Synthetic fiber treatment agent and use thereof

Abstract

The purpose of the present invention is to provide a synthetic fiber treatment agent having excellent low temperature stability.　This synthetic fiber treatment agent contains a smoothing component (A) and a surfactant (B). The iodine value of nonvolatile components of the treatment agent is 5-100, the strong acid value of the nonvolatile components of the treatment agent is 0.0-0.3 mg KOH / g, and the kinematic viscosity of the nonvolatile components of the treatment agent is more than 60 mm2 / s to not more than 1000 mm2 / s at 25°C. It is preferable that the surfactant (B) contains an anionic surfactant (B1), the anionic surfactant (B1) includes an anionic surfactant (B1-1) having sulfur atoms, and the anionic surfactant (B1-1) having sulfur atoms includes at least one selected from an organic sulfonic acid compound represented by general formula (2) and an organic sulfonic acid compound represented by general formula (3).

Description

Treatment agents for synthetic fibers and their applications 【0001】 This invention relates to a treatment agent for synthetic fibers and its use. 【0002】 In the manufacturing of synthetic fibers for industrial and apparel use, fiber treatment agents are applied using lubrication rollers and guides, and from the viewpoint of uniform adhesion, treatment agents highly diluted with low viscosity paraffin or water have been used. However, in recent years, from the viewpoint of environmental release and running costs, there has been an increasing adoption of methods that reduce the amount of low viscosity paraffin or water used and apply highly concentrated treatment agents. However, with conventional synthetic fiber treatment agents (Patent Document 1), when applying highly concentrated treatment agents by reducing the amount of low viscosity paraffin or water used, scum accumulates in the lubrication equipment, eventually preventing proper lubrication and causing synthetic fiber production to stop. 【0003】 Japanese Patent No. 6533002 【0004】 An investigation into the cause revealed that the poor low-temperature stability of the synthetic fiber treatment agent was detrimental to stable production. Therefore, the object of the present invention is to provide a synthetic fiber treatment agent with excellent low-temperature stability. 【0005】 As a result of diligent research, the present inventors have found that the problems of the present invention can be solved by using a specific synthetic fiber treatment agent, and have arrived at the present invention. That is, the synthetic fiber treatment agent of the present invention (hereinafter sometimes simply referred to as the treatment agent) includes the following embodiments: <1> A synthetic fiber treatment agent containing a smoothing component (A) and a surfactant (B), wherein the iodine value of the nonvolatile content of the treatment agent is 5 to 100, the strong acid value of the nonvolatile content of the treatment agent is 0.0 to 0.3 mgKOH / g, and the kinematic viscosity of the nonvolatile content of the treatment agent is 60 mm at 25°C. ２ / s exceeding 1000mm ２A treatment agent for synthetic fibers having a coefficient of 1 / s or less. <2> The treatment agent for synthetic fibers according to <1>, wherein the surfactant (B) contains an anionic surfactant (B1), the anionic surfactant (B1) contains an anionic surfactant (B1-1) having a sulfur element, and the anionic surfactant (B1-1) having a sulfur element contains at least one selected from an organic sulfonic acid compound represented by the following general formula (2) and an organic sulfonic acid compound represented by the following general formula (3). (In formula (2), a and b are integers greater than or equal to 0, such that a + b = 5 to 17. M is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group.) (In formula (3), c, d, and e are integers of 0 or more that satisfy c + d + e = 4 to 16. M is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group.) <3> The synthetic fiber treatment agent according to claim 2, wherein the anionic surfactant (B1-1) having a sulfur element comprises an organic sulfonic acid compound represented by the general formula (2) and an organic sulfonic acid compound represented by the general formula (3) below. <4> The synthetic fiber treatment agent according to any one of <1> to <3>, wherein the smoothing component (A) comprises an ester component having a structure in which an aliphatic polyhydric alcohol and a fatty acid are ester-bonded. <5> Sulfate ions (SO) detected from the nonvolatile content of the treatment agent by ion chromatography. ４ ２－ A synthetic fiber treatment agent according to any one of <1> to <4>, wherein the content is 0.1 ppm or more and 600 ppm or less. <6> Chloride ions (Cl) detected from the nonvolatile content of the treatment agent by ion chromatography. － ) A synthetic fiber treatment agent according to any one of <1> to <5>, wherein the content is 0.1 ppm or more and 500 ppm or less. <7> Phosphate ions (PO) detected from the nonvolatile content of the treatment agent by ion chromatography. ４ ３－) A synthetic fiber treatment agent according to any one of <1> to <6>, wherein the content is 0.1 ppm or more and 200 ppm or less. <8> A synthetic fiber treatment agent according to any one of <1> to <7>, wherein the surfactant (B) contains a nonionic surfactant. <9> A synthetic fiber treatment agent according to any one of <1> to <8>, further containing an antioxidant. <10> A synthetic fiber obtained by applying a synthetic fiber treatment agent according to any one of <1> to <9> to a raw synthetic fiber. <11> A method for producing a synthetic fiber, comprising the step of applying a synthetic fiber treatment agent according to any one of <1> to <9> to a raw synthetic fiber. <12> A fiber structure containing the synthetic fiber according to <10>. 【0006】 The synthetic fiber treatment agent of the present invention exhibits excellent low-temperature stability. As a result, it offers excellent productivity of synthetic fibers. The manufacturing method of the present invention uses a synthetic fiber treatment agent with excellent low-temperature stability, thus offering excellent productivity of synthetic fibers. The synthetic fibers of the present invention are of superior quality. The fiber structures of the present invention are of superior quality. 【0007】 The synthetic fiber treatment agent of the present invention contains a smoothing component (A) and a surfactant (B), and the iodine value, strong acid value, and kinematic viscosity of the nonvolatile components of the treatment agent are within a specific range. A detailed explanation follows below. 【0008】 [Smoothing component (A)] The treatment agent of the present invention contains a smoothing component (A). Examples of smoothing component (A) include known smoothing components commonly used as synthetic fiber treatment agents, such as: 1) ester compounds having a structure in which an aliphatic monohydric alcohol and a fatty acid are ester-bonded (A1); 2) ester compounds having a structure in which an aliphatic polyhydric alcohol and a fatty acid are ester-bonded (A2); 3) ester compounds having a structure in which an aliphatic monohydric alcohol and an aliphatic polycarboxylic acid are ester-bonded (A3); 4) aromatic ester compounds having an aromatic ring in the molecule (A4); 5) sulfur-containing ester compounds (A5); and 6) mineral oil (A6). One or more types of smoothing component (A) can be used. 【0009】1) Ester compound (A1) The ester compound (A1) is a compound having a structure in which an aliphatic monohydric alcohol and a fatty acid (aliphatic monobasic carboxylic acid) are ester-bonded, and is a compound having no polyoxyalkylene group in the molecule. One or more kinds of ester compounds (A1) can be used. The ester compound (A1) is not particularly limited, but is preferably a compound represented by the following general formula (1). 【0010】 (In the formula, R １ represents an alkyl group or an alkenyl group having 4 to 24 carbon atoms, and R ２ represents an alkyl group or an alkenyl group having 6 to 24 carbon atoms.) 【0011】 In formula (1), the number of carbon atoms of R １ is not particularly limited, but from the viewpoint of smoothness, 6 to 22 is preferable. The upper limit of the number of carbon atoms is more preferably 20, further preferably 18, and particularly preferably 16. On the other hand, the lower limit of the number of carbon atoms is more preferably 8, further preferably 10, and particularly preferably 12. Also, for example, 8 to 20 is more preferable, and 10 to 18 is further preferable. R １ may be either an alkyl group or an alkenyl group, but from the viewpoint of excellent heat resistance, an alkyl group is preferable. 【0012】 In formula (1), the number of carbon atoms of R ２ is not particularly limited, but from the viewpoint of smoothness, 6 to 22 is preferable. The upper limit of the number of carbon atoms is more preferably 20, further preferably 18, and particularly preferably 16. On the other hand, the lower limit of the number of carbon atoms is more preferably 8, further preferably 10, and particularly preferably 12. Also, for example, 8 to 20 is more preferable, and 10 to 18 is further preferable. R ２ may be either an alkyl group or an alkenyl group, but from the viewpoint of strong oil film strength and difficulty in generating flyers, an alkenyl group is preferable. 【0013】The ester compound (A1) is not particularly limited, but examples include 2-decyltetradecanoyl elusinate, 2-decyltetradecanoyl oleate, 2-octyldodecyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, butyl palmitate, butyl stearate, butyl oleate, 2-ethylhexyl oleate, lauryl oleate, isotridecyl stearate, hexadecyl stearate, isostearyl oleate, oleyl octanoate, oleyl laurate, oleyl palmitate, oleyl stearate, oleyl oleate, and the like. Among these, 2-decyltetradecanoyl oleate, 2-octyldodecyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, lauryl oleate, isotridecyl stearate, hexadecyl stearate, isostearyl oleate, and oleyl oleate are preferred. 【0014】 Ester compound (A1) can be synthesized and obtained by known methods using commercially available fatty acids and aliphatic monohydric alcohols. 【0015】 2) Ester compound (A2) Ester compound (A2) is a compound having a structure in which an aliphatic polyhydric alcohol and a fatty acid (aliphatic monocarboxylic acid) are ester-bonded, and is a compound that does not have a polyoxyalkylene group in its molecule. One or more types of ester compound (A2) can be used. 【0016】The aliphatic polyhydric alcohol constituting the ester compound (A2) is not particularly limited as long as it is divalent or higher, and one or more types can be used. From the viewpoint of oil film strength, the polyhydric alcohol is preferably trivalent or higher, more preferably trivalent to tetravalent, and even more preferably trivalent. Examples of aliphatic polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanediol, cyclohexanedimethanol, glycerin, trimethylolpropane, pentaerythritol, erythritol, diglycerin, sorbitan, sorbitol, ditrimethylolpropane, dipentaerythritol, triglycerin, tetraglycerin, sucrose, and the like. Among these, glycerin, trimethylolpropane, pentaerythritol, erythritol, diglycerin, sorbitan, sorbitol, ditrimethylolpropane, dipentaerythritol, and sucrose are preferred, glycerin, trimethylolpropane, pentaerythritol, erythritol, diglycerin, and sorbitan are more preferred, and glycerin and trimethylolpropane are even more preferred. 【0017】 The fatty acids constituting the ester compound (A2) may be saturated or unsaturated. There is no particular limit to the number of unsaturated bonds, but one, two, or three are preferred in terms of smoothness and low-temperature stability. There is no particular limit to the number of carbon atoms in the fatty acid, but 8 to 24 are preferred in terms of achieving both oil film strength and smoothness. The upper limit of the number of carbon atoms is more preferably 20, even more preferably 18, and particularly preferably 16. On the other hand, the lower limit of the number of carbon atoms is more preferably 10, even more preferably 12, and particularly preferably 14. Also, for example, 10 to 20 is more preferably, and 12 to 18 is even more preferably. One or more types of fatty acids may be used, and saturated fatty acids and unsaturated fatty acids may be used in combination. 【0018】Examples of fatty acids include butyric acid, crotonic acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, myristoleic acid, pentadecanoic acid, palmitic acid, palmitoleic acid, isocetyl acid, margaric acid, stearic acid, isostearic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linolenic acid, tuberculinostearic acid, arachidic acid, isoeicosacid, gadoleic acid, eicosenoic acid, docosanic acid, isodocosanic acid, erucic acid, tetracosanic acid, isotetracosanic acid, nervonic acid, cerotic acid, montanic acid, and melissic acid. Among these, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, myristoleic acid, pentadecanoic acid, palmitic acid, palmitoleic acid, isocetyl acid, margaric acid, stearic acid, isostearic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linolenic acid, tubercurostearic acid, arachidic acid, isoeicosacic acid, gadoleic acid, eicosenoic acid, docosanic acid, isodocosanic acid, erucic acid, tetracosanic acid, isotetracosanic acid, and nervonic acid are preferred, and capric acid, lauric acid, myristic acid, and myristoleic acid are preferred. Acids, pentadecanoic acid, palmitic acid, palmitoleic acid, isocetyl acid, margaric acid, stearic acid, isostearic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linolenic acid, tuberculinostearic acid, arachidic acid, isoeicosaic acid, gadoleic acid, and eicosenoic acid are more preferred, and lauric acid, myristic acid, myristoleic acid, pentadecanoic acid, palmitic acid, palmitoleic acid, isocetyl acid, margaric acid, stearic acid, isostearic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, and linolenic acid are even more preferred. 【0019】 The ester compound (A2) is a compound having two or more ester bonds in its molecule, but from the viewpoint of spinnability, it is preferable that it is a compound having three or more ester bonds in its molecule, and more preferably a compound having three ester bonds in its molecule. There are no particular limitations on the iodine value of the ester compound (A2). 【0020】The weight-average molecular weight of the ester compound (A2) is preferably 300 to 1200 in terms of smoothness and low smoke emission. The upper limit of the average molecular weight is more preferably 1150, and even more preferably 1100. On the other hand, the lower limit of the average molecular weight is more preferably 500, and even more preferably 600. Also, for example, 300 to 1150 is more preferably, and even more preferably 500 to 1100. The weight-average molecular weight in this invention was calculated using a high-speed gel permeation chromatography apparatus HLC-8220GPC manufactured by Tosoh Corporation, by injecting a sample concentration of 3 mg / cc into separation columns KF-402HQ and KF-403HQ manufactured by Showa Denko K.K., and measuring the peaks with a differential refractive index detector. 