JP2019099959A - Polyphenylene sulfide fiber and fiber structure - Google Patents

Abstract

To provide a polyphenylene sulfide fiber capable of keeping more efficient collecting performance without decreasing productivity upon filter cloth preparation, in a felt for a bag filter, and fiber structure having the fiber.SOLUTION: There is provided a polyphenylene sulfide fiber having the number of crimp of 10-15 crimps/25 mm and crimp frequency ratio defined as following expression (1). Expression (1): -0.07N+2.1≤Y≤-0.07N+2.3, N=number of crimp, Y=crimp frequency ratio. In the expression, N represents number of crimp, and Y represents crimp frequency ratio. The crimp frequency ratio is shown in the expression (2). Expression (2):Y(crimp frequency ratio)=crimp ratio (%)/number of crimp (crimps/25 mm).SELECTED DRAWING: None

Description

  The present invention relates to polyphenylene sulfide fibers and fiber structures.

  Polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) resin has properties suitable as engineering plastics such as excellent heat resistance, barrier property, chemical resistance, electrical insulation and moisture and heat resistance, and injection In addition to various electric and electronic parts, machine parts and automobile parts mainly for molding and extrusion molding, it is used for films, fibers and the like. PPS is used as a fiber with excellent heat resistance and chemical resistance because it is a thermoplastic polymer with high crystallinity and excellent heat resistance. For example, it is used for various industrial filters such as bag filters for waste gas dust collectors. PPS fiber materials are widely used as filter cloths to be used. Such a filter cloth is obtained by laminating and needlepunching a fiber web consisting of PPS short fibers on a base cloth made of spun yarn of PPS short fibers, and collecting dust in waste gas and dusting the dust It is used to evacuate waste gas that does not contain it, but it is important to keep the condition free from clogging for a long time, and it is always desirable to extend the life of such filter cloth performance .

  In order to suppress the clogging of the filter cloth and to prolong the life of the filter cloth, it is effective to efficiently separate the attached dust from the filter cloth. That is, if the filter cloth is clogged in the bag filter, exhaust gas from the incinerator can not be exhausted, so the incinerator must be stopped to replace the filter cloth, but before the filter cloth clogs. If the dust is efficiently removed, the filter cloth can be made to have a longer life, and the incinerator can be operated continuously for a long time.

  In the bag filter, a pulse jet method is often employed as a method for efficiently removing dust attached to the filter cloth. In the pulse jet method, a high velocity air stream (pulse jet) is periodically blown to the filter cloth to vibrate the filter cloth while dust attached to the surface of the filter cloth is not accumulated excessively, and the filter cloth is vibrated on the surface of the filter cloth. It is a method of removing the adhering dust. Since this pulse jet is at high pressure, the filter cloth of the bag filter is required to have a filter strength that can last. On the other hand, environmental regulations are becoming stricter, there is a need for an excellent filter with higher dust collection efficiency and less clogging.

  The cardability and spinnability are extremely important in order to obtain a high-performance filter excellent in filter strength and collection performance as described above. However, PPS has higher friction resistance to metal and fiber compared to polyester and nylon, etc., and it is in a trend where strength is required for the purpose of extending the life of the bag filter, and high crystal for high strength. The present situation is that it is difficult to apply crimp due to The crimp of the fiber greatly affects the card passing property, and therefore, various studies have been made to obtain a good card passing property, particularly for the crimp.

  As a means for improving cardability, in Patent Document 1, a treatment agent containing 50% by weight or more of an alkyl phosphate alkali metal salt as an active ingredient is added, and a fiber having a certain crimp number and a crimp rate or more is used It has been proposed to do. Further, in Patent Document 2, it is proposed that tensile strength and a crimp elastic modulus be defined as a countermeasure against deterioration of processability due to sufficient entanglement between fibers not being sufficiently performed due to crimp in the carding process. . Further, in Patent Document 3, it is proposed to define a crimp degree in order to obtain sufficient mechanical strength as a filter cloth for bag filters by sufficiently entangling fibers.

