Method for producing polyphenylene sulfide fiber and polyphenylene sulfide fiber

Abstract

To provide a polyphenylene sulfide fiber enabling efficient fiber production with good operability in spinning and drawing processes through selection of a specific oil agent, and ensuring quality improvement by reducing fluff and monofilament breakage.SOLUTION: Provided is a production method for a polyphenylene sulfide fiber having p-phenylene sulfide units as its main constituent unit, wherein, as an oil agent component, an oil agent containing 5 to 100 mass% of octyl phosphonate based on the total oil agent components is attached so that the oil adhesion amount is 0.3 mass% to 1.5 mass%. Further provided is a polyphenylene sulfide fiber having p-phenylene sulfide units as its main constituent unit, wherein, as an oil agent component, an oil agent containing 5 to 100 mass% of octyl phosphonate based on the total oil agent components is attached so that the oil adhesion amount is 0.3 mass% to 1.5 mass%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to polyphenylene sulfide fibers and a method for producing polyphenylene sulfide fibers.

Background Art

[0002] Industrial filters currently widely use mesh fabrics made of polyphenylene sulfide, polyvinylidene fluoride, liquid crystal polyester, etc. from the viewpoints of chemical resistance, dimensional stability, heat durability, etc. In particular, polyphenylene sulfide fabrics are excellent in chemical resistance, dimensional stability and cost performance, and are widely used because they are suitable for fields required for high filter performance and battery separator materials. Along with this, in recent years, high performance and various functions have been required as filter performance. For the fibers used in filters, various functions are required, such as fibers with an extremely fine denier per filament, fine-denier monofilaments, and fibers with a considerably thick denier, and the required denier, denier per filament, physical properties (strength, shrinkage rate), etc. cover a wide range. And the productivity, dimensional stability, etc. of the fibers have also been emphasized. For example, as a method for obtaining polyphenylene sulfide fibers with good dimensional stability, Patent Document 1 and Patent Document 2 can be cited. Patent Document 1 describes a method for producing polyphenylene sulfide fibers by directly spinning and stretching polyphenylene sulfide fibers under specific stretching conditions to reduce hairiness and yarn breakage. Also, Patent Document 2 describes that by defining the melt flow rate, L / D of the die, cooling method, stretching conditions, etc. and producing by the direct spinning and stretching method, high-quality polyphenylene sulfide fibers with less hairiness and yarn breakage can be produced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the method for producing polyphenylene sulfide fibers disclosed in Patent Document 1, although fibers with a single-filament fineness of 4.4 dtex are specifically described, when the single-filament fineness is further reduced, the number of flyings increases, and it is impossible to obtain fibers with excellent yarn quality. Also, Patent Document 2 specifically describes fibers with a single-filament fineness of 4.5 dtex, but even in this case, when the fineness is further reduced, the number of flyings increases, and it is impossible to obtain fibers with good yarn quality.

[0005] Therefore, an object of the present invention is to solve the above problems and obtain polyphenylene sulfide fibers with high quality, which have good operability in the spinning process and the drawing process, and have few flyings and single-filament breaks even with a fine fineness. Another object of the present invention is to obtain polyphenylene sulfide fibers with good dimensional stability and high quality even if they are polyphenylene sulfide fibers with a fine fineness.

