DILUTED SOLUTION OF SYNTHETIC FIBER TREATMENT AGENT, AND METHOD FOR MANUFACTURING SYNTHETIC FIBERS

Abstract

 This diluted solution of a synthetic fiber treatment agent contains: a synthetic fiber treatment agent containing a smoothing agent, a non-ionic surfactant, and an antistatic agent; and a volatile diluent. When the total of the proportions of the synthetic fiber treatment agent and the volatile diluent in the diluted solution is defined as 100% by mass, the proportion of the synthetic fiber treatment agent is equal to or greater than 60% by mass and less than 100% by mass, and the proportion of the volatile diluent is greater than 0% by mass and less than or equal to 40% by mass, the kinematic viscosity of the diluted solution at 30°C being greater than 0 mm²/s and less than 80 mm²/s, and the diluted solution being applicable to a prescribed spinning/stretching step in which there is used a spinning/stretching machine comprising a plurality of heating rollers for stretching a spun yarn.

Description

TECHNICAL FIELD

[0001] The present invention relates to a diluted solution of a synthetic fiber treatment agent that can sufficiently prevent oil drop in a spinning and stretching method in which the number of winding turns of a yarn on a heating roller is small, ensures good spinnability, and can improve the yarn quality and dyeability of the obtained yarn, and also relates to a method for manufacturing a synthetic fiber.

BACKGROUND ART

[0002] From the viewpoint of improving productivity, synthetic fibers such as polyester fibers are generally produced by a direct spinning and stretching method in which a melt-spun filament is immediately stretched and then wound. The direct spinning and stretching method is performed using a spinning and stretching machine in which an aqueous oil agent (diluted solution of a synthetic fiber treatment agent) for imparting functions such as smoothness is adhered to the surface of a melt-spun yarn and stretching is carried out with a plurality of rollers such as heating rollers.

[0003] In Patent Document1, a spun yarn is stretched by two heating rollers. Each heating roller is provided with a separation roller, and the yarn is wound around the heating roller and the separation roller a plurality of times. The yarn is heated by the upstream heating roller to a temperature equal to or higher than the glass transition temperature and then stretched between the two heating rollers.

[0004] In Patent Document 2, a yarn is wound and stretched in a partial-winding state in which the winding angles around a plurality of heating rollers are each less than 360 degrees. At this time, a diluted solution of a synthetic fiber treatment agent which has a treatment agent concentration in the diluted solution of 40% to 60% by mass and a kinematic viscosity at 30°C of 100 to 200 mm²/s is applied to the yarn to be stretched.

PRIOR ART LITERATURE

PATENT LITERATURE

[0005] 

Patent Document 1: Japanese Laid-Open Patent Publication No. 6-17312

Patent Document 2: Japanese Laid-Open Patent Publication No. 2014-70294

SUMMARY OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

[0006] Patent Document 1 uses a diluted solution of a synthetic fiber treatment agent having a high water content, that is, a diluted solution of a synthetic fiber treatment agent having a low concentration of the synthetic fiber treatment agent, in a synthetic fiber spinning step. For this reason, when the yarn is heated to a predetermined temperature by the heating roller, a large amount of heat is consumed to evaporate the moisture in the diluted solution, and thus the thermal efficiency is poor. As a result, unevenness of thermal history during yarn stretching are likely to be induced, and there is a problem in dyeability of the yarn. When the contact length of the yarn with the heating roller is increased, the heat is sufficiently transferred to the yarn, and the problem of dyeability caused by unevenness of thermal history is resolved. However, the resulting problem is that the yarn has to be wound many times around a single heating roller, and thus the heating roller has to be increased in length in the axial direction, so that the workability of yarn winding becomes worse.

[0007] With the diluted solution of a synthetic fiber treatment agent used in Patent Document 2, thermal efficiency when heating the yarn is not high, and the resulting problem, which is the same as in Patent Document 1, is that sufficient dyeability of the yarn cannot be obtained. Therefore, it is necessary to increase the number of heating rollers or increase the outer shape of the heating roller in order to increase the contact length of the yarn to the heating roller. Meanwhile, a problem arising when the synthetic fiber treatment agent in the diluted solution is used at a higher concentration is that the kinematic viscosity is further increased, so that an oil drop occurs and the yarn quality deteriorates.

[0008] The problem to be solved by the present invention is to provide a diluted solution of a synthetic fiber treatment agent that can sufficiently prevent oil drop, ensures good spinnability, and can improve the yarn quality and dyeability of the obtained yarn in a spinning and stretching method in which the number of winding turns of the yarn on a heating roller is small, and also to provide a method for manufacturing a synthetic fiber that uses the diluted solution.