Japanese Patent Application Publication No. 03-14618 JP 2008-226869A Unexamined-Japanese-Patent No. 2004-261760

  However, with regard to Patent Document 1, there is assumed a case where the card passability is inferior, such as neps, etc., with no upper limit on the crimp frequency. Moreover, in patent document 2, the possibility that the trouble resulting from the number of crimps, such as a fly and a nept, generate | occur | produces only by prescribing | regulating tensile strength and a crimp elastic modulus is not enough. Furthermore, in Patent Document 3, it was actually difficult to obtain good cardability only by defining the crimp degree.

  Therefore, it is an object of the present invention to provide a felt for a bag filter for polyphenylene sulfide fiber, which is a fiber for maintaining excellent collection performance and more efficient collecting performance without reducing productivity at the time of producing a filter cloth, and the fiber It is an object of the present invention to provide a fiber structure having

  As a result of intensive investigations, the inventors of the present invention have found that the crimp of the constituent fibers is made to obtain a filter cloth having excellent strength and more efficient collection performance without reducing productivity at the time of filter cloth production. It has been found that the number and the correlation between the crimp number and the crimp frequency ratio are important, and it is important to use a fiber satisfying the following formula.

That is, the present invention is as follows.
1. Polyphenylene sulfide fiber having a crimp number of 10 to 15 peaks / 25 mm and having a crimp frequency ratio satisfying the following formula (1).
Formula (1): −0.07 N + 2.1 ≦ Y ≦ −0.07 N + 2.3
N = number of crimps Y = crimp frequency ratio Here, N is the number of crimps, Y is the crimp frequency ratio, and the crimp frequency ratio is represented by equation (2).
Formula (2): Y (crimping frequency ratio) = crimp degree (%) / crimp number (peak / 25 mm)
2. The fiber according to claim 1, which has a strength of 4.0 to 5.5 cN / dtex.

3. The fiber according to 1 above, which has a single fiber fineness of 0.9 to 3.0 dtex.
4. A fiber structure comprising 40% by mass or more of the polyphenylene sulfide fiber according to any one of claims 1 to 3.

  According to the present invention, in a felt for a bag filter of polyphenylene sulfide fiber, a fiber structure made of polyphenylene sulfide fiber which is excellent in strength and has a more efficient collecting performance without reducing productivity at the time of producing a filter cloth, In particular, a bag filter felt of polyphenylene sulfide fiber can be obtained.

It is a disassembled sectional view of the filter material (filter cloth) using the nonwoven fabric which consists of polyphenylene sulfide fiber obtained by the present invention. It is a schematic side view of the atmospheric dust collection efficiency measuring device which used the filter material (filter cloth) used in the example.

  The polyphenylene sulfide fiber of the present invention will be described in detail.

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

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

  Moreover, it is preferable that PPS resin is 30000-60000 in weight average molecular weight. When melt spinning is performed using a PPS resin with a weight average molecular weight of less than 30,000, yarn breakage may occur frequently during spinning because the spinning tension is low, and when using a PPS resin with a weight average molecular weight of more than 60000, melting occurs. When the viscosity is too high, it is necessary to set the spinning equipment to a special high pressure specification, which is disadvantageous because the equipment cost is high. A more preferable weight average molecular weight is 35,000 to 55,000.

  As a commercial item of PPS resin used by this invention, Toray Industries, Inc. product "Torelina" (registered trademark), Polyplastics Co., Ltd. product "Durafide" (registered trademark) etc. are mentioned.

The polyphenylene sulfide fiber of the present invention is required to have a crimp number ratio of 10 to 15 peaks / 25 mm, and a crimp frequency ratio satisfying the following formula (1).
Formula (1): −0.07 N + 2.1 ≦ Y ≦ −0.07 N + 2.3
N = number of crimps Y = number of crimps ratio where N is the number of crimps and Y is a ratio of crimps.

The crimp frequency ratio is defined by equation (2).
Formula (2): Y (crimping frequency ratio) = crimp degree (%) / number of crimps (peak / 25 mm).