Means for Solving the Problems

[0006] The present inventors have found that by using an oil agent for production with specific oil agent components and specific blending ratios, even with a fine fineness, it is possible to obtain low dry heat polyphenylene sulfide fibers (low dry heat shrinkage fibers) with a reduced number of flyings, high quality, and good dimensional stability. That is, the present invention is first a method for producing polyphenylene sulfide fibers, in which the main structural unit is p-phenylene sulfide, and an oil agent containing 5% to 100% by mass of octyl phosphonate based on the total amount of the oil agent components is adhered so that the amount of oil adhered is 0.3% to 1.5% by mass. Second, the oil agent contains, as an oil agent component, a polyether selected from polyethylene glycol, polypropylene glycol, polybutylene glycol, and a copolymerized polyether obtained by copolymerizing two or more of the above glycols, and is the method for producing polyphenylene sulfide fiber according to 1 above. Third, it is the first or second production method for producing polyphenylene sulfide fiber with a dry heat shrinkage rate at 150 °C of 3.5% or less. Fourth, a polyphenylene sulfide fiber in which an oil agent containing 5% to 100% by mass of octyl phosphonate based on the total amount of the oil agent components is adhered so that the amount of oil adhered is 0.3% to 1.5% by mass, and the main structural unit is a p-phenylene sulfide unit. Fifth, it is a polyphenylene sulfide fiber having a single filament fineness of 3.5 dtex or less and 5 or less hairiness per 1 million m. Sixth, it is the polyphenylene sulfide fiber according to 4 or 5 above having a dry heat shrinkage rate at 150 °C of 3.5% or less.

Advantages of the Invention

[0007] According to the method for producing polyphenylene sulfide fiber of the present invention, by adhering an oil agent with a specific oil agent component and blending ratio at a specific oil adhesion amount, even for fibers with a small single filament fineness, the spinning process and the number of hairiness can be reduced, and high-quality polyphenylene sulfide fiber can be obtained. Furthermore, according to the method for producing polyphenylene sulfide fiber of the present invention, the number of hairiness in fibers with a small single filament fineness can be reduced, and high-quality low dry heat polyphenylene sulfide fiber can be obtained.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, the present invention will be described in detail.

[0009] The polyphenylene sulfide resin used in the present invention is a polyphenylene sulfide consisting of a polymer having a phenylene sulfide unit as a main repeating unit. Examples of the phenylene sulfide unit include a p-phenylene sulfide unit and an m-phenylene sulfide unit. The polyphenylene sulfide may be a homopolymer consisting of a p-phenylene sulfide unit or an m-phenylene sulfide unit, or may be a copolymer having these units, but the repeating unit of p-phenylene sulfide is preferred from the viewpoints of heat resistance, processability, and economy.

[0010] The polymer type of polyphenylene sulfide resin includes a crosslinked type, a semi-crosslinked type, and a linear type, with the linear type being preferred in terms of spinnability and stretchability.

[0011] Furthermore, within the range not impairing the effects of the present invention, the polyphenylene sulfide may contain small amounts of various additives, such as inorganic substances such as various metal oxides, kaolin, and silica, colorants, delustering agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent brightening agents, end group blocking agents, and compatibilizers.

[0012] The melt flow rate (MFR) of the polyphenylene sulfide resin used in the present invention is preferably 100 g / 10 min to 250 g / 10 min. More preferably, it is 130 g / 10 min to 200 g / 10 min. From the viewpoint of spinning stability, it is preferably 100 g / 10 min or more. From the viewpoint of maintaining the strength of the fiber and providing strength and durability to mesh fabrics such as filters for suitable use, it is preferably 250 g / 10 min or less.

[0013] The moisture content of the polyphenylene sulfide resin pellets used in the present invention before spinning is preferably 100 ppm or less, and more preferably 10 ppm to 50 ppm. If it exceeds 100 ppm, it may cause thread breakage during spinning or cause bubbles (air bubbles) to be mixed in, which may reduce the spinning operability.

[0014] The pellets of the polyphenylene sulfide resin used in the present invention are preferably those obtained by vacuum drying as preliminary drying to remove as much as possible low molecular weight components such as moisture and oligomers. The drying temperature is preferably 130°C to 190°C, and the drying time is preferably 6 hours to 12 hours.

[0015] The polyphenylene sulfide fiber of the present invention can be obtained by the production method described below using the above-mentioned polyphenylene sulfide resin.

[0016] The polyphenylene sulfide fiber of the present invention may be a monofilament or a multifilament, but is particularly preferably applicable to multifilaments.

[0017] The fineness of the polyphenylene sulfide fiber of the present invention is preferably 15 dtex to 1,000 dtex, more preferably 33 dtex to 500 dtex.

