JP2014064995A - Filter element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter element in which a pleat is formed in a sheet-shaped filter medium, and a projection part is provided on each wall surface facing mutually between a ridge line and a trough line of the pleat, which is a filter element having a small dimensional error because the sheet-shaped filter medium does not slide when providing the projection part by an embossing roll or the like.SOLUTION: A filter element is described as follows. A pleat is formed in a sheet-shaped filter medium containing thermoplastic fibers, and a first projection part and a second projection part are provided on each wall surface facing mutually between a ridge line and a trough line of the pleat. The second projection part is formed between the first projection part and the ridge line of the pleat, separately from the first projection part on every wall surface, and the height of the second projection part is lower than the height of the first projection part.

Description

  The present invention relates to a filter element formed with pleats that is used by being mounted on an air conditioner in a building air conditioner, a factory air conditioner, a hospital air conditioner or the like.

  For air conditioning equipment in building air conditioning, factory air conditioning, hospital air conditioning, and the like, a filter element in which a sheet-like filter medium is bent to increase its surface area is used to remove dust.

  As such a filter element, it is necessary to keep the interval between the sheet-like filter media constant. For this reason, protrusions by embossing or the like are provided on both wall surfaces of the sheet-like filter medium, and the protrusions on both wall surfaces abut against each other. What was made known is known. For example, in Patent Document 1, as shown in FIG. 8, a saddle material web is bent in a zigzag shape along a fold line in the width direction, and a V-shaped corner bottom crease is formed on an adjacent fold wall facing the V shape. An air filter medium is described in which a projecting portion formed of a gentle slope from a line and a steep slope at an angle θ from a position a from both tip edges is formed and the gentle slopes are in contact with each other.

  In Patent Document 1, FIG. 9 is shown as a plan view of a brazing material web after embossing. As is clear from this figure, the height of the convex portion or the depth of the concave portion is close to 0 in the vicinity of the fold extending in the width direction, that is, the embossing roll portion corresponding to the vicinity of the fold has unevenness. There are almost no embossing rolls, and both of the embossing rolls are nearly flat. Since the shape close to the flat spreads in a band shape in the width direction of the embossing roll, when embossing is performed, the portion of the shape close to the flat corresponding to the vicinity of the crease is bent between the pair of embossing rolls. There has been a problem that the material web is slippery, and there has been a problem that the position of the folds of the embossed saddle material web is shifted, and as a result, the intervals between the creases become uneven.

JP-A-9-220427

  The present invention solves the above-mentioned problems, and is provided with an embossing roll in a filter element in which pleats are formed on a sheet-like filter medium, and projecting portions are provided on respective wall surfaces facing each other between a ridge line and a valley line of the pleat. It is an object of the present invention to provide a filter element in which a sheet-like filter medium is not slipped when a protrusion is provided by a method, and as a result, has a small dimensional error.

  In order to solve the above-mentioned problem, in the invention according to claim 1, pleats are formed on a sheet-like filter medium containing thermoplastic fibers, and each of the wall surfaces facing each other between the ridge line and the valley line of the pleat is first. And the second protrusion, and the second protrusion is separated from the first protrusion between the first protrusion and the ridge line of the pleats on any wall surface. The filter element is characterized in that the height of the second protrusion is lower than the height of the first protrusion.

  According to the present invention, in the filter element in which the pleat is formed on the sheet-shaped filter medium, and the protruding portion is provided on each wall surface facing each other between the ridge line and the valley line of the pleat, when the protruding part is provided by an embossing roll or the like Therefore, it is possible to provide a filter element with little dimensional error.

It is a figure which shows an example of the filter element of this invention, and its manufacture process. It is the elements on larger scale of an example of the filter element of the present invention. It is a figure which shows another example of the filter element of this invention, and its manufacture process. It is the elements on larger scale of another example of the filter element of this invention. It is a figure which shows an example of the protrusion part of the filter element of this invention. (A) is a plan view, and (b) is an elevation view thereof. It is a figure which shows another example of the protrusion part of the filter element of this invention. (A) is a plan view, and (b) is an elevation view thereof. It is a perspective view of the filter unit which consists of a filter element of the present invention. It is sectional drawing of the conventional filter element. It is a top view after embossing of the conventional filter element.

  Hereinafter, embodiments of the filter element according to the present invention will be described in detail.