  In the present invention, the number of crimps is 10 to 15 peaks / 25 mm. More preferably, it is 11-14 mountain / 25 mm, More preferably, it is 12-14 mountain / 25 mm. If the number of crimps is less than 10 peaks / 25 mm, the interlacing property between fibers is poor, and fly and web breakage may occur in the curd process, and the process passability may be significantly reduced. In addition, if the crimp number is 16 peaks / 25 mm or more, neps will occur and a web with excellent surface quality can not be obtained. The number of crimps in the present invention refers to a value measured by the method described later.

  Furthermore, in the present invention, it is important that the crimp frequency ratio shown in Formula (2) is within the specified range of Formula (1). If the crimp ratio is too low, web entanglement is lowered and web breakage is likely to occur, and it is difficult to obtain a web with excellent surface quality in addition to poor productivity. Further, when the crimp ratio is too high, it is not preferable because the fibers are strongly entangled, which causes neps during the production to deteriorate the productivity and causes deterioration of the surface quality.

  The strength of the polyphenylene sulfide fiber of the present invention is preferably 4.0 to 5.5 cN / dtex, more preferably 4.5 to 5.5 cN / dtex, still more preferably 4.5 to 5.0 cN / dtex is there. By setting the strength to 4.5 cN / dtex or more, it is possible to reduce the possibility of the filter cloth being broken by the pulse jet that shakes off the dust attached to the filter cloth, and it can withstand the use under long-term high temperature PPS fiber can be obtained. Further, by setting the strength to 5.5 cN / dtex or less, the degree of crystallinity is high and the rigidity of the single fiber is too high, and the number of crimps does not easily decrease.

  The single fiber fineness of the polyphenylene sulfide fiber of the present invention is preferably 0.9 to 3.0 dtex, more preferably 0.9 to 2.0 dtex. If the single fiber fineness is 0.9 dtex or more, the tendency of the card cylinder to be easily wound can be suppressed, and the process passability (card passability) is not significantly reduced. In addition, if the single fiber fineness is 3.0 dtex or less, the dust collection efficiency is poor, and it is not possible to obtain a sufficient dust filtration effect in the exhaust gas.

  In the method for obtaining the polyphenylene sulfide fiber of the present invention, it is important how to disperse the tow after drawing into a single fiber to make the single fiber in a state of being easily buckled. Although a method such as kneading a lubricant into a polymer may be mentioned, a method of obtaining an oil agent is most preferable in consideration of productivity and the like. The oil agent is not particularly limited as long as it is a process oil agent used for fiber production, and any of nonionic surfactant, cationic surfactant, anionic surfactant and the like can be preferably used.

  Next, an example of the method for producing the polyphenylene sulfide fiber of the present invention will be specifically described. The polyphenylene sulfide fiber of the present invention can be obtained by melt spinning using the above-described PPS resin. The PPS resin is extruded from a spinneret and spun at a speed of 500 to 2000 m / min to obtain an undrawn yarn. At this time, it is necessary to use the hole shape of the die corresponding to the cross section to be obtained. The obtained undrawn yarn is drawn to 1.1 to 4.0 times by an ordinary method, and then an oil agent is applied to the yarn relaxed by the fixed length heat treatment, and the temperature is 180 ° C. or higher, preferably 200 ° C. or higher and preferably 240 ° C. Apply crimp and heat setting in a stuffing box type crimper filled with steam as follows. By adopting such conditions when applying crimp, the short fiber finally obtained can satisfy the range defined in the present invention. In order to fix the crimped state to the yarn of polyphenylene sulfide fiber that has already been crystallized by fixed-length heat treatment, it is important to adopt a temperature above fixed-length heat treatment as the temperature at the time of crimp application. If it is too high, fusion of fibers may occur. Following application of the crimp, if necessary, an oil may be applied and cut into a predetermined length to obtain polyphenylene sulfide fiber.

  Next, the fiber structure of the present invention will be described.

