JP4952141B2 - Fiber structure and bug filter comprising the same - Google Patents

Description

  The present invention relates to a fiber structure excellent in heat resistance used in a heat-resistant dust collecting device that separates solid and gas at high temperatures. In particular, the present invention relates to a heat-resistant bag filter for separating a large amount of dust from high-temperature gas, such as a coal boiler plant, a garbage incineration plant, a cement firing plant, and an asphalt production plant.

  Polyarylene sulfide fibers are widely used in the heat-resistant bag filter field as fibers excellent in heat resistance and chemical resistance. In addition, as disclosed in Patent Documents 1 to 4, it is also known that polyarylene sulfide fibers can be oxidized to obtain polyarylene sulfide oxide fibers, and that PPSO fibers can be used in heat-resistant bag filters. Polyarylene sulfide oxide fiber is a material with extremely high chemical resistance, especially when it is used as a bag filter for filtering dust from combustion gas, and it has higher acid resistance than meta-aramid fiber and polyimide fiber. When used in various liquid filtration filters, it exhibits excellent organic solvent resistance in addition to these chemical resistances. That is, it has the ability to maintain strength for a long time in these gas and liquid environments. It also surpasses meta-aramid fiber in heat resistance and has characteristics comparable to polyimide fiber.

When used in a polyarylene sulfide oxide fiber bag filter, it was not melted even by high-temperature dust, but partially reduced filtration performance due to heat shrinkage, that is, increased filtration pressure loss and reduced collection performance It was observed.
JP 63-182413 A JP-A-5-230760 JP-A-6-81270 JP 2006-16585 A

  In view of the problems of the background art, the present invention is intended to provide a bag filter cloth and a bag filter that satisfy all the characteristics required of a bug filter at a high level.

  That is, the fiber structure of the present invention is a bag filter that can prevent deterioration in filtration performance by reducing the heat shrinkage rate while maintaining the excellent heat resistance and chemical resistance of the polyarylene sulfide oxide fiber. A fiber structure suitable for use is provided.

  The present invention employs the following means in order to solve such problems.

That is, the fiber structure of the present invention includes a non-woven fabric mainly composed of polyarylene sulfide oxide fibers having a dry heat shrinkage rate at 300 ° C. of 2% or less and a single yarn fineness of 0.1 dtex or more and 10 dtex or less. 200 g / m ² or more and 1000 g / m ² or less, and the vertical average strength is 200 N / 50 mm or more and 2000 N / 50 mm or less. Moreover, the bag filter of this invention is comprised by this fiber structure, It is characterized by the above-mentioned.

  According to the present invention, as described above, since it is possible to provide a fiber structure that satisfies all the characteristics required for the bag filter at a high level, a coal boiler plant, a garbage incineration plant, a cement burning plant, and an asphalt manufacturing A filter cloth suitable for a dust collector used to separate a large amount of dust from a hot gas, such as a plant, can be provided.

In the present invention, polyarylene sulfide oxide is
General formula (1)

(R ″ represents hydrogen, halogen, an aliphatic substituent substituted with any functional group within an allowable range of valence, or an aliphatic substituent substituted with an aromatic substituent; R ″ may be linked to each other to form a crosslinked structure. R ″ may be a polymer chain made of polyarylene sulfide oxide. R ′ ″ is made of polyarylene sulfide oxide. Represents a polymer chain, m represents any of 0 to 3. X represents any of 0, 1, and 2. Of the repeating units represented by the general formula (1), X is 0, The ratio of the structural unit in which X is 1 or 2 in the structural units of 1 and 2 is 0.5 or more. ) The polymer consisting of the repeating unit represented by), or the above repeating as the main structural unit 1 unit per mole of repeating unit 0.0 mol or less, preferably 0.3 mol or less of the general formulas (2) to (8)

(R ″ represents any one of hydrogen, halogen, an aliphatic substituent substituted with an arbitrary functional group within an allowable range of valence, and an aliphatic substituent substituted with an aromatic substituent; `` '' Represents an aliphatic substituent substituted with an arbitrary functional group within an allowable range of valence, and R or R ′ between molecules may be linked to each other to form a crosslinked structure. R ″ and R ″ ″ may be a polymer chain composed of polyarylene sulfide oxide. R ′ ″ represents a polymer chain composed of polyarylene sulfide oxide, and m is any of 0-3. N represents any one of 0 to 2. X represents any one of 0, 1, and 2). Moreover, among the repeating units represented by the general formula (1), the ratio of the structural units in which X is 1 or 2 in the structural units in which X is 0, 1, or 2 needs to be 0.5 or more. There are, preferably 0.7 or more.