[0018] The fineness of a single filament of the polyphenylene sulfide fiber of the present invention is preferably 0.8 dtex to 5 dtex, more preferably 1 dtex to 3.5 dtex.

[0019] The number of filaments of the polyphenylene sulfide fiber of the present invention is preferably 12 to 200, more preferably 18 to 150.

[0020] The dry heat shrinkage rate of the polyphenylene sulfide fiber of the present invention at 150°C is preferably 3.5% or less. More preferably, it is 2.5% or less. When the dry heat shrinkage rate is within this range, since the dimensional stability is excellent, it can be particularly preferably used in industrial material fields that require high precision, high heat resistance, and chemical resistance, such as bag filters, motor binding cords, motor binder tapes, and dryer canvases for papermaking.

[0021] The cross-sectional shape of the polyphenylene sulfide fiber of the present invention is not particularly limited, and the outer shape of the fiber may be any shape such as circular, triangular, square, or hollow.

[0022] The polyphenylene sulfide fiber of the present invention preferably has an oil adhesion amount of 0.3% by mass to 1.5% by mass in terms of obtaining a woven fabric, knitted fabric, or mesh with good post-process passing properties and quality. More preferably, it is 0.6% by mass to 1.2% by mass. If it is less than 0.3% by mass, fluff, single-filament breakage, and static electricity are likely to occur during stretching, and the handleability such as weaving tends to be poor. When it exceeds 1.5% by mass, yarn breakage due to yarn shaking during stretching and scum generation during weaving are likely to occur, which may affect the quality of mesh fabrics, industrial filters, etc.

[0023] In the production method of the present invention, even in the case of polyphenylene sulfide fibers with low dry heat resistance, fine-denier polyphenylene sulfide fibers with less fluff can be obtained.

[0024] Hereinafter, polyphenylene sulfide fibers with a dry heat shrinkage rate of 3.5% or less at 150 °C may sometimes be referred to as low dry heat polyphenylene sulfide fibers.

[0025] The oil agent used in the production method of the present invention essentially contains octyl phosphonate described later. It may also contain other oil agent components such as commonly used polyether-based oil agents. Hereinafter, the suitable oil agent used in the production method of the present invention will be described in detail.

[0026] Suitable oil agents used when producing polyphenylene sulfide fibers that require low dry heat resistance (for example, a shrinkage rate of 3.5% or less in the evaluation at 150 °C for 20 minutes) of the present invention include phosphonates (phosphonates). Examples of phosphonates (phosphonates) include hexyl pentyl phosphonate, heptyl pentyl phosphonate, octyl pentyl phosphonate, decyl pentyl phosphonate, phenyl pentyl phosphonate, dibutyl pentyl phosphonate, dihexyl phosphonate, heptyl phosphonate, pentyl phosphonate, octyl phosphonate, and phenyl phosphonate. Among them, potassium octyl phosphonate is preferred.

[0027] The content of the phosphonate in the entire oil agent is preferably 5% by mass to 100% by mass, more preferably 30% by mass to 60% by mass. When it is less than 5% by mass, a good oil film is not formed on the fiber surface, and there is a tendency for it to be easily peeled off. Also, there is a risk of yarn breakage during stretching and single-filament winding around the roll.

[0028] The oil agent for polyphenylene sulfide fibers in the present invention may contain a polyether-based oil agent containing a polyether component such as a single-component polyether such as polyethylene glycol, polypropylene glycol, polybutylene glycol, or a copolymerized polyether obtained by copolymerizing two or more of these polyethers. Among these oil agents, copolymerized polyethers are preferred, and for example, alkyl PO (polypropylene oxide) / EO (ethylene oxide) and the like are preferably mentioned. The polyether component, which is a smoothing component, forms an oil film on the fiber surface. By using a copolymerized polyether, the oil film becomes stronger, and by reducing the damage to the fibers in the inner layer of the package due to winding tightness that occurs during winding, variations in physical properties can be suppressed. In addition, due to the strong oil film, the oil film is less likely to be peeled off by rubbing against various guides, and it is considered that the friction coefficient of the fiber becomes small and the passability in higher-order processes becomes good.

