JPH1043530A - Air purifying filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain low pressure drop even under high wind velocity and excellent dust collecting performance by forming and processing a polyurethane foam having a three-dimensional netlike skeleton structure with fine cells on one side or both sides into a pleat state as an air purifying filter. SOLUTION: A base material 1 is formed from the polyurethane foam having the three dimensional netlike skeleton structure and is formed and processes into the pleat state using an according pleating machine. Since the pleating results in the increase of contact area with the air layer, low pressure drop and excellent dust collecting performance are attained. A non-solvent type binder layer is applied on the surface of the porous skeleton structure of the polyurethane foam and adsorbent particles are stuck to the binder layer so that a part of the adsorbent particles is in contact with the binder layer and the residual is exposed. The air purifying filter obtained in this way has the excellent performance even under the high wind velocity such as in a car air conditioner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air purifying filter which is suitable for use at a high wind speed, such as an air purifier, a room air conditioner, and particularly a vehicle air conditioner (car air conditioner).

[0002]

2. Description of the Related Art A pleated paper filter having a dust collecting function and / or a deodorizing function is known as a means for suppressing pressure loss and obtaining high dust collecting performance and high deodorizing performance. . By processing it into a pleated shape,
The surface area of the filter was increased. As a paper-like filter, a non-woven fabric or a non-woven fabric obtained by subjecting a non-woven fabric or a fiber to a charging treatment is known.
It is possible to collect fine dust of submicron order by Coulomb force, and even if it has a low basis weight, it is superior in collecting performance to untreated nonwoven fabric.

[0003]

Under the conditions of use at a high wind speed, such as a car air conditioner, mechanical collection (inertia, collision) is more important than Coulomb force. The effect was not fully exploited. Under high wind speed conditions, the higher the contact efficiency with dust, the higher the dust collection performance can be obtained.However, in the case of fibrous or paper-like materials such as nonwoven fabrics, the pressure loss of the base material itself is high, Even if the surface area is increased by pleating, there is a limit to the pressure loss reduction effect, and when adding a deodorizing function, the pressure loss is further increased, and in applications where low pressure loss is required, sufficient dust collection performance and Deodorizing performance was not obtained. In addition, since mechanical collection is mainly performed for coarse dust having a size of 5 μm or more, the charging treatment is not effective for applications at high wind speed and for coarse dust.

Accordingly, an object of the present invention is to provide an air purifying filter capable of obtaining high dust collecting performance and high deodorizing performance even under a high wind speed such as a car air conditioner.

[0005]

In order to achieve the above-mentioned object, the present invention comprises a pleated polyurethane foam having a three-dimensional reticulated skeleton structure with fine cells on one or both sides. ADVANTAGE OF THE INVENTION According to this invention, even under a high wind speed like a car air conditioner, pressure loss can be reduced and high dust collection performance can be obtained.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment of the first invention shown in FIG. 1, a side view of a base material 1 formed into a pleated shape by an accordion pleating machine is shown. It consists of a polyurethane foam having a fine three-dimensional network skeleton structure of cells. The three-dimensional networked skeleton structure refers to a regular dodecahedral skeleton structure formed by a polyurethane resin.

A base material 1 is formed of a polyurethane foam having a three-dimensional network structure having a thickness of 5 mm and a cell number of 50 _PPI and having a three-dimensional network structure. The base material 1 is formed with an accordion pleated machine to have a peak height h of 20 mm and a pitch p of 10 mm. , The insertion magnification is 4
The doubled substrate is referred to as Example 1, the base material 1 itself (flat shape) before being formed into a pleated shape is referred to as Comparative Example 1, and the polypropylene nonwoven fabric is formed into a pleated shape (peak height 1).
Pressure loss and dust collection efficiency were compared using, as a reference example, a sample having a size of 5 mm, a folding ratio of 4.4 times, and a pitch of 7 mm. The results were as shown in Table 1. Here, the "folding ratio" means that the length of the pleated shape is
The case of a quarter of the length of the base material 1 before the forming process is referred to as “folding magnification 4 times”.