MEANS FOR SOLVING THE PROBLEM

[0009] As a result of researches conducted to solve the above-mentioned problem, the inventors of the present invention have found that a diluted solution including a synthetic fiber treatment agent in a specific proportion range and having a viscosity within a specific range is surely suitable as a diluted solution of a synthetic fiber treatment agent used in a spinning and stretching step using a spinning and stretching machine equipped with a plurality of heating rollers, this step being a spinning and stretching method in which the yarn is wound around each heating roller more than 0 times and 3 or fewer times.

[0010] That is, one aspect of the present invention is a diluted solution of a synthetic fiber treatment agent that contains a synthetic fiber treatment agent including a smoothing agent, a nonionic surfactant, and an antistatic agent, and a volatile diluent. Where the total content of the synthetic fiber treatment agent and the volatile diluent in the diluted solution is taken as 100% by mass, the proportion of the synthetic fiber treatment agent is 60% by mass or more and less than 100% by mass, and the proportion of the volatile diluent is greater than 0% by mass and equal to or less than 40% by mass. The diluted solution has a kinematic viscosity at 30°C of greater than 0 mm²/s and less than 80 mm²/s. The diluted solution is used in a spinning and stretching step using a spinning and stretching machine equipped with a plurality of heating rollers for stretching a spun yarn, this step being a spinning and stretching method in which the yarn is wound around each heating roller more than 0 times and 3 or fewer times.

[0011] The kinematic viscosity at 30°C of a non-volatile fraction in the diluted solution is preferably 10 to 70 mm²/s.

[0012] The kinematic viscosity at 30°C of the diluted solution is preferably 10 to 70 mm²/s.

[0013] The kinematic viscosity at 30°C of the diluted solution is preferably 20 to 65 mm²/s.

[0014] Where the total content of the synthetic fiber treatment agent and the volatile diluent in the diluted solution is taken as 100% by mass, the proportion of the synthetic fiber treatment agent is preferably 65% to 98% by mass, and the proportion of the volatile diluent is preferably 2% to 35% by mass.

[0015] The proportion of the synthetic fiber treatment agent is preferably 70% to 95% by mass, and the proportion of the volatile diluent is preferably 5% to 30% by mass.

[0016] The proportion of the synthetic fiber treatment agent is preferably 75% to 92% by mass, and the proportion of the volatile diluent is preferably 8% to 25% by mass.

[0017] The volatile diluent preferably contains water.

[0018] The smoothing agent preferably contains a fatty acid ester having a total of 24 to 32 carbon atoms in a molecule.

[0019] The antistatic agent preferably contains at least one compound selected from a fatty acid salt, an organic phosphate, an organic sulfonate, an amphoteric compound, and a quaternary ammonium salt.

[0020] Where the total content of the smoothing agent, nonionic surfactant, and antistatic agent in the synthetic fiber treatment agent is taken as 100% by mass, it is preferable that the proportion of the smoothing agent is 30% to 80% by mass, the proportion of the nonionic surfactant is 5% to 70% by mass, and the proportion of the antistatic agent is 1% to 20% by mass.

[0021] A method for manufacturing a synthetic fiber according to another aspect of the present invention comprises a step of adhering the diluted solution of a synthetic fiber treatment agent to a synthetic fiber yarn so that the proportion of the synthetic fiber treatment agent to the yarn is 0.1 % to 20% by mass, and a spinning and stretching step using a spinning and stretching machine equipped with a plurality of heating rollers for stretching a spun yarn, wherein the yarn is wound around each heating roller more than 0 times and 3 or fewer times.

EFFECT OF THE INVENTION

[0022] The present invention succeeds in sufficiently preventing oil drop, ensuring good spinnability, and improving the yarn quality and dyeability of the obtained yarn.

MODE FOR CARRYING OUT THE INVENTION

(First Embodiment)

[0023] Initially, a first embodiment that embodies the diluted solution of a synthetic fiber treatment agent according to the present invention (hereinafter also simply referred to as diluted solution) will be described. The diluted solution of the present embodiment contains a synthetic fiber treatment agent including a smoothing agent, a nonionic surfactant, and an antistatic agent, and a volatile diluent. Where the total content of the synthetic fiber treatment agent and the volatile diluent in the diluted solution is taken as 100% by mass, the proportion of the synthetic fiber treatment agent is 60% by mass or more and less than 100% by mass, and the proportion of the volatile diluent is greater than 0% by mass and equal to or less than 40% by mass. Further, the diluted solution of the present embodiment has a kinematic viscosity at 30°C of greater than 0 mm²/s and less than 80 mm²/s and is used in a spinning and stretching step using a spinning and stretching machine equipped with a plurality of heating rollers for stretching a spun yarn, this step being a spinning and stretching method in which the yarn is wound around each heating roller more than 0 times and 3 or fewer times.