  The cross-linking generated in the oxidation reaction treatment process in the present invention means forming a bridge structure between polymer molecules in the process of oxidizing the polyarylene sulfide compound, and the carbon atom contained in the structure of the repeating unit, It means that atoms selected from either sulfur atoms or oxygen atoms combine to form a bridge structure. The degree of crosslinking can be confirmed by solid state NMR analysis of the polyarylene sulfide oxide fiber.

  The polyarylene sulfide oxide fiber in the present invention is a fiber composed of the polyarylene sulfide oxide. The length / thickness ratio of the fiber is 100 or more, and may be a long fiber. The thickness of the fiber needs to be not less than 0.1 dtex and not more than 10 dtex. If it is less than 0.1 dtex, the ventilation resistance when the fiber structure is formed becomes too high, and an efficient filter cannot be obtained. Further, when the single yarn fineness exceeds 10 dtex, the collection efficiency is lowered. For these purposes, the single yarn fineness is preferably 0.5 dtex or more and 8 dtex or less, more preferably 1 dtex or more and 6 dtex or less.

  The cross-sectional shape of the polyarylene sulfide oxide fiber is not particularly limited, and is not limited to a normal circular cross-section, but a Δ cross-section, a Y-shaped cross section, a □ cross-section, a cross-section, a hollow cross-section, a C-shaped cross section, a rice-shaped cross section, etc. Any irregular cross section can be adopted.

  The dry heat shrinkage rate at 300 ° C. of the polyarylene sulfide oxide fiber of the present invention is required to be 2% or less. When this value exceeds 2%, when used in a polyarylene sulfide oxide bag filter, high temperature dust may cause a decrease in filtration performance due to heat shrinkage, that is, an increase in filtration pressure loss and a decrease in collection performance. is there. In the present invention, in order to solve this problem, by adopting a novel manufacturing method as will be described later, it is possible to reduce the shape change due to contact with a high-temperature object, and it is suitable for a bag filter that can withstand long-term use. We have found a fiber structure from which one can be obtained.

  In addition, the polyarylene sulfide oxide fiber of the present invention preferably has a heat of fusion of 10 J / g or less in the measurement with a differential scanning calorimeter (DSC), and does not substantially have a melting peak. preferable. By lowering the heat of fusion to a level that cannot be confirmed in the limit, it is possible to prevent the fiber structure from being melted and deteriorated by contact with a high-temperature material, and to improve the durability of the filtration performance.

  The fiber structure of the present invention includes a nonwoven fabric composed of fibers having the single yarn fineness described above. If the nonwoven fabric is not included, the collection efficiency for collecting dust having a small particle diameter is lowered.

The fiber structure of the present invention has a basis weight of 200 g / m ² or more and 1000 g / m ² or less. When used as a bag filter, backwashing is performed to remove the collected dust. Backwashing is an operation in which a compressed air pulse is applied in the opposite direction to that during collection, and the collected dust is screened out. When the basis weight is less than 200 g / m ² , the dust collection volume becomes small, and frequent backwashing is performed, which shortens the filter life. On the other hand, if the weight per unit area exceeds 1000 g / m ² , the filter becomes unnecessarily heavy and the ventilation resistance increases, which is disadvantageous in terms of equipment cost.

  The vertical average strength of the fiber structure of the present invention is 200 N / 50 mm or more and 2000 N / 50 mm or less. In the case of less than 200 N / 50 mm, the fiber is deteriorated and the collection efficiency is deteriorated by an impact caused by backwashing or an impact caused by a collision with the retainer after the compressed air pulse injection. On the other hand, if the average vertical strength exceeds 2000 N / 50 mm, the filter becomes unnecessarily heavy and the ventilation resistance is increased, which is disadvantageous in terms of equipment cost.

The fiber structure of the present invention preferably has an apparent density of 0.25 g / cm ³ or more and 0.70 g / cm ³ or less. By setting the apparent density to 0.25 g / cm ³ or more, the durability against wear is improved and the collection efficiency is hardly lowered. Further, by setting the apparent density to 0.70 g / cm ³ or less, dust can be collected without requiring excessive ventilation resistance.

