Polyphenylene sulfide fibers and articles thereof

Abstract

The invention relates to a polyphenylene sulfide fiber with a crimped structure and a product thereof, the polyphenylene sulfide fiber is formed by compounding at least two polyphenylene sulfide materials, the composition and / or structure of the fiber are / is substantially consistent along the long axis direction of the fiber, and on any cross section of the fiber, the crimped structure of the fiber is larger than the crimped structure of the fiber. A central area and at least two edge areas which are not physically connected exist, the central area extends to at least part of the edge of the section, and the central area covers the central point of the equivalent circle of the section; each edge area extends to at least part of the edge of the section and does not cover the central point, the central area comprises polyphenylene sulfide A, the edge areas comprise polyphenylene sulfide B, the polyphenylene sulfide A is different from the polyphenylene sulfide B, the crystallization temperature of the polyphenylene sulfide A is lower than that of the polyphenylene sulfide B, and the crystallization temperature of the polyphenylene sulfide B is lower than that of the polyphenylene sulfide B. And the polyphenylene sulfide B structure contains a polar end group.

Description

Technical Field

[0001] This invention belongs to the field of materials, specifically relating to a polyphenylene sulfide fiber and its products, and more particularly, to a polyphenylene sulfide fiber with excellent crimp characteristics. Background Technology

[0002] Polyphenylene sulfide (PPS) fiber is a new type of special plastic fiber. PPS fiber has excellent thermal stability, flame retardancy, chemical resistance and excellent textile processability. Therefore, it is widely used in the production of needle-punched nonwoven fabrics and yarns. PPS fiber needle-punched nonwoven fabrics or woven fabrics can be used for filtering hot corrosive reagents and are ideal heat-resistant and corrosion-resistant materials.

[0003] The needle-punching process of PPS fibers generally involves carding, web laying, and needle punching to form the basic nonwoven fabric. However, the spinning process is more complex, including carding, drawing, sliver lap, combing, roving, and spinning. Therefore, the spinning process has higher requirements for the spinnability of fibers.

[0004] Furthermore, filter bags based on polyphenylene sulfide fibers are widely used in exhaust filtration for coal-fired boilers, waste incineration, and other applications. As national emission standards become increasingly stringent, the widely adopted technology to improve the dust removal efficiency of filter media is the processing of ultra-fine denier polyphenylene sulfide short fibers into non-woven fabrics.

[0005] For example, in reference 1, ultrafine polyphenylene sulfide short fibers with a diameter of 8~11μm and conventional polyphenylene sulfide short fibers with a diameter of 11.5~15μm are blended to reduce the pore size of the nonwoven fabric, thereby improving the dust removal efficiency; reference 2 uses a meltblown 2-10μm ultrafine polyphenylene sulfide fiber web layer to improve the filtration efficiency of the composite fiber filter material.

[0006] In addition, there are methods to adjust the pore size of nonwoven fabrics using needle punching equipment. For example, reference 3 provides a needle punching device for nonwoven fabrics with adjustable pore size.

[0007] Nonwoven fabrics made from conventional polyphenylene sulfide (PPS) fibers have large pore sizes, resulting in dust particle filtration efficiency that cannot meet stringent emission requirements. Using small-diameter ultrafine PPS fibers can reduce pore size and improve filtration efficiency, but ultrafine fibers are expensive, difficult to open and disperse, and challenging to process.

[0008] The ability of needle punching equipment to adjust the pore size of nonwoven fabrics is very limited, and the adjustment range of pore size generally cannot effectively improve filtration efficiency.

[0009] Therefore, there is still room for further improvement in the preparation of nonwoven bags based on polyphenylene sulfide fibers.

[0010] References:

[0011] Reference 1: CN114130121A

[0012] Reference 2: CN102512881B

[0013] Reference 3: CN222574962U Summary of the Invention

[0014] The problem the invention aims to solve

[0015] After existing polyphenylene sulfide short fibers are processed into nonwoven fabrics through carding, web laying, needle punching, and other processes, their "serrated" crimp characteristics will basically disappear under the influence of external forces such as stretching, compression, and impact, and the fibers will exhibit a similar appearance to... Figure 1 As shown in the straight line 'a', the pores formed between such fibers are relatively large, meaning the overall pore size of the nonwoven fabric is relatively large.

[0016] The applicant discovered that if fibers retain similar attachments in nonwoven fabrics Figure 1 In the crimped state shown in b, the pores between fibers become smaller, and with increasing crimp, the pores become even smaller and more uniform, resulting in a significant reduction in the average and maximum pore size of the nonwoven fabric. Therefore, the applicant believes that maintaining good crimp and crimp recovery rate of the fibers is important, as these properties can be imparted during nonwoven fabric processing to resist the reduction in crimp caused by processing techniques.

