Method for producing polyphenylene sulfide fibers

Abstract

To provide high-grade polyphenylene sulfide fibers that can be efficiently obtained with good operability in spinning and drawing processes and have low fluff and single thread breakage.SOLUTION: Provided is a method for producing polyphenylene sulfide fibers whose main constituent unit is a p-phenylene sulfide unit and which are spun using a mouthpiece with L / D of 0.8 to 4, a ratio being of a land length (L) of a nozzle hole portion of the mouthpiece to a diameter (D) of the nozzle hole, while satisfying a relation between a spinning draft of the nozzle hole portion of the mouthpiece and a shear rate that is any one of requirements (1) to (5): (1) shear rate 85,000 to 140,000 when spinning draft is 5 or more and less than 7.5, (2) shear rate 60,000 to 100,000 when spinning draft is 7.5 or more and less than 9.5, (3) shear rate 45,000 to 80,000 when spinning draft is 9.5 or more and less than 14, (4) shear rate 20,000 to 60,000 when spinning draft is 14 or more and less than 18, and (5) shear rate 5,000 to 40,000 when spinning draft is 18 or more and less than 180.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In industrial filters, mesh fabrics made of polyphenylene sulfide, polyvinylidene fluoride, liquid crystal polyester, etc. are currently widely used in terms of chemical resistance, dimensional stability, heat durability, etc. In particular, mesh fabrics made of polyphenylene sulfide are widely used because they are excellent in chemical resistance, dimensional stability, and cost performance, and are suitable for fields where high filter performance is required. Furthermore, in recent years, due to the high performance of filters, the required fineness, single yarn fineness, physical properties (strength, shrinkage rate), etc., are diverse, such as extremely fine single yarn fineness, thin monofilament, and quite thick fiber. Accordingly, the productivity and uniformity of fibers are also important. Patent Document 1 describes a manufacturing method in which polyphenylene sulfide fibers having high strength, high elongation and high thermal dimensional stability are stretched by a direct spinning stretching method, mainly in the stretching step, to reduce fuzz and yarn breakage. Furthermore, Patent Document 2 describes a production method in which polyphenylene sulfide fiber having high strength, high elongation, and high thermal dimensional stability is stretched by a direct spinning-stretching method, in which the melt flow rate, L / D of the spinneret, cooling method, stretching conditions, etc. are specified to reduce fuzz and yarn breakage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4962361 [Patent Document 2] JP 2001-262436 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the method for producing polyphenylene sulfide fiber in Patent Document 1, specifically, the yarn is entangled at 5 to 20 pieces / m using interlacing and then bundled, and the yarn has a fuzz count of more than 20 pieces per 10 million km, and the yarn quality is not excellent. Patent Document 2 describes that the L / D ratio specified in the method for producing polyphenylene sulfide fiber is preferably 2.5 to 8, but if the L / D ratio is too high, the back pressure at the nozzle hole becomes too high, causing the back pressure in the pack to increase, resulting in problems such as failure to spin or failure to spin for long periods of time. In addition, there is a risk that the clearance of the filter for removing gels and contaminants cannot be made fine. In addition, an aqueous emulsion containing a smoothing agent, an activator, an emulsifier, etc. as the main components is used as the spinning oil, but there is no description of the inclusion of an antistatic agent such as polyethers or phosphonates, and this is insufficient as a measure to reduce fluff.

[0005] Therefore, an object of the present invention is to solve the above problems, and to provide a high-quality polyphenylene sulfide fiber which has good operability in the spinning and drawing steps, can produce fibers efficiently, and has little fuzz or single-fiber breakage. [Means for solving the problem]

[0006] The present inventors have found that in polyphenylene sulfide fibers, by setting the spinning draft and shear rate at a specific L / D of the spinning nozzle hole, it is possible to reduce the number of fuzz contained in the fibers, thereby obtaining high-quality fibers. That is, first, the present invention provides a method for producing a polyphenylene sulfide fiber whose main constituent unit is a p-phenylene sulfide unit, wherein the relationship between the spinning draft of the spinneret nozzle hole and the shear rate satisfies any one of conditions (1) to (5), and spinning is performed using a spinneret having a ratio L / D, which is the ratio of the land length (L) of the spinneret nozzle hole to the diameter (D) of the nozzle hole, of 0.8 to 4. (1) When the spinning draft is 5 or more and less than 7.5, the shear rate is 85,000 to 140,000 (2) When the spinning draft is 7.5 or more and less than 9.5, the shear rate is 60,000 to 100,000 (3) When the spinning draft is 9.5 or more and less than 14, the shear rate is 45,000 to 80,000 (4) When the spinning draft is 14 or more but less than 18, the shear rate is 20,000 to 60,000 (5) When the spinning draft is 18 or more but less than 180, the shear rate is 5,000 to 40,000 A second aspect of the present invention is a method for producing the above-mentioned polyphenylene sulfide fiber, characterized in that the spinning oil contains, as a component, a single-component polyether selected from polyethylene glycol, polypropylene glycol, and polybutylene glycol, or a copolymer polyether obtained by copolymerizing two or more of them. A third aspect of the present invention is a method for producing the above-mentioned low dry heat polyphenylene sulfide fiber, characterized in that the spinning oil contains an octylphosphonate salt. A fourth aspect of the present invention is a polyphenylene sulfide fiber having a single fiber fineness of 4 dtex or more and a fluff count of 2 or less per 1 million meters. A fifth aspect of the present invention is a polyphenylene sulfide fiber having a single yarn fineness of more than 2 dtex and less than 4 dtex and a fuzz count of 5 or less per 1,000,000 meters. A sixth aspect of the present invention is a polyphenylene sulfide fiber having a single fiber fineness of 2 dtex or less and a fluff count of 8 or less per 1,000,000 meters. Effect of the Invention