  As described above, the fiber structure of the present invention includes a non-woven fabric, but it may be composed of a non-woven fabric or a woven or knitted fabric. That is, a fiber structure for a bag filter or the like is required to have two characteristics, that is, improvement in collection efficiency and strength. In order to improve the collection efficiency, in the woven or knitted fabric, a large gap is formed in the weave or the stitch portion, and therefore a non-woven fabric is preferably used. However, in terms of strength, since the nonwoven fabric alone is somewhat small, it is preferable to combine a woven or knitted fabric if possible in terms of cost and design. The combination method of the woven / knitted fabric and the nonwoven fabric may be a three-layer structure of nonwoven fabric / woven / knitted fabric / nonwoven fabric, or may have a two-layer structure of nonwoven fabric / woven / knitted fabric. Such a production method is preferably a production method in which a nonwoven fabric and a woven or knitted fabric before fiber entanglement are laminated and the entanglement of the nonwoven fabric and the woven or knitted fabric are integrated by a needle punch or a water jet punch. . Thus, a high-strength fiber structure can be obtained by inserting a woven or knitted fabric into the polyarylene sulfide oxide fiber nonwoven fabric constituting the fiber structure. When combining woven or knitted fabrics, not only polyarylene sulfide oxide fibers but also woven or knitted fabrics made of fibers of other materials can be used. For example, fluorine fiber, glass fiber, silica fiber, carbon fiber and the like are preferably used. Fluorine fiber is an organic fiber, but is a fiber having extremely high heat resistance, and glass fiber, silica fiber, and carbon fiber are inorganic fibers and are also fibers having extremely high heat resistance. By using these highly heat-resistant fibers as a woven or knitted fabric, even when used as a plant bug filter exposed to higher temperatures, a bag filter that has higher heat resistance and is less likely to break even at high temperatures. Obtainable.

  The non-woven fabric of the present invention can be composed of 100% polyarylene sulfide oxide fiber, but is mixed with at least one different fiber selected from glass fiber, silica fiber, fluorine fiber, carbon fiber, and polyarylene sulfide fiber. It may be a non-woven fabric. That is, a bag filter cloth with improved mechanical strength such as abrasion can be provided by blending with these different fibers.

  Below, it describes about the manufacturing method of the fiber structure of this invention.

  As a method for obtaining the polyarylene sulfide oxide fiber, it can be obtained by oxidizing a fiber made of a polyarylene sulfide compound.

  The polyarylene sulfide compound referred to here is the following general formula (9)

(R represents at least one of hydrogen, halogen, an aliphatic substituent substituted with an arbitrary functional group within an allowable range of valence, and an aliphatic substituent substituted with an aromatic substituent. ) Or a repeating unit represented by formula (10) to (16) having a repeating unit of 1.0 or less, preferably 0.3 or less, per mole of the repeating unit. )

(R represents hydrogen, halogen, an aliphatic substituent substituted with an arbitrary functional group within an allowable range of valence, or an aliphatic substituent substituted with an aromatic substituent, and R ′ represents Represents an aliphatic substituent substituted with an arbitrary functional group within an allowable range of the valence.)).

  Among them, the substituents R and R ′ are preferably hydrogen or an aliphatic substituent having 1 to 4 carbon atoms. Specific examples thereof are hydrogen, methyl group, ethyl group, n-propyl group, iso-propyl group, and n-butyl group. , Iso-butyl group, and tert-butyl group. Among these, a methyl group, an ethyl group, an iso-propyl group, and a tert-butyl group are more preferable, and a methyl group is particularly preferable.

  Specific examples of such a polyarylene sulfide compound include poly-p-phenylene sulfide, poly-p-tolylene sulfide, poly-p-chlorophenylene sulfide, poly-p-fluorophenylene sulfide, and the like. , Poly-p-phenylene sulfide and poly-p-tolylene sulfide, more preferably poly-p-phenylene sulfide.

  The fiber composed of the polyarylene sulfide compound is obtained by melt spinning, stretching, and heat treatment of the polyarylene sulfide compound. The melt spinning is preferably performed at a spinning temperature of 290 to 350 ° C. and a spinning speed of 400 to 3000 m / min. Stretching and heat treatment may be performed subsequent to spinning, and after spinning, the film may be temporarily stored in a can or wound and then passed through a stretching heat treatment step. Stretching is performed in one or more stages at a draw ratio of 1.5 to 7 depending on the physical properties of the melt-spun fiber, and subsequently heat treated at a maximum temperature of 150 to 270 ° C. This polyarylene sulfide fiber preferably has a strength of 1.5 to 6 cN / dtex, a breaking elongation of 10 to 60%, and an elastic modulus of 20 to 70 cN / dtex. Moreover, it is preferable that the crystallinity is 30% or more and the weight average molecular weight is 30000 (Mw) or more, and the crystallinity is more preferably 50% or more. The weight average molecular weight is more preferably 40000 (Mw) or more. By using a polyarylene sulfide fiber having a crystallinity of 30% or more and a weight average molecular weight of 40,000 or more, the crystallinity and molecular weight of the polyarylene sulfide oxide produced as a result are not greatly impaired even in the oxidation reaction treatment. Gives good results in terms of physical properties.