[0017] Furthermore, the applicant discovered that by adjusting the structure of polyphenylene sulfide fibers, especially their cross-sectional structure, and by using specific types of polyphenylene sulfide resins, the crimp and crimp recovery rate (creep elasticity and retention of that elasticity) of the fibers can be increased, thereby enabling the production of (needle-punched) nonwoven fabrics with better fiber crimp and better porosity.

[0018] Furthermore, based on this nonwoven fabric, filter bags and filter devices with further improved high-temperature filtration efficiency are provided.

[0019] Solution for solving the problem

[0020] It has been found that the above-mentioned technical problems can be solved by implementing the following technical solutions:

[0021] [1]. A polyphenylene sulfide fiber having a crimped structure, wherein the polyphenylene sulfide fiber is formed by compounding at least two polyphenylene sulfide resins, and the composition and / or structure of the fiber are substantially consistent along the fiber axial direction.

[0022] In any cross-section of the fiber, there exists a central region and at least two non-physically connected edge regions. The central region extends to at least a portion of the edge of the cross-section and covers the center point of the equivalent circle of the cross-section. Each edge region extends to at least a portion of the edge of the cross-section but does not cover the center point.

[0023] The central region includes polyphenylene sulfide A, the edge region includes polyphenylene sulfide B, and polyphenylene sulfide A is different from polyphenylene sulfide B.

[0024] Of the total area of ​​the cross-section, the area of ​​the central region is more than 50%.

[0025] The crystallization temperature of polyphenylene sulfide A is lower than that of polyphenylene sulfide B, and polyphenylene sulfide B contains polar end groups in its structure.

[0026] [2]. The fiber according to [1], wherein the fineness of the fiber is less than 2.8 dtex; the fiber is substantially a circular cross-section fiber.

[0027] [3]. The fiber according to [1] or [2], wherein the central region extends to at least two unconnected edges of the cross section; the edges extending from the central region account for less than 80% of the total length of the edges of the cross section.

[0028] [4]. The fiber according to any one of [1] to [3], wherein the shape of the central region in the cross section is rotationally symmetric about the axial direction of the fiber.

[0029] [5]. The fiber according to any one of [1] to [4], wherein the central region has at least one axis of symmetry passing through a neutral point on the cross section, and optionally, the central region has a gradient-varying width in a plane direction orthogonal to the axis of symmetry.

[0030] [6]. The fiber according to any one of [1] to [5], wherein the cross section has 2 to 5 edge regions, optionally, the overall shape formed by the edge regions has axisymmetry about the axial direction of the fiber.

[0031] [7]. The fiber according to any one of [1] to [6], wherein each edge region uses the same or different polyphenylene sulfide B independently.

[0032] [8]. The fiber according to any one of [1] to [7], wherein the crystallization temperature of the polyphenylene sulfide A is below 200°C and the crystallization temperature of the polyphenylene sulfide B is above 220°C.

[0033] [9]. The fiber according to any one of [1] to [8], wherein the polar end group of the polyphenylene sulfide B includes one or more of thiol, carboxyl, hydroxyl or sulfonic acid groups.

[0034]

[10] . The fiber according to any one of [1] to [9], wherein the fiber has one or more of the following properties:

[0035] i. The number of fiber crimps is 10~20 / 25mm;

[0036] ii. The fiber fineness is 0.7~2.8 dtex;

[0037] iii. The average crimp angle of the fiber after being held under a tensile stress of 0.1 cN / dtex for 10 min is 50~90° / cm;

[0038] iv. The fiber strength is above 4.0 cN / dtex.

[0039]

[11] . Furthermore, the present invention also provides a nonwoven fabric, wherein the nonwoven fabric comprises fibers according to any one of [1] to

[10] .

[0040]

[12] . The nonwoven fabric according to

[11] , wherein the nonwoven fabric is a needle-punched nonwoven fabric.

[0041]

[13] . The nonwoven fabric according to

[11] or

[12] , wherein the nonwoven fabric has one or more of the following characteristics:

[0042] a. The nonwoven fabric has a density of 100~200 g / m³. 2 The weight;

[0043] b. The number of crimps of the fibers in the nonwoven fabric is 6 to 16 per 25 mm;

[0044] c. The average pore size of the nonwoven fabric is less than 7 μm.

[0045]

[14] . In addition, the present invention also provides a filter bag, wherein the filter bag comprises or uses a nonwoven fabric according to any one of

[11] to

[13] .