[0007] According to the polyphenylene sulfide fiber of the present invention, by specifying the spinning draft and shear rate of the L / D of the spinning nozzle hole, it is possible to greatly improve the spinning and drawing operability, reduce fuzz in the fiber, and improve the fiber quality. [Brief description of the drawings]

[0008] [Figure 1] 1 is an example of a graph showing the relationship between spinning draft and shear rate in the fiber production method of the present invention. [Diagram 2] 4 is another example of a graph showing the relationship between the spinning draft and the shear rate in the fiber production method of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described in detail below.

[0010] In the present invention, the method for producing the polyphenylene sulfide fiber is, for example, a conventional method in which a resin is melted using a spinning machine, the molten resin is filtered through a filter, and then spun through a spinning nozzle and a nozzle hole of a die, after which the yarn is cooled and solidified in a cooling zone, wound at a predetermined spinning speed, an undrawn yarn bobbin is collected, and drawn and heat-set in a drawing machine to produce a drawn yarn.

[0011] The polyphenylene sulfide resin in the present invention is a polyphenylene sulfide composed of a polymer having a p-phenylene sulfide unit as a main repeating unit (structural unit).

[0012] Polyphenylene sulfide polymer types include crosslinked types, semi-crosslinked types, and linear types, with the linear type being preferred in terms of spinnability and stretchability.

[0013] 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.

[0014] The melt flow rate (MFR) of the polyphenylene sulfide resin in the present invention is preferably 100 to 250 g / 10 min. More preferably, it is 130 to 200 g / 10 min. From the viewpoint of easy spinning, it is preferably 100 g / 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 / min or less.

[0015] The moisture content of the polyphenylene sulfide resin pellets before spinning in the present invention is preferably 100 ppm or less, more preferably 10 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.

[0016] The polyphenylene sulfide resin pellets in the present invention are preferably pre-dried by vacuum drying to remove low molecular weight components as much as possible, and the drying temperature is preferably 130 to 190° C. and the drying time is preferably 6 to 12 hours.

[0017] The melting of the polyphenylene sulfide resin pellets of the present invention is preferably performed using an extruder type spinning machine. The spinning temperature is set to 300 to 330°C, and the clearance of the spinning filter is preferably 5 to 15 μm for 40 dtex or less, and 15 to 30 μm for those exceeding 40 dtex, from the viewpoint of removing contamination and gel and reducing fuzz. After melting the resin, it is filtered through a filter, and then spun from the nozzle hole using a spinning nozzle.

[0018] The spinning draft at the nozzle hole of the spinneret used in the present invention is expressed as the ratio of the spinning speed to the linear discharge speed at the nozzle hole of the spinneret. The shear rate (γ) at the nozzle hole of the spinneret is expressed as r (cm) for the average nozzle radius and Q (cm) for the polymer discharge amount per hole. 3 / sec), then γ = 4Q / πr 3It is calculated by the formula: The spinning draft and shear rate are preferably selected by appropriately selecting the land length (L) and hole diameter (D) of the nozzle hole according to the fineness and number of filaments, so as to obtain the following spinning draft and shear rate. When the spinning draft is 5 or more and less than 7.5, the shear rate is 85,000 to 140,000, when the spinning draft is 7.5 or more and less than 9.5, the shear rate is 60,000 to 100,000, when the spinning draft is 9.5 or more and less than 14, the shear rate is 45,000 to 80,000, when the spinning draft is 14 or more and less than 18, the shear rate is 20,000 to 60,000, and when the spinning draft is 18 or more and less than 180, the shear rate is 5,000 to 40,000. When the shear rate is below the lower limit, the back pressure at the nozzle hole becomes low, the polymer flow becomes unstable, and spinning failure occurs such as yarn unevenness and frequent yarn breakage directly below the nozzle during winding and winding. When the shear rate exceeds the upper limit, the back pressure at the nozzle hole becomes too high, so the back pressure in the pack becomes high, making spinning impossible or making it impossible to spin for a long time. In addition, there is a risk that the clearance of the filter for removing gels and contaminants cannot be made fine. 1 and 2 are examples of plots of shear rate and spinning draft. Black dots (◆) are within the scope of the examples of the present invention, and white dots (◇) are outside the scope of the present invention.

