 13, to prevent the rise of the pressure loss, preferably, the upper limit of the number of cells is set to 20. When the number of cells is six or less, the area of the outer surface of the porous material made of urethane foam is so small that the deodorizing performance thereof is low.

(2) Preferably, the pleat pitch (p) is in the range of 3mm - 20mm. That is, favorably, the upper limit of the pleat pitch (p) is 20mm as shown in Figs. 14 and 16 to prevent the rise of the pressure loss and improve the deodorizing performance as shown in Figs. 17 and 18. Favorably, the lower limit of the pleat pitch (p) is 3mm in practical use to prevent the rise of the pressure loss, as shown in Figs. 14 and 16.

More favorably, the pleat pitch (p) is in the range of lOmm - 15mm as indicated by the experimental results shown in Figs. 14 and 16.

(3) Favorably, the thickness (t) is in the range of 2 - lOmm. That is, in order to suppress the rise of the pressure loss, favorably, the upper limit of the thickness (t) is 10mm in practical use, as shown in Fig. 13. Favorably, the lower limit of the thickness (t) is 2mm in practical use, based on the experimental result of the toluene-removal performance shown in Fig. 19.

More favorably, the thickness (t) is set to less than 8mm based on the experimental result shown in Fig. 15.

Favorably, the lower limit of the thickness (t) is 3mm to secure a preferable toluene-removal performance shown in Figs.

18 and 19.

(4) As the adsorbent-carried amount per unit volume of the carrier, 0.03g/cc - 0.40g/cc is allowed in practical use.

Of the above range, the range of 0.10g/cc - 0.20g/cc is favorable. That is, in order to suppress the rise of the pressure loss, favorably, the upper limit of the adsorbent-carried amount is 0.40g/c in practical use. More favorably, the upper limit of the adsorbent-carried amount is 0.20g/cc based on the experimental results shown in Figs. 14 and 15.

Favorably, the lower limit of the adsorbent-carried amount is 0.03g/cc in practical use to secure a favorable deodorizing performance. More favorably, based on the experimental results shown in Figs. 17 and 19, the lower limit of the adsorbent-carried amount is 0.1Og/cc.

(Second Embodiment) In the first embodiment, the active carbon used as the adsorbent is normal active carbon to which additives are not added. In the second embodiment, instead of the additiveunadded normal active carbon, additive-added active carbon is used. The additive-added active carbon is carried by the porous material 2, and then, the pleat-shaped porous material 2 is formed by a method similar to that of the first embodiment.

Of the additives, as additives applicable to acid gas, one of the following compounds was used: Organic silicon compounds such as 3-aminopropyltrihydrosilane, aminopropyltriethoxys ilane, y -glye idxypropyltrimethoxys il ane , N-ss(aminoethyl)-y-aminopropyltrimethoxysilane, dimethyltrimethyl-sylylamine, N-( B-aminoethyl) -y-aminopropyl- trimethoxysilane; or aniline compounds such as aniline phosphate, aniline hydrochloride or the like; or pyridine, toluidine, benzenamine chloride, anthranilic acid.

As additives applicable to basic gas, one of the following compounds was used: L-tartaric acid, salicylic acid, picolinic acid, benzoic acid, phthalic acid, L-glutamic acid, succinic acid, maleic acid, citric acid, gluconic acid, malic acid, fumaric acid, glutaric acid, itaconic acid, pimelic acid, adipic acid, glyceric acid, gallic acid.

In addition, compounds of metallic salt of cobalt, copper, manganese, chrome, iron, nickel, titan or the like can be used as the additive.

Except the use of the additive-added active carbon, a deodorizing filter was manufactured in a manner similar to that of the first embodiment. In the second embodiment, the deodorizing filter comprising the additive-added active carbon applicable to acid gas has an remarkably improved performance in deodorizing bad-smelling gas such as hydrogen sulfide, acetaldehyde or the like. Further, the deodorizing filter comprising the additive-added active carbon applicable to basic gas has also an remarkably improved performance in deodorizing bad-smelling gas such as ammonia or the like. In other points, the deodorizing filter according to the second embodiment has an effect similar to that of the first embodiment.

