JPH01224021A - Filter element - Google Patents

Abstract

PURPOSE:To enhance the collection efficiency of the title element and to reduce its gas flow resistance by providing a shaping material in parallel to the surface of a synthetic fiber melt-blown nonwoven fabric layer having a specified METSUKE (unit density), and folding the shaping material in crest-trough form to form the filter element. CONSTITUTION:The nonwoven fabric layer having at least one layer of the synthetic fiber melt-blown nonwoven fabric having 5-200g/m<2> METSUKE weight, and the shaping material substantially parallel to the surface of the nonwoven fabric is folded in crest-trough form to form the filter element. More concretely, the end of the nonwoven fabric 2 is adhered to the inner surface of a frame material 4 with a resin, and sealed to prevent leakage of air. The nonwoven fabric layer 2 is folded in crest-trough form without the intervention of a separator, and adhered to the frame material.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a filter useful in the field of filters, such as a high-performance, low-pressure-loss filter made of melt-blown nonwoven fabric, in place of conventional filter elements mainly using glass fibers. It is about elements.

(Prior Art) Japanese Unexamined Patent Publication No. 61-230711 discloses a filter element in which an electred melt-blown nonwoven fabric is folded in peaks and valleys through a pallet.

If you want to obtain a filter element with such peak-valley folding, if it has good formability, such as a HEPA filter made of glass fiber, the above-mentioned peak-valley folding can be done without any special problems, and it can be done by machine work. It can be carried out. However, in the case of melt-blown nonwoven fabrics made of organic polymers, the material is soft and has bending resilience, so the shapeability is extremely poor, and the shape is not stabilized even when folded at the peaks and valleys, and the machine work is required to fold the peaks and valleys. Not only was it difficult to perform the folding process, but also the work efficiency was quite low when the mountain-valley folding process was performed manually.

Furthermore, when a filter is produced by folding it through a separator, the filter (filtering material) is soft and bites into the separator, increasing the contact area more than expected. As a result, the airflow resistance was 3 to 10 times higher than that measured for the filter medium alone, and the low airflow resistance, which is a characteristic of an electret filter, was not fully utilized. [Problems to be solved by the invention] This book The present invention uses a melt-blown nonwoven filter medium with improved formability to form a separate-less filter, and provides a filter element having excellent collection efficiency and low airflow resistance.

[Means to solve problems]

The present invention provides a nonwoven fabric layer including at least one synthetic fiber meltblown nonwoven fabric layer having a basis weight of 5 g/m2 to 200g/+n2, and a synthetic fiber meltblown nonwoven fabric layer that exists substantially parallel to the fabric surface of the synthetic fiber meltblown nonwoven fabric layer. The gist of the present invention is a filter element comprising a shaped material having a shape of a peak-to-valley fold, and the synthetic fiber melt-blown nonwoven fabric layer being formed by folding the synthetic fiber melt-blown nonwoven fabric into a shape of a peak-to-valley fold.

To engineering ≧ Risan: Mi1. Tofu'、ro;ku1furubi■gu 、、; 、? −, I have two certificates.

At least one melt-blown nonwoven fabric layer is used which is made of various materials such as polyolefin, polyester, polyamide, polycarbonate, and aromatic materials having a basis weight in the range of 5 to 200 g/m2. If the basis weight of the melt-blown nonwoven fabric layer is less than 5 g/m'', the strength is low and the durability as a filter is insufficient, and if it is greater than 200 g/m'', the filter pressure loss will be large, which is preferable. do not have.

Furthermore, in the present invention, a spunbond nonwoven fabric layer made of a polyolefin, polyester, or polyamide polymer may be used in combination with the meltblown nonwoven fabric layer. In other words, the melt-blown nonwoven fabric layer, which is usually composed of thin fibers with an average fineness of 0.005 denier or more and 1 denier or less, is likely to become clogged due to dust adhesion, shortening the life of the filter (but , a bulky needle-punch type suf-phone on the upstream side of the air.
By adding 127 layers to the can, it is possible to eliminate the above drawbacks and extend the life of the filter.

From this point of view, it is preferable to use a spunbond nonwoven fabric used in combination with the above-mentioned material having a fineness of about 0°1 to 8 denier and a pore volume of 80% or more.

Further, since the melt-blown non-woven fabric layer usually has low breaking strength, in order to reinforce this, a thermal adhesive type spunbond non-woven fabric can be used on the most downstream side of the air flow or as an inner layer of the melt-blown non-woven fabric layer. The spunbond nonwoven fabric used for this purpose has an air permeability of 100cc/m”.
sec or more, and the breaking strength is preferably 1kg15c+++ width or more.