[0046]

[15] . In addition, the present invention also provides a flue gas filtration device, wherein the device includes a filter bag according to

[14] , and the flue gas originates from the emissions of a combustion device.

[0047] The effects of the invention

[0048] By implementing the above technical solution, the present invention can achieve the following technical effects:

[0049] 1) By reconfiguring the structure and materials of polyphenylene sulfide fibers, the present invention can improve the crimping characteristics and the retention of crimping characteristics of the obtained fibers.

[0050] 2) Polyphenylene sulfide fibers with improved crimp properties can overcome the reduction of fiber crimp properties caused by processing technology in the preparation of nonwoven fabrics.

[0051] 3) Nonwoven fabrics using the polyphenylene sulfide fiber of the present invention can obtain nonwoven fabrics with smaller pore size. On the one hand, it is not necessary to reduce the fineness of the fiber of the present invention, and on the other hand, it is not necessary to use other ultrafine fibers. Therefore, it can also reduce process costs and opening difficulty.

[0052] 4) Since the fibers of the present invention can effectively reduce the pore size of nonwoven fabrics, the nonwoven fabrics can be set to a lower basis weight to save costs.

[0053] 5) The filter bag prepared from the nonwoven fabric according to the present invention can maintain excellent hot flue gas filtration efficiency. Attached Figure Description

[0054] Figure 1 The shape of nonwoven fabrics with different fiber properties

[0055] Figure 2 This invention relates to two typical cross-sectional morphologies of polyphenylene sulfide fibers.

[0056] Figure 3 Schematic diagram of the average curl angle measurement of this invention

[0057] Figure 4 The spinneret shape used in the example section

[0058] Figure 5 The crimping machine used in the examples section has the following parameters: Fs - force applied to the crimping roller; Fn - force applied to the crimping side blade; l - distance between the crimping roller and the crimping side blade; L - width of the crimping roller; d - gap between the crimping rollers. Detailed Implementation

[0059] The present invention will now be described in detail. The descriptions of the technical features described below are based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0060] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0061] Unless otherwise stated, in this instruction manual, "more" in "multiple", "multi-variety", "multiple", etc., means a value of 2 or more.

[0062] In this specification, the terms "substantially" or "truly" mean that the error compared to the relevant perfect or theoretical standard is less than 1%, or less than 0.8%, or less than 0.6%. Furthermore, when "all" or "entire" is used in this specification, it also means "all" or "entire" in the sense of "substantially" or "truly".

[0063] Unless otherwise specified, "%" in this instruction manual refers to the percentage content by mass.

[0064] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0065] In this specification, "optional" or "optionally" means that the event or situation described below may or may not occur, or may occur in any of the circumstances described, and the description includes both the occurrence and non-occurrence of the event.

[0066] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0067] In this specification, the terms “comprising” and / or “including” are used to indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0068] In this instruction manual, "normal temperature" or "room temperature" refers to an indoor ambient temperature of "23±2℃".

[0069] The present invention provides a polyphenylene sulfide fiber with an improved structural and material design, which has good crimping properties and crimping property retention. Furthermore, the present invention also provides a nonwoven fabric based on the fiber and a flue gas filter bag made using the nonwoven fabric.

[0070] This invention is mainly based on the following concept:

[0071] The applicant has discovered that nonwoven fabrics made from fibers with good crimp properties have reduced pore sizes, thereby avoiding the use of expensive and poorly processable microfibers. However, the crimp properties of conventional crimped fibers tend to weaken during nonwoven fabric processing. Therefore, this invention redesigns the fiber material and structure by incorporating different types of polyphenylene sulfide (PPS) resins in the central and edge regions. The PPS in the central region has a lower crystallization temperature than that in the edge region, and the PPS in the edge region contains polar end groups. Thus, the central region provides the primary mechanical properties, while the PPS in the edge region crystallizes more easily, and the polar end groups provide groups for forming hydrogen bonds, thereby generating bonding forces between different fibers. After the fiber crimp is formed, this bonding force acts as a "weld," thus better maintaining the formed crimp. Therefore, even after processing such as needle punching, nonwoven fabric products with good fiber crimp characteristics can be obtained.

[0072] <First Aspect>

[0073] In a first aspect, the present invention provides a polyphenylene sulfide fiber with an improved material and structure and a crimped structure. The polyphenylene sulfide fiber of the present invention is obtained based on two or more polyphenylene sulfide resins (and processed by fiber forming or spinning), and these fibers respectively form specific fiber structure regions.

[0074] Polyphenylene sulfide resin

[0075] In principle, there are no particular limitations on the source and synthesis method of the polyphenylene sulfide resin of the present invention, and various raw materials and synthesis routes in the art can be used to obtain the polyphenylene sulfide resin.