In the filter element 10 of the present invention, as illustrated in FIGS. 1 to 3, pleats are formed on a sheet-like filter medium 11 containing thermoplastic fibers, and the pleats between a ridge line 12 and a valley line 13 are mutually connected. The first protrusions A ₁ (21) and B ₁ (31) and the second protrusions A ₂ (22) and B ₂ (32) are provided on the respective wall surfaces 20 and 30 facing each other. 20 and 30, the second protrusions A ₂ (22) and B ₂ (32) are located between the first protrusions A ₁ (21) and B ₁ (31) and the mountain line 12 of the pleats. The first protrusions A ₁ (21) and B ₁ (31) are spaced apart from each other, and the heights of the second protrusions A ₂ (22) and B ₂ (32) are the first protrusions. A filter element characterized by being lower than the height of the parts A ₁ (21) and B ₁ (31) is there.

In the explanatory view of FIG. 1, the sheet-like filter medium 11 is bent along the pleat mountain line 12 and the valley line 13 from the left hand to the right hand, and the first protrusions A ₁ and B ₁ come into contact with each other to filter. A state in which the element 10 is formed is shown. Further, in the explanatory view of FIG. 3, the sheet-shaped filter medium 11 is bent along the pleat mountain line 12 and the valley line 13 from the left hand to the right hand, and the first protrusions A ₁ and B ₁ are the wall surfaces 30 and 20. It is shown that the filter element 10 is formed in contact with the. The configuration shown in FIG. 3 is suitable when the pleat interval is required to be relatively narrow. In the present invention, the distance between the pleat mountain line 12 and the valley line 13 is preferably 50 to 500 mm, more preferably 70 to 280 mm, and still more preferably 90 to 180 mm. If it is less than 50 mm, the necessity of providing a separator may be reduced, and the processing cost for providing a protrusion as a separator may be expensive. Moreover, when it exceeds 500 mm, it may become impossible to maintain the distance between the peaks with high accuracy.

The first protrusions A ₁ and B ₁ and the second protrusions A ₂ and B ₂ can be formed by embossing a sheet-shaped filter medium containing thermoplastic fibers. In addition, it is possible to make a crease easily by making a streak in the pleat peaks and valleys during the embossing. This embossing can employ a method in which a sheet-like filter medium is passed between a pair of heated forming rolls that have irregularities and the irregularities mesh with each other, and pressurizes. Alternatively, it is possible to employ a method in which a heated sheet-shaped filter medium is passed between a pair of coolable forming rolls and pressurized while cooling. In the case of embossing, the maximum height of the first protrusions A ₁ and B ₁ is preferably 1 to 9 mm, and more preferably 2 to 8 mm. This height is also related to the cross-sectional shape of the first protrusion. When the cross section is trapezoidal, the height is preferably 1 to 7 mm, and when the cross section is triangular or semicircular, it is 2 to 9 mm. Preferably there is. When the cross section is triangular or semicircular, the filter medium can be sufficiently stretched by embossing compared to the trapezoidal shape, so that the height can be made higher than that of the trapezoidal shape.

FIG. 2 is a partially enlarged view of the filter element 10 of FIG. FIG. 5 shows a state before the filter element of FIG. 1 is bent. In the example of FIGS. 2 and 5, the first protrusion A ₁ (21) whose bottom surface is composed of the long side 211 and the short sides 212 and 213 on the wall surface 20 is the longitudinal direction of the sheet-like filter medium (or the pleat forming direction). ) So as to have a long side 211 parallel to (). Further, the protrusion A ₁ (21) has a rounded triangular mountain line side slope 214 with a short side 212 on the side close to the mountain line 12 and a first vertex 215 as a tip, and a valley line 13. And a rounded trapezoidal valley-side slope 216 having a short side 213 as a base and a second vertex 217 as a tip on the near side, and the height of the first vertex 215 is the second vertex 217. The line 218 connecting the first vertex 215 and the second vertex 217 is a ridge line, which is the tip of the protruding portion A ₁ (21).