[0029] The average molecular weight of the above polyether component is preferably 2,000 to 13,000, more preferably 3,000 to 10,000. When the average molecular weight is 2,000 or more, a strong oil film can be formed on the fiber surface. When the average molecular weight is 13,000 or less, the viscosity of the oil agent increases as the average molecular weight of the polyether component, which is the oil component, increases, and the friction coefficient on the fiber surface increases. However, it has a tendency not to affect the passability in higher-order processes.

[0030] As the polyether-based oil agent content in the entire oil agent, 4% by mass to 50% by mass is preferable, and more preferably 5% by mass to 30% by mass. When it is less than 4% by mass, a good oil film may not be formed on the fiber surface, it may be easily peeled off, and there is a risk that the passability in the subsequent processes may deteriorate. On the other hand, when it exceeds 50% by mass, the smoothness tends to decrease, and the viscosity of the oil agent may become too high, which may cause defects such as contamination of guides and rollers and dyeing spots on the fabric.

[0031] In addition to the above oil agent, as a smoothing agent, generally used mineral oil for spinning, fatty acid ester, emulsifier, extreme pressure agent, antibacterial agent, etc. may be added.

[0032] In the present invention, as a method of substantially attaching the oil agent to the fiber surface, when attaching, it is preferably used as an aqueous emulsion in which 1% by mass to 25% by mass of the above oil content is dispersed in water with respect to the total amount, and more preferably used as an aqueous emulsion of 5% by mass to 20% by mass. In addition, when using a high-concentration aqueous emulsion with an emulsion concentration exceeding 25% by mass, the physical properties may become unstable when a predetermined oil content is attached. Therefore, in the present invention, it is preferable to attach the oil agent to the fiber surface using a low-concentration aqueous emulsion as described above.

[0033] The breaking strength of the polyphenylene sulfide fiber of the present invention is preferably 4 cN / dtex or more. More preferably, it is 4.5 cN / dtex or more. If it is 4 cN / dtex or more, even when used for fabrics, etc., the fabric strength will be sufficient.

[0034] The elongation at break of the polyphenylene sulfide fiber of the present invention is preferably 18% to 28%. More preferably, it is 20% to 25%. When it is less than 18%, there is a risk that the spinning operability may deteriorate due to the generation of fuzz during fiber production, and there is also a risk that the quality of the fabric using this fiber may deteriorate. When it exceeds 28%, the dimensional stability of the fabric using this fiber tends to deteriorate, and there is also a risk that the quality of the fabric using this fiber may deteriorate.

[0035] The dry heat shrinkage rate of the polyphenylene sulfide fiber of the present invention at 150 °C is preferably 3.5% or less. More preferably, it is 2.5% or less. When it exceeds 3.5%, the fabric using this fiber tends to have poor dimensional stability, and there is a risk that the quality of the fabric using this fiber will deteriorate.

[0036] The polyphenylene sulfide fiber of the present invention may, if necessary, be interlaced using an interlace nozzle (I / L) after passing through the draw roll. In this case, the number of interlaces is preferably 8 to 25 per meter, more preferably 10 to 20 per meter.

[0037] As for the number of flyings of the polyphenylene sulfide fiber of the present invention, when the single fiber fineness is 3.5 dtex or less, the number of flyings per 1 million meters is preferably 5 or less. More preferably, it is less than 2, and even more preferably, there are no flyings (the number of flyings is 0). When the number of flyings exceeds 5, the defects of the fabric using this fiber increase, and it becomes a fabric with many unusable fabric parts (so-called C-reverse), making it difficult to use for products such as filters that require high precision and performance.

[0038] A preferred production method of the polyphenylene sulfide fiber of the present invention will be described in detail below.

[0039] For the production of the polyphenylene sulfide fiber in the present invention, it is preferably produced by a conventional method. Specifically, as the first step, an undrawn yarn bobbin of polyphenylene sulfide fiber obtained by melt spinning a polyphenylene sulfide resin is collected by a spinning machine, and then, as the second step, an undrawn yarn is drawn from the obtained undrawn yarn bobbin and drawn and heat set by a drawing machine to obtain a drawn yarn.