[0076] For example, the polyphenylene sulfide resin of the present invention is mainly formed of a polymer containing repeating units as follows:

[0077]

[0078] For the polyphenylene sulfide resin of the present invention, the content of the above-mentioned structural units is typically 80.0% by mass or more, preferably 90.0% by mass or more. Optionally, in addition to the above-mentioned structural units, the polyphenylene sulfide resin suitable for the present invention may also have other forms of aromatic sulfide units.

[0079] In some specific embodiments, the polyphenylene sulfide resin may be obtained by polymerizing sodium sulfide and p-dichlorobenzene in an organic solvent.

[0080] In addition, other components can be used in the synthesis according to the needs of molecular design, such as chain extenders and end-capping agents.

[0081] Different types or varieties of polyphenylene sulfide resins can be obtained by further adjusting the synthesis process.

[0082] In some specific embodiments, the weight-average molecular weight of the polyphenylene sulfide resin used in this invention can be 30,000 to 90,000, preferably 40,000 to 70,000. Specific examples include 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 80,000, and 85,000. Within the above molecular weight range, both mechanical strength and spinnability are considered. Furthermore, the polyphenylene sulfide resin of this invention preferably has a narrow molecular weight distribution characteristic; that is, the molecular weight distribution index of the polyphenylene sulfide resin of this invention can be below 3.8, preferably 2.7 to 3.6. By controlling the weight-average molecular weight and molecular weight distribution index of the polyphenylene sulfide resin used in spinning, and selecting a polyphenylene sulfide resin with a low distribution width, it is more conducive to the rapid orientation and crystallization of polyphenylene sulfide fibers during the drawing process, improving fiber density and thus achieving the purpose of improving initial mechanical strength.

[0083] For the polyphenylene sulfide resin used in this invention, two or more types can be used. Among them, polyphenylene sulfide A is the component that forms the central part of the fiber, polyphenylene sulfide B is the component that forms the edge part, and polyphenylene sulfide B can be one or more (B1, B2, B3...Bn, etc.).

[0084] For polyphenylene sulfide A, it provides the main mechanical properties of polyphenylene sulfide fiber. In some specific embodiments, it can have a melt crystallization temperature of 175°C or higher (hereinafter referred to as "crystallization temperature"). Preferably, the crystallization temperature can also be 180°C to 200°C, such as 185°C, 190°C, etc.

[0085] Polyphenylene sulfide B provides good retention of the crimp of polyphenylene sulfide fibers. Polyphenylene sulfide B also has a higher crystallization temperature compared to polyphenylene sulfide A. In some preferred embodiments, the polyphenylene sulfide B has a crystallization temperature of 220°C or higher, more preferably 225-260°C, including, but not limited to, 230°C, 235°C, 240°C, 245°C, 250°C, and 255°C.

[0086] Meanwhile, for polyphenylene sulfide B, its molecular ends have polar groups, especially polar groups with active hydrogen atoms. Further examples of polar groups include one or more of thiol, hydroxyl, carboxyl, or sulfonic acid groups. From the perspective of fiber thermal stability, durability, and crimp retention, the terminal group is preferably hydroxyl or carboxyl, and more preferably carboxyl. Such terminal groups can be obtained by adjusting the raw materials, chain extenders, and end-capping agents used in polycondensation, or by hydrolyzing the polymer.

[0087] In addition, considering both thermal stability and processability, for polyphenylene sulfide B, preferably, the content of sulfur end groups can be 1400~2000 mg / kg, more preferably 1500~1800 mg / kg.

[0088] Furthermore, the fibers of the present invention can be composed of the aforementioned polyphenylene sulfide resin A and polyphenylene sulfide resin B, as well as optional additives or auxiliaries. In some specific embodiments, the content of polyphenylene sulfide resin A, based on the total mass of the formed fibers, is 50% by mass or more, preferably 60-80% by mass, for example 65% by mass, 70% by mass, or 85% by mass; and the total content of polyphenylene sulfide B is less than 50% by mass, preferably 10-40% by mass, more preferably 15-30% by mass, for example 20% by mass, 25% by mass, etc.

[0089] Polyphenylene sulfide fiber structure

[0090] The polyphenylene sulfide fiber of the present invention is formed from the above-mentioned polyphenylene sulfide A and polyphenylene sulfide B, wherein the fiber is substantially consistent in composition and / or structure along the axial direction of the fiber of the present invention.

[0091] Therefore, it can be described from any cross-section of the fiber.