[0008]

[Table 1]

In the measurement of the pressure loss in Table 1 above, the test filter 10 is set in the wind tunnel 11 as shown in FIG. 2, the wind speed is given by the fan 12, and the pressure upstream and downstream of the filter 10 at a wind speed of 3 m / sec. The difference was measured with the pressure loss meter 13. Reference numeral 14 in FIG.
Reference numeral 5 denotes a control plate, and reference numeral 16 denotes a particle counter. To measure the dust collection efficiency, the test filter 10 was set in the wind tunnel 11, the wind speed was given by the fan 12, and the upstream and downstream of the filter 10 at a wind speed of 3 m / sec.
The particle concentration of air dust having a particle diameter of not less than μm (pieces / 0.01 ft ³ ) was counted by the particle counter 16. Indoor dust was used as the measurement dust. The size of the opening of the wind tunnel 10 at the location of the test filter 10 was 250 mm × 250 mm.

The pleated product of Example 1 is more pleated than the flat product of Comparative Example 1.
Since the contact area with the air layer increases, low pressure loss can be achieved and high dust collection performance can be realized. Further, since the base material 1 is a polyurethane foam having a three-dimensional network skeleton structure, substantially the same dust collection performance can be realized with low pressure loss as compared with the reference example.

The air permeability of the substrate 1 is determined by the JI as shown in FIG.
The amount of passing air (cm ³ / cm ² / sec) by a Fragile type testing machine based on SL 1004-1972 (testing method for cotton fabric) is 150 when measured at a thickness of 10 mm.
As described above, it is preferable to use those having a value of 250 or more. 3, the test filter 10 is mounted on the upper end of a cylinder 17, a blow fan 18 is provided on the lower end of the cylinder 17, and an air hole 19 is provided in the middle of the cylinder 17.
Is installed, and the inclination type barometer 21 is adjusted so as to indicate a pressure of 1.27 cm of water column, and the pressure indicated by the vertical type barometer 22 at that time and the type of the air hole 19 used are determined. Is used to determine the amount of air passing through the test filter 10. The number of cells is 6 to 80
_PPI (poresper inch), preferably 9 to 50 _PPI .

Not only a single layer of the base material 1 but also a polyurethane foam having an antibacterial function or a polyurethane foam which has been subjected to adhesive processing to improve the dust collection performance is laminated on the above-described base material 1 or the number of cells. Can be formed into a pleated shape by laminating polyurethane foams of different types. FIG. 4 shows a preferred embodiment of the second invention, in which a non-solvent binder applied to the surface and inside of a porous skeleton structure of a polyurethane foam having a fine three-dimensional network skeleton structure on one or both sides of a cell. Layer and adsorbent particles partially contacted and fixed to the binder layer and exposing the remainder, and the adsorbent particles are at least 1/50 of the average inter-skeleton distance of the polyurethane foam and 1.5 minutes or less. The substrate 2 having an average particle size of 1 or less is formed into a pleated shape. In the illustrated embodiment, the thickness t of the substrate 2 is 2.5
mm, the pitch p was 10 mm, and the peak height h was 20 mm. When the average particle size of the adsorbent particles is 1 / 1.5 (67%) or more of the average inter-skeleton distance (pore diameter) of the polyurethane foam, even if the adsorbent particles are sprayed from the surface, the porous body has a skeleton structure. It is difficult to penetrate inside,
Most of the adsorbent particles adhere to the vicinity of the surface, and the adhesive force is weak, so that the adsorbent particles that have adhered easily fall off. This is thought to be because the area of the adhering portion with the polyurethane foam becomes relatively smaller than the size of the adsorbent particles. When the average particle size of the adsorbent particles is 1/50 (2%) or less of the pore size, the amount of adsorbent particles adhering to the polyurethane foam is significantly reduced. This is presumably because the fine adsorbent particles cover the binder applied to the polyurethane foam thinly and do not adhere any more, so that the absolute amount of fixation is reduced. As a result, the adsorption capacity of the entire adsorbent particles is reduced. The adsorbent particles have a pore diameter of 1/50 or more,
The value of 1 / l or less is important as a condition for adsorbing particles to be dispersed and fixed to the inside of the porous body, and also for improving the adsorbing ability. In addition, the air permeability is maintained and the absolute amount of adsorption is increased. Is considered, the average particle size is defined as 1
It is preferable that the value be not less than 1/0 and not more than 1/2. Further, as for the particle size distribution of the adsorbent particles, one having 95% by weight or more of the average particle size is 1/5 to 5 times, preferably 1/2 to 2 times the average particle size.

