Polyphenylene sulfide fiber and preparation method therefor

Abstract

A polyphenylene sulfide fiber. The polyphenylene sulfide fiber is a fiber bundle formed from single fibers, wherein each single fiber comprises a single polyphenylene sulfide fiber having a fineness of 1.6 dtex or less; the fiber bundle has a primary crimp structure therein formed by the single fibers; and the fiber bundle also has a secondary crimp structure. The crimp percentage of the primary crimp structure is 11.0% or more, and the standard deviation of the crimp percentage of the primary crimp structure is 5.0% or less; and the crimp percentage of the secondary crimp structure is 22.0-35.0%. The present invention further relates to a method for preparing the polyphenylene sulfide fiber, a non-woven fabric comprising the polyphenylene sulfide fiber, and a dust collection device comprising the non-woven fabric. The polyphenylene sulfide fiber has good carding performance in a carding process, and can also achieve a good uniformity and good surface properties.

Description

Polyphenylene sulfide fiber and its preparation method Technical Field

[0001] This invention belongs to the field of production and processing of polymer products, and relates to a polyphenylene sulfide fiber and its preparation method. More specifically, it relates to a polyphenylene sulfide fiber with two-stage crimping characteristics based on fine denier fibers and its preparation method. Background Technology

[0002] Polyphenylene sulfide (PPS), as one of the six major special engineering plastics, has excellent comprehensive properties, including good chemical resistance, high temperature resistance, flame retardancy, good dimensional stability, and low creep. It is widely used as a structural polymer material.

[0003] Polyphenylene sulfide (PPS) materials are typically used to prepare a variety of high-quality fiber products. PPS fibers are mainly produced through melt spinning. For example, nascent fibers are formed by condensing the melt stream flowing out of a spinning spinneret, and then obtaining various desired stretched fibers through subsequent stretching, heat treatment, and other methods.

[0004] Polyphenylene sulfide fiber is widely used for filtration and dust removal of flue gas from coal-fired power plants and municipal solid waste incineration plants due to its good mechanical properties, high temperature resistance and corrosion resistance.

[0005] Reference 1 discloses a polyphenylene sulfide short fiber, which controls the single fiber fineness to 0.70-0.95 dtex, the strength to 4.5-5.5 cN / dtex, the fiber length to 20-100 mm, and the melt flow rate to 200-295 g / 10 min. This provides a polyphenylene sulfide short fiber that does not reduce fiber productivity and felt productivity, but also improves dust collection performance and mechanical strength.

[0006] Reference 2 provides a polyphenylene sulfide short fiber with good thermal insulation, heat resistance, and bulkiness. These properties are achieved by controlling the fiber's hollowness, fineness, crimp characteristics, and frictional properties.

[0007] Furthermore, for the production process of nonwoven fabrics based on fine denier fibers, the finer fiber diameter presents disadvantages (such as mechanical properties and electrostatic factors leading to processing difficulties). Currently, research has been conducted to some extent in this field, particularly on improving the process for producing nonwoven fabrics using fine denier fibers.

[0008] References 3 and 4 describe how the selection of polyolefin resins and the use of components with hydrophilic groups can form composite ultrafine denier fibers, thereby reducing static electricity and reducing cotton knots, and improving the combing passability during carding.

[0009] Reference 5 describes a process where a low-crystallinity polyester (B) is used to wrap a high-crystallinity polymer (A) to form a bundle of ultrafine denier fibers during spinning. This allows the ultrafine denier fibers to be easily combed and the wrapping is removed in the subsequent hydroentangling process.

[0010] However, although some research has been conducted on fine denier fibers of various materials in this field, there is still room for further improvement on fine denier polyphenylene sulfide fibers, especially fine denier polyphenylene sulfide fibers suitable for needle-punched nonwoven fabric processes and their preparation methods.

[0011] References:

[0012] Reference 1: CN111433395A

[0013] Reference 2: JP 2017-133117A

[0014] Reference 3: US5965084A

[0015] Reference 4: JP3525556B2

[0016] Reference 5: US6737004B2 Summary of the Invention

[0017] The problem the invention aims to solve

[0018] In the field of high-temperature dust removal materials, considering the complex and harsh operating conditions of the equipment, high requirements are placed on the mechanical properties, temperature resistance, and corrosion resistance of resin materials. Compared with polyphenylene sulfide fibers, general polyolefin fibers, ordinary polyester fibers, and other materials cannot meet the application requirements.

[0019] In addition, for fine denier fibers, due to their extremely fine fineness, in the preparation of nonwoven fabrics, especially in the preparation of needle-punched nonwoven fabrics, the strong interaction between the extremely fine fibers can lead to unsmooth processing or unevenness and poor surface properties in the final nonwoven fabric product.