[0019] In the present invention, the ratio of the land length (L) of the nozzle hole of the spinneret nozzle part to the diameter (D) of the nozzle hole is preferably 0.8 or more and 4 or less, more preferably 1.5 to 2.3. If L / D is less than 0.8, the back pressure becomes unstable, which may cause unevenness of the yarn or impair spinnability. If L / D is 2.5 or more, the pressure loss at the land part becomes large, the back pressure becomes too high, and spinning becomes impossible or it becomes difficult to strengthen the filtration of the spinning filter, which may cause an increase in the number of fluffs in the produced fiber.

[0020] In the present invention, the polymer discharged from the nozzle passes through a heat-retaining tube and a cooling zone immediately below the spinning, and is solidified by blowing cold air onto it. The temperature of the cold air at this time is preferably 20 to 30°C. The speed of the cold air is preferably 20 to 45 m / min. When the single yarn fineness after drawing is 1.5 dtex or less, the speed of the cold air is more preferably 20 to 30 m / min. In addition, the cooling zone is preferably 100 mm or less directly below the spinneret.

[0021] In the method of applying an oil according to the present invention, a spinning oil is applied after passing through the cooling zone. As a method for applying the oil, a known method can be used, such as applying the oil by contacting with a roll or by contacting with a guide.

[0022] In terms of the ability of the polyphenylene sulfide fiber in the present invention to pass through subsequent processes and to obtain woven fabrics, knitted fabrics, and meshes of good quality, the thread oil adhesion amount (OPU) is preferably 0.15 to 0.5 mass% in the case of monofilament. More preferably, it is 0.25 to 0.35 mass%. If it is less than 0.15 mass%, static electricity tends to be easily generated and handling properties such as weaving tend to be poor. If it exceeds 0.5 mass%, scum tends to be easily generated during weaving, which may affect the quality of mesh woven fabrics and industrial filters, and may cause bobbin collapse during the spinning and winding process. In addition, in the case of multifilament, it is preferably 0.5 to 1.5 mass%. More preferably, it is 0.6 to 1.2 mass%. If it is less than 0.5 mass%, static electricity tends to be easily generated and handling properties such as during weaving tend to be poor. If the content exceeds 1.5% by mass, scum tends to be generated during weaving, which may affect the quality of mesh fabrics, industrial filters, etc.

[0023] The spinning oil for the polyphenylene sulfide fiber in the present invention preferably contains a polyether component consisting of a single component polyether such as polyethylene glycol, polypropylene glycol, or polybutylene glycol, which is an antistatic agent, or a copolymer polyether obtained by copolymerizing two or more of these polyethers. Among these oils, copolymer polyethers are preferred, such as alkyl PO / EO. The polyether component, which is a smoothing component, forms an oil film on the fiber surface, and the use of copolymer polyether makes the oil film stronger, reducing damage to the fiber in the inner layer of the package caused by tight winding during winding, thereby suppressing variations in physical properties. In addition, the strong oil film makes the oil film less likely to peel off when rubbed against various guides, and it is thought that the friction coefficient of the fiber is reduced, improving the passability through higher-level processes.

[0024] The average molecular weight of the polyether component is preferably 2000 to 13000, and more preferably 3000 to 10000. When the average molecular weight is 2000 or more, a strong oil film can be formed on the fiber surface, and when the average molecular weight is 13000 or less, the viscosity of the spinning oil increases with an increase in the average molecular weight of the polyether component, which is an oil, and the friction coefficient of the fiber surface increases, but this does not tend to affect the passability through higher-order processes.

[0025] The content of the polyether-based antistatic agent in the spinning oil is preferably 4 to 50%, more preferably 5 to 30%. If it is less than 4%, a good oil film is not formed on the fiber surface, which may cause the fiber to peel off easily and may cause poor passability through higher-level processes. If it exceeds 50%, the smoothness may be lost and the viscosity of the spinning oil may become too high, which may cause defects such as contamination of guides and rollers and dyeing spots on the fabric.

[0026] In addition to the above-mentioned antistatic agent, a mineral oil, a fatty acid ester, or an emulsifier that is generally used for spinning may be added as a smoothing agent.

[0027] In the present invention, in the polyphenylene sulfide fiber having low dry heat properties (shrinkage rate of 3.5% or less when evaluated at 150°C for 20 minutes), the spinning oil preferably contains a phosphonate (phosphonate salt) which is an antistatic agent. Specific examples 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 particularly preferred. As the smoothing agent, fatty acid esters are preferable, and any type is acceptable. An emulsifier may be used in combination. Polyethers may also be used.

[0028] The content of the phosphonate-based oil, which is an antistatic agent contained in the spinning oil, is preferably 10 to 100% by mass, and more preferably 30 to 60% by mass, when the total composition of the oil is taken as 100% by mass. If it is less than the lower limit, a good oil film is not formed on the fiber surface, which may cause the fiber to peel off easily, or the fiber may break during drawing or the single fiber may be wound around the roll.