  FIG. 1 is an exploded cross-sectional view of a fiber structure (filter cloth) using a nonwoven fabric made of polyphenylene sulfide fibers of the present invention.

  The fiber structure of the present invention preferably contains the polyphenylene sulfide fiber of the present invention at 40% by mass or more based on the total mass of the fiber structure. More preferably, it is 50 mass% or more.

  In FIG. 1, the fiber web 1 which forms the filtration layer of an air inflow surface shows the thing of the filter material of surface filtration in which the air in which the dust was contained contacts a filter material first. That is, it indicates the surface on which the dust is collected on the surface of the filter material to form a dust layer. The polyphenylene sulfide fiber of the present invention is used for the fiber web 1. Further, the opposite surface is formed of a fiber web 3 made of heat-resistant fibers forming the filtration layer of the air discharge surface, and indicates the surface from which air from which dust has been removed is discharged. Also, by sandwiching the fabric (aggregate) 2 made of heat resistant fibers between the fiber web 1 and the fiber web 3 and forming a felt in the needle punching process, machines such as dimensional stability, tensile strength and abrasion resistance It is possible to obtain a filter material which is excellent in target strength and dust collection efficiency.

  In the fiber structure containing polyphenylene sulfide fiber of the present invention, the polyphenylene sulfide fiber of the present invention is once used as a spun yarn other than non-woven fabric such as bag filter and paper making, and fabrics such as woven fabric or knitted fabric using the spun yarn Also included.

  EXAMPLES Next, the polyphenylene sulfide fiber of the present invention is specifically described by way of examples, but the present invention is not limited by these examples. Each characteristic value defined in the present invention is obtained by the following method.

(1) Number of crimps and crimp degree A sample was randomly taken out of 10 unopened parts per single unopened part, and a total of 10 single fibers were sampled. The number of peaks on one side of these ten single fibers is read using a magnifying glass, and the average value (n = 10) is defined as the number of peaks on one side per one short fiber. Next, one end of this short fiber is fixed, a load of 2.2 mg / dtex (2 mg / d) and 333 mg / dtex (300 mg / d) is applied to the other end, and the fiber length at that time is measured respectively The number of crimps and the degree of crimp are calculated by
Number of crimps (mountain / 25 mm) = 25a / A
Crimp degree (%) = 100 (B-A) / B
However, a, A, and B are as follows.
a: The number of one side ridges per one staple fiber A: Fiber length when a load of 2 mg / d is applied (mm)
B: Fiber length (mm) when a load of 300 mg / d was applied.

(2) Cylinder winding A web of 20 g / m ² and 50 cm in width was carded at a speed of 30 m / min for 1 hour with a roller card under conditions of 25 ° C. and 65% RH. The wound condition to the cylinder at the time of felt preparation and the occurrence of fly cotton from the card doffer were visually confirmed. As for the winding on the cylinder roller, no roller winding was observed, and a very good state was ◎, a case of 1 or less was ○, and a case of 2 or more and 3 or more was x.

(3) Curd Nep A web of 20 g / m ² and 50 cm in width was carded at a speed of 30 m / min for 1 hour with a roller curd at 25 ° C. and 65% RH. With regard to the state of occurrence of neps in the carded web at the time of felt preparation, the number of neps obtained by sampling a 1-m sample every 10 minutes in the longitudinal direction was visually confirmed for the carded web. A very good state without neps was ◎, a case of 10 or less was ○, and a case of exceeding 11 was x.

(4) Curd fly A web of 20 g / m ² and 50 cm in width was carded at a speed of 30 m / min for 1 hour with a roller curd at 25 ° C. and 65% RH. The amount of fly (cotton) generation on the card at the time of felt preparation is ◎, the case of more than 10 g and less than 30 g is ○, and the case of 30 g or more is x.