[0092] Specifically, in any cross-section of the polyphenylene sulfide fiber of the present invention, there are a central region and edge regions, the central region extending to at least a portion of the edge of the cross-section and covering the center point of the equivalent circle of the cross-section; each of the edge regions extends to at least a portion of the edge of the cross-section and does not cover the center point. In some specific embodiments, the fiber may have a substantially circular cross-section. Preferably, the boundary between the central region and the edge regions is typically a (smooth) curve without sharp corners (when viewed at 160x magnification in cross-section).

[0093] In some specific implementations, the central region is composed of polyphenylene sulfide A resin and is continuous as a whole; the edge regions are composed of polyphenylene sulfide B resin, and the resin composition of polyphenylene sulfide B in different edge regions can be the same or different.

[0094] Regarding the shape of the central region, in some preferred embodiments, the region has a rotationally symmetric structure with the fiber axis as the rotational symmetry axis. The rotational symmetry angle can be, for example, greater than 0° and less than 180°, preferably 30~180°, more preferably 45~120°, etc. Examples include 60°, 72°, 90°, etc.

[0095] In a further preferred embodiment, the central region has at least one axis of symmetry on the cross section that passes through the center point of the equivalent circle of the cross section and is located on the cross section. In some specific embodiments, there is one such axis of symmetry, and in other specific embodiments, there are two such axes of symmetry, which are orthogonal to each other.

[0096] Regarding the rotational symmetry or planar axisymmetry mentioned above in this invention, it should be noted that such "symmetry" is a judgment based on the pattern of the fiber cross-section optical microscope. Obviously, when talking about "symmetry", it refers to the "symmetry" of the corresponding pattern in a substantial or practical way. That is, such "symmetry" allows for reasonable deviations in processing accuracy and normal process errors.

[0097] Furthermore, both the central region and the edge regions extend to or form the edges of the cross-section. In some specific embodiments, the length of the edge extended or formed by the central region, based on the total length of the cross-section edges, accounts for more than 50%, preferably 60-80%, such as 65%, 70%, or 85%, while the length of the edge extended or formed by the edge regions accounts for less than 50%, preferably 10-40%, more preferably 15-30%, such as 20%, 25%, etc.

[0098] In some preferred embodiments, the central region of the cross-section of the present invention has a waist-shaped or blunt-topped trilobal shape, for example, attached Figure 2 The two cases shown. And, in the appendix... Figure 2 In this process, the polyphenylene sulfide B in each edge region can be the same or different, but it is preferred that they are the same.

[0099] Preparation of polyphenylene sulfide fibers

[0100] The polyphenylene sulfide (mono) fiber of the present invention can be obtained by melting and processing the above-mentioned polyphenylene sulfide resin raw material, spinning it, and stretching it along the axial direction.

[0101] There are no particular restrictions on the preparation method of the above single fibers in principle. In some specific embodiments, after the resin raw material is melted and spun through the corresponding spinneret, multiple traction rollers are used for traction and stretching. Furthermore, in some specific embodiments, the spinneret can be designed according to the required cross-section and form an arbitrary spinneret arrangement structure. Further, the total single-hole output of polyphenylene sulfide can be 0.3~0.6 g / min (the total amount of polyphenylene sulfide A and polyphenylene sulfide B spun in a single hole), and the spinning speed can be 1000~1500 m / min.

[0102] Optionally, the surface of the polyphenylene sulfide monofilament may be surface-treated as needed during the above-mentioned traction and stretching process.

[0103] After obtaining the above fibers, a crimping process can be used to impart crimping properties to the polyphenylene sulfide fibers.

[0104] For the curling process, conventional curling machines in the art can typically be used. When curling, it is preferable to bundle the polyphenylene sulfide monofibrils (e.g., form fiber bundles or sheets), and more preferably, to feed the bundles (fiber bundles or sheets) into the curling machine after stacking multiple layers.

[0105] Furthermore, in the above-described processing of the present invention, from the perspective of making it easier to form the desired curled structure subsequently, an oil coating treatment can be performed.

[0106] There are no particular limitations on the composition of the oiling agent; for example, various chemical fiber oiling agents available in the art can be used. In some specific embodiments, the oiling agent mainly functions to regulate the fiber's frictional properties, prevent or eliminate static electricity accumulation, and impart properties such as smoothness and easy cohesion to the fiber.

[0107] Furthermore, there are no particular restrictions on the timing of the application of the oiling agent. For example, it can be applied to the surface of polyphenylene sulfide monofibers, or to the aforementioned fiber bundles and fiber sheets, so that the surface of the polyphenylene sulfide monofibers is at least partially or completely treated or covered by the oiling agent. In some preferred embodiments, the oiling agent can be applied during the formation of polyphenylene sulfide monofibers or fiber bundles.