[0024] The synthetic fiber treatment agent to be used for the diluted solution of the present embodiment contains, as described above, a smoothing agent, a nonionic surfactant, and an antistatic agent.

[0025] The smoothing agent to be used for the synthetic fiber treatment agent for the diluted solution of the present embodiment is not particularly limited and examples thereof include: (1) ester compounds of aliphatic monohydric alcohols and aliphatic monocarboxylic acids, such as butyl stearate, octyl stearate, oleyl laurate, oleyl oleate, isopentacosanyl isostearate, octyl palmitate, octyl laurate, isotridecyl stearate, lauryl laurate, lauryl oleate, and lauryl stearate; (2) ester compounds of aliphatic polyhydric alcohols and aliphatic monocarboxylic acids, such as 1,6-hexanediol didecanate, glycerol trioleate, trimethylolpropane trioleate, and trimethylolpropane trilaurate; (3) ester compounds of aliphatic monohydric alcohols and aliphatic polycarboxylic acids, such as dioctyl adipate, dilauryl adipate, dioleyl azelate, and diisocetylthiodipropionate; (4) ester compounds of aromatic monohydric alcohols and aliphatic monocarboxylic acids, such as benzyl oleate and benzyl laurate; (5) ester compounds of aromatic polyhydric alcohols and aliphatic monocarboxylic acids, such as bisphenol A dilaurate and bisphenol A dioleate; (6) ester compounds of aliphatic monohydric alcohols and aromatic polycarboxylic acids, such as bis-2-ethylhexyl phthalate, diisostearyl isophthalate, and trioctyl trimellitate; (7) natural fats and oils, such as coconut oil, rapeseed oil, sunflower oil, soybean oil, castor oil, sesame oil, fish oil, and beef tallow; and (8) known smoothing agents that have been used for synthetic fiber treatment agents, such as mineral oils. These smoothing agents can be used singly or in a mixture of two or more. Among these, from the viewpoint of more excellent effect of the present invention, the smoothing agent preferably contains a fatty acid ester having a total of 24 to 32 carbon atoms in the molecule, such as octyl stearate, oleyl laurate, octyl palmitate, isotridecyl stearate, lauryl laurate, lauryl oleate, lauryl stearate, 1,6-hexanediol didecanate, dilauryl adipate, or benzyl oleate.

[0026] The nonionic surfactant to be used for the synthetic fiber treatment agent for the diluted solution of the present embodiment is not particularly limited and examples thereof include: (1) compounds obtained by adding an alkylene oxide having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, 1,2-butylene oxide, and 1,4-butylene oxide, to at least one kind of molecule selected from organic acids, organic alcohols, organic amines, and organic amides, such as polyoxyethylene laurate, polyoxyethylene oleate, polyoxyethylene methyl ether laurate, polyoxyethylene octyl ether laurate, bis polyoxyethylene lauryl ether adipate, polyoxyethylene dilaurate, polyoxyethylene dioleate, polyoxyethylene octyl ether, polyoxyethylene lauryl ether, polyoxyethylene isotridecyl ether, polyoxyethylene oleyl ether, polyoxypropylene lauryl ether, polyoxybutylene oleyl ether, polyoxyethylene polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene lauryl ether, polyoxyethylene polyoxypropylene nonylphenyl ether, polyoxyethylene lauryl amino ether, polyoxyethylene lauroamide ether, diethylene glycol, triethylene glycol, and ethylene glycol monobutyl ether; (2) polyhydric alcohol partial ester type nonionic surfactants, such as sorbitan monooleate and sorbitan trioleate; (3) polyoxyalkylene polyhydric alcohol fatty acid ester type nonionic surfactants, such as polyoxyethylene sorbitan trioleate, polyoxyethylene castor oil ether, polyoxyethylene polyoxypropylene hydrogenated castor oil ether, polyoxyethylene hydrogenated castor oil ether diolate, and polyoxyethylene hydrogenated castor oil ether trilaurate; (4) fatty acid amide type nonionic surfactants, such as lauric acid diethanolamide and oleic acid diethanolamide; (5) polyoxyalkylene fatty acid amide type nonionic surfactants, such as polyoxyethylene oleic acid diethanolamide; (6) higher fatty acids, such as lauric acid, oleic acid, and stearic acid; and (7) higher alcohols, such as lauryl alcohol, oleyl alcohol, and stearyl alcohol. These nonionic surfactants can be used singly or in a mixture of two or more.