【0021】Examples of ester compounds (A2) include trimethylolpropane tricaprylate, trimethylolpropane tricaprinate, trimethylolpropane trilaurate, trimethylolpropane trioleate, trimethylolpropane (laurate, myristylate, palmitate), trimethylolpropane (laurate, myristylate, oleate), trimethylolpropane (tripalme kernel fatty acid ester), trimethylolpropane (coconut fatty acid ester), trimethylolpropane dicaprylate, trimethylolpropane dicaprinate, trimethylolpropane dilaurate, trimethylolpropane dioleate, trimethylolpropane (laurate, myristylate), trimethylolpropane (laurate, oleate), trimethylolpropane (myristylate, oleate), trimethylolpropane (dipalm kernel fatty acid ester), and Examples include limethylolpropane (coconut fatty acid ester), coconut oil, rapeseed oil, palm oil, palm olein oil, sunflower oil, sesame oil, soybean oil, flaxseed oil, blended salad oil, glycerin trilaurate, glycerin trioleate, glycerin triisostearate, glycerin dioleate, glycerin monolaurate, diglycerin dioleate, sorbitan trioleate, sorbitan (laurate, myristylate, oleate), sorbitan dilaurate, sorbitan monooleate, pentaerythritol tetracaprylate, pentaerythritol tetracaprinate, pentaerythritol tetralaurate, erythritol tetralaurate, pentaerythritol (tetrapalm kernel fatty acid ester), pentaerythritol (tetracoconut fatty acid ester), erythritol trioleate, erythritol dipalmitate, 1,6-hexanediol dioleate, etc. 【0022】The ester compound (A2) may be one synthesized by a known method using commercially available fatty acids and aliphatic polyhydric alcohols. Alternatively, natural esters obtained from natural sources such as fruits, seeds, or flowers that satisfy the composition of ester compound (A2) may be used as is, or, if necessary, natural esters may be purified by a known method, or further purified esters may be separated and re-purified using a known method based on the difference in melting points. Alternatively, esters obtained by transesterifying two or more natural esters (fats and oils) may be used. 【0023】 3) Ester Compound (A3) Ester compound (A3) is a compound having a structure in which an aliphatic monohydric alcohol and an aliphatic polyhydric carboxylic acid are ester-bonded, and is a compound that does not have a polyoxyalkylene group in its molecule. One or more types of ester compound (A3) can be used. 【0024】 The aliphatic monohydric alcohol constituting the ester compound (A3) is not particularly limited, and one or more types may be used. The aliphatic monohydric alcohol may be saturated or unsaturated. There is no particular limit to the number of unsaturated bonds, but three or fewer is preferred in terms of smoothness. The carbon number of the aliphatic monohydric alcohol is preferably 8 to 24 from the viewpoint of smoothness and oil film strength. The upper limit of the carbon number is more preferably 22, even more preferably 20, and particularly preferably 18. On the other hand, the lower limit of the carbon number is more preferably 12, even more preferably 14, and particularly preferably 16. Also, for example, 12 to 22 is more preferred, and 14 to 20 is even more preferred. One or more types of aliphatic monohydric alcohols may be used, and saturated aliphatic monohydric alcohols and unsaturated aliphatic monohydric alcohols may be used in combination. 【0025】Examples of aliphatic monohydric alcohols include octyl alcohol, isooctyl alcohol, lauryl alcohol, myristyl alcohol, myristrail alcohol, cetyl alcohol, isocetyl alcohol, palmitrail alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, vaccenyl alcohol, gadleyl alcohol, arachidyl alcohol, isoicosanyl alcohol, eicosenoyl alcohol, behenyl alcohol, isodocosanyl alcohol, erukanyl alcohol, lignocerinyl alcohol, isotetracosanyl alcohol, nerbonyl alcohol, cerotinyl alcohol, montanyl alcohol, and merisinyl alcohol. Among these, octyl alcohol, isooctyl alcohol, lauryl alcohol, myristyl alcohol, myristyl alcohol, cetyl alcohol, isocetyl alcohol, palmitrail alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, baxenyl alcohol, gadleyl alcohol, arachidyl alcohol, isoicosanyl alcohol, eicosenoyl alcohol, behenyl alcohol, isodocosanyl alcohol, erukanyl alcohol, lignocerinyl alcohol, isotetracosanyl alcohol, and nerbonyl alcohol are preferred, myristrail alcohol, palmitrail alcohol, oleyl alcohol, elaidyl alcohol, baxenyl alcohol, gadleyl alcohol, eicosenoyl alcohol, erukanyl alcohol, and nerbonyl alcohol are more preferred, and oleyl alcohol, elaidyl alcohol, baxenyl alcohol, gadleyl alcohol, eicosenoyl alcohol, and erukanyl alcohol are even more preferred. 【0026】The aliphatic polycarboxylic acid constituting the ester (A3) is not particularly limited as long as it is divalent or higher, and one or more types can be used. The aliphatic polycarboxylic acid used in the present invention does not include sulfur-containing polycarboxylic acids such as thiodipropionic acid. The valency of the aliphatic polycarboxylic acid is preferably divalent. Similarly, it is preferable that the molecule does not contain a hydroxyl group. Examples of aliphatic polycarboxylic acids include citric acid, isocitric acid, malic acid, aconitic acid, oxaloacetate, oxalosuccinic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Among these, aconitic acid, oxaloacetate, oxalosuccinic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid are preferred, and fumaric acid, maleic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid are more preferred. 【0027】 Examples of ester compounds (A3) include dioctyl adipic acid, dilauryl adipic acid, dioleyl adipic acid, diisocetyl adipic acid, dioctyl sebacate, dilauryl sebacate, dioleyl sebacate, and diisocetyl sebacate. 【0028】 Ester compounds (A3) are compounds having two or more ester bonds in their molecule. There are no particular limitations on the iodine value of ester compounds (A3). 【0029】 The weight-average molecular weight of the ester compound (A3) is not particularly limited, but is preferably 500 to 1000 in terms of smoothness and low smoke generation. The upper limit of the average molecular weight is more preferably 800, and even more preferably 700. On the other hand, the lower limit of the average molecular weight is more preferably 600, and even more preferably 650. Also, for example, is more preferably 500 to 800, and even more preferably 500 to 700. 【0030】 Ester compounds (A3) can generally be synthesized and obtained using commercially available aliphatic monohydric alcohols and aliphatic polycarboxylic acids by known methods. 【0031】4) Aromatic ester compounds (A4) Aromatic ester compounds (A4) are ester compounds having at least one aromatic ring in their molecule. Specifically, examples include ester compounds (A4-1) having a structure in which an aromatic carboxylic acid and an alcohol are ester-bonded, and ester compounds (A4-2) having a structure in which an aromatic alcohol and a carboxylic acid are ester-bonded. Furthermore, aromatic ester compounds (A4) are compounds that do not have a polyoxyalkylene group in their molecule. One or more aromatic ester compounds (A4) can be used. 【0032】 The aromatic carboxylic acid constituting the ester compound (A4-1) may be a monocarboxylic acid or a polycarboxylic acid. One or more types may be used. Examples of aromatic carboxylic acids include benzoic acid, toluic acid, naphthoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, melitic acid, cinnamic acid, trimellitic acid, and pyromellitic acid. Among these, trimellitic acid, phthalic acid, isophthalic acid, and terephthalic acid are preferred, with trimellitic acid being even more preferred. 【0033】 The alcohol constituting the ester compound (A4-1) may be a monohydric alcohol or a polyhydric alcohol. It may also be an aliphatic alcohol, an alicyclic alcohol, or an aromatic alcohol. One or more monohydric alcohols can be used. Among these, monohydric alcohols are preferred, and aliphatic monohydric alcohols are even more preferred. 【0034】Examples of monohydric alcohols include alkylbenzene alcohols, dialkylbenzene alcohols, octyl alcohol, isooctyl alcohol, lauryl alcohol, myristyl alcohol, myristrail alcohol, cetyl alcohol, isocetyl alcohol, palmitrail alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, baxenyl alcohol, gadleyl alcohol, arachidyl alcohol, isoicosanyl alcohol, eicosenoyl alcohol, behenyl alcohol, isodocosanyl alcohol, erukanyl alcohol, lignocerinyl alcohol, isotetracosanyl alcohol, nerbonyl alcohol, cerothinyl alcohol, montanyl alcohol, and merisinyl alcohol. Examples of polyhydric alcohols include aliphatic polyhydric alcohols as described in ester compounds (A2) and aromatic polyhydric alcohols as described in ester compounds (A4-2). 【0035】 The aromatic alcohol constituting the ester compound (A4-2) can be one or more types. Aromatic polyhydric alcohols are preferred, and aromatic trihydric alcohols are more preferred. Examples of aromatic alcohols include aromatic monohydric alcohols such as alkylbenzene alcohols, dialkylbenzene alcohols, and aromatic polyhydric alcohols such as bisphenol A, bisphenol Z, and 1,3,5-trihydroxymethylbenzene. Among these, bisphenol A, bisphenol Z, and 1,3,5-trihydroxymethylbenzene are preferred, and 1,3,5-trihydroxymethylbenzene is more preferred. 【0036】 The carboxylic acid constituting the ester compound (A4-2) may be either an aliphatic carboxylic acid or an aromatic carboxylic acid. It may also be either a monohydric carboxylic acid or a polyhydric carboxylic acid. One or more types may be used. Among these, monohydric carboxylic acids are preferred, and fatty acids are even more preferred. Fatty acids are preferably saturated from the viewpoint of persistence. Fatty acids may be linear or branched. 【0037】Examples of monovalent carboxylic acids include alkylbenzene carboxylic acids, dialkylbenzene carboxylic acids, butyric acid, crotonic acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, myristoleic acid, pentadecylic acid, palmitic acid, palmitoleic acid, isocetyl acid, margaric acid, stearic acid, isostearic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linolenic acid, tubercurostearic acid, arachidic acid, isoeicosanoic acid, gadelic acid, eicosenoic acid, behenic acid, isodocosanoic acid, erucic acid, lignoceric acid, isotetracosanoic acid, nervonic acid, cerotic acid, montanic acid, and melissic acid. Examples of polyvalent carboxylic acids include aliphatic polyvalent carboxylic acids as described in ester compounds (A3) and aromatic polyvalent carboxylic acids as described in ester compounds (A4-1). 【0038】5) Sulfur-containing ester compound (A5) The sulfur-containing ester compound is not particularly limited, but is preferably at least one selected from diester compounds of thiodipropionic acid and aliphatic alcohol and monoester compounds of thiodipropionic acid and aliphatic alcohol. The sulfur-containing ester compound is a component that has antioxidant ability. By using the sulfur-containing ester compound, the heat resistance of the treatment agent can be increased. One or more sulfur-containing ester compounds can be used. The weight-average molecular weight of the sulfur-containing ester compound is not particularly limited, but is preferably 400 to 1000 in terms of smoothness and low smoke generation. The upper limit of the molecular weight is more preferably 900 and even more preferably 800. On the other hand, the lower limit of the molecular weight is more preferably 500 and even more preferably 600. Also, for example, is more preferably 500 to 900 and even more preferably 600 to 800. The aliphatic alcohol constituting the sulfur-containing ester compound may be saturated or unsaturated. Furthermore, the aliphatic alcohol may have a linear or branched structure, but a branched structure is preferred. The number of carbon atoms in the aliphatic alcohol is preferably 8 to 24, more preferably 12 to 24, and even more preferably 16 to 24. Examples of aliphatic alcohols include octyl alcohol, 2-ethylhexyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, isocetyl alcohol, oleyl alcohol, and isostearyl alcohol, among which oleyl alcohol and isostearyl alcohol are preferred. The sulfur-containing ester compound may be a mixture of a diester compound of thiodipropionic acid and an aliphatic alcohol (simply referred to as a diester in this paragraph) and a monoester compound of thiodipropionic acid and an aliphatic alcohol (simply referred to as a monoester in this paragraph). In this case, the weight ratio of the diester to the monoester is preferably 100 / 0 to 70 / 30 in terms of smoothness and low smoke generation. The upper limit of the weight ratio is more preferably 99.5 / 0.5, and even more preferably 99 / 1. On the other hand, the lower limit of the weight ratio is more preferably 75 / 25, and even more preferably 80 / 20. Also, for example, 100 / 0 to 75 / 25 is more preferably, and 100 / 0 to 80 / 20 is even more preferably. 【0039】6) Mineral oil (A6) The synthetic fiber treatment agent of the present invention may also contain mineral oil as a smoothing component other than those mentioned above. The mineral oil referred to here is not a low-viscosity diluent used to dilute the treatment agent, but is included in the non-volatile components. There are no particular limitations on the mineral oil, but examples include machine oil, spindle oil, liquid paraffin, etc. One or more types of mineral oil may be used. The viscosity of the mineral oil at 30°C is preferably 100 to 500 sec. 【0040】 As for the smoothing component (A), it is preferable to use a purified product from which catalysts and other impurities have been removed, from the viewpoint of improving heat resistance and obtaining a clear treatment agent. 【0041】 [Surfactant (B)] The treatment agent of the present invention contains a surfactant (B). Examples of surfactant (B) include anionic surfactants (B1), nonionic surfactants (B2), cationic surfactants, amphoteric surfactants, etc., and there are no particular limitations as long as it is a surfactant other than the smoothing agent mentioned above. However, in terms of antistatic properties, it is preferable to include at least one selected from nonionic surfactants, anionic surfactants, and cationic surfactants, more preferable to include at least one selected from nonionic surfactants and anionic surfactants, and even more preferable to include nonionic surfactants and anionic surfactants. 【0042】 [Anionic surfactant (B1)] There are no particular limitations on the anionic surfactant (B1), but examples include anionic surfactants having a sulfur element (B1-1), organophosphate ester compounds (B1-2), fatty acid soaps (B1-3), etc. However, in terms of antistatic properties and emulsifying properties, it is preferable to include at least one selected from anionic surfactants having a sulfur element (B1-1), organophosphate ester compounds (B1-2), and fatty acid soaps (B1-3), more preferably including an anionic surfactant having a sulfur element (B1-1), and even more preferably including an anionic surfactant having a sulfur element (B1-1) and organophosphate ester compounds (B1-2). 【0043】[Anionic surfactant containing a sulfur element (B1-1)] The treatment agent of the present invention preferably contains an anionic surfactant containing a sulfur element (B1-1) in terms of antistatic properties, emulsifying properties, and compatibility. The anionic surfactant containing a sulfur element (B1-1) is not particularly limited, but examples include organic sulfonic acid compounds, alkyl sulfate esters, alkyl ether sulfate esters, etc., and it is preferable to include organic sulfonic acid compounds in terms of heat resistance. 【0044】 Examples of organic sulfonic acid compounds include organic sulfonic acid compounds represented by general formula (2) and organic sulfonic acid compounds represented by general formula (3). In terms of heat resistance, it is preferable to include at least one selected from the organic sulfonic acid compounds represented by general formula (2) and the organic sulfonic acid compounds represented by general formula (3), and it is more preferable to include the organic sulfonic acid compounds represented by general formula (2) and the organic sulfonic acid compounds represented by general formula (3). 【0045】 (In formula (2), a and b are integers greater than or equal to 0, such that a + b = 5 to 17. M is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group.) 