(Third Embodiment) Instead of powder active carbon used in the first embodiment, active carbon fiber, silica gel, zeolite, aluminum hydroxide, sepiolite or the like is used as adsorbent in the third embodiment.

Because the active carbon fibers are long, they do not enter uniformly into the interior of the porous material 2.

Thus, preferably, they are used in a pulverized state.

According to the third embodiment, the active carbon fibers have more pores than the powder active carbon. Thus, the toluene-removal percentage of the active carbon fibers is higher by about 20% than that of the powder active carbon of the first embodiment. In other points, the deodorizing filter according to the third embodiment has an effect similar to that of the first embodiment.

(Fourth Embodiment) In the first embodiment, the adsorbent is prepared to the slurry, then the porous material (urethane foam) 2 carries the adsorbent in the slurry. In the fourth embodiment, instead of the adsorbent-carrying method of the first embodiment, it is possible to use "dry carrying method" of attaching binder to the skeleton 23 of the porous material 2 and then attaching the adsorbent to the surface thereof by means of the binder.

The deodorizing filter in accordance with the fourth embodiment will be described in detail below.

(1) Binder-attaching process The same compounds as those used in the first embodiment may be used as the binder in the fourth embodiment. Not only water-soluble compounds, but also oily ones, for example, special modified polymer or the like may be used. In the fourth embodiment, as the material of the binder, emulsion of copolymer of ethylene and vinyl acetate is used.

As binder-attaching methods, it is possible to use a spray method of attaching the binder of a spray liquid to the porous material (urethane foam) 2 extended in a pleat configuration by means of a sprayer, roller method of attaching the binder to the porous material (urethane foam) 2 extended in a pleat configuration by means of a roller, or impregnation method of impregnating the binder to the porous material 2 extended in a pleat configuration by immersing the porous material 2 in a container accommodating binder slurry.

In the impregnation method, similarly to the method shown in Fig. 4, the flat porous material 2 may be immersed in the binder slurry before it is extended into a pleat configuration. Further, unnecessary amount of binder is squeezed to remove, then, air is blown to the porous material 2 to prevent that the porous material 2 is clogged by the binder.

(2) Adsorbent-carrying process The particle size of powder active carbon to be used as the adsorbent is preferably in the range of 20 - 50 meshes.

If the particle size of powder active carbon is less than 20 meshes, unfavorably, the porous material 2 has a high pressure loss. If the particle size thereof is more than 50 meshes, the porous material 2 carries a small amount of active carbon and unfavorably has a low deodorizing performance.

As the adsorbent-carrying method, the porous material 2 to which the binder has been attached is fixed, with the porous material 2 extended in a pleat configuration; the powder active carbon is dispersed on the upper surface of the pleat-shaped porous material 2; and the dispersed powder active carbon is pressed against the porous material 2 by a roller to force it into the interior thereof.

As the adsorbent-carried amount, the range of 0.03g/cc - 0.40g/cc is practically usable but of the above range, the range of 0.10g/cc - 0.20g/cc is favorable in view of the suppression of the increase in the pressure loss and the improvement of the deodorizing performance.

(Fifth Embodiment) In all of the first embodiment through the fourth embodiment, the pleat-shaped porous material 2 is formed to reduce its pressure loss and improve its deodorizing performance. In the fifth embodiment, as shown in Figs. 20 and 21, a large number of cylindrical concaves 32 is formed on a surface of the flat porous material 2 at the upstream side in the flow direction of gas to allow the concaves 32 to form a partial pressure loss-reducing portion so that the deodorizing filter has a low pressure loss.

Similarly to the first embodiment through the fourth embodiment, the porous material 2 of the fifth embodiment comprises the porous base material 20 and adsorbent carried thereby through binder. The material of the binder, the material of the adsorbent, and the adsorbent-carrying method are also similar to those of the first embodiment through the fourth embodiment.

As shown in Fig. 2, as the porous base material 20, the urethane foam comprising the skeleton 23 and the large number of cells 25 formed in the skeleton 23 is used. As the number of the cells 25, urethane foam of fifth embodiment has 13 cells (cell diameter: 2.0mum) 25 formed therein per inch.