[0108] Furthermore, there are no particular restrictions on the method of fiber bundle formation. Ready-made single fibers can be used and bundled into fiber bundles; or single fibers obtained directly from melt-spun fibers through traction and stretching can be bundled into fiber bundles.

[0109] There are no particular limitations on the crimping process. Preferably, the polyphenylene sulfide fiber of the present invention can be given a preliminary crimped structure by processing with opposing crimping rollers. The crimped structure can be controlled by adjusting conditions such as the spacing between the crimping rollers, the temperature, and the rotation speed of the rollers.

[0110] Furthermore, the fibers that have undergone preliminary crimping by the crimping roller are then subjected to the action of two scrapers behind the crimping roller to form a complete crimping structure between the scrapers.

[0111] Furthermore, the curling shape of the curled structure can be controlled by adjusting the pressure applied by the scraper, the distance between the scraper tip and the roller edge, and the distance between the scrapers. Therefore, the "curling" in this invention refers to the curling formed by the largest self-sustaining undulation in terms of macroscopic size.

[0112] After processing by the aforementioned crimping machine, the polyphenylene sulfide fibers of the present invention acquire the desired crimped structure. Subsequently, in some preferred embodiments of the present invention, the polyphenylene sulfide fibers having the crimped structure can be dried.

[0113] The drying process of the present invention can be carried out under heating conditions. The heating and drying can remove volatile components on the fiber surface and solidify the fiber skin. On the other hand, it can also appropriately alleviate some residual stress from the crimping process and has a shaping effect.

[0114] In some other embodiments of the present invention, after the heat treatment, the resulting fibers may be cut as needed to obtain polyphenylene sulfide short fibers.

[0115] Properties of polyphenylene sulfide fibers

[0116] The polyphenylene sulfide fibers of the present invention are preferably in the form of short fibers. The length of the short fibers is typically 50 to 80 mm.

[0117] There are no particular limitations on the fineness of the polyphenylene sulfide fibers of the present invention. Generally, they can have a fineness of less than 2.8 dtex, for example, 0.7 to 2.4 dtex. Examples of fineness include 0.8 dtex, 0.9 dtex, 1.0 dtex, 1.2 dtex, 1.4 dtex, 1.6 dtex, 1.8 dtex, 2.0 dtex, 2.2 dtex, 2.4 dtex, 2.6 dtex, etc.

[0118] The strength of the polyphenylene sulfide of the present invention can be 4 cN / dtex or higher, for example, 4.1 to 4.8 cN / dtex.

[0119] Regarding the room temperature crimping characteristics of the polyphenylene sulfide of the present invention, in some specific embodiments, the number of crimps of the fiber can be 10 to 20 per 25 mm, such as 12, 14, 16, 18, etc.

[0120] In some preferred embodiments, the average curl angle of the fiber after being held under a tensile stress of 0.1 cN / dtex for 10 minutes is 50~90° / cm. For example, 55° / cm, 60° / cm, 65° / cm, 50~90° / cm, 70° / cm, 75° / cm, 80° / cm, 85° / cm, etc.

[0121] The method for measuring the average curl angle of the present invention is attached. Figure 3 As shown: A planar projection of the fiber is obtained under a tension of 0.0018 cN / dtex. A circle with a diameter of φ0.3 mm is drawn with the vertex of the crimp bow (determined by the tangent extension method) as the center. Tangents are drawn from the two "intersection points" between the circle and the fiber. The angle between these tangents is the crimp angle of the crimp bow. The average crimp angle of all crimp bows per centimeter is the average crimp angle. The tangent at the intersection point can be approximated as follows: Draw a circle with a diameter of 6 μm centered at the intersection point. The straight line passing through the intersection point of this circle and the fiber is approximately the intersection tangent.

[0122] In addition, regarding the retention of the crimp characteristics of the fiber of the present invention at room temperature, in some specific embodiments, after holding under a tensile stress of 0.1 cN / dtex for 10 minutes, the crimp recovery rate is 95~100%. Such crimp recovery rate can be measured by the change in length of the fiber crimp body before and after under the same natural state, or it can be determined by the number of crimps. For example, after the above stretching, the number of crimps of the recovered fiber can be 9.5~20 / 25mm.

[0123] <Second aspect>

[0124] In a second aspect of the present invention, a nonwoven fabric based on polyphenylene sulfide fibers described in the first aspect is provided.

[0125] The nonwoven fabric of the present invention uses at least a portion of the above-mentioned polyphenylene sulfide fibers, preferably, the nonwoven fabric of the present invention is entirely formed of the above-mentioned polyphenylene sulfide fibers.