As shown in FIG. 3, the air permeability of the polyurethane foam serving as the base of the substrate 2 is JIS L1004.
It is preferable to use a material having a passing air volume (cm ³ / cm ² / sec) of at least 150, preferably at least 250 as measured with a 10 mm thickness by a Frazier type testing machine based on -1972 (testing method for cotton fabric). The number of cells is 6 to 80
_PPI , preferably 9-50 _PPI .

Activated carbon, activated clay,
Adsorbent particles that have been put into practical use, such as activated alumina and powdered silica gel, can be arbitrarily selected and used according to the purpose of use.

As the non-solvent-based binder, various ones can be appropriately selected and used. However, those having a strong adhesive force and hardly causing clogging of the pores of the adsorbent particles are preferable. A non-solvent binder having a low volatile component, that is, a solid content of 30% by weight or more, preferably 50% by weight or more is selected. Specifically, NC
An O-excess urethane prepolymer (more NCO relative to the urethane resin component), more preferably an MDI (methylene diisocyanate) based urethane prepolymer is used. MDI-based prepolymer is more TDI
(Tolylene diisocyanate) Free isocyanate is less likely to be generated than those based on tolylene diisocyanate, adsorption to adsorbent particles is small, and there is little problem in terms of hygiene in the production process. When the urethane prepolymer in excess of NCO is used as a binder, if the viscosity is too high as it is, a minimum amount of an organic solvent is added and applied. Is advantageous because it facilitates workability and prevents solvent adsorption. The non-solvent-based binder is applied by, for example, a method of impregnating the impregnating tank with the polyurethane foam and then squeezing out the excess binder with a roll, a method of applying the surface to the surface with a spray or a roll coater, and then squeezing with a roll and spreading the inside. In order to attach the adsorbent particles to the polyurethane foam coated with the binder in advance in this way, adsorbent fluidized bed immersion, that is, a method of immersion impregnation while applying vibration to the adsorbent, powder spray,
Alternatively, a method such as falling through a sieve is used. When a method using powder spraying or sieving is used, uniform adhesion can be performed by spraying or dropping the adsorbent particles from both sides of the polyurethane foam by a method such as inverting the polyurethane foam. By vibrating the polyurethane foam during and / or after adsorbent particle attachment, penetration of the adsorbent particles into the inside of the polyurethane foam and reliable attachment to the polyurethane foam skeleton can be assisted. Furthermore, after adsorbent particles adhere,
Passing between one or more sets of rolls and light compression may help adhere to the polyurethane foam backbone. At this time, it is appropriate that the roll interval is 90 to 60% of the thickness of the polyurethane foam.

In order to solidify the non-solvent binder,
What is necessary is just to use the method suitable for each binder,
When a urethane-based prepolymer is used, curing can be performed with heated steam, so that the process is simple and a large fixing force is obtained. Polyurethane foam with an average inter-skeleton distance (pore diameter) of 2.5 mm (15 mm thick x 100 mm x 100 m
m, passing air volume 300 or more, weight 4.2g)
This was impregnated and coated with a non-solvent binder (a prepolymer of carbodiimide-modified MID and polypropylene glycol) of the same weight as the foam. The average particle size is 2.2mm
(Comparative example 2), 1.5 mm (base material example 1), 0.6 mm (base material example 2), 0.3 mm (base material example 3), 0.1 mm (base material example 4), 0.02 mm ( The coconut shell activated carbon of Comparative Example 3) was sprayed with a powder spray, and further sprayed from the back surface in the same manner.
Next, the non-adhered activated carbon was sieved off by vibration and the adhesion of the adhering activated carbon was strengthened. For Comparative Examples 2 and 3 and Base Materials Examples 1 to 4, measurement of activated carbon adhesion amount (g), determination of internal adhesion and adhesion, and measurement of adsorption capacity were performed. The adsorption capacity was measured based on the equilibrium adsorption amount of benzene based on JIS K1474-1975 (test method for activated carbon) (see FIG. 5). The prototype sample was cut into 15 mm × 15 mm × 15 mm dice, placed in a U-tube, and air containing benzene vapor was passed at a rate of 2 liters / min. The increased weight of 25 cc) was taken as the equilibrium adsorption amount. In FIG. 5, A ₁ and A ₂ denote temperature control snake tubes, B _{1 to} B ₃ denote gas cleaning bottles (each 250 ml), C denotes a mixing bottle, and D denotes a U-tube for an adsorption test. .
E is a three-way cock, F ₁ is a flow meter for solvent vapor generating air, F ₂ is a flow meter for dilution air, N is a constant temperature bath or a constant temperature water bath, H is a surplus gas outlet, I is a dry air inlet, and J is an exhaust. The ports, K ₁ and K ₂ indicate gas flow rate control cocks, and L indicates benzene. The results are as shown in Table 2 below.