The obtained polyarylene sulfide fiber is subjected to an oxidation reaction. The reaction liquid used for the oxidation reaction is a liquid in which water, acetic acid and sulfuric acid are mixed , and the mixed composition ratio is 5 to 20% by weight of water, 60 to 90% by weight of acetic acid, and 5 to 20% by weight of sulfuric acid. Is preferred. By setting it as such a reaction liquid and a composition ratio, the dry heat shrinkage rate in 300 degreeC can be reduced. Moreover, hydrogen peroxide is preferable as the oxidizing agent, and when hydrogen peroxide is present in the reaction liquid, equilibrium peracetic acid is generated in the liquid, and sulfuric acid is present to promote the oxidation of polyarylene sulfide fibers. To do. The concentration of hydrogen peroxide in the oxidation reaction liquid is preferably 0.1 to 10% by weight, more preferably 3 to 8% by weight. A good reaction result can be obtained at a concentration within this range, and a highly safe process can be constructed. In order to further improve the dry heat shrinkage and safety at 300 ° C., a method of sequentially adding sulfuric acid to the reaction solution is preferable.

Furthermore the reaction temperature is required to be 50 ° C. or less, preferably to be able to reduce the dry heat shrinkage at 300 ° C.. The reaction temperature is preferably at least 10 ° C. in order to short the reaction, good preferable at least 20 ° C..

  When polyarylene sulfide fibers are subjected to an oxidation reaction, two reactions occur simultaneously: a sulfonation reaction in which sulfide bonds proceed to sulfoxide bonds and sulfone bonds, and a crosslinking reaction in which arylene groups form a crosslinked structure. The polyarylene sulfide oxide fiber of the present invention is characterized by a low dry heat shrinkage rate at a high temperature of 300 ° C. or higher. For that purpose, the formation of a crosslinked structure is promoted and the polyarylene sulfide oxide molecule is It is necessary to suppress the thermal vibration of the chain. Surprisingly, the present invention does not use conventional peracetic acid or a high-temperature condition of 60 ° C. or higher for the generation of a crosslinked structure that originally requires high energy. It has been found that it is more effective to adopt mild oxidation reaction conditions. On the other hand, if it is too mild, the cross-linking reaction hardly progresses, and a sufficient cross-linking structure cannot be formed only with an inorganic salt peroxide such as sodium perborate as an oxidizing agent.

  Although the mechanism is not clear, under mild oxidation conditions such as the present invention, although the sulfonation reaction takes precedence in the early stage of the reaction, a crosslinked structure is not formed even after the sulfonation reaction is almost completed. Therefore, it seems that an efficient cross-linking reaction may occur because the molecular chain can be easily moved. Furthermore, it seems that the sulfone bond is more likely to radicalize the aryl group and the crosslinking reaction more easily than the sulfide bond.

  As long as such a phenomenon occurs and the object of the present invention can be achieved, the oxidation treatment liquid contains a small amount of any organic acid or organic acid anhydride, or a small amount of any inorganic salt peroxide as an oxidizing agent. Does not preclude inclusion.

  There is no particular limitation on the treatment method for performing the oxidation reaction treatment, but a batch type or continuous type, or a combination thereof can be adopted, and either a single-stage process or a multistage process can be adopted.

  Here, the batch type means that a fiber comprising a polyarylene sulfide compound and a liquid containing an oxidant are charged into an arbitrary reaction vessel and subjected to an oxidation reaction treatment at an arbitrary concentration, temperature, and time, and then polyarylene sulfide oxidation. This means a treatment method for taking out physical fibers or liquids, and the continuous type is an oxidation reaction treatment in which a fiber containing a polyarylene sulfide compound or a liquid containing an oxidizing agent is allowed to flow through a reaction vessel with an arbitrary flow rate. Means method. In the continuous type, a method of performing an oxidation reaction treatment by circulating or circulating a liquid containing an oxidant on a fiber composed of a polyarylene sulfide compound fixed in an arbitrary form, or a liquid containing an oxidant. Any method can be employed in which an oxidation reaction treatment is carried out by introducing into an arbitrary reaction vessel and continuously circulating or circulating fibers made of a polyarylene sulfide compound.