[0020] Reference 1 states that by controlling the fineness, strength, and melt properties of single fibers, both fiber productivity and felt productivity can be achieved. However, it does not directly address the smoothness of the web exit during high-speed web exit in nonwoven fabric preparation, as well as the uniformity and good surface properties of the final product.

[0021] Reference 2 also did not directly address the aforementioned issues.

[0022] While references 3-5 involve the modification of polyolefin and polyester fine denier fibers, such methods are clearly not applicable to the processing or treatment of polyphenylene sulfide fine denier fibers.

[0023] Based on this, the present invention primarily provides a polyphenylene sulfide fiber suitable for the preparation of nonwoven fabrics, especially needle-punched nonwoven fabrics. It is a polyphenylene sulfide fiber bundle comprising polyphenylene sulfide monofibers with a fineness of less than 1.6 dtex. By crimping the fiber bundle to impart specific primary and secondary crimp structure characteristics, the fiber bundle can effectively avoid the formation of neps and improve the throughput of the carding process in the preparation of nonwoven fabrics, resulting in nonwoven fabric products with good uniformity and surface properties. In addition, it can also significantly improve the production efficiency of nonwoven fabrics.

[0024] Solution for solving the problem

[0025] Through long-term research, the inventors of this invention have discovered that the above-mentioned technical problems can be solved by implementing the following technical solution:

[0026] [1]. This invention first provides a polyphenylene sulfide fiber, wherein the polyphenylene sulfide fiber is a fiber bundle formed from monofibers, wherein the monofibers include polyphenylene sulfide monofibers with a fineness of less than 1.6 dtex, and,

[0027] The fiber bundle has a primary crimp structure formed by the single fiber, and the fiber bundle also has a secondary crimp structure.

[0028] in,

[0029] The curl rate of the primary curl structure is 11.0% or more, and the standard deviation of the curl rate of the primary curl structure is 5.0% or less;

[0030] The curl rate of the secondary curl structure is 22.0% to 35.0%.

[0031] [2]. The polyphenylene sulfide fiber according to [1], wherein the fineness of the polyphenylene sulfide monofiber is 0.5 to 1.4 dtex.

[0032] [3]. The polyphenylene sulfide fiber according to [1] or [2], wherein the fiber bundle is formed by bundling the polyphenylene sulfide monofibers.

[0033] [4]. The polyphenylene sulfide fiber according to any one of [1] to [3], wherein the polyphenylene sulfide fiber has a total fineness of 1.0 × 10⁻⁶. 5 ~2.0×10 5 The primary and secondary curled structures are obtained by performing curling processing under tex.

[0034] [5]. The polyphenylene sulfide fiber according to any one of [1] to [4], wherein the crimp rate of the primary crimp structure is 11.0% to 15.0%; and the standard deviation of the crimp rate of the primary crimp structure is less than 3.0%.

[0035] [6]. The polyphenylene sulfide fiber according to any one of [1] to [5], wherein the crimp rate of the secondary crimp structure is 25.0% to 32.0%.

[0036] [7]. Polyphenylene sulfide fiber according to any one of [1] to [6], wherein the surface of the polyphenylene sulfide monofiber is at least partially treated with an oiling agent.

[0037] [8]. Furthermore, the present invention also provides a method for preparing polyphenylene sulfide fibers, particularly the method for preparing polyphenylene sulfide fibers described in the above-mentioned items, wherein the method includes:

[0038] Polyphenylene sulfide fiber bundles, including polyphenylene sulfide monofibers with a fineness of less than 1.6 dtex, are crimped using a crimping machine.

[0039] Before the crimping process is performed in the crimping machine, at least part of the surface of the individual fibers in the fiber bundle is treated with an oiling agent;

[0040] In the crimping machine process, the single fiber is sequentially formed into a primary crimp structure, and the fiber bundle is formed into a secondary crimp structure.

[0041] The curl rate of the primary curl structure is 11.0% or more, and the standard deviation of the curl rate of the primary curl structure is 5.0% or less;

[0042] The curl rate of the secondary curl structure is 22.0% to 35.0%.

[0043] [9]. According to the method of [8], the fiber bundles are assembled into sheet-like fiber sheets and then fed into the crimping machine for the crimping process.

[0044]

[0010] . According to the method described in [9], a plurality of sheet-like fiber sheets are stacked and then fed into the winding machine, wherein the alignment deviation between any two adjacent fiber sheets does not exceed 15 mm.

[0045]

[0011] . The method according to any one of [8] to

[0010] , wherein the method further comprises: after processing in the crimping machine, the obtained polyphenylene sulfide fiber is further subjected to drying treatment.

[0046]

[0012] . In addition, the present invention also provides a nonwoven fabric, wherein the nonwoven fabric includes or uses polyphenylene sulfide fibers according to any one of [1] to [7] above.