Further, in the example of FIG. 2 and FIG. 5, the first protrusion _A 1 (21) the first protrusion _{A 1} first protrusion _A 1 next (21) of the same shape '(21') Is arranged so as to protrude from the back side of the sheet-like filter medium. Then, the first protrusion A ₁ and '(21') and the first protrusion A _{1 (21),} at a position of point symmetry, and has a further front and back tipping positional relationship. The wall surface 30 has a first protrusion B ₁ (31 having a position and a shape symmetrical to the first protrusions A ₁ (21) and A ₁ ′ (21 ′) with the valley line 13 as the axis of symmetry. ), B ₁ ′ (31 ′). Specifically, the protruding portion B ₁ (31) is short on the side near the mountain line 12 and on the side near the valley line 13 with the mountain side slope 314 having the short side 312 as the base and the first vertex 315 as the tip. A valley-side slope 316 having a side 313 as a base and a second vertex 317 as a tip, and the height of the first vertex 315 is higher than the height of the second vertex 317. A line 318 connecting the first vertex 315 and the second vertex 317 is a ridge line, which is the tip of the _first protrusion B ₁ (31). Therefore, when the pleats are formed, the distal end 218 of the first protrusion A ₁ (21) and the distal end 318 of the first protrusion B ₁ (31) are in contact with each other. Further, the tip 218 ′ of the first protrusion A ₁ ′ (21 ′) and the tip 318 ′ of the first protrusion B ₁ ′ (31 ′) are in contact with each other.

The shape of the first protrusion A ₁ (21) or B ₁ (31) is such that the sheet-like filter medium 11 is bent along the pleat mountain line 12 and the valley line 13, and the first protrusion A ₁ , B _{1 is formed.} As long as the filter elements 10 can be formed by contacting each other, or as long as the filter elements 10 are formed by contacting the first protrusions A ₁ and B ₁ with the wall surfaces 30 and 20, it is particularly limited. In addition to FIGS. 2 and 5, for example, the shapes of FIGS. 4 and 6 are possible. FIG. 6 shows a state before the filter element of FIG. 4 is bent.

4 and in the example of FIG. 6, the first protrusion _A 1 is (21), the longitudinal direction (or the forming direction of the pleats of the sheet-like filter medium bottom surface wall 20 is made of a long side 211 and short sides 212 and 213 Metropolitan ) So as to have a long side 211 parallel to (). In addition, the protrusion A ₁ (21) has a semi-elliptical mountain line-side slope 214 having a short side 212 as a base and a first vertex 215 as a tip on the side close to the mountain line 12 and a side near the valley line 13. Have a semi-elliptical valley-side slope 216 having a short side 213 as a base and a second vertex 217 as a tip, and the height of the first vertex 215 and the height of the second vertex 217 are equal. A line 218 connecting the first vertex 215 and the second vertex 217 is a ridge line, which is the tip of the protruding portion A ₁ (21). Therefore, the tip 218 is parallel to the wall surface 20.

Further, in the example of FIG. 4 and FIG. 6, the first protrusion _A 1 (21) the first protrusion _{A 1} first protrusion _A 1 next (21) of the same shape '(21') Is arranged so as to protrude from the back side of the sheet-like filter medium. Then, the first protrusion A ₁ and '(21') and the first protrusion A _{1 (21),} at a position of point symmetry, and has a further front and back tipping positional relationship. The wall surface 30 has a first protrusion B ₁ (31 having a position and a shape symmetrical to the first protrusions A ₁ (21) and A ₁ ′ (21 ′) with the valley line 13 as the axis of symmetry. ), B ₁ ′ (31 ′). Specifically, the protrusion B ₁ (31) is formed on the side close to the mountain line 12 with a semi-elliptical mountain line side slope 314 having a short side 312 as a base and a first vertex 315 as a tip, and a valley line 13. It has a semi-elliptical valley-side slope 316 having a short side 313 as a base and a second vertex 317 as a tip on the near side, and the height of the first vertex 315 and the height of the second vertex 317. Are equal, and a line 318 connecting the first vertex 315 and the second vertex 317 is a ridgeline, which is the tip of the _first protrusion B ₁ (31). Thus, the tip 318 is in parallel with the wall 20, when the pleats are formed, the distal end of the distal end portion 218 and the first projecting portion _B 1 of the first protrusion _A 1 (21) (31) The part 318 is in contact with the part 318. Further, the tip 218 ′ of the first protrusion A ₁ ′ (21 ′) and the tip 318 ′ of the first protrusion B ₁ ′ (31 ′) are in contact with each other.