【0046】 (In formula (3), c, d, and e are integers greater than or equal to 0, satisfying c + d + e = 4 to 16. M is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group.) 【0047】 The organic sulfonic acid compound represented by formula (2) is a monosulfonic acid compound having one sulfonic acid group in its molecule. The organic sulfonic acid compound represented by general formula (2) may be used alone or in combination of two or more types. In general formula (2), a and b are integers of 0 or greater that satisfy a + b = 5 to 17. There are no particular limitations on a + b, but 6 to 17 is preferred in terms of antistatic properties and heat resistance. The upper limit of a + b is more preferably 16, and even more preferably 15. On the other hand, the lower limit of a + b is more preferably 7, and even more preferably 8. Also, for example, 7 to 16 is more preferably, and even more preferably 8 to 15. 【0048】In formula (2), M is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group. Examples of alkali metals include lithium, sodium, potassium, etc. Examples of ammonium groups and organic amine groups include NR ａ R ｂ R ｃ R ｄ The group shown by R can be listed. ａ , R ｂ , R ｃ and R ｄ These are, independently, a hydrogen atom, an alkyl group, an alkenyl group, and a polyoxyalkylene group. The number of carbon atoms in the alkyl group and alkenyl group is preferably 1 to 24, more preferably 1 to 20, and even more preferably 1 to 18. The polyoxyalkylene group is "-(A １ O) ｍ Indicated by "H", (A １ O) ｍ This is the same as that shown in general formula (3). 【0049】 NR ａ R ｂ R ｃ R ｄThe groups represented by include, for example, ammonium group, methylammonium group, ethylammonium group, propylammonium group, butylammonium group, hexylammonium group, octylammonium group, dimethylammonium group, diethylammonium group, dipropylammonium group, dibutylammonium group, dihexylammonium group, dioctylammonium group, trimethylammonium group, triethylammonium group, tripropylammonium group, tributylammonium group, trihexylammonium group, trioctylammonium group, tetramethylammonium group, tetraethylammonium group, tetrapropylammonium group, tetrabutylammonium group, tetrahexylammonium group, tetraoctylammonium group, ethyltrimethylammonium group, propyltrimethylammonium group, butyltrimethylammonium group, hexyltrimethylammonium group, octyltrimethylammonium group, methanolammonium group, ethanolammonium group, propanolammonium group, butanolammonium group, hexanolammonium group, octanolammonium group, di Methanolammonium group, diethanolammonium group, dipropanolammonium group, dibutanolammonium group, dihexanolammonium group, dioctanolammonium group, trimethanolammonium group, triethanolammonium group, tripropanolammonium group, tributanolammonium group, trihexanolammonium group, trioctanolammonium group, (EO6) butylaminoether group, (EO6) hexylaminoether group, (EO6) octylaminoether group, (EO6) decylaminoether group, (EO6) Laurylamino ether group, (EO6) Tetradecylamino ether group, (EO6) Hexadecylamino ether group, (EO6) Oleylamino ether group, (EO6) Stearylamino ether group, (EO6) Gadleylamino ether group, (EO6) Tetracosylamino ether group, (EO10) Oleylamino ether group, (EO10) Oleylamino ether / erucate, (EO3) Laurylamino ether group, (EO3) Laurylamino ether group, (EO7) Laurylamino ether group, (EO15) Oleylamino ether group,Examples include (PO3,EO5) stearylaminoether groups and (PO5,EO3) stearylaminoether groups. 【0050】 The organic sulfonic acid compound represented by general formula (3) is a disulfonic acid compound having two sulfonic acid groups in its molecule. By using the organic sulfonic acid compound represented by general formula (2) and the organic sulfonic acid compound represented by general formula (3) in combination with the smoothing component (A), lint, thread breakage, and roll soiling can be dramatically reduced. The organic sulfonic acid compound represented by general formula (3) may be used alone or in combination of two or more types. 【0051】 In formula (3), c, d, and e are integers greater than or equal to 0, satisfying c + d + e = 4 to 16. There are no particular limitations on c + d + e, but 5 to 16 is preferred in terms of antistatic properties and heat resistance. The upper limit of c + d + e is more preferably 15, and even more preferably 14. On the other hand, the lower limit of c + d + e is more preferably 6, and even more preferably 7. For example, 6 to 15 is more preferred, and even more preferably 7 to 14. M is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group. Details regarding M are the same as those for M described in general formula (2). 【0052】 The weight ratio ((2) / (3)) of the organic sulfonic acid compound represented by general formula (2) to the organic sulfonic acid compound represented by general formula (3) is not particularly limited, but from the viewpoint of compatibility of the treatment agent for synthetic fibers, 50 / 50 to 99 / 1 is preferred. The upper limit of the weight ratio is more preferably 98 / 2, and even more preferably 97 / 3. On the other hand, the lower limit of the weight ratio is more preferably 70 / 30, and even more preferably 80 / 20. Also, for example, 70 / 30 to 99 / 1 is more preferred, and even more preferably 80 / 20 to 98 / 2. 【0053】Raw materials containing organic sulfonic acid compounds represented by general formula (2) and / or general formula (3) often contain inorganic impurities, namely sodium sulfate and / or sodium chloride, due to their manufacturing process. The ratio of sodium sulfate and sodium chloride contained in these raw materials can be calculated from the weight percentages of sulfate ions and chloride ions detected from the raw materials by ion chromatography. In order to achieve the effects of the present invention, it is preferable to use raw materials containing organic sulfonic acid compounds represented by general formula (2) and / or general formula (3) with reduced amounts of sodium sulfate and sodium chloride in the treatment agent of the present invention. Specifically, it is preferable to use raw materials in which the weight percentage of sulfate ions detected by ion chromatography is 5000 ppm or less and the weight percentage of chloride ions is 5000 ppm or less, relative to the total amount of organic sulfonic acid compounds represented by general formula (2) and general formula (3). 【0054】 There are no particular limitations on the method for reducing inorganic impurities such as sodium sulfate and sodium chloride from a raw material containing an organic sulfonic acid compound represented by general formula (2) and / or an organic sulfonic acid compound represented by general formula (3), and known methods can be employed. For example, if the raw material contains sodium sulfate, one method is to add an alcohol such as methanol, ethanol, or propanol, or a solvent such as water, to the raw material to precipitate and separate the inorganic substances such as sodium sulfate. If the raw material contains sodium chloride, one method is to remove the sodium chloride contained in the raw material using an ion exchange membrane or to adsorb it using an ion exchange resin. 【0055】 [Organophosphate ester compound (B1-2) The treatment agent of the present invention preferably further contains an organic phosphate ester compound (B1-2) in addition to the above-mentioned smoothing component (A) and an anionic surfactant having a sulfur element (B1-1), in order to reduce fluffiness. There are no particular limitations on the organic phosphate ester compound (B1-2), but in terms of antistatic properties and emulsifying properties, it is preferably at least one selected from the compounds represented by general formula (4) and the compounds represented by general formula (5). 【0056】 (In formula (4), R ３ A is a hydrocarbon group having 6 to 24 carbon atoms. １ O is an oxyalkylene group having 2 to 4 carbon atoms, m is an integer from 0 to 15, and n is an integer from 1 to 2. １ (This is a hydrogen atom, alkali metal, ammonium group, or organic amine group.) 【0057】 (In formula (5), R ３ A is a hydrocarbon group having 6 to 24 carbon atoms. １ O is an oxyalkylene group having 2 to 4 carbon atoms, and m is an integer from 0 to 15. １ This is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group. Q １ M １ or R ３ O(A １ O) ｍ (Y is either 1 or 2.) 【0058】 In general formulas (4) and (5), R ３ A is a hydrocarbon group having 6 to 24 carbon atoms. １ O is an oxyalkylene group having 2 to 4 carbon atoms, m is an integer from 0 to 15, and n is an integer from 1 to 2. １ This is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group. Q １ M １ or R ３ O(A １ O) ｍ Therefore, Y is either 1 or 2. 【0059】 R ３ Examples of hydrocarbon groups include alkyl groups and alkenyl groups. ３ The carbon number is preferably 8 to 24 in terms of antistatic properties and emulsifying properties. The upper limit of the carbon number is more preferably 22, and even more preferably 20. On the other hand, the lower limit of the carbon number is more preferably 10, and even more preferably 12. Also, for example, 10 to 22 is more preferably, and even more preferably 12 to 20. ３ The number of carbon atoms may have a distribution, R ３It may be linear or branched, and may be saturated or unsaturated. １ O is an oxyalkylene group having 2 to 4 carbon atoms. m, which is the number of repeating oxyalkylene units, is an integer from 0 to 15, preferably 0 to 10, more preferably 0 to 3, and particularly preferably m is 0, meaning no polyoxyalkylene group is contained. (A １ O) ｍ A polyoxyalkylene group having 50 mol% or more of oxyethylene units as oxyalkylene units is preferred. 【0060】 In general formulas (4) and (5), n is an integer between 1 and 2. When n = 2, the two organic groups [R ３ O(A １ O) ｍ ] - may be the same or different. Also, Q １ = R ３ O(A １ O) ｍ In this case, the two organic groups [R] that constitute the compound represented by general formula (5) ３ O(A １ O) ｍ The ]- may be the same or different. 【0061】 In general formulas (4) and (5), M １ NR is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group. Examples of alkali metals include lithium, sodium, potassium, etc. Examples of ammonium groups and organic amine groups include NR ａ R ｂ R ｃ R ｄ The group shown can be listed as follows: NR ａ R ｂ R ｃ R ｄ The group represented by is the same as M explained in the section on the organic sulfonic acid compound represented by general formula (2). 【0062】The organic phosphate ester compound (B1-2) is a mixture containing the organic phosphate ester compound (B1-2a) represented by n=1 in general formula (4) and the organic phosphate ester compound (B1-2b) represented by n=2 in general formula (4), or the organic phosphate ester compound (B1-2a), (B1-2b) and the organic phosphate ester compound (B1-2a), (B1-2b) and the organic phosphate ester compound (B1-2a), (B1-2b) represented by Y=1, Q in general formula (5). １ = R ３ O(A １ O) ｍ It is preferable that the mixture contains an organic phosphate ester compound (B1-2c) represented by the formula (5). These mixtures are characterized by Y=1 and Q １ = May contain an organic phosphate ester compound (B1-2d) represented by a hydrogen atom. 【0063】 The integral ratio of P-nucleus (%) of organic phosphate ester compounds (B1-2a), (B1-2b), (B1-2c), and (B1-2d), as well as inorganic phosphate, is: ３１It can be calculated from the integral value of the peaks originating from each phosphorus atom in P-NMR. The P-nuclear integral ratio (%) refers to the calculation where the sum of the integral values ​​of the organic phosphate ester compounds (B1-2a), (B1-2b), (B1-2c), (B1-2d) and inorganic phosphoric acid is set to 100%. Inorganic phosphoric acid will be discussed later. The P-nuclear integral ratio (%) of the organic phosphate ester compound (B1-2a) is not particularly limited, but 25 to 85% is preferred. The upper limit of this integral ratio is more preferably 80%, and even more preferably 70%. On the other hand, the lower limit of this integral ratio is more preferably 35%, and even more preferably 40%. For example, 35 to 80% is more preferred, and even more preferably 40 to 70%. The P-nuclear integral ratio (%) of the organic phosphate ester compound (B1-2b) is not particularly limited, but 15 to 65% is preferred. The upper limit of this integral ratio is more preferably 60%, and even more preferably 55%. On the other hand, the lower limit of the integral ratio is more preferably 20%, and even more preferably 25%. Also, for example, 20-60% is more preferable, and even more preferably 25-55%. The P-nucleus integral ratio (%) of the organophosphate ester compound (B1-2c) is not particularly limited, but preferably 0-50%. The upper limit of the integral ratio is more preferably 45%, and even more preferably 40%. On the other hand, the lower limit of the integral ratio is more preferably 0.1%, and even more preferably 0.2%. Also, for example, 0-45% is more preferable, and even more preferably 0-40%. The P-nucleus integral ratio (%) of the organophosphate ester compound (B1-2d) is not particularly limited, but preferably 0-7%. The upper limit of the integral ratio is more preferably 6%, and even more preferably 5%. On the other hand, the lower limit of the integral ratio is more preferably 0.1%, and even more preferably 0.2%. Also, for example, 0-6% is more preferable, and even more preferably 0-5%. The integral ratio of the phosphorus (P) of inorganic phosphoric acid (%) is not particularly limited, but is preferably 0 to 10%. The upper limit of the integral ratio is more preferably 9%, and even more preferably 8%. On the other hand, the lower limit of the integral ratio is more preferably 0.1%, and even more preferably 0.2%. Also, for example, 0 to 9% is more preferably, and even more preferably 0 to 8%. The integral ratio of the P in this invention is determined by the method described in the examples. 【0064】There are no particular limitations on the method for producing the organophosphate ester compound (B1-2), and known methods can be employed. For example, the method for producing the organophosphate ester compound (B1-2) is R ３ O(A １ O) ｍ Organic hydroxyl compounds represented by H and phosphoric anhydride P ２ O ５ The method includes step (I) of reacting with to obtain a reactant. In step (I), inorganic phosphoric acid or water may also be added to the reaction. The method for producing the organic phosphate ester compound (B1-2) may include step (II) of adding water to the reactant after step (I) to hydrolyze it. By including step (II), the ratio of organic phosphate ester compounds (B1-2c) and (B1-2d) contained in the organic phosphate ester compound (B1-2) can be adjusted. The amount of water added to the reactant is preferably 0.01 to 5% by weight, more preferably 0.05 to 4% by weight, and even more preferably 0.1 to 3% by weight, relative to the organic phosphate ester compound (B1-2). The method for producing the organic phosphate ester compound (B1-2) includes step (I) or step (II), followed by M １ The process may include a step (III) of neutralizing with an alkaline compound having [a specific characteristic]. 【0065】 The organic phosphate ester compound (B1-2) contains heavy metal compounds such as arsenic as impurities in anhydrous phosphoric acid or inorganic phosphorus. The treatment agent of the present invention may contain heavy metal compounds such as arsenic. From the viewpoint of the effects on the human body and safety for the environment, the weight percentage of heavy metal compounds in the nonvolatile content of the treatment agent is preferably 0.01% by weight or less, more preferably 0.005% by weight or less, and even more preferably 0.001% by weight or less. 