[0047]

[0013] . The nonwoven fabric according to

[0012] is a needle-punched nonwoven fabric.

[0048]

[0014] . In addition, the present invention also provides a vacuum cleaner, wherein the vacuum cleaner includes or uses the nonwoven fabric described in

[0012] or

[0013] .

[0049] The effects of the invention

[0050] By implementing the above technical solutions, the present invention can achieve the following technical effects:

[0051] 1) This invention uses fiber bundles formed by polyphenylene sulfide fine denier single fibers to perform crimping treatment, thereby controlling the crimping characteristics of the primary and secondary crimping structures, so that the final polyphenylene sulfide fibers can be better suited for the preparation of nonwoven fabrics. In particular, during the nonwoven fabric production process, it can avoid the formation of knots, improve the carding passability in the carding process, and make the obtained nonwoven fabric more uniform and have good appearance and mechanical properties.

[0052] 2) When using the polyphenylene sulfide fiber described above in this invention for nonwoven fabric processing, the processing efficiency of nonwoven fabric can be significantly improved.

[0053] 3) The present invention further adjusts and optimizes the preparation method of polyphenylene sulfide fiber to make it easier to obtain the above-mentioned two-stage crimped structure and crimped characteristics of polyphenylene sulfide fiber. Attached Figure Description

[0054] Figure 1: Schematic diagram of the primary curl structure and the secondary curl structure in this invention.

[0055] Figure 2: Schematic diagram of the calculation of the curl rate of the two-stage curl structure of the present invention.

[0056] Figure 3: A schematic diagram of the structure and operation of the curling machine used in a specific embodiment of the present invention. Detailed Implementation

[0057] 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:

[0058] 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.

[0059] Unless otherwise stated, in this instruction manual, "more" in "multiple", "various", "multiple", etc., means a value of 2 or more.

[0060] In this specification, the terms "substantially" or "truly" mean that the error is less than 1%, or less than 0.8%, or less than 0.6% compared to the relevant perfect or theoretical standard. Furthermore, when "all" or "entire" is used in this specification, it also means "all" or "entire" in the sense of "substantially" or "truly".

[0061] Unless otherwise specified, "%" in this instruction manual refers to the percentage content by mass.

[0062] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0063] In this specification, when referring to "fiber" or "polyphenylene sulfide fiber," unless otherwise specified, it refers to a fiber bundle formed from a single fiber. Alternatively, it can be understood that when referring to a single fiber, the present invention uses "single fiber" or "monofilament."

[0064] 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.

[0065] 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.

[0066] 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.

[0067] In this instruction manual, "normal temperature" or "room temperature" refers to an indoor ambient temperature of "23±2℃".

[0068] The present invention primarily provides a polyphenylene sulfide fiber particularly suitable for the preparation of nonwoven fabrics and a method for its preparation. The present invention is mainly based on the following insights:

[0069] While polyphenylene sulfide (PPS) fibers possess excellent mechanical properties, heat resistance, and chemical stability, their application in nonwoven fabric production, particularly those based on fine denier monofibrils, often results in poor carding throughput during processing (e.g., neps formation and difficulty in web exiting), leading to suboptimal product quality, uniformity, and surface finish. This invention addresses this issue by controlling the crimp characteristics of the primary and secondary crimp structures of PPS fiber bundles based on fine denier monofibrils. This allows PPS fibers to exhibit excellent carding throughput during the carding process, while also achieving good uniformity and surface finish.

[0070] <First Aspect>

[0071] In a first aspect of the invention, a polyphenylene sulfide (PPS) fiber bundle comprising fine denier monofibers is provided. In some preferred embodiments of the invention, the PPS fiber is formed by bundling these fine denier PPS monofibers.

[0072] Polyphenylene sulfide resin raw materials

[0073] There are no particular limitations on the polyphenylene sulfide resin raw materials used in the polyphenylene sulfide single fibers and fiber bundles of the present invention. Various raw materials and synthesis routes in the art can be used to obtain polyphenylene sulfide resins.

[0074] For example, the polyphenylene sulfide resin of the present invention is mainly formed of a polymer containing repeating units as follows:

[0075] 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.

[0076] In some specific embodiments, the polyphenylene sulfide resin can be obtained by polymerizing sodium sulfide and p-dichlorobenzene in an organic solvent. Additionally, optional additives or capping agents can be used as needed during the synthesis of the above-mentioned polyphenylene sulfide resin.

[0077] Furthermore, in some specific embodiments of the polyphenylene sulfide resin raw material of the present invention, its weight-average molecular weight can be 30,000 to 90,000, preferably 40,000 to 80,000, and more preferably 45,000 to 55,000. Specific examples include 35,000, 45,000, 55,000, 60,000, and 65,000, etc. Within the above molecular weight range, both mechanical strength and processability are considered. If the molecular weight is too high, it may lead to excessively high requirements for equipment in subsequent monofilament preparation and may cause production instability. If the molecular weight is too low, there are concerns about insufficient mechanical properties and heat resistance.

