JP2015183340A - fiber structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber structure comprising a polyphenylene sulfide fiber having a flat multifoliate cross section, in which the improvement of dust detachability, the improvement of dust collection efficiency, and the reduction of pressure loss can be achieved without decreasing productivity upon filter cloth preparation.SOLUTION: There is provided a fiber structure comprising a polyphenylene sulfide fiber that has a flat multifoliate cross section and satisfies a flatness being defined as following expression (1) and a degree of deformation being defined as following expression (2): flatness (A/B)=2.0 to 3.0...(1); and degree of deformation (C/D)=1.0 to 5.0...(2).

Description

  The present invention relates to a fiber structure.

  Polyphenylene sulfide (hereinafter abbreviated as PPS) resin has properties suitable as engineering plastics such as excellent heat resistance, barrier properties, chemical resistance, electrical insulation properties and heat and moisture resistance, and injection. It is used for various electrical and electronic parts, machine parts and automobile parts, films, fibers, etc. mainly for molding and extrusion molding. For example, PPS resin materials are widely used for filter cloths used in various industrial filters such as bag filters for collecting waste gas dust. Such a filter cloth is obtained by laminating a fiber web made of PPS short fibers on a base fabric made from spun yarns of PPS short fibers and needle punching, collecting dust in waste gas, and collecting the dust. It is used to exhaust waste gas that does not contain, but it is important to keep the clogging free for a long period of time, and it is always desired to extend the filter cloth performance. .

  In order to suppress the clogging of the filter cloth and to prolong the life of the filter cloth performance, it is effective to detach the attached dust from the filter cloth efficiently. For example, if the filter cloth is clogged in the bag filter, the exhaust gas cannot be exhausted from the incineration facility. Therefore, the incineration facility must be stopped and the filter cloth must be replaced. That is, if the dust is efficiently removed before the filter cloth is clogged, the life of the filter cloth can be extended, and the incineration facility can be operated continuously for a long time.

  In a bag filter, a pulse jet method is often employed as a method for efficiently separating dust adhering to a filter cloth (see Patent Documents 1 and 2). With the pulse jet method, before the dust attached to the surface of the filter cloth accumulates, the filter cloth is vibrated by periodically blowing a high-speed air flow onto the filter cloth, and the dust attached to the surface of the filter cloth is removed. It is a method. Although such a pulse jet method enables dust to be removed, naturally, in this method, a high-speed air flow applied as an external force tends to decrease the mechanical strength of the filter cloth with time. This is because, when an external force is applied periodically, if the mechanical strength of the filter cloth and the dimensional stability of the filter cloth are insufficient, the filter cloth breaks and cannot function as a bag filter.

  On the other hand, environmental regulations are becoming more and more strict, especially in the United States, the regulations on particulate matter floating in the air that are particularly small (PM2.5 regulations) But it may apply. In response to such a flow, there is a demand for an excellent filter having higher dust collection efficiency and less clogging.

  To cope with this, PPS fibers having a single fiber fineness of 0.3 to 1.5 d (1.7 dtex) or less are arranged on the fiber web on the air inflow side, and the single fiber fineness exceeds 1.8 d (2.0 dtex). A filter cloth whose back side is composed of fibers has been proposed (see Patent Document 3). In this proposal, dust separation performance and dust collection efficiency are certainly improving, and the filter cloth is clogged. The pressure loss tends to decrease.

  In addition, a filter cloth including at least two layers of fiber webs and including 50 mass% or more of PPS fibers with a fiber diameter of 15 μm or less (single fiber fineness of 2.2 dtex or less) on the air inflow side is proposed. (See Patent Document 4). In this proposal, by regulating the fiber weight of 15 μm or less, a certain effect can be obtained in terms of dust separation performance, dust collection efficiency, and pressure loss due to clogging of the filter cloth.

  However, in any case, in order to achieve higher collection efficiency, it is necessary to make the inflow surface side single fiber finer finer. However, when using PPS fibers of 1 dtex or less, the filter cloth is not There is concern about the problem of low productivity.

As the above-mentioned correspondence, a filter cloth including a polyphenylene sulfide short fiber having a flat cross section has been proposed (see Patent Document 5). This proposal provides a high-efficiency dust collection bug filter that can efficiently filter dust in exhaust gas stably for a long period of time, and can suppress the decrease in strength compared to conventional felt. Although it has been described that the flatness is 2 to 6 and the cross-sectional shape has 3 to 5 circular portions on the long side, the actual situation is still insufficient.