[0040] Hereinafter, a more specific and preferred production method will be described.

[0041] First, using an extruder-type spinning machine, melt polyphenylene sulfide resin pellets and perform melt spinning. The spinning temperature during melt spinning is preferably 300°C to 330°C.

[0042] After melting the resin pellets, filter the molten resin with a spinning filter, and then discharge and extrude it through a nozzle hole using a spinning nozzle.

[0043] Regarding the clearance of the above-mentioned spinning filter, from the viewpoints of contaminant and gel removal and fluff reduction, for those below 40 dtex, 5 μm to 15 μm is preferable, and for those exceeding 40 dtex, 15 μm to 30 μm is preferable.

[0044] After extruding the molten resin from the nozzle hole, the extruded yarn passes through a heat preservation cylinder and a cooling zone installed directly below the spinning. By blowing cold air in this cooling zone, the extruded resin solidifies.

[0045] The temperature of the above-mentioned cold air is preferably in the range of 20°C to 30°C. The wind speed of the cold air is usually preferably in the range of 20 m / min to 45 m / min. However, in the case of a fine single fiber fineness with a single fiber fineness of 1.5 dtex or less after drawing, the range of 20 m / min to 30 m / min is preferable.

[0046] Also, as the cooling zone, it is preferably started from directly below the die, about 80 mm to 150 mm.

[0047] After the extruded yarn is cooled and solidified, an oil agent is applied. Incidentally, it is preferable to apply the oil agent after passing through the cooling zone. As the application method, it may be appropriately performed by a known application method such as roll application or guide application.

[0048] After applying the oil agent, pass the yarn through a godet roll, wind it at a predetermined spinning speed, and obtain an undrawn bobbin of polyphenylene sulfide fiber.

[0049] The spinning speed is preferably in the range of 800 m / min to 1600 m / min.

[0050] Next, the obtained polyphenylene sulfide undrawn yarn is drawn. In the case of multifilaments that require low dry heat characteristics, as the drawing device, it is preferably composed of a pair of feed rolls (1stR) that form a pair with a rubber roll, a roll heater (2ndR) for preheating, a plurality of roll heaters (3rdR, 4thR) for heat setting, and a draw roll (5thR), and a device that is wound into a yarn shape by spindle drive is used.

[0051] In this case, the temperature of the roll heater of 2ndR is preferably 100°C to 120°C, more preferably 105°C to 110°C.

[0052] The heat setting temperature of 3rdR and 4thR may be appropriately set according to the intended use. For example, the heat setting temperature of 3rdR is preferably in the range of 100°C to 160°C, and the heat setting temperature of 4thR is preferably in the range of 180°C to 225°C.

[0053] Also, the drawing speed is preferably 500 m / min to 1,200 m / min, more preferably 600 m / min to 1,000 m / min.

[0054] The draw ratio is preferably in the range of 1.01 times to 1.05 times between 1stR and 2ndR, more preferably 1.01 times to 1.03 times. Between 3rdR and 4thR, 1 time to 1.1 times is preferred. Between 4thR and 5thR, it is preferably mainly for relaxation treatment, and in this case, it is preferably 0.95 times to 0.99 times, more preferably 0.965 times to 0.985 times. Between 2ndR and 3rdR, the draw ratio may be adjusted and set according to the target elongation of the fiber (for example, 23%). Also, a suitable total draw ratio is in the range of 2 times to 4.5 times, although it also depends on the spinning winding speed.