[0078] Furthermore, the molecular weight distribution of the polyphenylene sulfide resin of the present invention is not particularly limited in principle, but from the perspective of fiber mechanical strength, a narrower molecular weight distribution is preferred. For example, the molecular weight distribution index of the polyphenylene sulfide resin of the present invention can be 3.8 or less, 3.6 or less, and more 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, thereby improving the fiber density and achieving the purpose of improving initial mechanical strength.

[0079] Polyphenylene sulfide monofiber

[0080] The polyphenylene sulfide monofiber of the present invention can be obtained by melting and processing the above-mentioned polyphenylene sulfide resin raw material and then spinning and stretching it.

[0081] There are no particular restrictions on the preparation method of the above-mentioned monofibers. In some specific implementations, after the resin raw material is melted and spun, multiple traction rollers can be used for traction and stretching. Optionally, the surface of the polyphenylene sulfide monofilament can be surface-treated as needed during the above-mentioned traction and stretching process.

[0082] Furthermore, the polyphenylene sulfide monofiber of the present invention is a fine denier monofiber. In some specific embodiments of the present invention, the fineness of such a fine denier monofiber can be below 1.6 dtex. Considering processability, usability, mechanical properties, and heat resistance, the fineness of the monofiber is preferably 0.5 to 1.4 dtex, and examples of fineness include 0.6 dtex, 0.7 dtex, 0.8 dtex, 0.9 dtex, 1.0 dtex, 1.1 dtex, 1.2 dtex, 1.3 dtex, 1.5 dtex, etc.

[0083] Polyphenylene sulfide fiber

[0084] The polyphenylene sulfide fiber of the present invention is a bundle of fibers including the above-mentioned polyphenylene sulfide monofibrils, i.e., fiber bundle fiber.

[0085] In some specific embodiments of the present invention, the polyphenylene sulfide fiber of the present invention may include the polyphenylene sulfide monofiber of the present invention as described above, as well as other monofibers. Preferably, based on the total mass of the polyphenylene sulfide fiber, the content of the polyphenylene sulfide monofiber of the present invention may be 80.0% by mass or more, more preferably 90.0% by mass or more, even more preferably 95.0% by mass or more, and even more preferably 98.0% by mass or more.

[0086] In some other specific embodiments of the present invention, the polyphenylene sulfide fibers of the present invention are substantially all composed of the polyphenylene sulfide monofibers described above.

[0087] There are no particular restrictions in principle on the method of forming fiber bundles from single fibers, and it can be done by conventional bundling methods in this field.

[0088] Furthermore, when the polyphenylene sulfide fiber of the present invention is used in the form of short fibers, the length of the short fibers can be less than 200 mm, preferably 10 to 170 mm, more preferably 20 to 150 mm, and even more preferably 30 to 120 mm. The length of the short fibers described in the present invention refers to the straightened length of the fiber (the length when tension is relieved but no additional tensile force is generated).

[0089] Furthermore, it is advantageous for the polyphenylene sulfide fiber of the present invention to have a suitable degree of crystallinity. In some preferred embodiments, the crystallinity of the polyphenylene sulfide fiber can be 20-50%, more preferably 30-40%. This degree of crystallinity can be determined by measuring data using a differential scanning calorimeter under nitrogen atmosphere at a heating rate of 10°C / min.

[0090] crimping structure characteristics of polyphenylene sulfide fibers

[0091] The polyphenylene sulfide fibers of the present invention are crimped to have a specific two-stage crimp structure, and it has been found that by satisfying such two-stage crimp structure characteristics, the polyphenylene sulfide fibers of the present invention can be endowed with significantly improved carding passability and increased production efficiency in the process of preparing nonwoven fabrics.

[0092] (Level 1 curl structure)

[0093] The primary curled structure of the present invention refers to the curled structure formed by the curling of individual fibers inside the polyphenylene sulfide fiber bundle of the present invention (see the schematic diagram of the "primary curled" structure in Figure 1 for details). For such a curled structure, the curl rate can be above 11.0%.

[0094] In some preferred embodiments of the present invention, the crimp rate of the primary crimp structure can be 11.0% to 15.0%. If the crimp rate is too low, there are concerns about poor processability in subsequent nonwoven fabric processing and a small surface area per unit volume in the final nonwoven fabric product, which is detrimental to dust removal and adsorption. Furthermore, although there is no specific upper limit on the crimp rate in principle, it is believed that if the crimp rate is too high, it may cause processing difficulties and result in excessive air permeability resistance in the final nonwoven fabric.