  Further, the multistage process means a process in which unit processes of oxidation reaction treatment adopting a batch type or a continuous type are constructed in a plurality or in stages. Specifically, the oxidation reaction treatment is divided into a plurality of times, and when each treatment is performed, a method of newly preparing a liquid containing an oxidizing agent for performing the oxidation reaction treatment and performing the subsequent oxidation reaction treatment is exemplified. . Such a method is preferable in that the oxidation reaction can be promoted. Specifically, it is preferably used in that the oxidation reaction treatment time can be shortened and the reaction can be performed at a lower temperature. In particular, the oxidation reaction treatment that can occur by diluting with a liquid so that it is sufficiently immersed or reducing the concentration to ensure safety, due to the influence of the form and apparent volume of fibers made of polyarylene sulfide compounds This multi-stage process is preferable because it can suppress the extension of time and eliminate the need for excessive temperature rise. By adopting this process, safety is ensured without incurring an extended oxidation reaction time or temperature rise. Process construction can be done above.

  After the oxidation treatment, it is desirable to perform a neutralization treatment or a water washing treatment.

  Furthermore, the method of contacting the fiber comprising the polyarylene sulfide compound with the liquid containing the oxidizing agent in the oxidation reaction treatment is a method of immersing the fiber comprising the polyarylene sulfide compound in the liquid containing the oxidizing agent, in any form. Any method of spraying or spraying a liquid containing an oxidant on a fiber comprising an immobilized polyarylene sulfide compound can be employed.

  The oxidation treatment can be performed in the state of the polyarylene sulfide fiber before the non-woven fabric is formed, or a fiber structure made of the polyarylene sulfide oxide fiber by oxidation after the non-woven fabric is formed.

  Whether it is a polyarylene sulfide fiber or a polyarylene sulfide oxide fiber, a nonwoven fabric can be produced by carding short fibers with crimps to divide the fibers and align the fibers in the same direction. Can be laminated into a web, and the web can be entangled or integrated into a nonwoven fabric. As the entanglement method, a needle punch method in which the needle is entangled by hitting a needle, a water jet punch production method in which the water stream is entangled and the like are preferably used. Alternatively, as an integration method, a method of partially pressing and consolidating with a hot press or a hot embossing press may be used. In this method by hot pressing or hot embossing, a method in which a small amount of fibers to be heat-softened is mixed in advance is also preferably used. Specific examples of the fiber to be mixed include polytetrafluoroethylene fiber, polyarylene sulfide fiber, meta-aramid fiber, and the like.

  The bag filter of the present invention is preferably obtained by sewing the fiber structure composed of the polyarylene sulfide oxide fiber described above, but after obtaining the bag filter sewn the fiber structure composed of the polyarylene sulfide fiber, An oxidation treatment method can also be employed. As a sewing method, literal sewing using a sewing thread is preferable. However, it is necessary to use a sewing thread that is careful and has good heat resistance, such as a sewing thread made of m-aramid fiber, a sewing thread made of polyarylene sulfide fiber, a sewing thread made of polyimide fiber, etc. However, a sewing thread made of polyarylene sulfide oxide fiber or a sewing thread made of polytetrafluoroethylene fiber is preferably used.

  In addition, as a sewing method in the case where no sewing thread is used, melt sewing using ultrasonic waves, electrical high frequencies, or a hot plate, a so-called welder is also preferably used. However, when welder sewing is performed, it is needless to say that polyarylene sulfide oxide fibers do not have a melting point, and therefore, it is necessary to devise such as blending fibers having a melting point.

  Hereinafter, the present invention will be specifically described with reference to Examples. In the examples and comparative examples, polyarylene sulfide oxide fibers are abbreviated as PPSO fibers, and polyarylene sulfide fibers are abbreviated as PPS fibers.

[Measuring method]
(1) Differential scanning calorific value (DSC) (heat of fusion)
Using a differential scanning calorimeter (RDC220 (Seiko Instruments)), under a nitrogen atmosphere, with a nitrogen flow rate of 20 mL / min, a sample amount of 5 mg obtained by extracting fibers from the nonwoven fabric was weighed, and a temperature program: 10 from 30 ° C. to 340 ° C. DSC when the temperature is raised at ℃ / minute, held for 2 minutes, lowered from 340 ℃ to 30 ℃ at 10 ℃ / minute, held for 2 minutes, and then heated from 30 ℃ to 500 ℃ at 10 ℃ / minute From the curve, the heat of fusion was measured.

(2) Dry heat shrinkage rate at 300 ° C. According to JIS L 1015: 1992, a sample with a grip distance of 25 mm was prepared, suspended in a dryer at 300 ° C. for 30 minutes, and the dry heat shrinkage rate was determined. Was 30 times, and the average value was determined.

(3) Basis weight Based on JIS L 1906: 2000 5.2, three 20 cm × 25 cm test pieces were taken per 1 m width of the sample, each mass (g) in the standard state was measured, and the average value was 1 m. Expressed in mass per ² (g / m ² ).