【0066】 When producing organic phosphate ester compounds (B1-2), inorganic phosphoric acid and / or its salts are generated. Therefore, organic phosphate ester compounds (B1-2) contain inorganic phosphoric acid and / or its salts. The ratio of inorganic phosphoric acid and / or its salts is determined by the organic hydroxyl compound and phosphoric anhydride P. ２ O ５ The ratio and reaction conditions can be adjusted accordingly. 【0067】[Fatty Acid Soap (B1-3)] The treatment agent of the present invention may further contain fatty acid soap (B1-3) in addition to the above-mentioned smoothing component (A), anionic surfactant having a sulfur element (B1-1), and organophosphate ester compound (B1-2), from the viewpoint of improving antistatic properties and emulsifying properties. Examples of fatty acid soap include metal salts of fatty acids having 6 to 24 carbon atoms. 【0068】 [Nonionic surfactant (B2)] The treatment agent of the present invention preferably further contains a nonionic surfactant (B2) in addition to the smoothing component (A) and anionic surfactant (B1) described above, in order to impart oil film strength and cohesiveness to the raw yarn and improve spinnability. The nonionic surfactant (B2) refers to the nonionic surfactant excluding the smoothing component (A) described above. One or more types of nonionic surfactants (B2) may be used. 【0069】 Examples of nonionic surfactants (B2) include polyoxyalkylene group-containing hydroxy fatty acid polyhydric alcohol esters (hereinafter sometimes referred to as polyhydroxy esters), esters in which at least one hydroxyl group of a polyhydroxy ester is encapsulated with a fatty acid, polyoxyalkylene polyhydric alcohol ethers, polyoxyalkylene polyhydric alcohol fatty acid esters, polyoxyalkylene aliphatic alcohol ethers, fatty acid esters of polyalkylene glycols, and polyhydric alcohol fatty acid esters. 【0070】 (Polyhydroxyesters, esters in which at least one hydroxyl group of a polyhydroxyester is encapsulated with a fatty acid) Structurally, polyhydroxyesters are esters of a polyoxyalkylene group-containing hydroxy fatty acid and a polyhydric alcohol, and it is preferable that two or more hydroxyl groups of the polyhydric alcohol are esterified. Therefore, polyoxyalkylene group-containing hydroxy fatty acid polyhydric alcohol esters are esters having multiple hydroxyl groups. 【0071】Polyoxyalkylene group-containing hydroxy fatty acids have a structure in which a polyoxyalkylene group is bonded to the hydrocarbon group of a fatty acid via an oxygen atom, with the end of the polyoxyalkylene group that is not bonded to the hydrocarbon group of the fatty acid being a hydroxyl group. Examples of polyhydroxy esters include alkylene oxide adducts of esterified hydroxy fatty acids having 6 to 22 carbon atoms (preferably 16 to 20 carbon atoms) and polyhydric alcohols. 【0072】 Examples of hydroxy fatty acids having 6 to 22 carbon atoms include hydroxycaprylic acid, hydroxycapric acid, hydroxylauric acid, hydroxystearic acid, and ricinoleic acid, with hydroxyoctadecanoic acid and ricinoleic acid being preferred. Examples of polyhydric alcohols include ethylene glycol, glycerin, sorbitol, sorbitan, trimethylolpropane, and pentaerythritol, with glycerin being preferred. Examples of alkylene oxides include alkylene oxides having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, and butylene oxide. 【0073】 The number of moles of alkylene oxide to be added is not particularly limited, but 3 to 60 moles is preferred. The upper limit of this number of moles is more preferably 50 moles, and even more preferably 45 moles. On the other hand, the lower limit of this number of moles is more preferably 8 moles, and even more preferably 10 moles. Also, for example, 8 to 50 moles is preferred. The proportion of ethylene oxide in the alkylene oxide is preferably 50 mol% or more, and even more preferably 80 mol% or more. When adding two or more types of alkylene oxide, the order of their addition is not particularly limited, and the addition form may be block-shaped or random. The addition of alkylene oxide can be carried out by known methods, but it is generally carried out in the presence of a basic catalyst. 【0074】Polyhydroxyesters can be produced, for example, by esterifying a polyhydric alcohol with a hydroxy fatty acid (hydroxy monocarboxylic acid) under normal conditions to obtain an esterified product, and then adding an alkylene oxide to this esterified product. Polyhydroxyesters can also be suitably produced by using naturally obtained oils and fats such as castor oil, or hydrogenated castor oil obtained by adding hydrogen to castor oil, and then adding an alkylene oxide to these products. 【0075】 Nonionic surfactants (B2) also include esters in which at least one hydroxyl group of the above-mentioned polyhydroxy ester is encapsulated with a fatty acid. The number of carbon atoms in the encapsulated fatty acid is preferably 6 to 24, and more preferably 12 to 18. The number of carbon atoms in the hydrocarbon group in the fatty acid may be distributed, the hydrocarbon group may be linear or branched, saturated or unsaturated, and may have a polycyclic structure. Examples of such fatty acids include lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, eicosanoic acid, behenic acid, and lignoceric acid. There are no particular limitations on the esterification method or reaction conditions, and known methods and ordinary conditions can be used. 【0076】 Examples of polyhydroxyesters and esters in which at least one hydroxyl group of a polyhydroxyester is sequestered with a fatty acid include hydrogenated castor oil ethylene oxide adduct, castor oil ethylene oxide adduct, hydrogenated castor oil ethylene oxide adduct monooleate, hydrogenated castor oil ethylene oxide adduct dioleate, hydrogenated castor oil ethylene oxide adduct trioleate, castor oil ethylene oxide adduct trioleate, hydrogenated castor oil ethylene oxide adduct tristearate, and among these, hydrogenated castor oil ethylene oxide adduct, hydrogenated castor oil ethylene oxide adduct trioleate, and hydrogenated castor oil ethylene oxide adduct tristearate are preferred in terms of compatibility with the treatment agent, oil film strength, and reduction of fluff. 【0077】(Polyoxyalkylene polyhydric alcohol ethers) Polyoxyalkylene polyhydric alcohol ethers are compounds having a structure in which an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide is added to a polyhydric alcohol. Examples of polyhydric alcohols include ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, sorbitan, sorbitol, ditrimethylolpropane, dipentaerythritol, and sucrose. Among these, glycerin, trimethylolpropane, and sucrose are preferred. 【0078】 There are no particular limitations on the number of moles of alkylene oxide to be added, but 3 to 100 moles are preferred in terms of emulsification. The upper limit of the number of moles to be added is more preferably 70 moles, and even more preferably 50 moles. On the other hand, the lower limit of the number of moles to be added is more preferably 4 moles, and even more preferably 5 moles. Also, for example, 4 to 70 moles are more preferred, and even more preferably 5 to 50 moles. Furthermore, the proportion of ethylene oxide in the alkylene oxide is preferably 50 mol% or more, and even more preferably 80 mol% or more. There are no particular limitations on the weight-average molecular weight of the polyoxyalkylene polyhydric alcohol ether, but 300 to 10000 are preferred in terms of emulsification and oil film strength. The upper limit of the average molecular weight is more preferably 8000, and even more preferably 500. On the other hand, the average molecular weight is more preferably 400, and even more preferably 500. Also, for example, 400 to 8000 are more preferred, and even more preferably 500 to 5000. 【0079】Examples of polyoxyalkylene polyhydric alcohol ethers include, but are not limited to, polyethylene glycol, glycerin ethylene oxide adduct, trimethylolpropane ethylene oxide adduct, pentaerythritol ethylene oxide adduct, diglycerin ethylene oxide adduct, sorbitan ethylene oxide adduct, sorbitan ethylene oxide propylene oxide adduct, sorbitol ethylene oxide adduct, sorbitol ethylene oxide propylene oxide adduct, ditrimethylolpropane ethylene oxide adduct, dipentaerythritol ethylene oxide adduct, and sucrose ethylene oxide adduct. 【0080】 (Polyoxyalkylene polyhydric alcohol fatty acid esters) Polyoxyalkylene polyhydric alcohol fatty acid esters are compounds having a structure in which a compound in which an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide is added to a polyhydric alcohol is esterified with a fatty acid. Examples of polyhydric alcohols include glycerin, trimethylolpropane, pentaerythritol, erythritol, diglycerin, sorbitan, sorbitol, ditrimethylolpropane, dipentaerythritol, and sucrose. Among these, glycerin, diglycerin, sorbitan, and sorbitol are preferred. 【0081】 Examples of fatty acids include lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, isocetyl acid, stearic acid, isostearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, arachidic acid, eicosenoic acid, behenic acid, isodocosanoic acid, erucic acid, lignoceric acid, and isotetracosanoic acid. 【0082】There are no particular limitations on the number of moles of alkylene oxide to be added, but 3 to 100 moles is preferred in terms of emulsification. The upper limit of the number of moles to be added is more preferably 70 moles, and even more preferably 50 moles. On the other hand, the lower limit of the number of moles to be added is more preferably 5 moles, and even more preferably 7 moles. Also, for example, 5 to 70 moles is more preferred, and even more preferably 10 to 50 moles. Furthermore, the proportion of ethylene oxide in the alkylene oxide is preferably 50 mol% or more, and even more preferably 80 mol% or more. There are no particular limitations on the weight-average molecular weight of the polyoxyalkylene polyhydric alcohol fatty acid ester, but for example, 300 to 7000 is preferred. The upper limit of the average molecular weight is more preferably 5000, and even more preferably 3000. On the other hand, the average molecular weight is more preferably 500, and even more preferably 700. Also, for example, 500 to 5000 is more preferred, and even more preferably 700 to 3000. 【0083】 Examples of polyoxyalkylene polyhydric alcohol fatty acid esters include, but are not limited to, glycerol ethylene oxide adduct monolaurate, glycerol ethylene oxide adduct dilaurate, glycerol ethylene oxide adduct trilaurate, trimethylolpropane ethylene oxide adduct trilaurate, sorbitan ethylene oxide adduct monooleate, sorbitan ethylene oxide adduct dioleate, sorbitan ethylene oxide adduct trioleate, sorbitan ethylene oxide propylene oxide adduct monooleate, sorbitan ethylene oxide propylene oxide adduct dioleate, sorbitan ethylene oxide propylene oxide adduct trioleate, sorbitan ethylene oxide propylene oxide adduct trilaurate, sucrose ethylene oxide adduct trilaurate, etc. 【0084】(Polyoxyalkylene aliphatic alcohol ethers) Polyoxyalkylene aliphatic alcohol ethers are compounds having a structure in which an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide is added to an aliphatic monohydric alcohol. Examples of polyoxyalkylene aliphatic alcohol ethers include alkylene oxide adducts of aliphatic alcohols such as octyl alcohol, 2-ethylhexyl alcohol, decyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, stearyl alcohol, isostearyl alcohol, and oleyl alcohol. There are no particular limitations on the number of moles of alkylene oxide added, but 1 to 100 moles is preferred. The upper limit of the number of moles added is more preferably 70 moles, and even more preferably 50 moles. On the other hand, the lower limit of the number of moles added is more preferably 2 moles, and even more preferably 3 moles. Also, for example, 2 to 70 moles is more preferred, and even more preferably 3 to 50 moles. Furthermore, the ratio of ethylene oxide to the total alkylene oxide is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more. 【0085】 (Fatty acid esters of polyalkylene glycol) Fatty acid esters of polyalkylene glycol are compounds having a structure in which polyoxyethylene glycol, polyoxyethylene polyoxypropylene glycol, and a fatty acid are ester-bonded. The weight-average molecular weight of polyalkylene glycol is not particularly limited, but for example, 100 to 1500 is preferred. The upper limit of the average molecular weight is more preferably 1400, and even more preferably 1200. On the other hand, the average molecular weight is more preferably 150, and even more preferably 200. Also, for example, 150 to 1400 is more preferred, and even more preferably 200 to 1200. 【0086】Examples of polyalkylene glycol fatty acid esters include, but are not limited to, polyethylene glycol monolaurate, polyethylene glycol dilaurate, polyethylene glycol monooleate, polyethylene glycol dioleate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene polypropylene glycol monolaurate, polyethylene polypropylene glycol dilaurate, polyethylene polypropylene glycol monooleate, and polyethylene polypropylene glycol dioleate. 【0087】 (Polyhydric alcohol fatty acid esters) Polyhydric alcohol fatty acid esters are compounds having a structure in which a polyhydric alcohol and a fatty acid are ester-bonded, and are compounds excluding the smooth component (A) mentioned above. Examples of polyhydric alcohols include ethylene glycol, trimethylolpropane, pentaerythritol, erythritol, diethylene glycol, diglycerin, sorbitan, sorbitol, ditrimethylolpropane, and sucrose. Among these, ethylene glycol, glycerin, diglycerin, sorbitan, and sorbitol are preferred. 【0088】 Examples of fatty acids include lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, isocetyl stearic acid, isostearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, tuberculinostearic acid, isoeicosanoic acid, gadoleic acid, eicosenoic acid, behenic acid, isodocosanoic acid, erucic acid, and lignoceric acid. 【0089】 Furthermore, the polyhydric alcohol fatty acid ester has at least one or more hydroxyl groups. The weight-average molecular weight of the polyhydric alcohol fatty acid ester is not particularly limited, but is preferably 100 to 1000. The upper limit of the average molecular weight is more preferably 800, and even more preferably 600. On the other hand, the average molecular weight is more preferably 200, and even more preferably 300. Also, for example, is more preferably 200 to 800, and even more preferably 300 to 600. 【0090】Examples of fatty acid esters include, but are not limited to, glycerol monolaurate, glycerol dilaurate, glycerol monooleate, glycerol dioleate, sorbitan monooleate, sorbitan dioleate, sucrose monolaurate, and sucrose dilaurate. 【0091】 There are no particular limitations on the nonionic surfactant (B2), but from the viewpoint of improving heat resistance, it is preferable to use one that has been purified by removing catalysts, etc. 【0092】 [Cationic surfactants] Cationic surfactants are not particularly limited, but examples include alkylamine salts, alkylimidazolinium salts, and quaternary ammonium salts. 【0093】 [Amphoteric surfactants] There are no particular limitations on amphoteric surfactants, but examples include lauryldimethylbetaine, stearyldimethylbetaine, and dimethyllaurylamine oxide. 【0094】 [Treatment Agent for Synthetic Fibers] The treatment agent for synthetic fibers of the present invention contains a smoothing component (A) and a surfactant (B), and the iodine value, strong acid value, and kinematic viscosity of the nonvolatile components of the treatment agent are within a specific range, resulting in excellent low-temperature stability. The reason for the excellent low-temperature stability is not particularly limited, but it is thought to be because the components constituting the treatment agent become more miscible with each other, thereby maintaining a stable appearance over a wide temperature range. 