The length of the long side 211 of the bottom surface of the first protrusion A ₁ (21) depends on the distance D _PV between the pleat mountain line 12 and the valley line 13 but is 10 to 90 mm less than the distance D _PV. It is preferable that the size is less by 20 to 50 mm. If it is less than 10 mm, pleat formation may be difficult, and if it exceeds 90 mm, the effect of the separator may be reduced. Moreover, it is preferable that both short sides 212 and 213 of a bottom face are 3-20 mm, It is more preferable that it is 5-15 mm, It is still more preferable that it is 7-13 mm. If it is less than 3 mm, the height of the protruding portion may not be sufficiently secured, and if it exceeds 20 mm, the gas passage resistance may be too large.

In the present invention, in addition to the first protrusion described above, the second protrusions A ₂ (22) and B ₂ (32) are provided on any of the wall surfaces 20 and 30. In the example of FIGS. 2 and 5, the second protrusion A ₂ (22) whose bottom surface is composed of the long side 221 and the short sides 222 and 223 on the wall surface 20 is the longitudinal direction of the sheet-like filter medium (or the pleat forming direction). ) Are arranged so as to have long sides 221 parallel to each other. Further, the protrusion A ₂ (22) has a mountain-side slope with a short side 222 on the side close to the mountain line 12 and a valley-side slope with a short side 223 on the side close to the valley line 13. The tip of the protrusion A ₂ (22) has a quadrangular shape parallel to the wall surface 20. Alternatively, it is a convex curved surface formed by rounding this quadrangle. Here, the long side means the side in the longitudinal direction of the sheet-like filter medium, the short side means the side in the direction intersecting the long side, and the length of the long side is the short side. It is not necessarily longer than the length, and may be shorter.

Specifically, a second protrusion A ₂ ′ (22 ′) having the same shape as the second protrusion A ₂ (22) is adjacent to the second protrusion A ₂ (22) on the back side of the sheet-like filter medium. It is arranged to protrude. Then, the second projecting portion A ₂ and '(22') and the second protrusion A _{2 (22),} at a position of point symmetry, and has a further front and back tipping positional relationship. Further, the wall surface 30 has a valley line 13 as an axis of symmetry, and a second protrusion B ₂ (32) having a position and shape that is axisymmetric to the second protrusions A ₂ (22) and A ₂ ′ (22 ′). ), B ₂ ′ (32 ′). Specifically, the second protrusion B ₂ (32) having the bottom surface of the wall surface 30 consisting of the long side 321 and the short sides 322 and 323 is parallel to the longitudinal direction (or the pleat forming direction) of the sheet-like filter medium. The long side 321 is arranged. The protrusion B ₂ (32) has a mountain-side slope with a short side 322 as a base on the side close to the mountain line 12, and a valley-side slope with a short side 323 as a base on the side close to the valley line 13. The tip of the protrusion B ₂ (32) has a quadrangular shape parallel to the wall surface 20. Alternatively, it is a convex curved surface formed by rounding this quadrangle.

The height of the second protrusions A ₂ (22) and B ₂ (32) needs to be lower than the height of the first protrusions A ₁ (21) and B ₁ (31). Here, the height of the protruding portion means the height of a point at the highest height of the protruding portion. When the height is higher than the first protrusions A ₁ (21) and B ₁ (31), there is a problem that the ventilation resistance of the filter element increases. In addition, molding by embossing or the like may be difficult. Further, when the first protrusions A ₁ (21) and B ₁ (31) on the opposite wall surfaces are not in contact with each other, or in the example of FIG. 3, the first protrusions A ₁ (21), B ₁ (31) May not contact the wall surfaces 30 and 20 in some cases. The height of the second protrusions A ₂ (22) and B ₂ (32) is not particularly limited as long as it is lower than the height of the first protrusions A ₁ (21) and B ₁ (31). However, when embossing is performed, the maximum height is preferably 1 to 7 mm, and more preferably 2 to 6 mm. This height is also related to the cross-sectional shape of the protrusion. When the cross section is trapezoidal, the height is preferably 1 to 5 mm, and when the cross section is triangular or semicircular, it is 2 to 7 mm. preferable.

In addition, the length of the long side 221 of the bottom surface of the second protrusion A ₂ (22) is determined by the distance D _PV between the pleat mountain line 12 and the valley line 13 and the bottom surface of the _first protrusion A ₁ (21). Although it depends on the length of the long side 211, it is preferably 3 to 30 mm, more preferably 5 to 15 mm, and still more preferably 8 to 12 mm. If it is less than 3 mm, slippage of the sheet-like filter medium may occur during embossing, and if it exceeds 30 mm, the length of the long side 211 of the bottom surface of the first protrusion A ₁ (21) cannot be sufficiently secured, The function as a separator may be insufficient.