Example

[0055] The present invention will be specifically described below with reference to examples. It should be noted that the present invention is not limited to the examples described below. The physical properties and evaluations of the filaments in the examples were as follows. A. MFR In accordance with JIS K 7210 (1999), the MFR value was measured under the conditions of a temperature of 315.5 °C and a load of 5000 g. B. Fineness In accordance with JIS L 1013 (2010), using a measuring machine with a frame circumference of 1.125 m, the sample was wound up at a speed of 120 revolutions per minute, its mass was weighed, and the fineness was determined. This was measured 5 times, and the average value was taken as the fineness. C. Tensile strength, elongation at break In accordance with JIS L 1013 (2010), using an AGS-1KNG autograph (registered trademark) tensile testing machine manufactured by Shimadzu Corporation, the measurement was carried out under the conditions of a sample yarn length of 20 cm and a constant speed tensile rate of 20 cm / min. The value obtained by dividing the maximum value of the load in the load-elongation curve by the fineness was taken as the tensile strength (cN / dtex), and the elongation rate at that time was taken as the elongation at break (%). D. Dry heat shrinkage rate at 150 °C It was measured using a dryer heated to 150 °C by the method of JIS L 1013 (2010) 8.18.2b. E. Hairiness evaluation The drawn yarn was placed on a creel, tension was applied to the yarn with a ring tenser, the yarn was passed through a laser type detector, and measurement was carried out at a measurement speed of 400 m / min. Measurement was carried out for 100,000 m per strand and converted to per 1,000,000 m for calculation. Next, 10 strands were measured, the average value was calculated, and the number of hairiness per 1,000,000 m was taken. F. Oil adhesion amount 2 g of fiber was collected by a measuring machine (A), the sizing agent adhering to it was extracted with methanol, the methanol was volatilized, the amount of the remaining residue (sizing agent) (B) was weighed, and the oil adhesion amount (mass %) was determined using the following formula 1. Oil adhesion amount (mass %) = B / A × 100 (Formula 1) G. Entanglement number A 1-m sample was cut out in the fiber longitudinal direction, the fiber was immersed in a bucket filled with water, and the number of entangled portions was counted. The operation was carried out N = 3 times, and the average value was taken as the entanglement number. H. Spinning operability When it was impossible to collect the bobbin, impossible to wind, or the yarn was cut immediately below the nozzle when the yarn was sucked by the air sac, it was marked as "×". When single-yarn winding occurred on the godet roller, it was marked as "△". When the undrawn yarn bobbin could be collected without these troubles, it was marked as "〇". I. Draw-twist operability When yarn breakage occurred, it was marked as "×". When single-yarn winding occurred on the draw roller, it was marked as "△". When the drawn yarn could be collected without these troubles, it was marked as "○". J. Comprehensive evaluation In the above-mentioned H. Spinning operability and I. Draw-twist operability, if there is even one "×", it is marked as "×". If there is even one "△" except for "×", it is marked as "△". If all are "○" and the number of hairiness per 1 million m is 5 or less, it is marked as "○".

[0056] 〔Example 1〕 A polyphenylene sulfide resin with an MFR of 160 g / 10 min (moisture content: 20 ppm) was prepared and melted at a spinning temperature of 328°C. The molten polyphenylene sulfide was extruded at an extrusion rate such that the undrawn fineness was 850 dtex using a spinneret for spinning having 72 holes (L / D = 0.5 mm / 0.23 mm). The extruded polyphenylene sulfide filaments were cooled with cold air at 25°C using a uniflow type cooling device. Thereafter, the filaments were adjusted to 18% by mass of an emulsion oil agent in which 5% by mass of a copolymerized polyether component (alkyl PO / EO) (hereinafter sometimes referred to as Co-POE) and 25% by mass of potassium octyl phosphonate (hereinafter sometimes referred to as Oct-P) were added with 70% by mass of a smoothing agent of a fatty acid ester and a nonionic emulsifier main component as other oil agent components (Other), and the emulsion oil agent was applied with an oiling nozzle (OPU: 1% by mass). Then, the filaments were passed through two non-heated godet rolls at a speed of 1,550 / min, and the bobbin was wound with a winder to obtain an undrawn bobbin of polyphenylene sulfide fiber. In the next drawing step, a drawing device composed of a creel, a non-heated feed roll (1stR), a heater roll for preheating (2ndR), two heater rolls for heat setting (3rdR, 4thR), a draw roll (5thR), and a winding section was used. The undrawn bobbin was installed on the creel, preheated at 2ndR (100°C), heat set at 3rdR (110°C) and 4thR (220°C), and drawn at a draw ratio (DR) between 1st - 2ndR × DR between 2nd - 3rdR × DR between 3rd - 4thR × DR between 4th - 5thR = 1.03 × 3.38 × 1.00 × 0.978, and wound at a drawing speed of 800 m / min to obtain low dry heat polyphenylene sulfide fibers.