[0017]

[Table 2]

When the average particle size of activated carbon is 2.2 mm (particle size / pore diameter ratio: 88%) (Comparative Example 2), the amount of activated carbon attached is large,
Although the adsorbing ability was high, the one that adhered to the inside of the foam skeleton was small, and the one that adhered near the foam surface layer was mostly weak in adhesion. In addition, the activated carbon has an average particle size of 0.1.
In the case of 02 mm (particle diameter / pore diameter ratio 0.8%) (Comparative Example 3)
However, since the fine activated carbon particles covered the binder thinly, the amount of adhesion was small, and the improvement of the adsorption capacity was not so much observed. Those having an average particle diameter / pore diameter ratio in the middle (Examples of base materials 1 to 4) showed good results in which the adhesion amount and the adsorption capacity were balanced.

A polyurethane foam having a cell number of 16 _PPI and a thickness of 2.3 mm is impregnated with an acrylic emulsion binder (solid content: 50%) to a concentration of 27 g / liter and dried, and has an adsorption surface area of 1500 m ² / g. In order to form the base material 2 shown in FIG. 4 in which coconut shell activated carbon having a particle size of 60 mesh is adhered to the front and back surfaces and inside of the polyurethane foam into a pleated shape, an accordion pleated machine is used. Forming is performed so that the pitch p is 10 mm which defines the peak, and the folding ratio by pleating is about four times that of the flat state.
A difference as shown in the following Table 3 occurred between Example 2 which was formed into a pleated shape in this way and that which was not formed into a pleated shape (Comparative Example 4). Example 2
In Comparative Example 4, the adhering amount of the adsorbent particles was 1140 g / m ² .
Was 290 g / m ² .

[0020]

[Table 3]

Due to the pleated shape effect, a significantly lower pressure loss was achieved as compared with the flat shape, and a significant improvement in deodorizing performance was observed. To measure the pressure loss, set the test filter in the wind tunnel, give the wind speed from the fan, and wind speed 3m / sec.
The pressure difference between the upstream and downstream of the filter was measured with a pressure loss meter. Measurement of deodorizing performance is as follows: inner diameter 14 mm, length 20
After setting a sample cut to a diameter of 14 mm in the center of a 0 mm glass tube, a single gas as shown in the following Table 4 was ventilated at a flow rate of 12 liter / min and a wind speed of 1.3 m / sec. The gas concentrations before and after the sample introduction were measured by a gas chromatograph having a flame ionization detector, and the removal rate was calculated from the difference between the concentrations.

[0022]

[Table 4]

The base material 2 is based on a polyurethane foam having a three-dimensional network skeleton structure.
By having high aeration performance and adsorbent particles adhered in a dry state, the coverage of the binder component on the surface of the adsorbent particles is reduced, the decrease in deodorizing performance is small, and the adsorbent particles per unit area are reduced. The amount of adhesion can be increased.