[0027] The antistatic agent to be used for the synthetic fiber treatment agent for the diluted solution of the present embodiment is not particularly limited and examples thereof include: (1) fatty acid salts, such as potassium acetate, potassium octylate, and potassium oleate; (2) organic sulfonic acid salts, such as decane sulfonate potassium salt, alkyl (carbon number 12 to 15) sulfonate sodium salts, and tetradecane sulfonate sodium salt; (3) organic sulfuric acid salts, such as sodium dodecyl sulfate; (4) organic phosphoric acid salts, such as lauryl phosphoric acid ester potassium salt, oleyl phosphoric acid ester potassium salt, a salt of polyoxyethylene oleyl phosphoric acid ester and polyoxyethylene lauryl amino ether, and polyoxyethylene polyoxypropylene lauryl phosphoric acid ester potassium salt; (5) amphoteric compounds, such as octyldimethylammonia acetate, N,N-bis(2-carboxyethyl)-octylamine sodium, N-oleyl-N'-carboxylethyl-N'-hydroxyethyl-ethylenediamine sodium; and (6) quaternary ammonium salts, such as dimethyloctylammonium trimethylphosphate and dimethyldodecylammonium trimethylphosphate. These antistatic agents can be used singly or in a mixture of two or more. Among these, from the viewpoint of more excellent effect of the present invention, the antistatic agent preferably contains at least one compound selected from a fatty acid salt, an organic phosphoric acid salt, an organic sulfonic acid salt, an amphoteric compound, and a quaternary ammonium salt.

[0028] Where the total content of the above-described smoothing agent, nonionic surfactant, and antistatic agent in the synthetic fiber treatment agent to be used in the diluted solution of the present embodiment is taken as 100% by mass, it is preferable that the proportion of the smoothing agent is 30% to 80% by mass, the proportion of the nonionic surfactant is 5% to 70% by mass, and the proportion of the antistatic agent is 1% to 20% by mass. By specifying the proportions within these ranges, the effect of the present invention can be further improved.

[0029] The volatile diluent to be used in the diluted solution of the present embodiment is not particularly limited and examples thereof include water, organic solvents, and low viscosity mineral oils. Specific examples of the organic solvents include hexane, ethanol, isopropanol, ethylene glycol, propylene glycol, diethyl ether, toluene, xylene, dimethylformamide, methyl ethyl ketone, and chloroform. Specific examples of the low-viscosity mineral oils include mineral oils having a kinematic viscosity at 30°C of 5 mm²/s or less, and more specifically, paraffin having 11 to 13 carbon atoms (for example, trade name: N-Paraffin No. 1408, manufactured by Sasol Limited), paraffin having 12 carbon atoms (for example, trade name: Cactus Normal Paraffin N-12D, manufactured by Japan Energy Corporation), paraffin having 13-15 carbon atoms (for example, trade name: Cactus Normal Paraffin YHNP, manufactured by Japan Energy Corporation), and paraffin having 14 carbon atoms (for example, trade name: Cactus Normal Paraffin N-14, manufactured by Japan Energy Corporation). These volatile diluents can be used singly or in a mixture of two or more within a compatibility range. Among these, from the viewpoint of more excellent effect of the present invention, the volatile diluent preferably contains water.

[0030] Where the total content of the above-described synthetic fiber treatment agent and volatile diluent in the diluted solution of the present embodiment is taken as 100% by mass, the proportion of the synthetic fiber treatment agent is 60% by mass or more and less than 100% by mass, and the proportion of the volatile diluent is greater than 0% by mass and equal to or less than 40% by mass. The proportion is preferably 65% to 98% by mass for the synthetic fiber treatment agent and 2% to 35% by mass for the volatile diluent, more preferably 70% to 95% by mass for the synthetic fiber treatment agent and 5% to 30% by mass for the volatile diluent, and even more preferably 75% to 92% by mass for the synthetic fiber treatment agent and 8% to 25% by mass for the volatile diluent. By specifying the proportions within these ranges, the effects of the present invention, in particular, the spinnability, yarn quality, and dyeability can be further improved.