Furthermore, the surface charge density of each nonwoven fabric layer is 1. It is preferable that the filter medium is constructed by using at least one layer of an electroleft nonwoven fabric of OX10-I0 clone/d or higher, and by doing so, it becomes possible to manufacture a filter element with higher performance. For example, according to the findings of the present inventors, the fineness is 0
．． 005~0.5 denier, eye size 60~160g/m
HEP
It is also possible to manufacture filter elements with high performance of A class or higher. Of course, if the basis weight is reduced, it is possible to manufacture a filter with medium performance, so conditions other than the above may be selected as appropriate depending on the application.

In particular, when using an electroleft nonwoven fabric, the most suitable fiber material is a polypropylene type or polycarbonate type, which has high stability under -g usage conditions. In addition, for applications requiring heat resistance, polyphenylene sulfide, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyfluoroethylene (F
EP) or the like is preferably used as the electret material.

Next, when a plurality of nonwoven fabrics are used in the nonwoven fabric layer, it is preferable that the nonwoven fabrics have a bonding portion between them, and the integrity of the entire nonwoven fabric layer is maintained by the bonding. However, in cases where bulky spunbond nonwoven fabrics are laminated on the upstream side, the spunbond nonwoven fabrics may be joined only within the spunbond nonwoven fabric layers. For example, 10
If you try to join together a spunbond nonwoven fabric with a weight of 0 to 200g/m'' and a thickness of 1 to 2mm and a meltblown nonwoven fabric of 60 to 160g/m'', the thickness will be 2 to 3mm, and in that case, the overall bonding will be difficult. In that case, it is sufficient to bond only the spunbond nonwoven fabric layer.

The bonding may be performed by ultrasonic fusion bonding or hot embossing. However, when joining electret nonwoven fabrics, joining using ultrasonic waves is preferable because it does not reduce the electret properties.

The bonding area only needs to maintain the integrity of the nonwoven fabric layer, but it is desirable to make the bonding area as small as possible, and it is generally 10% or less, preferably 5% or less.

Furthermore, the joining performed to integrate the nonwoven fabric layers is influenced by the shape of the excipient. For example, when using a linear or plate-like excipient inserted into a nonwoven fabric, both sides of the excipient are joined in a striped manner, and the excipient and nonwoven fabric are bonded together at the same time. Preferably, integration is performed. In addition, when the excipient is a plastic material alone or a composite material with metal and is linear, plate-like, net-like, etc., is used for the surface layer or inner layer of the nonwoven fabric, a part or all of the excipient and a composite material of the nonwoven fabric may be used. A preferred method is to join a portion of the nonwoven fabric to integrate the nonwoven fabric and the excipient because it facilitates peak-valley folding.

The material of the excipient must be rust-proofed or essentially non-corrosive, such as stainless steel, aluminum, or coated iron, or a flexible material coated with plastic, etc. is suitable. A particularly suitable material is aluminum, which is preferred because it is flexible and soft. If the material of this excipient rusts, it is undesirable because it reduces the commercial value of the filter and reduces the filter performance.If the excipient is not easy to bend, it will actually impede the formability of the filter, so it should not be It is important to choose suitable materials.

In addition, the position, amount, and method of integrating the excipient into the nonwoven fabric should be determined depending on the basis weight of the nonwoven fabric. For example, in a filter element composed of layers of nonwoven fabric In this case, it is preferable to fusion-bond the excipient to the surface layer, and in the case of laminating nonwoven fabrics of 2N or more, from the viewpoint of imparting shapeability to the filter, it is preferable to fusion-bond the excipient to the surface layer or inner layer. Fusion or insertion is preferred. When the fabric weight of the nonwoven fabric increases, if it is fused to the surface layer, troubles due to the difference in fabric weight between the inner and outer layers are likely to occur during peak-to-valley folding (this is why it is preferable to insert the nonwoven fabric into the inner layer).

FIG. 1 is a partially cutaway perspective view schematically showing an example of a filter element of the present invention.

In the figure, 1 is a filter element, 2 is a nonwoven fabric layer using a synthetic fiber melt-blown nonwoven fabric having excipients, and 3
4 is a shaped object (metal wire in this case), and 4 is a frame material.

