JP2009208014A - Molded filter medium and filter unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molded filter medium suppressing the disturbance of a pleats shape even at the time of passage of a large amount of air and suppressed in pressure loss. <P>SOLUTION: The molded filter medium is constituted of a filter medium having a pleats shape and is characterized in that a resin, of which the elongation based on JA1-1-1991 is 190% or below, is applied to the ridge-lines of the pleats of the filter medium in the direction almost vertical to the ridge-lines of the pleats in a strip-like form. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pleated filter medium used for air cleaning.

  In filters used for air cleaning, in order to reduce pressure loss during use and to obtain high collection efficiency and long life, filter media that are pleated in a mountain fold are mainly used.

  Some pleated filter media are provided with a separator in order to keep the pleat interval and prevent the area of the filter media from decreasing due to the close contact between adjacent pleats. For example, a method of inserting a comb between pleats (Patent Document 1), a method of sandwiching corrugated paper between pleats (Patent Document 2), and a direction substantially perpendicular to the pleats of pleated filter media In addition, there is a resin formed in a string shape at a predetermined interval (Patent Document 3).

Among them, a method of forming a resin in a string shape is frequently used because of its good workability. However, there has been a problem in that the shape of the pleated filter medium is deformed by the pressure of the air when high-air-volume air is passed, the pleated shape is disturbed, and the pressure loss increases.
JP 2006-1946 A JP 2000-135410 A JP-A-8-215527

  The subject of this invention is providing the shaping | molding filter medium which suppressed disorder of a pleat shape and suppressed pressure loss even at the time of high air volume air passage.

  That is, the present invention comprises a filter medium having a pleat shape, and a resin having an elongation of 0 to 190% based on JAI-7-1991 is applied in a string shape in a direction substantially perpendicular to the ridgeline of the pleat. It is the shaping | molding filter material characterized by becoming.

  Moreover, this invention is a filter unit characterized by having the shaping | molding filter medium of this invention.

  According to the present invention, it is possible to provide a shaped filter medium that suppresses pleated shape disturbance and thus suppresses pressure loss even when high air volume air passes.

  As the filter medium in the present invention, paper, synthetic fiber nonwoven fabric, glass fiber nonwoven fabric, plastic or the like can be used. Among these, a filter medium made of non-woven fabric is preferable in terms of improving dust collection performance.

  Further, these may be used in an overlapping manner. In particular, nonwoven fabrics composed of fine fibers such as melt blown nonwoven fabrics and nonwoven fabrics using split fibers as constituent fibers, and hydroentangled nonwoven fabrics, fiber-bonded nonwoven fabrics, binder-bonded nonwoven fabrics, etc. that are coarser and have shape retention. What laminated the nonwoven fabric is preferable.

Moreover, in order to improve dust collection performance, it is preferable to use the electret synthetic fiber nonwoven fabric which has an electric charge of about 10 ^{< -10} > ^-10 < ^-7 > C / cm < ² > on the filter medium surface.

  The filter medium in the present invention is pleated. By doing so, the filter medium area in a fixed opening area can be enlarged, and high collection efficiency and a long lifetime are attained. As a means for pleating the filter medium, for example, a method using a reciprocating machine or a method using a rotary pleating machine can be employed.

The pleated filter medium is fixed in a pleated shape by applying a resin.
Examples of the resin for fixing the pleat shape include a thermoplastic resin and a thermosetting resin.
In particular, a thermoplastic resin is preferable in terms of workability and cost.

  Examples of the thermoplastic resin that can be used include polyolefin, ethylene-vinyl acetate, polyurethane, and polyamide.

  You may add tackifying resin, wax, etc. to a thermoplastic resin. However, it is preferable that the resin used for the air filter does not contain a wax containing a lot of organic volatile components.

  As a softening point of a thermoplastic resin, it is preferable that it is 80 degreeC or more in the measurement based on Japanese-adhesive-materials industry standard JAI-7-1991. By setting the softening point of the thermoplastic resin to 80 ° C. or higher, the heat resistance of the molded filter medium can be maintained. The upper limit value of the softening point of the thermoplastic resin is preferably 20 ° C. or more lower than the melting point of the filter medium. When the filter medium is a nonwoven fabric, the melting point of the highest melting point among the fibers constituting the nonwoven fabric. It is preferably lower by 20 ° C. or more. Thermoplastic resin is preferably heated and melted at a temperature 20 ° C. or higher than its softening point for stable application, and then applied to the filter medium with a nozzle or the like. It is to do.