(4) Apparent density of non-woven fabric (non-woven fabric thickness)
Consistent with JIS L 1906: 2000, applied to JIS L 1906: 2000, 10 thicknesses per 1 m width of the sample, using a thickness measuring machine, the thickness is reduced under a pressure of 2 kPa with a 22 mm diameter pressurizer. Then, after waiting for 10 seconds, the thickness was measured and the average value was calculated.

(Apparent density)
From the basis weight and thickness obtained above, the apparent density (g / cm ³ ) was determined by the following formula.
A _g = S _m / (1000 × t)
Here, A _g : Apparent density (g / cm ³ )
S _m : basis weight (g / m ² )
t: Thickness (mm)
(5) Vertical average strength 5cm width and 30cm length samples are prepared, the test piece width is 50mm, the distance between chucks is 200mm, and the tensile speed is 200mm / min. It was.

Example 1
Spinning temperature of 330 ° C. PPS (polymer having general formula (9) with R = H as basic skeleton) having an apparent viscosity of 370 Pa · s at 300 ° C. , Melt-spinning at a take-up speed of 450 m / min, 4.0 times stretching using a heating roll at 90 ° C., heat treatment using a hot plate at 200 ° C. to obtain a fiber with 84 dtex 24 filaments (single yarn fineness 3.5 dtex), Two hundred yarns of this fiber were combined to give indentation crimps and cut to a fiber length of 51 mm to obtain PPS raw cotton. This raw cotton is made into a non-woven fabric having a basis weight of 500 g / m ² and an apparent density of 0.45 g / cm ³ through a card, a cross wrapper and a needle punch, and a non-woven fabric having a width of 60 cm. ) And 34.5% hydrogen peroxide solution 7.4 kg (manufactured by Kanto Chemical Co., Inc.) and heated to 40 ° C., followed by 2% of 95% sulfuric acid (manufactured by Kanto Chemical Co., Ltd.) over 30 minutes. The whole amount was dropped, and then the reaction was carried out for about 2 hours to obtain a PPSO fiber structure. The PPSO fiber constituting the fiber structure has a single yarn fineness of 4.6 dtex, a dry heat shrinkage at 300 ° C. of 1.5%, and does not have a melting point in the DSC measurement. The polymer was presumed to have R ″ = H, m = 0 as a basic skeleton, and partially m = 1 (that is, having a crosslinked structure). Further, this fiber structure had a basis weight of 650 g / m ² , a vertical average strength of 1120 N / 50 mm, and an apparent density of 0.45 g / cm ³ . Moreover, when this fiber structure was used as a bug filter for a coal boiler, there was no change in the shape of the nonwoven fabric surface after 6 months of use, and there was no problem in pressure loss and collection efficiency.

Comparative Example 1
In Example 1, an acetic acid solution of peracetic acid (9% concentration) was used as the oxidizing solution and treated at 30 ° C. for 2 weeks. The PPSO fiber constituting the fiber structure has a single yarn fineness of 4.3 dtex, a dry heat shrinkage at 300 ° C. of 2.8%, and has no melting point in DSC measurement. It was 620 g / m ² , vertical average strength 1110 N / 50 mm, and apparent density 0.43 g / cm ³ . In addition, when this fiber structure was used as a bug filter for a coal boiler, after 6 months of use, the surface of the nonwoven fabric had mottled shrinkage, which caused a slight decrease in pressure loss and a decrease in collection efficiency. It was.

Example 2
A fiber structure composed of PPSO fibers was obtained in the same manner as in Example 1 except that the spinning temperature was 310 ° C., the spinning speed was 4500 m / min, and the fibers were 67 dtex 24 filaments (single yarn fineness 2.5 dtex). The PPSO fiber constituting the fiber structure has a single yarn fineness of 4.6 dtex, a dry heat shrinkage at 300 ° C. of 1.7%, and has no melting point in DSC measurement. It was 650 g / m ² , vertical average strength 850 N / 50 mm, and apparent density 0.45 g / cm ³ . Moreover, when this fiber structure was used as a bug filter for a coal boiler, there was no change in the shape of the nonwoven fabric surface after 6 months of use, and there was no problem in pressure loss and collection efficiency.