[0031] The kinematic viscosity at 30°C of the diluted solution of the present embodiment is greater than 0 mm²/s and less than 80 mm²/s, preferably 10 to 70 mm²/s, and more preferably 20 to 65 mm²/s. By specifying the kinematic viscosity within these ranges, the effects of the present invention can be further improved. The kinematic viscosity was measured using a Cannon-Fenske viscometer (hereinafter the same).

[0032] The kinematic viscosity at 30°C of a non-volatile fraction in the diluted solution of the present embodiment is not particularly limited, but is preferably 10 to 70 mm²/s. By specifying the kinematic viscosity within these ranges, the effects of the present invention, in particular, the oil drop suppressing effect, yarn quality, and dyeability can be further improved.

[0033] The non-volatile fraction means an absolutely dried product obtained by sufficiently removing the volatile diluent by heat-treating the diluted solution of the present embodiment at 105°C for 2 hours.

[0034] The diluted solution of the present embodiment may purposively contain other components, for example, an antifoaming agent (such as silicone compound and mineral oil), an antioxidant, a preservative, and a rust inhibitor. The amount of other components used can be specified within a range in which the effects of the present invention are not impaired, but is preferably as small as possible.

[0035] The diluted solution of the present embodiment is used in a spinning and stretching step using a spinning and stretching machine equipped with a plurality of heating rollers for stretching a spun yarn, this step being a spinning and stretching method in which the yarn is wound around each heating roller more than 0 times and 3 or fewer times.

[0036] The yarn supplied to the spinning and stretching machine is stretched by a plurality of rollers including two or more heating rollers. At this time, the yarn to be stretched is wound around each roller more than 0 times and 3 or fewer times. When the separation roller is used in combination, winding more than 0 times and 3 or fewer times is inclusive of a state where the yarn is wound once, twice, or three times between the heating roller and the separation roller. Further, winding more than 0 times and less than 1 time is inclusive of a state of partial winding on the heating roller. In such a configuration, the workability of winding increases, but the heating length at the time of stretching becomes shorter than when winding more than 3 times.

[0037] In the present embodiment, the diluted solution of the synthetic fiber treatment agent is supplied in a high-concentration state to the yarn that has been wound around the heating roller more than 0 times and 3 or fewer times. Therefore, the amount of heat consumed for the evaporation of the volatile diluent is small, the yarn can be sufficiently heated even with a short heating length, and the yarn of excellent quality can be obtained. Moreover, because an appropriately low viscosity of the diluted solution of this embodiment can be maintained, oil drop during oiling can be prevented.

(Second Embodiment)

[0038] A second embodiment embodying a method for manufacturing a synthetic fiber according to the present invention (hereinafter referred to as manufacturing method) will be described hereinbelow. The manufacturing method of the present embodiment includes a step of adhering the diluted solution of the synthetic fiber treatment agent of the first embodiment to a synthetic fiber yarn so that the proportion of the synthetic fiber treatment agent to the yarn is 0.1% to 20% by mass. Also included is a spinning and stretching step using a spinning and stretching machine equipped with a plurality of heating rollers for stretching a spun yarn, wherein the yarn is wound around each heating roller more than 0 times and 3 or fewer times.

[0039] A synthetic fiber to be adhered with the diluted solution of the present embodiment is not particularly limited and examples thereof include (1) polyester fibers, such as polyethylene terephthalate, polypropylene terephthalate, and polylactic acid esters, (2) polyamide fibers, such as Nylon 6 and Nylon 66, (3) polyacryl fibers, such as polyacryl and modacryl, (4) polyolefin fibers, such as polyethylene and polypropylene, and polyurethane fibers. Among these, it is preferable to use polyester fibers or polyamide fibers. In such a case, the effect of the present invention can be further enhanced.

[0040] A known method can be used for adhering the treatment agent of the present embodiment, and examples thereof include a roller oiling method, a guide oiling method using a metering pump, an immersion oiling method, and a spray oiling method. Among these, it is preferable to use the guide oiling method. When such an oiling method is used, the effect of the present invention can be further enhanced.

[0041] With the diluted solution and the manufacturing method of the above embodiments, the following effects can be obtained.

(1) In the above-described embodiment, a diluted solution of a synthetic fiber treatment agent is provided that contains a synthetic fiber treatment agent including a smoothing agent, a nonionic surfactant, and an antistatic agent, and a volatile diluent, wherein the proportion of the synthetic fiber treatment agent in the diluted solution is 60% by mass or more and less than 100% by mass, and the proportion of the volatile diluent in the diluted solution is greater than 0% by mass and equal to or less than 40% by mass. Further, the kinematic viscosity at 30°C of the diluted solution is greater than 0 mm²/s and less than 80 mm²/s. Therefore, the viscosity of the diluted solution including the synthetic fiber treatment agent at a high concentration is maintained appropriately, oil drop in the spinning step can be sufficiently prevented, the spinnability is good, and the yarn quality and dyeability of the resulting yarn can be improved.