  The viscosity of the thermoplastic resin is preferably 1000 to 20000 mPa · s at the coating temperature based on the Japanese adhesive industry standard JAI-7-1991. By setting it to 20000 mPa · s or less, the resin can be appropriately infiltrated into the filter medium to be applied. Moreover, it will become difficult to flow down from the apply | coated nonwoven fabric by setting it as 1000 mPa * s or more, and it is preferable also from the point of workability | operativity. Here, the application temperature is the temperature of the thermoplastic resin when applying the thermoplastic resin to the filter medium.

  In the molded filter medium of the present invention, it is important that the elongation of the resin applied in a string shape in a direction substantially perpendicular to the ridge line of the pleats is 0 to 190% based on the Japan Adhesive Industry Standard JAI-7-1991. By setting the elongation to 190% or less, the resin applied in the shape of a string in a direction substantially perpendicular to the pleat ridgeline holds the pleat shape firmly, suppressing pleat shape disturbance even when passing high air volume air, pressure loss Can be suppressed. Further, when the filter medium is applied in a string shape in a state where the pleated filter medium is stretched and the filter medium is folded again in a state where the resin is cooled and solidified, the elongation of the resin is preferably 160% or more. . By doing so, it is possible to prevent the resin from stretching sufficiently in the part that becomes the peak of the pleats and preventing the generation of wrinkles in the filter medium, and in the part that becomes the valley, the resin sufficiently contracts and the apex of the pleats expands. Can be prevented.

  The elongation of the resin can be controlled by selecting a material, adjusting its blending ratio, selecting a melt mixing procedure, and the like. For example, the elongation can be reduced by increasing the content of the tackifying resin or using a tackifying resin having a high glass transition temperature.

  In the molded filter medium of the present invention, the resin is applied in a direction substantially perpendicular to the ridgeline of the pleats. By doing so, it is possible to maintain the pleated shape while suppressing the effective area of the filter medium from being reduced by applying the resin as much as possible.

  The string-like resin may be applied to both the air inflow side and the outflow side, or may be applied to only one of them. When applied on both sides, the strength of the shaped filter medium increases. Moreover, when apply | coating only to either one, it is preferable to apply | coat to the outflow side, in order to suppress the deformation | transformation of the filter medium by the pressure of air efficiently.

  A plurality of string-like resins are preferably provided on the filter medium in order to maintain the pleated shape, and the distance between the string-like resins can be, for example, 2.5 cm or 5 cm.

  Examples of the method for applying the resin in a string include bead processing (FIG. 1), ribbon processing (FIG. 2), dripping processing (FIG. 3), and the like. The bead processing is a method in which a pleated filter medium is once extended, a resin is applied in a string shape in a direction substantially perpendicular to a ridge line of the pleat, and the filter medium is held again in a pleated shape at a predetermined pleat interval. Ribbon processing is a method in which a resin in a semi-molten state is applied so as to bridge between the pleat vertices while maintaining the pleat interval of the pleated filter medium. The dripping process is a method in which a molten resin is applied to the slope of a pleated mountain while maintaining the pleat interval of the pleated filter medium.

  For filter media having a wide pleat interval, for example, a pleat interval (interval between peaks and peaks) of about 4 mm or more with respect to a peak height of 30 mm, bead processing and dripping processing are more preferable. This is because the length of contact with the filter medium can be increased as the resin to be applied in a string shape, so that the disorder of the pleat shape can be more effectively suppressed.

  In the bead processing, the string-like resin may be continuous or intermittent, but an intermittent shape in which a defect is provided in a portion that becomes a valley of the pleat is preferable. By doing so, it can prevent that the resin which became excess in the trough part of a pleat crushes a pleat or spreads in the string-like width direction, and reduces the filtration efficiency of a filter medium.