[0057] 〔Example 2〕 Low dry heat polyphenylene sulfide fibers were obtained in the same manner as in Example 1, except that the ratio of the oil agent components was changed to an oil agent of Co-POE:Oct-P:Other = 5% by mass:50% by mass:45% by mass.

[0058] 〔Example 3〕 Except for changing the oil agent composition ratio to Co-POE: Oct-P: Other = 0 mass%: 50 mass%: 50 mass%, low dry heat polyphenylene sulfide fibers were obtained in the same manner as in Example 1.

[0059] [Comparative Example 1] Except for changing the oil agent composition ratio to Co-POE: Oct-P: Other = 5 mass%: 0 mass%: 95 mass%, low dry heat polyphenylene sulfide fibers were obtained in the same manner as in Example 1.

[0060] [Comparative Example 2] Except for changing the oil agent composition ratio to Co-POE: Oct-P: Other = 20 mass%: 3 mass%: 77 mass%, low dry heat polyphenylene sulfide fibers were obtained in the same manner as in Example 1.

[0061] [Comparative Example 3] Except for changing the oil agent composition ratio to Co-POE: Oct-P: Other = 0 mass%: 0 mass%: 100 mass%, low dry heat polyphenylene sulfide fibers were obtained in the same manner as in Example 1.

[0062] [Example 4] Except for changing the oil agent composition ratio to Co-POE: Oct-P: Other = 0 mass%: 100 mass%: 0 mass%, low dry heat polyphenylene sulfide fibers were obtained in the same manner as in Example 1.

[0063] [Example 5] Except for changing the oil agent composition ratio to Co-POE: Oct-P: Other = 25 mass%: 25 mass%: 50 mass%, low dry heat polyphenylene sulfide fibers were obtained in the same manner as in Example 1.

[0064] [Example 6] Except for changing the oil agent composition ratio to Co-POE: Oct-P: Other = 45 mass%: 25 mass%: 30 mass%, low dry heat polyphenylene sulfide fibers were obtained in the same manner as in Example 1.

[0065] [Example 7] Except for changing the oil agent composition ratio to Co-POE: Oct-P: Other = 60% by mass: 25% by mass: 15% by mass, low dry-heat polyphenylene sulfide fibers were obtained in the same manner as in Example 1.

[0066] 〔Examples 8, 9, Comparative Examples 4, 5〕 Except for changing the amount of oil adhered, low dry-heat polyphenylene sulfide fibers were obtained in the same manner as in Example 2.

[0067] 〔Example 10〕 Except for using a spinneret having 72 holes for spinning (L / D = 0.4 mm / 0.2 mm) and adjusting the discharge amount so that the undrawn fineness becomes 410 dtex, low dry-heat polyphenylene sulfide fibers were obtained in the same manner as in Example 2.

[0068] 〔Example 11〕 Except for using a spinneret having 72 holes for spinning (L / D = 0.35 mm / 0.18 mm) and adjusting the discharge amount so that the undrawn fineness becomes 286 dtex, low dry-heat polyphenylene sulfide fibers were obtained in the same manner as in Example 2.

[0069] 〔Comparative Example 6〕 Except for changing the oil agent composition ratio to Co-POE: Oct-P: Other = 5% by mass: 0% by mass: 95% by mass, low dry-heat polyphenylene sulfide fibers were obtained in the same manner as in Example 11.

[0070] The oil agent conditions, yarn physical properties, and the results of each evaluation of the low dry-heat polyphenylene sulfide fibers of Examples 1 to 11 and Comparative Examples 1 to 6 are shown in Table 1.