Further, the second protrusion _A 2, _{B 2} includes a first protrusion _A 1 _(21), the first protrusion _A 1 between B 1 and (31) and the pleat peaks line 12, _{B 1} As long as the second protrusions A ₂ and B ₂ are formed apart from each other, the positions where the second protrusions A ₂ and B ₂ are arranged are not particularly limited. As illustrated in FIGS. It is possible to arrange the parts A ₁ and B ₁ and the second protrusions A ₂ and B _{2 so as} to be adjacent to each other. Specifically, the short sides 212 and 312 of the bottom surfaces of the first protrusions A ₁ and B ₁ and the short sides 223 and 323 of the second protrusions A ₂ and B ₂ can be arranged adjacent to each other. It is. In this case, it is not necessary to arrange all the first protrusions A ₁ and B ₁ so as to be adjacent to each other, and as illustrated in FIG. 1, the first protrusions A ₁ and B ₁ that are continuously arranged are used. Among them, it is possible to arrange them for each of several first protrusions A ₁ and B ₁ . Also, not necessarily first protrusion _A 1, _{B 1} is not necessary to arrange so that adjacent to the first protrusion _A 1 _(21), B 1 first adjacent (31) of the protrusion _{A 1} '(21'), B ₁ '(31') and the protruding portion A ₃ '(22') having the same form as the _second protruding portions A ₂ and B ₂ disposed between the pleat mountain line 12 ), B ₃ ′ (33 ′) can be arranged as the second protrusion. Further, as illustrated in FIGS. 2 and 5, in addition to the second protrusion _A 2, _{B 2,} the second protrusion _A 2, _{B 2} same form as the projecting portion _{A 3} of the '(22' ), B ₃ ′ (33 ′) can be arranged as another second protrusion.

As described above, in FIG. 2 and FIG. 5, in addition to the second protrusions A ₂ (22) and B ₂ (32), another second protrusions A ₃ ′ (22 ′) and B ₃ ′ (33 ') has been arranged, in particular, the second projecting portion a ₃ of another' ( 'a ₃ next to)' 23 (23 ') and the second protrusion a ₃ of another same shape It arrange | positions so that (23) may protrude in the back side of a sheet-like filter medium. Then, a the other second protruding portion A _{3 (23)} and another second protrusion A ₃ '(23'), at a position of point symmetry, and has a further positional relationship sides are upset. In addition, another second protrusion having a position and a shape symmetrical to another second protrusions A ₃ ′ (23 ′) and A ₃ (23), with the valley line 13 as the axis of symmetry, on the wall surface 30. B ₃ ′ (33 ′) and B ₃ (33) are arranged. Thus, in this invention, the 2nd protrusion part can have two or more types of shapes.

As illustrated in FIGS. 2 and 5, when the first protrusions A ₁ and B ₁ and the second protrusions A ₂ and B ₂ are arranged adjacent to each other, the second protrusion A The width of the bottom surfaces of ₂ and B ₂ is preferably the same as the width of the bottom surfaces of the first protrusions A ₁ and B ₁ , and there is an advantage that the embossing roll can be easily manufactured. Similarly, when the first protrusions A ₁ ′, B ₁ ′ and another second protrusions A ₃ ′, B ₃ ′ are arranged adjacent to each other, the other second protrusions A ₃ ′ are arranged. The width of the bottom surface of B ₃ is preferably the same as the width of the bottom surface of the first protrusions A ₁ ′ and B ₁ ′, and the same width has the advantage that the embossing roll can be easily manufactured. .

In the present invention, as described above, the first protrusions A ₁ (21), B ₁ (31) and the second protrusions are formed on the wall surfaces 20 and 30 facing each other between the mountain line 12 and the valley line 13 of the pleat. Projecting portions A ₂ (22) and B ₂ (32) are provided, and the second projecting portions A ₂ (22) and B ₂ (32) are the first projecting portions in any of the wall surfaces 20 and 30. Since the first protrusions A ₁ (21) and B ₁ (31) are formed apart from each other between the A ₁ (21) and B ₁ (31) and the pleat mountain line 12, the embossing It is possible to provide a filter element with little dimensional error as a result of no slippage of the sheet-like filter medium when the protrusion is provided by a roll or the like.