Comparative Example 2
In Example 2, an acetic acid solution of peracetic acid (20% concentration) was used as the oxidizing solution, and a fiber structure composed of PPSO fibers was obtained in the same manner as in Example 2 except that the treatment was performed at 40 ° C. for 1 hour. The PPSO fiber constituting the fiber structure has a single yarn fineness of 4.2 dtex, a dry heat shrinkage of 2.9% at 300 ° C., and has no melting point in the DSC measurement. It was 620 g / m ² , vertical average strength 870 N / 50 mm, and apparent density 0.43 g / cm ³ . In addition, when this fiber structure was used as a bug filter for a coal boiler, after 6 months of use, the surface of the nonwoven fabric had mottled shrinkage, which caused a slight decrease in pressure loss and a decrease in collection efficiency. It was.

Example 3
A fiber structure composed of PPSO fibers was obtained in the same manner as in Example 1 except that Torucon's “Torcon” 2.2 dtex × 51 mm PPS raw cotton was used. The PPSO fiber constituting the fiber structure has a single yarn fineness of 3.0 dtex, a dry heat shrinkage at 300 ° C. of 1.4%, and has no melting point in DSC measurement. It was 660 g / m ² , vertical average strength 1090 N / 50 mm, and apparent density 0.45 g / cm ³ . Moreover, when this fiber structure was used as a bug filter for a coal boiler, there was no change in the shape of the nonwoven fabric surface after 6 months of use, and there was no problem in pressure loss and collection efficiency.

Comparative Example 3
A fiber structure made of PPSO fibers was obtained in the same manner as in Example 3 except that the oxidation conditions were 60 ° C. The PPSO fiber constituting the fiber structure has a single yarn fineness of 3.0 dtex, a dry heat shrinkage of 2.5% at 300 ° C., and has no melting point in DSC measurement. It was 670 g / m ² , vertical average strength 1230 N / 50 mm, and apparent density 0.43 g / cm ³ . In addition, when this fiber structure was used as a bug filter for a coal boiler, after 6 months of use, the surface of the nonwoven fabric had mottled shrinkage, which caused a slight decrease in pressure loss and a decrease in collection efficiency. It was.

Example 4
4 kg of PPS raw cotton of Example 3 was immersed in the oxidizing liquid of Example 1 maintained at 40 ° C., and then 2 kg of 95% sulfuric acid (manufactured by Kanto Chemical Co., Inc.) was dropped over 30 minutes, and then about 2 Time reaction was performed to obtain PPSO fiber. This raw cotton was subjected to a card, a cross wrapper, and a needle punch to obtain a fiber structure made of a PPSO nonwoven fabric having a basis weight of 650 g / m ² and an apparent density of 0.45 g / cm ^{3 and} a width of 60 cm. The PPSO fiber constituting the fiber structure has a single yarn fineness of 3.0 dtex, a dry heat shrinkage rate at 300 ° C. of 1.5%, and has no melting point in the DSC measurement. The vertical horizontal average strength was 1060 N / 50 mm, and the apparent density was 0.45 g / cm ³ . Moreover, when this fiber structure was used as a bug filter for a coal boiler, there was no change in the shape of the nonwoven fabric surface after 6 months of use, and there was no problem in pressure loss and collection efficiency.

Comparative Example 4
A fiber structure made of PPSO fibers was obtained in the same manner as in Example 4 except that the oxidation conditions were 60 ° C. The single yarn fineness is 3.0 dtex, the dry heat shrinkage at 300 ° C. is 2.5%, and it has no melting point in the DSC measurement. The fiber structure has a basis weight of 650 g / m ² , and a vertical average strength of 1040 N / 50 mm. The apparent density was 0.45 g / cm ³ . In addition, when this fiber structure was used as a bug filter for a coal boiler, after 6 months of use, the surface of the nonwoven fabric had mottled shrinkage, which caused a slight decrease in pressure loss and a decrease in collection efficiency. It was.

Example 5
A fiber structure composed of PPSO fibers was obtained in the same manner as in Example 3 except that “Torcon” 1.0 dtex-51 mm was used as PPS raw cotton, the temperature of the oxidation reaction was 30 ° C., and the time was 1 hour. The PPSO fiber constituting the fiber structure has a single yarn fineness of 1.3 dtex, a dry heat shrinkage at 300 ° C. of 1.6%, and has no melting point in DSC measurement. It was 670 g / m ² , vertical average strength 1020 N / 50 mm, and apparent density 0.45 g / cm ³ . Moreover, when this fiber structure was used as a bug filter for a coal boiler, there was no change in the shape of the nonwoven fabric surface after 6 months of use, and there was no problem in pressure loss and collection efficiency.