[0095] Furthermore, the curling rates that can be listed for the primary curling structure of the present invention include 11.2%, 11.4%, 11.6%, 11.8%, 12.0%, 12.2%, 12.4%, 12.6%, 12.8%, 13.0%, 13.2%, 13.4%, 13.6%, 13.8%, 14.0%, 14.2%, 14.4%, 14.6%, and 14.8%, etc.

[0096] The crimp rate described above in this invention can be obtained by calculating the crimp rate according to the method in Section 8.2 of GB / T 14338 "Test Method for Crimping Properties of Short Fibers".

[0097] Furthermore, considering the good processability of the subsequent nonwoven fabric, the standard deviation of the crimp rate in the primary crimp structure of the present invention is controlled to be below 5.0%. In some preferred embodiments, the standard deviation of the crimp rate of the primary crimp structure is below 3.0%, for example, 1.0% to 2.5%. An excessively large standard deviation of the crimp rate in the primary crimp will lead to poor processability and poor product uniformity during subsequent nonwoven fabric processing.

[0098] (Two-dimensional curl structure)

[0099] The secondary crimp structure of the present invention refers to the crimp structure formed or present in the polyphenylene sulfide fiber bundle itself (see the schematic diagram of the "secondary crimp" structure in Figure 1 for details). Therefore, the secondary crimp structure of the present invention can be regarded as the external crimp structure of the polyphenylene sulfide fiber, while the primary crimp structure described above can be regarded as the internal crimp structure of the polyphenylene sulfide fiber.

[0100] Furthermore, for the secondary crimping structure of the present invention, the crimp rate is controlled to be 22.0% to 35.0%. If the crimp rate of the secondary crimping is too low or too high, it will lead to poor throughput of the carding process in the preparation of nonwoven fabric and result in poor surface properties of the final nonwoven fabric product.

[0101] In some preferred embodiments of the present invention, the curl rate of the secondary curl structure is preferably 25.0% to 32.0%, and can be further specifically listed as 25.4%, 25.8%, 26.0%, 26.4%, 26.8%, 27.0%, 27.4%, 28.0%, 28.4%, 28.8%, 29.0%, 29.4%, 29.8%, 30.0%, 30.4%, 30.8%, 31.0%, 31.4%, 31.8%, 32.4%, 32.8%, 33.0%, 33.4%, 33.8%, 34.0%, 34.4%, and 34.8%, etc.

[0102] <Second aspect>

[0103] In a second aspect of the present invention, a method for preparing polyphenylene sulfide fiber is provided, and in particular, the method for preparing polyphenylene sulfide fiber described in the first aspect above is applicable.

[0104] It should be noted that the formation of the two-stage crimp of the polyphenylene sulfide fiber described or defined in the first aspect of this invention can be obtained by various crimping processing methods. It is understood that the influencing factors on these structures may be related to processing equipment and control methods. Therefore, the above-mentioned two-stage crimp structure should not be understood as depending on a single or certain specific preparation process.

[0105] However, through long-term practice in fiber preparation and nonwoven fabric preparation, it has been found that the following processing technology can more efficiently obtain the two-stage crimped structure defined in this invention, while also having good operability.

[0106] Specifically, the method for preparing polyphenylene sulfide fiber provided by the present invention may include the following steps:

[0107] Polyphenylene sulfide fiber bundles, including polyphenylene sulfide monofibers with a fineness of less than 1.6 dtex, are crimped using a crimping machine.

[0108] Before the crimping process is performed in the crimping machine, at least part of the surface of the individual fibers in the fiber bundle is treated with an oiling agent;

[0109] In the crimping process, the single fiber is sequentially formed into a primary crimp structure, and the fiber bundle is formed into a secondary crimp structure.

[0110] Specifically:

[0111] Pre-processing

[0112] The pretreatment process of this invention refers to the process that the polyphenylene sulfide fiber to be crimped can undergo before the crimping process.

[0113] There are no special requirements for such procedures in principle. However, in some specific implementation schemes, these pretreatment procedures may include one or more of the following processes:

[0114] i. Bundling polyphenylene sulfide monofibers to obtain polyphenylene sulfide fibers as fiber bundles;

[0115] ii. Bundle the polyphenylene sulfide fibers into sheets (polyphenylene sulfide fiber sheets / filaments);

[0116] iii. Feed the polyphenylene sulfide fiber sheet or a laminate of multiple such fiber sheets into a winding machine.

[0117] Furthermore, in the pretreatment stage of the present invention, from the perspective of making it easier to form the desired two-stage curled structure in the future, an oil treatment can be performed.

[0118] 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.

[0119] In some specific embodiments of the present invention, the oiling agent may include one or more of the following: antistatic agent, smoothing agent, cohesive agent, antioxidant, oiling agent solvent, emulsifier or modifier.