(5) Felt strength Three 20 cm × 20 cm samples were prepared by the method of JIS-L 1085 (1998) using the polyphenylene sulfide fibers obtained in the respective examples and comparative examples. The weight of the sample was measured, and the average value was determined as the mass per m2. The felt thickness was randomly measured at 10 points with a thickness dial gauge (pushing pressure 250 g / cm ² = 0.000245 Pa), and the average value was calculated. The felt strength was calculated in the vertical direction and in the horizontal direction, respectively, as an average value of five samples of the test pieces of the felt, using a constant-speed stretch-type tensile tester. As criteria for judging the felt strength, the numerical value of felt strength in the horizontal direction is 1900 for 1900 N / 5 cm or more, ○ (good) for 1700 N / 5 cm or more and less than 1900 N / 5 cm, and x (bad) for 1700 N / 5 cm.

(6) Atmospheric Dust Collection Efficiency The dust collection efficiency of the filter material obtained in each of the Examples and Comparative Examples was measured by the atmospheric dust calculation method using the atmospheric dust collection efficiency measuring device of FIG. That is, in FIG. 2, the air flow of 1 m / min of filtered air velocity is allowed to flow through the filter material 5 for 5 minutes by the blower 8 installed downstream of the filter material 5 (φ 170 mm). The number A of atmospheric dust (particle size: 0.3 to 5 μm) is measured by a particle counter (upstream) 4 manufactured by Rion Co., and simultaneously, the number B of atmospheric dust (particle size: 0.3 to 5 μm) on the downstream side of the filter 5 It measured by the particle counter (downstream) 6 made in the company. The measurement sample was performed at n = 3. From the obtained measurement results, the collection efficiency (%) was determined by the following equation.
Collection efficiency (%) = (1-(B-A)) x 100
In the above equation, A is the number of upstream air dust, and B is the number of downstream air dust.

  The criteria for determining the atmospheric dust collection efficiency were: 55% or more for dust collection efficiency with a particle diameter of 1 μm or less, ((good) for 50% or more and less than 55%, and x (poor) for less than 50%. ○ (Good) I passed the exam.

(7) Comprehensive judgment:
In the judgment criteria of the above card passability (cylinder wound, card nept, curd fly), atmospheric dust collection efficiency and felt strength, if there is even one of the five (bad) judgments among the five items, the overall judgment is It was regarded as x (bad), and all 5 items were evaluated as ○ (good) or more. Furthermore, when all five items were all ○ (good) or more and ◎ was three or more items, the comprehensive judgment was を.

(8) Single fiber fineness Single fiber fineness was measured according to JIS L1015 (2010).

Example 1
First, the high crimped polyphenylene sulfide fiber of the present invention was produced by the method described below.

After performing vacuum drying for 5 hours at a temperature of 160 ° C, PPS pellet E2280 (melt flow rate: 165 g / 10 min) manufactured by Toray Industries, Inc. is supplied to a pressure melter type melt spinning machine, and single hole discharge amount Melt spinning was carried out at 0.55 g / min, a conventional spinning oil for PPS was added as a focusing agent, and it was taken at a take-up speed of 900 m / min to obtain a PPS undrawn yarn. The melt spinning temperature was controlled by setting the temperature of the lower part of the pack housing to 320 ° C. and the temperature of the lower part of the pack housing at 310 ° C. The cooling chimney temperature was 25 ° C., and the wind speed was 55 m / min. The obtained undrawn yarn is drawn at a draw ratio of 3.4 times in warm water at 95 ° C., and after fixed-length heat treatment, 0.10 weight percent of a nonionic surfactant is applied to the tow, and steam is obtained. the tow tow temperature reached 90 ° C. at conditioner, a nip pressure of 4.0 kg / ^cm 2 G, and at the same time crimped in crimper conditions stuffing pressure 1.0 kg / cm ² G, steam temperature 200 ° C. The crimp was applied with a stuffing box-type crimper filled. After that, drying was carried out, and after applying an oil solution, it was cut into a length of 51 mm to obtain the polyphenylene sulfide fiber (fineness 2.2 dtex) of the present invention.