For the optimum pleat shape, the pitch interval suitable for the base material 2 serving as the base may be appropriately designed in consideration of the allowable thickness of the target product and the pressure loss.
When the pitch interval is narrow, the folding ratio increases, so that the deodorizing performance increases.However, there is a problem that the pressure loss increases, and when the pitch interval is too wide, the pressure loss increases and the deodorizing performance decreases. Occurs. The pitch interval at which the pressure loss can be reduced most depends on the peak height of the pleats, the thickness of the base material 2 serving as the base, the number of cells, and the particle size of the adsorbent particles to be adhered. The thickness of the substrate 2 is preferably 1 to 10 mm, preferably about 2 to 5 mm, and the number of cells is 6 to 80 _PPI , preferably 9 to 50 _PPI .
_PPI .

As described above, according to the present invention,
High dust collection performance and high deodorization performance can be obtained even under use conditions at a high wind speed.

A preferred embodiment of the third invention shown in FIG.
A non-solvent-based binder layer applied to the surface and inside of a porous skeleton structure of a polyurethane foam having a fine three-dimensional network skeleton structure of cells on one or both sides, and a part of the non-solvent-based binder layer is contacted and fixed. The base material 3 is composed of the adsorbent particles whose remaining portions are exposed. A dust collecting filter layer 4 is formed on the surface layer of the base material 3, and the whole is formed into a pleated shape. The base material 3 functions as a deodorizing filter.

The adsorbent particles were the same as those used for the substrate 2 described above. The air permeability of the polyurethane foam serving as the base of the base material 3 is, as in the case of the base material 2 described above, the amount of air passing through a Frazier-type testing machine based on JIS L 1004-11972 (test method for cotton fabric) (cm).
⁽³ / cm ² / sec) is 150 or more, preferably 250 or more when measured with a thickness of 10 mm. The number of cells is 6 to 80 _PPI , preferably 9 to 50 _PPI .
_PPI .

A dust collecting filter layer 4 is provided on the surface layer of the base material 3 as in the base materials 1 to 4 shown in Table 2 above, and the dust collecting filter layer 4 is a polyurethane foam used as a base of the base material 3. , Non-woven fabric, paper, etc. can be suitably used,
This layer 4 may have a dust collecting performance.

In order to form a laminate of the base material 3 and the dust collecting filter layer 4 into a pleated shape, an accordion pleated machine is used, the peak height h is 20 mm, and the pitch p between the peaks is 10 mm. Processed to. The thickness t of the base material 3 was 2.5 mm, and the thickness of each of the dust collecting filter layers 4 was 1 mm, and the overall thickness was 4.5 mm.

Example 3 The above-mentioned substrate 3 was used for the deodorizing filter layer of this example, and the dust collecting filter layer 4 was made of polyurethane having a three-dimensional reticulated skeleton structure having a cell number of 40 _PPI and a thickness of 1 mm. After laminating the base material 3 using a foam to reduce the overall thickness to 4.5 mm, using an accordion pleating machine, the folding magnification is 4 times, and the peak height h is 20 mm.
mm and a pitch p of 10 mm. The lamination method is as follows. An acrylic emulsion binder manufactured by Soken Chemical Co., Ltd. is coated and dried on one surface of the base material 3 beforehand so as not to impair air permeability so as to be 40 g / m ^2, and then the surface of the base material 3 is coated. 1mm thick on the back
Dust collecting filter layer 4 by bonding polyurethane foam
Was formed. In addition to the lamination method of Example 3, a hot-melt web, film or powder is applied to the substrate 3 and the dust-collecting filter layer 4 is heated on the substrate 3 when forming into a pleated shape. It can also be fused.

Example 4 A dust-collecting filter (Mitsui Petrochemical (Mitsui Petrochemical Co., Ltd.) using the same base material 3 as in Example 3, with a polypropylene resin net core wrapped with a polypropylene nonwoven fabric on one side of the windward base material 3 EB-04HZ5, product weight 20g /
m ² ), and the same dust collecting filter as in Example 3 was used on the leeward side. Pleated forming was performed in the same manner as in Example 3.

Comparative Example 5 Thickness: 20 mm, pleat folding ratio: 12.5 times, peak height: 2
A paper based on 0 mm and 3.2 mm pitch paper with a deodorant attached at 115 g / m ² was prepared.