[0120] 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.

[0121] Furthermore, there are no particular restrictions on the source of polyphenylene sulfide monofibers or fiber bundles in step i. Ready-made monofibers can be used and bundled into fiber bundles; or monofibers obtained directly from melt spinnerets through traction and stretching can be bundled into fiber bundles.

[0122] Curling process

[0123] The crimping process of this invention can be performed in various crimping machines in the art. Furthermore, there is no particular limitation on the total fineness of the polyphenylene sulfide fibers fed into the winding machine during the crimping process of this invention. From the perspective of processing and ease of use, the total fineness of the polyphenylene sulfide fibers can be 1.0 × 10⁻⁶. 5 ~2.0×10 5tex, preferably 1.4 × 10 5 ~1.8×10 5 TeX, examples of which include 1.5 × 10⁻⁶, can be listed. 5 tex, 1.6×10 5 tex, 1.7×10 5 tex and 1.9×10 5 TeX, etc.

[0124] Furthermore, in some specific embodiments of the present invention, a curling processing machine having the various components shown in FIG3 can be used.

[0125] Figure 3 schematically shows the various components of the crimping machine, including two opposing crimping rollers and two scrapers positioned behind the crimping rollers (based on the fiber running direction).

[0126] As described above, the present invention can feed fiber sheets into the gap between opposing crimping rollers for crimping.

[0127] For the aforementioned fiber sheets (filaments), it is preferable to use composite sheets of multiple fiber sheets, such as composite sheets formed of 2 to 5 layers of filaments. In some preferred embodiments of the present invention, it has been found that when using composite sheets, a higher degree of alignment between multiple filaments is more beneficial to the crimped structure of the present invention, especially to the more uniform formation of the primary crimped structure, thereby affecting the smoothness of processing of the obtained polyphenylene sulfide fibers in the preparation of nonwoven fabrics.

[0128] In some preferred embodiments, in the composite sheet described above, the alignment deviation between two adjacent filaments is set as e, and each e preferably does not exceed 15 mm.

[0129] Furthermore, during the crimping process, the width of the fiber sheet fed into the crimping machine can be less than 100% of the processing width of the opposing crimping rollers, preferably 95% to 99%, to balance processing convenience and processing efficiency.

[0130] As shown in Figure 3, the polyphenylene sulfide fiber of the present invention can be given a primary crimp structure through processing with opposing crimping rollers. The primary crimp structure can be controlled by adjusting conditions such as the spacing between the crimping rollers, temperature, and roller rotation speed.

[0131] Furthermore, the fibers that have undergone primary crimping structure processing by the crimping roller are then subjected to the action of two scrapers behind the crimping roller, forming a secondary crimping structure between the scrapers.

[0132] Furthermore, the curling shape of the secondary curling 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.

[0133] Post-processing

[0134] After processing by the aforementioned crimping machine, the polyphenylene sulfide fibers of the present invention acquire the desired two-stage crimp structure. Subsequently, in some preferred embodiments of the present invention, the polyphenylene sulfide fibers having the two-stage crimp structure can be dried.

[0135] 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.

[0136] 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.

[0137] <Third aspect>

[0138] In a third aspect of the present invention, a nonwoven fabric and a vacuuming device are provided.

[0139] The nonwoven fabric of the present invention can be a nonwoven fabric comprising or using the polyphenylene sulfide fibers described in the first aspect of the present invention. In some preferred embodiments, the nonwoven fabric is a needle-punched nonwoven fabric.

[0140] The vacuum cleaner of the present invention can be a vacuum filter device, and the vacuum cleaner includes or uses the above-mentioned non-woven fabric.

[0141] In some preferred embodiments, the vacuuming device includes an adsorption / filtration component that comprises or uses the aforementioned nonwoven fabric layer, and optionally, the component may also have a support component that is composite with the nonwoven fabric.

[0142] Example

[0143] 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.

[0144] Example 1

[0145] A crimping machine with a crimping roller-crew cutter distance of 35mm and a crimping roller width of 200mm was selected to crimp ultrafine denier polyphenylene sulfide fibers. Before the fibers enter the crimping machine, an oiling agent is applied, and then three filaments are stacked. The overlap distance (i.e., alignment deviation) between any two adjacent filaments is controlled within 8±1mm, with a single filament fineness of 0.84 dtex and a fiber density of 1.55×10⁻⁶. 5 The total fineness of the tex (the total fineness of all polyphenylene sulfide fibers fed into the crimping machine) 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. The resulting polyphenylene sulfide fibers are then dried.

[0146] Example 2

[0147] Same as Example 1, except that: the offset distance between any two adjacent sheets is controlled at 14±1mm, with a single filament fineness of 0.95dtex and 1.60×10 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.