As shown in the figure, the ends of the nonwoven fabric layer 2 are bonded to the inner surface of the frame material 4 with resin and sealed to prevent air leakage. The nonwoven fabric layer 2 is folded into peaks and valleys without using a separator, and is bonded to the frame material. Of course, you can also fold the peaks and valleys through the separator. However, in this case, a pore area is generated at the portion where the separator and the nonwoven fabric layer 2 are in contact with each other, increasing ventilation resistance, so this is not very preferable, but it can be said to be effective from the viewpoint of stabilizing the form.

FIG. 2 is an enlarged sectional view of the nonwoven fabric layer 2 of FIG. 1. In the figure, 5 is a bulky nonwoven fabric, 6 is a melt-blown nonwoven fabric, and 7 is a bulky nonwoven fabric.
8 indicates a thin and strong thermal adhesive type spunbond nonwoven fabric, 8 indicates a joint, and 9 indicates a metal wire.

The nonwoven fabric layer 2 includes the bulky nonwoven fabric 5, the melt-blown nonwoven fabric 6, and a thermal adhesive type spunbond nonwoven fabric 8.
It is not in any way limited to the use of different types. Of course, there are cases in which it is composed only of the melt-blown nonwoven fabric 6. Although the joint is provided with the shaped object in between, the molded object and the joint may be provided at the same location.

Moreover, FIG. 3 is a schematic front view showing another example of the filter element of the present invention, and in the figure, the nonwoven fabric layer 2 has a composite material 10 made of metal material and plastic on both sides thereof. The end face of the nonwoven fabric layer 2 folded at peaks and valleys is adhered to the inner surface of the frame member 4 with resin 13 to prevent air leakage. In the figure, 2 and 2' indicate the same nonwoven fabric layer, but the relationship between 2 and 2' is that the center of the nonwoven fabric layer visible on the front side is 2, which corresponds to the peak of the mountain-valley fold, and the center of the nonwoven fabric layer visible on the back side is 2. ° indicates the part corresponding to the valley of the mountain-valley fold.

FIG. 4 is a schematic partial sectional view of the filter element shown in FIG. 3, viewed from above. The nonwoven fabric layer 2 is folded in peaks and valleys through a composite material 10 made of a metal wire 9 and a plastic material 11 to form a filter medium. Such an element is extremely advantageous because the pitch between the peaks is constant, so the air flow is constant, and the filter element can be made without variation in collection performance.

In the present invention, the measurement of the surface charge density is performed in the fifth step.
This is done using the method shown in the figure.

That is, in FIG. 5, a grounded metal box 14 and a metal flat electrode (area: 100c+J, material: brass) 1
A sample 16 is sandwiched between 5 and 5, and the charge generated by electrostatic induction is passed through a capacitor 17 to an electrometer 18.
The voltage is measured by , and the surface charge density is determined from the measured potential using the following calculation formula.

Q=CXV/S Q: Surface charge density (clone/ad) C: Capacitance ■: Voltage S: Area of sample (cj) Note that the nonwoven fabric layer and the excipient are substantially integrated. There is a state in which the excipient and at least a part of the nonwoven fabric layer are bonded, or a condition in which the excipient is inserted into the nonwoven fabric layer. teeth,
There is no problem if the nonwoven fabric and the excipient move in a substantially integrated manner during peak-to-valley folding, and there is a degree of freedom to the extent that no trouble occurs during the peak-to-valley folding process.

In addition, the shape of the excipient to be selected depends on the basis weight of the nonwoven fabric layer and is not determined in part, but if the basis weight is 50 g/m" or less, a mesh body is suitable;
When the fabric weight is about 100 g/m'', even linear objects can be used.This is because the melt-blown nonwoven fabric has extremely high flexibility and poor shape retention.If the fabric weight of the melt-blown nonwoven fabric is small, It is necessary to support the entire surface of the nonwoven fabric.

〔Example〕

The present invention will be explained in more detail with reference to examples.

Example 1 Polypropylene melt-blown electreft nonwoven fabric (average fiber diameter 1.6 μm, basis weight 20 g/m”, thickness 0.1
2 mm, surface charge density 6.0 × 10-10 clones/
cfll') and 6 layers of polypropylene spunbond electret nonwoven fabric (fineness 2 denier, basis weight 20 g/m
2. Thermal adhesive type) - 7 layers are stacked, and a metal wire (stainless steel 150 μm) is placed on top of the spunbond nonwoven fabric.
were arranged at intervals of 5 cm, and the entire nonwoven fabric was joined to form a nonwoven fabric in which the metal wire and the nonwoven fabric were substantially integrated.

This nonwoven fabric was folded into peaks and valleys to produce a filter element measuring 305 x 305 x 150 mm with a pitch between peaks and peaks of 6n.