【0095】 The weight percentage of the smoothing component (A) in the non-volatile content of the treatment agent is not particularly limited, but 20 to 70% by weight is preferred in terms of smoothness. The upper limit of the weight percentage is preferred in the following order: (1) 70% by weight, (2) 65% by weight, (3) 60% by weight, (4) 55% by weight, and (5) 50% by weight (the larger the number in parentheses, the more preferred). On the other hand, the lower limit of the weight percentage is preferred in the following order: (1) 30% by weight, (2) 35% by weight, (3) 40% by weight, and (4) 45% by weight (the larger the number in parentheses, the more preferred). Furthermore, for example, 30 to 65% by weight is more preferred, 35 to 65% by weight is even more preferred, and 40 to 60% by weight is particularly preferred. 【0096】The weight percentage of surfactant (B) in the non-volatile content of the treatment agent is not particularly limited, but 5 to 75% by weight is preferred in terms of emulsification. The upper limit of the weight percentage is preferred in the following order: (1) 75% by weight, (2) 70% by weight, (3) 60% by weight, (4) 50% by weight, and (5) 40% by weight (the larger the number in parentheses, the more preferred). On the other hand, the lower limit of the weight percentage is preferred in the following order: (1) 5% by weight, (2) 6% by weight, (3) 7% by weight, (4) 8% by weight, (5) 20% by weight, and (6) 30% by weight (the larger the number in parentheses, the more preferred). Furthermore, for example, 6 to 65% by weight is more preferred, and 7 to 60% by weight is even more preferred. 【0097】 The weight percentage of the anionic surfactant (B1) in the nonvolatile content of the treatment agent is not particularly limited, but is preferably 0.01 to 15% by weight in terms of antistatic properties and emulsifying properties. The upper limit of the weight percentage is preferably (1) 15% by weight, (2) 12% by weight, (3) 11% by weight, (4) 10% by weight, (5) 7% by weight, and (6) 5% by weight, in that order (the larger the number in parentheses, the more preferable). On the other hand, the lower limit of the weight percentage is preferably (1) 0.01% by weight, (2) 0.02% by weight, (3) 0.05% by weight, (4) 0.1% by weight, (5) 1% by weight, and (6) 2% by weight, in that order (the larger the number in parentheses, the more preferable). The upper limit of the weight percentage is more preferably 12% by weight, even more preferably 11% by weight, and particularly preferably 10% by weight. On the other hand, the lower limit of the weight percentage is more preferably 0.02% by weight, even more preferably 0.05% by weight, and particularly preferably 0.1% by weight. Also, for example, 0.02 to 12% by weight is more preferably, and 0.05 to 11% by weight is even more preferably. 【0098】The weight percentage of the sulfur-containing anionic surfactant (B1-1) in the nonvolatile content of the treatment agent is not particularly limited, but is preferably 0.01 to 10% by weight in terms of compatibility and heat resistance. The upper limit of the weight percentage is preferably (1) 10% by weight, (2) 7% by weight, (3) 6% by weight, (4) 5% by weight, and (5) 4% by weight (the larger the number in parentheses, the more preferable). On the other hand, the lower limit of the weight percentage is preferably (1) 0.01% by weight, (2) 0.02% by weight, (3) 0.05% by weight, (4) 0.1% by weight, (5) 1% by weight, and (6) 2% by weight (the larger the number in parentheses, the more preferable). Furthermore, for example, 0.02 to 7% by weight is more preferable, and 0.05 to 6% by weight is even more preferable. 【0099】 The weight percentage of the organic sulfonic acid compound represented by general formula (2) in the nonvolatile content of the treatment agent is not particularly limited, but is preferably 0.01 to 10% by weight in terms of compatibility and heat resistance. The upper limit of the weight percentage is preferably (1) 10% by weight, (2) 7% by weight, (3) 6% by weight, (4) 5% by weight, and (5) 4% by weight (the larger the number in parentheses, the more preferable). On the other hand, the lower limit of the weight percentage is preferably (1) 0.01% by weight, (2) 0.02% by weight, (3) 0.05% by weight, (4) 0.1% by weight, (5) 1% by weight, and (6) 2% by weight (the larger the number in parentheses, the more preferable). Furthermore, for example, 0.02 to 7% by weight is more preferable, and 0.05 to 7% by weight is even more preferable. 【0100】 The weight percentage of the organic sulfonic acid compound represented by general formula (3) in the non-volatile content of the treatment agent is not particularly limited, but is preferably 0.0001 to 5% by weight in terms of compatibility and heat resistance. The upper limit of this weight percentage is more preferably 3.5% by weight, even more preferably 3% by weight, and particularly preferably 2.5% by weight. On the other hand, the lower limit of this weight percentage is more preferably 0.0002% by weight, even more preferably 0.0003% by weight, and particularly preferably 0.0004% by weight. Also, for example, is more preferably 0.0002 to 3.5% by weight, and even more preferably 0.0003 to 3% by weight. 【0101】The weight percentage of the organophosphate ester compound (B1-2) in the nonvolatile content of the treatment agent is not particularly limited, but 0 to 10% by weight is preferred in terms of compatibility and heat resistance. The upper limit of this weight percentage is more preferably 7% by weight, even more preferably 6% by weight, and particularly preferably 5% by weight. On the other hand, the lower limit of this weight percentage is more preferably 0% by weight, even more preferably 0.001% by weight, and particularly preferably 0.1% by weight. Also, for example, 0 to 7% by weight is more preferred, and even more preferably 0.001 to 6% by weight. 【0102】 The weight percentage of the compound represented by general formula (4) in the non-volatile content of the treatment agent is not particularly limited, but 0 to 10% by weight is preferred in terms of compatibility and heat resistance. The upper limit of this weight percentage is more preferably 7% by weight, even more preferably 6% by weight, and particularly preferably 5% by weight. On the other hand, the lower limit of this weight percentage is more preferably 0.001% by weight, even more preferably 0.01% by weight, and particularly preferably 0.1% by weight. Also, for example, 0.001 to 7% by weight is more preferred, and 0.01 to 6% by weight is even more preferred. 【0103】 The weight percentage of the compound represented by general formula (5) in the nonvolatile content of the treatment agent is not particularly limited, but 0 to 10% by weight is preferred in terms of compatibility and heat resistance. The upper limit of this weight percentage is more preferably 7% by weight, even more preferably 6% by weight, and particularly preferably 5% by weight. On the other hand, the lower limit of this weight percentage is more preferably 0.0001% by weight, even more preferably 0.001% by weight, and particularly preferably 0.01% by weight. Also, for example, 0.0001 to 7% by weight is more preferred, and 0.001 to 6% by weight is even more preferred. 【0104】The weight percentage of the nonionic surfactant (B2) in the nonvolatile content of the treatment agent is not particularly limited, but 5 to 70% by weight is preferred in terms of emulsifying properties and oil film strength. The upper limit of the weight percentage is preferred in the following order: (1) 70% by weight, (2) 60% by weight, (3) 50% by weight, (4) 40% by weight, and (5) 30% by weight (the larger the number in parentheses, the more preferred). On the other hand, the lower limit of the weight percentage is preferred in the following order: (1) 5% by weight, (2) 6% by weight, (3) 7% by weight, (4) 8% by weight, (5) 15% by weight, and (6) 25% by weight (the larger the number in parentheses, the more preferred). Furthermore, for example, 6 to 60% by weight is more preferred, and 7 to 50% by weight is even more preferred. 【0105】 The iodine value of the non-volatile portion of the treatment agent of the present invention is 5 to 100. By keeping the iodine value within a predetermined range, both low-temperature stability and heat resistance can be achieved. The upper limit of the iodine value is preferably in the order of (1) 100, (2) 90, (3) 85, (4) 80, and (5) 70 (higher numbers in parentheses are more preferable). On the other hand, the lower limit of the iodine value is preferably in the order of (1) 5, (2) 6, (3) 8, (4) 10, and (5) 20 (higher numbers in parentheses are more preferable). For example, 6 to 90 is preferred, and 8 to 85 is more preferred. In this invention, the non-volatile content of the treatment agent refers to the components on an aluminum sheet when 2.0 to 3.0 g of the treatment agent is spread flat on the aluminum sheet, dried at 110°C under infrared lamp irradiation, and the fluctuation range of the volatile content over 150 seconds becomes 0.15%, or the oven-dried components when the treatment agent is extracted from synthetic fibers using an extraction solvent in which the treatment agent dissolves (water, methanol, ethanol, isopropanol, methyl ethyl ketone, hexane, cyclohexane, etc.), heat-treated at 110°C to remove the extraction solvent, and a constant weight is reached. Furthermore, in this invention, the iodine value is a value measured according to JIS K-0070. The iodine value can be adjusted by adjusting the content of raw materials that contain many double and triple bonds. 【0106】The strong acid value of the non-volatile content of the treatment agent of the present invention is 0.0 to 0.3 mg KOH / g. By setting the strong acid value within a predetermined range, both low-temperature stability and heat resistance can be achieved. The upper limit of the strong acid value is preferably 0.2 mg KOH / g, more preferably 0.15 mg KOH / g, and even more preferably 0.1 mg KOH / g. On the other hand, the lower limit of the strong acid value is preferably 0 mg KOH / g. The strong acid value in the present invention is determined by the method described in the examples. The strong acid value shows a high value due to the presence of strongly acidic components (such as p-toluenesulfonic acid used as a catalyst in the esterification reaction). By removing the strongly acidic components through purification treatments such as washing with water or filtration using an adsorbent, the value can be lowered. In addition, the strong acid value can be lowered by not using strongly acidic components, such as performing the esterification reaction without a catalyst. 【0107】 The treatment agent of the present invention has a kinematic viscosity of the non-volatile content exceeding 60 mm ２ / s and being 1000 mm ２ / s or less at 25°C. By setting the kinematic viscosity within a predetermined range, both low-temperature stability and reduction of smoke generation and fluff can be achieved. The upper limit of the kinematic viscosity is preferably 900 mm ２ / s or less, more preferably 800 mm ２ / s or less, and even more preferably 700 mm ２ / s or less. On the other hand, the lower limit of the kinematic viscosity is more preferably 65 mm ２ / s or more, and even more preferably 70 mm ２ / s or more. Also, for example, 62 mm ２ / s or more and 900 mm ２ / s or less is preferable, and 65 mm ２ / s or more and 700 mm ２ / s or less is more preferable. 【0108】 The treatment agent of the present invention contains sulfate ions (SO ４ ２－The content of ) is not particularly limited, but is preferably 1000 ppm or less in terms of low-temperature stability and heat resistance. The upper limit of the content is more preferably in the order of (1) 600 ppm, (2) 500 ppm, (3) 350 ppm, (4) 200 ppm, and (5) 100 ppm (the larger the number in parentheses, the more preferable). On the other hand, the lower limit of the content is more preferably in the order of (1) 0 ppm, (2) 0.1 ppm, (3) 2 ppm, (4) 5 ppm, and (5) 20 ppm (the larger the number in parentheses, the more preferable). Also, for example, 0.1 ppm to 600 ppm is preferred, 2 ppm to 500 ppm is more preferred, and 5 ppm to 350 ppm is even more preferred. 【0109】 The treatment agent of the present invention contains chloride ions (Cl) detected from the nonvolatile components of the treatment agent by ion chromatography. － The content is not particularly limited, but it is preferable to be 1000 ppm or less in terms of low-temperature stability and heat resistance. The upper limit of the content is more preferable in the order of (1) 600 ppm, (2) 500 ppm, (3) 350 ppm, (4) 200 ppm, and (5) 100 ppm (the larger the number in parentheses, the more preferable). On the other hand, the lower limit of the content is more preferable in the order of (1) 0 ppm, (2) 0.001 ppm, (3) 0.1 ppm, (4) 1 ppm, and (5) 3 ppm (the larger the number in parentheses, the more preferable). Also, for example, 0.001 ppm to 600 ppm is preferable, 0.1 ppm to 500 ppm is more preferable, and 1 ppm to 350 ppm is even more preferable. The method for analyzing sulfate ions and chloride ions by ion chromatography in this invention is as described in the examples. 【0110】 As mentioned above, the weight ratio of sulfate ions and chloride ions can be adjusted by reducing the amount of sodium sulfate and sodium chloride contained in the raw materials containing organic sulfonic acid compounds. 【0111】 The treatment agent of the present invention is detected from the non-volatile components of the treatment agent by ion chromatography, and phosphate ions (PO) ４ ３－The content of phosphate ions (PO) is preferably 1000 ppm or less. When the content of phosphate ions is 1000 ppm or less, thread breakage and shattering tend to be reduced. The content is more preferably in the order of (1) 400 ppm, (2) 200 ppm, (3) 100 ppm, (4) 75 ppm, and (5) 50 ppm (the larger the number in parentheses, the more preferable). On the other hand, the lower limit of the content is preferably in the order of (1) 0 ppm, (2) 0.1 ppm, (3) 3 ppm, (4) 5 ppm, and (5) 15 ppm (the larger the number in parentheses, the more preferable). Also, for example, 0.1 ppm to 400 ppm is preferred, 3 ppm to 200 ppm is more preferred, and 5 ppm to 100 ppm is even more preferred. ４ ３－ This is sometimes simply called a phosphate ion. The method for analyzing phosphate ions by ion chromatography in this invention is as described in the examples. 【0112】 As mentioned above, the phosphate ion content can be adjusted by reducing the amount of inorganic phosphoric acid and / or its salt contained in the organic phosphate ester compound (B1-2), adjusting the amount of organic phosphate ester compound (B1-2) used, or by filtering the treatment agent using a filter aid such as diatomaceous earth. 【0113】 The P element content of the treatment agent of the present invention, as detected from the non-volatile components of the treatment agent by ICP emission spectrometry, is not particularly limited, but is preferably 5000 ppm or less in terms of heat resistance. The upper limit of the content is more preferably 4000 ppm, and even more preferably 500 ppm. On the other hand, the lower limit of the content is preferably 0 ppm, even more preferably 0.1 ppm, and even more preferably 5 ppm. Also, for example, 0.1 to 4000 ppm is more preferable, and 5 to 500 ppm is even more preferable. 