The porous base material 20 is treated to communicate the cells 25 with each other to prevent films from being formed in the cells 25. Thus, while gas is passing through from cell to cell, a bad-smelling component in the gas is adsorbed by the porus base material 20.

As shown in Fig. 21, the diameter (D) of each of the concaves 32 is 5mm about twice as large as that of the cell 25. In the interval between the adjacent concaves 32, the lengthwise (P) is 6mm and the widthwise (Q) is 9mm to arrange the concaves 32 regularly lengthwise and widthwise.

The flat porous material 2 having the concaves 32 formed therein is immersed in adsorbent slurry to allow the porous material 2 to carry the adsorbent (powder active carbon) therein. The amount of the powder active carbon carried by the porous material 2 is 0.05g/cc per unit volume of the carrier.

In the deodorizing filter 10 of the fifth embodiment, the gas passing through the concaves 32 formed as the pressure loss-reducing portion passes through the deodorizing filter without its pressure being reduced greatly. Therefore, the entire pressure loss can be allowed to be small. Further, the gas does not pass through the concaves 32 without contacting them, but passes through the bottoms thereof and the bad smelling component contained therein is adsorbed by the powder active carbon carried by the porous material 2. Accordingly, the deodorizing filter 10 of the fifth embodiment maintains a high deodorizing performance and has a low pressure loss.

Incidentally, when through-holes 3 are formed in the flat porous material 2 of a comparison example shown in Fig.

22, a part of bad-smelling component of gas passes through the through-holes 3 without being adsorbed by the adsorbent.

Consequently, the porous material 2 has a reduced deodorizing performance.

Further, because the pressure loss-reducing portion of the fifth embodiment is concavely formed, the porous material 2 has an effect of easily adjusting the pressure loss and deodorizing performance depending on the configuration or the like (depth of concave, diameter thereof, and sectional configuration thereof) of the concaves 32.

In the fifth embodiment, as a method of forming the concaves 32 serving as the pressure loss-reducing portion, holes are formed in the porous material 2 in the thickness direction with a certain portion left at one end thereof as shown in Fig. 20, but it is possible to form through-holes through the porous material 2 in the thickness direction and a thin flat porous material is formed on one surface of the porous material 2 to close one side of each of the throughholes. Needless to say, adsorbent is also carried by the thin flat porous material.

(Sixth Embodiment) The characteristic of the sixth embodiment is that instead of the concaves 32 of the fifth embodiment, as shown in Fig. 23, concaves 33 wave-shaped in section are formed in the porous material 2. The porous material 2 according to the sixth embodiment has an effect similar to that of the fifth embodiment owing to the formation of the pressure lossreducing portion consisting of the wave-shaped concaves 33.

Further, the pressure loss and deodorizing performance of the porous material 2 can be easily adjusted depending on the configuration of the wave-shaped concaves 33.

(Seventh Embodiment) In the seventh embodiment, instead of urethane foam used as the porous base material 20 of the first through sixth embodiments, a connecting member 204 having a porous construction made of porous ceramic is used, as shown in Fig. 24. The connecting member 204 having the porous construction has a large number of gas-flowable voids 242 surrounded with connecting particles 241. The seventh embodiment has an effect similar to that of the fifth and sixth embodiments by forming the flat connecting member 204 having the porous construction and forming the cylindrical concaves 32 and the wave-shaped concaves 33 thereon. Further, the porous material 2 has an improved deodorizing performance and a long life by composing the connecting member 204 of a material (for example, metal oxide) having a bad-smelling component-adsorbing effect.In addition, the connecting member 204 having such a material provides an effect of improving the strength of the deodorizing filter and the heat-resistant property.

The connecting member 204 made of porous ceramic and a granular substance connected thereto with binder has an effect similar to the above effect.

(Eighth Embodiment) In the eighth embodiment, instead of the connecting member 204 having the porous construction, as shown in Fig.

25, a porous glass 205 is used as the porous base material 20.

The porous glass 205 has a large number of gas-flowable pores 251. In other points, the porous glass 205 is similar to the effect of the seventh embodiment.