When the filter performance of this filter element was evaluated according to the method of JIS-B-9908, it exhibited a collection efficiency of 99.999% or more for 0.3 μm particles, and a pressure loss of 8++ nAq. Shows performance superior to HEPA. It can also be seen that the airflow resistance is extremely low.

Comparative Example 1 A nonwoven fabric was produced by integrally bonding the same nonwoven fabric layers as those used in Example 1 without using metal wires.

This non-woven fabric was sized 305 x 305 x 15 with a pitch of 6 mm between aluminum separators (0.15 mm).
A 0 mm filter element was created.

When the performance of this filter element was evaluated in the same manner as in Example 1 using the method of J15-B-9908, the collection efficiency was 99.98% for 0.3 μm particles.

Further, the pressure loss was 18 mAq, indicating that the collection efficiency was low and the ventilation resistance was high.

〔Effect of the invention〕

A synthetic fiber melt-blown nonwoven fabric layer with a basis weight of 5 to 200 g/m'' has very poor formability and is soft, so it has been difficult to mechanically perform mountain-valley folding to produce a filter element.

In addition, when folding peaks and valleys through a separator, the nonwoven fabric layer comes into contact with the separator in such a way that it bites into the separator, increasing the dead area, which has the disadvantage of significantly increasing ventilation resistance. By adhering, fusing, or inserting the material, the shapeability improves, so that the mountain and valley folds can be performed by machine work. Therefore, filter manufacturing work can be carried out efficiently.

Furthermore, since the filter structure is sufficiently stable even when folded at peaks and valleys without using a separator, it is also possible to produce a separate filter. Therefore, not only the ventilation resistance is lower than that of the conventional one, but also the passing wind speed distribution becomes constant, so it is possible to obtain excellent collection efficiency.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view schematically showing an example of the filter element of the present invention, FIG. 2 is an enlarged sectional view of the nonwoven fabric 2 of FIG. 1, and FIG. 3 is another example of the filter element of the present invention. FIG. 4 is a partial sectional view schematically showing the structure of the filter element in FIG. 3 viewed from above, and FIG. 5 is a schematic diagram for explaining the method for measuring surface charge density. It is. 1... Filter element, 2... Nonwoven fabric layer, 3
... Shaped object, 4... Frame material, 5... Bulk nonwoven fabric, 6... Melt blown nonwoven fabric, 7... Spunbond nonwoven fabric, 8... Adhesive joint, 9... Excipients, 10.
...Composite material made of metal wire and plastic, 11...
Plastic, 12...Filter element, 13
...Adhesive, 14...Metal box, 15...Metallic flat plate electrode, 16...Sample, 17...Capacitor, 1
8... Electrometer. Agent Patent Attorney Nobuo Ogawa −

Claims (11)

[Claims] (1) A non-woven fabric layer including at least one synthetic fiber melt-blown non-woven fabric layer having a basis weight of 5 g/m^2 to 200 g/m^2, and substantially parallel to the fabric surface of the synthetic fiber melt-blown non-woven fabric layer. It consists of excipients present in
A filter element characterized in that the synthetic fiber melt-blown nonwoven fabric is substantially shaped into a peak-valley folded shape by folding the shaped article into a peak-valley fold. (2) The filter element according to claim 1, wherein the nonwoven fabric layer and the excipient are substantially integrated. (3) The filter element according to claim 1 or 2, wherein the excipient is made of a metal linear object. (4) The filter element according to claim 1 or 2, wherein the excipient is made of a metal mesh. (5) The filter element according to claim 3, characterized in that the metal linear object is coated with a synthetic resin. (6) The filter element according to claim 4, characterized in that the metal mesh is coated with a synthetic resin. (7) The filter element according to claim 1 or 2, characterized in that the excipient is a linear object made of synthetic resin. (8) The filter element according to claim 1 or 2, wherein the excipient is made of a synthetic resin net. (9) The synthetic fiber melt-blown nonwoven fabric has a surface charge density of 1
Claims 1, 2, and 3, characterized in that it is an electret nonwoven fabric with a density of ×10^-^1^0 clones/cm^2 or more.
, 4, 5, 6, 7 or 8. (10) Claims 1, 2, 3, 4, 5, 6, characterized in that the nonwoven fabric layer contains a spunbond nonwoven fabric.
, 7, 8 or 9. (11) In the nonwoven fabric layer, the surface charge density is 1.0×10^-
The filter according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, characterized in that an electret spunbond nonwoven fabric of ^1^0 clones/cm^2 or more is used in combination. element.