(2) The diluted solution of the above embodiment is applied to a yarn hung on a spinning and stretching machine in which stretching is performed by a plurality of rollers including two or more heating rollers. Since the yarn to be stretched is wound more than 0 times and 3 or fewer times around each roller, the workability of winding can be improved.

(3) The diluted solution of the above embodiment is used in a spinning and stretching method in which a yarn to be stretched is wound more than 0 times and 3 or fewer times around each roller. In this spinning and stretching method, the heating length at the time of stretching becomes shorter than that of the yarn wound more than three times. Since the diluted solution of the present embodiment is supplied with a synthetic fiber treatment agent at a high concentration, the amount of heat consumed for evaporation of the volatile diluent is small, the yarn is sufficiently heated even with a short heating length, and the yarn of excellent quality can be obtained.

[0042] The above embodiments may be modified as follows.

• In the present embodiment, the number of heating rollers of the spinning and stretching machine is not particularly limited as long as it is 2 or more, and can be appropriately set according to, for example, the kind of yarn and its use and purpose. For other features, the features of a known stretching machine can be adopted as appropriate.

EXAMPLES

[0043] Hereinafter, in order to make the configuration and effects of the present invention more specific, examples and the like will be described. However, the present invention is not limited to these examples. In the following examples and comparative examples, % means % by mass.

Test Category 1 (Preparation of diluted solution of synthetic fiber treatment agent)

- Example 1

[0044] A diluted solution of a synthetic fiber treatment agent of Example 1 was prepared by mixing a synthetic fiber treatment agent (P-1) at a proportion of 90% and water (D-1) as a volatile diluent at a proportion of 10%. The synthetic fiber treatment agent included a smoothing agent (40% of lauryl oleate (L-1), 12% of octyl palmitate (L-2), and 15% of mineral oil (L-4) with a kinematic viscosity at 30°C of 47 mm²/s), a nonionic surfactant (4% of polyoxyethylene (added mole number of ethylene oxide (hereinafter the same) is 4 mol) oleyl ether (N-4), 3% of polyoxyethylene (4 mol) isotridecyl ether (N-5), 3% of polyoxyethylene (5 mol) lauryl ether (N-6), 6% of polyoxyethylene (3 mol) monooleate (N-7), 5% of polyoxyethylene (25 mol) hydrogenated castor oil ether trilaurate (N-12), and 2% of oleic acid (N-17)), and an antistatic agent (4% of alkyl (carbon number 12 to 15) sulfonate sodium salt (An-1) and 6% of a salt of polyoxyethylene (4 mol) oleyl phosphate and polyoxyethylene (4 mol) lauryl amino ether (An-2)) for a total of 100%.

- Examples 2 to 8 and Comparative Examples 1 to 6

[0045] A diluted solution of a synthetic fiber treatment agent of each of Examples 2 to 8 and Comparative Examples 1 to 6 was prepared in the same manner as the diluted solution of a synthetic fiber treatment agent of Example 1. The kinds of the smoothing agent, nonionic surfactant, and antistatic agent in each synthetic fiber treatment agent and the proportion of each component in the case where the total content of the components is taken as 100% are shown in Table 1 for the diluted solution of a synthetic fiber treatment agent of each examples and comparative examples prepared above.

[0046] The kind of the volatile diluent and the proportions of the volatile diluent and the synthetic fiber treatment agent in each diluted solution in the case where the total content thereof is taken as 100% are shown in Table 2.









manufactured by Sasol Limited).

Test Category 2 (Measurement of kinematic viscosity of diluted solution of synthetic fiber treatment agent and non-volatile fraction thereof)

- Example 1

[0047] The kinematic viscosity at 30°C of the diluted solution of the synthetic fiber treatment agent (P-1) prepared in Test Category 1 was 62 mm²/s as measured by the Cannon-Fenske method. In addition, the kinematic viscosity at 30°C of the non-volatile fraction obtained by heat-treating the diluted solution of the synthetic fiber treatment agent (P-1) at 105°C for 2 hours and removing the volatile diluent was 48 mm²/s as measured by the Cannon-Fenske method.