Japanese Patent Laid-Open No. 08-103617 JP 09-248413 A Japanese Patent Laid-Open No. 10-165729 International Publication No. 2004/087293 JP 2008-161802 A

  The object of the present invention is to provide a bag filter felt made of polyphenylene sulfide fiber, which has good dust collection efficiency, can stably filter dust in exhaust gas for a long time with low pressure loss, and further reduces the productivity at the time of making filter cloth. An object of the present invention is to provide a fiber structure having a polyphenylene sulfide fiber having a flat multilobal cross section that can be produced without any problems.

  The present inventors considered that in order to have more efficient collection performance, it is necessary to maximize the fiber surface area for collecting dust. In other words, not only the flatness ratio and the number of long-side circumferential portions but also the degree of irregularity of the uneven portions in the cross-section are important, and intensive studies have been made.

That is, the present invention is as follows.
1. A fibrous structure having a polyphenylene sulfide fiber having a flat multilobal cross section that satisfies the flatness defined by the following formula (1) and the irregularity defined by the following formula (2).

Flatness (A / B) = 2.0 to 3.0 (1)
Deformation degree (C / D) = 1.0 to 5.0 (2)
2. 2. The fiber structure according to 1 above, wherein the fineness of the polyphenylene sulfide fiber having a flat multilobal cross section is 1.0 to 3.0 dtex.
3. 3. The fiber structure according to 1 or 2 above, wherein 10% by mass or more of the polyphenylene sulfide fiber having the flat multilobal cross section is contained.

  According to the present invention, a polyphenylene sulfide fiber having a flat multi-leafed cross section that has good dust collection efficiency while maintaining productivity at the time of filter fabric creation, and can stably filter dust in exhaust gas for a long time with low pressure loss. A fiber structure is provided.

FIG. 1 is a cross-sectional view of a polyphenylene sulfide fiber having a flat multilobal cross section used in the present invention. FIG. 2 is an exploded cross-sectional view of a filter material (filter cloth) using a nonwoven fabric made of polyphenylene sulfide fiber obtained in the present invention. FIG. 3 is a schematic side view of an atmospheric dust collection efficiency measuring apparatus using a filter material (filter cloth) made of polyphenylene sulfide fiber obtained by the present invention. FIG. 4 is a schematic side view of a pressure loss measuring apparatus after dust removal using a filter material (filter cloth) made of polyphenylene sulfide fiber obtained in the present invention.

  The details of the polyphenylene sulfide fiber having a flat multilobed cross section of the present invention will be described.

  The polyphenylene sulfide (PPS) resin used in the present invention means a polymer containing a phenylene sulfide unit such as a p-phenylene sulfide unit or an m-phenylene sulfide unit represented by the following structural formula (I) as a repeating unit. To do.

  The PPS resin may be a homopolymer or a copolymer having both p-phenylene sulfide units and m-phenylene sulfide units, and may be copolymerized with other aromatic sulfides as long as the effects of the present invention are not impaired. It may be a combination or a mixture.

  The PPS resin preferably has a weight average molecular weight of 30,000 to 90,000. When melt spinning is performed using a PPS resin having a weight average molecular weight of less than 30,000, the spinning tension may be low and yarn breakage may occur frequently during spinning, and if a PPS resin having a weight average molecular weight exceeding 90000 is used, The viscosity at that time is too high, and the spinning equipment must have a special high pressure resistance specification, which is disadvantageous because the equipment costs are high. A more preferred weight average molecular weight is 40,000 to 70,000.

  Examples of commercially available PPS resins used in the present invention include “Torelina” (registered trademark) manufactured by Toray Industries, Inc. and “Fortron” (registered trademark) manufactured by Polyplastics Co., Ltd.

  In FIG. 1, an example of the single fiber cross-sectional shape of the flat multileaf cross-section polyphenylene sulfide fiber used by this invention is shown.

  FIG. 1 illustrates a cross-sectional shape of a flat multileaf polyphenylene sulfide fiber provided in the spun yarn of the present invention having a plurality (eight) convex portions on the circumference of the fiber cross section.

  In the present invention, in the transverse shape, flat polyphenylene sulfide fibers having 6 or more convex portions are used, preferably 8 or more, and more preferably 10 or more.