[0029] In the present invention, as a method for substantially adhering the spinning oil to the fiber surface, it is preferable to use an aqueous emulsion in which the oil is dispersed in water at 1% by mass to 20% by mass relative to the total amount, and an aqueous emulsion of 1% by mass to 20% by mass is more preferable. If an aqueous emulsion with a high emulsion concentration exceeding 20% ​​by mass is used, the physical properties may become unstable when a certain oil is adhered, so such an aqueous emulsion with a low concentration is preferable.

[0030] In the winding process of the present invention, after the yarn is oiled, the undrawn yarn is wound through a godet roll at a predetermined spinning speed, preferably 400 to 3600 m / min.

[0031] A suitable drawing machine used for drawing the polyphenylene sulfide undrawn yarn of the present invention, which is a multifilament that does not require low dry heat properties, is, for example, a drawing machine that is composed of a feed roll (1stR) paired with a rubber roller, a roll heater (2ndR) for preheating, a draw roll (3rdR), and a plate heater between the roll heater and the draw roll, and in which the pirn is wound up by spindle drive. The temperature of the roll heater is preferably from 100 to 120°C, and more preferably from 105 to 110°C. The heat set temperature of the plate heater is preferably 160 to 190° C., taking into consideration use for various industrial filters and the like. The stretching speed is preferably from 500 to 1200 m / min, and more preferably from 600 to 1000 m / min. The draw ratio is preferably 1.01 to 1.05 times between the 1stR and the 2ndR, and more preferably 1.01 to 1.03 times. Between the 2ndR and the 3rdR, the draw ratio may be adjusted to set the target elongation of the fiber to, for example, 30%.

[0032] A suitable drawing machine for use in drawing monofilament that does not require the above-mentioned low dry heat properties in the polyphenylene sulfide undrawn yarn of the present invention is one that is composed of a feed roll (1stR) paired with a rubber roller, a roll heater (2ndR) for preheating, a cold roll (3rdR), a draw roll (4thR), and a plate heater between the cold roll and the draw roll, and that winds up the pirn by spindle drive. The temperature of the roll heater is preferably from 100 to 120°C, and more preferably from 105 to 110°C. The heat setting temperature is preferably 160 to 190° C., taking into consideration use in various industrial filters and the like. The stretching speed is preferably from 500 to 1200 m / min, and more preferably from 600 to 1000 m / min. The draw ratio is preferably 1.01 to 1.05 times between the 1stR and the 2ndR, and more preferably 1.01 to 1.03 times. Between the 3rdR and the 4thR, a relaxation treatment is performed mainly to reduce the occurrence of piercing sink marks, and therefore the draw ratio is preferably 0.95 to 0.99 times, and more preferably 0.965 to 0.985 times. Between the 2ndR and the 3rdR, the draw ratio may be adjusted to set the target elongation of the fiber to, for example, 30%.

[0033] A suitable drawing machine for use in drawing the polyphenylene sulfide undrawn yarn of the present invention, which is a multifilament that requires the above-mentioned low dry heat properties, is one that is composed of a feed roll (1stR) paired with a rubber roller, a roll heater (2ndR) for preheating, roll heaters (3rdR, 4thR) for heat setting, and a draw roll (5thR), and is a type in which the yarn is wound up by spindle drive. The temperature of the roll heater is preferably from 100 to 120°C, and more preferably from 105 to 110°C. Considering that the 3rd and 4thR are used for various industrial materials, the heat setting temperatures are preferably 100 to 160°C for 3rdR and 180 to 225°C for 4t-hR. The stretching speed is preferably from 500 to 1200 m / min, and more preferably from 600 to 1000 m / min. The draw ratio is preferably 1.01 to 1.05 times between 1stR and 2ndR, and more preferably 1.01 to 1.03 times. Between 3rdR and 4thR, it is preferably 1 to 1.1 times. Between 4thR and 5thR, it is preferably 0.95 to 0.99 times, and more preferably 0.965 to 0.985 times, since relaxation treatment is mainly performed therebetween. Between 2ndR and 3rdR, the draw ratio may be adjusted to set the target elongation of the fiber to, for example, 23%.

[0034] For the polyphenylene sulfide multifilament of the present invention, if necessary, an interlace nozzle (I / L) may be introduced after passing through the draw roll to entangle the yarn. In this case, the number of entanglements is preferably in the range of 8 to 25 / m, more preferably 10 to 20 / m.

[0035] The number of fluffs of the polyphenylene sulfide fiber in the present invention is preferably 2 or less fluffs per 1 million meters when the single yarn fineness is 4 dtex or more, 5 or less fluffs per 1 million meters when the single yarn fineness is more than 2 dtex and less than 4 dtex, and 8 or less fluffs per 1 million meters when the single yarn fineness is 2 dtex or less. More preferably, the number of fluffs per 1 million meters is less than 2 at each single yarn fineness, and most preferably, there is no fluff. If the number of fluffs is within the above range, the fabric defects are reduced compared to conventional products, and the fiber can be particularly suitably used for products such as filters that require high precision and high performance.