  In bead processing, it is preferable to keep the pleat interval at a predetermined interval before the resin is completely cured. By doing so, a predetermined pleat interval can be maintained without burdening the cured resin with extra stress. Further, as described above, even when the resin is applied in an intermittent manner in which a defect is provided in the valley portion of the pleat, adjacent intermittent pieces are fused and bonded to each other across the valley portion, and the predetermined pleat is also provided in the vicinity of the valley portion. The interval can be held efficiently and firmly.

  The molded filter medium of the present invention can be used as a filter unit by fixing the end face with a frame, for example. By using a filter unit, it can be easily replaced with an air purifier.

  As the frame body, metal, plywood, corrugated cardboard, resin and woven or knitted fabric, fiber structure such as nonwoven fabric, or the like can be used. Especially, it is preferable to use paper or a nonwoven fabric at the point which can be incinerated with a filter medium.

As a method of fixing the end face of the molded filter medium with the frame body, for example, there is a method of bonding both the molded filter medium and the frame member with an adhesive resin.
Examples of the adhesive resin include a thermosetting resin such as an epoxy resin and a urethane resin, a thermoplastic resin such as a hot melt agent, and a photocurable resin. Of these, a thermoplastic resin such as a hot melt agent is preferable in terms of excellent workability and cost.

[Measuring method]
(1) Softening point of resin It measured according to JAI-7-1991.
The measurement was performed three times using a new sample, and the average value of the measured values was taken and rounded to 0.5 ° C.

(2) Melt viscosity of resin It measured according to JAI-7-1991 A method. A single cylinder rotational viscometer was used as a measuring device. The measurement was performed twice using a new sample, the viscosity was calculated by the following formula, and rounded to two significant figures.

(3) Elongation rate of resin It measured according to JAI-7-1991. A film was prepared using a hot press in a 23 ° C. atmosphere and left for 24 hours or more. A dumbbell No. 2 shape defined in JIS K 6301 was used for punching, and a 20 mm mark was attached to the central portion. An autograph tester was used as a measuring device.

(4) Pressure loss and dust permeability of filter media Set a filter in an evaluation device according to JIS B 9908 (2001) type 3 test method, and flow air at a filter media through-flow speed of 4.5 m / min to reduce the pressure loss of the filter media ( ΔP ₁ ) was determined.
Then, to the point where it reaches the final pressure drop ΔPe plus 150Pa to [Delta] P _1, collecting supplies dust 15 or according to JIS Z8901 (1974), an evaluation unit in the dust amount trapped in the filter medium _{(W 1)} From the amount of dust (W ₂ ) collected without being collected in the downstream absolute filter, the filter medium dust transmittance P ₁ (JIS 15 class dust transmittance P1) was determined by the following formula.
P ₁ = [1- (W ₁ / (W ₁ + W ₂ ))] / 100
W ₁ = mass of JIS 15 seed particles collected by the evaluation sample W ₂ = total mass of JIS 15 seed dust particles collected by the evaluation sample and the absolute filter.

(5) Pressure loss of the filter Set the filter on the evaluation equipment according to JIS B 9908 (2001) Type 3 test method, and let air flow at a filter medium through-wind speed of 25.0 m / min, and the pressure loss (ΔP ₂ ) of the filter Asked.

(6) Ratio of structural pressure loss From the pressure loss ΔP1 of the filter medium, the pressure loss ΔP ₁ ′ of the filter medium at the filter medium through-wind speed of 25.0 m / min was calculated from the following equation.
ΔP ₁ ′ = ΔP ₁ × (25.0 / 4.5)
The structural pressure loss ratio A was calculated by the following formula.
A = (ΔP ₂ −ΔP ₁ ′) / ΔP ₂ .

[Example 1]
(Filter material)
Electret nonwoven fabric (weight per unit area 12.0 g / m ² , average fiber diameter 6.0 μm, pressure loss 1.8 Pa, thickness 0.12 mm polypropylene melt blown nonwoven fabric) and nonwoven fabric (weight per unit 73.5 g / m ²⁾ , An average fiber diameter of 24.9 μm, a pressure loss of 4.4 Pa, a dry chemical bond nonwoven fabric having a thickness of 0.50 mm, and a short fiber nonwoven fabric (average fiber diameter of 30.0 μm, basis weight of 70.0 g / m ² ) as a support. A filter medium (pressure loss: 6.3 Pa, JIS 15 type dust transmittance: 0.09%, thickness: 0.63 mm) bonded in a layer configuration of electret nonwoven fabric / dry chemical bond nonwoven fabric / short fiber nonwoven fabric was used.