[0148] Example 3

[0149] Same as Example 1, except that: the offset distance between any two adjacent sheets is controlled within 5±1 mm, with a single filament fineness of 1.39 dtex and a diameter of 1.65 × 10⁻⁶ mm. 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.

[0150] Example 4

[0151] Same as Example 1, except that: two filaments are stacked, with the stacking offset distance controlled at 14±1mm, and the single filament fineness is 1.60dtex, 1.70×10 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.

[0152] Comparative Example 1

[0153] Same as Example 1, except that: no oil is applied before crimping, and the offset distance between any two adjacent sheets is controlled within 20±1mm, with a single filament fineness of 1.07dtex and 1.55×10 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 4×10. 4 N, after being processed by the crimping machine, the resulting polyphenylene sulfide fibers were not dried.

[0154] Comparative Example 2

[0155] Same as Example 1, except that: the offset distance between any two adjacent sheets is controlled at 17±1mm, with a single filament fineness of 0.78dtex and 0.83×10 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 8×10. 4 N.

[0156] Comparative Example 3

[0157] Same as Example 1, except that: no oil is applied before crimping, and the offset distance between any two adjacent sheets is controlled within 8±1 mm, with a single filament fineness of 0.95 dtex and 2.21×10 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 90×10. 4 N.

[0158] Comparative Example 4

[0159] Same as Example 1, except that: the offset distance between any two adjacent sheets is controlled within 1±1 mm, with a single filament fineness of 1.65 dtex and 2.21×10 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 15×10. 4 N, after being processed by the crimping machine, the resulting polyphenylene sulfide fibers were not dried.

[0160] Comparative Example 5

[0161] Same as Example 1, except that: the offset distance between any two adjacent sheets is controlled at 17±1mm, with a single filament fineness of 1.12dtex and 2.14×10 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 65×10. 4 N.

[0162] Comparative Example 6

[0163] Same as Example 1, except that: the offset distance between any two adjacent sheets is controlled within 10±1 mm, with a single filament fineness of 1.12 dtex and 2.14×10 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 20 × 10. 4 N.

[0164] Comparative Example 7

[0165] Commercially available fine denier fibers, compared to Example 1, are not oiled before crimping, and the offset distance between any two adjacent filaments is controlled within 10±1 mm, with a single filament fineness of 0.89 dtex and a fiber density of 1.55×10⁻⁶.5 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 20 × 10. 4 N.

[0166] The fibers obtained from the above embodiments and comparative examples were subjected to crimping characteristics measurement and nonwoven fabric preparation, wherein the tests were conducted according to the following measurement and evaluation methods:

[0167] 1) Measurement method for the curl rate of primary curled structures

[0168] Curl rate: The calculation shall be performed in accordance with the calculation method of "curl rate" in Section 8.2 of GB / T 14338 "Test method for crimp performance of short fibers".

[0169] 2) Standard deviation of curl rate of primary curl structure

[0170] Curl distribution: standard deviation of 20 fiber curl rates.

[0171] 3) Method for measuring the curl rate of secondary curled structures:

[0172] The equivalent rectangle method is used for measurement: the short fiber bundle is laid flat on the plane in its natural state without tensile stress, and the plane projection shown in Figure 3 is obtained. The minimum rectangle containing the fiber bundle is constructed with the line connecting the two ends of the short fiber bundle, or the line from one end of the fiber to the tangent of the fiber as the longitudinal side (a), and the other side is the transverse side (b). The secondary crimp rate = transverse side length ÷ longitudinal side length × 100%.

[0173] A total of 20 short fiber bundles were measured in each measurement, and the average value was taken.

[0174] 4) Network connectivity:

[0175] Net exit passability: The situation when exiting the net at a speed of 30m / min.

[0176] ◎ indicates that when exiting the net at a speed of 30m / min, uniform and smooth continuous net exit is achieved;

[0177] △ indicates that continuous net exits are possible when exiting the net at a speed of 30m / min;

[0178] × indicates that it is impossible to leave the net when the speed is 30m / min.

[0179] Specifically:

[0180] ◎ indicates: 20g / m 2The net was combed at a speed of 30m / min, producing 200m of net continuously. A 2m sample was taken at the very beginning of production, another 2m sample at 100m, and a final 2m sample at the end of the 200m production run, for a total of three samplings. From these three samples, 10cm side-length samples were cut from nine equally spaced points, resulting in a total of 27 samples. The weight of each sample was measured, and the average weight was found to be 15g / m². 2 ~25g / m 2 The results were judged to indicate good uniformity and good productivity.