[0036] The cross-sectional shape of the polyphenylene sulfide fiber in the present invention is not particularly limited, and the outer shape of the fiber may be any shape such as circular, triangular, rectangular, hollow, etc. EXAMPLES

[0037] The present invention will be specifically described below with reference to examples. Note that the present invention is not limited to the examples described below. The physical properties and evaluation of the filaments in the examples are as follows. A.MFR The MFR value was measured at a temperature of 315.5°C and a load of 5000g in accordance with JIS K 7210 (2014). B. Fineness In accordance with JIS L 1013, the sample was wound at a speed of 120 times / min using a measuring machine with a frame circumference of 1.125 m, and the mass was measured to determine the fineness. This measurement was repeated five times, and the average value was calculated. C. Breaking strength, breaking elongation Measurements are made using a Shimadzu AGS-1KNG autograph tensile tester with a sample length of 20 cm and a constant tensile speed of 20 cm / min in accordance with JIS L 1013. The breaking strength (cN / dtex) is calculated by dividing the maximum load on the load-elongation curve by the fineness, and the elongation at that point is calculated as the breaking elongation (%). D.Dry heat shrinkage rate The 150°C dry heat shrinkage was measured according to the method of JIS L1013 (1999) 8.18.2b using a dryer heated to 150°C. E. Number of fluff The drawn yarn was placed on a creel, tension was applied to the yarn with a ring tensor, and the yarn was passed through a laser-type detector (Flufe Detector, manufactured by Daikosha) and measured at a measurement speed of 400 m / min. 100,000 m per yarn was measured and converted to the number per million m. Next, the average number of 10 yarns was calculated to obtain the number of fuzz per million m. F. Evaluation of yarn breakage during spinning and drawing (overall evaluation) If the bobbin could not be collected or wound at the time of spinning, or if the yarn broke just below the nozzle when sucked with a sucker, it was marked as "X". If one or more of the following occurred, such as a single yarn wrapping or yarn breakage on the stretching roller during drawing, or the number of fuzz pieces per 1 million meters in the fuzz test exceeded the following numbers, it was marked as "△". If the product could be collected without any problems, it was marked as "O" instead of "X" or "△",

[0038] Example 1 p-Polyphenylene sulfide resin (moisture content: 20 ppm) with MFR of 160 g / 10 min was prepared and melted at a spinning temperature of 328°C. The melted polyphenylene sulfide was extruded using a spinning nozzle (L / D: 0.35 mm / 0.17 mm) with 72 holes at a discharge rate such that the fineness of the undrawn yarn was 120 dtex. The extruded polyphenylene sulfide yarn was cooled with cold air at 25°C in a uniflow type cooling device. The yarn was then oiled using an oiling nozzle with 18% by mass of a water-based emulsion oil consisting of 95% by mass of smoothening agents and emulsifiers such as fatty acid esters and mineral oils, and 5% by mass of a copolymer polyether component per main oil component (amount of oil applied to yarn: 0.8% by mass).The yarn was then passed through two unheated godet rolls at a speed of 1,570 m / min, and the bobbin was wound using a winder to obtain a 6 kg winding bobbin of undrawn polyphenylene sulfide yarn for cut fiber.

[0039] Example 2 p-Polyphenylene sulfide resin (moisture content: 20 ppm) with MFR of 160 g / 10 min was prepared and melted at a spinning temperature of 328 ° C. The molten polyphenylene sulfide was discharged using a spinning nozzle (L / D: 0.35 mm / 0.17 mm) with 72 holes at a discharge rate that resulted in an undrawn fineness of 269 dtex. The discharged polyphenylene sulfide yarn was cooled with cold air at 25 ° C. in a uniflow type cooling device. Thereafter, the yarn was given an oiling agent composed of 95 mass % of a smoothing agent such as fatty acid ester and mineral oil, emulsifier, and 5 mass % of a copolymerized polyether component per oiling agent main component, and 18 mass % of the oiling agent was applied to the yarn with an oiling nozzle (amount of oiling agent attached to the yarn: 0.8 mass %). Next, the yarn was passed through two unheated godet rolls at a speed of 1570 m / min, and the bobbin was wound up with a winder to obtain a polyphenylene sulfide undrawn yarn bobbin. In the next drawing process, the yarn was drawn using a drawing machine consisting of a creel, an unheated feed roll (1stR), a preheating heater roll (2ndR), a plate heater for heat setting installed between the draw rolls, and a winding section. The undrawn yarn bobbin was placed on the creel, preheated at 100°C, drawn 3.2 times, heat set at 172°C, and wound up at a drawing speed of 800 m / min to obtain a polyphenylene sulfide drawn yarn.

[0040] Comparative Example 1 In the spinning process, the yarn was discharged at a discharge rate such that the undrawn fineness was 294 dtex, and the yarn was obtained into an undrawn bobbin at a speed of 900 m / min. In the drawing process, the draw ratio was set to 3.5 times, and other than these, a polyphenylene sulfide drawn yarn was obtained in the same manner as in Example 2.