- Examples 2 to 8 and Comparative Examples 1 to 6

[0048] The kinematic viscosity at 30°C of the diluted solutions of synthetic fiber treatment agents of Examples 2 to 8 and Comparative Examples 1 to 6 and the non-volatile fraction thereof was measured in the same manner as that of the diluted solution of a synthetic fiber treatment agent of Example 1. The results are summarized in Table 2.

Test Category 3 (Manufacture and evaluation of synthetic fibers oiled with diluted solution of synthetic fiber treatment agent)

- Example 1

[0049] Polyethylene terephthalate chips having an intrinsic viscosity of 0.64 and a titanium oxide content of 0.2% were dried by a conventional method, then spun at 295°C using an extruder, and discharged from a die and solidified by cooling. Thereafter, the diluted solution of a synthetic fiber treatment agent (P-1) prepared in Test Category 1 was adhered to the running yarn by the guide oiling method using a metering pump so that the proportion of the synthetic fiber treatment agent to the running yarn is 1.0%. The fibers were collected by the guide, wound three times around the first roller heated to 90°C, and taken up at a rate of 1,400 m/min. Then, an 83.3 dtex (75 denier) 36-filament polyester fiber was manufactured by winding three times on a second roller heated to 130°C and rotating at a speed of 4,800 m/min, and stretching by a factor of 3.4 between the first roller and the second roller. The amount of the synthetic fiber treatment agent adhered when the polyester fiber was manufactured, the oil drop at the oiling guide, the spinnability, the yarn quality, and the dyeability were measured and evaluated by the following methods. The results are shown in Table 2.

- Measurement of adhered amount of synthetic fiber treatment agent

[0050] A total of 2 g of the polyester fiber manufactured as described above was precisely weighed and extracted with 10 ml of a mixed solution of n-hexane/ethanol = 7/3 (volume ratio), and the extract was dried for 5 min at 100°C on an aluminum tray that was precisely weighed, and the mass was thereafter measured. The adhered amount of the synthetic fiber treatment agent to the synthetic fiber was determined by following formula 1.

In formula 1,

A represents the weight of the aluminum tray,

B represents the weight of the aluminum tray including the extracted synthetic fiber treatment agent,

S represents the weight of the fiber used for extraction.

- Evaluation of oil drop

[0051] The dropping phenomenon of the diluted solution of a synthetic fiber treatment agent from the oiling guide was visually observed, the number of times the diluted solution was dropped per minute was measured 5 times, and the average value was evaluated according to the following criteria. The average value was rounded off to the nearest whole number.

○○: number of drops is 0,

○: number of drops is 1,

×: number of drops is 2 or more.

- Evaluation of Spinnability

[0052] The number of yarn breaks per ton of yarn when the polyester fiber was manufactured was measured 10 times, and the average value was evaluated according to the following criteria.

○○: number of yarn breaks is less than 0.5,

○: number of yarn breaks is 0.5 times or more and less than 2.0 times,

×: number of yarn breaks is 2.0 times or more.

- Evaluation of Yarn Quality

[0053] The Uster unevenness U% of the manufactured polyester fibers was evaluated at a yarn speed of 200 m/min using an Uster Tester UT-5 manufactured by Uster Technologies AG. The same evaluation was performed 5 times, and the evaluation was performed according to the following criteria from the results of each time.

○○: Uster unevenness U% is less than 1 in all 5 times,

○: Uster unevenness U% is 1 or more in 1 out of 5 times,

×: Uster unevenness U% is 1 or more in 2 or more out of 5 times.

- Evaluation of Dyeability

[0054] A knitted fabric having a diameter of 70 mm and a length of 1.2 m was prepared from the manufactured polyester fiber with a cylindrical knitting machine. The produced knitted fabric was dyed by a high-pressure dyeing method using a disperse dye (trade name Kayalon Polyester Blue EBL-E, manufactured by Nippon Kayaku Co., Ltd.). The dyed knitted fabric was washed with water, reduction-washed, and dried in accordance with a conventional method (for example, Japanese Laid-Open Patent Publication No. 2015-124443), and then attached to an iron cylinder having a diameter of 70 mm and a length of 1 m. The number of deeply dyed portions on the knitted fabric surface was counted with the naked eye and evaluated. The same evaluation was performed 5 times, and the average value of the number of the deeply dyed portion counted each time was evaluated according to the following criteria. The average value was rounded off to the nearest whole number.

○○: there is no deeply dyed portion (0),

○: there are 1 or 2 deeply dyed portions,

×: there are 3 or more deeply dyed portions.