In the eighth embodiment, similarly to the seventh embodiment, because the porous glass itself has adsorbing effect, it provides an effect of enhancing deodorizing effect.

In addition, the porous glass is effective for improving the strength of the filter and heat-resistant property.

FIELD OF INDUSTRIAL APPLICATION According to the present invention, a deodorizing filter having deodorizing performance for deodorizing badsmelling gas at a low pressure loss is provided. Accordingly, the deodorizing filter can be preferably used in a ventilation duct of an air-conditioning apparatus, for example, in the interior such as a ventilation duct of the air-conditioning apparatus for use in a car, thus deodorizing a bad-smelling component contained in air passing through the air-conditioning apparatus.

Claims

1. A deodorizing filter having a porous material carrying adsorbent for adsorbing a bad-smelling component contained in gas, the filter comprising: a flexible porous material shaped in a flat plate; slits formed alternately on both upper and lower surfaces of the porous material in a direction of the thickness thereof, with a certain portion uncut along each cut line; and the porous material being extended in a direction perpendicular to the thickness direction thereof to shape the porous material from the flat configuration into a pleat configuration in which a bottom of each slit is formed as a mountain.

2. The deodorizing filter according to claim 1, wherein the porous material includes a foam plastic.

3. The deodorizing filter according to claim 2, wherein the foam plastic includes a urethane foam.

4. The deodorizing filter according to any one of claims 1 through 3, wherein a pleat pitch between adjacent mountains of the pleat-shaped porous material is in the range of 3mm 20mm.

5. The deodorizing filter according to any one of claims 1 through 3, wherein a pleat pitch between adjacent mountains of the pleat-shaped porous material is in the range of lOmm 15mm.

6. The deodorizing filter according to any one of claims 1 through 5, wherein a thickness of the pleat-shaped porous material is in the range of 2mm - loom.

7. The deodorizing filter according to any one of claims 1 through 5, wherein a thickness of the pleat-shaped porous material is in the range of 3mm - 8mm.

8. The deodorizing filter according to any one of claims 1 through 7, wherein an amount of the adsorbent to be carried by the pleat-shaped porous material is in the range of 0.03g/cc - 0.40g/cc.

9. The deodorizing filter according to any one of claims 1 through 7, wherein an amount of the adsorbent to be carried by the pleat-shaped porous material is in the range of O.lOg/cc - 0.20g/cc.

10. The deodorizing filter according to any one of claims 1 through 9, wherein the number of cells to be formed in the pleat-shaped porous material is in the range of 8 - 20 per inch.

11. A method of manufacturing a deodorizing filter comprising the steps of: shaping a flexible porous material in a flat configuration; forming slits alternately on both upper and lower surfaces of the porous material in a direction of the thickness thereof, with a certain portion uncut along each cut line; carrying adsorbent for adsorbing a bad-smelling component contained in gas by the porous material having the slits formed therein; and extending the porous material in a direction perpendicular to the thickness direction thereof to shape the porous material from the flat configuration into a pleat configuration in which a bottom of each slit is formed as a mountain.

12. A method of manufacturing a deodorizing filter comprising the steps of: shaping a flexible porous material in a flat configuration; forming slits alternately on both upper and lower surfaces of the porous material in a direction of the thickness thereof, with a certain portion uncut along each cut line; extending the porous material in a direction perpendicular to the thickness direction thereof to shape the porous material from the flat configuration into a pleat configura tion in which a bottom of each slit is formed as a mountain; and carrying adsorbent for adsorbing a bad-smelling component in contained air by the pleat-shaped porous material.

13. A deodorizing filter comprising: a porous material having a deodorizing function, the filter being made of a porous material and flat plate-shaped; and a large number of concaves formed in the flat porous material at an upstream side in a flow direction of gas, the concaves serving as a partial pressure loss-reducing portion.

14. The deodorizing filter according to claim 13, wherein the porous material includes a porous base material and adsorbent carried by the porous base material.

15. The deodorizing filter according to claim 14, wherein the porous base material includes one of foam plastic, porous glass and a connecting member having a porous construction.