[0041] Comparative Example 2 A polyphenylene sulfide fiber was obtained in the same manner as in Example 1, except that a spinning nozzle (L / D: 0.35 mm / 0.17 mm) was used to extrude the yarn at a throughput rate such that the yarn had a fineness of 84 dtex, the yarn was passed through two unheated godet rolls at a speed of 3150 m / min, and the yarn was wound around a bobbin with a winder to obtain a polyphenylene sulfide semi-drawn yarn.

[0042] Example 3 p-Polyphenylene sulfide resin (moisture content: 20 ppm) with MFR of 160 g / 10 min was prepared and melted at a spinning temperature of 328 ° C. The molten polyphenylene sulfide was discharged using a spinning nozzle (L / D: 0.6 mm / 0.6 mm) with two holes at a discharge rate such that the fineness of the undrawn yarn was 116 dtex. The discharged polyphenylene sulfide yarn was cooled with cold air at 25 ° C. in a uniflow type cooling device. After that, the yarn was given an aqueous emulsion oil solution adjusted to 10 mass % with an oil solution composed of 88 mass % of a smoothing agent and emulsifier such as fatty acid ester and mineral oil and 12 mass % of a copolymerized polyether component by an oiling nozzle (amount of oil attached to the yarn: 0.35 mass %). Next, the yarn was passed through two unheated godet rolls at a speed of 1560 m / min, and the bobbin was wound with a winder to obtain a polyphenylene sulfide undrawn yarn bobbin. In the next drawing process, a drawing machine consisting of a creel, an unheated feed roll (1stR), a roll heater for preheating (2ndR), a cold roll (3rdR), a plate heater for heat setting installed between the cold roll and the draw roll, and a winding section was used. The undrawn yarn bobbin was placed on the creel, preheated at 100°C, drawn 3.5 times, heat set at 180°C, relaxed at 0.96 times, and wound at a drawing speed of 800 m / min to obtain a polyphenylene sulfide drawn yarn.

[0043] Comparative Example 3 A polyphenylene sulfide drawn yarn was obtained in the same manner as in Example 3, except that a spinning nozzle (L / D: 0.45 mm / 0.6 mm) was used.

[0044] Example 4 p-Polyphenylene sulfide resin (moisture content: 20 ppm) with MFR of 160 g / 10 min was prepared and melted at a spinning temperature of 328°C. The melted polyphenylene sulfide was discharged using a spinning nozzle (L / D: 0.5 mm / 0.23 mm) with 72 holes at a discharge rate such that the fineness of the undrawn yarn was 850 dtex. The discharged polyphenylene sulfide yarn was cooled with cold air at 25°C in a uniflow type cooling device. The yarn was then oiled with 50% by mass of a lubricant and emulsifier such as fatty acid ester and mineral oil, and 50% by mass of potassium octylphosphonate, which was adjusted to an 18% by mass aqueous emulsion oil and applied with an oiling nozzle (amount of oil attached to yarn: 1% by mass), and then the yarn was passed through two unheated godet rolls at a speed of 1550 m / min and wound into a bobbin with a winder to obtain a bobbin of undrawn polyphenylene sulfide yarn. In the next drawing process, a drawing machine was used, which was composed of a creel, an unheated feed roll (1stR), a heater roll (2ndR) for preheating, two heater rolls (3rdR, 4thR) for heat setting, a draw roll (5thR), and a winding section. An undrawn bobbin was placed on a creel, preheated at the 2ndR (100°C), and heat-set at the 3rdR (110°C) and 4thR (220°C). The bobbin was drawn at draw ratios of 1.03x, 3.38x, 1.00x, and 0.978x between the 1st and 2ndR, 2nd and 3rdR, 3rd and 4thR, and 4th and 5thR, respectively, and then wound up at a drawing speed of 800m / min to obtain a low-heat drawn polyphenylene sulfide yarn.

[0045] [Comparative Examples 4 to 6] A low dry heat property polyphenylene sulfide drawn yarn was obtained in the same manner as in Example 4, except that the spinning nozzles were changed to those (L / D: 1 mm / 0.23 mm, 0.18 mm / 0.23 mm, 0.35 mm / 0.15 mm).

[0046] Example 5 The spinning speed was changed to 900 m / min, a bobbin of undrawn yarn having a fineness of 1060 dtex was obtained, the undrawn bobbin was placed on a creel, preheated at the 2ndR (100°C), and set to 0 heat at the 3rdR (110°C) and 4thR (220°C). Except for the fact that the draw ratios of the 1st-2ndR DR, the 2nd-3rdR DR, the 3rd-4thR DR, and the 4th-5thR DR were 1.03 times, 4.27 times, 1.00 times, and 0.978 times, respectively, a polyphenylene sulfide drawn yarn with low dry heat properties was obtained in the same manner as in Example 4.

[0047] Example 6 A polyphenylene sulfide drawn yarn having low dry heat properties was obtained in the same manner as in Example 5, except that a spinning nozzle (L / D: 35 mm / 0.17 mm) was used.