  The flat multilobal cross-sectional polyphenylene sulfide fiber used in the present invention has a flat multilobal cross-sectional shape in the cross section of a single fiber, the flatness defined by the following formula (1) and the irregularity defined by the following formula (2) It is necessary to satisfy

Flatness (A / B) = 2.0 to 3.0 (1)
Deformation degree (C / D) = 1.0 to 5.0 (2)
Here, A is the maximum length of the cross section of the above-mentioned flat multi-leaf polyphenylene sulfide fiber. B is the maximum width of the cross section of the flat multi-leaf polyphenylene sulfide fiber, and is the length of the maximum width of the line segment connecting the vertices of the protrusions perpendicular to the length A of the line segment. C means the length of a line connecting the vertices of adjacent convex portions in the maximum uneven portion. D refers to the length of a perpendicular line extending from the line connecting the apexes of the adjacent convex portions to the bottom point of the concave portion in the maximum uneven portion.

  In the present invention, the flatness (A / B) is 2.0 to 3.0. When the flatness (A / B) is less than 2.0, the space on the surface of the fiber structure increases, and the dust collection performance tends to be inferior. On the other hand, when the flatness exceeds 3.0, the yarn-making property tends to deteriorate and the degree of deformity tends to deteriorate. The flatness (A / B) is more preferably 2.0 to 2.7, and still more preferably 2.0 to 2.5.

  The degree of irregularity (C / D) represents the size of the concave portion between the convex portions in the flat multilobal shape. When the value is large, the concave portion is small and the value is small. The recess means that it is large.

  In the present invention, the degree of profile is 1.0 to 5.0. If the degree of irregularity (C / D) is less than 1.0, the concave portion on the fiber surface tends to be bent, and the flat shape tends not to be maintained. Moreover, since a recessed part will become shallow when an irregularity degree (C / D) exceeds 5.0, it exists in the tendency for dust collection surface area to reduce and for dust collection efficiency to fall. The degree of profile (C / D) is more preferably 1.0 to 4.0, and still more preferably 2.0 to 4.0.

  The single fiber fineness of the flat multilobal polyphenylene sulfide fiber used in the present invention is preferably 3.0 dtex or less. More preferably, it is 2.0 dtex or less, More preferably, it is 1.7 dtex or less. Moreover, 1.0 dtex or more is preferable and 1.3 dtex or more is more preferable. When the single fiber fineness is less than 1.0 dtex, it tends to be easily wound around the card cylinder, and the process passability may be significantly lowered. On the other hand, if the single fiber fineness exceeds 3.0 dtex, the dust collection efficiency is inferior, and a sufficient dust filtering effect in the exhaust gas tends not to be obtained.

  Next, a method for producing the flat multi-leaf polyphenylene sulfide fiber and the round cross-section polyphenylene sulfide fiber of the present invention will be described. It can be obtained by the melt spinning method using the aforementioned resin. An undrawn yarn is obtained by extruding from a spinneret and spinning at a speed of 500 to 2000 m / min. At this time, it is necessary to use a hole having a shape corresponding to the cross section to be obtained. The obtained undrawn yarn was drawn 1.1 to 4.0 times by a conventional method, then crimped with a crimper, and cut into a predetermined length to obtain a flat multi-leaf polyphenylene sulfide fiber. Can be obtained.

  FIG. 2 is an exploded cross-sectional view of a fiber structure (filter cloth) using a nonwoven fabric made of polyphenylene sulfide fiber obtained in the present invention.

  The fiber structure of the present invention preferably contains 10% by mass or more of the flat multi-leaf polyphenylene sulfide fiber of the present invention based on the fiber structure. More preferably, it is 15 mass% or more.

  In FIG. 2, the fiber web 1 that forms the filtration layer on the air inflow surface refers to the surface of the filter material for surface filtration where the air containing dust first comes into contact with the filter material. That is, it indicates a surface on which dust is collected on the filter material surface to form a dust layer. The flat multilobal polyphenylene sulfide fiber of the present invention is used for this fiber web 1. Moreover, the surface on the opposite side is formed by the fiber web 3 that forms the filtration layer of the air discharge surface, and indicates the surface from which the air from which dust has been removed is discharged. Further, a woven fabric (aggregate) 2 made of heat-resistant fibers is sandwiched between the fiber web 1 and the web 3 and made into a felt by a needle punching process, thereby providing mechanical properties such as dimensional stability, tensile strength and wear resistance. It becomes possible to obtain a filter material having excellent strength and dust collection efficiency.

  The polyphenylene sulfide fiber obtained by the method for producing the polyphenylene sulfide fiber of the present invention is not only a nonwoven fabric such as a bag filter and papermaking, but also once a spun yarn, and the spun yarn can be used to make a fabric such as a woven fabric or a knitted fabric. it can.