【0114】The synthetic fiber treatment agent of the present invention may further contain an antioxidant to impart heat resistance. Known antioxidants include phenolic, thio, and phosphite-based antioxidants. One or more antioxidants may be used. When an antioxidant is included, the weight percentage of the antioxidant in the nonvolatile content of the treatment agent is not particularly limited, but is preferably 0.1 to 5% by weight. The upper limit of this weight percentage is more preferably 4.5% by weight, and even more preferably 4% by weight. On the other hand, the lower limit of this weight percentage is more preferably 0.2% by weight, and even more preferably 0.3% by weight. Also, for example, 0.1 to 3% by weight is more preferably, and even more preferably 0.3 to 4% by weight. 【0115】 Furthermore, the synthetic fiber treatment agent of the present invention may further contain a stock stabilizer (for example, water, ethylene glycol, or propylene glycol). The weight percentage of the stock stabilizer in the treatment agent is preferably 0.1 to 30% by weight. The upper limit of this weight percentage is more preferably 20% by weight, and even more preferably 15% by weight. On the other hand, the lower limit of this weight percentage is more preferably 0.2% by weight, and even more preferably 0.5% by weight. Also, for example, 0.2 to 20% by weight is more preferably, and even more preferably 0.5 to 15% by weight. 【0116】 The synthetic fiber treatment agent of the present invention may consist solely of the aforementioned components comprising nonvolatile components, or it may consist of nonvolatile components and a stock solution stabilizer, or it may be a nonvolatile component diluted with a low-viscosity mineral oil, or it may be an aqueous emulsion in which the nonvolatile components are emulsified in water. When the synthetic fiber treatment agent of the present invention is an aqueous emulsion in which the nonvolatile components are emulsified in water, the concentration of the nonvolatile components is preferably 5 to 35% by weight. The upper limit of the concentration is more preferably 30% by weight, and even more preferably 28% by weight. On the other hand, the lower limit of the concentration is more preferably 6% by weight, and even more preferably 8% by weight. Also, for example, 6 to 30% by weight is more preferably, and even more preferably 8 to 28% by weight. 【0117】The method for producing the synthetic fiber treatment agent of the present invention is not particularly limited, and known methods can be employed. The synthetic fiber treatment agent is produced by adding and mixing the constituent components in any or specific order. From the viewpoint of improving heat resistance, purified versions of each component, such as catalysts, may be used. In particular, the smoothing component (A) and surfactant (B) used in the present invention may contain inorganic substances, and it is desirable to remove and purify the inorganic substances in order to improve the stability and heat resistance of the treatment agent. Known methods can be used to remove and purify inorganic substances, but for example, the smoothing component (A) can be removed by filtration using diatomaceous earth, and the nonionic surfactant can be purified by adsorption removal using an inorganic synthetic adsorbent. Bio-based raw materials may be used for each component constituting the synthetic fiber treatment agent of the present invention. In addition to the above components, the synthetic fiber treatment agent of the present invention may contain known components used in synthetic fiber treatment agents, and may have known physical properties in synthetic fiber treatment agents. 【0118】 [Synthetic Fiber, Method for Manufacturing Synthetic Fiber, and Fiber Structure] The synthetic fiber of the present invention is obtained by applying the synthetic fiber treatment agent of the present invention. The synthetic fiber of the present invention has excellent yarn quality because it is treated with the synthetic fiber of the present invention. There are no particular limitations on the method for manufacturing the synthetic fiber, but it can be suitably manufactured by the method for manufacturing the synthetic fiber of the present invention. The method for manufacturing the synthetic fiber of the present invention includes a step of applying the synthetic fiber treatment agent of the present invention to the raw synthetic fiber. According to the manufacturing method of the invention, the occurrence of scum and yarn breakage can be reduced, and synthetic fibers with excellent yarn quality can be obtained. In this invention, the raw synthetic fiber refers to synthetic fiber to which the treatment agent has not been applied. 【0119】There are no particular limitations on the process of applying the synthetic fiber treatment agent, and known methods can be employed. Typically, the synthetic fiber treatment agent is applied during the spinning process of the raw synthetic fiber. After the treatment agent is applied, the fiber is stretched and heat-set using a hot roller and then wound up. Thus, the synthetic fiber treatment agent of the present invention can be suitably used when there is a step of heat stretching after the treatment agent is applied without being wound up. As an example of the temperature during heat stretching, for polyester and nylon, 210 to 260°C is assumed for industrial materials, and 110 to 220°C is assumed for clothing. 【0120】 As mentioned above, synthetic fiber treatment agents applied to raw synthetic fibers include treatment agents consisting solely of non-volatile components, treatment agents in which non-volatile components are diluted with low-viscosity mineral oil, and water-based emulsion treatment agents in which non-volatile components are emulsified in water. While there are no particular limitations on the application method, examples include guide lubrication, roller lubrication, dip lubrication, and spray lubrication. Among these, guide lubrication and roller lubrication are preferred due to their ease of control over the application amount. 【0121】 There are no particular limitations on the amount of non-volatile components added to the synthetic fiber treatment agent, but in terms of reducing fluff and providing antistatic properties, 0.05 to 5% by weight is preferred, 0.1 to 3% by weight is more preferred, and 0.1 to 2% by weight is even more preferred, relative to the raw synthetic fiber. 【0122】(Raw materials) Examples of synthetic fibers include polyester fibers, polyamide fibers, and polyolefin fibers. The synthetic fiber treatment agent of the present invention is suitable for synthetic fibers such as polyester fibers, polyamide fibers, and polyolefin fibers. Examples of polyester fibers include polyester (PET) mainly composed of ethylene terephthalate, polyester (PTT) mainly composed of trimethylene ethylene terephthalate, polyester (PBT) mainly composed of butylene ethylene terephthalate, and polyester (PLA) mainly composed of lactic acid. Examples of polyamide fibers include nylon 6 and nylon 66. Examples of polyolefin fibers include polypropylene and polyethylene. There are no particular limitations on the method of manufacturing synthetic fibers, and known methods can be used. (Raw materials) There are no particular limitations on the form of synthetic fibers, but multifilaments or monofilaments are preferred. 【0123】 (Fiber Structures) The fiber structures of the present invention include synthetic fibers obtained by the manufacturing method of the present invention described above. Specifically, these include fabrics woven on a water jet loom, air jet loom, or rapier loom using synthetic fibers treated with the synthetic fiber treatment agent of the present invention, knitted fabrics knitted on a circular knitting machine, warp knitting machine, or weft knitting machine, and cords and ropes obtained by twisting yarn. Applications of the fiber structures include industrial materials such as tire cords, seat belts, airbags, fishing nets, and ropes, as well as clothing. There are no particular limitations on the method of manufacturing the fabrics and knitted fabrics, and known methods can be used. 【0124】 The present invention will be described below with reference to examples. The present invention is not limited to the examples described herein. In the text and tables, "%" means "weight percent". 【0125】[Examples 1-39, Comparative Examples 1-15] The smoothing agent (A), surfactant (B), additive (C), and volatile diluent (D) listed in Tables 1-6 were mixed and stirred until homogeneous to prepare the synthetic fiber treatment agents for Examples 1-39 and Comparative Examples 1-15. Using each prepared treatment agent, the low-temperature stability, pin dirt accumulation, pin dirt wipeability, tension fluctuation, and smoke generation were evaluated by the following methods. In addition, the iodine value, strong acid value, and sulfate ion (SO4) were evaluated using the non-volatile components of the treatment agent by the following methods. ４ ２－ )・Chloride ions (Cl － )・P element content・Phosphate ion (PO ４ ３－ The following measurements were taken. The results are shown in Tables 1 to 6. 【0126】 (Evaluation of low-temperature stability) The treatment agent prepared above was placed in a glass bottle, sealed, and left to stand at -5°C for 7 days to perform low-temperature treatment. After that, it was placed in an environmental testing chamber heated to 25°C and left to stand for 24 hours and then for 48 hours. The appearance was observed visually and judged according to the evaluation criteria below to evaluate the low-temperature stability. 【0127】 Low-temperature stability was evaluated according to the following criteria: ◎: After standing for 24 hours, it returns to its original state or remains unchanged from the state before low-temperature treatment, indicating excellent low-temperature stability. ○: Precipitates are observed after standing for 24 hours, but it returns to the state before low-temperature treatment after standing for 48 hours, indicating excellent low-temperature stability. ×: Precipitates are observed after both 24 hours and 48 hours of standing, indicating poor low-temperature stability. 【0128】 (Evaluation of pin dirt accumulation, pin dirt wipeability, and tension fluctuations) The treatment agent, which was evaluated for low temperature stability as described above, was quantitatively applied at a concentration of 20% by weight to 1000 denier, 96 filament untreated polyester filaments. After removing volatile components by passing the filaments through a roller heated to 150°C using a thread-running friction measuring machine, the filaments were brought into contact with a matte chrome pin heated to 250°C. The filaments were run for 4 hours at an initial tension of 500g and a thread-running speed of 2m / min to evaluate the degree of pin dirt accumulation, pin dirt wipeability, and tension fluctuations. In addition, 20% by weight of the treatment agent was applied to simulate evaluation under more severe conditions. 【0129】The degree of dirt accumulation on the pins was evaluated according to the following criteria: ◎: Almost no dirt was observed, indicating excellent pin dirt accumulation. ○: Only slight dirt was observed, indicating excellent pin dirt accumulation. ×: Dirt was clearly accumulated, indicating poor pin dirt accumulation. 【0130】 The tension fluctuation value was calculated using the following formula: Tension fluctuation value (g) = Tension after running the thread for 4 hours (g) - Initial tension (g) Furthermore, the tension fluctuation value was evaluated according to the following criteria: ◎: 0g to less than 30g, excellent heat resistance. ○: 30g or more and less than 50g, excellent heat resistance. ×: 50g or more, poor heat resistance. 【0131】 The ability to wipe away dirt from the pins was evaluated using the following method. Dirt that had accumulated on the pear-colored chromium pins was wiped off with gauze soaked in a solution of sodium hydroxide dissolved in water and glycerin. The number of wipes required to remove the dirt was used to evaluate the ability to wipe away dirt. ◎: Dirt could be wiped off in fewer than 5 wipes, indicating excellent dirt-removal ability of the pins. ○: Dirt could be wiped off in 5 to 20 wipes, indicating excellent dirt-removal ability of the pins. ×: Dirt could not be wiped off in 20 or more wipes, indicating poor dirt-removal ability of the pins. 【0132】 (Evaluation of smoke generation) The treatment agent prepared above was quantitatively applied to 1000 denier, 96-filament oil-free polyester filaments at a concentration of 1% by weight in terms of non-volatile content, and the samples were left to stand for 24 hours. After removing volatile components by passing the samples through a roller heated to 150°C using a thread-running friction measuring machine, the amount of smoke generated when the samples were brought into contact with a matte chrome pin heated to 250°C was measured for 1 minute. A digital dust meter P-5H2 (Shibata Scientific Co., Ltd.) was used to measure the amount of smoke generated, and the thread-running speed was 50 m / min. The amount of smoke generated was evaluated from the values ​​of smoke generation according to the following criteria: ◎: Less than 1000 CPM, very low smoke generation, excellent. 〇: 1000 CPM or more, less than 3000 CPM, low smoke generation, excellent. △: 3000 CPM or more, less than 5000 CPM, high smoke generation, slightly inferior. ×: Exceeding 5000 CPM, it has very high smoke generation and is inferior. (CPM: Count per Minute) 【0133】 (Method for measuring strong acid value) The strong acid value was measured according to the method specified in JIS K 2501 (2003). Specifically, the non-volatile components of the treatment agent were used as the sample for measurement, dissolved in the mixed solvent described below, and titrated with thymol blue as an indicator. The titration was carried out with a 0.1 mol / L potassium hydroxide standard solution until it turned yellow, and the strong acid value was calculated by applying the titration volume of potassium hydroxide standard solution to the following formula. As the mixed solvent for dissolving the sample, a mixture of denatured alcohol and xylol was used, to which thymol blue was added, and then it was made red with a 0.1 mol / L hydrochloric acid standard solution, and then yellow with a 0.1 mol / L potassium hydroxide standard solution. Strong acid value = (5.61 × A × f) / S (Formula) (In the above formula, A is the titration volume of 0.1 mol / L potassium hydroxide solution (mL), f is the titer of 0.1 mol / L potassium hydroxide solution, and S is the weight of the sample (g)) If the color of the solution does not change from before dissolution when the non-volatile components of the treatment agent are dissolved in the mixed solvent, the strong acid value is set to 0 mg KOH / g. 【0134】 (Method for measuring the amount of element P detected from the non-volatile components of a treatment agent by ICP emission spectrometry) (1) Pretreatment 0.5 g of the non-volatile components of a synthetic fiber treatment agent (or an amount such that the amount of element P contained in the non-volatile components of the synthetic fiber treatment agent is 1 to 100 ppm) was weighed into a platinum crucible, 5 ml of alkaline solution (a homogeneous mixture of 35 g of potassium hydroxide, 915 ml of ethanol, and 50 g of ultrapure water) was added thereto, and the mixture was gradually heated in an electric furnace to ash it at 800 to 850°C. After cooling to room temperature, ultrapure water was added to make a total volume of 50 ml, which was used as the measurement sample. (2) Calibration curve Standard solutions of 100 ppm, 10 ppm, and 1 ppm with known concentrations of element P were prepared in advance. These were subjected to ICP (measurement instrument name: Shimadzu Corporation ICPS-8100, ICP emission spectrometer), and a calibration curve was created using the standard solutions. (3) Measurement The above measurement samples were subjected to ICP (measurement instrument name: Shimadzu Corporation ICPS-8100, ICP emission spectrometer), and the P element content of the nonvolatile synthetic fiber treatment agent was measured using the calibration curve prepared in (2) above. 