[0048] Example 7 p-Polyphenylene sulfide resin (moisture content: 20 ppm) with MFR of 160 g / 10 min was prepared and melted at a spinning temperature of 328 ° C. The molten polyphenylene sulfide was discharged using a spinning nozzle (L / D: 0.5 mm / 0.23 mm) with 72 holes at a discharge rate such that the fineness of the undrawn yarn was 250 dtex. The discharged polyphenylene sulfide yarn was cooled with cold air at 25 ° C. in a uniflow type cooling device. Thereafter, the yarn was treated with an oil solution composed of 50 mass % of a smoothing agent such as fatty acid ester and mineral oil and an emulsifier, and 50 mass % of potassium octylphosphonate, which was adjusted to 18 mass % of an aqueous emulsion oil solution, and applied with an oiling nozzle (amount of oil attached to the yarn: 1 mass %). The yarn was then passed through two unheated godet rolls at a speed of 3200 m / min and wound onto a bobbin using a winder to obtain a bobbin of semi-drawn polyphenylene sulfide yarn.

[0049] Example 8 p-Polyphenylene sulfide resin (moisture content: 20 ppm) with MFR of 160 g / 10 min was prepared and melted at a spinning temperature of 328 ° C. The molten polyphenylene sulfide was discharged using a spinning nozzle (L / D: 0.4 mm / 0.2 mm) with 72 holes at a discharge rate such that the fineness of the undrawn yarn was 548 dtex. The discharged polyphenylene sulfide yarn was cooled with cold air at 25 ° C. in a uniflow type cooling device. The yarn was then treated with an oil solution composed of 50 mass % of an oil solution of a smoothing agent such as a fatty acid ester and a mineral oil, an emulsifier component, and 50 mass % of potassium octylphosphonate, which was adjusted to 18 mass % of an aqueous emulsion oil solution, and applied with an oiling nozzle (amount of oil attached to the yarn: 1 mass %). Next, the yarn was passed through two unheated godet rolls at a speed of 1200 m / min and wound up on a bobbin with a winder to obtain a bobbin of undrawn polyphenylene sulfide yarn. In the next drawing process, a drawing machine was used, which was composed of a creel, an unheated 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. An undrawn bobbin was placed on a creel, preheated at the 2ndR (100°C), and heat-set at the 3rdR (110°C) and 4thR (220°C). The bobbin was then drawn at draw ratios of 1.03x, 3.26x, 1.00x, and 0.978x for the 1st-2ndR DR, 2nd-3rdR DR, 3rd-4thR DR, and 4th-5thR DR, respectively, and taken up at a drawing speed of 800m / min to obtain a polyphenylene sulfide drawn yarn with low dry heat properties.

[0050] Example 9 A low dry heat polyphenylene sulfide drawn yarn was obtained in the same manner as in Example 8, except that the spinning nozzle (L / D: 0.5 mm / 0.23 mm) and the spinning oil solution used was 100 mass% potassium octylphosphonate, which was changed to 18 mass% water-based emulsion oil solution.

[0051] Example 10 A low dry heat polyphenylene sulfide drawn yarn was obtained in the same manner as in Example 8, except that the spinning nozzle (L / D: 0.5 mm / 0.25 mm) was used.

[0052] Example 11 A spinning nozzle (L / D: 0.4 mm / 0.2 mm) was used to obtain a bobbin of undrawn yarn having an undrawn fineness of 565 dtex at a spinning speed of 1000 m / min. In the drawing process, the bobbin of undrawn yarn was placed on a creel, preheated at the 2ndR (100°C), heat-set at the 3rdR (110°C) and 4thR (220°C), and drawn at draw ratios of 1.03 times / 3.36 times / 1.00 times / 0.978 times for the 1st-2ndR DR / 2nd-3rdR DR / 3rd-4thR DR / 4th-5thR DR, respectively, and taken up at a drawing speed of 800 m / min. Except for this, a polyphenylene sulfide drawn yarn with low dry heat properties was obtained in the same manner as in Example 8.

[0053] [Comparative Examples 7 to 10] Using spinning nozzles (L / D = 0.4 mm / 0.2 mm, 0.5 mm / 0.23 mm, 0.5 mm / 0.25 mm, 0.4 mm / 0.16 mm), a bobbin of undrawn yarn with a fineness of 581 dtex was obtained at a spinning speed of 800 m / min. In the drawing process, the bobbin of undrawn yarn was placed on a creel, preheated at 2ndR (100 °C), 3rdR (110 °C), and A low-heat drawn polyphenylene sulfide yarn was obtained in the same manner as in Example 10, except that the yarn was heat-set to 4thR (220°C), and the draw ratios of the 1st-2ndR DR, the 2nd-3rdR DR, the 3rd-4thR DR, and the 4th-5thR DR were 1.03 times / 3.46 times / 1.00 times / 0.978 times, and the yarn was taken up at a drawing speed of 800 m / min.