  On the other hand, using a PPS short fiber with a single fiber fineness of 2.2 dtex and a cut length of 51 mm (Toray Industries, Inc. “Torcon” (registered trademark) S371-2.2T51 mm), spinning with a single yarn count of 20s and 2 yarns A yarn (total fineness 600 dtex) was obtained. A woven fabric having a plain weave structure was woven using this spun yarn to obtain a plain woven fabric composed of PPS spun yarn having a warp density of 26 / 2.54 cm and a cotton yarn density of 18 / 2.54 cm.

This plain weave fabric was used as an aggregate on the single side thereof, and the fineness 2.2 dtex and strength 4.5 cN / detx of the normal crimped base cotton obtained by mixed fiber at a mass ratio of 50: 50 were obtained in this example. A high density crimped raw cotton with a fineness of 2.2 dtex, a strength of 4.5 cN / dtex, a crimp number of 10 peaks / 25 mm, and a crimp ratio of 1.4 PPS short fibers treated with an opener and having a needle density of 50 A fiber web obtained by temporary needle punching at 1 / cm ² was laminated at a basis weight of 194 g / m ² . This fibrous web forms the filtration layer of the air inflow surface. On the other side of the woven fabric (aggregate), opener is 100% PPS short fiber with a single fiber fineness of 7.8 dtex and a cut length of 76 mm (Toru Co., Ltd. “Torkon” (registered trademark) S101-7.8T51 mm) 100% After carding, the fiber web obtained by temporary needle punching at a needle density of 50 / cm ² was laminated at a basis weight of 220 g / m ² . This fibrous web forms the filtration layer of the air outlet surface. Furthermore, the woven fabric (aggregate) and the above-mentioned fiber web were entangled by needle punching, and a filter with a basis weight of 544 g / m ² and a total needle density of 300 / cm ² was obtained.

  The performance of the obtained filter material (air dust collection efficiency) is shown in Table 1. The filter material obtained here was shrunk by needle punching, and the theoretical basis of the film weight tended to be higher.

Example 2
In the PPS short fiber manufacturing method of Example 1, the crimp number 15 corrugations / 25 mm, crimp frequency ratio 1 by changing the stuffing pressure of the crimper from 1.0 kg / cm ² G to 2.0 kg / cm ² G A PPS staple fiber of .2 was obtained, and a filter material was obtained in the same manner as in Example 1 using this PPS staple fiber. The performance of the obtained filter material is shown in Table 1.

[Example 3]
In the PPS short fiber production method of Example 1, the crimping number ratio 13 crimps / 25 mm, crimp frequency ratio 1 by changing the stuffing pressure of the crimper from 1.0 kg / cm ² G to 1.5 kg / cm ² G A PPS staple fiber of .3 was obtained, and a filter material was obtained in the same manner as in Example 1 using this PPS staple fiber. The performance of the obtained filter material is shown in Table 1.

Example 4
In the PPS short fiber production method of Example 1, the strength is 4.8 cN / dtex, and the justification pressure of the crimper is 2.0 kg / cm ² G by changing the draw ratio from 3.4 times to 3.5 times. By changing this, PPS short fibers having a crimp number of 15/25 mm and a crimp frequency ratio of 1.2 were obtained, and using this PPS short fibers, a filter material was obtained in the same manner as in Example 1. The performance of the obtained filter material is shown in Table 1.

[Example 5]
In the PPS short fiber manufacturing method of Example 1, the strength is 4. by changing the single hole discharge amount to 0.30 g / min, changing the fineness to 1.2 dtex, and the draw ratio to 3.5 times. By changing the stuffing pressure of 8 cN / dtex and crimper to 2.0 kg / cm ² G, PPS short fibers of 15 crimps / 25 mm, crimp ratio 1.2 are obtained, and this PPS short fibers are used A filter material was obtained in the same manner as in Example 1. The performance of the obtained filter material is shown in Table 1.