  In the embodiment illustrated in FIGS. 1 to 4, the preferred dimension of the filter element of the present invention is such that the height D of the filter element is preferably 50 to 500 mm, more preferably 70 to 280 mm, and 100 to More preferably, it is 180 mm. If it is less than 50 mm, the necessity of providing a separator may be reduced, and the processing cost for providing a protrusion may be expensive. Moreover, when it exceeds 500 mm, it may become impossible to maintain the distance between the peaks with high accuracy. Moreover, it is preferable that the width H of a filter element is 50-1500 mm, and it is more preferable that it is 200-700 mm. If it is less than 50 mm, there may be a case where a sufficient interval between the projecting portions as the separator cannot be secured. If it exceeds 1500 mm, the structure of the filter element may become unstable during ventilation. Further, the length W of the filter element is preferably 50 to 1500 mm, and more preferably 200 to 700 mm. If it is less than 50 mm, the intended filtration area may not be obtained, and if it exceeds 1500 mm, the structure of the filter element may become unstable during ventilation.

In the present invention, as illustrated in FIG. 7, a filter unit 50 can be manufactured by attaching a rigid frame 40 to the filter element 10, and the filter unit 50 can be arranged in a general air conditioning facility or the like. As the practical dimensions of the case of disposing the filter element of the present invention generally air conditioning, a generic dimension of the filter unit fitted with a rigid frame to the filter element, the height H _U 610 mm × width W _U It is preferable that the dimension is such that one or a plurality of filter elements can be accommodated in 610 mm × depth D _U 150 mm.

  Next, a preferable embodiment of the sheet-shaped filter medium 11 that can be applied as the filter element of the present invention will be described. The sheet-like filter medium is not particularly limited as long as it is a gas-permeable material including thermoplastic fibers. For example, a fiber substrate such as a woven fabric, a knitted fabric, a net, or a non-woven fabric can be applied. Among these, a non-woven fabric is particularly preferable because it can efficiently use the total area of the fiber surface widely and has many small voids formed by the fibers. In addition, since the sheet-like filter medium contains thermoplastic fibers, it has a characteristic that it temporarily stretches when heated and has rigidity after processing, and it is easy to form protrusions by embossing or the like. Furthermore, there is an advantage that the height of the protruding portion can be increased as compared with inorganic fibers or the like. In addition to the thermoplastic fiber, it is possible to include a resin having thermoplasticity.

  The nonwoven fabric (hereinafter referred to as the nonwoven fabric substrate) as the fiber substrate is not particularly limited, and the structure of the nonwoven fabric substrate is typically a fiber length of 15 to 100 mm and a crimp number of 5 to 30 / inch. Generally called a dry method, in which a fiber called a staple fiber is formed on a fiber web using a card machine or an air array device, and then the constituent fibers are bonded together using an adhesive fiber or an adhesive. There is a nonwoven fabric obtained by a manufacturing method. Note that a nonwoven fabric obtained by bonding constituent fibers using an adhesive fiber such as a composite fiber is a suitable material because it is a clean material that is friendly to the environment and has excellent thermoformability. In addition to the dry method, there is a nonwoven fabric obtained by a production method called a spun bond method, a melt blow method, a wet method or the like. Moreover, the nonwoven fabric which made the fiber web obtained by these manufacturing methods act on a needle | hook, a water flow, etc. and entangled a constituent fiber is also applicable. Moreover, the composite nonwoven fabric which combined the nonwoven fabric obtained by these manufacturing methods is also preferable.

  In order to obtain a filter element, it is desirable that high dust collection efficiency can be obtained while maintaining a low pressure loss. That is, it is preferable to use a nonwoven fabric that has a high dust collection efficiency and can extend the filtration life. As such a nonwoven fabric, for example, ultrafine fibers having an average fiber diameter of 0.1 to 10 μm formed by a melt blow method and heat-fusible fibers made of short fibers having an average fiber diameter of 10 to 50 μm are mixed, Moreover, a nonwoven fabric in which constituent fibers are bonded by the heat-fusible fiber can be exemplified. With such a nonwoven fabric, it is possible to have a high dust collection efficiency with ultrafine fibers and a bulky structure with heat-fusible fibers made of short fibers, and as a result, a state in which low pressure loss is maintained. It is possible to obtain high dust collection efficiency. It is also possible to obtain a filter element with a lower pressure loss by laminating a spunbond nonwoven fabric on the nonwoven fabric to increase the rigidity and reduce the curvature of the pleats. In addition, if it is the said nonwoven fabric, it is applicable to a wide range of uses, such as a use of comparatively low collection efficiency, a medium-high performance use, a semi-HEPA filter, a HEPA filter, and a ULPA filter.