(resin)
A thermoplastic resin comprising 50% by mass of an amorphous olefin copolymer, 10% by mass of crystalline polybutylene and 40% by mass of a tackifying resin, having a softening point of 141 ° C., a melt viscosity of 6500 mPa at 160 ° C., and an elongation of 170% was used.

(Pleating and resin coating)
The filter medium was cut into a width of 200 mm and pleated to a distance of 8 mm between adjacent peaks and valleys using a rotary pleating machine.
Next, with the pleated filter medium extended, three of the above resins were applied in a string shape in a direction perpendicular to the ridge line of the pleats at 160 ° C. with a nozzle (diameter 0.5 mm). The distance between the string-like resins was set to 5.1 cm.
The string-like resin was intermittently provided with a deficiency in the pleat valley, and applied to both the air inflow side and the outflow side so as to sandwich the filter medium.
Next, with the fluidity before the resin was completely cured, it was fixed to pleats having a crest distance of 3.6 mm and a crest number of 57, and allowed to stand at room temperature to cure the resin, thereby obtaining a molded filter medium. .

(Filter unit)
The end face of the molded filter medium and a frame made of a nonwoven fabric were bonded with a thermoplastic resin adhesive to obtain a filter unit.

(Evaluation)
The structural pressure loss ratio of the obtained filter was 53.0% (ΔP ₂ = 75.0a, ΔP ₁ ′ = 35.0 Pa).

[Example 2]
(Filter material)
The same one as used in Example 1 was used.

(resin)
A thermoplastic resin comprising 42% by mass of an amorphous olefin copolymer, 8% by mass of crystalline polybutylene and 50% by mass of a tackifier resin, having a softening point of 140 ° C., a melt viscosity of 3000 mPa at 160 ° C., and an elongation of 46% was used.

(Pleating and resin coating)
A molded filter medium was obtained in the same manner as in Example 1 except that the above resin was used.

(Filter unit)
Using the molded filter medium, a filter unit was obtained in the same manner as in Example 1.

(Evaluation)
The structural pressure loss ratio of the obtained filter was 52.6% (ΔP ₂ = 73.8 Pa, ΔP ₁ ′ = 35.0 Pa).

[Comparative Example 1]
(Filter material)
The same one as used in Example 1 was used.

(resin)
It consists of 60% by mass of amorphous 1-butene copolymer, 15% by mass of crystalline polybutylene and 25% by mass of tackifying resin, and uses a thermoplastic resin having a softening point of 138 ° C., a melt viscosity of 7100 mPa at 160 ° C., and an elongation of 230%. It was.

(Pleating and resin coating)
A molded filter medium was obtained in the same manner as in Example 1 except that the above resin was used.

(Filter unit)
Using the molded filter medium, a filter unit was obtained in the same manner as in Example 1.

(Evaluation)
The structural pressure loss ratio of the obtained filter was 61.0% (ΔP ₂ = 90.0 Pa, ΔP ₁ ′ = 35.0 Pa).
The filter has an increased ratio of structural pressure loss because the folded part of the pleat expands in a round shape and the flow path becomes narrower.

  The molded filter medium according to the present invention is preferably used for filters for building air conditioning, clean rooms, home air purifiers, in-vehicle use, equipment and the like.

It is the schematic which shows the bead-processed shaping | molding filter medium. It is the schematic which shows the shaping | molding filter medium by which the ribbon process was carried out. It is the schematic which shows the shaping | molding filter medium which carried out the dripping process.

Explanation of symbols

1 Filter medium 2 Resin 3 Mountain part 4 Valley part

Claims (2)

A filter medium having a pleat shape is formed, and a resin having an elongation of 0 to 190% based on JAI-7-1991 is applied in a string shape in a direction substantially perpendicular to the ridge line of the pleat. Molded filter media to do. A filter unit comprising the shaped filter medium according to claim 1.

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