The results of comparison between Examples 3 and 4 and Comparative Example 5 are as shown in Table 5 below. Note that “L” in Table 5
V. "" Means "linear velocity".

[0034]

[Table 5]

As is clear from the results shown in Table 5 above, those of Examples 3 and 4 have higher deodorizing performance and dust collecting performance while having a lower pressure loss than those of Comparative Example 5. It can be realized. It is considered that the reason for this is that the base material 3 which is a deodorizing filter based on a polyurethane foam having a three-dimensional network skeleton structure has good air permeability and high deodorizing performance.

In the above-described embodiment, the entire structure has a three-layer structure. However, a two-layer structure in which the dust collecting filter layer 4 is laminated on only one side of the base material 3 may be used, or a polyurethane having an antibacterial effect may be added. It may have a multi-layer structure in which a foam, nonwoven fabric, paper, or the like is laminated on one or both sides of the base material 3. In addition, if the base material 2 as the deodorizing filter in FIG. 4, the deodorizing filter layer in FIG. 6, and the base material 3 were based on a polyurethane foam having a three-dimensional networked skeleton structure, a deodorant and a binder were simply kneaded. It may be a deodorizing filter in which the foam body is immersed and impregnated with the slurry and dried.

The optimum peak height and pitch interval when forming into a pleated shape are determined by the thickness and the number of cells of the dust collecting filter layer 4 and the base material 3, and in the case of non-woven fabric and paper, the basis weight or the amount of adhesion to the base material 3. Because it changes depending on the size of the adsorbent particles,
It can be appropriately designed in consideration of the thickness of the target product, the allowable pressure loss, and the like. In order to perform the pleating process, it is necessary to appropriately determine the processing temperature according to the forming speed and the type of the base material 3. However, in the pleating process of the first and second embodiments, the upper plate and the lower plate are heated. Set the plate temperature to 1 for both
The molding was performed at a temperature of 75 ° C. and a speed of 30 peaks / min. Further, in the pleating process of Example 3, the temperature of the heater on the upper plate side in contact with the polypropylene-based nonwoven fabric layer was set to 60 ° C.
C., the temperature of the lower heater in contact with the polyurethane foam layer was set at 175.degree. C., and molding was performed at a speed of 30 peaks / min.

The presence of the dust collecting filter layer 4 is useful not only for adding secondary dust collecting performance but also for preventing the adsorbent particles from dropping from the substrate 3.

[0039]

As described above, according to the present invention, since the pressure loss of the base material itself is reduced, high dust collecting performance and high deodorizing performance can be obtained. Is effective in adding dust collection performance and preventing the adsorbent particles from falling off.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the first invention.

FIG. 2 is a diagram showing a method for measuring pressure loss.

FIG. 3 is a diagram showing a method of measuring air permeability.

FIG. 4 is a side view showing an embodiment of the second invention.

FIG. 5 is a diagram showing a method for measuring an adsorption capacity.

FIG. 6 is a side view showing an embodiment of the third invention.

[Explanation of symbols]

 1,2,3 substrate

Claims (4)

[Claims] 1. An air purifying filter comprising a pleated polyurethane foam having a three-dimensional network skeleton structure with fine cells on one or both sides. 2. The cell number of the polyurethane foam is 6 to 8
The air purification filter according to claim 1, wherein the air purification filter is set to 0 _PPI . 3. A non-solvent binder layer applied to the surface and inside of a porous skeleton structure of a polyurethane foam having a fine three-dimensional network skeleton structure on one or both sides of a cell; Adsorbent particles that are fixed in contact and the remaining part is exposed, and the adsorbent particles are at least 1/50 of the average inter-skeleton distance of the polyurethane foam,
An air purifying filter, wherein a substrate having an average particle size of 1.5 times or less is formed into a pleated shape. 4. A non-solvent binder layer applied on the surface and inside of a porous skeleton structure of a polyurethane foam having a fine three-dimensional network skeleton structure with cells on one or both sides, and a part of the non-solvent binder layer An air purifying filter comprising a base material comprising adsorbent particles which are fixed in contact and the remaining part is exposed, a dust collecting filter layer is formed on a surface layer of the base material, and the whole is formed into a pleated shape. .