  As the fibers constituting the nonwoven fabric, for example, synthetic fibers such as polyester fibers, polyamide fibers, acrylic fibers, modacrylic fibers, polypropylene fibers, polyethylene fibers, and polyurethane fibers, which are thermoplastic fibers, can be used. In addition, these fibers and synthetic fibers such as polyclar fiber, polyvinylidene chloride fiber, polyvinyl chloride fiber and polyvinyl alcohol fiber, regenerated fibers such as rayon and viscose, semi-synthetic fibers such as acetate, carbon fibers, It can be used by mixing with inorganic fibers such as glass fibers. Further, when the constituent fibers are made of organic fibers such as synthetic fibers, regenerated fibers, and semi-synthetic fibers, there is an advantage that they can be recycled or incinerated at the time of disposal after use of the filter element.

  In addition, the constituent fibers are preferably composite fibers. Examples of combinations of resin components constituting the composite fibers include polypropylene / polyethylene, polyester / low-melting polyester, polypropylene / low-melting polypropylene, nylon 66 / nylon 6, nylon 6 / Low melting point nylon, polyester / nylon 6, nylon 6 / polyethylene, polyester / polypropylene, etc.

  In addition, when the low melting point resin component of the composite fiber has thermal adhesiveness, the web constituent fiber can be thermally bonded by the resin component during embossing. Thus, when the low melting point resin component of the composite fiber has thermal adhesiveness, the fiber form can be maintained by the high melting point resin component, so that there is an advantage that the strength is excellent.

DESCRIPTION OF SYMBOLS 10 Filter element 11 Sheet-like filter medium 12 Mountain line 13 Valley line 20 Wall surface 21 1st protrusion part A ₁
21 'first protrusion A ₁ '
211 first bottom surface of the protrusion _{A 1} long sides 212 and 213 the first bottom surface of the protrusion _{A 1} short side 214 first protrusion _{A 1} mountain line side slope 215 first vertex 216 first The trough-side slope 217 of the projecting part A ₁ The second apex 218 The tip part of the _first projecting part A ₁ , the ridge line 22 The second projecting part A ₂
22 ′ second protrusion A ₂ ′
221 second protrusion _{A 2} of the bottom surface of the long sides 222 and 223 short side of the second bottom surface of the protrusion _{A 2} 23 second protrusion _{A 3} or another second protrusion _{A 3}
23 ′ second protrusion A ₃ ′ or another second protrusion A ₃ ′
31 1st protrusion B ₁
31 ′ first protrusion B ₁ ′
311 first bottom surface of the protrusion _{B 1} long sides 312 and 313 first of the bottom surface of the projecting portion _{B 1} short side 314 first protrusion _{B 1} mountain line side slope 315 first vertex 316 first The trough-side slope 317 of the protrusion B ₁ The second apex 318 The tip of the _first protrusion B ₁ , the ridge line 32 The second protrusion B ₂
32 ′ second protrusion B ₂ ′
321 second protrusion _{B 2} of the long side of the bottom surface 322, 323 a second short side of the bottom surface of the projecting portion _{B 2} 33 second protrusions _{B 3} or another second protrusion _{B 3}
33 ′ second protrusion B ₃ ′ or another second protrusion B ₃ ′
A ₁ , A ₁ ′, B ₁ , B ₁ ′ First protrusion A ₂ , A ₂ ′, B ₂ , B ₂ ′ Second protrusion A ₃ , A ₃ ′, B ₃ , B ₃ ′ 2 protrusions or another second protrusion 40 Rigid frame 50 Filter unit

Claims (1)

  Pleats are formed on a sheet-like filter medium containing thermoplastic fibers, and a first protrusion and a second protrusion are provided on each wall surface facing each other between a ridge line and a valley line of the pleat, In any wall surface, the second projecting portion is formed between the first projecting portion and the mountain line of the pleat so as to be separated from the first projecting portion, and the height of the second projecting portion. Is lower than the height of the first protrusion.

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