[0054] Tables 1 and 2 show the production conditions, yarn properties, and evaluation results of the polyphenylene sulfides of Examples 1 to 11 and Comparative Examples 1 to 10. [Table 1] [Table 2]

[0055] According to the method for producing polyphenylene sulfide fiber of Examples 1 to 11, in which the L / D of the spinning nozzle hole, the spinning draft and the shear rate were controlled and a specific spinning oil was used in combination, the spinning and drawing operability was greatly improved, and the obtained fiber had a significantly reduced amount of fuzz and was of good quality. In addition, the subsequent post-processing process was also very good, and a high-quality product was obtained. The spinning draft at the nozzle hole is 120, and the shear rate is 3992 sec -1 According to the manufacturing method of Comparative Example 1, which had such a low back pressure at the nozzle hole, the moment the yarn was wound around the godet roll during spinning, yarn breakage frequently occurred just below the nozzle, and bobbins of polyphenylene sulfide fiber could not be obtained. The polyphenylene sulfide semi-drawn fiber obtained from Comparative Example 2, which had a very high spinning draft, was significantly thinned just below the nozzle and single fiber breakage occurred. The number of fuzz particles detected per 1 million meters was 12 on average, indicating poor fiber quality and poor spinning operability. According to the manufacturing method of Comparative Example 3, in which the L / D is small at 0.75, the back pressure of the nozzle hole was unstable, the polymer swell directly below the nozzle was not perpendicular to the nozzle surface, and was discharged at a strange inclination, resulting in many problems during spinning, and many thread breaks occurred directly below the nozzle of the spinneret, and the spinning operability was also poor. In addition, the obtained fibers had uneven thickness, resulting in poor yarn quality. According to the manufacturing method of Comparative Example 4 in which the L / D was high at 4.35, the back pressure at the nozzle hole of the spinneret became high, and the increased back pressure in the pack made it difficult to perform long-term spinning, and normal spinning was not possible. According to the manufacturing method of Comparative Example 5, in which the L / D ratio is small at 0.78, the back pressure at the nozzle hole of the spinneret was unstable, and the polymer swell directly below the nozzle was discharged in a strange direction, causing many problems during spinning, and many thread breaks occurred directly below the nozzle of the spinneret, and the spinning operability was poor. In addition, the obtained fibers had uneven thickness, resulting in poor yarn quality. According to the manufacturing method of Comparative Example 6, in which the shear rate was high, a large amount of polymer was flowed into the small diameter nozzle hole of the spinneret, so the shear rate became high and the back pressure at the nozzle hole was sufficient, but the back pressure inside the pack became very high and approached the upper limit of the back pressure, making it impossible to collect a full winding onto the bobbin. In the manufacturing methods of Comparative Examples 7 to 9 in which the shear rate at the nozzle hole was low, the back pressure at the nozzle hole of the spinneret was insufficient, and the moment the yarn was wound around the godet roll during spinning, yarn breakage frequently occurred just below the nozzle, and polyphenylene sulfide fiber could not be collected on a bobbin. Moreover, according to the production method of Comparative Example 10, in which the spinning draft was low, spinning was not possible.

[0056] Thus, the polyphenylene sulfide fiber manufacturing methods obtained in Examples 1 to 11 had excellent spinning and drawing operability. The obtained polyphenylene sulfide fibers had a significantly reduced amount of fuzz in the fibers and were of good quality. In addition, the fibers had excellent passability in subsequent processes such as warping, weaving, and processing, and good quality fabrics were obtained. The obtained fibers and fabrics can be suitably applied to various products.

Claims

1. A method for producing a polyphenylene sulfide fiber, the main constituent unit of which is a p-phenylene sulfide unit, is performed by using a spinneret in which the relationship between the spinning draft of a spinneret nozzle hole portion and the shear rate satisfies any one of conditions (1) to (5), and L / D, which is the ratio of the land length (L) of the spinneret nozzle hole portion to the diameter (D) of the nozzle hole, is 0.8 to 4. (1) When the spinning draft is 5 or more and less than 7.5, the shear rate is 85,000 to 140,000 (2) When the spinning draft is 7.5 or more and less than 9.5, the shear rate is 60,000 to 100,000 (3) When the spinning draft is 9.5 or more and less than 14, the shear rate is 45,000 to 80,000 (4) When the spinning draft is 14 or more but less than 18, the shear rate is 20,000 to 60,000 (5) When the spinning draft is 18 or more but less than 180, the shear rate is 5,000 to 40,000

2. 2. The method for producing polyphenylene sulfide fiber according to claim 1, characterized in that the spinning oil contains, as a component, a single-component polyether selected from the group consisting of polyethylene glycol, polypropylene glycol, and polybutylene glycol, or a copolymer polyether obtained by copolymerizing two or more of them.

3. 2. The method for producing a low dry heat polyphenylene sulfide fiber according to claim 1, wherein the spinning oil contains an octylphosphonate salt.

4. A polyphenylene sulfide fiber having a single yarn fineness of 4 dtex or more and a fluff count of 2 or less per 1,000,000 meters.

5. A polyphenylene sulfide fiber having a single yarn fineness of more than 2 dtex and less than 4 dtex and having 5 or less pieces of fuzz per 1,000,000 meters.

6. A polyphenylene sulfide fiber having a single yarn fineness of 2 dtex or less and a fluff count of 8 or less per 1,000,000 meters.

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