【0135】 (Sulfate ions (SO ４ ２－ )・Chloride ions (Cl － )・Phosphate ion (PO４ ３－ (Measurement method) 5 g of the sample (non-volatile components of the treatment agent) was accurately weighed, and 95 g of ultrapure water was gradually added while stirring to prepare an aqueous solution, which was then brought to a final volume in a 100 ml volumetric flask. 2 ml of the prepared aqueous solution was passed through an ODS (silica gel with octadecyl groups chemically bonded) pretreatment cartridge to remove lipophilic substances. The solution was subjected to ion chromatography analysis, and detection was performed under the following ion chromatography conditions. The amount detected was measured by the peak area ratio relative to a standard solution of known concentration, and sulfate ions (SO4) were detected. ４ ２－ ), phosphate ion (PO ４ ３－ ), chloride ions (Cl － The amount of ) was converted. <Ion chromatograph conditions> Instrument: Dionex ICS-1500 Suppressor used Analytical column: Dionex IonPac AS14 Inner diameter 4.0 mm x Length 50 mm Guard column: Dionex IonPac AG14 Inner diameter 4.0 mm x Length 250 mm Eluent: 3.5 mmol Na ２ CO ３ , 1.0 mmol NaHCO ３ Flow rate: 1.5ml / min 【0136】 (Measurement of P-nuclear integral ratio) The P-nuclear integral ratios of (B1-2a), (B1-2b), (B1-2c), (B1-2d) in organic phosphate ester compounds (B1-2), and inorganic phosphate are: ３１ The following method was used to calculate the non-volatile content of the sample: Approximately 30 mg of the non-volatile content of the sample was weighed into a 5 mm diameter NMR sample tube, and approximately 0.5 ml of heavy water (D) was added as the deuterating solvent. ２ Add O) and dissolve, ３１ The measurements were taken using a P-NMR measuring device (BRUKER AVANCE400, 162MHz). 【0137】The numbers for the non-volatile content composition of the synthetic fiber treatment agents in Tables 1 to 6 indicate the weight percentage of each component in the non-volatile content of the treatment agent. Details of the treatment agent components used in Tables 1 to 6 are shown below. <Smoothing Components (A)> A-1: ​​Trimethylolpropane tripalm kernel fatty acid (C12-18 linear fatty acid) ester (unrefined) A-2: Trimethylolpropane tripalm kernel fatty acid (C12-18 linear fatty acid) ester A-3: Coconut oil A-4: Palm oil A-5: Palm olein oil A-6: Rapeseed oil A-7: Soybean oil A-8: Sunflower oil A-9: Linseed oil A-10: 2-Ethylhexyl alcohol stearate ester A-11: Oleyl alcohol oleate ester A-12: Dioleyl thiodipropionate (unrefined) A-13: Dioleyl thiodipropionate A-14: Diisocetyl thiodipropionate A-1, A-2, A-3, A-4, A-5, A-6, A-7, A-8 and A-9 are ester compounds (A2), A-10 and A-11 are ester compounds (A1), and A-12, A-13 and A-14 are sulfur-containing ester compounds (A5). 【0138】<Surfactant (B)> <Anionic surfactant (B1)> <Anionic surfactant containing sulfur element (B1-1)> B1-1-1: A compound (mixture) in general formula (2) where the a+b value is 10 to 14 and M is Na. Inorganic impurity reduction treatment is performed. Method of inorganic impurity reduction treatment: B1-1-1 (200 parts) before purification was gradually added to a methanol / ion-exchanged water = 2 / 1 mixture (200 parts) under stirring and completely dissolved at 55±5℃. Next, this solution was allowed to stand for 20 hours to settle the sodium hydroxide, and then the supernatant portion of the liquid was taken out and subjected to vacuum distillation at 50-60℃ to remove methanol and some of the water to obtain B1-1-1. B1-1-2: A compound (mixture) in general formula (2) where the a+b value is 9 to 13 and M is Na. Inorganic impurity reduction treatment is performed. Method for reducing inorganic impurities: 140 parts of unpurified B1-1-2 were gradually added to 260 parts of ion-exchanged water at 80±5°C under stirring, and after complete dissolution, the mixture was cooled to 40±5°C. Next, sodium chloride was removed from this solution using an ion-exchange resin to obtain B1-1-2. B1-1-3: A compound (mixture) in general formula (3) where the values ​​of c+d+e are 8 to 12 and M is Na. Inorganic impurity reduction treatment is performed. Method for reducing inorganic impurities: 200 parts of unpurified B1-1-3 were gradually added to a 3 / 1 mixture of isopropyl alcohol / ion-exchanged water at 55±5°C under stirring, and completely dissolved. Next, this solution was allowed to stand for 20 hours to allow the sodium chloride to settle, and then the supernatant was taken out and subjected to vacuum distillation at 50-60°C to remove isopropyl alcohol and some water to obtain B1-1-3. B1-1-4: A compound (mixture) in general formula (3) where the values ​​of c+d+e are 7 to 11 and M is Na. Inorganic impurity reduction treatment is performed. Method of inorganic impurity reduction treatment: 160 parts of B1-1-4 before purification were gradually added to 240 parts of ion-exchanged water at 75±5°C under stirring, and after complete dissolution, the mixture was cooled to 35±5°C. Next, sodium chloride was removed from this solution using an ion-exchange membrane to obtain B1-1-4. B1-1-5: A compound (mixture) in general formula (2) where the values ​​of a+b are 10 to 14 and M is Na. Inorganic impurity reduction treatment is not performed. B1-1-6: A compound (mixture) in general formula (3) where the values ​​of c+d+e are 8 to 12 and M is Na.No treatment to reduce inorganic impurities. B1-1-7: Dioctyl sulfosuccinate sodium salt. 【0139】 <Organophosphate ester compounds (B1-2)> B1-2-1: Alkyl phosphate having an alkyl group with 11 to 15 carbon atoms (The integral P ratios were: (B1-2a) = 56.72%, (B1-2b) = 40.49%, (B1-2c) = 0.00%, (B1-2d) = 0.00%, inorganic phosphoric acid = 2.79%.) B1-2-2: Isocetyl phosphate (The integral P ratios were: (B1-2a) = 33.05%, (B1-2b) = 29.81%, (B1-2c) = 33.82%, (B1-2d) = 2.76%, inorganic phosphoric acid = 0.56%.) B1-2-3: Oleyl phosphate (The integral ratios of P-nucleus were as follows: (B1-2a) = 55.18%, (B1-2b) = 35.38%, (B1-2c) = 2.43%, (B1-2d) = 0.00%, and inorganic phosphoric acid = 7.01%.) 【0140】 <Fatty Acid Soaps> B1-3: Potassium Oleate Salt <Nonionic Surfactants (B2)> B2-1: Hydrogenated Castor Oil Ethylene Oxide 20-mol Adduct B2-2: Hydrogenated Castor Oil Ethylene Oxide 25-mol Adduct Tristearate (Unpurified) B2-3: Hydrogenated Castor Oil Ethylene Oxide 25-mol Adduct Tristearate B2-4: Hydrogenated Castor Oil Ethylene Oxide 20-mol Adduct Trioleate B2-5: Polyethylene Glycol (Molecular Weight 600) Dioleate B2-6: Polyethylene Glycol (Molecular Weight 200) Dioleate B2-7: Lauryl Alcohol Ethylene Oxide 7-mol Adduct B2-8: Stearic Acid Ester of Condensed Hydrogenated Castor Oil Ether and Maleic Acid B2-9: Random Adduct of 14 Mol Ethylene Oxide and 14 Mol Propylene Oxide of C14-C15 Alcohols <Other Surfactants (B3)> B3-1: Coconut alkylamino ether with 10 molars of ethylene oxide B3-2: Laurylamino ether with 3 molars of ethylene oxide 【0141】<Additives (C)> C-1: Dimethyl silicone 10cst C-2: Antioxidant (Cyanox® 1790, manufactured by Solvay) C-3: Antioxidant (SONGNOX 2450, manufactured by SONGWON) <Volatile Diluents (D)> D-1: Water D-2: Low viscosity mineral oil (Cactus Normal Paraffin YHNP, manufactured by ENEOS) 【0142】 <Production Example 1 (Production of A-1)> In a reaction vessel, 200 g (1.5 mol) of trimethylolpropane, 990 g (4.4 mol) of palm kernel fatty acid, 2.5 g of p-toluenesulfonic acid as an esterification catalyst, and 0.7 g of a 50% aqueous solution of hypophosphorous acid as a color inhibitor were charged. Under a nitrogen atmosphere, the temperature was gradually raised to 230°C while stirring, and the esterification reaction was carried out for 10 hours to obtain trimethylolpropane tripalm kernel fatty acid ester (without purification treatment) A-1. The strong acid value was 0.7 mg KOH / g. 【0143】 <Production Example 2 (Production of A-2)> 1000 g of the above-mentioned trimethylolpropane tripalm kernel fatty acid ester A-1 (without purification treatment) and 15 g of catalyst adsorbent Kyoward 2000 (manufactured by Kyowa Chemical Industry Co., Ltd.) were charged into a reaction vessel, and catalyst adsorption treatment was carried out at 90°C for 1 hour while stirring under a nitrogen atmosphere. After that, filtration was performed using filter paper (filter paper No. 424, manufactured by Advantec) to obtain trimethylolpropane tripalm kernel fatty acid ester A-2. The strong acid value was 0 mg KOH / g. 【0144】<Production Example 3 (Production of A-10)> In a reaction vessel, 770 g (2.7 mol) of stearic acid, 355 g (2.7 mol) of 2-ethylhexyl alcohol, 2.5 g of p-toluenesulfonic acid as an esterification catalyst, and 0.7 g of a 50% aqueous solution of hypophosphorous acid as a color inhibitor were charged. Under a nitrogen atmosphere, the temperature was gradually raised to 180°C while stirring, and the esterification reaction was carried out for 10 hours. After that, it was cooled to 90°C. Then, 200 g of soft water was added, and the mixture was washed with water at 90°C for 30 minutes while stirring. After that, stirring was stopped and the mixture was allowed to stand for 2 hours to separate the oil layer and the water layer, and the water layer was discharged and removed. Then, the same washing treatment was repeated. After that, the oil layer was dehydrated at 130°C for 2 hours while stirring under a nitrogen atmosphere. After that, the mixture was filtered using filter paper (filter paper No. 424, manufactured by Advantec) to obtain 2-ethylhexyl alcohol stearate ester A-10. The strong acid value was 0 mg KOH / g. 【0145】 <Production Example 4 (Production of A-11)> Oleyl alcohol oleate ester A-11 was obtained using the same production method as in Production Example 3, except that 500 g (1.8 mol) of oleyl alcohol, 510 g (1.8 mol) of oleic acid, 2.5 g of p-toluenesulfonic acid, and 0.7 g of a 50% aqueous solution of hypophosphorous acid were used as raw materials. The strong acid value was 0 mg KOH / g. 【0146】 <Production Example 5 (Production of A-12)> Using 285 g (1.6 mol) of thiodipropionic acid, 865 g (3.2 mol) of oleyl alcohol, 2.5 g of p-toluenesulfonic acid, and 0.7 g of a 50% aqueous solution of hypophosphorous acid as raw materials, and the same production method as in Production Example 1 except that the esterification reaction temperature was set to 170°C, thiodipropionic acid dioleyl (without purification treatment) A-12 was obtained. The strong acid value was 0.7 mg KOH / g. 【0147】 <Production Example 6 (Production of A-13)> Thiodipropionic acid dioleil A-13 was obtained by the same production method as in Production Example 3, except that 285 g (1.6 mol) of thiodipropionic acid, 865 g (3.2 mol) of oleyl alcohol, 2.5 g of p-toluenesulfonic acid, and 0.7 g of a 50% aqueous solution of hypophosphorous acid were used as raw materials, and the esterification reaction temperature was set to 170°C. The strong acid value was 0 mgKOH / g. 【0148】 <Production Example 7 (Production of A-14)> Diisocetyl thiodipropionate A-14 was obtained using the same production method as in Production Example 3, except that 303 g (1.7 mol) of thiodipropionic acid, 815 g (3.3 mol) of isocetyl alcohol, 2.5 g of p-toluenesulfonic acid, and 0.7 g of a 50% aqueous solution of hypophosphorous acid were used as raw materials, and the esterification reaction temperature was set to 170°C. The strong acid value was 0 mgKOH / g. 【0149】 <Production Example 8 (Production of B2-2)> In a reaction vessel, 810 g (0.3 mol) of hydrogenated castor oil ethylene oxide 25 mol adduct, 250 g (0.9 mol) of stearic acid, 2.5 g of p-toluenesulfonic acid as an esterification catalyst, and 0.7 g of a 50% aqueous solution of hypophosphorous acid as a color inhibitor were charged. Under a nitrogen atmosphere, the temperature was gradually raised to 210°C while stirring, and the esterification reaction was carried out for 10 hours to obtain hydrogenated castor oil ethylene oxide 25 mol adduct tristearate (without purification treatment) B2-2. The strong acid value was 0.7 mg KOH / g. 【0150】 <Production Example 9 (Production of B2-3)> In a reaction vessel, 810 g (0.3 mol) of 25 mol hydrogenated castor oil ethylene oxide adduct, 250 g (0.9 mol) of stearic acid, 2.5 g of p-toluenesulfonic acid as an esterification catalyst, and 0.7 g of a 50% aqueous solution of hypophosphorous acid as a color inhibitor were charged. The mixture was heated gradually to 210°C under a nitrogen atmosphere with stirring, and the esterification reaction was carried out for 10 hours. Then, 15 g of the catalyst adsorbent Kyoward 2000 (manufactured by Kyowa Chemical Industry Co., Ltd.) was charged, and catalyst adsorption treatment was carried out at 90°C for 1 hour with stirring under a nitrogen atmosphere. After that, the mixture was filtered using filter paper (filter paper No. 424, manufactured by Advantec) to obtain 25 mol hydrogenated castor oil ethylene oxide adduct tristearate B2-3. The strong acid value was 0 mg KOH / g. 【0151】<Production Example 10 (Production of B2-4)> Hydrogenated castor oil ethylene oxide 20 molar adduct trioleate B2-4 was obtained using the same production method as in Production Example 9, except that the raw materials used were 810 g (0.4 mol) of hydrogenated castor oil ethylene oxide 20 molar adduct, 310 g (1.1 mol) of oleic acid, 2.5 g of p-toluenesulfonic acid, and 0.7 g of a 50% aqueous solution of hypophosphorous acid. The strong acid value was 0 mg KOH / g. 【0152】 <Production Example 11 (Production of B2-5)> Polyethylene glycol (molecular weight 600) dioleate B2-5 was obtained using the same production method as in Production Example 9, except that 600 g (1 mole) of polyethylene glycol (molecular weight 600), 550 g (1.9 moles) of oleic acid, 2.5 g of p-toluenesulfonic acid, and 0.7 g of a 50% aqueous solution of hypophosphorous acid were used as raw materials, and the esterification reaction temperature was set to 190°C. The strong acid value was 0 mg KOH / g. 【0153】 <Production Example 12 (Production of B2-6)> 280 g (1.4 mol) of polyethylene glycol (molecular weight 200) and 760 g (2.7 mol) of oleic acid were charged into a reaction vessel. The temperature was gradually raised to 210°C while stirring under a nitrogen atmosphere, and the esterification reaction was carried out for 10 hours to obtain polyethylene glycol (molecular weight 200) dioleate B2-6. The strong acid value was 0 mg KOH / g. 【0154】 <Production Example 13 (Production of B2-8)> Except for using 850 g (0.4 mol) of hydrogenated castor oil ethylene oxide adduct, 30 g (0.3 mol) of maleic acid, and 190 g (0.7 mol) of stearic acid as raw materials, an ester B2-8 of hydrogenated castor oil ether, maleic acid, and stearic acid was obtained using the same production method as in Production Example 12. The strong acid value was 0 mg KOH / g. 【0155】 【0156】 【0157】 【0158】 【0159】 【0160】 【0161】 As can be seen from Tables 1 to 6, the synthetic fiber treatment agent in the examples contained a smoothing component (A) and a surfactant (B), and the iodine value, strong acid value, and kinematic viscosity of the non-volatile components of the treatment agent were within the specified range, resulting in excellent low-temperature stability. On the other hand, the comparative example was not the synthetic fiber treatment agent of the present invention, and therefore exhibited poor low-temperature stability. 【0162】 The synthetic fiber treatment agent of the present invention is suitable for synthetic fiber filaments used in industrial materials such as tarpaulins, tire cords, seat belts, airbags, fishing nets, ropes, and slings, as well as for clothing such as woven and knitted fabrics.