[0126] There are no particular limitations on the nonwoven fabric formation method of the present invention. In some preferred embodiments, the nonwoven fabric can be a needle-punched nonwoven fabric.

[0127] There are no particular restrictions on the method of forming needle-punched nonwoven fabric. For example, the polyphenylene sulfide short fibers of the present invention can be processed into nonwoven fabric through processes such as carding, web laying, and needle punching.

[0128] In some specific embodiments of this invention, the basis weight of the nonwoven fabric can be 100~200 g / m². 2 The preferred value is 120~180g / m 2 Examples include 140g / m 2 160g / m 2 180g / m 2 wait.

[0129] Although the needle-punched nonwoven fabric forming process may reduce the crimp characteristics of the fibers to some extent, the polyphenylene sulfide fibers of the present invention can still maintain good crimp characteristics in the final nonwoven fabric. In some specific embodiments, the number of crimps of the polyphenylene sulfide fibers in the nonwoven fabric can be 6 to 16 crimps / 25mm, for example, 8 crimps / 25mm, 10 crimps / 25mm, 12 crimps / 25mm, and 14 crimps / 25mm.

[0130] Furthermore, the nonwoven fabric of the present invention has a reduced pore size compared to conventional polyphenylene sulfide fibers. The average pore size of the nonwoven fabric of the present invention is typically below 7 μm, preferably 4-5 μm.

[0131] Since the crimping properties of the polyphenylene sulfide fibers of the present invention can give the nonwoven fabric a reduced pore size, when forming a nonwoven fabric with the same permeability, on the one hand, the nonwoven fabric of the present invention does not need to be used with ultra-fine polyphenylene sulfide fibers, and on the other hand, when the fineness is the same, the nonwoven fabric of the present invention can use a relatively small amount of fibers.

[0132] In some preferred embodiments, the nonwoven fabric prepared from the fibers of the present invention, compared with ordinary short fibers of the same fineness, has a maximum pore size reduced by at least 20% and an average pore size reduced by at least 15% while maintaining good mechanical properties, and has a better filtration effect under the same cost conditions.

[0133] <Third aspect>

[0134] In a third aspect of the invention, an application of the nonwoven fabric described in the second aspect is provided.

[0135] Specifically, a third aspect of the present invention provides a filter bag comprising or using the nonwoven fabric described above.

[0136] Furthermore, a third aspect of the present invention also includes a flue gas filtration device, the device comprising the aforementioned filter bag. This device is suitable for filtering high-temperature flue gas generated by combustion equipment such as those used in thermal power plants, waste incineration plants, and chemical industries.

[0137] Example

[0138] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0139] Example 1 :

[0140] Polyphenylene sulfide A with a melt crystallization temperature of 185℃ and polyphenylene sulfide B with a melt crystallization temperature of 220℃ and a sulfur end group concentration of 1600 mg / kg were used as raw materials. After the resin was melted, it was fed into the system at a single-hole discharge ratio of 0.42 g / min: 0.18 g / min. Figure 4 The yarn is extruded through a circular spinneret and collected at a winding speed of 1000 m / min to obtain 6.0 dtex unextended yarn (UDY).

[0141] A crimping machine with a crimping roller-crewing side knife distance of 35mm and a crimping roller width of 200mm, as shown in Example 5, was selected to crimp the fibers. The unextended yarn was then stretched and set by 3.0 times to obtain fibers with a fineness of 2.0 dtex and a strength of 4.3 cN / dtex. (The last sentence appears to be incomplete and possibly refers to a specific fiber thickness.) 5 The total fineness of tex is fed into the crimping machine; the applied force of the crimping roller and the applied force of the crimping measuring knife are both 16×10. 4 N yielded 12 curls per 25mm, with a curl recovery rate of 95% and an average curl angle of 60°. The fiber was held under a tensile force of 0.2cN for 10 minutes, resulting in an average curl angle of 80°. The fiber was then cut into 51mm short fibers.

[0142] The above short fibers are processed through opening, weighing, carding, web laying, needle punching, roller pressing, singeing, and calendering to obtain a basis weight of 150 g / m². 2 Non-woven fabric.

[0143] Example 2 :

[0144] Polyphenylene sulfide A with a melt crystallization temperature of 185°C and polyphenylene sulfide B with a melt crystallization temperature of 260°C and a sulfur end group of 1600 mg / kg were selected as raw materials, and other aspects were the same as in Example 1.

[0145] Example 3 :

[0146] Adjust the total fineness of the feed crimping machine to 1.40×10. 5 The applied force of the tex curling roller and the applied force of the curling measuring knife are both 18×10. 4 N, the rest is the same as in Example 1.