  Next, the manufacturing method of the flat multilobal polyphenylene sulfide fiber of this invention is demonstrated concretely by an Example. The present invention is not limited by the following examples. Each characteristic value defined in the present invention is obtained by the following method.

(1) Card passability The state of occurrence of fluff from the card doffer at the time of making the felt and the slipping state of the web were visually confirmed. The amount of fluff generation and the case where there was no slippage of the web were very good, ◎, the case where the amount was relatively small, ◯, the case where it was large, and △ as the middle.

(2) Air dust collection efficiency:
The dust collection efficiency of the filter material was measured by the atmospheric dust calculation method using the atmospheric dust collection efficiency measuring device shown in FIG. That is, in FIG. 3, the blower 8 installed on the downstream side of the filter material 5 (φ170 mm) is allowed to aerate the filter material 5 with an air flow having a filtration wind speed of 1 m / min for 5 minutes, and then the upstream side of the filter material 5. The number A of atmospheric dust (particle size: 0.3-5 μm) was measured by a particle counter (upstream) 4 manufactured by Rion, and the number B of atmospheric dust (particle size: 0.3-5 μm) downstream of the filter 5 was simultaneously measured. Measured with a particle counter (downstream) 6 manufactured by the same company. The measurement sample was n = 3. From the obtained measurement results, the collection efficiency (%) was determined by the following formula.
・ (1- (BA)) × 100
In the above formula, A is the number of upstream atmospheric dust and B is the number of downstream atmospheric dust.

  The criteria for air dust collection efficiency are: dust collection efficiency with a particle size of 1 μm or less is 55% or more, ◯ is 50% or more and less than 55% (good), and 45% or more and less than 50% is △ (somewhat good). , Less than 45% was taken as x (bad). ○ (Good) or better was accepted.

(3) Pressure loss after dust removal:
The pressure loss after dust removal was measured from the pressure loss measuring device of FIG. That is, in FIG. 4, an air flow having a filtration wind speed of 2.0 m / min was given to the filter material 5 by the vacuum pump 12 and the flow meter 10 installed on the downstream side of the filter material 5 (φ170 mm). 10 kinds of JIS test powder 1 (fly ash) dust (manufactured by Japan Powder Industrial Technology Association), dust adjusted to a dust concentration of 20 g / m 3 with a dust feeder 14 and a dust disperser 15, filter material 5 (filtration area of 100 cm ² ) was added to the air inflow side. Every time the pressure loss measured with the digital manometer 13 increases to 10 mmH ₂ O (980 pa), the pulse jet pressure machine 3 downstream of the filter 5 causes a pulse jet pressure of 3 kgf / cm ² (294 kpa), 0.1 sec. The pressure jet immediately after the pulse jet loading was continuously monitored with the digital manometer 13.

Criteria pressure loss after flicked dust, less than the elapsed time 30hr time point of pressure loss 6mmH ₂ O (60pa) _◎, the ○ (good) less than 6mmH 2 O (60pa) or _7mH 2 O _(69pa), 7 mmH ₂ O (69 pa) or more and 8 mmH ₂ O (78 mH ₂ O) or less was evaluated as Δ (slightly good) and higher than 8 mmH ₂ O (78 pa) as x (bad). ○ (Good)

(4) Comprehensive judgment:
In the above criteria for determining card passage, air dust collection efficiency, and pressure loss after dust removal, if there is at least one x (bad) judgment, the overall judgment is x (bad). If there is more than one item of △ (somewhat good) among the three items, the overall judgment is △ (somewhat good). If there is no △ (somewhat good) and × (bad) among the three items, the overall judgment is ◯. . ○ (Good)

(5) Flatness and profile A single fiber was taken out, and 20 arbitrary cross sections cut perpendicular to the longitudinal direction of the single fiber were photographed with a microscope AFX-DX manufactured by Nikon Corporation, and leaves were taken from the photograph of the photographed cross section. The number of parts and the length of each part of A, B, C, D were measured and calculated using the above formulas (1) and (2).

(6) Fineness The fineness was measured according to JIS L1015 (2010).