[Example 6]
In the PPS short fiber manufacturing method of Example 1, the strength is 4 by changing the single hole discharge amount to 0.30 g / min, and by making the fineness 1.2 dtex and the draw ratio 3.5 times. A PPS short fiber having a crimp number of 15 peaks / 25 mm and a crimp ratio of 1.2 was obtained by changing the stuffing pressure of the crimper to 2.0 kg / cm ² G at 8 cN / dtex. A filter material was obtained in the same manner as in Example 1 except that the blended ratio of high-crimped raw cotton was increased to 80% using this PPS short fiber. The performance of the obtained filter material is shown in Table 1.

[Example 7]
In the method of producing PPS short fibers of Example 1, the strength is set to 4.4 by changing the single hole discharge amount to 0.70 g / min, and changing the fineness to 2.8 dtex and the draw ratio to 3.3 times. By changing the stuffing pressure of 2cN / dtex and crimper to 1.5 kg / cm ² G, a PPS short fiber of 13 crimps / 25 mm and a crimp ratio of 1.3 is obtained, and this PPS short fiber is used A filter material was obtained in the same manner as in Example 1. The performance of the obtained filter material is shown in Table 1.

Comparative Example 1
In the PPS short fiber manufacturing method of Example 1, the stuffing pressure of the crimper is changed to 2.0 kg / cm ² G, the temperature of the steam filled in the stuffing box is changed to 250 ° C., crimp number 15 corrugations / 25 mm, crimp A PPS short fiber having a frequency ratio of 1.6 was obtained, and a filter material was obtained in the same manner as in Example 1 using this PPS short fiber. The performance of the obtained filter material is shown in Table 2.

Comparative Example 2
In the PPS short fiber production method of Example 1, PPS short fibers are obtained in the same manner as in Example 1 except that 0.10% by weight of a nonionic surfactant is not added to the tow, and this PPS short fiber is used to carry out. A filter material was obtained in the same manner as in Example 1. The performance of the obtained filter material is shown in Table 2.

Comparative Example 3
In the method of producing PPS short fibers of Example 1, the temperature of the steam filled in the stuffing of the crimper is changed to 150 ° C. to obtain PPS short fibers having a crimp ratio of 1.1, and the draw ratio is 3.2 times By changing, a PPS short fiber having a strength of 3.8 cN / dtex was obtained, and a filter material was obtained in the same manner as in Example 1 using this PPS short fiber. The performance of the obtained filter material is shown in Table 2.

Comparative Example 4
In the PPS short fiber manufacturing method of Example 1, the strength is 3.3 by changing the single hole discharge amount to 1.00 g / min, and changing the fineness to 4.0 dtex and the draw ratio to 3.2 times. By changing the steam temperature filled in the stuffing of the crimper to 150 ° C. at 8 cN / dtex, a PPS short fiber with a crimp number ratio of 1.1 was obtained. A filter material was obtained in the same manner as in Example 1 except that the blended ratio of high crimped raw cotton was reduced to 20% using this PPS short fiber. The performance of the obtained filter material is shown in Table 2.

1: Fiber web forming the filtration layer of the air inflow surface 2: Textile made of heat resistant fibers (aggregate)
3: Fiber web forming the filtration layer of the air discharge surface 4: Particle counter (upstream)
5: Filter material 6: Particle counter (downstream)
7: Manometer

Claims (4)

A polyphenylene sulfide fiber characterized in that the number of crimps is 10 to 15 peaks / 25 mm and the crimp frequency ratio satisfies the following formula (1).
Formula (1): −0.07 N + 2.1 ≦ Y ≦ −0.07 N + 2.3
N = number of crimps Y = number of crimp frequency ratio Here, N is the number of crimps, Y is the ratio of crimp frequency, and the ratio of crimp frequency is given by equation (2).
Formula (2): Y (crimping frequency ratio) = crimp degree (%) / crimp number (peak / 25 mm)   The polyphenylene sulfide fiber according to claim 1, wherein the strength is 4.0 to 5.5 cN / dtex.   The polyphenylene sulfide fiber according to 1 above, which has a single fiber fineness of 0.9 to 3.0 dtex. A fiber structure comprising 40% by mass or more of the polyphenylene sulfide fiber according to any one of claims 1 to 3.