[0147] Example 4 :

[0148] Adjust the raw material single-hole discharge ratio to 0.48 g / min: 0.12 g / min, and adjust the total fineness of the feed into the crimping machine to 1.40 × 10⁻⁶. 5 The applied force of the tex curling roller and the applied force of the curling measuring knife are both 18×10. 4 N, the rest is the same as in Example 1.

[0149] Comparative Example 1 :

[0150] Spinning was performed using the same polyphenylene sulfide A raw material as in Example 1, and everything else was the same as in Example 1.

[0151] Comparative Example 2 :

[0152] Spinning was performed using the same polyphenylene sulfide A raw material as in Example 2, and everything else was the same as in Example 1.

[0153] Comparative Example 3 :

[0154] Spinning was performed using polyphenylene sulfide B raw material, the same as in Example 1, and the rest was the same as in Example 1.

[0155] The fibers and nonwoven fabrics obtained from the above examples and comparative examples were tested. The results are shown in Table 1 below.

[0156] Table 1:

[0157]

[0158] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0159] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A polyphenylene sulfide fiber with a crimped structure, characterized in that, The polyphenylene sulfide fiber is formed by compounding at least two polyphenylene sulfide resins, and the composition and / or structure of the fiber is substantially consistent along the fiber axial direction. In any cross-section of the fiber, there exists a central region and at least two non-physically connected edge regions. The central region extends to at least a portion of the edge of the cross-section and covers the center point of the equivalent circle of the cross-section. Each edge region extends to at least a portion of the edge of the cross-section but does not cover the center point. The central region includes polyphenylene sulfide A, the edge region includes polyphenylene sulfide B, and polyphenylene sulfide A is different from polyphenylene sulfide B. Of the total area of ​​the cross-section, the area of ​​the central region is more than 50%. The crystallization temperature of polyphenylene sulfide A is lower than that of polyphenylene sulfide B, and polyphenylene sulfide B contains polar end groups in its structure.

2. The fiber according to claim 1, characterized in that, The fiber has a fineness of less than 2.8 dtex; the fiber is essentially a circular cross-section fiber.

3. The fiber according to claim 1 or 2, characterized in that, The central region extends to at least two unconnected edges of the cross section; the edges extending from the central region account for less than 80% of the total length of the edges of the cross section.

4. The fiber according to any one of claims 1 to 3, characterized in that, The central region has a shape in the cross section that is rotationally symmetric about the fiber axial direction.

5. The fiber according to any one of claims 1 to 4, characterized in that, The central region has at least one axis of symmetry passing through a neutral point on the cross section, and optionally, the central region has a gradient-varying width in a plane direction orthogonal to the axis of symmetry.

6. The fiber according to any one of claims 1 to 5, characterized in that, The cross section has 2 to 5 edge regions, and optionally, the overall shape formed by the edge regions has rotational symmetry about the fiber axial direction.

7. The fiber according to any one of claims 1 to 6, characterized in that, Each edge region uses the same or different polyphenylene sulfide B independently.

8. The fiber according to any one of claims 1 to 7, characterized in that, The crystallization temperature of polyphenylene sulfide A is below 200°C, and the crystallization temperature of polyphenylene sulfide B is above 220°C.

9. The fiber according to any one of claims 1 to 8, characterized in that, The polar end groups of the polyphenylene sulfide B include one or more of the following: mercapto, carboxyl, hydroxyl, or sulfonic acid groups.

10. The fiber according to any one of claims 1 to 9, characterized in that, The fiber has one or more of the following properties: i. The number of fiber crimps is 10~20 / 25mm; ii. The fiber fineness is 0.7~2.8 dtex; iii. The average crimp angle of the fiber after being held under a tensile stress of 0.1 cN / dtex for 10 min is 50~90° / cm; iv. The fiber strength is above 4.0 cN / dtex.

11. A nonwoven fabric, characterized in that, The nonwoven fabric comprises fibers according to any one of claims 1 to 10.

12. The nonwoven fabric according to claim 11, characterized in that, The nonwoven fabric is a needle-punched nonwoven fabric.

13. The nonwoven fabric according to claim 11 or 12, characterized in that, The nonwoven fabric has one or more of the following characteristics: a. The nonwoven fabric has a density of 100~200 g / m³. 2 The weight; b. The number of crimps of the fibers in the nonwoven fabric is 6 to 16 per 25 mm; c. The average pore size of the nonwoven fabric is less than 7 μm.

14. A filter bag, characterized in that, The filter bag includes or uses the nonwoven fabric according to any one of claims 11 to 13.

15. A flue gas filtration device, characterized in that, The device includes the filter bag according to claim 14, wherein the flue gas originates from the emissions of the combustion equipment.

Images