[0181] △ indicates: 20g / m 2 The net was combed at a speed of 30m / min, producing 200m of net continuously. A 2m sample was taken at the very beginning of production, another 2m sample at 100m, and a final 2m sample at the end of the 200m production run, for a total of three samplings. From these three samples, 10cm side-length samples were cut from nine equally spaced points, resulting in a total of 27 samples. The weight of each sample was measured, and the average weight was found to be 15g / m². 2 Below or 25g / m 2 The above assessment indicates that the uniformity and productivity are acceptable.

[0182] × indicates: 20g / m 2 The net was combed out at a speed of 30m / min, but it could not be successfully combed out, and was therefore judged as unproductive ×.

[0183] 5) Uniformity of the final nonwoven fabric

[0184] The test was conducted in accordance with GB / T 24218.1 "Textiles - Nonwoven Fabrics: Test Methods - Determination of Mass per Unit Area". Ten 25cm × 25cm nonwoven fabric samples were cut and their weights were measured. A weight deviation rate (%) of less than 3% indicates excellent uniformity and surface properties; a deviation rate (%) of 3-10% indicates acceptable uniformity and surface properties; and a deviation rate (%) > 10% indicates poor uniformity and the presence of obvious cotton knots on the surface.

[0185] The detection and evaluation data for the above embodiments and comparative examples are shown in Table 1 below.

[0186] Table 1:

[0187] It is evident that the technical solution that satisfies the two-stage crimp structure characteristics of polyphenylene sulfide fiber of the present invention can give the nonwoven fabric better web exit passability during processing, and the final nonwoven fabric also has good uniformity.

[0188] Furthermore, by optimizing the preparation conditions of polyphenylene sulfide fibers, the two-stage crimped structure desired by this invention can be obtained more easily.

[0189] 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.

[0190] 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, characterized in that, The polyphenylene sulfide fiber is a fiber bundle formed from single fibers, wherein the single fibers include polyphenylene sulfide single fibers with a fineness of less than 1.6 dtex, and, The fiber bundle has a primary crimp structure formed by the single fiber, and the fiber bundle also has a secondary crimp structure. in, The curl rate of the primary curl structure is 11.0% or more, and the standard deviation of the curl rate of the primary curl structure is 5.0% or less; The curl rate of the secondary curl structure is 22.0% to 35.0%.

2. The polyphenylene sulfide fiber according to claim 1, characterized in that, The fineness of the polyphenylene sulfide monofiber is 0.5 to 1.4 dtex.

3. The polyphenylene sulfide fiber according to claim 1 or 2, characterized in that, The fiber bundle is formed by bundling the polyphenylene sulfide monofibrils.

4. The polyphenylene sulfide fiber according to any one of claims 1 to 3, characterized in that, The polyphenylene sulfide fibers have a total fineness of 1.0 × 10⁻⁶. 5 ~2.0×10 5 The primary and secondary curled structures are obtained by performing curling processing under tex.

5. The polyphenylene sulfide fiber according to any one of claims 1 to 4, characterized in that, The curl rate of the primary curl structure is 11.0% to 15.0%; the standard deviation of the curl rate of the primary curl structure is less than 3.0%.

6. The polyphenylene sulfide fiber according to any one of claims 1 to 5, characterized in that, The curl rate of the secondary curl structure is 25.0% to 32.0%.

7. The polyphenylene sulfide fiber according to any one of claims 1 to 6, characterized in that, The surface of the polyphenylene sulfide monofiber is at least partially treated with an oiling agent.

8. A method for preparing polyphenylene sulfide fiber, characterized in that, The method includes: Polyphenylene sulfide fiber bundles, including polyphenylene sulfide monofibers with a fineness of less than 1.6 dtex, are crimped using a crimping machine. Before the crimping process is performed in the crimping machine, at least part of the surface of the individual fibers in the fiber bundle is treated with an oiling agent; In the crimping machine process, the single fiber is sequentially formed into a primary crimp structure, and the fiber bundle is formed into a secondary crimp structure. The curl rate of the primary curl structure is 11.0% or more, and the standard deviation of the curl rate of the primary curl structure is 5.0% or less; The curl rate of the secondary curl structure is 22.0% to 35.0%.

9. The method according to claim 8, characterized in that, The fiber bundles are assembled into sheet-like fiber sheets and then fed into the crimping machine for crimping.

10. The method according to claim 9, characterized in that, Multiple sheet-like fiber sheets are stacked and then fed into the winding machine, with the alignment deviation between any two adjacent fiber sheets not exceeding 15 mm.

11. The method according to any one of claims 8 to 10, characterized in that, The method further includes drying the obtained polyphenylene sulfide fibers after processing in the crimping machine.

12. A nonwoven fabric, characterized in that, The nonwoven fabric includes or uses polyphenylene sulfide fibers according to any one of claims 1 to 7.

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

14. A vacuum cleaner, characterized in that, The vacuuming device includes or uses the nonwoven fabric according to claim 12 or 13.

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