[Example 1]
Using PPS short fibers with a single fiber fineness of 3.0 dtex and a cut length of 76 mm (“Torcon” (registered trademark) S101-3.0T76 mm, manufactured by Toray Industries, Inc.), a single yarn count of 20 s and a spun yarn with two combined yarns ( A total fineness of 600 dtex) was obtained. Using this spun yarn, a plain weave fabric was woven to obtain a plain fabric made of PPS spun yarn having a warp density of 26 / 2.54 cm and a cotton yarn density of 18 / 2.54 cm. Using this plain woven fabric as an aggregate, PPS short fibers (flatness) having a round cross-section fiber fineness of 2.2 dtex and a flat multi-leaf cross-section fiber fineness of 1.5 dtex obtained on a single side by mass mixing at a mass ratio of 80:20. : 2.5, Deformity: 3.0)
Was carded with an opener, and then a fiber web obtained by temporary needle punching at a needle needle density of 50 / cm ² was laminated with a basis weight of 194 g / m ² . This fiber web forms a filtration layer on the air inflow surface. On the other side of the woven fabric, 100% of PPS short fibers (Torucon (registered trademark) S101-7.8T51mm manufactured by Toray Industries, Inc.) with a single fiber fineness of 7.8 dtex and a cut length of 76 mm are treated with an opener and a carding treatment. After that, a fiber web obtained by temporary needle punching at a needle needle density of 50 / cm ² was laminated with a basis weight of 220 g / m ² . This fiber web forms a filtration layer on the air discharge surface. Further, the fabric (aggregate) and the above-described fiber web were entangled by needle punching to obtain a filter having a basis weight of 544 g / m ² and a total needle density of 300 needles / cm ² . Table 1 shows the performance of the obtained filter material. The filter material obtained here contracted by the needle punching process, and there was a tendency for the basis weight to be higher than theoretically.

[Example 2]
As fibers constituting the fiber web on the air inflow surface side, PPS short fibers having a round cross-section fiber fineness of 2.2 dtex and a flat multileaf cross-section fineness of 1.5 dtex (flatness: 2.5, irregularity degree: 3. A filter material was obtained in the same manner as in Example 1 except that 0) was mixed at a mass ratio of 50:50. The performance of the obtained filter material is shown in Table 1.

[Example 3]
As fibers constituting the fiber web on the air inflow surface side, PPS short fibers having a round cross-section fiber fineness of 2.2 dtex and a flat multi-leaf cross-section fiber fineness of 2.2 dtex (flatness: 2.5, irregularity: 3.0) was obtained in the same manner as in Example 1 except that the fiber was mixed at a mass ratio of 80:20. The performance of the obtained filter material is shown in Table 1.

[Comparative Example 1]
As fibers constituting the fiber web on the air inflow surface side, PPS short fibers having a round cross-section fiber fineness of 1.0 dtex and PPS short fibers having a round cross-section fiber fineness of 2.2 dtex are mixed at a mass ratio of 20:80. A filter material was obtained in the same manner as in Example 1 except that after opening the fiber, an opener and carding were performed. Table 1 shows the performance of the obtained filter material.

[Comparative Example 2]
As fibers constituting the fiber web on the air inflow side, PPS short fibers having a round cross-section fiber fineness of 1.0 dtex and PPS short fibers having a round cross-section fiber fineness of 2.2 dtex are mixed at a mass ratio of 50:50. A filter material was obtained in the same manner as in Example 1 except that after opening the fiber, an opener and carding were performed. Table 1 shows the performance of the obtained filter material.

[Comparative Example 3]
The same method as in Example 1 except that PPS short fibers having a round cross-section fiber fineness of 2.2 dtex were subjected to an opener and carding treatment as fibers constituting the fiber web on the air inflow surface side. A filter material was obtained. Table 1 shows the performance of the obtained filter material.

1: Fiber web forming a filtration layer on the air inflow surface 2: Fabric made of heat-resistant fibers (aggregate)
3: Fiber web forming the filtration layer on the air discharge surface 4: Particle counter (upstream)
5: Filter material 6: Particle counter (downstream)
7: Manometer 8: Blower 9: Pulse jet load machine 10: Flow meter 11: Dust collection filter 12: Vacuum pump 13: Digital manometer 14: Dust feeder 15: Dust disperser 16: Dust collection part 17: Atmospheric dust air 18: Air from which atmospheric dust has been removed 19: Weighed dust 20: Air containing dust 21: Air from which dust has been removed

Claims (3)

A fibrous structure having a polyphenylene sulfide fiber having a flat multilobal cross section that satisfies the flatness defined by the following formula (1) and the irregularity defined by the following formula (2).
Flatness (A / B) = 2.0 to 3.0 (1)
Deformation degree (C / D) = 1.0 to 5.0 (2)   2. The fiber structure according to claim 1, wherein the fineness of the polyphenylene sulfide fiber having a flat multilobal cross section is 1.0 to 3.0 dtex. 3. The fiber structure according to claim 1, wherein the polyphenylene sulfide fiber having a flat multilobed cross section is contained in an amount of 10% or more.