Claims

1. A treatment agent for synthetic fibers containing a smoothing component (A) and a surfactant (B), wherein the iodine value of the nonvolatile component of the treatment agent is 5 to 100, the strong acid value of the nonvolatile component of the treatment agent is 0.0 to 0.3 mg KOH / g, and the kinematic viscosity of the nonvolatile component of the treatment agent is 60 mm at 25°C. ２ / s exceeding 1000mm ２ A treatment agent for synthetic fibers with a value of / s or less.

2. The synthetic fiber treatment agent according to claim 1, wherein the surfactant (B) contains an anionic surfactant (B1), the anionic surfactant (B1) contains an anionic surfactant (B1-1) having a sulfur element, and the anionic surfactant (B1-1) having a sulfur element contains at least one selected from an organic sulfonic acid compound represented by the following general formula (2) and an organic sulfonic acid compound represented by the following general formula (3). (In formula (2), a and b are integers greater than or equal to 0, such that a + b = 5 to 17. M is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group.) (In formula (3), c, d, and e are integers greater than or equal to 0, satisfying c + d + e = 4 to 16. M is a hydrogen atom, an alkali metal, an ammonium group, or an organic amine group.) 3. The synthetic fiber treatment agent according to claim 2, wherein the anionic surfactant (B1-1) having a sulfur element comprises an organic sulfonic acid compound represented by the general formula (2) and an organic sulfonic acid compound represented by the following general formula (3).

4. The synthetic fiber treatment agent according to any one of claims 1 to 3, wherein the smoothing component (A) includes an ester component having a structure in which an aliphatic polyhydric alcohol and a fatty acid are ester-bonded.

5. Sulfate ions (SO4) detected from the non-volatile components of the treatment agent by ion chromatography. ４ ２－ A synthetic fiber treatment agent according to any one of claims 1 to 4, wherein the content is 0.1 ppm or more and 600 ppm or less.

6. Chloride ions (Cl) detected from the non-volatile components of the treatment agent by ion chromatography. － A synthetic fiber treatment agent according to any one of claims 1 to 5, wherein the content is 0.1 ppm or more and 500 ppm or less.

7. Phosphate ions (PO) detected from the non-volatile components of the treatment agent by ion chromatography. ４ ３－ A synthetic fiber treatment agent according to any one of claims 1 to 6, wherein the content is 0.1 ppm or more and 200 ppm or less.

8. The synthetic fiber treatment agent according to any one of claims 1 to 7, wherein the surfactant (B) contains a nonionic surfactant.

9. A treatment agent for synthetic fibers according to any one of claims 1 to 8, further comprising an antioxidant.

10. A synthetic fiber obtained by applying a synthetic fiber treatment agent according to any one of claims 1 to 9 to a raw synthetic fiber.

11. A method for producing synthetic fibers, comprising the step of applying a synthetic fiber treatment agent according to any one of claims 1 to 9 to a raw synthetic fiber.

12. A fibrous structure comprising the synthetic fiber described in claim 10.

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