[0071]

Table 1

[0072] The low dry heat polyphenylene sulfide fibers obtained from Examples 1 to 11 had good spinning operability and drawing and twisting operability, few flyings in the fibers, a low dry heat shrinkage rate, excellent dimensional stability, and excellent strength and elongation characteristics, resulting in high-quality fibers. These fibers also had extremely excellent passability in subsequent processes, enabling the production of high-quality products. Among them, products using the fibers obtained from Examples 2 to 4 and 8 to 11, with potassium octyl sulfonate as the main component of the oil agent component, were particularly excellent. The polyphenylene sulfide fibers obtained from Comparative Examples 1, 3, and 6, which did not contain potassium octyl phosphonate in the oil agent component, had a considerable number of single-filament windings on the draw rolls during the stretching process, and single-filament breaks and flyings were scattered on the surface and end faces of the wound bobbins. Also, an average of 8.2 (Comparative Example 1) and 28 (Comparative Example 6) flyings per million meters were detected in the evaluation of the number of flyings, indicating that the fibers had very poor quality and poor drawing and twisting operability. The polyphenylene sulfide fibers obtained from Comparative Example 2, which contained only 3% by mass of potassium octyl phosphonate in the oil agent component, showed a slightly better situation than Comparative Example 1, but the same phenomenon was confirmed, and the obtained fibers had very poor quality and poor drawing and twisting operability. The polyphenylene sulfide fibers obtained from Comparative Example 3, which did not contain both potassium octyl phosphonate and copolymerized polyether in the oil agent component, had worse fiber quality than Comparative Example 1, with frequent flyings and an average of 35 flyings per million meters detected, indicating very poor fiber quality and poor drawing and twisting operability. The polyphenylene sulfide fibers obtained from Comparative Example 4, with a small amount of oil and fat adhering to the fibers, had single-filament breaks due to yarn shaking on the godet roll during spinning and yarn shaking on each roll during the stretching process, resulting in many flyings and poor quality. The polyphenylene sulfide fibers obtained from Comparative Example 5, with a large amount of oil and fat adhering to the fibers, had single-filament breaks due to yarn shaking on the roller during the stretching process in spinning, resulting in many flyings and poor quality.

[0073] Thus, the polyphenylene sulfide fibers (low dry heat yarns) obtained from Examples 1 to 11 were fibers with good spinning and twisting operability, reduced fiber hairiness, and good quality by selecting specific lubricants and blending amounts. Also, the subsequent passing properties in post-processes such as warping, weaving, and processing were very good, resulting in high-quality fabrics and products.

Claims

1. A method for producing polyphenylene sulfide fibers, wherein the main structural unit is p-phenylene sulfide, comprising adhering an oil agent containing 5% by mass to 100% by mass of octyl phosphonate based on the total amount of the oil agent components so that the amount of adhered oil and fat is 0.3% by mass to 1.5% by mass.

2. The method for producing polyphenylene sulfide fibers according to claim 1, wherein the oil agent contains, as an oil agent component, a polyether selected from polyethylene glycol, polypropylene glycol, polybutylene glycol, and a copolymerized polyether obtained by copolymerizing two or more of the above glycols.

3. The production method according to claim 1 or 2, for producing polyphenylene sulfide fibers having a dry heat shrinkage rate at 150 °C of 3.5% or less.

4. Polyphenylene sulfide fibers, wherein the main structural unit is a p-phenylene sulfide unit, to which an oil agent containing 5% to 100% by mass of octyl phosphonate based on the total amount of the oil agent components is adhered so that the amount of adhered oil and fat is 0.3% by mass to 1.5% by mass.

5. Polyphenylene sulfide fibers having a single filament fineness of 3.5 dtex or less and a number of fiber ends per 1,000,000 m of 5 or less.

6. The polyphenylene sulfide fibers according to claim 4 or 5, having a dry heat shrinkage rate at 150 °C of 3.5% or less.

Images