- Examples 2 to 8 and Comparative Examples 1 to 6

[0055] For Examples 2 to 8 and Comparative Examples 1 to 6, the polyester fibers were manufactured, and the adhered amount of the synthetic fiber treatment agent, oil drop, spinnability, yarn quality, and dyeability were evaluated in the same manner as in Example 1. The results are summarized in Table 2.

[0056] As is clear from the results shown in Table 2, according to the present invention, oil drop can be sufficiently prevented by keeping the appropriate viscosity of the high-concentration diluted solution of a synthetic fiber treatment agent. In addition, in the spinning and stretching method in which the yarn is wound more than 0 times and 3 or fewer times around the heating roller, a synthetic fiber having good spinnability and excellent yarn quality and dyeability can be obtained.

Claims

1. A diluted solution of a synthetic fiber treatment agent, comprising:

a synthetic fiber treatment agent including a smoothing agent, a nonionic surfactant, and an antistatic agent; and

a volatile diluent, wherein

where the total content of the synthetic fiber treatment agent and the volatile diluent in the diluted solution is taken as 100% by mass, the proportion of the synthetic fiber treatment agent is 60% by mass or more and less than 100% by mass, and the proportion of the volatile diluent is greater than 0% by mass and equal to or less than 40% by mass,

the diluted solution has a kinematic viscosity at 30°C of greater than 0 mm²/s and less than 80 mm²/s, and

the diluted solution is used in a spinning and stretching step using a spinning and stretching machine equipped with a plurality of heating rollers for stretching a spun yarn, this step being a spinning and stretching method in which the yarn is wound around each heating roller more than 0 times and 3 or fewer times.

2. The diluted solution of a synthetic fiber treatment agent according to claim 1, wherein the kinematic viscosity at 30°C of a non-volatile fraction in the diluted solution is 10 to 70 mm²/s.

3. The diluted solution of a synthetic fiber treatment agent according to claim 1 or 2, wherein the kinematic viscosity at 30°C of the diluted solution is 10 to 70 mm²/s.

4. The diluted solution of a synthetic fiber treatment agent according to any one of claims 1 to 3, wherein the kinematic viscosity at 30°C of the diluted solution is 20 to 65 mm²/s.

5. The diluted solution of a synthetic fiber treatment agent according to any one of claims 1 to 4, wherein where the total content of the synthetic fiber treatment agent and the volatile diluent in the diluted solution is taken as 100% by mass, the proportion of the synthetic fiber treatment agent is 65% to 98% by mass, and the proportion of the volatile diluent is 2% to 35% by mass.

6. The diluted solution of a synthetic fiber treatment agent according to claim 5, wherein the proportion of the synthetic fiber treatment agent is 70% to 95% by mass, and the proportion of the volatile diluent is 5% to 30% by mass.

7. The diluted solution of a synthetic fiber treatment agent according to claim 5, wherein the proportion of the synthetic fiber treatment agent is 75% to 92% by mass, and the proportion of the volatile diluent is 8% to 25% by mass.

8. The diluted solution of a synthetic fiber treatment agent according to any one of claims 1 to 7, wherein the volatile diluent contains water.

9. The diluted solution of a synthetic fiber treatment agent according to any one of claims 1 to 8, wherein the smoothing agent contains a fatty acid ester having a total of 24 to 32 carbon atoms in a molecule.

10. The diluted solution of a synthetic fiber treatment agent according to any one of claims 1 to 9, wherein the antistatic agent contains at least one compound selected from a fatty acid salt, an organic phosphate, an organic sulfonate, an amphoteric compound, and a quaternary ammonium salt.

11. The diluted solution of a synthetic fiber treatment agent according to any one of claims 1 to 10, wherein where the total content of the smoothing agent, nonionic surfactant, and antistatic agent in the synthetic fiber treatment agent is taken as 100% by mass, the proportion of the smoothing agent is 30% to 80% by mass, the proportion of the nonionic surfactant is 5% to 70% by mass, and the proportion of the antistatic agent is 1% to 20% by mass.

12. A method for manufacturing a synthetic fiber, comprising:

a step of adhering the diluted solution of a synthetic fiber treatment agent according to any one of claims 1 to 11 to a synthetic fiber yarn so that the proportion of the synthetic fiber treatment agent to the yarn is 0.1 % to 20% by mass, and

a spinning and stretching step using a spinning and stretching machine equipped with a plurality of heating rollers for stretching a spun yarn, wherein the yarn is wound around each heating roller more than 0 times and 3 or fewer times.