Example 6
Using the PPS raw cotton of Example 4, a 20th PPSO spun yarn was obtained through each step of card, sliver, roving and fine spinning in accordance with a normal method. Using the obtained PPSO spun yarn, a plain weave PPSO woven fabric having a coarse basis weight of 130 g / m ² was obtained through a normal woven fabric process. Furthermore, two PPSO nonwoven fabrics having a basis weight of about 200 g / m ^{2 and} having a basis weight of about 200 g / m ² were obtained using the PPSO raw cotton obtained in Example 4. Using these, three layers were laminated in the order of PPSO non-woven fabric / PPSO woven fabric / PPSO non-woven fabric to obtain a needle punching step, thereby obtaining a non-woven fabric having a basis weight of 530 g / m ² and an apparent density of 0.40 g / cm ³ . The PPSO fiber constituting the nonwoven fabric of this fiber structure has a single yarn fineness of 3.0 dtex, a dry heat shrinkage at 300 ° C. of 1.5%, and has no melting point in the DSC measurement. The vertical average strength was 970 N / 50 mm, and the apparent density was 0.49 g / cm ³ . Moreover, when this fiber structure was used as a bug filter for a coal boiler, there was no change in the shape of the nonwoven fabric surface after 6 months of use, and there was no problem in pressure loss and collection efficiency.

Comparative Example 5
A PPSO fiber structure was obtained in the same manner as in Example 3 except that the fiber structure had a basis weight of 150 g / m ² and an apparent density of 0.45 g / cm ³ . The PPSO fiber constituting the present fiber structure has a single yarn fineness of 3.0 dtex, a dry heat shrinkage at 300 ° C. of 1.4%, and does not have a melting point in the DSC measurement. The vertical average strength was 210 N / 50 mm. When this fiber structure was used as a bag filter for a coal boiler, the wear was large around the retainer contact portion.

Example 7
A PPSO fiber structure was obtained in the same manner as in Example 3 except that the fiber structure had a basis weight of 660 g / m ² and an apparent density of 0.20 g / cm ³ . The PPSO fiber constituting the present fiber structure has a single yarn fineness of 3.0 dtex, a dry heat shrinkage at 300 ° C. of 1.4%, and does not have a melting point in the DSC measurement. The average vertical strength was 560 N / 50 mm. When this fiber structure was used as a bug filter for a coal boiler, only injuries were seen only at the retainer contact portion, and the abrasion resistance was slightly inferior to Example 3.

Example 8
A PPSO fiber structure was obtained in the same manner as in Example 3 except that the oxidation condition was 20 ° C. and the treatment time after dropping sulfuric acid was 24 hours. The PPSO fiber constituting the fiber structure has a single yarn fineness of 3.0 dtex, a dry heat shrinkage rate at 300 ° C. of 1.3%, and has no melting point in DSC measurement. It was 660 g / m ² , vertical average strength 1140 N / 50 mm, and apparent density 0.44 g / cm ³ . Moreover, when this fiber structure was used as a bug filter for a coal boiler, there was no change in the shape of the nonwoven fabric surface after 6 months of use, and there was no problem in pressure loss and collection efficiency.

Claims (5)

A fiber obtained by oxidizing polyarylene sulfide fibers in a liquid in which water, acetic acid and sulfuric acid are mixed at a temperature of 10 ° C. or higher and 50 ° C. or lower, and a dry heat shrinkage rate at 300 ° C. of 2% or lower. And a non-woven fabric mainly composed of polyarylene sulfide oxide fibers having a single yarn fineness of 0.1 dtex or more and 10 dtex or less, having a basis weight of 200 g / m ² or more and 1000 g / m ² or less, a vertical average strength of 200 N / 50 mm or more, The fiber structure characterized by being 2000 N / 50 mm or less. 2. The fiber structure according to claim 1, wherein the apparent density is 0.25 g / cm ³ or more and 0.70 g / cm ³ or less. The fiber structure according to claim 1 or 2, wherein the polyarylene sulfide oxide fiber is composed of a polymer composed of a repeating unit represented by the following general formula (1).

(R ″ represents hydrogen, halogen, an aliphatic substituent substituted with any functional group within an allowable range of valence, or an aliphatic substituent substituted with an aromatic substituent; R ″ may be linked to each other to form a crosslinked structure. R ″ may be a polymer chain made of polyarylene sulfide oxide. R ′ ″ is made of polyarylene sulfide oxide. Represents a polymer chain, m represents any of 0 to 3. X represents any of 0, 1, and 2. Of the repeating units represented by the general formula (1), X is 0, The proportion of structural units in which X is 1 or 2 in the structural units 1 and 2 is 0.5 or more. The fiber structure according to any one of claims 1 to 3, wherein the polyarylene sulfide oxide fiber has substantially no melting peak as measured by a differential scanning calorimeter (DSC).   It is comprised with the fiber structure of any one of Claims 1-4, The bag filter characterized by the above-mentioned.